A vulcanized rubber and a preparation method thereof

Abstract

The present invention relates to the technical field of rubber, and particularly relates to a vulcanized rubber and a preparation method thereof. The vulcanized rubber provided by the present invention, in parts by mass, comprises the following raw materials: 100 parts of deproteinized natural latex; 2.5 to 20 parts of a vulcanization accelerator; 0.05 to 5 parts of a functional auxiliary agent; 0.2 to 3 parts of sulfur; 2 to 7 parts of zinc oxide; the nitrogen content of the denitrified natural latex is 0.02 to 0.2 wt.%; the functional auxiliary agent comprises one or more of serine, arginine, lysine and glutamic acid. In the present invention, the functional auxiliary agent helps to promote the formation of a complex of Zn ions, promotes the dispersion and solubility of the complex in the rubber matrix, and the formed amine-containing complex can promote the ring opening and activation of sulfur elements, improving the utilization rate of zinc oxide and sulfur, promoting the construction of the rubber matrix network, reducing network defects, and thus improving the tensile properties and aging properties of the deproteinized natural latex.

Description

Technical Field

[0001] The present invention relates to the technical field of rubber, and particularly relates to a vulcanized rubber and a preparation method thereof. Background Art

[0002] The green biological source, excellent film strength, high elasticity and memory of natural rubber latex are irreplaceable by other materials, and it is the preferred material for inflatable elastic products such as medical appliances, catheters, tapes, tourniquets, gloves and condoms. However, natural rubber latex contains latex proteins that are skin sensitizing, and the allergic reaction problem caused by the proteins in the latex has become the biggest problem faced by medical natural rubber latex products. Research has found that among most people who often come into contact with natural rubber latex and its products, the number of allergic patients has reached an epidemic level. These individuals experience allergic reactions such as rhinitis, conjunctivitis, contact urticaria, and bronchial asthma when contacting the products, and even sudden death. At present, the available way to avoid the allergy to natural rubber latex proteins is to remove the proteins in natural rubber latex, that is, deproteinized natural rubber latex. However, at present, the deproteinized natural rubber latex has problems of poor tensile properties and anti-aging properties. Summary of the Invention

[0003] In order to solve the problems existing in the prior art, the present invention provides a vulcanized rubber and a preparation method thereof. The vulcanized rubber provided by the present invention has good tensile properties and anti-aging properties.

[0004] In order to achieve the above invention purpose, the present invention provides the following technical solutions:

[0005] The present invention provides a vulcanized rubber. Calculated by mass parts, the preparation raw materials include:

[0006]

[0007] The nitrogen content of the denitrified white natural rubber latex is 0.02 - 0.2 wt.%.

[0008] The functional auxiliary agent includes one or more of serine, arginine, lysine and glutamic acid.

[0009] Preferably, the vulcanization accelerator includes one or more of N-tert-butyl-2-benzothiazole sulfenamide, N-cyclohexyl-2-benzothiazole sulfenamide, 2-mercaptobenzothiazole and dibenzothiazole disulfide.

[0010] Preferably, the preparation of the deproteinized natural rubber latex includes the following steps:

[0011] (1) Mix natural rubber latex, urea and a stabilizer, and let the obtained mixture stand and then centrifuge to obtain a pretreated natural rubber latex;

[0012] (2) Dilute the pretreated natural latex. After mixing the obtained dilution with ammonia water and a stabilizer, centrifuge again to obtain deproteinized natural latex.

[0013] Preferably, the stabilizer is one or more of sodium dodecyl sulfonate, sodium petroleum sulfonate, Tween, and Peregal.

[0014] Preferably, in step (2), the ammonia water is 0.3 - 0.7% of the mass of the dilution.

[0015] Preferably, in step (2), the stabilizer is 0.2 - 0.6% of the mass of the dilution.

[0016] The present invention also provides a method for preparing the vulcanized rubber described in the above technical solution, including the following steps:

[0017] Mix the deproteinized natural latex and a functional auxiliary agent to obtain a modified deproteinized natural latex;

[0018] Mix the modified deproteinized natural latex, an emulsion of a vulcanization accelerator, an emulsion of sulfur, and an emulsion of zinc oxide. The obtained mixture is formed and dried to obtain a mixed dry rubber;

[0019] Carry out mixing and vulcanization on the mixed dry rubber in sequence to obtain the vulcanized rubber.

