Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK  ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
  • C09C1/00—Treatment of specific inorganic materials other than fibrous fillers; Preparation of carbon black
  • C09C1/28—Compounds of silicon
  • C09C1/30—Silicic acid
  • C09C1/3081—Treatment with organo-silicon compounds
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K9/00—Use of pretreated ingredients
  • C08K9/04—Ingredients treated with organic substances
  • C08K9/06—Ingredients treated with organic substances with silicon-containing compounds
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK  ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
  • C09C3/00—Treatment in general of inorganic materials, other than fibrous fillers, to enhance their pigmenting or filling properties
  • C09C3/08—Treatment with low-molecular-weight non-polymer organic compounds
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK  ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
  • C09C3/00—Treatment in general of inorganic materials, other than fibrous fillers, to enhance their pigmenting or filling properties
  • C09C3/12—Treatment with organosilicon compounds

Definitions

• the present invention relates to methods for making chemically modified fillers. More particularly, this invention relates to processes for producing particulate or amorphous fillers having at least reduced or minimum carbon and mercapto contents, an at least reduced or minimum Silane Conversion Index, and an at least reduced or minimum Standard Reinforcement Index. Further, this invention relates to processes for producing particulate or amorphous fillers having at least reduced or minimum carbon and sulfur contents, at least reduced or minimum Silane Conversion Index, and at least reduced or minimum Standard Tensile Stress @ 300% elongation.
• this invention relates to a process for producing a hydrophobized and functionalized filler, hereinafter referred to as a "modified filler” , that improves the efficiency of producing polymeric compositions, such as in rubber compounding, and the performance of polymerized or cured products, such as but not limited to tires .
• silica filler is used to impart improved tensile strength, tear resistance and abrasion resistance to the rubber vulcanizate.
• Silica fillers are also used in combination with carbon blacks to obtain maximum mileage in passenger vehicle tires and off-the- road tires, e.g., tires for mining and logging operations and for road-building equipment. Such applications have become well established.
• silica fillers that are not well dispersed and/or coupled in the rubber do not provide the overall improved performance obtained by the use of carbon blacks alone. This is observed most readily in rubber vulcanizates used for tires, e.g., tire treads.
• alkoxysilanes as coupling agents for silica fillers are drawbacks.
• hydrolysis of the alkoxy group(s) results in the release of alcohol some of which is retained in the surrounding elastomer matrix.
• the portion of the alcohol retained in the surrounding elastomer matrix can result in porous zones or blisters which can form surface defects in the resulting formed rubber article and/or can impair the dimensional stability of treads during extrusion and tire building.
• This evolution and off-gassing of alcohol continues through the life of a product manufactured from an elastomer compounded with alkoxysilane coupling agents.
• Bis (alkoxysilylalkyl) -polysulfides can be used in place of mercaptoalkyltrialkoxysilanes.
• Preparation of silica- filled rubber compositions using bis (alkoxysilylalkyl) - polysulfides generally need to be performed within narrow temperature operating ranges.
• the mixing temperature should to be high enough for the silica-silane reaction to take place rapidly but low enough to avoid an irreversible thermal degradation of the polysulfane function of the coupling agent and premature curing (scorch) of the rubber mixture.
• an improved modified filler e.g., a particulate or amorphous inorganic oxide, that is characterized by a carbon content of greater than 1 wt . %, a mercapto content of greater than 0.15 wt. %, a Silane Conversion Index (described hereinafter) of at least 0.3, and a Standard Reinforcement Index (also described hereinafter) of 4 or more can be prepared.
• an improved filler e.g., a particulate or amorphous inorganic oxide, that is characterized by a carbon content of greater than 1 wt . %, a sulfur content of greater than 0.1 wt.
• the modified filler of the present invention can be produced by utilizing a certain combination of functionalizing and hydrophobizing agents in an aqueous suspension of inorganic oxide having a pH of 2.5 or less and treating the acidic aqueous suspension of modified fillers with acid neutralizing agents to increase the pH of the suspension to a range of from 3.0 to 10.
• a functionalizing agent is a reactive chemical which can cause an inorganic oxide to be covalently bonded to the polymeric composition in which it is used.
• a hydrophobizing agent is a chemical which can bind to and/or be associated with an inorganic oxide to the extent that it causes a reduction in the affinity for water of the inorganic oxide while increasing the inorganic oxide's affinity for the organic polymeric composition in which it is used.
• the aforementioned Standard Tensile Stress @ 300% elongation indicates improved reinforcement of the rubber composition. Improved reinforcement translates into an improvement in the mechanical durability of the product which is evidenced by increased tear strength, hardness and abrasion resistance.
• the modified filler has the benefit of requiring less time and energy to get incorporated into the polymeric composition.
• the aforementioned Standard Reinforcement Index (SRI) of at least 4 or greater indicates a modification of the interaction or bonding between the components of the filler- polymer composition. Specifically, there is a stronger interaction between the filler and polymer and/or the polymer and polymer than usually present for a given amount of interaction between filler and filler. Alternatively stated, there is a weaker interaction between the filler and filler than usually present for a given amount of interaction between filler and polymer and/or polymer and polymer. Appropriate modifications of these interactions in a rubber composition have been reported to result in better tire performance, e.g., improved treadwear life, lower rolling resistance, better traction on snow and lower noise generation. In addition to the improved properties, the modified filler has the benefit of requiring less time and energy to get incorporated into the polymeric composition.
• FIG. 1 is a graph of the cure profile for compositions of Example 17.
• FIG. 2 is a graph of the cure profile for comparative compositions of Example 17.
• the modified filler of the present invention can be produced by any method that results in such a filler, i.e., an inorganic oxide, having a carbon content of greater than 1 wt . %, or at least 1.5 wt . %, or at least 2.0 wt. %; a mercapto content of greater than 0.15 wt. %, or at least 0.3 wt. %, or at least 0.5 wt. %; a Silane Conversion Index, of at least 0.3, or at least 0.4, or at least 0.5 and a Standard Reinforcement Index of at least 4.0, or at least 4.5, or at least 5.0.
• a filler i.e., an inorganic oxide, having a carbon content of greater than 1 wt . %, or at least 1.5 wt . %, or at least 2.0 wt. %; a mercapto content of greater than 0.15 wt. %, or at least 0.3 wt
• the modified filler of the present invention can also be characterized by a Tensile Stress at 300% elongation of at least 6.2, or at least 7.0, or at least 7.5, or at least 8.0. Further, the modified filler of the present invention can be produced by any method that results in a filler, i.e., an inorganic oxide, having a carbon content of greater than 1 wt. %, or at least 1.5 wt. %, or at least 2.0 wt. %; a sulfur content of greater than 0.1 wt . %, or at least 0.3 wt. %, or at least 0.6 wt.
• a filler i.e., an inorganic oxide
• the modified filler of the present invention can further be characterized by a Brunauer-Emmett- Teller (BET) single point surface area of from 20 to 350 m 2 /g, or from 40 to 300 m 2 /g, or from 100 to 200 m 2 /g, a pH of from 5 to 10, or from 5.5 to 9.5, or from 6.0 to 9.0, or a pH of from 6.5 to 7.5 or the pH of the product may range between any combination of these values, inclusive of the recited ranges; a Soxhlet Extractable percent carbon of less than 30 percent, or less than 25 percent, or less than 20 percent, e.g., 15 percent.
• BET Brunauer-Emmett- Teller
• Suitable fillers can include but are not limited to inorganic oxides selected from precipitated silica, colloidal silica or mixtures thereof.
• the inorganic oxide can be a material which is suitable for use in the various molding, compounding or coating processes including but not limited to injection molding, lamination, transfer molding, compression molding, rubber compounding, coating (such as dipping, brushing, knife coating, roller coating, silk screen coating, printing, spray coating and the like), casting, and the like.
• the inorganic oxide used to produce the modified filler of the present invention can be precipitated silica of the type commonly employed for compounding with rubber.
• Various commercially available silica materials can be used in this invention.
• the silica can include silica commercially available from PPG Industries under the Hi-SiI trademark with designations 210, 243, etc; silica available from Rhone-Poulenc, with, for example, designations of Z1165MP and Z165GR; and silica available from Degussa AG with, for example, designations VN2 and VN3, etc.
• the precipitated silica used to produce the modified filler of the present invention can be prepared by various methods known to one having ordinary skill in the art.
• the precipitated silica can be prepared by acidic precipitation from solutions of silicates, e.g., sodium silicate.
• the method of preparing the precipitated silica can be selected based on the desired properties of the silica, such as surface area and particle size required for a given application.
• the BET surface area of the precipitated silica used in preparing the modified filler of the present invention will generally be within a range of from 50 m 2 /g to 1000 m 2 /g, or from 100 m 2 /g to 500 m 2 /g.
• the precipitated silica used to form the modified filler can be in the form of an aqueous suspension from production stages that precede the drying step, such as a slurry formed during precipitation or as a re-liquefied filter cake,- or the suspension can be formed by re-dispersing dried silica into an aqueous and/or organic solvent.
• concentration of hydrophilic precipitated silica in the aqueous and/or organic suspension is not critical and can be within a range of from 1 to 90 wt . %, or, the concentration of hydrophilic precipitated silica can be within a range of from 1 to 50 wt. %, or from 1 to 20 wt. %.
• the Silane Conversion Index can be defined by the equation TV(T 1 + T 2 + T 3 ) .
• the values for T 1 , T 2 and T 3 can be determined by solid state 29 Si NMR and represent reacted silane units.
• the Silane Conversion Index can provide an indication of the degree of reaction or crosslinking of the silanes on adjacent Si atoms and with each other. In general, the higher the index number, the greater the amount of crosslinking amongst the silane, silica surface and adjacent silanes.
• T 1 represents a silane unit chemically bonded at one site to either the silica surface or another silane.
• T 2 represents a silane unit chemically bonded at two sites to either a Si atom on the silica surface and to one adjacent silane, two adjacent silanes or to two adjacent surface Si atoms, i.e., partially crosslinking structures.
• T 3 represents a silane unit chemically bonded at three sites to either a Si atom on the silica surface and two adjacent silanes, two Si atoms and one silane or three silane units .
