Bio-based reinforcing resin, preparation method, rubber composition and application

Abstract

The invention belongs to the technical field of rubber, and discloses bio-based reinforced resin, a preparation method, a rubber composition and application. The bio-based reinforced resin is prepared from lignin, cashew nut shell oil, rosin or derivatives thereof and a vegetable fat modifier, the biochar content is up to 100%, the Mooney viscosity and MH of a sizing material are obviously reduced, and the bio-based reinforced resin has the advantages of long scorching time and high vulcanization speed in the sizing material application process.

Description

Technical Field

[0001] This application belongs to the technical field of rubber, and specifically relates to a bio-based reinforcing resin, a preparation method, a rubber composition and an application. Background Art

[0002] Rubber reinforcing resins, as key chemical additives to enhance the performance of rubber materials, have extensive applications in the fields of rubber products such as tires, shoe soles, and seals. According to the differences in chemical structure and application requirements, rubber reinforcing resins are subdivided into various types. Among them, phenolic resins have become indispensable organic reinforcing materials in the rubber industry due to their excellent reinforcing performance. Phenolic resins are formed by the condensation polymerization of phenol and formaldehyde under acidic conditions. According to their different molecular structures, they can be divided into two types: linear and branched. Linear phenolic resins exhibit unique advantages in rubber reinforcement due to their good solubility and plasticity. However, they usually require the addition of a curing agent (such as hexamethylenetetramine HMT) to form an interpenetrating network structure (IPN), thereby significantly improving the hardness, wear resistance, and heat resistance of rubber.

[0003] However, as a traditional petroleum-based reinforcing agent, the non-renewability of its raw materials, environmental pollution during the production process, and potential risks to human health have become key factors restricting its sustainable development. With the awakening of global environmental awareness and the popularization of the concept of sustainable development, the tire manufacturing industry is actively seeking renewable and bio-based materials as substitutes for traditional petroleum-based reinforcing agents. Many internationally well-known tire companies, such as Michelin and Pirelli, have clearly announced the timetables and specific goals for using sustainable materials, aiming to gradually reduce their dependence on traditional petroleum-based materials and increase the proportion of bio-based and renewable materials used.

[0004] In response to this trend, researchers have made various modification attempts on phenolic resins to improve their renewability and environmental friendliness. For example, modifying phenolic resins by adding oils such as tall oil or cashew nut oil not only improves the renewability of the resin but also improves its physical and chemical properties to a certain extent. In the existing technical literature, a number of patents on bio-based modified phenolic resins have been published, such as a cashew shell oil modified resorcinol aldehyde resin and its preparation method and application disclosed in CN105585679B, a cashew nut oil modified phenolic resin and its preparation method disclosed in CN102558473B, and a modified phenolic resin adhesive and its preparation method and tire rubber disclosed in CN104449500A. In addition, there are also patents on lignin-based reinforcing resins (such as a lignin-based reinforcing resin and its preparation method disclosed in CN103509164A) and modified cashew nut oil (such as modified cashew nut oil, rubber plasticizer and their preparation methods and applications disclosed in CN 114605259 A). These materials have improved the renewability of rubber products to a certain extent.

[0005] Although these modified materials have met the production needs of rubber products to a certain extent and have made initial progress in sustainability, the materials used still contain a large amount of petrochemical materials, and only part of them contain bio-based materials, which are not completely bio-based, and the degree of bio-based materials still needs to be improved. Therefore, the development of a bio-based reinforcing resin that is completely based on renewable resources, has high reinforcing properties and is environmentally friendly is still an important issue that needs to be solved urgently in the current rubber industry. Summary of the invention

[0006] In view of the deficiencies of the prior art, the present application aims to provide a bio-based reinforcing resin, wherein the biochar content in the bio-based reinforcing resin reaches 100%, and compared with conventional solid phenolic reinforcing resins, the bio-based reinforcing resin significantly reduces the Mooney viscosity and MH of the rubber compound, and exhibits the advantages of long scorch time and fast vulcanization speed during the application of the rubber compound. In other aspects of the present application, a preparation method of the bio-based reinforcing resin, a rubber composition containing the bio-based reinforcing resin, and the application of the bio-based reinforcing resin in rubber products are also provided.

[0007] In one aspect of the present application, a bio-based reinforcing resin is provided, wherein the raw materials for preparing the bio-based reinforcing resin include lignin, cashew nut shell liquid, rosin or its derivatives and a vegetable oil modifier.

[0008] In one embodiment, the raw materials for preparing the bio-based reinforcing resin include, by weight: 2 to 100 parts of lignin, 500 to 600 parts of cashew nut shell oil, 0 to 10 parts of rosin or its derivatives, and 0 to 7 parts of a vegetable oil modifier.

[0009] In one embodiment, the raw materials for preparing the bio-based reinforcing resin include, by weight: 100 parts of lignin, 500-600 parts of cashew nut shell oil, 10 parts of rosin or its derivatives, and 7 parts of a vegetable oil modifier.

[0010] In one embodiment, the bio-based reinforcing resin has a viscosity of 17,000 to 47,000 mPa·S.

[0011] In one embodiment, the thermal cracking products of lignin include acetic acid, 4-vinyl-2-methoxyphenol, 2,3-dihydrobenzofuran, 2-methoxy-4-methylphenol and guaiacol.

[0012] In one embodiment, the mass percentages of acetic acid, 4-vinyl-2-methoxyphenol, 2,3-dihydrobenzofuran, 2-methoxy-4-methylphenol and guaiacol in the thermal cracking product of lignin are 0-13%, 5-15%, 1-9%, 1-7% and 1-2%, respectively.

[0013] In one embodiment, the mass percentage contents of acetic acid, 4-vinyl-2-methoxyphenol, 2,3-dihydrobenzofuran, 2-methoxy-4-methylphenol, and guaiacol in the pyrolysis product of lignin are 10-13%, 10-13%, 3-6%, 3-4%, and 1-2% respectively.

[0014] In one embodiment, the pyrolysis conditions are: temperature 400 °C, time 0.2 min.

[0015] In one embodiment, the lignin is obtained by extraction from plant straws.

[0016] In one embodiment, the lignin is extracted from plant straws by the biological solvent method.

[0017] In one embodiment, the extraction method of the lignin includes:

[0018] Acid-hydrolyzing the crushed plant straws with an organic acid, and separating to obtain a reaction solution;

[0019] Reducing the pressure of the reaction solution to concentrate and remove the organic acid to obtain a concentrated solution;

[0020] Mixing the concentrated solution with water and heating for reaction to obtain the lignin.

[0021] In one embodiment, the plant straws are selected from one or more of straws of gramineous crops, leguminous crops, tuber crops, oil crops, fiber crops, and agricultural product processing by-products.

[0022] In one embodiment, the straws of gramineous crops are selected from one or more of wheat, rice straw, corn, sorghum, oats, rye, and reed.

[0023] In one embodiment, the straws of leguminous crops are selected from one or more of soybean, broad bean, pea, cowpea, and peanut vine.

[0024] In one embodiment, the straws of tuber crops are selected from one or two of sweet potato vine and potato vine.

[0025] In one embodiment, the straws of oil crops are selected from one or more of rape, peanut, and sesame.

[0026] In one embodiment, the straws of fiber crops are selected from one or two of bagasse and banana stalk.

[0027] In one embodiment, the agricultural product processing by-products are selected from one or more of rice husk, corn cob, peanut shell, and bagasse.

[0028] In one embodiment, the rosin or its derivative is selected from one or more of rosin, tall oil rosin, maleic rosin, rosin glycerol ester, polymerized rosin, and hydrogenated rosin.

[0029] In one embodiment, the vegetable oil modifier is selected from one or more of tall oil, tung oil, linseed oil, soybean oil, and vegetable oil acid.

