JP7066489B2 - Manufacturing method of microcapsules - Google Patents

Description

The present invention relates to a method for producing microcapsules, and more particularly to a method for producing microcapsules having carboxymethyl cellulose as a membrane wall.

Microcapsules can be manufactured by chemical methods such as condensation polymerization, physicochemical methods such as core selvation method, in-liquid drying method, melting dispersion cooling method, pan coating method, air suspension method, and spray drying. There are mechanical methods such as law.

The chemical method by the above condensation polymerization (hereinafter referred to as the condensation polymerization method) is, for example, as shown in Patent Document 1, a polyurethane resin or polyurea resin made from a polyfunctional isocyanate as a raw material, or a melamine made from a methylol melamine as a raw material. This is a method for manufacturing microcapsules having a resin or the like as a membrane wall. However, this method has a problem that carbon dioxide gas is generated in the formation of a polyurethane film wall or a polyurea film wall, and formaldehyde is generated in the formation of a melamine resin film wall.

In the composite core selvation method, a polycation solution and a polyanion solution are used in combination as a polymer solution, and when these are mixed, a concentrated colloidal layer generated by phase separation due to electrical interaction is encapsulated. It is used for a chemical film (Non-Patent Document 1). As a method for producing microcapsules using carboxymethyl cellulose and / or a sodium salt thereof as a membrane wall, a method in which gelatin is used in combination in this composite core selvation method is used. As polyanions other than carboxymethyl cellulose used for composite core selvation, polysaccharides such as gum arabic, sodium alginate, carrageenan, and agar are known.

In this composite core selvation method, gas is not generated as in the above condensation polymerization method, but the pH is adjusted to cause phase separation, and an organic solvent (formaldehyde or ethanol) is used to further cure the concentrated colloidal layer. Etc.), and then the pH needs to be readjusted, which makes the work complicated, and it is also necessary to consider problems such as residual organic solvent and environmental pollution.

On the other hand, in Patent Documents 2 and 3, as a microencapsulation method using celluloses and using neither an organic solvent nor gelatin, an incompatible aqueous solution of celluloses and an aqueous solution of a copolymer are mixed. However, a production method for producing microcapsules by adding sodium chloride, calcium chloride, magnesium chloride, or sodium sulfate as a separating agent is disclosed.

However, in these methods shown in Patent Documents 2 and 3, it is necessary to combine a specific cellulose with a specific copolymer in order to obtain stable microcapsules, and to obtain microcapsules using carboxymethyl cellulose. No specific method is disclosed.

To solve such a problem, in Patent Document 4, carboxymethyl cellulose or a sodium salt thereof is used, and strong microcapsules can be easily produced without generating gas as in the above condensation polymerization method and without using an organic solvent. The manufacturing method obtained in the above is disclosed.

In the examples of Patent Document 4, it is described that microcapsules using hinoki oil as a core substance and carboxymethyl cellulose or a sodium salt thereof as a membrane wall are produced, but types of core substances such as other fragrances and fats and oils are described. In some cases, when the microcapsules were dried, the membrane wall was torn, the fragrance was dissipated, the residual scent disappeared, and the oil and fat ooze out.

Japanese Unexamined Patent Publication No. 11-188257 Japanese Unexamined Patent Publication No. 2000-033259 Japanese Unexamined Patent Publication No. 2001-205575 Japanese Unexamined Patent Publication No. 2012-217960

"Microcapsules-its manufacturing method, properties, and applications", Sankyo Publishing, co-authored by Yasushi Kondo and Masumi Koishi, October 15, 1977, pp. 49-55.

The present invention has been made in view of the above, and microcapsules using carboxymethyl cellulose as a membrane wall, which has excellent storage stability under drying, can be easily produced without using an organic solvent, regardless of the type of core substance. It is an object of the present invention to provide a method for producing microcapsules.

