JP2005246320A - Microcapsule and production method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a microcapsule provided with a shell material whose core material has excellent impermeability and having high mechanical strengths, and to provide a production method for the microcapsule. <P>SOLUTION: The microcapsule is prepared by incorporating the hydrophobic core material into the shell material, wherein the shell material essentially consists of a constituent originated from a specified compound (A) and a constituent originated from a specified compound (B). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a microcapsule and a method for producing the same.

A microcapsule in which a hydrophobic core material (for example, an oily liquid material) is encapsulated in a shell body (hereinafter also referred to as a capsule shell body) serving as a partition wall layer is well known, such as non-carbon paper. Its usefulness is recognized in various applications such as pressure-sensitive and heat-sensitive recording materials, various sheets such as pressure measurement films, control release agents as pharmaceuticals and agricultural chemicals, adhesives, foods, rust preventives, and temperature indicating materials. Yes.
In general, the capsule shell is desired to be able to stably hold the core material contained therein (particularly liquid material). However, since the thickness of the shell of the microcapsule is very thin, the core material becomes the shell. Bleed-out phenomena such as permeation, oozing out of the shell or leakage are problematic. The bleed-out causes problems such as peripheral contamination, deterioration of powder characteristics of the microcapsules, aggregation of the microcapsules, and deterioration or poorness of adhesion and adhesion of the microcapsules to the base material. On the other hand, control release agents used in the fields of pharmaceuticals, agricultural chemicals, and fragrances, on the contrary, actively utilize this phenomenon, but at the time of its use, after use, at the time of its preparation, storage and transportation. In the stage before use, such as time, there is a case where it is similarly a problem because it is necessary to maintain the inclusion state of the core substance at a certain level.

Conventionally, as a microcapsule capable of solving such a bleed-out problem, the capsule shell is a so-called amino resin (urea resin, obtained by reaction of urea, a compound of melamine or guanamine, and formaldehyde. There are known microcapsules made of melamine resin, guanamine-based resin) or a resin obtained by crosslinking these (for example, see Patent Documents 1 and 2). Since such a resin or cross-linked resin has a very dense structure, the capsule shell is extremely excellent in the impermeability of a liquid substance or the like as a core substance, and the contained core substance is sufficiently stable. Thus, a microcapsule that can be held is obtained.
Japanese Patent Publication No.46-30282 JP-A-5-154375

However, the capsule shell made of the amino resin is very brittle and has a problem that it is easily broken or damaged by a weak impact or pressure.
This problem is thought to be mainly due to the fact that the amino resin itself has generally brittle physical properties, but it cannot be said that. As described above, microcapsules are required to have a very thin capsule shell due to various applications and demands from technical fields (for example, flexibility and adhesion), and a sufficient machine as a compensation. This is because the desired strength cannot be obtained. That is, regarding the above problem, it is considered that the kind of the constituent material of the capsule shell and the characteristic (thickness) of the capsule shell are synergistic factors.

For example, in applications such as carbonless paper and pressure measurement films, there are those that ultimately break the capsule shell and cause the liquid substance that is the inclusion to flow out, and break it when it is not necessary. In order to prevent such a problem, it is necessary to give the capsule shell an appropriate mechanical strength, but the adjustment is not easy. Therefore, it is possible to easily improve and adjust the mechanical strength against external loads such as stirring and pressurization during its preparation, use in various applications, and after use, etc., even though it is a very thin capsule shell. Has always been a problem, and even better from the recent technical level, is required.
Therefore, the problem to be solved by the present invention is to provide a microcapsule including a shell having excellent core material impermeability and high mechanical strength, and a method for producing the same.

The present inventor has intensively studied to solve the above problems. Specifically, with regard to the capsule shell, trial-and-error and examination were repeated with respect to providing the mechanical properties of the above-mentioned amino resin, while additionally providing high mechanical strength. As a result, as a shell forming material, a compound (an initial condensation compound (B) described later) for obtaining the amino resin is used, and a specific compound (a compound (A) described later) is also used. The present inventors have found that the above problems can be solved at once if the derived component is a microcapsule obtained so as to be an essential component of the capsule shell.
Methods for obtaining microcapsules, that is, techniques for microencapsulating a hydrophobic core material include so-called interfacial deposition methods such as coacervation method (phase separation method), melting decomposition cooling method and powder bed method, Examples thereof include so-called interfacial reaction methods such as legal methods, in-situ methods, in-liquid cured coating (coating) methods (orifice methods), and interfacial reaction methods (inorganic chemical reaction methods). The coacervation method is preferable from the viewpoint that the strength and thickness of the shell can be easily controlled and that a plurality of shells can be formed.

  In this coacervation method, in general, a water-soluble surfactant (dispersant) is used to disperse the hydrophobic core substance in the aqueous medium, and the capsule medium is dispersed in the aqueous medium after the dispersion. A water-soluble compound as a raw material is added. The specific compound (compound (A) described later) is used as the water-soluble surfactant, and the amino resin is obtained as the water-soluble compound. If the compound (initial condensation compound (B) mentioned later) to be used is used, the component derived from the compound which obtains the said amino resin on the surface of a core substance, The component derived from the said specific compound, It has been found that a capsule shell comprising can be easily formed and the above-mentioned problems can be solved at once.

Based on the above findings, the present invention has been completed.
Therefore, the microcapsule according to the present invention is a microcapsule in which a hydrophobic core substance is encapsulated in a shell, and the shell has the following general formula:
R ¹ — (CH ₂ —CH ₂ —O—) _n —X—R ²
(However, R ¹ represents an aliphatic or aromatic hydrophobic group having 5 to 25 carbon atoms, and R ² represents a polymer group having a polyamine structure or polycarboxylic acid structure having a weight average molecular weight of 300 to 100,000. , N represents an integer of 3 to 85. X is derived from a group capable of reacting with at least one group selected from the group consisting of an amino group, an imino group and a carboxyl group, and represents a group formed after the reaction. Represented, but may or may not be present.)
An initial condensation obtained by reacting formaldehyde with a component derived from the compound (A) represented by the formula: at least one selected from the group consisting of urea, thiourea, melamine, benzoguanamine, acetoguanamine and cyclohexylguanamine The component derived from the compound (B) is an essential component.

The method for producing a microcapsule according to the present invention comprises dispersing the hydrophobic core substance in an aqueous medium containing a water-soluble surfactant and adding the water-soluble compound to the aqueous medium after the dispersion. In the method for producing a microcapsule in which a shell is formed on the surface of the water-soluble surfactant, the water-soluble surfactant has the following general formula:
R ¹ — (CH ₂ —CH ₂ —O—) _n —X—R ²
(However, R ¹ represents an aliphatic or aromatic hydrophobic group having 5 to 25 carbon atoms, and R ² represents a polymer group having a polyamine structure or polycarboxylic acid structure having a weight average molecular weight of 300 to 100,000. , N represents an integer of 3 to 85. X is derived from a group capable of reacting with at least one group selected from the group consisting of an amino group, an imino group and a carboxyl group, and represents a group formed after the reaction. Represented, but may or may not be present.)
Obtained by reacting formaldehyde with at least one selected from the group consisting of urea, thiourea, melamine, benzoguanamine, acetoguanamine and cyclohexylguanamine as the water-soluble compound. The initial condensation compound (B) is used.

