JP2504803B2 - Pressure-sensitive recording sheet - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a pressure-sensitive copying sheet, and in particular, to a feeling obtained by printing a capsule ink on the back surface of a sheet provided with a layer containing a chromogenic substance. The present invention relates to improvement of a pressure copying sheet.

"Prior art" A combination of an electron-donating color former such as crystal violet lactone and benzoyl leuco methylene blue, and an electron-accepting developer such as activated clay, phenol formaldehyde condensate, and a polyvalent metal salt of an aromatic carboxylic acid, Alternatively, various chromogenic substances such as nickel carboxylic acid salts and N, N′-di-benzyl-di-thio-oxamide, iron phosphate organic salts and metal salts such as lauryl gallate and ligand compounds can be used. Pressure-sensitive copying seals utilizing the principle of color development by reaction are well known.

Generally, such a pressure-sensitive copying sheet is a top paper (CB) obtained by coating a support with microcapsules containing a chromogen substance prepared by a method such as a phase separation method, an interfacial polymerization method, an in-situ method,
Lower paper (CF) coated with the other chromogenic substance that reacts with the chromogen on the support, and medium paper with the microcapsules and the chromogenic substance coated on different surfaces of the support ( CF
B) is used in combination as appropriate.

There is also a so-called single unit pressure-sensitive copying sheet in which the microcapsules and the chromogen substance are separately applied on the same surface of the support as a laminated or mixed layer, and the capsule layer is formed on the back surface of the single unit pressure-sensitive copying sheet. And a single pressure-sensitive copy sheet set in which the above lower paper and middle paper are appropriately combined.

Usually, these pressure-sensitive copy sheets are produced by applying a water-based paint to a support with a large-sized coating machine. As a special production method, capsules are made into ink and spot-printed with a printing machine. There is a way.

With spot printing of capsule ink, it is possible to print expensive capsule paint only on the required parts of the support, which is more efficient than the method of coating the entire surface of the support with a large-scale coating machine. Some varieties have very excellent economic characteristics. However, when a non-aqueous capsule ink is printed, the core substance is more easily extracted by the vehicle in the ink than when the aqueous capsule coating liquid is applied over the entire surface with a coating machine. Alternatively, when printing medium paper etc. with paper as a support because the capsule is easily destroyed by printing pressure, the chromogen substance on the capsule side passes through the support and the other chromogen on the back side It has a drawback that it causes a colored stain (hereinafter referred to as "short stain") when it reacts with a substance.

[Problems to be Solved by the Invention] The present invention has an object to provide a pressure-sensitive copying sheet free from short-circuit stains by printing a non-aqueous capsule ink on a support.

"Means for Solving the Problem" The present invention provides the other chromogen which develops a color by reacting with the chromogen substance on the back surface of a sheet provided with a receiving layer containing a chromogen substance on a support. In a pressure-sensitive copying sheet obtained by printing a non-aqueous microcapsule ink containing a body substance as a core substance, the support has an air permeability based on JIS P 8117 (hereinafter, simply referred to as "air permeability"). It is a pressure-sensitive copy recording sheet characterized by using a base paper for 90 seconds or more.

"Action" The sheet as the support used in the present invention is
The target is acidic paper, neutral paper, and synthetic paper obtained by making fibers such as natural pulp or synthetic pulp.
The present invention is characterized in that these base papers having an air permeability of 90 seconds or more are used. Incidentally, as a method for making the air permeability of the base paper 90 seconds or more, a size press of a binder is applied to the base paper, or a method of applying a barrier property by applying a binder, or the pulp is preliminarily beaten during papermaking. Alternatively, it may be a paper made and then finished into glassine paper. In addition, in the point that it is possible to effectively prevent the penetration of the ink when printing the microcapsule ink, a binder is size-pressed or applied to give a barrier property so that the air permeability becomes a value of 90 seconds or more. The set one is more preferable.

