CARBON BASED INITIATORS FOR POLYMERIZATION

AND TELOMERIZATION OF VINYL MONOMERS

FIELD OF THE INVENTION This invention relates to carbon based initiators for polymerization and telomerization reactions of vinyl monomers.

TECHNICAL BACKGROUND

Intercalates with graphite and fluorographites have been used to catalyze cationic reactions, including polymerization, of nonfluorinated substrates. Applicants have located no reference to the use of fluorographites or fluorinated carbons as polymerization or telomerization initiators. SUMMARY OF THE INVENTION

This invention concerns a polymerization or telomerization process for preparing polymers or telomers from vinyl monomers comprising polymerizing or telomerizing vinyl monomers in the presence of an initiator comprising a fluorinated carbon and in the optional presence of a solvent.

Specifically, the invention concerns a polymerization process for preparing polymers and oligomers from vinyl monomers of the structure X2C=CYZ, where X is selected from the group consisting of H and F, Y is selected from the group consisting of H, F, and CH3, and Z is selected from the group consisting of H, F, OR _f ¹ , Cl, CH ₂ OH, R _f ', R, and CC^R', wherein R _f ' is a perfluoroalkyl of 1 to 4 carbon atoms; R is alkyl of 1 to 4 carbon atoms and R' is alkyl or polyfluoroalkyl of 1 to 4 carbon atoms; comprising polymerizing said vinyl monomers in the presence of fluorinated carbons, in the optional presence of a solvent.

"Fluorinated carbons" include fluorographites and fluorinated cokes, as well as graphite or fluorographite

intercalated with SbFs _f VF ₅ or F ₂ . The reaction temperature range is -10°C to 250°C, depending upon the reactants.

By "oligomer" herein is meant a polymer made of two, three or four monomer units.

DETAILS OF THE INVENTION

In the polymerization of vinyl monomers solvent is generally not needed. However, in certain cases solvent may be useful. Suitable solvents for these processes are stable under reaction conditions, and include polyfluorinated ethers, perfluoroethers, polyfluoroalkanes, and perfluoroalkanes, such as perfluorodimethylcyclobutane (also referred to as F-dimethylcyclobutane) , CF3CF ₂ CF ₂ OCHFCF3, perfluorobutyltetrahydrofuran, perfluoro-n-hexane,

CFCI2CF2CI, and CF3CHFCHFCF2CF3. Where the abbreviation "F-" appears in the specification, it denotes "perfluoro" . Excess telogen may also serve as the solvent . Fluorinated carbons, including fluorographites and fluorinated cokes, and graphites or fluorographites intercalated with SbFs, VF ₅ or F ₂ initiate a variety of polymerizations and telomerizations. The fluorographites are especially useful herein in that products such as polytetrafluoroethylene (PTFE) , tetrafluoroethylene/hexafluoropropene copolymer (FEP), tetrafluoroethylene/perfluoro(propyl vinyl ether) (PFA), R _f I (Telomer A) , and R _F CH2CH2l (Telomer B) are formed cleanly and in good conversion. R _f is a perfluoroalkyl of 1 to 10, preferably 1 to 4, carbon atoms.

Fluorinated carbons are prepared by fluorination of various forms of carbon, including carbon blacks, cokes and graphites. Many of these forms are commercial products. For example, Allied Corporation provides under the Accufluor® trademark CF _X , Series 1000, based

on the reaction of a coke feedstock with elemental fluorine at high temperture to incorporate up to about 63 wt% of fluorine and corresponding to the composition of CFι.08- Another of Allied Corporation's Accufluor® CF _X , Series 2000 is based upon fluorination of conductive black to give 11-65% fluorine content, or CFo.o8~CF_.i ₇ in empirical formula. Ozark-Mahoning provides Fluorographite® products of the approximate composition range 27-63.5 wt% fluorine, or CFo. ₂₅ ~CFι.ι ₇ , while their coke based carbon monofluoride product has a composition of CF ₀ .9-CF1.05.

