An epoxidized bio-based itaconate ester rubber and a method of making the same

Abstract

This application provides a method for preparing epoxidized bio-based itaconic acid ester rubber, comprising mixing a bio-based itaconic acid ester rubber emulsion, an emulsifier, an oxidant, and a catalyst to react and obtain epoxidized bio-based itaconic acid ester rubber; the pH of the reaction is 5-7. The method described in this application overcomes the contradiction between ester hydrolysis and epoxidation reaction conditions, achieving direct epoxidation modification of the finished rubber without changing the polymerization process. Furthermore, the method provided in this application allows for wide control of epoxy degree, and ester hydrolysis is effectively suppressed.

Description

Technical Field

[0001] This application relates to the field of rubber materials, specifically to an epoxidized bio-based itaconic acid ester rubber and its preparation method. Background Technology

[0002] Bio-based itaconic acid ester rubbers have a wide range of applications, but the unsaturated carbon-carbon bonds in their molecular chains limit their use. Epoxidation modification is an effective means to improve their performance. Existing technologies include copolymerization to introduce epoxy-containing monomers to achieve epoxy functionalization, but this requires molecular design during the polymerization stage and cannot be applied to pre-polymerized rubber products. Furthermore, the introduction of comonomers may affect the material's fundamental properties. While traditional epoxidation methods are relatively mature in non-polar diene rubbers, they generally suffer from frequent side reactions, stringent reaction conditions, high costs, and the need for organic solvents. Bio-based itaconic acid ester rubbers contain a large number of polar ester side groups in their molecular chains, fundamentally different from traditional non-polar diene rubbers, making existing epoxidation technologies difficult to apply directly.

[0003] Therefore, developing an epoxidation method that requires no organic solvents, is simple to operate, environmentally friendly, can be applied to finished bio-based itaconic acid ester rubber, has few side reactions, and exhibits high selectivity and safety has become an urgent technical problem to be solved. Summary of the Invention

[0004] In view of this, the technical problem to be solved by this application is to provide an epoxidized bio-based itaconic acid ester rubber and a method for preparing the same. The method provided by this application can perform efficient and controllable epoxidation modification on the finished bio-based itaconic acid ester rubber without inducing significant ester group degradation.

[0005] This application provides a method for preparing epoxidized bio-based itaconic acid ester rubber, comprising mixing and reacting a bio-based itaconic acid ester rubber emulsion, an emulsifier, an oxidant and a catalyst to obtain epoxidized bio-based itaconic acid ester rubber; The pH of the reaction is 5-7.

[0006] In some specific implementations, the catalyst is one or more of acetic acid, formic acid, citric acid, oxalic acid, benzoic acid, and carbonic acid.

[0007] In some specific implementations, the bio-based itaconic acid ester rubber latex is a copolymer latex of bio-based itaconic acid ester and conjugated diene; The copolymer emulsion contains 10% to 90% bio-based itaconic acid ester segments and 10% to 90% conjugated diene segments. The solid content of the bio-based itaconic acid ester rubber latex is 20%~50%.

[0008] In some specific implementations, the conjugated diene is selected from one or more of butadiene, isoprene, and myrcene; The bio-based itaconic acid ester is selected from one or more of the following: bio-based dimethyl itaconic acid, bio-based diethyl itaconic acid, bio-based dipropyl itaconic acid, bio-based dibutyl itaconic acid, bio-based dipentyl itaconic acid, bio-based dihexyl itaconic acid, bio-based diheptyl itaconic acid, and bio-based dioctyl itaconic acid.

[0009] In some specific implementations, the emulsifier is selected from one or more of the following: fatty alcohol polyoxyethylene ether AEO-9, fatty alcohol polyoxyethylene ether AEO-15, dodecylphenol polyoxyethylene ether OP-10, octylphenol polyoxyethylene ether OP-15, alkyl glycoside APG0814, alkyl glycoside APG1214, polysorbate Tween 40, polysorbate Tween 60, and polysorbate Tween 80.

