JPS60166027A - Preparation of powdery capsule - Google Patents

Abstract

PURPOSE:To prepare powdery capsule with ease by emulsifying a hydrophobic core material contg. initial stage condensation product of melamine-formaldehyde resin with water, etc. to form the wall film of microcapsule and prepg. liquid dispersion of the microcapsule, then removing the dispersion medium. CONSTITUTION:A hydrophobic core material contg. an initial stage condensation product of melamine-formaldehyde resin consisting essentially of hexamethoxy hexamethylolmelamine, having 40-100% degree of substitution with formaldehyde, 80-100% degree of alkylation, and 4-20 degree of hydrophobicity, etc. is emulsified in water or hydrophilic medium. Then, under conditions for promoting polycondensation (such as, maintaining the reaction system at >=80 deg.C for >=2hr, and adjusting the pH more than once with acid in the midway of the reaction), the wall film of the micrcapsule is formed to prepre the dispersion of the microcapsule, and the dispersion medium is removed. By this method, powdery capsule is obtd. easily.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing powder capsules, and more particularly to a method for manufacturing 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 the coacervation method (for example, U.S. Pat. No. 2,800,457).
19574-19574,
-446, Special Publication No. 42-771, Special Publication No. 49-45
138 etc.), 1n-situ polymerization method polymerization ratio, Japanese Patent Publication No. 36-9168, JP-A-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 a specific oil-soluble amino-aldehyde resin initial condensate was used as a capsule wall material in a hydrophobic core material. The present inventors have discovered that the dispersion medium of the obtained microcapsule dispersion can be removed extremely easily by a simple drying process while remaining a highly concentrated dispersion, and the present invention has been achieved based on this discovery.

The present invention provides a hydrophobic core material containing a melamine-formaldehyde resin initial condensate having a degree of formaldehyde substitution of 40 to 100%, a degree of alkylation of 80 to 100%, and a degree of hydrophobicity of 4 to 20, in water or a hydrophilic medium. This is a method for producing powder capsules, which comprises preparing a microcapsule dispersion by forming a wall film under conditions that promote emulsification and polycondensation, and then removing the dispersion medium.

The melamine resin initial condensate used in the present invention must be completely or partially dissolved in the hydrophobic core material, and its formaldehyde substitution degree and alkylation degree may be adjusted as appropriate within the above range depending on the HLB of the core material. , the degree of hydrophobicity is adjusted.

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

00 Further, 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, and the initial stage of melamine resin in which the degree of hydrophobicity is 5 to 12, more preferably 5 to 8. Condensates are preferably used because particularly good powder capsules can be obtained, and among them, melamine resin initial condensates containing hexamethoxyhexamethylolmelamine or triethoxytrimethylolmelamine as a main component are most preferably used.

In addition, in the present invention, the average number of nuclei represented by the average number of melamine residues contained in one molecule of the initial condensate is 1 to 1.
An initial condensate having a molecular weight of 0, more preferably 1 to 5 is more preferably used.

Furthermore, in the present invention, one or more other aldehyde'-based resin initial condensates can be used in combination with the melamine resin initial condensate for the purpose of changing the performance of the membrane material. 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.

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 condensate obtained by condensing at least one aldehyde such as hexamethylenetetramine, geltaraldehyde, glyoxal, furfural, etc., or an alkylated product or a partially alkylated product thereof, and anion, cation, or nonionic modification thereof. Among these, hydrophobic ones can be mentioned.

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.Cationic modifiers include diethylenetriamine, triethylenetetramine, and tetraethylenepentamine. , dimethylaminoethanol and the like. Furthermore, examples of nonionic modifiers include ethylene glycol, diethylene glycol, etc., and these are used to the extent that the initial condensate does not lose its hydrophobicity.

In the present invention, when the melamine resin initial condensate is dissolved in the hydrophobic core material, if the initial condensate used is insufficient in solubility or has high viscosity, the hydrophobic core material in which the initial condensate is dissolved may be When the viscosity is high, a low boiling point solvent or a polar solvent may be used in combination. Examples of low boiling point solvents used for this include n-pentane, methylene chloride, ethylene chloride, carbon disulfide, acetone, methyl acetate, chloroform, and methyl. alcohol, tetrahydrofuran,
n-hexane, carbon tetrachloride, ethyl acetate, ethyl alcohol, n-propyl alcohol, 1so-7' lobil alcohol, n-butyl alcohol, 1so-butyl alcohol, t-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.