The carbon being fluorinated can be of various shapes such as powder, large particles or fibers. Fluorination can be carried out to various levels of fluorine content in the catalyst by controlling variables in the fluorination process, especially the ratio of fluorine to carbon reactants, temperature, and time. Graphite in which fluorine gas is intercalated, rather than covalently bound, can also be prepared. Nakajima, T.; Watanabe, N.; Kameda, I.; Endo, M.,

Carbon, 1986, Vol. 24, 343-351 describe these processes.

The polymerization or telomerization results in formation of products varying in size and molecular weight from high polymers to 1:1 telogen/olefin adducts. Telomerization is a process yielding a low molecular weight polymer consisting of a chain of a limited number of units terminated at each end by a radical of a different compound (the telogen) . See Oxford English Dictionary, Second Ed., Clarendon, Oxford, 1989. The telomerization reaction proceeds as a polymerization reaction between two substances providing respectively the terminal groups and internal linkages of the resulting telomer molecule; e.g., CCI ₄ + CH2CH ₂ —> Cl (CH ₂ CH ₂ )nCCl3. See also Hackh's Chemical Dictionary, 1969, McGraw Hill, Inc., p. 664. Vinyl monomers and

comonomers used for polymerizations include but are not limited to, CF ₂ =CF ₂ , CF ₂ =CFCF ₃ , CF2=CFOCF ₂ CF ₂ CF3, CF ₂ =CFOCF ₃ , CF ₂ =CH ₂ , CH ₂ =CHC0 ₂ CH3, CH ₂ =C (CH3) CO ₂ CH3, CH2=C(CH3)Cθ2CH(CF3)2, CH2=CHC02CH(CF3) ₂ and CH2=CH2. Those used for telomerizations are CF ₂ =CF ₂ , CF ₂ =CFC1, CF ₂ =CHF, CF ₂ =CH ₂ , CH ₂ =CH ₂ , CH ₂ =CHCH ₃ , CH ₂ =CHCH OH, and CH2=CHC ₄ F9. Included are monomers of the general formula X ₂ C=CYZ, where X=H or F, Y=H, F or (in some cases) CH3, and Z=H, F, OR _F , Cl, CH ₂ OH, R _f ¹ , R, or C0 ₂ R* where R _f ' is perfluoroalkyl of 1 to 4 carbon atoms, R is alkyl of 1 to 4 carbon atoms, and R ¹ is alkyl or polyfluoroalkyl of 1 to 4 carbons.

Telogens suitable herein are of the general formulas RH, RI, RBr and RC1, where R can be hydrocarbyl or polyhaloalkyl, including, for example, CF3CF ₂ I, CF3CF2CF2I, C2F5I, F(CF ₂ ) ₄ I, F(CF ₂ ) ₆ I, F(CF ₂ ) ₈ I, (CF ₃ ) ₂ CFI, BrCF ₂ CFClBr, CF ₂ Br ₂ , CCI ₄ , methylcyclohexane, CF3OCF2CF ₂ I, C3F7OCF2CF2I, C1CF ₂ CFC1I, I(CF ₂ )3l, I(CF ₂ )4l and BrCF2CF2Br. In a preferred embodiment of the process, the telogen is F(CF ₂ ) _n I, where n is 2 to 8, and the monomer is TFE or ethylene.

Initiator compositions can vary. Carbons fluorinated from a low level (e.g. 4.5% surface fluorinated graphite fibers) to high levels (e.g. 63% F from coke and 65% from conductive carbon) have been shown to serve as initiators herein. Furthermore, intercalates of SbFs with graphites as well as with fluorographites have been shown to be even more active than the parent fluorographites as initiators of fluoroolefin reactions. Intercalates with other materials (e.g., VF ₅ , F ₂ ) also serve as initiators.

Carbon-reinforced polymeric products are obtained directly. Advantages of the present catalysts for telomerizations to make liquid and/or organic-soluble

products include the use of easily isolated initiators which can be reused/regenerated and the ready adaptability to flow reactors. The fluorographite and fluorinated carbon initiators have been shown to remain active after storage under ambient conditions for long periods of time and are thus convenient to use.

