Porous films with chemical resistance

• US 7,829,186 B2
• Filed: 09/15/2004
• Issued: 11/09/2010
• Est. Priority Date: 09/25/2003
• Status: Expired due to Fees

• Current Assignee: Daicel Chemical Industries Limited (Daicel Corporation)
• Original Assignee: Daicel Chemical Industries Limited (Daicel Corporation)
• Inventors: Yamato, Yo, Tsuyumoto, Michio
• Primary Examiner(s): Chang; Victor S
• Application Number:
  US10/572,548
• Publication Number:
  US 20070036959A1
• Time in Patent Office: 2,246 Days
• Field of Search: 428/304.4, 428/315.5, 428/315.7
• US Class Current: 428/304.4
• CPC Class Codes: B01D 2325/0283 Pore size
• CPC Class Codes: B01D 2325/30 Chemical resistance
• CPC Class Codes: B01D 67/0009 by phase separation, sol-gel transition, evaporation or solvent quenching
• CPC Class Codes: B01D 67/00111 Polymer pretreatment in the casting solutions
• CPC Class Codes: B01D 67/0013 Casting processes
• CPC Class Codes: B01D 67/0088 Physical treatment with compounds, e.g. swelling, coating or impregnation
• CPC Class Codes: B01D 69/02 characterised by their properties
• CPC Class Codes: B01D 71/641 Polyamide-imides
• CPC Class Codes: H01M 50/414 Synthetic resins, e.g. thermoplastics or thermosetting resins
• CPC Class Codes: H01M 50/489 Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
• CPC Class Codes: H01M 50/491 Porosity
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y10T 428/249953 Composite having voids in a component [e.g., porous, cellular, etc.]
• CPC Class Codes: Y10T 428/249978 Voids specified as micro
• CPC Class Codes: Y10T 428/249979 Specified thickness of void-containing component [absolute or relative] or numerical cell dimension

Abstract

A porous film with chemical resistance of this invention includes a porous film base covered with a chemical-resistant polymeric compound and has a multiplicity of communicating micropores having an average pore size of 0.01 to 10 μm. The chemical-resistant polymeric compound can be, for example, any of phenolic resins, urea resins, melamine resins, benzoguanamine resins, polyimide resins, epoxy resins, benzoxazine resins, polypropylene resins, polyurethane resins, fluororesins, alkyd resins, cellulose acetate resins, phthalic resins, maleic resins, and silicone resins.

Claims

1. A porous film comprising a film base and a coat of a chemical-resistant polymeric compound,

the film base produced by a phase conversion method in which mixtures containing polymers are cast as films and then introduced to solidifying liquids,

the coat of the chemical-resistant polymeric compound forming a thin solid layer over cell wall surfaces throughout the porous structure of the film base, and formed by subjecting a solution of a chemical-resistant polymeric compound or a precursor thereof dissolved in a solvent which can dissolve the polymeric compound or a precursor thereof to a coat forming procedure, with or without further subjecting the coat formed to treatment with at least one selected from the group consisting of heat, ultraviolet rays, visible radiations, electron beams, and radioactive rays,

wherein:

the porous film includes a multiplicity of communicating micropores having an average pore size of 0.01 μ

m or more and 5 μ

m or less;

an average rate of open pores inside the porous film (porosity) is 30% to 80%;

the porous film maintains the properties of the film base;

an amount of the coal of the chemical-resistant polymeric compound is 0.01 to 50 percent by weight relative to the porous film;

the film base comprises amide-imide polymers or imide polymers, and

the coat of the chemical-resistant polymeric compound comprises at least one selected from the group consisting of phenolic resins, epoxy resins, fluororesins, and ethylene/vinyl alcohol copolymers.

2. A method for producing the porous film of claim 1, comprising the steps of immersing a porous film base in a solution of a chemical-resistant polymeric compound, the porous film base comprising a multiplicity of communicating micropores having an average pore size of more than 0.01 and less than 5 μ

m, or spraying or applying the solution to the porous film base; and

drying the resulting article to cover the porous film base with the chemical-resistant polymeric compound, without immersing the porous film base in a non-solvent of the chemical-resistant polymeric compound or a precursor thereof, and without immersing the porous film base in a solution containing a non-solvent or the chemical-resistant polymeric compound or a precursor thereof, to thereby yield the porous film.

3. A method for producing the porous film of claim 1, comprising the steps of immersing a porous film base in a solution of a precursor of a chemical-resistant polymeric compound, the porous film base comprising a multiplicity of communicating micropores having an average pore size or 0.01 to 10 μ

m, or spraying or applying the solution to the porous film base;

drying the resulting article; and

subjecting the dried article to treatment with at least one selected from the group consisting of heat, ultraviolet rays, visible radiations, electron beams, and radioactive rays to cover the porous film base with the chemical-resistant polymeric compound to thereby yield the porous film.