JPH06262871A - Film for thermal stencil printing base paper - Google Patents

Abstract

PURPOSE:To obtain a thermal stencil printing base paper film realizing clear plate making and printing in both character and solid printing with remarkably improved sensitivity and resolving power. CONSTITUTION:As a thermal stencil printing base paper film, a polyester film made of at least two different kinds of polyesters compatible with each other is used. One of said polyesters, i.e., a polyester A, has a melting point Tm<=210 deg.C and a crystal melting energy DELTAHu>=4cal/g.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive stencil printing base paper film which is perforated by receiving heat from a xenon flash lamp or a thermal head. More specifically, it relates to a film for heat-sensitive stencil printing base paper, which has excellent perforation properties and sharpness at the time of printing.

[0002]

2. Description of the Related Art As a heat-sensitive stencil printing base paper, a film in which a heat-sensitive stencil printing base paper is bonded to a porous support with an adhesive is usually used. Vinylidene copolymer film, polypropylene film and polyethylene terephthalate copolymer film have been used, and thin paper, Tetoron gauze and the like have been used as the porous support (for example, JP-A-53-49519).

However, these conventional heat-sensitive stencil printing base papers have the following drawbacks. 1) When solid printing is performed, uneven printing is likely to occur. 2) Since the thickness unevenness is large and the flatness is poor, the suitability for lamination with the porous support is poor, and uneven printing is likely to occur. 3) Light and shade appear on the printed part, and a clear image cannot be obtained. 4) In addition, unevenness in the thickness of characters partially occurs. 5) No thin black characters appear, resulting in poor gradation. 6) The adhesive used for adhesion to the porous support causes a difference in sensitivity and resolution.

In general, when a plastic film is used as a film for heat-sensitive stencil printing paper, a sticking phenomenon occurs in which the film is partially fused to the thermal head by the heat given by the thermal head. When this phenomenon occurs, not only the film does not run smoothly, but also the thermal head is significantly contaminated and the sharpness at the time of punching is impaired. In addition, there is a problem that fusion with the document occurs when punching with a flash lamp.

Further, since the biaxially stretched polyester film is an insulator, it is significantly charged by static electricity, which may cause wrinkles or the like in post-processing or cause dusting or the like to cause perforation failure. Since the surface of the axially stretched polyester film is highly oriented, it has a drawback that the adhesiveness of the adhesive is poor. Further, since the film is thin, it has a drawback that the stretching stability is poor.

[0006]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned drawbacks, and clear both character printing and solid printing with high gradation and no printing unevenness, and stickiness prevention, easy adhesion and A stable film for heat-sensitive stencil printing base paper having excellent antistatic properties is provided.

[0007]

Means for Solving the Problems As a result of intensive studies for solving the above-mentioned drawbacks, the present inventors have found that a film obtained by mixing a polyester with a specific polyester is suitable as a film for heat-sensitive stencil printing base paper, The present invention has been completed.

That is, the film for heat-sensitive stencil printing base paper of the present invention is composed of at least two kinds of mutually compatible polyesters, one of which, polyester A, has a melting point Tm ≦ 210 ° C. and a crystal melting energy ΔHu.
It is characterized by using a polyester film of ≧ 4 cal / g.

In the present invention, the polyester is a polyester having a dibasic acid and glycol as constituent components,
Aromatic dibasic acids include terephthalic acid, isophthalic acid, phthalic acid, naphthalene dicarboxylic acid, diphenyl sulfone dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenoxyethane dicarboxylic acid, cyclohexane dicarboxylic acid, diphenyl dicarboxylic acid, diphenyl thioether dicarboxylic acid, diphenyl Examples thereof include ketone dicarboxylic acid, phenylindane dicarboxylic acid, sodium sulfoisophthalic acid and dibromoterephthalic acid. Examples of the alicyclic dibasic acid include cyclohexanedicarboxylic acid, decalin dicarboxylic acid and hexahydroterephthalic acid. Further, as the aliphatic dibasic acid,
Examples thereof include oxalic acid, succinic acid, adipic acid, azelaic acid, sebacic acid and dimer acid. Examples of the glycol include aliphatic glycols such as ethylene glycol, propylene glycol, tetramethylene glycol, hexamethylene glycol, neopentyl glycol and diethylene glycol, and aromatic diols include naphthalene diol and 2,2-bis (4-hydroxydiphenyl). ) Propane, 2,2-bis (4-hydroxyethoxyphenyl) propane, bis (4-hydroxyphenyl) sulfone, hydroquinone, tetrabromobisphenol A, etc., and alicyclic diols include cyclohexanedimethanol and cyclohexanediol. And so on.

