JP2938892B2 - Thermally copied stencil sheet and production method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a thermal copy base paper and a method for producing the same, and more particularly to provide a high-performance thermal copy base paper and an economical method for producing the same.

(Conventional technology and its problems) In the past, a copy printing method has been widely used as a simple printing method. In this method, a layer obtained by laminating a thermoplastic resin film layer on a suitable porous support surface such as paper is used. Used as a thermal copy plate, printed with a thermal head, etc.
The thermoplastic resin film layer is heated and melted to form image-like perforations, and printing is performed on a printing material such as paper through printing ink from the porous support side.

The thermal copying base paper used in the conventional thermal copying method is generally formed by laminating a thin thermoplastic resin film layer of about several μm on the surface of a porous support such as paper with an adhesive. Examples of the adhesive include (1) a solvent-based (or water-based) adhesive (for example,
Nos. 1188 and 47-1187).

In the case of a solvent-based adhesive, a large amount of solvent is used,
The cost is high, the working environment is difficult to maintain, the solvent resistance of the product is poor, and the ink used is limited.

Further, in the case of an aqueous adhesive, the amount of heat required for drying is enormous, and the heat during drying causes shrinkage of the thermoplastic resin film and dimensional change of the porous support, which causes curl and wrinkles. There's a problem.

(2) Solvent-free curable adhesives that solve the above-mentioned disadvantages of the solvent-type adhesives (JP-A-61-286131, JP-A-58-153697,
62-181374 and 63-233890.

Of these adhesives, in the case of a thermosetting adhesive,
The amount of heat required for curing is enormous, and furthermore, the thermoplastic resin film shrinks and the dimensional change of the porous support occurs during production, which causes a problem of curling and wrinkling.

Further, in the case of a room temperature-curable or moisture-curable adhesive, there is a problem that the curing speed is slow, the production takes an extremely long time, and the productivity is poor.

Further, in the case of an ultraviolet curable adhesive, the curing rate is slow, and when the irradiation amount is increased, the temperature rises significantly due to infrared rays other than ultraviolet rays, and this heat causes a problem of curling or wrinkling due to shrinkage of the thermoplastic resin film.

Further, as a general disadvantage of the useless adhesives, the viscosity of the adhesive is high, and it is difficult to apply a thin film to a thermoplastic resin film or a support. It is difficult to perform stably due to the viscosity of the adhesive.

When the adhesive is heated to reduce the viscosity, the thermoplastic resin film is deformed, and the application becomes difficult. Therefore, a method of applying an adhesive to the support (Japanese Patent Application Laid-Open No. 61-286131)
However, in this case, if the time required for curing is long, the adhesive is impregnated into the support, and there is a problem that a product having excellent resolution and image quality cannot be obtained.

Further, in the case of a curable adhesive, there is a problem that the heat melting property after curing is inferior and thus the perforation property is poor, and similarly, a product with high resolution and high image quality cannot be obtained.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned drawbacks and to economically provide a heat-sensitive copy base paper having excellent performance.

(Means for Solving the Problems) The above object is achieved by the present invention described below.

That is, the present invention comprises a polyurethane resin and a (meth) acrylate monomer on one surface of a porous support or a thermoplastic resin film, and a solid content of
An electron beam-curable adhesive diluted to 60% by weight or more is applied, a thermoplastic resin film or a porous support is laminated on the surface, and then the two are adhered by irradiating an electron beam. This is a method for producing a thermal copy base paper.

(Action) The adhesive composed of the polyurethane resin and the (meth) acrylate monomer has a remarkable temperature dependence of the viscosity. Therefore, when the adhesive is applied, by raising the temperature to a certain extent, the viscosity sharply decreases and excellent thin film coating becomes possible. When this adhesive is coated on a porous support in a thin film, the temperature of the adhesive decreases, but this temperature decrease causes the viscosity of the adhesive to rise sharply, and therefore the amount of impregnation into the porous support is significantly suppressed. As a result, a product having excellent resolution and image quality can be obtained.

In addition, by predominantly using a monofunctional monomer as the (meth) acrylic monomer, the adhesive layer can maintain the heat melting property, and therefore has a good perforation property. Can be done.

In addition, since the use of a solvent is substantially unnecessary, there is no problem of solvent recovery, and instant curing is possible by employing an electron beam as a curing means, so that a product having excellent adhesiveness and printing durability can be obtained. Provided with extremely high productivity.

