CN116903944A

CN116903944A - Rubber composition and tire

Info

Publication number: CN116903944A
Application number: CN202310381044.2A
Authority: CN
Inventors: E·恩格尔丁格; M·韦德特
Original assignee: Goodyear Tire and Rubber Co
Current assignee: Goodyear Tire and Rubber Co
Priority date: 2022-04-12
Filing date: 2023-04-11
Publication date: 2023-10-20
Also published as: JP2023156265A; BR102023006712A2

Abstract

The invention discloses a rubber composition and a tire. Disclosed is a sulfur-vulcanizable elastomeric composition comprising from 50phr to 100phr of at least one partially saturated elastomer comprising repeat units, wherein up to 15% of all repeat units of the partially saturated elastomer comprise double bonds; from 0phr to 50phr of at least one diene-based elastomer; and 40phr to 200phr of at least one filler, wherein the filler comprises predominantly silanized silica or pre-silanized silica. The elastomeric composition may be used in a tire component such as a tire tread.

Description

Rubber composition and tire

Technical Field

The present invention relates to a sulfur-vulcanizable or vulcanized elastomeric composition, particularly for rubber components, such as tires. Furthermore, the present invention relates to a tire rubber component or tire comprising such an elastomeric composition.

Background

In view of the continuing need for improved tire performance, tire manufacturers continually evaluate and test new material combinations. In particular, in many tire tread elastomeric compositions, it is difficult to break the hysteresis/tear tradeoff. While good pull-up and/or tear properties and maintaining the rolling resistance index at a high level may be achieved in some methods, it has been found difficult to achieve the desired stiffness properties at the same time. Accordingly, there is a need to provide new elastomeric compositions for tires that provide good stiffness, tear and rolling resistance properties.

Disclosure of Invention

The present invention relates to an elastomeric composition according to claim 1, and a tyre according to claim 10.

The dependent claims relate to preferred embodiments of the invention.

It is a first object of the present invention to provide an elastomeric composition having desirable rolling resistance and/or hysteresis properties.

It is another object of the present invention to provide an elastomeric composition having good tensile properties.

It is another object of the present invention to provide an elastomeric composition having sufficient or advanced stiffness.

It is a further object of the present invention to provide an elastomeric composition which exhibits a good balance of hysteresis properties, tensile properties and compound stiffness.

Detailed description of the preferred embodiments

In a first aspect thereof, the present invention relates to a sulfur-vulcanizable (or vulcanized) elastomeric composition (in other words a rubber composition) comprising from 50phr to 100phr of at least one partially saturated elastomer comprising repeating units, wherein up to 15% of all repeating units of the partially saturated elastomer comprise double bonds. Furthermore, the elastomeric composition comprises from 0phr to 50phr of at least one diene-based elastomer and from 40phr to 200phr of at least one filler, wherein the filler comprises predominantly silanized silica, preferably pre-silanized silica. In other words, the majority (by weight) of the filler is silanized or pre-silanized silica.

Surprisingly, the inventors have found that the combination of a partially unsaturated elastomer having a limited number of double bonds with silanized or pre-silanized silica results in an unexpected increase in the stiffness of the compound. In general, when such silica is used in combination with conventional elastomers, the opposite is observed, resulting in limited stiffness. However, in combination with unsaturated polymers having a limited number of double bonds, the inventors have found an unexpectedly opposite effect.

In a preferred embodiment, the partially saturated elastomer has a glass transition temperature of from-20 ℃ to-65 ℃. Such Tg ranges are suitable, for example, for polymer applications in rubber compositions for passenger car and truck tread applications.

In another preferred embodiment, the partially saturated elastomer has a weight average molecular weight Mw of 150,000g/mol to 900,000g/mol, preferably 200,000g/mol to 500,000 g/mol. Mw is determined by Gel Permeation Chromatography (GPC) according to ASTM 5296-11 using polystyrene calibration standards or equivalents. This molecular weight range helps to achieve a proper balance between processability and hysteresis properties.

In another preferred embodiment, the partially saturated elastomer has a glass transition temperature of from-20 ℃ to-45 ℃, preferably from-25 ℃ to-40 ℃.

In another preferred embodiment, the partially saturated elastomer has a glass transition temperature of from-45 ℃ to-65 ℃, preferably from-45 ℃ to-60 ℃.

In another preferred embodiment, at most 11%, preferably at most 8% of all repeating units have double bonds and/or at least 4% of the repeating units have double bonds. In particular, it may be less desirable for the elastomer to be completely free of double bonds or to be completely hydrogenated. In particular, some of the double bonds (typically those derived from monomer units) should remain in situ for crosslinking purposes, or in other words, for sulfur vulcanization purposes. When calculating double bonds herein, bonds in aromatic structures or groups, such as bonds of styrene repeat units, are not calculated as double bonds. However, styrene units are still calculated as repeating units for determining the total number of repeating units in the polymer or elastomer.

In another preferred embodiment, the partially saturated elastomer comprises repeating units formed from residues of monomers selected from the group consisting of ethylene, propylene, butadiene, isoprene and styrene. These monomers are preferably used to prepare or obtain partially saturated elastomers. One or more of the residues may be hydrogenated. In other words, the double bonds of one or more of the residues may be hydrogenated.

In another preferred embodiment, the partially saturated elastomer is a hydrogenated styrene-butadiene rubber, preferably a hydrogenated solution polymerized styrene-butadiene rubber (SSBR). Hydrogenated SSBR and its preparation are known per se to the person skilled in the art and are described, for example, in U.S. patent application publications US 2018201065A1, US 2018251576A1 and US 20190062539 A1.

In yet another preferred embodiment, the partially saturated elastomer is a styrene-butadiene rubber, such as a partially saturated solution polymerized styrene butadiene rubber, having one or more of the following:

i) Less than 5% of unhydrogenated vinyl groups based on the total number of vinyl groups of the hydrogenated styrene butadiene rubber;

ii) less than 20%, preferably less than 10%, or preferably less than 5% of the unhydrogenated double bonds in the cis-1, 4 and trans-1, 4 butadiene repeat units, based on the total number of cis-1, 4 and trans-1, 4 butadiene repeat units;

iii) 80% (preferably 85% or 90%) to 99%, or 90% to 98% of hydrogenated double bonds; and

iv) a bound styrene content of 5% to 40%, preferably 20% to 35%, and a butadiene content of 50% to 95%, or 50% to 80% by weight.

