JPH0726184A - Developer ink and method for producing the same - Google Patents

Abstract

(57) [Summary] [Purpose] A color-developing ink using an organic color developer having excellent color-forming property, yellowing property, image storability, printability, and good ink-forming workability, and a method for producing the same. [Structure] An organic developer is synthesized in a low-boiling-point solvent, an ink solvent is added to the organic-developing agent, and then the low-boiling-point solvent is distilled off to obtain an organic developer solution. A method for producing a color-developing ink in which ink components other than a solution are mixed or compatible, and kneaded to form an ink, and a color-developed ink.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color developing ink and a method for producing the same. More specifically, it relates to a color-developing ink for carbonless copying paper which can react with a colorless or light-colored electron-donating dye (hereinafter referred to as a color former) to obtain a colored image, and a method for producing the same.

[0002]

2. Description of the Related Art Generally, a carbonless copying paper is an upper paper having microcapsules containing oil in which a color former is dissolved coated on the back surface of a base paper, and an electron-accepting solid acid (hereinafter referred to as a developer). ) Is coated on the surface of the base paper, and these two kinds of coating layers are superposed so as to face each other, and mechanical pressure of a ball-point pen or a typewriter, etc.
The microcapsules in the pressurized portion are destroyed, and the oil in which the color-developing agent is dissolved is transferred to the color-developing agent layer to develop color, so that a record of simultaneous copying can be obtained. It should be noted that a plurality of simultaneous copying records can be obtained by using the middle paper which also serves as the upper paper and the lower paper. These carbonless copying papers are mainly used as office papers for copying.

In general, since the developer layer of the lower or middle paper is coated on the entire surface of the paper, it is necessary to print a desensitizing ink on the portion where the coloring of the copy is not desired to prevent the coloring. It was very uneconomical. For this reason, conventionally, a method of spot-printing a color-developing ink on the surface of an upper sheet or on a plain sheet only on a portion that requires color development for copying to form a middle sheet and a lower sheet has been used.

Most of the color-developing inks that have been put into practical use are those for flexographic printing using a low-boiling organic solvent, but there are safety or hygiene problems such as flammability, explosiveness, and poisoning. Had. On the other hand, JP-A Nos. 51-68307, 51-80410 and 51
-94308, 54-98816, 54-94
No. 910, No. 54-148606, No. 55-3882.
No. 6, No. 55-38826, No. 59-33369 and the like disclose color-developing inks for letterpress or offset printing, and UV-curable color-developing inks are also partially used. Has been done.

Conventionally, a phenol resin, a salicylic acid derivative or a polyvalent metal salt thereof is known as a developer for a flexographic, letterpress or offset developer ink.
Examples of the phenol resin include p-phenylphenol formaldehyde resin, p-cumylphenol formaldehyde resin, p-butylphenol formaldehyde resin, p-octylphenol formaldehyde resin and the like.

Examples of salicylic acid derivatives or polyvalent metal salts thereof include 3,5-di-tert-butylsalicylic acid and 3,5-di-tert-butylsalicylic acid.
5-di- (α-methylbenzyl) salicylic acid, 3-cyclohexyl-5- (α, α-dimethylbenzyl) salicylic acid, 3-phenyl-5- (α, α-dimethylbenzyl) salicylic acid, and the like, and calcium thereof. Examples thereof include polyvalent metal salts such as magnesium, aluminum, nickel, copper, zinc, tin and barium. Generally, a zinc salt is used. Further, JP-A-63-186729,
63-254124, 63-289017, 64-56724, 64-77575 and JP-A-1.
-133780, 1-182317, 2-16
The salicylic acid resin polyvalent metal salts disclosed in each publication such as No. 0815 and No. 4-89274 can also be mentioned as useful organic developers.

When making these organic developers into inks, it is necessary to heat and dissolve the organic developers using a suitable ink solvent. However, the above-mentioned organic color developer is difficult to dissolve, and particularly the polyvalent metal salt of salicylic acid derivative is difficult to dissolve. This is because it is necessary to select and use a solvent that does not damage rubber rolls, printing materials, blankets, etc. used in printing machines as an ink solvent, and these ink solvents have a very high ability to dissolve an organic developer. Because it is very low.
As described above, when these organic developers are dissolved in an ink solvent having a low dissolving ability to form an ink, the dissolution time is long,
There are problems that the dissolution temperature is high, the undissolved portion of the organic developer is likely to remain, it is difficult to be compatible with other ink materials, and the workability for forming an ink is very poor.

