JP2008161859A - Multilayer microcapsule and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayer microcapsule excellent in impermeability of contents, and having high mechanical strength as well as high solvent resistance and high heat resistance; and to provide its manufacturing method. <P>SOLUTION: The multilayer microcapsule is incorporated into a shell material including a multilayer structure containing a first wall layer composed of an amino resin in which hydrophobic contents have a mercapto group and a second wall layer composed of an epoxy resin. Such the multilayer microcapsule is produced by forming the first wall layer composed of the amino resin having the mercapto group on the surface of the hydrophobic contents and then forming the second wall layer composed of the epoxy resin. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a multilayer microcapsule and a method for producing the same. More specifically, the present invention relates to a multilayer microcapsule in which a hydrophobic content is encapsulated in a shell and a method for producing the same.

  A microcapsule in which a hydrophobic content is encapsulated in a shell (hereinafter sometimes referred to as a “capsule shell”) serving as a partition wall is well known. Such microcapsules can be used for pressure-sensitive or heat-sensitive recording materials such as non-carbon paper, various sheets such as pressure measurement films, sustained-release preparations such as pharmaceuticals, agricultural chemicals, and fragrances, adhesives, foods, rust inhibitors, temperature indications. Its usefulness is recognized in various applications such as materials.

  In general, it is desired that the capsule shell can stably hold the encapsulated contents. However, since the capsule shell is very thin, the so-called bleed-out phenomenon, in which the contents penetrate into the shell, ooze out of the shell, or leak, becomes a problem. The bleed-out phenomenon causes problems such as peripheral contamination, degradation of the microcapsule powder characteristics, aggregation of the microcapsules, degradation of adhesion and adhesion to the substrate of the microcapsules, and defects.

  On the other hand, sustained-release preparations used in the fields of pharmaceuticals, agricultural chemicals, fertilizers, fragrances, etc., on the contrary, actively utilize this bleed-out phenomenon. At the stage before use, such as during storage, storage, and transportation, it is necessary to maintain the content of the contents at a certain level.

  Conventionally, as a microcapsule capable of solving the problem of such a bleed-out phenomenon, a capsule shell is obtained by a reaction of a compound such as urea, melamine, guanamine and formaldehyde with a so-called amino resin (for example, Urea resins, melamine resins, guanamine resins) or microcapsules composed of such crosslinked resins are known (see, for example, Patent Documents 1 and 2). Such an amino resin or its cross-linked resin has a very dense structure, so that the capsule shell is extremely excellent in impermeability such as a liquid substance, and the content contained therein is sufficiently stable. Thus, a microcapsule that can be held is obtained.

  However, capsule shells composed of amino resins are very fragile and have a problem that they are easily broken or damaged by a weak impact or pressure. In addition, depending on the application, the capsule shell body is required to have flexibility and adhesion, and the capsule shell body must be made very thin, so that it cannot necessarily have sufficient mechanical strength. There was a problem.

Therefore, a microcapsule composed of an amino resin containing a component derived from a specific water-soluble surfactant as a microcapsule having a shell having excellent mechanical properties and high mechanical strength. Has been proposed (see Patent Document 3). In particular, Example 4 of Patent Document 3 has a double structure consisting of an inner shell composed of an amino resin containing a component derived from a specific water-soluble surfactant and an outer shell composed of an epoxy resin. A microcapsule is disclosed.
Japanese Patent Publication No.46-30282 JP-A-5-154375 JP 2005-246320 A

  However, in the microcapsule having a double structure disclosed in Example 4 of Patent Document 3, the inner shell and the outer shell are thin wall layers, and the inner shell and the outer shell are not bonded to each other. The capsule strength was low, and it was still not satisfactory in terms of solvent resistance and heat resistance.

  Under the circumstances described above, the problem to be solved by the present invention is to provide a multilayer microcapsule having excellent solvent impermeability and high heat resistance in addition to high mechanical strength and a method for producing the same. It is to provide.

  As a result of various studies, the present inventors have made microcapsules into a first wall layer composed of an amino resin having high impermeability and a second wall layer composed of an epoxy resin excellent in chemical resistance and mechanical properties. When a mercapto group highly reactive with an epoxy resin is introduced into the amino resin constituting the first wall layer, the first wall layer and the second wall layer are firmly bonded to improve the capsule strength. The present invention has been completed by finding that the above problems can be solved and that the second wall layer can be formed of a melamine-crosslinked epoxy resin to obtain a multilayer microcapsule having higher performance.

  That is, the present invention is a multilayer microcapsule in which a hydrophobic content is encapsulated in a shell, and the shell is composed of a first wall layer composed of an amino resin having a mercapto group and an epoxy resin. A multilayer microcapsule characterized by having a multilayer structure including a second wall layer. In such a multilayer microcapsule, the second wall layer is preferably composed of a melamine-crosslinked epoxy resin.

  In the present invention, after the hydrophobic content is dispersed in an aqueous medium, formaldehyde is reacted with at least one selected from the group consisting of urea, thiourea, melamine, benzoguanamine, acetoguanamine, and cyclohexylguanamine. It is composed of an amino resin having a mercapto group on the surface of the content by performing a condensation reaction in the presence of a compound having a mercapto group and a carboxy group or a sulfo group using the initial condensate obtained The first wall layer is formed, and then the microcapsules in which the contents are encapsulated in the first wall layer are dispersed in an aqueous medium, and then the first group is added by adding a compound having an epoxy group. Provided is a method for producing a multilayer microcapsule, wherein a second wall layer made of an epoxy resin is formed on an outer surface of a wall layer.In such a production method, it is preferable that when the second wall layer is formed, a compound having an epoxy group is reacted with a crosslinking agent and / or in addition to the compound having an epoxy group, an epoxy melamine is used. Add condensate. Further, when the hydrophobic content is dispersed in the aqueous medium, preferably, the polysaccharide having a galactose unit and arabinose unit content of 10% by mass or more, more preferably soybean polysaccharide and / or gati gum. Use.

  In the multilayer microcapsule of the present invention, the first wall layer composed of an amino resin having a mercapto group and the second wall layer composed of an epoxy resin are firmly bonded to improve the capsule strength. In addition to being excellent in impermeability of objects, in addition to high mechanical strength, it has high solvent resistance and high heat resistance. In the method for producing a multilayer microcapsule according to the present invention, since the mercapto group is introduced into the amino resin constituting the first wall layer, the reaction with the epoxy resin constituting the second wall layer is promptly performed at a relatively low temperature. Since it progresses, a multilayer microcapsule can be manufactured efficiently.

≪Multilayer microcapsule≫
The multilayer microcapsule of the present invention is a microcapsule in which a hydrophobic content is encapsulated in a shell, and the shell is composed of a first wall layer composed of an amino resin having a mercapto group and an epoxy resin. And having a multilayer structure including a second wall layer. Hereinafter, the multilayer microcapsule may be simply referred to as “microcapsule”.

  Hereinafter, the multilayer microcapsule of the present invention will be described in detail. However, the multilayer microcapsule of the present invention is not restricted by the following description, and other than the matters exemplified below, the scope of the present invention is not impaired. It can be implemented with appropriate changes.

<Physical properties of multilayer microcapsules>
The multilayer microcapsule of the present invention has a certain degree of flexibility, and its shape changes depending on the external pressure, so it is not particularly limited. It is preferably in the form of particles.

  Although the particle diameter of the multilayer microcapsule of the present invention is not particularly limited, it is preferably 5 to 500 μm, more preferably 10 to 300 μm, and still more preferably 10 to 200 μm. If the particle size of the multilayer microcapsule is less than 5 μm, a microcapsule that does not enclose the contents may be produced during production. On the other hand, when the particle size of the multilayer microcapsule exceeds 500 μm, physical properties normally required as a microcapsule may not be maintained. The particle diameter of the multilayer microcapsule means a volume average particle diameter measured with a laser diffraction / scattering particle size distribution measuring apparatus (for example, product name: LA-910, manufactured by Horiba, Ltd.).

  The coefficient of variation (that is, the narrow particle size distribution) of the particle size of the multilayer microcapsule of the present invention is not particularly limited, but is preferably 30% or less, more preferably 25% or less, and still more preferably 20%. It is as follows. When the variation coefficient of the particle diameter of the multilayer microcapsule exceeds 30%, there are few multilayer microcapsules having an effective particle diameter, and it may be necessary to use a large number of multilayer microcapsules.

  In addition, the particle diameter and the coefficient of variation of the multilayer microcapsule of the present invention greatly depend on the particle diameter and particle size distribution of the dispersion liquid dispersed in the aqueous medium when the multilayer microcapsule is produced. Therefore, multilayer microcapsules having a desired particle diameter and coefficient of variation thereof can be obtained by appropriately adjusting the dispersion conditions of the dispersion.

<Multi-layer microcapsule shell>
In the multilayer microcapsule of the present invention, a hydrophobic content is encapsulated in a shell having a multilayer structure including a first wall layer and a second wall layer. In general, the amino resin constituting the first wall layer is highly impervious, and the epoxy resin constituting the second wall layer is excellent in chemical resistance and mechanical properties. In addition, since the amino resin constituting the first wall layer and the epoxy resin constituting the second wall layer are firmly bonded to each other via a mercapto group, the capsule strength is improved. Therefore, the multilayer microcapsules of the present invention are less likely to seep out the contents, are not easily attacked by the solvent, and the microcapsules are not cracked by drying or increasing internal pressure. Therefore, the multilayer microcapsule of the present invention is excellent in the impermeability of the contents and has high solvent resistance and high heat resistance in addition to high mechanical strength.

  In the multilayer microcapsule of the present invention, the first wall layer is composed of an amino resin having a mercapto group. The first wall layer reacts formaldehyde with at least one selected from the group consisting of urea, thiourea, melamine, benzoguanamine, acetoguanamine and cyclohexylguanamine after the hydrophobic content is dispersed in an aqueous medium. It can form by performing a condensation reaction in presence of the compound which has a mercapto group and a carboxy group, or a sulfo group using the initial condensate obtained by making it. In addition, it can be analyzed with a Fourier transform infrared spectrophotometer (FTIR) that the amino resin which comprises a 1st wall layer has a mercapto group.

  In the multilayer microcapsule of the present invention, the second wall layer is made of an epoxy resin. The second wall layer can be formed by dispersing microcapsules encapsulating hydrophobic contents in the first wall layer in an aqueous medium and then adding a compound having an epoxy group. When the second wall layer is formed, if a compound having an epoxy group is reacted with a crosslinking agent and / or an epoxy / melamine condensate is added in addition to the compound having an epoxy group, the second wall layer is formed. The strength and impermeability of the wall layer are improved, and the multilayer microcapsule has higher performance, which is preferable.