In another preferred embodiment, the hydrogenated styrene-butadiene rubber has from 90% to 98% hydrogenated double bonds. In other words, double bonds which are not hydrogenated remain. The number of double bonds can be determined by NMR, as known to those skilled in the art. This also applies to partially saturated elastomers which are not styrene-butadiene rubbers.

In yet another preferred embodiment, the styrene-butadiene rubber will have a bound styrene content of from 10% to 40% and its bound butadiene content will be from 60% to 90% by weight as determined by NMR. Styrene-butadiene rubber will typically have a bound styrene content of 20% to 35% and a bound butadiene content of 65% to 80%.

In another preferred embodiment, the BET surface area of the silica is less than 150g/m ² Preferably less than 120g/m ² Even more preferably up to 100g/m ² 。

In another preferred embodiment, the BET surface area of the silica is 50g/m ² To 100g/m ² . The low surface area may here help to provide better silica dispersion, which helps to obtain low hysteresis.

Such BET surface areas are herein measured by nitrogen adsorption according to ASTM D6556 or equivalent. The BET method of measuring surface area is also described, for example, in Journal ofthe American Chemical Society, volume 60.

In a further preferred embodiment, the silanized or pre-silanized (and preferably precipitated) silica has a length of 130m ² /g to 210m ² /g, optionally 130m ² /g to 150m ² CTAB adsorption surface area per gram. The CTAB (cetyltrimethylammonium bromide) method of determining the surface area of silica according to ASTM D6845 is known to those skilled in the art.

In another preferred embodiment, the silanized or pre-silanized (and optionally precipitated) silica used is hydrophobized by treatment with at least one silane prior to its addition to the elastomeric composition. Suitable silanes include, but are not limited to, alkylsilanes, alkoxysilanes, organoalkoxysilyl polysulfides, and organomercaptoalkoxysilanes.

In another preferred embodiment, the pre-silanized silica is silica pre-reacted with a sulfur-containing silane.

In another preferred embodiment, rather than reacting the silica with the silica coupling agent in situ within the elastomeric composition, the pre-silanized silica may be pre-treated with a silica coupling agent comprising, for example, an alkoxy organomercaptoalkoxysilane or a combination of an alkoxysilane and an organomercaptoalkoxysilane prior to blending the pre-silanized silica with the elastomer. See, for example, U.S. patent 7,214,731, which shows further details of preparing such pre-silanized silica.

In another preferred embodiment, the silanized or pre-silanized silica is a (optionally precipitated) silica pre-reacted with a silica coupling agent comprising bis (3-triethoxysilylpropyl) polysulfide or an alkoxyorganomercaptosilane containing an average of 1-5, preferably 2-4, linked sulfur atoms in its polysulfide bridge. The silane improves compatibility with the rubber material, dispersion or rubber matrix and/or supports the curing process.

The amount of mercapto groups on the silica surface may be 0.1 to 1 wt%, or 0.4 to 0.6 wt%, where 100% is the (total) weight of the silica sample. Such an assay of sulfhydryl groups is performed by titration.

In addition to the mercapto groups coupled with the silica, the silica may contain a compatibilizer, which is typically a hydrocarbon chain/carbon chain material having multiple carbon atoms (e.g., at least 4 carbon atoms) along its chain. Such compatibilizers may facilitate the mixing of the compositions. In one example, the weight percent of carbon surface loading/functionalization is from 2 to 10, or alternatively from 3 to 8. Also, 100% is herein the total weight of the silica sample.

The silanized or pre-silanized silica may optionally be treated with a silica dispersing aid. Such silica dispersing aids may comprise glycols, such as fatty acids, diethylene glycol, polyethylene glycol, hydrogenated or non-hydrogenated C ₅ Or C ₆ Fatty acid esters of sugars, and hydrogenated or non-hydrogenated C ₅ Or C ₆ Polyoxyethylene derivatives of fatty acid esters of sugars. Exemplary fatty acids include stearic acid, palmitic acid, and oleic acid. Exemplary hydrogenated and nonhydrogenated C ₅ And C ₆ Fatty acid esters of sugars (e.g., sorbose, mannose, and arabinose) include, but are not limited to, sorbitan oleates, e.g., sorbitan monooleate, sorbitan dioleate, lossSorbitan trioleate and sorbitan sesquioleate, and sorbitan esters of fatty acids of laurate, palmitate and stearate. Exemplary hydrogenated and nonhydrogenated C ₅ And C ₆ Polyoxyethylene derivatives of fatty acid esters of sugars include, but are not limited to, polysorbate and polyoxyethylene sorbitan esters, which are similar to the hydrogenated and non-hydrogenated fatty acid esters described above, except that an ethylene oxide group is provided on each hydroxyl group.

If an optional silica dispersing aid is used, it is present in an amount of about 0.1% to about 25% by weight, based on the weight of the silica, with about 0.5% to about 20% by weight being suitable, and about 1% to about 15% by weight being also suitable, based on the weight of the silica.

In another embodiment, the pre-silanized silica is pre-hydrophobized by treating the silica in its hydrocolloid form with both an organomercaptosilane and an alkylsilane (the weight ratio of organomercaptosilane to alkylsilane is from 10/90 to 90/10); wherein the alkylsilane has the general formula (I):

X _n -Si-R _4-n (I)，

wherein R is an alkyl group having 1 to 18 carbon atoms, preferably 1 to 8 carbon atoms, such as methyl, ethyl, isopropyl, n-butyl and octadecyl, n is a number from 1 to 3 and X is a group selected from halogen, i.e. chlorine or bromine, preferably chloro, and alkoxy, preferably as (R) ¹ O) -alkoxy, wherein R ¹ Is an alkyl group having 1 to 3 carbon atoms, such as methyl, ethyl and isopropyl, preferably methyl and ethyl, and wherein the organomercaptosilane has the general formula (II):

(X) _n (R ² O) _3-n -Si-R ³ -SH (II)，

wherein X is a group selected from halogen such as chlorine or bromine, preferably a chloro group, and an alkyl group having 1 to 16 carbon atoms, preferably selected from methyl, ethyl, n-propyl and n-butyl; wherein R is ² Is an alkyl group having 1 to 16 carbon atoms, preferably 1 to 4 carbon atoms, preferably selected from methyl and ethyl, and R ³ Having 1 to 16 carbon atomsA child, preferably an alkylene of 1 to 4 carbon atoms, preferably a propylene; wherein n represents an integer from 0 to 3, wherein n preferably represents zero.

