CA2268072A1 - Liquid fluoric rubber - Google Patents
Liquid fluoric rubber Download PDFInfo
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- CA2268072A1 CA2268072A1 CA002268072A CA2268072A CA2268072A1 CA 2268072 A1 CA2268072 A1 CA 2268072A1 CA 002268072 A CA002268072 A CA 002268072A CA 2268072 A CA2268072 A CA 2268072A CA 2268072 A1 CA2268072 A1 CA 2268072A1
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- fluorinated rubber
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- 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
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Abstract
The invention concerns a novel liquid fluoric rubber, a process for its production, and its use.
Description
Le A 32 05l-Foreign CountriesBS/klu/S-P . . .
Liquid fluorinated rubber, a process for its manufacture and its use The invention relates to a new liquid fluorinated rubber, a process for its manufac-S tore and its use.
In the rubber industry there is a general desire for improved processability of the rubbers used. This relates in particular to the flow properties. The lower the vis-cosity of the crude rubber is, the simpler the processing technology, the greater the productivity and the less waste there is. These aspects are particularly important in the case of fluorinated rubbers because these are expensive rubbers which can-not be processed directly on injection moulding machines used in the rubber in-dustry.
Fluorinated rubbers with Mooney viscositiea (ML1+to at l20 ~C) > 60 can mostly only be processed by compression or transfer moulding methods. Although fluorinated rubbers with Mooney viscosities <_ 60 may be processed on special in-jection moulding machines for solid rubbers, this requires long cycle times and is also associated with a large amount of waste (flash-out), and small, complicated mouldings cannot be produced from them.
Rubbers with Mooney viscosities of 20-60 Mooney units which can be processed to produce compression mouldings according to this principle are known. These rubbers do not exhibit any distinct deterioration of the mechanical rubber proper-ties [P. Ferrandez, St. Bowers, Gummi Fasern Kunstst. 48 (l995) 626-633].
A further reduction of the molar weight for the purpose of reducing viscosity does, however, also lead to a deterioration in the vulcanizate properties (strength) of rubbers, particularly fluorinated rubbers. iJS-A 4 361 678, for example, describes liquid fluorinated rubbers which have a number average molecular weight between 900 and 10,000 g/mol and iodine contents between 1 and 30%. The products with iodine contents betlveen 4.5 and 26% described in the examples are already liquid at room temperature. Although they can be radically crosslinked via their terminal iodine atoms in the presence of peroxides and large quantities of co-crosslinking agents, the rubber properties of these elastomers are unsatisfactory.
Fluorinated rubbers in which the desired aim of low viscosity, which is required for processing according to liquid rubber injection moulding technology, is Le A 32 051-Foreign Countries - 2 - amended achieved via high iodine contents and hence low molecular weights, are known from prior application DE-P l96 221 88.9. Once again, however, low elongation values and/or strengths are the consequence.
Furthermore, these fluorinated rubbers can only be produced with a great deal of out-lay, since considerable problems and disadvantages arise during emulsion poly-merization because of secondary reactions of the molecular weight regulator in the aqueous phase and because of the formation. of water-soluble oligomers. Again, these lead to yield losses of the expensive molecular weight regulator, very long poly-merization times, high waste water load and poor product properties.
Practicable processes in non-aqueous media are not, however, known, since the solvents that are conventional for fluorinated. rubbers are very strong transfer agents for polymerization. In contrast, traditional fluorinated rubbers do not dissolve in inert solvents, such as chlorofluorocarbons, fluorocarbon or fluorinated hydrocarbon compounds. This leads to the rubber precipitating out as a compact, viscous mass during polymerization (precipitation polymerization) and, inter alia, forming wall deposits, the result of which is poor heat dissipation. This also causes problems on product discharge and low space/time yield because of greatly reduced monomer diffusion.
Liquid fluorinated rubbers which have a satisfactory property profile as regards both the viscosity relevant to processing and the; mechanical rubber properties of the end product are not known.
There was therefore a demand for liquid fluorinated rubbers which are pumpable at least at slightly elevated temperatures (60-120 ~C) and processable on traditional thermoplastics machines. These liquid fluorinated rubbers should also be readily crosslinkable and the resulting rubber components should have good mechanical and ageing properties which are very close to those of traditional solid fluorinated rubbers and should also be simple to produce.
It has now been found that a fluorinated rubber, consisting of vinylidene fluoride and optionally further monomer containing fluorine and/or not containing fluorine, and 0.5-2.5 wt.% of exclusively terminal iodine with a molecular weight Mn between 10,000 and 25,000 g/mol as well as a molecular non-uniformity of less than 1 and Le A 32 05l-Foreign Countries a complex viscosity at 100 ~C and w = 6... s 1 between 5 and l,000 Pas, has the desired property profile.
The invention therefore provides a liquid fluorinated rubber, consisting of vinyl-idene fluoride and optionally further monomers containing fluorine and/or not con-S taming fluorine as well as terminal iodine, characterized in that the iodine contents are 0.5-2.5 wt.%, the number average molecular weight (Mn) is between 10,000 and 25,000 g/mol and the molecular non-uniformity, defined as U = Mw/Mn-l, ~is less than 1 and the complex viscosity at l00 ~C and an angular frequency cu = 6.3 s 1 is between 5 and 1,000 Pa.s.
Monomers containing fluorine in the meaning of the invention are preferably fluorinated, optionally substituted ethylenes, which may contain hydrogen and/or chlorine as well as fluorine, such as vinylidene fluoride, tetrafluoroethylene and chlorotrifluoroethylene, fluorinated 1-alkenes with 2-8 carbon atoms, such as 1 S hexafluoropropene, 3,3,3-trifluoropropene, chloropentafluoropropene, hexafluoro-isobutene and/or perfluorinated vinyl ethers of the formula CF, = CF-O-X where X = Ct-C3-perfluoroalkyl or -(CF2-CFY-O)~-RF, wherein n = 1-4, Y = F or CFA
and RF = C1-C3-perfluoroalkyl.
Monomers not containing fluorine in the meaning of the invention are preferably ethylene, propene, isobutene or vinyl esters, such as vinyl acetate.
The combination of vinylidene fluoride, hexafluoropropene and optionally tetra-fluoroethylene and/or perfluorinated vinyl ethers, such as perfluoro-(methyl-vinyi-ether) is particularly preferred.
The liquid fluorinated rubbers according to the invention contain 0.5-2.5 wt.%
of iodine, which is covalently bonded to the terminal carbon atoms. This iodine is preferably introduced by molecular weight regulation with the aid of diiodo-organic compounds which act as chain-transfer agents.
Le A 32 051-Foreign Countries The number average molecular weight (Mn) of the liquid fluorinated rubber according to the invention is between 10,000 and 25,000 g/mol and was determined by membrane osmometry. The molecular non-uniformity, defined as U = Mw/Mn-l, is determined from gel permeation chromatography (GPC) measurements with RI detection in dimethylacetamide (DMAC) with the addition of 1 g/1 of Liar at 40 ~C, which were evaluated with a special calibration curve for polyethylene oxide. In the products according to the invention it lies at values < 1.
The complex viscosities of the liquid fluorinated rubber according to the invention, measured with a Bohlin rheometer of the VOR-Melt type (angular frequency cu _ 6.3 s ~) are between 5 and l,000 Pa.s at l00 ~C. They exhibit a very marked temperature dependence. The temperature index of the viscosities of the liquid fluorinated rubber according to the invention, calculated as quotient of the viscosities at 40 and 100 ~C, is preferably between I00 and 1,U00.
A further feature of the liquid fluorinated rubbers according to the invention is the fact that the complex viscosity increases preferably by the factor 5 maximum at temperatures >_ 80 ~C and reduction of the angular frequency from 50 to 0.5 s 1, i.e. virtually no structural viscosity can be observed.
The invention also provides a process for producing the liquid fluorinated rubber according to the invention, according to which vinylidene fluoride and optionally further monomers containing fluorine and/or not containing fluorine are radically polymerized in the presence of at least one diiodo-organic compound and at least one initiator in a liquid reaction phase in which the monomers, the initiator and the diiodo-organic compound are dissolved, at temperatures from 30 to 130 ~C
at a pressure in such a way that the content of the monomer in the liquid reaction phase is at least 20 wt.% and in the absence of water, wherein the fluorinated rubber formed forms a separate phase which is preferably liquid.
The diiodo-organic compounds used according to the invention for molecular weight regulation and/or as chain-transfer agents are preferably compounds of the Le A 32 05l-Foreign Countries type RI2 where R = an aliphatic hydrocarbon, fluorinated hydrocarbon, chlorofluo-rohydrocarbon or fluorocarbon group with 1-8 carbon atoms, wherein the two iodine atoms may be bonded to one or to different carbon atoms. Hydrocarbon or fluorocarbon compounds with one or four carbon atoms are particularly preferred, wherein the iodine is located at the terminal carbon atoms. Diiodomethane and/or 1,4-diiodoperfluorobutane are especially preferred. The quantity of diiodo-organic compound is preferably 0.5-2.8 parts by weight of iodine per 100 parts by weight of polymerized fluoromonomer.
