Polycarboxylic acid type dispersing agent as well as preparation method and application thereof

Abstract

The invention relates to the technical field of dispersing agents, and particularly discloses a polycarboxylic acid type dispersing agent as well as a preparation method and application thereof. The preparation method comprises the following steps: polymerizing itaconic acid, 2-acrylamide-2-methylpropanesulfonic acid, glycidyl methacrylate, methyl styrene, gamma-methacryloxypropyltrimethoxysilane, the modified hybrid compound, vinyl 2-mercaptopropionate and allyl polyoxyethylene ether to obtain a polycarboxylic acid type dispersing agent; the dispersing agent has excellent dispersing performance and heat resistance, the dispersing agent is not prone to losing efficacy in the high-temperature vulcanization process in the rubber processing process, and when filler and rubber are mixed, the dispersing agent is firmly adsorbed on the surfaces of filler particles through multiple acting forces, so that the dispersing agent is not prone to losing efficacy, and the service life of the dispersing agent is prolonged. The dispersing performance of the filler and the interface bonding force with rubber are improved, so that the filler is uniformly distributed in the rubber, a stable dispersion system is formed, the mechanical property of vulcanized rubber is improved, and the processing fluidity is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of dispersants, in particular to a polycarboxylic acid type dispersant and a preparation method and application thereof. BACKGROUND

[0002] Dispersants play a crucial role in the rubber industry. Fillers such as carbon black and white carbon black are added to rubber materials to improve mechanical properties. However, due to their extremely high specific surface area and surface energy, filler particles tend to agglomerate, forming difficult-to-break agglomerates, which leads to uneven dispersion in the rubber matrix. Dispersants can improve the dispersibility of fillers and improve the mechanical properties and processing performance of rubber products. Polycarboxylate dispersants have attracted widespread attention due to their good dispersing effect and environmental protection properties, and are increasingly widely used in the rubber industry. However, existing polycarboxylic acid type dispersants still have some deficiencies when applied in the rubber industry.

[0003] Chinese patent application CN114933669A discloses a preparation method of a polycarboxylic acid sodium salt dispersant with adjustable dispersion force for rubber. By introducing a styrene segment into the dispersant, the composition and structure of the dispersant are optimized to improve the glass transition temperature of the dispersant. However, the effective adsorption sites for polar fillers such as carbon black and white carbon black are reduced, the dispersion stability at high temperatures is insufficient, and the processing fluidity is reduced. Chinese patent application CN118184866A discloses a preparation method of a polycarboxylic acid sodium salt dispersant with adjustable dispersion force for rubber. Monomers undergo polymerization and saponification reactions, and amide-type adjusters are used for ring-opening and nucleophilic substitution reactions to consolidate the dispersion force and improve the glass transition temperature, which can meet the requirements of different materials and use environments. However, the reaction system is complex, the conditions are harsh, industrial production is difficult, the environmental friendliness of reagents such as phenol is poor, and the dispersion stability is poor, and the fillers are prone to secondary agglomeration.

[0004] Therefore, there is an urgent need to develop a polycarboxylic acid type dispersant with environmental friendliness, high dispersibility, and high temperature resistance, which has important industrial application value. SUMMARY

[0005] (I)Technical problems to be solved In view of the deficiencies of the prior art, the present application provides a polycarboxylic acid type dispersant and a preparation method and application thereof, which solves the problems of general high temperature resistance and dispersibility of polycarboxylic acid type dispersants.

[0006] (II)Technical solutions In order to achieve the above-mentioned purpose, a preparation method of a polycarboxylic acid type dispersant is disclosed, comprising the following steps: Step one, disperse the nanocellulose into N,N-dimethylformamide, after uniform dispersion, heat, add 4-dimethylaminopyridine, stir and mix, then add alkenyl succinic anhydride, stir and mix, react, after the reaction is completed, wash with anhydrous ethanol and deionized water, and dry at 60°C under vacuum for 24h to obtain modified cellulose; Step two, ultrasonic dispersion of nanosilica into the mixed solution, after uniform mixing, add sodium dodecyl benzene sulfonate solution, stir and mix, add chitosan dissolved in acetic acid solution, stir and mix for 4h, add glutaraldehyde, stir and react for 4-6h, rotary evaporation to obtain chitosan@silica; Step three, mix the acetic acid solution and chitosan@silica uniformly, then add modified cellulose, 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide, N-hydroxysuccinimide, stir and mix, react, after the reaction is completed, centrifuge, dialysis with deionized water, freeze-drying to obtain modified hybrid composite; Step four, mix the mixed solvent, itaconic acid, 2-acrylamide-2-methylpropane sulfonic acid, glycidyl methacrylate, methyl styrene, gamma-methacryloyloxypropyl trimethoxysilane, modified hybrid composite, 2-mercapto propionic acid vinyl ester, allyl polyoxyethylene ether, heat under nitrogen atmosphere, add initiator and chain transfer agent, stir and mix, react, after the reaction is completed, cool, adjust pH to 6-7 using 30wt% sodium hydroxide aqueous solution, remove the solvent by distillation under reduced pressure to obtain polycarboxylic acid type dispersant.

