JPH05237370A - Continuous production of microcapsule - Google Patents

Abstract

PURPOSE:To continuously produce microcapsules having polyvinyl alcohol wall films by introducing a water-base dispersion or soln. of solid particles and water into a porous glass pipe and utilizing the chelate reaction of a polyvinyl alcohol-zirconium chloride mixture soln. with an alkali aq. soln. CONSTITUTION:A water-base dispersion or soln. of solid particles is stored in a storage tank 1, while an alkali aq. soln. or a mixture soln. of polyvinyl alcohol or its deriv. and zirconium chloride is stored in a storage tank 2. Both liquids stored in the tanks 1, 2 are supplied at each specified flow rate and mixed at a junction 9 and introduced to a porous glass pipe 13. At the same time, a mixture soln. of polyvinyl alcohol or its deriv and zirconium chloride, or alkali aq. soln. stored in a storage tank 3 is introduced at a specified flow rate to an emulsifying tank 12. The material to be included in microcapsules is made to transmit through the pipe 13 under pressure to produce emulsified particles. These particles are precoated with polyvinyl alcohol and then passed through a tubular reactor 16 to continuously produce microcapsules.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuous process for producing microcapsules. More specifically, the present invention relates to a continuous production method of microcapsules capable of producing microcapsules containing solid particles and water (or an aqueous solution).

[0002]

2. Description of the Related Art Microcapsules are minute containers. Various functional materials can be contained in the container and released temporarily or with time.
The materials are diverse and include dyes and pigments, pharmaceuticals,
Examples include foods, catalysts, adhesives, cosmetics, fragrances, recording materials, magnetic materials, liquid crystals, agricultural chemicals, fertilizers, seeds and the like.

The applications of the microcapsules are various as described above, and among them, the pressure-sensitive copying paper is particularly familiar. A pressure-sensitive copying paper is a coating in which microcapsules containing a solution (that is, an oily liquid) in which an electron-donating colorless or light-colored dye precursor is dissolved in a non-volatile solvent are coated on a support. It prints and records by stacking the coated surfaces of coated paper (upper paper) and coated paper (lower paper) coated with an electron-accepting acidic substance, and applying pressure with a means such as writing pressure. is there.

As the method for producing such microcapsules, there are physical methods such as a spray drying method, an air suspension coating method, a spray granulation method, a pan coating method and an orifice method,
Mechanical method, or complex coacervation method, interfacial polymerization method, in situ method, in-liquid hardening coating method,
A physicochemical method such as an in-liquid drying method and a melt dispersion cooling method can be used. In the production method of these microcapsules,
The above-mentioned pressure-sensitive copying paper utilizing the interfacial polymerization method and the in-situ method is general and is familiar. The microcapsules used for pressure-sensitive copying paper have an oily liquid as an internal component.

On the other hand, a microcapsule containing an aqueous liquid is physically formed by a spray drying method, an orifice method, or the like.
It can be produced by a physicochemical method such as a mechanical method, an interfacial polymerization method, an in situ method, a liquid hardening coating method, a liquid drying method, and a melt dispersion cooling method. Among these, several μm
An interfacial polymerization method and an in situ method are mentioned as a manufacturing method of the microcapsule which can manufacture a microcapsule with a particle size of several tens of micrometers and a uniform particle. However, these methods are of the W / O type, that is, emulsified form of water in oil, and require removal of oil (non-aqueous liquid such as organic solvent).

Further, the interfacial polymerization method and the in situ method for producing microcapsules are mainly batch method, which is a conventional method.
As long as the tu method is used, the only measure to increase the size of equipment is to increase the production of microcapsules.

By the way, the inventor of the present invention has disclosed in Japanese Patent Laid-Open No. 3-114
Japanese Patent No. 528 proposes a microcapsule in which a core substance is included as a wall film of a mixture of polyvinyl alcohol and / or a derivative thereof and zirconium chloride, and a method for producing the same. Here, an orifice method is used, and a manufacturing method by an in-liquid curing method or a spray drying method is exemplified. However, there is still room for improvement, for example, there is a limit to the nozzle diameter by the orifice method, and it is difficult to obtain a uniform particle diameter in continuous production.

Various studies have been conducted on the continuous production method of microcapsules, for example, Japanese Patent Publication No. 52-2.
No. 2829, No. 52-49797, Japanese Patent Publication No. 3
-46170 publication can be mentioned.

Japanese Patent Publication No. 52-22829 discloses a method for performing liquid-liquid separation in a tubular capsule manufacturing conduit having a single inlet and a single outlet. Japanese Patent Publication No. 52-49
In Japanese Patent Publication No. 797, Japanese Patent Publication No. 52-22, except that a plurality of inlet portions and a single outlet portion are provided in a capsule manufacturing conduit.
The method is the same as that of Japanese Patent No. 829. These publications are not only constrained in that the vehicle for capsule production must be passed through the conduit under turbulent flow conditions in order to prevent the immature capsules from aggregating during the capsule formation process. It is necessary to keep the temperature gradient along with and cover the target capsule core material with the wall material.