Thus, in the present invention, it is possible to obtain a pressure-sensitive copying sheet having an extremely high degree of whiteness, which completely prevents short-circuit stains using a support having an air permeability of 90 seconds or more.

The treatment with a binder for improving the air permeability of the base paper is usually performed during the paper making process or by a coating machine after the paper making, but after the chromogenic substance-containing coating liquid is provided on the base paper, It is also possible to use a coating machine or a printing machine on the back surface.

Examples of the binder used for this purpose include those that form a polymer film by a reaction such as evaporative drying of the medium or polymerization.

Specifically, a water-soluble binder or latex is used in an aqueous system, a resin is used in an organic solvent system, and a radiation curing compound is used in a solventless system.

As the water-soluble binder, gelatin, albumin,
Proteins such as casein, starches such as cereal starch, pregelatinized starch, oxidized starch, etherified starch, esterified starch, celluloses such as carboxymethyl cellulose and hydroxyethyl cellulose, saccharose such as agar, sodium alginate, and gum arabic. Water-soluble natural polymer compounds such as polyvinyl alcohol, polyvinylpyrrolidone, sodium polyacrylate, polyacrylamide, vinyl acetate-sodium maleic anhydride salt, vinyl acetate-ammonium maleic anhydride salt, styrene-ammonium maleic anhydride salt, etc. Examples thereof include water-soluble synthetic polymer compounds such as maleic acid copolymer salts and sodium salts of butadiene-methacrylic acid.

As the latex, styrene-butadiene latex, acrylonitrile-butadiene latex, acrylic ester latex, vinyl acetate latex,
Methyl methacrylate-butadiene latex and carboxy-modified (eg acrylic acid) latex thereof, and the like.

As resin, rosin (gum rosin, wood rosin,
Tall oil rosin), Cerax, Copal, Dalman,
Gilsonite, natural resin such as zein, cured rosin, ester gum and other rosin esters, maleic acid resin, fumaric acid resin, dimerized rosin, polymerized rosin, rosin-modified phenolic resin, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, Semi-synthetic resin such as ethyl hydroxyethyl cellulose, carboxymethyl cellulose, cellulose acetate propionate, cellulose acetate butyrate, nitrile cellulose, phenol resin, xylene resin, urea resin, melamine resin, ketone resin, chroman indene resin, petroleum resin, terpene Resin, deoxidized rubber, chlorinated rubber, algide resin, polyamide resin, acrylic resin, polyvinyl chloride, vinyl chloride / vinyl acetate copolymer, polyvinyl acetate Ethylene - maleic anhydride copolymer, styrene - maleic anhydride copolymer, methyl vinyl ether - maleic anhydride copolymer, isobutylene -
Synthetic resins such as maleic anhydride copolymer, polyvinyl alcohol, modified polyvinyl alcohol, polyvinyl butyral (butyral resin), polyvinyl pyrrolidone, chlorinated polypropylene styrene resin, epoxy resin and polyurethane.

Examples of the radiation-curable compound include one or more vinyl or vinylidene groups, preferably a compound unique to a plurality of them. Examples thereof include a reaction product of an alcohol or the like with an unsaturated carboxylic acid, a reaction product of a hydroxyl group-containing acrylate or methacrylate with a polyisocyanate, and the like.

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, a reaction product of an epoxy resin and acrylic acid, a reaction product of methacrylic acid, pentaerythritol and acrylic acid, a condensation product of maleic acid, diethylene glycol and acrylic acid, methyl methacrylate,
Butyl methacrylate, styrene, etc.

As the organic solvent used to dissolve the resin, benzene, toluene, xylene, cyclohexane, hexane, ligroin, methyl isobutyl ketone, methyl acetate, ethyl acetate, butyl acetate, methyl cellosolve, ethyl cellosolve, butyl cellosolve, diethylene glycol monobutyl ether, diethylene glycol monobutyl ether acetate. , Methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol,
n-hexonol, cyclohexanol, etc. are mentioned.

