JPH0485076A - Carbonless pressure-sensitive copy paper - Google Patents

Abstract

PURPOSE:To reduce developed color contamination to a large extent in such a case that sufficiently developed density is obtained by using an associable high-molecular compound in a coating solution containing a microcapsule including a color former, a buffer material and a binder based on latex. CONSTITUTION:A coating solution containing a microcapsule including a color former, a buffer material and a binder is applied to paper and dried to obtain carbonless pressure-sensitive copy paper. At this time, as the binder, various latexes such as styrene/butadiene copolymer latex, vinyl acetate type latex or acrylic type latex or alkali thickening latexes thereof are used. As the associable high-molecular compound in the coating solution, a water-soluble high- molecular polymer having hydrophobic groups locally formed at least at two places thereof or hydrophobic groups locally formed at least to both terminals or an emulsion thereof is pref.

Description

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

The present invention relates to carbonless pressure sensitive copying paper having a coating of microcapsules. More specifically, the present invention relates to a carbonless pressure-sensitive copying paper that has excellent stain resistance and coating suitability.

[Conventional technology]

Carbonless pressure-sensitive copying paper is usually produced by coating a support with microcapsules containing a colorless leuco dye (coloring agent) and a color developer. Each is coated individually on a support and used as a top paper and a bottom paper, and each coated on both sides is generally used as an inner paper. Self-contained papers have also been used in which one or two layers of each are coated on one side of the support. Multiple sheets of these sheets are combined as appropriate, and physical pressure is applied by writing, typewriter, impact printer, etc. to destroy the microcapsules, and the leuco dye inside the capsules comes into contact with the color developer, causing color development. This is a system that can obtain recorded images. In general, the following two items are listed as important quality conditions required for carbonless pressure-sensitive copying paper. 1. Dark and clear images can be obtained in a short time and there is no deterioration over time. 2. When color development is not intended, i.e., during the manufacturing process of carbonless pressure-sensitive copying paper, during cutting and various printing processes, and during storage and handling in sheet or rolled form, color development stains should not occur. Above 1. and 2. Since these are contradictory effects, it is generally difficult to fully satisfy both and maintain a balance. In general, a coating layer containing microcapsules consists of microcapsules, a buffer material, a binder, and other additives, but these include: ■ Manufacturing conditions for microcapsules, ■ Type and amount of buffer material, ■ Type and amount of binder, Partial improvements can be made by modifying factors such as, and many proposals have been made regarding this. ■The method for producing microcapsules containing a coloring agent is as follows:
Although many are known, the representative methods include: - Coacervation method using a polyion complex of gelatin-gum arabic.・An interfacial polymerization method that forms an insoluble film at the interface between a hydrophilic liquid as a dispersion medium and a hydrophobic liquid to be included.・After adding a coating resin initial condensate such as melamine-formalin resin or urea-formalin resin from the hydrophilic liquid side that will serve as a dispersion medium, it is converted into a resin and encapsulated in 5 steps.
itu polymerization method. can be mentioned. Recently, raw materials are cheap and stably supplied, highly concentrated microcapsule emulsions can be obtained, and the manufacturing process is simple.
For these reasons, synthetic resin capsules, especially capsules produced by in-5-itu polymerization, have come to be used. Regarding the type of binder (2), proposals have recently been made to use various latexes. The latex itself can be combined with other known binders (polyvinyl alcohol, starch glue, etc.)
It has the advantage of higher cushioning properties. However, since it is a fine emulsion, its permeability into the support layer is high and sufficient effects cannot be obtained in many cases. As a solution to this problem, it has been proposed to use all or part of an alkali-thickened latex with reduced permeability (Japanese Patent Laid-Open Nos. 64-49678, 1-234289,
JP-A-1-234290, JP-A-1-288480, JP-A-2-3367, and other publications). Although a number of proposals have been made as described above, the current situation is that nothing satisfactory has been obtained yet.

[Problems to be solved by the invention]

The present invention simultaneously overcomes the quality and manufacturing problems of conventional carbonless pressure sensitive copying paper. That is, the purpose is to significantly reduce color stains when sufficient color density is obtained. Specifically, the balance characteristics of the following ^ and B, which are contradictory factors, are improved. Improved A0 color development. A dark and clear copy image can be obtained, and a clear image can be obtained even when copying a large number of sheets. Prevents coloring stains when B0 coloring is not intended. The types of colored stains are: ・Dynamic colored stains that occur during rubbing; ・Static pressure colored stains that are applied during storage, transportation, printing, and guillotine cutting in rolled or sheet form; ・Heated and humidified conditions. Examples include colored stains caused by capsule destruction during long-term storage. In any of these cases, it should exhibit excellent resistance to color development and staining. The object of the present invention is to obtain carbonless pressure-sensitive copying paper that satisfies all of the above items.

