Preparation method of liquid butyl regenerated rubber

Abstract

The invention provides a preparation method of liquid butyl regenerated rubber, and belongs to the field of production of regenerated rubber materials. According to the method, the waste butyl rubber particles, the rubber regenerant and the softener are mixed in an internal mixer according to the mass ratio of 100: (3-10): (4-8), the liquid butyl regenerated rubber with the molecular weight being 9000-20000, the molecular weight distribution being 2-10 and the sol content being larger than 78% is prepared through the procedures of pre-depolymerization, depolymerization, cooling, filtering and the like, the technological process is simple, the cost is low, and the method is suitable for industrial production. The method has the advantages of high depolymerization degree, few impurities and good quality.

Description

Technical Field

[0001] The invention relates to a regenerated rubber compound manufacturing technology, in particular to a method for preparing liquid butyl regenerated rubber, and belongs to the technical field of regenerated rubber manufacturing. Background Art

[0002] Butyl rubber has the advantages of low air permeability, good thermal stability, good shock absorption, good resistance to ozone and weathering, good resistance to chemical corrosion and water vapor erosion, etc. Therefore, it is widely used in many fields such as tires, medical bottle stoppers, rubber industrial products and daily necessities. my country produces a large number of various types of waste butyl rubber products every year, among which waste butyl inner tubes are the main ones. Therefore, efficient recycling and reuse of waste butyl inner tubes can not only save resources and improve the use efficiency of butyl rubber, but also reduce pollution to the environment.

[0003] The air tightness of butyl reclaimed rubber is equivalent to that of butyl rubber, while retaining the various properties of the original rubber, making it a better material for making inner tubes; in addition, it also has some special matching advantages such as improving the dimensional stability of the product, lower heat generation, and reducing scorching, etc. Therefore, the recycling and reuse of butyl rubber has become a focus of the industry. Chinese patent (201810578049.3 A waste butyl rubber regeneration process and its preparation method) discloses a waste butyl rubber regeneration process, which uses a low-temperature continuous mixing and refining method to regenerate waste butyl rubber. In the invention, the process of continuous regeneration of waste butyl rubber by using an internal mixer, a twin-screw extruder, a rubber filter and a refiner replaces the traditional reactor under high temperature and high pressure to achieve selective breaking of chemical bonds, thereby achieving low-temperature and environmentally friendly regeneration of waste butyl rubber. However, butyl rubber is a main chain saturated rubber with good heat resistance, and regeneration and desulfurization are difficult. In this invention, the waste butyl rubber is cut into small pieces of 10mm×10mm×5mm-50mm×50mm×5mm, and the mixture is mixed in a banbury mixer for 9-12 minutes. The barrel temperature of the twin-screw extruder is set at 70-90°C, and the rotor speed of the twin-screw extruder is 30-50r / min. The waste rubber particles are large, and the desulfurization temperature and shear rate are low, so it is difficult to achieve uniform desulfurization of the waste butyl rubber, which can easily lead to the "cooked" phenomenon of the waste rubber particles, thereby affecting the overall quality of the recycled rubber.

[0004] Therefore, the butyl regenerated rubber in the prior art has problems such as uneven desulfurization degree and unsatisfactory effect. Summary of the invention

[0005] The invention provides a novel preparation method of liquid butyl regenerated rubber. By mixing waste butyl rubber particles, a rubber regenerating agent and a softener, high-quality regenerated rubber can be obtained, so as to solve the technical problems of uneven desulfurization degree and unsatisfactory effect of butyl regenerated rubber in the prior art.

