Classifications

• • 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
  • C08F214/00—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
  • C08F214/18—Monomers containing fluorine
  • C08F214/22—Vinylidene fluoride
  • C08F214/222—Vinylidene fluoride with fluorinated vinyl ethers
• • 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
  • C08F14/22—Vinylidene fluoride
• • 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
  • C08F216/00—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 an alcohol, ether, aldehydo, ketonic, acetal or ketal radical
  • C08F216/12—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 an alcohol, ether, aldehydo, ketonic, acetal or ketal radical by an ether radical
  • C08F216/14—Monomers containing only one unsaturated aliphatic radical
  • C08F216/1408—Monomers containing halogen
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/13—Hollow or container type article [e.g., tube, vase, etc.]
  • Y10T428/1352—Polymer or resin containing [i.e., natural or synthetic]
  • Y10T428/139—Open-ended, self-supporting conduit, cylinder, or tube-type article

Definitions

• the present invention relates to the synthesis of new fluorinated elastomers having very low glass transition temperatures (T g ), good resistance to acids, petroleum and fuels, as well as good processing properties.
• the elastomers of the invention contain, by way of nonlimiting example, from 60 to 80 mol% of vinylidene fluoride (hereinafter "VDF”) and from 20 to 40 mol% of perfluoro (4-methyl- 3,6-dioxaoct-7-en) sulfonyl fluoride (hereinafter "PFS0 2 F").
• the present invention also relates to the preparation of these elastomers by radical copolymerization of the comonomers in the presence of different conventional organic initiators, such as peroxides, peresters, diazoic or allyl peroxypivalates.
• organic initiators such as peroxides, peresters, diazoic or allyl peroxypivalates.
• Fluorinated elastomers have a unique combination of extremely advantageous properties. Among these, mention may be made of their thermal resistance, to oxidation, to ultraviolet (UV) rays, to degradation due to aging, to corrosive chemical agents and to fuels. They also have low surface voltages, dielectric constants and refractive indices. They also resist absorption of water. All these properties make them materials of choice in various high-tech applications such as fuel cell components, seals in the aeronautical field, semiconductors in microelectronics, hoses, pipes, pump and diaphragm bodies in the chemical, automotive and petroleum industries. However, elastomers based on vinylidene fluoride (VDF or VF 2 ) are few.
• VDF or VF 2 vinylidene fluoride
• T g glass transition temperatures
• Viton ® B ie a T g of -26 ° C, which is surprising since the manufacturer announces a T g varying between -5 and -15 ° C for this product.
• the Ausimont company proposed a VDF / pentafluoropropene copolymer (Technoflon ® ) resistant to flames and oxidation, but having no T g below -26 ° C and whose comonomer is difficult to access.
• DuPont suggested a new generation of perfluoroalkyl vinyl ether (PAVE) elastomers resistant to low temperatures.
• copolymers have been produced, such as the copolymer of tetrafluoroethylene (TFE) / perfluoromethyl vinyl ether (PMVE) (Kalrez ®), the T g does not fall below -15 ° C, the TFE / PMVE described in EP 0 077 998, the T g of which are -9 ° C, or TFE / perfluoroalkylvinylether (PAVE) described in US 4,948,853. But it is especially the terpolymers which have even lower T g .
• the terpolymer TFE / ethylene / PMVE whose T g is -17 ° C, or the terpolymer TFE / VDF / PAVE (described in EP 0 131 308), and especially the terpolymer TFE / VDF / PMVE ( Viton GLT ® ) with a T g of -33 ° C.
• the T g increases with the percentage of TFE in the polymer, leading to poorer processing properties.
• Asahi Glass uses this same sulfonated monomer for the manufacture of Flemion ® membranes.
• F 2 C CFO [CF 2 CF (CF 3 ) 0] x C 2 F 4 C0 2 CH 3 (for Nafion ® or Aciplex ® membranes when x is 1 and for Flemion membranes ® if x is 0) are also used.
• VDF vinylidene fluoride
• the process leading to obtaining of the copolymer is however difficult to use and dangerous because of the very high pressures required.
