JP3453882B2 - Film for heat-sensitive stencil printing base paper - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film for heat-sensitive stencil printing base paper, which is perforated by receiving heat from a xenon flash lamp or a thermal head.

[0002]

2. Description of the Related Art As a heat-sensitive stencil printing base paper, a film obtained by laminating a heat-sensitive stencil printing base paper film and a porous support with an adhesive is usually used. As a heat-sensitive stencil printing base paper film, a vinyl chloride / vinylidene chloride is used. Copolymer films, polypropylene films and polyethylene terephthalate copolymers have been used. The film for heat-sensitive stencil sheet is preferably made thin from the viewpoint of perforation sensitivity, and when a polyester film is used for heat-sensitive stencil use, thinning is one of the very effective means. However, when a thin film is manufactured, it has a disadvantage that the stretching stability is poor because the film becomes thin. Therefore, there is a problem that unevenness in thickness and flatness are deteriorated, resulting in deterioration of perforation properties, suitability for lamination with a porous support, and uneven printing. Moreover, there was a problem that the productivity was lowered due to the blurring and that it was a burden on the workers as well.

[0003]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned drawbacks, to provide a film for heat-sensitive stencil sheet which is excellent in stretching stability, has small unevenness in thickness and good flatness.

[0004]

In the present invention, as a result of intensive studies for solving the above-mentioned drawbacks, it was found that a film obtained by copolymerizing a polyester with a specific component is suitable, and the present invention has been completed. .

The above-mentioned objects are as a dicarboxylic acid component,
It is composed of a copolyester containing 0.5 to 50 mol% of an aliphatic dicarboxylic acid, and the dicarboxylic acid component other than the aliphatic dicarboxylic acid is terephthalic acid / isophthalic acid = 50 /
It is achieved by the film for heat-sensitive stencil printing base paper, which is 50 to 95/5 (molar ratio ) and has a thickness unevenness in the width direction of 20% or less .

DETAILED DESCRIPTION OF THE INVENTION

In the present invention, the polyester is a polymer composed of a dicarboxylic acid component and a glycol component, and examples of the dicarboxylic acid component include terephthalic acid, isophthalic acid, phthalic acid, naphthalene dicarboxylic acid, diphenyl sulfone dicarboxylic acid, diphenyl ether dicarboxylic acid, Aromatic dicarboxylic acids such as diphenoxyethanedicarboxylic acid, cyclohexanedicarboxylic acid, diphenyldicarboxylic acid, diphenoxyethanedicarboxylic acid, 5-sodiumsulfoisophthalic acid, alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid, p-oxybenzoic acid, etc. And oxycarboxylic acid thereof. On the other hand, glycol components include ethylene glycol, butanediol, propanediol, pentanediol, hexanediol,
Aliphatic glycols such as neopentyl glycol, polyols such as polyethylene glycol, alicyclic glycols such as cyclohexane dimethanol, bisphenol A,
Examples thereof include aromatic glycols such as bisphenol S. Two or more kinds of these dicarboxylic acid components and glycol components may be used in combination.

The present invention is characterized in that an aliphatic dicarboxylic acid is copolymerized with the above polyester. In the investigation in the present invention, for example, as the dicarboxylic acid component,
Terephthalic acid / isophthalic acid = 50/50 to 95/5
It was found that when the (molar ratio) was used, the melting point and crystallinity of the polymer were lowered and the perforation sensitivity was improved. Here, if the molar ratio exceeds 50/50, problems such as difficulty in drying the polymer occur, and if the molar ratio is less than 95/5, the melting point and crystallinity are insufficiently lowered. However, although the improvement of the perforation sensitivity is recognized in this way, the stretching stability is poor, and therefore the location where the flatness decreases frequently and conversely the perforation property decreases,
There are problems such as uneven printing. However, it was found that a polymer obtained by copolymerizing a polymer with an aliphatic dicarboxylic acid has improved stretching stability and improved flatness, and uneven printing is eliminated, leading to the present invention.

The present invention is characterized in that an aliphatic dicarboxylic acid is copolymerized with the above polyester. From the viewpoint of stretching stability, aliphatic dicarboxylic acids having 8 or more carbon atoms are more preferable, and dimer acid is particularly preferable. Aliphatic dicarboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid as a long-chain aliphatic dicarboxylic acid having an alkylene group having 8 or more carbon atoms. , Undecadioic acid, dodecanedioic acid, tetradecadioic acid, eicoic acid, dimer acid, hydrogenated dimer acid, maleic acid, fumaric acid and the like and their derivatives.

The copolymerization ratio of the aliphatic dicarboxylic acid is 0.5 to 50 mol% with respect to the total acid component of the polyester. When the copolymerization ratio is less than 0.5 mol%, the stretching stability is hardly improved, and when the copolymerization ratio exceeds 50 mol%, the glass transition temperature Tg and the melting point Tm are greatly lowered, and problems such as adhesion during stretching are caused. Occurs, the strength of the film decreases, and the dimensional stability at room temperature decreases.

