Extraction method of plant rubber and plant rubber

Abstract

The invention relates to a plant rubber extraction method, which comprises: grinding a plant rubber-containing raw material for 1-20 times to obtain a first pretreatment material; sieving the first pretreated object to obtain a second pretreated object remained on a screen; and taking the second pretreated material as a grinding raw material, repeating the previous grinding and sieving operations for more than 3 times, and finally obtaining the plant rubber. According to the invention, the plant rubber can be extracted from the plant tissues only by using the raw materials, the grinding unit and the separating sieve. On one hand, the use of an organic solvent with certain toxicity is avoided, and no pollution is caused to the environment; on the other hand, the extraction rate of the plant rubber is at least 80% and is far higher than that in the prior art.

Description

Technical Field

[0001] The present invention relates to the technical field of plant rubber extraction, and more particularly to a plant rubber extraction method and the plant rubber. Background Art

[0002] With the continuous innovation and revolution of industrial technology, the number of natural rubber products on the market is increasing, so the demand for natural rubber production is also increasing day by day. Natural rubber, petroleum, steel and coal are known as the four major industrial raw materials in the world. As one of the four major industrial raw materials, natural rubber is favored in all walks of life. This is because natural rubber has good elasticity and excellent mechanical properties at room temperature. At present, more than 80% of my country's natural rubber is imported, so finding a second natural rubber will be of great significance to my country's rubber industry. Although there are more than 2,000 plants that can produce natural rubber, most of them have a low rubber content.

[0003] Eucommia ulmoides is a plant unique to China, and more than 95% of the world's Eucommia ulmoides resources are in China. Eucommia ulmoides is also the world's most adaptable and high-quality gum source tree species with the greatest development potential. The leaves, bark and peel of Eucommia ulmoides are rich in a white filamentous substance, namely Eucommia ulmoides gum. Eucommia ulmoides gum is an excellent polymer material with the dual properties of rubber and plastic, and its main component is trans-polyisoprene. At present, its extraction technology mainly includes organic solvent extraction and fermentation extraction, but its extraction rate can only reach about 30%, which is not suitable for industrial application. In addition, the organic solvent in the organic solvent extraction method has certain toxicity, serious environmental pollution, and relatively high cost.

[0004] In view of this, developing a method that can improve the extraction rate of vegetable rubber has become an urgent issue for those skilled in the art. Summary of the invention

[0005] In view of the problems existing in the prior art, the purpose of the present invention is to provide a method for extracting vegetable rubber, which can extract vegetable rubber from plant tissues using only raw materials, a grinder and a separation tank, and the vegetable rubber extraction rate is at least 80%.

[0006] In order to solve the above technical problems, the present invention provides a method for extracting vegetable rubber, comprising the following steps:

[0007] S10: Detecting the water content of the raw material containing vegetable rubber;

[0008] S20: grinding the raw material containing vegetable rubber for 1 to 4 times to obtain a first pretreated product;

[0009] S30: screening the first pretreated product to obtain a second pretreated product;

[0010] S40: using the second pretreated product as a raw material for grinding, repeating steps S20 and S30 for more than 3 times to obtain vegetable rubber.

[0011] The extraction method of the present invention obtains a better extraction effect due to the use of grinding means. In the strong extrusion and kneading process of grinding, the non-colloid in the raw material will be continuously ground and the particle size will become smaller and smaller, while the colloid in the raw material will not change its particle size even if it is repeatedly ground due to its own viscosity and elasticity, so it will be more likely to remain on the screen when sieving, while the non-colloid with smaller particle size will pass through the screen and be sifted out. In addition, the reason why the sieving operation is interspersed between several grinding processes is that on the one hand, impurities can be removed as soon as possible to reduce the ineffective grinding of a large number of impurities, and on the other hand, it can avoid the heat generated by long-term grinding so that the colloid is melted, and the molten colloid will easily wrap the non-colloid in the colloid, making it difficult to improve the final colloid purity.

