Thermoplastic fluorocopolymers and the fluoromonomers used for t

Details Thermoplastic fluorocopolymers and the fluoromonomers used for t Thermoplastic fluorocopolymers and the fluoromonomers used for t

1994-05-12

1995-06-20

Schofer, Joseph L.

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

Synthetic resins

Polymers from only ethylenic monomers or processes of...

C08F21418, C08F21614

Patent

active

054261651

DESCRIPTION:

BRIEF SUMMARY
The present invention relates to fluoropolymers with improved temperature resistance and dimensional stability in the heat based on fluoroethylenes, for which perfluoro-(cycloalkyl-vinyl ethers) and optionally other monomers are used as comonomers. The present invention also relates to the perfluoro-(cycloalkyl-vinyl ethers) which impart the advantageous thermal properties to the fluoropolymers according to the invention.
Fluoropolymers are used in technology whenever special properties are required, such as low surface tension, high resistance to chemicals, oils or solvents or extreme resistance to (heat) ageing.
Polytetrafluoroethylene (PTFE), which is the most mass produced synthetic resin in the field of fluoropolymers, combines the above-mentioned properties to an eminent degree but, as is well known, cannot be processed thermoplastically. An improvement in the thermoplastic processibility is obtained by the introduction of comonomers which lower the viscosity of the polymer above the softening point (melting point in partially crystalline systems) and thus improve the melt flow. Hexafluoropropene and perfluorinated acyclic alkyl-vinyl ethers (U.S. Pat. No. 3,180,895) are examples of such comonomers but the introduction of such comonomers in most cases lowers the softening point of the copolymer so that the thermoplastic processibility is obtained at the expense of the temperature stability of the polymer.
Other fluorine-containing homopolymers, such as polyvinylidene fluoride or polychlorotrifluoroethylene, can be processed thermoplastically but owing to their low fluorine content they frequently do not reach the level in the above mentioned properties which is achieved by the most highly fluorinated (co)polymers.
It is an object of the present invention to provide new thermoplastically processible fluorocopolymers with increased resistance to temperature and dimensional stability in the heat based on fluorine-containing ethylenes as one of the comonomers.
It has been found that thermoplastic copolymers with increased temperature resistance and dimensional stability in the heat can be produced by the copolymerisation of fluorine-containing ethylenes with perfluoro-(cycloalkylvinyl ethers) corresponding to the following formula I. ##STR1## n=0, 1 or 2, m=3, 4 or 5.
Other comonomers may also be used for copolymerisation to modify the properties of the fluorocopolymers according to the invention. These other comonomers include in particular straight chain or branched C.sub.3 - to C.sub.8 -alkenes having at least one fluorine atom or fluorine-free ethylene or propylene.
The present invention thus relates to thermoplastic fluorocopolymers obtained by the copolymerisation of atoms and corresponding to formula I and ethylene, propylene and straight chain or branched C.sub.3 - to C.sub.8 -alkenes containing at least one fluorine atom.
The molar ratio of fluoroethylenes to perfluoro-(cycloalkyl-vinyl ethers) in the fluorocopolymers according to the invention is preferably from 1 to 50, most preferably from 2 to 20.
The ethylenes containing at least one fluorine atom (component a)) may be tetrafluoroethylene, trifluoroethylene, vinylidene fluoride, monofluoroethylene or chlorotrifluoroethylene. Tetrafluoroethylene and vinylidene fluoride are preferred.
Among the perfluoro-(cycloalkyl-vinyl ethers) of formula I, those in which n=0 are preferred. Perfluoro-(cyclopentyl-vinyl ether), i.e. the compound according to formula I in which n=0 and m=4, is particularly preferred for the invention.
The perfluoro-(vinyl-cycloalkyl)-ethers according to the invention are prepared from 2-cycloalkoxy-propane carboxylic acid fluorides (obtainable according to U.S. Pat. No. 3,274,239). They may be obtained by conversion into their alkali metal salts followed by decarboxylation at 170.degree. to 250.degree. C., as described in U.S. Pat. No. 3,274,239. If this process is employed, however, considerable quantities of 1,1,1,2-tetrafluoro-ethylcycloalkyl ethers are formed as by-products which are difficult to remove and only with hig

REFERENCES:
patent: 3274239 (1966-09-01), Selman

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