Further, within the range in which the polyester is substantially linear, a trifunctional or higher-functional compound such as glycerin, trimethylolpropane, pentaerythritol,
Trimellitic acid, trimesic acid, pyromellitic acid, tricarballylic acid, gallic acid or the like may be copolymerized, or a monofunctional compound such as o-benzoylbenzoic acid or naphthoic acid may be added and reacted. Further, a polyether such as polyethylene glycol or polytetramethylene glycol or an aliphatic polyester represented by polycaprolactone may be copolymerized.

In the polyester of the present invention, the melting point T
m ≦ 210 ° C., crystal melting energy ΔHu ≧ 4 cal /
It is necessary to include g Polyester A. ΔHu is a measure of the crystallinity of the polymer, and this polyester A must have high crystallinity and have a melting point of 210 ° C. or less. As the polyester A, those having an aliphatic dibasic acid or glycol as a constituent component or a copolymer thereof are preferable, and examples thereof include polypentamethylene terephthalate, polyhexamethylene terephthalate, polyethylene adipate, polyethylene sebacate, and polycyclohexanediene. Examples thereof include methylene adipate, copolymers thereof, polybutylene terephthalate copolymer, polybutylene naphthalate copolymer and the like. Among these polyesters, at least selected from polyhexamethylene terephthalate or a copolymer thereof, polyethylene adipate or a copolymer thereof, and polybutylene terephthalate copolymer from the viewpoints of crystallinity, melt extrudability, film-forming property and the like. Polymers of one type are preferred.

The polyester of the present invention is composed of at least two different types of mutually compatible polyesters. Even if the polyesters have different constituents or are homopolymers and copolymers, they are "different polyesters". If the copolymerization components are the same, but the copolymerization ratio is different, they may be regarded as “different polyesters”. In any case, these polyesters are required to be compatible with each other, but the term “compatibility” in the present invention means that the unstretched film is transparent when the polyesters are mixed and melt-extruded. The internal haze of the unstretched film is preferably 10% or less, more preferably 5% or less, and further preferably 3% or less in terms of thickness of 100 μm. That is, it is desirable that the polyester be dispersed in a diameter of submicron order or less. In order to compatibilize polyester, a method of reducing the difference in the solubility parameter of the polymer, that is, a method of changing the structure of the polymer, a method of adjusting the viscosity of the polymer, a method of increasing the shearing force at the time of melt extrusion or a compatibilizer is used. The method of adding as 3 components etc. is mentioned.

The polyester B compatible with the polyester A having a low melting point and high crystallinity is preferably ΔTcg ≧ 60 ° C. or substantially amorphous.
Here, ΔTcg is a value represented by the difference Tc-Tg between the glass transition temperature Tg and the cold crystallization peak temperature Tc when the polymer is measured by a differential scanning calorimeter. ΔTcg
As polyester B having a temperature of ≧ 60 ° C., among the polyesters composed of the above-mentioned constituents, heat resistance, mechanical strength,
From the viewpoint of film-forming property, a polymer comprising at least one selected from polyethylene terephthalate, polycyclohexane dimethylene terephthalate, polyethylene naphthalate and / or copolymers thereof is preferable.

The substantially amorphous polyester means a polymer having a crystal melting energy ΔHu of 4 cal / g or less measured by a differential scanning calorimeter, or a crystal melting point not observed. To make the polymer amorphous,
It is desirable to introduce or copolymerize a flexible structure. Preferred polymers include polyethylene isophthalate, polyethylene terephthalate / isophthalate copolymer (isophthalate copolymerization rate of 20 mol% or more),
Examples thereof include a copolymer of polyethylene terephthalate and cyclohexanedimethanol (copolymerization ratio of cyclohexanedimethanol 20 to 60 mol%).

As the combination of the polyester A and the polyester B, a compatible combination is selected from the above polymers. Among them, the polyester A has hexanediol as a constituent component and the polyester B has a cyclohexane ring. It is preferable that With this combination, the crystallinity can be imparted to the polyester A, the heat resistance can be imparted to the polyester B, and the polyester A and the polyester B are likely to be compatible with each other. Among them, as preferable polymers, polyester A includes polyhexamethylene terephthalate, polyhexamethylene terephthalate / cyclohexanedimethanol copolymer, polyhexamethylene terephthalate / isophthalate copolymer, and the like, and polyester B includes polycyclohexanediphthalate. Examples thereof include methylene terephthalate / ethylene glycol copolymer and polycyclohexane dimethylene terephthalate / isophthalate copolymer.