Reaction temperature can vary from -10°C to 250°C for polymerizations with the fluorinated carbons, depending on the reactants, while the intercalates can be used from about -10°C to about 120°C. Reaction temperatures for the telomerizations can vary from 25-150°C. Reaction time can be from a few seconds to in excess of one day depending upon variables such as temperature and the reactivity of the monomer (s) employed. Pressures can be subatmospheric to about 100 atmosphere, preferably from 1-100 atmospheres (105-107 pa) .

Polymers produced by the polymerization process described herein are useful as water repellants and materials with high temperature resistance. Telomers produced are useful as intermediates in the production of chemically inert and temperature resistant materials.

EXAMPLES EXAMPLE 1

TFE/PMVE Copolymer with CFrj.8 Initiator

A 400 mL Hastelloy tube charged with 2.0 g of CFo.8, 50 L of F-dimethylcyclobutane, 66 g (0.4 mol) of CF ₂ =CFOCF3, and 50 g (0.5 mol) of CF ₂ =CF ₂ was agitated at 80°C for 12 hr. The crude grey product was mixed briefly in a blender with 300 mL of methanol, filtered off and dried at 100°C (0.2 mm) to afford 51.6 g of copolymer. Differential Scanning Calorimetry (DSC) indicated the product to be amorphous, while Thermogravimetric analysis (TGA) showed only slight

weight loss to 450°C. In a melt indexer at 372°C under a 15 kg weight, 1.46 g of tough black copolymer was extruded in 15 min.

EXAMPLE 1A Reuse of Initiator/Polymer Blend as Initiator

Ten grams of the product from Example 1, calculated to contain 0.4 g of used initiator mixed with 9.6 g of CF ₂ =CF ₂ CF ₂ =CFOCF3 copolymer, was charged to a 400 L metal tube along with 66 g (0.4 mol) of CF ₂ =CFOCF3, 50 g (0.5 mol) of CF2=CF2, and 50 L of HFP cyclodimer. The tube was agitated at 100°C for 12 hr. The crude product was dried at 100°C (0.2 mm), yielding 56.4 g of copolymer. Differential Scanning Calorimetry (DSC) showed a p 286.6°C. EXAMPLE 2

TFE/HFP Copolymer with SbFs/CFp.25 Initiator

A 2.0 g sample of 30 wt % SbFs on CF_. ₂₅ was washed twice with F-n-hexane and charged to 400 mL Hastelloy tube along with 50 mL of F-n-hexane, 75 g (0.50 mol) of CF ₂ =CFCF3, and 50 g (0.50 mol) of CF ₂ =CF ₂ . Reaction was conducted at 25°C for 4 hr, 50°C for 4 hr, and finally 100°C for 4 hr. The crude product, 135 g, was ground in a blender with 500 mL of methanol, filtered and stripped of volatiles under vacuum, ending at 100°C (0.2 mm) for 4 hr. TGA: no weight loss to 450°C. DSC: mp 312.8°C shows the presence of CF3CF=CF2.

EXAMPLE 3 TFE/PMVE Copolymer with SbFs/Graphite Initiator

A 240 mL metal tube charged with 1.0 g of 72% SbFs on graphite, 50 mL of F-dimethylcyclobutane, 25 g

(0.25 mol) of CF ₂ =CF ₂ , and 33 g (0.2 mol) of CF ₂ =CFOCF ₃ was heated at 80°C for 10 hr to give 96.9 g of crude grey polymer. Removal of volatiles at 100°C (0.2 mm) afforded 38.2 g of grey polymer. TGA showed zero weight loss to 475°C. DSC: mp 295.8°C. In a melt indexer at

371°C with a 15 kg weight, 0.09 g of tough, dark grey polymer extruded in 15 min.

EXAMPLE 4 TFE Polymer with SbFs/Graphite Initiator in Water Suspension

A 2.0 g sample of 72% SbFs on graphite was washed well with F-dimethylcyclobutane to remove any exterior

S Fs and charged to a 400 mL Hastelloy tube along with

100 mL of degassed distilled water, 10 mL of F-dimethyl- cyclobutane, and 50 g (0.50 mol) of CF ₂ =CF2. The tube was shaken at 25°C for 8 hr, then at 60°C for 4 hr. The grey homopolymer weighed 33.3 g after having been filtered off and dried in a stream of air.