Organic or fluoro-organic dialkyl peroxides, diacyl peroxides, dialkylperoxy di-carbonates, alkyl peresters and/or perketals are preferably used as initiator.
The type and quantity to be used depend on the particular reaction temperature.
The half lives of the peroxide to be selected preferably lie between 30 and 500 mins.
The quantities of initiator used are preferably between 0.1 and 1 part by weight, related to 100 parts by weight of monomers to be reacted.
I S In a preferred embodiment of the invention the polymerization is carried out in the presence of the initiator and the diiodo-organic compound and at least one inert solvent for the monomers. This reaction procedure, in which lower pressures and lower monomer use may be employed, has proved to be advantageous as regards the reaction procedure and the space/time yield. This type of polymerization is a 2-liquid phases polymerization, since the polymer arising (which is liquid under reaction conditions) is not soluble in the liquid monomer/solvent phase.
Surprisingly, the disadvantages which arise in traditional precipitation poly-merization may be avoided by this type of production.
The inert solvent used is preferably chosen in such a way that it undergoes no substantial transfer reactions under the reaction conditions. As such, certain fluorinated hydrocarbon, fluorinated chlorinated hydrocarbon or chlorofluorocarbon compounds are preferred, such as:
1,1,2,2,3,3-hexafluorocyclopentane, 1,1,2,2-tetralluorocyclobutane, 3 0 1-tri fluoromethyl-1,2,2-trifluorocyclobutane, 2,3-dihydrodecafluoropentane, perfluorobutylethane, Le A 32 05l-Foreign Countries 2,2-bis(trifluoromethyl)-1,3-dioxolane, perfluoro(tripropylamine), perfluoro(triethylamine), (methyl-2-hydrohexafluoropropyl)ether, 2-chloro-I,1,1-trifluoroethane, 1,2-dichlorotetrafluoroethane, I,1,2-trichlorotrifluoroethane and/or I,1,2,2-tetrachlorodifluoroethane.
The ratio of monomer to solvent and thf; degree of reactor filling is preferably selected in such a way that the content of the monomer in the liquid phase is at least 20 wt.% at reaction temperature. The quantity of monomer dissolved in the liquid phase may be determined, for example, from the mass balance with the aid of the partial pressures of the monomer present in the gaseous phase.
The reaction temperatures are preferably between 30 and 130 ~C. Lower tempera-tures lead to a drastic extension of the operating time and to a sharp rise in vis-I S cosity of the polymer, so that problems of mass transfer, heat dissipation and pro-duct discharge arise. The space/time yields cannot be increased substantially fur-ther with still higher temperatures, whereas the product properties deteriorate. A
particularly preferred temperature range for polymerization is 60-l20 ~C.
The pressure depends on the above-mentioned conditions and on the composition of the monomer mixture and is preferably between 10 and l50 bars. The process according to the invention is particularly preferably carried out at pressures be-tween 20 and 50 bars.
Polymerization may be carried out in the batch, continuous or batch/feed process in stirred-tank reactors, wherein the batchlfeed process is preferred.
In an embodiment of the invention, after polymerization has ended the fluorinated rubber is pressed out of the reaction vessel through a base outlet at a temperature which preferably corresponds at least to the reaction temperature. The temperature required for this step depends on the particular viscosity of the fluorinated rubber and should be increased with respect to the reaction temperature if the viscosity of the fluorinated rubber at reaction temperature does not yet permit an automatic outflow from the reactor.
Le A 32 OS 1-Foreign Countries In a further preferred embodiment of the invention, at least a part of the monomer and/or of the auxiliary solvent is still present to reduce the viscosity in the dis-charge process. The remaining monomer and/or auxiliary solvent is then separated from the product in a suitable unit and conveyed for re-use. The special ad-s vantage of this process compared with the conventional polymerization processes in aqueous dispersion, e.g. emulsion polymerization, lies in the fact that no further processing is required and, in particular, no waste water is generated.
The invention also provides the use of the liquid fluorinated rubber according to the invention as coating material or for producing rubber-elastic moulded bodies.
To produce a crosslinkable mixture as starting material for the production of rub-ber-elastic moulded bodies, fillers such as carbon black, silica, titanium dioxide, calcium silicate or barium sulphate, acid acceptors such as Ca(OH),, CaO, ZnO, MgO, and/or crosslinking chemicals, i.e. for example an organic peroxide in combination with a co-crosslinking agent such as triallyl isocyanurate (see EP-A
1 S 398 241 for example) or bisamines and/or bisphenols in combination with phase transfer catalysts and metal oxides, as described by A. L. Logothetis in Polym.
Sci. 14 (l989) 251-296, and further additives such as processing auxiliary sub stances, are added to the fluorinated rubber. These may be incorporated into the polymer both in known mixing units, such as kneaders and on two-roll mixers, and with the aid of mixers.
The improved flowability of the fluorinated rubber according to the invention permits the use of chemicals which crosslink and/or activate/trigger crosslinking, of increased reactivity, which cause speedier crosslinking. The fluorinated rubber according to the invention is preferably crosslinked radically by means of 2S conventional commercial peroxides in combination with triallyl isocyanurate, triallyl cyanurate, tri(meth)allyl isocyanurate, tetramethyltetravinylcyclotetra-siloxane, triallyl phosphite and/or N,N'-m-phenylenebismaleinimide.
l,l-bis(tert.butylperoxy)-3,3,5-trimethylcyclohexane, biscumyl peroxide, bis(1,1-di-methylpropyl)peroxide, n-butyl-4,4-di(tert.butylperoxy)valerate, 2,5-dimethyl-2,5-di-(tert.butylperoxy)hexane, 1,3-bis(2-tert.butylperoxy-isopropyl)benzene, tert.butyl-cumylperoxide, bis(tert.amyl)peroxide, bis(tert.-butyl)peroxide and/or tert.butylper-benzoate are preferably used as peroxides. The peroxides are preferably used in Le A 32 OS 1-Foreign Countries _g..
quantities of O.S-10 parts by weight, particularly preferably 1-4 parts by weight, related to l00 parts of fluorinated rubber.
Triallyl isocyanurate, triallyl cyanurate, tri(meth)allyl isocyanurate, tetramethyl-tetravinylcyclotetra-siloxane, triallyl phosphite and/or N,N'm-phenylbismaleinimide S are preferably used in quantities of O.S-12 parts by weight in each case, particularly preferably 1-6 parts by weight, related to l00 parts of fluorinated rubber.
Rubber-elastic moulded bodies may be produced both according to traditional methods conventional in the rubber industry, such as compression or transfer moulding, and on simple thermoplastic injection moulding or plunger-type metering machines. Preferably the fluorinated rubber according to the invention is introduced heated to 40 to 2S0 ~C into the thermoplastic injection moulding or plunger-type metering machine. Heated metering and conveying machines, prefer-ably heated piston pumps, are particularly suitable.
1 S Crosslinked mouldings with rubber-elastic and ageing properties which achieve the level of those made from solid fluorinated rubbers can be produced from the fluorinated rubbers according to the invention with the advantageous technology of liquid rubber processing.
The examples below serve to explain the invention without, however, having a limiting effect.
Le A 32 05l-Foreign Countries Examples:
Example 1 620 ml of 1,1,2-trichloro-2,2,l-trifluoroethane (Frigen 113, R 1l3) and 9 g of di-iodomethane (DIM, from Merck) were placed in a 4.1 I autoclave. The closed autoclave was evacuated twice accompanied by cooling, then 3 bars nitrogen pressure was applied and 10 minutes' slow stirring took place in each case.
440 g of vinylidene fluoride (VDF) and 880 g of hexafluoropropene (HFP) were placed into the evacuated autoclave and the reaction mixture was heated to 60 ~C
accompanied by stirring. When this temperature had been reached the autoclave internal pressure was 27 bars. From this, the content of dissolved monomer in the liquid phase was estimated at approx. 47 wt.%. Polymerization was initiated by the addition of 3.4 g of tert.-butylperoxypivalate as TBPPI-75-AL (solution in aliphatics, Messrs Peroxid-Chemie Gmb:Ei) with a peroxide content of 59%
dissolved in 20 g of Frigen 113. Polymerization commenced after a few minutes, as could be seen from the incipient pressure drop. During polymerization a mono-mer mixture of 60 wt.% of vinylidene fluoride and 40 wt.% of hexafluoropropene was further added under pressure in such a way that the autoclave internal pressure was constantly maintained at 27 + 0.4 bars. A total of 306 g of vinylidene fluoride and 200 g of hexafluoropropene was further metered in in this way in the course of a 12-hour reaction time. When polymerization was completed the reaction mixture was cooled and the unreacted monomer mixture re-moved from the reactor by decompression and evacuation. The remaining reactor contents (polymer + Frigen) were heated to 80 ~C accompanied by stirring. 15 minutes after the stirrer was switched off the reactor contents were completely dis-charged via a base discharge valve into a second pressure vessel underneath.