[0020] Preferably, the mixing method is stirring; the rotation speed of the stirring is 100 - 1000 rpm, and the stirring time is 10 - 60 min.

[0021] Preferably, the mixing is to mix the mixed dry rubber on a mixing roll at 40 - 70 °C for 20 - 60 times.

[0022] Preferably, the vulcanization temperature is 140 - 180 °C, the vulcanization pressure is 8 - 20 MPa, and the vulcanization time is 10 - 50 min.

[0023] The present invention provides a vulcanized rubber. By mass, the preparation raw materials include: 100 parts of deproteinized natural latex; 2.5 - 20 parts of a vulcanization accelerator; 0.05 - 5 parts of a functional auxiliary agent; 0.2 - 3 parts of sulfur; 2 - 7 parts of zinc oxide; the nitrogen content of the deproteinized natural latex is 0.02 - 0.2 wt.%; the functional auxiliary agent includes one or more of serine, arginine, lysine, and glutamic acid. The functional auxiliary agent in the vulcanized rubber provided by the present invention helps to promote the formation of a complex of Zn ions, promotes the dispersion and solubility of the complex in the rubber matrix, and the formed amine-containing complex can promote the ring opening and activation of sulfur elements, improving the utilization rates of zinc oxide and sulfur, promoting the construction of the rubber matrix network, reducing network defects, and thus improving the tensile properties and aging properties of the deproteinized natural latex. Description of the Drawings

[0024] Figure 1 For the analysis elements of C, N, S, and Zn under the scanning electron microscope and corresponding X-ray energy spectrum of deproteinized natural rubber UFNR;

[0025] Figure 2 For the analysis elements of C, N, S, and Zn under the scanning electron microscope and corresponding X-ray energy spectrum of A-0.9 vulcanized natural rubber. Detailed Embodiments

[0026] The present invention provides a vulcanized rubber. By mass parts, the preparation raw materials include:

[0027]

[0028] The nitrogen content of the denitrified natural latex is 0.02 - 0.2 wt.%;

[0029] The functional auxiliary agent includes one or more of serine, arginine, lysine, and glutamic acid.

[0030] As an embodiment, the vulcanized rubber includes 2.5 - 20 parts of vulcanization accelerator. In a specific embodiment, it can be 2.5 - 3.5 parts.

[0031] As an embodiment, the vulcanization accelerator includes one or more of N-tert-butyl-2-benzothiazole sulfenamide, N-cyclohexyl-2-benzothiazole sulfenamide, N,N-dicyclohexyl-2-benzothiazole sulfenamide, 2-mercaptobenzothiazole, and dibenzothiazole disulfide.

[0032] As an embodiment, the vulcanized rubber includes 0.05 - 5 parts of functional auxiliary agent. In a specific embodiment, it can be 0.2 - 3 parts. As an embodiment, the functional auxiliary agent includes one or more of serine, arginine, lysine, and glutamic acid.

[0033] As an embodiment, the vulcanized rubber includes 0.2 - 3 parts of sulfur. As another embodiment, the vulcanized rubber includes 0.8 - 2 parts of sulfur. In a specific embodiment, it can be 1 - 1.5 parts.

[0034] As an embodiment, the vulcanized rubber includes 2 - 7 parts of zinc oxide. As another embodiment, the vulcanized rubber includes 4 - 6 parts of zinc oxide. In a specific embodiment, it can be 5 parts.

[0035] As an embodiment, the vulcanized rubber includes 100 parts of deproteinized natural latex; the nitrogen content in the deproteinized natural latex is 0.02 - 0.2 wt.%. In a specific embodiment, the nitrogen content can be 0.1 wt.%.

[0036] As an implementation method, the preparation of the deproteinized natural latex includes the following steps:

[0037] (1) Mix natural latex, urea, and a stabilizer, and let the resulting mixture stand still and then centrifuge it successively to obtain pretreated natural latex;

[0038] (2) Dilute the pretreated natural latex, mix the resulting dilution with ammonia water and a stabilizer, and then centrifuge it again to obtain deproteinized natural latex.

