Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08C—TREATMENT OR CHEMICAL MODIFICATION OF RUBBERS
  • C08C19/00—Chemical modification of rubber
  • C08C19/02—Hydrogenation
• • 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
  • C08F8/00—Chemical modification by after-treatment
  • C08F8/04—Reduction, e.g. hydrogenation

Definitions

• the present invention relates to high-temperature oil-resistant elastomers prepared from butadiene alkenylpyridine copolymers, butadiene aerylate copolymers, and copolymers of butadiene with 1,3-dienes containing fluorine. More particularly, the invention relates to such high-temperature oil-resistant elastomers prepared from the above-mentioned copolymers, wherein the unsaturated olefinic backbone of each of the copolymers as well as the pendant unsaturation derived from the hydrocarbon diene, is hydrogenated to a high degree, which improves the heat resistance of the copolymer without hydrogenation of the polar groups thereof which would lower the oil-resistance of the copolymer.
• Nitrile-butadiene rubber is an oil- resistant elastomer used in automotive applications, but has poor high temperature properties.
• the recommended continuous use temperature is between 100°- 125°C.
• Commercially available hydrogenated NBR (HNBR) addresses the need for a higher use temperature, oil- resistant elastomer having a continuous use temperature up to about 150°C.
• HNBR is mainly a random copolymer of ethylene and acrylonitrile. HNBR compositions that contain up to 40 weight percent bound acrylonitrile and 60 weight percent hydrocarbon segments have high oil resistance and good low temperature properties. Higher acrylonitrile content in the copolymer would further increase oil resistance, but would be detrimental to low temperature properties.
• NBR can be successfully hydrogenated to form HNBR having desirable thermooxidative stability or high heat-resistance, as well as high oil- resistant properties
• NBR must be hydrogenated utilizing a homogeneous rhodium catalyst which is very expensive, thus making the hydrogenated copolymer product economically limiting.
• the economical and efficient process of the present invention cannot be utilized to hydrogenate NBR since the pendant nitrile groups of the copolymer would hydrogenate, thus lowering oil-resistance and also causing cross-linking of the polymer chains making the copolymer product unsuitable for elastomer applications.
• butadiene-alkenylpyridine copolymers, butadiene-acrylate copolymers, and copolymers of butadienes with 1,3-dienes containing fluorine are hydrogenated using the process of the present invention to produce a high-temperature and oil-resistant elastomer, wherein the unsaturated olefinic backbone of each of the copolymers as well as the pendant unsaturation derived from the hydrocarbon diene, is hydrogenated to a high degree which results in the improved heat-resistance of the copolymer, without hydrogenation of the polar groups thereof thereby maintaining the oil-resistance of the copolymer.
• these hydrogenated copolymers of the present invention are produced in an economical manner, making them more desirable than the expensive HNBR copolymers.
• U. S. Patent 3,416,899 (Schiff, December 17, 1968) relates to improved gel compositions useful, as incendiary fuels, as solid fuels for heating, as a fracturing liquid for subterranean formations, and the like.
• this reference relates to the preparation of hydrocarbon gel compositions by hydrogenating a hydrocarbon solution of an unsaturated rubbery polymer in the presence of a catalyst comprising a reducing metal compound and a salt of a Group VIII metal.
• U.S. Patent 3,673,281 (Bronstert et al., June 27, 1972) relates to a process for the hydrogenation of polymers containing double bonds in solution and in the presence of a catalyst complex comprising:
• A a compound of iron, cobalt or nickel
• Polymers of diene hydrocarbons contain double bonds in the backbone. These double bonds may be hydrogenated by conventional processes. Products which are wholly or partly hydrogenated in this way are superior to non-hydrogenated polymers in that they possess improved resistance to aging and are particularly resistant to oxidative degradation. In the case of block copolymers of dienes and vinyl aromatic compounds, in particular, the hydrogenated products also show improved tensile properties and mechanical strength. When only partially hydrogenated, the diene polymers may be vulcanized. Such vulcanizates possess a higher tensile strength and a lower glass temperature than vulcanizates of non-hydrogenated diene polymers.
• U.S. Patent No. 3,625,927 (Yoshimoto et al, December 7, 1971) relates to a catalyst for hydrogenating a high molecular weight polymer having hydrogenatable unsaturated bonds.
• This catalyst is suitable for hydrogenation of the polymer is a viscous solution form and comprises a reaction product of (1) a metal chelate compound of nickel, cobalt, or iron, with (2) an organic metallic reducing agent in said chelate compound.
• the chelating agent is attached to the metal by a pair of nitrogen atoms and an oxygen atom.
• U. S. Patent No. 3,531,450 (Yoshimoto et al, September 29, 1970) relates to a new hydrogenation catalyst consisting of three catalytic components and a process for hydrogenating polymers by the use of said catalyst.
• This three-component catalyst consists of (1) at least one kind of an unsaturated hydrocarbon selected from the group consisting of an olefinically unsaturated hydrocarbon and an acetylenically unsaturated hydrocarbon, (2) at least one kind of an organic compound of the metal selected from the group consisting of nickel, cobalt and iron, and (3) at least one kind of a metal compound reducing agent.
• U. S. Patent 3,766,300 discloses a process for the hydrogenation of copolymers prepared from conjugated dienes and certain copolymerizable polar monomers such as vinyl pyridines, acrylonitriles, and alpha-olefin oxides which comprises an initial step of forming a complex between at least one Lewis acid and the polar portions of the copolymer and thereafter subjecting the complex to hydrogenation. More particularly, this reference is especially con cerned with a process for the hydrogenation of block copolymers derived from these monomers.
• Japanese Patent 13,615 (August 2, 1967; filed February 15, 1963) relates to copolymers of butadiene and vinyl pyridine that were reduced to give waterproof, stable reduced copolymers. These products were useful for coating pills.
• the reduced copolymers were obtained by the catalytic hydrogenation in the presence of Raney nickel catalyst.
• Methyl Vinyl Pyridine relates to quaternization of liquid polymers.
• Copolymers of butadiene and 2-methyl- 5-vinyl pyridine (MVP) react with quaternizing agents to form polymeric salts of the type:
• R is an aliphatic or aromatic radical and X represents halide, alkyl sulfate, or aryl sulfonate groups.
• fluoroela- stomers are synthesized by the copolymerization of fluoro olefins, for example
• the fluoro polymers Due to the saturated backbone and presence of carbon fluorine bonds, the fluoro polymers have high thermo- oxidative stability when compared to their hydrocarbon counterparts.
• the major drawback of these fluoro elastomers is their poor low temperature properties which is reflected in relatively high glass transition tempera tures (Tg).
• Tg glass transition tempera tures
• Nitrile (i.e., butadiene/acrylonitrile copolymer with 40 weight percent acrylonitrile) and hydrogenated nitrile rubber exhibit Tg's of about minus 30°C versus a Tg of minus 20°C for the fluorinated copolymer described above.
• Elastomers derived from the copolymerization of fluorinated olefins with hydrocarbon olefins are also heat resistant due to the saturated backbone in these polymers.
• the lower the fluorine content the lower the heat and oil resistance.
• the glass transition temperature of these elastomers is not significantly improved when compared with the corresponding highly fluorinated counterparts.
• elastomeric homopolymers are obtained.
• Free radical polymerization can occur in a 1,2; 3,4; or 1,4 manner. Polymerization in the latter mode would lead to backbone unsaturation in the polymer, which is detrimental to the thermooxidative stability of the polymer, more so than the pendant unsaturation generated by polymerization in a 1,2- or 1,4- manner.
• Elastomeric polymers are also obtained when the hydrogen atoms of 1,3-butadiene are substituted with fluorine atoms (e.g., polyfluoroprene). However, these polymers also suffer from poor thermooxidative instability due to the presence of backbone unsaturation. Thermooxidative stability is increased in polymers derived from highly fluorinated 1,3-dienes, but these materials tend to be plastics.
• Highly fluorinated 1,3-dienes can be copolymerized in emulsion with 1,3-diene hydrocarbons. Relatively low Tg materials can thus be obtained.
• a copolymer of 1,1,2-trifluorobutadiene with butadiene in a 1 to 1 mole ratio has a Tg of minus 48°C.
• U.S. Patent No. 3,308,175 (Barr, March 7,1967) relates to novel fluorine-substituted dienes, to a method for the preparation thereof, to certain novel intermediates and the preparation thereof, and to certain novel intermediates for the production of homologous fluorine-substituted dienes.
