Applying a fluoropolymer film to a body

• US 5,773,098 A
• Filed: 11/21/1995
• Issued: 06/30/1998
• Est. Priority Date: 06/20/1991
• Status: Expired due to Term

• Current Assignee: British Technology Group Ltd. (Boston Scientific Corporation)
• Original Assignee: British Technology Group Ltd. (Boston Scientific Corporation)
• Inventors: Thomas, Thomas Ronald
• Primary Examiner(s): DUDASH, DIANA L
• Application Number:
  US08/561,384
• Time in Patent Office: 952 Days
• Field of Search: 427/490, 427/245, 427/255.6, 427/255.1, 427/534, 427/535, 427/536, 427/538, 427/307, 427/296, 427/322
• US Class Current: 427/490
• CPC Class Codes: B01D 69/127 using electrical discharge or plasma-polymerisation
• CPC Class Codes: B01D 71/32 containing fluorine atoms
• CPC Class Codes: B01D 71/36 Polytetrafluoroethene
• CPC Class Codes: B05D 1/62 Plasma-deposition of organic layers plasma deposition in general C23C14/00, C23C16/00
• CPC Class Codes: B05D 3/144 of polymeric substrates
• CPC Class Codes: C08J 2327/18 Homopolymers or copolymers of tetrafluoroethylene
• CPC Class Codes: C08J 7/123 Treatment by wave energy or particle radiation C08J7/18 takes precedence
• CPC Class Codes: D06M 10/025 Corona discharge or low temperature plasma
• CPC Class Codes: D06M 10/10 Macromolecular compounds
• CPC Class Codes: D06M 14/34 Polyamides
• CPC Class Codes: D06M 15/256 containing fluorine
• CPC Class Codes: D06M 2101/22 Polymers or copolymers of halogenated mono-olefins
• CPC Class Codes: D06M 2400/01 Creating covalent bondings between the treating agent and the fibre
• CPC Class Codes: D21H 17/11 Halides
• CPC Class Codes: D21H 21/16 Sizing or water-repelling agents
• CPC Class Codes: D21H 23/44 Treatment with a gas or vapour
• CPC Class Codes: D21H 25/06 of impregnated or coated paper D21H25/08 takes precedence

Abstract

A thin fluoropolymer film is covalently bonded to a microporous ptfe film to make a bilayer for separation, filtration or reverse osmosis, by exposing the microporous film to perfluorocyclohexane under plasma. The perfluorocyclohexane molecules undergo scission and the fragments combine on the substrate to make a fluoropolymer film wherein the pores of the substrate have not been completely closed by the coating.

Claims

1. A method of applying a fluoropolymer film to a porous or microporous body, comprising exposing the body to a supply of saturated molecules of the formula C_n F_2n, where n=4-8, causing scission of the molecules, and allowing the fragments to combine on the surface of the body to form an adherent fluoropolymer layer, and ceasing exposure of the body to the supply of saturated molecules before the pores of the body have been completely closed by the deposited fluoropolymer.

2. A method of applying a fluoropolymer film according to claim 1 wherein the porous body is a carbonaceous polymer, and the fragments combine on the surface of the body to form a fluoropolymer layer covalently bonded to the body.

3. A method according to claim 1, wherein the carbonaceous polymer is a fluoropolymer.

4. A method according to claim 1, wherein the body is itself a film.

5. A method according to claim 4, wherein the body is a microporous film.

6. A method according to claim 1, wherein the molecules are of cycloperfluoroalkane.

7. A method according to claim 6, wherein the molecules are of cyclo-C_n F_2n where n=4, 5, 7 or 8.

8. A method according to claim 6, wherein the molecules are of cycloperfluorohexane.

9. A method according to claim 1, wherein the porous body is etched before the application of said film thereto.

10. A method according to claim 1, wherein the body is subjected to plasma irradiation during its exposure.

11. A method according to claim 10, wherein the plasma power is less than 100 W.

12. A method according to claim 11, wherein the plasma power is from 0.1 to 50 W.

13. A method according to claim 11 or 12, wherein the plasma power is less than 5 W.

14. A method according to claim 1, performed in a chamber evacuated to 0.01 to 5 torr.

15. A method according to claim 9, wherein the etching is performed by a noble gas plasma.