Epoxy-modified liquid cis-butadiene synergistically modified wood lignin tread rubber composition and its mixing method

Abstract

The present application relates to the technical field of tire rubber manufacturing, and discloses a tread rubber composition of epoxy modified liquid cis-butadiene and synergistically modified lignin and a mixing method thereof. The present application effectively improves the comprehensive performance of the tread rubber, effectively improves the wet grip, wear resistance and bio-based content of the rubber, and reduces the compression heat generation, abrasion and cost of the rubber through the synergistic effect of epoxy modified liquid cis-butadiene, surface modified lignin (obtained by complex modification of lignin by gamma-glycidyl ether oxygen propyl trimethoxysilane and polyethylene glycol monomethyl ether) and lignin masterbatch (obtained by mixing surface modified lignin, solution polymerized styrene-butadiene rubber and epoxy modified liquid cis-butadiene).

Description

Technical Field

[0001] This invention relates to the field of tire rubber manufacturing technology, and more specifically, to a tread rubber composition of epoxy-modified liquid cis-butadiene synergistically modified lignin and its mixing method. Background Technology

[0002] Tire heat generation is a core factor affecting driving safety and energy consumption. Excessive dynamic heat generation of tread materials can lead to increased rolling resistance (increased fuel consumption), accelerated thermal and oxygen aging (shortened lifespan), and in extreme cases, the risk of tread delamination. Driven by the "energy conservation and carbon reduction" policy, low heat generation has become the core objective of tread material research and development, while also considering high wet grip (safety in rainy weather), high wear resistance (lifespan), and low cost (industrial feasibility).

[0003] In existing SSBR / NR / BR tread systems, low heat generation usually relies on reducing the amount of filler or using softeners, but this leads to a decrease in abrasion resistance. Although highly dispersed silica can improve wet skid resistance and abrasion resistance, its surface hydroxyl groups are dense, resulting in high friction with the rubber interface and thus high dynamic heat generation. Although traditional liquid butadiene rubber (LBR) can reduce heat generation, it weakens the rubber-filler interface bonding, leading to a sharp drop in abrasion resistance.

[0004] Lignin is a natural aromatic polymer with a three-dimensional network structure found in plants. It is a biopolymer formed by three phenylpropane units linked together by ether and carbon-carbon bonds. It contains abundant aromatic ring structures, aliphatic and aromatic hydroxyl groups, and quinone groups, and is mainly found in the secondary layer of plant cell walls. As a green and renewable resource, lignin has many advantages, including wide availability, light weight, high bioefficiency, and broad ecological adaptability. Industrial lignin mainly comes from black liquor in the paper industry and residues from biorefining industries. If not fully utilized, it will become waste, seriously polluting the environment.

[0005] Most polymers, such as plastics and rubbers, require fillers to improve their performance and reduce costs. Driven by environmental protection and resource sustainability, an increasing number of researchers are turning their attention to lignin, a green and renewable biomass resource. Lignin possesses excellent mechanical properties, biodegradability, and thermal stability. However, the large number of aliphatic and aromatic hydroxyl groups in its structure results in high polarity, while commonly used natural rubber, styrene-butadiene rubber, cis-butadiene rubber, and ethylene-propylene rubber are all non-polar rubbers. This difference leads to poor compatibility between lignin as a filler and the rubber matrix, making it prone to agglomeration and stress concentration points, resulting in a sharp drop in the interfacial friction coefficient. Simultaneously, due to the high rigidity of lignin molecular chains, its addition causes a surge in dynamic heat generation in the rubber compound, increasing rolling resistance. Furthermore, the weak interfacial interaction between lignin and silica prevents the formation of an effective reinforcing network, leading to decreased wear resistance and limiting its large-scale application in tire treads.

[0006] Chinese invention patent 202311790137.7 describes a modified lignin obtained through esterification with lignin, a certain proportion of end-capping agent acetic acid, and long-chain fatty acid oleic acid. The modified lignin is then mixed with rubber and granulated to obtain a fully bio-based, highly filled lignin rubber masterbatch. The modified lignin improves the compatibility between lignin and natural rubber, facilitating lignin dispersion in the rubber matrix. Furthermore, the resulting highly filled lignin rubber masterbatch exhibits high surface hydrophobicity, allowing it to replace traditional reinforcing agents like carbon black with better reinforcing effects. However, it still fails to resolve the balance issue between "interfacial bonding strength and dynamic slippage capability"; a weak interface results in insufficient reinforcement, while an overly strong interface leads to increased heat generation. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides an epoxy-modified liquid butadiene synergistic lignin-modified tread rubber composition and its mixing method.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: A tread rubber composition of epoxy-modified liquid butadiene synergistically modified lignin, wherein the rubber composition is prepared by mixing raw materials comprising the following components based on 100 parts by weight of raw rubber: 57-65 parts by weight of solution-polymerized styrene-butadiene rubber 20-35 parts by weight of natural rubber 2-10 parts by weight of butadiene rubber Epoxy-modified liquid butadiene rubber (LBR-EP) 5-15 parts by weight, 35-55 parts by weight of highly dispersed silica 2.0-5.0 parts by weight of silane coupling agent. 5-15 parts by weight of surface-modified lignin. 5-15 parts by weight of lignin masterbatch; The raw rubber is the sum of solution-polymerized styrene-butadiene rubber, natural rubber, cis-butadiene rubber, and epoxy-modified liquid cis-butadiene rubber; The surface-modified lignin is obtained by composite modification of lignin with γ-glycidyl etheroxypropyltrimethoxysilane and polyethylene glycol monomethyl ether; The lignin masterbatch is prepared by mixing surface-modified lignin, solution-polymerized styrene-butadiene rubber, and epoxy-modified liquid cis-butadiene rubber.

