JPH01264888A - Pressure sensitive recording note - Google Patents

Abstract

PURPOSE:To prevent a short stain wherein a color primary substance on a capsule side is reacted on a developer on a rear face by contact, by taking original paper having specific air permeability as a base material of a pressure sensitive copying sheet. CONSTITUTION:A pressure sensitive copying sheet can be obtained by printing nonaqueous microcapsule ink containing a color primary substance coloring by reaction on another color primary substance as a core substance on a back surface of a sheet prepared by establishing an accepting layer containing said another color primary substance to a base material. At that time, original paper of 40sec or over in air permeability based on JIS-P-8117 is used as the base material. Further, in order to prevent effectively permeation of ink when microcapsule ink is printed, the base material is preferably so established that the gas permeability becomes to have a value of 40sec or over by given barrier property by size pressing or coating binder, and as binder to be used, a binder wherein a high molecular film is formed by reaction of evaporation drying or polymerization, etc., of a medium is exemplified.

Description

Detailed Description of the Invention "Industrial Application Field" The present invention relates to a pressure-sensitive copying sheet, and particularly relates to a pressure-sensitive copying sheet, and more particularly, to a pressure-sensitive copying sheet provided with a layer containing a chromogen substance, and a method for printing a capsule ink on the back side of the sheet. This invention relates to improvements in pressure copying sheets.

"Prior art" Combination of electron-donating color formers such as crystal bioleft lactone and benzoyl leucomethylene blue and electron-accepting color developers such as activated clay, phenol formaldehyde SL, and polyvalent metal salts of aromatic carboxylic acids. , or the reaction of various chromogen substances, such as combinations of nickel carboxylic acid salts and N,N'-dibenzyludithiooxamide, organic iron phosphate salts, metal salts such as lauryl gallate, and ligand compounds, etc. Pressure-sensitive copying sheets that utilize the principle of color development are well known.

In general, such pressure-sensitive copying sheets are paper sheets (C
B) Top paper (CF) in which the support is coated with another chromogen substance that reacts with the above chromogen to develop color; the above microcapsules and the chromogen substance are coated on separate sides of the support It is put into practical use by appropriately combining the medium paper (CFB).

There is also a so-called single pressure-sensitive copying sheet in which the above-mentioned microcapsules and chromogen material are separately coated as a laminated or mixed layer on the same side of a support, and a capsule layer is further coated on the back side of the single pressure-sensitive copying sheet. There is also a single pressure-sensitive copying sheet set in which the above-mentioned bottom paper and middle paper are appropriately combined.

Normally, these pressure-sensitive copying sheets are manufactured by applying water-based paint to a support using a large coating machine, but a special manufacturing method involves converting capsules into ink and spot printing using a printing machine. There is a way.

Capsule ink spot printing is more flexible than the method of applying water-based paint to the entire surface of the support using a large coating machine, as it allows expensive capsule paint to be printed only on the necessary areas of the support. Some varieties exhibit excellent economic characteristics. However, when printing with a non-aqueous capsule ink, the core substance is more likely to be extracted by the vehicle in the ink than when an aqueous capsule coating liquid is applied over the entire surface using a coating machine. Alternatively, when creating inner paper etc. using paper as a support, the capsule is easily destroyed by printing pressure, and the chromogen substance on the capsule side passes through the support and is absorbed by the other chromogen on the back side. Color stains that develop due to contact reaction with body substances (
It has the disadvantage of causing short-circuit stains (hereinafter referred to as "short-circuit stains").

- "Problems to be Solved by the Invention" The object of the present invention is to provide a pressure-sensitive copying sheet free from short stains by printing a non-aqueous capsule ink on a support.

"Means for Solving the Problems" The present invention provides a method in which another chromogen that reacts with the chromogen substance to form a color is added to the back side of a sheet in which a support layer is provided with a receptor layer containing a chromogen substance. In a pressure-sensitive copying sheet obtained by printing a non-aqueous microcapsule ink containing body material as a core material, JIS P 811 is used as the support.
Air permeability based on 7 (hereinafter simply referred to as "air permeability")
This is a pressure-sensitive copying recording sheet characterized by using a base paper with a pressure resistance of 40 seconds or more.

