Modified phenol-formaldehyde resin, method for producing the same, and rubber composition

Abstract

The application discloses a modified phenolic resin and a preparation method thereof, and a rubber composition, and belongs to the rubber material field. The preparation method of the modified phenolic resin comprises the following steps: performing one-stage condensation reaction on a phenolic compound and a first-stage aldehyde, and then performing one-stage dehydration treatment to obtain a first-stage resin; and performing two-stage condensation reaction on the first-stage resin, a second-stage aldehyde and lignin to obtain the modified phenolic resin. The preparation method provided in the application embodiment adds lignin to modify the phenolic resin, realizes effective utilization of the natural resource of lignin, and enables the modified phenolic resin to better improve the adhesive property while keeping good mechanical property and vulcanization property when being applied to rubber and other reinforcing adhesive materials. Meanwhile, the specific step-by-step preparation process effectively improves the reaction activity and efficiency of the lignin, can improve the modification effect, and can effectively reduce the free phenol content in the modified phenolic resin, which is beneficial to better application of the modified phenolic resin.

Description

Modified phenolic resin and its preparation method, and rubber composition Technical Field

[0001] This application relates to the field of rubber materials, and more specifically, to a modified phenolic resin, a method for preparing the same, and a rubber composition. Background Technology

[0002] Phenolic resin is a common component in reinforcing adhesives such as rubber compositions, and it has a certain influence on the mechanical properties, vulcanization properties, and adhesive properties of the materials. Among these, adhesive properties are particularly important for the application of phenolic resin in rubber-based reinforcing adhesives. By modifying phenolic resin, adhesive properties can be effectively improved while maintaining good mechanical and vulcanization properties, which is beneficial for the better application of phenolic resin. Summary of the Invention

[0003] The purpose of this application is to provide a modified phenolic resin, a method for preparing the same, and a rubber composition. The modified phenolic resin obtained can be applied to reinforcing adhesive materials such as rubber, and can effectively improve the adhesive properties while maintaining good mechanical and vulcanization properties.

[0004] The embodiments of this application are implemented as follows:

[0005] In a first aspect, embodiments of this application provide a method for preparing a modified phenolic resin, comprising:

[0006] A phenolic compound and an aldehyde are subjected to a condensation reaction, followed by a dehydration process to obtain a resin.

[0007] A modified phenolic resin is obtained by undergoing a two-stage condensation reaction of a primary resin, a secondary aldehyde, and lignin. The method for preparing the modified phenolic resin provided in this application has the following beneficial effects:

[0008] (1) Using natural materials such as lignin as modification raw materials can realize the effective use of natural resources and help reduce modification costs.

[0009] (2) Phenolic resin is modified with lignin. The resulting modified phenolic resin is applied to reinforcing adhesive materials such as rubber compositions. Compared with unmodified phenolic resin, the material exhibits comparable or even better mechanical and vulcanization properties. Furthermore, the adhesive properties before and after aging are significantly improved. Therefore, the modified phenolic resin prepared by this method can be well applied to reinforcing adhesive materials such as rubber compositions.

[0010] (3) A first-stage condensation reaction is carried out, followed by a first-stage dehydration treatment, and then lignin is added in the second-stage condensation reaction for modification. The first-stage dehydration treatment results in a lower water content during the second-stage condensation reaction, and compared with the first-stage condensation reaction, the molecular weight of the second-stage condensation reaction is increased, the softening point is raised, and the required reaction temperature is relatively higher. Therefore, compared with direct addition of lignin for reaction modification, the second-stage condensation reaction, due to its relatively lower water content and higher reaction temperature, can improve the reactivity and efficiency of lignin, thus improving the modification effect. At the same time, it is beneficial to reduce the free phenol content in the modified phenolic resin, and to improve the mechanical properties and vulcanization properties of reinforcing adhesives such as rubber compositions.

[0011] In some alternative embodiments, the phenolic compound includes one or more of phenol, cashew nut oil, and styrene-modified phenol;

[0012] and / or

[0013] During the two-stage condensation reaction of a primary resin, a secondary aldehyde, and lignin, bio-based raw materials are also added to participate in the two-stage condensation reaction. These bio-based raw materials include one or more of cashew phenol, cashew oil, and rice bran oil.

[0014] In the above technical solution, the first-stage condensation reaction uses specific phenolic compounds, which can effectively carry out the condensation reaction. Furthermore, when the phenolic compounds in the first-stage condensation reaction include cashew nut shell extract, cashew oil, etc., and / or when bio-based raw materials are added in the second-stage condensation reaction, cashew nut shell extract, cashew oil, rice bran oil, etc., can be used to modify the phenolic resin. When the modified phenolic resin is applied to reinforcing adhesive materials such as rubber compositions, it is beneficial to further improve at least one of the material's mechanical properties, vulcanization properties, and adhesive properties.

[0015] In some alternative embodiments, at least one of cashew phenol and cashew oil is added during the primary condensation reaction of the phenolic compound and the primary aldehyde, and / or during the secondary condensation reaction of the primary resin, the secondary aldehyde and the lignin.

[0016] Optionally, the total amount of cashew phenol and cashew oil in the reaction raw materials is 5% to 50% by mass.

[0017] In the above technical solution, at least one of cashew phenol and cashew oil is added during the first-stage condensation reaction and / or the second-stage condensation reaction, which can modify the phenolic resin. When the modified phenolic resin is applied to reinforcing adhesive materials such as rubber compositions, it is beneficial to further improve at least one of the mechanical properties, vulcanization properties and adhesive properties of the material.

[0018] Optionally, adjusting the total amount of cashew nut phenol and cashew oil in the raw materials to meet a specific ratio can achieve a better modification effect on phenolic resin; at the same time, ensuring a suitable aldehyde-phenol ratio during the reaction process is beneficial for better control of the softening point and reaction process of phenolic resin.

[0019] In some alternative implementations, at least one of the following conditions (a1) and (a2) is met;

[0020] (a1) In the process of condensing a phenolic compound and a aldehyde, the molar ratio of the aldehyde to the phenolic compound is 0.6 to 0.8:1;

[0021] (a2) The amount of lignin used in the reaction raw materials is 5% to 40% by mass.

[0022] In the above technical solution, regarding condition (a1), satisfying a suitable aldehyde-phenol ratio during a condensation reaction is beneficial for better control of the softening point and reaction process of the resin in a certain stage; regarding condition (a2), adjusting the amount of lignin in the raw materials to meet a specific proportion can achieve a better modification effect on phenolic resin.