[0009] Preferably, the rubber composition is prepared by mixing raw materials comprising the following components based on 100 parts by weight of raw rubber: 58-62 parts by weight of solution-polymerized styrene-butadiene rubber 25-30 parts by weight of natural rubber 3-10 parts by weight of butadiene rubber 5-10 parts by weight of epoxy-modified liquid butadiene rubber 40-50 parts by weight of highly dispersed silica 2.0-5.0 parts by weight of silane coupling agent. 5-12 parts by weight of surface-modified lignin 5-13 parts by weight of lignin masterbatch Vulcanizing agent 1.0-3.0 parts by weight, Accelerator 1.0-4.0 parts by weight, Anti-aging agent 1.0-4.0 parts by weight, 1.0-5.0 parts by weight of plasticizer. Activator 0.8-5.0 parts by weight.

[0010] Preferably, the solution-polymerized styrene-butadiene rubber has a styrene content of 20-30% and a vinyl content of 35-45%.

[0011] Preferably, the epoxy-modified liquid butadiene rubber has a number average molecular weight of 2000-3000 and an epoxy value of 0.3-0.5 eq / 100g.

[0012] Preferably, the preparation of the surface-modified lignin includes the following steps: lignin powder is vacuum-dried and then added to a high-speed mixer, followed by the sequential addition of modifier γ-glycidyl etheroxypropyltrimethoxysilane (KH-560) and polyethylene glycol monomethyl ether. Modification is carried out at 110-120℃ and 1800-2200 r / min for 35-45 min, followed by cooling and pulverization for later use. More preferably, the vacuum drying temperature is 75-85℃, and the drying time is 3.5-4.5 h. The lignin powder has a particle size of 2-5 μm.

[0013] Preferably, the total amount of the modifier is 5%-7% of the lignin content; more preferably, the amount of γ-glycidoxypropyltrimethoxysilane is 3%-4% of the lignin content, and the amount of polyethylene glycol monomethyl ether is 2%-3% of the lignin content. Further, the mass ratio of γ-glycidoxypropyltrimethoxysilane to polyethylene glycol monomethyl ether is (1.5-2.0):1.

[0014] Preferably, the preparation of the lignin masterbatch includes the following steps: adding surface-modified lignin, solution-polymerized styrene-butadiene rubber, and epoxy-modified liquid cis-butadiene rubber into a mixer, mixing at 120-130℃ and 70-80 r / min for 6-8 min, pressing into sheets, and cooling for later use. More preferably, the sheet thickness is 2-3 mm.

[0015] Preferably, the mass ratio of the surface-modified lignin, solution-polymerized styrene-butadiene rubber, and epoxy-modified liquid cis-butadiene rubber is 1:(2-3):0.5.

[0016] Preferably, the butadiene rubber is nickel-based butadiene rubber.

[0017] Preferably, the highly dispersed silica has a specific surface area (CTAB) of 220-240 m². 2 / g, DBP oil absorption value 2.1-2.3cm 3 / g, dispersibility ≥92%.

[0018] Preferably, the activator includes zinc oxide and stearic acid, wherein the zinc oxide is 2.5-3.5 parts by weight and the stearic acid is 0.8-1.2 parts by weight.

[0019] Furthermore, the present invention also provides a method for mixing the rubber composition, comprising the following steps: 1) First stage mixing: Add solution-polymerized styrene-butadiene rubber, natural rubber, and butadiene rubber to a mixer and masticate at 85-95℃ and 55-65 r / min for 3-4 min; add highly dispersed silica, surface-modified lignin, and silane coupling agent, and mix at 95-105℃ for 5-6 min; then add epoxy-modified liquid butadiene rubber and other chemical auxiliaries (except for lignin masterbatch, vulcanizing agent, and accelerator), heat to 135-145℃ and mix for 7-9 min, discharge the rubber to obtain the first stage compound, discharge temperature ≤150℃, and let stand for 6-8 hours to cool to room temperature; 2) Two-stage mixing: Add the first-stage compound and lignin masterbatch to the open mill and pass through it 4-6 times at 55-65℃; add vulcanizing agent and accelerator, mix for 4-5 minutes, and control the temperature of the compound to ≤70℃ to obtain the final compound.

[0020] Preferably, the final rubber compound is vulcanized at 155-165°C and 18-22 MPa for “T90+1min”; T90 is measured using the final rubber compound.

[0021] The present invention adopts the above-mentioned scheme, and through the synergistic effect of LBR-EP, surface modified lignin and lignin masterbatch, it effectively improves the comprehensive performance of tread compound, effectively improves wet grip, abrasion resistance and bio-based content of the compound, and reduces compression heat generation, abrasion and cost of the compound. Detailed Implementation

[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present invention.