[0010] In some specific implementations, the oxidant is hydrogen peroxide.

[0011] In some specific implementations, the mass ratio of the oxidant to the bio-based itaconic acid ester rubber latex is 1:5~110; The mass ratio of the emulsifier to the bio-based itaconic acid ester rubber latex is 1:30~1000.

[0012] In some specific implementations, the reaction temperature is 10℃~30℃.

[0013] This application also provides an epoxidized bio-based itaconic acid ester rubber prepared by the above method.

[0014] In some specific implementations, the epoxy degree of the epoxidized bio-based itaconic acid ester rubber is 0.1% to 9.5%.

[0015] This application provides a method for preparing epoxidized bio-based itaconic acid ester rubber, comprising mixing and reacting a bio-based itaconic acid ester rubber emulsion, an emulsifier, an oxidant, and a catalyst to obtain epoxidized bio-based itaconic acid ester rubber; the pH of the reaction is 5-7. This application provides an epoxidation method specifically for bio-based itaconic acid ester rubber, overcoming the contradiction between ester hydrolysis and epoxidation reaction conditions, and achieving direct epoxidation modification of the finished rubber without changing the polymerization process. Furthermore, the method provided in this application allows for wide control of epoxy degree, and ester hydrolysis is effectively suppressed.

[0016] The epoxidized bio-based itaconic acid ester rubber provided in this application can significantly increase the crosslinking density of the polymer, thereby improving the mechanical strength of the material. The introduction of polar groups improves the material's oil resistance, heat resistance, chemical resistance, and aging resistance. Furthermore, the epoxidized bio-based itaconic acid ester rubber significantly improves the dispersion of silica through the dual effects of chemical bonding and physical adsorption with silica via epoxy groups, which can significantly reduce the amount of silane coupling agent used, thereby reducing VOCs and costs. At the same time, it reduces the rolling resistance of the rubber compound, improves wet skid resistance, reduces heat generation, and enhances adhesion performance, making it suitable for rubber composites for green tires. Attached Figure Description

[0017] Figure 1 This is a comparison of the 1H NMR spectra of the bio-based itaconic acid ester rubber before and after epoxidation in Example 7 of this application. Detailed Implementation

[0018] This application provides an epoxidized bio-based itaconic acid ester rubber and a method for preparing the same. Those skilled in the art can refer to the content of this document and appropriately modify the process parameters to achieve the desired result. The methods and applications of this application have been described through preferred embodiments. Those skilled in the art can clearly modify or appropriately change and combine the methods and applications described herein without departing from the content, spirit, and scope of this application to realize and apply the technology of this application.

[0019] It should be understood that the expression “one or more of…” individually includes each of the objects described after the expression, as well as various different combinations of two or more of the described objects, unless otherwise understood from the context and usage. The expression “and / or” combined with three or more described objects should be understood to have the same meaning, unless otherwise understood from the context.

[0020] The terms “including,” “having,” or “containing,” including the use of their grammatical synonyms, should generally be understood as open-ended and non-restrictive, for example, not excluding other unstated elements or steps, unless otherwise specifically stated or understood from the context.

[0021] It should be understood that the order of steps or the sequence of actions is not important as long as this application remains operational. Furthermore, two or more steps or actions may be performed simultaneously.

[0022] The use of any and all instances or exemplary language such as “e.g.” or “including” herein is merely intended to better illustrate the application and does not constitute a limitation on the scope of the application unless the claims are made. No language in this specification should be construed as indicating that any unclaimed element is essential to the practice of this application.

[0023] Furthermore, the numerical ranges and parameters used to define this application are approximate values, and the relevant values ​​in the specific embodiments have been presented as precisely as possible. However, any numerical value inevitably contains standard deviations due to individual test methods. Therefore, unless otherwise explicitly stated, it should be understood that all ranges, quantities, values, and percentages used in this disclosure are modified with the word "approximately." Here, "approximately" generally means that the actual value is within plus or minus 10%, 5%, 1%, or 0.5% of a specific value or range.

