JPH0459932B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a method for manufacturing microcapsules, and particularly to a method for manufacturing microcapsules having an amino resin wall. (Prior art) Microcapsules have the function of temporarily protecting the core substance, which is originally unstable as it is, making it stable, and releasing it instantly or gradually when necessary. It was developed by NCR Corporation in the United States in the early 1990s for carbonless paper, and has already been used in this field for over 30 years.
In recent years, the manufacturing technology of microcapsules has progressed significantly, and they are used in pharmaceuticals, pesticides, fragrances, cosmetics, foods,
Attempts have been made to apply it to dyes, etc., and it is now widely used in various fields as well as carbonless paper. In general, physical methods, mechanical methods, physicochemical methods, and chemical methods are known as methods for producing microcapsules, and they are appropriately selected and used depending on the purpose. With physical and mechanical methods, the particle size of the capsules obtained is large and the density of the wall membrane is insufficient, so the uses of microcapsules produced by these methods are limited. On the other hand, with physicochemical and chemical methods, it is easy to control the capsule particle size arbitrarily, particles as small as several micrometers can be easily produced, and capsules with highly dense wall membranes can be obtained. Used for a wide range of applications. As a physicochemical method, the coacervation method using gelatin as a membrane material is known and is currently applied in the widest range of fields, but it is expensive because it uses natural gelatin as a membrane material. Moreover, it has disadvantages such as being easily attacked by microorganisms, the water resistance of the produced capsules being poor, it being difficult to obtain a highly concentrated capsule slurry, and the encapsulation process being complicated. In addition, as a chemical method, an interfacial polymerization method is used in which a hydrophobic monomer and a hydrophilic monomer are polymerized at the interface between a hydrophobic core substance and an aqueous phase to form a wall film of polyamide, epoxy resin, polyurethane, polyurea, etc. and an in-situ polymerization method in which only one of the hydrophobic core material or the aqueous phase is subjected to a polymerization reaction to form a wall surface of an amino resin or the like around the core material. Interfacial polymerization method (for example, JP-A-49-25822, JP-A-52-48599, JP-A-54-91980, JP-A-56-
No. 78182, JP-A-56-88954, etc.) use highly reactive or highly toxic materials such as isocyanates, acid chlorides, and epoxy compounds as membrane materials, making it difficult to control the polymerization reaction and making it difficult to use active hydrogen. However, it has drawbacks such as the fact that it cannot be used as a core material, and the membrane material itself is expensive. On the other hand, in the in-situ polymerization method, most of the materials that form synthetic resins, such as acrylic ester resins, amino resins, and polyester resins, are used as membrane materials.
Among these, amino resins have advantages such as being cheap and easily available, not requiring a special catalyst during the polymerization reaction, and being able to carry out the polymerization reaction in a relatively short time. In this way, the in-situ polymerization method is easier to handle than the interfacial polymerization method, so it is more practical. 1978-
Many inventions have been filed, such as No. 84881 and JP-A-54-49984. However, although the capsule wall membrane obtained by this method has excellent water resistance, it has poor density and is difficult to sufficiently emulsify and disperse the core material. It has drawbacks such as difficulty in stably depositing it. The present invention relates to an encapsulation method using an in-situ polymerization method. The method of using melamine formaldehyde resin or urea formaldehyde resin as a membrane material is already known, as described in, for example, Japanese Patent Publications No. 37-12380, Japanese Patent Publication No. 3495-1982, and Japanese Patent Publication No. 23165-1974. However, as mentioned above, these methods have drawbacks such as it is difficult to efficiently and stably deposit the polycondensate of amino resin around the hydrophobic core material, and it is difficult to emulsify and disperse the core material sufficiently. It was hot. In order to improve these shortcomings, the Special Publication Showa 54-16949
JP-A-53-84881, JP-A-53-84882 and JP-A-53-84883 disclose ethylene/maleic anhydride copolymer and methyl vinyl ether as anionic polymer electrolytes used as system modifiers. / Methods using maleic anhydride copolymers, polyacrylic acid, etc. have been announced. This method improved the emulsification and dispersion of the hydrophobic core substance, improved the strength and density of the capsule wall membrane, and made it possible to obtain a highly concentrated capsule slurry in a short time, but the viscosity of the capsule slurry increased. Moreover, there are also drawbacks such as the fact that it takes a long time to dissolve particularly effective ethylene/maleic anhydride copolymers and methyl vinyl ether/maleic anhydride copolymers. Also, JP-A-54-49984, JP-A-55-47139
No. 55-15660 discloses a styrene/maleic anhydride copolymer or its combination with a vinyl acetate/maleic anhydride copolymer or an ethylene/maleic anhydride copolymer. This method further improves the emulsifying and dispersing properties of the core substance, resulting in a stable, low-viscosity, and high-concentration capsule slurry, but styrene/maleic anhydride copolymer precipitates when the pH is low. There is a drawback that it cannot be used in the urea-formaldehyde system, which is often subjected to polycondensation reaction, and it also has a drawback that it cannot be used in a residual formaldehyde removal method that removes unreacted residual formaldehyde at a low pH. Furthermore, in JP-A No. 56-51238, polyethylene sulfonic acid, which is an anionic polymer electrolyte, is added to the melamine formaldehyde system as a system modifier.