[0023] The rubber composition of this embodiment is obtained by combining fillers, vulcanizing agents, and other auxiliary materials with a rubber component formed from solution-polymerized styrene-butadiene rubber (SSBR) and other conjugated diene rubbers.

[0024] (Rubber composition) Examples of conjugated diene rubbers used as rubber components include natural rubber (NR), polyisoprene rubber (IR), polybutadiene rubber (BR), styrene-butadiene rubber (SBR), styrene-isoprene copolymer rubber, butadiene-isoprene copolymer rubber, or styrene-isoprene-butadiene copolymer rubber, and various diene rubbers commonly used in tire tread rubber compositions. These conjugated diene rubbers can be used alone or in blends of two or more.

[0025] In embodiments of the present invention, blends of solution-polymerized styrene-butadiene rubber (SSBR) and other conjugated diene rubbers are preferred, especially blends of natural rubber (NR), butadiene rubber (BR) and solution-polymerized styrene-butadiene rubber (SSBR) as part of the rubber base. In the present invention, epoxy-modified liquid butadiene rubber is also incorporated.

[0026] (Silicon dioxide) Silica refers to silica-silicic acid based filler materials, and not just silica in the narrow sense. It can be appropriately selected from existing materials used as reinforcing fillers. Examples include wet silica (hydrated silica) and dry silica (anhydrous silica). In the embodiments of this invention, highly dispersed silica is preferred.

[0027] CTAB of silica is preferably 220m. 2CTAB concentrations above a certain level (g) and not below the lower limit tend to provide good reinforcing effects, resulting in excellent properties including tensile strength and abrasion resistance. CTAB concentrations of silica with a g content of 240 μg or higher are also preferred. 2 Below a certain value ( / g), CTAB levels not exceeding the upper limit tend to result in good dispersibility. Furthermore, the CTAB content of silica is determined according to ISO 5794-1:2006.

[0028] (Silane coupling agent) When the above-mentioned rubber composition contains silica, it preferably further contains a silane coupling agent. There are no particular limitations on the silane coupling agent; commonly used silane coupling agents can be used. Examples include silane coupling agents based on sulfides, polysulfides, thioesters, thiols, olefins, epoxy groups, amino groups, and alkyl groups. These can be used alone or in combination of two or more. Among these, sulfide-based silane coupling agents and amino-based silane coupling agents are preferred.

[0029] Examples of silane coupling agents for the aforementioned sulfide systems include bis(3-triethoxysilylpropyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(3-methyldimethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(3-triethoxysilylpropyl)disulfide, bis(3-trimethoxysilylpropyl)disulfide, bis(3-methyldimethoxysilylpropyl)disulfide, bis(2-triethoxysilylethyl)disulfide, bis(3-triethoxysilylpropyl)trisulfide, bis(3-triethoxysilylpropyl)trisulfide, bis(3-trimethoxysilylpropyl)trisulfide, and bis(3-methyldimethoxysilylpropyl)tetrasulfide. Bis(2-triethoxysilylethyl) trisulfide, bis(3-monoethoxydimethylsilylpropyl) tetrasulfide, bis(3-monoethoxydimethylsilylpropyl) trisulfide, bis(3-monoethoxydimethylsilylpropyl) disulfide, bis(3-monoethoxydimethylsilylpropyl) tetrasulfide, bis(3-monoethoxydimethylsilylpropyl) trisulfide, bis(3-monoethoxydimethylsilylpropyl) disulfide, bis(2-monoethoxydimethylsilylethyl) tetrasulfide, bis(2-monoethoxydimethylsilylethyl) trisulfide, bis(2-monoethoxydimethylsilylethyl) disulfide, etc.

[0030] Examples of silane coupling agents in the aforementioned thioester system include 3-hexanoylthiopropyltriethoxysilane, 3-octanoylthiopropyltriethoxysilane, 3-decanoylthiopropyltriethoxysilane, 3-lauroylthiopropyltriethoxysilane, 2-hexanoylthioethyltriethoxysilane, 2-octanoylthioethyltriethoxysilane, 2-decanoylthioethyltriethoxysilane, and 2-lauroylthio... Ethyltriethoxysilane, 3-hexanoylthiopropyltrimethoxysilane, 3-octanoylthiopropyltrimethoxysilane, 3-decanoylthiopropyltrimethoxysilane, 3-lauroylthiopropyltrimethoxysilane, 2-hexanoylthioethyltrimethoxysilane, 2-octanoylthioethyltrimethoxysilane, 2-decanoylthioethyltrimethoxysilane, 2-lauroylthioethyltrimethoxysilane, etc.

[0031] Examples of thiol-based silane coupling agents include 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, γ-mercaptopropylethoxybis(propane-hexaethoxy-siloxane), and 3-octanoylthio-1-propyltriethoxysilane.