[0023] In some alternative implementations, at least one of the following conditions (b1) to (b3) is satisfied;

[0024] (b1) The softening point of the resin is 60℃~90℃;

[0025] (b2) The softening point of the modified phenolic resin is 90℃~130℃;

[0026] (b3) The weight-average molecular weight of the modified phenolic resin is 2500 to 6000.

[0027] In the above technical solution, controlling the resin and modified phenolic resin to have specific softening points and specific weight-average molecular weights is beneficial to better control the reaction process and enable the obtained modified phenolic resin to be better applied in reinforcing adhesive materials such as rubber compositions.

[0028] In some alternative implementations, at least one of the following conditions (c1) and (c2) is met;

[0029] (c1) In the process of condensing phenolic compounds and a aldehyde, the condensation reaction is carried out under reflux, the reaction temperature is 70℃~100℃, and the reaction time is 0.5h~3h.

[0030] (c2) During the two-stage condensation reaction of the first-stage resin, the second-stage aldehyde and lignin, the two-stage condensation reaction is carried out under reflux, the reaction temperature is 100℃~150℃, and the reaction time is 0.5h~3h.

[0031] In the above technical solution, the first-stage condensation reaction and the second-stage condensation reaction each meet specific reaction temperatures and reaction times, ensuring that the condensation reactions of each stage are completed well.

[0032] In some alternative implementations, at least one of the following conditions (d1) and (d2) is met;

[0033] (d1) During the first stage of dehydration, a heating distillation method is used, with a temperature of 100℃~150℃;

[0034] (d2) After the process of two-stage condensation reaction of resin, aldehyde and lignin, a second-stage dehydration treatment is also included; in the second-stage dehydration treatment, a heated distillation method is adopted, with a temperature of 150℃~175℃.

[0035] In the above technical solution, the temperature of the first stage of dehydration is slightly higher than the reaction temperature of the first stage of condensation reaction, and the temperature of the second stage of dehydration is slightly higher than the reaction temperature of the second stage of condensation reaction, so as to ensure that the dehydration of each stage is completed well.

[0036] In some alternative embodiments, the primary condensation reaction of the phenolic compound and the primary aldehyde is carried out under acidic conditions containing an acid catalyst; after the secondary condensation reaction of the primary resin, the secondary aldehyde, and the lignin, an alkaline neutralization treatment is also included.

[0037] Optionally, the acid catalyst includes one or more of benzenesulfonic acid, p-toluenesulfonic acid, dodecylbenzenesulfonic acid, and oxalic acid;

[0038] Optionally, the reagents used for the base neutralization treatment include one or more of diethylamine, triethylamine, diethanolamine, triethanolamine and 1,8-diazabicyclo[5.4.0]undec-7-ene.

[0039] In the above technical solution, the acidic conditions containing the acid catalyst are conducive to the efficient and complete conduct of the first-stage condensation reaction, and the acid in the system is treated by alkali neutralization after the second-stage condensation reaction.

[0040] Optionally, selecting a specific type of acid catalyst can facilitate better catalysis of a single-stage condensation reaction.

[0041] Optionally, a specific organic base neutralizing agent can be selected to react the acid in the system to generate a small amount of specific organic salt. These specific organic salts will not precipitate in the phenolic resin, thus reducing the pollution to the phenolic resin.

[0042] Secondly, this application provides a modified phenolic resin, which is prepared using the preparation method described in the above embodiments.

[0043] Thirdly, embodiments of this application provide a rubber composition comprising the modified phenolic resin as described in the above embodiments;

[0044] Optionally, the rubber composition includes standard rubber, reinforcing filler, zinc oxide, antioxidant, methylene donor, sulfur, accelerator, cobalt salt and modified phenolic resin; further optionally, the reinforcing filler is carbon black or a combination of carbon black and silica;

[0045] Optionally, the rubber composition is used in a tire part, the tire part including one or more of the following: a rubber ply of the tire, a tread of the tire, a carcass reinforcement of the tire, and a tread rubber of the tire. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0047] It should be noted that, in this document, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0048] In this application, "and / or", such as "feature 1 and / or feature 2", refers to three cases: feature 1 alone, feature 2 alone, and feature 1 plus feature 2.

[0049] In addition, in the description of this application, unless otherwise stated, "one or more" means two or more; the range of "numerical value a to numerical value b" includes the two endpoints "a" and "b"; and "unit of measurement" in "numerical value a to numerical value b + unit of measurement" represents the "unit of measurement" of both "numerical value a" and "numerical value b".

[0050] Petrochemical products are closely related to people's lives, bringing convenience and enjoyment. However, as a non-renewable resource, petrochemical resources will eventually be depleted. Biomass products, as a renewable resource, are an important direction for future industrial development. Lignin, cashew oil, cashew phenol, and other natural organic polymers with wide sources and great application value have important application value in industrial production.

[0051] Lignin is a class of aromatic polymers widely found in plants, second only to cellulose in abundance. Its active groups, such as side chains and aromatic rings, can react with aldehydes, phenols, or other monomers to form derivatives. Industrial lignin mainly originates from the paper and biomass refining industries. Globally, 50 million tons of industrial lignin are produced annually from pulp and paper production, but only a small portion is effectively utilized. The majority is burned as low-value fuel or directly emitted, resulting in significant resource waste and severe environmental pollution. Therefore, the efficient and high-value utilization of industrial lignin has significant economic, environmental, and social implications. Research has also found that lignin can serve as a natural reinforcing agent in the rubber industry, effectively reducing heat generation and significantly decreasing volumetric wear. Therefore, lignin's unique thermoplastic structure can partially replace phenol or phenolic resins.

[0052] Cardanol is a bio-based raw material extracted from natural cashew nut shell oil. It is a renewable resource with abundant sources. Its composition includes cardanol monophenol and cardanol diphenol. Due to the long alkyl chains located at the meta position of the phenolic hydroxyl groups, their structure exhibits high reactivity and can replace or partially replace phenol in the manufacture of thermosetting phenolic resins. Specifically, the alkyl chains increase the compatibility between the resin and rubber, thereby promoting the compatibility of the resin and rubber networks. Furthermore, the double bonds on the alkyl chains react with sulfur during rubber vulcanization, chemically linking the resin and rubber networks together. These factors all contribute to improving the modulus, hardness, and wire pull-out force of the rubber compound.

[0053] Based on this, some technical solutions have proposed methods to modify phenolic resins with natural bio-based materials such as lignin or cashew nut shell powder to improve the performance of reinforcing adhesive materials such as rubber compositions. Studies have found that lignin modification is more effective than cashew nut shell powder modification in improving the adhesive properties of materials (e.g., steel wire bonding performance), and this property is crucial for the application of reinforcing adhesive materials such as vulcanized rubber, having significant implications for their practical use. However, lignin modification often suffers from low reactivity and efficiency, resulting in a high content of free phenol in the prepared modified phenolic resin. This high content of free phenol negatively impacts its application in reinforcing adhesive materials such as vulcanized rubber.

