Vehicle tire composition containing rice husk ash silica

Abstract

The present invention relates to a vehicle tire composition, a method for manufacturing the same, and a vehicle tire manufactured from the composition. The composition contains rice husk ash silica as a reinforcing agent and lignin sulfonate as a stiffness enhancer. The present invention also relates to the use of rice husk ash silica in a vehicle tire composition containing lignin sulfonate.

Description

Technology Field

[0001] The present invention relates to a vehicle tire composition, a method for manufacturing the same, and a vehicle tire manufactured from the composition. The composition contains rice husk ash silica as a reinforcing filler and lignin sulfonate as a stiffness enhancer. The present invention also relates to the use of rice husk ash silica in a vehicle tire composition containing lignin sulfonate. Background Technology

[0002] Reinforcing fillers have long been used in tires to improve the mechanical properties of the tire composition. Traditionally, fillers included carbon black, chalk, talc, kaolin, bentonite, titanium dioxide, and silica. Silica has been identified as particularly advantageous for lowering rolling resistance and improving grip, especially on wet surfaces. Silica derived from sand is traditionally used.

[0003] Over the past few years, the tire industry has strived to improve environmental sustainability in all aspects. One of the main goals was to use more environmentally sustainable raw materials, particularly those obtainable from renewable resources. In this regard, silica obtained from rice husk ash (referred to herein as "RHA silica") has been used in tire compositions.

[0004] In an attempt to improve sustainability, other materials proposed for use in the tire industry include lignin and lignin derivatives such as lignin sulfonates. Lignin is a highly cross-linked polymer formed from phenolic compounds that constitute the major structural components in the cell walls of various plants, particularly wood and bark. Lignin is generally a byproduct of the papermaking process, as it must be removed from wood pulp during the process. However, it can be recovered through other processes. The processes used in its manufacture produce different types of lignin materials. Common recovery processes, such as the sulfite pulping process, form water-soluble lignosulfonates containing sulfonated lignin polymers. These may be referred to as "lignin sulfonates," "lignosulfonates," or "sulfite lignin." These materials possess good mechanical, physicochemical, and biodegradable properties as well as excellent thermal stability, and have been proposed for use to improve the dispersibility of reinforcing agents, such as carbon black, in tire compositions.

[0005] There is a continuous demand to improve the sustainability of tires, and the objective of the present invention is to achieve this without adversely affecting the performance characteristics of the tires.

[0006] The inventors surprisingly discovered that when RHA silica is used instead of sand silica in a vehicle tire composition containing lignin sulfonate, the efficacy of lignin sulfonate as a stiffness enhancer is improved.

[0007] Due to its natural origin, RHA silica may contain trace amounts of metal derived from soil or fertilizers used during rice cultivation. Without being bound by theory, the inventors consider that a higher metal content present in RHA silica, for example, potassium ions, interacts with lignin sulfonate to increase the compatibility between RHA silica and lignin sulfonate compared to the compatibility between sand silica and lignin sulfonate.

[0008] According to a first embodiment, the present invention relates to a tire composition for a vehicle comprising: 100 phr of a rubber component; 50 to 160 phr of silica obtained from rice husk ash; and 2 to 25 phr of lignin sulfonate.

[0009] According to a second embodiment, the present invention relates to a vehicle tire comprising a vehicle tire composition according to a first embodiment.

[0010] According to a third embodiment, the present invention relates to a method for manufacturing a vehicle tire composition according to a first embodiment, wherein the method comprises the steps of: introducing a silica filler and a lignin sulfonate into a rubber component to produce a vulcanizable rubber compound; and heating the vulcanizable rubber compound at a predetermined temperature and for a predetermined time to vulcanize it; and wherein the silica filler is obtained from rice husk ash.

[0011] According to a fourth embodiment, the present invention relates to the use of rice husk ash silica in a vehicle tire composition, wherein the vehicle tire composition comprises 100 phr of rubber components and 2 to 25 phr of lignin sulfonate.

[0012] According to the fifth aspect, the present invention relates to the use of silica derived from rice husk ash in a vehicle tire composition containing lignin sulfonate to improve the stiffness enhancement of lignin sulfonate. Specific details for implementing the invention

[0013] The present invention relates to a tire composition for vehicles comprising 100 phr of a rubber component. By convention, "phr" is 1 part per 100 parts of the rubber component. "Rubber component" means a component that is rubber in the composition. As used herein, the term "rubber" is intended to include natural rubber and synthetic rubber. The terms "rubber" and "elastomer" are used interchangeably unless otherwise specified.

[0014] Any known rubber component or blend of rubber components may be used in the vehicle tire composition according to the present invention, and a person skilled in the art can easily select a suitable rubber or rubber blend in consideration of the intended use of the composition. Non-limiting examples of rubber suitable for use in the composition are well known to a person skilled in the art and include natural rubber (NR), synthetic polyisoprene rubber, styrene-isoprene rubber, styrene-butadiene rubber, styrene-isoprene-butadiene rubber, butadiene-isoprene rubber, polybutadiene, butyl rubber, neoprene, acrylonitrile-butadiene rubber (NBR), silicone rubber, fluoroelastomer, ethylene acrylic rubber, ethylene-propylene rubber, ethylene-propylene terpolymer (EPDM), ethylene vinyl acetate copolymer, epichlorohydrin rubber, chlorinated polyethylene-propylene rubber, chlorosulfonated polyethylene rubber, hydrogenated nitrile rubber, and tetrafluoroethylene-propylene rubber. The ratio of any rubber blend can be selected as needed, for example, based on the viscoelastic properties of the tire composition. Those skilled in the art can easily determine the elastomer and its relative amounts that may be suitable for providing the desired range of viscoelastic properties.