[0039] In the present invention, natural latex, urea, and a stabilizer are mixed, and the resulting mixture is allowed to stand still and then centrifuged successively to obtain pretreated natural latex.

[0040] As an implementation method, the stabilizer is one or more of sodium dodecyl sulfate (SDS), sodium petroleum sulfonate, Tween, and Peregal, the Tween is Tween-100, and the Peregal is Peregal O-20.

[0041] In a specific embodiment, the SDS is used in the form of an SDS solution, and the mass concentration of the SDS solution is 10%.

[0042] As an implementation method, the mass fraction of urea in the mixture is 0.05 - 0.2%, and in a specific embodiment, it can be 0.1%; as an implementation method, the mass fraction of the stabilizer in the mixture is 0.05 - 2%, and in a specific embodiment, it can be 0.25%.

[0043] As an implementation method, the standing still is carried out at room temperature for 0.5 - 4 h, and in a specific embodiment, the standing still is carried out at room temperature for 1 h. As an implementation method, in a specific embodiment, the rotation speed of the centrifugation can be 7700 rpm.

[0044] In the present invention, the pretreated natural latex is diluted, the resulting dilution is mixed with ammonia water and a stabilizer, and then centrifuged again to obtain deproteinized natural latex.

[0045] As an implementation method, the reagent used for dilution is water, and the volume of the dilution is 2 times the volume of the pretreated natural latex.

[0046] As an implementation method, the ammonia water is 0.1 - 0.7% of the mass of the dilution, and in a specific embodiment, the ammonia water is 0.5% of the mass of the dilution; as an implementation method, the stabilizer is 0.2 - 0.6% of the mass of the dilution, and in a specific embodiment, the stabilizer is 0.2% of the mass of the dilution.

[0047] As an implementation manner, the rotational speed of the re - centrifugation is 7700 rpm.

[0048] The present invention also provides a preparation method of the vulcanized rubber as described in the above - mentioned technical solution, including the following steps:

[0049] Mix the de - proteinized natural latex and the functional auxiliary agent to obtain a modified de - proteinized natural latex;

[0050] Mix the modified de - proteinized natural latex, the emulsion of the vulcanization accelerator, the emulsion of sulfur, and the emulsion of zinc oxide, and perform shaping and drying on the obtained mixture to obtain a mixed dry rubber;

[0051] Carry out mixing and vulcanization on the mixed dry rubber in sequence to obtain the vulcanized rubber.

[0052] The present invention mixes the de - proteinized natural latex and the functional auxiliary agent to obtain a modified de - proteinized natural latex.

[0053] As an implementation manner, the functional auxiliary agent is used in the form of a solution of the functional auxiliary agent. As an implementation manner, the mass concentration of the solution of the functional auxiliary agent is 10 - 20%.

[0054] After obtaining the modified de - proteinized natural latex, the present invention mixes the modified de - proteinized natural latex, the emulsion of the vulcanization accelerator, the emulsion of sulfur, and the emulsion of zinc oxide, and performs shaping and drying on the obtained mixture to obtain a mixed dry rubber.

[0055] As an implementation manner, the mass concentration of the emulsion of the vulcanization accelerator is 20 - 40%, and in a specific embodiment, it can be 30%; the mass concentration of the emulsion of sulfur is 30 - 50%, and in a specific embodiment, it can be 40%; the mass concentration of the emulsion of zinc oxide is 30 - 50%, and in a specific embodiment, it can be 40%.

[0056] As an implementation manner, the mixing method is stirring, the rotational speed of the stirring is 100 - 1000 rpm, the stirring time is 10 - 60 min. In a specific embodiment, the rotational speed of the stirring is 250 rpm and the time is 30 min. In a specific embodiment, the shaping and drying is to lay the mixed material on two glass plates and then dry it at room temperature.

[0057] After obtaining the mixed dry rubber, the present invention carries out mixing and vulcanization on the mixed dry rubber in sequence to obtain the vulcanized rubber.

[0058] As an implementation manner, the kneading is to knead the mixed dry rubber on a kneading roll at 40 - 70°C for 20 - 60 times. In a specific embodiment, the kneading is to knead the mixed dry rubber on a kneading roll at 40 - 70°C for 40 times. As an implementation manner, the roll gap of the kneading roll is 0.1 - 0.5 mm.

