JPH04193581A - Developing sheet for carbonless copy paper - Google Patents

Abstract

PURPOSE:To provide a developing sheet excellent in color forming properties and reduced in the contamination due to the transfer of desensitizing ink by using an org. developer as an electron acceptive developer and using carbon dioxide specified in a BET specific surface area, the ratio of the BET specific surface area and an average particle size, oil absorption and water absorption as pigment. CONSTITUTION:In a developing sheet for carbonless copy paper formed by providing a developer layer containing an electron acceptive org. developer, an adhesive and pigment as main components, calcium carbonate characterized by that a BET specific surface area is 25-55m/g, the ratio of BET specific surface area (m<2>/g)/average particle size (mum) is 5-110, oil absorption according to an Ogura method is 120ml/100g or more and water absorption is 1.8g/g or more is used as the pigment. Calcium carbonate is used in an amount of 5-100%, pref., 10-60% by wt. of the pigment solid of the developer layer. When the amount of calcium carbonate is below 5wt.%, effect is not substantially obtained. Since calcium carbonate has high water absorbability, it is pref. to use calcium carbonate in an amount of 60% or less by wt. of pigment in the case of the use in a high solid coating solution.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a color developer sheet for Makerbond copying paper, and more particularly to a color developer sheet for Makerbond copying paper that has excellent color development and is less prone to staining due to transfer of desensitizing ink.

[Conventional technology]

It has been known for a long time that a colored image is obtained through a contact reaction between an electron-donating, almost colorless organic compound (hereinafter referred to as a color former) and an electron-accepting solid acid (hereinafter referred to as a color developer). Examples of materials that specifically utilize this phenomenon include pressure-sensitive copying paper (e.g., U.S. Pat. Nos. 2,505,470 and 2,505
489 specification) and heat-sensitive recording paper (e.g., Special Publication No. 45-14)
Publication No. 039). In general, inorganic solid acids such as activated clay, acid clay, and attapulgide have been frequently used as color developers for Makerbon copying paper. However, these clay-based solid acids lack stability of colored images against moisture and light. For this reason, noholac type phenolic resins, salicylic acid derivatives and/or polyvalent metal salts thereof are currently used. In addition, recently, with the aim of improving the slow color development speed of conventional phenolic resin color developers and the somewhat poor water resistance of the colored characters of salicylic acid color developers,
Many salicylic acid resins and their polyvalent metal salts have been proposed as color developers. These color developers include polyvalent metal salts of co-condensed resins such as salicylic acid and α, α-dialkoxy p-xylene (JP-A-62-176875.62-
178387.62-178388.63-53092
．． 63-159082.63-160877),
A polyvalent metal salt of a resin obtained by reacting a styrene derivative with a salicylic acid derivative having an aromatic substituent (JP-A-63
-186729), polyvalent metal salts of resins obtained by reacting benzyl halides with salicylic acid derivatives having aromatic substituents (JP-A-63-254124)
, and other resin polyvalent metal salts described in JP-A No. 63-289017 are known. Furthermore, polyvalent metal salt compounds consisting of salicylic acids, rosins, and polyvalent metal compounds are also disclosed as color developers (Japanese Patent Laid-Open No. 2-563). Generally, these organic color developers are used as a color developer sheet that is uniformly applied to the entire surface of a support, but depending on the purpose of use of the manufacturer's bonded copy paper, there may be areas on the side of the color developer sheet that do not require recording. In such cases, a method of desensitizing the color developer sheet by applying desensitizing ink containing a desensitizing agent to that portion of the color developer sheet using a printing machine or the like is used. Desensitizers, which are the main materials for desensitizing inks, include amines, glycols, and nonionic surfactants. These desensitizers are liquid at room temperature and do not have drying or solidifying properties, so desensitizing inks have poor drying properties compared to ordinary printing inks. When the color developer sheet is desensitized and printed using a form printing machine or the like and then folded in a zigzag pattern, the developer surfaces face each other. At this time, there is a phenomenon in which the desensitizer applied to the desired specific area is transferred to the opposing desired area of the developer sheet and the desensitizing effect spreads to areas other than the required areas (hereinafter, this phenomenon is referred to as "desensitizing agent"). (referred to as "transfer stains caused by ink"). Concerning transfer stains of desensitizing ink, it is more likely to occur when an organic color developer is used than when an inorganic color developer is used, and in particular, the polyvalent metal salt of salicylic acid resin is Probably because it dissolves easily in the ink solvent, it had a tendency to cause transfer stains. As a result, the desensitizer transfers to the desired copy area, and even if you try to overlap the desired copy area with a manufacturer's bonded copy paper to produce color, the color density desired for copy may become weaker, or the color may hardly develop at all. There was. In order to solve this problem, the present inventors attempted to prevent transfer by absorbing the desensitizer into the pigment by applying a mixture of an organic color developer and a highly oil-absorbing pigment, but this resulted in severe transfer staining. It is had. This is thought to be because the oil-absorbing pigment in the desired copy area, which faces the desensitized printing area, absorbs the desensitizer. - For boat fishing, it is better to use pigments with high oil absorption from the viewpoint of color development, but there are restrictions on the pigments that can be used due to transfer stains caused by desensitizing ink. Conventionally, white pigments used in color developer sheets for pressure-sensitive copying paper manufactured by Manufacturer Bonn include heavy and light calcium carbonate, kaolin, aluminum hydroxide, and the like, with calcium carbonate being the most commonly used. Ordinary calcium carbonate includes light calcium carbonate and heavy calcium carbonate in the form of cubes, columns, spindles, amorphous 9, etc., but in order to improve color development and printability, aragonitic acicular calcium carbonate aggregates are used. The use of is disclosed. However, even with the use of such calcium carbonate, satisfactory results have not yet been obtained.