As an improvement of these two inventions, there is Japanese Patent Publication No. 3-46170. In the publication,
When introducing a mixture of capsule core material, water-soluble capsule wall precursor, and aqueous vehicle for capsule production containing negatively charged polyelectrolyte into the tube, turbulent flow is not required and the emulsion that has passed through the emulsifier is tubular-reacted. It is described that the microcapsules are continuously produced while the tubular reactor is maintained at a single high temperature while being guided to a vessel, and there is no agglomeration of the capsules and no solid substance deposition occurs in the reaction vessel.

In each of the above publications, the water-soluble capsule wall precursor comprises, for example, low molecular weight methylol melamine, etherified methylol melamine, methylated methylol melamine, melamine / formaldehyde resin, and the like. A substantially water-insoluble liquid,
That is, an oily liquid is used.

[Problems to be Solved by the Invention]

As described above, in the conventional continuous production method of microcapsules, from the system in which the capsule core substance (the microcapsule inclusion in the present invention) is an oily liquid, this is made into an aqueous liquid and is different from the conventional water-soluble capsules. An aqueous liquid is encapsulated by using a wall precursor (water-soluble microcapsule wall material aqueous solution according to the present invention), which provides a continuous production method of microcapsules capable of uniforming particle diameter and forming a uniform film. The purpose is that.

[Means for Solving the Problems]

As a result of intensive studies, the present inventor provides a continuous production method of microcapsules capable of producing microcapsules having a uniform particle size.

That is, the continuous production method of microcapsules provided by the present invention is a continuous production method of microcapsules containing an aqueous dispersion liquid of at least one or more solid particles or an aqueous solution thereof, wherein the microcapsule inclusions are: An aqueous dispersion of the solid particles or an aqueous solution thereof together with water, and an aqueous alkali solution or a mixed aqueous solution of polyvinyl alcohol or a derivative thereof and zirconium chloride. The following 1) to 8: According to the process (1), microcapsules containing the aqueous dispersion of the solid particles or the aqueous solution thereof are continuously produced. 1) An aqueous dispersion of the solid particles or an aqueous solution thereof stored in the first storage tank and an alkaline aqueous solution or a mixed aqueous solution of polyvinyl alcohol or its derivative and zirconium chloride stored in the second storage tank are kept constant, respectively. A step of forming a mixed state by supplying at a flow rate into the tubular portion and mixing at the confluence. 2) In the tubular part or the spiral tubular part connected to the confluence,
A step of continuously passing the mixed liquid at a constant flow rate to introduce the mixed liquid into a porous glass pipe. 3) Simultaneously with the above 2), a step of supplying a mixed aqueous solution of polyvinyl alcohol or its derivative and zirconium chloride or an alkaline aqueous solution stored in a third storage tank into the tubular portion at a constant flow rate and introducing the same into the emulsification tank. 4) A step of allowing the microcapsule inclusions to permeate the porous glass pipe having fine pores under pressure to form emulsified particles in the emulsification tank. 5) A step of pre-coating the surface of the emulsified particles with polyvinyl alcohol. 6) A step of introducing an emulsion of pre-coated emulsion particles into the tubular portion. 7) A step of continuously passing the emulsion through a tubular reactor maintained at a constant temperature. 8) A step of passing through the tubular reactor to the tubular portion and taking out the formed microcapsules from the discharge portion.

In the present invention, the solid particles are one or more selected from the group consisting of an electron-donating colorless dye, an electron-accepting developer and a sensitizer. ..

According to the present invention, the temperature in the tubular reactor maintained at a constant temperature is 30 to 90 ° C.

In the present invention, the porous glass pipe is
It is characterized by having a pore diameter of 0.2 to 100 μm.

The porous glass pipe of the present invention is not particularly limited as long as it is made of porous glass having characteristics such as mechanical strength and heat resistance.
CaO-B disclosed in JP-B-62-25618
₂ O ₃ —SiO ₂ —Al ₂ O ₃ -based porous glass, JP-A-61
CaO-B ₂ O ₃ -Si disclosed in -40841 JP
_{O 2 -Al 2 O 3 -Na 2} O -based porous glass and CaO-B
₂ O ₃ —SiO ₂ —Al ₂ O ₃ —Na ₂ O—MgO based porous glass is preferable. The porous glass pipe used here has a pore size of submicron to micron order. When emulsifying using the material to be emulsified (microcapsule inclusion), in order to obtain the desired emulsified particles, select a porous glass pipe having a pore size corresponding to the particle size and A desired emulsified particle can be obtained by introducing it into a high-quality glass pipe under pressure and allowing it to permeate through the fine pores.

When pressure is applied using the porous glass pipe of the present invention, the pressure varies depending on the type of liquid used, solution viscosity, temperature, etc., but is usually 0.01 to 10 Kg.
/ Cm ² , which can be appropriately changed and used.