[0012] In a preferred embodiment of the present invention, in step S20, during grinding, the air pressure in the grinding equipment is greater than 101.325 kPa to prevent water vapor in the air from entering. If external water vapor enters the grinding equipment, it will freeze. On the one hand, ice crystals will increase the ineffective power consumption of grinding, and even freeze the grinding disc to cause the grinding equipment to malfunction. On the other hand, water vapor will continue to accumulate and remain in the raw material when it freezes. When sieving, the material becomes viscous as the ice crystals melt, thereby hindering the smooth progress of screening. Therefore, it is necessary to maintain the air pressure in the grinding equipment greater than 101.325 kPa. Preferably, any one of nitrogen, carbon dioxide, helium, neon, argon, krypton, xenon and radon can be introduced into the grinding equipment. The present invention continuously delivers a protective gas that maintains a positive pressure during the grinding process, so that the protective gas is blocked between the raw material and the outside air to avoid contact between the raw material and external water vapor. These gases will not affect the grinding of the raw material containing vegetable rubber, and can ensure that the air pressure in the grinding equipment is greater than 101.325 kPa, thereby achieving the purpose of preventing water vapor in the air from entering.

[0013] In a preferred embodiment of the present invention, the raw material containing vegetable rubber is any one of Eucommia ulmoides, dandelion, guayule, and Hevea brasiliensis. In another preferred embodiment of the present invention, in step S30, the mesh size of the sieve during sieving is 40 to 1000 mesh, preferably 200 to 400 mesh. The technician can select the appropriate mesh size of the sieve according to the actual situation (such as different raw materials containing vegetable rubber).

[0014] In a preferred embodiment of the present invention, when the water content of the raw material containing vegetable rubber is less than 15%, the temperature in the grinding equipment is -50°C to 10°C, preferably -30°C to -10°C. As the number of grindings increases, the temperature in the grinding equipment will gradually increase. By controlling the temperature in the grinding equipment to be lower than the glass transition temperature of the vegetable rubber, the colloid is prevented from gradually transforming into a glassy state and excessively entraining non-colloidal substances, which is convenient for the subsequent separation of the second pretreated product and is beneficial to the final purity improvement. In a more preferred embodiment of the present invention, the grinding equipment is provided with an interlayer, and any one of liquid nitrogen, liquid carbon dioxide, and ethanol is introduced into the interlayer to make the temperature in the grinding equipment -50°C to 10°C, preferably -30°C to -10°C. Specifically, a low-temperature coolant circulation pump can be used to circulate the liquid in the interlayer so that the temperature in the grinding equipment is maintained within a preset range.

[0015] In a preferred embodiment of the present invention, when the water content of the raw material containing vegetable rubber is ≥15%, in step S30,

[0016] S301: The first pretreated material is transferred to a screen;

[0017] S302: adding water to the first pretreated product;

[0018] S303: Screening to obtain a second pretreated product.

[0019] It should be noted that in step S302, adding water helps to transfer part of the first pre-treated material adhering to the grinding device after grinding to the screen, further improving the extraction rate of vegetable rubber. Preferably, the mass ratio of the first pre-treated material to water is 1: (1-15), preferably 1: (3-10). Water can be added to the first pre-treated material at one time or in several times.

[0020] In another preferred embodiment of the present invention, when the water content of the raw material containing vegetable rubber is ≥15%, in step S20,

[0021] S201: mixing the vegetable rubber with water;

[0022] S202: Grind the mixture containing vegetable rubber and water for 1 to 4 times to obtain a first pretreated product.

[0023] Preferably, the mass ratio of the first pretreated product to water is 1:(1-15), preferably 1:(3-10).

