JP7153255B1 - Composite film, laminated film and laminate using the same - Google Patents

Abstract

Composite films, laminated films, and their use that have excellent low-temperature heat-sealability, good sealing performance in conventional bag making and high-speed filling, and excellent processability when laminating a functional layer on the film surface. provide a laminated body. A composite film having at least two layers, a base layer (A) and a heat seal layer (B), wherein the base layer (A) is a propylene random copolymer (a1) of 100 parts by mass, melted at 190 ° C. Made of a resin composition mixed with 1 to 10 parts by mass of a high-density polyethylene (a2) having a flow rate of less than 10 g/10 minutes, the heat seal layer (B) is composed of 100 parts by mass of a propylene random copolymer (b1). part and 1 to 20 parts by mass of high-density polyethylene (b2) having a melt flow rate at 190 ° C. of less than 10 g / 10 minutes, and the resin composition is a differential in JIS K 7121 (1987) A composite film having an extrapolated melting initiation temperature (Tim) measured by scanning calorimetry of 110° C. or lower and a melting point of 120° C. or higher, and a laminate using the same.

Description

TECHNICAL FIELD The present invention relates to composite films, laminated films, and laminates using the same. More specifically, a composite film having good sealability with little breakage on the hot plate during heat sealing and tunneling phenomenon (poor sealability due to floating of the heat-sealed portion), and a function-imparting layer laminated on the composite film. It relates to a laminate.

A laminate obtained by laminating a polyethylene terephthalate (PET) film or a nylon (Ny) film, particularly an oriented PET film or an oriented nylon film (ONy) as a base film, with a polypropylene film as a sealant film, as a laminate for food packaging. is widely known to be used.

In particular, unstretched polypropylene film is excellent as a food packaging material because it can be heat-sealed at a low temperature and has excellent heat resistance and workability. It can be used in a wide range of applications, mainly for packaging, by adding functionalities such as decoration and light shielding properties.

Recently, against the background of the global increase in marine plastic litter, there is a need to promote the recycling of used plastic packaging materials. As a single material (monomaterial) structure, a laminate of biaxially oriented polypropylene/non-oriented polypropylene sealant film is required.

A single-layer film made of a propylene/α-olefin copolymer (see Patent Document 1) and a base layer (A) and a heat-seal layer (B) for the purpose of improving low-temperature sealing properties during bag making and high-speed filling. A film having a two-layer structure and having a lower melting point of the heat seal layer (Patent Document 2) is known.

However, the films of Patent Documents 1 and 2 are not suitable for producing packaging bags by heat-sealing with a hot plate, or when heat-sealing food or the like in a bag product (at the edge of the hot plate). , Insufficient melting of the sealant resin and insufficient adhesive strength at the composite interface, that is, insufficient low-temperature heat sealability and poor sealing performance. In addition, the anti-blocking property was inferior.

Japanese Patent Publication No. 6-68050 JP-A-9-85912

The laminate of biaxially oriented polypropylene/non-oriented polypropylene sealant film has poor heat resistance, and the laminate melts at the high-speed filling temperature after conventional bag making, so the bag making temperature is lowered and the filling speed is also lowered. There is a need. Therefore, it is a big obstacle in developing new applications.

An object of the present invention is to provide excellent low-temperature heat-sealability and anti-blocking properties, good sealability in conventional bag making and high-speed filling, and excellent workability when laminating a function-imparting layer on the film surface. The object of the present invention is to provide a composite film, a laminate film, and a laminate using the same.

In order to solve the above problems, the present invention is as follows.
(1) A composite film having at least two layers, a base layer (A) and a heat seal layer (B), wherein the base layer (A) contains 100 parts by mass of a propylene random copolymer (a1) and 190 parts by mass of A resin composition mixed with 1 to 10 parts by mass of high-density polyethylene (a2) having a melt flow rate at ° C. of less than 10 g/10 minutes, and the resin composition of the heat seal layer (B) is a mixture of propylene and random. A heat seal layer (B) made of a resin composition obtained by mixing 100 parts by mass of a polymer (b1) with 1 to 20 parts by mass of a high-density polyethylene (b2) having a melt flow rate at 190 ° C. of less than 10 g/10 minutes. The resin composition has an extrapolated melting initiation temperature (Tim) of 110° C. or lower and a melting point (Tm) of 120° C. or higher according to JIS K 7121 (1987) by differential scanning calorimetry.
(2) The propylene/random copolymer (a1) of the base layer (A) is an ethylene/propylene random copolymer, a propylene/1-butene random copolymer, and an ethylene/propylene/1-butene ternary. The composite film according to (1), which is one or more selected from the group consisting of copolymers.
(3) The propylene/random copolymer (b1) of the heat seal layer (B) is an ethylene/propylene random copolymer, a propylene/1-butene random copolymer, and an ethylene/propylene/1-butene 3 The composite film according to (1) or (2), which is one or more selected from the group consisting of original copolymers.
(4) The composite film according to any one of (1) to (3), wherein the base layer (A) contains 30% by mass or less of the constituent component of the heat seal layer (B) as a self-recovery component of the composite film. .
(5) A biaxially oriented polypropylene film having a thickness of 20 μm or more is laminated on the composite film using an adhesive by a dry lamination method, and the heat seal layer (B) surfaces of the composite film are overlapped and heated at 120 ° C. The composite film according to any one of (1) to (4), which has a heat-seal strength of 6 N/15 mm or more when heat-sealed by pressing.
(6) A laminated film comprising a base layer (A) of the composite film according to any one of (1) to (5), and a function imparting layer imparting a specific function to the surface of the base layer (A).
(7) The laminated film according to (6), wherein the specific function is at least one selected from the group consisting of gas barrier properties, light shielding properties, glossiness, wettability, easy adhesion, and easy printability.
(8) The laminated film according to (6) or (7), which has an oxygen permeability of 50 cc/(m ² ·day·atm) or less at 23° C. and 0% humidity.
(9) A laminate obtained by laminating the laminated film according to any one of (6) to (8) and another substrate so that the function-imparting layer is on the side of the other substrate.
(10) The laminate according to (9), wherein the other base material is a biaxially stretched polypropylene film using a polypropylene resin with stereoregularity of 90 to 98%.

By adopting the structure of the present invention, it has excellent low-temperature heat-sealing property and blocking resistance, good sealing property at conventional bag making and high-speed filling speed, and processing when laminating a function-imparting layer on the film surface. Excellent in nature. In addition, by laminating a function-imparting layer on the surface of the base layer (A) and further laminating another base material thereon to form a packaging laminate, it is possible to have a high degree of high-speed filling suitability and packaging. During filling, excellent productivity is realized without troubles.

The present invention will be described in more detail below together with preferred embodiments.

The propylene/random copolymer (a1) used for the base layer (A) in the present invention is an ethylene/propylene random copolymer, an ethylene/propylene block copolymer, an ethylene/propylene/1-butene terpolymer or A mixture thereof may be used, and an ethylene/propylene/1-butene terpolymer is preferred from the viewpoint of adhesion to the function-imparting layer and secondary workability.

The melting point of the propylene random copolymer (a1) is 140° C. or higher, preferably in the range of 145 to 155° C., so that the high-speed filling property during bag making is excellent, and the function-imparting layer is laminated. It is preferable because it improves workability and adhesion.

The melt flow rate (hereinafter sometimes abbreviated as MFR) of the propylene random copolymer (a1) is preferably in the range of 2 to 20 g/10 minutes, preferably 5 to 15 g/10 minutes. If the MFR is less than 2 g/10 minutes, the fluidity of the polymer may be insufficient in extrusion, and if it exceeds 20 g/10 minutes, problems may arise in film forming stability in casting.

In the base layer (A), 1 to 10 parts by mass of high-density polyethylene (a2) is mixed with 100 parts by mass of the propylene random copolymer (a1) to increase the rigidity of the film. If the mixing amount of the high-density polyethylene (a2) is less than 1 part by mass, the effect of imparting rigidity is not observed, and if the amount is greater than 10 parts by mass, the effect of imparting rigidity does not change. The density of the high-density polyethylene (a2) is , 0.935 to 0.965 g/cm ³ to improve blocking resistance and slipperiness of the film. If the density is less than 0.935 g/cm ^{3 ,} the effect of the addition may not be observed. It may get worse.

The MFR of the high-density polyethylene (a2) is less than 10 g/10 minutes, more preferably in the range of 1 to 8 g/10 minutes. If the MFR exceeds 10 g/10 minutes, melt fracture may occur and the film forming stability may deteriorate.

The propylene/random copolymer (b1) used in the heat seal layer (B) in the present invention is an ethylene/propylene random copolymer, a propylene/1-butene random copolymer, or an ethylene/propylene/1-butene ternary copolymer. A polymer or a mixture thereof is preferable, and a mixture of an ethylene/propylene random copolymer and a propylene/1-butene random copolymer is particularly preferable because it can achieve both blocking resistance and low-temperature heat sealability.

The propylene random copolymer (b1) may be the same as or different from the propylene random copolymer (a1).

