JP4428690B2 - Method and apparatus for producing polybutylene terephthalate film, and shape memory polybutylene terephthalate laminated film - Google Patents

Description

  The present invention relates to a method and apparatus for producing a polybutylene terephthalate film excellent in film thickness uniformity, heat shrinkage resistance and mechanical strength while being a thin film, and a shape memory useful as a packaging material having the polybutylene terephthalate film. The present invention relates to a polybutylene terephthalate laminated film.

  Since polybutylene terephthalate (PBT) resin has excellent mechanical strength, heat resistance, chemical resistance, impact resistance, electrical properties, etc., it has been attracting attention as an engineering plastic from the past. Have been used as injection products. Since PBT is also excellent in gas barrier properties and fragrance retention properties, if a thin PBT film excellent in film thickness uniformity and heat shrinkage resistance or a laminated film including the PBT film can be produced, it is useful as a packaging material. However, in PBT, (a) after crystallization, for example, when stretched in the longitudinal direction, it is not possible to stretch in the lateral direction thereafter, (b) because of low melt tension, rapid stretching is not possible, and (c) glass transition There is a problem that film wrinkles are likely to occur because the temperature is close to room temperature. Therefore, it is extremely difficult to form a polybutylene terephthalate resin into a clean packaging film having a uniform thickness of about 10 to 30 μm.

  As a method for producing a PBT film by biaxially stretching an unstretched film produced by the T-die method, JP-A-49-80178 proposes a method of simultaneously biaxially stretching an unstretched film at a predetermined temperature. JP-B-51-40904 and JP-A-51-146572 propose a method of successively biaxially stretching an unstretched film at a predetermined temperature and speed. However, in these methods, since the unstretched film produced by quenching the molten polybutylene terephthalate resin is biaxially stretched, the processing steps are complicated, and the heat shrinkage rate of the resulting film is large. In order to facilitate the biaxial stretching of polybutylene terephthalate film, a method of laminating with other resin films, a method of blending compatible resins such as polyethylene and polypropylene, etc. have been proposed, but any method It was difficult to reduce the film thickness to a film thickness of about 10 to 30 μm, which is optimal as a packaging film.

In general, the inflation molding method has higher productivity than the T-die method and is suitable for the production of thin films. However, the polybutylene terephthalate film produced by the inflation molding method has a problem that the film thickness unevenness is large and the heat shrinkage rate is large. For example, Japanese Patent Publication No. 7-33048 (Patent Document 1) discloses a PBT resin having an intrinsic viscosity of 1.0 or more and an extrusion resin temperature of the following formula:
Melting point (° C.) <Extruded resin temperature (° C.) <Melting point−26 + 53 × Intrinsic viscosity (° C.)
A method for forming a film by an inflation molding method so as to satisfy the above is proposed. However, in this method, the combination of the extrusion resin temperature and the extrusion resin pressure is not optimized, and the obtained PBT film has a relatively large heat shrinkage rate.

  PBT is a kind of polyester, but another typical polyester is polyethylene terephthalate (PET). PET film has excellent gas barrier properties, dimensional stability against heat, suitability for filling machines (no curling), etc., so laminated film containing PET film is used as a lid for instant food containers, for example. Yes. However, since PET film has high waist strength, it has poor properties (dead hold property) for keeping the lid open. Therefore, the lid body is easily closed after opening, and there is a problem that it is difficult to pour hot water.

  The laminated film constituting the lid material used for instant noodle containers is required not to be curled when sealed to the container, and to maintain the curled state when peeled from the container (has dead hold property). It is done. Usually, since the lid material is heat-sealed to the container, it is very useful if it has a shape memory property that does not curl before heat-sealing and curls by heat during heat-sealing.

  However, a packaging material made of a laminated film having shape memory properties has not been known so far. In general, a resin having shape memory property has a large elastic modulus change before and after the glass transition point. For example, (1) First, the shape memory mechanism is formed into an arbitrary shape M, and heated in the state of the shape M to cause crystallization (entanglement of crystal parts) or intermolecular crosslinking to generate a fixed point to store the shape. (2) Next, when an external force is applied at a temperature above the glass transition point and below the heating temperature, it is deformed to shape N, and is fixed to shape N by keeping the temperature below the glass transition point. (3) Glass transition point By heating as described above, the shape M is recovered without applying an external force. Although PET has shape memory, the glass transition temperature is about 70 to 80 ° C., so the temperature required for shape recovery is too high.

  In contrast, since PBT has a glass transition temperature of about 20 to 45 ° C., it can be a packaging material that can utilize shape memory at a practical temperature. For example, Japanese Patent Application Laid-Open No. 2-123129 (Patent Document 2) describes a shape memory resin made of a block copolymer of PBT and an aliphatic polylactone. Japanese Patent Application Laid-Open No. 2-269735 (Patent Document 3) describes a shape memory copolyester molded article made of polyethylene terephthalate copolymerized with a third component so that the crystal melting entropy is 3 cal / g or less. . Further, JP-A-2-240135 (Patent Document 4) describes a shape memory resin comprising a block copolymer of PBT and polyethylene glycol. However, none of these documents has a PBT shape memory resin formed into a film.

Japanese Patent Publication No. 7-33048 Japanese Patent Laid-Open No. 2-123129 JP-A-2-269735 JP-A-2-240135

  Accordingly, an object of the present invention is to provide a method and an apparatus for producing a polybutylene terephthalate film which is a thin film and has excellent film thickness uniformity, heat shrinkage resistance and mechanical strength.

  Another object of the present invention is to provide a polybutylene terephthalate laminated film having excellent shape memory properties and heat-resistant dimensional stability.

As a result of earnest research in view of the above object, the present inventors have found the following.
(A) In a method for producing a PBT film in which polybutylene terephthalate (PBT) resin is formed into a film by an air-cooled inflation molding method, the extrusion resin temperature is set to a melting point of PBT resin of −15 ° C. to the melting point of −5 ° C., and the extrusion resin pressure is set to By setting the pressure to 8.3 to 13.7 MPa, it is possible to produce a PBT film having excellent film thickness uniformity, heat shrinkage resistance and mechanical strength while being a thin film.
(B) (1) A laminated film formed by laminating the PBT film and another film or a film laminate is formed at a temperature T ₁ that is not higher than the glass transition temperature Tg of the PBT film while maintaining the first shape. (2) The resulting shaped laminate is deformed into a second shape at a temperature T ₂ that exceeds Tg, and (3) is cooled to a temperature T _{3 that is} equal to or lower than Tg. PBT laminated film having heat resistance and heat-resistant dimensional stability can be obtained.
(C) (1) (i) A laminated film of the PBT film and another film or film laminate is prepared in advance, and the film is applied at a temperature T _{4 above} Tg to below the melting point while maintaining this in the first shape. Or (ii) a laminated film having the first shape by laminating with another film or film laminate after shaping at the temperature T ₄ while holding the PBT film in the first shape to prepare, (2) the resulting shaping laminate is cooled to a temperature T ₅ below Tg is fixed to the first shape, (3) then the shaping laminate, the Tg super-said temperature after deforming the second shape at a temperature T ₆ below T _4, (4) by cooled Tg to a temperature below T ₇ for fixing the second shape, excellent shape memory properties and heat dimensional stability A PBT laminated film having properties can be obtained.
The present invention has been completed based on this invention.

That is, method for producing a polybutylene terephthalate film of the present invention, by air-cooling inflation method a molten polybutylene terephthalate resin extruded from the circular die tube is inflated by injection of air forms a bubble, the extrusion resin temperature ( The melting point of the polybutylene terephthalate resin is −15 ° C. ) to (the melting point −5 ° C. ) , the extrusion resin pressure is 8.3 to 13.7 MPa, and the neck of the bubble is the melting point −40 ° C. to the melting point -25 ° C), and the expanded portion of the bubble is gradually cooled to (the melting point -70 ° C) to (the melting point -40 ° C), and the frost line region of the bubble is (the melting point -130 ° C)- Slowly cool to (melting point −90 ° C.), and the bubble region above the frost line is higher than (glass transition temperature Tg of the polybutylene terephthalate resin) to (Tg + 65 ° C.) Characterized by holding each time.

  The intrinsic viscosity of the polybutylene terephthalate resin is preferably 0.8 to 1.5. The polybutylene terephthalate resin preferably contains 5 to 15% by mass of polyolefin and / or elastomer. The gap between the die lips is preferably 0.8 to 1.2 mm, and the die diameter is preferably 120 to 250 mm. The blow-up ratio is preferably 2.0 to 4.0. By setting the blow-up ratio to 2.0 to 4.0, it is possible to simultaneously stretch the bubbles in the longitudinal direction and the lateral direction with a good balance.

  In the method for producing a polybutylene terephthalate film of the present invention, (1) by blowing hot air from a first hot air blowing device provided in the vicinity of the annular die, the neck portion of the bubble has the melting point of −40 ° C. Slow cooling to the melting point −25 ° C., (2) by blowing hot air from a second hot air blowing device provided above the first hot air blowing device, the expansion portion of the bubble to the melting point The bubble frost line is formed by gradually cooling to −70 ° C. to the melting point −40 ° C., and (3) blowing hot air from a third hot air blowing device provided above the second hot air blowing device. The region is gradually cooled to the melting point of −130 ° C. to the melting point of −90 ° C., and (4) the bubble region is blocked from the external atmosphere by a partition provided with a gap around the bubble region above the frost line, The first to third hot air blowing devices Preferred ejection a warm air that blown up along the outer surface of the bubble area.

It is preferable that a plurality of hot air outlets are provided in the partition wall, and a rectifying plate is provided inside the partition wall in order to rectify the warm air blown from the first to third hot air blowing devices. Due to the hot air blown from the second hot air blowing device, the expanded portion of the bubble is gradually cooled while being kept in an amorphous state. To hold the bubble region to the glass transition temperature Tg temperature of the super to Tg + 65 ° C. of the polybutylene terephthalate resin, preferably provided with heating means to said partition wall.

In order to prevent the bubble from rolling, it is preferable to surround the bubble region with a cylindrical net. The temperature of the hot air ejected from the first and second hot air blowing devices is preferably 25 to 50 ° C. The temperature of the warm air to be ejected from the third temperature air blowing out device is preferably a glass transition temperature Tg super to a temperature of Tg + 65 ° C. of the polybutylene terephthalate resin.

The film obtained by the air-cooled inflation method of the present invention has a thickness variation of ± 1 to ± 3 μm at an average thickness of 8 to 30 μm, a crystallinity of 35 to 40%, and is exposed at 175 ° C. for 10 minutes. The thermal contraction rate in the longitudinal direction and the width direction is 0.4% or less.

The obtained air-cooled blown film may be further cold-drawn uniaxially or biaxially. This further improves the uniformity of film thickness and transparency. Cold stretching is preferably carried out in the polybutylene terephthalate resin having a glass transition temperature Tg super to Tg + 60 ° C. of the temperature of the. It is preferable that the formation of the tubular film by the air-cooled inflation method and the uniaxial or biaxial cold stretching are continuously performed. After the obtained tubular film is divided into two, it may be cold-drawn uniaxially or biaxially. It is preferable that the formation of the tubular film by the air-cooled inflation method, the splitting of the tubular film, and the uniaxial or biaxial cold stretching are continuously performed.

The apparatus for producing a polybutylene terephthalate film of the present invention comprises: (a) a molten polybutylene terephthalate resin having a temperature of (the melting point of the polybutylene terephthalate resin—15 ° C.) to (the melting point—5 ° C.) and 8.3 to 13.7 MPa. An annular die that extrudes into a tube with pressure ; (b) means for injecting air into the resulting polybutylene terephthalate tube to form bubbles; and (c) provided near the annular die for blowing hot air A first hot air blowing device that slowly cools the neck of the bubble to (the melting point −40 ° C.) to (the melting point −25 ° C.) ; and (d) provided above the first hot air blowing device A second hot air blowing device that gradually cools the expansion portion of the bubble to (the melting point −70 ° C.) to (the melting point −40 ° C.) by blowing out hot air ; and (e) the second hot air blowing It provided above the output device, jetting of hot air A third temperature air blowing out device for annealing a frost line region of the bubble (the melting point -130 ° C.) ~ (the melting point -90 ° C.) by Rukoto, above the (f) said third temperature air blowing out device And provided around the bubble area above the frost line, shuts off the bubble area from the external atmosphere, and moves the hot air blown from the first to third hot air blowing devices along the outer surface of the bubble area. ; and a partition wall for blowing up Te, the partition will have a heating means and a plurality of hot air outlet temperature of the bubble area (the glass transition temperature Tg of the polybutylene terephthalate resin) ultra to (Tg + 65 ° C.) It is characterized by holding .

  In the manufacturing apparatus of the present invention, it is preferable that a current plate is provided inside the partition wall. In order to prevent the bubbles from rolling, it is preferable to provide a cylindrical net surrounding the bubble region inside the partition wall. It is preferable that the expanded portion of the bubble is gradually cooled in an amorphous state by the hot air blown from the second hot air blowing device. It is preferable to further have means for cold drawing the obtained air-cooled blown film.

  The annular die, the air injection means, the first hot air blowing device, the second hot air blowing device, the third hot air blowing device, the air-cooled inflation means having the partition wall, and the cold drawing means are air-cooled. It is preferable to arrange continuously along the flow of the inflation film.

  The manufacturing apparatus of the present invention comprises a nip roll for taking up the tubular film formed by the air-cooled inflation means, and (a) a sheet taken up by the nip roll between the air-cooled inflation means and the cold-drawing means. A device for controlling the edge position of the tubular film in the form of an edge; and (b) a cutting means for dividing the tubular film whose edge position is controlled into two parts, and the air-cooled inflation It is preferable that the means, the edge position control device, the cutting means, and the cold drawing means are continuous in this order.

The first shape memory polybutylene terephthalate laminate film of the present invention is (1) obtained by the production method of the present invention , and has a film thickness variation of ± 1 to ± 3 μm at an average film thickness of 8 to 30 μm. A polybutylene terephthalate film having a thermal shrinkage of 0.4% or less when exposed to 175 ° C. for 10 minutes , and (2) a paper sheet, other resin film and metal. and at least one kind selected from the group consisting of foil, the polybutylene terephthalate temperature T ₁ of below the glass transition temperature of the film is shaped processed first shape, temperature T ₂ exceeding the glass transition temperature in the deforming the second shape, and then is fixed to the second shape by being cooled to a temperature T ₃ below the glass transition temperature, by exposure to the temperature above T _1, said Second shape Characterized in that return to the first shape from.

The temperature T ₁ is preferably 35 ° C. or less, more preferably 15 to 25 ° C., the temperature T ₂ is preferably more than 45 ° C. to 65 ° C. or less, and the temperature T ₃ is 15 to It is preferably 25 ° C.

The second shape memory polybutylene terephthalate laminated film of the present invention is obtained by (1) the production method of the present invention, and the variation in film thickness at an average film thickness of 8 to 30 μm is ± 1 to ± 3 μm. 35-40%, and a polybutylene terephthalate film having a thermal shrinkage of 0.4% or less in the longitudinal direction and the width direction when exposed at 175 ° C. for 10 minutes, and (b) a paper sheet, other resin film and metal Having at least one selected from the group consisting of foil, and a temperature T above the glass transition temperature of the polybutylene terephthalate film to less than the melting point T _Four At a temperature T equal to or lower than the glass transition temperature. _Five Fixed to the first shape by being cooled to the glass transition temperature above the temperature T _Four Less than temperature T ₆ At a temperature T equal to or lower than the glass transition temperature. ₇ Is fixed to the second shape by being cooled to the temperature T _Four When exposed to the above, the second shape returns to the first shape.

Temperature T _Four Is preferably 75-100 ° C, more preferably 90-100 ° C, the temperature T _Five Is preferably 40 ° C. or less, and the temperature T ₆ Is preferably 45 to 65 ° C., the temperature T ₇ Is preferably 40 ° C. or lower.

In a preferred embodiment of the present invention, the first shape Ri curled shape der, the second shape is Ru substantially flat shape or a reverse curl shape der. In another preferred example of the present invention, the first shape is a tray shape, and the second shape is a flat shape.

  It is preferable to form a large number of substantially parallel linear traces on at least one surface of the polybutylene terephthalate film so that the shape memory polybutylene terephthalate laminated film is substantially straight along the linear traces. Can be torn. The depth of the linear mark is preferably 1 to 40% of the thickness of the polybutylene terephthalate film. Specifically, the depth of the linear traces is preferably 0.1 to 10 μm, the width of the linear traces is 0.1 to 10 μm, and the interval between the linear traces is preferably 10 to 200 μm. Ceramic or metal may be deposited on at least one surface of the polybutylene terephthalate film.

