JPH09156246A - Polyester film for thermal screen printing stencil paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain thermal screen printing stencil paper of favorable perforation properties by low energy, developing excellent gradation properties by providing the perforation diameter corresponding to a change in energy level and excellent in printing durability and curl resistance. SOLUTION: A polyester film for thermal screen printing stencil paper is composed of a biaxially stretched polyester film with a thickness of 0.2-5.0μm having an m.p. of 240 deg.C or lower and containing a magnesium element in an amt. of 10ppm more and satisfying formula M-P<=1.0 (wherein M/P is a mol ratio of the magnesium element and phosphorus element contained in the polyester film).

Description

Detailed Description of the Invention

[0001]

The present invention relates to a halogen lamp,
Regarding polyester film for heat-sensitive stencil printing base paper that is perforated by a xenon lamp, flash lamp, or other flash irradiation, infrared irradiation, pulsed irradiation with a laser beam, or a thermal head, especially perforation characteristics (perforation sensitivity, independent perforation), The present invention relates to a polyester film for heat-sensitive stencil printing base paper, which has excellent printing clarity (character printing, solid printing, gradation), printing durability and transportability (curl resistance).

[0002]

2. Description of the Related Art Conventionally, as a base paper for heat-sensitive stencil printing,
A thin paper made of a thermoplastic resin film such as vinylidene chloride film, polyester or polypropylene film, natural fiber, chemical fiber or synthetic fiber, or a mixture of these.
There is known a structure in which a porous support made of a non-woven fabric, gauze or the like is attached with an adhesive (for example, JP-A-51-2512 and JP-A-57-182495).
Issue publication). Films for these heat-sensitive stencil printing papers are perforated by a halogen lamp, a xenon lamp, a flash lamp or the like for flash or infrared irradiation, pulsed irradiation of a laser beam or the like, or a thermal head or the like, and ink is permeated through the above porous support. It becomes a printing plate that passes through.

However, in recent years, high resolution (gradation) is required for printed matter, and in order to obtain gradation in color in particular, the energy given to the head, that is, the temperature distribution of the head is changed. It has become necessary to be able to change the perforation diameter of the film. For that purpose, it is necessary to widely change the energy range to be applied to the above-mentioned thermoplastic film, small holes are perforated at low energy, large holes are perforated at high energy, and the holes are kept independent without being connected. (Independent perforation) is important.

On the other hand, in the printing method using a thermal head or the like, attempts have been made to reduce the size of each head and increase the number of heads per unit area in order to obtain high resolution. However, if you make the head smaller,
Even if the energy supplied to the head per unit area is the same as that of the conventional head, the life of the head is shortened. In order to make the life of the heads comparable to the conventional one, it is necessary to reduce the energy supplied to the individual heads, and it is necessary that the thermoplastic film described above be sufficiently perforated with low energy.

Further, it is necessary that the stencil sheet does not curl due to changes in temperature and humidity. If the curl becomes large, the stencil printing machine will not be easily conveyed in the stencil printing machine, and problems such as jamming of the stencil will occur.

Conventionally, as a film used for such a purpose, a film having improved printing characteristics and printing durability by controlling the thermal characteristics of a biaxially stretched polyester film (Japanese Patent Laid-Open No. 62-282984) and heat shrinkage characteristics. (Japanese Patent Application Laid-Open No. 62-282983, Japanese Patent Application Laid-Open No. 63-160895, Japanese Patent Application Laid-Open No. 1-97691).
Japanese Patent Laid-Open No. 1-168494, Japanese Patent Laid-Open No. 2-3
No. 07788, No. 3-30996, No. 3-99890, No. 3-288695, No. 3-182395, No. 4-125.
190, JP-A-4-185489, JP-A-4-224952, JP-A-5-77572, JP-A-6-305015, and JP-A-7-525.
No. 72, Japanese Patent Laid-Open No. 7-68964) and the like have been proposed.

[0007]

However, in the above-mentioned conventional techniques, the perforation sensitivity is not sufficient in the low energy region, and the independent perforation property is poor in the high energy region. There is a drawback such as a decrease. That is, the conventional film has a problem that the reaction with respect to the temperature is slow, although it is necessary to perforate by reacting sensitively to the difference in temperature.

The present invention solves the problems of the prior art, has good perforation performance even at low energy, and provides excellent gradation by opening a perforation diameter according to a change in energy level, and has excellent durability. An object of the present invention is to provide a film for heat-sensitive stencil printing base paper which is excellent in printing property and curling resistance.

[0009]

That is, the present invention provides a biaxially stretched polyester film having a thickness of 0.2 to 5 μm, wherein the polyester film has a melting point of 240 ° C. or lower and is contained in the polyester film. The polyester film for heat-sensitive stencil printing base paper is characterized in that the amount of elemental magnesium contained therein is 10 ppm or more and that the following formula is satisfied.