  According to the present invention, a hydrophobic core material is encapsulated in a shell, and the shell is made of a core material to the same extent as a shell made of a so-called amino resin such as urea resin, melamine resin, or guanamine resin. A microcapsule having excellent impermeability and high mechanical strength can be easily provided, and a method for producing such a microcapsule can also be easily provided.

Hereinafter, although the microcapsule concerning this invention and its manufacturing method are demonstrated in detail, the range of this invention is not restrained by these description, In the range which does not impair the meaning of this invention except the following illustrations. Changes can be made as appropriate.
As described above, the microcapsule of the present invention is a microcapsule in which a hydrophobic core substance is encapsulated in a shell (capsule shell), and the capsule shell is derived from the compound (A) described above. It is important that the constituents to be produced and the constituents derived from the above-mentioned initial condensation compound (B) (hereinafter sometimes referred to as compound (B)) are essential constituents.
In obtaining the microcapsules of the present invention, any conventionally known methods and techniques may be adopted as long as they can produce microcapsules having a shell having the above-described characteristic configuration. However, the “method for producing the microcapsule of the present invention” described later is preferable in that it can be obtained more easily.

Below, the manufacturing method of the microcapsule of this invention is demonstrated in detail first, and the characteristic and various physical properties of the microcapsule of this invention are demonstrated continuously.
As described above, the method for producing the microcapsules of the present invention comprises dispersing a hydrophobic core substance in an aqueous medium containing a water-soluble surfactant and adding a water-soluble compound to the aqueous medium after the dispersion. In forming a shell on the surface of the core substance, it is important to use the compound (A) described above as the water-soluble surfactant and the compound (B) described above as the water-soluble compound. is there. That is, in the present invention, not only the compound (B) which is a water-soluble compound but also the compound (A) which is a water-soluble surfactant is a raw material compound for the capsule shell.

The production method of the present invention can be said to be a microcapsule production method classified as a so-called coacervation method (phase separation method).
Hereinafter, a general method for producing a microcapsule for carrying out the present invention will be described, and features of the production method of the present invention will be described in detail. In the practice of the present invention, techniques, conditions, and the like other than those shown below can be appropriately applied techniques, conditions, and the like that can be generally employed in the microcapsule manufacturing method using the coacervation method.
In the production method of the present invention, first, a hydrophobic core substance is dispersed in an aqueous medium containing a specific water-soluble surfactant.

The aqueous medium that can be used in the production method of the present invention is not limited. For example, water or a mixed liquid of a hydrophilic organic solvent and water can be used. In the case where a hydrophilic organic solvent and water are used in combination, the water content is preferably 95 to 70% by weight, more preferably 95 to 80% by weight.
Examples of the hydrophilic organic solvent include, but are not limited to, alcohols such as methanol, ethanol, isopropyl alcohol, n-propyl alcohol, and allyl alcohol; ethylene glycol, propylene glycol, butylene glycol, hexylene glycol, and pentanediol. Glycols such as hexanediol, heptanediol, dipropylene glycol; ketones such as acetone, methyl ethyl ketone, methyl propyl ketone; esters such as methyl formate, ethyl formate, methyl acetate, methyl acetoacetate; diethylene glycol monomethyl ether, diethylene glycol mono Ethyl ether, diethylene glycol dimethyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, Ethers such as propylene glycol monomethyl ether; and the like preferably. These may be used alone or in combination of two or more.

In the production method of the present invention, in addition to the water and the hydrophilic organic solvent described above, another solvent may be used in combination with the aqueous medium. 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 keronine. It is done. When the other solvent is used in combination, the amount used is preferably 30% by weight or less, more preferably 25% by weight or less, and still more preferably based on the above-described hydrophilic organic solvent or an aqueous medium composed of water. Is 20% by weight or less.
The hydrophobic core material that can be used in the production method of the present invention is not limited as long as it is substantially insoluble in water and does not interact with the capsule shell formed to the extent that it impairs its function. Aromatic hydrocarbons such as xylene, toluene, benzene, dodecylbenzene, hexylbenzene, phenylxylylethane and naphthenic hydrocarbons; aliphatic hydrocarbons such as cyclohexane, n-hexane, kerosene and paraffinic hydrocarbons And the like. These may be used alone or in combination of two or more as required.

  The amount in which the core substance is dispersed in the aqueous medium is not limited, but for example, it is preferably 5 to 70 parts by weight, more preferably 10 to 65 parts by weight with respect to 100 parts by weight of the aqueous medium. If the amount of dispersion of the core material is less than 5 parts by weight, the concentration may be low, so it may take a long time to form a capsule shell, and the target microcapsules may not be prepared. In particular, the core material is a liquid material Becomes a microcapsule having a wide particle size distribution, which may cause a reduction in production efficiency. On the other hand, when the amount exceeds 70 parts by weight, the core material particles may aggregate, and particularly when the core material is a liquid material, droplet fusion (unification) may occur, and an inverse suspension is formed. Microcapsules may not be manufactured.

In the production method of the present invention, the specific water-soluble surfactant is represented by the following general formula (1):
R ¹ — (CH ₂ —CH ₂ —O—) _n —X—R ² (1)
(However, R ¹ represents an aliphatic or aromatic hydrophobic group having 5 to 25 carbon atoms, and R ² represents a polymer group having a polyamine structure or polycarboxylic acid structure having a weight average molecular weight of 300 to 100,000. , N represents an integer of 3 to 85. X is derived from a group capable of reacting with at least one group selected from the group consisting of an amino group, an imino group and a carboxyl group, and represents a group formed after the bonding. Represented, but may or may not be present.)
It is important to use the compound (A) represented by: By using the compound (A), the above-described problems of the present invention can be easily solved.

In the general formula (1), R ¹ represents an aliphatic or aromatic hydrophobic group having 5 to 25 carbon atoms, and specifically includes a pentyl group, hexyl group, heptyl group, octyl group, decyl group. Group, dodecyl group, octadecyl group, behenyl group and other aliphatic hydrocarbon groups, phenyl group, benzyl group, tolyl group, xylyl group, biphenyl group, p-terphenyl group, indenyl group, naphthyl group and indenyl-naphthyl group An aromatic hydrocarbon group such as, but not limited to.
The hydrophobic group represented by R ¹ has 5 to 25 carbon atoms, preferably 5 to 18 carbon atoms. If the number of carbon atoms is less than 5, the compound (A) may not exhibit sufficient surface activity, and if it exceeds 25, the hydrophobicity becomes too high and the solubility of the compound (A) in water decreases. There is a risk.