In the case of a photo-curable color developing ink, the organic color developer is dissolved and diluted with an ink monomer, but when the solubility is poor, the dissolution time and the dissolution temperature are severe conditions for the monomer. However, there is an inconvenience that the polymerization proceeds to a part of the monomer. If there are not enough ink solvents to dissolve the organic color developer, poor workability for ink formation, polymerization of some of the ink monomers, etc., color development, yellowing, image storability, etc. Even if it has excellent performance as a developer, it is difficult to use it as a developer for developer ink, and it has excellent solubility, but it is inferior in properties such as color development. The current situation is that the
These problems are obstacles particularly when the polyvalent metal salt of salicylic acid derivative is used as an organic developer to form an ink, and improvement thereof is desired.

[0009]

DISCLOSURE OF THE INVENTION The present invention provides a method for producing a color-developing ink using an organic color developer, which has good workability for forming an ink, and thereby provides a color-forming property, a yellowing property, and an image. An object of the present invention is to provide a color-developing ink having excellent storage stability and suitability for letterpress printing or offset printing.

[0010]

Means for Solving the Problems As a result of intensive studies to solve these problems, the present inventors have synthesized an organic developer in a low boiling point solvent, and added and mixed an ink solvent to it. After that, in the organic developer solution obtained by distilling off the low-boiling-point solvent, an ink component other than the organic developer solution is mixed or compatible, and it is achieved by kneading to form an ink. I was able to. This method was particularly effective in the case of a photocurable developer ink using a photocurable compound as an ink solvent and an ink adhesive resin. or,
The color-developing inks produced by these production methods were able to obtain color-developing inks excellent in color developability, yellowing, and image storability by taking advantage of the characteristics of the organic color developer as a raw material.

The means for solving the problems will be described below in detail. In the production of the color-developing ink of the present invention, an organic color developer, an organic color developer solution consisting of a solvent for ink, and other components are used. As a component other than the organic color developer solution, an adhesive for ink is used. Agent resins, pigments and other additives are used. As the ink solvent or the ink adhesive resin, a photopolymerizable compound is also included. A typical example of the photo-curable developer ink is an ultraviolet ink, and an example of the present invention is an ultraviolet-curable developer ink.

As the organic developer, the above-mentioned phenol resin, salicylic acid derivative or polyvalent metal salt thereof can be used. In particular, since the salicylic acid derivative polyvalent metal salt is difficult to dissolve in the solvent for ink used for general ink, the production method according to the present invention is effective.

As the low boiling point solvent used in the polymerization of the organic developer, for example, n-hexane, n-heptane,
aliphatic hydrocarbons such as n-pentane and cyclohexane,
Ethers such as ethyl ether and ethylene glycol dimethyl ether, esters such as ethyl acetate and butyl acetate, methylene chloride, 1,2-dichloroethane, 1,1,
Halogenated hydrocarbons such as 2-trichloroethane, carbon tetrachloride, chloroform and monochlorobenzene, organic acids such as acetic acid and propionic acid, ketones such as acetone and methyl ethyl ketone, other benzene, toluene, xylene, carbon disulfide, nitromethane, Acetonitrile, tetrahydrofuran and the like can be mentioned, and a solvent inert to the reaction is selected and used.

As a method for polymerizing the organic color developer, a conventionally used method can be applied. For example, JP-A-49-
No. 37713, No. 64-56724, JP-A 1-13
The method described in each of the publications such as 3780, 2-653, and 4-129789 can be mentioned. By applying these methods, an organic developer in which an organic developer is dissolved in a low boiling point solvent is used. A colorant solution can be obtained. The solid content concentration of the organic developer during the polymerization reaction is not particularly limited, but the synthesis reaction is usually performed at a concentration of about 30 to 70% by weight.

In the present invention, as the ink solvent to be replaced with the low boiling point solvent used in the organic developer polymerization,
For example, high boiling point petroleum solvents having a boiling point of 200 ° C. or higher, higher fatty acid esters, higher alcohols, glycol solvents, linseed oil, tung oil, soybean oil and the like are mentioned, and compatibility with a polymerization solution of an organic developer, It is selected in consideration of ease of distillation replacement, dissolution stability of the organic developer after solvent replacement, suitability on a printing machine, and the like. The solid content concentration of the organic developer after the replacement with the solvent for the ink is not particularly limited, but the ease of handling the organic developer solution after the replacement and the ink composition with other ink components It can be decided from the relationship, usually
A concentration of about 50 to 80% by weight is preferable.

