JP3149092B2 - Double-walled microcapsule and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

BACKGROUND OF THE INVENTION What is microencapsulation?
This refers to encapsulating fine particles or droplets in a wall film to form capsules having various useful properties. Frequently, unstable substances are converted into microcapsules, which are used for various purposes while maintaining their properties.

Conventionally, in the fields of recording / display materials, fragrances, adhesives, etc., microencapsulation by a phase separation (coacervation) method has been mainly performed. However, in recent years, since a method for producing microcapsules using an amino resin as a wall film using in situ polymerization has been proposed, the raw materials are inexpensive, the production process is simple and easy, and the obtained microcapsule capsules This method became mainstream due to the good strength. In the above method, by using a specific water-soluble polymer (system modifier), it is possible to smoothly form a wall film of the amino resin, and thereafter, improvement mainly on selection of the system modifier has been actively performed. I have. For example, JP-A-54-25277, JP-A-54-107881,
Methods disclosed in various publications such as JP-A-56-51238 are disclosed.

[0004] However, these conventional amino resin walls are susceptible to cracking due to their hard and brittle nature. Further, generation of the crack is promoted by heat, moisture, and the like. Therefore, conventional microcapsules having an amino resin as a wall film are inferior in heat resistance and moisture resistance, and have a drawback that inclusions are likely to ooze during storage.

JP-A-59-170857 discloses a first outer shell layer of a resin obtained as a result of addition and / or condensation reaction with formaldehyde, and an organic solution on the first outer shell layer. Discloses a microcapsule toner having a second polymer outer layer deposited by phase separation from the polymer. However, in performing encapsulation according to the description of the publication, formation of a first outer layer and second outer layer The formation of the second shell layer in the organic solvent is troublesome because the batch formation is required and the inclusion is partially extracted into the organic solvent at the time of encapsulation to form the second shell layer in the organic solvent. Characteristics may be impaired. In addition, there is a problem that the heat resistance and moisture resistance of the obtained microcapsules are not sufficient.

An object of the present invention is to provide a microcapsule having excellent heat resistance and moisture resistance.

[0007]

The present invention provides a microcapsule comprising a hydrophobic material as a core material and the core material covered by a double wall comprising a primary wall and a secondary wall. The secondary wall has one or more weights selected from (1) urea and formaldehyde, (2) monomeric methylol urea or its low molecular weight polymer, and (3) monomeric methylated methylol urea or its low molecular weight polymer. A secondary wall comprising a polyion complex of a cationic polyamide-epihalohydrin resin having a urea bond in a structural unit and polystyrenesulfonic acid and / or a salt thereof. Emulsifying and dispersing a hydrophobic substance in water using at least one selected from double-walled microcapsules and polystyrenesulfonic acid and its salts as emulsifiers After that, (1) urea and formaldehyde (2) monomeric methylol urea or a low molecular weight polymer thereof,
And (3) a polycondensation reaction of one or more selected from monomer-methylated methylol urea or a low molecular weight polymer thereof to form a primary wall film, and then a cation having a urea bond in a structural unit A double-walled microfilm, comprising adding a conductive polyamide-epihalohydrin resin, depositing a polyion complex with the emulsifier on the primary wall film, and then performing a thermosetting reaction to form a secondary wall film. A method for producing a capsule is provided.

According to the study of the present inventors, an amino resin is formed as a primary wall by an in situ polymerization method, and at least one selected from polystyrenesulfonic acid and a salt thereof and a structural unit are formed on the primary wall. It was found that double-walled microcapsules in which a secondary wall composed of a polyion complex with a cationic polyamide-epihalohydrin resin having a urea bond therein was formed by a coacervation method were extremely excellent in heat resistance and moisture resistance. Was issued.

