JPH0327977A - Paint composition for pressure-sensitive copy paper - Google Patents

Abstract

PURPOSE:To obtain a paint composition for pressure-sensitive copy paper excellent in pressure-resistant anti-staining properties, color developability, adhesiveness and flux resistance by constituting a binder of a specific amount of an unsaturated nitrile monomer, an aliphatic conjugated diene monomer and an ethylenic unsaturated carboxylic acid monomer. CONSTITUTION:A binder is constituted of 10-50wt.% of an unsaturated nitrile monomer, 35-80wt.% of an aliphatic conjugated diene monomer and 0.5-20wt.% of an ethylenic unsaturated carboxylic acid monomer. As the unsaturated nitrile monomer, acrylonitrile and methacrylonitrile are designated and, as the aliphatic conjugated diene monomer, butadiene, 2-methyl-1,3-butadiene and halogen substituted butadiene are designated. As the ethylenic unsaturated carboxylic acid monomer, acrylic acid, methacrylic acid and maleic acid are designated. By this constitution, a paint composition for pressure-sensitive copy paper excellent in pressure-resistant anti-staining properties, color developability, adhesiveness and flux resistance is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Field of Application> The present invention relates to a sacred material composition for pressure-sensitive copying paper that is excellent in pressure stain resistance, color development, adhesiveness and solvent resistance.

<Prior art> In general, pressure-sensitive copying paper is produced by coating a base paper with a coating liquid mainly consisting of microcapsules containing an oil in which an electron-donating colorless dye is dissolved and a coating liquid mainly consisting of an electron-accepting color developer. Manufactured by

The forms of pressure-sensitive copying paper include top sheet paper coated with microcapsules, bottom sheet paper coated with a color developer, and middle sheet paper coated with microcapsules on one side and a color developer on the other side.
Create a set of pressure-sensitive copying paper by stacking the top and bottom sheets with their coated sides facing each other, or by inserting one or more sheets of middle paper between the top and bottom sheets, and then use a typewriter. When pressure is applied by writing, etc., the microcapsules are destroyed, and the oil containing the colorless dye flows out and is transferred to the developer surface.
Develops color. It also includes a so-called single recording sheet in which microcapsules and a color developer are coated on the same side of the sheet as another form.

Conventionally, microcapsules for pressure-sensitive copying paper have been manufactured mainly by the coacervation method using gelatin, but only low-concentration capsules can be obtained, and the process is not only complicated, but also has problems with stability and spoilage. In recent years, interfacial polymerization methods (such as British Patent No. 1046409) using polyamide, polyurethane, Polylya, saturated polyester, etc. as membrane materials have been developed. In-situ method using melamine-formaldehyde resin or urea-formaldehyde resin as a membrane material (Japanese Patent Publication No. 46-802)
Microcapsules obtained by methods such as 82) have been put into practical use. Microcapsules using synthetic resin as membrane material can be produced in a considerably simpler manufacturing process than gelatin-based capsules, and can yield highly concentrated slurry.

In addition, it has excellent water resistance and chemical resistance, and does not spoil even if the capsule is stored in a slurry state for a long time, and has many advantages not found in gelatin capsules.

However, when microcapsules made of synthetic resin membrane material are used in pressure-sensitive copying paper, they have the disadvantage that they tend to stain more easily than gelatin capsules due to contact and friction during handling and processing. In order to improve this drawback, various studies have been made from the viewpoint of binders.

Furthermore, the fields in which pressure-sensitive paper is used are expanding year by year, and new problems have arisen accordingly.

For example, in the case of slip books used at gas stations, if the slips are handled with hands covered with gasoline, the solvent will destroy the microcapsules, causing color stains, and even impeding the color development itself. It turns out.

Therefore, in order to solve these problems, it is desired that capsule-coated paper with excellent solvent resistance be developed.