  The example of the preferable layer structure of the shape memory polybutylene terephthalate laminated film of this invention has the said polybutylene terephthalate film, the said paper sheet, and a sealant film in order. Another example of a preferred layer configuration of the shape memory polybutylene terephthalate laminated film of the present invention is that having the polybutylene terephthalate film, the paper sheet, a rigid film, and a sealant film in this order. Still another example of a preferable layer configuration of the shape memory polybutylene terephthalate laminated film of the present invention includes the polybutylene terephthalate film, a rigid film, and a sealant film in this order. A light-shielding ink layer may be provided on the surface of the polybutylene terephthalate film on the paper sheet side or on the surface of the rigid film on the sealant film side.

  The shape memory polybutylene terephthalate laminated film of the present invention is useful as a packaging material, and particularly useful as a packaging material constituting a container lid.

  The method for producing a polybutylene terephthalate film by the air-cooled inflation molding method of the present invention is obtained because the extrusion resin temperature is set to the melting point of PBT resin −15 ° C. to the melting point −5 ° C. and the extrusion resin pressure is set to 8.3 to 13.7 MPa. The resulting film has a high crystallinity and is excellent in film thickness uniformity, heat shrinkage rate and mechanical strength while being a thin film. For this reason, the polybutylene terephthalate film of the present invention is suitable for applications such as various packaging materials, packaging bags, and lids for instant food containers.

  In particular, it has a polybutylene terephthalate film obtained by the air-cooled inflation molding method of the present invention, and another film or film laminate including at least one selected from the group consisting of paper sheets, other resin films, and metal foils. The shape memory polybutylene terephthalate laminated film in which the shape is memorized in a predetermined temperature range has excellent shape memory properties and heat-resistant dimensional stability, and is suitable for use as a lid material for instant food containers.

[1] Method for producing polybutylene terephthalate film
(I) Raw material polybutylene terephthalate resin The polybutylene terephthalate (PBT) resin used as a raw material is not particularly limited, but is preferably composed of a homopolymer containing 1,4-butanediol and terephthalic acid as constituent components. However, a diol component other than 1,4-butanediol or a cambonic acid component other than terephthalic acid may be included as a copolymer component as long as physical properties such as shape memory and heat shrinkability are not impaired. Examples of such a diol component include ethylene glycol, diethylene glycol, neopentyl glycol, 1,4-cyclohexane methanol, and the like. Examples of the dicarboxylic acid component include isophthalic acid, sebacic acid, adipic acid, azelaic acid, and succinic acid. Specific examples of preferred PBT resins include homo PBT resins commercially available from Toray Industries, Inc. under the trade name “Trecon”.

  The PBT resin is not limited to the case of being composed only of PBT, and may contain other thermoplastic resins depending on the purpose within a range not impairing the effects of the present invention. Other thermoplastic resins include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN); polyphenylene sulfide (PPS); polyamide (PA); polyimide (PI); polyamideimide (PAI); polyethersulfone ( Polyether ether ketone (PEEK); Polycarbonate; Polyurethane; Fluororesin; Polyolefin such as polyethylene and polypropylene; Polyvinyl chloride; Elastomer and the like. In particular, when the PBT resin contains a polyolefin such as polyethylene and polypropylene and / or an elastomer, the melt viscosity and the melt tension increase, so that the film formability during film production is improved and the mechanical strength of the resulting film is increased. And heat sealability is improved. Of these, the PBT resin preferably contains polyethylene. When other thermoplastic resins are contained, the proportion is preferably 5 to 15% by mass, more preferably 5 to 10% by mass, based on 100% by mass of the entire PBT resin. Accordingly, unless otherwise specified, the term “polybutylene terephthalate resin” as used herein should be understood to include both PBT alone and PBT + other thermoplastic resin compositions.

  The molecular weight of the PBT film is preferably relatively high. The higher the molecular weight, the easier it is to keep the expanded portion of the bubble in an amorphous state when the bubble of molten PBT resin extruded from the annular die is expanded by air injection. Specifically, the IV value (intrinsic viscosity) of the PBT film is preferably 0.8 to 1.5.

  PBT resins include known additives that are added to general thermoplastic resins and thermosetting resins, that is, stabilizers such as plasticizers, antioxidants and UV absorbers, antistatic agents, surfactants, dyes, Colorants such as pigments, lubricants for improving fluidity, crystallization accelerators (nucleating agents), inorganic fillers, and the like can be appropriately used depending on the required performance.

(II) Air-cooled inflation molding FIG. 1 shows the steps of a method for producing a PBT film by the air-cooled inflation molding method of the present invention. The tubular film extruded from the annular die 1 attached to the extruder 12 is rapidly expanded into a film having a predetermined width by feeding air into the inside from the air injection pipe 26 and sandwiched between the take-out nip rolls 13. Take-up and take-up by take-up reel 14. The annular die 1 has an annular die head 10 and a weld portion 11. There are no particular restrictions on the air injection means for supplying the air to be injected into the tubular film, and examples include means having a structure in which the air injection pipe 26 is connected to a blower, means having a structure in which the air injection pipe 26 is connected to a compressed air cylinder, and the like. Can do.

  In order to produce a PBT film, the PBT resin and desired additives are first kneaded. The kneading temperature and the kneading pressure are adjusted so that the extrusion resin temperature and the extrusion resin pressure described later fall within the scope of the present invention. When kneading is performed in an extruder such as a single screw extruder so that the kneading temperature does not become higher than necessary, the one having a screw structure that does not generate heat or one having an appropriate cooling device is used.

  The extrusion resin temperature of the PBT resin is −15 ° C. to the melting point −5 ° C., preferably the melting point −10 ° C. to the melting point −5 ° C., unless otherwise specified. The temperature of the extruded resin is measured by a temperature detector 112 (such as a thermocouple) provided in the resin flow path of the weld portion 11 that connects the outlet 110 of the extruder 12 and the inlet 111 of the die head 10. Since the extrusion speed of the resin is very high, it is estimated that the temperature at the outlet 110 of the extruder 12 and the outlet of the die head 10 is approximately within the temperature range of -15 ° C to -5 ° C. However, the structure of the weld portion 11 is not limited to the illustrated one. For example, when the PBT resin is a homopolymer, its melting point is 220 ° C., and therefore the extrusion resin temperature is 205 to 215 ° C., preferably 210 to 215 ° C. By setting the temperature of the extruded resin to a melting point of −15 ° C. to a melting point of −5 ° C., a PBT film having a high crystallinity and excellent film thickness uniformity and heat shrinkage resistance can be obtained.

Extrusion resin pressure is 8.3 to 13.7 MPa (85 to 140 kgf / cm ² ). Since the resin pressure in the die head 10 cannot be measured due to the configuration of the apparatus, the pressure measured by the pressure detector 121 provided at the extruder outlet 110 is set as the extrusion resin pressure. By setting the extrusion resin pressure to 8.3 to 13.7 MPa, it is possible to extrude a resin having a sufficient melt viscosity to form bubbles even if the extrusion resin temperature is from a melting point −15 ° C. to a melting point −5 ° C. The extrusion resin pressure is preferably 9.3 to 11.8 MPa (95 to 120 kgf / cm ² ). The extrusion resin pressure can be adjusted by changing the mesh of the screen pack 120 in the extruder or changing the gap between the annular orifices.

  The outer diameter of the die lip of the die head 10 is preferably 120 to 250 mm, and the die lip gap is preferably 0.8 to 1.2 mm.

  The bubble 3 pushed out from the annular die 1 is stretched not only in the MD (longitudinal direction) but also in the TD (lateral direction) while being gradually cooled by the cooling device. In FIG. 2, the bubble cooling device includes a first hot air blowing device 20 provided in the vicinity of the annular die 1, a second hot air blowing device 21 provided above the first hot air blowing device 20, A third warm air blowing device 22 provided above the second warm air blowing device 21, a partition wall 23 provided above the third warm air blowing device 22, and a heating means 24 provided inside the partition wall 23; And a cylindrical net 25 provided inside the partition wall 23 (on the bubble 3 side). In FIG. 2, 15 indicates a heat insulating material provided above the annular die 1, and 16 indicates a guide roll.

  In the apparatus having the above configuration, the arrangement of each of the hot air blowing devices 20 to 22 and the partition wall 23 is determined by the temperature control of the bubble 3 formed by the air-cooled inflation molding method. Therefore, the shape and temperature distribution of the bubble 3 will be described below. .

  The melted PBT resin or PBT resin composition is extruded from the annular orifice 100 of the die 1 to form a bubble 3. The bubble 3 immediately after the extrusion has a small diameter due to a low melt tension, so-called neck portion 31. Form. In the neck portion 31, the bubble 3 is mainly stretched to MD. Next, the bubble 3 is rapidly expanded to a predetermined bubble diameter. In the inflating portion 32, the bubble 3 is stretched simultaneously in the MD and TD. There is a frost line 34 in the vicinity of the upper part of the inflating part 32, where the PBT resin is cooled and solidified. The bubble 3 is further gradually cooled by the partition wall 23 and the heating means 24 provided in the bubble region 33 above the frost line 34.

In order to obtain a PBT film by the air-cooled inflation molding method as in the present invention, the temperature of each part of the bubble 3 is controlled as follows.
(a) Extrusion resin temperature is controlled to a melting point of -15 ° C to a melting point of -5 ° C.
(b) The neck portion 31 is gradually cooled to a melting point of −40 ° C. to a melting point of −25 ° C.
(c) In the expansion part 32, it is gradually cooled to a melting point of −70 ° C. to a melting point of −40 ° C.
(d) In the region of the frost line 34, it is gradually cooled to a melting point of −130 ° C. to a melting point of −90 ° C.
(e) In the bubble region 33, the PBT resin is kept above Tg to Tg + 65 ° C.

  The condition (a) is the same as described above, but the condition (b) is that the neck portion 31 is not gradually cooled to the melting point −40 ° C. to the melting point −25 ° C. Simultaneous biaxial stretching cannot be sufficiently achieved. That is, by gradually cooling the neck portion 31 to a melting point of −40 ° C. to a melting point of −25 ° C., the expanded portion 32 can be gradually cooled / held at a melting point of −70 ° C. to a melting point of −40 ° C. [Condition (c)]. When the PBT resin is a homopolymer, the neck portion 31 is preferably slowly cooled to 180 to 195 ° C. If the expansion part 32 is not maintained at a melting point of −70 ° C. to a melting point of −40 ° C., the expansion part 32 does not have an appropriate melt tension, and MD stretching becomes main, and a thin film cannot be formed. If the expansion part 32 is set to a melting point of less than −70 ° C., crystallization proceeds, so that the amorphous state cannot be maintained. When the PBT resin is a homopolymer, it is preferable that the expanded portion 32 is gradually cooled to 150 to 180 ° C.

  In order to satisfy such a temperature condition, the blow-up ratio (bubble diameter / die diameter) is preferably set to 2.0 to 4.0. In particular, the blow-up ratio is desirably 2.0 to 2.8.

  Regarding condition (d), by simultaneously cooling the bubble temperature in the region of the frost line 34 from the melting point −130 ° C. to the melting point −90 ° C., sufficient simultaneous biaxial stretching of the bubble 3 to the MD and TD is achieved. Can do. If the bubble temperature in the region of the frost line 34 is lower than the melting point −130 ° C., film wrinkles may occur. When the PBT resin is a homopolymer, the region of the frost line 34 is preferably slowly cooled to 90 to 130 ° C.

  Regarding condition (e), by keeping the bubble 3 above the TBT of the PBT resin to Tg + 65 ° C. or less above the frost line 34, it is possible to prevent the formation of film flaws and stabilize the formation of a uniform thin bubble 3. can do. Preferably, bubble region 33 is maintained at 90-110 ° C. If the temperature of the bubble region 33 is kept at Tg or less without providing the partition wall 23 and the heating means 24, non-uniform stretching may occur, and the bubble 3 as a whole becomes unstable. The Tg of PBT resin is generally 22-45 ° C. Tg was measured according to JIS K7121.

  In the present invention, it is preferable to further surround the outer periphery of the bubble region 33 with a cylindrical net 25 as shown in FIG. As a result, the temperature of the bubble region 33 can be further stabilized and the roll of the bubble 3 can be prevented.

In order to control the temperature of the bubble 3 as described above, the first hot air blowing device 20, the second hot air blowing device 21, the third hot air blowing device 22, the partition wall 23, the heating means 24, and the cylindrical net 25 are used. The arrangement of is as follows.
(i) First hot air blowing device 20
Hot air is jetted so that the temperature of the neck part 31 is gradually cooled to the melting point −40 ° C. to the melting point −25 ° C. The temperature of the warm air is preferably 25 to 50 ° C.
(ii) Second hot air blowing device 21
It is provided directly under the expansion part 32, and warm air is jetted out so that the temperature of the expansion part 32 is gradually cooled to the melting point −70 ° C. to the melting point −40 ° C. The temperature of the warm air is preferably 25 to 50 ° C.
(iii) Third hot air blowing device 22
It is provided immediately below the frost line 34, and hot air is blown out so that the temperature of the region of the frost line 34 is gradually cooled to the melting point -130 ° C to the melting point -90 ° C. The temperature of the hot air is preferably more than Tg of the PBT resin and not more than Tg + 65 ° C.
(iv) Partition wall 23 and heating means 24
The partition wall 23 is located above the third warm air blowing device 22 so as to surround the bubble region 33 and so that the warm air blown from the first to third warm air blowing devices blows up along the outer surface of the bubble region 33. Provide. The heating means 24 is provided inside the partition wall 23. By providing the partition wall 23 and the heating means 24, the bubble region 33 can be shielded from the influence of the external atmosphere (air temperature, temperature, etc.), and can always be kept above Tg to Tg + 65 ° C. of the PBT resin.
(v) Cylindrical net 25
It is provided so as to surround the bubble region 33 inside the partition wall 23.

  In the above method, there is no particular limitation on the means for supplying hot air to be blown out from each of the first to third hot air blowing devices, and examples include a blower capable of controlling temperature. The flow rate of the warm air blown from each of the first to third warm air blowing devices is appropriately adjusted so that the bubble temperatures in the regions of the neck portion 31, the expansion portion 32, and the frost line 34 are in the above temperature ranges, respectively. . If the stable slow cooling effect cannot be obtained, the bubble 3 becomes unstable. Therefore, the temperature of the hot air is controlled so as not to change as much as possible.

  The material of the partition wall 23 is not particularly limited, but is preferably an acrylic resin so that the bubble region 33 surrounded by the partition wall 23 can be observed. If the bubble region 33 can be surrounded from four sides, the shape of the partition wall 23 is not particularly limited, and examples thereof include a cylindrical structure and a rectangular parallelepiped structure, and a cylindrical structure is preferable. As the heating means 24 provided inside the partition wall 23, for example, a rod-shaped or ribbon-shaped electric heater can be used. It is preferable to provide a plurality of rod-shaped electric heaters. An aluminum foil may be attached to the inner surface of the partition wall 23 to block heat radiation. If necessary, a means for blowing cold air of about room temperature may be provided below the partition wall 23 (immediately above the third hot air blowing device 22). This facilitates not only the temperature adjustment inside the partition wall 23 but also the air flow adjustment inside the partition wall 23.

  As shown in FIG. 2, it is preferable to provide a hot air outlet 230 at the upper part of the partition wall 23. By providing the warm air outlet 230, the warm air ejected from the first to third warm air blowing devices can be rectified. For this reason, it is possible to prevent the bubbles 3 from rolling due to warm air. Two or more hot air outlets 230 are preferably provided, and more preferably 2 to 4 hot air outlets 230 are provided. In the example shown in FIG. 2, the hot air discharge port 230 is provided on the upper portion of the side surface 231 of the partition wall 23, but may be provided on the upper surface 232 of the partition wall 23. However, the number and the diameter of the hot air outlets 230 are set such that the heat retention by the partition wall 23 is not impaired.

  As shown in FIG. 2, a ring-shaped rectifying plate 28 is preferably provided on the inner upper portion of the partition wall 23. By providing the current plate 28, the ability to rectify the warm air blown from the first to third warm air blowing devices is improved, and the roll 3 is prevented from rolling. As shown in FIG. 2, the rectifying plate 28 preferably extends from the vicinity of the cylindrical net 25 to the vicinity of the inner surface of the partition wall 23. There are no restrictions on the structure of the current plate 28, and the structure is partitioned by plates arranged in one direction as shown in FIG. 2 and FIG. 3 (a), and is divided into a grid as shown in FIG. 3 (b). Examples of such a structure include a punching plate having a large number of round holes as shown in FIG. The aperture ratio of the current plate 28 is preferably 40 to 60%. There are no particular limitations on the material constituting the current plate 28, and examples thereof include aluminum and synthetic resin. There is no particular limitation on the number of the rectifying plates 28 to be installed, but usually one sheet may be provided.