The hydrophobic substance serving as the core material in the present invention may be any substance as long as it does not have a serious adverse effect on the properties of the microcapsule of the present invention, and is a liquid or solid at room temperature and substantially insoluble in water. Known microcapsule core materials and the like can be widely used. For example, olive oil, vegetable oil, toluene, xylene, cyclohexanone, methyl stearate,
Water-insoluble liquids such as chlorinated biphenyls, water-insoluble substances consisting of fusible solids such as naphthalene, lauric acid and myristyl alcohol; water-insoluble metal oxides; activated carbon;
Examples thereof include water-insoluble solids such as pigments, water-insoluble synthetic polymer substances, water and water-insoluble solids such as glass and minerals, fragrances, bactericidal compositions, fertilizers, and thermochromic compositions.

The amino resin wall as the primary wall of the double-walled microcapsule of the present invention is formed by a polycondensation reaction of one or more selected from the following (1) to (3).

(1) Urea and formaldehyde (2) Monomeric methylol urea or its low molecular weight polymer (3) Monomeric methylated methylol urea or its low molecular weight polymer When the urea and formaldehyde are used, the molar ratio of the latter to the former is about 1.0 to 4.0,
More preferably, it is good to be about 1.4 to 3.0.

As the monomeric methylol urea, specifically, monomethylol urea, dimethylol urea and the like can be used. As the monomer methylated methylol urea, methylated monomethylol urea, methylated dimethylol urea and the like can be used. These low molecular weight polymers can be used without particular limitation as long as they show water solubility. Specific examples of the low molecular weight polymer include “Be
Etle60, Beetle65 (trade names, manufactured by American Cyanamid Co., Ltd.) and the like.

In the present invention, the primary wall is formed so as to be about 0.1 to 20 parts by weight, more preferably about 0.2 to 15 parts by weight, based on 100 parts by weight of the core material. When the primary wall is less than 0.1 parts by weight with respect to the core material, the coating of the core material becomes insufficient, and the desired effect cannot be obtained even if the secondary wall is formed later. On the other hand, if it exceeds 20 parts by weight,
At the time of encapsulation, it is not preferable because it causes thickening and gelation of the system and aggregation of the capsules.

In the present invention, the secondary wall comprises a cationic polyamide having at least one selected from polystyrenesulfonic acid and a salt thereof and a urea bond in the structural unit.
It is formed by a thermosetting reaction of a polyion complex with an epihalohydrin resin.

The polystyrene sulfonic acid (or a salt thereof) serving as a secondary wall material can act as an emulsifier for emulsifying and dispersing a hydrophobic substance in water when forming the primary wall. The polystyrene sulfonic acid has a number average molecular weight of about 100,000 to 6,000,000, and more preferably 200,000 to 2,000,000.
It is preferable to use one of about one million. Examples of polystyrenesulfonic acid salts include alkali metal salts such as sodium and potassium salts.

The cationic polyamide-epihalohydrin resin having a urea bond in the structural unit is obtained by using a condensate of a polyalkylene polyamine and urea as a diamine component.
This can be obtained by subjecting the resulting polyamine polyurea polyamide resin to dehydration condensation with dicarboxylic acids and further reacting epihalohydrin in an aqueous solution,
For example, Japanese Patent Publication No. 44-19822, U.S. Pat.
It can be manufactured according to the conditions described in No. 2085 and the like. As an example of a preferable production method, for example, the following method can be mentioned.

First, a urea and a polyalkylene polyamine are subjected to a deammonification reaction at 160 to 200 ° C. for 2 to 4 hours under a nitrogen stream, and then a dibasic acid is added to the mixture to form a 160 to 200 ° C.
For 2 to 4 hours. After gradually cooling, epihalohydrin was added at about 50 ° C. to perform a halohydrination reaction, and then water was added to obtain a resin content of 20 to
By adjusting the pH to about 4.5 to 5.0 as an aqueous solution of about 40% and terminating the reaction, the intended cationic polyamide-epihalohydrin resin can be obtained.

