JP2013136746A - Tire with rubber component containing functionalized polybutadiene and functionalized styrene/butadiene elastomers - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide polybutadiene in a form of functionalized polybutadiene to be used in combination with a functionalized styrene/butadiene rubber.SOLUTION: A tire having a component of a rubber composition comprises: (A) from about 50 to about 80 phr of a solution polymerization prepared styrene/butadiene rubber, terminally di-functionalized at one terminal end of the styrene/butadiene rubber with alkoxysilane and either amine or thiol groups, wherein the styrene/butadiene rubber has a bound styrene content of: (1) from about 15 to 34 percent bound styrene units, or (2) from 35 to about 45 percent bound styrene units; and (B) from about 5 to about 70 phr of in-chain functionalized polybutadiene elastomer having a cis 1,4-isomeric content in a range of from about 30 to about 50 percent, a trans 1,4-isomeric content in a range of from about 40 to about 60 percent, which contains in-chain functionalization comprised of from about 0.2 to about 1.5 wt.% functional groups bound in the polybutadiene polymer chain, wherein the in-chain functionalized polybutadiene elastomer is comprised of a copolymer of in-chain repeat units derived from: (1) 1,3-butadiene monomer, and (2) a specified functionalized monomer.

Description

  A pneumatic rubber tire having a part comprising a silica reinforced rubber composition comprising a functionalized polybutadiene rubber and a functionalized styrene / butadiene rubber combination.

It is usually desirable for pneumatic rubber tires to contain various parts that have beneficial viscoelastic properties.
For example, in the case of a pneumatic rubber tire tread, the tread is a rubber composition that provides good wear resistance, wet traction (wet slip resistance) and acceptable rolling resistance properties for the tire itself. It is often desirable to be able to do so. The properties of such desirable rubber compositions for various tire parts depend primarily on the viscoelasticity of the elastomer or combination of elastomers.

  For example, to promote low rolling resistance of tire treads and to promote tread wear resistance, an elastomer having a relatively high elastic rebound characteristic value representing a relatively low energy loss during tire operation is a tire tread rubber composition. Has been used to provide.

  However, in order to promote wet traction (wet slip resistance) of the tire tread, an elastomer having a relatively low elastic rebound value representing a relatively high energy loss during tire operation is used in the tire tread rubber composition. .

  It has been recognized that it is often difficult to improve one such viscoelasticity without adversely affecting one or more other properties. Such difficulties and challenges are well known to those skilled in the art.

  In order to balance such viscoelastically contradictory properties, mixtures of various elastomers are usually used in tire tread rubber compositions. For example, a mixture of styrene / butadiene elastomer and polybutadiene elastomer is used in the tire tread rubber composition, and sometimes cis 1,4-polyisoprene rubber is added.

  To date, it has been proposed to provide tire treads as silica reinforcement-containing rubber compositions containing a combination of functionalized styrene / butadiene rubber and polybutadiene rubber (non-functionalized).

  Such styrene / butadiene rubbers are functionalized with a combination of alkoxysilane and thiol groups to promote enhanced silica reinforcement of the rubber composition. Thus, silica (eg, precipitated silica) is combined with the functionalized styrene / butadiene rubber by reaction of the functionalized styrene / butadiene rubber with the hydroxyl groups of the precipitated silica rather than (or in preference to) the polybutadiene rubber, such a manner. It is envisioned that preferential reinforcement, or at least greater reinforcement, will be provided over functionalized styrene / butadiene rubber rather than unfunctionalized polybutadiene rubber.

  In the present invention, by providing the polybutadiene used in combination with the functionalized styrene / butadiene rubber in the form of functionalized polybutadiene, the silica reinforcement of the polybutadiene component of the rubber composition is enhanced, thereby enhancing the rubber composition itself. We would like to evaluate the promotion of improved or improved silica reinforcement.

  The present invention has a moderate bound styrene content (e.g., about 15 to about 28 or 34 percent of styrene / butadiene rubber) to promote compatibility (miscibility) with the functionalized polybutadiene, and also functionalization It would also be desirable to provide functionalized styrene / butadiene that also has a high bound styrene content (eg, about 35 to about 45 percent of styrene / butadiene rubber) to promote incompatibility (immiscibility) with polybutadiene.

  In the description of the present invention, the term “phr”, when used, means “parts of material per 100 parts by weight rubber”. The terms “rubber” and “elastomer” may be used interchangeably unless otherwise specified. The terms “rubber composition”, “compound rubber” and “compound” are used interchangeably to refer to a rubber or elastomer blended or mixed with various ingredients and materials, unless otherwise specified. And such terms are well known to those skilled in the art.

  In the present invention, the term “functionalized” contains at least one functional group that reacts with a hydroxyl group (eg, a silanol group) contained on a precipitated silica reinforcement for a rubber composition. It relates to an elastomer.

SUMMARY OF THE INVENTION AND MODE FOR CARRYING OUT THE INVENTION

According to the present invention, based on parts by weight per hundred parts by weight of rubber (phr),
(A) about 50 to about 80 phr of solution polymerization prepared styrene / butadiene rubber (S-SBR) {one end of the styrene / butadiene rubber is a combination of alkoxysilane and either amine or thiol group, especially thiol group And (S-SBR) is
(1) about 15 to about 34, or about 18 to about 28 percent bound styrene units (S-SBR-A), or (2) about 35 to about 45 percent bound styrene units (S-SBR-B).
Having a bound styrene content of
(B) about 5 to about 70 phr of intrachain functionalized polybutadiene elastomer {cis 1,4-isomer content in the range of about 30 to about 50 percent, trans 1,4-isomer in the range of about 40 to about 60 percent Containing an intrachain functionalization having a body content and comprising from about 0.2 to about 1.5 weight percent functional groups attached to the polybutadiene polymer chain;
The intrachain functionalized polybutadiene elastomer is
(1) 1,3-butadiene monomer;
(2) Formula (I):

[Wherein R represents an alkyl group containing 1 to 10 carbon atoms or a hydrogen atom, R ¹ and R ² are the same or different, and both hydrogen atoms (provided that both R ¹ and R ² are hydrogen atoms) Not possible), or formula (II) or formula (III):

Wherein the R ³ groups are the same or different and contain 1 to 10 carbon atoms, alkyl groups, aryl groups, allyl groups and structural formula (IV):
_{(IV) - (CH 2)} y -O- (CH 2) z -CH 2
Wherein n, x, y and z represent an integer in the range of 1 to 10], wherein about 0.2 to about 0.2 to 1 of the 1,3-butadiene monomer A pneumatic rubber tire having a rubber composition part comprising a copolymer of intrachain repeat units derived from a functionalized monomer in an amount of about 1.5 weight percent.

