Natural rubber solidification system, natural rubber as well as preparation method and application of natural rubber

Abstract

The invention belongs to the technical field of natural rubber processing and application, and particularly relates to a natural rubber solidification system, natural rubber and a preparation method and application thereof. The natural rubber solidification system provided by the invention comprises choline compounds and organic acid, the mass ratio of the choline compound to the organic acid is (0.1-0.2): (0.1-0.2). The natural rubber solidification system provided by the invention is applied to preparation of natural rubber, and the molecular structure of rubber hydrocarbon can be prevented from being damaged, so that the strength of the natural rubber (also known as raw rubber) can be greatly improved, the deflection resistance and aging resistance of the natural rubber are improved, and the shelf life of the natural rubber and the service life of a tire are prolonged.

Description

Technical Field

[0001] The invention belongs to the technical field of natural rubber processing and application, and specifically relates to a natural rubber coagulation system, natural rubber and a preparation method and application thereof. Background Art

[0002] The sidewall rubber is located on the outer cord layer of the tire, and its main function is to protect the tire body from mechanical damage, atmospheric effects and humid environment. Since the sidewall rubber is often under periodic flexion and deformation, and is eroded by oxygen, ozone and ultraviolet rays in the atmosphere, it needs to have excellent flexion resistance and aging resistance. These properties ensure that the tire can maintain good elasticity and durability during long-term use, thereby ensuring driving safety. However, special vehicle tires used in tropical areas have short driving time and long parking time. They are exposed to the outdoors under compression conditions all year round, and are eroded by sunlight, thermal oxygen and ozone, resulting in aging and cracking.

[0003] In order to solve the above-mentioned problem that the tire sidewall is not resistant to aging during long-term use in tropical areas, either excellent antioxidants with different ratios are used to extend the aging period, or protective coatings are applied to the sidewalls to protect the sidewalls from erosion by media such as heat oxygen, sunlight, and ozone. However, these methods cannot fundamentally solve the aging problem due to the lack of resistance to extraction or coating shedding. Summary of the invention

[0004] The purpose of the present invention is to provide a natural rubber coagulation system, a natural rubber and a preparation method and application thereof. The natural rubber prepared by the natural rubber coagulation system provided by the present invention has the advantages of high strength, flex resistance and aging resistance, can meet the use requirements of high-end tire sidewall rubber, and the preparation process is green and environmentally friendly, and is suitable for industrial application.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] The invention provides a natural rubber coagulation system, comprising a choline compound and an organic acid; the mass ratio of the choline compound to the organic acid is (0.1-0.2): (0.1-0.2).

[0007] Preferably, the choline compound includes choline bitartrate and / or choline dihydrogen citrate.

[0008] Preferably, the organic acid comprises citric acid and / or malic acid.

[0009] The present invention provides a method for preparing natural rubber, comprising the following steps:

[0010] Mixing natural latex and water to obtain diluted latex;

[0011] Mixing the natural rubber coagulation system described in the above technical solution with water to obtain a coagulant solution;

[0012] The diluted latex and the coagulant solution are mixed and aged to obtain the natural rubber.

[0013] Preferably, the natural latex is gel-free; the ammonia content in the natural latex is less than 0.05wt%;

[0014] The dry rubber content of the diluted latex is 23-25wt%.

[0015] Preferably, the mass percentage of the choline compound in the natural rubber coagulation system to the mass percentage of the dry rubber in the natural latex is 0.1-0.2%;

[0016] The mass percentage of the organic acid in the natural rubber coagulation system to the mass percentage of the dry rubber in the natural latex is 0.1-0.2%.

[0017] Preferably, the aging time is 8 to 12 hours.

[0018] The present invention provides natural rubber prepared by the preparation method described in the above technical scheme.

[0019] The present invention provides the use of the natural rubber described in the above technical solution in preparing tire sidewall rubber.

[0020] The present invention provides a tire sidewall rubber, comprising the following components in parts by mass:

[0021] The above technical scheme comprises 50-70 parts of natural rubber, 20-40 parts of EPDM, 5-15 parts of butadiene rubber, 30-50 parts of carbon black, 5-7 parts of aromatic oil, 4-6 parts of zinc oxide, 0.5-1.5 parts of stearic acid, 1-3 parts of protective wax, 3-5 parts of antioxidant, 0.5-1.5 parts of 203 resin, 1-2 parts of sulfur, 1-1.5 parts of accelerator, 0.1-1 parts of anti-reversion agent and 0.1-0.3 parts of scorch retarder.