• Organometallic Reactant Conversion Index comparable to the Silane Conversion Index, can be developed and used by those skilled in the coupling agent art to provide an indication of the degree of reaction or crosslinking of zirconates and/or titanates (alone or in combination with silanes) with the inorganic oxide and themselves .
• the Standard Reinforcement Index can be determined using a Standard Compounding Protocol.
• the Standard Compounding Protocol described herein does not include the addition of free or unbounded coupling agents to the rubber batch. Typically, the addition of such coupling agents to a rubber batch can require more time for mixing by the compounder.
• the Standard Tensile Stress @ 300% elongation can be determined using a Standard Compounding Protocol .
• the Standard Compounding Protocol described herein does not include the addition of free or unbounded coupling agents to the rubber batch. Typically, the addition of such coupling agents to a rubber batch can require more time for mixing by the compounder.
• the organic polymeric compositions, e.g., plastics and/or resin, in which the modified filler can be present include essentially any organic plastic and/or resin. Included in this definition are rubber compounds. Such polymers are described in Kirk Othmer Encyclopedia of Chemical Technology, Fourth Edition, 1996, Volume 19, pp 881-904, which description is herein incorporated by reference.
• the modified filler can be admixed with the polymer or the polymerizable components thereof while the physical form of the polymer or polymerizable components is in any liquid or compoundable form such as a solution, suspension, latex, dispersion, and the like.
• the polymeric compositions containing the modified filler may be milled, mixed, molded and cured, by any manner known in the art, to form a polymeric article.
• the polymeric article can have dispensed therein from 10 to 150 parts per 100 parts polymer of modified filler.
• Suitable polymers can include but are not limited to thermoplastic and thermosetting resins, rubber compounds and other polymers having elastomeric properties.
• the polymers can include alkyd resins, oil modified alkyd resins, unsaturated polyesters, natural oils (e.g., linseed, tung, soybean), epoxides, nylons, thermoplastic polyester (e.g., polyethyleneterephthalate, polybutyleneterephthalate) , polycarbonates, i.e., thermoplastic and thermoset, polyethylenes, polybutylenes, polystyrenes, polypropylenes, ethylene propylene co- and terpolymers, acrylics (homopolymer and copolymers of acrylic acid, acrylates, mathacrylates, acrylamides, their salts, hydrohalides, etc.) , phenolic resins, polyoxymethylene (homopolymers and copolymers) , polyurethanes, polysulfones, polysulfide rubbers, nitrocelluloses, vinyl butyrates, vinyls (vinyl chloride and/or vinyl acetate containing poly
• the amount of modified filler that can be used in a polymeric composition can vary.
• the amount of modified filler can be from 5 up to 70 wt . %, based on the total weight of the plastic composition.
• the typical amount of modified filler used in ABS (acrylonitrile- butadiene-styrene) copolymer can be from 30 to 60 wt . %
• acrylonitrile-styrene-acrylate copolymer can be from 5 to 20 wt . %
• aliphatic polyketones can be from 15 to 30 wt . %
• alkyds resins for paints and inks
• thermoplastic olefins can be from 10 to 30 wt . %
• epoxy resins can be from 5 to 20 wt. %
• ethylene vinylacetate copolymer can be up to 60 wt. %
• ethylene ethyl acetate copolymer can be up to 80 wt. %
• liquid crystalline polymers (LCP) can be from 30 to 70 wt. %
• phenolic resins can be from 30 to 60 wt. % and in polyethylene the amount can be greater than 40 wt. %.
• the polymer can be an organic rubber.
• Non-limiting examples of such rubbers can include but are not limited to natural rubber; those formed from the homopolymerization of butadiene and its homologues and derivatives such as: cis-1,4-polyisoprene; 3 ,4-polyisoprene; cis- 1,4-polybutadiene; trans-1,4-polybutadiene; 1,2-polybutadiene; and those formed from the copolymerization of butadiene and its homologues and derivatives with one or more copolymerizable monomers containing ethylenic unsaturation such as styrene and its derivatives, vinyl-pyridine and its derivatives, acrylonitrile, isobutylene and alkyl-substituted acrylates such as methylmethacrylate.
• Non-limiting examples can include styrene-butadiene copolymer rubber composed of various percentages of styrene and butadiene and employing the various isomers of butadiene as desired (hereinafter "SBR"); terpolymers of styrene, isoprene and butadiene polymers, and their various isomers; acrylonitrile-based copolymer and terpolymer rubber compositions; and isobutylene-based rubber compositions; or a mixture thereof, as described in, for example, United States Patent Nos . 4,530,959; 4,616,065; 4,748,199; 4,866,131; 4,894,420; 4,925,894; 5,082,901; and 5,162,409.
• SBR styrene-butadiene copolymer rubber composed of various percentages of styrene and butadiene and employing the various isomers of butadiene as desired
• SBR sty
• Non-limiting examples of suitable organic polymers can include copolymers of ethylene with other high alpha olefins such as propylene, butene-1 and pentene-1 and a diene monomer.
• the organic polymers can be block, random, or sequential and can be prepared by methods known in the art such as but not limited to emulsion (e.g. e-SBR) or solution polymerization processes (e.g., s-SBR) .
• Further non-limiting examples of polymers for use in the present invention can include those which are partially or fully functionalized including coupled or star-branched polymers.
• organic rubbers can include polychloroprene, chlorobutyl and bromobutyl rubber as well as brominated isobutylene-co-paramethylstyrene rubber.
• the organic rubber can be polybutadiene, s-SBR and mixtures thereof.
• the polymeric composition can be a curable rubber.
• curable rubber is intended to include natural rubber and its various raw and reclaimed forms as well as various synthetic rubbers.
• curable rubber can include combinations of SBR and butadiene rubber (BR) , SBR, BR and natural rubber and any other combinations of materials previously disclosed as organic rubbers.
• BR butadiene rubber
• the terms “rubber”, “elastomer” and “rubbery elastomer” can be used interchangeably, unless indicated “ ⁇ ⁇ otherwise.
• rubber composition “compounded rubber” . and “rubber compound” are used interchangeably to ' refer to rubber ' which has been blended or mixed with various ingredients and . materials, and such terms are well-known to those having skill in the rubber mixing or rubber compounding art .
• the modified filler of the present invention can be prepared using a variety of methods known to one having ordinary skill in the art.
• the modified filler can be prepared by using step A alone or both steps A and B for preparing hydrophobic silica and fumed silica as disclosed in U.S. Patent Nos. 5,908,660 and 5,919,298, respectively, which relevant disclosure is incorporated herein by reference, with the following changes.
• the amount of acid used results in a pH of 2.5 or less in the aqueous suspension, or, a pH of 2.0 or less, or, a pH of 1.0 or less, or a pH of 0.5 or less,- the modifying chemical used is a combination of mercaptoorganometallic reactant and a non-sulfur containing organometallic compound, which is referred to hereinafter as non- sulfur organometallic compound, in a weight ratio of the mercaptoorganometallic reactant to the non-sulfur organometallic compound of at least 0.05:1, or from 0.05:1 to 10:1, or from 0.1:1 to 5:1, or from 0.2:1 to 2:1, or from 0.5:1 to 1:1, or the weight ratio can range between any combination of these values, inclusive of the recited values; and after the chemical treatment reaction is completed, the acidity (either added or generated in situ by the hydrolysis of halogenated organometallic compounds) is neutralized.
• the pH of the resulting aqueous suspension is increased to a pH range of from 3 to 10.
• the neutralizing agents can be selected from a wide variety of such materials that are known in the art to increase the pH of an acidic solution.
• the neutralizing agent should be selected such that the properties of the modified filler are not adversely- affected.
• suitable neutralizing agents can include- but are not limited to sodium hydroxide, potassium hydroxide, ammonium hydroxide and sodium bicarbonate.
• neutralization of the modified filler can be accomplished by adding gaseous ammonia to the aqueous solution during spray drying.
• the acid used in step (A) can be selected from a wide variety of acids, including organic and/or inorganic.
• the acid catalyst can be inorganic.
• suitable acid catalysts can include but are not limited to hydrochloric acid, hydrobromic acid, hydroiodic acid, sulfuric acid, nitric acid, phosphoric acid, and benzenesulfonic acid.
• One acid catalyst or a mixture of two or more acid catalysts can be employed as desired.
• the catalytic amount of the acid can be generated in situ by hydrolysis of the chlorosilane or the reaction of the chlorosilane directly with hydroxyls of the inorganic oxide.
• step (A) The temperature at which step (A) is conducted is not critical and can be within the range of from 20 0 C to 250 0 C, although somewhat lesser or somewhat greater temperatures can be used when desired.
• the reaction temperature will depend on the reactants used, e.g., the organometallic compound(s), the acid and, if used, a co-solvent.
• step (A) is conducted at temperatures in the range of from 30 0 C to 150 0 C.
• step (A) can be conducted at the reflux temperature of the slurry used in step (A) .
• the modifying chemical or coupling agent can be a combination of functionalizing agent (s) in place of mercaptoorganometallic compound and hydrophobizing agent (s) in place of a non-sulfur organometallic compound.
• the combination of functionalizing and hydrophobizing agents can be used in the same weight ratios specified for the combination of mercaptoorganometallic compound to the non-sulfur organometallic compound.
• Non-limiting examples of reactive groups that the functionalizing agent can contain include, but are not limited to, vinyl, epoxy, glycidoxy and (meth) acryloxy.
• suitable materials can include, but are not limited to, chemicals such as natural or synthetic fats and oils and the non-sulfur organometallic compounds represented by chemical formulae II, III, IV, V and mixtures of such hydrophobizing agents.
• the initial step of contacting the acidic aqueous suspension of inorganic oxide with a combination of mercaptoorganometallic compound and non-sulfur organometallic compound, such as a non-sulfur organosilicon compound can further include adding a water miscible solvent in amounts sufficient to facilitate their reaction with the inorganic oxide.
• the solvent can act as a phase transfer agent speeding-up the interaction of the combination of hydrophobic sulfur and non- sulfur organometallic compounds with the hydrophilic inorganic oxide.
