JPH1178228A - Pressure-sensitive copy paper and set therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide pressure-sensitive copy paper excellent not only in printability inclusive of ink jet printing but also in natural paste aptitude. SOLUTION: In pressure-sensitive copy paper utilizing color forming reaction of an electron donating org. color former and an electron acceptive coupler and used by combining many papers, that is, upper and lower papers or upper paper, at least one middle paper and lower paper, the upper paper having a pigment coating layer containing pigment and an anionic water-soluble polymer and having a contact angle of 15 deg.-60 deg. with respect to water provided on the surface thereof and the lower paper of which the rear surface has a contact angle of 70 deg. or more with respect to water are combined to be used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-sensitive copying paper, and more particularly, to a pressure-sensitive copying paper and a pressure-sensitive copying paper set which are excellent in printability including ink jet printing and also excellent in adhesive property. Things.

[0002]

2. Description of the Related Art A pressure-sensitive copying paper is prepared by applying a microcapsule composition mainly composed of a microcapsule containing a hydrophobic core substance in which an electron-donating color former (leuco dye) is dissolved to one side of a support. On a paper, one side of the support was coated with a color developer component mainly composed of an electron-accepting color developer that developed a color when contacted with the above color former, and the microcapsule composition was coated on the other side. There are paper and lower paper with a developer composition coated on one side of the support, and these three types of sheets are practically used as a copy set by combining upper paper, lower paper or upper paper, middle paper, and lower paper in this order. Has been Self-contained pressure-sensitive copying paper (self-contained paper), in which a color former and a developer are coated on the same surface of the support to enable pressure-sensitive recording with one sheet, is also well known as a form of pressure-sensitive copying paper. Have been.

[0003] The pressure-sensitive copying paper is mainly used as a slip (form) sheet, and the format of the slip is often printed by a printing professional by letterpress printing or offset printing. In recent years, however, there has been a tendency to form in-house by form printing incorporating a non-impact printer when producing small-volume (often many types) slips and self-consumption slips. Known non-impact printers for this purpose include a toner image transfer type electrophotographic copying machine on plain paper, an electrophotographic recording type using a light beam such as a laser, and an ink jet printer. Among them, the ink jet recording method has features such as high-speed printing, low noise, versatility of recording patterns, and easy multicolor printing, and is used in a wide range of fields including information equipment. In particular, images formed by the multicolor ink jet method are comparable to those obtained by the multicolor printing by the normal plate making method, and do not require plate making. Attempts have been made to apply the inkjet method to the field of multicolor printing in addition to mere recording use because of its low cost. Recently, with the streamlining of paperwork, the demand for computer output for numbering of slips and printing of individual information has been increasing.Form printing machines have been equipped with high-speed inkjet recording heads. Use cases in which printing is performed by an ink jet unit as well as a printing unit are increasing.

[0004] Pressure-sensitive copying paper utilizing less as noncontinuous, upper sheet and a lower sheet or upper sheet, cell combining at least one sheet in a, and a large number consisting of lower paper <br/> Tsu In general, it is used by gluing for each set. At this time, a method of stacking each set in multiple stages and applying a specific adhesive composition (tendashi) to one side surface (Japanese Patent Publication No. 44-19036, etc.) is common, and the adhesive force between each set is required. Along with
Adhesion between the sets is unnecessary, and so-called grouping suitability that can be separated by a simple operation is required.

An attempt to provide a pigment coating layer on the surface of the upper paper for pressure-sensitive copying paper has been proposed to provide a pigment coating layer in order to improve the printability of the color developing ink (Japanese Utility Model Application Laid-Open No. 54-179202).
No.), and a proposal to provide a pigment coating layer for the purpose of improving the suitability for multicolor printing and barcode printing (Japanese Utility Model Application Laid-Open No. 1-1693).
No. 63, JP-A-2-134283, JP-A-6-105
No. 9) has been reported. In addition, when a pigment coating layer is provided on the upper paper surface, a coating layer is not usually provided on the upper paper surface and the lower paper back surface. When the layer is provided, the top paste easily permeates, and the upper sheet and the lower sheet which should not be adhered adhere to each other, and it is difficult to separate them. That is, since it is difficult to separate the upper paper, the middle paper, and the lower paper into one set, it is proposed to intentionally increase the surface tension by adding a hydrophobizing agent or a water-repellent agent to the coated surface. JP-A-4-290785
No., JP-A-6-255237, JP-T-Hei 1-50089
No. 5, Japanese Translation of International Patent Application No. 4-506194).

