Preparation method of high-molecular-weight waste rubber powder carboxylation modified and dynamically crosslinked rubber

Abstract

The invention discloses a preparation method of high molecular weight waste rubber powder carboxylation modification and dynamic cross-linked rubber, and belongs to the technical field of high molecular weight waste rubber powder carboxylation modification and dynamic cross-linked rubber preparation. The preparation method comprises the following steps: S1, dispersing high-molecular-weight waste rubber powder in a solvent, adding acrylic acid and an initiator, and heating and stirring to obtain carboxylated waste rubber powder; s2, plastifying the matrix rubber on an open mill for roll coating, adding the carboxylated waste rubber powder in batches, and adding a cross-linking agent and an anti-aging agent at the same time to obtain masterbatch; s3, putting the master batch into an internal mixer, raising the temperature of the master batch to a preset dynamic crosslinking temperature, adding sulfur, an accelerant and other vulcanizing aids, and vulcanizing. Compared with the prior art, reversible chemical bonds can be formed at the interface of rubber powder particles and matrix rubber, and the chemical bonds can be temporarily broken during high-temperature processing and can be re-formed after cooling, so that the strength and the elasticity of the material are recovered.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of high molecular weight waste rubber powder carboxylation modification and dynamic crosslinking rubber preparation, and particularly relates to a preparation method of high molecular weight waste rubber powder carboxylation modification and dynamic crosslinking rubber. BACKGROUND

[0002] Rubber products are widely used in various aspects of people's life. A large amount of waste and leftover materials are generated in the production process of rubber products. Rubber products have the characteristics of short service life and frequent replacement. A large amount of waste and old rubber is also generated when the rubber products reach the service life. For these waste and old rubber, the traditional treatment method is mainly landfill. This treatment method not only pollutes the environment but also wastes resources.

[0003] Waste rubber powder refers to a powder material of a certain particle size obtained by physically processing waste and old rubber products through crushing and grinding. In traditional rubber recycling, the rubber powder obtained by simply crushing the waste rubber is directly mixed into new rubber. Since the surface of the rubber powder is inert, the interface between the rubber powder and the new rubber matrix is weak. Meanwhile, the rubber powder itself is a three-dimensional crosslinking network and cannot form chemical bonding with the network of the new rubber, thus becoming a stress concentration point. This will result in a significant decrease in the mechanical properties of the composite material, greatly reducing the tensile strength, elasticity, wear resistance and fatigue resistance of the reclaimed rubber.

[0004] Therefore, in view of the above technical problems, it is necessary to provide a preparation method of high molecular weight waste rubber powder carboxylation modification and dynamic crosslinking rubber.

[0005] The information disclosed in the background section of this document is only intended to increase the understanding of the general background of the application and should not be considered as an acknowledgment or any form of suggestion that this information constitutes prior art that is known to those skilled in the art. SUMMARY

[0006] The purpose of the present application is to provide a preparation method of high molecular weight waste rubber powder carboxylation modification and dynamic crosslinking rubber, which can solve the problem of reduced physical and mechanical properties such as tensile strength, elasticity, wear resistance and fatigue resistance of reclaimed rubber.

[0007] In order to achieve the above-mentioned purpose, a preparation method of high molecular weight waste rubber powder carboxylation modification and dynamic crosslinking rubber according to an embodiment of the present application comprises the following steps:

[0008] S1, adding a solvent into a reaction kettle, dispersing high molecular weight waste rubber powder in the solvent, then adding an acrylic acid and an initiator into the reaction kettle, heating and stirring under the protection of inert gas, after the reaction is completed, removing homopolymer by extraction with a precipitant, and then drying to obtain carboxylated waste rubber powder;

[0009] S2, the base rubber is plasticized on the open mill, and the roll is wrapped, and the rubber is preheated and plasticized, and the carboxylated waste rubber powder is added in batches, and the crosslinking agent and the antioxidant are added, and the rubber is mixed uniformly, and the rubber is wrapped and placed for 8 hours, and then the rubber is placed in a preheated mold and vulcanized on a flat vulcanizing machine.