<Problems to be Solved by the Invention> The present invention solves the above-mentioned problems in pressure-sensitive copying paper using microcapsules made of synthetic resin as a film material, namely pressure stain resistance and solvent resistance, and also improves color development. An object of the present invention is to provide a coating composition for obtaining pressure-sensitive copying paper with excellent properties and adhesion.

<Means for Solving the Problems> The present inventors have proposed a coating composition for pressure-sensitive copying paper containing microcapsules and a binder whose film material is a synthetic resin, in which a copolymer having a specific composition is used as the binder. The inventors have discovered that the object can be achieved by using a combined latex, and have completed the present invention.

That is, the present invention provides a coating composition for pressure-sensitive copying paper containing microcapsules made of a synthetic resin as a membrane material and a binder, in which the binder includes 10 to 50% by weight of an unsaturated nitrile monomer, an aliphatic conjugate Diene monomer 35
~80% by weight, 0.0% ethylenically unsaturated carboxylic acid monomer.
The object of the present invention is to provide a coating material for pressure-sensitive copying paper which is characterized by having a content of 5 to 20% by weight and is excellent in pressure stain resistance, color development, adhesiveness, and solvent resistance.

Hereinafter, the present invention will be explained in detail.

Examples of the unsaturated nitrile monomer constituting the copolymer latex in the present invention include acrinitrile, methacrylonitrile, etc., and one or more of them can be used. Acrylonitrile is particularly preferred.

If the content of the unsaturated nitrile monomer is less than 10% by weight, color development and pressure stain resistance will be poor, and if it exceeds 50ffii%, adhesiveness will be poor, which is not preferred. Preferably 15-45% by weight
It is.

Examples of the aliphatic conjugated diolefin monomers include butadiene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, halogen-substituted butadiene, and one or more of them. Can be used. Particularly preferred is butadiene.

If the aliphatic conjugated diolefin monomer is less than 35% by weight, the adhesion and pressure stain resistance will be poor, and if it exceeds 80% by weight, the color development will be insufficient, preferably 40 to 75% by weight.
It is.

Examples of the ethylenically unsaturated carboxylic acid monomer include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, fumaric acid, maleic acid, etc., and one type or two or more types can be used. Particularly preferred are acrylic acid, methacrylic acid and itaconic acid.

If the content of the ethylenically unsaturated carboxylic acid monomer is less than 0.5% by weight, the adhesion and pressure stain resistance will be poor, and if it exceeds 20% by weight, the viscosity of the copolymer latex will increase and the workability will be poor, which is undesirable. Preferably it is 1 to 15% by weight. The average particle diameter and gel content in the copolymer latex of the present invention are not particularly limited, but each is 1200 to 15% by weight.
Preferably, it is 250OA and 90% by weight or less.

Furthermore, regarding the manufacturing method of the copolymer latex, for example, known emulsion polymerization methods such as continuous emulsion polymerization, bulk emulsion polymerization, and two-stage emulsion polymerization can be adopted. Additives and auxiliaries used in general emulsion polymerization, such as initiators, electrolytes, and chelating agents, can be used, and the polymerization temperature can be selected from either high or low temperatures.

The average particle diameter and gel content of the copolymer latex can be generally adjusted by appropriately selecting the amounts of the emulsifier and chain transfer agent used during emulsion polymerization.

The microcapsules in the present invention are those whose membrane material is synthetic resin, and the microcapsules can be produced by interfacial polymerization method using polyamide, polyurethane, polyurea, etc. as membrane material, or by in-line polymerization method using urea-formaldehyde or melamine-formaldehyde resin as membrane material. - Manufactured by in situ method etc.

The amount of copolymer latex used is not particularly limited, but it is preferably 5 to 40 parts by weight, more preferably 10 to 30 parts by weight per 100 parts of microcapsules.

In addition, the coating composition of the present invention may optionally contain polyvinyl alcohol, starch, dextrin, a water-soluble binder such as carboxymethyl cellulose, hydroxyethyl cellulose, and casein, a capsule protectant such as cellulose powder, starch particles, and talc, and other antifoaming agents. Various auxiliary agents such as a water-proofing agent, a UV absorber, a basic pigment, etc. can be appropriately blended.

