A bio-based low temperature resistant elastomer, a method for preparing the same and a rubber composition

Abstract

The application discloses a kind of bio-based low-temperature-resistant elastomer and its preparation method and rubber composition.The bio-based low-temperature-resistant elastomer of the application contains conjugated diene hydrocarbon structural unit and terpene compound structural unit;With the total mole of conjugated diene hydrocarbon structural unit and terpene compound structural unit 100%, the mole content of terpene compound structural unit is 5-60%, and the mole content of conjugated diene hydrocarbon structural unit is 40-95%;The number average molecular weight of the bio-based low-temperature-resistant elastomer is 200-300 thousand, and molecular weight distribution coefficient PDI=2.0-4.5.The bio-based low-temperature-resistant elastomer of the application has 90-96% cis 1,4 structure, has low glass transition temperature, and does not crystallize at low temperature, and is used in low-temperature-resistant winter tire, in line with the needs of green development, can alleviate the problem of increasingly exhausted fossil resources, and has important significance for sustainable development.

Description

Technical Field

[0001] This invention relates to the field of chemically synthesized rubber technology, specifically to a bio-based low-temperature resistant elastomer, its preparation method, and a rubber composition thereof. Background Technology

[0002] In my country, all-season tires are the most commonly used type of automobile tire. Compared to traditional tires, winter tires require tread materials with better low-temperature resistance to ensure superior grip and anti-skid performance on icy and snowy roads. In terms of tire structure, they need wider and deeper tread patterns to maintain high handling and braking performance on slippery winter surfaces. Currently, commonly used winter tire tread materials mainly include butadiene rubber (lower Tg) and solution-polymerized styrene-butadiene rubber (better anti-skid performance). The monomers for synthesizing butadiene rubber and styrene-butadiene rubber are primarily derived from fossil resources. Developing a novel bio-based low-temperature resistant rubber is of great significance for the sustainable development of the tire industry.

[0003] The low-temperature resistance of rubber mainly depends on its crystallinity and glass transition temperature. As the temperature decreases, rubber crystallizes, or it reaches its glass transition temperature, causing it to harden and lose elasticity. Commonly used natural rubber is primarily polyisoprene with a high cis-1,4 structure. Although it has a relatively low glass transition temperature, it slowly crystallizes at low temperatures. Styrene-butadiene rubber (SBR), due to the presence of benzene rings, does not crystallize at low temperatures, but this also leads to an increased glass transition temperature. To better meet the requirements of rubber materials used in low-temperature environments and reduce the use of fossil resources, developing an environmentally friendly, bio-based, low-temperature resistant elastomer is of great significance.

[0004] Therefore, there is a need for an environmentally friendly, low-temperature resistant rubber material. Summary of the Invention

[0005] To address the problems in existing technologies, this invention provides a bio-based low-temperature resistant elastomer, its preparation method, and a rubber composition. The preparation method of the bio-based low-temperature resistant elastomer includes: coordinating chain transfer polymerization of a bio-based monomeric terpene compound and a conjugated diene to obtain a random copolymer (i.e., the bio-based low-temperature resistant elastomer), wherein the terpene compound structural unit accounts for 5-60 mol.% of the random copolymer. This copolymer has 90-96% cis-1,4 structure, a low glass transition temperature, and does not crystallize at low temperatures, making it suitable for use in winter tires to meet the requirements for use in low-temperature environments. This invention applies coordinating chain transfer polymerization, which can control polymer structure, to bio-based terpene compound monomers, enabling the synthesis of high-molecular-weight bio-based low-temperature resistant elastomers with high cis-1,4 structure content. This is of great significance for sustainable development, and its application in low-temperature resistant winter tires aligns with the needs of green development and can alleviate the problem of increasingly depleted fossil resources.

[0006] One objective of this invention is to provide a bio-based low-temperature resistant elastomer containing conjugated diene structural units and terpene compound structural units;

[0007] The conjugated diene structural unit is shown in formula (I):

[0008] Wherein, R1 is H or CH3, preferably CH3;

[0009] The terpene compound structural unit is at least one of the structural units shown in formula (II), formula (III), and formula (IV);

[0010]

[0011] Based on the total molar amount of conjugated diene structural units and terpene structural units (100%), the molar content of terpene structural units is 5-60%, preferably 5-50%, more preferably 10-40%, and the molar content of conjugated diene structural units is 40-95%, preferably 50-95%, more preferably 60-90%. The number-average molecular weight of the bio-based low-temperature resistant elastomer is 20,000-300,000, preferably 100,000-300,000, and the molecular weight distribution coefficient (PDI) is 2.0-4.5, preferably 2.0-3.0.

[0012] In a preferred embodiment of the present invention,

[0013] The structural units of the bio-based low-temperature resistant elastomer are 90-96% 1,4 cis structure, preferably 91-94% 1,4 cis structure.

