JPH05278327A - Developing ink - Google Patents

Abstract

PURPOSE:To improve developing capacity such that no developed color fog is generated at the time of printing by preparing photo-setting developing ink by compounding 3,5-bis(alpha-methylbenzyl) salicylic acid and a zinc salt of a specific salicylic acid derivative. CONSTITUTION:An alkali metal salt of a salicylic acid derivative represented by formula I (wherein R1 is a hydrogen atom or an alkyl group, R2 is an alkyl group, X is an alkyl group and Y is an alkyl group or an aryl group) is reacted with a zinc compd. to synthesize a salicylic acid derivative zinc salt mixture which is, in turn, compounded with 3,5-bis (alpha-methylbenzyl) salicylic acid to prepare a developer. This developer, a photo-setting compd. and a thermal reaction/polymerization inhibitor are mixed and dissolved under heating to prepare varnish. A photopolymerization initiator, pigment, waxes and, if necessary, a photo-setting compd. are added to said varnish and the resulting compsn. is kneaded by a three-roll mill to prepare photo-setting developing ink for a pressure-sensitive recording sheet.

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, it relates to a photo-curable developer ink for a pressure-sensitive recording sheet, which has a significantly improved developer ability.

[0002]

2. Description of the Related Art A color image is formed by a 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 developer). It has long been known to gain. Pressure-sensitive recording paper (for example, U.S. Pat. Nos. 2,505,470 and 2,505,489;
Issue 2, Issue 2,505,471, Issue 2,548,366
Issue 2, Issue 2,712,507, Issue 2,730,456
Issue 2, Issue 2,730,457, Issue 3,418,250
No. 3,672,935), thermal recording paper (for example, Japanese Examined Patent Publication Nos. 43-4,160, 43-7,600 and 4).
5-14,039, US Pat. No. 2,939,009)
Etc. Furthermore, a printing method is known in which an ink containing a color-developing agent is supplied to a sheet coated with a color-developing agent to obtain a colored image (German Patent OLS 1,939,962).
The color developer has the properties defined previously, and examples thereof include clays, phenol resins, and metal salts of aromatic carboxylic acids.

In general, these color developing agents are usually applied on the entire surface of a support, and a desensitizing ink must be applied by printing to a portion where a user does not want to copy to prevent color development. .. This operation is very complicated and uneconomical because it requires two coatings. In order to solve this drawback, a method has been proposed in which a color-developing ink containing a color-developing agent is applied by printing on only a necessary portion of the support.

Among the color-developing inks used for such purposes, there is a photo-curable color-developing ink which does not use organic solvents such as acetic acid esters and alcohols.
No. 8,437, 52, 141,705 and 52.
-147,107 and the like. Specific examples are 3,5-di-t-butylsalicylic acid and 3,5-di-
t-octylsalicylic acid, 3,5-di-t-nonylsalicylic acid, 3,5-di-t-dodecylsalicylic acid, 3-methyl-5-t-dodecylsalicylic acid, 3-t-dodecylsalicylic acid, 3-isododecylsalicylic acid , 5-cyclohexylcyclohexyl salicylic 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-
Ethyl salicylic 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 phenolic resin, 3,5-bis (α-
(Methylbenzyl) zinc salt, salicylic acid resin, etc., which is a reaction product of salicylic acid and benzyl chloride, nickel salt,
Examples thereof include aluminum salt and calcium salt.

Certainly, the above photo-curable color developing ink has a better ink drying property when subjected to light irradiation treatment, so that the color developing ink is printed on the back surface of a sheet coated with microcapsules containing a color former on one side. Even if it does not cause color fog, or because it does not use organic solvents, it is good for fire protection and health,
It had the excellent point that there was no pollution problem. However, it has been found that the above photo-curable color developing ink has a problem in color developing ability, which is a characteristic that the color developing ink originally has, and needs to be improved.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a photo-curable developer ink for pressure-sensitive recording sheet, which has a markedly improved developer ability.

