MXPA99005389A - Rubber compositions containing organo-nitri - Google Patents

Abstract

The present invention relates to rubber compositions containing organo-nitriles of the formula Na = CRC = N, wherein R is selected from the group consisting of alkylenes having from 2 to 10 carbon atoms, alkylenes having from 2 to 8 atoms carbon which are substituted with N, O, S, hydroxy, alkoxy having from 1 to 3 carbon atoms or an alkyl having from 1 to 3 carbon atoms, arylenes having from 6 to 10 carbon atoms and alkarylenes having from 7 to 10 atoms of carbo

Description

"RUBBER COMPOSITIONS CONTAINING ORGAN-NITRILE" FIELD OF THE INVENTION The present invention relates to a rubber composition containing organo-nitriles and the processing of rubber composites containing organo-nitriles.

BACKGROUND OF THE INVENTION Processing aids are commonly used in both natural and synthetic rubber compositions. These processing aids are used during mixing, allowing the incorporation of filling or loading materials and other ingredients quickly with lower energy consumption. In cases where the filler or filler material is silica, well-known sulfur-containing organosilicon compounds are used to further assist in compatibilizing the silica in the rubber composition.

COMPENDIUM OF THE INVENTION The present invention relates to the use of organo-nitriles in a rubber composition.

DETAILED DESCRIPTION OF THE INVENTION A method is disclosed for processing a rubber composition comprising mixing (i) 100 parts by weight of at least one elastomer containing olefinic unsaturation which is selected from the group consisting of natural rubber and conjugated diene homopolymers and copolymers and of polymers of at least one conjugated diene and an aromatic vinyl compound; with (ii) from 0.05 to 10 phr of organo-nitriles of the formula N = CRC = N wherein R is selected from the group consisting of alkylenics having from 2 to 10 carbon atoms, alkylen having from 2 to 8 atoms carbon atoms which are substituted with N, O, S, hydroxy, alkoxy having from 1 to 3 carbon atoms or an alkyl having from 1 to 3 carbon atoms, arylenes having from 6 to 10 carbon atoms and alkarylenes having they have 7 to 10 carbon atoms.

Also disclosed is a rubber composition comprising an elastomer containing olefinic unsaturation and an organo-nitrile of the formula N = CRC = N in R is selected from the group consisting of alkylenics having from 2 to 10 carbon atoms, alkyls having from 2 to 8 carbon atoms which are substituted with N, 0, S, hydroxy, alkoxy having from 1 to 3 carbon atoms or an alkyl having from 1 to 3 carbon atoms, arylenes having from 1 to 3 carbon atoms; to 10 carbon atoms and alkarylenes having from 7 to 10 carbon atoms. The present invention can be used to process rubbers or elastomers containing olefinic unsaturation. The phrase "rubber or elastomer containing olefinic unsaturation" is intended to include both natural rubber and its various untreated and regenerated forms as well as the various synthetic rubbers. In the description of this invention, the terms "rubber" and "elastomer" can be used interchangeably unless otherwise stated. The terms "rubber composition", "mixed rubber" and "rubber compound" are used interchangeably to refer to rubber that has been combined or mixed with various ingredients and materials and these terms are well known to those skilled in the art. of mixed rubber or rubber combined. Representative synthetic polymers are the products of homopolyzation of butadiene and its homologs and derivatives, for example, methylbutadiene, dimethylbutadiene and pentadiene as well as copolymers such as those formed of butadiene or its homologues or derivatives with other unsaturated monomers. Among the latter are acetylenes, for example, vinyl acetylene; olefins, for example, isobutylene, which is copolymerized with isoprene to form butyl rubber, vinyl compounds, for example, acrylic acid, acrylonitrile (which polymerizes with butadiene to form NBR), methacrylic acid and styrene, the last compound being polymerized with butadiene to form SBR, as well as the vinyl esters and the various aldehydes, ketones and unsaturated esters, eg acrolein, ethyl isopropenyl ketone and vinylethyl ether. Specific examples of synthetic rubbers include neoprene (polychloroprene), polybutadiene (including cis-1,4-polybutadiene), polyisoprene (including cis-1,4-polyisoprene), butyl rubber, styrene / isoprene / butadiene rubber, 1,3-butadiene or isoprene copolymers with monomers such as styrene, acrylonitrile and methyl methacrylate, as well as ethylene / propylene terpolymers also known as an ethylene / propylene / diene monomer (EPDM), and in particular, the ethylene / propylene / dicyclopentadiene terpolymers. The preferred rubber or elastomers are polybutadiene and SBR. In one aspect, the rubber is preferably at least two of the diene-based rubbers. For example, a combination of two or more rubbers is preferred, such as cis-1,4-polyisoprene rubber (natural or synthetic, even when natural is preferred), 3,4-polyisoprene rubber, styrene / isoprene rubber / butadiene, styrene / butadiene rubbers derived from emulsion and solution polymerization, cis-1, 4-polybutadiene rubbers and butadiene / acrylonitrile copolymers prepared by emulsion polymerization. In one aspect of this invention, a styrene / butadiene (E-SBR) derived from the emulsion polymerization could be used having a relatively conventional styrene content of from about 20 percent to about 28 percent bound styrene or, for some applications, an E-SBR that has a medium to relatively high bound styrene content; namely, a bound styrene content of from about 10 percent to about 45 percent. The relatively high styrene content of about 30 percent to about 45 percent for the E-SBR can be considered beneficial for an object of improving the attraction, or resistance to skidding of the tread surface of the rim. The presence of E-SBR itself is considered beneficial for the purpose of improving the processability of the uncured elastomer composition mixture, especially in comparison to a SBR (S-SBR) utilization prepared by solution polymerization. By the term E-SBR prepared by emulsion polymerization, it is meant that styrene and 1,3-butadiene are copolymerized as an aqueous emulsion. These terms are well known to those skilled in the art. The content of the bound styrene can vary, for example, from about 5 percent to about 50 percent. In one aspect, the E-SBR may also contain acrylonitrile to form a terpolymer rubber, such as E-SBAR, in amounts, for example, from about 2 percent to about 30 percent by weight of bound acrylonitrile in the terpolymer. Styrene / butadiene / acrylonitrile terpolymer rubbers prepared by emulsion polymerization containing from about 2 percent to about 40 weight percent bound acrylonitrile in the terpolymer are also proposed as diene based rubbers for use in this invention .