[0054] Based on this, this application proposes a method for preparing modified phenolic resin, which modifies the phenolic resin by adding lignin, thereby achieving effective utilization of lignin's natural resources and enabling the modified phenolic resin to better improve the adhesive performance of reinforcing adhesive materials such as rubber compositions; at the same time, by adopting specific step-by-step preparation processes, the reactivity and efficiency of lignin are effectively improved, thereby enhancing the modification effect and effectively reducing the free phenol content in the modified phenolic resin.

[0055] The modified phenolic resin, its preparation method, and the rubber composition of the embodiments of this application are described in detail below.

[0056] In a first aspect, embodiments of this application provide a method for preparing modified phenolic resin, comprising: performing a condensation reaction of a phenolic compound and a first-stage aldehyde, followed by a first-stage dehydration treatment to obtain a first-stage resin; and performing a second-stage condensation reaction of the first-stage resin, a second-stage aldehyde, and lignin to obtain modified phenolic resin.

[0057] The terms "first stage" and "second stage" in a single-stage condensation reaction and a two-stage condensation reaction are used to distinguish between different stages of the condensation reaction. They do not indicate which stage of the condensation reaction is being carried out, nor do they indicate how many times the condensation reaction in that stage has been carried out.

[0058] It should be noted that the phenolic condensation reaction mainly occurs during the first and second stages of the condensation reaction, but other reactions may also occur. The reaction temperature of each stage of the condensation reaction can be selected based on the softening point and reactivity of the raw materials. Since the monomer condenses to form a resin after the first stage of the condensation reaction, the softening point of the raw materials increases and the reactivity decreases. Therefore, the reaction temperature of the second stage of the condensation reaction is, for example, higher than that of the first stage of the condensation reaction.

[0059] The method for preparing modified phenolic resin provided in this application uses natural materials such as lignin as modifying raw materials, which realizes the effective utilization of natural resources and helps to reduce modification costs.

[0060] In the preparation method of this application embodiment, lignin is used to modify phenolic resin. The resulting modified phenolic resin is applied to reinforcing adhesive materials such as rubber compositions. Compared with unmodified phenolic resin, the material exhibits comparable or even better mechanical and vulcanization properties. Furthermore, the relatively higher content of phenolic hydroxyl and methoxy functional groups in lignin effectively enhances the heat aging resistance and adhesive properties of the rubber compound, resulting in a significant improvement in adhesive performance before and after aging. Therefore, the modified phenolic resin prepared by this method can be well applied to reinforcing adhesive materials such as rubber compositions.

[0061] Furthermore, the applicant's research found that lignin has poor solubility in water, tends to agglomerate, and exhibits poor reactivity. In the preparation method of this application's embodiments, a first-stage condensation reaction is performed, followed by a first-stage dehydration treatment, and then lignin is added for modification in a second-stage condensation reaction. The first-stage dehydration treatment results in a lower water content during the second-stage condensation reaction, and compared to the first-stage condensation reaction, the second-stage condensation reaction has a higher molecular weight, a higher softening point, and requires a relatively higher reaction temperature. Therefore, compared to directly adding lignin for reaction modification, the second-stage condensation reaction, due to its relatively lower water content and higher reaction temperature, can improve the reactivity and efficiency of lignin, thus enhancing the modification effect. Simultaneously, it helps reduce the free phenol content in modified phenolic resins and improves the mechanical properties and vulcanization properties of reinforcing adhesives such as rubber compositions.

[0062] In the embodiments of this application, optionally, at least one of cashew phenol and cashew oil is added during the primary condensation reaction of phenolic compounds and a primary aldehyde, and / or during the secondary condensation reaction of a primary resin, a secondary aldehyde, and lignin.

[0063] In other words, the modification can be achieved by introducing at least one of cashew nut phenol and cashew oil in only the first stage of condensation reaction, or by introducing at least one of cashew nut phenol and cashew oil in only the second stage of condensation reaction, or by introducing at least one of cashew nut phenol and cashew oil in both the first stage and the second stage of condensation reaction.

[0064] In the above technical solution, at least one of cashew phenol and cashew oil is added during the first-stage condensation reaction and / or the second-stage condensation reaction, which can modify the phenolic resin. When the modified phenolic resin is applied to reinforcing adhesive materials such as rubber compositions, it is beneficial to further improve at least one of the mechanical properties, vulcanization properties and adhesive properties of the material.

[0065] Furthermore, the total amount of cashew nut phenol and cashew oil in the reaction raw materials accounts for 5% to 50% by mass. Specifically, the total amount of cashew nut phenol and cashew oil in the reaction raw materials can be, for example, but not limited to, any one of 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, and 50%, or a range between any two.

[0066] In the embodiments of this application, the reaction raw materials refer to the types of raw materials used to participate in the condensation reaction in the first-stage condensation reaction and the second-stage condensation reaction, including aldehydes, phenols, lignin, bio-based raw materials, etc., but excluding solvents, catalysts, etc.

[0067] In the above technical solution, adjusting the total amount of cashew phenol and cashew oil in the raw materials to meet a specific ratio can achieve a better modification effect on phenolic resin; at the same time, ensuring a suitable aldehyde-phenol ratio during the reaction process is beneficial for better control of the softening point and reaction process of phenolic resin.

[0068] Regarding a condensation reaction, in some embodiments, the phenolic compound includes one or more of phenol, cashew nut oil, and styrene-modified phenol.

[0069] In the above technical solution, the condensation reaction is carried out using specific phenolic compounds, which can effectively facilitate the condensation reaction. Furthermore, when the phenolic compounds in the condensation reaction include cashew nut oil, cashew nut oil, rice bran oil, etc., the phenolic resin can be modified using cashew nut oil, cashew nut oil, rice bran oil, etc. When the modified phenolic resin is applied to reinforcing adhesive materials such as rubber compositions, it is beneficial to further improve at least one of the material's mechanical properties, vulcanization properties, and adhesive properties.

[0070] Regarding the condensation reaction, in some embodiments, the softening point of the resin stage is 60°C to 90°C. The softening point of the resin stage is, for example, but not limited to, any one of 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, and 90°C, or a range between any two.

[0071] In the above technical solution, controlling a specific softening point of a resin section is beneficial for better control of the reaction process and enables the modified phenolic resin to be better applied in reinforcing adhesive materials such as rubber compositions.

