JPH05156191A - Capsular ink composition - Google Patents

Abstract

PURPOSE:To solve drawbacks encountered when pressure-sensitive paper is produced by using a conventional capsular ink by the printing process. CONSTITUTION:A UV-curing capsular ink essentially consisting of microcapsules, an ethylenically unsaturated compound, a photopolymerization initiator and a thixotropic agent, wherein the viscosity of a mixture comprising the components of the ink except the microcapsules and the thixotropic agent is 3000cP or below, and the viscosity of the ink is above 3000cP. A pressure- sensitive ink produced by the printing process such as the typographic or offset printing process has very excellent color development and excellent printability.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a capsule ink composition, and more particularly to a capsule ink composition suitable for letterpress, offset printing and the like.

[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 developer such as activated clay, phenolic resin, and polyvalent metal salt of salicylic acid derivative is well known.

Generally, such pressure-sensitive copying papers are produced by the phase separation method,
Top paper coated with the color-forming agent-encapsulated microcapsules 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 surface of the support, the microcapsules and Medium paper, in which color materials are applied to different surfaces of a support, is put into practical use in an appropriate combination.

Separately, a so-called single pressure-sensitive copying paper in which the above-mentioned microcapsules and a color developer are laminated or mixed on the same surface of a support, and a capsule layer is further formed on the back surface of the single pressure-sensitive copying paper. Are provided, and they are put into practical use either alone or in an appropriate combination with the above-mentioned upper paper, middle paper, or lower paper.

Usually, the capsule layer of such pressure-sensitive copying paper is
It is formed by applying an aqueous capsule coating liquid to a support with a large-sized coating machine (hereinafter referred to as a coating method).
For example flexographic printing, gravure printing, screen printing,
There is a method (hereinafter referred to as a printing method) of applying to a support with a printing machine such as letterpress printing or offset printing. The printing method is
Even a small lot can be produced with little loss,
Suitable for low-volume, high-mix production than the coating method, for example,
It is suitable for producing pressure-sensitive copying paper with a special color tone that tends to be small in lot size.

In addition, since the printing method allows the capsules to be partially printed only on the necessary portions of the support, it is more economical than the coating method in which expensive capsules are applied to the entire surface of the support,
In addition, for example, by printing the capsule ink of different color tone on the high-quality paper or on the back surface of the lower paper partially, or on the entire surface coated by the coating method as described in JP-A-1-301360, the upper paper or the middle paper. Various features such as a pressure-sensitive copying paper (upper 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 capsule-coated surface of A certain variety can be produced.

However, although the printing method is a production method having many advantages as described above, in the case of letterpress printing or fusset printing, the capsule content ratio to the ink solid content (the components of the ink remaining after curing and drying) is high. Since it is low, it is strongly affected by components other than the capsule, and the oil release from the capsule is deteriorated, which causes a problem of poor color development. In particular, this tendency is remarkable when the ultraviolet-curable capsule ink composition is subjected to letterpress printing or fusset printing, and it is a fact that a practical level has not yet been obtained.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to eliminate the above-mentioned drawbacks that occur in the production of pressure-sensitive copying paper, especially when the conventional capsule ink is used in the printing method. That is, by finding a specific capsule ink composition and using it in a printing method such as letterpress or offset printing, it is possible to obtain a high-quality pressure-sensitive copying paper which has not been achieved so far.

[0009]

The present invention provides a UV-curable capsule ink composition comprising a microcapsule, an ethylenically unsaturated compound, a photopolymerization initiator and a thixotropic agent as basic components. And a thixotropic agent-free mixture having a viscosity of 3000 cps or less and an ink composition having a viscosity of more than 3000 cps.

[0010]

The electron-donating color former contained in the microcapsules is known in the art, for example, 3,3.
-Bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3- (p-dimethylaminophenyl)
-3- (1,2-Dimethylindol-3-yl) phthalide, 3,3-bis (1,2-dimethylindole-3)
-Yl) -5-dimethylaminophthalide, 3,3-bis (9-ethylcarbazol-3-yl) -6-dimethylaminophthalide and other triallylmethane dyes, 4,4-
Bis-dimethylaminobenzhydrylbenzyl ether, N-halophenyl leuco auramine, N-2,4
Diphenylmethane dyes such as 5-trichlorophenyl leuco auramine, benzoyl leuco methylene blue, P
-Thiazine dyes such as nitrobenzoyl leuco methylene blue, spiro dyes such as 3-methyl-spiro-dinaphthopyran, 3-phenyl-spiro-dinaphthopyran, 3-propyl-spiro-dibenzopyran, rhodamine-B
-Lactam dyes such as anilinolactam, 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 Fluorane dyes such as -7-phenylaminofluorane, 3-piperidino-methyl-7-phenylaminofluorane, 3-diethylamino-6-methyl-7-xylidinofluorane, 3,3-bis [2- ( Infrared coloring dyes such as p-dimethylaminophenyl) -2- (p-methoxyphenyl) ethylene-2-yl] -4,5,6,7-tetrachlorophthalide and the like can be mentioned, and these are used alone. Alternatively, they are used together.

