A rubber composition containing a fluoroglucinol resin for use in a tire tread of a large vehicle

Abstract

A silane-based additive, a rubber formulation containing the additive, and a tire having a tread portion made of the additive are provided, along with a method of forming those products. An uncured rubber formulation according to a preferred embodiment of the present invention comprises (1) a rubbery primary polymer or polymer blend, such as natural rubber and / or synthetic rubber; (2) a reinforcing silica filler; (3) a methylene donor compound; (4) a silane containing one or more moieties of the aforementioned network-forming polymer; and (5) a phloroglucinol resin. Networks that can be generated in situ are particularly preferred. The cured rubber formulation preferably comprises silica bonded with an interpenetrating polymer network that reinforces the load-bearing paths and is not directly bonded to the rubber chains via sulfide bonds within the rubber matrix.

Description

[Technical Field]

[0001] This invention generally relates to rubber compounds for use in tires of heavy vehicles such as large trucks and buses. More specifically, the invention relates to an environmentally friendly and fuel-efficient rubber compound for use in the treads of truck and bus tires, which, unexpectedly, does not contain resorcinol and provides superior rolling resistance characteristics compared to such rubber compounds. [Background technology]

[0002] In the United States, there is an unmet need for further reductions in tire fuel efficiency due to Corporate Average Fuel Economy (CAFE) standards, Greenhouse Gas (GHG) protocols, and other laws issued by the National Highway Transportation Safety Administration (NHTSA) and the Environmental Protection Agency (EPA), as well as regulations issued by Transport Canada and the Canadian Health Ministry, and the European Union Tyre Label in Europe. One way to determine fuel efficiency is to examine the rolling resistance of the rubber composition, which can be determined by various mechanical properties of the rubber composition. Simply put, the lower the rolling resistance of the rubber composition, the better the tire's fuel efficiency.

[0003] It is generally known in the art that various properties, such as wet traction and rolling resistance, can be improved by adding organosilane coupling agents containing silica or sulfur to tire tread rubber compositions. For example, Japanese Patent No. 50-88150 shows that a tire tread for winter tires treated with a silane compound containing silica and sulfur atoms added to the rubber compound has improved slip resistance. Similarly, European Patent No. 0299074 proposed the use of a functionalized alkoxysilane in a rubber composition containing silica as a reinforcing filler. Similarly, U.S. Patent No. 5,227,425, the disclosure of which is incorporated herein by reference in whole, discloses a tire tread composition in which the rubber component is a copolymer of conjugated dienes and vinyl-containing aromatic compounds prepared in solution, and a carbon black filler is partially or completely replaced with a silica and silane coupling agent added separately from the polymer during mixing.

[0004] However, these rubber compounds cannot withstand the loads required for large vehicles such as commercial medium-duty trucks weighing more than 13,000 pounds or heavy-duty trucks weighing more than 26,000 pounds. These rubber compounds are more suitable for smaller tires, such as those used in passenger cars and light trucks.

[0005] Attempts have been made to address the problem of providing fuel-efficient treads for truck or bus tires by providing high-load-resistant tread compositions with the stress-strain properties of silica-reinforced natural rubber. One such attempt is provided in U.S. Patent Application Publication 2020 / 0140661, now U.S. Patent No. 11,267,955, which discloses and claims a rubber compound containing natural rubber, a special silane coupling agent such as silane functionalized with hexamethoxymethylmelamine (HMMM), a reinforcing filler such as silica, and a secondary network based on resorcinol or resorcinol-formaldehyde resin. It is noteworthy that this patent refers to phloroglucinol as a compound containing potentially active hydrogen. However, as will be described below, phloroglucinol is not phloroglucinol resin. Furthermore, it should be noted that this patent claims a silane functionalized with a reinforcing filler and reactive hexamethoxymethylmelamine. This is considered the novelty of the patent, and the claims do not specify the use of hexamethoxymethylmelamine (HMMM) separately from the silane.

[0006] On the other hand, resorcinol-formaldehyde resins, also known as RF resins or resorcinol-based resins, which are formed as reaction products of resorcinol and formaldehyde, are widely used in a variety of applications, including rubber compounding. In rubber compound formulations, solid RF resins have long been used to enhance rubber properties such as the adhesion between rubber and reinforcing materials, as well as the mechanical properties of articles such as tires, belts, and hoses.

[0007] A problem associated with these resins is that resorcinol resins generally contain 10-20% unreacted or free resorcinol. The amount of free resorcinol can be a critical factor when balancing important properties and when its presence can be problematic. For example, free resorcinol can volatilize during rubber mixing. Such volatilization is often referred to as fume emission and therefore creates additional problems in the rubber mixing process. Furthermore, the presence of free resorcinol contributes to the hygroscopicity of resorcinol resins, which in turn leads to storage and handling problems.

[0008] Furthermore, formaldehyde has been used for many years to create resorcinol-formaldehyde resins. Given its widespread use, toxicity, and volatility, formaldehyde presents potential health and environmental problems. In 2011, the U.S. National Toxicology Program listed formaldehyde as a known human carcinogen. Therefore, rubber compositions containing resorcinol or resorcinol-formaldehyde resin compounds are unacceptable to new tire manufacturers today.

[0009] International Publication No. 2021 / 141934 provides the use of phloroglucinol resin as a substitute for resorcinol or resorcinol-formaldehyde resin, but only when no silane additive is used. That is, as with many of the other patents cited above, these resins are only suitable for rubber compositions for use in tires of light vehicles, because no silane additive was used in those patents or tires. [Overview of the project] [Problems that the invention aims to solve]

[0010] Therefore, there is a need to develop reinforced natural rubber with stress-strain properties for use in tires for large vehicles (e.g., medium to large trucks and buses), and high-load-resistant rubber compounds with fuel-efficient silica-based treads. [Means for solving the problem]

[0011] To establish highly fuel-efficient tires for heavy trucks and buses that do not contain resorcinol or formaldehyde, a rubber compound formulation was created consisting of natural rubber, silica, a special silane coupling agent, hexamethoxymethylmelamine (HMMM) (separate from the silane coupling agent), and phloroglucinol resin. Surprisingly and unexpectedly, these rubber formulations showed much better fuel efficiency and durability compared to compounds containing resorcinol. This invention provides a much better natural rubber-silica tread compound for trucks and buses, without resorcinol or formaldehyde.

[0012] At least one aspect of the present invention can be seen in a rubber composition comprising (a) a rubbery polymer or a blend of polymers; (b) at least one organosilane coupling agent; (c) at least one reinforcing filler reactive with at least one organosilane coupling agent; (d) at least one methylene donor compound; (e) at least one phloroglucinol resin; and (f) at least one sulfur-donating compound. In various embodiments, the rubber composition comprises the above components, wherein the rubbery component (a) is in the range of about 25 to about 95 weight percent based on the total weight of the rubber composition; the organosilane coupling agent (b) is in the range of 0.05 to 30 parts of organosilane coupling agent (b) per 100 parts of the rubbery polymer; the reinforcing filler (c) reactive with organosilane coupling agent (b) is in the range of 1 to 150 parts of reinforcing filler per 100 parts of the rubbery polymer; the methylene donor compound (d) is in the range of 0.1 to 30 parts of methylene donor compound per 100 parts of the rubbery polymer; the phloroglucinol resin (e) is in the range of 0.1 to 10 parts of phloroglucinol resin per 100 parts of the rubbery polymer; and the sulfur-donating compound (f) is in the range of 0.1 to 5 parts of sulfur-donating compound per 100 parts of the rubbery compound.

[0013] In one or more embodiments, the rubbery polymer (a) is natural rubber (NR), synthetic polyisoprene (IR), polybutadiene (BR), various copolymers of butadiene, copolymers of isoprene, solution styrene-butadiene rubber (SSBR), emulsion styrene-butadiene rubber (ESBR), ethylene-propylene polymer (EPDM), acrylonitrile-butadiene rubber (NBR), and at least one alkoxysilyl group, tin-containing group, amino group, hydroxyl group, carboxylic acid group, polysiloxane group, epoxy group or phthalocyanine of The group may be selected from functionalized rubbers modified with a specific compound. In other, more specific embodiments, the rubbery polymer includes natural rubber or a mixture of natural rubber and butadiene rubber.

[0014] In these and other embodiments, the reinforcing filler (b) may be selected from a sheet-like structure comprising fibers, fine particles, or a metalloid oxide or metal oxide having surface hydroxyl groups. In the same or other embodiments, the reinforcing filler (b) comprises precipitated silica.

