JP2739587B2 - Method for producing thermoreversible discolorable microcapsules - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing thermoreversible color-changing microcapsules.

2. Description of the Related Art Microcapsules are currently used in various fields such as pharmaceuticals, cosmetics, livestock feed, food and drink, and dyes.
In particular, microcapsules that reversibly change color at a specific temperature are prepared, for example, as printing inks or paints, applied to paper, cloth, or the like, or mixed into synthetic resin molded products, resulting in an impression. Used for the purpose of displaying temperature.

Examples of the method for producing microcapsules include a coacervation method, an interfacial polymerization method, an in situ polymerization method, and a spray drying method. Above all, the in situ polymerization method is a preferable method because it provides a capsule having a robust wall film and excellent water resistance and microbial resistance.

The following are proposed microcapsules produced by the in situ polymerization method: * A hydrophobic substance is dispersed in an aqueous solution containing an ethylene-maleic anhydride copolymer and urea, and formalin is added thereto. , A microcapsule obtained by forming a urea / formalin polymer (Japanese Patent Publication No. 54-16949) * Ethylene / maleic anhydride copolymer, propylene /
A hydrophobic substance is emulsified in an aqueous solution of a copolymer such as a maleic anhydride copolymer, and melamine and formalin,
Microcapsules obtained by adding a wall material such as monomeric methylol / melamine and polymerizing the wall material
No. 59-35258) * A hydrophobic substance is dispersed or emulsified in an acidic aqueous solution of a maleic anhydride copolymer such as a styrene / maleic anhydride copolymer or an isobutylene / maleic anhydride copolymer. Microcapsules obtained by adding melamine / formalin resin by adding formalin initial shrinkage (Japanese Patent Publication No. 60-2100) * Disperse or emulsify a hydrophobic substance in an acidic aqueous solution of styrene / maleic anhydride copolymer After that, microcapsules obtained by adding urea, resorcin and formalin to form a urea / formalin polymer (JP-A-54-53679) * Partial ethylene glycol monoalkyl of styrene / maleic anhydride copolymer After dispersing or emulsifying a hydrophobic substance in an acidic aqueous solution of an ether ester, melamine / formalin Condensate was added, the melamine / formaldehyde polymer microcapsules obtained by forming (JP 60-216839) * oil-soluble vinyl monomer (isobutylene, styrene,
A hydrophobic substance is dispersed or emulsified in an acidic aqueous solution of a water-soluble resin obtained by adding a water-soluble vinyl monomer to a terpolymer of vinyl acetate / maleic anhydride / maleic ester and polymerizing the terpolymer. Microcapsules obtained by adding a precursor of an amino resin (amino compound (melamine, urea, etc.) / Formalin polymer, polymer of methylol compound of amino compound, etc.) and polymerizing the mixture (Japanese Patent Application Laid-Open No.
However, the microcapsules have the following disadvantages. That is, the capsule disclosed in Japanese Patent Publication No. 54-16949 may be colored depending on the type of the leuco dye contained in the capsule.
Not preferred. The capsule disclosed in JP-B-59-35258 cannot obtain a sufficient coloration. Also, Japanese Patent Publication No. 60-2100
The microcapsules disclosed in JP-A-54-53679, JP-A-60-216839 and JP-A-61-25635 have poor emulsification stability of an emulsion of a hydrophobic substance, and have very high viscosity. This is not preferred because of its difficulty and the capsule slurry has high viscosity and poor coatability.

Means for Solving the Problems In order to improve the above-mentioned conventional drawbacks, the present inventors have studied combinations of various system modifiers and wall materials, and as a result, have found that isobutylene / styrene / maleic anhydride ternary polymer is obtained. Merged or isobutylene / styrene / methyl acrylate /
When maleic anhydride quaternary polymer was used as a system modifier and melamine / formalin precondensate was used as a wall material, it had excellent thermoreversible color change ability and ground color (when in a decolored state,
Microcapsules with little residual color) could be easily obtained.

That is, the present invention provides (1) emulsifying a hydrophobic substance having a thermoreversible color change ability in an acidic aqueous solution containing a terpolymer of isobutylene / styrene / maleic anhydride, and then adding a melamine formalin precondensate. A method for producing thermoreversible color-changing microcapsules, characterized by forming a wall film by heat polymerization, and (2) an acid containing a quaternary copolymer of isobutylene / styrene / methyl acrylate / maleic anhydride. Production of thermoreversible microcapsules characterized by forming a wall film by emulsifying a hydrophobic substance having thermoreversible discoloration ability in an aqueous solution, then adding a melamine formalin precondensate and polymerizing by heating. It provides a method.

