Preparation method of high oil-filled liquid regenerated rubber

Abstract

The invention provides a preparation method of high oil-filled liquid regenerated rubber, and belongs to the field of regenerated rubber manufacturing. The method comprises the following steps: mixing and preheating waste rubber powder and a part of softener; feeding the mixed and preheated raw materials into a double-screw or multi-screw extruder for heating and primary decrosslinking; feeding the raw materials subjected to primary de-crosslinking into a parallel co-rotating twin-screw extruder, adding the rest softening agent for multiple times through a plurality of feeding holes in a machine barrel, and extruding to obtain the high oil-filled liquid regenerated rubber. Compared with traditional regenerated rubber, the processing performance is better, the surface of a product is smoother, the production process is low-carbon and environment-friendly, and the additional value of resource utilization of waste rubber is greatly improved.

Description

Technical Field

[0001] The invention relates to rubber synthesis manufacturing technology, in particular to a preparation method of highly oil-filled liquid recycled rubber, belonging to the technical field of recycled rubber manufacturing. Background Art

[0002] Recycled rubber has become the third most widely used type of rubber after natural rubber and synthetic rubber. Since the emergence of recycle rubber, the fineness problem has always affected the scope of use of recycle rubber. The so-called fineness actually reflects the problem of the uniformity of desulfurization of recycle rubber, which mainly includes two aspects: the uniformity of the desulfurization degree of each rubber powder particle on a macro scale, and the plasticity (Mooney viscosity value) directly affects the smoothness of the product. The viscosity is too high and it is not easy to mix and extrude; on the other hand, it is the problem of the uniformity of desulfurization inside and outside the single rubber powder particle, that is, the problem of the "core-shell" structure. Since the traditional method of producing "solid" recycle rubber increases the degree of desulfurization, it will further destroy the rubber hydrocarbons and reduce the mechanical properties of the recycle rubber, so it is difficult to balance the relationship between mechanical properties, fineness and energy consumption in the production process.

[0003] In recent years, with the elimination of high-temperature and high-pressure dynamic desulfurization technology and the rise of continuous atmospheric desulfurization regeneration technology, the fineness problem has increasingly affected the promotion and use of recycled rubber. At the same time, the concept of liquid (low-viscosity) recycled rubber has been proposed in the industry. When recycled rubber is added to products such as tires, it partially replaces raw rubber, carbon black, operating oil and resin, etc., and has little correlation with the mechanical properties of the recycled rubber itself. For example, Zhang Liqun et al. selected a rubber powder particle size of 0.1 to 10 mm in CN102601975B "A method for continuously preparing liquid recycled rubber using a screw extruder". It is believed that the material can be extruded from the screw head to obtain the required recycled rubber, and there is no need for subsequent refining processes, which greatly reduces energy consumption; they did not realize the inevitable presence of raw rubber in the process of rubber powder desulfurization. The Mooney viscosity ML100℃1+4 of the reclaimed rubber particles prepared by Zhang Jianwu et al. in CN201910308916.6 "A low Mooney viscosity reclaimed rubber particles and their preparation method and use" is 15-40, and the sol content is greater than 30%. It is used for waterproofing membranes or road construction, and the fineness of the liquid glue is not required. The particle size is selected to be 10-80 mesh, and the rubber powder is preheated at high temperature using a high-speed mixer, and then discharged into a kneader for kneading and mixing and cooled to below 160℃; then the material is discharged into a screw extruder for mixing through a screw discharge, and further granulated through a die head water pelletizer to obtain low Mooney viscosity reclaimed rubber particles. Under such high temperature conditions, the rubber powder is inevitably subject to thermal oxidation aging.

[0004] For other types of recycled rubber, especially liquid recycled rubber which may also have fineness problems, the prior art urgently needs a new method for preparing highly oil-filled liquid recycled rubber, which can fully replace the functions of raw rubber, carbon black, operating oil and resin, increase the added value of recycled rubber and utilize it as a resource. Summary of the invention

[0005] The invention provides a novel method for preparing highly oil-filled liquid recycled rubber, which can improve the added value of the recycled rubber by adopting new process measures, so as to solve the technical problem that the liquid recycled rubber in the prior art cannot meet the requirements.

[0006] The method for preparing highly oil-filled liquid regenerated rubber according to an embodiment of the present invention comprises the following steps:

[0007] The first step is to mix and preheat the waste rubber powder and part of the softener;

[0008] In the second step, the mixed and preheated raw materials are fed into a twin-screw or multi-screw extruder for heating and preliminary cross-linking.

