JP2006007017A - Microcapsule - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a microcapsule having high emulsion dispersibility, appropriately large particle sizes with uniform distribution of the sizes and excellent strength, compactness and resistance to water, heat and hot humidity. <P>SOLUTION: A method of manufacturing the microcapsule comprises emulsion-dispersing an oily core substance in an acidic aqueous solution of an anionic polymer electrolyte and forming the membrane wall of the capsule by the hardening reaction of the initial condensate of melamine with formaldehyde. The anionic electrolyte is a copolymer obtained by polymerizing, in aqueous solution, a mixture of unsaturated monomers comprising (1) (a) a polymerizable unsaturated monomer having a carboxyl group, (2) (b) (meth)acrylonitrile, (c) methyl methacrylate, (d) a polymerizable unsaturated monomer having an amide group and/or (e) a polymerizable unsaturated monomer having a hydroxyl group, (3) (f) methacryloylpolyoxyethylene acid phosphate and/or (g) methacryloylpolyoxypropylene acid phosphate and (4) (h) polyethylene glycol monomethacrylate and/or (i) polypropylene glycol monomethacrylate. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a microcapsule. More specifically, the present invention relates to a microcapsule produced from a cured film of an initial condensate of melamine and formaldehyde, which has a good emulsifying dispersibility of the oily core material, a stable emulsion, and a high-concentration, low-viscosity slurry. The resulting microcapsules have an appropriate particle size, a uniform distribution, excellent strength, denseness, water resistance, heat resistance, temperature and humidity resistance, a simple manufacturing process, and an oily core substance. In contrast, the present invention relates to a microcapsule excellent in economic efficiency in which the use ratio of the emulsified dispersion resin liquid is small.

  The function of the microcapsule is to confine the core material in a minute spherical capsule, protect it without alteration, and release the core material by releasing it slowly or as needed at the time of its application. The performance of this is demonstrated.

  Today, microcapsules have a very wide range of applications, such as pressure-sensitive recording materials such as carbonless paper, pharmaceuticals, agricultural chemical sustained release agents, fragrances, adhesives, foods, detergents, dyes, catalysts, enzymes, rust inhibitors, etc. There are a wide variety. For example, specifically, in a microcapsule having a fragrance as a core material, a soybean oil solution of hinokitiol is encapsulated, a synthetic resin emulsion such as acrylic is used as a binder, and the resin is processed into a sheet or a yukata. There are practical applications such as manufacturing, use for automobile interior, spraying on special nonwoven fabric, and application for deodorant insole of shoes. In addition, to prevent erosion by moths and pests, drugs such as moth repellents and pest repellents are encapsulated and kneaded into electric wires and rubber tubes. For adhesive applications, for example, solvent-based epoxy resin adhesives and adhesives are encapsulated, applied to adherends such as bolts, and when applied, the capsules are broken by mechanical pressure and become strong. In some cases. Furthermore, there are also applications such as encapsulating dyes and temperature indicating agents to photochromic agents and temperature indicating agents.

  Among these uses, carbonless paper that is used most industrially is used for courier services and various slips. In this case, the microcapsule is destroyed by the writing pressure applied to the upper sheet, and the dye contained in the capsule reacts with the developer applied to the lower sheet to develop a color. . Therefore, the microcapsule has a dense film wall, strength, heat resistance, no change over time at high temperature and humidity, the capsule does not break at the friction level of paper, breaks at writing pressure, and has good color development. It is required to be. The particle size is preferably about 4 to 7 microns, and the distribution is required to be uniform. Small capsules of 2 microns or less are not destroyed by the pen pressure and are wasted, resulting in economic problems. Capsules larger than 7 microns are not preferable because they are fragile and cause bleeding and contamination.

  Microcapsule production methods include physical methods, mechanical methods, physicochemical methods, and chemical methods.

    The physical or mechanical method requires special equipment, and the resulting capsule has a particle size that is too large, such as several tens of microns. There is a weak point that the use is considerably limited due to the drawback that the substance easily leaks over time.

    The physicochemical method and chemical method do not require special equipment, the microcapsules have a particle size of 1 micron or less, can be easily controlled from small to several millimeters, and can be manufactured. It is used in many fields because of its advantages such as obtaining high performance.

    Historically, the gelatin / gum arabic method, which is well known as a coacervation (phase separation) method, is the most widely used physicochemical method. However, various problems such as spoilage, aggregation and economy due to the use of a natural product as a film agent and performance problems due to poor water resistance, and industrially, the solid content of microcapsules obtained by this method In applications where the concentration is low, especially when applied to a paper substrate such as carbonless paper, waste of drying energy is large, which is uneconomical and has a great difficulty in practical use.

    Chemical methods include interfacial polymerization, in which a monomer is polymerized at the interface between the oily core material and the aqueous phase to form a membrane wall, and in-situ polymerization in which only one of the oily core material or the aqueous phase is polymerized to form the membrane wall. There is legal.

  The interfacial polymerization method has long been represented by JP-A-49-25822. In this method, poval is used as an emulsifying dispersant, and the oily core material is first emulsified and dispersed in the aqueous phase. As the curing agent for forming the film wall, a highly reactive compound such as isocyanate, acid chloride, or epoxy compound is used. Therefore, the microcapsule film is tougher than the coacervation method, but it is difficult to control the polymerization reaction. . In addition, the core material having highly reactive active hydrogen cannot be used because it immediately causes reaction and gelation, and has a drawback that it is highly toxic and expensive.

  On the other hand, in the in-situ polymerization method, a water-soluble anionic polymer electrolyte is used as an emulsifying dispersant, and an amino resin such as a melamine resin is used as a curing agent for forming a membrane wall. It has the advantage that it is inexpensive, does not require a special catalyst for the polymerization reaction, and can easily produce microcapsules in a short time. Many patents have been filed for a long time. However, in this method, the emulsified dispersion of the oily core substance, the denseness of the membrane wall, etc. are worse than the other methods, and it is necessary to devise. Many of the patents have struggled to devise a resin composition of a polymer electrolyte, which is an emulsifying dispersant, in order to overcome these drawbacks. As the curing agent, an amino resin is used, and a melamine resin is mainly used. Although it is possible to use urea resin, the system must be made to have a considerably low pH in order to cure it, and problems such as corrosion and the curing reaction are too fast, and the resulting film wall is hard and brittle. Cheap. Therefore, in practice, a melamine resin that can easily control the curing reaction and obtain a tough film wall is mainly used.

  In the in-situ polymerization method, various contrivances have been made in order to overcome the above-mentioned drawbacks, and many improvements have been proposed. Usually, the above disadvantages are often solved by devising an emulsifying dispersant rather than a curing agent, and most past patents are concentrated on the resin composition of the emulsifying dispersant.