According to the method of the present invention, the stability of the emulsion of the hydrophobic substance is excellent and the viscosity is low, so that the encapsulation reaction is easily controlled and the production is easy. Further, the slurry of the microcapsules according to the present invention has excellent viscosity and low workability such as coatability.

In the present invention, a terpolymer of isobutylene / styrene / maleic anhydride is used as a system modifier that promotes emulsification. The molar ratio of this terpolymer is
When it is set to 100, isobutylene: styrene: maleic anhydride = 1-45: 5-55 :, about 30-70 (preferably 5-3
5: 15-45: 40-60). Its average molecular weight is about 4
It is 0000 to 200,000, preferably about 70,000 to 120,000. When the molecular weight is less than 40,000, the core substance lacks in emulsion stability,
If the system-modifying ability is insufficient and is larger than 120,000, the viscosity of the emulsion becomes high, so that the emulsion is apt to gel, and in either case, the reaction does not proceed properly. As this terpolymer,
Commercial products satisfying the above conditions can be widely used.
For example, ADVANTI ST19 (made by Idemitsu Petrochemical Co., Ltd.), ADVANTI ST28 (made by the company), ADVANTI ST
Examples include those marketed under a trade name such as ST46 (manufactured by the company).

Further, as the system modifier in the present invention, a quaternary copolymer of isobutylene / styrene / methyl acrylate / maleic anhydride can be used instead of the above terpolymer. The molar ratio of this quaternary copolymer was isobutylene: styrene: methyl acrylate: maleic anhydride = 1 to 35: 5
~ 45: 1 ~ 30: 30 ~ 70. Average molecular weight is about 70000
~ 120,000. As this quaternary copolymer, those commercially available under the trade name such as ADVANTI ST2812 (manufactured by Idemitsu Petrochemical Co., Ltd.) can be used.

The thermoreversible color-changing hydrophobic substance used as the capsule content in the present invention is a homogeneous mixture obtained by heating and dissolving a substantially water-insoluble leuco dye, a developer and a desensitizer, At room temperature, it may be liquid or solid. Usually 0.1 to 10 parts of leuco dye, 0.1 to 20 developers
Parts by weight and 70-99.8 parts by weight of desensitizer.

Known leuco dyes can be widely used and are not particularly limited. For example, triphenylmethanephthalides such as crystal violet lactone, malachite green lactone, 3,6-diethoxyfluoran, 3-dimethoxyamino-6-methyl-7-chlorofluoran,
Fluorans such as 2-benz-6-diethylaminofluoran and 3-diethylamino-7-methoxyfluoran; phenothiazines such as benzoylleucomethylene blue, methylleucomethylene blue, ethylleucomethylene blue and methoxybenzoylleucomethylene blue; 2- (phenylimino Indolylphthalides such as ethanedylidene) -3,3-dimethylindoline; 1,3,3-trimethyl-indolino-7-chloro-β-naphthospiropyran, di-β-naphthospiropyran, benzo-β-naphtho Spiropyrans such as spiropyran and xantho-β-naphthospiropyran; leukoauramines such as N-acetylauramine and N-phenylauramine; rosetamine B
Rosetamine lactams such as lactams.

The color developer is added to react with the leuco dye to form a color or discolor. As an appropriate developer,
Known ones can be widely used and are not particularly limited. For example, dodecylphenol, phenyl salicylate, dodecylphenol gallate, phenolic resin, 4-tert-butylphenol, 4-oxydiphenylether, α-
Naphthol, β-naphthol, p-oxybenzoic acid n-
Butyl, p-oxyacetophenone, 2,2'-methylenebis (4-methyl-6-tert-isobutylphenol), p-phenylphenol, 4,4'-isopropylidenediphenol, 2,2'-methylenebis (4- Chlorophenol), hydroquinone, 2-oxy-1-naphthoic acid, 2-oxy-p-toluic acid, salicylic acid, m
-Oxybenzoic acid, 4-oxyphthalic acid, phloroglucin carboxylic acid, gallic acid, propyl gallate, phthalic acid, and the like.In addition, phenolic hydroxyl groups disclosed in JP-B-52-30372 can be mentioned. And the metal salts thereof, carboxylic acids and metal salts thereof, sulfonic acids and metal salts thereof, and phosphate esters.
There may be mentioned 1,2,3-triazole compounds and the like disclosed in Japanese Patent No. 072.