In one embodiment, the rubber composition comprises about 40 to about 135, or about 50 to about 90 phr of (A) amorphous synthetic precipitated silica (precipitated silica), or (B) rubber reinforced carbon black, or (C) the precipitated silica. And rubber reinforced carbon black {the combination desirably includes (if desired) the precipitated silica and rubber reinforced carbon black in a weight ratio in the range of about 1/1 to about 10/1}
A reinforcing filler containing

  In one embodiment, the rubber composition comprises a moiety (eg, a siloxy moiety) that reacts with a hydroxyl group (eg, silanol group) on the precipitated silica and one of the elastomers (eg, carbon-carbon double bonds contained in the elastomer). And) a coupling agent for the precipitated silica having another part that interacts (for example, when the rubber composition contains the precipitated silica).

A representative example of a functionalized monomer represented by Structural Formula (I) is, for example, pyrrolidine ethylstyrene (PES).
A representative example of a functionalized monomer represented by Structural Formula (I) is, for example, vinyl benzyl pyrrolidine.

A representative example of a functionalized monomer represented by structural formula (I) is, for example, vinylbenzyldimethylamine.
Thus, in one embodiment, the intrachain functionalized polybutadiene may comprise repeating units derived from 1,3-butadiene and at least one of pyrrolidine ethylstyrene, vinyl benzyl dimethylamine, and vinyl benzyl pyrrolidine.

  In one embodiment, the polybutadiene copolymer further contains recurring units derived from isoprene. In that case, the isoprene monomer is copolymerized with the 1,3-butadiene and functionalized monomer. The isoprene repeating units comprise, for example, from about 2 to about 25, alternatively from about 2 to about 15 weight percent of the polybutadiene copolymer.

  For example, and in one embodiment, the functionalized polybutadiene rubber is a copolymer of 1,3-butadiene and a functionalized monomer in the presence of a polymerization initiator comprising n-butyllithium in a hydrocarbon solvent to initiate copolymerization. Below, it is produced by anionic copolymerization of 1,3-butadiene and a functional monomer. A polymerization regulator, such as but not limited to tetramethylethylenediamine (sometimes referred to as TMEDA), may be added to facilitate incorporation (distribution) of functional monomer units into the polybutadiene chain.

  In one embodiment, as previously indicated, the polybutadiene (prepared by the aforementioned n-butyllithium copolymerization initiator) has a cis 1,4-isomer content ranging from about 30 to about 50 percent, A trans 1,4-isomer content in the range of 40 to about 60 percent and a vinyl 1,2- content in the range of about 5 to about 20 percent can be included. Typical glass transition temperatures (Tg) range from about -85 ° C to about -95 ° C. Its number average molecular weight (Mn) can range, for example, from about 75,000 to about 350,000, and its weight average / number average (Mw / Mn) heterogeneity index is, for example, about It can range from 1 to about 2.5, alternatively from about 1.5 to about 2.5. See, for example, US Pat. No. 6,664,328.

  In one embodiment, at least one of the terminal difunctionalized styrene / butadiene elastomer and the intrachain functionalized polybutadiene elastomer is at least partially chain extended using tin tetrachloride or silicon tetrachloride, in particular tin tetrachloride. .

  For convenience, the polybutadiene rubber produced by n-butyllithium initiated polymerization is referred to herein as “lithium polybutadiene” and the functionalized polybutadiene rubber produced by n-butyllithium initiated copolymerization is referred to herein as “lithium polybutadiene copolymer”. I will call it.

  It is produced by solution polymerization of 1,3-butadiene in the presence of a nickel-based polymerization catalyst to form a polybutadiene elastomer from 1,3-butadiene monomer, and is at least 90 percent cis 1,4-isomer. In contrast to and instead of polybutadiene having a content and having a typical Tg in the range of about -100 ° C to about -110 ° C. Such nickel polybutadiene elastomers have, for example, a number average (Mn) in the range of about 230,000 to about 250,000, a heterogeneity index (Mw / Mn) in the range of about 1.5 to about 2. sell. See, for example, US Pat. No. 7,081,505.

  Functional styrene / butadiene rubbers are bifunctionalized together with a combination of alkoxysilanes and primary amino or thiol groups, especially thiol groups, at the same end of the styrene / butadiene elastomer. This is derived from a single bifunctional polymerization termination compound containing a combination of the alkoxysilane and a primary amino or thiol group.

  Thereby, a bifunctional combination of an alkoxysilyl group and a primary amino group or thiol group can be attached to one end of, for example, a styrene / butadiene rubber to form a terminal bifunctional styrene / butadiene rubber.

  Terminally difunctionalized styrene / butadiene rubber is obtained by polymerizing styrene and butadiene by anionic polymerization using, for example, an organic alkali metal and / or organic alkaline earth metal as an initiator in a hydrocarbon solvent. At that point, a terminator compound having an alkoxysilyl group and a primary amino group protected with a protecting group or a thiol group protected with a protecting group is added as a polymerization terminator to act on the living polymer chain end, and then For example by hydrolysis or deprotection of the protecting group by other suitable means. In one embodiment, the terminal bifunctional styrene / butadiene rubber can be made, for example, by the method shown in US Pat. No. 7,342,070. In another embodiment, the terminal bifunctional styrene-butadiene rubber can be produced by the method shown in, for example, WO 2007/047943.

  In one embodiment, as described in US Pat. No. 7,342,070, the terminal bifunctional styrene / butadiene rubber has the formula (V):

Wherein P is the (co) polymer chain of the styrene / butadiene copolymer, R ¹ is an alkylene group having 1 to 12 carbon atoms, and R ² and R ³ are 1 to 20 Each independently selected from an alkyl group having a carbon atom, an allyl group or an aryl group, R ² is preferably an ethyl group, n is a value of 1 or 2, and m is a value of 1 or 2, preferably 2. And k is a value of 1 or 2, and x is a value of 0 to 1, where n + m + k is an integer of 3 or 4.

