A bio-based functionalized rubber processing aid, and methods of making and using the same

Abstract

This invention discloses a bio-based functionalized rubber processing aid, its preparation method, and its application, belonging to the field of rubber production and processing technology. The preparation method includes: dissolving cashew phenol glycidyl ether (CGE), an aromatic diamine, and an imidazole catalyst in an organic solvent for reaction, followed by purification, column chromatography, and vacuum drying to obtain the processing aid (CGAD). By reacting CGE with the aromatic diamine, a large number of hydroxyl groups and more rigid structures are introduced. When introduced into the styrene-butadiene rubber / fumed silica system, CGAD retains the original long-chain aromatic ring structure of CGE, which can interact with the rubber matrix and also has a certain plasticizing ability. Furthermore, compared to CGE, CGAD has significantly improved molecular polarity and the number of polar groups. Therefore, when it interacts more tightly with the hydroxyl groups on the surface of fumed silica, the filler network is more significantly disrupted, and the dispersibility is better, thereby further enhancing the mechanical properties and wear resistance of the material.

Description

Technical Field

[0001] This invention relates to the field of rubber production and processing technology, specifically to a bio-based functionalized rubber processing aid, its preparation method, and its application. Background Technology

[0002] In the industrial production of rubber, various functional processing aids are often added. These aids are added in small quantities but play a very important role, usually significantly improving a certain property of the rubber and enhancing product quality. These processing aids are mainly petroleum-based, expensive, and pose significant risks to human health and the environment.

[0003] Silica, a commonly used reinforcing filler, is widely used in rubber products due to its excellent reinforcing effect, low thermal expansion, and superior abrasion resistance. However, silica has poor dispersibility in rubber matrices and often tends to agglomerate, which affects the dynamic properties, mechanical properties, and processing properties of the composite material.

[0004] In summary, to address these issues, it is often necessary to add additives to improve the compatibility between silica and the rubber matrix. Current research has shown that cashew phenol glycidyl ether (CGE) can be directly added to the silica-rubber system as a processing aid. However, compared to traditional silane coupling agent modification, this method results in a decrease in the tensile and abrasion resistance of the material. Therefore, it is necessary to improve the process for preparing rubber composites using CGE as a processing aid to further enhance the overall performance of the rubber composites. Summary of the Invention

[0005] This invention provides a bio-based functionalized rubber processing aid, its preparation method, and its application, aiming to solve existing technical problems such as poor dispersion of silica and high processing difficulty of rubber compounds. This invention synthesizes a novel bio-based functionalized rubber processing aid (CGAD) using cashew phenol glycidyl ether (CGE) and an organic aromatic diamine. Compared to directly adding CGE, this novel molecular structure further improves many aspects of rubber composites.

[0006] To achieve the above objectives, in a first aspect, the present invention provides a method for preparing a bio-based functionalized rubber processing aid, comprising the following steps: S1, cashew phenol glycidyl ether, aromatic diamine and imidazole catalyst are dissolved in an organic solvent at a mass ratio of 1:(0.2~0.6):(0.001~0.01), and reacted at 80~120℃ to obtain crude product; S2, the crude product is purified and vacuum dried to obtain a bio-based functionalized rubber processing aid.

[0007] As a further preferred embodiment of the present invention, the aromatic diamine is at least one of 4,4'-dithiodiphenylamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl sulfone, and 4,4'-diaminodiphenyl ether, and more preferably 4,4'-dithiodiphenylamine.

[0008] As a further preferred embodiment of the present invention, the imidazole catalyst is at least one selected from imidazole, 2-methylimidazolium, 1,2-dimethylimidazolium, 2-ethyl-4-methylimidazolium, and 2-phenylimidazolium.

[0009] As a further preferred embodiment of the present invention, the organic solvent is at least one selected from anhydrous ethanol, acetone, toluene, N-methylpyrrolidone, and dimethyl sulfoxide.

[0010] As a further preferred embodiment of the present invention, the reaction is stirred at a speed of 400-500 rpm.

[0011] As a further preferred embodiment of the present invention, the reaction time is 8-12 hours.

[0012] As a further preferred embodiment of the present invention, the amount of cashew phenol glycidyl ether used is 1 to 10 wt% of the amount of organic solvent used.

[0013] As a further preferred embodiment of the present invention, the cashew phenol glycidyl ether is one or a mixture of several of the following four structural compounds, and more preferably includes the following four structural compounds: In the formula, R can have the following structures: .

[0014] According to a second aspect of the present invention, the present invention also provides a bio-based functionalized rubber processing aid, which is obtained by the above-described preparation method.

[0015] According to a second aspect of the invention, the invention also provides the application of a bio-based functionalized rubber processing aid in rubber.