  For example, Japanese Patent Publication No. 54-16949 reports an ethylene / maleic anhydride copolymer as an anionic polymer electrolyte used for emulsifying and dispersing an oily core material. Melamine resin is used as the curing agent. By this method, the emulsifying dispersibility of the oily core substance was improved, the strength and denseness of the capsule membrane wall were improved, and the heat resistance and moisture resistance were also improved. However, the viscosity of the capsule slurry is high, the solubility of the ethylene / maleic anhydride resin in water is poor, and the workability is difficult.

  JP-A-54-49984 reports a styrene / maleic anhydride copolymer as an emulsifying dispersant. In this method, the emulsifying dispersibility of the oily core substance is further improved, and a stable and low-viscosity capsule slurry can be obtained. Although the strength of the film wall is sufficient, the styrene / maleic anhydride copolymer has a low pH, poor solubility in water, and has a defect of precipitation.

  JP-A-56-51238 reports styrene sulfonic acid polymers such as polystyrene sulfonic acid as an emulsifying dispersant. Styrene sulfonic acid polymer is stable even at low pH and has good wall film strength, heat resistance, and moisture resistance, but has high foamability when emulsified and dispersed slurry and melamine resin are cured, and there are difficulties in workability. On the other hand, the coating film applied to paper and the like repels due to foaming, resulting in coating unevenness, and there is a difficulty in commercialization.

Further, in Japanese Patent Publication No. 2634836, by using a terpolymer of acrylic acid, acrylonitrile and acid phosphooxypolyethylene glycol methacrylate as a system modifier, (1) emulsification dispersion of a hydrophobic core substance (2) and maintaining the stability of the emulsion, (3) the encapsulation process is simple, (4) and by a short reaction, (5) unrivaled strength, denseness, water resistance, moisture resistance It has been reported that a method for producing microcapsules capable of obtaining capsules having excellent properties with lower viscosity and higher concentration has been established. About description of said (1)-(5), the microcapsule as described is obtained by using a melamine initial stage condensate as a hardening | curing agent. However, the particle size of the emulsified dispersed particles and the finally obtained microcapsules is slightly small, for example, when applied to carbonless paper, the color developability is insufficient, and the particle size distribution is wide, especially those with small particle sizes. The capsules were not destroyed, and therefore, the color was not generated and wasted, which was problematic in terms of economy. In addition, a large number of particles having a large particle size were included, sometimes bleeding and causing contamination. Furthermore, if the terpolymer copolymer has a weak emulsifying and dispersing property with respect to the hydrophobic core material, and the terpolymer has a small proportion of use with respect to the hydrophobic core material, the emulsifying dispersion will not be successful and the oil may float on the surface. In extreme cases, the capsule slurry tended to separate. Therefore, in order to produce a stable microcapsule, the usage ratio of the terpolymer must be increased with respect to the hydrophobic core material, which has a disadvantage in terms of economy.
JP 49-25822 A Japanese Patent Publication No.54-16949 JP 54-49984 A JP-A-56-51238 Japanese Patent Publication No. 2634836

  The object of the present invention is to obtain a slurry having a high concentration and a low viscosity in a microcapsule produced from a cured film of an initial condensate of melamine and formaldehyde, having a good emulsifying and dispersing property of the oily core substance, a stable emulsion, and a high concentration and low viscosity. The particle size of the microcapsules is moderately distributed, the distribution is uniform, and the strength, denseness, water resistance, heat resistance, temperature and humidity resistance are excellent, the manufacturing process is simple and economical. The object is to provide excellent microcapsules.

  As a result of intensive studies to achieve the above object, the present inventors have found that an anionic polymer electrolyte obtained by aqueous copolymerization of a monomer mixture having a specific composition can achieve the above object, The present invention has been completed.

  That is, the first of the present invention is the production of a microcapsule in which an oily core substance is emulsified and dispersed in an acidic aqueous solution of an anionic polymer electrolyte and then a capsule membrane wall is formed by a curing reaction of an initial condensate of melamine and formaldehyde. In the method, the anionic polymer electrolyte comprises (1) a carboxyl group-containing polymerizable unsaturated monomer (a) and (2) (meth) acrylonitrile (b) and / or methyl methacrylate (c) and / or an amide # group. -Containing polymerizable unsaturated monomer (d) and / or hydroxyl group-containing polymerizable unsaturated monomer (e) and (3) methacryloyl polyoxyethylene acid phosphate (f) and / or methacryloyl polyoxypropylene acid phosphate (g) ) And (4) polyethylene glycol monomethacrylate (h) and / or polypropylene glycol monomethacrylate (i The present invention provides a microcapsule characterized by being a copolymer obtained by polymerizing an unsaturated monomer mixture comprising

  According to a second aspect of the present invention, in the first microcapsule of the present invention, the anionic polymer electrolyte is 1) a carboxyl group-containing polymerizable unsaturated monomer (a) and (2) (meth) acrylonitrile (b) and / or Methyl methacrylate (c) and / or amide # group-containing polymerizable unsaturated monomer (d) and / or hydroxyl group-containing polymerizable unsaturated monomer (e) and (3) methacryloyl polyoxyethylene acid phosphate (f) And / or an anionic polymer electrolyte composition comprising methacryloyl polyoxypropylene acid phosphate (g) and (4) polyethylene glycol monomethacrylate (h) and / or polypropylene glycol monomethacrylate (i).

  According to a third aspect of the present invention, in the first microcapsule of the present invention, the anionic polymer electrolyte comprises (1) a carboxyl group-containing unsaturated monomer (a) and a copolymer component (a), (b). , (C), (d), (e), (f), (g), (h) and (i) with respect to a total of 100 parts by weight, 60 to 95 parts by weight, (2) (meth) acrylonitrile ( Component b) and / or methyl methacrylate (c) and / or amide # group-containing polymerizable unsaturated monomer (d) and / or hydroxyl group-containing polymerizable unsaturated monomer (e) , (B), (c), (d), (e), (f), (g), (h) and (i) with respect to 100 parts by weight of the total, 2 to 20 parts by weight, (3) methacryloyl Polyoxyethylene acid phosphate (f) and / or methacryloyl polyoxypropylene acid phosphate Fate (g) is a total of 100 weights of copolymer components (a), (b), (c), (d), (e), (f), (g), (h) and (i) 0.5 to 12 parts by weight with respect to parts, (4) polyethylene glycol monomethacrylate (h) and / or polypropylene glycol monomethacrylate (i) as constituent components of the copolymer (a), (b), (c), (D), (e), (f), (g), (h) and an aqueous solution polymerization of an unsaturated monomer mixture comprising 0.2 to 8 parts by weight with respect to 100 parts by weight of the total. The present invention provides a microcapsule that is a water-soluble copolymer obtained in the above manner.

