Pre-coating film

Abstract

The invention discloses a pre-coated membrane which comprises a base membrane, an ultrafiltration layer and a water-permeable supporting layer which are sequentially laminated, the base film is a plastic film; the water-permeable supporting layer is thicker than the ultrafiltration layer; the ultrafiltration layer is composed of a resin coating, and inorganic nanoparticles are uniformly distributed in the resin coating; the permeable supporting layer is composed of a resin coating, and inorganic particles are uniformly distributed in the resin coating; the particle size of inorganic particles in the water-permeable supporting layer is larger than that of inorganic nano-particles in the ultrafiltration layer. The method can be used for manufacturing the nanometer water filtering layer with the thickness smaller than 0.1 micrometer, the thickness deviation range can be controlled within +/-10%, and the ultra-thin degree and the thickness precision of the nanometer water filtering layer are far better than those of a traditional technology. According to the water purification product manufactured by the invention, the blockage of impurities in water can be greatly reduced, and the backflushing cleaning can be carried out in a shorter time and at a lower backflushing water pressure, and less backflushing sewage can be generated.

Description

technical field [0001] The invention relates to a pre-coating film with a multi-layer gradient structure, in particular to a pre-coating film used in making microfiltration and ultrafiltration water purification materials, and belongs to the field of new functional materials. Background technique [0002] At present, ceramic ultrafiltration membranes have been used in liquid filtration, concentration, and solid-liquid separation in water treatment, food processing, biochemical and other industries. Due to the limitations of the powder stacking and sintering process in the prior ceramic membrane production process, the distribution of filter pores is uneven, the range of pore size difference is large, and the difference between the minimum pore size and the maximum pore size is dozens of times. This situation has a serious impact on the performance of ceramic ultrafiltration membranes in practical applications, and the problem is manifested in the contradiction between filtra...

AI Technical Summary

Problems solved by technology

However, from the surface, the surface of the slurry layer through natural leveling or scraping is very smooth, but if there is unevenness on the surface of the substrate, the thickness of the slurry layer will vary, and the concave part of the substrate will be filled with more slurry. The slurry increases the thickness of the slurry layer, while the slurry layer on the protruding part of the substrate becomes thinner. Since the thickness of some ultrafiltration membrane layers is only 0.1 microns, the flatness accuracy of the substrate surface formed by mechanical means is not in the same order of magnitude as the thickness of the membrane layer. Compared with the reference value of 0.1 micron, the thickness error ratio of the final film layer formed by the slurry natural leveling or scraping process will be very large

[0005]The ceramic ultrafiltration membrane in the traditional technology not only has the contradiction between filtration accuracy and flux, but also has an ultra-thick ultrafiltration layer that forms an overly long filter channel, which makes the water The debris is more likely to block the filter channel and cause backwash cleaning to be ineffective. The above problems are caused by the poor thickness and uniformity of the filter membrane layer in the membrane manufacturing process.

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