DE1141263B - Process for the production of an opaque coacerva source - Google Patents

Description

Tannic acid, gallic acid and digallic acid

Offer. "Tannic acid" is a glycoside of gallic acid ~

and / or digallic acid, the exact structure being

tannic acid is not known with certainty. form. The physical properties of the coazer

Coacervate envelopes with solutions from the previous vats usually make further treatment Compounds mentioned below are necessary before the coacervate, which is a light-conditions treated, show an insensitive material encloses, with full effect expected Improving physical properties, ability can be used. such as B. a greatly increased impermeability to Um a useful coacervate coating for light surroundings In order to obtain liquids of both acidic and alkali-sensitive substances, it is necessary that of particular interest in connection the said coating remains intact, except under

those conditions in which exposure of the entrapped material is desired. this means that the coating must be hard enough to withstand the mechanical effects of normal Resist use. The coacervate coating must remain intact under all possible environmental conditions until the correct destructive agent, d. H. a physical, chemical

leaving a phase poor in colloids. The coazer 40 or mechanical agent comes into play, vat has separated itself as a liquid, besides the resistance to premature destruction which in relation to the colloid must have a high concentration, the coacervate must also have a high impermeability tration and in a liquid medium against the passage of molecules or ions, is spergiert, which with respect to the colloid less which adversely affects the entrapped material is. The coacervate initially appears to have 45 flows. If on the other hand a as a fine dispersion of microscopic droplets, the slow release of the substance in the coacervate membrane of the colloid in the low-colloid liquid. If included material is desired, the they are formed in a pure colloidal system, structure of the coacervate of such permeability these droplets are approximately homogeneous. Are, however, that they are the gradual passage of the ambient light-sensitive Substances in the original sol or 50 giving liquids are allowed to release this the original solution tends to cause that. Treatment of a coacervate membrane Coacervate to get around these particles - according to the method according to the invention, results in a

209 748/312

with the great resistance of such coacervate envelopes to acidic and alkaline environments it is through the lightfastness imparted to the coatings treated according to the invention.

The term "coacervate" refers to a colloidal concentrate or one rich in colloids Phase that has separated from an originally single-phase solution or a sol with back-

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new coacervate structure through which the top points of the coacervation colloid in question are located Properties can be achieved. the temperature dispersed to form a double emulsion

The one made possible by the present invention to form in which coacervation occurs. That

Improvement of the coacervate coatings is of the resulting coacervate can then the invention

subject to special interest in connection with a 5 appropriate procedure,

large number of photosensitive materials, with The method according to the invention can also

which one by unusual hardness, great for the treatment of complex coacervates, which one

Controllability of the permeability and opaque emulsions of a hydrophilic liquid in oil to

coating that is marked for non-smoothness are important. So grasp, use, with the coacervate as a compo-

for example, the stability when using io nente at least one gellable hydrophilic colloid,

light-sensitive substances such as reserpine, hyoscyamine, such as gelatin, or a gellable hydrophilic colloid,

Potassium iodide, silver salts, phenyl mercuric acetate and the like, such as gelatin, and at least one linear macro-

can be significantly improved by such coatings. molecular synthetic polymer, e.g. B. a

Also contains vitamins, in particular combinations of styrene-maleic acid copolymers. In the

water-soluble and oil-soluble vitamins, 15 can produce coacervates of this type being a

according to the invention by opaque coacervate primary emulsion of a hydrophilic liquid in oil

cases are protected. You can in this form in an aqueous sol of the aforementioned koazer-

mixed with dry cereal products and dispersed in the four-end colloid to double

Bodies are released. Examples of photosensitive emulsion form. The pn value of this double

Borrowed vitamins are riboflavin, vitamin D and FoI-20 emulsion is then applied to the coacervation area

acid. Insecticides with selective toxicity for insects, discontinued of the coacervation colloid concerned,

which are relatively nontoxic for humans, which leads to the formation of a coacervate from the

are, e.g. B. caused in light impervious coacervate particles of the secondary emulsion

coatings may be included, which will save in, or the coacervation will be caused by thinning

Presence of enzymes of the insects concerned 25 initiated with water,

are very impermeable. The present method can also be used for

The coacervate treatment according to the invention is based on treatment of coacervate envelopes which

on the property of gellable, hydrophilic emulsions of oil in hydrophilic liquid

Colloids, a solution of trivalent iron from close. Such emulsions are made by simple

of the kind described, perhaps produced by 30 or complex coacervation, being a

the replacement of the water of hydration of such hydro-coacervate shell is obtained, which is obtained by the

colloidal together with a previously unexplained method according to the invention improved hardness and

Reaction between the tannic acid, gallic acid or impermeability can be imparted.