The mixing ratio of polyester A and polyester B may be arbitrary, but A / B is preferably 1/9 to 6/4.
Is. Further, the third component or more polymers may be mixed.

Glass transition temperature T of polyester film
g is preferably 0 ° C. or higher, more preferably 30 ° C. or higher,
It is particularly preferably 40 ° C or higher. If the Tg is less than 0 ° C., the film will be difficult to handle, and the quality of the film will change over time, causing a problem that the laminate with porous thin paper, for example, curls. In particular, the higher the glass transition temperature of the polyester, which is the main component of the polyester to be mixed, is preferable in terms of film forming property or quality of the film.

In the present invention, the heat sensitive film preferably has a melting energy ΔHu of 3 to 12 cal / g, more preferably 5 to 10 cal / g. If the melting energy is less than 3 cal / g, it causes sticking with the base paper (original) and clear character printing is not possible. In addition, ΔH
By setting u to 5 cal / g or more, clear character printing becomes possible. On the other hand, when ΔHu exceeds 12 cal / g,
It becomes a character in which a missing portion is generated, resulting in poor expression of solid printing, sensitivity, and shading. In addition, ΔHu is 10 cal /
When it is less than or equal to g, the perforation time can be shortened and the productivity and quality are improved.

In the present invention, when the characteristics of the heat-sensitive film, that is, the center line average roughness, the maximum roughness and the number of protrusions are within the ranges described below, the effects of the present invention are more remarkably exhibited, which is preferable. In the present invention, the center line average roughness (Ra) of the heat-sensitive film is preferably 0.03 to 0.5 μm, more preferably 0.03 to 0.3 μm. Centerline average roughness is 0.0
If it is less than 3 μm, winding and handling will be quite difficult and creases will be formed, resulting in a decrease in productivity. Also, Ra is 0.5 μ
If it exceeds m, the surface becomes rough and becomes too opaque, resulting in a significant decrease in sensitivity.

In the heat-sensitive film of the present invention,
The maximum roughness (Rt) is preferably 0.3 to 4.0 μm, more preferably 0.3 to 3.5 μm. If the maximum roughness is less than 0.3 μm, the slipperiness will be poor, air will not escape easily, and vertical wrinkles will be included, and the winding performance will be poor. On the other hand, if it exceeds 4.0 μm, not only the sensitivity is lowered, but also the film is broken and the productivity is lowered.

In the present invention, the heat-sensitive film is 1 μmφ
The number of protrusions above is preferably 2,000 to 10,000 / mm ² .
More preferably, it is 2,500 to 8,000 pieces / mm ² . 2,000
If the number is less than 1 / mm ² , slipperiness and windability will deteriorate, and 10,000
When the number of particles / mm ² is exceeded, the transparency is lowered and the sensitivity and the resolution are lowered.

The number of projections of 8 μmφ to 20 μmφ is preferably 20 to 1,000 / mm ² , and more preferably 50.
~ 800 pieces / mm ² is good. If it is less than 20 pieces / mm ² , the slipperiness will be poor, and the film will meander during winding and the winding performance will be poor. If it exceeds 1,000 pieces / mm ² , not only the quality will be deteriorated but also the film will be broken and the productivity will be decreased.

In the present invention, in order to control the surface morphology of the heat-sensitive film, that is, the surface roughness, the number of protrusions, and the diameter of the protrusions within the above-mentioned preferable ranges, inert particles are used as the thermoplastic resin to be extruded in the production method described later. It is desirable to prepare a master polymer containing the above and blend it with the main polymer. In this case, the master polymer has a melting point of 0 to 100 ° C., preferably 20 to 80 ° C., as compared with the main component polymer.
Higher and / or higher intrinsic viscosity of 0.2 to 1.0 is preferable. Further, the main component polymer and the master polymer are preferably compatible with each other to some extent or more.
Furthermore, it goes without saying that the specific surface morphology can be controlled to some extent by the shear stress at the time of extrusion, the basis weight of the filter, the extrusion conditions and the like.

The inert particles used in the present invention include:
Particles selected from oxides or inorganic salts of elements of Group IIA, IIIB, IVA, IVB of the element period, for example, calcium carbonate obtained as a synthetic or natural product, wet silica (silicon dioxide), dry silica (silicon dioxide) , Aluminum silicate (kaolinite), barium sulfate, calcium phosphate, talc, titanium dioxide, aluminum oxide, aluminum hydroxide, calcium silicate and the like.

