Method for extracting plant rubber and plant rubber

Abstract

The application discloses a method for extracting plant rubber, which comprises the following steps: grinding raw material containing plant rubber, grinding 1-20 times to obtain a first pretreated material; screening the first pretreated material to obtain a second pretreated material retained on a screen; and repeating the previous grinding and screening operations with the second pretreated material as the raw material for grinding, and repeating the operations for more than 3 times to finally obtain the plant rubber. The plant rubber can be extracted from plant tissues only by using the raw material, a grinder set and a separating screen. On the one hand, the use of organic solvents with certain toxicity is avoided, and the environment is not polluted; on the other hand, the extraction rate of the plant rubber is at least 80%, which is much higher than the extraction rate of the prior art.

Description

Technical Field

[0001] This invention relates to the field of plant rubber extraction technology, and more specifically, to a method for extracting plant rubber and plant rubber. Background Technology

[0002] With continuous innovation and revolution in industrial technology, the number of natural rubber products on the market is increasing, leading to a growing demand for natural rubber. Natural rubber, petroleum, steel, and coal are known as the world's four major industrial raw materials. As one of these four, natural rubber is favored across various industries due to its good elasticity and excellent mechanical properties at room temperature. Currently, my country imports over 80% of its natural rubber, making the search for a second source of natural rubber crucial for my country's rubber industry. Although over two thousand plant species can produce natural rubber, most have low rubber content.

[0003] Eucommia ulmoides is a plant unique to China, with over 95% of the world's Eucommia ulmoides resources located in China. It is also the world's most widely adaptable and highest-potential high-quality gum-producing tree species. The leaves, bark, and fruit peel of Eucommia ulmoides are rich in a white, filamentous substance, known as Eucommia gum. Eucommia gum is an excellent polymer material with both rubber and plastic properties, and its main component is trans-polyisoprene. Currently, its extraction technologies mainly include organic solvent extraction and fermentation extraction, but the extraction rate is only about 30%, making it unsuitable for industrial applications. Furthermore, the organic solvents used in organic solvent extraction have a certain degree of toxicity, causing serious environmental pollution, and are relatively expensive.

[0004] Therefore, developing a method to improve the extraction rate of plant 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 this invention is to propose a method for extracting plant rubber, which can extract plant rubber from plant tissue using only raw materials, a mill and a separation tank, and the extraction rate of plant rubber is at least 80%.

[0006] To address the aforementioned technical problems, this invention provides a method for extracting plant rubber, comprising the following steps:

[0007] S10: Detect the moisture content of raw materials containing plant rubber;

[0008] S20: Grind the raw material containing plant rubber 1 to 4 times to obtain the first pretreated material;

[0009] S30: The first pretreated material is sieved to obtain the second pretreated material;

[0010] S40: Using the second pretreated material as the raw material for grinding, repeat steps S20 and S30 for at least 3 times to obtain plant rubber.

[0011] The extraction method of this invention achieves superior extraction results due to the use of grinding. During the intense extrusion and kneading process of grinding, the non-colloidal substances in the raw material are continuously ground down, resulting in increasingly smaller particle sizes. Meanwhile, the colloidal substances in the raw material, due to their inherent viscosity and elasticity, retain their particle size even after repeated grinding, making them more likely to remain on the sieve during sieving. The smaller-sized non-colloidal particles, however, pass through the sieve and are sieved out. Furthermore, the sieving operation is interspersed between several grinding processes. This serves two purposes: firstly, it allows for rapid removal of impurities, reducing ineffective grinding of large quantities of impurities; secondly, it prevents the heat generated by prolonged grinding from causing the colloidal substances to melt. Molten colloidal substances can easily trap non-colloidal substances within the colloidal mixture, making it difficult to improve the final purity of the colloidal substance.