In the general formula (1), “— (CH ₂ —CH ₂ —O—) _n ” is a polymer group having a polyether structure (polyethylene oxide structure), and the structural unit “CH ₂ —CH ₂ — Although it is important that the number n of “O—” is 3 to 85, the above n is preferably 5 to 60, more preferably 5 to 50. When n is less than 3, although depending on the balance with the hydrophobic group, the solubility in an aqueous medium may not be sufficiently exhibited and the water may become insoluble. When it exceeds 85, the solubility in an aqueous medium may be increased. It becomes too high and it is hard to precipitate as an insoluble substance, and there exists a possibility that the structural component derived from a compound (A) may not fully be contained in a shell. Further, from the viewpoint of the physical properties of the shell of the microcapsule to be obtained, if n is in the above preferred range, it is possible to impart moderate flexibility to the shell and thus improve the mechanical strength of the shell. it can.

In the general formula (1), X is derived from a group capable of reacting (binding reaction) with at least one group selected from the group consisting of an amino group, an imino group, and a carboxyl group, and the reaction (binding reaction). Although the group formed later is represented, it may or may not be present in the general formula (1). Here, the amino group, imino group and carboxyl group are specifically the amino group and imino group which can be present in a polymer having a polyamine structure, and the carboxyl group which can be present in a polymer having a polycarboxylic acid structure. As the group capable of reacting with at least one group selected from the group consisting of these groups, a group represented by X ² in the following general formula (3) can be exemplified. Specific examples of the group represented by X include “—CH ₂ —CH ₂ —S—” derived from a group represented by the following structural formula (b) and “—NH” derived from an isocyanate group. —CO— ”,“ —CO—NH—CH ₂ —CH ₂ — ”derived from an oxazoline group,“ —CH (OH) — ”derived from an aldehyde group,“ —CO— ”derived from a carboxyl group. ”,“ —NH— ”derived from an amino group,“ ═N— ”derived from an imino group, and the like.

In the general formula (1), R ² represents a polymer group having a polyamine structure or a polycarboxylic acid structure having a weight average molecular weight of 300 to 100,000, and the weight average molecular weight is preferably 300 to 50, 000. When the weight average molecular weight is less than 300, it is difficult to precipitate as an insoluble material, and it may take a long time to form a shell, and a capsule shell with high strength may not be obtained. If it exceeds, the viscosity of the entire reaction system suddenly increases, which may make stirring difficult.If forced stirring is performed, when the core material is a liquid material, it becomes difficult to control the droplet size. There is a risk of becoming too much.

  The polymer group having a polyamine structure is not limited, but a polymer group having a polyamine structure containing a primary amino group and / or a secondary amino group, such as polyethyleneimine, polyamine, polyetheramine, polyvinyl At least selected from the group consisting of amine, modified polyvinylamine, polyalkylamine, polyamide, polyamine epichlorohydrin, polydialkylaminoalkyl vinyl ether, polydialkylaminoalkyl (meth) acrylate, polyallylamine, polyethyleneimine grafted polyamidoamine and protonated polyamidoamine Examples thereof include a polymer group having one type of structure.

The polymer group having a polycarboxylic acid structure is not limited, but acrylic acid, methacrylic acid, α-hydroxyacrylic acid, crotonic acid, phthalic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, aconitic acid and Examples thereof include a polymer group having a structure of a water-soluble polycarboxylic acid obtained by polymerization of a monomer component containing 30 mol% or more of an unsaturated carboxylic acid such as vinyl acetate.
The method for preparing the compound (A) represented by the above general formula (1) is not limited. For example, the following general formula (2) or the following general formula ( The method obtained by dripping the compound represented by 3) and making it react is preferable.

^{_{R 1 - (CH 2 -CH 2}} -O-) n-1 -X 1 (2)
(However, ^{X 1} is represented by the following structural formula (a):

Represents a group represented by )
R ¹ — (CH ₂ —CH ₂ —O—) _n —X ² (3)
(Where X ² is the following structural formula (b):

Or any one selected from the group consisting of an isocyanate group, an oxazoline group, an aldehyde group, a carboxyl group, an amino group and an imino group. That is, X ² represents a group capable of reacting (binding reaction) with at least one group selected from the group consisting of an amino group, an imino group, and a carboxyl group. )
When the compound represented by the general formula (2) is used in the preparation of the compound (A), the group represented by X does not exist in the general formula (1). On the other hand, when the compound represented by the general formula (3) is used, a group represented by X is present in the general formula (1).

Although it does not limit as reaction temperature at the time of making it react, when using polyamine, 10-90 ° C is preferred, more preferably it is 15-80 ° C, and when using polycarboxylic acid, it is 20-20. 100 degreeC is preferable, More preferably, it is 20-90 degreeC. Moreover, although reaction time is not limited, 0.5 to 5 hours are preferable, More preferably, it is 1 to 5 hours.
In the production method of the present invention, the compound (A) used as the water-soluble surfactant may be dissolved in the aqueous medium before the hydrophobic core substance is dispersed in the aqueous medium. It may be dissolved simultaneously with or after being dispersed, and is not limited.

  In the production method of the present invention, the compounding ratio of the compound (A) is preferably 1 to 30% by weight, more preferably 3 to 25% by weight, and still more preferably, with respect to the hydrophobic core substance. 5 to 25% by weight. If the compounding ratio of the compound (A) is less than 1% by weight, the dispersion state of the hydrophobic core substance cannot be maintained sufficiently stably, and the core substance particles may aggregate, particularly the core substance. In the case where is a liquid substance, there is a possibility that the droplets coalesce (unify). On the other hand, if it exceeds 30% by weight, the viscosity of the entire reaction system may increase rapidly, and stirring may become difficult. Control is difficult and may be too small. Further, from the viewpoint of the physical properties of the shell of the obtained microcapsule, if the compounding ratio of the compound (A) is within the above preferable range, the shell can be imparted with appropriate flexibility, and thus the shell mechanical Strength can be improved.

In the production method of the present invention, together with the compound (A), other compounds can be used as long as the effects of the present invention are not hindered. Examples of the other water-soluble surfactants include polyvinyl alcohols, various surfactants, natural polymer dispersants such as gelatin and gum arabic, and synthetic polymers such as styrene / maleic acid copolymers and salts thereof. A dispersant, and the like.
In the production method of the present invention, the method for dispersing the hydrophobic core substance in the aqueous medium is not limited, but a generally known dispersion method may be employed. In particular, when the core substance is a liquid substance, for example, a mixture containing an aqueous medium, a hydrophobic core substance, and a water-soluble surfactant is mixed with a disper, a homomixer (manufactured by Tokugi Kikai Kogyo Co., Ltd.) and a homogenizer (Nippon Seiki). The above mixture is dispersed in a static tube mixer (Noritake Static Mixer (manufactured by Noritake Company Limited)), Sulzer Mixer (Sumitomo Heavy Industries). Kogyo Co., Ltd.), Sakea mixer (manufactured by Sakura Seisakusho Co., Ltd.), TK / ROSS / LPD mixer (made by Special Machinery Co., Ltd.) and the like; In an aqueous medium containing a hydrophobic core substance, such as SPG membrane (Shirasu porous glass) and microchannel emulsification device (Eptec Co., Ltd.) were regulated. Method of passed disperse; and the like preferably.