M / P ≦ 1.0 (where M / P represents the molar ratio of magnesium element and phosphorus element contained in the polyester film).

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The polyester used in the polyester film of the present invention is a polyester containing an aromatic dicarboxylic acid or an aliphatic dicarboxylic acid and a diol as main components. Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, phthalic acid,
1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,
4'-diphenyl dicarboxylic acid, 4,4'-diphenyl ether dicarboxylic acid, 4,4'-diphenyl sulfone dicarboxylic acid and the like can be mentioned. Examples of the aliphatic dicarboxylic acid include adipic acid, suberic acid, sebacic acid, dodecanedioic acid and the like. Of these, terephthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid are preferred. Examples of the diol component include ethylene glycol, 1,2
-Propanediol, 1,3-propanediol, neopentyl glycol, 1,3-butanediol, 1,4
-Butanediol, 1,5-pentanediol, 1,6
-Hexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-
Cyclohexane dimethanol, diethylene glycol,
Triethylene glycol, polyalkylene glycol,
2,2'bis (4'-β-hydroxyethoxyphenyl) propane and the like can be mentioned. Among them, ethylene glycol, 1,4-butanediol, 1,6-hexanediol, and 1,4-cyclohexanedimethanol are preferably used.

The polyester of the present invention may be copolymerized with components other than the dicarboxylic acid component and the diol component constituting the present invention, as long as the effects of the present invention are not impaired. Such components include trimellitic acid,
Examples thereof include polyfunctional compounds such as trimesic acid, pyromellitic acid, tricarballylic acid, trimethylolpropane, glycerin and pentaerythritol, and oxycarboxylic acids such as p-oxybenzoic acid.

The polyester used in the polyester film of the present invention is preferably polyethylene terephthalate, polybutylene terephthalate, polyhexamethylene terephthalate, polycyclohexane dimethylene terephthalate, polyethylene isophthalate, polyethylene-2,6-naphthalate, polybutylene-2, 6
Examples thereof include naphthalate, polyhexamethylene-2,6-naphthalate and the like, and copolyesters and blends thereof.

When the polyester of the present invention is used as a copolyester, the dicarboxylic acid component is terephthalic acid, isophthalic acid or 2,6-naphthalenedicarboxylic acid, and the diol component is ethylene glycol or 1,4-
Butanediol, 1,6-hexanediol, 1,4-
A polyester composed of cyclohexanedimethanol is preferable, and more preferably, one of terephthalic acid or 2,6-naphthalenedicarboxylic acid as a dicarboxylic acid component is 60 to 95 mol%, isophthalic acid is 5 to 40 mol%, and ethylene glycol or 1 is used as a diol component. , 4-
It is a polyester in which one of butanediol is 100 mol%, more preferably 70 to 90 mol% of one of terephthalic acid or 2,6-naphthalenedicarboxylic acid as a dicarboxylic acid component, and 10 to 30 isophthalic acid.
A polyester comprising 100% by mol of ethylene glycol or 1,4-butanediol as a diol component.

The polyester in the present invention can be produced by a conventionally known method. For example, a method in which a dicarboxylic acid component is directly esterified with a diol component and then the product of this reaction is heated under reduced pressure to polycondense while removing the excess diol component,
There is a method in which a dialkyl ester is used as a dicarboxylic acid component, a transesterification reaction is performed between this and a diol component, and then polycondensation is carried out in the same manner as described above. At this time, if necessary, a reaction catalyst can be appropriately used.

The polyester used in the present invention may be blended with various saturated polyester resins, polyolefins, polyamides, polycarbonates, polyethers and the like.

The polyester used in the present invention includes
If necessary, a flame retardant, a heat stabilizer, a plasticizer, an antioxidant, an ultraviolet absorber, an antistatic agent, a pigment, a fatty acid ester, an organic lubricant such as wax or a defoaming agent such as polysiloxane may be added. Also, two or more of these may be used in combination.

Further, if necessary, slipperiness can be imparted. The method for imparting slipperiness is not particularly limited, but for example, clay, mica, titanium oxide, calcium carbonate, kaolin, talc, inorganic particles such as wet or dry silica, acrylic acid-based polymers, polystyrene and the like as constituent components. A method of blending organic particles and the like, a catalyst added during the polyester polymerization reaction is deactivated and formed,
There are a so-called internal particle method and a method of applying a surfactant.

M / P in the polyester film of the present invention
(Here, M / P represents the molar ratio of the magnesium element and the phosphorus element contained in the polyester film.) Is 1.0 or less, preferably 0.05 to 1.0, and more preferably 0. It is 1 to 0.9. When M / P exceeds 1.0, improvement in perforation sensitivity and curl resistance cannot be obtained.

