JPH07106678B2 - Heat sensitive stencil paper - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a heat-sensitive stencil sheet, and more particularly to a heat-sensitive stencil sheet perforated by a heating element of a thermal head.

[Conventional technology]

Conventionally, as a heat-sensitive stencil sheet, there has been known one in which a thermoplastic synthetic resin film such as a polyester film is attached to a support such as a porous thin paper with an adhesive.

Examples of the adhesive include organic solvent-based adhesives, water-based adhesives, emulsion-based adhesives, hot-melt adhesives, and reactive adhesives. Among them, the working environment, the solvent resistance of the product, the moisture on the base material, and the dryness Reactive adhesives are most preferably used from the viewpoint of the effect of heat, and among these adhesives, ultraviolet curable adhesives are preferred from the viewpoints of curing speed, the effect of heat on the base material, equipment costs, etc. Most preferably used.

UV-curable adhesive is an adhesive with excellent productivity and solvent resistance. However, when a heat-sensitive stencil sheet is prepared using an adhesive that is generally commercially available, it can be used as a heat-generating element of a thermal head. Since an uncured material, a molten material, or the like is attached or deposited, the heat (energy) required for perforation is not transmitted from the heating element to the heat-sensitive stencil sheet, and there is a problem that the heat-sensitive plate making property is impaired. Further, the adhesive force between the porous support and the thermoplastic synthetic resin film was not sufficient, and it was practically difficult to use it in a plate making machine.

[Problems to be Solved by the Invention]

The object of the present invention is to solve the above-mentioned problems of the prior art and to improve the adhesive force between a porous support and a thermoplastic synthetic resin film by using an ultraviolet curable adhesive, and to generate heat from a thermal head. Another object of the present invention is to provide a heat-sensitive stencil sheet excellent in heat-sensitive plate making property in which a melted material is not attached or deposited on an element.

[Means for Solving the Problems]

As a result of intensive studies to solve the above problems, the present inventors have improved thin film curability by using an ultraviolet curable adhesive containing a polymerizable polyacrylate having two or more acryloyl groups and a specific photoinitiator. It was found that by doing so, the adhesive force between the support and the synthetic resin film was improved, and at the same time, the deposits deposited on the heating elements of the thermal head during continuous plate making were extremely reduced, and the present invention was reached.

That is, the first aspect of the present invention is a heat-sensitive stencil sheet obtained by laminating a porous support and a thermoplastic synthetic resin film with an adhesive, wherein the adhesive is a polymerizable polyacrylate having two or more acryloyl groups. An ultraviolet curable adhesive containing a photoinitiator, wherein the photoinitiator comprises:
(A) 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one, and (b) 4,
4'-bisdiethylaminobenzophenone or 4,4 '
-Bisdimethylaminobenzophenone or (c) a tertiary amine type photosensitizer, which is a heat-sensitive stencil sheet.

A second aspect of the present invention is an ultraviolet-curable adhesive, wherein the adhesive contains a polymerizable polyacrylate having two or more acryloyl groups and a photoinitiator, and the photoinitiator is
(C) A tertiary amine type photosensitizer and (d) a thioxanthone photoinitiator.

In the heat-sensitive stencil sheet of the present invention, it is preferable that the polymerizable polyacrylate having two or more acryloyl groups (hereinafter simply referred to as “polymerizable polyacrylate”) contains epoxy acrylate or urethane acrylate as a main component.

[Action]

Generally, when using a UV curable adhesive, a film,
In many cases, an adhesive is sandwiched between substrates such as glass and plastic to cure ultraviolet rays to perform adhesion, and curability, curing speed, etc. are not a problem. However, when a commercially available UV-curable adhesive is used as the heat-sensitive stencil sheet, (1) a porous material is used as the adherend, and (2) the adhesive is a thin film coating under the conditions. It is considered that UV curing and adhesion are performed, so that the adhesive is not sufficiently cured due to the influence of oxygen in the air, the adhesive strength is insufficient, and uncured components adhere to the heating element. .