[0015] In one embodiment, the rubber component contains repeating units derived from butadiene. Examples of such rubber include, but not limited to, styrene-butadiene rubber (SBR) and butadiene rubber (BR). In one embodiment, the rubber for use in the present invention is SBR, which generally refers to any synthetic rubber produced by the polymerization of styrene and butadiene monomers, i.e., any styrene-butadiene copolymer. SBR is commonly used in the tire industry and can be produced by well-known methods, such as copolymerization of the corresponding monomers in an emulsion, suspension, or solution. The styrene and butadiene monomers may be selected in suitable ratios depending on the intended use and properties of the rubber compound.

[0016] In one embodiment, the rubber component comprises styrene butadiene rubber (SBR), natural rubber (NR), butadiene rubber (BR), or any combination thereof. In one embodiment, the rubber component comprises or consists of solution-polymerized styrene butadiene rubber (SSBR) and natural rubber (NR). The rubber component may comprise 40 to 80 phr of SSBR and 20 to 60 phr of NR, preferably 50 to 70 phr of SSBR and 30 to 50 phr of NR, for example, about 60 phr of SSBR and about 40 phr of NR.

[0017] NR is a natural product that can be advantageously included to improve the sustainability characteristics of a tire composition. Additionally, when RHA silica is used instead of sand silica in rubber compounds with high NR loading, the inventors consider that the higher metal content in RHA silica compared to sand silica interacts with polar impurities present in NR, thereby increasing the compatibility between RHA silica and NR more than between sand silica and NR. This improves the dispersibility of silica, thereby improving the dispersion of uncured (evaluated as RPA) and cured (evaluated as the Payne effect) fillers compared to the corresponding compound with sand silica. Furthermore, in tire compositions, the dispersion of fillers evaluated in the form of a tan delta curve (tan delta 0°C / 60°C) may be better when RHA silica is used, and RR may also be improved as predicted by tan delta @ 60°C. Accordingly, in one embodiment, the rubber component comprises 35 to 90 phr, preferably 50 to 80 phr, or 60 to 70 phr of natural rubber.

[0018] A vehicle tire composition comprises silica obtained from rice husk ash, which refers to silica obtained from ash generated by incinerating rice husks. This is referred to herein as "rice husk ash silica" or "RHA silica."

[0019] The composition comprises 50 to 160 phr of RHA silica. In one embodiment, the composition comprises 50 to 120 phr of RHA silica, preferably 50 to 90 phr of RHA silica, for example 60 to 80 phr of RHA silica or 60 to 70 phr of RHA silica. Generally, the composition may comprise 50, 60, 70, or 80 phr of RHA silica up to 80, 90, 100, 110, 120, 130, 140, 150, or 160 phr of RHA silica, wherein any upper and lower limits may be combined.

[0020] Rice is one of the oldest crops in the world, cultivated in over 100 countries, and consumed as a staple food by more than half of the global population. The husk is the outer shell of the rice grain, and massive amounts of husk are generated as waste during the processing of rice for consumption. Because the husk has a hard surface, low nutritional value, high silicon content, and low bulk density, it is difficult to utilize efficiently. Furthermore, since the husk does not decompose easily, most of the husk produced worldwide is discarded in fields or incinerated, damaging the soil and causing environmental pollution. Currently, one of the most common disposal methods is incineration for power generation at thermal and gasification power plants, but this presents the problem of generating very large amounts of RHA. Therefore, using RHA silica in tires would be a desirable solution to these serious problems.

[0021] The rice husks were immediately burned and the literature [ Maejo Int. J. Sci. Technol. 2012 , 6Silica of various purity can be produced with or without using the pretreatment described in

[03] , 430-448. The transformation of raw rice husk into clean white, gray, or light gray ash varies significantly depending on the incineration temperature. At temperatures of 300 to 450°C, fresh rice husk is transformed only into carbonized rice husk, whereas temperatures of 500 to 650°C produce white or gray ash depending on the soaking time (the duration of incineration within the mentioned temperature range). Rice husk ash produced at temperatures of 500 to 650°C for an incineration holding (soaking) time of 2.5 to 6 hours is considered ideal for producing white amorphous silica, whereas crystallinity appears when the incineration temperature is increased above 700°C.

[0022] The production of rice husk ash by directly incinerating rice husks can be achieved by known methods, such as direct incineration in open air, muffle furnaces, fluidized bed combustion technology, or torpedo reactors (Indian technology). The fluidized bed process is a practical and flexible method for producing different grades of rice husk ash (RHA) and can induce higher levels of silica by inducing lower levels of ignition and carbon loss compared to other incineration conditions. In addition, hydrothermal synthesis methods have been used in conjunction with the incineration step in the production of rice husk ash.

