JPH10272688A - Film for thermal stencil printing raw paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film which has high sensitivity and is suitable for thermal stencil printing raw paper with little curl. SOLUTION: The film for thermal stencil printing raw paper consists of a blend body which is obtained by at least mixing resin B being polyester-based resin with resin A being the same. Crystallization temperature of resin B is higher than crystallization temperature of resin A by >=3 deg.C. Also, the number average molecular weight of resin B is smaller than the number average molecular weight of resin A by <=90%. Resin B is contained in a range within 0.1-35 wt.%. The film is stretched at least in the uniaxial direction. Thermal shrinkage factor at 100 deg.C is a range within 3-45% respectively lengthwise and crosswise.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a thermal head,
The present invention relates to a heat-sensitive stencil film for a stencil sheet which is perforated by various kinds of heat such as flash and laser.

[0002]

2. Description of the Related Art Hitherto, a film made of a polyester resin has been widely used as a base material for base paper for heat-sensitive stencil printing. For example, a heat-sensitive stencil sheet using a stencil film for stencil printing, as disclosed in JP-A-3-39294 and JP-B-6-45271, is known.

[0003]

However, the stencil film and the heat-sensitive stencil sheet using the stencil film proposed above are excellent in perforation sensitivity by heat such as a thermal head, a flash, and a laser. However, there is a problem of curling of the base paper which occurs at room temperature or slightly higher than room temperature due to high heat shrinkage at low temperature. In such heat-sensitive stencil printing paper, there is a concern that it is difficult to run, and there is a concern that contact with a printing medium may be uneven, so that practical problems remain.

An object of the present invention is to provide a film for a heat-sensitive stencil sheet which has high sensitivity and little curl, paying attention to such a remaining problem.

[0005]

Means for Solving the Problems In order to solve the above-mentioned problems, a film for heat-sensitive stencil printing paper of the present invention comprises a blend obtained by mixing at least a resin A and a resin B which are polyester resins. The crystallization temperature of B is resin A
Is higher than the crystallization temperature of the resin A by 3 ° C. or more, and the number average molecular weight of the resin B is 90% or less of that of the resin A;
Is contained in the range of 0.1% by weight to 35% by weight, and is a film stretched in at least one axis direction,
The heat shrinkage at 100 ° C. is in the range of 3% to 45% each in the vertical and horizontal directions.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The polyester resin of the present invention is a crystalline thermoplastic resin compound polymerized by an ester bond.
Such a polyester is obtained by polycondensing a dicarboxylic acid component and a glycol component. As the dicarboxylic acid component, terephthalic acid, isophthalic acid, aromatic dicarboxylic acids such as naphthalenedicarboxylic acid, adipic acid, sebacic acid, dodecadionic acid, aliphatic dicarboxylic acids such as azelaic acid, and alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid Acids and the like can be used,
As the glycol component, an aliphatic diol such as ethylene glycol, diethylene glycol, butanediol, and hexanediol can be used.

The blend of the polyester resin of the present invention is obtained by mixing a resin A and a resin B in which at least one selected from the above dicarboxylic acid components and glycol components is combined. In addition, within the scope of the present invention, a polyester resin other than the resin A and the resin B may be mixed. The intrinsic viscosity of the polyester resin of the present invention is practically and preferably in the range of 0.3 to 1.9.

Further, the polyester resin of the present invention includes:
Inorganic and / or organic particles may be added. Examples of the shape of the particles to be added include a true sphere, an agglomerate, a scale, and a bead. Further, the polyester resin of the present invention includes, for example, thermoplastic resins such as various nylons, polyethylene, polypropylene, polystyrene, 4-methylpentene, polyvinyl alcohol, and silicone resins, and fluororesins to the extent that the physical properties of the film are not impaired. , A non-thermoplastic resin such as an imide resin, and various modified resins such as ethylene-vinyl acetate and an ionomer.

The resin B of the present invention needs to have a crystallization temperature higher than that of the resin A by 3 ° C. or more. That is, if the crystallization temperature of the resin B is not higher than the resin A by 3 ° C. or more, sufficient curling resistance is not exhibited. Preferably, the temperature is 5 ° C. or higher, more preferably 10 ° C. or higher.

