JPH0648019A - Pressure-sensitive copying sheet - Google Patents

Abstract

PURPOSE:To obtain a pressure-sensitive copying sheet which contains a capsule ink enveloping an electron-donative coloring agent on one surface of a sheet and displays excellent color development properties, if the capsule ink is used for type printing or offset printing. CONSTITUTION:The pressure-sensitive copying sheet is obtained by printing an ink which contains a microcupsule enveloping an electron-donative coloring agent on one surface of a support. In addition, the copying sheet uses a sheet with an air permeability of 35'' max based on JIS-P-8117 or a sheet with a pigment-coated layer on one surface as a support. Further, the copying sheet undergoes type printing or offset printing of the capsule ink on the sheet surface of the support.

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 obtained by printing a capsule ink containing an electron-donating color former on one side of a sheet.

[0002]

2. Description of the Related Art Electron-donating color formers such as crystal violet lactone and benzoyl leuco methylene blue,
Pressure-sensitive copying paper utilizing the principle of developing color by reaction with an electron-accepting color developer such as activated clay, phenolic resin, and polyvalent metal salt of salicylic acid derivative is well known.

Generally, such a pressure-sensitive copying paper is produced by a phase separation method,
Top paper coated with a color-forming agent-encapsulated microcapsule prepared by a method such as an interfacial polymerization method or an in-situ method on the back surface of the support, a bottom paper coated with a developer on the support, the microcapsule and the developer. Practical papers in which the above-mentioned materials are coated on different surfaces of the support are appropriately combined and put to practical use. The capsule layer of such a pressure-sensitive copying paper is usually prepared by applying an aqueous capsule coating solution onto a support with a large coating machine (hereinafter referred to as coating method).
Formed by. As a special manufacturing method, there is a method of converting the capsule into an ink and coating it on a support with a printing machine (hereinafter referred to as a printing method).

The printing method is suitable for the production of a large number of products in a small amount as compared with the coating method because it can produce even a small lot in a small amount of loss, and for example, it is a pressure sensitive pressure of a special coloring color which tends to be small in a lot. Suitable for producing copy paper.
In addition, the printing method is more economical than the coating method in which expensive capsules are applied to the entire surface of the support because the capsules can be partially printed only on the necessary portions of the support. The printing method is as follows: partial printing of capsule inks of different color tone on high quality paper or on the back surface of the lower paper, or on the upper paper coated entirely by the coating method as described in JP-A-1-301360. Various printing such as pressure-sensitive copying paper (upper paper or middle paper) having a plurality of color-developing color tones can be obtained by partially printing a capsule ink having a color-developing color different from that of the capsule on the coated surface of the medium paper. It is possible to produce varieties with characteristics.

As described above, the printing method is a production method having many merits, but it cannot be said to be sufficient in terms of quality as a pressure-sensitive copying paper. That is, when a top sheet is prepared by printing a letterpress type or offset type capsule ink on one surface of a sheet having air permeability such as high quality paper, only a copy paper having a poor coloring property can be obtained.

[0006]

The present inventors have found that such a problem is caused by the fact that when printing in a letterpress type or an offset type, the ink medium remains on the surface and hardens without penetrating into the sheet, and the It was speculated that the oil release property would deteriorate, and as a result of repeated research, a sheet showing extremely low air permeability that would not be suitable for normal pressure-sensitive copying paper was used. Alternatively, it has been found that by offset printing, it is possible to obtain pressure-sensitive copying paper with good color development, which has not been achieved so far.
Finally, the present invention has been completed.

[0007]

The present invention provides a pressure-sensitive copying paper obtained by printing an ink containing microcapsules containing an electron-donating color-forming agent on one side of a support, and the support according to JIS P 8117. Based on a base paper having an air permeability of 35 seconds or less, or a sheet having a pigment coating layer on one side of the base paper,
The pressure-sensitive copying paper is characterized by being obtained by letterpress printing or offset printing a microcapsule ink on the base paper surface of the support.

