JP2002030261A - Ultraviolet light-curing adhesive composition and heat- sensitive stencil printing base paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultraviolet light-curing adhesive composition which don't make a thermal head dirty when a heat-sensitive stencil printing base paper is produced by using the above adhesive composition and excellent in adhesive strength between a porous support and a thermoplastic resin film and thereby capable of providing a heat-sensitive stencil printing base paper excellent in water resistance and solvent resistance and provide the heat- sensitive stencil printing base paper. SOLUTION: This ultraviolet light-curing adhesive composition for production of heat-sensitive stencil printing base paper comprises a resin having 50-250 deg.C glass transition point, an ultraviolet light-curing compound and a photopolymerization initiator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultraviolet-curable adhesive composition which is effective for producing a heat-sensitive stencil sheet, and can be awarded in the heat-sensitive stencil sheet and in the technical field for producing the same. .

[0002]

2. Description of the Related Art As heat-sensitive stencil printing paper, base paper in which a thin thermoplastic resin film of about several μm is adhered to a surface of a porous support such as paper with an adhesive is generally used. As the adhesive used in this case, a solvent-based or water-based adhesive is used.
7-1188 and 47-1187, etc.) In the case of a solvent-based adhesive, a large amount of solvent is used, so that cost is required for its recovery, the working environment is deteriorated, and further obtained products are obtained. However, there is a problem that the solvent resistance is poor and the ink used is limited. In the case of a water-based adhesive,
The amount of heat required for drying is enormous, and the heat at the time of drying causes shrinkage of the thermoplastic resin film and dimensional change of the porous support, resulting in curling and wrinkling.

In order to solve such a problem, use of a non-solvent type adhesive such as a thermosetting type, a room temperature setting type, a moisture setting type, and an ultraviolet setting type has been proposed (Japanese Patent Application Laid-Open No. 61-28).
Nos. 6131 and 58-153697 and 62
181374, 63-233890, etc.). However, in the case of a thermosetting adhesive, the amount of heat required for curing is enormous, and furthermore, shrinkage of the thermoplastic resin film and dimensional change of the porous support occur during production,
There is a problem that curls and wrinkles occur. Further, in the case of a room-temperature-curable or moisture-curable adhesive, there is a problem that the curing speed is slow, a long time is required for producing base paper, and productivity is poor.

[0004]

The ultraviolet-curing adhesive is excellent without the above-mentioned problems. However, one of the adherends in the heat-sensitive stencil sheet is a porous support, so that the adhesive layer is in contact with the atmosphere, and the thickness of the adhesive applied in this application is very thin, 0.1 to 5 μm. Therefore, the dissolved oxygen concentration in the adhesive coating film becomes extremely high, and rapid curing cannot be performed due to polymerization inhibition by oxygen, and curing is often insufficient. This is mainly due to the fact that uncured components contaminate the surface of the heating element of the thermal head and the adhesive strength between the porous support and the thermoplastic resin film is insufficient when the thermal stencil sheet is perforated with the thermal head. In addition, the resulting heat-sensitive stencil sheet has a problem that the water- and solvent-resistance is insufficient. In Japanese Patent Publication No. 7-106678,
In order to reduce the influence of oxygen inhibition of the adhesive, 2-methyl [4- (methylthio) phenyl] -2-morpholino-propanone-1 and a tertiary amine-based photoinitiator or An adhesive using a tertiary amine-type sensitizer or a combination of a tertiary amine-type photosensitizer and a thioxanthone-based photopolymerization initiator has been proposed. However, when the former photopolymerization initiator is blended, the curing speed may be insufficient when irradiating ultraviolet rays from the thermoplastic film side, and when the latter photopolymerization initiator is blended, the surface Curability was sometimes insufficient. The present inventors obtain a heat-sensitive stencil sheet using an ultraviolet-curable adhesive without contaminating a thermal head and having excellent adhesive strength between a porous support and a thermoplastic resin film. The present inventors have conducted intensive studies in order to find an ultraviolet-curable adhesive composition and a heat-sensitive stencil sheet whose heat-sensitive stencil sheet has excellent water resistance and solvent resistance.