[0006]

However, when a hydrophobic agent or a water repellent is added to the pigment coating layer on the upper paper surface,
In addition to a decrease in the adjustment range of the dampening solution during offset printing, there was a problem in printability such that ink jet printing was too thin and sufficient visual density could not be obtained. It is an object of the present invention to provide a pressure-sensitive copying paper which is excellent in printability including ink jet printing and also excellent in suitability for top paste.

[0007]

According to the present invention, there is provided at least one of an upper sheet and a lower sheet, or an upper sheet, which utilizes a color-forming reaction between an electron-donating organic color former and an electron-accepting developer. Paper and a pressure-sensitive copying paper used in combination of a large number of lower papers, containing a pigment and a cationic water-soluble polymer, and having a contact angle to water of 15 ° to 60 °.
And a lower paper having a contact angle of 70 ° or more with water on the back surface of the paper. In the present invention, an upper sheet and a lower sheet, or an upper sheet, at least one middle sheet, and a large number of sets of lower sheets are stacked, and the viscosity is 3 to 20 cps, the surface tension is 30 to 50 dyne / cm, and the solid content concentration is 8 By gluing one side wall with an adhesive composition of about 30%, a pressure-sensitive copying paper set which can be easily grouped for each required form can be obtained.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
Examples of the white pigment used in the present invention include calcium carbonate, magnesium carbonate, zinc oxide, magnesium oxide, titanium dioxide, aluminum hydroxide, zinc hydroxide,
Kaolin, talc, clay, calcined kaolin, delaminated kaolin, structured kaolin, zeolite, magnesium silicate, aluminum silicate, calcium silicate, magnesium sulfate, calcium sulfate, barium sulfate, calcium phosphate, silica, amorphous silica, colloidal silica, At least one of materials known in the art, such as inorganic pigments such as fine shirasu, activated clay having substantially no color developing ability, and organic pigments (plastic pigment) such as polystyrene resin fine particles, urea formalin resin fine particles, and fine hollow particles. One type is appropriately selected and used. Among them, calcium carbonate is preferably used in an amount of 50% by weight or more based on all pigments because it is particularly excellent in color developability, ink absorbency, and ink drying property.

[0009] Various latexes are generally used to adhere the pigments. As the latex, styrene-butadiene copolymer latex, acrylonitrile-
It can be appropriately selected from latexes known in the art, such as a butadiene copolymer latex, a vinyl acetate latex, and an acrylate latex, and can be used alone or in combination. Methods for producing these latexes include a method based on so-called emulsion polymerization and a method involving emulsifying and dispersing a solution of a polymer substance. For example, Muroi, “Chemistry of Polymer Latex” (published by Kobunshi Kanbunkai), Kamihara et al. Rubber Handbook "(published by Asakura Shoten) describes the manufacturing method in detail. Many latexes suitable for use in the technical field are also commercially available, and are appropriately selected and used.

In the present invention, a commercially available cationic resin is preferably used as the cationic water-soluble polymer contained in the pigment layer. For example, a condensate of an amine and epichlorohydrin, an initial condensate of an amine and formalin, a polyamine-based cationic resin such as a polyamine, a dicyandiamide low-polymer and a polyamine compound (amine is preferably a lower amine), an ammonium dicyandiamide chloride and a dicyandiamide formalin condensate Such as dicyandiamide-based cationic resin, cationic polyacrylamide resin,
Examples include polyamide polyamine epichlorohydrin resin, cationic urea formalin resin, polyethyleneimine, dicyandiamide formalin resin, and high molecular weight cationic amino resins such as cationic starch.

Of course, starch, pregelatinized starch, etherified starch, esterified starch, gelatin, collagen, viscose, casein, acacia, agar, sodium alginate, methylcellulose, ethylcellulose, carboxymethylcellulose, hydroxyethylcellulose, polyvinyl alcohol, carboxy-modified It is also possible to use binders known in the art, such as polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic acid, and polyacrylamide, and they are appropriately selected and used alone or in combination.

