Plastisol having a high rubber content

Abstract

This invention is based upon the unexpected discovery that aliphatic solvents and secondary plasticizers act to reduce the viscosity of plastisol compositions that contain a crosslinked nitrile rubber. It has been unexpectedly found that plastisol compositions having acceptable viscosities which contain more than 30 or even 40 percent crosslinked nitrile rubber can be made by incorporating an aliphatic solvent or an aliphatic plasticizer therein. This invention more specifically discloses a plastisol composition which is comprised of (i) polyvinyl chloride, (ii) optionally, from about 60 to about 100 parts by weight of a primary plasticizer per 100 parts by weight of the polyvinyl chloride, (iii) from about 1 to about 3 parts of a stabilizer per 100 parts by weight of the polyvinyl chloride, (iv) from about 2 to about 100 parts of an aliphatic solvent or a secondary plasticizer per 100 parts by weight of the polyvinyl chloride and (v) from about 20 to about 50 parts by weight of a powdered crosslinked nitrile rubber per 100 parts of the polyvinyl chloride, wherein the powdered crosslinked nitrile rubber is comprised of repeat units which are derived from (a) 1,3-butadiene, (b) acrylonitrile and (c) a crosslinking agent, wherein said powdered crosslinked nitrile rubber has a Mooney viscosity which is within the range of about 50 to about 120, a swelling index of less than about 20 percent, a mill shrinkage of less than about 30 percent, a gel content of greater than 80 percent and a particle size of no greater than about 250 microns.