If necessary, pigments, microcapsules, dispersants, surfactants, defoamers, preservatives, fluorescent dyes, antioxidants, crosslinking agents, photopolymerization initiators, sensitizers, etc. are added to the binder. To be done.

The amount of binder used is usually 100 parts by weight of fiber.
0.2 to 50 parts by weight, particularly preferably 1 to 20 parts by weight.

When the binder is applied with a coating machine, various known coating methods such as an air knife coater, roll coater, blade coater, size press coater, curtain coater, bill blade coater and short dwell coater are used.

Examples of the combination of chromogenic substances used in the present invention include a combination of an electron-donating color former and an electron-accepting developer, or a combination of a metal salt and a ligand compound. The chromogenic substance usually contained in the capsule ink is an electron-donating color former or a ligand compound, and the other chromogenic substance used in the receiving layer is an electron-accepting developer or a metal salt. . Examples of the electron-donating color former include the following substances known in the field of pressure-sensitive copying paper.

6-dimethylaminophthalide, 3- (p-dimethylaminophenyl) -3- (1,2-dimethylindole-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-dimethylaminobenzhydryl benzyl ether, N-halophenyl-leuco auramine, N-2,
Diphenylmethane dyes such as 4,5, -trichlorophenyl leuco auramine, benzoyl leuco methylene blue,
Thiazine dyes such as p-nitrobenzoyl leuco methylene blue, 3-methyl-spiro-dinaphthopyran, 3-
Spiro dyes such as phenyl-spiro-dinaphthopyran and 3-propyl-spiro-dibenzopyran, rhodamine-
L-lactam dyes such as B-anilinolactam, rhodamine (p-nitroanilino) lactam 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-dibenzylaminofluorane, 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-6-methyl-7phenylaminofluorane, 3-diethylamino-6-methyl-
Fluorane dyes such as 7-xylidinofluorane and mixtures thereof.

Examples of the electron-accepting color developing agent include the following substances known in the field of pressure-sensitive copying paper.

Acid clay, activated clay, attapulgite, zeolite, clays such as bentonite, phenolic resins, polyvalent metal salts of various aromatic carboxylic acids as described in JP-B-51-25174, JP-A-54-106316 Zinc salts of 2,2 ′ bisphenol sulfone compounds and the like and mixtures thereof.

Examples of the combination of the metal salt and the ligand compound include the following combinations of substances known in the field of pressure-sensitive copying paper.

Nickel stearate and N, N'-di-benzyl-di-
Thio-oxamide, nickel laurate and α-benzyl glyoxime, tricaprylmethyl ammonium vanadate and dodecyl amine 8-hydroxyquinoline sulfonate, benzyl lauryl dimethyl ammonium molybdate and lauryl protocatechuate, titanium stearate and lauryl gallate, Iron naphthenate and benzyl gallate, polyferrophenylmethylsiloxane and methylenebis (8-oxyquinoline), copper palmitate and N, N'-
Bis-2-octanoyloxyethyldiethyldithiooxamide, cobalt laurylate and di-o-tolylguanidine, hinokitiol and polyvanadophenylmethylsiloxane, organic iron phosphates and gallic acid described in JP-A-58-38191 Combinations such as lauryl acid and mixtures thereof. When an aromatic polyvalent metal salt, which is an electron-accepting color developer, is used as the chromogenic substance of the receiving layer, the effect of the present invention on the prevention of short-circuit stain is remarkable.

In the case of microencapsulating the chromogenic substance as described above, the chromogenic substance is usually encapsulated in a state of being dissolved in oil. As such an oil, for example, it is known in the field of pressure-sensitive copying paper. The following substances are exemplified.

