Functionalized particulate bicarbonate as blowing agent, foamable polymer compositon containing it, and its use in manufacturing a thermoplastic foamed polymer

Abstract

A chemical blowing agent for foaming a thermoplastic polymer, for example PVC plastisol or a polymer resin in an extrusion process, said chemical blowing agent comprising a functionalized particulate bicarbonate containing at least one additive, preferably excluding an exothermic blowing agent. The additive may be selected from the group consisting of polymers; inorganic salts; oils; fats; resin acids, any derivative thereof, and salts thereof; amino acids; fatty acids; carboxylic or polycarboxylic acids, soaps; waxes; in derivatives thereof (such as esters); salts thereof; or any combinations thereof. The particulate bicarbonate may be functionalized by spray-drying, coating, extrusion or co-grinding with at least one additive. The functionalized particulate bicarbonate may comprise 50 wt % to less than 100 wt % of the bicarbonate component, and 0.02-50 wt % of the additive. A foamable polymer composition comprising such chemical blowing agent. A process for manufacturing a foamed polymer, such as foamed PVC, comprising shaping and heating the foamable polymer composition, and a foamed polymer obtained by such process.

We claim: 
     
         1 .- 31 . (canceled) 
     
     
         32 . A method, comprising: foaming a thermoplastic polymer precursor with a chemical blowing agent, wherein said chemical blowing agent comprising a functionalized particulate bicarbonate containing at least one additive chosen from the following compounds:
 one or more polymers;   one or more amino acids, any derivative thereof, and salts thereof;   one or more inorganic salts;   one or more oils;   one or more fats;   one or more resin acids, any derivative thereof, and salts thereof;   one or more fatty acids, any derivative thereof, and salts thereof;   a carboxylic or polycarboxylic acid, derivative thereof (such as esters), or salts thereof;   one or more soaps;   one or more waxes; or   any combinations thereof,   wherein the functionalized particulate bicarbonate comprises sodium bicarbonate,   wherein the functionalized particulate bicarbonate comprises at least 65% by weight and less than 100% by weight of sodium bicarbonate and from 0.02% to 35% by weight of said at least one additive.   
     
     
         33 . The method according to  claim 32 , wherein the blowing agent does not contain any further blowing agent which is an exothermic blowing agent. 
     
     
         34 . The method according to  claim 32 , wherein the chemical blowing agent does not contain a compound which liberates nitrogen gas during heating. 
     
     
         35 . The method according to  claim 32 , wherein the blowing agent does not contain a compound which liberates ammonia gas during heating. 
     
     
         36 . The method according to  claim 32 , wherein the additive in the functionalized particulate bicarbonate is
 a) at least one compound selected from the group consisting of an amino acid, derivative thereof, or salt thereof, wherein the amino acid is selected from the group consisting of casein, gelatin, glycine, proline, hydroxyproline, glutamic acid, alanine, arginine, aspartic acid, lysine, pectin, serine, leucine, valine, phenylalanine, threonine, isoleucine, hydroxylysine, methionine, histidine, tyrosine, and combinations thereof;   b) at least one compound selected from the group consisting of a fatty acid, derivative thereof, or salt thereof, wherein the fatty acid is at least one compound selected from the group consisting of lauric acid, stearic acid, glycerol mono stearate, and combinations thereof;   c) at least one polymer selected from the group consisting of polyoxyalkylenes and derivatives thereof including polyethylene glycols, poly(meth)acrylates and derivatives thereof, polyvinylalcohol, polysaccharides, and combinations thereof, wherein the polymer selected from the group consisting of polyvinylalcohol and polyoxyalkylenes and derivatives thereof including polyethylene glycols; wherein the polysaccharides are selected from the group consisting of modified, in particular hydrolyzed starch, maltodextrin, arabic gum and combinations thereof;   d) at least one resin acid, any derivative thereof, and salts thereof;   e) at least one oil, wherein the oil is a vegetable oil or any derivative thereof; or   f) at least one wax selected from the group consisting of beeswax, carnauba wax and combinations thereof.   
     
     
         37 . The method according to  claim 36 , wherein the amino acid is leucine. 
     
     
         38 . The method according to  claim 36 , wherein the amino acid is lauric acid. 
     
     
         39 . The method according to  claim 36 , wherein the polysaccharide is maltodextrin. 
     
     
         40 . The method according to  claim 36 , wherein the resin acid is rosin acid. 
     
     
         41 . The method according to  claim 36 , wherein the oil is epoxidized soy bean oil. 
     
     
         42 . The method according to  claim 32 , wherein particles of the functionalized particulate bicarbonate have a particle size distribution of D50 of more than 1 and at most 250 μm 
     
     
         43 . The method according to  claim 32 , wherein particles of the functionalized particulate bicarbonate have a particle size distribution of D50 of at most 1 μm. 
     
     
         44 . The method according to  claim 32 , wherein the functionalized particulate bicarbonate is obtained by at least one of the following processes:
 by spray-drying (also known as atomization), wherein the additive is dissolved in the bicarbonate-containing solution;   by grinding or co-grinding (also known as milling or co-milling) with the additive(s) in emulsion or powder form;   by spray coating and granulation within a fluidized bed;   by spray agglomeration within a fluidized bed;   by spray chilling, wherein the spray chilling comprises spray cooling or spray freezing;   by roller compaction; and/or   by extrusion, including simultaneous mixing/extrusion.   
     
     
         45 . The method according to  claim 39 , wherein the functionalized particulate is further subjected to milling to reduce its mean particle size. 
     
     
         46 . The method according to  claim 32 , wherein the foaming step further comprises a second compound which liberates CO 2  upon heating, said second compound being selected from the group consisting of a carboxylic or polycarboxylic acid, derivative thereof, or salts thereof, wherein said second compound is functionalized with at least one additive which is different or same as the one in the functionalized particulate bicarbonate. 
     
     
         47 . The method according to  claim 46 , wherein said second compound is at least one of:
 fumaric acid,   tartaric acid,   citric acid, citrates, or esters of citric acid; or combination thereof.   
     
     
         48 . The method according to  claim 32 , wherein the foaming foams a foamable polymer composition comprises a polymer, optionally a foaming stabilizer, and the chemical blowing agent, wherein the polymer is a PVC, a polyurethane, a polyolefin, or a polyamide. 
     
     
         49 . The method according to  claim 32 , wherein the foaming foams a foamable PVC plastisol composition, comprising a PVC resin, optionally a foaming stabilizer, and the chemical blowing agent, which does not contain azodicarbonamide, benzenesulfonylhydrazide, and/or p-toluenesulfonylhydrazide.