[0016] This invention utilizes the condensation reaction of the highly reactive epoxy group of cashew phenol glycidyl ether with the amino group of an aromatic diamine compound to obtain a compound with multiple active groups and symmetrical long side chains. The preparation method is simple and the reaction is mild. In one example, the reaction mechanism of cashew phenol glycidyl ether with 4,4'-dithiodiphenylamine is as follows: The bio-based functionalized rubber processing aid prepared in this invention can be applied to both natural and synthetic rubber, thereby improving the overall performance of rubber composites. Compared to directly using CGE as a processing aid, this invention introduces a large number of hydroxyl groups and more rigid structures into the molecule of CGE after reacting with aromatic diamines. When introduced into the styrene-butadiene rubber / fumed silica system, on the one hand, CGAD retains the original long-chain aromatic ring structure of CGE, which can interact with the rubber matrix and also has a certain plasticizing ability; on the other hand, compared with CGE, CGAD has significantly improved both molecular polarity and the number of polar groups. Therefore, when it interacts more tightly with the hydroxyl groups on the surface of fumed silica, the filler network is more significantly disrupted, and the dispersibility is better, thus further enhancing the mechanical properties and wear resistance of the material. In addition, the amine groups in the molecular structure can also promote the vulcanization reaction and shorten the vulcanization time, thereby improving the vulcanization efficiency and further improving the overall performance of the rubber composite. Attached Figure Description

[0017] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0018] Figure 1 The infrared spectra of the bio-based functionalized rubber processing aids in Examples 1-4 are shown.

[0019] Figure 2 The thermogravimetric curves of the bio-based functionalized rubber processing aids in Examples 1-4 are shown.

[0020] Figure 3 Vulcanization curves of styrene-butadiene rubber / fumed silica composites with and without added bio-based functionalized rubber processing aids.

[0021] Figure 4 Stress-strain curves of styrene-butadiene rubber / fumed silica composites with and without added bio-based functionalized rubber processing aids.

[0022] The objectives, features, and advantages of this invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0023] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0024] Unless otherwise defined, the technical terms used in the following embodiments have the same meanings as commonly understood by those skilled in the art to which this invention pertains. Unless otherwise specified, the experimental reagents used in the following embodiments are conventional biochemical reagents; and the experimental methods described are conventional methods.

[0025] The cashew phenol glycidyl ether used in the following examples is Macklin C992604, with a purity of 99%.

[0026] Example 1 This embodiment provides a method for preparing a bio-based functionalized rubber processing aid (CGAD), comprising: S1, weigh out 20g of cashew phenol glycidyl ether, 6g of 4,4'-dithiodiphenylamine, 0.1g of 2-ethyl-4-methylimidazole, 0.1g of 2-phenylimidazole, and 200g of acetone. Pour the cashew phenol glycidyl ether into a three-necked flask equipped with a thermometer and a condenser. Add acetone to the flask, then add 2-ethyl-4-methylimidazole sequentially. After mixing thoroughly, add 4,4'-dithiodiphenylamine. React under a nitrogen atmosphere at 80℃ and 450rpm for 12 hours with constant stirring to obtain the crude product.

[0027] S2, the crude product was washed with dimethyl sulfoxide and anhydrous ethanol respectively. After washing and centrifugation three times, the precipitate was collected, the washings were vacuum filtered, and finally dried in a vacuum oven for 24 hours to obtain the pure product.

[0028] Example 2 S1, weigh out 20g of cashew phenol glycidyl ether, 6g of 4,4'-dithiodiphenylamine, 0.1g of 2-ethyl-4-methylimidazole, 0.1g of 2-phenylimidazole, and 200g of acetone. Pour the cashew phenol glycidyl ether into a three-necked flask equipped with a thermometer and a condenser. Add acetone to the flask, then add 2-ethyl-4-methylimidazole sequentially. After mixing thoroughly, add 4,4'-dithiodiphenylamine. React under a nitrogen atmosphere at 100℃ and 450rpm for 10 hours with constant stirring to obtain the crude product.

[0029] S2, the crude product was washed with dimethyl sulfoxide and anhydrous ethanol respectively. After washing and centrifugation three times, the precipitate was collected, the washings were vacuum filtered, and finally dried in a vacuum oven for 24 hours to obtain the pure product.

[0030] Example 3 S1, weigh out 20g of cashew phenol glycidyl ether, 6g of 4,4'-dithiodiphenylamine, 0.1g of 2-ethyl-4-methylimidazole, 0.1g of 2-phenylimidazole, and 200g of acetone. Pour the cashew phenol glycidyl ether into a three-necked flask equipped with a thermometer and a condenser. Add acetone to the flask, then add 2-ethyl-4-methylimidazole sequentially. After mixing thoroughly, add 4,4'-dithiodiphenylamine. React under a nitrogen atmosphere at 120℃ and 450rpm for 8 hours with constant stirring to obtain the crude product.