[0008]

The base paper used in the present invention is acid paper obtained by making fibers such as natural pulp or synthetic pulp.
Among the breathable sheets such as neutral paper and synthetic paper, JISP
The value of the air permeability based on 8117 is 35 seconds or less, and the preferable value is the range of 5 to 25 seconds. By the way, when a base paper with an air permeability of more than 35 seconds is used, the ink medium of the capsule ink does not penetrate into the sheet and remains on the surface and hardens, so the oil release from the capsule deteriorates and the color is developed. Only copy paper with bad performance can be obtained.

A pigment coating layer may be formed on one side of the sheet. The coating liquid used to form the pigment coating layer is prepared by using a film-forming material and a pigment as basic components, and as the film-forming material, a water-soluble polymer or latex is usually used. Used alone or in combination. Examples of the water-soluble polymer include starch, casein, sodium alginate, gum arabic, phosphorylated starch, oxidized starch, carboxymethyl cellulose, sodium polyacrylate, polyvinyl alcohol, hydroxyethyl cellulose, polyvinylpyrrolidone, polyacrylic acid amide, methyl vinyl ether- Maleic anhydride copolymer,
Ethylene-maleic anhydride copolymer, vinyl acetate-maleic anhydride copolymer, styrene-maleic anhydride copolymer, isobutylene-maleic anhydride copolymer, methacrylamide-maleic anhydride copolymer, methyl acrylate -Acrylic acid copolymer, ethyl acrylate-acrylic acid copolymer, methyl acrylate-methacrylic acid copolymer, methyl methacrylate-acrylic acid copolymer, methyl methacrylate-methacrylic acid copolymer, methyl acrylate -Acrylamide-acrylic acid copolymer, acrylonitrile-acrylic acid copolymer, acrylonitrile-methacrylic acid copolymer, hydroxyethyl acrylate-acrylic acid copolymer, hydroxyethyl acrylate-methacrylic acid copolymer, vinyl acetate-acrylic acid Copolymer, vinyl acetate-methacrylate Acid copolymer, acrylamide-acrylic acid copolymer, acrylamide-methacrylic acid copolymer, methacrylamide-acrylic acid copolymer, methacrylamide-methacrylic acid copolymer, vinyl acetate-crotonic acid copolymer, vinyl acetate -Acrylic acid-maleic acid copolymer, vinyl acetate-methacrylic acid-maleic acid copolymer, vinyl acetate-ethyl acrylate-maleic acid copolymer, methyl acrylate-vinylbenzene sulfonic acid copolymer, vinyl acetate- Examples thereof include vinylbenzene sulfonic acid copolymer. These are used alone or in combination. Among the water-soluble polymers, anionic ones can also be used as metal salts or ammonium salts.

Examples of the latex include styrene-butadiene latex, acrylonitrile-butadiene latex, acrylic latex, vinyl acetate latex and carboxy-modified latex thereof. These are used alone or in combination.

Examples of the pigment include light calcium carbonate, heavy calcium carbonate, aluminum hydroxide, zinc oxide, titanium oxide, calcium sulfate, silica, kaolin,
Examples include white pigments such as calcined kaolin and satin white. These are used alone or in combination.

In addition to the above components, the pigment coating layer coating liquid may contain a dispersant, a surfactant, a defoaming agent, a thickener, a preservative, a release agent, a fluorescent brightening agent, and an ultraviolet absorbing agent, if necessary. Agent, antioxidant,
Various auxiliaries known in the field of coated papers such as colored dyes are added and mixed with stirring, and usually prepared as an aqueous coating liquid. still,
A film-forming material such as a water-soluble polymer or latex is usually added in an amount of 10 to 50% by weight, and a pigment is added in an amount of 50 to 90% by weight based on the coating solid content.

The coating liquid thus prepared is usually used in various coating machines such as an air knife coater, a bar coater, a roll coater, a blade coater, a gravure coater and a curtain coater, and is usually 1 to 30 g / m ² , preferably on one side of the base paper. Is smeared in a range of 3 to ²⁰ g / m ² . The smeared sheet is subjected to a super calendering process if necessary.

