Porous polyvinylidene fluoride resin film and process for producing the same

• US 6,299,773 B1
• Filed: 12/16/1999
• Issued: 10/09/2001
• Est. Priority Date: 06/22/1998
• Status: Expired due to Term

• Current Assignee: Asahi Kasei Kabushiki Kaisha
• Original Assignee: Asahi Kasei Kogyo Kabushiki Kaisha
• Inventors: Yoshida, Hitoshi, Takamura, Masakazu
• Primary Examiner(s): FORTUNA, ANA M
• Application Number:
  US09/445,955
• Time in Patent Office: 663 Days
• Field of Search: 210/500.42, 210/500.23, 264/41, 264/177.14, 264/184
• US Class Current: 210/500.23
• CPC Class Codes: B01D 2323/08 Specific temperatures applied
• CPC Class Codes: B01D 2323/081 Heating
• CPC Class Codes: B01D 2323/12 Specific ratios of components used
• CPC Class Codes: B01D 2323/18 Pore-control agents or pore formers
• CPC Class Codes: B01D 2325/04 Characteristic thickness
• CPC Class Codes: B01D 2325/22 Thermal or heat-resistance properties
• CPC Class Codes: B01D 2325/24 Mechanical properties, e.g. strength
• CPC Class Codes: B01D 67/0011 Casting solutions therefor
• CPC Class Codes: B01D 67/00111 Polymer pretreatment in the casting solutions
• CPC Class Codes: B01D 67/00113 Pretreatment of the casting solutions, e.g. thermal treatment or ageing
• CPC Class Codes: B01D 67/002 from melts
• CPC Class Codes: B01D 67/0027 by stretching
• CPC Class Codes: B01D 69/02 characterised by their properties
• CPC Class Codes: B01D 69/08 Hollow fibre membranes manufacture of hollow fibres D01D5/24, D01F1/08
• CPC Class Codes: B01D 69/081 characterised by the fibre diameter
• CPC Class Codes: B01D 69/087 Details relating to the spinning process
• CPC Class Codes: B01D 69/0871 Fibre guidance after spinning through the manufacturing apparatus
• CPC Class Codes: B01D 69/141 Heterogeneous membranes, e.g. containing dispersed material; Mixed matrix membranes
• CPC Class Codes: B01D 69/1411 containing dispersed material in a continuous matrix
• CPC Class Codes: B01D 71/34 Polyvinylidene fluoride
• CPC Class Codes: D01D 5/24 : with a hollow structure; Spinnerette packs therefor D01D5/38 takes precedence; producing tubes of plastic material B29D; addition of agents forming hollow filaments D01F1/08
• CPC Class Codes: D01F 1/08 : for forming hollow filaments
• CPC Class Codes: D01F 6/12 : from polymers of fluorinated hydrocarbons

Abstract

A porous hollow fiber polyvinylidene fluoride resin membrane, characterized in that the membrane has a unitary three-dimensional network structure entirely composed of a polyvinylidene fluoride resin and has an inside diameter of 1.5-5 mm and a wall thickness of 0.5-2 mm and in that the relationship between membrane bubble point and water flux per unit wall thickness is on or above the curve shown in FIG. 1.

Claims

1. A porous hollow fiber polyvinylidene fluoride resin membrane, characterized in that the membrane has a unitary, three-dimensional, network pore structure composed entirely of a polyvinylidene fluoride resin and has an inside diameter of 1.5-5 mm and a wall thickness of 0.5-2 mm and wherein the relationship between membrane bubble point and water flux per unit wall thickness is on or above the curve shown in FIG. 1, wherein the bubble point is expressed as a multiple of unit 0.1 Mpa and the water flux per unit wall thickness is expressed as 1/m/hr/0.1 Mpa at 25°

C.

2. A process for producing a porous hollow fiber polyvinylidene fluoride resin membrane, which comprises blending a polyvinylidene fluoride resin with an organic liquid and an inorganic particulate material, heat melting the resulting blend at a temperature of 60°

C. or more above the melting point of the resin by using a melt molded extruder equipped with an annular hollow fiber spinning die nozzle, extruding the molten blend in the form of a hollow fiber, passing the resultant hollow fiber-shaped extrudate through the air and taking up said extrudate.

3. The process according to claim 2, wherein said extrudate is passed through the air for a distance of from 20 to 150 cm.