Copolymers of maleic anhydride or acid and fluorinated oleffins

Details Copolymers of maleic anhydride or acid and fluorinated oleffins Copolymers of maleic anhydride or acid and fluorinated oleffins

2001-02-14

2002-07-23

Lipman, Bernard (Department: 1713)

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

Synthetic resins

Polymers from only ethylenic monomers or processes of...

C526S213000, C526S247000, C526S249000, C526S250000, C526S251000, C526S252000, C526S253000

Reexamination Certificate

active

06423798

ABSTRACT:

FIELD OF THE INVENTION
Novel copolymers of maleic anhydride, maleic acid, dichloromaleic anhydride or dichloromaleic acid and fluorinated olefins are prepared by free radical polymerization in a nonaqueous medium in the presence of a solvent such as a perfluorinated alkyl carboxylic acid, or liquid or supercritical carbon dioxide or hexafluoropropylene.
TECHNICAL BACKGROUND
Fluorinated polymers are important items of commerce, being particularly noted, for instance, for their thermal and chemical resistance, and their often unusual surface properties. However, sometimes these unusual properties, as for example low adhesion to substrates, are often themselves also problems in the use of these polymers, so fluorinated (co)polymers with modified properties are constantly being sought.
Although it is known that certain functional groups, especially polar functional groups, can modify the properties of fluoropolymers, incorporation of these groups into fluoropolymers without sacrificing other desirable properties is often difficult for a variety of reasons. For example the required monomers may not copolymerize with fluorinated monomers or may cause other undesirable effects in a copolymerization, or incorporation of a monomer containing a polar group may adversely affect the chemical and/or thermal stability of the resulting polymer. While it is known that maleic anhydride or maleic acid are desirable comonomers for such polymerizations, practical methods for the incorporation of these monomers into fluoropolymers have been lacking, and therefore preparation and use of such polymers has languished.
Polymers containing relatively high proportions of fluorinated olefins, especially highly fluorinated olefins, have generally been grafted with MAN (or MAN copolymers) rather than being formed by copolymerizing with the MAN, see for instance M. Miller, et al., J. Appl. Polym. Sci., vol. 14, p. 257-266 (1970), German Patent Application 4,210,594, U.S. Pat. Nos. 5,576,106, 4,506,035, Australian Patent 550,961, and European Patent Applications 761,757 and 650,987. Many of these references also describe uses for such grafted polymers which are also applicable to the polymers herein.
SUMMARY OF THE INVENTION
This invention concerns a first polymer, comprising, repeat units derived from:
(a) at least 1 mole percent hexafluoropropylene;
(b) at least 1 mole percent total of one or more of tetrafluoroethylene, vinyl fluoride, trifluoroethylene, chlorotrifluoroethylene, ethylene, and vinylidene fluoride; and
(c) 0.03 to about 5 mole percent total of one or more of maleic anhydride, maleic acid, dichloromaleic anhydride or dichloromaleic acid.
This invention also concerns a second polymer, comprising, repeat units derived from:
(a) at least 1 mole percent tetrafluoroethylene or chlorotrifluoroethylene;
(b) at least one mole percent of ethylene, a compound of the formula F
2
C═CFOR
1
wherein R
1
is alkyl or halogen substituted alkyl containing 1 to 10 carbon atoms and optionally containing one or more ether oxygen atoms between perfluoroalkylene or perfluoroalkyl segments, perfluoro(2-methylene-4-methyl-1,3-dioxolane), F
2
C═CF(CF
2
)
p
OCF═CF
2
wherein p is 1 or 2, or a compound of the formula
wherein R
8
and R
9
are each independently fluorine or perfluoroalkyl containing 1 to 4 carbon atoms; and
(c) 0.03 to about 10 mole percent of one or more of maleic anhydride, maleic acid, dichloromaleic anhydride or dichloromaleic acid.
This invention also concerns a third polymer, comprising, repeat units derived from:
(a) at least 1 mole percent vinyl fluoride, vinylidene fluoride, or chlorotrifluoroethylene; and
(b) 0.03 to about 10 mole percent of one or more of maleic anhydride, maleic acid, dichloromaleic anhydride or dichloromaleic acid.
