Squalene-based rubber antioxidant and method for preparing the same

Abstract

The application discloses a squalene-based rubber antioxidant and a preparation method thereof. The preparation method comprises the following steps: S1, dissolving squalene in an organic solvent, then adding m-chloroperbenzoic acid, and obtaining an epoxidized squalene solution after reaction; S2, adding an inorganic alkali solution into the above solution, separating and removing an aqueous phase, and then removing a solvent in an organic phase to obtain epoxidized squalene; S3, adding the epoxidized squalene into dimethylbenzene to dissolve, adding p-aminodiphenylamine and an organic amine catalyst, and heating in an inert gas atmosphere, and obtaining a squalene-based antioxidant solution after reaction, and finally removing the solvent and the catalyst to obtain the squalene-based rubber antioxidant. The prepared antioxidant has good compatibility with common non-polar rubber, has a plasticizing effect, is beneficial to rubber processing, can participate in a rubber vulcanization reaction, effectively reduces migration and precipitation of the antioxidant in a rubber product during storage and use, and effectively improves anti-aging performance of the rubber product.

Description

Technical Field

[0001] This invention relates to antioxidants for rubber materials, specifically to a squalene-based rubber antioxidant and its preparation method. Background Technology

[0002] Traditional engineering applications of rubber materials are mostly non-polar rubbers, including natural rubber, styrene-butadiene rubber, butadiene rubber, and nitrile rubber. Their polymer chain structure is mainly composed of carbon, hydrogen, and other elements. The polymer chain of rubber usually contains a large number of carbon-carbon double bonds. Its allyl hydrogen has high activity and is prone to aging under oxygen, ozone, light, and stress conditions, resulting in polymer chain breakage or cross-linking, causing the rubber product to lose its function. The traditional strategy to solve the aging problem of rubber products is to add anti-aging agents. This method has low impact on the rubber processing and production process and good economic performance. Therefore, such anti-aging agents have been well applied in the market. Anti-aging agents can be divided into: (1) amine anti-aging agents, common products include 6PPD, RD, 4010NA, etc.; (2) phenolic anti-aging agents, usually hindered phenolic anti-aging agents; (3) heterocyclic anti-aging agents; (4) phosphite anti-aging agents.

[0003] Currently, amine antioxidants are the most commonly used antioxidants in rubber products. Amine antioxidants can effectively eliminate active free radicals. Their research is relatively mature, and they have the most complete range of commercially available products at a low price. However, when traditional amine antioxidants are used in rubber products for a long time, due to their small molecular weight, the antioxidants tend to migrate out of the rubber matrix, causing the anti-aging performance of the rubber products to decline rapidly over time. In addition, some amine antioxidants have poor compatibility with non-polar rubbers, resulting in a decrease in the mechanical properties of the material. Summary of the Invention

[0004] To address the issues of poor compatibility with rubber materials and easy migration from the rubber matrix during long-term storage and use of the aforementioned amine antioxidants, this invention provides a squalene-based rubber antioxidant and its preparation method. The rubber antioxidant prepared by this method has good compatibility with rubber materials, can maintain the mechanical properties of the rubber materials themselves, and also has excellent anti-aging properties.

[0005] To achieve the above objectives, the present invention provides a method for preparing a squalene-based rubber antioxidant, characterized by comprising the following steps:

[0006] S1. Dissolve squalene in an organic solvent, then add m-chloroperoxybenzoic acid to cause the carbon-carbon double bonds in the squalene molecule to undergo an epoxidation reaction, resulting in an epoxidized squalene solution.

[0007] S2. Add an inorganic alkali solution to the above solution. The epoxidized squalene product dissolves in the organic phase, while the byproduct m-chlorobenzoic acid dissolves in the aqueous phase. Separate and remove the aqueous phase, and finally remove the solvent from the organic phase to obtain epoxidized squalene.

[0008] S3. Add epoxidized squalene to xylene (CAS No.: 1330-20-7) to dissolve, add p-aminodiphenylamine and organic amine catalyst, heat in an inert gas atmosphere to cause the epoxy groups to undergo a ring-opening reaction, and obtain a squalene-based antioxidant solution. Finally, remove the solvent and catalyst to obtain the squalene-based rubber antioxidant.