[0014] A second objective of this invention is to provide a method for preparing a bio-based low-temperature resistant elastomer, which is one of the objectives of this invention, comprising the step of carrying out a coordination polymerization reaction of a terpene compound and a conjugated diene in a solvent in the presence of a neodymium catalyst system.

[0015] In a preferred embodiment of the present invention,

[0016] The terpene compound is at least one of myrcene, β-farnesene, and ocimene, preferably myrcene; and / or,

[0017] The conjugated diene is at least one of isoprene and butadiene, preferably isoprene; and / or

[0018] The solvent is at least one selected from n-hexane and cyclohexane; and / or,

[0019] The molar amount of the terpene compound is 5% to 60% of the total molar amount of the terpene compound and the conjugated diene, preferably 5% to 50%, more preferably 5% to 30%; and / or,

[0020] The mass ratio of the total mass of the terpene compound and the conjugated diene to the solvent is 1:3 to 10, preferably 1:4 to 10, and more preferably 1:4 to 6.

[0021] In a preferred embodiment of the present invention,

[0022] The neodymium-based catalyst system comprises neodymium carboxylate, alkylaluminum, halogen-containing compounds, and conjugated diene A;

[0023] Preferably,

[0024] The neodymium carboxylate compound is at least one selected from neodymium naphthenate, neodymium octanoate, neodymium decanoate, and neodymium neodecanoate, more preferably neodymium neodecanoate; and / or,

[0025] The alkylaluminum is at least one selected from trimethylaluminum, triethylaluminum, tripropylaluminum, triisobutylaluminum, diethylaluminum hydride, and diisobutylaluminum hydride, more preferably triisobutylaluminum or diisobutylaluminum hydride; and / or,

[0026] The halogen-containing compound is at least one selected from sesquiethylaluminum chloride, diethylaluminum chloride, dimethylchlorosilane, and dimethyldichlorosilane, more preferably at least one selected from sesquiethylaluminum chloride and diethylaluminum chloride; and / or,

[0027] The conjugated diene A is at least one selected from butadiene, isoprene, 1,3-pentadiene, and 1,3-hexadiene, more preferably at least one selected from butadiene and isoprene; and / or

[0028] The molar ratio of the neodymium carboxylate compound, alkylaluminum, halogen-containing compound, and conjugated diene A is 1:(10–30):(1–10):(5–20); and / or,

[0029] The molar ratio of the neodymium carboxylate compound to the total molar amount of the terpene compound and the conjugated diene is 1.5 × 10⁻⁶. -4 ~1.5×10 -3 Preferably 1×10 -3 ~1.5×10 -3 .

[0030] In a preferred embodiment of the present invention,

[0031] The temperature of the coordination polymerization reaction is 30–100°C, preferably 50–80°C, more preferably 40–60°C; and / or the time of the coordination polymerization reaction is 4–12 h, preferably 4–10 h, more preferably 6–8 h.

[0032] The preferred method for preparing the bio-based low-temperature resistant elastomer of the present invention includes the following steps:

[0033] Under nitrogen or inert gas protection, neodymium carboxylate compound, alkyl aluminum, halogen-containing compound, and conjugated diene A are added sequentially to a vacuum reaction flask. The mixture is aged at 40–60°C for 40–60 min with stirring. Then, solvent, terpene compound, and conjugated diene are added, and polymerization is carried out at 30–100°C for 4–12 h. The reaction is then terminated by adding methanol. The polymer solution is poured off, and the copolymer is flocculated with methanol or ethanol. After vacuum drying, a bio-based low-temperature resistant elastomer is obtained.

[0034] The order in which neodymium carboxylate, alkyl aluminum, halogenated compound, and conjugated diene A are added to a neodymium-based catalyst system can affect the activity of the catalyst system. In this invention, the preferred order of addition is neodymium carboxylate, alkyl aluminum, halogenated compound, and conjugated diene A.

[0035] A third objective of this invention is to provide a rubber composition comprising either the bio-based low-temperature resistant elastomer of one objective of this invention or the bio-based low-temperature resistant elastomer prepared by the method of another objective of this invention.

[0036] The present invention can produce synthetic rubber by chemically crosslinking the bio-based low-temperature resistant elastomer, wherein the chemical crosslinking can be achieved through a traditional vulcanization system.

[0037] The rubber composition of the present invention may contain various commonly used additives in the art, such as zinc oxide, stearic acid, silica, silicon 69, accelerator CZ, accelerator DM, antioxidant 4020, sulfur, etc., and the dosages are conventional or may be adjusted according to actual requirements.

[0038] The fourth objective of this invention is to provide a method for preparing a rubber composition according to the third objective of this invention, comprising the step of mixing and vulcanizing components including the bio-based low-temperature resistant elastomer.

[0039] In the above preparation process, the mixing, compounding, and vulcanization of the raw material components can be carried out using conventional rubber processing techniques. The equipment used is also conventional rubber processing equipment, such as internal mixers, open mills, and flat vulcanizing machines.