[0010] S3, the masterbatch is put into the internal mixer, the temperature of the masterbatch is raised to the preset dynamic crosslinking temperature, the vulcanizing aid such as sulfur and accelerator is added, and the rubber is mixed uniformly, and the rubber is wrapped and placed for 8 hours, and then the rubber is placed in a preheated mold and vulcanized on a flat vulcanizing machine.

[0011] In one or more embodiments of the present application, the S1 high molecular weight waste rubber powder preparation comprises the following steps:

[0012] S11, the waste rubber is placed in a deep cold environment below-80℃ to make it brittle, and is mechanically pulverized, and the waste rubber powder with a mesh size of 40-100 is screened;

[0013] S12, the waste rubber powder is placed in a Soxhlet extractor, and acetone is used for extraction for 24-48 hours, and after taking out, it is fully dried in a vacuum drying oven at 60℃.

[0014] In one or more embodiments of the present application, the solvent in S1 is one of xylene or toluene.

[0015] In one or more embodiments of the present application, the initiator in S1 is one of dibenzoyl peroxide, dicumyl peroxide or potassium persulfate.

[0016] In one or more embodiments of the present application, the mass ratio of the dried waste rubber powder to the solvent in S1 is 1:10.

[0017] In one or more embodiments of the present application, the heating temperature in S1 is 80-90℃.

[0018] In one or more embodiments of the present application, the base rubber in S2 is one of natural rubber, styrene-butadiene rubber or butadiene rubber.

[0019] In one or more embodiments of the present application, the carboxylated waste rubber powder in S2 is added in an amount of 20-60% of the mass of the base rubber.

[0020] In one or more embodiments of the present application, the crosslinking agent in S2 is one of zinc oxide or stearic acid.

[0021] In one or more embodiments of the present application, the dynamic crosslinking temperature in S3 is 140-160℃.

[0022] Compared with the prior art, the preparation method of the high molecular weight waste rubber powder carboxylated modified and dynamically crosslinked rubber of the present application improves the compatibility and reactivity of the waste rubber powder with polar rubber or rubber containing reactive functional groups by introducing active carboxyl functional groups on the surface of the waste rubber powder particles, utilizes the dynamic covalent crosslinking reaction of carboxyl and crosslinking agent to form "reversible" chemical bonds at the interface between the rubber powder particles and the matrix rubber, these chemical bonds will temporarily break during high temperature processing, allowing the material to flow and re-form, and after cooling, the chemical bonds can be re-formed again, restoring the strength and elasticity of the material, thereby preparing a high-performance rubber composite material with excellent performance and repeated processing regeneration. DETAILED DESCRIPTION

[0023] In order for those skilled in the art to better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application are described clearly and completely. Obviously, the described embodiments are only some of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should be within the scope of protection of the present application.

[0024] Embodiment 1

[0025] A preparation method of high molecular weight waste rubber powder carboxylated modified and dynamically crosslinked rubber, comprising the following steps:

[0026] S1, xylene is added to the reaction kettle, the high molecular weight waste rubber powder is dispersed in xylene, the mass ratio of dry waste rubber powder to xylene is adjusted to 1:10, stirring is started, nitrogen is introduced for protection, oxygen in the system is removed to prevent oxygen from consuming dibenzoyl peroxide and inhibiting free radical reaction, then acrylic acid and dibenzoyl peroxide are added to the reaction kettle, the temperature is raised to 140℃, the rubber powder is fully swollen for 1 hour, the system temperature is reduced to 80℃, and the reaction is continued at this temperature for 6 hours to ensure that the grafting reaction is fully carried out, after the reaction is completed, the reaction mixture is cooled to room temperature, the mixture is slowly poured into 5 times the volume of methanol precipitant, stirring is carried out while pouring, the modified rubber powder will precipitate in the form of floccules, the precipitate is collected by suction filtration, the precipitate is washed with fresh methanol for several times to wash away unreacted acrylic acid, homopolymer and residual dibenzoyl peroxide, and the washed modified rubber powder is dried in a vacuum drying oven at 60℃ to obtain the finished carboxylated waste rubber powder;