The tubular reactor used in the present invention is a thermostatic bath maintained at a constant temperature with a folded tubular portion, and microencapsulation is performed between the inlet and outlet of the tubular portion. It was done like this. Microencapsulation is performed by controlling the length of the tubular portion, the flow rate through the tubular portion, and the residence time, and can be appropriately changed depending on the type of microcapsule inclusion and water-soluble microcapsule wall material. However, it is possible to select suitable conditions in advance.

The tubular portion used in the present invention may be a commonly used circular tube. In particular, in the present invention, when two kinds of liquids are merged and mixed, the spiral tubular portion is used, but by using this, effective mixing is performed. The two or more liquids passing through the spiral tubular section can be uniformly mixed during the passage because they create a turbulent state in the tube. Here, the spiral tubular portion is one in which a spiral tube is enclosed in a circular tube, or the entire shape is a spiral tube.

The steps of the continuous production method of the microcapsules of the present invention will be described below with reference to FIG. It is assumed that the microcapsule inclusion is an aqueous dispersion of solid particles.

In the first step, the aqueous dispersion of solid particles (including water) stored in the first storage tank 1 is supplied to the tubular portion 7 via the supply pump 4. At the same time, the alkaline aqueous solution or the mixed aqueous solution of polyvinyl alcohol or its derivative and zirconium chloride stored in the second storage tank 2 is supplied to the tubular portion 8 via the supply pump 5. The two aqueous solutions supplied are combined at the confluence point 9 and mixed to form a mixed state. Here, when one or more aqueous dispersions of solid particles are used, the number of storage tanks may be appropriately increased or decreased depending on the storage stability of the mixed aqueous dispersion. For example, in an aqueous dispersion of an electron-donating colorless dye and an electron-accepting developer, when mixed and stored for a long period of time, a color reaction (liquid fog) occurs between them. In such a case, it is preferable to use two storage tanks. The alkaline aqueous solution stored in the storage tank 2 may be a mixed aqueous solution of polyvinyl alcohol or its derivative and zirconium chloride depending on the compatibility with the aqueous dispersion of solid particles. At this time, the storage tank 3 stores the alkaline aqueous solution.

In the second step, the mixed liquid merged at the merge point 9 is continuously passed through the tubular portion or the spiral tubular portion 10 at a constant flow rate and introduced into the porous glass pipe 13.
The mixed liquid tends to be homogenized in the process of passing through the tubular portion, but the effect is enhanced by replacing the tubular portion with the spiral tubular portion.

At the same time as the second step, in the third step, a mixed aqueous solution of polyvinyl alcohol or its derivative and zirconium chloride stored in the third storage tank 3 or an alkaline aqueous solution is supplied at a constant flow rate through the supply pump 6. Is supplied into the tubular portion 11 and introduced into the emulsification tank 12. First
In the step, when the storage tank 2 stores the mixed aqueous solution of polyvinyl alcohol or its derivative and zirconium chloride, the storage tank 3 stores the alkaline aqueous solution.

In the fourth step, the microcapsule inclusions are permeated through the porous glass pipe 13 having fine pores under pressure to form emulsified particles in the emulsification tank 12.

In the fifth step, the surface of the emulsified particles is precoated with polyvinyl alcohol. When the emulsion particles are formed by passing through the fine pores of the porous glass pipe, the alkaline aqueous solution in the emulsion particles, a mixed aqueous solution of polyvinyl alcohol or a derivative thereof and zirconium chloride are contacted at the emulsion particle interface. , Insolubilizes polyvinyl alcohol. The insolubilization of polyvinyl alcohol depends on zirconium ions.

In the sixth step, the emulsion of precoated emulsion particles is introduced into the tubular portion 15.

In the seventh step, the tubular reactor 16 kept at a constant temperature is continuously passed. The emulsified particles pre-coated in the fifth step are heated to promote insolubilization of the polyvinyl alcohol wall film on the coated surface.

In the eighth step, through the tubular reactor 16,
After passing through the tubular portion 19, the microcapsules formed from the discharge portion 20 are taken out. After passing through the tubular reactor 16, the surface of the emulsified particles becomes microcapsules completely insolubilized by the polyvinyl alcohol wall film.

By continuously advancing the above steps, it is possible to continuously produce microcapsules containing an aqueous dispersion of solid particles.

FIG. 2 illustrates the portion of the emulsification tank provided with the porous glass pipe of the continuous production apparatus for microcapsules described in FIG. 1. The emulsification tank 23 has two porous glass pipes 24. The attached state is shown. Figure 2
Then, a mixed liquid in the first storage tank (aqueous dispersion liquid of solid particles or an aqueous solution thereof) and the second storage tank (aqueous alkali solution or a mixed aqueous solution of polyvinyl alcohol or its derivative and zirconium chloride) is used as a tubular portion or a spiral. Two porous glass pipes 24 connected to the tubular portion 21 (corresponding to 10 in FIG. 1) are attached to the emulsification tank 24, and a third storage tank (mixed aqueous solution of polyvinyl alcohol or its derivative and zirconium chloride or alkali) is used. 1 shows a tubular portion 26 (corresponding to the tubular portion 15 in FIG. 1) that is connected from the aqueous solution) to the tubular portion 22 (corresponding to the tubular portion 11 in FIG. 1) and that is connected from the emulsification tank 23 to the tubular reactor. ing. Although FIG. 2 is shown as a schematic diagram in which two porous glass pipes are attached, emulsification can be effectively performed by attaching more porous glass pipes. In addition, in FIG. 1, in order to make it easy to understand, the porous glass pipe is shown as 1
It is described as a schematic diagram attached hereto, and the number of attached porous glass pipes is not limited. The same applies to FIG.