[0031] S2, the crude product was washed with dimethyl sulfoxide and anhydrous ethanol respectively. After washing and centrifugation three times, the precipitate was collected, the washings were vacuum filtered, and finally dried in a vacuum oven for 24 hours to obtain the pure product.

[0032] Example 4 S1, weigh out 20g of cashew phenol glycidyl ether, 6g of 4,4'-dithiodiphenylamine, 0.1g of 2-ethyl-4-methylimidazole, 0.1g of 2-phenylimidazole, and 200g of acetone. Pour the cashew phenol glycidyl ether into a three-necked flask equipped with a thermometer and a condenser. Add acetone to the flask, followed by 2-ethyl-4-methylimidazole. After mixing thoroughly, add 4,4'-diaminodiphenylmethane. React under a nitrogen atmosphere at 140℃ and 450rpm for 6 hours with constant stirring to obtain the crude product.

[0033] S2, the crude product was washed with dimethyl sulfoxide and anhydrous ethanol respectively. After washing and centrifugation three times, the precipitate was collected, the washings were vacuum filtered, and finally dried in a vacuum oven for 24 hours to obtain the pure product.

[0034] The effects of reaction temperature and reaction time on the products were studied through the above four sets of comparative examples, and infrared and thermogravimetric analyses were performed on them. Infrared spectroscopy tests were performed on Examples 1-4, and the test results are as follows: Figure 1 As shown. From Figure 1 It can be seen that the various embodiments are at 910cm -1 Located at 860 cm -1 The characteristic peaks of the epoxy groups were significantly weakened after the reaction, remaining in the 3200-3600 cm⁻¹ range. - The presence of a broad and strong hydroxyl stretching vibration peak indicates that a corresponding reaction has indeed occurred.

[0035] Thermogravimetric analysis was performed on Examples 1-4, and the test results are as follows: Figure 2 As shown. From Figure 2 It can be seen that the thermogravimetric curves of each embodiment before and after the reaction are significantly different from those of cashew phenol glycidyl ether, and the reactants have a single thermal decomposition temperature, which is relatively close to each other, indicating that the structure of the substances changed before and after the reaction.

[0036] Infrared and thermogravimetric analyses revealed that the products obtained in Examples 1-4 have similar structures. Therefore, only the product of Example 1 (CGAD) was used for further testing in styrene-butadiene rubber / fumed silica composites.

[0037] Application Example 1 The SSBR / silica composite material was prepared according to the formulation in Table 1, as follows: First, silica and Si69 were mixed evenly. Then, styrene-butadiene rubber was placed in a Banbury mixer and plasticized for 1 minute. Next, silica and the synthetic bio-based functionalized rubber processing aid CGAD were added, and the mixture was mixed for a period of time before being discharged. Throughout the process, the Banbury mixer temperature was 150℃, the speed was 50 rpm, and the mixing time was 5 minutes. After discharge, the compound and other additives were further mixed on a two-roll mill. The order of addition was: compound - zinc oxide + hard acid - accelerator - antioxidant - sulfur. The mixture was continuously turned until the added additives were evenly dispersed, and then sheeted. Finally, the compound was left at room temperature for a period of time before relevant tests were conducted.

[0038] Application Comparative Example 1 As a control experiment for Application Example 1, the only difference from Application Example 1 was that the processing aid CGAD was replaced with the same mass of cashew phenol glycidyl ether (CGE), while the rest of the process remained the same.

[0039] Application Comparative Example 2 As a control experiment for Application Example 1, the only difference from Application Example 1 is that the processing aid CGAD is replaced with the same mass of processing aid CGP prepared by reacting cashew phenol glycidyl ether with p-aminodiphenylamine; all other processes remain the same. The preparation method of the processing aid CGP is basically the same as in Example 1, except that the aromatic diamine used is different.

[0040] The compound rubbers prepared in the above application comparative examples 1 and 2 and application example 1 are respectively referred to as: Sample 1, Sample 2 and Sample 3.

[0041] Table 1. Formulation of SSBR / Silica Composite Material (parts by weight) In Table 1: the grade of solution-polymerized styrene-butadiene rubber is 2466; the grade of silica is GR7000; Si69 is bis-[γ-(triethoxysilyl)propyl]tetrasulfide; CZ is N-cyclohexyl-2-benzothiazole sulfenamide; TMTD is tetramethylthiuram disulfide; and 4010NA is N-(1,3-dimethylbutyl).

[0042] The compound rubbers prepared in Comparative Examples 1 and 2 and Application Example 1 were tested for vulcanization performance using a rotorless vulcanizing apparatus. The test results are shown in Table 2. Figure 3 As shown.