[0012] In a preferred embodiment of the present invention, in step S20, during grinding, the air pressure inside the grinding equipment is greater than 101.325 kPa to prevent moisture from entering the equipment. If external moisture enters the grinding equipment, it will freeze. On the one hand, ice crystals increase the ineffective power consumption of grinding, and may even freeze the grinding disc, causing equipment malfunction. On the other hand, frozen moisture will continuously accumulate within the raw material, and during sieving, as the ice crystals melt, the material becomes viscous, hindering the smooth sieving process. Therefore, it is necessary to maintain an air pressure greater than 101.325 kPa inside the grinding equipment. 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 supplies a protective gas to maintain positive pressure during the grinding process, thereby isolating the raw material from external air to prevent contact between the raw material and external moisture. These gases will not affect the grinding of raw materials containing plant rubber, and can ensure that the air pressure inside the grinding equipment is greater than 101.325 kPa, achieving the purpose of preventing moisture from entering the equipment.

[0013] In a preferred embodiment of the present invention, the raw material containing plant rubber is any one of Eucommia ulmoides, dandelion, sage, and rubber tree. 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. Those skilled in the art can select an appropriate mesh size based on actual conditions (such as different raw materials containing plant rubber).

[0014] In a preferred embodiment of the present invention, when the moisture content of the raw material containing plant rubber is <15%, the temperature inside the grinding equipment is -50℃ to 10℃, preferably -30℃ to -10℃. As the number of grinding cycles increases, the temperature inside the grinding equipment gradually rises. By controlling the temperature inside the grinding equipment to be below the glass transition temperature of the plant rubber, excessive non-rubber substances are avoided from being entrained as the rubber gradually transforms into a glassy state. This facilitates the subsequent separation of the second pre-treated material and improves the final purity. In a more preferred embodiment of the present invention, the grinding equipment is provided with an outer jacket. Liquid nitrogen, liquid carbon dioxide, or ethanol is introduced into the jacket to maintain the temperature inside the grinding equipment at -50℃ to 10℃, preferably -30℃ to -10℃. Specifically, a cryogenic cooling liquid circulation pump can be used to circulate the liquid within the jacket, thereby maintaining the temperature inside the grinding equipment within the preset range.

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

[0016] S301: The first pre-treated material is transferred to a sieve;

[0017] S302: Add water to the first pretreated material;

[0018] S303: Sieve to obtain the second pretreated material.

[0019] It should be noted that in step S302, adding water helps to transfer some of the first pretreatment material adhering to the grinding equipment after grinding to the screen, further improving the extraction rate of plant rubber. Preferably, the mass ratio of the first pretreatment material to water is 1:(1-15), more preferably 1:(3-10). Water can be added to the first pretreatment material all at once or in several portions.

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

[0021] S201: Mix the plant-based rubber with water;

[0022] S202: Grind the mixture containing plant rubber and water 1 to 4 times to obtain the first pretreated material.

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

[0024] This invention involves feeding raw materials and water together into a grinding device in a specific ratio. During the grinding process, the water generates shear force due to its flow and scouring, resulting in a high degree of separation between the colloidal and non-colloidal substances. A raw material mixture with a ratio of 1:(1-15) not only achieves a relatively good hydraulic scouring and shearing effect but also facilitates improved material flowability and sieving efficiency during screening. However, further increasing the amount of water added results in a lower effective material content per unit volume, which is detrimental to colloidal extraction and increases the proportion of wasted energy in the grinding device, hindering energy conservation and environmental protection.

[0025] The second objective of this invention is to provide a plant rubber obtained by an extraction method according to one objective of this invention, wherein the plant rubber has a rubber content of not less than 80%.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] 1. The extraction method of the present invention uses only raw materials, grinding equipment, and separation equipment, or a small amount of water, to extract plant rubber from plant tissue. On the one hand, it avoids the use of organic solvents with certain toxicity, thus preventing environmental pollution; on the other hand, the extraction rate of plant rubber is at least 80%, which is far higher than the extraction rate of existing technologies.

