CN108659147B - Physical dehydration method of natural latex - Google Patents
Physical dehydration method of natural latex Download PDFInfo
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- CN108659147B CN108659147B CN201810538297.5A CN201810538297A CN108659147B CN 108659147 B CN108659147 B CN 108659147B CN 201810538297 A CN201810538297 A CN 201810538297A CN 108659147 B CN108659147 B CN 108659147B
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08C—TREATMENT OR CHEMICAL MODIFICATION OF RUBBERS
- C08C1/00—Treatment of rubber latex
- C08C1/02—Chemical or physical treatment of rubber latex before or during concentration
- C08C1/075—Concentrating
- C08C1/12—Concentrating by evaporation
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- Chemical Kinetics & Catalysis (AREA)
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- Processes Of Treating Macromolecular Substances (AREA)
- Processing And Handling Of Plastics And Other Materials For Molding In General (AREA)
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Abstract
The invention provides a physical dehydration method of natural latex, which comprises the following steps: putting the natural latex into a vacuum drying oven, vacuumizing to 0.05-0.1 MPa of negative pressure, controlling the temperature to 50-80 ℃, exhausting generated water vapor out of the vacuum drying oven by exhausting air and dehumidifying, and taking out the natural latex after vacuum drying and dehydrating for 1-12 hours. The invention utilizes the low-temperature, vacuum, air exhaust and dehumidifying dehydration method, not only efficiently and fully dehydrates the natural latex, reduces the difficulty of the subsequent secondary dehydration, improves the efficiency of the secondary dehydration, but also avoids the occurrence of the half-cooked condition, avoids the loss of natural components and the breakage of molecular chains in the natural latex during the dehydration process, improves the thermo-oxidative aging resistance, and the performance of the prepared natural rubber is superior to that of the full latex of the traditional process. In addition, the physical dehydration method of the natural latex has simple process flow, can realize continuous production and improve the efficiency of preparing high-quality natural rubber.
Description
Technical Field
The invention relates to the technical field of natural rubber, in particular to a physical dehydration method of natural latex.
Background
The natural rubber has a series of physicochemical properties, particularly excellent characteristics such as rebound resilience, insulativity, water resistance and plasticity, and has precious properties such as oil resistance, acid resistance, alkali resistance, heat resistance, cold resistance, pressure resistance and wear resistance after being properly treated, so the natural rubber has wide application. Such as rain shoes, hot water bags, elastic bands used in daily life; surgeon gloves, blood delivery tubes, condoms used in the medical and health industry; various tires used in transportation; conveyor belts, acid and base resistant gloves used in industry; drainage and irrigation rubber tubes and ammonia water bags used in agriculture; sounding balloons for meteorological measurements; sealing and shockproof equipment for scientific experiments; airplanes, tanks, cannons and gas masks used in national defense; even high-precision scientific and technical products such as rockets, artificial earth satellites and spacecrafts can not be separated from natural rubber. Natural rubber latex is dehydrated to produce natural rubber. The original natural latex dehydration process adopts acid coagulation dehydration and crumpling machine extrusion dehydration, so that loss of natural components in natural rubber can be caused, molecular chains are broken, the tensile strength of a product is low, the thermal-oxidative aging resistance is poor, the dehydration degree is not enough, the water content of the natural rubber is still 35-40% after the dehydration by the traditional process, the drying difficulty is increased, the undercooking condition can occur, the product performance is unstable, and the quality of the natural rubber is influenced; the traditional process has long dehydration time and low efficiency, so that the production cannot be continuous; therefore, a physical dehydration method of natural latex is urgently needed to solve the technical problems.
Disclosure of Invention
Therefore, the invention provides a physical dehydration method of natural latex, which can efficiently and fully dehydrate the natural latex, improve the efficiency of secondary dehydration, improve the thermo-oxidative aging resistance and improve the tensile strength of the natural latex.
