JPH07257026A - Production of capsule ink for pressure-sensitive duplication - Google Patents

Abstract

PURPOSE:To efficiently produce microcapsule ink for pressure-sensitive duplication including a color former and reducing developed color staining at the time of the production of a pressure-sensitive copy sheet and during the long- term preservation thereof. CONSTITUTION:An aq. dispersion of a microcapsule including an electron donating color former is substituted with an org. solvent dispersion and, thereafter, the substituted dispersion is washed with the same volatile org. solvent as an ink medium to obtain a cake like microcapsule of which the moisture content immediately after washing is set to 5% or less by wt. of the microcapsule. This cake like microcapsule (a), the volatile org. solvent (b) as the ink medium, an adhesive (c), an ultraviolet curable compd. (d) and a photopolymerization initiator (e) are used as fundamental components.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a pressure-sensitive copying capsule ink in which microcapsules containing an electron-donating color-forming agent are formed into an ink, which is used for producing a pressure-sensitive copying sheet and for a long time of the pressure-sensitive copying sheet. The present invention relates to a method for efficiently producing a pressure-sensitive copying capsule ink with little color stain during storage.

[0002]

2. Description of the Related Art Electron-donating color formers such as crystal violet lactone and benzoyl leuco methylene blue,
A pressure-sensitive copying sheet utilizing the principle of developing color by a reaction in combination with an electron-accepting developer such as activated clay, a phenol-formaldehyde condensate, or a polyvalent metal salt of an aromatic carboxylic acid is well known.

In general, such a pressure-sensitive copying sheet has, as a support, microcapsules containing an electron-donating color former prepared by a phase separation method, an interfacial polymerization method, an in situ method or the like. An applied upper sheet (CB sheet), a lower sheet (CF sheet) in which an electron-accepting color developing agent that reacts with an electron-donating color developing agent to develop a color is applied to a support,
A medium-use sheet (CFB sheet) in which the color-forming agent microcapsules and the color-developing agent are applied to different surfaces of a support is put into practical use as a set in an appropriate combination.

There is also a so-called self-coloring type pressure-sensitive copying sheet in which a color-developing agent microcapsule and a color-developing agent are separately applied on the same surface of a support as a laminated or mixed layer, and the self-coloring type pressure-sensitive copying sheet. There is a set of a self-coloring type pressure-sensitive copying sheet in which a capsule layer is provided on the back surface of the sheet and a lower sheet and a middle sheet are properly combined.

Usually, these pressure-sensitive copying sheets are manufactured by applying a water-based paint to a support with a large-sized coating machine. As a special manufacturing method, microcapsules containing a color-forming agent are used. There is a method of making ink and spot printing with a printing machine. Since spot printing of capsule ink can print expensive capsule paint only on the required parts of the support, compared with the method of coating the entire surface of the support with a large-scale coating machine, for example, partial color tone There is a small swirling effect such that different pressure sensitive copy sheets can be obtained, and depending on the intended product type, it exhibits economically excellent characteristics.

However, while such a printing method has great merits as compared with a method using a coating machine, there is a point that it is still not sufficient depending on the ink and the method of the printing machine. For example, in order to print a color-forming agent capsule ink onto a support by printing to obtain a pressure-sensitive copy sheet having good color-forming property, it is necessary to make the ink application amount larger than the ink amount in general color printing. In the case of the evaporation-drying type capsule ink in which the medium solvent of the ink is evaporated and dried to be hardened, a large drying device is required because a large amount of the solvent is evaporated when the ink application amount is increased. In addition, when the solvent used as the ink medium is mainly alcohols and the ink is water containing a certain amount of water and the support is paper, a large amount of alcohol or water penetrates into the paper, causing wrinkles on the paper. It comes with the drawback of becoming easier to do. And, when using the ultraviolet curing type capsule ink, it is possible to manufacture with a small ultraviolet irradiation device as compared with the case of using the evaporation drying type ink, but the mixing ratio of the resin is the evaporation drying type. Since it is higher than the ink, the printed area is likely to become transparent, and it is difficult for the capsule to break under pressure during pressure-sensitive copying due to the influence of the resin, resulting in poor color development. There is.

