| 摘要 |
PROBLEM TO BE SOLVED: To obtain a filter plate having excellent mechanical strength and high durability. SOLUTION: In a filter plate, a plurality of columnar, oval, long bank-shaped or lattice-shaped filter groove forming projections are provided on the surface of a substrate based on a crystalline polypropylene or polyethylene resin so as to leave the base parts thereof and the diameter of the spherical crystals of the resin of the root parts of the projections is 30-70μm in a crystalline polypropylene resin and 3-10μm in a crystalline polyethylene resin. This filter plate is produced by using the plate-shaped substrate of a crystalline polyolefinic resin to melt the max. height parts of the projections to be shaped or the regions from the surface of the substrate corresponding to 1.4 times the max. height of the projections at plastically flowable temp. and subsequently compressing and shaping the substrate in the molten state by a mold and passing a cooling medium through the mold to cool the molded substrate to form a plurality of columnar, oval, long bank-shaped or lattice-shaped filter groove forming projections on the surface of the substrate so as to leave the base parts thereof.
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