In the present invention, by using a specific photoinitiator that is not affected by oxygen in the air during curing and has excellent thin film curability, the curability of the adhesive is improved and uncured components are eliminated, and the heat-sensitive element is obtained. It is possible to reduce deposits and the like on the.

Examples of the thermoplastic synthetic resin film used in the present invention include polyester film, polycarbonate film, polypropylene film, polyvinyl chloride-vinylidene chloride copolymer film and the like. The thickness of the film is preferably 10 μm or less, more preferably 1 to 6 μm. A biaxially stretched film is usually used as the film, and the stretching ratio in both the machine direction and the transverse direction is 150 to 250.
% Is preferably used.

Examples of the porous support used in the present invention include synthetic fibers such as polyester fiber, vinylon fiber and nylon fiber, and natural fibers such as Manila hemp, Kozo, Mitsumata and pulp, which may be used alone or in combination of two or more kinds. Can be used. These finenesses are preferably 3 denier or less. The basis weight is preferably 6~14g / m ^2, more preferably from 8~13g / m ^2. Furthermore, its thickness is 10-60μ
m is preferable, and more preferably 15 to 55 μm.

The UV-curable adhesive used in the present invention contains a polymerizable polyacrylate and a photoinitiator, and a reactive diluent is added if necessary.

As the polymerizable polyacrylate, for example, the following oligomers (a) to (d) are used.

(A) Polyol Polyacrylate Polyalkylene glycol, polyhydric alcohol having 2 or more valences, polyhydric alcohol such as polyhydric alcohol having alkylene oxide added to 2 or more hydration alcohol, such as polyethylene glycol diacrylate, polypropylene glycol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, trimethylolpropane triacrylate, ditrimethylolpropane tetraacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, tri- (2-acryloyloxyethyl) isocyanurate, Triacrylate of trimethylolpropane / ethylene oxide adduct, trimethylolpropane / propylene oxide Examples thereof include triacrylates of adducts.

(B) Polyester Polyacrylate Obtained by esterifying polyhydric alcohol, polyhydric carboxylic acid (anhydride) and acrylic acid, for example, diacrylate of (anhydrous) polyester diol of maleic acid and ethylene glycol, (anhydrous) Polyacrylate diol diacrylate of phthalic acid and diethylene glycol, (anhydrous) tetrahydrophthalic acid and diethylene glycol polyester diol diacrylate, adipic acid and triethylene glycol polyester diol diacrylate, (anhydrous) tetrahydrophthalic acid and triethyl phthalate Examples thereof include polyacrylates of polyester polyols with methylolpropane.

(C) Epoxy acrylate Epoxy resin having two or more epoxy groups in the molecule,
Phenol, cresol, butylphenol, octylphenol, nonylphenol and various phenol novolac resins obtained from the reaction of epichlorohydrin and epoxy resins obtained by the reaction, acrylic acid, carboxyl group-containing acrylate, acrylic acid or carboxyl group-containing acrylate and polybasic acid It can be obtained by reacting a mixture or the like, for example, bisphenol A
Diglycidyl ether diacrylate, neopentyl glycol diglycidyl ether diacrylate, 1,
Examples thereof include diacrylate of 6-hexanediol diglycidyl ether.

(D) Urethane acrylate It can be obtained by reacting a polyhydric alcohol, a polyisocyanate and a hydrogen group-containing acrylate. For example, an organic polybasic acid such as adipic acid, sebacic acid, maleic acid or terephthalic acid, and ethylene glycol or propylene. Glycol, 1,4-butylene glycol, 1,6-
Polyester diols with polyhydric alcohols such as hexanediol, tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, hydrogenated tolylene diisocyanate, isophorone diisocyanate, 1,6-
Addition reaction products of diisocyanates such as hexamethylene diisocyanate and 2-hydroxyethyl acrylate, polyether diols such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, Hydrogenated tolylene diisocyanate, isophorone diisocyanate, diisocyanate such as 1,6-hexamethylene diisocyanate,
Examples thereof include addition reaction products with 2-hydroxyethyl acrylate.

