Yeu Ming Tai Chemical Industrial Co., Ltd.

Yeu Ming Tai Chemical Ind. Co., Ltd.

William Chou

James Huang

David Chou

Juin-Yih Lai

Kueir-Rarn Lee

Da-Ming Wang

Ruoh-Chyu Ruaan

Tian-Tsair Wu

Woh-Jer Lee

Shia-Chung Chen

Ching-Yao Huang

Lei-Ti Huang

Jenn-Yuh Kau

Yui-Whei Cheng-Yang

The present invention provides an asymmetric porous PTFE membrane for a filter having little change over time and conventionally known properties of a porous PTFE molded article such as water permeability resistance, air permeability, sealing properties and electric properties, in which collection efficiency, air permeability and pressure loss are improved. Specifically, the present invention relates to an asymmetric porous PTFE membrane for a filter comprising a dense skin layer and a continuously foamed porous layer, wherein

Asymmetric porous polytetrafluoroethylene membrane for a filter

The present invention provides an asymmetric porous PTFE membrane for clothing having little change over time and conventionally known properties of a porous PTFE molded article such as water permeability resistance, air permeability, sealing properties and electric properties, in which durability and water vapor permeability are improved by strengthening adhesion strength with fabric. Specifically, the present invention relates to an asymmetric porous PTFE membrane for clothing comprising a dense skin layer and a continuously foamed porous layer, wherein (1) the contact angle of water to the surface of the skin layer is 120 to 140&#xb0;; and (2) the diffuse reflectance of light of the skin layer is 91 to 94%.

Asymmetric porous polytetrafluoroethylene membrane for clothing

The present invention relates to an asymmetric porous polytetrafluoroethylene membrane comprising a dense skin layer and a continuously foamed porous layer, (1) the dense skin layer having a surface roughness Ra of 20 to 165 nm; (2) the dense skin layer having a contact angle for water of 120 to 135&#xb0;; (3) the porous layer having a maximum pore diameter of 0.03 to 1.0 &#x3bc;m; and (4) the membrane having a total porosity of 20 to 70%. The asymmetric porous PTFE membrane has an ability to separate each liquid component from a liquid-liquid homogeneous mixture in addition to known properties such as water permeability resistance, gas permeability, sealing property and electric property, wherein change of these properties over time is small.

Asymmetric porous polytetrafluoroethylene membrane and process for preparing the same

To provide a method of producing a uniaxially stretched polytetrafluoroethylene gasket tape, which comprises: (1) a step for preparing a paste comprising a mixture of a polytetrafluoroethylene powder obtained by emulsion polymerization and an extrusion aid, (2) a step for extruding the paste by means of an extruder equipped with a die which has plural separators inside an orifice thereof having a rectangular cross section, (3) a step for rolling, in the extruding direction, an extrudate having slit lines to give a rolled polytetrafluoroethylene sheet, (4) a step for uniaxially stretching the rolled sheet in the rolling direction after removing the extrusion aid from the rolled sheet, and (5) a step for heat-treating the obtained uniaxially stretched polytetrafluoroethylene sheet. The die of the extruder has plural sheet-like separators in the orifice thereof having a rectangular cross section. The separators are mounted so that free ends thereof are located at a point exceeding a center point of a long side of the orifice, and function to provide slit lines inside the extrudate in parallel with the long side of the orifice. The high performance inexpensive PTFE gasket tape is produced by the uniaxially stretching method and has properties equal to those of biaxially stretched PTFE gasket tape.

Production method of a polytetrafluoroethylene sheet or film

To provide a porous polytetrafluoroethylene sheet which has excellent cold flow resistance and is used suitably for gaskets and a highly densified polytetrafluoroethylene sheet which has high tensile strength and flex life and is used suitably for diaphragms. The porous polytetrafluoroethylene sheet is produced from a polytetrafluoroethylene material having a microstructure of nodes interconnected by fibrils and has MTS of from 3,000 to 12,000 psi and C.I. of 0.02 to 0.20 g/cc/psi. The highly densified polytetrafluoroethylene sheet is produced by compression-molding the porous polytetrafluoroethylene sheet and then sintering completely. The porous polytetrafluoroethylene sheet is also laminated with a sheet of other material to provide a composite polytetrafluoroethylene molded article.

Porous polytetrafluoroethylene molded article

A process for preparing an improved expanded porous polytetrafluorethylene product having a higher density and improved cold flow properties and prepared from a paste formed from a polytetrafluoroethylene resin and a lubricant. The method includes extruding the paste through an extrusion die at a reduction ratio of less than 100, calendering the extrudate, removing the lubricant, and heating the extrudate to a temperature greater than the crystalline melting point of polytetrafluoroethylene but generally below the temperature at which thermal decomposition becomes appreciable while concurrently expanding the extrudate to at least twice its original length.

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Taichung, Taiwan

William Chou