[0032] Examples of olefin-based silane coupling agents include dimethoxymethylvinylsilane, vinyltrimethoxysilane, dimethylethoxyvinylsilane, diethoxymethylvinylsilane, triethoxyvinylsilane, vinyltris(2-methoxyethoxy)silane, allyltrimethoxysilane, allyltriethoxysilane, p-styryltrimethoxysilane, 3-(methoxydimethoxydimethylsilyl)propyl acrylate, 3-(trimethoxysilyl)propyl acrylate, 3-[dimethoxy(methyl)silyl]propyl methacrylate, 3-(trimethoxysilyl)propyl methacrylate, 3-[dimethoxy(methyl)silyl]propyl methacrylate, 3-[triethoxysilyl]propyl methacrylate, and 3-[tris(trimethylsiloxy)silyl]propyl methacrylate.

[0033] Examples of epoxy-based silane coupling agents include 3-epoxypropoxypropyl(dimethoxy)methylsilane, 3-epoxypropoxypropyltrimethoxysilane, diethoxy(3-epoxypropoxypropyl)methylsilane, triethoxy(3-epoxypropoxypropyl)silane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane.

[0034] Examples of amino-based silane coupling agents include N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-ethoxysilyl-N-(1,3-dimethylbutylene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, and N-(vinylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane.

[0035] In the embodiments of the present invention, one or more of bis(3-triethoxysilylpropyl)tetrasulfide (Si-69), 3-mercaptopropyltrimethoxysilane (Si-75), and 3-octanoylthio-1-propyltriethoxysilane (NXT) are preferred, and the proportion is not particularly limited, with 3-mercaptopropyltrimethoxysilane (Si-75) being particularly preferred.

[0036] The content of the silane coupling agent relative to 100 parts by weight of silica is preferably 3 parts by weight or more, more preferably 5 parts by weight or more. Amounts of 3 parts by weight or more tend to provide an additive effect. This amount is also preferably 20 parts by weight or less, more preferably 15 parts by weight or less. Amounts not exceeding 20 parts by weight tend to produce an effect comparable to the amount added, and tend to achieve good processability during mixing.

[0037] (Modified lignin) Surface-modified lignin is prepared by modifying lignin with a composite modifier; the composite modifier is γ-glycidoxypropyltrimethoxysilane and polyethylene glycol monomethyl ether. Lignin can form π-π conjugation with the highly polar segments of solution-polymerized styrene-butadiene rubber (SBR). γ-glycidoxypropyltrimethoxysilane provides epoxy groups, and polyethylene glycol monomethyl ether reduces the surface polarity of lignin, improving compatibility, thereby constructing a dynamic cross-linking interface. The lignin used is sulfate lignin powder with a particle size of 2-6 μm; the amount of composite modifier is 5%-7% of the lignin mass, preferably 3%-4% of the lignin mass for γ-glycidoxypropyltrimethoxysilane and 2%-3% of the lignin mass for polyethylene glycol monomethyl ether.

[0038] The masterbatch lignin is prepared by mixing surface-modified lignin, solution-polymerized styrene-butadiene rubber, and epoxy-modified liquid cis-butadiene rubber.

[0039] (Activator) There are no particular limitations on the activator used; commonly used activators can be used. Zinc oxide and stearic acid are typically used together as activators. Commonly used zinc oxides include indirect zinc oxide, active zinc oxide, and nano zinc oxide. Indirect zinc oxide is commonly used, but its dispersibility is poor, requiring a higher dosage. Active zinc oxide is evenly distributed in the rubber compound, has a large contact area with hydrogen sulfide, and a greater chance of interfacial reaction. Furthermore, the active substances in active zinc oxide products provide a co-catalytic effect, resulting in a high conversion rate of zinc oxide to zinc sulfide. Therefore, active zinc oxide is an excellent vulcanizing activator, and its dosage can be appropriately reduced compared to indirect zinc oxide. Nano zinc oxide particles have a diameter in the range of 10-80 nm, a large specific surface area, and exhibit three effects: interfacial interaction, small size, and quantum tunneling. It has high activity and can effectively reduce the amount of zinc oxide used. Commercially available stearic acid can be used as the stearic acid.

[0040] (Vulcanizing agent) There are no particular restrictions on the type of vulcanizing agent; commonly used vulcanizing agents can be used. Examples of vulcanizing agents include sulfur and sulfur derivatives, organic peroxides, and resin-based vulcanizing agents.

[0041] Examples of sulfur and sulfur derivatives mentioned above include sulfur powder, insoluble sulfur, tetramethylthiuram disulfide, diethylthiuram disulfide, dibenzothiazole disulfide, N-cyclohexyl-2-benzothiazole sulfenamide, 2-mercaptobenzothiazole, tetraethylthiuram disulfide, tetramethylthiuram monosulfide, dibenzyl disulfide, dipentamethylenethiuram tetrasulfide, alkylphenol sulfides, etc.

[0042] Examples of the aforementioned organic peroxides include dicumyl peroxide, di-tert-butyl peroxide, benzoyl peroxide, tert-butyl peroxide benzoate, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, 1,1-bis(tert-butylperoxy)cyclohexane, lauroyl peroxide, cyclohexanone peroxide, tert-butyl hydroperoxide, di-di-tert-butyl hydroperoxide, propylphenyl hydroperoxide, cyclohexanone peroxide, and 1,4-bis-tert-butylperoxyisopropylbenzene.

