Abstract: A method of producing a porous sheet, which comprises the steps consisting of preparing a dispersion having ultra-high-molecular-weight polyethylene particles dispersed in a solvent, applying the dispersion onto a film to form a coating layer thereon, sintering the coating layer, and removing the solvent contained in the coating layer.

Abstract: Provided is a method of manufacturing a porous polytetrafluoroethylene (PTFE) membrane capable of achieving both a high collection efficiency and a low pressure drop, though it has a larger average pore size and a greater thickness than conventional porous PTFE membranes. This manufacturing method includes: stretching an unsintered polytetrafluoroethylene sheet by a factor of 5 to 30 in a predetermined direction at a temperature equal to or higher than the melting point of polytetrafluoroethylene; further stretching the stretched sheet by a factor of 5 to 40 in a direction different from the predetermined direction at a temperature lower than the melting point; and after the stretchings, heating the stretched sheet at a temperature equal to or higher than the melting point.

Abstract: The present invention provides a sheet roll of a porous polytetrafluoroethylene membrane in which during production a winding-up operation is easy and a cutting operation also is easy, as well as a tape roll of a porous polytetrafluoroethylene membrane that is difficult to lose its shape. The present invention provides a sheet roll comprising a laminate of a porous polytetrafluoroethylene membrane and a support, wherein the laminate is wound up, as well as a tape roll comprising a laminate of a porous polytetrafluoroethylene membrane and a support, wherein the laminate is wound up. The latter tape roll can be obtained by cutting the former sheet roll.

Abstract: Provided is a method of manufacturing a porous polytetrafluoroethylene (PTFE) membrane capable of achieving both a high collection efficiency and a low pressure drop, though it has a larger average pore size and a greater thickness than conventional porous PTFE membranes. This manufacturing method includes: stretching an unsintered polytetrafluoroethylene sheet by a factor of 5 to 30 in a predetermined direction at a temperature equal to or higher than the melting point of polytetrafluoroethylene; further stretching the stretched sheet by a factor of 5 to 40 in a direction different from the predetermined direction at a temperature lower than the melting point; and after the stretchings, heating the stretched sheet at a temperature equal to or higher than the melting point.

Abstract: A method of producing a porous sheet, which comprises the steps consisting of preparing a dispersion having ultra-high-molecular-weight polyethylene particles dispersed in a solvent, applying the dispersion onto a film to form a coating layer thereon, sintering the coating layer, and removing the solvent contained in the coating layer.

Abstract: A method of storing processed fish and processed roe which comprises placing processed fish or processed roe in a gas impermeable packing bag or an airtight container together with an oxygen absorbent and leaving the same to stand at a temperature between -20.degree. and 25.degree. C. is disclosed. This invention permits storage processed fish or processed roe containing little salt, or processed fish or processed roe containing much water.