Further, the amount of elemental magnesium contained in the polyester film of the present invention is required to be 10 ppm or more, preferably 30 ppm or more, more preferably 50 ppm or more. When it is less than 10 ppm, the improvement of perforation sensitivity is not sufficient, and when a magnesium compound is used as a catalyst in polyester production, foreign matter is generated in the polyester, which is not preferable.

The amount of elemental phosphorus contained in the polyester film is preferably 10 ppm or more, more preferably 30 ppm or more, and particularly preferably 50 ppm or more. If it is less than 10 ppm, the heat resistance of the polyester is lowered, and due to the thermal deterioration of the polyester during melt extrusion,
The production stability of the film may not be maintained.

The method of adding the magnesium element and the phosphorus element in the present invention is not particularly limited, but the magnesium element is a hydride used as a catalyst for transesterification reaction, esterification reaction, polycondensation reaction, or for producing precipitated particles, It is preferably in the form of alcoholates, chlorides and monocarboxylates, more preferably in the form of acetates or chlorides. In addition, the phosphorus element is phosphoric acid,
It is preferably in the form of one or more phosphorus compounds selected from the group consisting of phosphorous acid, phosphonic acid, phosphinic acid or their esters and half esters, and especially from the group consisting of phosphonic acid or its esters and half esters. It is preferably in the form of one or more selected phosphorus compounds. In the present invention, the reason why the perforation sensitivity and the printing clarity are improved and the curl resistance is excellent is not clear,
By setting M / P in the polyester to a specific amount, crystal nuclei are generated inside the film, and by stretching in the state of microcrystals, the amorphous chains inside the film are highly oriented, and the glass transition temperature or higher. The perforation sensitivity is improved by greatly improving the heat shrinkage property at high temperature of, and further, the amorphous chains of the obtained biaxially stretched film are pseudo-crystallized by the scattered crystal nuclei and have a glass transition temperature of It is presumed that the curl resistance is improved as a result of suppressing the heat shrinkability at low temperatures.

The polyester film of the present invention may be formed by any of the following methods: inflation simultaneous biaxial stretching method, stenter simultaneous biaxial stretching method, and stenter sequential biaxial stretching method. From the viewpoint of the property, the stenter sequential biaxial stretching method is preferable.

The thickness of the polyester film of the present invention is
It should be 0.2 to 5 μm. The film thickness is 0.
When the thickness is less than 2 μm, the perforation sensitivity is improved in the low energy region, but the printing durability is poor, the film-forming stability and the winding property are deteriorated in the production of the film, and the obtained film and a porous support such as a thin paper. Also in the laminating process with, the yield becomes worse. On the other hand, when the film thickness exceeds 5 μm, the perforation sensitivity is poor and the printing clarity is reduced. A more preferable thickness is 0.3 to 2.5 μm, and a particularly preferable thickness is 0.5 to 2 μm.

The biaxially stretched polyester film of the present invention has a longitudinal refractive index (nMD) and a transverse refractive index (nMD).
The sum of (TD) (nMD + nTD) is preferably 3.2 or more. Furthermore, nMD + nTD is more preferably 3.25 or more, and particularly preferably 3.28 or more. By stretching and orienting the film in such a range, a printed matter having good perforation characteristics at low energy and excellent gradation can be obtained. nMD + nTD is 3.2
In the case of less than, the shape of the perforations is not stable, not only unperforated parts frequently occur in perforation with low energy, but also adjacent perforation parts with high frequency even in perforations with high energy, resulting in high printing clarity. May get worse.

Further, when the refractive index in the longitudinal direction (nMD) and the refractive index in the width direction (nTD) are the same value, the shape of the perforations tends to extend in the longitudinal direction of the film. That is, in the polyester film of the present invention, the shape of the perforations is close to a perfect circle, and the upper limit energy level that can maintain the independent perforation property is increased, and in order to widen the appropriate range of the perforation energy, it is preferable that the following relationship is satisfied. .

NMD ≦ nTD

The melting point of the polyester film of the present invention must be 240 ° C. or lower, and preferably 230
It is below ° C. A film having a melting point of more than 240 ° C. requires a large amount of energy for perforation, resulting in poor perforation characteristics at low energy.

The crystal melting energy (ΔHu) of the film of the present invention is preferably 12 to 46 J / g, more preferably 21 to 42 J / g. If the crystal melting energy of the film is less than 12 J / g, the perforated shape of the film may not be stable and clear character printing may not be obtained.
Further, the printing durability tends to deteriorate. On the other hand, 46 J / g
If it exceeds, a large amount of energy is required to melt the crystals inside the film, so that perforation at low energy tends to be poor.

Further, when the surface characteristics of the film obtained in the present invention, that is, the center line average roughness and the maximum roughness are within the ranges described below, the effects of the present invention are more remarkably exhibited, which is preferable.