[0072] Furthermore, during the condensation reaction of the phenolic compound and the aldehyde, the molar ratio of the aldehyde to the phenolic compound is 0.6–0.8:1. The molar ratio of the aldehyde to the phenolic compound is, for example, but not limited to, any one of 0.6, 0.67, 0.7, 0.75, and 0.8, or a range between any two.

[0073] In the above technical solution, satisfying a suitable aldehyde-phenol ratio during a condensation reaction is beneficial for better control of the softening point and reaction process of the resin in that stage.

[0074] Furthermore, in the process of a single-stage condensation reaction between a phenolic compound and an aldehyde, the single-stage condensation reaction is carried out under reflux conditions at a temperature of 70℃ to 100℃ and a reaction time of 0.5h to 3h. The reaction temperature is, for example, but not limited to, any one of 70℃, 75℃, 80℃, 85℃, 90℃, 95℃, and 100℃, or a range between any two; the reaction time is, for example, but not limited to, any one of 0.5h, 1h, 1.5h, 2h, 2.5h, and 3h, or a range between any two.

[0075] In the above technical solution, a condensation reaction meets specific reaction temperature and reaction time to ensure that a condensation reaction is completed well.

[0076] In the embodiments of this application, the type of aldehyde is not limited, such as, but not limited to, formaldehyde. Since the condensation reaction can be carried out at a relatively low reaction temperature, liquid formaldehyde is used, for example, for the condensation reaction, because liquid formaldehyde has high reaction efficiency and is less expensive than solid formaldehyde; of course, in other embodiments, solid formaldehyde may also be used for the condensation reaction.

[0077] Regarding the first-stage dehydration process, in some embodiments, the first-stage dehydration process employs heated distillation at a temperature of 100°C to 150°C. The heated distillation temperature during the first-stage dehydration process is, for example, but not limited to, any one of 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, and 140°C, or a range between any two.

[0078] In the above technical solution, the temperature of the first stage of dehydration treatment is slightly higher than the reaction temperature of the first stage of condensation reaction to ensure that the dehydration after the first stage of condensation reaction is completed well.

[0079] Regarding the two-stage condensation reaction, in some embodiments, during the two-stage condensation reaction of the primary resin, the secondary aldehyde, and the lignin, a bio-based raw material is also added to carry out the two-stage condensation reaction together. The bio-based raw material includes one or more of cashew phenol, cashew oil, and rice bran oil.

[0080] In the above technical solution, bio-based raw materials are added to the two-stage condensation reaction, which can modify phenolic resin by using cashew phenol, cashew oil, rice bran oil, etc. When the modified phenolic resin is applied to reinforcing adhesive materials such as rubber compositions, it is beneficial to further improve at least one of the mechanical properties, vulcanization properties and adhesive properties of the material.

[0081] Regarding the two-stage condensation reaction, in some embodiments, the softening point of the modified phenolic resin is 90°C to 130°C. The softening point of the modified phenolic resin is higher than that of the primary resin, for example, but not any one of 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, and 130°C, or any range between two of these values.

[0082] Regarding the two-stage condensation reaction, in some embodiments, the weight-average molecular weight of the modified phenolic resin is 2500–6000. Specifically, the weight-average molecular weight of the modified phenolic resin is, for example, but not limited to, any one of 2500, 3000, 3500, 4000, 4500, 5000, 5500, and 6000, or a range between any two.

[0083] In the above technical solution, controlling the modified phenolic resin to have a specific softening point and / or controlling the modified phenolic resin to have a specific weight-average molecular weight is beneficial to better control the reaction process and enable the obtained modified phenolic resin to be better applied in reinforcing adhesive materials such as rubber compositions.

[0084] Furthermore, during the two-stage condensation reaction of the primary resin, the secondary aldehyde, and lignin, the two-stage condensation reaction is carried out under reflux conditions at a temperature of 100℃ to 150℃ and a reaction time of 0.5h to 3h. The reaction temperature of the second-stage condensation reaction is higher than that of the primary condensation reaction, for example, but not limited to, any one of 100℃, 105℃, 110℃, 115℃, 120℃, 125℃, 130℃, 135℃, 140℃, 145℃, and 150℃, or a range between any two; the reaction time is for example, but not limited to, any one of 0.5h, 1h, 1.5h, 2h, 2.5h, and 3h, or a range between any two.

[0085] In the above technical solution, the two-stage condensation reaction meets specific reaction temperature and reaction time to ensure a better two-stage condensation reaction.

[0086] In the embodiments of this application, the type of aldehyde in the second stage is not limited, such as, but not limited to, formaldehyde. Since the reaction temperature of the second-stage condensation reaction is relatively high, solid formaldehyde is used, for example, to improve the safety of the reaction and to carry out the second-stage condensation reaction.

[0087] Regarding the two-stage condensation reaction, in some embodiments, the amount of lignin used in the reaction raw materials is 5% to 40% by mass. The explanation of the reaction raw materials is as described above, and the mass percentage of lignin used in the reaction raw materials is, for example, but not limited to, any one of 5%, 10%, 15%, 20%, 25%, 30%, 35%, and 40%, or a range between any two.

[0088] In the above technical solution, adjusting the amount of lignin in the raw materials to meet a specific proportion can achieve a better modification effect on phenolic resin.

[0089] Understandably, after the two-stage condensation reaction is completed, some post-processing operations can be carried out as needed, such as drying, purification, and waste disposal.

[0090] As an example, in some embodiments, after the two-stage condensation reaction of the resin, aldehyde, and lignin, a two-stage dehydration treatment is further included; in the two-stage dehydration treatment, a heated distillation method is used, with a temperature of 150°C to 175°C. The heated distillation temperature in the two-stage dehydration treatment is, for example, but not limited to, any one of 150°C, 155°C, 160°C, 165°C, 170°C, and 175°C, or a range between any two.

[0091] In the above technical solution, the temperature of the second-stage dehydration treatment is slightly higher than the reaction temperature of the second-stage condensation reaction, ensuring that the dehydration after the second-stage condensation reaction is completed well.

[0092] It should be noted that, in the embodiments of this application, in addition to the processing conditions and processing steps mentioned in the above embodiments, experimental conditions and steps can also be designed as needed.

[0093] As a first example, a solvent may or may not be used during the preparation process.

[0094] In some embodiments, the condensation reaction between a phenolic compound and an aldehyde is carried out in the presence of a solvent. The solvent includes one or more of toluene, xylene, and ethanol.

[0095] As a second example, the acidity or alkalinity of the system can be adjusted as needed during the preparation process, and a catalyst can be added as needed.

