Preparation method of green and environment-friendly regenerated rubber

Abstract

The invention provides a preparation method of green and environment-friendly regenerated rubber, and belongs to the field of regenerated rubber manufacturing. The method comprises the following steps: putting waste rubber powder and a biomass material into a first stirring and mixing device, discharging after the material is heated to a set temperature, feeding the material into a second stirring and mixing device, stirring under the condition of introducing an inert gas atmosphere, and discharging after the material is heated to a set temperature; feeding the materials into a first double-screw extruder through a continuous closed conveying device, controlling the temperature of the screw extruder to be 100-160 DEG C, and completing a depolymerization reaction within 3-7 minutes; and feeding into a second screw extruder through a continuous closed conveying device, controlling the temperature of the second screw extruder to be 5-25 DEG C, cooling for 2-5 minutes, removing impurities through a filtering device, and carrying out thin-passing and sheet discharging through a double-roller refiner, so as to obtain the green and environment-friendly regenerated rubber material. According to the method disclosed by the invention, the rubber regenerant and the softening agent which are derived from biomass are used as regeneration auxiliaries, the depolymerization regeneration of the waste rubber is realized under a low-temperature condition, and the regeneration process is low in energy consumption and small in environmental pollution.

Description

Technical Field

[0001] The invention relates to a low-carbon processing and manufacturing technology, in particular to a method for preparing green and environmentally friendly recycled rubber, and belongs to the technical field of recycled rubber manufacturing. Background Art

[0002] With the development of social economy, a large amount of waste rubber has been produced, which has brought great pressure to resources and the environment. How to efficiently and greenly recycle waste rubber is one of the great challenges currently faced by polymer science and the rubber industry. At present, the effective ways to recycle waste rubber mainly include thermal cracking, production of rubber powder and recycled rubber.

[0003] When preparing reclaimed rubber, in order to achieve a better desulfurization effect, it is usually necessary to add a certain amount of rubber regeneration agent and softener, which can not only improve the dispersion of desulfurization aids and increase the degree of desulfurization, but also give the reclaimed rubber good processing performance and mechanical properties. The rubber regeneration agent and softener used in industrial production are used in large quantities and require high temperatures when used. In the rubber regeneration process, toxic gases such as hydrogen sulfide are easily produced, energy consumption is high, and it is easy to cause secondary pollution to the environment. Therefore, the development of efficient, low-energy, and environmentally friendly rubber regeneration methods is of great significance to the green and sustainable development of the rubber industry.

[0004] Biomass materials are an environmentally friendly and renewable resource with advantages such as wide sources and low costs. As a rubber regeneration aid, it has broad development prospects. Chinese patent (201310520934.3 Waste tire rubber powder regeneration pretreatment process) discloses a waste tire rubber powder regeneration pretreatment process. Before the waste tire rubber powder is regenerated, it is soaked in 75% ethanol for 2 hours, dried at room temperature, sterilized and detoxified, and then allicin is used as a chain extender and Tween 80 as a phase transfer agent to treat the detoxified waste tire rubber powder, which improves the recovery rate of waste tire rubber powder and reduces human labor. However, this method takes a long time and has low efficiency. It is impossible to directly obtain desulfurized rubber powder, and a post-processing process is required. A Chinese patent (201810578050.6 A waste rubber regeneration process and preparation method thereof) discloses a waste rubber regeneration process and a preparation method thereof. By controlling the mass ratio of vegetable oil to vegetable fat and vegetable oil to lignin, the prepared regenerated rubber has excellent physical and mechanical properties and processing properties. However, this method takes a long time to prepare and has many steps, making it difficult to achieve industrial production.

[0005] In order to solve the above problems, it is necessary to provide a more green, energy-saving and environmentally friendly waste rubber recycling process. Summary of the invention

[0006] The invention provides a novel method for preparing green and environmentally friendly recycled rubber, which uses biomass raw materials to complete the depolymerization and regeneration of rubber, so as to solve the technical problems of high energy consumption and environmental pollution of recycled rubber in the prior art.

[0007] The method for preparing green and environmentally friendly recycled rubber according to the embodiment of the present invention comprises the following steps:

[0008] In the first step, waste rubber powder, biomass A and biomass B are put into the first stirring and mixing device, and the materials are discharged after the temperature rises to the set temperature. After being sent to the second stirring and mixing device, they are stirred under the condition of inert gas atmosphere, and the materials are discharged after the temperature rises to the set temperature.