The average particle diameter of the above inert particles is 0.1 to 3 μm.
It is preferably m. Further, the master chip concentration of the inert particles is preferably 0.5 to 10% by weight, more preferably 1.0 to 7.0% by weight in order to form a specific surface morphology. The concentration of the inert particles in the heat-sensitive film varies depending on the type of particles, the particle size, etc., but is preferably 0.05 to 2.0% by weight, preferably 0.1 to 1.0% by weight in order to obtain a specific surface morphology.

In the present invention, an additive having an absorption peak in the wavelength range of flash light irradiation may be added to the heat-sensitive film. In addition, additives such as an antioxidant, a heat stabilizer, a lubricant, an antistatic agent, a dye and a pigment may be added if necessary. The film may have a structure of two or more layers, and inert particles or other additives may be added to either layer.
At that time, each layer may be coextruded or may be formed into a film by an extrusion laminating method or a coating method.

100-150 ° C. of polyester film
The heat shrinkage stress at 0.1 to 1.5 kg / mm ²
In the present invention, the heat shrinkage stresses at Tm-90 ° C and Tm-50 ° C are X (Tm-90 ° C) and X (Tm-5), respectively.
0 ° C.), it is possible to improve the perforation property because X (Tm−90 ° C.) <X (Tm−50 ° C.). When Tm has multiple peaks, the peak value on the high temperature side is taken as the value of Tm. At this time, the shrinkage stress may be an average in the longitudinal direction and the lateral direction of the film, or may be a value in either one of the directions. That is, when the shrinkage stress increases as the temperature rises in the process of abruptly raising the temperature of the film before it is perforated, the film perforates all at once near the perforation temperature.

Next, an example of the method for producing the polyester film of the present invention will be described, but the invention is not limited to such an example. The dried polymer chips are fed to an extruder and heated to a temperature above the melting point of the polymer to melt it. Next, the melted polymer is extruded from a slit-shaped T die and adhered to a cooling roll to be solidified to obtain a cast film. In order to improve the adhesion between the molten sheet and the cooling roll, the electrostatic application adhesion method and / or the liquid surface coating adhesion method are usually preferably used. The film is further biaxially stretched. Preferably, it is stretched 2.3 to 7 times in the longitudinal direction by rolls heated to a temperature not lower than the glass transition temperature of the polymer, for example 40 to 100 ° C., and then preferably in the transverse direction, preferably 45 to
It is stretched 3 to 7 times at 110 ° C. A method in which unidirectional stretching is performed in two or more steps can be used, but in that case also, the final stretching ratio is preferably within the above range. Moreover, the area ratio of the cast film is 6 to 30.
It is also possible to carry out simultaneous biaxial stretching so as to double the length.

The film thus obtained is heat-treated, but if necessary, it may be stretched again in the machine direction and / or the transverse direction before or after the heat treatment. Heat treatment temperature is 90-18
The temperature is 0 ° C., preferably 90 to 150 ° C., and the heat treatment time is usually 1 second to 5 minutes. The heat shrinkage rate can be adjusted under this heat treatment condition. Further, the cooling rate of the film after the heat treatment also affects the heat shrinkage property. For example, the heat shrinkage stress can be adjusted by quenching or gradually cooling the film after the heat treatment, or by providing an intermediate cooling zone.

If desired, the film may be coated. In the case of the present invention, a release layer may be provided on the film to impart sticking-preventing property and anti-adhesion property to the original, or adhesiveness to the porous support and antistatic property. The coating solution used is one dissolved in water, emulsified or suspended in view of explosion proof and environmental pollution.
The coating layer has a method of applying to a biaxially stretched film after completion of crystal orientation or a method of applying to a film before completion of crystal orientation and then stretching, but the latter method is required in order to more significantly exhibit the effect of the present invention. Is particularly preferable. The coating method is not particularly limited, but it is preferable to use a roll coater, a gravure coater, a reverse coater, a kiss coater, a bar coater or the like.

Before coating, the coating surface may be subjected to corona discharge treatment in air or other various atmospheres, if necessary. Further, the coating layer in the present invention, if necessary, a defoaming agent, a coating cross-linking agent, a thickener, an organic lubricant, inorganic particles, an antioxidant, an ultraviolet absorber, a foaming agent,
Dyes, pigments, etc. may be included. Furthermore, if necessary, inorganic particles may be added to the coating layer. Typical examples thereof are those having an average particle size of 1 μm or less, more preferably 0.5 μm or less, particularly preferably 0.2 μm or less, and specifically, kaolin, silica, silica sol,
Calcium carbonate, titanium oxide, barium salt, alumina,
Examples thereof include molybdenum sulfide, carbon black, and zirconium, but are not limited to these.