• U.S. Patent No. 3,379,773 (Barr, April 23, 1968) relates to polymeric compositions and to processes for the preparation of those compositions. Copolymers of 1,1,2-trifluorobutadiene-1,3 and the method of preparing the same are described within this reference along with comonomers hexafluorobutadiene-1, 3; 3,4- dichloro-3,4,4-trifluorobutene-1; 2,2,2-trifluoroethyl vinyl ether; vinyl chloride; styrene; 1,1,2-tri- fluorobutene-1; and 1,1,4,4-tetrafluorobutadiene-1,3.
• U.S. Patent 3,562,341 (Tarrant et al, February 9, 1971) relates to incompletely polyfluorinated 1,3-dienes capable of forming crosslinked polymers and having fluorine substituents in at least the 1,1,2position, and to synthesis for their preparation. More particularly, this reference relates to a synthesis for 1,1,2-trifluorobutadiene-1,3 and to the compounds 1,1,2,4,4-pentafluorobutadiene-1,3, and 1,1,2,4,4- pentafluoro-3-methylbutadiene-1,3.
• U.S. Patent 3,607,850 (Smith, September 21, 1971) relates to a method of polymerizing conjugated fluorinated dienes which are rubber-like, flexible at low temperatures, and resistant to mineral oils and other chemicals. More particularly, the reference relates to use of rhodium salts or complexes as cata lysts for the polymerization or copolymerization of conjugated fluorinated dienes to produce high molecular weight elastomers.
• Random copolymer compositions which function as oil-resistant elastomers are prepared by the emulsion polymerization of two monomeric classes.
• the first monomeric class consists of a conjugated diene, or branched conjugated diene, or mixtures thereof, containing from 4 to 8 carbon atoms.
• the second monomeric class is characterized by general Formula I
• R 1 is an alkenyl group containing from about 2 to about 8 carbon atoms
• R 2 is hydrogen or an alkyl group containing from 1 to about 8 carbon atoms.
• the random copolymer so formed is then hydrogenated using a transition metal catalyst and at least one complexing agent.
• R 8 is hydrogen or an alkyl group containing from 1 to about 4 carbon atoms and X is -OOR 9 -ONR 10 R 11 or -OOR 12 OR 9 wherein R 9 is an alkyl group containing from 1 to about 4 carbon atoms, - CH 2 CF 3 , or -CH 2 CF 2 CF 2 H, R 10 and R 11 are alkyl groups independently containing from 1 to about 4 carbon atoms and R 12 is an alkylene group containing from 1 to about 4 carbon atoms.
• Mixtures of this second monomeric class may also be employed.
• the second monomeric class can be replaced with up to about 20 percent by weight of
• R 13 is an alkenyl group containing from about 2 to about 8 carbon atoms and R 14 is hydrogen or an alkyl group containing from 1 to about 8 carbon atoms.
• the random copolymers so formed is then hydrogenated using a transition metal catalyst and at least one complexing agent.
• fluorinated copolymers which function as oil resistant elastomers are prepared by emulsion copolymerization of two monomer classes.
• the first monomer comprises a fluorodiene of the structure
• substituent a is independently hydrogen or fluorine
• R 15 is hydrogen or a fluoro alkyl group containing from 1 to about 4 carbon atoms and containing at least three fluoro atoms, with the proviso that both R 15 groups are not hydrogen
• R 16 and R 17 are independently fluorine, hydrogen or a fluoro alkyl group containing from 1 to about 4 carbon atoms and containing at least three fluorine atoms.
• the second monomer may also comprise a mixture of monomers (a) and (b).
• the copolymer so formed is then hydrogenated using a transitional metal catalyst and a complexing agent and the transitional metal catalyst is deactivated after hydrogenation by using a second complexing agent, in the absence of air.
• FIG. 1 is a graph of the proton magnetic resonance spectrum of the unhydrogenated butadiene/2- vinylpyridine copolymer
• FIG. 2 is a graph of the proton magnetic resonance spectrum of the hydrogenated butadiene/2- vinylpyridine copolymer
• FIG. 3 is a graph of the infrared spectrum of the unhydrogenated butadiene/2-vinylpyridine copolymer
• FIG. 4 is a graph of the infrared spectrum of the hydrogenated butadiene/2-vinylpyridine copolymer
• FIG. 5 is a graph of the proton magnetic resonance spectrum of the hydrogenated butadiene/methyl acrylate copolymer
• FIG. 6 is a graph of the infrared spectrum of the unhydrogenated butadiene/methyl acrylate copolymer
• FIG. 7 is a graph of the infrared spectrum of the hydrogenated butadiene/methyl acrylate copolymer
• FIG. 8 is a graph of the proton magnetic resonance spectrum of the unhydrogenated butadiene/2- methoxyethyl acrylate copolymer
• FIG. 9 is a graph of the proton magnetic resonance spectrum of the hydrogenated butadiene/2- methoxyethyl acrylate copolymer
• FIG. 10 is a graph of the infrared spectrum of the unhydrogenated butadiene/2-methoxyethyl acrylate copolymer
• FIG. 11 is a graph of the infrared spectrum of the hydrogenated butadiene/2-methoxyethyl acrylate copolymer
• FIG. 12 is a graph of the proton magnetic resonance spectrum of the unhydrogenated 1,1,2-trifluorobutadiene/1,3-butadiene copolymer; and FIG. 13 is a graph of the proton magnetic resonance spectrum of the hydrogenated 1,1,2-tri- fluorobutadiene/butadiene copolymer.
• This invention deals with compositions and a method for preparing high temperature, oil-resistant elastomers by the copolymerization of two monomeric classes followed by the hydrogenation of the copolymer.
• Direct polymerization of ethylene with acrylonitrile to give HNBR is not feasible due to the difference in reactivities of the monomers under the copolymerization conditions. This is generally true in the case of copolymerization of ethylene with any polar alpha, beta unsaturated monomer.
• Direct copolymerization of ethylene and polar alpha, beta unsaturated monomers (including acrylonitrile) using transition metal catalysts have been unsuccessful.
• Free radical polymerization can be performed at lower pressure, ca 60 atmospheres, in a solvent using a Lewis acid as the complexing agent for the polar monomer, acrylonitrile.
• a Lewis acid as the complexing agent for the polar monomer, acrylonitrile.
• the low temperature properties are poorer than the corresponding random copolymer.
• tensile strength is reduced in the perfectly alternating copolymer, due to the lack of polyethylene segments which is responsible for the high strength of the random copolymer.
• Conjugated dienes readily copolymerize with polar alpha, beta monomers in emulsion to give high molecular weight copolymers. Subsequent hydrogenation of the backbone unsaturation in these polymers is an alternate route to copolymers of ethylene with polar alpha, beta unsaturated monomers.
• the first monomeric class is a straight chain conjugated diene, a branched chain conjugated diene, or mixtures thereof.
• This diene contains from 4 to 8 carbon atoms.
• straight chain dienes are 1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, 1,4- hexadiene, 1,3-heptadiene, 2,4-heptadiene, 1,3-octadiene, 2,4-octadiene, and 3, 5-octadiene.
• branched chain dienes are isoprene, 2,3-dimethyl-1,3-butadiene, 2-methy1-1,3-hexadiene, 3- methyl-1,3-hexadiene, 2-methyl-2,4-hexadiene, 3-methyl- 2,4-hexadiene, 2,3-dimethyl-1,3-pentadiene, 2,4-dimeth- yl-1,3-pentadiene, 2-ethyl-1,3-pentadiene, and 3-ethyl- 1,3-pentadiene.
• the preferred dienes for the practice of this invention are butadiene and isoprene.
• the second monomeric class is of the general formula:
• the second monomeric class is of the general formula:
• R 1 is an alkenyl group containing from about 2 to about 8 carbon atoms, preferably from about 2 to 6, and most preferably from 2 to about 4 carbon atoms. Particularly, R 1 is vinyl.
• R 2 is hydrogen or an alkyl group containing from 1 to about 8 carbon atoms. When R 2 is an alkyl group, it preferably contains from 1 to about 6 carbon atoms and most preferably from 1 to about 4 carbon atoms. When R 2 is alkyl, a particular group is methyl.
• R 3 is hydrogen or methyl and X is -OOR 4 , -ONR 5 R 6 or - OOR 7 OR 4 wherein R 4 is an alkyl group containing from 1 to about 4 carbon atoms, -CH 2 CF 3 or -CH 2 CF 2 CF 2 H, R 5 and R 6 are alkyl groups independently containing from 1 to about 4 carbon atoms and -OOR 7 OR 4 is an alkylene group containing from 1 to about 4 carbon atoms.
• R 3 is hydrogen or methyl and X is -OOR 4
• some examples of general formula IA are acrylates, methacrylates, fluorinated acrylates or fluorinated methacrylates.
• general formula IA may be tertiary acrylamides or tertiary methacrylamides.