The technical scheme of the invention is realized as follows:
a physical dehydration method of natural latex comprises the following steps: putting the natural latex into a vacuum drying oven, vacuumizing to 0.05-0.1 MPa of negative pressure, controlling the temperature to 50-80 ℃, exhausting generated water vapor out of the vacuum drying oven by exhausting air and dehumidifying, and taking out the natural latex after vacuum drying and dehydrating for 1-12 hours.
Further, before vacuum dehydration, a drying agent is put into a vacuum drying oven, wherein the drying agent is a molecular sieve and montmorillonite mixed drying agent, and the mass ratio of the molecular sieve to the montmorillonite is 1 (1-2).
Further, the natural latex is taken out and then placed in a double-screw extruder for secondary dehydration.
Further, the temperature is 60-75 ℃.
Further, the dehydration time is 3-5 hours.
Further, vacuumizing to a negative pressure of 0.07 MPa-0.09 MPa.
Further, the mass ratio of the molecular sieve to the montmorillonite is 1: 2.
Further, the temperature was 75 ℃.
Furthermore, the heating mode of the vacuum drying box is a hot water circulation heating mode.
Furthermore, a plurality of layers of movable heating drying frames are arranged in the vacuum drying oven.
Compared with the prior art, the invention has the beneficial effects that: the physical dehydration method of natural latex of the invention utilizes low temperature, vacuum, air exhaust and dehumidifying dehydration methods, not only efficiently and fully dehydrates the natural latex, reduces the difficulty of secondary dehydration later and improves the efficiency of secondary dehydration, but also avoids the occurrence of half-cooked condition, avoids the loss of natural components and the breakage of molecular chains in the natural latex during dehydration, improves the thermo-oxidative aging resistance, and the performance of the prepared natural rubber is superior to the full latex of the traditional process. The dehydration temperature set by the invention not only has good dehydration effect, but also promotes the molding of the natural rubber, so that the prepared natural rubber has excellent tensile strength; the vacuum-pumping negative pressure arranged in the invention not only promotes dehydration, but also is beneficial to enhancing the performance; the multi-layer movable heating drying rack is convenient for placing natural latex, promoting uniform heating and being convenient for dismantling and cleaning; the invention adopts a hot water circulation heating mode, and can further improve the dehydration efficiency. In addition, the physical dehydration method of the natural latex has simple process flow, can realize continuous production and improve the efficiency of preparing high-quality natural rubber.
Detailed Description
In order to better understand the technical content of the invention, specific examples are provided below to further illustrate the invention.
Example 1
A physical dehydration method of natural latex comprises the following steps:
before vacuum dehydration, a drying agent is put into a vacuum drying box, wherein the drying agent is a mixed drying agent of a molecular sieve and montmorillonite, and the mass ratio of the molecular sieve to the montmorillonite is 1: 1;
putting natural latex into a heating plate, placing the natural latex on a movable heating drying frame in a vacuum drying oven, vacuumizing to 0.1MPa of negative pressure, controlling the temperature to 50 ℃, performing air suction and dehumidification in the box body through a vacuum pump of the vacuum drying oven, discharging generated water vapor out of the vacuum drying oven, performing vacuum drying and dehydration for 12 hours, taking out the natural latex to obtain dehydrated natural latex, and performing dehydration, wherein the natural latex is in a transition state from a viscous state to a solidified state;
after vacuum drying, the natural latex is taken out and placed in a double-screw extruder for secondary dehydration to prepare the natural rubber.
Example 2
A physical dehydration method of natural latex comprises the following steps:
before vacuum drying, a drying agent is put into a vacuum drying oven, wherein the drying agent is a mixed drying agent of a molecular sieve and montmorillonite, and the mass ratio of the molecular sieve to the montmorillonite is 1: 2;
putting natural latex into a heating plate, placing the natural latex on a movable heating drying frame in a vacuum drying oven, vacuumizing to 0.05MPa of negative pressure, controlling the temperature to 80 ℃, performing air suction and dehumidification in the box body through a vacuum pump of the vacuum drying oven, discharging generated water vapor out of the vacuum drying oven, performing vacuum drying and dehydration for 1 hour, taking out the natural latex to obtain the dehydrated natural latex, and performing dehydration, wherein the natural latex is in a transition state from a viscous state to a solidified state.
