JP2006167655A - Microcapsule - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cheap microcapsule, having many particles of suitable size, excellent in strength, compactness, water resistance, heat resistance and hotness-wetness resistance, and also possible to be produced in a short time. <P>SOLUTION: The microcapsule is obtained by forming a wall film on the surface of an oily wick matter by a curing reaction of an initial condensate of melamine and formaldehyde in an emulsion liquid where the oily wick matter is emulsified to be dispersed in an acidic aqueous solution of an anionic polymer electrolyte, wherein the anionic polymer electrolyte is a water-soluble copolymer which is obtained by aqueous polymerization of an unsaturated monomer mixture consisting of (1) a polymeric unsaturated monomer (a) without any of a carboxyl group and a phosphate group, (2) a carboxylic-group containing polymeric unsaturated monomer (b) and (3) methacryloylpolyoxyethylene acid phosphate (c), etc. and the glass transition temperature of the water-soluble copolymer is 70°C or above. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a microcapsule having a wall film made of an amino resin.

  A microcapsule has a configuration in which a core material is confined in a minute spherical capsule and can be protected without altering the core material, and is gradually released (controlled release) as needed during its application, or It is released by destroying the capsule at a time to show the original performance of the core material.

  Today, the application range of microcapsules is extremely wide, such as pressure-sensitive recording materials represented by carbonless paper, pharmaceuticals, agricultural chemical herbicides, fragrances, adhesives, foods, detergents, dyes, catalysts, enzymes, rust inhibitors, etc. There are a wide variety. In particular, carbonless paper is widely used in a wide range of industrial fields such as courier and various slips. Carbonless paper has a structure in which a microcapsule is sandwiched between two layers of upper paper and lower paper, and the microcapsule is destroyed by the pressure applied to the upper paper and is contained in the capsule. The dye that is present reacts with the developer applied to the upper paper contact surface side of the lower paper to develop a color. Therefore, as a microcapsule, the membrane wall is dense, has heat resistance, does not change over time under high temperature and high humidity, has a strength that can not be destroyed by paper friction but can be broken by writing pressure, and color development Is required to be good.

  Microcapsules can be produced by various methods. Among them, the in-situ polymerization method is widely used because it is inexpensive, does not require a special catalyst for the polymerization reaction, and can easily produce microcapsules in a short time. It's being used. 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. However, the conventional method has a problem that the emulsifying dispersibility of the oily core substance, the denseness of the membrane wall, and the like are inferior to those of other methods.

  Various studies have been made on the composition of the emulsifying dispersant used for the production of microcapsules, particularly for the above problems. For example, Japanese Patent Publication No. 54-16949 discloses a method using an ethylene / maleic anhydride copolymer as an anionic polymer electrolyte used for emulsifying and dispersing an oily core material. According to this method, the emulsifying dispersibility of the oily core substance, the strength of the capsule membrane wall, and the denseness are improved, but the viscosity of the capsule slurry is high and the solubility of the ethylene / maleic anhydride resin in water is poor. There were difficulties in workability such as precipitation.

  Japanese Patent Application Laid-Open No. 54-49984 discloses a method using a styrene / maleic anhydride copolymer as an emulsifying dispersant. This method improves the emulsifying dispersibility of the oily core substance and can provide a stable low-viscosity capsule slurry, but has the drawback of being precipitated due to poor solubility in water at low pH.

  JP-A-56-51238 discloses a method using a styrene sulfonic acid polymer such as polystyrene sulfonic acid as an emulsifying dispersant. The styrene sulfonic acid polymer is stable even at a low pH, but has high foamability when emulsified and dispersed (emulsified and dispersed slurry) and when cured melamine resin, and is inferior in workability. For example, when a microcapsule is applied to paper or the like and used, the coating film on the paper surface is repelled by foaming, and coating unevenness is likely to occur, making commercialization difficult.

  In Japanese Patent No. 2634836, the use of a terpolymer of acrylic acid, acrylonitrile, and acid phosphooxypolyethylene glycol methacrylate as an emulsifying dispersant provides the emulsifying dispersibility and denseness of the hydrophobic core material. It has been described that improved capsules can be produced and that low viscosity and ultimately high concentration capsule slurries can be formed. However, many emulsion-dispersed particles and microcapsules having a small particle size are formed, and the particle size distribution is wide, so that there are many particles that are too small or too large. For this reason, when the obtained microcapsules are used as a material for carbonless paper, capsules whose particles are too small are not destroyed, so color developability is insufficient, and capsules remaining without being destroyed are wasted and inferior in economy. There was a problem. In addition, many particles are too large, causing bleeding and contamination.

Furthermore, in the capsule manufacturing process, the terpolymer has a weak emulsifying dispersibility with respect to the hydrophobic core material, so that the emulsification and dispersion becomes difficult when the proportion of use with respect to the hydrophobic core material is small, and the oil floats on the surface. In some cases, the capsule slurry was separated. Therefore, it is necessary to increase the amount of the ternary copolymer used, which is disadvantageous in terms of economy.
Japanese Patent Publication No.54-16949 JP 54-49984 A JP-A-56-51238 Japanese Patent No. 2634836

An object of the present invention is to provide an inexpensive microcapsule that contains many particles of an appropriate size, is excellent in strength, denseness, water resistance, heat resistance, and temperature and humidity resistance, and can be manufactured in a short time. .
Another object of the present invention is to provide a microcapsule that can reduce the ratio of the anionic polymer electrolyte to the oily core substance and is excellent in economy.
Still another object of the present invention is to provide an anionic polymer as a raw material for an anionic polyelectrolyte capable of forming a capsule slurry having good emulsification and dispersibility of an oily core substance, stable emulsion and high concentration and low viscosity. An object of the present invention is to provide an electrolyte composition and a microcapsule produced using the anionic polymer electrolyte composition.

  As a result of intensive studies to achieve the above object, the present inventors have been able to favorably emulsify and disperse an oily core substance with a small amount of use by using an anionic polymer electrolyte having a specific composition. Microcapsules containing high-density particles can be obtained, and the membrane walls of the capsules are made of a specific resin, thereby improving the density, water resistance, heat resistance, and temperature and humidity resistance. We found what could be done and completed the present invention.

  That is, the present invention provides a wall film on the surface of the oily core material by a curing reaction of an initial condensate of melamine and formaldehyde in an emulsion obtained by emulsifying and dispersing an oily core material in an acidic aqueous solution of an anionic polymer electrolyte. In which the anionic polymer electrolyte comprises (1) a polymerizable unsaturated monomer (a) containing neither a carboxyl group nor a phosphate group, and (2) a carboxyl group-containing polymerization. Obtained by aqueous solution polymerization of an unsaturated monomer mixture consisting of a polymerizable unsaturated monomer (b) and (3) methacryloyl polyoxyethylene acid phosphate (c) and / or methacryloyl polyoxypropylene acid phosphate (d) The water-soluble copolymer is characterized in that the water-soluble copolymer has a glass transition temperature of 70 ° C or higher. To provide a gastric black capsule.

  (1) The polymerizable unsaturated monomer (a) containing neither a carboxyl group nor a phosphate group is a (meth) acrylic acid alkyl ester (a-1) having 1 to 18 carbon atoms of the alkyl group, or the above (Meth) acrylic acid alkyl ester (a-1) having 1 to 18 carbon atoms of alkyl group, styrene monomer (a-2), (meth) acrylonitrile (a-3), amide bond-containing polymerizable unsaturated Monomer (a-4), polyethylene glycol monomethacrylate (a-5), polypropylene glycol monomethacrylate (a-6), hydroxyl group-containing polymerizable unsaturated monomer (a-7), epoxy group-containing polymerizable unsaturated monomer (A-8) and a mixed monomer with at least one monomer selected from the group consisting of a polyfunctional vinyl group-containing polymerizable unsaturated monomer (a-9) It is preferable that the mer.