• X is -OOR 7 OR 4
• R 7 is an alkylene group containing from 1 to about 2 carbon atoms
• R 4 is an alkyl group containing from 1 to about 2 carbon atoms.
• at least 3 percent of general formula (IA) is present in the second monomeric class and most preferably at least 7 percent of general formula (IA) is present in the second monomeric class.
• the second monomeric class is of the general formula:
• R 8 is hydrogen or an alkyl group containing from 1 to about 4 carbon atoms and X is -OOR 9 -ONR 10 R 11 or - OOR 12 OR 9 wherein R 9 is an alkyl group containing from 1 to about 4 carbon atoms, -CH 2 CF 3 , or -CH 2 CF 2 CF 2 H, R 10 and R 11 are alkyl groups independently containing from 1 to about 4 carbon atoms and R 12 is an alkylene group containing from 1 to about 4 carbon atoms.
• R 8 is hydrogen or an alkyl group containing from 1 to 2 carbon atoms and most preferably R 8 is hydrogen or methyl.
• R 9 preferably is an alkyl group containing from 1 to 2 carbon atoms, most preferably R 9 is methyl.
• R 10 and R 11 are alkyl groups independently containing from 1 to 2 carbon atoms and most preferably R 10 and R 11 are methyl.
• R 12 is an alkylene group containing from 1 to about 2 carbon atoms and R 9 is an alkyl group containing from 1 to about 2 carbon atoms.
• R 8 is hydrogen or methyl and X is -OOR 9
• some examples of general Formula II are acrylates, methacrylates, fluorinated acrylates, or fluorinated methacrylates.
• R 8 is hydrogen or methyl and X is -ONR 10 R n
• general Formula II may be tertiary acrylamides or tertiary methacrylamides.
• R 8 is hydrogen or methyl and X is -OOR 12 OR 9 general formula I may be alkoxyalkyl acrylates or methacrylates.
• the general Formula II of the second monomeric class can be replaced with up to about 20 percent by weight of general Formula IIA
• R 13 is an alkenyl group containing from about 2 to about 8 carbon atoms and R 14 is hydrogen or an alkyl group containing from about 1 to about 8 carbon atoms.
• R 13 is an alkenyl group containing from about 2 to about 6 carbon atoms, and most preferably from 2 to about 4 carbon atoms.
• R 13 is vinyl.
• R 14 is an alkyl group, it preferably contains from 1 to about 6 carbon atoms and most preferably from 1 to about 4 carbon atoms.
• R 14 is alkyl, a particular group is methyl.
• at least 3 percent of general Formula IIA is present in the second monomeric class and most preferably at least 7 percent of general Formula IIA is present in the second monomeric class.
• the hydrogenated random copolymers of the first two embodiments of this invention have utility as high temperature oil-resistant elastomers.
• the hydrogenated random copolymers of these embodiments may be solids or liquids, depending on molecular weight. These hydrogenated random copolymers serve as thermooxidative- ly stable oil resistant elastomers or as impact modifiers for plastics. Products made from these elastomers find use for seals, gaskets, and hoses.
• the liquid polymers can be used as processing aids and/or modifiers in rubber and plastic compounding.
• Conjugated 1,3-dienes copolymerize readily with alpha, beta unsaturated monomers other than acrylonitrile.
• Examples of two such monomer classes are vinyl pyridine or acrylates. These copolymers, like NBR, are also oil resistant.
• hydrogenation of the polymer backbone together with the pendant unsaturation derived from the hydrocarbon diene of the conjugated diene/vinyl pyridine and conjugated diene/acrylate copolymers is possible with inexpensive homogeneous catalysts based on iron, cobalt or nickel by the process of the present invention.
• high temperature oil resistant elastomer compositions of the present invention can be obtained at a cost lower than that of HNBR.
• the first step in the preparation of an oil- resistant elastomer is in forming a random copolymer of the two monomeric classes.
• the random copolymer is formed by emulsion polymerization.
• the weight ratio of the first monomeric class: the second monomeric class is from about 25-85:75-15, preferably 40-60:60-40, and most preferably 55-60:45-40.
• the random copolymer is made in a conventional manner. That is, the above-noted monomers are added to suitable amounts of water in a polymerization vessel along with one or more conventional ingredients and polymerized.
• the amount of polymerized solids or particles is generally from about 15 percent to about 50 percent with from about 25 to about 35 percent by weight being desired.
• the temperature of polymerization is generally from about 5°C to about 80°C with from about 5°C to about 20°C being preferred. Typically in excess of 60 percent and usually from about 70 percent to about 95 percent conversion is obtained with from about 80 percent to about 85 percent conversion being preferred.
• the polymerization is generally initiated by free radical catalysts which are utilized in conventional amounts.
• catalysts examples include organic peroxides and hydroperoxides such as benzoyl peroxide, dicumyl peroxide, cumene hydroperoxide, paramenthane hydroperoxide, and the like, used alone or with redox systems; diazo compounds such as dimethyl 2,2'-azobisis- obutyrate, and the like; persulfate salts such as sodium, potassium, and ammonium persulfate, used alone or with redox systems; and the use of ultraviolet light with photo-sensitive agents such as benzophenone, triphenylphosphine, organic diazos, and the like.
• organic peroxides and hydroperoxides such as benzoyl peroxide, dicumyl peroxide, cumene hydroperoxide, paramenthane hydroperoxide, and the like, used alone or with redox systems
• diazo compounds such as dimethyl 2,2'-azobisis- obutyrate, and the like
• persulfate salts such as sodium
• anionic emulsifying aids are utilized.
• various conventional anionic surfactants known to the art as well as to the literature are utilized.
• any suitable anionic surfactant can be utilized such as those set forth in McCutcheons, "Detergents and Emulsifiers," 1978, North American Edition, Published by McCutcheon's Division, MC Publishing Corp., Glen Rock, New Jersey, U.S.A., as well as the various subsequent editions thereof, all of which are hereby fully incorporated by reference.
• various conventional soaps or detergents are utilized such as a sodium alkyl sulfate, wherein the alkyl group has from 8 to 22 carbon atoms such as sodium lauryl sulfate, sodium stearyl sulfate, and the like, as well as various sodium alkyl benzene sulfonates, wherein the alkyl group has from 8 to 22 carbon atoms such as sodium dodecyl benzene sulfonate, and the like.
• Other anionic surfactants include sulfo- succinates and disulfonated alkyl benzene derivatives having a total of from 8 to 22 carbon atoms.
• Various phenyl type phosphates can also be utilized.
• anionic surfactants include various fatty acid salts having from 12 to 22 carbon atoms as well as various rosin acid salts wherein the salt portion is generally lithium, sodium, potassium, ammonium, magnesium, and the like.
• the selection of the anionic surfactant generally depends on the pH of the polymerization reaction. Hence, fatty acid salts and rosin acid salts are not utilized at low pH values.
• the amount of the surfactant can vary depend- ing upon the size of random copolymer particles desired, but typically is from about 1 percent to about 6 percent and desirably from about 2 percent to about 3 percent by weight for every 100 parts by weight of the random copolymer forming monomers.
• anionic emulsifying aids are various anionic electrolytes which control particle size by controlling the solubility of the soap.
• Examples of various conventional electrolytes generally include sodium, potassium, or ammonium naphthalene sulfonates.
• Other suitable electrolytes include sodium sulfate, sodium carbonate, sodium chloride, potassium carbonate, sodium phosphate, and the like.
• the amount of electrolyte is generally from about 0.1 to about 1.0 parts by weight and preferably from about 0.2 to about 0.5 parts by weight for every 100 parts by weight of the random copolymer forming monomers.
• Molecular weight modifiers are also utilized to maintain the molecular weight within desirable limits as otherwise the viscosity of the polymer would be exceedingly high for subsequent handling, processing, and the like.
• known conventional molecular weight modifiers can be utilized such as various mercaptans which have from about 8 to about 22 carbon atoms, generally in the form of an alkyl group.
• Various sulfide compounds can also be utilized such as diisopro- pylxanthogendisulfide and di-sec-butylxanthogendisul- fide.
• the amount of the molecular modifiers is generally an effective amount such that the Mooney viscosity, that is ML 4 @ 100°C is from about 10 to about 120 and desirably from about 20 to about 80.
• Yet another conventional emulsion latex additive is various short stop agents which are added generally to stop the polymerization and to tie up and react with residual catalysts.
• the amount of the short stop agents is from about 0.05 to about 1.0 parts by weight per 100 parts by weight of said random copolymer forming monomers.
• specific short stop agents include hydroxyl ammonium sulfate, hydroquinone and derivatives thereof, e.g., ditertiaryamylhydroquinone, various carbamate salts such as sodium diethyldithio- carbamate, various hydroxyl amine salts, and the like.