[0030] In another aspect of the present application, a method for preparing the bio-based reinforcing resin is provided, comprising the following steps: polymerizing the lignin, cashew nut shell liquid, rosin or its derivatives and a vegetable oil modifier under the action of an acidic catalyst to obtain the bio-based reinforcing resin.

[0031] In one embodiment, the bio-based reinforcing resin has a viscosity of 17,000 to 47,000 mPa·S.

[0032] In one embodiment, the raw materials for preparing the bio-based reinforcing resin include, by weight: 2 to 100 parts of lignin, 500 to 600 parts of cashew nut shell oil, 0 to 10 parts of rosin or its derivatives, and 0 to 7 parts of a vegetable oil modifier.

[0033] In one embodiment, the raw materials for preparing the bio-based reinforcing resin include, by weight: 100 parts of lignin, 500-600 parts of cashew nut shell oil, 10 parts of rosin or its derivatives, and 7 parts of a vegetable oil modifier.

[0034] In one embodiment, the thermal cracking products of lignin include acetic acid, 4-vinyl-2-methoxyphenol, 2,3-dihydrobenzofuran, 2-methoxy-4-methylphenol and guaiacol.

[0035] In one embodiment, the rosin or its derivative is selected from one or more of rosin, tall oil rosin, maleic rosin, rosin glycerol ester, polymerized rosin, and hydrogenated rosin.

[0036] In one embodiment, the vegetable oil modifier is selected from one or more of tall oil, tung oil, linseed oil, soybean oil, and vegetable oil acid.

[0037] In one embodiment, the acidic catalyst is selected from one or more of oxalic acid, sulfuric acid, hydrochloric acid, phosphoric acid, p-toluenesulfonic acid, aminosulfonic acid, and dodecylbenzenesulfonic acid.

[0038] In one embodiment, the preparation method comprises the following steps:

[0039] The lignin and cashew nut shell liquid are uniformly mixed, and an acidic catalyst is added to carry out a catalytic polycondensation reaction;

[0040] Add the rosin or its derivatives and the vegetable oil modifier to further react to obtain the bio-based reinforcing resin.

[0041] In one embodiment, the lignin and the cashew shell oil are stirred and mixed at 55-65 °C.

[0042] In one embodiment, the reaction temperature of the catalytic polycondensation is 90-100 °C.

[0043] In one embodiment, the reaction product of the catalytic polycondensation is distilled and vacuum-treated to purify the reaction product.

[0044] In one embodiment, the distillation temperature is 150-160 °C.

[0045] In one embodiment, the pressure of the vacuum treatment is -0.098 to -0.1 MPa.

[0046] In one embodiment, the temperature of the further reaction is 165-185 °C.

[0047] In another aspect of the present application, a rubber composition is provided, and the rubber composition includes the bio-based reinforcing resin.

[0048] In one embodiment, the viscosity of the bio-based reinforcing resin is 17000-47000 mPa·S.

[0049] In one embodiment, the raw materials for preparing the bio-based reinforcing resin include, by weight: 2-100 parts of lignin, 500-600 parts of cashew shell oil, 0-10 parts of rosin or its derivatives, and 0-7 parts of vegetable oil modifier.

[0050] In one embodiment, the thermal pyrolysis products of the lignin include acetic acid, 4-vinyl-2-methoxyphenol, 2,3-dihydrobenzofuran, 2-methoxy-4-methylphenol, and guaiacol.

[0051] In one embodiment, the rosin or its derivatives are selected from one or more of rosin, tall oil rosin, maleic rosin, rosin glyceride, polymerized rosin, and hydrogenated rosin.

[0052] In one embodiment, the vegetable oil modifier is selected from one or more of tall oil, tung oil, linseed oil, soybean oil, and vegetable fatty acid.

[0053] In another aspect of the present application, the application of the bio-based reinforcing resin in rubber products is provided.

[0054] In one embodiment, the viscosity of the bio-based reinforcing resin is 17000-47000 mPa·S.

[0055] In one embodiment, the raw materials for preparing the bio-based reinforcing resin include, by weight: 2 to 100 parts of lignin, 500 to 600 parts of cashew shell oil, 0 to 10 parts of rosin or its derivatives, and 0 to 7 parts of vegetable oil modifier.

[0056] In one embodiment, the pyrolysis products of the lignin include acetic acid, 4-vinyl-2-methoxyphenol, 2,3-dihydrobenzofuran, 2-methoxy-4-methylphenol, and guaiacol.

[0057] In one embodiment, the rosin or its derivatives are selected from one or more of rosin, tall oil rosin, maleic rosin, rosin glyceride, polymerized rosin, and hydrogenated rosin.

[0058] In one embodiment, the vegetable oil modifier is selected from one or more of tall oil, tung oil, linseed oil, soybean oil, and vegetable fatty acid.

[0059] The beneficial effects of this application are as follows:

[0060] This application uses plant-derived materials as the basis and successfully prepares a brand-new bio-based reinforcing resin. Through detection and analysis, the biochar content of this resin is as high as 100%, which not only demonstrates its unique advantages in material sources but also indicates its great application potential in the field of developing environmentally friendly materials. At the same time, in terms of raw material selection, the plant-derived materials selected in this application are significantly easy to obtain and renewable, which is of great significance for alleviating the current resource shortage and promoting sustainable development.

[0061] The resin obtained in this application is in a liquid state, which is in sharp contrast to the traditional solid phenolic reinforcing resin. The application of the liquid resin in the rubber compound can significantly reduce the Mooney viscosity and at the same time reduce the MH (maximum torque) value, thereby effectively improving the processing performance of the rubber compound and providing more flexibility and convenience for the production and manufacturing of rubber products.

[0062] In addition, the resin obtained in this application exhibits the characteristics of a long scorch time and a fast vulcanization speed during the processing of the rubber compound. The extension of the scorch time means that the rubber compound has higher stability during processing and can effectively avoid processing defects caused by premature vulcanization. The acceleration of the vulcanization speed means a significant improvement in production efficiency, which can shorten the production cycle and reduce production costs while ensuring product quality. Specific embodiments

[0063] The technical solution of the present application will be clearly and completely described below in conjunction with specific embodiments. However, those skilled in the art will understand that the following described embodiments are part of the embodiments of the present application, rather than all embodiments, and are only used to illustrate the present application and should not be construed as limiting the scope of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the scope of protection of the present application. For those conditions not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. For reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0064] In the formulation design of tires and rubber products, reinforcing resins play a crucial role. According to the differences in raw materials, reinforcing resins are mainly divided into two categories: unmodified phenolic resins and modified phenolic resins. In the field of modified phenolic resins, the application of bio-based materials is becoming increasingly widespread, and these materials include, but are not limited to, lignin, tall oil, cashew nut shell oil, rosin, tung oil, linseed oil, soybean oil, and various vegetable oil fatty acids. However, although these modified resins incorporate bio-based components, their main raw materials still highly rely on traditional petrochemical industrial chain materials such as phenol and formaldehyde. Specifically, the bio-based component content in unmodified phenolic resins is 0% (calculated based on the biochar content detected by C14), while the bio-based content in bio-based modified phenolic resins ranges from 20% to 50%, leaving significant room for improvement.

[0065] Moreover, when traditional phenolic resins are used as rubber reinforcing agents, their performance has certain limitations. Since the softening point of phenolic resins is generally relatively high, usually in the range of 90 - 120 °C, this makes its effect on improving the processing performance of rubber compounds limited. At the same time, the high softening point also leads to a relatively high Mooney viscosity and maximum torque (MH) of the rubber compound, which is not conducive to the processing and molding of the rubber compound. Although cashew nut shell oil modified phenolic resin has improved the performance of phenolic resin to a certain extent, its scorch time (t5, t10, t35) is relatively short, which greatly limits its application in the manufacture of high-end tires such as all-steel radial tires.

