DE1185154B - Process for the production of very small particles which contain a liquid emulsified in oil inside by coacervation - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Boarding school Class: B Ol g

Number:
File number:
Registration date:
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German KL: 12c-3

1185154
U6734IVc / 12c
December 12, 1959
January 14, 1965

U.S. Patents 2,800,457 and 2,800,458 teach methods of encapsulating oil droplets described by coacervate coatings of a complex or simple type. Accordingly, coacervates are made from an oil-in-water emulsion, but only the oil phase is encapsulated by the coacervate. As a coacervation solution, for. B. used an aqueous gelatin sol.

It has now been found that very small particles, which are inside a hydrophilic liquid emulsified in oil contain, through complex coacervation with the help of at least two coacervating polymers, one of which is a hydrophilic colloid can be made using the present invention adding a stabilizer to the emulsion in the oil phase and in the presence of an aqueous dispersion, In addition to the hydrophilic colloid, a styrene-maleic acid or styrene-maleic acid amide copolymer or contains a carbohydrate acetate phthalate, coacervated in a known manner.

By adding a thickener, e.g. B. methyl cellulose, to the hydrophilic liquid phase the emulsion can be achieved by fixing the dissolved or suspended substance during coacervation the effectiveness of the coacervation process and the properties of the encapsulated obtained Product to be improved.

The term hydrophilic liquid here includes water, aqueous solutions or suspensions and non-aqueous solutions or suspensions that are immiscible with the oil phase of the primary emulsion are.

Emulsions can also be encapsulated that contain dissolved or suspended substances in the oil phase contain. The invention can also be applied to the encapsulation of particles already in a coacervate membrane are included.

It is thus possible to produce particles with impenetrable coatings of high strength or coatings which allow a gradual release of the water-soluble content. The encapsulated particles may contain substances which are used in agriculture as slow-acting fertilizers, hormones affecting the growth of plants, and pesticides such as fungicides, nematocides, bactericides, viricides, etc. The ingredients can also be incorporated into premixed feeds, which is normally not possible because of losses in the drying process, as the encapsulated ingredients are released from the stress exerted on them in a pre-actual use process for making very small ones
Particles that have an emulsified in oil inside
Containing liquid due to coacervation

Applicant:

The National Cash Register Company, Dayton, Ohio (V. St. A.)

Representative:

Dr. jur. W. Beil, A. Hoeppener
and Dr. HJ Wolff, lawyers,
Frankfurt / M.-Höchst, Antoniterstr. 36

Named as inventor:

Everett Nelson Hiestand,

Erik Hugo Jensen,

Peter Dietrich Meister, Kalamazoo, Mich.

(V. St. A.)

Claimed priority:
V. St. y. America December 22, 1958
(781922)

Are exposed to the mixer stage. Similarly, vitamins, especially combinations of in water and in oil-soluble vitamins, incorporated into dry grain products, from which they enter the body reach. Cosmetics can be produced, with the agent in question in impenetrable, however, easily destructible coacervate coatings can be enveloped. Pharmaceutical agents can be encapsulated so that they come into contact with an area that was previously identified pH value, or can act slowly on the body with an enzyme system, or in cases where there are difficulties with persistence, smell, taste or the intolerance exist. Such products can be coated and then used orally, applied topically or injected, depending on how the particle size and coating thickness, Permeability and hardness, or how the coacervation ingredients are selected. Insecticides that have selective toxicity for insects, but are relatively harmless to humans, can e.g. B. be encapsulated in coacervate coatings, except in the presence of insect enzymes

409 768/254

Claims (3)

