Bio-based ester softener modified rubber composition as well as preparation and application thereof

Abstract

The invention discloses a bio-based ester softener modified rubber composition as well as preparation and application thereof, and belongs to the technical field of polymer processing aids. The rubber composition is prepared from the following raw materials in parts by weight: 80 to 120 parts of raw rubber, 20 to 50 parts of filler, 1 to 30 parts of bio-based ester softener and 1 to 5 parts of functional additive. The adopted structure is as shown in the specification, and the softening agent is high in boiling point, good in stability, non-toxic, green and environment-friendly, and is a perfect substitute of a traditional benzene softening agent. When the softening agent is applied to a rubber material, the mechanical property of the rubber material is enhanced, the hardness and Mooney viscosity are reduced, and the compatibility of the plasticized rubber material is improved, so that the plasticized rubber material has excellent processability.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer processing aids, and in particular relates to a bio-based ester softener modified rubber composition and a preparation method and application thereof. Background Art

[0002] With the vigorous development of new energy vehicles, aviation and petroleum industries, the market demand for rubber products shows a trend of sustained growth. However, these rubber materials have poor brittleness and aging resistance, which is not conducive to long-term use, and softeners need to be added to improve their processing performance. The addition of rubber softeners can improve the interface between fillers and rubber, reduce intermolecular forces, and increase the compatibility between rubber and fillers. At the same time, as a rubber additive, it can also adjust the vulcanization time and scorch time of rubber, which helps people control the preparation process of rubber products, so that rubber products can be prepared using a variety of methods and equipment, reducing energy consumption in the production process while ensuring processing safety. Rubber softeners are mainly phthalates represented by dioctyl phthalate (DOP). However, phthalate softeners are easy to migrate out of rubber during use, producing highly toxic substances that are seriously harmful to the human body. Other softeners are mostly petroleum-based low molecular weight hydrocarbon oil products, which are not conducive to the protection of the ecological environment and non-renewable resources. Therefore, the use of biomass resources to develop green new bio-based softeners has huge market prospects and important practical significance for enriching the varieties of softeners, promoting the replacement of bio-based softeners for traditional petroleum-based softeners, gradually expanding the scope of use of bio-based softeners, and adapting to the future development trend of the polymer material functional additives industry.

[0003] Fatty acid ester is one of the derivatives of oils and fats. It has long been a hot topic of research because it can be used as automobile fuel. When used as a softener for rubber materials, it has the following problems: low boiling point leads to easy volatility during processing; large addition leads to a serious decrease in the tensile strength of the product; poor compatibility leads to easy migration and precipitation on the surface. It can only be added in small amounts as an auxiliary softener.

[0004] CN117986692A discloses an acetoxy fatty acid methyl ester environmentally friendly softener, which is prepared by sulfonating refined diesel with sulfuric acid and then hydrolyzing it to obtain a mixture containing hydroxy fatty acid methyl esters; then acetylation reaction is carried out with acetic anhydride under the action of a catalyst to obtain a mixture containing acetoxy fatty acid methyl esters; after purification, standing and stratifying to obtain an upper oil layer; and washing the oil layer to obtain. However, the acetoxy fatty acid methyl ester environmentally friendly softener has low thermal stability and insufficient mechanical properties.

[0005] CN110627643A discloses an environmentally friendly softener product, acetyl fatty acid methyl ester-trimellitic acid ester, which uses higher fatty acids purified from waste oils, methanol, 50% hydrogen peroxide, trimellitic anhydride and acetic anhydride as main raw materials, and transforms the molecular structure and functional group through four-step reactions of esterification, epoxidation, ring-opening esterification and acetylation. The environmentally friendly softener has the characteristics of a combination of cyclic molecules and linear molecules at the same time, the product has moderate viscosity, yellow color, good migration resistance and heat resistance, is suitable for industrial production, and is expected to replace traditional phthalate softeners. However, this type of softener is a tribasic acid ester structure with a relatively large molecular weight, and the tribasic ester structure has a large steric hindrance, so the obtained plasticized product has strong rigidity, poor flexibility, and insufficient mechanical properties; and trimellitic anhydride is not a bio-based raw material, so the obtained softener has a relatively large molecular weight and a relatively large viscosity. Summary of the invention

[0006]

Technical issues

[0007] The invention solves the problems of poor compatibility, high viscosity, insufficient thermal stability and mechanical properties of rubber products using existing softeners.

[0008]

Technical solution

[0009] The invention provides a bio-based ester softener and a rubber composition and application thereof. The rubber composition of the invention has excellent plasticizing effect and maintains good mechanical properties.

[0010] The present invention adopts a novel bio-based ester rubber softener, which is prepared by using fatty acid ester, natural organic acid and acetic anhydride as raw materials to obtain a bio-based ester softener with excellent performance. The structure contains a long fatty chain structure, a benzene ring structure, a multi-ester structure and a short ester branched structure, so it has special plasticizing properties.