"Function" The sheet as a support used in the present invention is intended for acidic paper, neutral paper, and synthetic paper obtained by paper-making fibers such as natural bulb or synthetic bulb. These base papers are characterized in that they have an air permeability of 40 seconds or more. Incidentally, methods for increasing the air permeability of the base paper to 40 seconds or more include a method of size-pressing or applying a binder to the base paper to impart barrier properties, or a method of heavily beating the pulp before making the base paper. The paper may be made into glassine paper after being made. In addition, in terms of effectively preventing ink penetration when printing with microcapsule ink, a binder can be size-pressed or applied to provide barrier properties and the air permeability should be 40 seconds or more. The one set is more preferable.

Therefore, in the present invention, it is extremely important that the air permeability is 40 seconds or more, and if a base paper with less than 40 seconds is used,
Short stains are noticeable and it is impossible to obtain a pressure-sensitive copying sheet of practical level. If the air permeability value is 40 seconds or more, a practical pressure-sensitive copying sheet can be obtained, if a support is used for 60 seconds or more, most short-circuit stains can be prevented, and if it is 80 seconds or more By using this support, it is possible to obtain a pressure-sensitive copying sheet with extremely high whiteness that completely prevents short-circuit stains.

Incidentally, treatment with a binder to improve the air permeability of base paper is usually carried out during the papermaking process or by a coating machine after papermaking, but treatment with a binder is performed after applying a coating liquid containing a color substance to the base paper. It can also be applied to the back surface using a coating machine, a printing machine, etc.

Examples of the binder used here include those that form a polymer film through a reaction such as evaporation drying or polymerization of a medium.

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 solvent-free system.

Examples of water-soluble binders include proteins such as gelatin, albumin, and casein, and starches* such as grain starch, pregelatinized starch, oxidized starch, etherified starch, and esterified starch.
, celluloses such as carboxymethyl cellulose and hydroxyethyl cellulose, agar, sodium alginate,
Water-soluble natural polymer compounds such as saccharoses such as gum arabic, polyvinyl alcohol, polyvinylpyrrolidone, sodium polyacrylate, polyacrylamide,
Maleic acid copolymer salts such as sodium salt of vinyl acetate-maleic anhydride, ammonium salt of vinyl acetate-maleic anhydride, ammonium salt of styrene-maleic anhydride,
Examples include water-soluble synthetic polymer compounds such as sodium salt of butadiene-methacrylic acid.

Examples of the latex include styrene-butadiene latex, acrylonitrile-butadiene latex, acrylic acid ester latex, vinyl acetate latex, methyl methacrylate-butadiene latex, and carboxy-modified (for example, acrylic acid) latex thereof.

Examples of resins include rosin (gum rosin, wood rosin, tall oil rosin), natural resins such as serafucus, copal, dalman, giltnite, and zein, hardened rosin, ester gum and other rosin esters, maleic acid resin,
Fumaric acid resin, trimerized rosin, polymerized rosin, rosin-modified phenolic resin, methylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, ethylhydroxyethylcellulose, carboxymethylcellulose, cellulose acetate propionate, cellulose acetate butyrate, nitrocellulose, etc. Synthetic resins, phenolic resins, xylene resins, urea resins, melamine resins, ketone resins, coumaron/indene resins, petroleum resins, terpene resins, tethered rubber, chlorinated rubber, algide resins, polyamide resins, acrylic resins,
Polyvinyl chloride, vinyl chloride/vinyl acetate copolymer, polyvinyl acetate, ethylene-maleic anhydride copolymer, styrene-maleic anhydride copolymer, methyl vinyl ether-maleic anhydride copolymer, isobutylene-maleic anhydride Synthetic resins such as copolymers, polyvinyl alcohol, modified polyvinyl alcohol, polyvinyl butyral (butyral resin), polyvinylpyrrolidone, chlorinated polypropylene styrene resin, epoxy resin, and polyurethane.

