JPH0281691A - Thermal stencil paper - Google Patents

Abstract

PURPOSE:To lessen an adhering deposit on a heating element of a thermal head by improving adhesion between a base material and a synthetic resin film by a method wherein a thin film curing property is improved by using an ultraviolet curing adhesive which contains a polymerizable polyacrylate having two or more acryloyl radicals and a specific photoinitiator. CONSTITUTION:An adhesive is an ultraviolet curing adhesive which contains a polymerizable polyacrylate having two or more acryloyl radicals and a photoinitiator. The photoinitiator contains (A) 2-methyl-1-[4-(methylthio)phenyl]-2- morpholinopropane-1-one and (B) 4,4'-bisdiethylaminobenzophenone, or 4,4'- bisdimethylaminobenzenephenone, and otherwise (C) tertiary amine type photosensitizer. By using a specific photoinitiator which receives no influence of oxygen when cured and is excellent in a thin film curing property, the curing property of the adhesive is improved to remove a non-cured component, and a deposit to a thermal element can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a heat-sensitive stencil paper, and more particularly to a heat-sensitive stencil paper perforated by a heating element of a thermal head.

[Prior art]

Conventionally, as a heat-sensitive stencil paper, one in which a thermoplastic synthetic resin film such as a polyester film is laminated with an adhesive on a support such as a porous tissue paper is known.

These adhesives include organic solvent-based water-based adhesives, emulsion-based adhesives, hot-melt adhesives, and reactive adhesives, but among these adhesives are the working environment, the product's solvent resistance, moisture and dryness of the base material, etc. Reactive adhesives are most preferably used in terms of the effect of heat on the substrate, and among these reactive adhesives, ultraviolet curing adhesives are preferred in terms of curing speed, heat effect on the base material, equipment cost, etc. agents are most preferably used.

Ultraviolet curing adhesives are adhesives with excellent productivity and solvent resistance. However, when heat-sensitive stencil paper is made using commercially available adhesives, adhesives, etc. may be applied to the heating elements of the thermal head. Since uncured materials, molten materials, etc. adhere or accumulate, the heat (energy) necessary for perforation is not transmitted from the heat generating element to the thermal stencil paper, resulting in a problem of impairing thermal stencil making properties. Furthermore, the adhesion between the porous support and the thermoplastic synthetic resin film was insufficient, making it difficult to use in a plate-making machine in practice.

[Problem to be solved by the invention]

An object of the present invention is to solve the problems of the prior art described above, to improve the adhesive force between a porous support and a thermoplastic synthetic resin film using an ultraviolet curable adhesive, and to improve the adhesive strength of a thermal head. It is an object of the present invention to provide a heat-sensitive stencil paper which is convenient in heat-sensitive stencil making without adhesion or accumulation of molten matter on elements.

[Means to solve the problem]

As a result of intensive research to solve the above problems, the present inventors improved thin film curability by using a polymerizable polyacrylate having two or more acryloyl groups and an ultraviolet curable adhesive containing a specific photoinitiator. The present inventors have discovered that by doing so, the adhesive force between the support and the synthetic resin film is improved, and at the same time, the amount of deposits adhering to the heating element of the thermal head that occurs during continuous plate making is extremely reduced, and the present invention has been achieved.

That is, the first aspect of the present invention is a heat-sensitive stencil paper formed by bonding a porous support and a thermoplastic synthetic resin film with an adhesive, in which the adhesive is a polymerizable polyacrylate having two or more acryloyl groups. An ultraviolet curable adhesive containing a photoinitiator, wherein the photoinitiator is (a) 2-methyl-1-(4-(methylthio)phenyl]-
2-morpholinopropan-1-one and (b)4.4'
-bisdiethylaminobenzophenone or 4゜4I
- bisdimethylaminobenzophenone, or (iii) a tertiary amine type photosensitizer.

A second aspect of the present invention is an ultraviolet curable adhesive comprising a polymerizable polyacrylate having two or more acryloyl groups and a photoinitiator, wherein the photoinitiator is (
c) It is characterized by containing a tertiary amine type photosensitizer and (d) a thioxanthone type photoinitiator.

