Method for preparing liquid reclaimed rubber from biomass oil

Abstract

The invention provides a method for preparing liquid reclaimed rubber from biomass oil, and belongs to the field of rubber production and manufacturing. Industrial lignin and waste rubber are dried and uniformly mixed, a co-pyrolysis reaction is carried out in a thermal cracking reactor, obtained biomass oil and waste rubber powder are stirred and mixed and then enter a screw extruder, decrosslinking of a rubber network is realized through heating and the high-shear effect of a screw, and finally the prepared liquid reclaimed rubber is high in oil content, high in mechanical strength and high in mechanical strength. The viscosity is low, the energy consumption in the production process is low, and the additional value of resource utilization of the waste rubber and the industrial lignin is greatly improved.

Description

Technical Field

[0001] The invention relates to a regenerated rubber manufacturing technology, in particular to a method for preparing liquid regenerated rubber from biomass oil, and belongs to the technical field of regenerated rubber production and 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 regenerating agent and swelling agent, 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. During the regeneration process, the swelling agent first penetrates into the cross-linked network of the vulcanized rubber, weakening the interaction between the rubber macromolecular chains and between the rubber macromolecular chains and the filler, expanding the volume, and increasing the distance between the rubber macromolecular chains, which is conducive to the diffusion of additives such as regeneration activators into the cross-linked network. The rubber regenerating 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 secondary pollution to the environment is easily caused.

[0005] Lignin, one of the three main components of woody biomass, is composed of randomly bonded phenylpropane structural units. It has the outstanding characteristics of wide sources, huge reserves, and recyclable renewable, and has great application potential. However, in actual production, lignin is mainly discharged as waste or directly burned as fuel, resulting in serious waste of resources.

[0006] Therefore, finding ways to utilize lignin at a high value has become the focus of many research studies. Pyrolysis technology is a process that rapidly pyrolyzes biomass into liquid bio-oil, solid charcoal and non-condensable gases under medium temperature, short residence time and oxygen-free conditions. The bio-oil obtained by thermal cracking of lignin can be used as a swelling agent in the rubber regeneration process, while expanding the application range of lignin in rubber materials and improving its high-value utilization rate. Summary of the invention

[0007] The present invention provides a novel method for preparing liquid reclaimed rubber from biomass oil, wherein lignin and waste rubber are subjected to a co-pyrolysis reaction in a thermal cracking reactor, thereby obtaining biomass oil to achieve de-crosslinking of the rubber network, thereby solving the technical problem of low utilization rate of lignin in the field of rubber processing in the prior art.

[0008] The method for preparing liquid regenerated rubber from biomass oil according to an embodiment of the present invention comprises the following steps:

[0009] The first step is to classify, sort, clean and dry the recycled waste rubber, and put it into a crushing device to obtain 20-60 mesh waste rubber powder;

[0010] The second step is to dry, grind and crush the recovered industrial lignin to obtain lignin particles with a particle size of 0.1-0.5 mm;

[0011] In the third step, the waste rubber powder obtained in the first step, the lignin particles obtained in the second step, and the catalyst are put into a first stirring and mixing device to mix them evenly;

[0012] The fourth step is to transport the material obtained in the third step to a thermal cracking reactor at a reaction temperature of 380°C-480°C to perform a co-pyrolysis reaction to obtain biomass thermal cracking gas with solid carbon residue;

[0013] The fifth step is to send the biomass pyrolysis gas with solid carbon residue obtained in the fourth step into a cyclone separator, separate the carbon residue, and then enter a cooling device for cooling for 2-5 minutes, discharge non-condensable gas, and obtain biomass oil;

[0014] Step 6: Put the waste rubber powder obtained in the first step and the biomass oil obtained in the fifth step into the second stirring and mixing device, stir for 1-3 minutes, and then feed the discharged material into the first twin-screw extruder, control the temperature of the first screw extruder to 230-290° C., and react for 2-5 minutes;

[0015] In the seventh step, the material obtained in the sixth step is fed into a second screw extruder, the temperature of the screw extruder is controlled to be 5-20°C, cooled for 1-3 minutes, and liquid regenerated rubber is obtained after extrusion; the liquid regenerated rubber has a sol content greater than 80%, a molecular weight of 9000-16000, and a molecular weight distribution of 4-10.