[Problem to be solved by the invention]

In view of the above, the present invention aims to obtain a color developer sheet for manufacturer-bonded copying paper that has excellent color development properties and is extremely free from transfer stains caused by desensitized ink, while maintaining the excellent characteristics of organic color developers. shall be.

[Means to solve the problem]

In order to solve the above problems, the inventors of the present invention, as a result of intensive studies, found that a color developer sheet for manufacturer-bonded copying paper is provided with a color developer layer containing an electron-accepting organic color developer, an adhesive, and a pigment as main components. As a pigment, the BET specific surface area is 25 to 55rrf
/g, BET specific surface area (m/g)/average particle diameter (μm
) is in the range of 5 to 110, the oil absorption amount by Ogura method is 120 ml / 100 g or more, and the water absorption amount is 1.8
By using calcium carbonate that is more than g/g,
It has been found that this problem can be effectively solved, leading to the present invention. Regarding the calcium carbonate used in the present invention that satisfies the above conditions, the one disclosed in JP-A-1-230424 can be used as is. The above effect can be obtained by using the corresponding calcium carbonate in an amount of 5 to 100% by weight, preferably 10 to 60% by weight, of the pigment solid content of the color developer layer. If it is less than 5% by weight, it will not be effective at all. Since the corresponding calcium carbonate has high water absorption, it is preferable to use it in an amount of 60% by weight or less of the pigment when used as a high solid content coating liquid. Pigments that can be used in combination include those conventionally used in the color developer layer of Manufacturer Bonn pressure-sensitive copying paper, such as heavy calcium carbonate, light calcium carbonate,
Kaolin, calcined kaolin, talc, aluminum hydroxide, aluminum silicate, zinc oxide, activated clay, finely divided silicic acid,
Common white pigments include titanium oxide, calcium silicate, urea-formaldehyde resin, and the like. As the adhesive used in the color developer layer, conventionally known adhesives are used. For example, proteins such as casein and gelatin, cellulose derivatives such as carboxymethyl cellulose and hydroxymethyl cellulose, water-soluble natural polymer compounds such as sucrose such as oxidized starch and esterified starch, as well as polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylic acid, and styrene. butadiene latex,
Water-soluble synthetic polymer compounds and latexes such as acrylonitrile-butadiene-acrylic acid latex and styrene-maleic anhydride copolymer can be used. Examples of the electron-accepting organic color developer used in the color developer layer of the present invention include novolac type phenol resin and its polyvalent metal salt, salicylic acid derivative and its polyvalent metal salt, salicylic acid resin and its polyvalent metal salt, etc. can be mentioned. Novolac type phenolic resins are produced by polycondensing various phenol derivatives and lower aldehydes such as formaldehyde as raw materials in the presence of an acidic catalyst. Examples of phenolic raw materials used at this time include:
Unsubstituted phenol, alkyl group-substituted phenol (e.g., cresol, ethylphenol, butylphenol, octylphenol, nonylphenol, etc., mainly para-substituted products), aralkyl group-substituted phenol (e.g., para-hensylphenol, para-cumylphenol, etc.), aryl group-substituted phenols (e.g., para-phenylphenol)