Vegetable oils such as cottonseed oil, mineral oils such as kerosene, paraffin, naphthene oil and chlorinated paraffin, aromatic carbonization such as alkylated biphenyl, alkylated terphenyl, alkylated naphthalene, diarylethane, triarylmethane and diphenylalkane. Hydrogen, oleyl alcohol, tridecyl alcohol, benzyl alcohol, 1
-Alcohols such as phenylethyl alcohol and glycerin, organic acids such as oleic acid, dimethyl phthalate, diethyl phthalate, di-n-butyl phthalate,
Dioctyl phthalate, diethyl adipate, diethyl butyl adipate, esters such as dioctyl adipate, tricresyl phosphate, tributyl phosphate, tributyl phosphite, organic phosphorus compounds such as tributyl phosphine oxide, phenyl cellosolve,
Ethers such as benzyl carbitol, polypropylene glycol, propylene glycol monophenyl ether, amides such as N, N-dimethyllauramide, N, N-dimethylstearamide, N, N-dihexyloctylamide, diisobutyl ketone, methylhexyl Ketones such as ketones, alkylene carbonates such as ethylene carbonate and propylene carbonate, and mixtures thereof.

As the encapsulation method, conventionally known coacervation method, interfacial polymerization method, in-situ method and the like can be appropriately selected and used, but it is preferable to use a synthetic resin as a wall film material,
Among them, the use of a melamine formaldehyde resin capsule as described in Japanese Patent Application No. 59-23698 is particularly preferable because a pressure-sensitive copying sheet having more excellent performance can be obtained.

It should be noted that these microcapsules may contain an antioxidant, an ultraviolet absorber, etc., if necessary.

The thus obtained microcapsule dispersion containing the chromogenic substance, after undergoing a concentration step such as the prepared dispersion or filtration, air drying, surface drying, fluidized drying, air stream drying, spray drying, vacuum drying, Most of the dispersion medium is removed by a means such as freeze-drying, infrared-ray drying, high-frequency drying, ultrasonic drying, and fine pulverization drying to obtain a powder capsule. Then, it is dispersed in a non-aqueous medium to prepare a microcapsule ink.

Incidentally, as described in JP-A-53-135718, a method of mixing an aqueous capsule dispersion and a non-aqueous medium, and then removing the aqueous medium under reduced pressure or filtering the capsule dispersion, then a non-aqueous The capsule ink can be prepared also by a method of substituting with a medium.

In addition, resins, capsule protectors, white pigments, desensitizing components, UV absorbers, antioxidants, fluorescent paints, plasticizers, surfactants, chromogenic substances, etc. are added to the ink medium as needed. can do.

As the resin, the above-mentioned resins are used as the binder, and these are appropriately selected and used according to the type of ink medium.

Examples of the capsule protector include cellulose powder, starch particles, microspheres, glass beads, synthetic resin powder and the like.

As the desensitizer component, in the case of a leuco recording material,
Various amino compounds may be mentioned. In the case of iron-chelate recording materials, organic phosphoric acid compounds and compounds having an aminocarboxylic acid group as described in JP-A-59-38089 are used.

The white pigment, aluminum, zinc, magnesium, calcium, oxides such as titanium, hydroxide compounds, carbonates, sulfates, halogen compounds and acid clay, attapulgite, zeolite, bentonite, kaolin, clay such as calcined kaolin, Examples include organic pigments such as melamine resins and urea resins.

Examples of the ink medium used in the present invention include various media known in the printing industry.

In the case of Fluxo type and gravure type ink, benzene,
Toluene, xylene, cyclohexane, hexane, ligroin, methyl isobutyl ketone, methyl acetate, ethyl acetate, butyl acetate, methyl cellosolve, ethyl cellosolve, methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol and the like are preferable, and particularly methanol, A low boiling alcohol such as ethanol is most preferably used, and a small amount of n-hexanol, cyclohexanol or water is added to control the drying property of the ink, or methyl acetate, ethyl acetate, butyl acetate, methyl cellosolve, ethyl is used. Cellosolve and the like are added.