[0007] As a further scheme of the application: the addition ratio of nanocellulose, N,N-dimethylformamide, 4-dimethylaminopyridine and alkenyl succinic anhydride in step one is 10g:90-120mL:1-2g:28-35g.

[0008] As a further scheme of the application: the reaction temperature in step one is 80-90°C, and the reaction time is 4-6h.

[0009] As a further scheme of the application: the alkenyl succinic anhydride in step one is any one of alkyl long-chain alkenyl succinic anhydride, including hexadecenyl succinic anhydride, tetradecenyl succinic anhydride, dodecenyl succinic anhydride.

[0010] As a further scheme of the application: the addition ratio of nanosilica, mixed solution, sodium dodecyl benzene sulfonate solution, chitosan and glutaraldehyde in step two is 1g:240-300mL:45-55mL:0.8-1.2g:12-15mL.

[0011] As a further scheme of the application: the reaction temperature in step two is 30-40°C.

[0012] As a further scheme of the present application: the acetic acid solution in step two is 1wt% acetic acid solution.

[0013] As a further scheme of the present application: the concentration of the sodium dodecyl benzene sulfonate solution in step two is 0.025mol / L.

[0014] As a further scheme of the present application: the mixed solution in step two is a buffer solution of acetic acid and sodium acetate, and the pH is 3.5.

[0015] As a further scheme of the present application: the addition ratio of the acetic acid solution, chitosan@silica, modified cellulose, 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide, and N-hydroxysuccinimide in step three is 180-210mL:10g:7-12g:1.5-2.5g:0.3-0.8g.

[0016] As a further scheme of the present application: the reaction temperature in step three is 35-45℃, and the reaction time is 8-12h.

[0017] As a further scheme of the present application: the acetic acid solution in step three is 1wt% acetic acid solution.

[0018] As a further scheme of the present application: the addition ratio of the mixed solvent, itaconic acid, 2-acrylamide-2-methylpropanesulfonic acid, glycidyl methacrylate, methyl styrene, γ-methacryloyloxypropyl trimethoxysilane, modified hybrid composite, 2-mercapto propionic acid vinyl ester, allyl polyoxyethylene ether, initiator, and chain transfer agent in step four is 300-350mL:15-25g:10-20g:5-15g:5-10mL:3-8g:2-6g:1-3g:20-30g:0.5-2g:0.1-0.3g.

[0019] As a further scheme of the present application: the reaction temperature in step four is 70-80℃, and the reaction time is 4-6h.

[0020] As a further scheme of the present application: the initiator in step four is azobisisobutyronitrile.

[0021] As a further scheme of the present application: the chain transfer agent in step four is dodecanethiol.

[0022] As a further scheme of the present application: the mixed solvent in step four is composed of isopropyl alcohol and deionized water in a volume ratio of 4:1.

[0023] As a further scheme of the present application: a polycarboxylic acid dispersant prepared by the preparation method of the polycarboxylic acid dispersant.

[0024] As a further scheme of the present application: the polycarboxylic dispersant is applied in rubber processing.

[0025] (Three) beneficial technical effects Compared with the prior art, the beneficial effects of the present application are: (1) In the present application, the surface of nanocellulose is rich in hydroxyl groups, which undergoes ring-opening reaction with alkyl long-chain alkenyl succinic anhydride to introduce alkenyl and hydrophobic long carbon chain on the cellulose skeleton. The introduction of long-chain alkenyl enhances the solubility of modified cellulose and the compatibility with hydrophobic systems such as rubber. Sodium dodecylbenzenesulfonate as an anionic surfactant is adsorbed on the surface of nanosilica, making it hydrophobic and negatively charged, and the amino groups on chitosan are adsorbed on the surface of nanosilica through electrostatic interaction. Nanosilica is coated with a layer of chitosan polymer, which can better adapt to the surface of fillers as a dispersant component, increase the contact area and adsorption force, and introduce a large number of active groups. After cross-linking with glutaraldehyde, a three-dimensional network shell is formed, further improving the compatibility and avoiding the phase separation problem caused by rigid inorganic particles, making the final product more uniform and stable. The carboxyl groups on the modified cellulose and the amino groups on the chitosan@silica undergo amide reaction to obtain a modified hybrid composite, forming a three-dimensional hybrid network. Nanocellulose and nanosilica themselves have extremely high thermal stability and rigidity, and are integrated into the polymer system through covalent bonds as "skeleton", effectively blocking heat conduction and inhibiting molecular chain thermal degradation, greatly enhancing the rigidity and thermal stability of the entire dispersant molecule, making it difficult for the molecular chain to break, curl or entangle at high temperature, and still maintaining stable dispersion effect in high temperature environment, thereby maintaining the effectiveness of steric hindrance.

