JPS6344076B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a color developing ink. For more details,
This invention relates to a developing ink for flexo or gravure printing that has improved color development, light resistance, yellowing resistance, and plasticizer resistance. In general, pressure-sensitive copying paper is coated with fine capsules containing an electron-donating colorless or light-colored leuco dye dissolved in an organic solvent (capsule oil) on the back side, and an electron-accepting color developer on the front side. By stacking these two types of coated surfaces facing each other and applying pressure with a ballpoint pen or typewriter, the capsule in the pressure area is destroyed and the leuco dye is released. Capsule oil contained therein is transferred to the color developing layer and undergoes a coloring reaction, thereby making it possible to obtain printed records. In addition, if inner paper coated with a developer layer on the front side and capsules containing leuco dye on the back side is used by sandwiching it between the upper paper and the lower paper, a large number of copies can be obtained. When this pressure-sensitive copying paper is used for forms such as business forms, there are some areas where copying is not necessary due to the layout. For areas that do not require copying, a method is used to completely print desensitized ink to eliminate the coloring ability, but this is very uneconomical, so color developer is applied solidly only to areas that require copying. Printing is performed, and developing inks are commercially available for this purpose. Color developing ink is usually made by dissolving or dispersing a color developer in an organic solvent and adding pigments, binders, etc., and is printed on the surface of base paper using flexo or gravure methods and then placed under a spot. It can be printed on paper or on the surface of upper paper and used as spot paper. Generally, a color developer ink for flexographic or gravure printing is composed of a color developer, a pigment, a binder, and an organic solvent, and is obtained by adding the pigment, binder, etc. to a color developer dissolved or dispersed in an organic solvent. During printing, the viscosity of the ink is adjusted by diluting the ink by adding an organic solvent. Conventionally known color developers include acid clay disclosed in USP 2712507, inorganic solid acids such as attapulgite, substituted phenols and diphenols disclosed in Japanese Patent Publication No. 40-9309, and Japanese Patent Publication No. 42-20144. There are P-substituted phenol formaldehyde polymers and aromatic carboxylic acid metal salts disclosed in Japanese Patent Publication No. 49-10856, etc., but P-substituted phenol formaldehyde polymers are currently used as color developers in color developing inks. is the main subject. However, these color-developing inks have insufficient color-forming ability, and when exposed to sunlight or fluorescent light, the colored images tend to fade or the background turns yellow, and they cannot be stored between sheets of vinyl chloride film. if you did this,
There is a drawback that the colored image is erased by the plasticizer in the film. Furthermore, since this type of color developing ink uses a solvent, the working environment in a printing shop is poor, so there is a desire to develop an ink that uses a non-toxic solvent. Generally, solvents for flexo or gravure printing include methyl alcohol, ethyl alcohol, n
- Alcohols such as propyl alcohol, isopropyl alcohol, n-butyl alcohol, glycols such as ethylene glycol and propylene glycol, cellosolves such as methyl cellosolve and ethyl cellosolve, esters such as ethyl acetate and butyl acetate, n-hexane , aliphatic hydrocarbons such as cyclohexane, aromatic hydrocarbons such as benzene and toluene, and ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone. Among these solvents, methyl alcohol, isopropyl alcohol, ethyl acetate, and butyl acetate are mainly used in conventional color developing inks, but these solvents have the disadvantage of being toxic or having a strong odor, which worsens the working environment. On the other hand, ethyl alcohol requires the installation of a general ventilation system or local exhaust ventilation system, the use of protective equipment, the appointment of an organic solvent work chief, and the measurement of organic solvent concentration in the working environment, according to the Organic Solvent Poisoning Prevention Regulations of the Industrial Safety and Health Act. It is desirable to use ethyl alcohol as the organic solvent because there are no regulations and the odor is weak. On the other hand, the developer ink is applied by a flexo or gravure printing machine, unlike the developer layer of the lower paper, which is applied by a coater, so the amount of application is 2 to 3.
g/m ² , which is very small. Therefore, in order to cause the color developer to undergo a color-forming reaction efficiently, it is desirable to use an organic solvent in which the color developer can be completely dissolved. Conventionally, P-phenylphenol formaldehyde polymer, which has been used as a color developer, is combined with ethyl acetate, which has good solubility, to increase color development efficiency. If non-toxic ethyl alcohol is used as the color developer, the ink will have poor solubility and will be in a dispersed state, and a color developer sheet coated with this ink will have extremely low color development performance, making it impractical. In addition, as a binder, it not only adhesively fixes pigments, but also firmly adheres to the fine color developer crystals that precipitate after the solvent evaporates, and does not impair discoloration and does not change in quality due to light, temperature, or humidity. You need to choose one that will not discolor. In this case, even if the binder itself does not cause any deterioration or discoloration, depending on the combination with the color developer, it may be susceptible to deterioration or discoloration due to the activity of the color developer. The important point is to carefully consider the properties of both when selecting. In order to improve these drawbacks, the present inventors conducted research on various color developers, binders, and solvents and found that they had good color development, light resistance, yellowing, and
We were able to develop a color developing ink for flexo or gravure printing that has excellent plasticizer resistance and is non-toxic. In the present invention, as a color developer, the general formula: (In the formula, R represents hydrogen, halogen, _C1-12 alkyl group, cycloalkyl group, _C7-11 aralkyl group, or phenyl group, and M represents magnesium, calcium, zinc, titanium, manganese, iron, nickel. , cobalt, copper, and tin.) One or more metal salts of 2,2'-bisphenolsulfone compounds are used. The color developer ink of the present invention uses one type selected from Sierra resin and ketone resin as a binder for adhesively fixing the color developer and the pigment. Further, as the organic solvent, it is desirable to use ethyl alcohol as described above. The color developer ink of the present invention contains one or two color developers represented by the above general formula in 100 parts by weight of an organic solvent.