In addition to the polymerizable polyacrylate, for example, polyacryloyloxyphosphorus ester, polysiloxane polyacrylate, etc. can be used. These polymerizable polyacrylates can be used alone or as a mixture of two kinds. Of these, epoxy acrylates and urethane acrylates are preferable, and bisphenol A glycidyl ether diacrylate is particularly preferable, from the viewpoint of reducing deposits on the heating element.

As the photoinitiator, one having a small radical polymerization inhibition by oxygen in the air is used, and (a) 2-methyl-1- [4
-(Methylthio) phenyl] -2-morpholinopropan-1-one and (b) 4,4'-bisdiethylaminobenzophenone or 4,4'-bisdimethylaminobenzophenone or (c) tertiary amine type photosensitization It is used in combination with an agent or (c) a tertiary amine type photosensitizer and (ni) a thioxanthone photoinitiator. Other photoinitiators may be used in combination with these photoinitiators, such as (a) and (b) with (c) other photoinitiators, or (c) and (d). )
(A) Other photoinitiators can be used in combination.

Examples of the tertiary amine type photosensitizer (c) include methyl p-dimethylaminobenzoate, ethyl p-dimethylaminobenzoate, isoamyl p-dimethylaminobenzoate, 2-dimethylaminoethylbenzoate, and 2-butoxyethyl. -4-Dimethylaminobenzoate or the like is used, and as the thioxanthone photoinitiator (d), 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4
-Diethylthioxanthone, 2,4-diisopropylthioxanthone and the like are used.

The addition amount of the photoinitiator is based on the total amount of the polymerizable polyacrylate and the reactive diluent used as necessary,
It is preferably in the range of 1 to 10% by weight, more preferably 2 to 6
% By weight.

Reactive diluents used as necessary include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-methoxyethyl acrylate, ethyl carbitol acrylate, butoxyethyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, benzyl acrylate. , Phenoxyethyl acrylate, phenoxydiethylene glycol acrylate, nonylphenoxydiethylene glycol acrylate, tetrahydrofurfuryl acrylate, caprolactone-modified tetrahydrofurfuryl acrylate, acrylic monomers such as 2-hydroxy-3-phenoxypropyl acrylate, and N-vinylpyrrolidone. These can be used alone or in combination of two or more. These diluents are used, for example, when the viscosity of the adhesive is high.

A leveling agent, a coloring agent, a deodorant and the like can be added to the ultraviolet curable adhesive used in the present invention within a range not impairing its performance.

The heat-sensitive stencil sheet of the present invention, the surface of the thermoplastic synthetic resin film, the ultraviolet curing adhesive is applied, the porous support on it, for example, pressure-bonded at a pressure of ² kg / m ² or more. After that, the UV irradiation lamp with an output of 40 W / cm
It can be obtained by irradiation for 0.04 seconds / cm or more.

〔Example〕

 Hereinafter, the present invention will be described in detail with reference to Examples.

Example 1 A surface of a polyester film having a thickness of 2 μm was coated with a roll coater at a coating amount of 0.8 g / m ² of an ultraviolet-curable adhesive No. 1 having the composition and blending amount shown in Table 1, and then a porous layer was formed. Polyester paper having a basis weight of 12 g / m ² was pressure-bonded as the permeable support. Immediately thereafter, ultraviolet rays were irradiated by an ultraviolet irradiation device (manufactured by Nippon Battery Co., Ltd., High Cure System DHC-40K-3DB, output 40 W / cm) to cure the adhesive and bond the film and the support. The running speed at this time was 10 m / min. Next, 0.2 g of a release agent made of silicone resin on the film side of this base paper
A roll coater was applied at an application amount of / m ² to obtain a heat-sensitive stencil sheet.

The obtained heat-sensitive stencil sheet was subjected to plate-making printing using a digital plate-making printing machine (Iso Kagaku Kogyo KK, Lithograph 007D III N). Regarding the contamination state of the thermal head, printing was repeated up to 150 plates by continuous plate making of the solid part, and the change in the surface state of the heating element and the change in the print density before and after the printing were observed.

The evaluation of the cured state was carried out by immersing the heat-sensitive stencil sheet in ethyl acetate, toluene and methanol at 25 ° C. for 30 minutes, and observing the peeled state of the film and the support.