  As the fibers constituting the cylindrical net 25, natural fibers such as silk and cotton, plastic fibers such as nylon, polypropylene and polyester, metal fibers such as stainless steel, copper, brass and nickel can be used. When a net-like net is used as the cylindrical net 25, the net is preferably 5 to 20 mesh, more preferably 8 to 10 mesh.

  Film formation by the air-cooled inflation molding method of PBT resin in the present invention is possible by maintaining the above requirements, and general conditions of the inflation method can be applied to other conditions. That is, using a crosshead die, the tube-shaped molten PBT resin is extruded upward or downward, the end is sandwiched between pinch rolls, air is fed into it, and the die is continuously wound while being inflated to a predetermined size. Alternatively, it can be reversed to prevent uneven thickness.

  According to the manufacturing method of the present invention, each part of the bubble (immediately after extrusion, the neck part, the expansion part, the frost line area, and the bubble area) is always maintained at a desired temperature, so that the quality is always uniform. Furthermore, high-speed film formation is possible.

(III) Stretching process The PBT film (inflation PBT film) obtained by the above-described air-cooled inflation molding is further uniaxially cold-stretched in the longitudinal direction or the transverse direction at a temperature exceeding Tg to Tg + 60 ° C. of the PBT resin, You may carry out biaxial cold drawing sequentially in a longitudinal direction and a transverse direction. As a result, the inflation PBT film can be further thinned, and the film thickness uniformity and transparency can be improved. A preferred cold stretching temperature is 55 to 65 ° C. The stretching ratio of the uniaxial cold stretching is preferably 2 times or more in the longitudinal direction or the transverse direction, and more preferably 2 to 6 times. When uniaxial cold drawing is performed, it is preferably performed in the longitudinal direction. The stretching ratio of such sequential biaxial cold stretching is preferably 4 times or more in terms of surface magnification, and more preferably 4 to 16 times.

  Generally, when a PBT film is stretched at a temperature exceeding Tg + 60 ° C., crystals are oriented in the stretching direction, so that the tensile strength, elastic modulus, rigidity, etc. in the orientation direction are greatly improved. However, since the strength in the non-oriented direction is lowered, there is a problem that the film is torn when sequentially biaxially stretched at a temperature exceeding Tg + 60 ° C. On the other hand, when the PBT film is cold-drawn at a temperature of more than Tg to less than Tg + 60 ° C. of the PBT resin, the orientation of molecular chains in the drawing direction is less than that when the film is drawn at a temperature of more than Tg + 60 ° C. For this reason, the film does not tear even if successive biaxial stretching is performed on the inflation PBT film at a temperature exceeding Tg to Tg + 60 ° C. Moreover, even if uniaxial stretching is performed by cold stretching at a temperature of more than Tg to Tg + 60 ° C. or less, easy tearing does not occur. Further, by cold drawing at a temperature of more than Tg to Tg + 60 ° C. or less, the crystals are broken and fine spherulites are generated, so that the transparency of the film is improved.

  Since the PBT film obtained by air-cooled inflation molding is tube-shaped, if uniaxial cold stretching is performed by the roll method, or if sequential biaxial cold stretching is performed by the roll method and the tenter method, two tube-shaped PBT films are used. And then cold-drawn. To cut the tube-like inflation PBT film into two, in the state of a folded sheet, tear the paper horizontally from the folded part at both ends with respect to the sheet surface, or cut off both lateral ears with a slitter. .

  The process consisting of (a) air-cooled inflation molding, (b) cutting of the tubular inflation PBT film and (c) cold drawing, each of the blown PBT films cut into two after the air-cooled inflation molding is once separately wound. Although it may be a sequential process of performing cold stretching while sequentially rewinding each wound film, it is preferably an inline process in which the above steps (a) to (c) are continuously performed on a series of lines.

  4 (a) and 4 (b) show an example of an apparatus that cuts a PBT film obtained by air-cooled inflation molding into two in advance, turns it into a wound film, and then biaxially cold-draws sequentially in the longitudinal and transverse directions. Indicates.

  The unwound inflation PBT film 2 is stretched in the longitudinal direction by the slow driving roll 41 and the heating roll 43 between the fast driving rolls 42 in the longitudinal stretching section 4. The PBT film 2 stretched in the longitudinal direction is put in a tenter 5 (lateral stretching section), heated while holding both ends of the film, stretched in the lateral direction, and heat-treated. The PBT film 2 stretched also in the transverse direction is rapidly cooled by blowing cooling air in the cooling tower 27.

  For longitudinal stretching, as shown in detail in FIG. 5 (a), a large number of rotatable heating rolls 43 are arranged between the frontmost slow drive roll 41 and the rearmost fast drive roll 42, This is achieved by passing the inflation PBT film 2 between them and appropriately setting the peripheral speed ratio between the slow drive roll 41 and the fast drive roll 42. The temperature of the heating roll 43 is set so that the temperature of the inflation PBT film becomes a temperature of more than Tg to Tg + 60 ° C. or less.

  FIGS. 5B and 5C show another example of the longitudinally extending portion 4. FIG. 5B shows an example of a nip roll type, and FIG. 5C shows an example of a clover roll type. In any method, the inflation PBT film 2 is preheated with a plurality of preheating rolls 43, and then heated and stretched between the heated slow driving roll 41 and the fast driving roll 42, and then with a plurality of cooling rolls 44. Cooling.

  In the tenter 5, a chain (not shown) provided with a film clip roller 51 circulates endlessly along a rail (not shown). The tenter 5 is composed of three parts: a preheating part, a stretching part, and a heat treatment part. The PBT film 2 stretched in the longitudinal direction is heated by blowing hot air introduced from the hot air introduction hole 53 in each of the preheating portion, the stretching portion, and the heat treatment portion. In FIG. 4, reference numeral 52 denotes a gear, and reference numeral 54 denotes a hood for uniformly blowing hot air onto the PBT film 2. The temperature of the warm air blown out in the preheating part, the stretching part and the heat treatment part is set so that the temperature of the PBT film 2 passing through each part is maintained at a temperature of more than Tg to Tg + 60 ° C. or less. The rapid cooling by the cooling tower 27 causes the stretched PBT film 2 to have a temperature not higher than the glass transition temperature.

  When the inflation PBT film 2 is only uniaxially cold-stretched in the longitudinal direction or the transverse direction, the inflation PBT film 2 may be stretched only by the longitudinal stretching portion 4 or the transverse stretching portion 5 described above and then rapidly cooled.

  The uniaxial cold stretching in the longitudinal direction or the transverse direction and the sequential biaxial cold stretching in the longitudinal direction and the transverse direction are not limited to the roll method and the tenter method as shown in FIG. Can also be adopted. When the tubular method is employed, the step comprising (a) air-cooled inflation molding and (b) cold drawing is preferably an in-line step performed continuously on a series of lines.

  FIG. 6 shows an example of an in-line apparatus for continuously performing air-cooled inflation molding, cutting a tubular inflation PBT film, and cold drawing on a series of lines. The tube-like film 2 sandwiched and picked up by the take-up machine nip roll 13 is folded into a folded sheet, and is split horizontally with respect to the sheet surface by the cutter 18 from both ends of the folded PBT film 2 '. , 2 'are cold-drawn at the longitudinally-extending portions 4, 4. As shown in FIG. 6, an edge position control unit (EPC) 6 is preferably provided in front of the cutter 18. As a result, when cutting with the cutter 18, the ear end position (edge position) of the inflation PBT film can always be controlled to a fixed position, so that the tubular inflation PBT film 2 can always be uniformly divided. it can. The edge / position control device 6 shown in FIG. 6 has two guide rolls 61, 61, a connecting shaft 62 that connects the guide rolls 61, 61, and a sensor 63. The inclination of 61, 61 changes, and the ear end position (edge position) of the inflation PBT film 2 can be always controlled to be constant. The edge position control device is not limited to the one shown in the figure, and other known control mechanisms can be used.

  In the longitudinal stretching sections 4, 4, the inflation PBT films 2 ′, 2 ′ are cold-stretched between the heated slow drive rolls 45, 45 and the cooled fast drive rolls 46, 46. The temperature of the slow drive rolls 45, 45 is set such that the temperature of the inflation PBT film is a temperature exceeding Tg to Tg + 60 ° C. or less. The temperature of the fast drive rolls 46, 46 is set to a temperature equal to or lower than the Tg of inflation PBT, preferably lower than Tg. The stretching ratio may be adjusted by appropriately setting the peripheral speed ratio between the slow drive rolls 45, 45 and the fast drive rolls 46, 46. It is good also as a structure which can provide the tenter 5 (lateral direction extending | stretching part) shown in FIG. 4 after the longitudinal direction extended parts 4 and 4, and can perform cold extending | stretching to a horizontal direction further.

  As shown in FIG. 6, a heater 19 is provided, and the film after cold drawing is preferably heat-treated while being held horizontally by nip rolls 17 and 17. Instead of the heater 19, heat treatment may be performed by roll heating. The heat treatment is preferably performed at a temperature exceeding Tg of PBT to a melting point of −50 ° C. or less. The heat treatment after cold drawing can further improve transparency, tensile strength, heat shrinkage, and film thickness uniformity, and can also suppress generation of wrinkles. By performing the heat treatment at Tg + 60 ° C. or higher and melting point−50 ° C. or lower, linear easy tearability can be imparted to the film. In the case where linear easy tearability is not imparted to the film, the heat treatment may be performed at a temperature exceeding Tg to less than Tg + 60 ° C. By changing the heat treatment temperature in this way, the linear tearability of the film and the accompanying tear strength can be changed.

  By using the in-line apparatus shown in FIG. 6, a series of steps consisting of (a) air-cooled inflation molding, (b) cutting of a tubular inflation PBT film, and (c) cold drawing can be made efficient.

[2] Polybutylene terephthalate film The PBT film produced by the air-cooled inflation molding method described in [1] above has higher crystallinity and excellent film thickness uniformity than the conventional inflation molded film. And heat shrinkage is low. Specifically, the film thickness variation of an average film thickness of 8 to 30 μm is ± 1 to 3 μm, and the thermal shrinkage is 0.4% or less in MD (longitudinal direction) and TD (width direction). In the present specification, the variation in film thickness means that the thickness of the central portion and both end portions in the width direction of the PBT film was measured at two points, respectively, for a total of six points, and the difference between the maximum value and the minimum value was calculated. Value. A smaller value means a better result. The heat shrinkage is a value obtained by measuring the shrinkage of MD and TD when the PBT film is exposed at 175 ° C. for 10 minutes. ]. For this reason, a printed layer and a metal vapor deposition layer with little unevenness can be formed. In addition, there is little change in film dimensions in secondary processing such as heat sealing and printing.

  The heat shrinkage rate of the PBT film produced by the air-cooled inflation molding method described in [1] above is low as described above. The area from the neck of the bubble to the frost line is gradually cooled, and the vertical (MD) horizontal This is probably because the bubble region is stretched almost uniformly in the (TD) direction and the bubble region is kept above Tg to Tg + 65 ° C., so that no distortion (stress) occurs in the generated bubble.

  In particular, after air-cooled inflation molding, the film thickness variation of the average film thickness of 3 to 30 μm subjected to the cold stretching described in [1] above is 1 to 2 μm, and the thermal shrinkage in the cold stretching direction is 1% or less. It is. Moreover, there is no tearability in any direction, and the mechanical strength is excellent.

  The PBT film produced by the air-cooled inflation molding method described in [1] above has a higher degree of crystallinity than a conventional inflation molded film. Specifically, the degree of crystallinity measured by the X-ray method of the inflation PBT film of the present invention is 35 to 40%. For this reason, the PBT film produced by the air-cooled inflation molding method described in [1] above is excellent in mechanical strength. In contrast, the degree of crystallinity of a PBT film blown at an extruded resin temperature equal to or higher than the melting point is usually 30% or less. The crystallinity of PBT formed by the casting method is usually about 8 to 10%.

  The cold-drawn PBT film has a number of fine linear wrinkles extending in the cold drawing direction. That is, when the surface irregularities of a cold-drawn PBT film are measured with an AFM (Atomic Force Microscope), the height difference of the irregularities is usually 50 to 500 nm, and the width of the irregularities (the distance between the vertices of the linear wrinkles) is Usually 500-20000 nm. However, when biaxial cold stretching is performed sequentially in the longitudinal direction and the transverse direction, the linear wrinkles due to the cold stretching performed earlier disappear, and only the linear wrinkles due to the subsequent cold stretching remain on the surface of the PBT film. . Therefore, even if it performs sequential biaxial cold drawing, the direction of the linear wrinkle which a PBT film has is only one direction.

  The cold-stretched PBT film has the function of diffracting / scattering light by having the linear wrinkles as described above. For example, when a light source such as a light bulb is viewed through a PBT film having linear wrinkles, a single light streak with the same width as the light source is observed in the direction perpendicular to the direction of the linear wrinkles. For this reason, a decorative illumination light or the like can be produced by combining a PBT film having linear wrinkles and a light source. A laminated film obtained by laminating a plurality of PBT films having linear wrinkles so that the directions of the linear wrinkles are different from each other has a large light diffraction / scattering effect. Such a laminated film may be useful as a transparent film of a transparent electromagnetic wave shielding film obtained by laminating an electromagnetic wave shielding layer on a transparent film. Furthermore, there is a possibility that a laminated film of PBT films having linear wrinkles can be used as an electromagnetic wave shielding film. In particular, a honeycomb structure obtained by laminating a plurality of PBT films with linear wrinkles processed into a corrugated plate is considered to have a greater light diffraction / scattering effect and a higher transparent electromagnetic shielding property. Such a honeycomb structure may be useful as a soundproofing material.

[3] Shape memory polybutylene terephthalate laminate film The shape memory PBT laminate film of the present invention comprises: (a) a layer comprising a PBT film obtained by the production method of the present invention; and (b) a paper sheet, another resin film and a metal. And at least one selected from the group consisting of foil (hereinafter simply referred to as “other film or film laminate”).

(I) Layer structure
(1) Polybutylene terephthalate film
A PBT film obtained by the production method described in [1] above is used. Although there is no restriction | limiting in particular in the thickness of a PBT film, it is preferable to set it as about 5-50 micrometers practically, and it is more preferable to set it as about 8-30 micrometers.

(2) Other films or film laminates
(a) Paper sheet When the shape memory PBT laminated film is applied to the lid of an instant food container, it is preferable to have a layer made of a paper sheet as a dead hold property imparting layer. The paper type of the paper sheet layer is not limited and includes synthetic paper. The thickness of the paper sheet layer is preferably about 60 to 110 g / m ² , more preferably about 75 to 90 g / m ² . When the thickness of the paper sheet is less than about 60 g / m ² , the paper sheet is too weak to provide sufficient dead hold property. On the other hand, even if the thickness of the paper sheet exceeds about 110 g / m ² , only the cost increases and no further improvement in dead hold property is observed.

(b) Sealant film When shape memory PBT laminated film is applied to the lid of an instant food container, a sealant film for heat sealing is provided on the upper end flange of the container body. The sealant film can be formed of a polyethylene film, an unstretched polypropylene film, an ionomer resin film, a polystyrene film, or the like. The sealant film preferably has an easy peel property so that the lid can be easily peeled off from the container body. Therefore, it is preferable that the sealant film has relatively weak thermal adhesiveness. Moreover, a well-known hot melt can also be used as a heat sealing material.

  As the sealant film, for example, a laminated film of a polyethylene base film on the paper sheet side and a low molecular weight polyethylene film on the upper end flange portion side of the container body can be used. The thickness of the polyethylene base film is preferably about 10 to 40 μm, more preferably about 20 to 30 μm. The thickness of the low molecular weight polyethylene film is preferably about 5 to 20 μm, more preferably about 7 to 15 μm. Such a laminated polyethylene film is commercially available, for example, as 760FD (manufactured by Toray Synthetic Film Co., Ltd.). As the sealant film, a film made of a mixture of ethylene-vinyl acetate copolymer (EVA) and polyethylene can also be used. In the film made of this mixture, linear low density polyethylene (LLDPE) is preferable as the polyethylene. The thickness of the film made of this mixture is also preferably about 10 to 40 μm, more preferably about 20 to 30 μm. The thickness of the hot melt layer is preferably 10 to 50 μm, more preferably 20 to 40 μm.