[0024] It should be noted that the bio-based itaconic acid ester rubber described in this application differs fundamentally from traditional non-polar diene rubbers. Traditional non-polar diene rubbers have an all-carbon backbone structure with no polar side groups on the molecular chain. In contrast, the bio-based itaconic acid ester rubber described in this application is copolymerized from itaconic acid dialkyl esters and dienes, and its molecular chain contains a large number of polar ester side groups (-COOR). This structural difference presents a key technical challenge: the ester groups are prone to hydrolysis under both acidic and alkaline conditions. Once hydrolyzed, the polar side chains break, the macromolecular side groups detach, the intermolecular forces decrease significantly, and the crosslinking network gradually disintegrates, resulting in a significant reduction in the adhesion between the rubber and fillers or metal substrates. Furthermore, the carboxylic acid produced by hydrolysis interferes with the sulfur vulcanization system, inhibits the activity of accelerators, and causes insufficient vulcanization and a decrease in mechanical strength. Therefore, in the epoxidation modification process, effectively inhibiting ester hydrolysis and maintaining the integrity of the rubber molecular structure becomes the core challenge that distinguishes it from traditional diene rubber epoxidation technology.

[0025] This application provides a method for preparing epoxidized bio-based itaconic acid ester rubber, comprising mixing and reacting a bio-based itaconic acid ester rubber emulsion, an emulsifier, an oxidant and a catalyst to obtain epoxidized bio-based itaconic acid ester rubber; wherein, the pH of the reaction is preferably 5-7 (more preferably 6-7).

[0026] Specifically, the preparation method of the epoxidized bio-based itaconic acid ester rubber described in this application includes the following steps: A) The bio-based itaconic acid ester rubber latex and the emulsifier are mixed at 10°C to 30°C (preferably 15°C to 25°C) to obtain a mixed latex; B) Add a catalyst to the mixed emulsion, adjust the pH of the system to 5-7 (preferably 6-7), and then slowly add an oxidant to carry out an epoxidation reaction to obtain epoxidized bio-based itaconic acid ester rubber.

[0027] The bio-based itaconic acid ester rubber latex provided in this application is a copolymer latex of bio-based itaconic acid ester and conjugated diene.

[0028] In the copolymer emulsion, the copolymer comprises bio-based itaconic acid ester segments and conjugated diene segments. Preferably, the bio-based itaconic acid ester segments constitute 10% to 90% of the copolymer mass, more preferably 14% to 87%; the conjugated diene segments preferably constitute 10% to 90% of the copolymer mass, more preferably 14% to 87%; the weight-average molecular weight of the copolymer is preferably 100,000 to 1,000,000, more preferably 200,000 to 900,000; the solid content of the bio-based itaconic acid ester rubber emulsion is preferably 20% to 50%, more preferably 20% to 35%.

[0029] In some specific implementations, the conjugated diene is preferably one or more of butadiene, isoprene, and myrcene; the bio-based itaconic acid ester is preferably one or more of bio-based dimethyl itaconic acid, bio-based diethyl itaconic acid, bio-based dipropyl itaconic acid, bio-based dibutyl itaconic acid, bio-based dipentyl itaconic acid, bio-based dihexyl itaconic acid, bio-based diheptyl itaconic acid, and bio-based dioctyl itaconic acid.

[0030] The emulsifier provided in this application is preferably one or more of fatty alcohol polyoxyethylene ether AEO-9, fatty alcohol polyoxyethylene ether AEO-15, dodecylphenol polyoxyethylene ether OP-10, octylphenol polyoxyethylene ether OP-15, alkyl glycoside APG0814, alkyl glycoside APG1214, polysorbate Tween 40, polysorbate Tween 60 and polysorbate Tween 80, more preferably one or more of fatty alcohol polyoxyethylene ether AEO-9, dodecylphenol polyoxyethylene ether OP-10 and alkyl glycoside APG0814.