Examples of radiation-curable compounds include compounds having one or more vinyl or vinylidene groups, preferably a plurality of vinyl or vinylidene groups,
For example, acryloyl group, methacryloyl group, allyl group,
Examples include reactants of unsaturated carboxylic acids with polyols, polyamines or amino alcohols having unsaturated polyesters, vinyloxy or acrylamide groups, and reactants of polyisocyanates with acrylates or methacrylates having hydroxyl groups.

Typical 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 methacrylic acid, pentaerythster and acrylic acid, condensation product of maleic acid, diethylene glycol and acrylic acid, methyl methacrylate,
Examples include butyl methacrylate and styrene.

Organic solvents used to dissolve the resin include 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 motsubutyl ether acetate, methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-7' tanol, n-
Examples include hexonol, cyclohexanol, and the like.

In addition, pigments, microcapsules, dispersants, surfactants, antifoaming agents, preservatives, fluorescent dyes, antioxidants, crosslinking agents, photoinitiators, sensitizers, etc. may be added to the binder as necessary. be done.

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

Further, when applying the binder 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, short dwell coater, etc. are used.

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

6-dimethylaminophthalide, 3-(p-dimethylaminophenyl')-3-(1,2-dimethylindol-3-yl)phthalide, 3,3-bis(l,2-dimethylindol-3-yl) )-5-dimethylaminophthalide, triallylmethane dyes such as 3,3-bis(9-ethylcarbazol-3-yl)-6-dimethylaminophthalide, 4゜4'-bis-dimethylaminobenzyl Diphenylmethane dyes such as drill benzyl ether, N-halophenyl-leuco auramine, N-2,4,5,-trichlorophenyl leuco auramine, thiazine dyes such as benzoyl leucomethylene blue, p-nitrobenzoyl leuco methylene blue, 3- Spiro dyes such as methyl-spiro-dinaphthopyran, 3-phenyl-spiro-dinaphthopyran, 3-propyl-spiro-dibenzobilane, rhodamine-B-anilinolactam, rhodamine (p-nitroanilino)lactam, rhodamine (0-chloroanilino) Lactam dyes such as lactam, 3-dimethylamino-7-methylfluoran, 3-diethylamino-6-methyl-7-chlorofluoran, 3-(N-ethyl-p-)luidino)-7-methylfluoran , 3-
diethylamino-7-N-methylaminofluorane, 3
-diethylamino-7-dibenzylaminofluorane,
3-(N-ethyl-p-)luidino)-6-methyl=7
-phenylaminofluorane, 3-diethylamino-6
-Methyl-7-phenylaminofluorane, 3-(N-
cyclohexyl-N-methylamino)-6-methyl-7
-Fluoran dyes such as phenylaminofluorane, 3-piperidino-6-methyl-7phenylaminofluorane, 3-diethylamino-6-methyl-7-xylidinofluorane, and mixtures thereof.

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

Clays such as acid clay, activated clay, akbarthite, zeolite, and bentonite, phenolic resins, polyvalent metal salts of various aromatic carboxylic acids as described in Japanese Patent Publication No. 51-25174, and polyvalent metal salts of various aromatic carboxylic acids as described in JP-A-54-106316. Like 2
．． Zinc salts of 2'bisulfonol sulfone compounds, etc., and mixtures thereof.

Examples of combinations of metal salts and ligand compounds include the following combinations of substances known in the field of pressure-sensitive copying paper.

Nickel stearate and N,N'-dibenzyludithioxamide, nickel laurate and α-benzylglyoxime, tricaprylmethylammonium vanadate and dodecylamine 8-hydroxyquinolinesulfonate, benzyllauryldimethylammonium 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 laurate and di-o-1-lylguanidine, hinokitiol and polyvanadophenylmethylsiloxane, organic phosphoric acid described in JP-A-58-38191 Combinations of iron and lauryl gallate, etc., and mixtures thereof.