In the present invention, it is preferable that the melamine resin initial condensate is used dissolved in the hydrophobic core material, but it is also possible to use it in a dispersed state.

In addition, the amount of the melamine resin initial condensate to be blended depends on the type of the initial condensate used, the type and amount of 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 it cannot be determined generally, it is preferably 2 parts by weight or more and 50 parts by weight or less in terms of melamine, particularly 4
It is more preferably 30 parts by weight or more.

When the hydrophobic core material used is a solid, the solid is dispersed in the initial condensate or a low boiling point solvent in which the initial condensate is dissolved, and then emulsified in water or a hydrophilic medium. .

The conditions for promoting polycondensation in the present invention vary depending on the type of melamine resin initial condensate used and the purpose of use of the capsule, and cannot be determined to one type, but conditions include a temperature of 70°C or higher, or a condition of PH5.0 or lower and 60°C or higher. It is preferable to maintain the temperature at 80° C. or higher for 2 hours or more, and in particular, if the temperature is maintained at 80° C. or higher for 2 hours or more and the pH is sub-adjusted with an acid at least once during the reaction, capsules that are easier to powder can be obtained.

In the method of the present invention, if the hydrophobic core material containing the melamine resin 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. Anionic, nonionic, cationic, amphoteric polymers, low molecular weight emulsifiers, etc. are preferably used.

The anionic polymer may be natural or synthetic, such as -coo-, so, l0POS-
Specific examples include gum arabic, carrageenan, sodium alginate, pectic acid, gum tragacanth, almond gum, natural polymers such as agar ring,
Carboxymethylcellulose, sulfated cellulose, sulfated methylcellulose, carboxymethyl starch, phosphorylated starch, semi-synthetic polymers such as lignin sulfonic acid, maleic anhydride-based (including hydrolyzed) copolymers, acrylic acid-based, methacrylate Acid-based or crotonic acid-based polymers and copolymers, vinylbenzenesulfonic acid-based or 2-acrylamido-2-methyl-propanesulfonic acid-based polymers and copolymers, and such polymers and copolymers. Synthetic polymers such as partially amide or partially esterified products, carboxy-modified polyvinyl alcohol, sulfonic acid-modified polyvinyl alcohol, and phosphoric acid-modified polyvinyl alcohol are included.

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

'Acrylic acid copolymers, methacrylic acid copolymers, and crotonic acid copolymers include methyl acrylate.
Acrylic acid copolymer (hereinafter abbreviated as 'copolymer') Ethyl acrylate-acrylic acid, Methyl acrylate-methacrylic acid, Methyl methacrylate-acrylic acid, Methyl methacrylate-methacrylic 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,
Examples include copolymers of acrylamide-methacrylic acid, meccrylamide-acrylic acid, methacrylamide-methacrylic acid, and vinyl acetate-crotonic acid.

Examples of vinylbenzenesulfonic acid copolymers or 2-acrylamido-2-methyl-propanesulfonic acid copolymers include methyl acrylate-vinylbenzenesulfonic acid (or salts thereof) copolymers, and vinyl acetate-vinylbenzenesulfonic acid copolymers. Polymer, acrylamide-vinylbenzenesulfonic acid copolymer, acryloylmorpholine-vinylhenzenesulfonic acid-1'' polymer, vinylpyrrolidone-
Vinylbenzenesulfonic acid copolymer, vinylpyro IJ
Examples include l'non-acrylamide-2-methyl-propanesulfonic acid copolymer.

The nonionic polymer may also be natural or synthetic, and includes, for example, one having -0I] group.

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.

