Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C43/00—Ethers; Compounds having groups, groups or groups
  • C07C43/02—Ethers
  • C07C43/03—Ethers having all ether-oxygen atoms bound to acyclic carbon atoms
  • C07C43/14—Unsaturated ethers
  • C07C43/17—Unsaturated ethers containing halogen
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F14/00—Homopolymers and copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen
  • C08F14/18—Monomers containing fluorine

Definitions

• This invention relates to certain ⁇ , ⁇ -dihydrofluorovinyl ethers, homopolymers and copolymers thereof.
• Elastomeric fluoropolymers exhibit excellent resistance to the effects of heat, weather, oil, solvents and chemicals.
• Such materials are commercially available and are most commonly copolymers of vinylidene fluoride (VF 2 ) with hexafluoropropylene (HFP) and, optionally, tetrafluoroethylene (TFE).
• fluoroelastomers include copolymers of TFE with a perfluoro(alkyl vinyl ether) such as perfluoro(methyl vinyl ether) (PMVE), copolymers of TFE with propylene (P) and, optionally VF 2 , and copolymers of ethylene (E) with TFE and PMVE.
• these fluoroelastomers also contain copolymerized units of a cure site monomer to facilitate vulcanization. While these copolymers have many desirable properties, including low compression set and excellent processability, their low temperature flexibility is not adequate for all end use applications.
• One particularly desirable improvement would be a reduction in glass transition temperature (T 9 ) with an accompanying extension of service temperature to lower temperatures. T 9 is often used as an indicator of low temperature flexibility because polymers having low glass transition temperatures maintain elastomeric properties at low temperatures.
• U.S. Patent No. 5,268,405 discloses fluoroelastomers blended with a perfluoropolyether in order to reduce the T 9 of the composition.
• the perfluoropolyethers tend to be fugitive.
• the T 9 reverts to that of compositions containing no perfluoropolyether.
• Polyethers having an n value of 0 to 2 are said to have very little effect on T 9 .
• the glass transition temperature decreases with increasing level of copolymerized perfluorovinylpolyether units and with increased values of n.
• Chlorofluorocarbons such as F-113 may be employed as a polymerization solvent.
• solvents have environmental problems due to their ozone depletion potential.
• incorporation or conversion of perfluorovinylpolyether units into the elastomer is less in a chlorofluorocarbon solvent than it would be in an emulsion polymerization process if the polyether could be sufficiently emulsified.
• the perfluorovinyl ether is pre- emulsified with a surfactant prior to copolymerization with the comonomers. However, it is difficult to manufacture the latter perfluorovinyl ether. Typically, direct fluorination or electrochemical fluorination must be employed. Also polymerization reaction kinetics are relatively slow due to the ether.
• the glass transition temperature of fluoroelastomers may be significantly reduced when more than 22 mole percent of a certain ⁇ , ⁇ -dihydrofluorovinyl ether is copolymerized into the fluoroelastomers.
• Homopolymers of the ⁇ , ⁇ - dihydrofluorovinyl ethers also have good low temperature properties. The ⁇ -hydrogen atoms on these ethers activate the C-C double bonds resulting in excellent polymerization activity.
• Another aspect of the invention is a fluoroelastomer copolymer comprising:
• A) more than 22 mole percent of copolymerized units of an ⁇ , ⁇ - dihydrofluorovinyl ether monomer having the general formula R f -[CH 2 ] n - OCF CF 2 , wherein n is 1 or 2, and R f is selected from the group consisting of a perfluoroalkyl group, a perfluoroalkoxy group, a fluoroalkyl group and a fluoroalkoxy group; and
• Another aspect of the invention is a process for the preparation of a fluoroelastomer comprising:
• R f group may also be selected from the group consisting of a perfluoroalkyl group (preferably containing at least 4 carbon atoms) and a fluoroalkyl group (preferably containing at least 4 carbon atoms).
• R f group may also be selected from the group consisting of a perfluoroalkyl group (preferably containing at least 4 carbon atoms) and a fluoroalkyl group (preferably containing at least 4 carbon atoms).
• Homopolymers of the invention may be made by either solution or emulsion polymerization of the corresponding ⁇ , ⁇ -dihydrofluorovinyl ether. Polymerization may be initiated by an inorganic peroxide such as ammonium persulfate or by an organic peroxide such as 4,4'-bis(t- butylcyclohexyl)peroxy dicarbonate.
• an inorganic peroxide such as ammonium persulfate
• organic peroxide such as 4,4'-bis(t- butylcyclohexyl)peroxy dicarbonate.