Further, the film of the present invention may be peeled off from a laminated film with another thermoplastic polymer (II) having excellent peelability to obtain a biaxially stretched thermoplastic film. By doing so, a thin film can be stably formed. The polymer (II) is any polymer selected from polyolefin, polyphenylene sulfide, fluorine-based polymer and the like.

The layer (II) has a peeling force of 10 g / cm or less when peeled from the film (I) of the present invention, preferably.
The effect of the present invention is remarkable when it is in the range of 0.1 to 2 g / cm, more preferably 0.2 to 0.8 g / cm. If the peeling force is too small, peeling between the film layers occurs during stretching or film transportation, uniform stretching cannot be performed, the film is stuck to the stretching roll, or the film peels off during film transportation, such as wrinkles or tears. Trouble may occur. On the other hand, if the peeling force is too large, the film cannot be peeled at a high speed and the film may be torn or pinholes may be formed. Therefore, in order to keep the peeling force within the above range,
It is preferable that 0.001 to 1% by weight, preferably 0.005 to 0.5% by weight, of a non-particulate lubricant is contained in the polymer, particularly in the (II) layer.

The non-particulate lubricant is a liquid at room temperature or a solid at room temperature, but has a melting point or softening temperature of 200 ° C.
The following substances may be used as long as they impart film lubricity, and specific examples are as follows. When two or more kinds of these substances are contained in the film, the total amount thereof should be within the above content range.

Specific examples of non-particulate lubricants include (1) aliphatic hydrocarbon liquid paraffin, microcrystalline wax, natural paraffin, synthetic paraffin, polyethylene wax,
Polypropylene wax etc.

(2) Higher fatty acid or metal salt thereof: stearic acid, calcium stearate, hydroxystearic acid, hardened oil, sodium montanate, etc.

(3) Aliphatic amides Stearic acid amide, oleic acid amide, erucic acid amide, ricinoleic acid amide, behenamide, methylenebisstearamide and the like.

(4) Fatty acid ester n-butyl stearate, methyl hydroxy stearate, myricyl serotinate, polyhydric alcohol fatty acid ester, ester wax and the like.

(5) Fatty acid ketone, ketone wax, etc.

(6) Fatty acid alcohol Lauryl alcohol, stearyl alcohol, myristyl alcohol, cetyl alcohol, etc.

(7) Partial ester of fatty acid and polyhydric alcohol Glycerin fatty acid ester, hydroxystearic acid triglyceride, sorbitan fatty acid ester and the like.

(8) Nonionic surfactant Polyoxyethylene alkyl ether, polyoxyethylene phenyl ether, polyoxyethylene alkylamide, polyoxyethylene fatty acid ester and the like.

(9) Silicone oil Linear methyl silicone oil, methylphenyl silicone oil, modified silicone oil, etc.

(10) Fluorine-based surfactant Fluoroalkylcarboxylic acid, perfluoroalkylcarboxylic acid, monoperfluoroalkylethyl phosphate, perfluoroalkyl sulfonate, etc.

Inorganic fine particles having an average particle size of 0.001 to 1 μm, for example, dry silica, wet silica, zeolite, calcium carbonate, calcium phosphate, kaolin, kaolinite, clay, talc, and oxidation are used in combination with the above non-particulate lubricant. Titanium, alumina, zirconia, aluminum hydroxide, etc. are added to the (I) layer and / or (II) layer in 0.0
If the content is 1 to 0.5% by weight, the effect of the non-particulate lubricant can often be synergistically enhanced.

The polyester film of the present invention thus obtained can be used as a heat-sensitive stencil printing base paper by laminating a predetermined porous thin paper with a known adhesive according to a conventional method.

[Measurement Method of Physical Properties and Evaluation Method of Effect] The characteristic values of the present invention are based on the following measurement methods and evaluation criteria. (1) Glass transition temperature, cold crystallization peak temperature, melting point, crystal melting energy (ΔHu) 10 mg of polyester was set in a differential scanning calorimeter (DSC-2 type) manufactured by PERKIN ELMER, and 20 ° C./under a nitrogen stream. The glass transition temperature was defined as the average value of the temperature at which the baseline began to become odd and the temperature at which the baseline returned to a new baseline, which was raised at a rate of min. Further, the peak of the exothermic peak due to crystallization was the cold crystallization peak temperature, and the peak of the crystal melting endothermic peak was the melting point. Regarding the crystal melting energy of polyester and polyester film, first, the area a of the crystal melting endothermic peak is obtained, indium is measured under the same DSC measurement conditions, and this area b = 3.6 ca.
It was calculated from the following formula as 1 / g. ΔHu (cal / g) = a / b × 6.8

(2) Heat Shrinkage A film sample of 100 mm square was set at a predetermined temperature (120
After immersing in silicone oil set to ℃) for 1 minute,
The amount of shrinkage of the film was obtained, and the ratio to the original size was expressed as a percentage.

