JPH04320879A - Developing ink - Google Patents

Abstract

PURPOSE:To obtain a photo-setting type developing ink for a pressure-sensitive recording sheet markedly improved in developability, in the photo-setting type developing ink containing a developer, a photo-setting compound, a photopolymerization initiator and pigment, by adding a specific urethane derivative. CONSTITUTION:In photo-setting type developing ink containing a developer such as a metal salt of aromatic carboxylic acid, a photo-setting compound such as polyacrylate of aromatic dihydric-hexahydric alcohol and polyalkylene glycol, a photopolymerization initiator such as acetophenone and pigment such as zinc oxide, a urethane derivative represented by formula I (wherein R1 and R2 may be same or different and are a hydrogen atom, an aryl group or an alkyl group) is added. As the urethane derivative, N-phenylcarbamoyloxydecane is used. This photo-setting type developing ink for the pressure-sensitive recording sheet is markedly improved in developing capacity and shows good capacity.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photocurable color developing ink for pressure-sensitive recording sheets. More specifically, the present invention relates to a photocurable color developing ink for pressure-sensitive recording sheets that has significantly improved color developing ability.

0002

[Prior Art] A colored image is produced by the reaction between an electron-donating or proton-accepting colorless organic compound (hereinafter referred to as a color former) and an electron-accepting or proton-donating compound (hereinafter referred to as a color developer). It has been known since ancient times that Examples of pressure-sensitive recording paper that specifically utilize this phenomenon include U.S. Pat.
No. 2,712,507, No. 2,730,456, No. 2,730,457, No. 3,418,250, No. 3
, No. 672,935), thermal recording paper (e.g.
-4,160, 43-7,600, 45-14
, No. 039, and U.S. Pat. No. 2,939,009). Furthermore, a printing method is known in which a colored image is obtained by supplying ink containing a color former to a sheet coated with a color developer (German patent OLS 1,939,962). The color developer has the properties defined above, and includes clays, phenolic resins, metal salts of aromatic carboxylic acids, and the like.

[0003] In general, these color developers are usually applied to the entire surface of the support, and desensitizing ink must be printed and applied to areas where the user does not wish to copy to prevent color development. . This operation is very complicated and uneconomical because it requires two coats. In order to solve this drawback, a method has been proposed in which a color developer ink containing a color developer is applied by printing only to necessary portions of the support.

Among the color developing inks used for this purpose, there is a photocurable color developing ink that does not use organic solvents such as acetate esters or alcohols.
, No. 437, JP-A No. 52-141,705, No. 52-
147, 107, etc., in detail.

It is true that the above-mentioned photocurable color developing ink improves ink drying properties by being treated with light irradiation, so the color developing ink is printed on the back side of a sheet coated with microcapsules containing a coloring agent on one side. It also does not cause color fogging and does not use organic solvents, so it is safe for fire safety and health.
It had the advantage of not causing any pollution problems. However, it was found that there was a problem with the color developing ability, which is a characteristic that a color developing ink should have, and that improvement thereof was necessary.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a photocurable color developing ink for pressure-sensitive recording sheets which has significantly improved color developing ability.

[0007]

[Means for Solving the Problems] An object of the present invention is to provide a photocurable color developing ink containing a color developer, a photocurable compound, a photopolymerization initiator, and a pigment, in which a urethane compound represented by the general formula (I) is used. This was achieved by including derivatives. General formula (I)

[0008]

[Case 2]

In the formula, R1 and R2 may be the same or different and represent a hydrogen atom, an aryl group or an alkyl group.

In the urethane derivative of general formula (I),
The group represented by R1 or R2 may have a substituent, and examples of the substitution include an alkyl group, an aryl group, an aryloxy group, a halogen atom, an alkoxy group, an allyl group, and the like. These may further have a substituent. When the group represented by R1 or R2 is an unsubstituted alkyl group, its structure may be linear or branched. Further, the alkyl group may have an ether bond, amide bond, ester bond, carbonyl bond, etc. in the group.

The urethane derivative according to the present invention preferably has a molecular weight of 200 or more, particularly a molecular weight of 25
It is preferable that it is 0 or more.