The resin composition of the heat seal layer (B) in the present invention has an extrapolated melting initiation temperature (Tim) of 110° C. or less by differential scanning calorimetry according to JIS K 7121 (1987). If the extrapolated melting start temperature (Tim) exceeds 110°C, the low-temperature sealability is not satisfied, and the extrapolated melting start temperature (Tim) is preferably 95°C or less. Ethylene/propylene random copolymer, propylene/1-butene random copolymer, propylene/1-butene terpolymer, or a mixture thereof has two or more endothermic peaks when dissolved by differential scanning calorimetry. If detected, the extrapolated melting start temperature (Tim) of the heat seal layer (B) is the one with the larger endothermic peak.

The resin composition of the heat seal layer (B) in the present invention preferably has a melting point (Tm) of 120° C. or higher and 145° C. or lower by differential scanning calorimetry according to JIS K 7121 (1987). If the melting point (Tm) is less than 120°C, the anti-blocking property is deteriorated. If the temperature is 145° C. or higher, the low-temperature sealing property is deteriorated. Ethylene/propylene random copolymer, propylene/1-butene random copolymer, propylene/1-butene terpolymer, or a mixture thereof has two or more endothermic peaks when dissolved by differential scanning calorimetry. If detected, the melting point (Tm) of the heat seal layer (B) is defined as the temperature of the peak maximum value of the larger endothermic peak area.

The MFR of the propylene random copolymer (b1) is preferably 3 to 20 g/10 minutes, more preferably 5 to 15 g/10 minutes. If the MFR is less than 3 g/10 min, the melt viscosity is too high, and it may become difficult to stably extrude from the die during film formation. Problems with film stability may occur.

The heat seal layer (B) in the present invention has high blocking resistance by using a resin composition obtained by mixing 100 parts by mass of the propylene random copolymer (b1) with 1 to 20 parts by mass of the high-density polyethylene (b2). Become. If the amount of high-density polyethylene (b2) mixed is less than 1 part by mass, the effect of imparting blocking resistance may not be observed, and if the amount is more than 20 parts by mass, uneven flow at the interface with the base layer (A) may occur. In that case, the stability of the film is deteriorated, the slackness of the film is increased, the secondary workability is deteriorated, and the low-temperature heat sealability is also deteriorated.

The density of the high-density polyethylene (b2) is preferably in the range of 0.935 to 0.965 g/cm ³ to improve blocking resistance and slipperiness of the film. If the density is less than 0.935 g/cm ³ , the effect of addition may not be observed, and if the density exceeds 0.965 g/cm ³ , low-temperature heat sealing may deteriorate.

The MFR of the high-density polyethylene (b2) is less than 10 g/10 min, more preferably in the range of 5-10 g/10 min. If the MFR exceeds 10 g/10 minutes, melt fracture may occur and the film forming stability may deteriorate.

The melting point of the high-density polyethylene (b2) is preferably 140° C. or lower. If the melting point exceeds 140° C., the curling of the film may become large, and troubles may occur during secondary processing such as bag making and provision of a function-imparting layer. In addition, when the composite film of the present invention is laminated with another base material and heat-sealed with a hot plate to produce a packaging bag, or when food is stuffed into a bag product, the sealant resin is insufficiently melted and filled, resulting in poor sealing performance. may occur. Although the lower limit of the melting point is not limited, it is about 100°C. If the thickness is less than this, the slipperiness of the film is deteriorated, and blocking is likely to occur, and the ease of opening the bag may be deteriorated when the content is filled into the bag product, which may cause troubles. The high density polyethylene (b2) may be the same as or different from the high density polyethylene (a2).

The base layer (A) in the present invention as described above is used as a self-collecting component of the composite film according to the present invention (that is, as a component of scraps of the composite film and the edge portion to be collected), and a heat seal layer such as the following It preferably contains 30% by mass or less of the component (B), more preferably 2 to 10% by mass. By enabling the self-recovery component of the composite film to be recovered without significantly changing the composition and ratio of the main component of the base layer (A), the target performance of the composite film according to the present invention is ensured. It becomes possible to keep the production yield of the composite film according to

The method for mixing the resin composition is not particularly limited, and the resin composition can be mixed by a conventionally known method. For example, dry blending or melt blending may be used.

For the composite film, Mitsui Chemicals, Inc. polyether urethane dry laminating adhesive "Takelac (registered trademark)" A969V type 30 parts by mass, Mitsui Chemicals, Inc. dry laminating curing agent "Takelac (registered trademark)" 10 parts by mass of A10 type and 100 parts by mass of ethyl acetate were weighed and stirred for 30 minutes to prepare an adhesive solution for dry lamination having a solid concentration of 19% by mass. Next, the adhesive solution was applied onto the surface of the base layer (A) of the composite film by a bar coating method and dried at 80° C. for 45 seconds to form an adhesive layer with a thickness of 2 μm. Next, a 20 μm biaxially stretched polypropylene film (U-0, manufactured by Mitsui Chemicals, Inc.) is overlaid on the adhesive layer as another base material so that the corona-treated surface faces the adhesive layer. ) manufactured by "Lami Packer (registered trademark)" LPA330, the heat roll was heated to 40°C to bond them together. This laminate film was stored in an oven heated to 40° C. for 2 days to obtain a laminate.

Next, the heat-seal layers (B) of the laminate were superimposed and heat-sealed using a flat plate heat sealer under the conditions of a sealing temperature of 120°C, one side heating, a sealing pressure of 0.1 MPa, and a sealing time of 1 second. The heat seal strength of the sample was measured at a tensile speed of 300 mm/min using "Tensilon" manufactured by Orientec. When the heat seal strength at this time is 6 N/15 mm or more, the sealability at bag making and high speed filling is good, which is preferable. If it is less than 6 N/15 mm, the temperature for sealing the bag must be raised, and the other base material will melt and the appearance of the sealed portion will be significantly deteriorated.

Further, the base layer (A) and the heat seal layer (B) contain an antioxidant, a heat stabilizer, a neutralizer, and an antistatic agent within a range that does not impede the heat sealability and the lamination property of the function-imparting layer. , a hydrochloric acid absorbent, an anti-blocking agent, a lubricant, a crystal nucleating agent, and the like. One type of these additives may be used, or two or more types may be used in combination.

It is preferable to add 300 to 5000 ppm of inorganic particles or organic particles as the anti-blocking agent, because defects such as wrinkles and poor air evacuation are reduced when the composite film of the present invention is wound into a long length. If the content of inorganic particles or organic particles is less than 300 ppm, the effect of imparting anti-blocking properties may not be observed, and if it exceeds 5000 ppm, the heat-sealing force may decrease.

Preferred examples of the inorganic particles include silica, zeolite, and calcium carbonate, and examples of the organic particles include crosslinked polystyrene particles and crosslinked polymethyl methacrylate particles. Their average particle size is preferably in the range from 1 to 5 μm. If the average particle diameter is less than 1 μm, the effect of addition may not be observed, and if it exceeds 5 μm, the heat-sealing force may decrease.

Specific examples of antioxidants include hindered phenols such as 2,6-di-t-butylphenol (BHT), n-octadecyl-3-3',5'-di-t-butyl-4'-hydroxy phenylpropionate (“Irganox” 1076, “Sumilizer” BP-76), tetrakis[methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]methane (“Irganox” 1010, "Sumilizer" BP-101), tris-3,5-di-t-butyl-4-hydroxybenzyl isocyanurate ("Irganox" 3114, Mark AO-20) and the like. In addition, tris-2,4-di-t-butylphenyl phosphite (“Irgafos” 168, Mark 2112), tetrakis 2,4-di-t-butylphenyl-4 as phosphite-based (phosphorus-based) antioxidants -4′-biphenylene-diphosphonite (“Sandstab” P-EPQ), bis 2,4-di-t-butylphenyl pentaerythritol diphosphite (“Ultranox” 626, Mark PEP-24G), distearyl pentaerythritol diphosphite Phyto (Mark PEP-8) and the like. Among them, 6-[3-(3-t-butyl-4-hydroxy-5-methyl)propoxy]-2,4,8,10-tetra- which has both hindered phenol and phosphite functions. t-Butyldibenz[d,f][1,3,2]-dioxaphosphepine (“Sumilizer” GP) and 1′-hydroxy[2,2′-ethylidenebis[4,6-bisacrylate] (1,1-Dimethylpropyl)benzene]]-1-yl (“Sumilizer” GS) is preferred, and in particular, the combined use of both is effective in suppressing oxidative deterioration during film formation, blocking resistance and It is preferable because it contributes to compatibility with low-temperature heat-sealability. The amount of antioxidant to be added may be appropriately set within the range of 100 to 10,000 ppm, depending on the type of antioxidant used.

As the crystal nucleating agent, known crystal nucleating agents such as metal phosphate nucleating agents, sorbitol nucleating agents, and metal carboxylate nucleating agents can be used.

The composite film of the present invention can contain a thermoplastic elastomer, resulting in a lower seal initiation temperature and improved productivity in bag making and high filling speeds. The amount of the thermoplastic elastomer to be added may be appropriately set within the range of 5 to 30 parts by mass depending on the type of thermoplastic elastomer used.