Examples of low-molecular emulsifiers include anionic, cationic, nonionic, and amphoteric emulsifiers, but anionic ones are preferred, and among them, organic sulfuric acids having a total carbon number of 1 to 14 or Preferred are Li", Na+, K", and NlI4+ salts of organic phosphoric acids, specifically sodium vinylsulfonate, sodium benzenesulfonate, sodium benzenesulfinate, sodium p-toluenesulfonate, and sodium p-toluenesulfinate. , sodium p-vinylhenzenesulfonate, sodium p-1-amylbenzenesulfonate, sodium naphthalene-α-sulfonate, sodium naphthalene-β-sulfonate, sodium 2-methylnaphthalene-6-sulfonate, 2.6 -Dimethylnaphthalene-8-sodium sulfonate, 26-dimethylnaphthalene-3-sodium sulfonate, 1-naphthol-
Examples include sodium 4-sulfonate, sodium benzene-m-disulfonate, funnel oil, sodium diphenyl phosphate, sodium phenylphosphonate, sodium di-n-butyl phosphate, sodium di-amyl phosphate, and the like.

In the method of the present invention, it is preferable to use one or more of the various emulsifiers mentioned above, but in particular, when a polymer emulsifier and a low-molecular emulsifier are used in combination, capsules that are extremely easy to powder can be obtained. , is a particularly preferred embodiment.

Emulsifiers such as those mentioned above can be used at 1% O4 in water or a hydrophilic medium.
It is desirable that the content be at least 0.1%, and from the viewpoint of ease of preparing an emulsion and stabilization of the emulsion, it is preferable that the content be 0.1% or more. In particular, in the range of 0.3 to 3%, capsule preparation 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 preparation equipment, but generally 2
It is desirable to keep it below 0%.

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, valatoluenesulfonic acid, hydrochloric acid, and sulfuric acid, are used to maintain the reaction system acidic. It will be done.

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 thylate, 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 prepared by dissolving an electron-donating color former, an electron-accepting color developer, a ligand compound, an organic metal salt, etc. in an insoluble or substantially water-insoluble liquid or the above synthetic oil;
Water-insoluble metal oxides and salts, fibrous materials such as cellulose or asbestos, water-insoluble synthetic polymeric materials, minerals, pigments, glasses, fragrances, flavoring agents, fungicidal compositions, Physiological compositions, fertilizer compositions.

In the present invention, the dispersion medium of the capsule dispersion may be used as the prepared dispersion, or after passing through a concentration process such as filtration, through air drying, surface drying, fluidized drying, flash drying, spray drying, vacuum drying, and freeze drying. Most of the powder is removed by means such as infrared drying, high frequency drying, ultrasonic drying, pulverization drying, etc. 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 Hexamethoxyhexamethylolmelamine was added to a solution obtained by dissolving 20 parts of lauryl gallate and 10 parts of trihensylamine in a mixed solution of 50 parts of di-ethyl adipate and 50 parts of di-n-butyl adipate. Methoxymethylolated melamine initial condensate (trade name: Nikaratsuku MS)
-11, manufactured by Nippon Carbide Industries Co., Ltd.) in solid content of 42 parts,
The mixture was added and mixed 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 4.5 to obtain an aqueous medium for capsule production.

After emulsifying and dispersing the internal phase liquid in this aqueous medium so that the average particle size was 4.0μ, the system was heated to 80”c,
The reaction was allowed to proceed for 1 hour.

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 90°C, and further to 90'C. The mixture was reacted for 5 hours to obtain a milky white capsule dispersion.

The obtained capsule dispersion liquid was spray-dried to obtain powder capsules mainly consisting of mononuclear capsules.

Example 2 Hexamethoxyhexamethylolmelamine was added to a solution obtained by dissolving 20 parts of lauryl gallate and 10 parts of tribenzylamine in a mixed solution of 50 parts of di-ethyl adipate and 50 parts of di-n-butyl adipate. Methoxymethylolated melamine initial condensate (trade name: Cynull 350) containing as the main component
．． 42 parts of solids (manufactured by Mitsui Toatsu Chemical Co., Ltd.) were added and mixed to obtain an internal phase liquid.

