JPH04189593A - Thermal stencil paper and printing method - Google Patents

Abstract

PURPOSE:To provide raw paper excellent in feed properties, imparting excellent image quality and extremely low in cost, that is, to realize the cost reduction of printed matter by forming the raw paper by laminating a thermoplastic resin film to a porous support through an adhesive layer and specifying the thickness of the thermoplastic resin film and specifying the coating amount of the adhesive layer on a solid basis. CONSTITUTION:As the thermoplastic resin film laminated to the surface of a porous support, any one with thickness of 2.0-6.0mum known heretofore can be used. A film with thickness of 3.0-5.0mum composed of a polyethylene terephthalate homopolymer is especially pref. When the coating amount of the adhesive used in the adhesion of the porous support and the thermoplastic resin film layer is too much, perforation properties lower. and, when the coating amount is too little, the perforation properties are enhanced and a problem is generated in printing durability. Therefore, by the use of a solventless type electron beam curable adhesive, a raw paper excellent in printing durability can be obtained in a low coating amount of 0.1-0.5g/m<2>.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a base paper and a printing method used in a digital thermal mimeograph printing method in which perforation is performed using a heating element of a thermal head.

(Prior Art) Conventionally, a thin, full-surface glaze thermal head as shown in Figure 2 has been used as the thermal head of a digital thermal mimeograph printing machine. and improve contact properties (JP-A-60-147338, JP-A-60-208244 and JP-A-60-4835).
(See Publication No. 4, etc.) are being attempted.

On the other hand, as a method to improve the perforation property by devising the base paper, the physical properties of the thermoplastic resin film, such as melting point, film thickness, heat shrinkage rate,
Changing crystallinity etc. (JP-A-62-2829, JP-A-63-160883, JP-A-62-1989)
149496, Japanese Unexamined Patent Publication No. 62-282984, etc.) have been attempted. In particular, regarding the film thickness, when the film is made of polyethylene terephthalate homopolymer, the perforation property is satisfied only when the film is 2 μm or less, as shown in JP-A-60-48398.

Regarding adhesives, whether solvent-based or non-solvent-based, the solid content is 0.5 to 3 g/rr? It is coated (Japanese Patent Application Laid-Open No. 1-14
(Refer to Japanese Patent Publication No. 8591 and Japanese Unexamined Patent Publication No. 1589/1989)
.

(Problems to be Solved by the Invention) As shown in the second figure, when using a conventional thin, full-surface glaze thermal head as a thermal head, the heat generating part of the thermal head is concave. There is a problem in that the contact between the base paper and the film is poor, and the film is not sufficiently perforated to correspond to the heating element of the thermal head.

To solve this problem, the platen was heated (Japanese Unexamined Patent Publication No. 1983
-147338) or prevent heat radiation to the platen (see Japanese Patent Application Laid-Open No. 60-48354).
Since it is the porous support of the base paper that comes into contact with the platen, it is not effective (there is also the problem that it consumes a lot of power).

Furthermore, a method of combining a thick-film type thermal head with a convex heat generating part and a thin-type thermal head (Japanese Unexamined Patent Application Publication No. 1983-1999)
208244), which is considered to be effective in terms of perforation, but the thick-film type head has large variations in the resistance value of the heating element, making it impossible to obtain holes corresponding to the size of the heating element. There is a problem.

On the other hand, the physical properties of the thermoplastic resin film used as the base paper, especially the film thickness, are thinner than 2 μm (the more perforation improves, but the production cost of the film becomes extremely high, and the rigidity of the base paper is insufficient, making it difficult to use in the printing machine). There is a problem that the transportability is poor.

In addition, it is effective to lower the melting point of the film by making the resin a copolymer (see JP-A-62-2829), but by making the resin a copolymer, heat resistance,
Since solvent resistance etc. are reduced, processing suitability when laminating with a porous support and storage stability of the base paper are poor. In addition, since the temperature dependence of the viscosity is low, there is leakage property, and the effect on perforability is smaller than expected.

As for adhesives, there is a problem that the amount of application is large (the printing durability improves as the amount increases, but the perforability deteriorates.
When a solvent-based adhesive is used, there is a problem in that skin formation occurs between the fibers during drying, which deteriorates not only the perforability but also the permeability of ink.

Therefore, an object of the present invention is to provide a thermal mimeograph base paper and a printing method that solve the above problems.

(Means for solving problems) The above objects are achieved by the present invention as described below.

That is, the present invention provides a thermal mimeographing plate used in a thermal mimeograph printing method in which a heating element of a thin partial glaze thermal head generates heat according to digital signals of images and characters, and a base paper film is perforated in synchronization with the digital signals. A base paper, wherein the base paper is formed by laminating a thermoplastic resin film on a porous support via an adhesive layer, and the thermoplastic resin film has a thickness of 2.0 to 6.0 μm. Moreover, the coating amount of the adhesive layer is 0. 1~0
．． 5g/lr? A thermal mimeograph base paper and a printing method characterized by the following.

