Rubber composition containing block copolymer and block copolymer

Abstract

The present invention discloses a rubber composition and a block copolymer comprising a block copolymer. A rubber composition is disclosed, comprising an elastomer, a filler and a block copolymer, wherein the block copolymer comprises an elastomeric block and a thermoplastic block comprising a polyalkyl acrylate. The polyalkyl acrylate contains a single bond oxygen atom. The alkyl acrylate contains a polycyclic substituent on its single bond oxygen atom. The rubber composition can be used for an article selected from tires, power transmission belts, hoses, tracks, air sleeves and conveyor belts. A block copolymer is also disclosed, comprising an elastomeric block and a thermoplastic block comprising a polyalkyl acrylate. The polyalkyl acrylate contains a single bond oxygen atom. The alkyl acrylate contains a polycyclic substituent on its single bond oxygen atom. The block copolymer is a diblock copolymer.

Description

Technical Field

[0001] The present invention relates to a rubber composition, in particular a sulfur-vulcanizable or sulfur-vulcanized rubber composition, comprising a block copolymer. In addition, the present invention relates to a rubber product, such as a tire or a tire component, comprising the rubber composition, and to a block copolymer. Background Art

[0002] Rubber compositions, particularly for tires but not limited to rubber compositions of this application, need to meet multiple requirements, such as durability, rigidity, elasticity, low hysteresis and more. In order to further improve the properties of rubber compositions for certain applications, it has been suggested to use ultra-high molecular weight polyethylene (UHMWPE) in the past. However, although the use of polyethylene materials helps to improve rubber properties, such as rigidity, in some applications, its use also has some inherent disadvantages. For example, one problem is its relatively low melting point, which can be problematic in many rubber compositions at the order of 135°C. Another disadvantage related to polyethylene being compounded into rubber formulations is that it is difficult to process and disperse it in rubber formulations, thereby limiting the required reinforcement effect due to relatively poor dispersion. In addition, rigidity can also be improved by providing suitable organic or inorganic filler materials. However, increasing the amount of this filler to a higher level can also have multiple disadvantages, such as weight gain, problems during mixing, etc. Although there are many methods for providing rubber compositions with high rigidity, there is still significant room for improvement. Summary of the invention

[0003] The invention relates to a rubber composition according to claim 1, a product according to claim 8, and a block copolymer according to claim 9.

[0004] The dependent claims relate to preferred embodiments of the invention.

[0005] A first object of the present invention is to provide an advanced reinforced rubber composition and material thereof, particularly a reinforced rubber composition and material thereof for tire components.

[0006] Another object of the present invention may be to provide a rubber composition having high stiffness with limited hysteresis and / or weight.

[0007] Another object of the present invention is to obtain small phase sizes compared to blending of conventional thermoplastic materials such as UHMWPE.

[0008] In one aspect of the present invention, a rubber composition is provided, the rubber composition comprising an elastomer, a filler and a block copolymer. According to the present invention, the block copolymer has an elastomer block and a thermoplastic block comprising a polyalkyl acrylate, wherein the alkyl acrylate comprises a polycyclic substituent on its single-bonded oxygen atom.

[0009] It has been found that providing the block copolymer material reduces the phase size in the rubber composition, particularly compared with other conventional thermoplastic reinforcements (reinforcement) such as UHMWPE. The block copolymer with an elastomer block is compatible with other elastomers in the rubber composition. In addition, according to the non-constrained theory of the inventors, the polyalkyl acrylate connected to the elastomer block (covalently) bonded or in other words connected to the other components of the rubber composition such as filler is connected. In addition, the provision of polyalkyl acrylate enhances the rubber compound, wherein its substituent significantly limits the chain mobility in the rubber compound. In a word, block copolymers help to provide enhancement, particularly at a weight or density lower than conventional filler materials, respectively. These block copolymers also have fewer disadvantages than other thermoplastic reinforcements such as above-mentioned UHMWPE in terms of high temperature thermal stability.

[0010] In a preferred embodiment, the elastomer and / or the elastomer block comprises or consists of at least one diene-based elastomer.

[0011] Preferably, the diene-based elastomer is selected from one or more of styrene-butadiene rubber, polybutadiene, solution-polymerized styrene-butadiene rubber, emulsion-polymerized styrene-butadiene rubber, natural rubber, synthetic polyisoprene rubber, and isoprene-butadiene rubber. The diene-based elastomer may be based on monomer residues, such as one or more of butadiene, styrene, and isoprene. Providing such an elastomer block helps improve compatibility with other rubbers or diene-based elastomers in the rubber composition.

[0012] In a preferred embodiment, the block copolymer has exactly, or in other words, only two blocks, namely an elastomeric block and a thermoplastic block. In yet other words, the block copolymer is a diblock copolymer.

[0013] In a preferred embodiment, the elastomer or elastomer block has a functional group for coupling to the surface of one of silica and carbon black. Such groups can be selected, for example, from one or more of aminosilanes, aminosiloxanes, mercaptosilanes, mercaptosiloxanes, silanols, alkoxysilanes, alkoxythio / thiol, epoxy and hydroxy groups, particularly coupled to silica. These groups even further improve bonding and / or enhancement in the rubber composition, particularly to filler networks containing silica.

[0014] In a preferred embodiment, the elastomeric block comprises an elastomeric chain having a first chain end and a second chain end, wherein the first chain end is attached to the polyalkylacrylate block, wherein the functional group is located at the second chain end.