[Means to solve the problem]

As a result of extensive studies, the inventors of the present invention have basically discovered that carbonless pressure-sensitive copying is produced by applying and drying a coating liquid containing microcapsules containing a coloring agent, a buffer material, and a binder whose main component is latex. For paper, the problem could be solved by using an associative polymer compound in the coating liquid. The associative polymer compound used in the present invention has a pH of -7 to 1.
In the region 4, it has the property of associating with latex, microcapsules, etc. and causing them to partially aggregate or aggregate.
It is a water-soluble polymer or a polymer emulsion. In terms of surface chemistry, it is a high-molecular polymer or a high-molecular emulsion that associates with latex, microcapsules, etc. through hydrophobic group interaction. Associative polymer compounds include: 1. A water-soluble polymer or polymer emulsion formed by localizing hydrophobic groups at at least two force points in the polymer. 2. A water-soluble polymer or polymer emulsion in which hydrophobic groups are localized at least at both ends of the polymer. is preferred. Monomers used in polymerization include (olefin derivatives (ethylene, 1-butene, 2-butene, isobutyne,
3-methyl-1-butene, etc.), diene derivatives (propadiene, 1,2-butadiene, 1,3-butadiene, 2.
3-dimethyl-13-butadiene, 1,2-pentadiene, 3-methyl-1,3-pentadiene, 4-methyl-1
3-pentadiene, 1,4-pentadiene, 2-methyl-
1,4-pentadiene, 1,2-hexadiene, 1,3
-hexadiene, 1,4-hexadiene, 1,5-hexadiene, 25-dimethyl-1,5-hexadiene, 3
, 3-dimethyl 1,5-hexadiene, 2-methyl-1
, 5-hexadiene, 3-methyl-1,5-hexadiene, 2.4-hexadiene, 25-dimethyl-2,4-hexadiene, 5.5-dimethyl-24-hexadiene,
Octadiene, nonadiene, 1,9-decadiene, 1.
10-undecadiene, etc.), styrene derivatives (styrene, 0-methylstyrene, m-methylstyrene, p-methylstyrene, dimethylstyrene, trimethylstyrene, isopropylstyrene, methoxystyrene, nitrostyrene, aminostyrene, p-vinylbenzenesulfone Acid, Na p-vinylbenzenesulfonic acid. p-vinylbenzenesulfonic acid with 1α-methylstyrene, α-ethylstyrene, etc.), vinyl ester derivatives (vinyl acetate, vinyl butyrate, vinyl pivalate, vinyl caprylate, vinyl laurate) , vinyl palmitate, vinyl stearate, vinyl methacrylate, vinyl crotonate, vinyl cinnamate, vinyl benzoate, vinyl nitrobenzoate, vinyl formate, etc.), vinyl ether derivatives (methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, Isopropyl vinyl ether, n-
Butyl vinyl ether, isobutyl vinyl ether, 1
erf-butyl vinyl ether, 2-ethylhexyl vinyl ether, n-octadecyl vinyl ether, vinyl vinyl ether, allyl vinyl ether, benzyl vinyl ether, phenyl vinyl ether, 2-methoxyethyl vinyl ether, diethylene glycol divinyl ether, etc.), acrylic acid derivatives (acrylic acid, acrylic anhydride, acrolein) , crotonic acid, isocrotonic acid,
andieric acid, tiglic acid, dimethylacrylic acid, methylethylacrylic acid, α[N-acrylocoaminoacrylic acid, α-acetoxyacrylic acid, α-trimethylsilylacrylic acid, Na acrylate, etc.), methacrylic acid derivatives (methacrylic acid, methacrylic anhydride, methacrolein, sodium methacrylate, etc.), acrylic acid ester derivatives (methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 10-undecyl acrylate, 2-ethyl butyl acrylate, vinyl acrylate, 2-ethylhexyl acrylate, 2-
ethoxyethyl acrylate, octadecyl acrylate, cyclohexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, phenyl acrylate, etc.), methacrylic acid ester derivatives (methyl methacrylate, ethyl methacrylate,
Propyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, 2-cyanoethyl methacrylate, isobutyl methacrylate, tridecyl methacrylate, vinyl methacrylate, etc.), acrylamide derivatives (acrylamide, N-methylacrylamide, N-+eu-butylacrylamide, N -benzylacrylamide, etc.), methacrylamide derivatives (