[0027] S2, roll plasticizing of natural rubber on the open mill, thin pass several times, preheating plasticization, batch adding carboxylated waste rubber powder, constantly punching triangle bag or cutting knife during powder eating to ensure uniform dispersion of fillers, the amount of rubber powder can be 20% of the mass of natural rubber, while adding zinc oxide, antioxidant, mixing uniformly, the mixing temperature is recommended to control at 110℃, to facilitate the dispersion of rubber powder but avoid premature crosslinking, finally adding sulfur or dicumyl peroxide, control the roller temperature to prevent scorching, thin pass the sheet, get the masterbatch;

[0028] S3, put the masterbatch into the internal mixer, raise the temperature of the masterbatch to the preset dynamic crosslinking temperature 140℃, add sulfur, accelerator (such as dibutyltin dilaurate) and other vulcanizing aids, continue mixing at this temperature for 8 minutes, mix uniformly, the torque of the internal mixer will first rise and then reach a balance platform, which marks the occurrence and completion of dynamic crosslinking reaction, after the rubber compound is sheeted, it is placed for 8 hours, then put the rubber compound into the preheated mold and vulcanize on the flat vulcanizing machine, the vulcanization conditions are: temperature 150℃, pressure 15MPa.

[0029] Among them, the preparation of high molecular weight waste rubber powder includes the following steps:

[0030] S11, sort, wash and remove fibers and steel wires from waste tires or rubber products, then roughly crush into rubber blocks, send these rubber blocks into a freezing tunnel or a spiral freezer, quickly cool to a brittle temperature below-80℃ through direct or indirect contact with liquid nitrogen, brittle rubber blocks enter a high-speed hammer mill or an impact crusher for mechanical crushing, the crushed material is screened to obtain rubber powder of 40-100 mesh, and residual steel wires and fibers are removed by magnetic separation and air separation.

[0031] S12, place the waste rubber powder in a Soxhlet extractor, extract with acetone for 24 hours to remove surface oil stains, antioxidants and other small molecular impurities, after taking out, fully dry in a 60℃ vacuum drying oven to completely remove water.

[0032] Example 2

[0033] A preparation method of high molecular weight waste rubber powder carboxylation modification and dynamic crosslinking rubber, including the following steps:

[0034] S1, add xylene into the reaction kettle, disperse the high molecular weight waste rubber powder in xylene, adjust the mass ratio of dry waste rubber powder and xylene to 1:10, start stirring, protect with nitrogen, remove oxygen in the system to prevent oxygen from consuming dicumyl peroxide and inhibiting free radical reaction, then add acrylic acid and dicumyl peroxide into the reaction kettle, heat to 140℃, make the rubber powder swell for 2 hours, reduce the temperature of the system to 90℃, continue to react at this temperature for 4 hours to ensure that the grafting reaction is fully carried out, after the reaction is completed, cool the reaction mixture to room temperature, slowly pour the mixture into 10 times the volume of methanol precipitant, stir while pouring, the modified rubber powder will precipitate in the form of floccules, collect the precipitate by suction filtration, wash the precipitate with fresh methanol several times to wash away unreacted acrylic acid, homopolymer and residual dicumyl peroxide, dry the washed modified rubber powder in a vacuum drying oven at 70℃ to obtain the carboxylated waste rubber powder product;

[0035] S2, plasticize the butadiene styrene rubber on the open mill, pass it several times, preheat and plasticize, add the carboxylated waste rubber powder in batches, constantly punch the triangle bag or cut the knife during the powder feeding process to ensure uniform dispersion of the filler, the rubber powder addition amount can be 60% of the mass of the butadiene styrene rubber, at the same time, add stearic acid and antioxidant, mix evenly, the mixing temperature is recommended to be controlled at 130℃ to facilitate the dispersion of the rubber powder but avoid premature crosslinking, finally add sulfur or dicumyl peroxide, control the roll temperature to prevent scorching, pass the sheet to obtain the masterbatch;

[0036] S3, put the masterbatch into the internal mixer, raise the temperature of the masterbatch to the preset dynamic crosslinking temperature of 160℃, add sulfur, accelerator (such as dibutyltin dilaurate) and other curing aids, continue to mix at this temperature for 15 minutes, mix evenly, the torque of the internal mixer will first rise and then reach a balance platform, which marks the occurrence and completion of the dynamic crosslinking reaction, after the rubber compound is sheeted, it is parked for 8 hours, then it is put into a preheated mold and vulcanized on a flat vulcanizing machine, the vulcanization conditions are: temperature 160℃, pressure 10MPa.