  The multilayer microcapsule of the present invention can have at least one third and subsequent wall layers on the outer surface of the second wall layer as necessary. The third and subsequent wall layers are formed using the same material as the capsule shell of the conventionally known microcapsule by a conventionally known method such as a coacervation method, an in-situ polymerization method, or an interfacial polymerization method. be able to. As materials for forming the third and subsequent wall layers, when the third and subsequent wall layers are produced by a coacervation method, for example, a compound having an isoelectric point such as gelatin or a cationic compound such as polyethyleneimine A combination with anionic compounds such as gum arabic, sodium alginate, styrene-maleic anhydride copolymer, vinyl methyl ether-maleic anhydride copolymer, phthalate ester of starch and polyacrylic acid is preferred. In addition, when the third and subsequent wall layers are produced by an in-situ polymerization method, for example, melamine-formalin resin (melamine-formalin prepolymer), radical polymerizable monomer, and the like are preferable. Further, when the third and subsequent wall layers are produced by the interfacial polymerization method, for example, a hydrophilic monomer such as polyamine, glycol, or polyhydric phenol and a hydrophobic monomer such as polybasic acid halide or polyvalent isocyanate are used. A combination is preferred, and a wall layer composed of polyamide, epoxy resin, polyurethane, polyurea or the like is formed.

  The thickness of the shell of the multilayer microcapsule of the present invention (total thickness of all wall layers) is not particularly limited, but is preferably 0.5 to 10 μm in a wet state, more preferably 1 to 1 μm. It is 10 μm, more preferably 2 to 10 μm. If the thickness of the shell of the multilayer microcapsule is less than 0.5 μm, sufficient capsule strength may not be obtained. Conversely, if the thickness of the shell of the multilayer microcapsule exceeds 10 μm, there is no particular problem, but the mass of the content per unit mass of the multilayer microcapsule decreases, which may not be preferable.

<Contents of multilayer microcapsules>
In the multilayer microcapsule of the present invention, a hydrophobic content is encapsulated in a shell. The hydrophobic content may be appropriately selected according to the use of the multilayer microcapsule, and is not particularly limited. For example, various adhesives or pressure-sensitive adhesives, plasticizers or plasticizers, and tackifiers. , Cosmetics, magnetic materials, heat storage agents, etc. (except for dispersion liquids for electrophoretic display devices containing electrophoretic particles and a solvent). The hydrophobic content is preferably a liquid material because it needs to be sufficiently dispersed in an aqueous medium during the production of multilayer microcapsules.

<Applications of multilayer microcapsules>
The multilayer microcapsule of the present invention is suitable for various uses and products such as, for example, a microcapsule type adhesive or pressure-sensitive adhesive, a microcapsule type plasticizer, a microcapsule type cosmetic, a microcapsule type magnetic substance, and a microcapsule type heat storage agent. However, it is not limited to these. As specific examples, among these uses and products, a microcapsule type plasticizer is, for example, a plasticizer or a plasticizer used for a resin composition and an adhesive sheet material disclosed in JP-A-6-172725. And a microcapsule-type particle enclosing a tackifier. Further, the microcapsule type heat storage agent can be applied to, for example, a heat storage sheet for building members and a microcapsule type heat storage material used for a heat storage building member disclosed in Japanese Patent Application Laid-Open No. 2000-314187. it can. Similarly, other applications and products can be applied to microcapsule-type particles used in other conventionally known applications and products.

≪Method for producing multilayer microcapsules≫
In the method for producing a multilayer microcapsule according to the present invention (hereinafter sometimes referred to as “the production method of the present invention”), a hydrophobic content is dispersed in an aqueous medium, and then urea, thiourea, melamine, benzoguanamine, Using an initial condensate obtained by reacting formaldehyde with at least one selected from the group consisting of acetoguanamine and cyclohexylguanamine, a condensation reaction is carried out in the presence of a compound having a mercapto group and a carboxy group or a sulfo group. And forming a first wall layer composed of an amino resin having a mercapto group on the surface of the content, and then placing the microcapsules in which the content is encapsulated in the first wall layer in an aqueous medium. After being dispersed in, the epoxy resin is formed on the outer surface of the first wall layer by adding a compound having an epoxy group. And forming a second wall layer.

  Hereinafter, the production method of the present invention will be described in detail according to each step. However, the production method of the present invention is not restricted by the following description, and the scope of the present invention is not impaired except for the matters exemplified below. And can be implemented with appropriate changes.

<Distribution of contents>
First, the hydrophobic content is dispersed in an aqueous medium. The aqueous medium is not particularly limited. For example, water or a mixed solvent of water and a hydrophilic organic solvent can be used. When water and a hydrophilic organic solvent are used in combination, the amount of water is preferably 70 to 95% by mass, more preferably 75 to 95% by mass, and still more preferably 80 to 95% by mass.

  The hydrophilic organic solvent is not particularly limited. For example, alcohols such as methanol, ethanol, n-propyl alcohol, isopropyl alcohol, and allyl alcohol; ethylene glycol, propylene glycol, butylene glycol, hexylene glycol, Glycols such as pentanediol, hexanediol, heptanediol, dipropylene glycol; ketones such as acetone, methyl ethyl ketone, methyl propyl ketone, methyl isobutyl ketone; esters such as methyl formate, ethyl formate, methyl acetate, methyl acetoacetate; Diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, ethylene glycol monomethyl ether, Chi glycol monoethyl ether, ethers such as dipropylene glycol monomethyl ether; and the like. These hydrophilic organic solvents may be used alone or in combination of two or more.

  The aqueous medium may be used in combination with another solvent in addition to water and a hydrophilic organic solvent. Examples of the other solvent include hexane, cyclopentane, pentane, isopentane, octane, benzene, toluene, xylene, ethylbenzene, aminyl squalene, petroleum ether, terpene, castor oil, soybean oil, paraffin, and kerosene. When another solvent is used in combination, the amount used is preferably 30% by mass or less, more preferably 25% by mass or less, and still more preferably 20% by mass or less, with respect to an aqueous medium containing water and a hydrophilic organic solvent. It is.

  The amount of the content dispersed in the aqueous medium is not particularly limited, but is preferably 5 to 70 parts by mass, more preferably 8 to 65 parts by mass, and still more preferably 100 parts by mass of the aqueous medium. 10 to 60 parts by mass. If the amount of dispersion is less than 5 parts by mass, the concentration of the content is low, so it takes a long time to form the capsule shell, the target multilayer microcapsules cannot be prepared, and the multilayer microcapsules with a wide particle size distribution Thus, production efficiency may be reduced. On the other hand, when the amount of dispersion exceeds 70 parts by mass, the contents may aggregate or the aqueous medium may be suspended in the contents, making it impossible to produce multilayer microcapsules.

  When dispersing the contents in the aqueous medium, a dispersant may be used as necessary. Although it does not specifically limit as a dispersing agent, For example, water-soluble polymer (For example, polysaccharides, such as polyvinyl alcohol (PVA), carboxymethylcellulose (CMC), gelatin, gum arabic, soybean polysaccharide, gati gum) And surfactants (for example, anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants) and the like. These dispersants may be used alone or in combination of two or more. The amount of these dispersants to be added is not particularly limited as long as the formation of the first wall layer is not inhibited, and may be appropriately adjusted.

  When dispersing the hydrophobic contents in an aqueous medium, the present inventors, as a dispersant, particularly a specific polysaccharide having a polymer structure bound with a water-soluble monosaccharide such as galactose or arabinose (for example, If soy polysaccharide (gati gum) is used, the reducing sugar part (specifically, monosaccharide part having an aldehyde group or a ketone group) of such a polysaccharide is composed of urea, thiourea, benzoguanamine, acetoguanamine and cyclohexylguanamine. Since the polysaccharide has a large number of such starting points, the amino resin having a mercapto group is used as a starting point for reacting with the initial condensate obtained by reacting at least one selected from the group with formaldehyde. The first wall layer composed of the above has a dense structure, and the solvent resistance of the multilayer microcapsule is improved. It was heading. Specifically, when ordinary polysaccharides such as gum arabic are used, multilayer microcapsules are resistant to methanol, but when specific polysaccharides such as those described above are used, multilayer microcapsules are resistant to ethanol. It becomes resistant to it.

  In the present invention, the polysaccharide suitably used as a dispersant preferably has a content of galactose units and arabinose units of 10% by mass to 95% by mass, more preferably 20% by mass to 90% by mass, Preferably they are 30 mass% or more and 85 mass% or less. The content of galactose units and arabinose units in the polysaccharide is determined by hydrolyzing the polysaccharide and then, for example, high-performance liquid chromatography (HPLC) or liquid chromatography / mass spectrometry (LC / MS). Can be analyzed.

  Examples of the polysaccharide as described above include many soybeans such as trade name: Soya Five-S series (produced by Fuji Oil Co., Ltd.) and trade name: SM series (produced by Saneigen FFI Co., Ltd.). Saccharides; trade name: Gati Gum such as Gati Gum SD (manufactured by Saneigen FFI Co., Ltd.); These polysaccharides may be used alone or in combination of two or more. Of these polysaccharides, soybean polysaccharides and / or gati gum are particularly suitable.

  The number average molecular weight of the polysaccharide used in the present invention is not particularly limited, but is preferably 1,000 or more and 1,000,000 or less, more preferably 10,000 or more and 900,000 or less, More preferably, it is 50,000 or more and 500,000 or less. When the number average molecular weight of the polysaccharide is less than 1,000, the solvent resistance of the multilayer microcapsule may be lowered. On the other hand, when the number average molecular weight of the polysaccharide exceeds 1,000,000, the viscosity of the aqueous polysaccharide solution becomes too high, and the formation of the first wall layer may be inhibited. In addition, the number average molecular weight of polysaccharide can be measured by gel permeation chromatography (GPC; for example, polystyrene conversion), for example.

  The concentration of the aqueous polysaccharide solution when the hydrophobic content is dispersed in the aqueous medium is not particularly limited. For example, it is preferably 0.1% by mass or more and 90% by mass or less, more preferably 1% by mass. % To 70% by mass, more preferably 3% to 50% by mass, and most preferably 5% to 35% by mass. If the concentration of the aqueous polysaccharide solution is less than 0.1% by mass, the effect of stably dispersing the hydrophobic contents may not be obtained. On the other hand, when the concentration of the aqueous polysaccharide solution exceeds 90% by mass, the viscosity of the aqueous polysaccharide solution becomes too high, which may inhibit the formation of the first wall layer.

<Preparation of initial condensate>
Next, at least one selected from the group consisting of urea, thiourea, benzoguanamine, acetoguanamine and cyclohexylguanamine (hereinafter sometimes referred to as “amino compound”) and formaldehyde are reacted to prepare an initial condensate.

  The initial condensate obtained by reacting an amino compound with formaldehyde is a compound that becomes a precursor of a so-called amino resin (that is, urea resin, melamine resin, guanamine resin). By using a specific initial condensate, a first wall layer composed of an amino resin can be formed. By the presence of a compound having a mercapto group and a carboxy group or a sulfo group, an amino group obtained from the initial condensate is obtained. Mercapto groups can be introduced into the resin.