In the heat-sensitive stencil paper of the present invention, the polymerizable polyacrylate having two or more acryloyl groups (hereinafter simply referred to as "polymerizable polyacrylate") preferably contains epoxy acrylate or urethane acrylate as a main component.

[Effect]

Generally, when using UV-curable adhesives, film,
Adhesion is often achieved by sandwiching an adhesive between base materials such as glass or plastic and curing it with ultraviolet light, and curability, curing speed, etc. are rarely a problem. However, when a commercially available ultraviolet curing adhesive is used on heat-sensitive stencil paper, the following conditions apply: (1) a porous material is used as the adherend, and (2) the adhesive is coated in a thin film. Since UV curing and adhesion are performed, the adhesive is not sufficiently cured due to the influence of oxygen in the air, resulting in insufficient adhesive strength, and it is thought that uncured components may adhere to the heat-sensitive element. .

In the present invention, by using a specific photoinitiator that is not affected by oxygen in the air and has excellent thin film curing properties during curing, the curing properties of the adhesive are improved and uncured components are eliminated. It is possible to reduce the amount of substances adhering to the surface.

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 108 m or less, more preferably 1 to 6 μm. In addition, the film is usually a biaxially stretched film, and has a stretching ratio of 150 to 150 in both the longitudinal and transverse directions.
250% is preferably used.

Examples of the porous support used in the present invention include synthetic fibers such as polyester fibers, vinylon fibers, and nylon fibers, and natural fibers such as Manila hemp, mulberry, mitsumata, and bulb, which may be used alone or in combination of two or more. It can be used as The fineness of these materials is preferably 3 deniers or less. Moreover, the basis weight is preferably 6 to 14 g/rtT, more preferably 8 to 13 g/rdT. Further, the thickness thereof is preferably 10 to 6011 m, more preferably 15 to 55 m.

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

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

(a) Polyol polyacrylate polyacrylate such as polyalkylene glycol, polyhydric alcohol with a valence of 2 or more, polyhydric alcohol with an alkylene oxide added to a polyhydric alcohol with a valence of 2 or more,
For example, polyethylene glycol diacrylate, polypropylene glycol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, trimethylolpropane triacrylate, ditrimethylolpropane tetraacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, Examples include tri(2-acryloyloxyethyl)isocyanurate, triacrylate of trimethylolpropane/ethylene oxide adduct, and triacrylate of trimethylolpropane/propylene oxide adduct.

(b) Polyester polyacrylate Obtained by esterifying polyhydric alcohol, polyhydric carboxylic acid (anhydride) and acrylic acid, for example (
(anhydrous) diacrylate of polyester diol with maleic acid and ethylene glycol, (anhydride) diacrylate of polyester diol with phthalic acid and diethylene glycol, (anhydride) diacrylate of polyester diol with tetrahydrophthalic acid and diethylene glycol,
Examples include diacrylates of polyester diols of adipic acid and triethylene glycol, and polyacrylates of polyester polyols of (anhydrous) tetrahydrophthalic acid and trimethylolpropane.

(C) an epoxy resin having two or more epoxy groups in the epoxy acrylate molecule;
Acrylic acid, carboxyl group-containing acrylates, acrylic acid or carboxyl group-containing acrylates, and polybasic acids are added to epoxy resins obtained from the reaction of various phenol novolac resins obtained from phenol, cresol, butylphenol, octylphenol, nonylphenol, etc., and epichlorohydrin. For example, diacrylate of bisphenol A diglycidyl ether, diacrylate of neopentyl glycol diglycidyl ether,
Examples include diacrylate of 1,6-hexanesiol diglycidyl ether.

(d) Urethane acrylate Can be obtained by reacting polyhydric alcohol, polyvalent isocyanate, and hydrogen group-containing acrylate, for example, with organic polybasic acids such as adipic acid, sebacic acid, maleic acid, and terephthalic acid, and ethylene glycol, propylene Glycol, 1゜4-butylene glycol, l,
polyester diol with polyhydric alcohols such as 6-hexanediol, and tolylene diisocyanate), 4.4
"Diphenylmethane diisocyanate, hydrogenated tolylene diisocyanate, isophorone diisocyanate, 1
．． Addition reaction product of diisocyanate such as 6-hexamethylene diisocyanate and 2-hydroxyethyl acrylate, polyether diol such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and tolylene diisocyanate, 4,41
-diphenylmethane diisocyanate, hydrogenated tolylene diisocyanate, isophorone diisocyanate, 1
．． Examples include addition reaction products of diisocyanates such as 6-hexamethylene diisocyanate and 2-hydroxyethyl acrylate.