[0040] Specifically, the preparation method includes mixing 100 parts by weight of a bio-based low-temperature resistant elastomer with rubber additives through a mixer and then performing compression molding and vulcanization at 140-160°C to obtain a rubber composite material.

[0041] The rubber additives mentioned are conventional additives in the prior art, and their dosage is also conventional. The inventors can add them according to the actual situation.

[0042] The fifth objective of this invention is to provide an application of a bio-based low-temperature resistant elastomer, which is one of the objectives of this invention, or a bio-based low-temperature resistant elastomer prepared by the method of another objective of this invention, in tires, especially in winter tires.

[0043] The beneficial effects of this invention are as follows:

[0044] The bio-based low-temperature resistant elastomer of the present invention has a high molecular weight, a high cis-1,4 structure content of 90-96%, a low glass transition temperature, and does not crystallize at low temperatures. Furthermore, its preparation process is simple.

[0045] This invention utilizes a neodymium-based catalyst system to catalyze the copolymerization of terpenoids and conjugated dienes to obtain high-molecular-weight bio-based low-temperature resistant elastomers. The terpenoid monomers used are primarily bio-based, aligning with current sustainable development principles. Furthermore, the side groups of the terpenoids can disrupt the crystallization of the molecular chains, simultaneously lowering the glass transition temperature of the bio-based low-temperature resistant elastomer. This glass transition temperature falls between -70°C and -60°C, resulting in excellent low-temperature resistance for the bio-based low-temperature resistant elastomer.

[0046] This invention, through rational structural design, regulates the structure of terpenoids and conjugated dienes, enabling bio-based low-temperature resistant elastomers to exhibit excellent low-temperature resistance, providing an effective approach for the preparation of winter tires.

[0047] This invention utilizes coordination polymerization to copolymerize myrcene and isoprene, controlling the microstructure of the copolymer to obtain a bio-based low-temperature resistant elastomer. The prepared bio-based low-temperature resistant elastomer has a narrow molecular weight distribution and a high cis-1,4 structure of 90–96%, meeting the requirements for low-temperature resistant elastomer applications. Attached Figure Description

[0048] Figure 1 The DSC curves obtained by differential scanning calorimetry (DSC) for the bio-based low-temperature resistant elastomers of Examples 1, 2, 3, 4, 5, and 6 are shown. Curves a, b, c, d, e, and f correspond in sequence to the following bio-based low-temperature resistant elastomers obtained in the examples: 1 (20% myrcene content in the comonomer), 2 (20% myrcene content in the comonomer), 3 (20% myrcene content in the comonomer), 4 (30% myrcene content in the comonomer), 5 (10% myrcene content in the comonomer), and 6 (40% myrcene content in the comonomer).

[0049] Figure 2 The NMR spectra of the bio-based low-temperature resistant elastomers from Examples 1, 2, 3, 4, 5, and 6 are shown in the figures. Curves 1, 2, 3, 4, 5, and 6 correspond sequentially to bio-based low-temperature resistant elastomers 1, 2, 3, 4, 5, and 6 obtained in the examples.

[0050] Figure 3 This is a comparison chart of the rate of change of rubber volume in Example 7, Comparative Example 1, and Comparative Example 2 at -25°C, measured using a capillary dilatometer. Detailed Implementation

[0051] The present invention will now be described in detail with reference to specific embodiments and accompanying drawings. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0052] All raw materials used in the examples are commercially available.

[0053] The models and manufacturers of the testing instruments used in this invention are shown in Table 1:

[0054] Table 1

[0055] Differential scanning calorimeter STARe Mettler-Tooledo, Switzerland Nuclear magnetic resonance spectrometer AV400 Bruker, Germany Gel permeation chromatography Waters1515 Waters Company, USA

[0056] The rubbers prepared in the examples and comparative examples were tested according to the following standards: tensile strength (GB / T 528-2009), stress at a given elongation (100%) (GB / T 528-2009), stress at a given elongation (300%) (GB / T 528-2009), elongation at break (GB / T528-2009), and cold resistance coefficient of compression (HG / T 3866-2008).

[0057] In the examples, the molar content of myrcene units and the ratio of 1,4 microstructures in the bio-based low-temperature resistant elastomers were obtained by NMR integration.