In the present invention, the method for preparing the coating liquid for the pigment coating layer is not particularly limited. Furthermore, as long as a pigment coating layer having a contact angle to water of 15 ° to 60 ° can be obtained, addition of various auxiliaries to the coating liquid for the pigment coating layer is optional, and if necessary, a water-proofing agent, Various auxiliaries such as a curing agent, a crosslinking agent, an antifoaming agent, a coloring agent, a wetting agent, a flow modifier, and a preservative are appropriately selected and added. The contact angle was measured based on the Tappi test method (T458 om-84). Distilled water was used for the measurement, and the drop amount was 5 μl, and the contact angle 60 seconds after the drop of the water droplet was dropped on the paper piece was taken as the measured value. If the contact angle is less than 15 °, the suitability for assembling the top paste is not sufficiently achieved. If the contact angle is more than 60 °, the ink for ink jetting does not easily permeate and the print density is reduced.

In the present invention, a plurality of sets of pressure-sensitive copying paper comprising upper paper and lower paper, or upper paper, at least one middle paper, and lower paper are stacked and used to glue one wall. A specific adhesive composition having a viscosity of 3 to 20 cps, a surface tension of 30 to 50 dyne / cm, and a solid content of 8 to 30% is selectively used as the paste to be formed. At this time, it is necessary to set the contact angle on the lower surface of the lower sheet to a specific range. If the contact angle is less than 70 °, sufficient grouping cannot be performed even if the specific adhesive composition is used. That is, the pigment coating layer of the upper paper is more easily permeated by the top paste than the surface of the base paper, so that it is difficult to group the pigments. But,
If the contact angle of water on the base paper surface of the lower paper in contact with the lower paper is 70 ° or more, the speed of penetrating the pigment coating layer of the upper paper becomes slow. Therefore, it becomes difficult for the adhesive to permeate as a whole. The larger the contact angle is, the more difficult it is to seep. There are many proposals for these specific adhesive compositions (JP-A-49-99635, JP-A-49-11).
9717, JP-A-49-125114, JP-A-50
-73928, JP-A-3-110190, JP-A-7-110190
No. -207242), and as the adhesive component, at least one selected from various water-soluble polymer components, various water-dispersible polymer components such as emulsions represented by polymer latex, hydrosols and the like is used. At this time, it is general that at least one or more of solvents such as alcohol and / or surfactants are appropriately selected and used. Further, various auxiliaries such as a plasticizer, a pH adjuster, a freeze stabilizer, and compounds known as desensitizers in the technical field may be appropriately selected and used.

The method for producing the microcapsules used in the present invention includes a so-called coacervation method and an interfacial polymerization method in which a polyurethane resin, a polyurea resin, a polyamide resin and the like are formed at the oil-water interface (Japanese Patent Publication No. Sho 42-446).
No., JP-B-42-771, JP-B-54-6506,
A known method such as an in-situ polymerization method represented by the use of a melamine-formaldehyde resin or a urea-formaldehyde resin can be arbitrarily used.

As the oil used for the core material of the microcapsules, natural or synthetic oils can be used alone or as a mixture, and examples thereof include cottonseed oil, kerosene, paraffin, naphthenic oil, alkylated biphenyl, and alkylated tar. So-called hydrophobic oils, such as dibasic acid esters such as phenyl, chlorinated paraffin, alkylated naphthalene, diarylalkane, and phthalic acid ester, are generally used, and at least one kind is appropriately selected and used.

As the electron-donating organic color former, at least one type is selected from known materials according to a desired color tone. For example, 3,3-bis (p-dimethylaminophenyl) -6-dimethyl Aminophthalide, 3,3-bis (p-dimethylaminophenyl) phthalide, 3- (p-
Triallylmethane compounds such as dimethylaminophenyl) -3- (1,2-dimethylindol-3-yl) phthalide, 4,4′-bis-dimethylaminobenzhydryl benzyl ether, N-halophenyl-leuco auramine , N-2,4,5-trichlorophenylleuco auramine and the like, 7-dimethylamino-3-chlorofluoran, 7-dimethylamino-3-
Chloro-2-methylfluoran, 2-phenylamino-
Fluorane compounds such as 3-methyl-6- (N-ethyl-Np-tolylaminofluoran), thiazine compounds such as benzoylleucomethylene blue and p-nitrobenzylleucomethylene blue, 3-methyl-spiro-dinaphthopyran, -Ethyl-spiro-dinaphthopyran, 3
-Propyl-spiro-dinaphthopyran, 3-propyl-
Spiro compounds such as spiro-dibenzopyran and the like can be mentioned.