[0007]

The object of the present invention is to provide a photo-curable developer ink containing a developer, a photo-curable compound, a photo-polymerization initiator and a pigment as a developer a) 3,5- Bis (α-methylbenzyl) salicylic acid and b) the salicylic acid derivative represented by the general formula (I) is achieved by using a salicylic acid derivative zinc salt mixture obtained by reacting each alkali metal salt with a zinc compound. It was

[0008]

[Chemical 2]

(In the above formula, R ₁ is a hydrogen atom or an alkyl group, R ₂ is an alkyl group, X is an alkyl group, and Y is an alkyl group or an aryl group.) That is, the developer of the present invention is used. By using it, a photo-curable color developing ink having excellent color developing ability can be obtained. As a result of various investigations for overcoming the above-mentioned conventional drawbacks, the inventors of the present invention improved the color developing agent contained in the photocurable color developing ink to cause a change in color developing ability, and further, a salicylic acid derivative as a color developing agent. It was found that the use of the zinc salt of No. 2 improved the color developing ability of the color developing ink, and in particular, when the zinc salt of the general formula (I) was used, the degree of improvement of the color developing ability was great.

However, the zinc salt of the formula (I) has a drawback that it is easily crystallized and has a low oil solubility and is difficult to be made into an ink, which makes it unsuitable for practical use. Therefore, as a result of further investigations by the present inventors to solve these drawbacks, 3,5-bis (α-
Methylbenzyl) salicylic acid [developing agent a) of the present invention] and a salicylic acid derivative of the above formula (I) [developing agent b) of the present invention are used in combination to obtain an unexpected effect. It was possible to obtain a color-developing ink which suppressed the crystallization of the zinc salt of the formula (I) and had an excellent color-developing ability.

In the present invention, it is preferable that the a) alkali metal salt of salicylic acid and the b) alkali metal salt of salicylic acid are simultaneously reacted with a zinc compound and used as a mixture of zinc salts. Hereinafter, the present invention will be described in more detail. In general formula (I), among the substituents represented by R ₁ and R ₂ , an alkyl group having 1 to 8 carbon atoms is preferable,
Of the substituents represented by X, an alkyl group having 1 to 4 carbon atoms is preferable, and among the groups represented by Y, the number of carbon atoms is 1 to 9
And an alkyl group having 6 to 24 carbon atoms are preferable.

These substituents may further have a substituent, and examples thereof include an alkyl group, an alkoxy group, a halogen atom, an acyl group, an aryl group, an aryloxy group and a sulfonyl group. These may further have a substituent. Specific examples of the salicylic acid derivative represented by the general formula (I) are shown below. 3-cumyl-6-
Methylsalicylic acid, 3-benzylcumyl-6-methylsalicylic acid, 3-α-methyl-α-ethylbenzyl-6-
Methylsalicylic acid, 3-α-methyl-α-propylbenzyl-6-ethylsalicylic acid, 3-cumyl-6-ethylsalicylic acid, 3-benzylcumyl-6-ethylsalicylic acid, 3-α-methyl-α-ethylbenzyl-6- Ethyl salicylic acid, 3-α-methyl-α-propylbenzyl-
6-ethylsalicylic acid, 3-cumyl-6-propylsalicylic acid, 3-cumyl-6-butylsalicylic acid, 3-methylcumyl-6-methylsalicylic acid, 3-dimethylcumyl-6-methylsalicylic acid, 3-t-butyl-6-butyl Salicylic acid, 3-t-octyl-6-methylsalicylic acid, 3-t-nonyl-6-methylsalicylic acid, 3-t-
Dodecyl-6-methylsalicylic acid, 3-t-octyl-
6-ethylsalicylic acid, 3-t-nonyl-6-ethylsalicylic acid, 3-t-dodecyl-6-ethylsalicylic acid,
3-t-nonyl-6-ethylsalicylic acid, and the like.

In the present invention, the mixing ratio of 3,5-bis (α-methylbenzyl) salicylic acid and the salicylic acid derivative represented by the general formula (I) is 5/95 to 95 in terms of molar ratio.
/ 5, preferably 20/80 to 80/20, particularly preferably 33/67 to 67/33. Further, as the alkali metal salt, lithium, sodium, potassium or the like is used.

Examples of the zinc compound according to the present invention include zinc oxide, zinc hydroxide, zinc carbonate, zinc sulfate and zinc chloride. Among these, it is particularly preferable to use an alkali metal salt of a salicylic acid derivative and a zinc salt such as zinc sulfate and zinc chloride, and the post-treatment after zinc chloride is extremely easy. The zinc salicylic acid derivative mixture according to the present invention can be easily obtained by reacting two or more alkali metal salts of the salicylic acid derivative of the present invention with a zinc compound in water or a mixture of water and an organic solvent.