The above thermoplastic elastomer has a hard segment phase and a soft segment phase, so that it has rubber elasticity at 25°C, while it is hard in the general thermoplastic molding temperature range of 100°C to 300°C. It refers to a high molecular weight material that can be molded in the same manner as general thermoplastic resins by exhibiting fluidity in the segment phase. As the thermoplastic elastomer used for the seal layer, for example, a polyester elastomer, a polyolefin elastomer, a polyamide elastomer, a polyurethane elastomer, a styrene elastomer, a polyacrylic elastomer, and the like can be used singly or in combination. Among them, polyolefin elastomers and hydrogenated styrene elastomers are preferably used from the viewpoint of the low-temperature sealability of the resulting film.

Preferred examples of the polyolefin-based elastomer include propylene-based elastomers and ethylene-based elastomers.

The propylene-based elastomer is an elastomer containing structural units derived from propylene, and is preferably exemplified by copolymers containing structural units derived from propylene. In the propylene-based elastomer, the content of propylene-derived structural units is preferably 30 to 90% by mass, more preferably 50 to 90% by mass. In the case of this range, it is easy to obtain a composite film having excellent low-temperature sealability, which is preferable.

Other copolymer components constituting the propylene-based elastomer include, for example, ethylene, 1-butene, 2-methylpropylene, 1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1- Structural units derived from monomers such as pentene and 1-octene can be mentioned. Among them, ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene and the like are preferable, and ethylene and 1-butene are particularly preferable. These are used alone or in combination of two or more. The propylene-based elastomer preferably contains an ethylene-derived structural unit. In the propylene-based elastomer, the content of ethylene-derived structural units is preferably 5 to 20% by mass, more preferably 8 to 15% by mass.

The ethylene-based elastomer is preferably a low-crystalline random copolymer of ethylene and an α-olefin having 3 to 8 carbon atoms, more preferably a low-crystallinity random copolymer of ethylene and an α-olefin having 3 to 4 carbon atoms. It is a heterogeneous random copolymer. As the low-crystalline random copolymer of ethylene and an α-olefin having 3 to 8 carbon atoms, an ethylene/butene random copolymer having excellent low-temperature sealability is preferable, and an ethylene/butene-1 random copolymer is more preferable. be. The content of the α-olefin having 3 to 8 carbon atoms is in the range of 5 to 25% by mass, preferably 10 to 20% by mass, since both blocking resistance and low-temperature sealability can be achieved.

The density of the ethylene-based elastomer is 0.865 to 0.890 g/cm ³ , and the endothermic amount of melting in the temperature rising process is found to be in the range of 5 to 30 J/g by a differential scanning calorimeter (DSC) based on JIS K7122. preferable. If the density is less than 0.865 g/cm ³ , blocking resistance may deteriorate, and if the density exceeds 0.890 g/cm ³ , impact resistance may deteriorate.

The hydrogenated styrene elastomer has a structure consisting of at least one polymer block A mainly composed of a vinyl aromatic compound and at least one polymer block B mainly composed of a hydrogenated conjugated diene compound. Examples thereof include hydrogenated block copolymers composed of ABA, BABA, BABAB and mixtures thereof. The hydrogenated block copolymer preferably contains 10 to 40% by mass of a vinyl aromatic compound.

Examples of the vinyl aromatic compound constituting the polymer block A include styrene and α-methylstyrene, with styrene being particularly preferred. Examples of the conjugated diene compound before hydrogenation of the hydrogenated conjugated diene compound constituting the polymer block B include butadiene, isoprene and 1,3-pentadiene, with butadiene and isoprene being particularly preferred. In the vinyl aromatic compound-conjugated diene compound block copolymer, 80%, preferably 90% or more of the aliphatic double bonds based on the conjugated diene compound are hydrogenated to form the olefinic compound polymer block B. .

Typical hydrogenated styrene elastomers include styrene/ethylene/butylene/styrene block copolymer (hereinafter abbreviated as SEBS) and hydrogenated styrene/isoprene/styrene block copolymer (hereinafter abbreviated as SIS). and the like, and SEBS is particularly preferred. SEBS having a low styrene content and a high ethylene and butylene content have excellent compatibility with the sea component of the ethylene-propylene copolymer of the sealing layer. Specifically, "DYNARON" 8601P manufactured by JSR Corporation, "TUFTEC" H1062 manufactured by Asahi Kasei Corporation, G1660 manufactured by Clayton Polymer Japan Co., Ltd., etc. can be suitably used. is preferably in the range of 12/88 to 67/33.

Also, the heat seal layer (B) may contain 10 to 30 parts by mass of an ethylene/α-olefin copolymer. The α-olefin consists of butene, hexene, octene, or mixtures thereof, preferably linear low density polyethylene. From the viewpoint of seal strength, the linear low-density polyethylene is preferably produced using a metallocene catalyst.

The linear low-density polyethylene preferably has a density of 0.900 to 0.935/cm ³ , more preferably 0.915 to 0.930/cm ³ . If the density of the linear low-density polyethylene is less than 0.900 g/cm ³ , the blocking resistance may deteriorate, and if it exceeds 0.935 g/cm ³ , the dispersibility may deteriorate.

The composite film of the present invention may have a two-layer laminate structure of the base layer (A) and the heat seal layer (B) as described above, or may have three or more layers with another intermediate layer (C) interposed between the two layers. A laminated structure is also possible. As the intermediate layer (C), the resin composition of the base layer (A) or a material such as homopolypropylene that improves the strength and rigidity of the film is preferable. In terms of quality stabilization and cost reduction, flakes obtained by pulverizing slit scraps generated in the process of producing the composite film of the present invention or recycled pellets can be mixed and used.

The method of laminating the composite film having the base layer (A), the heat seal layer (B) and the intermediate layer (C) in the present invention is not particularly limited. Lamination methods such as pipe composite such as block method and co-extrusion multi-layer die method are generally used.

Although the thickness of the composite film of the present invention is not particularly limited, it is usually about 15 μm to 80 μm, and particularly preferably 20 μm to 40 μm from the viewpoint of handling. The thickness ratio of the heat seal layer (B) is preferably 10 to 50% of the total thickness, more preferably 15 to 40%. If the thickness ratio of the heat-seal layer (B) is less than 10%, the heat-sealing force may decrease, resulting in poor sealing performance. On the other hand, if it exceeds 50%, the heat resistance is lowered, and the high-speed filling property, the lamination of the function-imparting layer, and the lamination with other substrates may be deteriorated.

The composite film of the present invention can be a laminated film in which a function-imparting layer that imparts specific functionality is provided on the surface of the base layer (A).

The function-imparting layer in the present invention means a layer that imparts specific functionality to the composite film. The specific functionality is at least one functionality selected from gas barrier properties, light shielding properties, glossiness, easy adhesion to other substrates, and easy printability. A particular functionality may be only one functionality, or there may be several functionality.

The gas barrier property in the present invention refers to the barrier property against oxygen gas, water vapor, nitrogen gas and carbon dioxide gas, preferably the gas barrier property against oxygen gas and water vapor. The oxygen gas barrier property can be measured by the method of JIS K 7126, and the oxygen gas barrier property in the present invention means the oxygen permeability at a temperature of 23° C. and a relative humidity of 0%.

The water vapor barrier property can be measured by the method of JIS K 7129B, and refers to the water vapor transmission rate at a temperature of 40°C and a relative humidity of 90%. The oxygen permeability is preferably 50 cc/(m ² ·24 hr·atm) or less, more preferably 30 cc/(m ² ·24 hr·atm) or less.

The term "light-shielding property" as used in the present invention refers to functionality in which the total light transmittance measured by the method of JIS K 7361 is 5% or less. More preferably, the total light transmittance is 3% or less.

The term "glossiness" as used in the present invention means the glossiness measured at 60° for both incident light and reflected light by the method of JIS Z 8741. The glossiness of the layer imparting functions after vapor deposition of aluminum is preferably 300% or more, more preferably 400% or more.

The ease of adhesion to other substrates in the present invention refers to ease of adhesion to other substrates, which will be described later. The ease of adhesion refers to the ease of adhesion of the composite film of the present invention to the base layer (A). The adhesive used when bonding to other substrates is easy to adhere to the base layer (A) of the composite film of the present invention, and the base layer of the composite film of the present invention of the extruded resin during extrusion lamination processing ( A), the ease of adhesion of the extruded resin to the base layer (A) of the composite film of the present invention during extrusion coating processing, and the sputtering and vapor deposition components during sputtering and vacuum deposition are the components of the present invention. ease of adhesion of the composite film to the base layer (A) of the composite film of the present invention;

A method for imparting easy adhesion is not particularly limited, but includes a method of treating the surface of the base layer (A) of the composite film. Examples of surface treatment methods include corona treatment, flame treatment, plasma treatment, ozone treatment, ion treatment, sputtering treatment, sandblasting treatment, surface modification treatment with resin such as anchor coating, and the like.