By using a capsule ink containing a volatile organic solvent such as an alcohol, a UV-curable compound and a photopolymerization initiator as an ink medium for the microcapsule ink containing the above-mentioned color-forming agent, the color-forming property and the printing property can be improved. It is described in JP-A-3-202394 that a pressure-sensitive copy sheet having good opacity in a portion and free of wrinkles on a support paper can be obtained by using a relatively small dryer. However, this method cannot be said to be sufficient depending on the conditions. For example, when printing at high speed, the polymerization of the ultraviolet curable substance becomes insufficient, and the resulting pressure-sensitive copy sheet is liable to be contaminated by friction. Have

Further, the decrease in film strength caused by insufficient polymerization of the UV-curable substance in the ink when printing at a high speed is caused by adding an adhesive agent into the pressure-sensitive copying sheet. It is described in JP-A-4-70374 that the abrasion resistance is improved.

However, a capsule ink containing a volatile organic solvent such as an alcohol and an ultraviolet-curable compound as an ink medium for a microcapsule containing a color-forming agent, and a photopolymerization initiator and an adhesive as basic components is not converted into an ink. Depending on the method, it has been pointed out that the influence of the residual color former adhering to the surface of the microcapsule during the production of the microcapsule or the effect of the color former eluted by the volatile organic solvent of the ink medium from the cracks of the microcapsule, etc. This defect causes color stains during printing or during long-term storage of the pressure-sensitive copy sheet, which deteriorates the product quality of the pressure-sensitive copy sheet.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a color-forming agent-containing capsule ink for pressure-sensitive copying,
An object of the present invention is to provide a method for efficiently producing a capsule ink for pressure-sensitive copying, which is less likely to cause color stains during the production of the pressure-sensitive copying sheet or during long-term storage of the pressure-sensitive copying sheet.

[0011]

The present invention provides (a) microcapsules containing an electron-donating color former, (b) a volatile organic solvent as an ink medium, (c) an adhesive, and (d) ultraviolet curing. In a method for producing a pressure-sensitive copying capsule ink containing a photosensitive compound and (e) a photopolymerization initiator as a basic component, an aqueous dispersion of microcapsules containing an electron-donating color former is replaced with an organic solvent dispersion, Further, a volatile organic solvent as an ink medium is used for washing, and a cake-like capsule having a water content immediately after washing of 5% by weight or less with respect to the microcapsule is used to form an ink. This is a method for producing a capsule ink for pressure copying.

The volatile organic solvent as the ink medium is alcohols, and the compounding ratio of the volatile organic solvent as the ink medium and the ultraviolet curable compound is 80:20 to.
The range of 20:80 is more preferable.

[0013]

A pressure-sensitive copying sheet obtained by using the pressure-sensitive copying capsule ink of the present invention is, for example, an upper sheet obtained by printing a microcapsule ink containing an electron-donating color-forming agent on a support. The capsule surface of a color-developing sheet, self-coloring type pressure-sensitive copying sheet, etc. and the developing surface of an intermediate sheet, lower sheet are made to face each other, and the capsule is destroyed from the back surface of the capsule surface by writing pressure or pressure from an impact printer etc. Then
By transferring the encapsulated coloring agent dye solution to the developing surface, a recorded image corresponding to the pressure is developed on the developing surface.

Examples of the electron-donating color former used in the present invention include those known in the field of pressure-sensitive copying sheets, for example, triallylmethane dyes, diphenylmethane dyes, thiazine dyes and spiro. There are substances such as series dyes, lactam series dyes, fluoran series dyes, infrared coloring series dyes and the like, and mixtures thereof.

Further, as the electron-accepting developer, for example, clays such as acid clay, activated clay, attapulgite, zeolite and bentonite which are well known in the field of pressure-sensitive copying sheets are described below. , Phenol resins, polyvalent metal salts of various aromatic carboxylic acids described in JP-B-51-25174, zinc salts of 2,2'-bisphenol sulfone compounds described in JP-A-54-106316, and mixtures thereof. There are substances such as.

