Polyvinylidene difluoride structure

• US 4,774,132 A
• Filed: 05/01/1986
• Issued: 09/27/1988
• Est. Priority Date: 05/01/1986
• Status: Expired due to Term

• Current Assignee: Pall Corporation (Danaher Corporation)
• Original Assignee: Pall Corporation (Danaher Corporation)
• Inventors: Degen, Peter J., Joffee, Irving B., Baltusis, Frederick A.
• Primary Examiner(s): SECCURO JR, CARMAN J
• Application Number:
  US06/857,945
• Time in Patent Office: 880 Days
• Field of Search: 428/304.4, 428/290
• US Class Current: 428/304.4
• CPC Class Codes: B01D 2323/38 Graft polymerization
• CPC Class Codes: B01D 39/1623 of synthetic origin
• CPC Class Codes: B01D 67/00931 by introduction of specific groups after membrane formation, e.g. by grafting
• CPC Class Codes: B01D 71/34 Polyvinylidene fluoride
• CPC Class Codes: C08J 2327/16 Homopolymers or copolymers of vinylidene fluoride
• CPC Class Codes: C08J 7/16 with polymerisable compounds
• CPC Class Codes: Y10T 428/249953 Composite having voids in a component [e.g., porous, cellular, etc.]
• CPC Class Codes: Y10T 428/3154 Of fluorinated addition polymer from unsaturated monomers

Abstract

A polyvinylidene difluoride structure with a critical surface energy of at least about 80 dynes/cm and a method of making such a structure comprising the steps of contacting a polyvinylidene difluoride structure with an alkalized solution, such as potassium hydroxide, to form activated sites on the surface of the structure; rinsing the activated structure to remove residual alkali; contacting the rinsed, activated structure with a solution of a polymerization initiator, such as potassium peroxydisulfate, and a polymerizable vinylic monomer, such as acrylic acid; and polymerizing and grafting the monomer to the activated structure to form a polyvinylidene difluoride structure with a critical surface energy of at least about 80 dynes/cm.

Claims

1. A polyvinylidene difluoride structure with a high critical surface energy comprising a polyvinylidene difluoride porous membrane or fibrous web substrate having grafted thereto a polymer derived at least in part from polymerizable vinylic monomer having the formula:

##STR3## wherein R is H, an aminoalkyl or quaternized aminoalkyl group having 1 to 3 carbon atoms, or a hydroxy alkyl group having 1 to 3 carbon atoms;

R'"'"', R" and R"'"'"' independently are H, and alkyl group having 1 to 3 carbon atoms, a carboxyl group (--COOH), a carboxyalkyl group having 1 to 3 carbon atoms, or a hydroxyalkyloxycarbonyl group having 1 to 3 carbon atoms, said polymer including functional groups sufficiently polar or ionic that said structure has a critical surface energy of at least about 80 dynes/cm and said polyvinylidene difluoride substrate prior to grafting having activated sites formed on the surface.

2. The structure of claim 1 wherein said structure is a microporous membrane having a pore rating of from about 0.01 to about 2 micrometers.

3. The structure of claim 2 wherein said structure is a microporous membrane having a pore rating of from about 0.04 to about 1.5 micrometers.

4. The structure of claim 1 wherein said monomer is selected from the class consisting of acrylic acid, methacrylic acid, itaconic acid, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-trimethylammonioethyl acrylate chloride, and mixtures thereof.

5. A microporous polyvinylidene difluoride membrane with a high critical surface energy comprising a polyvinylidene difluoride substrate having grafted thereto a polymer derived at least in part from acrylic acid, said membrane having a pore rating in the range of from about 0.04 to about 2 micrometers and a critical surface energy of at least about 80 dynes/cm and said polyvinylidene difluoride substrate prior to grafting having activated sites formed on the surface.

6. The membrane of claim 5 wherein said critical surface energy is at least about 85 dynes/cm.

7. The membrane of claim 6 wherein said membrane is in the form of a disc or cartridge.