The resin B of the present invention must have a number average molecular weight of 90% or less based on the resin A. That is, if the number average molecular weight of the resin B is more than 90% with respect to the resin A, even if the above-mentioned crystallization temperature is satisfied, sufficient curling resistance cannot be obtained. Preferably 80
%, More preferably 70% or less.

[0011] The resin B of the present invention must be contained in an amount of 0.1 to 35% by weight. That is, if the content is less than 0.1% by weight, satisfactory curling resistance cannot be obtained, while if it is more than 35% by weight, film breakage or the like occurs frequently during film formation. Not stable. Preferably 0.1 to 25% by weight, more preferably 0.1 to 5% by weight
Is the content of

The heat-sensitive stencil film of the present invention is
It must be stretched in at least one axial direction. That is, when the film is not stretched in at least one axial direction, perforation by heat becomes insufficient, resulting in insufficient sensitivity.

The film for heat-sensitive stencil printing base paper of the present invention 1
The heat shrinkage at 00 ° C. needs to be in the range of 3-45%. That is, when the heat shrinkage is less than 3%, the perforation by heat is insufficient and the sensitivity becomes insufficient. On the other hand, when the heat shrinkage is more than 45%, the curl of the film becomes large. Preferably 8 to 35%, more preferably 10%
２５25%.

The film 6 for the heat-sensitive stencil sheet of the present invention
The heat shrinkage at 5 ° C. is preferably less than 0.5%. That is, when it is 0.5% or more, the curl of the film becomes large. More preferably less than 0.3%, even more preferably less than 0.2%.

[0015] In the heat-sensitive stencil printing sheet film of the present invention, the longitudinal direction of the heat shrinkage factor S _MD at 100 ° C., the thermal shrinkage factor S _TD in the transverse _{direction, S TD -15 ≦ S MD ≦} S TD (% It is preferable to satisfy the relationship of (1). That is, S _TD- 15> S
If the _MD is for the insufficient sensitivity not obtained it becomes sufficient perforation, whereas in the case of S _MD> S _TD are not independent opening portion opening becomes too large due to drilling, high This is because density printing becomes difficult. More preferably, S _TD -10 ≦ S
That is, the relationship of _MD ≦ _STD (%) is satisfied.

In the film for heat-sensitive stencil printing paper of the present invention, the melting peak is preferably substantially one peak. That is, when there are two or more melting peaks, sharp perforation becomes difficult, resulting in insufficient sensitivity.

Further, the film for heat-sensitive stencil printing paper of the present invention preferably has a pseudo-crystal melting peak, and the pseudo-crystal melting peak is in the range of the glass transition temperature Tg or lower. Here, the pseudo-crystal melting peak refers to a peak that appears in the form of a shoulder of a Tg peak near Tg.

In the heat-sensitive stencil film of the present invention, digital perforation with a thermal head of 600 DPI or more is preferable because it meets the purpose of high sensitivity.

Further, it is preferable that the shape of the heat generating portion of the thermal head used for printing the film for heat-sensitive stencil printing base paper of the present invention is such that the length in the direction parallel to the base paper traveling direction is larger than the length in the vertical direction. . That is, if the thermal head is vertically long, it is possible to arrange many heat generating portions in the width direction, and as a result, high-density printing can be performed.

Next, a method for producing the film for heat-sensitive stencil printing paper of the present invention will be described, but the method is not necessarily limited thereto.

First, a dicarboxylic acid component and a glycol component are polymerized. In this case, a known method can be used for the method and the adjustment of the number average molecular weight.

Thereafter, a predetermined additive was added to the polyester resin dried to a water content of 150 ppm or less,
The mixture is melted, kneaded, extruded into a sheet at 00 to 350 ° C. by a conventional extruder, and quenched on a drum. 75-1
It is stretched 2.5 to 8 times in the machine direction at 35 ° C.,
It is stretched 2.5 to 6 times in the transverse direction at ~ 150 ° C. Thereafter, a heat treatment is performed at 180 to 255 ° C, and a relaxation treatment of 0 to 10% is performed. The stretching order may be reversed if necessary. If necessary, an aqueous coating may be applied to the sheet or film. In this case, an aqueous coating is applied to the uniaxially stretched film, and after drying or while drying, the first coating is applied under the conditions described above. The film is stretched in a direction perpendicular to the above. Finally, the product is cut into a predetermined width.