In the method for producing a capsule ink for pressure-sensitive copying of the present invention, the above-mentioned electron-donating color former is encapsulated in microcapsules to form an ink. Then, it is used as an ink for printing and coating on a support using a printing machine.

To microencapsulate the electron-donating color former, the color former is encapsulated in a state of being dissolved in the internal phase oil. Examples of the oil for the internal phase include vegetable oils, animal oils, mineral oils, aromatic hydrocarbons, alcohols, organic acids, esters, organic phosphoric acid compounds, ethers, amides, ketones, alkylene carbonates. There are substances such as classes and the like and mixtures thereof. The compounding amount of the color former is usually adjusted within the range of about 1 to 80 parts by weight with respect to 100 parts by weight of the internal phase oil.

As the encapsulation method, conventionally known coacervation method, interfacial polymerization method, in-situ (in
Although the in situ method can be appropriately selected and used, it is preferable to use a synthetic resin as the wall film material. Among them, the capsule having the melamine formaldehyde resin as a film has a superior pressure-sensitive property in terms of color vividness and the like. It is particularly preferable because a copy sheet can be obtained.

If desired, these microcapsules may contain an antioxidant, an ultraviolet absorber and the like. Examples of the UV absorber include benzophenone-based, benzotriazole-based, and cyanoacrylate-based UV absorbers.

Examples of the volatile organic solvent as an ink medium used in the present invention include benzene, toluene, xylene, cyclohexane, hexane, trichloroethylene, ligroin, methyl isobutyl ketone, methyl acetate, ethyl acetate, butyl acetate, methyl cellosolve. ,
Ethyl cellosolve, butyl cellosolve, diethylene glycol, diethylene glycol monobutyl ether, diethylene glycol monobutyl ether acetate, methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, n-hexanol, cyclohexanol, 2-ethylhexyl alcohol, and the like, and mixtures thereof. To be Among them, alcohols having 3 or less carbon atoms are particularly preferable in terms of drying property under high speed printing.

Examples of the UV-curable compound include compounds having one or more, preferably a plurality of vinyl groups or vinylidene groups, specifically, an acryloyl group,
There are compounds having a methacryloyl group, an allyl group, an unsaturated polyester, a vinyloxyacrylamide group, and the like. The photopolymerization initiator includes, for example, aromatic ketones, quinone compounds, ether compounds, nitro compounds and the like. The compounding amount of the photopolymerization initiator is usually in the range of about 0.1 to 10 parts by weight with respect to 100 parts by weight of the ultraviolet curable compound.

The compounding ratio of the volatile organic solvent and the ultraviolet curable compound is usually in the range of 95: 5 to 10:90 (parts by weight), and the ink applied by printing is dried by a dryer and an ultraviolet irradiation device. Cured using. However, 80:20 to 20: 8 is used especially when the drying is light or the coating ink on the support is cured only by the ultraviolet irradiation device.
The range of 0 (parts by weight) is preferable.

Further, as the adhesive used in the capsule ink of the present invention, for example, acrylic resin, methacrylic resin, vinyl acetate resin, polystyrene resin, xylene resin, coumarone resin, petroleum resin, phenol resin, resorcinol resin, urea resin, melamine. Resin, ketone resin,
Examples include unsaturated polyester resins, polyamide resins, polyvinyl formal resins, polyvinyl butyral resins and cellulose derivatives. The compounding amount of the adhesive is 0.1 to 50 parts by weight with respect to 100 parts by weight of the ultraviolet curable compound.
It is 0 part by weight, more preferably 1 to 300 parts by weight.

The capsule ink in the present invention contains a sensitizer for enhancing the efficiency of photopolymerization, if necessary, and further a white pigment, a color desensitizing component, a capsule protecting agent, an antioxidant, a fluorescent dye, a plasticizer. Etc. can be added.

In the production method of the present invention, as a method for converting a capsule ink containing the above-mentioned basic components into an ink,
Without completely replacing the water-dispersed microcapsules with an organic solvent or forming dry powder capsules, wet cake-like or wet paste-like microcapsules containing a certain amount of water can be used as they are to form an ink, thereby greatly omitting the process. Capsule ink can be manufactured efficiently.