FIG. 3 shows a combination of the first and second storage tanks shown in FIG. In this case, the storage tank stores an aqueous dispersion or aqueous solution of solid particles treated with a mixed aqueous solution of alkali or polyvinyl alcohol or its derivative and zirconium chloride. The continuous production of microcapsules is substantially the same as the process described in FIG. When there are various types of aqueous dispersions of solid particles or aqueous solutions thereof to be included, the number of storage tanks may be increased and tubular portions or spiral tubular portions may be appropriately connected. The increase or decrease in the number of storage tanks is not limited in any way.

In the microencapsulation of the present invention, the insolubilization of polyvinyl alcohol depends on zirconium ions. Zirconium ion has a coordination number of 8
It is known that (maximum) is highly reactive, and it forms a chelate bond with a functional group such as a hydroxyl group, a carboxyl group, an amine group, etc., and produces an inactive substance by heat treatment. When zirconium chloride is mixed with polyvinyl alcohol, a hydrophilic complex of polyvinyl alcohol and a zirconium ion form a stable complex compound, and zirconium acts as a cross-linking agent between polyvinyl alcohol molecules by alkali treatment and drying, thereby forming a cross-linking structure. Form. Further, the zirconium ion bonds with the carbon atom of polyvinyl alcohol through the oxygen atom and becomes insoluble.

The polyvinyl alcohol or its derivative used in the present invention includes, for example, completely saponified polyvinyl alcohol, partially saponified polyvinyl alcohol and anion-modified polyvinyl alcohol.

Zirconium chloride used in the present invention is
For example, zirconium tetrachloride (ZrCl ₄ ), zirconyl chloride (ZrOCl ₂ ) basic zirconyl chloride (ZrO 4
Water-soluble chlorides of zirconium such as OHCl).

The alkaline aqueous solution used in the present invention includes aqueous solutions of sodium hydroxide, ammonium hydroxide, sodium carbonate, ammonium carbonate, sodium borate, sodium silicate, ammonium chloride and the like.

In the mixed aqueous solution of polyvinyl alcohol or its derivative of the present invention and zirconium chloride, the amount of zirconium chloride mixed with polyvinyl alcohol is 0.05 to 35 zirconium chloride (as ZrO ₂ ) per 100 parts by weight of polyvinyl alcohol. Parts by weight, preferably 0.5 to 20 parts by weight. 0.0
If it is less than 5 parts by weight, there is no effect, and if it exceeds 35 parts by weight, there is a drawback that it becomes cloudy during alkali treatment and the film strength becomes weak.

The solid particles used in the present invention include, for example, dyes and pigments, pharmaceuticals, foods, agricultural chemicals, catalysts, organic solvents,
Adhesives, cosmetics, fragrances, recording materials, magnetic materials, liquid crystals, fertilizers, seeds, enzymes and the like can be mentioned. In particular, the present invention can be applied to a heat-sensitive recording material by using an electron-donating colorless dye, an electron-accepting color developer, and a sensitizer as solid particles. The thermal recording material in this case is
Since it can be applied to a substrate while retaining water content, it has an advantage that thermal coloring (commonly known as background fog) can be prevented in the drying step. If the solid particles are water-soluble, they may be treated as an aqueous solution. Further, the present invention is characterized by including solid particles and water, but it is easier to include water instead of the organic solvent.

Specific examples of the electron-donating colorless dye used in the present invention include (1) triarylmethane compound 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (Crystal violet lactone), 3,3-bis (p-dimethylaminophenyl) phthalide, 3- (p-dimethylaminophenyl) -3-
(1,2-dimethylindol-3-yl) phthalide,
3- (p-dimethylaminophenyl) -3- (2-methylindol-3-yl) phthalide, 3- (p-dimethylaminophenyl) -3- (2-phenylindole-
3-yl) phthalide, 3,3-bis (1,2-dimethylindol-3-yl) -5-dimethylaminophthalide, 33-bis (1,2-dimethylindol-3-yl) -6-dimethyl Aminophthalide, 3,3-bis (9
-Ethylcarbazol-3-yl) -5-dimethylaminophthalide, 3,3-bis (2-phenylindole-
3-yl) -5-dimethylaminophthalide, 3-p-dimethylaminophenyl-3- (1-methylpyrrole-2)
-Yl) -6-dimethylaminophthalide and the like.