Digallic acid, the iron salt, and those named, the coacervates, by the ones described above

Coacervate comprising gellable hydrophilic collo- 35 processes were obtained in which, however, the

iden. The present method is in its on-coacervation by dilution with a solvent

applicability to any particular type of coacervation agent has not been achieved in which the coacervation agent

fathers, d. H. simple or complex, and in no way colloid is less soluble than in water

special way of attaching the coacervates also by the treatment according to the invention

limited. Rather, the present determined min- 40 improved.

At least one gellable, hydrophilic colloid as an improved coacervate can furthermore according to the

Coacervate component the feasibility of the present method can be obtained if the

driving. Coacervate encloses solid particles which, if

Examples of coacervation processes which do not already have a lipophilic character,

Coacervate envelopes result, the physical properties of which are coated with a solid lipophilic coating such as, for. B. bee

properties, such as hardness and impermeability, are provided by wax, before coacervation,

let improve the method according to the invention, In the preferred embodiment of the invention

are in U.S. Patents 2,800,457 and will apply a coacervate coating in a conventional manner to a

2 800 458. Material to be included in these patents is applied. The colloid

write the inclusion of microscopic 50 poor fluid which the coacervate contains

Oil droplets, which dissolved or suspended substances on a below the gelling point of the gellable

may contain, with simple or complex hydrophilic colloid component of the coacervate

Coacervate sheaths. These coacervate envelopes can be cooled at the applied temperature. Which is kept at ph = 4

Finally, treatment with formaldehyde tenen liquid becomes a 10% aqueous solution

are hardened, but as a result no opaque ferric chloride is added with constant stirring

casual coacervate envelopes arise. and stirring continued for an additional 15 minutes. That

Similarly, simple coacervates, gelled and treated coacervates can then be made from

which small droplets of an equilibrium liquid emulsified in oil are filtered off and under

hydrophilic liquid include, after the upstream constant stirring in a 0.01 ° / ₀ aqueous solution

lying procedures are dealt with. The designation 60 of tannic acid introduced which refers to about the same

The term "hydrophilic liquid" includes water that has been precooled at an aqueous temperature. The tannic acid will

Solutions or suspensions and non-aqueous solutions in contact with the for about 30 minutes

Solutions or suspensions which are left with the oil phase of the coacervate, stirring continued

The above emulsions are immiscible. The will, and the coacervate treated in this way is

The emulsion, together with the coacervating 65, is then removed from the solution of the tanning agent that has not been converted.

Colloid used gellable hydrophilic colloid acid filtered off, washed and dried,

in an aqueous solution of a coacervating agent, it is necessary that the coacervate shell before its

such as sodium sulfate, on contact with the iron salt above the gelation to prevent gelation

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that the coacervate is dissolved in it. Random- suitable. Subsequent to the treatment with the

the lower temperature corresponds to the low iron solution, the coacervate is preferably

Geren degree of hydration of said colloids and separately, z. B. by filtration, centrifugation or the like.,

hence a higher density, an important factor around a side reaction between the acid's

to achieve maximum impermeability. Except 5 following stage and the remaining iron salt solution

this gives the coacervate some degree of prevention from gelling.

physical stability necessary for handling. The contact time of the acidic solution with the in the present process is desirable. Pre-coacervate depends on individual requirements. Preferably the temperature of the coacervate is held a certain improvement in the hardness and Undurchwährend throughout the duration of treatment under the <<< permeability compared to untreated gelled-called gel point. Often it is also coacervate, even with a momentary one, the gelled coacervate is desired to be achieved before the treatment solution has another effect, but treatment is carried out from the equilibrium fluid afterwards, which further improves the self-separation, e.g. B. when the volume of this liquid shafts supporting change in the gel structure is relatively large. This can e.g. B. through 15 at reduced speed. A period of filtration or centrifugation can be done. can take about 10 seconds to an hour than usual