The ratio between the polyalkylene polyamine and the urea in the cationic polyamide-epihalohydrin resin is preferably such that the molar ratio of the former to the latter is about 2: 0.5 to 2.0. The amount of the dicarboxylic acid used is 0.95 to 1.3 with respect to the total mole number of the polyalkylene polyamine and urea.
About twice the molar amount is appropriate. Epihalohydrin is used in an amount of 0.1 to 1 mol of amino group in the polyamide resin.
A range of 5 to 1.5 moles is preferred.

The molecular weight of the cationic polyamide-epihalohydrin resin is not particularly limited, and any resin exhibiting water solubility can be used. The preferred degree of polymerization of the resin is 3 to
It is about 20.

Preferred examples of the cationic polyamide-epihalohydrin resin include diethylene triamine as a polyalkylene polyamine, terephthalic acid as a dibasic acid,
Epichlorohydrin is used as epihalohydrin, and specific examples thereof include resins described in Example 1 of JP-B-44-19822. Also,
As commercially available resins, "Euramine P5600", "Euramine T1200" (both trade names, manufactured by Mitsui Toatsu Chemicals, Inc.) and the like can also be suitably used.

The above polystyrene sulfonic acid and / or
The ratio of the salt to the cationic polyamide-epihalohydrin resin is preferably about 10 to 1000 parts by weight, more preferably 20 to 50 parts by weight, based on 100 parts by weight of the former.
The amount is preferably about 0 parts by weight. When the use ratio is less than 10 parts by weight, phase separation does not occur and encapsulation cannot be performed.
On the other hand, if it exceeds 1,000 parts by weight, phase separation occurs too vigorously, causing thickening and gelling of the system and aggregation of capsules.

In the present invention, the secondary wall is provided on the primary wall in an amount of about 0.01 to 200 parts by weight, more preferably about 0.1 to 100 parts by weight, based on 100 parts by weight of the core material. Formed. If the amount is less than 0.01 part by weight, the wall formation becomes insufficient and the desired effect cannot be obtained.
If the amount exceeds 0 parts by weight, a large amount of ion complex is required, which results in undesirably thickening and gelling of the system.

The size of the double-walled capsule of the present invention is not particularly limited, and may be appropriately adjusted according to the purpose. Usually, a size of about 1 to 200 μm can be obtained.

The double-walled microcapsule of the present invention comprises: (1) urea and formaldehyde (2) monomeric methylol urea or a low molecular weight polymer thereof on the surface of a hydrophobic substance;
And (3) after subjecting one or more selected from monomer methylated methylol urea or its low molecular weight polymer to a polycondensation reaction to form a primary wall film, and then selecting from polystyrene sulfonic acid and a salt thereof. It can be obtained by subjecting a polyion complex of at least one of the above and a cationic polyamide-epihalohydrin resin having a urea bond in the structural unit to a thermosetting reaction.

The method for forming the primary wall is not particularly limited, and may be in accordance with the conditions of a known in situ polymerization method. For example, it can be obtained according to the method described in JP-A-53-84883. . As the emulsifier, the above-mentioned polystyrene sulfonic acid and / or a salt thereof can be used, but other various known emulsifiers may be used.

After the formation of the primary wall, in the solution in which the primary wall was formed, or in a new solution after being separated from the solution in which the primary wall was formed, the hydrophobic solution in which the primary wall was formed is formed. A secondary wall is formed in the conductive material. In order to form the secondary wall, the primary wall was formed in an aqueous solution containing about 0.1 to 30% by weight, preferably about 1 to 10% by weight of polystyrenesulfonic acid and / or a salt thereof. The hydrophobic substance is dispersed, and a cationic polyamide-epihalohydrin resin is added to the dispersion with stirring, and the polyion complex with polystyrenesulfonic acid and / or a salt thereof having an anionic charge in the system is formed in a fine droplet form. It may be separated and deposited on the primary wall, and a thermosetting reaction may be performed at a temperature of about 60 to 80 ° C. for about 2 to 6 hours. The amount of dispersion of the hydrophobic substance forming the primary wall is not particularly limited, but is about 5 to 150 parts by weight of the hydrophobic substance with respect to 100 parts by weight of the aqueous solution.
Preferably, it may be about 30 to 100 parts by weight.