The method for producing a microcapsule of the present invention comprises a step of preparing an aqueous solution by further mixing one or more kinds of carboxymethyl cellulose and / or a sodium salt thereof and another water-soluble polymer in order to solve the above-mentioned problems. A hydrophobic substance or a hydrophobic composition having a viscosity at 25 ° C. of 100 to 10000 mPa · s by a B-type viscosity meter, or a hydrophobic substance having a viscosity of 100 to 10000 mPa · s at 25 ° C. by a B-type viscosity meter is added to the above aqueous solution. A step of preparing an emulsified suspension by adding a mixture of a sex substance or a hydrophobic composition and a hydrophobic substance having a melting point of 25 to 80 ° C., and adding a divalent or higher metal salt to the emulsified suspension. The above-mentioned carboxymethyl cellulose and / or its sodium salt has a degree of etherification of 0.5 to 0.8, a PVI value of 0.5 or less, and a structural viscosity of 50 or more, including a step of adding. It shall be .

Further, the carboxymethyl cellulose and / or its sodium salt can have a viscosity of 2% by mass aqueous solution at 25 ° C. by a B-type viscometer of 1 to 1000 mPa · s.

The water-soluble polymer is one or a mixture of two or more selected from the group consisting of sodium formaldehyde condensate of naphthalene sulfonate, sodium formaldehyde condensate of alkyl naphthalene sulfonate, polyvinyl alcohol, polystyrene sulfonic acid, and salts thereof. Can be.

The divalent or higher metal salt can be one or a mixture of two or more selected from the group consisting of calcium salt, iron salt, silver salt, zinc salt, barium salt, aluminum salt and copper salt.

According to the production method of the present invention, microcapsules having carboxymethyl cellulose as a membrane wall, which has excellent storage stability even under drying, can be easily produced without using any organic solvent, regardless of the type of core substance. Is possible.

Carboxymethyl cellulose (hereinafter, may be referred to as CMC) and / or a sodium salt thereof (hereinafter, may be referred to as CMC-Na) used in the present invention have a degree of etherification of 0.5 to 0.8. Is preferable. If the degree of etherification is less than 0.5, the water solubility is insufficient, the liquid does not become uniform, and the particle size distribution of the microcapsules becomes uneven, and the performance may vary. Further, if the degree of etherification exceeds 0.8, the strength of the microcapsules may decrease.

Further, for CMC and / or CMC-Na, the viscosity of the 2% by mass aqueous solution measured at a rotor rotation speed of 60 rpm and 25 ° C. by a B-type viscometer is preferably 1 to 1000 mPa · s, preferably 1 to 100 mPa · s. It is more preferably s, and even more preferably 4 to 40 mPa · s. The higher the viscosity, the more gelation occurs during emulsification, which tends to make uniform emulsification difficult, and the obtained microcapsule water dispersion also has a high viscosity and poor fluidity. Therefore, it is practically disadvantageous. On the other hand, when the viscosity is low, the concentration of CMC in the aqueous solution can be increased, and thus the thickness of the CMC film wall can be increased.

The PVI value of CMC and / or CMC-Na is preferably 0.5 or less, and the structural viscosity is preferably 50 or more, more preferably 60 or more. When the PVI value is 0.5 or less and the structural viscosity is 50 or more, microcapsules having excellent storage stability under drying can be easily obtained.

In this specification, the degree of etherification, the PVI value, and the structural viscosity are numerical values defined and measured in Examples described later.

The method for producing such CMC and CMC-Na is not particularly limited, but after performing an alkali celluloseization reaction in which an alkali is reacted with cellulose, an etherifying agent is added to the obtained alkali cellulose to carry out the etherification reaction. It can be manufactured by.

Specifically, it is preferable to include the following (step 1) alkali celluloseization reaction step, (step 2) etherification reaction step, and (step 3) thickening step, and according to such a production method, the degree of etherification. , PVI value and structural viscosity are within the above preferable ranges, and CMC and CMC-Na can be easily obtained.