Further, in the case of the photocurable color developing ink, a (meth) acrylate-based monomer is used, and for example, lauryl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate. Monofunctional monomers such as, diethylene glycol di (meth) acrylate, bifunctional monomers such as tricyclodecane dimethanol (meth) acrylate, polyfunctional such as trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate Examples include monomers. It can also be used in the form of a polyether polyol to which an alkylenoxide is added or a polyester polyol modified with a polybasic carboxylic acid in order to lower skin irritation than a simple polyol (meth) acrylate. .

Examples of the adhesive resin for ink include rosin-modified phenol resin, rosin-modified maleic acid resin,
Examples thereof include petroleum resins, hydrogenated petroleum resins, polyamide resins, butanol-modified amino resins and the like. Further, in the case of photo-curable color developing ink, (meth) acrylic acid ester of polyhydric alcohol, epoxy (meth) acrylate, rosin-modified epoxy (meth) acrylate, polyester (meth) acrylate, polyurethane (meth) acrylate, Examples thereof include (meth) acrylate-based prepolymers such as polyether (meth) acrylate and alkyd (meth) acrylate.

Examples of pigments useful in the present invention include titanium oxide, calcium carbonate, aluminum hydroxide, alumina white, barium sulfate, zinc oxide, kaolin, activated clay and the like, and the content is 0 in the ink. ~ 50% by weight, preferably 5-30% by weight.

The color-developing ink of the present invention further comprises a dispersant,
Waxes, oils, adhesive resins, synthetic resins for improving offset printing suitability, ultraviolet absorbers, antioxidants, fluorescent dyes, starch, anti-setoff agents such as dextrin,
A drying accelerator or the like may also be used as appropriate. In the case of the photocurable color developing ink, a polymerization inhibitor may be added for the purpose of preventing polymerization by heating when the low boiling point solvent is distilled and replaced with the photocurable ink solvent. A photopolymerization initiator is added at the stage of kneading meat, and typical examples thereof include acetophenone-based, benzoin-based, anthraquinone-based, oxime-based, xanthone-based, and thioxanthone-based photopolymerization initiators.

The color-developing ink of the present invention is prepared by mixing or compatibilizing the above-mentioned organic color developer solution with an adhesive resin for ink, a pigment, and other ink components, and kneading the mixture using a necessary three-roll mill or the like. Can be manufactured by.

The amount of the color-developing ink applied to the paper by printing is 0.5 to 5 g / m ² , preferably 1 to 3 g / m ² as the ink.

[0022]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.
In addition, "parts" in the examples means "parts by weight".

[Preparation of Organic Developer Solution-1] 138 parts of salicylic acid was added to 346 parts of toluene, heated to 100 ° C., and 9.5 parts of methanesulfonic acid was added with stirring. Further, 208 parts of styrene was gradually added, and the reaction was continued until the residual styrene became 0.05% or less. Next, 63 parts of basic zinc carbonate was added little by little, and the mixture was stirred so as to be uniform to obtain a toluene solution of zinc salt of salicylic acid-styrene reaction product. 186 parts of the ink solvent shown in Table 1 was added to the obtained toluene solution of salicylic acid-styrene reaction product zinc salt, and heated under reduced pressure to remove toluene by distillation. In this way, a solvent solution for ink of salicylic acid-styrene reaction product zinc salt was obtained. The salicylic acid-styrene reaction product zinc salt was measured by NMR,
It was confirmed that the main component was 3,5-di- (α-methylbenzyl) salicylic acid zinc salt. (Abbreviated as salicylic acid type in the table below)

[Preparation of Organic Developer Solution-2] 850 parts of P-phenylphenol, 112 parts of paraformaldehyde having a purity of 80%, 8.5 parts of p-toluenesulfonic acid and 800 parts of benzene were placed in a glass flask and stirred. While heating. The azeotrope mixture of benzene and water that distills off is cooled, condensed and separated. The aqueous layer is separated and benzene is refluxed in the flask. When the distillation of water was stopped, the reaction was stopped, 485 parts of the ink solvent shown in Table 1 was added, and the mixture was heated under reduced pressure to remove benzene by distillation. Thus, an ink solvent solution of P-phenylphenol formaldehyde resin was obtained. (Abbreviated as phenol in the table below)