[0026] (2) In the application, itaconic acid, 2-acrylamide-2-methylpropanesulfonic acid, glycidyl methacrylate, methylstyrene, gamma-methacryloxypropyltrimethoxysilane, modified hybrid compound, 2-mercapto propionic acid vinyl ester, allyl polyoxyethylene ether are copolymerized by free radicals to construct an amphiphilic polycarboxylic acid main chain to obtain a polycarboxylic acid type dispersant. Part of the bio-based raw materials are used, which meets the green chemistry trend and is green and environmentally friendly. The nano-composite is anchored on the polymer main chain through covalent bonds, which combines the triple action mechanisms of electrostatic repulsion, steric hindrance and anchoring adsorption, and has excellent dispersion effect on inorganic fillers, effectively preventing sedimentation and agglomeration. Itaconic acid and 2-acrylamide-2-methylpropanesulfonic acid can provide strong hydration and electrostatic repulsion, and have good dispersion stability. The 2-acrylamide-2-methylpropanesulfonic acid introduced in the molecular chain contains strong polar sulfonic acid group and tert-butyl structure, the sulfonic acid group forms a conjugated stable system with the main chain, and the steric hindrance of the tert-butyl group inhibits the thermal motion of the molecular chain, so that the thermal decomposition temperature of the main chain is increased. Allyl polyoxyethylene ether provides long-chain polyether side chains to form a thick hydration layer around the rubber filler, which produces steric hindrance and effectively prevents filler particle agglomeration.

[0027] (3) In the application, the benzene ring structure in the introduced methylstyrene is compatible with the hydrophobic segment of the rubber, which improves the compatibility. The epoxy group in the glycidyl methacrylate can react with the hydroxyl group on the surface of the filler at a later stage to form a firm chemical anchor. Gamma-methacryloxypropyltrimethoxysilane can form a covalent bond with the filler in the rubber, has strong adsorption, reduces the interfacial tension, improves the dispersion performance of the dispersant, and the steric hindrance effect of the siloxane segment further inhibits particle aggregation, improves the compatibility and thermal stability of the dispersant. Further, the synergistic effect of multiple raw materials realizes functional synergy, which can improve the filler-rubber interface bonding, make the filler uniformly distributed in the rubber, and the stress transfer is more effective, thereby significantly improving the mechanical properties of the vulcanized rubber, improving the processing fluidity and saving energy consumption.

[0028] (4) The polycarboxylic acid type dispersant prepared in the application has excellent dispersion performance and high temperature resistance, which is helpful to form a stable dispersion system. In the rubber processing process, the dispersant is not easy to fail in the high temperature vulcanization process, and when the filler is mixed with the rubber, the long-chain polyether side chain and the hydrophilic group of the dispersant quickly infiltrate the filler agglomerates, are firmly adsorbed on the surface of the filler particles through various forces, and the large agglomerates of the filler are effectively disintegrated into primary particles or smaller aggregates, effectively avoiding agglomeration and being uniformly dispersed in the rubber matrix. DETAILED DESCRIPTION

[0029] For the purposes of promoting an understanding of the principles of the application, reference will now be made to the embodiments illustrated in the drawings. There is shown in the drawings, by way of illustration, specific embodiments with which the application can be practiced. The particular embodiments discussed herein are provided by way of example and are not meant to limit the application. Furthermore, the Example 1

[0030] A preparation method of a polycarboxylic acid type dispersant comprises the following steps: Step one, 10g of nanocellulose is dispersed in 90mL of N,N-dimethylformamide, after uniform dispersion, heating, adding 1g of 4-dimethylaminopyridine, stirring and mixing, then adding 28g of hexadecenyl succinic anhydride, stirring and mixing, reacting at 80℃ for 6h, after the reaction is completed, washing with anhydrous ethanol and deionized water, vacuum drying at 60℃ for 24h, to obtain modified cellulose; Step two, 1g of nanosilica is ultrasonically dispersed in 240mL of a buffer solution of acetic acid and sodium acetate with a pH of 3.5, after uniform mixing, adding 45mL of a 0.025mol / L sodium dodecylbenzenesulfonate solution, stirring and mixing, adding chitosan dissolved in an acetic acid solution, wherein the chitosan is 0.8g and the acetic acid solution is a 1wt% acetic acid solution, stirring and mixing for 4h, adding 12mL of glutaraldehyde, stirring, and reacting at 30℃ for 6h, rotary evaporation, to obtain chitosan@silica; Step three, 180mL of a 1wt% acetic acid solution, 10g of chitosan@silica are uniformly mixed, then adding 7g of modified cellulose, 1.5g of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide, and 0.3g of N-hydroxysuccinimide, stirring and mixing, reacting, the reaction temperature is 35℃, the reaction time is 12h, after the reaction is completed, centrifugation, dialysis with deionized water, freeze-drying, to obtain a modified hybrid composite; Step four, 300mL of a mixed solvent, 15g of itaconic acid, 10g of 2-acrylamide-2-methylpropanesulfonic acid, 5g of glycidyl methacrylate, 5mL of methylstyrene, 3g of γ-methacryloyloxypropyltrimethoxysilane, 2g of a modified hybrid composite, 1g of 2-mercapto propionic acid vinyl ester, and 20g of allyl polyoxyethylene ether are mixed, wherein the mixed solvent is composed of isopropyl alcohol and deionized water in a volume ratio of 4:1, heating under a nitrogen atmosphere, adding 0.5g of initiator azobisisobutyronitrile and 0.1g of chain transfer agent dodecanethiol, stirring and mixing, reacting at 70℃ for 6h, after the reaction is completed, cooling, adjusting the pH to 6 using a 30wt% sodium hydroxide aqueous solution, removing the solvent by distillation under reduced pressure, to obtain a polycarboxylic acid type dispersant. Example 2