[0066] In view of this, the present application has developed a bio-based reinforcing resin. The bio-based reinforcing resin uses special lignin, and cashew nut shell oil, rosin or its derivatives and vegetable oil modifiers under acidic conditions to obtain a bio-based reinforcing resin with 100% bio-carbon content through polymerization.

[0067] In one embodiment, a bio-based reinforcing resin is provided. The bio-based reinforcing resin is prepared from the following raw materials: lignin, cashew nut shell oil, rosin or its derivatives and vegetable oil modifiers.

[0068] The bio-based reinforcing resin is obtained by polymerizing the lignin, cashew shell oil, rosin or its derivatives, and plant oil modifier under the action of an acidic catalyst. This resin has the characteristics of being renewable, environmentally friendly, and having high performance, and can replace traditional petroleum-based reinforcing materials and be applied in fields such as rubber, plastics, and coatings.

[0069] In this application, the lignin is obtained by extracting from plant straws. Plant straws are by-products of agricultural production and are rich in cellulose, hemicellulose, and lignin. Among them, lignin accounts for 15% - 30% of the dry weight of the straw and is an important source of renewable aromatic compounds. Extracting lignin from straw can realize the resource utilization of agricultural waste, reduce environmental pollution, and at the same time reduce the production cost of bio-based materials. Chemical extraction methods, biological extraction methods, and physical extraction methods can be used. Chemical extraction methods such as alkali boiling method, acid precipitation method, and solvent extraction method. Biological extraction uses microorganisms (such as white rot fungi) or enzyme preparations (such as lignin peroxidase, laccase, etc.) to biologically treat the straw, and through biodegradation, lignin is separated from hemicellulose and cellulose. Physical extraction methods such as mechanical crushing method and ultrasonic method; the mechanical crushing method destroys the cell wall of the straw by means of mechanical rolling, grinding, etc. to release lignin; the ultrasonic method uses the cavitation effect and mechanical effect of ultrasonic waves to destroy the cell wall structure and promote the dissolution and release of lignin.

[0070] In some embodiments, the lignin is extracted from plant straws by a bio-solvent method. Specifically, for example, the straw is crushed to an appropriate particle size to increase the contact area between the solvent and the straw, and optionally, alkali treatment or acid treatment of the straw is carried out to break some chemical bonds in the straw and promote the dissolution of lignin. The pretreated straw is mixed with the bio-solvent in a certain proportion, placed in an extraction device, and stirred or ultrasonically treated at a certain temperature (such as from room temperature to the boiling point of the solvent) to accelerate the dissolution of lignin. After the extraction is completed, the solid-liquid mixture is separated by methods such as filtration and centrifugation to obtain a solvent solution containing lignin. The bio-solvent is recovered by methods such as distillation and evaporation to realize the recycling of the solvent. The recovered lignin solution is further purified, such as through steps of precipitation, washing, and drying to obtain a high-purity lignin product. Among them, the bio-solvent is selected to have good solubility for lignin, such as ethanol, acetone, methanol, ethyl acetate, formic acid, acetic acid, etc., or their mixtures.

[0071] In some embodiments, the method for extracting lignin is as follows: The crushed plant straw is acid-hydrolyzed with an organic acid, and the reaction solution is separated. The organic acid can react with the lignin-carbohydrate complex in the straw, break its chemical bond, and gradually dissolve the lignin in the acid solution. The reaction solution is concentrated under reduced pressure to remove the organic acid to obtain a concentrated solution. Under reduced pressure conditions, the boiling point of the reaction solution can be reduced, and the organic acid in the reaction solution is removed by heating to obtain a concentrated lignin solution. The concentrated solution is mixed with water and heated for reaction. By diluting with water and stirring, impurities in the lignin are further removed. At the same time, the water washing process helps to remove possible esterification products, and finally the lignin is obtained.

[0072] In some embodiments, the particle size of the plant straw is 1-3 cm. The particle size refers to the size or dimension of particles and is an important parameter describing the microscopic characteristics of particulate materials. When the measured particle is closest to a homogeneous sphere (or combination) of a certain diameter, the diameter (or combination) of the sphere is regarded as the equivalent particle size of the measured particle. The particle size can be expressed in various ways such as single particle size, average particle size, equivalent particle size, etc. Among them, the average particle size can be arithmetic mean diameter, geometric mean diameter, volume average diameter, etc. For non-spherical particles, the equivalent particle size is usually used to describe their size, such as equivalent volume sphere equivalent diameter, equivalent surface area sphere equivalent diameter, etc. The measurement method of the particle size is not limited, including but not limited to microscopy (optical microscopy, electron microscopy, etc.), sieving method, sedimentation method, laser diffraction method, dynamic light scattering method (photon correlation spectroscopy), etc.

[0073] In some embodiments, the organic acid is selected from one or more of formic acid, acetic acid, and propionic acid. Preferably, the organic acid is selected from the combination of formic acid and acetic acid. More preferably, the mass percentage content of formic acid is 30-50%, and the mass percentage content of acetic acid is 25-45%. Specifically, the mass percentage content of formic acid can be 30%, 32%, 34%, 36%, 38%, 40%, 42%, 44%, 46%, 48%, 50%, and the mass percentage content of acetic acid can be 25%, 27%, 29%, 31%, 33%, 35%, 37%, 39%, 41%, 43%, 45%.

[0074] In some embodiments, the plant straw is selected from one or more of straws of gramineous crops, leguminous crops, tuber crops, oil crops, fiber crops, and agricultural product processing by-products.

[0075] Preferably, the gramineous crop straws are selected from one or more of wheat, rice straw, corn, sorghum, oats, rye, and reed. The leguminous crop straws are selected from one or more of soybean, broad bean, pea, cowpea, and peanut vine. The tuber crop straws are selected from one or two of sweet potato vine and potato vine. The oil crop straws are selected from one or more of rape, peanut, and sesame. The fiber crop straws are selected from one or two of bagasse and banana stalk. The agricultural product processing by-products are selected from one or more of rice husk, corncob, peanut shell, and bagasse.

[0076] More preferably, the plant straws are selected from one or more of wheat, rice straw, reed, corn, and soybean.

[0077] In the present application, pyrolysis refers to the process of breaking the chemical bonds in lignin molecules under anaerobic or low-oxygen conditions through high temperature (usually 300-900 °C) to generate small molecule gases, liquids (bio-oil), and solids (coke). Specifically, the acetyl group (O-acetyl) in lignin breaks at high temperature to release acetic acid. The side-chain methyl group (-OCH3) and vinyl group (-CH=CH2) of the guaiacyl unit (G-unit) form 4-vinyl-2-methoxyphenol through free radical recombination. The benzene ring structure of lignin opens at high temperature to form a five-membered ring ether (benzofuran) structure. The side-chain methyl group (-CH3) of the guaiacyl unit dehydrogenates at high temperature to form a methylation product (2-methoxy-4-methylphenol).

[0078] In some embodiments, the pyrolysis conditions are: temperature 400 °C, time 0.2 min.

[0079] Furthermore, the pyrolysis products of lignin include acetic acid, 4-vinyl-2-methoxyphenol, 2,3-dihydrobenzofuran, 2-methoxy-4-methylphenol, and guaiacol.