Next, typical examples of urethane derivatives according to the present invention will be shown. N-phenylcarbamoyloxydecane, N-phenylcarbamoyloxydodecane, N-phenylcarbamoyloxytetradecane, N-phenylcarbamoyloxyhexadecane, N-phenylcarbamoyloxytetradecane, N-phenylcarbamoyloxyeicosane, N-phenylcarbamoyloxymethylbenzene , N-phenylcarbamoyloxyethylbenzene, (2-(N-phenylcarbamoyloxy)ethoxy)benzene, N-octadecylcarbamoyloxymethane, N-octadecylcarbamoyloxyethane, N-octadecylcarbamoyloxybutane, N-octadecylcarbamoyloxyhexane, N-octadecylcarbamoyloxyoctane, N-octadecylcarbamoyloxydecane, N-octadecylcarbamoyloxydodecane, N-octadecylcarbamoyloxytetradecane, N-octadecylcarbamoyloxyhexadecane, N-octadecylcarbamoyloxyoctadecane, N-octadecylcarbamoyloxybenzene, N-octadecylcarbamoyloxy-p-methylbenzene, N-octadecylcarbamoyloxy-
p-ethylbenzene, N-octadecylcarbamoyloxy-p-methoxybenzene, N-octadecylcarbamoyloxy-p-ethoxybenzene, N-octadecylcarbamoyloxy-p-chlorobenzene, N-octadecylcarbamoyloxy-m-methylbenzene, N
Examples include, but are not limited to, -octadecylcarbamoyloxy-o-methylbenzene.

The amount of the urethane derivative of the present invention used is 1 to 100% by weight, preferably 2 to 20% by weight, based on the color developer.

The color developer used in the present invention includes metal salts of aromatic carboxylic acids and phenol resins, and metal salts of aromatic carboxylic acids are preferred. The content of this metal salt of aromatic carboxylic acid in the color developing ink of the present invention is 20 to 3
5% is preferred.

The metal salts of aromatic carboxylic acids used in the present invention are described, for example, in US Pat.
No. 3,292, Japanese Patent Publication No. 51-25174, Japanese Patent Publication No. 62
-19486, JP-A No. 63-254124, etc. The aromatic carboxylic acid in the above-mentioned metal salt of aromatic carboxylic acid is usefully one having a hydroxyl group at the ortho or para position to the carboxy group, and salicylic acid derivatives are particularly preferred, and substituted with an alkyl group, an aryl group, an aralkyl group, etc. It is preferable that the substituents have a total number of carbon atoms of 8 or more.

Specific examples of preferred metal salts of salicylic acid derivatives used in the present invention include 3,5-di-t-butylsalicylic acid, 3,5-di-t-octylsalicylic acid, and 3,5-di-t-octylsalicylic acid.
, 5-di-t-nonylsalicylic acid, 3,5-di-t-dodecylsalicylic acid, 3-methyl-5-t-dodecylsalicylic acid, 3-t-dodecylsalicylic acid, 3-isododecylsalicylic acid, 5-cyclohexylcyclohexylsalicylic acid , 3,5-bis(α-methylbenzyl)salicylic acid, 3,5-bis(α,α-dimethylbenzyl)salicylic acid, 3-methyl-5-(α-methylbenzyl)salicylic acid, 3-(α,α- dimethylbenzyl)-6-methylsalicylic acid, 3-(α-methylbenzyl)-5-(α,
α-dimethylbenzyl)salicylic acid, 3-(α,α-dimethylbenzyl)-6-ethylsalicylic acid, 3-phenyl-5-(α,α-dimethylbenzyl)salicylic acid, 3
-(α-methylbenzyl)-5-t-butylsalicylic acid, 3-(α-methylbenzyl)-5-t-octylsalicylic acid, 3-(α-methylbenzyl)-5-t-octylsalicylic acid, carboxy-modified terpene Examples include zinc salts, nickel salts, aluminum salts, calcium salts, etc. of phenol resin, salicylic acid resin which is a reaction product of 3,5-bis(α-methylbenzyl)salicylic acid and benzyl chloride.

The photocurable compound of the present invention includes (1)
Aliphatic, alicyclic, araliphatic, aromatic di- to hexavalent polyhydric alcohol and polyalkylene glycol polyacrylate or polymethacrylate, (2) Aliphatic, alicyclic, araliphatic, aromatic 2 - Polyacrylate or polymethacrylate of a polyhydric alcohol in the form of an alkylene oxide added to a hexavalent polyhydric alcohol, (3) polyacryloyloxyalkyl phosphate or polymethacryloyloxyalkyl phosphate, (4)
Polyester polyacrylate or polyester polymethacrylate, (5) Epoxy polyacrylate or epoxy polymethacrylate, (6) Polyurethane polyacrylate or polyurethane polymethacrylate, (7) Polyamide polyacrylate or polyamide polymethacrylate, (8) Polysiloxane Examples include polyacrylate or polysiloxane polymethacrylate. Among these, compounds (1) and (2) are particularly preferred.