• the preferred method for manufacturing the fluoroelastomers of this invention is emulsion polymerization so that conversion is high and chlorofluorocarbon solvents are not necessary.
• the ⁇ , ⁇ - dihydrofluorovinyl ethers employed in the fluoroelastomers of this invention are not very soluble in water.
• the ⁇ , ⁇ -dihydrofluorovinyl ethers should be emulsified prior to introduction of gaseous monomers and initiator to the reactor.
• a mixture comprising i) an ⁇ , ⁇ -dihydrofluorovinyl ether; ii) a fluorosurfactant and iii) water is first emulsified.
• a mixer such as a Microfluidizer® High Shear Processor (available from Microfluidics, a division of MFIC Corp.) facilitates emulsion preparation. It is critical that this emulsified mixture not contain gaseous comonomer.
• the mixture may further contain other ingredients such as a cure site monomer, pH buffer (e.g. sodium phosphate dibasic heptahydrate), and a fluorinated solvent such as a fluorinated alcohol (e.g.
• the maximum droplet size of the ⁇ , ⁇ - dihydrofluorovinyl ether is preferably less than 1 micron.
• the resulting emulsified ⁇ , ⁇ -dihydrofluorovinyl ether is then copolymerized in a conventional emulsion polymerization process with at least one gaseous fluoromonomer to form a fluoroelastomer.
• Fluoroelastomer copolymers of this invention comprise more than 22 (preferably more than 25) mole percent copolymerized units of an ⁇ , ⁇ - dihydrofluorovinyl ether monomer as defined above; and copolymerized units of at least one other copolymerizable monomer. Mole percent is based on the total number of moles of copolymerized monomer units in the copolymer.
• TFE tetra
• copolymers of the invention may contain 0.1 to 7 mole percent copolymerized units of cure site monomers commonly employed in the fluoropolymer industry.
• cure site monomers include, but are not limited to bromine- and iodine-containing olefins such as bromotrifluoroethylene, iodotrifluoroethylene, 4-bromo-3, 3,4,4- tetrafluorobutene, and 4-iodo-3,3,4,4-tetrafluorobutene.
• Such cure site monomers are well known in the art (e.g. U.S. Patent Nos. 4,214,060; 5,214,106; and 5,717,036).
• cure site monomers include 2- hydropentafluoropropene, 1-hydropentafluoropropene; 3,3,3- trifluoropropene; and nitrile group-containing fluoroolefins or fluorovinyl ethers such as those disclosed in U.S. Patent No. 6,211 ,319 B1 (e.g. perfluoro(8-cyano-5-methyl-3,6-dioxa-1-octene)).
• Fluoroelastomer copolymers of this invention may be prepared by known emulsion, suspension or solution polymerization processes.
• a chain transfer agent such as a perfluoroalkyldiiodide (e.g. 1-(CF 2 M), alcohols, ketones or hydrocarbons may be employed to control the polymerization.
• fluoroelastomers of this invention include, but are not limited to elastomers comprising copolymerized units selected from the group consisting of a) 25-76% VF 2 /10-50% HFP/ 26-65% DHFVE, b) 25-64% VF 2 /5-46% HFP/5-30% TFE/26-65% DHFVE, c) 25- 64% VF 2 /10-49% PMVE/26-65% DHFVE, d) 25-64% VF 2 /5-44% PMVE/5- 30% TFE/26-65% DHFVE, e) 5-30% VF 2 /20-40% TFE/10-40% P/26-65% DHFVE; f) 20-40% TFE/15-40% P/26-65% DHFVE; g) 10-30% E/15-40% TFE/10-20% PMVE/26-65% DHFVE and h) 15-44% TFE/20-45% PMVE/26-65% DHFVE.
• fluoroelastomers a) - h) are mole percentages based on the total moles of copolymerized comonomer units.
• DHFVE stands for an ⁇ , ⁇ -dihydrofluorovinyl ether.
• elastomers may further comprise at least one type of cure site as described above.
• ⁇ , ⁇ -Dihydrofluorovinyl ethers of the present invention are useful as monomers for the preparation of fluoropolymers.
• Homopolymers of ⁇ , ⁇ -dihydrofluorovinyl ethers are useful as coating materials.
• Copolymers of the present invention are useful in production of gaskets, tubing, seals and other molded components.
• Such articles are generally produced by compression molding a compounded formulation of the elastomer, a curing agent and various additives, curing the molded article, and then subjecting it to a post cure cycle.