[0015] In a preferred embodiment, the functional groups are located at the chain ends of the elastomeric blocks which are not attached to the thermoplastic blocks.

[0016] In a preferred embodiment, the polyalkyl acrylate has the following structure:

[0017]

[0018] wherein n is the number of alkyl acrylate monomers (or monomer residues, respectively) in the polyalkyl acrylate; R 1 is O or alkyl; and R 2 It is a polycyclic hydrocarbon substance.

[0019] Preferably, n is an integer greater than 10, preferably greater than 50, and preferably less than 2000, preferably less than 1500.

[0020] It has been found that this material has a large substituent R 2 (which may for example further contribute to improving the stiffness of the compound) and is even more desirable. In addition, polyalkyl acrylates with their bulky side groups / substituents contribute to improved processing properties (also due to their amorphous nature) and also have relatively high heat resistance, or in other words, a relatively high thermal transition point.

[0021] Generally, the block copolymers proposed can provide advanced reinforcement of the rubber matrix with limited hysteresis. In addition, when considering the realization of similar reinforcement degree, the proposed alkyl acrylate is a relatively lightweight material compared with silica or carbon black. In particular, these properties or their combination can be not easily achieved by providing more carbon black or silica in the rubber composition. Adding more of this material can increase weight or density respectively, and / or increase hysteresis. In addition, this can make mixing more difficult, or can also change other properties of the rubber compound in an undesirable manner.

[0022] In a preferred embodiment, the alkyl group is a methyl group (—CH 3 ) or ethyl (-C 2 H 5 ).

[0023] In a preferred embodiment, the alkyl acrylate has one of a bicyclic substituent and a tricyclic substituent on its single-bonded oxygen atom.

[0024] In a preferred embodiment, the alkyl acrylate has a hydrocarbon substituent on its singly bonded oxygen atom, the hydrocarbon substituent comprising at least seven carbon atoms, at least five of which are arranged in a ring.

[0025] In a preferred embodiment, the alkyl acrylate has a hydrocarbon substituent containing at least seven carbon atoms, optionally at least eight carbon atoms, wherein at least five (optionally at least six) of the carbon atoms are arranged in a ring. These have proven to be desirable materials.

[0026] In a preferred embodiment, the polyalkyl acrylate is one of poly(isobornyl methacrylate) (also referred to herein as PIBOMA) and poly(adamantyl methacrylate) (also referred to herein as PADAM). These materials have been identified by the inventors as two materials that have the most desirable properties for one of the blocks of the copolymer, particularly in terms of reinforcement. In addition, large side groups or substituents help improve processing properties and provide a relatively high glass transition temperature, which can be an indicator of the heat resistance of the material in the vulcanized rubber.

[0027] In a preferred embodiment, the polyalkylacrylate comprises one or more of the following structures (wherein n is an integer, preferably equal to and / or greater than 3, or even more preferably greater than 10):

[0028] .

[0029] In a preferred embodiment, the thermoplastic (polymer) block consists of a polyalkyl acrylate and has one or more of: i) a number average molecular weight Mn of at least 10,000 g / mol, optionally at least 15,000 or 20,000 g / mol; and ii) at least 10, preferably at least 50 monomers (or monomer residues) of said alkyl acrylate. It has been found that such a minimum weight may be desirable to observe a greater effect on reinforcement and to avoid too low a thermal transition point.

[0030] Mn and / or Mw (weight-average molecular weight) are determined here by GPC according to ASTM standard D5296 using polystyrene calibration standards.

[0031] In a preferred embodiment, the thermoplastic (polymer) block consists of a polyalkylacrylate and has one or more of: (i) a number average molecular weight Mn of at most 450,000 g / mol, preferably at most 150,000 g / mol, or still more preferably at most 100,000 g / mol, or even more preferably 90,000 g / mol; and (ii) at most 6000, preferably at most 2000, still preferably at most 1500, or even more preferably at most 500 or at most 400 monomer residues of the alkylacrylate.

[0032] In a preferred embodiment, the elastomeric blocks, or in other words, the elastomeric chains, have one or more of: (i) a number average molecular weight Mn of at least 10,000 g / mol, preferably at least 20,000 g / mol, or even more preferably at least 50,000 g / mol; and (ii) at least 90, or preferably at least 300, monomers selected from styrene, butadiene and isoprene.

[0033] In a preferred embodiment, the elastomeric blocks, or in other words elastomeric chains, have one or more of: (i) a number average molecular weight Mn of at most 150,000 g / mol, preferably at most 120,000 g / mol; and (ii) at most 2500, or preferably at most 2000, or even more preferably at most 1500 monomers selected from the group consisting of styrene, butadiene and isoprene.

[0034] In a preferred embodiment, the ratio of the number average molecular weights of the elastomeric block to the thermoplastic block is from 0.5 to 3, preferably from 0.5 to 2.5.

[0035] In a preferred embodiment, the ratio of the number average molecular weight of the elastomer block and the thermoplastic block is in the range of 0.1 to 1, preferably in the range of 0.1 to 0.95, and even more preferably in the range of 0.25 to 0.8, or even more preferably in the range of 0.25 to 0.5. In other words, the weight of the elastomer block is relatively small compared to the weight of the thermoplastic block. This allows the block copolymer to be used in a flexible manner in different types of rubber compositions. In particular, with respect to the specific properties of the elastomer block, it adds a limited weight or amount of elastomeric material to the composition.

[0036] In a preferred embodiment, the polydispersity index (Mw / Mn) of the block copolymer is in the range of 1.03 to 3, preferably in the range of 1.05 to 2, and even more preferably in the range of 1.05 to 1.6.