[0058] Example 1

[0059] The preparation method of bio-based low-temperature resistant elastomer 1 is carried out according to the following steps:

[0060] First, the vacuum reaction flask was dried and evacuated, then nitrogen gas was introduced to remove all oxygen and water. This cycle was repeated three times. Under nitrogen protection, 1 ml of neodymium neodecanoate in n-hexane (0.45 mol / L), 7 ml of diisobutylaluminum hydride in n-hexane (1 mol / L), 1 ml of diethylaluminum chloride in n-hexane (1 mol / L), and 0.005 mol of isoprene were added sequentially to the vacuum reaction flask. The mixture was aged at 50°C with stirring for 50 minutes to obtain the desired neodymium-based catalyst system. Under nitrogen protection, 10 g (0.073 mol) of myrcene, 20 g (0.294 mol) of isoprene, and 120 g of n-hexane were added. The reaction was carried out at 40°C for 4 hours, and then methanol was added to terminate the reaction. The polymer solution was poured out, and the copolymer was flocculated with methanol. The polymer was then dried in a vacuum oven to constant weight to obtain bio-based low-temperature resistant elastomer 1. Calculations showed a conversion rate of 96%, with a myrcene unit molar content of 25% and a cis-1,4 structure content of 94% in the copolymer. Gel permeation chromatography (GPC) determined the number-average molecular weight (Mn) of the bio-based low-temperature resistant elastomer 1 to be 9.2 × 10⁻⁶. 4 The molecular weight distribution coefficient (PDI) is 3.17.

[0061] Example 2

[0062] The preparation method of bio-based low-temperature resistant elastomer 2 is carried out according to the following steps:

[0063] First, the vacuum reaction flask was dried and evacuated, then nitrogen gas was introduced to remove all oxygen and water. This cycle was repeated three times. Under nitrogen protection, 1 ml of neodymium neodecanoate in n-hexane (0.45 mol / L), 7 ml of diisobutylaluminum hydride in n-hexane (1 mol / L), 1 ml of diethylaluminum chloride in n-hexane (1 mol / L), and 0.005 mol of isoprene were added sequentially to the vacuum reaction flask. The mixture was aged at 50°C with stirring for 50 minutes to obtain the desired neodymium-based catalyst system. Under nitrogen protection, 10 g (0.073 mol) of myrcene, 20.0 g (0.294 mol) of isoprene, and 120 g of n-hexane were added. The reaction was carried out at 50°C for 6 hours, and then methanol was added to terminate the reaction. The polymer solution was poured out, and the copolymer was flocculated with methanol. The polymer was then dried in a vacuum oven to constant weight to obtain bio-based low-temperature resistant elastomer 2. Calculations showed a conversion rate of 94%, with a myrcene unit molar content of 23% and a cis-1,4 structure content of 92% in the copolymer. Gel permeation chromatography (GPC) determined the number-average molecular weight (Mn) of the bio-based low-temperature resistant elastomer 2 to be 9.5 × 10⁻⁶. 4 The molecular weight distribution coefficient (PDI) is 3.12.

[0064] Example 3

[0065] The preparation method of bio-based low-temperature resistant elastomer 3 is carried out according to the following steps:

[0066] First, the vacuum reaction flask was dried and evacuated, then nitrogen was introduced to remove all oxygen and water. This cycle was repeated three times. Under nitrogen protection, 1 ml of neodymium neodecanoate in n-hexane (0.45 mol / L), 7 ml of triisobutylaluminum in n-hexane (1 mol / L), 1 ml of diethylaluminum chloride in n-hexane (1 mol / L), and 0.005 mol of isoprene were added sequentially to the vacuum reaction flask. The mixture was aged at 50°C with stirring for 50 minutes to obtain the desired neodymium-based catalyst system. Then, 10 g of myrcene, 20 g of isoprene, and 120 g of n-hexane were added under nitrogen protection. The reaction was carried out at 50°C for 6 hours, and then methanol was added to terminate the reaction. The polymer solution was poured out, and the copolymer was flocculated with methanol. The polymer was then dried in a vacuum oven to constant weight to obtain bio-based low-temperature resistant elastomer 3. The conversion rate was calculated to be 89%, the molar content of myrcene units in the copolymer was 23%, and the content of cis-1,4 structure was 91%. The number-average molecular weight (Mn) of the bio-based low-temperature resistant elastomer 3 was determined to be 12.3 × 10⁻⁶ by gel permeation chromatography (GPC). 4 The molecular weight distribution coefficient (PDI) is 2.17.

[0067] Example 4

[0068] The preparation method of bio-based low-temperature resistant elastomer 4 is carried out according to the following steps:

[0069] First, the vacuum reaction flask was dried and evacuated, then nitrogen gas was introduced to remove all oxygen and water. This cycle was repeated three times. Under nitrogen protection, 1 ml of neodymium neodecanoate in n-hexane (0.45 mol / L), 7 ml of triisobutylaluminum in n-hexane (1 mol / L), 1 ml of diethylaluminum chloride in n-hexane (1 mol / L), and 0.005 mol of isoprene were added sequentially to the vacuum reaction flask. The mixture was aged at 50°C with stirring for 50 minutes to obtain the desired neodymium-based catalyst system. Then, 13.7 g of myrcene, 16.0 g of isoprene, and 120 g of n-hexane were added under nitrogen protection. The reaction was carried out at 50°C for 6 hours, and then methanol was added to terminate the reaction. The polymer solution was poured out, and the copolymer was flocculated with methanol. The polymer was then dried in a vacuum oven to constant weight to obtain bio-based low-temperature resistant elastomer 4. Calculations showed a conversion rate of 92%, a myrcene unit molar content of 32% in the copolymer, and a cis-1,4 structure content of 93%. Gel permeation chromatography (GPC) determined the number-average molecular weight (Mn) of the bio-based low-temperature resistant elastomer 4 to be 11.7 × 10⁻⁶. 4 The molecular weight distribution coefficient (PDI) is 2.21.

