Compositions for bonding fluoroplastics

Details Compositions for bonding fluoroplastics Compositions for bonding fluoroplastics

1998-12-08

2001-08-07

Chen, Vivian (Department: 1773)

Stock material or miscellaneous articles

Composite

Of fluorinated addition polymer from unsaturated monomers

C428S515000, C428S519000, C428S520000, C428S521000, C428S522000

Reexamination Certificate

active

06270901

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to multilayer compositions comprising a fluoropolymer and curable elastomers. In another aspect, this invention relates to the use of certain epichlorohydrin (ECO) and nitrile-butadiene (NBR) elastomer compositions for improved bonding to vinylidene fluoride containing fluoropolymer materials.
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).
Multilayer constructions containing a fluorinated polymer enjoy wide industrial application; multilayer 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 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 multilayered 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 (Ueno 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).
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).
As the above discussion illustrates, the combined features of hydrocarbon elastomer compounds and fluoropolymer materials are a desirable combination. This patent addresses a means for improving the adhesion between these dissimilar polymers.
SUMMARY OF THE INVENTION
In one aspect, this invention relates to a method of bonding a fluoroplastic comprising interpolymerized units derived from vinylidene fluoride to a curable elastomer comprising the steps of: a) providing; (i) a fluoroplastic comprising interpolymerized units derived from vinylidene fluoride or those monomers that result in a polymer microstructure similar to a polymer derived from vinylidene fluoride, (ii) a curable elastomer, and (iii) a dehydrofluorinating composition; b) forming a mixture comprising the curable elastomer and an effective amount of the dehydrofluorinating composition; c) contacting the mixture with the fluoroplastic to form a multilayer article; and d) curing the multilayer article for a time and at a temperature sufficient to provide an interlayer adhesion between the curable elastomer layer and the fluoroplastic layer of a higher value than without the dehydrofluorinating composition.
In another aspect, this invention relates to a layered article comprising a first layer comprising a fluoroplastic comprising interpolymerized units derived from vinylidene fluoride or those monomers that result in a polymer microstructure similar to a polymer derived from vinylidene fluoride, said first layer is in substantial contact with a second layer comprising a mixture of a curable elastomer and a dehydrofluorinating composition. Such layered articles may include films, gaskets, tubes or hoses, and containers.
The layers discussed herein are intended to include the concept of a surface, such as that found when constructing a multilayered hose or other shaped article and not intended to be limited to flat shapes. Thus, a first layer or surface may be formed or shaped prior to application of the second material. The substantial contact of the second material to the first is to a surface of the first material. Either the fluoropolymer component or the curable elastomer component may be formed or shaped first. When a shaped article, such as a hose, is formed, either material may be on the inside or the outside of the article depending upon the intended use, such as where the temperature resistance or chemical resistance is most needed.
Curable elastomers may be selected from the group consisting of epichlorohydrin-containing elastomers, nitrile-butadiene rubbers, fluorinated elastomers, silicone-containing elastomers, ethylene propylene diene monomer-containing elastomers and combinations thereof.
Specific dehydrofluorinating compositions may be selected from the group consisting of organo-oniums, amidines, such as 1,8-diazabicyclo[4.3.0]undec-7-ene(DBU) and 1,5-diazabicyclo[4.3.0]non-5-ene(DBN), salts of amidines and combinations thereof.
A fluoroplastic which is a copolymer comprising interpolymeriz

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