[0059] As an implementation manner, the temperature of vulcanization is 140 - 180°C, the pressure of vulcanization is 8 - 20 MPa, and the time of vulcanization is 10 - 50 min. In a specific embodiment, the temperature of vulcanization is 150°C, the pressure of vulcanization is 15 MPa, and the time of vulcanization is 20 min.

[0060] The technical solutions provided by the present invention will be described in detail below in conjunction with embodiments, but they cannot be understood as limiting the protection scope of the present invention.

[0061] Embodiment 1

[0062] 15 kg of fresh natural rubber latex is taken and urea and 10 wt% SDS solution are added. After mixing evenly, a mixed solution is obtained. The mass fraction of urea in the mixed solution is 0.1%, and the mass fraction of SDS is 0.25%.

[0063] After the obtained mixed solution is left standing at room temperature for 1 h, it is centrifuged on a disc centrifuge (rotation speed: 7700 rpm) to obtain a centrifuged sample;

[0064] The centrifuged sample is diluted to twice its original mass to obtain a dilution; after adding ammonia water and 10 wt.% SDS solution to the dilution (the mass of added ammonia water is 0.5% of the mass of the dilution, and the mass of SDS is 0.2% of the mass of the dilution), it is centrifuged again to obtain deproteinized natural rubber latex, denoted as UFNR.

[0065] 20 wt.% serine solution is added to 100 parts by mass of UFNR and stirred for 10 min (wherein, the mass fraction of serine in the serine solution is 0.75 part relative to UFNR) to obtain modified UFNR;

[0066] The obtained modified UFNR is mixed with an emulsion containing 1.5 parts by mass of N-tert-butyl-2-benzothiazole sulfenamide (the mass concentration of N-tert-butyl-2-benzothiazole sulfenamide in the emulsion is 30%), an emulsion containing 1.5 parts by mass of sulfur (the mass concentration of sulfur in the emulsion is 40%), and an emulsion containing 5 parts by mass of zinc oxide (the mass concentration of zinc oxide in the emulsion is 40%). After stirring for 30 min under the condition of a rotation speed of 250 rpm, it is spread on two glass plates (large plate size: 24.5×15 cm, small plate size: 15×13 cm) and dried at room temperature to obtain mixed dry rubber.

[0067] The mixed dry glue was passed through a mixing roll (roll gap: 0.2 mm) 30 times at 70 °C. After mixing, it was left standing for 16 h to obtain a mixed rubber.

[0068] An MDR-2000E type non-rotor vulcanization instrument was used to determine the optimum vulcanization time of the mixed rubber at a vulcanization temperature of 150 °C. Then, the mixed rubber was cut into square rubbers of about 22 g, and heat vulcanization was carried out using an XLB-D type flat vulcanizing machine (vulcanization temperature: 150 °C, time: 20 min, pressure: 15 MPa) to produce a vulcanized rubber film of 14×12 cm (denoted as LS-0.75).

[0069] Example 2

[0070] The difference from Example 1 is only that the mass fraction of serine in the serine solution is 1.5 parts relative to UFNR, and the vulcanized rubber film is denoted as LS-1.5.

[0071] Example 3

[0072] The difference from Example 1 is only that the mass fraction of serine in the serine solution is 2.25 parts relative to UFNR, and the vulcanized rubber film is denoted as LS-2.25.

[0073] Example 4

[0074] The difference from Example 1 is only that the mass fraction of serine in the serine solution is 3 parts relative to UFNR, and the vulcanized rubber film is denoted as LS-3.

[0075] Example 5

[0076] The difference from Example 1 is only that the mass fraction of serine in the serine solution is 3.75 parts relative to UFNR, and the vulcanized rubber film is denoted as LS-3.75.

[0077] Example 6

[0078] Urea and a 10 wt.% SDS solution were added to 15 kg of fresh natural rubber latex and mixed evenly to obtain a mixed solution. The mass fraction of urea in the mixed solution was 0.1%, and the mass fraction of SDS was 0.25%.

[0079] After the obtained mixed solution was left standing at room temperature for 1 h, it was centrifuged on a disc centrifuge (rotation speed: 7700 rpm) to obtain a centrifuged sample.

