Preparation method of low-odor ethylene-propylene-diene monomer regenerated rubber

Abstract

The invention provides a preparation method of low-odor ethylene-propylene-diene monomer regenerated rubber, and belongs to the field of rubber production and manufacturing. Aiming at the characteristic of good sealing effect of the ethylene propylene diene monomer, different schemes are selected in the working procedures of different stages to remove odor. In the two-stage water soaking treatment, the temperature and the soaking time mentioned in the invention are selected according to the source and the type of the odor, so that the odor of the ethylene propylene diene monomer is fully volatilized and dissolved in water, and the optimal odor removal effect is achieved; in the single-screw extruder, primary mixing of materials and water is realized in the compression section, and water vapor and peculiar smell are brought out by heating in the homogenization section, so that the smell removal effect is realized.

Description

Technical Field

[0001] The invention relates to a regenerated rubber manufacturing technology, in particular to a method for preparing low-odor EPDM regenerated rubber, and belongs to the technical field of regenerated rubber production and manufacturing. Background Art

[0002] Since EPDM has excellent sealing, weather resistance, ozone resistance, and aging resistance, its downstream applications are very extensive, such as automotive sealing strips, heat-resistant hoses, cable sheaths and other products. Among them, the main raw material for the manufacture of automotive sealing strips is EPDM, which effectively improves the sealing and waterproof performance of automobiles and occupies more than 80% of the automotive sealing strip market. In cable sheath products, the excellent performance of EPDM ensures the reliability and stability of electronic products in various environments. In heat-resistant hoses, the good heat resistance and aging resistance of EPDM ensure the stable and long-term effective transportation of the liquid in the hose, making it the primary raw material for the production of hoses.

[0003] With the development of the economy and society, the demands of various industries have increased, and the overall amount of waste automobile sealing strips, waste heat-resistant hoses, and waste cable sheaths has also increased rapidly, while the recycling rate is low. Therefore, finding an effective way to recycle and reuse waste EPDM products can not only solve the problem of EPDM rubber resource shortage, but also reduce corporate costs and reduce environmental pollution.

[0004] Due to the diversity of locations and methods of use of EPDM rubber products, it is necessary to strictly ensure that their odor meets standards. Therefore, in order to make waste EPDM products into recycled rubber and utilize them in a diversified manner, it is necessary to study and limit the odor.

[0005] At present, there are few patents targeting the odor of EPDM reclaimed rubber. CN202311857334.6 A low-odor EPDM reclaimed rubber and its preparation method proposes a method of using three screw extruders and adding a deodorant in a closed oxygen-proof environment to obtain a low-odor EPDM reclaimed rubber. The EPDM rubber powder is fed into the first screw extruder through a continuous feeding device, the temperature is controlled at 160-280°C, and a deodorant is added to the cooling section of the screw. The decrosslinking is completed within 4-8 minutes, and then the rubber is fed into the second screw extruder through a continuous closed device, the temperature is controlled at 60-110°C, cooled for 2-5 minutes, and then entered into a three-screw extruder through a continuous closed device, refined for 2-5 minutes, and then thinly passed through a filtering device and a double-roll refining machine to obtain a low-odor EPDM reclaimed rubber.

[0006] However, due to the good sealing properties of EPDM rubber itself, it is often used as a sealing strip, so it is difficult to extract the internal odor through vacuum extraction, and there is a possibility that the effective substances will be extracted; at the same time, the introduced deodorant, especially the reactive deodorant, is a foreign matter introduced into the EPDM rubber itself, and the dosage is difficult to control. If the dosage is small, the deodorization effect is not good, and if the dosage is large, there will be residues, which will affect the formula production when used downstream.

[0007] Therefore, the prior art is in urgent need of a new method for preparing low-odor EPDM recycled rubber. Summary of the invention

[0008] The invention provides a novel preparation method of low-odor EPDM recycled rubber. Different schemes are selected in different stages of the process to remove odor, so that the odor can be removed to the maximum extent, so as to solve the technical problem that the low-odor EPDM recycled rubber is difficult to produce in the prior art.

