Preparation method of peculiar-smell-free liquid rubber

Abstract

The invention provides a preparation method of odor-free liquid rubber, and belongs to the field of rubber production and manufacturing. The method comprises the following steps: mixing raw materials; removing odor at low temperature; heating and softening; water-cooling and deodorizing; raising the temperature; and carrying out thermal degradation, cooling and glue discharging. According to the invention, after solid rubber is mixed with an auxiliary agent, especially a deodorant, the mixture is subjected to molecular chain breakage by a high-shear extruder and water-cooling deodorization, the molecular chain is further broken by a reheating and high-temperature extruder, reactive deodorization can be carried out in each extrusion stage and water-cooling stage, and finally cooling is carried out by a cooling device. And preparing the high-molecular-weight rubber into the low-molecular-weight odor-free liquid rubber.

Description

Technical Field

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

[0002] Liquid rubber refers to a viscous polymer material that is fluid at room temperature, and its properties change with changes in microstructure and molecular weight. Liquid rubber, especially liquid natural rubber, has a similar structure to most commonly used rubbers such as natural rubber, isoprene rubber, and butadiene rubber, so it has good compatibility and can participate in the vulcanization reaction of rubber composites during the vulcanization process, enter the final cross-linking structure, and improve the vulcanization, wear and tear, processing and molding properties of the composite materials.

[0003] There are two methods for preparing liquid rubber: small molecule polymerization and macromolecular degradation. Each of the two preparation methods has obvious advantages and disadvantages. The small molecule polymerization method mainly includes anionic polymerization, free radical polymerization and coordination polymerization. Compared with the macromolecular degradation method, the advantage of the small molecule polymerization method is that the reaction controllability is strong, the molecular weight and its distribution are convenient to adjust, and functional group modification is carried out; the disadvantage is that the conditions required for the reaction are complex and the cost of industrial production is high. The macromolecular degradation method refers to the use of rubber macromolecules as raw materials, and various conditions such as light, heat, and chemical reagents are used to break the rubber main chain to generate liquid natural rubber. The advantage is that the preparation conditions are simple and convenient for large-scale industrial production; the method of preparing liquid rubber by extrusion with a screw extruder can achieve control of the product molecular weight and its distribution through the control of process parameters. The disadvantage is that it is difficult to adjust the product molecular weight and its distribution, the product has a strong odor, and it is difficult to produce functional group-modified products.

[0004] Invention CN117986689A discloses a process for preparing liquid rubber using waste latex as a raw material at low temperature using a screw extruder, wherein natural rubber is added to an internal mixer for internal mixing, and then conveyed to a first twin-screw extruder through a continuous closed feeding device, and the good heat transfer capacity of the barrel wall and the screw core shaft and the high shearing effect of the screw are utilized to achieve the breaking of the natural rubber molecular chain at low temperature, and then the natural rubber enters a second twin-screw extruder through a conveying device, and the good heat transfer effect of the co-rotating twin-screw equipment is also utilized to complete the cooling and conveying process of the natural rubber.

[0005] The invention uses a two-stage extruder and utilizes high shear physical action to cut off the macromolecular chains. Compared with linear raw rubber molecular chains, vulcanized rubber has cross-linking points and cross-linking defects that are more easily cut by the screw. Therefore, this method can ultimately reduce the molecular weight and is suitable for the recycling of vulcanized rubber such as discarded condoms and latex gloves.

[0006] However, the heating temperature used in the invention is low and is insufficient to provide energy for large-scale continuous breaking of the main chain. It only utilizes shearing action, and the cross-linked structure inevitably exists in the rubber after shearing. Therefore, it is not suitable for raw rubber as raw material, that is, it is not suitable for thermal degradation preparation of liquid rubber.

[0007] Invention CN117341081A discloses a high-performance, low-cost bio-based liquid natural rubber and a preparation method thereof. The natural rubber is added into an internal mixer for internal mixing, and then conveyed to a first twin-screw extruder through a continuous closed feeding device. The good heat transfer capacity of the barrel wall and the screw core shaft and the high shearing effect of the screw are utilized to achieve the breaking of the natural rubber molecular chain at low temperature. The natural rubber enters the second twin-screw extruder through a conveying device, and the good heat transfer effect of the co-rotating twin-screw equipment is also utilized to complete the cooling and conveying process of the natural rubber, thereby obtaining a liquid natural rubber with a number average molecular weight Mn of 6000 to 18000, a molecular weight distribution of 2 to 6, and low odor.