SBR (S-SBR) prepared by solution polymerization typically has a bound styrene content within the range of about 5 percent to about 50 percent, preferably from about 9 percent to about 36 percent. In S-SBR they can conveniently be prepared, for example, by organolithium catalysis in the presence of an organic hydrocarbon solvent. The object of using the S-SBR is for improved rim rolling resistance as a result of the lower hysteresis when used in a tire tread surface composition. The 3,4-polyisoprene (3,4-PI) rubber is considered beneficial for the purpose of improving the attraction of the rim when it is used in a tire tread composition. The 3,4-PI and the use thereof are more fully described in U.S. Patent No. 5,087,668 which is incorporated herein by reference. The term Tg refers to the glass transition temperature which can be conveniently determined by a differential scanning calorimeter as the heating rate of 10 ° C per minute. The cis-1, 4-polybutadiene rubber (BR) is considered as being beneficial for an object of improving wear on the tread surface of the rim or tread. This BR can be prepared, for example, by polymerization by organic solution of 1,3-butadiene. The BR can be conveniently characterized, for example, having at least a cis-1,4 content of 90 percent. The cis-1-polyisoprene rubber and the natural rubber of cis-1,4-polyisoprene are well known to those skilled in the rubber industry. The term "phr" as used herein and in accordance with conventional practice, refers to "parts by weight of a respective material per 100 parts by weight of rubber or an elastomer". The organo-nitriles used in the present invention are of the formula N = CRC = N (I) wherein R is selected from the group consisting of alkylenes having from 2 to 10 carbon atoms, alkylene having from 2 to 8 atoms carbon atoms which are substituted with N, O, S, hydroxy, alkoxy having from 1 to 3 carbon atoms or an alkyl having from 1 to 3 carbon atoms, arylenes having from 6 to 10 carbon atoms and alkarylenes having they have 7 to 10 carbon atoms. Preferred organo-nitriles are those in which R is an alkylene having from 2 to 6 carbon atoms. Representative examples of the organonitriles which may be used in the present invention include succinonitrile, glutaronitrile, adiponitrile, 1,4-cyclohexylenedinitrile, pimelonitrile, suberonitrile, phthalonitrile, isophthalonitrile, terephthalonitrile, 2-methylterephthalonitrile, 2,3-dimethylterephthalonitrile, 2,3, 5-trimethylterephthaleonitrile, 2,3,5,6-tetramethylterephthalonitrile, 2-hydroxysuccinonitrile, 2-hydroxyadiponitrile, 2-hydroxypimelonitrile, 2-hydroxysuberonitrile, 3-hydroxysuberonitrile, 2-ethoxysuccinonitrile, 2-aminosuccinonitrile, 2-N-morpholinosuccinonitrile, 2- thioethoxysuccinotril, 2-mercaptosucciononitrile, 2-methylglutaronitrile and 3-ethylglutaronitrile. The organo-nitriles used in the present invention can be added to the rubber by any conventional technique, such as in a mill or in a Banbury mixer. The amount of the organo-nitrile can vary widely depending on the type of rubber and the other compounds present in the rubber composition. Generally, the amount of the organo-nitrile will be used within a range of about 0.05 to about 10.0 phr with a scale of 0.1 to about 5.0 phr, being preferred. The organo-nitriles may be included during the unproductive stage or the productive mixing stage, but they are preferably added in the introductory step. For ease of handling, the organo-nitrile can be used per se or can be deposited in appropriate carriers. Examples of carriers that can be used in the present invention include silica, carbon black, alumina, kieselguhr, silica gel and calcium silicate. In a preferred embodiment, the rubber composition contains a sufficient amount of filler or filler material to contribute a reasonably high modulus and high breaking strength. The filler or filler material can be added in amounts ranging from 10 to 250 phr. When the filler or filler material is silica, the silica is usually present in an amount ranging from 10 to 80 phr. Preferably, the silica is present in the amount ranging from 15 to 70 phr. When the filling or loading material is carbon black, the amount of carbon black will vary from 0 to 80 phr. Preferably, the amount of carbon black will vary from 0 to 40 phr. It should be appreciated that the organo-nitrile can be used together with a carbon black. Namely, premixing with a carbon black prior to addition to the rubber composition, and this carbon black must be included in the aforementioned amount of carbon black for the formulation of the rubber composition.