• antioxidants can be added and such are known to the art as well as to the literature including various phenolic type antioxidants such as di-tert-butyl-paracresol, various diphenylamine antioxidants such as octylated diphenylamine, various phosphite antioxidants such as trisnonyl phenyl phosphite, and the like.
• a cationic coagulant polymer is utilized to coagulate the anionic emulsifying aids such as the various anionic surfactants and the various anionic electrolytes utilized.
• Polymeric cationic type coagulants are utilized according to the present invention inasmuch as they have a positive site which generally reacts with the negative or anionic site of the surfactant, electrolyte, etc., and thereby neutralize the same and render it innocuous. That is, according to the concepts of the present invention, the anionic emulsifying aids are not physically removed but rather are chemically reacted with a cationic polymeric coagulant to form an adduct which is generally dispersed throughout the random copolymer particle.
• cationic polymeric coagulants Large stoichiometrically equivalent amounts of cationic polymeric coagulants are utilized. That is, large weight equivalents are required in order to yield a random copolymer having improved properties. Generally, from about 0.75 to about 1.5 weight equivalents, desirably from about 0.85 to about 1.25, and preferably from about 0.95 to about 1.05 weight equivalents of the cationic polymeric coagulant is utilized for every weight equivalent of said anionic emulsifying aids. Equivalent weight amounts less than those set forth herein do not result in effective neutralization, tying up, or negate the effect which the various anionic emulsifying aids have upon the properties of the dried rubber particles.
• the cationic polymeric coagulants utilized in the present invention generally contain a tetravalent nitrogen and are sometimes referred to as polyquats. This invention Cationicity of the quaternary nitrogen is generally independent of pH, although other parts of the polymer molecule may exhibit sensitivity to pH such as hydrolysis of ester linkages.
• cationic polymers are prepared either by quaternization of poly(alkylene polyamines),poly(hydroxyalkylene polyamines), or poly(carbonylalkylene polyamine) with alkyl halides or sulfates, or by step-growth polymerization from dialkylamines, tetraalkyl amines, or derivatives thereof, with suitable bifunctional alkylating agents, and with or without small amounts of polyfunctional primary amines (such as ammonia, ethylene diamines, and others) for molecular weight enhancement.
• suitable bifunctional alkylating agents such as ammonia, ethylene diamines, and others
• Polyamines produced from ammonia and ethylene dichloride, quater- nized with methyl chloride, and polyquaternaries produced directly from dimethylamine and 1-chloro-2,3-epoxypr- opane are generally of commercial significance.
• Epichl- orohydrin reacts with ammonia and primary, secondary, or polyfunctional amines to form polyamines or polyquats.
• the polyamines can be subsequently quaternized to yield a cationic polymeric coagulant of the present invention.
• polymeric cationic coagulants examples include poly (2-hydroxypropyl-1-N- methylammonium chloride), poly (2-hydroxypropyl-1,N,N- dimethylammonium chloride), poly(diallyldimethylammonium chloride), poly(N,N-dimethylaminoethyl methacrylate) quaternized, and a quaternized polymer of epichlorohydrin and a dialkylamine wherein the alkyl group has from 1 to 5 carbon atoms with methyl being preferred.
• the cationic polymeric coagulants utilized in the first two embodiments of the present invention generally have a molecular weight of from about 1,000 to about 10,000,000.
• the cationic polymeric coagulant treated random copolymer latex generally results in a. slurry of rubber crumbs in a clear aqueous liquid.
• the crumbs contain the various anionic emulsifying aids physically incorporated therein.
• Such crumbs can be separated in any conventional manner as by filtering. Inasmuch as the anionic emulsifying aids have been rendered innocuous, multiple washing steps or other expensive, tedious process steps such as solvent extraction are not utilized.
• the random copolymers of the first two embodiments of the present invention once dried as by conventional means, have improved properties such as good water resistance, good adhesion properties, non-interference with cure systems when cured, reduce fouling of molds during the manufacture of parts, improved electrical insulating properties, and the like.
• Such polymers can accordingly be utilized as adhesives, that is polymeric adhesives, binders, films, e.g., electrical insulating films, coatings such as for electrical circuit boards along with other conventional coating additives and fillers known to the art and to the literature, and the like.
• Suitable adhesive uses include metal-to-metal adhesion, metal-to-fabric ad hesion, metal-to-plastic adhesion, and the like.
• the polymers of the first two embodiments of this invention have utility in the automotive area such as in hoses, gaskets, seals, and timing belts.
• the random copolymers can be prepared with a mercaptan chain transfer agent composition comprising (a) at least one mercaptan chain transfer agent and (b) at least one non-polymerizable material which is miscible with the mercaptan chain transfer agent.
• Suitable mercaptans include water soluble mercaptans such as 2- mercaptoethanol, 3-mercaptopropanol, thiopropyleneglycol, thioglycerine, thioglycolic acid, thiohydracrylic acid, thiolactic acid, and thiomalic acid, and the like.
• Suitable non-water soluble mercaptans include isooctyl thioglycolate, n-butyl 3-mercaptopropionate, n-butylthioglycolate, glycol dimercaptoacetate, triraethylolpro- pane trithioglycolate, alkyl mercaptans, and the like.
• the preferred mercaptans are 2-raercaptoethanol and tdodecylmercaptan, however, any chain transfer agent having a mercapto (-SH) group would be acceptable.
• the chain transfer composition in addition to the mercaptan, may contain at least one non-polymerizable material which is miscible with the mercaptan and is substantially insoluble in water.
• non-polymerizable as used herein means that the material does not form a part of the random copolymer chain in the sense that a traditional comonomer would form.
• the non-polymerizable material may, in some cases, graft polymerize onto the random copolymer chain but this is not normally considered a copolymer.
• substantially insoluble in water as used in this specification means that the material has less than 5 percent solubility in water.
• the non-polymerizable material may be a monomer, oligomer or a polymer.
• Suitable non- polymerizable materials include dioctyl phthalate, low molecular weight poly (caprolactone), polysilicones, esters of glycerols, polyesters, water insoluble esters of fatty acids with -OH terminated polyoxyethylene and polyoxypropylene, esters of polyols, esters of monoacids and polyacids, esters of organic polyphosphates, phenyl ethers, ethoxylated alkylphenols, sorbitan monostearate and sorbitan monooleate and other sorbitol esters of fatty acids.
• the choice of material is not critical as long as the material is non-polymerizable with the monomers and is substantially insoluble in water.
• the chain transfer composition must contain at least enough non-polymerizable material to encapsulate the mercaptan chain transfer agent. This amount varies according to the type and amount of chain transfer agent used. Usually, the chain transfer composition must contain at least an equal amount in weight of non- polymerizable material as chain transfer agent in order to encapsulate or host the chain transfer agent. Preferably, the composition contains at least twice as much weight of non-polymerizable material as chain transfer agent. Other non-essential ingredients may be used in the chain transfer compositions of this invention but are not preferred.
• the chain transfer compositions are formed by mixing the two essential ingredients together.
• the method used to mix the ingredients is not critical and may be any of the known methods used by those skilled in the art.
• the ingredients may even be charged to the polymerization reactor and mixed before adding the other polymerization ingredients but is preferably mixed outside the reactor.
• the non-polymerizable material serves as a host material for the chain transfer agent. This procedure surprisingly eliminates the adverse effects of 2-mercaptoethanol on colloidal stability. It is believed that the non-polymerizable material averts the adverse effect of 2-mercaptoethanol on colloidal stability via encapsulation, complexation or interaction and, thus, allows relatively high levels of 2-mercap- toethanol to be introduced to the reaction medium prior to the start of polymerization.
• the term "encapsulation" as used herein is not intended as the traditional meaning of encapsulation which is to coat or contain and the result is a heterogeneous system.
• the chain trans- fer composition of this invention is homogeneous.
• the level of chain transfer composition used to make the random copolymer will be described in terms of the level of mercaptan in the composition.
• the level of mercaptan used is greater than 0.03 part by weight per 100 parts by weight of diene monomer.
• the preferred levels of mercaptan range from about 0.03 to about 5.00 parts by weight per 100 parts of monomer, and, preferably, from 0.10 to 1.50 parts.
• chain transfer agent If less than 0.25 part by weight of chain transfer agent is used, then all of the chain transfer agent will be added in the form of the chain transfer composition before the beginning of polymerization. If more than 0.25 part is used, then at least 0.25 part will be added in the form of the chain transfer composition before the beginning of polymerization and the remainder may be added later. To gain the most efficiency of the chain transfer agent, no more than 1.5 parts by weight should be added before the start of polymerization. For best results, at least 50 percent of the chain transfer agent, preferably 100 percent, is added to the polymerization medium prior to the start of polymerization. Any amount not added at the start and not encapsulated should be added after the polymerization has reached about 10 percent conversion to maintain colloidal stability. Except for the use of the chain transfer composition, the polymerization is much the same as in any conventional polymerization of a diene monomer in an aqueous medium.
