Abstract: An air filter medium includes a fluororesin porous membrane and a supporting member stacked on top of each other. The air filter medium has a permeability ratio (permeability after disinfection treatment/permeability before disinfection treatment) of 5.0 or less, the permeability ratio being a ratio of permeabilities of the air filter media before and after the disinfection treatment of the fluororesin porous membrane as determined using NaCl particles having a particle size of 0.1 ?m, and a pressure loss ratio (pressure loss after disinfection treatment/pressure loss before disinfection treatment) of 0.83 or more and 1.15 or less, the pressure loss ratio being a ratio of pressure losses of the air filter media before and after the disinfection treatment of the fluororesin porous membrane.

Abstract: An air filter medium includes a fluororesin porous membrane and an air-permeable supporting member stacked on the fluororesin porous membrane. The fluororesin porous membrane has a pressure loss of 80 Pa or less when air is passed at a flow rate of 5.3 cm/s. The fluororesin porous membrane has a PF of 20 or more, the PF being determined from a formula PF={?log((100?collection efficiency (%))/100)}/(pressure loss (Pa)/1000) using the pressure loss and a collection efficiency determined using NaCl particles having a particle size of 0.1 ?m. The fluororesin porous membrane has a thickness of 10 ?m or more. A dust-holding capacity of polyalphaolefin particles having a number median diameter of 0.25 ?m is 15.0 g/m2 or more when air containing the polyalphaolefin particles is continuously passed through the fluororesin porous membrane at a flow rate of 5.3 cm/s and pressure loss increases by 250 Pa.

Abstract: An air filter medium reduces a decrease in collection efficiency in the case where a main collection layer and a pre-collection layer having a lower collection efficiency than the main collection layer are used. An air filter medium that collects dust in gas includes a main collection layer and a pre-collection layer that has a lower collection efficiency of NaCl particles having a particle size of 0.3 ?m than the main collection layer, is disposed on an upstream side of an air flow with respect to the main collection layer, and has water repellency.

Abstract: An air filter medium having a large thickness and a low filling factor, a filter pack, an air filter unit, and methods for producing the air filter medium, the filter pack, and the air filter unit are provided. The air filter medium includes a fluororesin porous film having a portion with a filling factor of 3.5% or less, and the portion with a filling factor of 3.5% or less has a thickness of 45 ?m or more.

Abstract: A tetrafluoroethylene polymer is provided in an air filter medium having a pressure loss that can be reduced and made uniform at a plurality of positions. The tetrafluoroethylene polymer may also be provided in an air filter medium, a filter pack, or an air filter unit. The tetrafluoroethylene polymer has drawability and non-melt processability. The tetrafluoroethylene polymer has a ratio S2/S1 of 0.60 or more, where S2 represents an endotherm mJ/mg in a range of T0° C. or higher and 350° C. or lower, T0° C. is a temperature 2.5° C. lower than a temperature Tp° C. (340?Tp?345) at which a minimum point is given on a heat-of-fusion curve obtained by measuring an unbaked polymer for measurement having no history of heating to a temperature of 300° C. or higher using a differential scanning calorimeter at a temperature-increasing rate of 2° C./min, and S1 represents an endotherm mJ/mg in a range of 320° C. or higher and T0° C. or lower.

Abstract: There are provided an air filter medium, a filter pack, and an air filter unit in which the decrease in collection efficiency can be suppressed. The air filter medium includes a fluororesin. The PAO permeability ratio (final permeability/initial permeability) is less than 3.0. The initial permeability is a permeability of polyalphaolefin particles when air containing the polyalphaolefin particles having a number median diameter of 0.25 ?m is passed through the air filter medium at a flow velocity of 5.3 cm/s. The final permeability is a permeability of polyalphaolefin particles when air containing the polyalphaolefin particles having a number median diameter of 0.25 ?m is continuously passed through the air filter medium at a flow velocity of 5.3 cm/s and the pressure loss is increased by 250 Pa.

Abstract: The present invention provides a porous body having high strength, a small pore size, and excellent homogeneity. The porous body of the present invention includes polytetrafluoroethylene and has a microstructure that includes nodes and fibrils. The microstructure further includes, in addition to the nodes and the fibrils, fused points where a fibril that links two nodes and another fibril that links another two nodes are fused with each other.

Abstract: An air filter medium reduces a decrease in collection efficiency in the case where a main collection layer and a pre-collection layer having a lower collection efficiency than the main collection layer are used. An air filter medium that collects dust in gas includes a main collection layer and a pre-collection layer that has a lower collection efficiency of NaCl particles having a particle size of 0.3 ?m than the main collection layer, is disposed on an upstream side of an air flow with respect to the main collection layer, and has water repellency.