Polyesters may be copolymerized with polyfunctional compounds such as trimellitic acid, trimesic acid and trimethylolpropane, as long as the effects of the present invention are not impaired.

Glass transition temperature T of polyester film
g is preferably 0 ° C. or higher, more preferably 30 ° C. or higher, and even more preferably 40 ° C. or higher. If the Tg is less than 0 ° C., the handleability of the film deteriorates, the quality of the film changes over time, and a problem occurs, for example, that the laminate with porous thin paper curls.

The thickness unevenness of the polyester film in the present invention is 20% or less, preferably 15% in the width direction.
It is the following. If the thickness unevenness exceeds 20%, problems such as poor suitability for lamination with a porous support and poor perforation and print unevenness occur.

The melting point Tm of the polyester is preferably 230 ° C. or lower, more preferably 220 ° C. or lower. If the melting point exceeds 230 ° C., the thermal energy required for perforation increases, and the solid printing, the sensitivity, and the lightness and shade are poorly expressed.

The heat shrinkage of the polyester film in the present invention is preferably 5% or more in at least one direction in 140 ° C. in a hot air oven for 5 minutes. If the heat shrinkage rate is less than 5%, the perforability deteriorates, and the film cannot function as a heat-sensitive stencil sheet film.

The thickness of the polyester film in the present invention is preferably 10 μm or less, more preferably 5 μm or less, and further preferably 3 μm or less from the viewpoint of perforation sensitivity. If the thickness exceeds 10 μm, the energy required for perforation increases and the sensitivity becomes poor.

Further, other polyesters, other polymers or various additives may be added within the scope of the present invention. For example, known inorganic external particles such as kaolin, clay, calcium carbonate, silicon oxide, calcium terephthalate, aluminum oxide, titanium oxide, calcium phosphate, lithium fluoride as an inorganic lubricant and an organic lubricant for improving the slipperiness of a film. , Insoluble high-melting point organic compounds to be blended during melt film formation of polyester resin, and cross-linked polymers, and also formed inside polymers such as metal compound catalysts used in polyester production, such as alkali metal compounds or alkaline earth metal compounds There are internal particles.

In the present invention, the film may be added with an additive having an absorption peak in the wavelength range of flash light irradiation. 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 by an extrusion laminating method or a coating method.

The intrinsic viscosity, which is a measure of the molecular weight of the copolyester of the present invention, is preferably 0.4 or more, more preferably 0.5 or more, and if the intrinsic viscosity is less than 0.4, the film has a mechanical property. Strength tends to decrease.

Next, 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. The film is further biaxially stretched. Preferably,
Above the glass transition temperature of the polymer, eg 40-110 ° C
Stretched 2.3 to 7 times in the longitudinal direction with a roll group heated to
Then, it is stretched in the transverse direction preferably at 45 to 120 ° C. to 3 to 7 times. 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. It is also possible to simultaneously biaxially stretch the cast film so that the area ratio becomes 6 to 30 times.

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 ~ 200
C., preferably 90 to 180.degree. 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 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.

The film may be coated if necessary. In the case of the present invention, the heat-sensitive stencil film for poetry is provided with a release layer to impart sticking prevention property and fusion prevention property to the original document, or adhesiveness to the porous support and antistatic property. Good. A coating solution that is dissolved in water, emulsified or suspended is used in terms of explosion-proof property and environmental pollution. The coating layer has a method of coating a biaxially stretched film after completion of crystal orientation or a method of stretching after coating on a film before completion of crystal orientation, but the latter method is required to more significantly develop the effect of the present invention. Is particularly preferable. The coating method is not particularly limited, but a roll coater
Chromatography, gravure coater, reverse coater, kiss coater, preferably applied by using a bar coater.

Before coating, the coating surface may be subjected to corona discharge treatment in air or other various atmospheres, if necessary.

In the coating layer in the present invention, if necessary, a defoaming agent, a coating crosslinker, a thickener, an organic lubricant,
Inorganic particles, antioxidants, ultraviolet absorbers, foaming agents, dyes, pigments and the like may be contained.

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

[0027]

[Physical property measuring method and effect evaluating method] The physical property values of the present invention are based on the following measuring methods and evaluation criteria.

(1) Stretching stability The number of times the film was shaken when the film was formed for one day was evaluated.

◯: The number of shakes is 0 to 1 △: The number of shakes is 5 or less X: The number of shakes is 10 or less XX: The number of shakes exceeds 10.

(2) Thickness unevenness Regarding thickness unevenness in the width direction, KG6 manufactured by Anritsu Electric Co., Ltd.
Tensile speed 1.
A sample length of 1 m was measured at 5 m / min, and the value was calculated by the following formula.

Thickness unevenness (%) = [(HL) / A] × 100 where H is the maximum thickness, L is the minimum thickness, and A is the average thickness.

(3) Heat sensitive stencil printing Japanese paper was attached to a film having practical characteristics to prepare a base paper. The obtained base paper was applied with a thermal head at an applied energy of 0.1.
A character image and a 16-step gradation image were made at 2 mJ, and the character printability was evaluated.

