JPS63212593A - Thermal stencil base paper - Google Patents

Abstract

PURPOSE:To print in high density without broken character or blurred character, to eliminate fog of printed matter due to an increase in the number of printed sheets, and to obtain preferable printing sensitivity and printability by providing a polymer layer which mainly contains copolymer of olefin monomer and acrylic monomer as a thermal stencil layer on one side surface of a porous sheet mate rial. CONSTITUTION:Olefin-acryl copolymer is provided as a coating layer on one side surface of a porous sheet material; the ratio of acrylic monomer is preferably 5-50wt.% and particularly 10-40wt.%. In the formation of a thermal stencil layer made of the coating layer, water is filled into the sheet material, and solution of olefin-acrylic copolymer dissolved in an organic solvent is applied. Then, since the air gap of the material is full of water, the applied solution is formed in a layer state, dried to form a polymer coating layer which has 2mum or less and normally 0.1-1.5mum thick and uniform without defect, such as fish eye on the material.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a heat-sensitive stencil paper having a heat-sensitive stencil layer provided on one side of a porous thin material.

[Conventional technology]

Conventionally, heat-sensitive stencil paper is produced by applying adhesive (including adhesive) to a film made in advance by stretching or inflation, such as polyvinylidene chloride film or polyethylene terephthalate (PET) film. It is manufactured by laminating a porous thin sheet material on this coated surface.

The heat-sensitive stencil paper produced by this method is one in which the above-mentioned film and adhesive layer together constitute a heat-sensitive stencil layer, and the plate is made by perforating these by heating,
During printing, this base paper is wrapped around an ink drum,
Printing is performed by supplying ink from the porous thin material side.

By the way, in such heat-sensitive stencil paper, the thickness of the heat-sensitive stencil layer is thick (this makes it difficult for ink supplied from the porous thin material side during printing to pass through, and also heat is generated around it during hot perforation). A large amount of molten polymer remains, resulting in poor plate-making accuracy and ink smearing during printing.As a result, high-density and clear printing cannot be performed, and printing sensitivity and image quality deteriorate. This has the disadvantage of causing

For this reason, it is desirable for the thickness of the heat-sensitive stencil layer to be as thin as possible.Thinness (thinner) improves plate-making accuracy and facilitates printing, and also allows the use of high-viscosity ink. Clear printing, that is, high-quality printing with good sensitivity and image quality, can be achieved.

However, in the conventional heat-sensitive stencil paper, there is a limit to the Ti1L heat-sensitive stencil layer, and it is difficult to make the heat-sensitive stencil layer as thin as 2 μm or less, for example, about 1 μm, which can be expected to improve the quality of printing.

The reason for this is that films such as polyvinylidene chloride film and PET film have a thickness of about 2 μm at most, and it is difficult to obtain films thinner than this at a low cost due to film-forming technology and demand. This is because even if it were available, it would be difficult to uniformly laminate it onto a porous thin sheet material using an adhesive. Another reason is that in order to adhere the above film to the porous thin material, it is usually about 0.5
~3g/rrr<solid content) of adhesive is required,
This is because the overall thickness of the heat-sensitive stencil layer becomes thicker accordingly.

Therefore, in view of the above-mentioned problems with the conventional heat-sensitive stencil paper, the inventors have made extensive studies, and as a result, the heat-sensitive stencil layer to be provided on the porous thin material is composed of a coating layer of a thermoplastic polymer. In other words, if the above layer is formed by coating a thermoplastic polymer, problems in terms of film forming technology, laminating technology, and economic efficiency when using the conventional film forming film or adhesive can be solved. It is completely avoided, and there is no obstacle to thinning the adhesive layer based on the adhesive layer. y, ~1°5μm
It was found that a very thin heat-sensitive stencil layer could be easily formed, and this was already proposed as a prior invention of the present invention.

The heat-sensitive stencil paper according to this prior invention has a unique structure in which the heat-sensitive stencil layer is composed of a single layer (coating layer) of a thermoplastic polymer without an adhesive layer, unlike the above-mentioned conventional stencil paper. It has many advantages, such as being able to easily make the layer thinner, making it easier to achieve higher quality printing, and being able to manufacture it at a lower cost.