In the present invention, when the capsule ink is printed on the pigment-coated paper, it is printed on the base paper surface. However, when it is provided on the pigment-coated layer, the ink medium of the capsule ink penetrates. Since it is difficult to do so, the color developability deteriorates.

Electron-donating color formers used in capsule inks are known in the art, such as 3,
3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3- (p-dimethylaminophenyl) -3- (1,2-dimethylindol-3-yl)
Phthalide, 3,3-bis (1,2-dimethylindol-3-yl) -5-dimethylaminophthalide, 3,3-
Triallylmethane dyes such as bis (9-ethylcarbazol-3-yl) -6-dimethylaminophthalide, 4,
4-bis-dimethylaminobenzhydrylbenzyl ether, N-halophenyl leuco auramine, N-2,
Diphenylmethane dyes such as 4,5-trichlorophenylleuco auramine, benzoyl leuco methylene blue, thiazine dyes such as P-nitrobenzoyl leuco methylene blue, 3-methyl-spiro-dinaphthopyran,
Spiro dyes such as 3-phenyl-spiro-dinaphthopyran and 3-propyl-spiro-dibenzopyran, lactam dyes such as rhodamine-B-anilinolactam and rhodamine (o-chloroanilino) lactam, 3-dimethylamino-7- Methoxyfluorane, 3-diethylamino-
6-methyl-7-chlorofluorane, 3- (N-ethyl-p-toluidino) -7-methylfluorane, 3-diethylamino-7-N-methylaminofluorane, 3-diethylamino-7-dibenzylamino Fluoran, 3-
(N-ethyl-p-toluidino) -6-methyl-7-phenylaminofluorane, 3-diethylamino-6-methyl-7-phenylaminofluorane, 3- (N-cyclohexyl-N-methylamino) -6 -Methyl-7-phenylaminofluorane, 3-piperidino-methyl-7
-Phenylaminofluorane, 3-diethylamino-6
Fluorane dyes such as -methyl-7-xylidinofluorane, 3,3-bis [2- (p-dimethylaminophenyl) -2- (p-methoxyphenyl) ethylene-2-yl] -4,5, Infrared absorption dyes such as 6,7-tetrachlorophthalide can be used, and these can be used alone or in combination.

The above-mentioned electron-donating color former is usually encapsulated in a state of being dissolved in oil, and examples of such oil include the following substances known in the art. Vegetable oils such as cottonseed oil; kerosene, paraffin, naphthenic oil,
Mineral oils such as chlorinated paraffins; alkylated biphenyls, alkylated terphenyls, alkylated naphthalenes,
Aromatic hydrocarbons such as diarylethane, triarylmethane, diphenylalkane; dimethyl phthalate, diethyl phthalate, di-n-butyl phthalate,
Esters such as dioctyl phthalate, diethyl adipate, propyl adipate, di-n-butyl adipate, dioctyl adipate, and the like, and mixtures thereof. The electron-donating color former is usually 2 to 100 parts by weight of oil.
The amount is 80 parts by weight, preferably 5 to 50 parts by weight.

As the encapsulation method, known coacervation method, interfacial polymerization method, in-situ method and the like can be appropriately selected and used. Among them, a melamine-formalin resin film obtained by the in-situ method is used. Capsules are particularly preferable because they have excellent solvent resistance and are easy to be powdered. The average particle size of the capsule varies depending on the film material used or the film thickness and cannot be generally stated, but it is usually 1 to 1
It is 0 μm. Further, the capsule may contain an antioxidant and an ultraviolet absorber, if necessary.