[0009] In the third step, the raw material after preliminary de-crosslinking is fed into a parallel co-rotating twin-screw extruder, and the remaining softener is added in multiple times through multiple feeding ports on the barrel, and highly oil-filled liquid regenerated rubber is obtained after extrusion;

[0010] The particle size of the waste rubber powder is 20-60 mesh, and the waste rubber powder is the rubber powder obtained by crushing waste tires;

[0011] The mass ratio of the waste rubber powder, part of the softener and the remaining softener is 100:0-10:50-200; the softener is any one or more combinations of pine tar oil, epoxidized soybean oil, cycloalkane oil, paraffin oil and environmentally friendly aromatic oil.

[0012] In the method for preparing highly oil-filled liquid recycled rubber as described above, the mixing preheating in the first step is maintained at 100-130° C. for 5-20 minutes.

[0013] In the method for preparing highly oil-filled liquid recycled rubber as described above, in the second step, the aspect ratio of the screw of the twin-screw or multi-screw extruder is 32:1 to 48:1.

[0014] The method for preparing highly oil-filled liquid recycled rubber as described above, wherein, in the second step, the heating section temperature of the twin-screw or multi-screw extruder is between 150°C and 220°C, the mixing section temperature is between 220°C and 280°C, and the insulation section temperature is between 150°C and 220°C; the heating and preliminary de-crosslinking time is 1-10 min.

[0015] The method for preparing highly oil-filled liquid reclaimed rubber as described above, wherein in the third step, the parallel co-rotating twin-screw extruder has three feeding ports;

[0016] The remaining softener is added through three feeding ports in a mass ratio of 1:(1.3-2.5):(1.5-6) ​​in order; the time interval between additions is not less than 30 seconds.

[0017] The method for preparing highly oil-filled liquid recycled rubber as described above, wherein, in the third step, the parallel co-rotating twin-screw extruder has a feeding and conveying premixing section, a mixing and kneading section and a compression and exhaust section; the temperature of the feeding and conveying premixing section is 80°C to 130°C, the temperature of the mixing and kneading section is 130°C to 180°C, and the temperature of the compression and exhaust section is 130°C to 80°C; the residence time of the raw materials in the third step in the parallel co-rotating twin-screw extruder is 3 to 6 minutes.

[0018] The present invention redesigns the mechanism of de-crosslinking and regeneration of waste rubber. After the waste rubber is moderately de-crosslinked, the damage of rubber hydrocarbons is minimized, and then a high-filling amount of operating oil is added. The principle of similar compatibility is utilized to complete the de-crosslinking reaction while penetrating into the regenerated rubber, thereby evenly destroying the original crosslinking network, so that the original carbon black and additives are fully released. The prepared highly oil-filled liquid regenerated rubber hydrocarbon has a high molecular weight of polymer chain, little damage to the original additives in the waste rubber, and low viscosity. When used downstream, it can replace more raw rubber, carbon black, operating oil and resin, etc. Compared with adding traditional regenerated rubber, the processing performance is better, the surface of the product is smoother, the production process is low-carbon and environmentally friendly, and the added value of the resource utilization of waste rubber is greatly improved.

[0019] The present invention connects the mixing preheating, preliminary de-crosslinking and swelling reaction processes in series, and utilizes the flexible and changeable geometric arrangement of the screw extruder. In the first extruder, under weak shear conditions, the waste rubber powder particles are evenly heated and preliminarily de-crosslinked to obtain rubber particles with loose surfaces. After entering the second extruder, the softener added in batches gradually penetrates, which is more conducive to the subsequent addition of oil products in the process of strengthening heat transfer. Liquid regenerated rubber with high oil filling is obtained through the exhaust effect. The series screw extruder unit of two screw extruders has short time, high efficiency, continuous and automated process, labor saving, and stable and controllable production process. DETAILED DESCRIPTION

[0020] The method for preparing the highly oil-filled liquid recycled rubber of the present invention can be made of the following materials and components, and is not limited to the following materials and components, for example: etc.

[0021] The method for preparing highly oil-filled liquid regenerated rubber according to an embodiment of the present invention comprises the following steps:

[0022] In the first step, the waste rubber powder and part of the softener are mixed and preheated; the mixing and preheating in the first step is maintained at 100-130° C. for 5-20 minutes;

[0023] The mass ratio of the waste rubber powder, part of the softener and the remaining softener is 100:0-10:50-200; the softener is any one or more combinations of pine tar oil, epoxidized soybean oil, cycloalkane oil, paraffin oil and environmentally friendly aromatic oil.