However, in this step, as described above, the coloring agent that is adhered to the surface of the capsule and is dissolved in the ink by the volatile organic solvent as the ink medium from the residual coloring agent at the time of manufacturing the capsule or the crack of the capsule. Due to the influence of the above, there is a problem that color stains occur during printing in the production of copy sheets and during long-term storage of pressure-sensitive copy sheets.

As a result of various investigations to solve the above problems, the present inventor partially replaced the aqueous capsule dispersion with an organic solvent, and then washed and filtered with a volatile organic solvent used as an ink medium. Then, immediately after washing, the wet cake-like capsules, from which water was removed so that the water content measured by the Karl Fischer method was 5% by weight or less with respect to the microcapsules, were used as they were to form an ink, and the above problems were solved. Found the best way to solve. It should be noted that it is not directly meaningful for the effect of the present invention that the moisture content of the capsule before ink formation exceeds a specific value due to moisture absorption or the like after the moisture content immediately after washing is set to a specific value. Further, even if reducing the water content to close to 1% is more effective for the effect of the present invention, there are many process losses and it is not within a practical range.

In the method of the present invention, the step of washing and filtering a cake-like capsule with a volatile organic solvent used as an ink medium is important, and the washing filtrate is applied to the color developing surface of the pressure-sensitive copying sheet for test evaluation. It is important to carry out washing to such an extent that coloring stains do not occur. This is achieved by washing and filtering with the organic solvent used as the ink medium as described above, and removing water so that the water content measured by the Karl Fischer method immediately after washing is 5% by weight or less based on the capsule. It This washed water content is 5
A conventionally known method is appropriately used for the inking step other than using the cake-shaped capsules in an amount of not more than wt%. By this method, even if the ink is directly converted into an ink using a wet cake-shaped capsule, the coloring agent that may be eluted in the ink from the residual coloring agent or capsule cracks that adhere to the surface of the capsule during capsule manufacturing is removed. It becomes possible to produce a customized ink.

The amount of capsules mixed in the ink medium is
Usually ink medium (volatile organic solvent as ink medium + adhesive + UV-curable compound + photoinitiator) 100
The amount is 2 to 100 parts by weight, preferably 7 to 60 parts by weight with respect to parts by weight.

The microcapsule ink containing a color-forming agent for pressure-sensitive copying prepared in this way is equipped with a dryer and an ultraviolet irradiator or only an ultraviolet irradiator without a dryer, flexographic printing, gravure printing and offset printing. ,
By letterpress printing, screen printing or the like, for example, by printing and coating on the back surface or front surface of a support such as paper, synthetic paper, film or the like or a receiving sheet having a receiving layer provided on the support, drying and ultraviolet irradiation or ultraviolet irradiation alone. It is used as an upper sheet, middle sheet, or self-coloring type pressure-sensitive copying sheet by curing the ink.

In the method of the present invention, the ink may be dried and cured by using a small dryer for hot air or infrared rays in combination with an ultraviolet irradiator, but only the ultraviolet irradiator may be used depending on the type and amount of the solvent used. But it's okay. In particular,
When alcohols are used as the volatile organic solvent as the ink medium in a compounding ratio of the volatile organic solvent as the ink medium with the ultraviolet-curable compound in the range of 80:20 to 20:80, only the ultraviolet irradiation device is used. It is easy to cure and is the most preferred embodiment of the present invention. Incidentally, the alcohols used when replacing the aqueous dispersion of microcapsules with the organic solvent dispersion in the ink formation step of the present invention may be recycled and reused to a certain extent in the actual industrial production scale. However, high purity alcohols are used as the ink medium.

The printing amount of the capsule ink is adjusted.
It is decided according to the type of ink
0.3-10 g / m by dry weight², Preferably 2-7 g
/ M ²It is a range of degrees.

As the electron-accepting developer of the receptor layer which develops a color by reacting with the above-mentioned electron-donating color former, the general ones described above which are conventionally known in the production of pressure-sensitive copying sheets are used. In the present invention, it is a substance that develops color by reacting with the color former encapsulated in the microcapsules.