After vacuum drying, the natural latex is taken out and placed in a double-screw extruder for secondary dehydration to prepare the natural rubber.
Example 3
A physical dehydration method of natural latex comprises the following steps:
before vacuum drying, a drying agent is put into a vacuum drying oven, wherein the drying agent is a mixed drying agent of a molecular sieve and montmorillonite, and the mass ratio of the molecular sieve to the montmorillonite is 1: 2;
putting natural latex into a heating plate, placing the natural latex on a movable heating drying frame in a vacuum drying oven, vacuumizing to 0.08MPa of negative pressure, controlling the temperature to 75 ℃, performing air suction and dehumidification in the box body through a vacuum pump of the vacuum drying oven, discharging generated water vapor out of the vacuum drying oven, performing vacuum drying and dehydration for 3 hours, taking out the natural latex to obtain dehydrated natural latex, and performing dehydration, wherein the natural latex is in a transition state from a viscous state to a solidified state.
After vacuum drying, the natural latex is taken out and placed in a double-screw extruder for secondary dehydration to prepare the natural rubber.
Example 4
This example differs from example 3 in that the vacuum is applied to a negative pressure of 0.09MPa, the dehydration temperature is 60 ℃ and the dehydration time is 5 hours.
Example 5
This example differs from example 3 in that the vacuum is applied to a negative pressure of 0.07MPa, the dehydration temperature is 75 ℃ and the time is 3 hours.
Example 6
The present implementation differs from example 3 in that the mass ratio of the molecular sieve to the montmorillonite is 1: 1.
Example 7
The difference between this example and example 3 is that no desiccant was added before vacuum drying.
Comparative example 1
This comparative example differs from example 3 in that the dehydration temperature is 90 ℃.
Comparative example 2
This comparative example differs from example 3 in that the vacuum was applied to a negative pressure of 0.04 MPa.
The vacuum drying oven is internally provided with the multi-layer movable heating drying rack, so that natural latex can be placed conveniently, uniform heating is promoted, and the vacuum drying oven is convenient to disassemble and clean. The heating mode of the vacuum drying box is a hot water circulation heating mode, so that the dehydration efficiency can be further improved.
The water content of the dehydrated natural rubber latex is tested by adopting the examples 1-7 and the comparative examples 1-2 of the invention, and the tensile strength performance of the natural rubber (full latex) prepared by the examples 1-7 and the comparative examples 1-2 of the invention and the traditional process is tested after mixing, and the formula (quality) of mixing is as follows: 100 parts of natural rubber, 6 parts of zinc oxide, 0.5 part of stearic acid, 0.5 part of accelerator M and 3.5 parts of sulfur; the vulcanization conditions are as follows: 140 ℃ for 25 min; wherein the tensile strength is tested according to GB/T528-2009; the test results were as follows:
the results show that the natural rubber dehydration method has good dehydration effect, can efficiently remove a large amount of water in the natural rubber latex by using the vacuum dehydration method, and adopts a double-screw extruder to dehydrate so as to basically remove the water, so that the prepared natural rubber has the performance which is obviously superior to that of the full latex prepared by the traditional process. And the prepared natural rubber has good tensile strength performance. Among them, the dewatering effect and tensile strength property of example 3 are the best, indicating that the dewatering process of example 3 is the best; compared with the example 3, the temperature is too high, the dehydration tensile strength is poor, the moisture removal effect is not as good as that of the example 3, and the dehydration temperature set by the invention is good in dehydration effect, promotes the forming of the product and has excellent tensile strength; compared with the example 2, the negative pressure is insufficient, the dehydration effect is poor, and the tensile strength is much lower than that of the example 3, which shows that the vacuum-pumping negative pressure provided by the invention not only promotes the dehydration, but also is beneficial to enhancing the performance.