[Problem that the invention seeks to solve]

However, according to the inventors' subsequent research, the heat-sensitive stencil paper according to the above-mentioned prior invention sometimes lacks the durability of the polymer coating layer, and when it is plate-made and printed, the durability of the polymer coating layer is sometimes lacking, and as the number of printed sheets increases, The coating layer deteriorated and capri (background stains) appeared on the printed matter. In addition, for those with few such problems, the printing sensitivity tends to be somewhat insufficient, and in this case, it is difficult to perform high-density printing without blurring or blurring of characters.

Therefore, this invention further improves the above-mentioned prior invention, and not only enables high-density printing without missing or blurred characters, but also improves printing sensitivity and printing durability without the problem of capri of printed matter due to an increase in the number of printed sheets. The purpose of the present invention is to provide a heat-sensitive stencil paper with good properties.

[Means for solving problems]

As a result of intensive studies to achieve the above object, the inventors found that if a specific polymer is selected and used as the thermoplastic polymer for forming the polymer coating layer, high-density printing without character loss or fading can be achieved. In addition, the durability of the coating layer is significantly improved, and the problem of capri of printed matter due to an increase in the number of prints is avoided, and a higher quality heat-sensitive stencil paper that satisfies both printing sensitivity and stiffness resistance is obtained. After realizing that it was possible to achieve this goal, he completed this invention.

That is, this invention provides a heat-sensitive stencil layer on one surface of a porous thin sheet material, in which a polymer mainly composed of a copolymer of an olefin monomer and an acrylic monomer (hereinafter referred to as an olefin-acrylic copolymer) is used. This invention relates to a heat-sensitive stencil paper characterized by being provided with a coating layer.

[Structure and operation of the invention]

Porous thin leaf materials used in this invention include natural fibers such as manila hemp, kozo, and mitsumata, synthetic fibers such as polyester and nylon, and nonwoven fabrics made by mixing these with a basis weight of 5 to 15 glrd; Or polyester fiber.

Silk screen gauze etc. can be used.

The olefin-acrylic copolymer used in this invention is obtained by copolymerizing an olefin monomer and an acrylic monomer by various known methods, and the above copolymerization may be random type, block type, The 0 molecular weight, which may be any of the graft types, has an average molecular weight of 20.000 to 50.
A value in the range of 0.0000 is particularly preferable in terms of sensitivity and printing durability of the base paper finally obtained.

The above olefinic monomers include ethylene, propylene, butene, hexene, pentene, methylhexene,
Examples of acrylic monomers include methylpentene, and examples of acrylic monomers include the following formula;% formula% (wherein, R1 is hydrogen or a methyl group, and R2 is
Alkyl esters of acrylic acid or methacrylic acid represented by (1O alkyl group), such as methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, etc. . Of course, the present invention is not limited to these monomers, and various known olefinic and acrylic monomers can be used.

As for the copolymerization ratio of both vehicle bodies mentioned above, the proportion of acrylic monomer in the total amount of both vehicle bodies is 5 to 50% by weight.
The content of the acrylic monomer is particularly preferably 10 to 40% by weight. Too little of the acrylic monomer lowers rigidity resistance, and too much of the acrylic monomer impairs printing sensitivity, which is not preferred.

In addition, in this invention, in addition to the above-mentioned olefin-acrylic copolymer, one or more other thermoplastic polymers such as ethylene-vinyl acetate copolymer, butyral resin, and acrylic resin may be used in combination. You can also do that. However, in this case, it is desirable that the amount of the other thermoplastic polymers is suppressed to 20% by weight or less of the total weight.

In addition, in this invention, the above-mentioned olefin-acrylic copolymer is provided as a coating layer on one surface of the porous thin sheet material, and at this time, antioxidants, lubricants,
Various additives such as plasticizers and antistatic agents may be included as necessary, and the content of these additives is 50% by weight or less of the entire coating layer. In other words, the coating layer may not only consist of the olefin-acrylic copolymer alone, but may also consist of the olefin-acrylic copolymer as a main component and an appropriate amount of the above-mentioned additives.