[0024] The second step is to feed the mixed and preheated raw materials into a twin-screw or multi-screw extruder for heating and preliminary cross-linking; wherein the particle size of the waste rubber powder is 20-60 mesh, and the waste rubber powder is the rubber powder obtained by crushing waste tires;

[0025] The aspect ratio of the screw of the twin-screw or multi-screw extruder is 32:1 to 48:1;

[0026] The heating section temperature of the twin-screw or multi-screw extruder is 150° C. to 220° C., the mixing section temperature is 220° C. to 280° C., and the insulation section temperature is 150° C. to 220° C.; the heating and preliminary cross-linking time is 1-10 min.

[0027] In the third step, the raw material after preliminary de-crosslinking is fed into a parallel co-rotating twin-screw extruder, and the remaining softener is added in multiple times through multiple feeding ports on the barrel, and highly oil-filled liquid regenerated rubber is obtained after extrusion;

[0028] The parallel co-rotating twin-screw extruder has three feeding ports; the remaining softener is added through the three feeding ports in a mass ratio of 1:(1.3-2.5):(1.5-6) ​​in order; the time interval between additions is not less than 30 seconds.

[0029] Wherein, in the third step, the parallel co-rotating twin-screw extruder has a feeding and conveying premixing section, a mixing and kneading section and a compression and exhaust section; the temperature of the feeding and conveying premixing section is 80°C to 130°C, the temperature of the mixing and kneading section is 130°C to 180°C, and the temperature of the compression and exhaust section is 130°C to 80°C; the residence time of the raw materials in the third step in the parallel co-rotating twin-screw extruder is 3 to 6 minutes.

[0030] The present invention redesigns the mechanism of de-crosslinking and regeneration of waste rubber. After the waste rubber is moderately de-crosslinked, the damage of rubber hydrocarbons is minimized, and then a high-filling amount of operating oil is added. The principle of similar compatibility is utilized to complete the de-crosslinking reaction while penetrating into the regenerated rubber, thereby evenly destroying the original crosslinking network, so that the original carbon black and additives are fully released. The prepared highly oil-filled liquid regenerated rubber hydrocarbon has a high molecular weight of polymer chain, little damage to the original additives in the waste rubber, and low viscosity. When used downstream, it can replace more raw rubber, carbon black, operating oil, resin, etc. Compared with adding traditional regenerated rubber, the processing performance is better, the surface of the product is smoother, the production process is low-carbon and environmentally friendly, and the added value of the resource utilization of waste rubber is greatly improved.

[0031] The present invention connects the mixing preheating, preliminary de-crosslinking and swelling reaction processes in series, and utilizes the flexible and changeable geometric arrangement of the screw extruder. In the first extruder, under weak shear conditions, the waste rubber powder particles are evenly heated and preliminarily de-crosslinked to obtain rubber particles with loose surfaces. After entering the second extruder, the softener added in batches gradually penetrates, which is more conducive to the subsequent addition of oil products in the process of strengthening heat transfer. Liquid regenerated rubber with high oil filling is obtained through the exhaust effect. The series screw extruder unit of two screw extruders has short time, high efficiency, continuous and automated process, labor saving, and stable and controllable production process.

[0032] Example 1

[0033] 100 phr of 60-mesh waste load-carrying tire rubber powder and 5 phr of environmentally friendly aromatic oil were mixed at 110° C. for 12 minutes, added into a twin-screw extruder with a length-to-diameter ratio of 40:1, reacted for 8 minutes at 180° C. in the heating section, 240° C. in the mixing section and 180° C. in the insulation section, and then continuously fed into a parallel co-rotating twin-screw extruder, added to three feeding ports in sequence at a mass ratio of 1:1.5:5 three times, and the remaining 50 phr of environmentally friendly aromatic oil was added. After mixing for 3 minutes at 80° C. in the heating section, 150° C. in the mixing section and 80° C. in the exhaust section, liquid recycled rubber was obtained.