Methacrylamide, N-methylmethacrylamide, N-
terl-butyl methacrylamide, N-benzyl methacrylamide, etc.), acrylonitrile derivatives (acrylonitrile, 2-ethyl acrylonitrile, 2-phenylacrylonitrile, etc.), methacrylamide derivatives, maleic acid derivatives (maleic anhydride, methyl maleic anhydride, dimethyl anhydride, maleic acid, phenyl maleic anhydride,
maleic acid, methylmaleic acid, dimethylmaleic acid,
phenylmaleic acid, etc.), maleic acid ester derivatives (
monomethyl maleate, dimethyl maleate, monoethyl maleate, diethyl maleate, monobutyl maleate, dibutyl maleate, etc.), maleamide derivatives (maleamic acid, maleic diamide, etc.), maleimide derivatives (maleimide, N-methylmaleimide, N- ethylmaleimide, etc.), dicarboxylic acid derivatives (oxalic acid, malonic acid, succinic acid, tartaric acid, itaconic acid, acetylene dicarboxylic acid, glutaric acid, 3-methylglutaric acid, etc.), dicarboxylic acid ester derivatives (monoethyl oxalate, monooxalate, etc.) Phenyl, monoethyl malonate, monophenyl malonate, monoethyl succinate, monophenyl succinate,
Monoethyl tartrate, monoethyl itaconate, monoethyl fumarate, monoethyl acetylene monocarboxylate, monoethyl glutarate, diethyl oxalate, diphenyl oxalate, diethyl malonate, diphenyl malonate, diethyl succinate, diphenyl succinate, diethyl tartrate, itaconic acid Among these, particularly highly hydrophobic monomers include styrene derivatives (styrene, 0-methylstyrene, m-methylstyrene, p-methylstyrene), diethyl fumarate, diethyl acetylenedicarboxylate, diethyl glutarate, etc. , dimethylstyrene, trimethylstyrene, isopropylstyrene, methoxystyrene, nitrostyrene, aminostyrene, α-methylstyrene, α-ethylstyrene, etc.), vinyl ether derivatives (allyl vinyl ether, benzyl vinyl ether, phenyl vinyl ether, etc.), acrylic ester derivatives ( (phenylacrylate, etc.), methacrylic acid ester derivatives, dicarboxylic acid ester derivatives (monophenyl oxalate, monophenyl malonate, monophenyl succinate,
diphenyl oxalate, diphenyl malonate, diphenyl succinate, etc.). The above examples are just a few, and include monomers described in detail in "Polymer Data Handbook, Basic Edition" (edited by the Society of Polymer Science and Technology, Baifukan Publishing, 1986). In addition to this, there are also
No. 90251, No. 55-108411, No. 5
No. 6-47477, No. 58-189299,
In addition to the hydrophilic monomers and hydrophobic monomers described in JP 59-73540, JP 59-89313, JP 59-108075, and JP 61228081, ethylene oxide, propylene oxide, and butylene oxide. , styrene oxide, epichlorohydrin, long chain α-olefin oxide, etc.
This is not the case as long as it is a high molecular weight polymer or high molecular emulsion that associates with latex, microcapsules, etc. through hydrophobic group interaction in a region where tL<) and pH = 7 to 14. Furthermore, the above-mentioned associative polymer compound can be imparted with alkaline thickening properties by containing monomers used in known water-soluble thickeners such as acrylic acid, methacrylic acid, and itaconic acid as its monomer units. I can do it. Alkaline thickening means that as the viscosity of the coating liquid shifts from acidic to alkaline (pH = 7 to 14),
This is a behavior in which type B viscosity increases. The amount of the associative polymer compound to be used varies depending on its associative force, but is preferably in the range of 0.1 to 20 parts based on 100 parts of the solid weight of the microcapsule. Furthermore, 0.1 part ~