In the present invention, the primary wall and the secondary wall can be formed continuously by the following method, and double-walled microcapsules can be easily manufactured.

First, polystyrenesulfonic acid and / or a salt thereof is added in an amount of about 0.1 to 30% by weight, preferably 1 to 30% by weight.
A hydrophobic substance serving as a core material is added to an aqueous solution containing about 10% by weight, and the mixture is stirred and emulsified so as to have an average particle size of about 1 to 50 μm, preferably about 2 to 20 μm. In this case, if the added amount of polystyrene sulfonic acid and / or its salt is too small, the emulsified state is deteriorated, and it is easy to obtain a capsule having a coarse particle size and low strength. On the other hand, if the added amount is too large, the system thickens and gels. It is not preferable because it causes chemical conversion. The amount of the hydrophobic substance added is 5 parts per 100 parts by weight of the aqueous solution.
About 150 parts by weight, preferably about 30 to 100 parts by weight. If the added amount of the hydrophobic substance is too small, the dispersion becomes a dispersion having a low capsule solid concentration, and the productivity is poor.In addition, the capsule is liable to cause agglomeration. It is not preferable because it causes chemical conversion.

Next, the primary wall material (at least one of the above (1) to (3)) is added while stirring is continued, and the pH of the solution is adjusted to about 2.0 to 5.0.
The mixture is heated to about 90 ° C., and a polycondensation reaction is performed for about 1 to 6 hours to form a primary wall of the amino resin. The amount of the primary wall material added to the aqueous solution can be in the range of about 2 to 100 parts by weight based on 100 parts by weight of the hydrophobic substance. The addition amount may be appropriately adjusted so that a predetermined amount of the primary wall is formed. If the amount of the primary wall material used is too small, the wall formation becomes insufficient and only capsules with low strength can be produced, and if the amount used is too large, the system thickens and gels, which is not preferable. When urea and formaldehyde are used as the primary wall material, it is preferable that the amount of urea is about 2 to 30 parts by weight based on 100 parts by weight of the core material.
More preferably, it is about 15 parts by weight. Further, when a monomer methylol urea, a monomer methylated methylol urea, a low molecular weight polymer thereof or the like is used as the primary wall material, the amount of the primary wall material with respect to 100 parts by weight of the core material is It is preferably about 3 to 50 parts by weight, and 6 to 3 parts by weight.
More preferably, it is about 0 parts by weight. Incidentally, the primary wall material can be added before emulsification. In addition, the above pH
The adjustment of, for example, sodium hydroxide, sodium carbonate,
It can be performed using acetic acid, hydrochloric acid, sulfuric acid or the like.

Next, a cationic polyamide-epihalohydrin resin is added to the microcapsule dispersion liquid as described above with stirring, and a polyion complex with polystyrenesulfonic acid having an anionic charge and / or a salt thereof in the system is added. Is deposited on the primary wall by phase separation in the form of fine droplets, and is subjected to a thermosetting reaction at a temperature of about 60 to 80 ° C. for about 2 to 6 hours to form a secondary wall.

In the present invention, after forming the secondary wall, it is cooled and the double-walled microcapsules obtained by a conventional method such as centrifugation, filtration, spray drying and the like are recovered. Thus, the double-walled microcapsules of the present invention having an average particle size of about 1 to 200 μm are obtained.

[0032]

According to the double-walled capsule of the present invention, the urea bond is present in the structural unit of the cationic polyamide-epihalohydrin resin as the secondary wall material, so that the affinity with the urea amino resin of the primary wall is obtained. The primary and secondary walls of the resulting microcapsules are formed in a uniform, seamless and tightly adhered state.

