IL36769A - Carbon black pigments and rubber compositions - Google Patents

Description

CARBON BLACK FIGMENTS AND RUBBER COMPOSITIONS ■>zm niavwn on mn iz? D^aajs This invention relates to a new class of active carbon black products. In particular, this invention relates to novel and important carbon black products which exhibit relatively low porosity and. posses an unusually high numerical product for the combination of carbon monoxide content expressed in millimoles per gram of the particular carbon blacks and the specific surface areas in square meters per gram thereof. , The numerical product of the carbon monoxide content and the specific surface area of the carbon blacks in hereinafter referred to as the activity factor of the novel carbon blacks.

Furthermore, this invention relates to the use of the novel active carbon blacks in the preparation of new and -useful natural and synthetic rubber compositions having improved physical properties.

Normally, there have been widely employed as fillers and reinforcing pigments in the compounding and preparation of rubber compositions various conventional carbon blacks are effective in the preparation of rubber vulcanizates having improved reinforcement properties 'such as tensile strength or elongation. The improvement in properties exhibited by an elastomeric article or rubber stock filled with a carbon black will depend to a great extent upon the type of elastomer utilized and the particular carbon black incorporated therein. How- , with several of the more recently developed synthetic rubbers has proven difficult as a result of the increased inertness and reduced reactivity thereof. Typically, the newer synthetic rubbers are commercially desirable for use as general purpose or heavy duty rubber stocks because of the low amount of unsaturation, contained therein. Although some improvements have been achieved, for example, by aftertreating carbon blacks, it has now been made possible by using the active carbon black products of the present invention to provide finished products having still further improved tensile, hardness, modulus and abrasion-resistant qualities.

Accordingly, it is a primary object of this invention to provide a novel type of active carbon black products .

It is a further object of this invention to provide a suitable carbon black reinforcing additive for natural and synthetic rubbers which provides the desired physical properties to the resultant composition.

Other objects and advantages of the present invention will be apparent to those skilled in the art. from the following detailed description and claims.

In accordance with this invention, it has been found that the above and still further objects are achieved by the preparation of novel active carbon blacks which possess relatively low porosity and which are further characterized by having an unusually high numerical product of carbo monoxide content expressed in millimoles per gram and BET specific surface area where the carbon black is non-porous or "t" curve specific surface area where the black is porous and, additionally, a relatively high dibutyl phthalate (DBP) absorption value. " :" Specifically, the novel active class of carbon black products of the present invention are characterized by possessing an activity factor numerical value representing the product of BET surface area, in the instance of non-porous blacks, or "t" curve area where, the blacks exhibit porosity, and the carbon monoxide content, which is at least 62, a ratio of non-porous "t" curve area to total BET surface area of the carbon black which is at least about 0.8, and DBP absorption value of at least 110. It is, however, preferred that the numerical value for the activity factor of these novel blacks vary from about 62 to about 125, and in a more preferred embodiment, ranges from about 65 to about 99. Moreover, with regard to the porosity of the active carbon blacks it is especially desirable that the ratio of non-porous specific surface area of the carbon blacks to the total specific surface area thereof exceed 0.9.

It is further preferred that the DBP absorption values of these carbon blacks range from about 130 to about 180 or higher and, in a particularly preferred embodiment, the novel active carbon blacks possess DBJP values ranging from about 150 to about 170.

Generally, amounts of the active carbon black product ranging from about 10 to about 250 parts by weight can be used for each 100 parts by weight of rubber in order to impart a significant degree of .reinforcement thereto. It is, however, preferred to use amounts varying from about 20 to 100 parts by weight of carbon black per 100 parts by weight of rubber and especially preferred is the utilization of from about 40 to about 80 parts of parbon black per 100 parts of rubber.

The rubbers for which the novel active carbon blacks of this invention are effective as reinforcing agents include natural rubber and synthetic rubbers.

Among the rubbers suitable for use with the present invention are natural rubber and its derivatives such as chlorinated rubber; copolymers of from about 10 to about 70 percent by weight of styrene and from about 90 to about 30 percent by weight of butadiene such as a copolymer of 10 parts styrene and 90 parts butadiene, a copolymer of 19 parts styrene and 81 parts butadiene, a copolymer of 23.5 parts styrene and 76.5 parts butadiene, a copolymer of 30 parts styrene and 70 parts butadiene, a copolymer of 43 parts styrene and 57 parts butadiene and a copolymer of 50 parts styrene and 50 parts butadiene; polymers and copolymers of conjugated diene such as polybutadiene, polyisoprene, polychloroprene , and the like, and copolymers of such conjugated dienes with an ethylenic group- * containing monomer copolymerizable therewith such as styrene, methyl strene, chlorostyrene, acrylonitrile, 2-vinylpyridine, 5-methyl-- 2-vinylpyridine , 5-ethyl-2-. vinylpyridine , 2-methyl-5-vinylpyridine, alkyl- substituted acrylates such as methyl acrylate, alkyl- substituted methacrylates such as methyl methacrylate , ethyl acrylate, ethyl methacrylate, ethyl vinyl ketone, methyl isopropenyl ketone, methyl vinyl ether, alphamethylene carboxylic acids and the esters and amides thereof such as acrylic.