[0015] In these and other embodiments, the methylene donor compound (d) may be selected from the group consisting of polyisocyanates, polyisocyanurates, epoxy resins, amino resins, and polyurethanes. In these and other embodiments, the amino resin is included, and includes 1,1,3,3-tetra-methoxymethylurea, 1,3,3-tris-methoxymethylurea, 1,3-bis-methoxymethylurea, 1,1-bis-methoxymethylurea, 1,1,3,3-tetra-ethoxymethylurea, 1,3,3-tris-ethoxymethylurea, 1,3-bis-ethoxymethylurea, 1,1-bis-ethoxymethylurea, 1,1,3,3-tetra-propoxymethylurea, 1,3,3-tris-propoxymethylurea, 1,3-bis-propoxymethylurea, 1,1-bis-propoxymethylurea, 1,1,3,3-tetra-butoxymethylurea, 1,1,3,3-tetra-phenoxymethylurea, N-(1,3,3-tris-ethoxymethylureidomethyl)-1,1,3 ,3-Tetra-ethoxymethylurea, N,N′-bis-(1,1,3-tris-ethoxymethylureidomethyl)-1,3-bis-ethoxymethylurea, N,N′-bis-(1,1,3-tris-ethoxymethylureidomethoxymethyl)-1,3-bis-ethoxymethylurea, N,N,N′,N′,N″,N″-Hexakis-methoxymethyl-[1,3,5]triazine-2,4,6-triamine, N,N,N′,N′,N″ -Pentakis-methoxymethyl-[1,3,5]triazine-2,4,6-triamine, N,N,N′,N″-Tetrakis-methoxymethyl-[1,3,5]triazine-2,4,6-triamine, N,N,N′,N′,N″,N″-Hexakis-ethoxymethyl-[1,3,5]triazine-2,4,6-triamine, N,N,N′,N′,N″-Pentakis-ethoxymethyl-[1,3,5]triazine-2,4,6-tri Amine, N,N,N′,N″-tetrakis-ethoxymethyl-[1,3,5]triazine-2,4,6-triamine, N,N,N′,N′,N″,N″-hexakis-propoxymethyl-[1,3,5]triazine-2,4,6-triamine, N,N,N′,N′,N″-pentakis-propoxymethyl-[1,3,5]triazine-2,4,6-triamine, N,N,N′,N″-tetrakis-propoxymethyl-[1,3, 5) The following can be selected from the group consisting of triazine-2,4,6-triamine, N,N,N′,N′,N″,N″-hexakis-phenoxymethyl-[1,3,5]triazine-2,4,6-triamine, N,N,N′,N′,N″-pentakis-phenoxymethyl-[1,3,5]triazine-2,4,6-triamine, and N,N,N′,N″-tetrakis-phenoxymethyl-[1,3,5]triazine-2,4,6-triamine.

[0016] In these and other embodiments, the phloroglucinol resin (e) is of formula (I): [ka] (Wherein at least one of R1, R2, and R3 is combined with a second phloroglucinol unit to form a disubstituted methylene bridge, and the second of R1, R2, and R3 is a hydrogen atom or is combined with a third phloroglucinol unit to form another disubstituted methylene bridge, and the third of R1, R2, and R3 is a hydrogen atom). More specifically, the phloroglucinol resin can be solid. In one or more embodiments, the phloroglucinol resin can have the chemical structure as described above, and thus it can be seen that it can have an isopropylidene bridge as the chemical structure of the disubstituted methylene bridge. In other embodiments, the phloroglucinol resin can have the chemical structure as described above, and thus it can have a 2,2-disubstituted butane bridge as the chemical structure of the disubstituted methylene bridge. In still other embodiments, the phloroglucinol resin can have the chemical structure as described above, and thus it can have a 2,2-disubstituted 4-methylpentane bridge as the chemical structure of the disubstituted methylene bridge.) It has the structure.

[0017] Furthermore, it can be seen that the solid phloroglucinol resin used in the rubber composition can be a reaction product of phloroglucinol and a ketone in the presence of an acid catalyst. The ketone can be selected from the group consisting of acetone, methyl ethyl ketone (MEK), and methyl isobutyl ketone (MIBK).

[0018] Generally, it can be seen that the sulfur donating compound (f) can be sulfur.

[0019] One or more other aspects of the present invention can be found in a method for preparing the above rubber composition.

[0020] Still other aspects of the present invention can be found in the cured rubber composition prepared from the above rubber composition. It can be seen that other aspects of the present invention can be obtained by articles such as components of a tire including this cured rubber composition.

Embodiments for Carrying out the Invention

[0021] Truck tires and tires for other heavy vehicles consist of numerous elastic bands of rubber and expandable structures of composite materials. For example, the layer above the inner liner, which consists of thin woven fiber cords bonded to the rubber, is called the carcass or casing. Carcass and casing are synonymous terms. Many tire carcasses have one or two body plies. The tire carcass can incorporate woven steel, polyester, nylon, or rayon cords into the carcass rubber compound. The belt system can be positioned on top of (radially outward) the carcass portion during the tire construction process. The tread slab or cap portion can be positioned on top of (radially outward) the belt system and / or carcass. The tread portion is in contact with the road and is compounded to enhance the tire's performance characteristics and durability. Key characteristics include handling, static friction, rolling resistance, and wear resistance.

[0022] In this specification and in the claims, the following terms and expressions should be understood as shown below.

[0023] Unless otherwise shown in the examples or elsewhere, all numbers expressed herein and in the claims, such as amounts of substances, reaction conditions, times, quantified properties of substances, etc., should be understood to be modified in all cases by the term “approximately.” Furthermore, if a number in a table is provided in a claim, and most or many of the other numbers in the same table for the same properties, quantities, etc., are lower than the number provided, then that number is understood to mean “less than or equal to.” Conversely, if a number in a table is provided in a claim, and most or many of the other numbers in the same table for the same properties, quantities, etc., are higher than the number provided, then that number is understood to mean “greater than or equal to.”

[0024] All methods described herein may be performed in any suitable order unless otherwise indicated herein or otherwise clearly refuted by the context, or unless described in a particular order in the claims. Any and all examples or illustrative words provided herein (e.g., “like”) are intended solely to enable a better understanding of the invention and do not impose limitations on the scope of the invention unless otherwise stated in the claims.

[0025] Nothing in this specification should be construed as indicating that any element not described in the claims is essential for carrying out the invention.

[0026] The term "for instance" has the same meaning as "for example."

[0027] Any numerical range enumerated herein is understood to include all subranges within that range and any combination of various endpoints of such range or subrange.

[0028] When used herein, stoichiometric integer values ​​relate to molecular species, while stoichiometric non-integer values ​​relate to mixtures of molecular species based on molecular weight average, number average, or mole fraction.

[0029] In the following statements, all weight percentages are based on the total weight percentage of organic matter unless otherwise stated, and all ranges given herein include all subranges and / or any combination of ranges and / or subranges.

[0030] When used herein, “rubbery polymer” refers to an organic polymer containing a main chain comprising at least two carbon-carbon double bonds and one or more carbon atom chains, or a mixture thereof. In one embodiment of the present invention, the rubbery polymer may be a member of at least one selected from the group consisting of diene-based elastomers and rubbers. The rubbery polymer may be any of those well known in the art and described in numerous texts. ru .

[0031] The term "rubbery polymer" does not preclude the possibility that a portion of the polymer may be temporarily or permanently partially or completely crystalline. The terminology used in this description is, as far as possible, the same as that presented in the Vanderbilt Rubber Handbook; RF Ohm, ed.; RT Vanderbilt Company, Inc., Norwalk, CT; 1990 and the Manual For The Rubber Industry; T. Kempermann, S. Koch, J. Sumner, eds.; Bayer AG, Leverkusen, Germany; 1993.

[0032] The term "primary network" refers to the rubbery polymer network in a cure package that has been cross-linked by vulcanization using a cross-linking agent.

[0033] The term "interpenetrating network" refers to the polymerization of rubber compound components within a compound without covalent interactions with the primary network.

[0034] Some representative non-limiting examples of suitable rubbery polymers that constitute the rubber component of the composition include, but are not limited to, natural rubber (NR), synthetic polyisoprene (IR), polybutadiene (BR), various copolymers of butadiene, various copolymers of isoprene, solution styrene-butadiene rubber (SSBR), emulsion styrene-butadiene rubber (ESBR), ethylene-propylene polymer (EPDM), acrylonitrile-butadiene rubber (NBR), and combinations thereof. Natural rubber (NR) is understood to include rubber from various natural plant sources, including rubber trees, dandelions, guayule rubber, etc., but is not limited to these.

[0035] In the present invention, suitable monomers for preparing a rubbery polymer can be selected from the group consisting of conjugated dienes such as isoprene and 1,3-butadiene (unlimited examples); suitable vinyl aromatic compounds such as styrene and alpha-methylstyrene (unlimited examples); and combinations thereof. The rubbery polymer can be a sulfur-curable rubber. The diene-based elastomer or rubber can be selected to be at least one of cis-1,4-polyisoprene rubber, including natural rubber and synthetic polyisoprene rubber, more specifically natural rubber, styrene / butadiene copolymer rubber prepared by emulsion polymerization, styrene / butadiene rubber prepared by organic solution polymerization, 3,4-polyisoprene rubber, isoprene / butadiene rubber, styrene / isoprene / butadiene terpolymer rubber, cis-1,4-polybutadiene, medium vinyl polybutadiene rubber (35-50 percent vinyl), high vinyl polybutadiene rubber (50-75 percent vinyl), styrene / isoprene copolymer, styrene / butadiene / acrylonitrile terpolymer rubber and butadiene / acrylonitrile copolymer rubber prepared by emulsion polymerization. Styrene / butadiene rubber (ESBR) derived by emulsion polymerization, for example, having a relatively conventional styrene content of 20-28 percent bound styrene, or ESBR having a moderate to relatively high bound styrene content, i.e., 28-45 percent bound styrene, for some applications, can also be considered as diene-based rubbers used in the present invention. Styrene / butadiene / acrylonitrile terpolymer rubber prepared by emulsion polymerization containing 2-40 weight percent bound acrylonitrile in the terpolymer can also be considered as a diene-based rubber used in the present invention.

