JPS59196732A - Preparation of microcapsule - Google Patents

Abstract

PURPOSE:To improve the holdability of a capsule core substance, by containing amines or phenols in water or a hydrophilic medium. CONSTITUTION:In polymerizing an aldehyde resin precondensate having a hydrophobic core substance allowed to be contained therein, amines or phenols such as urea or resorcinol are contained in water of a hydrophilic medium. As the aldehyde resin precondensate, a phenol/formaldehyde resin precondensate or an aminoaldehyde resin precondensate is designated and a polycondensation condition is set so as to hold a temp. to 70 deg.C or more and pH to 5.0. In addition, in order to easily perform emulsification, as an emulsifier, an anionic, a nonionic, a cationic and an amphoteric high-molecular or low-molecular emulsifiler can be used.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel method for producing microcapsules containing a hydrophobic core material, and in particular, a method for producing capsules with excellent retention of a capsule core material extremely easily and stably. It concerns how it can be done.

In recent years, microencapsulation technology has made remarkable progress, and the fields of use of these microencapsulated products are extremely wide and diverse, including pressure-sensitive copying paper.

Various methods are known for producing microcapsules, such as the coacelhesion method, interfacial polymerization method, and 1n-situ polymerization method.Among them, microcapsules having an aldehyde polycondensation resin as a wall film are water resistant, Due to its excellent solvent resistance, various encapsulation methods have been proposed. Patent No. 3016308, Special Publication No. 1977-
No. 51714, JP-A-48-57892, JP-A-51
-9079, JP-A-52-66878, JP-A-53
-84881, JP-A-53-84882, JP-A-5
3-84883, JP 54-25277, JP 54-49984, JP 54-53679, JP 54-85184, JP 54-'85185,
JP-A-54-107881, JP-A-55-8856, JP-A-55-15660, JP-A-55-47139
No., JP-A-55-51431, JP-A-55-6732
No. 9, JP-A-55-92'135, JP-A-55-13
No. 2631, JP-A-55-152546, JP-A-56
-51238, JP-A-56-78626, JP-A-5
6-102934, JP 56-115634, JP 56-155636, JP 5'l-11033
No. 2, JP-A-57-135038, JP-A-5) 147
No. 429, etc.

However, even though a large number of encapsulation methods have been developed and proposed, there is still a need for improvement because these methods are associated with one of the following disadvantages.

■ The physical properties of the water-soluble polymer used as an emulsifier for the core substance, such as the degree of polymerization, molecular weight distribution, copolymerization ratio, degree of modification, etc., are easily affected by subtle changes, and this is difficult to achieve on an industrial scale using materials from different lots. Variations in quality such as film strength are likely to occur during preparation.

■ Subtle differences in capsule preparation conditions can easily cause differences in the quality of capsules, so high-precision equipment is required to control this for industrialization.

■ The process is complicated.

■ In order to prevent capsule particle agglomeration during film formation, strong stirring is required to maintain a constant yield, and if the hydrophobic core substance has the property of being easily sheared with low stirring, encapsulation may be performed while maintaining the emulsified particle size. difficult to do.

(2) If the emulsifier used has poor emulsification stability, giant oil droplets are likely to form, which causes spot stains when applied to pressure-sensitive copying paper.

■ The system tends to thicken during film formation, and the film material has a weak tendency to deposit on the surface of the core substance, so it is necessary to use a large amount of water to promote the deposition, and high concentration paints I can't get it.

(2) The deposition efficiency of the film agent on the surface of the core material is poor, making it impossible to obtain sufficient inclusion retention properties.

(2) If the membrane material deposited on the surface of the core substance is in the form of a mixture of an aldehyde polycondensation resin having water resistance and a polymer compound having poor water resistance, only capsules with poor water resistance can be obtained.

