JPS6311995B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a carbonless copying paper with significantly improved color stability. Carbonless copy paper is well known, for example, US Pat. No. 2,712,507, US Pat.
Microcapsules containing an organic solvent solution of a colorless organic compound (hereinafter referred to as a coloring agent) having electron-donating properties, adsorption properties, and color-forming reactivity, as described in the specification of No. 2800458, etc., and electron-accepting microcapsules. This method utilizes a highly reactive and adsorbent substance (hereinafter referred to as a color developer). Conventionally, microencapsulation methods have been carried out by coacervation method, interfacial polymerization method, in-situ method, etc. Coloring agents include malachite green lactone, crystal violet lactone, benzoyl leucomethylene blue, rhodamine B lactam, 3-dialkylamino-7
-Dialkyl amylfluorane, 3-methyl-
2,2-spiropy(benzo-[f]-chromene), etc. are used, and as the color developer, inorganic solid acids such as acid clay, activated clay, attapulgite, zeolite, and bentonite are generally used. , phenolic resins such as paratertiary butylphenol resin, paraphenylphenol resin, and paraoctylphenol resin, or organic acid compounds such as succinic acid, tannic acid, malonic acid, maleic acid, and gallic acid, as well as benzoic acid, salicylic acid, and substituted There is a method using aromatic carboxylic acids such as salicylic acid, naphthoic acid, and diphenic acid, or metal compounds thereof. In general, a color forming agent and a color developer are applied to the same side, opposite sides, or different sides of a support, and the color forming agent in the microcapsule is released by writing pressure or hammering pressure, and when it comes into contact with the color developer, it develops a color. Records can be obtained according to pressure. As mentioned above, various color developers are known, but when currently widely used clays, such as activated clay and acid clay, are used as color developers,
The disadvantage was that the light resistance, moisture resistance, and hue stability after color recording were insufficient. To address these shortcomings, Japanese Patent Application Publication Nos. 48-33919, 52-106907, and 55
Improvements have been made by including metal compounds described in Publication No. -53593 and the like. Furthermore, metal compounds described in Japanese Patent Application Laid-Open Nos. 54-62826 and 54-65185 are used to improve the light resistance of organic dyes. The present invention aims to significantly improve the above-mentioned drawbacks. Therefore, the main object of the present invention is to improve the light fastness and moisture fastness of a color-forming recorded image composed of a color former and a color developer,
The aim is to stabilize the crystal violet lactone color former, which is a primary color former, and the benzoyl leucomethylene blue color former, which is a secondary color former, and to further stabilize the hue. The object of the present invention is to provide carbonless copying paper using activated clay or acid clay as a color developer and a primary color former such as crystal violet lactone and a secondary color former such as benzoyl leucomethylene blue as color formers. was achieved by using at least one type of dithiocarbamate metal salt represented by the following general formula (). (In the formula, n = 2 or 4, R ₁ and R ₂ represent a C ₁ to C ₄ alkyl group or a phenyl group, M is Co, Ni,
Represents one type of polyvalent metal selected from the group consisting of Cu, Zn, Te, Pd, and Mg. Although these metal complexes are known as stabilizers, it is completely unknown that they can be used in carbonless copying paper to achieve the above purpose. Furthermore, it exhibits more remarkable effects than known ultraviolet absorbers, antioxidants, deterioration inhibitors, and the like. Particularly, remarkable effects were shown by containing this compound in the color developer layer. Metal complexes falling within the range of the general formula () that are particularly effective in carrying out the present invention are exemplified in Table 1 below, but the present invention is not limited to these compounds.

[Table] Among the clay minerals used as a color developer in the present invention, clay minerals such as montmorillonite, attapulgite, and bentonite are preferred, and montmorillonite-type clay minerals are particularly preferred. Montmorillonite type clay minerals are clay minerals such as acid clay and activated clay obtained by acid treatment. In particular, as activated clay, there are
As described in Publications No. 41-7622 and No. 42-8811, acid clay is treated with mineral acid to elute acid-soluble alumina, iron, and other basic components, and to increase its specific surface area. There are some with a density of 200m ² /g or more.
Activated clay is also amorphous when observed with X-rays, has a large specific surface area, and has properties significantly different from those of pigments used for coating general paper. The appropriate amount of acid clay or activated clay used as a color developer is about 3 g to 8 g per 1 m ² of carbonless copying paper. Furthermore, electron-donating colorless organic compounds as color formers (e.g. crystal violet lactone,
The amount of primary and secondary color forming agents (such as benzoyl leucomethylene blue) used is 1 for carbonless copying paper.
