JPH0326152B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a color developer printing ink for pressure-sensitive copying paper, and particularly to a color developer printing ink suitable for letterpress and planographic printing. Pressure-sensitive copying paper utilizes a color-forming reaction between a colorless electron-donating color-forming organic compound and an electron-accepting color-developing substance. Usually, the electron-donating color-forming organic compound is dissolved in a solvent. It is made by applying a microencapsulated coating liquid to the back side of a base paper, and then applying an electron-accepting color developing substance to the surface of the base paper. Since ordinary pressure-sensitive copying paper is coated on both the front and back sides of the base sheet, special ink that prevents color reaction must be desensitized in areas that do not require copying. For this reason, a method has been proposed in which a microencapsulated color-forming compound or color-developing substance is printed only on the areas that require copying. Some methods of partially printing on the surface have been put into practical use. However, such developer inks use organic solvents with low boiling points, which pose not only toxicity and fire hazards, but also the disadvantage that they are unsuitable for the more common letterpress and platelet printing processes. On the other hand, color-developing printing inks that can be used in letterpress and lithographic printing have also been developed (for example,
No. 68307, No. 51-80410, No. 51-94308, No. 54
−89816, No. 54-94910, No. 54-55163, No.
55-38826 and 55-71588). However, all of these types of color developer printing inks cause rubber rollers to swell, lack printability and make long-term continuous printing impossible, prints develop short colors during storage, and color development ability deteriorates over time. At present, it has not been put into practical use due to drawbacks such as poor printing performance and poor printing durability. The present invention solves all of the above-mentioned drawbacks and provides a color developing printing ink for pressure-sensitive copying paper that is capable of letterpress or lithographic printing. weight ratio
₂₀ to 60 wt. 80 to 40% by weight of silicate ester represented by
It is contained in the color developing printing ink. Phenolic hydroxyl group-containing compounds useful in the present invention include p-phenylphenol formaldehyde polycondensate, p-nitrophenol formaldehyde polycondensate, p-carboxyphenol polycondensate, 5-t-butylsalicylic acid, 3-phenyl Salicylic acid, 3-methyl-5-t-butylsalicylic acid, 5-hexylsalicylic acid, 5-nonylsalicylic acid, 3-chloro-4-t-butylsalicylic acid,
2-Hydroxy-3-methylbenzoic acid, 2,4-
Dihydroxysalicylic acid, 1-hydroxy-2-
Examples include naphthoic acid, salicylic acid formaldehyde polycondensate, metal salts thereof (particularly zinc salts), and arbitrary mixtures thereof. The purpose of using fatty acid amide in the present invention is to
Increases the dissolving power of the phenolic hydroxyl group-containing compound (color developing substance) to the silicate ester (ink solvent), making the coloring ability more effective. Fatty acid amides useful in the present invention include primary amides, secondary amides, tertiary amides of fatty acids, substituted derivatives thereof, and any mixtures thereof, including caproic acid amide, caprylic acid amide, caprylic acid N
- Methylamide, capric acid amide, capric acid N-methylamide, lauric acid amide, lauric acid dodecylamide, myristic acid amide, myristic acid ethylamide, stearic acid amide, stearic acid N-octylamide, arginic acid amide, behenic acid amide, olein Examples include acid amides, and any mixtures thereof. In the present invention, a silicate ester is used as an ink solvent. Conventional ink solvents have some drawbacks, which are completely eliminated by using silicate esters. For example, linseed oil has a desensitizing component, which prevents the ink from developing color over time. Glycol solvents have a similar tendency. kerosene,
Petroleum-based solvents such as diesel oil swell rubber, causing printed matter to develop a short color while being stored. When a silicate ester is used, there is no such drawback. In addition, examples of silicic acid esters useful in the present invention include tetraoctyl silicate, tetranonyl silicate, tetradecyl silicate, tetraundecyl silicate, tetradidecyl silicate, tetratridecyl silicate, tetratetradecyl silicate, tetrapentadecyl silicate, tetrahexadecyl silicate, and silicic acid. Examples include tetrapentadecyl, tetraoctadecyl silicate, tetranonadecyl silicate, and any mixture thereof, and silicic acid esters in which R in the general formula is an alkyl group having 11 to 13 carbon atoms, that is, tetraundecyl silicate,
Tetradidecyl silicate, tetratridecyl silicate, and the like are particularly preferred in terms of ink physical properties and color print resistance. The blending ratio (weight ratio) of the above phenolic hydroxyl group-containing compound and fatty acid amide is 30:1 to 30:30,
Preferably it is 30:4 to 30:10, and this blending ratio is 30:
Becomes greater than 1. That is, when the amount of fatty acid amide is less than this ratio, the solubility of the phenolic hydroxyl group-containing compound in the silicate ester becomes poor, and when this blending ratio is less than 30:30, that is, the amount of fatty acid amide is greater than this ratio. In this case, the viscosity of the printing ink becomes high, which causes problems in printability. A mixture of the phenolic hydroxyl group-containing compound and the fatty acid amide having such a mixing ratio is dissolved in the silicate ester at a ratio of 20 to 60% by weight, preferably 20 to 40% by weight. If the amount of the mixture is less than 20% by weight, the color development of the ink will deteriorate;