[0036] Rubber-like polymers can also be functionalized rubbers. Functionalized rubbers are rubbers modified with at least one functional group containing an atom other than carbon or hydrogen. Functional groups are typically alkoxysilyl groups, tin-containing groups, amino groups, hydroxyl groups, carboxylic acid groups, polysiloxane groups, epoxy groups, etc., or combinations of these functional groups. Functional groups can be introduced into rubber-like polymers during the preparation of synthetic rubbers by copolymerizing the monomers used to create the rubber with monomers containing the functional group, initiators, or terminal units.

[0037] Alternatively, rubber polymers can be modified with functional groups by grafting functional groups onto already formed rubber-like polymers.

[0038] Functionalized rubbery polymers can be used in combination with other unfunctionalized rubbery polymers. The mixture may contain at least 5 to about 95 parts per 100 parts of rubber of at least one styrene-butadiene rubber functionalized with at least one group selected from phthalocyanino, tin-containing, hydroxyl, epoxy, carboxylate, amino, alkoxysilyl, and sulfido groups, and having a styrene content of 0 to about 12 weight percent, and at least one further rubbery polymer at about 5 to about 95 parts per 100 parts of rubber. Functionalized rubbery polymers (rubber) generally have a glass transition temperature (Tg) in the unvulcanized state according to a DSC of -120 to -10°C.

[0039] In another embodiment of the present invention, the rubbery polymer may be a diene polymer functionalized or modified with an alkoxysilane derivative. Styrene-butadiene rubber prepared by solution polymerization of a silane-functionalized organic and 1,4-polybutadiene rubber prepared by solution polymerization of a silane-functionalized organic may be used. These rubber compositions are known; see, for example, U.S. Patent No. 5,821,290, the entire content of which is incorporated herein by reference.

[0040] In yet another embodiment of the present invention, the rubbery polymer is a diene polymer functionalized or modified with a tin derivative. Tin-coupled copolymers of styrene and butadiene can be prepared, for example, by introducing a tin coupling agent during the copolymerization reaction of styrene and 1,3-butadiene monomer in an organic solvent solution, usually at or near the end of the polymerization reaction. Such tin-coupled styrene-butadiene rubbers are well known to those skilled in the art; see, for example, U.S. Patent No. 5,268,439, the entire content of which is incorporated herein by reference. In fact, at least about 50 percent, preferably about 60 to about 85 percent, of tin is bonded to the butadiene units of the styrene-butadiene rubber to form tin-dienyl bonds.

[0041] The properties of natural rubber (NR) are particularly useful in the manufacture of tires for heavy vehicles, buses, and trucks. One important reason for this is the combination of natural rubber's high cis-1,4-polyisoprene content, its large molecular weight, and its ability to undergo strain-induced crystallization. In one embodiment of the present invention, the rubbery polymer comprises natural rubber or a mixture of natural and synthetic rubber. Preferably, when the rubbery polymer is a mixture of rubbers, the rubber formulation must contain at least about 10 weight percent of natural rubber, preferably about 30 weight percent of natural rubber, more preferably at least about 50 weight percent of natural rubber, and even more preferably at least about 70 weight percent of natural rubber.

[0042] The uncured rubber composition preferably contains a reinforcing filler. The reinforcing filler should be a material whose modulus is higher than that of the rubbery polymer in the rubber composition and should be able to absorb stress when the cured rubber composition is stretched. The reinforcing filler can be a material reactive with the organosilane coupling agent and may include fibers, fine particles, and sheet-like structures. They may consist of inorganic minerals, silicates, silica, clay, ceramics, and diatomaceous earth. The reinforcing filler reactive with the organosilane coupling agent may be in the form of separate particles or aggregates or clumps of particles. The organosilane coupling agent may be reactive with the surface of the filler. Precipitated silica in the form of fine particles can be useful as a reinforcing filler reactive with the organosilane coupling agent, especially when the silica has a reactive surface silanol. Silica may be supplied in a hydrated form or converted to a hydrated form by reaction with water. The reinforcing filler can be used in an amount of 1 to 150 parts per 100 parts of the rubber-like polymer, more specifically 25 to 90 parts per 100 parts of the rubber-like polymer, or more specifically 40 to 80 parts per 100 parts of the rubber-like polymer.

[0043] Typical non-limiting examples of organosilane coupling agents and reactive reinforcing fillers include at least one metalloid oxide or metal oxide, such as calcined silica, precipitated silica, titanium dioxide, aluminosilicates, alumina, and siliceous materials including clay and talc, as well as combinations thereof.

[0044] In one or more embodiments of the present invention, the reinforcing filler may be silica, used alone or in combination with one or more other fillers, such as organic and / or inorganic fillers that do not react with organosilane coupling agents. Typical non-limiting examples include combinations of silica and carbon black for reinforcing fillers for various rubber products, including non-limiting examples for tire treads. Alumina can be used alone or in combination with silica. In this specification, the term "alumina" means aluminum oxide or Al2O3. The use of alumina in rubber compositions is known; see, for example, U.S. Patent No. 5,116,886 and European Patent No. 631,982, both of which are incorporated herein by reference in their entirety.

[0045] Reactive reinforcing fillers for organosilane coupling agents can be used as carriers for organosilane coupling agents. Other fillers that can be used as carriers are non-reactive with organosilane coupling agents. The non-reactivity of a filler is indicated by the ability of more than 50 percent of the loaded silane of the organosilane coupling agent to be extracted using an organic solvent. The extraction procedure is described in U.S. Patent No. 6,005,027, the full contents of which are incorporated herein by reference. Representative examples of non-reactive carriers include, but are not limited to, porous organic polymers and carbon black. The amount of organosilane coupling agent that can be loaded onto the carrier is preferably 0.1 to 70 percent, more preferably 10 to 50 percent, based on the total weight of the carrier and organosilane coupling agent.

[0046] In one non-limiting embodiment of the present invention, other fillers that can be mixed with the organosilane coupling agent and the reactive reinforcing filler may be intrinsically inert to the organosilane coupling agent when mixed, as in the case of carbon black or an organic polymer. In another embodiment, at least two reinforcing fillers that are reactive with the organosilane coupling agent can be mixed together and may be reactive with it. Reinforcing fillers having metalloid hydroxyl surface functionality, such as silica and other siliceous fine particles having surface silanol functionality, can be used in combination with reinforcing fillers containing metallic hydroxyl surface functionality, such as alumina and other siliceous fillers.

[0047] In one embodiment of the present invention, precipitated silica is used as a reinforcing filler for reactivity with an organosilane coupling agent. In a preferred embodiment of the present invention, the silica filler can be characterized by having a Brunauer, Emmett, and Teller (BET) surface area in the range of about 40 to about 600 m² / g, preferably in the range of about 50 to about 300 m² / g, and more preferably in the range of about 100 to about 220 m² / g, as measured using nitrogen gas. The BET method for measuring surface area, as described in the Journal of the American Chemical Society, Vol. 60, p. 304 (1930), is the method used in the present invention. In yet another preferred embodiment, the silica is characterized by having a dibutyl phthalate (DBP) absorption value typically in the range of about 100 to about 350, preferably in the range of about 150 to about 300, and more preferably in the range of about 200 to about 250. In other embodiments, the reinforcing filler reactive with the organosilane coupling agent may be alumina and aluminosilicate fillers, which may have a CTAB surface area in the range of about 80 to about 220 m² / g. The CTAB surface area is the external surface area determined by cetyltrimethylammonium bromide at a pH of about 9; a method for measuring this is described in ASTM D 3849.

[0048] The mercury porosity surface area is the specific surface area determined by mercury porosimetry. In this technique, mercury penetrates the pores of the sample after heat treatment to remove volatile substances. In a more specific embodiment, a 100 milligram sample is used under set conditions, volatile substances are removed over 2 hours at 105°C and ambient atmospheric pressure, and a measurement range from ambient pressure up to 2000 bar is used. Such evaluation can be performed according to the method described by Winslow et al. in ASTM bulletin, p. 39 (1959), or according to DIN 66133; a CARLO-ERBA Porosimeter 2000 can be used for such evaluation. Useful reinforcing fillers reactive with silane include silica having an average mercury porosity specific surface area in the range of about 100 to about 300 m² / g, preferably about 150 to about 275 m² / g, and more preferably about 200 to about 250 m² / g.

[0049] A suitable pore size distribution for reinforcing fillers reactive with organosilane coupling agents, including non-limiting examples of silica, alumina, and aluminosilicates, is considered in the present invention to be 5 percent or less of pores with a diameter of less than 10 nm; about 60 to about 90 percent of pores with a diameter of 10 to 100 nm; about 10 to about 30 percent of pores with a diameter of 100 to 1,000 nm; and about 5 to about 20 percent of pores with a diameter greater than 1,000 nm, according to such mercury porosity evaluation. These reinforcing fillers can usually be expected to have an average final particle size in the range of about 0.005 to about 0.075 mm, preferably about 0.01 to about 0.05 mm, as determined by electron microscopy, although the particles may have a smaller or larger average diameter. Various commercially available silicas, such as those available from PPG Industries under the trademark HI-SIL, particularly HI-SIL 210 and 243; silicas available from Solvay, such as ZEOSIL 1165MP; silicas available from Evonik, such as VN2 and VN3, etc.; and silicas available from Huber, such as HUBERSIL 8745, can be used in this invention.

