DE2602176A1 - Microencapsulated hardeners and vulcanising agents - contg. basic metal cpds. treated with hydrophobising agent - Google Patents

Abstract

Micro-capsules contg. basic cpds. (A) of di- and tetravalent metals of Groups II and IV, and sub-group VII, are treated with a hydrophobising agent, (B). The metal cpd. is pref. PbO2, MnO2 or ZnO, and (B) is a halogenated paraffin, perfluoropolypropylene oxide, silicone oil or silane. Used as hardeners and vulcanising agents for polymers, esp. adhesives and sealants based on polysulphide, polychloroprene, SBR and NBR rubbers. Stable one-component systems with high rates of hardening can be made. Addn. of (B) prevents diffusion of the metal cpd. into the acid coacervation mixt. during encapsulation and consequent changes in pH. Reaction between the metal cpd. and the capsule wall, making the capsules difficult to break when required, is prevented.

Description

Microcapsules containing metal compounds,

especially as a hardener for polymerizations and as a vulcanization aid and Methods for Making Such Microcapsules "The invention relates to microcapsules with a content of oxidic metal compounds of metals of the II. and IV. and subgroup and the VII. subgroup of the periodic table, especially for the Use as a polymerization hardener or vulcanization aid and a process for the production of such microcapsules.

It is known that with the help of microencapsulation technology, the smallest Liquid and solid masses in the form of so-called microcapsules with a solid, closed Shell can be surrounded. This allows chemically reactive substances up to their Use to be disabled. The microencapsulation is therefore a valuable one Aids in the broadest areas of technology, e.g.

also for polymer chemistry and environmental protection.

For example, those usually designed as 2-component systems are subject to this Polymer systems with high curing speeds and therefore very short pot lives are common considerable qualitative fluctuations, as the mixing ratios are adhered to and homogeneous mixing is often not given sufficient consideration. Are the other way around conventional 1-component systems because of their general

very long curing times uneconomical because they are not further processed for a long time or material pairings connected with their help cannot be loaded for a long time.

Through the use of microencapsulated catalysts, hardeners and / or Accelerators can remedy these disadvantages. The intimate mixtures of polymerizable Material and metal compound-containing microcapsules is immediately before use in situ by destroying the microcapsules and thus releasing the catalysts, etc. reactivated. In this way, 2-component systems become storage-stable 1-component systems in which, with the help of microencapsulation, very high curing speeds can be achieved.

While the microencapsulation of certain radical-forming catalysts and accelerators, such as organic peroxides and tertiary amines, as dissolved in principle can be considered a satisfactory microencapsulation is more oxidic Metal compounds, in particular of metals of the II. And IV. Main and sub-group as well as the group of the periodic table, such as those used as hardeners and vulcanizing agents for polymers, especially for adhesives and sealing compounds on polysulphide, polychloroprene, Styrene-butadiene and butadiene-acrylonitrile-based etc. are not used so far possible.

When microencapsulating such metanoxidic verbs? fertilize Problems arise, which are mainly based on the basicity of the metal compounds. In addition, with microencapsulated solids, because of the interaction between Solid and capsule wall material, the mechanical stability of the microcapsules so great that in many cases the capsule opening is available in practice standing only moderate forces no quantitative Destruction of the Microcapsules and therefore no complete release or reactivation of the metal compound is possible. This disadvantage can be avoided in that the finely divided Solids converted into stable suspensions or pastes with the aid of liquids will.

Understandably, diffusion-tight capsule walls are sought. This is for example for the use of microencapsulated metal compounds as Hardeners or vulcanization auxiliaries are a mandatory requirement. Diffusion density According to the current state of knowledge, capsule walls can only be made through complex ones Coacervation can be established. Practically all can be used as capsule wall materials Natural and synthetic polymers are used that have film-forming properties and react with each other in the complex coacervation, such as gelatin, Gum arabic, carrageenan, methyl cellulose, polyvinyl methyl ether-maleic acid copolymers, Polyvinyl chloride, polyphosphates, polyvanadates, polymolybdates, etc. In microencapsulation In contrast, oxidic metal compounds arise with the help of simple coacervation only semipermeable capsule walls, which consequently do not contain the oxidic Metal compounds and thus, for example, when using such Microcapsules as a hardener in polymerizable compositions, the mixture has no storage stability, in particular at higher temperatures.

