Plastisol blowing agent

Foams are made by the addition of blowing agents to the plastisol. These may be continuously applied to a moving substrate which includes a pass at an elevated temperature where foaming occurs, followed by fusion of the plastisol. 

Syntactic foams are made using a resin matrix to which has been added hollow spheres of various materials. The resultant product is a foamlike material made without the use of a blowing agent. The most common matrix resins are epoxies and polyesters, although urethanes, PVC plastisols, and phenolic resins have also been used. Indeed, any polymer that can be made liquid, either before final polymerization or by heat, can be used as the binding resin. In syntactic foams the resin matrix is the continuous phase and the hollow spheres the discontinuous phase. 

Mechanical incorporation of air into the paste or the use of chemical "blowing agents" into the formulations allows foam products to be produced. Plastisols are not "air-dry" systems that is, they require fusion temperatures of at least 250 °F for the copolymers and 300 °F for the homopolymers. 

The 100% solid system of plastisols allows very thick coating weights to be applied. Because Increased plasticizer lowers viscosity and assists in coating application, very high plasticizer levels (for very soft films) are easily handled. The use of chemical blowing agents and mechanical air incorporation are easily adaptable to plastisol systems. 

The development of hollow thermoplastic microspheres has offered the prospect of lower density plastisols with superior physical properties and appearance than have been attainable by other known techniques. Such microspheres have become available, having, for example, diameters on the order of 10 to 200 im, most often 20 to 100 pm, and densities of 0.06 to 0.02 g/cm, or even as low as 0.015 g/cm. The thermoplastic material of which the microspheres are formed is typically a polyvinylidene chloride or a copolymer of polyvinylidene chloride with other vinyl or acrylic monomers, such as acrylonitrile, butylene, and the like. The hollow microspheres contain a physical blowing agent, typically a lower alkane, most often a butane or pentane, or their mixtures. A variety of such materials are commercially available. 

Uses Blowing agent in PU (footwear, sporting goods), PVC plastisols (automotive undercoatings), printing ink, fabrics, paper and board,... 

Uses Blowing agent in printing inks, PU, PVC plastisols, fabrics, paper expanded microspheres as ultra-low density tillers tor use in engineered prods, in which other fillers would not be suitable, e.g., syn. marble and wood, coatings, sealants, explosives, auto, marine fillers, molding compds., composites, paint and crack fillers, cable fillings, elastomers Features Unexpanded microspheres Expancel 551 DE 20 [Expancel]... 

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