Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Process of treating scrap or waste product containing solid...
Reexamination Certificate
1999-03-26
2001-01-16
Silbaugh, Jan H. (Department: 1732)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Process of treating scrap or waste product containing solid...
C525S344000, C525S345000, C525S383000, C525S387000, C525S938000, C528S489000, C554S138000, C562S513000, C562S523000, C562S541000, C570S152000, C570S218000
Reexamination Certificate
active
06174928
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a fluorinated oligomer having COOH groups at both end, a process for producing the same and a composition comprising the same together with epoxy resin, and more particularly to a fluorinated oligomer having COOH groups at both ends, obtained by decomposition of fluorine rubber crosslinking products, a process for producing the same and a composition comprising the same with epoxy resin.
2. Description of Related Art
Utilization of ordinary rubber wastes by regeneration has no positive cost merits, but utilization of vulcanized fluorine rubber wastes, typical of which are flashes generated during the rubber vulcanization-molding, is an important task from the viewpoint of cost reduction, because the high raw material cost of fluorine rubber.
So far, the cross-linked, vulcanized fluorine rubber has been regenerated by mechanically pulverizing flashes, waste pieces, etc. of the crosslinked, vulcanized fluorine rubber, followed by plasticing, or by further treatment with nitric acid, potassium permanganate or various amines [JP-A 59-217734 and 59-217735; U.S. Pat. No. 3,291,761; DP-A 2 360 927 and 2 420 993; Kautschuk+Gummel·Kunststoffe 23. Jahrgang, Heft March 1976, page 218 and ibid. 45. Jahrgang, Nr. September 1992, page 742; Proiz-vo Shin, Rezinotekhn; Asbestotekhn. Izdfii (Moskva) 1979,vol. 6, page 7]. The regenerated fluorine rubber is mixed with virgin rubber (fresh rubber) as a filler and is used as a kind of extender.
However, the crosslinking structure of the crosslinked, vulcanized fluorine rubber must be decomposed to obtain the regenerated fluorine rubber from the crosslinked, vulcanized fluorine rubber. Furthermore, the vinylidene fluoride structure of vinylidene fluoride copolymer usually used in the fluorine rubber is actually hard to decompose under basic conditions or the crosslinking structure based on polyhydroxy compound (polyol) is not so decomposed even with a strong acid such as nitric acid, etc. as to regenerate and isolate the rubber moiety.
Still furthermore, the crosslinked, vulcanized fluorine rubber contains a filler in almost all the cases, and it is desirable to obtain regenerated fluorine rubber completely freed from such a filler. It is pointed out that the above-mentioned regeneration procedure is not always applicable, depending on the crosslinking system used for the formation of crosslinked, vulcanized fluorine rubber, and thus is not generally applicable.
On the other hand, U.S. Pat. No. 3,291,761 discloses a process for reclaiming revulcanizable polymers by dehydrogenfluoride reaction an amine-vulcanized vinylidene fluoride-hexafluoropropene copolymer and subjecting the resulting double bonds to oxidative decomposition, using KMnO
4
. Antipollution countermeasures are indispensable to the process with respect to removal of heavy metal Mn.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an oligomer obtained by decomposition of fluorine rubber crosslinking products, the oligomer being soluble in solvents and thus easy to separate from fillers, etc. and effectively utilizable as a chain-elongating agent for epoxy resin, isocyanate resin, oxazoline resin, etc.
The object of the present invention can be attained by a fluorinated oligomer having COOH groups at both ends and a &rgr;
50°
value of about 100 to about 10,000. Such a fluorinated oligomer having COOH groups at both ends can be produced by swelling fluorine rubber crosslinking products in an organic solvent, followed by decomposition in the presence of a base and a peroxide.
