JPH0326670B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a developer ink for pressure-sensitive copying paper using a novel developer. Various forms of pressure-sensitive copying paper are known. In general, it is an application of the fact that a leuco dye (hereinafter referred to as a color former), which is an electron donating substance, and an electron accepting substance (hereinafter referred to as a color developer) react to form a colored substance. That is, a top sheet of paper in which a coloring agent is dissolved in a non-volatile solvent and a microcapsule of this solution is applied to the back side of a support, and a bottom sheet of paper in which a color developer is applied to the surface of the support are used as a unit. When pressure is applied with the coated surfaces facing each other, the capsules coated on the back side of the top paper break and a solution containing the coloring agent oozes out, which then comes into contact with the color developer coated on the bottom paper and develops color on the copying paper. be. In addition, copying paper in which an inner paper coated with a color developer on the surface of the upper paper is sandwiched between the upper paper and the lower paper to form an upper-middle-lower unit and pressurized in the same manner to record three copies, and the capsule. There is a self-coloring pressure-sensitive copying paper in which color developer and color developer are coated on the same paper surface. These pressure-sensitive copying papers usually have two components, a color former and a color developer, applied singly or in combination over the entire surface of the paper, and if there are areas that do not want to be copied,
It is manufactured either by printing and applying a desensitizing ink to prevent the color from developing in the area concerned, or by applying the above-mentioned two components singly or in combination only to the desired area. ing. The latter manufacturing method mentioned above is a partial printing method, which is generally called a spot printing method. The present invention relates to a developing ink for flexo/gravure used in spot printing.
Conventionally, color developing inks using clays described in Japanese Patent Publication No. 43-28430 are known as color developing inks used in spot printing methods, but these clays do not have sufficient color developing ability due to their attributes. Instead, the amount of coating has to be increased, resulting in an increase in coating thickness, and since strong pressure is applied during storage and use during stacking, coloring also occurs in unnecessary areas, which is undesirable. Next, in order to avoid the adverse effects of these viscosities,
For example, as described in Japanese Patent Publication No. 49-27134, an improvement has been proposed for developing color inks in which aromatic carboxylic acids or their anhydrides coexist with metal compounds. Further, Japanese Patent Publication No. 42-20144 discloses a flexo/gravure ink called resin spot ink in which a phenol-formalin resin is dissolved. However, none of them has yet been satisfactory in terms of color development, light resistance, and plasticizer resistance. As a result of intensive research on these color developer inks for flexographic and gravure printing, the present inventors found that color developer inks for pressure-sensitive copying that are mainly composed of an electron-accepting color developer, a pigment, a binder, and an organic solvent. p-hydroxybenzoic acid and 1 carbon number as color developer
A condensate obtained by reacting a p-substituted alkylphenol having ~12 alkyl groups with formaldehyde in the presence of an acidic catalyst and mixing or reacting the condensate with a polyvalent metal compound, or By mixing or reacting with a metal compound and using a mixture with clay, color development performance,
It was possible to significantly improve the light resistance and sharpness of the colored image, to improve the yellowing resistance to light and yellowing caused by nitrogen oxides on the printed surface, and to improve the resistance to fading caused by plasticizers. Hereinafter, the present invention will be described in detail and specifically. The color developer ink for pressure-sensitive copying paper of the present invention is mainly composed of four components: a color developer, a pigment, a binder, and an organic solvent. First, p-substituted alkylphenols, which are raw materials for forming the color developer that characterizes the present invention,
The conditions that define the reaction product, such as the molar ratio of the P-substituted alkylphenol and p-hydroxybenzoic acid, the formaldehyde source, and the polyvalent metal compound, will be specifically exemplified below. As p-alkylphenol species, substituents are
C ₁ to C ₁₂ (e.g. p-cresol, p-
(ethylphenol, p-isopropylphenol, p-tert-butylphenol, p-tert-amylphenol, p-tert-octylphenol), preferably _C4 to _C12 . The desired condensate can be obtained by reacting one or more of the above p-substituted alkylphenols in the presence of p-hydroxybenzoic acid. The molar ratio of p-hydroxybenzoic acid and p-substituted alkylphenol used is p-
Hydroxybenzoic acid/p-substituted alkylphenol=0.1-5, preferably 0.5-3. As the formaldehyde source, any formaldehyde source such as formalin and paraformaldehyde can be used as long as it generates formaldehyde under the reaction conditions.