[0023] The chemical composition of rice husk ash varies across different samples due to different regions, varieties, climates, soils, and fertilizers used during rice cultivation. The percentage of silica (SiO2) in the ash can vary, typically exceeding 80 or 90% and up to 99%, with the remainder being impurities including K2O; P2O5; CaO; SO3; MgO; Al2O3; Fe2O3; MnO; Rb2O; ZnO; CuO, and Na2O. The composition of rice husk ash according to geographical location is shown in Table 2 [ Maejo Int. J. Sci. Technol. 2012 , 6

[03] , 430-448] reported that the level of natural potassium oxide in rice husk ash can be 1.23 to 4.76%, i.e., in the range of 12,300 to 46,700 ppm. The impurity levels of both sand silica and RHA silica will vary depending on the manufacturing method, but generally, RHA silica has a higher metal content, particularly a higher potassium content, than sand silica.

[0024] The inventors have discovered that when silica generally has a high potassium content, aggregation of the silica may occur, which makes it difficult to disperse in the rubber component and ultimately leads to undesirable mechanical properties. Accordingly, in one embodiment, RHA silica is selected to have a potassium content of 500, 450, 400, or 350 ppm or less based on the silica. The silica may have a potassium content of 100, 150, 200, 250, or 300 ppm or more based on the silica. All references to the potassium content of any silica in this invention refer to the potassium ions (K) of said silica. + It is intended to refer to the ) content. Potassium content can be determined by inductively coupled plasma (ICP) - optical emission spectroscopy (OES) as described in the examples. In this method, silica is dispersed in water, and HCl is added to K in the solution + Generates ions. K + Ions are detected and measured.

[0025] Several methods for increasing the purity of RHA silica and reducing levels of metallic impurities, including potassium, are known in the art and generally involve pre-treating rice husks before incineration to produce rice husk ash. Various pre-treatment methods, including acid leaching, base pretreatment, and microbial pretreatment, have typically been used in combination with certain acids. In the case of acid leaching, different types of acids have been used, and HCl has proven effective in removing metallic impurities. Organic acids, including H2SO4, HNO3, and citric acid, acetic acid, or oxalic acid, may also be used. Alkalines such as NaOH and NH4OH can also be used to pre-treat rice husks, as with microbial fermentation, to reduce potassium levels. These methods are described in the literature [ Maejo Int. J. Sci. Technol. 2012 , 6 (03), 430-448], and literature[ Chemistry, Processing and Utilization, 2019

[207] is summarized, the full contents of which are incorporated herein by reference and can be used to produce RHA silica having a potassium content of less than 500 ppm.

[0026] When ash is ground from acid-leached rice husks, fine particles with a uniform particle size distribution, a larger surface area, and more micropores can be obtained. Acid leaching of rice husks is typically carried out before incineration to provide silica powder with a large specific surface area and excellent quality. After incineration, if potassium ions are present at high levels, the surface area decreases due to strong interactions between silica and potassium ions. This is why the potassium level in the present invention is preferably 500 ppm or less.

[0027] In addition, silica can be extracted from rice husk ash by precipitation. The process can be characterized by the extraction of silica gel using NaOH and the precipitation of silica using CO2. This is also [ Chemistry, Processing and Utilization,2019, As described in

[207] , it has the environmental advantage of being able to regenerate NaOH and CO2 using fresh calcium hydroxide. A similar process disclosed in European Patent No. 3770115, which is incorporated by reference, involves the steps of dissolving rice husk ash and an inorganic alkali such as NaOH in water to provide a slurry of silicate, separating the slurry into solid and liquid phases, and drying to provide silica.

[0028] In addition, the inventors have discovered that the weak coefficient (WK) of silica can also be an important indicator of good performance in a tire composition, and in one embodiment, the RHA silica has a weak coefficient of 20 or less, preferably 15 or less or 10 or less.

[0029] The coefficient of weakness, also known as WK, is measured by laser light scattering as described in the examples and is an indicator of silica dispersibility; it can be expressed as the ratio between larger aggregate sizes and smaller aggregate sizes. The higher the WK, the lower the dispersibility of silica and the larger the formed aggregates. When manufacturing high-performance rubber compounds with required mechanical properties, the dispersion of any reinforcing filler and filler-rubber interactions are key characteristics. Therefore, WK is relevant to performance characteristics.

[0030] RHA silica with a potassium content of 500 ppm or less and a weak factor of less than 20 is commercially available from various suppliers. An example of such a product is RHA silica sold under the trade name K160 by Wilmar.

[0031] Silica aggregation also has the effect of reducing the surface area of ​​the silica. Therefore, in one embodiment, the RHA silica is at least 100 m² 2 / g, preferably at least 120 m 2 / g, preferably at least 140 m 2It has a CTAB surface area of ​​ / g. The CTAB surface area is up to 220 m² 2 / g, preferably up to 200 m 2 / g, preferably up to 170 m 2 It may be / g. The CTAB surface area is measured according to ISO 5794-1G as described in the examples.

[0032] Automotive tire compositions also include lignin sulfonates. "Lignin sulfonate" refers to lignin containing at least one sulfonate moiety, i.e., a sulfonated derivative of lignin. As understood from the description, the term "sulfonate" refers to a salt or ester of a sulfonic acid. Lignin sulfonates can be produced, for example, during the sulfite pulping process of wood. During this process, lignin is extracted from wood chips and then sulfonated using hydrogen sulfite. The sulfonation process introduces sulfonic acid groups onto the lignin structure to produce a water-soluble polymer. However, other known manufacturing methods may be used to produce lignin sulfonates.

[0033] For use in the present invention, the lignin sulfonate may comprise one or more alkali metal salts or alkaline earth metal salts of lignin sulfonic acid. Specific examples of such salts include potassium salts, sodium salts, calcium salts, magnesium salts, lithium salts, and barium salts. One or more combinations of these salts may be used. Other salts include ammonium salts. In one embodiment, the lignin sulfonate for use in the present invention is provided in the form of a sodium salt.

