JPH01114478A - Pressure-sensitive copying paper - Google Patents

Abstract

PURPOSE:To improve an initial color-forming ability and to prevent deterioration of a developed color image, by coating a support with a coating solution containing an organic developer and triphenyl phosphate to thereby prepare a pressure-sensitive copying paper having a developer layer. CONSTITUTION:An organic developer is treated with an agitator-pulverizer to form an aqueous dispersion or a solution in an organic solvent, and then emulsified in water with the aid of an emulsifying and dispersing agent such as polyvinyl alcohol, followed by distillation to remove the organic solvent. At this time also triphenyl phosphate is added to the remaining solution to prepare a mixed coating solution. This solution is applied on a support and dried to form a developer layer, thus preparing a pressure-sensitive copying paper. Examples of the organic developer include aromatic carboxylic acids, such as benzoic and salicylic acids, and their salts. Preferably about 0.2-100pts. wt. triphenyl phosphate is used per 100pts.wt. organic developer.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to pressure-sensitive copying paper using an organic coloring agent.1. In particular, the present invention relates to pressure-sensitive copying paper that provides a high-density color image immediately after printing.

``Prior Art'' Pressure-sensitive copying paper uses a color-forming agent capsule composition, which is mainly composed of microcapsules containing an oil-based substance in which an electron-donating organic coloring agent (hereinafter simply referred to as coloring agent) is dissolved, as a support. The upper paper is coated on one side, and a coloring agent composition containing an electron-accepting coloring agent (hereinafter simply referred to as coloring agent) as a main component that changes color when it comes into contact with the coloring agent is applied to one side of the support. There are various types of sheets, such as an inner sheet coated with a color former capsule composition on the opposite side, and a lower sheet coated with a color former composition on one side of the support. They are put into practical use as a copy set by combining them in the order of paper - bottom paper. Also known is a self-coloring type pressure-sensitive copying paper which allows pressure-sensitive recording on a single sheet by coating a coloring agent and a coloring agent on the same side of a support.

Coloring agents for such pressure-sensitive copying paper include inorganic coloring agents such as acid clay, activated clay, acpulgite, zeolite, bentonite, silica, aluminum silicate, and fesol aldehyde polymers and phenol-acetylene. Organic coloring agents such as phenol polymers such as polymers, polyvalent metal salts of aromatic carboxylic acids or derivatives thereof are known.

Among these, organic coloring agents have a higher coloring ability than inorganic coloring agents, and have the advantage that the color image obtained does not lose its density due to moisture adhesion or normal file storage.

However, the disadvantage is that the color density immediately after printing is low and it takes time to reach saturation density (so-called disadvantage of poor initial color development).
There is a need for improvement.

Conventionally, as a method to overcome this drawback, a method has been used to reduce the viscosity of an oily substance that dissolves the color former to accelerate the contact between the color former and the color former. However, because the viscosity of the oily substance increases especially under low temperature conditions, it is currently not possible to obtain satisfactory results with this method.

``Problems to be Solved by the Invention'' In view of the current situation, as a result of intensive research on methods for improving the above-mentioned drawbacks associated with organic coloring agents, it was found that when a specific phosphoric acid ester is used in combination with an organic coloring agent, It was discovered that the initial color development was significantly improved, and the present invention was completed.

"Means for Solving the Problem" The present invention is a pressure-sensitive copying paper characterized by having a coloring agent layer containing an organic coloring agent and triphenyl phosphate.

"Function" In the pressure-sensitive copying paper of the present invention, triphenyl phosphate, among various phosphoric esters, is selectively used in combination with an organic coloring agent.

As phosphate esters other than triphenylphosphate,
For example, tributyl phosphate, tri-2-ethylhexyl phosphate, tributoxyethyl phosphate, tris-chloroethyl phosphate, tris-dichloropropyl phosphate, tricresyl phosphate, tricylenyl phosphate, cresyl diphenyl phosphate, Xylenyl diphenyl phosphate, 2-ethylhexyl diphenyl phosphate, trilauryl phosphate, tricetyl phosphate, tristearyl phosphate, trioleyl phosphate, tris(tribromophenyl) phosphate, etc., and most of them are It has the effect of improving initial color development. However, in most of the pressure-sensitive copying papers obtained by using these phosphate esters in combination, a phenomenon is observed in which the color images are significantly deteriorated by light. However, when tributyl phosphate is used in combination, the initial color development is improved without deterioration of the color image due to light, but since tributyl phosphate is liquid at room temperature, the surface of the color former layer is It is sticky and may cause trouble during printing.