Representative alkylsilanes of formula (I) are, for example, trichloromethylsilane, dichlorodimethylsilane, chlorotrimethylsilane, trimethoxymethylsilane, dimethoxydimethylsilane, methoxytrimethylsilane, trimethoxypropylsilane, trimethoxyoctylsilane, trimethoxyhexadecylsilane, dimethoxydipropylsilane, triethoxymethylsilane, triethoxypropylsilane, triethoxyoctylsilane and diethoxydimethylsilane.

Representative organomercaptosilanes of formula (II) are, for example, triethoxysilylpropyl silane, trimethoxymercaptopropyl silane, methyldimethoxymercaptopropyl silane, methyldiethoxypropyl silane, dimethylmethoxymercaptopropyl silane, triethoxysilylethyl silane and tripropoxybutyl propyl silane.

Some examples of pre-silanized silica suitable for use in the practice of the present invention include, but are not limited to, silica that has been pre-treated with mercaptosilane255LD and +.>LP (PPG Industries) silicon dioxide, and organosilane bis (triethoxysilylpropyl) polysulphides (Si 69) and +.>Products of the reaction between VN3 silica8113 (Degussa), and->6508. PPG Industries >400 silicon dioxide, PPG Industries>454 silica, and PPG Industries>458 silica.

In one embodiment, the elastomeric composition does not contain non-pre-silanized silica or contains less than 10phr, preferably less than 5phr, of non-pre-silanized silica.

In general, the pre-silanized silica is not necessarily a pre-silanized precipitated silica here, but is preferably a pre-silanized precipitated silica.

In embodiments, the elastomeric composition may further comprise (non-pre-silanized) silica, which is optionally precipitated silica. Such conventional silica may be characterized, for example, as having a BET surface area measured using nitrogen. In one embodiment, the BET surface area may be in the range of 40 to 600 square meters per gram. In another embodiment, the BET surface area may be from 80 to 300 square meters per gram. Conventional silica may also be characterized by dibutyl phthalate (DBP) absorption values of 100 to 400, or 150 to 300. Conventional silica may be expected to have an average final particle size of 0.01 to 0.05 microns, as determined by electron microscopy, for example, although the size of the silica particles may be even smaller or possibly larger. Various commercially available silicas may be used, such as, for example only, and without limitation, silicas commercially available from PPG Industries under the Hi-Sil trademark with designations 210, 315G, EZ G, and so forth; silica available from Solvay, having, for example, the designations Z1165MP and Premium200MP, etc.; and silica available from Evonik AG, having, for example, the designations VN2 and Ultrasil 6000GR, 9100GR, and the like.

In one embodiment, wherein the elastomer composition contains an added/non-pre-silanized silica (in addition to the pre-silanized silica), the elastomer composition contains an added silica coupling agent (silica coupling agent added to the elastomer composition), wherein the silica coupling agent has a portion that reacts with hydroxyl groups (e.g., silanol groups) on the silica and on the pre-silanized silica and another, different portion that interacts with the elastomer of the elastomer composition. In one embodiment, the silica coupling agent added to the elastomeric composition comprises a bis (3-triethoxysilylpropyl) polysulfide having an average of about 2 to about 4 linking sulfur atoms in its polysulfide bridge.

Representative of the aforementioned silica coupling agents (or in other words silica coupling agents) having a moiety that reacts with hydroxyl groups on the pre-silanized silica and another moiety that interacts with the elastomer may include, for example: (a) bis (3-trialkoxysilylalkyl) polysulfides containing an average of about 2 to about 4, alternatively about 2 to about 2.6, or about 3.2 to about 3.8 sulfur atoms in the connecting bridge thereof, or (B) alkoxy organomercaptosilanes, or (C) combinations thereof. Representative of such bis (3-trialkoxysilylalkyl) polysulfides include bis (3-triethoxysilylpropyl) polysulfide. As noted, for the pre-silanized precipitated silica, the silica coupling agent may desirably be an alkoxy organomercaptosilane. For non-pre-silylated silica, the silica coupling agent may desirably comprise bis (3-triethoxysilylpropyl) polysulfide.

In one embodiment, the elastomeric composition may contain a conventional sulfur-containing organosilicon compound or silane. Examples of suitable sulfur-containing organosilicon compounds have the formula:

Z-Alk-S _n -Alk-Z I

wherein Z is selected from

Wherein R is ¹ Is an alkyl group of 1 to 4 carbon atoms, a cyclohexyl group or a phenyl group; r is R ² An alkoxy group of 1 to 8 carbon atoms or a cycloalkoxy group of 5 to 8 carbon atoms; alk is two of 1 to 18 carbon atomsA hydrocarbon of valence, and n is an integer from 2 to 8. In one embodiment, the sulfur-containing organosilicon compound is a 3,3' -bis (trimethoxy or triethoxysilylpropyl) polysulfide. In one embodiment, the sulfur-containing organosilicon compound is 3,3 '-bis (triethoxysilylpropyl) disulfide and/or 3,3' -bis (triethoxysilylpropyl) tetrasulfide. Thus, for formula I, Z may be

Wherein R is ² Alkoxy of 2 to 4 carbon atoms or 2 carbon atoms; alk is a divalent hydrocarbon of 2 to 4 carbon atoms, alternatively 3 carbon atoms, and n is an integer of 2 to 5 or an integer of 2 or 4. In another embodiment, suitable sulfur-containing organosilicon compounds include those disclosed in U.S. patent application 6,608,125. In one embodiment, the sulfur-containing organosilicon compound comprises 3- (octanoylthio) -1-propyltriethoxysilane, CH ₃ (CH ₂ ) ₆ C(＝O)-S-CH ₂ CH ₂ CH ₂ Si(OCH ₂ CH ₃ ) ₃ As NXT ^TM Commercially available from Momentive Performance Materials. In another embodiment, suitable sulfur-containing organosilicon compounds include those disclosed in U.S. patent publication No. 2003/013055. In one embodiment, the sulfur-containing organosilicon compound is Si-363 from Degussa. The amount of sulfur containing organosilicon compound in the elastomeric composition can vary depending on the level of other additives used. In general, the amount of compound may be from 0.5phr to 20phr. In one embodiment, the amount will be from 1phr to 10phr.