[0080] In some embodiments, the mass percentage contents of acetic acid, 4-vinyl-2-methoxyphenol, 2,3-dihydrobenzofuran, 2-methoxy-4-methylphenol, and guaiacol in the pyrolysis product of lignin are 0-13%, 5-15%, 1-9%, 1-7%, and 1-2%, respectively. Preferably, the mass percentage contents of acetic acid, 4-vinyl-2-methoxyphenol, 2,3-dihydrobenzofuran, 2-methoxy-4-methylphenol, and guaiacol in the pyrolysis product of lignin are 10-13%, 10-13%, 3-6%, 3-4%, and 1-2%, respectively. Specifically, the mass percentage content of acetic acid can be 0%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%; the mass percentage content of 4-vinyl-2-methoxyphenol can be 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%; the mass percentage content of 2,3-dihydrobenzofuran can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%; the mass percentage content of 2-methoxy-4-methylphenol can be 1%, 2%, 3%, 4%, 5%, 6%, 7%; and the mass percentage content of guaiacol can be 1%, 2%.

[0081] In this application, cashew nut shell liquid is a natural vegetable oil extracted from cashew nut shells, mainly composed of the following components: cardanol, accounting for about 40%-55%, which is the core component of cashew nut shell liquid and has the characteristics of phenolic compounds; cardanol dimers, accounting for about 15%-25%, which are dimers of cardanol; anacardic acid, accounting for about 10%-20%, which has antibacterial and anti-inflammatory properties; other components: including a small amount of aliphatic compounds, resin acids, and impurities. Cashew nut shell liquid is mainly extracted by the following methods: hot pressing method, extruding the oil from cashew nut shells through high temperature and high pressure; solvent extraction method, using organic solvents (such as hexane) to extract the oil and then recovering the solvent by distillation; supercritical fluid extraction, using supercritical carbon dioxide for extraction to retain more active ingredients.

[0082] In this application, in the bio-based reinforcing resin, rosin or its derivatives play an important role in enhancing the resin properties, improving the processing characteristics, and enhancing the comprehensive properties of the material. Rosin and its derivatives can form a cross-linked structure with components such as lignin and cashew nut shell liquid to improve the strength and toughness of the resin. Rosin is a natural resin, mainly derived from the secretions of plants such as pine trees. Rosin can be chemically modified to generate various derivatives, commonly including: hydrogenated rosin, disproportionated rosin, polymerized rosin, rosin esters, maleic anhydride-modified rosin.

[0083] In some embodiments, the rosin or its derivatives obtained by chemical modification may be selected from the following types: rosin, tall oil rosin, maleic rosin, glycerol ester of rosin, polymerized rosin, and hydrogenated rosin. One of them can be used alone, or two or more of them can be used in combination. Specifically, due to its excellent solubility, tall oil rosin can be uniformly mixed with other raw materials (such as lignin, cashew nut shell liquid), providing a good basis for subsequent processing. By introducing carboxylic acid groups, maleic rosin enhances its polarity, thereby improving the interfacial bonding force between the resin and the filler, and significantly enhancing the water resistance and weather resistance of the resin. After the esterification reaction between rosin and glycerol, glycerol ester of rosin is formed, which has good flexibility and compatibility, can effectively improve the flexibility of the resin, and enhance its compatibility with plant oil modifiers. After the polymerization reaction between rosin molecules, polymerized rosin is formed, with increased molecular weight, elevated softening point, and enhanced heat resistance, thus improving the mechanical strength and heat resistance of the resin. After the hydrogenation reaction of rosin, hydrogenated rosin is obtained, which has high stability and strong antioxidant properties, can delay the aging process of the resin, and thus extend its service life.

[0084] When two or more rosins or their derivatives are selected, they can work synergistically. For example, when combining glycerol ester of rosin with flexible properties and polymerized rosin with high strength, the resin can have both good flexibility and high mechanical strength, making it very suitable for application scenarios with high impact loads. When combining hydrogenated rosin with heat resistance and maleic rosin with weather resistance, the resin can remain stable in high-temperature environments and simultaneously possess excellent ultraviolet resistance and water resistance. When combining tall oil rosin with good processability and polymerized rosin with excellent mechanical properties, the resin has good fluidity during processing and excellent mechanical properties after molding, making it very suitable for the production of complex structural parts.

[0085] In this application, the plant oil modifier is a type of functional additive prepared from natural plant oils through physical or chemical modification means, aiming to improve the flexibility, compatibility, processability, and biodegradability of the resin. The core raw material of the plant oil modifier is natural plant oil, and the main sources include: common oil types: soybean oil, rapeseed oil, palm oil, castor oil, etc.; special oil types: tung oil (containing conjugated double bonds for crosslinking and curing), linseed oil (containing linolenic acid for oxidation polymerization). The long-chain fatty acid structure of plant oils can lower the glass transition temperature (Tg) of the resin. For example, epoxy soybean oil can lower Tg by 5 - 15 °C, significantly improving the low-temperature toughness of the resin. The ester bonds in plant oils are easily hydrolyzed under the action of microorganisms, which can accelerate the biodegradation of the resin. For example, the biodegradation rate of a resin containing 50% plant oil can reach more than 60% within 90 days.

[0086] In some embodiments, the vegetable oil modifier is selected from one or more of tall oil, tung oil, linseed oil, soybean oil, and vegetable oil fatty acid.

[0087] In some embodiments, the raw materials for preparing the bio-based reinforcing resin include, by weight: 2-100 parts of lignin, 500-600 parts of cashew shell oil, 0-10 parts of rosin or its derivatives, and 0-7 parts of vegetable oil modifier. Preferably, the raw materials for preparing the bio-based reinforcing resin include, by weight: 100 parts of lignin, 500-600 parts of cashew shell oil, 10 parts of rosin or its derivatives, and 7 parts of vegetable oil modifier. Specifically, by weight, the lignin can be 2 parts, 12 parts, 22 parts, 32 parts, 42 parts, 52 parts, 62 parts, 72 parts, 82 parts, 92 parts, 100 parts, the cashew shell oil can be 500 parts, 510 parts, 520 parts, 530 parts, 540 parts, 550 parts, 560 parts, 570 parts, 580 parts, 590 parts, 600 parts, the rosin or its derivatives can be 0 parts, 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, and the vegetable oil modifier can be 0 parts, 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts.

[0088] In some embodiments, the viscosity of the bio-based reinforcing resin is 17000-47000 mPa·s. The applicable standards for viscosity testing include, but are not limited to, ASTM D2196, ISO 3219, or GB / T 2794. Preferably, GB / T 2794 is used in this embodiment. GB / T 2794 calculates the viscosity based on the shear stress-shear rate relationship of Newtonian or non-Newtonian fluids, through the torque generated by a rotating rotor in the resin, combined with rotor parameters (such as size and rotation speed). Specifically, the viscosity of the bio-based reinforcing resin can be 17000 mPa·S, 19000 mPa·S, 21000 mPa·S, 23000 mPa·S, 25000 mPa·S, 27000 mPa·S, 29000 mPa·S, 31000 mPa·S, 33000 mPa·S, 35000 mPa·S, 37000 mPa·S, 39000 mPa·S, 41000 mPa·S, 43000 mPa·S, 45000 mPa·S, 47000 mPa·S.

[0089] In another embodiment of the present application, a method for preparing a bio-based reinforcing resin is provided, including the following steps: polymerizing the lignin, cashew shell oil, rosin or its derivatives, and vegetable oil modifier under the action of an acidic catalyst to obtain the bio-based reinforcing resin.

[0090] Specifically, the lignin and cashew shell oil are mixed evenly, and an acidic catalyst is added for catalytic polycondensation reaction; the rosin or its derivatives and plant oil modifiers are added for further reaction to obtain the bio-based reinforcing resin.