[0031] A preparation method of a polycarboxylic acid type dispersant comprises the following steps: Step 1: Disperse 10g of nanocellulose into 105mL of N,N-dimethylformamide. After uniform dispersion, heat the solution and add 1.5g of 4-dimethylaminopyridine. Stir and mix, then add 30g of hexadecenylsuccinic anhydride and stir and mix. React at 85℃ for 5h. After the reaction is complete, wash with anhydrous ethanol and deionized water, and vacuum dry at 60℃ for 24h to obtain modified cellulose. Step 2: Disperse 1g of nano-silica ultrasonically into 280mL of a pH 3.5 buffer solution of acetic acid and sodium acetate. After mixing evenly, add 48mL of 0.025mol / L sodium dodecylbenzenesulfonate solution and stir to mix. Add chitosan dissolved in acetic acid solution (0.9g of chitosan and 1wt% acetic acid solution), stir to mix for 4h, add 13mL of glutaraldehyde, stir, react at 35℃ for 5h, and rotary evaporate to obtain chitosan@silica. Step 3: Mix 200 mL of 1 wt% acetic acid solution and 10 g of chitosan@silica evenly, then add 9 g of modified cellulose, 1.8 g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and 0.5 g of N-hydroxysuccinimide, stir and mix, and allow the reaction to proceed. The reaction temperature is 40℃ and the reaction time is 9 h. After the reaction is completed, centrifuge, dialyze with deionized water, and freeze dry to obtain the modified hybrid complex. Step 4: Mix 320 mL of mixed solvent, 18 g of itaconic acid, 14 g of 2-acrylamide-2-methylpropanesulfonic acid, 8 g of glycidyl methacrylate, 6 mL of methylstyrene, 4 g of γ-methacryloyloxypropyltrimethoxysilane, 3.5 g of modified hybrid complex, 1.8 g of 2-mercaptopropionic acid vinyl ester, and 22 g of allyl polyoxyethylene ether. The mixed solvent is composed of isopropanol and deionized water in a volume ratio of 4:1. Under a nitrogen atmosphere, heat the mixture, add 1.2 g of initiator azobisisobutyronitrile and 0.2 g of chain transfer agent dodecanethiol, stir and mix, and react at 75 °C for 5 h. After the reaction is complete, cool the mixture, adjust the pH to 6.5 using a 30 wt% sodium hydroxide aqueous solution, and remove the solvent by vacuum distillation to obtain a polycarboxylic acid type dispersant. Example 3

[0032] A method for preparing a polycarboxylate dispersant includes the following steps: Step 1: Disperse 10g of nanocellulose into 105mL of N,N-dimethylformamide. After uniform dispersion, heat the solution and add 1-2g of 4-dimethylaminopyridine. Stir and mix, then add 32g of hexadecenylsuccinic anhydride and stir and mix. React at 85℃ for 5h. After the reaction is complete, wash with anhydrous ethanol and deionized water, and vacuum dry at 60℃ for 24h to obtain modified cellulose. Step two, 1g nano-silica was dispersed into 280mL buffer solution of acetic acid and sodium acetate with pH value of 3.5, after mixing, 52mL of 0.025mol / L sodium dodecyl benzene sulfonate solution was added, mixed and stirred, 1.1g of chitosan dissolved in 1wt% acetic acid solution was added, mixed and stirred for 4h, 14mL of glutaraldehyde was added, stirred and reacted at 35℃ for 5h, and then rotary evaporation was performed to obtain chitosan@silica; Step three, 200mL of 1wt% acetic acid solution, 10g of chitosan@silica were mixed and stirred, 11g of modified cellulose, 2.1g of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and 0.7g of N-hydroxysuccinimide were added, mixed and stirred, and then reacted at 40℃ for 10h, after the reaction was completed, centrifugation, dialysis with deionized water and freeze-drying were performed to obtain the modified hybrid composite; Step four, 320mL of mixed solvent, 18g of itaconic acid, 14g of 2-acrylamide-2-methylpropanesulfonic acid, 8g of glycidyl methacrylate, 6mL of methylstyrene, 4g of γ-methacryloyloxypropyltrimethoxysilane, 3.5g of modified hybrid composite, 1.8g of 2-mercapto propionic acid vinyl ester and 22g of allyl polyoxyethylene ether were mixed, wherein the mixed solvent was composed of isopropanol and deionized water with a volume ratio of 4:1, under the atmosphere of nitrogen, 1.2g of initiator azobisisobutyronitrile and 0.2g of chain transfer agent dodecanethiol were added, mixed and stirred, and then reacted at 75℃ for 5h, after the reaction was completed, cooling was performed, 30wt% sodium hydroxide aqueous solution was used to adjust the pH value to 6.5, and then distillation was performed under reduced pressure to remove the solvent to obtain the polycarboxylic acid type dispersant. Example 4