[0009] In the second step, the material discharged in the first step is sent to the first twin-screw extruder through a continuous closed conveying device, the temperature of the screw extruder is controlled at 100° C.-160° C., and the depolymerization reaction is completed within 3 minutes-7 minutes; then it enters the second screw extruder through a continuous closed conveying device, the temperature of the second screw extruder is controlled at 5-25° C., cooled for 2-5 minutes, and then the impurities are removed by a filtering device, and the sheet is thinned through a double-roll refiner to obtain a green and environmentally friendly recycled rubber compound;

[0010] The waste rubber powder includes: any one or more combinations of waste tire full tire rubber powder and waste tire tread rubber powder; wherein the mesh number of the waste rubber powder is 20-80 meshes;

[0011] The biomass A comprises: any one or more combinations of garlic juice and lemon peel juice;

[0012] The biomass B includes any one or more combinations of soybean oil, castor oil, rapeseed oil, palm oil, rapeseed oil residue, soybean oil residue, and palm oil residue.

[0013] The method for preparing green and environmentally friendly recycled rubber as described above, wherein the mass ratio of the waste rubber powder, biomass A, and biomass B is 100:2-6:3-8. .

[0014] In the method for preparing green and environmentally friendly recycled rubber as described above, the temperature of the first stirring and mixing device is set at 60-90° C. and the stirring time is 2-5 min.

[0015] In the method for preparing green and environmentally friendly recycled rubber as described above, the temperature of the second stirring and mixing device is set to 80-110° C., and the stirring time is 3-6 minutes.

[0016] The method for preparing green and environmentally friendly recycled rubber as described above, wherein the first twin-screw extruder has a heating section, a shearing section and a cooling section; wherein the temperature of the heating section is 110°C-130°C, the temperature of the shearing section is 130°C-160°C, and the temperature of the cooling section is 100°C-120°C; and the aspect ratio of the screw of the first twin-screw extruder is 36-56:1.

[0017] In the method for preparing green and environmentally friendly recycled rubber as described above, the second screw extruder is a single-screw extruder or a twin-screw extruder, and the aspect ratio of the screw of the second screw extruder is 28 to 44:1.

[0018] In the method for preparing the green and environmentally friendly recycled rubber as described above, the mesh number of the filtering device is 80 to 120 meshes.

[0019] The present invention uses vegetable oil as a rubber regeneration aid, and can obtain regenerated rubber with a high degree of regeneration. Due to the chemical structure of the vegetable oil itself, it has a long and flexible high-grade fatty acid chain, which is easier to penetrate into the three-dimensional cross-linked network of the rubber powder during the regeneration process, so that the rubber powder is fully swollen, and at the same time helps the rubber regeneration agent to disperse into the cross-linked network of the rubber powder, and then obtains the regenerated rubber with a good depolymerization effect under conditions such as mechanical shearing. Using garlic juice or lemon peel juice as a regeneration aid can utilize a chemical substitution reaction to crack the sulfur cross-linking bonds in the vulcanized rubber, which can reduce the damage of oxidation to the main chain of the rubber molecule. At a lower temperature, combined with the high shear of the screw, the rubber material has plasticity and maintains good physical properties. In the process of rubber regeneration, no harmful gases such as hydrogen sulfide are generated, reducing pollution to the environment.

[0020] Since the selected biomass additives are all in liquid state at room temperature, they can be mixed with rubber powder without an additional heating device. Two stirring and mixing devices are used in combination. On the one hand, the rubber powder and the additives are evenly dispersed. On the other hand, the rubber powder particles and the rubber powder and the stirring and mixing devices generate heat due to self-friction, so that the material is heated up, and the waste rubber powder can be preliminarily depolymerized. The role of introducing inert gas is to promote the movement between the rubber powder particles, isolate oxygen and take away the generated waste gas. When the preliminarily depolymerized material enters the screw extruder, high temperature is not required. The final desulfurization can be achieved mainly by using the strong shearing effect of the screw, and the overall energy consumption is low. In addition, the low desulfurization temperature also meets the requirements of the selected softener and rubber regenerator. The two are easy to volatilize and decompose at a high regeneration temperature, thereby bringing impurities to the product. The low desulfurization temperature ensures both the desulfurization effect and the quality of the product.