The use of styrene sulfonic acid polymers such as acrylic acid/styrene sulfonic acid copolymers has been announced. Since styrene sulfonic acid polymers are stable even at low pH, it has become possible to carry out polycondensation reactions using urea formaldehyde or to remove residual formaldehyde at low pH. However, styrene sulfonic acid polymers often foam when dissolved. There are problems with workability, and when used in a urea-formaldehyde system, the entire system condenses even with a slight change in reaction conditions. The present inventor previously announced the use of acrylic acids/acrylamide/acrylonitrile as a system modifier as a novel method for producing microcapsules (Japanese Patent Application No. 59-94629). According to this method, by using an acrylic acid/acrylamide/acrylonitrile terpolymer as a system modifier, a capsule slurry of good quality can be obtained in a short reaction time. (Problems to be Solved by the Invention) However, there has been a need for a method for producing microcapsule slurry of better quality, lower viscosity, and higher concentration. (Means for Solving the Problems) The present invention aims to improve the above-mentioned Japanese Patent Application No. 59-94629. The present inventors have discovered that (1) the hydrophobic core material has good emulsifying and dispersing properties, (2) the stability of the emulsion is maintained, (3) the encapsulation process is simple, and (4) the reaction time is short. (5) In order to establish a method for producing microcapsules that can obtain capsules with excellent wall strength, density, water resistance, and moisture resistance with lower viscosity and higher concentration. As a result of various studies, it was discovered that the above object could be achieved very effectively by using a terpolymer of acrylic acids, acrylonitrile, methacrylamide or dimethylacrylamide as a system modifier, and the present invention I was able to complete it. The method for producing microcapsules of the present invention involves emulsifying and dispersing a hydrophobic core substance in an acidic aqueous solution of an anionic polymer electrolyte, and then forming a capsule having an amino resin wall around the core substance. The production method is characterized by using an acrylic acid/acrylonitrile/metal acrylamide or dimethyl acrylamide terpolymer as the anionic polymer electrolyte, and adding a hydrophobic core substance to an acidic aqueous solution of the terpolymer. After emulsifying and dispersing the core material, a polycondensate of amino resin is formed and deposited around this core material to form a capsule wall membrane. Furthermore, compared to the -CONH ₂ groups of acrylamide used in Japanese Patent Application No. 59-94629, the -CONH ₂ groups of metalacrylamide or the -CON(CH ₃ ) ₂ groups of dimethylacrylamide are more methylol of the amino resin. Perhaps because the reaction with the group was surprisingly small, the viscosity of the system did not increase much, making it possible to produce capsule slurry with a much higher concentration. The method of the present invention is carried out mainly according to the following steps. That is, an acidic aqueous solution of an acrylic acid/acrylonitrile/methacrylamide or dimethylacrylamide terpolymer is prepared. If necessary, adjust the pH to within the acidic range. The hydrophobic core substance to be encapsulated is emulsified and dispersed in this aqueous solution. The amino compound, which is a capsule wall forming material, may be added either before or after emulsification and dispersion. The amino compound may be used after forming an initial condensate with the aldehyde to be added next. Examples of those that have already formed an initial condensate include melamine resin initial condensate aqueous solution (trade name: Milben Resin SM-800, manufactured by Showa Kobunshi Co., Ltd.);
Urea resin initial condensation aqueous solution (product name: Thermotite)
3HSP, manufactured by Showa Kobunshi Co., Ltd.), etc. If necessary
Adjust PH. Next, while stirring, aldehyde is added (addition of aldehyde is not necessary when using an amino resin initial condensate), and after raising the temperature, it is maintained for a certain period of time to form a capsule wall film. Thereafter, cooling and/or pH adjustment are performed as necessary to complete encapsulation. The acrylic acid/acrylonitrile/methacrylamide or dimethylacrylamide terpolymer used in the present invention preferably has a size of 50 to 200,000 cps, preferably 100 to 10,000 cps, when expressed in terms of the viscosity of an aqueous solution. However, the viscosity referred to here is determined by measuring the anionic terpolymer aqueous solution according to the present invention, which is usually obtained in an acidic state with a nonvolatile content of 15 to 25% by weight and a pH of usually 1 to 4, at 30°C using a B-type viscometer. This is the value measured. If the viscosity is less than 50 cps, the protective effect during emulsion dispersion and capsule formation will be insufficient,
If it is larger than 200,000 cps, it becomes difficult to handle and the resulting capsule slurry also has a high viscosity, which is generally not preferable. In addition, the copolymerization ratio of the terpolymer is preferably 55 to 95 mol% of acrylic acids, 2 to 20 mol% of acrylonitrile, and 2 to 30 mol% of methacrylamide or dimethylacrylamide.