The precipitated particulate silica commonly used in rubber mixing applications can be used as the silica in this invention. These precipitated silicas include, for example, those obtained by the acidification of a soluble silicate; e.g., sodium silicate. These silicas could be characterized for example, having a BET surface area, as measured using nitrogen gas, preferably within the range of about 40 to about 600, and more usually within the range of about 50 to about 300 square meters. per gram. The BET method for measuring surface area is described in Journal of the American Chemical Society, Volume 60, page 304 (1930). The silica can also typically be characterized having an absorption value of dibutyl phthalate (DBP) within a range of about 100 to about 400, and more usually about 150 to about 300. The silica could be expected to have an average final particle size, for example within the range of 0.01 to 0.05 micron, as determined by an electron microscope, even though the silica particles may be of an even smaller or possibly larger size. Various commercially available silicas such as, only as an example herein and without limitation, the silicas commercially available from PPG Industries under the trademark Hi-Sil with designations of 210, 243, etc. may be considered for use in this invention. The silicas obtainable from Rhone-Poulenc, with for example designations of Z1165MP and Z165GR and the silicas obtainable from Degussa AG with, for example, designations of VN2 and VN3. Even when the organo-nitriles improve the properties of a rubber composition filled with silica, the processing of the vulcanizable rubber with sulfur can be carried out in the presence of a sulfur-containing organosilicon compound. Examples of suitable sulfur-containing organosilicon compounds are of the formula: Z-Alk-Sn-Alk-Z (II) wherein Z is selected from the group consisting of R1 R1 R2 I I I -Si-R1 -Si-R2 -Si-R2 I I I R2, R2 and R2 wherein R1 is an alkyl group of 1 to 4 carbon atoms, cyclohexyl or phenyl; R 2 is alkoxy of 1 to 8 carbon atoms or a cycloalkoxy of 5 to 8 carbon atoms; Alk is a divalent hydrocarbon of 1 to 18 carbon atoms and n is an integer of 2 to 8. Specific examples of sulfur-containing organosilicon compounds that can be used in accordance with the present invention include: 3,3'-bis ( trimethoxysilylpropyl) disulfide, 3,3'-bis (triethoxysilylpropyl) tetrasulfide, 3,3'-bis (triethoxysilylpropyl) octasulfide, 3,3'-bis (trimethoxysilylpropyl) tetrasulfide, 2,2'-bis (triethoxysilylethyl) tetrasulfide, 3, 3'-bis (trimethoxysilylpropyl) trisulfide, 3,3'-bis (triethoxysilylpropyl) trisulfide, 3,3'-bis (tributoxysilylpropyl) disulfide, 3,3'-bis (trimethoxysilylpropyl) hexasulfide, 3,3'-bis (trimethoxysilylpropyl) ) octasulfide, 3,3'-bis (trioctoxysilylpropyl) tetrasulfide, 3,3'-bis (trihexoxysilylpropyl) disulfide, 3,3'-bis (tri-2"-ethylhexoxysilylpropyl) trisulfide, 3,3'-bis (triisooctoxysilylpropyl) tetrasulfide, 3, 3'-bis (tri-t-butoxysilylpropyl) disulfide, 2,2'-bis (methoxydiethoxysilylethyl) tetrasul furo, 2,2'-bis (tripropoxysilylethyl) pentasulfide, 3,3'-bis (tricyclohexoxysilylpropyl) tetrasulfide, 3,3'-bis (tricyclopentoxysilylpropyl) trisulfide, 2,2'-bis (tri-2"-methylcyclohexoxysilylethyl) tetrasulfide , bis (trimethoxysilylmethyl) tetrasulfide, 3-methoxyethoxy-propoxysilyl-3'-diethoxybutoxysilylpropyltetrasulfide, 2,2'-bis (dimethylmethoxysilylethyl) disulfide, 2,2'-bis (dimethyl-sec.butoxylylethyl) trisulfide, 3,3'-bis (methyl-butylethoxysilylpropyl) tetrasulfide, 3,3'-bis (di-t-butylmethoxysilylpropyl) tetrasulfide, 2,2'-bis (phenyl-methyl-methoxysilylethyl) trisulfide, 3'3'-bis (diphenyl-isopropoxysilylpropyl) tetrasulfide, 3,3'-bis (diphenyl-cyclohexoxysilylpropyl) disulfide, 3,3'-bis (dimethyl ethylmercaptosilylpropyl) tetrasulfide, 2,2'-bis (methyl dimethoxysilylethyl) trisulfide, 2,2'-bis (methyl ethoxypropoxy-silylethyl) tetrasulfide, 3, 3'-bis (diethylmethoxysilylpropyl) tetrasulfide, 3,3'-bis (ethyl di-sec.butoxysilylpropyl) disulfide, 3,3'-bis (propyldiethoxysilylpropyl) disulfide, 3,3'-bis (butyldimethoxysilylpropyl) trisulfide, 3,3'-bis (phenyldimethoxysilylpropyl) tetrasulfide, 3-phenylethoxybutoxysilyl-3'-trimethoxysilylpropyltetrasulfide, 4,4'-bis (trimethoxysilylbutyl) tetrasulfide, 6,6'-bis (triethoxysilylhexyl) tetrasulfide, 12, 12'-bis (triisopropoxysilyldodecyl) disulfide, 18,18'-bis (trimethoxysilyloctadecyl) tetrasulfide, 18,18'-bis (tripropoxysilyloctadecenyl) tetrasulfide, 4,4'-bis (trimethoxysilyl-buten-2-yl) tetrasulfide, 4,4'-bis ( trimethoxysilylcyclohexylene) tetrasulfide, 5,5'-bis (dimethoxymethylsilylpentyl) trisulfide, 3,3'-bis (trimethoxysilyl-2-methylpropyl) tetrasulfide, 3,3 ' -bis (dimethoxyphenylsilyl-2-methylpropyl) disulfide. Preferred sulfur-containing organosilicon compounds are the 3,3'-bis (trimethoxy or triethoxysilylpropyl) sulfides. The especially preferred compound is 3, 3'-bis (triethoxysilylpropyl) tetrasulfide.

