JPS60238141A - Preparation of powdery microcapsule - Google Patents

Abstract

PURPOSE:To remove a dispersing medium from a high concn. dispersion as it is, by adding an aldehyde resin forming material to a microcasule dispersion, to which a water-soluble polymer is added to an emulsifier, to perform reaction and subsequently removing the dispersing medium thereof. CONSTITUTION:One or more of a water soluble polymer selected from a maleic anhydride type copolymer and an acrylic acid type, a methacrylic acid type or a crotonic acid type polymer or copolymer is added as an emulsifier to prepare a microcapsule dispersion. An aldehyde resin forming material is added to said microcapsule dispersion and, after reaction, the dispersing medium of said dispersion is removed to obtain a powdery microcapsule. As the aforementioned aldehyde resin forming material, a methylol melamine precondensate, an alkylated methylol melamine precondensate or a methylol urea precondensate can be designated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing powder capsules, and more particularly to a method for producing powder capsules very easily.

Microcapsules are suitable for stably holding unstable substances (reactive substances, liquid substances, etc.), and are applied to medicines, agricultural chemicals, foods and drinks, fragrances, dyes, adhesives, fuels, etc. . The most well-known use is pressure-sensitive copying paper, which has been used for over 30 years.

Conventionally known methods for producing microcapsules include methods with coacervation (for example, U.S. Pat. No. 2,800,457).
No. 2800458), interfacial polymerization method (e.g., Japanese Patent Publication No. 3B-19574, Japanese Patent Publication No. 42
-446, Special Publication No. 42-771, Special Publication No. 49-45
133 etc.), 1n-situ polymerization method (
For example, Japanese Patent Publication No. 36-9168, Japanese Patent Publication No. 51-907
No. 9, Japanese Unexamined Patent Publication No. 53-84881, etc.) are known, and a large number of techniques have been developed.

However, with such known techniques, it is very difficult to manufacture powdered capsules by encapsulating a hydrophobic core material in water or a hydrophilic medium and removing the dispersion medium of the capsule dispersion. This is because, in such a process, there is a strong tendency for capsules to aggregate, and there is a water-soluble polymer in the capsule dispersion medium that causes the capsules to adhere to each other, so if you simply try to remove the dispersion medium from the dispersion liquid, This is because the capsule becomes a huge agglomerate.

Therefore, methods have been proposed in which the capsule dispersion is diluted to an extremely low concentration and then dried under high shear conditions by spray drying, etc., but this method not only requires an extremely large amount of energy but also requires an extremely complicated process. It becomes something.

In view of the current situation, the present inventors conducted extensive research on a method for producing powder capsules, and found that when a specific post-treatment is applied to a microcapsule dispersion liquid, the dispersion medium can be highly concentrated through a simple drying process. It was discovered that the dispersion can be removed very easily even in the form of a dispersion, and the present invention was achieved.

The present invention provides a method for producing powder capsules, which comprises adding an aldehyde resin-forming material to a dispersion of opened microcapsules using a water-soluble polymer as an emulsifier, allowing the reaction to occur, and then removing the dispersion medium. It is.

In the present invention, the aldehyde resin forming material added to the capsule dispersion medium includes, for example, a phenol-formaldehyde resin initial condensate, an aminoaldehyde resin initial condensate, and at least one selected from phenols or amines and an aldehyde. Examples include combinations of at least one type of compound selected from the following. These are preferably water-soluble, but even if they are sparingly soluble in water, they can be used in a dispersed form.

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.

Examples of the aminoaldehyde resin initial condensate include at least one amine such as urea, thiourea, alkyl urea, ethylene urea, acetoguanamine, benzoguanamine, melamine, guanidine, dicyandiamide, biuret, and cyanamide, and formaldehyde, acetaldehyde, and paraformaldehyde. Initial condensates obtained by condensing at least one kind of aldehyde such as dihydrogen, hexamethylenetetramine, geltaraldehyde, glyoxal, and furfural, or alkylated products such as methylated products thereof, and anion, cation, or nonionic modification thereof Examples include things.

