Preparation process for producing inner tube grade reclaimed rubber by using waste truck tires

Abstract

The invention relates to a preparation process for producing inner tube grade reclaimed rubber by using waste truck tires. The preparation process comprises the following steps: (1) cutting tires into blocks, screening to remove impurities, crushing and magnetically separating to obtain 40-mesh tire rubber powder; (2) mixing the rubber powder, a softening agent, an activating agent and hard pottery clay to obtain a mixed rubber material; (3) feeding the mixed rubber material into a high-speed stirring desulfurization machine, performing high-mixing shearing self-heat-generation desulfurization, cooling by a closed cooling material-slowing screw, feeding the cooled rubber material to a mixing shearing screw, and performing mixing shearing supplementary desulfurization; (4) conveying and cooling through a closed inclined screw, performing high-speed-ratio refining twice, and filtering; and (5) refining the filtered product for the third time, batching, cooling, inspecting and warehousing. According to the inner tube grade reclaimed rubber disclosed by the invention, the processability, the plasticity and the wettability of a rubber material are ensured by adopting a high-oil-content formula, the prepared reclaimed rubber material is relatively good in Mooney stability, the Mooney viscosity is not higher than 70, the fineness of the rubber material is uniform and fine, no granular sensation exists, and the production requirement of a fine-grade inner tube can be met.

Description

Technical Field

[0001] The invention belongs to the technical field of reclaimed rubber, and in particular relates to a preparation process for producing inner tube-grade reclaimed rubber by utilizing waste truck tires. Background Art

[0002] In many countries around the world, automobile inner tubes are mostly made of butyl rubber. However, my country's butyl rubber production is very low, and the price of imported butyl rubber is relatively high, resulting in too high production costs for automobile inner tubes. For this reason, people are considering using recycled rubber to replace butyl rubber.

[0003] my country is a major country in the production and application of recycled rubber. The domestic recycled rubber industry generally uses a combination of rubber powder and recycled activator, and then goes through desulfurization and refining processes. Due to the differences in the dynamic desulfurization tank, plasticizer desulfurization, screw extrusion desulfurization, refining and other processes used, as well as the different requirements for raw materials used, there are very few recycled rubber production companies that can meet the requirements of fine-grade inner tubes. Summary of the Invention

[0004] The purpose of the present invention is to provide a preparation process for producing inner tube grade reclaimed rubber using waste truck tires. The prepared reclaimed rubber has good Mooney stability, a Mooney viscosity not higher than 70, and a uniform and fine rubber fineness without a grainy feel, which can meet the production needs of fine grade inner tubes.

[0005] The technical solution adopted by the present invention to solve the above problems is: a preparation process for producing inner tube grade reclaimed rubber using waste truck tires, comprising the following steps: (1) Cutting, screening, crushing and magnetic separation of the collected waste steel wire radial tires to obtain 40 mesh tire rubber powder; Among them, the cut rubber blocks need to be screened to remove the mud and sand on the surface of the material to ensure the cleanliness of the raw materials. Because the mud and sand are non-magnetic materials, there is no way to remove them once they enter the production system. When they reach the finished product stage, impurities can easily cause stress defects during vulcanization, affecting the physical and mechanical properties of the rubber.

[0006] The magnetic separation process goes through 7 magnetic separations, specifically: the first magnetic separation is 5-roller linkage steel wire magnetic separation, the second is belt magnetic separation, the third is double-roller magnetic separation, the fourth is 12,000 Gauss magnetic rod (removable), the fourth belt magnetic separation, the fifth is single-roller magnetic separator, the sixth and seventh are both 12,000 Gauss magnetic rods (removable) to remove all magnetic metal impurities in the rubber powder; the filter uses a 40-mesh national standard filter to screen the rubber powder, and the residue on the finished product can reach less than 5%, ensuring that the particles of the rubber powder raw material are fine, which is conducive to the desulfurization of the recycled rubber and the fineness of subsequent processing.

[0007] (2) Mix 40-mesh tire rubber powder, softener, activator, and hard clay at room temperature to obtain a mixed rubber material; (3) The mixed rubber material enters the high-speed stirring desulfurizer for high-mixing shearing autogenous thermal desulfurization, and then is cooled by the closed cooling slow material spiral, and evenly sent to the mixing shear spiral for mixing shearing supplementary desulfurization; (4) After desulfurization, the rubber material is cooled by closed inclined spiral conveyor and then refined twice at a high speed ratio, and then filtered; (5) The filtered product is refined for the third time, sliced, cooled, inspected, and stored.