When polystyrenesulfonic acid and / or a salt thereof is used as an emulsifier, the primary wall can be easily formed, and a good capsule dispersion state can be maintained when the secondary wall is formed. And the polyion complex with the cationic polyamide-epihalohydrin resin undergoes a very smooth phase separation and deposits on the primary wall without causing agglomeration.

Further, according to the present invention, the formation of the primary wall and the secondary wall can be performed continuously, and the production of double-walled microcapsules can be performed easily.

The double-walled microcapsules of the present invention are extremely excellent in heat resistance and moisture resistance as compared with those of the conventional amino resin wall only, and the characteristics are the same as those of the amino resin wall alone. Retained and not damaged.

The present invention is particularly useful in the fields of recording / display materials, fragrances, adhesives and the like.

[0037]

The characteristics of the present invention will be further clarified by showing examples and comparative examples.

[0038]

Example 1 3 g of polystyrene sulfonic acid (number average molecular weight: 500,000) and 6 g of urea were added to 97 g of water and dissolved by heating at 60 ° C., and then 90 g of methyl stearate was added, so that the droplet diameter became about 5 μm. Until emulsified. PH of liquid
Was 2.0. Next, 1 g of a 20% aqueous sodium hydroxide solution was added to the emulsion to adjust the pH to 3.2, 15.6 g of a 37% aqueous formaldehyde solution was added, and a polycondensation reaction was carried out at 60 ° C. for 3 hours to give methyl stearate. A primary wall was formed on the surface of the emulsified droplet using a urea-formaldehyde resin.

Next, 50 g of water was added, and 12 g of a cationic polyamide-epichlorohydrin resin having a urea bond (resin obtained by the production method of Example 1 described in JP-B-44-198272, solid content: 30%) was added dropwise. Then, a polyion complex with polystyrenesulfonic acid was phase-separated and deposited on the primary wall, and a curing reaction was performed at 60 ° C. for 3 hours to form a secondary wall. Thereafter, the mixture was cooled to room temperature, diluted with water and centrifuged to take out microcapsules. The average particle size of the obtained double-walled microcapsules is 6
μm.

[0040]

Example 2 3 g of polystyrene sulfonic acid (number average molecular weight: 500,000) was added to 97 g of water, dissolved by heating at 60 ° C., and 90 g of methyl stearate was added.
The mixture was stirred and emulsified until it became about μm. 20% of this emulsion
Adjusted to pH 3.2 using aqueous sodium hydroxide solution,
Further, a solution prepared by dissolving 10 g of dimethylol urea in 90 g of water was added, and a polycondensation reaction was carried out at 60 ° C. for 3 hours to form a primary wall on the surface of the emulsified droplet of methyl stearate. Thereafter, a secondary wall was formed in the same manner as in Example 1 to obtain a double-walled microcapsule. The average particle size of the double-walled microcapsules was 6 μm.

[0041]

Example 3 3 g of polystyrene sulfonic acid (number average molecular weight: 500,000) was added to 97 g of water, and after heating and dissolving at 70 ° C., 90 g of methyl stearate was further added, followed by stirring until the droplet diameter became about 5 μm. Emulsified. This emulsion is
The pH is adjusted to 3.0 using a 0% aqueous sodium hydroxide solution, 20 g of “Beetle65” (manufactured by American Cyanamid Co., Inc., methylated methylol urea precondensate) is added, and a polycondensation reaction is performed at 70 ° C. for 4 hours. A primary wall was formed on the surface of the emulsified droplet of methyl stearate. Example 1 below
A secondary wall was formed in the same manner as described above to obtain a double-walled microcapsule. The average particle size of this double-walled microcapsule is
It was 7 μm.

[0042]

Example 4 After forming a primary wall in the same manner as in Example 1, 50 g of water was added, and "Euramine P5600" (a cationic polyamide polyurea manufactured by Mitsui Toatsu Chemicals, Inc.) was used.
12 g of epichlorohydrin resin (solid content: 25%) was added dropwise, and the polyion complex with polystyrenesulfonic acid was phase-separated and deposited on the primary wall.
A time curing reaction was performed to form a secondary wall. afterwards,
The double-walled microcapsules cooled to room temperature, diluted with water and centrifuged out had an average particle size of 6 μm.