After dissolving 20 to 60 parts by weight of the seeds and 20 to 5 parts by weight of Sierra Tsuk resin or ketone resin as a binder, 60 to 35 parts by weight of the pigment is added to the solution using a grinding machine such as an attritor or a sand grinder. Obtained in a dispersed manner. Pigments that can be used here include, for example, kaolin,
Bentonite, activated clay, silica gel, zinc oxide, zinc hydroxide, calcium carbonate, magnesium carbonate, aluminum hydroxide, aluminum oxide,
Examples include titanium oxide, but are not particularly limited. When the color developing ink of the present invention is printed on the surface of 40 g/m ² base paper or top paper using a flexo printing machine (manufactured by Miyakoshi) in an amount of 2 g/m ² and overlapped with the top paper to form a type color. The coloring speed is fast, clear colors are obtained, the colored images have excellent light resistance, and there is no yellowing, and the colored images do not fade even when stored in a high humidity environment when sandwiched between soft vinyl chloride films. Nakatsuta. The present invention will be explained below based on examples. Example 1 Sierrac resin in 100 parts by weight of ethyl alcohol
12 parts by weight of 2,2'-bis(P-t-
30 parts by weight of zinc (octylphenol) sulfone and 58 parts by weight of kaolin were added and treated in an attritor for 40 minutes to obtain a color developing ink. Example 2 A developing ink was obtained in the same manner as in Example 1 using the following formulation. 2,2'-bis(P-cumylphenol) sulfone zinc 30 parts by weight Kaolin 55 〃 Ketone resin 15 〃 Ethyl alcohol 100 〃 Example 3 A developing ink was prepared in the same manner as in Example 1 with the following formulation. I got it. 2,2'-bis(P-cumylphenol) sulfone nickel 30 parts by weight Kaolin 55 〃 Ketone resin 12 〃 Alcohol-soluble phenolic resin 3 〃 Ethyl alcohol 100 〃 Example 4 Same method as Example 1 with the following formulation A developing ink was obtained. 2,2'-bis(P-nonylphenol) sulfonic nickel 30 parts by weight Light calcium carbonate 55 〃 Sierrak resin 15 〃 Ethyl alcohol 100 〃 Example 5 A developing ink was prepared in the same manner as in Example 1 with the following formulation. I got it. 2,2'-bis(P-nonylphenol) sulfone nickel 15 parts by weight 2,2'-bis(P-cumylphenol) sulfone zinc 15 〃 Light calcium carbonate 55 〃 Ketone resin 15 〃 Ethyl alcohol 100 〃 Example 6 A developing ink was obtained by using the same weight part of eryl acetate instead of ethyl alcohol in Example 2. Comparative Example 1 A color developing ink was obtained in the same manner as in Example 1 using the following formulation. P-phenylphenol formaldehyde polymer
30 parts by weight Kaolin 55 Nitrocellulose 15 Ethyl acetate 100 Comparative Example 2 A developing ink was obtained in the same manner as in Example 1 using the following formulation. P-phenylphenol formaldehyde polymer
30 parts by weight Kaolin 55 Sierrak resin 15 Ethyl alcohol 100 Comparative Example 3 In place of the Sierrak resin in Comparative Example 2, the same weight part of ketone resin was used to obtain a color developing ink. Comparative Example 4 A developing ink was obtained by using the same weight part of 2,2'-bis(P-nonylphenol) sulfone nickel instead of the P-phenylphenol formaldehyde polymer in Comparative Example 1. Comparative Example 5 A developing ink was obtained in the same manner as in Example 1 using the following formulation. 2,2'-bis(P-t-octylphenol) sulfone zinc 30 parts by weight Kaolin 55 Alcohol-soluble phenolic resin 15 Ethyl alcohol 100 Comparative example 6 2,2'-Bis(P-t- A developing ink was obtained by using the same weight part of 2,2'-bis(P-cumylphenol)sulfonezinc instead of octylphenol)sulfonezinc. Comparative Example 7 A developing ink was obtained in the same manner as in Example 1 using the following formulation. 2,2'-bis(P-cumylphenol) sulfone nickel 30 parts by weight Kaolin 55 Hydroxypropyl cellulose 15 Ethyl cellulose 100 parts by weight Comparative Example 8 The same parts by weight of ethyl cellulose was used in place of the Sierrak resin in Example 4. I got a vivid orgasm. Comparative Example 9 A color developing ink was obtained by using the same weight part of polyvinyl butyral instead of the ketone resin in Example 5. Comparative Example 10 A color developing ink was obtained by using the same weight part of polyvinylethyl ether in place of the alcohol-soluble phenolic fat in Comparative Example 5. Comparative Example 11 A color developing ink was obtained in the same manner as in Example 1 using the following formulation. 2,2'-bis(P-phenylphenol) sulfone nickel 15 parts by weight 2,2'-bis(P-cumylphenol) sulfone zinc 15 parts by weight Light calcium carbonate 55 〃 N-methoxymethylated nylon 15 〃 Methyl Alcohol 100 parts by weight Comparative Example 12 A developing ink was obtained by using the same parts by weight of acrylic ester in place of the ketone resin in Example 2. Comparative Example 13 In place of the hydroxypropylcellulose in Comparative Example 7, the same weight part of styrene maleic anhydride ethyl half ester was used to obtain a color developing ink. Comparative Example 14 In place of the alcohol-soluble phenolic resin of Comparative Example 5, the same weight part of ethylene maleic anhydride ethyl half ester was used to obtain a color developing ink. Comparative Example 15 A developing ink was obtained in the same manner as in Example 1 using the following formulation. 2,2'-bis(P-nonylphenol)sulfone nickel 30 parts by weight Kaolin 55 〃 Rosin-modified maleic acid resin 15 〃 Ethyl alcohol 100 〃 Comparative example 16 The same parts by weight of resorcinol were used in place of the ketone resin in Example 2. A developing ink was obtained. The color developing inks obtained in Examples 1 to 6 and Comparative Examples 1 to 16 were tested for color density, yellowing, light resistance, and plasticity resistance by the following methods. (1) Color density: Overlap the surface coated with the color developer ink and Jujo paperback paper (NW40T), develop the color using a typewriter, and measure the reflectance after 24 hours using a Hunter reflectance meter (manufactured by Toyo Seiki) using an amber filter. did. Using the reflectances I ₀ and I ₁ before color development and 24 hours after color development, it was expressed as color development rate=I ₀ −I ₁ /I ₀ ×100 (%). The higher the color development rate, the better. (2) Yellowing: The uncolored developer ink coated surface was exposed to sunlight for 4 hours, and the degree of yellowing of the coated surface was evaluated. The less yellowing the coated surface has, the better. (3) Light resistance: The surface coated with the color developing ink developed by the method (1) was exposed to sunlight for 4 hours, and the degree of fading of the coated surface was evaluated. The less fading the better. (4) Plasticizer resistance: The surface coated with the color-developing ink developed using the method in (1) was brought into close contact with a soft vinyl chloride film containing a plasticizer (dioctyl phthalate), and the temperature was 40°C and the humidity was 90%. The samples were stored for 48 hours and changes in color density were evaluated. The smaller the change in color density, the better. The test results are shown in Table-1.