  As for the initial condensate, (1) when at least one of urea and thiourea (hereinafter sometimes referred to as “urea compound”) is reacted with formaldehyde, it becomes an initial condensate that gives a urea resin, (2 ) When melamine and formaldehyde are reacted, it becomes an initial condensate that gives a melamine resin, and (3) at least one of benzoguanamine, acetoguanamine and cyclohexylguanamine (hereinafter sometimes referred to as “guanamine compound”) and formaldehyde When the is reacted, it becomes an initial condensate giving a guanamine resin. Further, (4) when at least two of urea compounds, melamine and guanamine compounds are reacted with formaldehyde, it becomes an initial condensate that gives a resin in which at least two of urea resin, melamine resin and guanamine resin are mixed. . These initial condensates (1) to (4) may be used alone or in combination of two or more.

  In the reaction between an amino compound and formaldehyde, water is generally used as a solvent. Therefore, as the reaction form, for example, a method in which an amino compound is mixed with a formaldehyde aqueous solution to react, a water solution is added to trioxane or paraformaldehyde to prepare a formaldehyde aqueous solution, and the amino compound is mixed with the obtained formaldehyde aqueous solution. The method of making it react is mentioned. From the viewpoint of economy, for example, it is not necessary to prepare an aqueous formaldehyde solution and the availability of the aqueous formaldehyde solution is preferable. When an amino compound is mixed with an aqueous formaldehyde solution, the amino compound may be added to the aqueous formaldehyde solution or the aqueous formaldehyde solution may be added to the amino compound. In addition, it is preferable to perform a condensation reaction, stirring, for example using a conventionally well-known stirring apparatus.

  As the amino compound, urea, melamine and benzoguanamine are preferable, and melamine, a combination of melamine and urea, and a combination of melamine and benzoguanamine are more preferable.

  As the amino compound, in addition to the amino compound as described above, another amino compound may be used. Examples of other amino compounds include capriguanamine, ameline, amide, ethylene urea, propylene urea, and acetylene urea. When these other amino compounds are used, these other amino compounds are handled as amino compounds that are used as raw materials for the initial condensate.

  In the reaction for obtaining the initial condensate, the addition amount of the amino compound and formaldehyde is not particularly limited, but is preferably a molar ratio of amino compound / formaldehyde, preferably 1 / 0.5 to 1/10, more preferably. Is 1/1 to 1/8, more preferably 1/1 to 1/6. If the amino compound / formaldehyde molar ratio is less than 1/10, the amount of unreacted formaldehyde increases, and the reaction efficiency may decrease. On the contrary, when the molar ratio of amino compound / formaldehyde exceeds 1 / 0.5, the amount of unreacted amino compound increases, and the reaction efficiency may decrease. When the reaction is carried out using water as a solvent, the addition amount of the amino compound and formaldehyde relative to the solvent, that is, the concentration of the amino compound and formaldehyde at the time of preparation is preferably higher as long as the reaction is not particularly hindered.

  The reaction temperature for carrying out the reaction for obtaining the initial condensate is not particularly limited, but is preferably 55 to 85 ° C, more preferably 60 to 80 ° C, and further preferably 65 to 75 ° C. The reaction may be terminated by an operation such as cooling the reaction solution to room temperature (for example, 25 to 30 ° C.). Thereby, the reaction liquid containing an initial condensate is obtained. In addition, reaction time is not specifically limited, According to the preparation amount, it can set suitably.

<Formation of the first wall layer>
Subsequently, a compound having a mercapto group (—SH) and a carboxy group (—COOH) or a sulfo group (—SO ₃ H) (hereinafter referred to as “thiol”) using an initial condensate in an aqueous medium in which the contents are dispersed. A first wall layer composed of an amino resin having a mercapto group is formed on the surface of the content by performing a condensation reaction in the presence of a compound. By this operation, the microcapsule encapsulated in the first wall layer whose content is made of an amino resin having a mercapto group is obtained.

  The addition amount of the initial condensate is not particularly limited, but is preferably 0.5 to 10 parts by mass, more preferably 0.5 to 5 parts by mass, and still more preferably, with respect to 1 part by mass of the contents. 0.5 to 3 parts by mass. By adjusting the addition amount of the initial condensate, the thickness of the first wall layer can be easily controlled. If the addition amount of the initial condensate is less than 0.5 parts by mass, a sufficient amount of the first wall layer cannot be formed, and the thickness of the first wall layer becomes small. Impermeability may be reduced. On the other hand, when the amount of the initial condensate added exceeds 10 parts by mass, the thickness of the first wall layer increases, so that flexibility and transparency may be deteriorated.

  The method for adding the initial condensate to the aqueous medium is not particularly limited, and may be batch addition or sequential addition (continuous addition and / or intermittent addition). The addition of the initial condensate is preferably performed while stirring using a conventionally known stirring device.

  The thiol compound used in the condensation reaction is not particularly limited. For example, cysteine (2-amino-3-mercaptopropionic acid), mercaptoacetic acid, mercaptopropionic acid, mercaptobenzoic acid, mercaptosuccinic acid, Examples include mercaptoethanesulfonic acid, mercaptopropanesulfonic acid, alkali metal salts thereof, alkaline earth metal salts, ammonium salts, and the like. These thiol compounds may be used alone or in combination of two or more. Of these thiol compounds, L-cysteine is preferable from the viewpoint of economy such as easy availability.

  Although the addition amount of a thiol compound is not specifically limited, Preferably it is 1-20 mass parts with respect to 100 mass parts of initial condensates, More preferably, it is 1-10 mass parts, More preferably, it is 1-5 masses. Part. When the addition amount of the thiol compound is less than 1 part by mass, there are too few mercapto groups introduced into the amino resin, so that a strong bond may not be formed with the epoxy resin constituting the second wall layer. On the contrary, when the addition amount of the thiol compound exceeds 20 parts by mass, the strength and impermeability of the first wall layer may be lowered.

  The method of adding the thiol compound to the aqueous medium is not particularly limited. For example, after adding the initial condensate to the aqueous medium in which the contents are dispersed, the thiol compound is added to the aqueous solution. It is preferable to drop in the form. In addition, it is preferable to perform a condensation reaction, stirring using a conventionally well-known stirring apparatus.

  In the production method of the present invention, a first wall layer is formed on the surface of the contents by subjecting the initial condensate to a condensation reaction in the presence of a thiol compound in an aqueous medium in which the contents are dispersed. . Specifically, while reacting the amino group of the initial condensate with the carboxy group or sulfo group of the thiol compound, the condensation reaction of the initial condensate is performed to deposit an amino resin having a mercapto group on the surface of the contents. The first wall layer.

  Although the reaction temperature at the time of performing a condensation reaction is not specifically limited, Preferably it is 10-150 degreeC, More preferably, it is 20-100 degreeC, More preferably, it is 30-80 degreeC. When the reaction temperature during the condensation reaction is less than 10 ° C., the condensation reaction is slow and the first wall layer may not be sufficiently formed. Conversely, if the reaction temperature during the condensation reaction exceeds 150 ° C., formation of the first wall layer may be inhibited. The reaction time is not particularly limited, and can be appropriately set according to the charged amount and the reaction temperature at the time of performing the condensation reaction, but is usually in the range of several minutes to several tens of hours. Generally, when the reaction temperature at the time of performing the condensation reaction is low, the reaction time is lengthened. Conversely, when the reaction temperature at the time of performing the condensation reaction is high, the reaction time may be shortened.

  An aging period may be provided after the condensation reaction. The temperature during aging is not particularly limited, but is preferably the same as or slightly higher than the reaction temperature at the time of performing the condensation reaction. The aging time is not particularly limited, but is preferably 0.5 to 5 hours, more preferably 1 to 3 hours.

  As described above, when dispersing the hydrophobic contents in an aqueous medium, the present inventors have a specific structure having a polymer structure in which water-soluble monosaccharides such as galactose and arabinose are bound as a dispersant. It has been found that the use of polysaccharides (for example, soybean polysaccharide, gati gum) improves the solvent resistance of multilayer microcapsules. However, the present inventors have not only used these specific polysaccharides, but also used ordinary polysaccharides such as gum arabic, the temperature at which the condensation reaction is performed, and It has been found that the solvent resistance of the multilayer microcapsules is further improved by appropriately adjusting the time, the temperature during the subsequent aging, and the aging time. Specifically, the multilayer microcapsules become resistant to isopropanol. In order to further improve the solvent resistance of the multi-layer microcapsules, the reaction temperature when performing the condensation reaction of the initial condensate is set higher within the above range, and / or the temperature at the aging is set higher than the reaction temperature. And / or the aging time may be set long within the above range.

  After forming the first wall layer, the obtained microcapsules may be separated from the aqueous medium by a conventionally known method such as suction filtration or natural filtration, if necessary. The amino resin that constitutes the wall layer is very brittle and may be broken or damaged even by a weak impact or pressure. Therefore, it is preferable to subject it to the next step without separation from the aqueous medium. .

<Classification and cleaning of multilayer microcapsules>
The microcapsules obtained in the step of forming the first wall layer are preferably classified in order to obtain multi-layer microcapsules having a narrow particle size distribution, and / or to improve the product quality by removing impurities. It is preferable to wash.

  The classification of the microcapsules is carried out as it is for the dispersion containing the microcapsules in the aqueous medium as it is or after dilution with an arbitrary aqueous medium, for example, a sieve type, a filter type, a centrifugal sedimentation, etc. Using a method such as an equation or a natural sedimentation method, the microcapsules may be made to have a desired particle size or particle size distribution. Note that the sieve type is effective for microcapsules having a relatively large particle size.

  Microcapsules can be washed with a dispersion containing microcapsules in an aqueous medium as it is or after being diluted with an arbitrary aqueous medium or the like, and then a conventionally known method such as centrifugal sedimentation, natural sedimentation, etc. Using this method, the microcapsules are settled, the supernatant is discarded, the sediment is recovered, and the operation of redispersing in an arbitrary aqueous medium or the like may be repeated. For microcapsules having a relatively large particle size, it is preferable to employ a natural sedimentation method in order to prevent destruction and damage of the microcapsules.

<Formation of second wall layer>
Next, after the microcapsules in which the hydrophobic content is encapsulated in the first wall layer are dispersed in an aqueous medium, a compound having an epoxy group (hereinafter sometimes referred to as “epoxy compound”) is added. A second wall layer made of an epoxy resin is formed on the outer surface of the first wall layer. By this operation, a multilayer microcapsule is obtained in which the hydrophobic content is encapsulated in a shell having a first wall layer composed of an amino resin having a mercapto group and a second wall layer composed of an epoxy resin. .

  Examples of the aqueous medium in which the microcapsules in which the hydrophobic content is encapsulated in the first wall layer are dispersed include the above-described aqueous media in which the hydrophobic content is dispersed when forming the first wall layer. Such an aqueous medium is mentioned. In addition, since the microcapsules in which the hydrophobic content is encapsulated in the first wall layer are obtained in the form of a dispersion in the aqueous medium, the microcapsules are separated from the aqueous medium and re-dispersed in the aqueous medium again. Instead, the dispersion in the aqueous medium may be subjected to the step of forming the second wall layer as it is or after concentration or dilution.