If it exceeds this, printability will be extremely poor. The color developing printing ink of the present invention contains conventional additives, such as color development aids such as zinc oxide and zinc chloride, as well as gelling agents (aluminum stearate, etc.).
etc. may be blended as appropriate. When the color-developing printing ink of the present invention is used in pressure-sensitive copying paper, the corresponding color-forming component is not particularly limited, and may be an electron-donating color-forming organic compound conventionally used in pressure-sensitive copying paper. They may be appropriately selected from among them, microencapsulated by a conventional method, and used. The manner in which the printing ink for color development according to the present invention is used is not particularly limited, but for example, as shown in the schematic vertical cross-sectional view of a three-sheet set in FIG. is applied as is, the second sheet is a printing ink layer 2 for color development on the surface of the upper paper 1 of pressure-sensitive copying paper and used as the inner paper, and the third sheet is a color developer on the surface of general paper 3 such as high-quality paper. It is used in an embodiment in which a printing ink layer 2 is provided. As described above, the present invention provides a novel color developer obtained by using a silicate ester represented by the above general formula as an ink solvent and dissolving a color developer phenolic hydroxyl group-containing compound therein via a fatty acid amide. The printing ink has excellent printability, color development, light fastness, water resistance, chemical resistance, etc., and effectively solves the aforementioned problems related to pressure-sensitive copying paper. The present invention will be explained below using Examples and Comparative Examples. Example 1 A color developing printing ink for pressure-sensitive copying paper was prepared by homogenizing a mixture according to the following formulation at 130 to 140°C. Ingredient parts by weight: Tetradidecyl silicate 50 Palmitic acid amide 7 p-Nitrophenol formaldehyde polycondensate 43 Example 2 Silton clay (manufactured by Mizusawa Chemical Industry Co., Ltd.) was added to the varnish obtained by homogenizing the mixture according to the following formulation at 130 to 140°C. A color developer printing ink for pressure-sensitive copying paper was prepared by adding 5 parts by weight of clay and kneading it with three rolls. Ingredient parts by weight 3-Methyl-5-t-butylsalicylate Zinc 30 Zinc chloride 2 Stearic acid amide 5 Tetratridecyl silicate 50 Example 3 The printing inks obtained in Examples 1 and 2 or the RI tester (Mei Seisakusho Co., Ltd.) The color was spread uniformly on the surface of pressure-sensitive copying paper using a
^m2 ) The following tests were conducted on the test sheet. 1. Color development ability: combine the colored materials into a set of 6,
I copied it on a typewriter and checked its coloring ability. 2 Storage life: Combine the color exhibits into a set of 3, 50
Pressure treated at ℃ for 5 hours and 10 hours (100
g/m ² ), shoot color development, and contact contamination. 3 Resistance (a) Light resistance: test sheet with fade meter
5 hours and 8 hours. (b) Water resistance: The test sheet was immersed in clean water at 25°C for 1 hour. (c) Acid resistance: The test sheet was immersed in a 4% acetic acid aqueous solution at 25°C for 1 hour. (d) Alkali resistance: The test sheet was immersed in 4% ammonia water at 25°C for 1 hour. The results of the above test are shown in Table-1. Comparative Example 1 (Example described in JP-A-51-68307) 10 parts by weight of zinc oxide and 10 parts by weight of methane oxide were added to a varnish prepared by homogenizing the mixture according to the following formulation at 130 to 140°C, and three A printing ink for color development was prepared by kneading using a roll. Ingredient weight parts 3,5-di-t-butylsalicylic acid zinc 10 Ester gum ¹⁾ 4 Ink solvent #3 ²⁾ 15 1) AA-L manufactured by Arakawa Chemical Co., Ltd. 2) Comparative example 2 manufactured by Nippon Oil Co., Ltd. In comparative example 1 A test sheet was prepared in the same manner as in Example 3 using the obtained printing ink, and the same tests as in Example 3 were conducted on this test sheet. The test results are shown in Table-1.

【table】

[Table] No)

[Brief explanation of the drawing]

FIG. 1 is a schematic longitudinal sectional view of pressure-sensitive copying paper using the color developing printing ink according to the present invention. Reference numeral 1 indicates top-sheet paper, 2 indicates a printing ink layer for color development, and 3 indicates general high-quality paper.

Claims (1)

[Claims] 1. A mixture containing a phenolic hydroxyl group-containing compound and a fatty acid amide in a weight ratio of 30:1 to 30:30.
A printing ink for color development containing 80 to 40% by weight of a silicate ester represented by weight percent and general formula: Si(OR) ₄ (in the formula, R represents an alkyl group having 8 to 19 carbon atoms). 2. The printing ink according to item 1, wherein the silicate ester is tetraundecyl silicate, tetradidecyl silicate, or tetratridecyl silicate.