Usually, the microcapsules for pressure-sensitive copying paper are prepared by dissolving the above-mentioned electron-donating organic color former and, if necessary, auxiliaries in a hydrophobic oil, emulsifying and dispersing in a hydrophilic liquid, and further heating and the like. Is produced through a reaction of forming a capsule wall film and / or a curing step. At this time, the use of an emulsifier is also generally known, for example, polyvinyl alcohol,
Protective colloids such as sulfonic acid-modified polyvinyl alcohol, gelatin, gum arabic, carboxymethylcellulose, casein, starch, styrene-maleic anhydride copolymer, isobutylene-maleic anhydride copolymer, polyacrylic acid, and alkylbenzene sulfonic acid, poly Ionic surfactants such as oxyethylene sulfate, funnel oil,
Further, nonionic surfactants such as polyoxyethylene alkyl ether, polyoxyethylene, sorbitan fatty acid ester and the like are used alone or in combination as necessary. Components necessary for forming the capsule wall film are appropriately selected according to the selected capsule preparation method, and are added to the hydrophobic liquid and / or the hydrophilic liquid.

The microcapsule coating liquid of the present invention may be prepared by mixing the microcapsules obtained above, a microcapsule buffer such as starch particles, cellulose powder, and the like.
Further, the binder is prepared by adding various binders. If necessary, various auxiliaries known in the field of pressure-sensitive copying paper production can be appropriately added.

As the color developer used in the present invention, one or more kinds are appropriately selected from known materials, and recently, an organic color developer is generally used. Examples of the organic developer include a novolak type phenol resin and a polyvalent metal salt thereof, and a salicylic acid derivative and a polyvalent metal salt thereof (Japanese Patent Publication No. 40-9309, Japanese Patent Publication No. 45-45).
14039, JP-A-48-51510, JP-A-52
1404043, JP-A-57-210886, JP-A-58-87089, JP-A-59-11286, JP-A-60-176799, JP-A-61-95988, and the like).

Examples of the phenolic raw materials for the phenolic resin include unsubstituted phenols, alkyl-substituted phenols (eg, cresol, ethylphenol, butylphenol, octylphenol, nonylphenol, etc., mainly para-substituted), aralkyl-substituted phenols (eg, Para-benzylphenol, para-cumylphenol, etc.),
And aryl group-substituted phenols (eg, para-phenylphenol).

Examples of the salicylic acid derivative include 3-phenylsalicylic acid, 5-phenylsalicylic acid, 3-benzylsalicylic acid, 5-benzylsalicylic acid, and 3- (α-
Methylbenzyl) salicylic acid, 5- (α-methylbenzyl) salicylic acid, 3- (α, α-dimethylbenzyl) salicylic acid, 5- (α, α-dimethylbenzyl) salicylic acid, 3,5-diphenylsalicylic acid, 3,5- Dibenzyl salicylic acid, 3,5-di (α-methylbenzyl) salicylic acid, 3,5-di (α, α-dimethylbenzyl) salicylic acid, 3,5-di (4-methylbenzyl) salicylic acid, benzylated styrenated salicylic acid And pinenated salicylic acid.

Further, specific examples of the polyvalent metal include magnesium, calcium, zinc, aluminum, iron, cobalt, nickel and the like. Of these, zinc is most preferably used.

The method for preparing the coating liquid for forming the color developing sheet is not particularly limited, but generally, a color developing agent, an inorganic and / or organic pigment, a binder, a dispersant and other auxiliaries, It is prepared by mechanically dispersing in water together with additives and the like. The organic developer is a method of dispersing into fine particles using various dispersers utilizing mechanical dispersing force, a developer containing an organic solvent added to an aqueous dispersion of an organic developer and / or Or a method of dispersing the organic solvent solution of the color developing agent into fine particles by emulsifying and dispersing the organic solvent solution in water using various dispersers, and then distilling off the organic solvent by a method such as steam distillation. In general, the suitability for pressure-sensitive copying paper is appropriately adjusted by prior processing.

The coating liquid for the pigment coating layer, the coating liquid for the microcapsule layer, and the coating liquid for the color developer layer thus prepared are paper,
Air knife coater on support such as synthetic paper, film, etc.
Coated by normal coating equipment such as blade coater, rod blade coater, roll coater, bar coater, size press coater, bill blade coater, curtain coater, short dwell coater, etc. as upper paper, middle paper, lower paper for pressure-sensitive copying paper Finished.