• the amount of the water- miscible organic solvent can comprise at least 5 wt . % of the aqueous suspension, or from 15 to 50 wt.
• wt . % or from 20 to 30 wt . % of the aqueous suspension, or the wt . % can vary between any combination of these values, inclusive of the recited values.
• suitable water-miscible solvents can include but are not limited to alcohols such as ethanol, isopropanol and tetrahydrofuran.
• isopropanol can be used as the water-miscible organic solvent.
• surfactant can be used in the initial step, either in combination with the water-miscible organic solvent or in place of the water-miscible organic solvent, in an amount sufficient to facilitate the chemical modification of the inorganic oxide by the mercaptoorganometallic compound and the non-sulfur compound.
• the surfactant can be selected from nonionic, anionic, cationic, amphoteric or a mixture of such surfactants .
• the surfactant can be selected such that it does not have an adverse effect on the performance of the resulting chemically modified inorganic oxide for its intended use.
• the surfactant when used, can be present in an amount of from 0.05 to 10 wt.
• % of the aqueous suspension or, from 0.1 to 5 wt . %, or from 0.1 to 3 wt . %, or the wt . % can vary between any combination of these values, inclusive of the recited values.
• Non-limiting examples of suitable surfactants can include but are not limited to alkylphenolpolyglycol ethers, e.g., p-octylphenolpolyethyleneglycol (20 units) ether, p-nonylphenolpolyethyleneglycol (20 units) ether, alkylpolyethyleneglycol ethers, e.g., dodecylpolyethyleneglycol (20 units) ether, polyglycols, e.g., polyethyleneglycol 2000, alkyltrimethylammonium salts, e.g., cetyltrimethylammonium chloride (or bromide), dialkyldimethylammonium salts, e.g., dilauryldimethylammonium chloride, alkylbenzyltrimethylammonium salts, alkylbenzenesulfonates, e.g., sodium p-dodecylbenzenesulfonate, sodium p-
• the mercaptoorganometallic compound used to produce the modified filler of the present invention can be represented by the following graphic formula I: Ah) n
• M can be silicon
• L can be halogen or -OR 7
• Q can be hydrogen, C x -C 12 alkyl, or halosubstituted Ci-C 12 alkyl
• R 6 can be C 1 -C 12 alkylene
• R 7 can be C 1 -C 12 alkyl or alkoxyalkyl containing from 2 to 12 carbon atoms, said halogen or (halo) groups being chloro, bromo, iodo or fluoro
• n can be 1, 2 or 3.
• R 6 can be C 1 -C 3 alkylene, e.g., methylene, ethylene, and propylene
• R 7 can be C 1 -C 4 alkyl, e.g., methyl and ethyl
• L can be -OR 6
• n can be 3.
• mercaptoorganometallic reactants having two mercapto groups can be used.
• mercaptoorganometallic compounds in which the mercapto group is blocked i.e., the mercapto hydrogen atom is replaced by another group
• the blocked mercaptoorganometallic compounds can have an unsaturated heteroatom or carbon bound directly to sulfur via a single bond.
• blocking groups can include but are not limited to thiocarboxylate ester, dithiocarbamate ester, thiosulfonate ester, thiosulfate ester, thiophosphate ester, thiophosphonate ester, thiophosphinate ester, etc.
• a deblocking agent when reaction of the mixture to couple the filler to the polymer is desired, can be present in the mixture to deblock the blocked mercaptoorganometallic compound.
• a catalyst e.g., tertiary amines, Lewis acids or thiols, can be used to initiate and promote the loss of the blocking group by hydrolysis or alcoholysis to liberate the corresponding mercaptoorganometallic compounds.
• Various procedures for preparing and using such compounds, e.g., blocked mercaptosilanes are known in the art, and can include those disclosed in PCT Application No. WO 99/09036, and U.S. Patent Nos. 3,692,812 and 3,922,436, which relevant portions are incorporated herein by reference.
• Non-limiting examples of suitable mercaptoorganometallic compound(s) can include but are not limited to mercaptomethyltrimethoxysilane, mercaptoethyltrimethoxysilane, mercaptopropyltrimethoxysilane, mercaptomethyltriethoxysilane, mercaptoethyltripropoxysilane, mercaptopropyltriethoxysilane, (mercaptomethyl) dimethylethoxysilane,
• the mercaptoorganometallic compound can include mercaptopropyltrimethoxysilane, mercaptopropyltriethoxysilane or mixtures thereof.
• Non-limiting examples of suitable blocked mercaptosilanes can include but are not limited to 2- triethoxysilyl-1-ethyl thioacetate, 3-trimethoxy-silyl-l-propyl thiooctoate, bis- (3-triethoxysilyl-l-propyl) - methyldithiophosphonate, 3-triethoxysiIyI-1- propyldimethylthiophosphinate, 3-triethoxysilyl-l- propylmethylthiosulfate, 3-triethoxysilyl-l- propyltoluenethiosulfonate and mixtures thereof.
• the modifying chemical or coupling agent can be a combination of functionalizing agent (s) in place of bis (alkoxysilylalkyl)polysulfide and hydrophobizing agent (s) in place of a non-sulfur organometallic compound.
• the combination of functionalizing and hydrophobizing agents can be used in the same weight ratios specified for the combination of bis (alkoxysilylalkyl)polysulfide to the non-sulfur organometallic compound.
• Non-limiting examples of reactive groups that the functionalizing agent can contain include, but are not limited to, vinyl, epoxy, glycidoxy and (meth) acryloxy.
• suitable materials can include, but are not limited to, chemicals such as natural or synthetic fats and oils and the non-sulfur organometallic compounds represented by chemical formulae II, III, IV, V and mixtures of such hydrophobizing agents.
• the initial step of contacting the acidic aqueous suspension of precipitated silica with a combination of bis (alkoxysilylalkyl)polysulfide and non-sulfur organometallic compound, such as a non-sulfur organosilicon compound, can further include adding a water miscible solvent in amounts sufficient to facilitate their reaction with the precipitated silica.
• the solvent can act as a phase transfer agent speeding- up the interaction of the combination of hydrophobic sulfur and non-sulfur organometallic compounds with the hydrophilic inorganic oxide.
• the amount of the water- miscible organic solvent can comprise at least 5 wt .
• wt % of the aqueous suspension can vary between any combination of these values, inclusive of the recited values.
• suitable water-miscible solvents can include but are not limited to alcohols such as ethanol, isopropanol and tetrahydrofuran.
• isopropanol can be used as the water-miscible organic solvent.
• a surfactant can be used in the initial step, either in combination with the water-miscible organic solvent or in place of the water-miscible organic solvent, in an amount sufficient to facilitate the chemical modification of the inorganic oxide by the bis (alkoxysilylalkyl)polysulfide and the non-sulfur compound.
• the surfactant can be selected from nonionic, anionic, cationic, amphoteric or a mixture of such surfactants.
• the surfactant can be selected such that it does not have an adverse effect on the performance of the resulting chemically modified inorganic oxide for its intended use.
• the surfactant when used, can be present in an amount of from 0.05 to 10 wt. % of the aqueous suspension, or from 0.1 to 5 wt. %, or from 0.1 to 3 wt . %, or the wt. % can vary between any combination of these values, inclusive of the recited values.
• Non-limiting examples of suitable surfactants can include but are not limited to alkylphenolpolyglycol ethers, e.g., p-octylphenolpolyethyleneglycol (20 units) ether, p-nonylphenolpolyethyleneglycol (20 units) ether, alkylpolyethyleneglycol ethers, e.g., dodecylpolyethyleneglycol (20 units) ether, polyglycols, e.g., polyethyleneglycol 2000, alkyltrimethylammonium salts, e.g., cetyltrimethylammonium chloride (or bromide), dialkyldimethylammonium salts, e.g., dilauryldimethylammonium chloride, alkylbenzyltrimethylammonium salts, alkylbenzenesulfonates, e.g., sodium p-dodecylbenzenesulfonate, sodium p-
• the surfactant can include a polysiloxane polymer or copolymer having an allyl end blocked polyethylene oxide.
• the bis (alkoxysilylalkyl) -polysulfides used to produce the modified fillers of the present invention can include those described in U.S. Patent Nos. 3,873,489 and 5,580,919, which relevant disclosure is incorporated herein by reference, and can be represented by the following formula VI :
• alk can be a divalent hydrocarbon radical having from 1 to 18, or 1 to 6, or 2 to 3 , carbon atoms; n' can be a whole number of 2 to 12, or 2 to 6, or 3 to 4; and Z can be:
• R can be an alkyl group having from 1 to 4 carbon atoms or phenyl
• R' can be an alkoxy group having from 1 to 8, or from 1 to 4, or from 1 to 2, carbon atoms, a cycloalkoxy group with from 5 to 8 carbon atoms, or a straight or branched chain alkylmercapto group with from 1 to 8 carbon atoms.
• the R and R' groups can be the same or different.
• the divalent alk group can be straight or branched chain, a saturated or unsaturated aliphatic hydrocarbon group or a cyclic hydrocarbon group.
• a high purity organosilane disulfide as disclosed in U.S. Patent Nos .
• Non-limiting examples of suitable bis (alkoxysilylalkyl) -polysulfides can include: the bis(2- trialkoxysilylethyl) -polysulfide in which the trialkoxy group can be trimethoxy, triethoxy, tri (methylethoxy) , tripropoxy, tributoxy, etc. up to trioctyloxy and the polysulfide can be the di-, tri-, tetra-, penta-, and hexasulfide.
• bis (3-trialkoxysilylpropyl) - bis (3-trialkoxysilylisobutyl) , - bis (4-trialkoxysilylbutyl) - , etc. up to bis (6-trialkoxysilyl- hexyl)polysulfide can also be used.
• - organosilanes including the bis (3-trimethoxy-, -triethoxy-, and - tripropoxysiIyI-propyl)polysulfide; such as, the di-, tri- and tetrasulfides, can be used.