Therefore, as for formula II, preferably Z is R2 I -Si-R2 I R2 wherein R2 is an alkoxy of 2 to 4 carbon atoms, with 2 carbon atoms being particularly preferred; Alk is a divalent hydrocarbon of 2 to 4 carbon atoms with 3 carbon atoms being particularly preferred; and n is an integer from 3 to 5 with 4 being particularly preferred. The amount of the sulfur-containing organosilicon compound of the formula II in a rubber composition will vary depending on the level of silica used.

Generally speaking, the amount of the compound of formula II, if used, will vary from .01 to 1.0 part by weight per part by weight of the silica. Preferably, the amount will vary from 0.05 to 0.4 part by weight per part by weight of the silica. It will be readily understood by those skilled in the art that the rubber composition would be mixed by methods generally known in the rubber mixing art, such as the mixing of the various vulcanizable constituents with sulfur with various commonly used additive materials such as for example, sulfur donors, curing aids, such as activators and retarders and processing additives, such as oils, resins including tackifying resins and plasticizers, fillers or fillers, pigments, fatty acid, zinc oxide, waxes, antioxidants and antiozonants and peptizing agents. As is known to those skilled in the art, depending on the intended use of the material (rubbers), vulcanizable with sulfur and vulcanized with sulfur, the aforementioned additives are selected and commonly used in conventional amounts. Typical amounts of carbon black (s), of the reinforcing type for this invention, if used, are disclosed herein. Representative examples of sulfur donors include elemental sulfur (free sulfur), an amine disulfide, polymeric polysulfide, and sulfur olefin adducts. Preferably, the sulfur vulcanization agent is elemental sulfur. The sulfur vulcanization agent can be used in an amount ranging from 0.5 to 8 phr, being especially preferred in the range of 1.5 to 6 phr. Typical amounts of tackifying resins, if used, comprise from about 0.5 to about 10 phr, usually from about 1 to about 5 phr. Typical amounts of processing aids comprise from about 1 to about 50 phr. These processing aids may include, for example, aromatic, naphthenic and / or paraffinic processing oils. Typical amounts of antioxidants comprise from about 1 to about 5 phr. Representative antioxidants, for example, may be diphenyl-p-phenylenediamine and others, such as, for example, those disclosed in Vanderbilt Rubber Handbook (1978), pages 344 to 346. Typical amounts of antiozonants comprise from about 1 to 5 phr. Typical amounts of fatty acids, if used, which may include stearic acid comprise from about 0.5 to about 3 phr. Typical amounts of zinc oxide comprise about 2 a - l approximately 5 phr. Typical amounts of waxes comprise from about 1 to about 5 phr. Frequently microcrystalline waxes are used. Typical amounts of peptizers comprise from about 0.1 to about 1 phr. Typical peptizers can be, for example, pentachlorothiophenol and dibenzamidodiphenyl disulfide. In one aspect of the present invention, the rubber composition vulcanizable with sulfur is then cured or vulcanized with sulfur. Accelerators are used to control the time and / or temperature required for vulcanization and to improve the properties of the vulcanized material. In one embodiment, a single accelerator system can be used; that is, a primary accelerator. The primary accelerator (s) may be used in total amounts ranging from about 0.5 to about 4, preferably from about 0.8 to about 1.5, phr. In another embodiment, combinations of a primary and a secondary accelerator could be used with the secondary accelerator being used in smaller amounts, such as from about 0.05 to about 3 phr, in order to activate and improve the properties of the vulcanized material. The combinations of these accelerators could be expected to produce a synergistic effect on the final properties and are somewhat better than those produced by the use of any single accelerator. In addition, delayed action accelerators which are not affected by normal processing temperatures can be used but produce a satisfactory cure at regular vulcanization temperatures. Vulcanization retarders