JP2006514125A - Fluoroelastomer copolymers based on tetrafluoroethylene, chlorotrifluoroethylene, hexafluoropropylene and vinylidene fluoride - Google Patents

Abstract

Fluoropolymer suitable for preparing fluoroelastomers. Fluoropolymers generally include repeating units derived from the monomers tetrafluoroethylene, hexafluoropropylene, vinylidene fluoride, chlorotrifluoroethylene, and optionally tetrafluoroethylene, hexafluoropropylene, vinylidene fluoride and chlorotrifluoroethylene. 1 type or more of repeating units derived from other fluorinated monomers.

Description

  The present invention relates to repeating units derived from fluoropolymers suitable for preparing fluoroelastomers, particularly tetrafluoroethylene (TFE), hexafluoropropylene (HFP), vinylidene fluoride (VDF) and chlorotrifluoroethylene (CTFE). Containing fluoropolymer. The invention further relates to a curable fluoroelastomer composition based on a TFE / HFP / VDF / CTFE copolymer and a fuel management system comprising a fluoroelastomer obtained by curing the fluoroelastomer composition.

  Fluoroelastomers are fluoroelastomer precursors (“rubbers”) made from monomers containing one or more fluorine atoms, or copolymers of such monomers with other monomers, with the largest amount of fluoromonomer present in mass. ) Is an elastomer prepared by curing. A fluoroelastomer precursor is a fluoropolymer suitable for preparing a fluoroelastomer having the desired elastic properties. Typically, the fluoroelastomer precursor is an amorphous fluoropolymer, i.e., a fluoropolymer with little known melting point. Fluoroelastomers have been successfully used in many applications due to their ability to withstand high temperatures and aggressive chemicals as well as the ability to process fluoroelastomer rubbers using standard elastomer processing equipment. Fluoroelastomers have also been used in fuel management systems such as automotive fuel hoses, filler hose, injector O-rings and the like. Fuel management applications require low fuel vapor permeability combined with good low temperature properties, sealability, and bending properties.

  A fluoroelastomer having a high fluorine content has good fuel permeation resistance. However, high fluorine content fluoroelastomers such as high fluorine content terpolymers based on tetrafluoroethylene, vinylidene fluoride, and hexafluoropropylene have several limitations. For example, high tetrafluoroethylene content (and hence fluorine content) tends to impair flexibility and processability. Regarding processability, the fluoroelastomer's stiffness is sufficient for curing and incorporation in standard processing equipment such as roll mills or Banbury mixers where the high fluorine content requires the material to have a melting point of less than about 100 ° C. May be too high. On the other hand, if the hexafluoropropylene content is too high at the expense of vinylidene fluoride, the polymerization rate can be unacceptably slow for commercial products.

  In order to overcome some of the limitations associated with using TFE / HFP / VDF copolymers (also known as THV copolymers), US Pat. is doing.

  (Patent Document 2) also discloses a THV copolymer for producing a fluoroelastomer. In particular, this patent describes a ternary displacement function for producing fluoroelastomers particularly suitable for use in wire coatings where good insulation properties, moldability, heat resistance, flame retardancy and flexibility are desired. Specific proportions of the monomers are taught. Patent Document 2 is not particularly concerned with providing a fluoroelastomer having superior properties for use in a fuel management system.

US Pat. No. 6,310,141 US Pat. No. 4,696,989 US Pat. No. 2,567,011 US Pat. No. 2,732,398 US Pat. No. 2,809,990 EP219065 specification International Patent No. 96/24622 Pamphlet Pamphlet of International Patent No. 97/17381 U.S. Pat. No. 4,745,165 U.S. Pat. No. 4,831,085 U.S. Pat. No. 4,214,060 US Pat. No. 4,501,869 US Patent No. 4,000,356 US Pat. No. 5,677,389 US Pat. No. 5,565,512 US Pat. No. 5,668,221 International Publication No. 00/09603 Pamphlet European Patent Application No. 0 661 304A1 European Patent Application Publication No. 0 784 064 A1 European Patent Application No. 0 769 521 A1 US Pat. No. 4,233,421 US Pat. No. 4,912,171 US Pat. No. 5,086,123 US Pat. No. 5,262,490 US Pat. No. 5,929,169 US Pat. No. 5,591,804 US Pat. No. 3,876,654 EP761735 specification Encyclopedia of Polymer Science and Engineering, 2nd edition, Volume 15, Silicone 204-308 (John Wiley & Sons), 1989 J.Am.Chem.Soc. 116 (1994) 4521-4522

  Despite the many known fluoroelastomers, particularly THV fluoroelastomers, it remains desirable to find other THV-based fluoroelastomer compositions that have superior properties for use in fuel management systems. In particular, it is desirable to find a THV-based fluoroelastomer that can be conveniently and cost-effectively manufactured, has good processing properties, good flexibility, and has properties that are particularly suitable for use in fuel management systems. ing. Thus, it will typically be desirable for the THV fluoroelastomer to have low gas and fuel vapor permeability.

3. SUMMARY OF THE INVENTION The present invention provides fluoropolymers that are suitable for preparing fluoroelastomers. This fluoropolymer is
a. 10 to 50 mol% of repeating units derived from tetrafluoroethylene,
b. 15 to 40 mol% of repeating units derived from hexafluoropropylene,
c. 25 to 59 mol% of repeating units derived from vinylidene fluoride;
d. 1 to 20 mol% of repeating units derived from chlorotrifluoroethylene,
Optionally
e. Repeating units derived from one or more fluorinated monomers other than tetrafluoroethylene, hexafluoropropylene, vinylidene fluoride and chlorotrifluoroethylene;
including.
The total amount of repeating units a to e is typically 100% in total.

  It has been found that the fluoropolymers identified above can be produced at high polymerization rates, particularly at rates higher than those corresponding to THV copolymers that do not contain CTFE-derived units. In addition, by including units derived from CTFE, a fluoropolymer having a high fluorine content can be prepared while maintaining high flexibility and good sealing properties when cured into a fluoroelastomer. Furthermore, the fluoroelastomers prepared therefrom are particularly suitable for use in fuel management systems because of their excellent gas and vapor permeability. The latter term can be used when handling fuel and means any system or system component including, for example, a fuel hose, fuel tank, filler hose, liner, and the like.