[0033] A preparation method of a polycarboxylic acid type dispersant, comprising the following steps: 320mL of mixed solvent, 21g of itaconic acid, 17g of 2-acrylamide-2-methylpropanesulfonic acid, 12g of glycidyl methacrylate, 8mL of methylstyrene, 6g of γ-methacryloyloxypropyltrimethoxysilane, 5g of modified hybrid composite, 2.5g of 2-mercapto propionic acid vinyl ester and 26g of allyl polyoxyethylene ether were mixed, wherein the mixed solvent was composed of isopropanol and deionized water with a volume ratio of 4:1, under the atmosphere of nitrogen, 1.8g of initiator azobisisobutyronitrile and 0.25g of chain transfer agent dodecanethiol were added, mixed and stirred, and then reacted at 75℃ for 5h, after the reaction was completed, cooling was performed, 30wt% sodium hydroxide aqueous solution was used to adjust the pH value to 6.5, and then distillation was performed under reduced pressure to remove the solvent to obtain the polycarboxylic acid type dispersant.

[0034] In this embodiment, the preparation method of the modified hybrid composite is completely consistent with the preparation scheme of the modified hybrid composite in Example 3. Example 5

[0035] A preparation method of a polycarboxylic acid dispersant, comprising the following steps: Step one, 10 g of nanocellulose is dispersed in 120 mL of N,N-dimethylformamide, after uniform dispersion, heating, 2 g of 4-dimethylaminopyridine is added, stirring and mixing, then 35 g of hexadecenyl succinic anhydride is added, stirring and mixing, and reacting at 90°C for 4 h, after the reaction is completed, deionized water and anhydrous ethanol are used for washing, and vacuum drying at 60°C for 24 h to obtain modified cellulose; Step two, 1 g of nanosilica is ultrasonically dispersed in 300 mL of a buffer solution of acetic acid and sodium acetate with a pH of 3.5, after uniform mixing, 55 mL of a 0.025 mol / L sodium dodecylbenzenesulfonate solution is added, stirring and mixing, and 1.2 g of chitosan dissolved in a 1 wt% acetic acid solution is added, stirring and mixing for 4 h, then 15 mL of glutaraldehyde is added, stirring, and reacting at 40°C for 4 h, and rotary evaporation to obtain chitosan@silica; Step three, 210 mL of a 1 wt% acetic acid solution, 10 g of chitosan@silica are uniformly mixed, then 12 g of modified cellulose, 2.5 g of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide, and 0.8 g of N-hydroxysuccinimide are added, stirring and mixing, and reacting, the reaction temperature is 45°C, the reaction time is 8 h, after the reaction is completed, centrifugation, deionized water dialysis, and freeze-drying to obtain a modified hybrid composite; Step four, 350 mL of a mixed solvent, 25 g of itaconic acid, 20 g of 2-acrylamide-2-methylpropanesulfonic acid, 15 g of glycidyl methacrylate, 10 mL of methylstyrene, 8 g of γ-methacryloyloxypropyltrimethoxysilane, 6 g of a modified hybrid composite, 3 g of 2-vinylthiopropionic acid, and 30 g of allyl polyoxyethylene ether are mixed, wherein the mixed solvent is composed of isopropyl alcohol and deionized water in a volume ratio of 4:1, heating, 2 g of initiator azobisisobutyronitrile and 0.3 g of chain transfer agent dodecanethiol are added, stirring and mixing, and reacting at 80°C for 4 h, after the reaction is completed, cooling, adjusting the pH to 7 using a 30 wt% sodium hydroxide aqueous solution, and removing the solvent by reduced pressure distillation to obtain a polycarboxylic acid dispersant.