When an aromatic polyvalent metal salt, which is an electron-accepting color developer, is used as the chromogen substance of the receiving layer, the effect of the present invention on preventing short staining is particularly remarkable.

When microencapsulating chromogen substances such as those mentioned above,
The chromogen substance is usually encapsulated in a state dissolved in oil, and examples of such oil include the following substances known in the field of pressure-sensitive copying paper.

Aromatic carbonization of vegetable oils such as cottonseed oil, mineral oils such as kerosene, paraffin, naphthenic oil, and chlorinated paraffin, alkylated biphenyls, alkylated terphenyls, alkylated naphthalenes, diarylethanes, triarylmethanes, diphenylalkanes, etc. Hydrogens, oleyl alcohol, tridecyl alcohol, benzyl alcohol, 1-
Alcohols such as phenylethyl alcohol and glycerin, organic acids such as oleic acid, esters such as dimethyl phthalate, diethyl phthalate, di-n-butyl phthalate, dioctyl phthalate, diethyl adipate, diebutyl adipate, dioctyl adipate,
tricresyl phosphate, tributyl phosphate,
Organic phosphorus compounds such as tributyl phosphite and tributyl phosphine oxide, ethers such as phenyl cellosolve, pendyl carbitol, polypropylene glycol and propylene glycol monophenyl ether, N, N-dimethyl lauramide, N.

Amides such as N-dimethylstearamide and N,N-dihexyl octylamide, ketones such as diisobutyl ketone and methylhexyl ketone, alkylene carbonates such as ethylene carbonate and propylene carbonate, and mixtures thereof.

As the encapsulation method, conventionally known coacervation method, interfacial polymerization method, 1n-situ method, etc. can be selected and used as appropriate, but it is preferable to use synthetic resin as the wall material. When using a melamine formaldehyde resin capsule as described in No. 59-23698,
This is particularly preferred since a pressure-sensitive copying sheet with better performance can be obtained.

Note that these microcapsules can also contain antioxidants, ultraviolet absorbers, etc., if necessary.

The thus obtained microcapsule dispersion containing the chromogen substance is subjected to the prepared dispersion or a concentration process such as filtration, followed by air drying, surface drying, fluidized drying, flash drying, spray drying, and vacuum drying. Most of the dispersion medium is removed by means such as freeze drying, infrared drying, high frequency drying, ultrasonic drying, pulverization drying, etc. to obtain powder capsules. Then, it is dispersed in a non-aqueous medium to prepare a microcapsule ink.

In addition, as described in JP-A No. 53-135718, after mixing an aqueous capsule dispersion and a non-aqueous medium, the aqueous medium is removed under reduced pressure, or after filtering the capsule dispersion, a non-aqueous medium is mixed. Capsule ink can also be prepared by a method such as replacing with a medium.

Furthermore, resins, capsule protectants, white pigments, desensitizing ingredients, ultraviolet absorbers, antioxidants, fluorescent paints, plasticizers, surfactants, chromogen substances, etc. are added to the ink medium as necessary. can do.

As the resin, the resin described above as a binder is used, and these are appropriately selected and used depending on the type of ink medium.

Capsule protectants include cellulose powder, starch particles,
Examples include microspheres, glass beads, and synthetic resin powder.

Desensitizer components include various amino compounds in the case of leuco recording materials, and organic phosphoric acids as described in JP-A-59-38089 in the case of iron-chelate recording materials. A type compound, a compound having an aminocarboxylic acid group, etc. are used.