Triphenylphosphate, which is particularly selectively used in the present invention, is an initial material for pressure-sensitive copying paper that can be obtained extremely efficiently without new drawbacks such as deterioration of colored images due to light or stickiness on the surface of the coloring agent layer. This improves coloring performance. Although the reason for this effect is not necessarily clear,
It is presumed that the above compound improves adsorption and compatibility between the oil-based substance containing the color former and the organic color former, resulting in pressure-sensitive copying paper with extremely excellent initial color development ability. .

As an organic coloring agent, for example, Japanese Patent Publication No. 49-10856
No., Special Publication No. 51-25174, Japanese Patent Publication No. 49-5541
Benzoic acid, p-tert as described in No. 0 etc.
-butyl-benzoic acid, 4-methyl-3-nitrobenzoic acid, salicylic acid, 3-phenylsalicylic acid, 3-cyclohexylsalicylic acid, 3-tert-butyl-5-methylsalicylic acid, 3゜5-di-tert-butylsalicylic acid, 3-Methyl-5-benzylsalicylic acid, 3-phenyl-5-(α,α-dimethylbenzyl)salicylic acid, 3-
Cyclohexyl-5-(α,α-dimethylbenzyl)salicylic acid, 3-(α,α-dimethylbenzyl)-5-methylsalicylic acid, 3.5-di-cyclohexylsalicylic acid, 3.5-di(α-methyl benzyl) salicylic acid,
3.5-di(α,α-dimethylbenzyl)salicylic acid, 3-(α-methylbenzyl)-5-(α,α-dimethylbenzyl)salicylic acid, 4-methyl-5-cyclohexylsalicylic acid, 2-hydroxy -1-benzyl-3-
Naphthoic acid, 1-benzoyl-2-hydroxy-3-naphthoic acid, 3-hydroxy-5-cyclohexyl-2-
Aromatic carboxylic acids such as naphthoic acid, 2-hydroxy-4-[(4-carboxy-5-hydroxy)phenyl]-1-naphthoic acid, and polyvalent metals such as zinc, aluminum, magnesium, calcium, and cobalt. Salt with; Special Publication No. 1977-9309, Special Publication No. 42-2014
Phenol compounds such as 6,6°-methylenebis(4-chloro-m-cresol) as described in No. 4, JP-A-48-14409, etc.; Phenol-aldehydes such as p-phenylphenol-formaldehyde resin; resins, phenolic resins such as phenol-acetylene resins such as p-tert-butylphenol-acetylene resins, and polyvalent metal salts thereof; maleic acid-rosin resins, copolymers of styrene, ethylene or vinyl methyl ether and maleic anhydride. Acidic polymers such as;
-8215, Special Publication No. 1972-8216, Special Publication No. 1972-
Polymers of aromatic carboxylic acids and aldehydes or acetylene and polyvalent metal salts thereof, etc., as described in JP-A-62-19486; Examples include modified terpene phenol resins.

Among these organic coloring agents, aromatic carboxylic acids and polyvalent metal salts thereof are particularly preferably used because they have excellent desired effects.

A coloring agent layer containing an organic coloring agent and triphenyl phosphate is generally prepared by preparing a coating liquid containing both of them and applying it to a support.

At that time, the method for preparing the coating liquid is not particularly limited, and may be prepared according to an appropriate conventional method. That is, organic coloring agents are usually treated with a stirring grinder such as a sand mill, ball mill, or attritor to form an aqueous dispersion, or dissolved in an organic solvent and then emulsified in water with an emulsifying/dispersing agent such as polyvinyl alcohol. Later, the organic solvent is distilled off and used, and a mixed coating liquid can be easily prepared by using triphenyl phosphate in combination. The amount of triphenylphosphate used in combination with the organic coloring agent is 0.2 to 100 parts by weight of the organic coloring agent.
It is desirable to adjust the amount to about 100 parts by weight, more preferably from 1 to 20 parts by weight.

The coating solution usually contains adhesives such as starch, casein, gum arabic, carboxymethyl cellulose, polyvinyl alcohol, styrene-butadiene copolymer latex, vinyl acetate latex, etc. In addition, zinc oxide, magnesium oxide, Inorganic pigments such as titanium oxide, aluminum hydroxide, calcium carbonate, magnesium sulfate, and calcium sulfate, as well as various auxiliaries known in the field of pressure-sensitive copying paper manufacturing, may be added as appropriate.