Abstract: A filter medium for an air filter includes a pre-collection member, a first porous film, and a second porous film arranged in order from the side that is upstream of the air current. Each of the first porous film and the second porous film has a pressure loss of 30 Pa or more and 90 Pa or less when air is passed through each porous film at a flow rate of 5.3 cm/s, and has a collection efficiency of 95% or more and 99.9% or less for NaCl particles having a particle diameter of 0.3 ?m when air containing the NaCl particles is passed through each of the porous films at a flow rate of 5.3 cm/s. The pre-collection member has a pressure loss of 5 Pa or more and less than 55 Pa when air is passed through the pre-collection member at a flow rate of 5.3 cm/s, has a collection efficiency of 15% or more and less than 85% for NaCl particles having a particle diameter of 0.3 ?m when air containing the NaCl particles is passed through the pre-collection member at a flow rate of 5.3 cm/s, and has a thickness of more than 0.

Abstract: A filter medium for an air filter includes a pre-collection member, a first porous film, and a second porous film arranged in order from the side that is upstream of the air current. Each of the first porous film and the second porous film has a pressure loss of 30 Pa or more and 90 Pa or less when air is passed through each porous film at a flow rate of 5.3 cm/s, and has a collection efficiency of 95% or more and 99.9% or less for NaCl particles having a particle diameter of 0.3 ?m when air containing the NaCl particles is passed through each of the porous films at a flow rate of 5.3 cm/s. The pre-collection member has a pressure loss of 5 Pa or more and less than 55 Pa when air is passed through the pre-collection member at a flow rate of 5.3 cm/s, has a collection efficiency of 15% or more and less than 85% for NaCl particles having a particle diameter of 0.3 ?m when air containing the NaCl particles is passed through the pre-collection member at a flow rate of 5.3 cm/s, and has a thickness of more than 0.

Abstract: A filter medium includes first and second porous films mainly containing fluororesin, and a pre-collection member upstream of the first film. The pre-collection member has a pressure drop when air is passed through at a flow rate of 5.3 cm/s of between 15 Pa and 55 Pa, a collection efficiency of NaCl particles having a particle diameter of 0.3 ?m when air containing the particles is passed through at a flow rate of 5.3 cm/s of between 25% and 80%, a thickness of 0.4 mm or less, and a PF value between 7 and 15. A ratio of the PF value of the pre-collection member to the PF value when the first and second films are overlapped, is between 0.20 and 0.45. The filter medium can be in a filter pack or filter unit, and produced by integrating the films and the pre-collection member using heat lamination.

Abstract: A filter medium includes first and second porous films mainly containing fluororesin, and a pre-collection member upstream of the first film. The pre-collection member has a pressure drop when air is passed through at a flow rate of 5.3 cm/s of between 15 Pa and 55 Pa, a collection efficiency of NaCl particles having a particle diameter of 0.3 ?m when air containing the particles is passed through at a flow rate of 5.3 cm/s of between 25% and 80%, a thickness of 0.4 mm or less, and a PF value between 7 and 15. A ratio of the PF value of the pre-collection member to the PF value when the first and second films are overlapped, is between 0.20 and 0.45. The filter medium can be in a filter pack or filter unit, and produced by integrating the films and the pre-collection member using heat lamination.

Abstract: A filtering medium includes first and second porous membranes mainly composed of fluororesin, and a plurality of air permeable supports to support the first and second membranes. The second membrane is disposed downstream of the first membrane. When air containing polyalphaolefin particles with a count median diameter of 0.25 ?m is continuously passed through at a flow rate of 5.3 cm/sec and pressure loss is increased by 250 Pa, the first membrane has a dust retention amount larger than the second membrane. The filtering medium has a pressure loss of less than 200 Pa when air is passed through at a flow rate of 5.3 cm/sec. A collecting efficiency of NaCl particles with a particle diameter of 0.3 ?m is 99.97% or more when air containing the NaCl particles is passed through at a flow rate of 5.3 cm/sec. The dust retention amount is 25 g/m2 or more.

Abstract: A mixed powder and a material for molding have polytetrafluoroethylene as a main component. Each includes polytetrafluoroethylene that can be fibrillated, a non-hot melt processable component that is not fibrillated, and a hot melt processable component with a melting point of lower than 320° C. that is not fibrillated. The non-hot melt processable component that is not fibrillated is contained in a range of 20 to 40% by weight of the total weight. The hot melt processable component is contained at equal to or more than 0.1% by weight but less than 20% by weight of the total weight. A drawn porous body includes a plurality of fibrils, and a plurality of knotted portions that are connected to each other by the fibrils.