[0096] In some embodiments, the primary condensation reaction of the phenolic compound and the primary aldehyde is carried out under acidic conditions containing an acid catalyst; after the secondary condensation reaction of the primary resin, the secondary aldehyde, and the lignin, an alkali neutralization treatment is further included.

[0097] In the above technical solution, the acidic conditions containing the acid catalyst are conducive to the efficient and complete conduct of the first-stage condensation reaction, and the acid in the system is treated by alkali neutralization after the second-stage condensation reaction.

[0098] The type of acid catalyst is not limited, but optionally, the acid catalyst includes one or more of benzenesulfonic acid, p-toluenesulfonic acid, dodecylbenzenesulfonic acid and oxalic acid.

[0099] In the above technical solutions, selecting a specific type of acid catalyst is beneficial for the better catalysis of a single-stage condensation reaction.

[0100] The type of reagent used for alkali neutralization is not limited. Optionally, the reagent used for alkali neutralization includes one or more of diethylamine, triethylamine, diethanolamine, triethanolamine and 1,8-diazabicyclo[5.4.0]undec-7-ene.

[0101] In the above technical solution, a specific organic base neutralizing agent is selected to react the acid in the system to generate a small amount of specific organic salt. These specific organic salts will not precipitate in the phenolic resin, thus reducing the pollution to the phenolic resin.

[0102] Secondly, this application provides a modified phenolic resin, which is prepared using the preparation method described in the above embodiments.

[0103] The modified phenolic resin provided in this application embodiment is prepared based on the above preparation method and can be well applied to viscous formulations, such as reinforcing adhesive materials like rubber.

[0104] Thirdly, embodiments of this application provide a rubber composition comprising the modified phenolic resin as described in the above embodiments.

[0105] Optionally, the rubber composition includes standard rubber, reinforcing filler, zinc oxide, antioxidant, methylene donor, sulfur, accelerator, cobalt salt and modified phenolic resin; further optionally, the reinforcing filler is carbon black or a combination of carbon black and silica;

[0106] Optionally, the rubber composition is used in a tire part, the tire part including one or more of the following: a rubber ply of the tire, a tread of the tire, a carcass reinforcement of the tire, and a tread rubber of the tire.

[0107] The features and performance of this application will be further described in detail below with reference to the embodiments.

[0108] The names and sources of the raw materials used in the following groups of experiments are shown in Table 1 below.

[0109] Table 1. Names and sources of raw materials

[0110]

[0111]

[0112] I. Preparation of Phenolic Resin

[0113] Example 1

[0114] S1. Add 1.0 mol of phenol, 0.1 mol of cashew phenol, 50 g of toluene, and 1.0 g of p-toluenesulfonic acid to a reaction flask equipped with a stirrer, thermometer, and reflux condenser. Gradually raise the temperature to 95°C, add 0.8 mol of liquid formaldehyde dropwise, and react for 2 hours. Then switch to distillation mode and raise the temperature to 140°C. After dehydration and solvent removal, a first-stage resin with a low softening point of 81.3°C is obtained.

[0115] S2. Change to reflux state, add 30g of lignin, maintain reaction temperature at 140℃, add 3.0g of solid formaldehyde, react for 1h, then change to distillation state, gradually raise the temperature to 165℃, vacuum, add triethylamine to neutralize, and obtain lignin and cashew phenol modified phenolic resin with a softening point of 105.6℃ and a resin weight average molecular weight of 3994.

[0116] Example 2

[0117] S1. Add 1.0 mol of phenol, 50 g of toluene, and 1.0 g of p-toluenesulfonic acid to a reaction flask equipped with a stirrer, thermometer, and reflux condenser. Gradually raise the temperature to 95°C, add 0.70 mol of liquid formaldehyde dropwise, and react for 2 hours. Then, switch to distillation mode and raise the temperature to 140°C. After dehydration and solvent removal, a first-stage resin with a low softening point of 82.4°C is obtained.

[0118] S2. Change to reflux state, add 30g of lignin and 30g of cashew phenol, maintain the reaction temperature at 140℃, add 6.0g of solid formaldehyde, react for 1h, then change to distillation state, gradually raise the temperature to 165℃, vacuum, add triethylamine to neutralize, and obtain lignin and cashew phenol modified phenolic resin with a softening point of 106.4℃ and a resin weight average molecular weight of 4056.

[0119] Example 3

[0120] S1. Add 1.0 mol of styrene-modified phenol, 0.15 mol of cashew phenol, 50 g of xylene, 30 g of deionized water, and 1.5 g of dodecylbenzenesulfonic acid to a reaction flask equipped with a stirrer, thermometer, and reflux condenser. Gradually raise the temperature to 98°C, add 0.72 mol of liquid formaldehyde dropwise, and react for 2 hours. Then, switch to distillation mode, raise the temperature to 150°C, and after dehydration and solvent removal, obtain a first-stage resin with a low softening point of 61.3°C.

[0121] S2. Change to reflux state, add 60g of lignin, maintain reaction temperature at 150℃, add 6.5g of solid formaldehyde, react for 1h, then change to distillation state, gradually raise the temperature to 165℃, vacuum, add triethylamine to neutralize, and obtain lignin and cashew phenol modified phenolic resin with a softening point of 111.2℃ and a resin weight average molecular weight of 4528.

[0122] Example 4

[0123] S1. Add 1.0 mol of styrene-modified phenol, 30 g of water, and 1.0 g of dodecylbenzenesulfonic acid to a reaction flask equipped with a stirrer, thermometer, and reflux condenser. Gradually raise the temperature to 98°C, add 0.72 mol of liquid formaldehyde dropwise, and react for 2 hours. Then, switch to distillation mode, raise the temperature to 130°C, and dehydrate to obtain a first-stage resin with a low softening point of 86.7°C.

[0124] S2. Change to reflux state, add 50g of lignin, maintain reaction temperature at 150℃, add 4.0g of solid formaldehyde, react for 1h, then change to distillation state, gradually raise the temperature to 170℃, vacuum, add triethanolamine to neutralize, and obtain lignin-modified phenolic resin with a softening point of 115.6℃ and a resin weight-average molecular weight of 4983.

[0125] Example 5

[0126] S1. Add 1.0 mol of styrene-modified phenol, 30 g of rice bran oil, 50 g of toluene, and 1.0 g of dodecylbenzenesulfonic acid to a reaction flask equipped with a stirrer, thermometer, and reflux condenser. Gradually raise the temperature to 90°C, add 0.75 mol of liquid formaldehyde dropwise, and react for 3 hours. Then switch to distillation mode, raise the temperature to 130°C, and after dehydration and solvent removal, obtain a first-stage resin with a low softening point of 63.9°C.