Examples of anionic modifiers include sulfamic acid, sulfanilic acid, glycolic acid, glycine, acidic sulfite, phenol sulfonate, and taurine, and examples of cationic modifiers include diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and dimethylamino. Examples of nonionic modifiers include ethanol and the like, and examples of nonionic modifiers include ethylene glycol and diethylene glycol.

When added as a combination of at least one compound selected from phenols or amines and at least one compound selected from aldehydes, the phenols, amines, and aldehydes include those exemplified in the above initial condensate. Examples include compounds.

In addition, when aldehydes are already present in the dispersion medium, such as in formaldehyde resin-based microcapsule dispersions, the present invention can be achieved by simply adding phenols or amines as aldehyde-based resin forming materials. You can achieve your purpose. However, since the removal properties of the dispersion medium are poor, it is desirable to add both in combination as described above.

Examples of the aldehyde resin-forming material used in the present invention include the materials listed above, among them methylolmelamine initial condensate, alkylated methylolmelamine initial condensate, methylolurea initial condensate, and alkylated methylolurea initial condensate. , methylol urea melamine initial condensate, alkylated methylol urea melamine initial condensate, and a combination of urea and formaldehyde are preferred, especially alkylated methylol, which has both oil-soluble and water-soluble properties, because it is easy to powderize capsules. Most preferably used are a melamine initial condensate, an alkylated methylol urea initial condensate, and an alkylated methylol urea melamine initial condensate.

The amount of the above-mentioned aldehyde-based resin-forming material added cannot be determined exactly because it varies depending on the capsule cleavage method used, the type of capsule membrane material and emulsifier, the amount used, etc., but it is generally based on the weight of 100 capsules. part (solid content), 0.1 to 100 parts by weight, more preferably 0.
．． 5 to 30 parts by weight are added.

The microcapsules of the present invention can be prepared using any conventionally known coacervation method, interfacial polymerization method, 1n-situ method, etc., as long as they are prepared in water or a hydrophilic medium using a water-soluble polymer as an emulsifier. It may be obtained by any technique, but in particular, a hydrophobic core material containing an oil-soluble amino-aldehyde resin initial condensate may be emulsified in water or a hydrophilic medium under conditions that promote polycondensation. Microcapsules obtained by forming a wall film with a powder are preferable because powder capsules having good core substance retention properties can be obtained.

In particular, when an oil-soluble melamine-formaldehyde resin initial condensate is used as the oil-soluble amino-aldehyde resin initial condensate, powder capsules with good solvent resistance can be obtained. The initial condensate has a formaldehyde substitution degree of 40 to 100%,
In the case of an initial condensate having an alkylation degree of 80 to 100% and a hydrophobicity of 6 to 8, particularly in the case of an initial condensate containing hexamethoxyhexamethyolmelamine as a main component, the capsule performance and powder Capsules in an extremely good state of oxidation can be obtained.

Note that the degree of formaldehyde substitution is a value indicating what percentage of the active hydrogens possessed by the amino groups of melamine are substituted with methylol groups, alkoxymethylol groups, and methylene groups, and is expressed by the following formula.

Furthermore, the degree of alkylation is a value indicating what percentage of the methylol group is alkoxylated, and is expressed by the following formula.

The degree of hydrophobicity is the total number of carbon atoms in all alkyl groups per melamine residue.

In the present invention, water-soluble polymers used as emulsifiers when preparing microcapsules include anionic, nonionic, cationic, and amphoteric polymers.

The anionic polymer may be natural or synthetic, such as -coo-, -so;, -opo
;- groups, etc., specifically gum arabic, carrageenan, sodium alginate, pectic acid,
Natural polymers such as gum tragacanth, almond gum, agar, carboxymethyl cellulose, sulfated cellulose,
Semi-synthetic polymers such as 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, vinylbenzenesulfonic acid-based or 2
- Acrylamide-2-methyl-propanesulfonic acid polymers and copolymers, partial amides or partial esters of such polymers and copolymers, carboxy-modified polyvinyl alcohol, sulfonic acid-modified polyvinyl alcohol, phosphoric acid-modified polyvinyl Examples include synthetic polymers such as alcohol.