The desensitizer prevents discoloration by suppressing the reaction between the leuco dye and the developer outside the predetermined temperature, and when the temperature reaches the predetermined temperature, the color is quickly changed and the discoloration (decoloration, color development) is reduced. Has a sharpening action. Known desensitizers can be widely used, and are not particularly limited. For example, n-octyl alcohol, n-nonyl alcohol, n-decyl alcohol, n-lauryl alcohol, n-myristyl alcohol, cetyl alcohol, n-stearyl alcohol, n-icosyl alcohol, n-docosyl alcohol, oleyl alcohol,
Alcohols such as cyclohexanol and benzyl alcohol; lauryl caproate, octyl caprate, butyl laurate, dodecyl laurate, hexyl myristate, myristyl myristate, octyl palmitate, stearyl palmitate, butyl stearate, cetyl stearate, Alcohols such as lauryl behenate, cetyl oleate, butyl benzoate, phenyl benzoate and dibutyl sebacate; ketones such as cyclohexane, acetophenone, benzophenone, dimyristyl ketone; caproic acid, caprylic acid, lauric acid, myristic acid, Palmitic acid, stearic acid, arachidic acid, behenic acid, lignoceric acid, cerotic acid, partoleic acid, oleic acid, ricinoleic acid, linolenic acid, eleostearic acid, elka Fatty acids and the like; capric acid amide, caprylic acid amide, lauric acid amide, myristic acid amide, palmitic acid, stearic acid amide,
Acid amides such as behenic acid amide, oleic acid amide and benzamide; aliphatic hydrocarbons such as decane, dodecane and undecane; aromatic hydrocarbons such as naphthalene, anthracene and diphenolmethane; decalin, pinene, bicyclohexyl and the like And a mixture of hydrocarbons commercially available as light oil or kerosene.

In the present invention, the hydrophobic substance is the above leuco dye,
Each of the color developer and the desensitizer may be contained singly or in combination of one or two or more, and forms a melt-mixed homogeneous mixture system.

The process for producing microcapsules of the present invention comprises the following two steps: (1) Terpolymer of isobutylene / styrene / maleic anhydride or quaternary copolymer of isobutylene / styrene / methyl acrylate / maleic anhydride. In the combined acidic aqueous solution,
Emulsify the thermoreversible hydrophobic substance.

(2) A capsule is made by reacting the emulsion obtained in the first step with the melamine / formalin initial shrinkage under acidic conditions and heating to form a melamine / formalin resin.

The pH during emulsification in the first step is less than about 6.5, preferably less than about 6.0. Above pH 6.5, the system becomes whipped and does not emulsify correctly. The emulsification temperature is 40-80 ° C, preferably 50-70 ° C. If the temperature is lower than 40 ° C., the hydrophobic substance may be precipitated in a wax state,
When the temperature is higher than 80 ° C., gelation is apt to occur, and the emulsion stability is deteriorated, so that the particle size of the dispersoid in the emulsion becomes uneven.

The terpolymer of isobutylene / styrene / maleic anhydride or the quaternary copolymer of isobutylene / styrene / methyl acrylate / maleic anhydride is about 2 to 20 parts by weight based on 100 parts by weight of the hydrophobic substance. Preferably about 4 to 10 parts by weight, more preferably about 6 to 8 parts by weight is used. When the amount is less than 2 parts by weight, the emulsion stability is poor, and when the amount is more than 20 parts by weight, the viscosity of the emulsion becomes high, so that the emulsion is easily gelled.

The second step is carried out at a temperature of 40 ° C. or higher, preferably 50 to 90 ° C., and is usually completed within 3 hours. pH is the pH of the emulsion of the hydrophobic substance obtained in the first step, and is 3.5 to 6.
5, preferably adjusted to 4.0 to 5.0. If the pH is less than 3.5, the reaction rate becomes excessive and the system gels. When the pH exceeds 6.5, the reaction rate decreases, and the strength of the wall becomes insufficient.

The initial condensate of melamine and formalin can be easily produced by an ordinary method by heating and dissolving. The molar ratio of melamine to formalin is preferably from 1: 2 to 10.

As the melamine / formalin initial condensate, a commercially available product can also be used. For example, Sumires Resin 615 (Sumitomo Chemical Co., Ltd.), Sumires Resin 613 (manufactured by the company), Sumires Resin 607 (manufactured by the company), Sumimar M50W (manufactured by the company), Sumimar M40W (manufactured by the company),
Sumimar M30W (manufactured by the company), Beckamine PMN (manufactured by the company), Milben Resin SM607 (manufactured by Showa Polymer), Milben Resin SM606 (manufactured by the company), Milben Resin SM615 (manufactured by the company), Euramine T-33 (manufactured by Mitsui Toatsu), Examples include those marketed under the trade name of Euramine T-34 (manufactured by the company).

The melamine / formalin precondensate is used in an amount of about 1 to 0.05 part by weight based on 1 part by weight of the hydrophobic substance emulsion. 0.
If the amount is less than 05 parts by weight, the capsules cannot be completely formed. If the amount exceeds 1 part by weight, the capsules may coagulate or gel.