In the production method of the present invention, a shell is formed on the surface of the hydrophobic core material by adding a specific water-soluble compound to the aqueous medium after the hydrophobic core material is dispersed.
The specific water-soluble compound is obtained by reacting at least one selected from the group consisting of urea, thiourea, melamine, benzoguanamine, acetoguanamine and cyclohexylguanamine (hereinafter referred to as an amino compound) with formaldehyde and initial condensation. It is important to use compound (B). The initial condensation compound (B) is a compound that is a precursor of a so-called amino resin (urea resin, melamine resin, guanamine resin). By using the compound (B) as a specific water-soluble compound, a shell having an amino resin as an essential constituent can be formed. By using the compound (B) in combination with the compound (A) described above, A shell comprising a component derived from the compound (A) in the resulting amino resin can be formed, and the above-described problems of the present invention can be easily solved.

  When the compound (B) is obtained by reacting at least one of urea and thiourea (hereinafter referred to as urea-based compound) with formaldehyde, the component of the urea-based resin (Ii) when it is obtained by reacting melamine and formaldehyde, it becomes an initial condensation compound that can be a constituent of the melamine resin, and (iii) from benzoguanamine, acetoguanamine and cyclohexylguanamine. When it is obtained by reacting at least one selected from the following group (hereinafter referred to as guanamine-based compound) with formaldehyde, it is an initial condensation compound that can be a constituent component of the guanamine-based resin. In the case of (iv) one obtained by reacting two or more of urea compounds, melamines and guanamine compounds with formaldehyde, two of urea resins, melamine resins and guanamine resins are used. It becomes an initial condensation compound that can be a constituent component of a resin in which species or more are mixed. As said compound (B), any 1 type in these initial condensation compounds may be used, 2 or more types may be used together, and it is not limited.

  In the reaction of the amino compound to obtain the compound (B) and formaldehyde, water is generally used as a solvent. Therefore, as a reaction form, formaldehyde can be generated by adding an amino compound to an aqueous solution (formalin) and reacting, or by adding trioxane or paraformaldehyde to water. The method of adding an amino compound to an aqueous solution and reacting it is preferred, and among them, the former method is more preferable in terms of economy, such as the need for a preparation tank for an aqueous formaldehyde solution and the availability. . Moreover, the said reaction form should just be a form with which an amino compound and formaldehyde react in a mixed state, For example, in the form which adds the aqueous solution of formaldehyde to an amino compound other than the form which adds an amino compound to the aqueous solution of formaldehyde There may be. In addition, it is preferable to perform the said reaction under stirring with a well-known stirring apparatus etc.

Among the amino compounds, urea compounds, melamine, co-condensates of urea compounds and melamine, and co-condensates of melamine and guanamine compounds are preferable, and urea compounds and melamine are more preferable. And a cocondensate of a urea compound and a melamine compound, more preferably a melamine and a cocondensate of a urea compound and a melamine.
In addition to the amino compounds listed above, other amino compounds may be used as the amino compound as the starting compound of the compound (B). For example, capriguanamine, amelin, amelide, ethylene urea, propylene urea, and acetylene Examples include urea. When these other amino compounds are also used, these other amino compounds are also treated as amino compounds that serve as raw material compounds for the compound (B).

  In the reaction for obtaining the compound (B), the molar ratio of amino compound to formaldehyde and formaldehyde “amino compound (mol) / formaldehyde (mol)” is not limited, but is 1 / 0.5 to 1/10. The ratio is preferably 1/1 to 1/8, more preferably 1/1 to 1/6. If the molar ratio is less than 1/10, the amount of unreacted formaldehyde may increase, and if it exceeds 1 / 0.5, the amount of unreacted amino compound may increase. When the above reaction is carried out using water as a solvent, the amount of amino compound and formaldehyde added to water, that is, the concentration of the amino compound and formaldehyde at the time of charging is higher as long as the reaction is not hindered. It is desirable to be.

  The compound (B) is not limited, but is preferably an initial condensation compound having a water miscibility (an index of the degree of polycondensation rate) of 100 to 5000%, more preferably 200 to 3000%. The water miscibility here refers to the water required to produce white turbidity when 5 g of an initial condensation compound obtained by the reaction of an amino compound and formaldehyde is sampled and water is added dropwise while maintaining at 15 ° C. This is a value obtained by multiplying the weight ratio of the weight and the initial condensation compound “water (g) / initial condensation compound (g)” by 100. If the water miscibility exceeds 5000%, the hydrophilicity is great, the shell form takes a long time, and the productivity may be inferior. If it is less than 100%, it has appropriate flexibility and mechanical properties. There is a possibility that a shell with high strength cannot be obtained. Further, the degree of polycondensation rate of the compound (B) can be managed by GPC (gel permeation chromatography), LC (liquid chromatography), etc. in addition to the water miscibility, and from the viewpoint of operability and reproducibility among others. Management by water miscibility is preferred.

The reaction temperature at the time of the reaction of the amino compound and formaldehyde to obtain the compound (B) is as follows. Based on the water miscibility described above, the progress of the reaction is grasped over time and immediately, and the desired reaction end point (target point) is accurately determined. It is preferable that the temperature is in the range of 65 to 75 ° C. so that the reaction can be completed by an operation such as cooling the reaction liquid when the desired reaction end point is recognized. Thereby, the reaction liquid containing the said compound (B) is obtained. The reaction time is not limited and can be set as appropriate.
The above compound (B) is usually suitable for organic solvents such as acetone, dioxane, methyl alcohol, ethyl alcohol, isopropyl alcohol, butyl alcohol, ethyl acetate, butyl acetate, methyl cellosolve, ethyl cellosolve, methyl ethyl ketone, toluene and xylene. Although soluble, it is substantially insoluble in water.

  The amount of the compound (B) added is not limited, but is preferably 0.1 to 10 parts by weight, more preferably 0.5 to 5 parts by weight, based on 1 part by weight of the compound (A). More preferably, it is 0.5-3 weight part. The thickness of the capsule shell formed can be easily controlled by adjusting the amount of compound (B) added. If the amount of the compound (B) added is less than 0.1 parts by weight, a sufficient amount and sufficient thickness of the capsule shell may not be formed. There is a risk that the composition is greatly biased and the shell strength is lowered. In addition, from the viewpoint of the physical properties of the shell of the microcapsule obtained, the mechanical strength and bleedout prevention are prevented because the thickness of the compound (B) added is less than 0.1 parts by weight. There is a possibility that the shell will have a low performance, and if it exceeds 10 parts by weight, the shell may have a low mechanical strength due to poor flexibility.