The aforementioned basicity of the metal compounds is based on the following Reason poses a particular problem. The microencapsulation of the oxidic metal compounds takes place by means of complex coacervation with water as the carrier phase; the encapsulation takes place in an acidic medium. When emulsifying the oxidic metal compound or Metal oxide pigments therefore undergo hydrolysis, which, due to diffusion or the non-negligible solubility of the resulting metal oxide hydrates or Metal hydroxides in the acidic carrier liquid, not limited to the surface remain. The pH does not remain constant as required, but occurs pH shift to higher pH values, in some cases into the strongly alkaline range into, a. If encapsulation is still possible at all, it will not work to diffusion-tight microcapsules.

Encapsulation is possible to a certain extent by that the pH value required for coacervation is achieved through continuous addition of acid is kept constant, but this occurs because of the high degree of ionization the colloid-rich phase a decoacervation that causes the formation of agglomerates has the consequence. Such agglomerates are not actually microcapsules, but only metal oxide particles stuck together with coacervate, which have no mechanical stability whatsoever during subsequent processing, none have complete enclosure and thus do not guarantee inactivation.

In addition, keeping the pH constant by adding acid leads to such a situation high ion concentration that there is a permanent conversion of the oxidic metal compounds in the direction of salt formation, leading to permanent inactivation the surface of the metal oxide. Even if you preform the coacervate, A spontaneous encapsulation of the metal compounds when added to the encapsulation medium To achieve this, no closed coacervate shell can be formed.

The invention now relates to microcapsules containing oxidic metal compounds of divalent resp.

bivalent and tetravalent metals of the II. and IV. main and sub-group and the VII. subgroup of the periodic table, especially for use as Polymerization hardeners or vulcanization auxiliaries, wherein according to the invention the Metal compounds contained in the microcapsules carry a water repellent. In fact, it has been shown that the microcapsules according to the invention provide the task could be solved successfully.

For the purposes of the invention, oxidic metal compounds are those Compounds of the II. And IV. Main and sub-group and the VII. Sub-group of the Periodic table to be understood as oxides, oxide hydrates, or even hydroxides present as basic salts. The metals of the II.

The main and subgroups are electropositive and bivalent Form that of the IV. Main and subgroup and the VII. Subgroup in electropositive bivalent or tetravalent form. The corresponding ones are particularly preferred Compounds of lead, manganese, zinc, especially lead IV oxide, manganese IV oxide and Zinc-II-oxide. In general, the bivalent and tetravalent oxides of the metals of the II. and IV.

Group of the periodic table preferred.

The usual substances known for this purpose can be used as water repellants are used, especially those substances whose electronegativity is greater than it has the oxygen contained in the respective metal oxide. In particular have the known chlorine- and fluorine-containing organic water repellants proven. Examples are haloparaffins, e.g.

B. chlorinated paraffins, perfluoropolyalkylene oxides, e.g. perfluoropolypropylene oxides, Silicone oils, silanes, mercapto-functional silanes, e.g. mercaptopropyltrimethoxysilane.

Such water repellants are understandably within the meaning of the invention preferred that are stable to water and also in the acidic pH range and if possible have a high affinity for the metal compound. As large a number of Atoms with the highest possible electronegativity in the molecule or strongly ionic bond components can be beneficial. Provided atom groups with strongly ionic bond components present, the redox potential must be with respect to the metal atom in the metal compound be so small that no redox reactions take place between the metal oxide and the water repellent.

In a preferred embodiment, the microcapsules contain Use as a polymer hardener or vulcanization aid, in coordination with the respective polymer or

Vulcanizate, and the desired properties, plasticizers, e.g.

B. Ester plasticizers, such as phthalates and adipates, phosphoric acid esters, Fatty acid derivatives, ketones, etc. The microcapsules can, however, also, if appropriate In addition to plasticizers, they contain carriers in liquid or solid form, in particular Substances inert to the oxidic metal compounds.