EXAMPLE 5 TFE/VF2 Copolymer with CFp.s Initiator

Two grams of CFo.8, 50 mL of F-dimethylcyclobutane, 32 g (0.50 mol) of CH ₂ =CF ₂ , and 50 g (0.50 mol) of CF ₂ =CF2 were charged to a 240 mL tube and heated at 120°C for 12 hr. The reaction mixture was filtered and the black polymer so isolated was dried at 100°C

(0.2 mm) for 4 hr to give 13.4 g of copolymer. DSC: mp 185.3°C.

EXAMPLE 6 Fluorination of Graphite Fiber Hercules AS1815 graphite fibers cut to 1/4" length were extracted repeatedly with methanol to dissolve sizing, then dried under vacuum. A sample of the graphite fibers, 20.5 g or 1.71 g-atom, was charged to a 400 mL Hastelloy tube. The tube was evacuated at 25°C and pressured to 300 psig (2.07 x 10 ⁶ Pa) with 25/75

F ₂ /N ₂ (calcd. 0.089 mol, 3.4 g, of F2) . The reaction was carried out static at 200°C for 6 hr. Gases were vented and the fibers held at 25°C (0.2 mm) for 4 hr. Anal.: Found, 4.47% F.

EXAMPLE 7 TFE Polymer from Fluoroσraphite Fiber Initiator Five grams of the surface-fluorinated fiber from Example 6, 50 mL of F-dimethylcyclobutane, and 50 g (0.50 mol) of CF ₂ =CF ₂ were reacted in a 240 L metal tube for 6 hr at 25°C, then 6 hr at 60°C. The resulting moist grey polymer was dried at 100°C (0.2 mm) for 4 hr to give 54.0 g of polymer-coated fiber.

EXAMPLE 8 TFE Polymer o Limited Molecular Weight

A 400 L metal tube charged with 175 mL of F-di¬ methylcyclobutane, 2.0 g of CFo.8 _/ 0.9 g of methylcyclohexane, and 40 g (0.40 mol) of CF ₂ =CF ₂ was heated at 150°C for 10 hr. The moist solid product was mixed in a blender with 300 mL of methanol, filtered, and the filter cake was dried for 4 hr at 100°C (0.2 mm) . The resulting high telomer weighed 16.3 g.

EXAMPLE 9 TFE Polymer from CFI.QS

The fluorinated carbon initiators used in examples above were fluorographites . This example uses fluorinated coke, shown by X-ray diffraction to contain no graphitic structure. A 240 mL tube charged with 2.0 g of CFi.oβ from fluorination of coke, 50 mL of F-dimethylcyclobutane, and 50 g (0.50 mol) of CF2=CF2 was shaken at 25-40°C for 6 hr. The product was dried at 100°C (0.2 mm) for 4 hr to afford 49.5 g of white polymer. EXAMPLE 10

TFE/HFP Copolymer with CFp.2 ₅ Initiator in Water Suspension

Two grams of CFø.2 ₅ 100 ^mL of degassed, distilled water, 75 g (0.50 mol) of CF ₃ CF=CF , and 35 g (0.35 mol) of CF ₂ =CF ₂ were reacted in a 400 mL tube for 8 hr at

100°C. The dried grey product polymer, 39.1 g, had mp 310.7°C. TGA showed no weight loss to 450°C and 5% loss to 500°C. In the melt indexer, 0.04 g of tough black polymer was extruded at 372°C in 15 min with 15 kg weight.

EXAMPLE 11 Telomer A Synthesis with SbF ₅ /CFp.8 Intercalate as Initiator

In a 240 mL stainless steel shaker tube was placed 4 g of 40% SbFs in fluorographite CF_.8 and 100 g

(0.29 mol) of C ₄ F9I (containing 5% of C2F ₅ I) . The tube was cooled to -78°C, evacuated and loaded with 10 g (0.1 mol) of tetrafluoroethylene (TFE) . The reaction vessel was shaken at 80°C. Significant pressure drop (90 psi) was observed in the first 2 hr of the reaction. After 18 hr the shaker tube was unloaded. The crude product (108 g) was filtered, leaving 7 g of solid (initiator coated with PTFE) and 100 g of liquid, which according GC was a mixture of C ₄ F9I and telomer iodides C ₄ F9(CF2CF ₂ ) _n I (wt-%) : C ₂ F5I, 5.1; C ₄ F9I, 76.1; n=l,

11.6; n=2, 4.2; n=3, 1.24; n=4, 0.35; n=5, 0.11. Conversion of TFE was 100%, conversion of C ₄ F ₉ I was 19%.