The method for adding the compound (B) to the aqueous medium is not limited, and may be batch addition or sequential addition (continuous addition and / or intermittent addition).
In the production method of the present invention, a capsule shell comprising the compound (A) in an insoluble reactant (amino resin) derived from the compound (B) may be formed on the surface of the hydrophobic core substance. it can. Thus, although the mechanism by which the shell is formed in the form of compound (A) being contained in the amino resin is not clear, shell formation using the compound (B) by the coacervation method (microencapsulation) ) In the presence of the compound (A), it is considered that the capsule shell as described above can be easily formed.

In the production method of the present invention, the temperature at which the capsule shell is formed (the temperature of the aqueous medium in which the hydrophobic core material is dispersed and the water-soluble compound is added) is not limited, but is preferably 25 ° C to 85 ° C, more Preferably it is 30 to 70 degreeC, More preferably, it is 35 to 60 degreeC.
An aging period may be further provided after the shell is formed. The temperature at the time of aging is not limited, but is preferably the same as the reaction temperature, and the aging time is not limited, but is preferably 1 to 5 hours, more preferably 1 to 3 hours.
In the production method of the present invention, a preparation liquid containing microcapsules and an aqueous medium is obtained by the above-described shell formation and aging as necessary.

  In the production method of the present invention, if necessary, the compound (A) may be further added to the microcapsule preparation solution, and the compound (B) may be added. By doing so, a similar shell can be further formed on the previously formed capsule shell, and as a result, a microcapsule having a shell formed of a plurality of layers is obtained. A microcapsule in which a shell composed of a plurality of layers is formed, for example, can further improve the physical properties obtained in a single-layer shell, and the inner layer and the outer layer of the capsule shell, Different physical properties can be expressed by changing the composition of the constituent components. Specifically, there is an effect that physical properties such as adhesiveness, high hydrophilicity, and flexibility can be easily introduced while having the original performance of the capsule shell.

In the production method of the present invention, an epoxy compound (compound having an epoxy group) is further added to the microcapsule preparation liquid after the shell formation comprising a single layer or a plurality of layers as described above, A layer made of an epoxy compound can be formed on the surface of the shell. By doing so, it is possible to obtain a shell body that is more flexible and has a high opportunity strength.
The epoxy compound is not limited, but a water-soluble epoxy compound having two or more epoxy groups in one molecule is preferable. For example, sorbitol polyglycidyl ester, solovitane polyglycidyl ester, (poly) glycerol polyglycidyl ester , Pentaerythritol polyglycidyl ester, triglycidyl tris (2-hydroxyethyl) isocyanurate, trimethylolpropane polyglycidyl ester, neopentyl glycol diglycidyl ester, ethylene, polyethylene glycol diglycidyl ester, propylene, polypropylene glycol diglycidyl ester and azide Pick acid diglycidyl ester and the like can be preferably used. These may be used alone or in combination of two or more.

  The epoxy compound has a water solubility of preferably 50% by weight or more, more preferably 60% by weight or more, still more preferably 70% by weight or more, and particularly preferably 100% by weight. When the dissolution rate satisfies the above range, the epoxy compound layer can be uniformly and rapidly formed, and excellent effects such as easy control of the thickness of the epoxy compound layer can be obtained. In addition, suppose that the solubility with respect to the water of an epoxy compound is a value calculated | required with the following measuring methods. Specifically, 25.0 g of a sample compound (epoxy compound) was precisely weighed into a 300 mL beaker, 225 g of water was added, and the sample compound was dissolved by stirring vigorously with a magnetic stirrer for 1 hour, and then allowed to stand for 1 hour. The undissolved sample compound (oil) precipitated at the bottom of the beaker is withdrawn, placed in a 10 mL (or 5 mL) graduated cylinder, and allowed to stand for another 30 minutes, and then the liquid volume (mL) of the sample compound (oil) is reduced. Read up to the first decimal place and substitute the value into the following formula to calculate the dissolution rate (%) of the sample compound (epoxy compound) in water.

Dissolution rate in water (%) = 100− (A / 21) × 100
(However, A represents the liquid volume (mL) of the read sample compound.)
The epoxy compound preferably has a weight average molecular weight of 300 to 10,000, more preferably 300 to 8,000, and still more preferably 300 to 5,000. When the weight average molecular weight satisfies the above range, excellent effects such as easy thickness of the epoxy compound layer can be obtained. When the weight average molecular weight is less than 300, it is difficult to obtain the effect of improving flexibility due to the formation of the epoxy compound layer, and it may be difficult to form a uniform epoxy compound layer. On the other hand, if it exceeds 10,000, the viscosity of the entire microcapsule preparation solution will increase rapidly, and stirring during the formation of the epoxy compound layer may be difficult. If forced stirring is performed, the microcapsules will be destroyed or damaged. There is a risk of

The amount of the epoxy compound added is not limited, but is preferably 0.5 to 10 parts by weight, more preferably 0.5 to 5 parts by weight, and still more preferably 0. 5 to 3 parts by weight. By adjusting the addition amount of the epoxy compound, the thickness of the formed epoxy compound layer can be easily controlled. If the amount added is less than 0.5 parts by weight, the effect of improving the flexibility due to the formation of the epoxy compound layer may not be obtained, and even if it exceeds 10 parts by weight, there is no particular problem. There is a risk that the improvement in effects such as mechanical strength and flexibility commensurate with the above will not be recognized, resulting in poor economic efficiency.
The temperature at which the epoxy compound layer is formed is preferably the same as the temperature at which the capsule shell is formed.

When forming the said epoxy compound layer, a crosslinking agent can be added besides an epoxy compound. By further adding and using a crosslinking agent, the strength of the epoxy compound layer to be formed, and thus the strength of the capsule shell can be further increased, and the shell can be destroyed in the subsequent microcapsule isolation and washing steps. It is possible to effectively suppress damage. The timing of addition of the crosslinking agent is not limited and may be added together with the epoxy compound or may be added before or after the addition of the epoxy compound, but is preferably added after the addition of the epoxy compound.
Examples of the crosslinking agent include, but are not limited to, sodium diethyldithiocarbamate (including hydrate), diethylammonium diethyldithiocarbamate (including hydrate), dithiosuccinic acid, and dithiocarbonate. These may be used alone or in combination of two or more. Moreover, although the usage-amount of the said crosslinking agent is not limited, For example, it is preferable to set it as 1-100 weight part with respect to 100 weight part of epoxy compounds, More preferably, it is 5-80 weight part, More preferably, it is 10 ~ 80 parts by weight. If the amount of the crosslinking agent used is less than 1 part by weight, it may be difficult to control the thickness of the epoxy compound layer, and if it exceeds 100 parts by weight, the reaction with the epoxy group in the epoxy compound becomes excessive. There is a possibility that an epoxy compound layer rich in flexibility cannot be formed.