  According to a fourth aspect of the present invention, there is provided the microcapsule according to the first microcapsule production method, wherein the anionic polymer electrolyte is 1 to 30 parts by weight with respect to 100 parts by weight of the oily core substance. It is.

  In the microcapsule of the present invention, the anionic polymer electrolyte to be used has a good emulsifying and dispersing property of the oily core substance, the emulsion is stable, becomes a slurry with a high concentration and low viscosity, and a cured film of an initial condensate of melamine and formaldehyde. The obtained microcapsules have an appropriate particle size, a uniform distribution, and excellent strength, denseness, water resistance, heat resistance, and temperature and humidity resistance. Moreover, since a stable capsule slurry can be obtained with a small amount of an anionic polymer electrolyte used, the microcapsules are excellent in economic efficiency.

  The present invention will be described in detail below. In the present invention, the emulsifying dispersant of the first stage is first prepared in the production method of microcapsules in which an oily core substance is emulsified and dispersed in an acidic aqueous solution and then a capsule membrane wall is formed by a curing reaction of an initial condensate of melamine and formaldehyde. Anionic polyelectrolyte used as (1) carboxyl group-containing polymerizable unsaturated monomer (a) and (2) (meth) acrylonitrile (b) and / or methyl methacrylate (c) and / or amide group Polymerizable unsaturated monomer (d) and / or hydroxyl group-containing polymerizable unsaturated monomer (e) and (3) methacryloyl polyoxyethylene acid phosphate (f) and / or methacryloyl polyoxypropylene acid phosphate (g) And (4) from polyethylene glycol monomethacrylate (h) and / or polypropylene glycol monomethacrylate (i) That an unsaturated monomer mixture of a water-soluble copolymer obtained by aqueous solution polymerization.

  The carboxyl group-containing polymerizable unsaturated monomer (a) is not particularly limited as long as it is a monomer having a carboxyl group (including an acid anhydride group) and a polymerizable unsaturated group. Acrylic acid, methacrylic acid, crotonic acid, isocrotonic acid, ethacrylic acid, propylacrylic acid, isopropylacrylic acid, itaconic acid, maleic anhydride, fumaric acid and the like. Among the above carboxyl group-containing unsaturated monomers, acrylic acid and methacrylic acid are particularly preferable.

  The carboxyl group-containing polymerizable unsaturated monomer may be a free acid or a part of the carboxyl group may form a salt such as sodium, potassium, ammonium or amine.

    The amount of the carboxyl group-containing unsaturated monomer used is 60 to 95 parts by weight, preferably 65 to 90 parts by weight, more preferably 70 to 90 parts by weight, based on 100 parts by weight of the total constituent components of the copolymer. And 75 to 85 parts by weight are particularly preferred.

    If the use amount of the carboxyl group-containing unsaturated monomer is less than 60 parts by weight based on 100 parts by weight of the total of the constituent components of the copolymer, the water solubility is insufficient, so that the oil core is used as a resin composition for producing microcapsules. Lack of emulsifying and dispersing power of the substance and lack of stability of emulsified particles. On the other hand, when the amount is more than 95 parts by weight, the water solubility is too large and the hydrophobic part is small, so that the HLB balance as an emulsifying dispersant is lacking. Therefore, the emulsified slurry of the capsule becomes abnormally high in viscosity or becomes unstable due to separation.

  (Meth) acrylonitrile (b) and / or methyl methacrylate (c) and / or amide group-containing polymerizable unsaturated monomer (d) and / or hydroxyl group-containing polymerizable unsaturated monomer (e) 2 to 20 parts by weight are used for 100 parts by weight of the total of the constituent components. (Meth) acrylonitrile is quite hydrophilic as a monomer, but becomes superhydrophobic after becoming a polymer. Therefore, the emulsifying dispersant functions to lower HLB as a hydrophobic component. On the other hand, the property as a polymer shows crystallinity, and functions as a membrane wall component of a microcapsule to improve toughness and heat resistance. Methyl methacrylate is highly hydrophilic both as a monomer and as a polymer. The amide group-containing polymerizable unsaturated monomer is water-soluble, plays a role of complementing the carboxyl group-containing unsaturated monomer as an emulsifying dispersant, and has an excellent ability as a protective colloid. The hydroxyl group-containing polymerizable unsaturated monomer has a strong hydrophilicity and serves to enhance HLB as an emulsifying dispersant and sometimes improve emulsifying dispersibility. Moreover, the hydroxyl component is rich in curability with melamine resin, and helps to form a strong membrane wall in the microcapsule.

  Examples of the amide group-containing polymerizable unsaturated monomer (d) include acrylamide, methacrylamide, α-ethylacrylamide, N, N-dimethylacrylamide, N, N-dimethylmethacrylamide, N-methylacrylamide, and N-methyl. Examples thereof include at least one monomer selected from the group consisting of methacrylamide, diacetone acrylamide, N-methylol acrylamide, N-methylol methacrylamide, methylene bisacrylamide, methylene bis methacrylamide and N-vinyl pyrrolidone.

Examples of the hydroxyl group-containing polymerizable unsaturated monomer (e) include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate, Examples include ε-caprolactone-modified acrylic monomers. These hydroxy group-containing polymerizable unsaturated monomers can be used alone or in combination of two or more. As the ε-caprolactone-modified acrylic monomer, the product name “PLAXEL FA-1” manufactured by Daicel Chemical Industries, Ltd.
”,“ Plaxel FA-2 ”,“ Plaxel FA-3 ”,“ Plaxel FA-4 ”,“ Plaxel FA-5 ”,“ Plaxel FM-1 ”,“ Plaxel FM-2 ”,“ Plaxel FM-3 ” , “Plaxel FM-4”, “Plaxel FM-5” and the like.

    Less than 2 parts by weight of (meth) acrylonitrile (b) and / or methyl methacrylate (c) and / or amide # group-containing polymerizable unsaturated monomer (d) and / or hydroxyl group-containing polymerizable unsaturated monomer (e) Then, as an emulsifying dispersant, the emulsifying and dispersing power is lacking, the stability of the emulsifying particles is lacking, and at the same time, the strength and heat resistance as a microcapsule are insufficient. When the amount is more than 20 parts by weight, the balance as an emulsifying dispersant is insufficient, and a stable slurry cannot be obtained.

  Examples of the methacryloyl polyoxyethylene acid phosphate (f) in the anionic polymer electrolyte of the present invention include the following formula (1), and examples of the methacryloyl polyoxypropylene acid phosphate (g) include the following formula (2). Is done. Either (1) or (2) may be used, or may be used in combination.