[0024] The present invention feeds the raw materials and water into the grinding equipment in a certain ratio. During the grinding process, the water will generate shear force due to its flow and scouring, so that a higher degree of separation is obtained between the colloid and the non-colloid. The raw material mixture with a ratio of 1: (1 to 15) not only obtains a relatively good hydraulic scouring and shearing effect, but also facilitates the improvement of the fluidity of the material during screening and improves the screening efficiency. However, if the amount of water added is further increased, the content of effective material per unit volume will be relatively small, which is not conducive to the extraction of colloid, and the proportion of useless work of the grinding device will increase during the grinding process, which is not conducive to energy saving and environmental protection.

[0025] The second object of the present invention is to provide a vegetable rubber obtained by the extraction method of the first object of the present invention, wherein the rubber content of the vegetable rubber is not less than 80%.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. The extraction method of the present invention can extract vegetable rubber from plant tissues using only raw materials, grinding equipment and separation equipment, or using some water. On the one hand, it avoids the use of organic solvents with certain toxicity and does not cause pollution to the environment; on the other hand, the extraction rate of vegetable rubber is at least 80%, which is much higher than the extraction rate of the prior art.

[0028] 2. The plant rubber obtained by the extraction method of the present invention is suitable for industrial application. Firstly, it can be used to make medical devices with not too bad service conditions, such as dental materials, prostheses, etc.; secondly, it can be used as raw materials and further separated and purified until the purity reaches 95%. In addition, the slag-water mixture discharged by the present invention can be used to make industrial fertilizers, realizing the comprehensive utilization of all parts of plants. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The schematic diagram of the structure of the mill for extracting vegetable rubber of the present invention;

[0030] Figure 2 The present invention is a schematic structural diagram of a grinding unit for extracting vegetable rubber.

[0031] Among them, 1-power device, 2-pulley shaft, 3-first grinder, 4-second grinder, 5-third grinder, 6-upper pulley, 7-belt, 8-lower pulley, 9-mill input shaft, 10-screw auger, 11-feeding port, 12-left grinding disc, 13-right grinding disc, 14-first pre-treated material discharge port, 15-middle interface. DETAILED DESCRIPTION

[0032] The present invention is described in detail below in conjunction with specific drawings and embodiments. It is necessary to point out that the following embodiments are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made to the present invention by those skilled in the art based on the content of the present invention still fall within the scope of protection of the present invention.

[0033] In the present invention, the raw material containing plant rubber is Eucommia bark, and its rubber content is about 6% to 10%. However, it should be noted that the method can also be applied to extracting plant rubber from other sources, such as extracting from rubber-containing plants such as dandelion, guayule or Hevea brasiliensis.

[0034] In the present invention, the water content is a mass fraction, that is, the percentage of the water content in the total weight of the raw material. Take a portion of the sample and weigh its weight m1; then dry it and weigh its dry weight m2; water content = (m1-m2) / m1.

[0035] Example 1

[0036] The mill used in this embodiment is as follows Figure 1 As shown, the mill input shaft 9 is fixedly connected to the spiral auger 10 arranged in the mill housing. Therefore, the mill input shaft 9 will rotate after the power is input to drive the spiral auger 10 to rotate, so that the horizontal direction of the material can be transmitted, so that the material entering from the feed port 11 on the upper side of the mill moves to the right side and then enters the grinding disc. The grinding disc includes two annular discs, namely Figure 1 The left grinding disc 12 and the right grinding disc 13 are shown in the figure. There are many strip-shaped protrusions between the left grinding disc 12 and the right grinding disc 13. The strip-shaped protrusions are only one of the embodiments of the present embodiment and do not constitute a limitation of the present invention. They can also be set as arc-shaped protrusions or abrasive particles. The abrasive particles here refer to the left grinding disc 12 and the right grinding disc 13, both of which are grinding wheels with many abrasive particles on the surface. Since the left grinding disc 12 is fixedly connected to the housing of the mill and the right grinding disc 13 is fixedly connected to the outer periphery of the spiral auger 10, the left grinding disc 12 is stationary and the right grinding disc 13 rotates under the drive of the spiral auger 10, so that the relative rotation of the left grinding disc 12 and the right grinding disc 13 is realized, and the purpose of grinding plant tissue is finally achieved. The left grinding disc 12 and the right grinding disc 13 are provided with an interlayer outside, and liquid nitrogen is introduced into the interlayer to reduce the temperature of the left grinding disc 12 and the right grinding disc 13. A first pre-treated material discharge port 14 is provided below the mill.