  The terminator compound having a protected primary amino group and alkoxysilyl group may be any of a variety of compounds containing such groups known in the art. In one embodiment, the compound having a protected primary amino group and alkoxysilyl group may be, for example, N, N-bis (trimethylsilyl) aminopropylmethyldimethoxysilane, 1-trimethylsilyl-2,2-dimethoxy-1-aza -2-silacyclopentane, N, N-bis (trimethylsilyl) aminopropyltrimethoxysilane, N, N-bis (trimethylsilyl) aminopropyltriethoxysilane, N, N-bis (trimethylsilyl) aminopropylmethyldiethoxysilane, N, N-bis (trimethylsilyl) aminoethyltrimethoxysilane, N, N-bis (trimethylsilyl) -aminoethyltriethoxysilane, N, N-bis (trimethylsilyl) aminoethylmethyldimethoxysilane, N, N-bis (trimethylsilyl) ) Minoethylmethyldiethoxysilane and the like are preferred, but 1-trimethylsilyl-2,2-dimethoxy-1-aza-2-silacyclopentane, N, N-bis (trimethylsilyl) aminopropylmethyldimethoxysilane and N, N-bis (trimethylsilyl) aminopropylmethyldiethoxysilane. In one embodiment, the compound having a protected primary amino group and alkoxysilyl group is N, N-bis (trimethylsilyl) aminopropyltriethoxysilane.

For example, the styrene-butadiene rubber terminal-functionalized with an alkoxysilane group and a primary amine group can be, for example, HPR355 manufactured by Nippon Synthetic Rubber (JSR).
Furthermore, and in another embodiment, the solution polymerization prepared styrene-butadiene rubber can be terminally bifunctionalized with alkoxysilane groups and thiols. This is for example the living anionic styrene / butadiene polymer and the formula VI:
(VI) (R ⁴ O) _x R ⁴ _y Si—R ⁵ —S—SiR ⁴ ₃
[Wherein Si is silicon; S is sulfur; O is oxygen; x is an integer selected from 1, 2, and 3; y is an integer selected from 0, 1, and 2] X + y = 3; R ⁴ is the same or different and is (C ₁ -C ₁₆ ) alkyl; R ⁵ is aryl, and alkylaryl, or (C ₁ -C ₁₆ ) alkyl] Reaction product with silane-sulfide. In one aspect, R ⁵ is (C ₁ -C ₁₆ ) alkyl. In one embodiment, each R ⁴ group is the same or different and is each independently C ₁ -C ₅ alkyl and R ⁵ is C ₁ -C ₅ alkyl.

  As mentioned above, in one embodiment, the terminal bifunctional styrene / butadiene rubber is a polymerization terminated bifunctional containing a combination of alkoxysilane and primary amine or thiol group at one end of the styrene / butadiene elastomer. Depending on the compound, it is bifunctionalized with a combination of an alkoxysilane and a primary amine or thiol group.

  In such embodiments, for example, a styrene-butadiene rubber can be terminally bifunctionalized with alkoxysilane and thiol groups, such as an alkoxysilane / thiol functionalized SBR as described, for example, in Styron, WO 2007/047943. .

  In this (invention) evaluation, the purpose of including an intrachain functionalized polybutadiene rubber with a terminal difunctionalized styrene / butadiene rubber in place of the nonfunctionalized polybutadiene rubber is that the precipitated silica is only a terminal bifunctionalized styrene / butadiene elastomer. Rather than reacting with both functionalities of the intra-chain functionalized polybutadiene and the terminal bifunctional styrene / butadiene elastomer, and the precipitated silica is well dispersed in and throughout the intra-chain functionalized polybutadiene elastomer. It is to create a good dispersion of precipitated silica in the rubber composition itself. A further object is to promote greater and more complete dispersion of the precipitated silica particles throughout the intra-chain functionalized polybutadiene and terminally difunctionalized styrene / butadiene elastomer of the rubber composition, thereby increasing the rubber composition's greater. It is to promote wear resistance. This predicts good wear resistance of the rubber composition, and thus good tread wear resistance of a tire having such a rubber composition.

  Furthermore, the important aspects envisaged are miscibility (compatibility) and immiscibility of the functionalized elastomers to evaluate the use of terminally difunctionalized styrene / butadiene rubbers with high and low bond styrene content. (Incompatible) Creating and evaluating blends.

  For such purposes, a relatively immiscible rubber composition containing a combination of a terminal difunctionalized styrene / butadiene rubber and an intrachain functionalized polybutadiene rubber having a high bond styrene content is more suitable than that of the rubber composition. It is envisioned that the physical property of high resilience can also be beneficially promoted. This predicts a low internal heat generation of the rubber composition during operation, and thus a low temperature rise, and a good (low) rolling resistance of a tire having a tread of such a rubber composition.

  For such purposes, an immiscible blend of elastomers can be created by using terminally difunctionalized styrene / butadiene having a high bond styrene content and the wear resistance of the rubber composition, and thus such rubbers. It is also envisioned to enhance the good tread wear resistance of a tire having a tread of the composition.

  Also, in this evaluation, the purpose of providing a functionalized styrene / butadiene rubber (functionalized SBR) having a significantly lower bound styrene content, for example in the range of about 15 to about 30 or 34 percent of the rubber, was This is to promote the miscibility (compatibility).

  Low-bound styrene content terminal bifunctional styrene / butadiene rubber (functionalized SBR) used in combination with intrachain functionalized polybutadiene is a combination of the aforementioned end bifunctional styrene / butadiene and intrachain functionalized polybutadiene elastomers. Although expected to be less than an immiscible blend, it can beneficially facilitate the reduction of rolling resistance and tread wear resistance of tires having treads of such functionalized elastomer combinations.

  In practice, it is understood and preferred that the elastomers utilized in the rubber composition exclude polymers and copolymers of isobutylene (including its halogen-modified ones).

Examples of reinforced carbon blacks for elastomers can generally be found in The Vanderbilt Rubber Handbook , (1990), 13th edition, pages 416-419, together with their iodine number and DBP (dibutyl phthalate) absorption value.

  In the practice of the present invention, the use of the aforementioned silica and rubber reinforced carbon black reinforcing filler combination in a rubber composition may result in the combination of such silica and rubber reinforced carbon black reinforcing functionalized styrene / butadiene and functionalized polybutadiene. Provided to promote good rolling resistance (low rolling resistance) and tread wear resistance of tires having a tread of a rubber composition as contained with an elastomer combination.