[0036] Comparative Example 1 A preparation method of a polycarboxylic acid dispersant, comprising the following steps: Step one, 10 g of nanocellulose is dispersed in 105 mL of N,N-dimethylformamide, after uniform dispersion, heating, adding 1-2 g of 4-dimethylaminopyridine, stirring and mixing, then adding 32 g of maleic anhydride, stirring and mixing, reacting at 85°C for 5h, after the reaction is completed, washing with anhydrous ethanol and deionized water, and vacuum drying at 60°C for 24h to obtain modified cellulose; Step two, 320 mL of mixed solvent, 21 g of itaconic acid, 17 g of 2-acrylamide-2-methylpropane sulfonic acid, 12 g of glycidyl methacrylate, 8 mL of methyl styrene, 6 g of γ-methacryloyloxypropyl trimethoxysilane, 1.1 g of nano silicon dioxide, 1.3 g of chitosan, 2.6 g of modified cellulose, 2.5 g of 2-mercapto propionic acid vinyl ester, 26 g of allyl polyoxyethylene ether are mixed, wherein the mixed solvent is composed of isopropyl alcohol and deionized water in a volume ratio of 4:1, in a nitrogen atmosphere, heating, adding 1.8 g of initiator azobisisobutyronitrile and 0.25 g of chain transfer agent dodecanethiol, stirring and mixing, reacting at 75°C for 5h, after the reaction is completed, cooling, adjusting the pH to 6.5 using 30wt% sodium hydroxide aqueous solution, removing the solvent by distillation under reduced pressure to obtain a polycarboxylic acid type dispersant.

[0037] Comparative example 2 A method for preparing a polycarboxylic acid type dispersant, comprising the following steps: 320 mL of mixed solvent, 21 g of itaconic acid, 17 g of 2-acrylamide-2-methylpropane sulfonic acid, 12 g of glycidyl methacrylate, 8 mL of methyl styrene, 6 g of γ-methacryloyloxypropyl trimethoxysilane, 1.1 g of nano silicon dioxide, 1.3 g of chitosan, 2.6 g of nanocellulose, 2.5 g of 2-mercapto propionic acid vinyl ester, 26 g of allyl polyoxyethylene ether are mixed, wherein the mixed solvent is composed of isopropyl alcohol and deionized water in a volume ratio of 4:1, in a nitrogen atmosphere, heating, adding 1.8 g of initiator azobisisobutyronitrile and 0.25 g of chain transfer agent dodecanethiol, stirring and mixing, reacting at 75°C for 5h, after the reaction is completed, cooling, adjusting the pH to 6.5 using 30wt% sodium hydroxide aqueous solution, removing the solvent by distillation under reduced pressure to obtain a polycarboxylic acid type dispersant.

[0038] Comparative example 3 A method for preparing a polycarboxylic acid type dispersant, comprising the following steps: A mixture of 320 mL of mixed solvent, 21 g of itaconic acid, 17 g of 2-acrylamido-2-methylpropane sulfonic acid, 8 mL of methylstyrene, 6 g of γ-methacryloxypropyltrimethoxysilane, 5 g of modified hybrid composite, 2.5 g of 2-mercapto propionic acid vinyl ester, and 26 g of allyl polyoxyethylene ether, wherein the mixed solvent is composed of isopropyl alcohol and deionized water in a volume ratio of 4:1, is mixed, and 1.8 g of an initiator, azobisisobutyronitrile, and 0.25 g of a chain transfer agent, dodecanethiol, are added under a nitrogen atmosphere. The mixture is stirred and reacted at 75°C for 5 h. After the reaction is completed, the mixture is cooled, the pH is adjusted to 6.5 using a 30 wt% aqueous sodium hydroxide solution, and the solvent is removed by distillation under reduced pressure to obtain a polycarboxylic acid-type dispersant.

[0039] Comparative Example 4 A method of preparing a polycarboxylic acid-type dispersant includes the following steps: A mixture of 320 mL of mixed solvent, 21 g of itaconic acid, 17 g of 2-acrylamido-2-methylpropane sulfonic acid, 8 mL of methylstyrene, 6 g of γ-methacryloxypropyltrimethoxysilane, 5 g of modified hybrid composite, 2.5 g of 2-mercapto propionic acid vinyl ester, and 26 g of allyl polyoxyethylene ether, wherein the mixed solvent is composed of isopropyl alcohol and deionized water in a volume ratio of 4:1, is mixed, and 1.8 g of an initiator, azobisisobutyronitrile, and 0.25 g of a chain transfer agent, dodecanethiol, are added under a nitrogen atmosphere. The mixture is stirred and reacted at 75°C for 5 h. After the reaction is completed, the mixture is cooled, the pH is adjusted to 6.5 using a 30 wt% aqueous sodium hydroxide solution, and the solvent is removed by distillation under reduced pressure to obtain a polycarboxylic acid-type dispersant.

[0040] In the present comparative example, the method of preparing the modified hybrid composite is identical to the method of preparing the modified hybrid composite in Example 3.