Separately, in a stirring mixing vessel equipped with a heating device, 0.6 parts of an ethylene-maleic anhydride copolymer (trade name EMA-31, manufactured by Monsando) and an ethylene-maleic anhydride polymer copolymer (trade name EMA-31) were placed. -81° (manufactured by Monsando) 0.3
Aqueous solution prepared by heating and dissolving 300 parts of water was added, and a 5% aqueous solution of caustic soda was added to adjust the pH to 4°0.
Further, 0.6 part of funnel oil was added to prepare 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 was 5.0 μm.
The reaction was carried out at ℃ for 3 hours. Subsequently, this system was stirred for 0.00 min.
IN-hydrochloric acid was gradually added to adjust the pH of the system to 4.0, and the temperature of the system was further raised to 95°C and reacted at 95°C for 5 hours to obtain a milky white capsule dispersion. .

The resulting capsule dispersion was suction-filtered, and the paste was further dried to obtain powder capsules mainly consisting of mononuclear capsules. 5 parts of this powder capsule 3' and 5 parts of starch particles were dispersed in 60 parts of an acrylate photocurable resin (trade name: AROEX, manufactured by Toagosei Kagaku Kogyo Co., Ltd.) in which 0.2 part of benzoin ethyl ether was dissolved. Got the ink.

40g/r of the above capsule ink using a gravure printing machine
rr base paper was printed with an ink amount of 7 g/- and irradiated with ultraviolet rays to obtain a top paper.

Preparation of the bottom 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, add ferric chloride to 500 parts of water. After adding 108 parts of an aqueous solution under strong stirring to form yellow fine particles, 500 parts of a 20% aqueous solution of sodium t-butylbenzoate was added to this dispersion. Furthermore, 125 parts of TiC was gradually added to this dispersion under strong stirring to form 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 solid content of the above slurry, 20 parts of titanium oxide, 50 parts of aluminum hydroxide, and 710 parts of tribenzyl amine were added to the slurry. After adding and strongly dispersing, carboxy-modified styrene-butadiene copolymer latex (solid content concentration 50%) is added to the dispersion.
A coating liquid was obtained by adding 15 parts of .

Apply the obtained coating liquid to 40g/rrr base paper by 8g dry weight.
/rrr using an air knife coater to obtain a lower paper.

When the upper paper was superimposed on the lower paper and printed using a typewriter, extremely clear colored steps were obtained.

Example 3 Preparation of trimethylolmelamine 14.9 parts of a 37% formalin aqueous solution was diluted with water to give 10
After setting it to 0 copies, 0. P with I N -Na011 aqueous solution
I (adjusted to 6.5 to 6.8, and further added melamine to 23.1
of the mixture was added, and the temperature was gradually raised to 75° C. while stirring to completely dissolve the melamine. Next, the mixture was held at 75° C. for 5 minutes, then rapidly cooled to 0° C., stirring was stopped, and the mixture was allowed to stand for one day and night, and white crystals were precipitated.

The crystals were filtered, washed several times with methanol, and then air-dried to obtain 25.7 parts of trimethylolmelamine crystals.

Preparation of triethoxytrimethylolmelamine 25.7 parts of trimethylolmelamine and 300 parts of ethanol were added to a separable flask equipped with a reflux condenser, and while stirring at 78°C, 5 parts of 1N-HCl was added to crystallize trimethylolmelamine. was dissolved. After dissolution, the mixture was kept at 78°C for 30 minutes, and then 5 parts of 1N-Na0⁻ aqueous solution was added.

Next, this was cooled and filtered to remove trace impurities, and then 60 parts of this was concentrated at a temperature of 55°C, 30 parts of xylene was added thereto, and an additional 40 parts of it was concentrated to obtain triethoxytrimethylolmelamine. A xylene solution of was obtained.

Preparation of microcapsules The above melamine initial stage was added to a solution obtained by dissolving 20 parts of lauryl gallate and 5 parts of tribenzyl amici in a mixed solution of 50 parts of di-ethyl adipate and 50 parts of di-n-butyl adipate. The condensate was added and mixed to obtain an internal phase liquid.

Separately, 200 parts of a 1.0% aqueous solution of ethylene-maleic anhydride copolymer (trade name EMA-31, manufactured by Monosanto Co., Ltd.) was added to a stirring mixing container equipped with a heating device, and 5%
A caustic soda aqueous solution was added to adjust the pH to 5.0, and 0.5 parts of funnel oil was further added to prepare an aqueous medium for capsule production.