For microcapsules with oxidic metal compounds and plasticizers or other additives, such as carriers and the like, there is sometimes the Danger that because of the high specific in comparison to the organic compounds Weight of the oxidic metal compounds sedimentation of the particles of the heavier ones Metal compound enters the microcapsule. This can be so be pronounced that when the microcapsules are destroyed, the plasticizer or other additive escapes, but the metal compound largely on the inner wall of the capsule remains adhering, so that a complete release and homogeneous mixing and quantitative Reaction with the co-reactant is not possible. In a further preferred embodiment The present invention therefore also relates to microcapsules of the aforementioned type, where to reduce or avoid sedimentation or segregation the internal phase contains a water repellent that has a higher specific Weight and / or a higher viscosity than the plasticizer or other Additive, namely carrier.

The microcapsules can also be known for the particular purpose contain appropriate ingredients, e.g. pigment stabilizers, dispersants, etc.

The invention further relates to a method for producing the products according to the invention Microcapsules with a content of oxidic metal compounds of the metals of the II. and IV. main and subgroup and the VII. subgroup of the periodic table, where according to the invention the metal compound prior to microencapsulation with a water repellent is treated. For the water repellants to be used here, of course, apply the previous ones relevant statements in full. It are in turn haloparaffins, perfluoropolyalkylene oxides, silicone oils, silanes and like used. Chlorinated paraffin is preferred, especially with a specific one Weight greater than 1.2 g / ml and a viscosity greater than 1000 cP is used.

In order to achieve a uniform and sufficient hydrophobization, it is recommended to use the metal compound or the metal compound-plasticizer mixture homogenize with the hydrophobizing agent using intensive mixers.

Repeated rubbing has proven to be the most common of the investigated procedures best proven with the three-roller mill. Provided that they are approximately the same Wetting of the particles of the metal compound with the hydrophobizing agent the hydrophobizing effect and thus the pH stability in the carrier liquid for a given class of waterproofing agent, a function of the viscosity of the waterproofing agent. The hydrophobizing and thus pH-stabilizing effect generally decreases with increasing viscosity of the hydrophobizing agent.

The optimal capsule spectrum and phase ratio is determined by the consistency and the degree of filling of the internal phase and from the Requirements for mechanical stability when incorporating into other materials and those available during reactivation to destroy the microcapsules Forces determined. In microencapsulation, the phase relationship is understood the mass ratio of the internal phase, i.e. the substance to be encapsulated to the external wall material phase. As the phase ratio becomes smaller, it increases for a given Capsule spectrum increases the mechanical stability of the microcapsules, i.e. the risk of involuntary destruction of the microcapsules during the production of mixtures takes place from, while vice versa to the destruction of the microcapsules when using such Masses higher forces are required. For the use of such microcapsules there is therefore an optimal compromise from formulation to formulation.

The microcapsules according to the invention have a capsule spectrum of preferably about 100-2000m, in particular 400-1200 o m. The phase relationship of the internal The phase to the wall material phase is 4: 1 to 20: 1, but preferably 12: 1 to 14: 1.

Such microcapsules according to the invention have a sufficient one mechanical stability around in dry, free-flowing form by means of conventional Methods such as

B. with planetary mixers without noticeable capsule destruction in others Masses, e.g. to be able to be incorporated into polymer or filled polymer masses. In the production of highly filled compounds, such as sealing compounds, however, this can high shear forces occur that may

a catalytically active capsule rupture occurs. In this case it has it has proven to be useful to first insert the microcapsules into the unfilled polymer incorporate and then add the fillers or the capsule surface to be pretreated with system-compatible wetting agents to increase the sliding properties.

The flow behavior of the mixture of metal compound and hydrophobizing agent or the other additives, such as plasticizers, etc. are adjusted so that during emulsification the desired capsule spectrum is achieved. As a viscosity regulator, e.g. low molecular weight, low viscosity types of the hydrophobizing agent used in each case, which do not affect the pH stability and because of their approximately the same specific Weight have no influence on the sedimentation behavior of the internal phase, be used. In the case of low-viscosity water repellants, this may be negative The viscosity setting can be expected or exert an influence on the end product also about other substances, e.g. also about Plasticizers such as dibutyl phthalate, if they are compatible with the water repellent used are, as after previous hydrophobization despite the addition of softener a sufficient hydrolysis stability is maintained for microencapsulation.