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

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

For flexographic and gravure inks, benzene,
Toluene, xylene, cyclohexane, hexane, ligroin, methyl isobutyl ketone, methyl acetate, ethyl acetate, butyl acetate, methyl cellosolve butyl cellosolve, methanol, ethanol, n-propyl alcohol,
Isopropyl alcohol, n-butanol, etc. are preferred, and low-boiling alcohols such as methanol and ethanol are most preferably used, to which a small amount of n-hexanol, cyclohexanol, or water may be added to control the drying properties of the ink. In addition, methyl acetate, ethyl acetate, butyl acetate, methyl cellosolve, ethyl cellosolve, etc. are added.

In the case of flexo type and clavier type inks, a resin is added as a binder, and the resin mentioned 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 Preferred are polyvinyl alcohol, modified polyvinyl alcohol, polyvinyl butyral, polyvinylpyrrolidone, ethyl cellulose, nitrocellulose, hydroxypropyl cellulose, cellulose acetate propionate, cellulose acetate butyrate, and the like.

Waxes are mainly used as the medium for true melt ink. These waxes include animal waxes such as beeswax, spermaceti wax, and lanolin, vegetable waxes such as candelilla wax, carnauba wax, wood wax, rice wax, and sugarcane wax, and mineral waxes such as motan wax, osikerite, and lignite wax. system wax,
Petroleum waxes such as paraffin wax and microcrystalline wax, modified waxes such as monk wax derivatives, paraffin wax derivatives, and microcrystalline wax derivatives, hydrogenated waxes such as castor wax and opal wax, low molecular weight polyethylene and its derivatives, and acra wax. , synthetic waxes such as distearyl ketone, caproic acid amide, capric acid amide, pelargonic acid amide, capric acid amide, lauric acid amide, tridecylic acid amide, myristic acid amide, stearic acid amide, behenic acid amide, ethylene bisstearic acid amide , fatty acid amide waxes such as caproleic acid amide, oleic acid amide, linoleic acid amide, ricinoleic acid amide, linoleic acid amide, fatty acid based waxes such as behenic acid, alcohol based waxes such as stearyl alcohol, distearyl phosphate esters, etc. Phosphate ester waxes and the like can be used alone or in combination.

Among them, oxidized mineral wax such as montan wax, amide wax such as ethylene bisstearamide, stearamide, behenic acid amide, fatty acid wax, phosphate ester wax, and mixtures thereof, with a needle penetration of 0.1 to 30 Those having hardness, a melting point of 50°C to 160°C, and a solubility range of less than 20°C are preferably used.

In addition to the waxes mentioned above, aromatic hydrocarbon compounds having a melting point in the range of 40°C to 200°C can also be used, in which case a resin that can be dissolved in the molten aromatic hydrocarbon compound is also used. is desirable.

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

Specifically, the aromatic hydrocarbon compound is 2.6-
Rainpropylnaphthalene, 1. 4. 5-trimethylnaphthalene, 2. 3. 5-) Limethylnaphthalene, 2.3-dimethylnaphthalene, 1, 3. 6.
8-tetramethylnaphthalene, 1°2-di-0-tolylethane, bis(2,4,5-trimethylphenyl)methane, 1,18-diphenyl-octadecane, 1,3-terphenyl, ■.

2-di-p-tolylethane, diphenyl-p-)lylmethane, 1,2-dibenzylbenzene, 3゜4-diphenylhexane, 1.2-bis(2,3-dimethylphenyl)ethane, 4.4'- isopropylidenediphenol,
Bisresorcinol ethylene ether, 4-tert-butylphenyl salicylate, 2,2-bis(4-
acetoxydiphenyl)propane, bis(4-acetoxyphenyl)sulfone, terephthalic acid dimethyl ether,
Terephthalic acid dichlorophenyl ester, terephthalic acid distearylamide, malonic acid ethyl ester, 4-
Methoxyanilide, benzyl mandelate, phenyl benzoate, 2-naphthyl benzoate, 2-
Hydroxy-3-octylcarbamoylnaphthalene, 4
-hydroxybenzoic acid benzyl ester, p-benzyloxybenzoic acid benzyl ester, 1,4-bispropionyloxybenzene, 1,1-dibenzoylmethane and the like.