[0005]

Means for Solving the Problems In view of the above problems, the present inventors have made various studies and found that an ultraviolet-curable adhesive composition containing a resin having a specific glass transition point was obtained.
The present inventors have found that the above-mentioned problems can be solved, and have completed the present invention. Hereinafter, the present invention will be described in detail. In this specification, an acryloyl group or a methacryloyl group is represented as a (meth) acryloyl group, acrylic acid or methacrylic acid is represented as (meth) acrylic acid, and acrylate or methacrylate is represented as (meth) acrylate.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The ultraviolet-curable adhesive composition of the present invention comprises a resin having a glass transition point of 50 to 250 ° C., an ultraviolet-curable compound and a photopolymerization initiator. Hereinafter, each component will be described.

Resin The composition of the present invention contains a resin having a glass transition point (hereinafter referred to as Tg) in the range of 50 to 250 ° C. as an essential component. A resin having a Tg of less than 50 ° C makes it easier for uncured or semi-cured components of the cured product to adhere to the heating element of the thermal head, while a resin having a temperature of more than 250 ° C is used for dissolving the resin when producing the composition. It is necessary to heat at a high temperature, it takes a long time to dissolve, and further, the composition is deteriorated by heating. In this specification, Tg is
It refers to the temperature at the inflection point of the curve obtained from the value measured by the differential scanning calorimeter.

The mixing ratio of the resin is preferably from 0.1 to 50% by mass, more preferably from 0.5 to 10% by mass, based on the total amount of the composition from the viewpoints of curability and coatability. If the ratio is outside the upper and lower limits, the curing of the composition becomes insufficient in any case, and the cured product may contaminate the thermal head. As the weight average molecular weight of the resin,
1,000 to 1,000,000 is preferred.

Specific examples of the resin include epoxy resin, phenol resin, urethane resin, ester resin, ketone formaldehyde resin, novolak resin, xylene resin,
Resins such as diallyl phthalate resin, styrene resin, guanamine resin, natural rubber, synthetic rubber, acrylic resin and polyolefin resin, and modified products thereof. Among them, epoxy resin, diallyl phthalate resin, styrene resin and acrylic resin are preferable because the effect of improving the adhesive strength between the porous support and the thermoplastic resin film and the printing durability of the base paper is great, and diallyl phthalate is preferable. Resins, styrene resins and acrylic resins are more preferred.

The ultraviolet-curable compound used in the composition of the present invention is preferably a compound having a (meth) acryloyl group. As the compound having a (meth) acryloyl group,
Both monomers and oligomers can be used. The compounding ratio of the ultraviolet curable compound is preferably 50 to 99.9% by mass in the composition, more preferably 9 to 99.9% by mass.
0 to 99.5% by mass. When higher adhesive strength and durability (prevention of deterioration) are required, it is preferable to use a mixture of oligomers having two or more (meth) acryloyl groups. In this case, the ratio of the monomer to the oligomer is 20 to 100 based on the total amount of the monomer having one or more (meth) acryloyl groups and the oligomer having two or more (meth) acryloyl groups.
The latter is preferably 5 to 80% by mass at 95% by mass, and more preferably the former is 50 to 95% by mass and the latter is 5 to 50% by mass.

As the monomer, a compound having one (meth) acryloyl group [hereinafter referred to as a monofunctional (meth) acrylic monomer], a compound having two or more (meth) acryloyl groups [hereinafter referred to as a polyfunctional (meth) acrylate] Acrylic monomer]. Examples of the monofunctional acrylic monomer include an acrylic monomer having a ring structure such as an aliphatic ring, an aromatic ring and a heterocyclic ring, and an aliphatic acrylate having a hydroxyl group. Examples of the (meth) acrylic monomer having a ring structure such as an aliphatic ring, an aromatic ring, or a heterocyclic ring include tricyclodecane (meth) acrylate, dicyclopentenyl (meth) acrylate, isobornyl (meth) acrylate, and adamantyl ( Examples thereof include (meth) acrylate, phenyl (meth) acrylate, benzyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, morpholine acrylate, and phenylglycidyl (meth) acrylate. Moreover, these alkylene oxide modified products can also be used. In particular, modified alkylene oxides having 2 to 3 carbon atoms, such as dicyclopentenyloxyethyl (meth) acrylate and phenyloxyethyl (meth) acrylate, are preferred.