[0008] The invention uses a two-stage screw extruder, takes raw rubber as raw material, utilizes high speed parameters, and prepares liquid rubber by high shearing action.

[0009] Compared with invention CN117986689A, the barrel heating temperature of this invention is increased, but the energy provided by the heating is still not enough to break the main chain extensively and continuously. However, within the two-stage extruder stroke, there is a limit to the chain breaking by shearing action while ensuring continuous production efficiency.

[0010] The odor of the product is improved by adding inorganic silicates, but inorganic silicates can only play a role of physical adsorption and have no actual reaction with the odor molecules. They are just blocked but not eliminated. Therefore, in the subsequent use process, the inorganic silicates will inevitably have changes in the dispersion scale during processing, and the adsorbed odor molecules will escape again, causing pollution. Summary of the invention

[0011] The invention provides a novel method for preparing odor-free liquid rubber, which can remove odor to the maximum extent by performing reactive deodorization under various temperature conditions, so as to solve the technical problem that odor-free liquid rubber is difficult to produce in the prior art.

[0012] The method for preparing the odorless liquid rubber according to the embodiment of the present invention comprises the following steps:

[0013] The first step is to mix the raw materials; mix the raw rubber, deodorant, antioxidant, peptizer and activator in a mixing device, control the discharge temperature and Mooney viscosity, and discharge the mixed rubber produced by the mixing device into the extruder A;

[0014] The second step is low-temperature deodorization; the screw speed and barrel temperature of extruder A are set to break the macromolecular chains of the mixed rubber by shearing, so that the deodorant reacts with the mixed rubber to deodorize; the mixed rubber in extruder A is discharged from extruder B;

[0015] The third step is heating and softening. The screw speed and barrel temperature of extruder B are set, the rubber compound is heated and softened, and the deodorant in the rubber compound continues to react and deodorize. A vacuum device is used at the end of extruder B to extract by-products to reduce the odor, and the rubber compound in sheets is discharged from the die head.

[0016] The fourth step is water cooling and deodorization. The rubber material is placed in a pool of warm water at 50-60℃, soaked in the pool for 1 minute and then dried to remove the residual odor caused by the chain breaking reaction during the heating and softening process.

[0017] Step 5: Heating again; setting the screw speed and barrel temperature of extruder C, the dried rubber material enters the hopper of extruder C, and heating again to soften the rubber material again, and then discharges it into extruder D;

[0018] Step 6: thermal degradation; set the screw speed and barrel temperature of extruder D to perform thermal degradation, the deodorant reacts to remove odor, a vacuum device is used in the middle and end of the extruder to extract by-products to reduce odor, and the rubber enters the cooling device;

[0019] The seventh step is cooling and degumming. Set the parameters of the cooling device. After the rubber material is cooled by the cooling device, control the final degumming temperature, and finally discharge and collect the liquid rubber product.

[0020] The method for preparing odorless liquid rubber as described above, wherein the mixing device is any one or more of an internal mixer and an open mixer connected in series; the Mooney viscosity of the mixing device is 45-65, and the temperature of the rubber material is 110-120°C.

[0021] The method for preparing odorless liquid rubber as described above, wherein the raw rubber comprises any one or more combinations of natural rubber, eucommia rubber, isoprene rubber, butadiene rubber, styrene butadiene rubber, nitrile rubber and SBS;

[0022] The deodorant is a mixture of at least one of inorganic carbonate and nano titanium dioxide and polyacrylate; the mass ratio of inorganic carbonate and / or nano titanium dioxide to polyacrylate is 1:1-3;

[0023] The antioxidant is any one or more of antioxidant 4020, antioxidant 4010NA, antioxidant 2246, and antioxidant RD;

[0024] The peptizer is any one or more of peptizers A82, A86, A60, and HT105;

[0025] The activator is an alkyl disulfide;

[0026] The mass ratio of the raw rubber, the deodorant, the antioxidant, the peptizer and the activator is 1000:0-3.5:10-30:0-30:0-100.

[0027] The method for preparing odorless liquid rubber as described above, wherein the extruder A is a twin-screw extruder, a triple-screw extruder or a planetary screw extruder;

[0028] The extruder A has an aspect ratio of 40-50:1, the length of the screw shearing element accounts for no less than 30% of the total screw length, the rotation speed is 70-100rpm, the barrel heating temperature is 160-180°C, and the rubber residence time is no less than 50s.