(3) Heat shrinkage stress The film was sampled in a strip shape with a width of 10 mm, and the shrinkage force generated when the film was heated from room temperature to near the melting point of the film at a heating rate of 10 ° C./min was measured with a U-gauge. Then, the shrinkage stress curve with respect to temperature was obtained. The shrinkage stress at a predetermined temperature was determined from the curve.

(4) Practical characteristics of heat-sensitive stencil printing Washi paper of a film was stuck to prepare a base paper. The obtained base paper is applied with a thermal head at an applied energy of 0.0.
A character image and a 16-step gradation image were prepared at 9 mJ and 0.12 mJ. The perforated state of the gradation image portion was observed with a microscope from the film side of the plate-making base paper, and the following items were evaluated. (I) Perforation sensitivity ◯: Predetermined perforation is surely performed and is good. Δ: There is a part where the predetermined perforation cannot be obtained,
There is no problem in practical use. X: There are many places where a predetermined perforation cannot be obtained, which is a problem in practical use. (Ii) Independent perforation ○: Each dot is independently perforated. Δ: Perforations are formed almost independently, and there is no practical problem. X: Dots adjacent to each other are connected, which is a practical problem. In addition, the characters obtained by printing using a lithographic base paper and a lithograph AP7200 printing machine manufactured by Ideal Science Co., Ltd.,
The following characteristics of the image were visually evaluated. (Iii) Character printability In the presence or absence of missing characters, in terms of the presence or absence of uneven thickness of characters, those that are clearly unusable are marked with X, those that have no problems are marked with ○, and there are no missing or uneven thickness. Those that can be used are indicated by a triangle. (Iv) Evaluation of solid printability ● (circle filled in black) is 0.5, 1.
Using the base papers of 0, 3.0, 10.0 and 30.0 mmφ, the plate-made and printed ones were evaluated as follows. Correspondence with the base paper size of solid printing In the evaluation of uneven density of solid printing, those that are obviously unusable are marked with x.
Those with no problem are shown with a circle, and those with a problem but usable are shown with a triangle.

(5) Number of surface protrusions Al was vapor-deposited on the sample film to a thickness of about 100 nm to obtain an observation sample. This sample was examined with a microscope (reflection method) and an image analyzing computer "Quantime".
The size and the number of the protrusions were measured by an image (magnification: 358 times) obtained by enlarging the image using a t ″ 720 (Cambridge Instrument Co., Imanco) and providing contrast to the protrusions. The size is represented by the diameter (circle equivalent diameter) when the area occupied by the protrusions is converted into a circle.

(6) Center Line Average Roughness (Ra), Maximum Roughness (Rt) It was measured using a stylus type surface roughness meter according to JIS-B-0601. In addition, using a high precision thin film step measuring instrument (model: ET-10) manufactured by Kosaka Laboratory Ltd., stylus diameter cone type 0.5 μR, load 5 mg, cutoff 0.08.
mm.

(7) Intrinsic viscosity Measured at 25 ° C. using an o-chlorophenol solvent.

(8) Compatibility The internal haze of the unstretched sheet obtained by extruding the mixed raw materials was measured. Film haze is ASTM-D1
It was measured according to 003-52.

(9) Average particle size of particles Centrifugal sedimentation type particle size distribution analyzer SA- manufactured by Shimadzu Corporation
The particle size was measured by a sedimentation method based on the Stokes resistance law using CP3 type. The average particle diameter (d50) was obtained by using the value of 50% (according to weight) in the equivalent spherical distribution of the particles obtained by the measurement.

[0056]

EXAMPLES The present invention will be specifically described below based on examples. Example 1 Polyester A having an intrinsic viscosity of 0.85 was obtained by polymerizing by a conventional method using dimethyl terephthalate as a dicarboxylic acid component and hexamethylene glycol as a glycol component. Further, as a particle master, polyhexamethylene terephthalate containing 2% of silica particles having an average particle diameter of 1.2 μm was similarly prepared. As the polyester B, Kodar A-150 (trade name) manufactured by Eastman Kodak Co. using dimethyl terephthalate and dimethyl isophthalate as dicarboxylic acid components and 1,4-hexamethylenedimethanol as a glycol component was used.