  Furthermore, when CTFE is present in the copolymer, bonding occurs in the presence of an organic compound having one or more hydride functional groups MH (wherein M is selected from the group consisting of Si, Ge, Sn, and Pb). It has also been found that the properties of the fluoropolymer bond to other base layers, including elastomer layers such as silicone rubber, when improved. The organic compound can be present in the fluoropolymer composition that prepares the fluoroelastomer or can be present in the base layer. Improving the bonding characteristics is of particular interest in fuel management systems where it may be necessary to bond the fluoroelastomer to other non-fluorinated components of the fuel management system.

  In another aspect, the present invention provides a curable fluoroelastomer composition comprising a fluoropolymer as defined above and a cured composition.

  In yet another aspect, the present invention provides a fuel management system comprising a fluoroelastomer obtained by curing a curable fluoroelastomer composition having a fluoropolymer and a cured composition. In addition to the coating, the fluoroelastomer of the fuel management system can include molded articles.

  In yet another aspect, the invention provides tetrafluoroethylene, hexafluoropropylene, vinylidene fluoride, chlorotrifluoroethylene and optionally further fluorine in an amount suitable to obtain a fluoropolymer having the composition as described above. A method for producing a fluoropolymer is provided, comprising the step of aqueous emulsion polymerization of the conjugated monomer.

4). DETAILED DESCRIPTION Fluoropolymers suitable for preparing fluoroelastomers contain TFE, HFP, VDF and CTFE repeat units in the amounts set forth in the present disclosure above. The preferred amount of repeating units derived from TFE is 15 to 45 mol%, the preferred amount of repeating units derived from HFP is 20 to 35 mol%, the preferred amount of repeating units derived from VDF is 28 to 58 mol%, and the repeating unit derived from CTFE The preferred amount is from 2 to 15 mol%. In addition to these units, the fluoropolymer may contain repeat units derived from other fluorinated monomers. A particularly preferred fluorinated comonomer for inclusion in the fluoropolymer is a fluorinated vinyl ether, particularly a perfluorinated vinyl ether. When present, the amount of repeating units derived from (per) fluorinated vinyl ethers can be up to 25 mol%, preferably up to 18 mol%, more preferably up to 15 mol%.

Examples of perfluorovinyl ethers that can be used in the present invention include the formula
CF ₂ = CF-OR _f
(Wherein R _f represents a perfluorinated aliphatic group that may contain one or more oxygen atoms) and the corresponding ones.

Particularly preferred perfluorinated vinyl ethers are of the formula
CF ₂ = CFO (R ^a _f O) _n (R ^b _f O) _m R ^c _f
Wherein R ^a _f and R ^b _f are 1-6 carbon atoms, in particular 2-6 carbon atoms, different linear or branched perfluoroalkylene groups, m and n are independently 0-10 And R ^c _f is a perfluoroalkyl group of 1 to 6 carbon atoms). Specific examples of perfluorinated vinyl ethers include perfluoro (methyl vinyl) ether (PMVE), perfluoro (ethyl vinyl) ether (PEVE), perfluoro (n-propyl vinyl) ether (PPVE-1), perfluoro- 2-propoxypropyl vinyl ether (PPVE-2), perfluoro-3-methoxy-n-propyl vinyl ether, perfluoro-2-methoxy-ethyl vinyl ether and CF _3- (CF ₂ ) ₂ -O-CF (CF ₃ )- CF ₂ —O—CF (CF ₃ ) —CF ₂ —O—CF═CF ₂ is included.

Perfluoroalkyl vinyl monomers suitable to the general formula CF ₂ = CF-R ^d _f or CH ₂ = CH-R ^d _f
Wherein R ^d _f represents a perfluoroalkyl group of 1 to 10, preferably 1 to 5 carbon atoms. A typical example of a perfluoroalkyl vinyl monomer is hexafluoropropylene.

  The fluoropolymer for preparing the fluoroelastomer has a bimodal or multimodal molecular weight distribution to improve the processing properties of the fluoropolymer. Generally, the weight average molecular weight of the fluoropolymer is between 10,000 and 500,000 g / mol.

  Fluoropolymers suitable for curing fluoroelastomers are typically prepared by free radical polymerization. Free radical polymerization is generally initiated by using a free radical generating initiator. As the initiator, any of known initiators often used for polymerization of fluorinated olefins such as tetrafluoroethylene can be used. For example, peroxide can be used as a free radical initiator. Specific examples of peroxide initiators include hydrogen peroxide, diacyl peroxide such as diacetyl peroxide, dipropionyl peroxide, dibutyryl peroxide, dibenzoyl peroxide, benzoylacetyl peroxide, diglutaric acid peroxide and peroxides. Dilauryl as well as water-soluble peracids and their water-soluble salts such as, for example, ammonium, sodium or potassium salts are included. Examples of peracids include peracetic acid. Similarly, esters of peracids can be used, examples of which include t-butyl peroxyacetate and t-butyl peroxypivalate. Another class of initiators that can be used are water-soluble azo compounds. Suitable redox systems for use as initiators include, for example, peroxodisulfates and bisulfite or bisulfite combinations, thiosulfate and peroxodisulfate combinations, peroxodisulfates and hydrazines or azodicarboxamides. (Including salts thereof, preferably including alkali or ammonium salts). Another initiator that may be used is an ammonium-alkali- or alkaline earth salt of manganic acid or manganic acid or manganic acid. The amount of initiator used is typically between 0.03 and 2% by weight, preferably between 0.05 and 1% by weight, based on the total weight of the polymerization mixture. The total amount of initiator can be added at the beginning of the polymerization, or the initiator can be added continuously to the polymerization mixture until 70-80% is converted during the polymerization. It is also possible to add part of the initiator at the start and the rest together or in separate additional parts during the polymerization. Preferred initiator systems include peroxodisulfate and permanganate.

  Free radical polymerization can also be performed in an organic solvent, and can also be aqueous suspension polymerization or aqueous emulsion polymerization. In the present invention, aqueous emulsion polymerization is preferred.