Precipitated silica is, for example, as obtained by acidification of soluble silicates (eg sodium silicate or coprecipitation of silicate and aluminate).
The BET surface area of silica, measured using nitrogen gas, can range, for example, from about 50 to about 300, alternatively from about 120 to about 200 square meters / gram.

Silica may also have a dibutyl phthalate (DBP) absorption value in the range of, for example, about 100 to about 400, usually about 150 to about 300 cc / g.
A variety of commercially available silicas are contemplated for use in the present invention. For example, by way of example only and without limitation, silica commercially available from PPG Industries, Inc. under the trademark Hi-Sil, Standard 210, 243, etc .; Standard VN2 and VN3, silica available as 3770GR, silica available as Zeol 8745 from Huber, and the like.

When silica reinforcing agents are used in rubber tire treads, silica is conventionally used with coupling agents to help bond precipitated silica to diene elastomers.
Compounds that can react with both silica surfaces (eg hydroxyl groups on silica) and rubber elastomers (eg carbon-carbon double bonds in elastomers) in such a way that silica produces a reinforcing effect on the rubber, many of which are coupling agents Or commonly known to those skilled in the art as a coupler). Such coupling agents may be premixed or prereacted with, for example, silica particles, or may be added to the rubber mixture during rubber / silica processing or during the mixing stage. If the coupling agent and silica are added separately to the rubber mix during the rubber / silica mixing or during the processing stage, the coupling agent is then considered to bind in situ with the silica.

  In particular, such coupling agents include, for example, sulfur additives containing components or moieties that can react with the silica surface (silane moieties) and rubbers, particularly carbon-carbon double bonds or unsaturations. It can be composed of silanes having components or moieties that can also react with vulcanizable rubber. In this way, the coupler acts as a connecting bridge between silica and rubber, thereby enhancing the rubber reinforced side of the silica.

  In one aspect, the coupling agent silane apparently forms a bond to the silica surface, presumably through hydrolysis, and the rubber reactive component of the coupling agent binds to the carbon-carbon double bond contained in the rubber itself.

  A number of coupling agents are taught that are used to bond silica and rubber. For example, a silane coupling agent containing a polysulfide component or structure, such as an average of 2 to about 4 (eg, in the range of 2 to about 2.4 or in the range of 3 to about 4) linked sulfur atoms in the polysulfide bridge Bis- (3-alkoxysilylalkyl) polysulfide, such as bis- (3-triethoxysilylpropyl) polysulfide.

  A person skilled in the art will know that the rubber composition of the tread includes the reinforcing fillers such as carbon black and precipitated silica (in combination with a silica coupling agent) as defined herein, as well as an anti-degradation agent, Easy to be formulated with conventional formulation ingredients including process oils as defined in the description, stearic acid or zinc stearate, zinc oxide, sulfur contributors and vulcanization accelerators as defined herein You will understand.

  Such rubber formulations are well known to those skilled in the art. Deterioration inhibitors are typically of the amine or phenol type. Although stearic acid is usually cited as a rubber compounding component, the component itself is usually mainly stearic acid and oleic acid, linolenic acid and / or palmitic acid (as typically used, generally stearic acid It may be pointed out that it is obtained and used as a mixture of organic acids consisting of at least one of The mixture may also contain small amounts (less than about 6 weight percent) of myristic acid, arachidic acid and / or arachidonic acid. Such materials or mixtures are conventionally called stearic acid in the rubber compounding field.

  If such additives are used in normal or typical rubber loadings or ranges, they are not considered part of this invention unless otherwise. For example, some of the components can be classified as processing aids in one aspect. Such processing aids include, for example, waxes such as microcrystalline and paraffinic waxes typically used in the range of about 1 to 5 phr, often in the range of about 1 to about 3 phr; and typically Can be a resin (usually as a tackifier) used in the range of about 1 to 5 phr, often in the range of about 1 to about 3 phr, such as synthetic hydrocarbons and natural resins. Curing agents can be classified as a combination of sulfur and sulfur cure accelerators (usually simply referred to as accelerators) or sulfur donors / accelerators for rubber compounds. In the case of sulfur and accelerator hardeners, the amount of free sulfur added to the rubber composition in addition to the bis (3-triethoxysilylpropyl) polysulfide coupling agent that produces sulfur depends on the crosslink density of the cured rubber composition. In the range of about 1 to about 5 phr, more typically in the range of about 2 to about 4 phr; accelerators are often of the sulfenamide type, but for example about 0. It can be used in the range of 5 to about 5 phr, possibly in the range of about 1 to about 2 phr. Components containing elastomers, other than sulfur and accelerator hardeners, are usually first of all in at least one mixing stage, often a series of at least two sequential mixing stages (one mixing stage being used). Mixed together at a temperature in the range of about 130 ° C to about 140 ° C. Such a mixing stage is typically referred to as a non-productive mixing stage. Thereafter, sulfur and an accelerator, optionally one or more retarders and one or more anti-aging agents, are mixed with them to a temperature of about 90 ° C to about 120 ° C. This is typically referred to as a productive mixing stage. Such mixing procedures are well known to those skilled in the art.

  After mixing, the compounded rubber can be processed, for example, by extrusion through a suitable die and formed into a tire part such as a tire tread strip. The tire tread rubber strip is then typically built on a sulfur curable tire carcass and the assembly is subjected to elevated temperature and pressure conditions in a suitable mold by methods well known to those skilled in the art. , Molded and cured.

  The invention will be better understood by reference to the following examples. In the examples, parts and percentages are by weight unless otherwise indicated.

Example I
Manufactured and obtained miscible and immiscible blends of elastomers comprising terminal bifunctional styrene / butadiene elastomers containing about 23 percent and about 40 percent bound styrene, respectively, with polybutadiene and intrachain functionalized polybutadiene The physical properties of elastic rebound and wear resistance were evaluated.

  Two miscible blends of elastomers were made as Control Rubber Sample A and Experimental Rubber Sample B. For such blends, the terminal bifunctional styrene / butadiene elastomer contained about 23 percent bound styrene.

  Two immiscible blends of elastomers were also produced as control rubber sample C and experimental rubber sample D. For such blends, the terminal bifunctional styrene / butadiene elastomer contained about 40 percent bound styrene.

