阅读说明：本技术 一种用于立式压滤机的滤布及其制备方法 (Filter cloth for vertical filter press and preparation method thereof ) 是由 毕蕾 王继光 于 2020-06-01 设计创作，主要内容包括：本发明涉及滤布制备工艺,具体的说是一种用于立式压滤机的滤布及其制备方法。滤布由经、纬线交织形成高强低伸基布；再经针刺方式,在基布表层植入至少一层的短纤维网,形成短纤维间隙过滤层；而后通过热压,使表层低熔点纤维熔融挤压,形成小孔径滤膜层的复合滤布。由经、纬向纱线交织形成机织高密基布；在基布表面,以短纤维为原料针刺至少一层的纤维网,进而作为短纤维过滤层,而后通过热压使短纤维间隙过滤层的表层形成滤膜,即形成小孔径滤膜层的复合滤布。本发明中机织高强低伸基布为由经、纬向纱线构成稳定的二维结构,使织物强力高,伸长率小,尺寸稳定性高,满足压滤机对滤布低伸长的要求,保证使用寿命长,过滤效果稳定。(The invention relates to a filter cloth preparation process, in particular to a filter cloth for a vertical filter press and a preparation method thereof. The filter cloth is formed by interweaving warps and wefts into high-strength low-elongation base cloth; then, at least one layer of short fiber net is implanted into the surface layer of the base cloth in a needling mode to form a short fiber gap filtering layer; and then, the low-melting-point fibers on the surface layer are melted and extruded through hot pressing to form the composite filter cloth of the small-aperture filter membrane layer. Weaving high-density base cloth by interweaving warp yarns and weft yarns; at least one layer of fiber net is needled on the surface of the base cloth by taking short fibers as raw materials to serve as a short fiber filtering layer, and then a filtering membrane is formed on the surface layer of the short fiber gap filtering layer through hot pressing, namely the composite filtering cloth of the small-aperture filtering membrane layer is formed. The woven high-strength low-elongation base cloth is a stable two-dimensional structure formed by warp yarns and weft yarns, so that the woven high-strength low-elongation base cloth is high in strength, small in elongation and high in dimensional stability, meets the requirement of a filter press on low elongation of filter cloth, and ensures long service life and stable filtering effect.)

1. A filter cloth for a vertical filter press, characterized in that: the filter cloth is formed by interweaving warps and wefts into high-strength low-elongation base cloth; then, at least one layer of short fiber net is implanted into the surface layer of the base cloth in a needling mode to form a short fiber gap filtering layer; and then, the low-melting-point fibers on the surface layer are melted and extruded through hot pressing to form the composite filter cloth of the small-aperture filter membrane layer.

2. A filter cloth for a vertical filter press according to claim 1, wherein: the short fiber filtering layer is a fiber layer net formed by needling short fibers on the surface of the base fabric from two sides of the base fabric; wherein, the uppermost fiber layer net of the short fiber filter layer is formed by needling fibers with low melting point.

3. A filter cloth for a vertical filter press according to claim 1 or 2, wherein: the short fiber filtering layer is a fiber layer net with more than two layers; wherein the fiber layer net adjacent to the surface of the base cloth is formed by needling of thicker medium long fibers with high melting point, and at least one layer; at least one fiber layer net formed by cotton type fibers with high melting point and thin thickness is arranged between the fiber layer net formed by needling the medium long fibers with high melting point and thick and the fiber layer net formed by needling the fibers containing low melting point.

4. A filter cloth for a vertical filter press according to claim 2, wherein: the high melting point is more than 200 ℃; the low melting point is 110-150 ℃.

5. A filter cloth for a vertical filter press according to claim 2, wherein: the low-melting-point fibers in the uppermost fiber layer of the short fiber filter layer account for 20-100 wt%.

6. A method of preparing a filter cloth for a vertical filter press according to claim 1, wherein: weaving high-density base cloth by interweaving warp yarns and weft yarns; at least one layer of fiber net is needled on the surface of the base cloth by taking short fibers as raw materials to serve as a short fiber filtering layer, and then a filtering membrane is formed on the surface layer of the short fiber gap filtering layer through hot pressing, namely the composite filtering cloth of the small-aperture filtering membrane layer is formed.

7. The method for producing a filter cloth for a vertical filter press according to claim 6, wherein: the woven high-strength low-elongation base cloth is formed by interweaving warps and wefts; wherein the yarn is folded by 300-3000D, the warp density is 200-350 pieces/10 cm, and the weft density is 80-200 pieces/10 cm;

the short fiber filtering layer is a fiber layer net formed by needling short fibers on the surface of the base fabric from two sides of the base fabric; wherein, the uppermost fiber layer net of the short fiber filter layer is formed by needling fibers containing low melting point to form a fiber layer net; the short fiber filtering layer is a fiber layer net with more than two layers; the short fiber filtering layer is a fiber layer net with more than two layers; wherein the fiber layer net adjacent to the surface of the base cloth is formed by needling of thicker medium long fibers with high melting point, and at least one layer; at least one fiber layer net formed by cotton type fibers with high melting point and thin thickness is arranged between the fiber layer net formed by needling the medium long fibers with high melting point and thick and the fiber layer net formed by needling the fibers containing low melting point.