In the production method of the present invention, microcapsules may be isolated as needed after preparing the microcapsules by a microencapsulation step. For example, after the microcapsules are prepared, the microcapsules can be separated and isolated from the aqueous medium by suction filtration or natural filtration.
After the isolation, the microcapsules may be classified to obtain microcapsules with a sharper particle size distribution.
For the classification, for example, a wet classification method (wet classification) is preferably adopted. Wet classification is a method of classifying microcapsules with respect to a prepared solution obtained by microencapsulation. Since classification is performed on the prepared solution, wet classification is performed. Specifically, the above preparation solution is classified as it is or diluted with an arbitrary aqueous medium or the like, and the microcapsules in the preparation solution are classified so as to have a desired particle size and particle size distribution. The wet classification can be performed by, for example, a method or an apparatus using a method such as a sieve type (filter type), a centrifugal sedimentation type, or a natural sedimentation type. For microcapsules having a relatively large particle size, the sieve type can be used effectively.

It is also preferable to perform an operation of washing the obtained microcapsules in order to remove impurities and improve product quality.
Hereinafter, characteristics and various physical properties of the microcapsule of the present invention will be described.
Regarding the details of the hydrophobic core substance, the compound (A) and the compound (B) in the microcapsule of the present invention, the description in the production method of the present invention can be similarly applied.
The form of the component derived from the compound (A), which is an essential component of the shell in the microcapsule of the present invention, may be composed of one molecule of the compound (A), dimer or 3 It may be a collection of two or more molecules such as a monomer, and is not limited. Of these, only one kind may be contained in the shell, or two or more kinds may be contained in the shell.

Although the content rate of the structural component derived from the said compound (A) is not limited, It is preferable that it is 10 to 80 weight% with respect to the whole shell, More preferably, it is 15 to 70 weight%, More preferably, it is 20 ~ 60% by weight. If the content is less than 10% by weight, the shell may not be sufficiently flexible and may have a low mechanical strength. If it exceeds 80% by weight, the bleed-out preventing ability is insufficient. There is a risk of becoming.
Similarly, various amino resins (urea-based resin, melamine resin, guanamine-based resin) can be used as the form of the component derived from the compound (B), which is an essential component of the shell in the microcapsule of the present invention. . Only 1 type of these may be contained in the shell, and 2 or more types may be contained in the shell.

Although the content rate of the structural component derived from a compound (B) is not limited, It is preferable that it is 20 to 90 weight% with respect to the whole shell, More preferably, it is 30 to 85 weight%, More preferably, it is 40 to 80% by weight. If the content is less than 20% by weight, the bleed-out preventing ability may be insufficient, and if it exceeds 90% by weight, the shell may have poor flexibility and low mechanical strength. is there.
Further, the composition ratio “compound (A) / compound (B) (weight ratio)” between the component derived from the compound (A) and the component derived from the compound (B) is not limited. / 90 to 80/20, preferably 15/85 to 70/30, and more preferably 20/80 to 60/40. If the molar ratio is less than 10/90, sufficient flexibility may not be obtained, resulting in a shell having low mechanical strength. If the molar ratio exceeds 80/20, bleeding out prevention ability is sufficient. There is a risk of becoming a non-shell.

As a component of the shell in the microcapsule of the present invention, other components other than the essential components described above may be included as long as the above-described effects of the present invention are not impaired, and are not limited. Examples of the other constituent components include constituent components derived from the above-described other compounds that can be used in combination with the compound (A). Specifically, constituent components derived from polyvinyl alcohols, various surface activity Constituents derived from agents, constituents derived from natural polymer dispersants such as gelatin and gum arabic, constituents derived from synthetic polymer dispersants such as styrene / maleic acid copolymers and their salts, etc. Can be mentioned.
The microcapsule of the present invention is a microcapsule comprising a capsule shell having high mechanical strength. The strength of the microcapsule of the present invention (the strength of the capsule shell) is not limited, but it is preferable that the mechanical strength of the microcapsule measured by the method described in Examples below is 50 g or more. More preferably, it is 100 g or more, More preferably, it is 200 g or more. If the mechanical strength is less than 50 g, the effects of the present invention described above may not be obtained.

The shape of the microcapsule of the present invention is not limited, but is preferably in the form of particles such as a true sphere or an oval sphere.
Although the particle diameter (volume average particle diameter) of the microcapsule of the present invention is not 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 microcapsule is less than 5 μm, there is a possibility that the microcapsule does not encapsulate the core substance. If it exceeds 500 μm, the physical properties normally required as a microcapsule cannot be maintained, or the microcapsule It may be difficult to control the strength of the glass.

The coefficient of variation of the particle size (volume average particle size) of the microcapsules of the present invention is preferably 30% or less, more preferably 25% or less, and even more preferably 20% or less. If the coefficient of variation exceeds 30%, the abundance of those having effective particle diameters as microcapsules is lowered, and there is a possibility that a large number of microcapsules need to be used.
The particle size of the microcapsules of the present invention and the coefficient of variation thereof (that is, the sharpness of the particle size distribution) are dispersed in an aqueous medium in the production process when, for example, a liquid material (such as an oily liquid) is used as the core material. This greatly depends on the particle size and particle size distribution of the droplets. Therefore, microcapsules having a desired particle diameter and a coefficient of variation thereof can be obtained by appropriately adjusting the dispersion conditions of the droplets.

Although the thickness of the shell of the microcapsule of the present invention is not limited, it is preferably 0.5 to 10 μm in a wet state, more preferably 1 to 10 μm, still more preferably 2 to 10 μm. If the thickness of the shell is less than 0.5 μm, sufficient strength as the shell may not be obtained. If the thickness exceeds 10 μm, there is no particular problem, but the core per unit weight of the microcapsule The weight of the substance will be reduced, which is not preferable.
The microcapsules of the present invention can be preferably used for various applications and products such as capsule-type adhesives, capsule-type cosmetics, microcapsule-type magnetic materials, and microcapsule-type heat storage materials, but are not limited thereto.

Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to these. Hereinafter, for the sake of convenience, “liter” may be simply referred to as “L”. In addition, “wt%” may be described as “wt%”.
Measurement methods in Examples and Comparative Examples are shown below.
<Particle size of microcapsule>
The volume average particle size of the microcapsules was measured using a laser diffraction / scattering particle size distribution measuring device (product name: LA-910, manufactured by Horiba, Ltd.).
<Thickness of shell (shell layer) of microcapsule>
From the microcapsule dispersion, 10 microcapsules having a particle diameter of about 50 μm are arbitrarily selected and taken out, and the thickness of each capsule shell (shell layer) is measured using a microscope (product name: power high scope KH-2700, (Made by Hyrocks Co., Ltd.) and the magnification was 2500 times. These average values were taken as the thickness of the capsule shell (shell layer) of the obtained microcapsules.

<Mechanical strength of microcapsules (mechanical strength of shell)>
The microcapsule was filtered from the microcapsule dispersion to obtain a microcapsule paste. This paste was weighed so that 10 g of the solid content derived from the microcapsules was contained, and 10 g of a binder having a solid content concentration of 10 wt% (acrylic water-soluble binder, film forming temperature 2 ° C.) was added to the paste. Water was added so that the solid content concentration was 40 wt% to form a paint. This paint was applied to a PET film having a thickness of 250 μm using an applicator (clearance: 150 μm), air-dried for 30 minutes, and then dried at 100 ° C. for 10 minutes to obtain a sheet coated with microcapsules.

