| 摘要 |
Plastic film and sheet material are provided which have integrally formed surface ribs which are designed to inhibit tears from propagating in one or more selected directions along or across the film or sheet. The ribs may be arranged in laterally spaced parallel rows, or in a criss-cross pattern and may have various cross-sectional shapes. The film or sheet which may be comprised of polyethylene or other suitable plastic material, may be used as drop cloths, tarpaulins, moisture barriers, mulching and soil erosion control material and so on. The film or sheet may be formed by extrusion, co-extrusion, blown film or other plastic forming techniques. Thicknesses of the film or sheet between the ribs may range from about 1 mil (or less) up to about 80 mil, with thicknesses through the ribs of about 3 to about 500 mil.
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