The base layer (A ) to roughen the surface of the base layer (A) to physically form surface irregularities having an anchoring effect on the surface of the base layer (A). can be

The method of treating the surface of the base layer (A) may be carried out in-line during the formation of the composite film of the present invention, or may be carried out off-line after the formation of the composite film of the present invention. Further, only the surface treatment may be performed, or when forming the function-imparting layer, the function-imparting layer may be formed continuously after the surface treatment of the base layer (A). After forming the function-imparting layer, the surface thereof may be treated.

The easy printability in the present invention means ease of printing on the base layer (A) of the composite film of the present invention. Printing is performed in order to display character information, pictures, and the like that are necessary for packages such as packaging bags. Ingredients for printing include, for example, various pigments in conventionally used ink binder resins such as urethane, acrylic, nitrocellulose, and rubber, and additives such as plasticizers, desiccants, and stabilizers. etc., and the ease of printing means that the components of printing are likely to adhere when printing, and there is little dropout such as missing dots of ink.

A method for imparting easy printability is not particularly limited, but includes a method of treating the surface of the base layer (A) of the composite film.

Examples of methods for surface treatment include corona treatment, flame treatment, plasma treatment, ozone treatment, ion treatment, and surface modification treatment with a resin such as anchor coating. A method of forming on the surface of the base layer (A) a functional group or the like highly reactive to the printing ink, a method of using an anchor coat resin to which the printing ink easily adheres, and a wettability improving agent for improving wettability. and the like are added to the anchor coat.

The timing of treating the surface of the base layer (A) may be performed before printing, and may be performed in-line during the formation of the composite film of the present invention, or may be performed off-line after the formation of the composite film. Also good.

If the functions of the gas barrier property, light shielding property, glossiness, easy adhesion to other substrates, and easy printability in the present invention can be imparted, the function-imparting layer can be an inorganic layer, an organic layer, or an inorganic-organic mixture layer. Either one is fine. Further, these may be one layer, or may be a layer in which a plurality of layers are laminated. When a plurality of layers are laminated, the order of lamination is not particularly limited as long as the intended function is satisfied. Examples of the inorganic layer include a metal layer and an inorganic oxide layer.

Although the metal layer is not particularly limited, aluminum is preferable from the viewpoint of gas barrier properties, light shielding properties, glossiness, and cost. The thickness of the metal layer is preferably 20 nm or more and less than 100 nm, more preferably 22 nm or more and less than 80 nm. An optical density of 1.5 or more and a metallic luster of 600% or more are practical. If the thickness of the metal layer is less than 20 nm, the optical density is 1.5 or less and the glossiness is 600% or less. . When the thickness of the metal layer is 100 nm or more, there is no problem with the light-shielding property and metallic luster, but the thicker the metal layer, the vapor-deposited layer is more susceptible to heat loss, and the gas barrier performance and lamination strength may decrease.

An inorganic oxide layer is preferable if the contents can be visually recognized and gas barrier properties are imparted. Examples of inorganic oxides include, but are not limited to, aluminum oxide, silicon oxide, magnesium oxide, zinc oxide, silicon dioxide, and zinc oxide or zinc sulfide containing aluminum oxide, zinc oxide-silicon dioxide-aluminum oxide. A layer consisting of a coexisting phase of zinc sulfide and silicon dioxide, a layer consisting of a coexisting phase of zinc sulfide and silicon dioxide, diamond-like carbon, or a mixture thereof. , magnesium oxide are preferred, and aluminum oxide and silicon oxide are more preferred.

The method of forming these metal layers and inorganic oxide layers is not particularly limited, but the metal is directly heated to evaporate, and the metal layer is formed on the surface of the base layer (A) of the composite film of the present invention. a reactive vapor deposition method in which an inorganic oxide layer is formed by reacting a heated and evaporated metal with oxygen gas, an ion plating method in an oxygen gas atmosphere, a sputtering method using a target material as a target, A known method such as a reactive sputtering method in which sputtered particles are reacted with oxygen gas during sputtering, a chemical vapor deposition method, or the like can be used.

Moreover, before the metal layer and the inorganic oxide layer are formed, the surface of the base layer (A) of the composite film of the present invention may be subjected to functional imparting treatment.

The inorganic oxide layer preferably has a thickness of 10 nm or more and less than 30 nm. If the film thickness is less than 10 nm, the desired lamination strength may not be achieved, or the gas barrier performance may be insufficient. When the film thickness is 30 nm or more, the amount of reaction heat increases during the oxidation reaction of aluminum, so that the base layer (A) may be deformed by the reaction heat and the appearance may become unusable. The thickness of the aluminum oxide layer and the metal aluminum layer can be calculated from the composition distribution (so-called depth profile) of aluminum and oxygen at the sputtering depth obtained by X-ray photoelectron spectroscopy or Auger electron spectroscopy.

Organic resin layers include vinylidene chloride resins, polyvinyl alcohol resins, polyurethane resins, polyepoxy resins, polyester resins, polyacrylic resins, ethylene vinyl alcohol copolymers, and the like. When imparting oxygen barrier properties, it is preferable to coat with an ethylene-vinyl alcohol copolymer.

Examples of the inorganic-organic mixture layer include a layer in which an inorganic substance is mixed with the organic resin, a layer in which an organic resin and an inorganic component are combined, and the like. The inorganic material to be mixed may be either a tabular inorganic material or a particulate inorganic material. When imparting a light-shielding property, titanium oxide or the like is preferable as the particulate inorganic material for the purpose of reflecting and blocking light.

In addition, materials such as an oxygen absorber may be contained in these organic substances and organic inorganic substances.

The thickness of the inorganic-organic mixture layer is preferably 0.5 to 1000 μm, more preferably 1 to 500 μm, still more preferably 1 to 100 μm, and particularly preferably 1 to 50 μm.

The method for forming these organic layer and inorganic-organic mixture layer is not particularly limited, and the base layer (A) of the composite film of the present invention, the functionality imparting layer on the base layer (A), the base layer (A ) on the functionally treated surface. For example, a roll coating method, a dip coating method, a bar coating method, a die coating method, a knife edge coating method, a gravure coating method, a kiss coating method, a spin coating method, a spray method, or a combination thereof can be used. can.

Next, on the base layer (A) of the composite film of the present invention, or on the above functionality-imparting layer laminated on the base layer (A), another substrate may be laminated to further improve the functionality. can. The laminated structure of these laminates meets the required properties of packaging bags (for example, gas barrier properties to meet the shelf life of the packaged food, size and impact resistance that can accommodate the mass of the contents, visibility of the contents, etc.). selected as appropriate.

The above-mentioned other substrates are not particularly limited as long as properties such as mechanical strength, heat resistance, and light resistance are taken into account depending on the application, but typical examples include polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, and polybutylene 2,6. -Polyesters such as naphthalate, polyvinyl alcohol, ethylene-vinyl acetate copolymer saponified products, polyolefins such as polystyrene, polycarbonate, polyethylene, polypropylene, polyamides such as 6 nylon, 12 nylon, aromatic polyamides, polyimides and other homopolymers or Films and sheets made of copolymers can be mentioned. From the viewpoint of strength retention and puncture resistance against contents, plastic films such as polyamide films, paper substrates, film laminates obtained by laminating these plastic films with adhesives, etc., polymer films and paper substrates are bonded. Examples include a paper laminate obtained by laminating with an agent or the like. Above all, there is a strong demand for recycling plastic packaging materials after use against the backdrop of an increase in marine plastic litter worldwide. A laminate of biaxially oriented polypropylene and the composite film of the present invention as a single-material (mono-material) system configuration enables collection of the same material, which is preferable from the viewpoint of reducing environmental load.

The above biaxially oriented polypropylene is preferably made of a polypropylene resin having a stereoregularity in the range of 90 to 98%, which indicates the proportion in which the methyl groups of propylene are regularly arranged in one direction. If the stereoregularity is less than 90%, the rigidity of the film decreases, and when the film is laminated with the composite film, the film may stretch due to tension and wrinkles easily, resulting in high-speed filling of bag products. , the performance of the functionality-imparting layer may deteriorate. If the stereoregularity exceeds 98%, the crystallinity may increase, the surface roughness of the film may increase, and the adhesion to the function-imparting layer may decrease.

Methods for laminating the composite film of the present invention with other substrates include dry lamination method, wet lamination method, non-solvent lamination method that does not use a solvent, and extrusion. A known method such as an extrusion sand lamination method using a resin can be used.

A laminate obtained by laminating the composite film of the present invention with the other base material described above can be suitably used as a packaging bag or a packaging container. Examples of packaging bags and packaging containers include gusset bags, standing pouches, brick types, flat types, etc., and various foods, drinks, adhesives, chemicals such as adhesives, cosmetics, miscellaneous goods such as pharmaceuticals. It is possible to fill and package various articles such as.