In one embodiment, the elastomeric composition does not contain a separate silica coupling agent, i.e., a silica coupling agent added separately to the rubber composition.

In yet another embodiment, the filler comprises at least 50phr of silica, preferably 50phr to 160phr of silica, wherein the silica is predominantly pre-silanized silica (all by weight).

In another embodiment, the filler comprises from 45phr of the pre-silanized silica to 150phr of the pre-silanized silica. In a preferred embodiment, the filler comprises from 60phr of the pre-silanized silica to 150phr of the pre-silanized silica.

In yet another embodiment, the filler comprises from 25phr of the pre-silanized silica to 60phr of the pre-silanized silica. This range is of particular interest for truck tires.

In yet another embodiment, the filler comprises less than 25phr of carbon black, preferably less than 10phr of carbon black, or even more preferably less than 5phr of carbon black.

In another preferred embodiment, the elastomeric composition comprises at most 10phr of a liquid plasticizer, preferably at most 10phr of an oil. Liquid plasticizer is understood here to mean a plasticizer which is in the liquid state at 23 ℃.

In another preferred embodiment, the elastomeric composition comprises less than 50phr oil, preferably less than 30phr oil, more preferably less than 10phr oil, or even more preferably less than 7phr oil. It may also contain up to less than 5phr oil or be substantially or completely free of oil.

In yet another embodiment, the elastomeric composition further comprises from 3phr to 20phr (preferably from 5phr to 15 phr) of a polyoctenamer. The addition of polyoctenes helps to further improve the tensile properties and co-curability with other diene-based elastomeric compounds. Furthermore, the presence of polyoctenes in combination with partially saturated elastomers such as hydrogenated SSBR helps to improve the rolling resistance index.

In another preferred embodiment, the polyoctenes have one or more of the following: glass transition temperatures ranging from-50 ℃ to-80 ℃ as determined by ASTM D3418 as described below; a weight average molecular weight Mw of 80,000 to 100,000g/mol, determined by Gel Permeation Chromatography (GPC) using polystyrene calibration standards according to ASTM 5296-11 or equivalent; and a melting point of 45 ℃ to 55 ℃ as measured by DSC in a second heating according to ASTM D3418 or equivalent.

In yet another preferred embodiment, the polyoctenes have from 65% to 85% of the trans double bonds of all double bonds in the polyoctenes.

In another embodiment, the elastomeric composition comprises 75phr (preferably 80 phr) to 100phr of a partially saturated elastomer, and/or 0phr to 25phr (preferably 20 phr) of one or more of polybutadiene rubber, polyisoprene, and natural rubber. In particular, a large amount of partially saturated elastomer has been found to be most desirable.

In yet another embodiment, the polybutadiene rubber has a glass transition temperature of from-90 ℃ to-115 ℃ and/or is a (high) cis polybutadiene rubber having a cis microstructure content of at least 95%.

In another embodiment, the composition may comprise one or more hydrogenated plasticizers selected from one or more of a hydrogenated liquid plasticizer and a hydrogenated hydrocarbon resin. In particular, the hydrogenated liquid plasticizer may comprise a hydrogenated oil and/or a hydrogenated liquid polymer, preferably a hydrogenated liquid diene-based polymer. Such hydrogenated liquid and diene-based polymers preferably have an average molecular weight Mw of less than 50,000g/mol, wherein Mw is determined by Gel Permeation Chromatography (GPC) using polystyrene calibration standards according to ASTM 5296-11 or equivalent. The liquid diene-based polymer may include liquid styrene-butadiene rubber, isoprene rubber, styrene isoprene rubber, isoprene butadiene rubber, and styrene isoprene butadiene rubber, or a combination thereof.

In one embodiment, the hydrogenated hydrocarbon resin is selected from the group consisting of fully or partially hydrogenated C9 resins, fully or partially hydrogenated C5 resins, fully or partially hydrogenated alpha-methylstyrene resins, fully or partially hydrogenated terpene resins, fully or partially hydrogenated rosin resins, or mixtures thereof. The resin may also be modified with one or more aliphatic or aromatic groups.

In another embodiment, the hydrogenated hydrocarbon resin is selected from the group consisting of fully or partially hydrogenated (especially aliphatic) C5 resins, fully or partially hydrogenated cyclopentadiene resins, fully or partially hydrogenated dicyclopentadiene resins, and combinations thereof. The resin may also be modified with one or more aliphatic or aromatic groups. However, the majority of the monomer residues of the resin are preferably partially or fully hydrogenated cyclopentadiene, fully or partially hydrogenated dicyclopentadiene, and combinations thereof.

In yet another embodiment, the hydrogenated hydrocarbon resin does not contain double bonds. Such highly hydrogenated hydrocarbon resins are even more compatible with the rubber matrix according to the invention.

In another embodiment, the hydrogenated hydrocarbon resin is a fully or partially hydrogenated cyclopentadiene resin, a fully or partially hydrogenated dicyclopentadiene, or a combination thereof.

In another embodiment, the elastomeric composition may comprise at least one resin, preferably a hydrocarbon resin, even more preferably a plasticized hydrocarbon resin (e.g., a hydrogenated hydrocarbon resin as described herein above). The resin may be present in an amount of from 5phr to 80phr, preferably from 10phr to 75phr, or even more preferably from 20phr to 70 phr.

In another embodiment, the glass transition temperature of the resin is from 30 ℃ to 80 ℃, preferably from 40 ℃ to 80 ℃, or even more preferably from 40 ℃ to 70 ℃. The glass transition temperature of the resin is herein measured by Differential Scanning Calorimeter (DSC) as the midpoint of the peak at a rate of rise of 10℃per minute, according to ASTM D6604 or equivalent.

In another embodiment, the resin has a softening point of at least 95 ℃ as determined according to ASTM E28 or equivalent, which may sometimes be referred to as the ring and ball softening point. Preferably, the softening point is at most 140 ℃ or more preferably at most 120 ℃, or even more preferably at most 110 ℃.