Preferably, 60 to 90 mol% of acrylic acids, 6 to 15 mol% of acrylonitrile, and 4 to 25 mol% of methacrylamide or dimethylacrylamide are preferable. If the acrylic acid content is less than 55 mol%, emulsifying dispersion power and emulsified particle stability will be lacking, and if it is more than 95 mol%, the resulting capsule slurry will have a high viscosity. If the acrylonitrile content is less than 2 mol%, emulsifying dispersion power and particle stability will be lacking, and if it is more than 20 mol%, the terpolymer will become insoluble in water. Methacrylamide or dimethylacrylamide is 2
If it is less than 30 mol%, the emulsifying dispersion power will be lacking and the emulsification rate will be slow, so the encapsulation reaction will take time, and the efficiency of forming and depositing the amino resin around the core material will be poor, and if it is more than 30 mol%. In this case, the system during the encapsulation process tends to become unstable, and aggregation is likely to occur. Acrylic acids may remain as free acids,
Some of the carboxyl groups in the molecule may form a salt. Typical salts include, for example, sodium salts, potassium salts, and ammonium salts. Among acrylic acids, acrylic acid is particularly preferably used. The acrylic acid/acrylonitrile/methacryamide or dimethylacrylamide terpolymer used in the present invention can be prepared by, for example, adding these three monomers in water to hydrogen peroxide, potassium persulfate, ammonium persulfate, benzoyl peroxide, and cumene. It is prepared by methods known to those skilled in the art by radical polymerization with catalysts such as peroxide, cyclohexane peroxide, di-t-butyl peroxide, t-butyl hydroperoxide, methyl ethyl ketone peroxide, azobisisobutyronitrile, and the like. Note that when acrylonitrile has a high copolymerization ratio, a cloudy aqueous solution is sometimes obtained, but it can be used without any problem in producing the microcapsules, and the desired effect can be obtained. Further, the terpolymer can be mixed and dissolved in water at various ratios. The amount of the terpolymer used in the hydrophilic encapsulation medium is determined by the hydrophobic core material.
Generally, it is 1 to 30 parts by weight per 100 parts by weight, but the concentration, viscosity,
It is selected appropriately depending on the particle size of the capsule. However,
If the amount used is small, agglomeration will occur in the system during the encapsulation process, and if the amount used is too large, the viscosity of the resulting capsule slurry will increase, making it difficult to obtain good capsules, so the amount used is 3. ~25 parts by weight is preferred. The amino resin forming the capsule wall membrane is made of an amino compound selected from urea, methylol urea, thiourea, alkyl urea, ethylene urea, melamine, melol melamine, benzoguanamine, acetoguanamine, etc., formaldehyde, acetaldehyde, glutaraldehyde, It refers to a resin obtained by polycondensing an aldehyde selected from paraformaldehyde, crotonaldehyde, benzaldehyde, etc., and is used in the form of each monomer or desired condensate. The hydrophobic core substance to be encapsulated is
For example, fish oil, animal oils such as lard oil, soybean oil,
Vegetable oils such as linseed oil, peanut oil, castor oil, corn oil, petroleum, kerosene, gasoline,
Hydrophobic liquids such as mineral oils such as naphtha, paraffin oil, toluene, xylene, etc., synthetic oils such as alkyl-substituted diphenylalkanes, alkyl-substituted naphthalenes, diphenylethanes, dibutyl phthalate, methyl salicylate, etc. are used. These hydrophobic liquids can be used by appropriately mixing and dissolving medicines, agricultural chemicals, fragrances, foods, dyes, catalysts, etc., depending on the use and purpose of the microcapsules. The pH when emulsifying the hydrophobic core material in the encapsulating hydrophilic medium may be in the acidic range of 2 to 7.
For this purpose, adjust the pH using a suitable acid or alkali if necessary. Further, although it is not necessary to specify a particular temperature, it is generally preferable to adjust the temperature to 30 to 50°C, since the higher the temperature, the more uniform the particle size of the emulsified particles becomes. In the encapsulation reaction, it is desirable to adjust the reaction temperature to 30 to 100°C, preferably 40 to 95°C, especially 50 to 90°C, taking into account the polycondensation conditions of the amino resin.
°C is preferred. The time required for the reaction varies depending on various factors such as reaction volume and reaction container, but is usually 0.5~
It takes about 6 hours. Further, the pH of the system should be acidic, preferably adjusted to 1 to 6.5, particularly 2 to 5.5. At this time, in order to maintain the pH of the system acidic, for example, formic acid, acetic acid, citric acid, oxalic acid, etc.
Acid catalysts commonly used in the production of amino resins, such as hydrochloric acid, phosphoric acid, sulfuric acid, nitric acid, and ammonium chloride, can be used. You can also use it. In addition to the above-mentioned acids, a basic substance such as alkali metal hydroxide aqueous ammonia, triethanolamine, etc. can be used to separately adjust the pH to a desired level. The properties of the resulting capsule wall film depend on the encapsulation reaction conditions mentioned above, i.e. temperature, pH.
Or, because the temperature increase rate etc. have an extremely large effect,
Reaction conditions are appropriately set depending on the type of capsule wall-forming substance and the intended use of the capsule. Regarding stirring, it is preferable to carry out uniform stirring to the extent that foaming does not occur so as not to impair the quality of the obtained capsules. After holding for a certain period of time and completing encapsulation, as necessary, the pH of the system may be adjusted with a basic substance, or with sodium sulfite, formamide, hydroxylamine hydrochloride, etc.