An example of the method for producing the composite film of the present invention will be described. Using two extruders, from one extruder, 100 parts by mass of a propylene random copolymer (a1) having an MFR of 3 to 12 g / 10 minutes as a resin for the base layer (A), high density polyethylene (a2 ) A resin composition mixed with 1 to 10 parts by mass is melted at a temperature of 220 to 270°C. From another extruder, a resin composition obtained by mixing 100 parts by mass of a propylene random copolymer (b1) and 1 to 20 parts by mass of a high-density polyethylene (b2) was extruded as a heat seal layer (B) at a temperature of It melts at 220-270°C. The base layer (A) and the heat seal layer (B) are laminated using a pipe composite or co-extrusion multilayer die, extruded into a film form from a spinneret, cast with cooling rolls at 30 to 80° C., cooled and solidified to form a composite film. At this time, the ratio of the gap between the lips of the spinneret to the thickness of the cooled and solidified composite film (lip gap/film thickness=draft ratio) is preferably 20-50. By setting this draft ratio, the film is fused and oriented in the longitudinal direction, and the cast film is heat-treated at 40 to 80 ° C. for 0.01 to 1 second with a heated mirror surface roll. can be improved.

Next, as an example of a method of imparting functionality to the surface of the base layer (A) of this composite film, the It is subjected to corona discharge treatment at 20 to 60 W·min/m ² and wound up to obtain the composite film of the present invention.

In addition, as an example of a function-imparting layer on the composite film, it is set in a vacuum deposition apparatus, and aluminum is deposited on the surface of the base layer (A) of the film at a degree of vacuum of 1.3 × 10 ^-2 Pa or more to a thickness of 30 nm. to obtain a metal-deposited laminated film.

The present invention will be described using examples and comparative examples.

Examples 1-12, Comparative Examples 1-16
The following polyolefin resins were used in Examples 1 to 12 and Comparative Examples 1 to 16 of the composite films of the present invention.
(1) Ethylene/propylene random copolymer: melting point 141°C, extrapolated melting initiation temperature 135°C, MFR 7.0 g/10 min, ethylene content 4 mol% (abbreviated as r-EPC).
(2) Ethylene/propylene/1-butene terpolymer: melting point 140°C, extrapolated melting start temperature 134°C, MFR 7.0 g/10 min, ethylene content 2 mol%, butene content 5 mol% (this is abbreviated as r-EPBC).
(3) Propylene/1-butene random copolymer: melting point 125°C, extrapolated melting initiation temperature 115°C, MFR 7.0 g/10 min, butene content 17 mol% (this is abbreviated as r-PBC (1) ).
(4) Propylene/1-butene random copolymer: melting point 125°C, extrapolated melting initiation temperature 90°C, MFR 7.0 g/10 min, butene content 19 mol% (this is abbreviated as r-PBC (2) ).
(5) Propylene/1-butene random copolymer: melting point 125°C, extrapolated melting initiation temperature 100°C, MFR 7.0 g/10 min, butene content 18 mol% (this is abbreviated as r-PBC (3) ).
(6) Propylene/1-butene random copolymer: melting point 110°C, extrapolated melting start temperature 90°C, MFR 7.0 g/10 min, butene content 25 mol% (this is abbreviated as r-PBC (4) ).
(7) High-density polyethylene: NOVATEC HD "HF562" MFR 7.5 g/10 minutes, melting point 134°C, manufactured by Nippon Polyethylene Co., Ltd. (this is abbreviated as HDPE (1)).
(8) High-density polyethylene: Novatec HD "HJ580N" MFR 12.0 g/10 minutes, melting point 134° C. manufactured by Nippon Polyethylene Co., Ltd. (this is abbreviated as HDPE (2)).

The measured values of each evaluation item in the detailed description of the present invention and examples were measured by the following methods.

Tables 1 and 2 show the characteristics of each sample in each example and comparative example.

(1) Melt flow rate (MFR)
According to JIS K-7210-1999, propylene/random copolymer, propylene elastomer and homopropylene are heated at 230°C, high density polyethylene, ethylene/α-olefin copolymer and ethylene elastomer at 190°C. Each was measured with a load of 21.18N.

(2) Density Measured by a density gradient tube measurement method based on JIS K-7112-1999.

(3) Melting point (Tm)
Using a differential scanning calorimeter DSC (DSC-60A) manufactured by Shimadzu Corporation, a 5 mg sample was heated to 250 ° C. at a rate of 10 ° C./min in a nitrogen atmosphere, and the endothermic peak accompanying melting was taken as the melting point (Tm).

(4) Melting point (Tm) of heat seal layer (B) of composite film
A sample obtained by scraping off the surface of the heat seal layer (B) of the composite film with a diamond cutter is obtained under the same conditions as (3), and if two or more endothermic peaks are detected, the melting point at that time is the larger endothermic peak. is the melting point (Tm) of the heat seal layer (B).

(5) Extrapolated melting start temperature (Tim)
Using a differential scanning calorimeter DSC (DSC-60A) manufactured by Shimadzu Corporation, 5 mg of a sample was heated to 250 ° C. at a rate of 10 ° C./min under a nitrogen atmosphere and held for 5 minutes. When cooling to 10 ° C. at a cooling rate of ° C./min and heating again at a rate of 10 ° C./min, a straight line extending the baseline on the low temperature side to the high temperature side and the low temperature side of the melting peak The temperature at the intersection of the tangent lines drawn on the curve at the point of maximum slope.

(6) Extrapolated melting initiation temperature (Tim) of the heat seal layer (B) of the composite film
A sample obtained by scraping off the surface of the heat seal layer (B) of the composite film with a diamond cutter is obtained under the same conditions as in (5). At that time, the extrapolated melting start temperature (Tim) of the heat seal layer (B) is the one with the larger endothermic peak.

(7) Film-forming stability In the film-forming process of the composite film, the following evaluations were made by observing the adhesion of the film to the process roll, the appearance of the film such as wrinkles, and the like.
◯ (Good): Good film-forming properties with no sticking to the process roll in the film-forming process, no wrinkles or stains on the film, and a good appearance with little curl.
x (improper): The film-forming property is unstable due to adhesion to the process roll in the film-forming process, the film has wrinkles and stains due to roll adhesion, and the curl is large and the appearance is poor.

(8) Slack evaluation (curl)
After the composite film is wound into a roll, it is slit to a specified width to obtain a product, and the film is pulled out 2m from the product and checked by pulling it to a finger tension (3 to 4kg with a spring scale). If slack is found, measure its width with a tape measure. If the slack width was less than 100 mm, it was judged as acceptable.

(9) Film thickness Using a dial gauge thickness gauge (JIS B-7509: 1974, stylus 5 mmφ flat type), measure 10 points at intervals of 10 cm in the longitudinal direction and width direction of the film, the average value and

(10) Thickness of each layer A cross-section of the film is cut out with a microtome, and a digital microscope VHX-100 type (manufactured by Keyence Corporation) is used to observe the cross-section at a magnification of 1000 times. The thickness of each layer was obtained by measuring the distance in the thickness direction of each layer and calculating back from the magnification. In determining the thickness of each layer, 5 cross-sectional photographs at 5 locations arbitrarily selected from mutually different measurement fields were used, and the average value thereof was calculated.

(11) Heat seal strength Mitsui Chemicals, Inc. polyether urethane dry laminating adhesive “Takelac (registered trademark)” A969V type 30 parts by mass, Mitsui Chemicals, Inc. dry laminating curing agent “Takelac (registered trademark)” ) "A10 type 10 parts by mass and 100 parts by mass of ethyl acetate were weighed and stirred for 30 minutes to prepare a dry laminate adhesive solution having a solid content concentration of 19% by mass. Next, the adhesive solution was applied onto the surface of the base layer (A) of the composite film by a bar coating method and dried at 80° C. for 45 seconds to form an adhesive layer with a thickness of 2 μm. Next, a 20 μm biaxially stretched polypropylene film (U-0, manufactured by Mitsui Chemicals, Inc.) is overlaid on the adhesive layer as another base material so that the corona-treated surface faces the adhesive layer. ) manufactured by "Lami Packer (registered trademark)" LPA330, the heat roll was heated to 40°C to bond them together. This laminate film was stored in an oven heated to 40° C. for 2 days to obtain a laminate.

Next, the heat-seal layers (B) of the laminate were superimposed and heat-sealed using a flat plate heat sealer under the conditions of a sealing temperature of 120°C, one side heating, a sealing pressure of 0.1 MPa, and a sealing time of 1 second. The heat seal strength of the sample was measured at a tensile speed of 300 mm/min using "Tensilon" manufactured by Orientec. A sample with a heat seal strength of 6 N/15 mm or more at this time was considered to have good low-temperature heat sealability.

(12) Blocking resistance Prepare a film sample with a width of 30 mm and a length of 100 mm, overlap the sealing layers in an area of 30 mm × 40 mm, apply a load of 500 g / 12 cm ² , and place in an oven at 40 ° C. for 24 hours. After the heat treatment, the film was allowed to stand in an atmosphere of 23° C. and 65% RH for 30 minutes or more, and then the shear peel strength was measured at a tensile speed of 300 mm/min using Tensilon manufactured by Orientec. In this measurement method, if the shear peel strength is less ^{than 10} N/12 cm ² , the blocking resistance is “○ (good)”. ² or more was set as "x (impossible)."