  The unsaturated monomer mixture forming the anionic polyelectrolyte is based on the total amount of the unsaturated monomer mixture: (1) a polymerizable unsaturated monomer containing neither a carboxyl group nor a phosphate ester group ( a) 2 to 25 wt%, (2) carboxyl group-containing polymerizable unsaturated monomer (b) 60 to 95 wt%, (3) methacryloyl polyoxyethylene acid phosphate (c) and / or methacryloyl poly It may contain 0.5 to 15% by weight of oxypropylene acid phosphate (d).

  The microcapsule of the present invention may be one using 1 to 30 parts by weight of an anionic polymer electrolyte with respect to 100 parts by weight of the oily core substance.

  The present invention also provides a wall film on the surface of the oily core material by a curing reaction of an initial condensate of melamine and formaldehyde in an emulsion obtained by emulsifying and dispersing an oily core material in an acidic aqueous solution of an anionic polymer electrolyte. An anionic polymer electrolyte composition for forming an anionic polymer electrolyte used in forming a microcapsule, wherein (1) an alkyl (meth) acrylate having 1 to 18 carbon atoms in the alkyl group Ester (a-1) or (meth) acrylic acid alkyl ester (a-1) having 1 to 18 carbon atoms of the alkyl group, styrene monomer (a-2), (meth) acrylonitrile (a-3) ), Amide bond-containing polymerizable unsaturated monomer (a-4), polyethylene glycol monomethacrylate (a-5), polypropylene glycol monomethacrylate (a-6), a hydroxyl group-containing polymerizable unsaturated monomer (a-7), an epoxy group-containing polymerizable unsaturated monomer (a-8), and a polyfunctional vinyl group-containing polymerizable unsaturated monomer (a- 9) a polymerizable unsaturated monomer (a) which is a monomer mixture with at least one monomer selected from the group consisting of 9), and (2) a carboxyl group-containing polymerizable monomer. It is composed of an unsaturated monomer mixture comprising a saturated monomer (b) and (3) methacryloyl polyoxyethylene acid phosphate (c) and / or methacryloyl polyoxypropylene acid phosphate (d), and has a glass transition temperature. An anionic polymer electrolyte composition capable of forming an anionic polymer electrolyte at 70 ° C. or higher is provided.

  In the present invention, the anionic polymer electrolyte used for the production of the microcapsules has good emulsifying dispersibility of the oily core substance, the emulsion is stable, and a slurry having a high concentration and low viscosity can be formed. The resulting microcapsules contain many particles of an appropriate size and are excellent in strength, denseness, water resistance, heat resistance, and temperature and humidity resistance. Moreover, since a stable capsule slurry can be obtained even when the amount of the anionic polymer electrolyte used is reduced with respect to the oily core substance, it is excellent in economic efficiency. According to such a microcapsule, the oily core substance can be stored for a long time in a state of being encapsulated, and can be easily broken by pressurization to quickly release the oily core substance. Therefore, it is particularly suitable as a carbonless paper material that is excellent in color developability and is hardly contaminated by bleeding.

In the present invention, the glass transition temperature (Tg) of the water-soluble copolymer is the monomer unsaturated monomer M _i (i = 1, 2,...) Used for the polymerization of the water-soluble copolymer. , I) and the glass transition temperature Tg _i (i = 1, 2,..., I) of each homopolymer and the weight fraction X _i (i = 1) of the monomer M _{i in} the unsaturated monomer mixture. , 2,..., I) are substituted into the formula: 1 / Tg = Σ (X _i / Tg _i ) to show theoretical values calculated with good approximation.

  The microcapsules of the present invention are formed in an emulsion obtained by emulsifying and dispersing an oily core substance in an acidic aqueous solution of an anionic polymer electrolyte.

  The anionic polymer electrolyte comprises (1) a polymerizable unsaturated monomer (a) containing neither a carboxyl group nor a phosphate ester group, and (2) a carboxyl group-containing polymerizable unsaturated monomer (b) and (3 ) A water-soluble copolymer obtained by aqueous polymerization of an unsaturated monomer mixture comprising methacryloyl polyoxyethylene acid phosphate (c) and / or methacryloyl polyoxypropylene acid phosphate (d).

  Examples of the polymerizable unsaturated monomer (a) containing neither a carboxyl group nor a phosphate ester group include (meth) acrylic acid alkyl esters (a-1) having 1 to 18 carbon atoms in the alkyl group, and styrene-based monomers. Monomer (a-2), (meth) acrylonitrile (a-3), amide bond-containing polymerizable unsaturated monomer (a-4), polyethylene glycol monoacrylate (a-5), polypropylene glycol monomethacrylate (a-6) , Hydroxyl group-containing polymerizable unsaturated monomer (c-7), epoxy group-containing polymerizable unsaturated monomer (a-8), polyfunctional vinyl group-containing polymerizable unsaturated monomer (a-9), and two or more thereof A combined mixture is mentioned.

  Examples of the (meth) acrylic acid alkyl ester (a-1) having 1 to 18 carbon atoms in the alkyl group include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, ( N-butyl (meth) acrylate, t-butyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, (meth) Examples include decyl acrylate, dodecyl (meth) acrylate, stearyl (meth) acrylate, and the like. These 1 type (s) or 2 or more types are used in combination as appropriate. Among them, (meth) acrylic acid alkyl ester having 1 to 10 carbon atoms in the alkyl group is preferable.

  Examples of the styrene monomer (a-2) include α-methylstyrene, vinyltoluene and the like in addition to styrene. These monomers can be used alone or in combination of two or more.

  The (meth) acrylic acid alkyl ester (a-1) and styrene monomer (a-2) having 1 to 18 carbon atoms in the alkyl group can impart good hardness and toughness to the membrane wall of the microcapsule. . Moreover, it has the effect of imparting hydrophobicity necessary as an emulsifying dispersant to the polymer and lowering HLB (hydrophilic lipophilic balance).

  (Meth) acrylonitrile (a-3) is hydrophilic when the monomer is used alone, but has a function of imparting high hydrophobicity to the polymer and lowering HLB after polymerization. Furthermore, it imparts crystallinity to the polymer, and acts as a membrane wall component of the microcapsule to improve toughness and heat resistance.

  Examples of the amide bond-containing polymerizable unsaturated monomer (a-4) include acrylamide, methacrylamide, α-ethylacrylamide, N, N-dimethylacrylamide, N, N-dimethylmethacrylamide, N-methylacrylamide, N- Examples include methyl methacrylamide, diacetone acrylamide, N-methylol acrylamide, N-methylol methacrylamide, methylene bis acrylamide, methylene bis methacrylamide, N-vinyl pyrrolidone and the like. These can be used alone or in combination of two or more.

  The amide bond-containing polymerizable unsaturated monomer (a-4) is water-soluble in both the monomer itself and the polymer after polymerization, and plays a role of complementing the carboxyl group-containing polymerizable unsaturated monomer (b) as an emulsifying dispersant. Excellent ability as a protective colloid.