8. The method for producing a filter cloth for a vertical filter press according to claim 6, wherein: the hot pressing temperature is 110-150 ℃ and the pressure is 7-8 Pa; the surface of the short fiber filtering layer is formed into a filtering layer with uniform micro-pore diameter by hot pressing.

9. Use of a filter cloth according to claim 1 for a vertical filter press, wherein: the filter cloth is applied to a vertical filter press for filtering fine materials with the particle size of 25-1 mu m.

The technical field is as follows:

the invention relates to a filter cloth preparation process, in particular to a filter cloth for a vertical filter press and a preparation method thereof.

Background

The vertical filter press is also called as a filter cloth full-walking automatic filter press, and is widely applied to the filtration of products such as nickel concentrate, zinc oxide leachate, enzyme, starch, caustic sludge, zeolite, copper concentrate and the like. The vertical filter press extrudes water in filter residue on the surface layer of the filter cloth through extrusion force so as to reduce the water content in the filter cake. The existing filter press has strict requirements on the strength and deformation rate of the filter cloth due to large tension on the filter press. Most of the filter cloth used for the filter press in the market at present is woven filter cloth.

The woven filter cloth forms interweaving points in a warp-weft interweaving mode, and the interweaving points and yarn gaps are main ways for filtrate permeation. When the interweaving pores are smaller than the grain size of the filter material, the solid particles are blocked at one side of the filter cloth, and the filter effect of the filter cloth is good; when the interweaving pores are larger than the grain size of the filter material, solid particles pass through the interweaving points, so that the filter penetration phenomenon occurs, or the solid particles remain in the filter cloth and are blocked; when the interweaving pores are far smaller than the particle size of the filter material, the water filtering efficiency is low, the water content of the solid filter material is high, and the subsequent processing is inconvenient. Because of the problems, the surface of the woven fabric is treated by adopting heat setting and other methods at present, but the twist-bending degree of yarn interweaving is still remained after the treatment, the surface damage is large under the action of a mechanical scraper, and the surface layer is difficult to clean.

Nonwoven filter fabrics are frequently used in vacuum suction filters, and are formed by laying staple fiber webs in layers to form a fiber-interlaced layer structure. The filtration precision is related to the fiber fineness, the fiber density, the fiber web thickness, the fiber arrangement and the needling process. The multi-layer filtration is realized in the filtration process, and the range of the intercepted particle size is wider. The non-woven product has poor mechanical performance and filtering precision due to easy deformation of the base fabric

Is unstable. In the filtering process, solid materials are easy to remain among fibers, and the cleaning difficulty is high. And the surface fiber of the fabric is easy to fall off and is easy to damage under the action of mechanical external force.

The membrane fabric is mostly applied to gas and liquid filtration, has highest filtration precision, smooth product surface and is very easy to clean. However, high temperature bonding is required when the film is compounded with the substrate, and the application range is limited. The film composite product has long process route and high film making and laminating cost. The membrane product has low strength, large deformation, limited filtering area and filtering pressure, easy damage and short service life, and cannot be applied to filter press equipment.

How to obtain a composite product can make up for the deficiencies of three filter materials, has the advantages of strong weaving strength, small deformation, multi-layer filtering effect of non-woven fabric, and high filtering precision, smooth surface and easy cleaning of film products. The vertical filter press cloth integrating the functions is a problem which needs to be solved urgently in the industry.

Disclosure of Invention

The invention aims to provide a filter cloth for a vertical filter press and a preparation method thereof.

In order to achieve the purpose, the invention adopts the technical scheme that:

a filter cloth for a vertical filter press is characterized in that the filter cloth is formed by interweaving warps and wefts into a high-strength low-elongation base cloth; then, at least one layer of short fiber net is implanted into the surface layer of the base cloth in a needling mode to form a short fiber gap filtering layer; and then, the low-melting-point fibers on the surface layer are melted and extruded through hot pressing to form the composite filter cloth of the small-aperture filter membrane layer.

The short fiber filtering layer is a fiber layer net formed by needling short fibers on the surface of the base fabric from two sides of the base fabric; wherein, the uppermost fiber layer net of the short fiber filter layer is formed by needling fibers with low melting point.

The short fiber filtering layer is a fiber layer net with more than two layers; wherein the fiber layer net adjacent to the surface of the base cloth is formed by needling of medium-long fibers with high melting points; then, a high-melting-point fiber net can be needled to be used as a filtering interlayer; finally needling the low-melting-point cotton fiber net as a surface film.

The high melting point is more than 200 ℃; the low melting point is 110-150 ℃.

The uppermost fiber layer net contains low-melting-point fibers accounting for 20-100 wt% and high-melting-point fibers accounting for 0-80 wt%.