• Non- limiting representative examples of such compounds are: 3,3'bis (trimethoxysilylpropyl) disulfide, 3,3' -bis (triethoxysilylpropyl) tetrasulfide,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,and 3,3'- bis (trioctoxysilylpropyl) tetrasulfide and mixtures thereof.
• the most preferred compound is 3, 3 ' -bis (triethoxy
• the non-sulfur organometallic compounds that can be used to produce the modified filler of the present invention can include at least one non- sulfur organometallic compound or a mixture of non-sulfur organometallic compounds selected from the group consisting of: organometallic compound(s) represented by formula II:
• organometallic compound(s) represented by formula III is represented by formula III:
• organometallic compound(s) represented by the formula IV:
• each R 1 can be a saturated or unsaturated monovalent hydrocarbon group or a substituted or non-substituted monovalent hydrocarbon group.
• R 1 can be alkyl groups such as methyl, ethyl, propyl, iso-propyl, iso-butyl, t-butyl, n-butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, and dodecyl; alkenyl groups such as vinyl,, allyl, and hexenyl; substituted alkyl groups such as chloromethyl, 3 ,3, 3-trifluoropropyl, and 6-chlorohexyl; cycloalkyl groups, such as cyclohexyl and cyclooctyl; aryl groups such as phenyl and naphthyl; and substituted aryl groups such as benzy
• the halogen when X is a halogen in formula II, the halogen can be chloro; when X is an alkoxy group, X can be methoxy, ethoxy, and propoxy; when X is an acyloxy group, X can be acetoxy. In another non-limiting embodiment, each X can be selected from chloro and methoxy.
• the viscosity of the afore-described organometallic compounds is not limiting and can range from that of a fluid to a gum. Generally, higher molecular weight organometallic compounds should be cleaved by the acidic conditions of the chemical modification step allowing them to react with the hydrophilic inorganic oxide.
• each R 2 , R 3 and R 4 can be the same as the hydrocarbon groups described for R 1 .
• the organometallic reactant is an organosilicon reactant
• the silicon is considered to be a metal.
• the non-sulfur organometallic compound(s) can be represented by formulae II, III, IV, V or a mixture of said organometallic compounds wherein each M can be silicon.
• the non- sulfur organometallic compound can be represented by formula II wherein R 1 can be C ⁇ -Cg alkyl, X can be chloro and a can be 2.
• Non-limiting examples of suitable organosilicon compounds can include, but are not limited to, compounds and mixtures of compounds selected from diethyldichlorosilane, allylmethyldichlorosilane, methylphenyldichlorosilane, phenylethyldiethoxysilane, 3,3,3- trifluoropropylmethyldichlorosilane, trimethylbutoxysilane, sym- diphenyltetramethyldisiloxane, trivinyltrimethyl- cyclotrisiloxane, octamethylcyclotetrasiloxane, hexaethyldisiloxane, pentylmethyldichlorosilane, divinyldipropoxysilane, vinyldimethylchlorosilane, vinylmethyldichlorosilane, vinyldimethylmethoxysilane, trimethylchlorosilane, trimethylmethoxysilane, trimethyl
• Non-limiting examples of suitable organotitanium compounds can include, but are not limited to, tetra(C ⁇ - C ] _g)alkoxy titanates, methyl triethoxy titanium (iv) , methyl titanium (iv) triisopropoxide, methyl titanium (iv) tributoxide, methyl titanium (iv) tri-t-butoxide, isopropyl titanium (iv) tributoxide, butyl titanium (iv) triethoxide, butyl titanium (iv) tributoxide, phenyl titanium (iv) triisopropoxide, phenyl titanium (iv) tributoxide, phenyl titanium (iv) triisobutoxide, [Ti(CH 2 Ph) 3 (NC 5 H 10 )] and [Ti (CH 2 SiMe 3 ) 2 (NEt 2 ) 2 ] • [0058]
• suitable organozirconium compounds can include, but
• the amount of mercaptoorganometallic compound and non- sulfur organometallic compound used in the afore-described chemical modification process can be that amount which is sufficient to produce a modified filler characterized by a carbon content of greater than 1 wt . %, a mercapto content of greater than 0.15 wt . %, a Silane Conversion Index of at least 0.3 and a Standard Reinforcement Index of at least 4.0.
• a coupling amount i.e., an amount sufficient to bind to the filler and enable the now modified filler to bind to the polymeric composition.
• the weight ratio of mercaptoorganosilane to non-sulfur organometallic compound can vary from at least 0.05:1, or from 0.05:1 to 10:1, or from 0.1:1 to 5:1, or from 0.2:1 to 2:1, or from 0.5:1 to 1:1 or the weight ratio can vary between any combination of these values, inclusive of the recited ranges.
• the individual organometallic reactants can be added together or sequentially in any order.
• the organometallic reactants can be present in an amount that provides an excess of organometallic units in relation to the hydroxyl groups available on the inorganic oxide particles for reaction.
• the upper limit of the amount of organometallic reactants added to the process is not critical. Excess mercaptoorganometallic compounds and non- sulfur organometallic compounds can be removed by filtration, distillation, washing with a solvent, or other known separation techniques.
• the mercaptoorganometallic reactant can be replaced by a combination of a mercaptoorganometallic and a different sulfur-containing organometallic compound in a weight ratio of mercaptoorganometallic compound to sulfur-containing organometallic compound of from at least greater than 1:1, or 1.01:1, or from 1.01:1 to 100:1, or from 5:1 to 50:1, or from 10:1 to 30:1 or the weight ratio can vary between any combination of these values, inclusive of the recited values.
• any sulfur-containing organometallic compound (other than the mercaptoorganometallic compound represented by formula I) , that can function as a coupling agent in the vulcanization of a filler containing rubber, can be suitable for use in the present invention.
• Non-limiting examples of suitable sulfur-containing organometallic compounds can include bis (alkoxysilylalkyl) - polysulfides as described previously herein.
• the amount of bis (alkoxylsilylalkyl)polysulfide and non-sulfur organometallic compound used in the afore-described chemical modification process is that amount which is sufficient to produce a modified filler characterized by a carbon content of greater than 1 wt. %, a sulfur content of greater than 0.1 wt. %, a Silane Conversion Index of at least 0.3 and a Standard Tensile Stress @ 300% elongation of at least 7.0.
• a coupling amount i.e., an amount sufficient to bind to the filler and enable the now modified filler to bind to the polymeric composition.
• the weight ratio of bis (alkoxylsilylalkyl)polysulfide to non-sulfur organometallic compound can vary from at least 0.05:1, or from 0.05:1 to 10:1, or from 0.1:1 to 5:1, or from 0.2:1 to 2:1, e.g., from 0.5:1 to 1:1 or the weight ratio can vary between any combination of these values, inclusive of the recited ranges.
• the individual organometallic reactants can be added together or sequentially in any order.
• the organometallic reactants can be present in an amount that provides an excess of organometallic units in relation to the hydroxyl groups available on the inorganic oxide particles for reaction.
• the upper limit of the amount of organometallic reactants added to the process is not critical . Excess bis (alkoxylsilylalkyl)polysulfide and non-sulfur organometallic compounds can be removed by filtration, distillation, washing with a solvent, or other known separation techniques.
• the bis (alkoxylsilylalkyl)polysulfide can be replaced by a combination of a bis (alkoxylsilylalkyl)polysulfide and a different sulfur-containing organometallic compound in a weight ratio of bis (alkoxylsilylalkyl)polysulfide to sulfur-containing organometallic compound of from at least greater than 1:1, or 1.01:1, or from 1.01:1 to 100:1, or from 5:1 to 50:1, or from 10:1 to 30:1 or the weight ratio can vary between any combination of these values, inclusive of the recited values.
• any sulfur-containing organometallic compound (other than the bis (alkoxylsilylalkyl)polysulfide represented by formula VI), that can function as a coupling agent in the vulcanization of a filler containing rubber, can be suitable for use in the present invention.
• Non-limiting examples of suitable sulfur-containing organometallic compounds can include mercaptoorganometallic reactants previously described herein.
• the pH of the aqueous suspension of modified inorganic oxide can be increased from the treatment pH of 2.5 or less to a pH from 3.0 to 10.0, or to 3 or higher, or 4 or higher, or 5 or higher, or 6 or higher, and 10 or less, or 9 or less, or 8 or less, or 7 or less.
• the pH of the aqueous suspension can vary between any combination of these levels, including the recited levels.
• the pH can be increased to neutralize the added or generated acidity and produce a final product (after drying) having a pH of from 5.0 to 10.0.
• the modified inorganic oxide can be recovered by filtering and drying or by contacting the aqueous suspension of modified inorganic oxide with a water-immiscible organic solvent at a solvent to inorganic oxide weight ratio greater than 1 to 1, or greater than 5 to 1.
• the modified inorganic oxide recovered in the solvent phase can be used without further treatment or dried.
• the present invention can include a composition comprising a slurry of the modified filler in a water-immiscible solvent. The concentration of the modified filler in the slurry- can range from 1 to 90 wt . % based on the total weight of the slurry.
• Non-limiting examples of suitable water-immiscible organic solvents can include low molecular weight siloxanes, such as but not limited to hexamethyldisiloxane, octamethylcyclotetrasiloxane, diphenyltetramethyldisiloxane and trimethylsiloxy end blocked polydimethylsiloxane fluids.
• siloxanes such as but not limited to hexamethyldisiloxane, octamethylcyclotetrasiloxane, diphenyltetramethyldisiloxane and trimethylsiloxy end blocked polydimethylsiloxane fluids.
• siloxane When a siloxane is employed as a solvent, it can act both as a solvent and as a reactant with the inorganic oxide.
• suitable water-immiscible organic solvents can include aromatic hydrocarbons, such as toluene and xylene; heptane and other aliphatic hydrocarbon solvents; cycloalkanes, such as cyclohexane,- ethers, such as diethylether and dibutylether; halohydrocarbon solvents, such as methylene chloride, chloroform, ethylene chloride, and chlorobenzene; and ketones, such as methylisobutylketone.