[0043]

Fifth Embodiment In the fourth embodiment, "Euramine P560
Double-walled microcapsules were obtained in the same manner except that "Euramine T1200" (manufactured by Mitsui Toatsu Chemicals, cationic polyamide polyurea-epichlorohydrin resin, solid content 30%) was used instead of "0". The average particle size of the double-walled microcapsules was 6 μm.

[0044]

Example 6 3 g of polystyrene sulfonic acid (number average molecular weight: 500,000) and 6 g of urea were added to 97 g of water and dissolved by heating at 60 ° C., and then 90 g of methyl stearate was added, so that the droplet diameter became about 5 μm. Until emulsified. Then, the emulsion was adjusted to pH using a 20% aqueous sodium hydroxide solution.
Adjusted to 3.2, 37% aqueous formaldehyde solution 15.
6 g and 10 g of "Beetle 65" were added, and a polycondensation reaction was carried out at 70 ° C. for 4 hours to form a primary wall on the surface of the emulsion droplets of methyl stearate.

Next, 50 g of water was added, and “Euramine T12
The polyion complex with polystyrenesulfonic acid was phase-separated and deposited on the primary wall by dropping 00 g of 12 g, and a curing reaction was performed at 70 ° C. for 4 hours to form a secondary wall. After cooling, dilution with water and centrifugation, the microcapsules were taken out, and the average particle size of the obtained double-walled microcapsules was 8 μm.

[0046]

Comparative Example 1 In Example 1, a microcapsule having only the primary wall (average particle size: 5 μm) was produced.

[0047]

Comparative Example 2 480 g of 37% formalin and 240 g of urea
Was heated to 70 ° C. for 1 hour, and 1 liter of ion-exchanged water was added to obtain an aqueous urea-formaldehyde precondensate solution. 100 ml of this aqueous solution of the initial condensate was diluted to 3 liters with ion-exchanged water, and 10% citric acid was added to adjust the pH to 5.0. 1 kg of methyl stearate was stirred and dispersed therein until the average particle size became 8 μm. Next, 10% citric acid was added to the mixture to adjust the pH to 3.5 while stirring was continued.
Quenched to complete the encapsulation of the primary wall. The aqueous dispersion was filtered with a vacuum filter and left in a dryer at 50 ° C. for 24 hours to obtain a capsule whose primary wall was coated with a urea-formaldehyde resin. Obtained capsule 1
kg of styrene-dimethylaminoethyl methacrylate (polymerization ratio 90:10) and D
Dispersed in a solution consisting of 4 liters of MF. While continuing to stir with a homomixer, 1 liter of ion-exchanged water was added dropwise at a rate of 10 ml / sec, and styrene-dimethylaminoethyl methacrylate was phase-separated and precipitated on the primary wall as a secondary wall. The dispersion was filtered with a vacuum filter and dried with a dryer at 50 ° C. for 24 hours to obtain double-walled microcapsules.

[0048]

Comparative Example 3 Double-walled microcapsules were prepared in the same manner as in Example 1, except that 25 g of "Smileds Resin 613" (manufactured by Sumitomo Chemical Co., Ltd., methylated methylolmelamine precondensate) was used in place of urea and formaldehyde. I got

[0049]

Comparative Examples 4 and 5 In Example 1, 5 g of ethylene maleic anhydride copolymer was used instead of polystyrene sulfonic acid.
Double-walled microcapsules were obtained in the same manner except that (Comparative Example 4) or 5 g of carboxymethylcellulose (Comparative Example 5) was used. However, in any case, the phase separation of the polyion complex did not proceed smoothly during the formation of the secondary wall, and the precipitation was too intense and the aggregation of the capsules was large,
The resulting capsules were not seamless and uniform in secondary wall.