As the aliphatic (meth) acrylate having a hydroxyl group, for example, a (meth) acrylate in which a hydroxyl group is bonded to an aliphatic group having 2 to 9 carbon atoms is preferable, and a fatty acid having 2 to 4 carbon atoms is more preferable. It is a (meth) acrylate in which a hydroxyl group is bonded to a group. A substituent such as a phenoxy group may be bonded to the aliphatic (meth) acrylate. Examples of the (meth) acrylate include 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and 2-hydroxy-3
-Phenoxypropyl (meth) acrylate and the like.

Among the above-mentioned monofunctional (meth) acrylic monomers, particularly preferable ones from the viewpoint of maintaining viscosity, wet heat resistance and adhesiveness include, for example, phenyloxyethyl (meth) acrylate and tricyclodecane (meth) acrylate. , Isobornyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, morpholine acrylate, 2-hydroxyethyl (meth) acrylate and 2-hydroxy-3-phenoxypropyl (meth) acrylate.

The polyfunctional (meth) acrylic monomer is
There are functional (meth) acrylic monomers and trifunctional or higher functional (meth) acrylic monomers. Examples of the bifunctional (meth) acrylic monomer include an acrylate compound of an aliphatic diol having 4 to 9 carbon atoms, an alkylene oxide type (meth) acrylic monomer, and a (meth) acrylic monomer having a ring structure. 4-9 carbon atoms
Examples of the aliphatic diol acrylate compound include neopentyl glycol di (meth) acrylate,
Examples include 1,6-hexanediol di (meth) acrylate. The (meth) acrylate of the aliphatic diol may be modified with an aliphatic ester or an alkylene oxide. Examples of the aliphatic ester-modified acrylate compound include neopentyl glycol hydroxypivalate di (meth) acrylate and caprolactone-modified neopentyl glycol hydroxypivalate di (meth) acrylate.

Examples of the alkylene oxide-modified (meth) acrylate include diethylene oxide-modified neopentyl glycol di (meth) acrylate and dipropylene oxide-modified neopentyl glycol di (meth) acrylate.
Examples include acrylate, diethylene oxide-modified 1,6-hexanediol di (meth) acrylate, and dipropylene oxide-modified 1,6-hexanediol di (meth) acrylate. Examples of the alkylene oxide type (meth) acrylic monomer include neopentyl glycol-modified trimethylolpropane di (meth) acrylate, polyethylene glycol di (meth) acrylate, and polypropylene glycol di (meth) acrylate. Examples of the (meth) acrylic monomer having a ring structure include tricyclodecane dimethylol di (meth) acrylate and dicyclopentanyl di (meth) acrylate.

The trifunctional or higher functional (meth) acrylic monomer includes, for example, trimethylolpropane tri (meth)
Acrylate, pentaerythritol tri (meth) acrylate, aliphatic modified dipentaerythritol penta (meth) acrylate having 2 to 5 carbon atoms, aliphatic modified dipentaerythritol tetra (meth) acrylate having 2 to 5 carbon atoms, dipentaerythritol penta (Meth) acrylate, dipentaerythritol hexa (meth) acrylate, caprolactone-modified dipentaerythritol hexa (meth) acrylate, pentaerythritol tetra (meth) acrylate, tris [(meth) acryloxyethyl] isocyanurate, caprolactone-modified tris [( (Meth) acryloxyethyl] isocyanurate and ditrimethylolpropanetetra (meth) acrylate. Among the above polyfunctional (meth) acrylic monomers, particularly preferred from the viewpoint of maintaining viscosity, wet heat resistance and adhesiveness, bifunctional (meth) acrylic monomers include, for example, neopentyl glycol di (meth) acrylate, Aliphatic diol acrylate compounds having 4 to 9 carbon atoms such as 1,6-hexanediol di (meth) acrylate, neopentyl glycol hydroxypivalate di (meth) acrylate, and caprolactone-modified neopentyl glycol hydroxypivalate di (meth) acrylate ) Aliphatic ester-modified aliphatic diol acrylates such as acrylates. Examples of tri- or more functional acrylic monomers include dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and tris [(me ) Acryloxyethyl] isocyanurate and caprolactone-modified tris [(meth) acryloxyethyl] isocyanurate.