The electron-donating color former as described above 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, naphthene oil, chlorinated paraffin and other mineral oils: alkylated biphenyl, alkylated terphenyl, alkylated naphthalene, diarylethane, triarylmethane, aromatic hydrocarbons such as diphenylalkane Kinds: Esters such as dimethyl phthalate, diethyl phthalate, di-n-butyl phthalate, 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 an oil 100.
2 to 80 parts by weight, preferably 5 to 5 parts by weight
It is added in the range of 50 parts by weight.

As the encapsulation method, a known coacervation method, interfacial polymerization method, in-situ method or 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 capsules varies depending on the film material used or the film thickness and cannot be generally stated, but usually 1 to
It is 10 μm. In addition, the capsule may contain an antioxidant, an ultraviolet absorber, a fragrance, etc., if necessary.

The capsules obtained by the above method are
It is usually an aqueous dispersion, which is in a semi-third state after filtration or is dried by aeration, surface drying, fluidized drying, gas stream drying, spray drying, vacuum drying, freeze drying, infrared ray drying, high frequency drying, ultrasonic wave. After being subjected to treatments such as drying and fine pulverization drying, it is dispersed in the following non-aqueous ink medium in a dried state, and various auxiliaries are further added if necessary to form a capsule ink. As described in JP-A-53-135718, a method of mixing an aqueous capsule dispersion and a non-aqueous medium and then removing water under reduced pressure or a non-aqueous medium that is mixed with water after filtering the capsule dispersion. The capsules can be dispersed in the non-aqueous ink medium by the method of washing and replacing with.

The capsule content in the capsule ink is usually adjusted to be in the range of 5 to 60 parts by weight with respect to 100 parts by weight of the ink.