[0021] The present invention selects plant-based rubber regeneration agents and softeners with low depolymerization temperature. No unpleasant odor is generated during the depolymerization and regeneration process of waste rubber powder. The regeneration process technology combining mechanical depolymerization with chemical depolymerization is adopted to make the depolymerization degree of waste rubber powder more uniform and reduce the occurrence of "cooked" conditions. The final rubber material can be used for subsequent processes such as vulcanization to prepare some products with high requirements on odor, etc., and can also be used as a filler and added to other rubber formulas to reduce the amount of additives in the rubber formula and reduce the raw material cost and energy consumption cost of production. DETAILED DESCRIPTION

[0022] The preparation method of the green and environmentally friendly recycled rubber described in the present invention can be made of the following materials and components, but is not limited to the following materials and components, for example: waste rubber powder, garlic juice, lemon peel juice, soybean oil, castor oil, rapeseed oil, palm oil, rapeseed oil bottoms, soybean oil bottoms, palm oil bottoms, etc.

[0023] The method for preparing green and environmentally friendly recycled rubber according to the embodiment of the present invention comprises the following steps:

[0024] In the first step, waste rubber powder, biomass A and biomass B are placed in a first stirring and mixing device, and the materials are discharged after the temperature rises to a set temperature. After being sent to a second stirring and mixing device, they are stirred under an inert gas (inert gas includes one of nitrogen, argon and helium) atmosphere, and the materials are discharged after the temperature rises to a set temperature.

[0025] In the second step, the material discharged in the first step is sent to the first twin-screw extruder through a continuous closed conveying device (the closed conveying device is used to prevent the rubber compound from being oxidized), the temperature of the screw extruder is controlled at 100°C-160°C, and the depolymerization reaction is completed within 3min-7min (garlic juice or lemon peel juice is selected as a regeneration aid, which can use a chemical substitution reaction to crack the sulfur cross-linking bonds in the vulcanized rubber, which can reduce the damage of oxidation to the main chain of the rubber molecule. At a lower temperature, combined with the high shear of the screw, the rubber compound has plasticity and maintains good physical properties); then it enters the second screw extruder through a continuous closed conveying device, the temperature of the second screw extruder is controlled at 5-25°C, cooled for 2-5min, and then the impurities are removed by a filtering device, and the sheet is thinned through a double-roll refiner to obtain a green and environmentally friendly recycled rubber compound;

[0026] The waste rubber powder includes: any one or more combinations of waste tire full tire rubber powder and waste tire tread rubber powder; wherein the mesh number of the waste rubber powder is 20-80 meshes;

[0027] The biomass A comprises: any one or more combinations of garlic juice and lemon peel juice;

[0028] The biomass B includes any one or more combinations of soybean oil, castor oil, rapeseed oil, palm oil, rapeseed oil residue, soybean oil residue, and palm oil residue.

[0029] Wherein, the mass ratio of the waste rubber powder, biomass A and biomass B is 100:(2-6):(3-8).

[0030] The first stirring and mixing device has a set temperature of 60-90°C and a stirring time of 2-5 minutes.

[0031] The second stirring and mixing device has a set temperature of 83-110°C and a stirring time of 3-6 minutes.

[0032] The first twin-screw extruder has a heating section, a shearing section and a cooling section; the heating section temperature is 110°C-130°C, the shearing section temperature is 130°C-160°C, and the cooling section temperature is 100°C-120°C; the aspect ratio of the screw of the first twin-screw extruder is (36-56): 1. Under the above temperature conditions, the chemical substitution of the cross-linking bond by the regeneration additive can be achieved, and the breakage of the main chain can be reduced, thereby ensuring the mechanical properties of the regenerated rubber.

[0033] The second screw extruder is a single screw extruder or a twin screw extruder, and the aspect ratio of the screw of the second screw extruder is 28 to 44: 1. The aspect ratio of the screw is controlled within this range so that the rubber material can be fully cooled.

[0034] Wherein, the mesh number of the filtering device is 80 to 120 meshes.

