Microcapsules

Abstract

The present invention concerns microcapsules comprising a capsule core, a capsule wall and also, disposed on the outer surface of the capsule wall, a polyelectrolyte having an average molecular weight in the range from 500 g/mol to 10 million g/mol, the capsule wall being constructed from 10% to 100% by weight of one or more C 1 -C 24 -alkyl esters of acrylic and/or methacrylic acid (monomers I), 0% to 80% by weight of a water-insoluble or sparingly soluble in water bi- or polyfunctional monomer (monomers II), and 0% to 90% by weight of other monomers (monomer Ill) all based on the total weight of the monomers, wherein the microcapsules have an average particle size of 1.5-2.5 μm and 90% of the particles have a particle size ≦4 μm, a process for their production, their use in textiles, bindered building materials and heat transfer fluids, and also microcapsules as an intermediate product.

1 - 18 . (canceled) 
     
     
         19 . Microcapsules comprising a capsule core and a polymeric capsule wall formed from the following monomers:
 10% to 100% by weight of at least one C 1 -C 24 -alkyl esters of acrylic and/or methacrylic acid (monomers I),   5% to 60% by weight of a water-insoluble or sparingly water-soluble bi- or polyfunctional monomer (monomers II), and   0% to 85% by weight of other monomers (monomer III),   all based on the total weight of the monomers, wherein the microcapsules have an average particle size of 1.5-2.5 μm and 90% of the particles have a particle size ≦4 μm,   and obtained by a process comprising:   a) preparing an oil-in-water emulsion comprising the monomers, the lipophilic substance and polyvinyl alcohol and/or partially hydrolyzed polyvinyl acetate, the average size of the oil droplets being 1.5-2.5 μm, and   b) free-radically polymerizing the monomers of the oil-in-water emulsion obtained from a),   wherein the polyvinyl alcohol and/or partially hydrolyzed polyvinyl acetate has a viscosity in the range of 22-41 mPa·s.   
     
     
         20 . The microcapsules of  claim 19 , which are obtained by a method comprising:
 (a) microencapsulating a capsule core with a polymeric capsule wall by the polymerization of the following monomers:
 (i) 10% to 100% by weight of one or more C 1 -C 24 -alkyl ester of acrylic and/or methacrylic acid, 
 (ii) 0% to 80% by weight of a water-insoluble or sparingly water-soluble bi- or polyfunctional monomer, and 
 (iii) 0% to 90% by weight of other monomers, 
   all based on the total weight of the monomers,   
       to produce the microcapsules. 
     
     
         21 . The microcapsules of  claim 19 , which are obtained by a method comprising:
 (a) microencapsulating a capsule core with a polymeric capsule wall by the polymerization of the following monomers:
 (i) 10% to 100% by weight of one or more C 1 -C 24 -alkyl ester of acrylic and/or methacrylic acid, 
 (ii) 0% to 80% by weight of a water-insoluble or sparingly water-soluble bi- or polyfunctional monomer, and 
 (iii) 0% to 90% by weight of other monomers, 
   all based on the total weight of the monomers,   
       to produce microcapsules; 
       followed by
 (b) drying the microcapsules. 
 
     
     
         22 . The microcapsules of  claim 19 , wherein the capsule core is a lipophilic substance having a solid/liquid phase transition in the temperature range from −20 to 120° C. 
     
     
         23 . The microcapsules of  claim 19 , which have an average particle size of 1.7-2.4 μm. 
     
     
         24 . The microcapsules of  claim 19 , wherein 90% of the microcapsules have a particle size ≦3.5 μm. 
     
     
         25 . The microcapsules of  claim 19 , wherein 90% of the microcapsules have a particle size ≦3 μm. 
     
     
         26 . The microcapsules of  claim 19 , wherein the full width at half maximum value of the microcapsule dispersion is 0.2 to 1.5. 
     
     
         27 . The microcapsules of  claim 19 , wherein the full width at half maximum value of the microcapsule dispersion is 0.4 to 1.0. 
     
     
         28 . The microcapsules of  claim 19 , wherein the weight ratio of the capsule core to the capsule wall is 50:50 to 95:5. 
     
     
         29 . The microcapsules of  claim 19 , wherein the weight ratio of the capsule core to the capsule wall is 70:30 to 93:7. 
     
     
         30 . A textile having incorporated therein the microcapsules of  claim 19 . 
     
     
         31 . A hindered building material comprising the microcapsules of  claim 19 . 
     
     
         32 . A heat transfer fluid comprising a dispersion of the microcapsules of  claim 19 . 
     
     
         33 . A method of preparing microcapsules,
 wherein the microcapsules comprise a capsule core and a polymeric capsule wall, wherein   (1) the polymeric capsule wall is formed from units obtained by the polymerization of the following monomers:
 10% to 100% by weight of at least one C 1 -C 24 -alkyl ester of acrylic and/or methacrylic acid, 
 0% to 80% by weight of a water-insoluble or sparingly water-soluble bi- or polyfunctional monomer, and 
 0% to 90% by weight of other monomers, 
 all based on the total weight of the monomers, 
   (2) the microcapsules contain from 0.1% to 10% by weight of the polyelectrolyte based on the total weight of the microcapsules,   (3) the microcapsules have an average particle size of 1.5-2.5 μm, and   (4) 90% of the microcapsules have a particle size ≦4 μm, comprising:   (a) microencapsulating a capsule core with a polymeric capsule wall formed from the polymerization of the following monomers:
 (i) 10% to 100% by weight of one or more C 1 -C 24 -alkyl ester of acrylic and/or methacrylic acid, 
 (ii) 0% to 80% by weight of a water-insoluble or sparingly water-soluble bi- or polyfunctional monomer, and 
 (iii) 0% to 90% by weight of other monomers, 
   all based on the total weight of the monomers,   
       to produce microcapsules. 
     
     
         34 . The method of  claim 33 , further comprising (c) isolating the microcapsules 
     
     
         35 . The method of  claim 33 , further comprising (c) drying the microcapsules. 
     
     
         36 . The method of  claim 33 , further comprising (c) spray drying the microcapsules.