[0022] The present invention provides a natural rubber coagulation system, comprising a choline compound and an organic acid; the mass ratio of the choline compound to the organic acid is (0.1-0.2): (0.1-0.2). The H of the organic acid in the coagulation system provided by the present invention is +It can not only reduce the pH value of natural latex, but also be used by bacteria to promote the formation of volatile fatty acids, thereby accelerating the coagulation of natural latex; the choline compounds in the coagulation system provided by the present invention have good solubility in natural latex, and can react with phospholipids in natural latex under normal temperature and pressure conditions, and destroy the stability of rubber particles without destroying the molecular structure of rubber hydrocarbons, so that latex coagulates, and improves the coagulation efficiency of natural latex. At the same time, since the molecular structure of rubber hydrocarbons is not destroyed, the strength of the obtained natural rubber is greatly improved; at the same time, the choline compounds in the coagulation system remain in the natural rubber, and can also accelerate the vulcanization of rubber, and play an anti-aging role for natural rubber. The natural rubber coagulation system provided by the present invention is applied to the preparation of natural rubber, and can keep the molecular structure of rubber hydrocarbons from being destroyed, thereby greatly improving the strength of natural rubber (also known as raw rubber), and at the same time improving the flexural resistance and aging resistance of natural rubber, extending the shelf life of natural rubber and the service life of tires.

[0023] The present invention provides a method for preparing natural rubber, comprising the following steps: mixing natural latex and water to obtain diluted latex; mixing the natural rubber coagulation system described in the above technical solution with water to obtain a coagulant solution; mixing the diluted latex and the coagulant solution for maturation to obtain the natural rubber. The present invention uses the natural rubber coagulation system described in the above technical solution to coagulate natural latex through natural chemical reactions, with high coagulation efficiency and green environmental protection. More importantly, the molecular structure of rubber hydrocarbons is not destroyed, and the obtained natural rubber has the advantages of high strength, flex resistance, and aging resistance. At the same time, the raw materials of the coagulation system used in the present invention are safe and non-toxic, no corrosive acid is added, the preparation process is non-toxic and safe, and there is no damage to equipment and production personnel. It is a green and environmentally friendly preparation method suitable for industrial application. DETAILED DESCRIPTION

[0024] The invention provides a natural rubber coagulation system, comprising a choline compound and an organic acid; the mass ratio of the choline compound to the organic acid is (0.1-0.2): (0.1-0.2).

[0025] In the present invention, unless otherwise specified, all preparation raw materials / components are commercially available products well known to those skilled in the art.

[0026] The natural rubber coagulation system provided by the present invention comprises a choline compound. In the present invention, the choline compound preferably comprises choline bitartrate and / or choline dihydrogen citrate.

[0027] The natural rubber coagulation system provided by the present invention comprises an organic acid. In the present invention, the organic acid preferably comprises citric acid and / or malic acid.

[0028] In the present invention, the mass ratio of the choline compound to the organic acid is (0.1-0.2):(0.1-0.2), preferably 1:1.

[0029] The present invention provides the application of the natural rubber coagulation system described in the above technical solution in the preparation of natural rubber. The present invention has found that the physical properties of natural rubber obtained by coagulating the traditional natural rubber coagulant (i.e., formic acid) are poor and fail to meet the requirements of high-end rubber indicators (including tensile strength, elongation at break, tear strength, and compression fatigue temperature rise); and formic acid is highly corrosive and has a pungent taste, which not only corrodes equipment but is also detrimental to physical and mental health. Therefore, the natural rubber coagulation system provided by the present invention uses natural organic acids (preferably citric acid and / or malic acid) to replace formic acid (the acidity of citric acid and malic acid is equivalent to that of formic acid), which is green and environmentally friendly. The organic acid H in the natural rubber coagulation system provided by the present invention is + It can not only reduce the pH value of natural latex, but also be used by bacteria to promote the formation of volatile fatty acids and accelerate the coagulation of natural latex. At the same time, choline compounds and organic acids are also used in the natural rubber coagulation system. Choline compounds have good solubility in natural latex, and can react with phospholipids in natural latex at normal temperature and pressure to destroy the stability of rubber particles in natural latex, so that natural latex is coagulated, and the coagulation efficiency of Tiane'an latex is improved. Therefore, the natural rubber coagulation system provided by the present invention uses natural chemical reactions to coagulate natural latex, which is non-toxic and safe, does not add corrosive acids, has high coagulation efficiency and is green and environmentally friendly; more importantly, it does not destroy the molecular structure of rubber hydrocarbons, greatly improving the strength and anti-aging effect of the natural effect.