[0127] S2. Change to reflux state, add 50g of lignin, maintain reaction temperature at 150℃, add 5.0g of solid formaldehyde, react for 1.5h, then change to distillation state, gradually raise the temperature to 160℃, vacuum, add triethanolamine to neutralize, and obtain lignin and rice bran oil modified phenolic resin with a softening point of 93.7℃ and a resin weight average molecular weight of 2957.

[0128] Example 6

[0129] S1. Add 1.0 mol of phenol, 0.1 mol of cashew phenol, and 1.0 g of p-toluenesulfonic acid to a reaction flask equipped with a stirrer, thermometer, and reflux condenser. Gradually raise the temperature to 95°C, add 0.85 mol of liquid formaldehyde dropwise, and react for 2 hours. Then, switch to distillation mode, raise the temperature to 140°C, and dehydrate to obtain a first-stage resin with a low softening point of 89.3°C.

[0130] S2. Change to reflux state, add 55g of lignin, maintain reaction temperature at 150℃, add 6.0g of solid formaldehyde, react for 1h, then change to distillation state, gradually raise the temperature to 170℃, vacuum, add triethylamine to neutralize, and obtain lignin and cashew phenol modified phenolic resin with a softening point of 123.6℃ and a resin weight average molecular weight of 5591.

[0131] Example 7

[0132] S1. Add 0.5 mol of styrene-modified phenol, 0.5 mol of phenol, 30 g of water, and 1.0 g of dodecylbenzenesulfonic acid to a reaction flask equipped with a stirrer, thermometer, and reflux condenser. Gradually raise the temperature to 98 °C, add 0.70 mol of liquid formaldehyde dropwise, and react for 2 h. Then switch to distillation mode, raise the temperature to 140 °C, and dehydrate to obtain a first-stage resin with a low softening point of 84.3 °C.

[0133] S2. Change to reflux state, add 50g of lignin and 50g of cashew oil, maintain the reaction temperature at 140℃, add 8.0g of solid formaldehyde, react for 1h, then change to distillation state, gradually raise the temperature to 160℃, vacuum, add triethanolamine to neutralize, and obtain lignin and cashew oil modified phenolic resin with a softening point of 106.0℃ and a resin weight average molecular weight of 4283.

[0134] Comparative Example 1

[0135] 1.0 mol of phenol and 1.0 g of p-toluenesulfonic acid were added to a reaction flask equipped with a stirrer, thermometer and reflux condenser. The temperature was gradually raised to 95°C, and 0.77 mol of 37% liquid formaldehyde was added dropwise. After reacting for 2 hours, the reaction was changed to distillation and the temperature was raised to 150°C. After dehydration and neutralization, phenolic resin was obtained. The resin softening point was 102.4°C and the weight average molecular weight was 3283.

[0136] Comparative Example 2

[0137] 1.0 mol of phenol, 0.1 mol of cashew phenol, and 1.0 g of p-toluenesulfonic acid were added to a reaction flask equipped with a stirrer, thermometer, and reflux condenser. The temperature was gradually raised to 95°C, and 0.86 mol of liquid formaldehyde was added dropwise. After reacting for 2 hours, the mixture was distilled and heated to 150°C. After dehydration and neutralization, cashew phenol-modified formaldehyde resin was obtained. The resin had a softening point of 97.4°C and a weight-average molecular weight of 3688.

[0138] Comparative Example 3

[0139] The difference between it and Example 1 is that:

[0140] Lignin, cashew phenol, and other raw materials are directly mixed, and only a single-stage phenolic condensation reaction occurs. The specific preparation process is as follows:

[0141] 1.0 mol of phenol, 0.1 mol of cashew phenol, 40 g of lignin, and 1.0 g of p-toluenesulfonic acid were added to a reaction flask equipped with a stirrer, thermometer, and reflux condenser. The temperature was gradually raised to 98 °C, and 1.15 mol of 37% liquid formaldehyde was added dropwise. After reacting for 3 hours, the mixture was distilled and heated to 165 °C. After dehydration, the mixture was neutralized with triethanolamine to obtain cashew phenol-modified formaldehyde resin. The resin had a softening point of 95.8 °C and a weight-average molecular weight of 3568.

[0142] In Comparative Example 3, during the reflux reaction at 98℃, it was observed that the lignin agglomerated upon contact with moisture, resulting in incomplete reaction with formaldehyde. After switching to distillation, the dehydration and free phenol processes were also not smooth due to the presence of numerous hydrophilic hydroxyl and methoxy groups in its molecular structure. The distillation time was prolonged, leading to a higher free phenol content in the final resin, significantly higher than that of the modified phenolic resin prepared by the two-stage method provided in the examples. Simultaneously, the formaldehyde utilization efficiency decreased, resulting in some waste.

[0143] Comparative Example 4

[0144] The difference between it and Example 1 is that:

[0145] The lignin is added in a first-stage condensation reaction, and then cashew phenol is added in a second-stage condensation reaction. The specific preparation process includes:

[0146] S1. Add 1.0 mol of phenol, 40 g of lignin, 50 g of toluene, and 1.0 g of p-toluenesulfonic acid to a reaction flask equipped with a stirrer, thermometer, and reflux condenser. Gradually raise the temperature to 95°C, add 0.8 mol of liquid formaldehyde dropwise, and react for 2 hours. Then, switch to distillation mode and raise the temperature to 140°C. After dehydration and solvent removal, a first-stage resin with a low softening point of 75.3°C is obtained.

[0147] S2. Change to reflux state, add 35g of cashew phenol, maintain reaction temperature at 150℃, add 4.5g of second-stage solid formaldehyde, react for 1h, then change to distillation state, gradually raise the temperature to 165℃, vacuum, add triethanolamine to neutralize, and obtain lignin and cashew phenol modified phenolic resin with a softening point of 94.6℃ and a resin weight average molecular weight of 3694.

[0148] Comparative Example 4 uses a two-stage resin preparation method, but adding lignin in the first stage also affects the formaldehyde reaction efficiency and the content of free phenol in the resin.

[0149] In the embodiments of this application, the softening point of the above-mentioned examples and comparative examples was tested according to ASTM D3461-14, unless otherwise stated; the molecular weight of phenolic resin was tested using a gel permeation chromatography system (Waters 1515 separation unit, Waters 2414 differential detector) according to GB / T 27843-2011 (Determination of Low Molecular Weight Components of Chemical Polymers by Gel Permeation Chromatography), wherein tetrahydrofuran was used as the elution solvent, the flow rate was 1.0 mL / min, the sample injection volume was 30 μL, and the sample run time was 35 minutes.

[0150] II. Performance Testing

[0151] (1) Phenolic resins from different embodiments and comparative examples were applied to rubber compositions to prepare vulcanized rubber.

