JPH0416212B2 - - Google Patents

Description

[Detailed description of the invention]

TECHNICAL FIELD The present invention relates to oil-containing mineral walled microcapsules. The microcapsules of the present invention have a unique effect in that the oil or oily solution encapsulated in the hollow part of the porous inorganic wall is released in a sustained manner.
It is useful as a holding material for active ingredients in pharmaceuticals, cosmetics, fragrances, etc. Structure of the Invention The oil-containing microcapsule of the present invention is a novel structure that has not been described in any literature. The oil-containing microcapsules of the present invention are spheres having an inorganic wall with a seamless structure surrounding an oil or an oily solution having a solubility in water of 5% or less, and have a diameter of
It has a size of about 0.1 to 50 μm. The inorganic wall material is porous and has a large number of minute pores that do not allow the contained oil or oily solution to freely flow out, but allow slow seepage over a long period of time under certain conditions. Therefore, the microcapsules of the present invention exhibit the following protective function and the function of changing the shape and properties of the contained substances. Protective function (1) Can suppress volatilization of volatile substances. (2) Two or more substances that have high reactivity with each other,
Alternatively, by separately encapsulating two or more immiscible substances in microcapsules, it becomes possible to appropriately mix and react them as necessary. (3) Be able to handle toxic substances safely. (4) Taste, smell, etc. can be hidden. (5) The effects of light, oxygen, heat, moisture, etc. can be eliminated. Change function (1) It is possible to solidify liquid substances. (2) It is possible to solidify oil-soluble gaseous substances. (3) It is possible to change the texture of inclusions and hide their color. (4) The apparent solubility of inclusions can be changed. (5) The apparent specific gravity of inclusions can be changed. (6) By adjusting the type, thickness, and degree of porosity of the wall material, the release conditions of inclusions can be controlled. The inorganic wall of the microcapsule of the present invention is made of the following materials. Silicates of alkaline earth metals...magnesium silicate, calcium silicate, strontium silicate, barium silicate, etc. Alkaline earth metal oxides...magnesium oxide, barium oxide, calcium oxide, strontium oxide, etc. Carbonates and sulfates of alkaline earth metals...magnesium carbonate, calcium carbonate, strontium carbonate, barium carbonate, magnesium sulfate, calcium sulfate, strontium sulfate, barium sulfate, etc. Manganese oxides and carbonates...manganese oxide, manganese carbonate. Oxides, carbonates and hydroxides of iron, cobalt or nickel...iron oxide, hydrated iron oxide, cobalt oxide, cobalt carbonate, nickel oxide, nickel carbonate, nickel hydroxide, etc. Others...Silica (anhydrous silicic acid), calcium tungstate, basic copper carbonate, cadmium sulfide, zinc sulfide, silver sulfide, lead sulfide, silver carbonate, aluminum hydroxide, titanium oxide, zirconium hydroxide, tin oxide, hydroxide A wide variety of substances can be used as long as they are substances such as lead that are produced as water-insoluble precipitates in an aqueous reaction and do not react with the encapsulated substances. As the oil to be encapsulated in the microcapsules (referred to as an encapsulating substance), an oil having a solubility in water of 5% or less or an oily solution using the oil as a solvent is used. Such oils include natural and synthetic oils, fats and waxes such as almond oil, olive oil, spermaceti, hydrogenated oil, sesame oil, cholesterol, safflower oil, silicone, soybean oil, camellia oil, vitamin A oil, Examples include castor oil, beeswax, mink oil, cottonseed oil, Japanese wax, lanolin, liquid lanolin, vaseline, kerosene, linseed oil, oleyl alcohol, isopropyl myristate, isopropyl palmitate, etc. In addition to these oils, vitamin A, vitamin D. Oil-based solutions in which oil-soluble substances such as fragrances, menthol oil, photosensitizers, dyes, and natural pigments are dissolved are also used as inclusion substances. The oil-containing inorganic wall microcapsules of the present invention are produced, for example, as follows. First, an emulsifier in an amount of about 1 to 10% of the weight of the encapsulated substance is dissolved in the encapsulated substance made of the above-mentioned oil or oily solution. As the emulsifier, nonionic surfactants with HLB in the range of 8 to 18 are preferred, such as sorbitan monolaurate (HLB = 8.6) and polyoxyethylene sorbitan monostearate (HLB =
9.6) Polyoxyethylene sorbitan monooleate (HLB=15.0), polyoxyethylene sorbitan monolaurate (HLB=13.3), polyoxyethylene oxypropylene stearate (HLB=
15.7) etc. are exemplified as representative examples. On the other hand, silicates, carbonates, sulfates, tungstates and halides of alkali metals: sulfates, halides and nitrates of manganese; sulfates, halides and nitrates of iron, cobalt or nickel; and alkaline earth metals. Concentration containing at least one water-soluble inorganic compound (hereinafter referred to as "compound") selected from the group consisting of halides of