The centerline average roughness (Ra) of the biaxially stretched film in the present invention is preferably 0.01 to 0.5 μm, and stable productivity, perforation characteristics, and printing sharpness in the process of forming a base paper from film formation. And more preferably 0.05 to 0.4
μm. When Ra is less than 0.01 μm, the winding property and the handling property become difficult, and creases may be formed, which may reduce the productivity. On the other hand, when Ra exceeds 0.5 μm, the roughening of the surface is so large that the perforation sensitivity is significantly reduced, and the target perforation diameter may not be obtained.

The maximum roughness (Rt) of the biaxially stretched film in the present invention is preferably 0.3 to 5 μm, more preferably 0.5 to 4 μm. When Rt is less than 0.3 μm, slipperiness is deteriorated, air bleeding is poor, and vertical wrinkles are formed.
Winding up and handling may be reduced. On the other hand, Rt is 5
If it exceeds μm, not only the roughening of the surface is so large that the perforation sensitivity is lowered, but also the film is broken and the productivity may be lowered.

The biaxially stretched polyester film of the present invention can be produced by a conventionally known method using the above polyester. For example, an unstretched film can be produced by extruding a polymer onto a cast drum by the T-die extrusion method. Slit width of the base,
By adjusting the discharge amount of the polymer and the rotation speed of the cast drum, an unstretched film having a desired thickness can be produced.

The intrinsic viscosity of the polyester used in the polyester film of the present invention is usually preferably 0.5 or more, more preferably 0.6 or more. Intrinsic viscosity is 0.
When it is lower than 5, the film-forming stability is lowered, and it is particularly difficult to cast a thin material.

The stretching method is not particularly limited, but the stretching in the longitudinal direction is performed by the following formula: Tg≤Tmd≤Tg + 25 (where Tg is the glass transition temperature (° C) of the resin constituting the film, and Tmd is the stretching temperature (° C)). It is preferable that the film is stretched in a highly oriented manner by performing it in the temperature range (Tmd) indicated by (1). A more preferable stretching temperature is in the range of Tg ≦ Tmd ≦ Tg + 20, and most preferably Tg ≦ Tmd ≦ Tg + 15. If the stretching temperature is lower than Tg, uneven stretching may occur, and stable film formation may be difficult. On the other hand, when the stretching temperature is higher than Tg + 25 (° C.), the orientation of the film by stretching does not proceed so much, and the effect of improving the perforation characteristics of the present invention may not be seen.

Further, as a preferred stretching method, if the unstretched film is once cooled to Tg or less and stretched in the longitudinal direction at the above stretching temperature, the orientation is more remarkably promoted.
desirable.

Furthermore, it is preferable that the unstretched film is held at a temperature in the crystallization temperature range of the polyester for 0.5 to 60 seconds and then stretched in the longitudinal direction at the stretching temperature described above because the orientation becomes more remarkable. .

The stretching ratio in the longitudinal direction is not particularly limited and may be appropriately determined depending on the kind of the polyester film polymer used and the sensitivity required for the film, but is usually about 2 to 5 times. .

Stretching in the width direction is not particularly limited, but after stretching in the longitudinal direction, heat treatment is performed once at a temperature of 100 ° C. or lower to a melting start temperature of the used polyester for 0.5 seconds or more, Further, the orientation is significantly advanced, which is preferable.

The stretching ratio in the width direction is not particularly limited and is appropriately determined depending on the kind of the polymer for polyester film to be used, the sensitivity required for the film, etc., but usually about 2 to 5 times is appropriate. .

After biaxial stretching, the longitudinal direction or width direction of the film, or both of them may be re-stretched.

Further, it is preferable to subject the film of the present invention after biaxial stretching to a heat treatment. The heat treatment temperature is a temperature above the glass transition point (Tg) of polyester and the time is 0.5
It is preferably carried out for 60 seconds.

In the polyester film of the present invention, the base paper for printing can be manufactured all at once by co-stretching in a state where the porous support is thermocompression bonded. By integrally stretching the film and the support in a thermocompression-bonded state, the porous support serves as a reinforcing body, the film is not broken, and the film formation stability is extremely excellent. It is preferable because a low-cost base paper can be obtained.

Further, in order to improve the film forming stability, a method of obtaining a biaxially stretched film by separating and separating from a laminated film with another thermoplastic polymer can be adopted.