No product residues remained in the reactor.
After the product had been separated from the Frigen 113 (R 1l3) it was dried, wherein 488 g of a viscous copolymer resulted.
The following copolymer composition was determined by 19F-NMR analyses (solvent: acetone; standard: CFCl3): 20.7 mol% of hexafluoropropene, 79.3 mol%
of vinylidene fluoride.
Le A 32 05l-Foreign Countries The iodine content of the polymer, determined by elementary analysis, was 1.5 wt.%. The number average molecular weight (membrane osmosis) was l4,900 g/mol. The molecular non-uniformity U determined by GPC examinations was 0.79.
The complex viscosities were measured at different temperatures using a Bohlin rheometer of the VOR MELT type. The reaults are shown in Table 1.
To produce a crosslinkable mixture, 30 parts of carbon black MT N 900, 3 parts of calcium hydroxide, 4 parts of Perkalink 301/S0 (triallyl isocyanurate, 50%
on silica gel) and 3 parts of Luperco 130 XL,-45 (2,5-dimethyl-2,5-bis(tert.butyl-peroxy)-hexine-3; 45% in inactive fillers) were incorporated to l00 parts by weight of the fluorinated rubber copolymer on a well-cooled two-roll mixer.
To determine the crosslinking behaviour the mixtures containing peroxide were examined in a Monsanto rheometer of the MDR 2000 E type at 170 ~C (measure-ment time 30 mins).
The mixtures were pressure-vulcanized at 170 ~C and 200 bars in moulds for 1x10x10 mm plates and 6x70 mm cylinders for 30 minutes and then further vulcanized in a circulating air oven (1 hour at l60 ~C, 1 hour at 170 ~C, 2 hours at 180 ~C and 20 hours at 230 ~C). The tensile/elongation properties before and after hot air ageing (72 hours/275 ~C) and/or oil ageing (S x 94 hours in BP
MK
4437 at l60 ~C) and the compression sets (cylinder, 70 hoursl200 ~C) were deter mined on the vulcanized moulded bodies. The results are shown in Table 2.
Examples 2-5 Polymerization was carried out in a manner similar to Example 1, wherein the quantities of monomer and Frigen initially introduced were changed on the one hand and the temperature set at 40 and/or 80 ~C on the other hand, and dicyclo-hexylperoxydicarbonate (CHPC) and/or tert.-butyl-per-2-ethylhexanoate (TBPEH) were used as peroxides in the quantities below and the following results obtained:
Le A 32 05l-Foreign Countries -ll-Parameters 2 3 4 5 varied Example and results Polymerization 60 60 40 78 temperature [C]
R 113 [g] 480 980 980 980 QuantitiesVDF [g] 882 220 440 440 introduced:
HFP [g] 1760 440 880 880 DIM [g] 13 3 9 9 Reaction 37 20 20 32 pressure [bars]
Monomer 78 29 S0 45 content ' in the liquid [wt.~o]
phase Peroxide TBPPI TBPPI CHPC TBPEH
Peroxide 59 59 93 l00 content 3.5 2.67 7.4 2.5 [%]
Quantities used [g]
Time [h] 22.4 16 12.8 7 Product 600 330 483 470 yield [kg]
Iodine 1.4 0.7 1.4 1.5 content [wt.io]
Composition 80.7 78.6 80.5 79.2 VDF/I-IFP l9.3 2l.4 19.5 20.8 [Mol%]
[Mol%]
Mn [glmol] 14 400 21 1 2 13 400 U 0.86 0.93 0.87 0.64 The rubbers from Examples 3,4 and 5 were vulcanized in a similar manner to that described in Example 1, wherein 3 parts of Luperco 101 XL-45 (2,5-dimethyl-2,5-bis(tert.butylperoxy)-hexane; 45% in inactive fillers) were used as peroxide, however, instead of Luperco 130 XL-45. The results are shown in Table 2.
Le A 32 OS 1-Foreign Countries Table l: Complex viscosities rl* at different tempertures, measured with a VOR-Melt Bohlin rheometer (angular frequency c~ = 6,3 s'1), in Pas in each case and quotients of the values measured at 80~C at w = 0,5 and 50 s 1 Example 1 2 3 4 5 Comparative example( 1 2 40C 31500 2730023200 l12007860 12500l470 80C 370 360 R20 262 4l0, 420 115 100C 110 105 2 00 74 52.6 l60 2.2 l20C 33 30 E>7 32 34 81 1.0 140C 12 10 2 5 17.2 20.8 45 0.43 r~*(40C)/rl*(100C)286 260 l.16 151 149 78 668 rl*(80C;O.Ss I)/ 1.2 1.2 1.1 1.9 1.2 3.1 1.2 r~*(80C;SOs 1) Le A 32 05l-Foreign Countries Example 6 Polymerization was carried out in a manner similar to that of Example 1, wherein 15.2 g of diiodoperfluorobutane (DIFPB, Fluorochem Ltd) were used, after prior purification by shaking out with aqueous sodium thiosulphate solution, instead of the diiodomethane, and the following results were obtained:
Time [h] 11.2 'Product yield ......_..._..__[k~j_._.........'4~0 '.........._............
...........
Iodine content."...._.............._.........1...~............_..........._..
[~.%] _.....
~Composition:'..................................._._....._....................
................................_.
S VDF [Mol%] 79 HFP [Mol%] 21 ..~ .._.___.._........._...............................__.[~~ofj....... ..1.~
..000 ..........._.....
..U~__.._..................._.._..._.................._._..._.............._...
........ . Ø;
g.l ..........................
Example 7 Polymerization was carried out in a manner similar to Example 6, wherein 633 ml of perfluoro(tripropyl)amine were used instead of the Frigen 113 (R 113) and 11.9 g of DIPFB.
After a total operating time of 15 hours, 360 g of a polymer which had high vis cosity at room temperature and low viscosity above 70 ~C and an iodine content of 1.5% was isolated.
Le A 32 05l-Foreign Countries Comparative example 1 (Fluorinated rubber, produced by emulsion polymerization).
25.2 kg of deionized water and 60.2 g of lithium perfluoro-octylsulphonate were placed in a 36 1 autoclave. 40 g of oxalic acid dihydrate and 31 g of diiodo-methane (Merck) were dissolved therein, wherein a pH value of 3.2 established in the entire aqueous initial material presented. The closed autoclave was evacuated four times, then 3 bars nitrogen pressure ;vas applied and slow stirring took place for 10 minutes in each case. 269 g of vinylidene fluoride and 368 g of hex-afluoropropene were placed into the evacuated autoclave and the reaction mixture was heated to 25 ~C accompanied by stirring. When this,temperature had been reached the autoclave internal pressure was 9.4 bars. Polymerization was initiated by the addition of 53 ml of an aqueous solution which contained 20 g/l of potassium permanganate. Immediately after this one addition the said solution was continuously further metered at a rate of 39 ml/hr. Polymerization 1 S commenced after 26 minutes, as could be seen from the incipient pressure drop.
During polymerization a monomer mixture of 60 wt.% of vinylidene fluoride and 40 wt.% of hexafluoropropene was further added under pressure in such a way that the autoclave internal pressure was constantly maintained at 9.4 t 0.2 bars.
After Z00 g of monomer conversion in each case, 30 ml of a solution of diiodomethane in 1,1,2-trichloro-1,2,2-trifluoroethane (100 g/1) were also added.
A total of 944 g of vinylidene fluoride and 622 g of hexafluoropropene, and 45 g of diiodomethane, were pumped in in this way in the course of a 15-hour reaction time. To end polymerization, the permanganate metering was ceased, the unre-acted monomer mixture removed from the reactor by decompression and evacuation and the remaining autoclave <:ontents cooled down. 1340 g of a soft rubber-like copolymer was isolated from the latex by freeze-coagulation, washing and drying for 24 hours at 50 ~C in a vacuum drying cabinet.
The following copolymer composition was determined by 19F-NMR analyses:
19.8 mol% of hexafluoropropene, 80.2 mol% of vinylidene fluoride.
The iodine content of the polymer is 2.'7 wt.%. The number average molecular weight (membrane osmosis) is approx. 9,000 g/mol, the non-uniformity U is 1.2.
The complex viscosities measured on this product are also entered in Table I.
Le A 32 051-Foreign Countries From this it can be seen that this product has higher viscosities and greater dependence on the shear rate gradient at temperatures above 80 ~C despite the lower molecular weight.
The resulting rubber was vulcanized as described in Example 1. The results, which are also shown in Table 2, show that the vulcanized test bodies exhibit lower elongation values in both the initial state and after the ageing tests.