An aqueous solution having a saturation concentration of about 0.3 mol/~, preferably about 0.5-3.0 mol/ is prepared, and this is mixed with the emulsifier oil solution to prepare an O/W emulsion. At this time, the mixing ratio of the aqueous solution of the compound and the oily emulsifier solution is not particularly limited as long as the resulting emulsion is O/W type, but it is usually about 100 to 500 parts by weight of the latter to 100 parts by weight of the former. It is preferable that Next, an organic solvent having a solubility in water of 5% or less is added to the O/W emulsion and mixed to form an O/W emulsion.
Prepare a W/O emulsion. Examples of organic solvents with solubility in water of 5% or less include aliphatic saturated hydrocarbons such as hexane, decane, hexadecane, isohexane, and isoheptane; hexene, octene,
Aliphatic unsaturated hydrocarbons such as dimethylptadiene and heptyne; aromatic hydrocarbons such as benzene, toluene, dodecylbenzene, cymene, and styrene; alicyclic hydrocarbons such as cyclohexane, cyclohexene, and cyclononane; are used alone or in combination of two or more. Further, there is no problem even if these organic solvents contain alcohols or the like, usually up to about 10% by weight. The amount of organic solvent used is not particularly limited as long as the resulting emulsion is O/W/O type, but it is usually 50% by weight of the emulsion.
The above content is preferably 70 to 80% by weight.
The emulsification method can be done by following the usual method, such as the usual stirring method,
A shaking method etc. can be adopted. During emulsification, a known emulsifier can be added, although it is not particularly necessary. As an emulsifier, preferably HLB is 1.8
Nonionic surfactants within the range of ~8.6 can be used. Typically, sorbitan triolate (HLB=1.8), sorbitan monooleate (HLB=
4.3), sorbitan monostearate (HLB=
4.7), sorbitan monopalmitate (HLB=
6.7), sorbitan monolaurate (HLB=8.6)
, or a mixture of two or more of them, and also mixtures of two or more of various nonionic surfactants having various HLB values and adjusting the HLB to 1.8 to 8.6. Also good. These emulsifiers are
Usually, it can be used in an amount of 5.0% by weight or less, preferably 0.01 to 3.0% by weight, based on the organic solvent. Next, a compound selected from the group consisting of alkaline earth metal halides and nitrates; alkali metal carbonates, nitrates, sulfates, and halides; inorganic acids and their ammonium salts; and inorganic bases; Contains at least one compound (hereinafter referred to as "compound") that can form a water-insoluble precipitate through an aqueous reaction with
Concentration of mol/more preferably 0.1 to 2.0 mol/
Prepare an aqueous solution with a concentration of about
Mix with W/O type emulsion. The mixing ratio of the aqueous solution of the compound and the O/W/O type emulsion is 100% of the latter.
100 parts by weight or more of the former, preferably 300 parts by weight
The amount is preferably about 500 parts by weight. Oil-containing inorganic-walled microcapsules are thus formed as a reaction product, which can be filtered, washed with water and dried in a conventional manner to obtain the desired product. Effects of the Invention According to the present invention, in addition to the above-mentioned general effects shown as the protection function and the changing function, the following remarkable specific effects can be achieved in each field. (b) In the field of pharmaceuticals, by appropriately selecting the wall material, it is possible to dissolve the wall material in the body and exert a synergistic effect with the pharmaceutical ingredients in the encapsulated substance. For example, when the wall material is made of magnesium oxide, it is effective as an antacid, when it is made of calcium carbonate, it is effective as a calcium agent, and when it is made of iron oxide, it is effective as a blood thickening agent. (b) When producing microcapsules whose walls are made of polymeric substances, formaldehyde is used as a hardening agent during wall formation, so the microcapsules
Its use in fields such as pharmaceuticals, cosmetics, and food is severely restricted. However, the microcapsules of the present invention have no such restrictions at all. (c) Since the reaction proceeds in a steady state without requiring high temperature or pressure during microcapsule production,
Less energy usage. Examples Examples will be shown below to further clarify the features of the present invention. Example 1 Linseed oil solution dissolving 2% by weight of polyoxyethylene sorbitan monooleate (HLB=15.0)
4 mol of sodium silicate/100 ml of solution was added to 50 g and mixed with stirring to prepare an O/W emulsion. Then sorbitan monostearate (HLB
= 4.7) and polyoxyethylene sorbitan monooleate (HLB = 15.0) in a 1:2 mixture (weight ratio)
Add the above O/W type emulsion to 500 ml of a benzene solution containing 3% by weight of
A W/O emulsion was obtained. Then, 1.5 mol/aqueous solution of calcium chloride