Further, the heat-sensitive stencil sheet was cut into 2 cm × 10 cm test pieces, and the peel strength between the film and the support was measured under the conditions of a peeling angle of 180 ° C. and a peeling speed of 10 cm / min. The results are shown in Table 2.

Examples 2 to 5 Example 1 except that the ultraviolet curable adhesives Nos. 2 to 5 having the compositions and amounts shown in Table 1 were used.
A heat-sensitive stencil sheet was prepared and evaluated in the same manner as in. The results are shown in Table 2.

Polymerizable polyacrylate A: Bisphenol A diglycidiether diacrylate B: Urethane acrylate Reactive diluent C: 2-Hydroxy-3-phenoxypropyl acrylate D: N-Vinylpyrrolidone E: Tetrahydrofurfuryl acrylate Photoinitiator F: Benzyl Dimethyl ketal G: 2-methyl-1- [4- (methylthio) phenyl]-
2-morpholinopropan-1-one H: 4,4'-bisdimethylaminobenzophenone I: p-dimethylaminoisoamyl benzoate J: 2,4-diethylthioxanthone Comparative Example 1 A heat-sensitive stencil sheet was prepared and evaluated in the same manner as in Example 1 except that the ultraviolet curable adhesive No. 6 having the composition and blending amount shown in Table 1 was used. The results are shown in Table 1, but deposits were formed on the surface of the TPH element, and the peel strength was poor.

Comparative Example 2 A heat-sensitive stencil sheet was prepared and evaluated in the same manner as in Example 1 except that the ultraviolet curable adhesive No. 7 having the composition and blending amount shown in Table 1 was used. The results are shown in Table 1, and many deposits were generated on the surface of the TPH element.

〔The invention's effect〕

According to the heat-sensitive stencil sheet of the present invention, the following excellent effects can be obtained.

(1) Since a stable heat-sensitive plate-making property is obtained in which a melted material or the like of the heat-sensitive stencil sheet is not attached to or deposited on the heating element of the thermal head, a clear printed matter can be obtained. Further, the work of cleaning the thermal head is not required, and the workability is excellent.

(2) Since no solvent is used in the step of laminating the heat-sensitive stencil sheet, there is no problem in working environment.

(3) It is excellent in productivity because it is instantly cured by being irradiated with ultraviolet rays.

(4) The resin has a high crosslink density and the product has excellent solvent resistance.

(5) Since the resin viscosity before curing can be set low, stable production can be achieved with a low coating amount.

(6) The adhesive strength is improved.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tetsuji Minematsu 1-1 Funami-cho, Minato-ku, Nagoya-shi, Aichi Toagosei Chemical Industry Co., Ltd. (72) Inventor Hideki Matsubara 1 Funami-cho, Minato-ku, Nagoya-shi, Aichi 1-chome, Toagosei Chemical Industry Co., Ltd. (56) Reference JP-A-154796 (JP, A)

Claims (3)

[Claims] 1. A heat-sensitive stencil sheet prepared by laminating a porous support and a thermoplastic synthetic resin film with an adhesive,
The adhesive is a UV-curable adhesive containing a polymerizable polyacrylate having two or more acryloyl groups and a photoinitiator, wherein the photoinitiator is (a) 2-methyl-
1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one and (b) 4,4'-bisdiethylaminobenzophenone or 4,4'-bisdimethylaminobenzophenone or (c) tertiary amine A heat-sensitive stencil sheet containing a photosensitizer. 2. A heat-sensitive stencil sheet prepared by laminating a porous support and a thermoplastic synthetic resin film with an adhesive,
The adhesive is an ultraviolet curable adhesive containing a polymerizable polyacrylate having two or more acryloyl groups and a photoinitiator, wherein the photoinitiator is (c) a tertiary amine type photosensitizer. A heat-sensitive stencil sheet comprising an agent and a (d) thioxanthone photoinitiator. 3. The heat-sensitive stencil sheet according to claim 1, wherein the polymerizable polyacrylate having two or more acryloyl groups contains epoxy acrylate or urethane acrylate as a main component.