The aqueous capsule dispersion liquid obtained by the above method is untreated or filtered, for example, dried by aeration,
Surface drying, fluidized drying, air stream drying, spray drying, vacuum drying,
Freeze-drying, infrared-drying, high-frequency drying, ultrasonic drying, fine pulverization, etc. are processed into powder capsules, which are then dispersed in the ink medium, and various auxiliary agents are added as necessary to prepare capsule inks. It Further, a cake-like material obtained by filtering the aqueous capsule dispersion liquid is mixed with an ink medium, and various auxiliaries are further added, if necessary, to prepare a capsule ink. Further, the cake-like material obtained by filtering the aqueous capsule dispersion is mixed with the ink medium, water contained therein is removed under reduced pressure, and various auxiliaries are added as necessary to prepare a capsule ink.

As a device used for mixing or dissolving capsules and various auxiliaries in the ink medium, those known in the ink industry can be used, and among them, a high speed stirrer such as Corless, a homomixer and a roll mill are preferably used. . Examples of the ink medium used for the letterpress type or offset type capsule ink include various mediums known in the ink industry, for example, a high boiling point medium in the case of permeation drying type ink and an oil in the case of oxidation polymerization type ink. In the case of the class and UV curable ink, a compound having at least one vinyl group or vinylidene group in the molecule is used.

Examples of the high boiling point medium used in the permeation-drying type ink include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, 2,3-butylene glycol, methyl cellosolve,
Cellosolve, butyl cellosolve, carbitol, butyl carbitol and the like can be mentioned.

When a high boiling medium is used, a resin for fixing the capsule to the support is usually used. Examples of the resin include gum rosin, wood rosin, shellac, ester gum, pentaerythritol ester of rosin, pentaerythritol ester of polymerized rosin, maleic acid resin, pentaerythritol ester of maleated rosin, dimerized rosin, rosin-modified phenolic resin, butanol-modified Urea resin, butanol modified melamine resin, terpene resin, terpene phenol resin, soybean oil modified alkyd resin, polyamide resin, polyvinyl acetate,
Acrylic resin, vinyl chloride, vinyl chloride / vinyl acetate copolymer, ethylene-maleic anhydride copolymer, styrene-maleic anhydride copolymer, methyl vinyl ether-maleic anhydride copolymer, isobutylene-maleic anhydride copolymer Examples include coalesce, modified polyvinyl alcohol, polyvinyl butyral, polyvinyl pyrrolidone, ethyl cellulose, nitrocellulose, hydroxypropyl cellulose, cellulose acetate propionate, cellulose acetate butyrate and the like.

In the case of the permeation-drying type ink, in addition to the above-mentioned high boiling point medium and resin, if necessary, cellulose powder, starch particles, stilt materials such as synthetic resin particles, and desensitizing components for color development such as desensitizing agents. A white pigment such as titanium oxide or surface-treated titanium oxide, an ultraviolet absorber, an antioxidant, a fluorescent whitening agent, a plasticizer, a coloring dye, a thixotropy imparting agent and the like can be added.

The capsule content in the capsule ink is usually adjusted to a range of 5 to 50 parts by weight with respect to 100 parts by weight of the ink. Also, the content of the ink medium is 1
It is prepared in the range of 30 to 90 parts by weight with respect to 00 parts by weight. Examples of oils used as a medium for the oxidation polymerization type ink include vegetable oils such as linseed oil, safflower oil, soybean oil and castor oil: dehydrated castor oil, polymerized oil, maleated oil,
Processing oils such as vinyl oil and urethane oil: machine oil, mineral oil such as spindle oil, and the like.

In the case of the oxidative polymerization type ink, in addition to the above oils, if necessary, a tilting material such as cellulose powder, starch particles, synthetic resin particles, a desensitizing component for color development such as a desensitizing agent, titanium oxide, Add white pigment such as surface treated titanium oxide, UV absorber, antioxidant, fluorescent whitening agent, plasticizer, coloring dye, thixotropic agent, solvent, wax, dryer, thickener, gelling agent, etc. You can The capsule content in the capsule ink is usually adjusted to a range of 5 to 50 parts by weight with respect to 100 parts by weight of the ink. or,
The content of the ink medium is usually adjusted in the range of 30 to 90 parts by weight with respect to 100 parts by weight of the ink.