（式中、ｎは１〜１２の整数を示す）
で表される化合物が挙げられる Examples of the polyethylene glycol monomethacrylate (a-5) include the following formula (1):

(In the formula, n represents an integer of 1 to 12)
The compound represented by

（式中、ｎは１〜１６の整数を示す）
で表される化合物が挙げられる。 As the polypropylene glycol monomethacrylate (a-6), for example, the following formula (2)

(In the formula, n represents an integer of 1 to 16)
The compound represented by these is mentioned.

  When the polyethylene glycol monomethacrylate (a-5) and the polypropylene glycol monomethacrylate (a-6) are used as a copolymerization monomer, they can exhibit a function as a nonionic emulsifier component. Nonionic emulsifiers are generally better than anionic emulsifiers in which the particle size of the dispersed particles is reduced, in that the HLB of the system is adjusted to increase the size of the emulsified micelles and uniformly form large particles. It is advantageous. Thus, the emulsifying dispersant in which polyethylene glycol monomethacrylate (a-5) and / or polypropylene glycol monomethacrylate (a-6) is copolymerized should be controlled so that relatively large particles are distributed at a high concentration. Can do. In addition, a stable microcapsule slurry can be obtained with a small ratio of the emulsifying dispersant to the oily core substance.

  The hydroxyl group-containing polymerizable unsaturated monomer (a-7) is not particularly limited as long as it is an unsaturated monomer having a hydroxyl group. For example, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl acrylate, Examples thereof include hydroxyl group-containing acrylic monomers such as hydroxypropyl methacrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate, and ε-caprolactone-modified acrylic monomer. These are used alone or in combination of two or more. As the ε-caprolactone-modified acrylic monomer, trade names “Placcel FA-1”, “Placcel FA-2”, “Placcel FA-3”, “Placcel FA-4”, “Placcel FA-” of Daicel Chemical Industries, Ltd. 5 ”,“ Plaxel FM-1 ”,“ Plaxel FM-2 ”,“ Plaxel FM-3 ”,“ Plaxel FM-4 ”,“ Plaxel FM-5 ”and the like.

  The hydroxyl group-containing polymerizable unsaturated monomer (a-7) has a function of improving emulsification and dispersibility because both the monomer and the polymer have a large HLB and high hydrophilicity. Moreover, the hydroxyl group contained in the monomer is rich in curability with the melamine resin and functions to form a tough film wall in the microcapsule.

  The epoxy group-containing polymerizable unsaturated monomer (a-8) is not particularly limited as long as it is an unsaturated monomer containing an epoxy group. For example, glycidyl acrylate, glycidyl methacrylate (GMA), glycidyl clonate, glycidyl allyl ether , Β-glycidyl methacrylate, (3,4-epoxychlorohexyl) methacrylate, 3-epoxychloro-2-hydroxypropyl methacrylate and the like, and usually glycidyl methacrylate is often used. The epoxy group-containing polymerizable unsaturated monomer (a-8) is particularly rich in crosslinkability with a carboxyl group and has a function of reinforcing a hardening by a melamine resin to form a tough film wall in the microcapsule.

  Examples of the polyfunctional vinyl group-containing polymerizable unsaturated monomer (a-9) include divinylbenzene, ethylene glycol di (meth) acrylate, hexanediol di (meth) acrylate, polyethylene glycol di (meth) acrylate, and allyl. Divinyl monomers such as (meth) acrylate, netpentylgylcol di (meth) acrylate, pentaerythritol di (meth) acrylate; trivinyl monomers such as pentaerythritol tri (meth) acrylate and trimethylolpropane tri (meth) acrylate; Examples thereof include hexavinyl monomers such as dipentaerythritol hexa (meth) acrylate. Polyfunctional vinyl group-containing polymerizable unsaturated monomer (a-9) is excellent in internal crosslinkability, hard in microcapsules, functions to form a tough, heat-resistant film wall, and complements melamine curing To work.

  Especially, as a polymerizable unsaturated monomer (a) which does not contain any of a carboxyl group and a phosphate group, the (meth) acrylic acid alkyl ester (a-1) having 1 to 18 carbon atoms is used alone, or (Meth) acrylic acid alkyl ester (a-1) having 1 to 18 carbon atoms in the alkyl group, styrene monomer (a-2), (meth) acrylonitrile (a-3), amide bond-containing polymerizable monomer Saturated monomer (a-4), polyethylene glycol monoacrylate (a-5), polypropylene glycol monomethacrylate (a-6), hydroxyl group-containing polymerizable unsaturated monomer (c-7), epoxy group-containing polymerizable unsaturated monomer ( a-8) and at least one monomer selected from the group consisting of a polyfunctional vinyl group-containing polymerizable unsaturated monomer (a-9) Monomer mixture with preferably used.

  The amount of the (meth) acrylic acid alkyl ester (a-1) is, for example, 20 to 100% by weight, preferably 30 to 80% by weight, more preferably 40 to 70% by weight, based on the total amount of the monomer (a). Degree. The amount of the styrene monomer (a-2) is, for example, about 0 to 50% by weight, preferably 20 to 40% by weight, and more preferably about 25 to 35% by weight, with respect to the total amount of the monomer (a). The amount of (meth) acrylonitrile (a-3) is usually 0 to 80% by weight (for example, 10 to 80% by weight), preferably 20 to 80% by weight (for example 20), based on the total amount of monomer (a). The amount of the amide bond-containing polymerizable unsaturated monomer (a-4) is usually 0 to 20% by weight (for example, 1 to 20% by weight) with respect to the total amount of the monomer (a). The amount is preferably about 0 to 10% by weight (for example, 1 to 10% by weight).

  The amount of polyethylene glycol monoacrylate (a-5) is usually 0.1 to 20% by weight (for example 0.2 to 20% by weight), preferably 0.2 to 10% by weight, based on the total amount of monomer (a). % (For example, 0.5 to 5% by weight). The amount of polypropylene glycol monomethacrylate (a-6) is usually 0.1 to 20% by weight (for example 0.2 to 20% by weight), preferably 0.2 to 10% by weight, based on the total amount of monomer (a). % (For example, 0.5 to 5% by weight). The amount of the hydroxyl group-containing polymerizable unsaturated monomer (a-7) is usually 0.1 to 20% by weight (eg 0.2 to 20% by weight), preferably 0.2%, based on the total amount of the monomer (a). About 10 to 10% by weight (for example, 0.5 to 5% by weight). The amount of the epoxy group-containing polymerizable unsaturated monomer (a-8) is usually 0.1 to 10% by weight (for example, 0.2 to 10% by weight), preferably 0.8%, based on the total amount of the monomer (a). It is about 2 to 5% by weight. The amount of the polyfunctional vinyl group-containing polymerizable unsaturated monomer (a-9) is usually 0 to 5% by weight (for example, 0.1 to 5% by weight), preferably 0. 0% by weight based on the total amount of the monomer (a). About 1 to 3% by weight.

  The amount of the polymerizable unsaturated monomer (a) containing neither a carboxyl group nor a phosphoric ester group is the total amount of the unsaturated monomer mixture [= monomer components (a), (b), (c) and (d ))], For example, 2 to 25% by weight, preferably 5 to 15% by weight. If it is less than 2% by weight, the emulsifying and dispersing power as an emulsifying dispersant is weak, the emulsion particles are not stable, the strength as a microcapsule is likely to be insufficient, and if the amount exceeds 25% by weight, The balance as an emulsifying dispersant is poor and it is difficult to obtain a stable slurry.