could also be used. The appropriate types of accelerators that can be used in the present invention are amines, disulfides, guanidines, thioureas, thiazoles, thiouramyls, sulfena idas, dithiocarbamates and xanthates. Preferably, the primary accelerator is a sulfenamide. If a second accelerator is used, the secondary accelerator is preferably a guanidine, dithiocarbamate or a thiouramyl compound. The rubber compositions of the present invention may contain a methylene donor and a methylene acceptor. The term "methylene donor" is intended to mean a compound capable of reacting with a methylene acceptor (such as a resorcinol or its equivalent containing a hydroxyl group present) to generate the resin in-situ. Examples of methylene donors which are suitable for use in the present invention include hexamethylenetetramine, hexaethoxymethylmelamine, hexametoxy ethylmelamine, lauryloxymethylpyridinium chloride, ethoxymethylpyridinium chloride, trioxane hexametoxymethylmelamine, the hydroxy groups of which can be partially esterified or esterified and formaldehyde polymers such as paraformaldehyde. In addition, the methylene donors may be N-substituted oxymethylmelamines of the general formula: N N N R3 \ R4 wherein X is an alkyl having from 1 to 8 carbon atoms, R ^,? 4, R5; R6 and p > 7 are individually selected from the group consisting of hydrogen, an alkyl having from 1 to 8 carbon atoms and the group -CH 2 OX. Specific methylene donors include hexakis- (methoxymethyl) elamine, N, N ', N "-trimethyl / N, N', N" -trimethylolmelamine, hexamethyloltelamine, N, N ', N "-dimethylolmelamine, N-methylolmelamine, N , N'-dimethylol elamine, 'N, N', N "-tris (methoxymethyl) melamine and N, N'-N" -trim-N, N'-N "-trimethylol-melamine. The melamine N-methylol derivatives are prepared by known methods.

The amount of the methylene donor and the methylene acceptor that are present in the rubber material can be varied. Typically, the amount of methylene donor and methylene acceptor that are present will vary from about 0.1 phr to 10.0 phr. Preferably, the amount of the methylene donor and the methylene acceptor ranges from about 2.0 phr to 5.0 phr for each. The weight ratio of the methylene donor to the methylene acceptor can vary. Generally speaking, the weight ratio will vary from approximately 1:10 to approximately 10: 1. Preferably, the weight ratio ranges from about 1: 3 to 3: 1. The mixing of the rubber composition can be achieved by methods known to those skilled in the rubber mixing art. For example, the ingredients are typically mixed in at least two stages; namely, at least one unproductive stage followed by a stage of productive mixing. The final curing agents including the sulfur vulcanization agents are typically mixed in the final stage which is conventionally called the "productive" mixing stage in which the mixing typically occurs at a temperature, or final temperature lower than the temperature ( s) of the mixture, than that of the previous unproductive mixing stage (s). The rubber and organ-nitrile are mixed in one or more unproductive mixing stages. The terms "unproductive" and "productive" mixing stages are well known to those skilled in the rubber mixing art. The rubber composition containing the organo-nitrile, the rubber, the silica and a sulfur-containing organosilicon compound, if used, can be subjected to a thermomechanical mixing step. The thermomechanical mixing step usually comprises a mechanical treatment in a mixer or extrusion apparatus for an appropriate period of time in order to produce a rubber temperature of between 140 ° C and 190 ° C. The proper duration of the thermomechanical treatment varies as a function of the operating conditions and the volume and nature of the components. For example, the thermomechanical treatment can be from 4 to 20 minutes. The vulcanization of the rubber composition of the present invention is generally carried out at conventional temperatures ranging from about 100 ° C to 200 ° C. Preferably, the vulcanization is carried out at temperatures ranging from about 110 ° C to 180 ° C. Any of the usual vulcanization processes such as heating in a press or mold, heating with superheated steam or hot air or in a salt bath can be used.