• the cured parts have excellent low temperature flexibility and processability as well as excellent thermal stability and chemical resistance. They are particularly useful in applications such as seals and gaskets requiring a good combination of oil resistance, fuel resistance and low temperature flexibility, for example in fuel injection systems, fuel line connector systems and in other seals for high and low temperature automotive uses.
• the invention is now illustrated by certain embodiments wherein all parts and percentages are by weight unless otherwise specified.
• TFE tetrafluoroethylene
• the tube was then sealed and agitated at 50 0 C for 24 hrs.
• the TFE pressure was maintained at 400 psig (2.76 MPa) during the reaction process.
• the product was filtered to remove any solid residue, and dumped into water. The organic layer was separated and washed with fresh water. After removing the ether solvent in vacuo, the material was distilled to give the product as a clear, colorless liquid. Boiling point: 58°C at 80 mmHg. Three runs and a combined distillation gave about 195 g of product.
• cool-evacuated is meant that oxygen was removed from the reactor by cooling reactor contents sufficiently so that all ingredients remained in the reactor while a vacuum was applied to remove oxygen.
• the polymerization was run at 70 0 C for 8 hrs.
• the resulting polymer latex was coagulated with saturated magnesium sulfate solution.
• the precipitated polymer was collected by filtration.
• the polymer was washed thoroughly with warm water, and then dried in a vacuum at 80 0 C. 26.2 grams of white polymer was obtained. It had a T 9 of 16.5°C as measured by DSC (Differential Scanning Calorimetry).
• the polymer precipitated was collected by filtration.
• the polymer was washed thoroughly with warm water, and then dried in a vacuum over at 80 °C; 36.1 grams of white polymer was obtained.
• This polymer had a Tg at 2.7 °C as measured by DSC.
• Example 6 A polymer of the invention was prepared by a semi-batch emulsion polymerization process, carried out at 6O 0 C in a well-stirred reaction vessel.
• the emulsion was prepared by passing the ingredients through a Microfluidizer® twice at about 103 MPa.
• the reactor was heated to 60 0 C and then pressurized to 1.0 MPa with a monomer mixture of 60 wt.% vinylidene fluoride (VF 2 ) and 30 wt.% perfluoro(methyl vinyl ether) (PMVE).
• VF 2 vinylidene fluoride
• PMVE perfluoro(methyl vinyl ether)
• a 54.7 ml sample of a 0.001 wt.% ammonium persulfate initiator and 0.005 wt.% sodium phosphate dibasic heptahydrate aqueous solution was then added.
• VF 2 and PMVE were supplied to the reactor to maintain a pressure of 1.0 MPa throughout the polymerization.
• the initiator solution was fed continuously at 1.0 ml/hour through the end of the reaction period.
• a polymer of the invention was prepared by a semi-batch emulsion polymerization process, carried out at 60 0 C in a well-stirred reaction vessel.
• the emulsion was prepared by passing the ingredients through a Microfluidizer® twice at about 103 MPa.
• the reactor was heated to 60 0 C and then pressurized to 1.0 MPa with tetrafluoroethylene (TFE).
• TFE tetrafluoroethylene
• the resulting fluoroelastomer latex was coagulated by addition of an aqueous aluminum sulfate solution and the filtered fluoroelastomer was washed with deionized water.
• the polymer crumb was died for two days at 60 0 C.
• Example 8 A polymer was prepared by a semi-batch emulsion polymerization process, carried out at 60 0 C in a well-stirred reaction vessel.
• the emulsion was prepared by passing the ingredients through a Microfluidizer® twice at about 103 MPa. The reactor was heated to 60 0 C and then pressurized to 1.0 MPa with TFE.
• the resulting fluoroelastomer latex was coagulated by addition of an aqueous aluminum sulfate solution and the filtered fluoroelastomer was washed with deionized water.
• the polymer crumb was dried for two days at 60 0 C.
• a polymer was prepared by a semi-batch emulsion polymerization process, carried out at 60 0 C in a well-stirred reaction vessel.
• the emulsion was prepared by passing the ingredients through a Microfluidizer® twice at about 103 MPa. The reactor was heated to 60°C and then pressurized to 1.0 MPa with TFE.
• the resulting fluoroelastomer latex was coagulated by addition of an aqueous aluminum sulfate solution and the filtered fluoroelastomer was washed with deionized water.
• the polymer crumb was dried for two days at 6O 0 C.

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• 2006
  • 2006-08-03 US US11/498,907 patent/US20070088143A1/en not_active Abandoned
  • 2006-10-19 WO PCT/US2006/040764 patent/WO2007047788A1/en not_active Ceased
  • 2006-10-19 EP EP06817138A patent/EP1940762A1/en not_active Withdrawn
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