JPS6333477B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a colorless plain paper transfer type pressure-sensitive copying paper that can be copied and recorded on plain paper. The conventionally known form of pressure-sensitive copying paper is to dissolve an electron-donating, colorless coloring agent in a non-volatile oil, etc., create microcapsules with the coloring agent-containing oil as a core material, and then attach the coloring agent to the support. The upper paper coated on the back side and the lower paper coated with an electron-accepting colorless color developer on the surface of the support are placed so that each coating layer faces each other, and the surface of the upper paper is written on, using a typewriter, etc. When printing under pressure, a colored image can be obtained on the bottom paper. When making three or more copies, use inner paper coated with a developer on the surface of the support and microcapsules containing a color former on the back of the support. A large number of copies can be obtained by inserting as many copies as necessary between the upper and lower sheets. There is also a so-called self-coloring type pressure-sensitive copying paper in which microcapsules containing a color former and a color developer are coated on the same side of a support. Since these forms do not use colored substances, they do not stain hands or clothes, and are widely used for office paper and the like. However, when used, at least two, and usually three,
Seed-type coated paper, that is, top paper, middle paper, and bottom paper, must be manufactured, and the reproduced image must be produced using a support coated with a color developer, etc., of middle paper, bottom paper, or self-coloring pressure-sensitive paper. It has the disadvantage that it can only be obtained physically. Furthermore, with the above-mentioned self-coloring pressure-sensitive copying paper, even if the coated layer and plain paper are overlapped and printed, a colored image is obtained only on the coated layer, and the image transferred to the plain paper is not bright enough. It is already known that this is not possible. The term "plain paper" as used herein means a support in which neither an electron-donating color former nor an electron-accepting color developer is present on the transfer surface of the support. Pressure-sensitive copying paper in which a color forming agent and a color developer are present on the same side of a support and which can form a copied image on plain paper are disclosed in Japanese Patent Application Laid-open No. 126111/1983 and Japanese Patent Publication No. 53-1982. Publication No. 16728, Japanese Unexamined Patent Publication No. 159008
There are some that are disclosed in the publication. JP-A No. 54-126111 discloses that a coating solution prepared by adding a solid color former and a color developer to a wax is coated in a single layer on a support, and the coating solution has the following properties:
It has been clearly shown that immediately after mixing a color forming agent and a color developer, a color reaction occurs and the color changes directly. That is, the present invention relates to a pressure-sensitive transfer material having a colored coating layer, such as so-called back carbon paper, and because the coating layer is colored, there is a disadvantage in appearance. Tokuko Showa 53
Publication No. 16728 relates to chelate coloring, in which an encapsulated reactant is coated on a support, and then a co-reactant dissolved in a solvent is coated on top of that, and since a solvent is used, The walls of the microcapsules must be made of a material that is resistant to solvents, which is limiting. There are also many disadvantages in terms of repatriation and economics. JP-A-54-159008 discloses the use of waxes, and after coating color developer oil microcapsules together with a binder on a support, a layer containing waxes and a color developer is further applied thereon. This is a so-called two-layer coating method. In this form, a color developer must be applied after the microcapsule layer is coated on the entire surface using an air knife coater or the like, which increases the number of manufacturing steps and the cost accordingly. In addition, since the microcapsule layer is coated on the support with a binder in the same way as the top paper of commercially available pressure-sensitive copying paper, the layer is hardly transferred to plain paper, and the capsules may be destroyed during printing. A part of the free color former-containing oil moves into the support, and the amount of color former involved in color development is limited, which is disadvantageous in terms of transferability and color development. On the other hand, the present inventors have already filed an application for plain paper transfer type pressure-sensitive copying paper containing a surfactant in the coating layer in Japanese Patent Application No. 106051/1983 dated August 1, 1975. . The plain paper transfer type pressure sensitive copying paper forms a clear image when pressed and printed with the plain paper facing down, and directly contacts the coated surface of the plain paper transfer type pressure sensitive copying paper itself, that is, the plain paper. The effect of the