The heretofore-described class of novel active carbon blacks are readily prepared by contacting a carbon black- producing feedstock with a stream of hot combustion gases flowing at an average linear velocity of at least 100 feet per second. The process for preparing the novel carbon blacks of the present invention will be described in greater detail hereinafter.

In the preparation of the hot combustion gases employed in producing the active carbon blacks of the present invention there are reacted in any conventional combustion chamber a liquid, or. gaseous fuel and an oxygen-containing oxidant stream. Exemplary oxidant streams include air, oxygen, mixtures of air and oxygen, nitrogen and oxygen, and other mixtures of oxygen with common gases. It is preferred, however, that the oxidant stream to be used in the present invention comprise an amount greater than about 507o molar concentration of oxygen. Among the fuels suitable for use in reacting with an oxidant stream in a combustion chamber to generate ho combustion gases there are included any of the readily combustible gas, vapor or liquid streams such as hydrogen," carbon monoxide, methane, acetylene, alcohols, kerosene, and the like. It is generally preferred, however, to utilize fuels having a high content of carbon-containing components and, in particular, hydrocarbons. For example, streams rich in methane such as natural gas and modified or enriched natural gas are excellent fuels as well as other streams containing high amounts of hydrocarbons such as various petroleum gases and liquids and refinery by-products including ethane through pentane fractions, fuel oils and the like. In General, the heavier and more viscous tars and residual type oils should preferably be used with the more concentrated or relatively pure oxygen-containing oxidant streams.

The novel active carbon blacks of the present invention are prepared by reacting the aforementioned combustion reaction products with any of a wide variety of hydrocarbon feedstocks which are readily volatilizable under the conditions of the reaction. Suitable for use in the present invention as hydrocarbon feedstocks are unsaturated hydrocarbons such as acetylene, olefins such as ethylene, propylene, butylene, aromatics such as benzene, toluene and xylene, saturated hydrocarbons such as methane, natural gas, ethane and propane and volatilized hydrocarbons such as kerosenes, naththalenes , terpenes, ethylene tars, aromatic cycle stocks and the like Accordingly, the above-described novel class ofactive carbon blacks are prepared by reacting a carbon black-yielding hydrocarbon feedstock with hot gaseous products of an initial combustion reaction which are flowing at a high linear velocity in a suitable reaction zone. The hot combustion gases are readily generated by contacting the desired oxidant stream with a combustible fuel in any type of conventionally known burner designed to produce a stream of hot combustion gases flowing at a high linear velocity. In a preferred embodiment of the present invention, a combustible fuel is contacted with an oxidant stream ontaining at least 50% molar concentration of oxygen in a suitable burner under a pressure ranging up to about 120 psig with the most preferred combustion pressure varying from about 5 to about 75 psig. Under these conditions, there is produced a stream of gaseous combustion .products possessing sufficient energy to convert a carbon black-yielding hydrocarbon feedstock to the desired active carbon black products. The resultant combustion gases emanating from the combustion zone may attain temperatures up to and greater than 5000 to 6000° F . , with the most preferable temperatures for the present process being at least about 3000° F. The hot combustion gases are propelled in an upstream direction at a high linear velocity which may be effectuated by passing the combustion gases through any suitable passage or inlet which may be tapered or restricted such as a conventional ventiru throat. Into the resultant stream of hot combustion gases traveling at a high velocity there is then introduced a suitable carbon black-yielding hydrocarbon feedstock thus insuring a high rate of mixing and shearing of the hot combustion gases and the hydrocarbon feedstock so as to rapidly and completely decompose and convert the feedstock to the novel carbon blacks in high yields. The manner in which the carbon black-yielding hydrocarbon feedstock is introduced into the hot combustion gases traveling upstream at a high linear velocity may be varied considerably. For example, the hydrocarbon feedstock may be introduced into the hot combustion gases through an opening in the reaction chamber which causes the entry to be in a direction perpendicular to the longitudinal axis of the flow of combustion gases.

Alternately, the hydrocarbon feedstock may be introduced through a suitable probe type device into the reaction zone in a direction paralleling that of the flow of the combustion gases. It is preferred, however, that the hydrocarbon feedstock be injected substantially transversely from the periphery of the stream of hot combustion gases in the form of a single or a plurality of small, coherent jets which penetrate into the interior regions of the stream of combustion gases. It is to be understood of course, that in practicing the present process the hydrocarbon feedstock may be introduced into the reaction zone as a liquid or liquid spray by means of a conventional atomizer or spray nozzle as well as in the form of a gas or vapor. Following the period of reaction in the reaction zone, the effluent gases containing the novel active carbon black products suspended therein are passed downstream to any conventional cooling and separating means whereby the novel active carbon blacks are recovered. The separation of the carbon black from the gas stream is readily accomplished by conventional means such as a precipitator, cyclone separator and bag filter. The amounts of oxidant gas, fuel and carbon black-yielding hydrocarbon feedstock may be readily determined to obtain the desired active carbon blacks having controlled physical properties. Moreover, although the residence time for each instance depends upon the particular reaction conditions and the particular carbon black desired, the residence time of the present process may vary from about 1 to about 100 milliseconds, or even shorter periods of time.