  Although it does not specifically limit as an epoxy compound, The water-soluble epoxy compound which has two or more epoxy groups in 1 molecule is preferable, for example, sorbitol polyglycidyl ether, sorbitan polyglycidyl ether, polyglycerol polyglycidyl Ether, pentaerythritol polyglycidyl ether, triglycidyl tris (2-hydroxyethyl) isocyanurate, trimethylolpropane polyglycidyl ether, neopentyl glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, diglycidyl adipate Examples include ether. These epoxy compounds may be used alone or in combination of two or more.

  The mass average molecular weight of the epoxy compound is preferably 300 to 100,000, more preferably 300 to 75,000, and still more preferably 300 to 50,000. When the mass average molecular weight of the epoxy compound is less than 300, the second wall layer having sufficient strength may not be obtained. On the other hand, when the mass average molecular weight of the epoxy compound exceeds 100,000, the viscosity of the reaction system becomes high and stirring may be difficult.

  The addition amount of the epoxy compound is not particularly limited, but is preferably 0.5 to 10 parts by mass with respect to 1 part by mass of the microcapsules in which the hydrophobic content is encapsulated in the first wall layer. Preferably it is 0.5-5 mass parts, More preferably, it is 0.5-3 mass parts. By adjusting the addition amount of the epoxy compound, the thickness of the second wall layer can be easily controlled. If the addition amount of the epoxy compound is less than 0.5 parts by mass, a sufficient amount of the second wall layer cannot be formed, and the thickness of the second wall layer is reduced, so that the strength of the second wall layer is reduced. There are things to do. On the contrary, when the addition amount of the epoxy compound exceeds 10 parts by mass, the thickness of the second wall layer is increased, so that flexibility and transparency may be deteriorated.

  The method for adding the epoxy compound to the aqueous medium is not particularly limited, and may be batch addition or sequential addition (continuous addition and / or intermittent addition). For example, it is preferable to add the epoxy compound in the form of an aqueous solution while dispersing the microcapsules whose contents are encapsulated in the first wall layer in an aqueous medium.

  When forming the 2nd wall layer comprised with an epoxy resin, a crosslinking agent can be made to react with an epoxy compound. By reacting with the cross-linking agent, the strength of the second wall layer, and hence the strength of the shell body, is improved, so that the shell body is destroyed or damaged when the multilayer microcapsules are subsequently separated or washed. Can be suppressed.

  The crosslinking agent is not particularly limited, and examples thereof include sodium diethyldithiocarbamate (including hydrate), diethylammonium diethyldithiocarbamate (including hydrate), dithiooxalic acid and dithiocarbonate. . These crosslinking agents may be used alone or in combination of two or more.

  Although the addition amount of a crosslinking agent is not specifically limited, Preferably it is 1-100 mass parts with respect to 100 mass parts of epoxy compounds, More preferably, it is 5-90 mass parts, More preferably, it is 10-80 mass parts. It is. When the addition amount of the crosslinking agent is less than 1 part by mass, the strength of the second wall layer may not be sufficiently increased. On the contrary, when the addition amount of the crosslinking agent exceeds 100 parts by mass, the crosslinking agent reacts excessively with the epoxy group of the epoxy compound, so that the flexibility of the second wall layer may be lowered.

  The addition method of the crosslinking agent to the aqueous medium may be added together with the epoxy compound or may be added before or after the addition of the epoxy compound, and is not particularly limited. After adding the epoxy compound in the form of an aqueous solution to the aqueous medium in which the microcapsules encapsulated in the layer are dispersed, it is preferable to drop the crosslinking agent in the form of an aqueous solution while stirring for a while.

  When forming the 2nd wall layer comprised with an epoxy resin, in addition to an epoxy compound, an epoxy melamine condensate can be added. By adding the epoxy / melamine condensate, the impermeability of the second wall layer and hence the impermeability of the shell body are improved, so that the microcapsules have higher performance.

  The epoxy-melamine condensate is not particularly limited as long as it is an initial condensate produced from an epoxy compound, melamine, and formaldehyde by a conventionally known method, and further, urea, thiourea, benzoguanamine, At least one selected from the group consisting of acetoguanamine and cyclohexylguanamine can be reacted. As a preferable specific example of the epoxy-melamine condensate, for example, a compound obtained by reacting an epoxy compound with urea is further reacted with an initial condensate obtained by reacting melamine, urea and formaldehyde. It is a produced condensate.

  The addition amount of the epoxy / melamine condensate is not particularly limited, but is preferably 0 to 10 parts by mass, more preferably 0 to 8 parts by mass, and still more preferably 0 to 0 parts by mass with respect to 1 part by mass of the epoxy compound. 5 parts by mass. When the addition amount of the epoxy / melamine condensate exceeds 10 parts by mass, the second wall layer may become brittle and the strength of the second wall layer may be reduced.

  The method for adding the epoxy / melamine condensate to the aqueous medium may be added together with the epoxy compound or before or after the addition of the epoxy compound, and is not particularly limited. The epoxy compound is added in the form of an aqueous solution to the aqueous medium in which the microcapsules whose contents are encapsulated in the first wall layer are dispersed, and after a while, the epoxy-melamine condensate is added in the form of an aqueous solution. It is preferable. When the cross-linking agent is reacted, it is preferable that the cross-linking agent is added dropwise in the form of an aqueous solution after adding a little time after the epoxy / melamine cross-linking agent is added in the form of an aqueous solution.

  Although the temperature at the time of forming a 2nd wall layer is not specifically limited, Preferably it is 10-150 degreeC, More preferably, it is 20-100 degreeC, More preferably, it is 30-80 degreeC. If the temperature at which the second wall layer is formed is less than 10 ° C., the reaction of the epoxy compound is slow, and the second wall layer may not be sufficiently formed. Conversely, if the temperature at which the second wall layer is formed exceeds 150 ° C., the formation of the second wall layer may be hindered. The time for forming the second wall layer is not particularly limited, and can be set as appropriate according to the amount charged and the temperature for forming the second wall layer. Within a few tens of hours. Generally, when the temperature when forming the second wall layer is low, the time when forming the second wall layer is lengthened, and conversely, when the temperature when forming the second wall layer is high, What is necessary is just to shorten the time at the time of forming a 2 wall layer.

  An aging period may be provided after forming the second wall layer. The temperature during aging is not particularly limited, but is preferably the same as or slightly higher than the temperature at which the second wall layer is formed. The aging time is not particularly limited, but is preferably 0.5 to 5 hours, more preferably 1 to 3 hours.

  As described above, when dispersing the hydrophobic contents in an aqueous medium, the present inventors have a specific structure having a polymer structure in which water-soluble monosaccharides such as galactose and arabinose are bound as a dispersant. It has been found that the use of polysaccharides (for example, soybean polysaccharide, gati gum) improves the solvent resistance of multilayer microcapsules. However, the present inventors have not only used these specific polysaccharides, but also formed the second wall layer even when using normal polysaccharides such as gum arabic. It was found that the solvent resistance of the multi-layer microcapsules is further improved by appropriately adjusting the temperature and time, and the subsequent aging temperature and aging time. Specifically, the multilayer microcapsules become resistant to isopropanol. In order to further improve the solvent resistance of the multilayer microcapsule, the temperature at the time of forming the second wall layer is set high within the above range and / or the temperature at the time of aging is formed at the second wall layer. What is necessary is just to set higher than the temperature at the time, and / or to set ripening time long within the said range.

  After forming the second wall layer, the obtained multilayer microcapsule may be separated from the aqueous medium by a conventionally known method such as suction filtration or natural filtration, if necessary. When the microcapsules are dried, for example, when the hydrophobic content contains a solvent, the multilayer microcapsules may be deformed by leaching and evaporating the solvent. It is preferable to attach to the next step without separation.

  The multilayer microcapsules obtained in the step of forming the second wall layer are preferably classified in order to obtain multilayer microcapsules having a narrow particle size distribution, and / or to improve the product quality by removing impurities. Furthermore, it is preferable to wash.

  Since the classification and washing of the multilayer microcapsules may be performed in the same manner as in the case of the microcapsules obtained in the step of forming the first wall layer, description thereof is omitted here.

<Formation of third and subsequent wall layers>
Next, when forming the third and subsequent wall layers, at least one third and subsequent wall layers are formed on the outer surface of the second wall layer by, for example, a coacervation method, an in-situ polymerization method, an interface weight. It is formed by a conventionally known method such as a combination method using the same material as the capsule shell in a conventionally known microcapsule. Examples of the material for forming the third and subsequent wall layers include the materials listed above as materials suitable for use in each method.

  The multilayer microcapsules obtained in the process of forming the third and subsequent wall layers are preferably classified in order to obtain multilayer microcapsules having a narrow particle size distribution and / or improve the product quality by removing impurities. For this purpose, it is preferable to wash.

  Since the classification and washing of the multilayer microcapsules may be performed in the same manner as in the case of the microcapsules obtained in the step of forming the first wall layer, description thereof is omitted here.

<Use of multilayer microcapsules>
In the production method of the present invention, the multilayer microcapsules are finally obtained in the form of a dispersion in an aqueous medium when the third and subsequent wall layers are not formed. When the third and subsequent wall layers are formed, although depending on the method of forming the third and subsequent wall layers, in many cases, it is finally obtained in the form of a dispersion in an aqueous medium. The obtained multilayer microcapsules may be used separately from the aqueous medium, but the dispersion is filtered using a conventionally known filtration device, and the content of the aqueous medium is preferably 15 to 45%, more preferably. Is preferably used in the form of a filter cake of 20-40%, more preferably 25-35%.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by the following examples, but may be appropriately modified within a range that can meet the purpose described above and below. It is also possible to implement, and they are all included in the technical scope of the present invention. In the following examples, “%” represents “mass%” in the case of concentration or solid content.

  First, a method for measuring the particle size of the microcapsule and a method for evaluating the solvent resistance (methanol resistance, ethanol resistance and isopropanol resistance) and heat resistance of the microcapsule will be described.

<Particle size of microcapsule>
The particle size of the microcapsules was measured by measuring the volume average particle size using a laser diffraction / scattering particle size distribution analyzer (product name: LA-910, manufactured by Horiba, Ltd.).

<Methanol resistance>
A sample tube with a capacity of 20 mL was charged with 3 g of microcapsule filter cake and 10 g of a mixed solvent of methanol / water = 8/2 (mass ratio), stirred for 30 minutes and allowed to stand for 24 hours. The state of the microcapsules after evaporation was observed with an optical microscope (digital microscope VHX-500, manufactured by Keyence Corporation; magnification 500 to 2,000 times), and the methanol resistance of the microcapsules was evaluated according to the following criteria.
A: No change is observed in the entire microcapsule;
○: There are some slightly depressed microcapsules, but most microcapsules have no change;
Δ: A slight dent is observed in the entire microcapsule;
X: Remarkable dent is recognized in the whole microcapsule, and most of the contents are missing.

<Ethanol tolerance>
In a sample tube with a capacity of 20 mL, 3 g of microcapsule filter cake and 10 g of a mixed solvent of ethanol / water = 8/2 (mass ratio) were placed, stirred for 30 minutes and allowed to stand for 24 hours. The state of the microcapsule after evaporation was observed with an optical microscope (digital microscope VHX-500, manufactured by Keyence Corporation; magnification: 500 to 2,000 times), and the ethanol resistance of the microcapsule was evaluated according to the following criteria.
A: No change is observed in the entire microcapsule;
○: There are some slightly depressed microcapsules, but most microcapsules have no change;
Δ: A slight dent is observed in the entire microcapsule;
X: Remarkable dent is recognized in the whole microcapsule, and most of the contents are missing.