[0050] In one embodiment of the present invention, the filler may contain an organosilane coupling agent-reactive reinforcing filler in an amount of about 15 to about 95 weight percent of precipitated silica, alumina and / or aluminosilicate, preferably silica, and correspondingly about 5 to about 85 weight percent of carbon black having a CTAB value in the range of about 80 to about 150. More preferably, the filler may contain about 60 to about 95 weight percent of the silica, alumina and / or aluminosilicate, preferably silica, and correspondingly about 40 to about 50 weight percent of carbon black. The precipitated silica, alumina and / or aluminosilicate filler and carbon black can be pre-blended or blended together during the production of the vulcanized rubber. When used, the carbon black may be added in an amount ranging from 0.5 to 10 parts per 100 parts of the rubbery polymer.

[0051] The tire tread is conventionally compounded with carbon black filler. Carbon black provides exceptional wear resistance to the tread, leading to longer-lasting tires with higher mileage. When silica is used as a filler, the dispersion of silica throughout the rubber matrix can reverse into high-friction silica-silica and rubber-silica interactions. This friction can interfere with tire properties, such as rolling resistance. Adding conventional silanes to the tire compound can reduce rolling resistance by limiting the internal friction of silica-silica interactions and immobilizing polymer chains on the silica surface. However, without wanting to be bound by theory, as discussed in JI Cuneen, Rubber Chemistry and Technology, Vol. 33, p. 445, 1960; and JI Cuneen and FW Shipley, Journal of Polymer Science, Vols. 36, 77, 1959, it is thought that the sulfur-mediated bonding of silanes to rubber chains can increase the trans content of natural rubber. This would likely have a negative impact on performance properties such as wear resistance. Furthermore, severely restricting the mobility of the chain may affect the natural rubber's ability to undergo stress-induced crystallization, potentially impairing its wear resistance and tear resistance.

[0052] Conventional silanes react directly with polymer chains, degrading critical properties of the primary rubber network. Standard amino resin-resorcinol systems can reinforce the primary polymer network with interpenetrating networks, but this can lead to irreversible distortion with a decrease in critical properties. Without being bound by theory, it is believed that organosilanes react with HMMM and phloroglucinol resins to create interpenetrating networks, which reinforce load transfer from one filler to another and reduce friction between filler aggregates. The concentration of thermosetting interpenetrating networks at the filler interface attracts thermosetting resins with minimal strain.

[0053] Rolling resistance can be reduced by hydrophobizing the silica. Increasing the effective filler volume enhances wear resistance and tear resistance. Furthermore, the secondary polymer network can increase the reinforcement and stiffness of the resulting tread under static and dynamic deformation.

[0054] The polymerization of this load-bearing-path reinforcing interpenetrating network is thought to grow from the reinforcing filler surface, particularly the silica surface, after reaction with organosilane coupling agents. These organosilane coupling agents can function as initiators or co-initiators during the rubber mixing and / or curing process. The resulting reinforcing interpenetrating network can create additional points of physical and chemical chain entanglement with the rubber phase in the immediate surroundings of the filler. These entanglements, together with the resulting interpenetrating polymer network and silica, are thought to create a hierarchical structure whose modulus gradient is useful for load transfer from the rubbery polymer chains to the silica during static and dynamic deformation, thereby increasing tear and wear resistance and reducing abrasion. Polymerization of the interpenetrating polymer network from the filler surface can create a network structure on the filler surface, increasing the effective filler volume. This network structure and effective filler volume result in further reinforcement and also contribute to improved wear resistance.

[0055] Without being bound by theory, it is believed that such polymer networks are formed from reinforcing interpenetrating polymer network methylene donor compounds and phloroglucinol resins. As those skilled in the art will understand, the interpenetrating network can also be called a secondary network. Without being bound by theory, a secondary network means two separate polymer networks that are indistinguishable on a macroscale. Phloroglucinol resins forming load-bearing path reinforcing interpenetrating networks include, but are not limited to, phloroglucinol linked by disubstituted methylene bonds.

[0056] In one embodiment of the present invention, the methylene donor compound is an amino resin. The amino resin can be a resin formed from the reaction of a compound containing -NH, formaldehyde, and an alcohol. More preferably, the amino resin is derived from 2,4,6-triamino-1,3,5-triazine, benzoguanamine, urea, glycoluryl, and poly(meth)acrylamide.

[0057] The methylene donor compound can be used in an amount of 0.1 to 30 parts of the methylene donor compound per 100 parts of the rubbery polymer, more specifically 0.2 to 15 parts of the methylene donor compound per 100 parts of the rubbery polymer, and even more specifically 0.3 to 10 parts of the methylene donor compound per 100 parts of the rubbery polymer.

[0058] Representative and non-limiting examples of methylene donor compounds include 1,1,3,3-tetra-methoxymethylurea, 1,3,3-tris-methoxymethylurea, 1,3-bis-methoxymethylurea, 1,1-bis-methoxymethylurea, 1,1,3,3-tetra-ethoxymethylurea, 1,3,3-tris-ethoxymethylurea, 1,3-bis-ethoxymethylurea, 1,1-bis-ethoxymethylurea, 1,1,3,3-tetra-propoxymethylurea, 1,3,3-tris-propoxymethylurea, l,3-bis-propoxymethylurea, and 1,1-bis-propoxymethylurea. Tylurea, 1,1,3,3-tetra-butoxymethylurea, 1,1,3,3-tetra-phenoxymethylurea, N-(l,3,3-tris-ethoxymethylureidomethyl)-1,1,3,3-tetra-ethoxymethylurea, N,N'-bis-(1,1,3-tris-ethoxymethylureidomethyl)-1,3-bis-ethoxymethylurea, N,N'-bis-(1,1,3-tris-ethoxymethylureido-methoxymethyl)-1,3-bis-ethoxymethylurea, N,N,N',N',N",N”-hexakis-methoxymethyl-[l,3,5]tri Azin-2,4,6-triamine, N,N,N',N',N”-pentakis-methoxymethyl-[1,3,5]triazine-2,4,6-triamine, N,N,N',N”-tetrakis-methoxymethyl-[l,3,5]triazine-2,4,6-triamine, N,N,N,,N',N”,N”-hexakis-ethoxymethyl-[l,3,5]triazine-2,4,6-triamine, N,N,N',N',N”-pentakis-ethoxymethyl-[l,3,5]triazine-2,4,6-triamine, N,N,N',N”-tetrakis-ethoxymethyl-[ [l,3,5]triazine-2,4,6-triamine, N,N,N',N',N”,N”-hexakis-propoxymethyl-[l,3,5]triazine-2,4,6-triamine, N,N,N',Nl,N”-pentakis-propoxymethyl-[l,3,5]triazine-2,4,6-triamine, N,N,N',N”-tetrakis-propoxymethyl-[l,3,5]triazine-2,4,6-triamine, N,N,N',N',N”,N”-hexakis-phenoxymethyl-[1,3,5]triazine-2,4,6-triamine, N,N,N',N',N”-Pentakis-phenoxymethyl-[l,3,5]triazine-2,4,6-triamine, N,N,N',N”-Tetrakis-phenoxymethyl-[l,3,5]triazine-2,4,6-triamine, 1,3,4,6-Tetrakis-methoxymethyl-tetrahydro-imidazo[4,5-d]imidazole-2,5-dione, 1,3,4,6-Tetrakis-ethoxymethyl-tetrahydro-imidazo[4,5-J]imidazole-2,5-dione, 1,3,4,6-Tetrakis-propoxymethyl-tetrahydro-imidazo[4,5-d]imidazole-2,5-dione, l, These are 3,4,6-tetrakis-phenoxymethyl-tetrahydro-imidazo[4,5-d]imidazole-2,5-dione, 1,3,4-tris-ethoxymethyl-tetrahydro-imidazo[4,5-d]imidazole-2,5-dione, 1,4-bis-ethoxymethyl-tetrahydro-imidazo[4,5-d]imidazole-2,5-dione, 1,3,4-tris-methoxymethyl-tetrahydro-imidazo[4,5-d]imidazole-2,5-dione, and 1,3,4-tris-phenoxymethyl-tetrahydro-imidazo[4,5-d]imidazole-2,5-dione.

[0059] Methylene donor compounds can be obtained commercially. For example, amino resins can be purchased commercially from PERFERE, formerly INEOS Melamine GmbH, under the trade names RESIMENE® 747 ULF, RESIMENE® 755, RESIMENE® 757, RESIMENE® 764, RESIMENE® CE 8824 ULF, and MAPRENAL® UF 134 / 60B.

[0060] In one example, the organosilane coupling agent has general formula (Ia): (R 2 O) a (R 3 ) 3-a Si(R 4 XH) In the formula, each R2 is independently hydrogen, an alkyl group having 1 to 10 carbon atoms and optionally having at least 1 oxygen atom, a cycloalkyl group having 3 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 12 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms, and even more preferably ethyl; each R3 is independently an alkyl group having 1 to 3 carbon atoms or phenyl; R4 is an alkylene group having 1 to 10 carbon atoms and optionally having at least 1 oxygen atom, a cycloalkylene group having 3 to 10 carbon atoms, an alkenylene group having 2 to 10 carbon atoms, an arylene group having 6 to 12 carbon atoms, or an aralkylene group having 7 to 14 carbon atoms, more preferably an alkylene group having 1 to 6 carbon atoms, and even more preferably propylene; X is 1 or more, preferably 2 to 10, and even more preferably an average of 2 to 4 sulfur atoms.