(Step 1) Alkaline Cellulose Reaction Step The alkali cellulose reaction step is in a hydrous organic solvent (total amount 100% by mass) containing 10% by mass or more and 15% by mass or less of an alkali metal hydroxide, and is a cellulose raw material glucose. The reaction can be carried out using an alkali metal hydroxide of 1.0 mol or more and 5.0 mol or less per unit, for example, the reaction is carried out at a liquid temperature of 25 ° C. or more and 45 ° C. or less for 50 minutes or more and 80 minutes or less. It can be carried out.

Examples of the alkali metal hydroxide include lithium hydroxide, sodium hydroxide, potassium hydroxide and the like, and any one or a combination of two or more can be used. When the amount of the alkali metal hydroxide added is 1.0 mol or more, CMC and CMC-Na having an etherification degree of 0.5 or more can be easily obtained. Furthermore, the crystallized region of the cellulosic raw material is sufficiently destroyed, and the carboxymethyl etherification reaction is likely to be promoted. On the other hand, when the amount of the alkali metal hydroxide added is 5 mol or less per 1 mol of glucose unit, the excess alkali metal salt is suppressed from decomposing the etherifying agent in the etherification reaction, and the etherifying agent is effectively used. The rate improves.

The water-containing organic solvent is a mixed solvent of a predetermined organic solvent and water. As the organic solvent, an organic solvent generally used for producing CMC and CMC-Na can be used. Although not particularly limited, specific examples thereof include alcohol solvents such as ethyl alcohol, methyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol and isobutyl alcohol, ketone solvents such as acetone, diethyl ketone and methyl ethyl ketone, dioxane and diethyl ether. And so on. These may be used alone or as a mixture of two or more. Of these, monohydric alcohols having 1 to 4 carbon atoms are preferable, and monohydric alcohols having 1 to 3 carbon atoms are more preferable because of their excellent compatibility with water.

The content ratio of water to 100 parts by mass of the organic solvent of the water-containing organic solvent is not particularly limited, but is preferably 20 parts by mass or more and 60 parts by mass or less.

(Step 2) Ethereization reaction step In the etherification reaction step, the etherification agent is added at a liquid temperature of 20 ° C. or higher and 40 ° C. or lower for 50 minutes or longer and 80 minutes or shorter, and the etherification reaction is carried out at 70 ° C. or higher and 100 ° C. or lower. It is preferable to carry out the reaction at the following liquid temperature for 30 minutes or more and 120 minutes or less.

Examples of the etherifying agent include monochloroacetic acid and the like.

The amount of the etherifying agent added is appropriately set according to the set degree of etherification of CMC and CMC-Na.

(Step 3) Thickening Step It is preferable to add hydrogen peroxide to carboxymethyl cellulose and / or a salt thereof after the etherification step in a reaction system having a pH of 7.0 or higher to reduce the thickening, and the thickening is particularly limited. However, it can be carried out at a liquid temperature of 40 ° C. or higher and 70 ° C. or lower for 30 minutes or longer and 60 minutes or lower.

The amount of hydrogen hydrogen added in the thickening step is preferably 0.1% by mass or more and 10% by mass or less with respect to the raw material carboxymethyl cellulose sodium salt.

The method for producing microcapsules of the present invention is obtained by neutralizing the excess alkali contained in CMC and CMC-Na after the thickening step with an acid, removing the hydrous organic solvent, washing and drying, and then pulverizing the mixture. CMC and CMC-Na that can be suitably used for can be produced.