[0011] The first object of the present invention is to provide a rubber composition, the raw materials of which include 80-120 parts by weight of raw rubber, 20-50 parts by weight of filler, 1-30 parts by weight of bio-based ester softener, and 1-5 parts by weight of functional additive;

[0012] The structure of the bio-based ester softener is shown in formula (A1), (A2), or (A3):

[0013]

[0014] In the formula, R 1 C 1-10 alkyl;

[0015] n1 is -CH on the fatty chain 2 - is 1, 2, 3, 4, 5, 6, 7 or 8;

[0016] n2 is a substituent R on the benzene ring 2 The number of substitutions is 1, 2, 3 or 4;

[0017] Each R 2 are independently selected from -O-C1-4 alkyl, -O-CO-C 1-4 alkyl;

[0018] n3 is -CH on the fatty chain 2 - is 1, 2, 3, 4, 5, 6, 7 or 8;

[0019] n4 is -CH on the fatty chain 2 - is 1, 2, 3, 4, 5, 6, 7 or 8;

[0020] n5 is -CH on the fatty chain 2 - is 1, 2, 3, 4, 5, 6, 7 or 8.

[0021] In an embodiment of the present invention, there is at least one -O-CO-C 1-4 Alkyl substitution.

[0022] In an embodiment of the present invention, the structure of the bio-based ester softener may be:

[0023]

[0024] R 1 is methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, pentyl, hexyl, heptyl, octyl, decyl;

[0025] R 2 , R 3 , R 4 , R 5 Each of them is independently selected from methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, tert-butoxy, acetoxy, propionyloxy and butyryloxy; and the rest are hydrogen.

[0026] In an embodiment of the present invention, R 2 , R 3 , R 4 , R 5 At least one of them is selected from -O-CO-C 1-4 Alkyl substituted; the rest are arbitrarily selected from: hydrogen, -O-C1-4 alkyl, or -O-CO-C 1-4 Alkyl substitution.

[0027] In an embodiment of the present invention, further, R 2 , R 3 , R4 , R 5 At least one of them is selected from acetoxy; the rest are hydrogen or methoxy.

[0028] In one embodiment of the present invention, the preparation method of the bio-based ester softener is as follows: first, fatty acid ester and catalyst 1 are used as raw materials to prepare epoxy fatty acid ester through epoxidation reaction; then, epoxy fatty acid ester, natural organic acid and ring-opening agent are subjected to ring-opening reaction to prepare fatty acid ester-organic acid ester; finally, fatty acid ester-organic acid ester, acetic anhydride and catalyst 2 are subjected to acetylation reaction to obtain bio-based ester softener.

[0029] In one embodiment of the present invention, the fatty acid ester is a fatty acid ester containing 1 to 3 unsaturated double bonds, specifically selected from: at least one of methyl oleate, ethyl oleate, butyl oleate, hexyl oleate, octyl oleate, decyl oleate, methyl linoleate, ethyl linoleate, butyl linoleate, hexyl linoleate, octyl linoleate, decyl linoleate, methyl linoleate, ethyl linoleate, butyl linoleate, hexyl linoleate, octyl linoleate, decyl linoleate, methyl linoleate, ethyl linoleate, butyl linoleate, hexyl linoleate, octyl linoleate and decyl linoleate.

[0030] In one embodiment of the present invention, the natural organic acid is at least one of salicylic acid, vanillic acid, syringic acid, gentisic acid, protocatechuic acid and gallic acid.

[0031] In an embodiment of the present invention, the catalyst 1 is any one of meta-chloroperbenzoic acid and hydrogen peroxide.

[0032] In an embodiment of the present invention, the ring-opening agent is any one of tetrabutylammonium chloride and tetrabutylammonium bromide.

[0033] In an embodiment of the present invention, the catalyst 2 is any one of a strongly acidic cation exchange resin and concentrated sulfuric acid.

[0034] In one embodiment of the present invention, in the epoxidation reaction, the molar ratio of the fatty acid ester to the catalyst 1 is 1:1.2-3.2.

[0035] In one embodiment of the present invention, the specific steps of the epoxidation reaction are: dissolving fatty acid ester and m-chloroperbenzoic acid in dichloromethane, reacting them in an ice-water bath and then at room temperature, neutralizing, purifying and drying to obtain the product epoxy fatty acid ester.

[0036] In one embodiment of the present invention, the specific steps of the epoxidation reaction are: adding an acidic ion exchange resin and formic acid to a fatty acid ester, and then dropping hydrogen peroxide to react to obtain an epoxy fatty acid ester.

[0037] In one embodiment of the present invention, the specific steps of the ring-opening reaction are: reacting the epoxy fatty acid ester, organic acid and ring-opening agent at 120-140° C. for 4-7 hours, washing to neutrality after the reaction, purifying and drying to obtain fatty acid ester-organic acid ester.

[0038] In one embodiment of the present invention, in the ring-opening reaction, the molar ratio of epoxy fatty acid ester to natural organic acid is 1:1.4-4.5.

[0039] Furthermore, if the fatty acid ester is a fatty acid ester containing one unsaturated double bond, the molar ratio of the epoxy fatty acid ester to the natural organic acid is 1:1.4-2.5; if the fatty acid ester is a fatty acid ester containing two unsaturated double bonds, the molar ratio of the epoxy fatty acid ester to the natural organic acid is 1:2.0-3.5; if the fatty acid ester is a fatty acid ester containing three unsaturated double bonds, the molar ratio of the epoxy fatty acid ester to the natural organic acid is 1:3.0-4.5.