[0008] The activator is activator 480, and the hard clay is hard clay modified by a silane coupling agent and stearic acid.

[0009] Preferably, the waste steel wire load-bearing radial tire in step (1) is a load-bearing radial tire with a specification of R9.00-12.00, that is, a load-bearing radial tire with a cross-sectional width in the range of 9.00-12.00 (inches), the rubber content of which can reach between 50% and 55%, the ash content is not greater than 8%, and the Mooney content reaches above 9.5 MPa, so that the tensile strength of the recycled rubber can be guaranteed.

[0010] Preferably, the crushing process in step (1) adopts a low-temperature powder crushing process, which is carried out at a temperature not higher than 100 degrees Celsius. This setting avoids high-temperature carbonization of the material, which affects the physical properties and environmental friendliness of the final product.

[0011] Preferably, step (3) is specifically as follows: the mixed rubber material enters a high-speed stirring desulfurizer, is stirred at a high speed of 1400 rpm, and the friction and collision between the rubber powder and the rubber powder and the wall of the stirring bin increase the temperature of the rubber material to 200-230 degrees Celsius for desulfurization, and then is cooled by a closed cooling slow material spiral, and is evenly fed to a mixing shear spiral (the screw is a series-type tool and there is an embedded square tool on the barrel), and the rubber material is sheared and supplemented with desulfurization by the fixed tool, and no additional heating device is used during the desulfurization period.

[0012] Preferably, in step (4), after desulfurization, the rubber material enters a closed jacket cooling conveying screw, and is cooled by spraying water during the process. The cooling time is 15 minutes, so that the rubber material after desulfurization is cooled to below 60 degrees Celsius. At the same time, the water vapor generated during the water spray cooling process can have a certain protective effect on the rubber material, preventing the rubber material from excessively contacting the oxygen in the closed space and reducing the oxidation of the rubber material.

[0013] Preferably, the softener is aromatic oil asphalt with a softening point of 60-70 degrees Celsius.

[0014] Preferably, the mass ratio of 40-mesh tire rubber powder, softener, activator, and hard clay is 100:20-25:0.25-0.4:3-5.

[0015] Preferably, the temperature of the two high-speed ratio refinings is 85-105 degrees Celsius, and the temperature of the three refinings is 85-95 degrees Celsius.

[0016] Preferably, the linear speed ratio of the two rollers in the two high-speed ratio refining is 1.9-2.1.

[0017] Preferably, the hard clay is prepared by the following preparation method: hard clay, silane coupling agent, stearic acid and anhydrous ethanol are uniformly mixed, ball-milled for 4-5 hours, filtered and dried.

[0018] Compared with the prior art, the advantages of the present invention are: (1) The inner tube grade reclaimed rubber of the present invention adopts a high oil content formula to ensure the processability, plasticity and lubricity of the rubber, and at the same time adds some modified hard clay to ensure the performance of the rubber and facilitate the extrusion performance of the rubber. Aromatic oil asphalt is used as a softener and activator 480 is used as a free radical capping agent to facilitate desulfurization. The application of modified hard clay in the inner tube grade reclaimed rubber significantly improves the mechanical properties of the reclaimed rubber.

[0019] (2) In the preparation process of the inner tube grade reclaimed rubber of the present invention, the desulfurization adopts high mixed shear autogenous thermal desulfurization and mixed shear supplementary desulfurization process, which can make the reclaimed rubber have better Mooney stability and fineness, which is beneficial to the extrusion processing of subsequent products.

[0020] (3) In the preparation process of the inner tube grade reclaimed rubber of the present invention, the temperature of the rubber material after desulfurization is relatively high. A rapid cooling process is adopted, and the material is cooled by a closed inclined spiral conveyor. Water spraying is added during the process to cool the material. The final discharge temperature of the finished product is below 45°C, which effectively avoids the oxidation of the rubber material by oxygen due to high temperature. In addition, two high-speed ratio refining processes are used to ensure the fineness of the rubber material and increase the plasticity of the rubber material. DETAILED DESCRIPTION

[0021] The present invention is described in further detail below with reference to the examples. Example 1

[0022] A preparation process for producing inner tube grade reclaimed rubber from waste truck tires comprises the following steps: (1) The collected waste steel wire load-bearing radial tires are cut into pieces, screened to remove impurities, crushed, and magnetically separated to obtain 40-mesh tire rubber powder.