The other thermoplastic polymer is not particularly limited, but preferably has a peeling force of 10 g / cm or less, more preferably 0.1 to 2 g / cm, further 0 when peeling from the polyester film layer of the present invention. .2 to 0.8 g / cm
It is preferred that More specifically, as long as it is different from the polyester constituting the polyester film of the present invention, specifically, polyester, polyamide, polyolefin, polystyrene, polycarbonate, polyacrylonitrile, polyvinyl alcohol, polyphenylene sulfide, polyacetal, Polyether, copolymers thereof, fluoropolymers and the like can be used. Among them, polyolefin, polyphenylene sulfide, fluorine-based polymer and the like are preferable. Typical examples of the polyolefin include low density polyethylene, medium density polyethylene, high density polyethylene, low density polyethylene, polypropylene, polybutene-1, poly-4-.
Methyl-pentene-1, or copolymers or mixtures thereof can be used, but propylene is 80 to 97.
Mol% and olefins other than propylene 3 to 20 mol%
Is more preferable. Further, in these polyolefins, various known release agents, for example, silicone,
Petroleum resin, terpene resin, higher fatty acid wax, etc. may be added. Furthermore, various known additives, for example,
An antioxidant, an antistatic agent, a coloring pigment, an antiblocking agent, an ultraviolet absorber, etc. may be added.

Specifically, as a method of peeling and separating to obtain a biaxially stretched film, the polyester used in the polyester film of the present invention and another thermoplastic polymer are supplied to different extruders respectively, and after fusion, they are combined in a die. Crimping, forming into a sheet, and extruding into a cast drum to produce an unstretched film. At this time, an unstretched film having a desired thickness can be produced by adjusting the slit width of the die, the discharge amount of the polymer, and the rotation speed of the cast drum. At this time, the polyester (referred to as A) constituting the biaxially stretched polyester film of the present invention and another thermoplastic polymer (referred to as B) have a two-layer structure of A / B or A / B.
Any of the B / A three-layer structure may be adopted. The unstretched film thus obtained can be obtained as a biaxially stretched film in the same manner as in the above-mentioned single layer film formation. After that, the target film of the (A) layer can be obtained by peeling the (A) layer and the (B) layer. At this time, the porous support may be attached and then peeled.

In the polyester film of the present invention, in order to prevent fusion with a thermal head or the like, a release agent can be applied to one surface of the polyester film before or after the film is stretched, or during the process. . The coating method is not particularly limited, but it is preferable to use a roll coater, a gravure coater, a reverse coater, a bar coater or the like.

If necessary, the coated surface may be subjected to corona discharge treatment in air or other various atmospheres before coating.

As the release agent used in the release agent layer of the polyester film of the present invention, a conventionally known release agent made of silicone oil, silicone resin, fluorine resin, surfactant or the like can be used. The following release agents are particularly preferable. That is, a release agent containing a mixture of a petroleum wax (a), a vegetable wax (b) and an oily substance (c) which is dissolved, emulsified or suspended in water as a main component is particularly preferable. Here, the main component means that the weight ratio of the mixture of (a), (b) and (c) is 50% or more, preferably 60% or more. The wax composition is a commercially available wax, for example, a petroleum wax, a plant wax, a mineral wax,
Animal waxes Low molecular weight polyolefins and the like can be used, and the petroleum waxes include, but are not particularly limited to, paraffin wax, microcrystalline wax, and oxidized wax. Examples of vegetable waxes include candelilla wax, carnauba wax, wooden wax, oliqury wax, sugar cane wax and rosin modified wax. Petroleum wax / vegetable wax mixed weight ratio is 10 /
90-90 / 10, preferably 20 / 80-80 / 2
0, and more preferably 30/70 to 70/30.
A vegetable wax content of 10% by weight or more is effective for imparting slipperiness and releasability at high temperatures, and for obtaining a uniform coating film having good dispersibility when emulsified or suspended in water. Because it is suitable. Further, when a mixture is prepared by further adding an oily substance to the above wax-based composition, the printing runnability can be made particularly excellent. Here, the oily substance is a liquid or paste-like oil at room temperature, and examples thereof include vegetable oils, fats and oils, mineral oils, synthetic lubricating oils and the like. As vegetable oil, linseed oil, kaya oil, saffron oil, soybean oil, cinnamon oil, sesame oil, corn oil, rapeseed oil, tuna oil, cottonseed oil, olive oil, southern oil, camellia oil, castor oil, peanut oil, balm oil,
For example, coconut oil. Fats and oils include beef tallow, pork oil, sheep oil, cocoa oil, and the like, and mineral oils include machine oil, insulating oil, turbine oil, motor oil, gear oil, cutting oil, liquid paraffin, and the like. As the synthetic lubricating oil, those satisfying the requirements described in the Chemical Dictionary (Kyoritsu Publishing Co., Ltd.) can be arbitrarily used, and examples thereof include olefin polymerized oil, diester oil, polyalkylene glycol oil, and silicone oil. . Among these, mineral oil and synthetic lubricating oil, which have good running properties in the high pulse width region, are preferable. Also, a mixed system of these may be used.