The above O/W/O type emulsion was added to 1000 ml with stirring and allowed to react. After the reaction was completed, 105 g of pale yellow calcium silicate wall microcapsules containing linseed oil were obtained by filtering, washing with water, and drying at room temperature for 24 hours. The average particle size of the obtained microcapsules is
It was 9.9 μm, and the presence of linseed oil was confirmed by infrared absorption spectrum. Moreover, the content of linseed oil was 43% by weight. Example 2 1.5 mol/aqueous solution of strontium chloride instead of 1000 ml of 1.5 mol/aqueous solution of calcium chloride
The same operation as in Example 1 was performed except that 1000 ml was used to obtain linseed oil-containing strontium silicate wall microcapsule spheres having an average particle size of 10.1 μm. Example 3 Potassium carbonate aqueous solution (3 mol/) was added to 50 g of a liquid lanolin solution in which 6% by weight of polyoxyethylene sorbitan monostearate (HLB = 9.6) was dissolved.
Add 100ml and apply ultrasonic waves for 1 minute to achieve uniform O/
A W-type emulsion was obtained. Then sorbitan monostearate (HLB
400ml of benzene solution dissolving 0.1% by weight of =4.7)
Add the above O/W type emulsion to the O/W emulsion and shake.
A W/O emulsion was obtained. Next, 0.2mol/aqueous solution of calcium chloride
The above O/W/O type emulsion was added to 1800 ml under stirring and allowed to react. After the reaction is complete, the product is separated, washed with water, and kept at room temperature.
By drying for 24 hours, 81 g of spherical calcium carbonate-walled microcapsules containing lanolin were obtained. The average particle size of the obtained microcapsules is
5.5 μm, and the lanolin content was 59% by weight. Example 4 Sorbitan monolaurate (HLB=8.6)
30 g of camellia oil dissolved in weight percent was added to 100 ml of an aqueous sodium silicate solution (4 mol/concentration as SiO ₂ ), and a homogeneous O/W emulsion was prepared using a homogenizer. Then sorbitan monooleate (HLB=
Add the above O/W type emulsion to 300 ml of the hexane solution (21 g/) of 4.3), shake for 5 minutes, and remove the O/W emulsion.
A W/O emulsion was obtained. Next, ammonium sulfate aqueous solution (1.5 mol/ml)
The above O/W/O type emulsion was added to 100 ml with stirring and allowed to react. After the reaction was completed, by the same operation as in Example 1,
4.9 g of spherical silica-walled microcapsules containing camellia oil were obtained. The average particle diameter of the microcapsules is 3.1 μm,
The camellia oil content was 59%. Furthermore, the particle structure of the microcapsules observed with a scanning electron microscope is shown in FIGS. 1 and 2. It can be seen from FIG. 1 that the microcapsules were obtained without agglomerating with each other. Figure 2 shows the surface structure of the obtained microcapsules and the internal structure obtained by destroying the microcapsules, and it can be seen from these that the wall surface of the microcapsules of the present invention has a seamless structure of continuous layers. . Example 5 Linseed oil solution dissolving 2% by weight of polyoxyethylene sorbitan monooleate (HLB=15.0)
2 mol/100 ml of an aqueous solution of cobalt sulfate was added to 25 g and mixed with high speed stirring using a homogenizer to prepare an O/W emulsion. Then sorbitan monostearate (HLB
Add the above O/W type emulsion to 500 ml of n-hexane solution containing 1.5% by weight of a 1:2 (weight ratio) mixture of 4.7) and polyoxyethylene sorbitan monooleate (HLB = 15.0) and shake. Mix and
An O/W/O type emulsion was obtained. Next, 1 mol/aqueous solution of sodium hydrogen carbonate
The above O/W/O type emulsion was added to 1500 ml with stirring and allowed to react. After the reaction was completed, 45 g of reddish-purple cobalt carbonate-walled microcapsules containing linseed oil were obtained by filtration, washing with water, and drying at room temperature for 17 hours or more. The average particle size of the obtained microcapsules is
6.6 μm, and the content of linseed oil was 55% by weight. Example 6 Sorbitan monolaurate (HLB=8.6)
100 g of a saturated aqueous solution of ferric sulfate was added to 30 g of castor oil dissolved in weight percent, and the mixture was stirred and mixed at high speed with a homogenizer to prepare an O/W emulsion. Then sorbitan monostearate (HLB
The above O/W type emulsion was added to 250 ml of a hexane solution (21 g/) of 4.3) and mixed by shaking for 5 minutes to obtain an O/W/O type emulsion. Next, 1 mol/aqueous solution of sodium hydrogen carbonate
The above O/W/O type emulsion was added to 2000 ml with stirring and allowed to react. After the reaction was completed, 45 g of reddish brown hydrated iron-walled oxidized microcapsules containing castor oil were obtained by the same operation as in Example 1. The average particle size of the obtained microcapsules is
7.5 μm, and the castor oil content was 65% by weight. Examples 7 to 22 According to the methods of Examples 1 to 6, microcapsules made of various combinations of wall materials and core materials were obtained using the raw materials shown in Table 1 below.