(13) Oxygen permeability (gas barrier performance)
As a function-imparting layer on the base layer (A) of the composite film, metal vapor deposition, metal oxide vapor deposition, and an organic layer were laminated as the gas barrier performance of the film under conditions of a temperature of 23 ° C. and a humidity of 0% RH. ) company's oxygen transmission rate measuring device (OXTRAN 2/20), the oxygen transmission rate was measured based on the B method (isobaric method) described in JIS K7126 (2000 edition). Samples were collected from three locations in the width direction of the film, ie, both ends and the central portion, and the average value of the three measured values was used as the value of the oxygen permeability in each example and comparative example. An oxygen permeability value of 50 cc/(m ² ·24 hr·atm) or less was regarded as good gas barrier performance.

(14) Total light transmittance (light shielding property)
The total light transmittance was measured using a haze meter (NDH7000 manufactured by Nippon Denshoku Industries Co., Ltd.). A total light transmittance of 5% or less was defined as a good light shielding property.

(15) Surface glossiness The glossiness is measured using a variable angle gloss meter type: UGV-5D manufactured by Suga Test Instruments Co., Ltd., according to JIS Z8741 (1983), incident angle 60 ° / reflection angle with respect to the metal deposition surface. The measurement was made at 60°, and the average value of 3 points in the width direction of the film was obtained. 600% or more was set as the pass.

(16) Adhesion strength (easy adhesion)
Mitsui Chemicals, Inc. polyether urethane dry laminating adhesive “Takelac (registered trademark)” A969V type 30 parts by mass, Mitsui Chemicals, Inc. dry laminating curing agent “Takelac (registered trademark)” A10 type 10 mass and 100 parts by mass of ethyl acetate were weighed out and stirred for 30 minutes to prepare an adhesive solution for dry lamination having a solid content concentration of 19% by mass.

Next, the adhesive solution was applied to the surface of the function imparting layer of the composite film by a bar coating method and dried at 80° C. for 45 seconds to form an adhesive layer having a thickness of 2 μm.

Next, a 25 μm biaxially oriented polypropylene film (“Torayfan (registered trademark)” YT42 manufactured by Toray Industries, Inc.) is overlaid on the adhesive layer as another base material so that the corona-treated surface faces the adhesive layer. , Fuji Tech Co., Ltd., "Lamipacker (registered trademark)" LPA330, and the heat rolls were heated to 40°C for lamination. This laminate film was stored in an oven heated to 40° C. for 2 days to obtain a laminate. Next, the laminate was cut to a width of 15 mm and a length of 150 mm to prepare a cut sample, and a composite film and biaxially stretched using a tensile tester (RTG-1210 type) manufactured by A&D Co., Ltd. The polypropylene films were peeled at a tensile speed of 300 mm/min by the T-peel method using the interface between the polypropylene films, and the strength was measured. The obtained value was defined as adhesion strength (N/15 mm). An adhesive strength of 1 N/15 mm or more was considered good.

(17) Easy printability Ink (Lamic SR SCR White (M) manufactured by Dainichiseika Kogyo Co., Ltd.) and its dilution solvent (Lamic SR Hardener manufactured by Dainichiseika Kogyo Co., Ltd.) were applied to the surface of the function-imparting layer. An ink prepared at a ratio of 1:1 was applied so as to have a thickness of about 1.0 μm and dried in a hot air oven at 100° C. for 30 seconds. After that, Nichiban Co., Ltd. manufactured "CELLOTAPE (registered trademark)" No. 405 (width 15 mm) was affixed to the printed surface with a rubber roller, peeled off, the state of ink peeling was observed, and the ease of printing was evaluated on a scale of 5 for ink adhesion. 5-grade evaluation “Easy printability (bad)” Grade 1: 90% or more of ink peeling, Grade 2: 50% or more and less than 90% of ink peeling, Grade 3: 10% or more and less than 50% of ink peeling, Grade 4: Ink peeling 1 % or more and less than 10%, grade 5: less than 1% of ink peeling "easily printable (good)".

(18) Film thickness of function-imparting layer Observation with a transmission electron microscope is performed by sampling a film to be observed by a microsampling method, and then using a focused ion beam processing device (FB-2000 manufactured by Hitachi, Ltd.). thin film. After that, carbon and tungsten protective films were formed for protection. This sample was observed with a field emission transmission electron microscope (HF-2200 manufactured by Hitachi, Ltd., hereinafter referred to as TEM).

Example 1
As the base layer (A) of the composite film, 95 parts by mass of the ethylene-propylene random copolymer (r-EPC) as the propylene-random copolymer (a1) and HDPE (1) as the high-density polyethylene (a2). 5 parts by mass, 0.125 parts by mass of an antioxidant (“Irganox” 1010 manufactured by Ciba-Geigy), and 0.3 parts by mass of silica fine particles having an average particle diameter of 3 μm as an anti-blocking agent. 97 parts by mass of the propylene/1-butene random copolymer (r-PBC (2)) and high-density polyethylene (b2) as the heat seal layer (B). 3 parts by mass of HDPE (1) as a resin composition, 0.125 parts by mass of an antioxidant ("Irganox" 1010 manufactured by Ciba-Geigy), and 0.2 parts by mass of silica fine particles having an average particle diameter of 3 μm as an anti-blocking agent. is supplied to another extruder heated to 240 ° C. and melted, laminated and extruded in a multi-manifold die for two-layer lamination heated to 240 ° C., with a draft ratio of 25, 50 ° C. The casting was cooled and solidified with a cooling roll.
Subsequently, the surface of the base layer (A) was subjected to corona discharge treatment at 26 W·min/m ² and wound up. of the coextruded two-layer composite film was obtained. The heat seal layer (B) of the obtained composite film had an extrapolated melting start temperature of 90°C and a melting point of 125°C. In addition, the resulting composite film had good film-forming properties, had no film slack, and was excellent in blocking resistance and low-temperature heat-sealing properties.

Example 2
As the base layer (A) of the composite film, 95 parts by mass of an ethylene/propylene/1-butene terpolymer (r-EPBC) as a propylene/random copolymer (a1) and HDPE as a high-density polyethylene (a2) A coextruded two-layer composite film was obtained in the same manner as in Example 1, except that a resin composition containing 5 parts by mass of (1) was used. The heat seal layer (B) of the obtained composite film had an extrapolated melting start temperature of 90°C and a melting point of 125°C. In addition, the resulting composite film had good film-forming properties, had no film slack, and was excellent in blocking resistance and low-temperature heat-sealing properties.

Example 3
As the sealing layer (B) of the composite film, 42 parts by mass of ethylene/propylene random copolymer (r-EPC) as propylene/random copolymer (b1), propylene/1-butene random copolymer (r-PBC ( 2)) 55 parts by mass, 3 parts by mass of HDPE (1) as high-density polyethylene (b2), and 0.3 parts by mass of silica fine particles having an average particle diameter of 3 µm as an anti-blocking agent. A coextruded two-layer composite film was obtained in the same manner as in Example 2, except for the above. The heat seal layer (B) of the obtained composite film had an extrapolated melting start temperature of 110°C and a melting point of 130°C. In addition, the resulting composite film had good film-forming properties, had no film slack, and was excellent in blocking resistance and low-temperature heat-sealing properties.

Example 4
As the sealing layer (B) of the composite film, 97 parts by mass of a propylene/1-butene random copolymer (r-PBC (3)) as a propylene/random copolymer (b1) and HDPE as a high-density polyethylene (b2) A coextruded two-layer composite film was obtained in the same manner as in Example 2, except that (1) was changed to 3 parts by mass. The heat seal layer (B) of the obtained composite film had an extrapolated melting start temperature of 100°C and a melting point of 125°C. In addition, the resulting composite film had good film-forming properties, had no film slack, and was excellent in blocking resistance and low-temperature heat-sealing properties.

Comparative example 1
As the sealing layer (B) of the composite film, 97 parts by mass of the propylene random copolymer (r-EPC) as the propylene random copolymer (b1), and 3 HDPE (1) as the high density polyethylene (b2) A coextruded two-layer composite film was obtained in the same manner as in Example 2 except that a resin composition containing 0.3 parts by mass of silica fine particles having an average particle diameter of 3 μm as an antiblocking agent was used. The heat seal layer (B) of the obtained composite film had an extrapolated melting initiation temperature of 135°C and a melting point of 140°C. Since the extrapolated melting start temperature of the heat-seal layer (B) was 135° C., the low-temperature heat-sealability was poor.

Comparative example 2
As the seal layer (B) of the composite film, 97 parts by mass of the propylene/1-butene random copolymer (r-PBC(1)) as the propylene/random copolymer (b1), and high-density polyethylene (b2), A coextruded two-layer composite film was prepared in the same manner as in Example 2, except that a resin composition containing 3 parts by mass of HDPE (1) and 0.3 parts by mass of silica fine particles having an average particle size of 3 μm as an antiblocking agent was used. got The heat seal layer (B) of the obtained composite film had an extrapolated melting initiation temperature of 115°C and a melting point of 125°C. Since the extrapolated melting start temperature of the heat-seal layer (B) was 115° C., the low-temperature heat-sealability was poor.