• R F represents the group CF 2 CF (CF 3 ) OC 3 F 7 .
• the T g of the final product is -41 ° C.
• the object of the invention is therefore to develop new elastomers having a very low glass transition temperature (T g ) and obtained from inexpensive comonomers, for example VDF.
• Another subject of the invention is the preparation of these elastomers by a simple process which does not require dangerous experimental conditions.
• Another object of the invention is to know very precisely and without ambiguity the composition of the copolymers according to the invention, that is to say the molar percentages of each of the comonomers present in the copolymers.
• the present invention relates to elastomers comprising a comonomer of vinylidene fluoride (VDF) and a comonomer of perfluorosulfonyl ethoxy propyl vinyl ether (PSEPVE) or perfluoro (4-methyl-3,6-dioxaoct-7-ene) fluoride sulfonyl (PFS0 2 F) which elastomers containing neither tetrafluoroethylene (TFE), nor hexafluoropropene (HFP), nor of monomer carrying siloxane group and having very low glass transition temperatures (T g ) being between -32 and -36 ° C.
• VDF vinylidene fluoride
• PSEPVE perflu
• the VDF is in the majority in the composition of the elastomer.
• a molar percentage of 60 to 80% of VDF in the copolymer is particularly preferred.
• a sulfonated perfluoroalkoxy alkyl vinyl ether such as perfluoro (4-methyl-3,6-dioxaoct-7-ene) sulfonyl fluoride (PFS0 2 F) represents a preferred compound.
• the molar percentage of this second comonomer can vary between 20 and 40% in the copolymer.
• the invention also relates to a process for the preparation of these elastomers, characterized in that the preparation is carried out by radical copolymerization in the presence of an organic initiator at a temperature between 20 and 200 ° C, for a period of time between 2 and 10 hours, and at an initial pressure between 2 and 100 bars, and the said initial pressure is allowed to drop as the monomers are consumed.
• the fluorinated elastomers according to the invention can also comprise one or more fluorinated alkenes, the choice of which is left to a person skilled in the art.
• VDF was chosen for the preparation of the elastomers of the present invention, the latter being a cheaper alkene and easier to use than TFE. Being less expensive, it can therefore be used in greater quantity in the copolymer, which may comprise as second monomer a perfluoroalkoxyalkyl vinyl ether functional, for example with a carboxylate or a sulfonate.
• a perfluoroalkoxyalkyl vinyl ether functional, for example with a carboxylate or a sulfonate.
• Such functional perfluoroalkoxy alkyl vinyl ether are interesting because they favor crosslinking sites, in order to prepare original elastomers having good resistance to low temperatures and good processing properties.
• Terpolymers can also be envisaged, in which the third comonomer would preferably be a perfluoroalkyl vinyl ether (PAVE).
• the present invention describes the synthesis of original fluorinated elastomeric copolymers, based on vinylidene fluoride (VDF) and containing a functional perfluoroalkyl vinyl ether and / or a functional perfluoroalkoxyalkyl vinyl ether.
• VDF vinylidene fluoride
• Other fluorinated alkenes can optionally be added.
• poly (dimethyl siloxane) s have T g of -120 ° C as generally indicated in the following work: The Siloxane Bond: Physical Properties and Chemical Transformations, MG Voronkov, VP Mileshkevich, and Yu A. Yuzhelevskii, Consultants Bureau, New York (1978).
• the fluorinated elastomers of the present invention have very low T g which, for example, generally vary from -35 to -45 ° C, these elastomers thus being able to find applications in the field of plastics as an agent for implementation , or in other advanced industries such as aerospace, electronics or the automotive, petroleum, or transport of very cold fluids such as liquid nitrogen, liquid oxygen and liquid hydrogen.
• seals of high thermal resistance can be prepared from the present elastomers.
• these elastomers can be used for the manufacture of materials in the energy field, for example for the preparation of fuel cell components such as membranes.
• the fluorinated elastomers obtained by the present invention are predominantly made of VDF, therefore inexpensive.