[0037] It should be noted that a power device is provided on the left side of the mill, a vibrating screen is provided below the mill (below the first pretreated material discharge port 14), a separation tank is provided below the vibrating screen, and the lower part of the mill is connected to the separation tank. Therefore, after grinding, the first pretreated material is transferred to the separation tank through the first pretreated material discharge port 14 under the vibration of the vibrating screen. Figure 1The power device and the vibrating screen are not shown in the figure, and the power device and the vibrating screen in the prior art can be used. An annular vertical net is arranged around the separation tank, and the annular vertical net is arranged vertically downward and surrounds the separation tank. The outside of the annular vertical net is an interlayer, and a stirring device is arranged inside. Under the stirring of the stirring device and the vibration of the vibrating screen, the non-colloidal material in the form of debris is transferred to the interlayer of the separation tank through the filter screen. The smaller the mesh number of the annular vertical net, the less the colloid loss; the larger the mesh number of the annular vertical net, the more the colloid loss. A valve is provided on one side of the interlayer of the separation tank, and the non-colloidal material in the form of debris can be discharged by opening the valve. A second pretreatment material discharge port and a valve are provided at the bottom of the separation tank, and the plant rubber mixed with some non-colloidal material in the form of debris can be transferred to the next mill by opening the valve.

[0038] The extraction method of the present embodiment is as follows:

[0039] Step 1: Detect the moisture content of the raw material containing vegetable rubber, and the moisture content is 14%. Because the moisture content of the raw material is not high, the raw material is directly dry-ground in the mill.

[0040] Step 2: 1 kg of raw material is fed into the mill from the feed port 11 and ground once to obtain the first pre-treated product. During grinding, the grinding environment temperature in the mill is controlled and the set temperature is -50°C. During the grinding process, since a vibrating screen is installed under the mill, the first pre-treated product after grinding is transferred to a separation tank.

[0041] Step 3: The first pre-treated material is sieved, and the mesh size is selected as 40 mesh. Since the particle size of the non-colloidal material becomes smaller under the action of grinding, the small particle size of the non-colloidal material is transferred to the interlayer of the separation tank through the filter screen under the action of stirring and vibration. The valve at the bottom of the separation tank is opened, and the second pre-treated material is transferred out through the second pre-treated material discharge port at the bottom of the separation tank, a total of 266.3g.

[0042] Step 4: Using the second pre-treated product as a raw material for grinding, repeat the above steps 2 and 3 for nine times, and finally obtain 22.1 g of vegetable rubber. The rubber content thereof is 80.3% as determined by the dissolution method.

[0043] Example 2

[0044] This embodiment uses the mill of embodiment 1, except that: in the mill of this embodiment, no interlayer is provided outside the left grinding disc 12 and the right grinding disc 13, and no temperature control of the grinding unit is required; and no vibrating screen is provided. The extraction method of this embodiment is as follows:

[0045] Step 1: Detect the moisture content of the raw material containing vegetable rubber, and the moisture content is 18%. Since the moisture content of the raw material is greater than 15%, wet grinding is used.

[0046] Step 2: 1 kg of raw material is fed into the mill from the feed port 11 and ground once at room temperature to obtain a first pre-treated product. Since the water content is relatively high and water has fluidity, the ground first pre-treated product can be automatically transferred to the separation tank under the action of gravity.

[0047] Step 3: Add water from the feed port 11, and the water flows to the separation tank. The amount of water is 10 kg, and the mass ratio of raw materials to water is 1:10. Add three times.

[0048] Step 4: Start the stirring device and sieve the first pre-treated product, the mesh number of which is 200. Under the action of stirring, the mixture of the non-colloidal and water in the form of slag is separated out of the separation tank, and the second pre-treated product (281.7 g) retained on the sieve is transferred out.