[0070] Example 5

[0071] The preparation method of bio-based low-temperature resistant elastomer 5 is carried out according to the following steps:

[0072] First, the vacuum reaction flask was dried and evacuated, then nitrogen gas was introduced to remove all oxygen and water. This cycle was repeated three times. Under nitrogen protection, 1 ml of neodymium neodecanoate in n-hexane (0.45 mol / L), 7 ml of triisobutylaluminum in n-hexane (1 mol / L), 1 ml of sesquiethylaluminum chloride in n-hexane (1 mol / L), and 0.005 mol of isoprene were added sequentially to the vacuum reaction flask. The mixture was aged at 50°C with stirring for 50 minutes to obtain the desired neodymium-based catalyst system. Under nitrogen protection, 4.4 g (0.032 mol) of myrcene, 20.0 g (0.294 mol) of isoprene, and 120 g of n-hexane were added. The reaction was carried out at 60°C for 6 hours, and then methanol was added to terminate the reaction. The polymer solution was poured out, and the copolymer was flocculated with methanol. The polymer was then dried in a vacuum oven to constant weight to obtain bio-based low-temperature resistant elastomer 5. Calculations showed a conversion rate of 89%, a myrcene molar content of 13% in the copolymer, and a cis-1,4 structure content of 94%. Gel permeation chromatography (GPC) determined the number-average molecular weight (Mn) of the bio-based low-temperature resistant elastomer 5 to be 13.1 × 10⁻⁶. 4 The molecular weight distribution coefficient (PDI) is 2.18.

[0073] Example 6

[0074] The preparation method of bio-based low-temperature resistant elastomer 6 is carried out according to the following steps:

[0075] First, the vacuum reaction flask was dried and evacuated, then nitrogen gas was introduced to remove all oxygen and water. This cycle was repeated three times. Under nitrogen protection, 1 ml of neodymium neodecanoate in n-hexane (0.45 mol / L), 7 ml of triisobutylaluminum in n-hexane (1 mol / L), 1 ml of sesquiethylaluminum chloride in n-hexane (1 mol / L), and 0.005 mol of isoprene were added sequentially to the vacuum reaction flask. The mixture was aged at 50°C with stirring for 50 minutes to obtain the desired neodymium-based catalyst system. Under nitrogen protection, 20 g (0.147 mol) of myrcene, 15 g (0.22 mol) of isoprene, and 120 g of n-hexane were added. The reaction was carried out at 50°C for 6 hours, and then methanol was added to terminate the reaction. The polymer solution was poured out, and the copolymer was flocculated with methanol. The polymer was then dried in a vacuum oven to constant weight to obtain bio-based low-temperature resistant elastomer 6. Calculations showed a conversion rate of 89%, with a myrcene unit molar content of 44% and a cis-1,4 structure content of 93% in the copolymer. Gel permeation chromatography (GPC) determined the number-average molecular weight (Mn) of the bio-based low-temperature resistant elastomer 6 to be 12.1 × 10⁻⁶. 4 The molecular weight distribution coefficient (PDI) is 2.35.

[0076] from Figure 1 It can be seen that the glass transition temperature of bio-based low-temperature resistant elastomer 1 is -65.7℃, that of bio-based low-temperature resistant elastomer 2 is -65.50℃, that of bio-based low-temperature resistant elastomer 3 is -65.5℃, that of bio-based low-temperature resistant elastomer 4 is -66.1℃, that of bio-based low-temperature resistant elastomer 5 is -64.7℃, and that of bio-based low-temperature resistant elastomer 6 is -66.7℃. The glass transition temperatures of the bio-based low-temperature resistant elastomers prepared in the examples are all below -64℃. The myrcene content in the bio-based low-temperature resistant elastomer has a significant impact on the glass transition temperature. Temperature and time have no significant effect on the change in the glass transition temperature of the polymer. Moreover, when the content of the terpene compound—myrcene—in the comonomer is 5%-30%, the glass transition temperature of the polymer decreases with the increase of the myrcene content.

[0077] Example 7

[0078] The bio-based low-temperature resistant elastomer synthetic rubber prepared based on coordination polymerization is specifically calculated in parts by weight as follows:

[0079] 100 parts by weight of raw rubber (bio-based low-temperature resistant elastomer 5 (PIMy10%)), 60 parts by weight of silica (VN3), 6 parts by weight of silicon 69 (Si69), 5 parts by weight of zinc oxide, 2 parts by weight of stearic acid, 1 part by weight of antioxidant (4020), 1 part by weight of antioxidant (RD), 1 part by weight of accelerator (CZ), 1.2 parts by weight of accelerator (NS), and 1.5 parts by weight of sulfur.