After vulcanization of the composition vulcanized with sulfur, the rubber composition of this invention can be used for various purposes. For example, the rubber composition vulcanized with sulfur can be in the form of a rim, belt or hose. In case of a tire, it can be used for several rim components. These rims can be made, configured, molded and cured by different methods that are known and will be readily apparent to those skilled in this art. Preferably, the rubber composition is used on the running surface of a rim. As you can see, the rim can be a rim for a passenger car, an airplane tire, a truck tire and the like. Preferably, the rim is a passenger car tire. The rim can also be a radial or bias rim, with a radial rim being preferred. The invention may be better understood by reference to the following examples wherein the parts and percentages are by weight unless otherwise indicated. The following examples are presented in order to illustrate but not to limit the present invention. Curing properties were determined using a Monsanto oscillating disk rheometer which was operated at a temperature of 150 ° C and at a frequency of 11 hertz. A description of the oscillatory disc discs can be found in the Vanderbilt Rubber Handbook edited by Robert O. Ohm (of Nor alk, Conn., RT Vanderbilt Company, Inc., 1990), pages 554 to 557. The use of this meter of cure and the normalized values read from the curve are specified in Method D-2084 of the American Society for the Testing of Materials. A typical cure curve obtained in an oscillating disc rheometer is shown on page 555 of the 1990 edition of the Vanderbilt Rubber Handbook. In this oscillating disc rheometer, the mixed rubber samples were subjected to an oscillatory shearing action of constant amplitude. The torque of the oscillating disc embedded in the material being tested that is required to oscillate the rotor at the vulcanization temperature is, of course, measured. The values obtained using this cure test are very significant since the changes in the rubber or the mixing recipe can be detected very easily. It is clear that it is usually advantageous for there to be a rapid cure regime. The invention may be understood by reference to the following examples wherein the parts and percentages are by weight unless otherwise indicated.

Example 1 In this example, they were valued from succinonitrile, adiponitrile, pimelonitrile and suberonitrile in a rubber compound containing carbon black and silica. The rubber compositions containing the materials indicated in Tables 1 and 2 were prepared in a BR Banbury ™ mixer using three separate stages of addition (mixing); namely, two unproductive mixing stages and one stage of productive mixing. The first unproductive stage was mixed for up to 4 minutes or until a rubber temperature of 160 ° C any of which occurred first. The second unproductive stage was mixed for 7 minutes at 160 ° C. The mixing time for the production stage was at a rubber temperature of 120 ° C for 2 minutes. The rubber compositions were identified herein as Samples 1 to 5. Sample 1 is considered herein as being a control without the use of any organo-nitrile added during the unproductive mixing step. - 2( The samples were cured at a temperature of 150 ° C for approximately 36 minutes. Table 2 illustrates the behavior and physical properties of cured samples 1 to 5. It is clearly evident from the results that the use of organo-nitriles in a rubber compound containing carbon black and silica, provide a lower minimum rheometer torque which would indicate a lower work input required during mixing in the Banbury mixer and an improved processing compound. The organo-nitriles also provide improved investment strength and a higher modulus of E 'deformation as measured by Rheovibron. The succinonitrile also provides a higher stress-strain modulus and higher hardness values.

Table 1 Ex. 1 Ex. 3 E Ex First unproductive mix Polyisoprene 100 100 100 100 100 Carbon Black 15 15 15 15 15 Silica2 20 20 20 20 20 Processing Oil Silane Coupling Agent3 (50%) 3 3-3 3 3 Zinc oxide Fatty acid Antioxidant Table 1 (continued) Second unproductive mix Silica '15 15 15 15 15 Silane3 Coupling Agent (50%) Succinonitrile ^ (50%) Adiponitrile5 (50%) 0 Pimelonitrile (100%: Suberonitrile5 (50%) 0 Productive Mix Sulfur 1.5 1.5 1.5 1.5 1.5 Accelerator, sulfenamide 2 Accelerator, diphenylguanidine 0.5 0.5 0.5 0.5 0.5 -Cis-l, synthetic 4-polyisoprene obtainable commercially from The Goodyear Tire & Rubber Company under the designation Natsyn® 2200 Precipitated silica which can be obtained commercially from PPG Company under the designation of Hil Sil ™ 210 3 Obtained as bis- (3-triethoxysilylpropyl) tetrasulfide, which can be obtained commercially as X50S from Degussa Gmbh and is provided in a 50/50 mixture by weight with carbon black. 2, 2,4-trimethylquinoline 1,2-dihydro of polymerized type ^ 50/50 by weight mixture with carbon black.

