High-strength thermoplastic rubber and preparation method thereof

Abstract

The invention relates to the technical field of thermoplastic rubber, and discloses high-strength thermoplastic rubber and a preparation method thereof. The preparation method comprises the following steps: reacting 2, 2-diphenylacetic acid with epoxy natural rubber, then reacting with carboxymethyl cellulose to obtain natural rubber grafted cellulose, and finally mixing the natural rubber grafted cellulose with SEBS, polyethylene wax and other assistants, calcium carbonate and other fillers to obtain the high-strength thermoplastic rubber. Cellulose of the grafted phenyl natural rubber has good compatibility with SEBS, the cellulose has a better reinforcing effect on SEBS thermoplastic rubber, meanwhile, the introduced natural rubber molecular chain is high in flexibility, the elongation at break of the thermoplastic rubber can be improved, and the rubber has excellent toughness while keeping high strength and high hardness.

Description

Technical Field

[0001] The present invention relates to the technical field of thermoplastic rubber, in particular to a high-strength thermoplastic rubber and a preparation method thereof. Background Art

[0002] SEBS (hydrogenated styrene-butadiene-styrene block copolymer) is a high-performance thermoplastic rubber elastomer material with excellent toughness and elasticity, strong plasticity, high insulation properties, and excellent UV and aging resistance. It is widely used in foam materials, wire and cable materials, and medical devices. However, SEBS rubber has low rigidity and mechanical strength, which limits its practical application.

[0003] Cellulose has high strength, is readily available, and is environmentally friendly and pollution-free, making it an important material for the reinforcement and modification of plastics and rubber. A master's thesis, "Preparation and Performance Research of Self-Healing Ultrasonic Phantom Materials," describes a SEBS / EC biphasic interpenetrating cross-linked oil gel ultrasound phantom material prepared using SEBS as a matrix, diethylene glycol ethyl ether as a compatibilizer, and ethyl cellulose (EC) as a scatterer. The material exhibits excellent self-healing and mechanical properties. However, cellulose has a poor elongation at break, and its addition to SEBS compromises its toughness. Summary of the Invention

[0004] (1) Technical Problems Solved: In view of the deficiencies in the prior art, the present invention provides a thermoplastic rubber with high mechanical strength and a preparation method thereof.

[0005] (II) Technical Solution: A method for preparing high-strength thermoplastic rubber:

[0006] (1) Toluene, epoxy natural rubber, and 2,2-diphenylacetic acid were added to a reaction flask, stirred for reaction, and then the solution was poured into ethanol for precipitation. After filtering, the precipitate was washed with ethanol and dried to obtain phenyl natural rubber. The preparation reaction formula is:

[0007]

[0008] (2) Add dimethyl sulfoxide, carboxymethyl cellulose, 4-dimethylaminopyridine, and N,N-dicyclohexylcarbodiimide to a reaction flask, stir to activate, then add phenyl natural rubber, stir to carry out esterification reaction, pour the solution into water for precipitation, filter, wash the precipitate with ethanol, and dry to obtain natural rubber grafted cellulose.

[0009] (3) The hydrogenated styrene-butadiene-styrene block copolymer (SEBS) is plasticized in an internal mixer, and then natural rubber grafted cellulose, additives, and fillers are added, mixed, and then discharged to obtain a high-strength thermoplastic rubber.

[0010] Preferably, the mass ratio of (1) the epoxy natural rubber and 2,2-diphenylacetic acid is 100:(60-150).

[0011] Preferably, the temperature of the reaction in (1) is 100-110℃, and the reaction time is 12-18h.

[0012] Preferably, the mass ratio of (2) carboxymethyl cellulose, 4-dimethylaminopyridine, N,N-dicyclohexyl carbodiimide, and phenyl natural rubber is 100:(0.5-1.2):(8-20):(15-40).

[0013] Preferably, the temperature of the stirring activation in (2) is 20-35℃, and the time is 2-3h.

[0014] Preferably, the temperature of the stirring reaction in (2) is 20-50℃, and the time is 24-36h.

[0015] Preferably, the temperature of the plasticizing in (3) is 190-200℃, and the time is 8-15min.

[0016] Preferably, the mixing time in (3) is 3-5min.

[0017] Preferably, the mass ratio of (3) hydrogenated styrene-butadiene-styrene block copolymer SEBS, natural rubber grafted cellulose, auxiliary agent, and filler is 100:(30-70):(2-6):(15-30).

[0018] Preferably, the auxiliary agent in (3) includes white oil, paraffin oil, or polyethylene wax.

[0019] Preferably, the filler in (3) includes calcium carbonate powder or talc powder.