[0023] Among them, the coarsely crushed rubber blocks need to be screened to remove the mud and sand on the surface of the material to ensure the cleanliness of the raw materials. Since the mud and sand are non-magnetic materials, there is no way to remove them once they enter the production system. When they reach the finished product stage, impurities can easily cause stress defects during vulcanization, affecting the physical and mechanical properties of the rubber.

[0024] The magnetic separation process goes through 7 magnetic separations, specifically: the first magnetic separation is 5-roller linkage steel wire magnetic separation, the second is belt magnetic separation, the third is double-roller magnetic separation, the fourth is 12,000 Gauss magnetic rod (removable), the fourth belt magnetic separation, the fifth is single-roller magnetic separator, the sixth and seventh are both 12,000 Gauss magnetic rods (removable) to remove all magnetic metal impurities in the rubber powder; the filter uses a 40-mesh national standard filter to screen the rubber powder, and the residue on the finished product can reach less than 5%, ensuring that the particles of the rubber powder raw material are fine, which is conducive to the desulfurization of the recycled rubber and the fineness of subsequent processing.

[0025] (2) 40-mesh tire rubber powder, softener aromatic oil asphalt with a softening point of 65 degrees Celsius, activator 480, and modified hard clay (20 parts by mass of hard clay, 10 parts by mass of silane coupling agent, 10 parts by mass of stearic acid, and 1 part by mass of anhydrous ethanol were mixed evenly, ball-milled at a speed of 1200 r / min for 5 hours, filtered, and dried to obtain modified hard clay) were mixed evenly at room temperature to obtain a mixed rubber material.

[0026] (3) The mixed rubber material enters the high-speed stirring desulfurizer and is stirred at a high speed of 1400 rpm. The friction and collision between the rubber powder and the rubber powder and the mixing chamber wall increase the temperature to 200-230 degrees Celsius for desulfurization. After that, it is cooled by the closed cooling slow material spiral and evenly sent to the mixing shear spiral (the screw is a series-type tool and there is an embedded square tool on the barrel). The rubber material is sheared and supplemented with desulfurization by the fixed tool. There is no additional heating device during the desulfurization period.

[0027] (4) After desulfurization, the rubber material is cooled by a closed inclined spiral conveyor. Specifically, after discharging, the rubber material enters the jacket cooling spiral in a closed manner. During the process, water is sprayed for cooling. The cooling time is 15 minutes. At the same time, water vapor can have a certain protective effect on the rubber material, preventing the rubber material from excessively contacting the oxygen in the closed space and reducing the oxidation of the rubber material. Then, it is refined twice at a high speed ratio (the linear speed ratio of the two rollers during the two refining processes is 2.1), and then filtered. The filter mesh aperture is 40 mesh. (5) The filtered product is refined three times, sliced, cooled, inspected, and stored.

[0028] In step (1), the waste steel wire load-bearing radial tires are load-bearing tires with a specification of R9.00-12.00, and the coarse and fine crushing processes adopt a low-temperature powder breaking process, both of which are carried out at a temperature of 90 degrees Celsius. Example 2

[0029] A preparation process for producing inner tube grade reclaimed rubber from waste truck tires comprises the following steps: (1) The collected waste steel wire load-bearing radial tires are cut into pieces, screened to remove impurities, crushed, and magnetically separated to obtain 40-mesh tire rubber powder.

[0030] Among them, the coarsely crushed rubber blocks need to be screened to remove the mud and sand on the surface of the material to ensure the cleanliness of the raw materials. Since the mud and sand are non-magnetic materials, there is no way to remove them once they enter the production system. When they reach the finished product stage, impurities can easily cause stress defects during vulcanization, affecting the physical and mechanical properties of the rubber.

[0031] The magnetic separation process goes through 7 magnetic separations, specifically: the first magnetic separation is 5-roller linkage steel wire magnetic separation, the second is belt magnetic separation, the third is double-roller magnetic separation, the fourth is 12,000 Gauss magnetic rod (removable), the fourth belt magnetic separation, the fifth is single-roller magnetic separator, the sixth and seventh are both 12,000 Gauss magnetic rods (removable) to remove all magnetic metal impurities in the rubber powder; the filter uses a 40-mesh national standard filter to screen the rubber powder, and the residue on the finished product can reach less than 5%, ensuring that the particles of the rubber powder raw material are fine, which is conducive to the desulfurization of the recycled rubber and the fineness of subsequent processing.