Approximately 30 mg to 400 mg per m ² is appropriate. On the other hand, when the compound () is included in the color developer layer, the present invention is achieved by particularly preferably containing 0.1 part to 10 parts per 100 parts by weight of activated clay or acid clay. Ru. The case where it is contained in the color developer layer will be described below. The above-mentioned compounds (2) are wet-pulverized in advance using a crusher such as a ball mill, a Kedi mill, an attritor, a sand mill, or a colloid mill. At that time, increase the solid content concentration to 20~
It is desirable that the average particle size be 40% and the average particle size be about 5μ. The wet-pulverized product of the compound () contains a dispersant, activated clay or acid clay, a water-soluble binder, a latex binder and other clays,
When preparing a color developer coating solution composed of additives, etc., the additives may be added in any order, but it is preferable to add them before adding the latex binder. When preparing the coating solution, stable dispersion can be achieved by using a low-molecular or high-molecular dispersant or surfactant having an anionic group such as phosphoric acid, sulfonic acid, or carboxylic acid or a nonionic group such as hydroxyl group. Liquids can be prepared in a short time. Also, metal compounds such as oxides, hydroxides, silicates or carbonates of metals selected from the group of aluminum, calcium, magnesium, titanium, nickel, cobalt, manganese, iron, tin, copper, vanadium and chromium. may be used together. Furthermore, a water-soluble polyvalent metal salt may also be used in combination. These are in particular water-soluble salts of polyvalent metals such as zinc, aluminum, calcium, magnesium, etc., especially salts with strong acids. Furthermore, a binder is generally used in preparing the developer coating solution. Water-soluble binders include water-soluble natural polymer compounds such as protein, starch, and cellulose; water-soluble synthetic polymer compounds such as polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic acid, polyacrylamide, maleic acid copolymers, etc. There is. Examples of latex binders include styrene-butadiene latex, acrylonitrile-butadiene latex, acrylic ester latex, vinyl acetate latex, methyl methacrylate-butadiene latex, and carboxy-modified latexes thereof. These water-soluble binders and latex-based binders are used in combination depending on the preparation of the coating solution, coating conditions, and characteristics of the carbonless copying paper (such as color development ability). Preferably, carboxy-modified SBR latex is used. In addition to inorganic solid acid color developers such as acid clay and activated clay, clays, phenols,
Organic acids such as phenolic resin, aromatic carboxylic acid, aliphatic polycarboxylic acid, etc. may be used in combination. The coating liquid can be applied using, for example, air knife coating, blade coating, roll coating, curtain coating, or the like. In the present invention, any method known to those skilled in the art can be applied without being limited to the method for preparing a coating solution using acid clay or activated clay, coating method, etc. Examples of the present invention will be described below.
It is not limited to these. Example 1 0.5 parts of sodium hexametaphosphate as a dispersant was dissolved in 150 parts of water (abbreviated as parts by weight or less), and a 10% aqueous solution of polyvinyl alcohol (PVA105 manufactured by Kuraray Co., Ltd.) was separately heated and dissolved therein. Add 60 parts. To this system, 100 parts of Silton clay (activated clay for carbonless paper manufactured by Mizusawa Kagaku Co., Ltd.) is added with stirring and thoroughly dispersed. Separately, 15 parts of the above-mentioned dithiocarbamate compound I-3, which had been pulverized in a ball mill at a concentration of 40% to an average particle size of about 5μ, was added and mixed, and SBR latex (Dow manufactured by Asahi Dow Co., Ltd.) was mixed.
-670 (solid content: 48%) was added, and the pH was adjusted to 9.5 with a 20% caustic soda solution to obtain a color developer coating solution.
This coating liquid was applied to a base paper having a basis weight of 40 g/m ² using an air knife coater so that the coating amount was 8 g/m ² (solid content) and dried to obtain the color developing paper of Example 1. Example 2 Dithiocarbamate compound I-3 of Example 1
A developer coating solution prepared in the same manner as in Example 1 using 1 part of dithiocarbamate compound I-5 similarly ground at 40% concentration instead of was applied using an air knife coater in the same manner. A developer paper of Example 2 was obtained. Comparative Example 1 0.5 parts of sodium hexametaphosphate as a dispersant was dissolved in 150 parts of water, and polyvinyl alcohol (PVA105 manufactured by Kuraray Co., Ltd.) was separately heated and dissolved therein.