• X represents hydrogen or -SH
• Y represents an alkylene group having 1 to 6 carbon atoms
• ra and n each represents a number in the range of 1 to 10.
• a preferred group of ether linkage chain- transfer agents includes mercapto organic compounds that have the structural formula
• X represents hydrogen or -SH
• Y' represents an alkylene group having 2 to 4 carbon atoms
• m' and n' each represents a number in the range of 2 to 4.
• ether linkage chaintransfer agents that can be used in the practice of this invention are the following compounds:
• ether linkage chain- transfer agents are 2-mercaptoethyl ethyl ether and bis- (2-mercaptoethyl) ether.
• the amount of the ether linkage chain-transfer agent that is used in the polymerization reaction is that which will provide a polymer having the desired molecular weight or degree of polymerization. In most cases from 0.01 percent to 2 percent by weight, based on the weight of the monomer component, is used. When a low molecular weight product that has a relative viscosity in the range of 1.20 to 1.60 is desired, the amount of chain transfer agent used is preferably in the range of 0.25 percent to 1.75 percent by weight, based on the weight of the monomer. Amounts in the range of 0.05 percent to 0.15 by weight, based on the weight of the monomer, are preferably used to produce polymers having high molecular weights.
• the random copolymers obtained in the first two embodiments of the present invention generally have a weight average molecular weight of from about 20,000 to about 1,000,000; desirably from about 200,000 to about 750,000; and preferably from about 400,000 to about 500,000.
• Table I shows the preparation of a random copolymer of butadiene and 2-vinylpyridine.
• Items 1 through 9 are initially charged into a 15 gallon reactor under nitrogen and cooled to 5°C. Polymerization is initiated by adding items 10 through 12. These three items promote peroxide breakdown thereby generating initiator radicals. The conversion is monitored by measuring total solids content every hour. At 35 percent conversion, the additional items 1 through 5 are added. After 20 hours, at 5°C, 80 percent conversion is obtained and the reaction is terminated by adding item 13. After removal of volatiles, the latex is coagulated in hot water (70°C) containing 1.5 weight percent of aluminum sulfate to form a crumb. The crumb is filtered, washed with water and dried in air at 100°C for 4 hours.
• Examples 2 through 5 essentially follow the procedure of Example 1 except for the monomers and level of monomers employed. Table II outlines Examples 2 through 5.
• the random copolymer obtained has a high cis- trans-1,4 microstructure rather than 1,2 and/or 3,4 microstructure (depending upon the diene).
• the combined mole percent of cis-trans 1,4-microstructure to vinyl microstructure has been determined to be 3.7:1 by proton magnetic resonance when the copolymers have a weight ratio of 60 percent butadiene to 40 percent 2-vinylpyridine by weight.
• the cis and trans microstructure get hydrogenated to linear polyethylene segments which are responsible for the improved mechanical properties of the elastomer due to stretch crystallinity (A.H. Weinstein, Rubber Chemical Technology 57, 203 (1984)).
• Example 6 (second embodiment)
• Table III shows the preparation of a random copolymer of butadiene and methyl acrylate.
• Items 1 through 9 are initially charged into a 15 gallon reactor under nitrogen and cooled to 5°C. Polymerization is initiated by adding items 10 through 12. These three items promote peroxide breakdown thereby generat ing initiator radicals. The conversion is monitored by measuring total solids content every hour. At 35 percent conversion, the additional items 1 through 5 are added. After 20 hours, at 5°C, 80 percent conversion is obtained and the reaction is terminated by adding item 13. After removal of volatiles, the latex is coagulated in hot water (70°C) containing 1.5 weight percent of aluminum sulfate to form a crumb. The crumb is filtered, washed with water and dried in air at 100°C for 4 hours.
• Examples 7 through 10 essentially follow the procedure of Example 6 except for the monomers and level of monomers employed. Table IV outlines Examples 7 through 10.
• the random copolymer obtained has a high cistrans 1,4 microstructure rather than 1,2 and/or 3,4 microstructure (depending upon the diene).
• the combined mole percent of cis-trans 1,4-microstructure to vinyl microstructure has been determined to be 3.7:1 by proton magnetic resonance when the copolymers have a weight ratio of 50 percent butadiene to 50 percent methyl acrylate.
• the cis and trans microstructure get hydrogenated to linear polyethylene segments which are responsible for the improved mechanical properties of the elastomer due to stretch crystallinity (A.H. Weinstein, Rubber Chemical Technology 57, 203 (1984).
• the random copolymer once obtained in either of the first two embodiments of the invention described above is then subjected to hydrogenation in the presence of a transition metal catalyst and trialkylaluminum catalyst in the presence of at least one complexing agent and further in the absence of BF 3 or BF 3 etherate.
• a homogeneous or a heterogeneous catalyst may be used for the hydrogenation although a homogeneous catalyst is preferred. Since a homogeneous catalyst dissolves in solution, good contact is obtained with the random copolymer.
• the homogeneous catalysts are transition metal catalysts of either iron, cobalt, or nickel. These metals are present as halides, acetates, or acetylacetonates.
• transition metal salts that are soluble in the organic solvents used to dissolve the polymeric substrates. These salts then yield a homogeneous zero or low valent metallic species, which can be transformed efficiently under hydrogen into a metal hydride species that is the active hydrogenation catalyst.
• the reduction of insoluble transition metal salts cause the reduced metallic species to encapsulate the metal salt substrate, thus preventing complete reduction. Transformation of this heterogeneous reaction product to the active metal hydride is also then inefficient.
• soluble transition metal salts are preferred such as the octoates, neodecanoates, or stearates of cobalt or nickel.
• the least hygroscopic of the above- mentioned salts namely the neodecanoates (due to the bulky hydrophobic groups surrounding the metal ion), are most preferred as water is detrimental to the formation of an active hydrogenation catalyst.
• Other homogeneous catalysts that can be employed are palladium, platinum or rhodium present as tetrakistriphenylphosphine palladium (0), tetrakistriphenylphosphine platinum (0) or tristriphenylphosphinerhodium chloride.
• catalysts based on, for example, reduced cobalt salts are inexpensive compared to rhodium or palladium, but are only suitable for the hydrogenation of hydrocarbon polymers, e.g., a nickel catalyst is commercially used in the hydrogenation of Krayton, a triblock butadiene-styrene-butadiene copolymer. Hydrogenation of the polymer backbone of NBR is not possible using these catalysts, as the nitrile group in NBR acts as a catalyst poison, and, in some cases is itself reduced.
• HNBR is commercially synthesized by the hydrogenation of NBR in solution.
• the relatively high cost of HNBR compared to NBR is partly due to the solution hydrogenation process, the major contribution to cost being the catalyst (rhodium or palladium).
• the transition metal catalyst is employed with trialkylaluminum compounds, wherein the alkyl group contains from 1 to about 4 carbon atoms, which functions as a reducing agent.
• Other reducing agents that can be employed are dialkyl aluminum hydride, the dialkyl aluminum alkoxides of 1 to 4 carbon atoms, sodium borohydride, and lithium aluminum hydride.
• other reduc- tants are alkyl lithium, dialkyl magnesium, and alkyl magnesium halide wherein the alkyl groups are from 1 to 4 carbon atoms, and the halide is chloride or bromide.
• the mole ratio of transition metal catalyst: reducing agent is usually from 1:10, preferably 1:6, and most preferably from 1:4.
• the transition metal catalyst complexes with at least one complexing agent. Without the complexing agent, addition of the catalyst to the polymer solution causes gelation. This is due to crosslinking of the high molecular weight copolymer caused by complexing of the polar groups with the transition metal and metallic species from the reductant employed in catalyst formation.
• the complexation is an equilibrium process wherein the catalyst can be released into solution by the action of the solvent.
• high molecular weight copolymers only one or two crosslinks per 200-300 monomer units are needed to form a gel or the like.
• a gelled polymer is difficult to hydrogenate to a high degree due to reduced catalyst mobility and further due to inefficient contact between hydrogen, the catalyst, and the sites of unsaturation derived from the copolymerized hydrocarbon diene. Also, a partially crosslinked polymer results wherein the polar group may undergo partial hydrogenation (see for example,
• the complexing agents complex with the catalyst in order to prevent the catalyst from excessively bonding to the pyridine rings in the first embodiment of the invention or to the ester functionalities in the second embodiment.
• catalyst mobility is improved.