[0037] The preparation of the high molecular weight waste rubber powder includes the following steps:

[0038] S11, sort, wash and remove fibers and steel wires from the waste tires or rubber products, then roughly crush them into rubber blocks, send these rubber blocks into a refrigeration tunnel or a spiral freezer, rapidly cool them to a brittle temperature below -80℃ through direct or indirect contact with liquid nitrogen, make the brittle rubber blocks enter a high-speed hammer mill or an impact crusher for mechanical crushing, screen the crushed materials to obtain rubber powder with a size of 40-100 mesh, and remove the residual steel wires and fibers through magnetic separation and air separation.

[0039] S12, the waste rubber powder is placed in a soxhlet extractor, and extracted with acetone for 48 hours to remove small molecular impurities such as surface oil stains and anti-aging agents, and after being taken out, is fully dried in a vacuum drying oven at 60°C to completely remove moisture.

[0040] Example 3

[0041] A preparation method of high molecular weight waste rubber powder carboxylation modification and dynamic crosslinking rubber, comprising the following steps:

[0042] S1, toluene is added to the reaction kettle, and the high molecular weight waste rubber powder is dispersed in toluene, the mass ratio of dry waste rubber powder and toluene is adjusted to 1:10, stirring is started, nitrogen is introduced for protection to exclude oxygen in the system, to prevent the consumption of potassium persulfate by oxygen and inhibit the free radical reaction, then acrylic acid and potassium persulfate are added to the reaction kettle, the temperature is raised to 140°C, and the rubber powder is fully swelled for 1.5 hours, then the system temperature is reduced to 85°C, and the reaction is continued at this temperature for 5 hours to ensure that the grafting reaction is fully carried out, after the reaction is completed, the reaction mixture is cooled to room temperature, and the mixture is slowly poured into 8 times the volume of methanol precipitant while stirring, the modified rubber powder will precipitate in the form of floccules, the precipitate is collected by suction filtration, and the precipitate is washed with fresh methanol for several times to wash away unreacted acrylic acid, homopolymer and residual potassium persulfate, and the washed modified rubber powder is dried in a vacuum drying oven at 65°C to obtain the finished carboxylated waste rubber powder;

[0043] S2, the butadiene rubber is plasticized and wrapped on the roll on the open mill, and is passed through several times to preheat and plasticize, the carboxylated waste rubber powder is added in batches, and the triangular bag or cutter is continuously punched during the powder feeding process to ensure uniform dispersion of the filler, the amount of the rubber powder can be 40% of the mass of the butadiene rubber, stearic acid and anti-aging agents are added at the same time, and mixing is uniform, the mixing temperature is recommended to be controlled at 120°C to facilitate dispersion of the rubber powder but avoid premature crosslinking, and finally, sulfur or dicumyl peroxide is added, the roll temperature is controlled to prevent scorching, and the sheet is passed through to obtain the masterbatch;

[0044] S3, the masterbatch is put into the internal mixer, the temperature of the masterbatch is raised to the preset dynamic crosslinking temperature of 150°C, sulfur, accelerant (such as dibutyltin dilaurate) and other vulcanizing aids are added, and mixing is continued at this temperature for 12 minutes, and the mixing is uniform, and the torque of the internal mixer first rises and then reaches a balance platform, which indicates that the dynamic crosslinking reaction occurs and is completed, the rubber is placed after the sheet is passed through and stopped for 8 hours, and then the rubber is put into a preheated mold and vulcanized on a flat vulcanizing machine, and the vulcanization conditions are: temperature 155°C and pressure 12 MPa.