The concentration of the metal compound in the substrate is generally as high as possible for economic and technical reasons. By incorporating high concentrations of metal compounds in the water repellent however, its flow behavior change, so that the encapsulation Particle size of the dispersed phase can only be adjusted poorly; a very broad one This can result in a capsule spectrum of approx. 20 to 2000 ohm.

The emulsification behavior can be improved and a narrower capsule spectrum can be achieved if, before encapsulation, surface-active substances, in particular fluorinated carboxylic acids or sulfonic acids are incorporated.

The following diagram clearly shows the advantages achieved according to the invention, in particular the pH value: pH value change at 40 ° C. in 5% aqueous gelatin solution: A: PbO2 pigment; B: PbO2 pigment / chlorinated paraffin (1: 1) The following examples serve to illustrate the invention.

Example 1: 200 g of lead IV oxide are mixed with 200 g of chlorinated paraffin, the a specific weight of 1.42-1.54 g / ml at 200C and a viscosity of approx. 40,000 cP at 200C, with the help of an agitator with a so-called friction disc equipped, pasted. This creates a mixed mix with local ones PbO2 concentration differences. This mixture is then on a three-roll mill rubbed off three times, working with a very small gap width and the The scraper is adjusted so that a practically quantitative return to the goods he follows.

After rubbing it three times, a paste is produced, its microscopic Investigation of a completely homogeneous distribution of the pigment in the carrier phase shows. Storage tests with this paste showed that the homogeneity and resistance to hydrolysis not just in a period of time sufficient for encapsulation, but over several Months. 200 g of the PbO2 plasticizer paste thus obtained were then added encapsulated.

To this end, 180 g of an 11% gelatin solution are added 180 g of an 11% aqueous solution of gum arabic with 500 g of demineralized Water mixed. As a gelatin, pig skin gelatin is used with an isoelectric Point used at pH 8 to 9 and a bloom strength of about 285 to 305 g. That The aqueous system obtained in this way is heated to about 50 ° C. with stirring, during which adjusts a pH value of 4.5. 200 g of the Pb02 plasticizer paste are added to this solution while stirring and emulsifies to a droplet size of approx. 300 to 10006m. While stirring is the emulsion is slowly cooled to 280 ° C., during which time coacervation occurs. Afterward is rapidly cooled to a temperature of 5 to 100 ° C. while stirring, 16 ml of glutaraldehyde added and the mixture was stirred for a further 16 hours, the temperature rising to approx. 20 ° C. The resulting microcapsules are then washed several times with water, over a Filter off the Büchner funnel and cut the capsule cake into pieces on a sieve dried in a stream of air.

Example 2: The Pb02-chlorinated paraffin paste is produced according to Example 1 and encapsulated. After hardening with glutaraldehyde, the microcapsules become In extension of Example 1, however, washed 3 times, the aqueous solution so far decanted as possible and replaced by the same volume of a saturated, watery Replaced sodium sulfate solution. This is used to shrink the microcapsules. To 16 hours of stirring at 20 to 250C is then used to isolate the microcapsules, such as Describe under Example 1, continued.

Example 3: 400 g of a commercially available Pb02 plasticizer paste become to improve hydrolysis resistance 200 g of specific chlorinated paraffin Weight 1.42 - 1.54 g / ml at 200C and a viscosity of approx. 40,000 cP at 200C added, premixed with a friction disc and to achieve sufficient Homogeneity and pH stability rubbed 4 times on a three-roll mill. The so The paste obtained has sufficient hydrolysis stability for encapsulation for about 2 weeks. The encapsulation takes place according to the following process: 500 g of a 10% gelatin solution (160 bloom grams) are mixed with 250 g of demineralized water and heated to 450C warmed up. 150 g of a 5% polyphosphate solution are added to this solution, a pH of 4.8 is established. With continuous stirring are now 600 g of PbO2-plasticizer-chlorinated paraffin paste are added and the paste to a diameter emulsified from approx. 400 to 1600rom. Now the pH is raised by means of sulfuric acid approximately 4.2 and the temperature of the emulsion slowly and continuously to 30 0C lowered. It is then quickly cooled to a temperature of 5 to 100C, 25 g of glutaraldehyde were added and hardened for 16 hours. To isolate the microcapsules the procedure is then carried out as described in Example 1.

