| 摘要 |
Two-grade filtering cloth consisting of two layers of different texture and fibre diameter, joined together by needling, in which the layer with higher porosity and fibre diameter constitutes a pre-filter, while the layer with lower porosity and fibre diameter constitutes a proper filter characterised in that bundles of fibres which are taken, with the use of a needle, from the higher porosity layer, are fastened in the smaller porosity layer of lower porosity on the depth not exceeding 17/18 of thickness of such a layer, creating in it some additional inter-fibre pores and channels, and the proportion between fibre diameter from individual layers is at least 1:12, the product's mass density is not higher than 0.08 g/cm<3>, and mass share of the lower porosity layer in the total product mass is at least 50%.
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