| 摘要 |
PURPOSE:To obtain the titled material suitable for use for a large scale units and having improved collecting efficiency and pressure drop, and also a good strength by making the titled filter from the fibrous layer composed of a very fine glass fiber and a fibrous binder, and the fibrous layer composed of a syn thetic fiber and the fibrous binder. CONSTITUTION:The fibrous layer having 10-120g/(m)<2> basis weight is formed of 95-100% of very fine glass fiber having <=4mu diameter and 5-0% of PVA fibrous binder. And, the another fibrous layer having 10-80g/(m)<2> basis weight is formed of 80-100% of synthetic fiber such as the PVA fiber, etc., having 0.05-3 denier the fineness and >=90 deg.C the dissolution temp. in water and 20-0% of PVA fibrous binder. Said fiber layers are made to a sheet in such a structure that each of said layers are laminated with each other or said synthetic fiber layer is inserted between said glass fiber layers. The PVA fibrous binder has preferably 500-2,500 polymerization degree and >=85mol% saponification value, 45-90 deg.C dissolution temp. in water, 0.3-10 denier fineness and 1-10mm fiber length.
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