(Preferred Embodiment) Next, the present invention will be described in more detail with reference to preferred embodiments.

The porous support used in the present invention, the printing ink used at the time of printing, it is necessary that it is porous so that it can pass through, for example, various paper, particularly open paper such as Japanese paper and rayon, Synthetic paper or mesh sheet made of chemical fiber such as vinylon, polyester, acrylonitrile, polyamide, etc., used as a porous support for conventional heat-sensitive copying base paper, such as paper made of a mixture of chemical fiber and Manila hemp, Kokuzo, Mitsumata natural fiber Any of these can be used in the present invention and is not particularly limited. For example, paper having a basis weight of about 8 to 12 g / m ² , synthetic paper, mixed paper, and the like are advantageously used.

The thermoplastic resin film layer itself laminated on the surface of the porous support is also used for the conventional heat-sensitive copying base paper, for example, a polyvinyl chloride film, a vinyl chloride-vinylidene chloride copolymer film, a polyester film, Polyethylene films such as polyethylene and polypropylene, polystyrene films and the like can be used, and these thermoplastic resin film layers are formed such that perforations are easily formed by heating means such as a thermal head.
Its thickness is 20 μm or less, preferably 10 μm or less, and most preferably 2 to 5 μm.

The adhesive used for bonding the porous support and the thermoplastic resin film layer mainly characterizes the present invention. In the present invention, an electron beam-curable adhesive comprising a polyurethane resin and a (meth) acrylate monomer Use

The polyurethane resin used in the adhesive is obtained from a polyisocyanate and a polyol, and has a high cohesive force due to the presence of a urethane bond. When this is mixed with a (meth) acrylate monomer, the viscosity has a significant temperature dependency. Things.

As such a polyurethane resin, various grades are available from the market, and any of them can be used in the present invention. Particularly preferred in the present invention is a reaction between a polyisocyanate, a polyol and a monofunctional alcohol. It is obtained by doing.

Examples of the polyisocyanate used include, for example, toluidine diisocyanate, 4,4'-diphenylmethane diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, and the like, and polyols such as 1,4-butanediol and 1,3- Butanediol, mono (or di, tri,
Tetra) ethylene glycol, mono (or di, tri, tetra) propylene glycol, 1,6-hexamethylene diol, etc., and as the alcohol, methyl alcohol, ethyl alcohol, n-propyl alcohol,
i-propyl alcohol, n-butyl alcohol, t-
Butyl alcohol, methyl cellosolve, ethyl cellosolve and the like.

The polyurethane resin composed of the above components is reacted at an equivalent ratio of isocyanate / polyol + alcohol = about 0.8 to 1.1, and the equivalent ratio of polyol / alcohol is preferably about 1/9 to about 1. If the amount of the alcohol used is too small, the molecular weight of the obtained polyurethane resin becomes too high, and the temperature dependence of the viscosity decreases.On the other hand, if the amount of the alcohol used is too large, the molecular weight of the polyurethane resin becomes too low, and the adhesiveness becomes low. Is undesirably reduced. Therefore, the molecular weight of the polyurethane resin used in the present invention is preferably in the range of about 500 to 1,500.

The (meth) acrylate monomer used in the present invention may be a commercially available one, for example,
2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, N-
Examples include methylol (meth) acrylate, N, N'-diethylaminoethyl (meth) acrylate, (meth) acryloyloxyethyl monosuccinate, (meth) acryloyloxyethyl monophthalate, and the like. For the purpose of improving the adhesiveness, a small amount of a polyfunctional (meth) acrylate monomer or the like can be used in combination as long as the thermal melting property of the adhesive layer is not impaired.

The mixing ratio between the polyurethane resin and the (meth) acrylate monomer is such that the viscosity of the mixture is 400 cps or less at 85 ° C. and 1,200 cps or more at 70 ° C.
It is preferable from the viewpoints of coating properties on the porous support and impregnation prevention properties. The specific mixing ratio varies depending on the molecular weight of the polyurethane resin used, the type of the (meth) acrylate monomer, and the like, but the weight ratio of the polyurethane resin / (meth) acrylate monomer = 60 to 90/40 to 10 is preferable.
Further, in order to adjust the coating property, a volatile solvent such as methyl ethyl ketone or ethyl acetate may be used in a small amount, for example, solid content (polyurethane resin + (meth) acrylate monomer).
May not be less than 60% by weight. In this case, the coatability of the adhesive to the thermoplastic resin film is improved, and the film surface is not deformed or wrinkled. Adhesive can be applied well and thinly. Of course, when the adhesive contains a small amount of solvent, it is preferable to evaporate the solvent before curing the adhesive.

