Abstract: Polytetrafluoroethylene porous film is laminated with an ultra high molecular weight polyolefin porous film to realize excellent formability, dust collecting ability, and permeability that could not be attained by these porous films used alone. The laminate, which can be formed to prescribed shape if desired, is used to make a container for holding an adsorbent.

Abstract: The present invention is to provide a filter medium for a turbine in which contamination is less likely to be caused in the turbine, and an increase in pressure loss is suppressed. One form of this filter medium includes a porous polytetrafluoroethylene (PTFE) membrane and an air-permeable supporting member. The air-permeable supporting member has a fiber diameter of not more than 15 &mgr;m. This filter medium is used by disposing the air-permeable supporting member on an upstream side of the porous PTFE membrane with respect to air flow passing through the filter medium toward the turbine. Another form of the filter medium of the present invention includes a porous PTFE membrane, a first air-permeable supporting member, and a second air-permeable supporting member.

Abstract: An antibacterial air filter medium has at least one layer of a porous polytetrafluoroethylene film and at least one layer of an antibacterial reinforcing material which may be colored so as to make dirt inconspicuous; the antibacterial air filter medium retains its filtering performance even in an environment rich in water and can be inhibited from undergoing the growth of bacteria or mold fungi even in such an environment; and the antibacterial air filter medium, even when used after washing with water or in a high-humidity environment, does not undergo a decrease in filtering property such as particle collection efficiency and can be inhibited from undergoing the growth of bacteria or mold fungi thereon.

Abstract: The present invention is to provide a filter medium for a turbine in which contamination is less likely to be caused in the turbine, and an increase in pressure loss is suppressed. One form of this filter medium includes a porous polytetrafluoroethylene (PTFE) membrane and an air-permeable supporting member. The air-permeable supporting member has a fiber diameter of not more than 15 &mgr;m. This filter medium is used by disposing the air-permeable supporting member on an upstream side of the porous PTFE membrane with respect to air flow passing through the filter medium toward the turbine. Another form of the filter medium of the present invention includes a porous PTFE membrane, a first air-permeable supporting member, and a second air-permeable supporting member.

Abstract: Turbine air filter media include at least one porous film of polytetrafluoroethylene, and at least one air-permeable support member, wherein the turbine air filter media exhibit a pressure drop of from 100 Pa to 300 Pa, both inclusively, and a PF value of not smaller than 15. The porous film of polytetrafluoroethylene preferably exhibits a pressure drop of from 70 Pa to 250 Pa, both inclusively, and a PF value of not smaller than 18.

Abstract: An air filter comprising a laminate of a non-woven fabric made up of polyolefin fibers or polyester fibers or a composite of the non-woven fabrics and a PTFE porous film, wherein the amount of the total gases generated from the air filter is 20 &mgr;g/g by the analysis of gas chromatography. The amount of the gases generated from the air filter is greatly reduced by heat-treating the non-woven fabric at a temperature of from 80 to 130° C. for 5 minutes to 20 minutes before or after laminating with the PTFE porous film.

Abstract: A filtering medium for air filters, comprising a laminate including at least one porous polytetrafluoroethylene (PTFE) membrane and at least one air-permeable supporting member, the filtering medium having a surface potential of 0.3 kV or lower in terms of absolute value. By regulating the absolute value of surface potential so as to be within that range, the formation of a through-hole attributable to a discharge (spark) caused by, e.g., contact with a bare hand can be prevented. Thus, the leakage phenomenon observed in filtering media for air filter using a porous PTFE membrane can be inhibited.

Abstract: A filter medium for filters wherein the evolution of organic gases and dusting from a reinforcing member are depressed and thus the excellent characteristics inherent to a porous polytetrafluoroethylene membrane as a collection layer are fully achieved. The filter medium (1) for filters comprises a porous polytetrafluoroethylene membrane (2) and a porous ultrahigh-molecular weight polyolefin membrane (3) as a reinforcing member for the filter medium.

Abstract: A filter medium for air filters wherein the collection performance of polytetrafluoroethylene (PTFE) membranes is not damaged even after processing, for example, pleating and bonding to air-permeable supporting members. The filter medium containing a laminate (2) containing at least three layers of porous PTFE membranes wherein the pressure drop of a porous PTFE membrane (4) located as an outermost layer has a pressure drop of 1/2 times or less the pressure drop of porous PTFE membrane (5) located as at least one intermediate layer. Air-permeable supporting members (3) are bonded to both outermost layers of the laminate (4) to obtain a filter medium for air filters (1).

Abstract: A filtering medium for air filters wherein its surface conditions have been improved, whereby the porous PTFE membrane is not damaged even after pleating, thus appropriately meeting needs for clean space in clean rooms. The filtering medium comprises a porous polytetrafluoroethylene membrane (2) and an air-permeable supporting member (1) which are laminated such that at least one of exposed surfaces comprises a surface of the air-permeable supporting member (1) having a maximum frictional resistance of 25 gf or less. This filtering medium can be obtained by, for example, press bonding the air-permeable supporting member (1) to the porous membrane (2) under heating and then pressing the surface of the air-permeable supporting member (1) to a silicone roll (4) for smoothing.

Abstract: An air filter comprising a laminate of a non-woven fabric made up of polyolefin fibers or polyester fibers or a composite of the non-woven fabrics and a PTFE porous film, wherein the amount of the total gases generated from the air filter is 20 .mu.g/g by the analysis of gas chromatography. The amount of the gases generated from the air filter is greatly reduced by heat-treating the non-woven fabric at a temperature of from 80 to 130.degree. C. for from 5 minutes to 20 minutes before or after laminating with the PTFE porous film.

Abstract: A fine powder of polytetrafluoroethylene is mixed with a liquid lubricant, and the mixture is molded into an unsintered sheet by at least one of an extrusion method and a rolling method. The liquid lubricant is removed from the sheet by at least one of a heating method and an extrusion method. This sheet-form molding is stretched in the machine direction to produce a sheet-form polytetrafluoroethylene molding which, upon analysis with a differential scanning calorimeter, gives a crystal fusion curve having an endothermic peak in the temperature range of 345.+-.5.degree. C. and which has a degree of crystallization of from 0.1 to 0.85 and a specific gravity of 1.4 or lower. The molding is then stretched in the transverse direction to produce a porous polytetrafluoroethylene (PTFE) membrane. The process is effective in producing, with good reproducibility, a useful porous PTFE membrane which has a high collection efficiency and a low pressure loss and is reduced in the leakage of coarse particles.

Abstract: A fine powder of polytetrafluoroethylene is mixed with a liquid lubricant, and the mixture is molded into an unsintered sheet by at least one of an extrusion method and a rolling method. The liquid lubricant is removed from the sheet by at least one of a heating method and an extrusion method. This sheet-form molding is stretched in the machine direction to produce a sheet-form polytetrafluoroethylene molding which, upon analysis with a differential scanning calorimeter, gives a crystal fusion curve having an endothermic peak in the temperature range of 345.+-.5 .degree. C. and which has a degree of crystallization of from 0.1 to 0.85 and a specific gravity of 1.4 or lower. The molding is then stretched in the transverse direction to produce a porous polytetrafluoroethylene (PTFE) membrane. The process is effective in producing, with good reproducibility, a useful porous PTFE membrane which has a high collection efficiency and a low pressure loss and is reduced in the leakage of coarse particles.