The coating amount on the support is not particularly limited as long as the effects of the present invention can be obtained. The coating amount of the pigment coating layer and the color developing agent layer is 1 to 20 g / m ² in terms of dry weight. And preferably ² to 10 g / m ² . The coating amount of generally microcapsule layer, 1.5~10g / m ² in dry weight, preferably 2-5 g / m ^2. Before applying the microcapsule coating liquid, the paper can be passed through an on or off super calender, a soft nip calender, or the like to perform pressure smoothing finish.

[0026]

EXAMPLES Examples and comparative examples are described below to further clarify the effects of the present invention, but the present invention is not limited to these examples. In the examples, “parts” and “%” represent “parts by weight” and “% by weight”, respectively, unless otherwise specified.

Example 1, Comparative Example 1 [Preparation of Coating Liquid for Pigment Layer] Kaolin (manufactured by EMC, UW-
90) 30 parts and 70 parts of light calcium carbonate (manufactured by Shiraishi calcium, Brilliant-15) were dispersed with a Cores disperser using 0.2 part of sodium polyacrylate as a dispersant, and a pigment slurry having a solid content of 65% was obtained. Obtained. 20 parts of a 25% aqueous solution of an oxidized modified starch and a solid content of 48 were added to the dispersion.
% Styrene-butadiene copolymer latex 30%
Part, as a cationic water-soluble polymer, a condensate of amine and epichlorohydrin having a solid content of 40% (Sumitomo Chemical Industries,
Sumireze Resin FR-2P) (5 parts) to give a solid concentration of 4
A 5% pigment layer coating solution was prepared.

[Preparation of microcapsule dispersion] 100 parts of diisopropylnaphthalene was added to 3-diethylamino-
7 parts of 6-methyl-7-anilinofluoran is heated and dissolved, and an aromatic polyvalent isocyanate (Millionate MR500 manufactured by Nippon Polyurethane Industry) is dissolved in the dye solution.
Trimer of hexamethylene diisocyanate having 4 parts and biuret bond which is aliphatic polyvalent isocyanate
4 parts were dissolved. This solution was added to 300 parts of a 2% aqueous solution of polyvinyl alcohol (manufactured by Kuraray, PVA-117) and emulsified by a homomixer to obtain a dispersion having an average particle size of 5 μm. To this dispersion, 2 parts of a polyamine composed of bisphenol A, epichlorohydrin and alkylamine was added, and the mixture was stirred at room temperature for 15 minutes.
The mixture was heated to ℃ and reacted for 4 hours. Thereafter, the mixture was cooled to room temperature to obtain a 40% microcapsule dispersion.

[Preparation of Microcapsule Layer Coating Liquid] 250 parts of the above microcapsule dispersion (solid content: 40%),
Water was added to a dispersion obtained by mixing 50 parts of wheat starch and 50 parts of a styrene-butadiene copolymer latex having a solid content of 48% as an adhesive to obtain a microcapsule layer coating liquid.

[Preparation of Upper Paper] The above-mentioned pigment layer coating liquid is applied to the surface of a base paper having a basis weight of 40 g / m ² by a blade coater so that the dry coating amount becomes 4 g / m ² and dried with hot air at 150 ° C. After that, the paper was passed through a super calender and subjected to a smoothing treatment. The coating liquid for the microcapsule layer was applied to the back surface of the pigment layer by an air knife coater so as to have a dry weight of 4 g / m ^2, and dried to prepare an upper paper for pressure-sensitive copying paper. The Bekk smoothness of the pigment layer surface based on JIS-P-8119 was 40 sec / 10 ml. The contact angle of the pigment layer with water was 22 °.

[Preparation of Coating Liquid for Developer Layer] 3,5-di (α
Toluene solution obtained by dissolving 10 parts of zinc salt of -methylbenzyl) salicylic acid in 10 parts of toluene at 70 ° C. was added to polyvinyl alcohol having a polymerization degree of 1700 and a saponification degree of 98%.
The mixture was emulsified in 30 parts of water containing 6 parts using a homomixer, and then toluene was distilled off by steam distillation to obtain an aqueous dispersion of developer fine particles. Into this aqueous dispersion, 90 parts of light calcium carbonate (Tamapearl TP-121, manufactured by Okutama Kogyo Kogyo Co., Ltd.) having a solid content of 65% dispersed in a Coreless disperser using 0.2 part of sodium polyacrylate as a dispersant, and oxidized modified starch 20 parts of a 25% aqueous solution of styrene-butadiene copolymer latex having a solid content of 48%, a polymerization degree of 500,
15% aqueous solution of polyvinyl alcohol with a saponification degree of 98% 3
0 parts were mixed to prepare a developer layer coating liquid (solid concentration: 45%).