[0020] (Three) beneficial technical effects:

[0021] The carboxyl group of 2,2-diphenylacetic acid and the epoxy group of the epoxy natural rubber are subjected to ring-opening reaction to obtain natural rubber containing a diphenyl structure, the hydroxyl group generated by ring-opening is subjected to esterification reaction with carboxymethyl cellulose to obtain natural rubber grafted cellulose, and finally SEBS, filler, and the like are mixed to obtain high-strength thermoplastic rubber.

[0022] The natural rubber and the diphenyl structure are grafted into the cellulose molecular chain, the polyisoprene molecular chain of the natural rubber is similar to the hydrogenated butadiene molecular chain in the SEBS, and the diphenyl structure has strong π-π bond interaction with the polystyrene segment in the SEBS, so that the cellulose grafted with the phenyl natural rubber has good compatibility with the SEBS, the cellulose has high rigidity and strength, has a better reinforcing effect on the SEBS thermoplastic rubber, and the introduced natural rubber molecular chain has high flexibility, which is beneficial to improve the elongation at break of the thermoplastic rubber, so that the rubber has high strength and high hardness, and has excellent toughness. DETAILED DESCRIPTION

[0023] In order to make the technical scheme of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and completely below. It should be noted that the following embodiments are only used to better understand the technical scheme of the present application, and should not be understood as a limitation of the present application.

[0024] The SEBS is a hydrogenated styrene-butadiene-styrene block copolymer with a model number of G1645M, and is from Dongguan Yuhong Plastic Co., Ltd. The carboxymethyl cellulose has a content of 99.5%, and is from Guangzhou Chunzheng Chemical Co., Ltd. The epoxy natural rubber has a model number of ENR50, and is from Dongguan Donglin Polymer Material Co., Ltd.

[0025] Example 1

[0026] (1) 700 mL of toluene, 40 g of epoxy natural rubber and 24 g of 2,2-diphenylacetic acid were added to a reaction bottle, heated to 110 DEG C, stirred and condensed refluxed for 12 h, and then the solution was poured into ethanol for precipitation. After filtration, the precipitate was washed with ethanol and dried to obtain a phenyl natural rubber.

[0027] (2) 3 L of dimethyl sulfoxide, 200 g of carboxymethyl cellulose, 1 g of 4-dimethylaminopyridine and 16 g of N,N-dicyclohexyl carbodiimide were added to a reaction bottle, stirred and activated at 25 DEG C for 2 h, 30 g of phenyl natural rubber was added, and esterification reaction was carried out at 40 DEG C for 24 h. The solution was poured into water for precipitation, and after filtration, the precipitate was washed with ethanol and dried to obtain a natural rubber grafted cellulose.

[0028] (3) 1 kg of hydrogenated styrene-butadiene-styrene block copolymer SEBS was plasticized in a mixing mill at 190 DEG C for 12 min, then 300 g of natural rubber grafted cellulose, 60 g of white oil and 300 g of calcium carbonate powder were added, and mixed for 5 min. The material was discharged to obtain a high-strength thermoplastic rubber.

[0029] Example 2

[0030] (1) Into a reaction flask, 800 mL of toluene, 40 g of epoxidized natural rubber, 40 g of 2,2-diphenylacetic acid were added, heated to 100°C, stirred and condensed reflux reaction for 18 h, the solution was poured into ethanol for precipitation, the precipitate was washed with ethanol after filtration, and dried to obtain phenyl natural rubber.

[0031] (2) Into a reaction flask, 3 L of dimethyl sulfoxide, 200 g of carboxymethyl cellulose, 1.8 g of 4-dimethylaminopyridine, 25 g of N,N-dicyclohexyl carbodiimide were added, stirred and activated at 20°C for 3 h, 60 g of phenyl natural rubber was added, and esterification reaction was stirred at 20°C for 36 h, the solution was poured into water for precipitation, the precipitate was washed with ethanol after filtration, and dried to obtain natural rubber grafted cellulose.

[0032] (3) 1 kg of hydrogenated styrene-butadiene-styrene block copolymer SEBS was plasticized in an internal mixer at 200°C for 8 min, then 500 g of natural rubber grafted cellulose, 20 g of polyethylene wax, 250 g of calcium carbonate powder were added, mixed for 3 min, and discharged to obtain high-strength thermoplastic rubber.

[0033] Example 3

[0034] (1) Into a reaction flask, 800 mL of toluene, 40 g of epoxidized natural rubber, 40 g of 2,2-diphenylacetic acid were added, heated to 100°C, stirred and condensed reflux reaction for 18 h, the solution was poured into ethanol for precipitation, the precipitate was washed with ethanol after filtration, and dried to obtain phenyl natural rubber.

