Abstract: The present invention provides a depth filter which contains fine particles and coarse particles, and which exhibits excellent filtration precision with respect to a high concentration fluid and/or a high viscosity fluid. This depth filter enables filtration for a long period of time, while maintaining a low filtration pressure. The present invention is a depth filter which is obtained by winding a fiber sheet into a cylinder, and which comprises a pre-filtration layer and a microfiltration layer; the pre-filtration layer and the microfiltration layer are formed of a fiber sheet; the fiber sheet is composed of a nonwoven fabric or a web; the average fiber diameter of the fiber sheet continuously decreases from the pre-filtration layer toward the microfiltration layer; and the average weight per square meter of the fiber sheet continuously decreases from the pre-filtration layer toward the microfiltration layer.

Abstract: This depth filter comprises a substrate layer, a filtration layer, and a skin layer in this order. The substrate layer and the skin layer are layers obtained by winding and thermally fusing a nonwoven cloth configured from fibers having an average fiber diameter of 150 ?m or more. The filtration layer is a layer obtained by winding a layered body two or more times, the layered body containing at least a net and a nonwoven cloth included only in the filtration layer. The average fiber diameter of the nonwoven cloth constituting the substrate layer and the average fiber diameter of the nonwoven cloth constituting the skin layer are larger than the average fiber diameter of the nonwoven cloth included only in the filtration layer.

Abstract: A depth filter with excellent filtration accuracy and pressure resistance performance even for fluids containing high density and high viscosity powder fine particles. A depth filter having a base material layer, a filtration layer, and a skin layer, in that order, wherein: the substrate layer and the skin layer are layers made by a nonwoven fabric being wound and thermally fused; the filtration layer is a laminate in which at least a nonwoven fabric and a net are laminated, being wound twice or more; and the nonwoven fabric contained in the filtration layer contains a mixed-fiber nonwoven fabric containing two or more types of fibers with mutually different average fiber diameters.

Abstract: A hollow cylindrical depth filter formed of fibers of a thermoplastic resin and having a thickness of a filter medium of 5 to 25 millimeters, in which the filter medium has a compression ratio of 0.2 or less when a load of 0.5 MPa is applied thereto, the filter medium has a fiber layer of at least three layers from a fluid inflow side toward an outflow side, porosity of the three layers are adjusted to a specific range, respectively, and intersection points of the fibers forming the filter medium are bonded, a mean interval between the intersection points is 2 to 100 times a mean fiber diameter of the fibers in a length direction, and a ratio of the mean fiber diameter on a surface on an upstream side to the mean fiber diameter on a surface on a downstream side of the filter medium is 0.9 to 1.2.

Abstract: A hollow cylindrical depth filter formed of fibers of a thermoplastic resin and having a thickness of a filter medium of 5 to 25 millimeters, in which the filter medium has a compression ratio of 0.2 or less when a load of 0.5 MPa is applied thereto, the filter medium has a fiber layer of at least three layers from a fluid inflow side toward an outflow side, porosity of the three layers are adjusted to a specific range, respectively, and intersection points of the fibers forming the filter medium are bonded, a mean interval between the intersection points is 2 to 100 times a mean fiber diameter of the fibers in a length direction, and a ratio of the mean fiber diameter on a surface on an upstream side to the mean fiber diameter on a surface on a downstream side of the filter medium is 0.9 to 1.2.

Abstract: Shown is a filter in which powder aggregation (bridge) is hard to occur, and a time until a rise of differential pressure is caused is long, more specifically, a filtration life is long. The filter has a base material layer, a filtration layer and a skin layer, in which the base material layer is a layer formed by a nonwoven fabric being wound in a multiple manner, and subjected to the thermocompression bonding, the filtration layer is a layer formed by a laminate prepared by laminating at least a through-air nonwoven fabric and a net, being wound in a multiple manner, and subjected to no thermocompression bonding, the skin layer is a layer including a nonwoven fabric, and a mean pore diameter of the nonwoven fabric composing the base material layer and the skin layer is larger than a mean pore diameter of the through-air nonwoven fabric composing the filtration layer.

Abstract: A hollow cylindrical depth filter formed of fibers of a thermoplastic resin and having a thickness of a filter medium of 5 to 25 millimeters, in which the filter medium has a compression ratio of 0.2 or less when a load of 0.5 MPa is applied thereto, the filter medium has a fiber layer of at least three layers from a fluid inflow side toward an outflow side, porosity of the three layers are adjusted to a specific range, respectively, and intersection points of the fibers forming the filter medium are bonded, a mean interval between the intersection points is 2 to 100 times a mean fiber diameter of the fibers in a length direction, and a ratio of the mean fiber diameter on a surface on an upstream side to the mean fiber diameter on a surface on a downstream side of the filter medium is 0.9 to 1.2.

Abstract: There is provided a pleated cartridge filter for high-purity chemicals that minimizes elution of metal from polyethylene into high-purity chemicals and is suitable mainly for a resist manufacturing process. A cylindrical pleated cartridge filter including a cylindrical core, a pleated filter material wound on the core, and caps sealing both ends of the core, wherein the pleated filter material is composed of a filtration membrane and a spacer laminated together, and the spacer is a nonwoven fabric made of polyethylene fibers having a metal element content of less than 40 ppm.

Abstract: Shown is a filter in which powder aggregation (bridge) is hard to occur, and a time until a rise of differential pressure is caused is long, more specifically, a filtration life is long. The filter has a base material layer, a filtration layer and a skin layer, in which the base material layer is a layer formed by a nonwoven fabric being wound in a multiple manner, and subjected to the thermocompression bonding, the filtration layer is a layer formed by a laminate prepared by laminating at least a through-air nonwoven fabric and a net, being wound in a multiple manner, and subjected to no thermocompression bonding, the skin layer is a layer including a nonwoven fabric, and a mean pore diameter of the nonwoven fabric composing the base material layer and the skin layer is larger than a mean pore diameter of the through-air nonwoven fabric composing the filtration layer.

Abstract: There is provided a pleated cartridge filter for high-purity chemicals that minimizes elution of metal from polyethylene into high-purity chemicals and is suitable mainly for a resist manufacturing process. A cylindrical pleated cartridge filter including a cylindrical core, a pleated filter material wound on the core, and caps sealing both ends of the core, wherein the pleated filter material is composed of a filtration membrane and a spacer laminated together, and the spacer is a nonwoven fabric made of polyethylene fibers having a metal element content of less than 40 ppm.