• the complexing agent allows the catalyst to. break away from the polar groups of the polymer and to travel to the less polar sites of unsaturation where hydrogenation should occur. These sites of unsaturation compete efficiently enough for the catalyst (in comparison to the catalyst complexing agent) in order to allow hydrogenation to proceed.
• the desired degree of hydrogenation of the copolymers produced in the first two embodiments of the present invention is greater than about 80 percent; desirably greater than about 85 percent; and preferably greater than 95 percent hydrogenation of the unsaturation derived from the copolymerized hydrocarbon diene.
• the amount of complexing agent employed is related to the relatively low catalyst level. Generally, the mole ratio of catalyst: complexing agent is from 1:10, preferably 1:8; and most preferably 1:6.
• the complexing agents for the catalysts are hexamethylphosphoric triamide, tetramethylethylenediamine, phosphines of the general formula (R 23 ) 3 P, phosphites of the general formula (R 23 O) 3 P wherein R 23 is an alkyl group containing from 1 to about 6 carbon atoms, a phenyl group or a substituted aromatic group wherein the substituent is an alkyl group containing from 1 to about 2 carbon atoms such as o- tolyl.
• Solvents for the hydrogenation are well known in the art.
• An exemplary list of solvents are xylenes, toluenes, anisole, dioxane, tetrahydrofuran, hydrocarbons such as hexanes, heptanes, and octanes and chlorinated hydrocarbons such as chlorobenzene and tetrachloroethane, tri-substituted amines such as triethylamine and tetrame- thylethylene diamine.
• the temperature of hydrogenation is generally from about 25°C to about 150°C with from about 25°C to about 50°C being preferred.
• the second complexing agents are weak. organic acids containing from 1 to about 4 carbon atoms such as formic acid, acetic acid, and propionic acid; diacids containing from 2 to about 6 carbon atoms such as oxalic acid, maloni ⁇ acid, succinic acid, glutaric acid, and adipic acid and also sodium or potassium salts of the above mono- or diacids; trisodium ethylenediaminete- traacetate; amino acids of 1 to about 4 carbon atoms such as glycine, alanine, alphaglutaric acid, betaglutaric acid, and gammaglutaric acid; citric acid; pyridine or substituted pyridine wherein the substituent contains 1 to 2 carbon atoms; pyridine carboxylic acids such as nicotinic acid and the corresponding sodium or potassium salts; alkyl or aromatic nitriles containing from 1 to 6 carbon atoms; substituted ureas or thioureas such as N
• Example 11 Under nitrogen, 100 grams of the product of Example 1 was dissolved in several portions in one-half gallon of dry tetrahydrofuran in a one gallon high pressure reactor equipped with a paddle stirrer. The copolymer was completely dissolved in about four hours. Preparation of the hydrogenation catalyst solution.
• the hydrogenation catalyst was then added slowly to the stirred copolymer solution under nitrogen followed by the introduction of hydrogen (500 psi). Periodically, the reactor was repressurized to 500 psi in order to compensate for hydrogen uptake by the polymer. When hydrogen uptake at room temperature ceased, the polymer solution was heated to 50°C and the hydrogen pressure increased to 1000 psi. Again, repressurization was continued to compensate for hydrogen uptake by the polymer. After a total time of about six hours, hydrogen uptake stopped. The polymer solution was then cooled to room temperature. Excess hydrogen was vented and replaced with a nitrogen blanket.
• the hydrogenated random copolymer of Example 11 is compounded and evaluated in a side-by-side comparison with a nitrile rubber available from Nippon/Zeon having 36 weight percent acrylonitrile.
• the control Example 14 and the Invention Example 15 are both cured with peroxide.
• Example 11 A sample of hydrogenated butadiene/2-vinyl- pyridine copolymer was made as in Example 11, except using cobalt (II) octoate instead of cobalt (II) neodecanoate as the transition metal catalyst component.
• Formula A u represents the unhydrogenated starting material, and formula A h the hydrogenated product.
• H a proton (area of H a , H b , H c protons - area of H c proton) /2.
• the area of the H c proton and one of the H d protons are equal.
• the copolymer of Formula A h was hydrogenated to 97.8 percent by weight.
• the infrared spectrum of the unhydrogenated butadiene/2-vinylpyridine copolymer is compared with the hydrogenated butadiene/2-vinylpyridine copolymer of Example 11 in Figs. 3 and 4 respectively, and indicates for the hydrogenated polymer the absence of absorptions at 970 and 915 cm -1 which ordinarily result from the olefinic carbon-hydrogen out-of-plane bend (trans 1,4 copolymerized and 1,2 copolymerized butadiene, respectively).
• the backbone and pendant unsaturation have been completely or 100 percent saturated, and only the vinylpyridine group of the hydrogenated copolymer remains unsaturated, which is desirable.
• the characteristic absorption (1590-1430 cm- 1 ) due to the pyridine ring remains unaffected by the hydrogenation process as shown in Figs. 3 and 4.
• the polar character of the copolymer, and hence the oil- resistance is retained in the hydrogenated copolymer.
• the hydrogenated polymer of Example 11 was analyzed for cobalt by ashing the sample, solubilization of the metals in the ashed sample with acid, and measuring the metal concentration by atomic absorption.
• the cobalt concentration was found to be 118 ppm.
• aqueous HCl desirably from about 0.1 to about 2.0 percent, preferably from about 0.25 to about 1.0 percent, and most preferably about 0.45 percent. It is understood that inorganic acids other than HCl, such as nitric acid or sulfuric acid at the same dilute weight percent levels, could also be utilized with similar results.
• Example 6 was dissolved in several portions in one-half gallon of dry tetrahydrofuran in a one-gallon high pressure reactor equipped with a paddle stirrer. The copolymer was completely dissolved in about four hours.
• the hydrogenation catalyst was then added slowly to the stirred copolymer solution under nitrogen followed by the introduction of hydrogen (500 psi). Periodically, the reactor was repressurized to 500 psi in order to compensate for hydrogen uptake by the polymer. When hydrogen uptake at room temperature ceased, the polymer solution was heated to 50°C and the hydrogen pressure increased to 1000 psi. Again, repressurization was continued to compensate for hydrogen uptake by the polymer. After a total time of about six hours, hydrogen uptake stopped. The polymer solution was then cooled to room temperature. Excess hydrogen was vented and replaced with a nitrogen blanket.
• Fig. 5 indicates only a trace of absorption in the olefinic proton region (5-6ppm). Hence, the copolymer is essentially 100 percent hydrogenated.
• the starting material can be represented by formula B u and the hydrogenated material is represented by formula B h .
• the molecular weight of copolymerized methyl acrylate is 86 and that of the hydrogenated butadiene segments is 56.
• the bands at 970 and 915 cm -1 in the starting material are completely absent in that of the product.
• the absorption at 970 cm -1 originates from the olefinic carbon-hydrogen out-of-plane bend due to the trans 1,4 copolymerized butadiene unit, and that at 915 cm -1 from the carbon-hydrogen out-of-plane bend due to the butadiene units copolymerized in a 1,2 fashion.
• Example 17 This is a repeat of Example 16 except that the acetic acid-pyridine solution is added to the hydrogenated polymer in the presence of air rather than under anaerobic conditions.
• 16 and 17 are compounded with plasticizer, processing aids, amine anti-oxidant, curing agents and sulfur donors. These examples are evaluated as Examples 18 and 19, respectively in Table VII.
• a butadiene/2-methoxyethyl acrylate copolymer was synthesized as per Example 6, starting with 40 parts of butadiene and 60 parts of 2-methyoxyethyl acrylate.
• the isolated rubber exhibited a glass transition temperature of -60°C and a Mooney viscosity of 37
• the polymer was hydrogenated and isolated as described in Example 16, except for the use of cobalt (II) octoate as the transition metal component for catalyst formation instead of cobalt (II) neodecanoate.
• Formulas C u and C h represent the starting material and product, respectively.
• H d proton is represented by an area of 7.66/2 or 3.83.
• Residual moles of butadiene copolymerized in a 1,4 fashion is represented by an area of 0.63/2 or 0.31.
• Area representing moles of copolymerized 2- methoxyethyl acrylate is (4.65+11.72)/7 or 2.34.
• Area representing the moles of hydrogenated butadiene is 67.55/8 or 8.44.
• the butadiene/methoxyethyl acrylate copolymer is hydrogenated to 97.8 percent by weight of the copolymer.
• the molecular weight of copolymerized butadiene is 54, that of the hydrogenated butadiene segment 56, and that of copolymerized 2-methoxyethyl acrylate 114.