Next, using a pencil hardness meter (manufactured by Yasuda Seiki Seisakusho Co., Ltd.), the above sheet was placed on white plain paper with the coated surface of the microcapsules down. Then, from the PET film side, observe the degree of color contamination of white plain paper in blue when the load is 50g, 100g, 200g, 300g using a 7H pencil, and determine the mechanical strength of the microcapsules. Evaluation was made according to the following criteria.
◎: No dyeing ○: Slightly dyed △: Slightly dyed x: Dyeing in a state of large bleeding <Weight reduction ratio when heating microcapsules>
The microcapsules were filtered from the microcapsule dispersion to obtain a microcapsule paste, and the weight (weight a) after the paste was once dried by a hot air dryer at 50 ° C. was measured. Then, it heat-dried at 110 degreeC for 2 hours, and also heat-dried at the same temperature for 2 hours. ^First , the weight (weight b ¹ ) after heat drying for 2 hours and the weight (weight b ² ) after further heat drying for 2 hours (that is, after heat drying for 4 hours) were measured. The weight reduction rate (wt%) was determined by the following formula.

Weight reduction rate (%) = [{weight a− (weight b ¹ or weight b ² )} / weight a] × 100
In actual use of the microcapsules, the shell body is used after being sufficiently dried by heating, or is often used continuously under heating conditions. Since the core material undergoes temperature expansion, the shell having low strength (mechanical strength) is damaged or destroyed. In particular, when a liquid material is used as the core material, bleed out is promoted by the internal pressure increase due to the damage or expansion of the core material, and the liquid material leaks and evaporates. It will be greatly reduced compared to before. The mechanical strength of the microcapsule (the mechanical strength of the shell) and the ability to prevent bleed-out can be objectively evaluated by the magnitude of the weight reduction rate.

[Synthesis Example 1-1]
A 300 mL separable flask was initially charged with 14.5 g of polyethyleneimine (product name: Epomin SP006 (Mw = 600), manufactured by Nippon Shokubai Co., Ltd.) and 43.5 g of water, and then prepared in advance under stirring. 97.2 g of a 25 wt% aqueous solution of the epoxy compound (lauryl polyoxyethylene (n = 22) glycidyl ester, water solubility: 100%) was added dropwise over 10 minutes.
After dropping while keeping the liquid temperature at 25 ° C. or lower at the time of dropping, stirring was continued for 30 minutes, and then the temperature was raised to 70 ° C., kept at the same temperature for 2 hours, then cooled to room temperature, and dispersion performance was improved. A compound (A1) having a solid content concentration of 25 wt% was obtained.

[Synthesis Example 1-2]
In Synthesis Example 1-1, 24 g of polyethyleneimine (product name: Epomin SP006 (Mw = 600), manufactured by Nippon Shokubai Co., Ltd.) and 72 g of water were initially charged, and then prepared in advance under stirring. Solid content concentration having dispersibility in the same manner as in Synthesis Example 1-1 except that 96 g of a 25 wt% aqueous solution of the compound (lauryl polyoxyethylene (n = 10) glycidyl ester, water solubility: 80%) was dropped. 25 wt% of compound (A2) was obtained.
[Synthesis Example 1-3]
In a flask similar to Synthesis Example 1-1, 93.7 g of polyacrylic acid (product name: Aquaric HL-415 (Mw = 10,000, 45 wt% aqueous solution), manufactured by Nippon Shokubai Co., Ltd.) and 281.1 g of water Then, under stirring, 20 g of a 25 wt% aqueous solution of an epoxy compound (phenol polyoxyethylene (n = 5) glycidyl ester, solubility in water: 100%) prepared in advance over 10 minutes is stirred. It was dripped.

After dropping while keeping the liquid temperature at 25 ° C. or lower at the time of dropping, stirring was continued for 30 minutes, and then the temperature was raised to 70 ° C., kept at the same temperature for 2 hours, then cooled to room temperature, A compound (A3) having a solid content concentration of 25 wt% was obtained.
[Synthesis Example 1-4]
In Synthesis Example 1-1, 83.7 g of polyethyleneimine (Mw = 180,000) and 334.8 g of water were initially charged, and then the epoxy compound (seryl polyoxyethylene (n = 88) Except that 15 g of 20 wt% aqueous solution of glycidyl ester, water solubility: 80%) was dropped, a compound (A4) having a solid content concentration of 20 wt% having dispersibility was obtained in the same manner as in Synthesis Example 1-1. Obtained.

[Synthesis Example 2-1]
A 100 mL round bottom separable flask was charged with 5 g of melamine, 5 g of urea, 20 g of a 37 wt% aqueous formaldehyde solution and 1 g of 25 wt% aqueous ammonia, and the temperature was raised to 70 ° C. while stirring. The whole became transparent at around 65 ° C. during the temperature increase.
After raising the temperature to 70 ° C. and holding at the same temperature for 1 hour, the mixture was cooled to 30 ° C. to obtain Compound (B1) which is an initial condensation compound of melamine, urea and formaldehyde.
[Synthesis Example 2-2]
A flask similar to Synthesis Example 2-1 was charged with 10 g of melamine, 20 g of a 37 wt% aqueous formaldehyde solution, and 1 g of 25 wt% aqueous ammonia, and the temperature was raised to 60 ° C. while stirring. The whole became transparent during the heating.

After raising the temperature to 60 ° C. and holding at that temperature for 15 minutes, the mixture was cooled to 30 ° C. to obtain a compound (B2) which is an initial condensation compound of melamine and formaldehyde.
[Synthesis Example 2-3]
A flask similar to Synthesis Example 2-1 was charged with 8 g of melamine, 2 g of benzoguanamine, 20 g of a 37 wt% aqueous formaldehyde solution and 2 g of 25 wt% aqueous ammonia, and the temperature was raised to 75 ° C. with stirring. After confirming that the whole became transparent when the temperature reached 75 ° C., it was immediately cooled to 30 ° C. to obtain Compound (B3), which is an initial condensation compound of melamine, benzoguanamine and formaldehyde.

[Example 1]
A 500 mL flat bottom separable flask is charged with 40 g of compound (A1) and 60 g of water, and stirred with a disper (product name: ROBOMICS, manufactured by Tokushu Kika Kogyo Co., Ltd.) with 94 g of alkylnaphthalene prepared in advance as an azo system. 100 g of a blue hydrophobic liquid in which 6 g of the blue oil dye was dissolved was added, and then the stirring speed was gradually increased, followed by stirring at 800 rpm for 5 minutes to obtain a suspension.
Under stirring, the whole amount of the compound (B1) was added to the suspension, the temperature was raised to 35 ° C., and the mixture was kept at the same temperature for 2 hours to form a shell layer as a capsule shell.