  The carboxyl group-containing polymerizable unsaturated monomer (b) 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, and examples thereof include acrylic acid and methacrylic acid. , Crotonic acid, isocrotonic acid, α-ethylacrylic acid, β-ethylacrylic acid, β-propylacrylic acid, β-isopropylacrylic acid, itaconic acid, maleic anhydride, fumaric acid, β-carboxyethyl acrylate (β-CEA These are commercially available under the trade name “Light Ester HOA-MS” (manufactured by Kyoeisha Chemical Co., Ltd.). In addition, the carboxyl group in a molecule | numerator may be liberated and some or all may form salts, such as metals, such as sodium and potassium, ammonium, and amine.

  When the carboxyl group-containing polymerizable unsaturated monomer (b) is used for copolymerization, the stability of the emulsion can be improved and the oily core substance can be uniformly dispersed.

  The amount of the carboxyl group-containing polymerizable unsaturated monomer (b) used is 60 with respect to the total amount of the unsaturated monomer mixture [= total amount of monomer components (a), (b), (c) and (d)]. It is -95 weight%, Preferably it is 65-90 weight%, More preferably, it is 70-90 weight%, It is especially preferable that it is 75-85 weight%. If it is less than 60% by weight, the water solubility is insufficient, so that the emulsifying and dispersing power of the oily core substance is weak as a resin composition for producing microcapsules, and the stability of the emulsified particles is insufficient. When it exceeds 95% by weight, the hydrophobic portion is small and the water solubility is too large, so that the HLB balance as an emulsifying dispersant is lacking. For this reason, the capsule slurry tends to become unstable, such as abnormally high viscosity or separation.

（式中、ｎは１〜１２の整数を示す）
、及び下記式（４）

（式中、ｎは１〜１６の整数を示す）
で表される化合物が挙げられる。 As methacryloyl polyoxyethylene acid phosphate (c) and methacryloyl polyoxypropylene acid phosphate (d), respectively, the following formula (3)

(In the formula, n represents an integer of 1 to 12)
And the following formula (4)

(In the formula, n represents an integer of 1 to 16)
The compound represented by these is mentioned.

  The amount of methacryloyl polyoxyethylene acid phosphate (c) and / or methacryloyl polyoxypropylene acid phosphate (d) used (total amount) is the total amount of unsaturated monomer mixture [= monomer components (a), (b) , (C) and (d) in total] is 0.5 to 15% by weight, preferably 1 to 12% by weight. If it is less than 0.5% by weight, the emulsifying and dispersing power is weak and the stability of the dispersed particles is insufficient. In addition, particles that are too small or too large are easily formed, and the proportion of particles having an appropriate size is reduced. Furthermore, since the curing rate with a curing agent such as melamine resin is slow and the strength of the capsule membrane wall tends to be insufficient, it lacks heat resistance and heat and humidity resistance, for example, the storage stability of microcapsules applied to a paper substrate etc. Low, resulting in a decline in commercial value. When the amount is more than 15 parts by weight, the emulsification and dispersion becomes worse, which may cause aggregation and separation. In addition, since the curing proceeds locally, the strength becomes non-uniform and the film wall becomes weak, so that unstable microcapsules tend to be formed.

  In the present invention, since the glass transition temperature (Tg) of the water-soluble copolymer obtained by aqueous polymerization of the monomer mixture is 70 ° C. or higher, preferably 80 ° C. or higher, when used as an emulsifying dispersant, Microcapsules having excellent film wall hardness, strength, and heat resistance can be formed. When the Tg is less than 70 ° C., the capsule membrane wall has insufficient hardness, strength, and heat resistance. For example, when applied to a nano-carbon paper, the microcapsule has poor hardness and strength and poor color development. Also, heat resistance is reduced. Although the upper limit of Tg is not specifically limited, For example, it is about 130 degreeC.

  In aqueous solution polymerization, the polymerizable unsaturated monomer mixture of the monomer components (a), (b), (c) and (d) is heated in an aqueous liquid with stirring in the presence of a radical polymerization initiator. Can be implemented. 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 mixed solution 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 of acrylic resins can be used. Specifically, as a water-soluble free radical polymerization initiator, for example, persulfates such as potassium persulfate, sodium persulfate, ammonium persulfate, hydrogen peroxide, etc., these oxidizing agents, sodium bisulfite, thio So-called redox initiators composed of a combination with a reducing agent such as sodium sulfate, Rongalite, and ascorbic acid are each used in the form of an aqueous solution. As radical polymerization initiators other than those described above, cumene peroxide, cyclohexane peroxide, di-t-butyl peroxide, t-butyl hydroperoxide, methyl ethyl ketone peroxide, azobisisobutyronitrile, and the like can also be used.

  By the polymerization reaction, an anionic polymer electrolyte made of a water-soluble copolymer can be obtained. Although the weight average molecular weight of an anionic polymer electrolyte is not specifically limited, Generally it is about 1000-200000, Preferably it is about 5000-100000. The said weight average molecular weight can be suitably prepared according to the usage-amount of a radical polymerization initiator.

  In the present invention, the anionic polymer electrolyte can be mixed and dissolved in various proportions with water, and the anionic polymer electrolyte is dissolved in water and adjusted in pH as necessary in the form of an acidic aqueous solution. Used. When the pH is adjusted, for example, an inorganic acid such as hydrochloric acid or sulfuric acid; an organic acid such as formic acid, acetic acid, citric acid, or phosphoric acid; for example, an alkali such as caustic soda can be used. Inorganic bases such as metal hydroxides and alkali metal carbonates such as sodium carbonate; basic substances such as amines and organic bases such as aqueous ammonia can be used. The acidic aqueous solution has a pH of, for example, 1 to 6, preferably about 2 to 5.

  The solid content concentration (nonvolatile content) of the acidic aqueous solution of the anionic polymer electrolyte is, for example, about 10 to 40% by weight. If it is less than 10% by weight, the concentration of the produced capsule is low and the production efficiency is poor, and if it exceeds 40% by weight, the viscosity of the acidic aqueous solution (resin aqueous solution) of the anionic polymer electrolyte becomes too high and the dispersion of the capsule tends to be poor. It is not preferable.

  The acidic aqueous solution of the anionic polymer electrolyte thus obtained has a viscosity of, for example, about 50 to 1000 mPa · s, preferably about 100 to 500 mPa · s. When the acidic aqueous solution has a viscosity of less than 50 mPa · s, the emulsification and dispersibility with respect to the oily core substance is weak, and aggregation and separation are likely to occur in the encapsulation process. Since it becomes high viscosity, it is not preferable.

  The viscosity is a value measured at 23 ° C. using a B-type viscometer (60 rpm) for an acidic aqueous solution of an anionic polymer electrolyte having a solid concentration of about 15 to 25% by weight under the condition of pH 2 to 5.

  Examples of oily core materials include, but are not limited to, animal oils such as fish oil and lard; vegetable oils such as soybean oil, sesame oil, peanut oil, linseed oil, castor oil and corn oil; petroleum, kerosene, gasoline, naphtha, paraffin, toluene Mineral oils such as xylene; oils such as biphenyl compounds, terphenyl compounds, phosphoric acid compounds, alkylnaphthalene-based high boiling solvents, alkyl-substituted diphenylalkanes, diphenylethane, dibutyl phthalate, dioctyl phthalate, and methyl salicylate Etc. can be used. In addition, as the oily core substance, depending on the use and purpose of the microcapsule, for example, the oils exemplified above, fragrances, dyes, medicines, agricultural chemicals, foods, adhesives, catalysts, temperature indicators, color developers, rust prevention A solution in which an agent, a detergent, a liquid crystal or the like is dissolved can also be used.