<Isopropanol resistance>
In a sample tube with a capacity of 20 mL, 3 g of microcapsule filter cake and 10 g of a mixed solvent of isopropanol / water = 8/2 (mass ratio) were added, stirred for 30 minutes, allowed to stand for 24 hours, sampled microcapsules, solvent The state of the microcapsules after evaporation was observed with an optical microscope (digital microscope VHX-500, manufactured by Keyence Corporation; magnification 500 to 2,000 times), and the isopropanol resistance of the microcapsules was evaluated according to the following criteria.
A: No change is observed in the entire microcapsule;
○: There are some slightly depressed microcapsules, but most microcapsules have no change;
Δ: A slight dent is observed in the entire microcapsule;
X: Remarkable dent is recognized in the whole microcapsule, and most of the contents are missing.

<Heat resistance>
About 3 g of the microcapsule filter cake was dried with a dryer at 50 ° C., and the dried microcapsule cake was precisely weighed (the mass at this time is referred to as “mass a”). The sample was dried and taken out every 2 hours and weighed precisely (the masses at this time were “mass b1,” “mass b2,”...), And the loss on drying of the microcapsules was calculated according to the following formula.
Loss on drying (%) = [(mass a−mass b1 or mass b2...) / Mass a] × 100
The loss on drying of the microcapsules is considered to be caused by, for example, cracking of the microcapsules due to drying or increase in internal pressure, and leaching of the contents and evaporation.

  Next, a first wall layer material composed of an amino resin having a mercapto group, a second wall layer material composed of an epoxy resin, and a comparative wall layer composed of an amino resin having an ethylene oxide chain An example of material synthesis will be described.

<< Synthesis Example 1 >>
A 100 mL round bottom separable flask was charged with 8 g of melamine, 7 g of urea, 40 g of 37% formaldehyde aqueous solution and 2 g of 25% aqueous ammonia, and the temperature was raised to 70 ° C. while stirring. After maintaining at the same temperature for 1 hour, the mixture was cooled to 30 ° C. to obtain an aqueous solution (A-1) having a solid content of 52.2% containing a melamine / urea / formaldehyde initial condensate.

<< Synthesis Example 2 >>
A 100 mL round bottom separable flask was charged with 8 g of melamine, 2 g of benzoguanamine, 5 g of urea, 30 g of 37% formaldehyde aqueous solution and 3 g of 25% aqueous ammonia, and the temperature was raised to 75 ° C. while stirring. After maintaining at the same temperature for 15 minutes, it was cooled to 30 ° C. to obtain an aqueous solution (A-2) having a solid content of 54.4% containing melamine / benzoguanamine / urea / formaldehyde precondensate.

<< Synthesis Example 3 >>
A 100 mL round bottom separable flask was charged with 15 g of melamine, 40 g of 37% formaldehyde aqueous solution, and 2 g of 10% sodium carbonate aqueous solution, and the temperature was raised to 70 ° C. while stirring. After maintaining at the same temperature for 20 minutes, it was cooled to 30 ° C. to obtain an aqueous solution (A-3) having a solid content of 52.6% containing a melamine / formaldehyde initial condensate.

<< Synthesis Example 4 >>
125 g of polyglycerol polyglycidyl ether (trade name: Denacol EX-521 (mass average molecular weight of 732, solubility rate in water of 100%), manufactured by Nagase ChemteX Corporation) as an epoxy compound in a four-necked separable flask with a capacity of 300 mL Then, 125 g of water was charged and dissolved by stirring. 50 g of 50% urea aqueous solution was added thereto and reacted at 40 ° C. for 1 hour to obtain an aqueous solution (B-1) having a solid content of 50% containing a compound obtained by reacting an epoxy compound and urea.

  A 100 mL four-necked separable flask was charged with 3 g of melamine, 20 g of a 37% formaldehyde aqueous solution, and 2 g of 25% aqueous ammonia, and reacted at 70 ° C. for 20 minutes, to which 24 g of an aqueous solution (B-1) was added, The reaction was further carried out at the same temperature for 15 minutes, and the mixture was cooled to 25 ° C. to obtain an aqueous solution (B-2) having a solid content of 45.7% containing a melamine / urea / formaldehyde initial condensate.

<< Synthesis Example 5 >>
A separable flask having a capacity of 300 mL was charged with 14.5 g of polyethyleneimine (trade name: Epomin SP006 (mass average molecular weight 600), manufactured by Nippon Shokubai Co., Ltd.) and 36.4 g of water, and prepared in advance while stirring. Epoxy compound lauryl alcohol polyoxyethylene (EO addition number 22) glycidyl ether (developed product: Denacol FCA-014 (mass average molecular weight 1,279, solubility in water 100%), manufactured by Nagase ChemteX Corporation ) An aqueous solution obtained by dissolving 24.3 g in 80 g of water was added dropwise over 10 minutes. In addition, the liquid temperature at the time of dripping was kept at 25 degrees C or less. After completion of dropping, the mixture was continuously stirred for 30 minutes, then heated to 70 ° C., held for 2 hours, cooled to room temperature, and a solid content of 25% containing a compound obtained by reacting polyethyleneimine and an epoxy compound. An aqueous solution (CA-1) was obtained.

  Next, a multilayer microcapsule in which a hydrophobic content is encapsulated in a shell having a first wall layer composed of an amino resin having a mercapto group and a second wall layer composed of an epoxy resin, and for comparison A manufacturing example of a microcapsule will be described.

Example 1
120 g of aqueous solution in which 20 g of gum arabic is dissolved in a 500 mL flat bottom separable flask, and using a disper (product name: ROBOMICS, manufactured by Tokushu Kika Kogyo Co., Ltd.), is a heat storage agent while stirring at 350 rpm. Add 100 g of dimethyl silicone oil (trade name: KF-96L-2CS, manufactured by Shin-Etsu Chemical Co., Ltd.), then change the stirring speed to 1,800 rpm and stir for 2 minutes, then set the stirring speed to 1,000 rpm. Changed and added 100 g of water to obtain a suspension.

  This suspension was placed in a four-necked separable flask having a capacity of 300 mL equipped with a thermometer and a cooling tube, and 57 g of aqueous solution (A-1) was added while stirring at a paddle blade while maintaining at 40 ° C. . After 15 minutes, 100 g of an aqueous solution in which 3 g of L-cysteine was dissolved was dropped with a dropping funnel over 5 minutes. The reaction was carried out for 4 hours while maintaining the temperature at 40 ° C., then the temperature was raised to 50 ° C. and aging was performed for 2 hours. Dimethyl silicone oil was encapsulated in the first wall layer composed of an amino resin having a mercapto group. A microcapsule dispersion was obtained.

  The obtained dispersion was cooled to 25 ° C., and coarse capsules were removed with a standard sieve having an opening of 75 μm. Next, the microcapsule dispersion was put into a 2 L beaker, and water was added to make a total volume of 1,000 mL. The microcapsule was allowed to settle as it was, and the supernatant was discarded. This operation was repeated three times to wash the microcapsules.

  Next, water was added to the microcapsules to make a 200 g dispersion, which was transferred to a 500 mL flat bottom separable flask and heated to 40 ° C. with stirring.

  To this microcapsule dispersion, 10 g of polyglycerol polyglycidyl ether (trade name: Denacol EX-521 (mass average molecular weight of 732, solubility in water of 100%), manufactured by Nagase ChemteX Corporation) as an epoxy compound and polypropylene glycol 100 g of an aqueous solution in which 5 g of diglycidyl ether (trade name: Denacol EX-920 (mass average molecular weight 286, dissolution rate with respect to water 100%), manufactured by Nagase ChemteX Corporation) was dissolved was added. After 30 minutes, 50 g of an aqueous solution in which 2 g of sodium diethyldithiocarbamate was dissolved was added dropwise over 5 minutes with a dropping funnel. The reaction is carried out for 3 hours while maintaining 40 ° C., then the temperature is raised to 50 ° C. and aging is carried out for 1 hour. A dispersion of microcapsules in which dimethyl silicone oil as a heat storage agent was encapsulated in the shell formed with the second wall layer was obtained.

  The obtained dispersion was cooled to 25 ° C., and coarse capsules were removed with a standard sieve having an opening of 53 μm. Next, the microcapsule dispersion was put into a 2 L beaker, and water was added to make a total volume of 1,000 mL. The microcapsule was allowed to settle as it was, and the supernatant was discarded. This operation was repeated three times to wash the microcapsules.

  The particle diameter of the thus obtained microcapsules (1) was measured, and it was found that the volume average particle diameter was 21.2 μm.

  The microcapsule (1) was subjected to suction filtration to obtain a filter cake having a solid content of 61%. Using this filter cake, the solvent resistance (methanol resistance) and heat resistance of the microcapsule (1) were evaluated. The results are shown in Table 1.

<< Example 2 >>
In Example 1, instead of dimethyl silicone oil, using dioctyl phthalate as a plasticizer, changing the stirring speed of 1,800 rpm with a disper to 1,600 rpm, obtaining a suspension; and the first wall A first resin composed of an amino resin having a mercapto group in the same manner as in Example except that 48 g of the aqueous solution (A-2) was used instead of 57 g of the aqueous solution (A-1) for forming the layer. A microcapsule dispersion in which dioctyl phthalate was encapsulated in a shell having a second wall layer made of an epoxy resin formed on the outer surface of the wall layer was obtained.

  The obtained dispersion was cooled to 25 ° C., and subjected to microcapsule classification and washing steps in the same manner as in Example 1.

  The particle diameter of the thus obtained microcapsules (2) was measured, and it was found that the volume average particle diameter was 40.6 μm.

  The microcapsule (2) was subjected to suction filtration to obtain a filter cake having a solid content of 62%. Using this filter cake, the solvent resistance (methanol resistance) and heat resistance of the microcapsule (2) were evaluated. The results are shown in Table 1.

Example 3
In Example 1, instead of 57 g of the aqueous solution (A-1) for forming the first wall layer, 85.5 g of the aqueous solution (A-3) was used, and after adding the aqueous solution of the epoxy compound, After 15 minutes, 49 g of the aqueous solution (B-2) was added, and 30 minutes later, 50 g of an aqueous solution in which 3 g of sodium diethyldithiocarbamate was dissolved was added dropwise over 5 minutes using the dropping funnel. Dimethylsilicone oil, which is a heat storage agent, was encapsulated in a shell in which a second wall layer composed of a melamine-crosslinked epoxy resin was formed on the outer surface of the first wall layer composed of an amino resin having a mercapto group. A microcapsule dispersion was obtained.

  The obtained dispersion was cooled to 25 ° C., and subjected to microcapsule classification and washing steps in the same manner as in Example 1.

  The particle diameter of the thus obtained microcapsule (3) was measured, and the volume average particle diameter was 22.0 μm.