Microcapsules obtained by the production method of the present invention,
Printed materials, clothing,
It can be used for various things such as tableware.

Hereinafter, specific examples of the thermoreversible color-changing microcapsules will be described in Examples, but the present invention is not limited thereto.

Examples Example 1 30 g of a terpolymer of isobutylene / styrene / maleic anhydride (35 mol: 15 mol: 50 mol) having a molecular weight of about 70,000 (trade name: Advanty ST19, manufactured by Idemitsu Petrochemical Co., Ltd.), sodium hydroxide 9 g and 461 g of water were dissolved by heating and stirring at 80 ° C. for 2 hours, and the resulting system modifier solution was used as solution A.

1.5 g of 1,2-benz-6-diethylaminofluoran,
2,2-propylidenebisphenol 3 g, lauric acid 45 g,
25 g of myristic acid and 30 g of palmitic acid were heated and melted at 80 ° C., and the resulting melted thermoreversible discolored hydrophobic substance was used as Liquid B.

4 g of melamine and 16 g of a 37% formalin aqueous solution were heated and dissolved at 50 ° C., and the resulting aqueous solution of melamine / formalin precondensate was used as liquid C.

While maintaining 100 g of the liquid A at 60 ° C., 90 g of the liquid B was added thereto with stirring with a homomixer, and emulsified at 4000 rpm for 5 minutes. The particle size of the dispersoid in the emulsion was 2 to 5 μm, and the pH of the emulsion was 5.6. Then, acetic acid 2.5 was added to this emulsion.
The mixture was adjusted to pH 4.6, 20 g of solution C was added, and the mixture was stirred at 60 ° C. for 2 hours to conduct a polymerization condensation reaction. Thereafter, the mixture was cooled to room temperature to obtain a slurry of microcapsules.

Example 2 Isobutylene / styrene / maleic anhydride (25 mol: 2
5 mol: 50 mol) terpolymer (molecular weight: about 100,000, trade name:
30 g of Advanti ST28, manufactured by Idemitsu Petrochemical Co., Ltd., 9 g of sodium hydroxide, and 461 g of water were dissolved by heating and stirring at 80 ° C. for 2 hours, and the resulting system modifier solution was used as solution A.

 The same liquid as in Example 1 was used as the liquid B and the liquid C.

While maintaining 100 g of the liquid A at 60 ° C., 90 g of the liquid B was added thereto with stirring with a homomixer, and emulsified at 4000 rpm for 5 minutes. The particle size of the dispersoid in the emulsion was 2 to 5 μm, and the pH of the emulsion was 5.7. Then, acetic acid 2.5 was added to this emulsion.
The mixture was adjusted to pH 4.7, 20 g of solution C was added, and the mixture was stirred at 60 ° C. for 2 hours to conduct a polymerization condensation reaction. Thereafter, the mixture was cooled to room temperature to obtain a slurry of microcapsules.

Example 3 Isobutylene / styrene / maleic anhydride (5 mol: 4
5 mol: 50 mol) terpolymer (molecular weight: about 100,000, trade name:
30 g of Advanti ST46, manufactured by Idemitsu Petrochemical Co., Ltd., 8 g of sodium hydroxide, and 462 g of water were dissolved by heating and stirring at 80 ° C. for 2 hours, and the resulting system modifier solution was used as solution A.

 Liquid B and liquid C used were the same as those in Example 1.

While maintaining 100 g of the liquid A at 60 ° C., 90 g of the liquid B was added thereto with stirring with a homomixer, and emulsified at 4000 rpm for 5 minutes. The particle size of the dispersoid in the emulsion was 2 to 5 μm, and the pH of the emulsion was 5.5. Next, acetic acid 2.0 was added to this emulsion.
The mixture was adjusted to pH 4.6, 20 g of solution C was added, and the mixture was stirred at 60 ° C. for 2 hours to conduct a polymerization condensation reaction. Thereafter, the mixture was cooled to room temperature to obtain a slurry of microcapsules.

Comparative Example 1 Isobutylene / maleic anhydride having a molecular weight of about 60,000 (50
Mol: 50 mol) 5 g of a copolymer (trade name: Isovan-04, manufactured by Kuraray Co., Ltd.), 2 g of sodium hydroxide and 93 g of water at 80 ° C.
The mixture was dissolved under heating with stirring for 2 hours to obtain a solution A.

 The same liquid as in Example 1 was used as the liquid B and the liquid C.