[0034] Lignin sulfonates are commercially available in the form of, for example, calcium, sodium, ammonium, and magnesium lignosulfonates. An example of such a product is water-soluble sodium lignosulfonate supplied by Borregaard Lignotech under the trade name Borresperse NA. Borresperse NA is based on sodium lignosulfonate derived from a spruce wood sulfite solution and is supplied as a water-soluble powder.

[0035] The amount of lignin sulfonate to RHA silica can be selected according to the overall composition. In one embodiment, the ratio of lignin sulfonate to RHA silica is 0.01:1 to 0.5:1, preferably 0.02:1 to 0.5:1, for example, about 0.15:1.

[0036] In addition to RHA silica, lignin sulfonate, and rubber components, the automotive tire composition may include other components. Additional components may include additional polymers, processing aids (e.g., oils, waxes, resins, and plasticizers), curing systems (e.g., vulcanizing agents, vulcanization accelerators, and vulcanization accelerators), deterioration inhibitors (e.g., antioxidants or ozone inhibitors), pigments, additional fillers, compatibilizers for fillers (e.g., silane coupling agents or coating agents), fibers, etc. Those skilled in the art can easily select the combination of vulcanized rubber compounds for subsequent mixing and vulcanization and their respective amounts according to the specific rubber product to be desired. Depending on the intended use of the vulcanized material, these additives may be selected and used in conventional amounts.

[0037] Processing aids improve the processability of the composition and include oils, such as mineral oils, vegetable oils, synthetic oils, or any mixture thereof. Stearic acid may be used in an amount of about 5 to 75 phr, preferably about 10 to 50 phr. Common processing aids include oils, such as aromatic oils. Examples of such oils include processed distilled aromatic extracts (TDAE), residual aromatic extracts (RAE), mild extract solvates (MES), and bio-based oil seed derivatives. The oils for use in the tire composition of the present invention are not particularly limited and may be any known to those skilled in the art. For example, the oil may be one or more selected from the group consisting of processing oils, such as aromatic oils, naphthenic oils, and paraffin oils; vegetable oils, such as coconut oil; and synthetic oils, such as alkylbenzene oils and castor oils.

[0038] The vulcanizing agent of the composition is not particularly limited and may be any known in the art. For example, the vulcanizing agent may be sulfur. The amount of the vulcanizing agent is not particularly limited, and an amount effective for achieving satisfactory curing of the composition can be easily selected by a person skilled in the art. The vulcanizing agent (e.g., sulfur) may be used in an amount ranging from about 0.1 to about 10 phr, preferably from about 0.1 to about 5 phr, for example from about 0.5 to about 3 phr. For example, the tire composition may contain 0.1 to 3 phr, preferably from 0.5 to 2 phr, for example from 1 to 1.5 phr of vulcanizing agent.

[0039] The vulcanization accelerator for use in the composition is not particularly limited and may be any known in the art. The accelerator includes thiazoles, dithiocarbamates, thiuram, guanidine, and sulfonamides. Examples of suitable accelerators are thiazole-type vulcanization accelerators, such as 2-mercaptobenzothiazole (MBT), dibenzothiazyl disulfide (MBTS), N-cyclohexyl-2-benzothiazyl sulfenamide (CBS), and N-tert-butyl-2-benzothiazolyl sulfenamide (TBBS); guanidine-type vulcanization accelerators, such as 1,3-diphenylguanidine (DPG); thiuram-based vulcanization accelerators, such as tetramethyl thiuram disulfide, tetrabutyl thiuram disulfide, tetradodecyl thiuram disulfide, tetraoctyl thiuram disulfide, and tetrabenzyl thiuram disulfide; and dithiocarbamate compounds, such as zinc dimethyl dithiocarbamate; and other dialkyl dithiophosphate zincs are included. Preferably, the vulcanization accelerator may be a combination of dibenzothiazyl disulfide (MBTS), N-cyclohexyl-2-benzothiazyl sulfenamide (CBS), 1,3-diphenylguanidine (DPG), and / or tetrabenzylthiuram disulfide (TBZTD). The amount of vulcanization accelerator to be used in the composition is not particularly limited and may be, for example, in the range of about 0.5 to about 10 phr, preferably about 1 to about 8 phr, more preferably about 2 to about 6 phr. Preferably, the vulcanization accelerator may comprise an amount of 1 to 3 phr of N-cyclohexyl-2-benzothiazyl sulfenamide (CBS), an amount of 0.1 to 2 phr of 1,3-diphenylguanidine (DPG), and an amount of 0.1 to 2 phr of tetrabenzylthiuram disulfide (TBZTD).