, or halogen-substituted phenol (eg, para-chlorophenol). Salicylic acid derivatives include compounds having at least one aromatic substituent, specifically 3-phenylsalicylic acid, 5-phenylsalicylic acid, 3-benzylsalicylic acid, 5-benzylsalicylic acid, 3-(α-methylbenzyl)salicylic acid. , 5-(α-methylbenzyl)salicylic acid, 3-(α. α-dimethylhensyl)salicylic acid, 5-(α. α-dimethylhensyl)salicylic acid, 3.5-diphenylsalicylic acid, 3.5-dibedzyl salicylic acid, 3,5-
Di(α-methylbenzyl)salicylic acid, 3,5-di(α
, α-dimethylbenzyl)salicylic acid, 3,5-di(4
-methylbenzyl) salicylic acid and the like. Further, polyvalent metal salt compounds comprising salicylic acids, rosins, and polyvalent metal compounds disclosed in JP-A-2-563 can also be mentioned as preferred color developers. Salicylic acids have a total carbon number of 8 or more, especially 8 to 2.
A known salicylic acid compound having an alkyl group is used. Rosins include gum rosin, wood rosin, tall oil rosin, disproportionated rosin, hydrogenated rosin, polymerized rosin, maleated rosin, fumarized rosin, formaldehyde-modified rosin, rosin phenolic resin, and other natural,
Any modified rosin can be used effectively. The polyvalent metal salt compound is produced, for example, by the following method. Dissolve salicylic acids and/or rosins in a solvent such as ethers, ketones, acetic esters, etc., add a polyvalent metal compound and an inorganic ammonium salt, heat at 40 to 100°C for 1 to 6 hours, and filter the product. It is obtained by performing distillation to remove unreacted inorganic compounds and solvents. As the salicylic acid resin and its polyvalent metal salt, all of the above-mentioned compounds can be used; examples include the above-mentioned salicylic acid derivatives and styrene, 09m. Salicylic acid resin obtained by subjecting styrene derivatives such as p-methylstyrene, α-methylstyrene, and β-methylstyrene to a Friedel-Crach reaction under a co-acid catalyst at a molar ratio of 10.5 to 10 and converted to a polyvalent metal salt. can be mentioned. Types of polyvalent metals include CaXMg and AI. Zn, Mn, etc. may be mentioned, but it is most preferable to use it as a zinc salt. In addition, the ratio of the color developer and pigment used in the color developer layer is 51
The range of 00 to 25:100 is preferable, and the developer coating amount is usually used in the range of 0.05 to 1.5 g/rrf. These pigments and color developer are smeared on a support together with an adhesive, and the support may be paper, synthetic paper, nonwoven fabric, plastic film, or the like. Further, a developer layer may be provided by forming an intermediate coating layer made of pigment, adhesive, etc. on these supports. The method of coating the developer layer and intermediate coating layer is not particularly limited, and may be applied by various coating methods such as an air knife coater, blade coater, roll coater, curtain coater, rot coater, or graphia coater. Can be manufactured by on-machine or off-machine coating. So-called wet-on-wet smearing with two layers simultaneously is also possible. In addition, antifoaming agents, water retention agents, water resistance agents, penetrants, dispersion stabilizers, antioxidants, fluorescent dyes, lubricants, etc. are added to each coating of the developer layer and intermediate coating layer as necessary. can do. Hereinafter, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited to these. In addition, (part) in an Example shows a weight part.