The above oily substance is preferably added in an amount of 1 to 100 parts by weight, more preferably 3 to 50 parts by weight, based on 100 parts by weight of the wax composition. If the amount of the oily substance is less than 1 part by weight, the running property in a high pulse width region such as that of a sublimation printer tends to decrease, and
On the other hand, if the amount exceeds 100 parts by weight, the running property in the low pulse width region tends to decrease. The above range is particularly preferable because stickiness does not occur in a printer having a wide pulse width and the running property is good.

Various additives may be used in combination in the above composition within a range that does not impair the effects of the present invention. For example, antistatic agents, heat-resistant agents, antioxidants, organic and inorganic particles,
Examples include pigments.

The thickness of the release agent layer is preferably 0.005 μm.
m or more and 0.4 μm or less, and more preferably 0.01 μm or more and 0.4 μm or less. The release agent layer has a thickness of 0.4 μm
If it is below, the running property at the time of punching is good and the contamination of the head is small.

[0053]

[Evaluation Method of Physical Properties and Effects] Each characteristic used in the present invention was measured and evaluated by the following methods.

(1) Measurement of melting point, glass transition temperature, crystallization temperature region, melting start temperature Differential scanning calorimeter RDC220 manufactured by Seiko Instruments Inc.
Using a mold, 5 mg of a film sample was sampled, and the melting point was determined from the peak temperature of the endothermic curve when the temperature was raised from room temperature at a rate of 20 ° C./min. When there are two or more peaks in the endothermic curve, the peak temperature of the one having the relatively larger endothermic curve area was taken as the melting point. The melting start temperature was determined as the temperature rising from the baseline (low temperature side) in the endothermic curve. In the glass transition temperature and crystallization temperature regions, the film sample was heated to 280 ° C., held at 280 ° C. for 5 minutes, then rapidly cooled with liquid nitrogen, and heated again from room temperature at a heating rate of 20 ° C.
The temperature was raised at a rate of 1 / min for measurement.

(2) Metal Analysis in Film Quantitative analysis of magnesium element was carried out by atomic absorption spectrometry, and quantitative analysis of phosphorus element was carried out by fluorescent X-ray analysis.

(3) Crystal Melting Energy of Film (ΔHu) Determined from the area of the film when melted using a differential scanning calorimeter RDC220 type manufactured by Seiko Denshi KK This area is shifted from the baseline to the absorption side by increasing the temperature, and is the area until the temperature returns to the baseline position when the temperature is further increased.The area from the melting start temperature position to the end position is connected by a straight line. (A) is obtained. In (indium) is measured under the same DSC conditions, and the area (b) is determined as 28.5 J / g by the following equation.

ΔHu = 28.5 × a / b (J / g)

(4) Measurement of Refractive Index of Film According to the method specified in JIS-K7105, the D-ray was measured with an Abbe refractometer as a light source. The mount solution used was methylene iodide, and
It measured at 65 degreeC and 65% RH.

If the film thickness is small and it is difficult to accurately obtain the value of the refractive index with Abbe's refractometer,
It was measured by the in-merge method using a polarization microscope.
As a standard solution with a known refractive index, liquid ventlactam and α
A mixed solution of chlornaphthalene was used.

(5) Center Line Average Roughness (Ra), Maximum Roughness (Rt) It was measured using a stylus type surface roughness meter according to JIS-B0601. In addition, using a high precision thin film step measuring instrument (model: ET-10) manufactured by Kosaka Laboratory Ltd., a conical stylus diameter of 0.5 μmR, a load of 5 mg, and a cutoff of 0.08 mm.
And

(6) Intrinsic viscosity After the sample was dried at 105 ° C. for 20 minutes, 6.8 ± 0.00
5 g is weighed, and 160 ° C. × 1 in o-chlorophenol.
It was dissolved by stirring for 5 minutes. After cooling, the temperature is set to 25 ° C by an AVM-10S type automatic viscosity meter manufactured by Yamatrabotik Co., Ltd.
Was measured.

(7) Measurement of stretching temperature Non-contact infrared thermometer THI-30 manufactured by Tasco Japan Co., Ltd.
Using 0, the average value of 10 points was taken as the measured value.

(8) Film Thickness (μm) 10 arbitrary spots of the sample were cut out in the cross-sectional direction, and 10 photographs were taken with an electron microscope at a magnification of 2000 to measure the film thickness. This was performed for 10 photographs and expressed as the average value.

(9) Punching characteristics The prepared base paper is "RISOGRA" manufactured by Ideal Science Co., Ltd.
It was supplied to the PH "RC115, and a plate of 10 mmφ was manufactured as a manuscript with JIS first level ● (circle filled in black) by a thermal head type plate making system (400 dpi). The energy to be applied to each dot is 50μJ, 40μJ, 30
There were 5 types of μJ, 20 μJ, and 10 μJ. Perforation was performed in this state, and 200 perforated portions of the film were observed with a scanning microscope at a magnification of 100 times, and the perforation characteristics were evaluated by the following items.