The amount of these monomers used is preferably from 5 to 90% by mass in the composition. These monomers may be used singly or in combination of two or more at an arbitrary ratio. However, from the viewpoint of viscosity, a monofunctional (meth) acrylic monomer or a bifunctional (meth) acrylic monomer may be used. It is preferable to use a (meth) acrylic monomer having three or more functional groups, if necessary.

The oligomer having two or more (meth) acryloyl groups is preferably used in combination with the above-mentioned monomer when higher adhesive strength and durability (prevention of deterioration) are required as described above. The oligomer is preferably one that dissolves in the above monomers. Examples of such an oligomer include epoxy (meth) acrylate, polyester (meth) acrylate and urethane.
(Meth) acrylate and the like. In the present invention, the oligomer means one having a molecular weight of 500 or more.

Epoxy (meth) acrylate is obtained by reacting an epoxy resin with (meth) acrylic acid. Examples of the epoxy resin include bisphenol type epoxy resins such as bisphenol A type epoxy resin and bisphenol F type epoxy resin, and novolak type epoxy resin. Epoxy resin is commercially available, for example, bisphenol A type epoxy resin,
For example, Epicoat 828 (trade name, manufactured by Yuka Shell Epoxy Co., Ltd., the same applies hereinafter), Epicoat 1001 and Epicoat 1004, and the like, and examples of bisphenol F type epoxy resins include Epicoat 4001P, Epicoat 4002P, and Epicoat 4003P. Examples of the novolak type epoxy resin include Epicoat 152 and Epicoat 154.

The polyester (meth) acrylate is obtained by reacting a polyester polyol with (meth) acrylic acid. The polyester polyol is obtained by a reaction between a polyhydric alcohol and a polybasic acid. Examples of the polyhydric alcohol include neopentyl glycol, ethylene glycol, propylene glycol, 1,6-hexanediol, trimethylolpropane, pentaerythritol, tricyclodecane dimethylol, and bis-
[Hydroxymethyl] -cyclohexane and the like. Examples of polybasic acids include succinic acid, phthalic acid, hexahydrophthalic anhydride, terephthalic acid, adipic acid,
Azelaic acid and tetrahydrophthalic anhydride;

The urethane (meth) acrylate is obtained by a reaction between a polyol, an organic polyisocyanate and a hydroxy (meth) acrylate compound, or an organic polyisocyanate and a hydroxy (meth) acrylate compound without using a polyol. And those obtained by the reaction of the two. Examples of the polyol include polypropylene glycol, polyether polyols such as polytetramethylene glycol, polyester polyol obtained by reacting the polyhydric alcohol with the polybasic acid, the polyhydric alcohol, the polybasic acid and ε
-Caprolactone polyol obtained by reaction with caprolactone, and polycarbonate polyol (for example, polycarbonate polyol obtained by reaction of 1,6-hexanediol and diphenyl carbonate). Examples of the organic polyisocyanate include isophorone diisocyanate, hexamethylene diisocyanate, tolylene diisocyanate, xylene diisocyanate, diphenylmethane-4,4'-
Examples include diisocyanate and dicyclopentanyl diisocyanate. The product obtained by the reaction of the three or the product obtained by the reaction of the two may be used alone or in combination.

Among these oligomers, epoxy (meth) acrylate or urethane (meth) acrylate is particularly preferable in terms of maintaining viscosity, wet heat resistance and adhesiveness. These oligomers may be used singly or in combination of two or more kinds at an arbitrary ratio.