[0029] The method for preparing odorless liquid rubber as described above, wherein the extruder B is a single-screw extruder, a twin-screw extruder, a three-screw extruder or a planetary screw extruder with enhanced shearing action;

[0030] The extruder B has an aspect ratio of 40-50:1, the length of the screw shearing element accounts for no less than 25% of the total screw length, the rotation speed is 60-100rpm, the barrel heating temperature is 240-280°C, and the rubber residence time is no less than 60s.

[0031] The method for preparing odorless liquid rubber as described above, wherein during the water cooling deodorization process, a liquid deodorant needs to be added to the water pool; the liquid deodorant is a combination of any one or more of ricinoleic acid zinc salt and soybean oleate; the mass addition amount of the liquid deodorant in water does not exceed 5‰.

[0032] The method for preparing odorless liquid rubber as described above, wherein the extruder C is a single-screw extruder, a twin-screw extruder, a three-screw extruder or a planetary screw extruder;

[0033] The extruder C has an aspect ratio of 40-50:1, a screw shear length that accounts for no less than 25% of the total screw length, a rotation speed of 60-100 rpm, a barrel heating temperature of 240-280°C, and a rubber residence time of no less than 30s.

[0034] The method for preparing odorless liquid rubber as described above, wherein the extruder D is a twin-screw extruder, a three-screw extruder or a planetary screw extruder having both shearing and conveying functions;

[0035] The extruder D has an aspect ratio of 40 to 60:1, a screw meshing element length of not less than 30% of the total screw length, a shear element length of not less than 15% of the total screw length, a rotation speed of 35 to 140 rpm, a barrel heating temperature of 280 to 350°C, and a rubber residence time of not less than 100 s.

[0036] The method for preparing odorless liquid rubber as described above, wherein the cooling device is one or two of a screw extruder and a stirring tank connected in series that can provide cooling effect to the rubber; the cooling effect of the cooling device is: within a cooling time of 60s, the final discharge temperature of the rubber is less than 100°C.

[0037] The present invention utilizes the advantages of the extruder such as uniform thermal shearing, high efficiency, and precise temperature control to prepare liquid rubber through thermal degradation. The macromolecular chains are first broken at low temperature using high shearing action, and then the main chain is continuously broken using high temperature to provide energy.

[0038] The liquid rubber product obtained by the present invention has similar performance to conventional liquid rubber on the market; compared with the synthesis method, no solvent is used, and the requirements for reaction conditions are easier to achieve than the synthesis method; a screw extruder is used for preparation, and the preparation process has the characteristics of high efficiency, continuity, environmental protection, easy scale-up and industrialization; compared with the traditional screw extrusion method, the product has no odor. DETAILED DESCRIPTION

[0039] The method for preparing the odor-free liquid 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: raw rubber, deodorant, antioxidant, peptizer, activator, single-screw extruder, twin-screw extruder, three-screw extruder or planetary screw extruder, etc.

[0040] The method for preparing the odor-free liquid rubber of the present embodiment comprises the following steps:

[0041] The first step is to mix the raw materials; mix the mixture of raw rubber, deodorant, antioxidant, peptizer and activator in a mixing device, control the discharge temperature and Mooney viscosity, and discharge the mixed rubber produced by the mixing device into the extruder A; wherein the mixing device is any one or more of an internal mixer and an open mixer connected in series; the Mooney viscosity of the discharge of the mixing device is 45-65, and the temperature of the discharge rubber is 110-120°C.

[0042] The raw rubber includes any one or more of natural rubber, eucommia rubber, isoprene rubber, butadiene rubber, styrene-butadiene rubber, nitrile rubber and SBS;

[0043] The deodorant is a mixture of at least one of inorganic carbonate and nano titanium dioxide and polyacrylate; the mass ratio of inorganic carbonate and / or nano titanium dioxide to polyacrylate is 1:1-3;

[0044] The antioxidant is any one or more of antioxidant 4020, antioxidant 4010NA, antioxidant 2246, and antioxidant RD;

[0045] The peptizer is any one or more of peptizers A82, A86, A60, and HT105;

[0046] The activator is an alkyl disulfide;

[0047] The mass ratio of the raw rubber, the deodorant, the antioxidant, the peptizer and the activator is 1000:0-3.5:10-30:0-30:0-100.

