Fluoropolymer adhesion

Details Fluoropolymer adhesion Fluoropolymer adhesion

1998-01-08

1999-08-10

Michl, Paul R.

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Processes of preparing a desired or intentional composition...

C08K 900

Patent

active

059360097

DESCRIPTION:

BRIEF SUMMARY
FIELD OF THE INVENTION

This invention concerns a process for the improvement of adhesion between fluoropolymers or fluorocopolymers and inorganic compounds and to composite materials made by this process.


TECHNICAL BACKGROUND

Various approaches have been used in the past in attempts to increase the adhesion between fluoropolymers and substrates or filler materials.
U.S. Pat. No. 3,787,281, Effenberger, discloses a process for bonding polytetrafluoroethylene to glass, fibers or plates, using a hydrolyzable silane or a methacrylato chromic chloride as bonding agent.
Canadian Patent No. 764,537 Bowman, discloses adhesive compositions suitable for use with fluorocarbon polymers comprising reactive (hydrolyzable) silanes or siloxanes. The fluorocarbon polymer is optionally pretreated with a solution of sodium in ammonia or a solution of sodium naphthalene in tetrahydrofuran.
U.S. Pat. No. 3,804,802, Bergna, discloses composites of thermoplastic resins, including polyfluoroolefins, with glass fiber materials utilizing a nitrate-containing coupling agent to increase adhesion between the components.
U.S. Pat. Nos. 4,902,444 and 5,000,875 disclose melt processable fluorinated tetrafluoroethylene copolymer and terpolymer compositions that are treated with a fluorinating agent to remove unstable end groups, then compounded with electrically conductive agents or thermally conductive fillers.
U.S. Pat. No. 5,024,871, Arthur, discloses a ceramic-filled fluoropolymeric composite wherein the filler, preferably fused amorphous silica, is coated with a zirconate or titanate coating. Said composite possesses excellent thermal, mechanical and electrical properties. U.S. Pat. Nos. 5,061,548 and 5,384181, Arthur, disclose similar composites wherein the surface coating agent is a silane.


SUMMARY OF THE INVENTION

This invention provides a process for the improvement of adhesion between fluoropolymers or fluorocopolymers and inorganic compounds comprising the steps of 1) contacting the inorganic compound with an adhesion promoter to form a coated inorganic compound, 2) contacting the coated inorganic compound with the fluoropolymer or fluorocopolymer and 3) heating the coated inorganic compound-contacted, fluoropolymer or fluorocopolymer to a temperature sufficient to convert the adhesion promoter to a carbon-rich char.
This invention also includes composite materials made by the process. These composites of an inorganic compound and a fluoropolymer or fluorocopolymer have an interfacial layer of carbon-rich char which improves the adhesion of the inorganic compound to the fluoropolymer or fluorocopolymer.


BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic drawing of a sandwich specimen and the double cantilevered beam (DCB) experimental setup.
FIG. 2 shows adhesion level (G) as a function of lamination temperature for Teflon.RTM. PFA 350 on Pyrex.RTM. glass.
FIG. 3 shows adhesion level (G) as a function of lamination temperature for Tefzel.RTM. 280 on Pyrex.RTM. glass.


DETAILED DESCRIPTION OF THE INVENTION

The process of the present invention concerns a process for the improvement of adhesion between fluoropolymers or fluorocopolymers and inorganic compounds.
Fluoropolymers or fluorocopolymers, hereinafter generally referred to as fluorochemicals, usable in the process of the present invention include poly(tetrafluoroethylene), PTFE (Teflon.RTM.); tetrafluoroethylene-hexafluoro-propylene copolymer, also referred to as fluorinated ethylene-propylene copolymer, FEP (Teflon.RTM. FEP); ethylene-tetrafluoroethylene copolymer, ETFE (Tefzel.RTM.); perfluoroalkoxy modified tetrafluoroethylenes, PFA, e.g., tetrafluoro-ethylene-perfluoropropylvinylether copolymer (Teflon.RTM. PFA); poly(chlorotri-fluorotetrafluoroethylene), PCTFE; vinylidene fluoride-tetrafluoroethylene copolymer, VF2-TFE; poly(vinylidene fluoride), (Kynar.RTM.); and tetrafluoro-ethylene-perfluorodioxole copolymers, (Teflon AF.RTM.). Included in the group of fluoroelastomers which are fluoropolymers or fluorocopolymers are vinylidene fluoride-hexafluoropro

REFERENCES:
patent: 3674689 (1972-07-01), Giltrow et al.
patent: 3787281 (1974-01-01), Effenberger
patent: 3804802 (1974-04-01), Bergna
patent: 4902444 (1990-02-01), Kolouch
patent: 5000875 (1991-03-01), Kolouch
patent: 5024871 (1991-06-01), Arthur et al.
patent: 5061548 (1991-10-01), Arthur et al.
patent: 5384181 (1995-01-01), Arthur et al.
Arkles, B.C. et al., "Wear Characteristics of Fluoropolymer Composites", Polym. Sci. Technol, 5B (Adv. Polym. Frict. Wear), 5B, pp. 663-688, 1974.
Brydson, J.A., Plastics Materials, 5th Ed., pp. 359-360, 1989.

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