Stock material or miscellaneous articles – Composite – Of fluorinated addition polymer from unsaturated monomers
Reexamination Certificate
1997-12-19
2002-11-19
Pyon, Harold (Department: 1772)
Stock material or miscellaneous articles
Composite
Of fluorinated addition polymer from unsaturated monomers
C428S422000, C428S035700
Reexamination Certificate
active
06482522
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to multi-layer compositions comprising a fluoropolymer and a curable elastomer as well as to methods of producing same. In another aspect, this invention relates to methods of improving the adhesion between a fluoropolymer and other dissimilar materials, such as, epichlorohydrin and nitrile-butadiene elastomers.
BACKGROUND OF THE INVENTION
Fluorine-containing polymers (i.e., fluoropolymers or fluorinated polymers), are an important class of polymers that include, for example, fluoroelastomers and fluoroplastics. Among this broad polymer class are polymers of high thermal stability, polymers of extreme toughness, and polymers exhibiting usefulness along a broad range of temperatures. Many of these polymers also are almost totally insoluble in a wide variety of organic solvents; see, for example, F. W. Billmeyer,
Textbook of Polymer Science
, 3rd ed., pp. 398-403, John Wiley & Sons, New York (1984).
Fluoroelastomers, particularly the copolymers of vinylidene fluoride with other ethylenically unsaturated halogenated monomers such as hexafluoropropene, find particular utility in high temperature applications, such as in seal gaskets and linings. See, for example, Brullo, R. A., “Fluoroelastomer Rubber for Automotive Applications,”
Automotive Elastomer
&
Design
, June 1985, “Fluoroelastomers Seal Up Automotive Future,”
Materials Engineering
, October 1988, and Grootaert, W. M., Millet, G. H., Worm, A. T., “Fluorocarbon Elastomers,” Kirk-Othmer,
Encyclopedia of Chemical Technology
, 4th ed., Vol. 8, pp. 990-1005, John Wiley & Sons, New York (1993).
Fluoroplastics, particularly polychlorotrifluoroethylene, polytetrafluoroethylene, copolymers of tetrafluoroethylene and hexafluoropropylene, and poly(vinylidene fluoride), have numerous electrical, mechanical, and chemical applications. Fluoroplastics are useful, for example, as wire coatings, electrical components, seals, and in solid and lined pipes and piezoelectric detectors. See, for example, “Organic Fluorine Compounds,” Kirk-Othmer,
Encyclopedia of Chemical Technology
, Vol. 11, pp. 20, 21, 32, 33, 40, 41, 48, 50, 52, 62, 70, and 71, John Wiley & Sons, New York (1980).
Multi-layer constructions containing a fluorinated polymer enjoy wide industrial application; multi-layer fluoropolymer constructions find utility in, for example, fuel line hoses and related containers and hoses or gaskets in the chemical processing field. Increased concerns with evaporative fuel standards give rise to a need for fuel system components that have increased barrier properties to minimize the permeation of fuel or fuel vapors through automotive components, such as fuel filler lines, fuel supply lines, fuel tanks, and other components of the engine's fuel or vapor recovery systems. Various types of tubing have been proposed to address these concerns.
Adhesion between the layers of a multi-layered article may need to meet various performance standards depending on the use of the finished article. A variety of methods can be used to increase the adhesion between a fluorinated polymer layer and a non-fluorinated polymer layer. An adhesive layer can, for example, be added between the two polymer layers. U.S. Pat. No. 5,047,287 (Horiuchi et al.) discloses a diaphragm, suitable for use in automotive applications, that comprises a base fabric having bonded to at least one surface a fluororubber layer by an adhesive that includes an acrylonitrile-butadiene or acrylonitrile-isoprene rubber having an amino group. Blends of the fluoropolymer and the non-fluorinated polymer layer themselves are in some cases employed as an intermediate layer to help bond the two layers together. European Patent Application 0523644 (Kawashima et al.) discloses a plastic laminate having a polyamide resin surface layer and a fluororesin surface layer. The reference recognizes the difficulties encountered when making laminates having a polyamide layer and a fluororesin layer because of the incompatibility of the two materials. The laminate of the reference is prepared by use of an intermediate layer composed of a blend of an aliphatic polyamide resin with a fluorine-containing graft copolymer. U.S. Pat. No. 5,242,976 (Strassel et al.) discloses co-extruding vinylidene polyfluoride with an alkyl polymethacrylate and vinylidene polyfluoride composition.