[0016] In the method for preparing liquid regenerated rubber from biomass oil as described above, the moisture content of industrial lignin in the second step is less than 2%, and the industrial lignin is a mixture of one or more of alkali lignin, sulfate lignin, and lignin sulfonate.

[0017] The method for preparing liquid regenerated rubber from biomass oil as described above, wherein the catalyst in the third step is one of the molecular sieve catalysts ZSM-5, HZSM-5 and MCM-41; the ratio of waste rubber powder, lignin particles and catalyst is 10:3-5:0.5-1.5.

[0018] The method for preparing liquid regenerated rubber from biomass oil as described above, wherein the thermal cracking reaction device in the fourth step is one of a fluidized bed reactor, a moving bed reactor, and a fixed bed reactor, and the residence time of the thermal cracking gas is 0.2s-0.5s.

[0019] The method for preparing liquid regenerated rubber from biomass oil as described above, wherein the cooling medium in the fifth step is an oil substance and the temperature is 120-150°C.

[0020] The method for preparing liquid reclaimed rubber from biomass oil as described above, wherein in the sixth step, the ratio of waste rubber powder to biomass oil is 100:20-40, the first screw extruder is a co-rotating twin-screw extruder, the aspect ratio of the screw is 28-36:1, the conveying section temperature of the screw extruder is 240-270°C, the shear section temperature is 270-290°C, and the cooling section temperature is 230-250°C.

[0021] In the method for preparing liquid regenerated rubber from biomass oil as described above, the second screw extruder in the seventh step is a single screw extruder or a twin screw extruder, and the aspect ratio of the screw is 24-32:1.

[0022] The embodiments of the present invention have at least the following beneficial effects:

[0023] The uniformly mixed waste rubber powder, industrial lignin and catalyst are co-pyrolyzed in a pyrolysis reactor. Lignin is first pyrolyzed to produce active free radicals. Existing studies have shown that the thermal degradation of polymers is mainly a free radical-dominated mechanism. Therefore, the active free radicals released by the pyrolysis of lignin will effectively promote the de-crosslinking reaction of the waste rubber powder. The effective hydrogen-carbon ratio of the waste rubber powder is relatively high, and the hydrogen free radicals are released into the "free radical pool". Through the hydrogen transfer reaction, the bio-oil produced by the pyrolysis of lignin is promoted from oxygen-containing compounds to hydrocarbons. The presence of the catalyst can not only improve the pyrolysis efficiency of lignin, but also effectively reduce the production of coke during the pyrolysis process and promote the formation of aromatic compounds, thereby improving the quality of pyrolysis biomass oil.

[0024] The biomass oil obtained by cooling after cracking has a high temperature, has a composition similar to that of aromatic hydrocarbon oil, and has a low molecular weight. It is used as a softener in the regeneration process of waste rubber powder. Using the principle of similar compatibility, the waste rubber powder and the high proportion of biomass oil added can be stirred and mixed to a uniformly dispersed state in a relatively short time. At the same time, the heat of the biomass oil itself can be effectively transferred to the waste rubber powder. The mixed materials enter the first twin-screw extruder. At a relatively low regeneration temperature, the high shearing effect of the screw can be used to achieve the de-crosslinking of the three-dimensional network of the waste rubber powder. The liquid recycled rubber finally prepared has a high oil content and low viscosity. It can replace operating oil when added to the rubber composition, and the energy consumption in the production process is low, which greatly increases the added value of the resource utilization of waste rubber and industrial lignin. DETAILED DESCRIPTION

[0025] The method for preparing liquid regenerated rubber from biomass oil 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: lignin, waste rubber, biomass oil, screw extruder, etc.

[0026] The method for preparing liquid regenerated rubber from biomass oil in this embodiment comprises the following steps:

[0027] The first step is to classify, sort, clean and dry the recycled waste rubber, and put it into a crushing device to obtain 20-60 mesh waste rubber powder;

[0028] In the second step, the recovered industrial lignin is dried, ground and pulverized to obtain lignin particles with a particle size of 0.1-0.5 mm; in the second step, the moisture content of the industrial lignin is less than 2%, and the industrial lignin is a mixture of one or more of alkali lignin, sulfate lignin and lignin sulfonate.

[0029] In the third step, the waste rubber powder obtained in the first step, the lignin particles obtained in the second step, and the catalyst are put into a first stirring and mixing device and mixed evenly; the catalyst in the third step is one of the molecular sieve catalysts ZSM-5, HZSM-5 and MCM-41; the ratio of the waste rubber powder, the lignin particles, and the catalyst is 10:3-5:0.5-1.5.