Examples of the photopolymerization initiator of the present invention include benzoin alkyl ethers, acetophenones, benzyl ketals, benzophenones, and thioxanthone. Among these, acetophenones are particularly preferred, specifically 2-methyl-1-[4-(methylthio)
-phenyl]-2-morpholino-1-propanone, 2-
Hydroxy-2-methyl-1-phenyl-1-propanone and the like.

Examples of pigments include titanium oxide and zinc oxide, but it is preferable to use alumina white in combination.

As other additives for the color developing ink of the present invention, heat-reactive polymerization inhibitors, waxes, etc. may be added as necessary.

[0021] In the present invention, the color developer ink may be produced by any conventional method, and first, a color developer, a photocurable compound, a urethane derivative, and a thermally reactive polymerization inhibitor are mixed and dissolved by heating to prepare a varnish. Next, a photopolymerization initiator, a pigment, a wax, and optionally a photocurable compound for fluidity control are added to this varnish, and the mixture is kneaded using a three-roll mill.

The color developing ink produced according to the present invention can be spot-printed on the surface of high-quality paper, the surface of a film base, or the back side of a sheet coated with microcapsules containing a coloring agent on one side using a printing machine in areas where copying is required. The printed surface is immediately cured by light irradiation. The printing method is preferably an offset method, but a letterpress method may also be used. A mercury lamp, a metal halide lamp, or the like is used as a light irradiation source.

The printing coating amount of the color developing ink of the present invention is 0.5
-3 g/m2, preferably 1-2 g/m2.

The coloring agent that develops color on the printed surface of the color developing ink of the present invention is not particularly limited, but includes triphenylmethanephthalide compounds, fluoran compounds, phenothiazine compounds, indolylphthalide compounds, and leucoauramine. Examples include rhodamine lactam compounds, triphenylmethane compounds, triazene compounds, spiropyran compounds, and fluorene compounds. Specific examples of phthalides are U.S. Pat. No. 23,024, U.S. Pat.
No. 491,111, No. 3,491,112, No. 3
, 491,116, 3,509,174, and specific examples of fluorans are U.S. Pat. No. 462,828, No. 3,681,390,
Nos. 3,920,510 and 3,959,571; specific examples of spirodipyrans are US Pat. No. 3,971;
No. 808, pyridine and pyrazine compounds are disclosed in U.S. Pat. No. 3,775,424 and U.S. Pat. No. 3,853,869,
No. 4,246,318, and specific examples of fluorene compounds are described in Japanese Patent Application No. 61-240989.

[0025] The coloring agent is dissolved in a solvent, encapsulated, and applied to a support. As the solvent, natural or synthetic oils can be used alone or in combination. Examples of solvents include cottonseed oil, kerosene, paraffin oil, naphthenic oil, alkylated biphenyls, alkylated terphenyls, chlorinated paraffins, alkylated naphthalenes, diphenylalkanes, and the like. As a method for producing color former-containing microcapsules, an interfacial polymerization method, an internal polymerization method, a phase separation method, an external polymerization method, a coacervation method, etc. are used. A water-soluble binder or a latex binder is generally used to prepare a coating solution containing microcapsules containing a color former. Further, cellulose powder, starch particles, talc, etc. are added as a capsule protectant to obtain a coloring agent-containing microcapsule coating liquid.

The color developing ability of the printed surface with the color developing ink of the present invention was confirmed using the following color former-containing microcapsule sheet. (Preparation of microcapsule sheet containing coloring agent) While stirring 5 parts of a partial sodium salt of polyvinyl sulfonic acid (manufactured by National Starch Co., Ltd., VERSA, TL500, average molecular weight 500,000) in 95 parts of hot water at about 80°C. Cool after adding and dissolving. The pH of the aqueous solution is 2~
3, and a 20% by weight aqueous sodium hydroxide solution was added thereto to adjust the pH to 4.0. On the other hand, 2.5% crystal violet lactone and 1.0% benzoylleucomethylene blue were dissolved in diisopropylnaphthalene 10.
0 part was emulsified and dispersed in 100 parts of a 5% aqueous solution of a partial sodium salt of the polyvinylbenzenesulfonic acid to obtain an average diameter of 4.
．． An emulsion with a particle size of 5 μm was obtained. Separately, add 6 parts of melamine and 11 parts of a 37% by weight formaldehyde aqueous solution to 6 parts.
Thirty minutes after heating and stirring at 0° C., a transparent mixed aqueous solution of melamine, formaldehyde and melamine-formaldehyde initial condensate was obtained. The pH of this mixed aqueous solution was 6-8. Hereinafter, this mixed aqueous solution of melamine, formaldehyde, and melamine-formaldehyde initial condensate will be referred to as an initial condensate solution. The initial condensate solution obtained by the above method was added to the above emulsion and mixed, and while stirring, 3.6% by weight
The pH was adjusted to 6.0 with a hydrochloric acid solution, the temperature of the solution was raised to 65°C, and stirring was continued for 360 minutes. This capsule liquid was cooled to room temperature and added with a 20% by weight aqueous sodium hydroxide solution to pH 9.
Adjusted to 0. 10% by weight based on this capsule dispersion
200 parts of a polyvinyl alcohol aqueous solution and 50 parts of starch particles were added, and water was added to adjust the solid content concentration to 20% to prepare a color former-containing microcapsule coating solution. This coating solution was coated on a 50 g/m2 base paper using an air knife coater so that the solid content was 5 g/m2, and dried to obtain a color former-containing microcapsule sheet. The photocurable color developing ink for pressure-sensitive recording of the present invention will be specifically explained below with reference to Examples, but the invention is not limited to these Examples.