In the case of a flexographic agent or a clavia type ink, a resin is added as a binder, and the resin as described above is used as the resin. Among them, polyvinyl acetate, vinyl chloride / vinyl acetate copolymer, ethylene-maleic anhydride copolymer, styrene-maleic anhydride copolymer, methyl vinyl ether-maleic anhydride copolymer, isobutylene-maleic anhydride copolymer , Modified polyvinyl alcohol, polyvinyl butyral, polyvinyl pyrrolidone,
Ethyl cellulose, nitrocellulose, hydroxypropyl cellulose, cellulose acetate propionate, cellulose acetate butyrate and the like are preferable.

Waxes are mainly used as a medium of the hot melt type ink. The waxes include beeswax, whale wax, animal waxes such as lanolin, candelilla wax, carnauba wax, wood wax, rice wax,
Plant wax such as sugar cane wax, monta wax,
Mineral wax such as ozokerite, lignite wax, petroleum wax such as paraffin wax, microcrystalline wax, modified wax such as montan wax derivative, paraffin wax derivative, microcrystalline wax derivative, hydrogenated wax such as castor wax and opal wax , Low molecular weight polyethylene and its derivatives, synthetic waxes such as acra wax, distearyl ketone, caproic acid amide, capric acid amide, pelargonic acid amide, capric acid amide, lauric acid amide, tridecyl acid amide, myristic acid amide, stearic acid amide , Behenic acid amide, ethylene bisstearic acid amide, caprolein acid amide, oleic acid amide, linoleic acid amide, ricinoleic acid amide , Fatty acid amide waxes such as linolenic acid amide, fatty acid waxes such as behenic acid, alcohol waxes such as stearyl alcohol,
A phosphate ester wax such as distearyl phosphate ester is used alone or in combination.

Among them, oxide mineral waxes such as montan wax, ethylene bis-stearic acid amide, stearic acid amide, amide waxes such as behenic acid amide, fatty acid wax, phosphate wax and mixtures thereof, needle hardness of 0.1 to 30, Those having a melting point of 50 ° C to 160 ° C and a melting range of less than 20 ° C are preferably used.

In addition to the above waxes, it is also possible to use an aromatic hydrocarbon compound having a melting point in the range of 40 ° C to 200 ° C, in which case a resin soluble in the molten aromatic hydrocarbon compound is used in combination. Is desirable.

A good system can also be obtained by using an aromatic hydrocarbon compound and waxes in combination, but in that case, it is desirable to use a resin in the mixed system.

Specific examples of the aromatic hydrocarbon compound include 2,6-
Diisopropylnaphthalene, 1,4.5-trimethylnaphthalene, 2,3,5-trimethyl-naphthalene, 2,3-dimethylnaphthalene, 1,3,6,8-tetramethylnaphthalene, 1,2-
Di-o-tolylethane, bis (2,4,5-trimethylphenyl) methane, 1,18-diphenyl-octadecane, 1,3
-Ta-phenyl, 1,2-di-p-tolylethane, diphenyl-p-tolylmethane, 1,2-dibenzylbenzene,
3,4-diphenylhexane, 1,2-bis (2,3-dimethylphenyl) ethane, 4,4'-isopropylidene diphenol, bisresorcinol ethylene ether, 4-tertiary
Shari-butyl-phenyl salicylate, 2,2-bis (4-acetoxyphenyl) propane, bis (4-acetoxyphenyl) sulfone, terephthalic acid dimethyl ether, terephthalic acid di-chlorophenyl ester, terephthalic acid distearylamide, malonic acid ethyl ester , 4-methoxyanilide, benzyl mandelic acid, benzoic acid phenyl ester, benzoic acid-2-naphthyl ester, 2-hydroxy-3-octylcarbamoylnaphthalene, 4-hydroxybenzoic acid benzyl ester, p-
Examples thereof include benzyl benzyloxybenzoate, 1,4-bispropionyloxybenzene, and 1,1-dibenzoylmethane.

Examples of the resin include the resins described above, but among them, cured rosin, ester gum, ethyl cellulose, phenol resin, rosin-modified phenol resin, urea / melamine resin, chlorinated rubber, reduced rubber, maleic acid resin petroleum resin,
A terpene resin or the like is preferably used.