In aqueous emulsion polymerization, the fluorinated monomer is generally polymerized in the aqueous phase in the presence of a free radical initiator and a fluorinated surfactant or emulsifier, preferably a non-telogen emulsifier. The emulsifier will generally be used in an amount of less than 1% by weight, for example 0.1-1% by weight, based on the weight of the aqueous phase. Examples of fluorinated emulsifiers include linear or branched perfluoroalkyl salts containing carboxylic acids and sulfonic acids having 4 to 11 carbon atoms in the alkyl chain, in particular ammonium salts. Specific examples include perfluorooctanoic acid ammonium salt (APFO, described in US Pat. No. 6,057,049) C ₈ F ₁₇ SO ₃ Li (commercially available from Bayer AG), C ₄ F ₉ SO ₃ Li and C ₄ F ₉ SO ₃ K (described in (Patent Document 4)) is included. Another example of perfluoroalkyl containing a carboxylate is C ₈ F ₁₇ SO ₂ N (C ₂ H ₅ ) CH ₂ COOK (described in Patent Document 5). Still other emulsifiers that can be used include perfluoropolyethercarboxylate emulsifiers as described in US Pat. However, APFO is a preferred emulsifier because it can be easily removed from the polymerized product at the end of the polymerization. The aqueous emulsion polymerization can also be performed without adding a fluorinated emulsifier. Such polymerization is described in, for example, (Patent Document 7) and (Patent Document 8).

  As a preferred embodiment of the present invention for carrying out aqueous emulsion polymerization, an aerosol of liquid fluorinated monomer or liquid fluorinated, preferably perfluorinated hydrocarbon compound is provided, steam heated and fed into a polymerization vessel. An advantage of this embodiment is improved incorporation of CTFE into the fluoropolymer, which is particularly desirable when no fluorinated emulsifier or surfactant is added to the polymerization system. It will be appreciated by those skilled in the art that this finding is not particularly limited to the nature of the fluoropolymer and can therefore be used to improve the incorporation of CTFE into other fluoropolymers other than the subject of the present invention. Is understood. The term “liquid” means that the individual components are liquid at ambient temperature (20 ° C.) and atmospheric pressure (1 atm). Examples of liquid fluorinated monomers suitable for use in this embodiment are liquid (per) fluorinated vinyl ethers, such as those represented by the formulas set forth above. Suitable fluorinated hydrocarbons include those having 3 to 25 carbon atoms, including perfluorinated hydrocarbons and highly fluorinated hydrocarbons containing 1 or 2 hydrogen atoms or less. Examples of perfluorinated hydrocarbons include perfluorinated saturated linear, branched and / or cycloaliphatic compounds such as perfluorinated linear, branched or cyclic alkanes, perfluorinated benzene or perfluorinated Perfluorinated aromatic compounds such as tetradecahydrophenanthrene are included. It can also be perfluorinated alkylamines such as perfluorinated trialkylamines. Also, it can be a perfluorinated cycloaliphatic such as decalin, and preferably a heterocyclic aliphatic compound containing oxygen or sulfur in the ring such as perfluoro-2-butyltetrahydrofuran.

Specific examples of perfluorinated hydrocarbons include perfluoro-2-butyltetrahydrofuran, perfluorodecalin, perfluoromethyldecalin, perfluoromethylcyclohexane, perfluoro (1,3-dimethylcyclohexane), perfluorodimethyldecahydro. Naphthalene, perfluorofluorene, perfluoro (tetradecahydrophenanthrene), perfluorotetracosane, perfluorokerosene, octafluoronaphthalene, poly (chlorotrifluoroethylene), perfluoro (tripropylamine), perfluoro (tri Butylamine), or oligomers of perfluoro (trialkylamine) such as perfluoro (tripentylamine) and octafluorotoluene, hexafluorobenzene, and fluoriner Commercial fluorinations such as Fluorinert FC-75, FC-72, FC-84, FC-77, FC-40, FC-43, FC-70 or FC5312 (all from 3M Company) A solvent is included. Examples of useful highly fluorinated hydrocarbon compound C ₃ F ₇ - a _{[O-CF (CF 3)} -CF2] n -O-CHF-CF 3 ( wherein, n 1 to 10).

  Aqueous emulsion polymerization can be carried out continuously, but with continuous removal of the resulting emulsion or suspension, for example, monomers, water, optionally further emulsifiers, buffers and catalysts are used at the optimum pressure and temperature. Feed to reactor with stirring under conditions. An alternative technique is to feed the raw material into the reactor with stirring and react for a specific time at a set temperature, or put the raw material into the reactor and react the monomers until the desired amount of polymer is formed. Batch or semi-batch (semi-continuous) polymerization by feeding to a vessel to maintain a constant pressure. The polymerization can be carried out in standard or conventional tanks for the emulsion polymerization of gaseous fluorinated monomers.

  The polymerization system may contain buffers and, if necessary, auxiliaries such as complexing agents or chain transfer agents, such as alkanes such as ethane and n-pentane, dialkyl ethers such as dimethyl ether, Contains chlorine or bromine containing methyl t-butyl ether and chain transfer agent. The polymerization temperature may be 10-180 ° C, typically 30-100 ° C. The polymerization pressure can be 1 to 40 bar, typically 3 to 30 bar.

In a particular embodiment, the fluoropolymer can be prepared by initiating free radical polymerization in the presence of a chloride salt. In the presence of the chloride salt, a large number of polar, especially ionic end groups can be reduced, and CF ₂ Cl end groups are formed. This has been found to improve the processing properties of the fluoropolymer. In addition, CF ₂ Cl end groups can also improve the binding properties of fluoroelastomers to other base layers, especially when organic compounds with MH functional groups are present as described above.

  The curable fluoroelastomer composition according to the present invention comprises a fluoropolymer and a cured composition. Such a curable fluoroelastomer composition can be cured by any method known to those skilled in the art. The cured composition typically includes one or more components that form a three-dimensional network by linking fluoropolymer chains together. Such components can include catalysts, curing agents and / or crosslinking aids.