Examples of the resin include the resins listed above, and among them, hardened rosin, ester gum, ethyl cellulose, phenol resin, rosin-modified phenol resin, urea/melamine resin, chloride rubber, reduced rubber, maleic acid resin, petroleum resin, terpene resin, etc. Preferably used.

In addition, as a medium for electron beam or ultraviolet curing ink,
The radiation-curing compounds mentioned above are used as binders.

When curing by ultraviolet rays, it is preferable to add a photopolymerization initiator to the medium, and for example, photopolymerization initiators such as aromatic ketones, quinone compounds, ether compounds, and nitro compounds are used.

Specifically, initiation of photopolymerization of benzoquinone, phenanthrenequinone, naphthoquinone, diisopropylphenanthrenequinone, benzoin butyl ether, benzine, freonbutyl ether, Michler's ketone, Michler's thioketone, fluorenone, trinitrofluorenone, β-benzoylaminonaphthalene, etc. Examples include agents.

Oils are used as the medium for oxidative polymerization type (letterpress type) inks, and if necessary, solvents, waxes, dryers, thickeners, gelling agents, thixotropy imparting agents, etc. are added.

Oils include vegetable oils (drying oils such as linseed oil and sunflower oil, semi-drying oils such as soybean oil, unsaturated oils such as castor oil),
Examples include processing oils (dehydrated castor oil, polymerized oil, maleated oil, vinylated oil, urethanized oil), mineral oils (machine oil, spindle oil), and the like.

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

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

The coating amount of the capsule ink is appropriately adjusted depending on the type of ink prepared, and is not particularly limited, but is generally about 0.3 to 10 g/d, preferably 1 to 5 g/rd. It is adjusted within a range of degrees. By the way, 0.
If it is less than 3 g/m2, sufficient color development cannot be achieved when copying, and if it is more than 10 g/m2, there is no problem in terms of effectiveness, but it is not necessary from an economical point of view.

The chromogen material forming the receptor layer is pulverized using a ball mill, attritor, sand mill, etc. as necessary, and then a commonly used white pigment, a binder, and further a dispersant and an oil capsule as necessary. , colored dyes, fluorescent whitening agents, ultraviolet absorbers, antioxidants, antifoaming agents, and other various auxiliary agents are used in combination to prepare a coating liquid.

The amount of the chromogen substance blended into the receiving layer is not particularly limited, but from the viewpoint of color development and economic efficiency, the solid content of the paint is 1
Usually 1 to 50 parts by weight, preferably 3 parts by weight per 00 parts by weight
~35 parts by weight.

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

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

The amount of the receptive layer forming coating liquid to be applied is appropriately adjusted depending on the type of the coating liquid prepared, etc., and is not particularly limited. degree, preferably 3
It is adjusted within a range of about 1 g/m. By the way, 2g/m2
If you copy below, you will not be able to get enough color, and if you copy 15
g/m'' or more is not necessary from the viewpoint of effectiveness.

"Examples" Examples and comparative examples are listed below in order to make the effects of the present invention even clearer, but the present invention is not limited to these examples.

Note that parts and % in the examples represent parts by weight and % by weight unless otherwise specified.

Preparation of base paper Beat 80 parts of LPKP and 20 parts of NBKP, and add 1 part of rosin.
．． A base paper having an air permeability of 15 seconds and a basis weight of 40 g/l was made using a long-length paper machine.

Base paper for Examples 1 to 4 Using the above paper base paper, a 5% polyvinyl alcohol aqueous solution was coated with an air knife coater to obtain a base paper for pressure-sensitive copying paper having an air permeability as shown in Table 1. Obtained.

Base paper for Examples 5 and 6 The above papermaking base paper was subjected to size press treatment with a 25% oxidized starch aqueous solution to obtain a base paper for pressure-sensitive copying paper having air permeability as shown in Table 1.