Unreacted aldehyde remaining in the system is removed by adding chemicals such as urea or ethylene urea or by steam distillation. (Function) The acrylic acids/acrylonitrile/methacrylamide or dimethylacrylamide terpolymer according to the present invention can be easily produced as an aqueous solution, so it can be easily produced using conventional ethylene/maleic anhydride copolymers, methyl vinyl ether/maleic anhydride, etc. Unlike copolymers, there is no problem of requiring a long time for dissolution, and there is no foaming seen with styrene sulfonic acid polymers, so it has excellent workability. moreover,
Unlike styrene/maleic anhydride copolymer, urea formaldehyde resin, which cannot be produced with styrene/maleic anhydride copolymer, can be used as a wall film because it does not precipitate even in low pH ranges and can exist stably. It can be used in a method for producing microcapsules, and is also effective in a method for removing residual formaldehyde at a low pH. (Effects) Therefore, according to the present invention, an emulsion of a hydrophobic core substance that is stable and has a small and uniform particle size can be obtained in either case of melamine formaldehode type or urea formaldehyde type, and can be made in a short time. It promotes the formation of a highly dense capsule wall film efficiently, and capsules with excellent quality such as water resistance can be obtained with low viscosity and high concentration. Such excellent effects are due to the fact that the acrylic acid/acrylonitrile/methacrylamide or dimethylacrylamide terpolymer of the present invention itself has high emulsifying and dispersing power, has excellent protective colloid ability, and also has a high ability to absorb polycondensates of amino resins. It is thought that this is because it has the ability to efficiently form and deposit around the core substance, but its detailed function is not clear. Also, the acrylamide used in Japanese Patent Application No. 59-94629
Compared to _two CONH groups, methacrylamide has -
CONH ₂ groups or dimethylacrylamide -
The CON(CH ₃ ) ₂ groups reacted surprisingly little with the methylol groups of the amino resin, so the viscosity of the system did not increase much, making it possible to produce a capsule slurry with a much higher concentration. (Example) Hereinafter, the method of the present invention will be explained in more detail with reference to Examples. In the examples, the method of the present invention will be described for the case of carbonless paper, which is the most commonly used microcapsule, but the present invention is not limited to the examples only, and capsules for other uses can also be manufactured in the same way. I can do it. Further, unless otherwise specified, parts and percentages in the examples are each based on weight. Also PH
To prepare 10% sodium hydroxide aqueous solution and 10%
Although hydrochloric acid was used, the present invention is not limited thereto. Example 1 An anionic terpolymer aqueous solution was produced according to the following procedure. 608 parts of water was placed in a four-necked flask equipped with a stirrer, a thermometer, and a reflux condenser, and the temperature was raised to 80°C. 240 parts of acrylic acid aqueous solution (80%), acrylonitrile
Add 256 parts of water to 24 parts and 24 parts of methacrylamide,
A quarter of the homogeneous monomer aqueous solution was placed in a flask. Subsequently, 32 parts of a 1% aqueous solution of potassium persulfate was added. When the internal temperature of the flask rose to 88°C, the remainder of the monomer aqueous solution (3/4 of the total amount) was continuously dropped into the flask over 1.5 hours. After 30 minutes and 1 hour, add 8% of a 1% aqueous solution of potassium persulfate, respectively.
A total of 24 parts were added to the flask. The internal temperature of the flask was maintained at 85 to 88°C, and the above series of operations were performed in a nitrogen stream. It was then cooled. The analytical values of the obtained acrylic acid/acrylonitrile/methacryamide tricopolymer aqueous solution were as follows: non-volatile content: 21.7%, pH:
2.05, and the viscosity was 558 cps (30°C, B-type viscometer). An aqueous terpolymer polymer solution (copolymerization ratio: mol%, 78.2/13.4/8.4) with a nonvolatile content of 21.7% and consisting of 80 parts of acrylic acid, 10 parts of acrylonitrile, and 10 parts of methacrylamide obtained by the above method. 50 copies,
Add to 50 parts of water with stirring and adjust the pH to 4.5.
An encapsulated hydrophilic medium was obtained. On the other hand, melamine 10
25 parts of 87% formalin were added to 65 parts of water, the pH was adjusted to 9 under stirring, and when heated to 60°C, the mixture became transparent in about 20 minutes to obtain a melamine formaldehyde initial condensate. Separately, 4 parts of crystal violet lactone (CVL) and 2 parts of benzoyl leucomethylene blue (BLMB) were added to alkyl dipheniethane (trade name Hysol SAS-296, manufactured by Nippon Petrochemical Co., Ltd.).
Add 100 parts and heat and dissolve at 90℃ for 20 minutes with stirring.
It was cooled to room temperature to obtain a hydrophobic core material. 100 parts of this core material was added to 100 parts of the encapsulated hydrophilic medium at 40°C.
Mix at a temperature of
When the mixture was emulsified for 4 minutes at 9,000 rpm using a commercially available product (manufactured by Mimaki Co., Ltd.), an O/W type emulsion containing particles with an average particle size of 4.0 μm was obtained. After adjusting 100 parts of the melamine formaldehyde initial condensate prepared earlier to pH 4.5, it was heated to 40°C, added to this emulsion, and heated for 60 minutes while continuing to stir.