【table】

【table】

[Brief explanation of drawings]

FIGS. 1 and 2 are electron micrographs showing the particle structure of the microcapsules of the present invention.

Claims (1)

[Scope of Claims] 1. An oil-containing inorganic material containing an oil having a solubility in water of 5% or less or an oily solution using the oil as a solvent in the hollow part of a spherical inorganic hollow body having a porous inorganic wall with a seamless structure. Wall microcapsules. 2 (i) Silicates, carbonates, sulphates, tungstates and halides of alkali metals; sulphates, halides and nitrates of manganese; sulphates, halides and nitrates of iron, cobalt or nickel; and alkaline earths. An O/W type is produced by mixing an aqueous solution containing at least one water-soluble inorganic compound selected from the group consisting of metal halides with an oil having a solubility in water of 5% or less or an oil-based solution using the oil as a solvent. (ii) Next, an organic solvent having a solubility in water of 5% or less is mixed with the above O/W type emulsion to make an O/W/O type emulsion, (iii) Next, an alkaline earth metal halides and nitrates; alkali metal carbonates, nitrates, sulfates, and halides; inorganic acids and ammonium salts thereof; and inorganic bases; Mixing the O/W/O emulsion with an aqueous solution containing at least one compound capable of producing a water-insoluble precipitate by reaction; (iv) filtering, washing with water, and drying the reaction product; A method for producing oil-containing inorganic wall microcapsules.