[0050]

COMPARATIVE EXAMPLE 6 A double-walled microcapsule was prepared in the same manner as in Example 1 except that 7 g of gum arabic was used instead of polystyrene sulfonic acid. And production was impossible.

[0051]

Comparative Example 7 A double-walled microcapsule was produced in the same manner as in Example 1 except that 4 g of polyvinyl alcohol was used instead of polystyrene sulfonic acid. Secondary walls could not be formed due to no phase separation.

[Durability test] Examples 1 to 6 and Comparative Example 1
The heat resistance and humidity resistance of the microcapsules obtained in Nos. To 5 were evaluated as follows. The results are shown in Table 1.

Heat resistance : 20 in an oven at a temperature of 160 ° C.
It was represented by the weight retention (%) of the microcapsules before and after standing for minutes.

Humidity resistance : Expressed as the weight retention (%) of the microcapsules before and after standing for 48 hours in an atmosphere at a temperature of 70 ° C. and a humidity of 90 ° C.

The larger the weight retention ratio, the smaller the loss due to the exudation of the core material, indicating that the durability of the microcapsules is superior.

[0056] Further, when the microcapsules after the above heat resistance and humidity resistance test were observed with a scanning electron microscope, those of Examples 1 to 6 according to the present invention showed no deformation or abnormality before and after the test. In the case of Comparative Examples 1 to 5, capsule breakage and cracking were conspicuous, and shrinkage and deformation of the capsule due to seepage of the core material were also observed.

[0057]

Example 7 In Example 1, a thermochromic material having the following composition was used in place of methyl stearate, and double-walled microcapsules were obtained in the same manner.

(Thermochromic material) Crystal violet lactone 2 g Bisphenol A 4 g Lauric acid 45 g Myristic acid 20 g Palmitic acid 25 g It was a good thermochromic material which was repeated.

[0059]

Example 8 A double-walled microcapsule was obtained in the same manner as in Example 1, except that a perfume having the following composition was used instead of methyl stearate.

(Fragrance) Rose fragrance essence 20 g Alkyl naphthalene 70 g The obtained microcapsules were remarkably stable against heat and humidity, and were able to retain fragrance for a long period of time.

Claims (4)

(57) [Claims] 1. A microcapsule comprising a hydrophobic substance as a core material and said core material covered with a double wall comprising a primary wall and a secondary wall, wherein the primary wall comprises (1) urea and Formaldehyde (2) monomeric methylol urea or its low molecular weight polymer,
And (3) an amino resin formed by one or more polycondensation reactions selected from monomeric methylated methylol urea or a low molecular weight polymer thereof, and the secondary wall forms a urea bond in the structural unit. A double-walled microcapsule comprising a polyion complex of a cationic polyamide-epihalohydrin resin and polystyrenesulfonic acid and / or a salt thereof. 2. The method according to claim 1, wherein the primary wall and the secondary wall are 0.1 to 20 parts by weight and 0.01 to 20 parts by weight, respectively, based on 100 parts by weight of the core material.
The double-walled microcapsule according to claim 1, wherein the amount is 200 parts by weight. 3. A method of emulsifying and dispersing a hydrophobic substance in water using at least one selected from polystyrenesulfonic acid and a salt thereof as an emulsifier, and (1) urea and formaldehyde (2) monomer on the surface of the hydrophobic substance. Methylol urea or its low molecular weight polymer,
And (3) a polycondensation reaction of one or more selected from monomer methylated methylol urea or a low molecular weight polymer thereof to form a primary wall, and then a cationic unit having a urea bond in the structural unit Manufacturing a double-walled microcapsule, comprising adding a polyamide-epihalohydrin resin, depositing a polyion complex with the emulsifier on the primary wall, and then performing a thermosetting reaction to form a secondary wall. Law. 4. The method according to claim 3, wherein the cationic polyamide-epihalohydrin resin is added in an amount of 10 to 1000 parts by weight based on 100 parts by weight of the emulsifier.