メタクリロイルポリオキシエチレンアシッドフォスフェート(ｆ)及び又はメタクリロイルポリオキシプロピレンアシッドフォスフェート(ｇ)の使用量は、水溶性共重合体の構成成分の総和１００重量部に対して０．５〜１２重量部、１〜１０重量部がより好ましい。

The amount of methacryloyl polyoxyethylene acid phosphate (f) and / or methacryloyl polyoxypropylene acid phosphate (g) used is 0.5 to 12 parts by weight based on 100 parts by weight of the total constituent components of the water-soluble copolymer. 1 to 10 parts by weight is more preferable.

  When the amount of methacryloyl polyoxyethylene acid phosphate (f) and / or methacryloyl polyoxypropylene acid phosphate (g) is less than 0.5 parts by weight, the emulsifying dispersion force is insufficient and the stability of the emulsified dispersed particles is insufficient. In addition, the microcapsule particles have a small particle size, non-uniformity, and a smaller particle size. Furthermore, the curing rate of melamine resin is slow, the strength of the capsule membrane wall is insufficient, and the heat resistance and heat and humidity resistance of the microcapsules coated on the paper substrate is insufficient, so the storage stability of the coated capsules decreases. , Resulting in a decline in commercial value. When the amount is more than 12 parts by weight, the emulsification and dispersion becomes worse, and in an extreme case, aggregation and separation occur. Melting of the melamine resin is also localized, resulting in nonuniform and weak film wall strength, resulting in unstable microcapsules.

  The polyethylene glycol monomethacrylate (h) in the anionic polymer electrolyte of the present invention is represented, for example, by the following formula (3), and the polypropylene glycol monomethacrylate (i), for example, by the following formula (4). Either (3) or (4) may be used, or may be used in combination.

ポリエチレングリコールモノメタクリレート(ｈ)及び又はポリプロピレングリコールモノメタクリレート(ｉ)が乳化分散樹脂中に共重合されると、ノニオン性の乳化剤成分としての機能を発揮する。すなわち、一般にアニオン性乳化剤を使用すると分散粒子の粒子径が小さくなりすぎる。しかし、ノニオン性の乳化剤は系のHLBを適度に調節し、乳化ミセルのサイズを大きくしてより大きな粒子径の粒子をより均一に整える作用をすることが知られている。それと同様にポリエチレングリコールモノメタクリレート(ｈ)及び又はポリプロピレングリコールモノメタクリレート(ｉ)成分が共重合された乳化分散剤は、マイクロカプセルの粒子径をより大きく、より均一に調整する作用を及ぼす。更に油性芯物質に対して少ない乳化分散樹脂の使用比率で安定なマイクロカプセルスラリーが得られるという作用ももたらす。

When polyethylene glycol monomethacrylate (h) and / or polypropylene glycol monomethacrylate (i) are copolymerized in the emulsified dispersion resin, it functions as a nonionic emulsifier component. That is, in general, when an anionic emulsifier is used, the particle size of the dispersed particles becomes too small. However, nonionic emulsifiers are known to moderately adjust the HLB of the system and increase the size of the emulsified micelles, thereby making the particles of larger particle sizes more uniform. Similarly, the emulsifying dispersant obtained by copolymerizing the polyethylene glycol monomethacrylate (h) and / or the polypropylene glycol monomethacrylate (i) component has an effect of adjusting the particle size of the microcapsules larger and more uniformly. In addition, a stable microcapsule slurry can be obtained with a small ratio of the emulsifying dispersion resin to the oily core substance.

  The amount of polyethylene glycol monomethacrylate (h) and / or polypropylene glycol monomethacrylate (i) used is 0.2 to 8 parts by weight, 0.5 to 6 parts per 100 parts by weight of the total of the components of the water-soluble copolymer. Part by weight is more preferred.

  If the polyethylene glycol monomethacrylate (h) and / or polypropylene glycol monomethacrylate (i) is less than 0.2 parts by weight, the particle size of the microcapsules is large and lacks the ability to adjust uniformly. The dispersion force decreases, the particle size becomes too large, and on the contrary, it becomes unstable.

  In this way, the anionic polymer electrolyte is prepared by polymerizing the unsaturated monomer mixture of (a) to (i) above in an aqueous solution.

  In aqueous solution polymerization, the monomer components (a), (b), (c), (d), (e), (f), (g), (h) and (i) are radically polymerized in an aqueous liquid. It is carried out by heating with stirring in the presence of an initiator. The reaction temperature is preferably about 30 to 100 ° C., and the reaction time is preferably about 0.5 to 10 hours. The reaction temperature may be adjusted by adding the monomer mixture to the reaction vessel charged with water or dropping it for a while.

  As the radical polymerization initiator, known initiators usually used in emulsion polymerization or aqueous solution polymerization of acrylic resins can be used. Specifically, as a water-soluble free radical polymerization initiator, for example, potassium persulfate, sodium persulfate, ammonium persulfate, hydrogen peroxide and the like, and these oxidizing agents, sodium bisulfite, sodium thiosulfate, Rongalite, A so-called redox initiator combined with a reducing agent such as ascorbic acid is used in the form of an aqueous solution. Further, sometimes cumene peroxide, cyclohexane peroxide, di # -t-butyl peroxide, t-butyl hydroperoxide, methyl ethyl ketone peroxide, azobisisobutyl nitrile and the like which are oil-soluble peroxides are also used.

  The anionic polymer electrolyte of the present invention can be mixed and dissolved with water at various ratios. In the production of microcapsules, the anionic polymer electrolyte can be used in an amount of 1 to 80 parts by weight with respect to 100 parts by weight of the oily core substance. It is appropriately selected depending on the particle diameter. If the amount used is too small, aggregation or separation will occur during the encapsulation process, and if the amount used is too large, the resulting capsule slurry will become highly viscous or separated, making it difficult to obtain good microcapsules. . Therefore, the amount used is preferably 1 to 30 parts by weight, and more preferably 3 to 25 parts by weight.

  The weight average molecular weight of the anionic polymer electrolyte is not particularly limited, but is generally about 1,000 to 200,000, preferably about 5,000 to 100,000. A weight average molecular weight can be adjusted with the usage-amount of a polymerization initiator. Further, the solid content concentration in the aqueous solution of the resin may be any of 10 to 40% by weight, but if it is less than 10% by weight, the concentration of the produced capsule is low and the production efficiency is poor. Becomes too high, and the dispersion of the capsule is poor, which is not preferable.

  As an initial condensate of melamine and formaldehyde as a curing agent for making the membrane wall of the microcapsule of the present invention, a mixture of melamine, paraform and formaldehyde or methylol melamine is used as a starting material. Methylolmelamine is weakly alkaline and can be easily obtained by heating a mixture of melamine and formaldehyde with stirring. Commercially available methylol melamine may be used as a starting material.