Specifically, for example, JP-A-51-9079
No., JP-A-53-84882, JP-A-53-8488
No. 3, JP-A-54-53679 and JP-A-Sho 54-85
No. 184, JP-A-53-84881, and JP-A-54-
The method of forming a urea formaldehyde resin film or a melamine formaldehyde resin film in a hydrophobic heptamer unit and maleic anhydride or polyacrylic acid as shown in No. 49984 is accompanied by the drawbacks (1), (2), and (2) above. Also, JP-A-54-85185, JP-A-54-10788
carboxy-modified polyvinyl alcohol, gum arabic, as shown in No. 1 and JP-A-55-132631;
A method for forming a urea formaldehyde resin film in polyvinyl alcohol with a degree of saponification of 95% or higher, and JP-A-55-9
The method of forming an aminoaldehyde resin film in anion-modified polyvinyl alcohol or cation-modified polyvinyl alcohol, as shown in No. 2135 and JP-A No. 57-110332, has the following drawbacks: 1, 2, 2, 2, and 2. .

On the other hand, a method has also been proposed in which a hydrophobic core material contains an aldehyde polycondensation resin material, and after emulsification, polycondensation is performed to form a capsule membrane.
Examples thereof include Japanese Patent Publication No. 4-27257, Japanese Patent Publication No. 45-20885, and Japanese Patent Publication No. 52-18671.

These encapsulation methods rarely suffer from the drawbacks (1) to (3) mentioned above, but compared to capsules obtained by polymerizing and depositing a membrane material from water or a hydrophilic medium, the inclusions are The retention properties were quite poor, and the microcapsules were completely impractical as microcapsules for pressure-sensitive copying paper, which particularly requires good retention properties.

In view of the current situation, the present inventors have made efforts to develop a method for easily and stably producing capsules with excellent retention of capsule core substances in a method for producing microcapsules having an aldehyde polycondensation resin as a wall film. As a result of research, we found that in the encapsulation method, in which an initial condensate of aldehyde resin contained in a hydrophobic core material is polymerized and the resin is deposited on the surface of the hydrophobic core material fine particles, amines and The present inventors have discovered that microcapsules having extremely excellent retention of inclusions can be obtained by containing phenols and/or phenols, and have achieved the present invention.

The present invention is a microencapsulation method in which a hydrophobic core material containing a hydrophobic aldehyde resin initial condensate is emulsified in water or a hydrophilic medium to form a capsule membrane under conditions that promote polycondensation. Alternatively, it is a method for producing microcapsules characterized by containing amines and/or phenols in a hydrophilic medium.

Examples of the hydrophobic aldehyde resin initial condensate used in the present invention include a phenol formaldehyde resin initial condensate, an aminoaldehyde resin initial condensate, and the like. Examples of the phenol-formaldehyde resin initial condensate include initial condensates obtained by condensing formaldehyde with at least one type of phenol such as phenol, cresol, xylenol, redulcinol, hydroquinone, pyrocatechol, and pyrogallol. As the aminoaldehyde resin initial condensate,
For example, urea, thiourea, alkyl urea, ethylene urea,
At least one amine such as acetoguanamine, henzoguanamine, melamine, guanidine, dicyandiamide, biuret, cyanamide, etc. and at least one of formaldehyde, acetaldehyde, paraformaldehyde, hexamethylene 1-lamin, geltaraldehyde, glyoxal, furfural, etc. Among the initial condensate obtained by condensing one type of aldehyde, an alkylated product thereof, a partially alkylated product thereof, and an anion, cation, or nonionic modified product thereof, hydrophobic ones are used alone or in combination. Although the alkyl group used for etherification is not limited to these, those having 1 to 8 carbon atoms are preferred from the viewpoint of ease of preparation.

Examples of anionic modifiers include sulfamic acid, sulfanilic acid, glycolic acid, glycine, acidic sulfites, phenol sulfonate, and taurine, and examples of cationic modifiers include diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and dimethylamino. Nonionic modifiers such as ethanol include ethylene glycol, diethylene glycol, etc., and these are used to the extent that the initial condensate does not lose its hydrophobicity. As the initial condensate according to the present invention, as long as it is hydrophobic, various products such as those mentioned above can be used, but among them, the alkyl (l[, urea-melamine-formaldehyde initial Alkylated products of condensates are preferred in that extremely dense films can be obtained, and among these, butylated products of melamine-formaldehyde initial condensates are preferred, with an average degree of methylolation of 2.0 to 4.2.
Particularly preferred are those having a molar butylation degree of 10 to 50%.