[0061] Typical non-limiting examples of silanes containing the functional group of formula (Ia) are 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyltripropoxysilane, 3-mercaptopropyldimethoxyethoxysilane, 3-mercaptopropylmethyldiethoxysilane, 3-mercaptopropyldimethylethoxysilane, mercaptomethyltriethoxysilane, 4-mercapto-3,3-dimethylbutyltriethoxysilane, 3-mercaptopropylethoxy-[l,3,2]dioxasilinane, and 3-mercaptopropyl This includes ropyl-(3-hydroxy-2-methylpropoxy)-5-methyl-[l,3,2]dioxasilinane, 6-mercaptohexyltriethoxysilane, 3-aminopropyltriethoxysilane, N-ethyl-3-aminopropyltriethoxysilane, N-methyl-3-aminopropyltriethoxysilane, N-ethyl-3,3-dimethyl-4-aminobutyltriethoxysilane, n-phenyl-3-aminopropyltriethoxysilane, 3-ureidopropyltriethoxysilane, 3-ureidopropyltrimethoxysilane, and mixtures thereof.

[0062] The silane coupling agent of formula (Ia) can be used in an amount of 0.05 to 30 parts, more specifically 0.5 to 15 parts, and even more specifically 1 to 10 parts of the mercapto silane coupling agent per 100 parts of the rubbery polymer.

[0063] The organosilane of formula (Ia) can be obtained commercially. For example, the mercapto silane coupling agent can be commercially purchased from Momentive Performance Materials, Inc. under the trade names Si263, Usi-5301, Silquest A-189, Z-6062, KBM-803. MTMO, GENIOSIL® GF 70 and S 810.

[0064] In another example, the organosilane coupling agent is a silane having the general formula (Ib): (R 2 O) a R 3 3-a Si(R 4 )X 1 R 4 Si(R 3 3-a (R 2 O) a ) In the formula, each R2 is independently hydrogen, an alkyl group having 1 to 10 carbon atoms and optionally having at least 1 oxygen atom, a cycloalkyl group having 3 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 12 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms, and even more preferably ethyl; each R3 is independently an alkyl group having 1 to 3 carbon atoms or phenyl; R4 is an alkylene group having 1 to 10 carbon atoms and optionally having at least 1 oxygen atom, a cycloalkylene group having 3 to 10 carbon atoms, an alkenylene group having 2 to 10 carbon atoms, an arylene group having 6 to 12 carbon atoms, an aralkylene group having 7 to 14 carbon atoms, more preferably an alkylene group having 1 to 6 carbon atoms, and even more preferably propylene; X 1 This consists of one or more sulfur atoms, preferably 2 to 10, and more preferably an average of 2 to 4.

[0065] Typical non-limiting examples of silanes containing the functional group of formula (Ib) are bis(tripropoxysilylpropyl)tetrasulfide; bis(triethoxysilylpropyl)tetrasulfide; bis(trimethoxysilylethyl)tetrasulfide; bis(trimethoxymethyl)tetrasulfide; bis(tripropoxysilylpropyl)disulfane; bis(triethoxysilylethyl)tetrasulfide; bis(triethoxysilylmethyl)tetrasulfide; bis(3-triethoxysilylpropyl)disulfane; bis[3-(triethoxysilyl)pro This includes [pyrus]-disulfide; bis[3-(triethoxysilyl)propyl]persulfide; 3,3'-bis-(triethoxysilylpropyl)disulfide; bis[3-(triethoxysilyl)propyl]perdisulfide; bis(triethoxysilyl)-4,5-dithiooctane; bis(tripropoxysilylpropyl)disulfide; bis(triethoxysilylpropyl)disulfide; bis(trimethoxysilylethyl)disulfide; bis(triethoxysilylethyl)disulfide; and bis(triethoxysilylmethyl)disulfide.

[0066] The silane coupling agent of formula (Ib) can be used in an amount of 0.05 to 30 parts of organosilane coupling agent per 100 parts of rubbery polymer, more specifically 0.5 to 15 parts of organosilane coupling agent per 100 parts of rubbery polymer, and even more specifically 1 to 10 parts of organosilane coupling agent per 100 parts of rubbery polymer.

[0067] Organosilanes of formula (Ib), where X1 represents an average of four sulfur atoms, are commercially available. For example, the Si69 coupling agent can be commercially purchased from Evonik. Crosile 69 TESPT can be purchased from Guangzhou Ecopower. Z6940 can be purchased from Owen Corning Corporation. A-1289 can be purchased from Momentive Performance Materials, Inc. KBE-846 can be purchased from Shin-Etsu Co. In addition, organosilanes of formula (Ib), where X1 represents an average of two sulfur atoms, can be purchased under trade names Si 75, HP 1589, JH-S75, and TESPD.

[0068] In another embodiment, the organosilane is covalently bonded to a hydrogen-containing compound.

[0069] The rubber composition of the present invention may further contain a phloroglucinol resin. The phloroglucinol resin may be solid under standard conditions. A solid phloroglucinol resin is generally given by formula (II): [ka] The compound contains multiple phloroglucinol units as defined by (wherein at least one of R1, R2, and R3 is bonded to a second phloroglucinol unit to form a disubstituted methylene bridge, the second of R1, R2, and R3 being a hydrogen atom, or bonded to a third phloroglucinol unit to form another disubstituted methylene bridge, the third of R1, R2, and R3 being a hydrogen atom). The structure used in formula (II) is intended to represent the fact that the disubstituted methylene bridge of R1, R2, or R3 can be bonded to the 2nd, 4th, or 6th position on the aromatic ring. Also, the hydrogen atoms of R1, R2, or R3 are located at the 2nd, 4th, or 6th position. As will be apparent to those skilled in the art, any carbon atom in the aromatic ring that is not bonded to a hydroxyl group can be bonded to R1, R2, or R3, and may contain a hydrogen atom or be part of a disubstituted methylene bridge.

[0070] In general, a disubstituted methylene bridge is bonded to at least two C1-C10 alkyl groups extending from the methylene bridge. In another embodiment, the methylene bridge contains at least two C1-C5 alkyl groups extending from it. In yet another embodiment, the methylene bridge contains at least two C1-C4 alkyl groups extending from it. In yet another embodiment, the methylene bridge contains at least two C1-C3 alkyl groups extending from it. In yet another embodiment, the methylene bridge contains at least two C1-C2 alkyl groups extending from it.

[0071] More specifically, the phloroglucinol resin of the present invention may be described as shown in formula (III). [ka] In the formula, R1 of the phloroglucinol unit on the left is replaced by a disubstituted methylene bridge shown at position 2, and R3 of the phloroglucinol unit on the right is replaced at position 5. R3 on the left and R1 on the right may also be the same disubstituted methylene bridge as shown herein, or they may be a hydrogen atom, and R2 may be a hydrogen atom as shown in this embodiment. R4 and R5 may be the same or different and are alkyl groups. In one embodiment, both R4 and R5 may be methyl groups, and the disubstituted methylene bridge formed therein is an isopropylidene bridge. In another embodiment, R4 may be an ethyl group and R5 may be a methyl group, and the disubstituted methylene bridge formed therein is a 2,2-disubstituted butane bridge. In yet another embodiment, R4 may be an isopropyl group and R5 may be a methyl group, and the disubstituted methylene bridge formed therein is a 2,2-disubstituted 4-methylpentane bridge.

[0072] The resin is distributed as dimers, trimers, tetramers, pentamers, and more than 100 parts of polymer, and monomers can function with the resin in amounts of less than 40%. The phloroglucinol resin can be used in amounts of 0.1 to 15 parts of phloroglucinol resin per 100 parts of rubbery polymer, more specifically 0.5 to 10 parts of phloroglucinol resin per 100 parts of rubbery polymer, and even more specifically 1 to 5 parts of phloroglucinol resin per 100 parts of rubbery polymer.

[0073] Sulfur-donating compounds can also be incorporated into rubber compositions. Sulfur-donating compounds can be used to crosslink rubbery polymers to form a crosslinked primary network. While we do not wish to be bound by theory, sulfur-donating compounds are thought to donate sulfur atoms under curing conditions. Sulfur-donating compounds generally have more than two sulfur atoms that bond to each other to form chains of sulfur atoms. Polysulfides and elemental sulfur, preferably sulfur S8, are sulfur-donating compounds.

[0074] Vulcanization can be carried out in the presence of sulfur-donating compounds, often referred to as vulcanizing agents. These react with rubbery polymers containing carbon-carbon double bonds to form crosslinked or cured rubber. Some non-limiting examples of suitable sulfur vulcanizing agents include, for example, elemental sulfur (free sulfur) or, non-limiting examples, sulfur-donating compounds such as amino disulfides, polymeric polysulfides, or sulfur-olefin adducts. These, as well as other known and conventional vulcanizing agents, are added in typical amounts during the mixing step, known as the productive mixing step, in methods for preparing rubber compositions.

[0075] Sulfur-donating compounds are generally used at concentrations of about 0.1 to about 5 phr, more preferably about 1 to about 3 phr, and even more preferably about 1.5 to about 2.5 phr.