[0031] In some specific implementations, the mass ratio of the emulsifier to the bio-based itaconic acid ester rubber latex is preferably 1:30~1000, more preferably 1:40~500, and even more preferably 1:40~200.

[0032] The catalyst provided in this application is preferably a weak protic acid, and the weak protic acid is preferably one or more selected from acetic acid, formic acid, citric acid, oxalic acid, benzoic acid, and carbonic acid. This application does not impose any special limitation on the amount of catalyst used, and the amount of catalyst can be adjusted in real time according to the target pH value in the actual system. In this application, the amount of catalyst used is preferably adjusted to a system pH of 5-7 (preferably 6-7).

[0033] The catalyst described in this application can effectively reduce the hydrolysis of itaconic acid ester groups, thereby improving the selectivity and efficiency of the reaction. Compared with traditional methods using strong acid catalysts, this application significantly reduces the hydrolysis rate of itaconic acid ester groups, reduces the occurrence of side reactions, and improves the formation efficiency of the target product.

[0034] The preferred oxidant used in this application is hydrogen peroxide. The preferred use of hydrogen peroxide as the oxidant is environmentally friendly and safe, eliminating the need for organic solvents, simplifying the process, reducing production costs, and avoiding environmental pollution. The stoichiometric ratio of the oxidant described in this application can be calculated based on the molar ratio of the reactants, and the excess coefficient can be adjusted according to the actual reaction conversion rate and selectivity.

[0035] In some specific implementations, the mass ratio of the oxidant to the bio-based itaconic acid ester rubber latex is preferably 1:5 to 110, more preferably 1:10 to 105, and even more preferably 1:15 to 105.

[0036] This application does not impose any particular restrictions on the mixing method used in the mixing process of the various substances, as long as the components are mixed evenly. One or more methods such as ultrasonication, mechanical stirring, magnetic stirring, and homogenization can be used for mixing. The mixing time is preferably 5 min to 60 min, more preferably 5 min to 30 min.

[0037] This application employs real-time monitoring of the reaction temperature during the epoxidation process, checking and recording the data at regular intervals to ensure a constant temperature. The preferred reaction temperature is 10℃~30℃, more preferably 15℃~25℃.

[0038] During the epoxidation reaction, the initial reaction time can be set according to the concentration of reactants and the activity of the catalyst, and the reaction progress indicators can be detected at regular intervals. The reaction is stopped when the target product reaches a predetermined content. In some specific implementations, the reaction time is preferably 2h to 6h, more preferably 2.5h to 5h.

[0039] In some specific implementations, this application monitors the reaction temperature, pH value, and progress indicators (structural characteristics of reaction intermediates) in real time during the epoxidation reaction, and adjusts the reaction parameters in a timely manner to obtain epoxidized bio-based itaconic acid ester rubber with uniform epoxidation degree and controllable epoxy degree.

[0040] In some specific implementations, this application involves post-processing the reaction products to obtain the target product. The post-processing includes processes such as coagulation of the reaction mixture, washing of the coagulated material, and drying to obtain a pure target product.

[0041] The preparation method described in this application involves epoxidation of itaconic acid ester rubber latex without the need for organic solvents as sols. Furthermore, the aqueous system is compatible with protic acids and hydrogen peroxide, making it particularly suitable for the epoxidation preparation of bio-based itaconic acid ester rubber, effectively balancing reaction efficiency and bio-based content. This method overcomes the problems of traditional epoxidation processes, such as the need for organic solvents, frequent side reactions, stringent reaction conditions, and difficulty in controlling the degree of epoxidation. This application optimizes reaction conditions by precisely controlling the reaction temperature and pH, balancing reaction efficiency and selectivity. Simultaneously, it employs stoichiometry and excess coefficient methods to precisely control the amount of hydrogen peroxide, achieving precise control of the degree of epoxidation, thereby improving product performance and application range.