More specifically, examples of maleic anhydride copolymers (including hydrolyzed ones) include methyl vinyl ether-maleic anhydride copolymers, ethylene-maleic anhydride copolymers, and vinyl acetate-maleic anhydride copolymers. Polymer, methacrylamide-maleic anhydride copolymer, isobutylene-maleic anhydride copolymer, styrene-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''), ethyl acrylate-acrylic acid , methyl acrylate-methacrylic acid, methyl meccrylate-acrylic acid, methyl methacrylate-meccrylic acid, methyl acrylate-acrylamide-acrylic acid, acrylonitrile-acrylic acid,
Acrylonitrile-methacrylic acid, hydroxyethyl acrylate-acrylic acid, hydroxyethyl methacrylate-methacrylic acid, vinyl acetate-acrylic acid, vinyl acetate-methacrylic acid, acrylamide-acrylic acid, acrylamide-methacrylic acid, methacrylamide-acrylic acid, methacrylamide- Examples include copolymers such as methacrylic acid and vinyl acetate-crotonic acid.

Examples of the vinylbenzenesulfonic acid copolymer or 2-acrylamido-2-methyl-propanesulfonic acid copolymer include methyl acrylate-vinylbenzenesulfone # (or salt thereof) copolymer, and vinyl acetate-vinylbenzenesulfonic acid copolymer. Polymer, acrylamide-vinylbenzenesulfonic acid copolymer, acryloylmorpholine-vinylbenzenesulfonic acid copolymer, vinylpyrrolidone-vinylhenzenesulfonic acid copolymer, vinylpyrrolidone-2-acrylamide-2-methyl-propanesulfone Examples include acid copolymers.

The nonionic polymer may also be natural or synthetic, and includes, for example, those having -0H groups.

Specific nonionic semi-synthetic polymers include hydroxyethylcellulose, methylcellulose, pullulan (an amorphous, easily water-soluble polymeric polysaccharide made from starch by microbial fermentation), soluble starch, oxidized starch, etc. can be mentioned.

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.

Among these, preferred emulsifiers are maleic anhydride-based copolymers, acrylic acid-based, methacrylic acid-based, or crotonic acid-based polymers and copolymers.

In addition, in the method of the present invention, when a low-molecular-weight emulsifier is further used in combination with the water-soluble polymer as described above, capsules that are extremely easy to powder can be obtained.

The low molecular weight emulsifiers include anionic, cationic,
Examples include nonionic and amphoteric emulsifiers, but anionic emulsifiers are preferred, and salts of organic sulfuric acid or organic phosphoric acid are particularly preferably used.

Specifically, otrium vinylsulfonate, sodium benzenesulfonate, sodium henzenesulfinate,
p-) Sodium toluenesulfonate, p-) Sodium toluenesulfinate, sodium p-vinylbenzenesulfonate, sodium p-i-amylbenzenesulfonate, sodium naphthalene-α-sulfonate, sodium naphthalene-β-sulfonate, 2-methylnaphthalene-6
-Sodium sulfonate, 2,6-dimethylnaphthalene-8-sodium sulfonate, 2,6-dimethylnaphthalene-3-sodium sulfonate, 1-naphthol-4
-sodium sulfonate, sodium benzene-m-disulfonate, funnel oil, sodium diphenyl phosphate,
Examples include sodium phenylphosphonate, sodium di-n-butyl phosphate, sodium diamyl phosphate, and the like.

Emulsifiers such as those mentioned above can be added at 0.01% in water or a hydrophilic medium.
The content is preferably 0.1% or more from the viewpoint of ease of cleavage of the emulsion and stabilization of the emulsion. In particular, in the range of 0.3 to 3%, capsule cleavage becomes extremely easy and capsules that can be easily powdered can be obtained. The upper limit of the amount used is determined by the viscosity of the system or the capsule cleavage device, etc., but generally it is 2.
It is desirable to keep it below 0%.

In the present invention, an aldehyde resin-forming material is added and reacted with a microcapsule dispersion prepared in water or a hydrophilic medium using a water-soluble polymer as described above as an emulsifier. The addition may be made during the formation of the capsule wall, at a point when only a thin capsule wall is formed.