[0030] The present invention provides a method for preparing natural rubber, comprising the following steps:

[0031] Mixing natural latex and water to obtain diluted latex;

[0032] Mixing the natural rubber coagulation system described in the above technical solution with water to obtain a coagulant solution;

[0033] The diluted latex and the coagulant solution are mixed and aged to obtain the natural rubber.

[0034] The present invention mixes natural latex and water to obtain diluted latex. In the present invention, the natural latex is preferably fresh natural latex. The natural latex preferably contains fats, sterols, phospholipids, etc., all of which are insoluble in water and adsorbed on the surface of rubber particles. The mass of lipids in the natural latex preferably accounts for about 1% of the mass of the natural latex, of which 0.6% is phospholipids. Phospholipids are long-chain fatty acid esters of glycerophosphate with high surface activity. The phosphate groups of the phospholipids in the natural latex can undergo esterification reaction with the choline compounds in the natural rubber coagulation system. The choline compounds in the above-mentioned natural rubber coagulation system provided by the present invention react with the phospholipids in the natural latex to destroy the stability of the rubber particles in the natural latex and coagulate the natural latex; on the other hand, the choline compounds are present in the natural rubber obtained after coagulation, which can not only accelerate the vulcanization of the natural rubber but also have an anti-aging effect on the natural rubber.

[0035] In the present invention, the natural latex is gel-free; the ammonia content in the natural latex is preferably less than 0.05wt%. The dry rubber content of the natural latex is preferably 30wt%. The dry rubber content of the diluted latex is preferably 23-25wt%. In the present invention, the mixing of the natural latex and water is preferably carried out in a mixing tank.

[0036] The present invention mixes the natural rubber coagulation system described in the above technical solution with water to obtain a coagulant solution. In the present invention, the mixing of the natural rubber coagulation system and water is preferably carried out in an acid pool. In the present invention, the mass of the choline compound in the natural rubber coagulation system preferably accounts for 0.1-0.2% of the mass of the dry rubber in the natural latex, and can be 0.1% in the embodiment. The mass of the organic acid in the natural rubber coagulation system preferably accounts for 0.1-0.2% of the mass of the dry rubber in the natural latex, and can be 0.1% in the embodiment. The present invention has no special requirements for the amount of water used when the natural rubber coagulation system and water are mixed. The mass of the choline compound and the organic acid in the natural rubber coagulation system provided by the present invention accounts for the mass of the dry rubber in the natural latex. The mass ratio cannot be too large or too small. When the amount is too large, it is easy to cause the natural latex to coagulate too fast, and the hardness of the obtained clot is too high, which is not conducive to subsequent dehydration and drying; when the amount is too small, the mechanical properties of the obtained natural rubber are poor. Therefore, under the premise of ensuring the coagulation, dehydration and drying effects of natural latex, the performance of the obtained natural rubber, cost control, and reduction of raw material waste are considered at the same time, and the mass proportion of the above-mentioned suitable natural rubber coagulation system is adopted.

[0037] After obtaining the diluted latex and the coagulant solution, the present invention mixes the diluted latex and the coagulant solution for aging to obtain the natural rubber. In the present invention, the mixing of the diluted latex and the coagulant solution preferably includes: mixing the diluted latex and the coagulant solution in a parallel flow manner. The mixing of the diluted latex and the coagulant solution is preferably carried out in a coagulation tank. In an embodiment of the present invention, the diluted latex and the coagulant solution are injected into the coagulation tank in a parallel flow manner. When the diluted latex and the coagulant solution are in parallel flow, they start to be injected into the coagulation tank at the same time, and the injection is completed at the same time. The aging time is preferably 8 to 12 hours, and can be 10 hours in the embodiment. The aging time is calculated from the moment when the diluted latex and the coagulant solvent are completely injected into the coagulation tank at the same time.