Comparative example 3
As the sealing layer (B) of the composite film, 57 parts by mass of the above ethylene/propylene random copolymer (r-EPC) as the propylene/random copolymer (b1), propylene/1-butene random copolymer (r-PBC (2)) 40 parts by mass, 3 parts by mass of HDPE (1) as high-density polyethylene (b2), and 0.3 parts by mass of silica fine particles having an average particle diameter of 3 µm as an anti-blocking agent. A coextruded two-layer composite film was obtained in the same manner as in Example 1, except for the above. The heat seal layer (B) of the obtained composite film had an extrapolated melting initiation temperature of 117°C and a melting point of 135°C. Since the extrapolated melting start temperature of the seal layer (B) was 117° C., the low-temperature heat-sealability was poor.

Comparative example 4
Coextrusion was carried out in the same manner as in Example 1, except that a resin composition containing 100 parts by mass of an ethylene/propylene/1-butene terpolymer (r-EPBC) was used as the base layer (A) of the composite film. A two-layer composite film was obtained. The obtained composite film was inferior in blocking resistance because the high-density polyethylene (a2) was not mixed with the base layer (A).

Comparative example 5
A coextruded two-layer composite film was obtained in the same manner as in Example 2, except that the high-density polyethylene (a2) in the base layer (A) of the composite film was changed to HDPE (2). In the obtained composite film, since the MFR of the high-density polyethylene (a2) of the base layer (A) is 10.0 g/min or more, melt fracture occurs, the film formation stability is poor, and the film sag It was big.

Comparative example 6
A coextruded two-layer composite film was obtained in the same manner as in Example 2, except that the high density polyethylene (b2) in the heat seal layer (B) of the composite film was changed to HDPE (2). In the obtained composite film, since the MFR of the high-density polyethylene (b2) of the heat seal layer (B) is 10.0 g/min or more, melt fracture occurs, the film formation stability is poor, and sagging of the film occurs. was also big.

Comparative example 7
A resin containing 88 parts by mass of propylene/1-butene random copolymer (r-PBC (2)) as the heat seal layer (B) of the composite film and 22 parts by mass of HDPE (1) as the high-density polyethylene (b2). A coextruded two-layer composite film was obtained in the same manner as in Example 2, except that the composition was used. In the obtained composite film, since the mixed amount of the high-density polyethylene (b2) in the heat seal layer (B) was large, disturbance occurred at the lamination interface with the base layer (A), resulting in inferior film formation stability.

Comparative example 8
As the sealing layer (B) of the composite film, 97 parts by mass of the propylene random copolymer (r-PBC (4)) as the propylene random copolymer (b1), HDPE (1) as the high density polyethylene (b1) ) and 0.3 parts by mass of silica fine particles having an average particle diameter of 3 μm as an anti-blocking agent were used. . The heat seal layer (B) of the obtained composite film had an extrapolated melting initiation temperature of 90°C and a melting point of 110°C. Since the melting point of the heat seal layer (B) was as low as 110°C, the blocking resistance was poor.

Example 5
Using the composite film described in Example 2, aluminum was evaporated at a degree of vacuum of 1.3 × 10 ^-2 Pa with an ordinary roll-to-roll type vapor deposition machine to form the base layer of the composite film. An aluminum layer of 40 nm was formed on the surface (A) to obtain a laminated film. This laminated film has an oxygen transmission rate of 15 cc/(m ² · 24 hr · atm) at 23 ° C. and a humidity of 0%, a total light transmission rate of 1.3%, and a glossiness of 600%. The glossiness was good. In addition, the adhesiveness of the aluminum vapor deposition layer, ink printability, and low-temperature sealability were excellent.

Example 6
Using the composite film described in Example 4, aluminum was evaporated at a degree of vacuum of 1.3 × 10 ^-2 Pa with an ordinary roll-to-roll type vapor deposition machine to form the base layer of the composite film. An aluminum layer of 40 nm was formed on the surface (A) to obtain a laminated film. This laminated film has an oxygen transmission rate of 15 cc/(m ² · 24 hr · atm) at 23 ° C. and a humidity of 0%, a total light transmission rate of 1.3%, and a glossiness of 600%. The glossiness was good. In addition, the adhesiveness of the aluminum vapor deposition layer, ink printability, and low-temperature sealability were excellent.

Comparative example 9
Using the composite film described in Comparative Example 2, aluminum was evaporated at a degree of vacuum of 1.3 × 10 ^-2 Pa with an ordinary roll-to-roll type vapor deposition machine to form the base layer of the composite film. An aluminum layer of 40 nm was formed on the surface (A) to obtain a laminated film. The laminated film has an oxygen permeability of 15 cc/(m ² · 24 hr · atm) at 23 ° C. and a humidity of 0%, a total light transmittance of 1.3%, and a gloss It had a hardness of 600%, and had good gas barrier properties, light shielding properties, and gloss properties, but was inferior in low-temperature sealing properties.

Comparative example 10
Using the composite film described in Comparative Example 7, aluminum was evaporated at a degree of vacuum of 1.3 × 10 ^-2 Pa with an ordinary roll-to-roll type vapor deposition machine to form the base layer of the composite film. An aluminum layer of 40 nm was formed on the surface (A) to obtain a laminated film. In this laminated film, since the surface of the base layer (A) of the composite film was rough due to the disturbance of the lamination interface between the base layer (A) and the heat seal layer (B), lamination unevenness of the aluminum deposition film occurred. The oxygen transmission rate of this laminated film was measured and found to be 60 cc/(m ² ·24 hr·atm) at 23°C and 0% humidity, a total light transmission rate of 10% and a glossiness of 450%. In this laminated film, since the surface of the base layer (A) layer is rough due to the disturbance of the lamination interface between the base layer (A) and the heat seal layer (B), the composite film has a high oxygen permeability and an aluminum vapor deposition film layer. The adhesiveness of the film was inferior, and the gas barrier properties, light shielding properties, and glossiness were also inferior.

Example 7
Using the composite film described in Example 2, aluminum was evaporated at a degree of vacuum of 1.3×10 ⁻² Pa with a conventional roll-to-roll vapor deposition machine, and oxidized while introducing oxygen. An aluminum deposition layer was formed to a thickness of 10 nm on the surface of the base layer (A) of the composite film to obtain a laminated film. The oxygen permeability of the laminated film was measured and found to be 48 cc/(m ² ·24 hr·atm) at 23°C and 0% humidity, indicating good gas barrier properties. Also, a laminate was produced on the produced aluminum oxide by the method described in Evaluation of Easy Adhesion, and the adhesion strength was measured. Adhesion strength was 2.1 N/15 mm, and easy adhesion was good. Moreover, it was excellent in low-temperature heat-sealability.

Example 8
Using the composite film described in Example 4, aluminum was evaporated at a degree of vacuum of 1.3×10 ⁻² Pa with an ordinary roll-to-roll vapor deposition machine, and oxidation was performed while introducing oxygen. An aluminum deposition layer was formed to a thickness of 10 nm on the surface of the base layer (A) of the composite film to obtain a laminate film. The oxygen permeability of the laminated film was measured and found to be 48 cc/(m ² ·24 hr·atm) at 23°C and 0% humidity, indicating good gas barrier properties. Also, a laminate was prepared by laminating a biaxially stretched polypropylene film on the prepared aluminum oxide by the method described in Evaluation of Easy Adhesion, and the adhesion strength of the deposited aluminum oxide layer was measured. Adhesion strength was 2.1 N/15 mm, and easy adhesion was good. Moreover, it was excellent in low-temperature sealability.

Comparative example 11
Using the composite film described in Comparative Example 2, aluminum was evaporated at a degree of vacuum of 1.3×10 ⁻² Pa with an ordinary roll-to-roll vapor deposition machine, and oxidized while introducing oxygen. An aluminum deposition layer was formed to a thickness of 10 nm on the surface of the base layer (A) of the composite film to obtain a laminated film. The oxygen permeability of the laminated film was measured and found to be 48 cc/(m ² ·24 hr·atm) at 23°C and 0% humidity, indicating good gas barrier properties. Also, a laminate was produced on the produced aluminum oxide by the method described in Evaluation of Easy Adhesion, and the adhesion strength was measured. Adhesion strength was 2.1 N/15 mm, indicating good easy adhesion, but poor low-temperature sealability.

Comparative example 12
Using the composite film described in Comparative Example 7, aluminum was evaporated at a degree of vacuum of 1.3×10 ⁻² Pa with a normal roll-to-roll vapor deposition machine, and oxidized while introducing oxygen. An aluminum deposition layer was formed to a thickness of 10 nm on the surface of the base layer (A) of the composite film to obtain a laminated film. In this laminated film, disturbance occurred at the laminated interface between the base layer (A) and the heat seal layer (B) of the composite film. This laminated film has a rough surface of the base layer (A) due to disturbance of the laminated interface between the base layer (A) and the heat seal layer (B), so the oxygen permeability at 23 ° C. and 0% humidity is was 78 cc/(m ² ·24 hr·atm), and the adhesion strength was 0.7 N/15 mm, indicating that the gas barrier property and the adhesion strength of the vapor-deposited aluminum oxide layer were inferior.