The water-soluble polymer other than CMC and / or CMC-Na used in the present invention is not particularly limited and may be of natural origin or may be obtained by chemical synthesis. Examples include xanthan gum, gellan gum, polyglutamic acid, arabic gum, guar gum, locust bean gum, carrageenan, starch, chitosan, pectin, and derivatives thereof, as well as synthetic organic polymers such as polyethylene glycol, polyvinyl alcohol, and polyvinylpyrrolidone. , Polyacrylic acid, polyacrylamide, sodium naphthalene sulfonate or a formaldehyde condensate of sodium alkylnaphthalene sulfonate or a salt thereof, polystyrene sulfonic acid or a salt thereof and the like can be exemplified. In addition to CMC and CMC-Na, cellulose derivatives such as hydroxyethyl cellulose, hydroxypropylmethyl cellulose, hydroxypropyl cellulose, and ethyl cellulose can also be used. Among these, formaldehyde condensates of sodium naphthalene sulfonate or sodium alkylnaphthalene sulfonate, polyvinyl alcohol, polystyrene sulfonic acid, and salts thereof are preferable. One of these water-soluble polymers may be used alone, or two or more of them may be used in combination.

The molecular weight of these water-soluble polymers is preferably 30 to 1,000,000, more preferably 10,000 to 100,000 in terms of weight average molecular weight (Mw). If the molecular weight is too low, the CMC film wall is difficult to form, and if the molecular weight is too high, the emulsified state tends to be unstable.

Next, examples of the divalent or higher valent metal salt used in the present invention include calcium salt, iron salt, silver salt, zinc salt, barium salt, aluminum salt, copper salt and the like. Preferred specific examples include iron chloride, iron sulfate, aluminum sulfate, aluminum acetate, myoban, silver nitrate, calcium hydroxide, zinc sulfate, copper sulfate, barium sulfate and the like. These divalent or higher metal salts may be used alone or in combination of two or more.

In the present invention, by using these divalent or higher metal salts, microcapsules having excellent core substance retention and easy release control can be obtained. This is due to the ion exchange between these divalent or higher metal salts and the hydrogen or sodium ions of the carboxyl group of the CMC, resulting in cross-linking between the CMC molecules, which results in microcapsules due to the strong CMC wall. Is considered to be due to the formation of. As described above, carbon dioxide gas is generated when the microcapsules made of the polyurethane film wall or the polyurea film wall are manufactured by the conventional condensation polymerization method, and formaldehyde is generated when the microcapsules made of the melamine resin are produced. However, in the present invention, since such gas is not generated, it is not necessary to remove the gas or unreacted substances, and the microencapsulation can be completed in a short time.

The core substance used in the capsule of the present invention is a hydrophobic substance or a hydrophobic composition having a viscosity of 100 to 10000 mPa · s measured at a rotor rotation speed of 60 rpm and 25 ° C. using a B-type viscosity meter, or a B-type viscosity. A hydrophobic substance having a viscosity of 100 to 10000 mPa · s measured at a rotor rotation speed of 60 rpm and 25 ° C. or a mixture of a hydrophobic composition and a hydrophobic substance having a melting point of 25 to 80 ° C. is melt-mixed. There is no particular limitation (hereinafter, these are collectively referred to as "hydrophobic substances, etc."). Hydrophobic substances include fragrances (natural fragrances, synthetic fragrances, plant essential oils, etc.), pesticides, physiologically active substances, repellents, deodorants, coloring agents, etc. If the viscosity is not within the specified range, the viscosity is high. Alternatively, a hydrophobic composition adjusted to a viscosity within the above-mentioned predetermined range can be used by mixing with a liquid such as a low-viscosity hydrophobic substance or a non-volatile oil. Examples of the liquid used for such viscosity adjustment include vegetable oils and fats and the above-mentioned fragrances. Further, a hydrophobic substance or a hydrophobic composition having a viscosity of 100 to 10000 mPa · s measured at 25 ° C. and a hydrophobic substance having a melting point of 25 to 80 ° C. are melt-mixed, and the mixture is solid at 25 ° C. However, it is preferable that the viscosity measured by a B-type viscosity meter at a rotor rotation speed of 60 rpm and a melt-mixed temperature is 100 mPa · s or more. The term "solid" refers to a state without fluidity.