The following testing procedures are used in the determination and evaluation of the physical properties and efficiency of the novel active carbon blacks of the present invention. ·' DBF Absorption - In accordance with the procedure set forth in ASTM D-2414-65T, absorption characteristics of pelleted carbon blacks are determined. In brief, the test procedure entails adding dibutyl phthalate (DBP) to a pelleted carbon black until a transition from a free-flowing powder to a semi-plastic agglomerate results in a sharp increase in viscosity.

■ Carbon Monoxide Content - Carbon monoxide content of carbon blacks are determined by a pyrolytic volatile . analysis (FVA) technique wherein the carbon black is devolatilized at a linear heating rate up to a temperature of 1500° C. and the gases evolved thereby are quantitatively determined by gas chromatographic procedures. A more complete description of the pyrolytic volatile "analysis procedure appears in an article by Cotten, Boonstra, Rivin and Williams entitled "Effect of Chemical Modification of Carbon Black on Its Behavior in Rubber", Kautschuk Und Gummi . Kunstoffe 22 (9), 77-485 (1969) . , . . 7 Total Surface Area - The total surface of the carbon blacks is masured in accordance with the well-known BET technique utilizing nitrogen isotherms. The BET (Brunauer-Emmet-Teller) method is completely described in an article appearing in the Journal of the American Chemical Society, Volume 60, page 309 (1938). Surface areas obtained in the usual manner by BET technique include the external surface area as well as the internal surface area contributed by the presence of pores. "t" Area - Surface area of carbon black measured in accordance with a "t curve method" is referred to herein as "t" area. The "t curve method" for evaluating microporosity of carbon, black is a comparative '. procedure and is fully described in an article by Mikhail, Brunauer and Bodor entitles "investigations of a Complete Pore Structure Analysis" in the Journal of Colloid and Interface Science, Volume 26, pages 45-53 (1968). The technique taught in this article is followe with the exception that the "master t curve" utilized is one for which Sterling FT carbon black extracted with benzene serves as the non- orous, solid standard adsorbent inasmuch as it is more advantageous to employ a carbon black as the master adsorbent when evaluating carbon blacks. The carbon black selected as the standard, i.e. Sterling FT, is manufactured and sold by CABOT CORPORATION and. is characterized by having a Nigrotneter scale value of 107, a surface area of 13 square meters per gram, an electron micrograph particle diameter of 180. millimicrons and an oil absorption value of 38 pounds of oil per 100 pounds of carbon black. The difference, if any, between the surface area values obtained on a carbon black sample by BET technique and by means of the "t curve method" i ' provides a measure of the extent of porosity in the carbon black . . : .

The invention will be more readily understood by reference to the following examples which describe the detailed preparation of representative compounds.

There are, of course, many other forms of this invention which will become obvious to one skilled in the art, once the invention has been fully disclosed, and it will accordingly be recognized that these examples are given for the purpose of illustration only, and are not to be construed as limiting the scope of this invention in any • «..·. way .

Example 1 In this example, there is employed a suitable / reaction apparatus provided with means. for supplying the combustion gas-producing reactants, i.e. a fuel and an oxidant, stream, either as separate streams or as precombusted gaseous reaction products, and also means for supplying the carbon black-yielding hydrocarbon feedstock to the apparatus. The apparatus may be provided with a refractory insulation or surrounded by means for cooling with a recirculating liquid which is preferably water. Additionally, the reaction apparatus is equipped. with temperature and pressure recording means, means for quenching the carbon black-formin reaction such as spray nozzles, means for. cooling the resultant carbon black product and means for separating and recovering the carbon black from other undesired by-products. Accordingly, in carrying out the' present process . ■ for preparing this class of novel active carbon blacks, the following procedure is employed. In order to obtain the desired flame, there are charged into a combustion zone of the apparatus through one or more inlets oxygen at a rate of 2000 SCFH 9τ)ό nai-vvdl gas g 'vate of .625 SCFH thereby generating a stream of combustion gases flowing, in a down- stream directioni at a high linear velocity. In a preferred embodiment of the present invention, however, the rapidly flow¬ ing stream of combustion gases is passed through a constricted or tapered portion of the apparatus having a fixed cross section or throat such as a conventional ventur'i throat in order to increase the linear velocity of the stream of 'combustion gases.

There is then introduced into the resul ant stream of hot com¬ bustion gases a carbon black-yielding hydrocarbon feedstock through one or more passages or inlets located peripherally to the stream of combustion gases 'at a rate of 1 .1 gallons which is a- 1% by weight, a hydrogen content of 7.9% by weight, a sulfur . content of 1.3% by weight , a hydrogen to carbon ratio of 1.04, a B.M. C. I.