[0043] Table 2. Vulcanization parameters of SSBR / silica composite material In Table 2, MH represents the maximum vulcanization torque, ML represents the minimum vulcanization torque, and Tc... 10 The time required for 10% vulcanization, Tc90 The time required for 90% vulcanization.

[0044] From Table 2 and Figure 3 It can be seen that, compared with sample 1 which only added cashew phenol glycidyl ether and sample 2 which added CGP, the Tc of sample 3 is higher. 10 and Tc 90 The vulcanization time was significantly shortened, by approximately 12.2%, 9.0%, 30.9%, and 18.1% respectively, while the maximum vulcanization torque remained relatively similar across the three. This indicates that the introduction of CGAD effectively improves the vulcanization rate of the system and reduces the time required for rubber products during molding and processing. This is because the aromatic amine groups on CGAD can promote the vulcanization of rubber. These groups can participate in the activation reaction of the molecular chains during vulcanization and work synergistically with the accelerator to accelerate the formation of the cross-linked network.

[0045] Furthermore, the tensile properties of the rubber compounds prepared in Comparative Examples 1 and 2 and Application Example 1 were tested using a universal testing machine after vulcanization at 150°C. The test results are shown in Table 3. Figure 4 As shown.

[0046] From Table 3 and Figure 4 It can be seen that compared with samples 1 and 2, sample 3 showed improvements in tensile strength, elongation at break, and tear strength to varying degrees. Specifically, the tensile strength increased by 9.8% and 5.0%, respectively; the elongation at break increased by 14.6% and 10.3%, respectively; and the tear strength increased by 7.1% and 4.0%, respectively. The stresses at 100% and 300% of their relative elongation remained close. This indicates that the introduction of CGAD significantly enhances the reinforcing effect of the filler, improving the flexibility and ductility of the system. This is because CGAD molecules are more rigid and interact more significantly with the filler, resulting in a significant improvement in the mechanical properties of the rubber composite material.

[0047] Table 3 Mechanical properties of SSBR / fumed silica composites Furthermore, the abrasion resistance of the compound prepared by Application Comparative Example 1, Application Comparative Example 2 and Application Example 1 was measured using an Akron abrasion tester. The test results are shown in Table 4, where ΔV is the wear volume.

[0048] Table 4. Abrasion Volume of SSBR / Silica Composite Material in Akra As shown in Table 4, compared with samples 1 and 2, the wear volume of sample 3 was significantly reduced, by 22.7% and 21.8% respectively. This indicates that the introduction of CGAD can effectively improve the wear resistance of the composite material and extend the service life of the product. This is because CGAD molecules have a strong interaction with silica, which can further enhance the bonding between the rubber and the filler.

[0049] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and various changes or modifications can be made to these embodiments without departing from the principles and essence of the present invention. The scope of protection of the present invention is defined only by the appended claims.

Claims

1. A method for preparing a bio-based functionalized rubber processing aid, characterized in that, Includes the following steps: S1, cashew phenol glycidyl ether, aromatic diamine and imidazole catalyst are dissolved in an organic solvent at a mass ratio of 1:(0.2~0.6):(0.001~0.01), and reacted at 80~120℃ to obtain crude product; S2, the crude product is purified and dried to obtain a bio-based functionalized rubber processing aid.

2. The method for preparing the bio-based functionalized rubber processing aid according to claim 1, characterized in that, The aromatic diamine is at least one selected from 4,4'-dithiodiphenylamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl sulfone, and 4,4'-diaminodiphenyl ether.

3. The method for preparing the bio-based functionalized rubber processing aid according to claim 1, characterized in that, The imidazole catalyst is at least one selected from imidazole, 2-methylimidazolium, 1,2-dimethylimidazolium, 2-ethyl-4-methylimidazolium, and 2-phenylimidazolium.

4. The method for preparing the bio-based functionalized rubber processing aid according to claim 1, characterized in that, The organic solvent is at least one of anhydrous ethanol, acetone, toluene, N-methylpyrrolidone, and dimethyl sulfoxide.

5. The method for preparing the bio-based functionalized rubber processing aid according to claim 1, characterized in that, The reaction is stirred at a speed of 400-500 rpm.

6. The method for preparing the bio-based functionalized rubber processing aid according to claim 1, characterized in that, The reaction time is 8-12 hours.

7. The method for preparing the bio-based functionalized rubber processing aid according to claim 1, characterized in that, The amount of cashew phenol glycidyl ether used is 1 to 10 wt% of the amount of organic solvent used.

8. The method for preparing the bio-based functionalized rubber processing aid according to claim 1, characterized in that, The cashew phenol glycidyl ether is at least one of the following four structural compounds: In the formula, R can have the following structures: 。 9. A bio-based functionalized rubber processing aid prepared by the preparation method according to any one of claims 1-8.

10. The application of the bio-based functionalized rubber processing aid according to claim 9 in rubber.

Images