[0009] The method for preparing low-odor EPDM regenerated rubber according to the embodiment of the present invention comprises the following steps:

[0010] In the first step, the waste EPDM rubber is classified, cleaned and dried, and then put into a crushing device for crushing and removing impurities to obtain EPDM rubber powder;

[0011] The second step is to convey the EPDM rubber powder to the first screw extruder through a continuous feeding device, control the temperature at 235-390° C., and complete the de-crosslinking of the EPDM rubber powder within 6-10 minutes;

[0012] In the third step, the de-crosslinked material is sent to the first water soaking treatment device through a continuous conveying device, and the water soaked material enters the second screw extruder through the continuous conveying device to complete the extraction of water vapor and waste gas;

[0013] In the fourth step, the material after the water vapor and waste gas are extracted in the third step is sent to the refining device through a continuous conveying device; the material output from the refining device is sent to the second water immersion treatment device again, and the treated material is sent to the drying and cooling device through the conveying device to obtain low-odor EPDM recycled rubber.

[0014] The method for preparing low-odor EPDM recycled rubber as described above, wherein the particle size of the EPDM rubber powder is between 1 mm and 10 mm.

[0015] The method for preparing low-odor EPDM recycled rubber as described above, wherein the first screw extruder is a co-rotating twin-screw extruder, the heating section temperature is 295-355°C, the shear section temperature is 345-390°C, and the cooling section temperature is 235-295°C; and the barrel side of the first screw extruder is provided with an exhaust hole.

[0016] In the method for preparing low-odor EPDM regenerated rubber as described above, the temperature of the first water immersion treatment device is 50-90° C., and the water immersion treatment time is 3-8 minutes.

[0017] The method for preparing low-odor EPDM recycled rubber as described above, wherein the second screw extruder is a single screw extruder, and the aspect ratio of the screw is 16 to 36:1; the temperature of the compression section of the second screw extruder is 60 to 85°C, and the temperature of the homogenization section is 120 to 140°C; exhaust ports are provided on both sides of the barrel of the second screw extruder.

[0018] The method for preparing low-odor EPDM recycled rubber as described above, wherein the refining device is a double-roll refining machine, the sheet thickness is 0.1mm-0.7mm, and the roller temperature is 75-85°C.

[0019] The method for preparing low-odor EPDM recycled rubber as described above, wherein the water immersion treatment time of the second water immersion treatment device is 3 to 7 minutes and the temperature is 75 to 100°C.

[0020] The method for preparing low-odor EPDM recycled rubber as described above, wherein the drying and cooling device includes a drying section and a cooling section; the drying method is hot air drying, the drying section temperature is 70-90°C, the cooling section temperature is 20-40°C, and the drying cooling time is 5-10 minutes.

[0021] The present invention also provides a low-odor EPDM regenerated rubber, which is prepared by the method for preparing the low-odor EPDM regenerated rubber.

[0022] The EPDM recycled rubber produced by the present invention has less odor and a wider range of applications. In view of the good sealing effect of EPDM rubber, the present invention selects different schemes for deodorization in different stages of the process. In the two-stage water immersion treatment, the temperature and immersion time mentioned in the present invention are selected according to the source and type of the odor so that the odor of the EPDM rubber can be fully volatilized and dissolved in the water, thereby achieving the best deodorization effect; in the single-screw extruder, the deodorization effect is achieved by achieving preliminary mixing of the material and water in the compression section and raising the temperature in the homogenization section to bring out the water vapor together with the odor. The combination of multiple schemes and equipment ensures that the water content in the product does not exceed the standard while maximizing the deodorization effect.

[0023] In the present invention, the performance of the regenerated rubber after water immersion treatment is improved. The method of the present invention is a physical method, and no additives that may cause changes in material properties are added during the desulfurization stage, and there is no need to worry about the amount of the added additives affecting product application.