Examples of the ethylenically unsaturated compound used in the present invention include methyl methacrylate, butyl methacrylate, 2-ethoxyethyl acrylate, 2-phenoxyethyl (meth) acrylate, 2- (nonylphenoxy) ethyl (meth) acrylate, Cyclohexyl methacrylate, benzyl methacrylate, trifluoroethyl methacrylate, 3-sulfopropyl methacrylate potassium salt, N- (3-sulfopropyl) -N
-Methacryloylamidopropyl-N, N-dimethylammonium betaine, glycidyl methacrylate, allyl methacrylate, dimethylaminoethyl methacrylate, 3-chloro-2-hydroxypropyl methacrylate, benzyl acrylate, cyclohexyl acrylate, tetrahydrofurfuryl acrylate, 1-methoxycyclododeca Dienyl acrylate, dicyclopentenyl acrylate, dicyclopentenyl oxyethyl acrylate, 2-hydroxyethyl acrylate, 2-
Hydroxypropyl acrylate, 2,6-dibromo-
4-t-butylphenyl acrylate, ethylene glycol diacrylate, ethylene glycol dimethacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, ethoxydiethylene glycol acrylate, phenoxydiethylene glycol (meth) acrylate, phenoxypolyethylene glycol (meth) acrylate, butylphenoxydie Ethylene glycol (meth) acrylate, hexylphenoxydiethylene glycol (meth) acrylate, octylphenoxydiethylene glycol (meth)
Acrylate, nonylphenoxydiethylene glycol (meth) acrylate, laurylphenoxydiethylene glycol (meth) acrylate, naphthoxydiethylene glycol (meth) acrylate, butylnaphthoxydiethylene glycol (meth) acrylate, bromnaphthoxydiethylene glycol (meth) acrylate,
Hydroxyphenoxy polyethylene glycol (meth)
Acrylate, butylphenoxy polyethylene glycol (meth) acrylate, hexylphenoxy polyethylene glycol (meth) acrylate, octylphenoxy polyethylene glycol (meth) acrylate,
Nonylphenoxy polyethylene glycol (meth) acrylate, laurylphenoxy polyethylene glycol (meth) acrylate, propylene glycol diacrylate, propylene glycol dimethacrylate, polypropylene glycol diacrylate, polypropylene glycol dimethacrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate , 2-hydroxy-3- (p-bromophenoxy) propyl (meth) acrylate, 2-hydroxy-3- (o-methylphenoxy) propyl (meth) acrylate, 2-hydroxy-3- (p-methylphenoxy) propyl (Meth) acrylate, 2-hydroxy-3- (p-ethylphenoxy) propyl (meth) acrylate, 2-hydroxy-
3- (p-propylphenoxy) propyl (meth) acrylate, 2-hydroxy-3- (p-butylphenoxy) propyl (meth) acrylate, 2-hydroxy-
3- (o, p-dimethylphenoxy) propyl (meth)
Acrylate, 2-hydroxy-3- (p-hexylphenoxy) propyl (meth) acrylate, 2-hydroxy-3- (p-octylphenoxy) propyl (meth) acrylate, 2-hydroxy-3- (p-nonylphenoxy) Propyl (meth) acrylate, 2-hydroxy-3- (p-laurylphenoxy) propyl (meth) acrylate, 2-hydroxy-3-naphthoxypropyl (meth) acrylate, 2-hydroxy-3-
(Butylnaphthoxy) propyl (meth) acrylate,
2-hydroxy-3-ethoxypropyl (meth) acrylate, 2-hydroxy-3-propoxypropyl (meth) acrylate, 2-hydroxy-3-butoxypropyl (meth) acrylate, 2-hydroxy-3-lauroxypropyl (meth ) Acrylate, 2-hydroxy-3- (4-chlorobutoxy) propyl (meth) acrylate, 1,2-butanediol diacrylate, 1,
2-butanediol dimethacrylate, 1,3-butanediol diacrylate, 1,3-butanediol dimethacrylate, 1,4-butanediol diacrylate, 1,4-butanediol dimethacrylate, 1,6
-Hexanediol diacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol diacrylate, glycerol dimethacrylate, glycerol methacrylate acrylate, trimethylolpropane diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate,
Pentaerythritol tetraacrylate, hydroxypivalic acid neopentyl glycol ester diacrylate, 2,2-bis [4- (acryloyloxydiethoxy) phenyl] propane, hydroxypivalic acid neopentyl glycol ester caprolactone adduct diacrylate, hydroxypivale Dialdehyde of acetal compound of valaldehyde and trimethylolpropane, diallyloxy diacryloyloxycyclohexane, trimethylolpropane propylene oxide adduct triacrylate, ester of lower fatty acid and acrylic acid of dipentaerythritol, caprolactone addition of dipentaerythritol Acrylate, 2-hydroxyethyl acrylate via 2,4-tolylene diisocyanate Liquid polybutadiene acrylate obtained by addition reaction of hydroxyl group of tadiene with urethane, liquid polybutadiene acrylate obtained by esterification reaction of maleic anhydride-added maleic polybutadiene with 2-hydroxy acrylate, liquid polybutadiene acrylate Liquid polybutadiene acrylate obtained by an epoxy esterification reaction of a carboxyl group and glycidyl acrylate, a liquid polybutadiene acrylate obtained by an esterification reaction of epoxidized polybutadiene obtained by acting an epoxidizing agent on liquid polybutadiene, and acrylic acid, Liquid polybutadiene acrylate obtained by dehydrochlorination reaction of liquid polybutadiene having a hydroxyl group and acrylic acid chloride, liquid hydrogenation 1 2 liquid hydrogenated 1,2 polybutadiene acrylate obtained by modifying 2 polybutadiene glycol with urethane acrylate, dioctyl 2-acryloyloxyethyl phosphate, diphenyl 2-acryloyloxyethyl phosphate, and the like. Among them, those combined with a monomer and an oligomer are particularly preferable. ,
A good balance between color developability and stain resistance is preferable, which is preferable.

The ethylenically unsaturated compound is usually blended in the capsule ink in the range of 30 to 95% by weight.

The photopolymerization initiator used in the present invention includes:
Aromatic ketones such as benzoquinone, phenanthrenequinone, naphthoquinone, diisopropylphenanthrenequinone, benzoisobutyl ether, benzoin, furoin butyl ether, Michler's ketone, Michler's thioketone, fluorenone, trinitrofluorenone, β-benzoylaminonaphthalene, quinone Examples thereof include compounds, ether compounds and nitro compounds.