[0049] Step 5: Using the second pre-treated product as the raw material for grinding, repeat the above steps 3 and 4 for nine times, and finally obtain 35.9g of vegetable rubber. The rubber content thereof is 83.8% as determined by the dissolution method.

[0050] Example 3

[0051] This embodiment uses the mill of embodiment 1, except that: in the mill of this embodiment, no interlayer is provided outside the left grinding disc 12 and the right grinding disc 13, and no temperature control of the grinding unit is required; and no vibrating screen is provided. The extraction method of this embodiment is as follows:

[0052] Step 1: Detect the moisture content of the raw material containing vegetable rubber, and the moisture content is 18%. Since the moisture content of the raw material is greater than 15%, wet grinding is used.

[0053] Step 2: Mix 1 kg of raw material with water. The amount of water used is 10 kg, and the mass ratio of raw material to water is 1:10.

[0054] Step 3: Feed the mixture of raw materials and water into the mill from the feed port 11, grind once at room temperature to obtain the first pre-treated product. Since water has fluidity, the ground first pre-treated product can be automatically transferred to the separation tank under the action of gravity.

[0055] Step 4: Start the stirring device and sieve the first pre-treated product, the mesh number of which is 200. Under the action of stirring, the mixture of the non-colloidal and water in the form of slag is separated out of the separation tank, and the second pre-treated product (274.5 g) retained on the sieve is transferred out.

[0056] Step 5: Using the second pre-treated product as the raw material for grinding, repeat the above steps 3 and 4 for nine times, and finally obtain 34.7g of vegetable rubber. The rubber content thereof is 84.8% as determined by the dissolution method.

[0057] Example 4

[0058] The grinding machine group of this embodiment is as follows Figure 2 As shown by Figure 2 It can be seen that the leftmost side is a fixedly placed power device 1, and an output shaft is arranged on the right side thereof. Figure 2 The right side is respectively the first mill 3, the second mill 4 and the third mill 5 from top to bottom, which constitute a grinding machine group. It should be noted that the structures of the first mill 3, the second mill 4 and the third mill 5 are the same as those of the mill in Example 1. The left side of the first mill 3, the second mill 4 and the third mill 5 is provided with an upper pulley 6. Taking the first mill 3 as an example, its upper pulley 6 is connected to the lower pulley 8 by a belt 7 set downward. The lower pulley 8 of the first mill 3 is fixedly connected to the pulley shaft 2 by a coupling, and the pulley shaft 2 is connected to the output shaft of the power device 1 to achieve power transmission. Similarly, the upper pulley 6 of the second mill 4 and the third mill 5 is also connected to the lower pulley 8 by a belt 7 set downward, and the lower pulley 8 of the second mill 4 and the third mill 5 is also fixedly connected to the pulley shaft 2 by the axis, so as to achieve power transmission. It should be noted that the lower pulley 8 of the first mill 3, the second mill 4 and the third mill 5 is on the same horizontal line.

[0059] Specifically, taking the first mill 3 as an example, the power device 1 is started, and the output pump on the right side thereof rotates, driving the lower pulley 8, the belt 7, the upper pulley 6, and the mill input shaft 9 of the first mill 3 to rotate through the coupling. Since the mill input shaft 9 on the right side of the upper pulley 6 is fixedly connected to the spiral auger 10 provided in the housing of the first mill 3, the rotation of the mill input shaft 9 on the right side of the upper pulley 6 drives the spiral auger 10 to rotate, so that the horizontal transmission of the material can be realized, so that the material entering from the feed port 11 on the upper left side of the first mill 3 moves to the right side and then enters between the left grinding disc 12 and the right grinding disc 13. Since the left grinding disc 12 is fixedly connected to the housing of the first mill 3 and the right grinding disc 13 is fixedly connected to the outer periphery of the spiral auger 10, the left grinding disc 12 is stationary and the right grinding disc 13 rotates under the drive of the spiral auger 10, so that the relative rotation of the left grinding disc 12 and the right grinding disc 13 is realized, and the purpose of grinding plant tissue is finally achieved. The lower end of the first mill 3 is connected to the upper end of the second mill 4. After the first grinding is completed, the material is transferred from the first mill 3 to the second mill 4 via the intermediate interface 15 .