[0048] The second step is low-temperature deodorization; the screw speed and barrel temperature of the extruder A are set to break the macromolecular chains of the mixed rubber by shearing, so that the deodorant reacts with the mixed rubber to deodorize; the mixed rubber in the extruder A is discharged to the extruder B; the extruder A is a twin-screw extruder, a three-screw extruder or a planetary screw extruder;

[0049] The extruder A has an aspect ratio of 40-50:1, the length of the screw shearing element accounts for no less than 30% of the total screw length, the rotation speed is 70-100rpm, the barrel heating temperature is 160-180°C, and the rubber residence time is no less than 50s.

[0050] The third step is heating and softening; the screw speed and barrel temperature of the extruder B are set, the rubber mix is ​​heated and softened, the deodorant in the rubber mix continues to react and deodorize, a vacuum device is used at the end of the extruder B to extract by-products to reduce the odor, and the rubber material in sheet form is discharged from the die; the extruder B is a single-screw extruder, a twin-screw extruder, a three-screw extruder or a planetary screw extruder with enhanced shearing action;

[0051] The extruder B has an aspect ratio of 40-50:1, the length of the screw shearing element accounts for no less than 25% of the total screw length, the rotation speed is 60-100rpm, the barrel heating temperature is 240-280°C, and the rubber residence time is no less than 60s.

[0052] The fourth step is water cooling for deodorization; the rubber material is discharged into a pool of warm water at 50-60°C, soaked in the pool for 1 minute and then dried to remove the residual odor caused by the chain breaking reaction during the heating and softening process; during the water cooling deodorization process, a liquid deodorant needs to be added to the pool; the liquid deodorant is any one or more combinations of ricinoleic acid zinc salt and soybean oleate; the mass addition amount of the liquid deodorant in water does not exceed 5‰.

[0053] The fifth step is to raise the temperature again; set the screw speed and barrel temperature of the extruder C, and the dried rubber material enters the hopper of the extruder C, and is heated again to soften the rubber material again, and is discharged into the extruder D; the extruder C is a single-screw extruder, a twin-screw extruder, a three-screw extruder or a planetary screw extruder;

[0054] The extruder C has an aspect ratio of 40-50:1, a screw shear length that accounts for no less than 25% of the total screw length, a rotation speed of 60-100 rpm, a barrel heating temperature of 240-280°C, and a rubber residence time of no less than 30s.

[0055] The sixth step is thermal degradation; the screw speed and barrel temperature of the extruder D are set to perform thermal degradation, the deodorant reacts to deodorize, a vacuum device is used in the middle and end of the extruder to extract by-products to reduce the odor, and the rubber enters the cooling device; the extruder D is a twin-screw extruder, a three-screw extruder or a planetary screw extruder with both shearing and conveying functions;

[0056] The extruder D has an aspect ratio of 40 to 60:1, a screw meshing element length of not less than 30% of the total screw length, a shear element length of not less than 15% of the total screw length, a rotation speed of 35 to 140 rpm, a barrel heating temperature of 280 to 350°C, and a rubber residence time of not less than 100 s.

[0057] The seventh step is cooling and debonding. The parameters of the cooling device are set. After the rubber material is cooled by the cooling device, the final debonding temperature is controlled, and the liquid rubber product is finally discharged and collected. The cooling device is one or two of a screw extruder and a stirring tank that can provide cooling effect to the rubber material. The cooling effect of the cooling device is: within a cooling time of 60s, the final debonding temperature of the rubber material is less than 100℃.

[0058] The deodorizing mechanism and process used in the present invention mainly include:

[0059] 1) The deodorant added in the mixing stage reacts fully with the generated odor molecules in the extruder A during the mixing stage and adsorbs them; effectively removing the odor generated by proteins in natural rubber, acetone extracts, synthetic rubber solvents, etc.;

[0060] 2) In extruders B and C, under the condition of constant viscosity, the pores of the deodorant carrier are prevented from being blocked and inactivated, and continue to react and adsorb with the newly generated odor molecules;

[0061] 3) In the water cooling deodorization stage, the rubber is cooled by 50-60℃ warm water with liquid deodorizer added, while the liquid deodorizer and the odor molecules that were not completely removed in the previous step are extracted;

[0062] 4). In extruder D, the residual odor molecules and those generated in this stage are vacuum-extracted at high temperature by heating at 280-360°C, and the odor of liquid rubber is finally removed;

[0063] 5). The viscosity of the rubber compound in the discharge stage is effectively reduced compared to that in extruder B, and a small amount of residual odor molecules are effectively sealed so that they do not escape during subsequent use.