Next, the temperature was raised to 70 ° C. over 60 minutes, and kept at the same temperature for 2 hours for aging.
After aging, the mixture was cooled to room temperature to obtain a dispersion of microcapsules (1).
About the obtained microcapsule (1), the particle diameter, the thickness of the shell layer, the mechanical strength, and the weight reduction rate during heating were measured and evaluated by the method described above. These results are shown in Tables 1 and 2.
[Example 2]
In Example 1, except that Compound (A2) was used in place of Compound (A1) and Compound (B2) was used in place of Compound (B1), Microcapsule (2) A dispersion of was obtained.

The obtained microcapsules (2) were measured and evaluated in the same manner as in Example 1 and the results are shown in Tables 1 and 2.
Example 3
In Example 1, except that Compound (A3) was used instead of Compound (A1) and Compound (B3) was used instead of Compound (B1), Microcapsule (3) A dispersion of was obtained.
The obtained microcapsules (3) were measured and evaluated in the same manner as in Example 1, and the results are shown in Tables 1 and 2.

Example 4
A 500 mL flat bottom separable flask was charged with 40 g of compound (A4) and 60 g of water, and stirred with a disper (product name: ROBOMICS, manufactured by Tokushu Kika Kogyo Co., Ltd.) with 94 g of an alkylnaphthalene prepared in advance. 100 g of a blue hydrophobic liquid in which 6 g of the blue oil dye was dissolved was added, and then the stirring speed was gradually increased, followed by stirring at 800 rpm for 5 minutes to obtain a suspension.
Under stirring, the whole amount of the compound (B1) was added to the suspension, the temperature was raised to 35 ° C., and the mixture was kept at the same temperature for 2 hours to form a shell layer as a capsule shell.

Further, while maintaining the same temperature, 20 g of compound (A1) was added to the contents of the flask, and then polyglycerol polyglycidyl ester as an epoxy compound (manufactured by Nagase Chemtech Co., Ltd., product name: Denacol EX521, weight) (Average molecular weight: 732, solubility in water: 100%) An aqueous solution in which 10 g was dissolved in 50 g of water was added dropwise for 10 minutes, and then an aqueous solution in which 2 g of sodium diethyldithiocarbamate trihydrate was dissolved in 100 g of water was added for 10 minutes. It was dripped. The same temperature was maintained for 2 hours to form a second shell layer.
Further, the temperature was raised to 70 ° C. over 60 minutes, and the same temperature was maintained for 2 hours for aging.
After aging, the mixture was cooled to room temperature to obtain a dispersion of microcapsules (4).

The obtained microcapsules (4) were measured and evaluated in the same manner as in Example 1, and the results are shown in Tables 1 and 2. Further, when observed with a microscope (product name: Power Hiscope KH-2700, manufactured by Hilox Co., Ltd.) at a magnification of 2500, the microcapsule (4) has two shell layers as capsule shells. It was confirmed that it was formed.
[Comparative Example 1]
5 g of styrene / maleic acid copolymer (raw material monomer composition ratio: styrene (mol) / maleic acid (mol) = 1/1, weight average molecular weight (Mw): 20,000) was dissolved in 100 g of 1 wt% NaOH aqueous solution. Solution (C) was prepared.

Solution (C) is charged into a 500 mL flat bottom separable flask, and stirred with a disper (product name: ROBOMICS, manufactured by Tokushu Kika Kogyo Co., Ltd.) with 94 g of an alkylnaphthalene prepared in advance, an azo blue oil dye 100 g of blue hydrophobic liquid in which 6 g was dissolved was added, and then the stirring speed was gradually increased, followed by stirring at 800 rpm for 5 minutes to obtain a suspension.
Under stirring, the whole amount of the compound (B1) was added to the suspension, the temperature was raised to 35 ° C., and the mixture was kept at the same temperature for 2 hours to form a shell layer as a capsule shell.
Next, the temperature was raised to 70 ° C. over 60 minutes, and kept at the same temperature for 2 hours for aging.
After aging, the mixture was cooled to room temperature to obtain a dispersion of microcapsules (c1).

  The obtained microcapsules (c1) were measured and evaluated in the same manner as in Example 1 and the results are shown in Tables 1 and 2.

The microcapsules of the present invention are, for example, various pressure-sensitive or heat-sensitive recording materials such as non-carbon paper, various sheets such as pressure measurement films, control release agents as pharmaceuticals and agricultural chemicals, adhesives, foods, cosmetics, magnetic materials It can be suitably used for various applications and products such as heat storage materials, rust inhibitors and temperature indicating materials.
The production method according to the present invention is suitable for producing the microcapsules of the present invention.

Claims (5)

A microcapsule in which a hydrophobic core substance is encapsulated in a shell,
The shell body has the following general formula:
R ¹ — (CH ₂ —CH ₂ —O—) _n —X—R ²
(However, R ¹ represents an aliphatic or aromatic hydrophobic group having 5 to 25 carbon atoms, and R ² represents a polymer group having a polyamine structure or polycarboxylic acid structure having a weight average molecular weight of 300 to 100,000. , N represents an integer of 3 to 85. X is derived from a group capable of reacting with at least one group selected from the group consisting of an amino group, an imino group and a carboxyl group, and represents a group formed after the reaction. Represented, but may or may not be present.)
A component derived from the compound (A) represented by:
An essential component comprising at least one selected from the group consisting of urea, thiourea, melamine, benzoguanamine, acetoguanamine and cyclohexylguanamine and a component derived from the initial condensation compound (B) obtained by reacting formaldehyde As an ingredient,
A microcapsule characterized by that. A microcapsule for forming a shell on the surface of a core material by dispersing a hydrophobic core material in an aqueous medium containing a water-soluble surfactant and adding a water-soluble compound to the aqueous medium after the dispersion. In the manufacturing method,
As the water-soluble surfactant, the following general formula:
R ¹ — (CH ₂ —CH ₂ —O—) _n —X—R ²
(However, R ¹ represents an aliphatic or aromatic hydrophobic group having 5 to 25 carbon atoms, and R ² represents a polymer group having a polyamine structure or polycarboxylic acid structure having a weight average molecular weight of 300 to 100,000. , N represents an integer of 3 to 85. X is derived from a group capable of reacting with at least one group selected from the group consisting of an amino group, an imino group and a carboxyl group, and represents a group formed after the reaction. Represented, but may or may not be present.)
And using the compound (A) represented by
As the water-soluble compound, an initial condensation compound (B) obtained by reacting at least one selected from the group consisting of urea, thiourea, melamine, benzoguanamine, acetoguanamine and cyclohexylguanamine with formaldehyde is used.
A method for producing a microcapsule characterized by the above.   The manufacturing method of the microcapsule of Claim 2 which adds 0.1-10 weight part of said initial condensation compounds (B) with respect to 1 weight part of said compounds (A).   The manufacturing method of the microcapsule of Claim 2 or 3 whose compounding ratio of the said compound (A) with respect to the said core substance is 5 to 50 weight%.   The method for producing a microcapsule according to any one of claims 2 to 4, wherein a crosslinking agent is further added to the aqueous medium after dispersion.