In addition, when these aldehyde-based resin initial condensates are dissolved in a hydrophobic core material, if the initial condensate used has insufficient solubility or has a high viscosity, or if the hydrophobic core material in which the initial condensate is dissolved is When the viscosity is high, it is possible to use a polar solvent or a low boiling point solvent in combination. Examples of low boiling point solvents used for this include n-pentane, methylene chloride, ethylene chloride, carbon disulfide, acetone, methyl acetate, and chloroform. , methyl alcohol, tetrahydrofuran, n-hexane, carbon tetrachloride, ethyl acetate, ethyl alcohol, n-propyl alcohol, 1
so-propyl alcohol, n-butyl alcohol,
1so-butyl alcohol, t-butyl alcohol, n
-Pentyl alcohol, methyl ethyl ketone, Hensen, toluene, xylene, ethyl ether and petroleum ether, etc.

As the polar solvent, dioxane, cyclohexanone, methyl isobutyl ketone, dimethyl formamide, etc. are used.

Further, in the present invention, it is preferable that the hydrophobic initial condensate is used dissolved in the hydrophobic core material, but it can also be used in a dispersed state.

The amount of the hydrophobic aldehyde resin initial condensate is as follows:
-JIM
Although it cannot be determined, 2 g (in terms of amino compound or phenol compound) per 100 parts of hydrophobic core (hereinafter, preferably 50 parts by weight or less, particularly 4 parts by weight or more and 30 parts by weight) The following is more preferable.

In addition, when the hydrophobic core substance used is a solid, this solid is dispersed in the initial condensate or a low boiling point solvent in which the initial condensate is dissolved, and then used in the form of emulsification in water or a hydrophilic medium. It will be done.

In the present invention, the amines and phenols to be contained in water or a hydrophilic medium include primary or secondary monovalent or polyvalent amines and two sites having no substituents at the ortho or para positions relative to the phenolic hydroxyl group. The phenols having the above-mentioned properties are mentioned, and among these, preferred are amines and phenols used to form a hydrophobic aldehyde resin initial condensate. Among them, urea and resorcinol are particularly preferable because they have good properties.The amines and phenols mentioned above may be used alone or in combination.

Note that the amount of amines and phenols added to water or a hydrophilic medium varies depending on the type of initial condensate and its degree of condensation, etc., and cannot be determined unconditionally. It is preferable to add 0.2 mol or more and 20 mol or less, and 1 mol or more and 1 mol or more.
It is more preferable to add 0 mol or less.

Furthermore, the amines or phenols may be added at any time before the completion of the reaction, but in terms of effectiveness,
Addition immediately after emulsification is most significant.

The polycondensation conditions in the present invention depend on the type and degree of condensation of the aldehyde resin initial condensate used, the degree of alkylation, or
This may vary depending on the intended use of the capsule, etc., but cannot be determined in general, but preferably under conditions of 70°C or lower or P
It is preferable to maintain the temperature for 1 hour or more under conditions of H5.0 or less and 60°C or more, more preferably 80°C or more, or PH4.5 or less and 70°C or more, especially 3.
It is preferable to maintain the temperature for more than an hour.

In the present invention, it is not necessary to use an emulsifier as long as the hydrophobic core material containing the oil-soluble aldehyde resin initial condensate can be emulsified in water or a hydrophilic medium. It is preferable to use the emulsifier, and anionic, nonionic, cationic, or amphoteric polymer or low-molecular emulsifiers can be used.

As the anionic polymer, both natural and synthetic polymers can be used, such as -COO-.

Examples include those having SO3+ OPO knee group, etc.
Specifically, natural polymers such as gum arabic, carrageenan, sodium alginate, pectic acid, gum tragacanth, almond gum, and agar, carboxymethyl cellulose,
Sulfated cellulose, sulfated methyl cellulose, carboxymethyl pine, phosphorylated starch, semi-synthetic polymers such as ligninsulfonic acid, maleic anhydride (including hydrolyzed) copolymers, acrylic acid, meccrylic acid Alternatively, crotonic acid-based polymers and copolymers, vinylhensensulfonic acid-based or 2-acrylamido-2-methyl-propanesulfonic acid-based polymers and copolymers, and portion 7 of such polymers and copolymers. Examples include synthetic polymers such as mido or partially esterified products, carboxy-modified polyvinyl alcohol, sulfonic acid-modified polyvinyl alcohol, and phosphoric acid-modified polyvinyl alcohol.

