Asahi Kasei Kogyo Kabushiki Kaisha

Asahi Kasei Kabushiki Kaisha

Asahi Kasei Chemicals Corporation

Katsuhiko Hamanaka

Koichi Yoshida

Junzo Masamoto

Toshiyuki Iwaisako

Hajime Komaki

Akihiro Watanabe

Tetsuo Shimizu

Yuzuru Ishibashi

Yoshio Kanda

In a method for producing hollow fiber membranes which comprises melt kneading a mixture comprising polyvinylidene fluoride and an organic liquid or a mixture comprising polyvinylidene fluoride, an organic liquid and an inorganic fine powder, extruding the kneaded mixture to form hollow fibers, and extracting the organic liquid or the organic liquid and the inorganic fine powder from the hollow fibers, which includes the steps of drawing the hollow fibers before or after termination of the extraction and then shrinking the fibers. According to this method, it is possible to stably produce hollow fiber membranes having dense pores and having a high water permeation performance, excellent endurance and stain resistance, and which are suitable for filtration uses such as removal of turbidity of water.

Method for producing hollow yarn film

A hollow fiber membrane cartridge wherein a cartridge head and a bottom ring are connected and fixed to each other by means of a plurality of rods or pipes, the hollow portion at the end of each hollow fiber membrane on the cartridge head side is open, the hollow portion at the end of each hollow fiber membrane on the bottom ring side is sealed, and a plurality of through-holes are provided in an adhesion and fixation layer on the bottom ring side and are located in a bundle of the hollow fiber membranes.

Hollow thread film cartridge, hollow thread film module using the cartridge, and tank type filter

Disclosed is a hollow fiber filter module comprising a cylindrical casing having a liquid introducing nozzle at least at one end portion thereof and having a bundle of hollow fibers disposed in the casing, and wherein one end portion of the bundle is enclosed by a hollow, liquid flow control member, and the liquid introducing nozzle has a specific unique structure in which the inlet opening has a larger diameter than that of the hollow of the nozzle at any portion thereof. This hollow fiber filter module can advantageously be used in the so-called external pressure type filtration on a large scale. By the use of this filter module, the external pressure type filtration of a liquid can advantageously be stably performed for a prolonged period of time with a high filtration efficiency.

Hollow fiber filter module

A method for synthesizing trioxane by heating and reacting an aqueous formaldehyde solution in the presence of a heteropolyacid. As the heteropolyacid, there is preferably used one that contains, as a coordinating element or coordinating elements, W, Mo, V or Nb alone or two or more of them.

Method for synthesizing trioxane

In a process for separating trioxane by a continuous distillation which comprises extracting, with benzene, the trioxane-containing distillate obtainable by heating an aqueous solution of formaldehyde, feeding the trioxane-containing benzene solution into a distillation column as a starting material, distilling out the benzene from the column top and withdrawing the trioxane from the column bottom, a process for separating trioxane which comprises retaining the concentration of trioxane X in the liquid composition at the starting material feeding plate of the distillation column (% by weight of trioxane based on the total liquid composition at the feeding plate) in the range satisfying the following relationship: ##EQU1## wherein R is reflux ratio, and .gamma. is a parameter defined by the following equation: ##EQU2## wherein q is the proportion of liquid part in the fed starting material as expressed in terms of ratio by weight and C (%) is the concentration of trioxane in the fed starting material.

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Fuji, Japan

Katsuhiko Hamanaka