[0041] Comparative Example 5 A method of preparing a polycarboxylic acid-type dispersant includes the following steps: A mixture of 320 mL of mixed solvent, 21 g of itaconic acid, 17 g of 2-acrylamido-2-methylpropane sulfonic acid, 8 mL of methylstyrene, 6 g of γ-methacryloxypropyltrimethoxysilane, 5 g of modified hybrid composite, 2.5 g of 2-mercapto propionic acid vinyl ester, and 26 g of allyl polyoxyethylene ether, wherein the mixed solvent is composed of isopropyl alcohol and deionized water in a volume ratio of 4:1, is mixed, and 1.8 g of an initiator, azobisisobutyronitrile, and 0.25 g of a chain transfer agent, dodecanethiol, are added under a nitrogen atmosphere. The mixture is stirred and reacted at 75°C for 5 h. After the reaction is completed, the mixture is cooled, the pH is adjusted to 6.5 using a 30 wt% aqueous sodium hydroxide solution, and the solvent is removed by distillation under reduced pressure to obtain a polycarboxylic acid-type dispersant.

[0042] The preparation method of the modified hybrid composite in the present comparative example is completely consistent with the preparation scheme of the modified hybrid composite in Example 3.

[0043] The nanosilica used in the examples and comparative examples of the present application was purchased from Lianyungang Pengrui Chemical Co., Ltd. of Jiangsu, with an average particle size of 15 nm; the nanocellulose was purchased from Funan New Material Technology (Shanghai) Co., Ltd.; the chitosan was purchased from National Pharmaceutical Group Chemical Reagent Co., Ltd.; the allyl polyoxyethylene ether was APEG1000, purchased from Haian Petroleum Chemical Plant of Jiangsu; and other unexplained raw materials and reagents were commercially available.

[0044] Performance test (1) The high-temperature resistance of the polycarboxylic acid dispersant prepared in Examples 1-5 and Comparative Examples 1-5 was tested according to GB / T 27761-2011 “Thermogravimetric Analyzer Weight Loss and Residual Test Method”, using a TA Q500 thermogravimetric analyzer, in a nitrogen atmosphere, with a heating rate of 10℃ / min, a test temperature range of 30-800℃, and a test of 5% weight loss temperature (Td 5% ) and maximum weight loss temperature (Td max ). The test results are shown in Table 1: Table 1 Test item Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Td 5% (°C) 293 302 305 310 303 271 264 255 285 273 Td max (°C) 381 393 398 405 390 361 350 337 372 364 According to the test results in Table 1, it can be seen that the polycarboxylic acid dispersant prepared by the synergistic effect of the raw materials in Examples 1-5 has excellent high-temperature resistance and thermal stability, Td 5% and Td max are significantly higher than those of the comparative examples. In Comparative Example 1, maleic anhydride was used to modify cellulose, and nanosilica and chitosan were directly added, resulting in a decrease in heat resistance. In Comparative Example 2, the nanocellulose was not modified, and the nanocellulose, nanosilica and chitosan were directly added to the matrix, resulting in lower high-temperature resistance and thermal stability than Comparative Example 1. In Comparative Example 3, no modified hybrid composite was added, resulting in a significant decrease in heat resistance. In Comparative Example 4, no glycidyl methacrylate was added, and in Comparative Example 5, no γ-methacryloyloxypropyltrimethoxysilane was added, resulting in a decrease in heat resistance.

[0045] (2) Using the polycarboxylic acid dispersant in Examples 1-5 and Comparative Examples 1-5 as dispersants, vulcanized rubber samples were prepared as follows: using an XSM-500 type internal mixer, initial temperature 80°C, rotation speed 60 r / min, first adding 100 parts of NR (SCR5) and plasticizing for 2 min, then adding 5 parts of zinc oxide, 2 parts of stearic acid, adding the polycarboxylic acid dispersant in Examples 1-5 and Comparative Examples 1-5 respectively, mixing for 3 min, adding 50 parts of carbon black N330 and mixing for 5 min, finally adding 2 parts of sulfur and 1 part of accelerator CZ and mixing for 2 min, the discharge temperature was ≤110°C, using XK-160 type open mill, roller temperature 50-60°C, the internal mixed rubber was pressed into a rubber sheet with a thickness of 2 mm, cut into samples, according to the vulcanization time (t90) measured by a rotorless vulcanization instrument, the samples were vulcanized at 150°C x t90 using a flat vulcanization machine to obtain vulcanized rubber samples, which were recorded as samples 1-10, and the vulcanized rubber samples prepared under the same conditions without adding dispersants were recorded as blank samples, the dispersion of samples 1-10 and blank samples was tested, the test method was according to GB / T 6030-2006 "Evaluation of Carbon Black and Carbon Black / Silica Dispersion in Rubber by Rapid Comparison Method", and the test results are shown in Table 2: Table 2 Test item Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 Sample 6 Sample 7 Sample 8 Sample 9 Sample 10 Blank sample Dispersion level 8.57 8.85 8.94 9.01 8.87 8.43 8.09 7.78 8.25 8.44 7.47 According to the test results in Table 2, it can be seen that the polycarboxylic acid dispersants corresponding to Examples 1-5 in the present application have excellent dispersion performance, and the dispersion level of sample 4 can reach 9.01. The dispersant used in sample 6 uses maleic anhydride modified cellulose, which has certain dispersion capacity, but the effect is lower than that of sample 4. In sample 7, nanocellulose, nanosilica and chitosan are directly added to the dispersant matrix, and the dispersion level is greatly reduced. In sample 8, no modified hybrid compound is added, and the dispersion performance is greatly reduced. Sample 9 lacks glycidyl methacrylate, and sample 10 lacks γ-methacryloyloxypropyl trimethoxysilane, the compatibility of the dispersant with rubber is poor, and the dispersion performance is reduced.