[0024] In the present invention, the preferred sample thickness is between 0.2 mm and 0.5 mm. This thickness range achieves a balance between product deodorization effect, product fineness and product output. While ensuring the deodorization effect, the production efficiency is not reduced compared with before. DETAILED DESCRIPTION

[0025] The method for preparing the low-odor EPDM recycled rubber of the present invention can be made of the following materials and components, but is not limited to the following materials and components, for example: EPDM rubber powder, screw extruder, dryer, cooling equipment, etc.

[0026] The method for preparing low-odor EPDM regenerated rubber according to the embodiment of the present invention comprises the following steps:

[0027] In the first step, the waste EPDM rubber is classified, cleaned and dried, and then put into a crushing device for crushing and removing impurities to obtain EPDM rubber powder; the particle size of the EPDM rubber powder is between 1 mm and 10 mm.

[0028] In the second step, the EPDM rubber powder is conveyed to the first screw extruder through a continuous feeding device, the temperature is controlled at 235-390°C, and the de-crosslinking of the EPDM rubber powder is completed within 6-10 minutes; the first screw extruder is a co-rotating twin-screw extruder, the heating section temperature is 295-355°C, the shear section temperature is 345-390°C, and the cooling section temperature is 235-295°C; the first screw extruder is provided with exhaust holes on the side of the barrel.

[0029] In the third step, the de-crosslinked material is sent to the first water immersion treatment device through a continuous conveying device. The material after water immersion treatment enters the second screw extruder through the continuous conveying device to complete the extraction of water vapor and waste gas; the temperature of the first water immersion treatment device is 50-90°C, and the water immersion treatment time is 3-8min.

[0030] The second screw extruder is a single screw extruder, and the aspect ratio of the screw is 16 to 36:1; the temperature of the compression section of the second screw extruder is 60 to 85°C, and the temperature of the homogenization section is 120 to 140°C; exhaust ports are arranged on both sides of the barrel of the second screw extruder.

[0031] In the fourth step, the material after the water vapor and exhaust gas are extracted in the third step is sent to the refining device through a continuous conveying device; the refining device is a double-roller refining machine, the sheet thickness is 0.1mm-0.7mm, and the roller temperature is 75-85°C. The material output from the refining device is sent to the second water immersion treatment device again, and the treated material is sent to the drying and cooling device through the conveying device to obtain low-odor EPDM recycled rubber. The water immersion treatment time of the second water immersion treatment device is 3-7 minutes, and the temperature is 75-100°C.

[0032] The drying and cooling device comprises a drying section and a cooling section; the drying method is hot air drying, the drying section temperature is 70-90°C, the cooling section temperature is 20-40°C, and the drying and cooling time is 5-10 minutes.

[0033] This embodiment also provides a low-odor EPDM regenerated rubber, which is prepared by the preparation method of the low-odor EPDM regenerated rubber of the above embodiment.

[0034] The EPDM recycled rubber produced by the present invention has less odor and a wider range of applications. In view of the good sealing effect of EPDM rubber, the present invention selects different schemes for deodorization in different stages of the process. In the two-stage water immersion treatment, the temperature and immersion time mentioned in the present invention are selected according to the source and type of the odor so that the odor of the EPDM rubber can be fully volatilized and dissolved in the water, thereby achieving the best deodorization effect; in the single-screw extruder, the deodorization effect is achieved by achieving preliminary mixing of the material and water in the compression section and raising the temperature in the homogenization section to bring out the water vapor together with the odor. The combination of multiple schemes and equipment ensures that the water content in the product does not exceed the standard while maximizing the deodorization effect.

[0035] In the present invention, the performance of the regenerated rubber after water immersion treatment is improved. The method of the present invention is a physical method, and no additives that may cause changes in material properties are added during the desulfurization stage, and there is no need to worry about the amount of the added additives affecting product application.