Comparative example 2 2.78 kg of deionized water and 4.5 g of lithium perfluoro-octylsulphonate were placed in a 4.1 1 autoclave. 40 g of 1.,4-diiodoperfluorobutane were dissolved therein. The closed autoclave was evacuated four times, then 3 bars nitrogen pressure was applied and 10 minutes' slow stirring took place in each case. 27 g of vinylidene fluoride and 53 g of hexafluoropropene were placed into the evacuated autoclave and the reaction mixW re was heated to 80 ~C accompanied by stirring. When this temperature had been reached the autoclave internal pressure was 15 bars. Polymerization was initiated by the addition of 2.8 g of ammonium peroxydisulphate dissolved in 20 g of water. Polymerization commenced after 7 minutes, as could be seen from the incipient pressure drop. During polymerization a monomer mixture of 60 wt.% of vinylidene fluoride and 40 wt.% of hexafluoro-propene was further added under pressure in such a way that the autoclave internal pressure was constantly maintained at 17 _~ 0.2 bars. A total of 93 g of vinylidene fluoride and 216 g of hexafluoropropene was further metered in in this way in the course of a 6-hour reaction time. To e:nd polymerization, the reactor contents were cooled down and the unreacted monomer mixture removed from the reactor by decompression and evacuation. The latex was coagulated by stirring into a 6%
calcium chloride solution, washed with water and dried in a vacuum drying cabinet for 24 hours at 50 ~C, wherein '280 g of a viscous copolymer were ob-tained.
Le A 32 OS 1-Foreign Countries Iodine content [wt.%] ~ 4.8 Composition:
VDF [Mol%] 8c).5 HFP [Mol%] 1'7.3 S -(CFZ)4- [Mol%] 2.2 ...M .....-..............................._.._.._-..__._.._.[~mol~...__ ..5Z00 I U I 1.0 The product was initially vulcanized in a similar manner to the products from Ex-amples 3-S, wherein compounding took place in a Haake kneader. The measure-ments in the Monsanto rheometer showed no crosslinking .(no significant rise in s'). Only after incorporation of a total of 10 parts by weight of Perkalink could crosslinking be observed.
As the results also entered in Table 2 show, this vulcanization test only led to a product with unsatisfactory elastomer properties, however. Furthermore, this 1 S fluorinated rubber also has an undesirably high iodine content.
Comparative example 3 In this comparative example the fluorinated rubber was produced by means of traditional precipitation polymerization and with no regulator.
Polymerization was carried out in a manner similar to Example S but with no diiodomethane being presented. 300 g of vinylidene fluoride and 200 g of hexa-fluoropropene were further added under pressure within a reaction time of 11.2 hours, which was approx. 4 hours longer than Example S.
The attempt to discharge the product as in Example 1 failed: only part of the Frigen flowed off, whilst the polymer remained in the reactor as a tough compact 2S mass and the discharge pipe blocked and a large deposit formed on the reactor wall and the stirrer. The dried rubber-like copolymer has an Mn value of 68,900 g/mol.
Le A 32 05l-Foreign Countries When vulcanization of the product was attempted as described in Example l, no crosslinking (no significant rise in s') could be observed.
Table 2: Vulcanization results and properties of the vulcanizates Example 1 3 4 5 Comparative example 1 2 MDR results s' min [dNm] 0.07 0.0l 0.01 0.02. 0.02 0.01 s' max [dNm] l8.2 9.8 7.02 l3.0 l3.4 31.2 t 90 [min] 9.9 7.4 5.8 6.1 14.5 6.2 ~
Initial mechanical properties Tensile strength [N/mmz]l3.2 l0.0 8.5 11.3 10.l 6.9 Elongation [%] 174 228 187 l65 151 26 Sao [N/mm2] 3.2 2.5 3.2 DVR
(70h / 200C) [%] 38 n.d. n.d. n.d. 39 n.d.
after hot air ageing (70h/275C) n.d. n.d. n.d.
Tensile strength [N/mmz]6.9 5.3 4.6 Elongation [%] 113 l52 69 S~o [N/mm2] 3.4 2.4 3.7 Oil ageing in BP MK n.d. n.d. n.d.
(5 x 94 h / 160C) Weight increase [%] 0.44 0.:32 0.40 Tensile strength [N/mm2]9.8 8.4 8.7 Elongation [%] l23 l65 95 SSO [N/mmz] 3.8 2.'7 4.1 n.d. = not determined
Liquid fluorinated rubber, a process for its manufacture and its use The invention relates to a new liquid fluorinated rubber, a process for its manufac-S tore and its use.
In the rubber industry there is a general desire for improved processability of the rubbers used. This relates in particular to the flow properties. The lower the vis-cosity of the crude rubber is, the simpler the processing technology, the greater the productivity and the less waste there is. These aspects are particularly important in the case of fluorinated rubbers because these are expensive rubbers which can-not be processed directly on injection moulding machines used in the rubber in-dustry.
Fluorinated rubbers with Mooney viscositiea (ML1+to at l20 ~C) > 60 can mostly only be processed by compression or transfer moulding methods. Although fluorinated rubbers with Mooney viscosities <_ 60 may be processed on special in-jection moulding machines for solid rubbers, this requires long cycle times and is also associated with a large amount of waste (flash-out), and small, complicated mouldings cannot be produced from them.
Rubbers with Mooney viscosities of 20-60 Mooney units which can be processed to produce compression mouldings according to this principle are known. These rubbers do not exhibit any distinct deterioration of the mechanical rubber proper-ties [P. Ferrandez, St. Bowers, Gummi Fasern Kunstst. 48 (l995) 626-633].
A further reduction of the molar weight for the purpose of reducing viscosity does, however, also lead to a deterioration in the vulcanizate properties (strength) of rubbers, particularly fluorinated rubbers. iJS-A 4 361 678, for example, describes liquid fluorinated rubbers which have a number average molecular weight between 900 and 10,000 g/mol and iodine contents between 1 and 30%. The products with iodine contents betlveen 4.5 and 26% described in the examples are already liquid at room temperature. Although they can be radically crosslinked via their terminal iodine atoms in the presence of peroxides and large quantities of co-crosslinking agents, the rubber properties of these elastomers are unsatisfactory.
Fluorinated rubbers in which the desired aim of low viscosity, which is required for processing according to liquid rubber injection moulding technology, is Le A 32 051-Foreign Countries - 2 - amended achieved via high iodine contents and hence low molecular weights, are known from prior application DE-P l96 221 88.9. Once again, however, low elongation values and/or strengths are the consequence.
Furthermore, these fluorinated rubbers can only be produced with a great deal of out-lay, since considerable problems and disadvantages arise during emulsion poly-merization because of secondary reactions of the molecular weight regulator in the aqueous phase and because of the formation. of water-soluble oligomers. Again, these lead to yield losses of the expensive molecular weight regulator, very long poly-merization times, high waste water load and poor product properties.
Practicable processes in non-aqueous media are not, however, known, since the solvents that are conventional for fluorinated. rubbers are very strong transfer agents for polymerization. In contrast, traditional fluorinated rubbers do not dissolve in inert solvents, such as chlorofluorocarbons, fluorocarbon or fluorinated hydrocarbon compounds. This leads to the rubber precipitating out as a compact, viscous mass during polymerization (precipitation polymerization) and, inter alia, forming wall deposits, the result of which is poor heat dissipation. This also causes problems on product discharge and low space/time yield because of greatly reduced monomer diffusion.
Liquid fluorinated rubbers which have a satisfactory property profile as regards both the viscosity relevant to processing and the; mechanical rubber properties of the end product are not known.
There was therefore a demand for liquid fluorinated rubbers which are pumpable at least at slightly elevated temperatures (60-120 ~C) and processable on traditional thermoplastics machines. These liquid fluorinated rubbers should also be readily crosslinkable and the resulting rubber components should have good mechanical and ageing properties which are very close to those of traditional solid fluorinated rubbers and should also be simple to produce.
It has now been found that a fluorinated rubber, consisting of vinylidene fluoride and optionally further monomer containing fluorine and/or not containing fluorine, and 0.5-2.5 wt.% of exclusively terminal iodine with a molecular weight Mn between 10,000 and 25,000 g/mol as well as a molecular non-uniformity of less than 1 and Le A 32 05l-Foreign Countries a complex viscosity at 100 ~C and w = 6... s 1 between 5 and l,000 Pas, has the desired property profile.
The invention therefore provides a liquid fluorinated rubber, consisting of vinyl-idene fluoride and optionally further monomers containing fluorine and/or not con-S taming fluorine as well as terminal iodine, characterized in that the iodine contents are 0.5-2.5 wt.%, the number average molecular weight (Mn) is between 10,000 and 25,000 g/mol and the molecular non-uniformity, defined as U = Mw/Mn-l, ~is less than 1 and the complex viscosity at l00 ~C and an angular frequency cu = 6.3 s 1 is between 5 and 1,000 Pa.s.
