JPS62234541A - Production of colored microcapsule - Google Patents

Abstract

PURPOSE:To improve the ageing stability of the title microcapsule by forming a colored microcapsule contg. an oil phase wherein a hydrophilic inorg. pigment is dispersed, and facilitating the capsulation of the inorg. pigment. CONSTITUTION:An inorg. pigment such as an org. pigment of red iron oxide, etc., a white pigment of titanium oxide, etc., and a pearl pigment of mica, etc., is made hydrophilic by coating, etc., with silicone oil, resins, metallic soap, etc. The hydrophilic org. pigment is dispersed in an oil such as safflower oil and carnauba wax to prepare an oil phase having 20-1,000cp (25 deg.C) viscosity. The oil phase is microcapsulated by a public-known means such as interfacial polymerization, a submerged curing and coating method, phase separation from a water or org. soln. system, etc. A vinyl monomer, an acrylic monomer, a styrene monomer, etc., are exemplified as the component of the capsulating film.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for producing colored microcapsules, particularly microcapsules characterized by encapsulating an oil phase in which a lipophilized inorganic pigment is dispersed.

(Prior art and its problems) Conventionally, colored microcapsules are known to be made by adsorbing a dye onto the membrane surface or by forming the membrane itself with a dye. However, since these microcapsules are limited in the types of pigments that can be adsorbed onto the surface and the dyes that form the membrane material, there is a problem that colors cannot be produced freely, and furthermore, the coloring power is insufficient. Furthermore, when such microcapsules are used as a coloring material, there are also problems in stability over time such as weather resistance.

There is also the problem that if the capsule is destroyed during use, a decrease in saturation and brightness and a shift in hue occur.

An object of the present invention is to overcome the above-mentioned problems associated with single-colored microcapsules, and to provide colored microcapsules that can be colored in any color and have excellent stability over time.

(Means for Solving Problems According to the Invention) The objects of the present invention as described above are achieved by microcapsules characterized by encapsulating an oil phase in which a lipophilized inorganic pigment is dispersed.

(Embodiment modes and effects) Examples of inorganic pigments that can be applied to the present invention include red iron, chromium hydroxide, red lead 2 ultramarine, deep blue, cobalt hydroxide, yellow lead,
Colored pigments such as chromium oxide, iron oxide yellow, and iron oxide black, white pigments such as titanium oxide, zinc white, lead white, basic lead sulfate, lead sulfate, lithopone, zinc sulfide, and antimony oxide, and fish scale foil.

Burr pigments such as bismuth oxychloride, titanium mica, and mica, pallite powder, and precipitated barium sulfate.

Examples of extender pigments include barium carbonate, lime carbonate powder, precipitated calcium carbonate, gypsum, asbestos, clay, silica powder, finely divided silicic acid, diatomaceous earth, talc, basic magnesium carbonate, alumina white, gloss white, and satin white. .

Since all of these inorganic pigments are oleophobic, it is difficult to microencapsulate them using organic compounds such as resins.
Even if it is encapsulated, the oil oozes out, making it difficult to use. Accordingly, in the present invention, these inorganic pigments are made lipophilic and then dispersed in oil to form microcapsules.

Silicone oil,
Known methods such as coating with resin, metal soap, etc., alkylation with alkoxysilane, etc. can be applied, but if the pigment is not sufficiently lipophilized, successful microencapsulation may not be possible. That is, in order to microcapsule a lipophilized pigment by dispersing it in oil, the degree of lipophilization (L) defined in Example 1 must be 0.95 or more, more preferably 0.98 or more.

The oil for dispersing the lipophilic pigment is not particularly limited and can be selected depending on the purpose of use of the colored capsule, but examples include oils and fats such as safflower oil, cottonseed oil, and palm oil, and carnauba wax. , Candelilla Row,
Examples include waxes such as lanolin, hydrocarbons such as liquid paraffin, vaseline, and paraffin, esters such as isopropyl myristate and dioctyl sebacate, and silicone oils such as polydimethylsiloxane and polymethylphenylsiloxane.