[0036] In the present invention, the preferred sample thickness is between 0.2mm and 0.5mm. This thickness range achieves a balance between the product deodorization effect, product fineness and product output. While ensuring the deodorization effect, the production efficiency is not reduced compared with the previous one. Based on the understanding of the sealing of EPDM rubber, the present invention analyzes the source and type of the odor of waste EPDM rubber, makes full use of the existing technical equipment in the industry, and adopts two water soaking treatments for the two processes of desulfurization and refining to remove the odor in the material to the greatest extent. In the first water soaking treatment process, the desulfurized rubber is directly sent into the water through a conveying device, which can not only reduce the temperature of the rubber, but also reduce the energy consumption of water heating. In the single-screw extruder, the odor is adsorbed and taken out by the water vapor during the degassing process. In the second water soaking treatment process, the water temperature used is 85℃~100℃, which can remove the odor in the product to the greatest extent; the final drying and cooling process further takes away the odor of the product. The EPDM recycled rubber prepared by the method of the present invention has lower odor, wider application range and higher added value, and the whole preparation process has the advantages of simple operation, continuous production and less harm.

[0037] Example 1

[0038] The waste sealing strips were crushed by a crushing device, screened by a screening device in the machine and impurities were removed to obtain EPDM rubber powder with a particle size of 3 mm, and the EPDM rubber powder was fed into the first twin-screw extruder through a continuous feeding device, with a heating section temperature of 325°C, a shear section temperature of 365°C, and a cooling section temperature of 245°C. The de-crosslinking of the EPDM rubber powder was completed within 6 minutes to obtain a material with a Mooney viscosity value ML (1+4) of 69 at 100°C; then the material was fed into the first water immersion treatment device through a continuous conveying device, with a water temperature of 70°C. After 6 minutes, it was conveyed to the second single-screw extruder through a continuous conveying device, with a compression section temperature of 70°C, a homogenization section temperature of 12 5℃, time 8min, get the material with Mooney viscosity value ML(1+4)100℃ of 62; then send the material to the double-roll refiner through the conveying device to thin out the sheet, pass the roller 4 times, the roller temperature is 75℃, the roller distance is 0.1mm, the refining time is 2min, the sheet thickness is 0.17mm, and the material with Mooney viscosity value ML(1+4)100℃ of 53 is obtained; then send the material to the second water immersion treatment device through the conveying device, the temperature is 87℃, the time is 7min; the water-immersed material is sent to the drying and cooling device through the conveying device, the drying section temperature is 80℃, the cooling section temperature is 30℃, the time is 7min, and finally low-odor EPDM recycled rubber is obtained.

[0039] Example 2

[0040] The waste cable sheath is crushed by a crushing device, sieved by a screening device in the machine and impurities are removed to obtain EPDM rubber powder with a particle size of 5 mm, and the EPDM rubber powder is fed into the first twin-screw extruder through a continuous feeding device, the heating section temperature is 335°C, the shear section temperature is 375°C, the cooling section temperature is 255°C, and the de-crosslinking of the EPDM rubber powder is completed within 8 minutes to obtain a material with a Mooney viscosity value ML (1+4) of 58 at 100°C; then it is fed into the first water immersion treatment device through a continuous conveying device, the water temperature is 83°C, and after 5 minutes, it is conveyed to the second single-screw extruder through a continuous conveying device, the compression section temperature is 75°C, the homogenization section temperature is 13 0℃, time 7min, get the material with Mooney viscosity value ML(1+4)100℃ of 53; then send the material to the double-roll refiner through the conveying device to thin out the sheet, pass the roller 4 times, the roller temperature is 78℃, the roller distance is 0.3mm, the refining time is 2min, the sheet thickness is 0.36mm, and the material with Mooney viscosity value ML(1+4)100℃ of 42 is obtained; then send the material to the second water immersion treatment device through the conveying device, the temperature is 93℃, the time is 5min; the water-immersed material is sent to the drying and cooling device through the conveying device, the drying section temperature is 75℃, the cooling section temperature is 25℃, the time is 5min, and finally low-odor EPDM recycled rubber is obtained.