(Function) To solve the above-mentioned problems of the conventional technology (as a result of various studies, it was found that a thin partially glazed thermal head as shown in the first figure was used as the thermal head of a digital thermal mimeograph printing tank, and the thickness of the thermoplastic resin film of the base paper was reduced. The film is 2.0 to 6.0 μm, and the solid content coating amount of the adhesive layer is 0.1 to 0.5.
The above problem was solved by using a base paper of g/rrr.

(Preferred Embodiments) Next, the present invention will be described in more detail by citing preferred embodiments.

The thermal mimeograph printing machine used in the present invention is a printing machine similar to that of the prior art except for the structure of its thermal head, and is not particularly limited.

As shown in the first diagram, the above-mentioned specific thermal head has a convex glaze layer on a ceramic substrate, the surface of which is covered with a heating element, electrodes on both sides, and a protective layer on the entire surface. . On the other hand, in the conventional full-surface glaze thermal head, a flat glaze layer is provided on the entire surface of the ceramic substrate as shown in Figure 2, a heating element is coated on that surface, and an electrode is arranged on the same side. A protective layer is provided.

The thin partial glaze thermal head shown in the first figure above has little variation in resistance value, produces perforations corresponding to the heating elements, and has a convex shape that improves contact with the base paper film, making the film relatively thick. The perforability is significantly improved even if the material is

The porous support of the base paper of the present invention, like the conventionally known heat-sensitive mimeograph base paper, needs to be porous so that the printing ink used during printing can pass therethrough.For example, rayon, vinylon, polyester, Examples include porous supports such as mixed paper and nonwoven fabrics made of chemical fibers such as acrylonitrile and polyamide and natural fibers of Manila hemp, paper mulberry, and mitsumata.

If the thermoplastic resin film laminated on the surface of the porous support has a thickness of 2.0 to 6.0 μm,
Any conventionally known thermoplastic resin film may be used. Particularly preferred is a polyethylene terephthalate homopolymer having a thickness of 3.0 to 5.
．． It is a 0 μm film. Films made of these polyethylene terephthalate homopolymers have a high temperature dependence of melt viscosity, so only the heated portions are easily perforated, and holes corresponding to the heating elements of the thermal head are formed, improving image quality. Moreover, the cost is low.

If the thickness of the thermoplastic resin film is less than 2 μm, the perforation properties will be further improved, but if it becomes too thin, the diameter of the perforated holes will become large, and the amount of ink transferred will increase, causing the problem of set-off. In addition, as the paper becomes thinner, the stiffness of the base paper decreases,
Problems arise in conveyance within the printing press. There is also the problem that as the thickness becomes even thinner, the cost increases rapidly.On the other hand, if the thickness exceeds 6.0 μm, even if a thin partial glaze thermal head is used, it will not perforate, but if the thickness is 2 to 6 μm This range is preferable because it improves the stiffness of the base paper while maintaining excellent perforation properties and sharply reduces the cost.

The adhesive used to bond the porous support and the thermoplastic resin film layer may be any conventionally known adhesive, but in the present invention, a solvent-free electron beam curable adhesive, particularly a polyurethane resin It is preferable to use a radiation-curable adhesive consisting of a monofunctional and/or (meth)acrylate.

The adhesive layer is formed by adding other additives and viscosity-adjusting solvents to the above adhesive as necessary, and applying multi-roll coating method, blade coating method, gravure coating method, knife coating method, reverse roll coating method. The layer may be formed by coating it on a porous support or a thermoplastic resin film by a spray coating method, an offset gravure coating method, a kiss coating method, etc., and the layer formation method is not particularly limited.

If the amount of adhesive applied is too large, the perforability will decrease, and if it is too small, the perforation will improve, but this will cause problems in printing durability. A base paper with excellent rigidity resistance can be obtained with a low coating amount of .1 to 0.5 g/rrr. Since the adhesive is solvent-free, it does not impregnate the porous support even if the film is relatively thick, and since the amount applied is small, a base paper with extremely excellent perforation properties is provided. On the other hand, since it is an electron beam curing type, the crosslinking density is high, and printing durability can be improved even with a low coating amount8.

After application of the electron beam curable adhesive, the adhesive layer becomes non-fluid due to cooling, but the adhesive layer maintains a certain degree of adhesiveness or tackiness due to the presence of the monomer.
In this state, both the support and the film are laminated.

By irradiating the adhesive layer with an electron beam from the thermoplastic resin film side or the porous support side during or after lamination to harden the adhesive layer, the two are firmly bonded.
A thermal mimeograph base paper of the present invention is obtained.