This aqueous medium was heated to 80°C, and the internal phase liquid was emulsified and dispersed therein so that the average particle size was 4.0μ.
The temperature was raised to 0°C and maintained at this temperature for 2 hours. Then,
The pH of the system was adjusted to 4.5 by gradually adding 0.1N-hydrochloric acid to this system while stirring, and then the temperature of the system was raised to 95°C, and the reaction was carried out at 95°C for 5 hours. A milky white capsule dispersion was obtained.

The obtained capsule dispersion liquid was spray-dried to obtain powder capsules mainly consisting of mononuclear capsules.

Example 4 25.7 parts of trimethylolmelamine, 11 parts of ethanol, and 300 parts of isopropyl alcohol were added to a separable flask equipped with a reflux condenser, and while stirring at 78°C, 0 parts of IN-HCl was added to the mixture. crystals were dissolved.

After dissolving and keeping at 78°C for 2 hours, I N -Na011
After adding 10 parts of the aqueous solution, cooling and filtering to remove trace impurities, 80 parts of the aqueous solution was concentrated at a temperature of 70°C, 30 parts of xylene was added, and an additional 40 parts of the di-ethoxy A xylene solution of an initial condensate containing mono-isopropoxytrimethylolmelamine as a main component was obtained.

msl! capsules were prepared in the same manner as in Example 3, except that the above melamine initial condensate was used. t. After that, powder capsules were obtained in the same manner.

Example 5 25.7 parts of trimethylolmelamine, 7.6 parts of methanol
300 parts of isopropyl alcohol and 300 parts of isopropyl alcohol were added to a separable flask equipped with a flow condenser, and while stirring at 64° C., 0 parts of 1N-HCl was added to dissolve the trimethylolmelamine crystals.

After dissolving and keeping at 64 °C for 1 hour, I N -NaO■
After adding 10 parts of the aqueous solution, cooling and filtering to remove trace impurities, 80 parts of the aqueous solution was concentrated at a temperature of 50°C, 30 parts of xylene was added, and an additional 40 parts of the dimethoxylene were concentrated. A xylene solution of mono-impropoxytrimethylolmelamine was obtained.

Example 6: Capsules were prepared in the same manner as in Example 3, except that the above melamine initial condensate was used, and powder capsules were obtained in the same manner thereafter. Example 6: 25.7 parts of trimethylolmelamine, 5.5 parts of ethanol
and 300 parts of isopropyl alcohol were added into a separable flask equipped with a reflux condenser, and while stirring at 78° C., 0 parts of 1N-HCl was added to melt the trimethylolmelamine crystals.

After dissolving and keeping at 78°C for 2 hours, I N -Na01l
After adding 10 parts of the aqueous solution, cooling and filtering to remove trace impurities, 80 parts of the aqueous solution was concentrated at a temperature of 70°C, 30 parts of xylene was added thereto, and an additional 40 parts of the monomer was concentrated. A xylene solution of ethoxy-di-isopropoxytrimethylolmelamine was obtained.

Capsules were prepared in the same manner as in Example 3 except that the melamine initial condensate was used, and powder capsules were obtained in the same manner thereafter.

Example 7 25.7 parts of trimethylolmelamine, 3.8 parts of methanol
and 300 parts of ethanol were added to a separable flask equipped with a reflux condenser, and the solution was heated to 1N while stirring at 64°C.
Five parts of HCl was added to dissolve the trimethylolmelamine crystals.

After melting and keeping at 64°C for 30 minutes, I N -NaOH
After adding 5 parts of an aqueous solution, cooling and filtering to remove trace impurities, 80 parts of the aqueous solution was concentrated at a temperature of 50°C, 30 parts of xylene was added thereto, and an additional 40 parts of the monomer was concentrated. A xylene solution of methoxy-di-ethoxytrimethylolmelamine was obtained.

Capsules were prepared in the same manner as in Example 3, except that the above melamine initial clamp was used, and powder capsules were obtained in the same manner thereafter.