[0028] 2. The plant rubber obtained by the extraction method of this invention is suitable for industrial applications. Firstly, it can be used to manufacture medical devices that operate under relatively mild conditions, such as dental materials and prostheses. Secondly, it can be used as a raw material for further separation and purification until the purity reaches 95%. In addition, the sludge-water mixture discharged by this invention can be used to produce industrial fertilizers, realizing the comprehensive utilization of all parts of the plant. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the mill used in the present invention for extracting plant rubber;

[0030] Figure 2 A schematic diagram of the structure of the grinding unit for extracting plant rubber according to the present invention.

[0031] Among them, 1-power unit, 2-pulley shaft, 3-first mill, 4-second mill, 5-third mill, 6-upper pulley, 7-belt, 8-lower pulley, 9-mill input shaft, 10-spiral auger, 11-feed inlet, 12-left grinding disc, 13-right grinding disc, 14-first pre-treated material outlet, 15-intermediate interface. Detailed Implementation

[0032] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0033] In this invention, the raw material containing plant rubber used is Eucommia bark, which has a rubber content of approximately 6% to 10%. However, it should be noted that this method is also applicable to the extraction of plant rubber from other sources, such as dandelion, silver hyacinth, or rubber trees.

[0034] In this invention, the moisture content is a mass fraction, that is, the percentage of water content to the total weight of the raw material. A portion of the sample is taken and weighed, m1; then dried and weighed again, m2; moisture 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 auger 10 located inside the mill housing. Therefore, after power input, the mill input shaft 9 will rotate, driving the auger 10 to rotate. This enables the horizontal conveying of materials, allowing materials entering from the feed inlet 11 on the upper side of the mill to move to the right side and then into the grinding disc. The grinding disc includes two annular discs, namely... Figure 1 The mill consists of a left grinding disc 12 and a right grinding disc 13. Numerous strip-shaped protrusions are provided between the left and right grinding discs 12 and 13. These strip-shaped protrusions are only one implementation method in this embodiment and do not constitute a limitation of the invention. They can also be arc-shaped protrusions or abrasive grains. Here, the abrasive grains refer to grinding wheels with numerous abrasive grains on the surface of both the left and right grinding discs 12 and 13. Since the left grinding disc 12 is fixedly connected to the mill housing and the right grinding disc 13 is fixedly connected to the outer periphery of the auger 10, the left grinding disc 12 remains stationary while the right grinding disc 13 rotates under the drive of the auger 10, achieving relative rotation between the left and right grinding discs 12 and 13, ultimately achieving the purpose of grinding plant tissue. A jacket is provided outside the left and right grinding discs 12 and 13, and liquid nitrogen is introduced into the jacket to reduce the temperature of the left and right grinding discs 12 and 13. A first pre-treated material outlet 14 is provided below the mill.

[0037] It should be noted that a power unit is located on the left side of the mill, and a vibrating screen is located below the mill (below the first pre-treated material outlet 14). A separation tank is located below the vibrating screen, and the mill is connected to the separation tank. Therefore, after grinding, the first pre-treated material is transferred to the separation tank through the first pre-treated material outlet 14 under the vibration of the vibrating screen. Figure 1The power unit and vibrating screen are not shown; existing power units and vibrating screens can be used. A ring-shaped vertical mesh is installed around the perimeter of the separation tank, vertically downwards and encircling the tank. An outer layer surrounds the ring-shaped mesh, and an inner layer houses a stirring device. Under the stirring of the stirring device and the vibration of the vibrating screen, the fragmented non-rubber material is transferred through the mesh to the outer layer of the separation tank. The smaller the mesh size of the ring-shaped mesh, the less rubber loss; the larger the mesh size, the greater the rubber loss. A valve is located on one side of the outer layer of the separation tank; opening the valve allows the fragmented non-rubber material to be discharged. A second pre-treated material outlet and valve are located at the bottom of the separation tank; opening the valve allows the plant rubber mixed with some fragmented non-rubber material to be transferred to the next mill.