  The molar ratio of melamine to formaldehyde has a great influence on the density, membrane wall strength, heat resistance, particle size, etc. of the capsules produced, but the molar ratio of formaldehyde to melamine is about 1 to 5, preferably 1.5. -4, more preferably 2-3.5.

  Adjustment of the melamine-formaldehyde initial condensate is carried out by heating and stirring melamine and formaldehyde and / or paraformyl in the range of pH 8 to 10 to carry out a methylolation reaction. In order to improve the stability of the obtained prepolymer, particularly low temperature stability, the pH is lowered to the acidic side in some cases, and an equal weight or more of methanol is added thereto to carry out a methyl etherification reaction. After neutralization with alkali, excess methanol is removed by concentration under reduced pressure to obtain the desired stable melamine-formaldehyde precondensate.

  In the present invention, among oily core materials to be encapsulated, examples of oil include fish oil, animal oil such as lard oil, soybean oil, sesame seed oil, peanut oil, flaxseed oil, castor oil, corn oil and other vegetable oils, petroleum, There are mineral oils such as kerosene, gasoline, naphtha, paraffin, toluene and xylene. Examples of synthetic oils include biphenyl compounds, terphenyl compounds, phosphate compounds, alkylnaphthalene-based high boiling solvents, alkyl-substituted diphenylalkanes, diphenylethane, dibutyl phthalate, dioctyl phthalate, methyl salicylate, and other natural mineral oils. is there. Oily core materials include perfumes, dyes, pharmaceuticals, agricultural chemicals, foods, adhesives, catalysts, temperature indicators, developers, rust inhibitors, detergents, liquid crystals, etc., depending on the use and purpose of the microcapsule. It can be prepared by appropriately dissolving.

The outline of the microcapsule production process of the present invention is as follows.
1) An anionic polymer electrolyte having the above composition is synthesized by aqueous solution polymerization.
2) A melamine-formaldehyde initial condensate is synthesized as described above.
3) The oily core substance is emulsified and dispersed in the anionic polymer electrolyte. The emulsification dispersion is carried out in a short time of about 10 minutes by forced high-speed stirring at 5,000 to 10,000 rpm with a homogenizer or the like while maintaining the pH in the acidic range of 2 to 7.
4) Mix the melamine-formaldehyde initial condensate of 2) into the emulsified dispersion of 3), or mix the emulsified dispersion of 3) into the melamine-formaldehyde initial condensate of 2). Raise the temperature. Continue stirring at the same temperature for 0.5-5 hours. 5) Cool, adjust pH and filter.

  For pH adjustment, for example, basic substances such as caustic soda or sodium carbonate aqueous solution, amines, ammonia water, etc., for acidification, for example, formic acid, acetic acid, hydrochloric acid, sulfuric acid, citric acid, phosphoric acid, lactic acid, etc. Is used.

    The amount of the anionic polymer electrolyte in the capsule production system is 0.2 to 10, preferably 0.3 to 5, by weight with respect to the melamine-formaldehyde initial condensate. If the amount used is small, separation, thickening or aggregation occurs during encapsulation. When the amount used is large, the dispersed particles become small, which is not preferable.

    The anionic polymer electrolyte is used in an amount of 1 to 30 parts by weight with respect to 100 parts by weight of the oily core substance, and is generally determined by the encapsulation concentration, particle diameter, and viscosity. When the amount used is small, it is difficult to obtain good microcapsules because the emulsifying dispersion force is insufficient at the time of encapsulation and the slurry aggregates, which is not preferable. On the other hand, if the amount is too large, the viscosity of the slurry is excessively increased and the particle size becomes too small.

    The size of the microcapsules can be appropriately selected depending on the application. When used for pressure sensitive recording paper, the size is preferably 3 to 10 microns, more preferably 4 to 7 microns.

  The present invention is extremely useful for the production of microcapsules, particularly for microcapsules for pressure-sensitive recording paper. That is, according to the method of the present invention, the emulsifying dispersibility of the oily core substance is good, the emulsion is stable without foaming, and the slurry becomes a high-concentration, low-viscosity slurry. In addition, the distribution is uniform, the strength, the denseness, the water resistance, the heat resistance, and the temperature and humidity resistance are excellent, and the microcapsules can be easily obtained in a short manufacturing process.

  The microcapsule dispersion produced according to the present invention can be used by being applied onto a support such as paper by a curtain roll, a blade coater, an air knife coater, a clavia coater or the like.

    EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In the examples and comparative examples, parts and% are based on weight unless otherwise specified. In the examples, as a typical application example of the microcapsule, the carbonless paper that is frequently used will be described as a representative example. However, the present invention is not limited to this and can be used for other purposes as well.

  The average particle size and distribution, viscosity, encapsulation rate, color developability, stain resistance, and temperature and humidity resistance test of the microcapsule slurry were conducted in the following manner.

(Average particle size and distribution)
The average particle size of the microcapsules was measured using Shimadzu SALD-2000J (manufactured by Shimadzu Corporation). As for the particle size distribution, the ratio of the number of particles having a small particle size of 1.5 μm or less and a large particle size of microcapsule particles of 8 μm or more, which is not necessary or particularly bad for carbonless paper, to the total number of particles. It was measured.

(viscosity)
The viscosity of the microcapsule slurry at 23 ° C. was measured with a B-type viscometer at 60 rpm.

(Encapsulation rate)
The microcapsule slurry is applied to a commercially available lower carbon paper with a 0.05 mm applicator, dried at room temperature, and then measured by the degree of stain on the lower paper.

(Color development)
A slurry prepared by adding a solution of 60 parts water of 7 parts wheat starch to 33 parts microcapsule slurry was applied to a base paper with a basis weight of 40 g / m ^{2 with} a # 10 coating bar and dried at 110 ° C. for 3 minutes. Made paper on carbonless paper. This upper paper was superposed on a commercially available lower paper and printed with a typewriter to evaluate the color developability.

(Stain resistance)
An upper paper was prepared by the same method as that for the color development test, superimposed on a commercially available lower paper, and a static pressure of about 1.5 kg / cm ² was applied to evaluate the color stain on the lower paper developer.

(Heat and humidity resistance)
Apply the microcapsule slurry onto a commercially available lower carbon paper with a 0.05 mm applicator and dry it at room temperature. Place the coated paper in a constant temperature and humidity chamber at 50 ° C and 80% relative humidity. After being left for a month, the degree of surface contamination was evaluated.