[0080] The centrifuged sample was diluted to twice its original mass to obtain a dilution; after adding ammonia water and 10 wt.% SDS solution to the dilution (the mass of added ammonia water was 0.5% of the mass of the dilution, and the mass of SDS was 0.2% of the mass of the dilution), it was centrifuged again to obtain deproteinized natural latex, denoted as UFNR.

[0081] To 100 parts by mass of UFNR, 12.9 wt.% arginine solution was added and stirred for 10 min (wherein, the mass fraction of arginine in the arginine solution was 0.3 parts relative to UFNR) to obtain modified UFNR;

[0082] The obtained modified UFNR was mixed with an emulsion containing 1.5 parts by mass of N-tert-butyl-2-benzothiazole sulfenamide (the mass concentration of N-tert-butyl-2-benzothiazole sulfenamide in the emulsion was 30%), an emulsion containing 1.5 parts by mass of sulfur (the mass concentration of sulfur in the emulsion was 40%), and an emulsion containing 5 parts by mass of zinc oxide (the mass concentration of zinc oxide in the emulsion was 40%). After stirring for 30 min under the condition of a rotation speed of 250 rpm, it was spread on two glass plates (the size of the large plate: 24.5×15 cm, the size of the small plate: 15×13 cm) and dried at room temperature to obtain a mixed dry rubber.

[0083] The mixed dry rubber was passed through a mixing roll (roll gap was 0.2 mm) 30 times at 70 °C. After mixing, it was left standing for 16 h to obtain a mixed rubber;

[0084] Using an MDR-2000E type non-rotor vulcanization instrument to measure the optimum vulcanization time of the mixed rubber under the condition of a vulcanization temperature of 150 °C. Then, the mixed rubber was cut into square rubbers of about 22 g and vulcanized by heating using an XLB-D type flat vulcanizer (vulcanization temperature was 150 °C, time was 20 min, pressure was 15 MPa) to make a vulcanized rubber film of 14×12 cm (denoted as A-0.3).

[0085] Example 7

[0086] The difference from Example 1 was only that: the mass fraction of arginine in the arginine solution was 0.6 parts relative to UFNR, and the vulcanized rubber film was denoted as A-0.6.

[0087] Example 8

[0088] The difference from Example 1 was only that: the mass fraction of arginine in the arginine solution was 0.9 parts relative to UFNR, and the vulcanized rubber film was denoted as A-0.9.

[0089] Example 9

[0090] The difference from Example 1 is only that: the mass fraction of arginine in the arginine solution is 1.2 parts relative to UFNR, and the vulcanized rubber film is denoted as A-1.2.

[0091] Example 10

[0092] The difference from Example 1 is only that: the mass fraction of arginine in the arginine solution is 1.5 parts relative to UFNR, and the vulcanized rubber film is denoted as A-1.5.

[0093] Comparative Example 1

[0094] 15 kg of fresh natural latex is taken and urea and 10 wt.% SDS solution are added. After mixing evenly, a mixed solution is obtained. The mass fraction of urea in the mixed solution is 0.1%, and the mass fraction of SDS is 0.25%.

[0095] After the obtained mixed solution is left standing at room temperature for 1 h, it is centrifuged on a disc centrifuge (rotation speed: 7700 rpm) to obtain a centrifuged sample;

[0096] The centrifuged sample is diluted to twice its original mass to obtain a dilution; after adding ammonia water and 10 wt.% SDS solution to the dilution (the mass of the added ammonia water is 0.5% of the mass of the dilution, and the mass of SDS is 0.2% of the mass of the dilution), it is centrifuged again to obtain deproteinized natural latex, denoted as UFNR.