The reaction of the added aldehyde-based resin forming material is promoted by operations such as raising the temperature and adjusting the PHa. The reaction conditions are generally P 5.5 or less, 60°C or more, more preferably P
The treatment is performed at H4.0 or lower and at 80° C. or higher for several minutes to several hours, but the conditions are not particularly limited.

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, 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,
Liquid crystals, temperature indicating materials, flame retardants, etc.

In the present invention, the dispersion medium of the capsule dispersion may be used as a post-treated dispersion, or after passing through a concentration process such as filtration,
Ventilation drying, surface drying, fluidized drying, flash drying, spray drying,
Most of the powder is removed by means such as vacuum drying, freeze drying, infrared drying, high frequency drying, ultrasonic drying, and pulverization drying to form powder capsules.

In addition, the powder capsules obtained by the present invention have a stronger hydrophobic tendency than those obtained by conventionally known encapsulation methods, and therefore have the characteristic that they can be extremely easily dispersed in a hydrophobic medium. and known ink media, such as electron beam (or ultraviolet) curable ink, hot melt ink,
Capsule ink can be easily prepared by dispersing it in flexographic ink, letterpress ink, etc.

Furthermore, if necessary, the powder capsule of the present invention can be used again after being dispersed in water or a hydrophilic medium, but in that case, the above-mentioned emulsifier described for capsule preparation and other known emulsifiers may be used. It is preferable to use a surfactant or the like.

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 25 parts of lauryl gallate and 2 parts of N,N-dimethylhensylamine were mixed with 50 parts of phenyl cellosolve and di-adipate.
A methoxymethylolated melamine initial condensate (trade name Cynor 350, manufactured by Mitsui Toatsu Chemical Co., Ltd.) containing hexamethoxyhexamethylolmelamine as a main component was solidified in a solution obtained by dissolving it in a mixed solution with 50 parts of n-butyl. A total of 62 parts of the mold was added and mixed to obtain an internal phase liquid.

Separately, in a stirring mixing vessel equipped with a heating device, 2 parts of ethylene-maleic anhydride copolymer (trade name EMA-31, manufactured by Monsanto) and ethylene-maleic anhydride polymer copolymer (trade name EMA-81) were placed. An aqueous solution prepared by heating and melting 0.3 parts (manufactured by Monsando) in 300 parts of water was added, a 5% aqueous solution of caustic soda was added to adjust the pH to 4.0, and 0.3 parts of funnel oil was added. 6 parts were added to form an aqueous medium for making capsules.

This aqueous medium was heated to 85°C, and the internal phase liquid was emulsified and dispersed therein so that the average particle size was 7.0 μm.
The reaction was carried out at 5°C for 3 hours. Subsequently, this system was stirred to 0
．． 05N- Hydrochloric acid was gradually added over 5 hours to reduce the P of the system.
H was adjusted to 3.5, the temperature of the system was further raised to 95°C, and the reaction was carried out at 95°C for 5 hours.

Subsequently, 20 parts of Cynull 3500 10% aqueous solution was added to 95%
The mixture was added dropwise to the capsule dispersion at 95° C. with strong stirring, and reacted for 1 hour at 95° C. to obtain a thickened capsule dispersion.

The resulting capsule dispersion was filtered by suction, and the paste was dried to obtain a powder capsule containing a ligand compound, which was mainly a mononuclear capsule.

Comparative Example Capsules were prepared in the same manner as in Example 1 up to the stage before dropping 20 parts of a 10% aqueous solution of Cymel 350. after that,
No. IMEL 350 aqueous solution was not added dropwise, the paste was filtered by suction as it was, and the paste was dried, but the capsules were difficult to powder and good mononuclear capsules could not be obtained.

Example 2 A flame retardant-containing powder capsule was obtained in the same manner as in Example 1, except that 31 parts of Cymel 350 was added in solid form to 100 parts of trichloroethyl phosphate to prepare an internal phase liquid.

Example 3 Same as Example 1 except that 31 parts of Cymel 350 was added in solid form to a mixed solution of 10 parts of geraniol acetate and 90 parts of alkylnaphthalene (trade name: KMC Oil, manufactured by Kureha Chemical Co., Ltd.) to prepare an internal phase liquid. A fragrance-containing powder capsule was obtained.