[0040] The vulcanization accelerator for use in the composition is not particularly limited and may be any known to those skilled in the art. For example, the vulcanization accelerator may be zinc oxide (ZnO) and a fatty acid. The fatty acid may be any saturated or unsaturated, or linear or branched fatty acid. The number of carbon atoms in the fatty acid is also not particularly limited, but may be 1 to 30, or 15 to 30. For example, the fatty acid may be one or more selected from the group consisting of cyclohexanoic acid (cyclohexane carboxylic acid), naphthenic acid having a side chain, such as alkyl cyclopentane, saturated fatty acid, such as hexanoic acid, octanoic acid, decanoic acid (including branched carboxylic acid, such as neodecanoic acid), dodecanoic acid, tetradecanoic acid, hexadecanoic acid, and octadecanic acid (stearic acid), unsaturated fatty acid, such as methacrylic acid, oleic acid, linoleic acid and linolenic acid, and resinous acid, such as rosin, toll lactic acid and abietic acid. Preferably, the vulcanization accelerating agent of the present invention is preferably zinc oxide (ZnO) and stearic acid. The total amount of the vulcanization accelerating agent is not particularly limited, but may be 1 to 10 phr, preferably 1.5 to 7 phr, for example 2 to 5 phr. Preferably, zinc oxide can be used in an amount of about 1 to about 10 phr, preferably about 2 to about 5 phr, more preferably about 2 to about 3 phr. Stearic acid can be used in an amount of about 0.1 to about 5 phr, preferably about 0.5 to about 3 phr.

[0041] Additional reinforcing fillers, such as carbon black, carbon nanotubes, short carbons, polyamides, polyesters, natural fibers, calcium carbonate, clay, alumina, aluminosilicates, etc., or any mixture thereof, may also be present in the tire composition of the present invention. In one embodiment, it comprises aluminum hydroxide as an additional inorganic filler, preferably 5 to 20 phr of aluminum hydroxide.

[0042] If carbon black is present, it may be furnace black, channel black, or lamp black. For example, the carbon black may be one or more selected from the group consisting of super-wear furnace (SAF) black, high-wear furnace (HAF) black, high-speed extrusion furnace (FEF) black, fine furnace (FF) black, medium super-wear furnace (ISAF) black, semi-reinforced furnace (SRF) black, medium processability channel black, hard processability channel black, and conductive channel black. Other carbon blacks that may be used include acetylene black. In one embodiment, the carbon black may be recycled carbon black. The carbon black may be in a pelletized form or as unpelletized aggregated lumps. A specific example of carbon black for use in the tire composition of the present invention is recycled carbon black supplied by Bolder Industries under the trade name Bolder Black REC CB. The amount of carbon black that may be present is not particularly limited, but may be 0.1 to 10 phr, for example 0.5 to 8 phr, or 2 to 7 phr, for example 4 to 6 phr.

[0043] Advantageously, the only silica-based filler present in the vehicle tire composition of the present invention is the RHA silica described herein, i.e., no additional silica is present. Thus, RHA silica may constitute all silica fillers in the composition. In some embodiments, it may constitute all reinforcing fillers in the tire composition. However, the presence of additional silica-based fillers or additional non-silica-based fillers is not necessarily excluded. If any additional silica is present, it may be selected from any known in the art, including, but not limited to, precipitated amorphous silica, wet silica (hydrated silica), dry silica (anhydrous silica), fumed silica, calcium silicate, aluminum silicate, magnesium silicate (e.g., Mg2SiO4, MgSiO3), magnesium calcium silicate (CaMgSiO4), and aluminum calcium silicate (e.g., Al2O3,CaO2SiO2).

[0044] The tire composition may include additional fillers known to those skilled in the art. For example, the tire composition comprises aluminum hydroxide, talc, alumina (Al2O3), aluminum hydrate (Al2O3.H2O), aluminum hydroxide (Al(OH)3), aluminum carbonate (Al2(CO3)2), magnesium aluminum oxide (MgOAl2O3), pyrophyllite (Al2O3.4SiO2.H2O), bentonite (Al2O3.4SiO2.2H2O), mica, kaolin, glass balloon, glass bead, calcium oxide (CaO), calcium hydroxide (Ca(OH)2), calcium carbonate (CaCO3), magnesium carbonate, magnesium hydroxide (Mg(OH)2), magnesium oxide (MgO), magnesium carbonate (MgCO3), potassium titanate, barium sulfate, zirconium oxide (ZrO2), zirconium hydroxide (Zr(OH)2.nH2O), It may include one or more additional fillers selected from the group consisting of zirconium carbonate (Zr(CO3)2), crystalline aluminosilicate, and reinforcing grade zinc oxide (i.e., reinforcing zinc oxide). The amount of additional filler may be 5 to 200 phr, e.g. 10 to 150 phr, or 25 to 100 phr.

[0045] The anti-deterioration agent for use in the tire composition of the present invention is not particularly limited and may be any known to those skilled in the art. The anti-deterioration agent may be an antioxidant and / or an ozone inhibitor. For example, the anti-deterioration agent may be one or more selected from the group consisting of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD), 2,2,4-trimethyl-1,2-dihydroquinoline polymer (TMQ), and N'-(1,3-dimethylbutylene)-3-hydroxy-naphthohydrazide (BMH). Preferably, the anti-deterioration agent is a combination of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD), 2,2,4-trimethyl-1,2-dihydroquinoline polymer (TMQ), and N'-(1,3-dimethylbutylene)-3-hydroxy-naphthohydrazide (BMH). The amount of each degradation inhibitor may be 0.1 to 3 phr, preferably 0.2 to 2 phr. The total amount of degradation inhibitor may be 0.1 to 5 phr, preferably 1 to 3 phr.

[0046] A coating agent may be used to reduce the formation of silica aggregates during compounding. If present, it may be used in an amount of up to 20 phr, preferably about 1 to about 15 phr. In one embodiment, no additional coating agent is present. The coating agent is not particularly limited and may be any known in the art. Suitable silica-based coating agents include silanes, such as alkylalkoxysilanes, such as hexadecyltrimethoxysilane, octyltriethoxysilane, and hexyltrimethoxysilane. In one embodiment, the coating agent may be grafted onto the polymer first. Additionally, it may be used in a free state (i.e., not grafted first) or grafted onto the silica surface.