[0091] In some embodiments, the lignin and cashew shell oil are stirred and mixed at 55-65 °C. The condition of 55-65 °C means that the lignin and cashew shell oil are heated to and stably maintained within the temperature range of 55 degrees Celsius to 65 degrees Celsius (including 55 °C and 65 °C). Lignin is in a solid state or high-viscosity state at room temperature. Heating to 55-65 °C can significantly reduce its viscosity, promote molecular diffusion, and improve the mixing uniformity. Cashew shell oil is liquid at room temperature but has a high viscosity. Heating to 55-65 °C can further reduce its viscosity and enhance its compatibility with lignin. Specifically, the temperature can be 55 °C, 56 °C, 57 °C, 58 °C, 59 °C, 60 °C, 61 °C, 62 °C, 63 °C, 64 °C, 65 °C.

[0092] In some embodiments, the acidic catalyst is selected from one or more of oxalic acid, sulfuric acid, hydrochloric acid, phosphoric acid, p-toluenesulfonic acid, sulfamic acid, dodecylbenzenesulfonic acid. The acidic catalyst can provide protons (H + ), reduce the activation energy of the reaction, and promote the reaction between the active groups (such as phenolic hydroxyl groups, carboxyl groups, unsaturated double bonds, etc.) in the lignin and cashew shell oil molecules to form high-molecular compounds.

[0093] In some embodiments, the reaction temperature of the catalytic polycondensation is 90-100 °C. The molecular structure of lignin is complex and contains various active groups, such as phenolic hydroxyl groups and methoxy groups. Within the temperature range of 90-100 °C, the lignin molecules obtain sufficient thermal energy, and the molecular thermal motion intensifies, making the originally bound active groups more easily exposed and participate in the reaction. At the same time, this temperature can cause a certain degree of depolymerization and rearrangement of the lignin molecular chains, generating more reactive sites, which is beneficial to the polycondensation reaction with other raw materials such as cashew shell oil. The main components of cashew shell oil are unsaturated phenolic compounds such as cardanol. At 90-100 °C, the double bonds and other active sites in the cardanol molecules are more active, and can more effectively react with the lignin molecules and the subsequent added modifiers, promoting the progress of the polycondensation reaction. Common heating methods include oil bath heating, water bath heating, and electric heating, etc. Specifically, the reaction temperature of the catalytic polycondensation can be 90 °C, 91 °C, 92 °C, 93 °C, 94 °C, 95 °C, 96 °C, 97 °C, 98 °C, 99 °C, 100 °C.

[0094] In some embodiments, the reaction product of the catalytic polycondensation is distilled and vacuum-treated to purify the reaction product. Distillation utilizes the boiling point differences of the components. By heating, the low-boiling substances are vaporized and then condensed and recovered to achieve separation from the high-boiling resin. Vacuum treatment can significantly reduce the boiling point of the liquid, causing the high-boiling impurities to vaporize at a lower temperature and avoiding thermal decomposition of the resin.

[0095] In some embodiments, the distillation temperature is 150 - 160 °C. Specifically, the distillation temperature can be 150 °C, 151 °C, 152 °C, 153 °C, 154 °C, 155 °C, 156 °C, 157 °C, 158 °C, 159 °C, 160 °C.

[0096] In some embodiments, the pressure range in the vacuum treatment process is set to -0.098 MPa to -0.1 MPa. It should be noted that the degree of vacuum is usually characterized by gauge pressure (i.e., the pressure difference relative to the standard atmospheric pressure).

[0097] In some embodiments, the temperature of the further reaction is 165 - 185 °C. Lignin and cashew shell oil generate primary resin through acid-catalyzed polycondensation reaction. To optimize the performance, rosin or its derivatives and vegetable oil modifiers are introduced for further reaction. By controlling the temperature at 165 - 185 °C, the following are achieved: promoting the esterification reaction of phenolic hydroxyl groups and rosin anhydride to form a three-dimensional network structure; reducing free phenolic hydroxyl groups and decreasing the resin thermal decomposition rate; the vegetable oil modifier introduces long-chain fatty acids to enhance the flexibility and aging resistance of the resin. Specifically, the temperature of the further reaction can be 165 °C, 170 °C, 175 °C, 180 °C, 185 °C.

[0098] In another aspect of the present application, a rubber composition is provided. The rubber composition includes a bio-based reinforcing resin; the bio-based reinforcing resin is obtained by polymerizing the lignin, cashew shell oil, rosin or its derivatives, and vegetable oil modifier under the action of an acid catalyst.

[0099] In some embodiments, the raw materials for preparing the bio-based reinforcing resin include, by weight: 2 to 100 parts of lignin, 500 to 600 parts of cashew shell oil, 0 to 10 parts of rosin or its derivatives, and 0 to 7 parts of vegetable oil modifier. Preferably, the raw materials for preparing the bio-based reinforcing resin include, by weight: 100 parts of lignin, 500 to 600 parts of cashew shell oil, 10 parts of rosin or its derivatives, and 7 parts of vegetable oil modifier. Specifically, by weight, the lignin can be 2 parts, 12 parts, 22 parts, 32 parts, 42 parts, 52 parts, 62 parts, 72 parts, 82 parts, 92 parts, 100 parts; the cashew shell oil can be 500 parts, 510 parts, 520 parts, 530 parts, 540 parts, 550 parts, 560 parts, 570 parts, 580 parts, 590 parts, 600 parts; the rosin or its derivatives can be 0 parts, 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts; and the vegetable oil modifier can be 0 parts, 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts.

[0100] In some embodiments, the viscosity of the bio-based reinforcing resin is 17000 to 47000 mPa·s. The applicable standards for viscosity testing include, but are not limited to, ASTM D2196, ISO 3219, or GB / T 2794. Preferably, GB / T 2794 is adopted in this embodiment. GB / T 2794 calculates the viscosity based on the shear stress-shear rate relationship of Newtonian or non-Newtonian fluids, through the torque generated by the rotating rotor in the resin, combined with rotor parameters (such as size, rotation speed). Specifically, the viscosity of the bio-based reinforcing resin can be 17000 mPa·S, 19000 mPa·S, 21000 mPa·S, 23000 mPa·S, 25000 mPa·S, 27000 mPa·S, 29000 mPa·S, 31000 mPa·S, 33000 mPa·S, 35000 mPa·S, 37000 mPa·S, 39000 mPa·S, 41000 mPa·S, 43000 mPa·S, 45000 mPa·S, 47000 mPa·S.

[0101] In some embodiments, the pyrolysis products of the lignin include acetic acid, 4-vinyl-2-methoxyphenol, 2,3-dihydrobenzofuran, 2-methoxy-4-methylphenol, and guaiacol. The mass percentages of acetic acid, 4-vinyl-2-methoxyphenol, 2,3-dihydrobenzofuran, 2-methoxy-4-methylphenol, and guaiacol in the pyrolysis products of the lignin are 0-13%, 5-15%, 1-9%, 1-7%, and 1-2% respectively. Preferably, the mass percentages of acetic acid, 4-vinyl-2-methoxyphenol, 2,3-dihydrobenzofuran, 2-methoxy-4-methylphenol, and guaiacol in the pyrolysis products of the lignin are 10-13%, 10-13%, 3-6%, 3-4%, and 1-2% respectively.

[0102] In some embodiments, the pyrolysis conditions are: temperature 400 °C, time 0.2 min.

[0103] In some embodiments, the lignin is obtained by extraction from plant straws. The plant straws are selected from one or more of straws of gramineous crops, leguminous crops, tuber crops, oil crops, fiber crops, and agricultural product processing by-products. Preferably, the plant straws are selected from one or more of wheat, rice straw, reed, corn, and soybeans.

[0104] In some embodiments, the rosin or its derivatives are selected from one or more of rosin, tall oil rosin, maleic rosin, glycerol rosin ester, polymerized rosin, and hydrogenated rosin. The plant oil modifier is selected from one or more of tall oil, tung oil, linseed oil, soybean oil, and vegetable oil fatty acid.