Since the pH of the solution A was 9.5, 2.5 ml of acetic acid was added thereto to adjust the pH to 5.
Adjusted to 1. Next, while maintaining 100 g of solution A at 60 ° C.
90 g of Liquid B was added while stirring with a homomixer. 4000r
It was not emulsified when stirred at pm. So, acetic acid 5m
l was added to adjust the pH to 4.5, but the operation was stopped without emulsification.

Comparative Example 2 Styrene / maleic anhydride having a molecular weight of about 50,000 (50 mol:
50 g) copolymer (Script set # 520, manufactured by Monsanto Co.) 5 g, sodium hydroxide 1.6 g and 94 g at 80 ° C.
The solution was dissolved by heating and stirring for a period of time to obtain a solution A.

 The same liquid as in Example 1 was used as the liquid B and the liquid C.

Since the pH of solution A was 10.4, 0.5 ml of acetic acid was added,
Adjusted to 6.4. Next, while maintaining 100 g of the solution A at 90 ° C., 90 g of the solution B was added with stirring using a homomixer. Four
When the emulsion was emulsified at 000 rpm for 5 minutes, the emulsification was not uniform due to the high viscosity of the emulsion, resulting in incomplete emulsification. The pH of the obtained emulsion was 5.4 (when the pH was 4.5 to 5.0, the emulsification system was solidified at the same time as the mixing of the liquid C, and in this case, the pH was not adjusted with acetic acid). The solution C was added to the emulsion, and the mixture was stirred at 60 ° C. for 2 hours to perform a polycondensation reaction. However, the stirring was difficult due to the high viscosity of the reaction solution. Thereafter, the mixture was cooled to room temperature to obtain a slurry of microcapsules, but the viscosity of the slurry was too high to measure.

Comparative Example 3 50 g of Liquid A used in Comparative Example 1 and 50 g of Liquid A used in Comparative Example 2
Was used as a solution A.

 The same liquid as in Example 1 was used as the liquid B and the liquid C.

Since the pH of the solution A was 9.9, 1 ml of acetic acid was added, and the pH was adjusted to 6.3.
Was adjusted. Next, while maintaining 100 g of solution A at 60 ° C.,
90 g of the liquid was added while stirring with a homomixer. 4000rpm
When the emulsion was emulsified for 5 minutes, the viscosity of the emulsion was high, and the hydrophobic substance melt (liquid B) floated on the surface of the emulsion, resulting in incomplete emulsification. The pH of the obtained emulsion was 5.3.
Solution C was added to this emulsion, and the mixture was stirred at 60 ° C. for 2 hours to perform a polycondensation reaction. Thereafter, the slurry was cooled to room temperature to obtain a slurry of microcapsules, but the slurry was solidified the next day.

Comparative Example 4 Ethylene / maleic anhydride having a molecular weight of about 100,000 (50: 5
0) 5 g of a copolymer (trade name: EMA31, manufactured by Monsanto Co.) and 95 g of water were heated and stirred at 80 ° C. for about 2 hours to obtain a liquid A.

 Liquid B used was the same as in Example 1.

6 g of urea and 0.9 g of resorcinol were added to 100 g of the liquid A, and 90 g of the liquid B was added while stirring at 60 ° C. with a homomixer. Emulsified at 4000 rpm for 5 minutes. The particle size of the dispersoid in the emulsion was 2 to 5 μm, and the pH of the liquid was 2.0. Next, 1 ml of 20% sodium hydroxide was added to the emulsion, and the pH was adjusted.
Adjusted to 3.2. 15.6 g of formalin was added thereto, and the mixture was stirred at 60 ° C. for 2 hours to conduct a polymerization condensation reaction. Thereafter, the mixture was cooled to room temperature to obtain a slurry of microcapsules.

Comparative Example 5 Liquid A and liquid B were the same as those in Comparative Example 4.

 The same liquid as that in Example 1 was used as the liquid C.

To 100 g of solution A, 3 ml of 20% sodium hydroxide was added to adjust the pH to 4.0. Next, while maintaining the solution A at 60 ° C., 90 g of the solution B
Was added with stirring with a homomixer, and emulsified at 4000 rpm for 5 minutes. The particle size of the dispersoid in the emulsion is 2 to 5 μm
The pH of the solution was 3.9. Then, when the liquid C was added to the emulsion, the solution gelled in about 1 minute, but was stirred at 60 ° C. for 2 hours to conduct a polymerization condensation reaction. Thereafter, the mixture was cooled to room temperature to obtain a slurry of microcapsules.

Example 4 As the solution A, the same one as in Example 2 was used.

1.5 g of 3,3-bis (4-dimethylaminophenyl) -6-dimethylaminophthalide, 3 g of methyl-isobutyl-methylidene-bisphenol and 100 g of cetyl alcohol
The mixture was heated and melted at 80 ° C. to obtain a liquid B.