[0040] In an embodiment of the present invention, during the ring-opening reaction, the amount of the ring-opening agent added is 0.1 wt%-5 wt% of the mass of the epoxy fatty acid ester, and can further be 4 wt%-5 wt%.

[0041] In one embodiment of the present invention, the specific steps of the acetylation reaction are: reacting acetic anhydride, fatty acid ester-organic acid ester and catalyst at 60°C-90°C for 10-24 hours, washing to neutrality after the reaction, purifying and drying to obtain a fatty acid ester-based softener.

[0042] In one embodiment of the present invention, in the acetylation reaction, the amount of acetic anhydride added is 50%-90% of the fatty acid ester-organic acid ester.

[0043] In an embodiment of the present invention, in the acetylation reaction, the added amount of the catalyst 2 is 5 wt % to 15 wt % of the fatty acid ester-organic acid ester.

[0044] In one embodiment of the present invention, the raw rubber is any one of nitrile rubber (NBR), chloroprene rubber (CR), fluororubber (FKM) and polyurethane rubber (PUR).

[0045] In one embodiment of the present invention, the filler is selected from any one or more of the following: carbon black, white carbon black, calcium carbonate, talc, barium sulfate, and montmorillonite.

[0046] In one embodiment of the present invention, the functional additive is selected from any one or more of the following: a cross-linking agent, an antioxidant, a vulcanizing agent, an accelerator, a lubricant, a scorch retarder, and a release agent.

[0047] A second object of the present invention is to provide a method for preparing a rubber composition, comprising the following steps:

[0048] (1) Plasticize the raw rubber for 10-20 minutes, with a roller distance of 3-4 mm, and thin pass 2-5 times;

[0049] (2) adding fillers, bio-based ester softeners, and functional additives according to the weight proportions in claim 1, and blending and kneading for 10-15 minutes, with a roller distance of 1-2 mm, and thin-passing 2-5 times to obtain a rubber mixture;

[0050] (3) The mixed rubber is rolled into a sheet, placed in a mold for compression molding and vulcanization to obtain a rubber composition.

[0051] In one embodiment of the present invention, the temperature of mastication is 50-60°C, the temperature of blending and kneading is 70-80°C, and the temperature of vulcanization is 170°C.

[0052] The present invention also provides application of the rubber composition in new energy vehicles, aviation and petroleum industries.

[0053]

Beneficial Effects

[0054] (1) The present invention prepares a softener having a long fatty chain structure, a benzene ring structure, a polyester structure, and a short ester branched structure; the softener is applied to a rubber material to improve the compatibility of the plasticized rubber material so that it has excellent processing performance, and the tensile strength, elongation at break, thermal stability, and migration resistance of the plasticized rubber material are better than those of the plasticized rubber material plasticized by an orthophthalic softener.

[0055] (2) The bio-based softener prepared by the present invention enters between rubber molecular chains, only improving the mobility of the molecular chains, without destroying the chain segments between macromolecules, and maintaining good tensile strength of the composite material. The presence of more polar groups in the softener enhances the compatibility between the softener and the rubber matrix, effectively reduces the interaction force between the rubber molecular chains, and makes the rubber molecular chains easier to slide, thereby enhancing the mechanical properties of the rubber material, reducing the hardness and Mooney viscosity, and improving the processing performance of the rubber material. It can replace traditional phthalate softeners.

[0056] (3) The raw materials used in the present invention are derived from new bio-based materials, which are green and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 This is the infrared spectrum of softener 1 methyl acetyloleate-salicylate product;

[0058] Figure 2The thermogravimetric curves of softener 1 acetyl oleate methyl salicylate and comparative softeners; the comparative softeners include: methyl oleate, softener A (benzyl oleate), softener B (acetoxy fatty acid methyl ester) and softener C (acetyl oleate methyl benzoate). DETAILED DESCRIPTION

[0059] The present invention is described in detail below in conjunction with the accompanying drawings and embodiments.

[0060] Preparation of a series of bio-based ester softeners

[0061] Preparation of Softener 1:

[0062] (R 1 =Me, R 2 =-O-COCH 3 , R 3 =R 4 =R 5 =H)

[0063] (1) 37 g of m-chloroperbenzoic acid was dissolved in 150 mL of dichloromethane and stirred under ice-water bath conditions, and then 100 mL of dichloromethane solution containing 50 g of methyl oleate was added dropwise to the above system, and the above raw materials were first reacted in an ice-water bath for 0.5 h, and then reacted at room temperature for 24 h. After the reaction, the mixture was washed with sodium thiosulfate solution and sodium bicarbonate solution until neutral, and then washed with sodium chloride solution for 3 times, and finally washed with deionized water for 3 times, and then dichloromethane was removed by vacuum distillation at -0.1 MPa and 35° C. to obtain the product epoxy methyl oleate;

[0064] (2) adding 50 g (0.16 mol) of the product methyl oleate obtained in step (1), 33 g (0.24 mol) of salicylic acid and 2 g of tetrabutylammonium chloride into a reactor under a nitrogen atmosphere, mixing the above raw materials and heating them to 140° C., and continuing the reaction for 5 h. After the reaction is completed, washing with deionized water until neutral, and then vacuum distilling the organic phase under -0.1 MPa and 75° C. to remove water to obtain the product methyl oleate-salicylate;

[0065] (3) Add 50 g of the product of step (2), 35 g of acetic anhydride and 2.5 g of a strongly acidic cation exchange resin into a reactor, mix the above raw materials, heat to 85° C., and continue the reaction for 24 hours. After the reaction is completed, first remove the acetic anhydride by vacuum distillation at -0.1 MPa and 120° C., then wash with deionized water to neutrality, and then remove the water by vacuum distillation at -0.1 MPa and 75° C. to obtain the final product, a bio-based ester softener, acetyl oleate methyl salicylate.