The photopolymerization initiator is usually added in the range of 1 to 20 parts by weight with respect to 100 parts by weight of the ethylenically unsaturated compound.

A sensitizer may be added to further accelerate the polymerization. Examples of the sensitizer include triethanolamine, N-methyldiethanolamine, N,
Examples thereof include N-dimethylethanolamine and N-methylmorpholine. The sensitizer is an ethylenically unsaturated compound 1
It is usually added in the range of 0 to 10 parts by weight with respect to 00 parts by weight.

As the thixotropic agent used in the present invention, for example, colloidal silica, metal soap (aluminum stearate, aluminum octanoate, etc.), sodium palmitate, aluminum chelate (aluminum diisopropoxide monoacetoacetate etc.), organic Examples include amine-modified bentonite, thixotropic polyamide resin, etc. Among them, when colloidal silica is dispersed in a liquid, the particles of the present invention exhibit excellent structural viscosity due to the action of silanol groups on the surface of the particle, and exhibit excellent structural viscosity. It is preferably used for the purpose of.

Further, although the specific surface area by BET method of the colloidal silica is those 50 to 380 m ² / g by grade, 80~380m ² / g in consideration of various suitability
Are preferred. These are usually blended in the capsule ink in the range of 0.1 to 20% by weight.

As the ink medium used in the capsule ink of the present invention, a high boiling medium, a low boiling medium, a resin, waxes and oils may be used in combination, if necessary, in addition to the above basic component compounds. These are usually 0 to 0 in the capsule ink.
It is compounded in the range of 60% by weight.

Incidentally, examples of the high boiling point medium include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, 2,3-butylene glycol, methyl cellosolve, cellosolve, butyl cellosolve, carbitol, butyl carbyl. Toll and the like can be mentioned.

As the low boiling point medium, for example, methanol,
Examples thereof include ethanol, n-propanol, iso-propanol, n-butanol, ethyl acetate, propyl acetate, butyl acetate, acetone, methyl ethyl ketone.

Examples of resins 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, and 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, modified polyvinyl alcohol, polyvinyl butyral, Examples thereof include polyvinylpyrrolidone, ethyl cellulose, nitrocellulose, hydroxypropyl cellulose, cellulose acetate propionate and cellulose acetate butyrate.

Examples of the waxes include beeswax, whale wax, lanolin, candelilla wax, carnauba wax, wood wax, rice wax, montan wax,
Ozokerite, paraffin wax, microcrystalline wax, montan wax derivative, paraffin wax derivative, microcrystalline wax derivative, castor wax, opal wax, low molecular weight polyethylene, distearyl ketone, caprylic acid amide, stearic acid amide, ethylenebisstearic acid amide , Stearic acid, behenic acid, stearyl alcohol, distearyl phosphate and the like.

Examples of the oils include vegetable oils such as linseed oil, safflower oil, soybean oil and castor oil: processed oils such as dehydrated castor oil, polymerized oil, maleated oil, vinyl oil and urethane oil: machine oil, spindle oil Mineral oil and the like.

The capsule ink of the present invention may further contain, if necessary, a tilting material such as cellulose powder, starch particles or synthetic resin particles, a white pigment such as titanium oxide, zinc oxide, calcium carbonate, aluminum hydroxide or silica. A desensitizing component for color development such as a sensitizer, an ultraviolet absorber, an antioxidant, a fluorescent whitening agent, a plasticizer, and a coloring dye can be appropriately added as necessary.

In the present invention, B-type viscometer 60 rpm
The viscosity value measured at 25 ° C. is very important. First of all, it is preferable that the viscosity of the ink medium is low, that is, the viscosity of the ink medium, which is a mixture of the microcapsules in the ink composition and other components not containing a thixotropic agent, is 3000 cps or less. However, those of 2000 cps or less are more preferable,
Furthermore, the thing of the range of 1-1500 cps is especially preferable. By the way, if an ink medium having a viscosity of more than 3000 cps is used, the color development of the obtained pressure-sensitive copying paper becomes extremely poor.

The ink is usually prepared by adding microcapsules, a thixotropic agent and other auxiliaries to the ink medium and thoroughly mixing them using a propeller disperser, an ultrasonic disperser, a ball mill or a triple roll. To be done.