[0035] (2) Into a reaction flask, 3 L of dimethyl sulfoxide, 200 g of carboxymethyl cellulose, 1.8 g of 4-dimethylaminopyridine, 25 g of N,N-dicyclohexyl carbodiimide were added, stirred and activated at 20°C for 3 h, 60 g of phenyl natural rubber was added, and esterification reaction was stirred at 20°C for 36 h, the solution was poured into water for precipitation, the precipitate was washed with ethanol after filtration, and dried to obtain natural rubber grafted cellulose.

[0036] (3) 1 kg of hydrogenated styrene-butadiene-styrene block copolymer SEBS was plasticized in an internal mixer at 200°C for 8 min, then 500 g of natural rubber grafted cellulose, 20 g of polyethylene wax, 250 g of calcium carbonate powder were added, mixed for 3 min, and discharged to obtain high-strength thermoplastic rubber.

[0037] Comparative Example 1

[0038] (1) 1 kg of hydrogenated styrene-butadiene-styrene block copolymer SEBS was plasticized in an internal mixer at 200°C for 8 min, then 500 g of natural rubber grafted cellulose, 20 g of polyethylene wax, 250 g of calcium carbonate powder were added, mixed for 3 min, and discharged to obtain high-strength thermoplastic rubber.

[0039] Comparative Example 2

[0040] (1) A reaction flask was charged with 700 mL of toluene, 40 g of epoxidized natural rubber, 24 g of benzoic acid, heated to 110°C, stirred and refluxed with condensation for 12 h, the solution was poured into ethanol for precipitation, the precipitate was washed with ethanol after filtration, and dried to obtain a phenyl natural rubber.

[0041] (2) A reaction flask was charged with 3 L of dimethyl sulfoxide, 200 g of carboxymethyl cellulose, 1 g of 4-dimethylaminopyridine, 16 g of N,N-dicyclohexyl carbodiimide, stirred and activated for 2 h at 25°C, 30 g of phenyl natural rubber was added, stirred and reacted for 24 h at 40°C, the solution was poured into water for precipitation, the precipitate was washed with ethanol after filtration, and dried to obtain a natural rubber grafted cellulose.

[0042] (3) 1 kg of hydrogenated styrene-butadiene-styrene block copolymer SEBS was plasticized in an internal mixer at 190°C for 12 min, then 300 g of natural rubber grafted cellulose, 60 g of white oil, and 300 g of calcium carbonate powder were mixed for 5 min, and discharged to obtain a thermoplastic rubber.

[0043] Comparative Example 3

[0044] (1) A reaction flask was charged with 3 L of dimethyl sulfoxide, 200 g of carboxymethyl cellulose, 30 g of epoxidized natural rubber, heated to 110°C, stirred and reacted for 12 h, the solution was poured into ethanol for precipitation, the precipitate was washed with ethanol after filtration, and dried to obtain a natural rubber grafted cellulose.

[0045] (2) 1 kg of hydrogenated styrene-butadiene-styrene block copolymer SEBS was plasticized in an internal mixer at 190°C for 12 min, then 300 g of natural rubber grafted cellulose, 60 g of white oil, and 300 g of calcium carbonate powder were mixed for 5 min, and discharged to obtain a thermoplastic rubber.

[0046] Comparative Example 4

[0047] (1) 200 g of carboxymethyl cellulose and 30 g of phenyl natural rubber were stirred and blended to obtain a natural rubber-cellulose mixture.

[0048] (2) 1 kg of hydrogenated styrene-butadiene-styrene block copolymer SEBS was plasticized in an internal mixer at 190°C for 12 min, then 300 g of natural rubber-cellulose mixture, 60 g of white oil, and 300 g of calcium carbonate powder were mixed for 5 min, and discharged to obtain a thermoplastic rubber.

[0049] The thermoplastic rubber was hot-pressed in a hot press at 200 ℃ for 6 min at a pressure of 3 MPa to form a sample. The tensile properties were tested according to the GB / T 528-2009 standard. The hardness was tested according to the GB / T 531.1-2008 standard. The test results are shown in Table 1.