[0066] The infrared spectrum test of the product acetyloleate methyl salicylate in the preparation process was carried out, and the test results are as follows Figure 1 shown.

[0067] Figure 1 From top to bottom are epoxy oleic acid methyl ester, oleic acid methyl ester-salicylate and the final product acetyl oleic acid methyl ester-salicylate. In the first step of the epoxidation reaction, the infrared curve of epoxy oleic acid methyl ester at 928cm -1 The formation of epoxy bond (COC) proved the successful preparation of epoxy oleic acid methyl ester. Subsequently, the stretching vibration peak of epoxy bond (COC) in the infrared curve of methyl oleate-salicylate disappeared, and the peak at 3493 cm -1 The appearance of the stretching vibration peak of the hydroxyl group (-OH) at 3493 cm -1 The stretching vibration peak of the hydroxyl group (-OH) disappeared, which proved that the acetylation reaction was successful and acetyl oleate methyl ester-salicylate was successfully synthesized.

[0068] Preparation of Softener 2:

[0069] (R 1 =Me, R 3 =OMe, R 4 =-O-COCH 3 , R 2 =R 5 =H)

[0070] (1) 40 g of m-chloroperbenzoic acid was dissolved in 150 mL of dichloromethane and stirred under ice-water bath conditions, and then 100 mL of dichloromethane solution containing 50 g of methyl oleate was added dropwise to the above system, and the above raw materials were first reacted in an ice-water bath for 0.5 h, and then reacted at room temperature for 24 h. After the reaction, the mixture was washed with sodium thiosulfate solution and sodium bicarbonate solution until neutral, and then washed with sodium chloride solution for 3 times, and finally washed with deionized water for 3 times, and then dichloromethane was removed by vacuum distillation at -0.1 MPa and 35° C. to obtain the product epoxy methyl oleate;

[0071] (2) 50 g (0.16 mol) of the product methyl oleate obtained in step (1), 40 g (0.24 mol) of vanillic acid and 0.1 g of tetrabutylammonium chloride are added to a reactor under a nitrogen atmosphere, the above raw materials are mixed and heated to 140° C., and the reaction is continued for 5 hours. After the reaction is completed, the organic phase is washed with deionized water until neutral, and the organic phase is vacuum distilled under -0.1 MPa and 75° C. to remove water to obtain the product methyl oleate-vanillate;

[0072] (3) Add 50 g of the product of step (2) methyl oleate-vanillate, 25 g of acetic anhydride and 5 g of strongly acidic cation exchange resin into a reactor, mix the above raw materials, heat to 85° C., and continue the reaction for 24 hours. After the reaction is completed, first remove the acetic anhydride by vacuum distillation at -0.1 MPa and 120° C., then wash with deionized water to neutrality, and then vacuum distill to remove water at -0.1 MPa and 75° C. to obtain the final product, a bio-based ester environmentally friendly softener methyl acetyl oleate-vanillate.

[0073] Preparation of Softener 3:

[0074] (R 1 =Et, R 3 =R 5 =OMe, R 4 =-O-COCH 3 , R 2 =H)

[0075] (1) 43 g of m-chloroperbenzoic acid was dissolved in 150 mL of dichloromethane and stirred under ice-water bath conditions, and then 100 mL of dichloromethane solution containing 50 g of ethyl oleate was added dropwise to the above system, and the above raw materials were first reacted in an ice-water bath for 0.5 h, and then reacted at room temperature for 24 h. After the reaction, the mixture was washed with sodium thiosulfate solution and sodium bicarbonate solution until neutral, and then washed with sodium chloride solution for 3 times, and finally washed with deionized water for 3 times, and then dichloromethane was removed by vacuum distillation at -0.1 MPa and 35° C. to obtain the product epoxy ethyl oleate;

[0076] (2) 50 g (0.16 mol) of the product ethyl oleate obtained in step (1), 48 g (0.24 mol) of syringic acid and 2.5 g of tetrabutylammonium chloride are added to a reactor under a nitrogen atmosphere, the above raw materials are mixed and heated to 140° C., and the reaction is continued for 5 hours. After the reaction is completed, the organic phase is washed with deionized water until neutral, and the organic phase is then vacuum distilled under -0.1 MPa and 75° C. to remove water to obtain the product ethyl oleate-syringate;

[0077] (3) Add 50 g of the product of step (2) ethyl oleate-syringate, 35 g of acetic anhydride and 7.5 g of a strongly acidic cation exchange resin into a reactor, mix the above raw materials, heat to 85° C., and continue the reaction for 24 hours. After the reaction is completed, first remove the acetic anhydride by vacuum distillation at -0.1 MPa and 120° C., then wash with deionized water to neutrality, and then remove the water by vacuum distillation at -0.1 MPa and 75° C. to obtain the final product, a bio-based ester environmentally friendly softener ethyl acetyl oleate-syringate.