Example 4: 200 g of Pb02 pigment, 100 g of specific chlorinated paraffin Weight 1.42 - 1.54 g / ml at 200C and a viscosity of approx. 40,000 cP at 200C and 0.1 g of Turkish red oil are premixed with a friction disk and twice on the Three-roller mill abraded. To adjust the encapsulation viscosity are then 300 g of chlorinated paraffin with a specific gravity of 1.17 - 1.19 g / ml at 200C and one Viscosity of approx. 2000 to 2500 cP added and the mixture at very low Gap width rubbed off again 3 times on the three-roller mill. The one made in this way Paste shows with regard to the pH stability in the case of the encapsulation carried out according to Example 1 no change even after 3 months. The microcapsules produced according to the invention do not show any sedimentation in the internal phase after 1 year.

Example 5: 200 g of Pb02 pigment and 150 g of specific chlorinated paraffin Weight 1.42 - 1.54 at 200C and a viscosity of approx.

40,000 cP at 200C are mixed with the help of a friction disk and 0.1 g of a fluorinated wetting agent (FC-170 from 3-M Company) was incorporated. These Mixture is rubbed 3 times on the three-roll mill and then for viscosity adjustment incorporated 200 ml of octyl phthalate using the friction disc. The one made in this way The PbO2 chlorinated paraffin plasticizer system has one for technical microencapsulation sufficient pH stability for a period of approx.

4 weeks. In the case of the encapsulation according to Example 2, the same takes place Stirring speed a more uniform emulsification and thus a capsule spectrum from approx. 400-1000 Xm.

Example 6: 200 g of manganese IV oxide pigment are mixed with 200 g of chlorinated paraffin with a specific gravity of 1.42 - 1.54 g / ml at 200C and a viscosity of approx. 40,000 cP mixed with the help of a friction disc and 0.075g of a fluorinated surfactant Substance (FC-170 from 3-M Company) incorporated. This mixture is then 4 times intensively rubbed on the three-roller mill and encapsulated according to the following process: In 200 g of an 11% solution of a 300 bloom gelatin are placed in a beaker Mix 200 g of demineralized water and heat the solution to approx. 45 ° C. For this 160 g of cold 50% sodium silicate solution are added, whereby a temperature of approx. 40 ° C. Now the liquid wall material required for encapsulation is created preformed and then 240 g of Mn02 chlorinated paraffin paste with vigorous stirring registered. The internal phase can be reduced to a relative degree via the stirring speed uniform particle size of 300 - 1200 for emulsifying.

After the capsule spectrum has been set, it is cooled to 290C, whereby the wall formation takes place. A dropping funnel is used to make 800 g of saturated Sodium sulfate solution was added dropwise to agglomerate during the subsequent hardening to avoid the microcapsules. The capsule walls are treated with 10 g of formaldehyde for 30 minutes hardened, decanted, and the microcapsules with saturated sodium sulfate solution Washed 5 times. The microcapsules are then placed in a Buchner funnel filtered off, the capsule cake divided and dried on a sieve in a stream of air.

Example 7: 200 g of PbO2 pigment are mixed with 200 g of silicone oil of the specific Weight 0.96-0.97 g / ml at 250C and a viscosity from 240 cP at 25 0C mixed with the help of a friction disc and to achieve a sufficient Homogeneity and pH stability rubbed twice on the three-roll mill. Storage tests showed that this PbO2 silicone oil system over a period of more than 3 months has sufficient pH stability for encapsulation.

200 g of this mixture were made according to that described in Example 1 Encapsulated method, with a relatively narrow capsule range between 200 and 1200 / Am.

Example 8: 200 g of Pb02 pigment are mixed with 300 g of silicone oil of the specific Weight 0.97 g / ml at 25 ° C and a viscosity of approx. 58,000 cP at 25 ° C by hand pasted and 0.2 g of a fluorinated surfactant (F-170 from 3-M-Company) underwent. After the mixture has been rubbed off 4 times on the three-roller mill, it has this uniformity and pH stability sufficient for microencapsulation.