In yet another embodiment, the polydispersity index of the resin is from 1 to 5, preferably from 1 to 2, or even more preferably from 1.5 to 1.8.

In yet another embodiment, the resin has an average molecular weight Mw of 150g/mol to 1500g/mol, preferably 400g/mol to 1000g/mol, or more preferably 500g/mol to 900g/mol or even more preferably 600g/mol to less than 700 g/mol. Mw is determined by Gel Permeation Chromatography (GPC) using polystyrene calibration standards according to ASTM 5296-11 or equivalent.

In yet another embodiment, the elastomeric composition further comprises at least 0.2phr of a vulcanizing agent, preferably comprising elemental sulfur. For example, the composition may comprise from 0.4phr to 15phr of a vulcanizing agent, which may comprise, but is not limited to, elemental sulfur or sulfur-containing silanes.

In another embodiment, the elastomeric composition comprises from 0.3phr to 3phr of at least one vulcanization accelerator selected from dithiocarbamate accelerators and/or thiuram accelerators. Such accelerators are known to be fast accelerators and are considered herein to be particularly beneficial in view of the limited amount of double bonds used in the elastomer and/or hydrogenated resin. The composition may comprise further accelerators.

In yet another embodiment, the vulcanization accelerator is tetrabenzyl thiuram disulfide, which has proven to be a preferred choice in combination with partially saturated polymers.

In one embodiment, the elastomeric composition may comprise at least one and/or one additional diene-based rubber. Representative synthetic polymers may be homo-and copolymers of butadiene and its homologs and derivatives, such as methyl butadiene, dimethyl butadiene and pentadiene, as well as copolymers, such as those formed from butadiene or its homologs or derivatives with other unsaturated monomers. Among the latter may be acetylene, such as vinyl acetylene; olefins, such as isobutylene, which copolymerizes with isoprene to form butyl rubber; vinyl compounds such as acrylic acid, acrylonitrile (which polymerize with butadiene to form NBR), methacrylic acid and styrene, the latter compound polymerizing with butadiene to form SBR, and vinyl esters and various unsaturated aldehydes, ketones and ethers such as acrolein, methyl isopropenyl ketone and vinyl ethyl ether. Specific examples of synthetic rubbers include neoprene (polychloroprene), polybutadiene (including cis-1, 4-polybutadiene), polyisoprene (including cis-1, 4-polyisoprene), butyl rubber, halobutyl rubber such as chlorobutyl rubber or bromobutyl rubber, styrene/isoprene/butadiene rubber, copolymers of 1, 3-butadiene or isoprene with monomers such as styrene, acrylonitrile and methyl methacrylate, and ethylene/propylene terpolymers, also known as Ethylene Propylene Diene Monomer (EPDM), and in particular ethylene/propylene/dicyclopentadiene terpolymers. Additional examples of rubbers that may be used include alkoxy-silyl end-functionalized solution polymerized polymers (SBR, PBR, IBR and SIBR), silicon-coupled and tin-coupled star-branched polymers. Preferred rubbers or elastomers may generally be natural rubber, synthetic polyisoprene, polybutadiene, and SBR, including SSBR. One or more of these rubbers may be functionalized, for example for coupling to silica.

In another embodiment, the composition may comprise at least two diene-based rubbers. For example, combinations of two or more rubbers are preferred, such as cis 1, 4-polyisoprene rubber (natural or synthetic, but preferably natural), 3, 4-polyisoprene rubber, styrene/isoprene/butadiene rubber, emulsion and solution polymerization derived styrene/butadiene rubber, cis 1, 4-polybutadiene rubber, and emulsion polymerization prepared butadiene/acrylonitrile copolymers. In some embodiments, the partially saturated elastomer may also be a diene-based polymer, but it need not be.

In another embodiment, emulsion polymerization derived styrene/butadiene (ESBR) having a styrene content of 20% to 35% bound styrene may be used, or for some applications, ESBR having a medium to relatively high bound styrene content, i.e., 30% to 45% bound styrene content. ESBR prepared by emulsion polymerization may represent copolymerization of styrene and 1, 3-butadiene in the form of an aqueous emulsion. These are well known to those skilled in the art. The bound styrene content may vary, for example, from 5% to 50%. In one aspect, the ESBR may also contain acrylonitrile to form a terpolymer rubber, such as ESBR, in an amount of, for example, 2 to 30 weight percent bound acrylonitrile in the terpolymer. Styrene/butadiene/acrylonitrile copolymer rubbers prepared by emulsion polymerization containing 2 to 40 wt.% bound acrylonitrile in the copolymer may also be considered diene-based rubbers.

In another embodiment, solution polymerization prepared SBR (SSBR) may be used. Such SSBR may for example have a bound styrene content of 5-50%, preferably 9-36%. SSBR may conveniently be prepared, for example, by anionic polymerization in an inert organic solvent. More specifically, SSBR can be synthesized by copolymerizing styrene and 1, 3-butadiene monomers in a hydrocarbon solvent using an organolithium compound as an initiator. As mentioned above, such rubbers may also be functionalized to couple to silica.

In one embodiment, synthetic or natural polyisoprene rubber may be used. The synthesis of cis 1, 4-polyisoprene and cis 1, 4-polyisoprene natural rubber per se is well known to those skilled in the rubber art. In particular, the cis 1, 4-content may be at least 90%, optionally at least 95%.

In one embodiment, cis 1, 4-polybutadiene rubber (BR or PBD) is used. Suitable polybutadiene rubbers may be prepared, for example, by organic solution polymerization of 1, 3-butadiene. BR can conveniently be characterized, for example, by having a cis 1, 4-content of at least 90% (high cis content) and a glass transition temperature Tg of from-95℃to-110 ℃. Suitable polybutadiene rubbers are commercially available, e.g. from The Goodyear Tire &Rubber Company1207、/>1208、/>1223 or->1280. These high cis-1, 4-polybutadiene rubbers can be synthesized, for example, using a nickel catalyst system comprising a mixture of (1) an organonickel compound, (2) an organoaluminum compound, and (3) a fluorine-containing compound, as described in U.S. patent 5,698,643 and U.S. patent 5,451,646.