○ Photopolymerization initiator Various photopolymerization initiators can be used in the composition of the present invention. For example, benzoin ethers such as benzoin ethyl ether, benzoin butyl ether and benzoin isopropyl ether; benzophenones such as 4,4'-bisdimethylaminobenzophenone and 4,4'-bisdiethylaminobenzophenone; acetophenone, 2,2-dimethoxy-2 -Phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone, 1-hydroxycyclohexylphenylketone, 2-methyl-1- [4
-(Methylthio) phenyl] -2-morpholino-propan-1-one, 2-benzyl-2-dimethylamino-1
-(4-morpholinophenyl) -butanone-1 and N,
Acetophenones such as N-dimethylaminoacetophenone; thioxanthones such as 2,4-diethylthioxanthone, 2-chlorothioxanthone and 2-isopropylthioxanthone; ketals such as benzyldimethyl ketal and acetophenone dimethyl ketal;
And phosphine oxides such as trimethylbenzoyldiphenylphosphine oxide. Among them, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-propan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1 However, the curing speed of the composition is high, and the deposition on the surface of the thermal head heating element is small even at a high production speed, which is preferable. These can be further used in combination with aminobenzophenones such as 4,4'-bisdimethylaminobenzophenone and 4,4'-bisdiethylaminobenzophenone and sensitizers such as tertiary amines to improve curability without oxygen inhibition. It is preferable because it becomes an excellent composition. A preferred blending ratio of the photopolymerization initiator is preferably 0.1 to 15% by mass based on the total amount of the composition.
More preferably, it is 0.5 to 10% by mass. If this ratio is less than 0.1% by mass, curing may be insufficient, while if it exceeds 15% by mass, the cured product may contaminate the thermal head.

Other components In addition to the above essential components, various components can be added to the composition of the present invention, if necessary. Specific examples include a silane coupling agent, a polymerization inhibitor, a leveling agent, a surface lubricant, an antifoaming agent, a light stabilizer, an antioxidant, an antistatic agent, and a filler. Examples of silane coupling agents include alkyl-based, amine-based, (meth) acrylate-based,
Isocyanate type, epoxy type and thiol type are exemplified. The amount of this silane coupling agent used is
Usually, 0 to 10% by mass relative to the total amount of the composition is preferred.
Examples of the polymerization inhibitor include methoquinone and methylhydroquinone. The use amount of this polymerization inhibitor is preferably from 0 to 1% by mass based on the total amount of the composition. Leveling agent,
Examples of the surface lubricant and antifoaming agent include organic polymer-based, silicon-based, and fluorine-based ones. As antioxidants, hindered amines, hindered phenols,
High-molecular-weight phenols and the like can be mentioned. These leveling agents, surface lubricants, defoamers, and antioxidants are usually used in an amount of 0 to 5% by mass based on the total amount of the composition.
Is preferred. Examples of the antistatic agent include quaternary ammonium, polyether, and conductive powder. The amount of the antistatic agent used is 0 to 3 with respect to the total amount of the composition.
0% by mass is preferred.

The adhesive composition used in the present invention has a remarkable temperature dependency of the viscosity, and the viscosity drops sharply only by slightly increasing the coating temperature, so that excellent thin film coating properties can be obtained. After coating the composition on a porous support,
A slight decrease in the temperature of the composition causes a sharp increase in the viscosity of the adhesive, so that the amount of the adhesive impregnated in the porous support is significantly suppressed, and a stencil sheet having excellent resolution and image quality is obtained. In addition to the above, an initial holding force for suppressing the peeling of the porous support and the thermoplastic film generated during the lamination is generated, and the laminating workability is improved.
The viscosity of the adhesive composition at 50 ° C. is 300 mPa ·
s or less and 1200 mPa · s or more at 25 ° C. It is preferable to mix the above-described components so as to obtain such a viscosity.
It is preferable in terms of initial holding power and impregnation prevention.

The method for producing the heat-sensitive stencil printing paper The adhesive composition of the present invention may be used according to a conventional method.
Specific examples include a method in which the composition of the present invention is applied to a thermoplastic resin film and / or a porous support, these are adhered to each other, and then irradiated with ultraviolet light to be cured and adhered.