Surface treatment of one or both of the layers sometimes is employed to aid bonding. Some, for example, have taught treating fluoropolymer layers with charged gaseous atmosphere and applying subsequently a layer of a second material, for example a thermoplastic polyamide. E.g., European Patent Applications 0185590 ((Jeno et al.) and 0551094 (Krause et al.) and U.S. Pat. No. 4,933,060 (Prohaska et al.) and U.S. Pat. No. 5,170,011 (Martucci).
Numerous methods of bonding have been proposed for multi-layer constructions where the fluoropolymer layer contains a molecular structure resulting from the inclusion of a vinylidene fluoride (VDF) or similar monomer unit. Similar monomers in this sense mean those monomers other than VDF which when polymerized, form monomer sequences similar to polymerized vinylidene fluoride. In general, these fluoropolymers will readily dehydrofluorinate when exposed to a base. As a result, such fluoropolymers undergo relatively facile adhesion promoting reactions. These other such monomers include ethylenically unsaturated monomers which, when incorporated into fluoropolymers, can produce a similar (including an identical) polymeric microstructure as the polymerized VDF. These similarly formed polymers are also prone to dehydrofluorination and subsequent adhesion promoting reactions. In general, the microstructure of a hydrogen bonded carbon atom between fluorine bonded carbon atoms creates a site reactive to a base. The reactivity of a hydrogen bonded carbon is further enhanced when its carbon atom is adjacent to, or attached to a carbon atom possessing a carbon bonded —CF3 group (supplied by HFP or 2-hydropentafluoropropylene for instance) or another electron withdrawing group. Monomers suitable for forming such hydrogen-bonded-carbon reactive sites include, but are not limited to, VDF, 1-hydropentafluoropropene, 2-hydropentafluoropropene, and trifluoroethylene.
The addition of a primary amine containing unsaturated compound to a hydrocarbon elastomer layer is disclosed as a method for increasing the adhesion to a layer comprising fluoropolymer comprising interpolymerized units derived from vinylidene fluoride in U.S. Pat. No. 5,512,225 (Fukushi).
SUMMARY OF THE INVENTION
Multi-layer constructions containing a fluoropolymer without the VDF segment or a similar easily dehydrofluorinated segment as discussed above and below, are much more difficult to make with adequate interlayer bond strength. These types of construction are desirable however, because fluoropolymers without a segment readily susceptible to dehydrofluorinating are more chemically inert. For example, tubes or hoses or other containers used in fuel or chemical applications where inertness, permeation reduction and interlayer adhesion improvement are important, will benefit from the improvement described in this invention.
As the above discussion illustrates, the combined features of curable elastomer compounds and fluoropolymer materials are a desirable combination, particularly when the fluoropolymer possesses improved chemical resistance or permeation properties.
In one aspect, this invention relates to a method of bonding a fluoropolymer to a curable elastomer comprising the steps of: a) providing; (i) a fluoropolymer layer comprising a fluorine-containing polymer derived from interpolymerized units of at least one fluorine-containing olefinically unsaturated monomer, with the proviso that if a perfluorinated monomer is present then at least one monomer that contains hydrogen atoms is also present and with the further proviso that the monomer(s) include neither vinylidene fluoride nor a monomer which when polymerized forms a micro structure similar to polymerized vinylidene fluoride, (ii)
Kolb Robert E.
Parsonage Edward E.
Dyneon LLC
Harts Dean M.
Lilly James V.
Miggins Michael C.
Pyon Harold
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