Secondly, in the present invention, it is important that the viscosity of the capsule ink is high to some extent. It is important that the ink medium, which is a mixture of an ethylenically unsaturated compound, a photopolymerization initiator and other auxiliaries, has a low viscosity, and the viscosity of the capsule ink prepared using it should be high. is important. The viscosity of the capsule ink is adjusted to exceed 3000 cps. 35 among others
It is more preferable to adjust it to 00 cps or more, and further 40
00 cps or more is particularly preferable. By the way, when the viscosity of the prepared capsule ink is less than 3000 cps,
In letterpress printing, “bottle drop” is likely to occur, and in offset printing, “ink mist” is likely to occur, and stable operation is difficult to perform.

Of course, although the viscosity of the capsule ink is preferably high, there is no upper limit, and there is a limit to the high viscosity. However, the B-type viscometer is difficult to measure such high viscosity. Therefore, the value of the upper limit viscosity is measured with an ink tack, and among them, the one prepared so that the tack value of the capsule ink is 6 or less is particularly preferable because of excellent color development.

[0034] Capsules ink thus prepared is on a variety of supports by letterpress printing or offset printing, usually dry weight 1 to 10 g / m ^2, preferably 2 to 6 g / m ²
It is printed so that it becomes the range of. The ink of the present invention can also be used as a printing ink for screens and the like. When the ink is dried and cured by irradiation with ultraviolet rays, an excellent ink film can be obtained.

The support used for printing is, for example, high-quality paper, synthetic paper, film, art paper, coated paper, cast paper, lightly coated paper, pressure-sensitive copying paper (upper paper, middle paper, lower paper, Cercon paper) and the like.

The substance contained in the capsule of the capsule ink of the present invention is not limited to the material for pressure-sensitive copying paper, and may be, for example, a fragrance, a liquid crystal, a temperature indicating material, a rust preventive, an insect repellent, a rodenticide, an adhesive agent. Agents, adhesives and the like.

[0037]

EXAMPLES In order to further clarify the effects of the present invention, examples and comparative examples will be described below, but the present invention is not limited to these examples. In addition, unless otherwise indicated, the part and% in an example represent a weight part and weight%, respectively. The viscosity was measured at a B-type viscometer of 60 rpm and 25 ° C.

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, 3 of ethylene-maleic anhydride copolymer (trade name EMA-31, manufactured by Monsanto Co.) whose pH was adjusted to 6.0
% Emulsification of the internal phase oil in 200 parts of aqueous solution and
The temperature was raised to 5 ° C.

Separately, 45% 37% aqueous formaldehyde solution
15 parts of melamine was added to each part and reacted at 60 ° C. for 15 minutes to prepare an aqueous prepolymer solution. This prepolymer aqueous solution was added dropwise to the emulsion, and the mixture was further stirred with 0.1.
After adding N hydrochloric acid dropwise to adjust the pH to 5.3, the system was heated to 80 ° C.
The mixture is heated to 1 hour and stirred for 1 hour, 0.2N hydrochloric acid is added dropwise to lower the pH to 3.5, and the mixture is stirred for 3 hours and then cooled to disperse capsules having an average particle diameter of 3.8 μm. A liquid was obtained.

Next, this dispersion was filter-pressed and subsequently air-dried to form a powder capsule, and 200 parts of this capsule and colloidal silica (trade name, Aerosil 200, manufactured by Nippon Aerosil Co., Ltd., BET, which is a thixotropic agent, were used. 10 parts by specific surface area of 200 m ² / g) by the method, 400 parts of ethylenically unsaturated compound and 1
A capsule ink having a viscosity of 4000 cps was prepared by adding and mixing to 410 parts of 0 part of the mixture (viscosity 850 cps).

(Preparation of top paper) The above capsule ink was printed on a base paper of 40 g / m ² with a letterpress printing machine (ink amount 5.0).
g / m ² ) and cured using a 6 kw ultraviolet irradiation device to obtain an upper paper. However, the vase never occurred.

(Preparation of Oil Capsule) Ethylene-maleic anhydride copolymer (trade name E) whose pH is adjusted to 6.0
100 parts of alkyldiphenylethane was emulsified as an internal phase oil in 200 parts of a 3% aqueous solution of MA-31, manufactured by Monsanto Co., Ltd., and the 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 0 ° C. for 15 minutes.

This prepolymer aqueous solution was added dropwise to the emulsion, and 0.1N hydrochloric acid was added dropwise with stirring to add p.
After adjusting H to 5.3, the system was heated to 80 ° C. and stirred for 1 hour, 0.2N hydrochloric acid was added dropwise to lower the pH to 3.5, and the mixture was stirred for another 3 hours and then cooled. Thus, a dispersion liquid of capsules having an average particle diameter of 5.0 μm was obtained.