  In one embodiment for curing the fluoropolymer, a so-called peroxide curing system may be used. In a typical peroxide cure system, the fluoropolymer is provided with one or more cure sites that contain halogens that can participate in the peroxide cure reaction, and the composition for producing the fluoropolymer contains an organic peroxide. Oxides are included. The halogen that can participate in the peroxide cure reaction is typically bromine or iodine, which may be distributed along the polymer chain and / or included in the end groups of the fluoropolymer. Typically, the amount of bromine or iodine contained in the fluoropolymer is between 0.001 and 5% by weight, preferably between 0.01 and 2.5%, based on the total weight of the fluoropolymer. Furthermore, it has also been found that chlorine can also participate in the peroxide curing reaction of fluoropolymers in the presence of organic compounds having MH functional groups as described above. Thus, the fluoropolymers of the present invention containing chlorine atoms with units derived from CTFE can be used for curing in peroxide curing reactions. Of course, the fluoropolymer may additionally be modified with bromine and / or iodine.

In order to introduce a halogen that can participate in the peroxide curing reaction in addition to the chlorine atom of the CTFE unit along the chain, the copolymerization of the basic monomer of the fluoropolymer is carried out by using a suitable fluorinated curing site monomer (for example, (Patent Document) 9), (Patent Document 10), and (Patent Document 11)). Such comonomers are, for example, (a) bromo or iodo (per) fluoroalkyl-perfluorovinyl ethers having the following formula:
ZR _f -O-CF = CF ₂
(Wherein, Z is Br or I, R _f is optionally containing chlorine and / or ether oxygen atoms (per) fluoroalkylene C ₁ -C _12; for _{example, BrCF 2 -O-CF = CF} 2, BrCF 2 CF ₂ -O-CF = CF ₂ , BrCF ₂ CF ₂ CF ₂ -O-CF = CF ₂ , CF ₃ CFBrCF ₂ -O-CF = CF ₂ etc.);
(B) Bromo- or iodo (per) fluoroolefins having the following formula:
Z'-R ' _f -CF = CF ₂
Z'-R ' _f -CH = CH ₂
(Wherein Z ′ is Br or I, R ′ _f is a (per) fluoroalkylene C ₁ -C ₁₂ optionally containing a chlorine atom; for example, bromotrifluoroethylene, 4-bromo-perfluorobutene-1, etc. Or such as 1-bromo-2,2-difluoroethylene and 4-bromo-3,3,4,4-tetrafluorobutene-1 and 4-iodo-3,3,4,4-tetrafluorobutene-1 Bromofluoroolefin);
(C) may be selected from non-fluorinated bromo-olefins such as vinyl bromide and 4-bromo-1-butene.

Instead of or in addition to the cure site comonomer, the fluoropolymer is a cure site component derived from a suitable chain transfer agent introduced into the reaction medium during the preparation of a polymer derived from or suitable initiator described in US Pat. Can be included at the terminal positions. Examples of useful initiators include x (CF ₂ ) _n SO ₂ Na (where X is Br or I) or ammonium persulfate and potassium bromide and / or potassium iodide, with n = 1-10 An agent composition is included. The CF ₂ Cl end group chlorine introduced when the chloride salt is present at the beginning of the free radical polymerization can also participate in the peroxide curing reaction.

Examples of chain transfer agents include the formula R _f Br _x , where R _f is an x-valent (per) fluoroalkyl radical C ₁ -C ₁₂ optionally containing a chlorine atom, x is 1 or 2. What you have is included. Examples include CF ₂ Br ₂ , Br (CF ₂ ) ₂ Br, Br (CF ₂ ) ₄ Br, CF ₂ ClBr, CF ₃ CFBrCF ₂ Br, and the like. Other examples of suitable chain transfer agents include CH ₂ Br ₂ , CH ₂ I ₂ and those disclosed in (Patent Document 13).

  Suitable organic peroxides are those that generate free radicals at the curing temperature. Dialkyl peroxides or bis (dialkyl peroxides) that decompose at temperatures higher than 50 ° C. are particularly preferred. In many cases it is preferred to use a di-tert-butyl peroxide having a tertiary carbon atom with peroxy oxygen. The most useful peroxides of this type are 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-3 and 2,5-dimethyl-2,5-di (t-butylperoxy) Hexane is included. Other peroxides include dicumyl peroxide, dibenzoyl peroxide, t-butyl perbenzoate, α, α'-bis (t-butylperoxy-diisopropylbenzene), and di [1,3-dimethyl-3- (t It can be selected from compounds such as -butylperoxy) -butyl] carbonate. Generally, about 1-3 parts of peroxide are used for 100 parts of fluoropolymer.

Further, the curing site component may include a nitrile group-containing curing site monomer. Preferred useful nitrile group-containing cure site monomers include nitrile-containing fluorinated olefins and nitrile-containing fluorinated vinyl ethers as shown below.
CF ₂ = CF-CF ₂ -OR _f -CN
CF ₂ = CFO (CF ₂ ) _l CN
CF ₂ = CFO [CF ₂ CF (CF ₃ ) O] _g (CF ₂ ) _v O CF (CF ₃ ) CN
CF ₂ = CF [OCF ₂ CF (CF ₃ )] _k O (CF ₂ ) _u CN
(Referring to the formula above, where l = 2-12, g = 0-4, k = 1-2, v = 0-6; and u = 1-4, R _f is perfluoroalkylene or Valent perfluoroether group). Representative examples of such monomers include perfluoro (8-cyano-5-methyl-3,6-dioxa-1-octene), CF ₂ = CFO (CF ₂ ) ₅ CN, and CF ₂ = CFO (CF ₂ ) ₃ OCF (CF ₃ ) CN is included.

When the fluoropolymer includes a nitrile-containing cure site component, curing can occur using a catalyst that includes one or more ammonia-generating compounds. “Ammonia-generating compounds” include compounds that are solid or liquid at ambient conditions but generate ammonia under curing conditions. Such compounds include, for example, hexamethylenetetramine (urotropine), dicyandiamide, and the formula
A ^{w +} (NH ₃ ) _v Y ^w-
( ^Where A ^{w +} is a metal cation such as Cu ²⁺ , Co ²⁺ , Co ³⁺ , Cu ⁺ , Ni ²⁺ , w is equal to the valence of the metal cation, and Y ^w− is Counterion ions, typically halides, sulfates, nitrates, acetates, etc., where v is an integer from 1 to about 7).