[0060] The grinding part is two relatively rotating annular discs, i.e., the left grinding disc 12 and the right grinding disc 13. The plant enters between the left grinding disc 12 and the right grinding disc 13. After grinding, the colloid and the non-colloid (the non-colloid becomes slag with a smaller particle size under the grinding action) are separated. There are many strip-shaped protrusions between the two grinding discs of the left grinding disc 12 and the right grinding disc 13. The strip-shaped protrusions are only one of the implementation methods of this embodiment and do not constitute a limitation of the present invention. They can also be set as arc-shaped protrusions or abrasive particles. There can be strip-shaped protrusions, arc-shaped protrusions or abrasive particles between the first grinding disc 3, the second grinding disc 4 and the third grinding disc 5, and the three can be the same or different. The left grinding disc 12 and the right grinding disc 13 are provided with an interlayer outside. Liquid nitrogen is introduced into the interlayer during grinding to reduce the temperature of the left grinding disc 12 and the right grinding disc 13.

[0061] Similarly, the second mill 4 can be driven by the power device 1 to realize the rotation of the lower pulley 8, belt 7, upper pulley 6, mill input shaft 9 of the second mill 4, and the rotation of the spiral auger 10 arranged in the housing of the second mill 4, so that the material entering from the middle interface 15 on the upper left side of the second mill 4 moves to the right side and then enters between the left grinding disc 12 and the right grinding disc 13. The relative rotation of the left grinding disc 12 and the right grinding disc 13 achieves the purpose of grinding plant tissue. The lower end of the second mill 4 is connected to the upper end of the third mill 5. After grinding, the material is transferred from the second mill 4 to the third mill 5 through the middle interface 15.

[0062] Similarly, the third mill 5 can be driven by the power device 1 to realize the rotation of the lower pulley 8, belt 7, upper pulley 6, mill input shaft 9 of the third mill 5, and the rotation of the spiral auger 10 arranged in the shell of the third mill 5, so that the material entering from the middle interface 15 on the upper left side of the third mill 5 moves to the right side and then enters between the left grinding disc 12 and the right grinding disc 13. The relative rotation of the left grinding disc 12 and the right grinding disc 13 achieves the purpose of grinding plant tissue. After grinding, the material is transferred from the third mill 5 to the separation tank. A vibrating screen is provided below the third mill 5 (below the first pre-treated material discharge port 14), and a separation tank is provided below the vibrating screen. The third mill 5 is connected to the separation tank below, so the first pre-treated material after grinding is transferred to the separation tank through the first pre-treated material discharge port 14 under the vibration of the vibrating screen.

[0063] The separation tank is surrounded by an annular vertical net, with an interlayer outside the annular vertical net and a stirring device inside. Under the stirring of the stirring device, the non-colloidal debris is transferred to the interlayer through the filter screen. The smaller the mesh number of the annular vertical net, the less the colloid loss; the larger the mesh number of the annular vertical net, the more the colloid loss. As the number of grinding increases, the particle size of the non-colloidal substance becomes smaller and smaller, but the particle size of the colloid does not change, which is more conducive to separation. A valve is provided on one side of the interlayer. The water and the non-colloidal debris in the interlayer of the separation tank can be discharged from the separation tank by opening the valve. A second pretreatment material discharge port and a valve are provided at the bottom of the separation tank. The plant rubber mixed with some non-colloidal debris can be transferred out by opening the valve for further grinding.

[0064] The extraction method of the present embodiment is as follows:

[0065] The first step: testing the water content of the raw material containing vegetable rubber, and the water content is 13%. Since the water content of the raw material is not high, the raw material is directly dry-ground in the mill.