[Example 1]
(Synthesis of anionic polymer electrolyte)
A reaction vessel equipped with a stirrer, a dropping funnel, a reflux condenser and a thermometer was charged with 730 parts of ion-exchanged water and heated to 60 ° C. while stirring. On the other hand, 310 parts of acrylic acid (AA, 80% solution), 13 parts of methacrylic acid (MAA), 25 parts of acrylonitrile (AN), 8 parts of methyl methacrylate (MMA), 20 parts of methacryloyl polyoxyethylene (6 mol) acid phosphate A homogeneous aqueous solution of unsaturated monomer consisting of 300 parts of ion-exchanged water is prepared in 5 parts of polyethylene glycol monomethacrylate (Nippon Yushi Co., Ltd., Blemmer PE-200) and placed in a dropping funnel, of which 10% is reacted. Added to the container. Next, the internal temperature of the reaction vessel was raised to 75 ° C., 3 parts of potassium persulfate and 10 parts of ion-exchanged water were added, and the reaction was carried out at an internal temperature of 80 ° C. for 10 minutes. Next, the remaining 90% of the unsaturated monomer aqueous solution was added dropwise at a reaction vessel internal temperature of 83 to 85 ° C. over 3 hours. On the other hand, 2 parts of potassium persulfate was dissolved in 60 parts of ion-exchanged water, placed in another dropping funnel, and added dropwise over 2 hours and 30 minutes from 1 hour after the start of dropping of the unsaturated monomer aqueous solution. Aging reaction was performed at 83 to 85 ° C. for 1 hour after the completion of the dropwise addition of the aqueous potassium persulfate solution. Thereafter, the reaction vessel was cooled to 40 ° C. or lower, and an aqueous solution in which 15 parts of caustic soda was dissolved in 90 parts of ion-exchanged water was added.

  The obtained aqueous solution of the anionic polymer electrolyte resin had a non-volatile content of 22.1%, a viscosity of 280 mPa · s (23 ° C., B-type viscometer), and a pH of 3.6.

(Synthesis of melamine formaldehyde initial condensate)
A reaction vessel equipped with a stirrer, a reflux condenser and a thermometer is charged with 240 parts of 37% formaldehyde, 180 parts of melamine, and 60 parts of 92% paraform, stirred and heated to 80 ° C. After stirring at 80 ° C. for 30 minutes to carry out the addition reaction, 720 parts of methanol and 7 parts of 10% hydrochloric acid are added, and methanol modification reaction is carried out at 60 ° C. for about 1 hour. The reaction is carried out by stirring until the reaction mixture sampled with a pipette is added to a large amount of water (for example, bucket) and the reaction becomes the end point of the reaction. Thereafter, 3 parts of a 20% sodium hydroxide aqueous solution is added.

  After cooling, methanol and water are removed by concentrating under reduced pressure until the non-volatile content of the reaction product becomes 75% to obtain a product.

  The obtained melamine formaldehyde initial condensate aqueous solution had a non-volatile content of 75.2%, a viscosity of 1,700 mPa · s (23 ° C., B-type viscometer), and a pH of 8.9.

(Production of microcapsules)
In advance, 13 parts of crystal violet lactone (CVL) were added to alkyldiphenylethane (trade name Hysol SAS-296, manufactured by Nippon Petrochemical Co., Ltd.).
In addition to 260 parts, the mixture was heated and dissolved at 90 ° C. for 10 minutes with stirring, and then cooled to prepare an oily core material. On the other hand, 130 parts of an anionic polymer electrolyte resin aqueous solution synthesized by the above method, 220 parts of water, 15 parts of a 10% aqueous solution of caustic soda and the above-prepared oily core substance are put in another container, mixed, and homogenizer (specialized machine). And emulsified for 3 minutes at 9,000 rpm. The average particle size of the obtained O / W emulsion was 5.1 μm. Next, 70 parts of the melamine formaldehyde initial condensate aqueous solution synthesized above was dissolved in 200 parts of ion-exchanged water and then added thereto. The temperature was raised to 80 ° C. and stirring was continued at 80 ° C. for 2 hours. After cooling to 40 ° C. or less, 80 parts of a 10% sodium hydroxide aqueous solution was added, stirred and mixed, and then filtered through a 120 mesh net.

  The obtained microcapsule slurry had an average particle size of 5.1 μm and a viscosity of 90 mPa · s (23 ° C., B-type viscometer). In each step during the production of the microcapsules, there was no abnormal increase in viscosity or foaming, and a good microcapsule slurry was obtained.

[Example 2]
In the unsaturated monomer aqueous solution in the synthesis of the anionic polymer electrolyte of Example 1, 310 parts of acrylic acid (AA, 80% solution), 13 parts of methacrylic acid (MAA), and 300 parts of ion-exchanged water were used instead of acrylic acid. The same procedure as in Example 1 was performed except that 326 parts of acid (AA, 80% solution) and 297 parts of ion-exchanged water were used.

  The obtained aqueous solution of the anionic polymer electrolyte resin had a non-volatile content of 22.2%, a viscosity of 290 mPa · s (23 ° C., B-type viscometer), and a pH of 3.6.

  The obtained microcapsule slurry had an average particle size of 5.0 μm and a viscosity of 70 mPa · s (23 ° C., B-type viscometer). In each step during the production of the microcapsules, there was no abnormal increase in viscosity or foaming, and a good microcapsule slurry was obtained.

[Example 3]
In the unsaturated monomer aqueous solution in the synthesis of the anionic polymer electrolyte of Example 1, 25 parts of acrylonitrile (AN) and 33 parts of acrylonitrile (AN) were used instead of 25 parts of acrylonitrile (AN) and 8 parts of methyl methacrylate (MMA). The same procedure as in Example 1 was performed.
The obtained aqueous anionic polymer electrolyte resin solution had a non-volatile content of 22.1%, a viscosity of 260 mPa · s (23 ° C., B-type viscometer), and a pH of 3.6.

  The obtained microcapsule slurry had an average particle size of 5.2 μm and a viscosity of 80 mPa · s (23 ° C., B-type viscometer). In each step during the production of the microcapsules, there was no abnormal increase in viscosity or foaming, and a good microcapsule slurry was obtained.

[Example 4]
In the unsaturated monomer aqueous solution in the synthesis of the anionic polyelectrolyte of Example 1, instead of 20 parts of methacryloyl polyoxyethylene (6 mol) acid phosphate, methacryloyl polyoxypropylene (6 mol) acid phosphate 20 was used. The same procedure as in Example 1 was carried out except that the parts were used.
The obtained aqueous anionic polymer electrolyte resin solution had a non-volatile content of 22.0%, a viscosity of 280 mPa · s (23 ° C., B-type viscometer), and a pH of 3.6.

  The obtained microcapsule slurry had an average particle size of 4.9 μm and a viscosity of 90 mPa · s (23 ° C., B-type viscometer). In each step during the production of the microcapsules, there was no abnormal increase in viscosity or foaming, and a good microcapsule slurry was obtained.