 The same liquid as in Example 1 was used as the liquid C.

While keeping 100 g of the liquid A at 60 ° C., 90 g of the liquid B was added with stirring with a homomixer, and emulsified at 4000 rpm for 5 minutes.
The particle size of the dispersoid in the emulsion is 2 to 5 μm, and the pH of the liquid is 5.
It was 6. 2.5 ml of acetic acid was added thereto to adjust the pH to 4.6. Next, the liquid C was added to the emulsion, and the mixture was stirred at 60 ° C. for 2 hours to perform a polymerization condensation reaction. Thereafter, the mixture was cooled to room temperature to obtain a slurry of microcapsules.

Example 5 The same liquid as that in Example 2 was used as the liquid A.

1,3-dimethyl-6-diethylaminofluoran 2 g,
4 g of methyl p-hydroxybenzoate and 100 g of methyl stearate were heated and melted at 80 ° C. to obtain a liquid B.

 The same liquid as in Example 1 was used as the liquid C.

While keeping 100 g of the liquid A at 60 ° C., 90 g of the liquid B was added with stirring with a homomixer, and emulsified at 4000 rpm for 5 minutes.
The particle size of the dispersoid in the emulsion is 2 to 5 μm, and the pH of the liquid is 5.
It was 6. 2.5 ml of acetic acid was added thereto to adjust the pH to 4.6. Next, the liquid C was added to the emulsion, and the mixture was stirred at 60 ° C. for 2 hours to perform a polymerization condensation reaction. Thereafter, the mixture was cooled to room temperature to obtain a slurry of microcapsules.

Comparative Example 6 The same operation was performed as in Comparative Example 1, except that the solution B was changed to the one used in Example 4.

Solution A had a pH of 9.5, and was adjusted to pH 5.1 by adding 2.5 ml of acetic acid. Next, while maintaining 100 g of solution A at 60 ° C.,
g was added with stirring with a homomixer, and the mixture was stirred at 4000 rpm, but did not emulsify. 5 ml of acetic acid was added, and the pH was further increased.
The operation was stopped because the emulsion was not emulsified.

Comparative Example 7 The same procedure was performed as in Comparative Example 1, except that the solution B was replaced with the one used in Example 5.

Solution A had a pH of 9.5, and was adjusted to pH 5.1 by adding 2.5 ml of acetic acid. Next, while maintaining 100 g of solution A at 60 ° C.,
g was added with stirring with a homomixer, and the mixture was stirred at 4000 rpm, but did not emulsify. 5 ml of acetic acid was added,
The operation was stopped because the emulsion was not emulsified.

Example 6 As the solution A, the same one as in Example 2 was used.

1.5 g of 3-diethylamino-6-methyl-7-chlorofluorane, 4,4'-thiobis (3-methyl-6-tert-
3 g of butylphenol), 60 g of lauryl alcohol and 40 g of myristic amide were heated and melted at 80 ° C. to obtain a liquid B.

 The same liquid as in Example 1 was used as the liquid C.

While keeping 100 g of the liquid A at 60 ° C., 90 g of the liquid B was added with stirring with a homomixer, and emulsified at 4000 rpm for 5 minutes.
The particle size of the dispersoid in the emulsion is 2 to 5 μm,
pH was 5.6. Then, 2.5 ml of acetic acid was added to this emulsion to adjust the pH to 4.6, and the solution C was added, followed by stirring at 60 ° C. for 2 hours to carry out a polymerization condensation reaction. Then cool to room temperature,
A slurry of microcapsules was obtained.

Example 7 As the solution A, the same one as in Example 2 was used.

2 g of 3,3-bis (4-dimethylaminophenyl) -6-dimethylaminophthalide, 4 g of 2,2-propylidenebisphenol, 60 g of lauryl alcohol and 40 g of myristic amide were heated and melted at 80 ° C. did.

 The same liquid as in Example 1 was used as the liquid C.

While keeping 100 g of the liquid A at 60 ° C., 90 g of the liquid B was added with stirring with a homomixer, and emulsified at 4000 rpm for 5 minutes.
The particle size of the dispersoid in the emulsion is 2 to 5 μm,
pH was 5.6. Then, 2.5 ml of acetic acid was added to this emulsion to adjust the pH to 4.6, and the solution C was added, followed by stirring at 60 ° C. for 2 hours to carry out a polymerization condensation reaction. Then cool to room temperature,
A slurry of microcapsules was obtained.

Comparative Example 8 Comparative Example 2 except that the liquid B was used in Example 6.
Was performed in the same manner as described above.