The temperature was raised to ℃. After holding for 2 hours, the temperature of the system was reduced to 25
Cool to ℃, adjust to PH8.5, average particle size 4.0μ,
A good capsule slurry with a viscosity of 180 cps (30°C, Type B viscometer) was obtained. Note that there was no particular foaming during the preparation of the encapsulated hydrophilic medium and during the encapsulation process, and the workability was good. Example 2 A commercially available aqueous solution of a melamine formaldehyde initial condensate (trade name: Milbenrange)
An encapsulation reaction was carried out in the same manner as in Example 1, except that SM-800 (manufactured by Showa Kobunshi Co., Ltd.) was used to produce a capsule slurry. The obtained capsule slurry had an average particle size of 3.8 μ and a viscosity of 170 cps (30
℃, B type viscometer) and was of good quality. Example 3 Acrylic acid 85 produced in the same manner as Example 1
part, 5 parts of acrylonitrile and methacrylamide
Consisting of 10 parts, non-volatile content 22.9%, viscosity 445 cps (30
℃, B-type viscometer), pH 2.85 terpolymer aqueous solution polymer (copolymerization ratio is 84.6/6.8/8.6 in mole%), and the initial commercialization as a melamine-formaldehyde initial condensate. A capsule slurry was produced by carrying out an encapsulization reaction in the same manner as in Example 1, except that an aqueous condensate solution (trade name: Milben Resin SM-800) was used. The obtained capsule slurry had an average particle size of 4.1 μ and a viscosity of 125 cps (30°C,
B-type viscometer) and was of good quality. Example 4 Acrylic acid 85 produced in the same manner as Example 1
10 parts acrylonitrile and 5 parts methacrylamide, nonvolatile content 23.2%, viscosity 837 cps (30
℃, B-type viscometer) and pH 2.50 of a terpolymer water-soluble polymer (copolymerization ratio is 82.6/13.3/4.1 in mol%). An encapsulation reaction was carried out in the same manner as in Example 1, except that an aqueous initial condensate solution (trade name Milben Resin SM-800) was used to produce a capsule slurry. The obtained capsule slurry had an average particle size of 4.2 μ and a viscosity of 190 cps (30
℃, type B viscometer), and was of good quality. Example 5 Acrylic acid 90 produced in the same manner as Example 1
1 part, 5 parts acrylonitrile, and 5 parts methacrylamide, non-volatile content 22.4%, viscosity 300 cps (30
℃, B-type viscometer) and pH 3.0 of a terpolymer water-soluble polymer (copolymerization ratio is 89.1/6.7/4.2 by mole). Except for using a condensate aqueous solution (trade name Milben Resin SM-800).
An encapsulation reaction was carried out in the same manner as in Example 1 to produce a capsule slurry. The obtained capsule slurry had an average particle size of 3.9μ and a viscosity of 220cps (30℃,
B-type viscometer) and was of good quality. Example 6 Acrylic acid 70 produced in the same manner as Example 1
parts, 10 parts of acrylonitrile and methacrylamide
Consisting of 20 parts, non-volatile content 22.7%, viscosity 644 cps (30
℃, B-type viscometer), pH 3.50 terpolymer aqueous solution polymer (copolymerization ratio is 69.1/13.6/17.1 in mol%)
The encapsulation reaction was carried out in the same manner as in Example 1, except that an aqueous solution was used and a commercially available aqueous solution of the initial condensate (trade name Milben Resin SM-800) was used as the melamine formaldehyde initial condensate. was manufactured. The obtained capsule slurry has an average particle size of 4.2μ and a viscosity of 140cps.
(30°C, Type B viscometer) and was of good quality. Example 7 Acrylic acid 80 produced in the same manner as Example 1
parts, 10 parts of acrylonitrile and 10 parts of N,N-dimethylacrylamide, nonvolatile content 22.0%,
Terpolymer water-soluble polymer with a viscosity of 305 cps (30°C, B-type viscometer) and a pH of 2.75 (copolymer ratio is in mol%)
79.3/13.6/7.1) The encapsulation reaction was carried out in the same manner as in Example 1, except that an aqueous solution was used.
A capsule slurry was produced. The obtained capsule slurry had an average particle size of 4.2 μ and a clay of 120 cps (30°C, B
type viscometer) and was of good quality. Example 8 Acrylic acid 80 produced in the same manner as Example 1
parts, 10 parts of acrylonitrile and 10 parts of N,N-dimethylacrylamide, nonvolatile content 22.0%,
A terpolymer aqueous solution polymer with a viscosity of 305 cps (30°C, B-type viscometer) and a pH of 2.75 (copolymer ratio is in mol%).
79.3/13.6/7.1) The use of an aqueous solution and a commercially available initial condensate aqueous solution (trade name Milbenresin SM-800) as a melamine formaldehyde initial condensate.
An encapsulation reaction was carried out in the same manner as in Example 1, except that a capsule slurry was produced. The obtained capsule slurry has an average particle size
It was of good quality, with a viscosity of 3.8μ and a viscosity of 140 cps (30°C, B-type viscometer). Example 9 Acrylic acid 70 produced in the same manner as Example 1
10 parts of acrylonitrile and 20 parts of N,N-dimethylacrylamide, non-volatile content, 22.6 parts.