Add 60 parts of a 10% aqueous solution of Silton clay (Mizusawa Chemical Co., Ltd. activated clay for carbonless paper) is used in this system.
Add 100 parts with stirring and disperse well.
Furthermore, 20 parts of SBR latex (Dow-670 manufactured by Asahi Dow Co., Ltd., solid content 48%) was added, and a 20% caustic soda solution was added.
A developer coating solution was obtained by adjusting the pH to 9.5. This coating liquid was applied to a base paper with a basis weight of 40 g/m ² using an air knife coater in the same manner as in Examples 1 and 2 to a coating amount of 8 g/m ² (solid content).
A color developer paper for comparison was obtained by smearing and drying so as to obtain the following. Comparative Example 2 0.5 parts of sodium hexametaphosphate as a dispersant was dissolved in 150 parts of water, and polyvinyl alcohol (PVA105 manufactured by Kuraray Co., Ltd.) was separately heated and dissolved therein.
Add 60 parts of a 10% aqueous solution of Silton clay (Mizusawa Chemical Co., Ltd. activated clay for carbonless paper) is used in this system.
Add 100 parts with stirring and disperse well. In addition to this, the average particle size was adjusted to 40% using a ball mill.
Add and mix 15 parts of 2-hydroxy-4-octoxybenzophenone (benzophenone antioxidant) crushed to about 5μ, and further add SBR latex (Dow-670 manufactured by Asahi Dow Co., Ltd. solid content 48%). A developer coating solution was obtained by adding 20 parts and adjusting the pH to 9.5 with a 20% caustic soda solution. This coating liquid was coated with an air knife coater in the same manner as in Examples 1 and 2 and Comparative Example 1 to give a basis weight of 40 g/m ^{2 .}
A color developing paper for comparison was obtained by smearing and drying the mixture on a base paper so that the amount of smearing was 8 g/m ² (solid content). (As the coloring agent sheet, a commercially available top paper for carbonless copying paper "Mitsubishi NCR Paper-40 (blue coloring)" was used.) [Color development method]: Top paper was obtained in Examples 1 and 2 and Comparative Example. The mixture was placed on developer paper and passed through a super calendar at a pressure of 400 kg/cm ² to develop color. [Measurement method after color development]: One hour after color development, reflectance was measured using a ND-101D color difference meter manufactured by Nippon Denshoku Co., Ltd., and the degree of color development was calculated using the following formula. It was expressed as the degree of color development. Coloring degree (%) = Reflectance of colored paper/Reflectance of white paper x
100 [Weather resistance after color development]: After 2 hours of exposure to sunlight after super calendar color development or humidification at 40℃90%RH
(Relative Humidity) The reflectance after 24 hours of treatment was measured using the color difference meter, and the degree of color development was determined. The smaller the numerical values listed in Table 2 below, the higher the concentration.

[Table] As shown in the table above, the degree of color development without treatment is not much different between the Examples and Comparative Examples, but the degree of color development after sunlight or humidification treatment is significantly improved in both Examples 1 and 2 compared to the Comparative Example. . In addition to the above examples, samples were prepared using other compounds shown in Table 1. Color was developed in the same manner as above, and then sunlight or humidification treatment was performed. As a result, the hues of the colored images of all the samples showed almost no change and showed good weather resistance. In particular, Example 2 exhibited little change in hue, retaining the violet hue caused by the ring opening of crystal violet lactone, and clearly exhibited superiority in terms of hue stabilization.

Claims (1)

[Scope of Claims] 1. A carbonless copying paper using activated clay or acid clay as a color developer and an electron-donating colorless organic compound as a color former, containing a compound represented by the following general formula (). Carbonless copy paper featuring (In the formula, n = 2 or 4, R ₁ and R ₂ represent a C ₁ to C ₄ alkyl group or a phenyl group, M is Co, Ni,
Represents one type of polyvalent metal selected from the group consisting of Cu, Zn, Te, Pd, and Mg. ) 2 The compound represented by the general formula () is used in the color developer layer and is 0.1 per 100 parts by weight of activated clay or acid clay.
The carbonless copying paper according to claim 1, characterized in that it contains from 1 part to 10 parts.