In conclusion, the physical dehydration method of natural latex of the invention utilizes low-temperature, vacuum, air extraction and dehumidifying dehydration methods, which not only effectively and fully dehydrates the natural latex, reduces the difficulty of the subsequent secondary dehydration, improves the efficiency of the secondary dehydration, but also avoids the occurrence of half-cooked condition, avoids the loss of natural components and the breakage of molecular chains in the natural latex during the dehydration process, improves the thermo-oxidative aging resistance and improves the tensile strength of the prepared natural rubber. The dehydration temperature set by the invention not only has good dehydration effect, but also promotes the molding of the natural rubber, so that the prepared natural rubber has excellent tensile strength; the vacuum-pumping negative pressure arranged in the invention not only promotes dehydration, but also is beneficial to enhancing the performance; the multi-layer movable heating drying rack is convenient for placing natural latex, promoting uniform heating and being convenient for dismantling and cleaning; the invention adopts a hot water circulation heating mode, and can further improve the dehydration efficiency. In addition, the physical dehydration method of the natural latex has simple process flow, can realize continuous production and improve the efficiency of preparing high-quality natural rubber.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (8)
1. A physical dehydration method of natural latex is characterized in that: the method comprises the following steps: and (2) putting the natural latex into a vacuum drying oven, vacuumizing to 0.07-0.09 MPa of negative pressure, controlling the temperature to 60-75 ℃, exhausting generated water vapor out of the vacuum drying oven by exhausting air and dehumidifying, and taking out the natural latex after vacuum drying and dehydrating for 1-12 hours.
2. The physical dehydration process of natural latex according to claim 1, characterized by the fact that: before vacuum dehydration, a drying agent is put into a vacuum drying box, wherein the drying agent is a mixed drying agent of a molecular sieve and montmorillonite, and the mass ratio of the molecular sieve to the montmorillonite is 1 (1-2).
3. A process for the physical dehydration of natural latex according to claim 1 or 2, characterized by: and taking out the natural latex, putting the natural latex into a double-screw extruder, and performing secondary dehydration.
4. A process for the physical dehydration of natural latex according to claim 1 or 2, characterized by: the dehydration time is 3-5 hours.
5. The physical dehydration process of natural latex according to claim 2, characterized by the fact that: the mass ratio of the molecular sieve to the montmorillonite is 1: 2.
6. The physical dehydration process of natural latex according to claim 1, characterized by the fact that: the temperature was 75 ℃.
7. A process for the physical dehydration of natural latex according to claim 1 or 2, characterized by: the heating mode of the vacuum drying box is a hot water circulation heating mode.
8. A process for the physical dehydration of natural latex according to claim 1 or 2, characterized by: and a plurality of layers of movable heating drying frames are arranged in the vacuum drying box.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201810538297.5A CN108659147B (en) | 2018-05-30 | 2018-05-30 | Physical dehydration method of natural latex |
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| CN201810538297.5A CN108659147B (en) | 2018-05-30 | 2018-05-30 | Physical dehydration method of natural latex |
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| CN108659147A CN108659147A (en) | 2018-10-16 |
| CN108659147B true CN108659147B (en) | 2020-07-03 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| GB436536A (en) * | 1934-03-16 | 1935-10-14 | Metallgesellschaft Ag | Improvements in or relating to the concentration of latices |
| CN102477109A (en) * | 2010-11-22 | 2012-05-30 | 蒋盛军 | Method for promoting natural rubber latex to coagulate in vacuum |
| CN102690374A (en) * | 2012-06-04 | 2012-09-26 | 辽宁和运合成橡胶研究院有限公司 | Method for comprehensively drying liquid rubber and drying device |
| CN103087220B (en) * | 2013-01-23 | 2014-10-15 | 黄润燕 | Method for deodorizing and extracting proteins in processing of natural rubber latex |
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