Examples of the compound having one or more vinyl group or vinylidene group in the molecule used as a medium for the ultraviolet curable ink include acryloyl group, methacryloyl group, allyl group, unsaturated polyester, vinyloxy and acrylamide group. Examples thereof include a reaction product of a polyol, a polyamine or an amino alcohol, and the like, and an unsaturated carboxylic acid, and a reaction product of a hydroxyl group-containing acrylate or methacrylate with a polyisocyanate. Representative compounds include, for example, polyethylene glycol diacrylate, propylene glycol dimethacrylate, pentaerythritol triacrylate, trimethylolpropane diacrylate, trimethylolpropane triacrylate, pentaerythritol tetraacrylate, hexanediol diacrylate,
1,2-butanediol diacrylate, reaction product of epoxy resin and acrylic acid, reaction product of pentaerythritol and methacrylic acid, acrylic acid, reaction product of diethylene glycol and maleic acid, acrylic acid, methyl methacrylate, butyl methacrylate, Examples include styrene and the like.

When the above compound is used, it is necessary to add a photopolymerization initiator at the same time, and a sensitizer may be added if necessary. Examples of the photopolymerization initiator include benzoquinone, phenanthrenequinone, naphthoquinone,
Aromatic ketones such as diisopropylphenanthrenequinone, benzoisobutyl ether, benzoin, furoin butyl ether, Michler's ketone, Michler's thioketone, fluorenone, trinitrofluorenone, β-benzoylaminonaphthalene, quinone compounds, ether compounds,
A nitro compound is mentioned.

Examples of the sensitizer include triethanolamine, N-methyldiethanolamine, N, N-dimethylethanolamine, N-methylmorpholine and the like. In the case of UV curable ink, in addition to the above, cellulose powder, starch particles, synthetic resin particles and other tilting materials, desensitizing components such as desensitizing components for color development, titanium oxide, surface treated titanium oxide, etc. White pigments, antioxidants, optical brighteners, plasticizers, coloring dyes, thixotropic agents,
Thickeners, resins, oils, high boiling point media, waxes, dryers, thickeners, gelling agents and the like can be added.

The capsule content in the capsule ink is usually adjusted to 5 to 50 parts by weight with respect to 100 parts by weight of the ink. Also, the content of the ink medium is 1
It is prepared in the range of 30 to 90 parts by weight with respect to 00 parts by weight. An ultraviolet irradiation device such as a high pressure mercury lamp is usually used for drying the ink.

The permeation drying type, oxidation polymerization type and ultraviolet curing type capsule inks used in the present invention are particularly preferably those having a viscosity of 15,000 cps or less, but especially preferable are those in the range of 2000 to 10,000 cps. Is. Incidentally, the effect of the present invention is weakened when an ink having a viscosity higher than 15,000 cps is used.

The prepared permeation-drying type, oxidation-polymerizing type, and UV-curing type capsule inks are usually used in letterpress and offset printing, and usually have a dry weight of 2 to 10 g / on the base paper surface of the sheet.
The coating amount is m ² and preferably 3 to 6 g / m ² .

The top paper of the present invention thus obtained is used in combination with pressure-sensitive copying paper such as middle paper and bottom paper, for example, and the electron-accepting developer layer of such a sheet is formed. Examples of the electron-accepting developer layer used in the above include clays such as acid clay and activated clay, phenolic resins, polyvalent metal salts of various aromatic carboxylic acids described in JP-B-51-25174, JP Materials known in the art such as zinc salt of 2,2-bisphenol sulfone compound described in JP-A No. 54-106316 can be used, and they can be used alone or in combination.

The coating liquid containing the electron-accepting developer includes, in addition to the above-mentioned electron-accepting developer, a film-forming material such as the above-mentioned water-soluble polymer or latex, and if necessary, the above-mentioned material. Such as a pigment, a starch material such as a starch particle or a pulp powder, an oil capsule acting as a color sensitizer, a dispersant, a surfactant, a defoaming agent, a thickener, a preservative, a release agent, an optical brightener, It is prepared as an aqueous coating liquid by adding and mixing various auxiliaries such as an ultraviolet absorber, an antioxidant and a colored dye under stirring. Above all, the addition of oil capsules is particularly preferable because of good color development.