[0152] The raw material formula of the rubber compound is shown in Table 2 below, and the amount of each component is expressed in parts by weight.

[0153] Table 2. Raw material formulation of rubber composition

[0154]

[0155]

[0156] Methods for preparing vulcanized rubber include:

[0157] According to the formulation, standard rubber, carbon black, and zinc oxide are added to a 1.6-liter Banbury internal mixer (manufactured by FARREL) and heated to 155°C. Then, phenolic resin, antioxidant, and cobalt salt are mixed into the rubber component in the internal mixer at a temperature of about 140°C. The masterbatch is cooled to about 90°C. Then, accelerator, sulfur, and methylene donor RA65HMMM (65% loaded with silica) are mixed into the masterbatch, and the above mixture is kneaded at 50°C for 5 minutes to obtain a rubber composition.

[0158] The rubber composition obtained by the above method is molded on a BH-25T flat vulcanizing machine (produced by Bohai Test Machinery Factory, Zhenwu Town, Jiangdu District) to produce vulcanized rubber flat sheets or thin sheets (i.e. reinforcing adhesive materials).

[0159] The mechanical properties, vulcanization properties, and adhesive properties of the prepared rubber composition and / or vulcanized rubber were tested.

[0160] 1) Test methods for mechanical properties

[0161] According to standard GB / T 528-2009, the tensile strength, breaking strength, and elongation at break of the tested materials are measured.

[0162] in:

[0163] Tensile strength, including the tensile stress when the elongation of the specimen reaches 10%, 30%, 50%, 100%, and 300%, respectively, in MPa.

[0164] Tensile strength refers to the tensile stress recorded when a specimen is stretched to the point of fracture, and is measured in MPa.

[0165] Elongation at break refers to the elongation of a specimen at the point of fracture, expressed in units of 100%.

[0166] The Shore hardness of the material is evaluated according to the standard GB / T 531.1-2008.

[0167] 2) Test methods for vulcanization performance

[0168] The vulcanization characteristics of rubber compositions were tested according to standard GB / T 16584-1996, and ML, MH, T90, TS1, TS2, and TS5 were examined.

[0169] in:

[0170] ML refers to the minimum torque, measured in N·m, which characterizes the shear modulus of a rubber composition before vulcanization.

[0171] MH refers to the flat, maximum, and highest torque reached within a specified time, measured in N·m. It characterizes the shear modulus of a rubber composition when it reaches its optimal vulcanization state. The larger the MH value, the greater the crosslinking network density of the rubber composition.

[0172] T90 refers to the optimal vulcanization time, measured in minutes. It characterizes the time required for a rubber composition to reach its optimal vulcanization state. A smaller T90 value indicates a faster vulcanization rate. Generally, T90 is considered to be... 90 A difference of 5% is considered not to be significant.

[0173] TS refers to the time from the start of the experiment until the curve rises from the lowest torque by 0.1 N·m (kgf·cm), in minutes.

[0174] TS2 refers to the time from the start of the experiment to when the curve rises from the lowest torque by 0.2 N·m (kgf·cm), in minutes. TS2 characterizes the operational safety of the rubber compound. The shorter the TS2, the more likely the rubber compound is to become stuck, and the more likely the product will be defective due to material shortage during production.

[0175] The scorch properties of the rubber composition were tested according to standard GB / T 1233-2008 (Determination of initial vulcanization characteristics of unvulcanized rubber using a disc shear viscometer). The test temperature was 151℃, and the scorch time Ts5 was tested using a large rotor.

[0176] The Mooney viscosity of the rubber composition was tested according to standard GB / T 1232.1-2000 (Determination of unvulcanized rubber using a disc shear viscometer - Part 1: Determination of Mooney viscosity). A large rotor was used in the experiment, and the test temperature was 100℃.

[0177] in:

[0178] Mooney viscosity ML100℃(1+4), where 1 in (1+4) represents a preheating time of 1 min and 4 in (1+4) represents a rotation time of 4 min; Mooney viscosity is a measure of the torque applied by a rubber composition to a rotor during rotation. The lower the Mooney viscosity, the better the processing performance of the rubber.

[0179] 3) Test methods for adhesive properties

[0180] The bonding strength between vulcanized rubber and steel cord was tested according to standard GB / T 6586-2014.

[0181] Adhesive strength is measured by the force exerted axially on a single steel wire cord from the embedded rubber in a prepared sample, and is expressed in kN / m. The greater the adhesive force, the higher the adhesive strength.

[0182] (2) The free phenol content of the phenolic resins provided in different embodiments and comparative examples was tested.

[0183] Test method for free phenol content:

[0184] Free phenol content: HPLC was performed using Waters 2996 PPA (mobile phase: tetrahydrofuran + water + methanol; flow rate: 1.0 mL / min; temperature: 30℃; column: Waters Sunfire C18, 250 mm × 4.6 mm), and the sample was injected using an autosampler.

[0185] Table 3. List of mobile phase gradient elution programs

[0186]

[0187] III. Test Results

[0188] The test results of mechanical properties are shown in Table 4, the test results of vulcanization properties are shown in Table 5, and the test results of adhesion properties are shown in Table 6.

[0189] Table 4. Test results of mechanical properties

[0190]

[0191] Table 5. Test results of vulcanization performance

[0192]

[0193] Table 6. Test results of adhesive properties

[0194]

[0195] In formulations 1 and 2, the lignin- and cashew phenol-modified phenolic resins provided in Example 1 are used; in formulation 3, the lignin-modified phenolic resins provided in Example 4 are used; in formulation 4, the unmodified phenolic resins provided in Comparative Example 1 are used; and in formulation 5, the cashew phenol-modified phenolic resins provided in Comparative Example 2 are used.

[0196] Based on Tables 4 to 6, a brief analysis is as follows:

[0197] The data in Table 4 show that the vulcanized rubbers corresponding to the five phenolic resins exhibit comparable tensile strength and hardness before and after aging, prior to tensile failure. Furthermore, compared to formulation 4, the other four formulations show significantly better tensile strength and elongation at break, indicating that, based on the specific preparation method described in this application, modification with lignin and / or cashew phenol can maintain or improve the mechanical properties of the rubber.

[0198] The data in Table 5 show that the five phenolic resin rubber compositions exhibit comparable vulcanization properties for ML, MH, T90, Ts5, and ML(1+4). Furthermore, compared to formulation 4, the TS1 and TS2 times for the other four formulations are significantly longer, indicating that, based on the specific preparation method of this application, modification with lignin and / or cashew phenol can maintain or improve the vulcanization properties of the rubber.

