DE1186828B - Process for making very small capsules by coacervation - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. CL:

Number:
File number:
Registration date:
Display day:

Gusty

German KL: 12c-3

1186 828
N20754IVc / 12c
October 31, 1961
February 11, 1965

It is known to form individual capsules by gelatinizing one by coacervation with stirring to produce water-insoluble cores of deposited, polymeric, liquid capsule wall-forming substance. During coacervation, the nucleus-forming and the liquid, capsule-wall-forming substance are present as a mobile dispersion in an aqueous liquid, the temperature of which is above the gelatinous point lies, so that the gelatinizable, capsule wall-forming substance is initially in the liquid state.

Coacervation is achieved by adding a salt or changing the pH of the dispersion causing substance reached.

By cooling to a temperature below the gelatinization temperature of the polymeric substance the liquid coacervate shell is solidified in a shell protecting the core, making it self-supporting Capsules are created. The nucleating substance is dispersed in the aqueous sol before or after coacervation.

You can now produce very small, water-insoluble solid or liquid substances containing Capsules by coacervation of one or more hydrophilic film-forming macropolymers, at least one of which is gel-forming in an aqueous liquid by means of coacervation causing substance, wherein the substance to be encapsulated is added, and by solidifying the formed Coacervates by cooling initially at low temperature a system from in an aqueous one Produce liquid dispersed polymer and coacervation causing substance in which There is still no liquid deposition of the polymer and, if the core-forming substance is already in the watery one Liquid is dispersed, no coating takes place, in which this deposit or coating but after heating to a temperature at which the polymeric phase becomes liquid, takes place. In addition According to the invention, the polymer (s) mentioned is (are) in water with which the coacervation causing substance mixed below the gel formation temperature of the gel-forming polymer and the Mixture heated and stirred to a temperature above the gelation temperature and in known Then, while stirring, bring it to a temperature below the gelation temperature cooled down.

At the low temperature at which the dispersion of the polymer and the phase separation initiating substance, with or without a nucleating substance, is made, the polymeric substance does not dissolve. Processes for making very small capsules
by coacervation

Applicant:

The National Cash Register Company,

Dayton, Ohio (V. St. A.)

Representative:

Dr. A. Stappert, lawyer,

Düsseldorf, Feldstr. 80

Claimed priority:
V. St. v. America November 4, 1960
(67 158)

but remains largely as a disperse solid phase. The dispersion of the polymeric substance remains stable for a long time.

The starting mixture can therefore be prepared and stored in an open or closed container, e.g. B. Cans or jugs. The actual capsule production can then optionally to be done later. Since in the simplest case only a heating, stirring and If cooling of the starting mixture is required, these steps can also be carried out by non-experts Hand simple instructions to be carried out.

Even if the nucleating substance, which can be easily introduced, is not yet in the This makes the production of capsules in large quantities very much easier simplified. The starting mixture is transportable.

The capsules can also be made using a single vessel and in a single aqueous solution Dispersion liquid can be prepared. During the first step in which the dispersion is formed and the correct proportions are created, no heating is required.

The macropolymers, the substance causing the coacervation and, if applicable, the one to be encapsulated Substance can also initially be in a dry, finely powdered state or in the form of an agglomerate, which is easy to break apart and disperse in water, mixed and only then in water

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be dispersed. The aqueous dispersion of the The starting mixture can also be dried, after which a mixture of the dispersed solids in finely powdered form remains. The change in pH caused by the removal of the aqueous vehicle the remaining system can be removed by adding a pH-regulating substance balance.

You can also first introduce the macropolymers in water, dissolve in the heat and bring them to 25 ° C cool and add the substance causing the coacervation while stirring, whereby the storable Starting mass as a flaky solid precipitate with a particle size in the order of magnitude forms between 1 and 100 μ.

Gelatin obtained from warm-blooded animals is particularly suitable as a macropolymer. To the simple and complex coacervation can include gum arabic, polyethylene maleic anhydride, Polyvinyl methyl ether-maleic acid so anhydride, polymethacrylic acid or combinations of which are used in complexes with gelatin.

As a substance to be encapsulated z. B. Cassia oil, of which, although it is slightly mixed with water »5 is miscible, the whole undissolved part can be encapsulated, or vegetable, animal, synthetic and mineral oils such as corn oil, cottonseed oil, linseed oil, castor oil, peppermint oil, perfume oil essences of plants, bacon oil, sperm oil, methyl salicylate, petroleum fractions, trichlorodiphenyl, or magnetic iron oxide alone or suspended in oil, Pigments, pigmented oils (e.g. inks), crystalline or amorphous powders (e.g. dyes and Drugs) or hexane, pyromellitic anhydride, carvone, riboflavin, zinc sulfide and barium sulfate be used.

example 1

40

It becomes a starting mixture of 20 g of pig skin gelatin with an isoelectric point at pH = 8.9, 980 g of water, 800 ecm of a 20 percent by weight aqueous solution of ammonium sulfate and 200 ecm of corn oil. This starting mixture can be stored. If you use it later, stir it on a Heated temperature between 35 and 50 ° C. The mixture is then stirred until Capsules with liquid walls have formed, which are then cooled to room temperature (20 to 25 ° C) self-supporting and, if desired, hardened.

Example 2

There is a starting mixture of 10 g of gelatin extracted from an acid, 10 g of gum arabic and, depending on the desired particle size, 20 to g of iron oxide powder are produced. The gelatin will obtained from pigskins. The degree of acidity of the gelatin is such that after the introduction of the dry Mix in 800 g of water and warm to 35 to 55 ° C, the pH of the system between 3 and 4 lies. The gelatin and gum arabic then form a complex liquid phase and deposit on the iron oxide particles. The liquid wall around these particles is created by subsequent cooling brought to gelatinize below the gelatinization temperature. This creates capsules that are made from Water can be separated and dried.

The capsules can be hardened in a known manner, for example with formaldehyde or glutaraldehyde will.

Claims (2)

Patent claims: 1. Process for the production of very small, water-insoluble solid or liquid substances containing Capsules by coacervation of one or more hydrophilic film-forming macropolymers, at least one of which is gel-forming, in an aqueous liquid, by means of a die Coacervation causing substance, wherein the substance to be encapsulated is added, and through Solidification of the coacervate formed by cooling, characterized in that that the (s) polymer (s) in water with the substance causing the coacervation below the Gel formation temperature of the gel-forming polymer are mixed and the mixture on heated and stirred to a temperature above the gelation temperature and in a known manner then cooled with stirring to a temperature below the gel formation temperature will. 2. The method according spoke 1, characterized in that the substance to be encapsulated Mixture is added before or after increasing its temperature. Considered publications:
German interpretative document No. 1 017 905.