Particularly, the method of zinc chloride in a mixture of water and an organic solvent is preferable because it has advantages in operability during production, and the yield and purity of zinc chloride. As the organic solvent, those having low solubility in water and high solubility of the zinc salt of the salicylic acid derivative are preferable, and examples thereof include aromatic compounds, halides and ester compounds. Specific examples include toluene, xylene, trichlene, ethyl acetate and the like.

The photocurable compound used in the present invention is
(1) Aliphatic, alicyclic, araliphatic, aromatic polyhydric alcohols having 2 to 6 valences and polyacrylates or polymethacrylates of polyalkylene glycols, (2) aliphatic,
Alicyclic, araliphatic, polyhydric alcohol polyacrylate or polymethacrylate in a form obtained by adding alkylene oxide to aromatic polyhydric alcohol of 2 to 6;
(3) Polyacryloyloxyalkyl phosphate ester or polymethacryloyloxyalkyl phosphate ester, (4) Polyester polyacrylate or polyester polymethacrylate, (5) Epoxy polyacrylate or epoxy polymethacrylate, (6) Polyurethane polyacrylate Alternatively, polyurethane polymethacrylate, (7) polyamide polyacrylate or polyamide polymethacrylate, (8) polysiloxane polyacrylate or polysiloxane polymethacrylate may, for example, be mentioned. Of these, the compounds (1) and (2) are particularly preferable.

Examples of the photopolymerization initiator used in the present invention include benzoin alkyl ethers, acetophenones, benzyl ketals, benzophenones and thioxanthones. Of these, acetophenones are particularly preferable, and specifically, 2-methyl-1- [4- (methylthio) -phenyl] -2-morpholino-1-propanone, 2-hydroxy-2-methyl-1-phenyl- 1-
Propanon etc.

Examples of the inorganic pigments used in the present invention include white pigments such as titanium oxide and zinc oxide. Alumina previously proposed by the applicant of the present invention is excellent in color developing ability and improves offset printing suitability. White (Japanese Patent Application No. 3-523)
No. 99) is preferably used. As other additives of the color developing ink of the present invention, a thermal reaction polymerization inhibitor, waxes and the like are added if necessary.

In the present invention, the method for producing the color developing ink may be a usual method. First, the color developing agent, the photocurable compound and the thermal reaction polymerization inhibitor are mixed and heated to form a varnish. Then, a photopolymerization initiator, a pigment, a wax and, if necessary, a photocurable compound for adjusting fluidity are added to the varnish and the mixture is kneaded by a three-roll mill to complete the varnish.

The color-developing ink produced by the present invention is spot-printed on a copy-needed portion using a printing machine on the surface of fine paper, the surface of a film base, or the back surface of a sheet coated with microcapsules containing a color former on one surface. The printed surface is immediately cured by irradiation with light. An offset method is used as the printing method. A mercury lamp, a metal halide lamp, or the like is used as the light irradiation source.

The coating amount of the color developing ink of the present invention is 0.5.
-3 g / m < ² >, preferably 1-2 g / m < ² >. The color-developing agent that develops color on the color-developed ink printing coated surface of the present invention is not particularly limited, but a triphenylmethanephthalide compound,
Examples thereof include fluoran compounds, phenothiazine compounds, indolylphthalide compounds, leuco auramine compounds, rhodamine lactam compounds, triphenylmethane compounds, triazene compounds, spiropyran compounds, and fluorene compounds. Specific examples of phthalides include U.S. Pat. Nos. 23,024 and 3,491,111.
No. 3,491,112, No. 3,491,11
6, No. 3,509,174, and specific examples of fluoranes are U.S. Pat. Nos. 3,624,107 and 3,62.
No. 7,787, No. 3,641,011, No. 3,4
No. 62,828, No. 3,681,390, No. 3,
920,510, 3,959,571, and specific examples of spiro dipyrans are described in US Pat. No. 3,971,808.
U.S. Pat. No. 3,775,424, U.S. Pat. No. 3,853,869, U.S. Pat. No. 4,246,318, and fluorene compounds are disclosed in Japanese Patent Application No. 61- No. 240989 and the like.