[0038] In the present invention, after the aging is completed, a coagulated product is obtained, and the present invention preferably further comprises: dehydrating and drying the coagulated product in sequence to obtain the natural rubber. The dehydration preferably comprises: thinning dehydration and crepe dehydration in sequence. The aging process is the coagulation process of the natural latex.

[0039] The present invention provides natural rubber prepared by the preparation method described in the above technical solution. The natural rubber prepared by the present invention greatly improves the flex resistance and aging resistance, and prolongs the shelf life of the natural rubber and the service life of the prepared tire.

[0040] The present invention provides the use of the natural rubber described in the above technical solution in preparing tire sidewall rubber.

[0041] The natural rubber prepared by the present invention has the advantages of high strength, flex resistance and aging resistance, is green and environmentally friendly, and can meet the use requirements of high-end tire sidewall rubber.

[0042] The present invention provides a tire sidewall rubber, comprising the following components in parts by mass:

[0043] The above technical scheme comprises 50-70 parts of natural rubber, 20-40 parts of EPDM, 5-15 parts of butadiene rubber, 30-50 parts of carbon black, 5-7 parts of aromatic oil, 4-6 parts of zinc oxide, 0.5-1.5 parts of stearic acid, 1-3 parts of protective wax, 3-5 parts of antioxidant, 0.5-1.5 parts of 203 resin, 1-2 parts of sulfur, 1-1.5 parts of accelerator, 0.1-1 parts of anti-reversion agent and 0.1-0.3 parts of scorch retarder.

[0044] In the present invention, the EPDM rubber is preferably EPDM J-4045. The butadiene rubber is preferably butadiene BR9000. The carbon black is preferably carbon black N330. The protective wax is preferably protective wax Okerin1900. The antioxidant preferably includes antioxidant S-TMQ and antioxidant 6PPD, and the mass ratio of the antioxidant S-TMQ and the antioxidant 6PPD is preferably 1:1. The sulfur is preferably insoluble sulfur IS-60. The accelerator is preferably accelerator NOBS. The anti-reversion agent is preferably anti-reversion agent WK-901. The anti-scorch agent is preferably anti-scorch agent CTP.

[0045] As a specific embodiment of the present invention, the tire sidewall rubber includes the following components in parts by mass:

[0046] The above technical solution comprises 60 parts of natural rubber, 30 parts of EPDM, 10 parts of butadiene rubber, 40 parts of carbon black, 6 parts of aromatic oil, 5 parts of zinc oxide, 1 part of stearic acid, 2 parts of protective wax, 4 parts of antioxidant, 1 part of 203 resin, 1.5 parts of sulfur, 1.3 parts of accelerator, 0.5 parts of anti-reversion agent and 0.2 parts of scorch retarder.

[0047] The present invention provides a rubber refining method for tire sidewall rubber according to the above technical solution, preferably comprising the following steps:

[0048] The natural rubber, EPDM and cis-1,4-butadiene rubber described in the above technical solution are first mixed to obtain a first mixture;

[0049] The first mixture, stearic acid, zinc oxide, protective wax, antioxidant and 203 resin are mixed for the second time to obtain a second mixture;

[0050] The second mixture, carbon black and aromatic oil are mixed for the third time to obtain a third mixture; the third mixture is discharged and parked in sequence to obtain a mixed rubber;

[0051] The first-stage mixed rubber, sulfur, accelerator, anti-reversion agent and anti-scorch agent are mixed for the fourth time to obtain a fourth mixture; and the fourth mixture is subjected to a second rubber discharge.

[0052] In the present invention, the first mixing, the second mixing, the third mixing and the fourth mixing are all carried out in an internal mixer, and the rotation speed of the internal mixer during the first mixing, the second mixing, the third mixing and the fourth mixing is preferably 50-60 r / min. The initial temperature of the internal mixer during the first mixing and the fourth mixing is preferably 50° C. The time of the first mixing is preferably 0-2 min, and is not 0. The time of the second mixing is preferably 2-5 min. The time of the third mixing is preferably 5-8 min. The time of the fourth mixing is preferably 0-3 min, and is not 0.