The color developer is crushed by a ball mill, attritor, sand mill or the like, if necessary, and then an ordinary white pigment, a binder, and if necessary, a dispersant, a colored dye, a fluorescent whitening agent. , Various additives such as an ultraviolet absorber, an antioxidant and an antifoaming agent are added to prepare an aqueous coating liquid for forming a receiving layer.

Various kinds of white pigments can be used in the same manner as the substances added to the capsule ink coating layer.
As the binder, water-soluble natural polymer compounds such as proteins, starches, celluloses and saccharoses, polyvinyl alcohol, polyvinylpyrrolidone, sodium polyacrylate, polyacrylamide, maleic acid copolymer salt, butadiene-methacrylic acid are used. Water-soluble synthetic polymer compounds such as sodium salts of styrene-butadiene latex, acrylonitrile-butadiene latex, acrylic ester latex, vinyl acetate latex, methylmethacrylate-butadiene latex and their carboxy-modified (eg acrylic acid) ) There is a latex binder and the like.

The prepared receptive layer-forming coating liquid is an on-machine or off-machine according to 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. With coater, paper,
It is applied to various supports such as synthetic paper, film and the like.

The coating amount of the coating liquid for forming the receiving layer is appropriately determined depending on the kind of the prepared coating liquid and is not particularly limited, but generally 2 to 15 g / dry weight.
m ^{2 It is} preferably about 3 to 7 g / m ² .

[0038]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. The parts and% in the examples are parts by weight and% by weight, respectively, unless otherwise specified.

Example 1 [Preparation of lower sheet] As developer, 100 g of zinc 3,5-di (α-methylbenzyl) salicylate was added to 10 parts of toluene.
A toluene solution of the color developer was prepared by mixing and dissolving in 0 g at 70 ° C. Separately, 300 g of water containing 6 g of polyvinyl alcohol having a polymerization degree of 1,700 and a saponification degree of 98% is used as an internal volume of 1.00.
Place in a 0 ml stainless steel beaker T.S. K. The above toluene solution was added to this while stirring the homomixer at 3,000 rpm.

At the end of the addition of the toluene solution of the color developer, the number of revolutions was increased to 10,000 times / min and the mixture was stirred for 2 minutes, and then the stirring was stopped. The mixture was transferred to a hard glass three-necked flask having an inner volume of 1,000 ml. The flask was heated while slowly rotating the stirrer so that toluene and water were distilled from the distillation port. When this operation was continued at 100 ° C. for about 1 hour, the dispersion liquid contained almost no toluene. This was cooled to obtain an aqueous dispersion containing about 40% of the color developer. The average particle size of the resulting developer dispersed particles was 1.0 micron.

25 parts of the aqueous dispersion of the developer (solid content concentration 40%), 164 parts of 55% light calcium carbonate (trade name: Brilliant S-15, manufactured by Shiraishi Kogyo Co., Ltd.) and 50 parts of water were obtained. Mix and disperse and 1 as binder
0% polyvinyl alcohol (trade name: PVA-210,
A developer coating liquid was prepared by mixing 50 parts of an aqueous solution of Kuraray Co., Ltd., 16 parts of 48% SBR latex (trade name: SN-307, manufactured by Sumitomo Dow Co., Ltd.) and 150 parts of water. Next, the above-mentioned developer coating solution was applied to one side of a base paper of 40 g / m ^{2 in} a dry weight of 5
It was coated with an air knife coater so as to be g / m ² and dried to obtain a developed surface of a lower sheet for pressure-sensitive copying sheets.

[Preparation of Capsule] 8 parts of crystal violet lactone as a color former and alkyldiphenylethane (trade name: Hysol SA
S-296, manufactured by Nippon Petrochemical Co., Ltd.) was dissolved in 100 parts by heating to obtain a color developer-dissolved inner phase liquid. After adding 20% aqueous sodium hydroxide solution to 200 parts of a 3.0% aqueous solution of ethylene-maleic anhydride copolymer (trade name: EMA-31, manufactured by Monsanto Co.) to adjust the pH to 6.0, After emulsifying the internal phase liquid, the temperature of this system was raised to 55 ° 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 dropped into the emulsion and 0.1N-
Hydrochloric acid was added dropwise to adjust the pH to 5.3, and the mixture was warmed to 80 ° C, kept at that temperature for 1 hour, lowered to pH 3.5 with 0.2N-hydrochloric acid, kept warm for 3 hours, and then released. After cooling, an aqueous liquid in which capsules having an average particle size of 4.5 microns were dispersed was obtained.