• aromatic hydrocarbons such as toluene and xylene
• heptane and other aliphatic hydrocarbon solvents such as cycloalkanes, such as cyclohexane,- ethers, such as diethylether and dibutylether
• halohydrocarbon solvents such as methylene chloride, chloroform, ethylene chloride, and chlorobenzene
• ketones such as methylisobutylketone
• the water-immiscible organic solvent which can be used to contact the aqueous suspension of hydrophobic particulate inorganic oxide may or may not contain one or more materials dissolved therein.
• Non- limiting examples of such materials can include, but are not limited to, one or more rubbers, oil, coupling agent, antioxidant, and accelerator.
• At least one benefit of the chemically modified filler of the present invention is that when compounded with a polymer, such as a rubber composition, alcohol evolution can be substantially suppressed.
• the reaction of the silica particle with the coupling agent of the present invention can yield the chemically modified filler of the present invention and a byproduct of alcohol.
• an ethoxy silane produces a byproduct of ethanol in reaction with silica.
• the process of the present invention can be performed in an aqueous environment under conditions that can result in essentially complete hydrolysis of the alkoxy group(s) .
• the alcohol by-product produced in the reaction between the coupling agent and silica can be retained in the aqueous phase.
• the chemically modified filler can be isolated from the aqueous phase (containing the alcohol) resulting in substantially no release of alcohol by the filler.
• the filler can release less than 4000 ppm alcohol.
• the filler can be compounded with a rubber composition in conventional amounts and the compounded rubber composition can result in substantially no release of alcohol.
• the compounded rubber composition can release less than 4000 ppm alcohol.
• the rubber composition includes from 10 to 150 parts of filler per 100 parts of rubber composition.
• a rubber composition compounded with the modified filler of the present invention and without the presence of bis (alkoxysilylalkyl)polysulfide can release at least 20% less alcohol than a rubber composition with conventional fillers and the presence of bis (alkoxysilylalkyl)polysulfide.
• the modified filler of the present invention (as a powder, granule, pellet, slurry, aqueous suspension or solvent suspension) can be combined with base material, i.e., material used in the product to be manufactured, to form a mixture referred to as a master batch.
• base material i.e., material used in the product to be manufactured
• the modified filler can be present in a higher concentration than in the final product. Aliquots of this mixture can be added to production-size quantities during mixing operations in order to aid in uniformly dispersing very small amounts of such additives to polymeric compositions, e.g., plastics, rubbers and coating compositions.
• the modified filler can be combined with emulsion and/or solution polymers, e.g., organic rubber comprising solution styrene/butadiene (SBR), polybutadiene rubber or a mixture thereof, to form a master batch.
• emulsion and/or solution polymers e.g., organic rubber comprising solution styrene/butadiene (SBR), polybutadiene rubber or a mixture thereof
• SBR solution styrene/butadiene
• a master batch comprising a combination of organic rubber, water-immiscible solvent, modified filler and, optionally, processing oil can be formed.
• Such a product can be supplied by a rubber producer to a tire manufacturer. At least one benefit to the tire manufacturer of using a master batch is that the modified filler can be uniformly dispersed in the rubber, which can substantially reduce or minimize the mixing time to produce the compounded rubber.
• the master batch can contain from 10 to 150 parts of modified silica per 100 parts of rubber (phr) , or from 20 to 130 phr, or from 30 to 100 phr, or from 50 to 80 phr.
• a polymeric article can have dispensed therein from 10 to 150 parts of modified filler per 100 parts of polymer, or from 20 to 130, or from 30 to 100, or from 50 to 80 parts of modified filler per 100 parts of polymer.
• the amount of modified filler can vary between any combination of these values, inclusive of the recited ranges.
• the polymer can be selected from thermoplastic resins, thermosetting resins and organic rubber.
• the polymer can be a curable organic rubber.
• Non-limiting examples of curable rubbers suitable for use in combination with the modified filler of the present invention are well-known to the skilled artisan in rubber chemistry and can include but are not limited to vulcanizable and sulfur-curable rubbers.
• the curable rubber can include those materials which are typically used for mechanical rubber goods.
• the modified filler of the present invention can be mixed with an uncured rubbery elastomer used to prepare the vulcanizable rubber composition by conventional means such as in a Banbury mixer or on a rubber mill at temperatures between about 100 0 F and 400 0 F (38°C-200°C) .
• a vulcanizable rubber composition can contain, based on 100 parts of vulcanizable rubber polymer, from 10 to 150 parts of modified filler, or from 20 to 130 phr, or from 30 to 100 phr, or from 50 to 80 phr.
• Non-limiting examples of other conventional rubber additives that can be present include but are not limited to the conventional sulfur or peroxide cure systems.
• the sulfur-cure system can include 0.5 to 5 parts sulfur, 2 to 5 parts zinc oxide and 0.5 to 5 parts accelerator.
• the peroxide-cure system can include 1 to 4 parts of peroxide such as dicumyl peroxide.
• a wide variety of other conventional rubber additives can also be used. Non-limiting examples of such additives can include but are not limited to other fillers, such as carbon black, oils, plasticizers, accelerators, antioxidants, heat stabilizers, light stabilizers, zone stabilizers, organic acids, such as for example stearic acid, benzoic acid, or salicylic acid, other activators, extenders and coloring pigments.
• the particular compounding recipe will vary with the particular vulcanizate prepared; but, such recipes are well-known to those skilled in the rubber compounding art .
• Another benefit of the chemically modified filler of the present invention can be its stability at elevated temperatures and/or the absence of curing of a rubber compounded therewith at temperatures up to at least 200 0 C when mixed for at least one half minute or up to 60 minutes.
• the compounding process can be performed batchwise or continuously.
• the rubber composition and at least a portion of the chemically modified composition can be continuously fed into an initial portion of a mixing path to produce a blend and the blend can be continuously fed into a second portion of the mixing path.
• a rubber composition compounded with the chemically- modified filler of the present invention can result in improved performance properties over those of a conventional sulfur- vulcanized coupling compounded with conventional fillers and bis (alkoxysilylalkyl) -polysulfide .
• the improved properties can include higher 300% modulus, higher ratio of 300% to 100% modulus, lower delta G', and lower tangent delta at 60 0 C.
• Another benefit of the present invention can be the ability to achieve desired cure kinetics and physical properties of rubber compounded with the chemically modified filler of the present invention and certain curative components.
• the desired cure kinetics can include a scorch time of greater than 2.5 minutes and a cure time of less than 30 minutes (TS2 and TC90, respectively, determined according to ASTM D5289-95) with the compounded product having a 300% modulus (determined according to ASTM D412-98a) of at least 6.5 MPa.
• Suitable curative components can include a wide variety of materials known to a skilled artisan, such as but not limited to accelerators and retardants.
• Non-limiting examples of suitable accelerator compositions can include: benzothiazoles such as :
• dithiocarbamates such as : bismuth dimethyldithiocarbamate, copper dimethyldithiocarbamate, cadmium diethyldithiocarbamate, lead diamyldithiocarbamate, lead dimethyldithiocarbamate, selenium diethyldithiocarbamate, selenium dimethyldithiocarbamate, tellurium diethyldithiocarbamate, zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, zinc diamyldithiocarbamate, zinc di-n-butyldithiocarbamate, zinc dimethylpentamethylenedithiocarbamate, piperidinium pentamethylene dithiocarbamate, 2- benzothiazyl-N,N-diethyldithiocarbamate, and dimethylam
• N,N' -dibutylthiourea dimethylethylthiourea, diphenylthiourea, and tetramethylthiourea
• xanthates such as: sodium isopropylxanthate, zinc isopropylxanthate, and zinc dibutylxanthate
• thiuramsulfides such as: tetramethylthiuram monosulfide, tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, tetrabenzylthiuram disulfide, dipentamethylenethiuram tetrasulfide, dimethyldiphenylthiuram disulfide, and dipentamethylenethiuram monosulfide; and amines such as: cyclohexylethylamine, dibutylamine, acetaldehyde-aniline condensation
• Non-limiting examples of suitable retardants can include at least one of: N- (cyclohexylthio) -phthalimide, phthalic anhydride, and aromatic sulfenamide.
• the vulcanizable rubber composition can be vulcanized or cured to a rubber vulcanizate in accordance with customary- procedures known in the rubber industry.
• industrial rubber vulcanizates (articles) which can be produced utilizing the modified filler of the present invention can include wire and cable jacketing, hoses, gaskets and seals, industrial and automotive drive-belts, engine mounts, V-belts, conveyor belts, roller coatings, tires and components of tires, such as vehicle tire treads, subtreads, tire carcasses, tire sidewalls, tire belt wedge, tire bead filler, and .tire wire skim coat, shoe sole materials, packing rings, damping elements and many others.
• Sundex 8125 aromatic hydrocarbon processing oil obtained commercially from Sun Company, Inc., Refining and Marketing Division.
• Wingstay ® 100 antiozonant a mixture of diaryl p- phenylenediamines, obtained commercially from The Goodyear Tire & Rubber Co.
• a 1.89 liter (L) Farrel Banbury mixer (Model "BR") was used for mixing the various ingredients. Immediately prior to adding the batch ingredients to the mixer, 800 grams (g) of CV-60 grade natural rubber was put through the mixer to clean it of any residue of previous runs and increase the temperature to about 93 0 C (200 0 F) . After removing the rubber, the mixer was cooled to about 65°C (150 0 F) before adding the ingredients to produce the rubber test sample.
• a rubber composition is prepared using the test filler, the following other enumerated ingredients and the procedure described hereinafter.
• Solflex 1216 solution styrene-butadiene rubber (SBR) obtained commercially from The Goodyear Tire & Rubber Co.
• Santoflex ® 13 antiozonant described as N- (1,3- dimethylbutyl) -N' -phenyl-p-phenylenediamine, obtained commercially from Flexsys.
• Okerin ® 7240 microcrystalline wax/paraffin wax blend obtained commercially from Astor Corporation.
• Rubber Makers (RM) sulfur 100% active, obtained commercially from Taber, Inc.
• the first pass was initiated by adding the rubber, viz., SBR and BR, to the mixer and mixing for 0.5 minute at 116 rpm.