[0037] In a preferred embodiment, the block copolymer has a first glass transition temperature in the range of -92°C to -15°C and a second glass transition temperature in the range of 150°C to 250°C.

[0038] The glass transition temperature was determined by TMA according to ASTM E1545-11 (2016) with a heating rate of 5°C / min and the inflection point was measured.

[0039] In a preferred embodiment, the block copolymer has a number average molecular weight of at least 20,000 g / mol, preferably at least 30,000 g / mol and / or at most 300,000 g / mol, preferably at most 200,000 g / mol.

[0040] In a preferred embodiment, the rubber composition comprises 10 to 95 phr of an elastomer, preferably a diene-based elastomer; 5 to 90 phr of a block copolymer; and 20 to 200 phr of a filler comprising one or more of at least one silica and at least one carbon black. Thus, the (only) elastomer block of the block copolymer is considered herein as part of a total of 100 parts by weight of rubber / elastomer.

[0041] In a preferred embodiment, the filler comprises primarily silica, and optionally a silane coupling agent.

[0042] In a preferred embodiment, the rubber composition comprises 100 phr of elastomer; 5 phr to 90 phr (preferably 10 phr to 50 phr) of block copolymer; and 20 phr to 200 phr of filler comprising one or more of at least one silica and at least one carbon black (wherein the block copolymer and / or elastomeric blocks thereof are not calculated as part of the 100 parts by weight of rubber / elastomer).

[0043] In a preferred embodiment, the rubber composition comprises from 10 phr to 50 phr of the block copolymer; and from 50 phr to 90 phr of the elastomer.

[0044] The rubber composition may contain at least one and / or at least one additional diene-based rubber. Representative synthetic polymers are butadiene and its homologues and derivatives, such as homopolymerization products of methylbutadiene, dimethylbutadiene and pentadiene, and copolymers, such as those formed from butadiene or its homologues or derivatives with other unsaturated monomers. Among the latter are acetylenes, such as vinylacetylene, olefins, such as isobutylene, which copolymerizes with isoprene to form butyl rubber; vinyl compounds, such as acrylic acid, acrylonitrile (which polymerizes with butadiene to form NBR), methacrylic acid and styrene, the latter compound being polymerized with butadiene to form SBR, as well as vinyl esters and various unsaturated aldehydes, ketones and ethers, such as acrolein, methylisopropenyl ketone and vinyl ethyl ether. Specific examples of synthetic rubbers include chloroprene rubber (polychloroprene), polybutadiene (including cis-1,4-polybutadiene), polyisoprene (including cis-1,4-polyisoprene), butyl rubber, halogenated butyl rubber such as chlorinated butyl rubber or brominated butyl rubber, styrene / isoprene / butadiene rubber, 1,3-butadiene or isoprene with monomers such as styrene, copolymers of acrylonitrile, and ethylene / propylene terpolymers, also known as ethylene / propylene / diene monomers (EPDM), and particularly ethylene / propylene / dicyclopentadiene terpolymers. Other examples of usable rubbers 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 are natural rubber, synthetic polyisoprene, polybutadiene and SBR.

[0045] In one aspect, the elastomer is preferably at least two of the diene-based elastomers. For example, a combination of two or more elastomers is 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.

[0046] In one embodiment, an emulsion polymerization-derived styrene / butadiene (ESBR) having a relatively conventional styrene content of 20 to 28% bound styrene can be used, or for some applications, an ESBR having a medium to relatively high bound styrene content, i.e., 30 to 45% bound styrene content can be used. ESBR prepared by emulsion polymerization refers to copolymerization of styrene and 1,3-butadiene as an aqueous emulsion. This is well known to those skilled in the art. The bound styrene content can vary, for example, from 5% to 50%. In one aspect, ESBR may also contain acrylonitrile to form a terpolymer rubber, such as ESBAR, in an amount of, for example, 2 to 30 wt% bound acrylonitrile in the terpolymer. Styrene / butadiene / acrylonitrile copolymer rubber containing 2 to 40 wt% bound acrylonitrile in the copolymer prepared by emulsion polymerization is also considered to be a diene-based rubber for use in the present invention.

[0047] In another embodiment, SBR (SSBR) prepared by solution polymerization can be used. Such SSBR can, for example, have a combined styrene content of 5 to 50%, preferably 9 to 36%. SSBR can be conveniently 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 organic lithium compound as an initiator.

[0048] In one embodiment, cis-1,4-polybutadiene rubber (BR) is used. Suitable polybutadiene rubbers can be prepared, for example, by organic solution polymerization of 1,3-butadiene. BR can be conveniently characterized, for example, by having at least 90% cis-1,4-content and a glass transition temperature Tg of -95 to -105°C. Suitable polybutadiene rubbers are commercially available, for example, Budene® 1207, Budene® 1208, or Budene® 1223 from The Goodyear Tire & Rubber Company. In addition to Budene® 1223, these high cis-1,4-polybutadiene rubbers can be synthesized, for example, using a nickel catalyst system comprising a mixture of (1) an organic nickel compound, (2) an organic aluminum compound, and (3) a fluorine-containing compound, as described in U.S. Pat. No. 5,698,643 and U.S. Pat. No. 5,451,646.

[0049] In one embodiment, synthetic or natural polyisoprene rubber may be used.