Usually, the electron-accepting developer is 2% of the coating solid content.
-80% by weight, and the film forming material is blended in the range of 5-40% by weight. The pigment is blended in the range of 0 to 90% by weight and the oil capsule is blended in the range of 0 to 40% by weight. The coating solution thus prepared is usually applied to the base paper with various coating machines such as an air knife coater, a bar coater, a roll coater, a blade coater, a gravure coater and a curtain coater.
To 30 g / m ^2, it is applied preferably to be in the range of 3 to 10 g / m ^2. The smeared sheet is subjected to a super calendering process if necessary.

On the other hand, the capsule coating liquid used for forming the capsule layer of the medium paper is the above-mentioned capsule dispersion liquid.
Further, if necessary, the film forming material, the tilting agent,
Dispersants, surfactants, defoamers, thickeners, preservatives, pigments,
It is prepared as an aqueous coating liquid by adding various additives such as a releasing agent, a fluorescent whitening agent, an ultraviolet absorber, an antioxidant, a colored dye and the like with stirring under mixing. Usually, capsules have 20 to 1 paint solids
The amount of the film forming material is 0 to 50% by weight, and the tilt material is 0 to 60% by weight.

The coating solution thus prepared is usually coated on the back surface of the developer coated paper with various coating machines such as an air knife coater, a bar coater, a roll coater, a gravure coater and a curtain coater, usually at 1 to 30 g / m ^2. , Preferably 3
It is applied in the range of 10 to 10 g / m ² .

"Examples" Examples and comparative examples are given below in order 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 (Preparation of capsule ink) 3,3-bis (2-methyl-)
25 parts of 1-octyl-3-indolyl) phthalide was dissolved in 75 parts of benzyltoluene by heating to obtain an internal phase oil. Subsequently, the internal phase oil was emulsified in 200 parts of a 3% aqueous solution of an ethylene-maleic anhydride copolymer (trade name: EMA-31, manufactured by Monsanto) whose pH was adjusted to 6.0, and this system was The temperature was raised to 55 ° C. Separately, 15 parts of melamine was added to 45 parts of 37% aqueous formaldehyde solution, and the mixture was reacted at 60 ° C. for 15 minutes to prepare a prepolymer aqueous solution. This prepolymer aqueous solution was added dropwise to the emulsion, 0.1N hydrochloric acid was added dropwise with stirring to adjust the pH to 5.3, the system was heated to 80 ° C. and stirred for 1 hour. Then, 0.2N hydrochloric acid was added dropwise to lower the pH to 3.5, and the mixture was stirred for 3 hours and then cooled to obtain a dispersion liquid of capsules having an average particle diameter of 3.0 μm. Next, this dispersion was filter-pressed, and then 25 parts of this capsule (solid content), 5 parts of benzoin methyl ether, 0.3 part of triethanolamine and 1 part of colloidal silica were mixed with an ethylenically unsaturated compound (63
(0 cps, 25 ° C.) 69 parts were mixed and dispersed using a high-speed stirrer (Choles), water was removed under reduced pressure, and then the mixture was mixed using a three-roll mill to give a viscosity of 4500 cps (25
(° C) ink was obtained.

(Preparation of Top Paper) The above capsule ink was letterpress-printed (ink amount 5.0 g / m ² ) on 40 g / m ² base paper having an air permeability of 13 seconds according to JIS P 8117, and a 6 kw high-pressure mercury lamp. Was used to cure the ink to obtain a top paper.