<Examples> The present invention will be specifically explained below with reference to Examples, but the present invention is not limited to the Examples in any way. In addition,
All parts and percentages used refer to parts and percentages by weight unless otherwise specified.

In addition, the test methods for various measurement items are as follows.

(a) Color development The microcapsule-coated paper prepared in the Examples and Comparative Examples of the present invention and the bottom sheet of commercially available pressure-sensitive copying paper were stacked, printed using an electric typewriter, and the color density was visually observed after 5 minutes. Judgment was made.

(bJ Severe pressure contamination) After overlapping the microcapsule-coated paper prepared in the Examples and Comparative Examples of the present invention with the bottom sheet of commercially available pressure-sensitive copying paper, pressure was applied using an RI printing machine, and the contamination state of the bottom sheet was was determined visually.

Cutting Adhesion 1) RI Wet Pick Strength The degree of picking when printed using dampening water on an RI printing machine was visually judged. Grade 1 (5 from the best)
(Assessed on a five-point scale, with the worst being the worst.)

1) RI Dry Pick Strength Evaluation was performed in the same manner as the RX wet pick strength measurement method described above, except that no dampening water was used.

(Solvent Resistance) Ligroin was injected into the bottom of the co-desiccator in advance, and the microcapsule-coated papers prepared in the Examples and Comparative Examples of the present invention were set in the co-desiccator and left in the ligroin atmosphere for two days. The coated paper was evaluated in the same manner as (a) coloring property and (return pressure staining property) described above.

Preparation of copolymer latex In an autoclave that had been purged with nitrogen in advance, add the monomer mixture shown in Table 1, t-dodecylmercabutane, sodium alkylbenzenesulfonate, 0.5 part of sodium bicarbonate, and 1 part of potassium persulfate. 0 parts and 100 parts of pure water were added, and polymerization was carried out at 70°C for 16 hours with stirring to obtain a copolymer latex.

Preparation of microcapsules of polyvinylbenzenesulfonic acid adjusted to pH 4
% aqueous solution, 4 parts of crystal violet lactone was added to an organic solution (KMC-113-10 manufactured by Kureha Chemical Co., Ltd.).
A color former oil was dissolved in 0 parts and emulsified and dispersed to obtain an O/W type emulsion. To this was added 12.5 parts of 80% melamine formalin initial condensate (manufactured by Sumitomo Chemical Co., Ltd.: SR-613), and after polymerization at 60°C for 2 hours, plating with NaOH
The temperature was adjusted to 7 to 8 to prepare a microcapsule dispersion.

Examples 1 to 5 and Comparative Examples 1 to 5 Solid content of microcapsule dispersion prepared by the above method: 1
00 parts, add 30 parts solid content of copolymer latex shown in Table 1 and 30 parts wheat starch,
After adjusting the pH to 8 with sodium hydroxide, the solid content was adjusted to 20%.
% and apply 4.0P/m on the base paper using a wire bar.
A microcapsule-coated paper was prepared by applying the following. Color development using this microcapsule coated paper,
Pressure stain resistance, adhesion and solvent resistance were investigated.

<Effects of the Invention> As described above, by using the coating composition of the present invention, microcapsule-coated paper for pressure-sensitive copying paper with excellent pressure stain resistance, color development, adhesiveness, and solvent resistance can be obtained. It is something that can be done.

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Claims (1)

[Claims] 1. A coating composition for pressure-sensitive copying paper containing microcapsules made of a synthetic resin as a film material and a binder, in which the binder contains 10 to 50% by weight of an unsaturated nitrile monomer and an aliphatic conjugated diene monomer. 1. A coating composition for pressure-sensitive copying paper, comprising 15 to 80% by weight of an ethylenically unsaturated carboxylic acid monomer and 0.5 to 20% by weight of an ethylenically unsaturated carboxylic acid monomer.