[0050] Table 1 Properties of thermoplastic rubber

[0051]

[0052] As can be seen from Table 1, the tensile strength, elongation at break and hardness of the thermoplastic rubber obtained by mixing carboxymethyl cellulose and SEBS in Comparative Example 1 are low, mainly because the compatibility of cellulose and SEBS is poor, and the cellulose forms phase separation in the SEBS rubber matrix, which is not conducive to improving the mechanical properties of the rubber. In Examples 1-3, the hydroxyl groups of phenyl natural rubber are esterified with carboxymethyl cellulose to graft natural rubber to the cellulose molecular chain, and then mixed with SEBS, and the tensile strength, elongation at break and hardness of the obtained thermoplastic rubber are significantly improved, the strength and toughness are improved, mainly because the polyisoprene molecular chain of phenyl natural rubber is similar to the hydrogenated butadiene molecular chain in SEBS, and contains a diphenyl structure which has a strong π-π bond interaction with the polystyrene segment in SEBS, so that the cellulose grafted with phenyl natural rubber has good compatibility with SEBS. The cellulose is rigid and has high strength, and has a better reinforcing effect on SEBS thermoplastic rubber. The introduced natural rubber molecular chain has high flexibility, which is conducive to improving the elongation at break of the thermoplastic rubber, so that the rubber has high strength and hardness while having excellent toughness.

[0053] In Comparative Example 2, conventional benzoic acid is reacted with natural rubber to obtain phenyl and grafted cellulose which does not contain a diphenyl structure, and the π-π bond interaction with the polystyrene segment in SEBS is low, resulting in lower compatibility of cellulose with SEBS than Example 1, poor reinforcing effect, and lower tensile properties and hardness of the thermoplastic rubber than Example 1.

[0054] In Comparative Example 3, the carboxyl groups of carboxymethyl cellulose are directly reacted with the epoxy groups of epoxy natural rubber to obtain grafted cellulose which does not contain a benzene ring structure, resulting in poor compatibility of cellulose with SEBS, low reinforcing effect, and poor tensile properties and hardness of the thermoplastic rubber.

[0055] In Comparative Example 4, a mixture of carboxymethyl cellulose and epoxy natural rubber is blended with SEBS, and the cellulose is not grafted with natural rubber, and no polyisoprene molecular chain and benzene ring structure are added, so the compatibility with SEBS is very poor, and the tensile properties and hardness of the thermoplastic rubber are poor.

[0056] It is to be understood that the present application is described by way of example only, and that modifications or alterations can be made to the features and embodiments described without departing from the spirit and scope of the application as it is known to those skilled in the art.

Claims

1. A method for preparing high-strength thermoplastic rubber, characterized in that: The preparation method comprises: (1) Add dimethyl sulfoxide, carboxymethyl cellulose, 4-dimethylaminopyridine, and N,N-dicyclohexylcarbodiimide to a reaction flask, stir to activate, then add phenyl natural rubber, stir to react, pour the solution into water for precipitation, filter, wash the precipitate, and dry to obtain natural rubber grafted cellulose; (2) The hydrogenated styrene-butadiene-styrene block copolymer (SEBS) is plasticized in an internal mixer, and then natural rubber grafted cellulose, additives, and fillers are added, mixed, and then discharged to obtain a high-strength thermoplastic rubber.

2. The method for preparing high-strength thermoplastic rubber according to claim 1, characterized in that: The mass ratio of carboxymethyl cellulose, 4-dimethylaminopyridine, N,N-dicyclohexylcarbodiimide and phenyl natural rubber in (1) is 100:(0.5-1.2):(8-20):(15-40).

3. The method for preparing high-strength thermoplastic rubber according to claim 1, characterized in that: The temperature during the stirring activation in (1) is 20-35° C. and the time is 2-3 hours.

4. The method for preparing high-strength thermoplastic rubber according to claim 1, characterized in that: The stirring reaction in (1) is carried out at a temperature of 20-50° C. and for a time of 24-36 hours.

5. The method for preparing high-strength thermoplastic rubber according to claim 1, characterized in that: The temperature during the plasticating in (2) is 190-200° C., and the time is 8-15 minutes; the mixing time is 3-5 minutes.

6. The method for preparing high-strength thermoplastic rubber according to claim 1, characterized in that: The mass ratio of hydrogenated styrene-butadiene-styrene block copolymer SEBS, natural rubber grafted cellulose, additives and fillers in (2) is 100:(30-70):(2-6):(15-30).

7. The method for preparing high-strength thermoplastic rubber according to claim 6, characterized in that: The auxiliary agent is white oil, paraffin oil or polyethylene wax.

8. The method for preparing high-strength thermoplastic rubber according to claim 6, characterized in that: The filler is calcium carbonate powder or talc powder.

9. The method for preparing high-strength thermoplastic rubber according to claim 1, characterized in that: The preparation method of the phenyl natural rubber comprises: adding toluene, epoxy natural rubber and 2,2-diphenylacetic acid in a mass ratio of 100:(60-150) into a reaction bottle, heating to 100-110° C., condensing and refluxing for 12-18 hours, pouring the solution into ethanol for precipitation, filtering and washing the precipitate, and drying to obtain the phenyl natural rubber.

10. A high-strength thermoplastic rubber obtained by the preparation method according to any one of claims 1 to 9.

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