• the scope of the present invention extends to all types of radical polymerization processes generally used: emulsion, miniemulsion, microemulsion, bulk, suspension, microsuspension and solution polymerization. All can be used according to their conventional implementation, but the solution polymerization was used preferentially for reasons of ease of implementation in the laboratory only, because in the case of solution polymerization, the operating pressures are low, or around 20 to 40 bars. In the case of emulsion, bulk and suspension polymerization, the operating pressure is higher, ie of the order of 40 to 100 bars.
• This therefore includes: vinyl fluoride (VF), trifluoroethylene, chlorotrifluoroethylene (CTFE), bromotrifluoroethylene, 1-hydropentafluoropropylene, hexafluoroisobutylene, 3,3,3-trifluoropropene, 1,2-dichlorodifluoroethylene, 2-chloro-1,1-difluoroethylene and generally all fluorinated or perfluorinated vinyl compounds.
• VF vinyl fluoride
• CTFE chlorotrifluoroethylene
• bromotrifluoroethylene 1-hydropentafluoropropylene
• hexafluoroisobutylene 3,3,3-trifluoropropene
• ethers perfluorovinyls can also play the role of comonomers.
• PAVE perfluoroalkyl vinyl ethers
• PMVE perfluoromethyl vinyl ether
• PEVE perfluoroethyl vinyl ether
• PPVE perfluoropropyl vinyl ether
• PAAVE perfluoroalkoxy alkyl vinyl ethers
• perfluoroalkoxyalkyl vinyl ethers with carboxylic ends or with sulfonyl fluoride ends such as perfluoro (4-methyl-3,6-dioxaoct-7-ene) sulfonyl fluoride, can also be used for the synthesis of fluorinated elastomers according to the present invention.
• Mixtures of PAVE and PAAVE may be present in the copolymers.
• fluorinated solvents of type C1CF 2 CFC1 2 , perfluoro-n-hexane (nC 6 F 14 ), n- C 4 F 10 , perfluoro-2-butyl-tetrahydro-furan (FC 75 TM); and - the usual solvents such as 1,2-dichloroethane, isopropanol, tert-butanol, acetonitrile and butyronitrile.
• the preferred solvents are methyl acetate, acetonitrile and perfluoro-n-hexane in variable amounts of between 30 and 60% by weight.
• the reaction temperature for the copolymerization is preferably between 20 and 200 ° C, more advantageously between 55 and 140 ° C.
• the pressure inside the polymerization autoclave preferably varies between 2 and 100 bars, advantageously between 10 and 100 bars, more precisely between 20 and 35 bars, depending on the experimental conditions.
• the polymerization can be initiated by conventional initiators of radical polymerization.
• initiators of radical polymerization include azo (such as AIBN), dialkyl peroxydicarbonates, acetylcyclohexanesulfonyl peroxide, dibenzoyl peroxide, alkyl peroxides, alkyl hydroperoxides, dicumyl peroxide, alkyl perbenzoates and alkyl peroxypivalates.
• dialkyl peroxydicarbonates such as diethyl and di-isopropyl peroxydicarbonates and to alkyl peroxypivalates such as t-butyl and t-amyl peroxypivalates and, more particularly, to peroxypivalates.
• alkyl as well as alkyl peroxides including t-butyl peroxide and 2,5-dimethyl-2,5-bis (t-butyl peroxy) hexane.
• the initial molar ratio between the initiator and the monomers is between 0.3 and 2%.
• a wide range of cosolvents can be envisaged, the solvents being present in various proportions in the mixture with water, for example from 30 to 70% by weight.
• anionic, cationic or nonionic surfactants can be used in amounts usually varying from 1 to 3% by weight.
• water is generally used as the reaction medium.
• fluorinated monomers are hardly soluble in water, hence the need to use surfactants.
• a cosolvent can be added to increase the solubility of fluorinated comonomers.
• acetonitrile, acetone or other alkyl alkyl ketones such as methyl ethyl ketone can, for example, be used.
• a microemulsion polymerization process as described in EP 0 250 767 or by dispersion, as taught in US 4,789,717; EP 0 196 904; EP 0 280 312 and EP 0 360 292 can be envisaged.