The pH of Solution A was 10.6, and the pH was adjusted to 6.5 by adding 0.5 ml of acetic acid. Next, while maintaining 100 g of solution A at 60 ° C.,
90 g was added with stirring with a homomixer. When the emulsion was emulsified at 4000 rpm for 5 minutes, the emulsified liquid was high in viscosity, so that the emulsification was not uniform and was incomplete. The pH of the obtained emulsion was 5.5. Solution C is added to this emulsion,
For 2 hours to carry out a polycondensation reaction, but the stirring was difficult due to the high viscosity of the reaction solution. Thereafter, the mixture was cooled to room temperature to obtain a slurry of microcapsules, but the viscosity of the slurry was too high to measure.

Comparative Example 9 Comparative Example 2 except that the liquid B was used in Example 7.
Was performed in the same manner as described above.

The pH of Solution A was 10.6, and the pH was adjusted to 6.5 by adding 0.5 ml of acetic acid. Next, while maintaining 100 g of solution A at 60 ° C.,
90 g was added with stirring with a homomixer. When the emulsion was emulsified at 4000 rpm for 5 minutes, the emulsified liquid was high in viscosity, so that the emulsification was not uniform and was incomplete. The pH of the obtained emulsion was 5.5. Solution C is added to this emulsion,
For 2 hours to carry out a polycondensation reaction, but the stirring was difficult due to the high viscosity of the reaction solution. Thereafter, the mixture was cooled to room temperature to obtain a slurry of microcapsules, but the viscosity of the slurry was too high to measure.

Example 8 The same liquid as that used in Example 2 was used as the liquid A.

3-ethylanilino-7-methylanilinofluoran
1.5 g, 3,4'-thiobis (3-methyl-6-tert-butylphenol), 3 g, myristic acid 50 g, and methyl stearate 50 g were heated and melted at 80 ° C. to obtain a liquid B.

 The same liquid as that used in Example 2 was used as the liquid C.

While keeping 100 g of the liquid A at 60 ° C., 90 g of the liquid B was added with stirring with a homomixer, and emulsified at 4000 rpm for 5 minutes.
The particle size of the dispersoid in the emulsion is 2 to 5 μm,
pH was 5.5. Then, 2.5 ml of acetic acid was added to this emulsion to adjust the pH to 4.6, and the solution C was added, followed by stirring at 60 ° C. for 2 hours to carry out a polymerization condensation reaction. Thereafter, the mixture was cooled to room temperature to obtain a slurry of microcapsules.

Example 9 The same liquid as that used in Example 2 was used as the liquid A.

3 g of 3-diethylamino-6-methyl-7-anilinofluoran, 2 g of methyl p-hydroxybenzoate, 50 g of lauric acid and 50 g of cetyl alcohol were heated and melted at 80 ° C.
Solution B was used.

 The same liquid as that used in Example 2 was used as the liquid C.

While keeping 100 g of the liquid A at 60 ° C., 90 g of the liquid B was added with stirring with a homomixer, and emulsified at 4000 rpm for 5 minutes.
The particle size of the dispersoid in the emulsion is 2 to 5 μm,
pH was 5.4. Then, 2.5 ml of acetic acid was added to this emulsion to adjust the pH to 4.6, and the solution C was added, followed by stirring at 60 ° C. for 2 hours to carry out a polymerization condensation reaction. Then cool to room temperature,
A slurry of microcapsules was obtained.

Comparative Example 10 Liquids A and C used were the same as those used in Comparative Example 3.

Liquid B used was the same as that used in Example 8.

Since the pH of the solution A was 9.9, 1 ml of acetic acid was added, and the pH was adjusted to 6.3.
Was adjusted. Next, while maintaining 100 g of solution A at 60 ° C.,
90 g of the liquid was added while stirring with a homomixer. 4000rpm
When the emulsion was emulsified for 5 minutes, the viscosity of the emulsion was high, and the hydrophobic substance melt (liquid B) floated on the surface of the emulsion, resulting in incomplete emulsification. The pH of the obtained emulsion was 5.2.
Solution C was added to this emulsion, and the mixture was stirred at 60 ° C. for 2 hours to perform a polycondensation reaction. Thereafter, the slurry was cooled to room temperature to obtain a slurry of microcapsules, but the slurry was solidified the next day.

Comparative Example 11 Liquids A and C used were the same as those used in Comparative Example 3.

Liquid B used was the same as that used in Example 9.

Since the pH of the solution A was 9.9, 1 ml of acetic acid was added, and the pH was adjusted to 6.3.
Was adjusted. Next, while maintaining 100 g of solution A at 60 ° C.,
90 g of the liquid was added while stirring with a homomixer. 4000rpm
When the emulsion was emulsified for 5 minutes, the viscosity of the emulsion was high, and the hydrophobic substance melt (liquid B) floated on the surface of the emulsion, resulting in incomplete emulsification. The pH of the obtained emulsion was 5.4.
Solution C was added to this emulsion, and the mixture was stirred at 60 ° C. for 2 hours to perform a polycondensation reaction. Thereafter, the slurry was cooled to room temperature to obtain a slurry of microcapsules, but the slurry was solidified the next day.

