JPS59230634A - Prepartion of microcapsule - Google Patents

Abstract

PURPOSE:To stably prepare a microcapsule excellent in the holdability of a capsule core substance, by a method wherein a hydrophobic substance containing an oil-soluble methylated methylol melamine precondensate is emulsified in water and, thereafter, polycondensation is promoted to from a wall membrane. CONSTITUTION:In a micro-encapsulating method wherein a hydrophobic substance containing a melamine-formaldehyde precondensate is emulsified in water or a hudrophilic medium and, thereafter, policondensation is promoted to form a wall membrane. As the aforementioned precondensate, an oil-soluble methylated methylol melamine precondensate is used. In addition, the aforementioned polycondensation is performed so that the obtained emulsion is maintained at 70 deg.C or more or under a condition of pH5.0 or less and 60 deg.C or more for 2hr or more. Furthermore, an anionic high-molecular substance having no hydroxyl group or amido group is contained in water or the hydrophilic medium. By this method, a microcapsule having a good core holding property can be obtained even by reaction under a mild condition.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing microcapsules containing a hydrophobic core material. In particular, it is an object of the present invention to provide a capsule manufacturing method that allows capsules with excellent core material retention properties to be manufactured extremely easily and has an extremely wide range of applicability.

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 coacervation, interfacial polymerization, and 1n-situ polymerization, but among them, microcapsules with aldehyde polycondensation resin as a wall film have excellent water resistance and resistance. Various encapsulation methods have been proposed due to its superior solvent properties, and for example, a US patent has been granted for a method in which an aldehyde polycondensation membrane material existing in water or a hydrophilic medium is deposited around a hydrophobic core substance. No. 3016308, Special Publication Showa 4'l
-51714, JP-A-48-5. -7892, JP 51-9079, JP 52-66878, JP 53-84881, JP 53-84882, JP 53-84883, JP 54-25277 issue,
JP-A-54-49984, JP-A-54-53679, JP-A-54-85184, JP-A-54-85185
No., JP-A-54-107881, JP-A-55-885
No. 6, JP-A-55-15660, JP-A-55-471
No. 39, JP-A-55-51431, JP-A-55-67
No. 329, JP-A-55-92135, JP-A-55-1
No. 32631, JP-A-55-152546, JP-A-5
6-51238, JP 56-78626, JP 56-102934, JP 56-115634,
JP-A-56-155636, JP-A-57-11033
No. 2, JP-A-57-135038, JP-A-57-14
No. 7429, 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 with different lofts. 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.

■ Strong stirring above a certain level is required to prevent capsule particle aggregation during film formation, and if the hydrophobic core material has the property of being easily sheared with low stirring, encapsulation may be performed while maintaining the emulsified particle size. It is difficult to do so.

(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.

■ During film formation, there is a tendency for the system to thicken, and the film material has a weak tendency to deposit on the surface of the core material, so it is necessary to use a large amount of water landing to promote the deposition. High concentration paint cannot be obtained.

(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, Japanese Patent Application Laid-Open No. 51-9079
No., JP-A-53-84882, JP-A-53-8488
No. 3, JP-A No. 54-53679 and JP-A No. 54-85
No. 184, JP-A-53-84881, and JP-A-54-
49984, and a urea formaldehyde resin film or a melamine formaldehyde resin H' in maleic anhydride or polyacrylic acid.
The At-forming method has the above-mentioned drawbacks (1), (2), and (2). Also, JP-A-54-85185, JP-A-54-1
A method of forming a urea formaldehyde resin film in carboxy-modified polyvinyl alcohol, gum arabic, polyvinyl alcohol with a degree of saponification of 95% or more as shown in JP-A-55-132631 and JP-A-55-92135. , anion-modified polyvinyl alcohol as shown in JP-A-5'1-1103'32;
The method of forming an aminoaldehyde resin film in cation-modified polyvinyl alcohol is accompanied by the above-mentioned drawbacks (1), (2), (2), (2), and (3).

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.

Although these encapsulation methods rarely have the disadvantages (1) to (3) mentioned above, they have better retention of inclusions compared to capsules obtained by polymerizing and depositing a membrane material from water or a hydrophilic medium. The microcapsules were quite poor in quality and were completely impractical as microcapsules for pressure-sensitive copying paper, which particularly requires good retention.

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, 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 fine particles of the hydrophobic core material, a specific initial condensate of aldehyde resin is used. The present inventors have discovered that microcapsules having good inclusion retention properties can be obtained even by reaction under mild conditions by selecting the following, 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. This is a method for producing microcapsules, characterized in that a hydrophobic methylated methylolmelamine initial condensate is used as the initial condensate.