Various physical properties of the rubber composition were determined including elastic rebound characteristics at 23 ° C. and 100 ° C. and tan delta characteristics at −10 ° C. and Grosch abrasion rate.
The basic composition of the rubber composition is shown in Table 1 in units of parts by weight (phr) per 100 parts of rubber unless otherwise stated.

  The rubber compositions of rubber samples A and B can be used, for example, in the first non-productive mixing stage (NP-1) in an internal rubber mixer without adding sulfur and sulfur cure accelerators to the elastomer. It can be produced by mixing at a temperature of about 170 ° C. for about 4 minutes. The rubber mixture can then be mixed in a second non-productive mixing stage (NP-2) in a closed rubber mixer at a temperature of about 160 ° C. for about 4 minutes with additional ingredients. The rubber mixture can then be mixed in a third non-productive mixing stage (NP-3) in a closed rubber mixer at a temperature of about 150 ° C. for about 4 minutes without further addition of ingredients. The resulting rubber mixture can then be mixed in a productive mixing stage (PR) in a closed rubber mixer at a temperature of about 110 ° C. for about 2 minutes with the addition of sulfur and sulfur cure accelerator. The rubber composition can be sheeted out from each mixer during each non-productive mixing stage and prior to the productive mixing stage and cooled to below 50 ° C. For rubber samples C and D, a similar mixing procedure can be used, but only one non-productive mixing stage is utilized.

^{As a} monofunctionalized SBR, it has a bound styrene content of about 23 percent, such as Styron's SLR SE4602, and is functionalized with alkoxysilane and thiol groups and has a functionality of about −30 ° C. to about −10 ° C. Solution polymerization prepared styrene / butadiene rubber having a Tg in the range
^{As a} bifunctionalized SBR, it has a bound styrene content of about 40 percent, such as Styron's P6204M®, and is functionalized with alkoxysilane and thiol groups, ranging from about −30 ° C. to about −40 ° C. Styrene / Butadiene rubber prepared by solution polymerization having a Tg of
^{As a} trilithium polybutadiene, it is prepared by polymerizing 1,3-butadiene by n-butyllithium initiated polymerization and contains about 30 to about 50 percent cis 1,4-isomer units, about 40 to about 60 percent trans 1 A number average molecular weight (Mn) in the range of about 75,000 to about 350,000, having a microstructure comprising 1,4 isomer units and a vinyl 1,2-content of about 5 to about 20 percent. Polybutadiene having a heterogeneity index (Mw / Mn) in the range of 1 to about 2.5 and a Tg in the range of about -85 ° C to about -95 ° C.
^{A 4-} lithium polybutadiene copolymer prepared by n-butyllithium initiated copolymerization of 1,3-butadiene and pyrrolidine ethylstyrene (PES) in the presence of TMEDA, the copolymer being about 0.5 percent derived from pyrrolidine ethylstyrene. Intrachain Functionalized Polybutadiene Containing Repeating Units
Contains a combination of ⁵ fatty acids, mainly stearic acid, oleic acid and palmitic acid
⁶ Rhodia Zeosil 1165 MP (registered trademark)
50/50 (weight) composite of ⁷ carbon black and bis- (3-triethoxysilylpropyl) polysulfide (with an average range of about 2 to about 3 linked sulfur atoms in the polysulfide bridge), manufactured by Evonic Si266 (R), reported as a composite in the table
⁸ Sulfur cure accelerator as a combination of about 75/50 ratio of NN-dicyclohexyl-2-benzothiazolesulfenamide primary accelerator and (amine-containing) diphenylguanidine secondary accelerator
⁹ Combination of about 50/50 ratio of NN-dicyclohexyl-2-benzothiazole sulfenamide primary accelerator and zinc dibenzyldithiocarbamate secondary accelerator as sulfur cure accelerator. Thus, such sulfur curing components include sulfur, primary sulfur curing accelerators including NN-dicyclohexyl-2-benzothiazole sulfenamide, and secondary sulfur not including diphenylguanidine, including zinc dibenzyldithiocarbamate. Contains a curing accelerator. Accordingly, in one embodiment, the rubber composition contains a sulfur curing component including a sulfur curing accelerator excluding sulfur and diphenylguanidine.

  The rubber composition produced was optionally cured at a temperature of about 160 ° C. for about 14 minutes, and the resulting cured rubber samples were evaluated for various physical properties reported in Table 2 (here approximate numbers). Has been reported).

Miscible ^A elastomer (compatibility) is represented by tan delta versus temperature graph over the temperature range of about -110 ° C. ~ about + 60 ℃ blend of elastomer (temperature sweep tan delta value). The presence of a single significant peak in this temperature range indicates a miscible rubber blend, and the presence of a double significant peak (the double peak indicates the presence of each of the two elastomers individually) is immiscible. Indicates a rubber blend. Such indicators of rubber blend miscibility or immiscibility are recognized by those skilled in the art, and in Table 2, Yes is reported as elastomer miscibility and No is reported as elastomer immiscibility.

¹ rubber process analyzer equipment (eg rubber process analyzer RPA 2000)
² Rubber Sample ultimate tensile strength, ultimate elongation, Instron Corp. automatic test system equipment for measuring such Modulus
³ Grosch wear rate is performed on a LAT-100 wear tester and is measured in units of mg / kg of worn rubber. A test rubber sample is placed at a constant slip angle under a constant load (Newton) and traversed a predetermined distance on a rotating abrasive disc (disc is manufactured by HB Schleifmittel GmbH). Both lateral and circumferential frictional forces caused by a worn sample can be measured with a load (Newton) using a custom triaxial load cell. The surface temperature of the wear wheel is monitored during the test and reported as an average temperature. In practice, the low wear severity test may be performed, for example, at a load of 20 Newton, a slip angle of 2 degrees, a disk speed of 20 or 40 kph (km / hr), and a sample travel distance of 7,500 m. The medium wear severity test can be performed, for example, at a load of 40 Newton, a slip angle of 6 degrees, a disk speed of 20 kph, and a sample travel distance of 1,000 m. The high wear severity test can be performed, for example, at a load of 70 Newton, a slip angle of 12 degrees, a disk speed of 20 kph, and a sample travel distance of 250 m.

(A) For the miscible elastomer blends as control rubber sample A and experimental rubber sample B reported in Table 2, rubber samples A and B both have a terminal bifunctional styrene / butadiene elastomer with 23 percent bound styrene. Contained.