%, viscosity 590 cps (30°C, B-type viscometer), PH3.30 terpolymer water-soluble polymer (copolymerization ratio is mol%)
71.3/14.0/14.7) aqueous solution was used, and a commercially available initial condensate aqueous solution (trade name Milbenresin SM-
A capsule slurry was produced by carrying out an encapsulation reaction in the same manner as in Example 1, except that 800) was used. The obtained capsule slurry had an average particle size of 4.0 μm and a viscosity of 110 cps (30° C., B-type viscometer), and was of good quality. Example 10 Acrylic acid 60 produced in the same manner as Example 1
10 parts of acrylonitrile and 30 parts of N,N-dimethylacrylamide, 22.7% non-volatile matter,
Terpolymer water-soluble polymer with a viscosity of 560 cps (30°C, B-type viscometer) and a pH of 3.65 (copolymerization ratio is 62.9/mole%)
The encapsulation reaction was carried out in the same manner as in Example 1, except that an aqueous solution (14.4/22.7) was used and a commercially available aqueous initial condensate solution (trade name Milben Resin SM-800) was used as the melamine formaldehyde initial condensate. A capsule slurry was produced. The obtained capsule slurry had an average particle size of 4.1μ,
The viscosity was 155 cps (30°C, B-type viscometer) and was of good quality. Example 11 Acrylic acid with non-volatile content of 21.7% obtained in Example 1/
Acrylonitrile/methacrylamide terpolymer aqueous solution 50 parts of polymer aqueous solution was added to 50 parts of water with stirring. Furthermore, 10 parts of urea and 1.4 parts of resorcin were added and dissolved. The pH of this water-soluble polymer aqueous solution containing urea and resilcin was adjusted to 3.5 to obtain an encapsulated hydrophilic medium. Separately CVL4 and BLMB2
The part is alkyldiphelethane (trade name: Hysol)
In addition to 100 copies of SAS-296 (manufactured by Nippon Petrochemical Co., Ltd.),
The mixture was heated and dissolved at 90°C for 20 minutes with stirring, and then cooled to room temperature to obtain a hydrophobic core material. When 100 parts of this core material was mixed with 100 parts of the encapsulated hydrophilic medium at a temperature of 45°C and emulsified for 4 minutes at 9000 rpm using a homo mixer (manufactured by Tokushu Kika Kogyo Co., Ltd.), the average particle size was An O/W emulsion containing particles with a diameter of 4.1 μm was obtained. Next, 27 parts of 37% hornmarin was added, and the temperature was raised to 60°C while stirring. After carrying out the encapsulation reaction at 60℃ for 2 hours, the temperature of the system was cooled to 20℃, and the pH was adjusted.
8.5 and produced a capsule slurry. The obtained capsule slurry had an average particle size of 4.1μ and a viscosity of
The value was 210 cps (30°C, B-type viscometer) and was of good quality. Example 12 A commercially available aqueous solution of an initial condensate as a urea-formaldehyde initial condensate (trade name: Thermotite 3HSP,
Example 11, except that the material (manufactured by Showa Kobunshi Co., Ltd.) was used.
An encapsulation reaction was carried out in the same manner as above to produce a capsule slurry. The obtained capsule slurry had an average particle size of 3.9 μm and a viscosity of 95 cps (30° C., B-type viscometer), and was of good quality. Example 13 Acrylic acid 80 produced in the same manner as Example 1
parts, 10 parts of acrylonitrile and 10 parts of N,N-dimethylacrylamide, nonvolatile content 22.0%,
Terpolymer water-soluble polymer with a viscosity of 305 cps (30°C, B-type viscometer) and a pH of 2.75 (copolymer ratio is in mol%)
79.3/13.6/7.1) The encapsulation reaction was carried out in the same manner as in Example 11, except that an aqueous solution was used.
A capsule slurry was produced. The obtained capsule slurry had an average particle size of 4.0 μm and a viscosity of 130 cps (30°C, B
type viscometer) and was of good quality. Example 14 Consisting of 80 parts of acrylic in the longitudinal direction produced in the same manner as in Example 1, 10 parts of acrylonitrile, and 10 parts of N,N-dimethylacrylamide, with non-volatile components.
22.0%, viscosity 305cps (30℃, B type viscometer), PH2.75
terpolymer water-soluble polymer (copolymerization ratio is mol%)
Example 79.3/13.6/7.1) except that an aqueous solution was used and a commercially available aqueous initial condensate solution (trade name Thermotite 3HSP, manufactured by Showa Kobunshi Co., Ltd.) was used as the urea formaldehyde initial condensate. An encapsulation reaction was carried out in the same manner as in 11 to produce a capsule slurry. The obtained capsule slurry had an average particle size of 3.8 μ and a viscosity of 100 cps (30°C, B-type viscometer).
It was of good quality. Comparative Example 1 Acrylic acid 50 produced in the same manner as Example 1
parts, 40 parts of cacrylamide and 10 parts of acrylonitrile
20.9% non-volatile content, viscosity 820cps (30℃,
B-type viscometer), a terpolymer water-soluble polymer with a pH of 8.65 (copolymerization ratio 48.0/38.9/13.1) was used, and a commercially available initial condensate as a melamine-formaldehyde initial condensate. Except for using an aqueous solution (trade name Milben Resin SM-800).