  Since the anionic polymer electrolyte in the present invention has the above-described configuration, it can exhibit excellent emulsifying dispersibility with respect to the oily core substance with a small amount of use. Therefore, it is not necessary to use a large amount of the anionic polymer electrolyte when emulsifying and dispersing the oil-and-fat core material, and adverse effects such as oil floating on the surface and separation of the capsule slurry can be avoided. The amount of the anionic polymer electrolyte used is preferably about 1 to 30 parts by weight, particularly preferably about 3 to 25 parts by weight with respect to 100 parts by weight of the oily core substance. When the amount of the anionic polymer electrolyte used is less than 1 part by weight, the emulsifying and dispersing power is weak, so that aggregation, separation, and floating are likely to occur in the encapsulation process. When the amount exceeds 30 parts by weight, the viscosity of the capsule slurry obtained increases. The particle size tends to be small, it becomes difficult to obtain good microcapsules, and it is uneconomical. The amount of the anionic polymer electrolyte used can be appropriately selected according to the solid content concentration (nonvolatile content) of the capsule slurry in the production process, the viscosity, the particle size of the target microcapsules, and the like.

  For emulsification and dispersion of the oily core substance, after adding the oily core substance to the acidic aqueous solution of the anionic polymer electrolyte, a conventional stirrer such as a homogenizer is used while maintaining the pH in the acidic range of, for example, 2 or more and less than 7. And forcibly stirring. Stirring is preferably performed in a short time, for example, by a method of stirring for about 10 minutes at a high speed of 5000 to 10,000 rpm using a homogenizer.

  In an emulsion obtained by emulsifying and dispersing an oily core substance in an acidic aqueous solution of the anionic polymer electrolyte, a wall film is formed on the surface of the oily core substance by a curing reaction of an initial condensate of melamine and formaldehyde. Capsules are obtained. That is, the microcapsule of the present invention is composed of a capsule membrane wall made of a melamine resin that is a cured product of the initial condensate.

  The initial condensate of melamine and formaldehyde can be obtained using, for example, a mixture of melamine, paraformaldehyde, formaldehyde, methylol melamine or the like as a starting material. The methylolmelamine can be produced by stirring and heating a mixture of melamine and formaldehyde under weak alkaline conditions, and a commercially available product can also be used.

  The ratio of melamine and formaldehyde in the initial condensate of melamine and formaldehyde is appropriately selected from about 1 to 5, preferably 1.5 to 4, more preferably about 2 to 3.5 as the former / the latter (molar ratio). Is done. The ratio greatly affects the density, membrane wall strength, heat resistance, particle diameter, etc. of the produced capsule.

  The initial condensate of melamine and formaldehyde can be prepared using a methylolation reaction by heating and stirring melamine and formaldehyde and / or paraformaldehyde under a weak alkaline condition of about pH 8-10. In order to improve the stability of the obtained initial condensate (prepolymer), in particular, low temperature stability, the pH is lowered to the acidic side following the above reaction, and methanol equal to or more than the prepolymer formed in the reaction system. It is also possible to obtain the initial stable condensate of melamine and formaldehyde by adding methyl and neutralizing with alkali and then removing the excess methanol by concentration under reduced pressure. . The pH can be adjusted using the acid or basic substance exemplified above.

  The ratio of the anionic polymer electrolyte and the initial condensate of melamine and formaldehyde in the system during the curing reaction is, for example, the former / the latter (weight ratio) of 0.2 to 10, preferably 0.3 to 5. is there. If the ratio is too small, separation, thickening or aggregation tends to occur during encapsulation, and if the ratio is too large, the dispersed particles tend to be small, which is not preferable.

  The curing reaction using the initial condensate of melamine and formaldehyde can proceed at a moderate reaction rate under weakly acidic conditions. For this reason, there is no problem such as corrosion of the equipment due to curing under strongly acidic conditions and formation of a hard and brittle film wall due to too fast curing reaction, and the curing reaction can be easily controlled, and tough melamine A capsule membrane wall made of a resin can be formed.

  The curing reaction is performed by mixing an emulsion in which an oily core substance is emulsified and dispersed in an acidic aqueous solution of an anionic polymer electrolyte, and an initial condensate of melamine and formaldehyde, and then maintaining a temperature of about 60 to 90 ° C., for example. It can be performed by stirring for about 0.5 to 5 hours. In the mixing, the initial condensate may be added to the emulsion, or the emulsion may be added to the solution in which the initial condensate is dissolved. By the above reaction, the initial condensate of melamine and formaldehyde is cured, and a film wall made of melamine resin is formed on the surface of the oily core substance dispersed in the emulsion.

  The size of the microcapsule of the present invention can be appropriately selected depending on the application. For example, when used as a material for carbonless paper (such as pressure-sensitive recording paper), the average particle diameter is, for example, about 3 to 10 μm, preferably about 4 to 7 μm, and particularly preferably about 4.4 to 7 μm.

  Since the microcapsule of the present invention has the above-described configuration, the proportion of particles that are too small or too large is small, and has a particle size distribution that contains particles of an appropriate size at a high concentration. Specifically, the ratio of the small particle group having a particle diameter of 1.5 μm or less is, for example, 15% or less, preferably 10% or less, particularly 5% or less of the entire microcapsule. On the other hand, the ratio of the large particle group having a particle diameter of 8 μm or more is, for example, 20% or less, preferably 15% or less, particularly 8% or less of the entire microcapsule. The total ratio of the small particle group and the large particle group is, for example, 40% or less, preferably 30% or less, more preferably 15% or less, particularly 9% or less of the entire microcapsule. Such microcapsules composed of particles of uniform size are advantageous in that they are excellent in quality and can be suitably used in a wide range of fields. In particular, when used as a material for carbonless paper, particles with a particle size of 1.5 μm or less remain undestructed without being destroyed by writing pressure, and particles with a particle size of 8 μm or more cause stains. However, since the microcapsules of the present invention have a small content of any particle size, it is possible to reliably destroy the capsules with writing pressure and to form a carbonless paper excellent in color developability at low cost.

  Adjustment of the particle size distribution of the microcapsules can be made by, for example, appropriately selecting the type and amount of the monomer mixture forming the anionic polymer electrolyte, the ratio of melamine and formaldehyde in the initial condensate of melamine and formaldehyde, etc. It can be carried out.

  Microcapsules are usually obtained in the form of a capsule slurry in which microcapsules are dispersed in a solvent. In this case, the viscosity of the capsule slurry is, for example, about 50 to 2000 mPa · s, preferably about 80 to 500 mPa · s. If the viscosity of the capsule slurry is less than 50 mPa · s, it tends to settle and formation of the capsule is difficult, and if it exceeds 2000 mPa · s, the dispersion of the capsule is bad, which is not preferable because many particles are too large or too small. .

  The viscosity is a value measured at 23 ° C. using a B-type viscometer (60 rpm).

  According to the present invention, since the emulsifying dispersibility of the oily core substance is good, the emulsion is stable without foaming, and a slurry having a high concentration and a low viscosity can be formed. Has a high concentration. For this reason, it is excellent in strength, denseness, water resistance, heat resistance, and temperature and humidity resistance. Furthermore, a microcapsule having a simple manufacturing process and having the above characteristics can be obtained in a short time.

  The microcapsules of the present invention have a wide range of pressure-sensitive recording materials represented by carbonless paper, pharmaceuticals, agricultural chemical sustained release agents, fragrances, adhesives, foods, detergents, dyes, catalysts, enzymes, rust inhibitors, etc. Can be used in the field.