Example 4 A camphor-containing powder capsule was obtained in the same manner as in Example 1 except that 10 parts of camphor was dissolved in 90 parts of alkylnaphthalene, and 31 parts of Cymel 350 was added as a solid content and mixed to form an internal phase liquid. Ta.

Example 5 72 parts of Crystal Violin Tract and 5 parts of phenol resin were dissolved in 50 parts of stearyl alcohol, and 5 parts of n-propyl alcohol and 31 parts of Cymel 350 were added and mixed as solids to form an internal phase liquid. A powder capsule containing a temperature-indicating material was obtained in the same manner as in Example 1.

Example 6 20 parts of toluene, 35 parts of n-butanol, and 31 parts of Cymel 350 were added as solids to a mixture of 15 parts of cholesterol benzoate, 15 parts of cholesterol n-nonanoate, and 15 parts of cholesterol stearate. A liquid crystal-containing powder capsule was obtained in the same manner as in Example 1, except that the internal phase liquid was prepared using a liquid crystal.

Example 7 Aromatic polyvalent isocyanate (trade name: Coronate) was added to a solution obtained by dissolving 24 parts of Crystal Violin Tract in 100 parts of alkylnaphthalene.

(manufactured by Nippon Polyurethane Co., Ltd.) was melted to obtain an internal phase liquid.

Separately, add EMA-31 in a stirred mixing vessel equipped with a heating device.
, 3 parts by heating and melting in 200 parts of water, an aqueous solution prepared by heating and melting was added, and a 5% aqueous solution of caustic soda was added to the P H
was adjusted to 3.5, and 2 parts of funnel oil was further added to prepare an aqueous medium for capsule production.

The internal phase liquid was emulsified and dispersed in this aqueous medium so that the average particle size was 7.0 μm, and then the temperature was raised to 95° C. and the mixture was reacted for 3 hours.

Subsequently, 50 parts of a 10% aqueous solution of Cymel 350 was heated at 95°C.
The mixture was added dropwise to the capsule dispersion below with strong stirring, and then reacted at 95° C. for 1 hour to obtain a thickened capsule dispersion.

The resulting capsule dispersion was suction-filtered, and the paste was further dried to obtain color-forming agent-containing powder capsules mainly consisting of mononuclear capsules.

Patent applicant Kanzaki Paper Co., Ltd.

Claims (1)

[Scope of Claims] (1) A powder characterized by adding an aldehyde resin-forming material to a microcapsule dispersion liquid cleaved using a water-soluble polymer as an emulsifier, reacting it, and then removing the dispersion medium. Method of manufacturing capsules. (2) The aldehyde resin forming material is a methylol melamine initial condensate, an alkylated methylol melamine initial condensate, a methylol urea initial condensate, an alkylated methylol urea initial condensate, a methylol urea melamine initial condensate, or an alkylated methylol urea melamine initial condensate. The manufacturing method according to claim (1), which is at least one selected from a condensate and a combination of urea and formaldehyde. +3) The microcapsule dispersion is obtained by emulsifying a hydrophobic core material containing an oil-soluble aminoaldehyde resin initial condensate in water or a hydrophilic medium and forming a wall film under conditions that promote polycondensation. The manufacturing method according to claim (1), which is a microcapsule dispersion liquid. (4) The production method according to claim (3), wherein the oil-soluble amino-aldehyde resin initial condensate is an oil-soluble melamine-formaldehyde resin initial condensate. (5) The oil-soluble melamine-formaldehyde resin initial condensate has a degree of formaldehyde substitution of 40 to 100%, a degree of alkylation of 80 to 100%, and a degree of hydrophobicity of 5 to 8. 4) The manufacturing method described in section 4). (6) The production method according to claim (5), wherein the oil-soluble melamine-formaldehyde resin initial condensate is an initial condensate containing hexamethoxyhexamethylolmelamine as a main component. (Claim 11), wherein the water-soluble polymer is at least one selected from maleic anhydride-based copolymers, acrylic acid-based, metharylic acid-based, or crotonic acid-based polymers and copolymers. Production method. (8) The manufacturing method according to claim 11, characterized in that a low-molecular emulsifier is used in combination with the water-soluble polymer as an emulsifier.