[0035] First embodiment:

[0036] 20-mesh waste tire rubber powder, garlic juice and soybean oil are put into the first stirring and mixing device in a mass ratio of 100:2:4, the temperature is set to 60-65°C, and the material is discharged after stirring for 3 minutes. The material is sent to the second stirring and mixing device, the temperature is set to 83-88°C, and the material is discharged after stirring for 4 minutes under a nitrogen atmosphere. The material is sent to the first screw extruder through a continuous closed conveying device, and the temperature of the heating section of the screw extruder is controlled at 110°C, the temperature of the shear section is controlled at 134°C, and the temperature of the cooling section is controlled at 100°C. The depolymerization reaction is completed within 5 minutes, and then the material enters the second screw extruder through a continuous closed conveying device, and the temperature of the second screw extruder is controlled at 7°C. The material is cooled for 2 minutes, and then the impurities are removed by a filtering device with a mesh number of 80, and the sheet is thinly passed through a double-roll refiner to obtain a green and environmentally friendly recycled rubber compound.

[0037] Second embodiment:

[0038] 30-mesh waste tire rubber powder, garlic juice and rapeseed oil are put into the first stirring and mixing device in a mass ratio of 100:3:5, the temperature is set to 63-68°C, the material is discharged after stirring for 4 minutes, and the material is sent to the second stirring and mixing device, the temperature is set to 84-89°C, the material is discharged after stirring for 4 minutes under a nitrogen atmosphere, and the material is sent to the first screw extruder through a continuous closed conveying device, the temperature of the heating section of the screw extruder is controlled at 117°C, the temperature of the shear section is controlled at 148°C, the temperature of the cooling section is controlled at 100°C, and the depolymerization reaction is completed within 6 minutes. The material is then sent to the second screw extruder through a continuous closed conveying device, the temperature of the second screw extruder is controlled at 15°C, and the material is cooled for 3 minutes. Impurities are removed by a filtering device with a mesh number of 80, and a thin sheet is passed through a double-roll refiner to obtain a green and environmentally friendly recycled rubber compound.

[0039] Third embodiment:

[0040] 60-mesh waste tire rubber powder, lemon peel juice and rapeseed oil are put into the first stirring and mixing device in a mass ratio of 100:5:6, the temperature is set to 67-73°C, the material is discharged after stirring for 2 minutes, and the material is sent to the second stirring and mixing device, the temperature is set to 88-95°C, the material is discharged after stirring for 5 minutes under a nitrogen atmosphere, and the material is sent to the first screw extruder through a continuous closed conveying device, the temperature of the heating section of the screw extruder is controlled at 124°C, the temperature of the shear section is controlled at 160°C, the temperature of the cooling section is controlled at 100°C, the depolymerization reaction is completed within 5 minutes, and then the material enters the second screw extruder through a continuous closed conveying device, the temperature of the second screw extruder is controlled at 10°C, the material is cooled for 2 minutes, and then the impurities are removed by a filtering device with a mesh number of 100, and the sheet is thinly passed through a double-roll refiner to obtain a green and environmentally friendly recycled rubber compound.

[0041] The method for preparing green and environmentally friendly recycled rubber according to the embodiment of the present invention has the following beneficial effects:

[0042] (1) Green and environmentally friendly formula

[0043] Using vegetable oil as a rubber regeneration aid can obtain regenerated rubber with a high degree of regeneration. Due to the chemical structure of vegetable oil itself, it has a long and flexible high-grade fatty acid chain, which is easier to penetrate into the three-dimensional cross-linked network of rubber powder during the regeneration process, so that the rubber powder can fully swell, and at the same time, it helps the rubber regeneration agent to disperse into the cross-linked network of rubber powder, and then obtain regenerated rubber with good depolymerization effect under conditions such as mechanical shearing. Using garlic juice or lemon peel juice as a regeneration aid can use chemical substitution reaction to crack the sulfur cross-linking bonds in vulcanized rubber, which can reduce the damage of oxidation to the main chain of rubber molecules. At a lower temperature, combined with the high shear of the screw, the rubber has plasticity and maintains good physical properties. In the process of rubber regeneration, no harmful gases such as hydrogen sulfide will be produced, reducing pollution to the environment.