• Chain transfer agents can generally be used to reduce the molecular weights of the copolymers.
• R F is a perfluorinated group
• the elastomers of the present invention contain iodine and / or bromine atoms in the terminal position
• these elastomers could be crosslinked (or vulcanized) using peroxides.
• Well-known peroxide systems for example those described in EP 0 136 596, can fulfill this task.
• the vulcanization of elastomers can also be carried out by ionic methods conventional such as those described in US 3,876,654; US 4,259,463;
• % OlairedeNDF (I. I-83 + + 91 I -95 I-102 + + + I-108 I-110 I - ⁇ i3 + + I-116)
• I_j is the value of the integration of the signal located at -i ppm on the RM ⁇ spectrum of 19 F.
• table 1 highlights the head-tail and head-head sequences of the VDF unit blocks (at -91 and -113, -116 ppm respectively) as well as VDF / PFS0 2 F diades.
• copolymers of the present invention can find applications in the preparation of fuel cell components such as membranes, O-rings, pump bodies, diaphragms having very good resistance to fuels, gasoline, t-butyl methyl. ether, alcohols and engine oil, combined with good elastomeric properties, in particular very good resistance to low temperatures, given that the copolymers of the present invention have T g values varying from -30 to -40 ° C. These copolymers also have the advantage of being crosslinkable in the presence of agents conventionally used.
• VDF The monomer which is mainly used in the composition of fluorinated elastomers is VDF, which is much less expensive and much less dangerous than TFE.
• Example 1 VDF / PFS0 2 F copolymerization (initial molar percentages 71.1 / 28.9)
• a thick, borosilicate Carius tube (length of
• VDF vinylidene fluoride
• the respective quantities of gas (accuracy ⁇ 8 mg) introduced into the tube were determined by a relative pressure drop in this expansion tank, initially filled by a cylinder containing 300 g of VDF. Beforehand, the calibration curve "mass of VDF (in g) as a function of pressure drop (in bar)" was determined. For example, for 0.750 g of VDF, a pressure difference of 0.50 bar was required.
• the tube, under vacuum and still immersed in liquid nitrogen, is sealed with a torch and then placed in the cavity of an oven stirred at 75 ° C for 6 hours to complete the copolymerization.
• the tube is frozen again in liquid nitrogen then connected hermetically to a vacuum ramp, and open.
• the unreacted gases are then trapped in a previously tared metal trap and immersed in liquid nitrogen. 0.076 g of unreacted gas was trapped. This makes it possible to deduce the mass conversion rate of the VDF according to the expression:
• VDF represents the mass of VDF initially introduced.
• composition of the copolymer that is to say the molar percentages of the two comonomers in the copolymer, was determined by NMR of 19 F (200 or 250 MHz) at room temperature, acetone or DMF deuterated being the solvents reference.
• the 19 F NMR reference is CFC1 3 .
• the NMR experimental conditions were as follows: 30 ° of the "flip" angle, 0.7 s of acquisition time, 5 s of "dip” time, 128 "accumulation scans" and 5 ⁇ s width of "draws”.
• VDF / PFSO 2 F copolymerization (initial molar percentages 77.9 / 22.1)
• HC 276 TM Hastelloy
• a gas introduction valve equipped with a gas introduction valve, a release valve, a pressure gauge, a rupture disc in HC 276 and a magnetic stirring at 700 revolutions / min.
• 47.0 g (0.105 mol) of PFS0 2 F are introduced; 1.30 g (5.6 mmol) of 75% t-butyl peroxypivalate and 95.20 g of methyl acetate.
• the reactor is closed and its tightness is checked under 20 bars of nitrogen.
• the next cycle is carried out 3 times: the reactor is placed under vacuum, then nitrogen is introduced at 10-15 bars.
• VDF vinylidene fluoride
• C 0 [initiator] 0 / (INDFJ o + [PFSO 2 F] 0 ).
• the value of C 0 generally varies from 0.1 to 2%.

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• Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
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• 2000
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