[0042] This application also provides an epoxidized bio-based itaconic acid ester rubber prepared by the above method. The epoxy degree of the epoxidized bio-based itaconic acid ester rubber is 0.1%~9.5%. After double bond epoxidation, the bio-based itaconic acid ester rubber can significantly improve the crosslinking density of the polymer, enhance the mechanical strength of the material, and improve the oil resistance, chemical resistance, heat resistance and aging resistance of the material by introducing polar groups.

[0043] During rubber processing, epoxy groups can solve the dispersion and bonding problems of silica through both chemical and physical effects: during rubber compounding, the epoxy three-membered ring is attacked and opened by the Si-OH bonds of silica, generating Si-OC covalent bonds, which firmly bind the rubber macromolecular chains with silica; unreacted epoxy groups form hydrogen bonds with Si-OH, further enhancing the interfacial stability between organic macromolecules and inorganic fillers. Therefore, the epoxidized bio-based itaconic acid ester rubber can reduce or even eliminate the use of silane coupling agents during preparation, lowering VOCs and costs, while improving the dynamic mechanical properties of the rubber compound (such as reducing rolling resistance, improving wet skid resistance, and reducing heat generation), enhancing the adhesion between the rubber compound and steel wire / fiber skeleton materials, and weakening the Payne effect.

[0044] The present application is further illustrated below with reference to embodiments. The scope of protection of the present application is not limited to the following embodiments.

[0045] Example 1

[0046] 100g of bio-based itaconic acid ester rubber latex (conjugated diene segment content 23%, solid content 25%) was placed in a 250mL four-necked flask. Stirring was started and the water bath temperature was controlled at 15℃. 0.5g of emulsifier OP-10 was added to the latex, followed by the addition of formic acid until the system pH reached 6.1. After stirring for 30min, the system pH was measured to be 6.2. 2.4g of hydrogen peroxide was added, and stirring continued for 5h to terminate the reaction, yielding an epoxidized bio-based itaconic acid ester rubber latex. An appropriate amount of the reacted latex was taken, and anhydrous ethanol was added to precipitate the epoxidized bio-based itaconic acid ester rubber. After drying, 25.16g of epoxidized bio-based itaconic acid ester rubber was obtained. The product was analyzed by 1H NMR spectroscopy, revealing an epoxy degree of 9.5%.

[0047] Example 2

[0048] 100g of bio-based itaconic acid ester rubber latex (87% conjugated diene segment, 35% solids content) was placed in a 250mL four-necked flask. Stirring was started and the water bath temperature was controlled at 20℃. 0.88g of emulsifier AEO-9 was added to the latex, followed by the addition of oxalic acid until the system pH reached 6.8. After stirring for 30min, the pH was tested and found to be 6.8. 1.3g of hydrogen peroxide was added dropwise, and stirring continued for 4h to terminate the reaction, yielding an epoxidized bio-based itaconic acid ester rubber latex. An appropriate amount of the reacted latex was taken, and anhydrous ethanol was added to precipitate the epoxidized bio-based itaconic acid ester rubber. After drying, 35.08g of epoxidized bio-based itaconic acid ester rubber was obtained. The product was analyzed by 1H NMR spectroscopy, revealing an epoxy degree of 0.9%.

[0049] Example 3

[0050] 100g of bio-based itaconic acid ester rubber latex (46% conjugated diene segment, 20% solid content) was placed in a 250mL four-necked flask. Stirring was started and the water bath temperature was controlled at 18℃. 0.25g of emulsifier OP-10 and 0.4g of emulsifier AEO-9 were added to the latex. Acetic acid was then added dropwise until the system pH reached 6.5. After stirring for 30min, the system pH was measured to be 6.7. 2.9g of hydrogen peroxide was added dropwise, and stirring continued for 4.5h to terminate the reaction, yielding an epoxidized bio-based itaconic acid ester rubber latex. An appropriate amount of the reacted latex was taken, and anhydrous ethanol was added to precipitate the epoxidized bio-based itaconic acid ester rubber. After drying, 20.19g of epoxidized bio-based itaconic acid ester rubber was obtained. The product was analyzed by 1H NMR spectroscopy, revealing an epoxy degree of 7.3%.