（式中、Rは水素又は１〜約２０個の炭素原子を有する置換又は非置換アルキル、アリール、又はアラルキル基）のような置換及び非置換トリアジン誘導体もアンモニア生成化合物として有用である。特定の有用なトリアジン誘導体には、ヘキサヒドロ-1,3,5-s-トリアジン及びアセトアルデヒドアンモニア三量体が含まれる。 Also the formula

Substituted and unsubstituted triazine derivatives such as (wherein R is hydrogen or a substituted or unsubstituted alkyl, aryl, or aralkyl group having 1 to about 20 carbon atoms) are also useful as ammonia-generating compounds. Certain useful triazine derivatives include hexahydro-1,3,5-s-triazine and acetaldehyde ammonia trimer.

  Also, the fluoropolymer containing a nitrile-containing cure site component can be cured using one or more peroxide curing agents with an ammonia generating catalyst. Suitable peroxide curing agents for this purpose include those listed above. It will also be appreciated by those skilled in the art that the curable fluoroelastomer composition may include a mixture of cure site components, such as a mixture of nitrile-containing cure sites and a cure site containing a halogen that may participate in the peroxide cure reaction. I will. In the latter case, a mixture of ammonia-generating compound and peroxide will generally be used.

  In order to cure nitrile-containing fluoropolymers, aminophenols ((Patent Document 14)), ammonia salts ((Patent Document 15)), amidoxins ((Patent Document 16)) and other ammonia-generating compounds ((Patent Document 14) 17)) or all other known compounds such as imidoates can be used.

  Another component typically included in cured compositions based on organic peroxide and / or nitrile-containing cure site components is a crosslinking aid comprised of a polyunsaturated compound, which is useful in conjunction with the peroxide. Can be cured. These crosslinking aids can be added in amounts equal to 0.1 and 10 parts / 100 parts fluoropolymer, preferably 2-5 parts / 100 parts fluoropolymer. Examples of useful crosslinking aids include triallyl cyanurate; triallyl isocyanurate; triallyl trimellitate; tri (methylallyl) isocyanurate; tris (diallylamine) -s-triazine; triallyl phosphite; N, N -Diallylacrylamide; hexaallyl phosphoramide; N, N, N ', N'-tetraalkyltetraphthalamide; N, N, N', N'-tetraallylmalonamide; trivinyl isocyanurate; 6-trivinylmethyltrisiloxane; N, N′-m-phenylenebismaleimide; diallyl-phthalate and tri (5-norbornene-2-methylene) cyanurate. Triallyl isocyanurate is particularly useful. Other useful crosslinking aids include the bis-olefins disclosed in (Patent Document 18), (Patent Document 19) and (Patent Document 20).

  According to another embodiment, curing of the fluoropolymer can be accomplished using a polyhydroxy compound, and thus the cured composition will include the polyhydroxy compound. An advantage of using a polyhydroxy compound to cure the fluoropolymer is that it does not necessarily include a specific cure site component within the fluoropolymer. In addition to the polyhydroxy compound, the polyhydroxy cure system generally includes one or more organic onium accelerators in addition to the polyhydroxy compound. Organic onium compounds useful in the present invention typically contain at least one heteroatom, ie, a non-carbon atom such as N, P, S, O bonded to an organic or inorganic component, such as ammonium salts, phosphoniums Includes salts and iminium salts. One class of quaternary organic onium compounds useful in the present invention broadly includes phosphorus, arsenic, antimony or nitrogen generally constituting the central atom of the cation, and the anion is an organic or inorganic anion (eg, halogen). Relative cations and relative anions, which can be chlorides, sulfates, acetates, phosphates, phosphonates, hydroxides, alkoxides, phenol salts, bisphenol salts, and the like.

Many of the organic onium compounds useful in the present invention have been described and are known in the art. For example, (Patent Literature 21) (Worm), (Patent Literature 22) (Grootaert et al.), (Patent Literature 23) (Guenthner et al.), And (Patent Literature 24) (Kolb ) Et al., (Patent Document 25). All of these patents are incorporated herein by reference. Representative examples include the following individual listed compounds:
Triphenylbenzylphosphonium chloride tributylallylphosphonium chloride tributylbenzylammonium chloride tetrabutylammonium bromide triarylsulfonium chloride
8-benzyl-1,8-diazabicyclo [5,4,0] -7-undecenium chloride benzyltris (dimethylamino) phosphonium chloride benzyl (diethylamino) diphenylphosphonium chloride and mixtures thereof are included. Another class of useful organic onium compounds includes those having one or more pendant fluorinated alkyl groups. In general, the most useful fluorinated onium compounds are disclosed by Coggio et al.

  The polyhydroxy compounds can be used in free or non-salt form or as the anionic portion of selected organic onium promoters. The cross-linking agent functions as a cross-linking agent or co-curing agent for fluoropolymers such as the polyhydroxy compounds disclosed in US Pat. It can be any polyhydroxy compound known in the art. One of the most useful and commonly used aromatic polyphenols is 4,4′-hexafluoroisopropylidenyl bisphenol, commonly known as bisphenol AF. The compounds 4,4'-dihydroxydiphenyl sulfone (also known as bisphenol S) and 4,4'-isopropylidenyl bisphenol (also known as bisphenol A) are also widely used in practice.

  The cured composition based on the polyhydroxy compound may further comprise an acid acceptor. The acid acceptor can be inorganic or it can be a blend of inorganic and organic. Examples of inorganic receptors include magnesium oxide, lead oxide, calcium oxide, calcium hydroxide, dibasic lead phosphite, zinc oxide, barium carbonate, strontium hydroxide, calcium carbonate and the like. Organic receptors include epoxies, sodium stearate, and magnesium oxalate. Preferred acid acceptors are magnesium oxide and calcium hydroxide. The acid acceptors can be used alone or in combination and are preferably used in an amount ranging from about 2 to 25 parts by weight / 100 parts fluoropolymer.

  In another embodiment of the present invention, the curing composition may comprise an organic peroxide and a polyhydroxy based curing system as described above. Such cured compositions can be used with fluoropolymers having halogens that can participate in peroxide curing reactions as well as fluoropolymers without such halogens. When the fluoropolymer has a halogen capable of participating in a peroxide curing reaction, the curing composition having a polyhydroxy compound and a peroxide can perform so-called double curing. When an organic peroxide is used in the cured composition, the fluoropolymer has a fluoroelastomer layer bonded to another elastomer that is also formed using a peroxide cure system, such as in the case of silicone-based elastomers. It is particularly advantageous if it is to be formed.