Examples of the catalyst include phosphoric acid, hydrochloric acid, oxalic acid, p-toluenesulfonic acid, and sulfuric acid. The molar ratio of formaldehyde/[p-substituted alkylphenol + p-hydroxybenzoic acid] is usually
It is 0.4-1, preferably 0.6-0.8. Polyvalent metal compounds include oxides, hydroxides, carbonates, basic carbonates, phosphates, silicates or sulfates of zinc, aluminum, titanium, nickel, cobalt, magnesium or calcium; Zinc is particularly preferred as the metal, and as compounds include oxides, hydroxides, basic carbonates,
In particular, oxides are preferred. The ratio of the polyvalent metal compound and condensate is usually 1:99 to 99:99 by weight.
Although the ratio is appropriately selected from the range of 1, 5:95 to 80:20 is preferable in consideration of the flatness of the resulting copy paper and economical efficiency. When reacting polyvalent metal compounds, the reaction temperature is room temperature or higher and 240°C or lower, preferably 80 to 180°C.
It is. Examples of clays include those having color developing ability, such as kaolin, acid clay, and activated clay. In addition,
These can also be utilized as pigments as described below. Pigments include oxides such as titanium oxide, zinc oxide, magnesium oxide, aluminum oxide, and silicon oxide, hydroxides such as zinc hydroxide and magnesium hydroxide, carbonates such as magnesium carbonate and calcium carbonate, kaolin, and acid clay. Examples include clays such as. Incidentally, the pigment is related to the proper improvement during printing, regardless of the presence or absence of color developing ability. As a binder, nitrocellulose, acetylcellulose, acetylbutylcellulose, ethylcellulose, benzylcellulose, cyanocellulose, hydroxyethylcellulose, methylcellulose, hydroxypropylcellulose, vinyl chloride resin, vinyl acetate resin, vinyl chloride/vinyl acetate resin, vinylidene chloride resin , vinylidene chloride/vinyl chloride resin, vinylidene chloride/acrylonitrile resin, polyvinyl acetoacetal resin, polyvinyl butyral resin, polyvinyl methyl ether resin, acrylic resin, modified acrylic resin, polyester resin, polystyrene, α-methyl polystyrene, styrene-α-methyl Resins such as styrene resin, ethylene-maleic anhydride,
Examples include copolymers of isobutylene-maleic anhydride, styrene-maleic anhydride, acetic acid-maleic anhydride, methyl vinyl ether-maleic anhydride, and the like. Examples of organic solvents include ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, esters such as methyl acetate and ethyl acetate, aromatics such as toluene and xylene, alcohols such as methanol, ethanol, and propanol, and ether of ethylene glycol. , ester, etc. Hereinafter, the present invention will be specifically explained with reference to Examples. In the examples, "parts" indicate parts by weight. Example 1 (1) Synthesis of color developer 69 parts of p-hydroxybenzoic acid, 138 parts of p-tert-octylphenol, 61.5 parts of 37% formalin
1 part, p-toluenesulfonic acid, and 53 parts of water were placed in a reaction vessel, and after reacting under reflux for 3 hours, 21 parts of transparent zinc white was added, and after the reaction under reflux for another hour, the condensate was taken out. Solidified. This condensate is made into an average particle size of 2 to 3μ by a dry grinder,
It was used in the following experiment. (2) Preparation of color developer ink for flexo/gravure Color developer obtained in (1) above 10 parts Titanium oxide 10 parts Acrylic resin 2.5 parts Methyl ethyl ketone/ethanol (2:1)