DETAILED DESCRIPTION OF THE INVENTION
Fluorine rubber crosslinking products to be decomposed according to the present invention are wastes such as flushes, scraps, molding failures, etc. resulting from vulcanization molding using polyol, amine, peroxide, or the like. Fluorine rubber to be vulcanization-molded includes, for example, copolymers of vinylidene fluoride with other fluorine-containing olefin or olefin such as at least one of tetrafluoroethylene, hexafluoropropene, chlorotrifluoroethylene, pentafluoropropene, perfluoro(alkyl vinyl ether), propylene, etc., typically such vinylidene fluoride copolymers as vinylidene fluoride-hexafluoropropene copolymer, vinylidene fluoride-hexafluoro-propene-tetrafluoroethylene terpolymer, vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-perfluoro(methyl vinyl ether)-copolymer, vinylidene fluoride-tetrafluoroethylene-perfluoro(methyl vinyl ether) terpolymer, etc. Besides the above-mentioned copolymers, tetrafluoroethylene copolymers such as tetrafluoroethylene-propylene copolymer, tetrafluoro-ethylene-perfluoro(methyl vinyl ether) copolymer, tetrafluoroethylene-perfluoro(methyl vinyl ether)-ethylene terpolymer, etc. can be used. The copolymers can also include copolymers with Br- and/or I-containing compounds, or monomers having such a crosslinkable group as a nitrile group, a glycidyl group, a hydroxyalkyl group, a perfluorophenyl group, etc.
These fluorine rubber crosslinking products are dipped in an organic solvent for thorough swelling of the entirety over one day or more and then are subjected to decomposition treatment. Any organic solvent can be used for this purpose, so long as it can swell the fluorine rubber crosslinking products, and such a solvent includes, for examples, ketones, amides (i.e. dimethylformamide, dimethylacetamide, etc.), sulfur-containing compounds (i.e. dimethyl sulfoxide, sulfolane, etc.), alcohols, lower fatty acids, esters, halogen-containing compounds (i.e. trichlorotrifluoroethane, hexafluoroisopropanol, trifluoroethanol, trichloroacetic acid, etc.), or the like.
Decomposition treatment in such a swollen state is carried out in the presence of a base and a peroxide. The base includes, for example, hydroxides, carbonates or organic acid salts of alkali metals, tertiary amines, tertiary phosphines, etc. The peroxide includes, for example, H
2
O
2
, persulfates, peracetic acid, organic peroxides, organic hydroperoxides, etc. H
2
O
2
is most preferable from the economical viewpoint. Addition of the base and the peroxide can be carried out in the order of the peroxide to the base each all in one run or in divided portions.
For the swelling in an organic solvent, it is preferable to use a phase transfer catalyst, typically, a quaternary onium salt such as a quaternary ammonium salt or a quaternary phosphonium salt, particularly in case of pulverized fluorine rubber crosslinking products as dispersed in a latex state, thereby contributing to an increase in the rate of decomposition reaction.
A quaternary ammonium salt or a quaternary phosphonium salt represented by the following general formula can be used as a quaternary onium salt:
(R
1
R
2
R
3
R
4
N)
+
X
−
(R
1
R
2
R
3
R
4
P)
+
X
−
where R
1
to R
4
are each an alkyl group having 1 to 25 carbon atoms, an alkoxy group, an aryl group, an alkylaryl group, an aralkyl group or a polyoxyalkylene group, or two or three of which may form a heterocyclic structure together with N or P; and X
−
is an anion such as Cl
−
, Br
−
, I
−
, HSO
4
−
, H
2
PO
4
−
, RCOO
−
, ROSO
2
−
, RSO
−
, ROPO
2
H
−
, CO
3
−−
, etc.
Specifically, the quaternary onium salt includes, for example, quaternary ammonium salts such as tetraethylammonium bromide, tetrabutylammonium chloride, tetrabutylammonium bromide, tetrabutylammonium iodide, n-dodecyltrimethylammonium bromide, cetyldimethylbenzylammonium chloride, methylcetyldibenzylammonium bromide, cetyldimethylethylammonium bromide, octadecyltrimethyl ammonium bromide, cetylpyridinium chloride, cetylpyridinium bromide, cetylpyridinium iodide, cetylpyridinium sulfate, 1-benzylpyridinium chloride, 1-benzyl-3,5-dimethylpyridinium chloride, 1-benzyl-4-phenylpyridinium chloride, 1,4-dibenzylpyridinium chloride, 1-benzyl-4-(pyrrolidinyl)-pyridinium chloride, 1-benzyl-4-pyridinopyridinium chloride, tetraethylammonium acetate, trim
Blagodatova Olga Viktorinovna
Kokotin Igor Vladimirovich
Mizuide Fumiyo
Sokolov Sergey Vasilievich
Tatsu Haruyoshi
Baker & Daniels
Jones Kenneth M.
Nippon Mektron Limited
Silbaugh Jan H.
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