are highly impermeable. Rat and mouse poisons which are effective when swallowed by animals, but which have a warning or repellent odor, can also be coated according to the method of the invention, whereby they become completely impermeable to the odor. The hydrophilic colloids in question include specifically the naturally occurring ones. Example 1 100 g of chloral hydrate are dissolved in 50 cm3 of water and heated to 70.degree. 25 g of beeswax are dissolved in 125 cm3 of mineral oil at 70 ° C. The aqueous solution is emulsified in the oil solution by passing the combined mixture through a homogenizer four times. 75 g of styrene-maleic acid mixed polymer are dispersed in 1500 cm3 of water gellable and non-gellable hydrophilic collo- io, heated to 70 ° C and as much 10 ° / »iges ide and its derivatives, such as gelatin, agar-agar, sodium hydroxide are added, that the mixed poly-albumin, deacetylated chitin, pectins, gummimers dissolve. At this point the interpolymer has arabic, starch, fibrinogen. The poly solution used has a pH value between 7 and 8. Under fortmere contain both lipophilic and hydrophilic. B. of styrene, a 15 mixed polymer sol dispersed. 75 g of gelatin are ring alkyl-substituted styrene or ether dissolved in 500 cm3 of water at 70 ° C, and it is so groups, ester groups or halogens substituted a lot of 10% sodium hydroxide added that the styrene or z. B. of maleic acid or the pH of the sol rises to 7. Taking constant maleic acid amide off. This lipophilic and hydro- stirring the gelatin sol is added dropwise to the philic units, preferably together with the 20 interpolymer-emulsion mixture. Directly the largest part of what is then present in the interpolymer is then present at 70 ° C and under perpetual polymer units. Other polymers can also be contained in the interpolymer dropwise 20% acetic acid solution after stirring, for example, to increase the pH of the mixture 4.5 styrene-maleic anhydride mixed poly- sinks to be hydrolyzed. The mixture is mixed for 30 minutes at 70.degree. C. and carbohydrate acetate phthalate, such as starch, then it is converted to acetate phthalate, cellulose acetate phthalate and amylose acetate phthalate within 30 minutes. The hydrolyzed styrene 37% formaldehyde solution of polymers is added and maleic anhydride copolymers preferably 1 hour later a sufficient amount of 10% is used, the anhydride groups of which are preferably 30% sodium hydroxide, in order to bring the pH to 8, at least 50%. heights. The coacervate is then filtered with water. The copolymers used are known. Since their solubility is different, known solubilizers can be used. The choice of oil depends on the functions, 35 1.5 g of a green, water-soluble dye it is intended to perform, i.e. i.e. whether it is a solvent to be dissolved in 150 cm3 of water at 50 ° C. 1 g or suspension medium is used or only as the external phase of the primary emulsion. Practically all animal, vegetable, mineral or synthetic oils can be used for this purpose, which have the desired physical properties 4 ° four times through a hand homogenizer. directs. 50 g of cellulose acetate phthalate are dissolved in 700 g. Examples of such oils are lanolin, corn oil, soybean oil, water at 50 ° C. and sufficient castor oil, cod liver oil or mineral oil. If 10% sodium hydroxide is added to the preparation of the emulsions, the pH of the solution will usually be raised to between 7 and 8, which are common emulsifiers such as polyvalent esters. 50 g of fibrinogen are dissolved in 700 cm3 of cold alcohol, sorbitan derivatives and sorbitan polyoxy water and heated to 50 ° C. It is cooled down as much as 5 ° C. Then it is kept at a temperature of less than 10 ° C for 1 hour. 75 cm3 and dried by freezing at 40 ° C. Example 2 Hydrogenated castor oil is dissolved in 100 cm 3 of corn oil at 50 ° C. The aqueous solution is emulsified in the oil by using the combined liquids, ethylene derivatives. Suitable stabilizers are all substances which prevent the reversal of the hydrophilic liquid-in-oil emulsion into an emulsion of an oil in a hydrophilic liquid during the dispersion of the emulsion in the coacervation medium. These include surface-active agents, preferably of the nonionic type, and oil thickeners, such as natural and synthetic waxes, solid fats, added hydrochloric acid, sterols and other common agents that gel or thicken oil. Examples of surface-active agents are sorbitan fatty acid esters and polyoxyethylene sorbitan fatty acid esters. 10% sodium hydroxide was added to the oil thickeners so that the pH of the fibrinogen dispersion rose to between 7 and 8. The cellulose acetate phthalate solution and the fibrinogen solution are combined. The emulsion is emulsified in these combined solutions with continued stirring. Immediately after the emulsion has been added, so much 10% is added dropwise that the pH of the mixture falls to 3.0. The mixture is now stirred at 50 ° C. for 30 minutes. It is then cooled to 5 ° C. within 30 minutes. 50 cm3 37% formaldehyde solution are added and 2 hours are e.g. B. beeswax, carnauba wax, paraffin - 60 later so much 10% sodium hydroxide that the wax, saturated fatty acid esters, sitosterol, chole pH rises to 8.5. Then the coacervate becomes sterol, stigmasterine and hydrogenated castor oil. The known natural and synthetic thickeners such as gum arabic, tragacanth, methyl cellulose, carboxymethyl cellulose can be used as thickening agents for the hydrophilic liquid. Magnesium aluminum silicate, polyglycols, glycerin and syrups can be used. centrifuged, washed and air-dried at 90 ° C. Patent claims: 1. Method of making very small particles having inside an emulsified in oil contain hydrophilic liquid, by complex coacervation with the help of at least two coacervating polymers, one of which is a hydrophilic colloid, characterized in that that a stabilizer is added to the emulsion in the oil phase and in the presence an aqueous dispersion which, in addition to the hydrophilic colloid, is a styrene-maleic acid or Contains styrene-maleic acid copolymer or a carbohydrate acetate phthalate, in known Way coacervated. 2. The method according to claim 1, characterized ge ίο indicates that the stabilizer used is nonionic, surface-active agents or oil-gelling agents Agents such as hydrogenated castor oil or sorbitol monooleate are used. 3. The method according to claim 1 and 2, characterized in that an emulsion is used, which is a thickener in the hydrophilic liquid phase, ζ. B. methyl cellulose contains. Considered publications:
U.S. Patent No. 2,800,458. 409 768/254 1.65 © Bundesdruckerei Berlin