In addition to the polymerizable polyacrylate, for example, polyacryloyloxyphosphate, polysiloxane polyacrylate, etc. can also be used. These polymerizable polyacrylates can be used alone or in combination. Among these, epoxy acrylate and urethane acrylate are preferred from the viewpoint of reducing deposits on the heating element, and among these, bisphenol A glycidyl ether diacrylate is particularly preferred.

The photoinitiator used is one that is less inhibited by radical polymerization by oxygen in the air, and (a) 2-methyl-1-(4
-(methylthio)phenyl2-morpholinopropan-1-one and (b) 4゜4'-bisdiethylaminobenzophenone or 4,4g-bisdimethylaminobenzophenone or (c) a tertiary amine type photosensitizer. or (c) a tertiary amine type photosensitizer and (d) a thioxanthone type photoinitiator. Other photoinitiators may be used in combination with these photoinitiators, for example, (a) and (b).
(c) Other photoinitiators can be used together, or (c) and (d) can be used together with (a) other photoinitiators.

Examples of the tertiary amine photosensitizer (c) include methyl p-dimethylaminobenzoate, ethyl p-dimethylaminobenzoate, isoamyl p-dimethylaminobenzoate, 2-
Dimethylaminoethylbenzoate, 2-butoxyethyl-4-dimethylaminobenzoate, etc. are used,
Further, as the thioxanthone photoinitiator (d), 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, etc. are used.

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

Reactive diluents used as necessary include 2-hydroxylethyl acrylate, 2-hydroxypropyl acrylate, 2-methoxyethyl acrylate, ethylcarpitol acrylate, butoxyethyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, Benzyl acrylate, phenoxyethyl acrylate, phenoxydiethylene glycol acrylate, nonylphenoxydiethylene glycol acrylate, tetrahydrofurfuryl acrylate,
Examples include acrylic monomers such as caprolactone-modified tetrahydrofurfuryl acrylate and 2-hydroxy-3-phenoxypropyl acrylate, N-vinylpyrrolidone, and the like, and these can be used alone or in combination of two or more. These diluents are used, for example, when the adhesive has a high viscosity.

A leveling agent, a coloring agent, a deodorizing agent, etc. can be added to the ultraviolet curable adhesive used in the present invention within a range that does not impair its performance.

The heat-sensitive stencil paper of the present invention is produced by coating the surface of the thermoplastic synthetic resin film with the ultraviolet curable adhesive and pressing the porous support thereon with a pressure of, for example, 2 kg/rrf or more. , by irradiating ultraviolet rays for 0.04 seconds/C11 or more using an ultraviolet irradiation lamp with an output of 40 W/1.

〔Example〕

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

Example 1 After coating the surface of a 2 μm thick polyester film with an ultraviolet curable adhesive Nα1 having the composition and blending amount shown in Table 1 at a coating amount of 0.8 g/po using a roll coater, a porous support was applied. A polyester paper having a basis weight of 12 g/% was press-bonded as a body. Immediately after that, use an ultraviolet irradiation device (made by Nippon Battery Co., Ltd.,
High Cure System DHC-40 - 3DB, output 40
The adhesive was cured by irradiation with ultraviolet rays (W/cm), and the film and support were bonded together. The running speed at this time is 10
m/l1lIn. Next, a release agent made of silicone resin was applied to the film surface of the base paper using a roll coater in an amount of 0.2 g/nf to obtain a heat-sensitive stencil paper.

The obtained heat-sensitive stencil paper was subjected to plate-making printing using a digital plate-making printing machine (Risograph 007DHIN, manufactured by Riso Kagaku Kogyo Co., Ltd.). The contamination state of the thermal head was determined by repeating printing up to 150 plates by continuous plate making of the solid area, and observing changes in the surface condition of the heat generating element before and after that, and observing changes in the print density of the printed matter.