Correlation Index of.133, a specific gravity in accordance with ASTM D-287 of 1.09, an API gravity in accordance with ASTM D-287 of -2.6, an SSU viscosity (ASTM D-S8) at 130°F. of 350, an SSU viscosity (ASTM D-88) at 2lO°F. of 58 and an as'phaltenes content of 5.7 percent. The reaction conditions used in this instance are such as to provide an overall combustion of 30.1 percent. The carbon black-forming reaction is then quenched with wate in a separate zone downstream of the reaction zone and the resultant carbon black-containing gases are subjected to the conventional steps of cooling, separation and recovery of the carbon black product. The carbon black product thus obtained is characterized by having a carbon' monoxide content of l.;54 millimoles/gm. , a BET total surface area of I30"m¾/gin, a "t curve" area of 130 m2/gm, a ratio of BET area to "t" area of 1.0, an activity factor of 200, and a D3P value.' of 151. Other characteristics of the resultant black product include a Nigro eter scale reading of 80. which value represents the relative amount of light reflected compared to a standard black dispersion in oil, a tinting strength of 247 which value represents the relative covering power of a carbon black when incorporated one part in thirty parts and compared to a series of standard reference blacks tested under similar conditions. . .

Exam le 2 In accordance with the. procedure of Example 1, oxygen at a rate of 2000 SCFH and natural gas at a rate of 625 SCFH are fed into the combustion zone of the reaction apparatus. To the resultant downstream flow off hot combus- . tion gases there is charged Sunray DX hydrocarbon feedstock at a rate of 16.9 gallons per hour. Prior to adding the feed stock, potassium chloride is added to the stream of hot com ■ bustion gases in small amounts. The reaction is carried out . at an overall combustion of 28.9 percent. There is obtained a carbon black product having a carbon monoxide content of 0¾."51 millimoles/gm, a BET total surface area of 122 m2/gm, a "t curve" surface area of 122 m2/gm, a ratio of "t" area to BET area of 1.0, an activity factor of 62.2 and a DBP value o 12.9. .In addition, the carbon black product possesses a Nigrometer scale reading of 80.5, a tinting strength of 242, and an extract value' of 0.29 percent by weight which is the amount of matter removed from the carbon black by refluxing a sample ©f the black in ten times its weight of benzene for a .12 to 22 hour period. . · ·· Example 3 Following the procedure of Example 1, there are a rate of 2 000 SCFH and natural gas at a rate of 625 SCFH in order to produce the desired flame. Into the flow. of hot combustion gases emanating from the combustion zone, there is then charged, as the hydrocarbon feedstock, Sunray DX at a rate of 1 6. 74 gallons per hour. Following the reaction period which is sufficient to provide an overall combustion of 29 . 2 percent, quenching of the reaction is completed and the carbon black product is cooled, separated and recovered. ..The resultant novel active carbon black produced hereby is characterized by havin a carbon monoxide content of 0 . 65 millimoles/gm, a BET total surface area of 1 25 m2/gm, a "t curve" area of.1 2 5 m2/gm, a ratio of "t" .area to BET total area of 1 . 0 , an activity factor of 8 1 . 3 and a DB value or i ^ . it has tualicruu- c uctii determined that the carbon black product possesses a Nigrometer scale .value of 82 , a tinting strength of 255 , and an extract value of 0. 32 percent.

Example 4 According to the procedure of Example 1 , oxygen at a rate of .2 00 0 SCFH .and natural gas at a rate of 625 SCFH are fed into the combustion zone of the reaction apparatus until the desired flame is produced. To the downstream-flow of hot gaseous products of the combus ion ' reaction there is introduced a hydrocarbon feedstock in vapor, form at a rate of 1 5 . 95 gallons per hour. The hydrocarbon feedstock utilized is Sunray DX as overall combustion of 30.3 percent. The resultant active carbon black product is characterized by having a carbon monoxide content of 0.60 millimoles/gm, a BET total surface area of 233 m2 /gm a "t curve" area of '181 m2/gm, a ratio of "t" area to BET total area of 0.8, an activity factor of 108.6 and a DBP value of 165. Additionally, the carbon black product has a Nigrometer scale value of 76 arid an extract value of 0.1 percent.

To a suitable reac described in Example 1 , there are charged a stream of oxygen at a. rate of 2000 SCFH and a stream of natural gas at a rate of 625 SCFH. -■ Having produced the desired flame, the hot combustion gases produced therein are passed in a downstream direction through ' a. portion of the apparatus which is restricted or tapered b^ .means of a conventional venturi throat so as to accelerate the linear velocity of the stream of combustion gases. Subsequently, .there is charged into the fast-flowing stream of combustion gases a stream of Sunray DX hydrocarbon feedstock at a rate of 16. gallons per hour. As an additive potassium chloride is added in small quantities and the reaction conditions are maintained so .as to result ui'an overall combustion of 30 percent. Thereafter, the carbon black producing reaction is quenched with a • spray of water 'and the carbon black is separated and recovered in conventional fashion. The active carbon black product thus of 0.69 millimoles/gm, a BET total surface^ area of 143 m2/gm, a "t curve" area of 138 m2/gm, a ratio of "t" area to BET total area of 0.97, an activity facto of 98.7 and a DBP value of 163.