[0045] The preparation of the high molecular weight waste rubber powder comprises the following steps:

[0046] S11, sorting, washing and removing fibers and steel wires from waste tires or rubber products, then roughly crushing into rubber blocks, sending the rubber blocks into a freezing tunnel or a spiral freezer, rapidly cooling to a brittle temperature below -80℃ through direct or indirect contact with liquid nitrogen, brittle rubber blocks entering a high-speed hammer mill or an impact crusher for mechanical crushing, and the crushed material being screened to obtain rubber powder of 40-100 mesh, and removing residual steel wires and fibers through magnetic separation and air separation.

[0047] S12, placing the waste rubber powder into a Soxhlet extractor, extracting using acetone for 32 hours to remove small molecular impurities such as oil stains and anti-aging agents, and after taking out, fully drying in a vacuum drying oven at 60℃ to completely remove water.

[0048] Example 4

[0049] A preparation method of high molecular weight waste rubber powder carboxylated modification and dynamic crosslinking rubber, comprising the following steps:

[0050] S1, toluene is added to the reaction kettle, and the high molecular weight waste rubber powder is dispersed in toluene, the mass ratio of dry waste rubber powder and toluene is adjusted to 1:10, stirring is started, nitrogen is introduced for protection, oxygen in the system is removed to prevent the consumption of potassium persulfate and inhibit the free radical reaction, then acrylic acid and potassium persulfate are added to the reaction kettle, the temperature is raised to 140℃, and the rubber powder is fully swollen for 1 hour, then the system temperature is reduced to 80℃, and the reaction is continued at this temperature for 6 hours to ensure that the grafting reaction is fully carried out, after the reaction is completed, the reaction mixture is cooled to room temperature, the mixture is slowly poured into a 5-fold volume of methanol precipitant, stirring is carried out while pouring, the modified rubber powder is precipitated in the form of floccules, the precipitate is collected by suction filtration, the precipitate is washed with fresh methanol for multiple times to wash away unreacted acrylic acid, homopolymer and residual potassium persulfate, and the washed modified rubber powder is dried in a vacuum drying oven at 60℃ to obtain carboxylated waste rubber powder finished product;

[0051] S2, the butadiene rubber is plasticized on the open mill, and the roll is wrapped several times, preheated and plasticized, the carboxylated waste rubber powder is added in batches, the triangular bag or cutter is constantly punched during the powder feeding process to ensure uniform dispersion of the filler, the rubber powder addition amount can be 20% of the mass of the butadiene rubber, stearic acid and anti-aging agent are added at the same time, and mixing is uniform, the mixing temperature is recommended to be controlled at 110℃ to facilitate dispersion of the rubber powder but avoid premature crosslinking, and finally sulfur or dicumyl peroxide is added, the roll temperature is controlled to prevent scorching, and the sheet is wrapped to obtain the masterbatch;

[0052] S3, the masterbatch is put into the internal mixer, the temperature of the masterbatch is increased to the preset dynamic crosslinking temperature 140℃, sulfur, accelerant (such as dibutyltin dilaurate) and other vulcanizing aids are added, and the mixing is continued for 8 minutes at the temperature, the mixing is uniform, and the torque of the internal mixer will first increase and then reach a balance platform, which indicates the occurrence and completion of the dynamic crosslinking reaction, the rubber is placed after sheeting for 8 hours, and the rubber is placed in a preheated mold for vulcanization on a flat vulcanizing machine, and the vulcanization conditions are as follows: temperature 150℃, and pressure 15MPa.

[0053] The preparation of the high molecular weight waste rubber powder comprises the following steps:

[0054] S11, the waste tires or rubber products are sorted, washed and removed of fibers and steel wires, and then roughly crushed into rubber blocks, the rubber blocks are sent into a refrigeration tunnel or a spiral refrigeration machine, and are rapidly cooled to a brittle temperature below-80℃ through direct or indirect contact with liquid nitrogen, the brittle rubber blocks enter a high-speed hammer mill or an impact crusher for mechanical crushing, and the crushed materials are screened to obtain rubber powder with a size of 40-100 mesh, and the residual steel wires and fibers are removed through magnetic separation and air separation.