[0050] The term "phr" as used herein, and according to conventional practice, means "parts by weight of each material per 100 parts by weight of rubber or elastomer." Typically, using this convention, a rubber composition contains 100 parts by weight of rubber / elastomer. The claimed composition may contain other rubbers / elastomers in addition to those explicitly mentioned in the claims, provided that the phr value of the claimed rubber / elastomer is consistent with the claimed phr range and the amount of all rubbers / elastomers in the composition results in a total of 100 parts of rubber. In one example, the composition may further include 1-10 phr, optionally 1-5 phr of one or more additional diene-based rubbers, such as SBR, SSBR, ESBR, PBD / BR, NR and / or synthetic polyisoprene. In another example, the composition may include less than 5 phr, preferably less than 3 phr of additional diene-based rubber, or may also be substantially free of such additional diene-based rubber. Unless otherwise indicated, the terms "rubber" and "composition" are used interchangeably herein.

[0051] The rubber composition may also include up to 70phr of processing oil. Processing oil may be included in the rubber composition as an extender oil commonly used to fill elastomers. Processing oil may also be included in the rubber composition by directly adding oil during rubber compounding. The processing oil used may include both the extender oil present in the elastomer and the process oil (process oil) added during compounding. Suitable process oils include various oils known in the art, including aromatic oils, paraffinic oils, naphthenic oils, vegetable oils and low PCA oils, such as MES, TDAE, SRAE and heavy naphthenic oils. Suitable low PCA oils include those having a polycyclic aromatic content of less than 3% by weight determined by the IP346 method. The procedure of the IP346 method can be found in Standard Methods for Analysis & Testing of Petroleum and Related Products and British Standard 2000 Parts, 2003, the 62nd edition, the Institute of Petroleum, United Kingdom publishes.

[0052] In a preferred embodiment, the rubber composition comprises 40 to 160 phr of silica.

[0053] Common siliceous pigments that can be used for rubber compounds include conventional pyrolysis and precipitation siliceous pigments (silicon dioxide). In one embodiment, precipitated silica is used. The conventional siliceous pigments used in the present invention are precipitated silica, such as those obtained by acidification of soluble silicates, such as sodium silicate. Such conventional silica can be characterized, for example, by having a BET surface area as measured using nitrogen. In one embodiment, the BET surface area can be 40 to 600 square meters per gram. In another embodiment, the BET surface area can be 80 to 300 square meters per gram. The BET method for measuring surface area is described in Journal of the American Chemical Society, Vol. 60, p. 304 (1930). Conventional silica can also be characterized by having a dibutyl phthalate (DBP) absorption value of 100 to 400, or 150 to 300. Various commercially available silicas may be used, such as those available from PPG Industries under the Hi-Sil trademark with the names 210, 315G and EZ160G; silicas available from Solvay with names such as Z1165MP and Premium 200MP and silicas available from Evonik AG with names such as VN2 and Ultrasil 6000GR and 9100GR.

[0054] Conventional carbon black can be used as conventional filler, with 10 to 150phr amount use.In another embodiment, 20 to 80phr carbon black can be used.Representative examples of this type of carbon black include 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 carbon blacks have iodine absorption of 9 to 145 g / kg and 34 to 150 cm 3 / 100 g of DBP value.

[0055] In addition, other fillers can be used in the rubber composition, including but not limited to particulate fillers, including ultra-high molecular weight polyethylene (UHMWPE), cross-linked particulate polymer gels, including but not limited to those disclosed in U.S. Pat. Nos. 6,242,534; 6,207,757; 6,133,364; 6,372,857; 5,395,891; or 6,127,488, and plasticized starch composite fillers, including but not limited to those disclosed in U.S. Pat. No. 5,672,639. The amount of these other fillers can be 1 to 30 phr.

[0056] In one embodiment, the rubber composition may contain a conventional sulfur-containing organosilicon compound.

[0057] Examples of suitable sulfur-containing organosilicon compounds have the formula:

[0058]

[0059] Where Z is selected from

[0060]

[0061] Where R 1 is an alkyl group of 1 to 4 carbon atoms, a cyclohexyl group or a phenyl group; R 2 is an alkoxy group of 1 to 8 carbon atoms or a cycloalkoxy group of 5 to 8 carbon atoms; Alk is a divalent hydrocarbon of 1 to 18 carbon atoms, and n is an integer of 2 to 8.

[0062] In one embodiment, the sulfur-containing organosilicon compound is 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 can be

[0063]

[0064] Where R 2 is an alkoxy group having 2 to 4 carbon atoms, or 2 carbon atoms; Alk is a divalent hydrocarbon having 2 to 4 carbon atoms, or 3 carbon atoms; and n is an integer of 2 to 5, or 2 or 4.

[0065] In another embodiment, suitable sulfur-containing organosilicon compounds include compounds disclosed in U.S. Pat. No. 6,608,125. In one embodiment, the sulfur-containing organosilicon compound includes 3-(octanoylthio)-1-propyltriethoxysilane, CH 3 (CH 2 ) 6 C(=O)-S-CH2 CH 2 CH 2 Si(OCH 2 CH 3 ) 3 , which is NXT TM Commercially available from Momentive Performance Materials.

[0066] In another embodiment, suitable sulfur-containing organosilicon compounds include those disclosed in US Patent Publication No. 2003 / 0130535. In one embodiment, the sulfur-containing organosilicon compound is Si-363 from Degussa.

[0067] The amount of sulfur-containing organosilicon compound in the rubber composition will vary depending on the levels of other additives used. Generally, the amount of the compound will be from 0.5 to 20 phr. In one embodiment, the amount will be from 1 to 10 phr.