In addition, the present inventors previously reported in Japanese Patent Application No. 58-54779 that microcapsules having extremely excellent inclusion retention properties can be obtained by polycondensing an aldehyde resin initial condensate under severe reaction conditions. However, the encapsulation method of the present invention allows encapsulation under much milder conditions than the reaction conditions, so it is useful when encapsulating substances that are somewhat unstable to heat and acids. However, it is also possible to obtain good capsules, and it can be said that this encapsulation method has a wider range of applications.

The hydrophobic methylated methylolmelamine initial condensate used in the present invention may be one that completely or partially dissolves in the hydrophobic core material, and its formaldehyde substitution degree and methylation may be adjusted as appropriate depending on the HLB of the core material. degree, the range of the average number of nuclei is adjusted. Although not limited to this, in that particularly good capsules can be obtained,
Preferably, the degree of formaldehyde substitution is from 85 to 100%, the degree of methylation is from 90 to 100%, and the average number of nuclei is from 1 to 1o.

Further, the degree of formaldehyde substitution in the present invention is a value indicating what percentage of the active hydrogens possessed by the amine groups of melamine are substituted by methylol groups, methoxymethylol groups, and methylene groups, and is expressed by the following formula.

0 Also, the degree of methylation is a value indicating what percentage of the methylol group is methoxylated, and is expressed by the following formula.

Moreover, the average number of nuclear bodies is the average number of melamine residues contained in one molecule of the initial condensate.

Furthermore, in the present invention, other aldehyde-based resin initial condensates can be used in combination with the above-mentioned methylated methylolmelamine initial condensate for the purpose of changing the patterning performance. Examples of the resin initial condensate include phenol formaldehyde resin initial condensate, 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 phenol such as phenol, cresol, xylenol, resorcinol, hydroquinone, pyrocatechol, and pyrogallol. The aminoaldehyde resin initial condensate includes at least one amine such as urea, thiourea, alkylurea, ethyleneurea, acetoguanamine, benzoguanamine, melamine, guanidine, dicyandiamide, biuret, and cyanamide, and formaldehyde, acetaldehyde, Initial condensate obtained by condensing at least one kind of aldehyde such as formaldehyde, hexamethylenetetramine, geltaraldehyde, Glioxal, furfural, etc., or an alkylated product thereof, a partially alkylated product thereof, and anion, cation, or nonion thereof. Among the modified products, hydrophobic ones are used alone or in combination. Although the alkyl group used for etherification is not limited to these, those having a carbon number of 1 to 8 are preferred from the viewpoint of ease of preparation.

Examples of anionic modifiers include sulfamic acid, sulfanilic acid, glycolic acid, glycine, acidic sulfite, phenol sulfonate, and clarine; 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. When these aldehyde-based resin initial condensates are dissolved in a hydrophobic core material, there are cases where the initial condensate used has insufficient solubility or high viscosity, or when the viscosity of the hydrophobic core material in which the initial condensate is dissolved is If the temperature is high, it is possible to use a polar solvent or a low boiling point solvent. Examples of low boiling point solvents used for this include n-pentane, methylene chloride, ethylene chloride, carbon dioxide, acetone, methyl acetate, chloroform, and methyl. Alcohol, tetrahydrofuran, n-hexane, carbon tetrachloride, ethyl acetate, ethyl alcohol, n-propyl alcohol, 1so-7"lopyl alcohol, n' butyl alcohol, 1so-butyl alcohol, mo-butyl alcohol, n-pentyl alcohol , methyl ethyl ketone, benzene, toluene, xylene, ethyl ether and petroleum ether.

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

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

The amount of the methylated methylolmelamine initial condensate varies depending on the hydrophobic core material used, the type and amount of other aldehyde resins used together, the particle size of the capsule, its intended use, etc. Although not determined, it is preferably 2 parts by weight or more and 50 parts by weight or less, particularly preferably 4 parts by weight or more and 30 parts by weight or less, in terms of amine compound or phenol compound, based on 100 parts by weight of the hydrophobic core material.

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.

The conditions for promoting polycondensation in the present invention vary depending on the type of methylated methylolmelamine initial condensate used and the intended use of the capsule, and are generally not determined, but are preferably at 40°C or higher for 1 hour or more, particularly preferably at 60°C. It is preferable to maintain the condition under the above conditions for 1 hour or more, especially 3 hours or more.
When using this as microcapsules for pressure-sensitive copying paper, the temperature is 70°C or higher or P I-I 5
．． It is preferable to maintain the temperature at 0°C or lower and 60°C or higher for 2 hours or more.