As the sealant film, a film disclosed in Japanese Patent Application No. 2002-183197 may be used. The sealant film disclosed in Japanese Patent Application No. 2002-183197 is obtained by copolymerizing ethylene and an α-olefin having 3 to 18 carbon atoms, and has a density (JIS K6922) of 0.870 to 0.910 g / cm ³ , MFR (JIS K6921, 190 ° C., 2.16 kg load) is a linear ethylene / α-olefin copolymer having a load of 1 to 100 g / 10 min and a resin composition containing polystyrene. Thereby, even if the sealing surface of a container main body is either polyethylene or a polystyrene, the multi-sealant layer which can make sealing performance and easy-opening property compatible can be formed by heat-sealing the cover body of this invention.

(c) Rigid film In order to increase the rigidity of the shape memory PBT laminated film, a rigid film can be provided. Examples of the rigid film include a PET film, a biaxially stretched polypropylene film (OPP film), and a nylon film. Use of a biaxially oriented PET film having a different uniaxial orientation or degree of orientation as the PET film is advantageous when the shape memory PBT laminated film requires easy tearability. As a biaxially oriented PET film having a different uniaxial orientation or orientation degree, for example, “Emblet PC” (Unitika Ltd.) can be mentioned.

(d) Light-shielding ink layer When the shape-memory PBT laminated film needs light-shielding properties, a light-shielding ink layer or a metal foil layer is provided. The light-shielding ink is not particularly limited as long as it is an ink containing a black or dark pigment or dye such as carbon black. When a light-shielding ink layer is used, adverse effects on the environment during incineration can be avoided, and when a shape memory PBT laminated film is applied to the lid of a container for instant food, a metallic foreign object by a metal detector after sealing Can be detected. Thereby, not only the safety of instant food can be further increased, but also the metal detector can be used, so that the inspection cost can be significantly reduced. When a shape memory PBT laminated film having a metal foil layer is used for a lid of an instant food container, an aluminum foil is preferable as the metal foil. By using an aluminum foil layer, in addition to excellent light shielding properties, gas barrier properties, aroma retention properties, and the like can be obtained.

  The thickness of the light-shielding ink layer depends on the concentration of the black pigment or dye in the ink, but generally only needs to be sufficient to block ultraviolet rays and visible light. The thickness of the aluminum foil is preferably 3 to 15 μm, and more preferably 7 to 12 μm.

(3) Layer Configuration Example FIGS. 7 to 10 exemplify a layer configuration when the shape memory PBT laminated film is used as a packaging material for a lid of an instant food container. A laminated film 7 shown in FIG. 7 shows a layer structure having a PBT film 2, a paper sheet 71, and a sealant film 72 as a basic structure. Between the PBT film 2 and the paper sheet 71, there is an adhesive layer (I) composed of an adhesive layer 74 and an extrusion-laminated polyethylene layer (I) 73, and between the paper sheet 71 and the sealant film 72, There is an adhesive layer (II) composed of an adhesive layer 74 'and an extrusion-laminated polyethylene layer (II) 73'. In the case of the layer configuration example shown in FIG. 7, the outer layer composed of the PBT film 2 and the adhesive layer (I) (73 and 74), and the inner layer composed of the adhesive layer (II) (73 ′ and 74 ′) and the sealant film 72 Is preferably outer layer / inner layer = 100/35 to 100/100. Thereby, the curl property and dead hold property of the PBT film 2 can be functioned effectively. Here, “outside” and “inside” mean outside and inside of the container when the shape memory PBT laminated film is used as a lid of an instant food container or the like.

  FIG. 8 shows an example in which a rigid film 75 is provided between the paper sheet layer 71 and the sealant film 72 in order to increase the rigidity of the shape memory PBT laminated film. In FIG. 8, 73 ″ represents an extrusion-laminated polyethylene layer (III), and 74 ″ represents an adhesive layer (III).

  FIG. 9 shows an example in which a light-shielding ink layer 76 is provided on the inner surface of the polyethylene terephthalate layer 7 in order to impart good light-shielding properties. The light-shielding ink layer 76 is preferably printed in advance on a polyethylene terephthalate (PET) film. Further, the light-shielding ink layer 76 can be provided inside the PBT film 2 or can be provided on one side of the paper sheet layer 71 (for example, inside the paper sheet layer 71). The laminated film shown in FIG. 10 has a metal foil layer 77 as a layer imparting light shielding properties.

  11 and 12 exemplify a layer structure when the shape memory PBT laminated film is used as a packaging material for a lid of a container that contains semi-solid food such as jelly and pudding. The laminated film shown in FIG. 11 has a PBT film 2, a rigid film 75, and a sealant film 72 as a basic configuration. There is an adhesive layer (for example, a hot melt layer) 74 between the PBT film 2 and the rigid film 75, and there is an adhesive layer (for example, a hot melt layer) 74 ′ between the paper sheet 71 and the sealant film 72. . FIG. 12 shows an example in which a light-shielding ink layer 76 is provided on the inner surface of the rigid film 75 in order to impart good light-shielding properties.

  The lid used for containers containing semi-solid food does not require resealability after pouring, unlike the lid used for instant food containers. Often not. However, if only two layers of PBT film and polyethylene film are bonded to form a laminated film, even if the PBT film tries to recover the first shape, deformation will be easily absorbed by the polyethylene film, so the shape recovery ability is insufficient. There is a risk of becoming. Therefore, when manufacturing a shape memory PBT laminated film having a PBT film and a polyethylene film, it is preferable to provide the rigid film between the PBT film and the polyethylene film.

(II) Manufacturing method of shape memory polybutylene terephthalate laminated film Hereinafter, a manufacturing method of a shape memory PBT laminated film will be described in detail with reference to the drawings.
(1) First manufacturing method The first manufacturing method of the shape memory PBT laminated film is: (a) bonding the PBT film and the other film or film laminate, and While maintaining the shape, it is shaped (cold working) at a temperature T ₁ that is equal to or lower than the Tg of the PBT, and (c) the resulting shaped laminated film is formed into a second shape at a temperature T ₂ that exceeds the Tg. deformation processing, comprising the step of fixing the second shape by cooling to a temperature T ₃ below (c) Tg.

Hereinafter, a case where the first shape is a curl shape and the second shape is a flat shape will be described as an example. FIG. 13 shows an example of an apparatus for producing a shape memory PBT laminated film. The PBT film 2 unwound from the reel 80 on which the PBT film is wound is applied with an adhesive (for example, hot melt) 74 on one surface by the gravure rolls 131 and 131 through the guide roll 130, and in the drying furnace 132. Dry the adhesive layer. Thereafter, through the pressure adjusting roll 133, through the molten polyethylene 73 extruded from the die 134, another film or film laminate 82 unwound from the reel 81 is stacked on the adhesive layer while cooling roll 135 and rubber roll 135 ′ (Extrusion lamination) The obtained laminated film is shaped at a temperature T ₁ which is equal to or lower than the Tg of PBT while being conveyed by the cold working roll 136. Thereby, the curling property can be imparted to the PBT film of the laminated film. A curled laminating film (curled laminating film) 78 is flatly deformed between two nip rolls 137, 137 ′ while being rapidly annealed by a heater 138 at a temperature T ₂ exceeding Tg, and then a cooling roll by contacting with 139 cooled to a temperature T ₃ below the Tg. Thereby, a flat shape can be fixed. Thereafter, the curled laminated film is wound up with a reel in the reverse curl direction to form a wound film 83 (shape memory PBT laminated film 7). In this specification, the curling property is different from the dead hold property that can maintain the state when the shape memory PBT laminated film 7 is warped, and by exposing the shape memory PBT laminated film 7 to a temperature higher than the temperature imparted with the curling property. It means the property of returning from the second shape (flat shape, reverse curled shape, etc.) given after the curling property is imparted (the shape memory PBT laminated film 7 can be warped).

Although it is essential that the cold working temperature T ₁ is equal to or lower than the Tg of PBT, it is preferably 35 ° C. or lower, and more preferably 15 to 25 ° C. The temperature T ₃ for cooling the curled laminated film 78 after annealing is essential to be not more than the above Tg, but is preferably 15 to 25 ° C. PBT films generally have a Tg of about 20-45 ° C.

The annealing process for flatly deforming the curled laminated film at a temperature T ₂ exceeding Tg must be performed to such an extent that the curling property imparted by the cold working is not lost. Therefore temperature T ₂ is preferably at most 45 ° C. Ultra to 65 ° C., and deforming in terms of rapidly heated to this temperature range and a grilled 30-60 seconds. The tension applied to hold flat between the two nip rolls 137, 137 'is 5-10 kgf / m width. In addition, after the annealing process at the temperature T _2, it is preferable to rapidly cool to the temperature T ₃ . In FIG. 13, the heaters 138 and 138 are heated from both sides of the curled laminated film 78, but the heater 138 may be installed only on the PBT film side of the curled laminated film 78. The heated air exiting from the heater 138 may be blown onto the PBT film of the curlable laminated film 78 using a nozzle.

In the example shown in FIG. 13, the curled laminated film 78 is cooled to a temperature T _{3 and} then wound in the opposite curl direction (with another film or film laminate layer inside), but is applied by cold working. In order to prevent the curled property from being lost and suppress curling shape recovery as much as possible, it is preferable that the winding temperature and the temperature stored in the wound state are around T ₁ . As a result, the shape memory PBT laminate film 7 can be held in a flat state, so that the curl laminate film 78 when the wound film 83 (shape memory PBT laminate film 7) is rewound is substantially flat.

  When the shape memory PBT laminated film is used as a lid for instant food containers or semisolid food containers, the shape memory PBT laminated film is the above-mentioned [3] (I ) Prepare in advance so as to have the layer structure as described in (3). The other film or film laminate 82 may be formed by either an extrusion lamination method or a dry lamination method, but is preferably formed by an extrusion lamination method.

Regarding how to wrap the laminated film around the cold work roll 136, as shown in FIG. 13, the angle θ ₁ formed by the winding direction and the unwinding direction of the laminated film is in the range of 45-60 °. Is preferred. Thereby, sufficient curling property can be imparted to the PBT film 2. In order to set the angle θ ₁ to a desired value, the positional relationship between the cold working roll 136 and the pressure adjusting roll 133 ′ may be adjusted as appropriate. The diameter of the cold work roll 136 is preferably 20-80 cm. Thereby, sufficient curling property can be imparted to the PBT film 2. Usually, the peripheral speed of the cold working roll 136 is 30 to 100 m / min.

  When the PBT film 2 and another film or film laminate 82 are bonded between the cooling roll 135 and the rubber roll 135 ', the pressure adjusting roll 133 is used while applying a tension of usually 4 kgf / m width or more to the PBT film 2. . In particular, by applying a tension of 10 to 20 kgf / m width to the PBT film 2, the PBT film 2 can be adhered to another film or film laminate 82 while being stretched in the longitudinal direction so as to be elastically stretchable. Thus, the PBT film 2 can be bonded to another film or film laminate 82 in the stretched state in which the elastic restoring force is held. The stretched state in which the elastic restoring force is maintained is a state in which the PBT film 2 retains a force for contracting to the original shape when the force for fixing the stretching of the PBT film 2 is released. For this reason, the curl property of the shape memory PBT laminated film 7 can be further improved. The elastic stretchable elongation is generally an elongation that is extended by about 1 to 3% to the extent that the PBT film does not appear wrinkled by stretching.

  In the example shown in FIG. 13, the other film or film laminate 82 is bonded to only one side of the PBT film 2, but the other film or film laminate 82 is bonded to both sides of the PBT film 2 and then curled. It is also possible to impart sex.

  FIG. 14 shows another example of an apparatus for producing a shape memory PBT laminated film. The same members or portions as those in the example shown in FIG. This example is the same as the example shown in FIG. 13 except that the PBT film 2 and another film or film laminate 82 are bonded by the dry lamination method. The PBT film 2 provided with the adhesive layer is passed between the pair of heating rolls 140 and 140 while passing another pressure adjustment roll 133 and another film or film laminate 82 on the adhesive layer. However, when a strong adhesive strength is required, it is preferable to bond the PBT film 2 and another film or film laminate 82 by the extrusion lamination method shown in FIG.

Next, an example in which the shape of the shape memory PBT laminated film is a tray shape as the first shape and a flat shape as the second shape will be described. FIG. 15 shows an example of an apparatus for producing such a shape memory PBT laminated film. The same members or portions as those in the example shown in FIG. First, a PBT film and another film or film laminate are bonded by an extrusion lamination method or a dry lamination method to form a laminated film having another film or film laminate on one side or both sides of the PBT film. The obtained laminated film 84 is fed out by pressure adjusting rolls 133 and 133 and cold-worked at the above temperature T ₁ while pressing the pressing die 141 that imparts the tray shape, and the shape along the outer shape of the pressing die 141 is interrupted. Is granted. The shaping laminate 85 obtained, through between a pair of annealing rolls 142 and 142, substantially flattened by annealed at the above temperature T _2, then cooled by a cooling device 143, 143 to the temperature T ₃ . The substantially flattened deformed laminated film 85 is wound up with a winding roll 144 of the same type as the pressing die 141 while being laminated with the coating film 87 rewound from the reel 86 to obtain a wound film. As a result, deformation along the outer shape of the pressing die 141 is made latent, and a laminated film having no apparent deformation is obtained. The cold working at the temperature T ₁ performed while pressing the pressing die 141 against the PBT film 2 may be performed for 10 to 60 seconds. In the example shown in FIG. 15, the tray-shaped pressing die 141 is used, but a pressing die having a desired shape for which shape storage is desired can be used.

(2) Second manufacturing method The second manufacturing method of the shape memory PBT laminated film is the following: (a) (i) While maintaining the laminated film containing the PBT film in the first shape, the temperature T is above Tg to below the melting point T. ₄ in either processed excipient, laminated with a first shape by bonding with another film or film laminate after shaping at a temperature T ₄ while retaining the (ii) PBT film first shape (B) The obtained shaped laminated film is cooled to a temperature T _{5 of} Tg or less and fixed to the first shape, and (c) the shaped laminated film is then heated from Tg to T _It includes a step of deforming the second shape at a temperature T ₆ of less than _{4 and} then cooling to a temperature T ₇ equal to or lower than Tg and fixing to the second shape.

The PBT resin has a Tg of 22-45 ° C., which is close to room temperature, and can be easily heated to a temperature above Tg and cooled to below Tg. Moreover, since the melting point is as high as about 230 ° C., the temperature range from Tg to the melting point is wide, and the difference between the temperature T ₄ and the temperature T ₅ can be increased. Therefore, the operations (A) to (D) can be easily performed. Hereinafter, a case where the first shape is a curl shape and the second shape is a flat shape will be described as an example.

FIG. 16 shows an example of an apparatus for manufacturing a shape memory PBT laminated film by the second manufacturing method. In this example, another film or film laminate is bonded to a shaped PBT film that has been previously imparted with curl properties. The process from applying the adhesive 74 to one surface of the PBT film 2 and drying the adhesive layer in the drying furnace 132 is the same as the example shown in FIG. As shown in FIG. 16, the PBT film 2 after the adhesive layer has been dried is sent out by the pressure adjusting roll 133, and the above temperature is conveyed while being transported by the heating roll 145 for shaping with the surface having no adhesive layer as the contact surface. imparting curl by treatment with T _4. Thereafter, while another film or film laminate 82 is stacked on the adhesive layer of the PBT film 2, the heating roll 145 and the roll 145 ′ that contacts the heating roll 145 are passed to bond them together. The obtained curled laminated film 78 is cooled to a temperature T ₅ which is equal to or lower than the above Tg by bringing it into contact with a cooling roll 139, and then wound up with a reel in a reverse curl direction to form a wound film 83. The wound film 83 thus obtained, heat treatment at a temperature T ₆ under the Tg ultra-temperature T _4, then obtain a shape-memory PBT laminate film 7 by cooling to a temperature T ₇ below the Tg. On which the wound film 83, heat treatment at a temperature T _6, then potentially the curl shape of the laminated film by cooling to a temperature T _7, and apparently substantially flat laminated film. There is no limitation on the means for heating or cooling the wound film 83, and examples thereof include a method of putting the wound film 83 in a tank and heating the periphery of the tank with a heater or cooling with a cooling device.