(Preparation of lower paper) Light calcium carbonate 60
Parts, 10 parts of zinc oxide, 10 parts of a mixed melt of zinc 3,5-di (α-methylbenzyl) salicylate and an α-methylstyrene-styrene copolymer (blend ratio of 80/20), the oil capsule 10 described above. Part, 0.2 parts of pulp powder 10 parts
After dispersing in 300 parts of an aqueous polyvinyl alcohol solution and further adding 10 parts (solid content) of gelatinized starch and 15 parts (solid content) of carboxy-modified styrene-butadiene latex,
40 g / m of a 30% by weight developer coating solution prepared by diluting
Dry weight ² of the base paper was obtained under the sheet was plated with an air knife coater so that 7 g / m ^2.

(Evaluation) When the upper paper and the lower paper thus obtained were overlaid and printed with a typewriter, an extremely clear color image was obtained on the lower paper surface corresponding to the portion where the capsule ink was printed.

Example 2 (Preparation of top paper) The above capsule ink was printed on a base paper of 40 g / m ² by an offset printing machine (ink amount 4.0 g / m).
² ) and cured using a 6 kw ultraviolet irradiation device to obtain an upper paper. There was no ink mist trouble and stable operation was possible.

(Evaluation) When the upper paper thus obtained and the lower paper obtained in the same manner as in Example 1 were overlaid and printed with a typewriter, it was extremely clear on the lower paper surface corresponding to the portion where the capsule ink was printed. A colored image was obtained.

Example 3 A resin having a viscosity of 5500 cps was used in the same manner as in Example 1 except that a mixture of 300 parts of an ethylenically unsaturated compound, 10 parts of a photopolymerization initiator and 200 parts of pentaerythritol ester of rosin (1200 cps) was used. A capsule ink was prepared, and the upper paper was prepared and evaluated in the same manner as in Example 1 below. The color image obtained was extremely clear.

Example 4 A capsule ink having a viscosity of 8000 cps was prepared in the same manner as in Example 1 except that 620 parts of a mixture of 600 parts of an ethylenically unsaturated compound and 20 parts of a photopolymerization initiator (2500 cps) was used. The upper paper was prepared and evaluated in the same manner as in Example 1. Although the obtained color image has practicality, it was considerably inferior to that in Example 1. No vase was seen during printing.

Comparative Example 1 A capsule ink having a viscosity of 2300 cps was prepared in the same manner as in Example 1 except that colloidal silica was not added. After that, printing was performed in the same manner as in Example 1, but a vase sag occurred.

Comparative Example 2 A capsule ink having a viscosity of 10000 cps was prepared in the same manner as in Example 1 except that 620 parts of a mixture of 600 parts of an ethylenically unsaturated compound and 20 parts of a photopolymerization initiator (3300 cps) was used. The upper paper was prepared and evaluated in the same manner as in Example 1. The obtained color image was inferior to the level where it was not practical.

[0052]

The pressure-sensitive copying paper produced by the printing method using the capsule ink of the present invention showed extremely excellent color forming property. In addition, the printability was excellent in operability without any troubles such as pot dripping and ink mist.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical display location G03F 7/027 // B41M 5/124 (72) Inventor Hirokazu Furukawa 4th street, Jokoji, Amagasaki city, Hyogo prefecture 3-1 No. 1 Kanzaki Paper Manufacturing Co., Ltd. Kanzaki Mill (72) Inventor Shunsuke Shioi 4-3-1 Jōkoji, Amagasaki City, Hyogo Prefecture Kanzaki Mill Co., Ltd. Kanzaki Mill

Claims (3)

[Claims] 1. An ultraviolet-curable capsule ink composition comprising a microcapsule, an ethylenically unsaturated compound, a photopolymerization initiator and a thixotropic agent as basic components, wherein the ink composition contains no microcapsules and no thixotropic agent. The capsule ink composition, wherein the viscosity of the mixture is 3000 cps or less, and the viscosity of the ink composition exceeds 3000 cps. Viscosity measurement conditions: B-type viscometer 60 rpm, 25 ° C. 2. The viscosity of a mixture of the microcapsules in the ink composition and a component not containing a thixotropic agent has a viscosity of 2.
000 cps or less, and the viscosity of the ink composition is 3
The capsule ink composition according to claim 1, which has a viscosity of 500 cps or more. 3. The capsule ink composition according to claim 1, wherein the thixotropic agent is colloidal silica.