[0068] It is easy for a person skilled in the art to understand that the rubber composition (or in other words the sulfur-vulcanized rubber composition) will be compounded by a method generally known in the field of rubber compounding, for example, various sulfur-vulcanizable component rubbers are mixed with various common additive materials, such as the common additive materials such as sulfur donors, curing aids such as activators and scorch retarders and processing additives such as oleoresins including tackifying resins and plasticizers, fillers, pigments, fatty acids, zinc oxide, waxes, antioxidants and antiozonants and peptizers. As known to those skilled in the art, according to the intended use of sulfur-vulcanizable and sulfur-vulcanized materials (rubbers), the above-mentioned additives are selected and usually used in conventional amounts. Representative examples of sulfur donors include elemental sulfur (free sulfur), disulfide amines, polymerized polysulfides and sulfur olefin adducts. In one embodiment, the sulfur-vulcanizing agent is elemental sulfur. The amount of the sulfur-vulcanizing agent can be 0.5 to 8 phr, or 1.5 to 6 phr. The typical amount of tackifying resin, if used, includes 0.5 to 10 phr, usually 1 to 5 phr. Typical amounts of processing aids include 1 to 50 phr. Typical amounts of antioxidants include 1 to 5 phr. Representative antioxidants can be, for example, diphenyl-p-phenylenediamine and others, such as those disclosed in The VanderbiltRubber Handbook (1978), pages 344-346. Typical amounts of antiozonants include 1 to 5 phr. Typical amounts of fatty acids (which can include stearic acid), if used, include 0.5 to 3 phr. Typical amounts of waxes include 1 to 5 phr. Microcrystalline wax is commonly used. Typical amounts of peptizers include 0.1 to 1 phr. Typical peptizers can be, for example, pentachlorothiophenol and dibenzamidodiphenyl disulfide.

[0069] In another embodiment, the composition comprises 5 phr to 80 phr of at least one resin, such as a traction resin. The resin may be selected from one or more of styrene-alpha methyl styrene resins, coumarone-indene resins, petroleum resins, hydrocarbon resins, terpene polymers, terpene phenol resins, phenol resins, C5 resins, C9 resins, CPD resins, DCPD resins, rosin-derived resins, and copolymers thereof. In addition, one or more of these resins may be hydrogenated.

[0070] Accelerators can be used to control the time and / or temperature required for vulcanization, and improve the properties of vulcanized rubber. In one embodiment, a single accelerator system, i.e., a primary accelerator, can be used. The total amount of one or more primary accelerators can be 0.5 to 10 or 0.5 or 4 phr, or 0.8 to 1.5 phr. In another embodiment, a combination of a primary accelerator and an auxiliary accelerator can be used, wherein the auxiliary accelerator is used in a smaller amount, such as 0.05 to 3 phr, to activate and improve the properties of the vulcanized rubber. The combination of these accelerators can be expected to produce a synergistic effect on the final properties, and is better to a certain extent than those produced by using any accelerator alone. In addition, a delayed-acting accelerator can be used, which is not affected by the normal processing temperature, but produces satisfactory solidification at ordinary vulcanization temperatures. Vulcanization scorch retarder can also be used. Suitable types of accelerators that can be used for the present invention are amines, disulfides, guanidines, thioureas, thiazoles, thiurams, sulfenamides, dithiocarbamates and xanthates / salts. In one embodiment, the primary accelerator is a sulfenamide. If a secondary accelerator is used, the secondary accelerator may be a guanidine, dithiocarbamate or thiuram compound. Suitable guanidines include diphenylguanidine and the like. Suitable thiurams include tetramethylthiuram disulfide, tetraethylthiuram disulfide and tetrabenzylthiuram disulfide.

[0071] The mixing of the rubber composition can be accomplished by methods known to those skilled in the art of rubber mixing. For example, the ingredients are usually mixed in at least two stages, i.e., at least one non-productive stage, followed by a productive mixing stage. The final curing agent (curatives) including the sulfur-vulcanizing agent is usually mixed in the final stage, which is usually referred to as the "productive" mixing stage, wherein the mixing is usually carried out at a temperature or final temperature lower than one or more mixing temperatures of the previous one or more non-productive mixing stages. The rubber composition can be subjected to a thermomechanical mixing step. The thermomechanical mixing step usually includes a period of time in a mixer or extruder suitable for mechanical processing to produce a rubber temperature of 140°C to 190°C. The suitable duration of the thermomechanical processing varies with the operating conditions and the volume and properties of the parts. For example, the thermomechanical processing can be 1 to 20 minutes.

[0072] In another aspect of the present invention, an article is provided, which may be preferably selected from tires, power transmission belts, hoses, tracks, air sleeves and conveyor belts. The article comprises the rubber composition according to one or more of the above embodiments or elements thereof.

[0073] In one embodiment, the tire comprises at least one component made of the rubber composition, wherein the component is at least one of the following: carcass ply, belt ply, band ply, apex, sidewall, tread, chip reinforcement layer, bead core, inner liner, bead core, ply strip, shoulder, undertread, tread cap and tread base. In principle, the composition can be used in a plurality of the tire components.

[0074] In another embodiment, the components are selected from at least one of the following: carcass plies, belt plies, apex, sidewall, chipper, flipper, chafer, and shoulder. In other words, the rubber composition may be of particular interest in components requiring high stiffness. In this specific embodiment, the tread or portions thereof are of no interest.