  The microcapsule (3) was subjected to suction filtration to obtain a filter cake having a solid content of 57%. Using this filter cake, the solvent resistance (methanol resistance) and heat resistance of the microcapsule (3) were evaluated. The results are shown in Table 1.

≪Comparative example 1≫
In a 500 mL flat bottom separable flask, 60 g of water, 6 g of gum arabic, and 6 g of gelatin were charged and dissolved. While maintaining this solution at 43 ° C., 100 g of dioctyl phthalate heated to 50 ° C. was added while stirring at 400 rpm using a disper (product name: ROBOMICS, manufactured by Tokushu Kika Kogyo Co., Ltd.). . Thereafter, the stirring speed was set to 1,800 rpm, and after stirring for 2 minutes, the stirring speed was set to 1,000 rpm, and 300 mL of hot water at 43 ° C. was added to obtain a suspension.

  Stirring was changed to stirring with a paddle blade, a thermometer and a pH meter were set, and the temperature was maintained at 40 ° C. while stirring the whole.

  Subsequently, 10% aqueous acetic acid was gradually added dropwise to adjust the pH to 4.3. After confirming the precipitation of gelatin / gum arabic and the formation of microcapsules with an optical microscope, the mixture was cooled to 10 ° C.

  After maintaining in a cooled state for 30 minutes, 3 mL of 37% formalin aqueous solution was added, 10% sodium carbonate aqueous solution was gradually added dropwise to adjust the pH to 8.8, and then the temperature was raised to 30 ° C. and maintained for 2 hours. The temperature was further raised to 40 ° C. and the mixture was aged for 1 hour, then cooled to 25 ° C., and the coarse capsules were removed with a standard sieve having an opening of 53 μm. Next, the microcapsule dispersion was put into a 2 L beaker, and water was added to make the total volume 1,000 ml. The microcapsule was allowed to settle as it was, and the supernatant was discarded. This operation was repeated three times to wash the microcapsules.

  When the particle diameter of the comparative microcapsule (C1) obtained in this manner was measured, the volume average particle diameter was 35.2 μm.

  The comparative microcapsule (C1) was subjected to suction filtration to obtain a filter cake having a solid content of 51%. Using this filter cake, the solvent resistance (methanol resistance) and heat resistance of the comparative microcapsule (C1) were evaluated. The results are shown in Table 1.

≪Comparative example 2≫
A 500 mL flat bottom separable flask was charged with 40 g of aqueous solution (CA-1) and 60 g of water, and dimethyl silicone was stirred at 350 rpm using a disper (product name: ROBOMICS, manufactured by Tokushu Kika Kogyo Co., Ltd.). After adding 100 g of oil (trade name: KF-96L-2CS, manufactured by Shin-Etsu Chemical Co., Ltd.), the mixture was stirred at 1,200 rpm for 3 minutes. The stirring speed was 800 rpm and 50 g of water was added to obtain a suspension.

  This suspension was put into a 500 mL four-necked separable flask equipped with a thermometer and a condenser, and 32 g of the aqueous solution (A-1) was added while stirring with a paddle blade, at 35 ° C. for 2 hours. Reaction was carried out at 70 ° C. for 2 hours to obtain a microcapsule dispersion in which dimethyl silicone oil as a heat storage agent was encapsulated in a shell composed of an amino resin having an ethylene oxide chain.

  The obtained dispersion was cooled to 25 ° C., and coarse capsules were removed with a standard sieve having an opening of 53 μm. Next, the microcapsule dispersion was put into a 2 L beaker, and water was added to make a total volume of 1,000 mL. The microcapsule was allowed to settle as it was, and the supernatant was discarded. This operation was repeated three times to wash the microcapsules.

  When the particle diameter of the comparative microcapsule (C2) obtained in this manner was measured, the volume average particle diameter was 30.3 μm.

  The comparative microcapsule (C2) was subjected to suction filtration to obtain a filter cake having a solid content of 66.1%. Using this filter cake, the solvent resistance (methanol resistance) and heat resistance of the comparative microcapsule (C2) were evaluated. The results are shown in Table 1.

«Comparative Example 3»
A 500 mL flat bottom separable flask was charged with 40 g of aqueous solution (CA-1) and 60 g of water, and dimethyl silicone was stirred at 350 rpm using a disper (product name: ROBOMICS, manufactured by Tokushu Kika Kogyo Co., Ltd.). After adding 100 g of oil (trade name: KF-96L-2CS, manufactured by Shin-Etsu Chemical Co., Ltd.), the mixture was stirred at 1,200 rpm for 3 minutes. The stirring speed was 800 rpm and 50 g of water was added to obtain a suspension.

  This suspension was put into a 500 mL four-necked separable flask equipped with a thermometer and a condenser, and 57 g of aqueous solution (A-1) was added while stirring with a paddle blade, and the temperature was raised to 35 ° C. The mixture was kept at the same temperature for 2 hours to obtain a microcapsule dispersion in which dimethyl silicone oil was encapsulated in a very thin first wall layer composed of an amino resin having an ethylene oxide chain.

  Further, while maintaining 35 ° C., 10 g of polyglycerol polyglycidyl ether (trade name: Denacol EX521 (mass average molecular weight 732, solubility in water 100%), manufactured by Nagase ChemteX Corp.) and polypropylene glycol diglycidyl ether (product) Name: Denacor EX-920, manufactured by Nagase ChemteX Corporation) 5 g in an aqueous solution was added dropwise over 10 minutes. Next, an aqueous solution in which 2 g of sodium diethyldithiocarbamate trihydrate was dissolved in 50 g of water was added dropwise over 10 minutes. A shell in which a second wall layer made of an epoxy resin is formed on the outer surface of the first wall layer made of a melamine resin having an ethylene oxide chain by reacting at the same temperature for 2 hours at 70 ° C. A dispersion of microcapsules encapsulating dimethyl silicone oil as a heat storage agent was obtained.

  The obtained dispersion was cooled to 25 ° C., and coarse capsules were removed with a standard sieve having an opening of 53 μm. Next, the microcapsule dispersion was put into a 2 L beaker, and water was added to make a total volume of 1,000 mL. The microcapsule was allowed to settle as it was, and the supernatant was discarded. This operation was repeated three times to wash the microcapsules.

  When the particle diameter of the comparative microcapsule (C3) obtained in this way was measured, the volume average particle diameter was 30.0 μm.

  The comparative microcapsule (C3) was subjected to suction filtration to obtain a filter cake having a solid content of 65%. Using this filter cake, the solvent resistance (methanol resistance) and heat resistance of the comparative microcapsule (C3) were evaluated. The results are shown in Table 1.

<< Comparative Example 4 >>
In Example 1, except that 100 g of an aqueous solution in which 3 g of L-cysteine was dissolved was not added, the outer surface of the first wall layer composed of an amino resin having no mercapto group was formed in the same manner as in Example 1. A microcapsule dispersion was obtained in which dimethyl silicone oil as a heat storage agent was encapsulated in a shell formed with a second wall layer composed of an epoxy resin. In this comparative example, many transparent particles having a particle diameter of about several μm to 10 μm were observed, but these transparent particles are considered to be particles made of an epoxy resin constituting the second wall layer. Such transparent particles were not observed in Examples 1 to 3.

  The obtained dispersion was cooled to 25 ° C., and coarse capsules were removed with a standard sieve having an opening of 53 μm. Next, the microcapsule dispersion was put into a 2 L beaker, and water was added to make a total volume of 1,000 mL. The microcapsule was allowed to settle as it was, and the supernatant was discarded. This operation was repeated three times to wash the microcapsules.

  When the particle diameter of the comparative microcapsule (C4) obtained in this way was measured, the volume average particle diameter was 21.5 μm.

  The comparative microcapsule (C4) was subjected to suction filtration to obtain a filter cake having a solid content of 60%. Using this filter cake, the solvent resistance (methanol resistance) and heat resistance of the comparative microcapsule (C4) were evaluated. The results are shown in Table 1.

<< Comparative Example 5 >>
In Example 1, before adding an epoxy compound, the microcapsule was taken out and used as a comparative microcapsule (C5).

  When the particle diameter of the comparative microcapsule (C5) obtained in this manner was measured, the volume average particle diameter was 22.1 μm.

  The comparative microcapsule (C5) was subjected to suction filtration to obtain a filter cake having a solid content of 61%. Using this filter cake, the solvent resistance (methanol resistance) and heat resistance of the comparative microcapsule (C5) were evaluated. The results are shown in Table 1.

  As is clear from Table 1, the microcapsules of Examples 1 to 3 have a first wall layer made of an amino resin having a mercapto group and a second wall layer made of an epoxy resin. In addition to high solvent resistance, the value of loss on drying after 2 to 6 hours was very small, indicating high heat resistance. In particular, the microcapsules of Example 3 had higher performance than the microcapsules of Examples 1 and 2 because the second wall layer was composed of an epoxy resin having a melamine cross-linked.

  On the other hand, since the microcapsules of Comparative Examples 1 to 3 have shells made of conventional materials, they exhibit lower solvent resistance than the microcapsules of Examples 1 to 3, and after 2 hours. The value of loss on drying until after 6 hours was large, indicating low heat resistance. In particular, since the microcapsule of Comparative Example 1 has a shell composed of gelatin / gum arabic, it exhibits extremely low solvent resistance and has a very large loss on drying value from 2 hours to 6 hours. It showed very low heat resistance. The microcapsule of Comparative Example 4 has a thin first wall layer made of an amino resin not having a mercapto group and a thin second wall layer made of an epoxy resin. Since the wall layer is not bonded to each other, the capsule strength is low, the solvent resistance is very low, and the loss on drying from 2 hours to 6 hours is relatively large, indicating relatively low heat resistance. It was. Furthermore, since the microcapsule of Comparative Example 5 has a thick shell composed of an amino resin having a mercapto group, the capsule strength was high and the solvent resistance was relatively high. Was large and showed low heat resistance.

  Thus, if a shell having a first wall layer composed of an amino resin having a mercapto group and a second wall layer composed of an epoxy resin is used, the contents are excellent in impermeability and have high mechanical strength. It can be seen that multilayer microcapsules having high solvent resistance and high heat resistance can be obtained.

  Next, when dispersing hydrophobic contents in an aqueous medium, a multilayer microcapsule that exhibits high heat resistance and improved solvent resistance by using a polysaccharide such as soybean polysaccharide or gati gum as a dispersant. An example of production will be described.

Example 4
A 500 mL flat bottom separable flask was charged with 120 g of an aqueous solution in which 12 g of soybean polysaccharide (trade name: Soya Five-S-LNP, manufactured by Fuji Oil Co., Ltd.) was dissolved, and Disper (ROBOMICS, Special Machine Industries, Ltd.). And 100 g of dimethyl silicone oil (trade name: KF-96L-2CS, manufactured by Shin-Etsu Chemical Co., Ltd.) as a heat storage agent is added while stirring at 600 rpm, and then the stirring speed is increased to 1,600 rpm. After changing and stirring for 2 minutes, the stirring speed was changed to 1,000 rpm, and 100 g of water was added to obtain a suspension.