[0006] The method for preparing liquid butyl regenerated rubber according to the embodiment of the present invention comprises the following steps:

[0007] Step 1: Classify, clean and split the recycled waste butyl inner tube to obtain rubber blocks with a size less than 5 cm×5 cm×5 cm;

[0008] Step 2, placing the rubber block obtained in step 1 into a crushing device to obtain waste butyl rubber particles with a particle size less than 6 mm;

[0009] Step 3, the waste butyl rubber particles, rubber regeneration agent and softener obtained in step 2 are put into an internal mixer in a mass ratio of 100:3-10:4-8 to obtain a uniformly mixed rubber material;

[0010] Step 4, placing the rubber obtained in step 3 into a closed stirring and mixing device, and discharging the material after the material temperature reaches the set temperature to obtain a pre-depolymerized rubber;

[0011] Step 5, placing the rubber obtained in step 4 into a first screw extruder, setting the temperature of the screw extruder, de-crosslinking the three-dimensional network and partially breaking the molecular chain to obtain a depolymerized rubber;

[0012] Step 6, feeding the depolymerized rubber obtained in step 5 into a second screw extruder via a continuous conveying device for cooling;

[0013] Step seven, sending the cooled rubber obtained in step six into a filtering device to obtain liquid butyl regenerated rubber after filtering; the liquid butyl regenerated rubber has a molecular weight of 9000-20000, a molecular weight distribution of 2-10, and a sol content greater than 78%.

[0014] The method for preparing liquid butyl regenerated rubber as described above, wherein the rotor speed of the internal mixer in step 3 is 50-90r / min, the filling factor is 0.3-0.8, the internal mixing time is 2-4min, and the upper push bolt pressure is 5-8kg / cm 2 .

[0015] The method for preparing liquid butyl regenerated rubber as described above, wherein the rubber regenerating agent in step three includes RV regenerating agent; and the softening agent is a mixture of any one or more of pine tar asphalt, tall oil asphalt, and paraffin oil.

[0016] In the method for preparing liquid butyl regenerated rubber as described above, the setting temperature of the stirring and mixing device in step 4 is 100-130° C., and the stirring and mixing time is 5-8 min.

[0017] The method for preparing liquid butyl regenerated rubber as described above, wherein the first screw extruder in step five is a twin-screw extruder, and the temperatures of each section are: zone one temperature 200-225°C, zone two temperature 250-270°C, zone three temperature 280-300°C, zone four temperature 200-230°C, zone five temperature 200-220°C, and die head temperature 180-200°C; the reaction time is 3-8 min.

[0018] The method for preparing liquid butyl regenerated rubber as described above, wherein the second screw extruder in step six is ​​a twin-screw extruder or a single-screw extruder, the temperature of the extruder is controlled to be 8-20° C., and the cooling time is 2-5 min.

[0019] In the method for preparing liquid butyl regenerated rubber as described above, the mesh number of the filtering device described in step seven is 80 to 120 meshes.

[0020] The invention adopts a combination of thermochemical and mechanochemical methods, and waste butyl rubber particles, rubber regeneration agent and softener are put into a banbury mixer in proportion to ensure that the materials are evenly mixed. Then, based on the poor thermal conductivity of the waste rubber particles, a closed stirring and mixing device is selected to gradually heat the materials during further mixing, so that the waste rubber particles with small particle sizes are evenly heated from the inside to the outside and reach a preliminary depolymerization state, and the three-dimensional cross-linked network structure is changed into a relatively loose structure. After entering a screw extruder, the temperature and rotation speed of the screw are controlled, so that the shearing efficiency of the material is effectively improved. After entering a second screw extruder, the rotation speed is reduced, the material is cooled, and the impurities and undepolymerized particles in the rubber are reduced by a filtering device, so that liquid butyl regenerated rubber with less impurities and good quality is finally obtained.

[0021] The liquid butyl regenerated rubber obtained in the present invention has a uniform degree of depolymerization, less "cooked" conditions, and the cross-linking bonds of the butyl rubber are greatly degraded, the network structure becomes smaller, and the original additives in the waste rubber are fully released. When the liquid regenerated rubber is used together with the raw rubber, it is easier to disperse, and the problems of poor tear resistance caused by uneven dispersion of the compounding agent when adding the regenerated rubber are effectively reduced. DETAILED DESCRIPTION

[0022] The preparation method of the liquid butyl regenerated 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: waste butyl inner tube, rubber regeneration agent, softener, etc.