surfactant was able to completely eliminate the coloration on the exposed surface. When a large number of copies are to be made from the plain paper transfer type pressure sensitive copying paper, the plain paper transfer type pressure sensitive copying paper can be treated in the same manner as so-called inner paper for conventional pressure sensitive copying paper. For example, when you stack two sheets of the above-mentioned plain paper transfer type pressure-sensitive copying paper with the coated side facing down, and make three copies with the plain paper layered at the bottom, the middle sheet (second sheet) is the support. The front side is printed in color, and the back side is a coated surface. We conducted research on the long-term stability, especially both heat resistance and moisture resistance, of the above-mentioned plain paper transfer type pressure-sensitive copying paper, which corresponds to this so-called inner paper, and the third sheet of plain paper on which prints were formed. Compared to plain paper, the second sheet of plain paper transfer-type pressure-sensitive copying paper had the disadvantage that the surfactant in the coating layer caused migration, reaching the colored image on the opposite side of the support and desensitizing it. . As a result of intensive research to solve the above-mentioned drawbacks, the present inventors have discovered an electron-donating, colorless coloring agent, an electron-accepting, colorless developer that reacts with the coloring agent to produce a colored product, and waxes. In addition, by adding an adhesive mainly composed of styrene-butadiene copolymer to the coating component consisting of a surfactant and applying it to the surface of the support, it can be transferred to plain paper with excellent stability, transferability, and color development. It was possible to obtain a colorless plain paper transfer type pressure-sensitive copying paper on which an image can be obtained. That is, the present invention basically provides at least two colorless coating layers having a colorless coating layer consisting of the following, and
This is a plain paper transfer type pressure-sensitive copying paper characterized by combining two sheets of coated paper and plain paper. An electron-donating colorless color former and an electron-accepting colorless color developer, both or either of which are dissolved in oil and encapsulated, a surfactant, and waxes containing up to 25% by weight based on the solid content of styrene. - Adhesives based on butadiene copolymers. Further, the present invention will be explained in detail. Both or one of the color former and color developer used in the present invention is microencapsulated. That is, one of them is necessarily in the form of microcapsules, and the color former or color developer is dissolved and contained in a solvent. The color former and the color developer cause a color reaction using a solvent as a medium. When making multiple copies using the plain paper transfer type pressure-sensitive copying paper of the present invention, use the plain paper transfer type pressure-sensitive copying paper of the present invention with the coated side facing down instead of the inner paper for conventional pressure-sensitive copying paper. All you have to do is overlap them. By placing plain paper at the bottom position, it is possible to make multiple copies. Here, the opposite side of the coated surface of the plain paper transfer type pressure-sensitive copying paper of the present invention with the support as a border has the same surface as the plain paper, and a printed image is formed on this surface by applying pressure. If a surfactant is included in the coating layer to prevent coloring of the coated surface after pressure printing, the printed image on one side of the support will be a clear printed image due to the surfactant migrating inside the support. Therefore, we conducted research on various adhesives in order to prevent migration of surfactants by forming a film on the surface of the support at the same time as the original adhesive effect by mixing adhesives, and as a result, color formers , it was found that the inclusion of an adhesive mainly composed of styrene-butadiene copolymer in the coating components consisting of a color developer, waxes, and surfactants is extremely effective for improving image stability, especially heat resistance and moisture resistance. I came to discover it. That is, styrene-
Mixing the butadiene copolymer has the property of not causing a decrease in color density in the heat-and-moisture resistance test. Generally speaking, there are various types of adhesives, both natural and synthetic, but styrene-butadiene copolymer is the main ingredient, and various other adhesives may also be used in combination. For example, natural products include oxidized starch, dextrin, hydroxyethylcellulose, gum arabic, casein, and gelatin. Synthetic products include vinyl acetate, vinyl acetate-acrylic acid copolymer, ethylene-vinyl acetate copolymer, acrylonitrile, acrylonitrile-butadiene copolymer, acryl-