Monomers containing fluorine in the meaning of the invention are preferably fluorinated, optionally substituted ethylenes, which may contain hydrogen and/or chlorine as well as fluorine, such as vinylidene fluoride, tetrafluoroethylene and chlorotrifluoroethylene, fluorinated 1-alkenes with 2-8 carbon atoms, such as 1 S hexafluoropropene, 3,3,3-trifluoropropene, chloropentafluoropropene, hexafluoro-isobutene and/or perfluorinated vinyl ethers of the formula CF, = CF-O-X where X = Ct-C3-perfluoroalkyl or -(CF2-CFY-O)~-RF, wherein n = 1-4, Y = F or CFA
and RF = C1-C3-perfluoroalkyl.
Monomers not containing fluorine in the meaning of the invention are preferably ethylene, propene, isobutene or vinyl esters, such as vinyl acetate.
The combination of vinylidene fluoride, hexafluoropropene and optionally tetra-fluoroethylene and/or perfluorinated vinyl ethers, such as perfluoro-(methyl-vinyi-ether) is particularly preferred.
The liquid fluorinated rubbers according to the invention contain 0.5-2.5 wt.%
of iodine, which is covalently bonded to the terminal carbon atoms. This iodine is preferably introduced by molecular weight regulation with the aid of diiodo-organic compounds which act as chain-transfer agents.
Le A 32 051-Foreign Countries The number average molecular weight (Mn) of the liquid fluorinated rubber according to the invention is between 10,000 and 25,000 g/mol and was determined by membrane osmometry. The molecular non-uniformity, defined as U = Mw/Mn-l, is determined from gel permeation chromatography (GPC) measurements with RI detection in dimethylacetamide (DMAC) with the addition of 1 g/1 of Liar at 40 ~C, which were evaluated with a special calibration curve for polyethylene oxide. In the products according to the invention it lies at values < 1.
The complex viscosities of the liquid fluorinated rubber according to the invention, measured with a Bohlin rheometer of the VOR-Melt type (angular frequency cu _ 6.3 s ~) are between 5 and l,000 Pa.s at l00 ~C. They exhibit a very marked temperature dependence. The temperature index of the viscosities of the liquid fluorinated rubber according to the invention, calculated as quotient of the viscosities at 40 and 100 ~C, is preferably between I00 and 1,U00.
A further feature of the liquid fluorinated rubbers according to the invention is the fact that the complex viscosity increases preferably by the factor 5 maximum at temperatures >_ 80 ~C and reduction of the angular frequency from 50 to 0.5 s 1, i.e. virtually no structural viscosity can be observed.
The invention also provides a process for producing the liquid fluorinated rubber according to the invention, according to which vinylidene fluoride and optionally further monomers containing fluorine and/or not containing fluorine are radically polymerized in the presence of at least one diiodo-organic compound and at least one initiator in a liquid reaction phase in which the monomers, the initiator and the diiodo-organic compound are dissolved, at temperatures from 30 to 130 ~C
at a pressure in such a way that the content of the monomer in the liquid reaction phase is at least 20 wt.% and in the absence of water, wherein the fluorinated rubber formed forms a separate phase which is preferably liquid.
The diiodo-organic compounds used according to the invention for molecular weight regulation and/or as chain-transfer agents are preferably compounds of the Le A 32 05l-Foreign Countries type RI2 where R = an aliphatic hydrocarbon, fluorinated hydrocarbon, chlorofluo-rohydrocarbon or fluorocarbon group with 1-8 carbon atoms, wherein the two iodine atoms may be bonded to one or to different carbon atoms. Hydrocarbon or fluorocarbon compounds with one or four carbon atoms are particularly preferred, wherein the iodine is located at the terminal carbon atoms. Diiodomethane and/or 1,4-diiodoperfluorobutane are especially preferred. The quantity of diiodo-organic compound is preferably 0.5-2.8 parts by weight of iodine per 100 parts by weight of polymerized fluoromonomer.
Organic or fluoro-organic dialkyl peroxides, diacyl peroxides, dialkylperoxy di-carbonates, alkyl peresters and/or perketals are preferably used as initiator.
The type and quantity to be used depend on the particular reaction temperature.
The half lives of the peroxide to be selected preferably lie between 30 and 500 mins.
The quantities of initiator used are preferably between 0.1 and 1 part by weight, related to 100 parts by weight of monomers to be reacted.
I S In a preferred embodiment of the invention the polymerization is carried out in the presence of the initiator and the diiodo-organic compound and at least one inert solvent for the monomers. This reaction procedure, in which lower pressures and lower monomer use may be employed, has proved to be advantageous as regards the reaction procedure and the space/time yield. This type of polymerization is a 2-liquid phases polymerization, since the polymer arising (which is liquid under reaction conditions) is not soluble in the liquid monomer/solvent phase.
Surprisingly, the disadvantages which arise in traditional precipitation poly-merization may be avoided by this type of production.
The inert solvent used is preferably chosen in such a way that it undergoes no substantial transfer reactions under the reaction conditions. As such, certain fluorinated hydrocarbon, fluorinated chlorinated hydrocarbon or chlorofluorocarbon compounds are preferred, such as:
1,1,2,2,3,3-hexafluorocyclopentane, 1,1,2,2-tetralluorocyclobutane, 3 0 1-tri fluoromethyl-1,2,2-trifluorocyclobutane, 2,3-dihydrodecafluoropentane, perfluorobutylethane, Le A 32 05l-Foreign Countries 2,2-bis(trifluoromethyl)-1,3-dioxolane, perfluoro(tripropylamine), perfluoro(triethylamine), (methyl-2-hydrohexafluoropropyl)ether, 2-chloro-I,1,1-trifluoroethane, 1,2-dichlorotetrafluoroethane, I,1,2-trichlorotrifluoroethane and/or I,1,2,2-tetrachlorodifluoroethane.
The ratio of monomer to solvent and thf; degree of reactor filling is preferably selected in such a way that the content of the monomer in the liquid phase is at least 20 wt.% at reaction temperature. The quantity of monomer dissolved in the liquid phase may be determined, for example, from the mass balance with the aid of the partial pressures of the monomer present in the gaseous phase.
The reaction temperatures are preferably between 30 and 130 ~C. Lower tempera-tures lead to a drastic extension of the operating time and to a sharp rise in vis-I S cosity of the polymer, so that problems of mass transfer, heat dissipation and pro-duct discharge arise. The space/time yields cannot be increased substantially fur-ther with still higher temperatures, whereas the product properties deteriorate. A
particularly preferred temperature range for polymerization is 60-l20 ~C.
The pressure depends on the above-mentioned conditions and on the composition of the monomer mixture and is preferably between 10 and l50 bars. The process according to the invention is particularly preferably carried out at pressures be-tween 20 and 50 bars.
Polymerization may be carried out in the batch, continuous or batch/feed process in stirred-tank reactors, wherein the batchlfeed process is preferred.
In an embodiment of the invention, after polymerization has ended the fluorinated rubber is pressed out of the reaction vessel through a base outlet at a temperature which preferably corresponds at least to the reaction temperature. The temperature required for this step depends on the particular viscosity of the fluorinated rubber and should be increased with respect to the reaction temperature if the viscosity of the fluorinated rubber at reaction temperature does not yet permit an automatic outflow from the reactor.
Le A 32 OS 1-Foreign Countries In a further preferred embodiment of the invention, at least a part of the monomer and/or of the auxiliary solvent is still present to reduce the viscosity in the dis-charge process. The remaining monomer and/or auxiliary solvent is then separated from the product in a suitable unit and conveyed for re-use. The special ad-s vantage of this process compared with the conventional polymerization processes in aqueous dispersion, e.g. emulsion polymerization, lies in the fact that no further processing is required and, in particular, no waste water is generated.
The invention also provides the use of the liquid fluorinated rubber according to the invention as coating material or for producing rubber-elastic moulded bodies.
To produce a crosslinkable mixture as starting material for the production of rub-ber-elastic moulded bodies, fillers such as carbon black, silica, titanium dioxide, calcium silicate or barium sulphate, acid acceptors such as Ca(OH),, CaO, ZnO, MgO, and/or crosslinking chemicals, i.e. for example an organic peroxide in combination with a co-crosslinking agent such as triallyl isocyanurate (see EP-A
1 S 398 241 for example) or bisamines and/or bisphenols in combination with phase transfer catalysts and metal oxides, as described by A. L. Logothetis in Polym.
Sci. 14 (l989) 251-296, and further additives such as processing auxiliary sub stances, are added to the fluorinated rubber. These may be incorporated into the polymer both in known mixing units, such as kneaders and on two-roll mixers, and with the aid of mixers.