As the thermoplastic resin film to which the composition of the present invention can be applied, for example, a polyester film, a polycarbonate film, a polypropylene film, a polyvinyl chloride-vinylidene chloride copolymer film and the like can be mentioned. A polyester film is generally used from the viewpoint of image quality. The thickness of the film is preferably 10 μm or less, more preferably 1 to 6 μm.
Further, a biaxially stretched film is usually used for the film,
Those having a stretching ratio of 150 to 400% in both the longitudinal and transverse directions are preferably used.

Examples of the material of the porous support include synthetic fibers such as polyester fiber, vinylon fiber and nylon fiber;
Natural fibers such as manila hemp, mulberry, honey, pulp and kenaf are used, and these can be used alone or in combination of two or more. The weight of the porous support is 6 to
15 g / m ² is preferable, and more preferably 8 to 13 g / m ²
m ² . Further, the thickness is preferably from 10 to 60 μm, more preferably from 15 to 55 μm.

As the method of applying the composition, a multi-roll coating method is preferable, but a blade coating method, a gravure coating method, a knife coating method, a reverse roll coating method, a spray coating method, an offset gravure coating method, a kiss coating method and the like are used. You may. The thickness of the coating film of the adhesive composition is preferably in the range of 0.01 to 2.0 μm.

The light source for curing the composition is not particularly limited. For example, a pressurized or high-pressure mercury lamp, a metal halide lamp, a xenon lamp, an electrodeless discharge lamp, a carbon arc lamp and the like can be used.
It is preferable to use a metal halide lamp or an electrodeless discharge lamp D bulb having a continuous wavelength between the emission wavelengths of 450 nm to 450 nm because the curing speed can be improved.

The heat-sensitive stencil sheet produced by the adhesive composition of the present invention has excellent plate-making properties. However, when the thermoplastic resin film is heated by a thermal head or another method to form perforations, Depending on the conditions, the thermal head adheres to the thermoplastic resin film to break the thermoplastic resin film, or when the perforation is formed by exposure through the positive original film, the thermoplastic resin film adheres to the positive original film May be. In order to solve such a problem, it is preferable to form an anti-adhesion layer having heat-fusibility and non-adhesion on a thermoplastic resin film. In order to obtain heat melting property, for example, polytetrafluoroethylene, polychlorotrifluoroethylene, tetrafluoroethylene, hexafluoroethylene copolymer, fluorine resin such as polyvinylidene fluoride, silicone resin, epoxy resin, melamine resin, phenol Resin, polyimide resin, polyvinyl acetal resin, polyvinyl butyral resin, polyoxyethylene terephthalate, polyethylene oxide resin, etc. are used. In order to further obtain the slipperiness (non-adhesiveness) of the anti-adhesion layer,
Surfactants, for example, stearic acid, palmitic acid, lauric acid, fatty acid metal salts such as metal salts such as lithium, potassium, sodium, calcium, barium, and aluminum such as oleic acid, phosphate ester type surfactants, polyoxyethylene Surfactants, mono-, dialkyl phosphates, tri (polyoxyethylene alkyl ether)
Phosphate esters and the like, or silicone oils and the like are used. The amount of the anti-adhesion layer is about 1 per 100 parts by mass of the resin.
It is preferable to add 0 to 200 parts by mass of a surfactant or the like. These materials are dissolved or dispersed in an organic solvent or water to prepare a coating liquid, and the coating liquid is formed on the surface of the thermoplastic resin film layer by an arbitrary method. It may be formed by coating on the surface. If the thickness of the anti-adhesion layer is too thick, the heat sensitivity is reduced, and the formation of perforations becomes insufficient, so the thinner is preferable, for example, about 0.001 to
A thickness of about 1 μm is preferred. The timing of forming the anti-adhesion layer is not particularly limited, and may be after the formation of the heat-sensitive stencil printing base paper, during the formation, or may be formed on a raw thermoplastic resin film.