EXAMPLE 12

Telomer A Synthesis with CFp.8 Fluorographite as Initiator

In a test as described in Example 10, 4 g of fluorographite CFQ.8 was used. The reaction vessel was shaken for 18 hr at 120°C. The product was isolated as above. After filtration there was obtained 7.5 g of fluorographite coated with PTFE and 96 g of a mixture of C ₄ F9I and telomers C ₄ F9 (CF2CF2) _n I (wt-%) : C2F ₅ I, 4.4; C ₄ F9I, 75.6; n=l, 11.3; n=2, 4.72; n=3, 1.65; n=4, 0.55; n=5, 0.25; n=6, 0.13; n=7, 0.07. Conversion of TFE was 100%; C ₄ F9I, 22.4%.

EXAMPLE 13

Telomer B Synthesis with CFQ.8 Initiator and TFE Co-initiator

4 g of fluorographite CFQ.8 was placed in a 400 mL stainless steel shaker tube, and the tube was evacuated and charged at -40°C with 100 g (0.41 mol) of C2F ₅ I, 10 g (0.36 mol) of ethylene and 5 psig (3 x 10 ² Pa) of CF ₂ =CF ₂ (about 0.3-0.5 g) . The reaction vessel was shaken at 80°C. Significant pressure drop (340 psi; i.e. 2 x 10 ⁶ Pa) was observed in the first 2 hr. After 18 hr, the shaker tube was unloaded, the product was filtered and distilled to afford 86 g (87%) of C2F5CH2CH2I.

EXAMPLE 14 Reaction of CF2BrCF ₂ Br with C ₂ H ₄

In a reaction run as in Example 13, 130 g (0.5 mol) of BrCF ₂ CF ₂ Br, 4 g of fluorographite CFp.β and 6 g (0.2 mol) of CH ₂ =CH ₂ was used. The reaction vessel was shaken at 150°C. After 16 h, the shaker tube was unloaded and the reaction mixture was filtered. There was recovered 4.1 g of initiator and 116 g of the mixture (GC, wt %) : BrCF ₂ CF ₂ Br (76.5), CF ₂ BrCF ₂ CH ₂ CH ₂ Br (15.7), CF ₂ BrCF ₂ (CH ₂ CH ₂ ) ₂ Br (7.4), and CF ₂ BrCF ₂ (CH ₂ CH ₂ ) ₃ Br (0.35) . Conversion of ethylene was 70%.

EXAMPLE 15

CF2BrCFClBr/CF2=CH2 Telomers with CFp.8 as Initiator

In a reaction similar to Example 14, 104 g (0.38 mol) of CF ₂ BrCFClBr, 4 g of fluorographite CF _. .8 and 20 g (0.31 mol) of CF2=CH ₂ was used. The reaction vessel was shaken at 120°C for 18 hr. The crude product (analyzed by GC and NMR) was mixture of starting bromide (73.4) and telomers (wt-%) CF2BrCFClCH2CF ₂ Br, 16.0; CF ₂ BrCFCl(CH ₂ CF ₂ )2Br, 7.0; CF ₂ BrCFCl (CH2CF ₂ ) 3Br, 2.2;

CF2BrCFCl (CH2CF2) Br, <1. Conversion of CF2BrCFClBr was 28%.

Additional polymerization reactions conducted according to the procedure in Example 4 and using catalysts shown in Examples 16-26, below, are described in Table 1.

EXAMPLE 16 SbFs/CFp. ₂ 5 polymerized tetrafluoroethylene (TFE) in perfluoro-n-hexane. EXAMPLE 17

Polymerization of TFE was initiated by CF _Φ25 i ⁿ perfluoro-n-hexane.