[0075] The tire, in particular the pneumatic tire, can be a racing tire, a passenger car tire, an aircraft tire, an agricultural tire, a bulldozer tire, an off-road tire, a truck tire, etc. In one embodiment, the tire is a passenger car or truck tire. The tire can also be a radial or bias tire.

[0076] The vulcanization of the rubber composition or (pneumatic) tire can be carried out generally at conventional temperatures of 100° C. to 200° C. In one embodiment, the vulcanization is carried out at a temperature of 110° C. to 180° C. Any conventional vulcanization method can 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, which are known and will be apparent to those skilled in the art.

[0077] In another aspect, the invention relates to the block copolymer itself, as described in the above aspects and optionally in the corresponding embodiments. In one embodiment, the block copolymer is a diblock copolymer.

[0078] In yet another aspect, the present invention relates to the use of the block copolymers described herein in one or more of a rubber composition, a rubber part, and a tire.

[0079] It should be emphasized that one or more embodiments or features thereof may be combined with one another within the scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0080] The structure, operation and advantages of the present invention will become more apparent when the following description is considered in conjunction with the accompanying drawings.Figure 1 A schematic cross section is shown through an exemplary tire. DETAILED DESCRIPTION

[0081] Figure 1 is a schematic cross section of a tire 1. The tire 1 has a tread 10, an inner liner 13, a belt structure including four belt plies 11, a carcass ply 9, two sidewalls 2 and two bead areas 3 including bead filler apexes 5 and beads 4. The exemplary tire 1 is suitable, for example, for mounting on a rim of a vehicle, such as a truck or a car. Figure 1 As shown in , the belt ply 11 may be covered by a cap ply 12. The carcass ply 9 includes a pair of axially opposite end portions 6, which are respectively bonded to each of the beads 4. Each axial end portion 6 of the carcass ply 9 may be turned up and wrapped around the respective beads 4 until a position to anchor each axial end portion 6. One or more of the carcass ply 9, the belt ply 11 and the cap ply 12 may have a plurality of substantially parallel reinforcements, which are made of a textile material, such as polyester, rayon or a similar suitable organic polymer compound, or made of metal wire. The turned-up portion 6 of the carcass ply 9 may join the axially outer surfaces of the two bead core wraps 8 and the axially inner surfaces of the two wheel reinforcement layers 7. As shown Figure 1 As shown in , an exemplary tread 10 may have four circumferential grooves, each groove defining a substantially U-shaped opening in the tread 10 .

[0082] although Figure 1 The embodiment proposes multiple tire components, including, for example, an apex rubber core 5, a heel reinforcement layer 7, a bead core wrap 8 and a cap layer 12, but these components are not mandatory for the present invention. The turn-up end of the carcass cord layer 9 is also not necessary for the present invention, or may pass on the opposite side of the bead area 3 and terminate at the axial inside of the bead 4 instead of the axial outside of the bead 4. The tire can also have, for example, more or less than 4 grooves. It should be emphasized that the present invention focuses on a rubber composition comprising a block copolymer. Therefore, Figure 1 The description of the invention and its components are to be understood as examples only and not to limit the invention.

[0083] In one embodiment of the invention, a rubber composition, such as in a rubber component of tire 1, comprises a solution-polymerized styrene-butadiene rubber and a block copolymer having an elastomer block and a poly(isobornyl methacrylate) block. In an alternative embodiment, the rubber composition may comprise one or more of polybutadiene, natural rubber, solution-polymerized styrene-butadiene as an elastomer. Instead of the poly(isobornyl methacrylate) block, the block copolymer may also comprise a poly(adamantyl methacrylate) block or a thermoplastic material, i.e., a block of both (isobornyl methacrylate) units and (adamantyl methacrylate) units within the thermoplastic block.

[0084] Such block copolymers can be prepared by one skilled in the art by, for example, free radical, ionic, coordination, reversible addition-fragmentation chain transfer (RAFT) or atom transfer radical (ATRP) polymerization. Example

[0085] The invention is illustrated by the following examples. Unless expressly stated otherwise, parts and percentages are given by weight.

[0086] In one embodiment, isobornyl methacrylate (IBOMA) is polymerized to PIBOMA via RAFT polymerization at a temperature of 60°C using 1,1,2-trichloroethane (TCA) as a solvent and by adding 4-cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl]pentanoic acid (CDTPA) and α,α'-azoisobutyronitrile (AIBN) in a SDTPA:AIBN molar ratio of 4:1, wherein IBOMA is present at 1.44 g / ml or 50%, for 24 hours. After obtaining the thermoplastic PIBOMA (block), styrene and butadiene monomers are added with the addition of CDTPA and initiators 2,2'-azobis(N-butyl-2-methylpropionamide) (VAM-110) and 1,1,2-trichloroethane (1,1,2-TCA), with an exemplary reaction time of 72 hours and a molar ratio of TCA to initiator of 1:1, all reactions being carried out at a temperature of 115° C. It is emphasized again that this synthesis of PIBOMA-SBR block copolymers constitutes only one possible example using polymerization techniques known to those skilled in the art.