[0038] The extraction method in this embodiment is as follows:

[0039] Step 1: The moisture content of the raw material containing plant rubber was tested and found to be 14%. Because the moisture content of the raw material is not high, it was directly dry-ground in the mill.

[0040] Step 2: Feed 1 kg of raw material into the mill through inlet 11 and grind it once to obtain the first pre-treated material. The grinding environment temperature inside the mill is controlled during grinding, and the set temperature is -50℃. During the grinding process, since a vibrating screen is installed below the mill, the first pre-treated material is transferred to a separation tank after grinding.

[0041] Step 3: Sieve the first pretreated material through a 40-mesh sieve. Because the non-colloidal particles become smaller during grinding, they are transferred through the filter screen into the jacket of the separator under stirring and vibration. Open the valve at the bottom of the separator, and the second pretreated material, totaling 266.3g, is transferred out through the second pretreated material outlet at the bottom of the separator.

[0042] Step 4: Using the second pretreated material as the grinding raw material, repeat steps 2 and 3 above, nine times, to finally obtain 22.1g of plant rubber. The rubber content was determined to be 80.3% using the dissolution method.

[0043] Example 2

[0044] This embodiment uses the mill from Embodiment 1, with the difference that: in this embodiment, the left grinding disc 12 and right grinding disc 13 do not have an outer layer, so temperature control of the grinding unit is not required; and no vibrating screen is provided. The extraction method in this embodiment is as follows:

[0045] Step 1: The moisture content of the raw material containing plant rubber was tested and found to be 18%. Since the moisture content of the raw material is greater than 15%, the wet milling method was adopted.

[0046] Step 2: Feed 1 kg of raw material into the mill through inlet 11 and grind it once at room temperature to obtain the first pretreated material. Due to the relatively high water content and the fluidity of water, the first pretreated material after grinding can be automatically transferred to the separation tank under gravity.

[0047] Step 3: Add water through inlet 11, allowing it to flow into the separator. The amount of water used is 10 kg, with a raw material to water mass ratio of 1:10. Add the water in three portions.

[0048] Step 4: Start the stirring device and sieve the first pretreated material through a 200-mesh screen. Under the action of stirring, the mixture of granular non-gelatinous material and water is separated out of the separation tank, and the second pretreated material (281.7g) remaining on the screen is transferred out.

[0049] Step 5: Using the second pretreated material as the grinding material, repeat steps 3 and 4 above, nine times, to finally obtain 35.9g of plant rubber. The rubber content was determined to be 83.8% using the dissolution method.

[0050] Example 3

[0051] This embodiment uses the mill from Embodiment 1, with the difference that: in this embodiment, the left grinding disc 12 and right grinding disc 13 do not have an outer layer, so temperature control of the grinding unit is not required; and no vibrating screen is provided. The extraction method in this embodiment is as follows:

[0052] Step 1: The moisture content of the raw material containing plant rubber was tested and found to be 18%. Since the moisture content of the raw material is greater than 15%, the wet milling method was adopted.

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

[0054] Step 3: The mixture of raw materials and water is fed into the mill through inlet 11 and ground once at room temperature to obtain the first pretreated product. Due to the fluidity of water, the ground first pretreated product can be automatically transferred to the separation tank under gravity.

[0055] Step 4: Start the stirring device and sieve the first pretreated material through a 200-mesh screen. Under the action of stirring, the mixture of granular non-gelatinous material and water is separated out of the separation tank, and the second pretreated material (274.5g) remaining on the screen is transferred out.

[0056] Step 5: Using the second pretreated material as the grinding material, repeat steps 3 and 4 above, nine times, to finally obtain 34.7g of plant rubber. The rubber content was determined to be 84.8% using the dissolution method.