[0055] S12, the waste rubber powder is placed in a Soxhlet extractor, and is extracted with acetone for 24 hours to remove small molecular impurities such as oil stains and anti-aging agents, and after being taken out, is fully dried in a vacuum drying oven at 60℃ to completely remove water.

[0056] It is apparent to those skilled in the art that the present application is not limited to the details of the foregoing exemplary embodiments, and the present application can be implemented in other concrete forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be considered in all aspects as illustrative and not restrictive, and the scope of the present application is defined by the appended claims rather than the foregoing description, and all changes falling within the meaning and range of equivalents of the essential elements of the claims are intended to be encompassed by the present application.

[0057] In addition, it should be understood that although the present specification is described in terms of embodiments, not every embodiment contains only one independent technical solution, and the description of the specification is only for the sake of clarity, and those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be properly combined to form other embodiments that those skilled in the art can understand.

Claims

1. A method for preparing high molecular weight waste rubber powder carboxylated modified and dynamically crosslinked rubber, characterized by, It comprises the following steps: S1, add solvent to the reaction kettle, disperse the high molecular weight waste rubber powder in the solvent, then add the acrylic acid and initiator into the reaction kettle, heat and stir under inert gas protection, after the reaction, remove the homopolymer by extraction with precipitant, then dry to obtain carboxylated waste rubber powder; S2, plasticize the base rubber on the open mill, thin pass several times, preheat and plasticize, add carboxylated waste rubber powder in batches, add crosslinking agent and antioxidant, mix evenly, thin pass, and obtain masterbatch; S3, put the masterbatch into the internal mixer, raise the temperature of the masterbatch to the preset dynamic crosslinking temperature, add sulfur, accelerator and other curing aids, mix evenly, and place the rubber after sheeting for 8 hours, then put the rubber into the preheated mold and vulcanize on the flat vulcanizing machine.

2. The method of claim 1, wherein the method is characterized by, The preparation of the high molecular weight waste rubber powder in S1 comprises the following steps: S11, place the waste rubber in a deep cold environment below-80℃ to make it brittle, mechanically crush it, and screen the waste rubber powder with a size of 40-100 mesh; S12, place the waste rubber powder in a Soxhlet extractor, extract it with acetone for 24-48 hours, and then fully dry it in a vacuum drying oven at 60℃.

3. The method of claim 1, wherein the method is characterized by, The solvent in S1 is one of xylene or toluene.

4. The method of claim 3, wherein the carboxylated and dynamically crosslinked rubber is prepared by the steps of: a) mixing the high molecular weight waste rubber powder with a carboxylic acid or a carboxylic acid derivative; b) mixing the high molecular weight waste rubber powder with a crosslinking agent; and c) mixing the high molecular weight waste rubber powder with a crosslinking initiator. The initiator in S1 is one of dibenzoyl peroxide, dicumyl peroxide or potassium persulfate.

5. The method for preparing high molecular weight waste rubber powder carboxylation modification and dynamic crosslinking rubber according to claim 4, characterized in that, The mass ratio of dried waste rubber powder to solvent in S1 is 1:

10.

6. The method for preparing high molecular weight waste rubber powder carboxylation modification and dynamic crosslinking rubber according to claim 5, characterized in that, The heating temperature in S1 is 80-90℃.

7. The method for preparing high molecular weight waste rubber powder carboxylation modification and dynamic crosslinking rubber according to claim 1, characterized in that, The base rubber in S2 is one of natural rubber, styrene-butadiene rubber or cis-butadiene rubber.

8. The method for preparing high molecular weight waste rubber powder carboxylation modification and dynamic crosslinking rubber according to claim 7, characterized in that, The addition amount of carboxylated waste rubber powder in S2 is 20-60% of the mass of the base rubber.

9. The method for preparing a high molecular weight waste rubber powder carboxylation modified and dynamically crosslinked rubber according to claim 8, characterized in that, The crosslinking agent in S2 is one of zinc oxide or stearic acid.

10. The method for preparing a high molecular weight waste rubber powder carboxylation modified and dynamically crosslinked rubber according to claim 9, characterized in that, The dynamic crosslinking temperature in S3 is 140-160℃.