[0032] (2) 40-mesh tire rubber powder, softener aromatic oil asphalt with a softening point of 65 degrees Celsius, activator 480, and modified hard clay (20 parts by mass of hard clay, 10 parts by mass of silane coupling agent, 10 parts by mass of stearic acid, and 1 part by mass of anhydrous ethanol were mixed evenly, ball-milled at a speed of 1200 r / min for 5 hours, filtered, and dried to obtain modified hard clay) were mixed evenly at room temperature to obtain a mixed rubber material.

[0033] (3) The mixed rubber material enters the high-speed stirring desulfurizer and is stirred at a high speed of 1400 rpm. The friction and collision between the rubber powder and the rubber powder and the mixing chamber wall increase the temperature to 200-230 degrees Celsius for desulfurization. After that, it is cooled by the closed cooling slow material spiral and evenly sent to the mixing shear spiral (the screw is a series-type tool and there is an embedded square tool on the barrel). The rubber material is sheared and supplemented with desulfurization by the fixed tool. There is no additional heating device during the desulfurization period.

[0034] (4) After desulfurization, the rubber material is cooled by a closed inclined spiral conveyor. Specifically, after discharge, the rubber material enters the jacketed cooling spiral in a closed manner and is cooled by spraying water during the process. The cooling time is 15 minutes. At the same time, water vapor can have a certain protective effect on the rubber material, preventing the rubber material from excessively contacting the oxygen in the closed space and reducing the oxidation of the rubber material. Then, two high-speed ratio refining processes are carried out (the linear speed ratio of the two rollers during the two refining processes is 2.0), and then filtration is carried out. The filter mesh aperture is 40 mesh.

[0035] (5) The filtered product is refined three times, sliced, cooled, inspected, and stored.

[0036] In step (1), the waste steel wire load-bearing radial tires are load-bearing tires with a specification of R9.00-12.00; the coarse crushing and fine crushing processes adopt a low-temperature powder breaking process, both of which are carried out at a temperature of 80 degrees Celsius. Example 3

[0037] A preparation process for producing inner tube grade reclaimed rubber from waste truck tires comprises the following steps: (1) Cutting, screening, crushing and magnetic separation of the collected waste steel wire radial tires to obtain 40 mesh tire rubber powder; Among them, the coarsely crushed rubber blocks need to be screened to remove the mud and sand on the surface of the material to ensure the cleanliness of the raw materials. Since the mud and sand are non-magnetic materials, there is no way to remove them once they enter the production system. When they reach the finished product stage, impurities can easily cause stress defects during vulcanization, affecting the physical and mechanical properties of the rubber.

[0038] The magnetic separation process goes through 7 magnetic separations, specifically: the first magnetic separation is 5-roller linkage steel wire magnetic separation, the second is belt magnetic separation, the third is double-roller magnetic separation, the fourth is 12,000 Gauss magnetic rod (removable), the fourth belt magnetic separation, the fifth is single-roller magnetic separator, the sixth and seventh are both 12,000 Gauss magnetic rods (removable) to remove all magnetic metal impurities in the rubber powder; the filter uses a 40-mesh national standard filter to screen the rubber powder, and the residue on the finished product can reach less than 5%, ensuring that the particles of the rubber powder raw material are fine, which is conducive to the desulfurization of the recycled rubber and the fineness of subsequent processing.

[0039] (2) 40-mesh tire rubber powder, softener aromatic oil asphalt with a softening point of 65 degrees Celsius, activator 480, and modified hard clay (20 parts by mass of hard clay, 10 parts by mass of silane coupling agent, 10 parts by mass of stearic acid, and 1 part by mass of anhydrous ethanol are mixed evenly, ball-milled at a speed of 1200 r / min for 5 hours, filtered, and dried to obtain modified hard clay) are mixed evenly at room temperature to obtain a mixed rubber material; (3) The mixed rubber material enters the high-speed stirring desulfurizer and is stirred at a high speed of 1400 rpm. The friction and collision between the rubber powder and the rubber powder and the mixing chamber wall increase the temperature to 200-230 degrees Celsius for desulfurization. After that, it is cooled by the closed cooling slow material spiral and evenly sent to the mixing shear spiral (the screw is a series-type tool and there is an embedded square tool on the barrel). The rubber material is sheared and supplemented with desulfurization by the fixed tool. There is no additional heating device during the desulfurization period.