The glass transition temperature or Tg of an elastomer or rubber means one or more glass transition temperatures of the corresponding elastomer or rubber in its uncured state. The glass transition temperature or Tg of an elastomer composition or rubber composition means the glass transition temperature of the corresponding elastomer composition or rubber composition in its cured state. Tg is measured as the midpoint of the peak by Differential Scanning Calorimeter (DSC) at a rate of temperature increase of 20℃per minute according to ASTM D3418.

The term "phr" as used herein and in accordance with conventional practice refers to "parts by weight of each material per 100 parts by weight of rubber or elastomer". Typically, using this convention, the elastomeric composition comprises 100 parts by weight of rubber/elastomer. The claimed compositions may contain other rubbers/elastomers than those explicitly mentioned in the claims, provided that the phr values of the claimed rubbers/elastomers are consistent with the claimed phr ranges and that the amounts of all rubbers/elastomers in the composition result in a total of 100 parts rubber. In one example, the composition may further comprise from 1phr to 10phr, optionally from 1phr to 5phr, of one or more additional diene-based rubbers, such as SBR, SSBR, ESBR, PBD/BR, NR and/or synthetic polyisoprenes. In another example, the composition may comprise less than 5phr, preferably less than 3phr, of an additional diene-based rubber, or may also be substantially free of such additional diene-based rubber. The terms "size" and "composition" are used interchangeably herein unless otherwise indicated. The terms "rubber" and "elastomer" are also used interchangeably herein unless otherwise indicated.

In one embodiment, the elastomeric composition further comprises an oil, in particular a processing oil. Processing oils may be included in the elastomeric composition as extender oils commonly used to fill elastomers. Processing oils may also be included in the elastomeric composition by adding the oil directly during the rubber compounding process. The process oil used may include both extender oil present in the elastomer and process oil added during compounding. Suitable process oils may include a variety of oils known in the art, including aromatic, paraffinic, naphthenic, vegetable, and low PCA oils, such as MES, TDAE, SRAE and heavy naphthenic oils. Suitable low PCA oils may include those having a polycyclic aromatic content of less than 3 percent by weight as determined by the IP346 method. Procedures for the IP346 method can be found in Standard Methods for Analysis & Testing of Petroleum and Related Products and British Standard 2000parts,2003, 62 nd edition, the Institute of Petroleum, published, united Kingdom.

In one embodiment, the elastomeric composition may further comprise carbon black as one of the filler materials. Preferred amounts in the context of the present application are from 0.5phr to 25phr, preferably from 0.5phr to 10phr or from 0.5phr to 5phr. Representative examples of such carbon blacks include grades N110, N121, N134, N220, N231, N234, N242, N293, N299, N315, N326, N330, N332, N339, N343, N347, N351, N358, N375, N539, N550, N582, N630, N642, N650, N683, N754, N762, N765, N774, N787, N907, N908, N990, and N991. These blacks have an iodine absorption of 9g/kg to 145g/kg and 34cm ³ /100g-150cm ³ DBP value of/100 g.

In another embodiment, other fillers may be used in the elastomeric composition, including but not limited to particulate fillers, including Ultra High Molecular Weight Polyethylene (UHMWPE), crosslinked particulate polymer gels, including but not limited to those disclosed in U.S. Pat. No. 6,242,534, U.S. Pat. No. 6,207,757, U.S. Pat. No. 6,133,364, U.S. Pat. No. 6,372,857, U.S. Pat. No. 5,395,891, or U.S. Pat. No. 6,127,488, and plasticized starch composite fillers, including but not limited to those disclosed in U.S. Pat. No. 5,672,639. Such other fillers may be used in amounts of 1phr to 10 phr.

It will be readily appreciated by those skilled in the art that the elastomeric compositions may be compounded by methods generally known in the rubber compounding art, such as mixing the various sulfur-vulcanizable constituent rubbers with various commonly used additive materials such as, for example, sulfur donors, curing aids such as activators and scorch retarders, and processing additives such as oils, resins and plasticizers including tackifying resins, fillers, pigments, fatty acid, zinc oxide, waxes, antioxidants, and antiozonants, as well as peptizing agents. The additives mentioned above are selected and generally used in conventional amounts, as known to the person skilled in the art, depending on the intended use of the sulfur-vulcanizable and sulfur-vulcanized material (rubber). Representative examples of sulfur donors include elemental sulfur (free sulfur), amine disulfides, polymeric polysulfides, and sulfur olefin adducts. In one embodiment, the sulfur-vulcanizing agent is elemental sulfur. The sulfur-vulcanizing agent may be used, for example, in an amount of 0.5phr to 8phr, alternatively 1.5phr to 6 phr. Typical amounts of tackifier resins, if used, comprise, for example, 0.5phr to 10phr, typically 1phr to 5phr. Typical amounts of processing aids, if used, include, for example, 1phr to 50phr (which may include, inter alia, oil). Typical amounts of antioxidants, if used, may comprise, for example, from 1phr to 5phr. Representative antioxidants may be, for example, diphenyl-p-phenylenediamine and others, such as those disclosed, for example, in pages 344-346 of The Vanderbilt Rubber Handbook (1978). Typical amounts of antiozonants, if used, may comprise, for example, 1phr to 5phr. Typical amounts of fatty acids, if used, may include stearic acid, and may include, for example, 0.5phr to 3phr. Typical amounts of wax, if used, may include, for example, 1phr to 5phr. Microcrystalline waxes are commonly used. Typical amounts of peptizers, if used, may comprise, for example, 0.1phr to 1phr. Typical peptizers may be, for example, pentachlorothiophenol and dibenzoyl aminodiphenyl disulfide.

Accelerators may be preferred, but are not necessary to control the time and/or temperature required for vulcanization and to improve the properties of the vulcanizate. In one embodiment, a single accelerator system, the primary accelerator, may be used. The primary accelerator(s) may be used in a total amount of 0.5phr to 4phr, alternatively 0.8phr to 1.5 phr. In another embodiment, a combination of primary and secondary accelerators may be used, with the secondary accelerator being used in a smaller amount, for example 0.05phr to 3phr, to activate and improve the properties of the vulcanizate. The combination of these accelerators may be expected to produce a synergistic effect on the final properties and are somewhat better than those produced by either accelerator alone. In addition, a slow acting accelerator may be used which is not affected by normal processing temperatures but produces satisfactory cure at ordinary vulcanization temperatures. Vulcanizing scorch retarders may also be used. Suitable types of accelerators useful in the present invention are, for example, amines, disulfides, guanidines, thioureas, thiazoles, thiurams, sulfenamides, dithiocarbamates and xanthates. In one embodiment, the primary accelerator is a sulfenamide. If a secondary accelerator is used, the secondary accelerator may be, for example, a guanidine, dithiocarbamate or thiuram compound. Suitable guanidines include diphenylguanidine (dipheyyguanidine) and the like. Suitable thiurams include tetramethylthiuram disulfide, tetraethylthiuram disulfide, and tetrabenzylthiuram disulfide.