The heat-sensitive copy plate base paper of the present invention is mainly characterized in that the thermoplastic resin film layer and the porous support are bonded to each other with the above-mentioned electron beam-curable adhesive. When no organic solvent is contained, it is preferable to apply the composition to the porous support side. On the other hand, when a small amount of solvent is contained, good application can be made to the thermoplastic resin film side.

Conventionally, when an electron beam-curable adhesive provided with appropriate fluidity by heating is applied to the porous porous support side, the electron beam-curable adhesive soaks into the porous support,
Although good quality products cannot be obtained, the adhesive used in the present invention has a remarkable temperature dependence of viscosity as described above,
By raising the temperature to a certain extent during the application of the adhesive, an excellent thin film application is possible.

On the other hand, when this adhesive is coated on a porous support in a thin film,
Although the temperature of the adhesive decreases, the decrease in the temperature sharply increases the viscosity of the adhesive, so that the amount of impregnation into the porous support is significantly suppressed.

The coating method is preferably a multi-roll coating method, but may be 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, or the like, and is not particularly limited.

If the coating amount is too large, the heat piercing property at the time of plate making decreases, and if the coating amount is too small, a problem occurs in the adhesive strength. Therefore, for example, a thickness of about 0.5 to 5 μm is preferable.

When the adhesive is solvent-free, the coating is preferably performed at a temperature at which the adhesive has sufficient application characteristics, for example, at a temperature rise of about 80 to 90 ° C. When a solvent is contained, coating can be performed at room temperature.

After the application of the above-mentioned electron beam curable adhesive, the adhesive layer becomes non-fluid by cooling, but the adhesive layer retains a certain degree of adhesiveness or tackiness due to the presence of the monomer. Then, both the support and the film are laminated.

By irradiating an electron beam from the thermoplastic resin film layer side or the porous support side while laminating or after laminating to cure the adhesive layer, the two are firmly adhered to each other, and the heat-sensitive copying base paper of the present invention is obtained.

The electron beam may be irradiated from any surface of the laminate, and the irradiation device can use the conventional technology as it is, for example,
In the case of electron beam curing, it is emitted from various electron beam accelerators such as Cockloft-Walton type, Bande graph type, Resonant transformer type, Insulating core transformer type, Linear type, Electro curtain type, Dynamitron type, High frequency type etc. An electron beam or the like having an energy of 1 to 1,000 KeV, preferably 100 to 300 KeV is used, and the irradiation dose is preferably about 1 to 5 Mrad.

As described above, the heat-sensitive copying base paper of the present invention has excellent plate-making characteristics.However, when the copying head is formed by heating the thermoplastic resin film layer by a thermal head or another method, depending on the conditions, the thermal head may Adhering to the thermoplastic resin film layer and destroying the thermoplastic resin film layer,
When a copying hole is formed by exposure through a positive original film, the positive original film may stick.

In order to solve such a problem, it is preferable to form an anti-adhesion layer on the thermoplastic resin film layer. The anti-adhesion layer needs to be heat-fusible and non-adhesive. Examples of such heat-fusible resins include, for example, polytetrafluoroethylene, polychlorotrifluoroethylene, tetrafluoroethylene-hexafluoroethylene copolymer, fluororesins such as polyvinylidene fluoride, silicone resins, epoxy resins, and melamine resins. A phenol resin, a polyimide resin, a polyvinyl acetal resin, a polyvinyl butyral resin, a polyoxyethylene terephthalate, a polyethylene oxide resin and the like can be used. Fatty acid metal salts such as stearic acid, palmitic acid, lauric acid, oleic acid and other lithium, potassium, sodium, calcium, barium, aluminum and other metal salts, phosphate ester surfactants, polyoxyethylene type Active agent,
It is preferable to add a surfactant such as a mono-, di-alkyl phosphate or tri (polyoxyethylene alkyl ether) phosphate at a ratio of about 10 to 200 parts by weight per 100 parts by weight of the resin to form an anti-adhesion layer. .