An encapsulation reaction was carried out in the same manner as in Example 1 to produce a capsule thriller. The obtained capsule slurry had an average particle size of 4.1 μ and a clay content of 430 cps (30°C,
B type viscometer). Comparative Example 2 Acrylic acid 80 produced in the same manner as Example 1
1 part and 20 parts methacrylamide, non-volatile content
22.9%, viscosity 650cps (30℃, B type viscometer), PH3.55
Copolymer water-soluble polymer (copolymerization ratio is mol%)
The encapsulation reaction was carried out in the same manner as in Example 1, except that an aqueous solution (82.5/17.5) was used and a commercially available aqueous initial condensate solution (trade name Milben Resin SM-800) was used as the melamine formaldehyde initial condensate. , produced a capsule slurry. The obtained capsule slurry had an average particle size of 4,
7 μ, viscosity 450 cps (30° C., B-type viscometer), but moisture resistance was poor. Comparative Example 3 Comprised of 10 parts of acrylonitrile and 90 parts of methacrylamide produced in the same manner as in Example 1, non-volatile content 21.8%, viscosity 470 cps (30°C, B-type viscometer),
We used an aqueous solution of a copolymer water-soluble polymer with a pH of 12.1 (copolymerization ratio 15.1/84.9 in mol%) and a commercially available aqueous solution of an initial condensate (trade name Milbenresin-800) as an initial condensate of melamine formaldehyde. An attempt was made to carry out the encapsulation reaction in the same manner as in Example 1, except that the encapsulation reaction was carried out in the same manner as in Example 1, but as soon as the pH of the water-soluble polymer aqueous solution was adjusted to the acidic side, agglomeration occurred, making it impossible to produce a capsule slurry. It was hot. Comparative Example 4 Acrylic acid 90 produced in the same manner as Example 1
1 part and 10 parts acrylonitrile, non-volatile content
19.3%, viscosity 900cps (30℃, B type viscometer), PH2.35
Copolymer water-soluble polymer (copolymerization ratio is mol%)
The encapsulation reaction was carried out in the same manner as in Example 1, except that an aqueous solution (86.9/13.1) was used and a commercially available aqueous initial condensate solution (trade name Milben Resin SM-800) was used as the melamine formaldehyde initial condensate. However, the hydrophobic core substance could not be emulsified and a capsule slushie could not be produced. Comparative Example 5 Acrylic acid 80 produced in the same manner as Example 1
and 20 parts of dimethylacrylamide, non-volatile content 24.5%, viscosity 415 cps (30°C, Type B viscometer),
The use of an aqueous solution of a water-soluble copolymer with a pH of 3.8 (copolymerization ratio of 84.6/15.4 in mol%) and a commercially available aqueous solution of an initial condensate as a melamine formaldehyde initial condensate (trade name: Milbenresin SM-800)
An attempt was made to carry out the encapsulation reaction in the same manner as in the example except for using the following method, but the entire system agglomerated during the reaction and no capsules were obtained. Comparative Example 6 Non-volatile content 22.3 produced in the same manner as Example 1
%, viscosity 760 cps (30°C, Type B viscometer), pH 1.80 polyacrylic acid aqueous solution was used, and a commercially available initial condensate aqueous solution (trade name Milben Resin SM-800) was used as a melamine formaldehyde initial condensate. The encapsulation reaction was carried out in the same manner as in Example 1 except for the above, but the entire system agglomerated during the reaction and no capsules were obtained. Comparative Example 7 Ethylene/maleic anhydride copolymer (trade name EMA31,
Monsanto Co., Ltd.) was dissolved in 80 parts of water to make an aqueous solution with a non-volatile content of 20%.
A capsule slurry was produced by carrying out an encapsulation reaction in the same manner as in Example 1, except that 800) was used. The resulting capsule slurry had a high viscosity, with an average particle size of 5.3 μm and a viscosity of 2000 cps (30° C., B-type viscometer). Further, it took a long time of 3 hours at 80°C to dissolve the ethylene/maleic anhydride copolymer. Comparative Example 8 Partial sodium salt of polystyrene sulfonic acid (trade name) as anionic polymer electrolyte aqueous solution
VERSA TL500, manufactured by National Starch) 20
except that an aqueous solution with a nonvolatile content of 20% was obtained by dissolving 1 part in 80 parts of water, and a commercially available aqueous solution of an initial condensate (trade name: Milben Resin SM-800) was used as an initial condensate of melamine formaldehyde. An encapsulation reaction was carried out in the same manner as in Example 1 to produce a capsule slurry. The obtained capsule slurry has an average particle size of 5.4μ and a viscosity of 2500cps.
(30℃, Type B viscometer).
Further, a large amount of foaming was observed during dissolution of a portion of the sodium salt of polyethylene sulfonic acid, so encapsulation was performed after leaving the solution for about 1 hour until the foam disappeared. Comparative Example 9 Partial sodium salt of polystyrene sulfonic acid (trade name) as anionic polymer electrolyte aqueous solution
The encapsulation reaction was carried out in the same manner as in Example 11, except that 20 parts of VERSA TL500) were dissolved in 80 parts of water to make an aqueous solution with a non-volatile content of 20%. The inside agglomerated and no capsules could be obtained. The capsule slurries obtained in the above Examples and Comparative Examples were evaluated for their various properties with respect to the following items. (1) Average particle system: The particle size distribution of the capsules was measured using a TA-type particle size analyzer (manufactured by Coulter Electronics), and the particle size at 50% volume point was shown as the average particle size. It is considered that the smaller the average particle size, the stronger the emulsifying power. (2) Viscosity: The viscosity of the capsule slurry at 30°C was measured using a B-type viscometer at 60 rpm. (3) Encapsulation rate: What is the encapsulation rate here?