The reaction between tannic acid and gallus can be considered for coacervate treatment, where-

acid or digallic acid and the trivalent acids at 30 minutes are suitable for most applications

Iron salts are what causes the opacity of the coacervate membrane.

forth; the appropriate amount of these salts is up to 20. The change in gel structure occurs to a great extent

to some extent by the amount of re- satisfactory manner at pH values below 7. That

acting acid, which subsequently used optimal pn in the acidic range varies depending on the

is determined. On the other hand, this is in turn how each colloid to be treated and the one used

detailed below, limited by the influence of acid. Generally a pH of about 3 to 5 will be used

high concentrations of the above acids to 25 are preferred.

The physical properties of the coacervate It is desirable to keep the reaction mixture during

during treatment. Although the iron salts in the treatment period to constantly stir to good

can be used in a wide range of concentrations, all coacervate particles come into contact with the

d. H. between about 1 and about 30%> will achieve moderate solution and the inclination of each

Concentrations of about 10% usually preferred coacervate particles for agglomeration, particularly

admitted. Quantitatively, the ratio of iron salt to the presence of tannic acid should be reduced. It was

Acid of about 10: 1 to about 10,000: 1 applicable, found that the addition of certain hydrophilic surface

in most cases, a ratio of about surface-active agents, such as polyoxyethylene sorbitol mono-

1000: 1 is preferred. oleat, contrary to the tendency to clump together-

The concentration of tannic acid, gallic acid 35 acts and that it is beneficial as part of the

or digallic acid varies with the desired level of treating solution can be used. amounts

in hardness and impermeability and / or the duration of such hydrophilic surface-active agents

the contact of the compounds mentioned with up to about a hundred times the amount of tanning

Coacervate envelope. It is also dependent on the thick acid, gallic acid or digallic acid are to this

the coating and the intended use of the 40 purposes effective, with about the five to twenty

End product. However, since the aforementioned multiplied amount is preferred.

bonds in high concentrations the tendency For the purposes of the invention, the tannic acid,

have an agglomeration of the coacervate particles gallic acid and digallic acid used alternately

lower concentrations will be without the results of the treatment being significant

preferred. In general, the applied 45 is impaired. Mixtures of the

Concentration range about 0.001 to 1% · In the acids mentioned can be used without the

In most cases, a concentration of 0.01% will leave the scope of the invention or the results

to change an advantageous treatment without difficulty with,

unwanted agglomeration. A convenient and insightful test for that

The required amount of tannic acid, gallic acid 50 consists in the integrity of the coacervate membrane or digallic acid is not critical, but it should be used in the incorporation of a suitable dye into the generally be small compared to the amount of material to be included. The coacervate will open Coacervate to be treated. The area of suitable usual type made and the resulting material Amount ratios of the acids mentioned to that after the treatment according to the invention in the test amount Coacervate comprises about 1:50 to about 1: 1000.55 solution dispersed or immersed. The liquid based on amounts by weight, a ratio can be gently stirred to avoid all of its coacervate about 1: 100 is usually preferred. to expose surfaces extensively. Each through the

The duration of the contact between the iron salt coacervate shell escaping dye trace can be

solution and the coacervate is not critical, it must easily detect in the test liquid

only be so long that the gellable hydrophilic 60 The following examples serve to provide more detailed information

Colloid has the ability to absorb the salt. Explanation of the method according to the invention.

Within about 1 to 30 minutes, most of the _R. .