[Perforation sensitivity] ⊚: Predetermined perforation was surely performed and was good ○: There was a small portion where the predetermined perforation was not obtained, but there was no problem in practical use Δ: Predetermined in some places There was a part where the perforation could not be obtained. ×: The predetermined perforation was not obtained at all.

[Independent perforation] ⊚: each dot was independently perforated and was good ∘: Only a small portion of each dot was not independently perforated, but practically No problem △: There were parts where dots were not independently punched in some places. ×: Dots were connected in many areas next to each other.

(10) Vividness of printing Test chart No. manufactured by Ideal Science Co., Ltd. 8 as a manuscript, a base paper prepared using a thermal head of 400 dpi was prepared, and a printing sample was prepared using black ink.
The following characteristics of the image (solid printing) were visually observed and judged.

[Clearness of character printing] ○: No character loss or uneven thickness Δ: Missing character, uneven thickness but no problem in practical use ×: Missing character, uneven thickness Unavailable

[Clearness of solid printing] ○: There is no unevenness in light and shade and white spots Δ: There is unevenness in light and shade and white spots, but there is no problem in practical use ×: There is unevenness in light and shade and white spots and cannot be used

(11) Evaluation of Printing Durability It is represented by the number of sheets that can be printed before the film is broken by a printing machine. If it is 1000 or more, there is no problem in practical use.

(12) Evaluation of curl resistance The prepared stencil paper was treated for 1 week at 50 ° C. in a thermo-hygrostat having a humidity of 90% RH, and then a carrying test of the paper was conducted using a printing machine. It was evaluated according to the standard.

◯: Good curl although there is some curl ×: Large curl, frequent transfer troubles

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【Example】

Example 1 78.7 parts by weight of dimethyl terephthalate, 17.3 parts by weight of dimethyl isophthalate, 61.3 parts by weight of ethylene glycol, 0.086 parts by weight of magnesium acetate as a transesterification reaction catalyst, and antimony trioxide as a polycondensation reaction catalyst. 0.029 parts by weight, and "Irganox" 1010 (manufactured by Ciba-Gaiki Co., Ltd.) as an antioxidant.
1 part by weight, 0.2 parts by weight of silicone TSF433 (manufactured by Toshiba Silicone Co., Ltd.) as an antifoaming agent were added, and a theoretical amount of methanol was taken out of the system according to a conventional method while gradually raising the temperature from 150 ° C to 240 ° C. After distilling and transesterification reaction, 0.307 parts by weight of dimethyl phenylphosphonate was added, and then a slurry of silica particles having an average particle size of 1.2 μm uniformly dispersed in ethylene glycol was used as silica particles. 0.5 for condensed polyester
Part by weight was added to distill excess ethylene glycol out of the system. Then, the temperature was gradually raised from 240 ° C. and the pressure was reduced, and finally a polycondensation reaction was performed at 285 ° C. and 1 mmHg or less to obtain a polyester having an intrinsic viscosity of 0.68.

The obtained polyester was vacuum dried at 150 ° C. for 24 hours, then supplied to an extruder, melted at 285 ° C., extruded in a sheet form from a T-shaped die, and cooled and solidified.
An unstretched film was obtained. Then, the unstretched film 95
It is heated to ℃ and stretched 3.5 times in the longitudinal direction.
After heating to ℃ and stretching 3.5 times in the width direction,
It was heat-treated for 2 seconds and cooled to obtain a 1.7 μm biaxially stretched film. On one side of the film, a wax-based release agent was applied at the inlet of the stenter with a bar coater to a dry weight of 0.1 g / m ² .

The heat-sensitive stencil printing base paper was prepared by laminating the obtained film on the side not coated with a release agent with vinyl acetate as an adhesive and a natural fiber made of Manila hemp as a raw material and made of 100% natural fiber having a fiber basis weight of 10 g / m ^2. Was produced. The amount of adhesive applied was 1 g / m ² . Perforation test based on the method described above,
A printing test and evaluation of printing durability were carried out, and the results are shown in Table 1 together with the characteristics of the film.

Comparative Example 1 A heat-sensitive stencil printing base paper was obtained in the same manner as in Example 1 except that zinc acetate was used as the transesterification catalyst instead of magnesium acetate in the same weight part. A perforation test, a printing test and an evaluation of printing durability were carried out based on the above-mentioned methods, and the results are shown in Table 1 together with the properties of the obtained film.

Example 2 The amount of raw materials charged was 72.0 parts by weight of dimethyl terephthalate,
A polycondensation reaction was carried out in the same manner as in Example 1 except that 24.0 parts by weight of dimethyl isophthalate and 61.3 parts by weight of ethylene glycol were used to obtain a polyester having an intrinsic viscosity of 0.74.