[0076] The rubber composition may be compounded with other commonly used additives such as retarders and accelerators, process additives such as oils, resins such as tackifying resins, plasticizers, pigments, fatty acids, zinc oxide, waxes, antioxidants and ozone degradation inhibitors, mixing accelerators, and the like. Depending on the intended use of the rubber composition, these and / or other rubber additives are used in conventional amounts.

[0077] Vulcanization accelerators may also be used if desired. Non-limiting examples of vulcanization accelerators include benzothiazoles, alkyl thiuram disulfides, guanidine derivatives, and thiocarbamates. Other examples of such accelerators include, but are not limited to, mercaptobenzothiazole, tetramethylthiuram disulfide, tetrabenzylthiuram disulfide, benzothiazole disulfide, diphenylguanidine, zinc dithiocarbamate, alkylphenol disulfide, zinc butylxanate, N-dicyclohexyl-2-benzothiazole sulfenamide, N-cyclohexyl-2-benzothiazole sulfenamide, N-oxydiethylenebenzothiazole-2-sulfenamide, N,N-diphenylthiourea, dithiocarbamyl sulfenamide, N,N-diisopropylbenzothiazole-2-sulfenamide, zinc-2-mercaptotolimidazole, dithiobis(N-methylpiperazine), dithiobis(N-beta-hydroxyethylpiperazine), and dithiobis(dibenzylamine). In another embodiment, other additional sulfur donors include, for example, thiuram and morpholine derivatives. In more specific embodiments, representative examples of such donors include, but are not limited to, dimorpholine disulfide, dimorpholine tetrasulfide, tetramethylthiuram tetrasulfide, benzothiadyl-2,N-dithiomorpholide, thioplast, dipentamethylenethiuram hexasulfide, and disulfide caprolactam.

[0078] Accelerators can be used to control the time and / or temperature required for vulcanization and to improve the properties of the vulcanized product. In one embodiment of the present invention, a single accelerator system, i.e., a primary accelerator, can be used. In another embodiment, conventionally and preferably, the primary accelerator is used in a total amount ranging from about 0.5 to about 4 phr, preferably from about 0.8 to about 2.0 phr. In a preferred embodiment, a combination of primary and secondary accelerators can be used, with the secondary accelerator being used in smaller amounts, for example, from about 0.05 to about 3 phr, to activate and improve the properties of the vulcanized product. In yet another embodiment, a delayed action accelerator can also be used. In yet yet another embodiment, a vulcanization retarder can also be used. Suitable types of accelerators include, in non-limiting examples, amines, disulfides, guanidines, thioureas, thiazoles, thiurams, sulfenamides, dithiocarbamates, xanthetes, and combinations thereof. In a preferred embodiment, the primary accelerator is a sulfenamide. In another embodiment, if a second accelerator is used, the secondary accelerator can be guanidine, dithiocarbamate, or a thiuram compound such as tetrabenzyl thiuram disulfide, used at a level of, for example, about 0.1 to about 0.3 phr, more preferably about 0.2 phr.

[0079] An optional tackifying resin can be used at a level of about 0.5 to about 10 phr, preferably about 1 to about 5 phr. In a preferred embodiment, the amount of processing aid is in the range of about 1 to about 50 phr. Suitable processing aids include, non-limited examples, aromatic, naphthenic, and / or paraffinic processing oils and combinations thereof. In yet another embodiment, a preferred amount of antioxidant is about 1 to about 5 phr. Typical antioxidants include, non-limited examples, diphenyl-p-phenylenediamine and others, for example, those disclosed in the Vanderbilt Rubber Handbook (1978), pages 344-346, which are incorporated herein by reference. In yet another embodiment, a preferred amount of ozone degradation inhibitor is in the range of about 1 to about 5 phr. A preferred amount of an optional fatty acid, which may include, non-limited example, stearic acid, is in the range of about 0.5 to about 3 phr.

[0080] The preferred amount of zinc oxide is in the range of about 2 to about 5 phr. The preferred amount of wax, such as microcrystalline wax, is in the range of about 1 to about 5 phr. The preferred amount of peptider is in the range of about 0.1 to about 1 phr. Suitable peptiders, in non-limiting examples, include pentachlorothiophenol, dibenzamide diphenyl disulfide, and combinations thereof.

[0081] In one embodiment of the present invention, the rubber composition contains a phloroglucinol resin, and the rubber composition preferably comprises (a) at least one rubbery polymer used to form a primary network, (b) at least one reinforcing filler that can react with an organosilane coupling agent, (c) at least one methylene donor compound that forms a load-bearing path reinforcing interpenetrating network, (d) at least one organosilane coupling agent that can react with the reinforcing filler, (e) at least a phloroglucinol resin, and (f) at least one sulfur-donating compound, particularly sulfur (S 8 )ofThe rubbery polymer may contain one or more rubber components, with the total rubber components amounting to approximately 100 phr (parts per hundred parts rubber). In one embodiment of the present invention, natural rubber should constitute approximately 50 to 100 phr, preferably approximately 75 to 100 phr, of the primary polymer blend portion of the rubber composition. The reinforcing filler may comprise approximately 1 to approximately 150 phr, preferably approximately 15 to 90 phr, and more preferably approximately 20 to 55 phr of the rubber composition. In one embodiment of the present invention, the reinforcing filler is silica, preferably precipitated silica. The organosilane coupling agent itself and / or the material for forming the load-bearing path reinforcing interpenetrating network (methylene donors and phloroglucinol resins forming the network) may constitute approximately 6 to 50% of the weight portion of the reinforcing filler in the formulation, preferably approximately 8 to 25% of the weight of the reinforcing filler, and more preferably approximately 12 to 25% of the weight of the reinforcing filler in the formulation.

[0082] Therefore, in one or more embodiments, the rubber composition is: (a) Rubber-like polymers or blends of polymers; (b) at least one organosilane coupling agent; (c) At least one reinforcing filler that is reactive with an organosilane coupling agent; (d) at least one methylene donor resin; (e) at least one phloroglucinol resin; and (f) Depending on the case, at least one sulfur-donating compound Includes.

[0083] In another embodiment, the rubber composition comprises about 25 to about 95 weight percent of a rubbery component based on the total weight of the rubber composition, about 2 to about 70 weight percent of an organosilane coupling agent and a reactive reinforcing filler based on the total weight of the rubber composition, about 0.2 to about 25 weight percent of a methylene donor resin based on the total weight of the rubber composition, about 0.2 to about 25 weight percent of a phloroglucinol resin based on the total weight of the rubber composition, and about 0.2 to about 5 weight percent of a sulfur-donating compound based on the total.

[0084] In the cured rubber composition, the primary polymeric network is cured by raising the temperature of the rubber composition for a time sufficient to react the rubber polymer or rubber polymer blend (a) with at least one sulfur-donating compound, thereby forming a crosslinked rubber polymer or crosslinked polymer blend.

[0085] In another embodiment of the present invention, a method for providing the rubber composition described herein comprises mixing an effective amount of at least one reinforcing filler, at least one methylene donor resin, at least one organosilane coupling agent, at least one phloroglucinol resin, and optionally at least one sulfur-donating compound with a rubbery component such as natural rubber. In one embodiment of the method according to the present invention, the effective amount of the organosilane coupling agent may be in the range of about 0.2 to about 20, preferably about 0.5 to about 15, more preferably about 2 to about 10 weight percent based on the total weight of the rubber composition. The effective amount of the rubbery component may be in the range of about 25 to about 95, preferably about 50 to about 90, more preferably about 60 to about 80 weight percent based on the total weight of the rubber composition. The effective amount of the reinforcing filler reactive with the organosilane coupling agent may be in the range of about 2 to about 70, preferably about 5 to about 55, more preferably about 20 to about 50 weight percent based on the total weight of the rubber composition. The effective amount of organic resin can be in the range of about 0.2 to about 25 weight percent, preferably about 2 to about 15 weight percent, and more preferably about 5 to about 10 weight percent, based on the total weight of the rubber composition. The effective amount of active hydrogen-containing compound (e) can be in the range of about 0.2 to about 25 weight percent, preferably about 2 to about 15 weight percent, and more preferably about 5 to about 10 weight percent, based on the total weight of the rubber composition. The effective amount of sulfur-donating compound can be in the range of about 0.2 to about 5, preferably about 0.5 to about 2.5, and more preferably about 1 to about 2 weight percent, based on the total weight of the rubber composition.

[0086] In yet another embodiment of the present invention, a method for preparing a rubber composition may optionally include curing the rubber composition before, during, and / or after molding. The vulcanized rubber composition should contain a sufficient amount of load-bearing path-reinforcing interpenetrating mesh to contribute to a higher modulus and better wear.

[0087] In one embodiment of the present invention, the organosilane coupling agent is added separately to a process mixture containing a rubbery polymer component. The reinforcing filler and the organosilane coupling agent can be considered to couple or react in situ to form a reinforcing filler in which the organosilane coupling agent is chemically bonded with the filler.

[0088] In one embodiment of the present invention, a method for preparing a rubber composition comprises several steps. In a non-productive step (i), a rubbery component, a reinforcing filler, a methylene donor resin, and an organosilane are mixed under reactive-mechanical-working conditions. As used herein, the expression “reactive-mechanical-working conditions” should be understood to mean high temperature, residence time, and shear conditions within a machining apparatus such as an extruder, a meshing mixer, or a tangential mixer, which are sufficient to cause one or more of the following:

[0089] The hydrolysis reaction step of the organosilane coupling agent by water present on the reinforcing filler may form alkoxymethylamino-functionalized silanols. The reaction step between these silanols and the reinforcing filler may form covalent chemical bonds with the filler. Decomposition of the reinforcing filler aggregates into smaller aggregates and / or individual filler particles is possible. When the reinforcing filler is dispersed in a rubbery polymer, it may covalently bond to the condensed alkoxymethylamino-functionalized silanes after hydrolysis.