  In particular, the microcapsules of the present invention have a dense membrane wall, heat resistance, no change over time under high temperature and high humidity, and many particles having a size that can be easily broken by writing pressure. Therefore, it is suitable as a raw material for carbonless paper. For carbonless paper, a microcapsule dispersion (capsule slurry) is coated on a support such as paper using a conventional coater such as a roll coater, curtain roll coater, blade coater, air knife coater or gravure coater. Can be manufactured. By using the microcapsules of the present invention, it is possible to produce a carbonless paper that has a strength that is not broken by the friction level of the paper but can be broken by writing pressure, and exhibits good color development.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. “Parts” indicates “parts by weight”, the viscosity indicates a value measured at 23 ° C. using a B-type viscometer, and Tg indicates a theoretical value calculated from the above formula. The evaluation results of Examples and Comparative Examples are shown in Table 1.

Preparation 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 wt% concentration solution), 13 parts of methacrylic acid (MAA), 33 parts of methyl methacrylate (MMA), 20 parts of methacryloyl polyoxyethylene (6 mol) acid phosphate, polyethylene glycol mono A polymerizable unsaturated monomer solution consisting of 5 parts of methacrylate (Nippon Yushi Co., Ltd., trade name “Blemmer PE-30”) is uniformly dissolved in 300 parts of ion-exchanged water to obtain a polymerizable unsaturated monomer aqueous solution. And the aqueous solution was placed in a dropping funnel, 10% of which was added to the reaction vessel. Next, the internal temperature (internal temperature) of the reaction vessel is increased to 75 ° C., 3 parts of potassium persulfate (radical polymerization initiator) and 10 parts of ion-exchanged water are added to the reaction vessel, and the internal temperature of the reaction solution is 80 ° C. For 10 minutes. Next, the remaining 90% of the polymerizable unsaturated monomer aqueous solution was added dropwise over 3 hours at an internal temperature of the reaction solution of 83 to 85 ° C. On the other hand, 2 parts of potassium persulfate is dissolved in 60 parts of ion-exchanged water to prepare an aqueous potassium persulfate solution. The aqueous solution is put into another dropping funnel and 1 hour after the start of dropping of the polymerizable unsaturated monomer aqueous solution. The solution was added dropwise over 2 hours and 30 minutes. After completion of the dropwise addition of the potassium persulfate aqueous solution, an aging reaction was performed at 83 to 85 ° C for 1 hour. Thereafter, the reaction vessel was cooled to 40 ° C. or less, 15 parts of caustic soda was dissolved in 90 parts of ion-exchanged water, and an acidic aqueous solution of anionic polymer electrolyte was added.

  The acidic aqueous solution of the obtained anionic polymer electrolyte had a nonvolatile content (solid content concentration) of 21.3%, a viscosity of 380 mPa · s, a pH of 3.8, and a Tg of 106 ° C.

Adjustment example 2
(Synthesis of melamine formaldehyde initial condensate)
A reaction vessel equipped with a stirrer, a reflux condenser and a thermometer was charged with 240 parts of 37% by weight formaldehyde, 180 parts melamine, and 60 parts 92% by weight paraformaldehyde and heated to 80 ° C. while stirring. After maintaining at 80 ° C. and stirring for 30 minutes to carry out an addition reaction (methylolation reaction), 720 parts of methanol and 7 parts of 10% by weight hydrochloric acid were added, and methanol modification reaction was carried out while stirring at 60 ° C. During the reaction, when the reaction product sampled with a pipette was added to a large amount of water (water in a bucket), the time when the reaction became cloudy was judged as the end point of the reaction (about 1 hour), and then 20% strength by weight aqueous caustic soda solution 3 Department was put in. After cooling, methanol and water were removed from the reaction mixture under reduced pressure, and the product was concentrated to a non-volatile content of 75% to obtain a product.

  The obtained aqueous solution of melamine-formaldehyde initial condensate had a non-volatile content of 75.2%, a viscosity of 1700 mPa · s, and a pH of 8.9.

Preparation Example 3
(Synthesis of anionic polymer electrolyte)
In Preparation Example 1, among the monomers constituting the polymerizable unsaturated monomer mixture, AA (80 wt% solution) 326 parts were used instead of AA 310 parts and MAA 13 parts, and ion-exchanged water 297 parts were used. Except for the above, an acidic aqueous solution of an anionic polymer electrolyte was obtained in the same manner as in Preparation Example 1. The acidic aqueous solution of the obtained anionic polymer electrolyte had a nonvolatile content of 21.15, a viscosity of 380 mPa · s, a pH of 3.5, and a Tg of 105 ° C.

Preparation Example 4
(Synthesis of anionic polymer electrolyte)
In Preparation Example 1, among the monomers constituting the polymerizable unsaturated monomer mixture, MMA 33 parts, instead of 5 parts of polyethylene glycol monomethacrylate, except that 30 parts of MMA and 8 parts of glycidyl methacrylate (GMA) were used, An acidic aqueous solution of an anionic polymer electrolyte was obtained in the same manner as in Preparation Example 1. The acidic aqueous solution of the obtained anionic polymer electrolyte had a nonvolatile content of 21.1%, a viscosity of 360 mPa · s, a pH of 3.7, and a Tg of 105 ° C.

Preparation Example 5
(Synthesis of anionic polymer electrolyte)
In Preparation Example 1, among the monomers constituting the polymerizable unsaturated monomer mixture, 20 parts of methacryloyl polyoxypropylene (6 mol) acid phosphate instead of 20 parts of methacryloyl polyoxyethylene (6 mol) acid phosphate An acidic aqueous solution of an anionic polymer electrolyte was obtained in the same manner as in Preparation Example 1 except that was used. The acidic aqueous solution of the obtained anionic polymer electrolyte had a nonvolatile content of 21.2%, a viscosity of 250 mPa · s, a pH of 3.6, and a Tg of 106 ° C.

Preparation Example 6
(Synthesis of anionic polymer electrolyte)
In Preparation Example 1, among the monomers constituting the polymerizable unsaturated monomer mixture, MMA 20 parts, ethyl acrylate (EA) 18 parts instead of MMA 33 parts, polyethylene glycol monomethacrylate 5 parts, An acidic aqueous solution of an anionic polymer electrolyte was obtained in the same manner as in Preparation Example 1. The acidic aqueous solution of the obtained anionic polymer electrolyte had a non-volatile content of 21.2%, a viscosity of 260 mPa · s, a pH of 3.5, and a Tg of 96 ° C.

Preparation Example 7
(Synthesis of anionic polymer electrolyte)
In Preparation Example 1, among the monomers constituting the polymerizable unsaturated monomer mixture, MMA 20 parts, butyl acrylate (BA) 18 parts instead of MMA 33 parts and polyethylene glycol monomethacrylate 5 parts, An acidic aqueous solution of an anionic polymer electrolyte was obtained in the same manner as in Preparation Example 1. The acidic aqueous solution of the obtained anionic polymer electrolyte had a nonvolatile content of 21.0%, a viscosity of 240 mPa · s, a pH of 3.6, and a Tg of 92 ° C.

Preparation Example 8
(Synthesis of anionic polymer electrolyte)
In Preparation Example 1, among the monomers constituting the polymerizable unsaturated monomer mixture, instead of 33 parts of MMA and 5 parts of polyethylene glycol monomethacrylate, 10 parts of MMA, 10 parts of 2-hydroxyethyl methacrylate (2HEMA), 18 parts of BA Except for the points used, an acidic aqueous solution of an anionic polymer electrolyte was obtained in the same manner as in Preparation Example 1. The acidic aqueous solution of the obtained anionic polymer electrolyte had a nonvolatile content of 22.2%, a viscosity of 280 mPa · s, a pH of 3.5, and a Tg of 90 ° C.