The mixing of the elastomer composition may be accomplished by methods known to those skilled in the rubber mixing art. For example, the ingredients may generally be mixed in at least two stages, namely at least one non-productive stage followed by a productive mixing stage. The final curative, including the sulfur-vulcanizing agent, may generally be mixed in a final stage, commonly referred to as a "productive" mixing stage, where the mixing is typically conducted at a temperature or final temperature that is lower than the mixing temperature or temperatures of the preceding non-productive mixing stage or stages. The terms "non-productive" and "productive" mix stages are well known to those skilled in the rubber mixing arts. In one embodiment, the elastomeric composition may be subjected to a thermomechanical mixing step. The thermomechanical mixing step typically comprises mechanical processing in a mixer or extruder for a period of time, for example, a period of time suitable to produce a rubber temperature of 140 ℃ to 190 ℃. The appropriate duration of the thermo-mechanical processing varies with operating conditions and the volume and nature of the component. For example, the thermo-mechanical processing may be 1 to 20 minutes.

The elastomeric composition may be incorporated into various rubber components, such as the rubber components of a tire (or in other words, the tire components). For example, the rubber component may be a tread (including tread cap and base tread), sidewall, apex, chafer, sidewall insert (sidewall insert), cord encapsulation (wirecoat), or innerliner. Tread rubber applications are preferred applications of the present invention.

In a second aspect of the invention, a vulcanized elastomeric composition is provided, which is based on the elastomeric composition according to the first aspect of the invention. In other words, the vulcanized elastomeric composition is the vulcanization product of the sulfur-vulcanizable elastomeric composition according to the first aspect and/or embodiments thereof.

In a third aspect of the present invention, there is provided a rubber component, preferably for a tyre, comprising in particular an elastomeric composition according to the first aspect of the present invention or according to one or more of the second aspect of the present invention and/or embodiments thereof. Thus, the tire may be an uncured tire or a cured tire, i.e., a vulcanized tire.

In a fourth aspect of the present invention, there is provided a tire comprising the rubber composition according to the first or second aspect of the present invention, or having the rubber component according to the third aspect of the present invention.

In a preferred embodiment, the tire comprises a tread, preferably a tread cap, comprising the elastomeric composition. In another embodiment, the tire has a radially outer tread running surface layer (radially outertread cap layer) comprising an elastomeric composition, which is intended to be in contact with the road while running.

The tire of the present invention may be, for example, a pneumatic or non-pneumatic tire, a racing tire, a passenger tire, an aircraft tire, an agricultural tire, a bulldozer tire, an off-the-road (OTR) tire, a truck tire, or a motorcycle tire. The tire may also be a radial or bias tire.

The vulcanization of the pneumatic tire may be carried out, for example, at a conventional temperature of 100 ℃ to 200 ℃. In one embodiment, the vulcanization is carried out at a temperature of 110 ℃ to 180 ℃. Any conventional vulcanization method may be used, such as heating in a press or mold, heating with superheated steam or hot air. Such tires can be manufactured, shaped, molded, and cured by various methods that are known and will be apparent to those skilled in the art.

Further, in a fifth aspect, the present invention relates to a process for preparing an elastomeric composition (e.g. an elastomeric composition as described in the preceding aspects), the process comprising one or more of the following steps:

i) Silylation of the silica with at least one silane to obtain a silylated (or in other words pre-silylated) silica;

ii) adding the silanized silica to a partially saturated elastomer and/or diene-based elastomer;

iii) Mixing the silanized silica with a partially saturated elastomer and/or a diene-based elastomer;

iv) adding one or more of plasticizers (e.g. resins and/or oils), processing aids, antidegradants, waxes;

v) adding sulfur and optionally at least one (sulfur curing) accelerator.

In a sixth aspect, the present invention relates to a process for manufacturing tyres, preferably with a composition according to the previous aspect and/or with a composition prepared with a process for preparing an elastomeric composition according to the fifth aspect, wherein the process for manufacturing tyres comprises:

a) Forming at least a portion of a rubber component (or rubber component) with a vulcanizable elastomeric composition;

b) Assembling a tire comprising a rubber component;

c) Curing the tire with the rubber component to obtain a cured tire.

The various features of the aspects and embodiments mentioned herein may be combined with one another.

Examples

Table 1 below shows two comparative elastomer compositions that are not according to the invention. Comparative example 1 shows a rubber composition comprising the same diene-based rubber matrix as comparative example 2. Most of the ingredients of both compositions are identical. However, comparative example 1 contained 80phr of conventional silica and 7phr of silane 1, while comparative example 2 had 90phr of pre-silanized silica. In addition, comparative example 1 contained 10phr oil, while comparative example 2 contained 5phr oil. For example, these two comparative examples demonstrate that the use of pre-silanized silica instead of a comparable amount of conventional, i.e., non-pre-silanized, silica generally reduces the stiffness of the compound. This effect is shown in table 2 herein below.