The color former coating solution thus prepared is coated onto a support using a conventional coating device such as an air knife coater, blade coater, roll coater, size press coater, curtain coater, short dwell coater, etc., and then coated on a pressure-sensitive copying paper. Finished as colored paper.

The present invention is directed to a self-coloring pressure-sensitive material having a coloring agent layer and a coloring agent layer on the same side of a support, or having a mixed coating layer of a coloring agent coating liquid and a coating liquid containing an encapsulated coloring agent. It can also be applied to copy paper (so-called self-contained type).

"Examples" Examples and comparative examples will be described below to further clarify the effects of the present invention, but the present invention is not limited thereto. Furthermore, "parts" and "%" in the examples represent "parts by weight" and "% by weight", respectively, unless otherwise specified.

Example 1 [Preparation of color former coating liquid] 3.5-di(α-methylbenzyl)zinc salicylate 1
00 parts and 5 parts of triphenylphosbate in 10 parts of toluene.
0 parts of 3% polyvinyl alcohol aqueous solution 15
0 parts using a homomixer, and then toluene was distilled off to obtain an aqueous dispersion of coloring agent fine particles. This aqueous dispersion contains 700 parts of calcium carbonate and 10 parts of aluminum hydroxide.
Water was added to a dispersion obtained by mixing 0 parts of zinc oxide, 100 parts of zinc oxide, 200 parts of a 25% aqueous solution of oxidized modified starch, and 208 parts of styrene-butadiene latex (48% dispersion) to give a solid content concentration of 25%. A coloring agent coating solution was prepared.

[Manufacture of colored paper for pressure-sensitive copying paper]

The above coloring agent coating liquid was coated on one side of a 40g/rrf base paper so that the dry weight was 5g/n (dry weight), and dried to obtain a colored paper for pressure-sensitive copying paper.

Comparative Example 1 Except that an aqueous dispersion obtained by processing 400 parts of a 25% aqueous dispersion of zinc 3.5-di(α-methylbenzyl)salicylate in a sand mill was used as an aqueous dispersion of colorant fine particles. A colored paper for pressure-sensitive copying paper was obtained in the same manner as in Example 1.

Comparative Example 2 A colored paper for pressure-sensitive copying paper was obtained in the same manner as in Example 1, except that tris-dichloropropyl phosphate was used instead of triphenyl phosphate.

Comparative Example 3 A colored paper for pressure-sensitive copying paper was obtained in the same manner as in Example 1 except that tributyl phosphate was used instead of triphenyl phosphate.

The four types of colored paper thus obtained were subjected to the following quality evaluation tests, and the results are shown in Table 1.

[Creation of top paper]

A capsule coating liquid prepared by dissolving crystal violet lactone in alkylated naphthalene and microcapsulating this oily liquid was applied to one side of base paper at a dry weight of 4 g/rr.
It was coated so that the color was r and dried to obtain a top paper.

In autumn, the colored paper and the top paper were left in an atmosphere at 0°C for 1 hour. Next, the coated surfaces of the colored paper and top paper were placed facing each other, and in an atmosphere of 0°C, they were tested using a drop type coloring tester (weight: 150g, height: 20°C).
cm), and the color density was measured using a Macbeth reflection densitometer 10 seconds after the impact and 1 day later.

Layer the top paper and bottom paper so that the coated surfaces face each other, apply a load of 100 kg/ca to form a colored image, measure the color density with a Macbeth color densitometer, and calculate the value as Do. Next, after irradiating the colored image with ultraviolet rays from a distance of 20 cm, the color density was measured and the value was expressed as:

Light resistance is defined by the following formula, and the closer the value is to 100, the better the light resistance.

D.

The surface of the coloring agent layer was printed using an R1 printing tester (manufactured by Mei Seisakusho), and its surface strength was evaluated using the following evaluation criteria.

○...Good △...Slightly poor Table 1 "Effects of the Invention" As is clear from the results in Table 1, the colored paper for pressure-sensitive copying paper obtained in the Examples of the present invention has no color image. It exhibited excellent initial coloring ability without deterioration due to light irradiation or decrease in strength of the coloring layer surface.

Claims (1)

[Claims] A pressure-sensitive copying paper characterized by having a color former layer containing an organic color former and triphenyl phosphate.