Example 9
As a lamination of the organic layer on the base layer (A) of the composite film of Example 2, the content of ethylene was 27 mol%, the degree of saponification was 99.8%, and the MFR was 4.0 g/10 min (under 2160 g load, 210 ° C.) of ethylene vinyl alcohol (hereinafter abbreviated as EVOH) (“EVAL” L171B manufactured by Kuraray Co., Ltd.) and an interfacial adhesive resin (hereinafter abbreviated as AD) (Admar QF500, manufactured by Mitsui Chemicals, Inc.). Separately melt-kneaded in separate extruders, using a 4-layer co-extruder, at an extrusion temperature of 220 ° C., 4 types of 4 layers of EVOH / AD / base layer (A) / heat seal layer (B) A multilayer film was obtained. Their thickness was 10 μm/5 μm/20 μm/5 μm respectively. The oxygen permeability of the laminated film was measured and found to be 5 cc/(m ² ·24 hr·atm) at 23°C and 0% humidity, indicating good gas barrier properties. Also, a laminate was produced on the produced EVOH by the method described in Evaluation of Easy Adhesion, and the adhesion strength was measured. The adhesion strength was 2.5 N/15 mm, indicating good adhesiveness and excellent low-temperature sealability.

Example 10
As lamination of the organic layer on the base layer (A) of the composite film of Example 4, the content of ethylene was 27 mol%, the degree of saponification was 99.8%, and the MFR was 4.0 g/10 min (under 2160 g load, 210 ° C.) of EVOH and AD are separately melt-kneaded in separate extruders and EVOH/AD/base layer (A)/heat seal layer ( A multilayer film of 4 types and 4 layers of B) was obtained. Their thickness was 10 μm/5 μm/20 μm/5 μm respectively. The oxygen permeability of the laminated film was measured and found to be 5 cc/(m ² ·24 hr·atm) at 23°C and 0% humidity, indicating good gas barrier properties. Also, a laminate was produced on the produced EVOH by the method described in Evaluation of Easy Adhesion, and the adhesion strength was measured. The adhesion strength was 2.5 N/15 mm, indicating good adhesiveness and excellent low-temperature sealability.

Comparative example 13
As a lamination of the organic layer on the base layer (A) of the composite film of Comparative Example 2, the content of ethylene was 27 mol%, the degree of saponification was 99.8%, and the MFR was 4.0 g/10 min (under 2160 g load, 210 ° C.) of ethylene vinyl alcohol (hereinafter abbreviated as EVOH) (“EVAL” L171B manufactured by Kuraray Co., Ltd.) and an interfacial adhesive resin (hereinafter abbreviated as AD) (Admar QF500, manufactured by Mitsui Chemicals, Inc.). Separately melt-kneaded in separate extruders, using a 4-layer co-extruder, at an extrusion temperature of 220 ° C., 4 types of 4 layers of EVOH / AD / base layer (A) / heat seal layer (B) A multilayer film was obtained. Their thickness was 10 μm/5 μm/20 μm/5 μm respectively. The oxygen permeability of the laminated film was measured and found to be 5 cc/(m ² ·24 hr·atm) at 23°C and 0% humidity, indicating good gas barrier properties. Also, a laminate was produced on the produced EVOH by the method described in Evaluation of Easy Adhesion, and the adhesion strength was measured. The adhesion strength was 2.5 N/15 mm, indicating good adhesiveness, but poor low-temperature sealability.

Comparative example 14
As lamination of the organic layer on the base layer (A) of the composite film described in Comparative Example 7, an EVOH layer/AD layer were laminated in the same manner as in Example 10 above. The oxygen transmission rate of the laminated film was measured and found to be 5 cc/(m ² · 24 hr · atm) at 23 ° C. and 0% humidity, indicating good gas barrier properties. A) The surface of the base layer (A) was rough due to disturbances at the lamination interface with the heat seal layer (B), and the adhesion strength of the EVOH layer was as low as 0.7 N/15 mm.

Example 11
In order to impart easy printability onto the base layer (A) of the composite film of Example 2, an organic/inorganic material was produced by the following method to obtain a laminated film.

<Organic component solution>
As the vinyl alcohol-based resin, modified polyvinyl alcohol containing a γ-butyrolactone structure having a carbonyl group in the cyclic structure (hereinafter sometimes abbreviated as modified PVA, degree of polymerization 1,700, degree of saponification 93.0%), The mixture was put into a solvent of water/isopropyl alcohol=97/3 by mass ratio, and heated and stirred at 90° C. to obtain an organic component solution having a solid content of 10% by mass.

<Inorganic component solution>
7.0 g of a 0.06N hydrochloric acid aqueous solution was added dropwise to a solution obtained by mixing 11.2 g of Ethyl Silicate 40 (an average pentamer ethyl silicate oligomer) manufactured by Colcoat Co., Ltd. as a linear polysiloxane and 16.9 g of methanol. to obtain a pentamer ethyl silicate hydrolyzate.

<Organic inorganic substance>
The modified PVA solution and the inorganic component solution are mixed and stirred so that the mass ratio of the solid content of the modified PVA and the solid content converted to _SiO2 (solid content mass of modified PVA/solid content mass converted to _SiO2 ) is 85/15. and diluted with water to obtain a coating liquid having a solid content of 12% by mass. This coating solution was applied onto the base layer (A) of the composite film described in Example 2 and dried to form a 0.4 μm-thick organic/inorganic substance, thereby obtaining a laminated film. This laminated film was evaluated for easy printability on a 5-grade scale, and was rated as 5th grade, which was good.

Example 12
In order to impart easy printability onto the base layer (A) of the composite film of Example 4, an organic/inorganic material was formed in the same manner as in Example 12 to obtain a laminated film. This laminated film was evaluated for ease of printing on a 5-grade scale, and the result was grade 5, which was good. Moreover, the low-temperature sealability was also excellent.

Comparative example 15
In order to impart easy printability onto the base layer (A) of the composite film of Comparative Example 2, an organic/inorganic substance was formed in the same manner as in Example 12 to obtain a laminated film. This laminated film was evaluated for ease of printing on a 5-grade scale, and was rated as 5th grade, which was good, but poor in low-temperature sealability.

Comparative example 16
In order to impart easy printability onto the base layer (A) of the composite film described in Comparative Example 7, an organic-inorganic mixture was formed in the same manner as in Example 12 to obtain a laminated film. Since the surface of the base layer (A) of this laminated film was rough, the easy printability was evaluated as grade 3, and the printability was poor.

By using the composite film of the present invention, there is little breakage and tunneling phenomena during heat sealing, good sealing performance, and excellent workability when laminating a function-imparting layer on the film surface. By laminating a function-imparting layer on the surface of the layer (A) and further laminating it on another base material to form a packaging laminate, it is possible to have a high degree of high-speed filling aptitude, and when packaging and filling, Excellent productivity is realized without causing troubles.

Claims (9)

A composite film having at least two layers, a base layer (A) and a heat seal layer (B),
The base layer (A) comprises 100 parts by mass of a propylene random copolymer (a1) having a melting point of 140° C. or higher and 1 to 1 high-density polyethylene (a2) having a melt flow rate at 190° C. of less than 10 g/10 minutes. Made of a resin composition mixed with 10 parts by mass,
The heat seal layer (B) mixes 100 parts by mass of a propylene random copolymer (b1) with 1 to 20 parts by mass of a high-density polyethylene (b2) having a melt flow rate of less than 10 g/10 minutes at 190°C. made of a resin composition,
The resin composition of the heat seal layer (B) has an extrapolated melting initiation temperature (Tim) of 110 ° C. or less by differential scanning calorimetry in JIS K 7121 (1987) and a melting point of 120 ° C. or more and 130 ° C. or less . the film. The propylene/random copolymer (a1) of the base layer (A) is an ethylene/propylene random copolymer, a propylene/1-butene random copolymer, or an ethylene/propylene/1-butene terpolymer. The composite film according to claim 1, which is one or more selected from the group consisting of: The propylene/random copolymer (b1) of the heat seal layer (B) is an ethylene/propylene random copolymer, a propylene/1-butene random copolymer, or an ethylene/propylene/1-butene terpolymer. The composite film of claim 1, which is one or more selected from the group consisting of coalescence. A biaxially oriented polypropylene film with a thickness of 20 μm or more is laminated on the composite film using an adhesive by a dry lamination method, and the heat seal layer (B) surfaces of the composite film are overlapped and one side is heated at 120 ° C. to heat seal. 2. The composite film according to claim 1, which has a heat seal strength of 6 N/15 mm or more when pressed. A laminated film comprising a base layer (A) of the composite film according to claim 1, and a function-imparting layer that imparts a specific function to the surface of the base layer (A). 6. The laminate film according to claim 5 , wherein the specific function is at least one selected from the group consisting of gas barrier properties, light shielding properties, glossiness, wettability, easy adhesion, and easy printability. 6. The laminated film according to claim 5 , wherein the oxygen permeability at 23[deg.] C. and 0% humidity is 50 cc/(m< ² >.24 h.atm) or less. A laminate obtained by laminating the laminated film according to claim 5 and another base material so that the function-imparting layer is on the side of the other base material. 9. The laminate according to claim 8 , wherein the other base material is a biaxially stretched polypropylene film using a polypropylene resin having stereoregularity of 90 to 98%.