Example 10 Isobutylene / styrene / methyl acrylate / maleic anhydride having a molecular weight of about 100,000 (15 mol: 25 mol: 10 mol: 50)
Mol) quaternary copolymer (Advanti STAM2812, Idemitsu Petrochemical Co., Ltd.) 40 g, sodium hydroxide 8 g and water 452 g
The mixture was heated and dissolved under stirring at about 2 hours for about 2 hours, and the resulting system modifier was used as solution A.

3-cyclohexylmethylamino-6-methyl-7-
1.5 g of aninofluorane, 3 g of benzotriazole and 100 g of cetyl alcohol were heated and melted at 80 ° C., and the resulting thermoreversible discolored hydrophobic substance melt was used as liquid B.

Liquid C used was the same as that used in Example 1.

While keeping 100 g of the liquid A at 60 ° C., 90 g of the liquid B was added with stirring with a homomixer, and emulsified at 4000 rpm for 5 minutes.
The particle size of the dispersoid in the emulsion is 2 to 5 μm,
pH was 5.6. Next, 2.5 ml of acetic acid was added to this emulsion to adjust the pH to 4.6, 20 g of solution C was added, and the mixture was stirred at 60 ° C. for 2 hours to carry out a polymerization condensation reaction. Thereafter, the mixture was cooled to room temperature to obtain a slurry of microcapsules.

Example 11 The same liquid as that used in Example 2 was used as the liquid A.

1.5 g of 1,2-benz-6-diethylaminofluoran,
Liquid B was obtained by heating and melting 3 g of bisphenol S and 100 g of palmitic acid at 80 ° C.

16 g of melamine / formalin initial condensate (trade name: Sumires Resin 615, manufactured by Sumitomo Chemical Co., Ltd.) and 14 g of water
Was dissolved by stirring to obtain a liquid C.

While keeping 100 g of the liquid A at 60 ° C., 90 g of the liquid B was added with stirring with a homomixer, and emulsified at 4000 rpm for 5 minutes.
The particle size of the dispersoid in the emulsion is 2 to 5 μm,
pH was 5.7. Then add 5 ml of 50% tartaric acid to this emulsion
Was added to adjust the pH to 4.0, 30 g of solution C was added, and the mixture was stirred at 60 ° C. for 2 hours to carry out a polymerization condensation reaction. Thereafter, the mixture was cooled to room temperature to obtain a slurry of microcapsules.

Example 12 A slurry of microcapsules was obtained in the same manner as in Example 2 except that the following components were used for the solution B.

2,3-dibutylamino-6-methyl-7-anilinofluorane 1.5 g 2,2-propylidenebisphenol 3 g lauric acid 60 g disteary ketone 40 g Test Example 1 Obtained in Examples 1 to 12 and Comparative Examples 1 to 11. Using the slurry of the microcapsules thus obtained, printing was performed on white Kent paper with a silk screen (100 mesh) and air-dried. When coloration of the resulting printing coating chromaticity ^{(20 ℃) (L *,} a *, b *) and chromaticity during discoloring ^{(40 ℃) (L *,} a *, b *) (40 ℃ ) Was measured. The measurement was performed using a colorimeter (CR 100, manufactured by Minolta). The color difference ΔE was determined by the following equation.

^{ΔE = X 2 + Y 2 +} Z 2 L *: lightness index a ^*, b ^*: hue, chromatic Ness index for chroma _{^{L 0 *, a 0 *,}} b 0 *: standard white board chromaticity (L ₀ ^* = ^{_{95.08, a 0 * = -0.5,}} b 0 * = -0,78) X = L * -L 0 * Y = a * -a 0 * Z = b * -b 0 *

Claims (2)

(57) [Claims] 1. A method for emulsifying a hydrophobic substance having a thermoreversible discoloration ability in an acidic aqueous solution containing a terpolymer of isobutylene / styrene / maleic anhydride, followed by addition of a melamine formalin precondensate, followed by heat polymerization. A method for producing thermoreversible discolorable microcapsules, characterized by forming a wall film. 2. After emulsifying a hydrophobic substance having a thermoreversible color change ability in an acidic aqueous solution containing a quaternary copolymer of isobutylene / styrene / methyl acrylate / maleic anhydride,
A method for producing a thermoreversible color-changing microcapsule, wherein a wall film is formed by adding a melamine formalin precondensate and subjecting it to heat polymerization.