[0027]

[Example] Example 1 Zinc 3,5-di-(α-methylbenzyl)salicylate 5
0 parts, N-phenylcarbamoyloxytetradecane 5
part, di-trimethylolpropane tetraacrylate 2
0 parts, 30 parts of propylene oxide adduct of neopentyl glycol diacrylate, and 0.1 part of N-nitrosophenylhydroxylamine ammonium salt at 110°
The mixture was heated to C and uniformly dissolved to obtain a varnish. To 62 parts of this varnish, 4 parts of 2-methyl-1-[4-(methylthio)-phenyl]-2-morpholino-1-propanone, 3 parts of 2-hydroxy-2-methyl-1-phenyl-1-propanone, and polyethylene 3 parts wax, 10 parts titanium oxide,
Furthermore, alumina white (average particle size 0.07 microns,
Refractive index: 1.50, bulk specific gravity: 900 ml/g) 8 parts were milled in a three-roll mill, and finally 10 parts of a propylene oxide adduct of neopentyl glycol diacrylate was added to obtain a color developing ink.

Example 2 Zinc 3,5-di-(α-methylbenzyl)salicylate 5
0 parts, N-octadecylcarbamoyloxybenzene 5
parts, 20 parts of polyester acrylate oligomer, 1 part,
30 parts of 6-hexanediol diacrylate and 0.0 parts of N-nitrosophenylhydroxylamine ammonium salt.
One part was heated to 110°C and uniformly dissolved to obtain a varnish. To 62 parts of this varnish, 4 parts of 2-methyl-1-[4-(methylthio)-phenyl]-2-morpholino-1-propanone, 2-hydroxy-2-methyl-1-phenyl-
3 parts of 1-propanone, 3 parts of polyethylene wax, 10 parts of titanium oxide, and alumina white (average particle size 0.
1 micron, refractive index 1.56, bulk specific gravity 600ml/g)
Eight parts were milled using a three-roll mill, and finally 10 parts of 1,6-hexanediol diacrylate were added to obtain a color developing ink.

Example 3 A developing ink was obtained in the same manner as in Example 1 except that N-(p-chlorophenyl)carbamoyloxytetradecane was used instead of N-phenylcarbamoyloxytetradecane.

Example 4 A developing ink was obtained in the same manner as in Example 1 except that N-(p-methoxyphenyl)carbamoyloxyhexadecane was used instead of N-phenylcarbamoyloxytetradecane.

Comparative Example 1 A color developing ink was obtained in the same manner as in Example 1 except that 5 parts of N-phenylcarbamoyloxytetradecane was not used.

The above color developing ink was printed at 1.5 g/m 2 on the surface of 50 g/m 2 high-quality paper using an offset printing machine. Uses a metal halide lamp with an output of 8KW and a speed of 80
Printed at m/min.

[0033] A color developer sheet printed with each of the above color developer inks and a color former-containing microcapsule sheet were combined to form 30 sheets.
A loading pressure of 0 kg/cm2 was applied for 5 seconds to develop color, and the color density after one day was measured using a Macbeth reflection densitometer. The results are listed in Table 1.

[0034]

[Table 1]

[0035]

[Effects of the Invention] As shown in Table 1, the color developing ink of the present invention has significantly improved color developing ability and good performance compared to the comparative color developing ink.

Claims (1)

[Claims] [Claim 1] A photocurable color developer ink containing a color developer, a photocurable compound, a photopolymerization initiator, and a pigment, characterized by containing a urethane derivative represented by the following general formula (I). Photocurable color developing ink for pressure-sensitive recording sheets. General formula (I) [Image Omitted] In the formula, R1 and R2 may be the same or different and represent a hydrogen atom, an aryl group, or an alkyl group.