(A) Presence / absence of characters (b) Presence / absence of uneven thickness of characters (a) and (b): Items markedly unusable are marked with x. The mark indicates that the sample was usable even though it was missing or had uneven thickness.

[0034]

EXAMPLES The present invention will be specifically described below based on examples.

Example 1 Polymerization was carried out by a conventional method using dimethyl terephthalate, dimethyl isophthalate, dimethyl dimerate as a dicarboxylic acid component, ethylene glycol as a glycol component, and silica particles having an average particle size of 1.2 μm to obtain a dicarboxylic acid component. A copolymerized polyester having a ratio of terephthalic acid component / isophthalic acid component / dimer acid component: 80 mol% / 18 mol% / 2 mol% and a silica particle addition amount of 0.2% by weight based on the produced polymer was obtained.

After the polymer was dried by a conventional method, it was supplied to an extruder, melt-extruded from a T-die and rapidly cooled and solidified on a cooling roll, and this film was longitudinally oriented at 90 ° C. for 3.1.
Double, transversely stretched at 95 ℃ 4.3 times, and 140 ℃
Heat treatment for 5 seconds, quench with cold air, thickness 2.0
A μm film was produced.

Example 2 The ratio of the dicarboxylic acid component was terephthalic acid component / isophthalic acid component / dimer acid component: 78 mol% / 18 mol% /
The thickness was 2.0 in the same manner as in Example 1 except that the amount was 4 mol%.
A μm film was produced.

Example 3 The ratio of the dicarboxylic acid component was terephthalic acid component / isophthalic acid component / dimer acid component: 74 mol% / 24 mol% /
A film having a thickness of 2.0 μm was produced in the same manner as in Example 1 except that the heat treatment temperature was 120 ° C. and the amount was 2 mol%.

Example 4 Dimethyl terephthalate and dimethyl dimerate as dicarboxylic acid components, ethylene glycol and 1,4-hexamethylene glycol as glycol components, average particle size 1.
Polymerization was carried out by a conventional method using 2 μm silica particles, the ratio of dicarboxylic acid component was terephthalic acid component / dimer acid component: 98 mol% / 2 mol%, and the ratio of glycol component was ethylene glycol / 1,4-hexamethylene. Glycol: 67 mol% / 33 mol%, silica particles were added in an amount of 0.2% by weight based on the produced polymer to obtain a copolymerized polyester, and a film having a thickness of 2.0 μm was produced in the same manner as in Example 1. .

Example 5 Dimethyl terephthalate, dimethyl isophthalate and dimethyl sebacate were used as the dicarboxylic acid component, and the ratio of the dicarboxylic acid component was terephthalic acid component / isophthalic acid component / sebacic acid component: 73 mol% / 24 mol% / 3 mol%
A film having a thickness of 2.0 μm was produced in the same manner as in Example 1 except that the above was adopted.

Comparative Example 1 Same as Example 1 except that dimethyl terephthalate and dimethyl isophthalate were used as the dicarboxylic acid component, and the ratio of the dicarboxylic acid component was terephthalic acid component / isophthalic acid component: 82 mol% / 18 mol%. And thickness 2.0 μm
A film was produced.

Comparative Example 2 Same as Example 1 except that dimethyl terephthalate and dimethyl isophthalate were used as the dicarboxylic acid component, and the ratio of the dicarboxylic acid component was terephthalic acid component / isophthalic acid component: 76 mol% / 24 mol%. And thickness 2.0 μm
A film was produced.

Comparative Example 3 Dimethyl terephthalate was used as the dicarboxylic acid component, ethylene glycol was used as the glycol component, 1,4-hexamethylene glycol, and silica particles having an average particle size of 1.2 μm were polymerized by a conventional method to obtain the glycol component. A copolymerized polyester having a ratio of ethylene glycol / 1, 4-hexamethylene glycol: 67 mol% / 33 mol% and a silica particle addition amount of 0.2% by weight with respect to the produced polymer was obtained, and treated in the same manner as in Example 1. To produce a film having a thickness of 2.0 μm.

Table 1 shows the results of evaluation of the characteristics of the film obtained above.

[0045]

[Table 1] As described above, in the examples as compared with the comparative examples, a film for heat-sensitive stencil sheet having excellent stretching stability can be obtained, and therefore, a film having good flatness and improved printing characteristics can be obtained.

[0046]

The film for heat-sensitive stencil sheet of the present invention provides the production of a film having good stretching stability and excellent flatness.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-246169 (JP, A) JP-A-5-246168 (JP, A) JP-A-6-183166 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) B41N 1/24 102

Claims (2)

(57) [Claims] 1. A dicarboxylic acid component comprising a copolyester containing 0.5 to 50 mol% of an aliphatic dicarboxylic acid, and the dicarboxylic acid component other than the aliphatic dicarboxylic acid is terephthalic acid / isophthalic acid = 50/50. ~ 95 /
A film for heat-sensitive stencil printing base paper, which is 5 (molar ratio ) and has a thickness unevenness of 20% or less in the width direction. 2. The film for heat-sensitive stencil printing base paper according to claim 1, wherein the aliphatic dicarboxylic acid is dimer acid.