The method for producing a microcapsule of the present invention comprises (1) a step of mixing CMC and / or CMC-Na with one or more other water-soluble polymers to prepare an aqueous solution, and (2) 25 in this aqueous solution. A hydrophobic substance or hydrophobic composition having a viscosity at 100 to 10000 mPa · s at ° C, or a hydrophobic substance or hydrophobic composition having a viscosity measured at 25 ° C by a B-type viscometer at 100 to 10000 mPa · s. A step of preparing an emulsified suspension by adding a mixture of a hydrophobic substance having a melting point of 25 to 80 ° C. and a step of adding a metal salt having a valence of 2 or more to the emulsified suspension. At least include.

In the step (1) for preparing an aqueous solution of CMC or the like, the concentration of CMC and / or CMC-Na in the aqueous solution is preferably 0.1 to 10% by mass, more preferably 1 to 5% by mass. The concentration of the water-soluble polymer other than CMC and / or CMC-Na in this aqueous solution is preferably 0.1 to 10% by mass, more preferably 1 to 5% by mass. This aqueous solution can be prepared according to a known method, and may be heated up to about 60 ° C., if necessary, in order to facilitate dissolution in water. When heated to a temperature exceeding 60 ° C., the viscosity of the aqueous solution such as CMC becomes too low, and the particle size of the microcapsules may vary.

Next, in the step of adding a hydrophobic substance or the like to the aqueous solution to prepare an emulsified suspension, the concentration of the hydrophobic substance or the like is 0. It is preferable to adjust the content to 1 to 50% by mass. If the concentration is higher than 50% by mass, emulsification may be difficult or the viscosity of the microcapsule water dispersion may increase. On the other hand, if it is less than 0.1% by mass, the microcapsules can be prepared without any problem, but the concentration of the target core substance becomes too low, which is not realistic from the economical point of view. The emulsified suspension can be carried out by a known method using a homodisper or the like.

Further, in the step of adding a divalent or higher metal salt to the emulsified suspension, the concentration of the divalent or higher metal salt is preferably 0.0001 to 0.01% by mass in the aqueous dispersion which is the target product, and is 0. .001 to 0.005% by mass is more preferable. As the timing of adding the metal salt, it is preferable to add it after the emulsified state is stable. When it is visually confirmed that the obtained emulsified suspension is sufficiently uniform, the emulsified suspension operation is terminated.

After the completion of the emulsification suspension operation, it is preferable to ripen at about 18 to 80 ° C. for about 1 to 24 hours. By performing the aging in this way, the cross-linking proceeds sufficiently, so that the CMC film wall can be further strengthened.

According to the above-mentioned production method of the present invention, an aqueous dispersion (including slurry) in which microcapsules are stably dispersed in water can be obtained. The microcapsules obtained by the production method of the present invention are substantially spherical particles having an average particle size of usually 1 to 1000 μm, and the average particle size is appropriately selected depending on the intended use, and the stirring speed by a homodisper or the like at the time of emulsification is adjusted. It can be adjusted by doing so.

The obtained microcapsule water dispersion can be used as it is, or can be diluted with water or the like if necessary. For example, in the case of a microcapsule water dispersion containing a fragrance as a core substance, the microcapsules are attached to the cloth product by appropriately diluting it, applying it to the cloth product by a method such as spraying or dipping, and drying it. Therefore, it is possible to obtain a cloth product in which the fragrance is retained for a long period of time.

In the above-mentioned production method of the present invention, additives such as surfactants, preservatives, pH adjusters, thickeners and the like usually used in the method for producing microcapsules are used as long as the object of the invention is not deviated. , Can also be added to the above aqueous solution or emulsified suspension.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples. In the following examples, "%" means "mass%" unless otherwise specified. The viscosity of the hydrophobic substance and the like is the viscosity at a rotor rotation speed of 60 rpm and 25 ° C. by a B-type viscometer, and the viscosity of CMC-Na is 2 masses at a rotor rotation speed of 60 rpm and 25 ° C. by a B-type viscometer. % Indicates the viscosity of the aqueous solution.