(Preparation of Oil Capsule) Ethylene-maleic anhydride copolymer (trade name: adjusted to pH 6.0)
After emulsifying 100 parts of alkyldiphenylethane as an internal phase oil in 200 parts of a 3% aqueous solution of EMA-31, manufactured by Monsanto Co., Ltd., this system was heated to 55 ° C. Separately, add 15 parts of melamine to 45 parts of 37% formaldehyde aqueous solution,
An aqueous prepolymer solution was prepared by reacting at 60 ° C. for 15 minutes. This prepolymer aqueous solution was added dropwise to the emulsion, 0.1N hydrochloric acid was added dropwise with stirring to adjust the pH to 5.3, the system was heated to 80 ° C. and stirred for 1 hour. Then, 0.2N hydrochloric acid was added dropwise to lower the pH to 3.5, and the mixture was stirred for 3 hours and then cooled to obtain a dispersion liquid of capsules having an average particle diameter of 4.5 μm.

(Preparation of color paper) Light calcium carbonate 60
Parts, 10 parts of zinc oxide, 10 parts of a blended product of zinc 3,5-di (α-methylbenzyl) salicylate and an α-methylstyrene-styrene copolymer (blending ratio 80/20), the oil capsule 10 described above. Part, 0.2 parts of pulp powder 10 parts
Disperse in 300 parts of an aqueous polyvinyl alcohol solution, and further add 10 parts of gelatinized starch (solid content), 15 parts of carboxy-modified styrene-butadiene latex (solid content), 1 part of carboxymethyl cellulose and 1 part of hydroxyethyl cellulose with stirring and then dilute. The resulting 30 wt% developer coating solution was applied to 40 g / m ² base paper with an air knife coater so that the dry weight was 7 g / m ² to obtain a developer paper. (Evaluation) When the above-mentioned upper paper and the color-developing paper were overlaid and printed with a typewriter, a very good color image was obtained.

Example 2 (Preparation of top paper) A 40 g / m ² base paper having an air permeability of 22 seconds was letterpress-printed (ink amount 5.0 g / m ² ) with the capsule ink obtained in the same manner as in Example 1. The ink was cured using a 6 kw high pressure mercury lamp to obtain an upper paper. (Evaluation) When the above-mentioned upper paper and the color-developing paper obtained in the same manner as in Example 1 were overlapped and printed with a typewriter, a very good color image was obtained.

Example 3 (Preparation of top paper) A 40 g / m ² base paper having an air permeability of 33 seconds was letterpress-printed (ink amount 5.0 g / m ² ) with the capsule ink obtained in the same manner as in Example 1. The ink was cured using a 6 kw high pressure mercury lamp to obtain an upper paper. (Evaluation) When the above-mentioned upper paper and the color developing paper obtained in the same manner as in Example 1 were overlapped and printed with a typewriter, a good color image was obtained. However, it was inferior to Example 1.

Example 4 (Preparation of Pigment Coated Paper) 100 parts of light calcium carbonate was dispersed in 100 parts of a 0.2% aqueous solution of sodium polyacrylate, and further 10 parts of gelatinized starch (solid content) and carboxy-modified styrene. 30 parts by weight of a butadiene latex (solid content) was added under stirring and then diluted to obtain a 30% by weight white pigment coating liquid. Apply this white pigment coating solution to 40% air permeability
A pigment-coated paper was obtained by smearing the g / m ² base paper with an air knife coater so that the dry weight was 8 g / m ^2, and then supercalendering. (Preparation of Top Paper) The capsule ink obtained in the same manner as in Example 1 was letterpress-printed (ink amount 5.0 g / m ² ) on the base paper surface of the above pigment-coated paper, and the ink was printed using a 6 kw high-pressure mercury lamp. Was cured to obtain a top paper. (Evaluation) When the above-mentioned upper paper and the color-developing paper obtained in the same manner as in Example 1 were overlapped and printed with a typewriter, a very good color image was obtained.