[0066] Step 2: 1 kg of raw material is fed into the first mill 3 from the feed port 11 for grinding, and the grinding is performed three times in total. During grinding, the grinding environment temperature in the mill is controlled, and the set temperature is 10° C. During the grinding process, since a vibrating screen is installed under the mill, the first pre-treated product after grinding is transferred to a separation tank.

[0067] Step 3: sieve the first pre-treated material, and select the mesh size of the sieve as 400 meshes. After the sieve is sieved, obtain the second pre-treated material retained on the sieve.

[0068] Step 4: Using the second pre-treated product as a raw material for grinding, repeat the above steps 2 and 3 for three times to finally obtain 34.6 g of vegetable rubber, the rubber content of which was 82.6% as determined by the dissolution method.

[0069] Example 5

[0070] This embodiment adopts the grinding unit of embodiment 2, except that: in the grinding unit of this embodiment, no interlayer is provided outside the left grinding disc 12 and the right grinding disc 13, and the grinding unit does not need to be temperature controlled; and no vibrating screen is provided. The extraction method of this embodiment is as follows:

[0071] Step 1: Detect the moisture content of the raw material containing vegetable rubber, and the moisture content is 20%. Since the moisture content of the raw material is greater than 15%, wet grinding is used.

[0072] Step 2: 1 kg of raw material is fed into the first mill 3 from the feed port 11 for grinding, and the grinding is performed three times in total. Since the water content is relatively high and the water is fluid, the ground first pre-treated product can be automatically transferred to the separation tank under the action of gravity.

[0073] Step 3: Add water from the feed port 11, and the water flows to the separation tank. The amount of water is 15 kg, and the mass ratio of raw materials to water is 1:15. Add three times.

[0074] Step 4: Start the stirring device and sieve the first pre-treated product, the mesh number of the sieve is selected to be 400 meshes. The slag-water mixture is separated out of the separation tank, and the second pre-treated product retained on the sieve is obtained.

[0075] Step 5: Using the second pre-treated product as a raw material for grinding, repeat the above steps 3 and 4 for three times to finally obtain 37.1 g of vegetable rubber, the rubber content of which was 84.2% as determined by the dissolution method.

[0076] Example 6

[0077] This embodiment adopts the grinding unit of embodiment 2, except that: in the grinding unit of this embodiment, no interlayer is provided outside the left grinding disc 12 and the right grinding disc 13, and the grinding unit does not need to be temperature controlled; and no vibrating screen is provided. The extraction method of this embodiment is as follows:

[0078] Step 1: Detect the moisture content of the raw material containing vegetable rubber, and the moisture content is 20%. Since the moisture content of the raw material is greater than 15%, wet grinding is used.

[0079] Step 2: Mix 1 kg of raw material with water. The amount of water used is 15 kg, and the mass ratio of raw material to water is 1:15.

[0080] Step 3: Feed the mixture of raw materials and water into the first mill 3 from the feed port 11 for wet grinding, and grind three times in total. Since water has fluidity, the ground first pre-treated material can be automatically transferred to the separation tank under the action of gravity.

[0081] Step 4: Start the stirring device and sieve the first pre-treated product, the mesh number of the sieve is selected to be 400 meshes. The slag-water mixture is separated out of the separation tank, and the second pre-treated product retained on the sieve is obtained.

[0082] Step 5: Using the second pre-treated product as a raw material for grinding, repeat the above steps 3 and 4 for three times to finally obtain 35.1 g of vegetable rubber, the rubber content of which was 87.8% as determined by the dissolution method.

[0083] Comparative Example 1

[0084] The specific implementation process of this embodiment is substantially the same as that of embodiment 4, but the grinding unit adopted is not composed of three grinders connected in series, but five grinders connected in series, and finally connected to a separation tank. The extraction method of this embodiment is as follows:

[0085] The first step: testing the water content of the raw material containing vegetable rubber, and the water content is 13%. Since the water content of the raw material is not high, the raw material is directly dry-ground in the mill.