More specifically, maleic anhydride-based (including hydrolyzed) copolymers include methyl vinyl ether-maleic anhydride copolymer, ethylene, maleic anhydride copolymer, and vinyl acetate-maleic anhydride copolymer. Examples include methacrylamide-maleic anhydride copolymer, isobutylene-maleic anhydride copolymer, and the like.

Examples of the acrylic acid copolymer, methacrylic acid copolymer, or crotonic acid copolymer include methyl acrylate-acrylic acid copolymer (hereinafter referred to as "copolymer"), 7-ethyl acrylate-acrylic acid, methyl acrylate-methacrylic acid, methyl methacrylate-acrylic acid, methyl methacrylate-methacrylic acid, methyl acrylate-acrylamide-acrylic acid, acrylonitrile-acrylic/linoacid, -? Chrylonitrile-methacrylic acid, methyl ethyl acrylate-acrylic acid, hydroxyethyl meccrylate-methacrylic acid, vinylacetate-vinyl acrylic acid, vinyl acetate-methacrylic acid, acrylamide-acrylic acid, acrylamide-methacrylic acid, methacrylamide-acrylic acid acid, methacrylamide-methacrylic acid,
Examples include copolymers such as vinyl acetate-crotonic acid.

Examples of vinylhensensulfonic acid-based or 2-acrylamide-2-methyl-propanesulfonic acid-based copolymers include methyl acrylate-vinylhensensulfonic acid (or salt thereof) copolymer, vinyl acetate-vinylhensenes Sulfonic acid copolymer, acrylamide-vinylbenzenesulfonic acid copolymer, acryloylmorpholine-vinylbenzenesulfonic acid copolymer, vinylpyrrolidone-vinylbenzenesulfonic acid copolymer, vinylpyrrolidone-2-acrylamide-2-methyl-propane Examples include sulfonic acid copolymers.

As the nonionic polymer, both natural and synthetic polymers can be used, and examples thereof include those having an -OH group.

Specific nonionic semi-synthetic polymers include hydroxyethylcellulose, methylcellulose, and pullulan ('
Examples include non-crystalline, easily water-soluble polymeric polysaccharides made by microbial fermentation using flour as a raw material, soluble starches, and oxidized starches.

Further, as a synthetic product, polyvinyl alcohol can be mentioned.

Examples of cationic polymers include cation-modified polyvinyl alcohol, and examples of amphoteric polymers include gelatin.

Anionic and cationic low-molecular emulsifiers.

We can list sexual, nonionic, and amphoteric ones, but
Among them, anionic ones are preferable, and among them, organic sulfuric acid or organic phosphoric acid salts having a total carbon number of 1 to 14 are preferable, and specifically, vinyl sulfone is preferable. sodium acid, sodium hensensulfonate, sodium benzenesulfinate, sodium p-1-luenesulfonate, p-
Sodium toluenesulfinate, sodium p-vinylhensenesulfonate, sodium p-1-amylhensenesulfonate, sodium naphthalene-α-sulfonate, sodium naphthalene-β-sulfonate, 2-methylnaphthalene-6 -Sodium sulfonate, 2.6-dimethylnaphthalene-8-sodium sulfonate, 2゜6-
Sodium dimethylnaphthalene-3-sulfonate, 1-
Sodium naphthol-4-sulfonate, Hensen-m
Examples include sodium lithium-disulfonate, sodium diphenyl phosphate, sodium phenylposboxate, sodium lithium di-n-butyl phosphate, and sodium di-1-amyl phosphate.

In the present invention, the above-mentioned high-molecular or low-molecular emulsifiers may be used alone or in combination, but preferred among these are high-molecular emulsifiers, among which anionic polymers are preferred, especially Artech F-based resins. A maleic anhydride-based copolymer having no hydroxyl or amide groups, which undergoes almost no crosslinking reaction with the initial condensate and has excellent emulsifying power;
Polymers belonging to acrylic acid-based, meccrylic acid-based, or crotonic acid-based polymers and copolymers hardly cause the thickening that tends to occur in steel products under severe conditions such as those used in the present invention, and emulsification. This is preferable because the particles are easily stabilized. Among these, ethylene-maleic anhydride copolymer is particularly preferred.