[0090] In non-productive step (ii), the methylene donor and the phloroglucinol resin are added to the mixture from step (i). In non-productive step (ii), all components (except the sulfur-donating compound in this embodiment) are mixed under reactive machining conditions, where the conditions are high temperature, residence time, and shear in a machining apparatus such as an extruder, mesh mixer, or tangential mixer, and such conditions are sufficient to cause one or more of the following: That is, dispersion in a mixture of a rubbery polymer, a reinforcing filler covalently bonded to an organosilane coupling agent condensed after hydrolysis of step (i), a methylene donor, and a phloroglucinol resin; and / or reaction of the reinforcing filler covalently bonded to the organosilane coupling agent condensed after hydrolysis with the methylene donor and the phloroglucinol resin; and / or optionally, reaction of the methylene donor and the phloroglucinol resin to form a load-bearing path-reinforcing interpenetrating network dispersed within a primary network, thereby providing an uncured rubber composition.

[0091] If either the methylene donor or the phloroglucinol resin is not added in step (ii), the missing component may be added in the second non-productive mixing step (ii).

[0092] In productive step (iii), a sulfur-donating compound (f) is added to the mixture from step (ii).

[0093] Other components may be added to the rubber composition in any of steps (i), (ii), or (iii). Typical non-limiting examples of other components include activators, processing aids, accelerators, waxes, oils, ozone degradation inhibitors, and antioxidants.

[0094] Rubber compositions are typically mixed in mixing apparatuses under high shear conditions, where the mixture becomes self-generatingly hot as a result of the shearing and associated friction occurring primarily within the rubber mixture.

[0095] In a preferred embodiment of the present invention, the mixture of desired amounts of rubbery polymer, reinforcing filler, methylene donor, and organosilane coupling agent in step (i) is blended substantially uniformly under reactive machining conditions in a continuous or discontinuous mixing step (i). Discontinuous mixing can be used if excessive heating occurs and the rubber composition needs to be cooled. Cooling the rubber avoids or minimizes thermal decomposition of the rubbery polymer component or other components in the rubber composition. Preferably, the mixing step (i) is carried out at a temperature of 100°C to 200°C, more preferably 140°C to 180°C.

[0096] In step (iii), at least one sulfur-donating compound (f) can be mixed with the rubber composition from step (ii) together with other vulcanization accelerators. The mixing should be carried out under non-reactive machining conditions. As used herein, the expression “non-reactive machining” conditions should be understood to mean below ambient, ambient or slightly elevated temperature, residence time, and shear conditions within a machining apparatus such as an extruder, mesh mixer, tangential mixer, or roll mill, such conditions are sufficient to cause the dispersion of the sulfur-donating compound, e.g., vulcanizing agent and vulcanization accelerator into the rubber composition from step (ii) without causing substantial vulcanization of the rubber composition. Low temperature and low shear are advantageous when used in step (iii).

[0097] In step (iii), the residence time can be varied considerably and is generally chosen to allow for complete dispersion of the vulcanizing agent. In most cases, the residence time can be in the range of 0.5 to 30 minutes, preferably 5 to 20 minutes.

[0098] The temperature used in step (iii) can be in the range of 5°C to 150°C, preferably 30°C to 120°C, and more preferably 50°C to 110°C. These temperatures are lower than those used in reactive machining conditions to prevent or suppress premature curing of the sulfur-curable rubber, which may occur at higher temperatures, sometimes referred to as scorching of the rubber composition.

[0099] The rubber composition may be cooled to a temperature of 50°C or less, for example, during or after step (iii), or between step (i) and step (ii), or between step (ii) and step (iii).

[0100] In yet another embodiment of the present invention, when it is desired to mold and cure a rubber composition, the rubber composition is placed in a desired mold and heated at a temperature of at least about 130°C and below about 200°C for 1 to 60 minutes to cause vulcanization of the rubber.

[0101] A preferred rubber composition for forming a tire tread portion according to a preferred embodiment of the present invention comprises (a) a rubbery primary polymer or a blend of polymers, (b) reinforcing silica filler particles, (c) a methylene donor capable of forming a load-resistant path-reinforcing interpenetrating network that can be generated in situ, (d) an organosilane coupling agent that can react with the reinforcing filler and / or (e) a compound containing active hydrogen, i.e., at least one phloroglucinol resin, where components (b), (c), (d), and (e) contribute to the aforementioned load-resistant path-reinforcing interpenetrating network.

[0102] The rubber compositions of the present invention can be used for a variety of purposes. In one embodiment of the present invention, an article is provided in which at least one element is a cured rubber composition described herein. In another embodiment of the present invention, a tire is provided in which at least one element, for example, the tread, is a cured rubber composition described herein.

[0103] In yet another preferred embodiment, for example, the rubber composition can be used in the manufacture of articles such as shoe soles, hoses, seals, cable sheaths, gaskets, and other industrial products. Such articles can be made, shaped, molded and cured by various known and conventional methods obvious to those skilled in the art. In particular, the compositions and methods according to the present invention are particularly well suited for the manufacture of tires, especially truck or bus tires. [Examples]

[0104] To demonstrate the implementation of the present invention, the following examples were prepared and tested. However, these examples should not be considered to limit the scope of the present invention. The claims serve to define the present invention. The abbreviation PG stands for "phloroglucinol".

[0105] PG resin example 1. 440.0 g of phloroglucinol, 628.7 g of acetone, and 349.3 g of acid cation exchange catalyst (DIAION PK212LH, Mitsubishi Chemical Corporation) were placed in a flask and heated to 70°C. The reaction mixture was maintained at approximately 70°C for 24 hours. Next, 0.4 g of 25% sodium hydroxide solution was added. The solvent was then removed by vacuum distillation and the mixture was brought to 155°C. Once the temperature reached 155°C, the vacuum was released and the resin was discharged from the flask.

[0106] Table 1 lists the components used to prepare rubber compositions using natural rubber. The compositions contain silica coupled with bis[3-(triethoxysilyl)propyl]tetrasulfide (TESPT) or a mercaptosilane coupling agent, a methylene donor compound, and resorcinol or a resorcinol resin as controls. The compositions also contain a mercaptosilane coupling agent, a methylene donor compound, and a synthesized phloroglucinol resin. “Unproductive” combinations refer to combinations of materials that do not harden, while “productive” combinations are used to produce a resulting hardened composition. To illustrate current technology for truck and bus tire treads, compositions containing N121 carbon black are also prepared.

[0107] All four formulations (TESPT, mercaptosilane coupling agent, hexa(methoxymethyl)melamine with resorcinol or penacolite, and mercaptosilane coupling agent) Hexa(methoxymethyl)melamine was mixed with phloroglucinol resin in an internal rubber mixer using a mixing procedure that included three consecutive non-productive mixing steps followed by a final productive (curable) mix. The silica formulation containing TESPT was heat-treated at 145°C for 150 seconds during all three non-productive steps. Silica formulations containing a methylene donor compound with the resin were heat-treated at 155°C for 150 seconds during the first non-productive step, at 150°C for 150 seconds during the second non-productive step, and at 140°C for 150 seconds during the third non-productive step. Hexa(methoxymethyl)melamine and resorcinol, penacolite, or phloroglucinol resin for in-situ polymerization of load-bearing path-reinforcing interpenetrating networks were added in the second and third non-productive steps, respectively. The amount of PHR filler for hexa(methoxymethyl)melamine and resorcinol was used to determine the Shore A hardness of the cured compound. The hardness is the optimal value to ensure it falls within the typical range for truck tire compounding (Shore A hardness of 60-65) and to achieve the best balance of physical and dynamic properties. The rubber compositions shown in Table 1 were cured at 160°C for 15 minutes. The resulting dynamic and physical properties are shown in Tables 2 and 3 below, respectively. [Table 1] [Table 2] [Table 3]

[0108] Compounds containing a mercaptosilane coupling agent, a methylene donor compound, and resorcinol or resorcinol resin showed better wear and abrasion resistance compared to the TESPT compound, as measured using both a DIN abrader and an Angle Abrader (with a rotating grinding wheel as the grinding surface, under normal loads of 61N and 123N at both slip angles of 12° and 16°, respectively). However, unexpectedly and surprisingly, the compound containing the mercaptosilane coupling agent, methylene donor compound, and phloroglucinol resin showed much better rolling resistance characteristics (tanD, 60C) compared to the others, as measured using dynamic mechanical analysis, Metravib. In other words, this invention not only obtained an NR / silica tread system without resorcinol but also achieved an advance in improving low rolling resistance.

[0109] Unexpectedly, PG RESIN 1 performed well with rolling resistance that was 48% better than carbon black control, 30% better than penacolite, 13% better than resorcinol, and 17% better than TESPT, while maintaining the DIN wear of the PG RESIN Example 1 compound, which was 62% better than TESPT, 21% better than resorcinol, and comparable to penacolite.