[0078] Preparation of Softener 4:

[0079] (R1 = n-butyl, R 2 =R 5 =-O-COCH 3 , R 3 =R 4 =H)

[0080] (1) 37 g of m-chloroperbenzoic acid was dissolved in 150 mL of dichloromethane and stirred under ice-water bath conditions, and then 100 mL of dichloromethane solution containing 50 g of butyl oleate was added dropwise to the above system, and the above raw materials were first reacted in an ice-water bath for 0.5 h, and then reacted at room temperature for 24 h. After the reaction, the mixture was washed with sodium thiosulfate solution and sodium bicarbonate solution until neutral, and then washed with sodium chloride solution for 3 times, and finally washed with deionized water for 3 times, and then dichloromethane was removed by vacuum distillation at -0.1 MPa and 35° C. to obtain the product epoxy butyl oleate;

[0081] (2) adding 50 g (0.14 mol) of the product butyl oleate obtained in step (1), 32.3 g (0.21 mol) of gentisic acid and 2.5 g of tetrabutylammonium chloride into a reactor under a nitrogen atmosphere, mixing the above raw materials and heating them to 140° C., and continuing the reaction for 5 h. After the reaction is completed, washing with deionized water until neutral, and then vacuum distilling the organic phase at -0.1 MPa and 75° C. to remove water to obtain the product butyl oleate-gentisate;

[0082] (3) Add 50 g of the product of step (2) butyl oleate-gentisate, 35 g of acetic anhydride and 7.5 g of a strongly acidic cation exchange resin into a reactor, mix the above raw materials, heat to 85° C., and continue the reaction for 24 hours. After the reaction is completed, first remove the acetic anhydride by vacuum distillation at -0.1 MPa and 120° C., then wash with deionized water to neutrality, and then vacuum distill to remove water at -0.1 MPa and 75° C. to obtain the final product, a bio-based ester environmentally friendly softener acetyl butyl oleate-gentisate.

[0083] Preparation of Softener 5:

[0084] (R 1 = hexyl, R 3 =R 4 =-O-COCH 3 , R 2 =R 5 =H)

[0085] (1) 37 g of m-chloroperbenzoic acid was dissolved in 150 mL of dichloromethane and stirred under ice-water bath conditions, and then 100 mL of dichloromethane solution containing 50 g of hexyl oleate was added dropwise to the above system, and the above raw materials were first reacted in an ice-water bath for 0.5 h, and then reacted at room temperature for 24 h. After the reaction, the mixture was washed with sodium thiosulfate solution and sodium bicarbonate solution until neutral, and then washed with sodium chloride solution for 3 times, and finally washed with deionized water for 3 times, and then dichloromethane was removed by vacuum distillation at -0.1 MPa and 35° C. to obtain the product epoxy hexyl oleate;

[0086] (2) 50 g (0.13 mol) of the product epoxidized hexyl oleate obtained in step (1), 29.2 g (0.19 mol) of protocatechuic acid and 2 g of tetrabutylammonium chloride were added to a reactor under a nitrogen atmosphere, the raw materials were mixed and heated to 140° C., and the reaction was continued for 5 h. After the reaction was completed, the organic phase was washed with deionized water until neutral, and the organic phase was vacuum distilled under -0.1 MPa and 75° C. to remove water to obtain the product hexyl oleate-protocatechuate;

[0087] (3) Add 50 g of the product of step (2) hexyl oleate-protocatechuate, 35 g of acetic anhydride and 5 g of a strongly acidic cation exchange resin into a reactor, mix the above raw materials, heat to 85° C., and continue the reaction for 24 hours. After the reaction is completed, the acetic anhydride is first removed by vacuum distillation at -0.1 MPa and 120° C., then washed with deionized water until neutral, and then vacuum distilled at -0.1 MPa and 75° C. to remove water to obtain the final product, a bio-based ester environmentally friendly softener hexyl oleate-protocatechuate.

[0088] Preparation of Softener 6:

[0089] (R 1 =Decyl, R 2 =H, R 3 =R 4 =R 5 =-O-COCH 3 )

[0090] (1) Add 0.5 g of formic acid and 0.05 g of acidic ion exchange resin to 50 g of decyl oleate, and drip 35% hydrogen peroxide at 60-75° C. while stirring. The dripping is completed within 4 hours, and then reacted for 1 hour. After the reaction is completed, cool to below 50° C., wash with sodium carbonate solution and deionized water until neutral, and then vacuum distill at -0.1 MPa and 100° C. to remove impurities to obtain the product decyl epoxy oleate;

[0091] (2) adding 50 g (0.11 mol) of the product epoxy oleate obtained in step (1), 30.6 g (0.18 mol) of gallic acid and 2 g of tetrabutylammonium chloride into a reactor under a nitrogen atmosphere, mixing the above raw materials and heating them to 140° C., and continuing the reaction for 5 h. After the reaction is completed, washing with deionized water until neutral, and then vacuum distilling the organic phase at -0.1 MPa and 75° C. to remove water to obtain the product oleate decyl gallate;

[0092] (3) Add 50 g of the product of step (2), 35 g of acetic anhydride and 5 g of a strongly acidic cation exchange resin into a reactor, mix the above raw materials, heat to 85° C., and continue the reaction for 24 hours. After the reaction is completed, first remove the acetic anhydride by vacuum distillation at -0.1 MPa and 120° C., then wash with deionized water to neutrality, and then remove the water by vacuum distillation at -0.1 MPa and 75° C. to obtain the final product, a bio-based ester environmentally friendly softener, acetyl oleic acid decyl ester-gallate.