• the rotor speed was maintained at 116 rpm and 57.5 phr of the treated filler sample was added.
• the ram was raised and the chute swept, i.e., the covering on the entry chute was raised and any material that was found in the chute was swept back into the mixer.
• the sample from Part A was added.
• the ram was raised and the chute swept.
• the contents in the mixer were mixed for an additional minute to achieve a maximum temperature in the range of from 145 to 15O 0 C (293 to 302 0 F) and to complete the first pass in the mixer.
• the rotor speed of the mixer may be increased or decreased after 4 minutes to achieve a temperature in the foregoing range within the specified mixing period.
• the temperature of the material was determined with a thermocouple to verify that it did not exceed the maximum temperature of 150 0 C.
• the removed material was weighed and sheeted in a Farrel 12 inch, two-roll rubber mill at 2.032 mm ⁇ 0.127 mm (0.080 inch ⁇ 0.005 inch) .
• the resulting milled stock was cut into strips in preparation for the second pass in the mixer.
• a Farrel 12 inch, two-roll rubber mill was heated to approximately 60 0 C (140 0 F) .
• the stock from the second pass of Part B was fed into the running mill with a nip setting of 2.032 mm ⁇ 0.127 mm (0.080 inch ⁇ 0.005 inch) .
• the resulting sheet was placed on a flat surface until the temperature of the sheet reached room temperature. Typically, the sheet cooled within about 30 minutes.
• the milled sheet was fed into the rubber mill with a nip setting of 3.81 mm ⁇ 0.51 mm (0.15 inch ⁇ 0.02 inch) .
• the rolling bank was adjusted, if necessary, to maintain a uniform thickness.
• the resulting material was subjected to 16 side cuts and then 8 end passes.
• the rubber mill nip was adjusted to produce a sheet thickness of 2.032 mm ⁇ 0.127 mm (0.080 inch + 0.005 inch) .
• the sheet stock collected off the mill was placed on a flat clean surface.
• a stencil Using a stencil, a rectangular sample 203.2 mm x 152.4 mm (8 inches x 6 inches) was cut from the sheet stock.
• the sample was conditioned, i.e., stored between clean polyethylene sheets and maintained for 15 to 18 hours at a temperature of 23° ⁇ 2 0 C, and a relative humidity of 50% + 5%.
• the sample was placed in a 203.2 mm x 152.4 mm x 2.286 mm (8 inches x 6 inches x 0.09 inch) standard frame machine steel compression mold having a polished surface.
• the sample was cured in a 61 centimeter x 61 centimeter (24 inches x 24 inches) 890 kilonewton (100 ton) 4-post electrically heated compression press, for T90, i.e., the time it takes for 90 percent of the cure to occur, in accordance with ASTM D-2084, plus 5 minutes at 150 0 C (302 0 F) under a pressure of 13.79 megapascals (2000 pounds per square inch) . Typically, curing was completed within about 10 minutes.
• the resulting cured rubber sheet was removed from the mold and maintained for 15 to 18 hours at a temperature of 23° ⁇ 2°C (73.4 ⁇ 3.6 0 F), and a relative humidity of 50% ⁇ 5% prior to testing in Part D.
• Testing was performed in accordance with ASTM D 412- 98a - Test Method A. Dumbbell test specimens were prepared using Die C. An Instron model 4204 with an automated contact extensiometer for measuring elongation was used. The cross-head speed was found to equal 508 mm/min. All calculations were done using the Series IX Automated Materials Testing software supplied by the manufacturer. The Reinforcement Index equals the Tensile Stress at 300% elongation (in MPa) divided by the Tensile Stress at 100% elongation (in MPa) . When the samples were prepared using the Standard Compounding Protocol, the results were reported as the Standard Reinforcement Index.
• Precipitated silica was produced by acidifying sodium silicate solution with sulfuric acid. The majority of the precipitate was formed at a pH above 8.5. Further precipitate was produced by continuing the acid addition until the solution pH reached a level from 3.3 to 4.0.
• the resulting filter cake was re-liquefied using a high shear agitator to form a solid in liquid suspension.
• the suspension was dried in a Niro spray drier (inlet temperature about 360 0 C and the outlet temperature about 110 0 C) .
• Listed in Table 1 are the surface areas of the precipitated silica used to prepare the modified silica of the Examples and Comparative Examples.
• the stirred mixture in the vessel containing the hydrophobic precipitated silica was then washed with about 30 kg of water. Enough additional toluene (typically 6.5 to 8.0 kg) was added to the stirred mixture to effect separation of the hydrophobic precipitated silica from the aqueous phase without forming an emulsion. The aqueous phase was drained. The stirred mixture containing the hydrophobic precipitated silica was then washed two more times with about 30 kg of water per wash. The aqueous phase was drained from the vessel after each wash and before addition of the subsequent wash.
• % NaOH was added to adjust the pH to about 7.0; enough toluene (about 7.1 kg) was added to effect separation of the hydrophobic silica from the aqueous phase without forming an emulsion.
• the recovered product was not subjected to water washing but, after draining the aqueous phase, about 2.2 kg of toluene was added to the product to make a flowable solid in liquid suspension.
• the treated silica sample was dried until a sample showed ⁇ 1.5 wt . % loss when exposed to 160 0 C for 10 minutes.
• Example 8 The procedure of Example 8 was followed except that 86.5 g of 3-mercaptopropyltrimethoxysilane (MPTMS) was used.
• MPTMS 3-mercaptopropyltrimethoxysilane
• the approximate wt. %s of MPTMS and DMDCS per silica on a dry basis and the weight ratio of MPTMS/DMDCS for the modified silica sample of Example 9 are listed in Table 2.
• silane DDCS & MPTMS
• acid sufficient to result in a pH of about 0.3
• the acid used was concentrated, i.e., about 96 wt. %, sulfuric acid in all of the examples except Example 13 which used concentrated hydrochloric acid.
• the resulting mixture was left quiescent for at least 15 minutes. Water was added, agitation applied and the pH was adjusted to 3.5 with 50 wt. % aqueous NaOH.
• the resulting aqueous suspension of hydrophobic silica was filtered and washed with water until the rinse water demonstrated a conductivity level of from about 300 to 800 micromhos.
• the hydrophobic silica was dried until a sample showed less than 2.5 wt . % loss when exposed to 106 0 C for 10 minutes.
• the approximate amounts of the silanes added to the slurry are reported in Table 2 on a percentage weight based on dry silica along with the weight ratios of MPTMS/DMDCS.
• a 1-2 mg sample in a sealed tin capsule was burned in an oxygen enriched atmosphere at 1040°C with a Helium carrier, quantitatively- combusted over Cr 2 O 3 , then the combustion gases were passed over Cu at 650 0 C, to eliminate the excess oxygen and reduce the oxides of nitrogen to nitrogen.
• the gases were then passed through a chromatographic column, separated and eluted as N 2 , CO 2 , and H 2 O.
• the eluted gases were measured by a thermal conductivity detector.
• the instrument was calibrated by combustion of standard compounds. Results are listed in Table 3.
• the percent mercapto (SH) listed in Table 3 was determined by accurately weighing 2-3 grams of the treated silica to the nearest 0.001 g in an Erlenmeyer flask, adding 75 ml of isopropyl alcohol, flushing with nitrogen, sealing with a wet stopper and magnetically stirring for 30 minutes. The stirred solution was titrated quickly with standard 0.01N Iodine solution, commercially available from LabChem Inc., to a slight yellow endpoint . A blank titration was also done by following the same procedure except without adding the treated silica. If blocked mercaptosilane was used to modify the filler, it will be necessary to deblock the blocked mercaptosilane before titrating. The following equation was used to obtain the final value:
• Vl is the volume of iodine solution used with the sample
• V2 is the volume of iodine solution used in the blank
• N is the normality of the iodine solution
• W is the weight of the silica in grams.
• Silane Conversion Index reported as SCI in Table 3 was determined by solid state 29 Si NMR. This data was collected at ambient temperature on a Bruker AM-300 NMR with a narrow bore magnet and a Doty 7 mm standard speed MAS probe. Samples were packed into 7 mm o.d. zirconia rotors and sealed with short KeI-F caps. The rotors were spun at the Magic Angle with a speed of about 5.0 kHz.
• Cross Polarization (CP/MAS) data was collected using a 90° 1 H pulse, 5600 - 8400 scans per spectrum, a 5 msecond contact time, high power proton decoupling during data acquisition, and a 3 second relaxation delay.
• pH determinations were made on the treated filler of the Examples and Comparative Examples by the following procedure: add 5.0 g of silica (in powder form) to a 150 mL beaker containing a magnetic stir bar; add 50 mL of isopropanol and 50 mL of deionized water; and stir vigorously without splashing until the silica is suspended. Place a calibrated pH electrode in the vigorously stirring solution and record the pH reading after one minute (+_ 5 sec) . The results are listed in Table 3.
• the Soxhlet Extractable percent carbon of the treated silica of Examples 1, 2 and 7 was determined by adding approximately 5 grams of each material to 43 mm x 123 mm (internal diameter x external length) cellulose extraction thimbles which was placed into an appropriately sized Soxhlet extraction tube which was fitted with a condenser. This Soxhlet extractor and condenser system was attached to a round bottom flask containing 700 mL of toluene. The flask was heated to the reflux temperature of the toluene.
• CiptaneV 1 3.0 0.0 3 0
• ND* indicates that the test was not done.
• SCI** represents the Silane Conversion Index.
• SRI*** represents the Standard Reinforcement Index.
• a 1.89 liter (L) Farrel B Banbury mixer (Model "BR") was used for mixing the various ingredients .
• 800 grams (g) of CV-60 grade natural rubber was put through the mixer to clean it of any residue of previous runs and increase the temperature to about 93 0 C (200 0 F) .
• the mixer was cooled to about 65 0 C (150°F) before adding the ingredients to produce the rubber test samples.
• the first pass was initiated by adding the rubber, viz., sSBR and BR, to the mixer and mixing for 0.5 minute at 116 rpm.
• the rotor speed was maintained at 116 rpm and the appropriate amount of the specified filler indicated in Table 7 was added.