[0032]

Generally, when an ultraviolet-curable adhesive is used when producing a heat-sensitive stencil sheet, the adhesive layer is in contact with the atmosphere because one adherend is a porous support. Since the coating thickness of the composition is as extremely small as 0.1 to 5 μm, the dissolved oxygen concentration in the coating film is extremely high, rapid curing cannot be performed, and curing inhibition is likely to occur. On the other hand, since the composition of the present invention contains a resin having a Tg of 50 to 250 ° C., gelation proceeds with the resin as a nucleus even in a state where the curing reaction rate of the composition is low. Is very thin, it can be efficiently cured by ultraviolet irradiation.
Further, internal stress due to volume shrinkage of the composition at the time of curing, which causes a reduction in adhesive strength, is reduced, and as a result, high adhesive strength can be obtained. Therefore, the uncured components are reduced, the amount of deposits on the heating element can be reduced, and the adhesive strength and printing durability can be improved.

[0033]

The present invention will now be described more specifically with reference to examples and comparative examples. Examples and Comparative Examples The components shown in Table 1 were stirred and mixed according to a conventional method to obtain an adhesive composition.

[0034]

[Table 1]

A-1: Acrylic resin [BR-60, manufactured by Mitsubishi Rayon Co., Ltd., Tg; 75 ° C.] A-2: Diallyl phthalate resin [Isodap, manufactured by Daiso Co., Tg; 165 ° C.] A-3: Styrene Resin [Johncryl 678, Tg; 85 ° C, manufactured by Johnson Polymer Co., Ltd.] A ': Acrylic resin [Alphon UH, manufactured by Toagosei Co., Ltd.]
2000, Tg; -55 ° C] B-1: Bisphenol A glycidyl ether diacrylate oligomer [Aronix TO manufactured by Toagosei Co., Ltd.
-1077] B-2: urethane acrylate oligomer [Aronix M1600 manufactured by Toagosei Co., Ltd.] B-3: 2-hydroxy-3-phenoxypropyl acrylate C-1: 2-benzyl-2-dimethylamino-1- (4
-Morpholinophenyl) -butanone-1 C-2: 2-methyl [4- (methylthio) phenyl]-
2-morpholino-propanone-1 C-3: 4,4'-bis (diethylamino) benzophenone C-4: 4-diethylaminoethylbenzoate

評 価 Evaluation Method A heat-sensitive stencil sheet was manufactured and evaluated according to the following method.・ Method of producing heat-sensitive stencil printing base paper Each UV-curable adhesive composition shown in Table 1 was heated to 40 ° C. on a surface of a 2 μm-thick polyester film using a roll coater, and coated at 0.8 μm. After coating to a thickness, weighing 12 g as a porous support
/ M ² polyester fiber 30% by mass and Japanese paper fiber 7
A mixed fiber paper containing 0% by mass was pressed. Immediately thereafter, ultraviolet light was irradiated from the polyester film side by an ultraviolet irradiation device to cure the adhesive, and the film and the support were bonded together. The irradiation distance from the lamp at this time is 100 mm
And the running speed was 50 m / min. Next, a release agent made of a silicone resin was added to the film surface of the base paper in an amount of 0.1 mm.
Coating was performed using a roll coater to a thickness of 2 μm to obtain a heat-sensitive stencil sheet. The resulting heat-sensitive stencil sheet was subjected to plate-making printing using a digital plate-making printing machine [Risograf GR275, manufactured by Riso Kagaku Kogyo KK]. The characteristics at this time were evaluated as follows, and the results are shown in Table 2.

1) Thermal Head Contamination Evaluation of the contamination of the thermal head (hereinafter referred to as TPH) was repeated up to 150 plates by continuous plate making of a solid portion, and thereafter, the change of the surface state of the heating element and the change of the print density of the printed matter were determined. It was observed and evaluated according to the following criteria. A: The surface of the TPH element was very clean, and there was no deposit, and a clear image having no influence on printing was obtained. ：: Some deposits were observed on the surface of the TPH element,
A clear image without affecting printing was obtained. X: A considerable deposit was observed on the surface of the TPH element, and white streaks caused by the deposit were observed in the printed matter.