[Example 5]
In the unsaturated monomer aqueous solution used in the synthesis of the anionic polymer electrolyte of Example 1, polyethylene glycol monomethacrylate (Nippon Yushi) was used instead of 5 parts of polyethylene glycol monomethacrylate (Nippon Yushi Co., Ltd., Bremer PE-200). The same procedure as in Example 1 was carried out except that 5 parts of Bremer PE-350 (manufactured by Co., Ltd.) was used.
The resulting aqueous solution of the anionic polymer electrolyte resin had a non-volatile content of 22.0%, a viscosity of 300 mPa · s (23 ° C., B-type viscometer), and a pH of 3.5.

  The obtained microcapsule slurry had an average particle size of 5.1 μm and a viscosity of 80 mPa · s (23 ° C., B-type viscometer). In each step during the production of the microcapsules, there was no abnormal increase in viscosity or foaming, and a good microcapsule slurry was obtained.

[Example 6]
In the unsaturated monomer aqueous solution in the synthesis of the anionic polymer electrolyte of Example 1, instead of 5 parts of polyethylene glycol monomethacrylate (Nippon Yushi Co., Ltd., Bremer PE-200), polypropylene glycol monomethacrylate (Nippon Yushi) The same procedure as in Example 1 was performed except that 5 parts of Bremer PP-1000 (manufactured by Co., Ltd.) were used.
The obtained aqueous anionic polymer electrolyte resin solution had a non-volatile content of 21.9%, a viscosity of 290 mPa · s (23 ° C., B-type viscometer), and a pH of 3.5.

  The obtained microcapsule slurry had an average particle size of 4.8 μm and a viscosity of 90 mPa · s (23 ° C., B-type viscometer). In each step during the production of the microcapsules, there was no abnormal increase in viscosity or foaming, and a good microcapsule slurry was obtained.

[Example 7]
In the unsaturated monomer aqueous solution in the synthesis of the anionic polymer electrolyte of Example 1, instead of 5 parts of polyethylene glycol monomethacrylate (Nippon Yushi Co., Ltd., Bremer PE-200), polypropylene glycol monomethacrylate (Nippon Yushi) The same procedure as in Example 1 was carried out except that 5 parts of Bremer PP-500 (manufactured by Co., Ltd.) were used.
The obtained aqueous solution of the anionic polymer electrolyte resin had a non-volatile content of 22.2%, a viscosity of 280 mPa · s (23 ° C., B-type viscometer), and a pH of 3.6.

  The obtained microcapsule slurry had an average particle size of 4.9 μm and a viscosity of 80 mPa · s (23 ° C., B-type viscometer). In each step during the production of the microcapsules, there was no abnormal increase in viscosity or foaming, and a good microcapsule slurry was obtained.

[Comparative Example 1]
In the unsaturated monomer aqueous solution in the synthesis of the anionic polymer electrolyte of Example 1, 310 parts of acrylic acid (AA, 80% solution), 8 parts of methyl methacrylate (MMA), and 300 parts of ion-exchanged water were used instead of acrylic part. An anionic polymer electrolyte was synthesized in exactly the same manner as in Example 1 except that 188 parts of acid (AA, 80% solution), 106 parts of methyl methacrylate (MMA) and 324 parts of ion-exchanged water were used. .
The obtained aqueous solution of the anionic polymer electrolyte resin had a non-volatile content of 22.3%, a viscosity of 220 mPa · s (23 ° C., B-type viscometer), and a pH of 4.8.
Using the obtained aqueous anionic polymer electrolyte resin solution, an encapsulation reaction was performed in the same manner as in Example 1 to prepare a microcapsule slurry. Abnormal foaming and thickening occurred during the capsule production, and the resulting microcapsule slurry had many aggregates, and part of the oil was separated on the surface. The average particle size was 4.2 μm, and the viscosity was 3, 120 mPa · s (23 ° C., B-type viscometer).

[Comparative Example 2]
In place of 8 parts of methyl methacrylate (MMA) and 20 parts of methacryloyl polyoxyethylene (6 mol) acid phosphate in the unsaturated monomer aqueous solution in the synthesis of the anionic polymer electrolyte of Example 1, methyl methacrylate (MMA) 28 The anionic polymer electrolyte was synthesized in exactly the same manner as in Example 1 except that the part was used.
The resulting aqueous solution of the anionic polymer electrolyte resin had a non-volatile content of 22.0%, a viscosity of 240 mPa · s (23 ° C., B-type viscometer), and a pH of 3.8.
Using the obtained aqueous anionic polymer electrolyte resin solution, an encapsulation reaction was performed in the same manner as in Example 1 to prepare a microcapsule slurry. Abnormal foaming and thickening occurred during the capsule production, and the resulting microcapsule slurry had many aggregates, and part of the oil was separated on the surface. The average particle size was 3.9 μm, and the viscosity was 2,840 mPa · s (23 ° C., B-type viscometer).

[Comparative Example 3]
In the unsaturated monomer aqueous solution in the synthesis of the anionic polymer electrolyte of Example 1, 25 parts of acrylonitrile (AN), 8 parts of methyl methacrylate (MMA), 20 parts of methacryloyl polyoxyethylene (6 mol) acid phosphate, polyethylene Instead of 5 parts of glycol monomethacrylate (Nippon Yushi Co., Ltd., BLEMMER PE-200), acrylonitrile (
AN) Except for using 33 parts and 25 parts of methacryloyl polyoxyethylene (4 mol) acid phosphate, an anionic polymer electrolyte was synthesized in exactly the same manner as in Example 1.
The resulting aqueous solution of the anionic polymer electrolyte resin had a non-volatile content of 22.1%, a viscosity of 270 mPa · s (23 ° C., B-type viscometer), and a pH of 3.6.
Using the obtained aqueous anionic polymer electrolyte resin solution, an encapsulation reaction was performed in the same manner as in Example 1 to prepare a microcapsule slurry. Some foaming and thickening occurred during capsule production. The average particle size was 4.3 μm, and the viscosity was 1,240 mPa · s (23 ° C., B-type viscometer).

[Comparative Example 4]
In the unsaturated monomer aqueous solution in the synthesis of the anionic polymer electrolyte of Example 1, instead of 25 parts of acrylonitrile (AN), 8 parts of methyl methacrylate (MMA), 20 parts of methacryloyl polyoxyethylene (6 mol) acid phosphate In addition, an anionic polymer electrolyte was synthesized in the same manner as in Example 1 except that 35 parts of acrylonitrile (AN) and 18 parts of methyl methacrylate (MMA) were used.
The resulting aqueous solution of the anionic polymer electrolyte resin had a non-volatile content of 22.2%, a viscosity of 260 mPa · s (23 ° C., B-type viscometer), and a pH of 3.7.
Using the obtained aqueous anionic polymer electrolyte resin solution, an encapsulation reaction was performed in the same manner as in Example 1 to prepare a microcapsule slurry. Foaming and thickening occurred during capsule manufacture. The average particle size was 5.0 μm, and the viscosity was 1,830 mPa · s (23 ° C., B-type viscometer).