【Example】

(a) Synthesis of salicylic acid resin 3.5-di(4-methylbenzyl)salicylic acid 6, 9
g (0.02 mol), 50 ml of ethyl ether, and 12 g of sulfuric acid as a catalyst were charged into a glass reactor and maintained at a temperature of 20 to 30° C. without stirring. Then, 6.24 g (0.06 mol) of styrene was added dropwise over 8 hours at the same temperature to cause a reaction. After dropping, the solution was aged for 8 hours at the same temperature, then hot water was added and the solvent was distilled off.
The deposited precipitate was filtered. This was vacuum dried to obtain 13.0 g of a white resin. The weight average molecular weight of the obtained resin was 1380, and the softening point was 620°C when measured using a ring and ball softening point measuring device according to JIS-2548. (b) Synthesis of salicylic acid resin polyvalent metal salt 10 g of the resin obtained in (a) and 0.65 g of caustic soda are mixed in 200 ml of hot water.
When it was stirred, it dissolved. Then, the temperature of the solution was increased to 30
Zinc sulfate heptahydrate 2 was prepared in advance while keeping the temperature at ~35°C.
．． A solution of 5 g dissolved in 30 ml of water was added dropwise over 30 minutes. A white precipitate was precipitated, and after continued stirring at the same temperature for 2 hours, it was filtered, washed with water, and dried, resulting in a white powder (10.5%).
g (yield quantitative) was obtained. This is a zinc salt of salicylic acid resin, and the zinc content was analyzed to be 4.82%. (c) Preparation of color developer dispersion The metal salt of the salicylic acid resin obtained in (b) was used as a color developer, and the following composition was dispersed with a sand grinding mill to prepare a suspension. Color developer: 10 parts by weight 10% polyvinyl alcohol aqueous solution (Kuraray #117) 3 parts by weight Water
22.5 parts by weight Next, a color developer dispersion A having the following composition was prepared using the suspension. Also, instead of salicylic acid resin as a color developer, 3.5-
Color developer dispersion B was obtained in the same manner using zinc di-15N-butylsalicylate. Using the various pigments shown in Tables 1 and 2, create a developer coating solution with the following formulation, smear it with a blade coater so that the dry coating amount is 4.5 g/m, and dry it. , Examples and Comparative Examples of color-developing sheets for copying paper manufactured by Bonn were obtained. (Developer coating liquid formulation) Color developer dispersion A or 8 35.5 parts Sodium pyrophosphate 0°5 parts Pigment
100 parts 10% oxidized starch aqueous solution
Table 3 shows the pigment ratio in the 150 parts developer coating solution. Table 1 Table 2 Table 3 The color developing sheets for manufacturer-bonded copying paper obtained in the above Examples and Comparative Examples were evaluated as follows. Desensitizing ink (Fuji Photo Film ■) on the coating surface of the developer sheet
FN-103) with an ink volume of 1゜0.1.5.2
．． Printing was performed using a printing machine so that the density was 0.2.5 g/rrf, and the sheets were folded and stacked so that the desensitized printed portion faced the developer-coated surface that had not been desensitized printed. 100g/
Three days after applying a load of al, the color developer sheet on the desensitized printed side of the printed matter and the color developer sheet opposite to the desensitized printed area were overlapped with a commercially available Mitsubishi NCR Paper Blue, and color was developed by calendaring. (Color density) The reflectance of the area not subjected to desensitization printing was determined by Nihon Heavy Industries (
It was measured with a color difference meter NDIOIDP model manufactured by Co., Ltd., and the reflectance of the colored part / reflectance of the untreated part (background part) x 100 (%)
) comparisons were made based on the values of This value indicates that the smaller the value, the darker the color density. (Desensitization effect) The effectiveness of desensitization was determined based on the whiteness of the desensitized printed area after color development. The evaluation was as follows: ◯: good desensitization effect, △: desensitization was a little difficult but no problem in practical use, ×: desensitization was not effective. (Transfer stains due to desensitizing ink) The degree of transfer stains due to desensitizing ink was determined based on the color density after color development on the side opposite to the desensitized printed portion of the ink amount judged to be sufficiently desensitized. The verdict is ◎
Good with no transfer stains, ○ slight transfer stains, no practical problems, △: slight transfer stains, ×: transfer stains, poor. Table 4 shows the comparison results obtained by the above method. Table 4

【Effect of the invention】

As mentioned above, specific surface area, average particle size, oil absorption, water absorption,
By using calcium carbonate, which is limited by the following, as a pigment component of the color developer layer, it was possible to obtain a color developer sheet for Manufacturer's Bonn copying paper that has excellent color development and is less prone to staining due to transfer of desensitized ink.

Claims (1)

[Scope of Claims] 1. In a color developer sheet for Manufacturer Bonn copying paper provided with a color developer layer containing an electron-accepting color developer, an adhesive, and a pigment as main components, The color developer is an organic color developer, and the BET specific surface area of the pigment is 25 to 55.
m^2/g, the ratio of BET specific surface area (m^2/g)/average particle diameter (μm) is in the range of 5 to 110, the oil absorption amount by Ogura method is 120 ml/100 g or more, and the water absorption amount is 1
．． A color developing sheet for Manufacturer Bonn copying paper, characterized in that it uses calcium carbonate of 8 g/g or more. 2. The color developer sheet for Manufacturer Bonn copying paper according to claim 1, wherein the electron-accepting organic color developer is one or more selected from salicylic acid derivatives and polyvalent metal salts thereof. 3. The electron-accepting organic developer is one or more selected from a resin obtained by reacting a styrene derivative with a salicylic acid derivative having an aromatic substituent, or a polyvalent metal salt thereof. Manufacturer Bonn color developer sheet for copy paper. 4. The color developer sheet for Makerbon copying paper according to claim 1, wherein the electron-accepting organic color developer is a polyvalent metal salt compound consisting of salicylic acids, rosins, and a polyvalent metal compound.