[0043] Examples of resin-based vulcanizing agents include p-tert-butylphenol formaldehyde resin, p-tert-octylphenol formaldehyde resin, alkylphenol formaldehyde resin, phenol formaldehyde resin, brominated p-tert-butylphenol formaldehyde resin, hexamethoxymethyl melamine resin, epoxy resin, phenolic epoxy resin, cashew nut phenolic resin, resorcinol formaldehyde resin, bismaleimide resin (BMI), urea-formaldehyde resin, furfural resin, and o-cresol formaldehyde epoxy resin.

[0044] These vulcanizing agents can be used alone or in combination of two or more. Sulfur powder and insoluble sulfur are preferred.

[0045] (Vulcanization accelerator) There are no particular restrictions on the type of accelerator; commonly used vulcanization accelerators can be used. Examples include sulfenamide, thiazole, thiuram, thiourea, guanidine, dithiocarbamate, aldehyde-amine, or aldehyde-amine accelerators. These can be used alone or in combination of two or more.

[0046] Examples of sulfonamide compounds include N-cyclohexyl-2-benzothiazolyl sulfonamide, N-tert-butyl-2-benzothiazolyl sulfonamide, N,N-dicyclohexyl-2-benzothiazolyl sulfonamide, N-oxodiethylidene-2-benzothiazolyl sulfonamide, and N,N-diisopropyl-2-benzothiazolyl sulfonamide.

[0047] Examples of the aforementioned thiazole series include 2-mercaptobenzothiazole, dibenzothiazole disulfide, zinc salt of 2-mercaptobenzothiazole, N-cyclohexyl-2-benzothiazole sulfenamide, N-tert-butyl-2-benzothiazole sulfenamide, N-oxodiethylene-2-benzothiazole sulfenamide, derivatives of dibenzothiazole disulfide, sodium salt of 2-thiol-benzothiazole, and 2-benzothiazole disulfide.

[0048] Examples of the aforementioned thiuram series include tetramethylthiuram disulfide, tetramethylthiuram monosulfide, tetraethylthiuram disulfide, tetraisobutylthiuram disulfide, tetrabenzylthiuram disulfide, dipentylthiuram disulfide, bis(1,5-pentylene)thiuram tetrasulfide, bispentamethylenethiuram hexasulfide, tetra(2-ethylhexyl)thiuram disulfide, and bispentamethylenethiuram monosulfide.

[0049] Examples of guanidine compounds mentioned above include diphenylguanidine, di-o-toluidine, triphenylguanidine, o-toluidine, and diphenylguanidine phthalate.

[0050] Examples of dithiocarbamate compounds include zinc ethylphenyl dithiocarbamate, zinc butylphenyl dithiocarbamate, sodium dimethyl dithiocarbamate, zinc dimethyl dithiocarbamate, zinc diethyl dithiocarbamate, zinc dibutyl dithiocarbamate, zinc dipentyl dithiocarbamate, zinc dipropyl dithiocarbamate, a coordination salt of zinc pentamethylene dithiocarbamate and piperidine, zinc hexadecyl isopropyl dithiocarbamate, zinc octadecyl isopropyl dithiocarbamate, zinc dibenzyl dithiocarbamate, sodium diethyl dithiocarbamate, piperidine pentamethylene dithiocarbamate, selenium dimethyl dithiocarbamate, tellurium diethyl dithiocarbamate, cadmium dipentyl dithiocarbamate, etc.

[0051] Examples of aldehyde-amine or aldehyde-amine compounds mentioned above include acetaldehyde-aniline reactants, butyraldehyde-aniline condensates, hexamethylenetetramine, and acetaldehyde-amine reactants.

[0052] These accelerators can be used alone or in combination of two or more. N-cyclohexyl-2-benzothiazole sulfenamide (CZ) and dibenzothiazole disulfide (DM) are preferred.

[0053] (Anti-aging agents) There are no particular limitations on antioxidants; commonly used antioxidants can be used. Examples include amines, phenols, and heterocyclic antioxidants. They can be used alone or in combination of two or more.

[0054] Examples of amine antioxidants include N-phenyl-N'-isopropyl-p-phenylenediamine, N-1,3-dimethylbutyl-N'-phenyl-p-phenylenediamine, 4,4'-bis(α,α-dimethylbenzyl)diphenylamine, N-cyclohexyl-N'-phenyl-p-phenylenediamine, and N-(1-methylheptyl)-N'-phenyl-p-phenylenediamine.

[0055] Examples of phenolic antioxidants include 2,6-di-tert-butyl-4-methylphenol, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and tris[2,4-di-tert-butylphenyl] phosphite.

[0056] Examples of heterocyclic antioxidants include 2-mercaptobenzimidazole, zinc salt of 2-mercaptobenzimidazole, 2,2,4-trimethyl-1,2-dihydroquinoline polymer, 2-(2-hydroxyphenyl)benzimidazole, and 2,2,4-trimethyl-1,2-dihydroquinoline polymer (RD).

[0057] These antioxidants can be used alone or in combination of two or more. N-1,3-dimethylbutyl-N'-phenyl-p-phenylenediamine (antioxidant 4020) is preferred.