  The curable fluoroelastomer composition may further include additives such as carbon black, stabilizers, plasticizers, lubricants, fillers, and processing aids typically used in the combination of fluoropolymers are intended. These can be incorporated into the compositions of the present invention if they have the stability suitable for the conditions of use.

  The curable fluoroelastomer composition can be prepared by mixing the fluoropolymer, the cured composition, and optionally organic compounds having hydride functional groups and other additives in a conventional rubber processing apparatus. Such devices include rubber rolls, closed mixers such as Banbury mixers, and mixing extruders.

As described above, the fluoropolymer has excellent bonding properties to other base layers, particularly when an organic compound having a hydride functional group MH is present. Moreover, a peroxide curable fluoropolymer composition can be obtained by including this compound in a fluoropolymer composition. Examples of this organic compound include siloxanes or silazenes having one or more MH functional groups. Typically, when the organic compound is a siloxane or silazane, the MH functional group will be a -SiH functional group. Preferably, the SiH functional group is -OSiH or NSiH so that hydrogen is attached to the silicon atom, which is further bonded to an oxygen or nitrogen atom. The siloxane or silazene can be a single low molecular weight organic compound, or it can be a polymeric compound comprising a polysiloxane that can be, for example, linear, branched, or cyclic. Specific examples include HSi (OCH ₂ CH ₃ ) ₃ , (CH ₃ ) ₂ (CH ₃ CH ₂ O) SiH, 1,1,3,3 tetraisopropyldisiloxane, obtained from United Chem Possible diphenyl-1,1,3,3-tetrakis (dimethylsiloxy) disiloxane, hydrogenated silyl-terminated poly (dimethylsiloxane), poly (methylhydrosiloxane) and copolymers of dimethylsiloxane and methylhydrosiloxane, 1, 3,5-trimethylcyclosiloxane and 1-phenyl-3,3,5,5-tetramethylcyclosiloxane are included. Polysiloxanes and siloxanes having SiH groups are known in the art and can be produced according to well-known procedures such as, for example, disclosed in: In addition, siloxanes having SiH groups are generally commercially available. Preferably, the molecular weight of the siloxane or polysiloxane will be between 150 g / mol and 10000 g / mol.

（式中、Rは任意に1つ以上の置換基を含む炭化水素基を表し、各R基は同じでも異なってもよく、これにより、2つのR基が互いに連結して環を形成することもでき、MはSi、Ge、Sn及びPbから選択され、qは1〜3の値であり、xは1〜3の値であり、y及びzは0〜3の値を表し、y+zの合計=4-xである）に対応する化合物とすることもできる。炭化水素基Rに存在することができる置換基の例としては、アルコキシ、アリールオキシ、塩素及び臭素のようなハロゲン、ニトリル基、ヒドロキシ基及びアミノ基が含まれる。炭化水素基の主鎖は、１つ以上の例えば酸素及び窒素原子のようなヘテロ原子によりさらに中断されることができる。炭化水素基の典型的な例としては、飽和又は不飽和の線状、分枝又は環状の脂肪族基及び芳香族基が含まれる。特定の例は、C₁-C₅アルキル基、炭素原子6〜12のアリール基、炭素原子7〜14のアリールアルキル及びアルキルアリール基である。上の式(I)の化合物は公知であり、例えば（非特許文献２）に記載されている。例としてはトリ(n-ブチル)スズヒドリド、トリ（エチル）シリルヒドリド、ジ（トリメチルシリル）シリルメチルヒドリド、トリ（トリメチルシリル）シリルヒドリド、トリ（フェニル）シリルヒドリドが含まれる。式(I)の化合物は、さらに、（特許文献２８）にも開示されている。 This organic compound also has the formula

(Wherein R represents a hydrocarbon group optionally containing one or more substituents, and each R group may be the same or different, whereby two R groups are linked together to form a ring) M is selected from Si, Ge, Sn and Pb, q is a value of 1-3, x is a value of 1-3, y and z represent a value of 0-3, y + The sum of z = 4-x). Examples of substituents that can be present in the hydrocarbon group R include halogens such as alkoxy, aryloxy, chlorine and bromine, nitrile groups, hydroxy groups and amino groups. The main chain of the hydrocarbon group can be further interrupted by one or more heteroatoms such as oxygen and nitrogen atoms. Typical examples of hydrocarbon groups include saturated or unsaturated linear, branched or cyclic aliphatic groups and aromatic groups. Specific examples are C ₁ -C ₅ alkyl groups, aryl groups of 6 to 12 carbon atoms, arylalkyl and alkylaryl groups of 7 to 14 carbon atoms. The compounds of the above formula (I) are known and described, for example, in (Non-patent Document 2). Examples include tri (n-butyl) tin hydride, tri (ethyl) silyl hydride, di (trimethylsilyl) silylmethyl hydride, tri (trimethylsilyl) silyl hydride, tri (phenyl) silyl hydride. The compound of the formula (I) is further disclosed in (Patent Document 28).

  The invention will be further described with reference to the following examples, but the invention is not limited thereto. All parts are by weight unless otherwise specified.

Test method:
Melt flow index (MFI) according to German Industrial Standard (DIN) 53735, International Organization for Standardization (ISO) 12086 or American Society for Testing and Materials (ASTM) D-1238 at a supporting weight of 5.0 kg, either at 265 ° C or 297 ° C. ) MFI was obtained using a standard extrusion die with a diameter of 2.1 mm and a length of 8.0 mm.

  The processability of the fluoropolymer was evaluated in a frequency sweep experiment using a strain controlled ARES flow meter from Rheometry Scientific. Viscosity data was determined at various shear rates in a 265 ° C. nitrogen atmosphere using a 25 mm parallel plate geometry and typically 10% strain.

  Unless otherwise specified, a 76 × 152 × 2 mm press-cured sheet for physical property testing was prepared by pressing at 5-7 MPa, 163 ° C. for 50 minutes. From these press-cured sheets, the tensile strength at break and the elongation at break were measured by ASTM D412. Hardness was determined by ASTM D2240 method A. A Shore A durometer was used.

  The melting peak of the fluororesin was determined by ASTM 4591 using a Perkin-Elmer DSC 7.0 at a heating rate of 10 ° C./min under nitrogen flow. The indicated melting point relates to the maximum melting peak.