180 g of an 11% gelatin solution of a gelatin are used for microencapsulation of 285-305 bloom-grams and an isoelectric point at pH = 8 - 9 and 180 g 11% gum arabic Solution with 1500 ml of demineralized Mixed water and then 80 ml of a 2% strength poly-ethylene maleic anhydride copolymer solution admitted. This solvent mixture is heated to about 50 ° -550 ° C., whereby adjusts a pH value of 5.3. This solution is set with stirring 350 g of the like The Pb02 silicone oil paste produced above is added and emulsified. This Pb02 silicone oil system is comparatively difficult to emulsify, so that a very broad spectrum of capsules from approx. 20 - 2000) & m. The emulsion becomes slow after emulsifying cooled to 280C, during which the coacervation takes place. Then, while stirring cooled quickly to 5-10 ° C., added 20 ml of glutaraldehyde and continued stirring for 16 hours, in the course of which the temperature rises to room temperature. The microcapsules are then washed, isolated and dried according to the example.

Example 9: 200 g of Pb02 pigment are mixed with 160 g of perfluoropolypropylene oxide (FOMBLIN Y04 from Montedison) with a specific weight of 1.87 g / ml at 200C and a viscosity of 35 aSt at 200C using a friction disk and then made into a paste Rubbed 3 times on the three-roller mill. Storage tests of the scraper showed that there is sufficient homogeneity and pH stability over several for microencapsulation months was guaranteed.

The microencapsulation was initially carried out according to Example 8.

After the capsule suspension has cooled to a temperature of 5 -80C However, another 80 ml of the 2% strength solution of the polyethylene maleic anhydride copolymer were used was added and the pH was adjusted to 9-1 using 25% NaOH solution. Then 10 ml of formaldehyde are added and stirring is continued for 16 hours; while during this time the temperature rises to room temperature. The microcapsules are then washed according to Example 1, isolated and dried. The so produced Microcapsules show no sedimentation even after a year of storage in the internal phase.

Example 10: 200 g of Pb02 pigment are mixed with 200 g of perfluoropolypropylene oxide (KRYTOX from duPont) with a specific weight of 1.91 g / ml at 200 ° C. and a viscosity of 285 cSt at 37.80C pasted by hand and this paste 4 times on the three-roll mill Abraded with a very narrow gap. The scraper showed even after several months Storage still sufficient homogeneity and hydrolysis stability for microencapsulation.

250 g of the PbO2-KRYTOX mixture prepared as above were obtained according to Example 8 encapsulated and then according to Example 2 for the shrinkage of the microcapsules aftertreated with sodium sulfate. The microcapsules produced according to the invention leave no sedimentation in the internal phase even after one year of storage recognize.

Example 11: 200 g of zinc oxide are mixed with 300 g of silicone oil from the specific Weight 0.96-0.97 g / ml at 25 ° C and a viscosity of 240 cP at 250C during Stirred for 5 minutes, then subjected to 0.1 g of a fluorinated surfactant and 100 g silicone oil with a specific gravity of 0.97 g / ml and a viscosity of 58,000 cP incorporated by hand. This paste is applied 3 times on the three-roll mill rubbed off and the homogeneous, pH-stable scraper encapsulated as follows: 180 g 11 % gelatin solution and 180 g 11% gum arabic solution are each with 40 ml of a 2% solution of two ethylene maleic acid copyders, each of which is different Molecular weight (EMA 843-21 and EMA 843-31) mixed and with 1000 ml of demineralized Water diluted.

The temperature is set to approx. 36-400C, 300 g ZnO silicone oil paste added and emulsified until a capsule spectrum of approx. 300 - 1400 ohm arises. At pH 6.8, the mixture is stirred to approx.

280C cooled. The temperature then increases as quickly as possible lowered to 5-100C, 24 ml glutaraldehyde added and the microcapsules as below Example 1 cured, washed, separated and dried.