A range of 10 parts is particularly preferred. When the above-mentioned associative polymer compound is used in an alkali-thickened form, 0.1 to 5 parts
A range of 50% is preferred. Additionally, it can be applied using less binder than conventional methods. The type B viscosity of the coating liquid is preferably adjusted to, for example, 1 to 1000 cps when the solid content concentration is 20% (liquid temperature = 20°C). Note that this is an example of measurement conditions, and the effects of the present invention are not limited to this coating liquid concentration and coating liquid temperature. If the viscosity is below this range, it is difficult to obtain the effects of the present invention, and if it is above this range, the coating suitability is poor. As the binder, styrene-butadiene copolymer latex, vinyl acetate type, acrylic type various latexes, and alkali thickening latexes thereof are preferable. As the alkaline thickening latex, the commonly used ones mentioned above can be used. There is no problem in using an appropriate amount of a water-soluble polymer substance such as soluble starch, casein, gelatin, gum arabic, polyvinyl alcohol, methylcellulose, or CMC. Usually, the combined amount of these binders is preferably in the range of 0 to 100 parts per 100 parts by solid weight of the microcapsules. Particularly preferred is a range of 0 to 50 parts. The encapsulation method used in the present invention is not particularly limited, but since microcapsules formed by coacervation may have a film destroyed in latex, interfacial polymerization or in-5-in-titu polymerization may be used. It is preferable to use legal encapsulation methods. The emulsifier used for encapsulation is preferably a polymer electrolyte. Specifically, styrene-maleic anhydride copolymer, styrene-benzyl methacrylate-maleic anhydride copolymer, α-alkylstyrene-maleic anhydride copolymer, and nuclear monoalkyl-substituted styrene-maleic anhydride copolymer. Nuclear dialkyl substituted styrene-maleic anhydride copolymer,
Styrene-maleic anhydride monoalkyl ester copolymer, ethylene-maleic anhydride copolymer, polystyrene sulfonic acid, polyacrylic acid. An aqueous solution of acrylic acid-acrylic ester copolymer 9 or the like is used. The emulsifier used for interfacial polymerization encapsulation is
In addition to the above in 5 itu encapsulation, PVA, CM
Aqueous solutions of C, HEC, various (wheat, potato, corn, etc.) starches are also used. It should be noted that there is no problem even if known substances having nonionic, cationic, or amphoteric surfactants are added and used in combination to the extent that they do not cause problems in the encapsulation process. The buffering material is added for the purpose of preventing destruction of the microcapsules. In general, wheat starch, potato starch, corn starch, fine cellulose powder, synthetic plastic pigments, etc. are preferred, and it is usually preferred to use them in an amount of 10 to 400 parts per 100 parts by solid weight of microcapsules. . Furthermore, the range of 10 to 100 parts is particularly preferable. The coating method used in the present invention is a conventional coating machine (
coater) and dried. As a specific coating machine, an air knife coater, a plate coater, a rod coater, a bar coater, a roll coater, a size press coater, a curtain coater, etc. are used. As the support, acidic paper or neutral paper mainly composed of cellulose fibers is usually used, but synthetic paper may also be used. As the color developer used in combination with the carbonless pressure-sensitive copying paper obtained according to the present invention, phenolic resin compounds, salicylic acid metal salt compounds, solid acid compounds, etc. are preferable.