  The molecular weight distribution was determined by size exclusion chromatography (SEC) and recorded in tetrahydrofuran-UV grade at 35 ° C. The SEC instrument consists of a Waters 510 isocratic pump, a Perkin Elmer ISS-100 autosampler, a Waters column oven, and a Polymer Laboratories three gel mixing bed type B column. (10 μm) (300 mm × 7.5 mm), and a Waters 410RI detector. The instrument was calibrated with 10 small polystyrene standard samples (PSS, Mainz / Germany) ranging from 1280 g / mol to 7,300,000 g / mol. SEC-elugrams calibrated with polystyrene were converted to molecular weight distributions with a universal calibration procedure using a Mark-Houwink coefficient α = 0.751 and K = 0.045396 ml / g.

  Latex particle size was determined by dynamic light scattering using a Malvern Zetazizer 1000 HSA according to ISO / DIS 13321. The reported average particle size is the Z average. Prior to measurement, the polymer latex obtained from the polymerization was diluted with a 0.001 mol / L KCl solution. In all cases the measurement temperature was 20 ° C.

In order to evaluate the vapor permeability (permeability) according to ASTM D814, a volume mixture of 42.5% toluene, 42.5% isooctane and 15% methanol was used as the test fluid. A 0.75-0.90 mm thick sheet of each polymer composition was press cured. A sample 3 inches in diameter was punched from each sheet. Vapor permeable cups with 2.5 inch openings (4.909 inch ² exposed sample surface) and a capacity of approximately 160 ml were used, which was developed by Thwing-Albert Instrument Co. ). High fluorine, low durometer fluoroelastomer gasket ensures a good seal between sample and test fluid. The cup was assembled by placing 100 ml of fluid and placing a 0.5 mm gasket between the cup and the sample and a 1.5 mm gasket between the sample and the clamp ring. Since the sample was extensible during the test, a 16 mesh circular screen was placed between the upper gasket and the clamp ring. All tests were conducted for 32 days at 40 ° C. with the cups upright. During the first 7 days of the test, no data collection was done to bring the sample to the permeable equilibrium. The cup was then weighed almost every other day. Next, each value was normalized by multiplying the transmittance by the thickness of the sample (millimeter).

Example 1 (Comparative test)
A total volume 186.1 l polymerization vessel equipped with an impeller stirrer system was filled with 114.6 l deionized water and 950 g of a 30 wt% aqueous solution of perfluorooctanoate ammonium salt (FX1006, APFO from 3M Company). In the next three cycles, the vessel was degassed and subsequently filled with nitrogen to ensure all oxygen was removed. The vessel was then heated to 71 ° C. and the agitation system was set to 210 rpm. The tank was filled with ethane to a reaction pressure of 0.6 bar absolute, HFP to 13.4 bar absolute, VDF to 14.1 bar absolute and TFE to 15.5 bar absolute. The polymerization was initiated with 983 g 30% APS solution (ammonium peroxosulfate). When the reaction starts, the feed rate HFP (kg) / TFE (kg) is 1.011, VDF (kg) / TFE (kg) is 0.528, and the reaction pressure is 15.5 absolute bar by supplying TFE, HFP and VDF to the gas phase. Maintained. The reaction temperature was also maintained at 71 ° C. After 4 hours and 25 minutes, the supply of 22 kg TFE was terminated, and the monomer valve was closed. The reactor was vented and N ₂ was flushed in 3 cycles.

  The 171 kg polymer dispersion thus obtained had a solid content of 32%. The latex particle diameter was 141 nm as measured by dynamic light scattering. The composition of the obtained fluoropolymer was 40 mol% TFE, 27 mol% HFP, 33 mol% VDF. The fluorine content of the fluoropolymer was 72.5% by weight.

1000 ml of this polymer dispersion was added dropwise to the aqueous MgCl ₂ solution with stirring to coagulate, then dehydrated and washed 3 times with deionized water (60-70 ° C.). The polymer was dried in a 130 ° C. air circulating oven overnight. The polymer starts to melt slightly at 67 ° C. and the heat of fusion is 0.7 J / g. The MFI (265/5) of the polymer is 105 g / 10 min.

Example 2
A polymer according to the present invention was prepared under the same conditions as the fluoropolymer of the comparative example of Example 1. The reaction tank of Example 1 was pressurized with ethane to an absolute pressure of 0.8 bar, CTFE to 1.2 bar, HFP to 11.2 bar, VDF to 13.1 bar, TFE to 15.5 bar. The polymerization was initiated with 983 g 30% APS solution. After the reaction starts rapidly, the reactor jacket is cooled to 71 ° C, the feed ratio CTFE (kg) / TFE (kg) is 0.209, HFP (kg) / TFE (kg) is 0.846, VDF The reaction pressure was maintained at 15.5 bar absolute by feeding TFE, CTFE, HFP and VDF into the gas phase with (kg) / TFE (kg) of 0.482. After 3 hours and 5 minutes, the supply of 21 kg TFE was terminated and the monomer valve was closed. The reactor was vented and N ₂ was flushed in 3 cycles.

  The solid content of the 169 kg polymer dispersion thus obtained was 31%. The latex particle diameter was 146 nm according to dynamic light scattering. The fluoropolymer had the following composition: 7.2 mol% CTFE, 22.6 mol% HFP, 30.2 mol% VDF and 40 mol% TFE. The fluorine content was 72.4% by weight and the total halogen content was 73.1% by weight. When polymer formation was carried out as in Example 1, the polymer started to melt slightly at 49 ° C. and the heat of fusion was 0.3 J / g. The MFI (265/5) of the polymer was 189 g / 10 min. The weight average molecular weight is Mw = 49,700 g / mol according to size exclusion chromatography, the molecular weight distribution appears to be symmetrical, and is polydisperse with Mw / Mn = 1.6.

  This example shows that HFP can be partially replaced with CTFE while maintaining a very low degree of crystallinity comparable to the fluoropolymer of Example 1. Moreover, the reaction rate increased by including CTFE.