[0034] Example 2

[0035] 100 phr of 20-mesh waste passenger car rubber powder and 10 phr of cyclohexane oil were mixed at 130° C. for 20 minutes, added into a three-screw extruder with a length-to-diameter ratio of 48:1, reacted for 5 minutes at a heating section of 200° C., a mixing section of 280° C., and a heat preservation section of 200° C., and then continuously fed into a parallel co-rotating twin-screw extruder, and the remaining 100 phr of cyclohexane oil was added to three feeding ports in three times according to a mass ratio of 1:2.5:6. After kneading for 5 minutes at a heating section of 100° C., a mixing section of 180° C., and a venting section of 100° C., liquid recycled rubber was obtained.

[0036] Example 3

[0037] 100 phr of 22-mesh waste load tire top rubber powder was mixed at 130° C. for 5 minutes, added into a twin-screw extruder with a length-to-diameter ratio of 32:1, reacted at 150° C. in the heating section, 260° C. in the mixing section and 150° C. in the insulation section for 1 minute, and then continuously fed into the parallel co-rotating twin-screw extruder, and the remaining 200 phr of epoxidized soybean oil was added through three feeding ports in a ratio of 1:2.5:6 by mass for three times, and mixed at 120° C. in the heating section, 120° C. in the mixing section and 120° C. in the exhaust section for 6 minutes to obtain liquid recycled rubber.

[0038] Table 1 Properties of prepared liquid recycled rubber

[0039] Example 1 Example 2 Example 3 Mooney viscosity ML (1+4) 100℃ ＜5 ＜5 ＜5 Mooney viscosity ML (1+4) 40℃ 20 15 7

[0040] Mooney viscosity reflects the quality of rubber processing performance, molecular weight and distribution range. Rubber with high Mooney viscosity is not easy to mix evenly and extrude, and its molecular weight is high and distribution range is wide. Rubber with low Mooney viscosity is easy to stick to the roller, and its molecular weight is low and distribution range is narrow. When Mooney viscosity ML (1+4) 100℃ <5, it indicates that the molecular weight of the rubber is very low.

[0041] 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.

[0042] 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 highly oil-filled liquid recycled rubber, characterized in that: The steps include: The first step is to mix and preheat the waste rubber powder and part of the softener; In the second step, the mixed and preheated raw materials are fed into a twin-screw or multi-screw extruder for heating and preliminary cross-linking. In the third step, the raw material after preliminary de-crosslinking is fed into a parallel co-rotating twin-screw extruder, and the remaining softener is added in multiple times through multiple feeding ports on the barrel, and highly oil-filled liquid regenerated rubber is obtained after extrusion; The particle size of the waste rubber powder is 20-60 mesh, and the waste rubber powder is the rubber powder obtained by crushing waste tires; The mass ratio of the waste rubber powder, part of the softener and the remaining softener is 100:0-10:50-200; the softener is any one or more combinations of pine tar oil, epoxidized soybean oil, cycloalkane oil, paraffin oil and environmentally friendly aromatic oil.

2. The method for preparing highly oil-filled liquid recycled rubber according to claim 1, characterized in that: The mixed preheating in the first step is maintained at 100-130° C. for 5-20 min.

3. The method for preparing highly oil-filled liquid recycled rubber according to claim 1, characterized in that: In the second step, the aspect ratio of the screws of the twin-screw or multi-screw extruder is 32:1 to 48:

1.

4. The method for preparing highly oil-filled liquid recycled rubber according to claim 1, characterized in that: In the second step, the heating section temperature of the twin-screw or multi-screw extruder is 150°C to 220°C, the mixing section temperature is 220°C to 280°C, and the insulation section temperature is 150 to 220°C; the heating and preliminary de-crosslinking time is 1-10 minutes.

5. The method for preparing highly oil-filled liquid recycled rubber according to claim 1, characterized in that: In the third step, the parallel co-rotating twin-screw extruder has three feeding ports; The remaining softener is added through three feeding ports in a mass ratio of 1:1.3-2.5:1.5-6 in order; the time interval between additions is not less than 30 seconds.

6. The method for preparing highly oil-filled liquid recycled rubber according to claim 1, characterized in that: In the third step, the parallel co-rotating twin-screw extruder has a feeding and conveying premixing section, a mixing and kneading section and a compression and exhaust section; the temperature of the feeding and conveying premixing section is 80°C to 130°C, the temperature of the mixing and kneading section is 130°C to 180°C, and the temperature of the compression and exhaust section is 130°C to 80°C; the residence time of the raw materials in the third step in the parallel co-rotating twin-screw extruder is 3 to 6 minutes.