EXAMPLE 18

Pure graphite as a catalyst for TFE polymerization up to 80°C gave a very low conversion to polymer.

EXAMPLE 19 SbF ₅ /CF .8 was used as an initiator for TFE in the presence of water.

EXAMPLE 20 CF .8 copoly erized TFE/CH ₂ =CH ₂ in HFP cyclodimer.

EXAMPLE 21 CFp.8 polymerized TFE without solvent.

EXAMPLE 22 CFi.i copolymerized TFE/CF2=CFOCF3 in HFP cyclodimer. X-ray diffraction shows that CFi.i had no graphitic unsaturation. EXAMPLE 23

CFρ.8 initiated HFP homopolymerization at 250°C and 40,000 psi.

EXAMPLE 24 SbFs on CFρ.25 copolymerized TFE/CF2=CFOCF3 in HFP cyclodimer.

EXAMPLE 25 SbFs on graphite fibers copolymerized TFE/CF2=CFOCF3 in HFP cyclodimer. EXAMPLE 26

High surface area coconut carbon was ineffective as a catalyst for TFE/CF2=CFOCF3 copolymerization at 80°C.

EXAMPLE 27 Coke Intercalated with F ₂ as Initiator A 2.0-g sample of Conoco coke into which 0.3 wt-% of fluorine gas had been intercalated at 25°C was charged to a 240-mL Hastelloy tube along with 50 mL of hexafluoropropene cyclic dimer and 5 g (0.50 mol) of tetrafluoroethylene. Reaction was carried out at 25°C for 4 hr, then 60°C for 8 hr, and finally 200°C for 4 hr. Pressure drop from polymerization of TFE occurred mainly at 25°C. The crude product mixture was pulverized in a blender with 300 mL of methanol, filtered, and the filter cake was then rinsed with 100 mL of methanol and dried for 4 hr at 100°C (0.2 mm) to afford 41.7 g of dark grey polymer. Analysis by TGA found no weight loss to 500°C while DSC showed mp 327.0°C for polytetrafluoroethylene.

EXAMPLE 28 Tetrafluoroethylene/perfluoro(propyl vinyl ether) Copolymer with Fluorinated Graphite Fiber as Initiator A 240-mL Hastelloy tube charged with 5.0 g of graphite fibers fluorinated to the 4.5% F level, 50 mL of hexafluoropropene cyclodimer, 10 g (0.038 mol) of perfluoro(propyl vinyl ether), and 25 g (0.25 mol) of tetrafluoroethylene was heated at 80°C for 16 hr. The crude product was blended with 200 mL of methanol and filtered, and the filter cake was washed twice with 100 mL of methanol. The black solid weighed 5.6 g after drying at 100°C (0.1 mm) . TGA: 9.4% weight loss to 586°C with the curve leveling. DSC: no transitions detected, indicating incorporation of an appreciable percentage of the fluorovinyl ether.

EXAMPLE 29 Polymerization of Methyl Methacrylate with CFp.8 Fluorographite as Initiator A 70-mL heavy-walled glass tube charged under N ₂ with 0.5 g of commercial CF .β and 10 mL of inhibited methyl methacrylate was sealed and heated at 80°C for a total of 12 hr, after which the contents were too viscous to pour out. A sample of polymer was obtained by extraction with ethyl acetate and evaporation of solvent, affording 2.1 g of a stiff, black film.

EXAMPLE 30 CCl ₄ /CH ₂ =CH ₂ Telomers with CFi. s as Initiator

156 g of CCI ₄ , 4 g of fluorinated coke CFi.ps and 6 g of ethylene was used. The reaction vessel was shaken at 150°C. After 16 h, the shaker tube was unloaded and the reaction mixture was filtered. There was recovered 4.4 g of initiator and 148.9 g of mixture (GC data, wt.%) CCI ₄ (84.2), CC1 ₃ CH ₂ CH ₂ C1 (9.12), CC1 ₃ (CH ₂ CH ₂ ) ₂ C1 (6.29), CCI3 (CH ₂ CH ₂ ) 3CI (0.26) .