Polyester A and polyester B were mixed in an amount of 30 parts by weight and 70 parts by weight, respectively, and a particle master was used so that the amount of particles was 0.2% by weight based on the total polymer. This mixed raw material was extruded into a sheet form at 280 ° C. from a vent type twin-screw extruder, and rapidly cooled and solidified on the rotating cooling drum whose surface temperature was set to 25 ° C. by using the electrostatic contact method, and the film was vertically oriented. It was stretched 3.3 times at 87 ° C. and 3.5 times at 92 ° C. in the transverse direction, and further heat-treated at 150 ° C. for 5 seconds to produce a film having a thickness of 2.0 μm.

Example 2 As the polyester A, the polyester A of Example 1 and its particle master were used. As the polyester B, PETG6763 (trade name) manufactured by Eastman Kodak Co., which uses dimethyl terephthalate as a dicarboxylic acid component and 1,4-hexamethylene dimethanol and ethylene glycol as a glycol component, was used.

Polyester A and polyester B were mixed in an amount of 30 parts by weight and 70 parts by weight, respectively, and a particle master was used so that the amount of particles was 0.2% by weight based on the total polymer. This mixed raw material was extruded into a sheet form at 280 ° C. from a vented twin-screw extruder, stretched to 85 ° C. 3.3 times in the longitudinal direction and 90 ° C. 3.5 times in the transverse direction as in Example 1, and further 110 Heat treatment at ℃ for 5 seconds, thickness 2.0μ
m film was produced.

Example 3 Dimethyl terephthalate as a dicarboxylic acid component, 1,4-cyclohexanedimethanol as a glycol component,
Polymerization by a conventional method using hexamethylene glycol,
The ratio of glycol components is 1,4-cyclohexanedimethanol / hexamethylene glycol: 50 mol% / 50
A copolyester A having a mol% and an intrinsic viscosity of 0.85 was obtained. As polyester B, Kodar A-150
Was used. The average particle size is 1.2μ as a particle master.
Polyethylene terephthalate containing 3% of m silica particles and having an intrinsic viscosity of 0.65 was similarly prepared.

A raw material prepared by mixing 30 parts by weight of polyester A, 70 parts by weight of polyester B, and 8 parts by weight of particle master was extruded into a sheet form at 280 ° C. from a vented twin-screw extruder, and the same as in Example 1 in the longitudinal direction. The film was stretched at 90 ° C. 3.3 times and transversely at 95 ° C. 3.4 times and further heat-treated at 150 ° C. for 5 seconds to produce a film having a thickness of 2.0 μm.

Example 4 As the polyester A, the polyester A of Example 1 and its particle master were used. Polyester B was polymerized by a conventional method using dimethyl terephthalate and dimethyl adipate as dicarboxylic acid components and ethylene glycol as glycol component, and the ratio of dicarboxylic acid component components was terephthalic acid component / adipic acid component: 80 mol% / 20. A copolymerized polyester B having a mol% and an intrinsic viscosity of 0.65 was obtained.

30 parts by weight of polyester A and 70 parts by weight of polyester B were mixed, and a particle master was used so that the amount of particles was 0.2% by weight based on the total polymer. Using this mixed raw material, a bent type twin-screw extruder was used to extrude a sheet at 280 ° C., and similarly to Example 1, 60 ° C. 3.3 times in the longitudinal direction and 65 ° C. 3.4 times in the transverse direction, Further heat treatment at 130 ℃ for 5 seconds, thickness 2.0μ
m film was produced.

Example 5 Polyester A was polymerized by a conventional method using dimethyl terephthalate and dimethyl isophthalate as the dicarboxylic acid component and 1,4-butanediol as the glycol component, and the ratio of the dicarboxylic acid component component was terephthalic acid component. / Isophthalic acid component: 70 mol% / 30 mol%, and a copolyester A having an intrinsic viscosity of 0.87 was obtained.

As polyester B, dimethyl terephthalate and dimethyl isophthalate as dicarboxylic acid components,
Polymerization was carried out by a conventional method using ethylene glycol as a glycol component to obtain a copolyester B having a dicarboxylic acid component ratio of terephthalic acid component / isophthalic acid component: 80 mol% / 20 mol% and an intrinsic viscosity of 0.65. .
As the particle master, the average particle size of 1.
A polyethylene terephthalate containing 3% of 2 μm silica particles and having an intrinsic viscosity of 0.65 was prepared.

Polyester A (30 parts by weight), polyester B (70 parts by weight) and particle master (8 parts by weight) were mixed and extruded into a sheet form at 280 ° C. from a vented twin-screw extruder. 90 ° C 3.3 times, 95 laterally
The film was stretched at a temperature of 3.4 ° C. and further heat-treated at 130 ° C. for 5 seconds to produce a film having a thickness of 2.0 μm.