[Manufacturing of sodium carboxymethyl cellulose salt]
[Manufacturing Example 1]
100 g of low-density pulp crushed by a household mixer was charged into a kneader-type reactor having a capacity of 3 L equipped with a twin-screw stirring blade. After dissolving 60 g of sodium hydroxide in 500 g of a hydrous organic solvent mixed with IPA: water at a mass ratio of 80:20, it is put into the above-mentioned reactor charged with pulp and stirred at 35 ° C. for 60 minutes to form alkaline cellulose. The reaction was carried out to obtain alkaline cellulose. Next, 55 g of monochloroacetic acid was dissolved in 33 g of the hydrous organic solvent, adjusted to 25 ° C., the alkaline cellulose was added over 60 minutes while maintaining the temperature at 35 ° C., and then the temperature was raised to 80 ° C. over 30 minutes to 80 ° C. The etherification reaction was carried out at ° C. for 60 minutes.

After the etherification reaction, 5 g of a 20% hydrogen peroxide aqueous solution was added, and a slimming reaction was carried out at 50 ° C. for 60 minutes. After the above reaction, the unreacted excess sodium hydroxide was neutralized with 50% by mass of acetic acid to adjust the pH to 6.5 to 7.5. The neutralized product in the form of a slurry was taken out from the reactor and IPA was removed by centrifugation to obtain a crude carboxymethyl cellulose sodium salt. The crude carboxymethyl cellulose sodium salt was washed with a 70 mass% aqueous methanol solution to remove by-products sodium chloride, sodium glycolate and sodium acetate. After repeating this washing operation twice, it was dried at 80 ° C. for 4 hours and pulverized to obtain a sodium carboxymethyl cellulose salt.

As a result of measuring various physical properties of the obtained carboxymethyl cellulose sodium salt by the measuring method described later, the degree of etherification was 0.75, the viscosity of the 2% by mass aqueous solution was 15 mPa · s, the PVI value was 0.42, and the structural viscosity was 64. Met.

[Manufacturing Example 2]
Production was carried out in the same manner as in Production Example 1 except that the amount of monochloroacetic acid charged and the amount of water-containing organic solvent for dissolving monochloroacetic acid were changed as shown in Table 1 below to obtain the sodium carboxymethyl cellulose salt of Production Example 2.

As a result of measuring various physical properties of the obtained sodium carboxymethyl cellulose salt by the above-mentioned measuring method, the degree of etherification was 0.66, the viscosity of the 2% by mass aqueous solution was 80 mPa · s, the PVI value was 0.46, and the structural viscosity was 70. there were.

[Measurement of physical properties of sodium carboxymethyl cellulose salt]
<Degree of etherification>
0.6 g of sodium carboxymethyl cellulose salt was dried at 105 ° C. for 4 hours. After weighing the mass of the dried product, it was wrapped in filter paper and incinerated in a magnetic crucible. The ash was transferred to a 500 ml beaker, 250 ml of water and 35 ml of a 0.05 mol / l sulfuric acid aqueous solution were added, and the mixture was boiled for 30 minutes. After cooling, excess acid was back titrated with a 0.1 mol / l potassium hydroxide aqueous solution. Phenolphthalein was used as an indicator. Using the measurement results, the degree of etherification was calculated from the following formula (1).