The anti-adhesion layer composed of the above resin (and surfactant)
These materials may be dissolved or dispersed in an organic solvent or water to prepare a coating liquid, and the coating liquid may be formed on the surface of the thermoplastic resin film layer by an arbitrary method. If the thickness of the anti-adhesion layer is too large, the heat sensitivity is reduced and the formation of perforations becomes insufficient, so that it is preferable that the thickness is thin, for example, about 0.1 to 10 μm. The timing of forming the anti-adhesion layer is not particularly limited, and may be after or during the formation of the heat-sensitive copying base paper of the invention, or may be formed on a raw thermoplastic resin film.

(Effects) According to the present invention as described above, by using an electron beam-curable adhesive composed of a polyurethane resin and a (meth) acrylate monomer as an adhesive, resolution, image quality, adhesiveness, printing durability, etc. Is provided with extremely high productivity.

Examples Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. In the description, parts and% are based on weight unless otherwise specified.

Example 1 Polyurethane resin 80 parts Acrylic ester monomer (Aronix M570
0, manufactured by Toa Gosei Co., Ltd.) to prepare an electron beam curable adhesive having a viscosity of 750 cps at 85 ° C. and a viscosity of 1,500 cps at 70 ° C.

The above polyurethane resin was synthesized using the following composition and using di-n-butyltin dilaurate as a catalyst.

Tolylene diisocyanate 3 mol 1,3-butanediol 0.8 mol 1,4-butanediol 0.2 mol n-butanol 1.5 mol i-isopropyl alcohol 1.8 mol methylcellosolve 0.5 mol t-butanol 0.2 mol At 80 ° C, multi-roll coating on Manila hemp / polyester blend paper
After applying ² g / m ^{2 at} a rate of 2 μm, a 2 μm-thick polyethylene terephthalate film is pressed on the surface,
d irradiation and lamination. Further, a heat-sealing inhibitor composed of a silicone oil / polyester resin mixture was applied to the polyester film surface at a solid content of 0.5 g / m ² at a solid content to obtain a heat-sensitive copying base paper of the present invention.

Example 2 In place of the electron beam-curable adhesive in Example 1, an electron beam-curable adhesive having the following composition was used, and in the same manner as in Example 1, a heat-sensitive copying base paper of the present invention was obtained.

Polyurethane resin 70 parts Acrylic ester monomer (Aronix M570
0, manufactured by Toagosei Co., Ltd.) 25 parts Acrylic ester monomer (Aronix M560
0, manufactured by Toa Gosei Co., Ltd.) to prepare an electron beam curable adhesive having a viscosity of 950 cps at 85 ° C. and a viscosity of 2,000 cps at 70 ° C.

The above polyurethane resin was synthesized using the following composition and using di-n-butyltin dilaurate as a catalyst.

Tolylene diisocyanate 2 mol 1,3-butanediol 0.8 mol n-butanol 1.2 mol i-isopropyl alcohol 1.2 mol Example 3 An electron beam curable adhesive having the following composition was dried on the same polyester film as in Example 1 by drying at 2 g / after coating and drying so as to be m ^2, laminated to Manila hemp / polyester mixed paper,
Thereafter, it was cured by irradiation with an electron beam to obtain a heat-sensitive copy base paper of the present invention.

Polyurethane resin 72 parts Acrylic ester monomer (Aronix M570
0, manufactured by Toa Gosei Co., Ltd.) 8 parts Methyl ethyl ketone 20 parts The above polyurethane resin was synthesized with the following composition and using di-n-butyltin dilaurate as a catalyst.

Tolylene diisocyanate 2 mol 1,3-butanediol 1 mol i-isopropyl alcohol 2 mol Comparative Example 1 Polyester resin (Vylon 200, manufactured by Toyobo Co., Ltd.)
Was dissolved in methyl ethyl ketone at a solid content of 10% to prepare an adhesive paint. In the same manner as in Example 1, a heat-sensitive stencil sheet of a comparative example was obtained.

When the plate making and printing were performed at Ricoh Preport SS870 using the heat-sensitive stencil plate of the present invention and the comparative example,
The results in Table 1 below were obtained.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-233890 (JP, A) WO 89/1872 (WO, A1) (58) Fields investigated (Int. Cl. ⁶ , DB name) B41N 1/24 102

Claims (1)

(57) [Claims] 1. An electron beam curable material comprising a polyurethane resin and a (meth) acrylate monomer on one surface of a porous support or a thermoplastic resin film and diluted to a solid content of 60% by weight or more with a volatile solvent. A method for producing a heat-sensitive stencil sheet, comprising applying an adhesive, laminating a thermoplastic resin film or a porous support on the surface, and thereafter irradiating an electron beam to bond the two.