Domestic Wet Coated Soft Fabrics Will Be Available In April Of This Year.

< p > due to the diffusion of DMF and the stress generated by dewatering and shrinkage in the process of solid film formation, various pores are formed, which is the biggest advantage of wet film forming technology.

At present, a nonwovens manufacturer in Guangzhou has introduced this technology. After the Spring Festival, mass production will begin. Wet film coating products will be on sale in April. This will create the first step in China's "a href=" http://www.91se91.com/news/index_c.asp "wet coating soft fabric" /a.

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< p > different finishing finishing agents, the effect of forming films on nonwovens is also very different.

Besides, the quality of the coating product is related to the quality and the quality of the coating agent.

At present, most domestic finishing enterprises adopt coating solvent evaporation physical film forming technology and hot melt forming technology.

Although the film formed by the coating agent is not completely integrated with the substrate, the coating agent can partially deepen the concave convex part of the nonwoven fabric surface.

Although the durability of the product after coating can be given, it will lead to an increase in the thickness of the product after coating, and at the same time make the product feel stiff.

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< p > however, the mature finishing coating methods in the international market are not limited to these two technologies, such as poly a href= "http://www.91se91.com/news/index_c.asp" > ammoniate coating agent < /a > in addition to the physical film forming of volatile solvents, wet film forming can also be adopted.

When the polyurethane coating wet film enters the coagulation bath composed of 25%~30% two methyl formamide (DMF) aqueous solution, the water seep into the coating film and dissolve with the DMF in the coating film, thereby diluting the DMF on the upper and lower two layers of the coating film, that is, the extraction of DMF, so that the concentration of DMF in the coating decreases, especially the concentration of the bright film DMF of the film decreases significantly.

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< p > at this time, the DMF of the inner layer diffuses outwards due to the attraction of water. The water in the coagulation bath diffuses inward due to the attraction of < a href= "http://www.91se91.com/news/index_c.asp" > DMF < /a >, thus forming bidirectional diffusion.

In the process of continuous diffusion, the coating layer gradually changed from the clarified solution to the turbid gel state of polyurethane -DMF- water.

Bidirectional diffusion continues, producing phase separation in the gel. Solid polyurethane precipitates the bottom and slowly completes the solidification process.

The process has not undergone chemical modification nor will it affect the soft feel of the product.

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< p > in addition, when the coating enters the coagulation bath, DMF diffuses rapidly on the surface of the coating, and a solid membrane with small pores is formed on the surface of the liquid film.

When the polyurethane content is high, the thickness of the surface microporous membrane is large, which makes the internal DMF diffused slowly, and the sponge structure is easily formed inside the membrane.

When the concentration of DMF in the coagulation bath is low, the DMF on the surface rapidly diffuses into the coagulation bath, and a dense solid membrane is formed quickly on the surface of the liquid membrane.

The thinner solid film produces the tendency of dehydration contraction and the stress in the contraction during the forming process.

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< p > because of the gelation state, it is impossible to pfer through the flow of polymer and can only be eliminated by the peristalsis of polymer macromolecules.

When the shrinkage stress is too fast and the peristalsis of polymer colloids is too late to eliminate stress, cracks are generated at the stress concentration of the polymer film.

This crack forms the initial state of the finger structure hole. Once the crack is formed, the crack will gradually expand with the contraction of the solid membrane.

With the inward diffusion of the endometrium, the finger structure is formed until the bottom of the coating is formed.

Between fingers and fingers, the solid membrane contracts slowly, forming sponge like pores due to the obstruction of the surface layer.

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< p > at present, a nonwovens manufacturer in Guangzhou has introduced this technology. After the Spring Festival, mass production will begin, and wet film coating products will be on sale in April. This will create a precedent for domestic wet coated soft fabrics.

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