(Degree of etherification) = 162 × A / (10000-80A) ... (1)
A = (af-bf1) / weight of dried product (g)
A: Amount (ml) of 0.05 mol / l sulfuric acid aqueous solution consumed by the bound alkali in 1 g of the sample.
a: Amount of 0.05 mol / l sulfuric acid aqueous solution used (ml)
f: Titer of 0.05 mol / l sulfuric acid aqueous solution b: Drop determination of 0.1 mol / l potassium hydroxide aqueous solution (ml)
titer of f1: 0.1 mol / l potassium hydroxide aqueous solution

<Viscosity of 2% by mass aqueous solution>
Sodium carboxymethyl cellulose salt (about 4.4 g) was placed in a 300 ml Erlenmeyer flask with a stopper and weighed precisely. An amount of water calculated by the formula “Sample (g) × (99-water content (% by mass))” was added thereto, and the mixture was allowed to stand for 12 hours and mixed for another 5 minutes. Using the obtained solution, the viscosity at 25 ° C. was measured using a BM type viscometer (single cylindrical rotary viscometer) according to JIS Z8803. At that time, (a) the rotor rotation speed is measured at 60 rpm, and (b) when the measured value in (a) above is 8000 mPa · s or more, the rotor rotation speed is changed to 30 rpm for measurement, and (c). When the measured value in (b) above was 16000 mPa · s or more, the rotor rotation speed was changed to 12 rpm for measurement.

<PVI value>
An aqueous solution having a viscosity of 10000 ± 500 mPa · s was adjusted using a sodium carboxymethyl cellulose salt, stirred well, covered with a wrap, and left overnight in a 25 ° C. incubator. Next, it was taken out from the incubator and sufficiently stirred with a glass rod. Next, the viscosity was measured at a rotation speed of 2 rpm using a BH type viscometer and rotor No. 5 (η2). Next, the viscosity was measured at a rotation speed of 20 rpm (η20). From these measured values, the PVI value was calculated by the following formula (2). The closer the PVI value is to 1.0, the stronger the Newtonian property, and the closer it is to 0, the stronger the non-Newtonian property.
PVI * = η20 / η2 ... (2)
* Printing Viscosity Index (Printing Viscosity Index)

<Structural viscosity>
An aqueous solution having a viscosity of 10000 ± 500 mPa · s was adjusted using a sodium carboxymethyl cellulose salt, stirred well, covered with a wrap, and left overnight in a 25 ° C. incubator. Next, it was taken out from the incubator and the viscosity at 20 rpm was measured using a BH type viscometer and rotor No. 5 (ηM). Next, after stirring at 400 rpm for 10 minutes using a three-one motor, the viscosity at 20 rpm was measured using a BH type viscometer and rotor No. 5 (ηm). The structural viscosity was calculated by the following formula (3) using each measured viscosity.
Structural viscosity (%) = (ηM-ηm) / ηM ... (3)

<Manufacturing of microcapsules>
[Example 1]
Table 2 shows the CMC-Na and polyvinyl alcohol (trade name: Gosenol GL-05, manufactured by Nippon Synthetic Chemical Industry Co., Ltd., saponification degree 88%, 4% viscosity 5.0 mPa · s) obtained in Production Example 1 above. The mixture was dispersed in water at the described compounding ratio, heated to 80 ° C. and dissolved to obtain an aqueous solution.

After dissolution, 60 g of the above aqueous solution cooled to room temperature was placed in a 300 mL tall beaker, a hydrophobic substance (oil phase) mixed at the ratio shown in Table 2 was added, and a homodisper (blade diameter φ40 mm, stirring) was added. It was emulsified for 10 minutes at a rate of 1000 rpm). Five minutes after the start of emulsification, 5 g of an aqueous solution of calcium chloride prepared to 0.1% was added little by little. As for the viscosity of the hydrophobic substance or the like, the rotor rotation speed is 60 rpm using a BM type viscometer (single cylindrical rotational viscometer) in the same manner as the measurement of the viscosity of the 2% by mass aqueous solution of the sodium carboxymethyl cellulose salt. And measured.