Preparation Example 9
In Preparation Example 1, among the monomers constituting the polymerizable unsaturated monomer mixture, preparation was performed except that MMA 53 parts was used instead of MMA 33 parts and methacryloyl polyoxyethylene (6 mol) acid phosphate 20 parts. An acidic aqueous solution of an anionic polymer electrolyte was obtained in the same manner as in Example 1. The acidic aqueous solution of the obtained anionic polymer electrolyte had a nonvolatile content of 21.1%, a viscosity of 360 mPa · s, a pH of 3.9, and a Tg of 106 ° C.

Preparation Example 10
(Synthesis of anionic polymer electrolyte)
In Preparation Example 1, only 66 parts of MMA was used instead of 13 parts of MAA, 33 parts of MMA and 20 parts of methacryloyl polyoxyethylene (6 mol) acid phosphate among the monomers constituting the polymerizable unsaturated monomer mixture. Except for the above, an acidic aqueous solution of an anionic polymer electrolyte was obtained in the same manner as in Preparation Example 1. The acidic aqueous solution of the obtained anionic polymer electrolyte had a nonvolatile content of 21.2%, a viscosity of 120 mPa · s, a pH of 3.3, and a Tg of 110 ° C.

Preparation Example 11
(Synthesis of anionic polymer electrolyte)
In Preparation Example 1, among the monomers constituting the polymerizable unsaturated monomer mixture, instead of MAA 13 parts, MMA 33 parts, methacryloyl polyoxyethylene (6 mol) acid phosphate 20 parts, MMA 6 parts, methacryloyl polyoxyethylene (6 mol) An acidic aqueous solution of an anionic polymer electrolyte was obtained in the same manner as in Preparation Example 1, except that 60 parts of acid phosphate was used. The acidic aqueous solution of the obtained anionic polymer electrolyte had a nonvolatile content of 21.3%, a viscosity of 220 mPa · s, a pH of 3.6, and a Tg of 105 ° C.

Preparation Example 12
(Synthesis of anionic polymer electrolyte)
In Preparation Example 1, among the monomers constituting the polymerizable unsaturated monomer mixture, AA 290 parts, 2-ethylhexyl acrylate (2EHA) 53 parts were used instead of AA 310 parts and MMA 33 parts, Preparation Example 1 was used to obtain an acidic aqueous solution of an anionic polymer electrolyte. The acidic aqueous solution of the obtained anionic polymer electrolyte had a nonvolatile content of 21.1%, a viscosity of 420 mPa · s, a pH of 3.8, and a Tg of 61 ° C.

Example 1
Add 13 parts of crystal violet lactone (CVL) to 260 parts of alkyldiphenylethane (trade name “Hysol SAS-296”, Nippon Petrochemical Co., Ltd.), heat and dissolve at 90 ° C. for 10 minutes with stirring, and cool. An oily core material was prepared. Meanwhile, Preparation Example 1
130 parts of an acidic aqueous solution of anionic polymer electrolyte, 220 parts of water, 15 parts of a 10 wt% aqueous solution of caustic soda, and the oily core substance obtained in the above were placed in a separate container, mixed, and homogenizer (Special Mechanized Industries, Ltd.) For 3 minutes at a rotational speed of 9000 rpm. The average particle size of the obtained O / W emulsion was 5.3 μm. Next, a solution prepared by dissolving 70 parts of the melamine-formaldehyde initial condensate aqueous solution obtained in Preparation Example 2 in 200 parts of ion-exchanged water was added to the emulsion, and the temperature was raised to 80 ° C. while maintaining the temperature at 80 ° C. Stirring was continued for 2 hours. Thereafter, the mixture was cooled to 40 ° C. or lower, 80 parts of a 10% by weight aqueous sodium hydroxide solution was added, stirred and mixed, and then filtered through a 120 mesh net.

  The obtained microcapsule slurry had an average particle size of 5.3 μm and a viscosity of 160 mPa · s. 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 Example 1, a microcapsule slurry was prepared in the same manner as in Example 1 except that the acidic aqueous solution of the anionic polymer electrolyte of Preparation Example 3 was used instead of the acidic aqueous solution of the anionic polymer electrolyte of Preparation Example 1. Got. The obtained microcapsule slurry had an average particle size of 5.3 μm and a viscosity of 180 mPa · s. In addition, in each process at the time of macrocapsule production, there was no abnormal increase in viscosity or foaming, and a good microcapsule slurry was obtained.

Example 3
In Example 1, a microcapsule slurry was prepared in the same manner as in Example 1 except that the acidic aqueous solution of the anionic polymer electrolyte of Preparation Example 4 was used instead of the acidic aqueous solution of the anionic polymer electrolyte of Preparation Example 1. Got. The obtained microcapsule slurry had an average particle size of 5.0 μm and a viscosity of 140 mPa · s. In addition, in each process at the time of macrocapsule production, there was no abnormal increase in viscosity or foaming, and a good microcapsule slurry was obtained.

Example 4
In Example 1, a microcapsule slurry was prepared in the same manner as in Example 1 except that the acidic aqueous solution of the anionic polymer electrolyte of Preparation Example 5 was used instead of the acidic aqueous solution of the anionic polymer electrolyte of Preparation Example 1. Got. The obtained microcapsule slurry had an average particle size of 5.1 μm and a viscosity of 130 mPa · s. In addition, in each process at the time of macrocapsule production, there was no abnormal increase in viscosity or foaming, and a good microcapsule slurry was obtained.

Example 5
In Example 1, a microcapsule slurry was prepared in the same manner as in Example 1 except that the acidic aqueous solution of the anionic polymer electrolyte of Preparation Example 6 was used instead of the acidic aqueous solution of the anionic polymer electrolyte of Preparation Example 1. Got. The obtained microcapsule slurry had an average particle size of 5.1 μm and a viscosity of 140 mPa · s. In addition, in each process at the time of macrocapsule production, there was no abnormal increase in viscosity or foaming, and a good microcapsule slurry was obtained.

Example 6
In Example 1, a microcapsule slurry was prepared in the same manner as in Example 1 except that the acidic aqueous solution of the anionic polymer electrolyte of Preparation Example 7 was used instead of the acidic aqueous solution of the anionic polymer electrolyte of Preparation Example 1. Got. The obtained microcapsule slurry had an average particle size of 5.2 μm and a viscosity of 160 mPa · s. In addition, in each process at the time of macrocapsule production, there was no abnormal increase in viscosity or foaming, and a good microcapsule slurry was obtained.

Example 7
In Example 1, a microcapsule slurry was prepared in the same manner as in Example 1 except that the acidic aqueous solution of the anionic polymer electrolyte of Preparation Example 8 was used instead of the acidic aqueous solution of the anionic polymer electrolyte of Preparation Example 1. Got. The obtained microcapsule slurry had an average particle size of 5.0 μm and a viscosity of 180 mPa · s. In addition, in each process at the time of macrocapsule production, there was no abnormal increase in viscosity or foaming, and a good microcapsule slurry was obtained.