In the present invention, if the hydrophobic core material containing the methylated methylolmelamine initial condensate can be emulsified in water or a hydrophilic medium, it is not necessary to use an emulsifier, but an emulsifier is used to facilitate emulsification. This is preferred, and as the emulsifier, 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 -so;, -opo seven groups, etc.
Specifically, natural polymers such as gum arabic, carrageenan, sodium alginate, pectic acid, gum tragacanth, almond gum, and agar, carboxymethyl cellulose,
Semi-synthetic polymers such as sulfated cellulose, sulfated methylcellulose, carboxymethyl starch, phosphorylated starch, ligninsulfonic acid, maleic anhydride-based (including hydrolyzed) copolymers, acrylic acid-based, methacrylic acid-based, or Crotonic acid-based polymers and copolymers, vinylhenzenesulfonic acid-based or 2-acrylamido-2-methyl-propanesulfonic acid-based polymers and copolymers, and partial amides or copolymers of such polymers and copolymers. Examples include synthetic polymers such as 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 M copolymer, and the like.

Examples of acrylic acid copolymers, methacrylic acid copolymers, and crotonic acid copolymers include methyl acrylate-acrylic acid copolymers (hereinafter, the term ``copolymer'' is abbreviated); ethyl acrylate-acrylic acid; , methyl acrylate-methacrylic acid, methyl methacrylate-acrylic acid, methyl methacrylate-methacrylic acid, methyl acrylate-acrylamide-acrylic acid, acrylonitrile-acrylic acid,
Acrylic nitrile-methacrylic acid, hydroxyethyl acrylate-acrylic acid, hydroxyethyl meccrylate-methacrylic acid, vinyl acetate-acrylic acid, vinyl acetate-meccrylic acid, acrylamide-acrylic acid,
Examples include copolymers of acrylamide-methacrylic acid, methacrylamide-acrylic acid, methacrylamide-methacrylic acid, and vinyl acetate-crotonic acid.

Examples of vinylbenzenesulfonic acid-based or 2-acrylamido-2-methyl-propanesulfonic acid-based copolymers include methyl acrylate-vinylbenzenesulfonic acid (or salt thereof) copolymer, vinyl acetate-vinylbenzenesulfone M copolymer Polymer, acrylamide-vinylbenzenesulfonic acid copolymer, acryloylmorpholine-vinylbenzenesulfonic acid copolymer, vinylpyrrolidone-vinylbenzenesulfonic acid copolymer, vinylpyrrolidone-2-
Examples include acrylamide-2-methyl-propanesulfonic acid copolymer.

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 hydroxyethyl cellulose, methylcellulose, luulose, and pullulan (
FJ? 8 starch,
Examples include oxidized starch.

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.

Examples of low-molecular emulsifiers include anionic, cationic, nonionic, and amphoteric ones, but anionic ones are preferred, and among them, organic sulfuric acids having a total carbon number of 1 to 14 are preferred. Or organic phosphoric acid 1
, i'', Na''; NlI4+ salts are preferred, specifically sodium vinylsulfonate, sodium Hensensulfonate, sodium Hensensulfinate, p-
) Sodium p-1-ruenesulfonate, Sodium p-vinylbenzenesulfonate, Sodium p-1-amylbenzenesulfonate, Sodium naphthalene-β-sulfonate, Sodium naphthalene-β-sulfonate , 2-methylnaphthalene-6
-Sodium sulfonate, 2,6-dimethylnaphcrene-8-sodium sulfonate, 2゜6-dimethylnaphthalene-3-sodium sulfonate, 1-naphthol-
Examples include sodium 4-sulfonate, sodium benzene-m-disulfonate, sodium diphenyl phosphate, sodium phenylphosphonate, sodium di-n-butyl phosphate, sodium diamyl phosphate, and the like.

In the present invention, the above-mentioned polymeric or low-molecular emulsifiers may be used alone or in combination, but preferred among these are polymeric emulsifiers, and among these, anionic polymers are preferred, particularly methylated methylol melamine. Maleic anhydride-based copolymers, acrylic acid-based, methacrylamide, or chlorine-based copolymers that do not have hydroxyl or amine F groups, have almost no crosslinking reaction with the initial condensate, and have excellent emulsifying power.
Polymers belonging to henic acid-based polymers and copolymers have the following advantages: they hardly cause thickening, which tends to occur when they are prepared under severe conditions such as those used in the present invention, and emulsified particles are easily stabilized. Preferably. 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, oxalic acid, para-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, etc., vegetable oils such as olive oil, peanut oil, linseed oil, soybean oil, castor oil, etc., mineral oils such as petroleum, 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, dimethyl phthalate, diethyl phthalate, di-n-propyl phthalate, di-n-butyl phthalate, di-n-oc, tyl phthalate, etc. A water-insoluble or substantially water-insoluble liquid or a solution of an electron-donating color former, an electron-accepting color developer, a ligand compound, an organic metal salt, etc. dissolved in the above-mentioned synthetic oil, or a water-insoluble metal. oxides and salts of, 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 20 parts of lauryl gallate was mixed with di-ethyl adipate so
A methoxymethylolated melamine initial condensate (trade name Nikalunk MS-11, manufactured by Nippon Carbide Kogyo Co., Ltd., formaldehyde substitution degree 100%) was added to a solution obtained by dissolving yr+ in a mixed solution of 50 parts of di-n-butyl adipate. , methylation degree 100%, average number of nuclei 1.6), 36 parts solid content,
Addition and mixing gave an internal phase solution.