【Example】

Next, comparative examples and examples will be shown. The following parts numbers are expressed in parts by weight of dry solids, unless otherwise specified. Example 1 [Microencapsulation] 4 parts of crystal violet lactone (CVL) was dissolved in a diarylethane solvent (Hysol SAS N-29).
6: manufactured by Nippon Petrochemical Co., Ltd.)) was dissolved in 96 parts. 220 parts of the above hydrophobic liquid was gradually added to 180 parts of a 5% styrene-maleic anhydride copolymer aqueous solution (manufactured by Arayo Kagaku Co., Ltd.) under strong stirring, and the stirring was continued until the volume average particle diameter became 5 microns. Next, an emulsion was obtained. Separately, 11 parts of melamine, 2 parts of 37% formaldehyde aqueous solution
Melamine obtained by heating and dissolving 1.2 parts and 28.2 parts of water.
A formaldehyde initial condensate aqueous solution was added to the emulsion and stirred for 2 hours at a temperature of 70°C to obtain a microcapsule liquid. [Preparation of carbonless pressure-sensitive copying paper (CB)] 100 parts of the above microcapsules, 35 parts of wheat starch, and alkali non-thickening type styrene-butadiene copolymer latex (#
0853: manufactured by Japan Synthetic Rubber Co., Ltd.) and 19 parts of acrylic acid.
One part of an acrylic acid ester copolymer-based alkali-thickened associative polymer emulsion (TT-615: manufactured by Rohm and Haas) was added. The pH was adjusted to 9.0 to obtain a coating liquid for carbonless copying paper. The coating liquid was applied using the air knife coating method to give 40 g/
rr! The dry capsule coating amount is 2°5g/r on high-quality paper.
ri to obtain carbonless pressure-sensitive recording paper (CB). [Measurement of color density and static pressure color stain] The obtained CB was combined with a commercially available carbonless pressure-sensitive copying paper bottom paper (Mitsubishi NCR Paper Shimokawa Shimo Paper 40.40 g/i base bottom paper), and the following was done. Color density and static pressure color stain were measured.・Coloring density The combined upper paper and lower paper were colored under a pressure of 400 kg/cnf. CF receipt reflectance measurement using Nihon Heavy Industries' color difference meter NDIOID
It was measured using P type. The display is expressed as reflectance of colored area/reflectance of untreated area (background area) x100 (%). As this value becomes smaller, the color density becomes deeper. - Static pressure colored stains After holding the combined soil paper and lower paper under a pressure of 20 kg/al for 60 seconds, the stains on the lower paper were measured in the same manner as the color density described above. As this value increases, the amount of static pressure colored stains decreases. Example 2 Replaced 19 parts of #0853 with 5 parts of 9° of #0853,
The same procedure as in Example 1 was carried out except that 9.5 parts of alkali-thickened styrene-butadiene copolymer latex (10628: manufactured by Nihon Gosei Rubber Co., Ltd.) was used. Example 3 The same procedure as in Example 1 was carried out except that 19 parts of #0853 were replaced and 19 parts of 10628 were used. Example 4 The same procedure as in Example 1 was carried out, except that #0853 was replaced with 19 parts and #0853 was used in an arbitrary amount in the range of 5 to 55 parts. Comparative Example 1 #0853 was replaced with 19 parts and TT-615 was replaced with 1 part, #
The same procedure as in Example 1 was carried out except that 20 parts of 0853 was used. Comparative Example 2 #0853 was replaced with 19 parts and TT-615 was replaced with 1 part, #
The same procedure as in Example 1 was conducted except that 19 parts of 0853 and 1 part of alkali thickened polymer emulsion (ASE-75, manufactured by Rohm & Haas) were used. Comparative Example 3 #0853 was replaced with 19 parts and TT-615 was replaced with 1 part, #
The same procedure as in Example 1 was conducted except that 19 parts of 0628 and 1 part of ASE-75 were used. Comparative Example 4 108.53 was replaced with 19 parts and TT-615 was replaced with 1 part,
The same procedure as in Example 1 was carried out except that 20 parts of #0628 was used. Comparative Example 5 #0853 was replaced with 19 parts and TT-615 was replaced with 1 part, A
The same procedure as in Example 1 was carried out, except that SE-75 was not used or fixed at 1 part, and -#0853 was used in an arbitrary amount in the range of 5 to 60 parts. The results of Examples 1 to 3 and Comparative Examples 1 to 4 are shown in Table 1. The results of Example 4 and Comparative Example 5 are shown in Table 2. (Left below) Table A: Non-alkali-thickened latex B: Alkali-thickened latex C: Alkali-thickened polymer emulsion D = Alkali-thickened associative polymer emulsion

【Effect of the invention】

As is clear from the present invention, a carbonless pressure-sensitive copying paper with a well-balanced color density and static color stain was obtained. Furthermore, unintended effects include the ability to obtain a coating liquid with excellent coating suitability and the ability to reduce the amount of binder used. A: Alkaline non-thickening latex

Claims (1)

[Scope of Claims] 1. In carbonless pressure-sensitive copying paper, which is basically formed by applying and drying a coating liquid containing microcapsules containing a coloring agent, a buffer material, and a binder, the main component of the binder is 1. A carbonless pressure-sensitive copying paper characterized by being latex and using an associative polymer compound. 2. The carbonless pressure-sensitive copying paper according to claim 1, wherein the associative polymer compound is a water-soluble polymer or polymer emulsion having hydrophobic groups localized at at least two locations in the polymer. 3. The carbonless pressure-sensitive copying paper according to claim 1, wherein the associative polymer compound is a water-soluble polymer or polymer emulsion having hydrophobic groups localized at at least both ends of the polymer. 4. The carbonless pressure-sensitive copying paper according to claim 1, 2 or 3, wherein the associative polymer compound is an alkali thickening type.