The improved flowability of the fluorinated rubber according to the invention permits the use of chemicals which crosslink and/or activate/trigger crosslinking, of increased reactivity, which cause speedier crosslinking. The fluorinated rubber according to the invention is preferably crosslinked radically by means of 2S conventional commercial peroxides in combination with triallyl isocyanurate, triallyl cyanurate, tri(meth)allyl isocyanurate, tetramethyltetravinylcyclotetra-siloxane, triallyl phosphite and/or N,N'-m-phenylenebismaleinimide.
l,l-bis(tert.butylperoxy)-3,3,5-trimethylcyclohexane, biscumyl peroxide, bis(1,1-di-methylpropyl)peroxide, n-butyl-4,4-di(tert.butylperoxy)valerate, 2,5-dimethyl-2,5-di-(tert.butylperoxy)hexane, 1,3-bis(2-tert.butylperoxy-isopropyl)benzene, tert.butyl-cumylperoxide, bis(tert.amyl)peroxide, bis(tert.-butyl)peroxide and/or tert.butylper-benzoate are preferably used as peroxides. The peroxides are preferably used in Le A 32 OS 1-Foreign Countries _g..
quantities of O.S-10 parts by weight, particularly preferably 1-4 parts by weight, related to l00 parts of fluorinated rubber.
Triallyl isocyanurate, triallyl cyanurate, tri(meth)allyl isocyanurate, tetramethyl-tetravinylcyclotetra-siloxane, triallyl phosphite and/or N,N'm-phenylbismaleinimide S are preferably used in quantities of O.S-12 parts by weight in each case, particularly preferably 1-6 parts by weight, related to l00 parts of fluorinated rubber.
Rubber-elastic moulded bodies may be produced both according to traditional methods conventional in the rubber industry, such as compression or transfer moulding, and on simple thermoplastic injection moulding or plunger-type metering machines. Preferably the fluorinated rubber according to the invention is introduced heated to 40 to 2S0 ~C into the thermoplastic injection moulding or plunger-type metering machine. Heated metering and conveying machines, prefer-ably heated piston pumps, are particularly suitable.
1 S Crosslinked mouldings with rubber-elastic and ageing properties which achieve the level of those made from solid fluorinated rubbers can be produced from the fluorinated rubbers according to the invention with the advantageous technology of liquid rubber processing.
The examples below serve to explain the invention without, however, having a limiting effect.
Le A 32 05l-Foreign Countries Examples:
Example 1 620 ml of 1,1,2-trichloro-2,2,l-trifluoroethane (Frigen 113, R 1l3) and 9 g of di-iodomethane (DIM, from Merck) were placed in a 4.1 I autoclave. The closed autoclave was evacuated twice accompanied by cooling, then 3 bars nitrogen pressure was applied and 10 minutes' slow stirring took place in each case.
440 g of vinylidene fluoride (VDF) and 880 g of hexafluoropropene (HFP) were placed into the evacuated autoclave and the reaction mixture was heated to 60 ~C
accompanied by stirring. When this temperature had been reached the autoclave internal pressure was 27 bars. From this, the content of dissolved monomer in the liquid phase was estimated at approx. 47 wt.%. Polymerization was initiated by the addition of 3.4 g of tert.-butylperoxypivalate as TBPPI-75-AL (solution in aliphatics, Messrs Peroxid-Chemie Gmb:Ei) with a peroxide content of 59%
dissolved in 20 g of Frigen 113. Polymerization commenced after a few minutes, as could be seen from the incipient pressure drop. During polymerization a mono-mer mixture of 60 wt.% of vinylidene fluoride and 40 wt.% of hexafluoropropene was further added under pressure in such a way that the autoclave internal pressure was constantly maintained at 27 + 0.4 bars. A total of 306 g of vinylidene fluoride and 200 g of hexafluoropropene was further metered in in this way in the course of a 12-hour reaction time. When polymerization was completed the reaction mixture was cooled and the unreacted monomer mixture re-moved from the reactor by decompression and evacuation. The remaining reactor contents (polymer + Frigen) were heated to 80 ~C accompanied by stirring. 15 minutes after the stirrer was switched off the reactor contents were completely dis-charged via a base discharge valve into a second pressure vessel underneath.
No product residues remained in the reactor.
After the product had been separated from the Frigen 113 (R 1l3) it was dried, wherein 488 g of a viscous copolymer resulted.
The following copolymer composition was determined by 19F-NMR analyses (solvent: acetone; standard: CFCl3): 20.7 mol% of hexafluoropropene, 79.3 mol%
of vinylidene fluoride.
Le A 32 05l-Foreign Countries The iodine content of the polymer, determined by elementary analysis, was 1.5 wt.%. The number average molecular weight (membrane osmosis) was l4,900 g/mol. The molecular non-uniformity U determined by GPC examinations was 0.79.
The complex viscosities were measured at different temperatures using a Bohlin rheometer of the VOR MELT type. The reaults are shown in Table 1.
To produce a crosslinkable mixture, 30 parts of carbon black MT N 900, 3 parts of calcium hydroxide, 4 parts of Perkalink 301/S0 (triallyl isocyanurate, 50%
on silica gel) and 3 parts of Luperco 130 XL,-45 (2,5-dimethyl-2,5-bis(tert.butyl-peroxy)-hexine-3; 45% in inactive fillers) were incorporated to l00 parts by weight of the fluorinated rubber copolymer on a well-cooled two-roll mixer.
To determine the crosslinking behaviour the mixtures containing peroxide were examined in a Monsanto rheometer of the MDR 2000 E type at 170 ~C (measure-ment time 30 mins).
The mixtures were pressure-vulcanized at 170 ~C and 200 bars in moulds for 1x10x10 mm plates and 6x70 mm cylinders for 30 minutes and then further vulcanized in a circulating air oven (1 hour at l60 ~C, 1 hour at 170 ~C, 2 hours at 180 ~C and 20 hours at 230 ~C). The tensile/elongation properties before and after hot air ageing (72 hours/275 ~C) and/or oil ageing (S x 94 hours in BP
MK
4437 at l60 ~C) and the compression sets (cylinder, 70 hoursl200 ~C) were deter mined on the vulcanized moulded bodies. The results are shown in Table 2.
Examples 2-5 Polymerization was carried out in a manner similar to Example 1, wherein the quantities of monomer and Frigen initially introduced were changed on the one hand and the temperature set at 40 and/or 80 ~C on the other hand, and dicyclo-hexylperoxydicarbonate (CHPC) and/or tert.-butyl-per-2-ethylhexanoate (TBPEH) were used as peroxides in the quantities below and the following results obtained:
Le A 32 05l-Foreign Countries -ll-Parameters 2 3 4 5 varied Example and results Polymerization 60 60 40 78 temperature [C]
R 113 [g] 480 980 980 980 QuantitiesVDF [g] 882 220 440 440 introduced:
HFP [g] 1760 440 880 880 DIM [g] 13 3 9 9 Reaction 37 20 20 32 pressure [bars]
Monomer 78 29 S0 45 content ' in the liquid [wt.~o]
phase Peroxide TBPPI TBPPI CHPC TBPEH
Peroxide 59 59 93 l00 content 3.5 2.67 7.4 2.5 [%]
Quantities used [g]
Time [h] 22.4 16 12.8 7 Product 600 330 483 470 yield [kg]
Iodine 1.4 0.7 1.4 1.5 content [wt.io]
Composition 80.7 78.6 80.5 79.2 VDF/I-IFP l9.3 2l.4 19.5 20.8 [Mol%]
[Mol%]
Mn [glmol] 14 400 21 1 2 13 400 U 0.86 0.93 0.87 0.64 The rubbers from Examples 3,4 and 5 were vulcanized in a similar manner to that described in Example 1, wherein 3 parts of Luperco 101 XL-45 (2,5-dimethyl-2,5-bis(tert.butylperoxy)-hexane; 45% in inactive fillers) were used as peroxide, however, instead of Luperco 130 XL-45. The results are shown in Table 2.
Le A 32 OS 1-Foreign Countries Table l: Complex viscosities rl* at different tempertures, measured with a VOR-Melt Bohlin rheometer (angular frequency c~ = 6,3 s'1), in Pas in each case and quotients of the values measured at 80~C at w = 0,5 and 50 s 1 Example 1 2 3 4 5 Comparative example( 1 2 40C 31500 2730023200 l12007860 12500l470 80C 370 360 R20 262 4l0, 420 115 100C 110 105 2 00 74 52.6 l60 2.2 l20C 33 30 E>7 32 34 81 1.0 140C 12 10 2 5 17.2 20.8 45 0.43 r~*(40C)/rl*(100C)286 260 l.16 151 149 78 668 rl*(80C;O.Ss I)/ 1.2 1.2 1.1 1.9 1.2 3.1 1.2 r~*(80C;SOs 1) Le A 32 05l-Foreign Countries Example 6 Polymerization was carried out in a manner similar to that of Example 1, wherein 15.2 g of diiodoperfluorobutane (DIFPB, Fluorochem Ltd) were used, after prior purification by shaking out with aqueous sodium thiosulphate solution, instead of the diiodomethane, and the following results were obtained:
Time [h] 11.2 'Product yield ......_..._..__[k~j_._.........'4~0 '.........._............