[0009] This invention uses squalene, m-chloroperoxybenzoic acid, and p-aminodiphenylamine as raw materials, and prepares a squalene-based antioxidant with excellent comprehensive performance based on the epoxidation reaction of carbon-carbon double bonds and the ring-opening reaction of amino-epoxy compounds. This squalene-based antioxidant contains p-phenylenediamine structural units, which have active free radical scavenging functions. The squalene-based antioxidant has a low molecular weight, is in an amorphous state, and has a low glass transition temperature, thus acting as a plasticizer, which is beneficial for the processing of rubber materials. Furthermore, the antioxidant contains multiple isoprene structural units, which can participate in the vulcanization of rubber materials, enabling the antioxidant to form covalent bonds with rubber polymers, effectively preventing the migration and precipitation of the antioxidant in rubber products. This squalene-based rubber antioxidant has low molecular polarity and good compatibility with non-polar rubbers, promoting the uniform dispersion of p-phenylenediamine structural units in the rubber matrix, thereby improving both the processing performance and the anti-aging properties of rubber products.

[0010] The above preparation method is simple, convenient to operate, and produces no byproducts. The prepared squalene-based rubber anti-aging agent contains p-phenylenediamine groups, which have the ability to eliminate active free radicals and have good anti-aging performance. The squalene-based anti-aging agent contains multiple isoprene structural groups, which can participate in the vulcanization reaction of traditional unsaturated rubber, thus solving the incompatibility problem between the anti-aging agent and non-polar rubber, preventing its migration and precipitation in the rubber body, and improving the comprehensive performance of rubber products.

[0011] Preferably, in step S1, the organic solvent is one or both of dichloromethane and chloroform.

[0012] Preferably, in step S1, the molar ratio of squalene to m-chloroperoxybenzoic acid is 1:(1~2).

[0013] Preferably, in step S1, the epoxidation reaction is carried out at a temperature of 0~30℃ and for a reaction time of 24~48h, under a nitrogen protective atmosphere.

[0014] In the above technical solution, the carbon-carbon double bond groups in squalene can fully react with m-chloroperoxybenzoic acid to generate epoxy groups.

[0015] Preferably, in step S2, the inorganic alkali solution is an aqueous solution of sodium carbonate or sodium bicarbonate, and the molar ratio of inorganic alkali to m-chloroperoxybenzoic acid is (2~3):1.

[0016] In the above technical solution, the generated byproduct m-chlorobenzoic acid can be fully transferred to the aqueous phase, which is beneficial for obtaining pure epoxidized squalene after solvent separation in the organic phase.

[0017] Preferably, in step S3, the catalyst is 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), and the molar ratio of 1,8-diazabicyclo[5.4.0]undec-7-ene to epoxidized squalene is (0.1~0.3):1.

[0018] Preferably, in step S3, the molar ratio of the epoxy groups in p-aminodiphenylamine to epoxidized squalene is 1:1.

[0019] Preferably, in step S3, the ring-opening reaction is carried out at a temperature of 100-120°C for 24-48 hours.

[0020] In the above technical solution, DBU mainly plays a role in catalyzing the ring-opening reaction between the amino group and the epoxy group in p-aminodiphenylamine.

[0021] The second aspect of the present invention provides a squalene-based rubber antioxidant prepared by the above-described preparation method.

[0022] Through the above technical solution, the present invention achieves the following beneficial effects:

[0023] 1. Compared with traditional antioxidants, the squalene-based rubber antioxidant prepared by this invention using industrial raw materials has good compatibility with commonly used non-polar rubbers. At the same time, the antioxidant participates in the rubber vulcanization reaction, reducing the migration and precipitation of the antioxidant during storage and use.

[0024] 2. The preparation method of the rubber antioxidant proposed in this invention is convenient and easy to implement, and the prepared antioxidant has excellent long-term anti-aging performance. This antioxidant has a wide range of applications. Attached Figure Description

[0025] Figure 1 This is a schematic diagram illustrating the synthesis reaction principle of squalene-based rubber antioxidant in this embodiment of the invention. Detailed Implementation

[0026] The specific embodiments of the present invention will be described in detail below with reference to examples. 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.

[0027] Unless otherwise specified, all reagents used in the following examples are commercially available products.

[0028] Example 1

[0029] like Figure 1 As shown, the preparation method of squalene rubber antioxidant is as follows:

[0030] (1) Add 10g of squalene to 200ml of chloroform, then add 4.19g of m-chloroperoxybenzoic acid. Control the reaction temperature at 30℃ and stir for 24h.