Table 2 Samples Succinonitrile Adiponitrile Pimelonitrile Suberonitrile Rheometer 150 ° C Maximum Torque 41.8 48.4 41.2 42.1 43.1 Minimum Torque 5.1 5.1 4.6 4.8 4.8 Torque Torque? 36.7 44 36.6 37 38.8 t90 19.3 21.3 18.1 18.2 18.2 Reversion to 60 minutes 0.18 0.05 0.05 0.09 Effort and Deformation 36 'at 150 ° C 100% of M (MPa) 2.63 2.96 2.56 2.60 2.56 300% of M (MPa) 11.6 12.3 11.0 11.2 11.0 Resistance to Tension (MPa) 22.8 21.3 22.6 22.0 22.6 Elongation at Break (%) 546 507 557 543 556 Hardness Ambient Temperature 66.3 71.7 66.7 67.1 65.8 100C 64.1 68.1 64.0 64.4 63.5 Rebound Ambient Temperature 50.6 49.2 50.2 49.4 51.4 100C 67.5 63.8 66.1 66.1 66.9 E ', 60 ° C, (MPa) 17.1 27.9 21.8 18.0 20.0 Tan Delta .056 .051 .062 .052 .060 DIN Abrasion (the lower the better) 144 149 147 140 141 Example 2 In this example, succinonitrile, adiponitrile, pimelonitrile and suberonitrile were evaluated in a rubber compound containing carbon black. The rubber compositions containing the materials listed in Tables 3 and 4 were prepared in a BR Banbury ™ mixer using three separate addition steps (mixed); namely, two unproductive mixing stages and one stage of productive mixing. The first stage is mixed unproductively mixed for up to 4 minutes or until a rubber temperature of 160 ° C any of which occurred first. The second stage of unproductive mixing was mixed for 7 minutes at 160 ° C. The second unproductive stage was a re-mix of the unproductive first stage without additional materials added. The mixing time for the production stage was up to a rubber temperature of 120 ° C for 2 minutes. The rubber compositions were identified herein as samples 1 to 5. Sample 1 is considered herein as being a control without the use of any organo-nitrile added during the unproductive mixing step.

The samples were cured at a temperature of about 150 ° C for about 36 minutes. Table 4 illustrates the behavior and physical properties of cured samples 1 to 5. It will be clearly evident from the results that the use of organo-nitriles does not provide a reduction in the minimum torque with carbon black as shown for Example 1 containing carbon black and silica. However, they still provide improved reversion resistance and a slightly higher modulus of low E 'deformation. The succinonitrile again provided a higher stress-strain modulus and hardness values.

Table 3 Sample Number First unproductive mix Polyisoprenol 100 100 100 100 100 Carbon Black 50 50 48 50 48 Processing Oil Zinc oxide Fatty acid Antioxidant2 Succinonitrile3 (50%) Adiponitrile3 (50% 0 0 Pimelonitrile (100%) 0 0 0 Suberonitrile3 (50%) 0 0 0 0 0 Second Unproductive Mixture Productive Sulfur 1.4 '1.4 1.4 1.4 1.4 Accelerator - sulfenamide lcis-1, synthetic polyisoprene obtainable commercially from The Goodyear Tire & Rubber Company under the designation Natsyn® 2200. 22, 2, 1,2-dihydro-trimethylquinoline of polymerized type. 50/50 by weight of mixture with carbon black.

Table 4 Samples Succinonitrile (50%) Adiponitrile (50%; Pimelonitrile (100%) Suberonitrile (50%) Rheometer 150 ° C Maximum Torque Torque 34.6 37.3 34.3 35.7 34.7 Minimum Torque Torque 6.6 7.1 7 7.3 7 Torque Torque? 28 30.2 27.3 28.4 27.7 t90 14.9 12.0 10.6 13.2 11.9 Reversion to 60 minutes 0.44 0.04 0.19 0.26 0.01 Effort and Deformation 36 'at 150 ° C 100% of M (MPa) 1.92 2.21 2.02 2.05 1.94 300% of M (MPa) 10.1 11.1 10.6 10.8 10.2 Resistance to Tension (MPa) 23.0 23.1 23.1 22.5 22.9 Elongation at Break (%) 576 557 568 555 571 Hardness Ambient Temperature 61.7 66.8 62 61.3 60.3 100C 56.9 60.6 57.5 57.6 55.7 Rebound Ambient Temperature 46.8 44.5 44.7 44.7 45.9 100C 61.4 59.1 61.1 60.6 60.6 E ', 60 ° C, (MPa) 19.0 24.3 20.4 21.2 20.4 Tan Delta .070 .067 .068 .072 .073 DIN Abrasion (the lower the better) 128 129 120 124 127 Even though certain details and representative modalities have been shown for the purpose of illustrating the invention, it will be evident to those skilled in the art that various changes and modifications may be made therein. modifications without deviating from the spirit or scope of the invention.