Example 12: 200 g of manganese IV oxide pigment are mixed with 150 g of silicone oil with a specific gravity of 0.97 glml at 250C and a viscosity of 58,000 cP 250C for 5 min. Pasted with a slowly rotating friction disc, 0.25 g of Turkish red oil added and incorporated for 2 minutes. This mixture is then 4 times on the Three-roller mill abraded, with a homogeneous distribution of the pigment in the carrier phase he follows. To adjust the encapsulation viscosity, 250 g of silicone oil are from specific gravity 0.96-0.97 g / ml and a viscosity of 240 cP at 25 0C added and the mixture rubbed off again with the smallest gap width. That MnO2-silicone mixture produced in this way still shows after several encapsulation Months of perfect pH stability.

Example 13: 200 g of manganese IV oxide pigment are mixed with 300 g of perfluoropolypropylene oxide (FOMBLIN YR from Montedison) with a specific weight of 1.91 g / ml at 20 ° C and a viscosity of 493 cSt at 37.80C using a friction disk and rubbed off 3 times on the three-roller mill for homogenization. The scraper has pH stability sufficient for microencapsulation for several months. The encapsulation according to Example 6, storage-stable microcapsules are obtained which, even after a long period of time, do not contain any Show signs of sedimentation in the internal phase.

Example 14: 200 g of zinc oxide are mixed with 300 g of perfluoropolypropylene oxide (FOMBLIN YR) with a specific weight of 1.91 g / ml at 200C and a viscosity of 493 cSt at 37.80C with the help of a friction disc and then at the lowest Gap width rubbed off 5 times. Storage tests of this paste showed that the microencapsulation required homogeneity and hydrolysis resistance guaranteed for approx. 1 month remains and a satisfactory microencapsulation according to Example 9 is possible.

Example 15: 200 g of zinc oxide pigment are mixed with 350 g of mercaptopropyltrimethoxysilane with a specific gravity of 1.05 g / ml at 200C and a viscosity of 1.5 cSt 2o0C intimately mixed using a stirrer and this mixture 3 times on a three-roll mill rubbed off. This creates a homogeneous system that is encapsulated as follows: 300 g of a 10% gelatin solution are mixed with 300 g of demineralized water mixed, the solution heated to 500C and 240 g of a 50% strength cabbage silicate solution admitted. The wall material required for encapsulation is preformed and then 300 g of the ZnO paste prepared as described above were added. The internal phase can be surprisingly uniform due to the spontaneous wrapping Emulsify particle sizes of approx. 400 - 1200 m. Then it is very slowly on Cooled 27 0C and slowly using a dropping funnel 1200 ml of a 15% aqueous sodium sulfate solution was added dropwise.

The capsule walls are then, with constant stirring, within a Hardened hour with 30 ml formaldehyde. The hardened microcapsules are used several times Washed with 15% Na2S04 solution, the wash water in each case by decanting Will get removed. Finally, the microcapsules by filtration separated, the capsule cake divided and dried on a sieve in an air stream.

Patent claims:

Claims (8)

Claims: 1. Microcapsules with a content of oxidic metal compounds of electropositive bivalent and tetravalent metals of the II. and IV. main and subgroups and the VII. subgroup of the periodic table, especially for use as Polymerization hardener or vulcanization aid, characterized in that the metal compounds contained in the microcapsules a water repellent wear. 2. Microcapsules according to claim 1, characterized by a Content of a plasticizer. Microcapsules according to claim 2, characterized in that the Water repellant has a higher specific weight than the plasticizer. 4. A method for producing the microcapsules according to one of the claims 1 to 3 with a content of oxidic metal compounds of the electropositive two- and tetravalent metals of the II. and IV. main and sub-group and the VII. sub-group of the periodic table, characterized in that the metal compound before microencapsulation is treated with a water repellent. 5. The method according to claim 4, characterized in that as Metal compound lead IV oxide, manganese IV oxide and zinc II oxide is used. 6. The method according to claim 4 or 5, characterized in that that as hydrophobizing agents halogen paraffins, especially chlorinated paraffin, perfluoropolypropylene oxides, Silicone oils and silanes can be used. 7. The method according to any one of claims 4 to 6, characterized in that that a hydrophobizing agent, preferably chlorinated paraffin with a specific Weight greater than 1.2 g / ml and a viscosity greater than 1000 cP is used. 8. The method according to any one of claims 4 to 7, characterized in that that a surface-active substance, preferably a fluorinated carboxylic or sulfonic acid, in particular turkish red oil is incorporated into the internal phase.