[0023] The method for preparing liquid butyl regenerated rubber according to the embodiment of the present invention comprises the following steps:

[0024] Step 1: Classify, clean and split the recycled waste butyl inner tube to obtain rubber blocks with a size less than 5 cm×5 cm×5 cm;

[0025] Step 2, placing the rubber block obtained in step 1 into a crushing device to obtain waste butyl rubber particles with a particle size less than 6 mm;

[0026] Step 3, the waste butyl rubber particles, rubber regeneration agent and softener obtained in step 2 are put into an internal mixer in a mass ratio of 100:3-10:4-8 to obtain a uniformly mixed rubber material; the rotor speed of the internal mixer in step 3 is 50-90r / min, the filling factor is 0.3-0.8, the internal mixing time is 2-4min, and the upper bolt pressure is 5-8kg / cm 2 In the step 3, the rubber regenerating agent includes RV regenerating agent; the softening agent is a mixture of any one or more of pine tar asphalt, tall oil asphalt and paraffin oil.

[0027] Step 4, putting the rubber obtained in step 3 into a closed stirring and mixing device, and discharging the material after the material temperature reaches the set temperature to obtain a pre-depolymerized rubber; the set temperature of the stirring and mixing device in step 4 is 100-130°C, and the stirring and mixing time is 5-8min.

[0028] Step 5, putting the rubber obtained in step 4 into the first screw extruder, setting the temperature of the screw extruder, de-crosslinking the three-dimensional network and partially breaking the molecular chain to obtain the depolymerized rubber; the first screw extruder in step 5 is a twin-screw extruder, and the temperatures of each section are: zone 1 temperature 200-225°C, zone 2 temperature 250-270°C, zone 3 temperature 280-300°C, zone 4 temperature 200-230°C, zone 5 temperature 200-220°C, and head temperature 180-200°C; the reaction time is 3-8min.

[0029] Step six, sending the depolymerized rubber obtained in step five into a second screw extruder via a continuous conveying device for cooling; the second screw extruder in step six is ​​one of a twin-screw extruder or a single-screw extruder, the temperature of the extruder is controlled to be 8-20°C, and the cooling time is 2-5min.

[0030] Step 7, sending the cooled rubber obtained in step 6 into a filtering device, filtering to obtain liquid butyl regenerated rubber; the molecular weight of the liquid butyl regenerated rubber is 9000-20000, the molecular weight distribution is 2-10, and the sol content is greater than 78%. The mesh number of the filtering device in step 7 is 80-120 meshes.

[0031] The invention adopts a combination of thermochemical and mechanical chemical methods, and reasonably designs a process route of mixing preheating, de-crosslinking, and cooling and filtering. Waste butyl rubber particles, rubber regeneration agent, and softener are put into a banburying mixer in proportion to ensure that the materials are evenly mixed. Based on the poor thermal conductivity of the waste rubber particles, a closed stirring and mixing device is selected to gradually increase the temperature during the further mixing of the materials, so that the waste rubber particles with small particle sizes are evenly heated from the inside to the outside, and the three-dimensional crosslinking network structure is changed into a relatively loose structure, and a preliminary depolymerization state is achieved. The process of banburying and mixing further reduces the viscosity of the rubber. When the rubber enters a screw extruder, the high shearing effect of the screw is utilized at a relatively low reaction temperature to effectively promote the depolymerization of the rubber material, and also reduce the loss of the screw. After entering the second screw extruder, the temperature drops and the material is cooled. The impurities and undepolymerized particles in the rubber are reduced through the filtering device. The final liquid recycled rubber has less main chain breakage and less damage to the original additives in the waste rubber. When used downstream, it can replace more raw rubber, carbon black, operating oil and resin, with less impurities and higher quality.

