JP2679233B2 - Method for manufacturing capsule body - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Purpose of the invention [Industrial field of application] The present invention relates to a method for producing a capsule body having a film-forming polymer as a wall film, and particularly to It is intended to provide a method for industrially extremely advantageously producing high capsules.

The capsule body obtained by the present invention can be used for the following purposes.

For example, the capsule body having water as a core substance obtained in the present invention is used as a humidity control agent for enhancing the texture of the inner surface of the fiber, and the capsule body having a non-combustible agent containing water as a core substance is not contained in the building material board. In the case of a fire or the like, it can be used as a so-called heat-resistant building material board, in which the capsule body is destroyed and the contents are evaporated to take heat.

Furthermore, the capsule body having the aqueous ink as a core substance obtained in the present invention is broken by freezing, so that even if the frozen food after freezing is thawed even once, it is thawed by the color display by the exudation of the ink. Can be used as a so-called thawing history display indicator for frozen foods, or as an aroma-imparting agent that does not emit a fragrance during freezing by containing an aqueous fragrance agent instead of an aqueous ink and releases an aroma to the surroundings after thawing.

Furthermore, the capsule body obtained by the present invention containing glycerin, a finely powdered carbohydrate, or a derivative thereof as a core substance can be used as a moisture-retaining cosmetic product or an oxygen scavenger.

[Conventional technology]

Conventionally, as a technique for encapsulating microdroplets of an aqueous liquid, an aqueous liquid as a core substance is directly suspended in a solution composed of a hydrophobic solvent and a film-forming polymer, and the resulting suspension is treated with water. It is dispersed in a medium in the form of microdroplets, and then the dispersion is heated under reduced pressure, if necessary, to a temperature not lower than the boiling point of the hydrophobic solvent, or by blowing a gas insoluble in the dispersion, A so-called in-water drying method for removing the organic solvent is known.

[Problems to be solved by the invention]

However, in order to produce a capsule body containing a core substance at a high content rate, the initial evaporation rate of the hydrophobic solvent must be high, but this method constantly forms a film of the film-forming polymer on the liquid surface. In addition, it becomes difficult to evaporate the solvent, and due to the evaporation of the solvent, the volume of the entire dispersion liquid charged is reduced and the stirring state cannot be kept constant, which makes it difficult to form a capsule body having a uniform particle size. It had drawbacks.

Furthermore, this method also has the drawback that foaming occurs during evaporation of the hydrophobic solvent, making it difficult to uniformly stir in the upper part of the evaporation tank, producing aggregated capsule bodies, and lowering the yield of capsule bodies. It was

These phenomena are particularly remarkable when the evaporation tank is scaled up, which is the cause of the method not being industrially used.

(B) Configuration of the Invention [Means for Solving the Problems] In order to solve the above problems, the present inventors have made diligent studies, and as a result, by spraying water on the evaporation surface of the hydrophobic solvent,
The inventors have found that all the above problems can be solved, and have completed the present invention.

That is, the present invention is to suspend a substance to be a core substance in a hydrophobic solution prepared by dissolving a film-forming polymer in a hydrophobic solvent, and to obtain a suspension containing water or a medium containing water as a main component. In the dispersion liquid, by forming a hydrophobic solution microparticles encapsulating the core substance by dispersing it in the form of microdroplets, and then performing heating operation and / or gas blowing operation under normal pressure or reduced pressure, Producing a capsule body containing the core substance by forming the film-forming polymer wall film around the core substance by removing the hydrophobic solvent from the hydrophobic solution layer of the fine particles. In the method described above, water is sprayed on the liquid surface when the hydrophobic solvent is removed.

 Hereinafter, the present invention will be described in detail in the order of steps.

(1) Hydrophobic solvent prepared by dissolving the film-forming polymer in a hydrophobic solvent: The film-forming polymer and the hydrophobic solvent are charged into a mixing tank and stirred at room temperature or under heating to form a solution. .

Since the film-forming polymer needs to be dissolved in a hydrophobic solvent to form a uniform solution composition, both are selected as a pair with each other.

For example, for chlorine-based solvents such as methylene chloride, vinylidene chloride, methyl chloroform or vinyl chloride,
Polystyrene; Copolymer with styrene and acrylic acid, acrylic acid ester, methacrylic acid, methacrylic acid ester, butadiene or acrylonitrile; Low molecular weight polyethylene; Chlorinated rubber; Low molecular weight vinylidene chloride and vinyl chloride copolymers; Methyl methacrylate resin;
A polyester or a nylon copolymer having a low crystallinity can be used.