[0080] Raw rubber was plasticized in an internal mixer for 1 min, then zinc oxide and stearic acid were added and mixed for 2 min. An antioxidant was added and mixed for 2 min, followed by the addition of silica and silicon 69 and mixing for 5 min. The mixture was then heat-treated at 150℃ for 5 min, cooled, and then accelerator and sulfur were added and mixed for 5 min to obtain the final rubber compound. The compound was then hot-pressed at 150℃ on a flat vulcanizing apparatus to prepare test samples. The tensile strength and elongation at break of the samples were measured. The performance test results are listed in Table 2.

[0081] Example 8

[0082] The bio-based low-temperature resistant elastomer synthetic rubber prepared based on coordination polymerization is specifically calculated in parts by weight as follows:

[0083] 100 parts by weight of raw rubber (bio-based low-temperature resistant elastomer 1 (PIMy20%)), 60 parts by weight of precipitated silica (VN3), 6 parts by weight of silicon 69 (Si69), 5 parts by weight of zinc oxide, 2 parts by weight of stearic acid, 1 part by weight of antioxidant (4020), 1 part by weight of antioxidant (RD), 1 part by weight of accelerator (CZ), 1.2 parts by weight of accelerator (NS), and 1.5 parts by weight of sulfur.

[0084] Raw rubber was plasticized in an internal mixer for 1 min, then zinc oxide and stearic acid were added and mixed for 2 min. An antioxidant was added and mixed for 2 min, followed by the addition of silica and silicon 69 and mixing for 5 min. The mixture was then heat-treated at 150℃ for 5 min, cooled, and then accelerator and sulfur were added and mixed for 5 min to obtain the final rubber compound. The compound was then hot-pressed at 150℃ on a flat vulcanizing apparatus to prepare test samples. The tensile strength and elongation at break of the samples were measured. The performance test results are listed in Table 2.

[0085] Example 9

[0086] The bio-based low-temperature resistant elastomer synthetic rubber prepared based on coordination polymerization is specifically calculated in parts by weight as follows:

[0087] 100 parts by weight of raw rubber (bio-based low-temperature resistant elastomer 4 (PIMy 30%)), 60 parts by weight of precipitated silica (VN3), 6 parts by weight of silicon 69 (Si69), 5 parts by weight of zinc oxide, 2 parts by weight of stearic acid, 1 part by weight of antioxidant (4020), 1 part by weight of antioxidant (RD), 1 part by weight of accelerator (CZ), 1.2 parts by weight of accelerator (NS), and 1.5 parts by weight of sulfur.

[0088] Raw rubber was plasticized in an internal mixer for 1 min, then zinc oxide and stearic acid were added and mixed for 2 min. An antioxidant was added and mixed for 2 min, followed by the addition of silica and silicon 69 and mixing for 5 min. The mixture was then heat-treated at 150℃ for 5 min, cooled, and then accelerator and sulfur were added and mixed for 5 min to obtain the final rubber compound. The compound was then hot-pressed at 150℃ on a flat vulcanizing apparatus to prepare test samples. The tensile strength and elongation at break of the samples were measured. The performance test results are listed in Table 2.

[0089] Example 10

[0090] The bio-based low-temperature resistant elastomer synthetic rubber prepared based on coordination polymerization is specifically calculated in parts by weight as follows:

[0091] 100 parts by weight of raw rubber (bio-based low-temperature resistant elastomer 6 (PIMy40%)), 60 parts by weight of silica (VN3), 6 parts by weight of silicon 69 (Si69), 5 parts by weight of zinc oxide, 2 parts by weight of stearic acid, 1 part by weight of antioxidant (4020), 1 part by weight of antioxidant (RD), 1 part by weight of accelerator (CZ), 1.2 parts by weight of accelerator (NS), and 1.5 parts by weight of sulfur.

[0092] Raw rubber was plasticized in an internal mixer for 1 min, then zinc oxide and stearic acid were added and mixed for 2 min. An antioxidant was added and mixed for 2 min, followed by the addition of silica and silicon 69 and mixing for 5 min. The mixture was then heat-treated at 150℃ for 5 min, cooled, and then accelerator and sulfur were added and mixed for 5 min to obtain the final rubber compound. The compound was then hot-pressed at 150℃ on a flat vulcanizing apparatus to prepare test samples. The tensile strength and elongation at break of the samples were measured. The performance test results are listed in Table 2.