Heating temperature T ₄ in the heating roll 145 is to require that a temperature below Tg ultra-melting point of PBT, is preferably from 75 to 100 ° C., and more preferably 90 to 100 ° C.. Although it is essential that the cooling temperature T ₅ in the cooling roll 139 is equal to or lower than the above Tg, it is preferably 40 ° C. or lower. The curled laminated film 78 may be cooled by using cooling air instead of the cooling roll 139. Heating temperature T ₆ of winding the film 83, as essential is less than the Tg ultra-temperature T _4, but is preferably from 45 to 65 ° C., and more preferably 45 to 50 ° C.. The heat treatment at temperature T ₆ is preferably performed for about 24 hours. Winding the film 83 cooling temperature T ₇ after heat treatment the is mandatory to or less than the Tg, but preferably at 40 ° C. or less. In the example shown in FIG. 16, in order to obtain a substantially flat shape as the second shape, the curled laminated film is wound in the reverse curl direction (with another film or film laminate layer inside). The film can be flattened efficiently.

About how to wind the PBT film 2 around the heating roll 145, it is preferable that the angle θ ₂ formed by the winding direction and the unwinding direction of the PBT film 2 shown in FIG. 16 is in the range of 45 to 60 °. . Thereby, sufficient curling property can be imparted to the PBT film 2. In order to set the angle θ ₂ to a desired value, the positional relationship between the heating roll 145 and the pressure adjusting rolls 133 and 133 may be adjusted as appropriate. The diameter of the heating roll 145 is preferably 60 to 80 cm. Thereby, sufficient curling property can be imparted to the PBT film 2. Usually, the peripheral speed of the heating roll 145 is 30 to 100 m / min.

  When the PBT film 2 and another film or film laminate 82 are bonded together by passing between the heating roll 145 and the contact roll 145 ′, as described in the first manufacturing method in (1) above. The PBT film 2 is usually subjected to a tension of 4 kgf / m width or more by a pair of pressure adjusting rolls 133, 133. Similar to the first manufacturing method, it is preferable to apply a tension of 10 to 20 kgf / m width to the PBT film 2.

FIG. 17 shows another example of an apparatus for manufacturing a shape memory PBT laminated film by the second manufacturing method. The same members or portions as those in the example shown in FIG. In this example, after a laminated film is produced in advance by bonding a PBT film and another film or a film laminate, curling properties are imparted to the PBT film. The process until the PBT film 2 and another film or film laminate 82 are bonded by the pair of heating rolls 140 and 140 is the same as the example shown in FIG. The obtained laminated film is shaped at a temperature T ₄ exceeding Tg of the PBT to less than the melting point while being conveyed by the heating roll 145. Thereby, the curling property can be imparted to the PBT film of the laminated film. The obtained curled laminated film 78 is cooled to a temperature T ₅ which is equal to or lower than the above Tg by bringing it into contact with a cooling roll 139, and then wound up with a reel in a reverse curl direction to form a wound film 83. The obtained wound film 83 is heat-treated at a temperature T ₆ above Tg to below T _{4 as} described above, and then cooled to a temperature T ₇ below Tg to obtain a shape memory PBT laminated film 7 .

In the example shown in FIG. 17, the requirements regarding the temperatures T _{4 to} T ₇ are the same as those in the example shown in FIG. The angle θ ₃ formed by the winding direction and unwinding direction of the laminated film 78 is preferably in the range of 45 to 60 °. In the example shown in FIG. 17, the other film or film laminate 82 is bonded to only one side of the PBT film 2, but the other film or film laminate 82 is bonded to both sides of the PBT film 2 and then curled. It is also possible to impart sex.

Also by the second manufacturing method, a shape memory PBT laminated film having a tray shape as the first shape and a flat shape as the second shape can be manufactured. The manufacturing apparatus in that case may be the same as that shown in FIG. 15, and will be described with reference to FIG. First, a PBT film and another film or film laminate are bonded together to produce a PBT laminated film having the other film or film laminate on one or both sides of the PBT film. The obtained film laminate 84 is subjected to a heat treatment at a temperature T ₄ exceeding Tg of the PBT to less than the melting point while pressing the pressing die 141 that imparts the tray shape through the pair of pressure adjusting rolls 133, 133, and the pressing die. The shape along the outer shape of 141 is given intermittently. The obtained shaped laminated body 85 is cooled to a temperature T ₅ which is equal to or lower than the above Tg by contacting with a cooling tray-shaped pressing die or cooling air provided at the subsequent stage of the pressing die 141, and then a pair of heating rolls 142, by passing between 142 and heated at a temperature T ₆ under the Tg ultra-temperature T _4, then flattened by cooling to a temperature T ₇ below the Tg by the cooling device 143, 143. The heat treatment at the temperature T ₄ performed while pressing the pressing die 141 against the film laminate 84 may be performed for 10 to 60 seconds.

(III) Shape Memory Polybutylene Terephthalate Laminate Film The shape memory PBT laminate film obtained by the first method substantially recovers the first shape by the shape recovery ability at a temperature of T ₁ or higher. PBT films, but the reason is not clear to recover the first shape by T ₁ or more temperature be fixed to the second shape by the annealing and cooling steps, for example, high cold working at temperatures T ₁ Strain is retained in the entanglement of the molecular chain, and most of this strain is not relaxed by short-time annealing at temperature T ₂ , so it is considered that the first shape is recovered at a temperature of T ₁ or higher.

The shape memory PBT laminated film obtained by the second method substantially recovers the first shape by the shape recovery ability at a temperature of T ₄ or higher. PBT films, be fixed to the second shape by the heat deformation and cooling steps, but the reason is not clear to recover the first shape at T ₄ or higher, rubbery, for example a temperature T ₄ or more it is easily heated shaping process for a region, deformed since it is glassy region the temperature T ₅ are fixed, the are alleviated some variations in the temperature T ₄ at the heating deformation at the temperature T ₆ However, the orientation of most of the molecular chains does not change, so it is considered that the first shape is recovered at a temperature of T ₄ or higher.

The shape memory PBT laminated film that can recover the first shape is useful as various packaging materials. In particular, the shape memory PBT laminated film that stores the curl shape manufactured by the method described in (2) above can sufficiently curl the lid without using a metal such as aluminum foil. It is suitable as a packaging material used for a container lid. When manufacturing an instant food container, the shape memory PBT laminated film is punched out by a lid sealing device, and the obtained lid is immediately heat sealed to the container. At the time of heat sealing, the sealing part of the lid body is usually heated to 120 to 160 ° C. by the sealing head of the lid material sealing device, but at that time, heat is also applied to parts other than the sealing part of the lid body. Processed under temperature conditions of ₁ or T ₄ or higher. Therefore, the lid body recovers its curl shape and is flat while being sealed by the container, but exhibits a curl shape by peeling from the container. In particular, when the PBT film is bonded to a paper sheet in the stretched state while retaining the elastic restoring force as described above, the curling property is further improved.

[4] Method for Producing Container with Shape Memory Polybutylene Terephthalate Laminated Film Lid Hereinafter, a method for producing a container with shape memory PBT laminated film lid will be described. The shape memory PBT laminated film 7 obtained by the method described in (2) above is apparently substantially flat in the manufacturing process, and further stored as a wound film 83, so that it is apparently substantially flat when unrolled. It is. However, when the shape recovery temperature is relatively low, when storage is prolonged, when exposed to room temperature in the summer high temperature period, etc., the curl shape gradually recovers during storage, or shape memory is stored by winding during storage There may be a warp on the opposite side of the curl shape.

  A container with a lid made of shape memory PBT laminated film is manufactured by punching a shape memory PBT laminated film storing a curl shape and heat-sealing the container, but unwinding the shape memory PBT laminated film At times, if the surface is not substantially flat, heat sealing to the container cannot be performed, or even if possible, the lid body will be bent and defective. Therefore, when manufacturing a container with a lid, the shape memory PBT laminated film which is not flat when unrolled is made almost flat just before heat sealing.

FIG. 18 shows an example of an apparatus for manufacturing a container having a shape memory PBT laminated film lid. The shape memory PBT laminated film 7 unwound from the wound film 83 is annealed using the heaters 147 and 147 while being held flat between the two nip rolls 146 and 146 ′ at a temperature T ₈ exceeding the Tg of PBT, Apparently almost flat. The substantially flat shape memory PBT laminated film 7 is punched by a lid material sealing device 150 in which the seal head 151 moves up and down, and immediately heat sealed to the container 170. An inert gas can be blown into the container as necessary.

However, the annealing at the temperature T ₈ is performed to such an extent that the curl property stored in the shape memory PBT laminated film is not lost. Thus preferably the temperature T ₈ is 80 to 120 ° C., and more preferably 90 to 100 ° C.. The shape-memory PBT laminate film is rapidly heated to a temperature T _8, and a 30 to 60 seconds baked on that held flat. The tension applied to keep flat between the two nip rolls 146, 146 'is 5-10 kgf / m width. The running speed of the normal shape memory PBT laminated film 7 is 30 to 100 m / min. In FIG. 18, the heaters 147 and 147 are heated from both sides of the shape memory PBT laminated film 7, but when the shape memory PBT laminated film 7 has a PBT film only on one side, the heater 147 is installed only on the PBT film side. May be. The heated air exiting from the heater 147 may be blown onto the PBT film of the shape memory PBT laminated film 7 using a nozzle.

  Since the punching process of the lid and the heat sealing to the container 170 are performed intermittently, the shape memory PBT laminated film 7 does not bend between the guide roll 149 and the contact roll 152, and is kept at a constant tension. In addition, it is preferable to provide a deflection preventing roll 148 that is movable up and down as shown in FIG. In FIG. 18, reference numeral 88 denotes a wound film made of the shape memory PBT laminated film 7 after the lid is punched out.

At the time of heat sealing, the sealing part of the lid body is usually heated to 120 to 160 ° C. by the sealing head 151 of the lid material sealing device, but at that time, heat is also applied to parts other than the sealing part of the lid body, It is processed under temperature conditions of T ₁ or T ₄ or higher. Therefore, the lid body recovers its curl shape and is flat while being sealed by the container, but exhibits a curl shape by peeling from the container.

[5] Container for food The container lid obtained by the production method described in [4] above exhibits a curl shape by shape memory when peeled from the container. For example, when the shape memory PBT laminated film is applied to the lid of an instant food container, as shown in FIG. 20, when the lid 7 is peeled from the container body 170 to the mark 161 with the tab portion 160 of the lid 7 The flap part formed by opening is kept sufficiently curled without having an aluminum layer. In particular, the curling property is further improved when the PBT film is bonded to the paper sheet in the stretched state while retaining the elastic restoring force as described above. When the shape memory PBT laminated film is applied to the lid of an instant food container, the layer structure shown in FIGS. 7 to 10 described in the above [3] (I) (3) is preferable.

  When a shape memory PBT laminated film having a PBT film having a linear mark, which will be described later, is applied to the lid of an instant food container, as shown in FIG. 20, cuts 162 and 162 should be provided on both sides of the tab portion 160. Thus, the lid 7 can be easily partially opened. When the tab portion 160 of the lid body 7 is grasped with a finger and pulled to the opposite side of the lid body 7, the lid body 7 is torn linearly from the cut edges 162 and 162, and an opening 163 is formed in the lid body 7. The flap portion 164 formed by tearing is held while being sufficiently curled. Accordingly, hot water may be poured into the opening 163 as it is.

  After pouring hot water, when the flap portion 164 is returned to its original position, the paper knurl breaks 164a and 164a are present on the outer edge of one side or both sides of the flap portion 164. The flaps 164 can no longer be lifted by engaging with the breaking parts 163a and 163a. In this case, the area of the opening 163 is not only smaller than the conventional full-opening type opening, but also because the flap 164 is locked to the opening 163, even if the container body 170 is accidentally overturned, The amount of hot water leaking is reduced. In FIG. 20, 180 indicates dry noodles.

  The container body 170 can be formed of a synthetic resin such as paper or styrene foam. In the case of a paper container main body, not only incineration is easy, but there is an advantage that gas that adversely affects the environment is not generated during incineration. In the case of a polystyrene foam container body, there is an advantage that it has excellent heat retention. The shape of the container body 170 is not limited to that shown in the figure, and can be variously changed according to the type of contents.

  21 and 22 show an example in which the shape memory PBT laminated film is used as a lid of a container for storing semi-solid foods such as jelly and pudding. When the shape memory PBT laminated film is applied to the lid of a semi-solid food container, typical examples of the layer structure are those shown in FIGS. 11 and 12 described in [3] (I) (3) above. It is. As shown in FIG. 21, in the sealed state, the lid body 7 sealed by the container 170 is flat. However, when the lid 7 is heat-sealed to the container 170, the curl shape is restored (but is apparently flat), so the lid 7 made of a shape memory PBT laminated film not having a paper sheet or aluminum foil is By being peeled from the container 170, it is strongly curled by the shape memory as shown in FIG. The container body 170 can be formed of a synthetic resin such as polypropylene or polyethylene. The shape of the container body 170 is not limited to that shown in the figure, and can be variously changed according to the type of contents. Such a lid having strong curling properties is also suitable for applications such as a lid for a portion pack such as coffee milk.

The shape memory PBT laminated film in which the tray shape described in [3] (II) is stored can be used as a food tray by cutting it for each tray shape unit length while being flat. For example, as shown in FIG. 23, instant frozen food 154 is placed on the obtained food tray 153 and then wrapped with a packaging film 155 to form a packaged product 156. As shown in FIG. 23, the packaged product 156 is heated by a microwave oven 157 or the like for eating. At this time, the food tray 153 is heated at a temperature equal to or higher than the temperature T ₁ or T ₄ for an appropriate time. Recovers the tray shape formed by the pressing die 141. In this way, when shape memory PBT laminated film is applied to food tray 153, it is almost flat in the state of packaged goods 156, so the volume is small, convenient for transportation and display, the tray shape is restored by heat treatment, and it is easy to eat There is convenience that can be.

  The packaging film 155 of the food tray 153 preferably has a number of substantially parallel line marks formed on at least one surface by a method described later. As a result, the packaging film 155 has linear tearability in one direction regardless of the orientation, and can be linearly split along a linear mark from any position. Therefore, the packaging film 155 can be easily partially opened when eating. Since such linear marks do not penetrate the film, the packaging film 155 has excellent gas barrier properties even after the linear marks are formed.

[6] Formation of linear marks on film In order to impart linear tearability to a shape memory PBT laminated film, the following method is applied to at least one of a PBT film, a rigid film, and a sealant film. It is preferable to form a large number of substantially parallel linear marks. As a result, the shape memory PBT laminated film can be easily split linearly. For example, when the shape memory PBT laminated film is used as a packaging material for the lid of an instant food container, the lid may be partially opened. It becomes possible. Such a linear mark is particularly preferably formed on a PBT film. The linear trace can be formed by sliding a continuously running film on linear trace forming means having a large number of fine protrusions. Hereinafter, a method for forming linear marks will be described in detail with reference to the drawings.

(I) Case of Forming Line Marks in Traveling Direction on Film FIG. 24 shows an example of an apparatus for forming line marks in the moving direction of the film 301. FIG. 24 shows an example in which a roll 302 (hereinafter referred to as a “pattern roll”) 302 having a large number of fine protrusions on the surface is used as a linear trace forming means, and a nozzle 303 capable of blowing air as a film pressing means. Show. The film 301 unwound from the reel 311 wound with the original film is slidably contacted with the pattern roll 302 via the nip roll 312 to form a linear mark, and the obtained linear easily tearable film is a nip roll. The film is taken up by a take-up reel 316 through 313, guide rolls 314 and 315.

  As shown in FIG. 25, the pattern roll 302 is fixed at a fixed position so that the rotation axis thereof is parallel to the width direction of the film 301, and the axial length is longer than the width of the film 301. The entire width is in sliding contact with the pattern roll.

  By providing nip rolls 312 and 313 as tension adjusting rolls before and after the pattern roll 302, tension can be applied to the film 301 running on the pattern roll 302. Further, as shown in FIG. 25, at the position where the film 301 is in sliding contact with the pattern roll 302, air with a predetermined wind pressure is blown from the opposite side of the pattern roll 302 by the nozzle 303, so that the film 301 is A uniform contact force can be applied to the surface slidably contacting 302 (hereinafter referred to as “roll slidable surface” unless otherwise specified). Thereby, uniform linear traces can be formed on the film surface. By pressing the film 301 against the pattern roll 302 using the nozzle 303, contact non-uniformity due to uneven thickness of the film 301 on the roll sliding contact surface can be alleviated.