Further, as the medium of the electron beam or ultraviolet curable ink, the above-mentioned radiation curable compound is used as a binder.

When cured by ultraviolet rays, it is preferable to add a photopolymerization initiator to the medium, for example, an aromatic ketone,
A photopolymerization initiator such as a quinone compound, an ether compound or a nitro compound is used.

Specifically, start photopolymerization of benzoquinone, phenanthrenequinone, naphthoquinone, diisopropylphenanthrenequinone, benzoin butyl ether, benzoin, furoin butyl ether, Michler's ketone, Michler's thioketone, fluorenone, trinitrofluorenone, β-benzoylaminonaphthalene, etc. An agent is illustrated.

Oils are used as a medium for the oxidation polymerization type (letterpress type) ink, and if necessary, a solvent, a wax, a drier,
Thickeners, gelling agents, thixotropic agents, etc. are added.

As the oil, vegetable oil (dry oil such as linseed oil and sunflower oil, semi-drying oil such as soybean oil, unsaturated oil such as castor oil), processed oil (dehydrated castor oil, polymerized oil, maleated oil,
Vinylated oils, urethane oils), mineral oils (machine oils, spindle oils) and the like.

Examples of the solvent include high boiling point petroleum solvent (ink oil), diethylene glycol monobutyl ether, diethylene glycol monobutyl ether acetate and the like.

The microcapsule ink containing the chromogenic substance thus prepared is applied on the base paper according to various printing methods such as letterpress, intaglio (gravure), flat plate (offset) and screen.

The coating amount of the capsule ink is appropriately adjusted according to the type of the prepared ink, and is not particularly limited, but generally 0.3 to 10 g / m ² or so, preferably 1 to 5
It is adjusted within the range of g / m ² . By the way, when it is 0.3 g / m ² or less, sufficient color cannot be obtained when copied, and when it is 10 g / m ² or more, there is no problem in terms of effect, but it is not necessary in terms of economy.

The chromogenic substance forming the receptive layer is pulverized by a ball mill, attritor, sand mill or the like, if necessary, and then a commonly used white pigment, a binder, and if necessary, a dispersant, an oil capsule. , A colored dye, a fluorescent whitening agent, an ultraviolet absorber, an antioxidant, an antifoaming agent, and various other auxiliaries are used in combination to prepare a coating liquid.

The amount of the chromogen substance to be incorporated in the receptor layer is not particularly limited, but from the viewpoint of color development and economy, the solid content of the coating material is used.
1 to 50 parts by weight, preferably 3 to 3 parts by weight per 100 parts by weight
5 parts by weight.

As the white pigment, the same types as those exemplified as the substances added in the coating amount of the capsule ink are appropriately selected and used.

The receptive layer-forming coating liquid thus prepared is applied to the paper using various coating machines as described in the binder coating.

The coating amount of the receiving layer-forming coating liquid is appropriately adjusted according to the type of the coating liquid prepared, and is not particularly limited, but is generally about ² to 15 g / m ² , and preferably 3 to 7 g
It is adjusted in the range of about / m ² . By the way, when it is ² g / m ² or less, sufficient color development cannot be obtained when copying, and when it is 15 g / m ² or more, it is not necessary in terms of effect.

"Examples" Examples and comparative examples will be given below in order to further clarify the effect of the present invention, but the present invention is not limited to these examples. The parts and% in the examples represent parts by weight and% by weight, unless otherwise specified.

Making of base paper 80 parts of LPKP and 20 parts of NBKP are beaten, 1.5 parts of rosin, 3.0 parts of sulfuric acid band, and 6 parts of talc are added and a base paper with air permeability of 15 seconds and basis weight of 40 g / m ² is made with a Fourdrinier did.

Base paper for Example 1 Using the above papermaking base paper, a 5% polyvinyl alcohol aqueous solution was applied with an air knife coater to obtain a base paper for pressure-sensitive copying paper having air permeability as shown in Table 1. .