Abstract: An embossed air filter filtration medium has at least one porous film and a plurality of air-permeable support materials supporting the at least one porous film. The least one porous film includes a fibril-formable polytetrafluoroethylene, a non-fibril-forming and non-hot-melt-processable component, and a non-fibril-forming and hot-melt-processable component having a melting point below 320° C. Surfaces of both sides of the air filter filtration medium are formed by two air-permeable support materials of the air-permeable support materials. The air filter filtration medium has a plurality of embossed projections. The embossed air filter filtration medium may be part of a filter pack, which may be part of an air filter unit. The embossed air filter filtration medium is manufactured by laminating air-permeable support materials on the at least one porous film and embossing the air filter filtration medium to form the projections.

Abstract: A filter medium includes first and second porous films mainly containing fluororesin, and a pre-collection member upstream of the first film. The second film is downstream of the first film. The pre-collection member has a pressure drop when air is passed through at a flow rate of 5.3 cm/s of between 15 Pa and 55 Pa, a collection efficiency of NaCl particles having a particle diameter of 0.3 ?m when air containing the particles is passed hrough at a flow rate of 5.3 cm/s of between 25% and 80%, a thickness of 0.4 mm or less, and a PF value between 7 and 15. The PF value={?log((100?collection efficiency (%))/100)}/(pressure drop (Pa)/1000). A ratio of the PF value of the pre-collection member to the PF value when the first and second films are overlapped, is between 0.20 and 0.45. The filter medium can be used in a filter pack or filter unit, and may be produced by integrating the first and second films and the pre-collection member using heat lamination.

Abstract: A mixed powder and a material for molding have polytetrafluoroethylene as a main component. Each includes polytetrafluoroethylene that can be fibrillated, a non-hot melt processable component that is not fibrillated, and a hot melt processable component with a melting point of lower than 320° C. that is not fibrillated. The non-hot melt processable component that is not fibrillated is contained in a range of 20 to 40% by weight of the total weight. The hot melt processable component is contained at equal to or more than 0.1% by weight but less than 20% by weight of the total weight. A drawn porous body includes a plurality of fibrils, and a plurality of knotted portions that are connected to each other by the fibrils.

Abstract: A filter medium includes first and second porous films mainly containing fluororesin, and a pre-collection member upstream of the first film. The second film is downstream of the first film. The pre-collection member has a pressure drop when air is passed through at a flow rate of 5.3 cm/s of between 15 Pa and 55 Pa, a collection efficiency of NaCl particles having a particle diameter of 0.3 ?m when air containing the particles is passed hrough at a flow rate of 5.3 cm/s of between 25% and 80%, a thickness of 0.4 mm or less, and a PF value between 7 and 15. The PF value={?log((100?collection efficiency (%))/100)}/(pressure drop (Pa)/1000). A ratio of the PF value of the pre-collection member to the PF value when the first and second films are overlapped, is between 0.20 and 0.45. The filter medium can be used in a filter pack or filter unit, and may be produced by integrating the first and second films and the pre-collection member using heat lamination.

Abstract: A composition, a mixed powder and a material for molding have polytetrafluoroethylene as a main component. Each includes polytetrafluoroethylene that can be fibrillated, a non-hot melt processable component that is not fibrillated, and a hot melt processable component with a melting point of lower than 320° C. that is not fibrillated. The hot melt processable component is contained at equal to or more than 0.1% by weight but less than 20% by weight of a total weight. A filtering medium for an air filter includes a porous membrane made of these components, and an air permeable support. The porous membrane is manufactured, by mixing these components, extruding the mixture, rolling and drawing.

Abstract: A filtering medium includes first and second porous membranes mainly composed of fluororesin, and a plurality of air permeable supports to support the first and second membranes. The second membrane is disposed downstream of the first membrane. When air containing polyalphaolefin particles with a count median diameter of 0.25 ?m is continuously passed through at a flow rate of 5.3 cm/sec and pressure loss is increased by 250 Pa, the first membrane has a dust retention amount larger than the second membrane. The filtering medium has a pressure loss of less than 200 Pa when air is passed through at a flow rate of 5.3 cm/sec. A collecting efficiency of NaCl particles with a particle diameter of 0.3 ?m is 99.97% or more when air containing the NaCl particles is passed through at a flow rate of 5.3 cm/sec. The dust retention amount is 25 g/m2 or more.