Various methods can be considered for forming a heat-sensitive stencil layer consisting of such a coating layer. However, since the olefin-acrylic copolymer is a polymer that is soluble at 25°C in an amount of at least 1% by weight in an organic solvent that is not compatible with water, 1% by weight of this olefin-acrylic copolymer is dissolved in the above organic solvent.
It is most preferable to adopt the method described below using the above-dissolved solution. According to this method, the olefin-acrylic copolymer penetrates into the porous thin material and the coating layer has a coating film such as fish eyes. This is because a thin and uniform coating layer can be easily formed without causing defects.

This preferred method includes a step of sufficiently filling the voids of the porous thin sheet material with water, and applying an organic solvent that is incompatible with water to one side of the water-containing porous thin sheet material and an olefin dissolved therein in an amount of 1% by weight or more. - A method consisting of a step of applying a solution containing an acrylic copolymer and, if necessary, other thermoplastic polymers and additives mentioned above, and a step of drying after this application to sequentially remove the above-mentioned organic solvent and water. It is.

In this way, when a porous thin sheet material is filled with water and then a solution of an olefin-acrylic copolymer dissolved in an organic solvent that is incompatible with water is applied, the voids in the porous thin sheet material are filled with water. Therefore, the applied solution forms a layer without penetrating into the voids, and by drying it, an extremely thin layer of 2 μm or less, usually 0.1 to 1.5 μm, is formed on the surface of the porous thin sheet material. It is possible to form a uniform polymer coating layer without coating defects such as fish eyes. Moreover, the surface of the porous thin sheet material and the polymer coating layer are physically and chemically bonded at the interface by selecting and using porous thin sheet materials and olefin-acrylic copolymers that have good affinity for each other. This creates a strong bond.

In the above method, the filling of water into the porous thin film material is
This can be done by various methods such as roll coating and dipping, and the polymer solution can be applied by applicator coating, fountain coating, goo coating, and the like. These methods themselves are not particularly limited.

Organic solvents that are incompatible with water include hexane, cyclohexane, cyclohexene, benzene, toluene, xylene, chloroform, ethyl acetate, methyl ethyl ketone,
Many organic solvents may be mentioned, such as methyl isobutyl ketone. The olefin-acrylic copolymer is dissolved in one or more of these organic solvents, and if necessary, the other thermoplastic polymers and additives mentioned above are added, but the polymer concentration at this time is at least 1% by weight. , usually 2-1
In order to form a thin and uniform coating layer, it is desirable to have a weight of 0% weight.

Drying conditions after application vary depending on the type of organic solvent, but
Normally, the heating time may be about 1 to 10 minutes at 60 to 100°C. By this drying, first, the organic solvent in the coating layer is volatilized, and then the water filled in the porous thin sheet material is volatilized and removed.

In addition to the methods described above, methods for forming the coating layer include, for example, directly melt-coating an olefin-acrylic copolymer onto one surface of a porous thin sheet material, and coating a solution of an olefin-acrylic copolymer on a release paper. There is also a method of thermally transferring this to one surface of a porous thin sheet material without using an adhesive. However, in these cases, the conditions for melt coating and thermal transfer must be set appropriately to prevent the olefin-acrylic copolymer from penetrating into the porous thin material and to prevent coating defects such as fish eyes from occurring in the coating layer. should be selected.

The heat-sensitive stencil paper of this invention obtained in this way is
If necessary, a release layer for preventing adhesion during plate making and an anti-sticking layer for preventing sticking with a thermal head may be provided on the surface of the polymer coating layer as a heat-sensitive stencil layer.

Plate making and printing using the heat-sensitive stencil paper of the present invention may be carried out according to conventional methods. For example, plate making can be done by placing an offset printing original on the surface of a heat-sensitive stencil layer and perforating it with heat using a commercially available heat-sensitive stencil maker, and for printing, using a commercially available stencil printing machine, the base paper after the stencil printing is transferred to an ink drum. It is sufficient to wrap the material around the porous thin sheet material and print while supplying ink from the porous thin material side.