Also disclosed herein is a process for the production of maleic anhydride, maleic acid, dichloromaleic anhydride or dichloromaleic acid copolymers with fluoroolefins by free radical polymerization in an essentially nonaqueous polymerization system, wherein the improvement comprises, using as a solvent one or more of: a compound of the formula R
6
CO
2
H wherein R
6
is perfluoroalkyl containing 1 to 6 carbon atoms, liquid or supercritical carbon dioxide, or liquid or supercritical hexafluoropropylene.
Further disclosed is a coated substrate coated with the compositions disclosed herein, a composite structure comprising the coated substrate plus an additional substrate adhered to the coated substrate and a melt blend of thermoplastic with the compositions disclosed herein.
DETAILS OF THE INVENTION
The process described herein for incorporating maleic acid (MAC), maleic anhydride (MAN), dichloromaleic anhydride (DCMAN) or dichloromaleic acid (DCMAC) (or collectively MA) in polymers derived from fluorinated olefins is similar to prior art processes for free radically polymerizing such fluorinated olefins in nonaqueous systems. Preferred monomers of MA are MAC and MAN.
By a fluorinated olefin is meant a compound in which at least one of the vinylic hydrogen atoms is replaced by a fluorine atom. Thus useful fluorinated olefins include tetrafluoroethylene (TFE), chlorotrifluoroethylene (CTFE), hexafluoropropylene (HFP), vinylidene fluoride (VF2), vinyl fluoride (VF), trifluorovinyl methyl ether, perfluoro(methyl vinyl ether) (PMVE), perfluoro(ethyl vinyl ether) (PEVE), and perfluoro(propyl vinyl ether) (PPVE), but does not include olefins such as 3,3,3-trifluoropropene and vinyl trifluoromethyl ether.
Herein, fumaric acid may be substituted, in the same required and preferred proportions, in any composition or process in which MAC is used.
By “repeat units derived from” herein is meant that the repeat units specified (and the monomers they are derived from) were incorporated into the fluoropolymer by addition polymerization, and not, for instance, by grafting. Grafting of compounds such as MAN onto already existing polymers results polymers which have a different structure. Generally the MAN moiety which is grafted onto the fluoropolymer is a side chain on the polymer, not part of the main polymer chain.
The free radically polymerized (co)polymerization of such monomers in nonaqueous systems is known, see for instance U.S. Pat. No. 5,637,663, W. Gerhartz, et al., Ed., Ullmann's Encyclopedia of Industrial Chemistry, Vol. A11, VCH Verlagsgesellschaft mbH, Weinheim, 1988, p. 393-429, and H. Mark, et al., Ed., Encyclopedia of Polymer Science and Engineering, Vol. 16, John Wiley & Sons, New York, 1989, p. 577-648, all of which are hereby included by reference. Conditions in such polymerization systems need not be changed significantly to incorporate MA into the polymer being made, just inclusion of the one (or more) of the solvents listed above and of course one or more of MAN, MAC, DCMAN or DCMAC. By a nonaqueous system is meant that a separate predominantly aqueous phase is not present in significant quantities in the polymerization process, and preferably is not present at all. Since MAC and DCMAC are soluble in water, they do not readily copolymerize with fluorinated monomers when an aqueous phase is present. Also, when water is present MAN or DCMAN is readily converted to MAC or DCMAC, respectively. Conversely, if the polymerization is carried out at higher temperatures, MAC or DCMAC may be dehydrated to MAN or DCMAC, respectively.
By a solvent in this polymerization process is meant a material which dissolves to a significant extent in the same phase the MAN and/or MAC and/or DCMAN and/or DCMAC, the other monomers, and the initiator(s). Production of the desired MA copolymer under these conditions is evidence that these solubility conditions have been met. Of course the solvent should preferably not significantly interfere with the polymerization, such as by causing excessive chain transfer or premature termination of the polymerization. It need not dissolve the product polymer to any significant extent. Thus the nonaqueous polymerization may be a true solution polymerization in which all of the components and the product polymer are soluble in

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