  The pattern roll 302 is preferably rotated at a peripheral speed slower than the traveling speed of the film 301 in the direction opposite to the traveling direction of the film 301. As a result, the generation of film wrinkles can be prevented, and the shavings generated due to the formation of linear traces can be prevented from accumulating on the surface of the pattern roll 302, so that linear traces of appropriate length and depth can be formed. can do. In the present invention, the traveling speed of the film 301 is preferably 10 to 500 m / min. The peripheral speed of the pattern roll 302 (speed at which the film 301 is rotated in the direction opposite to the traveling direction of the film 301) is preferably 1 to 50 m / min.

  As the pattern roll 302, for example, those described in JP-A-2002-59487 can be used. This has a structure in which a large number of fine particles having a Mohs hardness of 5 or more are adhered to the surface of a metal roll main body by an electrodeposition method or an organic or inorganic binder. The metal roll body is made of, for example, iron or an iron alloy. The surface of the metal roll body is preferably covered with a nickel plating layer or a chromium plating layer. Examples of fine particles having a Mohs hardness of 5 or more include cemented carbide particles such as tungsten carbide, silicon carbide particles, boron carbide particles, sapphire particles, cubic boron nitride (CBN) particles, natural or synthetic diamond fine particles, and the like. Can do. In particular, synthetic diamond fine particles having high hardness, strength and the like are desirable. The particle diameter of the fine particles is appropriately selected according to the depth or width of the linear marks to be formed. In the present invention, it is desirable that the fine particles have a particle size of 10 to 100 μm and have a particle size variation of 5% or less. The degree to which the fine particles are adhered to the surface of the roll body is appropriately selected so that the interval between the linear marks to be formed becomes a desired degree. In order to obtain uniform linear marks, it is desirable that the fine particles adhere to the roll body surface by 50% or more. A specific example of the pattern roll 302 is one in which a large number of synthetic diamond fine particles are bonded and fixed to the surface of an iron roll main body through a nickel-based electrodeposition layer at an area ratio of 50% or more. The outer diameter of the pattern roll 302 is preferably 2 to 20 cm, and more preferably 3 to 10 cm.

  As the pattern roll 302, it is also possible to use a needle tooth roll in which metal needles are regularly embedded in the surface of the metal roll main body at fine intervals. In addition to the pattern roll 302, a pattern plate having a large number of fine particles having a Mohs hardness of 5 or more on the surface may be used in addition to the pattern roll 302 as the linear trace forming means.

  FIG. 26 shows a state in which the film 301 is in sliding contact with the pattern roll 302 to form linear traces. For example, the corners of at least one of the fine particles 304 on the surface of the pattern roll 302 cut into the roll sliding contact surface. As described above, the traveling speed of the film 301 is the speed around which the pattern roll 302 rotates in the reverse direction. Since it is faster than the speed, one long linear mark is formed until the corner of the cut fine particle 304 is separated from the roll sliding contact surface.

As the air blowing means, instead of a nozzle having the belt-like outlet 331 as shown in FIG. 27 (a) (the same as that shown in FIGS. 24 to 26), a plurality of air blowing means as shown in FIG. A nozzle having an outlet 331 may be used. Also, as shown in FIG. 27 (c), when compressed air is blown over the pattern roll 302 using a nozzle having a hood 332, the compressed air blown from the blowout port 331 causes the film 301 and the pattern roll 302 to Since it is difficult to diffuse before reaching the sliding contact position, the contact force between the film 301 and the pattern roll 302 on the roll sliding contact surface can be made more uniform. The pressure of the compressed air flow blown by such air blowing means is preferably 4.9 to 490 kPa (0.05 to 5 kgf / cm ² ). Thereby, the contact force between the film 301 and the pattern roll 302 on the roll sliding contact surface can be made uniform. The pressure of the compressed air flow is more preferably 9.8 to 196 kPa (0.1 to ² kgf / cm ² ). Further, the distance from the outlet 331 to the roll sliding contact surface is preferably 10 to 50 cm. The compressed air may be uniformly applied to a range covering at least the roll sliding contact surface. However, making the blower or nozzle outlet 331 larger than necessary is not preferable because the amount of compressed air required to obtain an appropriate wind pressure increases.

  Regarding the method of winding the film 301 around the pattern roll 302 fixed at a fixed position, the angle θ formed by the winding direction and the unwinding direction of the film 301 shown in FIG. 27 (c) is in the range of 60 to 170 °. It is preferable to do so. This makes it easy to adjust the length and depth of the linear trace. The angle θ is more preferably in the range of 90 to 150 °. In order to set the angle θ to a desired value, the positional relationship between the pattern roll 302 and the nip rolls 312 and 313 may be appropriately adjusted by changing the height position of the pattern roll 302 or the like. In addition, depending on how the film 301 is wound around the pattern roll 302 and the outer diameter, the tension applied to the film 301 by the nip rolls 312 and 313 and the wind pressure applied by the nozzle 303 are appropriately adjusted to achieve a desired length and depth. Try to get linear marks. In the present invention, the tension (tension per width) applied to the film by the nip rolls 312 and 313 is preferably in the range of 0.01 to 5 kgf / cm width.

  Instead of the air blowing means, a uniform contact force can be applied to the roll sliding contact surface by bringing the brush into sliding contact with the surface opposite to the roll sliding contact surface. The bristle material of the brush is in a sliding contact surface between the brush and the film 301 (hereinafter referred to as “brush sliding contact surface” unless otherwise specified), and the traveling direction of the film 301 is slower than the traveling speed of the film 301. It is preferably movable in the reverse direction. For this reason, as shown in FIG. 28, a rotating roll brush 305 in which a large number of bristle materials are arranged radially around the brush axis (rotating axis) is used as the brush, and the rotating axis is parallel to the width direction of the film 301. In this way, it is preferable that the fixed position is fixed, the length in the axial direction is longer than the width of the film 301, and the entire width of the film 301 is in sliding contact with the brush.

The outer diameter of the rotating roll brush 305 is preferably 5 to 10 cm. Regarding the bristle material 351 of the rotating roll brush 305, the bending recovery rate is preferably 70% or more, the diameter is preferably 0.1 to 1.8 mm, and the length is preferably 1 to 5 cm. The density of the bristle material 351 of the rotary roll brush 305 on the brush sliding surface is preferably 100 to 500 / cm ² . In this specification, “bending recovery rate” means a pair of chain-like loops made by crossing about 26 cm long bristle fibers, and the upper loop is fixed to the clasp, and the lower loop is attached to the lower loop. By applying a load (weight [g], which is half the fineness [denier] of the hair material fiber) for 3 minutes, a pair of pine needle-shaped samples formed at the intersections of the loops is approximately 3 cut harvested cm, from an angle opening measured after standing for 60 minutes (θ _4), the formula: is obtained by calculation in accordance with _{θ 4/180 × 100 (%} ). Although there is no restriction | limiting in particular in the shape of the front-end | tip of the hair material 351, It is preferable that it is a substantially U shape or a taper shape. The material of the hair material 351 is not particularly limited, but a synthetic resin such as polypropylene, nylon, acrylic, and polyethylene is preferable.

The rotary roll brush 305 is preferably in sliding contact with the film 301 such that the pressure on the brush sliding contact surface is 1 to 490 kPa (0.01 to 5 kgf / cm ² ). The peripheral speed of the rotating roll brush 305 (the speed at which the film 301 is rotated in the direction opposite to the traveling direction) is preferably 1 to 50 m / min.

  The length and depth of the line marks are determined so that the traveling speed of the film 301, the peripheral speed of the pattern roll 302, the particle diameter of the diamond fine particles 304, the pattern roll of the pattern roll so as to satisfy the desired degree of linear tearability. The outer diameter, the wind pressure of the nozzle 303, the pressure of the rotary roll brush 305, the tension applied by the nip rolls 312 and 313, and the like are adjusted as appropriate.

(II) In the case where oblique linear marks are formed on the film FIG. 29 shows an example of an apparatus that forms oblique linear marks with respect to the traveling direction of the film 301. The same members or parts as in FIG. 24 are given the same reference numerals. The apparatus shown in FIG. 29 includes an endless brush 307 provided with a pattern endless belt 306 to which a large number of small pattern rolls 321 are connected as a linear trace forming means, and a large number of bristle materials 371 arranged as an endless belt as a film pressing means. It has. FIG.30 (a) is a partially enlarged plan view showing a state in which the pattern endless belt 306 is rotated in the width direction of the film 301 in the apparatus shown in FIG.29, and FIG.30 (b) is shown in FIG.30 (a). It is the schematic sectional drawing seen from the D direction.

  The pattern endless belt 306 is rotated in the width direction of the film 301 as shown in FIGS. 30 (a) and 30 (b), and the small pattern roll 321 is continuously slidably contacted with the film 301, thereby moving the film 301 in the traveling direction. In contrast, oblique line marks can be formed. It is preferable to increase the number of pattern rolls 321 constituting the pattern endless belt 306 and increase the density of the pattern rolls 321. The axial length and outer diameter of the small pattern roll 321 are preferably 5 to 10 cm.

  The angle of the diagonal line trace with respect to the film traveling direction can be changed by appropriately adjusting the peripheral speed of the pattern endless belt 306 and the traveling speed of the film 301. The peripheral speed of the normal pattern endless belt 306 is set to 1 to 100 m / min. The small pattern roll 321 is rotated in the direction opposite to the traveling direction of the pattern endless belt 306 on the roll sliding contact surface. The peripheral speed is 1 to 50 m / min as in the case of the pattern roll 302 described in (I) above.

The endless brush 307 is preferably rotated so that the direction in which the bristle material 371 moves while being in sliding contact with the film 301 is opposite to the direction in which the pattern endless belt 306 is moved in sliding contact with the film 301. Therefore, the endless brush 307 and the pattern endless belt 306 are made the same with respect to the rotation direction. The length of the bristle material 371 of the endless brush 307 is preferably 4 to 8 cm. The preferable requirements regarding the bending recovery rate, the diameter, the density at the brush sliding contact surface, the tip shape, and the material of the bristle material 371 of the endless brush 307 are the same as those of the rotating roll brush 305 described in the above (I). The pressure on the brush sliding contact surface of the endless brush 307 is 1 to 490 kPa (0.01 to 5 kgf / cm ² ) as in the case of the rotary roll brush 305 described in (I) above. The pressure for sliding the endless brush 307 against the film 301 can be adjusted by rotating the height adjustment handle 373 and appropriately setting the vertical position of the endless brush 307. The peripheral speed of the endless brush 307 is preferably 1 to 50 m / min. The peripheral speed of the endless brush 307 can be adjusted by appropriately setting the rotational speed of the motor 374.

  The pattern endless belt 306 and the endless brush 307 preferably have a length in the traveling direction longer than the width of the film 301 so that the entire width of the film 301 is in sliding contact with the pattern endless belt 306 and the endless brush 307.

  FIG. 31 shows another example of an apparatus for forming linear traces oblique to the traveling direction of the film 301. The same members or parts as in FIG. 24 are given the same reference numerals. The apparatus shown in FIG. 31 has a roll train 308a in which a large number of small pattern rolls 322a are mounted in parallel to a guide rail 381a (support) as shown in FIG. A pattern train 322b is provided with a roll train 308b that is attached in parallel to a guide rail 381b (support).

  The support shafts 391a and 391b that support the pattern rolls 322a and 322b are movable up and down, and the roll trains 308a and 308b can move linearly in the width direction of the film 301 along the guide rails 381a and 381b, respectively. The roll trains 308a and 308b can move independently in the width direction of the film 301 by the guide means including the support shafts 391a and 391b which can be moved up and down and the guide rails 381a and 381b. For this reason, the roll trains 308a and 308b are moved while being in sliding contact with the film 301 from one end side to the other end side of the film 301, and after moving to the other end side, the cycle is separated from the film 301 and returned to the original position. By repeating the process, the movement of the roll trains 308a and 308b is controlled so that one of the roll trains always comes into sliding contact with the entire width of the film 301, thereby forming a linear trace that is oblique with respect to the traveling direction of the film. be able to. The guide means may be configured such that the guide rails 381a and 381b can be raised and lowered instead of preventing the support shafts 391a and 391b from being raised and lowered with respect to the guide rails 381a and 381b.

  The pattern rolls 322a and 322b may have an axial length and an outer diameter of about 5 to 10 cm. The gap between the pattern rolls of the pattern rolls 322a and 322b is preferably at least narrower than the roll width of the pattern roll to increase the density of the pattern roll. Each length of the roll trains 308 a and 308 b is longer than the width of the film 301.

  In the apparatus shown in FIG. 31, the same endless brushes 307a and 307b as those of the apparatus shown in FIG. 29 are provided as film pressing means in parallel to the roll trains 308a and 308b with the film 301 in between. . However, the support members 372 and 372 that support the endless brushes 307a and 307b can be raised and lowered. For this reason, by controlling the elevation so that the endless brush 307a is in sliding contact with the film 301 simultaneously with the roll train 308a, and by controlling the elevation so that the endless brush 307b is in sliding contact with the film 301 simultaneously with the roll train 308b. A constant contact force can always be applied to the roll sliding contact surface.

  The endless brushes 307a and 307b are preferably rotated so that the direction in which the bristle material moves while being in sliding contact with the film 301 is opposite to the direction in which the roll trains 308a and 308b move while being in sliding contact with the film 301. Bend recovery rate, diameter, length, density at the brush sliding contact surface of the endless brushes 307a and 307b, preferable requirements regarding the tip shape and material, and pressure at the brush sliding contact surface of the endless brushes 307a and 307b, endless brush 307a The peripheral speed of 307b is the same as that of the endless brush 307 included in the apparatus shown in FIG.

  The angle of the linear traces in the oblique direction with respect to the film traveling direction can be changed by appropriately adjusting the speed at which the roll trains 308a and 308b are brought into sliding contact with the traveling speed of the film 301. The pattern rolls 322a and 322b are rotated in the opposite direction to the progress of the roll trains 308a and 308b on the roll sliding contact surface. The peripheral speed may be the same as that of the pattern roll 302 described in (I) above.

  FIG. 33 (a) and FIG. 33 (b) show another example of an apparatus for forming linear traces oblique to the traveling direction of the film 301. FIG. In this example, two pattern rolls 323 a and 323 b having an axial length longer than the width of the film 301 are installed in parallel in the front-rear direction in the traveling direction of the film 301. The axial length of the pattern rolls 323a and 323b is preferably at least twice the width of the film 301.

  The support shafts 392a and 392b that support the pattern rolls 323a and 323b are movable up and down, and the pattern rolls 323a and 323b can move linearly in the width direction of the film 301 along the guide rails 382a and 382b, respectively. The pattern rolls 323a and 323b can be independently moved in the width direction of the film 301 by the guide means including the vertically movable 392a and 392b and the guide rails 382a and 382b. Therefore, the pattern rolls 323a and 323b are moved from one end side to the other end side of the film 301 while being in sliding contact with the film 301, and after moving to the other end side, the cycle is separated from the film 301 and returned to the original position. In this case, by controlling the movement of the pattern rolls 323a and 323b so that one of the pattern rolls always contacts the entire width of the film 301, linear traces oblique to the film traveling direction are controlled. Can be formed. The angle of the linear traces in the oblique direction with respect to the film traveling direction can be changed by appropriately adjusting the speed at which the pattern rolls 323a and 323b slide and the traveling speed of the film 301.

  In the apparatus shown in FIG. 33, endless brushes 307a and 307b that can be moved up and down as the film pressing means are provided in parallel to the pattern rolls 323a and 323b with the film 301 in between, respectively, as in the apparatus shown in FIG. Is provided.

  In the apparatus shown in FIGS. 29 to 33, the endless brush is provided as the film pressing means, but the air blowing means described in (I) above may be provided.

(III) Forming widthwise linear marks on a film FIG. 34 shows an example of an apparatus for forming widthwise linear marks on a film 301. The same members or parts as in FIG. 29 are given the same reference numerals. The apparatus shown in FIG. 34 is the same as the apparatus shown in FIGS. 29 and 30 except that the pattern endless belt 306 is provided obliquely with respect to the film traveling direction (the endless brush is not shown). . Using the apparatus configured as shown in FIG. 34, by appropriately setting the operating conditions such as the traveling speed of the film 301, the angle of the pattern endless belt 306 with respect to the traveling direction of the film 301, the peripheral speed of the pattern endless belt 306, A linear mark in the width direction of the film 301 can be formed.

  FIG. 35 shows another example of an apparatus for forming a linear mark in the width direction on the film 301. In this example, the pattern endless belt 306a connected to a large number of small pattern rolls 321a and the pattern endless belt 306b connected to a large number of small pattern rolls 321b are symmetrical with respect to the center line 317 of the film 301. And obliquely with respect to the traveling direction of the film. As the film pressing means, the same endless brush as described with respect to the apparatus shown in FIG. 29 is preferably provided in parallel with the pattern endless belts 306a and 306b with the film 301 in between (not shown).