The carbon product is further defined by. having a Nigrometer scale reading of 80.5, a' tinting strength of 257 and an extract value of 0.12 percent. -: Example . ■·; ' In accordance with the procedure of Example 1 , a suitable reaction apparatus is charged with oxygen at a rate of 2010 SCFH and a stream of natural gas at a rate of 620 SCFH in order to achieve the desired flame. Into the rapidly-moving stream of combustion gases issuing forth from the combustion zone there is fed as a hydrocarbon feedstock Sunray DX at a rate of 14.9 "gallons per hour. The reaction is carried out at an overall combustion of 31.2 percent and the carbon black product resulting therefrom is recovered as shown earlier. The active carbon black recovered has a carbon monoxide content of 0.57 millimoles/gm, a BET total surface area of 189 m2/gm, a "t curve" area of 157 m2/gm, a ratio of "t" area to BET area of 0.83, an activity factor of 89.5 and a DBP value of 151. The active carbon black product is further possessed of a "Nigrometer scale value of 80 and a tinting strength of 255.

- . * ■· · Exa.Tij)_lc_ ·. _ ■ · " • Into a suitable reaction apparatus as described in producing reactants as well as carbon black-yielding feedstocks, means for the recordation of temperatures and pressures, means for quenching the carbon black-forming reaction, means for cooling the resultant carbon black product and means for separating the carbon black from undesirable reaction by-products there are charged into the combustion zone thereof through at least one inlet oxygen at a rate of 1975 SCFH and natural gas at a rate of 625 SCFH until .the desired flame is obtained and a stream of hot combustion gases are flowing in a downstream direction at a high linear velocity. There is then introduced into the resultant stream of hot combustion gases a carbon black-yielding hydrocarbon feedstock, Sunray DX in this instance through one or more passages or inlets located peripherally uo the stream of combustion gases at a rate of 14.8 gallons per hour. . The. reaction conditions are maintained so as to provide a combustion of 30.8 percent. ' The carbon black-forming reaction is then quenched with water in a separate zone downstream of the reaction zona and the resultant carbon black-containing gases are subjected to the conventional cooling procedure followed by separation and recovery of the carbon black product. The carbon black obtained in this manner is characterized by having a carbon monoxide content of 0.37 millimoles/gm, a BET total surface area of 216 m2/gm, a "t curve" area of 1 4 rn2/gm, a ratio of BET area to "t" area of 0.81, an activity factor of 64.4 and a product has a Nigrometer scale reading of 81 and a tinting strength of .280. , . " ' • The rubber compositions of this invention are readily prepared by conventional mechanical methods. For example, the rubber and the active carbon black reinforcing agent are intim¬ ately admixed together on a conventional mixing machine of the ' -type normally used for mixing rubber or plastics such as a roll ·. ' . f · mill or a Banbury mixer in order to insure efficient dispersion.

The rubber compositions are compounded according' to standard industry formulations for both natural rubber and synthetic rubber-containing formulations. The resulting vulcanizates to be tested are cured at 293°F for 30 minutes when natural rubber is used and for 50 minutes when a synthetic rubber, styrene- butadiene rubber in this instance, is employed. In evaluating the performance of the novel active carbon blacks of the present -invention, the following formulations' are utilized wherein the quantities are specified in parts by weight.

Natural Rubber Synthetic Rubber- Synthetic Rubber Ingredient- "' ____Recip_e Recipe._No._ 1 _j_^i£^N°-_JL Polymer 100 (Natural 100 (styrene- 89.38 (styrene- Rubber) butadiene) butadiene) (cis-4 poly- , _ butadiene) Zinc Oxide 5 3 3 Sulfur 2.5 1.75 1.75 Stearic Acid 3 1.5 ,.'. 2 Flexamina ·, 1 ' " ■ ■ '. ... · , _ _ . . _ __ . _ - ~ Softener Mix - . 8 ' . -. . ·- Santocure (CBS),,. - . 1.25 1.4 Altax (MBTS) · 0..6 - · Sundex 790 ·. - ... - · 25.62 Wingstay 100 - ... : 2 Sunproof .' Improved - - 2.5 Carbon Black ' 50 50 ., 75 •With regard to the foregoing formulations, the Softener Mix comprises equal portions of naphthenic oil sold under the trade · designation Circosol 42XH by Sun Oil Company and a satur¬ ated polymeric petroleum hydrocarbon sold under the trade name j . . .

Paraplex by C. P. Hall Company. Altax (MBTS) is the trade name of R. T. Vanderbilt Company for mercaptobenzothiazy 1 disulfide accelerator. Flexamine is the trade designation of an anti¬ oxidant sold by U. S. Rubber Company. Santocure (CBS) is the trade designation for N-cyclohexyl-2-benzothiazole-sulfenamide, •a curing agent for rubber systems. Sundex 790 is the trade name for a plasticizer sold by Sun Oil Company. Sunproof Improved is the trade name for a.a antiozonant sold by Uniroyal Chemical Company. Wingstay 100 is the trade name for a stabilizer com¬ prising mixed diary 1-p-phenylene diamines sold by Goodyear Tire and Rubber Company.' ..

In the following examples there is demonstrated the advantageous and unexpected results achieved by the use of the . in rubber formulations.. It will, of course, be apparent that the examples, while being illustrative of the present invention, should not be construed as limiting or restrictive in any way.