[0105] In some embodiments, a rubber composition comprises, by weight, 90-110 parts of natural rubber, 60-70 parts of carbon black, 3-5 parts of zinc oxide, 1-3 parts of stearic acid, 2-4 parts of antioxidant, 10-14 parts of bio-based reinforcing resin, 1-3 parts of processing oil, 3-5 parts of insoluble sulfur, and 2-3.5 parts of accelerator. Preferably, it comprises, by weight, 100 parts of natural rubber, 65 parts of carbon black, 4 parts of zinc oxide, 2 parts of stearic acid, 3 parts of antioxidant, 12 parts of bio-based reinforcing resin, 2 parts of processing oil, 4 parts of insoluble sulfur, and 2.7 parts of accelerator.

[0106] In some embodiments, the antioxidant is selected from one or two of 6PPD and RD (TMQ). The accelerator is selected from one or more of NS, CTP, and HMT.

[0107] The present application will be further described below in conjunction with specific embodiments.

[0108] Bio-based reinforcing resin

[0109] Industrial-grade cashew nut shell liquid comes from Jinan Huamao Chemical Co., Ltd., with a content of 99%.

[0110] Rosin comes from Henan Wanshan New Material Technology Co., Ltd., with an effective ingredient content of 99%, brand name gum rosin, acid value / (mgKOH / g) 164, softening point (Ring and Ball method) / °C ≥ 74, ethanol-insoluble matter / % ≤ 0.04, ash content / % ≤ 0.04, CAS 8050-09-7.

[0111] Industrial-grade tung oil comes from Jinan Qinghai Chemical Co., Ltd., with a content of 99%.

[0112] Industrial tall oil comes from Hefeng New Energy Co., Ltd., with a content of 99%.

[0113] Vegetable oleic acid comes from Shandong Hengshuo Chemical Co., Ltd., with an effective ingredient content of 99.9%, density 0.89 g / cm 3 , CAS No. 112-80-1.

[0114] Exxon 5600 petroleum resin from the United States, solid content 99%, brand name 5600, effective ingredient content 99%, molecular weight 800, viscosity 850 cp.

[0115] Lignin:

[0116] The biomass raw material is crushed to a particle size of 1 - 3 cm, and acid hydrolysis is carried out using an organic acid solution containing 40% formic acid, 35% acetic acid, and the balance water. The acid hydrolysis temperature is 100 °C, the reaction time is 150 min, the solid-liquid mass ratio of the organic acid to the plant straw is 1:10. After solid-liquid separation, the reaction solution is obtained, and vacuum concentration is carried out. Formic acid and acetic acid are evaporated to obtain a concentrated solution. The concentrated solution is diluted with water, and the volume ratio of water to the concentrated solution is 3:1. After stirring at 77 °C for 2 - 3 h for water washing and de-esterification, the required lignin is obtained. The biomass raw material is selected from wheat straw, corn straw, reed, masson pine (coniferous plant), populus tomentosa (broad-leaved plant), as shown in Table 1 specifically.

[0117] Table 1 Preparation of lignin

[0118] Biomass raw material Wheat straw Soybean straw Reed Masson pine Chinese white poplar Lignin Lignin 1# Lignin 2# Lignin 3# Lignin 4# Lignin 5#

[0119] The obtained lignin is pyrolyzed using a pyrolysis furnace (EGA / PY-3030D, Frontier, Japan), and its main components and contents are analyzed.

[0120] Instrumentation: Mass spectrometer, 5977B GC / MSD (Agilent, USA); Gas chromatograph, 7890B (Agilent, USA).

[0121] Detection conditions:

[0122] 1. Pyrolysis conditions

[0123] Pyrolysis temperature: 400 °C; pyrolysis time: 0.2 min.

[0124] 2. Gas phase conditions

[0125] Inlet temperature: 300 °C; split ratio: 80:1.

[0126] Oven:

[0127] Heating rate (℃ / min) Temperature (℃) Holding time (min) / 45 5 10 280 60

[0128] 3. Mass spectrometry conditions

[0129] Transfer line temperature: 280 °C; ion source temperature: 230 °C; quadrupole temperature: 150 °C.

[0130] The results are shown in Table 2.

[0131] Table 2 Lignin composition analysis

[0132]

[0133] As can be seen from Table 2, the main components of lignin 1#, lignin 2#, and lignin 3# used in this application are acetic acid, 4-vinyl-2-methoxyphenol, 2,3-dihydrobenzofuran, 2-methoxy-4-methylphenol, and guaiacol.

[0134] Example 1

[0135] In a four-necked flask, add 100 g of lignin 1# and 500 g of cashew shell oil, heat up to 60 °C, stir and keep the temperature constant for 30 min, then add an acidic catalyst (oxalic acid), stir and heat up to 95 °C for reaction. After completion, heat up and start atmospheric distillation until the temperature reaches 155 °C, slowly evacuate to a pressure of -0.098 to -0.1 MPa to remove a small amount of small molecule organic substances and water in the reaction system. Heat up to 180 °C, add 10 g of rosin and 7 g of tung oil, and when the viscosity reaches 18500 mPa·S, add an appropriate amount of alkaline substance (sodium hydroxide) to neutralize the acidic catalyst, and release the material in the flask to cool to obtain the required liquid bio-based reinforcing resin.

[0136] Among them, the mass percentage contents of acetic acid, 4-vinyl-2-methoxyphenol, 2,3-dihydrobenzofuran, 2-methoxy-4-methylphenol, and guaiacol in the pyrolysis products of lignin are: 12.56%, 10.98%, 5.29%, 3.80%, and 1.42% respectively.

[0137] Example 2

[0138] The preparation process is the same as that of Example 1, except that tall oil is used as the vegetable oil modifier. Specifically: heat up to 180 °C, add 10 g of rosin and 7 g of tall oil, and when the reaction reaches a viscosity of 19000 mPa·S, add an appropriate amount of alkaline substance (sodium hydroxide) to neutralize the acidic catalyst, and release the material in the flask and cool it to obtain the required liquid bio-based reinforcing resin.

[0139] Example 3

[0140] The preparation process is the same as that of Example 1, except that oleic acid is used as the vegetable oil modifier. Specifically: heat up to 180 °C, add 10 g of rosin and 7 g of oleic acid, and when the reaction reaches a viscosity of 18705 mPa·S, add an appropriate amount of alkaline substance (sodium hydroxide) to neutralize the acidic catalyst, and release the material in the flask and cool it to obtain the required liquid bio-based reinforcing resin.

[0141] Example 4

[0142] The preparation process is the same as that of Example 1, except that lignin 2# is used.

[0143] Example 5

[0144] The preparation process is the same as that of Example 1, except that lignin 3# is used.

[0145] Example 6

[0146] In a four-necked flask, add 100 g of lignin 2# and 500 g of cashew nut shell oil, heat up to 55 °C, stir and keep it at a constant temperature for 30 min, then add an acidic catalyst (phosphoric acid), stir and heat up to 90 °C for reaction. After completion, heat up and start atmospheric distillation until the temperature reaches 150 °C, slowly evacuate to a pressure of -0.098 to -0.1 MPa to remove a small amount of small molecule organic substances and moisture in the reaction system. Heat up to 170 °C, add 9 g of rosin and 5 g of tung oil, and when the reaction reaches a viscosity of 36500 mPa·s, add an appropriate amount of alkaline substance (potassium hydroxide) to neutralize the acidic catalyst, and release the material in the flask and cool it to obtain the required liquid bio-based reinforcing resin.

[0147] Among them, the mass percentage contents of acetic acid, 4-vinyl-2-methoxyphenol, 2,3-dihydrobenzofuran, 2-methoxy-4-methylphenol, and guaiacol in the pyrolysis products of lignin are: 11.52%, 11.21%, 3.89%, 4.01%, and 1.28% respectively.