(2) Diphenylmethane compound 4,4'-bis-dimethylaminophenylbenzhydryl benzyl ether, N-halophenyl leuco auramine, 2,4,5-trichlorophenyl leuco auramine and the like.

(3) Xanthene compound Rhodamine B anilinolactam, Rhodamine B p-chloroanilinolactam, 3-diethylamino-7-dibenzylaminofluorane, 3-diethylamino-7-octylaminofluorane, 3- Diethylamino-7-phenylfluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-6-chloro-7-methylfluorane, 3-diethylamino-7- (3,4-dichloroanilino) fluorane, 3 -Diethylamino-7
-(2-chloroanilino) fluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3- (N
-Ethyl-N-tolyl) amino-6-methyl-7-anilinofluorane, 3-piperidino-6-methyl-7-anilinofluorane, 3- (N-ethyl-N-tolyl) amino-6- Methyl-7-phenethylfluorane, 3-diethylamino-7- (4-nitroanilinofluorane,
3-dibutylamino-6-methyl-7-anilinofluorane, 3- (N-methyl-N-propyl) amino-6-
Methyl-7-anilinofluorane, 3- (N-ethyl-
N-isoamyl) amino-6-methyl-7-anilinofluorane, 3- (N-methyl-N-cyclohexyl) amino-6-methyl-7-anilinofluorane, 3- (N
-Ethyl-N-tetrahydrofuryl) amino-6-methyl-7-anilinofluorane and the like.

(4) Thiazine Compounds Benzoyl leuco methylene blue, p-nitrobenzoyl leuco methylene blue and the like.

(5) Spiro compound 3-methylspirodinaphthopyran, 3-ethylspirodinaphthopyran, 3,3'-dichlorospirodinaphthopyran, 3-benzylspirodinaphthopyran, 3-methylnaphtho- (3 -Methoxybenzo) spiropyran, 3-propylspirobenzopyran and the like. Etc. can be mentioned, and these can be used individually or in mixture of 2 or more types.

Specific examples of the electron-accepting color developer used in the present invention include phenol derivatives, aromatic carboxylic acid derivatives or metal compounds thereof, N, N'-diarylthiourea derivatives and the like. .. Of these, particularly preferred are phenol derivatives, specifically, p-phenylphenol, p-hydroxyacetophenone, 4-hydroxy-4'-methyldiphenyl sulfone, 4-hydroxy-4'-isopropoxydiphenyl. Sulfone, 4-hydroxy-4′-benzenesulfonyloxydiphenyl sulfone, 1,1-bis (p-hydroxyphenylpropane, 1,1-bis (p-hydroxyphenyl) pentane, 1,1-bis (p-hydroxyphenyl) ) Hexane, 1,1-bis (p-hydroxyphenyl) cyclohexane, 2,2-bis (p-hydroxyphenyl) propane, 2,2-bis (p-hydroxyphenyl) butane, 2,2-bis (p-). Hydroxyphenyl) hexane, 11-bis (p-hydroxyphenyl) -2 Ethylhexanoic, 2,2-bis (3-chloro-4-hydroxyphenyl) propane, 1,1-bis (p- hydroxyphenyl) -1-phenylethane, 1
3-di [2- (p-hydroxyphenyl) -2-propyl] benzene, 1,3-di [2- (3,4-dihydroxyphenyl-2-propyl] benzene, 1,4-di [2
-(P-hydroxyphenyl) -2-propyl] benzene, 4,4'-dihydroxydiphenyl ether 4,
4'-dihydroxydiphenyl sulfone, 3,3'-dichloro-4,4'-dihydroxydiphenyl sulfone,
3,3'-diallyl-4,4'-dihydroxydiphenyl sulfone, 3,3'-dichloro-4,4'-dihydroxydiphenyl sulfide, methyl 2,2-bis (4-hydroxyphenyl) acetate 2,2-bis Butyl (4-hydroxyphenyl) acetate, 4,4′-thiobis (2-t
-Butyl-5-methylphenol), bis (3-allyl-4-hydroxyphenyl) sulfone, 4-hydroxy-4'-isopropyloxydiphenyl sulfone,
3,4-Dihydroxy-4'-methyldiphenyl sulfone, p-hydroxybenzoic acid benzyl, p-hydroxybenzoic acid chlorobenzyl, p-hydroxybenzoic acid propyl, p-hydroxybenzoic acid butyl, 4-hydroxyphthalic acid dimethyl, gallic acid Examples thereof include benzyl acid salt, stearyl gallate, salicylanilide, and 5-chlorosalicylanilide, and at least one of them can be used.