Examples include styrene copolymer, polyacrylamide, methyl methacrylate, polyvinyl alcohol, vinylidene chloride copolymer, carboxymethyl cellulose, and styrene-maleic anhydride copolymer. The styrene-butadiene copolymer of the present invention preferably has a solid content of 5 to 30% by weight in the coating liquid in order to maintain image stability and adhesion of the coating layer. More preferably, it is 10 to 25 percent by weight. If the amount is less than 5% by weight, there will be no effect on image stability, and if it is more than 30% by weight, the color density of the transferred image will be too low, resulting in undesirable results. Further, other adhesives to be used in combination with the styrene-butadiene copolymer may be appropriately added in amounts that do not cause any adverse effects relative to the amount of the styrene-butadiene copolymer. As the surfactant used in the present invention, any of anionic, cationic, nonionic, and amphoteric surfactants are effective. For example, anionic surfactants include fatty acid salts, alkyl sulfate ester salts, alkylbenzene sulfonates,
Examples include alkylnaphthalene sulfonate, alkyl sulfosuccinate, alkyl phosphate ester salt, polyoxyethylene sulfate ester salt, and naphthalene sulfonic acid formalin condensate. Examples of cationic surfactants include alkylamine salts and quaternary ammonium salts. Nonionic surfactants include polyoxyethylene alkyl ether, polyoxyethylene alkyl phenol ether, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, polyoxyethylene alkylamine, polyoxyethylene fatty acid ester, glycerin fatty acid ester,
Examples include oxyethylene and oxypropylene. Examples of the zwitterionic surfactants include alkyl betaines. As the coloring agent used in the present invention, a colorless or light-colored electron-donating organic compound can be used. For example, 3,3-bis(P-dimethylaminophenyl)-6-dimethylaminophthalide, 3,
3-bis(P-dimethylaminophenyl)phthalide, 3-(P-dimethylaminophenyl)-3-
(1,2-dimethylindol-3-yl)phthalide, 3-(P-dimethylaminophenyl)-3-
(2-methylindol-3-yl)phthalide,
3-(P-dimethylaminophenyl)-3-(2-
phenylindol-3-yl)phthalide, 3,
3-bis(9-ethylcarbazol-3-yl)
-Triarylmethane compounds such as 5-dimethylaminophthalide. Dimethylmethane compounds such as 4,4'-bis-dimethylaminobenzhydrin benzyl ether, N-halophenyl-leucoauramine, N-2,4,5-trichlorophenylleucoauramine, rhodamine B-anilinolactam , 3-dimethylamino-7-methoxyfluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-6,8-dimethylfluorane, 3-diethylamino-7-methylaminofluorane, 3.7-diethylaminofluorane ,
Xanthene compounds such as 3-diethylamino-7-dibenzylaminofluorane and 3-diethylamino-chloroethylmethylaminofluorane, thiazine compounds such as benzoylleucomethylene blue and P-nitrobenzylleucomethylene blue, and 3-methyl-spirodi Coloring agents such as spiro compounds such as naphthopyran, 3-ethyl-spirodinaphthopyran, 3,3'-dichlorospirodinaphthopyran, and 3-propyl-spirodibenzopyran can be used alone or in combination. As a color developer, inorganic acid substances such as acid clay, activated clay, kaolin, zeolite, bentonite, attapulgide, substituted phenols, phenol-formalin condensates, alkyl-substituted phenol-formalin condensates, aryl-substituted phenol-formalin condensates, etc. Phenolic color developer and its metal salts, benzoic acid, chlorobenzoic acid, toluic acid, salicylic acid, 5-tert-butylsalicylic acid, 3,5
-di-tert-butylsalicylic acid, 3,5-di(α
Salicylic acid color developers such as -methylbenzyl)salicylic acid and their metal salts are known, and these can be used alone or in combination. When using a color developer in microcapsule form, an oil-soluble color developer such as a phenolic or salicylic acid developer is preferred. These color formers and/or color developers are microencapsulated by methods known in the art.
Namely, there are monomer polymerization methods, phase separation methods, spray drying methods, etc. Film-forming wall materials include gelatin, casein, gum arabic, rosin, starch, collagen, sodium alginate, ethyl cellulose, carboxymethyl cellulose, benzyl cellulose, Polyvinyl alcohol, polyethylene, polyamide, polyester polyurethane, polyacrylamide, polyethyleneimine, etc. are used, but are not particularly limited. Nonvolatile oils used for microencapsulation include alkylnaphthalene-based, chlorinated paraffin-based, diarylethane-based, alkyldiphenyl-based, aromatic ester-based, and fatty acid ester-based oils, which can be used alone or in combination. do. Waxes include animal-based waxes such as beeswax, spermaceti wax, Chinese wax, and lanolin, plant-based waxes such as Candelilla wax and carnauba wax, and mineral waxes such as montan wax, ozokerite, ceresin, and lignite wax. Petroleum-based waxes such as waxes, paraffin waxes, and microcrystalline waxes; modified waxes such as montan wax derivatives, paraffin wax derivatives, and microcrystalline wax derivatives; hydrogenated waxes such as Castor waxes and opal waxes; Low molecular weight polyethylene and its derivatives, synthetic waxes such as acra wax and distearyl ketone, cabroic acid amide, caprylic acid amide,