For aromatic hydrocarbons such as benzene, toluene, and xylene, the above-mentioned polymers except those having low crystallinity polyester and nylon copolymer are used.

Ethyl acetate, n-propyl acetate, isopropyl acetate,
For fatty acid esters such as methyl propionate, ethyl propionate or methyl butyrate, nitrocellulose, ethyl cellulose ester gum, coumarone resin, rosin and the like are preferably used.

Among these, a combination of methylene chloride or vinylidene chloride and a polystyrene resin or a methyl methacrylate resin; a combination of benzene and ethyl cellulose is preferable because of good compatibility.

The mixing ratio of the hydrophobic solvent and the film-forming polymer is
Film-forming polymer 1 to 1 per 100 parts by weight of hydrophobic solvent
0 parts by weight is preferred.

If it is less than 1 part by weight, the film of the formed capsule body is too thin and is easily broken, and if it exceeds 10 parts by weight, the film obtained is too thick and the viscosity of the suspension obtained in the next step is too high, which is not preferable.

The hydrophobic solvent is preferably used in an amount of 70 to 300 parts by weight with respect to 100 parts by weight of the substance to be encapsulated, but in this mixing ratio, it is substantially incompatible with the substance to be encapsulated, that is, uniform. It is necessary not to form a single phase.

The boiling point of the hydrophobic solvent is not particularly limited because it is expected to be azeotropic with water, but it is preferably in the range of 30 to 100 ° C. because the solvent can be easily removed.

(2) Step of suspending the substance to be the core substance in the hydrophobic solution of (1): If the substance to be the core substance is added to the hydrophobic solution of (1) and sufficiently mixed under high stirring, A suspension can be obtained.

In this case, if a small amount of an aqueous solution of an oil-soluble surfactant or a hydrophilic suspending agent is previously present in the solution, a stable suspension can be obtained more easily, but if a large amount is used, a hydrophobic solvent is used. In the step of evaporating, the foaming becomes remarkable, which is not preferable.

The substance used as the core substance is water, an aqueous solution, an aqueous dispersion, a gel-like substance or a fine powdery substance selected according to the use, and for example, pure water, an incombustible agent containing water, an aqueous ink solution, an aromatic water solution. , A mixed solution of glycerin and water, an enzyme aqueous solution, cosmetics, finely powdered carbohydrates or L-ascorbic acid.

(3) A step of dispersing the suspension obtained in (2) in the form of microdroplets in water or a water-based medium: a pressure exceeding the vapor pressure of the hydrophobic solvent in the suspension obtained in (2). Below, a microdroplet generator, for example, an atomizer of the centrifugal spraying type, can be used to directly make microdroplets, but in order to obtain a more uniform particle size, the suspension is water or water-based. It is preferable to disperse the medium in the medium under relatively strong stirring.

At this time, if a dispersant such as gelatin, partially saponified polyvinyl alcohol or styrene-maleic anhydride copolymer is previously dissolved in the medium, the suspension can be easily dispersed in the form of microdroplets. it can.

By this step, fine particles containing the core substance and having the hydrophobic solution as the wall layer are formed.

(4) Removal of Hydrophobic Solvent: From the hydrophobic solution of fine particles in the dispersion liquid, by heating the dispersion liquid obtained above under normal pressure or reduced pressure and / or blowing an insoluble gas into the medium. The hydrophobic solvent is removed from the resulting wall layer.

At this time, the present invention is characterized in that water is sprinkled on the evaporation surface.

An apparatus suitable for this operation will be described in detail with reference to the accompanying drawings.

Reference numeral 1 in FIG. 1 denotes an evaporation tank having an open upper portion and an agitator 2 attached thereto, and a jacket 5 for heating is attached as necessary.

The dispersion obtained through the steps (1) to (3) is charged in the tank. .

Reference numeral 3 is a ring-shaped water sprinkler having a large number of fine nozzles, and is provided with a pressurization type water storage tank 4.

Water can be sprayed in the form of fine droplets from the nozzle onto the liquid surface of the dispersion liquid.

If the water sprinkling rate is set to the same level as the evaporation rate of the hydrophobic solvent that evaporates from the dispersion, and the water sprinkling amount is set to the same level as the amount of the hydrophobic solvent that finally evaporates, the amount of the dispersion is always approximately It is preferable because it becomes constant and the stirring state is always kept constant.

As a method for keeping the amount of the dispersion liquid constant, water may be supplied to the evaporation tank by another method other than the adjustment of the amount of water sprayed.

It is preferable that the water sprinkling is performed during the initial period when the evaporation of the hydrophobic solvent is remarkable, because the yield of the capsule is good.