[0040] (4) After desulfurization, the rubber material is cooled by a closed inclined spiral conveyor. Specifically, after discharge, the rubber material enters the jacketed cooling spiral in a closed manner and is cooled by spraying water during the process. The cooling time is 15 minutes. At the same time, water vapor can have a certain protective effect on the rubber material, preventing the rubber material from excessively contacting the oxygen in the closed space and reducing the oxidation of the rubber material. Then, two high-speed ratio refining processes are carried out (the linear speed ratio of the two rollers during the two refining processes is 1.9), and then filtration is carried out. The filter mesh aperture is 40 mesh.

[0041] (5) The filtered product is refined three times, sliced, cooled, inspected, and stored.

[0042] In step (1), the waste steel wire load-bearing radial tires are load-bearing tires with a specification of R9.00-12.00; the coarse crushing and fine crushing processes adopt a low-temperature powder breaking process, both of which are carried out at a temperature of 85 degrees Celsius.

[0043] Comparative Example 1 The only difference from Example 1 is that the linear speed ratio of the two rollers in the high-speed ratio refining is 1.5.

[0044] Comparative Example 2 The only difference from Example 1 is that the activator is 2,4-p-tert-butylphenol (activator 580).

[0045] Comparative Example 3 The only difference from Example 1 is that the rubber material is naturally cooled after desulfurization in step (4).

[0046] The physical and mechanical properties of the examples and comparative examples were measured according to the national standard (GB / T13460-2016). The performance test results are shown in Table 1:

[0047] In addition to the above embodiments, the present invention also includes other implementation methods. Any technical solutions formed by equivalent transformation or equivalent replacement should fall within the scope of protection of the claims of the present invention.

Claims

1. A preparation process for producing inner tube grade reclaimed rubber from waste truck tires, characterized by: The following steps are involved: (1) Cutting, screening, crushing and magnetic separation of the collected waste steel wire radial tires to obtain 40 mesh tire rubber powder; (2) Mix 40-mesh tire rubber powder, softener, activator, and hard clay at room temperature to obtain a mixed rubber material; (3) Desulfurization of the mixed rubber; (4) After desulfurization, the rubber material is cooled by closed inclined spiral conveyor and then refined twice at a high speed ratio, and then filtered; (5) The filtered product is refined for the third time, unloaded, cooled, inspected, and stored; The activator is activator 480, and the hard clay is hard clay modified by a silane coupling agent and stearic acid.

2. The process for producing inner tube grade reclaimed rubber from waste truck tires according to claim 1, characterized in that: In step (1), the waste steel wire load-bearing radial tires are tires with a load-bearing tire specification of R9.00-12.

00.

3. The process for producing inner tube grade reclaimed rubber from waste truck tires according to claim 1, characterized in that: The crushing process in step (1) adopts a low-temperature powder crushing process and is carried out at a temperature not higher than 100 degrees Celsius.

4. The process for producing inner tube grade reclaimed rubber from waste truck tires according to claim 1, characterized in that: The desulfurization process in step (3) is as follows: the mixed rubber material enters the high-speed stirring desulfurizer for high-mixing shearing autogenous thermal desulfurization, and is then cooled by the closed cooling slow material spiral and evenly sent to the mixing shear spiral for mixing shearing supplementary desulfurization.

5. The process for producing inner tube grade reclaimed rubber from waste truck tires according to claim 1, characterized in that: In step (4), the desulfurized rubber material enters a closed jacket cooling conveying screw and is sprayed with water for cooling during the process. The cooling time is 15 minutes, so that the desulfurized rubber material is cooled to below 60 degrees Celsius.

6. The process for producing inner tube grade reclaimed rubber from waste truck tires according to claim 1, characterized in that: The softener is aromatic oil asphalt.

7. The process for producing inner tube grade reclaimed rubber from waste truck tires according to claim 1, characterized in that: The mass ratio of 40-mesh tire rubber powder, softener, activator and hard clay is 100:20-25:0.25-0.4:3-5.

8. The process for producing inner tube grade reclaimed rubber from waste truck tires according to claim 1, characterized in that: The temperatures of the two high-speed refining steps are both 85-105 degrees Celsius, and the temperature of the three refining steps is 85-95 degrees Celsius.

9. The process for producing inner tube grade reclaimed rubber from waste truck tires according to claim 1, characterized in that: The linear speed ratio of the two rollers in the two high-speed ratio refining is 1.9-2.

1.

10. The process for producing inner tube grade reclaimed rubber from waste truck tires according to claim 1, characterized in that: The hard clay is prepared by the following preparation method: hard clay, silane coupling agent, stearic acid and anhydrous ethanol are uniformly mixed, ball-milled for 4-5 hours, filtered and dried.

Images