[0093] Preparation of Softener 7:

[0094] (R 1 =Me, R 3 =R 4 =-O-COCH 3 , R 2 =R 5 =H)

[0095] (1) 80 g of m-chloroperbenzoic acid was dissolved in 150 mL of dichloromethane and stirred under ice-water bath conditions, and then 100 mL of dichloromethane solution containing 50 g of methyl linoleate was added dropwise to the above system, and the above raw materials were first reacted in an ice-water bath for 0.5 h, and then reacted at room temperature for 24 h. After the reaction, the mixture was washed with sodium thiosulfate solution and sodium bicarbonate solution until neutral, and then washed with sodium chloride solution for 3 times, and finally washed with deionized water for 3 times, and then dichloromethane was removed by vacuum distillation at -0.1 MPa and 35° C. to obtain the product methyl epoxylinoleate;

[0096] (2) 50 g (0.16 mol) of the product methyl epoxylinoleate obtained in step (1), 52.36 g (0.34 mol) of protocatechuic acid and 2 g of tetrabutylammonium chloride were added to a reactor under a nitrogen atmosphere, the above raw materials were mixed and heated to 140° C., and the reaction was continued for 5 hours. After the reaction was completed, the organic phase was washed with deionized water until neutral, and the organic phase was vacuum distilled under -0.1 MPa and 75° C. to remove water to obtain the product methyl linoleate-protocatechuate;

[0097] (3) Add 50 g of the product of step (2) methyl linoleate-protocatechuate, 40 g of acetic anhydride and 5 g of strongly acidic cation exchange resin into a reactor, mix the above raw materials, heat to 85° C., and continue the reaction for 24 hours. After the reaction is completed, first remove the acetic anhydride by vacuum distillation at -0.1 MPa and 120° C., then wash with deionized water to neutrality, and then vacuum distill to remove water at -0.1 MPa and 75° C. to obtain the final product, bio-based ester environmentally friendly plasticizer methyl acetyllinoleate-protocatechuate.

[0098] Preparation of Softener 8:

[0099] (R 1 =Me, R 2 =H, R 3 =R 4 =R 5 =-O-COCH 3 )

[0100] (1) 120 g of m-chloroperbenzoic acid was dissolved in 150 mL of dichloromethane and stirred under ice-water bath conditions, and then 100 mL of dichloromethane solution containing 50 g of methyl linolenate was added dropwise to the above system, and the above raw materials were first reacted in an ice-water bath for 0.5 h, and then reacted at room temperature for 24 h. After the reaction, the mixture was washed with sodium thiosulfate solution and sodium bicarbonate solution until neutral, and then washed with sodium chloride solution for 3 times, and finally washed with deionized water for 3 times, and then dichloromethane was removed by vacuum distillation at -0.1 MPa and 35° C. to obtain the product methyl epoxylinolenate;

[0101] (2) 50 g (0.16 mol) of the product methyl epoxylinolenate obtained in step (1), 85 g (0.50 mol) of gallic acid and 1 g of tetrabutylammonium chloride are added to a reactor under a nitrogen atmosphere, the above raw materials are mixed and heated to 140° C., and the reaction is continued for 5 hours. After the reaction is completed, the organic phase is washed with deionized water until neutral, and the organic phase is vacuum distilled under -0.1 MPa and 75° C. to remove water to obtain the product methyl linolenate-gallate;

[0102] (3) Add 50 g of the product of step (2), 45 g of acetic anhydride and 5 g of a strongly acidic cation exchange resin into a reactor, mix the above raw materials, heat to 85° C., and continue the reaction for 24 hours. After the reaction is completed, first remove the acetic anhydride by vacuum distillation at -0.1 MPa and 120° C., then wash with deionized water to neutrality, and then remove the water by vacuum distillation at -0.1 MPa and 75° C. to obtain the final product, a bio-based ester environmentally friendly plasticizer, methyl acetyl linolenate-gallate.

[0103] Preparation of rubber compositions of examples and comparative examples

[0104] The preparation steps are as follows:

[0105] (1) at a temperature of 50-60° C., the raw rubber is plasticized for 10-20 minutes, the roller distance is 3-4 mm, and the thin pass is performed 2-5 times to obtain plasticized rubber;

[0106] (2) adding the above-mentioned plasticized rubber, carbon black, softener, cross-linking agent trimethylolpropane triacrylate (TMPTA) and vulcanizing agent (sulfur (S)) in sequence at a temperature of 70-80° C. and mixing and kneading for 10-15 minutes, with a roller distance of 1-2 mm and thin passing 2-5 times to obtain a mixed rubber;

[0107] (3) The mixed rubber is placed in a mold for compression vulcanization at 170° C. to obtain a rubber material.

[0108] The formulations of the embodiments and comparative examples are shown in Table 1, Table 2, Table 3 and Table 4.