[0030] The fourth step is to transport the material obtained in the third step to a thermal cracking reactor at a reaction temperature of 380°C-480°C to carry out a co-pyrolysis reaction to obtain biomass thermal cracking gas with solid carbon residue; the thermal cracking reaction device in the fourth step is one of a fluidized bed reactor, a moving bed reactor, and a fixed bed reactor, and the thermal cracking gas residence time is 0.2s-0.5s.

[0031] In the fifth step, the biomass pyrolysis gas with solid carbon residue obtained in the fourth step is sent to a cyclone separator, and after the carbon residue is separated, it enters a cooling device, is cooled for 2-5 minutes, and non-condensable gases are discharged to obtain biomass oil; the cooling medium of the cooling device in the fifth step is an oil substance, and the temperature is 120-150°C.

[0032] Step 6: Put the waste rubber powder obtained in the first step and the biomass oil obtained in the fifth step into the second stirring and mixing device, stir for 1-3 minutes, and then feed the discharged material into the first twin-screw extruder, control the temperature of the first screw extruder to 230-290° C., and react for 2-5 minutes;

[0033] In the sixth step, the ratio of waste rubber powder to biomass oil is 100:20-40, the first screw extruder is a co-rotating twin-screw extruder, the aspect ratio of the screw is 28-36:1, the conveying section temperature of the screw extruder is 240-270°C, the shear section temperature is 270-290°C, and the cooling section temperature is 230-250°C.

[0034] In the seventh step, the material obtained in the sixth step is fed into a second screw extruder, the temperature of the screw extruder is controlled to be 5-20°C, cooled for 1-3 minutes, and liquid regenerated rubber is obtained after extrusion; the liquid regenerated rubber has a sol content greater than 80%, a molecular weight of 9000-16000, and a molecular weight distribution of 4-10.

[0035] The second screw extruder in the seventh step is a single screw extruder or a twin screw extruder, and the aspect ratio of the screw is 24-32:1.

[0036] The present invention dries and uniformly mixes industrial lignin and waste rubber, performs co-pyrolysis reaction in a thermal cracking reactor, and the obtained biomass oil and waste rubber powder are stirred and mixed before entering a screw extruder, and de-crosslinking of the rubber network is achieved through heating and high shearing action of the screw. The liquid reclaimed rubber finally prepared has high oil content and low viscosity, and low energy consumption in the production process, thereby greatly improving the added value of the resource utilization of waste rubber and industrial lignin.

[0037] The present invention pyrolyzes the uniformly mixed waste rubber powder, industrial lignin and catalyst in a pyrolysis reactor. Lignin is first pyrolyzed to generate active free radicals. Existing studies have shown that the thermal degradation of high molecular weight polymers is mainly a free radical-dominated mechanism. Therefore, the active free radicals released by the pyrolysis of lignin will effectively promote the de-crosslinking reaction of the waste rubber powder. The effective hydrogen-carbon ratio of the waste rubber powder is relatively high, and the hydrogen free radicals are released into the "free radical pool". The bio-oil produced by the pyrolysis of lignin is promoted to be converted from oxygen-containing compounds to hydrocarbons through hydrogen transfer reaction. The presence of the catalyst can not only improve the pyrolysis efficiency of lignin, but also effectively reduce the generation of coke during the pyrolysis process, promote the formation of aromatic compounds, and thus improve the quality of pyrolysis biomass oil.

[0038] The biomass oil obtained by cooling after cracking has a high temperature, has a composition similar to that of aromatic hydrocarbon oil, and has a low molecular weight. It is used as a softener in the regeneration process of waste rubber powder. Using the principle of similar compatibility, the waste rubber powder and the high proportion of biomass oil added can be stirred and mixed to a uniformly dispersed state in a relatively short time. At the same time, the heat of the biomass oil itself can be effectively transferred to the waste rubber powder. The mixed materials enter the first twin-screw extruder. At a relatively low regeneration temperature, the high shearing effect of the screw can be used to achieve the de-crosslinking of the three-dimensional network of the waste rubber powder. The liquid recycled rubber finally prepared has a high oil content and low viscosity. It can replace operating oil when added to the rubber composition, and the energy consumption in the production process is low, which greatly increases the added value of the resource utilization of waste rubber and industrial lignin.