[0058] (Softener) Softeners are mainly classified into three categories: petroleum-based, vegetable oil-based, and ester-based, with petroleum-based being the most commonly used. Petroleum-based softeners include processing oils and petroleum resins. Processing oils typically include aromatic oils, naphthenic oils, and paraffin oils, while petroleum resins usually refer specifically to low-softening-point petroleum resins. Vegetable oil-based softeners are derived from natural raw materials, are environmentally friendly, and have a low odor; common varieties include pine tar, tall oil, castor oil, and soybean oil. Ester-based softeners are typically used for high-performance tire treads and generally include phthalates, adipates, and polyesters. Phthalate esters include dioctyl phthalate and dibutyl phthalate; adipates include dioctyl adipate; and polyesters include polypropylene adipate. In this embodiment, rapeseed oil is preferred. Example

[0059] The formulations of the examples and comparative examples are shown in Table 1.

[0060] Table 1

[0061] The sources of raw materials are as follows: 1. Solution polystyrene-butadiene rubber (SSBR), 7260, Dushanzi Petrochemical Company solution polystyrene-butadiene rubber, styrene content 26%, vinyl content 40%, Mooney viscosity ML (1+4) 100℃=60-70.

[0062] 2. Natural rubber (NR), SCR5, Hainan Natural Rubber Industry Group, Mooney viscosity ML (1+4) 100℃=65-75.

[0063] 3. Nickel-based butadiene rubber (BR), BR 9100, Sinopec Group, Mooney viscosity ML (1+4) 100℃=48-58.

[0064] 4. Highly dispersed silica, VN3, Evonik Chemicals, specific surface area 220-240 m² 2 / g, DBP oil absorption value 2.1-2.3cm 3 / g, dispersibility ≥92%.

[0065] 5. Silane coupling agent, Si75, Evonik Chemical.

[0066] 6. Surface-modified lignin, with a mass ratio of KH-560 to polyethylene glycol monomethyl ether of 1.5:1. KH-560, from Shanghai Kanglang Biotechnology Co., Ltd., chemically named γ-glycidyl etheroxypropyltrimethoxysilane. Sulfate lignin, from Shandong Ailiwan Chemical Co., Ltd., with a particle size of 2-6 μm.

[0067] 7. The mass ratio of masterbatch lignin, surface dynamically modified lignin, SSBR and LBR-EP is 1:2.5:0.5.

[0068] 8. Vulcanizing agent, insoluble sulfur IS-60, Shandong Huachen Chemical.

[0069] 9. Accelerator CZ, chemical name N-cyclohexyl-2-benzothiazole sulfenamide, Shandong Shangshun Chemical Co., Ltd.

[0070] 10. Accelerator DM, chemical name dibenzothiazole disulfide, Shandong Shangshun Chemical Co., Ltd.

[0071] 11. Antioxidant 4020, chemical name N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, manufactured by Sheng'ao Chemical Technology Co., Ltd.

[0072] 12. Bio-based rapeseed oil, Shandong Tengbo Chemical Technology Co., Ltd.

[0073] 13. Nano zinc oxide, Shijiazhuang Zhiyi Zinc Industry Co., Ltd.

[0074] 14. Plant-derived stearic acid, Qingdao Shengying Innovation Materials Co., Ltd.

[0075] <Preparation of Surface-Modified Lignin> Sulfate lignin powder was vacuum dried at 80℃ for 4 hours and then added to a high-speed mixer. KH-560 and polyethylene glycol monomethyl ether (KH-560: polyethylene glycol monomethyl ether = 1.5:1) were then added sequentially. KH-560 accounted for 3% of the lignin mass, and polyethylene glycol monomethyl ether accounted for 2% of the lignin mass. The mixture was modified at 115℃ and 1800 r / min for 35 min to graft epoxy groups and lipophilic segments onto the lignin surface. After cooling, the mixture was pulverized for later use.

[0076] Lignin Masterbatch Surface-modified lignin, SSBR, and LBR-EP were added to an internal mixer at a mass ratio of 1:2.5:0.5 and mixed at 125℃ and 80r / min for 7 minutes. During this process, the lubricity and reactivity of LBR-EP were utilized to ensure that the lignin was evenly dispersed and formed a preliminary bond with SSBR, resulting in a stable and dispersed masterbatch. The masterbatch was then pressed into tablets (2-3mm thick) and cooled for later use.

[0077] Example 1: In a rubber matrix of solution-polymerized styrene-butadiene rubber, 45 parts by weight of highly dispersed silica, 9 parts by weight of surface-modified wood, and 8 parts by weight of lignin masterbatch were blended, and the total amount of fillers (highly dispersed silica, surface-modified wood, and lignin masterbatch) was 62 parts by weight.

[0078] Example 2: In a rubber matrix of solution-polymerized styrene-butadiene rubber, 43 parts by weight of highly dispersed silica, 10 parts by weight of surface-modified wood, and 9 parts by weight of lignin masterbatch were blended, and the total amount of fillers (highly dispersed silica, surface-modified wood, and lignin masterbatch) was 62 parts by weight.

[0079] Example 3: In a rubber matrix of solution-polymerized styrene-butadiene rubber, 40 parts by weight of highly dispersed silica, 12 parts by weight of surface-modified wood, and 13 parts by weight of lignin masterbatch were blended, and the total amount of fillers (highly dispersed silica, surface-modified wood, and lignin masterbatch) was 65 parts by weight.