[0109] Table 1 Chloroprene rubber composition formula of Examples 1-4 and Comparative Examples 1-4

[0110]

[0111] Table 2 Formulas of nitrile rubber compositions of Examples 5-8 and Comparative Examples 5-8

[0112]

[0113] Table 3 Formulas of fluororubber compositions of Examples 9-12 and Comparative Examples 9-12

[0114]

[0115] Table 4 Polyurethane rubber composition formula of Examples 13-14 and Comparative Examples 13-14

[0116]

[0117] in,

[0118] Softener A represents benzyl oleate, which can be prepared by the following method: 50 g of oleic acid, 18.8 g of benzyl alcohol, 0.85 g of p-toluenesulfonic acid and 13.5 g of toluene are reacted under a nitrogen atmosphere at 130 °C for 10-12 h. After the reaction is completed, NaHCO 3 solution and deionized water to wash the crude product; finally, the crude product is distilled under reduced pressure to fully remove residual water and solvent in the crude product to obtain benzyl oleate.

[0119] Softener B represents the acetoxy fatty acid methyl ester mentioned in the prior art document CN117986692A (Example 6 in the document).

[0120] Softener C was prepared according to the preparation method of reference softener 1, except that salicylic acid was replaced with benzoic acid to obtain acetyloleic acid methyl ester-benzoate.

[0121] This experiment measures the mechanical properties of the plasticized samples. The material is made into a dumbbell-shaped sample with a test area of ​​2mm thickness and 6mm width. The tensile speed is set to 500mm / min, the experimental temperature is maintained at 23±2℃, and the other test conditions refer to the national standard GB / T 528-2009. At the same time, the remaining film after the tensile properties of the vulcanized film are measured for hardness according to the national standard GB / T6031-2017, and the test equipment is LA / CJ Shore hardness tester.

[0122] The Mooney viscosity of the rubber compound with softener added was measured in the experiment, and the test equipment was the high-speed rail Mooney viscosity meter MV-3000ASU.

[0123] N 2 Thermogravimetric analysis of the softener and the rubber composition was performed with a carrier gas flow rate of 50 mL / min, a test temperature range of 100-550°C, a heating rate of 20°C / min, and a sample mass of 5-10 mg.

[0124] The rubber compositions obtained in Examples 1-12 and Comparative Examples 1-12 were subjected to performance tests. The test results are shown in Table 5.

[0125] Table 5

[0126]

[0127]

[0128] It can be seen from the results of Table 4 that the rubber material obtained by using the softener of the embodiment of the present invention has excellent mechanical properties. Compared with the softener of the comparative example, the tensile strength and elongation at break of the rubber material obtained by the softener of the embodiment of the present invention are increased at the same time, and the hardness and Mooney viscosity are reduced to varying degrees. This is because the fatty acid ester-based softener enters between the molecular chains, only improves the mobility of the molecular chains, does not destroy the chain segments between the macromolecules, and maintains the good tensile strength of the composite material. The more polar groups present in the fatty acid ester-based softener of the present invention enhance the compatibility between the softener and the rubber matrix, effectively reduce the interaction force between the rubber molecular chains, and make the rubber molecular chains easier to slide, thereby enhancing the mechanical properties of the rubber material, reducing the hardness and Mooney viscosity, and improving the processing properties of the rubber material.

[0129] In addition, thermogravimetric analysis was performed on five softeners: methyl oleate, softener A (benzyl oleate), softener B (acetoxy fatty acid methyl ester), softener C (methyl acetyl oleate-benzoate), and softener 1 (methyl acetyl oleate-salicylate). The results are as follows: Figure 2 As shown in Table 6, when the mass loss is 50%, the degradation temperature of acetyl oleate-salicylate is higher than that of other softeners.

[0130] Table 6

[0131] Softener <![CDATA[T d-50％ ]]> Softener 1 376 Softener 7 379 Softener 8 383 Methyl oleate 262 Softener A 274 Softener B 272 Softener C 364

[0132] Table T d-50％ It indicates the thermal degradation temperature corresponding to 50% mass loss of the softener.

[0133] This shows that the synthesized softener 1 has higher thermal stability, because the fatty acid ester only contains a long fatty chain structure and has a small molecular weight, so its thermal stability is the worst; oleic acid benzyl alcohol ester contains a benzene ring structure, an ester group and a long chain structure, so its thermal stability is higher; acetoxy fatty acid methyl ester only contains a long fatty chain structure and an ester branch and has a small molecular weight, so its thermal stability is poor; acetyl oleic acid methyl ester-benzoate contains a benzene ring, two ester groups, a long fatty chain and an ester branch, and its thermal stability is higher; acetyl fatty acid ester-salicylate contains a benzene ring structure, a long fatty chain structure, multiple ester groups and a short ester branch structure and its molecular weight is higher than other softeners, so its thermal stability is the best.

[0134] Furthermore, the rubber compositions obtained in Examples 1-14 and Comparative Examples 1-12 were subjected to thermogravimetric analysis. The results are shown in Table 7.

[0135] Table 7

[0136]

[0137]

[0138] Table T d-50％ It indicates the thermal degradation temperature corresponding to 50% mass loss of the rubber composition.