Then, the aqueous liquid in which the capsules are dispersed is filtered, the organic solvent dispersion liquid is partially replaced with ethanol, and the capsules are washed and filtered with ethanol which is also used as an ink medium, and immediately after washing. Water was removed until the water content measured by the Karl Fischer method was 5% by weight or less based on the microcapsules, and cake-like capsules were obtained. At this time, the washing filtrate was washed to the extent that color stains were not generated. Then, the ethanol content of the cake-like capsule was adjusted so that the solid content concentration was 50%. The measured values of water content are summarized in Table 1.

[Preparation of Capsule Ink] Ethanol 20
To a solution obtained by adding 40 parts of ethyl cellulose (trade name: N-4, manufactured by Hercules Co., Ltd.) to 0 parts, 165 parts of pentaerythritol triacrylate and 5 parts of benzoin were added, and the above-mentioned capsule (containing 50% of ethanol) was added. ) 20
0 part was dispersed to obtain a capsule ink.

[Preparation of Medium-Use Sheet] After the flexographic printing of the capsule ink on the back surface of the color-developing surface of the lower-use sheet prepared above, the ink is cured only by an ultraviolet irradiation device,
An intermediate sheet for pressure-sensitive copying sheet was obtained by spot printing with an ink amount of 4.0 g / m ² . In addition, the obtained printed matter,
The opacity of the printed area was also good. In addition, 100m /
Even when printing was performed at a speed of min, the guide roll was not stained at all.

Example 2 Partial organic solvent substitution and washing and filtration with a volatile organic solvent used as an ink medium, except that ethanol containing 15% isopropyl alcohol was used as the volatile organic solvent as an ink medium instead of ethanol. The capsule ink was prepared in the same manner as in Example 1 to prepare a pressure-sensitive copy sheet intermediate sheet, and in the same manner as in Example 1 to obtain a printed matter. The state of the printed matter was the same as in Example 1.

Comparative Example 1 In the same manner as in Example 1, except that a capsule ink was prepared by using a capsule in which the aqueous liquid in which the capsule was dispersed was only partially replaced with the organic solvent dispersion liquid in the preparation of the capsule of Example 1. To produce an intermediate sheet for pressure-sensitive copy sheets.

Example 3 Example 1 was repeated except that 100 parts of benzyltoluene (trade name: Barrel Therm 430, manufactured by Matsumura Oil Co., Ltd.) was used as the oil for the internal phase in the preparation of the capsules instead of 100 parts of alkyldiphenylethane. Similarly, an intermediate sheet for pressure-sensitive copy sheet was prepared. The printed matter is in the first embodiment.
Was similar to.

Comparative Example 2 In the same manner as in Example 1, except that the capsule ink of Example 3 was prepared, except that the aqueous liquid in which the capsule was dispersed was replaced with an organic solvent dispersion liquid. An intermediate sheet for a pressure-sensitive copy sheet was prepared.

Example 4 4 parts of crystal violet lactone was added to 100 parts of alkylnaphthalene (trade name: KMC113, manufactured by Kureha Chemical Co., Ltd.).
Parts, and the resulting solution was adjusted to 70 ° C., and then a methoxymethylolmelamine melamine initial condensate (trade name: Cymel 350, manufactured by Mitsui Cyanamid Co., Ltd.) containing hexamethoxyhexamethylolmelamine as a main component was used as a solid content. Then, 62 parts were added and mixed to obtain an internal phase liquid.