[0053] In the present invention, the vulcanization conditions of the tire sidewall rubber preferably include: the vulcanization temperature is preferably 143° C., and the time is preferably 45 minutes.

[0054] In order to further illustrate the present invention, the technical solutions provided by the present invention are described in detail below in conjunction with embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0055] Example 1

[0056] This embodiment provides a method for preparing natural rubber. This embodiment is industrialized and trial-produced on a production line, and specifically includes the following steps:

[0057] 1000kg of natural rubber latex, with a dry rubber content of 30wt%, i.e. 300kg of dry rubber, is diluted with water in a mixing tank to a dry rubber content of 25wt%, to obtain diluted latex in the mixing tank.

[0058] Accurately weigh 300 g of choline bitartrate and 300 g of citric acid, add them into the acid pool, stir with water to dissolve, and mix evenly to obtain a coagulant solution; then continue to add water to make the liquid level of the coagulant solution in the acid pool equal to the liquid level of the diluted latex in the mixing pool.

[0059] The diluted latex in the mixing tank and the coagulant solution in the acid tank flow into the coagulation tank at the same time, wherein the diluted latex and the coagulant solution are injected at the same time and injected at the same time; the natural latex is matured in the coagulation tank for 10 hours and completely coagulated, and then mechanically processed, that is, after thinning and dehydration, creping and dehydration and drying in sequence, natural rubber, i.e. raw rubber product, is obtained.

[0060] Example 2

[0061] This embodiment provides a method for preparing natural rubber. This embodiment is industrialized and trial-produced on a production line, and specifically includes the following steps:

[0062] 1000kg of natural rubber latex, with a dry rubber content of 30wt%, i.e. 300kg of dry rubber, is diluted with water in a mixing tank to a dry rubber content of 25wt%, to obtain diluted latex in the mixing tank.

[0063] Accurately weigh 300 g of choline dihydrogen citrate and 300 g of citric acid, add them into the acid pool, stir with water to dissolve, and mix evenly to obtain a coagulant solution; then continue to add water to make the liquid level of the coagulant solution in the acid pool equal to the liquid level of the diluted latex in the mixing pool.

[0064] The diluted latex in the mixing tank and the coagulant solution in the acid tank flow into the coagulation tank at the same time, wherein the diluted latex and the coagulant solution are injected at the same time and injected at the same time; the natural latex is matured in the coagulation tank for 10 hours and completely coagulated, and then mechanically processed, that is, after thinning and dehydration, creping and dehydration and drying in sequence, natural rubber, i.e. raw rubber product, is obtained.

[0065] Example 3

[0066] This embodiment provides a method for preparing natural rubber. This embodiment is industrialized and trial-produced on a production line, and specifically includes the following steps:

[0067] 1000kg of natural rubber latex, with a dry rubber content of 30wt%, i.e. 300kg of dry rubber, is diluted with water in a mixing tank to a dry rubber content of 25wt%, to obtain diluted latex in the mixing tank.

[0068] Accurately weigh 300 g of choline bitartrate and 300 g of malic acid, add them into the acid pool, stir with water to dissolve, and mix evenly to obtain a coagulant solution; then continue to add water to make the liquid level of the coagulant solution in the acid pool equal to the liquid level of the diluted latex in the mixing pool.

[0069] The diluted latex in the mixing tank and the coagulant solution in the acid tank flow into the coagulation tank at the same time, wherein the diluted latex and the coagulant solution are injected at the same time and injected at the same time; the natural latex is matured in the coagulation tank for 10 hours and completely coagulated, and then mechanically processed, that is, after thinning and dehydration, creping and dehydration and drying in sequence, natural rubber, i.e. raw rubber product, is obtained.

[0070] Example 4

[0071] This embodiment provides a method for preparing natural rubber. This embodiment is industrialized and trial-produced on a production line, and specifically includes the following steps:

[0072] 1000kg of natural rubber latex, with a dry rubber content of 30wt%, i.e. 300kg of dry rubber, is diluted with water in a mixing tank to a dry rubber content of 25wt%, to obtain diluted latex in the mixing tank.