[0139] From the results in Table 6, it can be seen that the degradation temperature corresponding to the mass loss of 50% of the rubber material obtained by using the softener of the present invention is higher than that of the rubber material obtained by the comparative sample. The addition of the softener of the present invention has a significant effect on the degradation behavior of the rubber material, and its thermal degradation stability is significantly improved. This is because the softener enters between the molecular chains, only improving the mobility of the molecular chains, and does not destroy the chain segments between the macromolecules. The more polar groups present in the softener prepared by the present invention enhance the compatibility between the softener and the rubber matrix, so that the softener is evenly dispersed in the rubber material, thereby enhancing the thermal degradation temperature of the rubber material.

[0140] The embodiments provided above are not intended to limit the scope of the present invention, and the steps described are not intended to limit the execution order thereof. Those skilled in the art may make obvious improvements to the present invention in combination with existing common knowledge, which also fall within the scope of protection defined by the claims of the present invention.

Claims

1. A rubber composition, characterized in that: The raw materials include 80-120 parts by weight of raw rubber, 20-50 parts by weight of filler, 1-30 parts by weight of bio-based ester softener, and 1-5 parts by weight of functional additives; The structure of the bio-based ester softener is shown in formula (A1), (A2), or (A3): In the formula, R1 is C 1-10 alkyl; n1 is the number of -CH2- groups on the aliphatic chain, which is 1, 2, 3, 4, 5, 6, 7 or 8; n2 is the number of substituents R2 on the benzene ring, which is 1, 2, 3 or 4; Each R2 is independently selected from -O-C1-4 alkyl, -OCO-C 1-4 alkyl; n3 is the number of -CH2- groups on the aliphatic chain, which is 1, 2, 3, 4, 5, 6, 7 or 8; n4 is the number of -CH2- groups on the aliphatic chain, which is 1, 2, 3, 4, 5, 6, 7 or 8; n5 is the number of -CH2- on the aliphatic chain, which is 1, 2, 3, 4, 5, 6, 7 or 8.

2. The rubber composition according to claim 1, characterized in that The structure of the bio-based ester softener is specifically as follows: R1 is methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, pentyl, hexyl, heptyl, octyl, decyl; R2, R3, R4, and R5 are independently selected from methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, tert-butoxy, acetoxy, propionyloxy, and butyryloxy; and the rest are hydrogen.

3. The rubber composition according to claim 1, characterized in that The structure of the bio-based ester softener is specifically as follows: R1 is C 1-10 alkyl; At least one of R2, R3, R4 and R5 is selected from acetoxy, and the others are hydrogen or methoxy.

4. The rubber composition according to any one of claims 1 to 3, characterized in that The preparation method of the bio-based ester softener is as follows: first, fatty acid ester and catalyst 1 are used as raw materials to prepare epoxy fatty acid ester through epoxidation reaction; then, epoxy fatty acid ester, natural organic acid and ring-opening agent are subjected to ring-opening reaction to prepare fatty acid ester-organic acid ester; finally, fatty acid ester-organic acid ester, acetic anhydride and catalyst 2 are subjected to acetylation reaction to obtain the bio-based ester softener.

5. The rubber composition according to claim 4, characterized in that The fatty acid ester is at least one of methyl oleate, ethyl oleate, butyl oleate, hexyl oleate, octyl oleate, decyl oleate, methyl linoleate, ethyl linoleate, butyl linoleate, hexyl linoleate, octyl linoleate, decyl linoleate, methyl linoleate, ethyl linoleate, butyl linoleate, hexyl linoleate, octyl linoleate and decyl linoleate; the natural organic acid is at least one of salicylic acid, vanillic acid, syringic acid, gentisic acid, protocatechuic acid and gallic acid; the catalyst 1 is any one of meta-chloroperbenzoic acid and hydrogen peroxide; the ring-opening agent is any one of tetrabutylammonium chloride and tetrabutylammonium bromide; the catalyst 2 is any one of an acidic cation exchange resin and concentrated sulfuric acid.

6. The rubber composition according to claim 4, characterized in that In the epoxidation reaction, the molar ratio of fatty acid ester to catalyst 1 is 1:1.2-3.

2.

7. The rubber composition according to claim 4, characterized in that In the ring-opening reaction, the molar ratio of the epoxy fatty acid ester to the natural organic acid is 1:1.4-4.5; the amount of the ring-opening agent added is 0.1wt%-5wt% of the mass of the epoxy fatty acid ester; In the acetylation reaction, the amount of acetic anhydride added is 50%-90% of the fatty acid ester-organic acid ester; the amount of catalyst 2 added is 5wt%-15wt% of the fatty acid ester-organic acid ester.

8. The rubber composition according to any one of claims 1 to 7, characterized in that: The raw rubber is a polar rubber, which is one or more of nitrile rubber, chloroprene rubber, fluororubber, polyurethane rubber, ethylene-acrylate rubber, silicone rubber, chlorosulfonated polyethylene rubber, and polyether rubber.

9. A method for preparing the rubber composition according to any one of claims 1 to 8, characterized in that: The steps include: (1) Plasticizing the raw rubber for 10-20 minutes; (2) adding fillers, bio-based softeners, and functional additives according to the weight proportions in claim 1 and blending and kneading for 10-15 minutes to obtain a rubber compound; (3) The rubber mixture is placed in a mold for compression vulcanization to obtain a rubber composition.

10. Use of the rubber composition according to any one of claims 1 to 8 in tires, seals, wires and cables, conveyor belts, rubber products and petroleum industries.

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