[0086] Step 2: 1 kg of raw material is fed into the first mill 3 from the feed port 11 for dry grinding, and a total of five grindings are performed. During grinding, the grinding environment temperature in the mill is controlled, and the set temperature is 10° C. During the grinding process, since a vibrating screen is installed under the mill, the first pre-treated product after grinding is transferred to a separation tank.

[0087] Step 3: sieve the first pre-treated material, and select the mesh size of the sieve as 400 meshes. After the sieve is sieved, obtain the second pre-treated material retained on the sieve.

[0088] Step 4: Use the second pretreated material as the raw material for grinding, repeat the above-mentioned steps 2 and 3, repeat three times, and finally obtain 26.6g of vegetable rubber. The rubber content was determined by the dissolution method to be 68.4%. It is presumed that after the raw material is ground multiple times, the heat generated by the grinding itself is prone to accumulate too much, thereby causing the melting of the gum, and the molten gum is prone to enveloping non-gum, which damages the purity of the gum. Even if cooling measures are configured, the problem of untimely heat conduction will easily cause excessive inclusions in some parts. Therefore, the number of grinding times in a single step should not exceed 4 times.

[0089] It should be pointed out that the above embodiments do not constitute a limitation of the present invention. For example, the number of grinding times can be adjusted according to the raw material conditions; for another example, the number of grinders in the grinding unit can also be adjusted, and each grinding unit can include two grinders or four grinders.

Claims

1. A method for extracting vegetable rubber, characterized in that The following steps are involved: S10: Detecting the water content of the raw material containing vegetable rubber; S20: grinding the raw material containing vegetable rubber for 1 to 4 times to obtain a first pretreated product; S30: screening the first pretreated product to obtain a second pretreated product; S40: using the second pretreated product as a raw material for grinding, repeating steps S20 and S30 for more than 3 times to obtain vegetable rubber.

2. The extraction method according to claim 1, wherein: In step S20, During grinding, the air pressure in the grinding equipment is greater than 101.325 kPa; Preferably, any one of nitrogen, carbon dioxide, helium, neon, argon, krypton, xenon and radon is introduced into the grinding device.

3. The extraction method according to claim 1, characterized in that: In step S30, The mesh size of the sieve during sieving is 40 to 1000 mesh, preferably 200 to 400 mesh.

4. The extraction method according to claim 1, characterized in that: The raw material containing plant rubber is any one of eucommia bark, dandelion, guayule and hevea brasiliensis.

5. The extraction method according to any one of claims 1 to 4, characterized in that: When the water content of the raw material containing vegetable rubber is less than 15%, the temperature in the grinding equipment is -50°C to 10°C, preferably -30°C to -10°C; Preferably, the grinding device is provided with an interlayer outside, and any one of liquid nitrogen, liquid carbon dioxide and ethanol is introduced into the interlayer.

6. The extraction method according to any one of claims 1 to 4, characterized in that: When the water content of the raw material containing vegetable rubber is ≥15%, in step S30, S301: The first pretreated material is transferred to a screen; S302: adding water to the first pretreated product; S303: Screening to obtain a second pretreated product.

7. The extraction method according to claim 6, characterized in that: The mass ratio of the first pretreated product to water is 1:(1-15), preferably 1:(3-10).

8. The extraction method according to any one of claims 1 to 4, characterized in that: When the water content of the raw material containing vegetable rubber is ≥15%, in step S20, S201: mixing the vegetable rubber with water; S202: Grind the mixture containing vegetable rubber and water for 2 to 4 times to obtain a first pretreated product.

9. The extraction method according to claim 8, characterized in that: The mass ratio of the first pretreated product to water is 1:(1-15), preferably 1:(3-10).

10. A vegetable rubber obtained by the extraction method according to any one of claims 1 to 9, characterized in that: The rubber content of the vegetable rubber is not less than 80%.

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