[0064] The beneficial effects of the present invention are:

[0065] Taking advantage of the extruder's advantages such as uniform thermal shearing, high efficiency, and precise temperature control, liquid rubber is prepared by thermal degradation. High shearing is first used to break the macromolecular chains at low temperatures, and then high temperature is used to provide energy to continuously break the main chain.

[0066] The liquid rubber product obtained by the present invention has similar performance to conventional liquid rubber on the market; compared with the synthesis method, no solvent is used, and the requirements for reaction conditions are easier to achieve than the synthesis method; a screw extruder is used for preparation, and the preparation process has the characteristics of high efficiency, continuity, environmental protection, easy scale-up and industrialization; compared with the traditional screw extrusion method, the product has no odor.

[0067] Example 1

[0068] a. Raw material mixing stage: The mixture of NR raw rubber, deodorant, antioxidant, peptizer and activator is mixed in the mixing device, the discharge temperature is controlled at 110-120℃ and the Mooney viscosity is 45-65, and the mixed rubber is discharged into the extruder A;

[0069] b. Low-temperature deodorization stage: set the screw speed of extruder A to 80 rpm and the barrel temperature to 160°C, break the macromolecular chain by shearing, and the deodorant in the rubber compound reacts and deodorizes;

[0070] c. Heating and softening stage: set the screw speed of extruder B to 70rpm and the barrel temperature to 240℃, the rubber is heated and softened, the deodorant in the mixed rubber continues to react and deodorize, a vacuum device is used at the end of the extruder to extract by-products to reduce the odor, the sheet is discharged from the die head and discharged into a pool of 50-60℃ warm water;

[0071] d. Water cooling and deodorization stage: The rubber material is discharged into the water pool through the extruder B, soaked for 1 minute and then dried to remove the residual odor caused by the heating chain breaking reaction during the heating and softening stage;

[0072] e. Reheating stage: set the screw speed of extruder C to 70rpm and the barrel temperature to 240℃, the dried rubber enters the hopper of extruder C, and is reheated to soften the rubber again and discharged into extruder D;

[0073] f. Thermal degradation stage: set the screw speed of extruder D to 50rpm and the barrel temperature to 300℃ for thermal degradation, the deodorant reacts to remove odor, a vacuum device is used in the middle and end of the extruder to extract by-products to reduce odor, and the rubber enters the cooling device;

[0074] g. Cooling and degumming stage: Set the parameters of the cooling device, cool the rubber through the device, control the final degumming temperature, and finally discharge and collect the liquid rubber product.

[0075] Finally, a liquid natural rubber having a number average molecular weight Mn of 107942 and being completely soluble in toluene was obtained.

[0076] Example 2

[0077] a. Raw material mixing stage: The mixture of NR raw rubber, deodorant, antioxidant, peptizer and activator is mixed in the mixing device, the discharge temperature is controlled at 110-120℃ and the Mooney viscosity is 45-65, and the mixed rubber is discharged into the extruder A;

[0078] b. Low-temperature deodorization stage: set the screw speed of extruder A to 80 rpm and the barrel temperature to 160°C, break the macromolecular chain by shearing, and the deodorant in the rubber compound reacts and deodorizes;

[0079] c. Heating and softening stage: set the screw speed of extruder B to 70rpm and the barrel temperature to 250℃, the rubber is heated and softened, the deodorant in the mixed rubber continues to react and deodorize, a vacuum device is used at the end of the extruder to extract by-products to reduce the odor, the sheet is discharged from the die head and discharged into a pool of 50-60℃ warm water;

[0080] d. Water cooling and deodorization stage: The rubber material is discharged into the water pool through the extruder B, soaked for 1 minute and then dried to remove the residual odor caused by the heating chain breaking reaction during the heating and softening stage;

[0081] e. Reheating stage: set the screw speed of extruder C to 75rpm and the barrel temperature to 250℃, the dried rubber enters the hopper of extruder C, and is reheated to soften the rubber again and discharged into extruder D;

[0082] f. Thermal degradation stage: set the screw speed of extruder D to 45rpm and the barrel temperature to 320℃ for thermal degradation, the deodorant reacts to remove odor, a vacuum device is used in the middle and end of the extruder to extract by-products to reduce odor, and the rubber enters the cooling device;

[0083] g. Cooling and degumming stage: Set the parameters of the cooling device, cool the rubber through the device, control the final degumming temperature, and finally discharge and collect the liquid rubber product.