The method and ratio of dispersing the lipophilic pigment in the oil phase are not particularly limited, but care must be taken because if the content is high, the viscosity will increase and the oil phase will not be able to be finely divided. In the present invention, when the pigment is dispersed, the viscosity of the oil phase is 3.
If the temperature exceeded 000cP (at 25°C), microencapsulation could not be achieved successfully. Preferably, the viscosity of the oil phase is 20 to 1000 cP (at 25°C).

In the present invention, the method for producing colored microcapsules is not particularly limited, and known microcapsule production methods such as interfacial polymerization method, in-liquid hardening coating method, phase separation method from water or organic solution system, and air suspension coating method are used. Techniques can be applied, particularly those described in Japanese Patent Application Laid-open No. Sho Go-824. in 5 using colloidal silica or montmorillonite inorganic suspension agents.
The Itu polymerization method is applied.

Examples of the components constituting the capsule membrane include vinyl monomers such as vinyl chloride, acrylonitrile, vinyl acetate, and methyl vinyl ether; acrylic monomers such as acrylic acid and ethyl acrylate; methacrylic acid monomers such as methyl methacrylate; Examples include styrenic monomers such as styrene and α-methylstyrene, as well as vinylidene chloride, divinylbenzene, and ethylene glycol dimethacrylate.1 Monomers that are essentially hydrophobic and have transparency when polymerized For example, the monomers are not limited to the above monomers, and these monomers can be used alone or in combination of two or more. In order to fully bring out the color of the pigment dispersed in the oil phase inside the capsule, 7o'f of highly transparent methyl methacrylate is added.
It was preferable to use a monomer containing f1f16 or more.

The method for producing colored (colorant-containing) microcapsules of the present invention will be explained below by giving specific examples.

(Example) Example 1 Inorganic pigments were made lipophilic by the method shown below to obtain four types of lipophilic pigments.

(Production Example 1) 80 g of ultramarine blue was dispersed in water containing 1 g of aluminum sulfate (dihydrate) to make the total amount 800 mJ.

It was heated to 60°C. 6.8g of sodium stearate toO+j! of water was added and dissolved at 70°C.
The temperature was adjusted to ℃. This was gradually added to the previous ultramarine blue slurry to precipitate aluminum stearate on the surface of the second ultramarine blue to make it lipophilic. 10 days after addition of metal soap
After a few minutes have elapsed, stirring of the system is stopped and the total volume of slurry is 3000 mf! 60°C hot water was added until the temperature reached 60°C, and the mixture was allowed to stand still. After the pigment had settled, it was decanted, hot water at 60°C was added again, and the mixture was allowed to stand still. After the completion of the 24th decantation, the pigment was suction filtered, dried, and crushed to obtain the desired lipophilized ultramarine blue product.

(Production Example 2) Disperse 80g of iron oxide in hot water at 60°C in which 6.8g of sodium stearate has been dissolved.
Set to 0m J. 100a+j for this! 6 g of aluminum sulfate (dihydrate) dissolved in water was gradually added to make it lipophilic. The subsequent operations were carried out in the same manner as in Production Example 1 to obtain a lipophilized product of iron oxide.

(Comparative Example 1) Manufacturing Example 1 except that sodium stearate was changed to 3.4 g. Lipophilization was carried out by the method described above to obtain a lipophilized product of Ultramarine Blue.

(Comparative example 2) Manufacturing example 2 except that aluminum sulfate (12 hydrate) was changed to 3 g. Lipophilization was carried out using the method described above, and a lipophilized product of iron oxide was obtained.

The degree of lipophilization (L) of these four types of lipophilized pigments was evaluated by the method shown below, and it was determined whether or not they were suitable for microencapsulation.