[0051] Example 4

[0052] 100g of bio-based itaconic acid ester rubber latex (62% conjugated diene segment, 50% solids content) was placed in a 250mL four-necked flask. Stirring was started and the water bath temperature was controlled at 22℃. 2.5g of emulsifier OP-10 was added to the latex, followed by the addition of carbonic acid until the system pH reached 6.9. After stirring for 30min, the pH was measured to be 6.8. 3.3g of hydrogen peroxide was added dropwise, and stirring continued for 3h to terminate the reaction, yielding an epoxidized bio-based itaconic acid ester rubber latex. An appropriate amount of the reacted latex was taken, and anhydrous ethanol was added to precipitate the epoxidized bio-based itaconic acid ester rubber. After drying, 50.20g of epoxidized bio-based itaconic acid ester rubber was obtained. The product was analyzed by 1H NMR spectroscopy, revealing an epoxy degree of 2.2%.

[0053] Example 5

[0054] 100g of bio-based itaconic acid ester rubber latex (conjugated diene segment content 14%, solid content 30%) was placed in a 250mL four-necked flask. Stirring was started and the water bath temperature was controlled at 20℃. 1.2g of emulsifier APG0814 was added to the latex, followed by benzoic acid until the system pH reached 6.7. After stirring for 30min, the system pH was measured to be 6.8. 0.97g of hydrogen peroxide was added dropwise, and stirring continued for 4h to terminate the reaction, yielding an epoxidized bio-based itaconic acid ester rubber latex. An appropriate amount of the reacted latex was taken, and anhydrous ethanol was added to precipitate the epoxidized bio-based itaconic acid ester rubber. After drying, 30.06g of epoxidized bio-based itaconic acid ester rubber was obtained. The product was analyzed by 1H NMR spectroscopy, revealing an epoxy degree of 5.1%.

[0055] Example 6

[0056] 100g of bio-based itaconic acid ester rubber latex (conjugated diene segments accounting for 39%, solid content 25%) was placed in a 250mL four-necked flask. Stirring was started and the water bath temperature was controlled at 25℃. 1.2g of emulsifier AEO-9 was added to the latex, followed by formic acid until the system pH reached 6. After stirring for 30min, the system pH was measured to be 6.2. 3.7g of hydrogen peroxide was added dropwise, and stirring continued for 2.5h to terminate the reaction, yielding an epoxidized bio-based itaconic acid ester rubber latex. An appropriate amount of the reacted latex was taken, and anhydrous ethanol was added to precipitate the epoxidized bio-based itaconic acid ester rubber. After drying, 25.24g of epoxidized bio-based itaconic acid ester rubber was obtained. The product was analyzed by 1H NMR spectroscopy, revealing an epoxy degree of 8.6%.

[0057] Example 7

[0058] 100g of bio-based itaconic acid ester rubber latex (conjugated diene segments accounting for 56%, solid content 25%) was placed in a 250mL four-necked flask. Stirring was started and the water bath temperature was controlled at 16℃. 0.6g of emulsifier APG0814 and 0.8g of emulsifier AEO-9 were added to the latex. Acetic acid was then added dropwise until the system pH reached 7. After stirring and mixing for 30min, the system pH was tested and found to be 7. 3.5g of hydrogen peroxide was added dropwise, and stirring continued for 5h to terminate the reaction, yielding an epoxidized bio-based itaconic acid ester rubber latex. An appropriate amount of the reacted latex was taken, and anhydrous ethanol was added to precipitate the epoxidized bio-based itaconic acid ester rubber. After drying, 25.21g of epoxidized bio-based itaconic acid ester rubber was obtained. The product was analyzed by 1H NMR spectroscopy, and the epoxy degree of the product was found to be 5.3%.