[0084] Finally, a liquid natural rubber having a number average molecular weight Mn of 56791 and being completely soluble in toluene was obtained.

[0085] Example 3

[0086] a. Raw material mixing stage: The mixture of NR raw rubber, deodorant, antioxidant, peptizer and activator is mixed in the mixing device, the discharge temperature is controlled at 110-120℃ and the Mooney viscosity is 45-65, and the mixed rubber is discharged into the extruder A;

[0087] b. Low-temperature deodorization stage: set the screw speed of extruder A to 80 rpm and the barrel temperature to 170°C, break the macromolecular chain by shearing, and the deodorant in the rubber compound reacts and deodorizes;

[0088] c. Heating and softening stage: set the screw speed of extruder B to 70rpm and the barrel temperature to 260℃, the rubber is heated and softened, the deodorant in the mixed rubber continues to react and deodorize, a vacuum device is used at the end of the extruder to extract by-products to reduce the odor, the sheet is discharged from the die head and discharged into a pool of 50-60℃ warm water;

[0089] d. Water cooling and deodorization stage: The rubber material is discharged into the water pool through the extruder B, soaked for 1 minute and then dried to remove the residual odor caused by the heating chain breaking reaction during the heating and softening stage;

[0090] e. Reheating stage: Set the screw speed of extruder C to 75rpm and the barrel temperature to 260℃. The dried rubber enters the hopper of extruder C and is reheated to soften the rubber again and then discharged into extruder D.

[0091] f. Thermal degradation stage: set the screw speed of extruder D to 45rpm and the barrel temperature to 340℃ for thermal degradation, the deodorant reacts to remove odor, a vacuum device is used in the middle and end of the extruder to extract by-products to reduce odor, and the rubber enters the cooling device;

[0092] g. Cooling and degumming stage: Set the parameters of the cooling device, cool the rubber through the device, control the final degumming temperature, and finally discharge and collect the liquid rubber product.

[0093] Finally, a liquid natural rubber having a number average molecular weight Mn of 33624 and being completely soluble in toluene was obtained.

[0094] Example 4

[0095] a. Raw material mixing stage: The mixture of NR raw rubber, deodorant, antioxidant, peptizer and activator is mixed in the mixing device, the discharge temperature is controlled at 110-120℃ and the Mooney viscosity is 45-65, and the mixed rubber is discharged into the extruder A;

[0096] b. Low-temperature deodorization stage: set the screw speed of extruder A to 80 rpm and the barrel temperature to 170°C, break the macromolecular chain by shearing, and the deodorant in the rubber compound reacts and deodorizes;

[0097] c. Heating and softening stage: set the screw speed of extruder B to 70rpm and the barrel temperature to 270℃, the rubber is heated and softened, the deodorant in the mixed rubber continues to react and deodorize, a vacuum device is used at the end of the extruder to extract by-products to reduce the odor, the sheet is discharged from the die head and discharged into a pool of 50-60℃ warm water;

[0098] d. Water cooling and deodorization stage: The rubber material is discharged into the water pool through the extruder B, soaked for 1 minute and then dried to remove the residual odor caused by the heating chain breaking reaction during the heating and softening stage;

[0099] e. Reheating stage: set the screw speed of extruder C to 60rpm and the barrel temperature to 270℃, the dried rubber enters the hopper of extruder C, and is reheated to soften the rubber again and discharged into extruder D;

[0100] f. Thermal degradation stage: set the screw speed of extruder D to 45rpm and the barrel temperature to 350℃ for thermal degradation, the deodorant reacts to remove odor, a vacuum device is used in the middle and end of the extruder to extract by-products to reduce odor, and the rubber enters the cooling device;

[0101] g. Cooling and degumming stage: Set the parameters of the cooling device, cool the rubber through the device, control the final degumming temperature, and finally discharge and collect the liquid rubber product.

[0102] Finally, a liquid natural rubber having a number average molecular weight Mn of 22781 and being completely soluble in toluene was obtained.