The electron beam can be irradiated from any side of the laminate (conventional technology can be used as the irradiation device; for example, Cockroft-Walton type, Bumpgraph type, resonant transformation type,
50 to 1,0 OOKeV, preferably 100
An electron beam or the like having an energy of ~300 KeV is used, and the irradiation dose is preferably about 1-5 Mrad.

The thermal mimeograph base paper of the present invention as described above has excellent plate-making properties, but when the thermal head heats the thermoplastic resin film to form the mimeograph holes, depending on the conditions, the thermal head may There is a risk of fusion and destruction of the thermoplastic resin film.

In order to solve such problems, it is preferable to form a heat fusion prevention layer made of silicone oil, silicone resin, surfactant, or these and a binder resin on the thermoplastic resin film.

The heat fusion prevention layer may be formed by dissolving or dispersing necessary materials in an organic solvent or water to prepare a coating solution, and applying this to the surface of the thermoplastic resin film by any method.

The thickness of the heat fusion prevention layer is preferably thin, since if it is too thick, the heat sensitivity will be reduced and the formation of perforations will be insufficient, and for example, a thickness of about 0.1 to 10 μm is preferable.

There is no particular limitation on the timing of forming this heat-fusion prevention layer, and it may be formed after or during the formation of the heat-sensitive mimeograph base paper of the present invention, or it may be formed on the original thermoplastic resin film.

(Example) Hereinafter, the present invention will be explained in more detail by giving Examples and Comparative Examples. In the text, parts or percentages are based on weight unless otherwise specified.

Example 1 Electron beam curable adhesive consisting of 76 parts of electron beam curable polyurethane resin and 20 parts of acrylic acid ester monomer (Aronix M5700, manufactured by Toagosei ■) was applied to Manila hemp/polyester fiber mixed paper with a weight of 10 g/rf. 90 drugs
While heating at ℃, it was coated with a solid content of 0.3 g/r& by multi-roll coating method, and 3.0
After laminating a polyethylene terephthalate homopolymer film with a thickness of μm, the adhesive layer was cured by irradiation with an electron beam of 3 Mrad. Furthermore, a heat-adhesive inhibitor consisting of a silicone oil/polyester resin mixture was coated on the surface of the polyester film at a solid content of 0.1 g/rrr to obtain a thermal mimeograph base paper of the present invention.

Examples 2 to 5 and Comparative Examples 1 to 3 The present invention and comparative examples were prepared in the same manner as in Example 1 except that the amounts of the thermoplastic resin film and adhesive applied in Example 1 were changed as shown in Table 1 below. A thermal mimeograph paper was obtained.

Usage Example: After making a plate using the thermal mimeograph base paper of the present invention and the comparative example described above with an experimental plate making machine equipped with a thin partial glaze thermal head and a full glaze thermal head, printing was performed with a Recover Report 5S950 to determine the density of the printed matter. and the resolution was evaluated.

0...Excellent ○...Good △・・・Inferior ×... Not practical.

(Effects of the Invention) According to the present invention as described above, it is possible to realize a low-cost base paper, that is, a printed matter, which has excellent transportability and image quality and is extremely low in cost. In this invention, the above-mentioned effects can be obtained by using a thin partially glazed thermal head to improve contact with the film, and by making a base paper using a thick film at a low cost with excellent perforation suitability and rigidity. It depends.

[Brief explanation of drawings]

FIG. 1 is a diagram illustrating the structure of a thin partial glaze thermal head. FIG. 2 is a diagram illustrating the structure of a thin, full-surface glaze thermal head.

Claims (4)

[Claims] (1) A thermal mimeograph base paper used in a thermal mimeograph printing method in which a heating element of a thin partial glaze thermal head generates heat in accordance with digital signals of images and characters, and a film of the base paper is perforated in synchronization with the digital signals. The base paper is formed by laminating a thermoplastic resin film on a porous support via an adhesive layer, and the thermoplastic resin film has a thickness of 2.0 to 6.0 μm, and the adhesive The coating amount of the layer is 0.1 to 0.5 g/m^ in terms of solid content.
A heat-sensitive mimeograph base paper characterized by two things. (2) The thermal mimeograph base paper according to claim 1, wherein the adhesive is an electron beam-curable solvent-free adhesive. (3) The heat-sensitive mimeograph base paper according to claim 1, wherein the thermoplastic resin film is a polyethylene terephthalate homopolymer film. (4) In a thermal mimeograph printing method in which a heating element of a thin partial glaze thermal head is made to generate heat according to digital signals of images and characters, and a film of a base paper is perforated in synchronization with the digital signal, the base paper is porous. A thermoplastic resin film is laminated on a support via an adhesive layer, and the thermoplastic resin film has a thickness of 2.0 to 6.0 mm.
1. A thermal mimeograph printing method, characterized in that the adhesive layer has a coating weight of 0.1 to 0.5 g/m^2 in solid content.