33 parts Example 2 Creation of color developing ink for flexo/gravure Color developer obtained in Example 1 (1) 10 parts Kaolin 5 parts Titanium oxide 5 parts Acrylic resin 2.5 parts Methyl ethyl ketone/ethanol (2:1) 33 Part Comparative Example 1 Preparation of color developer ink for flexo/gravure p-phenyl-phenol 10 parts Titanium oxide 10 parts Acrylic resin 2.5 parts Methyl ethyl ketone/ethanol (2:1) 33 parts Comparative Example 2 Preparation of color developer ink for flexo/gravure Preparation p-phenyl-phenol 10 parts Kaolin 5 parts Titanium oxide 5 parts Acrylic resin 2.5 parts Methyl ethyl ketone/ethanol (2:1) 33 parts Below, the color developing inks prepared in Examples 1 and 2 and Comparative Examples 1 and 2 were used. A developer sheet was obtained by printing on 41 g/m ² high-quality paper by flexographic printing so that the amount of smearing (solid content) was about 3 g/m ² . The test methods and evaluation results (Table 1) of various tests on the obtained color developing sheet are shown. (1) Color development test Commercially available pressure-sensitive recording paper "Mitsubishi NCR Paper-40" was layered with a color developer sheet and passed through a super calendar at a pressure of 10 kg/cm ² to develop color.
After 24 hours, the color density was measured using an optical densitometer with a red filter. Note that the higher the numerical value, the greater the color density. (2) Light resistance test The colored sample obtained in (1) above was irradiated with xenon light for 3 hours using a fade meter, and the density after fading was measured in the same manner. Note that the higher the numerical value, the greater the light resistance. (3) Plasticizer resistance test The colored sample obtained in (1) above was
0.2mm) bag and heated and stored at 60℃ for 1 day and night.
After contacting with a plasticizer contained in vinyl chloride, the blue color density was measured using an optical densitometer with a red filter. Note that the higher the value, the greater the plasticizer resistance. (4) Light yellowing test of uncolored area Irradiated with xenon light for 3 hours in the same way as in (2) above,
Yellowing density was measured using an optical densitometer with a blue filter. The higher the value, the more progressed the yellowing, and the lower the value, the better. (5) Yellowing resistance test due to nitrogen oxides The uncolored developing sheet was left in a container containing 150 ppm nitrogen oxides for 30 minutes, and then the yellow density was measured using an optical densitometer with a blue filter. The higher the value, the more progressed the yellowing, and the lower the value, the better. The uncolored density is also listed in Table 1 for comparison with yellowing resistance.

[Table] As shown in Table 1, the color developer ink for flexo/gravure of the present invention has better color development, light resistance, plasticizer resistance, and light resistance of uncolored areas compared to the color developer ink shown in the comparative example. It is clear that it has remarkable properties in yellowing and yellowing due to nitrogen oxides.

Claims (1)

[Scope of Claims] 1. A color developer ink for pressure-sensitive copying paper mainly comprising an electron-accepting color developer, a pigment, a binder, and an organic solvent, wherein the color developer contains p-hydroxybenzoic acid and a carbon atom having 1 carbon atom. A reaction product obtained by mixing or reacting a condensate obtained by reacting a p-substituted alkylphenol having ~12 alkyl groups with formaldehyde in the presence of an acidic catalyst with a polyvalent metal compound. Color developing ink for flexo and gravure. 2. In a color developer ink for pressure-sensitive copying paper mainly consisting of an electron-accepting color developer, a pigment, a binder, and an organic solvent, the color developer contains p-hydroxybenzoic acid and an alkyl group having 1 to 12 carbon atoms. A flexo compound comprising: mixing or reacting a condensate obtained by reacting a p-substituted alkylphenol with formaldehyde in the presence of an acidic catalyst with a polyvalent metal compound, and mixing with a clay.・
Color developing ink for gravure.