[Preparation of Medium Paper] The above-mentioned developer layer coating liquid was applied to the surface of a base paper having a basis weight of 40 g / m ² by a blade coater so that the dry coating amount was 4 g / m ² , and hot air at 150 ° C. , And passed through a super calender to perform a smoothing treatment. The coating liquid for the microcapsule layer was applied to the back surface of the developer layer coated paper with an air knife coater so as to have a dry weight of 4 g / m ^2, and dried to prepare a medium for pressure-sensitive copying paper. . The Bekk smoothness of the surface of the color developer layer based on JIS-P-8119 was 40 sec / 10 ml.

[Preparation of Lower Paper] The above-described developer layer coating solution was applied to the surface of a high-quality paper having a basis weight of 40 g / m ² at a dry weight of 4 g / m 2.
^Two coatings were performed, and a super calender treatment was performed in the same manner as for the middle sheet to obtain a lower sheet for an example having a Beck smoothness of 80 sec / 10 ml and a contact angle of 78 ° on the back surface with water. Separately, except that another high-quality paper having the same basis weight was used, the same coating was performed to obtain a lower paper for a comparative example. The contact angle of the back surface with water was 60 °.

Example 2 In Example 1, a polyamine-polyamide-epichlorohydrin resin having a solid content of 25% (Sumitomo Chemical Industries, Sumireze Resin SR-1005) was used as the cationic water-soluble polymer in the pigment layer coating liquid. An upper sheet was obtained in the same manner as in Example 1 except that 8 parts were used. The contact angle of the pigment layer with water was 38 °. The same middle sheet as in Example 1 was used. The lower paper was obtained by coating in the same manner as in Example 1 except that another high-quality paper having the same basis weight was used. The contact angle of the back surface with water was 90 °.

Example 3 In Example 1, poly [N, N-dimethyl-N- (2-hydroxypropyl) ammonium salt] having a solid content of 40% was used as the cationic water-soluble polymer in the pigment layer coating liquid.
An upper paper was obtained in the same manner as in Example 1 except that 5 parts (Fix Oil R-737, manufactured by Meisei Chemical Industry Co., Ltd.) was used. The contact angle of the pigment layer with water was 18 °. The same middle and lower sheets as in Example 2 were used.

Example 4 In Example 1, 5.4 parts of a dicyandiamide formalin resin (manufactured by Nikka Chemical Co., Ltd., Neofix FY) having a solid content of 37% was used as the cationic water-soluble polymer in the pigment layer coating liquid. An upper sheet was obtained in the same manner as in Example 1 except for the above. The contact angle of the pigment layer with water was 21 °. The same middle and lower sheets as in Example 2 were used.

Example 5 In Example 1, as the cationic water-soluble polymer in the pigment layer coating liquid, a diallylamine-acrylamide copolymer having a solid content of 30% (Sumitomo Chemical Industries, Sumirezu Resin SR-1001) was used. Example 1 except that 6.7 parts were used
The upper paper was obtained in the same manner as described above. The contact angle of the pigment layer with water was 30 °. The same middle and lower sheets as in Example 2 were used.

Comparative Example 2 An upper sheet was obtained in the same manner as in Example 1 except that the cationic water-soluble polymer was not added. The contact angle of the pigment layer with water was 13 °. The same middle and lower sheets as in Example 1 were used.

Comparative Example 3 An upper paper was obtained in the same manner as in Example 1 except that calcium stearate was added as a water repellent to the pigment layer coating solution of Example 1 in an amount of 3 parts per 100 parts of white pigment. The contact angle of the pigment layer with water was 71 °. The same middle and lower sheets as in Example 1 were used.

[Measurement of Contact Angle] Tappi test method (T
458 om-84). Distilled water was used for the measurement, and the drop amount was 5 μl, and the contact angle 60 seconds after the drop of the water droplet was dropped on the paper piece was taken as the measured value.