Claims (17)

CLAIMS:

1. A method for processing a rubber composition which is characterized by mixing (i) 100 parts by weight of at least one elastomer containing olefinic unsaturation which is selected from the group consisting of natural rubber, conjugated diene homopolymers and copolymers and copolymers of at least one conjugated diene and an aromatic vinyl compound; with (ii) from 0.05 to 10 phr of an organo-nitrile of the formula N = CRC = N (I) wherein R is selected from the group consisting of alkyls having from 2 to 10 carbon atoms, alkyls having 2 to 8 carbon atoms which are substituted with N, O, S, hydroxy, alkoxy having from 1 to 3 carbon atoms or an alkyl having from 1 to 3 carbon atoms, arylenes having from 6 to 10 carbon atoms carbon and alkarylenes having from 7 to 10 carbon atoms.

2. The method of claim 1, characterized in that there is present from 10 to 250 phr of a filler or filler.

The method of claim 1, characterized in that the organo-nitrile is selected from the group consisting of succinonitrile, adiponitrile, glutaronitrile, pimelonitrile, suberonitrile and 2-methylglutaronitrile.

4. The method of claim 2, characterized in that the filler or filler material is silica.

The method of claim 4, characterized in that a sulfur-containing organosilicon compound is present and is of the formula: Z-Alk-Sn-Alk-Z (II) wherein Z is selected from the group consisting of R1 R1 R2 I I I -Si-R1 -Si-R2 -Si-R2 I I I R2, R2 and R2 wherein R1 is an alkyl group of 1 to 4 carbon atoms, cyclohexyl or phenyl; R 2 is alkoxy of 1 to 8 carbon atoms or cycloalkoxy of 5 to 8 carbon atoms; Alk is a divalent hydrocarbon of 1 to 18 carbon atoms and n is an integer of 2 to 8.

The method of claim 5 characterized in that the sulfur-containing organosilicon compound is present in an amount ranging from 0.01 to 1.0. part by weight per part by weight of silica.

7. The method of claim 1 characterized in that the elastomer containing olefinic unsaturation is selected from the group consisting of natural rubber, neoprene, polyisoprene, butyl rubber, polybutadiene, styrene-butadiene copolymer, styrene / isoprene / butadiene rubber, copolymer methyl methacrylate butadiene, copolymer of isoprene and styrene, copolymer of methyl methacrylate and isoprene, copolymer of acrylonitrile and isoprene, copolymer of acrylonitrile and butadiene, EPDM and mixtures thereof.

The method of claim 1, characterized in that the rubber composition is thermomechanically mixed at a rubber temperature within the range of 140 ° C to 190 ° C for a mixing time of 4 to 20 minutes.

9. A rubber composition characterized by an elastomer containing olefinic unsaturation and an organo-nitrile of the formula: N = CRC = N (I) wherein R is selected from the group consisting of alkylenics having from 2 to 10 carbon atoms. carbon, alkyls having 2 to 8 carbon atoms and substituted with N, O, S, hydroxy, alkoxy having 1 to 3 carbon atoms or an alkyl having 1 to 3 carbon atoms, arylenes having they have from 6 to 10 carbon atoms and alkarylenes having from 7 to 10 carbon atoms.

10. The composition of claim 9, characterized in that 10 to 250 phr of a filler or filler is present.

The composition of claim 9, characterized in that the organo-nitrile is selected from the group consisting of succinonitrile, adiponitrile, glutonitrile, pimelonitrile, suberonitrile and 2-methylglutaronitrile.

12. The composition of claim 10, characterized in that the filler or filler material is silica.

The composition of claim 12, characterized in that the sulfur-containing organosilicon compound is present and is the formula: Z-Alk-Sn-Alk-Z (II) wherein Z is selected from the group consisting of R1 R1 R2 I I I -Si-R1 -Si-R2 -Si-R2 I I R2, R2 and R2 wherein R is an alkyl group of 1 to 4 carbon atoms, cyclohexyl or phenyl; R 2 is alkoxy of 1 to 8 carbon atoms or cycloalkoxy of 5 to 8 carbon atoms; Alk is a divalent hydrocarbon of 1 to 18 carbon atoms and n is an integer of 2 to 8.

The composition of claim 13, characterized in that the organosilicon compound containing sulfur is present in an amount ranging from .01 to 1.0 part by weight per part by weight of silica.

The composition of claim 9 characterized in that the elastomer containing the olefinic unsaturation is selected from the group consisting of natural rubber, neoprene, polyisoprene, butyl rubber, polybutadiene, styrene-butadiene copolymer, styrene / isoprene / butadiene rubber , copolymer of methyl methacrylate and butadiene, copolymer of isoprene and styrene, copolymer of methyl methacrylate and isoprene, copolymer of acrylonitrile and isoprene, copolymer of acrylonitrile and butadiene, EPDM and mixtures thereof.

The composition of claim 9, characterized in that the composition is thermomechanically mixed at a rubber temperature within the range of 140 ° C to 190 ° C for a total mixing time of 4 to 20 minutes.

17. The composition of claim 9, in the form of a rim, belt or hose.