[0199] The data in Table 6 show that, compared to the lignin-modified phenolic resins provided in Comparative Examples 1 and 2, when applied to rubber, the lignin-modified phenolic resins provided in Examples 1, 2, and 4 exhibit significantly better wire bonding performance in rubber before and after aging than the lignin-modified phenolic resins. Furthermore, the bonding performance of rubbers in Examples 1 and 2 after aging is even better than that in Example 4. This indicates that, based on the specific preparation method of this application, lignin modification is beneficial for significantly improving bonding performance, and the simultaneous use of lignin and cashew phenol modification will have an even better effect on improving the bonding performance after aging.

[0200] The data in Tables 4-6 show that, between Example 1 and Example 2, only the time of cashew phenol addition was changed, and the parameters such as the mechanical properties, vulcanization properties, and adhesion properties of the resin were quite similar. This indicates that whether cashew phenol is added in one stage or two stages, it can achieve good modification of the resin.

[0201] The test results of free phenol content in phenolic resin are shown in Table 7.

[0202] Table 7. Test results of free phenol content

[0203] Example 1 Free Phenol Content (%) Example 2 0.32 Example 3 0.65 Example 4 0.25 Comparative Example 1 0.32 Comparative Example 2 0.69 Comparative Example 3 2.98 Comparative Example 4 1.87 surface

[0204] It should be noted that since phenol was not used in the raw materials of Examples 3 to 5, no test results for free phenol were provided.

[0205] Based on Table 7, a brief analysis is as follows:

[0206] In Examples 2, 7, and Comparative Example 1, the reactants in the first stage of condensation reaction were only phenol and formaldehyde. After the reflux reaction was completed, the low-boiling-point phenol was easier to extract under distillation conditions, and the free phenol content in the resin was low.

[0207] In Examples 1, 6, and Comparative Example 2, the feed in the first stage of condensation reaction contained cashew phenol, which has a high boiling point and will affect the evaporation of phenol to some extent, thus increasing the content of free phenol.

[0208] In Comparative Examples 3 and 4, the resins containing lignin in the single-stage condensation reaction had higher free phenol content. This is because the numerous hydrophilic hydroxyl and methoxy groups in the lignin molecule interact with water molecules and the hydroxyl groups in phenol through intermolecular forces, preventing evaporation. Therefore, the free phenol content in these resins is significantly higher than that in the two-stage modified phenolic resins. Excessive free phenol content negatively impacts the resin's performance in rubber applications and also violates environmental protection requirements.

[0209] The embodiments described above are some, but not all, of the embodiments of this application. The detailed description of the embodiments of this application is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

Claims

1. A method for preparing a modified phenolic resin, characterized in that, include: A phenolic compound and a primary aldehyde are subjected to a primary condensation reaction under acidic conditions containing an acid catalyst, followed by a primary dehydration treatment to obtain a primary resin. The molar ratio of the primary aldehyde to the phenolic compound is (0.6~0.8):

1. The phenolic compound is selected from one or more of phenol, cashew nut oil, and styrene-modified phenol. The primary aldehyde is formaldehyde. The acid catalyst is selected from one or more of benzenesulfonic acid, p-toluenesulfonic acid, dodecylbenzenesulfonic acid, and oxalic acid. The primary resin, a secondary aldehyde, and lignin are subjected to a secondary condensation reaction at 100℃~150℃, followed by alkali neutralization treatment to obtain a modified phenolic resin. The amount of lignin used accounts for 5%~40% of the mass of the reaction raw materials. The secondary aldehyde is solid formaldehyde.

2. The preparation method according to claim 1, characterized in that, During the two-stage condensation reaction of the first-stage resin, the second-stage aldehyde, and the lignin, a bio-based raw material is also added to carry out the two-stage condensation reaction together. The bio-based raw material is selected from one or more of cashew phenol, cashew oil, and rice bran oil.

3. The preparation method according to claim 1, characterized in that, In the process of the first-stage condensation reaction of the phenolic compound and the first-stage aldehyde, and / or in the process of the second-stage condensation reaction of the first-stage resin, the second-stage aldehyde and the lignin, at least one of cashew phenol and cashew oil is added together.

4. The preparation method according to claim 3, characterized in that, The total amount of cashew phenol and cashew oil used accounts for 5% to 50% of the mass of the reaction raw materials.

5. The preparation method according to any one of claims 1 to 4, characterized in that, The following conditions (b1) to (b3) must be met: (b1) The softening point of the resin is 60℃ to 90℃; (b2) The softening point of the modified phenolic resin is 90℃ to 130℃; (b3) The weight-average molecular weight of the modified phenolic resin is 2500 to 6000.

6. The preparation method according to claim 5, characterized in that, The following conditions (c1) and (c2) must be met: (c1) In the process of the first-stage condensation reaction of the phenolic compound and the first-stage aldehyde, the first-stage condensation reaction is carried out under reflux, the reaction temperature is 70℃~100℃, and the reaction time is 0.5h~3h; (c2) In the process of the second-stage condensation reaction of the first-stage resin, the second-stage aldehyde, and the lignin, the second-stage condensation reaction is carried out under reflux, and the reaction time is 0.5h~3h.

7. The preparation method according to claim 6, characterized in that, The following conditions (d1) and (d2) must be met: (d1) During the first-stage dehydration process, a heating distillation method is used, with a temperature of 100℃~150℃; (d2) After the second-stage condensation reaction of the first-stage resin, the second-stage aldehyde, and the lignin, a second-stage dehydration process is further included; In the second-stage dehydration process, a heating distillation method is used, with a temperature of 150℃~175℃.

8. The preparation method according to claim 1, characterized in that, The reagent used in the alkali neutralization treatment is selected from one or more of diethylamine, triethylamine, diethanolamine, triethanolamine and 1,8-diazabicyclo[5.4.0]undec-7-ene.

9. A modified phenolic resin, characterized in that, It is prepared by any one of the preparation methods described in claims 1 to 8.

10. A rubber composition, characterized in that, Includes the modified phenolic resin as described in claim 9.

11. The rubber composition according to claim 10, characterized in that, The rubber composition comprises standard rubber, reinforcing filler, zinc oxide, antioxidant, methylene donor, sulfur, accelerator, cobalt salt, and the modified phenolic resin; wherein the reinforcing filler is carbon black or a combination of carbon black and silica; the antioxidant is 6ppd antioxidant; and the accelerator is DZ accelerator.

12. The rubber composition according to claim 11, characterized in that, The rubber composition is used in tire components, which include one or more of the following: a rubber ply of the tire, a tread of the tire, a carcass reinforcement of the tire, and a tread rubber compound of the tire.

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