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 4.5 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 4.0 μm, the temperature of this system was raised to 60°C.

Next, 0.5N hydrochloric acid was gradually added to this system with stirring to adjust the pH of the system to 3.5, and then the temperature of the system was gradually raised to 80°C, and further at 80°C. The reaction was carried out for 5 hours to obtain a milky white capsule dispersion.

20 parts of wheat starch powder and 10 parts of pulp powder were added and mixed to the obtained capsule dispersion, and water was added to make the solid content concentration 25% to prepare a capsule coating liquid of 40 g/rrr.
It was coated on paper using an air knife coater so that the solid content was 5 g/rrf.

Preparation of single pressure sensitive copying paper To an aqueous solution prepared by adding 89 parts of t-butylbenzoic acid, 125 parts of diphenyl phosphate, and 70 parts of sodium laurylbenzenesulfonate to 800 parts of a 5% aqueous solution of caustic soda,
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 500 parts of a 20% aqueous solution of sodium t-butylbenzoate was added to this dispersion. Then, 425 parts of TiCl was gradually added to this dispersion under strong stirring to obtain a pale yellow fine particle dispersion, which was then filtered and washed to obtain a slurry.

Next, 1 part of sodium polyacrylate and 1 part of hydroxyethylcellulose were dissolved in 200 parts of water, and 20 parts of the above slurry in terms of solid content, 20 parts of titanium oxide, and 60 parts of calcium carbonate were added thereto, and the mixture was strongly dispersed. 15 parts of a carboxy-modified styrene-butadiene copolymer Radesox (solid content concentration 50%) was added to the dispersion to obtain a coating liquid.

The resulting coating liquid was applied onto the coated surface of the capsule-coated paper using an air knife coater to give a dry weight of 5 g/rrf to obtain a single pressure-sensitive copying paper.

Evaluation When the single pressure-sensitive copying paper prepared as described above was printed using a ribbonless typewriter, a clear colored image was obtained.

Separately, this copy paper was treated at 100° C. for 3 hours, but no stains were observed on the sheet, indicating that it had good core material retention.

Example 2.3 As a methoxymethylolated melamine initial condensate, Cymel 300° or Cymel 301 (manufactured by Mitsui Toatsu Chemical Co., Ltd., both have a formaldehyde substitution degree of 100%, a methylation degree of 100%, and an average nuclear Capsules were prepared in exactly the same manner as in Example 1, except that 36 parts of (1.1) solids were used, and a single pressure-sensitive copying paper was produced. Subsequently, the same evaluation as in Example 1 was conducted, and it was found that it had good core material retention properties.

Example 4 320 g of 37% formaldehyde aqueous solution, IN NaOH
8cc of aqueous solution and 20g of melamine at 30~35℃ for about 2 hours.
The mixture was stirred for 0 minutes to dissolve the melamine, and left at room temperature for 1 day to precipitate hexamethylolmelamine crystals. After suction filtration of the crystals, the filtrate was washed with methanol several times using a BTB indicator until it turned yellow-green, then methanol was added to this to make a total amount of 400 g, and a 0.5N-HC1 aqueous solution was heated to its boiling point while stirring. 1cc was added, and the crystals were dissolved by reacting for about 15 minutes, and then 0.5 N -NaOH aqueous solution was added until the BTB indicator showed green color.

Next, this was cooled, filtered to remove trace impurities, concentrated under reduced pressure at a temperature below 50°C to about 68 g, and then left at room temperature to crystallize the entire product. Recrystallization was performed several times with methanol to obtain a hexamethoxymethylolmelamine initial condensate (degree of formaldehyde substitution 100%, degree of methylation 100%, average number of nuclei 1).