(Method for Measuring the Degree of Lipophilization) 1 g of the lipophilized pigment was dispersed in liquid paraffin at 5011° C. using a disper at 0.000 rpm for 1 minute. Put this into a 100ffli separating funnel and
After adding distilled water at ℃, the mixture was vigorously shaken up and down with two hands 100 times. After standing for 30 minutes, the aqueous phase was collected and evaporated to dryness to determine the weight of the pigment dispersed in the aqueous phase (W + unit g).
) was sought. The degree of lipophilicity (L) of the pigment was defined as L12-w.

In order to disperse the lipophilic pigment in oil and microcapsule it, L should be 0.95 or more, more preferably 0.98.
It was necessary to do more than that. Table 1 shows the degree of lipophilicity of each pigment, including commercially available pigments, and the success or failure of microencapsulation. Microencapsulation was carried out in the same manner as in Example 2 below.

(Margin below) Table 1 Method for producing lipophilic pigment No. 6 Dissolve 7 g of squalane in 100 Ilz of hexane.

Add 100g of yellow iron oxide to this, mix and disperse with a stirrer for 1 hour, and then use a rotary evaporator to remove 50g of yellow iron oxide.
Hexane was distilled off at °C to obtain the desired lipophilic pigment.

Method for producing lipophilic pigment No. 7 Dissolve 5g of Span 80 in 150g of chloroform.

100 g of yellow iron oxide was added to this, and the desired lipophilic pigment was obtained in the same manner as No. 6.

Example 2 (Parts by weight) A
was treated with a disper at 700 rpm for 3 minutes to disperse the lipophilized titanium oxide, and then pre-dissolved B was added and mixed uniformly. C and D separately dispersed and dissolved
Mix and coarsely emulsify by adding A and B, then emulsify in a homomixer at 1000 rpa+ for 1 minute.

Dispersion was performed. Transfer this suspension to a reactor equipped with a reflux condenser, stirrer, thermometer, and nitrogen inlet tube.

A polymerization reaction was carried out at 65° C. for 6 hours to produce microcapsules. The slurry in which the microcapsules were dispersed was filtered, washed, and dried to obtain the desired colored microcapsules (white).

Example 3 (Parts by weight) A
After melting at 80° C., roughly mixed B is added and dispersed using a disper at 7000 rpm for 3 minutes to form a paste, and pre-dissolved C is added to this to form an oil phase. Disperse or dissolve separately.

After mixing E and adding an oil phase to roughly emulsify, emulsification 1 dispersion was performed using a homomixer at 11,000 rpm for 1 minute. This suspension was heated at 65°C in the same apparatus as in Example 2.
A polymerization reaction was carried out for 6 hours to produce microcapsules. The slurry was treated in the same manner as in Example 2 to obtain the desired powder colored microcapsules (skin color).

Example 4 (fIrf
fi part) A at 7000 rpm with a disperser, 3
After processing for a minute to disperse Aerosil R972, pre-dissolved B is added and mixed uniformly. Hydrochloric acid was added to the transparently dispersed C to adjust the pH to 3.5, and an oil phase was added to coarsely emulsify it.
Emulsification and dispersion were performed for 1 minute. This suspension was subjected to a polymerization reaction at 65° C. for 6 hours in the same apparatus as in Example 2 to produce microcapsules. The slurry was treated in the same manner as in Example 2 to obtain the desired powder colored capsules.

(Effects of the Invention) As described above, according to the method of the present invention, colored microcapsules having any color and excellent stability over time can be obtained by encapsulating an inorganic pigment in a container. The colored microcapsules of the present invention can be widely applied to industries, cosmetics, food, and more.

It can be used for pharmaceuticals, printing, toner, etc.

Applicant: POLA CHEMICAL INDUSTRIES, INC. Agent: Patent Attorney Asami Kafuji (1 other person)

Claims (1)

[Claims] A method for producing microcapsules characterized by encapsulating an oil phase in which a lipophilized inorganic pigment is dispersed.