[0031] (2) Add 400 ml of sodium carbonate aqueous solution with a concentration of 12.93 g / L to the mixture, stir for 20 min and let stand for 5 min, then use a separatory funnel to separate and remove the aqueous phase, and finally use a rotary evaporator at 30 °C to remove the solvent in the organic phase to obtain 10.37 g of epoxidized squalene.

[0032] (3) 10.37g of epoxidized squalene was added to 200ml of xylene and dissolved. 4.46g of p-aminodiphenylamine and 1.01g of DBU were added. The temperature was raised to 100℃ and stirred in a nitrogen atmosphere for 48h to allow the epoxy groups to undergo a ring-opening reaction, thereby obtaining a squalene-based antioxidant solution. Finally, the solvent and catalyst were removed by rotary evaporation to obtain the squalene-based rubber antioxidant.

[0033] Example 2

[0034] The preparation method of squalene rubber antioxidant is as follows:

[0035] (1) Add 10g of squalene to 200ml of chloroform, then add 8.38g of m-chloroperoxybenzoic acid. Control the reaction temperature at 0℃ and stir for 48h.

[0036] (2) Add 400 ml of sodium carbonate aqueous solution with a concentration of 35.85 g / L to the mixture, stir for 20 min and let stand for 5 min, then use a separatory funnel to separate and remove the aqueous phase, and finally use a rotary evaporator at 30 °C to remove the solvent in the organic phase to obtain 10.75 g of epoxidized squalene.

[0037] (3) 10.75g of epoxidized squalene was added to 200ml of xylene and dissolved. 8.92g of p-aminodiphenylamine and 1.48g of DBU were added. The temperature was raised to 120℃ and stirred for 24h in a nitrogen atmosphere to allow the epoxy groups to undergo a ring-opening reaction, thereby obtaining a squalene-based antioxidant solution. Finally, the solvent and catalyst were removed by rotary evaporation to obtain the squalene-based rubber antioxidant.

[0038] Example 3

[0039] The preparation method of squalene rubber antioxidant is as follows:

[0040] (1) Add 10g of squalene to 200ml of chloroform, then add 6.29g of m-chloroperoxybenzoic acid. Control the reaction temperature at 0℃ and stir for 48h.

[0041] (2) Add 400 ml of sodium bicarbonate aqueous solution with a concentration of 30.72 g / L to the mixture, stir for 20 min and let stand for 5 min, then use a separatory funnel to separate and remove the aqueous phase, and finally use a rotary evaporator at 30 °C to remove the solvent in the organic phase to obtain 10.56 g of epoxidized squalene.

[0042] (3) 10.56g of epoxidized squalene was added to 200ml of xylene and dissolved. 6.71g of p-aminodiphenylamine and 1.66g of DBU were added. The temperature was raised to 110℃ and stirred for 36h in a nitrogen atmosphere to allow the epoxy groups to undergo a ring-opening reaction, thereby obtaining a squalene-based antioxidant solution. Finally, the solvent and catalyst were removed by rotary evaporation to obtain the squalene-based rubber antioxidant.

[0043] Example 4

[0044] The preparation method of squalene rubber antioxidant is as follows:

[0045] (1) Add 10g squalene to 200ml dichloromethane, then add 5.45g m-chloroperoxybenzoic acid, control the reaction temperature at 15℃, and stir the reaction for 36h.

[0046] (2) Add 400 ml of sodium bicarbonate aqueous solution with a concentration of 24.85 g / L to the mixture, stir for 20 min and let stand for 5 min, then use a separatory funnel to separate and remove the aqueous phase, and finally use a rotary evaporator at 30 °C to remove the solvent in the organic phase to obtain 10.49 g of epoxidized squalene.

[0047] (3) 10.49 g of epoxidized squalene was added to 200 ml of xylene to dissolve, 5.81 g of p-aminodiphenylamine and 1.78 g of DBU were added, the temperature was raised to 110 °C, and the reaction was stirred in a nitrogen atmosphere for 48 h to allow the epoxy groups to undergo a ring-opening reaction, thereby obtaining a squalene-based antioxidant solution. Finally, the solvent and catalyst were removed by rotary evaporation to obtain the squalene-based rubber antioxidant.

