Process for making synthetic paper pulp

Claim 1

A process for preparing synthetic paper comprising: (a) heating a blend consisting essentially of a synthetic thermoplastic polymer wherein the polymer is a mixture of polystyrene and polypropylene or polyethylene in which the mixture contains more than 40 percent by weight of the polypropylene or polyethylene and the blend contains from about 0.1 to about 20 percent weight of sodium bicarbonate and whereby a molten blend is formed; (b) extruding the molten blend from a die into a zone of reduced pressure to produce an extrudate; (c) attenuating the extrudate while the polymer is in its molten or amorphous state with the attenuation caused by withdrawing the extrudate from the die at a linear rate of from about 20 to about 200 times the linear ratio at which the blend reaches the lips of the die; (d) subjecting the attenuated extrudate, which is now fibrous and solid, to sufficient force to cause the extrudate to break into fibers suitable for mixing with cellulosic pulp; and (e) the resulting fibers, in an amount of about 10 to 50 weight % of the total weight, are mixed with bleached kraft paper fibers laid out in a sheet and formed into a paper by application of heat and pressure.