〔Effect of the invention〕

The heat-sensitive stencil paper of the present invention has a heat-sensitive stencil layer formed by providing a coating layer mainly composed of an olefin-acrylic copolymer on one side of a porous thin material.
Not only does it provide the same advantages as the previous invention, such as higher quality printing due to the thinner heat-sensitive stencil layer, but it also has particularly good printing sensitivity and can perform high-density printing without missing or blurring characters. The durability of the polymer coating layer is improved, the rigidity resistance is improved, and the special effect of preventing fogging of printed matter due to an increase in the number of printed sheets can be achieved.

〔Example〕

EXAMPLES Below, examples of the present invention will be described in more detail.

Example 1 A porous tissue paper made of Manila hemp with a basis weight of 9 g/rd was filled with water by a dipping method, and then the surface was coated with 2 ethylene-ethyl acrylate copolymer (ethyl acrylate content: 25% by weight). A wt% toluene solution was applied using an applicator with a slit thickness of 50 μm, and then
Dry at 0°C for 1 minute to form a heat-sensitive stencil layer of approximately 1 μm.
A heat-sensitive stencil paper having a thick coating layer made of ethylene-ethyl acrylate copolymer was obtained. 0.1 g of silicone oil was applied as a release layer to the coated layer surface of this heat-sensitive stencil paper.
Wire barcoding was performed to obtain 1 cd.

Example 2 2% by weight of propylene-methyl acrylate copolymer (containing methyl acrylate 1E30%) as a polymer solution
A heat-sensitive stencil paper was prepared in the same manner as in Example 1, except that a toluene solution was used, the drying conditions after coating were 100°C for 1 minute, and the dry thickness was approximately 1 μm. A silicone coat was applied.

Comparative Example 1 Nitrocellulose (nitrogen content 12
A 2% by weight methyl isobutyl ketone solution with an average molecular weight of 23.000 was used, and the drying conditions after application were set to 10% by weight.
A heat-sensitive stencil paper was prepared in the same manner as in Example 1, except that the temperature was 0''C for 1 minute and the dry thickness was approximately 1 μm, and the same silicone coating as in Example 1 was applied.

Comparative Example 2 A 2% by weight cyclohexene solution of polymethylpentene resin (melt index 26, density 0.835) was used as a polymer solution, and the drying conditions after application were 80°C for 1 minute, and the dry thickness was approximately 1 μm. Except for this, a heat-sensitive stencil paper was prepared in the same manner as in Example 1, and the same silicone coating as in Example 1 was applied.

Regarding the heat-sensitive stencil paper of the above Examples and Comparative Examples, in order to examine the printing sensitivity and stiffness resistance, an offset printing original was placed on the coated layer surface of each base paper, and a heat-sensitive stencil maker (trade name manufactured by Riso Kagaku Kogyo Co., Ltd. A plate was made using a normal manuscript scale of 1 using a lithographic printer (FX7200), and then printing was performed using a stencil printing machine (trade name: AP7200, manufactured by Riso Kagaku Kogyo Co., Ltd.).

As a result, in the base paper of Comparative Example 1, the character density was slightly thinner, and there were some characters missing and fading, and in the base paper of Comparative Example 2, capri occurred on the printed matter when the number of copies exceeded 10, but in Example 1, With the base paper No. 2, very high density printing was possible with no missing or blurred characters, and no fogging was observed on the printed matter even when the number of printed sheets exceeded 50. From these results, it is clear that the heat-sensitive stencil paper of the present invention has excellent printing sensitivity and stiffness resistance.

Claims (1)

[Claims] (1) A heat-sensitive stencil paper characterized in that a polymer coating layer mainly composed of a copolymer of an olefin monomer and an acrylic monomer is provided as a heat-sensitive stencil layer on one side of a porous thin sheet material. . (2) The acrylic monomer is represented by the following formula; ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R_1 is hydrogen or a methyl group, and R_2 is an alkyl group having 1 to 10 carbon atoms.) The heat-sensitive stencil paper according to claim (1), which is an alkyl ester of acrylic acid or methacrylic acid.