[0148] Example 7

[0149] In a four-necked flask, add 100 g of lignin 3#, 600 g of cashew shell oil, heat up to 65 °C, stir and keep the temperature constant for 30 min, then add an acidic catalyst (hydrochloric acid), stir and heat up to 100 °C for reaction. After completion, heat up and start atmospheric distillation until the temperature reaches 160 °C, slowly evacuate to a pressure of -0.098 to -0.1 MPa to remove a small amount of small-molecule organic substances and water in the reaction system. Heat up to 190 °C, add 10 g of rosin and 7 g of tung oil, and when the viscosity reaches 39800 mPa·s, add an appropriate amount of alkaline substance (sodium carbonate) to neutralize the acidic catalyst, and release the material in the flask and cool it to obtain the required liquid bio-based reinforcing resin.

[0150] Among them, the mass percentage contents of acetic acid, 4-vinyl-2-methoxyphenol, 2,3-dihydrobenzofuran, 2-methoxy-4-methylphenol, and guaiacol in the pyrolysis products of lignin are: 10.56%, 12.33%, 4.11%, 3.23%, and 1.87%, respectively.

[0151] Comparative Example 1

[0152] Adopt the well-known synthesis process of modified phenolic reinforcing resin. Add 500 g of phenol and 150 g of cashew shell oil to a four-necked flask, heat up to 95 °C, add an acidic catalyst (oxalic acid) for reaction, add 300 g of liquid formaldehyde (37 wt%) after about 60 minutes, perform atmospheric distillation until the temperature reaches 155 °C, slowly evacuate to a pressure of -0.098 to -0.1 MPa to remove a small amount of small-molecule organic substances and water in the reaction system, add an appropriate amount of alkaline substance for neutralization, and release the material in the flask and cool it to obtain cashew shell oil-modified phenolic reinforcing resin.

[0153] Comparative Example 2

[0154] The preparation process is the same as that of Example 1, except that lignin 4# is used.

[0155] Comparative Example 3

[0156] The preparation process is the same as that of Example 1, except that lignin 5# is used.

[0157] Comparative Example 4

[0158] The preparation process was the same as that of Example 1, except that tung oil and cashew shell oil were substituted for each other. Specifically: In a four-necked flask, 100 g of lignin 1# and 500 g of tung oil were added, and the temperature was raised to 60 °C. After stirring and keeping the temperature constant for 30 min, an acidic catalyst (oxalic acid) was added, and the temperature was raised to 95 °C with stirring for reaction. After completion, the temperature was raised and atmospheric distillation was started until the temperature reached 155 °C, and the vacuum was slowly increased to a pressure of -0.098 to -0.1 MPa to remove a small amount of small-molecule organic substances and water in the reaction system. The temperature was raised to 180 °C, 10 g of rosin and 7 g of cashew shell oil were added, and when the viscosity reached 18500 mPa·S during the reaction, an appropriate amount of alkaline substance (sodium hydroxide) was added to neutralize the acidic catalyst, and the material in the flask was discharged and cooled to obtain the required liquid bio-based reinforcing resin.

[0159] Among them, the mass percentage contents of acetic acid, 4-vinyl-2-methoxyphenol, 2,3-dihydrobenzofuran, 2-methoxy-4-methylphenol, and guaiacol in the pyrolysis product of lignin were: 12.56%, 10.98%, 5.29%, 3.80%, and 1.42%, respectively.

[0160] Comparative Example 5

[0161] The preparation process was the same as that of Example 1, except that petroleum resin was used to replace rosin. Specifically: In a four-necked flask, 100 g of lignin 1# and 500 g of cashew shell oil were added, and the temperature was raised to 60 °C. After stirring and keeping the temperature constant for 30 min, an acidic catalyst (oxalic acid) was added, and the temperature was raised to 95 °C with stirring for reaction. After completion, the temperature was raised and atmospheric distillation was started until the temperature reached 155 °C, and the vacuum was slowly increased to a pressure of -0.098 to -0.1 MPa to remove a small amount of small-molecule organic substances and water in the reaction system. The temperature was raised to 180 °C, 10 g of petroleum resin and 7 g of tung oil were added, and when the viscosity reached 18500 mPa·S during the reaction, an appropriate amount of alkaline substance (sodium hydroxide) was added to neutralize the acidic catalyst, and the material in the flask was discharged and cooled to obtain the required liquid bio-based reinforcing resin.

[0162] Among them, the mass percentage contents of acetic acid, 4-vinyl-2-methoxyphenol, 2,3-dihydrobenzofuran, 2-methoxy-4-methylphenol, and guaiacol in the pyrolysis product of lignin were: 12.56%, 10.98%, 5.29%, 3.80%, and 1.42%, respectively.

[0163] The physical and chemical indexes of the reinforcing resins of Examples 1 to 7 and Comparative Examples 1 to 5 were tested, and the method was as follows:

[0164] 1) Free phenol content: It was detected according to ISO 8974:2002 "Plastics - Phenolic resins - Determination of residual phenols by gas chromatography".

[0165] 2) Softening point: Tested in accordance with the national standard GB / T 9284.1-2015 "Determination of the softening point of binders for paints and varnishes".

[0166] 3) Bio-based carbon content: Tested in accordance with ASTM D6866-24 "Standard Test Method for Determining the Biobased Content of Solid, Liquid, and Gaseous Samples Using Radiocarbon Analysis".

[0167] 4) Viscosity: Tested in accordance with the national standard GB / T 2794-2013 "Determination of the viscosity of adhesives".

[0168] The test results are shown in Table 3.

[0169] Table 3 Physical and chemical indexes of reinforcing resin

[0170] Sample Free phenol / % Softening point / ℃ Viscosity / mPa·S Bio-based carbon content / % Example 1 0 / 18500 100 Example 2 0 / 19000 100 Example 3 0 / 18705 100 Example 4 0 / 21300 100 Example 5 0 / 24310 100 Example 6 0 / 36500 100 Example 7 0 / 39800 100 Comparative example 1 0.61 96.4 / 27 Comparative example 2 0 / 17200 100 Comparative example 3 0 / 17350 100 Comparative example 4 0 / 18055 100 Comparative example 5 0 / 18211 98

[0171] Rubber

[0172] Preparation raw materials: Natural rubber, 3L, Vietnam; Carbon black N330, Jiangxi Black Cat Carbon Black Co., Ltd.; Zinc oxide, Shijiazhuang Shengpeng Chemical Co., Ltd.; Stearic acid, Jiangsu Jinqiao Oil Technology Co., Ltd.; Antioxidant 6PPD, Antioxidant RD, HMT, Ruiyuantong Chemical Co., Ltd.; Processing oil, P50, Total Company; Antioxidant RD, Jiangsu Shengao Chemical Co., Ltd.; Insoluble sulfur HDOT 20, Flexsys America L.P.; Accelerator NS, Shandong Shangshun Chemical Co., Ltd.; Accelerator CTP, Yanggu Huatai.

[0173] Instrumentation: Rubber Processing Analyzer (RPA), Alpha Technologies USA; 1.0L Internal Mixer, Shanghai Kechuang; Laboratory Small Open Mill, GOTZWILER; Plate Vulcanizer, GOTZWILER; Electronic Servo Tensile Tester, GOTZWILER; Rotorless Rheometer, GOTZWILER; Dynamic Mechanical Analyzer (DMA), Mettler Toledo.