Examples 1 to 3 [Preparation of color-developing ink] Using the organic color developer solutions obtained by using the solvent for inks shown in Examples 1 to 3 of Table 1, about 100 was prepared according to the following formulation. After mixing under the condition of ° C, the developer inks of Examples 1 to 3 were prepared by kneading with a three-roll mill. Organic developer solution 75 parts Rosin-modified phenolic resin 10 parts Titanium oxide (Product name: TYPAKE CR93, manufactured by Ishihara Sangyo) 15 parts

Examples 4 to 6 [Preparation of color developing ink] Using the organic color developer solutions obtained by using the photocurable ink solvents shown in Examples 4 to 6 of Table 2, the following formulation was prepared. Example 4 by heating to about 40 ° C., mixing and kneading with a three-roll mill.
-6 color developing inks were obtained. Organic developer solution 65 parts Pentaerythritol tetraacrylate 20 parts Titanium oxide (trade name: Thailake CR93, Ishihara Sangyo) 10 parts α, α'-diethoxyacetophenone 5 parts

[0027]

[Table 1]

[0028]

[Table 2]

Comparative Examples 1 to 6 Solid 3,5-di- (α-methylbenzyl) salicylic acid zinc salt or P-phenylphenol formaldehyde resin 346 parts was used as an ink solvent 186 shown in Tables 1 and 2.
In addition to the parts, the mixture was heated to 140 ° C. and dissolved, and the developer inks of Comparative Examples 1 to 3 were prepared in the same manner as the developer ink preparation of Example 4 in the same manner as the developer ink preparation of Example 1. Comparative Example 4
-6 color developing inks were obtained.

Using the color-developing inks of Examples 1 to 6 and Comparative Examples 1 to 6 described above, evaluation was performed by the following methods. The evaluation results are shown in Tables 1 and 2 above. 1) Inkability Workability The degree of difficulty in dissolution was determined when an organic developer solution was prepared. In the examples according to the present invention, since there is no step of dissolving the solid organic color developer, the judgment is ◯. ◯: Good, ×: Poor 2) RI tester printing suitability With a RI tester (Ming Seisakusho), fine paper (basis weight 40 g /
m ² ), the color-developing ink was printed at a volume of about 2 g / m ² . The quality of the ink fluidity at that time was judged. ◯: Good, Δ: Slightly good, ×: Poor 3) Whiteness of printed part The quality of the printed part whiteness of the printed matter obtained in 2) above was judged. ◯: Good, Δ: Slightly good, ×: Poor 4) Coloring property The printed matter obtained in 2) above was overlaid with NCR paper (manufactured by Mitsubishi Paper Mills) and the quality of the color density after printing on a typewriter was judged. . ○: good, △: somewhat good: ×: bad

In Examples 1, 2, 4, and 5, the workability in ink formation, the printability, the color density, and the whiteness of the printed portion were good without any problems. In Examples 3 and 6, the color development property and the whiteness of the printed portion were slightly good, but they were sufficiently practical. In Comparative Examples 1, 2, 4, and 5, it took time to dissolve the color developer, and the workability to form an ink was poor. Comparative Example 1
It is considered that the whiteness and color developability of Nos. 6 to 6 were worse than those of Examples 1 to 6 due to the dissolution of the organic developer at a high temperature. Further, the reason why the ink fluidity of Comparative Examples 4 to 6 was lowered is considered to be that a part of the photocurable monomer as the ink solvent caused a polymerization reaction when the organic developer was dissolved at a high temperature. .

[0032]

As is clear from the results shown in Tables 1 and 2,
The color-developing ink of the present invention is a color-developing ink which has good solubility of the color-developing agent, good workability for forming an ink, good printability and color density, and excellent whiteness of the printed area. I understand.

Claims (4)

[Claims] 1. An organic developer solution obtained by synthesizing an organic developer in a low-boiling solvent, adding and mixing the solvent for ink, and then removing the low-boiling solvent by distillation. A method for producing a color developing ink, which comprises mixing or compatibilizing an ink component other than the organic color developer solution and kneading to form an ink. 2. The method for producing a color developing ink according to claim 1, wherein at least one of the ink components other than the ink solvent or the organic color developer solution contains a photocurable compound. 3. The method for producing a color developing ink according to claim 1, wherein the organic color developing agent is a salicylic acid derivative polyvalent metal salt. 4. A color-developing ink produced by any one of claims 1 to 3.