In addition, the emulsifier as mentioned above is added in water or a hydrophilic medium at a concentration of 0.5
It is preferable to contain % or more, and it is easy to prepare an emulsion.
From the viewpoint of stabilizing the emulsion, the content is more preferably 2% or more. The upper limit of the amount used is determined by the viscosity of the system, the capsule preparation device, etc., but is generally kept at 20% or less.

In the present invention, so-called acid catalysts commonly used in the field of aminoaldehyde resin production, such as formic acid, acetic acid, citric acid, Sierra acid, p-toluenesulfonic acid, hydrochloric acid, and sulfuric acid, are used to maintain the reaction system acidic. .

In the present invention, the hydrophobic core substance to be encapsulated in the microcapsules is not particularly limited, but the following substances are exemplified.

Animal oils such as fish oil, lard oil, vegetable oils such as olive oil, peanut oil, linseed oil, soybean oil, Himashiura oil, petroleum, mineral oils such as kerosene, xylene, toluene, etc., alkyl-substituted diphenylalkanes, Alkyl-substituted naphthalene, biphenylethane, methyl salicylate, diethyl adipate, di-n-propyl adipate,
Synthetic oils such as di-n-butyl adipate, di-methyl phthalate, diethyl phthalate, di-n-propyl phthalate, di-n-butyl phthalate, di-n-octyl phthalate, etc. A solution in which an electron-donating color former, an electron-accepting color developer, a ligand compound, an organic metal salt, etc. are dissolved in a water-insoluble or substantially water-insoluble liquid or the above-mentioned synthetic oil;
Water-insoluble metal oxides and salts, fibrous materials such as cellulose or asbestos, water-insoluble synthetic polymeric materials, minerals, pigments, glasses, fragrances, flavors, fungicidal compositions, Physiological compositions, fertilizer compositions.

In order to more specifically explain the method of the present invention, examples will be described below in which the method is applied to the field of pressure-sensitive copying paper, but the present invention is of course not limited thereto. Further, unless otherwise specified, parts and % in the examples represent parts by weight and % by weight, respectively.

Example 1 A melamine-formaldehyde resin initial condensate (trade name Nikaratsuku) was added to a solution obtained by dissolving 20 parts of lauryl gallate in a mixed solution of 50 parts of di-ethyl adipate and 50 parts of di-n-butyl adipate. MS-111 (manufactured by Nippon Karhide Kogyo Co., Ltd.) was added and mixed in a solid content of 27 parts to obtain an internal phase liquid.

Separately, 200 parts of a 3.0% aqueous solution of ethylene-maleic anhydride copolymer (trade name EMA-31, manufactured by Monsanto) was added to a stirring mixing container equipped with a heating device, and 200 parts
% caustic soda aqueous solution was added to adjust the pH to 5.5 to obtain an aqueous medium for capsule production. After the internal phase liquid was emulsified and dispersed in this aqueous medium so that the average particle size was 5.0 μm, the temperature of this system was raised to 60°C.

Next, 15 parts of urea was added to this system with stirring, and an additional 0.5 parts of urea was added to the system with stirring.
The pH of the system was adjusted to 3°8 by gradually adding N-hydrochloric acid, and then the temperature of the system was gradually raised to 80°C, and then further raised to 80°C.
The mixture was reacted at 0° C. for 5 hours to obtain a milky white capsule dispersion.

Add and mix 20 parts of wheat starch powder and 10 parts of pulp powder to the obtained capsule dispersion, add water to make the solid content concentration 25% to make a capsule coating liquid, and apply it to 40 g/rd paper using an air knife coater. The paper was smeared to a solid content of 5 g/rf to obtain a top paper.

Preparation of the bottom paper 89 parts of t-butylbenzoic acid, 125 parts of diphenyl phosphate, and 70 parts of sodium laurylbenzenesulfonate were added to 800 parts of a 5% aqueous solution of caustic soda, and the resulting aqueous solution was cleaved.
An aqueous solution of 108 parts of ferric chloride dissolved in 500 parts of water was added under strong stirring to form yellow fine particles, and then a 20% aqueous solution of sodium monobutylbenzoate was added to this dispersion.

0 parts of Ti and then added Ti to this dispersion under vigorous stirring.
125 parts of C was gradually added to form a pale yellow fine particle dispersion, which was filtered and washed to obtain a slurry.