Base paper for Example 2 Using the above papermaking base paper, a 25% aqueous solution of oxidized starch was size-pressed to obtain a base paper for pressure-sensitive copying paper having air permeability as shown in Table 1.

Base paper for Comparative Example 1 Paper made in the same manner as in Example with air permeability of 35 seconds and basis weight of 40 g / m ²
The base paper that had not been treated with the barrier agent was used as the base paper for pressure-sensitive copying paper.

Base paper for Comparative Example 2 Paper made in the same manner as in Example with air permeability of 15 seconds and basis weight of 40 g / m ²
The base paper that had not been treated with the barrier agent was used as the base paper for reduced-pressure copying paper.

(Preparation of the lower paper) 65 parts of light calcium carbonate, 20 parts of zinc oxide, a blended part (blending ratio) of 3,5-di (α-methylbenzyl) salicylic acid zinc salt and α-methylstyrene / styrene copolymer 80/2
0) 15 parts, polyvinyl alcohol aqueous solution 5 parts (solid content)
And a developer liquid prepared by adding 20 parts (solid content) of a carboxy-modified styrene-butadiene copolymer latex to a pulverized liquid obtained by pulverizing 300 parts of water with a ball mill for 24 hours, and Examples 1 to 7 The dry weight of each base paper for
A lower sheet was obtained by smearing with an air knife coater so as to give 5 g / m ² .

(Preparation of Capsule Ink for Pressure Sensitive Copy Paper) 8 parts of crystal violet lactone was dissolved in 100 parts of alkyldiphenylethane (trade name: Hisol SAS-296, manufactured by Nippon Petrochemical Co., Ltd.) by heating to obtain an internal phase oil. Ethylene
To 200 parts of a 3.0 aqueous solution of maleic anhydride copolymer (trade name EMA-31, manufactured by Monsanto), 20% caustic soda aqueous solution was added to emulsify the internal phase oil into a solution having a pH of 6.0, and then the system was changed to The temperature was raised to 55 ° C.

Separately, 45 parts of 37% aqueous formaldehyde solution contained 15 parts of melamine.
Parts were added and reacted at 60 ° C. for 15 minutes to prepare an aqueous prepolymer solution. This prepolymer aqueous solution was added dropwise to the above emulsion, and after stirring, the temperature was raised to 80 ° C, the temperature was maintained for 1 hour, the pH of 0.2N-hydrochloric acid was lowered to 3.5, the temperature was kept for 3 hours, and then allowed to cool. Thus, a capsule dispersion liquid having an average particle diameter of 2.6μ was obtained.

Then, this dispersion liquid was filtered and further washed with ethanol, and then the capsule was redispersed in a mixed solvent of 330 parts of ethanol and 165 parts of n-propanol, and 25 parts of light calcium carbonate, ethyl cellulose No. 14 (hercules No. 14). 80 parts by weight) was added to obtain a flexo type capsule ink.

(Creation of medium paper) A business form printing machine prints the above-mentioned capsule ink on the back side of each lower paper at a speed of 80 m / min, and a spot of 10 cm x 10 cm square where the ink amount is 2.5 g / m ^2. I got a print.

The degree of short-circuit stain was as shown in Table 1 as a result of the visual judgment of the short-circuit stain due to the printing of the pressure-sensitive copying paper thus obtained.

(Effect) As apparent from the examples, the pressure-sensitive copying paper obtained in the present invention was free from short-circuit stains.

Claims (1)

(57) [Claims] 1. A core material containing, on the back surface of a sheet having a support provided with a chromogenic substance, another chromogenic substance which reacts with the chromogenic substance to develop a color. In a pressure-sensitive copying sheet obtained by printing a non-aqueous microcapsule ink, a base paper having an air permeability of 90 seconds or more according to JIS P 8117 is used as the support, A pressure-sensitive recording sheet characterized by not passing through the body