The color former 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 the solvent include cottonseed oil, kerosene, paraffin oil, naphthene oil, alkylated biphenyl, alkylated terphenyl, chlorinated paraffin, alkylated naphthalene, diphenylalkane and the like. As a method for producing the color-forming agent-containing microcapsules, an interfacial polymerization method, an internal polymerization method, a phase separation method, an external polymerization method, a coacervation method and the like are used. A water-soluble binder or a latex binder is generally used for preparing a coating liquid containing a color-forming agent-containing microcapsule. Further, cellulose powder, starch particles, talc, etc. are added as a capsule protecting agent to obtain a color developer-containing microcapsule coating solution.

The color-developing ability of the printing surface of the color-developing ink of the present invention was confirmed using the following microcapsule sheet containing a color-forming agent. (Preparation of Microcapsule Sheet Containing Coloring Agent) Partial Sodium Salt of Polyvinyl Sulfonic Acid (made by National Starch, VERSA, TL500, average molecular weight 500,0)
5 parts of 00) are added to 95 parts of hot water of about 80 ° C. with stirring to dissolve and then cooled. The pH of the aqueous solution is 2-3
20 wt% sodium hydroxide aqueous solution was added to this
It was set to 4.0. On the other hand, crystal violet lactone 4
And 100 parts of diisopropylnaphthalene having 2 parts of 3- [4- (diethylamino) -2-ethoxyphenyl] -3- (2-methyl-1-octyl-3-indolyl) -4-azaphthalide dissolved therein are added to the polyvinylbenzenesulfone. By emulsifying and dispersing in 100 parts of a 5% aqueous solution of a partial sodium salt of an acid, an emulsion having a particle size of 4.5 μm in average diameter was obtained. Separately, 6 parts of melamine and 11 parts of 37% by weight aqueous formaldehyde solution were heated and stirred at 60 ° C., and after 30 minutes, a transparent mixed aqueous solution of melamine, formaldehyde and melamine-formaldehyde initial condensation product was obtained. The pH of this mixed aqueous solution was 6-8. Hereinafter, the mixed aqueous solution of melamine, formaldehyde, and melamine-formaldehyde precondensate will be referred to as an initial condensate solution. The initial condensate solution obtained by the above method was added to and mixed with the above emulsion, the pH was adjusted to 6.0 with a 3.6 wt% hydrochloric acid solution while stirring, the liquid temperature was raised to 65 ° C. and 360 minutes. Continued to stir. The capsule solution was cooled to room temperature and adjusted to pH 9.0 with a 20 wt% sodium hydroxide aqueous solution. 200 wt% polyvinyl alcohol aqueous solution based on this capsule dispersion
And 50 parts of starch particles were added, and water was added to adjust the solid content concentration to 20% to prepare a color developer-containing microcapsule coating solution. This coating solution was added to 5 g / m ² of 50 g / m ² base paper.
It applied by an air knife coater so m ² solids is applied and dried to obtain color former containing microcapsules sheet. Hereinafter, the photocurable color developer ink for pressure-sensitive recording of the present invention will be specifically described with reference to examples, but the present invention is not limited to the examples.

[0024]