[0048] Example 5

[0049] The preparation method of squalene rubber antioxidant is as follows:

[0050] (1) Add 10g squalene to 200ml dichloromethane, then add 7.14g m-chloroperoxybenzoic acid, control the reaction temperature at 20℃, and stir the reaction for 24h.

[0051] (2) Add 400 ml of sodium bicarbonate aqueous solution with a concentration of 28.58 g / L to the mixture, stir for 20 min and let stand for 5 min, then use a separatory funnel to separate and remove the aqueous phase, and finally use a rotary evaporator at 30 °C to remove the solvent in the organic phase to obtain 10.69 g of epoxidized squalene.

[0052] (3) 10.69 g of epoxidized squalene was added to 200 ml of xylene to dissolve, 4.46 g of p-aminodiphenylamine and 1.33 g of DBU were added, the temperature was raised to 105 °C, and the reaction was stirred in a nitrogen atmosphere for 48 h to allow the epoxy groups to undergo a ring-opening reaction, thereby obtaining a squalene-based antioxidant solution. Finally, the solvent and catalyst were removed by rotary evaporation to obtain the squalene-based rubber antioxidant.

[0053] Example 6

[0054] The preparation method of squalene rubber antioxidant is as follows:

[0055] (1) Add 10g squalene to 200ml dichloromethane, then add 8.39g m-chloroperoxybenzoic acid, control the reaction temperature at 15℃, and stir the reaction for 36h.

[0056] (2) Add 400 ml of sodium bicarbonate aqueous solution with a concentration of 39.93 g / L to the mixture, stir for 20 min and let stand for 5 min, then use a separatory funnel to separate and remove the aqueous phase, and finally use a rotary evaporator at 30 °C to remove the solvent in the organic phase to obtain 10.75 g of epoxidized squalene.

[0057] (3) 10.75g of epoxidized squalene was added to 200ml of xylene and dissolved. 8.92g of p-aminodiphenylamine and 1.44g of DBU were added. The temperature was raised to 115℃ and stirred in a nitrogen atmosphere for 48h to allow the epoxy groups to undergo a ring-opening reaction, thereby obtaining a squalene-based antioxidant solution. Finally, the solvent and catalyst were removed by rotary evaporation to obtain the squalene-based rubber antioxidant.

[0058] Performance testing

[0059] Using styrene-butadiene rubber as the rubber matrix, and traditional p-phenylenediamine-based rubber antioxidants, specifically antioxidant 4020 as the reference sample, the p-phenylenediamine content in the synthesized squalene-based antioxidants is relatively low. For ease of comparison, the p-phenylenediamine group content in the antioxidant structure of different samples is kept basically consistent.

[0060] The formulations of styrene-butadiene rubber in Examples A1-A6 are as follows: styrene-butadiene rubber: 100; prepared squalene-based antioxidant: 5; carbon black (N330): 30; zinc oxide: 5.0; stearic acid: 2.0; accelerator CZ: 1.8; sulfur: 2.5.

[0061] Comparative Example 1 (A01):

[0062] The procurement method was adopted to purchase commonly used p-phenylenediamine rubber antioxidants on the market, specifically antioxidant 4020.

[0063] The styrene-butadiene rubber (SBR) formulation is as follows:

[0064] Styrene-butadiene rubber: 100; Antioxidant 4020: 2; Carbon black (N330): 30; Zinc oxide: 5.0; Stearic acid: 2.0; Accelerator CZ: 1.8; Sulfur: 2.5.

[0065] Comparative Example 2 (A02):

[0066] No antioxidants added.

[0067] The styrene-butadiene rubber (SBR) formulation is as follows:

[0068] Styrene-butadiene rubber: 100; Carbon black (N330): 30; Zinc oxide: 5.0; Stearic acid: 2.0; Accelerator CZ: 1.8; Sulfur: 2.5.

[0069] Rubber was mixed using an open mill with the rollers at room temperature, and cooling water was required during the mixing process. The styrene-butadiene rubber (SBR) was first plasticized several times. Then, stearic acid, zinc oxide, the prepared antioxidant, accelerator, and vulcanizing agent were added to the compound. The mixture was then re-mixed, rolled, and finally sheeted after four triangular wraps and thin passes. After resting for one day, the sample was re-mixed three times on the open mill, sheeted, and vulcanized using a flatbed press at 150℃ and 20MPa to obtain the SBR sample.