...........
Iodine content."...._.............._.........1...~............_..........._..
[~.%] _.....
~Composition:'..................................._._....._....................
................................_.
S VDF [Mol%] 79 HFP [Mol%] 21 ..~ .._.___.._........._...............................__.[~~ofj....... ..1.~
..000 ..........._.....
..U~__.._..................._.._..._.................._._..._.............._...
........ . Ø;
g.l ..........................
Example 7 Polymerization was carried out in a manner similar to Example 6, wherein 633 ml of perfluoro(tripropyl)amine were used instead of the Frigen 113 (R 113) and 11.9 g of DIPFB.
After a total operating time of 15 hours, 360 g of a polymer which had high vis cosity at room temperature and low viscosity above 70 ~C and an iodine content of 1.5% was isolated.
Le A 32 05l-Foreign Countries Comparative example 1 (Fluorinated rubber, produced by emulsion polymerization).
25.2 kg of deionized water and 60.2 g of lithium perfluoro-octylsulphonate were placed in a 36 1 autoclave. 40 g of oxalic acid dihydrate and 31 g of diiodo-methane (Merck) were dissolved therein, wherein a pH value of 3.2 established in the entire aqueous initial material presented. The closed autoclave was evacuated four times, then 3 bars nitrogen pressure ;vas applied and slow stirring took place for 10 minutes in each case. 269 g of vinylidene fluoride and 368 g of hex-afluoropropene were placed into the evacuated autoclave and the reaction mixture was heated to 25 ~C accompanied by stirring. When this,temperature had been reached the autoclave internal pressure was 9.4 bars. Polymerization was initiated by the addition of 53 ml of an aqueous solution which contained 20 g/l of potassium permanganate. Immediately after this one addition the said solution was continuously further metered at a rate of 39 ml/hr. Polymerization 1 S commenced after 26 minutes, as could be seen from the incipient pressure drop.
During polymerization a monomer mixture of 60 wt.% of vinylidene fluoride and 40 wt.% of hexafluoropropene was further added under pressure in such a way that the autoclave internal pressure was constantly maintained at 9.4 t 0.2 bars.
After Z00 g of monomer conversion in each case, 30 ml of a solution of diiodomethane in 1,1,2-trichloro-1,2,2-trifluoroethane (100 g/1) were also added.
A total of 944 g of vinylidene fluoride and 622 g of hexafluoropropene, and 45 g of diiodomethane, were pumped in in this way in the course of a 15-hour reaction time. To end polymerization, the permanganate metering was ceased, the unre-acted monomer mixture removed from the reactor by decompression and evacuation and the remaining autoclave <:ontents cooled down. 1340 g of a soft rubber-like copolymer was isolated from the latex by freeze-coagulation, washing and drying for 24 hours at 50 ~C in a vacuum drying cabinet.
The following copolymer composition was determined by 19F-NMR analyses:
19.8 mol% of hexafluoropropene, 80.2 mol% of vinylidene fluoride.
The iodine content of the polymer is 2.'7 wt.%. The number average molecular weight (membrane osmosis) is approx. 9,000 g/mol, the non-uniformity U is 1.2.
The complex viscosities measured on this product are also entered in Table I.
Le A 32 051-Foreign Countries From this it can be seen that this product has higher viscosities and greater dependence on the shear rate gradient at temperatures above 80 ~C despite the lower molecular weight.
The resulting rubber was vulcanized as described in Example 1. The results, which are also shown in Table 2, show that the vulcanized test bodies exhibit lower elongation values in both the initial state and after the ageing tests.
Comparative example 2 2.78 kg of deionized water and 4.5 g of lithium perfluoro-octylsulphonate were placed in a 4.1 1 autoclave. 40 g of 1.,4-diiodoperfluorobutane were dissolved therein. The closed autoclave was evacuated four times, then 3 bars nitrogen pressure was applied and 10 minutes' slow stirring took place in each case. 27 g of vinylidene fluoride and 53 g of hexafluoropropene were placed into the evacuated autoclave and the reaction mixW re was heated to 80 ~C accompanied by stirring. When this temperature had been reached the autoclave internal pressure was 15 bars. Polymerization was initiated by the addition of 2.8 g of ammonium peroxydisulphate dissolved in 20 g of water. Polymerization commenced after 7 minutes, as could be seen from the incipient pressure drop. During polymerization a monomer mixture of 60 wt.% of vinylidene fluoride and 40 wt.% of hexafluoro-propene was further added under pressure in such a way that the autoclave internal pressure was constantly maintained at 17 _~ 0.2 bars. A total of 93 g of vinylidene fluoride and 216 g of hexafluoropropene was further metered in in this way in the course of a 6-hour reaction time. To e:nd polymerization, the reactor contents were cooled down and the unreacted monomer mixture removed from the reactor by decompression and evacuation. The latex was coagulated by stirring into a 6%
calcium chloride solution, washed with water and dried in a vacuum drying cabinet for 24 hours at 50 ~C, wherein '280 g of a viscous copolymer were ob-tained.
Le A 32 OS 1-Foreign Countries Iodine content [wt.%] ~ 4.8 Composition:
VDF [Mol%] 8c).5 HFP [Mol%] 1'7.3 S -(CFZ)4- [Mol%] 2.2 ...M .....-..............................._.._.._-..__._.._.[~mol~...__ ..5Z00 I U I 1.0 The product was initially vulcanized in a similar manner to the products from Ex-amples 3-S, wherein compounding took place in a Haake kneader. The measure-ments in the Monsanto rheometer showed no crosslinking .(no significant rise in s'). Only after incorporation of a total of 10 parts by weight of Perkalink could crosslinking be observed.
As the results also entered in Table 2 show, this vulcanization test only led to a product with unsatisfactory elastomer properties, however. Furthermore, this 1 S fluorinated rubber also has an undesirably high iodine content.
Comparative example 3 In this comparative example the fluorinated rubber was produced by means of traditional precipitation polymerization and with no regulator.
Polymerization was carried out in a manner similar to Example S but with no diiodomethane being presented. 300 g of vinylidene fluoride and 200 g of hexa-fluoropropene were further added under pressure within a reaction time of 11.2 hours, which was approx. 4 hours longer than Example S.
The attempt to discharge the product as in Example 1 failed: only part of the Frigen flowed off, whilst the polymer remained in the reactor as a tough compact 2S mass and the discharge pipe blocked and a large deposit formed on the reactor wall and the stirrer. The dried rubber-like copolymer has an Mn value of 68,900 g/mol.
Le A 32 05l-Foreign Countries When vulcanization of the product was attempted as described in Example l, no crosslinking (no significant rise in s') could be observed.
Table 2: Vulcanization results and properties of the vulcanizates Example 1 3 4 5 Comparative example 1 2 MDR results s' min [dNm] 0.07 0.0l 0.01 0.02. 0.02 0.01 s' max [dNm] l8.2 9.8 7.02 l3.0 l3.4 31.2 t 90 [min] 9.9 7.4 5.8 6.1 14.5 6.2 ~
Initial mechanical properties Tensile strength [N/mmz]l3.2 l0.0 8.5 11.3 10.l 6.9 Elongation [%] 174 228 187 l65 151 26 Sao [N/mm2] 3.2 2.5 3.2 DVR
(70h / 200C) [%] 38 n.d. n.d. n.d. 39 n.d.
after hot air ageing (70h/275C) n.d. n.d. n.d.
Tensile strength [N/mmz]6.9 5.3 4.6 Elongation [%] 113 l52 69 S~o [N/mm2] 3.4 2.4 3.7 Oil ageing in BP MK n.d. n.d. n.d.
(5 x 94 h / 160C) Weight increase [%] 0.44 0.:32 0.40 Tensile strength [N/mm2]9.8 8.4 8.7 Elongation [%] l23 l65 95 SSO [N/mmz] 3.8 2.'7 4.1 n.d. = not determined
Claims (11)
1. Liquid fluorinated rubber, consisting of vinylidene fluoride and at least one further monomer containing fluorine and/or not containing fluorine as well as exclusively terminal iodine, characterized in that the iodine contents are 0.5-2.5 wt.%, the number average molecular weight (Mn) is between 10,000 and 25,000 g/mol and 'the molecular non-uniformity is less than 1 and the complex viscosity at 100 ~C and .omega. = 6.3 s-1 is between 5 and 1,000 Pa.s.
2. Fluorinated rubber according to Claim 1, characterized in that the complex viscosity increases by the factor 5 maximum at temperatures ~ 80 ~C
and reduction of the angular frequency .omega. from 50 to 0.5 s-1.
and reduction of the angular frequency .omega. from 50 to 0.5 s-1.
3. Fluorinated rubber according to one of Claims 1 or 2, characterized in that the temperature index of the complex viscosity, calculated as quotient of the viscosities at 40 and 100 ~C, is between 100 and 1,000.