It refers to the evaluation of the degree of color development on the coated surface after coating the capsule slurry on a carbonless base paper (color developer coated surface) and drying it. That is, for example, water is added to 50 parts of the obtained capsule slurry.
Add 50 parts and apply it to a commercially available carbonless base paper (product name Micro Chemical Paper NW40C, manufactured by Daio Paper Co., Ltd.) so that the dry coating amount is 4 g / m ² , and after drying, the coated surface I compared the colors. If the coated surface is pure white (good encapsulation rate), all the core substance has been encapsulated, but if the coated surface turns blue (poor encapsulation rate), emulsification and dispersion in the capsule slurry is insufficient. This means that there is a core substance that remains unencapsulated or a core substance that remains unencapsulated. That is, the encapsulation rate is one of the measures of the emulsifying and dispersing power of the system modifier. (4) Color development: Add 50 parts of water to 50 parts of capsule slurry, and further mix and disperse 5 parts of cellulose powder and 10 parts of 10% oxidized starch aqueous solution to adjust the capsule color. This capsule color was applied to a 40 g/m ² base paper using a wire bar to a dry coating amount of 4 g/m ² and dried to produce a carbonless top paper. Use this top paper as a commercially available bottom paper (product name: Micro Chemical Paper NW40C).
The images were superimposed and printed on a typewriter to evaluate color development. (5) Pressure smudge stain: Prepare the upper paper in the same manner as for the color development test, overlap it with the commercially available lower paper (product name: Micro Chemical Paper NW40C), apply static pressure of about 1.5 kg/cm ² , The color development stains on the developer surface of the lower paper were compared. Naturally, if the capsule film strength is weak or if the capsule particle size distribution is poor and there are coarse particles, the amount of colored stains will increase. (6) Humidity resistance: Prepare the top paper in the same way as for the color development test, leave it for one week in constant temperature and humidity conditions at 40℃ and 90% relative humidity. Chemical paper NW40C)
This was superimposed and printed using a typewriter, and compared with what was printed during the color development test. If the moisture resistance is poor, the color density will be lower than that printed during the color development test, and the difference between the two will become larger.
As the moisture resistance improves, the difference disappears, and it can be said that the capsule is good. The results of the above evaluation are summarized in Table 1 below.

【table】

[Table] (Note) The evaluation criteria in the table are as follows.
◎ mark…extremely good ○ mark…good
△ mark...Poor As is clear from Table 1 above, all of the capsules according to the present invention have a small average particle size of 3.8 to 4.2μ, and the viscosity of the capsule slurry is as low as 220 to 440 cps, resulting in an excellent encapsulation rate. The capsules had good color development and moisture resistance, and were of good quality with little color staining due to pressure. On the other hand, the average particle size of capsules according to comparative examples, except for comparative example 1, was
It is large (4.7μ or more), the viscosity of the capsule slurry is high, the moisture resistance is poor, and there is a lot of color staining due to pressure.
It could not be said to be of good quality. In addition, in Comparative Examples 3, 4, 5, 6, and 9, the entire system agglomerated during the encapsulation process, or the hydrophobic core substance could not be emulsified, making it impossible to produce mictocapsules. Nakatsuta. Comparative Example 1 is an example described in Japanese Patent Application No. 59-94629, but the viscosity of the capsule cellarry was lower than that of the example of the present invention.
It is as high as 430cps. Therefore, the present invention can produce microcapsules that are excellent in all properties and is extremely useful industrially.

Claims (1)

[Claims] 1. A method for producing microcapsules in which a hydrophobic core substance is emulsified and dispersed in an acidic aqueous solution of an anionic polymer electrolyte, and then a capsule having an amino resin wall is formed around the core substance. A method for producing microcapsules, wherein the anionic polymer electrolyte is an anionic terpolymer water-soluble polymer composed of acrylic acids, acrylonitrile, and methacrylamide or dimethylacrylamide. 2. The method for producing microcapsules according to claim 1, wherein the amino resin is a melamine formaldehyde resin. 3. The method for producing microcapsules according to claim 1, wherein the amino resin is a urea formaldehyde resin. 4. In the method for producing microcapsules according to claim 1, the anionic terpolymer water-soluble polymer contains 55 to 95 mol% of acrylic acids, 2 to 20 mol% of acrylonitrile, and methacrylamide. Alternatively, a method for producing microcapsules containing 2 to 30 mol% of dimethylacrylamide. 5. In the method for producing microcapsules according to claim 1, the anionic terpolymer water-soluble polymer is added to 100 parts by weight of the hydrophobic core substance,
A method for producing microcapsules containing 1 to 30 parts by weight. 6. In the method for producing microcapsules according to claim 1, the acidic aqueous solution of the anionic terpolymer water-soluble polymer has a viscosity of 50 to
A method for manufacturing microcapsules that is 200000cps. 7 In the method for producing microcapsules according to claim 6, the acidic water-soluble viscosity of the anionic terpolymer water-soluble polymer is 100 to
A method for manufacturing microcapsules that is 10000CPS.