【Example】

[Method for producing developer A] 7.0 g of 3,5-bis- (α-methylbenzyl) salicylic acid, 7.0 g of 3- (α, α-dimethylbenzyl) -6-methylsalicylic acid and 1.7 g of caustic soda were added. The mixture was added to 200 ml of water, heated to 70 ° C., stirred and dissolved. Then, a solution prepared by dissolving 6 g of zinc sulfate heptahydrate in 100 ml of water was added dropwise to this solution over 10 minutes.
After stirring for 30 minutes, the mixture is cooled to 50 ° C., 50 ml of ethyl acetate is added to dissolve the precipitate, and the layers are separated. Ethyl acetate was distilled off under reduced pressure to give 3,5-bis- (α-methylbenzyl).
Salicylic acid and 3- (α, α-dimethylbenzyl)-
Amorphous solid color developer A of a mixed zinc salt of 6-methylsalicylic acid was obtained. [Method for producing developer B] 3- (α, α-dimethylbenzyl) -6-methylsalicylic acid 7.0 g instead of 7.0 g
(Α-Methylbenzyl) -6-ethylsalicylic acid 7.0
Developer B was obtained in the same manner as in [Production method of developer A] except that g was used. [Method for producing color developer C] 3- (α, α-dimethylbenzyl) -6-methylsalicylic acid 7.0 g instead of 3-g
A developer C was obtained in the same manner as in [Production method of developer A] except that 7.0 g of t-octyl-6-methylsalicylic acid was used. [Method for producing color developer D] 3- (α, α-dimethylbenzyl) -6-methylsalicylic acid 7.0 g instead of 3-
A developer D was obtained in the same manner as in [Production method of developer A] except that 7.0 g of t-nonyl-6-ethylsalicylic acid was used. [Production Method of Developer E] 3,5-bis- (α-methylbenzyl) salicylic acid 7.0 g, 3- (α, α-dimethylbenzyl) -6-methylsalicylic acid 7.0 g A developer E was obtained in the same manner as in [Production method of developer A] except that 14.0 g of 5-bis- (α-methylbenzyl) salicylic acid was used. [Method for producing developer F] 3,5-bis- (α-methylbenzyl) salicylic acid 7.0 g, 3- (α, α-dimethylbenzyl) -6-methylsalicylic acid 7.0 g A developer F was obtained in the same manner as in [Production method of developer A] except that 14.0 g of (α, α-dimethylbenzyl) -6-methylsalicylic acid was used. Example 1 50 g of color developer A, 20 g of di-trimethylolpropane tetraacrylate, 30 g of propylene oxide adduct of neopentyl glycol diacrylate, and N-nitrosophenylhydroxylamine ammonium salt 0.1.
g was heated to 110 ° C. and uniformly dissolved to obtain a varnish.
To 62 g of this varnish was added 2-methyl-1- [4- (methylthio) -phenyl] -2-morpholino-1-propanone 4
g, 2-hydroxy-2-methyl-1-phenyl-1-
3 g of propanone, 3 g of polyethylene wax, 10 g of titanium oxide, and further alumina white (average particle size 0.07
Micron, refractive index 1.50, bulk specific gravity 900 ml / g) 8
g was kneaded with a three-roll mill, and finally propylene oxide adduct of neopentyl glycol diacrylate 1
0 g was added to obtain a color developing ink. Example 2 A color developing ink was obtained in the same manner as in Example 1 except that the color developing agent B was used in place of the color developing agent A. Example 3 A color developing ink was obtained in the same manner as in Example 1 except that the color developing agent C was used in place of the color developing agent A. Example 4 A color developing ink was obtained in the same manner as in Example 1 except that the color developing agent D was used in place of the color developing agent A. Comparative Example 1 A color developing ink was obtained in the same manner as in Example 1 except that the color developing agent E was used in place of the color developing agent A. Comparative Example 2 A color developing ink was obtained in the same manner as in Example 1 except that the color developing agent F was used in place of the color developing agent A.

The color-developing inks obtained in Examples 1 to 4 and Comparative Examples 1 and ^{2 were} printed on a surface of 50 g / m ² fine paper with an offset printing machine at 1.5 g / m ² . Printing was performed at a speed of 80 m / min using a metal halide lamp with an output of 8 kW. 300 kg by combining the color-developing sheet printed with each color-developing ink and the microcapsule sheet containing the color-developing agent
Color was developed for 5 seconds under a load pressure of / cm ² , and the color density after one day was measured with a Macbeth reflection densitometer. The results are shown in Table 1.
Described in.

[0026]

[Table 1]

As shown in Table 1, the color-developing ink of the present invention has remarkably improved color-developing ability as compared with the color-developing ink for comparison, and has good performance.

[0028]

By using the color developing agent of the present invention, a photo-curable color developing ink for a pressure sensitive recording sheet having excellent color developing ability can be obtained.

Claims (1)

[Claims] 1. A photocurable developer ink comprising a developer, a photocurable compound, a photopolymerization initiator and a pigment, wherein a) 3,5-bis (α-methylbenzyl) salicylic acid and b as a developer. ) A photo-curable type light-sensitive recording sheet for pressure-sensitive recording sheet, characterized in that a mixture of salicylic acid derivative represented by the general formula (I) and a zinc salt of a salicylic acid derivative obtained by reacting a zinc compound is used. Color ink. General formula (I): In the above formula, R ₁ represents a hydrogen atom or an alkyl group, R ₂ represents an alkyl group, X represents an alkyl group, and Y represents an alkyl group or an aryl group.