[0103] Example 5

[0104] a. Raw material mixing stage: The mixture of NR raw rubber, deodorant, antioxidant, peptizer and activator is mixed in the mixing device, the discharge temperature is controlled at 110-120℃ and the Mooney viscosity is 45-65, and the mixed rubber is discharged into the extruder A;

[0105] b. Low-temperature deodorization stage: set the screw speed of extruder A to 80 rpm and the barrel temperature to 180°C, break the macromolecular chain by shearing, and the deodorant in the rubber compound reacts and deodorizes;

[0106] c. Heating and softening stage: set the screw speed of extruder B to 60rpm and the barrel temperature to 280℃, the rubber is heated and softened, the deodorant in the mixed rubber continues to react and deodorize, a vacuum device is used at the end of the extruder to extract by-products to reduce the odor, the sheet is discharged from the die head and discharged into a pool of 50-60℃ warm water;

[0107] d. Water cooling and deodorization stage: The rubber material is discharged into the water pool through the extruder B, soaked for 1 minute and then dried to remove the residual odor caused by the heating chain breaking reaction during the heating and softening stage;

[0108] e. Reheating stage: set the screw speed of extruder C to 60rpm and the barrel temperature to 280℃, the dried rubber enters the hopper of extruder C, and is reheated to soften the rubber again and discharged into extruder D;

[0109] f. Thermal degradation stage: set the screw speed of extruder D to 45rpm and the barrel temperature to 360℃ for thermal degradation, the deodorant reacts to remove odor, a vacuum device is used in the middle and end of the extruder to extract by-products to reduce odor, and the rubber enters the cooling device;

[0110] g. Cooling and degumming stage: Set the parameters of the cooling device, cool the rubber through the device, control the final degumming temperature, and finally discharge and collect the liquid rubber product.

[0111] Finally, a liquid natural rubber having a number average molecular weight of Mn 9752 and being completely soluble in toluene was obtained.

[0112] Example 6

[0113] a. Raw material mixing stage: The mixture of SBR raw rubber, antioxidant, peptizer and activator is mixed in the mixing device, the discharge temperature is controlled at 110-120℃ and the Mooney viscosity is 45-65, and the mixed rubber is discharged into the extruder A;

[0114] b. Low-temperature deodorization stage: set the screw speed of extruder A to 80 rpm and the barrel temperature to 180°C to break the macromolecular chains by shearing;

[0115] c. Heating and softening stage: set the screw speed of extruder B to 60rpm and the barrel temperature to 280℃, the rubber compound is heated and softened, a vacuum device is used at the end of the extruder to extract by-products to reduce odor, and the sheets are discharged from the die head into a pool of 50-60℃ warm water;

[0116] d. Water cooling and deodorization stage: The rubber material is discharged into the water pool through the extruder B, soaked for 1 minute and then dried to remove the residual odor caused by the heating chain breaking reaction during the heating and softening stage;

[0117] e. Reheating stage: set the screw speed of extruder C to 60rpm and the barrel temperature to 280℃, the dried rubber enters the hopper of extruder C, and is reheated to soften the rubber again and discharged into extruder D;

[0118] f. Thermal degradation stage: set the screw speed of extruder D to 45rpm and the barrel temperature to 360℃ for thermal degradation, the deodorant reacts to remove odor, a vacuum device is used in the middle and end of the extruder to extract by-products to reduce odor, and the rubber enters the cooling device;

[0119] g. Cooling and degumming stage: Set the parameters of the cooling device, cool the rubber through the device, control the final degumming temperature, and finally discharge and collect the liquid rubber product.

[0120] Finally, a liquid styrene-butadiene rubber with a number average molecular weight of Mn 13582 that is completely soluble in toluene is obtained. The serial numbers of the above embodiments of the present invention are only for description and do not represent the advantages and disadvantages of the embodiments. Through the above description of the 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, it can also be implemented by simplifying some important technical features. Based on this understanding, the technical solution of the present invention is essentially or the part that contributes to the prior art is: the overall structure and connection method, and the structure described in each embodiment of the present invention.