[0080] The difference between Comparative Example 1 and Example 1 is that Comparative Example 1 did not add LBR-EP (epoxy modified liquid cis-butadiene rubber), and the amount of solution-polymerized styrene-butadiene rubber added was 63 parts by weight.

[0081] The main difference between Comparative Example 2 and Example 1 is that LBR is used instead of LBR-EP.

[0082] The main difference between Comparative Example 3 and Example 1 is that no lignin masterbatch was added.

[0083] The main difference between Comparative Example 4 and Example 1 is that no surface-modified lignin was added.

[0084] The main difference between Comparative Example 5 and Example 1 is that a low proportion of solution-polymerized styrene-butadiene rubber (SBR) was used as the rubber matrix, and the amount of SBR blended was 55.5 parts by weight.

[0085] <Mixing Method> The mixing methods for the examples and comparative examples are as follows: 1) First stage mixing: Add solution-polymerized styrene-butadiene rubber, natural rubber, and butadiene rubber to a mixer and masticate at 85-95℃ and 55-65 r / min for 3-4 min; add highly dispersed silica, surface-modified lignin, and silane coupling agent, and mix at 95-105℃ for 5-6 min; then add epoxy-modified liquid butadiene rubber and other chemical auxiliaries (except for lignin masterbatch, vulcanizing agent, and accelerator), heat to 135-145℃ and mix for 7-9 min, discharge the rubber to obtain the first stage compound, discharge temperature ≤150℃, and let stand for 6-8 hours to cool to room temperature; 2) Two-stage mixing: Add the first-stage compound and lignin masterbatch to the open mill and pass through it 4-6 times at 55-65℃; add vulcanizing agent and accelerator, mix for 4-5 minutes, and control the temperature of the compound to ≤70℃ to obtain the final compound.

[0086] <Testing Methods> 1. Dynamic heat generation: GB / T 1687.3-2016 (compression heat generation, 60℃, 1.82MPa).

[0087] 2. Dynamic mechanical properties: DMA test (-60~80℃, frequency 10Hz, 60℃ tanδ reflects heat generation, 0℃ tanδ reflects slip resistance) 3. Wet friction coefficient: GB / T 3903.6-2005 (tile surface wetted with water, load 100N).

[0088] 4. Abrasion resistance: GB / T 1689-2014 (Akron abrasion resistance).

[0089] 5. Cost: Calculated based on the market price of raw materials in 2025 (highly dispersed silica 16 yuan / kg, modified lignin 3.5 yuan / kg, LBR-EP 10 yuan / kg).

[0090] The test results are shown in Table 2.

[0091] Table 2

[0092] As can be seen from Tables 1 and 2, the overall performance of the embodiment is more balanced compared to the comparative example.

[0093] Comparative Example 1 (without LBR-EP) and Example 1 show that LBR-EP effectively improves the overall performance of the rubber composition, improving compression heat generation, rolling resistance, wet skid resistance, and abrasion resistance, thus enhancing economic benefits. Comparative Examples 2 and 4 show that LBR-EP is more effective than LBR. Comparative Examples 1-4 and Example 1 show that LBR-EP, surface-modified lignin, and lignin masterbatch can synergistically bond to construct a dense reinforcing network, effectively improving compression heat generation, rolling resistance, wet skid resistance, and abrasion resistance, thus enhancing economic benefits. Example 1 and Comparative Example 5 (low SSBR ratio) show that Comparative Example 5 (low SSBR ratio) has inferior overall performance compared to Example 1 due to insufficient polar segments, proving that a high SSBR ratio is the foundation for achieving performance advantages. Furthermore, Example 3 has a lower cost (11,400 yuan / ton) than the comparative examples (11,500-11,800 yuan / ton), with increased bio-based content, achieving a triple breakthrough in performance, environmental protection, and cost.

[0094] The foregoing description of embodiments of the present invention, through which those skilled in the art are able to implement or use the present invention, will be readily apparent to those skilled in the art. Various modifications to these embodiments will be readily apparent to those skilled in the art. The general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novelty disclosed herein.

Claims

1. A tread rubber composition of epoxy-modified liquid cis-butadiene synergistically modified lignin, characterized in that, The rubber composition is prepared by mixing raw materials comprising the following components based on 100 parts by weight of raw rubber: 57-65 parts by weight of solution-polymerized styrene-butadiene rubber 20-35 parts by weight of natural rubber 2-10 parts by weight of butadiene rubber 5-15 parts by weight of epoxy-modified liquid butadiene rubber 35-55 parts by weight of highly dispersed silica 2.0-5.0 parts by weight of silane coupling agent. 5-15 parts by weight of surface-modified lignin 5-15 parts by weight of lignin masterbatch; The raw rubber is the sum of solution-polymerized styrene-butadiene rubber, natural rubber, cis-butadiene rubber, and epoxy-modified liquid cis-butadiene rubber; The surface-modified lignin is obtained by composite modification of lignin with γ-glycidyl etheroxypropyltrimethoxysilane and polyethylene glycol monomethyl ether; The lignin masterbatch is prepared by mixing surface-modified lignin, solution-polymerized styrene-butadiene rubber, and epoxy-modified liquid cis-butadiene rubber.