[0087] In another embodiment, the block copolymer can be synthesized by anionic polymerization, wherein the first elastomer block is synthesized from an elastomer-forming monomer in a first step, and then a thermoplastic monomer is added in a second step to form a second thermoplastic block of the diblock copolymer. For example, butadiene is distilled under vacuum into a pressure-stabilized glass reactor precooled at -20°C. In addition, the reactor is filled with an inert atmosphere of up to 0.1 bar overpressure. A cyclohexane solution of tetraacetylethylenediamine (TMEDA) is provided in a separate flask and degassed. The solution is injected into a reactor containing butadiene under an overpressure of an inert atmosphere (e.g., Ar) at -20°C. The reactor is then heated to 55°C and the solution is stirred at this temperature for 20 minutes. A hexane solution of n-BuLi is injected into the reactor at 55°C, resulting in the formation of poly(butadienyl)lithium (PBD-Li+). Once the injection of n-BuLi is completed, the temperature in the reactor is raised to 60°C. The polymerization of butadiene is carried out at 60°C for 1 hour, at which time the temperature is reduced to 45°C. The temperature is further reduced to 25°C and 1,1-diphenylethylene (DPE) is injected into the reactor to terminate the polybutadiene anion. Stirring is continued at 25°C for 15 minutes, wherein the color of the solution changes from light yellow to orange-red. The solution is then cooled to 0°C and tetrahydrofuran (THF) is introduced into the reactor, causing the color of the solution to change to red. Finally, IBOMA is injected into the reactor at 0°C, causing the color of the solution to disappear. The polymerization of IBOMA is carried out at 0°C for 1.5 hours, at which time the polymerization is quenched by injecting deoxygenated anhydrous methanol. The resulting block copolymer can be purified by precipitation (twice) into excess methanol and dried.

[0088] The present inventors have synthesized a variety of different block copolymers comprising blocks having different molecular weights and different elastomeric monomer units, and included those in the rubber compositions shown in Table 1 below.

[0089] In particular, Table 1 shows two control samples of rubber compositions comprising SSBR, filler (here carbon black), oil, stearic acid, antioxidant, wax, zinc oxide, sulfur and a curing accelerator. Control sample 1 does not contain a thermoplastic polymer and is reinforced primarily by its carbon black filler, while control sample 2 (which is also not according to the invention) contains 10 phr of polyethylene (PE) for additional reinforcement of the rubber composition.

[0090] Each of the present invention examples 1-7 includes different types of block copolymers according to embodiments of the present invention. None of the present invention examples include PE. Carbon black, oil, stearic acid, antioxidants, waxes, zinc oxide, sulfur, and accelerators are included at the same weight level as control samples 1 and 2. In addition, the present invention examples include SSBR of the same type as the control samples, but the amount thereof varies slightly in view of the chain length of the elastomer block of the block copolymer used. The composition of each of the block copolymers 1-7 is shown in the footnote of Table 1 below.

[0091] Table 1

[0092]

[0093] a Sprintan TM SLR 3402-SCHKOPAU, solution-styrene-butadiene rubber, glass transition temperature is about -62°C;

[0094] b A block copolymer comprising a SSBR block having an Mn of 28700 g / mol and a PIBOMA block having an Mn of 26000 g / mol, wherein the PIBOMA block corresponds to 10 phr; SSBR microstructure: 20 wt% styrene, 17 wt% 1,2-butadiene, 63 wt% 1,4-butadiene; polydispersity 1.6;

[0095] c A block copolymer comprising a SSBR block having an Mn of 26,600 g / mol and a PIBOMA block having an Mn of 36,700 g / mol, wherein the PIBOMA block corresponds to 10 phr; SSBR microstructure: 18.5 wt% styrene, 16.5 wt% 1,2-butadiene, 65 wt% 1,4-butadiene; polydispersity 1.5;

[0096] d A block copolymer comprising a SSBR block having an Mn of 25900 g / mol and a PIBOMA block having an Mn of 46500 g / mol, wherein the PIBOMA block corresponds to 10 phr; SSBR microstructure: 15 wt% styrene, 17 wt% 1,2-butadiene, 68 wt% 1,4-butadiene; polydispersity 1.5;

[0097] eA block copolymer comprising a SSBR block having an Mn of 11800 g / mol and a PIBOMA block having an Mn of 40200 g / mol, wherein the PIBOMA block corresponds to 10 phr; SSBR microstructure: 15 wt% styrene, 15 wt% 1,2-butadiene, 70 wt% 1,4-butadiene; polydispersity 1.8;

[0098] f A block copolymer comprising a BR block having an Mn of 78400 g / mol and a PIBOMA block having an Mn of 26800 g / mol, wherein the PIBOMA block corresponds to 10 phr; BR microstructure: 47 wt% 1,2-butadiene, 53 wt% 1,4-butadiene; polydispersity 1.25;

[0099] g A block copolymer comprising a BR block having an Mn of 68500 g / mol and a PIBOMA block having an Mn of 36700 g / mol, wherein the PIBOMA block corresponds to 10 phr; BR microstructure: 52 wt% 1,2-butadiene, 48 wt% 1,4-butadiene; polydispersity 1.16;

[0100] h A block copolymer comprising a BR block having an Mn of 80230 g / mol and a PIBOMA block having an Mn of 66550 g / mol, wherein the PIBOMA block corresponds to 10 phr; BR microstructure: 51 wt% 1,2-butadiene, 49 wt% 1,4-butadiene; polydispersity 1.33;

[0101] i an ultra high molecular weight polyethylene having a number average molecular weight Mn of 4,700,000 g / mol determined by the Margolies equation;

[0102] j TDAE oil;

[0103] k Such as phenylenediamine:

[0104] l Sulfenamide and diphenylguanidine.

[0105] Table 2 shows the storage modulus (E') measurements for the compositions also listed in Table 1, wherein the storage modulus can be considered an indicator of stiffness, or in other words, of the reinforcing effect of the PE and the different block copolymers in the above compositions.