[0047] A coupling agent may be present that inhibits aggregation by binding to the silanol groups of silica and also functions to covalently bond the silica filler to the rubber component matrix. The appropriate amount of any coupling agent can be determined by a person skilled in the art by considering the molecular weight, the number of functional groups contained, and their reactivity. Most coupling agents can be used in equal molar amounts based on the amount of silica. The coupling agent for use in the vehicle tire composition of the present invention is not particularly limited and may be any known to a person skilled in the art. In one embodiment, the coupling agent may be first grafted onto the polymer. Additionally, it may be used in a free state (i.e., not first grafted) or grafted onto the surface of silica.

[0048] Generally, the coupling agent will be a silane coupling agent, for example, a difunctional silane. For example, silane coupling agents include bis(3-triethoxysilylpropyl) tetrasulfide, bis(3-triethoxysilylpropyl) trisulfide, bis(3-triethoxysilylpropyl) disulfide, bis(2-triethoxysilylethyl) tetrasulfide, bis(3-trimethoxysilylpropyl) tetrasulfide, bis(2-trimethoxysilylethyl) tetrasulfide, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, 3-triethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, It may be one or more selected from the group consisting of 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, 3-trimethoxysilylpropylbenzothiazoyl tetrasulfide, 3-triethoxysilylpropylbenzothiazoyl tetrasulfide, 3-triethoxysilylpropylmethacrylate monosulfide, 3-trimethoxysilylpropylmethacrylate monosulfide, bis(3-diethoxymethylsilylpropyl)tetrasulfide, 3-mercaptopropyldimethoxymethylsilane, dimethoxymethylsilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, and dimethoxymethylsilylpropylbenzothiazoyl tetrasulfide. Preferably, the silane coupling agent is bis(3-triethoxysilylpropyl)tetrasulfide. A specific example of a silane coupling agent for use in the present invention is Si 39® of Evonik Industries AG. The amount of silane coupling agent is not particularly limited, but may be 2 to 20 phr, preferably 5 to 18 phr, more preferably 5 to 15 phr.

[0049] The vehicle tire composition according to the present invention may be manufactured by a method known in the art, which may include the step of introducing an RHA silica filler and a lignin sulfonate into a rubber component to produce a vulcanizable rubber compound, that is, the step of mixing (also known as compounding) the rubber component with the RHA silica, the lignin sulfonate, and any other component described herein to produce a vulcanizable rubber compound. In the manufacture of the tire composition of the present invention, the method of combining each component is not particularly limited, and any method known in the art may be used. For example, all components may be blended and kneaded at once, or they may be blended and kneaded in multiple stages. For blending and kneading, a kneader, such as a roll kneader, an internal mixer, or a Banbury mixer may be used. When molding the tire composition into any desired shape, such as a sheet or a strip shape, any known molding machine, such as an extrusion molder or a compression molder, may be used.

[0050] Mixing of the components will typically be performed in stages where components can be added. A multi-stage mixing process is generally preferred to optimize the dispersion of RHA silica and lignin sulfonate and may involve using more than one mixer, for example, different mixers arranged in series. For example, when mixing a compound for tire treads, the mixing process may involve an initial mixing stage to produce a masterbatch, followed by one or more additional non-productive mixing stages, and finally a productive mixing stage in which a curing agent (i.e., sulfur or sulfur-donor and accelerator(s)) is added. Mixers that may be used are well known in the art and include, for example, open mills or Banbury-type mixers having tangential or interlocking rotors.

[0051] Generally, an initial masterbatch is produced by mixing rubber, RHA silica, and lignin sulfonate with any optional processing aid, zinc oxide, stearic acid, a degradation inhibitor (e.g., antioxidant, ozone inhibitor), pigment, additional filler, compatibilizer, and coupling agent (if present). Following this initial masterbatch, an additional masterbatch process may be performed to add additional fillers and additives, or a non-productive mixing step in which no additional components are added may be performed. Any non-productive mixing step may be used to further disperse components within the rubber (e.g., fillers) or to reduce the viscosity of the mixed rubber compound.

[0052] During mixing, the temperature is maintained below a predetermined level to prevent premature crosslinking of the composition. Generally, the temperature may be maintained below 150°C, preferably below 140°C. In the preparation of the initial masterbatch, mixing may be performed at a temperature of, for example, about 80 to about 110°C, e.g., about 100°C. In the non-productive mixing stage, the temperature may be raised, for example, to a maximum of about 150°C, e.g., about 130°C. If any additional compatibilizer is added during mixing, it may be essential to perform mixing at a higher temperature so that they react with the silica surface. The mixing time may be variable but can be easily determined by a person skilled in the art based on the composition of the mixture and the type of mixer used. Generally, a mixing time of at least 1 minute, preferably 2 to 30 minutes, should be sufficient to obtain the desired homogeneous composition.

[0053] The final mixing step involves adding a vulcanizing agent containing an accelerator(s) and a deterioration inhibitor. The temperature of this mixing step will generally be lower, for example, in the range of about 40 to about 60°C, e.g., about 50°C. Additionally, after this final mixing, an additional non-productive mixing step in which no additional components are added may follow.