• the hydrogenation catalyst formed from cobalt neodecanoate is more efficient than that formed from cobalt octoate as the transition metal component. This is related to the higher water content in the commercially available cobalt octoate solution (1.1 wt percent) than in cobalt neodecanoate (0.32 wt. percent).
• fluorine containing 1,3-dienes are copolymerized with hydrocarbon 1,3-dienes. Glass transition temperature and oil resistance are dependent upon the fluorine content. More specifically, the polar groups in the copolymer contribute to polymer oil-resistance while maintaining polymer thermooxidative stability.
• the unsaturation of copolymerized fluorinated 1,3- dienes is unaffected by the hydrogenation process.
• Thermooxidative stability is improved greatly by removal of carbon/carbon unsaturation derived from the hydrocarbon diene in the polymer, through hydrogenation.
• thermooxidatively stable oil-resistant polymers with good low temperature properties are obtained.
• 1,3-butadiene as a comonomer yields strong elastomers due to stretch crystallizable polyethylene segments in the polymer that are formed by the hydrogenation process.
• the use of the relatively inexpensive hydrocarbonbased dienes help lower raw material costs.
• a hydrogenated copolymer is prepared from at least two monomers.
• a copolymer is formed by emulsion polymerization and then hydrogenated to obtain a thermo- oxidatively stable composition.
• the copolymer is prepared from two monomer classes.
• the first monomer comprises a fluorodiene of the structure
• substituent a is independently hydrogen or fluorine
• R 15 is hydrogen or a fluoro alkyl group containing from 1 to about 4 carbon atoms and containing at least three fluoro atoms, with the proviso that both R 15 groups are not hydrogen
• R 16 and R 17 are independently fluorine, hydrogen or a fluoro alkyl group containing from 1 to about 4 carbon atoms and containing at least three fluorine atoms.
• the second monomer may also comprise a mixture of monomers (a) and (b).
• the first monomer is a fluorodiene.
• fluoroalkyl as used herein signifies that hydrogens of an alkyl group are replaced with fluorine.
• Structural examples of fluoro alkyl groups are: -CF 3 , -CH 2 CF 3 , -CHFCHF 2 , -CF 2 CH 2 F, -CHFCF 3 ,
• the fluoro alkyl group contains from 1 to 2 carbon atoms and has at least three fluoro atoms.
• Preferable fluoro alkyl groups are -CF 3 , -CH 2 CF 3 , -CF 2 CF 3 or -CF 2 CHF 2 .
• the most preferable fluoro alkyl group is -CF 3 .
• the second monomer is (a) a straight chain conjugated diene, a branched conjugated diene, or mixtures thereof containing from 4 to 8 carbon atoms.
• straight chain dienes are 1,3-butadiene, 1,3-pentadiene, 1,3- hexadiene, 1,4-hexadiene, 1,3-heptadiene, 2,4-heptadiene, 1,3-octadiene, 2,4-octadiene, and 3,5-octadiene.
• branched chain dienes are isoprene, 2, 3-dimethyl-1,3-butadiene, 2-methyl-1,3- hexadiene, 3-methyl-1,3-hexadiene, 2-methyl-2,4-hexa- diene, 3-methyl-2,4-hexadiene, 2,3-dimethyl-1,3-pentadiene, 2,4-dimethyl-1,3-pentadiene, 2-ethyl-1,3- pentadiene, and 3-ethyl-1,3-pentadiene.
• the preferred dienes for the practice of the invention are butadiene and isoprene.
• R 18 is hydrogen or an alkyl group containing from 1 to 2 carbon atoms and most preferably R 18 is hydrogen or methyl.
• R 19 preferably is an alkyl group containing from 1 to 2 carbon atoms, most preferably R 19 is methyl.
• R 20 and R 21 are alkyl groups independently containing from 1 to 2 carbon atoms and most preferably R 20 and R 21 are methyl.
• R 22 is an alkylene group containing from 1 to about 2 carbon atoms and R 19 is an alkyl group containing from 1 to about 2 carbon atoms.
• R 18 is hydrogen or methyl and X is -CONR 20 R 21
• R 18 is hydrogen or methyl and X is -COOR 22 OR 19
• the hydrogenated copolymers of the third embodiment of the present invention also have utility as high temperature oil-resistant elastomers.
• the hydroge- nated copolymers of this third embodiment may be solids or liquids, depending on molecular weight. These hydrogenated copolymers serve as thermooxidatively stable oil-resistant elastomers or as impact modifiers for plastics. Products made from these elastomers find use for seals, gaskets, and hoses.
• the liquid polymers can be used as processing aids and/or modifiers in rubber and plastic compounding.
• the first step in the preparation of an oil- resistant elastomer is in forming a copolymer.
• the copolymer is formed by emulsion polymerization.
• the mole ratio of the first monomer: second monomer is from about 4:3, preferably 2:3, and most preferably 1:1.
• the copolymer is made in a conventional manner. That is, the above-noted monomers are added to suitable amounts of water in a polymerization vessel along with one or more conventional ingredients and polymerized.
• the amount of polymerized solids or particles is generally from about 15 percent to about 50 percent with from about 25 to about 35 percent by weight being desired.
• the temperature of polymerization is generally from about 5°C to about 80°C with from about
• the copolymerization is generally initiated by free radical catalysts which are utilized in conventional amounts, with examples of such catalysts being those discussed above with regard to the first two embodiments of the present invention, which discussion is hereby fully incorporated by reference.
• Molecular weight modifiers are also utilized to maintain the molecular weight within desirable limits as otherwise the viscosity of the polymer would be exceedingly high for subsequent handling, processing, and the like.
• known conventional molecular weight modifiers can be utilized such as are discussed above with respect to the first two embodiments of the present invention, which discussion is hereby fully incorporated by reference.
• Yet another conventional emulsion latex additive is various short stop agents which are added generally to stop the polymerization and to tie up and react with residual catalysts. Such agents are discussed above with respect to the first two embodiments of the invention and such discussion is hereby fully incorporated by reference.
• a cationic coagulant polymer also is utilized in the third embodiment of the invention to coagulate the anionic emulsifying aids such as the various anionic surfactants and the various anionic electrolytes utilized, and the discussion thereof with respect to the first two embodiments of the present invention is hereby fully incorporated by reference.
• the cationic polymeric coagulant treated copolymer latex of the third embodiment of the invention generally results in a slurry of rubber crumbs in a clear aqueous liquid.
• the crumbs contain the various anionic emulsifying aids physically incorporated therein.
• Such crumbs can be separated in any conventional manner as by filtering. Inasmuch as the anionic emulsifying aids have been rendered innocuous, multiple washing steps or other expensive, tedious process steps such as solvent extraction are not utilized.
• the copolymer of the third embodiment of the present invention once dried as by conventional means, has improved properties such as good water resistance, good adhesion properties, non-interference with cure systems when cured, reduce fouling of molds during the manufacture of parts, improved electrical insulating properties, and the like.
• Such copolymers can accordingly be utilized as adhesives, that is polymeric adhesives, binders, films, e.g., electrical insulating films, coatings such as for electrical circuit boards along with other conventional coating additives and fillers known to the art and to the literature, and the like.
• Suitable adhesive uses include metal-to-metal adhesion, metal-to-fabric adhesion, metal-to-plastic adhesion, and the like.
• the polymers of the third embodiment of this invention have utility in the automotive area such as in hoses, gaskets, seals, and timing belts.
• the copolymer can be prepared with a mercaptan chain transfer agent composition comprising (a) at least one mercaptan chain transfer agent and optionally (b) at least one non-polymerizable material which is miscible with the mercaptan chain transfer agent.
• a mercaptan chain transfer agent composition comprising (a) at least one mercaptan chain transfer agent and optionally (b) at least one non-polymerizable material which is miscible with the mercaptan chain transfer agent.
• Suitable mercaptans include those discussed above with respect to the first two embodiments of the present invention, which discussion is hereby fully incorporated by reference.
• the chain transfer composition may comprise, in addition to the mercaptan, at least one non-polymer izable material which is raiscible with the mercaptan and is substantially insoluble in water, and the discussion thereof with regard to the first two embodiments of the present invention also is hereby fully incorporated by reference.
• the molecular weight of the copolymers of the third embodiment of the present invention have a weight average molecular weight of from about 20,000 to about 1,000,000; desirably from about 200,000 to about
• Example 20 below outlines the emulsion polymerization of 1,1,2-trifluorobutadiene and butadiene.
• Example 20 (third embodiment) To a 1 liter carbonated beverage bottle was added 121g water. The water was deoxygenated by bubbling in nitrogen before mixing in any additional components. Added were 2.0 g 45 percent sodium lauryl sulfate emulsifier, 0.063 g sodium naphthalene sulfonate secondary emulsifier and 0.075 g sodium carbonate electrolyte. A magnetic stirrer bar was added to the bottle which was flushed with nitrogen and fitted with a septum. About 21.2 g 1,1,2-trifluoro-1,3-butadiene was generated per a procedure of J. Org. Chem., 52, 2304 (1988) and condensed directly into the cooled (dry ice/acetone) beverage bottle.