Next, 1 part of sodium polyacrylate and 1 part of hydroquine ethylcellulose were dissolved in 200 parts of water, and 20 parts of the above slurry in terms of solid content, 40 parts of titanium oxide, and 40 parts of calcium carbonate were added thereto and strongly dispersed. , carboxy-modified styrene-butadiene copolymer latex (
A coating liquid was obtained by adding 15 parts of 50% solid content.

The resulting coating liquid was applied to 40 g/rl paper at a dry weight of 5
g/n (g/n) using a rod blade coater to obtain a lower paper.

Evaluation When the upper paper and lower paper prepared as described above were overlapped and printed using a typewriter, a clear colored image was obtained. Separately, after processing the top paper for 12 hours under humidified conditions at 50°C and 190%, when printing on a typewriter over the bottom paper, a clear colored image was obtained that was exactly the same as when using the untreated top paper. It was found that the material had good core material retention.

Comparative Example 1 Example 1 except that the emulsified dispersion was prepared without adding urea.
Capsules were prepared and clay paper was made in exactly the same manner as above.

Next, the same evaluation as in Example 1 was performed using the lower paper prepared in the same manner as in Example 1. When the untreated upper paper was used, a clear colored image was obtained;
In evaluation after treatment under humidified conditions at 190% °C, a considerable decrease in color density was observed, and it was found that core substance retention was poor.

Examples 2 and 3 10 parts of resorcinol instead of 15 parts of urea in the emulsified dispersion
Capsules were prepared in exactly the same manner as in Example 1, except that 20 parts of urea and 2 parts of resorcinol were added, and a top paper was made. Next, the same evaluation as in Example 1 was performed using the bottom paper prepared in the same manner as in Example 1.
Both capsules were found to have good core material retention.

Patent Applicant Kanzaki Paper Co., Ltd. Procedural Amendment May 31, 1980 Patent Application No. 62418 of 1981 Process for Manufacturing Microcapsules 3, Person Making Amendment Representative Fukuo Endo 4, Agent Residence (〒 660) Kanzaki Paper Co., Ltd., 1-11, Jokoji Motomachi, Amagasaki City (Contents of amendment) (1) The scope of the claims is amended as follows.

(Note) In a microencapsulation method in which a hydrophobic core material containing an mR aldehyde resin initial condensate is emulsified in water or a hydrophilic medium and a capsule membrane is formed under conditions that promote polycondensation. A method for producing microcapsules, which comprises containing amines and/or phenols in water or a hydrophilic medium.

(2) The production method according to claim (1), wherein the aldehyde resin initial condensate is an alkylated product of an initial condensate of an amine compound and formaldehyde.

(3) The production method according to claim (1), wherein the aldehyde resin initial condensate is a melamine-formaldehyde resin initial condensate, a urea-melamine-formaldehyde resin initial condensate, or a urea-formaldehyde resin initial condensate.

(4) The manufacturing method according to items (1) to (2) above, wherein the polycondensation is carried out at a pH of 5.0 or lower, at a temperature of 60°C or higher, or at a temperature of 70°C or higher for 3 hours or more.

(i) Water or a hydrophilic medium is a maleic anhydride copolymer,
The manufacturing method according to any one of claims 1 to 3, which contains at least one type of water-soluble polymer belonging to the group of acrylic acid-based, methacrylic acid-based, or crotonic acid-based polymers and copolymers.

(2) Page 8, lines 5 and 12 of the specification, page 9, line 13,
``Hydrophobicity...'' in lines 4 to 5 and 6 on page 10, line 17 on page 11, and line 14 on page 12.
...Oil-soluble..." is corrected.

(3) After correcting [...preferred,] on line 11 of page 10 of the specification to "...preferable.", change from "among them..." to "..." on line 14 of the same page. ·preferable.

' Delete up to '.

(4) Lines 14 to 16 of page 11 of the specification are amended to the following explanation.

(Note) In the present invention, it is desirable that the oil-soluble initial condensate is used in a completely dissolved state in the hydrophobic core material, but it can also be used in a partially dissolved state.

(5) After “polymer” on page 15, line 13 of the specification, “,
``Styrene-maleic anhydride copolymer'' is replenished.

(6) The following Example 4 and Comparative Example 2 are added after Example 2.3 on page 24 of the specification.