[0054] The most suitable mixing type can be easily selected to achieve a vulcanizable rubber compound. The mixing speed can be easily determined, but it may be a speed range of, for example, about 20 to about 100 rpm, for example, about 30 to about 80 rpm, preferably about 50 rpm.

[0055] Vulcanizable rubber compounds may be provided as uncured (so-called "green") tire components for final vulcanization to cure the composition. Curing to crosslink the rubber components may be performed by known methods. Thus, a subsequent process step is to vulcanize the vulcanizable rubber compound by heating at a predetermined temperature for a predetermined time. For example, in the tire industry, after manufacturing the uncured rubber (so-called "green body"), curing is carried out in a press mold, simultaneously crosslinking the rubber components, and molding the components into a final tire. Vulcanization cures the rubber through crosslinking, primarily through sulfur crosslinking. Vulcanization methods and conditions for curing tire compositions are well known to those skilled in the art. Suitable vulcanization conditions generally involve heating at a predetermined temperature in the range of 120 to 200°C, e.g., 140 to 180°C, for a predetermined duration of 5 to 180 minutes, e.g., 5 to 120 minutes.

[0056] The vehicle tire compositions described herein are particularly used in the manufacture of vehicle tires, especially in the manufacture of tire components, such as tire treads. Tire treads can be used for any vehicle tire, but they are particularly used in the manufacture of automotive tire treads.

[0057] As described above, it is important that in the present invention, RHA silica is used together with lignin sulfonate. Accordingly, the present invention relates to the use of rice husk ash silica in a vehicle tire composition, wherein the vehicle tire composition comprises 100 phr of rubber components and 2 to 25 phr of lignin sulfonate.

[0058] The present invention is further described in the manner of the following non-limiting embodiments.

[0059] Examples

[0060] measurement method

[0061] Mooney's point

[0062] Mooney viscosity was measured according to the ASTM D1646 standard.

[0063] Elastic modulus (E')

[0064] The elastic modulus (E') is used to evaluate grip performance. Dynamic physical tests to determine E' at 30°C were conducted according to the ISO 4664 standard.

[0065] Potassium content

[0066] The metal content, including potassium, in RHA silica is measured by inductively coupled plasma-optical emission spectroscopy (ICP-OES) according to ISO 19050:2021(en). Briefly, silica elements are dissolved in hydrochloric acid. The solution is processed on a hot plate to dissolve the element of interest and then analyzed on an instrument.

[0067] Weak coefficient (WK)

[0068] The weak coefficient of RHA silica is measured by laser light scattering based on the principle of laser diffraction, as described in U.S. Patent No. 6,180,076, the contents of which are incorporated herein by reference. Measurements are performed using a CILAS Granulometer 1064 L. For measurement, 1.3 g of precipitated silica is transferred to 25 ml of water and sonicated at 100 W (90% pulse) for 4.5 minutes. Subsequently, the solution is transferred to a measurement cell and sonicated for an additional 1 minute. During sonication, detection is performed using two laser diodes positioned at different angles to the sample. The laser beam is diffracted according to the principle of light diffraction. The formed diffraction pattern is evaluated using a computer. The method allows for the determination of particle size distribution over a wide measurement range (approximately 40 nm to 500 μm).

[0069] The curve is generated to show the first maximum in the particle size distribution range of 1.0 to 100 μm and an additional maximum in the range of less than 1.0 μm. The peak in the range of 1.0 to 100 μm represents the proportion of unground silica particles after sonication. These significantly coarse particles are not well dispersed in the rubber mixture. The second peak, representing significantly smaller particle sizes (less than 1.0 μm), represents some of the silica particles that were not ground during sonication. These very small particles are well dispersed in the rubber mixture.

[0070] Therefore, the WK coefficient is the ratio of the peak height of non-degradable particles (B) with a maximum value in the range of 1.0 to 100 μm to the peak height of degradable particles (A) with a maximum value of less than 1.0 mm.

[0071] WK coefficient = B / A

[0072] In the above formula:

[0073] B = Peak height of non-degradable particles (maximum values ​​range from 1 to 100 μm);

[0074] A = Peak height of degradable particles (maximum value less than 1 μm).

[0075] Therefore, the WK coefficient is a measure of the "degradability" (=dispersibility) of silica. The smaller the WK coefficient, the more easily precipitated silica disperses, and the more particles decompose during introduction into the rubber.

[0076] The important point here is that energy injection by ultrasound mimics energy injection by mechanical force in the tire industry's kneaders. It was shown that the WK coefficient is a measure of the dispersibility of precipitated silica.

[0077] Cetyltrimethylammonium bromide (CTAB) adsorption method

[0078] The CTAB specific surface area is the external surface. The surface area of ​​RHA silica was measured by the CTAB method according to ISO 5794-1G.

[0079] Brunauer-Emmet-Teller (BET) specific surface area

[0080] The average specific surface area of ​​RHA silica is determined by N2 adsorption according to the BET method as described in the literature [Journal of the American Chemical Society, Vol. 60, page 309, February 1938], which corresponds to the standard NF ISO 5794-1, Appendix D (June 2010).

[0081] general method

[0082] The following ingredients were compounded in a Banbury mixer in the amounts mentioned in Table 2 below.