2. The tread rubber composition of epoxy-modified liquid cis-butadiene synergistic modification of lignin according to claim 1, characterized in that, The rubber composition is prepared by mixing raw materials comprising the following components based on 100 parts by weight of raw rubber: 58-62 parts by weight of solution-polymerized styrene-butadiene rubber 25-30 parts by weight of natural rubber 3-10 parts by weight of butadiene rubber 5-10 parts by weight of epoxy-modified liquid butadiene rubber 40-50 parts by weight of highly dispersed silica 2.0-5.0 parts by weight of silane coupling agent. 5-12 parts by weight of surface-modified lignin 5-13 parts by weight of lignin masterbatch Vulcanizing agent 1.0-3.0 parts by weight, Accelerator 1.0-4.0 parts by weight, Anti-aging agent 1.0-4.0 parts by weight, 1.0-5.0 parts by weight of plasticizer. Activator 0.8-5.0 parts by weight.

3. The tread rubber composition of epoxy-modified liquid cis-butadiene synergistic modification of lignin according to claim 1 or 2, characterized in that, The solution-polymerized styrene-butadiene rubber has a styrene content of 20-30% and a vinyl content of 35-45%.

4. A tread rubber composition for epoxy-modified liquid butadiene synergistic modification of lignin according to claim 1 or 2, characterized in that, The epoxy-modified liquid butadiene rubber has a number average molecular weight of 2000-3000 and an epoxy value of 0.3-0.5 eq / 100g.

5. A tread rubber composition for epoxy-modified liquid butadiene synergistic modification of lignin according to claim 1 or 2, characterized in that, The preparation of the surface-modified lignin includes the following steps: After vacuum drying, lignin powder is added to a high-speed mixer, followed by the addition of modifiers γ-glycidyl etheroxypropyltrimethoxysilane and polyethylene glycol monomethyl ether. The mixture is modified at 110-120℃ and 1800-2200 r / min for 35-45 min, then cooled and pulverized for later use. Preferably, the total amount of the modifier is 5%-7% of the lignin content; more preferably, the amount of γ-glycidyl etheroxypropyltrimethoxysilane is 3%-4% of the lignin content, and the amount of polyethylene glycol monomethyl ether is 2%-3% of the lignin content. Preferably, the mass ratio of the γ-glycidyl etheroxypropyltrimethoxysilane to polyethylene glycol monomethyl ether is (1.5-2.0):1; Preferably, the vacuum drying temperature is 75-85℃ and the drying time is 3.5-4.5h; Preferably, the lignin powder has a particle size of 2-5 μm.

6. A tread rubber composition for epoxy-modified liquid butadiene synergistic modification of lignin according to claim 1 or 2, characterized in that, The preparation of the lignin masterbatch includes the following steps: adding surface-modified lignin, solution-polymerized styrene-butadiene rubber, and epoxy-modified liquid cis-butadiene rubber into a mixer, mixing at 120-130℃ and 70-80 r / min for 6-8 min, and then pressing into sheets and cooling for later use. Preferably, the mass ratio of the surface-modified lignin, solution-polymerized styrene-butadiene rubber, and epoxy-modified liquid cis-butadiene rubber is 1:(2-3):0.5; Preferably, the thickness of the compressed tablet is 2-3 mm.

7. A tread rubber composition for epoxy-modified liquid butadiene synergistic modification of lignin according to claim 1 or 2, characterized in that, The cis-butadiene rubber mentioned is nickel-based cis-butadiene rubber; And / or, the specific surface area (CTAB) of the highly dispersed silica is 220-240 m². 2 / g, DBP oil absorption value 2.1-2.3cm 3 / g, dispersibility ≥92%; And / or, the activator comprises zinc oxide and stearic acid, wherein the zinc oxide is 2.5-3.5 parts by weight and the stearic acid is 0.8-1.2 parts by weight.

8. The method for mixing the rubber composition according to any one of claims 1-7, characterized in that, Includes the following steps: 1) First stage mixing: Add solution-polymerized styrene-butadiene rubber, natural rubber, and butadiene rubber to a mixer and masticate at 85-95℃ and 55-65 r / min for 3-4 min; add highly dispersed silica, surface-modified lignin, and silane coupling agent, and mix at 95-105℃ for 5-6 min; then add epoxy-modified liquid butadiene rubber and other chemical auxiliaries (except for lignin masterbatch, vulcanizing agent, and accelerator), heat to 135-145℃ and mix for 7-9 min, discharge the rubber to obtain the first stage compound, discharge temperature ≤150℃, and let stand for 6-8 hours to cool to room temperature; 2) Two-stage mixing: Add the first-stage compound and lignin masterbatch to the open mill and pass through it 4-6 times at 55-65℃; add vulcanizing agent and accelerator, mix for 4-5 minutes, and control the temperature of the compound to ≤70℃ to obtain the final compound.

9. The method for mixing the rubber composition according to claim 8, characterized in that, The final rubber compound is vulcanized at 155-165℃ and 18-22MPa at a rate of "T90+1min"; T90 is measured using the final rubber compound.

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