[Comparative Example 5]
In the unsaturated monomer aqueous solution in the synthesis of the anionic polymer electrolyte of Example 1, instead of 25 parts of acrylonitrile (AN) and 5 parts of polyethylene glycol monomethacrylate (Nippon Yushi Co., Ltd., Blemmer PE-200), An anionic polymer electrolyte was synthesized in the same manner as in Example 1 except that 30 parts of acrylonitrile (AN) was used.
The obtained aqueous solution of the anionic polymer electrolyte resin had a non-volatile content of 22.1%, a viscosity of 280 mPa · s (23 ° C., B-type viscometer), and a pH of 3.6.

  Using the obtained aqueous anionic polymer electrolyte resin solution, an encapsulation reaction was performed in the same manner as in Example 1 to prepare a microcapsule slurry. The average particle size was 4.5 μm, and the viscosity was 380 mPa · s (23 ° C., B-type viscometer). In each step during the production of the microcapsules, although there was some foaming, there was no abnormal increase in viscosity at all, and an apparently good microcapsule slurry was obtained.

[Comparative Example 6]
In the unsaturated monomer aqueous solution in the synthesis of the anionic polymer electrolyte of Example 1, 20 parts of methacryloyl polyoxyethylene (6 mol) acid phosphate, polyethylene glycol monomethacrylate (manufactured by NOF Corporation, BLEMMER PE-200 ) Anionic polymer electrolyte was synthesized in exactly the same manner as in Example 1 except that 25 parts of methacryloyl polyoxyethylene (6 mol) acid phosphate was used instead of 5 parts.
The resulting aqueous solution of the anionic polymer electrolyte resin had a non-volatile content of 22.1%, a viscosity of 270 mPa · s (23 ° C., B-type viscometer), and a pH of 3.6.
Using the obtained aqueous anionic polymer electrolyte resin solution, an encapsulation reaction was performed in the same manner as in Example 1 to prepare a microcapsule slurry. Some foaming and thickening occurred during capsule production. The average particle size was 4.3 μm, and the viscosity was 1,240 mPa · s (23 ° C., B-type viscometer).

[Comparative Example 7]
In the unsaturated monomer aqueous solution in the synthesis of the anionic polyelectrolyte of Example 1, 25 parts of acrylonitrile (AN), 8 parts of methyl methacrylate (MMA), 20 parts of methacryloyl polyoxyethylene (6 mol) acid phosphate, polyethylene Instead of 5 parts of glycol monomethacrylate (Nippon Yushi Co., Ltd., BLEMMER PE-200), acrylonitrile (
AN) Except for using 33 parts and methacryloyl polyoxyethylene (6 mol) acid phosphate 25 parts, the same procedure as in Example 1 was performed to synthesize an anionic polymer electrolyte.
The obtained aqueous solution of the anionic polymer electrolyte resin had a non-volatile content of 22.2%, a viscosity of 280 mPa · s (23 ° C., B-type viscometer), and a pH of 3.5.
Using the obtained aqueous anionic polymer electrolyte resin solution, an encapsulation reaction was performed in the same manner as in Example 1 to prepare a microcapsule slurry. Foaming and thickening did not occur during capsule production, and apparently good microcapsules were obtained. The average particle size was 4.1 μm, and the viscosity was 140 mPa · s (23 ° C., B-type viscometer).

  The above evaluation results are summarized in Table 1.

Claims (4)

  In a microcapsule in which an oily core substance is emulsified and dispersed in an acidic aqueous solution of an anionic polymer electrolyte and then a capsule membrane wall is formed by a curing reaction of an initial condensate of melamine and formaldehyde, the anionic polymer electrolyte is (1 ) Carboxyl group-containing polymerizable unsaturated monomer (a) and (2) (meth) acrylonitrile (b) and / or methyl methacrylate (c) and / or amide # group-containing polymerizable unsaturated monomer (d) and Or a hydroxyl group-containing polymerizable unsaturated monomer (e) and (3) methacryloyl polyoxyethylene acid phosphate (f) and / or methacryloyl polyoxypropylene acid phosphate (g) and (4) polyethylene glycol monomethacrylate (h) And / or an unsaturated monomer mixture comprising polypropylene glycol monomethacrylate (i) in an aqueous solution Microcapsules, characterized in that combined with a water-soluble copolymer obtained.   In the microcapsule according to claim 1, the anionic polymer electrolyte comprises (1) a carboxyl group-containing polymerizable unsaturated monomer (a) and (2) (meth) acrylonitrile (b) and / or methyl methacrylate (c ) And / or amide # group-containing polymerizable unsaturated monomer (d) and / or hydroxyl group-containing polymerizable unsaturated monomer (e) and (3) methacryloyl polyoxyethylene acid phosphate (f) and / or methacryloyl polyoxy A composition for an anionic polymer electrolyte comprising propylene acid phosphate (g) and (4) polyethylene glycol monomethacrylate (h) and / or polypropylene glycol monomethacrylate (i).   The microcapsule according to claim 1, wherein the anionic polymer electrolyte comprises (1) a carboxyl group-containing unsaturated monomer (a) as a constituent component of the copolymer (a), (b), (c), 60 to 95 parts by weight, (2) (meth) acrylonitrile (b) and / or methacrylic with respect to 100 parts by weight of the sum of (d), (e), (f), (g), (h) and (i) Component (a), (b), a copolymer component (a), methyl (c) and / or amide # group-containing polymerizable unsaturated monomer (d) and / or hydroxyl group-containing polymerizable unsaturated monomer (e) (C), (d), (e), (f), (g), (h) and 2 to 20 parts by weight with respect to the total of 100 parts by weight of (i), (3) methacryloyl polyoxyethylene acid phosphor Fate (f) and / or methacryloyl polyoxypropylene acid phosphate (g) To 100 parts by weight of the total of the constituent components (a), (b), (c), (d), (e), (f), (g), (h) and (i) of the copolymer 0.5 to 12 parts by weight, (4) Polyethylene glycol monomethacrylate (h) and / or polypropylene glycol monomethacrylate (i) are components of the copolymer (a), (b), (c), (d), (E), (f), (g), (h) and water solution obtained by aqueous solution polymerization of an unsaturated monomer mixture comprising 0.2 to 8 parts by weight with respect to 100 parts by weight of the total. Microcapsules that are functional copolymers. The microcapsule according to claim 1, wherein the anionic polymer electrolyte is 1 to 30 parts by weight with respect to 100 parts by weight of the oily core substance.