[0057] Example 4

[0058] The grinding unit in this embodiment is as follows: Figure 2 As shown, by Figure 2 It can be seen that the leftmost part is the fixed power unit 1, and the right side of it is equipped with an output shaft. Figure 2 From top to bottom on the right side are the first mill 3, the second mill 4, and the third mill 5, which constitute a grinding unit. 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 in Embodiment 1. Each of the first mill 3, the second mill 4, and the third mill 5 has an upper pulley 6 on its left side. Taking the first mill 3 as an example, its upper pulley 6 is connected to a lower pulley 8 via a downwardly arranged belt 7. The lower pulley 8 of the first mill 3 is fixedly connected to a pulley shaft 2, which is connected to the output shaft of the power unit 1 via a coupling to achieve power transmission. Similarly, the upper pulleys 6 of the second mill 4 and the third mill 5 are also connected to the lower pulleys 8 via downwardly arranged belts 7, and the lower pulleys 8 of the second mill 4 and the third mill 5 are also fixedly connected to the pulley shaft 2 at their centers to achieve power transmission. It should be noted that the lower pulleys 8 of the first mill 3, the second mill 4, and the third mill 5 are on the same horizontal line.

[0059] Specifically, taking the first mill 3 as an example, when the power unit 1 is started, its right-side output pump rotates, driving the lower pulley 8, belt 7, upper pulley 6, and mill input shaft 9 of the first mill 3 to rotate via a coupling. Since the mill input shaft 9 on the right side of the upper pulley 6 is fixedly connected to the auger 10 located inside 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 auger 10 to rotate, thus achieving horizontal material conveying. This allows the material entering from the feed inlet 11 on the upper left side of the first mill 3 to move to the right side and then into the space 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 auger 10, the left grinding disc 12 remains stationary while the right grinding disc 13 rotates under the drive of the auger 10, achieving relative rotation between the left and right grinding discs 12 and ultimately achieving the purpose of grinding plant tissue. 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 through the intermediate interface 15.

[0060] The grinding process is achieved between two relatively rotating annular discs, namely the left grinding disc 12 and the right grinding disc 13. The plant material enters between the left and right grinding discs 12 and 13, and after grinding, the gum and non-gum (the non-gum becomes smaller particles under grinding) are separated. There are numerous strip-shaped protrusions between the left and right grinding discs 12 and 13. These strip-shaped protrusions are only one implementation method in this embodiment and do not constitute a limitation of the invention; they can also be arc-shaped protrusions or abrasive grains. The protrusions between the first mill 3, the second mill 4, and the third mill 5 can be strip-shaped, arc-shaped, or abrasive grains; they can be the same or different. A sandwich layer is provided outside the left and right grinding discs 12 and 13. During grinding, liquid nitrogen is introduced into the sandwich layer to reduce the temperature of the left and right grinding discs 12 and 13.

[0061] Similarly, driven by the power unit 1, the second mill 4 rotates its lower pulley 8, belt 7, upper pulley 6, and mill input shaft 9, and the auger 10 located inside the casing of the second mill 4. This causes the material entering from the middle interface 15 on the upper left side of the second mill 4 to move to the right side and then into the space 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, driven by the power unit 1, the third mill 5 rotates its lower pulley 8, belt 7, upper pulley 6, and mill input shaft 9, and the auger 10 located inside the casing of the third mill 5. This causes the material entering from the middle interface 15 on the upper left side of the third mill 5 to move to the right side and then into the space 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 located below the third mill 5 (below the discharge port 14 of the first pretreatment material), and a separation tank is located below the vibrating screen. The third mill 5 is connected to the separation tank, so the first pretreatment material after grinding is transferred to the separation tank through the discharge port 14 of the first pretreatment material under the vibration of the vibrating screen.

