A microporous membrane has average membrane thickness of 15 m or less, and relative impedance A after a heat compression treatment under a pressure of 4.0 MPa at 80 C. for 10 minutes of 140% or less, the relative impedance A being obtained by the equation below: Relative impedance A=(impedance measured at 80 C. after the heat compression treatment)/(impedance measured at room temperature prior to the heat compression treatment)100.

A film-stretching apparatus in accordance with an embodiment of the present invention includes a stretching furnace which is divided into a plurality of air amount control zones. In a case where the number of the plurality of air amount control zones is seven, a total amount of air to be discharged from, out of the plurality of air amount control zones, three air amount control zones which are located on an entrance side of the stretching furnace is controlled so as to be larger than a total amount of air to be discharged from, out of the plurality of air amount control zones, three air amount control zones which are located on an exit side of the stretching furnace.

The purpose of the present invention is to provide a porous molded body which is capable of adsorbing and removing low-molecular-weight organic matters or ions with high removal rate. The present invention relates to a porous molded body which is provided with: a plurality of columnar structures containing a crystalline polymer and having a (long side)/(short side) aspect ratio of 2 or more; and inorganic particles.

A film-stretching apparatus in accordance with an aspect of the present invention includes a stretching furnace which has (i) an entrance through which a material film is transferred into the stretching furnace and (ii) an exit through which the material film having been stretched is transferred out of the stretching furnace, an airflow in the entrance being controlled so as to be directed toward an outside of the stretching furnace.

A method for forming porous fibers is provided. The fibers are formed from a thermoplastic composition containing a continuous phase, which includes a matrix polymer, and a nanoinclusion additive that is at least partially incompatible with the matrix polymer so that it becomes dispersed within the continuous phase as discrete nano-scale phase domains. The method includes traversing a bundle of the fibers through a multi-stage drawing system that includes at least a first fluidic drawing stage and a second fluidic drawing stage. The first drawing stage employs a first fluidic medium having a first temperature and the second drawing stage employs a second fluidic medium having a second temperature. The first and second temperatures are both lower than the melting temperature of the matrix polymer, and the first temperature is greater than the second temperature.

A polyolefin microporous membrane has excellent strength, permeability and heat resistance, which is obtained by using UHMwPE and employing a sequential stretching system, and a production method of the microporous membrane. In producing a microporous membrane by using a primary material A having a molecular weight (Mw) of less than 1.0?10.sup.6, a secondary material B having a molecular weight of 1.0?10.sup.6 or more, and a plasticizer, when the endothermic quantity of a mixture of the primary material and the plasticizer and the endothermic quantity of a mixture of the secondary material and the plasticizer are denoted as Q1 and Q2, respectively, respective resins are designed such that the ratio of endothermic quantity Q2 to endothermic quantity Q1 (endothermic quantity Q2/endothermic quantity Q1) becomes 1 or more over a temperature range of 110 to 118? C.

A polymeric fiber for use in gas separation is formed from a spin dope which includes solvent and non-solvent materials. The fiber is passed through a quench bath, and then a leach bath, in which the solvent and non-solvent are removed. The quench bath and the leach bath include sets of rollers which transport the fiber through the system. Each set of rollers in the leach bath operates at a speed which is greater than or equal to the speed of the rollers which are immediately upstream. Thus, the fiber is stretched, in different amounts, at the same time that the solvent and non-solvent are being removed, and while the fiber is still wet. The resulting fiber has been found to exhibit superior flux and selectivity properties.

A film-stretching apparatus in accordance with an aspect of the present invention includes a stretching furnace which has (i) an entrance through which a material film is transferred into the stretching furnace and (ii) an exit through which the material film having been stretched is transferred out of the stretching furnace, an airflow in the entrance being controlled so as to be directed toward an outside of the stretching furnace.

A film-stretching apparatus in accordance with an embodiment of the present invention includes a stretching furnace which is divided into a plurality of air amount control zones. In a case where the number of the plurality of air amount control zones is seven, a total amount of air to be discharged from, out of the plurality of air amount control zones, three air amount control zones which are located on an entrance side of the stretching furnace is controlled so as to be larger than a total amount of air to be discharged from, out of the plurality of air amount control zones, three air amount control zones which are located on an exit side of the stretching furnace.

Disclosed is a method of producing a microporous polymer membrane, comprising: providing a polymer material; melting the polymer material; forming a precursor film by cooling and crystallizing the molten polymer material using an air knife; extending the precursor film; annealing the extended precursor film, primary stretching the annealed precursor film; forming a preliminary membrane by subjecting the primary stretched film to secondary stretching at a high temperature, and forming a microporous polymer membrane by heat setting the preliminary membrane. A microporous polymer membrane produced by the method is also provided.