[0093] Comparative Example 1

[0094] Styrene-butadiene rubber (ESBR1502) 100 parts by weight, silica (VN3) 60 parts by weight, silicon 69 (Si69) 6 parts by weight, zinc oxide 5 parts by weight, stearic acid 2 parts by weight, antioxidant (4020) 1 part by weight, antioxidant (RD) 1 part by weight, accelerator (CZ) 1 part by weight, accelerator (NS) 1.2 parts by weight, sulfur 1.5 parts by weight.

[0095] Raw rubber was plasticized in an internal mixer for 1 min, then zinc oxide and stearic acid were added and mixed for 2 min. An antioxidant was added and mixed for 2 min, followed by the addition of silica and silicon 69 and mixing for 5 min. The mixture was then heat-treated at 150℃ for 5 min, cooled, and then accelerator and sulfur were added and mixed for 5 min to obtain the final rubber compound. The compound was then hot-pressed at 150℃ on a flat vulcanizing apparatus to prepare test samples. The tensile strength and elongation at break of the samples were measured. The performance test results are listed in Table 2.

[0096] Comparative Example 2

[0097] 100 parts by weight of raw rubber (natural rubber NR), 60 parts by weight of silica (VN3), 6 parts by weight of silicon 69 (Si69), 5 parts by weight of zinc oxide, 2 parts by weight of stearic acid, 1 part by weight of antioxidant (4020), 1 part by weight of antioxidant (RD), 1 part by weight of accelerator (CZ), 1.2 parts by weight of accelerator (NS), and 1.5 parts by weight of sulfur.

[0098] Raw rubber was plasticized in an internal mixer for 1 min, then zinc oxide and stearic acid were added and mixed for 2 min. An antioxidant was added and mixed for 2 min, followed by the addition of silica and silicon 69 and mixing for 5 min. The mixture was then heat-treated at 150℃ for 5 min, cooled, and then accelerator and sulfur were added and mixed for 5 min to obtain the final rubber compound. The compound was then hot-pressed at 150℃ on a flat vulcanizing apparatus to prepare test samples. The tensile strength and elongation at break of the samples were measured. The performance test results are listed in Table 2.

[0099] Table 2. Performance test results of samples from Examples 7-10 and Comparative Examples 1-2

[0100]

[0101] Figure 3 This is a comparison graph showing the rate of change of rubber volume in Example 7, Comparative Example 1, and Comparative Example 2 at -25°C, measured using a capillary dilatometer. Because crystallization causes the rubber volume to shrink, and if there is no crystallization, the volume will not change. Therefore, [the following text is incomplete and requires further context to translate accurately]. Figure 3 It can be seen that at a low temperature (-25°C), the rubber of Comparative Example 2 crystallized, while the synthetic rubber of the bio-based low-temperature resistant elastomer prepared by coordination polymerization in Example 7 of the present invention and the rubber of Comparative Example 1 did not crystallize. Furthermore, the synthetic rubbers of the bio-based low-temperature resistant elastomers prepared by coordination polymerization in Examples 8-10 of the present invention also did not crystallize under these conditions.

[0102] The performance of the examples and comparative examples revealed that natural rubber has high tensile strength due to the presence of stretching crystals. However, at low temperatures, natural rubber (containing 97.7% 1,4 cis structure) slowly crystallizes, leading to hardening and decreased performance. While styrene-butadiene rubber (SBR) does not crystallize at low temperatures, its high glass transition temperature causes a decrease in performance, reflected in the compression set coefficient, which indicates a decline in compression rebound at low temperatures. In contrast, the bio-based low-temperature resistant elastomer in the embodiments of this invention exhibits a lower glass transition temperature with increasing myrcene content (a terpene compound). Furthermore, the synthetic rubber based on this bio-based low-temperature resistant elastomer does not show crystallization at low temperatures because the 1,4 cis structure content is between 90% and 96%. Moreover, the synthetic rubber based on this bio-based low-temperature resistant elastomer exhibits elongation at break and compression set coefficient comparable to natural rubber, and tensile strength and stress at a given elongation (100%) comparable to SBR, meeting application requirements while providing better low-temperature resistance.

Claims

1. A bio-based low-temperature resistant elastomer containing conjugated diene structural units and terpene compound structural units; The conjugated diene structural unit is shown in formula (I): (I), where, R1 is H or CH3; The terpene compound structural unit is at least one of the structural units shown in formula (II), formula (III), and formula (IV); (II)、 (III)、 (IV), Based on the total molar amount of conjugated diene structural units and terpene structural units (100%), the molar content of terpene structural units is 5-60%, and the molar content of conjugated diene structural units is 40-95%; the number-average molecular weight of the bio-based low-temperature resistant elastomer is 20,000-300,000, and the molecular weight distribution coefficient (PDI) is 2.0-4.