[0032] The liquid butyl regenerated rubber obtained in the present invention has a uniform degree of depolymerization, less "cooked" conditions, and both the main chain and the cross-linking bonds of the butyl rubber are greatly degraded, the network structure becomes smaller, and the original additives in the waste rubber are easier to disperse when the liquid regenerated rubber is used in combination with the raw rubber, effectively reducing the problems of poor tear resistance caused by uneven dispersion of the compounding agent when adding the regenerated rubber.

[0033] Example 1

[0034] The recycled waste butyl inner tubes are classified, cleaned and divided to obtain rubber blocks with a size of less than 5cm×5cm×5cm; the obtained rubber blocks are placed in a crushing device to obtain waste butyl rubber particles with a particle size of less than 6mm; the obtained waste butyl rubber particles, rubber regeneration agent RV regeneration agent, and softener tall oil asphalt are put into an internal mixer at a mass ratio of 100:4:4 to obtain a uniformly mixed rubber material; the obtained rubber material is placed in a stirring and mixing device and stirred for 6 minutes, and the material is discharged when the temperature rises to 100-105°C to obtain a pre-depolymerized rubber material; the pre-depolymerized rubber material is placed in the first In the twin-screw extruder, the temperature of zone 1 is 200°C, the temperature of zone 2 is 250°C, the temperature of zone 3 is 280°C, the temperature of zone 4 is 200°C, the temperature of zone 5 is 200°C, the temperature of the die head is 180°C, and the reaction time is 6 minutes. The three-dimensional network is de-crosslinked and the molecular chain is partially broken to obtain a depolymerized rubber; it is sent to a second twin-screw extruder through a continuous conveying device, the temperature of the extruder is controlled to be 11°C, and cooled for 3 minutes; it enters a filtering device with a mesh number of 80, and after filtration, liquid butyl regenerated rubber is obtained with a molecular weight of 17825, a molecular weight distribution of 7.3, and a sol content of 81%.

[0035] Example 2

[0036] The recycled waste butyl inner tubes are classified, cleaned and divided to obtain rubber blocks with a size of less than 5cm×5cm×5cm; the obtained rubber blocks are placed in a crushing device to obtain waste butyl rubber particles with a particle size of less than 6mm; the obtained waste butyl rubber particles, rubber regeneration agent RV regeneration agent, and softener tall oil asphalt are put into an internal mixer at a mass ratio of 100:4:5 to obtain a uniformly mixed rubber material; the obtained rubber material is placed in a stirring and mixing device and stirred for 7 minutes, and the material is discharged when the temperature rises to 103-110°C to obtain a pre-depolymerized rubber material; the pre-depolymerized rubber material is placed in the first In the twin-screw extruder, the temperature of zone 1 is 202°C, the temperature of zone 2 is 254°C, the temperature of zone 3 is 284°C, the temperature of zone 4 is 205°C, the temperature of zone 5 is 203°C, the temperature of the die head is 180°C, and the reaction time is 6 minutes. The three-dimensional network is de-crosslinked and the molecular chain is partially broken to obtain a depolymerized rubber; it is sent to a second twin-screw extruder through a continuous conveying device, the temperature of the extruder is controlled to be 15°C, and cooled for 3 minutes; it enters a filtering device with a mesh number of 80, and after filtration, liquid butyl regenerated rubber is obtained with a molecular weight of 15378, a molecular weight distribution of 6.8, and a sol content of 83%.