Control rubber sample A contained an unfunctionalized lithium polybutadiene elastomer.
Experimental rubber sample B contained an intrachain functionalized lithium polybutadiene copolymer.
From Table 2, the elastic rebound value (23 ° C.) of experimental rubber sample B with intrachain functionalized polybutadiene is 51.1 compared to the value of 40.2 for its control rubber sample A with unfunctionalized lithium polybutadiene. It can be seen that the value has increased significantly.

  From Table 2, it can be seen that the Grosch wear rate of rubber sample B containing intrachain functionalized polybutadiene is 145 mg / kg compared to the value of 154 mg / km for its control rubber sample A with unfunctionalized lithium polybutadiene. It can also be seen that it has decreased (improved).

  From Table 2, the tan delta value (−10 ° C.) of experimental rubber sample B with intrachain functionalized polybutadiene is 0.22 compared to the value of 0.27 for its control rubber sample A with unfunctionalized lithium polybutadiene. It can be seen that the value has decreased significantly.

  From the above, the presence of intrachain functionalized polybutadiene allows the precipitated silica to be more evenly distributed throughout the rubber composition, instead of concentrating mainly on the low-bond styrene-containing terminal bifunctional styrene / butadiene portion of the rubber composition. It is concluded that this is possible. This brings about the following.

(1) Beneficially improved (increased) elastic rebound value (23 ° C.), which shows a beneficial decrease in hysteresis, which is expected to reduce the internal heat generation of tire components when using tires, and A beneficial reduction in rolling resistance of tires having such rubber composition parts (eg treads) is expected;
(2) Beneficially improved (reduced) Grosch wear rate, which predicts increased tread wear resistance of tires having such rubber composition treads; and (3) Similar Tan Delta (-10 C) value, which indicates that the wet traction of a tire tread of such a composition would be similar.

(B) For the immiscible elastomer blends as control rubber sample C and experimental rubber sample D reported in Table 2, rubber samples C and D are both terminal bifunctional styrene / butadiene elastomers having 40 percent bound styrene. Contained.

Control rubber sample C contained an unfunctionalized lithium polybutadiene elastomer.
Experimental rubber sample D contained an intrachain functionalized lithium polybutadiene copolymer.
From Table 2, the elastic rebound value (23 ° C.) of experimental rubber sample D with intrachain functionalized polybutadiene is 47.2 compared to the value of 36.2 for its control rubber sample C with unfunctionalized lithium polybutadiene. It can be seen that the value significantly increased.

  From Table 2, it can be seen that the Grosch wear rate for rubber sample D containing intra-chain functionalized polybutadiene is 109 mg / kg compared to 123 mg / km for its control rubber sample C with unfunctionalized lithium polybutadiene. It can also be seen that it has been significantly reduced (improved).

  From Table 2, the tan delta value (−10 ° C.) of experimental rubber sample D with intrachain functionalized polybutadiene is approximately 0.38, which is approximately 0.37 of its control rubber sample A with unfunctionalized lithium polybutadiene. You can see that it was the same.

  From the above, the presence of intrachain functionalized polybutadiene allows the precipitated silica to disperse more uniformly throughout the rubber composition, instead of concentrating mainly on the high bond styrene-containing terminal bifunctional styrene / butadiene portion of the rubber composition. It is concluded that this is possible. This brings about the following.

(A) Remarkably beneficially improved (increased) elastic rebound value (23 ° C.), which shows a significantly beneficial reduction in hysteresis, and is expected to reduce the internal heat generation of tire components when using tires A beneficial reduction in rolling resistance of tires having such rubber composition parts (eg treads) is expected;
(B) a significantly beneficially improved (reduced) Grosch wear rate, which predicts significantly increased tread wear resistance of tires having such rubber composition treads; and (C) similar tan delta ( −10 ° C.) value, which indicates that the wet traction of a tire tread of such a composition will be substantially maintained.

Example II
An automobile tire of tire size P225 / 60R16 having a tread comprising the rubber composition represented by samples A, B, C and D of Example I is manufactured, tire rolling resistance, tread wear and tread traction (stop distance). Were tested. The results are shown in Table 3 below.

  Tires A and B used treads containing miscible blends of elastomers (samples) A and B, respectively. These included a miscible blend of terminally bifunctionalized SBR containing about 23 percent bound styrene with in-chain functionalized polybutadiene for experimental tire B and unfunctionalized polybutadiene for control tire A.

  Tires C and D used treads containing immiscible blends of elastomers (samples) C and D, respectively. These included an immiscible blend of terminally bifunctionalized SBR containing about 40 percent bound styrene with intrachain functionalized polybutadiene for experimental tire D and unfunctionalized polybutadiene for control tire C.

  From Table 3, both the rolling resistance value and the tread wear value, in the case of tires (treads) B and D, are the addition of intrachain functionalized polybutadiene to the terminal bifunctionalized styrene / butadiene rubber of the silica reinforcing agent-containing rubber composition. Compared to their individually related comparative tires A and C, which do not contain intrachain functionalized polybutadiene rubber, have been significantly and beneficially improved without significantly affecting their wet traction. I understand.

  When comparing the use of non-miscible and miscible blends of functionalized polybutadiene and functionalized styrene / butadiene rubber in a silica reinforcing agent-containing rubber composition for tire treads, the following is observed.

  (A) For tire D having a tread comprising an immiscible blend of an intrachain functionalized polybutadiene and a terminal bifunctionalized styrene / butadiene (B) containing 40 percent bound styrene, particularly tire rolling resistance and resistance A significant performance benefit is observed with respect to tread wear.

  (B) In the case of tire B having a tread comprising a miscible blend of an end chain functionalized polybutadiene and a terminally difunctionalized styrene / butadiene (A) containing 23 percent bound styrene, especially tire rolling resistance and tread resistance In terms of wear, a beneficial increase is observed in the performance of the tire, but not a significant benefit.

  While certain representative embodiments and details have been set forth for the purpose of illustrating the present invention, various changes and modifications may be made therein by those skilled in the art without departing from the spirit or scope of the invention. It will be clear.