• the ram was raised and the chute swept, i.e., the covering on the entry chute was raised and any material that was found in the chute was swept back into the mixer.
• the sample from Part A was added.
• the ram was raised and the chute swept.
• the contents in the mixer were mixed for the additional time (DUMP TIME) to the maximum temperature (DUMP TEMP) indicated in Table 7 to complete the first pass in the mixer.
• the rotor speed of the mixer was increased or decreased to achieve the maximum temperature (DUMP TEMP) within the specified mixing period (DUMP TIME) .
• the temperature of the material was determined with a thermocouple to verify that it did not exceed the maximum temperature (DUMP TEMP) indicated.
• the removed material was weighed and sheeted in a Farrel 12 inch two-roll rubber mill at 2.032 mm ⁇ 0.127 mm (0.080 inch ⁇ 0.005 inch) .
• the resulting milled stock was cut into strips in preparation for the second pass in the mixer.
• a minimum of one hour was allotted between the completion of the first pass in the mixer and the beginning of the second pass to allow the milled stock to cool. If needed, the aforedescribed cleaning and warming-up procedure using CV-60 grade natural rubber was completed prior to initiating the second pass.
• the temperature of the mixer was adjusted to approximately 49°C. (120 0 F. ) .
• the second pass was initiated by adding the strips of first pass stock to the mixer operating at 77 rpm and the preweighed combination of Santoflex ® 13 antiozonant and Okerin® 7240 microcrystalline wax/paraffin wax blend. After 0.5 minutes, the second addition of the combination of RM Sulfur, TBBS and DPG was added. After a further 1.5 minutes, the ram was raised and the chute swept. The second pass was completed by mixing the stock an additional 2.0 minutes while maintaining the temperature at or below 125°C. (257°F. ) .
• a Farrel 12 inch two-roll rubber mill was heated to approximately 60 0 C. (140 0 F.) .
• the stock from the second pass of Part B was fed into the running mill with a nip setting of 2.032 mm ⁇ 0.127 mm (0.080 inch ⁇ 0.005 inch) .
• the resulting sheet was placed on a flat surface until the temperature of the sheet reached room temperature. Typically, the sheet cooled within about 30 minutes.
• the milled sheet was fed into the rubber mill with a nip setting of 3.81 mm ⁇ 0.51 mm (0.15 inch + 0.02 inch) .
• the rolling bank was adjusted, if necessary, to maintain a uniform thickness.
• the resulting material was subjected to 16 side cuts and then 8 end passes.
• the rubber mill nip was adjusted to produce a sheet thickness of 2.032 mm ⁇ 0.127 mm (0.080 inch ⁇ 0.005 inch) .
• the sheet stock collected off the mill was placed on a flat clean surface. Using a stencil, a rectangular sample 203.2 mm x 152.4 mm (8 inches x 6 inches) was cut from the sheet stock.
• the sample (compound A) was conditioned, i.e., stored between clean polyethylene sheets and maintained for 15 to 18 hours at a temperature of 23° ⁇ 2° C, and a relative humidity of 50% + 5%. Some of this compound was used for alcohol emissions testing as described below.
• the sample was placed in a 203.2 mm x 152.4 mm x 2.286 mm (8 inch x 6 inch x 0.09 inch) standard frame machine steel compression mold having a polished surface.
• the sample was cured in a 61 centimeter x 61 centimeter (24 inch x 24 inch) 890 kilo newton (100 ton) 4-post electrically heated compression press, for T90, i.e., the time it takes for 90 percent of the cure to occur, in accordance with ASTM D-2084, plus 5 minutes at ⁇ 150 0 C(302°F) under a pressure of 13.79 megapascals (2000 pounds per square inch) . Typically, curing was completed within about 10 minutes.
• the resulting cured rubber sheet was removed from the mold and maintained for 15 to 18' hours at a temperature of 23° ⁇ 2°C. (73.4 ⁇ 3.6°F.), and a relative humidity of 50% ⁇ 5% prior to testing.
• These sheets (compound B) were used to produce the test specimens for alcohol emissions, modulus @ 300% and Ratio 300% / 100% Modulus determinations.
• Alcohol emissions were determined by analyzing the samples using headspace-GC in accordance with the conditions hereinafter described in Example 23.
• the before cure (BC) samples i.e. compound A
• the after cure (AC) samples i.e. compound B
• the sample size was approximately 35 mg.
• Each compound was analyzed in triplicate with samples being taken diagonally across the sample. To account for differences in sample weights between runs the peak area was divided by the sample weight. The relative concentrations are based on compound 16.3 BC since this had the largest amount present.
• the Modulus @ 300% and Ratio 300% / 100% Modulus was determined in accordance with ASTM D 412-98a - Test Method A.
• the dumbbell test specimens were prepared using Die C.
• An Instron model 4204 with an automated contact extensiometer for measuring elongation was used.
• the cross-head speed was found to equal 508 mm/min. All calculations were done using the Series IX Automated Materials Testing software supplied by the manufacturer.
• the Ratio 300%/100% Modulus equals the Tensile Stress at 300% elongation (in MPa) divided by the Tensile Stress at 100% elongation (in MPa) .
• the compounding ingredient X 50-S ® is a 1:1 blend of the bifunctional, sulfur-containing organosilane Si 69 ⁇ (Bis- (triethoxysilyethoxy tetrasulfide) ) and an N 330 type carbon black, obtained commercially from Degussa.
• the rubber compositions were prepared using the enumerated ingredients shown in Table 10 and the procedure described hereinafter.
• a CW. Brabender Mixer Type EPL2-5501 equipped with Banbury blades and with an oil heated 350-420 ml mixing chamber was used for mixing the various ingredients . The mixer was allowed to warm for approximately 30 minutes to between 70 and 80 0 C.
• the first pass was initiated by adding the rubber, viz., sSBR and BR, to the mixer and mixing for 0.5 minute at 85 rpm.
• the rotor speed was maintained at 85 rpm and the appropriate amount of the specified filler was added.
• the ram was raised and an additional amount of the specified filler and, for compound 17.2, 13.0 phr of X-50S was added.
• the sample from Part A.I or A.2 was added.
• the contents in the mixer were mixed for an additional 2.5 or 3.0 minutes to the maximum temperature indicated. During this additional mixing time the ram was periodically raised and swept to ensure that all material was incorporated into the mix.
• the rotor speed of the mixer was increased or decreased to achieve the maximum temperature within the specified mixing period.
• the temperature of the material was determined with a thermocouple to verify that it did not exceed the maximum temperature indicated.
• the removed material was weighed and sheeted in a Farrel 12 inch two-roll rubber mill at 2.032 mm + 0.127 mm (0.080 inch ⁇ 0.005 inch) .
• the resulting milled stock was allowed to cool to room temperature.
• the cure profile was determined using a MDR 2000 (Moving Die Rheometer) following the Standard Test Method for Rubber Property - Vulcanization Using Rotorless Cure Meters, ASTM Designation: D 5289-95. Individual samples were tested at temperatures from 120 0 C to 190 0 C at 10 0 C increments.
• the cure profile for the inventive compound (17.1) is shown graphically in figure 1 and the cure profile for the comparative compound (17.2) is shown in figure 2.
• Part C of the Standard Compounding Protocol was performed on Compounds 1-8. The sheets were used to produce the test specimens for the Modulus @ 200%, Modulus @ 300%, Ratio 200%/l00% Modulus, and Ratio 300%/100% Modulus determinations.
• Rebound buttons were produced by taking the material . • subjected to the 16 side cuts and then 8 end passes and sheeting off at 3.81 mm + 0.13 mm (0.150 inch +/- 0.005 inch) . The resulting sheet was removed from the mill and folded in half making a sheet stock thickness of 7.62 mm _+ 0.13 mm (0.300 inch +/- 0.005 inch) . Using a one inch punch, three samples were punched out of this sheet stock. The samples were than stacked on top of one another. The total weight of the sample was 12 grams +/- 1 gram. The samples were cured in a 1 1/8 inch round by Vi inch .thick cavity with a flat plate on the top and bottom.
• the samples were cured in a 61 centimeter x 61 centimeter (24 inch x 24 inch) 890 kilonewton (100 ton) 4-post electrically heated compression press, for T90, i.e., the time it takes for 90 percent of the cure to occur, in accordance with ASTM D-2084, plus 10 minutes at 150 0 C (302 0 F) under a pressure of 13.70 megapascals (2000 pounds per square inch) . Typically, curing was completed within about 15 minutes.
• the resulting cured rubber sheet was removed from the mold and maintained for 15 to 18 hours at a temperature of 23° + 2°C (73.4 +_ 3.6°F), and a relative humidity of 50% + 5% prior to testing in Part D.
• the Mooney Scorch (T5) was determined using a Mooney Viscometer Model MV 2000 equipped with a small rotor following the Standard Test Method for Rubber-Pre-Vulcanization Characteristics, ASTM Designation: D 1646-98a.
• Mooney Viscosity ML4100°C was determined using a Mooney Viscometer Model MV 2000 equipped with a large rotor following the Standard Test Method for Rubber-Pre-Vulcanization Characteristics, ASTM Designation: D 1646-98a.
• the Scorch Time was determined using a MDR 2000 (Moving Die Rheometer) following the Standard Test Method for Rubber Property-Vulcanization Using Rotorless Cure Meters, ASTM Designation: D 5289-95.
• the Modulus @ 200%, Modulus @ 300%, Ratio 200%/100% Modulus, and Ratio 300%/l00% Modulus was determined in accordance with ASTM D 412-98a - Test Method A.
• the dumbbell test specimens were prepared using Die C.
• An Instron Model 4204 with an automated contact extensiometer for measuring elongation was used.
• the cross-head speed was found to equal 508 mm/min. All calculations were done using the Series IX Automated Materials Testing software supplied by the manufacturer.
• the Ratio 200%/l00% Modulus equals the Tensile Stress at 200% elongation (in MPa) divided by the Tensile Stress at 100% elongation (in MPa) .