(Note) Example 4 4 parts of crystal high oleso lactone was mixed with 100 parts of alkylnaphthalene (trade name: KMC Oil, manufactured by Kureno Kagaku Co., Ltd.)
An internal phase liquid was obtained by mixing and dissolving 100 parts of n-butyl alcohol and 45 parts of jetoxydimethylol urea in a solution at 80° C. obtained by dissolving 100 parts of n-butyl alcohol and 45 parts of jetoxydimethylol urea.

Separately, 1000 parts of a 3.0% aqueous solution of a conytylene-maleic anhydride copolymer (trade name EMA~31. manufactured by Monsanto) was added to a stirring mixing vessel equipped with a heating device, and a 20% aqueous solution of caustic soda was added thereto. After adjusting P to 4.5, 6 parts of resorcin was further added and dissolved, and the liquid temperature was raised to 70°C to prepare an aqueous medium for capsule production. After emulsifying and dispersing the yarn to a diameter of 5.0 μm, the yarn was heated to 85° C. and reacted at this temperature for 2 hours.

Next, 200 parts of IN-hydrochloric acid was gradually added to this system with stirring, and then the temperature of the system was raised to 95°C, and then further heated to 95°C.
The reaction was carried out at °C for 5 hours to obtain a pale blue capsule dispersion.

To the resulting capsule dispersion, 20 parts of wheat starch powder and 10 parts of pulp powder were added and mixed, and water was added to make the solid content concentration 25% to make a capsule coating liquid. The upper paper was obtained by smearing to a solid content of 3 g/n.

Preparation of bottom paper 65 parts of aluminum hydroxide, 20 parts of zinc oxide, 3.5-
Mixture of zinc di(α-methylhensyl)salicylate and α-methylstyrene/styrene copolymer (melt ratio 80/
20) Add 20 parts of carboxy-modified styrene-butadiene copolymer latex (solid content) to a dispersion obtained by milling 15 parts of aqueous polyhinyl alcohol solution (solid content) and 300 parts of water in a ball mill for 24 hours. ) was added to HUM, and a developer coating solution was smeared on 40 g of 1rd paper with an air knife caulk to give a solid content of 5 g/n (.

When the upper paper and lower paper prepared as described above were overlapped and printed using a typewriter, a clear colored image was obtained. Separately, after processing the top paper for 12 hours at 50°C and 90% humidity, when printed on a typewriter over the bottom paper, the colored image was just as clear as when using the untreated top paper. was obtained, and it was found that it had good core substance retention.

Comparative Example 2 Capsules were prepared in exactly the same manner as in Example 4, except that resorcin was not added to the aqueous medium for capsule production.
I created the above paper. Next, the same evaluation as in Example 4 was carried out using the lower paper prepared in the same manner as in Example 4. When the untreated upper paper was used, a clear colored image was obtained; Evaluation after treatment under 90% humid conditions revealed that the color density was considerably reduced and the core material retention was poor.

(that's all) , -205-

Claims (6)

[Claims] (1) In a microencapsulation method in which a hydrophobic core material containing a hydrophobic aldehyde resin initial condensate is emulsified in water or a hydrophilic medium and a capsule membrane is formed under conditions that promote polycondensation, water Alternatively, a method for producing microcapsules, which comprises containing amines and/or phenols in a hydrophilic medium. (2) The production method according to claim (1), wherein the aldehyde resin initial condensate is an alkylated product of an initial condensate of an amino compound and formaldehyde. (3) The production method according to claim (1), wherein the aldehyde resin initial condensate is a melamine-formaldehyde resin initial condensate, a urea-melamine-formaldehyde resin initial condensate, or a urea-formaldehyde resin initial condensate. (4) The production method according to claim (1), wherein the aldehyde resin initial condensate is a butylated product of a melamine-formaldehyde initial condensate. (5) The manufacturing method according to items (1) to (4), wherein the polycondensation is carried out at a pH of 5.0 or lower, at a temperature of 60°C or higher, or at a temperature of 70°C or higher for 3 hours or more. (6) A claim in which water or a hydrophilic medium contains at least one water-soluble polymer belonging to the group of maleic anhydride-based copolymers, acrylic acid-based, methacrylic acid-based, or crotonic acid-based polymers and copolymers. The manufacturing method according to items (1) to (5).