[0039] Example 1

[0040] S1: The recycled waste rubber is classified, sorted, cleaned, dried, and put into a crushing device to obtain 20-mesh waste tire rubber powder;

[0041] S2: drying, grinding and crushing the recovered industrial alkali lignin to obtain lignin particles with a particle size of 0.3 mm;

[0042] S3: putting the lignin particles obtained in S2, the waste rubber powder obtained in S1, and the catalyst HZSM-5 into the first stirring and mixing device in a mass ratio of 10:4:0.5, and mixing them evenly;

[0043] S4: the material obtained in S3 is transported to a fluidized bed reactor, the reaction temperature is 450°C, a co-pyrolysis reaction is carried out, and the residence time of the pyrolysis gas is 0.4s;

[0044] S5: sending the biomass pyrolysis gas with solid carbon residue obtained in S4 into a cyclone separator, separating the carbon residue and then entering a cooling device, cooling with cooling oil for 3 minutes, discharging non-condensable gas, and obtaining biomass oil;

[0045] S6: the waste rubber powder obtained in S1 and the biomass oil obtained in S5 are put into the second stirring and mixing device at a mass ratio of 100:29, stirred for 2 minutes, and discharged into the first twin-screw extruder, the screw length-diameter ratio is 32:1, the temperature of the conveying section of the screw extruder is controlled to be 240°C, the temperature of the shearing section is 290°C, the temperature of the cooling section is 230°C, and the reaction is carried out for 3 minutes;

[0046] S7: The material obtained in S6 is fed into the second twin-screw extruder with a screw length-diameter ratio of 28:1. The temperature of the screw extruder is controlled at 12°C and cooled for 2 minutes. Liquid reclaimed rubber is obtained after extrusion, with a gel content greater than 80%, a molecular weight of 13647, and a molecular weight distribution of 7.5.

[0047] Example 2

[0048] S1: Classify, sort, clean and dry the recycled waste rubber, and put it into a crushing device to obtain 30 mesh waste tire tread rubber powder;

[0049] S2: drying, grinding and crushing the recovered industrial alkali lignin to obtain lignin particles with a particle size of 0.2 mm;

[0050] S3: putting the lignin particles obtained in S2, the waste rubber powder obtained in S1, and the catalyst ZSM-5 into the first stirring and mixing device in a mass ratio of 10:3:0.5, and mixing them evenly;

[0051] S4: the material obtained in S3 is transported to a fluidized bed reactor, the reaction temperature is 470°C, a co-pyrolysis reaction is carried out, and the residence time of the pyrolysis gas is 0.5s;

[0052] S5: sending the biomass pyrolysis gas with solid carbon residue obtained in S4 into a cyclone separator, separating the carbon residue and then entering a cooling device, cooling with cooling oil for 3 minutes, discharging non-condensable gas, and obtaining biomass oil;

[0053] S6: the waste rubber powder obtained in S1 and the biomass oil obtained in S5 are put into the second stirring and mixing device at a mass ratio of 100:25, stirred for 3 minutes, and discharged into the first twin-screw extruder, the screw length-diameter ratio is 36:1, the temperature of the conveying section of the screw extruder is controlled to be 250°C, the temperature of the shearing section is 285°C, the temperature of the cooling section is 236°C, and the reaction is carried out for 3 minutes;

[0054] S7: The material obtained in S6 is fed into the second twin-screw extruder with a screw length-diameter ratio of 32:1. The temperature of the screw extruder is controlled at 15°C and cooled for 2 minutes. Liquid reclaimed rubber is obtained after extrusion, with a gel content greater than 80%, a molecular weight of 12074, and a molecular weight distribution of 8.1.

[0055] Example 3

[0056] S1: Classify, sort, clean and dry the recycled waste rubber, and put it into a crushing device to obtain 40 mesh waste tire tread rubber powder;

[0057] S2: drying, grinding and crushing the recovered industrial kraft lignin to obtain lignin particles with a particle size of 0.2 mm;

[0058] S3: putting the lignin particles obtained in S2, the waste rubber powder obtained in S1, and the catalyst ZSM-5 into the first stirring and mixing device in a mass ratio of 10:5:1.5, and mixing them evenly;

[0059] S4: the material obtained in S3 is transported to a fluidized bed reactor, the reaction temperature is 460°C, a co-pyrolysis reaction is carried out, and the residence time of the pyrolysis gas is 0.4s;