[0097] In the present invention, SEM tests were carried out on UFNR and A-0.9 vulcanized natural rubber. The test steps were as follows: the film was brittle fractured with liquid nitrogen, and then put into an ion sputtering instrument of model E-1045 of Hitachi High-Technologies Corporation to spray a metal film in vacuum to eliminate the charging phenomenon, and then put into a scanning electron microscope (SEM) of model S-4800 of Hitachi High-Technologies Corporation for testing. Elemental analysis of the sample was carried out by an energy dispersive X-ray spectrometer (EDS) of model Z230 Workstation of EDAX Company of the United States. Figure 1 For the analysis of elements C, N, S, and Zn in the scanning electron microscope and the corresponding X-ray energy spectrum of deproteinized vulcanized natural rubber UFNR Figure 2 For the analysis of elements C, N, S, and Zn in the scanning electron microscope and the corresponding X-ray energy spectrum of A-0.9 vulcanized natural rubber. From Figures 1-2It can be seen that by observing under a scanning electron microscope (SEM) at a magnification of 5K, there are a large number of aggregated particles in the deproteinized sulfurized natural rubber, and the size of these particles decreases significantly after adding the additives. This indicates that the addition of arginine helps to disperse the particles of the vulcanizing agent in the rubber. It can be found that most of the vulcanized rubber is composed of carbon and sulfur elements, with a small amount of nitrogen and zinc elements. Nitrogen can be well dispersed in the vulcanized rubber. Sulfur is initially in an aggregated state and becomes evenly dispersed after adding arginine, indicating that arginine can promote the dispersion of sulfur during the vulcanization process, enabling sulfur to crosslink better with the rubber molecular chains. Zinc also shows a similar dispersion situation in the rubber, indicating that the addition of the functional additive improves the construction efficiency of sulfur and zinc elements in the rubber matrix network, reduces network defects, and thus enhances the performance of the sulfurized natural rubber.

[0098] Test:

[0099] (1) Determination of mechanical properties

[0100] The samples were tested using an AI-7000-SU1 type electronic tensile testing machine from High-Speed Rail Testing Instruments (Dongguan) Co., Ltd. According to the GB / T528-2009 standard, the tensile test was carried out at a rate of 500 mm / min; according to the GB / T529-2008 standard, the tear strength was measured at a rate of 500 mm / min.

[0101] Table 1 Mechanical properties of deproteinized sulfurized natural rubber and sulfurized natural rubber with serine added

[0102]

[0103] As can be seen from Table 1: For the sulfurized natural rubber with serine added, in terms of tensile strength, the LS-3.75 vulcanized rubber has the highest tensile strength. The other vulcanized rubbers with serine added are all better than the deproteinized sulfurized natural rubber and increase with the increase in content. However, the addition of serine has a relatively small impact on the tear strength of natural rubber, and in some cases, the performance decreases. This may be due to the poor compatibility of serine in natural rubber, resulting in different actual addition amounts of serine in natural rubber, and thus different effects on the mechanical properties of natural rubber.

[0104] Table 2 Mechanical properties of deproteinized sulfurized natural rubber and sulfurized natural rubber with arginine added

[0105]

[0106]

[0107] As can be seen from Table 2: (1) The tensile strength of the vulcanizate with 0.9 parts of arginine added is the highest. After adding arginine, the tensile strength of the vulcanizate increases. With the increase in the nitrogen content of arginine, the tensile strength shows a trend of first increasing and then decreasing, increasing from 27.34 MPa to 33.34 MPa, with an increase of 6 MPa. (2) The 100% and 300% modulus at 100% elongation of natural rubber both increase, with the highest increases being 0.12 MPa and 0.23 MPa respectively. (3) The elongation at break of the vulcanizate increases by up to 30%. (4) The tear strength shows a similar trend to the tensile strength. With the increase in the nitrogen content of arginine, the tear strength of the vulcanizate first increases and then decreases, and is significantly higher than that of UFNR, with a maximum of 33.34 kN / m. (5) After adding arginine, the modulus at 100% elongation, tensile strength and tear strength of the vulcanizate are significantly improved. The comprehensive properties of the natural rubber vulcanizate with 0.9 and 1.2 parts of arginine added are the best.

[0108] Table 3 Aging properties and retention rates of deproteinized vulcanized natural rubber and vulcanized natural rubber with serine added

[0109]

[0110] As can be seen from Table 3: After aging, the tensile strength, 100% modulus at 100% elongation, and 300% modulus at 100% elongation of the vulcanized natural rubber with serine added all increase, increasing with the increase in serine content, by 9.61 MPa, 0.14 MPa and 0.51 MPa respectively.