[Aspect of the Invention]
1. A pneumatic rubber tire based on 100 parts by weight of rubber per part (phr),
(A) about 50 to about 80 phr of solution polymerization prepared styrene / butadiene rubber (S-SBR) {one end of the styrene / butadiene rubber is terminal bifunctionalized with a combination of alkoxysilane and either amine or thiol group (S-SBR) is
(1) having a bound styrene content of about 15 to about 34 percent bound styrene units, or (2) 35 to about 45 percent bound styrene units};
(B) about 5 to about 70 phr of intrachain functionalized polybutadiene elastomer {cis 1,4-isomer content in the range of about 30 to about 50 percent, trans 1,4-isomer in the range of about 40 to about 60 percent Containing an intrachain functionalization having a body content and comprising from about 0.2 to about 1.5 weight percent functional groups attached to the polybutadiene polymer chain;
The intrachain functionalized polybutadiene elastomer is
(1) 1,3-butadiene monomer;
(2) Formula (I):

[Wherein R represents an alkyl group containing 1 to 10 carbon atoms or a hydrogen atom, R ¹ and R ² are the same or different, and both hydrogen atoms (provided that both R ¹ and R ² are hydrogen atoms) Not possible), or formula (II) or formula (III):

Wherein the R ³ groups are the same or different and contain 1 to 10 carbon atoms, alkyl groups, aryl groups, allyl groups and structural formula (IV):
_{(IV) - (CH 2)} y -O- (CH 2) z -CH 2
Wherein n, x, y and z represent an integer in the range of 1 to 10], wherein about 0.2 to about 0.2 to 1 of the 1,3-butadiene monomer And a rubber composition part comprising a copolymer of intrachain repeat units derived from a functionalized monomer in an amount of about 1.5 weight percent.

2. The rubber composition comprises about 40 to about 135 phr of (A) amorphous synthetic precipitated silica (precipitated silica), or (B) rubber reinforced carbon black, or (C) a combination of the precipitated silica and rubber reinforced carbon black. The tire according to 1, which contains a reinforcing filler.

3. The tire of claim 2, wherein the reinforcing filler comprises precipitated silica and rubber reinforced carbon black in a weight ratio ranging from about 1/1 to about 10/1.
4). The tire of claim 1, wherein the rubber composition contains a coupling agent for the precipitated silica having a portion that reacts with hydroxyl groups on the precipitated silica and another portion that interacts with one of the elastomers.

5. 2. The tire according to 1, wherein the functionalized monomer represented by the structural formula (I) is pyrrolidine ethylstyrene.
6). 2. The tire according to 1, wherein the functionalized monomer represented by the structural formula (I) is vinylbenzylpyrrolidine.

7). The tire according to 1, wherein the functionalized monomer represented by the structural formula (I) is vinylbenzyldimethylamine.
8). The tire of claim 1, wherein the intrachain functionalized polybutadiene comprises repeating units derived from 1,3-butadiene and at least one of pyrrolidine ethylstyrene, vinylbenzyldimethylamine, and vinylbenzylpyrrolidine.

9. The tire of claim 1, wherein the intrachain functionalized polybutadiene copolymer further comprises from about 2 to about 25 percent of repeating units derived from isoprene.
10. The intrachain functionalized polybutadiene rubber is produced by anionic copolymerization of 1,3-butadiene and a functional monomer in a hydrocarbon solvent in the presence of a polymerization initiator containing n-butyllithium to initiate copolymerization. A tire according to claim 1, wherein a copolymerization modifier comprising tetramethylethylenediamine is added to promote the incorporation of the functional monomer unit into the polybutadiene chain.

  11. The tire of claim 1, wherein the terminal bifunctional styrene / butadiene elastomer is a styrene / butadiene elastomer containing terminal functionalization comprising a combination of alkoxysilane and primary amino groups.

  12 The tire of claim 1, wherein the terminal bifunctional styrene / butadiene elastomer is a styrene / butadiene elastomer containing terminal functionalization comprising a combination of alkoxysilane and thiol groups.

13. The tire of claim 1, wherein the terminal bifunctional styrene / butadiene elastomer is at least partially chain extended using tin tetrachloride or silicon tetrachloride.
14 The tire of claim 1, wherein the intrachain functionalized polybutadiene elastomer is at least partially chain extended using tin tetrachloride or silicon tetrachloride.

  15. The terminal bifunctional styrene / butadiene rubber has the formula (V):

[Wherein P is a copolymer chain of a styrene / butadiene copolymer, R ¹ is an alkylene group having 1 to 12 carbon atoms, and R ² and R ³ are 1 to 20 carbon atoms. Each independently selected from an alkyl group, an allyl group, or an aryl group, R ² is preferably an ethyl group, n is a value of 1 or 2, m is a value of 1 or 2, and preferably 2. k is a value of 1 or 2, x is a value of 0 to 1, provided that n + m + k is an integer of 3 or 4.

16. The terminal difunctionalized styrene / butadiene rubber is a living anionic styrene / butadiene polymer and has the formula VI:
(VI) (R ⁴ O) _x R ⁴ _y Si—R ⁵ —S—SiR ⁴ ₃
[Wherein Si is silicon; S is sulfur; O is oxygen; x is an integer selected from 1, 2, and 3; y is an integer selected from 0, 1, and 2] X + y = 3; R ⁴ is the same or different and is (C ₁ -C ₁₆ ) alkyl; R ⁵ is aryl, and alkylaryl, or (C ₁ -C ₁₆ ) alkyl] The tire according to 1, wherein the reaction product with silane-sulfide is terminally bifunctionalized with an alkoxysilane group and a thiol. In one aspect, R ⁵ is (C ₁ -C ₁₆ ) alkyl. In one embodiment, each R ⁴ group is the same or different and is each independently C ₁ -C ₅ alkyl and R ⁵ is C ₁ -C ₅ alkyl.

17. The tire of claim 1, wherein the terminal bifunctional styrene / butadiene elastomer contains about 18 to about 28 percent bound styrene units.
18. The tire of claim 1, wherein the terminal bifunctional styrene / butadiene elastomer contains from about 35 to about 45 percent bound styrene units.

  19. The rubber composition includes a sulfur, a primary sulfur curing accelerator including NN-dicyclohexyl-2-benzothiazolesulfenamide, and a secondary sulfur curing accelerator including zinc dibenzyldithiocarbamate and not diphenylguanidine. 2. The tire according to 1, which contains a sulfur curing component.

  20. The tire according to 1, wherein the rubber composition contains a sulfur curing component including a sulfur curing accelerator excluding sulfur and diphenylguanidine.

