Abstract: Polypropylene films which have cavities distributed in the film and on the surfaces are suitable for writing or printing and have a low density. The films have surface qualities of each side of surface within .+-.2.times.10.sup.-6 inch of the average depth of the cavities, .+-.2% of the average of the gloss at 45.degree. angle and .+-.0.02 of the average of coefficient of friction. Such a film is obtained by passing the molded film from the calender through a set of heating rolls at temperatures revealed in this invention before entering the stretching system. The obtained polypropylene film has superior printability, low density and high stiffness, and thus is suitable for use as a paper substitute.

Abstract: A process which combines a calender with a stretching system and a set of heating rolls is provided in this invention to produce films of polypropylene resin of wide thickness range. The polypropylene films which have cavities distributed in the film and on the surfaces are suitable for writing or printing and have a low density. The films have surface qualities of each side of surface within .+-.2.times.10.sup.-6 inch of the average depth of the cavities, .+-.2% of the average of the gloss at 45.degree. angle and .+-.0.02 of the average of coefficient of friction. Such a film is obtained by passing the molded film from the calender through a set of heating rolls at temperatures revealed in this invention before entering the stretching system. The obtained polypropylene film has superior printability, low density and high stiffness, and thus is suitable for use as a paper substitute.

Abstract: The present invention relates to a blown film forming composition which improves the clarity, haze and gloss while improving or maintaining the mechanical properties of the high density polyethylene film. The film forming composition includes about 50 to about 99% by weight of an ethylene polymer of density in the range of about 0.940 g/cm.sup.3 to about 0.970 g/cm.sup.3 and a melt index of no more than 1.0 g/10 min. measured at 190.degree. C. and 5 Kg load and about 50 to about 1% by weight of an additive consisting of (a) about 10 to 100% of a plastomer-type ethylene polymer of density in the range of about 0.900 to about 0.920 g/cm.sup.3 and of melt index from about 0.1 to about 10 g per 10 minutes, and (b) about 90 to 0% of a copolymer of ethylene and vinyl acetate of density from about 0.910 to about 0.940 g/cm.sup.3 and of melt index ranging between about 0.1 and about 10 g/10 min.

Abstract: An extruded hollow plastic board is described which has a pair of flat and parallel sheets spaced apart and interconnected by longitudinally extending ribs. The ribs and sheets are connected with rounded joint areas, which significantly improve the mechanical properties and solve undercut and die line problems existing with prior art hollow plastic boards. This invention also provides a method for the manufacture of the hollow board of thermoplastic resin thereof.

Abstract: A method for manufacturing automatic consecutively opened thermoplastic T-shirt bags for dispensing from a conventional supporting rack. The method involves providing a continuous flattened tube of thermoplastic film and applying adhesive solution using a printing press to form adhesion regions on the outside of the tube. The adhesive solution can be applied using a flexo or gravure printing process. The method then involves forming side gussets in the tube and making traverse seals in the tube, thereby dividing the tube into pillowcases. The pillowcases are separated at the seals to form a series of end-sealed gussetted pillowcases which are stacked to form a bag pack. Next, the bag pack is cut along a bag-mouth contour to from a plurality of T-shirt bags. The bag-mouth contour forms a set of laterally spaced handles each having a receiving aperture for a conventional support rod of a dispensing rack, a central tab having a mounting aperture, and an open mouth region.

Abstract: The present invention is directed at polypropylene compositions containing a high level of filler, at a calendering process which uses the compositions to produce polypropylene films and sheets, and at the film or sheet produced from that process. The process of manufacturing polypropylene film involves formulating a polypropylene composition containing a resin, filler, matrix modifier, and processing aid. The resin comprises polypropylene resin ranging in concentration from about 100 to about 70 parts per hundred parts by weight of resin (PHR), and polyethylene resin ranging in concentration from about 0 to 30 PHR. The matrix modifier amounts to about 2 to 40 PHR. The filler ranges in concentration from about 0 to 450 PHR. The processing aid ranges in concentration for about 0 to 5.0 PHR. The composition is then mixed to obtain a homogeneous and plasticized mixture.