The preparation method of the filter cloth for the vertical filter press comprises the steps of interweaving warp yarns and weft yarns to form woven high-density base cloth; at least one layer of fiber net is needled on the surface of the base cloth by taking short fibers as raw materials to serve as a short fiber filtering layer, and then a filtering membrane is formed on the surface layer of the short fiber gap filtering layer through hot pressing, namely the composite filtering cloth of the small-aperture filtering membrane layer is formed.

The woven high-strength low-elongation base cloth is formed by interweaving warps and wefts; wherein the yarn is folded by 300-3000D, the warp density is 200-350 pieces/10 cm, and the weft density is 80-200 pieces/10 cm;

the short fiber filtering layer is a fiber layer net formed by needling short fibers on the surface of the base fabric from two sides of the base fabric; wherein, the uppermost fiber layer net of the short fiber filter layer is formed by needling fibers containing low melting point to form a fiber layer net; the short fiber filtering layer is a fiber layer net with more than two layers; wherein the fiber layer net adjacent to the surface of the base cloth is formed by needling of thicker medium long fibers with high melting point, and at least one layer; at least one fiber layer net formed by cotton type fibers with high melting point and thin thickness is arranged between the fiber layer net formed by needling the medium long fibers with high melting point and thick and the fiber layer net formed by needling the fibers containing low melting point.

The high-melting-point medium-long fibers of the filter cloth and the stout medium-long fibers improve the strength and fastness of the short fiber layer; the surface layer of the filter cloth is low-melting-point fiber, and a fine and smooth membrane filter layer is easily formed by the fine cotton fiber after hot pressing.

When the content of the low-melting-point fibers in the upper fiber layer net is 35-100 wt%, filter membranes with different thicknesses are formed;

when the content of the low-melting-point fibers in the upper fiber layer net is 20-35 wt%, the low-melting-point fibers have an adhesion effect, so that the surface fiber has high fastness, and the damage of mechanical external force to the surface fiber is prevented

The hot pressing temperature is 110-150 ℃ and the pressure is 7-8 Pa; the surface of the short fiber filtering layer is formed into a filtering layer with uniform micro-pore diameter by hot pressing.

Use of a filter cloth for a vertical filter press for the filtration of fine material having a particle size of 25 to 1 μm in a vertical filter press.

The invention has the advantages that:

the high-performance vertical type machine-pressing filter cloth is woven into low-stretch cloth as base cloth, then at least one layer of net is needled with short fibers, and then the multi-layer penetration type filter cloth is obtained through hot-pressing film forming or adhesion. Structurally, the multilayer filtering structure is formed by regular yarn interweaving points, randomly distributed fiber gaps and fine membranous micropores. In physical properties, the high-strength base fabric enables the product to realize low-elongation mechanical properties; a smooth surface layer. The method specifically comprises the following steps:

1. the woven high-strength low-elongation base cloth is a stable two-dimensional structure formed by warp yarns and weft yarns, so that the woven high-strength low-elongation base cloth is high in strength, small in elongation and high in dimensional stability, meets the requirement of a filter press on low elongation of filter cloth, and ensures long service life and stable filtering effect.

2. The short fiber filter layer is made of short fibers which are carded primarily to form a net fiber layer, and then fibers are flocked on two sides of the base fabric in a needling mode to form at least one fiber layer net; the fiber layers distributed longitudinally and transversely in the short fiber filtering layer form loose and porous deep filtering and multi-layer filtering, so that the damage of tiny particles to the filtering cloth is reduced, the filtering effect is improved, and the service life of the filtering cloth is prolonged. The fiber layer net on the surface of the base fabric is formed by needling thick medium long fibers with high melting point, and the strong medium long fibers improve the strength and fastness of the short fiber layer. Laying a low-melting-point cotton-type fiber web on the first layer of fiber web, and needling. The finer cotton fibers improve the fineness and smoothness of the surface layer after film formation. On the other hand, the elastic fiber net supports the film fiber layer to form buffering and reduce the damage of the film surface layer.

3. When the weight percentage of the upper layer low-melting-point fiber in the fiber layer net in the short fiber gap filtering layer is 35-100%, filter membranes with different thicknesses are formed; when the weight percentage of the low-melting-point fiber of the upper layer is 20-35%, the low-melting-point fiber plays a role in bonding and reinforcing, so that the surface fiber has high fastness, and the damage of mechanical external force to the surface fiber is prevented.

4. The hot-pressing filter membrane small-aperture filter layer is obtained by a heat treatment method of shaping and calendaring. Because the low-melting-point fiber is melted firstly and a film with consistent thickness, compact structure and uniform pores is formed on the surface layer after pressure is applied, the fine filtration of the surface layer is realized.

The short fiber layer on the surface layer with smooth membrane quality is not polluted by external pressure and filter materials, so that the long-lasting cleanness and elasticity are kept, and the fiber layer is ensured to realize a multi-layer filtering effect. The smooth surface layer enables the filter cake to easily fall off, reduces the abrasion of the filter material to the surface of the fabric, enables the filter cloth to be easily cleaned, and prolongs the service life of the fabric.