Using the polyester thus obtained, a heat-sensitive stencil printing base paper was obtained in the same manner as in Example 1. A perforation test, a printing test and an evaluation of printing durability were carried out based on the above-mentioned methods, and the results are shown in Table 1 together with the properties of the obtained film.

Example 3 A stencil sheet for heat-sensitive stencil printing was obtained in the same manner as in Example 1 except that the amount of magnesium acetate added was 0.215 parts by weight.
A perforation test, a printing test and an evaluation of printing durability were carried out based on the above-mentioned methods, and the results are shown in Table 1 together with the properties of the obtained film.

Example 4 86.4 parts by weight of dimethyl terephthalate was added as a raw material.
A heat-sensitive stencil printing base paper was obtained in the same manner as in Example 1 except that dimethyl isophthalate was 9.6 parts by weight and ethylene glycol was 61.3 parts by weight. A perforation test, a printing test and an evaluation of printing durability were carried out based on the above-mentioned methods, and the results are shown in Table 1 together with the properties of the obtained film.

Example 5 Polyester of Example 1 and M / P with an intrinsic viscosity of 0.88
Polybutylene terephthalate having a ratio of 0.4 is blended in a weight ratio of 1: 1 and vacuum dried at 140 ° C. for 24 hours,
A heat-sensitive stencil printing base paper was obtained in the same manner as in Example 1 except that the temperature was stretched in the extruder and the stretching temperature in the longitudinal direction was changed to 85 ° C.
A perforation test, a printing test and an evaluation of printing durability were carried out based on the above-mentioned methods, and the results are shown in Table 1 together with the properties of the obtained film.

Comparative Example 2 A raw material was charged in an amount of 91.2 parts by weight of dimethyl terephthalate,
A base paper for heat-sensitive stencil printing was obtained in the same manner as in Example 1 except that 4.8 parts by weight of dimethyl isophthalate and 61.3 parts by weight of ethylene glycol were used. A perforation test, a printing test and an evaluation of printing durability were carried out based on the above-mentioned methods, and the results are shown in Table 1 together with the properties of the obtained film.

Example 6 A heat-sensitive stencil sheet was obtained in the same manner as in Example 1 except that the amount of magnesium acetate added was 0.038 parts by weight and the amount of dimethyl phenylphosphonate added was 0.137 parts by weight. . The punching test, the printing test and the evaluation of printing durability were carried out based on the above-mentioned methods, and the results are shown in Table 2 together with the characteristics of the film.

Example 7 Heat-sensitive stencil printing was carried out in the same manner as in Example 1 except that the unstretched film was heat-treated with a heated roll at 120 ° C. for 5 seconds before being stretched in the longitudinal direction and then stretched in the longitudinal direction at 95 ° C. I got the base paper. The punching test, the printing test and the evaluation of printing durability were carried out based on the above-mentioned methods, and the results are shown in Table 2 together with the characteristics of the film.

Example 8 A heat-sensitive stencil printing base paper was obtained in the same manner as in Example 1 except that the amount of magnesium acetate added was 0.019 parts by weight and the amount of dimethyl phenylphosphonate added was 0.044 parts by weight. . The punching test, the printing test and the evaluation of printing durability were carried out based on the above-mentioned methods, and the results are shown in Table 2 together with the characteristics of the film.

Comparative Example 3 A heat-sensitive stencil printing base paper was obtained in the same manner as in Example 1 except that the amount of magnesium acetate added was 0.150 parts by weight.
The punching test, the printing test and the evaluation of printing durability were carried out based on the above-mentioned methods, and the results are shown in Table 2 together with the characteristics of the film.

Example 9, Comparative Examples 4 and 5 A heat-sensitive stencil printing base paper was prepared in the same manner as in Example 1 except that the amount of the molten polymer supplied to the T-type die and the film-forming speed were changed, and the film thickness was changed. Got Based on the method described above, perforation test, printing test and evaluation of printing durability are carried out,
The results are shown in Table 2 together with the properties of the film.

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[Table 1]

[Table 2]

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INDUSTRIAL APPLICABILITY According to the present invention, the perforation property is good even at low energy, and the perforation diameter corresponding to the change in the energy level is provided to provide excellent gradation, and the printing durability and the curl resistance are excellent. It was possible to provide a heat-sensitive stencil printing base paper.

Claims (1)

[Claims] 1. A biaxially stretched polyester film having a thickness of 0.2 to 5 μm, the melting point of the polyester film is 240 ° C. or lower, and the amount of elemental magnesium contained in the polyester film is 10 ppm or higher,
A polyester film for heat-sensitive stencil printing base paper, which satisfies the following formula: M / P ≦ 1.0 (where M / P represents the molar ratio of magnesium element and phosphorus element contained in the polyester film).