  Using the apparatus having the configuration shown in FIG. 35, the operating conditions such as the traveling speed of the film 301, the angle of the pattern endless belts 306a and 306b with respect to the center line 317 of the film 301, the peripheral speed of the pattern endless belts 306a and 306b, etc. By setting, a linear mark in the width direction of the film 301 can be formed.

  FIG. 36 shows another example of an apparatus for forming linear traces in the width direction of the film 301. The apparatus shown in FIG. 36 is the same as the apparatus shown in FIG. 32 except that the roll trains 308a and 308b shown in FIG. 32 are provided obliquely with respect to the width direction of the film 301 (the endless brush is not shown). ) Using the apparatus shown in FIG. 36, by appropriately setting the operating conditions such as the traveling speed of the film 301, the angle of the roll trains 308a and 308b with respect to the traveling direction of the film 301, and the sliding contact speed of the roll trains 308a and 308b. Further, linear traces in the width direction of the film 301 can be formed.

  FIG. 37 (a) and FIG. 37 (b) show another example of an apparatus for forming linear marks in the width direction of the film 301. FIG. FIG. 37 (b) shows the left side of the device shown in FIG. 37 (a) (as viewed from the direction F in FIG. 37 (a)). In this example, two pattern rolls 324a and 324b having an axial direction inclined with respect to the traveling direction of the film 301 are provided. The axial length of the pattern rolls 324a and 324b is preferably at least twice the width of the film 301.

  The support shafts 393a and 393b that support the pattern rolls 324a and 324b are movable up and down, and the pattern rolls 324a and 324b maintain a predetermined angle with respect to the center line 317 of the film 301 along the guide rails 383a and 383b, respectively. While moving linearly. The pattern rolls 324a and 324b can be independently moved while maintaining a predetermined angle with respect to the center line 317 of the film 301 by the guide means comprising the vertically movable 393a and 393b and the guide rails 383a and 383b. As for the axial length, the pattern roll 324b is longer than the pattern roll 324a, so that the pattern rolls 324a and 324b can pass each other when traveling in opposite directions. Therefore, the pattern rolls 324a and 324b are moved from one end side to the other end side of the film 301 while being in sliding contact with the film 301, and after moving to the other end side, the cycle is separated from the film 301 and returned to the original position. In this case, by controlling the movement of the pattern rolls 324a and 324b so that one of the pattern rolls is always in sliding contact with the entire width of the film 301, the linear shape in the width direction with respect to the traveling direction of the film Scratches can be formed.

  As the film pressing means, as shown in FIG. 37 (b), rotary roll brushes 305a and 305b supported on the support shafts 352a and 352b that can be moved up and down and linearly moved are provided, and the films of the pattern rolls 383a and 383b are provided. It is made to move according to the movement of the roll sliding contact surface with 301. Further, by making one of the rotating roll brushes 305a and 305b longer than the other with respect to the axial length, the rotating roll brushes 305a and 305b can pass each other when traveling in the opposite directions. As a result, a contact force can always be applied to the roll sliding contact surface of the pattern roll 383a or 383b with the film 301. The preferable requirements regarding the bending recovery rate, diameter, length, density at the brush sliding contact surface, tip shape and material of the bristle material 351 of the rotating roll brushes 305a and 305b are the same as those of the rotating roll brush 305 described in (I) above. The same.

  In the apparatus shown in FIGS. 34 to 37, linear traces oblique to the traveling direction of the film 301 can also be formed by appropriately changing the setting of operating conditions and the like. 34 to 37, the endless brush is provided as the film pressing means, but the air blowing means described in (I) above may be provided.

  In the linearly tearable film produced by the method described above, the depth of the linear trace is preferably 1 to 40% of the film thickness. Thereby, both film strength and good linear tearability can be achieved. The depth of the linear traces is preferably 0.1 to 10 μm, the width is preferably 0.1 to 10 μm, and the interval between the linear traces is preferably 10 to 200 μm.

[7] Micro-hole processing in film In order to impart linear tearability to the shape memory PBT laminated film, fine through-holes are formed on the entire surface of at least one of the PBT film, rigid film, and sealant film. Also good. The fine through-hole is particularly preferably formed in the sealant film. The micropores preferably have an average opening diameter of 0.5 to 100 μm and a distribution density of about 500 holes / cm ² or more. If the distribution density of the micropores is less than about 500 holes / cm ² , the easy tearability is insufficient. The upper limit of the fine pore density is not particularly limited as long as it is technically possible.

  In order to form micropores in the film, for example, methods disclosed in Japanese Patent No. 2071842 and Japanese Patent Application Laid-Open No. 2002-059487 can be employed. For example, when the method disclosed in Japanese Patent No. 2071842 is used, a first roll in which a large number of particles having a Mohs hardness of 5 or more having sharp corners adhere to the surface (similar to the pattern roll 302 described in [7] above) And a second roll having a smooth surface so that the pressing force applied to the film passing between the rolls is uniform over the entire film surface in contact with each roll. By adjusting, many fine pores can be formed in the film at sharp corners of many particles on the surface of the first roll. As the second roll, for example, an iron-based roll, an iron-based roll having a surface plated with Ni, Cr, or the like, a stainless-based roll, a special steel roll, or the like can be used.

[8] Deposition of ceramic or metal For the purpose of improving the gas barrier property of the shape memory PBT laminated film, the PBT film can be vapor-deposited with metal, ceramic or the like, or coated with a resin. Specific examples of the ceramic to be deposited include silica and alumina. Vapor deposition of metal, ceramic, etc. can be performed by a known method.

[9] Functional polybutylene terephthalate film By forming the linear marks and / or micropores described below in the PBT film of the present invention, a more excellent function as a packaging material can be imparted.

(I) Linearly tearable polybutylene terephthalate film In the linearly tearable PBT film, a number of substantially parallel linear marks were formed on at least one surface of the PBT film according to the method described in [6] above. Is. For this reason, it has the linear tearability to one direction irrespective of the orientation of a raw material film, and can be split linearly along a linear trace from arbitrary positions. If a packaging bag is manufactured using a linear easily tearable PBT film, it can be opened in a strip shape without a taper while maintaining a certain width. Moreover, since the linear easily tearable PBT film does not penetrate through the linear marks, it has excellent gas barrier properties.

  The linear scar depth of the linear easily tearable PBT film is preferably 1 to 40% of the film thickness. Thereby, both film strength and good linear tearability can be achieved. The depth of the linear traces is preferably 0.1 to 10 μm, the width is preferably 0.1 to 10 μm, and the interval between the linear traces is preferably 10 to 200 μm.

  The thickness of the linear easily tearable PBT film is preferably about 5 to 50 μm, more preferably about 10 to 20 μm, for example, about 12 μm. If it is about 5-50 micrometers in thickness, while having sufficient fragrance retention property and gas-barrier property, glossiness and a printing characteristic are also favorable.

  Moreover, a metal, ceramics, etc. can be vapor-deposited on a linear easily tearable PBT film, or resin can be coated. As a specific example, silica, alumina or the like can be deposited. By vapor-depositing such a ceramic, the gas barrier property of the linear easily tearable PBT film is improved. Vapor deposition of metal, ceramic, etc. can be performed by a known method. Metals, ceramics, and the like may be deposited on either the line-formed surface or the non-formed surface of the film. Since the PBT film obtained by the production method of the present invention has a low thermal shrinkage rate, the deposited layer is stable when the deposited layer is formed.

  Further, the linear easily tearable PBT film can be a laminated film having a layer made of general-purpose polyolefin and special polyolefin. Specifically, low density polyethylene (LDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), unstretched polypropylene (CPP), linear low density polyethylene (L-LDPE), ultra low density polyethylene ( VLDPE), ethylene / vinyl acetate copolymer (EVA), ethylene / acrylic acid copolymer (EAA), ethylene / methacrylic acid copolymer (EMAA), ethylene / ethyl acrylate copolymer (EEA), ethylene / methyl Methacrylate copolymer (EMMA), ethylene / methyl acrylate copolymer (EMA), ionomer (IO) and the like. Further, for the purpose of improving moisture resistance and gas barrier properties, it is preferable to provide an intermediate layer with an aluminum foil, a silica-deposited polyethylene terephthalate film, an alumina-deposited polyethylene terephthalate film, or the like.

  In addition, when making a laminated film, it is manufactured by laminating with another film after processing to provide a linear mark described later on the PBT film, or by laminating with another film via the intermediate layer. May be. Lamination is performed by extrusion lamination with an adhesive layer provided between the layers. A polyethylene layer is preferred as the adhesive layer.

  As an application of the linear easily tearable PBT film in which linear marks are formed in the film traveling direction (longitudinal direction), there is a packaging bag for stick-shaped confectionery. By using a linear easily tearable PBT film having linear traces in the longitudinal direction, it can be opened in a strip shape without a taper while maintaining a certain width, so that the candy is not damaged. In addition, packaging using OPP film such as rice balls has cut tape (tear tape) attached to the opening width, but linear easily tearable PBT film with linear marks formed in the longitudinal direction has an opening width. Tear tape is not required because it can be maintained and opened.

  As an application of the linear easily tearable PBT film in which linear traces oblique to the traveling direction of the film are formed, there are packaging bags for powdery medicinal use, seasoning for lunch box, and the like. By using a linear easily tearable PBT film having linear traces in an oblique direction, the corners of the packaging bag can be easily broken obliquely.

  As an application of a linear easily tearable PBT film in which linear marks are formed in the width direction (lateral direction) of the film, there is a stick-shaped packaging bag for powdered instant foods. By using a linear easily tearable PBT film having a linear trace in the lateral direction, a stick-shaped packaging bag whose demand is increasing can be manufactured at a low cost.

  A number of fine through-holes and / or non-through-holes can be uniformly formed in the linear easily tearable PBT film according to the method described in [7] above. Thereby, not only the linear tearability is further improved, but also easy tearability can be imparted in directions other than the linear trace direction.

(II) Porous polybutylene terephthalate film A porous PBT film is obtained by uniformly forming a large number of fine through holes and / or non-through holes in a PBT film according to the method described in [7] above. For this reason, the porous PBT film has high twist retention, does not cause tearing during twisting, has good twisting properties, and is easily tearable. The micropores preferably have an average opening diameter of 0.5 to 100 μm and a density of about 500 holes / cm ² or more. If the density of the micropores is less than about 500 holes / cm ² , the twist retention is insufficient.

  Porous PBT film maintains its practical properties without losing the excellent properties of PBT film, such as heat resistance, fragrance retention, and water resistance, and is useful as a packaging material with good tearing and twisting properties. is there. However, when a gas barrier property is required for a packaging material made of a porous PBT film, a material having no fine pores is used.

  As mentioned above, although this invention was demonstrated with reference to drawings, this invention is not limited to them, A various change can be added unless the meaning of this invention is changed.

  The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Example 1
A PBT film was produced by an air-cooled inflation molding method using the apparatus shown in FIG. PBT resin (trade name “Toraycon 1200S”, manufactured by Toray Industries, Inc., melting point: 220 ° C., intrinsic viscosity: 1.2) was charged into a single screw extruder (screw diameter: 50 mm, extrusion rate: 50 kg / hr), 210 The mixture was melt kneaded at 0 ° C. and a molten resin was prepared in an extruder. Subsequently, the molten resin was extruded from the outlet of the extruder at an extrusion resin temperature of 210 ° C. and an extrusion resin pressure of 11.8 MPa (120 kgf / cm ² ), and from the die head (die diameter: 150 mm, die lip gap: 0.9 mm). A tube of molten resin was extruded. The extruded molten resin tube is expanded at a blow-up ratio of 3.6, and (1) the bubble neck is gradually cooled to 185 ° C by blowing warm air (30 ° C) from the first hot air blowing device. , (2) Slowly cool the bubble expansion to 160 ° C by blowing hot air (30 ° C) from the second hot air blowing device, and (3) Hot air (50 ° C) from the third hot air blowing device The frost line region was gradually cooled to 125 ° C. by spraying (4), and the bubble region was withdrawn at 20 m / min while maintaining the bubble region at 100 ° C. to produce a PBT film. The cylindrical net surrounding the bubble region is made of nylon, and the acrylic resin cylindrical partition wall is provided with two hot air outlets on the upper side, and a bar heater on the inside. A rectifying plate having a hole area ratio of 60% was provided on the inside.

Example 2
A PBT film was produced in the same manner as in Example 1 except that the extrusion resin temperature was 205 ° C. and the extrusion resin pressure was 12.7 MPa (130 kgf / cm ² ).

Example 3
A PBT film was produced in the same manner as in Example 1 except that the extrusion resin temperature was 215 ° C. and the extrusion resin pressure was 10.8 MPa (110 kgf / cm ² ).

Comparative Example 1
A PBT film was produced in the same manner as in Example 1 except that the extrusion resin temperature was 230 ° C. and the extrusion resin pressure was 8.8 MPa (90 kgf / cm ² ).

Comparative Example 2
A PBT film was produced in the same manner as in Comparative Example 1 except that the current plate was not used.

The physical properties of the PBT films obtained in Examples 1 to 3 and Comparative Examples 1 and 2 were measured by the following method. The results are shown in Table 1.
Average film thickness: A value obtained by measuring a total of 6 film thicknesses by measuring 2 thicknesses at the center and both ends in the width direction of the sheet with a contact thickness meter was averaged.
-Film thickness variation: The thickness of the central part and both ends in the width direction of the PBT film was measured at two points, respectively, for a total of six points, and was determined from the difference between the maximum value and the minimum value.
・ Tensile rupture strength: Measure the tensile rupture strength of strip-shaped test pieces with a width of 10 mm according to ASTM D882.
-Thermal shrinkage: The shrinkage of MD and TD was measured when the PBT film was exposed at 175 ° C for 10 minutes.
-Crystallinity: measured by X-ray method.

  As shown in Table 1, the PBT films of Examples 1 to 3 produced by the method of the present invention have high crystallinity, excellent film thickness uniformity and tensile breaking strength, and low heat shrinkage. I understand. In Examples 1 to 3, during the production of the PBT film, the bubbles did not roll and were stable throughout. On the other hand, in Comparative Example 1, since the extrusion resin temperature was set to be equal to or higher than the melting point of the PBT resin, the crystallinity was low and the tensile strength at break was inferior. In Comparative Example 2, since no rectifying plate was used, the bubbles tumbled during film production and were unstable.