[0121] 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 odorless liquid rubber, characterized in that: The following steps are involved: The first step is to mix the raw materials; mix the raw rubber, deodorant, antioxidant, peptizer and activator in a mixing device, control the discharge temperature and Mooney viscosity, and discharge the mixed rubber produced by the mixing device into the extruder A; The second step is low-temperature deodorization; the screw speed and barrel temperature of extruder A are set to break the macromolecular chains of the mixed rubber by shearing, so that the deodorant reacts with the mixed rubber to deodorize; the mixed rubber in extruder A is discharged from extruder B; The third step is heating and softening. The screw speed and barrel temperature of extruder B are set, the rubber compound is heated and softened, and the deodorant in the rubber compound continues to react and deodorize. A vacuum device is used at the end of extruder B to extract by-products to reduce the odor, and the rubber compound in sheets is discharged from the die head. The fourth step is water cooling and deodorization. The rubber material is placed in a pool of warm water at 50-60℃, soaked in the pool for 1 minute and then dried to remove the residual odor caused by the chain breaking reaction during the heating and softening process. Step 5: Heating again; setting the screw speed and barrel temperature of extruder C, the dried rubber material enters the hopper of extruder C, and heating again to soften the rubber material again, and then discharges it into extruder D; Step 6: thermal degradation; set the screw speed and barrel temperature of extruder D to perform thermal degradation, the deodorant reacts to remove odor, a vacuum device is used in the middle and end of the extruder to extract by-products to reduce odor, and the rubber enters the cooling device; The seventh step is cooling and degumming. Set the parameters of the cooling device. After the rubber material is cooled by the cooling device, control the final degumming temperature, and finally discharge and collect the liquid rubber product.

2. The method for preparing odorless liquid rubber according to claim 1, characterized in that: The mixing device is any one or more types of internal mixers and open mixers connected in series; the Mooney viscosity of the mixing device is 45-65, and the temperature of the rubber material is 110-120°C.

3. The method for preparing odorless liquid rubber according to claim 1, characterized in that: The raw rubber includes any one or more of natural rubber, eucommia rubber, isoprene rubber, butadiene rubber, styrene-butadiene rubber, nitrile rubber and SBS; The deodorant is a mixture of at least one of inorganic carbonate and nano titanium dioxide and polyacrylate; the mass ratio of inorganic carbonate and / or nano titanium dioxide to polyacrylate is 1:1-3; The antioxidant is any one or more of antioxidant 4020, antioxidant 4010NA, antioxidant 2246, and antioxidant RD; The peptizer is any one or more of peptizers A82, A86, A60, and HT105; The activator is an alkyl disulfide; The mass ratio of the raw rubber, the deodorant, the antioxidant, the peptizer and the activator is 1000:0-3.5:10-30:0-30:0-100.

4. The method for preparing odorless liquid rubber according to claim 1, characterized in that: The extruder A is a twin-screw extruder, a triple-screw extruder or a planetary screw extruder; The extruder A has an aspect ratio of 40-50:1, the length of the screw shearing element accounts for no less than 30% of the total screw length, the rotation speed is 70-100rpm, the barrel heating temperature is 160-180°C, and the rubber residence time is no less than 50s.

5. The method for preparing odorless liquid rubber according to claim 1, characterized in that: The extruder B is a single screw extruder, a twin screw extruder, a triple screw extruder or a planetary screw extruder with enhanced shearing effect; The extruder B has an aspect ratio of 40-50:1, the length of the screw shearing element accounts for no less than 25% of the total screw length, the rotation speed is 60-100rpm, the barrel heating temperature is 240-280°C, and the rubber residence time is no less than 60s.

6. The method for preparing odorless liquid rubber according to claim 1, characterized in that: During the water cooling deodorization process, a liquid deodorant needs to be added to the water pool; the liquid deodorant is any one or more combinations of ricinoleic acid zinc salt and soybean oleate; the mass addition amount of the liquid deodorant in the water does not exceed 5‰.

7. The method for preparing odorless liquid rubber according to claim 1, characterized in that: The extruder C is a single screw extruder, a twin screw extruder, a triple screw extruder or a planetary screw extruder; The extruder C has an aspect ratio of 40-50:1, a screw shear length that accounts for no less than 25% of the total screw length, a rotation speed of 60-100 rpm, a barrel heating temperature of 240-280°C, and a rubber residence time of no less than 30s.

8. The method for preparing odorless liquid rubber according to claim 1, characterized in that: The extruder D is a twin-screw extruder, a three-screw extruder or a planetary screw extruder having both shearing and conveying functions; The extruder D has an aspect ratio of 40 to 60:1, a screw meshing element length of not less than 30% of the total screw length, a shear element length of not less than 15% of the total screw length, a rotation speed of 35 to 140 rpm, a barrel heating temperature of 280 to 350°C, and a rubber residence time of not less than 100 s.

9. The method for preparing odorless liquid rubber according to claim 1, characterized in that: The cooling device is one or two of a screw extruder and a stirring tank connected in series, which can provide cooling effect for the rubber material; the cooling effect of the cooling device is that within a cooling time of 60 seconds, the final discharge temperature of the rubber material is less than 100°C.