Example 3
The fluoropolymer according to the present invention was prepared under the same conditions in the same reactor as in Example 1 and Example 2 except that APFOA was not used. The reaction pressure in the tank is 235g of PPV E-2 (supplied as steam heated aerosol) up to 0.62 absolute bar, 204g CTFE up to 1.17 absolute bar, 4760g HFP up to 10.87 absolute bar, 456g VDF up to 12.97 absolute Up to bar, 890g TFE was filled to 15.50 absolute bar. The polymerization was initiated by adding 980 g of 30% aqueous ammonium persulfate (APS) solution. When the reaction starts, the feed ratio CTFE (kg) / TFE (kg) is 0.209, HFP (kg) / TFE (kg) is 0.846 and VDF (kg) / TFE (kg) is 0.482, TFE, HFP, CTFE and VDF. Is maintained in the gas phase by maintaining the reaction pressure at 15.5 absolute bar. During the polymerization, PPVE-2 is additionally fed as a heated aerosol at a feed rate of 50 g / hour. The reaction temperature is also maintained at 71 ° C. After feeding 10.5 (kg) TFE, taking the liquid dispersion sample from the reactor and placing 85 g of ethane chain transfer agent into the vessel, the polymerization rate is substantially reduced. The polymerization is continued until 21.0 kg of TFE is fed after a total polymerization time of 4 hours and 35 minutes. After closing the monomer valve, the monomer gas phase reacts and within 15 minutes the tank pressure drops to 11.6 bar. Vent the reactor and flush with N ₂ for 3 cycles.

  The 168 kg polymer dispersion thus obtained had a solids content of 31%, and the subsequent polymer production was carried out in the same manner as in Example 1. The fluoropolymer had the following composition: 7.2 mol% CTFE, 39.9 mol% TFE, 30.2 mol% VDF, 22.6 mol% HFP and 0.1 mol% PPVE-2. The fluorine content was 72.2% by weight and the total halogen content was 73.1% by weight. The polymer starts to melt slightly at 88 ° C. and the heat of fusion is 0.8 J / g. The MFI (265/5) of the polymer is 188 g / 10 min. According to size exclusion chromatography, the mass average molecular weight is Mw = 50,500 g / mol, the molecular weight distribution appears asymmetric, has high molecular weight tailing, and is polydisperse with Mw / Mn = 3.1. Dispersion samples taken with 10.5 kg TFE feed were allowed to act under equivalent conditions. The MFI of this sample was 18.8 g / 10 min.

  This material was evaluated for processing behavior and compared to a single model of the material of Example 2. The processing evaluation data is summarized in Table 1.

Example 4
As described below, the polymers of Examples 1 to 3 were press cured using a bisphenol cured composition and various physical properties were measured. In each case, 100 parts of the polymer were mixed on a two roll mill with the following ingredients: (The following mmhr means mmol / 100 parts fluoropolymer by weight)
・ 5.94 (mmhr) bisphenol AF
・ The following phosphonium complexes of 0.54 (mmhr)
(C ₄ H ₉ ) ₃ P ⁺ CH ₂ CH (CH ₃ ) OCH ₃ ^- OC ₆ H ₄ C (CF ₃ ) ₂ C ₆ H ₄ OH
This is tributyl methoxypropyl phosphonium chloride prepared from tributyl phosphene (available from Cytec) allyl chloride and methanol and then reacted with the sodium salt of bisphenol AF.
-Another complex of 1.03 (mmhr). This is a complex prepared by reacting tributylmethoxypropylphosphonium chloride with the sodium salt of perfluorooctyl-n-methylsulfonamide.

  In addition, the following other ingredients were added. 3 g / 100 gram fluoropolymer magnesium oxide (Elastomag 170 obtained from Morton International) and 6 phr calcium hydroxide and 20 phr carbon black (N762). The composition was prepared in the form of individual sheets measured to 76 × 152 × 2 mm by compression at 5-7 MPa, 165 ° C. for 50 minutes. Finally, all three cured compounds were tested and various properties were compared according to the test procedure described above. The test results are shown in Table 2.

Claims (14)

A fluoropolymer suitable for preparing a fluoroelastomer, comprising:
a. 10 to 50 mol% of repeating units derived from tetrafluoroethylene,
b. 15 to 40 mol% of repeating units derived from hexafluoropropylene,
c. 25 to 59 mol% of repeating units derived from vinylidene fluoride;
d. 1 to 20 mol% of repeating units derived from chlorotrifluoroethylene, and optionally,
e. Repeating units derived from one or more fluorinated monomers other than tetrafluoroethylene, hexafluoropropylene, vinylidene fluoride and chlorotrifluoroethylene;
Said fluoropolymer.   The fluoropolymer of claim 1, wherein the optional one or more repeating units are derived from a perfluorinated vinyl ether monomer.   The fluoropolymer according to claim 2, wherein the optional one or more repeating units are present up to a total amount of 25 mol%.   The fluoropolymer of claim 1, wherein the molecular weight distribution of the fluoropolymer is bimodal or multimodal.   The fluoropolymer of claim 1, wherein the fluoropolymer comprises one or more cure sites that can participate in a peroxide cure reaction.   6. A fluoropolymer according to claim 5, wherein the cure site comprises bromine and / or iodine atoms.   A curable fluoroelastomer composition comprising the fluoropolymer according to any one of claims 1 to 6 and a cured composition.   The curable fluoroelastomer composition according to claim 7, wherein the curable composition comprises a polyhydroxy compound and an onium compound.   The curable fluoroelastomer composition according to claim 7 or 8, wherein the curable composition comprises an organic peroxide.   10. A curable fluoroelastomer composition according to any one of claims 7 to 9, further comprising an organic compound comprising a hydride functional group MH, wherein M is selected from Si, Ge, Sn and Pb. .   The component of a fuel management system containing the fluoroelastomer obtained by hardening the curable fluoroelastomer composition of any one of Claims 7-10.   Aqueous emulsion polymerization of tetrafluoroethylene, hexafluoropropylene, vinylidene fluoride, chlorotrifluoroethylene and optionally further fluorinated monomers in an amount suitable to obtain a fluoropolymer having the composition of claim 1. A process for producing the fluoropolymer according to claim 1.   13. The method of claim 12, wherein the method is performed without adding a fluorinated surfactant.   14. A method according to claim 12 or 13, wherein an aerosol of liquid fluorinated monomer or liquid fluorinated hydrocarbon is provided and sent to the reaction vessel by steam heating, where the aqueous emulsion polymerization is carried out.