TABLE 1

/>

¹ Solution polymerized styrene butadiene rubber, e.g. SLR4602 from Trinseo

² Polybutadiene rubber, e.g. Buden from Goodyear ^TM 1223

³ Polyterpene resins, e.g. Sylvatraxx 4150 from Arizona Chemical

⁴ TDAE oil

⁵ Zinc soaps comprising monoglycerides of stearic acid and fatty acids

⁶ Precipitated silicas, e.g. Zeosil from Solvay ^TM Premium 200MP

⁷ Pre-silanized precipitated silica, e.g. Agilon from PPG Industries ^TM 400

⁸ Bis-triethoxysilylpropyl disulfide, e.g. SI266 from Evonik ^TM

⁹ Based on phenylenediamine

¹⁰ Diphenylguanidine (accelerator)

¹¹ N-cyclohexyl-2-benzothiazole sulfenamide (accelerator)

¹² 50% bis-triethoxysilylpropyl tetrasulfide on 50% N330 carbon black support, e.g. X50S from Evonik

TABLE 2

Properties of (C)	Comparative example 1	Comparative example 2
			G’(1％)，1Hz[MPa] ^a	2.2	1.5
Tanδ(6％)，30℃ ^b	0.22	0.19
			Tensile Strength [ MPa ]] ^c	21	21

^a G' is RPA 2000 from Alpha Technologies ^TM Rubber Process Analyzer, obtained at 1% strain, 100℃and 1Hz frequency based on ASTM D5289

^b Tandelta is measured by Metravib at a temperature of 30 DEG C ^TM The instrument was obtained on DIN 53513 or equivalent at 6% strain and 7.8Hz

^c Tensile strength is determined by ring sample testing based on ASTM D412 or equivalent, tensile strength is stress at break

The stiffness of comparative example 2 was observed to be significantly less than that of comparative example 1, as indicated by a reduction in G' of about 32%. This decrease in stiffness was even more pronounced because the composition of comparative example 2 already had an increased silica content (at 10 phr), with more filler generally increasing the stiffness of the composition. Even more, comparative example 2 has 5phr less oil than comparative example 1, which also generally increases compound stiffness. The pre-silanized silica is better dispersed in the elastomeric composition, which results in reduced stiffness at low strain.

As shown in table 2, tan delta was increased by about 14% by using the pre-silanized silica. Tan delta can be considered a hysteresis indicator so its reduction also indicates a reduced rolling resistance if the same elastomeric composition is used in a tire. The tensile strength of comparative example 1 and comparative example 2 remained the same and relatively low.

While the above-described improvement in Tan delta is desirable, a significant decrease in stiffness may be undesirable, for example, for many performance oriented tire applications.

According to an embodiment of the present invention, the inventors found examples 1 and 2 of the present invention as shown in table 3 below. Inventive examples 1 and 2 are listed together with comparative examples 3 and 4 which are not according to the invention. All examples of table 3 contain partially saturated elastomers in the form of hydrogenated solution polymerized styrene-butadiene rubber. Furthermore, inventive examples 1 and 2 contained pre-silanized silica, while comparative examples 3 and 4 contained conventional silica, similar to comparative examples 1 and 2. Comparative example 3 and inventive example 1 each comprise a high Tg hydrogenated solution polymerized styrene-butadiene rubber. Comparative example 4 and inventive example 2 each comprise a low Tg hydrogenated solution polymerized styrene-butadiene rubber.

TABLE 3 Table 3

¹³ Hydrogenated solution polymerized styrene-butadiene rubber having Tg of-30 ℃, such as NT120 from JSR

¹⁴ Hydrogenated solution polymerization of styrene butadiene rubber having Tg of-53 ℃,

¹⁵ such as Vestenamer from Evonik ^TM

¹⁶ Tetrabenzyl thiuram disulfide (accelerator)

¹⁷ 2-mercaptobenzothiazole (promoter)

The stiffness, tan delta and tensile strength of the examples of table 3 were determined and are listed in table 4 below.

TABLE 4 Table 4

As shown in table 4, the stiffness of inventive example 1 was significantly higher than its associated comparative example 3. This surprising and unexpected effect is quite different from that observed with the combination of conventional diene-based rubber and pre-silanized silica. For example, comparative examples 1 and 2 in table 2 have demonstrated this typical phenomenon, where the opposite effect of stiffness reduction occurs when the conventional silica is replaced with a pre-silanized silica. However, when the pre-silanized silica is used in combination with a partially saturated elastomer (here in the form of a hydrogenated solution polymerized styrene-butadiene rubber), the stiffness may even increase when the conventional silica is replaced by the pre-silanized silica. The same phenomenon can be observed when comparing the stiffness values of comparative example 4 and inventive example 2, as also shown in table 4. Furthermore, each Tan δ value, which is an indicator of hysteresis/rolling resistance, is significantly improved after deployment of the pre-silanized silica compared to the use of conventional silica. In addition, comparative examples 3 and 4 and inventive examples 1 and 2 show good tensile strength.

In general, inventive examples 1 and 2 have advanced stiffness, good rolling resistance index, and at the same time good tensile properties.

Claims

1. A sulfur-vulcanizable elastomeric composition characterized by:

50phr to 100phr of at least one partially saturated elastomer characterized by repeat units, characterized in that up to 15% of all repeat units of the partially saturated elastomer comprise double bonds;

from 0phr to 50phr of at least one diene-based elastomer; and

40phr to 200phr of at least one filler, characterized in that the filler comprises mainly silanized silica or pre-silanized silica.

2. The elastomer composition according to claim 1, characterized in that the glass transition temperature of the partially saturated elastomer is from-20 ℃ to-65 ℃; and/or characterized in that the partially saturated elastomer has a weight average molecular weight Mw of 200,000g/mol to 500,000 g/mol.

3. The elastomeric composition of claim 1, wherein the elastomeric composition comprises from 0phr to 10phr of the liquid plasticizer or from 2phr to 10phr of the liquid plasticizer.

4. The elastomeric composition of claim 1, wherein the silanized or pre-silanized silica has a particle size of less than 120g/m ² Is a BET surface area of (C).

5. The elastomeric composition of claim 1, wherein the pre-silanized silica is silica pre-reacted with a sulfur-containing silane; or characterized in that the silanized silica is silica reacted with a sulfur-containing silane.

6. The elastomeric composition according to claim 1, characterized in that said filler comprises 45phr to 150phr of said silica; and/or characterized in that said filler comprises less than 5phr of carbon black.

7. The elastomeric composition according to claim 1, characterized in that at most 11% of all the repeating units have double bonds and/or in that at least 4% of the repeating units have double bonds.

8. The elastomeric composition of claim 1, further characterized by 3phr to 20phr of polyoctene.

9. The elastomeric composition of claim 1, further characterized by 0.1phr to 3phr of a vulcanization accelerator selected from one or more of a dithiocarbamate accelerator and a thiuram accelerator.

10. Tyre with a rubber component, such as a tread, characterized in that the elastomeric composition according to one of the preceding claims is vulcanized.