[0111] Except for the vulcanizate with 0.75 parts of serine added, the tensile strength retention rates of other vulcanizates increase, with LS-3.0 having the highest increase of 30.04%. The elongation at break retention rates of the vulcanizates with serine added are all better than those of the deproteinized ones, indicating that the aging properties of the rubber are improved. It can also be shown that the addition of serine has an anti-aging effect on natural rubber.

[0112] (2) Determination of the aging properties of vulcanizates

[0113] Samples were cut according to the standard of GB / T528-2009. The test strips were aged in a UA-2071A type aging machine of Youken Technology Co., Ltd. at 100 °C for 24 h. After standing for 1 day, the properties of the vulcanizates after hot air aging were tested. The aged test strips were subjected to a tensile test, using the same method as the mechanical property test.

[0114] Table 4 Aging properties and retention rates of deproteinized vulcanized natural rubber and vulcanized natural rubber with arginine added

[0115]

[0116] As can be seen from Table 4: After aging, the tensile strength of the vulcanizate first increases and then decreases with the increase of arginine content. The vulcanizate with 0.9 parts of arginine has the maximum tensile strength and modulus at a specified elongation, which are increased by 6.27 MPa, 0.04 MPa and 0.09 MPa respectively, indicating that when 0.9 parts of arginine are added, the mechanical properties of the vulcanizate after aging are the best. The tensile strength, modulus at a specified elongation, retention rate of tensile strength and retention rate of elongation at break are all higher than those of the deproteinized vulcanizate after adding arginine, indicating that the aging performance of natural rubber with added arginine is improved, and arginine has an anti-aging effect in natural rubber.

[0117] Although the above embodiments have described the present invention in detail, they are only a part of the embodiments of the present invention, rather than all embodiments. Other embodiments can be obtained based on these embodiments without creative efforts, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A vulcanized rubber, characterized in that: In terms of mass fractions, the raw materials for preparation are specifically: The nitrogen content of the deproteinized natural rubber latex is 0.02-0.2 wt.%; The functional auxiliary agent is serine; The preparation of the deproteinized natural rubber latex comprises the following steps: (1) mixing natural rubber latex, urea and a stabilizer, and sequentially standing and centrifuging the resulting mixed solution to obtain a pretreated natural rubber latex; (2) diluting the pretreated natural rubber latex, mixing the obtained dilution with ammonia water and a stabilizer, and centrifuging again to obtain deproteinized natural rubber latex.

2. The vulcanized rubber according to claim 1, characterized in that The vulcanization accelerator includes one or more of N-tert-butyl-2-benzothiazole sulfenamide, N-cyclohexyl-2-benzothiazole sulfenamide, N,N-dicyclohexyl-2-benzothiazole sulfenamide, 2-mercaptobenzothiazole and dibenzothiazole disulfide.

3. The vulcanized rubber according to claim 1, characterized in that The stabilizer is one or more of sodium dodecyl sulfonate, sodium petroleum sulfonate, Tween and pyralidone.

4. The vulcanized rubber according to claim 1, characterized in that In step (2), the ammonia water accounts for 0.1 to 0.7% of the mass of the diluent.

5. The vulcanized rubber according to claim 1, characterized in that In step (2), the stabilizer is 0.2-0.6% of the mass of the diluent.

6. The method for preparing vulcanized rubber according to any one of claims 1 to 5, characterized in that: The following steps are involved: Mixing deproteinized natural rubber latex and functional additives to obtain modified deproteinized natural rubber latex; The modified deproteinized natural rubber latex, the emulsion of the vulcanization accelerator, the emulsion of sulfur and the emulsion of zinc oxide are mixed, and the obtained mixture is molded and dried to obtain a mixed dry rubber; The mixed dry rubber is kneaded and vulcanized in sequence to obtain the vulcanized rubber.

7. The preparation method according to claim 6, characterized in that: The mixing method is stirring; the stirring speed is 100 to 1000 rpm, and the stirring time is 10 to 60 minutes.

8. The preparation method according to claim 6, characterized in that: The mixing is to mix the mixed dry rubber at 40-70° C. for 20-60 times through a mixing roller.

9. The preparation method according to claim 6, characterized in that: The vulcanization temperature is 140-180° C., the vulcanization pressure is 8-20 MPa, and the vulcanization time is 10-50 min.

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