Saturated fatty acid amides such as pelargonic acid amide, capric acid amide, lauric acid amide, tridecylic acid amide, myristic acid amide, stearic acid amide, behenic acid amide, ethylene bisstearic acid amide, caproleic acid amide, myristoleic acid amide, olein Amide waxes such as unsaturated fatty acid amides such as acid amide, elaidic acid amide, linoleic acid amide, erucic acid amide, ricinoleic acid amide, and linoleic acid amide can be used alone or in combination. In the present invention, 25% by weight or less based on the solid content of the electron-donating colorless color forming agent, the electron-accepting colorless color developer, and the surfactant, both or either of which are dissolved in oil and encapsulated. Waxes are preferred. The method for producing the plain paper transfer type pressure-sensitive copying paper according to the present invention includes applying an aqueous dispersion coating solution to the entire surface or one part of the support using a general coater such as an air knife coater or a printing machine such as a flexo printing machine. You can choose how you want to apply it to the area. When preparing the coating liquid according to the present invention, a liquid property improver can be added depending on various coaters and printing machines. Examples include thickeners that keep the viscosity constant and surfactants that improve dispersibility, but it is clear that they are not limited to these. As the support for forming the coating layer according to the present invention, paper is mainly used, but various nonwoven fabrics, plastic films, synthetic papers, metal foils, etc., or composite sheets made of a combination of these may also be used. Hereinafter, the present invention will be specifically explained with reference to Examples. Note that "parts" indicate parts by weight. Example 1 (1) A microcapsule dispersion containing a coloring agent was prepared as follows. 80 parts of a 1,1-diphenylethane solution containing 4.8 parts of crystal violet lactone (CVL) dissolved in 100 parts of a 5% aqueous solution at pH 4.0 in which a styrene maleic anhydride copolymer was dissolved together with a small amount of sodium acetate was added. Emulsified. melamine 10
1 part, 25 parts of a 37% formaldehyde aqueous solution, and 65 parts of water were adjusted to pH 9 with sodium hydroxide and heated to 60°C. The mixture became transparent in 15 minutes, and a melamine-formalin initial condensate was obtained. This initial condensate was added to the emulsion, the temperature of the liquid was raised to 60°C, and stirring was continued. Formation of capsules was confirmed in 30 minutes, so the emulsion was cooled to room temperature. The solid content of the obtained microcapsule dispersion was about 45%. (2) A microcapsule dispersion containing a color developer was prepared as follows. In place of 4.8 parts of CLJ in (1) above, use 32 parts of P-phenyl-phenol resin, and
A developer capsule containing a phenolic resin was obtained. The solid content of the obtained microcapsule dispersion was about 45%. (3) Using the microcapsule dispersion prepared in (1) and (2) above, 45% paraffin wax dispersion, nonionic surfactant primary linear alcohol ethoxylate (trade name Adecatol LO-
15, manufactured by Asahi Denka Kogyo) and styrene-butadiene latex (product name Nipol LX204, manufactured by Nippon Zeon) was prepared with the following formulation, and applied to a base paper with a basis weight of 48 g/m ² at 9 g/m ² It was applied with a Mayer bar so that 45% color former capsule dispersion 10 parts 45% color developer capsule 〃 50 parts 45% paraffin wax emulsion 15 parts Nonionic surfactant 3 parts 40% styrene-butadiene latex 23 parts Water 150 parts Obtained here Two sheets of plain paper transfer-type pressure-sensitive copying paper with anhydrous coating layers were stacked with high-quality paper with each coating layer facing down, and printed using a typewriter. A clear blue transfer image was obtained on high-quality paper. On the other hand, no self-coloring occurred on the coated surface, and the coated layer remained colorless as the background surface. After pressing the type, the second and third sheets were subjected to a heat and humidity test at a humidity of 90% and a temperature of 45°C for one day and night, and compared with the color density of the untested ones, the decrease in color density due to the heat and humidity test was determined according to the formula below. When the degree of deterioration (%) was determined, the degree of deterioration of the second and third copies was 3% and 1%, respectively. Degree of decrease (%) = Untested color density - Color density after test /
Untested color density x 100 Examples 2 to 13 and Comparative Examples 1 to 13 Plain paper transfer type pressure-sensitive copying paper was prepared in the same manner as in Example 1, except that the type and amount of adhesive shown in Table 1 below was used. Obtained.

【table】

【table】

[Table] As shown above, when comparing the Examples and Comparative Examples, it can be seen that the degree of decrease is clearly lower in the Examples.

Claims (1)

[Scope of Claims] 1. Plain paper transfer type pressure-sensitive copying characterized by combining plain paper and at least two sheets of coated paper each having a colorless coating layer on a support that basically consists of the following: paper. an electron-donating colorless color former and an electron-accepting colorless developer, both or either of which are dissolved in oil and encapsulated; a surfactant; Adhesive based on styrene-butadiene copolymer.