After the completion of emulsification, the blades of the homodisper are changed to a Ikari-shaped stirring blade, and the mixture is aged by stirring at 200 rpm for 1 hour at room temperature to obtain a microcapsule water dispersion having the composition shown in Table 2 (slurry, hereinafter Similarly) was obtained.

[Examples 2 to 7, Comparative Examples 1 and 2]
An aqueous solution was prepared by the same method as in Example 1 except that the hydrophobic substances and the like (oil phase) of Example 1 and CMC-Na were changed to the formulations shown in Table 2, and then emulsified. After the emulsification is completed, the blades are changed to a Ikari-shaped stirring blade, further heated to 60 ° C., and stirred at that temperature for 1 hour for aging to obtain a microcapsule water dispersion having the composition shown in Table 2. rice field.

As the hydrophobic substance of Example 5, castor oil and stearic acid were heated to 80 ° C. and melt-mixed. According to the B-type viscometer, the viscosity at a rotor rotation speed of 60 rpm and 80 ° C. was 20 mPa · s, but it solidified when the temperature dropped to 25 ° C.

The average particle size of the microcapsules obtained in each of the above Examples and Comparative Examples was measured by a laser diffraction type particle size distribution measuring device (SALD-2200, manufactured by Shimadzu Corporation). The results are shown in Table 2.

As shown in Table 2, in each of Examples 1 to 7 and Comparative Examples 1 and 2, microcapsules having an average particle size of 20 μm or less were obtained.

<Drying evaluation>
Place one drop of the microcapsule water dispersion obtained above on the sample table of a scanning electron microscope (SEM), air dry, and then observe with a scanning electron microscope to confirm the presence or absence of cracks in the membrane wall of the microcapsules. bottom.

As shown in Table 2, from the comparison between Examples 1 to 7 and Comparative Examples 1 and 2, when a predetermined hydrophobic substance or the like was used as the core substance of the microcapsules, no dry cracking was observed. ..

The microcapsules obtained by the production method of the present invention can be used for sustaining and controlling the release of fragrances (natural fragrances, synthetic fragrances, plant essential oils, etc.), pesticides, bioactive substances, repellents, deodorants, colorants, etc. ..

Claims (4)

A step of preparing an aqueous solution by further mixing one or more kinds of carboxymethyl cellulose and / or a sodium salt thereof and other water-soluble polymers.
In the aqueous solution, a hydrophobic substance or a hydrophobic composition having a viscosity at 25 ° C. of 100 to 10000 mPa · s by a B-type viscosity meter, or a hydrophobic substance having a viscosity at 25 ° C. of 100 to 10000 mPa · s by a B-type viscosity meter is added. A step of preparing an emulsified suspension by adding a mixture of a sex substance or a hydrophobic composition and a hydrophobic substance having a melting point of 25 to 80 ° C.
Including the step of adding a divalent or higher metal salt to the emulsified suspension.
The carboxymethyl cellulose and / or the sodium salt thereof has a degree of etherification of 0.5 to 0.8, a PVI value of 0.5 or less, and a structural viscosity of 50 or more. Manufacturing method. The method for producing microcapsules according to claim 1, wherein the carboxymethyl cellulose and / or its sodium salt has a viscosity of a 2% by mass aqueous solution at 25 ° C. of 1 to 1000 mPa · s by a B-type viscometer. The water-soluble polymer is one or a mixture of two or more selected from the group consisting of sodium formaldehyde condensate of naphthalene sulfonate, sodium formaldehyde condensate of alkyl naphthalene sulfonate, polyvinyl alcohol, polystyrene sulfonic acid, and salts thereof. The method for producing a microcapsule according to claim 1 or 2 , wherein the microcapsule is produced. The divalent or higher metal salt is characterized by being one or a mixture of two or more selected from the group consisting of calcium salt, iron salt, silver salt, zinc salt, barium salt, aluminum salt and copper salt. , The method for producing a microcapsule according to any one of claims 1 to 3 .