[0037] Example 3

[0038] The recycled waste butyl inner tubes are classified, cleaned and divided to obtain rubber blocks with a size of less than 5cm×5cm×5cm; the obtained rubber blocks are placed in a crushing device to obtain waste butyl rubber particles with a particle size of less than 6mm; the obtained waste butyl rubber particles, rubber regeneration agent RV regeneration agent, and softener paraffin oil are put into an internal mixer at a mass ratio of 100:5:6 to obtain a uniformly mixed rubber material; the obtained rubber material is placed in a stirring and mixing device and stirred for 6 minutes, and the material is discharged when the temperature rises to 108-115°C to obtain a pre-depolymerized rubber material; the pre-depolymerized rubber material is placed in the first double In the screw extruder, the temperature of zone 1 is 207°C, the temperature of zone 2 is 258°C, the temperature of zone 3 is 280°C, the temperature of zone 4 is 217°C, the temperature of zone 5 is 213°C, the temperature of the die head is 190°C, and the reaction time is 6 minutes. The three-dimensional network is de-crosslinked and the molecular chain is partially broken to obtain a depolymerized rubber; it is sent to the second twin-screw extruder through a continuous conveying device, the temperature of the extruder is controlled to be 13°C, and cooled for 3 minutes; it enters a filtering device with a mesh number of 100, and after filtration, liquid butyl regenerated rubber is obtained with a molecular weight of 12074, a molecular weight distribution of 6.2, and a sol content of 85%.

[0039] 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.

[0040] 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 butyl regenerated rubber, It is characterized in that The following steps are involved: Step 1: Classify, clean and divide the recycled waste butyl inner tube to obtain rubber blocks with a size less than 5 cm×5 cm×5 cm; Step 2, placing the rubber block obtained in step 1 into a crushing device to obtain waste butyl rubber particles with a particle diameter less than 6 mm; Step 3, the waste butyl rubber particles, rubber regeneration agent and softener obtained in step 2 are put into an internal mixer in a mass ratio of 100:3-10:4-8 to obtain a uniformly mixed rubber material; Step 4, placing the rubber obtained in step 3 into a closed stirring and mixing device, and discharging the material after the material temperature reaches the set temperature to obtain a pre-depolymerized rubber; Step 5, placing the rubber obtained in step 4 into a first screw extruder, setting the temperature of the screw extruder, de-crosslinking the three-dimensional network and partially breaking the molecular chain to obtain a depolymerized rubber; Step 6, feeding the depolymerized rubber obtained in step 5 into a second screw extruder via a continuous conveying device for cooling; Step seven, sending the cooled rubber obtained in step six into a filtering device to obtain liquid butyl regenerated rubber after filtering; the liquid butyl regenerated rubber has a molecular weight of 9000-20000, a molecular weight distribution of 2-10, and a sol content greater than 78%.

2. The method for preparing liquid butyl regenerated rubber according to claim 1, It is characterized in that In the step 3, the rotor speed of the internal mixer is 50-90 r / min, the filling factor is 0.3-0.8, the mixing time is 2-4 min, and the upper push bolt pressure is 5-8 kg / cm 2 .

3. The method for preparing liquid butyl regenerated rubber according to claim 1, It is characterized in that In the step 3, the rubber regenerating agent includes RV regenerating agent; the softening agent is a mixture of any one or more of pine tar asphalt, tall oil asphalt and paraffin oil.

4. The method for preparing liquid butyl regenerated rubber according to claim 1, It is characterized in that The setting temperature of the stirring and mixing device in step 4 is 100-130° C., and the stirring and mixing time is 5-8 minutes.

5. The method for preparing liquid butyl regenerated rubber according to claim 1, It is characterized in that The first screw extruder in step 5 is a twin-screw extruder, and the temperatures of each section are: zone 1 temperature 200-225°C, zone 2 temperature 250-270°C, zone 3 temperature 280-300°C, zone 4 temperature 200-230°C, zone 5 temperature 200-220°C, and die head temperature 180-200°C; the reaction time is 3-8min.

6. The method for preparing liquid butyl regenerated rubber according to claim 1, It is characterized in that The second screw extruder in step six is ​​a twin-screw extruder or a single-screw extruder, and the temperature of the extruder is controlled to be 8-20° C., and the cooling time is 2-5 min.

7. The method for preparing liquid butyl regenerated rubber according to claim 1, It is characterized in that The mesh number of the filtering device described in step seven is 80 to 120 meshes.