4. Process for producing liquid fluorinated rubber according to one or more of Claims 1 to 3, characterized in that vinylidene fluoride and optionally further monomers containing fluorine and/or not containing fluorine are radically polymerized in the presence of at least one diiodo-organic compound and at least one initiator in a liquid reaction phase in which the monomers, the initiator and the dioodo-organic compound are dissolved, at temperatures from 30 to 130 ~C
at a pressure in such a way that the content of the monomer in the liquid reaction phase is at least 20 wt.% and in the absence of water, wherein the fluorinated rubber formed forms a separate phase.
at a pressure in such a way that the content of the monomer in the liquid reaction phase is at least 20 wt.% and in the absence of water, wherein the fluorinated rubber formed forms a separate phase.
5. Process according to Claim 4, characterized in that the quantity of diiodo-organic compound is 0.5 - 2.8 pans by weight of iodine per 100 parts by weight of polymerized fluoromonomer.
6. Process according to one of Claims 4 to 5, characterized in that organic or fluoro-organic peroxides from the group of the dialkyl peroxides, diacyl peroxides, dialkylperoxydicarbonates, alkyl peresters or perketals are used as initiator.
7. Process according to one or more of Claims 4 to 6, characterized in that the reaction is carried out in the presence of at least one inert solvent for the monomers.
8. Process according to one or more of Claims 4 to 7, characterized in that diiodomethane and/or 1,4-diiodoperfluorobutane is used as diiodo-organic compound.
9. Process according to one or more of Claims 4 to 8, characterized in that after polymerization has ended the fluorinated rubber is pressed out of the reaction vessel through a base outlet at a temperature which corresponds at least to the reaction temperature.
10. Process according to Claim 9, characterized in that at least a part of the monomer and/or of the auxiliary solvent used during polymerization is still present during the discharge process.
11. Use of the fluorinated rubber according to one or more of Claims 1 to 3 as coating material or for producing robber-elastic moulded bodies.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19640972A DE19640972A1 (en) | 1996-10-04 | 1996-10-04 | Liquid fluororubber, a process for its production and its use |
| DE19640972.1 | 1996-10-04 | ||
| PCT/EP1997/005191 WO1998015583A1 (en) | 1996-10-04 | 1997-09-22 | Liquid fluoric rubber |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2268072A1 true CA2268072A1 (en) | 1998-04-16 |
Family
ID=7807878
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002268072A Abandoned CA2268072A1 (en) | 1996-10-04 | 1997-09-22 | Liquid fluoric rubber |
Country Status (8)
| Country | Link |
|---|---|
| EP (1) | EP0929584B1 (en) |
| JP (1) | JP2001508474A (en) |
| AU (1) | AU4556197A (en) |
| CA (1) | CA2268072A1 (en) |
| DE (2) | DE19640972A1 (en) |
| TW (1) | TW491859B (en) |
| WO (1) | WO1998015583A1 (en) |
| ZA (1) | ZA978863B (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8835551B2 (en) | 2007-09-14 | 2014-09-16 | 3M Innovative Properties Company | Ultra low viscosity iodine containing amorphous fluoropolymers |
| EP2443194B1 (en) | 2009-06-19 | 2016-05-18 | 3M Innovative Properties Company | Low temperature curable amorphous fluoropolymers |
| US9458272B2 (en) | 2010-12-20 | 2016-10-04 | Solvay Specialty Polymers Italy S.P.A. | Low viscosity fluoroelastomers |
| WO2017216035A1 (en) * | 2016-06-13 | 2017-12-21 | Solvay Specialty Polymers Italy S.P.A. | Curable fluoroelastomer composition |
| US11739243B2 (en) | 2018-12-21 | 2023-08-29 | Honeywell International Inc. | Azeotrope or azeotrope-like compositions of 1,2,2-trifluoro-1-trifluoromethylcyclobutane (TFMCB) and applications thereof |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19740633A1 (en) * | 1997-09-16 | 1999-03-18 | Bayer Ag | Production of low-viscosity fluoro-rubber |
| DE19924439A1 (en) * | 1999-05-28 | 2000-11-30 | Bayer Ag | Fast cross-linking fluoropolymer |
| KR20030095405A (en) * | 2001-05-14 | 2003-12-18 | 이 아이 듀폰 디 네모아 앤드 캄파니 | Polymer-liquid compositions useful in ultraviolet and vacuum ultraviolet uses |
| US7129009B2 (en) | 2002-05-14 | 2006-10-31 | E. I. Du Pont De Nemours And Company | Polymer-liquid compositions useful in ultraviolet and vacuum ultraviolet uses |
| CN101171269A (en) | 2005-05-02 | 2008-04-30 | 大金工业株式会社 | Method for producing fluorine-containing polymer and fluorine-containing polymer produced by such method |
| JP6714492B2 (en) * | 2015-12-24 | 2020-06-24 | 信越化学工業株式会社 | Organic film forming compound, organic film forming composition, organic film forming method, and pattern forming method |
| CN115215956A (en) * | 2022-07-20 | 2022-10-21 | 北京化工大学 | Low-molecular-weight hydroxyl-terminated carboxyl fluorocarbon elastomer, and preparation method and vulcanization method thereof |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5657811A (en) * | 1979-10-17 | 1981-05-20 | Daikin Ind Ltd | Preparation of liquid fluorine-containing polymer |
| CA1248286A (en) * | 1984-08-09 | 1989-01-03 | Paul G. Bekiarian | Improved fluoropolymer |
| US5214106A (en) * | 1991-05-22 | 1993-05-25 | E. I. Du Pont De Nemours And Company | Cured fluoroelastomer compositions |
| US5231154A (en) * | 1992-09-25 | 1993-07-27 | E. I. Dupont De Nemours And Company | Iodine containing chain transfer angents for fluoropolymer polymerizations |
| JP3327016B2 (en) * | 1994-12-06 | 2002-09-24 | ダイキン工業株式会社 | Fluororubber copolymer excellent in low-temperature sealability and its curing composition |
| CN1290879C (en) * | 1995-02-06 | 2006-12-20 | 纳幕尔杜邦公司 | Amorphous tetrafluoroetylene-hexafluoropropylene copolymers |
| DE19622188A1 (en) * | 1996-06-03 | 1997-12-04 | Bayer Ag | Fluororubber, a process for the production and its use and a process for the production of fluoroelastomer moldings and / or coatings |
-
1996
- 1996-10-04 DE DE19640972A patent/DE19640972A1/en not_active Withdrawn
-
1997
- 1997-09-22 AU AU45561/97A patent/AU4556197A/en not_active Abandoned
- 1997-09-22 DE DE59703517T patent/DE59703517D1/en not_active Expired - Fee Related
- 1997-09-22 WO PCT/EP1997/005191 patent/WO1998015583A1/en active IP Right Grant
- 1997-09-22 JP JP51712298A patent/JP2001508474A/en not_active Ceased
- 1997-09-22 CA CA002268072A patent/CA2268072A1/en not_active Abandoned
- 1997-09-22 EP EP97943879A patent/EP0929584B1/en not_active Expired - Lifetime
- 1997-09-24 TW TW086113864A patent/TW491859B/en not_active IP Right Cessation
- 1997-10-03 ZA ZA9708863A patent/ZA978863B/en unknown
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8835551B2 (en) | 2007-09-14 | 2014-09-16 | 3M Innovative Properties Company | Ultra low viscosity iodine containing amorphous fluoropolymers |
| EP2443194B1 (en) | 2009-06-19 | 2016-05-18 | 3M Innovative Properties Company | Low temperature curable amorphous fluoropolymers |
| US9458272B2 (en) | 2010-12-20 | 2016-10-04 | Solvay Specialty Polymers Italy S.P.A. | Low viscosity fluoroelastomers |
| WO2017216035A1 (en) * | 2016-06-13 | 2017-12-21 | Solvay Specialty Polymers Italy S.P.A. | Curable fluoroelastomer composition |
| CN109476875A (en) * | 2016-06-13 | 2019-03-15 | 索尔维特殊聚合物意大利有限公司 | Curable fluoroelastomer composition |
| US11739243B2 (en) | 2018-12-21 | 2023-08-29 | Honeywell International Inc. | Azeotrope or azeotrope-like compositions of 1,2,2-trifluoro-1-trifluoromethylcyclobutane (TFMCB) and applications thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2001508474A (en) | 2001-06-26 |
| DE19640972A1 (en) | 1998-04-16 |
| EP0929584B1 (en) | 2001-05-09 |
| AU4556197A (en) | 1998-05-05 |
| WO1998015583A1 (en) | 1998-04-16 |
| EP0929584A1 (en) | 1999-07-21 |
| ZA978863B (en) | 1998-04-17 |
| TW491859B (en) | 2002-06-21 |
| DE59703517D1 (en) | 2001-06-13 |
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