[0059] Example 8

[0060] 100g of bio-based itaconic acid ester rubber latex (72% conjugated diene segment, 40% solid content) was placed in a 250mL four-necked flask. Stirring was started and the water bath temperature was controlled at 23℃. 0.8g of emulsifier APG0814 and 0.4g of emulsifier AEO-9 were added to the latex. Citric acid was then added until the system pH reached 6.5. After stirring for 30 minutes, the system pH was measured to be 6.6. 4.9g of hydrogen peroxide was added dropwise, and stirring continued for 3 hours to terminate the reaction, yielding an epoxidized bio-based itaconic acid ester rubber latex. An appropriate amount of the reacted latex was taken, and anhydrous ethanol was added to precipitate the epoxidized bio-based itaconic acid ester rubber. After drying, 40.26g of epoxidized bio-based itaconic acid ester rubber was obtained. The product was analyzed by 1H NMR spectroscopy, revealing an epoxy degree of 3.1%.

[0061] Example 9

[0062] 100g of bio-based itaconic acid ester rubber latex (conjugated diene segment content 31%, solid content 30%) was placed in a 250mL four-necked flask. Stirring was started and the water bath temperature was controlled at 20℃. 0.9g of emulsifier OP-10 was added to the latex, followed by the addition of acetic acid until the system pH reached 6.5. After stirring for 30min, the system pH was measured to be 6.6. 3.7g of hydrogen peroxide was added, and stirring continued for 4h to terminate the reaction, yielding an epoxidized bio-based itaconic acid ester rubber latex. An appropriate amount of the reacted latex was taken, and anhydrous ethanol was added to precipitate the epoxidized bio-based itaconic acid ester rubber. After drying, 30.21g of epoxidized bio-based itaconic acid ester rubber was obtained. The product was analyzed by 1H NMR spectroscopy, revealing an epoxy degree of 7.9%.

[0063] Comparative Example 1

[0064] Compared to Example 1, only the pH of the reaction system was changed: 100g of bio-based itaconic acid ester rubber latex (conjugated diene segment ratio of 23%, solid content of 25%) was placed in a 250mL four-necked flask. Stirring was started and the water bath temperature was controlled at 15℃. 0.5g of emulsifier OP-10 was added to the latex, and then formic acid was added dropwise until the system pH reached 9. After stirring and mixing for 30min, the system pH was tested and found to be 9.1. 2.4g of hydrogen peroxide was added dropwise, and the reaction was stopped after stirring for another 5h, yielding an epoxidized bio-based itaconic acid ester rubber latex. An appropriate amount of the reacted latex was taken, and anhydrous ethanol was added to precipitate the epoxidized bio-based itaconic acid ester rubber. After drying, 25.00g of epoxidized bio-based itaconic acid ester rubber was obtained. The product was analyzed by 1H NMR spectroscopy, and the epoxy degree of the product was found to be 0%.

[0065] The results showed that, compared with Example 1, the epoxy degree of the product of Comparative Example 1 was 0%, indicating that the epoxidation reaction was completely inhibited under alkaline conditions and failed to occur.

[0066] Comparative Example 2

[0067] Compared with Example 1, only the pH of the reaction system was changed: 100g of bio-based itaconic acid ester rubber latex (conjugated diene segment ratio of 23%, solid content of 25%) was placed in a 250mL four-necked flask. Stirring was started and the water bath temperature was controlled at 15℃. 0.5g of emulsifier OP-10 was added to the latex, and then formic acid was added dropwise until the system pH reached 4. After stirring and mixing for 30min, the system pH was tested and found to be 4.7. 2.4g of hydrogen peroxide was added dropwise, and the reaction was stopped after stirring for another 5h, yielding an epoxidized bio-based itaconic acid ester rubber latex. An appropriate amount of the reacted latex was taken, and anhydrous ethanol was added to precipitate the epoxidized bio-based itaconic acid ester rubber. After drying, 25.04g of epoxidized bio-based itaconic acid ester rubber was obtained. The product was analyzed by 1H NMR spectroscopy, and the epoxy degree of the product was found to be 2.7%.