Comparative Example 1 Only Kodar A-150 was extruded into a sheet form at 280 ° C. from a vented twin-screw extruder, and as in Example 1, 90 ° C. 3.3 times in the longitudinal direction and 95 ° C. in the transverse direction. Stretched 4 times,
Further, a heat treatment was performed at 130 ° C. for 5 seconds to obtain a film having a thickness of 2.0 μm, but the slipperiness of the film was extremely poor, and it was difficult to wind it into a roll.

Comparative Example 2 A sheet was formed in the same manner as in Comparative Example 1 using only PETG6763, and was 90 ° C. 3.3 times in the longitudinal direction and 95 ° C. 3.4 in the lateral direction.
The film was stretched twice and further heat-treated at 100 ° C. for 5 seconds to obtain a film having a thickness of 2.0 μm, but the slipperiness of the film was extremely poor and it was difficult to wind it into a roll.

Comparative Example 3 Polyethylene terephthalate containing 0.2% by weight of silica particles having an intrinsic viscosity of 0.75 and an average particle diameter of 1.2 μm was 2%.
Melt extruded at 80 ° C, stretched 89 ° C 3.3 times in the longitudinal direction and 93 ° C 3.8 times in the transverse direction, further heat-treated at 140 ° C for 5 seconds and cooled to produce a film with a thickness of 2.0 μm. did.

Comparative Example 4 As the polyester A, polyhexamethylene terephthalate having an intrinsic viscosity of 0.8 was used. As the polyester B and the particle master, the same raw materials as the polyester B and the particle master of Example 5 were used. 30 polyester A
Parts by weight, 70 parts by weight of polyester B and 8 parts by weight of particle master are mixed and melt-extruded from a vent type twin-screw extruder,
As in Example 1, 90 ° C. 3.3 times in the vertical direction and 9 in the horizontal direction.
The film was stretched at 5 ° C. to 3.4 times and further heat-treated at 130 ° C. for 5 seconds to obtain a film having a thickness of 2.0 μm.

The thus obtained film was laminated on a porous thin paper according to a conventional method to prepare a heat-sensitive stencil sheet, which was applied to a plate making machine and a printing machine, and its properties were evaluated.

[0072]

[Table 1]

In Examples 1 and 3 to 4, a polymer having ΔHu ≧ 60 ° C. was used as the polyester B, and in Examples 2 and 6, the polyester B was a substantially amorphous polymer. Is used. In any case, since the requirements of the present invention are satisfied, the film is excellent in handleability at the time of film production and at the time of making a base paper, and the base paper made using these is excellent in practical printing characteristics and excellent for heat-sensitive stencil printing. It was a thing.

On the other hand, Comparative Examples 1 and 3 have low perforation sensitivity and printability, and Comparative Example 2 has high perforation sensitivity, but the polymer melted by perforation blocks the perforated part again. The printability was not good. In Comparative Example 4, since the compatibility between the polyester A and the polyester B was poor, sufficient perforation did not occur and the printability was insufficient.

[0075]

The following excellent effects can be obtained by the film for heat-sensitive stencil printing base paper of the present invention. (1) Vivid plate making and printing are possible for both text and solid printing. (2) With letter and solid printing, it is possible to perform plate making and printing without unevenness in thickness and unevenness in density. (3) The sensitivity and resolution are significantly improved. In addition, the following effects can be obtained in terms of productivity. (4) It has excellent stretchability and enables long-term stable film formation. ◎ (5) It has excellent slipperiness and winding-up property, and can prevent wrinkles and stray winding, and can provide a film with good flatness and thickness uniformity.

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Claims (4)

[Claims] 1. A polyester film comprising at least two different types of mutually compatible polyesters, one of which, polyester A, has a melting point Tm ≦ 210 ° C. and a crystal melting energy ΔHu ≧ 4 cal / g. Characteristic film for heat-sensitive stencil printing base paper. 2. The film for heat-sensitive stencil printing base paper according to claim 1, wherein the polyester compatible with the polyester A is polyester B having ΔTcg ≧ 60 ° C. (Where ΔTcg = Tc−Tg, Tg: glass transition temperature, Tc: cold crystallization peak temperature). 3. The heat-sensitive stencil printing base paper film according to claim 1, wherein the polyester compatible with the polyester A is a substantially amorphous polyester B. 4. The polyester A having hexane diol as a constituent component, and the polyester B compatible with the polyester A having a cyclohexane ring. The film for heat-sensitive stencil printing base paper described in.