Example 8 4 parts of crystal violet lactone was dissolved in 100 parts of alkylnaphthalene (trade name: KMC Oil, manufactured by Kureha Chemical Co., Ltd.), the resulting solution was adjusted to 70°C, and then hexamethoxyhexamethylolmelamine was dissolved as the main component. 63 parts of a solid methoxymethylolated melamine initial condensate (trade name Cynor 350, manufactured by Mitsui Toatsu Chemical Co., Ltd.) was added and mixed to obtain an internal phase liquid.

A capsule dispersion liquid was obtained in the same manner as in Example 2, except that the above-mentioned internal phase liquid was used, and powder capsules were obtained in the same manner.

Capsule ink was obtained by dispersing 35 parts of this powder capsule in 65 parts of microcrystalline wax having a melting point of 96°C and a penetration rate of 8. The obtained ink was printed on a 40 g/rd base paper using a hot melt coater at an ink amount of 1 g/rd to obtain a top paper.

Preparation of bottom paper 65 parts of aluminum hydroxide, 20 parts of zinc oxide, 3.5-
Mixture of zinc di(α-methylbenzyl)salicylate and α-methylstyrene/styrene copolymer (melt ratio 80/
20) Add 20 parts (solid content) of carboxy-modified styrene-butadiene copolymer latex to a dispersion obtained by grinding 15 parts of polyvinyl alcohol aqueous solution (solid content) and 300 parts of water in a ball mill for 24 hours. In addition, the prepared developer coating liquid was applied to 40 g/+1 paper using an air knife coater so that the solid content was 5 g/rrr to prepare a lower paper.

When the upper paper and lower paper prepared as described above were overlapped and printed using a typewriter, a clear colored image was obtained.

Comparative Example 1 4 parts of crystal violet lactone was mixed with 100 parts of alkylnaphthalene (trade name: KMC Oil, manufactured by Kureno\Chemical Co., Ltd.)
Aromatic polyvalent isocyanate (
Product name: Coronet)-L, manufactured by Nippon Polyurethane Co., Ltd.) 15
This solution was added to 200 parts of a 3% polyvinyl alcohol aqueous solution and emulsified to give an average particle size of 7 μm.
This system was reacted at 8.0°C for 4 hours to obtain a capsule dispersion.

The obtained capsule dispersion was spray-dried, but it turned out to be a huge*7"ゞ"' with a cluster form in which the capsules were fused together.
“Many 6 powders” 7” (=ztzLA゛4’+i
.

There wasn't.

Capsule ink was obtained by dispersing 35 parts of this powder capsule in 65 parts of microcrystalline wax with a melting point of 96°C and a penetration rate of 8, and coated with a true melt coating machine at 40 g/rr.
An upper paper was obtained by printing on a base paper of R at an ink amount of 7 g/rrr. .

When the upper paper prepared as described above and the lower paper were overlapped and printed using a typewriter, only an extremely unclear colored image was obtained.

Patent applicant Kanzaki Paper Co., Ltd.

Claims (1)

Scope of Claims: (11) A hydrophobic core material containing a melamine-formaldehyde resin initial condensate having a degree of formaldehyde substitution of 40 to 100%, a degree of alkylation of 80 to 100%, and a degree of hydrophobicity of 4 to 20. 1. A method for producing powder capsules, which comprises emulsifying them in a neutral medium to form a wall film under conditions that promote polycondensation to form a microcapsule dispersion, and then removing the dispersion medium. (2) The manufacturing method according to claim 11, wherein the melamine-formaldehyde resin initial condensate has a degree of hydrophobicity of 5 to 8. (3) The melamine-formaldehyde resin initial condensate is hexamethoxyhexamethylolmelamine. (4) The melamine-formaldehyde resin initial condensate is an initial condensate mainly composed of triethoxytrimethylolmelamine. The manufacturing method according to claim (2). (5) The conditions for promoting polycondensation include maintaining the reaction system at 80° C. or higher for 2 hours or more, and adjusting the pH with an acid at least once during the reaction. The manufacturing method according to claims Nos. ('') to (4). (6) A polymer emulsifier and a low molecular emulsifier are present in water or a hydrophilic medium for emulsifying the hydrophobic core substance. A manufacturing method according to claim (1).