Comparative Example 1
In Example 1, a microcapsule slurry was prepared in the same manner as in Example 1, except that the acidic aqueous solution of the anionic polymer electrolyte of Preparation Example 9 was used instead of the acidic aqueous solution of the anionic polymer electrolyte of Preparation Example 1. Got. The obtained microcapsule slurry had an average particle size of 7.4 μm and a viscosity of 2140 mPa · s. Abnormal foaming and thickening occurred during the production of the microcapsules, and the obtained macrocapsule slurry contained a large amount of agglomerates, and part of the oil was separated on the surface.

Comparative Example 2
In Example 1, the same operation as in Example 1 was performed except that the acidic aqueous solution of the anionic polymer electrolyte of Preparation Example 10 was used instead of the acidic aqueous solution of the anionic polymer electrolyte of Preparation Example 1. However, emulsification and dispersion could not be performed at the time of producing the macrocapsule, and the two layers were separated, so that the microcapsule could not be obtained.

Comparative Example 3
In Example 1, the same operation as in Example 1 was performed except that the acidic aqueous solution of the anionic polymer electrolyte of Preparation Example 11 was used instead of the acidic aqueous solution of the anionic polymer electrolyte of Preparation Example 1. However, emulsification and dispersion could not be performed at the time of producing the macrocapsule, and the two layers were separated, so that the microcapsule could not be obtained.

Comparative Example 4
In Example 1, a microcapsule slurry was prepared in the same manner as in Example 1 except that the acidic aqueous solution of the anionic polymer electrolyte of Preparation Example 12 was used instead of the acidic aqueous solution of the anionic polymer electrolyte of Preparation Example 1. Got. The obtained microcapsule slurry had an average particle size of 3.8 μm and a viscosity of 1860 mPa · s. There was no abnormal foaming during the production of the microcapsules, but thickening occurred, the encapsulation rate was poor, and many small particles were distributed in the obtained microcapsules.

(Evaluation test)
Average particle size and distribution The particle size of the microcapsules obtained in Examples and Comparative Examples was measured using Shimadzu SALD-2000J (manufactured by Shimadzu Corporation), and the average particle size was calculated. Furthermore, the particle size was divided into a small particle group having a particle diameter of 1.5 μm or less and a large particle group having a particle diameter of 8 μm or more, and the ratio of the number of particles in each group was calculated. The results are shown in Table 1.

Viscosity About the microcapsule slurry obtained in Examples and Comparative Examples, the viscosity at 23 ° C. was measured using a B-type viscometer (60 rpm).

Encapsulation rate The microcapsule slurry obtained in Examples and Comparative Examples was applied to a commercially available lower paper for carbonless paper with a 0.05 mm applicator, dried at room temperature, and then measured according to the degree of contamination of the lower paper.

Color development property About the microcapsule slurry obtained in Examples and Comparative Examples, a solution prepared by dissolving 7 parts by weight of wheat starch in 60 parts by weight of water was added to 33 parts by weight of the microcapsule slurry, and the base paper having a basis weight of 40 g / m ² was # The paper was coated with 10 coating bars and dried at 110 ° C. for 3 minutes to prepare 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 Using the microcapsule slurry obtained in the examples and comparative examples, an upper paper was prepared in the same manner as in the color development test, and was superposed on a commercially available lower paper, and a static pressure of about 1.5 kg / cm 2 was obtained. And the color stain on the lower paper developer surface was evaluated.

Heat and humidity resistance The microcapsule slurry obtained in the examples and comparative examples was applied to one side of a commercially available lower carbon paper with a 0.05 mm applicator, and the coated paper prepared by drying at room temperature was used. After being left in a constant temperature and humidity chamber at 50 ° C. and a relative humidity of 80% for 1 month, the degree of surface contamination was evaluated.

Claims (5)

It is obtained by forming a wall film on the surface of the oily core material by the curing reaction of the initial condensate of melamine and formaldehyde in an emulsion obtained by emulsifying and dispersing an oily core material in an acidic aqueous solution of an anionic polymer electrolyte. A microcapsule in which the anionic polymer electrolyte includes (1) a polymerizable unsaturated monomer (a) containing neither a carboxyl group nor a phosphate ester group, and (2) a carboxyl group-containing polymerizable unsaturated monomer. Water-soluble copolymer obtained by aqueous solution polymerization of unsaturated monomer mixture comprising (b) and (3) methacryloyl polyoxyethylene acid phosphate (c) and / or methacryloyl polyoxypropylene acid phosphate (d) A microcapsule, wherein the water-soluble copolymer has a glass transition temperature of 70 ° C. or higher. The unsaturated monomer mixture forming the anionic polyelectrolyte is (1) a polymerizable unsaturated monomer (a) containing neither a carboxyl group nor a phosphate ester group with respect to the total amount of the unsaturated monomer mixture (a 2) -25% by weight, (2) carboxyl group-containing polymerizable unsaturated monomer (b) 60-95% by weight, (3) methacryloyl polyoxyethylene acid phosphate (c) and / or methacryloyl polyoxy The microcapsule according to claim 1, comprising 0.5 to 15% by weight of propylene acid phosphate (d). The microcapsule according to claim 1, wherein 1 to 30 parts by weight of an anionic polymer electrolyte is used with respect to 100 parts by weight of the oily core substance. The (1) polymerizable unsaturated monomer (a) containing neither a carboxyl group nor a phosphate group is a (meth) acrylic acid alkyl ester (a-1) having an alkyl group having 1 to 18 carbon atoms, or the above (Meth) acrylic acid alkyl ester (a-1) having 1 to 18 carbon atoms of alkyl group, styrene monomer (a-2), (meth) acrylonitrile (a-3), amide bond-containing polymerizable unsaturated Monomer (a-4), polyethylene glycol monomethacrylate (a-5), polypropylene glycol monomethacrylate (a-6), hydroxyl group-containing polymerizable unsaturated monomer (a-7), epoxy group-containing polymerizable unsaturated monomer (A-8) and a mixed monomer with at least one monomer selected from the group consisting of a polyfunctional vinyl group-containing polymerizable unsaturated monomer (a-9) Microcapsules according to any one of claims 1 to 3 mers. A microcapsule in which an oily core substance is emulsified and dispersed in an acidic aqueous solution of an anionic polymer electrolyte to form a wall film on the surface of the oily core substance by a curing reaction of an initial condensate of melamine and formaldehyde An anionic polyelectrolyte composition for forming an anionic polyelectrolyte used for obtaining (1) an alkyl (meth) acrylic acid alkyl ester (a-1) having 1 to 18 carbon atoms in the alkyl group Or (meth) acrylic acid alkyl ester (a-1) having 1 to 18 carbon atoms of the alkyl group, styrene monomer (a-2), (meth) acrylonitrile (a-3), amide bond-containing polymerization Unsaturated monomer (a-4), polyethylene glycol monomethacrylate (a-5), polypropylene glycol monomethacrylate (a-6), hydroxy acid From the group consisting of a group-containing polymerizable unsaturated monomer (a-7), an epoxy group-containing polymerizable unsaturated monomer (a-8) and a polyfunctional vinyl group-containing polymerizable unsaturated monomer (a-9). A polymerizable unsaturated monomer (a) containing neither a carboxyl group nor a phosphate ester group which is a mixed monomer with at least one selected monomer; and (2) a carboxyl group-containing polymerizable unsaturated monomer (b ) And (3) methacryloyl polyoxyethylene acid phosphate (c) and / or an unsaturated monomer mixture consisting of methacryloyl polyoxypropylene acid phosphate (d) and an anionic property having a glass transition temperature of 70 ° C. or higher. An anionic polymer electrolyte composition capable of forming a polymer electrolyte.