[Evaluation method of physical property values] (1) Measurement of heat shrinkage values The values at 65 ° C and 100 ° C were measured according to JIS-C2318.

(2) Crystallization temperature After holding at 280 ° C for 10 minutes using a differential scanning calorimeter, the temperature was lowered at 20 ° C / minute, and the crystallization peak temperature was defined as the crystallization temperature.

(3) Melting peak Using a differential scanning calorimeter, the resin is held at 280 ° C. for 10 minutes, and then cooled at a rate of 20 ° C./minute to 10 ° C. When the sample was heated at a rate of 10 ° C./min, a crystal melting peak detected was measured.

(4) Using a differential scanning calorimeter, the pseudocrystal melting peak sample was first heated at a rate of 10 ° C./min, then at a temperature higher than the glass transition temperature Tg, and then at a rate of 10 ° C./min. Cooling. Thereafter, when the temperature was raised again at 10 ° C./min, a peak which was present at the first temperature increase and disappeared or changed due to the subsequent temperature decrease was determined as a pseudo-crystal melting peak temperature.

(5) Base paper curl At 20 ° C. and 45% RH atmosphere, a gauze and a film having a basis weight of 30 g / m ² are adhered together to obtain a stencil printing base paper. This is 3
40 ° C, 70% RH as a 0cm square sample
Leave in the atmosphere for 5 hours. The curl of the left sample is 1
When the angle was 80 degrees or more, it was judged as x, and when it was smaller than 80 degrees, it was judged as o.

(6) Perforation Sensitivity The heat-sensitive stencil sheet obtained in (5) above has a heat-generating part size of 5 μm in the film flow direction and 20 μm in the width direction.
Using a stencil printing machine equipped with a DPI thermal head, a solid black screen was read and perforated. The perforated thermosensitive stencil sheet was magnified and observed for the shape of the perforated portion, and judged according to the following criteria. · ：: When each perforated portion is independent of each other and the opening area is 300% or more in terms of the area ratio of the heat generating portion. · ○: Each perforated portion is independent of each other and the open area is 150 in terms of the area ratio of the heat generating portion. % Or more, ×: In cases other than the above.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments. Example 1 As the carboxylic acid component, terephthalic acid and isophthalic acid were polymerized at a ratio of 90:10 mol%, and the glycol component was polymerized with ethylene glycol at 100 mol% to obtain resin A pellets having a number average molecular weight of 19,500. Was. On the other hand, terephthalic acid is used as a carboxylic acid component.
0 mol%, ethylene glycol is used as the glycol component and polymerization is performed with 100 mol%, and the number average molecular weight is 1
A resin B pellet of 3,000 was obtained.

95% by weight of resin A pellets and 5% by weight of resin B pellets are mixed, dried so that the water content in each resin pellet becomes 25 ppm, melted at 280 ° C., and extruded from a die into a sheet. Quenched with a cooling drum. The sheet was stretched 5.8 times in the machine direction at 80 ° C, and then stretched 4.5 times in the transverse direction at 110 ° C. Subsequently, heat treatment was performed at 120 ° C. to obtain a biaxially stretched film. When the film thus obtained was used as a heat-sensitive stencil sheet, the perforation sensitivity was good and the curl was good with little curl.

Example 2 In Example 1, the resin B was polymerized by using terephthalic acid as a carboxylic acid component at 100 mol% and butanediol as a glycol component at 100 mol% to obtain a number-average molecular weight of 13,500. 4.5
A film was obtained in the same manner as in Example 1 except that the film was stretched 4.9 times in the transverse direction instead of stretching twice. When the film thus obtained was used as a heat-sensitive stencil sheet, the perforation sensitivity was good, and the curl was extremely small and good.