It is the schematic which shows an example of the apparatus which manufactures the polybutylene terephthalate film by the air cooling inflation molding method of this invention. It is a schematic sectional drawing which shows an example of the apparatus which cools a bubble slowly. 3A is a plan view showing an example of the current plate, FIG. 3B is a plan view showing another example of the current plate, and FIG. 3C is still another example of the current plate. FIG. FIG. 4 (a) is a partial cross-sectional schematic side view showing an example of an apparatus for sequentially biaxially cold-drawing a PBT film produced by an air-cooled inflation molding method, and FIG. 4 (b) is an outline of the apparatus of FIG. 4 (a). It is a top view. FIG. 5 (a) is a schematic side view showing an example of an apparatus for cold-drawing a PBT film produced by an air-cooled inflation molding method in the longitudinal direction, and FIG. 5 (b) shows a PBT film produced by an air-cooled inflation molding method in the longitudinal direction. FIG. 5C is a schematic side view showing still another example of an apparatus for cold-drawing a PBT film produced by an air-cooled inflation molding method in the longitudinal direction. FIG. It is the schematic which shows an example of the apparatus which cold-draws the PBT film manufactured by the air cooling inflation method by an in-line system. It is sectional drawing which shows the layer structural example of a shape memory PBT film laminated body. It is sectional drawing which shows another layer structural example of a shape memory PBT laminated | multilayer film. It is sectional drawing which shows another example of a layer structure of a shape memory PBT laminated film. It is sectional drawing which shows another example of a layer structure of a shape memory PBT laminated film. It is sectional drawing which shows another example of a layer structure of a shape memory PBT laminated film. It is sectional drawing which shows another example of a layer structure of a shape memory PBT laminated film. It is the schematic which shows an example of the apparatus which manufactures a shape memory PBT laminated film. It is the schematic which shows another example of the apparatus which manufactures a shape memory PBT laminated film. It is the schematic which shows another example of the apparatus which manufactures a shape memory PBT laminated film. It is the schematic which shows another example of the apparatus which manufactures a shape memory PBT laminated film. It is the schematic which shows another example of the apparatus which manufactures a shape memory PBT laminated film. It is the schematic which shows an example of the apparatus which manufactures the container with a cover body. FIG. 3 is a perspective view showing an instant food container in which a lid made of the shape memory PBT laminated film of the present invention is opened for pouring hot water. FIG. 3 is a perspective view showing an instant food container in which a lid made of the shape memory PBT laminated film of the present invention is partially broken and opened for pouring. It is a perspective view which shows the example which used the container with a lid of this invention as a container for semi-solid food. FIG. 22 is a perspective view showing a state where the container with a lid of FIG. 21 is opened. It is the schematic which shows a mode that the shape memory PBT laminated | multilayer film used for the food tray recovers shape. It is the schematic which shows an example of the apparatus which forms a linear trace in the advancing direction of a film. FIG. 25 is a partially enlarged view showing a state in which compressed air is blown onto the surface of the film shown in FIG. 24 in sliding contact with the pattern roll. FIG. 25 is a partially enlarged cross-sectional view showing a state in which the film is in sliding contact with the pattern roll in the apparatus shown in FIG. FIG.27 (a) is a front view and a right side view showing an example of a nozzle, FIG.27 (b) is a front view and a right side view showing another example of the nozzle, and FIG.27 (c) is a hood. It is the schematic which shows a mode that compressed air is sprayed on a pattern roll using the nozzle which has. It is the schematic which shows another example of the apparatus which forms a linear trace in the advancing direction of a film. It is a perspective view which shows an example of the apparatus which forms the diagonal trace which is diagonal with respect to the advancing direction of a film. FIG.30 (a) is a partially enlarged plan view showing a state in which the film is in sliding contact with the pattern endless belt in the apparatus shown in FIG.29, and FIG.30 (b) is a schematic view seen from the D direction in FIG.30 (a). It is sectional drawing. It is the schematic which shows another example of the apparatus which forms the diagonal trace which is diagonal with respect to the advancing direction of a film. FIG. 32 is a partially enlarged plan view showing a state where the film is in sliding contact with the roll train in the apparatus shown in FIG. FIG. 33 (a) is a partially enlarged plan view showing another example of an apparatus for forming linear traces oblique to the traveling direction of the film, and FIG. 33 (b) is viewed from the E direction in FIG. 33 (a). FIG. It is the elements on larger scale which show an example of the apparatus which forms the linear trace of the width direction with respect to the advancing direction of a film. It is a partial enlarged plan view which shows another example of the apparatus which forms the linear trace of the width direction with respect to the advancing direction of a film. It is a partial enlarged plan view which shows another example of the apparatus which forms the linear trace of the width direction with respect to the advancing direction of a film. FIG. 37 (a) is a partially enlarged plan view showing another example of an apparatus for forming linear traces in the width direction with respect to the film traveling direction, and FIG. 37 (b) is an F direction in FIG. 37 (a). It is the schematic seen from.

Explanation of symbols

1 ... Inflation die
10 ... Die head
100 ・ ・ ・ Ring orifice
11 ... Weld part
110 ・ ・ ・ Extruder outlet
111 ・ ・ ・ Die head entrance
112 ・ ・ ・ Temperature detector
12 ... Extruder
120 ... Screen pack
121 ... Pressure detector
13 ... Tipper nip roll
14 ... take-up reel
15 ... Insulation
16 ... Guide roll
17 ... Nip roll
18 ... Cutter
19 ... Heater 2, 2 '... Inflation PBT film
20 ... First hot air blowing device
21 ... Second hot air blowing device
22 ・ ・ ・ Third hot air blowing device
23 ... Bulkhead
230 ・ ・ ・ Hot air outlet
231 ・ ・ ・ Side wall side
232 ・ ・ ・ Bump top surface
24 ・ ・ ・ Heating means
25 ... Cylindrical net
26 ... Air injection pipe
27 ... cooling tower
28 ... Rectifying plate 3 ... Bubble
31 ... Neck
32 ... Expanded part
33 ・ ・ ・ Bubble area
34 ... Frost line 4 ... Longitudinal extension
41 ... Slow drive roll
42 ... High-speed drive roll
43 ... Heating roll (preheating roll)
44 ・ ・ ・ Cooling roll
45 ・ ・ ・ Heating slow drive roll
46 ... Cooling speed drive roll 5 ... Tenter (transverse section)
51 ・ ・ ・ Film clip roller
52 ... Gear
53 ・ ・ ・ Hot air introduction hole
54 ... Hood 6 ... Edge / position control device
61 ... Guide roll
62 ... Connection shaft
63 ... Sensor 7 ... Shape memory polybutylene terephthalate film laminate
71 ・ ・ ・ Paper sheet
72 ・ ・ ・ Sealant film layer
73 ... Polyethylene (layer) (I)
73 '・ ・ ・ Polyethylene (layer) (II)
73 '' ・ ・ ・ Polyethylene (layer) (III)
74 ・ ・ ・ Adhesive (layer) (I)
74 '・ ・ ・ Adhesive (layer) (II)
74 '' ・ ・ ・ Adhesive (layer) (III)
75 ・ ・ ・ Rigid film layer
76 ... Light-shielding ink layer
77 ・ ・ ・ Metal foil layer
78 ... Curl laminated film
80 ... Original film
81 ... Original film of other film or film laminate
82 ... Other films or film laminates
83 ... Rolled film
84 ... Laminated film
85 ... Shaped laminate
86 ... Original film for coating
87 ... Coating film
88 ... Wound film made of PBT film laminate after punching
130 ... Guide roll
131 ・ ・ ・ Gravure roll
132 ・ ・ ・ Drying furnace
133, 133 '・ ・ ・ Pressure adjustment roll
134 ・ ・ ・ Die
135 ・ ・ ・ Cooling roll
135 '・ ・ ・ Rubber roll
136 ・ ・ ・ Cold processing roll
137,137 '・ ・ ・ Nip roll
138 ... Heater
139: Cooling roll
140 ... Heating roll
141 ・ ・ ・ Push type
142 ... Heating roll
143 ... Cooling device
144 ・ ・ ・ Take-up roll
145 ... Heating roll
145 '・ ・ ・ Abutment roll
146,146 '... Nip roll
147 ... Heater
148 ... Deflection prevention roll
149 ... Guide roll
150 ... Lid sealing device
151 ・ ・ ・ Seal head
152 ... Contact roll
153 ... Food tray
154 ... Instant frozen food
155 ... Packaging film
156 ・ ・ ・ Packed products
157 ... Microwave oven
160 ... Tab part
161 ... mark
162 ... Cut
163 ... Opening
163a ・ ・ ・ Fracture part
164 ・ ・ ・ Flap part
164a ・ ・ ・ Fracture part
170 ... container
180 ・ ・ ・ Dried noodles
301 ・ ・ ・ Film
302,321,321a, 321b, 322,322a, 322b, 323a, 323b, 324a, 324b ... Pattern roll
303 ・ ・ ・ Blower
331 ... Outlet
332 ... Food
304 ・ ・ ・ Diamond fine particles
305, 305a, 305b ... Roll brush
351 ... Hair material
306, 306a, 306b ... Pattern endless belt
307, 307a, 307b ・ ・ ・ Endless brush
371 ... Hair material
308a, 308b ・ ・ ・ Roll train
311 ・ ・ ・ Reel
312,313 ・ ・ ・ Nip roll
314, 315 ... Guide roll
316 ... take-up reel
317 ... Center line of film
352a, 352b ... support shaft
372 ... Support member
373 ・ ・ ・ Height adjustment handle
374 ... Motor
381a, 381b ・ ・ ・ Guide rail
382a, 382b ・ ・ ・ Guide rail
383a, 383b ・ ・ ・ Guide rail
391a, 391b ... Support shaft
392a, 392b ... support shaft
393a, 393b ... support shaft

Claims (22)

A method for producing a polybutylene terephthalate film of molten polybutylene terephthalate resin extruded from a circular die tube by air-cooling inflation method that form a bubble is inflated by injection of air, the extruded resin temperature (of the polybutylene terephthalate resin ( Melting point−15 ° C. ) to (the melting point−5 ° C. ) , the extrusion resin pressure is set to 8.3 to 13.7 MPa, and the neck of the bubble is gradually increased to the melting point−40 ° C. to the melting point−25 ° C. Cool, gradually cool the expanded portion of the bubble to (the melting point −70 ° C.) to (the melting point −40 ° C.), and the frost line region of the bubble (the melting point −130 ° C.) to (the melting point −90 ° C.) ) to gradually cooled, this is maintained at a temperature above the bubble area than the frost line (the glass transition temperature Tg of the polybutylene terephthalate resin) ultra to (Tg + 65 ° C.) Wherein the. 2. The method for producing a polybutylene terephthalate film according to claim 1, wherein the expansion part of the bubble is non-cooled by gradually cooling the expansion part of the bubble to (the melting point−70 ° C.) to (the melting point−40 ° C.). A method characterized by holding in a crystalline state. The method for producing a polybutylene terephthalate film according to claim 1 or 2 , wherein the intrinsic viscosity of the polybutylene terephthalate resin is 0.8 to 1.5. The method for producing a polybutylene terephthalate film according to any one of claims 1 to 3 , wherein the polybutylene terephthalate resin contains 5 to 15% by mass of a polyolefin and / or an elastomer. In the manufacturing method of the polybutylene terephthalate film in any one of Claims 1-4 , the clearance gap of the said cyclic | annular die is 0.8-1.2 mm, die | dye diameter is 120-250 mm, blowup ratio is 2.0. A method characterized by being -4.0. In the manufacturing method of the polybutylene terephthalate film in any one of Claims 1-5 , (1) By blowing a warm air from the 1st warm air blowing apparatus provided in the vicinity of the said cyclic | annular die, the bubble of said gradually cooled neck portion (the melting point -40 ° C.) ~ (the melting point -25 ℃), (2) ejecting the hot air from the second temperature air blowing out device provided above the first temperature air blowing out device by gradually cooled inflation portion of the bubble (the melting point -70 ° C.) ~ (the melting point -40 ° C.), (3) a third temperature air blowing provided above the second temperature air blowing out device by jetting warm air from the detection device, gradually cooled frost line region of the bubble (the melting point -130 ° C.) ~ (the melting point -90 ° C.), (4) the Frost line above the bubble area The bubble region is surrounded by an external wall with a gap provided around the periphery. With blocking of the gas, the first-warm air ejected from the third temperature air blowing out device blown along the outer surface of the bubble area, and by a heating means provided in the partition wall, the bubble area (the polybutylene A method characterized in that the glass transition temperature Tg) of the terephthalate resin is maintained at a temperature exceeding (Tg + 65 ° C.) . In the manufacturing method of the polybutylene terephthalate film of Claim 6 , while providing a some hot air discharge port in the said partition, and providing a baffle plate inside the said partition, said 1st-3rd warm air blowing apparatus A method characterized by rectifying the warm air ejected from the air. In the manufacturing method of the polybutylene terephthalate film of Claim 6 or 7 , the temperature of the warm air ejected from said 1st and 2nd warm air blowing apparatus is 25-50 degreeC, From said 3rd warm air blowing apparatus The method is characterized in that the temperature of the hot air to be ejected is ( Tg + 65 ° C. ) exceeding ( the glass transition temperature Tg of the polybutylene terephthalate resin ) . A polybutylene terephthalate film obtained by the production method according to any one of claims 1-8, a variation ±. 1 to ± 3 [mu] m of thickness in the average thickness 8 to 30 m, a crystallinity of 35 A polybutylene terephthalate film having a thermal shrinkage ratio of 0.4% or less in a longitudinal direction and a width direction when exposed at 175 ° C. for 10 minutes . (a) an annular die that extrudes a molten polybutylene terephthalate resin into a tube shape at a temperature of (the melting point of the polybutylene terephthalate resin −15 ° C.) to (the melting point −5 ° C.) and a pressure of 8.3 to 13.7 MPa; ) Means for injecting air into the obtained polybutylene terephthalate tube to form bubbles; (c) provided near the annular die, and the neck portion of the bubbles is formed by blowing hot air (the melting point) A first hot air blowing device that gradually cools to −40 ° C.) to (the melting point −25 ° C.), and (d) provided above the first hot air blowing device, A second hot air blowing device that gradually cools the expansion portion to (the melting point −70 ° C.) to (the melting point −40 ° C.) ; and (e) a hot air blown out provided above the second hot air blowing device the frost line region of the bubble by (the melting point 130 ° C.) and the third temperature air blowing out device for slow cooling to (the melting point -90 ° C.), provided around the (f) the above third temperature air blowing out device, and above the bubble area than the frost line A partition wall for blocking the bubble area from the external atmosphere and blowing up the hot air blown from the first to third hot air blowing devices along the outer surface of the bubble area, and the partition wall is heated. have a means and a plurality of hot air outlet, characterized in that to hold the bubble region to a temperature of (the glass transition temperature Tg of the polybutylene terephthalate resin) ultra to (Tg + 65 ° C.) device. 11. The apparatus for producing a polybutylene terephthalate film according to claim 10 , wherein a current plate is provided inside the partition wall. 12. The apparatus for producing a polybutylene terephthalate film according to claim 10 , wherein the bubble expansion portion is gradually cooled in an amorphous state by the hot air blown from the second hot air blowing device. . (a) Obtained by the manufacturing method according to any one of claims 1 to 8 , the variation in film thickness at an average film thickness of 8 to 30 μm is ± 1 to ± 3 μm, and the crystallinity is 35 to 40%. Selected from the group consisting of a polybutylene terephthalate film having a thermal shrinkage of 0.4% or less when exposed at 175 ° C. for 10 minutes , and (b) a paper sheet, other resin film, and a metal foil. had at least one kind, the polybutylene terephthalate temperatures T ₁ below the glass transition temperature the film is shaped processed first shape, deformed into a second shape at temperature T ₂ exceeding the glass transition temperature processed, then the being secured to said second shape by being cooled to a temperature below the glass transition temperature T _3, by exposure to the temperature above T _1, said from said second shape first characterized in that return to one shape Jo storage polybutylene terephthalate laminate film. The shape memory polybutylene terephthalate laminated film according to claim 13, wherein the temperature T ₁ Is 35 ° C. or less, and the temperature T ₂ Is above 45 ° C. and below 65 ° C., and the temperature T _Three Is a shape memory polybutylene terephthalate laminated film characterized by being 15 to 25 ° C. The shape memory polybutylene terephthalate laminated film according to claim 13 or 14, wherein the temperature T ₁ Is a shape memory polybutylene terephthalate laminated film characterized by being 15 to 25 ° C. (a) Obtained by the manufacturing method according to any one of claims 1 to 8 , the variation in film thickness at an average film thickness of 8 to 30 μm is ± 1 to ± 3 μm, and the crystallinity is 35 to 40%. Selected from the group consisting of a polybutylene terephthalate film having a thermal shrinkage of 0.4% or less when exposed at 175 ° C. for 10 minutes , and (b) a paper sheet, other resin film, and a metal foil. and at least one kind was, the polybutylene terephthalate temperature T ₄ lower than the glass transition temperature super-melting point of the film is shaped processed first shape, is cooled to a temperature T ₅ follows the glass transition temperature secured to said first shape, said is a glass transition temperature super-said temperature T ₆ below the temperature T ₄ deforming a second shape, to be cooled to a temperature T ₇ below the glass transition temperature by Fixed to the second shape by The temperature T ₄ by exposure is that above, the second shape memory polybutylene terephthalate laminate film characterized by returning to the first shape from the shape. The shape memory polybutylene terephthalate laminate film according to claim 16, wherein the temperature T _Four Is 75-100 ° C., and the temperature T _Five Is 40 ° C. or less, and the temperature T ₆ Is 45 to 65 ° C., and the temperature T ₇ Is a shape memory polybutylene terephthalate laminate film characterized by being 40 ° C. or lower. The shape memory polybutylene terephthalate laminated film according to claim 16 or 17, wherein the temperature T _Four Is a shape memory polybutylene terephthalate laminate film characterized by being 90-100 ° C. The shape memory polybutylene terephthalate laminated film according to any one of claims 13 to 18 , wherein the first shape is a curl shape, and the second shape is a substantially flat shape or an inverted curl shape. A shape memory polybutylene terephthalate laminate film. The shape memory polybutylene terephthalate laminated film according to any one of claims 13 to 18, wherein the first shape is a tray shape, and the second shape is a flat shape. Butylene terephthalate laminated film. A packaging material comprising the shape memory polybutylene terephthalate laminated film according to any one of claims 13 to 20 . 21. A container lid body comprising the shape memory polybutylene terephthalate laminated film according to any one of claims 13 to 20 .

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