[0068] The results showed that, compared with Example 1, the epoxy degree of the product in Comparative Example 2 was only 2.7%, significantly lower than that in Example 1. This indicates that the pH of the reaction system has a significant impact on the efficiency of the epoxidation reaction; too low a pH is not conducive to the epoxidation reaction, and the epoxy degree of the product is greatly reduced.

[0069] Test Example 1

[0070] Structural characterization of bio-based itaconic acid ester rubber before and after epoxidation

[0071] Bio-based itaconic acid ester rubber samples before and after the epoxidation reaction in Example 7 were subjected to 1H NMR spectroscopy to compare and analyze the changes in their chemical structure. The test results are as follows: Figure 1 As shown, Figure 1This is a comparison of the 1H NMR spectra of the bio-based itaconic acid ester rubber before and after epoxidation in Example 7 of this application. The test results show that the bio-based itaconic acid ester rubber exhibits a new characteristic absorption peak at a chemical shift of 2.68 ppm after the epoxidation reaction. Analysis revealed that the characteristic peak at the chemical shift of 2.68 ppm is attributed to the characteristic absorption peak of the proton attached to the epoxide carbon. The appearance of this characteristic peak indicates that some carbon-carbon double bonds in the bio-based itaconic acid ester rubber molecular chain have been successfully converted into epoxide groups, meaning that the epoxidation reaction has proceeded smoothly.

[0072] The above description is merely a preferred embodiment of this application, but the scope of protection of this application is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in this application, based on the technical solution and inventive concept of this application, should be included within the scope of protection of this application.

Claims

1. A method for preparing epoxidized bio-based itaconic acid ester rubber, characterized in that, The process involves mixing and reacting a bio-based itaconic acid ester rubber emulsion, an emulsifier, an oxidant, and a catalyst to obtain epoxidized bio-based itaconic acid ester rubber. The pH of the reaction is 5-7.

2. The preparation method according to claim 1, characterized in that, The catalyst is one or more of acetic acid, formic acid, citric acid, oxalic acid, benzoic acid, and carbonic acid.

3. The preparation method according to claim 1, characterized in that, The bio-based itaconic acid ester rubber latex is a copolymer latex of bio-based itaconic acid ester and conjugated diene; The copolymer emulsion contains 10% to 90% bio-based itaconic acid ester segments and 10% to 90% conjugated diene segments. The solid content of the bio-based itaconic acid ester rubber latex is 20%~50%.

4. The preparation method according to claim 3, characterized in that, The conjugated diene is selected from one or more of butadiene, isoprene and myrcene; The bio-based itaconic acid ester is selected from one or more of the following: bio-based dimethyl itaconic acid, bio-based diethyl itaconic acid, bio-based dipropyl itaconic acid, bio-based dibutyl itaconic acid, bio-based dipentyl itaconic acid, bio-based dihexyl itaconic acid, bio-based diheptyl itaconic acid, and bio-based dioctyl itaconic acid.

5. The preparation method according to claim 1, characterized in that, The emulsifier is selected from one or more of the following: fatty alcohol polyoxyethylene ether AEO-9, fatty alcohol polyoxyethylene ether AEO-15, dodecylphenol polyoxyethylene ether OP-10, octylphenol polyoxyethylene ether OP-15, alkyl glycoside APG0814, alkyl glycoside APG1214, polysorbate Tween 40, polysorbate Tween 60, and polysorbate Tween 80.

6. The preparation method according to claim 1, characterized in that, The oxidant is hydrogen peroxide.

7. The preparation method according to claim 1, characterized in that, The mass ratio of the oxidant to the bio-based itaconic acid ester rubber latex is 1:5~110; The mass ratio of the emulsifier to the bio-based itaconic acid ester rubber latex is 1:30~1000.

8. The preparation method according to claim 1, characterized in that, The reaction temperature is 10℃~30℃.

9. An epoxidized bio-based itaconic acid ester rubber prepared by the method according to any one of claims 1 to 8.

10. The epoxidized bio-based itaconic acid ester rubber according to claim 9, characterized in that, The epoxy content of the epoxidized bio-based itaconic acid ester rubber is 0.1% to 9.5%.

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