Specific examples of the sensitizer used in the present invention include N-hydroxymethylstearic acid amide, stearic acid amide, palmitic acid amide, oleic acid amide, ethylene / bisstearic acid amide, and ricinoleic acid amide. , Waxes such as paraffin wax, microcrystalline wax, polyethylene wax, rice wax and carnauba wax, naphthol derivatives such as 2-benzyloxynaphthalene, biphenyl derivatives such as p-benzylbiphenyl and 4-allyloxybiphenyl, 1,2-bis (3-methylphenoxy)
Polyether compounds such as ethane, 2,2′-bis (4-methoxyphenoxy) diethyl ether, bis (4-methoxyphenyl) ether, carbonic acid such as diphenyl carbonate dibenzyl oxalate, oxalic acid di (p-fluorobenzyl) ester, etc. Examples include oxalic acid diester derivatives,
Among these, at least one kind can be used.

[Action]

The present invention provides a microcapsule wall material,
It is a continuous production method of microcapsules which uses polyvinyl alcohol and causes insolubilization of polyvinyl alcohol based on a chelate reaction between a mixed aqueous solution of polyvinyl alcohol or a derivative thereof and zirconium chloride and an alkaline aqueous solution. The microcapsule of the present invention contains an aqueous dispersion of solid particles or an aqueous solution thereof together with water, and can be continuously produced by an 8-step process. The present invention is a continuous production method of microcapsules in which a porous glass pipe is used in the emulsification step to make the particle size uniform and to form a uniform film.

[0048]

EXAMPLES The present invention will be specifically described below with reference to examples.

Example 1 In this example, microcapsules containing three components of an electron-donating colorless dye, an electron-accepting developer and a sensitizer together with water were produced. The microcapsules produced here are
It is intended to be used as a material for thermal recording paper. An aqueous dispersion liquid was prepared by pulverizing and dispersing the three components in advance as described below. 1.3 Dispersion of Components A mixture having the following composition was pulverized and dispersed by a sand mill using anionic polyvinyl alcohol until the average particle diameter became about 0.3 μm. [Liquid A] Dispersion of electron-donating colorless dye 3-dibutylamino-6-methyl-7-anilinofluorane 150 parts 10% polyvinyl alcohol aqueous solution 75 parts water 150 parts [Liquid B] Electron-accepting developer -Co-dispersion of sensitizer 200 parts of bisphenol A benzyloxynaphthalene 200 parts 10% aqueous solution of polyvinyl alcohol 200 parts water 400 parts

2. Preparation of Microcapsule Encapsulation Solution A (electron-donating colorless dye aqueous dispersion) and solution B (electron-accepting developer-sensitizer co-dispersion) pulverized and dispersed in 1 are used. Microcapsule inclusions were prepared at the following mixing ratios. This microcapsule inclusion is composed of a 40% aqueous dispersion with a solid content ratio of colorless dye / developing agent / sensitizer = 1/1/1, and contains 60% of water. 40% A liquid (electron-donating colorless dye aqueous dispersion) 75 parts 40% B liquid (electron-accepting developer-sensitizer aqueous co-dispersion liquid) 150 parts

3. Manufacturing of Microcapsules The following preparation liquids are stored in the three types of storage tanks. In the storage tank 1, the 40% aqueous dispersion of the microcapsule-encapsulated material prepared in 2 above was stored. A 10% aqueous ammonia solution was stored in the storage tank 2. In the storage tank 3, 100 parts by weight of polyvinyl alcohol having a degree of polymerization of 2000 and a degree of saponification of 95 mol% and 10 parts by weight of zirconium chloride (chemical formula ZrOCl ₂ ) as ZrO ₂ were mixed by stirring in 890 parts by weight of water. An 11% polyvinyl alcohol-zirconium chloride mixed aqueous solution that had been heated and melted was stored. Each storage tank has a tubular section 7,
Supply pumps 4, 5 and 6 for 8 and 11 are attached,
A constant flow rate is supplied by each pump.

An aqueous dispersion of 40% microcapsule-encapsulated material in the storage tank 1 was supplied to the tubular portion 7 by a supply pump 4.
g / sec, and at the same time, 10% aqueous ammonia solution in the storage tank 2 was passed through the supply tank 5 to the tubular portion 8 at 2 g / sec, and merged at the confluence point 9 to be mixed. Junction 9
The spiral tubular portion 10 was further passed through, and these two types of aqueous liquids were mixed so as to be uniform in the tube of the spiral tubular portion 10.

At the same time, the mixed aqueous solution of 11% polyvinyl alcohol-zirconium chloride in the storage tank 3 was passed through the tubular portion 11 at a rate of 18 g / sec by the supply pump 6 and introduced into the emulsification tank 12.

Then, the aqueous mixed solution is introduced into the porous glass pipe 13 having a pore size of 4 μm, and the aqueous mixed solution introduced into the porous glass pipe permeates outside the porous glass pipe under the pressure. To form emulsified particles. Ammonia in the emulsified particles, a polyvinyl alcohol-zirconium chloride mixed solution in the emulsification tank, and a polyvinyl alcohol insolubilized wall film were instantaneously formed on the surface of the emulsified particles.