Example 3 In Example 2, 110 ° C. was used instead of the heat treatment at 120 ° C.
A film was obtained in the same manner as in Example 2 except that the heat treatment was performed. When the obtained film was used as a heat-sensitive stencil sheet, the perforation sensitivity was good, and the curl was good with little curl.

Example 4 In Example 3, 85: 15% by weight of resin A and resin B were used.
The film was obtained in the same manner as in Example 3 except that the films were mixed at a ratio of 1. As in Example 3, the perforation sensitivity was good,
A good heat-sensitive stencil sheet with little curl was obtained.

Comparative Example 1 The procedure of Example 1 was repeated except that the resin B was polymerized with terephthalic acid as the carboxylic acid component at 100 mol% and butane diol at 100 mol% as the glycol component to make the number average molecular weight 19,500. A film was obtained in the same manner as in Example 1. When the film thus obtained was used as a heat-sensitive stencil sheet, a large curl result was obtained.

Comparative Example 2 In Example 1, the number average molecular weight of the resin B was 24,000
A film was obtained in the same manner as in Example 1 except that the film was set to 0. When the film thus obtained was used as a heat-sensitive stencil sheet, a large curl result was obtained.

Comparative Example 3 A film was obtained in the same manner as in Example 1 except that only resin A was used without mixing resin B.
When the film thus obtained was used as a heat-sensitive stencil sheet, a large curl result was obtained.

Comparative Example 4 In Example 3, 50: 50% by weight of resin A and resin B were used.
The same method as in Example 3 was used except that the mixture was carried out at a ratio of 1. However, the film formation was not stabilized and a film could not be obtained.

Comparative Example 5 In Example 1, terephthalic acid and isophthalic acid were used as the carboxylic acid component in a ratio of 90:10 mol% as the resin B, and butanediol was used as the glycol component.
Polymerized as 0 mol% and the number average molecular weight was 22,000.
Using only resin B without mixing resin A,
A film was obtained in the same manner as in Example 1 except that no heat treatment was performed after the completion of stretching. When the film thus obtained was used as a heat-sensitive stencil sheet, a large curl result was obtained.

Comparative Example 6 In Comparative Example 3, 190 ° C. was used instead of the heat treatment at 120 ° C.
A film was obtained in the same manner as in Comparative Example 3 except that the heat treatment was performed. When the film thus obtained was used as a heat-sensitive stencil sheet, poor perforation sensitivity was obtained.

[0040]

[Table 1]

[0041]

According to the present invention, high sensitivity and
A film suitable for heat-sensitive stencil printing paper with less curl can be provided.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI B29L 7:00

Claims (6)

[Claims] 1. A blend comprising at least a resin A and a resin B, which are polyester-based resins, wherein the crystallization temperature of the resin B is higher than the crystallization temperature of the resin A by 3 ° C. or more; Has a number average molecular weight of 90 of that of resin A.
% Or less, and the resin B is contained in the range of 0.1% by weight to 35% by weight, and is a film stretched in at least one axis direction, and has a heat shrinkage at 100 ° C. A film for heat-sensitive stencil printing paper, wherein each width is in the range of 3% to 45%. 2. A longitudinal direction of the heat shrinkage factor S _MD at 100 ° C., the thermal shrinkage factor S _TD in the transverse direction and satisfying the relation of _{S TD -15 ≦ S MD ≦ S} TD (%), The film for heat-sensitive stencil printing paper according to claim 1. 3. The resin B is contained in a range of 0.1% by weight to 5% by weight, has a heat shrinkage at 65 ° C. of 0.5% or less, and is digitally punched by a thermal head of 600 DPI or more. The film for heat-sensitive stencil printing base paper according to claim 1 or 2, characterized in that: 4. The heat generating section according to claim 1, wherein the shape of the heat generating portion is perforated by a thermal head having a length in a direction parallel to the base paper advancing direction larger than a length in a vertical direction. The film for heat-sensitive stencil printing paper according to the above. 5. The film for heat-sensitive stencil printing paper according to claim 1, wherein the melting peak is substantially one peak. 6. The film for heat-sensitive stencil printing paper according to claim 1, which has a pseudo-crystal melting peak in a range of a glass transition temperature Tg or less.