Coacervate membranes "saturated" with the solution, example

where the exact time of such factors as the A water-in-oil emulsion is at 40 ⁰ C to-

Thickness of the coacervate membrane, the temperature and 65 prepared by adding 10 ml of water in which 10 g

depends on the concentration of the saline solution. Among the potassium iodide are dissolved, emulsified in 25 ml of corn oil,

The usual condition is a touch during which contains 0.25 g of hydrogenated castor oil. A

15 minutes to achieve the desired impregnation Gelatin sol is prepared as a coacervation colloid,

by adding 10 g of gelatin to 100 ml of water. 20 g of sodium sulfate are dissolved in 80 ml of water and this solution is diluted to 100 ml with water. The emulsion and the gelatin sol is heated to 40 ⁰ C and slowly in continuous current in S, the sodium sulfate solution flow allowed, the latter of which was also heated to 4O ⁰ C and stirred vigorously during the period of adding to the influent stream as quickly as possible to disperse, forming a double emulsion of the oil particles in the coacervation mixture. The coacervation occurs rapidly, and after the phase separation is completed, the liquid containing the coacervate-coated emulsion is brought to a temperature of 5 ° C to gel the coacervate. The coacervate mixture is now adjusted to pH = 4. A solution of 10 mg of ferric chloride in 100 ml of water is added to the liquid with constant stirring and the mixture is kept at 5 ° C. for 15 minutes while stirring. The coacervate is then separated by filtration and a solution of 0.1g tannic acid in 1000 ml water containing 0.5 g Polyoxyäthylensorbitmonooleat added at a temperature of 5 ⁰ C and with continuous stirring. Stirring is continued for 30 minutes and the coacervate is then filtered off, washed and dried.

The resulting coacervate is very hard and highly impermeable and gives the trapped Extended protection over a broad acidic and alkaline pH range.

Example 2

Example 1 was repeated, but instead of ferric chloride an equivalent amount of ferric sulfate and gallic acid used in place of tannic acid. A coacervate with similar properties was obtained.

Example 3

In Example 1, ferric chloride is replaced by an equivalent amount of ferric nitrate and tannic acid Digallic acid, a coacervate with similar properties is obtained,

Example 4

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If you proceed according to Example 1, but without the pn the liquid containing the coacervate-coated emulsion, as set there, is obtained a hardened coacervate with a slightly lower hardness and impermeability.

Example 5

An ethanol-in-oil emulsion is produced at 50 ° C, by adding 33 ml of ethanol, in which 10 g of silver bromide and 0.2 g of tragacanth are dissolved, in 33 ml

Silicone oil, which contains 4 g of beeswax, emulsifies. A gelatin sol is prepared from 12.5 g of gelatin and 125 ml of water ^{at 50 ° C. and the sol obtained is mixed well with the emulsion.} This mixture is slowly added to 125 ml of a 20% barium chloride solution, the barium chloride solution being stirred vigorously for the duration of the addition in order to facilitate coacervate formation. The temperature of the solution containing the coacervate-coated emulsion is lowered to 5 ° C. and 500 ml of a 10 ° / ₀ strength aqueous ferric bromide solution, also at 5 ° C., is added slowly and with stirring. After 5 minutes, the coacervate is separated off by filtration and added, with stirring, to 200 ml of a 0.05% aqueous solution of tannic acid. Stirring is continued for an additional 30 minutes while maintaining the temperature at 5 ° C. The coacervate treated in this way is separated off by filtration, washed and subjected to spray-drying. The product is then processed in the usual manner into a dry preparation which can be used as an insecticide.

Claims (4)

PATENT CLAIMS: 1. A process for producing an opaque coacervate shell which contains at least one gellable hydrophilic colloid with amino groups and peptide bonds, characterized in that the coacervate is treated with an ionizable trivalent iron salt and then with tannic acid, gallic acid or digallic acid. 2. The method according to claim 1, characterized in that before the treatment of the Coacervate with an ionizable trivalent iron salt increases the pn value of the coacervate Medium to below 7. 3. The method according to claim 2, characterized in that after setting the pn value to below 7 and before treating the coacervate with an ionizable trivalent Iron salt cools the coacervate below the gelling point of the gellable hydrophilic colloid. 4. The method according to claim 3, characterized in that the coacervate with an aqueous Treated solution of an ionizable trivalent iron salt, the treated coacervate vom liquid medium separates, the separated coacervate with an aqueous solution of tannic acid, Treated gallic acid or digallic acid and the treated coacervate from the reaction mixture separates. Considered publications:
U.S. Patent No. 2,800,457. 1 209 748/312 12.62