[0070] The heat and oxygen aging resistance was tested according to GB / T13939-2014 standard. The temperature of the aging chamber was 100℃, the sample was suspended vertically in the aging chamber, and the hot air inside the chamber was circulated.

[0071] The mechanical properties of the rubber samples were determined in accordance with GB / T528-2009 Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber. Dumbbell-shaped specimens were prepared and the tensile rate was 500 mm / min.

[0072] The formula for calculating the retention rate of tensile strength and elongation at break of rubber after aging is: tensile strength or elongation at break of aged sample / tensile strength and elongation at break of sample before aging * 100%.

[0073] The test results for some samples are shown in Table 1.

[0074] Table 1 Test results of anti-aging properties of styrene-butadiene rubber

[0075]

[0076] As shown in Table 1, compared with the addition of traditional antioxidants, the anti-aging performance of styrene-butadiene rubber products was significantly improved by adding the squalene-based antioxidants prepared in Examples A1-A6. Compared with the addition of traditional antioxidant 4020, the mechanical strength and elongation at break of the samples were improved by adding the squalene-based antioxidant prepared in this invention. The aging test results show that the tensile properties and elongation at break of the styrene-butadiene rubber samples after aging with the squalene-based antioxidant of this invention are significantly better than those of styrene-butadiene rubber with traditional antioxidant 4020 (Comparative Example A01), and also better than those of styrene-butadiene rubber without antioxidant (Comparative Example A02). This is mainly attributed to the good compatibility between the squalene-based antioxidant prepared in this patent and styrene-butadiene rubber. When the amount added is small, it has virtually no impact on the mechanical properties of the rubber product. In addition, the isoprene structural unit in the molecular structure of the squalene-based antioxidant prepared in this patent also participates in the vulcanization reaction of the rubber, so that the prepared squalene-based antioxidant forms covalent bonds with the rubber polymer chain, effectively preventing the migration and precipitation of the antioxidant during the aging test, thereby improving the anti-aging performance of the rubber product.

[0077] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0078] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0079] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A method for preparing a squalene-based rubber antioxidant, characterized in that, Includes the following steps: S1. Dissolve squalene in an organic solvent, then add m-chloroperoxybenzoic acid to cause an epoxidation reaction of the carbon-carbon double bonds in the squalene molecule, yielding an epoxidized squalene solution. The reaction formula is as follows: ； S2. Add an inorganic alkali solution to the above solution. The epoxidized squalene product dissolves in the organic phase, while the byproduct m-chlorobenzoic acid dissolves in the aqueous phase. Separate and remove the aqueous phase, and finally remove the solvent from the organic phase to obtain epoxidized squalene. S3. Add epoxidized squalene to xylene to dissolve, add p-aminodiphenylamine and organic amine catalyst, heat in an inert gas atmosphere to cause the epoxy groups to undergo a ring-opening reaction, and obtain a squalene-based antioxidant solution. Finally, remove the solvent and catalyst to obtain the squalene-based rubber antioxidant.

2. The preparation method according to claim 1, characterized in that, In step S1, the organic solvent is one or both of dichloromethane and chloroform.

3. The preparation method according to claim 1, characterized in that, In step S1, the molar ratio of squalene to m-chloroperoxybenzoic acid is 1:(1~2).

4. The preparation method according to claim 1, characterized in that, In step S1, the epoxidation reaction is carried out at a temperature of 0~30℃ for 24~48h, and the reaction is carried out in a nitrogen protective atmosphere.

5. The preparation method according to claim 1, characterized in that, In step S2, the inorganic alkali solution is an aqueous solution of sodium carbonate or sodium bicarbonate, and the molar ratio of inorganic alkali to m-chloroperoxybenzoic acid is (2~3):

1.

6. The preparation method according to claim 1, characterized in that, In step S3, the catalyst is 1,8-diazabicyclo[5.4.0]undec-7-ene, and the molar ratio of 1,8-diazabicyclo[5.4.0]undec-7-ene to epoxidized squalene is (0.1~0.3):

1.

7. The preparation method according to claim 1, characterized in that, In step S3, the molar ratio of the epoxy groups in p-aminodiphenylamine to epoxidized squalene is 1:

1.

8. The preparation method according to claim 1, characterized in that, In step S3, the ring-opening reaction is carried out at a temperature of 100-120°C for 24-48 hours.

9. The squalene-based rubber antioxidant prepared by any one of claims 1 to 8.

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