2) Curability The curability was evaluated by peeling the film portion of the heat-sensitive stencil sheet immediately after irradiation with ultraviolet light from the porous support, observing the cured state of the adhesive adhering to the film by touch, and curing. Then, the presence or absence of tack (adhesion) was observed and evaluated according to the following criteria. ◎: Completely cured, no tack was observed. ：: Hardened but tacky. ×: Not cured at all.

3) Peel strength Peel strength of heat-sensitive stencil sheet (lamination adhesive strength)
Cuts a base paper with a kraft tape stuck on both sides for reinforcement into a test piece of 50 (CD direction) x 150 (MD direction) mm, a peel angle of 180 degrees and a peel speed of 300
The measurement was performed based on the magnitude of the peel strength per 50 mm between the film and the support under the conditions of m / min.

4) Water Resistance and Solvent Resistance Water resistance and solvent resistance were measured by measuring the peel strength of a test piece having the above peel strength after immersing it in pure water and a petroleum-based high boiling solvent at 40 ° C. for 24 hours. The water resistance and the solvent resistance were measured, respectively.

[0041]

[Table 2]

As is clear from the results in Table 2, the heat-sensitive stencil base paper obtained with the adhesive composition of the present invention (Example 1)
Nos. To 6) showed little TPH contamination, excellent adhesive curability, and excellent peel strength, water resistance and solvent resistance. In contrast, in the base papers of Comparative Examples 1 to 3, TPH contamination occurred, and the peel strength, water resistance, and solvent resistance were poor.

[0043]

According to the adhesive composition of the present invention, in the production of heat-sensitive stencil printing paper, it has excellent curing properties and can be completely cured with little tack even at a high production line speed. In addition, there is no adhesion of deposits on the surface of the thermal head heating element, stable thermal plate making properties are obtained, and clear printed matter is obtained, and there is no need for thermal head cleaning work, and the plate making workability is excellent. Further, the cured product is excellent in water resistance and solvent resistance and can firmly bond and bond the thermoplastic resin film and the porous support, so that the laminate adhesive strength is high and the printing durability is excellent.

Continued on the front page F-term (reference) 2H114 AB23 AB24 AB28 BA06 DA47 DA52 DA56 DA73 DA78 EA01 EA05 EA06 GA11 GA34 GA38 4F100 AK01A AK01B AK12 AK13 AK25 AK25J AK41 AK51 AK51J AL01 AR00B AT00C BA03 BA07 BA01B06 J10 J03B07 JL13B 4J040 CA011 CA012 CA031 CA032 DA011 DA012 DA091 DA092 DA131 DA132 DB021 DB022 DE041 DE042 DF021 DF022 EB011 EB012 EB021 EB022 EB031 EB032 FA EB081 EB082 EB141 EB142 FA001 FA 172 EB001 FA 263 JA01 JA12 JB08 KA13 LA01 LA02 MA09 MA10 MB03 NA21 PA32

Claims (5)

[Claims] 1. An ultraviolet-curable adhesive composition for producing heat-sensitive stencil printing paper, comprising a resin having a glass transition point of 50 to 250 ° C., an ultraviolet-curable compound and a photopolymerization initiator. 2. The ultraviolet-curable resin according to claim 1, wherein the resin having a glass transition point of 50 to 250 ° C. is at least one selected from diallyl phthalate resin, styrene resin and acrylic resin. Adhesive composition. 3. The ultraviolet-curable compound comprises 20 to 95% by mass of a monomer having one or more (meth) acryloyl groups and 5 to 80% by mass of an oligomer having two or more (meth) acryloyl groups. The ultraviolet-curable adhesive composition according to claim 1 or 2, wherein 4. The ultraviolet-curable adhesive composition according to claim 3, wherein the oligomer having a (meth) acryloyl group is an epoxy (meth) acrylate oligomer and / or a urethane (meth) acrylate oligomer. . 5. A heat-sensitive stencil sheet obtained by laminating a thermoplastic resin film and a porous support with the adhesive composition according to any one of claims 1 to 4.