• the cis and trans microstructures from the hydrocarbon diene generally are hydrogenated to linear polyethylene segments which are responsible for the improved mechanical properties of the elastomer due to stretch crystallinity (A.H. Weinstein, Rubber Chemical Technology 57, 203 (1984)).
• copolymer once obtained in the third embodiment of the invention as described above is then subjected to hydrogenation in the presence of a transition metal catalyst, trialkylaluminum, and a complexing agent in the absence of BF 3 or BF 3 etherate.
• Either a homogeneous or a heterogeneous catalyst may be used for the hydrogenation although a homogeneous catalyst is preferred. Since a homogeneous catalyst dissolves in solution, good contact is obtained with the high molecular weight random polymer or copolymer.
• the homogeneous catalysts are transition metal catalysts of either iron, cobalt, or nickel. These metals are present as halides, acetates, or acetylacetonates.
• homogeneous catalysts that can be employed are palladium, platinum or rhodium present as tetrakistriphenylphosphine palladium (0), tetrakistriphenylphosphine platinum (0) or tristriphenylphosphine rhodium chloride.
• the transition metal catalyst is employed with trialkylaluminum compounds, wherein the alkyl group contains from 1 to about 4 carbon atoms, which functions as a reducing agent.
• Other reducing agents that can be employed are dialkyl aluminum hydride, the dialkyl aluminum alkoxides of 1 to 4 carbon atoms, sodium borohydride, and lithium aluminum hydride.
• other reductants are alkyl lithium, dialkyl magnesium, and alkyl magnesium halide .wherein the alkyl groups are from 1 to 4 carbon atoms, and the halide is chloride or bromide.
• the mole ratio of transition metal catalyst: reducing agent is usually from 1:10, preferably 1:6, and most preferably from 1:4.
• the transition metal catalyst complexes with a complexing agent. Without a complexing agent, addition of the catalyst to the polymer solution causes gelation. This is due to the metal ion of the transition metal catalyst complexing with the polar groups on the polymeric chains. A gelled polymer is difficult to hydrogenate to a high degree. Also, a partially crosslinked polymer results. These factors cause the elastomer to be poorer in heat aging and physical properties when compared to the polymers of this invention.
• the complexing agents complex with the catalyst in order to prevent the catalyst from excessive bonding to the polar functionalities.
• the amount of complexing agent employed is related to the relatively low catalyst level. Generally, the mole ratio of catalyst complexing agent is from 1:10, preferably 1:8; and most preferably 1:6.
• the complexing agents for the catalysts are hexamethylphosphoric triamide, tetramethylethylenediamine, phosph- ines of the general formula (R 23 ) 3 P, phosphites of the general formula (R 23 ) 3 P wherein R 23 is an alkyl group containing from 1 to about 6 carbon atoms, a phenyl group or a substituted aromatic group wherein the substituent is an alkyl group containing from 1 to 2 carbon atoms such as o-tolyl.
• Solvents for the hydrogenation are well known in the art.
• An exemplary list of solvents are xylenes, toluenes, anisole, dioxane, tetrahydrofuran, hydrocarbons such as hexanes, heptanes, and octanes and chlorinated hydrocarbons such as chlorobenzene and tetrachloroethane, trisubstituted amines such as triethylamine and tetramethylethylene diamine.
• the temperature of hydrogenation is generally from about 25°C to about 150°C with from about 25°C to about 50°C being preferred.
• the second complexing agents are weak organic acids containing from 1 to about 4 carbon atoms such as formic acid, acetic acid, and propionic acid; diacids containing from 2 to about 6 carbon atoms such as oxalic acid, malonic acid, succinic acid, glutaric acid, and adipic acid; amino acids of 1 to about 4 carbon atoms such as glycine, alanine, alphaglutaric acid, betaglutaric acid, and gammaglutaric acid; citric acid; pyridine or substituted pyridine wherein the substituent contains 1 to 2 carbon atoms; pyridine carboxylic acids such as nicotinic acid and the corresponding sodium or potassium salts; alkyl or aromatic nitriles containing from 1 to 6 carbon atoms; substituted ureas or thioureas such as N,N-dialkyldithiocarbamate metal salts of 1 to 4 carbon atoms wherein the metal is lithium, sodium, or potassium,
• Example 20 Under nitrogen, 15 grams of the product of Example 20 was dissolved in several portions in 300 ml dry tetrahydrofuran in a 500 ml three-necked round bottom flask equipped with a magnetic stirring bar. The copolymer was completely dissolved in about four hours. Preparation of the hydrogenation catalyst solution.
• the hydrogenation catalyst was then added slowly to the stirred copolymer solution.
• the copolymer solution was then transferred under nitrogen into an 800 ml pressure vessel, followed by the introduction of hydrogen (500 psi).
• the reactor was repressurized to 500 psi in order to compensate for hydrogen uptake by the copolymer.
• the copolymer solution was heated to 50°C and the hydrogen pressure increased to 1000 psi. Again, repressurization was continued to compensate for hydrogen uptake by the copolymer. After a total time of about six hours, hydrogen uptake stopped.
• the copolymer solution was then cooled to room temperature. Excess hydrogen was vented and replaced with a nitrogen blanket.
• copolymers of fluorinated 1,3-dienes with hydrocarbon 1,3-dienes are suitable for low temperature (e.g., -30°C) elastomeric applications.
• the heat resistance of these polymers is relatively poor due to the presence of the hydrocarbon segments containing carbon-carbon unsaturation sites, thus making these copolymers unsuitable for use in the area of above-described, long-felt commercial need.
• the copolymer of 1,1,2-trifluorobutadiene and butadiene displays good low temperature elastomeric properties and oil resistance, but poor heat resistance. (See Technical Report 68-56-CM by Relyea, Smith and Johnson referenced above).
• the complexed catalyst is more mobile and can reach, together with hydrogen, the desired sites of unsaturation in the butadiene segments of the copolymer, enabling hydrogenation or saturation to take place to a high degree.
• the commercially sought after, high- temperature, oil-resistant elastomer composition of the present invention thus is produced.
• the unsaturation present in the trifluorobutadiene segments of the 1,1,2- trifluorobutadiene/butadiene copolymer is not critical to the production of a high-temperature, oil-resistant elastomer composition of the present invention. More specifically, such unsaturation in the tri- fluorobutadiene segments is not detrimental to the overall thermooxidative stability of the copolymer of the invention due to the presence of the fluorine substituents in the 1,1,2-trifluorobutadiene segments.
• the ratio of aliphatic protons to vinyl protons expected is 6:3 or 2:1, which is observed in the attached spectrum in Fig. 12.
• the portion of the graph which is bracketed and extends from about .4 ppm to about 3.4 ppm represents the aliphatic protons or hydrogen atoms (i.e., 6 in number) which are attached to saturated carbons in the copolymer.
• the portion of the graph of from about 4.4 ppm to about 6.3 ppm represents vinyl protons or hydrogen atoms (i.e., 3 in number) attached to unsaturated carbon atoms of the copolymer.
• the hydrogenated copolymer of the present invention is a mixture of the structures described as Formulas D h and D h , below:
• the proton magnetic resonance spectrum of the hydrogenated copolymer of the present invention exhibits a decrease in the vinyl protons or hydrogen atoms attached to unsaturated carbon atoms of the copolymer, and an increase in the aliphatic protons or hydrogen atoms attached to saturated carbons of the copolymer. This fact is evident by viewing the peaks of Fig. 13 and comparing the same to the peaks of Fig. 12, and also by summing the vertically oriented numbers under the graph peaks, which represent the area under the respective peaks and is directly proportional to the number of hydrogen atoms attached to saturated carbon atoms and unsaturated carbon atoms in the copolymer.
• the ratio of aliphatic protons to vinyl protons in the structure of Formula D h should be 10:1, which is an increase from the 6:3 ratio observed in the unhydrogenated starting copolymer, and the structure of D h ' should be completely hydrogenated.
• the ratio of aliphatic to vinyl protons observed in the hydrogenated copolymer of the present invention which is a mixture of structures D h and D h ' is 11.8:1, indicating, in all probability, 100 percent hydrogenation of the unsaturation derived from the butadiene segment of the copolymer and partial hydrogenation of the unsaturation derived from the fluorinated diene segment of the copolymer.
• TMS in the graphs refers to tetramethylsilane.
• the infrared spectra were measured on pressed films of the polymer.

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