[0060] S5: sending the biomass pyrolysis gas with solid carbon residue obtained in S4 into a cyclone separator, separating the carbon residue and then entering a cooling device, cooling with cooling oil for 3 minutes, discharging non-condensable gas, and obtaining biomass oil;

[0061] S6: the waste rubber powder obtained in S1 and the biomass oil obtained in S5 are put into the second stirring and mixing device at a mass ratio of 100:34, stirred for 3 minutes, and discharged into the first twin-screw extruder, the screw length-diameter ratio is 36:1, the temperature of the conveying section of the screw extruder is controlled to be 252°C, the temperature of the shearing section is 296°C, the temperature of the cooling section is 243°C, and the reaction is carried out for 3 minutes;

[0062] S7: The material obtained in S6 is fed into the second twin-screw extruder with a screw length-diameter ratio of 28:1. The temperature of the screw extruder is controlled at 20°C and cooled for 2 minutes. Liquid reclaimed rubber is obtained after extrusion, with a gel content greater than 80%, a molecular weight of 10578, and a molecular weight distribution of 6.4.

[0063] 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.

[0064] 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 liquid regenerated rubber from biomass oil, characterized in that: The following steps are involved: The first step is to classify, sort, clean and dry the recycled waste rubber, and put it into a crushing device to obtain 20-60 mesh waste rubber powder; The second step is to dry, grind and crush the recovered industrial lignin to obtain lignin particles with a particle size of 0.1-0.5 mm; In the third step, the waste rubber powder obtained in the first step, the lignin particles obtained in the second step, and the catalyst are put into a first stirring and mixing device to mix them evenly; The fourth step is to transport the material obtained in the third step to a thermal cracking reactor at a reaction temperature of 380°C-480°C to perform a co-pyrolysis reaction to obtain biomass thermal cracking gas with solid carbon residue; The fifth step is to send the biomass pyrolysis gas with solid carbon residue obtained in the fourth step into a cyclone separator, separate the carbon residue, and then enter a cooling device for cooling for 2-5 minutes, discharge non-condensable gas, and obtain biomass oil; Step 6: Put the waste rubber powder obtained in the first step and the biomass oil obtained in the fifth step into the second stirring and mixing device, stir for 1-3 minutes, and then feed the discharged material into the first twin-screw extruder, control the temperature of the first screw extruder to 230-290° C., and react for 2-5 minutes; In the seventh step, the material obtained in the sixth step is fed into a second screw extruder, the temperature of the screw extruder is controlled to be 5-20°C, cooled for 1-3 minutes, and liquid regenerated rubber is obtained after extrusion; the liquid regenerated rubber has a sol content greater than 80%, a molecular weight of 9000-16000, and a molecular weight distribution of 4-10.

2. The method for preparing liquid regenerated rubber from biomass oil according to claim 1, characterized in that: In the second step, the moisture content of the industrial lignin is less than 2%, and the industrial lignin is a mixture of one or more of alkali lignin, sulfate lignin, and lignin sulfonate.

3. The method for preparing liquid regenerated rubber from biomass oil according to claim 1, characterized in that: The catalyst in the third step is one of the molecular sieve catalysts ZSM-5, HZSM-5 and MCM-41; the ratio of waste rubber powder, lignin particles and catalyst is 10:3-5:0.5-1.

5.

4. The method for preparing liquid regenerated rubber from biomass oil according to claim 1, characterized in that: The thermal cracking reaction device in the fourth step is one of a fluidized bed reactor, a moving bed reactor or a fixed bed reactor, and the residence time of the thermal cracking gas is 0.2s-0.5s.

5. The method for preparing liquid regenerated rubber from biomass oil according to claim 1, characterized in that: In the fifth step, the cooling medium is oily substance, and the temperature is 120-150°C.

6. The method for preparing liquid regenerated rubber from biomass oil according to claim 1, characterized in that: In the sixth step, the ratio of waste rubber powder to biomass oil is 100:20-40, the first screw extruder is a co-rotating twin-screw extruder, the aspect ratio of the screw is 28-36:1, the conveying section temperature of the screw extruder is 240-270°C, the shear section temperature is 270-290°C, and the cooling section temperature is 230-250°C.

7. The method for preparing liquid regenerated rubber from biomass oil according to claim 1, characterized in that: The second screw extruder in the seventh step is a single screw extruder or a twin screw extruder, and the aspect ratio of the screw is 24-32:1.