One hundred parts by weight of a copolymer of 23.5 parts styrene and 76.5 parts butadiene, 1.5 parts by weight of stearic acid, 3 parts by weight of zinc oxide', 8 parts by weight of sof ene ' mix, 1.75 parts by weight of sulfur, 1.0 parts by weight of Flexamine, 1.25 parts by weight of Santocure (CBS) and 50 parts by weight of- the carbon black .product described in Example 1 are mixed on a mill roll to a homogeneous blend. The carbon black utilized has an activity factor of 200, a ratio of "t" curve surface area to BET surface area of 1.0 and a DBP absorption value of 151. The resulting compound is then cured •.at 293°F for a period of 50 minutes. Testing of the blend for conventional rubber properties reveals a value for Mooney viscosity ML-4' at 212°F of 92, a Mooney Scorch T5/T10 of 24.5/ 26.5, an extrusion shrinkage of 44.6% at 122°F, a tensile strength of 3350 p.s.i., a 300% modulus of 1980 p.s.i., an elongation of 470%, a Shore, hardness of 68, a bound rubber value of 31.7%, and a tear resistance of 312 lbs. /inch of thickness. Furthermore, using the Goodrich Flexometer wherein the oven is maintiined at temperature of 2l2°F, the stroke is m nu es, s e erm ne a e s a c compress on s Ί1.1%, the dynamic compression is 10.8%, and the permanent set is 17.1 percent." • Exa le 9 .. · On a conventional roll mill there are mixed to a homogeneous blend 100 parts by weight of natural rubber, 5 parts by weight of zinc oxide, 3 parts by weight of stearic . . . . . · acid , 2.5 parts by weight of sulfur, 0.6 parts by weight of mercaptobenzothiazy1 disulfide (MBTS) and 50 parts by weight of the carbon black prepared in accordance with Example' 1.

The resulting compound is subsequently cured at 293°F for a period of 30 minutes. A determination of properties of the vulcanizate gives a value of 72 for Mooney viscosity ML-4 ' at 212°F, a Mooney Scorch value T5/T10 of.17/18.5, a tensile Strength of 3600 p.s.i., a 300% modulus of 2130 p.s.i. , an elongation of 460%, a Shore hardness of 67, a tear resistance of 406 lbs. /inch of thickness and an Akron angle abrasion volume index of 316. Utilizing the Goodrich Flexometer as shown in Example 7, there are obtained a static compression value of 10.77o, a dynamic compression value of 13.1% and a permanent set value of 16.8 percent.

• Example 10 " ·· ' Following the procedure of Exav.ple 8 and substitutin for the carbon black employed therein 50 parts by weight of the The carbon black utilized herein is characterized by having an activity^ factor of 1 08. 6 , a ratio of "t" area to BET area of 0. 8 and a DBP absorption value of 1 65. Evaluation of results obtained on this vulcanizate reveals a value for tensile strength of 3970 p.s.i'., a 300% modulus of 1 800 p.s.i., an elongation of 495 percent and an Akron angle abrasion volume index of 1 91 . ' .Example lln '. ;' · ' .' Following' the procedure of Example 8 and using in lieu of the carbon black employed therein 50 parts by weight of the carbon black'produced in Example 6 , there is prepared, a cured rubber' vulcanizate. The results obtaiied on this rubber vulcanizate show a value for tensile strength of . 3855 p.s.i., a 3007o modulus of 1 735 p.s.i., an elongation of 5 0 -percent and an Akron angle abrasion volume index of 1 93.

Exam le I 2 Following the procedure of Example 8 and substituting for the carbon black employed therein 50 parts by weight of the carbon black of Example 7 , a cured vulcanizate is •'prepared.

The carbon black utilized herein is characterized by having an activity factor of 64 . 4 , a ratio of "t" curve surface area to BET surface area of 0. 8 1 and a DBP absorption value of 1 29.

There is obtained pa this sample a tensile strength of 4 1 30 percent and an Akron volume index of 171. .

' In this example there is utilized for rubber evalua- tion purposes a second synthetic rubber recipe. In particular, there are mixed on a Banbury mixer at 150 rpm to a homogeneous blend 89.38 parts by weight of a copolymer of 23.5 parts styrene • - and 76.5 parts butadiene, 35 parts by weight of cis-4 poly- butadiene rubber, 25.62 parts by weight of Sundex 790 plasti- ciz.er, 3 parts by weight of zinc oxide, 2.5 parts by weight of • Sunproof Improved an iozonant, 2 parts by weight of Wingstay 100 stabilizer, 2 parts by weight of stearic acid, 1.75 parts by weight of sulfur, 1.4 parts by weight of Santocure and 75 parts by weight of the carbon black of Example 2, The carbon black of Example 2 is characterized by having an activity factor • of 62.2, a ratio of nt" area to BET area of' 1.0 and a DBP absorption value of 129. A determination of test measurements on the .' vulcanizate . cured at 293°F for 60 minutes reveals a Mooney viscosity of 47, a Mooney Scorch T5/TI0 of 20.5/22.5, an extrusion shrinkage of 39.9%, a tensile strength of 2790 p.s.i., a 300% modulus of 1090 p.s.i., an elongation of 570%, a Shore hardness of 58 and, utilizing the Goodrich Flexometer, a static compression of 25.6%, a dynamic compression of 5.5% and a permanent set of 10.7 percent. . . y the carbon black used therein a carbon black as prepared in Example 3 which'- -has an activity factor of .81.3, a ratio of "t" area to BET area of 1.0 and a DBP absorption value of 139, there is obtained a cured rubber vulcanizate. The results obtained on this vulcanizate show a Mooney viscosity of 49, a Mooney .Scorch T5/T10 of 19/21, an extrusion shrinkage of 35.4%, a tensile strength of 2840 p.s.i. , a 300% modulus 'of 1260 p.s.i. an elongation of 530%, a Shore hardness of 59, and, in accordance with measurements on the Goodrich Flexometer , a static compression of 23.5%, :a dynamic compression of 6.270 and a permanent set of 12 percent. ...