Subsequently, capsules were prepared in exactly the same manner as in Example 1, except that 36 parts of the above-mentioned hexamethoxymethylolmelamine initial condensate was used as a solid content instead of Nikarasoku MS-11, and a single pressure-sensitive copying paper was prepared. Then, the same evaluation as in Example 1 was carried out, and it was found that it had good core material retention.

Comparative Example 1 A procedure was carried out in exactly the same manner as in Example 1, except that 36 parts of Niepan 120 (manufactured by Mitsui Toatsu Chemical Co., Ltd.), which is an n-butoxymethylolated melamine initial condensate, was used as a solid content instead of Nikarasoku MS-11. Capsules were prepared and a single pressure-sensitive copying paper was made. Next, the same evaluation as in Example 1 was performed, and it was found that the sheet became stained after being treated for 3 hours at 100°C, indicating that the core material retention was poor.

Comparative Example 2 Capsules were produced in the same manner as in Example 1, except that 36 parts of Kneepan 165 (manufactured by Mitsui Toatsu Chemical Co., Ltd.), which is a 1so-butoxymethylolated melamine initial condensate, was used as a solid content instead of Nikarasoku MS-11. When the paper was prepared and evaluated, it was found that the core material retention property was poor.

Patent applicant Kanzaki Paper Co., Ltd. Commissioner of the Patent Office 1. 'Indication of the case 1982 Patent Application No. 107423 2 Name of the invention Method for manufacturing microcapsules 3 Person making the amendment 4 Address of agent (660) Inside Kanzaki Paper Co., Ltd., 1-11 Jokoji Motomachi, Amagasaki City 6.? ili Correct subject matter Column 7 of "Claims" and "Detailed Description of the Invention" of the specification, Contents of amendment As shown in the attached sheet (Contents of amendment) (1) The scope of claims is corrected as follows.

(Note) (11) After emulsifying the hydrophobic core material containing the melamine-formaldehyde initial condensate in water or a hydrophilic medium,
A method for producing microcapsules, characterized by using a chilled methylolmelamine initial condensate, which is a microencapsulation method that promotes polycondensation to form a wall film.

(2) Polycondensation is carried out at a temperature of 70°C or higher or at a pH of 5.0
The manufacturing method according to claim (1), wherein the manufacturing method is carried out by maintaining the temperature at 60° C. or higher for 2 hours or more.

(3) The production method according to claim fl) or (2), wherein the water or the hydrophilic medium contains an anionic polymer having no hydroxyl group or amide group.

(4) The production method according to claim (3), wherein the anionic polymer is a maleic anhydride-based copolymer, an acrylic acid-based, a methacrylic acid-based, or a crotonic acid-based polymer or copolymer. .

(2) "...Hydrophobic..." on page 7, line 1.7, page 8, line 1, and line 14 of the same page is 1...oil-soluble...
・Corrected to ``.

(3) Lines 14 to 16 of page 12 of the bibliography are amended to the following explanation.

(Note) In the present invention, other aldehyde resin precondensates used in combination with the methylated methylolmelamine precondensate are preferably used completely dissolved in the hydrophobic core material, but they may be partially dissolved. It can be used even in a closed state.

(4) Replace “...amino compound or phenol compound...” on page 13, line 2 of the specification with “melamine.
...” is corrected.

(5) On page 15, line 7 of the specification, replace “...ethylene” with “
...Ethylene-'' is corrected.

(6) After “polymer” on page 15, line 11 of the specification, “,
``Styrene-maleic anhydride copolymer'' is replenished.

(7) Add "funnel oil" after "...sodium benzene-m-disulfonate" on page 18, line 9 of the specification.

(8) On page 19, lines 2 to 3 of the specification, "this tends to occur during preparation under severe conditions such as the present invention" is corrected to "during capsule preparation."

(that's all)

Claims (4)

[Claims] (1) In a microencapsulation method in which a hydrophobic core material containing a melamine nivolmaldehyde initial condensate is emulsified in water or a hydrophilic medium and then polycondensation is promoted to form a wall film, the initial condensate is A method for producing microcapsules, characterized in that a hydrophobic methylated methylolmelamine initial condensate is used as the precondensate. (2) Polycondensation is carried out at a temperature of 70°C or higher or at a pH of 5°0
The manufacturing method according to claim 11, wherein the manufacturing method is carried out by maintaining the temperature at 60° C. or higher for 2 hours or more. (3) The production method according to claim (1) or (2), wherein the water or the hydrophilic medium contains an anionic polymer having no hydroxyl group or amide group. (4) The production method according to claim (3), wherein the anionic polymer is a maleic anhydride-based copolymer, an acrylic acid-based, a methacrylic acid-based, or a crotonic acid-based polymer or copolymer.