A microporous membrane for filtering and a method for preparing the same, a flat filtering element and a gas filtering article are disclosed. The microporous membrane is composed of following raw materials in parts by weight: 100-110 parts of polyethylene, 27-30 parts of acrylonitrile, 0.1-0.2 parts of dicumyl peroxide, 2-4 parts of plasticizer, 1-2 parts of antimonous oxide, 0.8-1 part of zinc borate, 1-2 parts of antioxidant, 0.8-2 parts of heat stabilizer, 1-2 parts of octylisothiazolinone, 1-3 parts of calcium propionate, 0.7-2 parts of triglycidyl isocyanurate, 4-6 parts of diacetone alcohol, 0.7-1 part of oleic diethanolamide, 0.5-1 part of sodium myrastate and 1-2 parts of glycolic acid.

An air filter medium includes a first porous PTFE membrane and a second porous PTFE membrane. The air filter medium has a first main surface and a second main surface, and the first porous PTFE membrane and the second porous PTFE membrane are arranged so that an air flow moving from the first main surface to the second main surface passes through the first porous PTFE membrane and subsequently through the second porous PTFE membrane. A contact angle of the first porous PTFE membrane with water is in the range of 154° to 165°.

A filter pleat pack of the present disclosure includes an air filter medium folded into pleats. The air filter medium includes a laminate of a polytetrafluoroethylene (PTFE) porous membrane and an air-permeable supporting member. When a cut surface of the filter pleat pack is observed, the cut surface being taken along a plane perpendicularly crossing a pleat line of the filter pleat pack, the PTFE porous membrane has a first converging portion, a split portion, and a second converging portion in this order in a direction in which the membrane extends. In the split portion, the PTFE porous membrane is split into a plurality of layers in a thickness direction of the membrane and the plurality of layers are spaced apart from each other. At the first converging portion and the second converging portion, the plurality of layers converge into one layer. The filter pleat pack of the present disclosure is a filter pleat pack for which a collection efficiency decrease resulting from pleating is reduced.

A filter pleat pack of the present disclosure includes an air filter medium folded into pleats, wherein the air filter medium includes a laminate of a polytetrafluoroethylene (PTFE) porous membrane and an air-permeable supporting member, and the air filter medium has a shrinkage rate of 50% or more, the shrinkage rate being determined by a formula (d2−d1)/d2, where d1 is a smallest thickness of the PTFE porous membrane in a folding area of the air filter medium folded into pleats and d2 is a thickness of the PTFE porous membrane in a flat area of the air filter medium. The filter pleat pack of the present disclosure is a filter pleat pack for which a collection efficiency decrease resulting from pleating is reduced.

A vent assembly (100) has a vent body (110) defining a first end (104) and a second end (106), a central axis extending from the first end to the second end, and an inner surface defining a cavity. A first retainer extends across the cavity towards the first end of the vent body, and a second retainer (140) extends across the cavity towards the second end of the vent body. The first retainer defines a first retainer opening extending to a first radial distance from the central axis, and the second retainer defines a second retainer opening extending to a second radial distance from the central axis, where the second radial distance is greater than the first radial distance. Coalescing filter media is disposed in the cavity between the first retainer and the second retainer. The coalescing filter media, the cavity, the first retainer, and the second retainer cumulatively define an airflow pathway.

The present invention relates to a sheet material and filter element, where the sheet material and the filter element have a hydrophobic separating layer, and also to use thereof and to a process for production of same.

A mask according to an embodiment of the present disclosure may adjust permeability thereof by including and using an air filter unit which is capable of expanding or contracting, in at least one direction, a filter for filtering particles contained in air passing through the mask by pores.

Filter media comprising a pre-filter layer and related components, systems, and methods associated therewith are provided. In some embodiments, the pre-filter layer may be designed to impart desirable properties to the filter media, such as a high gamma and/or long service life, while having relatively minimal or no adverse effects on another property of the filter media that is important for a given application. For instance, a pre-filter layer may be used to improve the upstream removal of fine particulate matter, which may clog a downstream efficiency layer comprising submicron fibers and reduce filtration performance. The pre-filter layer may be configured to increase service life and/or increase the gamma of the filter media. Filter media, as described herein, may be particularly well-suited for applications that involve filtering air, though the media may also be used in other applications.

Embodiments relate generally to a filter (110), for example, for attachment onto a gas detector device or a gas sensor, and attempt to improve the efficiency and service life of the filter (110). Embodiments typically comprise a dustproof membrane (114) and a waterproof membrane (113). Some embodiments may also comprise a splash-proof cap (130) and/or features to reduce negative pressure on the filter (110).

A filter pleat pack includes an air filter medium including: a first porous fluorine resin membrane; and a first air-permeable supporting layer. The first air-permeable supporting layer is placed on a downstream side in a direction of an air flow that passes through the filter medium with respect to the first porous fluorine resin membrane, and includes a ventilation inhibiting portion in at least one end portion in a width direction, the ventilation inhibiting portion extending along the at least one end portion, the ventilation inhibiting portion inhibiting ventilation in the width direction through the first air-permeable supporting layer. The ventilation inhibiting portion is in contact with the first porous fluorine resin membrane. This filter pleat pack is suitable for reducing a decrease in the collection efficiency of an air filter unit even when a gap between a lateral surface of the pleat pack and a frame is sealed.