[Evaluation of Print Suitability] Barcode printing was performed using an inkjet printer “6240” manufactured by Cytex Corporation, and the density and image quality of the printed matter were visually evaluated. (1) Concentration ○: Excellent. ×: There is a problem in practical use. (2) Image quality ：: Excellent. ×: Feathering and the like are present.

[Evaluation of suitability for paste] Equal amounts of polyester-modified urethane resin emulsion (average particle size: 0.2 μm, nonvolatile content: 40%) and acrylic acid / acrylate copolymer water-soluble resin (volatile content: 32%) One part of a nonionic surfactant (HLB 12.6) and dilution water were added to the mixture to obtain an adhesive composition having a viscosity of 7 cps, a surface tension of 37 dyne / cm, and a solid content of 17%. After combining each of the upper paper, the middle paper, and the lower paper of Examples 1 to 5 and Comparative Examples 1 to 3 as a set, and stacking and cutting the same to 20 to 30 cm,
An adhesive composition prepared in advance was applied to one side wall surface using a brush, and dried at room temperature. One hour after drying, the sheets were separated, and the adhesive strength between the sheets and the suitability for grouping of each set were evaluated. Table 1 shows the results. (1) Adhesive strength ：: Excellent. Δ: Practically problematic. X: Poor adhesion. (2) Suitability for grouping ：: Excellent. Δ: There is some problem in grouping. ×: Poor grouping.

[0043]

[Table 1] * Number of parts added in terms of solid content

Examples 6 to 9 and Comparative Examples 4 to 8 The ratio and concentration of both polymers used in the evaluation of the suitability for the above-mentioned paste, and the H of nonionic surfactant used as an auxiliary agent
The desired adhesive composition having the physical properties shown in Table 2 was obtained by appropriately adjusting the LB and the amount of addition. Except for using this adhesive composition, evaluation of suitability for pad was conducted in the same manner as in Example 1. Table 2 shows the results.

[Measurement of surface tension] Solid content concentration is 1% by weight
This is a value measured at 25 ° C. by a Denoy surface tensiometer on a sample 8 hours after the preparation of the aqueous adhesive solution, and is a value corrected with distilled water at 72 dyne / cm. More specifically, it was calculated as follows. The platinum ring of the Dinui surface tension meter was brought into contact with the liquid surface of the measurement solution, the platinum ring was lifted, and the value at the time when the platinum ring was separated from the liquid surface was read. At the same time, the value of distilled water was measured in the same manner. At this time, since there is a proportional relationship between the measured value and the surface tension,
The surface tension of the measurement solution was calculated by taking a correction value by setting the surface tension of distilled water to 72 dyne / cm.

[0046]

[Table 2]

[0047]

As is clear from Tables 1 and 2, the pressure-sensitive copying paper obtained in the examples of the present invention is excellent in the recording suitability of the ink jet recording system suitable for high-speed printing, and has been conventionally used in the form. The aptitude suitability required as a paste was also good.

[Procedure amendment]

[Submission date] September 18, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0043

[Correction method] Change

[Correction contents]

[0043]

[Table 1] * Number of parts added in terms of solid content

Claims (4)

[Claims] 1. An upper paper and a lower paper, or an upper paper, a large number of at least one middle paper and a lower paper, utilizing a color development reaction between an electron-donating organic color former and an electron-accepting developer. In the pressure-sensitive copying paper used in combination of the sheets, the upper paper having a pigment coated layer containing a pigment and a cationic water-soluble polymer and having a contact angle to water of 15 ° to 60 ° on the front surface, Pressure-sensitive copying paper characterized in that it is used in combination with lower paper having a contact angle with water of 70 ° or more. 2. The pressure-sensitive copying paper according to claim 1, wherein the cationic water-soluble polymer is a condensate of an amine and epichlorohydrin. 3. A plurality of sets of pressure-sensitive copying paper according to claim 1 or 2, comprising upper paper and lower paper, or upper paper, at least one middle paper, and lower paper, and using an adhesive composition. A pressure-sensitive copying paper set characterized in that one side wall is glued. 4. The pressure-sensitive copying paper set according to claim 3, wherein the adhesive composition has a viscosity of 3 to 20 cp, a surface tension of 30 to 50 dyne / cm, and a solid content of 8 to 30% by weight.