[0063] The separator is surrounded by annular vertical mesh, with an outer layer and an inner stirring device. Under the stirring of the device, fragmented non-rubber materials are transferred through the mesh into the inner layer. The smaller the mesh size of the annular vertical mesh, the less rubber loss; the larger the mesh size, the greater the rubber loss. With increasing grinding cycles, the particle size of the non-rubber materials decreases, while the particle size of the rubber materials remains unchanged, facilitating separation. A valve is located on one side of the inner layer; opening the valve allows water and fragmented non-rubber materials to be discharged from the separator. A second pretreatment outlet and valve are located at the bottom of the separator; opening the valve allows the plant rubber mixed with some fragmented non-rubber materials to be transferred out for further grinding.

[0064] The extraction method in this embodiment is as follows:

[0065] Step 1: The moisture content of the raw material containing plant rubber was tested and found to be 13%. Since the moisture content of the raw material is not high, it will be dry-ground directly in the mill.

[0066] Step 2: 1 kg of raw material is fed into the first mill 3 through feed inlet 11 for grinding, which is carried out three times. The grinding environment temperature inside the mill is controlled during grinding, and the set temperature is 10℃. During the grinding process, since a vibrating screen is installed below the mill, the first pre-treated material is transferred to a separation tank after grinding.

[0067] Step 3: Sieve the first pretreated material through a sieve with a mesh size of 400. After completion, obtain the second pretreated material remaining on the sieve.

[0068] Step 4: Using the second pretreated material as the grinding raw material, repeat steps 2 and 3 above, repeating three times, to finally obtain 34.6g of plant rubber. Its rubber content was determined to be 82.6% using the dissolution method.

[0069] Example 5

[0070] This embodiment uses the grinding unit of Embodiment 2, the difference being that: in this embodiment, the left grinding disc 12 and right grinding disc 13 do not have an outer layer, so temperature control of the grinding unit is not required; and no vibrating screen is provided. The extraction method of this embodiment is as follows:

[0071] Step 1: The moisture content of the raw material containing plant rubber was tested and found to be 20%. Since the moisture content of the raw material is greater than 15%, the wet milling method was adopted.

[0072] Step 2: 1 kg of raw material is fed into the first mill 3 through the feed inlet 11 for grinding, and the grinding process is repeated three times. Due to the relatively high water content and the fluidity of water, the first pre-treated material after grinding can be automatically transferred to the separation tank under gravity.

[0073] Step 3: Add water through inlet 11, allowing it to flow into the separator. The amount of water used is 15 kg, with a raw material to water mass ratio of 1:15. Add the water in three portions.

[0074] Step 4: Start the stirring device and sieve the first pretreated material through a 400-mesh screen. The sludge-water mixture is separated from the separation tank, and the second pretreated material remaining on the screen is obtained.

[0075] Step 5: Using the second pretreated material as the grinding raw material, repeat steps 3 and 4 three times to finally obtain 37.1g of plant rubber. The rubber content was determined to be 84.2% using the dissolution method.

[0076] Example 6

[0077] This embodiment uses the grinding unit of Embodiment 2, the difference being that: in this embodiment, the left grinding disc 12 and right grinding disc 13 do not have an outer layer, so temperature control of the grinding unit is not required; and no vibrating screen is provided. The extraction method of this embodiment is as follows:

[0078] Step 1: The moisture content of the raw material containing plant rubber was tested and found to be 20%. Since the moisture content of the raw material is greater than 15%, the wet milling method was adopted.

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

[0080] Step 3: The mixture of raw materials and water is fed into the first mill 3 through the feed inlet 11 for wet grinding, which is carried out three times. Due to the fluidity of water, the first pre-treated material after grinding can be automatically transferred to the separation tank under the action of gravity.

[0081] Step 4: Start the stirring device and sieve the first pretreated material through a 400-mesh screen. The sludge-water mixture is separated from the separation tank, and the second pretreated material remaining on the screen is obtained.

[0082] Step 5: Using the second pretreated material as the grinding raw material, repeat steps 3 and 4 three times to finally obtain 35.1g of plant rubber. The rubber content was determined to be 87.8% using the dissolution method.

