Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
2000-07-10
2004-01-20
Wu, David W. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C524S544000, C524S545000, C524S546000, C524S458000, C526S254000, C526S255000, C525S276000
Reexamination Certificate
active
06680357
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to fluoropolymers, more specifically to fluoropolymers based on vinylidene fluoride (VDF), still more specifically to polymers based on polyvinylidene fluoride (PVDF), still more specifically to PVDF homopolymers and to PVDF-based polymers having incorporated therein residues derived from monomers capable of copolymerization with VDF, particularly residues derived from hexafluoropropylene (HFP) or PVDF/HFP copolymers, still more particularly to polymers where PVDF-based polymer particles, particularly, PVDF homopolymer and/or PVDF/HFP copolymer particles, are employed as seed in a polymerization of acrylic-type polymers from acrylic-type monomers and monomers copolymerizable with acrylic-type monomers to form what will be referred to herein as “AMF polymers,” still more specifically to AMF polymers containing in the acrylic portion thereof functional groups capable of reacting with other functional groups in the acrylic portions of other AMF polymers with or without the aid of separate crosslinking aids to form crosslinked AMF polymers, to processes for the preparation and use of such polymers, to compositions containing the uncrosslinked polymers and compositions and articles of manufacture which comprise the crosslinked polymers.
DISCLOSURE OF PRIOR ART
Commercially successful vehicles for paints, films, and the like to form coatings for substrates based on VDF homo- and copolymers for many years were based on the inclusion of a portion of acrylic polymers to aid inter alia in adhesion of the coating to the substrate and wetting and binding of the pigment.
The VDF polymer or copolymer and the acrylic polymer were prepared separately and simply blended by known techniques with the pigment and any other desired ingredients to form the composition used to form the coating.
In recent years, attempts have been made to prepare AMF polymers because of various advantages thought to be embodied in that approach to PVDF homopolymer and copolymer based coatings.
Also, thermosetting acrylics are well known in the literature for increasing physical and mechanical properties as well as solvent and mar resistance for the acrylic polymer over corresponding non-thermosetting acrylics. Thermosetting can be achieved by many means, such as, Diels Alder additions, auto-oxidation, free radical coupling, condensation and transesterification. Phase separation of incompatible polymers can also be reduced through internal crosslinks.
U.S. Pat. No. 5,349,003 discloses aqueous dispersions of vinylidene fluoride based polymers employed as seeds in acrylic polymer synthesis to prepare aqueous dispersions of AMF polymers.
The PVDF polymers may be homopolymers or copolymers of VDF with other fluorine containing ethylenically unsaturated compounds, such as trifluorochloroethylene (CTFE), tetrafluoroethylene (TFE), HFP, vinyl fluoride (VF), hexafluoroisobutylene perfluoroacrylic acid, or with fluorine free ethylenically unsaturated compounds, such as cyclohexylvinyl ether, hydroxyethylvinyl ether, or a fluorine free diene compound, such as butadiene, isoprene and chloroprene. Preferred are VDF homopolymer, VDF/TFE copolymer and VDF/TFE/HFP copolymer.
A large number of acrylic type monomers and monomers copolymerizable with acrylic type monomers are taught for polymerization in the presence of the fluoropolymer seed. Included in the list of possible monomers are a number with functional groups capable of forming crosslinks with like groups in other polymeric molecules by reaction with groups they are capable of reacting with on other polymeric molecules or with monomeric crosslinking agents. No such materials were actually prepared. No differences in properties for these crosslinkable AMF molecules were suggested from the materials actually prepared, and there is no indication that selection of and inclusion of acrylic monomers containing crosslinkable functional groups in AMF preparation will provide AMF polymers having the superior applied use properties discovered by applicants.
Japanese Patent Application, publication number 4 [1992]-325509 discloses AMF polymers containing carboxyl functionality in the acrylic portion to provide improved aqueous dispersability in alkaline solutions. The fluoropolymer seed can be poly(vinylidene-fluoride) homo- or copolymers. None of the advantageous applied use properties found by the present inventors for crosslinked AMF polymers are suggested.
U.S. Pat. No. 5,646,201 teaches AMF polymers based on copolymers of vinylidene fluoride and chlorotrifluoroethylene for use in aqueous dispersion paints. A third comonomer may be present in the VDF based copolymer. CTFE must be present to obtain the gloss and flexibility claimed for the paint coatings. The acrylic phase may contain monomer residues bearing functional groups capable of crosslinking. No such AMF polymers were actually made, and the advantages found by the present applicants for crosslinked AMF compositions are not taught or suggested.
Japanese Published Patent Application HEI 8 [1996]-170045 discloses an aqueous coating material for inorganic building materials based on AMF polymers wherein the fluoropolymer seed may be based on a vinylidene fluoride-hexafluoropropylene copolymer and the acrylic phase may include monomers having functional groups capable of being crosslinked. No crosslinkable AMF polymers were actually made and the advantages found by the present inventors for crosslinked coatings were not suggested.
Japanese Published Patent Application HEI 8 [1996]-259773 is similar to this last reference, but requires the incorporation of monomers having cyclohexyl groups in the acrylic phase for a enhancement of adhesion of the coating films. Once again, no crosslinking of the acrylic phase is taught or suggested and there is no hint of the unique properties of the crosslinked films found by applicants.
Japanese Published Patent Application HEI 9 [1997] 165490 discloses crosslinked AMF based coatings wherein crosslinking is by reaction of polyfunctional hydrazines and reactive carbonyl groups in the acrylic phase. The disclosure clearly discloses that chlorotrifluoroethylene and vinylidene fluoride must be the predominant monomers in the fluoropolymer phase, and the only actual examples made are of that type of AMF polymer. The advantages found by applicants for their claimed compositions are not suggested.
International Patent Application WO 96/06887A1 discloses stable aqueous dispersions of vinylidene fluoride monomer and a reactive emulsifier and AMF polymers based on such vinylidene fluoride copolymers as seed.
The aqueous dispersions of both types of polymer are stated to be very stable. Crosslinking of coatings from either polymer type is not discussed and the properties found by applicants for such crosslinked coatings are not suggested.
SUMMARY OF THE INVENTION
The invention provides in a first composition aspect, an acrylic modified fluoropolymer based on a vinylidene fluoride polymer selected from the group vinylidene fluoride homopolymer and vinylidene fluoride-hexafluoropropylene copolymer wherein the acrylic portion of the polymer contains monomer residues having functional groups capable of entering into reactions whereby the acrylic portion becomes crosslinked with the proviso that the functional groups do not include solely carboxylic acid groups.
The tangible embodiments of the first composition aspect of the invention are white or light colored solids having physical and chemical characteristics tending to confirm the molecular structure assigned herein.
The aforementioned chemical and physical characteristics taken together with the method of synthesis and standard analytical technique measurements, such as dynamic mechanical analytical, infrared and nuclear magnetic resonance spectroscopic and differential scanning calorimetric measurements, further positively confirm the aforesaid structure for the first composition aspect of the invention.
The tangible embodiments of the first composition aspect of
Hedhli Lotfi
Wempe Larry
ATOFINA Chemicals, Inc.
Hu Henry S
Mitchell William D.
Wu David W.
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