Paper was made in the same manner as in Example 1 except that the beating conditions were strengthened when beating 80 parts of base paper LPKP and 20 parts of NBKP for Example 7. Air permeability was 80 seconds, Tsubo i! A 40 g/m untreated base paper was used as a base paper for pressure-sensitive copying paper.

Base paper for Comparative Example 1 Paper made in the same manner as Example, air permeability 35 seconds, basis weight 40 g
A base paper that was not treated with a /rd barrier agent was used as a base paper for pressure-sensitive copying paper.

Base paper for Comparative Example 2 Paper made in the same manner as Example, air permeability 15 seconds, basis weight 40 g
A base paper that was not treated with a barrier agent of /m'' was used as a base paper for pressure-sensitive copying light.

(Creating the bottom sheet) 65 parts of light calcium carbonate, 20 parts of zinc oxide, 3.5-
Blend zone of zinc di(α-methylbenzyl)salicylate and α-methylstyrene/styrene copolymer (melt ratio 80
/20) 20 parts (solid content) of carboxy-modified styrene-butadiene copolymer latex was added to the pulverized liquid obtained by grinding 15 parts of polyvinyl alcohol aqueous solution (solid content) and 300 parts of water in a ball mill for 24 hours. A developer coating solution prepared by adding the above was applied to each of the base papers for Examples 1 to 7 and Comparative Examples 1 to 2 using an air knife coater so that the dry weight was 5 g/nr to obtain a base paper.

(Preparation of capsule ink for pressure-sensitive copying paper) 8 parts of crystal violet lactone was mixed with 10 parts of alkyl diphenylethane.
0 parts (trade name: Hysol 5AS-296, manufactured by Nippon Petrochemical Co., Ltd.) was heated and dissolved to obtain an internal phase oil. This internal phase oil was emulsified in a solution in which a 20% aqueous solution of caustic soda was added to 200 parts of a 3.0 aqueous solution of ethylene-maleic anhydride copolymer (trade name EMA-31, manufactured by Monsando) to adjust the pH to 6.0. After that, the system was heated to 55°C.

Separately, 15 parts of melamine was added to 45 parts of a 37% formaldehyde aqueous solution and reacted at 60° C. for 15 minutes to prepare a prepolymer aqueous solution. This prepolymer aqueous solution was dropped into the emulsion, stirred, heated to 80°C, kept at that temperature for 1 hour, lowered the pH of 0.2N hydrochloric acid to 3.5, and kept warm for another 3 hours. After cooling, the average particle size is 2.6μ.
A capsule dispersion was obtained.

This dispersion was then filtered and further washed with ethanol, after which the capsules were redispersed in a mixed solvent of 330 parts of ethanol and 165 parts of n-propanol, to which were added 25 parts of light calcium carbonate and 14 parts of ethyl cellulose (Vercules). A flexographic capsule ink was obtained by adding 80 parts of flexo-type capsule ink.

(Creation of inner paper) Print the above capsule ink on the back side of each bottom paper at a speed of 80 m/min using a business form printing machine, and print 10 cm x 10 cm with an ink coverage of 2.5 g/%.
I got corner spot prints.

As a result of visual evaluation of short-circuit stains caused by printing on the thus obtained pressure-sensitive copying paper, the extent of short-circuit stains was as shown in Table 1.

Table 1 5 to 4: There is almost no short circuit stain.

3... Slight short-circuit staining occurs, but it is practical.

2-1...Shorts are badly stained and lack practicality.

(Effects) As is clear from the examples, the pressure-sensitive copying paper obtained according to the present invention was free from short stains.

Claims (1)

[Claims] (1) A non-aqueous material containing, as a core material, another chromogen substance that reacts with the chromogen substance to form a color on the back side of a sheet formed by providing a receptor layer containing a chromogen substance on a support. 1. A pressure-sensitive recording sheet obtained by printing a pressure-sensitive recording sheet with a microcapsule ink, characterized in that a base paper having an air permeability of 40 seconds or more based on JIS P8117 is used as the support.