Claims (20)

A pneumatic rubber tire based on 100 parts by weight of rubber per part (phr),
(A) 50-80 phr solution polymerization prepared styrene / butadiene rubber (S-SBR) {One end of the styrene / butadiene rubber is end-bifunctionalized with a combination of alkoxysilane and either amine or thiol group. And (S-SBR) is
(1) having a bound styrene content of 15 to 34 percent bound styrene units, or (2) 35 to 45 percent bound styrene units};
(B) 5-70 phr intrachain functionalized polybutadiene elastomer {having cis 1,4-isomer content in the range of 30-50 percent, trans 1,4-isomer content in the range of 40-60 percent Containing an intrachain functionalization containing 0.2 to 1.5 weight percent functional groups attached to the polybutadiene polymer chain;
Here, the intrachain functionalized polybutadiene elastomer is
(1) 1,3-butadiene monomer;
(2) Formula (I):

[Wherein R represents an alkyl group containing 1 to 10 carbon atoms or a hydrogen atom, R ¹ and R ² are the same or different, and both hydrogen atoms (provided that both R ¹ and R ² are hydrogen atoms) Not possible), or formula (II) or formula (III):

Wherein the R ³ groups are the same or different and contain 1 to 10 carbon atoms, alkyl groups, aryl groups, allyl groups and structural formula (IV):
_{(IV) - (CH 2)} y -O- (CH 2) z -CH 2
Wherein n, x, y, and z represent an integer in the range of 1 to 10, and have a structural formula of 0.2 to 1 of the 1,3-butadiene monomer. A tire having a rubber composition part, comprising: a copolymer of intrachain repeat units derived from a functional monomer in an amount of 5 weight percent. The rubber composition contains 40 to 135 phr of (A) amorphous synthetic precipitated silica (precipitated silica), or (B) rubber-reinforced carbon black, or (C) a combination of the precipitated silica and rubber-reinforced carbon black. The tire according to claim 1, further comprising an agent. The tire according to claim 2, characterized in that the reinforcing filler comprises precipitated silica and rubber reinforced carbon black in a weight ratio in the range of 1/1 to 10/1. The rubber composition contains a coupling agent for the precipitated silica having a portion that reacts with hydroxyl groups on the precipitated silica and another portion that interacts with one of the elastomers. The tire according to 1. The tire according to claim 1, characterized in that the functionalized monomer represented by Structural Formula (I) is pyrrolidine ethylstyrene. The tire according to claim 1, characterized in that the functionalized monomer represented by the structural formula (I) is vinylbenzylpyrrolidine. The tire according to claim 1, characterized in that the functionalized monomer represented by Structural Formula (I) is vinylbenzyldimethylamine. 2. The intrachain functionalized polybutadiene comprises repeating units derived from 1,3-butadiene and at least one of pyrrolidine ethylstyrene, vinyl benzyl dimethylamine and vinyl benzyl pyrrolidine. Tires. The tire of claim 1, wherein the intrachain functionalized polybutadiene copolymer further comprises 2 to 25 percent of repeating units derived from isoprene. The intrachain functionalized polybutadiene rubber is produced by anionic copolymerization of 1,3-butadiene and a functional monomer in a hydrocarbon solvent in the presence of a polymerization initiator containing n-butyllithium to initiate copolymerization. A copolymer of 1,3-butadiene and a functionalized monomer, wherein a polymerization regulator comprising tetramethylethylenediamine is added to promote incorporation of the functional monomer unit into the polybutadiene chain. The tire according to 1. The tire of claim 1, wherein the terminal bifunctional styrene / butadiene elastomer is a styrene / butadiene elastomer containing terminal functionalization comprising a combination of alkoxysilanes and primary amino groups. The tire of claim 1, wherein the terminal bifunctional styrene / butadiene elastomer is a styrene / butadiene elastomer containing terminal functionalization comprising a combination of alkoxysilane and thiol groups. The tire according to claim 1, characterized in that the terminally difunctionalized styrene / butadiene elastomer is at least partially chain extended using tin tetrachloride or silicon tetrachloride. The tire according to claim 1, characterized in that the intrachain functionalized polybutadiene elastomer is at least partially chain extended using tin tetrachloride or silicon tetrachloride. The terminal bifunctional styrene / butadiene rubber has the formula (V):

[Wherein P is a copolymer chain of a styrene / butadiene copolymer, R ¹ is an alkylene group having 1 to 12 carbon atoms, and R ² and R ³ are 1 to 20 carbon atoms. Each independently selected from an alkyl group, an allyl group, or an aryl group, R ² is preferably an ethyl group, n is a value of 1 or 2, m is a value of 1 or 2, and preferably 2. 2. The tire according to claim 1, wherein k is a value of 1 or 2, and x is a value of 0 to 1, where n + m + k is an integer of 3 or 4. The terminal difunctionalized styrene / butadiene rubber is a living anionic styrene / butadiene polymer and has the formula VI:
(VI) (R ⁴ O) _x R ⁴ _y Si—R ⁵ —S—SiR ⁴ ₃
[Wherein Si is silicon; S is sulfur; O is oxygen; x is an integer selected from 1, 2, and 3; y is an integer selected from 0, 1, and 2] X + y = 3; R ⁴ is the same or different and is (C ₁ -C ₁₆ ) alkyl, preferably C ₁ -C ₅ alkyl; R ⁵ is aryl, alkylaryl or (C ₁ -C ₁₆ ); Alkyl, preferably C ₁ -C ₅ alkyl; particularly preferably each R ⁴ group is the same or different and is each independently C ₁ -C ₅ alkyl, and R ⁵ is C ₁ -C ₅ alkyl] Characterized by being terminally bifunctionalized with an alkoxysilane group and a thiol as a reaction product with a silane-sulfide represented by The tire of claim 1, wherein the terminal bifunctional styrene / butadiene elastomer contains 18 to 28 percent bound styrene units. The tire of claim 1, wherein the terminal bifunctional styrene / butadiene elastomer contains 35 to 45 percent bound styrene units. The rubber composition includes a sulfur, a primary sulfur curing accelerator including NN-dicyclohexyl-2-benzothiazolesulfenamide, and a secondary sulfur curing accelerator including zinc dibenzyldithiocarbamate and not diphenylguanidine. The tire according to claim 1, further comprising a sulfur curing component. The tire according to claim 1, wherein the rubber composition contains a sulfur curing component including a sulfur curing accelerator excluding sulfur and diphenylguanidine.