[0044] (2) Environmentally friendly and low-carbon process

[0045] Since the selected biomass additives are all in liquid form at room temperature, they can be mixed with rubber powder without additional heating devices. Two stirring and mixing devices are used in combination. On the one hand, the rubber powder and the additives are evenly dispersed. On the other hand, the rubber powder particles and the rubber powder and the stirring and mixing devices generate heat due to self-friction, which increases the temperature of the material and allows the waste rubber powder to be initially depolymerized. The role of the inert gas is to promote the movement between the rubber powder particles, isolate oxygen and take away the waste gas. When the initially depolymerized material enters the screw extruder, it does not require a high temperature. The final desulfurization can be achieved mainly by the strong shearing effect of the screw, and the overall energy consumption is low. In addition, the low desulfurization temperature also meets the requirements of the selected softener and rubber regenerator. The two are easy to volatilize and decompose at high regeneration temperatures, thereby bringing impurities to the product. The low desulfurization temperature ensures both the desulfurization effect and the quality of the product.

[0046] (3) Good product quality

[0047] Plant-based rubber regeneration agents and softeners are selected, with low depolymerization temperature, and no unpleasant odor is produced during the depolymerization and regeneration process of waste rubber powder. The regeneration process technology combining mechanical depolymerization with chemical depolymerization is adopted to make the depolymerization degree of waste rubber powder more uniform and reduce the occurrence of "cooked" conditions. The final rubber compound can be used for subsequent processes such as vulcanization to prepare some products with high requirements on odor, etc., and can also be used as a filler and added to other rubber formulas to reduce the amount of additives in the rubber formula and reduce the cost of raw materials and energy consumption in production.

[0048] The serial numbers of the above embodiments of the present invention are for description only and do not represent the advantages and disadvantages of the embodiments. Through the description of the above implementation methods, those skilled in the art can clearly understand that the above embodiment methods can be implemented by means of some deformations plus the necessary general technology superposition; of course, they can also be implemented by simplifying some important technical features. Based on this understanding, the technical solution of the present invention is essentially or contributes to the prior art in the following aspects: the overall structure and connection method, and the structure described in each embodiment of the present invention.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing green and environmentally friendly recycled rubber, It is characterized in that The steps include: In the first step, waste rubber powder, biomass A and biomass B are put into the first stirring and mixing device, and the materials are discharged after the temperature rises to the set temperature. After being sent to the second stirring and mixing device, they are stirred under the condition of inert gas atmosphere, and the materials are discharged after the temperature rises to the set temperature. In the second step, the material discharged in the first step is sent to the first twin-screw extruder through a continuous closed conveying device, the temperature of the screw extruder is controlled at 100° C.-160° C., and the depolymerization reaction is completed within 3 minutes-7 minutes; then it enters the second screw extruder through a continuous closed conveying device, the temperature of the second screw extruder is controlled at 5-25° C., cooled for 2-5 minutes, and then the impurities are removed by a filtering device, and the sheet is thinned through a double-roll refiner to obtain a green and environmentally friendly recycled rubber compound; The waste rubber powder includes: any one or more combinations of waste tire full tire rubber powder and waste tire tread rubber powder; wherein the mesh number of the waste rubber powder is 20-80 meshes; The biomass A comprises: any one or more combinations of garlic juice and lemon peel juice; The biomass B includes any one or more combinations of soybean oil, castor oil, rapeseed oil, palm oil, rapeseed oil residue, soybean oil residue, and palm oil residue.

2. The method for preparing green and environmentally friendly recycled rubber according to claim 1, It is characterized in that The mass ratio of the waste rubber powder, biomass A and biomass B is 100:2-6:3-8.

3. The method for preparing green and environmentally friendly recycled rubber according to claim 1, It is characterized in that The first stirring and mixing device is set at a temperature of 60-90°C and a stirring time of 2-5 minutes.

4. The method for preparing green and environmentally friendly recycled rubber according to claim 1, It is characterized in that The second stirring and mixing device has a set temperature of 80-110°C and a stirring time of 3-6 minutes.

5. The method for preparing green and environmentally friendly recycled rubber according to claim 1, It is characterized in that The first twin-screw extruder has a heating section, a shearing section and a cooling section; wherein the temperature of the heating section is 110°C-130°C, the temperature of the shearing section is 130°C-160°C, and the temperature of the cooling section is 100°C-120°C; the aspect ratio of the screw of the first twin-screw extruder is 36-56:

1.

6. The method for preparing green and environmentally friendly recycled rubber according to claim 1, It is characterized in that The second screw extruder is a single screw extruder or a twin screw extruder, and the aspect ratio of the screw of the second screw extruder is 28-44:

1.

7. The method for preparing green and environmentally friendly recycled rubber according to claim 1, It is characterized in that The mesh number of the filtering device is 80 to 120 meshes.