The uniform emulsified particles are used as an emulsified liquid in the tubular portion 1.
5 and introduced into the inlet section 17 of the tubular reactor 16.
The tubular reactor 16 was maintained at 55 ° C. so that the microcapsule wall membrane was completely insolubilized and its outlet 18 could be used. The microcapsules could be continuously taken out from the microcapsules discharging section 20 through the entrance section 17 and the exit section 18. The manufactured microcapsules are about 1
It had a uniform particle size of 0 μm. The liquid concentration of the microcapsule dispersion was about 45%.

4. Preparation of heat-sensitive coating liquid Using the microcapsules obtained in the above 3, the following 25%
A heat-sensitive coating liquid was prepared. 45% microcapsule dispersion 1000 parts 10% polyvinyl alcohol aqueous solution 450 parts calcium carbonate 90 parts water 800 parts

5. Production of thermosensitive recording paper An air knife using a base material having a basis weight of 60 g / m ² coated with an undercoat layer having a mixing ratio of 1: 1 of hollow resin particles made of a styrene-acrylic copolymer and kaolin. The above 4 is applied to the undercoat layer side of the substrate by a coater.
The heat-sensitive coating liquid of was applied. The drying conditions were an average of 140 ° C. in the drying zone, and the coating speed was 800 m / min. Under online conditions, the microcapsules of the heat-sensitive recording layer were broken using a super calendar, the water content in the microcapsules was absorbed in the undercoat layer of the substrate, and then wound into a roll. The coating amount (dry solid content) of the heat-sensitive recording layer after the water content in the microcapsules was absorbed in the undercoat layer of the substrate was 7 g /
The coating conditions were set so as to be m ² . The water content of the thermosensitive recording paper before breaking the microcapsules was 2%, but the water content after breaking was 6%, which had the effect of curling.

6. Evaluation of Thermal Recording Paper The whiteness of the coated surface of the manufactured thermal recording paper was measured with a Macbeth RD-918 type reflection densitometer.
It was 05. From these results, when the microcapsules produced according to the present invention were used, coating could be performed at a coating speed about twice that of conventional coating conditions, leading to a significant improvement in productivity. .. Also, GIIIF
Color density was measured using an AX tester. Testing machine
Okura Denki's (TH-PMD) thermal dot head with a dot density of 8 dots / mm and a head resistance of 1300Ω was used. Head voltage 22V, energization time 1.0
Printed under the condition of ms. About the color density of the printed image,
When measured with a Macbeth RD-918 type reflection densitometer, the value was 1.28. Observation of the printed and unprinted areas on the coated surface using an optical microscope confirmed that the microcapsules were destroyed. In particular, in the printed part, the influence of the wall material due to the breakage of the microcapsules was not seen.

Example 2 In this example, microcapsules containing a sublimable disperse dye together with water were produced. The microcapsules produced here are intended to be used as an ink for inkjet recording. 1. Aqueous Dispersion of Sublimable Disperse Dye 2- (p-diethylaminophenylazo) -5-nitro-1,3-thiazole was used as a magenta sublimable disperse dye. 10 parts of a sublimable disperse dye was mixed with 90 parts of ion-exchanged water, and pulverized and dispersed using a sand mill so that the average particle diameter was 0.2 μm.

2. Production of microcapsules The prepared liquids are stored in the three types of storage tanks as follows. In the storage tank 1, an aqueous dispersion containing the 10% sublimable disperse dye of the microcapsule-encapsulated material dispersed in the above 1 was stored. A 10% aqueous ammonia solution was stored in the storage tank 2. In the storage tank 3, the same 11% polyvinyl alcohol-zirconium chloride mixed aqueous solution as in Example 1 was stored. Supply pumps 4, 5 and 6 for the tubular portions 7, 8 and 11 are attached to the respective storage tanks, and a constant flow rate is supplied by the respective pumps.

8 g of an aqueous dispersion of the 10% microcapsule-encapsulated material in the storage tank 1 was supplied to the tubular portion 7 by the supply pump 4.
/ Sec., And at the same time, 10 g of the ammonia solution in the storage tank 2 was passed by the supply tank 5 to the tubular portion 8 at 3 g / sec. The spiral tubular portion 10 was passed from the confluence point 9, and these two kinds of aqueous liquids were mixed in the pipe of the spiral tubular portion 10 so as to be uniform.

Simultaneously, the mixed aqueous solution of 11% polyvinyl alcohol / zirconium chloride in the storage tank 3 was passed through the tubular portion 11 at 20 g / sec by the supply pump 6 and introduced into the emulsification tank 12.

Then, the aqueous mixed solution is introduced into the porous glass pipe 13 having a pore system of 4 μm, and the aqueous mixed solution introduced into the porous glass pipe is permeated to the outside of the porous glass pipe under pressure. To form emulsified particles. Ammonia in the emulsified particles, a polyvinyl alcohol-zirconium chloride mixed solution in the emulsification tank, and a polyvinyl alcohol insolubilized wall film were instantaneously formed on the surface of the emulsified particles.