[0083] Comparative Example 1

[0084] The specific implementation process of this embodiment is largely the same as that of Embodiment 4, but the grinding unit used is not a three-grinding unit connected in series, but a five-grinding unit connected in series, which is finally connected to the separation tank. The extraction method of this embodiment is as follows:

[0085] Step 1: The moisture content of the raw material containing plant rubber was tested and found to be 13%. Since the moisture content of the raw material is not high, it will be dry-ground directly in the mill.

[0086] Step 2: 1 kg of raw material is fed into the first mill 3 through feed inlet 11 for dry grinding, which is carried out five times. The grinding environment temperature inside the mill is controlled during grinding, and the set temperature is 10℃. During the grinding process, since a vibrating screen is installed below the mill, the first pre-treated material is transferred to a separation tank after grinding.

[0087] Step 3: Sieve the first pretreated material through a sieve with a mesh size of 400. After completion, obtain the second pretreated material remaining on the sieve.

[0088] Step 4: Using the second pretreated material as the grinding material, repeat steps 2 and 3 three times to obtain 26.6g of plant rubber. The rubber content was determined to be 68.4% using the dissolution method. It is presumed that after repeated grinding, the heat generated by the grinding process tends to accumulate excessively, causing the rubber to melt. The molten rubber easily encapsulates non-rubber materials, damaging the purity of the rubber. Even with cooling measures, the problem of delayed heat conduction can easily lead to excessive localized inclusions. Therefore, the number of grinding cycles in a single step should not exceed four.

[0089] It should be noted 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; and for example, the number of mills in the grinding unit can also be adjusted, and each grinding unit may include two mills or four mills.

Claims

1. A method for extracting plant rubber, characterized in that... Includes the following steps: S10: Detect the moisture content of the raw material containing plant rubber; the raw material containing plant rubber is Eucommia ulmoides; S20: Grind the raw material containing plant rubber 1 to 4 times to obtain the first pretreated material; S30: The first pretreated material is sieved to obtain the second pretreated material; S40: Using the second pretreated material as the raw material for grinding, repeat steps S20 and S30 for more than 3 times to obtain plant rubber; When the moisture content of the raw material containing plant rubber is <15%, the temperature inside the grinding equipment is -50℃ to 10℃; When the moisture content of the raw material containing plant rubber is ≥15%, in step S30, S301: the first pretreated material is transferred to a sieve; S302: water is added to the first pretreated material; S303: the material is sieved to obtain the second pretreated material; or, when the moisture content of the raw material containing plant rubber is ≥15%, in step S20, S201: the plant rubber is mixed with water; S202: the mixture of plant rubber and water is ground 2-4 times to obtain the first pretreated material; wherein the mass ratio of the first pretreated material to water is 1:(3-10); The grinding process is achieved by two relatively rotating annular discs, a left grinding disc and a right grinding disc; there are multiple strip-shaped protrusions between the two grinding discs.

2. The extraction method as described in claim 1, characterized in that: In step S20, During grinding, the air pressure inside the grinding equipment is greater than 101.325 kPa.

3. The extraction method as described in claim 2, characterized in that: In step S20, The grinding equipment is introduced with any one of nitrogen, carbon dioxide, helium, neon, argon, krypton, xenon and radon.

4. The extraction method as described in claim 1, characterized in that: In step S30, The mesh size of the sieve during sieving is 40 to 1000 mesh.

5. The extraction method as described in claim 4, characterized in that: In step S30, The mesh size of the sieve during sieving is 200 to 400 mesh.

6. The extraction method as described in claim 1, characterized in that: When the moisture content of the raw material containing plant rubber is <15%, the temperature inside the grinding equipment is -30℃ to -10℃.

7. The extraction method as described in claim 6, characterized in that: The grinding equipment is provided with an outer jacket, into which any one of liquid nitrogen, liquid carbon dioxide, or ethanol is introduced.

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