The curing state was evaluated by immersing the heat-sensitive stencil paper in ethyl acetate, toluene, and methanol for 30 minutes at 25°C, and observing the state of peeling between the film and the support.

Also, cut the heat-sensitive stencil paper into 2cm x 10cm test pieces.
The peel strength between the film and the support was measured at a peel angle of 180°C and a peel rate of 10 cm/min.

The results are shown in Table 2.

Examples 2 to 5 Heat-sensitive stencil paper was prepared and evaluated in the same manner as in Example 1, except that ultraviolet curable adhesives Nα2 to 5 having the composition and blending amount shown in Table 1 were used in Example 1. did. The results are shown in Table 2.

Table 1 Polymerizable polyacrylate A: Bisphenol A diglycidyl ether diacrylate B: Urethane acrylate Reactive diluent C: 2-hydroxy-3-phenoxypropylacrylate D: N-vinylpyrrolidone E: Tetrahydrofurfuryl acrylate Photoinitiator F: Benzyldimethylkecure G: 2-methyl-1-(4-(methylthio)phenyl-2-mol propan-1-one H: 4.4'-bisdimethylaminobenzophenone ta
Isoamyl p-dimethylaminobenzoate J: 2,4-diethylthioxanthone ml O: The surfaces of the T, P, and H elements were very clean, there were no deposits, and clear images were obtained that did not affect the printed matter. .

Δ: There was no abnormality in the printed matter, but there were deposits on the surfaces of the T, P, and H elements.

X: There were many deposits on the surfaces of the T, P, and H elements, and some portions of the printed matter were not printed.

*20: No peeling due to immersion in solvent.

Umbrella 3 The peel strength of adhesive Nα6 was expressed as a converted value of 1.

Table 2 Comparative Example 1 A heat-sensitive stencil paper was prepared and evaluated in the same manner as in Example 1, except that the ultraviolet curable adhesive Nα6 having the composition and amount shown in Table 1 was used. The results are shown in Table 1, and T.

Deposits were formed on the surfaces of the P and H elements, and the peel strength was poor.

Comparative Example 2 A heat-sensitive stencil paper was prepared and evaluated in the same manner as in Example 1, except that the ultraviolet curable adhesive Nα7 having the composition and content shown in Table 1 was used. The results are shown in Table 1, and T.

Many deposits were generated on the surfaces of the P and H elements.

〔Effect of the invention〕

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

(1) Stable heat-sensitive stencil-making properties are obtained, with no adhesion of molten material of the heat-sensitive stencil paper to the heating element of the thermal head, and no deposits, so that clear printed matter can be obtained. Furthermore, there is no need to clean the thermal head, resulting in excellent workability.

(2) No solvent is used in the process of laminating heat-sensitive stencil paper, so there are no problems with the working environment.

(3) It cures instantly by irradiating it with ultraviolet rays, so it has excellent productivity.

(4) The crosslinking density of the resin is high, 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) Adhesive strength is improved.

Claims (3)

[Claims] (1) In a heat-sensitive stencil paper formed by bonding a porous support and a thermoplastic synthetic resin film with an adhesive, the adhesive contains a polymerizable polyacrylate having two or more acryloyl groups and a photoinitiator. an ultraviolet curable adhesive, 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 type light A heat-sensitive stencil paper characterized by containing a sensitizer. (2) In a heat-sensitive stencil paper formed by bonding a porous support and a thermoplastic synthetic resin film with an adhesive, the adhesive contains a polymerizable polyacrylate having two or more acryloyl groups and a photoinitiator. A heat-sensitive stencil paper, which is an ultraviolet curable adhesive, characterized in that the photoinitiator contains (c) a tertiary amine photosensitizer and (d) a thioxanthone photoinitiator. (3) Claim (1) characterized in that the polymerizable polyacrylate having two or more acryloyl groups is mainly composed of epoxy acrylate or urethane acrylate.
Or the thermal stencil paper described in (2).