[0073] Accurately weigh 300 g of choline dihydrogen citrate and 300 g of malic acid, add them into the acid tank, stir with water to dissolve, and mix evenly to obtain a coagulant solution; then continue to add water to make the liquid level of the coagulant solution in the acid tank equal to the liquid level of the diluted latex in the mixing tank.

[0074] The diluted latex in the mixing tank and the coagulant solution in the acid tank flow into the coagulation tank at the same time, wherein the diluted latex and the coagulant solution are injected at the same time and injected at the same time; the natural latex is matured in the coagulation tank for 10 hours and completely coagulated, and then mechanically processed, that is, after thinning and dehydration, creping and dehydration and drying in sequence, natural rubber, i.e. raw rubber product, is obtained.

[0075] Test Example 1

[0076] The performance of the natural rubber (i.e., the finished raw rubber) prepared in Examples 1 to 4 was tested. Specifically, the natural rubber prepared in Examples 1 to 4 was prepared into a mixed rubber according to the test formula in Table 1. The test formula of the mixed rubber is shown in Table 1, and the rubber mixing process is shown in Table 2. The comparison samples are domestic standard rubber SCR5 and Indonesian 1 # Smoked sheet rubber, the mixed rubber sheets prepared from the natural rubber obtained in Examples 1 to 4 are 5 groups of mixed rubber sheets (the formula dosage in Table 1), which correspond to the tensile strength test, elongation at break test, Mooney viscosity test, tear strength test, and compression fatigue temperature rise test in Table 3, respectively. The specific test results are shown in Table 3. The test method for tensile strength in Table 3 is GB / T 528-2009, the test method for elongation at break is GB / T 528-2009, the test method for Mooney viscosity is GB / T 1232.1-2016, the test method for tear strength is GB / T529-2008, and the test method for compression fatigue temperature rise is GB / T 1687.3-2016.

[0077] From the data in Table 3, it can be seen that the tensile strength and tear strength of the mixed rubber sheets obtained by the natural rubber products prepared in Examples 1 to 4 according to the test formula in Table 1 are higher than the domestic standard rubber SCR5 and reach the imported Indonesian 1 # The smoke sheet glue level is high, and the compression fatigue temperature rise is greatly reduced.

[0078] Table 1 Components and dosage of test formula

[0079] Raw material name Ratio (mass parts) Raw Rubber 100.00 Stearic acid 0.50 Zinc Oxide 6.00 Accelerator M 0.50 sulfur 3.50 total 110.50

[0080] Table 2 Rubber mixing process of the raw rubber formula in Table 1

[0081]

[0082]

[0083] Use open mixing mill for rubber mixing, with roller distance of 3mm. After adding materials according to Table 2, adjust the roller distance to 0mm and make three triangle packs. Then adjust the roller distance to 3mm to extrude a sample of about 3mm and leave it for more than 12 hours. After leaving it, pass it through thinly once, adjust the roller distance to 3mm, wrap the roller, make three cuts on each side, extrude a sample of about 3mm and test it.

[0084] Table 3 Performance test results of natural rubber prepared in Examples 1 to 4

[0085]

[0086] Note: The curing condition is 140℃×30min.

[0087] Test Example 2

[0088] The sidewall rubber formula performance test, the comparison samples are domestic standard rubber SCR5 and Indonesia 1# smoked sheet rubber, the specific sidewall rubber formula is shown in Table 4, the rubber mixing process is shown in Table 5, and the test results are shown in Table 6. In Table 6, the test method for tensile strength is GB / T 528-2009, the test method for elongation at break is GB / T528-2009, the test method for tear strength is GB / T 529-2008, the test method for 300% tensile stress is GB / T 528-2009, the test method for Shore A hardness is GB / T531.1-2004, the test method for flex cracking is GB / T 13934-2006, and the test method for compression fatigue temperature rise is GB / T1687.3-2016.