Example 15_ .Following the procedure of Example 13 and substituting for the carbon black employed therein a carbon black of Example 4 having an activity factor of 108.6, a ratio of "t" area to BET area of 0.8 and a DBP value of 165, there is obtained a cured rubber vulcanizate. The vulcanizate possesses a Mooney viscosity ML-41 at 212°F of 67, a Mooney Scorch T5/T10 of 18/ , an extrusion shrinkage of 37.4%, a tensile strength of 2830 p.s.i., a 300% modulus of 1030 p.s.i.., an elongation of 590%,, a Shore hardness of 58 and an Akron angle abrasion volume index of 218. ..'·. .- . ' '·· A cured rubber vulcanizate is .produced according to Example 13 with the exception that, for the carbon black utilized therein, 75 parts by weight of carbon black manufactured as described in Example 5 is employed herein. The carbon black of Example 5 possesses an activity factor of 98*7, a ratio of "t" area to BET area of 0.97 and a DBP absorption value of 163. Measurements on this vulcanizate reveal a Mooney viscosity of 48, a Mooney Scorch Τ5/ΤΓ0 of 19/21, an extrusion shrinkage of 40.7%, a tensile strength'of 2910 p.s.i. a 30.0% modulus of 1060 p.s.i. ,. an elongation of 580%, a Shore hardness of 59 and, utilizing the Goodrich Flexo eter, a static compression of 24.1%, a dynamic compression of 4.8% and a permanent set of 10.3 percent.

• · .. ·" ' · .. Example 17 ' · ; ' •In accordance with the procedure of Example 13 and using, in lieu of the carbon black employed therein, 75 parts by weight. of the carbon black prepared as described in Example 6," a cured rubber vulcanizate is prepared. The carbon black employed herein is characterized by having an activity factor of 89.5, a ratio of "t" area to BET area of 0.83 and a DBP absorption value of 151 milliliters of dibutyl phthalate absorbed par 100 grams of carbon black. The results obtained on this vulcanizate give a value for Mooney viscosity ML-4 ' shrinkage of 32.7%, a tensile strength of 2740 p.s.i., a 300 ; modulus of 820 p.s.i. , an elongation of 660%, a Shore hardness . of 55 and an Akron angle abrasion volume index of 212. Deter- minations performed on the Goodrich Flexomater show a static compression of 27.4%, a dynamic compression of 8.8% and a , permanent set of 15.5 percent.

. Example 18^ Following the procedure of Example' 13 and substituting for the carbon black used therein 75 parts by weight of the car- '■ bon black of Example 7 having an activity factor of 64,4, a . ratio of "t" area ta BET area of .0.81 and a DBP absorption value, of 129, there is prepared a cured rubber vulcanizate. Test measurements on this sample reveal a Mooney viscosity ML- 1 at t2l2°F of 64, a Mooney Scorch T5/T10 of 22/24.5, an extrusion- . shrinkage of 37.'9%, a tensile strength of 3040 p.s.i., a 300% modulus of 760 p.s.i., an elongation of 680%, a Shore hardness • of 60 and, utilizing the Goodrich Flexometer, a static compression of 26.4%, a dynamic compression of 11.2% and a perm- anent set of 18.3 percent. - ■ Exam le I 9 Utilizing the procedure of Example 1 , there are fed into the combustion zone of the reaction apparatus oxygen at - a rate of.2000 SCFH and natural gas at a rate of 625 SCFH so .the flowing combustion gases there is then introduced Sunray DX hydrocarbon .feedstock at a rate of 17. 7 gallons per hour and potassium chloride in relatively small amounts. The reaction is carried out at an overall combustion of 29.8 percent. There is obtained a carbon black product having a carbon monoxide content of 0.45 millimoles/gm, a BET total surface area of 150 m2 /gm a "t curve" surface area of 144 m2/gm, a ratio of "t" area to BET area of 0.92 , an activity factor of 64.8 and a DBP value of 119. Moreover, the carbon black product is characterized further by having a Nigrometer scale value of 81 , a tinting strength of 262 and an extract value of 0. 03 percent.