[0174] According to the common triangle strip formula of tires shown in Table 4, put 100g of natural rubber into the internal mixer for plasticizing for 30s, then add 39g of carbon black N330, 4g of zinc oxide, 2g of stearic acid, 1.5g of antioxidant 6PPD, 1.5g of antioxidant RD (TMQ), and 12g of the resin obtained from the example or comparative example into the internal mixer and mix for 30s. Then add 2g of processing oil and 26g of carbon black N330 into the internal mixer and mix until the temperature reaches 160 - 170 °C, then discharge the rubber. Then transfer the obtained mixed rubber to the open mill, add 4g of insoluble sulfur, 1.2g of accelerator NS, 0.3g of accelerator CTP, 1.2g of accelerator HMT, mix well by large triangle wrapping and then take out the sheet to obtain a mixed rubber with a thickness of about 2.2mm.

[0175] Table 4 Rubber formula

[0176]

[0177]

[0178]

[0179] The rubber properties of Examples 8 to 16 and Comparative Examples 6 to 10 were tested. Test methods:

[0180] GB / T 528-2009, Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber;

[0181] GB / T 16584-1996, Determination of vulcanization characteristics of rubber by non-rotor vulcanizer;

[0182] GBT 531.1-2008, Indentation hardness test method for vulcanized rubber or thermoplastic rubber (Shore hardness method).

[0183] The results are shown in Tables 5 and 6.

[0184] Table 5 Mooney and vulcanization characteristics of rubber compositions

[0185]

[0186] Table 6 Mechanical properties of rubber compositions (150 °C × 40 min)

[0187]

[0188]

[0189] Based on the data analysis of Tables 5 and 6, the following conclusions can be clearly drawn:

[0190] In Examples 8 to 16, the rubber compositions used are completely composed of 100% bio-based reinforcing resin. Compared with Comparative Example 6, the rubber compositions in these examples show a significantly reduced Mooney viscosity, which can be reduced by about 20%. At the same time, the MH (maximum torque) value of the rubber compound is also relatively low, which directly reflects a significant improvement in the processing performance of the rubber compound. Due to the reduction of Mooney viscosity, the energy consumption during the processing will also be correspondingly reduced, which is beneficial to improving production efficiency and reducing costs. As the viscosity of the bio-based liquid reinforcing resin increases, the MH of the rubber compound shows an upward trend. When the viscosity is greater than 36000, the MH of the rubber compound is close to that of the conventional reinforcing resin.

[0191] In addition, the rubber compositions in Examples 8 to 16 also exhibited an extension of T5 (initial scorch time) and T35 (mid-term scorch time), as well as a shortening of T90 (optimum cure time). This combination of characteristics indicates that during the vulcanization process, the rubber composition using 100% bio-based reinforcing resin not only has excellent processing safety and can effectively prevent the occurrence of early scorching, but also has a fast vulcanization speed and high vulcanization efficiency in the later stage, which is beneficial to shortening the production cycle and improving product quality.

[0192] In terms of mechanical properties, compared with Comparative Example 6, the rubber compositions in Examples 8 to 16 also performed excellently. They showed good tensile strength, tear strength, and 300% modulus at elongation. As the viscosity of the bio-based liquid reinforcing resin increased, the hardness of the rubber compound tended to increase. When the viscosity was greater than 18,500, the hardness of the rubber compound reached that of the conventional thermoplastic cashew shell oil-modified phenolic reinforcing resin. The improvement of these properties further verified the effectiveness and advantages of the 100% bio-based reinforcing resin in the rubber composition.

[0193] Particularly noteworthy is Example 12, which combines the bio-based reinforcing resin in Example 1 and the cashew shell oil-modified phenolic reinforcing resin in Comparative Example 1. Compared with Comparative Example 6, the rubber composition in Example 12 also showed a decrease in Mooney viscosity, a decrease in MH value, an extension of T5 and T35 scorch times, and a shortening of t90 vulcanization time. More importantly, this example also significantly improved the tear strength and 300% modulus at elongation of the rubber composition. This result indicates that by reasonably matching the bio-based reinforcing resin and the cashew shell oil-modified phenolic reinforcing resin in this application, not only can the performance of the cashew shell oil-modified phenolic reinforcing resin be effectively improved, but also the overall performance of the rubber composition can be further enhanced, providing a broader selection space for the production and application of rubber products.

[0194] In Comparative Examples 7 and 8, the bio-based reinforcing resin used was softwood lignin and hardwood lignin. Compared with the rubber compositions of the bio-based reinforcing resin in Examples 8 to 11 and Examples 13 to 16, it showed a shorter scorch time and a faster vulcanization speed, which was not conducive to processing safety. The heat generation of the rubber compound was slightly higher, and the anti-aging performance decreased slightly.

[0195] After the bio-based material tung oil replaced the cashew shell oil in Comparative Example 9, the density of the rubber compound decreased significantly, and the properties such as MH and hardness were very different from those of the rubber compounds in Examples 8 to 16.

[0196] In Comparative Example 10, when the petrochemical material petroleum resin was used to replace the bio-based material, because the addition amount was small, it had little effect on the mechanical properties and processing of the rubber compound, but the heat generation performance of the rubber compound decreased slightly.

[0197] Although the above embodiments of the present application have been described, the present application is not limited to the above specific embodiments and application fields. The above specific embodiments are merely illustrative and guiding, rather than restrictive. Those of ordinary skill in the art can also make many forms under the inspiration of this specification and without departing from the scope protected by the claims of the present application, and these all fall within the scope of protection of the present application.

Claims

1. A bio-based reinforcing resin, wherein, The raw materials for preparing the bio-based reinforcing resin include lignin, cashew shell oil, rosin or its derivatives, and vegetable oil modifiers.

2. The bio-based reinforcing resin according to claim 1, wherein the preparation raw materials include the following components in parts by weight: 2 - 100 parts of lignin, 500 - 600 parts of cashew shell oil, 0 - 10 parts of rosin or its derivatives, 0 - 7 parts of vegetable oil modifiers.

3. The bio-based reinforcing resin according to claim 1, wherein the viscosity of the bio-based reinforcing resin is 17,000 - 47,000 mPa·S.

4. The bio-based reinforcing resin according to claim 1, wherein the pyrolysis products of the lignin include acetic acid, 4-vinyl-2-methoxyphenol, 2,3-dihydrobenzofuran, 2-methoxy-4-methylphenol, and guaiacol; Preferably, the pyrolysis conditions are: temperature 400 °C, time 0.2 min.

5. The bio-based reinforcing resin according to claim 1, wherein the rosin or its derivatives are selected from one or more of rosin, tall oil rosin, maleic rosin, rosin glyceride, polymerized rosin, and hydrogenated rosin.

6. The bio-based reinforcing resin according to claim 1, wherein the vegetable oil modifiers are selected from one or more of tall oil, tung oil, linseed oil, soybean oil, and vegetable fatty acid.

7. The preparation method of the bio-based reinforcing resin according to any one of claims 1 to 6, comprising: The lignin, cashew shell oil, rosin or its derivatives, and vegetable oil modifiers are polymerized under the action of an acidic catalyst to obtain the bio-based reinforcing resin.

8. According to the preparation method of claim 7, the lignin and cashew shell oil are mixed evenly, and an acidic catalyst is added for catalytic polycondensation reaction; the rosin or its derivatives and vegetable oil modifiers are added for further reaction to obtain the bio-based reinforcing resin; Preferably, the lignin and cashew shell oil are stirred and mixed at 55 - 65 °C; Preferably, the reaction temperature of the catalytic polycondensation is 90 - 100 °C; Preferably, the temperature of the further reaction is 165 - 185 °C.

9. A rubber composition comprising the bio-based reinforcing resin according to any one of claims 1 - 6 or the bio-based reinforcing resin obtained by the preparation method according to any one of claims 7 - 8.

10. The application of the bio-based reinforcing resin according to any one of claims 1 - 6 or the bio-based reinforcing resin obtained by the preparation method according to any one of claims 7 - 8 in rubber products.

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