[0106] Control Sample 2, which contains additional PE reinforcement, shows increased stiffness values ​​below 100° C. At higher temperatures, the reinforcement of PE drops significantly and is even lower than the value of Control Sample 1, although Control Sample 2 contains the same amount of carbon black as Control Sample 1. According to the inventors' unconstrained theory, this is mainly caused by the melting point of the PE material (at 135° C.).

[0107] Turning to the inventive examples, all inventive examples show significantly higher stiffness than control samples 1 and 2 at the measuring temperatures of 30°C, 50°C and 100°C. Even at 150°C, the stiffness of all inventive examples is higher compared to control sample 2. While inventive examples 1, 2, 3, 4 and 7 also show higher storage modulus values ​​at 150°C compared to control sample 1, the storage modulus values ​​of inventive examples 5 and 6 are at least at a comparable level compared to control sample 1 at the same temperature. However, in this context, it is emphasized that the stiffness and reinforcement of inventive examples 5 and 6 at lower temperatures are significantly higher compared to control sample 1.

[0108]

[0109] Table 2

[0110] * Dynamic Mechanical Thermal Analysis (DMTA) was performed according to ASTM D7028-07. The cured (vulcanized) compounds were measured on strips (length × width × thickness = 20 × 6 × 2 (mm)) using a DMA 242C model (Netzsch, Germany) operated in tensile mode (strain between 0.05 and 0.07%, pretension: 10-2 N). The experiments were performed at a frequency of 1 Hz with a heating rate of 2 °C / min from -180 °C to 180 °C.

Claims

1. A rubber composition comprising an elastomer, a filler and a block copolymer, wherein the block copolymer comprises an elastomer block and a thermoplastic block, wherein the elastomer block is composed of at least one diene-based elastomer, and the thermoplastic block is composed of a polyalkyl acrylate, wherein the polyalkyl acrylate comprises a single-bonded oxygen atom, wherein the alkyl acrylate comprises a polycyclic substituent on its single-bonded oxygen atom, wherein the block copolymer is a diblock copolymer, wherein the rubber composition comprises 50 to 90 phr of the elastomer; 10 to 50 phr of the block copolymer; 20 to 200 phr of the filler, wherein the elastomer comprises at least one diene-based elastomer, wherein the polyalkyl acrylate has the following structure: wherein n represents the number of alkyl acrylate monomers in the polyalkyl acrylate, wherein n is an integer greater than 10 and less than 2000; wherein R1 represents an alkyl group; wherein R2 represents a polycyclic hydrocarbon substituent.

2. The rubber composition according to claim 1, wherein the diene-based elastomer is selected from one or more of styrene-butadiene rubber, polybutadiene, natural rubber, synthetic polyisoprene rubber and isoprene-butadiene rubber.

3. The rubber composition according to claim 1, wherein the elastomer or the elastomer block has a functional group for coupling to the surface of one of silica and carbon black.

4. The rubber composition of claim 3, wherein the elastomer block comprises an elastomer chain having a first chain end and a second chain end, wherein the first chain end is connected to the polyalkylacrylate block, and wherein the functional group is located at the second chain end.

5. The rubber composition according to claim 1, wherein the alkyl group is -CH3 or -C2H5.

6. The rubber composition according to claim 1, wherein the alkyl acrylate has one of the following on its single-bonded oxygen atom: i) a bicyclic substituent, ii) a tricyclic substituent, iii) a hydrocarbon substituent comprising at least seven carbon atoms, at least five of which are arranged in a ring.

7. The rubber composition of claim 1, wherein the polyalkyl acrylate is one of poly(isobornyl methacrylate) and poly(adamantyl methacrylate).

8. The rubber composition according to claim 1, wherein the polyalkyl acrylate comprises one or more of the following structures:

9. The rubber composition of claim 1, wherein the thermoplastic block is composed of polyalkyl acrylate and has one or more of: i) a number average molecular weight Mn of at least 10,000 g / mol; and ii) at least 10 monomers of alkyl acrylate.

10. The rubber composition of claim 1, wherein the thermoplastic block is composed of polyalkyl acrylate and has one or more of: i) a number average molecular weight Mn of up to 150,000 g / mol; and ii) up to 2000 monomers of alkyl acrylate.

11. The rubber composition of claim 1, wherein the elastomeric block has one or more of: (i) a number average molecular weight, Mn, of at least 10,000 g / mol; and (ii) at least 90 monomers selected from styrene, butadiene, and isoprene.

12. The rubber composition of claim 1, wherein the elastomeric block has one or more of: (i) a number average molecular weight, Mn, of up to 150,000 g / mol; and (ii) up to 2000 monomers selected from styrene, butadiene, and isoprene.

13. The rubber composition of claim 1, wherein the block copolymer has a first glass transition temperature in the range of -92°C to -15°C and a second glass transition temperature in the range of 150°C to 250°C.

14. The rubber composition according to claim 1, wherein the ratio of the number average molecular weight Mn of (i) the elastomeric block to the number average molecular weight Mn of (ii) the thermoplastic block is in the range of 0.1 to 0.

95.

15. The rubber composition of claim 1, wherein the filler comprises one or more of: at least one silica and at least one carbon black.

16. An article selected from the group consisting of a tire, a hose, a track, an air sleeve and a conveyor belt, wherein the article comprises the rubber composition according to any one of the preceding claims 1 to 15.

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