Research Of Clean Room Fabrics Of High-filtration

Clean room fabrics, also known as anti-static clean room clothing, are currently widely used in medicine, microelectronics, precision instrument, precision machinery, food industry, life engineering and fine chemical industry. Clean room clothing itself should not become a dust emission sources; should have a certain particle filtration to the dust generated by the human skin; should prevent static electricity. In addition, clean room clothing have to meet human comfort requirements in order to adapt to needs of sports, action, physical and psychological. At present, most of enterprises try to minimize the pores of the fabric by increasing the density or laminated PTFE so as to improve the dust filtration. However, the high cost, bad handle and poor moisture permeability limit the application of these kinds of products.Since fabric is the basis of apparel fabrics, this article focused on the coating mechanism and processing so as to reduce the fabric pores. Clean room fabric was produced by using solvent-based polyurethane and water-based polyurethane. The coating process was studied, such as fabric, pre-treatment, coating amount, viscosity, drying conditions and other factors. The moisture permeability and handle was improved by adding PEG and chitosan.It was found that, with the increasing of coating amount, there was a large reduction in moisture permeability although the dust filtration increased. When the coating amount was high enough, the fabric was very stiff and coated surface was difficult to be dried, which made the surface sticky and decreased the integrity of the film. Drying was the key process of coated fabrics, with the increase of drying condition, the wash fastness of the fabric was improved a lot. However, if the temperature was too severe, the mechanical properties reduced and the coating turned to yellow. In the paper, the moisture permeability of fabrics was improved by adding PEG and chitosan. The study found that fabric and pre-treatment had a great impact on the properties of coated fabrics, when the fabric had a high tightness, the dust filtration was much better.Since Polyvinylidene fluoride (PVDF) is an excellent membrane material, PVDF was used to coat the fabric to obtain high dust filtration in order to take the place of the traditional PTFE laminated clean room clothes. This kind of fabric had high dust filtration, excellent moisture permeable, good handle and lower cost. It was found that, with increase of PVDF concentration in coating solution, the porous of surface gradually reduced, moisture permeability and air permeability decreased, while the dust filtration increased.Additives in coating solution had a great effect on the dust filtration and moisture permeability of clean room fabrics. When hydrophilic additives such as polyethylene glycol(PEG) was used, the moisture permeability of coated fabrics is improved. With the increase of PEG molecular weight, dust filtration of coated fabrics turned to lower, while moisture permeability and air permeability were increased. When lithium chloride (LiCl) was used as the additive, with the increase of LiCl concentration , the surface microporous increased, dust filtration decreased and moisture permeability enhanced. When dimethylacetamide (DMAc), dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) were used as solvent, the pore structure of coated membranes' cross-section were studied. It was found that the membrane had a symmetrical finger-shaped hole and a flatter superstratum when DMAc was used as the solvent, and the dust filtration was better too. The composition of coagulation bath was studied too, it turned that the diffuse rate of non-solvent into the membrane liquid was slowed and the precipitation rate of PVDF was reduced by adding ethanol. While the number of micro porous was decreased, which made a slight increase of dust filtration by adding sodium chloride.A series of comfort and function tests were performed including air permeability test, abrasive voltage test, stable voltage and particle filtration. This study provides some reliable data for designing and producing the uniform.