• the Ratio 300%/100% Modulus equals the Tensile Stress at 300% elongation (in MPa) divided by the Tensile Stress at 100% elongation (in MPa) .
• the elastic or storage modulus at 1% strain was determined using a Rheometrics Dynamic Analyzer 2 following ISO Method 2856 Elastomers - General Requirements for Dynamic Testing.
• the cylindrical specimen 11 mm in diameter and weighing 0.86 j f O.Olg, is compression molded and cured between two 25 mm appropriately primed parallel sample plates at 150°C for T90 + 10 minutes.
• the elastic or storage modulus (G') is measured at strains ranging from 0.1% to 20% at 1 HZ and 30 0 C.
• the elastic or storage modulus at 1% strain (G', 1% Strain) is calculated from a polynomial equation which was fit to the data (r 2 >0.99) .
• Rebound @ 23°C and Rebound @ 100 0 C were determined using a Zwick 5109 Rebound Resilience Tester following the Standard Test Method for Rubber Property - Resilience Using a Rebound Pendulum, ASTM Designation: D 1054-91.
• the Tangent delta @ 60 0 C and Tangent delta at 0 0 C were determined using a Rheometrics Dynamic Analyzer 2 following ISO Method 2856 Elastomers - General Requirements for Dynamic Testing.
• the cylindrical specimen, 11 mm in diameter and weighing 0.86 + 0.0Ig, is compression molded and cured between two 25 mm appropriately primed parallel sample plates at 150 0 C for T90 + 10 minutes.
• the Tangent delta is measured at temperatures ranging from - 45°C to 75°C at 1 HZ and 2% strain.
• the Tangent delta @ 60 0 C and Tangent delta at 0 0 C is calculated from a polynomial equation which was fit to the data (r 2 >0.99) .
• the data of Table 12 demonstrates the effect of dump time at constant dump temperature on compound performance properties.
• the results show that increasing the dump time from 4 minutes to 7 minutes increases scorch time, ratio 300%/100% modulus and rebound at 100 0 C; while decreasing G' at 1% strain and tangent delta at 60 0 C.'
• These results indicate that compounds reinforced with the filler of the present invention and produced with longer dump (mix) times at constant dump temperature can have improved scorch safety during curing and that the cured compounds could provide improved treadwear and lower rolling resistance in a tire.
• the data of Table 13 demonstrates the effect of dump temperature at constant dump time on compound performance.
• [00163] Filler A was compounded using the ingredients and first pass procedure described in the Standard Compounding Protocol to produce part A shown in Table 15. The following procedure and ingredients enumerated in Table 15 were used for the second pass.
• the second addition of the combination of RM Sulfur and accelerators was added.
• the second pass was completed by mixing the stock an additional 2.0 minutes while maintaining the temperature at or below 125°C. (257°F.) .
• the temperature of the material was determined with a thermocouple to verify that it did not exceed 125°C. Cured sheets were produced following part C of the Standard Compounding Protocol .
• Altax 2-2 ' -dithiobisbenzothiazole obtained commercially from R.T. Vanderbilt Co., Inc.
• Antiozonant 2 0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2 0 2.0 2.0 2 .0
• TBBS 1 0 1.0 1.0 1.0 1.0 2.0 2.0 2 0 2.0 2.0 3 .0 2.0
• Retarder AK a modified phthalic anhydride obtained commercially from Akrochem Corporation
• a chemically modified filler of the present invention was prepared following the procedure described in Example 11.
• the % MPTMS/SiO2 was 5.50 and the % DMDCS/SiO2 was 19.6.
• Filler A had the following properties: N2 1 pt.
• Comparative filler B was a conventional non-treated precipitated silica.
• Comparative filler C was prepared by physically blending a conventional non-treated silica powder with mercaptopropyltrimethoxysilane (MPTMS) .
• the % MPTMS/SiO2 was 3.0.
• Comparative filler D was prepared by physically blending a conventional non-treated silica powder with mercaptopropyltriethoxysilane (MPTES) .
• the % MPTES/SiO2 was 6.0.
• Comparative filler E was prepared by physically blending a conventional non-treated silica powder with 3,3 ' -bis (triethoxysilylpropyl) tetrasulfide (TESPT) .
• TESPT 3,3 ' -bis (triethoxysilylpropyl) tetrasulfide
• % TESPT/SiO2 was 8.0. Essentially equal portions of each filler were analyzed for alcohol emissions using headspace-GC analysis under the following conditions:
• Headspace Oven 150 0 C
• TESPT Si-69 reinforcing agent
• TESPT Si-69 reinforcing agent
• DMDCS dimethyldichlorosilane
• the mixture was heated to about 68 0 C and held at this temperature for about 10 minutes. While cooling, enough toluene (typically 15 kg) was added to the stirred mixture to effect separation of the hydrophobic precipitated silica from the aqueous phase without forming an emulsion. The aqueous phase was drained from the vessel. The stirred mixture in the vessel containing the hydrophobic precipitated silica was then washed twice with about 30 kg for Example 24 and about 40 kg for Example 25 of water containing about 400 grams for Example 24 and 500 grams for Example 25 of sodium bicarbonate. The aqueous phase was drained.
• Example 24 After washing was completed, enough additional toluene (about 13.9 kg for Example 24 and 23.7 kg for Example 25 was added to the stirred mixture to make a flowable solid- in-liquid suspension that could be easily discharged from the vessel.
• the resulting suspension was dried in a rotocone drier under vacuum (minimum 23 inches of mercury) at a minimum of 140 0 C. Drying was continued until the samples showed a wt .% loss of less than 4.5 % when exposed to 160 0 C for 10 minutes .
• DMDCS dimethyldichlorosilane
• the ASTM procedure was modified as follows: a 30% nitrogen-in-helium gas mixture was used; a flow of approximately 40 mL/min was maintained; samples were dried in the analysis cells under a flow of nitrogen at 180 ⁇ 5 0 C for one hour; and the adsorbed nitrogen on the sample was desorbed by removing the dewar of liquid nitrogen and allowing the sample to warm to room temperature with no external heat source. Results for the untreated test silica samples are listed in Table 26 and for the treated test silica samples are listed in Table 29.
• the percent carbon was determined by CHN analysis using a Carlo Erba model 1106 elemental analyzer.
• a 1 - 2 mg sample in a sealed tin capsule was burned in an oxygen enriched atmosphere at 1040 0 C with a Helium carrier, quantitatively combusted over Cr 2 O 3 , then the combustion gases were passed over Cu at 650 0 C, to eliminate the excess oxygen and reduce the oxides of nitrogen to nitrogen.
• the gases were then passed through a chromatographic column, separated and eluted as N 2 , CO 2 , and H 2 O.
• the eluted gases were measured by a thermal conductivity detector.
• the instrument was calibrated by combustion of standard compounds. Results are listed in Table 29.
• the percent sulfur was determined by x-ray- fluorescence spectrometry (XRF) , using a Rigaku RIX 2000 wavelength-dispersive spectrometer. Samples were briquetted into aluminum support cups at 344.75 megapascals (25 tons/in 2 ) pressure after mixing with SpectroBlend ® binder (Chemplex Industries, Tuckahoe, NY) in a 1:1 weight ratio. NIST- and NBS- traceable secondary standards (PPG production silicas, or equivalent) were used for the empirical XRF calibration. Detection was via a gas-proportional flow counter using a germanium crystal monochromator. Results are listed in Table 29.
• Silane Conversion Index reported as SCI in Table 29 was determined by solid state 29 Si NMR. This data was collected at ambient temperature on a Bruker AM-300 NMR with a narrow bore magnet and a Doty 7 mm standard speed MAS probe. Samples were packed into 7 mm o.d. zirconia rotors and sealed with short KeI-F caps. The rotors were spun at the Magic Angle with a speed of about 5.0 kHz.
• Cross Polarization (CP/MAS) data was collected using a 90° 1 H pulse, 5600 - 8400 scans per spectrum, a 5 msecond contact time, high power proton decoupling during data acquisition, and a 3 second relaxation delay.
• pH determinations were made on the treated silicas of the Examples and Comparative Examples by the following procedure: add 5.0 g of silica (in powder form) to a 150 mL beaker containing a magnetic stir bar,- add 50 mL of isopropanol and 50 mL of deionized water; and stir vigorously without splashing until the silica is suspended. Place a calibrated pH electrode in the vigorously stirring solution and record the pH reading after one minute ⁇ +_ 5 sec) . The results are listed in Table 29.
• the Soxhlet Extractable percent carbon of the treated silica of Example 1 was determined by adding 5.44 grams of the material to a 43 mm x 123 mm (internal diameter x external length) cellulose extraction thimble which was placed into an appropriately sized Soxhlet extraction tube which was fitted with a condenser.
• This Soxhlet extractor and condenser system was attached to a round bottom flask containing 700 mL of toluene. The flask heated to the reflux temperature of the toluene. After refluxing for 25 hours, the used toluene was replaced with unused toluene and refluxing was continued for 22.5 hours.
• the resulting extracted treated silica was recovered and dried until a sample showed a 1.0 weight percent loss when exposed to 160 0 C for 10 minutes.
• the percent carbon of the extracted sample was determined using the procedure described herein.
• the Soxhlet extractable percent carbon was determined using the following equation:
• Alcohol emissions was determined using headspace-GC analysis under the following conditions:
• Headspace Oven 150 0 C
• amphoteric surfactant reported to be based on cocamidopropyl aminobetaine, available from BASF.
• a nonionic surfactant reported to be based on an alkylchloride end-capped ethylene oxide, available from BASF.
• a nonionic surfactant reported to be based on glycol ether, available from BASF.
• a nonionic surfactant reported to be based on an polyoxethylene lauryl ether, available from Aldrich Chemical Co.
• ND* indicates that the test was not done.
• SCI** represents the Silane Conversion Index.
• Comparative Example 32 had a Carbon weight percent lower than the required amount and demonstrated an STS @ 300% of 3.6. Both Comparative Examples 33 and 34 had carbon and sulfur levels within the necessary ranges, but both had an STS @ 300% of less than 7.0. Comparative Example 34 also had a SCI value less than the required value.

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