Separately, an ethylene-maleic anhydride copolymer (trade name: EMA-) was placed in a stirring and mixing vessel equipped with a heating device.
31, manufactured by Monsanto Co., Ltd.) and 0.3 parts of ethylene-maleic anhydride polymer copolymer (trade name: EMA-81, manufactured by Monsanto Co.) were heated and dissolved in 300 parts of water to prepare an aqueous solution. Was added, and the pH was adjusted to 4.0 by adding a 5% aqueous sodium hydroxide solution.
Parts to make an aqueous medium for capsule production. This aqueous medium was heated to 85 ° C., and the internal phase liquid was emulsified and dispersed therein so that the average particle size became 4.5 μm.
The reaction was carried out at ℃ for 3 hours. Subsequently, the system was stirred for 0.
The pH of the system was adjusted to 3.2 by gradually adding 1N-hydrochloric acid, the system temperature was further raised to 95 ° C., and the mixture was reacted at 95 ° C. for 5 hours to obtain a milky white capsule dispersion liquid. . A pressure-sensitive copy sheet intermediate sheet was prepared in the same manner as in Example 1 except that this capsule dispersion liquid was used.

Comparative Example 3 In the same manner as in Example 1, except that a capsule ink was prepared by using a capsule in which the aqueous liquid in which the capsule was dispersed was replaced with an organic solvent dispersion liquid. An intermediate sheet for a pressure-sensitive copy sheet was prepared.

The moisture content of the inked cake capsules used in Examples and Comparative Examples and the color stain of the obtained pressure-sensitive copying sheets were evaluated. This is shown in Table 1.

[Measurement of Water Content by Karl Fischer Method] A method used as a standard in the field of chemistry, in which iodine reacts with water in the presence of sulfur dioxide to form hydriodic acid and sulfuric acid, The water content was measured by using the Karl Fischer reagent and Karl Fischer titrator.

[Evaluation of Coloring Property] A slip was prepared by using two sheets of each of the pressure-sensitive copying sheet intermediate sheets prepared in Examples and Comparative Examples as one set, and an electric typewriter (product name: el
Electric 65, manufactured by OLYMPIA) Impact strength When printed with high pressure, a good color image was obtained. (Evaluation Criteria) O: A good color image was obtained.

[Evaluation of Colored Stain during Production of Pressure Sensitive Copy Sheet]
In the color development evaluation after printing of the intermediate sheets for pressure-sensitive copy sheets prepared in Examples and Comparative Examples, the color stains developed on the developing surface were visually evaluated, and the color stains during the production of the pressure-sensitive copy sheet were evaluated. Is shown in Table 1. (Evaluation Criteria) ○: Good, Δ: Inferior, ×: Not practical.

[Evaluation of Colored Stain During Long-Term Storage] One medium-use sheet for pressure-sensitive copying sheets prepared in Examples and Comparative Examples was used.
After processing for 5 hours in a dryer at 15 ° C., the color development was evaluated, and the color stain developed on the color development surface was visually evaluated, and this is shown in Table 1 as the color stain during long-term storage of the pressure-sensitive copy sheet. . (Evaluation Criteria) ○: Good, Δ: Inferior, ×: Not practical.

[0059]

[Table 1]

[0060]

As is clear from the results shown in Table 1, the production method of the present invention can produce an ink efficiently, and the capsule ink for pressure-sensitive copying obtained in Examples by the production method of the present invention can be produced. The pressure-sensitive copy sheet thus obtained had a sufficient function as a pressure-sensitive copy sheet and had no color stain during the production of the pressure-sensitive copy sheet and during long-term storage.

Claims (3)

[Claims] 1. A microcapsule containing an electron-donating color former, (b) a volatile organic solvent as an ink medium, (c) an adhesive, (d) an ultraviolet-curable compound, (e).
In the method for producing a pressure-sensitive copying capsule ink containing a photopolymerization initiator as a basic component, an aqueous dispersion of microcapsules containing an electron-donating color former is replaced with an organic solvent dispersion, and then as an ink medium. A capsule ink for pressure-sensitive copying, which is characterized by being washed with a volatile organic solvent and using a cake-like capsule having a water content immediately after washing of not more than 5% by weight based on the microcapsule. Production method. 2. A method for producing a capsule ink for pressure-sensitive copying according to claim 1, wherein the volatile organic solvent as an ink medium is an alcohol. 3. The method for producing a capsule ink for pressure-sensitive copying according to claim 1, wherein the compounding ratio of the volatile organic solvent as an ink medium and the ultraviolet-curing compound is in the range of 80:20 to 20:80.