Fifty parts by weight of the carbon black of Example 19 are then incorporated in the rubber rormuiaiziuu as aiiww.i Ι.Ί Example 8 to produce a rubber compositio .which is cured at a temperature of 2?3°F for a period of 60 minutes." The resulting, rubber vulcanize is found to have an extrusion shrinkage of 33.5%, a tensile strength of 4045 p.s.i. , a 300% modulus of 1905 p.s.i. , an elongation of 490%, a Shore hardness of 69 and an Akron angle abrasion volume index of 156. It is also found, utilizing the Goodrich Flexomster, that the rubber compound has a static compression-of 18.4%, -a dynamic compression of 2.8% and a permanent set of 5.0 percent.

Seventy-five parts' by weight of the carbon black product of E>cample .19 are incorporated in a rubber formulation is cured at 293°F for 60 minutes. Results on this sample reveal .a tensile strength of 3130 p.s.i. , a 300% modulus of 785 p.s.i., an elongation of 675%, a Shore hardness of 60 and an Akron angle abrasion volume index of.235.

It will become readily apparent from the foregoing results that the novel group of active carbon black products disclosed herein impart to natural and . synthetic rubber com-positions extremely desirable properties and therefore constitute a valuable group of effective reinforcing carbon blacks for rubber systems. For example, it V7ill be noted that the present novel and important class of active carbon blacks are effective in imparting to rubber compositions properties such as abras'ion resistance, modulus, extrusion shrinkage and/or activity. Additionally, it is found that while these properties are achieved, other desirable processing characteristics of the compositions of the present invention are not unduly affected by the incorporation of the active carbon blacks in the compositions of this invention. ·;.. . . .

Numerous chemical- curing systems have been found useful in promoting the "interaction of the active carbon black reinforcement and the natural or synthetic . rubber in- practicing the present invention. Exemplary of the chemical curing agents are mercaptobenzotbi.azy 1 disulfide (MBTS) , N-cyclohexy 1-2-benzothiazole-sulfonamide, and tetramethy l hiuramdisulfi.de with other conventional rubber additives. Illustrative of such, additives are other reinforcing agents such as titanium dioxide, silicon dioxide, zinc oxide, calcium carbonate, clays, calcium silicate, zinc sulfide, hydrous alumina and calcined magnesia; thermoplastic resins such as polyvinyl chloride and epoxy resins as compounding substances; vulcanizing agents; vulcanization accelerators; accelerator activators, sulfur curatives; anti- oxidants; de'celerators ; heat stabilizers; plasticizers , softeners or extender oils such as mineral oil, resins, fats, waxes, petroleum distillates, vegetable oils, e.g., linseed oil and soybean oil, butyl cellosolve pelargonate, di-n-hexyl fldi fl e . trioctyl phosphate, chlorinated hydrocarbons, ether, ketones, terpenes, gum turpentine, rosin, pine tar, coal tar products including alkyl naphthalenes and polynuclear aromatics '.and liquid polymers of conjugated dienes; and the like. It will be apparen that compositions containing such other additives .are within the scope' of- his invention. Moreover, it is further apparent from the foregoing data that the use in rubber of the present carbo black products having very high activity factors, virtual non-porosity' and DBP absorption values greater than 110, result in reinforced rubbar compositions having extremely desirable physical properties.

* · ·■ * ■ . ' While this invention has been described with respect un erstoo t at var at ons an mo cat on's t ereo may be miade- hich are obvious to those skilled in the art without departing' from the spirit or scope of the invention.

Claims (1)

1. 5. A composition of matter comprising a rubber siected from the group consisting of natural and synthetic rubbers and a carbon black product selected from the group consisting of carbon blacks characterized by having an activity factor, which is the numerical product of the specific surface area in square meters per gram of the carbon black and the carbon monoxide content in millimoles per gram of the carbon black of at least 62, a value for the ratio of non-porous specific surface area of the carbon black to total specific surface area of the carbon black which is at least 0.8 and a DBP absorption value of at least 110 milliliters of dibutyl phthalate absorbed per 100 grams of carbon black, wherein the carbon black produce is present in amounts, of from about 10 to about 250 parts by weight per 100 parts by weight of rubber. 6. A composition as defined in Claim 5 wherein the rubber is natural rubber. 7. A composition as defined in Claim 5 wherein the rubber is synthetic rubber. 8. A process for preparing a rubber composi- .. tion having improved properties which comprises mixing a rubber selected from the group consisting of natural and synthetic rubbers with a carbon black product selected from the group consisting of carbon blacks characterized by having an activity factor, which is the numerical product of the specific surface area in square meters per gram of the carbon black and the carbon monoxide content in millimoles per gram of the carbon black of at least 62, a value for the ratio of non-porous specific surface area of the carbon black to total specific surface area of the carbon black which is at least 0.8 and a DBF absorption value of at least 100 milliliters of dibutyl phthalate absorbed per 100 grams of carbon black, said carbon black product being present in amounts of from about 10 to about 250 parts by weight per 100 parts by weight of rubber, and vulcanizing the mixture . ,'··. " .'. . .-" ' .' 9. A process as defined as Claim 8 wherein the carbon black product is present in amounts of from about 20 to about 100 parts by weight per 100 parts by weight of rubber. 10. A process as defined in Claim 8 wherein the carbon black product is present in amounts of from about 40 to about 80 parts by weight per 100 parts by-weight of rubber.