[0110] PG resin example 2. 440.0 g of phloroglucinol, 628.7 g of acetone, and 349.3 g of acid cation exchange catalyst (DIAION PK212LH, Mitsubishi Chemical Corporation) were placed in a flask and heated to 70°C. The reaction mixture was maintained at approximately 70°C for 24 hours. Next, 0.4 g of 25% sodium hydroxide solution was added. The solvent was then removed by vacuum distillation and the mixture was brought to 155°C. When the temperature reached 155°C, the vacuum was released and the resin was discharged from the flask.

[0111] table 4The following lists the components used to prepare rubber compositions using natural rubber. The compositions contain silica coupled with a TESPT coupling agent, a methylene donor compound, and a phloroglucinol resin similar to that in the previous examples as controls. The compositions contain high and low amounts of the methylene donor compound, high and low amounts of TESPT, and high and low amounts of the synthesized phloroglucinol resin. "Unproductive" combinations refer to combinations of materials that do not cure, while "productive" combinations are used to produce cured compositions with low and high sulfur content.

[0112] All three formulations (normal sulfur, high sulfur, and low sulfur) were mixed in an internal rubber mixer using a mixing procedure that included three consecutive non-productive mixing steps followed by a final productive (curable) mix. All three formulations were subjected to the same process. This consisted of a first step of mixing at 65 rpm for 3 minutes to ensure incorporation, and then completing the additive distribution at 80 rpm for another 3 minutes. The mixing of the first masterbatch was completed with a silane treatment at 160°C for 2 minutes. In the second step, mixing was done at 140°C for 2 minutes, held at 140°C for 1.5 minutes, and then dumped. In the third mixing step, mixing was done at 40 rpm for 1.5 minutes, followed by holding the temperature at 100°C for 1 minute. The productive step involved mixing for 1.5 minutes and holding at 100°C for 1 minute. Similar physical properties were obtained by adjusting the phr values ​​of silane, HMMM, TESPT, resin, and sulfur. [Table 4] [Table 5] [Table 6] [Table 7] [Table 8]

[0113] All three experimental compounds exhibited equivalent physical properties. Without being constrained by theory, high sulfur content was offset by low levels of interpenetrating network monomers. Compounds with low sulfur content were offset by high levels of interpenetrating network components. Unexpectedly, the load-bearing path interpenetrating network can sufficiently offset the primary network over a wide range of additions.

[0114] As those skilled in the art will understand, hardness is a predictive factor for wear performance in DIN abrasion testing.

[0115] Various modifications and changes that do not depart from the scope and spirit of this invention will be apparent to those skilled in the art. This invention is not adequately limited to the embodiments described herein for illustrative purposes.

Claims

1. (a) Rubber-like polymers or blends of polymers; (b) at least one organosilane coupling agent; (c) at least one reinforcing filler that is reactive with the at least one organosilane coupling agent; (d) at least one methylene donor compound; (e) at least one phloroglucinol resin; and (f) at least one sulfur-donating compound A rubber composition containing the following:

2. The rubber composition according to Claim 1, wherein the rubbery polymer (a) is in the range of about 25 to about 95 weight percent based on the total weight of the rubber composition; the organosilane coupling agent (b) is in the range of 0.05 to 30 parts of organosilane coupling agent (b) per 100 parts of the rubbery polymer; the reinforcing filler (c) reactive with organosilane coupling agent (b) is in the range of 1 to 150 parts of reinforcing filler per 100 parts of the rubbery polymer; the methylene donor compound (d) is in the range of 0.1 to 30 parts of methylene donor compound per 100 parts of the rubbery polymer; the phloroglucinol resin (e) is in the range of 0.1 to 10 parts of phloroglucinol resin per 100 parts of the rubbery polymer; and the sulfur-donating compound (f) is in the range of 0.1 to 5 parts of sulfur-donating compound per 100 parts of the rubbery polymer.

3. The rubber composition according to claim 2, wherein the rubbery polymer (a) is selected from the group consisting of natural rubber (NR), synthetic polyisoprene (IR), polybutadiene (BR), various copolymers of butadiene, copolymer of isoprene, solution styrene-butadiene rubber (SSBR), emulsion styrene-butadiene rubber (ESBR), ethylene-propylene polymer (EPDM), acrylonitrile-butadiene rubber (NBR), and functionalized rubbers modified with at least one alkoxysilyl group, tin-containing group, amino group, hydroxyl group, carboxylic acid group, polysiloxane group, epoxy group, or phthalocyanino group.

4. The rubber composition according to claim 2, wherein the rubbery polymer (a) comprises natural rubber or a mixture of natural rubber and butadiene rubber.

5. The rubber composition according to claim 2, wherein the reinforcing filler (c) is selected from fibers, fine particles, or sheet-like structures containing a metalloid oxide or metal oxide having surface hydroxyl groups.

6. The rubber composition according to claim 5, wherein the reinforcing filler (c) contains settled silica.

7. The rubber composition according to claim 2, wherein the methylene donor compound (d) is selected from the group consisting of polyisocyanates, polyisocyanurates, epoxy resins, amino resins, and polyurethanes.

8. The amino resin is 1,1,3,3-tetra-methoxymethylurea, 1,3,3-tris-methoxymethylurea, 1,3-bis-methoxymethylurea, 1,1-bis-methoxymethylurea, 1,1,3,3-tetra-ethoxymethylurea, 1,3,3-tris-ethoxymethylurea, 1,3-bis-ethoxymethylurea, 1,1-bis-ethoxymethylurea, 1,1,3,3-tetra-propoxymethylurea, 1,3,3-tris-propoxymethylurea, 1,3-bis-propoxymethylurea, 1,1,3 ,3-tetra-butoxymethylurea, 1,1,3,3-tetra-phenoxymethylurea, N-(1,3,3-tris-ethoxymethylureidomethyl)-1,1,3,3-tetra-ethoxymethylurea, N,N'-bis-(1,1,3-tris-ethoxymethylureidomethyl)-1,3-bis-ethoxymethylurea, N,N'-bis-(1,1,3-tris-ethoxymethylureidomethoxymethyl)-1,3-bis-ethoxymethylurea, N,N,N',N',N'',N''-hexakis-methoxymethyl-[1,3,5]triazine-2,4 ,6-triamine,N,N,N′,N′,N″-pentakis-methoxymethyl-[1,3,5]triazine-2,4,6-triamine,N,N,N′,N″-tetrakis-methoxymethyl-[1,3,5]triazine-2,4,6-triamine,N,N,N′,N′,N″,N″-hexakis-ethoxymethyl-[1,3,5]triazine-2,4,6-triamine,N,N,N′,N′,N″-pentakis-ethoxymethyl-[1,3,5]triazine-2,4,6-triamine,N,N,N′,N″-tetrakis-ethoxymethyl-[1,3 [5] Triazine-2,4,6-triamine, N,N,N',N',N'',N''-Hexakis-propoxymethyl-[1,3,5] Triazine-2,4,6-triamine, N,N,N',N',N''-Pentakis-propoxymethyl-[1,3,5] Triazine-2,4,6-triamine, N,N,N',N''-Tetrakis-propoxymethyl-[1,3,5] Triazine-2,4,6-triamine, N,N,N',N',N'',N''-Hexakis-phenoxymethyl-[1,3,5] Triazine-2,4,6-triamine, N,N,N',N',The rubber composition according to claim 7, selected from the group consisting of N″-pentakis-phenoxymethyl-[1,3,5]triazine-2,4,6-triamine and N,N,N′,N″-tetrakis-phenoxymethyl-[1,3,5]triazine-2,4,6-triamine.

9. The phloroglucinol resin (e) is of formula (I): 【Chemistry 1】 The rubber composition according to claim 2, having the structure (wherein at least one of R1, R2, and R3 is bonded to a second phloroglucinol unit to form a disubstituted methylene bridge, the second of R1, R2, and R3 is a hydrogen atom or is bonded to a third phloroglucinol unit to form another disubstituted methylene bridge, the third of R1, R2, and R3 is a hydrogen atom).

10. The rubber composition according to claim 9, wherein the phloroglucinol resin is solid, and the phloroglucinol resin has the chemical structure according to claim 9, wherein the disubstituted methylene bridge formed is an isopropylidene bridge.

11. The rubber composition according to claim 9, wherein the phloroglucinol resin is solid, and the phloroglucinol resin has the chemical structure according to claim 9, wherein the disubstituted methylene bridge formed is a 2,2-disubstituted butane bridge.

12. The rubber composition according to claim 9, wherein the phloroglucinol resin is solid, and the phloroglucinol resin has the chemical structure according to claim 9, wherein the disubstituted methylene bridge formed is a 2,2-disubstituted 4-methylpentane bridge.

13. The rubber composition according to claim 2, wherein the solid phloroglucinol resin is a reaction product of phloroglucinol and ketone in the presence of an acid catalyst.

14. The rubber composition according to claim 12, wherein the ketone in the solid phloroglucinol resin according to claim 13 is selected from the group consisting of acetone, methyl ethyl ketone (MEK), and methyl isobutyl ketone (MIBK).

15. The rubber composition according to claim 2, wherein the sulfur-donating compound (f) is sulfur.

16. A method for preparing the rubber composition according to claim 2.

17. A cured rubber composition prepared from the rubber composition described in claim 2.

18. An article comprising the cured rubber composition according to claim 17.

19. The article according to claim 18, wherein the article is an element of a tire.

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