Two Hydrophilic Finishing Methods To Improve The Surface Wettability Of Nonwovens

< p > > a href= "http:// www.91se91.com/news/index_c.asp" > hydrophilic finishing > /a > the purpose is to make hydrophobicity of the fiber surface produce hydrophilic effect. Only when the contact angle is less than 90 degrees, the liquid (mainly water here) can moisten the solid surface and enter and completely spread on the solid surface.

The so-called wetting is the phenomenon that the gas adsorbed on the solid surface is replaced by liquid.

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< p > wettability and water absorption of fiber surface are mainly determined by the chemical structure and crystalline state of macromolecules, i.e. whether there are quantities of hydrophilic groups and hydrophilic groups on macromolecules.

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< p > the absorbency of the fibers depends mainly on the micropores in the fibers, < a href= "http://? www.91se91.com/news/index_c.asp" > gap < /a > and < a href= "http:// www.91se91.com/news/index_c.asp" > fiber > /a > capillary pores.

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< p > in fact, there are many ways to improve the surface wettability of nonwovens. In general, they can be divided into two categories. One is to get moisture absorption and wettability through fiber modification at spinning stage; the second is to modify the surface of fibers by finishing method, so as to obtain moisture absorption and wettability.

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< p > super absorbent polymer has various kinds and different products.

There are many classification methods, which are generally classified in four ways according to the raw materials, hydrophilic methods, cross-linking methods and product forms.

According to the sources of raw materials, they can be divided into three categories: modified starch, modified starch, including starch graft acrylonitrile hydrolysate, starch graft acrylic acid, starch grafted acrylamide, starch carboxymethyl compound and so on. Modified cellulose mainly includes cellulose grafted acrylonitrile hydrolysate, cellulose grafted acrylic acid, cellulose grafted acrylamide and cellulose carboxymethyl compound; synthetic polymers include crosslinked polyacrylate, crosslinked polyacrylamide, acrylic ester and vinyl acetate copolymer hydrolysate, polyvinyl alcohol and anhydride crosslinking copolymer.

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< p > if classified according to hydrophilic method, it can be divided into polymerization of hydrophilic monomers, copolymerization of hydrophobic monomers and hydrophilic monomers, hydrolysis of cyano and lipophilic groups. Crosslinking methods can be divided into crosslinker crosslinking, bulk crosslinking, radiation crosslinking, and introducing hydrophobic groups or crystal structures into hydrophilic polymers. According to the product form, they can be divided into powder, fibrous, flake, film and foam.

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< p > because the super absorbent polymer is a cross-linked material, it can not be processed by heating and solvent dissolving.

At present, most non-woven enterprises at home and abroad adopt the way of processing the super absorbent polymer into powder, then evenly distribute on the surface of the base material, then cover it with a layer of base material, so that the super absorbent polymer is sandwiched between two layers of base material, such as diapers, sanitary napkins, medical mats and so on.

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< p > but there are only two types of absorbent: anionic and nonionic. The water absorbency of the anion absorbent is high, but the salt tolerance is poor. Nonionic super absorbent has the characteristics of fast water absorption, good salt tolerance, but low water absorbency.

Therefore, the production of super absorbent polymers through these two ways is actually not "high performance".

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