Process for production of powder redispersible in water and use thereof
View Patent ↗The present invention relates to a process for the production of powders redispersible in water comprising an organic component and a water-soluble organic polymeric protective colloid. The organic component is dispersed and stabilized with the protective colloid in water to form a stable dispersion which is dried to form the powder redispersible in water. The organic component comprises abietic acid, sylvic acid, neoabietic acid, levopinaric acid, pimaric acid, isopimaric acid and/or palustric acid and/or their derivatives. The water-soluble organic polymeric protective colloid comprises synthetic protective colloids and naturally and/or synthetically produced biopolymer which can be synthetically modified. The obtained powder reduces efflorescence in hydraulically set systems.
1. Process for the production of powder redispersible in water, said powder comprising: an organic component, a water-soluble organic polymeric protective colloid and, optionally, one or more further additives,
wherein the organic component contains at least one compound with a cyclic group, the cyclic group being completely or partially saturated and having a melting point of approximately −20 to 250° C. and a molecular weight of about 100 to 10,000, and the organic component further contains a terpeneoid, a resin acid, colophony, terpene resin, terpene-phenol resin and/or their derivatives, and
wherein the water-soluble organic polymeric protective colloid has a content of monocarboxylic acid and dicarboxylic acid as well as their anhydrides of less than 50 mole %, and not consisting of aromatic sulfonic acid condensates, and
said process comprising the steps of:
dispersing the organic component in water to obtain an aqueous dispersion,
stabilizing the aqueous dispersion with the water-soluble organic polymeric protective colloid, wherein the weight ratio of the organic component to the water-soluble organic polymeric protective colloid is 95:5 to 5:95, and
drying the aqueous dispersion by spray drying, freeze drying, and/or fluid bed drying, thereby forming the redispersible powder.
2. The process according to claim 1 characterised in that the solids content of the stabilized dispersion is 10 to 75% by weight and the average particle size of the dispersed particles to 0.05 to 50 μm.
3. The process according to claim 1 wherein further liquid and/or water-soluble additives are added before, during or after formation of the dispersion, and further additives in powder form are added during or after drying.
4. The process according to claim 1 further comprising the step of mixing the obtained redispersible powder with film-forming dispersion powders redispersible in water, redispersible hydrophobing agents in powder form based on silanes, siloxanes, silicones, fatty acids and/or fatty acid esters and/or polysaccharide ethers.
5. The process according to claim 1 wherein the aqueous dispersion is dried jointly with at least one other dispersion based on film-forming polymers and/or silanes, silane esters, siloxanes, silicones, fatty acids and/or fatty acid esters, wherein the dispersions are mixed with each other before drying or sprayed separately and subsequently dried jointly.
6. The process according to claim 5 wherein the aqueous dispersion is stabilised by emulsifiers and the at least one other dispersion comprises an excess of water-soluble organic polymeric protective colloid in water, the water-soluble organic polymeric protective colloid having a content of monocarboxylic and dicarboxylic acids and their anhydrides of less than 50 mole % and not consisting of aromatic sulfonic acid condensates.
7. Powder redispersible in water obtained from the process according to claim 6 .
8. The process according to claim 1 characterised in that the cyclic group of the organic component is a monocyclic, dicyclic, tricyclic, tetracyclic and/or pentacyclic group.
9. The process according to claim 1 characterised in that the organic component is a natural product selected from the group consisting of a monoterpene, sesquiterpene, diterpene, sesterterpene, triterpene, tetraterpene, polyterpene and their derivatives.
10. The process according to claim 1 characterised in that the organic component is at least one compound with at least one carboxyl group, carbonyl group, aldehyde group and/or alcohol group.
11. The process according to claim 1 characterised in that the organic component is abietic acid, sylvic acid, neoabietic acid, levopinaric acid, pimaric acid, isopimaric acid and/or palustric acid and/or their derivatives.
12. The process according to claim 1 characterised in that the organic component is not soluble in acidic to neutral water.
13. The process according to claim 1 characterised in that the water-soluble organic polymeric protective colloid representing a synthetic protective colloid is a modified and/or unmodified polyvinyl alcohol with a degree of hydrolysis of 70 to 100 mole % and a Höppler viscosity, as 4% aqueous solution, of 1 to 50 mPas, measured at 20° C. according to DIN 53015, and/or polyvinyl pyrrolidone.
14. The process according to claim 1 characterised in that the solids content of the dispersion of the organic component stabilised with the water-soluble organic polymeric protective colloid amounts to 25 to 65% by weight and the average particle size of the dispersed particles is 0.1 to 20 μm.