[0046] Although the embodiments of the present application have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present application, and any equivalent changes and improvements made within the scope of the present application should still be included within the scope of the present application.

Claims

1. A method for producing a polycarboxylic acid type dispersant, characterized by: It comprises the following steps: Step one, disperse nanocellulose into N,N-dimethylformamide, after uniform dispersion, heat, add 4-dimethylaminopyridine, stir and mix, then add alkenyl succinic anhydride, stir and mix, react, after the reaction is completed, wash, dry, and obtain modified cellulose; Step two, ultrasonic dispersion of nanosilica into the mixed solution, after uniform mixing, add sodium dodecyl benzene sulfonate solution, stir and mix, add chitosan dissolved in acetic acid solution, stir and mix for 4h, add glutaraldehyde, stir and react for 4-6h, rotary evaporation, and obtain chitosan@silica; Step three, mix acetic acid solution and chitosan@silica uniformly, then add modified cellulose, 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide, and N-hydroxysuccinimide, stir and mix, react, after the reaction is completed, centrifugal, freeze-drying, and obtain modified hybrid composite; Step four, mix mixed solvent, itaconic acid, 2-acrylamide-2-methylpropanesulfonic acid, glycidyl methacrylate, methyl styrene, gamma-methacryloyloxypropyl trimethoxysilane, modified hybrid composite, 2-mercapto propionic acid vinyl ester, and allyl polyoxyethylene ether, heat in nitrogen atmosphere, add initiator and chain transfer agent, stir and mix, react, after the reaction is completed, cool, adjust pH to 6-7 using sodium hydroxide aqueous solution, and distill under reduced pressure to obtain polycarboxylic acid type dispersant.

2. The method for preparing polycarboxylic acid dispersant according to claim 1, characterized in that: In step one, the addition ratio of nanocellulose, N,N-dimethylformamide, 4-dimethylaminopyridine, and alkenyl succinic anhydride is 10g:90-120mL:1-2g:28-35g, the reaction temperature is 80-90℃, and the reaction time is 4-6h.

3. The method for preparing a polycarboxylate dispersant according to claim 1, characterized in that: In step one, the alkenyl succinic anhydride is any one of alkyl long-chain alkenyl succinic anhydride, including hexadecenyl succinic anhydride, tetradecenyl succinic anhydride, and dodecenyl succinic anhydride.

4. The method for preparing a polycarboxylate dispersant according to claim 1, characterized in that: In step two, the addition ratio of nanosilica, mixed solution, sodium dodecyl benzene sulfonate solution, chitosan, and glutaraldehyde is 1g:240-300mL:45-55mL:0.8-1.2g:12-15mL, and the reaction temperature is 30-40℃.

5. The method for preparing a polycarboxylate dispersant according to claim 1, characterized in that: In step three, the addition ratio of acetic acid solution, chitosan@silica, modified cellulose, 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide, and N-hydroxysuccinimide is 180-210mL:10g:7-12g:1.5-2.5g:0.3-0.8g, the reaction temperature is 35-45℃, and the reaction time is 8-12h.

6. The method for preparing a polycarboxylate dispersant according to claim 1, characterized in that: The addition ratio of the mixed solvent, itaconic acid, 2-acrylamide-2-methylpropanesulfonic acid, glycidyl methacrylate, methylstyrene, γ-methacryloyloxypropyltrimethoxysilane, modified hybrid compound, 2-mercapto propionic acid vinyl ester, allyl polyoxyethylene ether, initiator, chain transfer agent in the step four is 300-350 mL: 15-25 g: 10-20 g: 5-15 g: 5-10 mL: 3-8 g: 2-6 g: 1-3 g: 20-30 g: 0.5-2 g: 0.1-0.3 g, the reaction temperature is 70-80 ℃, and the reaction time is 4-6 h.

7. The method for preparing a polycarboxylate dispersant according to claim 1, characterized in that: The initiator in the step four is azobisisobutyronitrile.

8. The method for preparing a polycarboxylate dispersant according to claim 1, characterized in that: The chain transfer agent in the step four is dodecanethiol.

9. A polycarboxylic dispersant prepared by the method according to any one of claims 1-8.

10. Use of the polycarboxylic dispersant according to claim 9 in rubber processing.