[0041] Example 3

[0042] The waste heat-resistant rubber hose was crushed by a crushing device, screened by a screening device in the machine and impurities were removed to obtain EPDM rubber powder with a particle size of 7 mm, and the EPDM rubber powder was fed into the first twin-screw extruder through a continuous feeding device, with a heating section temperature of 345°C, a shear section temperature of 385°C, and a cooling section temperature of 265°C. The de-crosslinking of the EPDM rubber powder was completed within 7 minutes to obtain a material with a Mooney viscosity value ML (1+4) of 49 at 100°C; then it was fed into the first water immersion treatment device through a continuous conveying device, with a water temperature of 87°C, and after 3 minutes, it was transported to the second single-screw extruder through a continuous conveying device, with a compression section temperature of 65°C, a homogenization section temperature of 12 0℃, time 8min, get the material with Mooney viscosity value ML(1+4)100℃ of 43; then send the material to the double-roll refiner through the conveying device to thin out the sheet, pass the roller 4 times, the roller temperature is 82℃, the roller distance is 0.5mm, the refining time is 2min, the sheet thickness is 0.56mm, and the material with Mooney viscosity value ML(1+4)100℃ of 37 is obtained; then send the material to the second water immersion treatment device through the conveying device, the temperature is 97℃, the time is 4min; the water-immersed material is sent to the drying and cooling device through the conveying device, the drying section temperature is 70℃, the cooling section temperature is 20℃, the time is 7min, and finally low-odor EPDM recycled rubber is obtained.

[0043] Comparative Example 1

[0044] The waste sealing strips were crushed by a crushing device, screened by a screening device in the machine and impurities were removed to obtain EPDM rubber powder with a particle size of 3 mm. The EPDM rubber powder was fed into the first twin-screw extruder through a continuous feeding device. The heating section temperature was 325°C, the shear section temperature was 365°C, and the cooling section temperature was 245°C. The de-crosslinking of the EPDM rubber powder was completed within 6 minutes to obtain a material with a Mooney viscosity value ML (1+4) of 71 at 100°C. The material was then transported to the second single-screw extruder through a continuous conveying device. The compression section temperature was 70°C and the homogenization The section temperature is 125℃, the time is 8min, and a material with a Mooney viscosity value ML(1+4) of 65 at 100℃ is obtained; the material is then sent to a double-roll refiner through a conveying device to thinly pass the sheet, the rollers are passed 4 times, the roller temperature is 75℃, the roller distance is 0.1mm, the refining time is 2min, the sheet thickness is 0.15mm, and a material with a Mooney viscosity value ML(1+4) of 57 at 100℃ is obtained; the material is then sent to a drying and cooling device through a conveying device, the drying section temperature is 80℃, the cooling section temperature is 30℃, the time is 7min, and EPDM recycled rubber is obtained.

[0045] Comparative Example 2

[0046] The waste cable sheath was crushed by a crushing device, screened by a screening device in the machine and impurities were removed to obtain EPDM rubber powder with a particle size of 5 mm, and the EPDM rubber powder was fed into the first twin-screw extruder through a continuous feeding device. The heating section temperature was 335°C, the shear section temperature was 375°C, and the cooling section temperature was 255°C. The de-crosslinking of the EPDM rubber powder was completed within 8 minutes to obtain a material with a Mooney viscosity value ML (1+4) of 61 at 100°C; then it was transported to the second single-screw extruder through a continuous conveying device, the compression section temperature was 75°C, and the The temperature of the chemical section is 130°C, the time is 7 minutes, and a material with a Mooney viscosity value ML (1+4) of 54 at 100°C is obtained; the material is then sent to a double-roll refiner through a conveying device to thin out a sheet, passed through the rollers 4 times, the roller temperature is 78°C, the roller distance is 0.3mm, the refining time is 2 minutes, the sheet thickness is 0.36mm, and a material with a Mooney viscosity value ML (1+4) of 45 at 100°C is obtained; the material is then sent to a drying and cooling device through a conveying device, the drying section temperature is 75°C, the cooling section temperature is 25°C, the time is 5 minutes, and then EPDM recycled rubber is obtained.