  This suspension was placed in a four-necked separable flask having a capacity of 300 mL equipped with a thermometer and a condenser, and 48 g of aqueous solution (A-1) was added while stirring at a paddle blade while maintaining at 40 ° C. . After 15 minutes, 100 g of an aqueous solution in which 2 g of L-cysteine was dissolved was dropped over 5 minutes with a dropping funnel. The reaction was carried out for 4 hours while maintaining 40 ° C., then heated to 50 ° C. and aged for 2 hours, and dimethyl silicone as a heat storage agent was formed on the first wall layer composed of an amino resin having a mercapto group. A dispersion of microcapsules encapsulating oil was obtained.

  The obtained dispersion was cooled to 25 ° C., and coarse capsules were removed with a standard sieve having an opening of 75 μm. Next, the microcapsule dispersion was put into a 2 L beaker, and water was added to make a total volume of 1,000 mL. The microcapsule was allowed to settle as it was, and the supernatant was discarded. This operation was repeated three times to wash the microcapsules.

  Next, water was added to the microcapsules to make a 200 g dispersion, which was transferred to a 500 mL flat bottom separable flask and heated to 40 ° C. with stirring.

  In this microcapsule dispersion, 15 g of polyglycerol polyglycidyl ether (trade name: Denacol EX-521 (mass average molecular weight 732, solubility in water 100%), manufactured by Nagase ChemteX Corporation), which is an epoxy compound, was dissolved. 100 g of an aqueous solution was added. After 30 minutes, 50 g of an aqueous solution in which 2 g of sodium diethyldithiocarbamate was dissolved was added dropwise over 5 minutes with a dropping funnel. The reaction is carried out for 3 hours while maintaining 40 ° C., then the temperature is raised to 50 ° C. and aging is carried out for 1 hour. A dispersion of microcapsules in which dimethyl silicone oil as a heat storage agent was encapsulated in the shell formed with the second wall layer was obtained.

  The obtained dispersion was cooled to 25 ° C., and coarse capsules were removed with a standard sieve having an opening of 53 μm. Next, the microcapsule dispersion was put into a 2 L beaker, and water was added to make a total volume of 1,000 mL. The microcapsule was allowed to settle as it was, and the supernatant was discarded. This operation was repeated three times to wash the microcapsules.

  The particle diameter of the thus obtained microcapsule (4) was measured, and it was found that the volume average particle diameter was 39.8 μm.

  The microcapsule (4) was subjected to suction filtration to obtain a filter cake having a solid content of 60%. Using this filter cake, the solvent resistance (ethanol resistance) and heat resistance of the microcapsule (4) were evaluated. The results are shown in Table 2.

Example 5
In Example 4, the soybean polysaccharide was changed to (trade name: Soya Five-S-DN, manufactured by Fuji Oil Co., Ltd.), the stirring speed by disperser 1,600 rpm was changed to 1,800 rpm, and the suspension In the same manner as in Example 4 except that the aqueous solution (A-2) was used instead of the aqueous solution (A-1) for forming the first wall layer, the microcapsule ( 5) was obtained.

  The particle diameter of the thus obtained microcapsule (5) was measured, and it was found that the volume average particle diameter was 40.5 μm. Moreover, it carried out similarly to Example 4, and evaluated solvent resistance (ethanol tolerance) and heat resistance of the obtained microcapsule (5). The results are shown in Table 2.

Example 6
In Example 4, the soybean polysaccharide was changed to (trade name: Soya Five-S-HR100, manufactured by Fuji Oil Co., Ltd.), instead of the aqueous solution (A-1) for forming the first wall layer. The aqueous solution (A-3) was used, and 15 minutes after the addition of the epoxy compound, 49 g of the aqueous solution (B-2) was added, and 30 minutes later, 50 g of the aqueous solution in which 1 g of sodium diethyldithiocarbamate was dissolved was added. A microcapsule (6) was obtained in the same manner as in Example 4 except that it was dropped over 5 minutes with a dropping funnel.

  When the particle diameter of the thus obtained microcapsules (6) was measured, the volume average particle diameter was 38.2 μm. Moreover, it carried out similarly to Example 4, and evaluated solvent tolerance (ethanol tolerance) and heat resistance of the obtained microcapsule (6). The results are shown in Table 2.

Example 7
A microcapsule (7) was obtained in the same manner as in Example 4 except that the soybean polysaccharide was changed to (trade name: Soya Five-S-ZR100, manufactured by Fuji Oil Co., Ltd.) in Example 4. .

  The particle diameter of the thus obtained microcapsules (7) was measured, and it was found that the volume average particle diameter was 35.9 μm. Moreover, it carried out similarly to Example 4, and evaluated the solvent tolerance (ethanol tolerance) and heat resistance of the obtained microcapsule (7). The results are shown in Table 2.

Example 8
In Example 4, the soybean polysaccharide was changed to (trade name: Soya Five-S-LN, manufactured by Fuji Oil Co., Ltd.), the stirring speed by the disper 1,600 rpm was changed to 1,800 rpm, and the suspension In the same manner as in Example 4 except that the aqueous solution (A-2) was used instead of the aqueous solution (A-1) for forming the first wall layer, the microcapsule ( 8) was obtained.

  The particle diameter of the thus obtained microcapsules (8) was measured, and it was found that the volume average particle diameter was 44.4 μm. Moreover, it carried out similarly to Example 4, and evaluated the solvent tolerance (ethanol tolerance) and heat resistance of the obtained microcapsule (8). The results are shown in Table 2.

Example 9
In Example 4, the soybean polysaccharide was changed to (trade name: Soya Five-S-EN100, manufactured by Fuji Oil Co., Ltd.), instead of the aqueous solution (A-1) for forming the first wall layer. The aqueous solution (A-3) was used, and 15 minutes after the addition of the epoxy compound, 49 g of the aqueous solution (B-2) was added, and 30 minutes later, 50 g of the aqueous solution in which 1 g of sodium diethyldithiocarbamate was dissolved was added. A microcapsule (9) was obtained in the same manner as in Example 4 except that it was dropped over 5 minutes with a dropping funnel.

  The particle diameter of the thus obtained microcapsules (9) was measured, and it was found that the volume average particle diameter was 42.7 μm. Moreover, it carried out similarly to Example 4, and evaluated solvent resistance (ethanol tolerance) and heat resistance of the obtained microcapsule (9). The results are shown in Table 2.

Example 10
A microcapsule (10) was prepared in the same manner as in Example 4 except that the soybean polysaccharide was changed to (trade name: SM-700, manufactured by San-Ei Gen FFI Co., Ltd.) in Example 4. Obtained.

  The particle diameter of the thus obtained microcapsules (10) was measured, and it was found that the volume average particle diameter was 50.1 μm. Moreover, it carried out similarly to Example 4, and evaluated solvent tolerance (ethanol tolerance) and heat resistance of the obtained microcapsule (10). The results are shown in Table 2.

Example 11
In Example 4, the soybean polysaccharide was changed to (trade name: SM-1200, manufactured by San-Ei Gen FFI Co., Ltd.), and the stirring speed of 1,600 rpm by the disper was changed to 1,800 rpm. In the same manner as in Example 4, except that the turbid liquid was obtained and the aqueous solution (A-2) was used instead of the aqueous solution (A-1) for forming the first wall layer. Capsules (11) were obtained.

  The particle diameter of the thus obtained microcapsule (11) was measured, and it was found that the volume average particle diameter was 41.3 μm. Moreover, it carried out similarly to Example 4, and evaluated solvent tolerance (ethanol tolerance) and heat resistance of the obtained microcapsule (11). The results are shown in Table 2.

<< Example 12 >>
In Example 4, it replaced with the polysaccharide (brand name: Gati Gum SD, San-Ei Gen FFI Co., Ltd. product) instead of soybean polysaccharide, and the aqueous solution (A- for forming the first wall layer) In place of 1), the aqueous solution (A-3) was used, and 15 minutes after the addition of the epoxy compound, 49 g of the aqueous solution (B-2) was added. 30 minutes later, 1 g of sodium diethyldithiocarbamate was added. A microcapsule (12) was obtained in the same manner as in Example 4 except that 50 g of the dissolved aqueous solution was dropped with a dropping funnel over 5 minutes.

  The particle diameter of the thus obtained microcapsule (12) was measured, and it was found that the volume average particle diameter was 42.6 μm. Moreover, it carried out similarly to Example 4, and evaluated the solvent tolerance (ethanol tolerance) and heat resistance of the obtained microcapsule (12). The results are shown in Table 2.

  As is clear from Table 2, since the microcapsules of Examples 4 to 12 used soy polysaccharide or gati gum as a dispersant when dispersing the hydrophobic contents in the aqueous medium, the microcapsules were used after 2 hours. The value of loss on drying after 6 hours is very small, showing high heat resistance and high resistance to ethanol, and the solvent resistance is improved compared to the case of using gum arabic.

  Thus, when dispersing a hydrophobic content in an aqueous medium, if a polysaccharide such as soybean polysaccharide or gati gum is used as a dispersant, a normal polysaccharide such as gum arabic can be used in addition to high heat resistance. It can be seen that multilayer microcapsules with improved solvent resistance can be obtained compared to the case of

  Next, when the hydrophobic content is dispersed in the aqueous medium, the encapsulation temperature and time (that is, the initial stage for forming the first wall layer) can be used even if a normal polysaccharide such as gum arabic is used as a dispersant. Reaction temperature and reaction time when performing condensation reaction of the condensate, temperature and time for subsequent aging, temperature and time for forming the second wall layer, temperature and time for subsequent aging) A production example of a multilayer microcapsule having high heat resistance and further improved solvent resistance will be described by appropriately adjusting.

Example 13
It is a heat storage agent while stirring at 600 rpm using a disper (product name: ROBOMICS, manufactured by Tokushu Kika Kogyo Co., Ltd.) in a 500 mL flat bottom separable flask, charged with 120 g of an aqueous solution in which 20 g of gum arabic is dissolved. Add 100 g of dimethyl silicone oil (trade name: KF-96L-2CS, manufactured by Shin-Etsu Chemical Co., Ltd.), then change the stirring speed to 1,600 rpm and stir for 2 minutes, then set the stirring speed to 1,000 rpm. Changed and added 100 g of water to obtain a suspension.

  This suspension was placed in a four-necked separable flask having a capacity of 300 mL equipped with a thermometer and a condenser, and 48 g of aqueous solution (A-1) was added while stirring at a paddle blade while maintaining at 40 ° C. . After 15 minutes, 100 g of an aqueous solution in which 2 g of L-cysteine was dissolved was dropped over 5 minutes with a dropping funnel. The reaction was carried out for 2 hours while maintaining 40 ° C., then heated to 60 ° C. and aged for 2 hours, and further heated to 80 ° C. and aged for 2 hours to obtain an amino resin having a mercapto group. A dispersion of microcapsules in which dimethyl silicone oil, which is a heat storage agent, was encapsulated in the first wall layer constituted by:

  The obtained dispersion was cooled to 25 ° C., and coarse capsules were removed with a standard sieve having an opening of 75 μm. Next, the microcapsule dispersion was put into a 2 L beaker, and water was added to make the total volume 1,000 ml. The microcapsule was allowed to settle as it was, and the supernatant was discarded. This operation was repeated three times to wash the microcapsules.