[0089] From the data in Table 6, it can be seen that the performance of the sidewall rubber obtained by the domestic natural rubber prepared in Examples 1 to 4 of the present invention is much higher than that of the domestic SCR5, and the tensile strength, elongation at break, tear strength, 300% tensile stress, hardness, flex cracking and compression fatigue temperature rise are close to those of the imported Indonesian 1# smoked sheet rubber. Compared with the domestic standard rubber, the natural rubber prepared in Examples 1 to 4 of the present invention can greatly improve the flex resistance and aging resistance of the sidewall rubber, is green and environmentally friendly, can meet the use requirements of high-end tire sidewall rubber, and replace imported smoked sheet rubber.

[0090] Table 4 Components and dosage in sidewall rubber formula

[0091]

[0092]

[0093] Table 5 Rubber mixing process of the sidewall rubber formula in Table 4

[0094]

[0095]

[0096] Internal mixer: initial temperature 50℃, speed 50r / min.

[0097] Table 6 Sidewall rubber formula test results

[0098] Test items Example 1 Example 2 Example 3 Example 4 SCR5 Indonesia 1# cigarette Tensile strength MPa 28.8 27.2 28.5 28.6 25.7 27.8 Elongation at break % 520 540 530 530 490 520 Tear strength KN / m 102 108 106 102 85 98 300% tensile stress MPa 14.0 14.9 14.4 14.5 12.1 14.5 Hardness Shore A 68 68 70 69 65 70 Flex cracking grade 6 6 6 6 4 5s Compression fatigue temperature rise ℃ 40 39 38 39 45 42

[0099] Note: Curing conditions: 143℃×45min.

[0100] It can be seen from the above embodiments that the present invention provides a natural rubber coagulation system, including a choline compound and an organic acid; the coagulation system provided by the present invention is compounded with an organic acid and a choline compound and applied to the preparation of natural rubber, which can keep the molecular structure of the rubber hydrocarbon from being destroyed, thereby greatly improving the strength of the natural rubber (including tensile strength, elongation at break, and tear strength), while improving the flexural resistance and aging resistance of the natural rubber, thereby extending the shelf life of the natural rubber and the service life of the tire.

[0101] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. Other embodiments can be obtained based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A natural rubber coagulation system, characterized in that: It comprises a choline compound and an organic acid; the mass ratio of the choline compound to the organic acid is (0.1-0.2): (0.1-0.2).

2. The natural rubber coagulation system according to claim 1, characterized in that: The choline compounds include choline bitartrate and / or choline dihydrogen citrate.

3. The natural rubber coagulation system according to claim 1 or 2, characterized in that: The organic acid includes citric acid and / or malic acid.

4. A method for preparing natural rubber, characterized in that: The following steps are involved: Mixing natural latex and water to obtain diluted latex; Mixing the natural rubber coagulation system according to any one of claims 1 to 3 with water to obtain a coagulant solution; The diluted latex and the coagulant solution are mixed and aged to obtain the natural rubber.

5. The preparation method according to claim 4, characterized in that: The natural latex is gel-free; the ammonia content in the natural latex is less than 0.05wt%; The dry rubber content of the diluted latex is 23-25wt%.

6. The preparation method according to claim 4 or 5, characterized in that: The mass percentage of the choline compound in the natural rubber coagulation system to the mass percentage of the dry rubber in the natural latex is 0.1-0.2%; The mass percentage of the organic acid in the natural rubber coagulation system to the mass percentage of the dry rubber in the natural latex is 0.1-0.2%.

7. The preparation method according to claim 4, characterized in that: The aging time is 8 to 12 hours.

8. The natural rubber prepared by the preparation method according to any one of claims 4 to 7.

9. Use of the natural rubber according to claim 8 in preparing tire sidewall rubber.

10. A tire sidewall rubber, characterized in that: The composition includes the following components in parts by weight: 50-70 parts of the natural rubber as described in claim 8, 20-40 parts of EPDM, 5-15 parts of butadiene rubber, 30-50 parts of carbon black, 5-7 parts of aromatic oil, 4-6 parts of zinc oxide, 0.5-1.5 parts of stearic acid, 1-3 parts of protective wax, 3-5 parts of antioxidant, 0.5-1.5 parts of 203 resin, 1-2 parts of sulfur, 1-1.5 parts of accelerator, 0.1-1 part of anti-reversion agent, and 0.1-0.3 part of scorch retarder.

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