【table】

【table】

[Table] (Note) ○ indicates a commercially practical state.
△ indicates that the product can be used but is difficult to put into practical use commercially.
An x mark indicates that it is commercially impractical.
Examples 1 to 6 in Table 1 have high color density and excellent yellowing, light resistance, and plasticizer resistance, whereas the P-phenylphenol formaldehyde polymers of Comparative Examples 1 to 3 have high color density and excellent yellowing, light resistance, and plasticizer resistance. The colorant used as a coloring agent has a low color density, and has poor yellowing, light resistance, and plasticizer resistance. Comparative Examples 4 to 16 are color developing inks in which the color developer of the present invention is combined with a binder other than the present invention. Comparative Examples 4 to 6 and 16 have high color density but poor yellowing, and Comparative Examples 7 to 15 have insufficient color density and light resistance. From the above results, the superiority of the color developing ink according to the present invention is clear.

Claims (1)

[Scope of Claims] 1. A color developer ink for flexographic or gravure printing, which contains one or more color developers represented by the following general formula, a Sierrak resin or a ketone resin, and an organic solvent. (In the formula, R represents hydrogen, halogen, a _C1-12 alkyl group, a cycloalkyl group, a _C7-11 aralkyl group, or a phenyl group, and M represents magnesium, calcium, zinc, titanium, manganese, iron, or nickel. , which represents a polyvalent metal such as cobalt, copper, or tin.) 2. The color developing ink according to claim 1, characterized in that ethyl alcohol is used as the organic solvent.