  Next, water was added to the microcapsules to make a 200 g dispersion, which was transferred to a 500 mL flat bottom separable flask and heated to 40 ° C. with stirring.

  In this microcapsule dispersion, 15 g of polyglycerol polyglycidyl ether (trade name: Denacol EX-521 (mass average molecular weight 732, solubility in water 100%), manufactured by Nagase ChemteX Corporation), which is an epoxy compound, was dissolved. 100 g of an aqueous solution was added. After 30 minutes, 50 g of an aqueous solution in which 2 g of sodium diethyldithiocarbamate was dissolved was added dropwise over 5 minutes with a dropping funnel. The reaction is carried out for 2 hours while maintaining 40 ° C., then the temperature is raised to 60 ° C. and aging is carried out for 2 hours, and the outer surface of the first wall layer made of an amino resin having a mercapto group is made of an epoxy resin. A dispersion of microcapsules in which dimethyl silicone oil as a heat storage agent was encapsulated in the shell formed with the second wall layer was obtained.

  The obtained dispersion was cooled to 25 ° C., and coarse capsules were removed with a standard sieve having an opening of 53 μm. Next, the microcapsule dispersion was put into a 2 L beaker, and water was added to make the total volume 1,000 ml. The microcapsule was allowed to settle as it was, and the supernatant was discarded. This operation was repeated three times to wash the microcapsules.

  When the particle diameter of the thus obtained microcapsules (13) was measured, the volume average particle diameter was 40.1 μm.

  The microcapsule (13) was subjected to suction filtration to obtain a filter cake having a solid content of 65%. Using this filter cake, the solvent resistance (isopropanol resistance) and heat resistance of the microcapsule (13) were evaluated. The results are shown in Table 3.

<< Example 14 >>
It is a heat storage agent while stirring at 600 rpm using a disper (product name: ROBOMICS, manufactured by Tokushu Kika Kogyo Co., Ltd.) in a 500 mL flat bottom separable flask, charged with 120 g of an aqueous solution in which 20 g of gum arabic is dissolved. Add 100 g of dimethyl silicone oil (trade name: KF-96L-2CS, manufactured by Shin-Etsu Chemical Co., Ltd.), then change the stirring speed to 1,600 rpm and stir for 2 minutes, then set the stirring speed to 1,000 rpm. Changed and added 100 g of water to obtain a suspension.

  This suspension was placed in a four-necked separable flask having a capacity of 300 mL equipped with a thermometer and a condenser, and 48 g of an aqueous solution (A-1) was added while stirring at a paddle blade while maintaining the temperature at 60 ° C. . After 15 minutes, 100 g of an aqueous solution in which 2 g of L-cysteine was dissolved was dropped over 5 minutes with a dropping funnel. The reaction was carried out for 4 hours while maintaining 60 ° C., then heated to 80 ° C. and aged for 2 hours, and dimethyl silicone as a heat storage agent was formed on the first wall layer composed of an amino resin having a mercapto group. A dispersion of microcapsules encapsulating oil was obtained.

  The obtained dispersion was cooled to 25 ° C., and coarse capsules were removed with a standard sieve having an opening of 75 μm. Next, the microcapsule dispersion was put into a 2 L beaker, and water was added to make the total volume 1,000 ml. The microcapsule was allowed to settle as it was, and the supernatant was discarded. This operation was repeated three times to wash the microcapsules.

  Next, water was added to the microcapsules to make a 200 g dispersion, which was transferred to a 500 mL flat bottom separable flask and heated to 40 ° C. with stirring.

  In this microcapsule dispersion, 15 g of polyglycerol polyglycidyl ether (trade name: Denacol EX-521 (mass average molecular weight 732, solubility in water 100%), manufactured by Nagase ChemteX Corporation), which is an epoxy compound, was dissolved. 100 g of an aqueous solution was added. After 30 minutes, 50 g of an aqueous solution in which 2 g of sodium diethyldithiocarbamate was dissolved was added dropwise over 5 minutes with a dropping funnel. The reaction is carried out for 2 hours while maintaining 40 ° C., then the temperature is raised to 60 ° C. and aging is carried out for 2 hours, and the outer surface of the first wall layer made of an amino resin having a mercapto group is made of an epoxy resin. A dispersion of microcapsules in which dimethyl silicone oil as a heat storage agent was encapsulated in the shell formed with the second wall layer was obtained.

  The obtained dispersion was cooled to 25 ° C., and coarse capsules were removed with a standard sieve having an opening of 53 μm. Next, the microcapsule dispersion was put into a 2 L beaker, and water was added to make the total volume 1,000 ml. The microcapsule was allowed to settle as it was, and the supernatant was discarded. This operation was repeated three times to wash the microcapsules.

  The particle diameter of the thus obtained microcapsule (14) was measured, and it was found that the volume average particle diameter was 45.3 μm. Moreover, it carried out similarly to Example 13, and evaluated solvent tolerance (isopropanol tolerance) and heat resistance of the obtained microcapsule (14). The results are shown in Table 3.

Example 15
It is a heat storage agent while stirring at 600 rpm using a disper (product name: ROBOMICS, manufactured by Tokushu Kika Kogyo Co., Ltd.) in a 500 mL flat bottom separable flask, charged with 120 g of an aqueous solution in which 20 g of gum arabic is dissolved. Add 100 g of dimethyl silicone oil (trade name: KF-96L-2CS, manufactured by Shin-Etsu Chemical Co., Ltd.), then change the stirring speed to 1,600 rpm and stir for 2 minutes, then set the stirring speed to 1,000 rpm. Changed and added 100 g of water to obtain a suspension.

  This suspension was placed in a four-necked separable flask having a capacity of 300 mL equipped with a thermometer and a condenser, and 48 g of aqueous solution (A-1) was added while stirring at a paddle blade while maintaining at 40 ° C. . After 15 minutes, 100 g of an aqueous solution in which 2 g of L-cysteine was dissolved was dropped over 5 minutes with a dropping funnel. The reaction was carried out for 4 hours while maintaining 40 ° C., then heated to 60 ° C. and aged for 2 hours, and dimethyl silicone as a heat storage agent was formed on the first wall layer composed of an amino resin having a mercapto group. A dispersion of microcapsules encapsulating oil was obtained.

  The obtained dispersion was cooled to 25 ° C., and coarse capsules were removed with a standard sieve having an opening of 75 μm. Next, the microcapsule dispersion was put into a 2 L beaker, and water was added to make the total volume 1,000 ml. The microcapsule was allowed to settle as it was, and the supernatant was discarded. This operation was repeated three times to wash the microcapsules.

  Next, water was added to the microcapsules to form a 200 g dispersion, which was transferred to a 300 mL flat bottom separable flask and heated to 40 ° C. with stirring.

  In this microcapsule dispersion, 15 g of polyglycerol polyglycidyl ether (trade name: Denacol EX-521 (mass average molecular weight 732, solubility in water 100%), manufactured by Nagase ChemteX Corporation), which is an epoxy compound, was dissolved. 100 g of an aqueous solution was added. After 30 minutes, 50 g of an aqueous solution in which 2 g of sodium diethyldithiocarbamate was dissolved was added dropwise over 5 minutes with a dropping funnel. The reaction is carried out for 2 hours while maintaining 60 ° C., then the temperature is raised to 80 ° C. and aging is carried out for 2 hours, and the outer surface of the first wall layer composed of an amino resin having a mercapto group is composed of an epoxy resin. A dispersion of microcapsules in which dimethyl silicone oil as a heat storage agent was encapsulated in the shell formed with the second wall layer was obtained.

  The obtained dispersion was cooled to 25 ° C., and coarse capsules were removed with a standard sieve having an opening of 53 μm. Next, the microcapsule dispersion was put into a 2 L beaker, and water was added to make the total volume 1,000 ml. The microcapsule was allowed to settle as it was, and the supernatant was discarded. This operation was repeated three times to wash the microcapsules.

  The particle diameter of the thus obtained microcapsules (15) was measured, and the volume average particle diameter was 43.5 μm. Moreover, it carried out similarly to Example 13, and evaluated solvent resistance (isopropanol tolerance) and heat resistance of the obtained microcapsule (15). The results are shown in Table 3.

  As is apparent from Table 3, the microcapsules of Examples 13 to 15 have a first wall layer made of an amino resin having a shell and a second wall layer made of an epoxy resin. Since the encapsulation temperature and time of the first wall layer and the second wall layer were appropriately adjusted, the value of loss on drying after 2 hours to 6 hours was very small, showing high heat resistance, and against isopropanol Shows high resistance and further improves solvent resistance.

  Thus, it can be seen that by appropriately adjusting the encapsulation temperature and time of the first wall layer and the second wall layer, a multilayer microcapsule having further improved solvent resistance in addition to high heat resistance can be obtained.

  The multilayer microcapsule of the present invention is excellent in the impermeability of the contents, and has high solvent resistance and high heat resistance in addition to high mechanical strength. Moreover, the production method of the present invention can easily produce such a multilayer microcapsule. Therefore, the multilayer microcapsule and the method for producing the same of the present invention can be used in various applications and products in which the multilayer microcapsule can be used / applied, for example, a microcapsule adhesive or pressure-sensitive adhesive, a microcapsule plasticizer, and a microcapsule cosmetic It makes a great contribution in fields related to microcapsule-type magnetic materials, microcapsule-type heat storage agents, and the like.

Claims (7)

  A multilayer microcapsule in which a hydrophobic content is encapsulated in a shell, wherein the shell is composed of an amino resin having a mercapto group and a second wall layer composed of an epoxy resin; A multilayer microcapsule having a multilayer structure containing   The multilayer microcapsule according to claim 1, wherein the second wall layer is made of a melamine-crosslinked epoxy resin.   Initial dispersion obtained by reacting formaldehyde with at least one selected from the group consisting of urea, thiourea, melamine, benzoguanamine, acetoguanamine and cyclohexylguanamine after dispersing the hydrophobic contents in an aqueous medium The first wall layer composed of an amino resin having a mercapto group is formed on the surface of the contents by performing a condensation reaction in the presence of a compound having a mercapto group and a carboxy group or a sulfo group. Then, after the microcapsules in which the contents are encapsulated in the first wall layer are dispersed in an aqueous medium, a compound having an epoxy group is added to the outer surface of the first wall layer. A method for producing a multilayer microcapsule, comprising forming a second wall layer made of an epoxy resin.   The manufacturing method of Claim 3 which makes a crosslinking agent react with the compound which has an epoxy group when forming the said 2nd wall layer.   5. The method according to claim 3, wherein an epoxy / melamine condensate is added in addition to the compound having an epoxy group when forming the second wall layer.   The manufacturing method of any one of Claims 3-5 using the polysaccharide whose content of a galactose unit and an arabinose unit is 10 mass% or more when disperse | distributing the said hydrophobic content to an aqueous medium.   The production method according to claim 6, wherein the polysaccharide is soybean polysaccharide and / or gati gum.