The uniform emulsified particles are used as an emulsified liquid in the tubular portion 1.
5 and introduced into the inlet section 17 of the tubular reactor 16.
The tubular reactor 16 was maintained at 60 ° C. so that the microcapsule wall membrane was completely insolubilized and the outlet 18 could be used. The microcapsules could be continuously taken out from the microcapsules discharging section 20 through the entrance section 17 and the exit section 18. The manufactured microcapsules are about 1
It had a uniform particle size of 0 μm. The liquid concentration of the microcapsule dispersion was about 35%.

3. Preparation of Inkjet Recording Ink An inkjet recording ink was prepared as follows using the microcapsules produced above. 35% microcapsule aqueous dispersion 100 parts ethylene glycol 20 parts

4. Printing test The inkjet recording ink prepared in the above 3 was used to print on an inkjet recording paper for evaluation. As the printing apparatus, an inkjet printer manufactured by Sharp Corporation (IO-720) was used, and solid printing was performed by changing the printing density stepwise. Pass the recording paper of the recorded printed image through the super calendar, destroy the microcapsules in the image area,
Then, printing was completed by passing through a hot roll set at 100 ° C. An image that was stepwise eliminates its border,
An image with gentle gradation was obtained.

[0067]

INDUSTRIAL APPLICABILITY The present invention includes an aqueous dispersion or aqueous solution of solid particles and water, which is introduced into a porous glass pipe to utilize the chelate reaction between a polyvinyl alcohol-zirconium chloride mixed aqueous solution and an alkaline aqueous solution. do it,
It is a microcapsule continuous production method capable of continuously producing microcapsules composed of a polyvinyl alcohol wall film. The microcapsules containing solid particles together with water, for example, when applied to a heat-sensitive recording material, lead to improved productivity and can be widely applied.

[Brief description of drawings]

FIG. 1 is a schematic view of a continuous production process of microcapsules showing an embodiment of the present invention.

FIG. 2 is a schematic view of a continuous manufacturing process of microcapsules showing an embodiment of the present invention.

FIG. 3 is a schematic view of a continuous manufacturing process of microcapsules showing one embodiment of the present invention.

[Explanation of symbols]

1 Storage Tank 2 Storage Tank 3 Storage Tank 4 Supply Pump for Storage Tank 1 5 Supply Pump for Storage Tank 2 6 Supply Pump for Storage Tank 3 7, 8, 11, 15, 19, 22, 26, 27, 28,
29 Tubular part 9 Confluence of liquid of storage tanks 1 and 2 10, 21 Tubular part or spiral tubular part 12, 23 Emulsification tank 13, 24 Porous glass pipe 14, 25 Emulsion 16 Tubular reactor 17 Tubular reactor inlet Part 18 Exit of tubular reactor 20 Discharge part of microcapsule

Claims (4)

[Claims] 1. A method for continuously producing microcapsules containing an aqueous dispersion of at least one or more solid particles or an aqueous solution thereof, wherein the inclusion of microcapsules comprises an aqueous dispersion of the solid particles or an aqueous solution thereof and water. Both of them and an aqueous alkali solution or a mixed aqueous solution of polyvinyl alcohol or its derivative and zirconium chloride. By the following steps 1 to 8, an aqueous dispersion of the solid particles or an aqueous solution thereof is obtained. A continuous production method of microcapsules, which comprises continuously producing the encapsulated microcapsules. 1) An aqueous dispersion of the solid particles or an aqueous solution thereof stored in the first storage tank and an alkaline aqueous solution or a mixed aqueous solution of polyvinyl alcohol or its derivative and zirconium chloride stored in the second storage tank are kept constant, respectively. A step of forming a mixed state by supplying at a flow rate into the tubular portion and mixing at the confluence. 2) In the tubular part or the spiral tubular part connected to the confluence,
A step of continuously passing the mixed liquid at a constant flow rate to introduce the mixed liquid into a porous glass pipe. 3) Simultaneously with the above 2), a step of supplying a mixed aqueous solution of polyvinyl alcohol or its derivative and zirconium chloride or an alkaline aqueous solution stored in a third storage tank into the tubular portion at a constant flow rate and introducing the same into the emulsification tank. 4) A step of allowing the microcapsule inclusions to permeate the porous glass pipe having fine pores under pressure to form emulsified particles in the emulsification tank. 5) A step of pre-coating the surface of the emulsified particles with polyvinyl alcohol. 6) A step of introducing an emulsion of pre-coated emulsion particles into the tubular portion. 7) A step of continuously passing the emulsion through a tubular reactor maintained at a constant temperature. 8) A step of passing through the tubular reactor to the tubular portion and taking out the formed microcapsules from the discharge portion. 2. The microparticle according to claim 1, wherein the solid particles are one or more kinds selected from the group consisting of an electron-donating colorless dye, an electron-accepting developer and a sensitizer. Continuous capsule manufacturing method. 3. The continuous production method of microcapsules according to claim 1, wherein the temperature is 30 to 90 ° C. in a tubular reactor maintained at a constant temperature. 4. The porous glass pipe is 0.2-100.
The method for continuously producing microcapsules according to claim 1, 2 or 3, wherein the microcapsules have a pore size of μm.