Example 5 (Preparation of Pigment Coated Paper) A white pigment coating solution obtained in the same manner as in Example 4 was applied to 40 g / m ² base paper having an air permeability of 33 seconds to give a dry weight of 8 g / m ² . It was smeared with an air knife coater so that it was treated with a super calender to obtain a pigment coated paper. (Preparation of Top Paper) The capsule ink obtained in the same manner as in Example 1 was letterpress-printed (ink amount 5.0 g / m ² ) on the base paper surface of the above pigment-coated paper, and the ink was printed using a 6 kw high-pressure mercury lamp. Was cured to obtain a top paper. (Evaluation) When the above-mentioned upper paper and the color developing paper obtained in the same manner as in Example 1 were overlapped and printed with a typewriter, a good color image was obtained. However, it was inferior to Example 4.

Example 6 (Preparation of Top Paper) The capsule ink obtained in the same manner as in Example 1 was offset printed (ink amount: 4.5 g / m ² ) on a 40 g / m ² base paper having an air permeability of 13 seconds. The ink was cured using a 6 kw high pressure mercury lamp to obtain an upper paper. (Evaluation) When the above-mentioned upper paper and the color-developing paper obtained in the same manner as in Example 1 were overlapped and printed with a typewriter, a very good color image was obtained.

Comparative Example 1 (Preparation of Top Paper) Capsule ink obtained in the same manner as in Example 1 was letterpress-printed (ink amount 5.0 g / m ² ) on 40 g / m ² base paper having air permeability of 45 seconds. The ink was cured using a 6 kw high pressure mercury lamp to obtain an upper paper. (Evaluation) When the above-mentioned upper paper and the color-developing paper obtained in the same manner as in Example 1 were overlapped and printed by a typewriter, the color image was inferior.

Comparative Example 2 (Preparation of Top Paper) Capsule ink obtained in the same manner as in Example 1 was letterpress-printed (ink amount 5.0 g / m ² ) on 40 g / m ² base paper having an air permeability of 75 seconds. The ink was cured using a 6 kw high pressure mercury lamp to obtain an upper paper. (Evaluation) When the above-mentioned upper paper and the color developing paper obtained in the same manner as in Example 1 were overlapped and printed by a typewriter, the color image was extremely inferior.

Comparative Example 3 (Preparation of Pigment Coated Paper) A white pigment coating solution obtained in the same manner as in Example 4 was applied to 40 g / m ² base paper having an air permeability of 75 seconds to give a dry weight of 8 g / m ² . It was smeared with an air knife coater so that it was treated with a super calender to obtain a pigment coated paper. (Preparation of Top Paper) The capsule ink obtained in the same manner as in Example 1 was letterpress-printed (ink amount 5.0 g / m ² ) on the base paper surface of the above pigment-coated paper, and the ink was printed using a 6 kw high-pressure mercury lamp. Was cured to obtain a top paper. (Evaluation) When the above-mentioned upper paper and the color developing paper obtained in the same manner as in Example 1 were overlapped and printed by a typewriter, the color image was extremely inferior.

Comparative Example 4 (Preparation of Top Paper) The capsule ink obtained in the same manner as in Example 1 was offset-printed (ink amount 4.6 g / m ² ) on 40 g / m ² base paper having an air permeability of 45 seconds. The ink was cured using a 6 kw high pressure mercury lamp to obtain an upper paper. (Evaluation) When the above-mentioned upper paper and the color-developing paper obtained in the same manner as in Example 1 were overlapped and printed by a typewriter, the color image was inferior.

[0050]

EFFECTS OF THE INVENTION The pressure-sensitive copying paper of the present invention in which the capsule ink is letterpress-printed or offset-printed is extremely excellent in color development.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shunsuke Shioi 4-3-1 Jōkoji, Amagasaki City, Hyogo Prefecture Kanzaki Paper Co., Ltd. Kanzaki Mill

Claims (1)

[Claims] 1. A pressure-sensitive copying paper obtained by printing an ink containing an electron-donating color-forming agent-encapsulating microcapsule on one side of a support, wherein the support has an air permeability of 35 seconds or less according to JIS P 8117. A pressure-sensitive copying paper obtained by using a base paper or a sheet having a pigment coating layer on one side of the base paper, and by letterpress printing or offset printing the capsule ink on the base paper side of the support.