5. Random copolymers were obtained by coordination chain transfer polymerization of bio-based monomeric terpenoids and conjugated dienes in the presence of a neodymium-based catalyst system. The neodymium-based catalyst system comprises neodymium carboxylate, alkylaluminum, halogen-containing compounds, and conjugated diene A; The preparation method of the bio-based low-temperature resistant elastomer includes the following steps: Under nitrogen or inert gas protection conditions, neodymium carboxylate compounds, alkyl aluminum compounds, halogen-containing compounds, Conjugated diene A was added sequentially to a vacuum reaction flask and, under stirring, was reacted at 40–60 °C. Aging for 40-60 minutes, followed by the addition of solvent, terpenoids, and conjugated dienes, and incubation at 30-100°C. The polymerization was carried out for 4-12 hours, and then methanol was added to the reaction system to terminate the reaction. The polymer solution was poured out, and the copolymer was flocculated with methanol or ethanol. After vacuum drying, a bio-based low-temperature resistant elastomer was obtained.

2. The bio-based low-temperature resistant elastomer as described in claim 1, characterized in that: Based on the total molar amount of conjugated diene structural units and terpene structural units (100%), the molar content of terpene structural units is 5-50%, and the molar content of conjugated diene structural units is 50-95%; the number average molecular weight of the bio-based low-temperature resistant elastomer is 100,000-300,000, and the molecular weight distribution coefficient (PDI) is 2.0-3.

0.

3. The bio-based low-temperature resistant elastomer as described in claim 1, characterized in that: 90-96% of the structural units of the bio-based low-temperature resistant elastomer are 1,4 cis structures.

4. The bio-based low-temperature resistant elastomer as described in claim 1, characterized in that: 91-94% of the structural units of the bio-based low-temperature resistant elastomer are 1,4 cis structures.

5. A method for preparing a bio-based low-temperature resistant elastomer as described in any one of claims 1-4, comprising the step of carrying out a coordination polymerization reaction of a terpene compound and a conjugated diene in a solvent in the presence of a neodymium-based catalyst system.

6. The preparation method according to claim 5, characterized in that: The terpene compound is at least one of myrcene, β-farnesene, and ocimene; and / or, The conjugated diene is at least one of isoprene and butadiene; and / or... The solvent is at least one selected from n-hexane and cyclohexane; and / or, The molar amount of the terpene compound is 5% to 60% of the total molar amount of the terpene compound and the conjugated diene; and / or, The total mass ratio of the terpenoids and conjugated dienes to the solvent is 1:3~10.

7. The preparation method according to claim 6, characterized in that: The terpene compound is myrcene; and / or The molar amount of the terpene compound is 5% to 50% of the total molar amount of the terpene compound and the conjugated diene; and / or The total mass ratio of the terpenoids and conjugated dienes to the solvent is 1:4~10.

8. The preparation method according to claim 6, characterized in that: The molar amount of the terpene compound is 5% to 30% of the total molar amount of the terpene compound and the conjugated diene.

9. The preparation method according to claim 5, characterized in that: The neodymium-based catalyst system comprises a neodymium carboxylate compound, an alkyl aluminum compound, a halogenated compound, and a conjugated diene A.

10. The preparation method according to claim 9, characterized in that: The neodymium carboxylate compound is at least one selected from neodymium naphthenate, neodymium octanoate, neodymium decanoate, and neodymium neodecanoate; and / or, The alkylaluminum is at least one selected from trimethylaluminum, triethylaluminum, tripropylaluminum, triisobutylaluminum, diethylaluminum hydride, and diisobutylaluminum hydride; and / or, The halogen-containing compound is at least one selected from sesquiethylaluminum chloride, diethylaluminum chloride, dimethylchlorosilane, and dimethyldichlorosilane; and / or, The conjugated diene A is at least one selected from butadiene, isoprene, 1,3-pentadiene, and 1,3-hexadiene; and / or... The molar ratio of the neodymium carboxylate compound, alkylaluminum, halogen-containing compound, and conjugated diene A is 1:(10~30):(1~10):(5~20); and / or, The molar ratio of the neodymium carboxylate compound to the total molar amount of the terpene compound and the conjugated diene is 1.5 × 10⁻⁶. -4 ~1.5×10 -3 .

11. The preparation method according to claim 10, characterized in that: The conjugated diene A is at least one of butadiene and isoprene.

12. The preparation method according to claim 5, characterized in that: The temperature of the coordination polymerization reaction is 30~100℃; and / or the time of the coordination polymerization reaction is 4~12h.

13. The preparation method according to claim 12, characterized in that: The temperature of the coordination polymerization reaction is 50~80℃; and / or the time of the coordination polymerization reaction is 4~10h.

14. A rubber composition comprising the bio-based low-temperature resistant elastomer of any one of claims 1-4 or the bio-based low-temperature resistant elastomer prepared by the method of any one of claims 5-13.

15. A method for preparing a rubber composition as described in claim 14, comprising the step of mixing and vulcanizing components including the bio-based low-temperature resistant elastomer.

16. The application of a bio-based low-temperature resistant elastomer according to any one of claims 1-4 or a bio-based low-temperature resistant elastomer prepared by the method according to any one of claims 5-13 in a tire.

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