[0047] Comparative Example 3

[0048] The waste heat-resistant rubber hose was crushed by a crushing device, screened by a screening device in the machine and impurities were removed to obtain EPDM rubber powder with a particle size of 7 mm, and the EPDM rubber powder was fed into the first twin-screw extruder through a continuous feeding device. The heating section temperature was 345°C, the shear section temperature was 385°C, and the cooling section temperature was 265°C. The de-crosslinking of the EPDM rubber powder was completed within 7 minutes to obtain a material with a Mooney viscosity value ML (1+4) of 47 at 100°C; then it was transported to the second single-screw extruder through a continuous conveying device, the compression section temperature was 65°C, and the The temperature of the chemical section is 120°C, the time is 8 minutes, and a material with a Mooney viscosity value ML (1+4) of 42 at 100°C is obtained; the material is then sent to a double-roll refiner through a conveying device to thin out a sheet, passed through the rollers 4 times, the roller temperature is 82°C, the roller distance is 0.5mm, the refining time is 2 minutes, the sheet thickness is 0.56mm, and a material with a Mooney viscosity value ML (1+4) of 34 at 100°C is obtained; the material is then sent to a drying and cooling device through a conveying device, the drying section temperature is 70°C, the cooling section temperature is 20°C, the time is 7 minutes, and EPDM recycled rubber is obtained.

[0049] The performance parameters of the EPDM recycled rubber are shown in the following table:

[0050] Performance parameters of EPDM recycled rubber in various embodiments and comparative examples

[0051]

[0052] 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.

[0053] 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 low-odor EPDM recycled rubber, characterized in that: The following steps are involved: In the first step, the waste EPDM rubber is classified, cleaned and dried, and then put into a crushing device for crushing and removing impurities to obtain EPDM rubber powder; The second step is to convey the EPDM rubber powder to the first screw extruder through a continuous feeding device, control the temperature at 235-390° C., and complete the de-crosslinking of the EPDM rubber powder within 6-10 minutes; In the third step, the de-crosslinked material is sent to the first water soaking treatment device through a continuous conveying device, and the water soaked material enters the second screw extruder through the continuous conveying device to complete the extraction of water vapor and waste gas; In the fourth step, the material after the water vapor and waste gas are extracted in the third step is sent to the refining device through a continuous conveying device; the material output from the refining device is sent to the second water immersion treatment device again, and the treated material is sent to the drying and cooling device through the conveying device to obtain low-odor EPDM recycled rubber.

2. The method for preparing low-odor EPDM regenerated rubber according to claim 1, characterized in that: The particle size of the EPDM rubber powder is between 1 mm and 10 mm.

3. The method for preparing low-odor EPDM regenerated rubber according to claim 1, characterized in that: The first screw extruder is a co-rotating twin-screw extruder, the heating section temperature is 295-355°C, the shear section temperature is 345-390°C, and the cooling section temperature is 235-295°C; the first screw extruder has a vent hole on the side of the barrel.

4. The method for preparing low-odor EPDM regenerated rubber according to claim 1, characterized in that: The temperature of the first water immersion treatment device is 50-90° C., and the water immersion treatment time is 3-8 minutes.

5. The method for preparing low-odor EPDM regenerated rubber according to claim 1, characterized in that: The second screw extruder is a single screw extruder, and the aspect ratio of the screw is (16-36):1; the temperature of the compression section of the second screw extruder is 60-85°C, and the temperature of the homogenization section is 120-140°C; exhaust ports are arranged on both sides of the barrel of the second screw extruder.

6. The method for preparing low-odor EPDM regenerated rubber according to claim 1, characterized in that: The refining device is a double-roll refining machine, the sheet thickness is 0.1mm-0.7mm, and the roller temperature is 75-85°C.

7. The method for preparing low-odor EPDM regenerated rubber according to claim 1, characterized in that: The water immersion treatment time of the second water immersion treatment device is 3 to 7 minutes, and the temperature is 75 to 100°C.

8. The method for preparing low-odor EPDM regenerated rubber according to claim 1, characterized in that: The drying and cooling device comprises a drying section and a cooling section; the drying method is hot air drying, the drying section temperature is 70-90°C, the cooling section temperature is 20-40°C, and the drying and cooling time is 5-10 minutes.

9. A low-odor EPDM recycled rubber, characterized in that: The low-odor EPDM regenerated rubber is prepared by the method for preparing the low-odor EPDM regenerated rubber according to any one of claims 1 to 8.

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