By this step, a capsule body coated with a polymer wall film containing no solvent can be obtained in the form of a slurry, and is further dehydrated by a vacuum filter or a centrifuge to be recovered as a cake.

The obtained capsule body can be used as it is by mixing it with other substances, but if necessary, it can be used after drying the surface of the capsule body through an airflow dryer or a fluid dryer.

The amount of the inclusions in the obtained capsule body is preferably 20 to 90 when the weight of the entire capsule body is 100.

When it exceeds 90, the film thickness is too thin and the capsule is easily broken, and when it is less than 20, the film is too thick and the performance as a capsule body is not sufficiently exhibited, which is not preferable.

[Action]

In the present invention, when the hydrophobic solvent is removed by evaporation, water can be sprayed on the evaporation surface to produce a capsule body with a high yield.

The reason for this is that the film formation polymer film is prevented from being formed on the liquid surface by water sprinkling, so that the removal rate of the hydrophobic solvent is increased and the film formation rate around the capsule body is increased, resulting in inclusion. It is considered that this can prevent the substance from flowing out of the capsule body from the inside.

Further, the particle size distribution width of the capsule body obtained in the present invention is narrow, which is considered to be because the stirring is sufficiently controlled because the foaming is small and the liquid amount is constant.

(Examples and Comparative Examples)

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.

The particle size distribution is measured using a wet sieving method,
The weight of the mesh non-passing material (abbreviated as “non-particulate matter” in Table 1) was measured, and then the weight% of the passing material that did not pass through the 100 mesh sieve (“100 M in Table 1”).
"above". ) And the weight percentage of those passing through a 280 mesh sieve (abbreviated as “under 280 Me” in Table 1) were measured.

Example 1 On the upper part of a mixing tank having an inner volume of 100 and an inner diameter of 50 cm and an open upper surface, an inner diameter of 10 cm and an outer diameter of 45 cm were obtained, with an average of 20 diameters per cm ² .
An apparatus having an embodiment shown in FIG. 1 having a ring-shaped water sprinkler having a nozzle hole of 5 mm and having a paddle type stirrer and a nozzle for blowing nitrogen was used.

Stylon 679 (polystyrene polymer having a number average molecular weight of 100,000; manufactured by Asahi Chemical Industry Co., Ltd.) 550 g and methylene chloride
A solution consisting of 15.8 kg was charged and pure water was added under stirring at 250 rpm.
1.3 kg was charged and stirred for 2 minutes.

Then, stirring was set to 200 rpm, 45 kg of an aqueous solution in which 450 g of gelatin was dissolved was charged, and the temperature of the liquid was heated from 18 ° C to 45 ° C, and at the same time, stirring was performed for 20 minutes while water was sprinkling on the liquid surface at a flow rate of 1.0 kg / min. Further, the sprinkling of water was stopped and stirring was continued at 45 ° C. for 1 hour to obtain a slurry.

After filtering this with a vacuum filter, it was passed through an air dryer for 2 hours to obtain a capsule body containing water, and the particle size distribution was measured according to the method described above. The results are shown in Table 1.

Examples 2 to 8, Comparative Example 1 Other than changing the types and amounts of the hydrophobic solvent, the film-forming polymer and the inclusions, the amount and period of water spray, and the temperature in the solvent removal step in Example 1 as shown in Table 1. Is Example 1
Under the same conditions as above, a capsule body was obtained.

 Table 1 shows the evaluation results of the obtained capsules.

(C) Effect of the Invention According to the method of the present invention, it becomes possible to obtain a capsule body by an in-water drying method with a high yield and a narrow particle size distribution.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view of an apparatus suitable for the present invention. 1 ... Evaporating tank, 2 ... Stirrer, 3 ... Ring sprinkler, 4 ... Pressurized water storage tank, 5 ... Jacket

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location A62C 2/00 A62C 2/00 X G01N 25/00 G01N 25/00 Z 33/02 33/02

Claims (1)

(57) [Claims] 1. A substance which becomes a core substance is suspended in a hydrophobic solution obtained by dissolving a film-forming polymer in a hydrophobic solvent, and the resulting suspension is water or a medium containing water as a main component. In the dispersion liquid, by forming a hydrophobic solution microparticles encapsulating the core substance by dispersing it in the form of microdroplets, and then performing heating operation and / or gas blowing operation under normal pressure or reduced pressure, Producing a capsule body containing the core substance by forming the film-forming polymer wall film around the core substance by removing the hydrophobic solvent from the hydrophobic solution layer of the fine particles. The method for producing a capsule body according to the above method, wherein water is sprayed on the liquid surface when the hydrophobic solvent is removed.