[0083] ingredient

[0084] Elastomer:

[0085] Functionalized Solution Styrene-Butadiene Rubber (ENEOS HPR520) (SSBR)

[0086] Natural rubber (NR)

[0087] Silica: Sand silica (STD-SiO2)(Ultrasil VN3, Evonik)

[0088] Rice husk silica (STD-SiO2) (K160, Wilmar)

[0089] Hydrocarbon resin:

[0090] Hydrocarbon resin 1 (Synthomer Impera E1780) (Res1 C5-H)

[0091] Hydrocarbon resin 2 (Synthomer Impera E1775)(Res2 C9-H)

[0092] Additional additives:

[0093] Recycled Carbon Black (Bolder Black REC CB, Bolder Industries)

[0094] Silane (Evonik Industries Si69)

[0095] Lignin sulfonate (Borresperse NA, Borregaard Lignotech)

[0096] Grinded rubber

[0097] Higilite

[0098] sulfur

[0099] 1,3-Diphenylguanidine (DPG)

[0100] Zinc oxide (ZnO)

[0101] Stearic acid (ST. Ac)

[0102] N-cyclohexyl-2-benzothiazyl sulfenamide (CBS)

[0103] 2,2,4-trimethyl-1,2-dihydroquinoline polymer (TMQ)

[0104] N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine(6PPD)

[0105] Microcrystalline wax blend (Wax)

[0106] Tetrabenzylthiuram disulfide (TBzTD)

[0107] Zn salts of fatty acids

[0108] N'-(1,3-dimethylbutylene)-3-hydroxy-naphthohydrazide (BMH)

[0109] Silica properties

[0110] [Table 1]

[0111]

[0112] Tire composition

[0113] The components of Table 2 provided in phr were compounded according to the general method described above:

[0114] [Table 2]

[0115]

[0116] A series of tests were performed on the compounds generated according to the measurement techniques described above. The results are described in Table 3.

[0117] [Table 3]

[0118]

[0119] From the results in Table 3, it can be confirmed that lignin sulfonates act as stiffness enhancers for rubber compounds. The effect of lignin sulfonates is enhanced when RHA silica is used instead of sand silica having a similar surface area. As described above, without being bound by theory, the inventors [identify] the higher content of potassium ions (K) present in RHA silica + It is believed that the electrostatic force can enhance the interaction between silica and lignin sulfonate. As a result, the efficacy of lignin as a stiffness enhancer is increased.

Claims

Claim 1 A vehicle tire composition comprising 100 phr of a rubber component; 50 to 160 phr of silica obtained from rice husk ash; and 2 to 25 phr of lignin sulfonate. Claim 2 A vehicle tire composition according to claim 1, comprising 50 to 120 phr of the silica, preferably 50 to 90 phr of the silica. Claim 3 A vehicle tire composition according to claim 1 or 2, comprising 5 to 20 phr of lignin sulfonate, preferably 5 to 15 phr of lignin sulfonate. Claim 4 A tire composition for a vehicle according to any one of claims 1 to 3, wherein the rubber component comprises butadiene rubber (BR); styrene-butadiene rubber (SBR); natural rubber (NR); or a combination thereof; preferably, the rubber component comprises solution-polymerized styrene-butadiene rubber (SSBR) and natural rubber (NR). Claim 5 A vehicle tire composition according to claim 4, comprising 40 to 80 phr of solution-polymerized styrene butadiene rubber, preferably 50 to 70 phr, or about 60 phr of solution-polymerized styrene butadiene rubber; and 20 to 60 phr of natural rubber, preferably 30 to 50 phr of natural rubber, or about 40 phr of natural rubber. Claim 6 In any one of claims 1 to 5, the silica has a CTAB surface area of ​​at least 100 m² 2 / g, preferably at least 120 m 2 / g, preferably at least 140 m 2 / g and / or, the above silica has a CTAB surface area of ​​up to 220 m² 2 / g, preferably up to 200 m 2 / g, preferably up to 170 m 2 Vehicle tire composition, with a particle size of 1 / g. Claim 7 A vehicle tire composition according to any one of claims 1 to 6, wherein the silica has a potassium content of 500 ppm or less based on the silica as measured by the inductively coupled plasma mass spectrometry described in the examples, preferably the silica has a potassium content of 400 ppm or less based on the silica, preferably less than 350 ppm, and / or the silica has a potassium content of 100 ppm or more based on the silica, preferably 200 ppm or 300 ppm or more. Claim 8 A vehicle tire composition according to any one of claims 1 to 7, wherein the silica has a weak coefficient of 20 or less as measured by laser light scattering as described in the example, preferably the silica has a weak coefficient of 15 or less, preferably 10 or less. Claim 9 A vehicle tire composition comprising aluminum hydroxide in any one of claims 1 to 8. Claim 10 A vehicle tire comprising a vehicle tire composition according to any one of claims 1 to 9. Claim 11 A method for manufacturing a vehicle tire composition according to any one of claims 1 to 9, wherein the method comprises the step of introducing a silica filler and a lignin sulfonate into a rubber matrix to produce a vulcanizable rubber compound; and the step of heating the vulcanizable rubber compound at a predetermined temperature and for a predetermined time to vulcanize it; wherein the composition comprises a silica filler obtained from 50 to 160 phr of rice husk ash and 2 to 25 phr of lignin sulfonate. Claim 12 Use of rice husk ash silica in a vehicle tire composition, wherein the vehicle tire composition comprises 100 phr of rubber components and 2 to 25 phr of lignin sulfonate. Claim 13 Use of rice husk ash silica in a vehicle tire composition containing lignin sulfonate to improve the stiffness enhancement of lignin sulfonate.

Images