Electromagnetic shielding silicone rubber composite material with high wave absorbing property and preparation method thereof

Abstract

The invention relates to an electromagnetic shielding silicone rubber composite material with high wave absorbing property and a preparation method thereof, and belongs to the technical field of electromagnetic functional composites.The electromagnetic shielding silicone rubber composite material is prepared from, by weight, 94-99.5 parts of liquid silicone rubber and 0.5-6 parts of modified short carbon fibers; the length of the modified short carbon fiber is 0.1-5mm, the diameter of the modified short carbon fiber is 4-10mu m, the liquid silicone rubber is double-component addition type liquid silicone rubber, and the modified carbon fiber can be mixed with the liquid silicone rubber through simple mechanical stirring or a power mixer. The prepared electromagnetic shielding silicone rubber composite material not only maintains the inherent flexibility and elasticity (the elongation at break is greater than 300%) of silicone rubber, but also has low density (the density is less than 1.15 g / cm < 3 >) and wide-frequency-domain (2-40GHz) wave-absorbing property, and can be applied to the fields of aerospace, artificial intelligence, new energy and the like as a flexible electromagnetic shielding material.

Description

Technical Field

[0001] The present invention belongs to the technical field of electromagnetic functional composite materials, and specifically relates to an electromagnetic shielding silicone rubber composite material with high wave absorption and a preparation method thereof, which is particularly suitable for the fields of electromagnetic protection of flexible electronic devices and shielding of high-frequency communication equipment. Background Art

[0002] With the popularization of high-frequency electronic technologies such as 5G communications and millimeter-wave radar, electromagnetic pollution has expanded from the MHz level to the GHz level (10-40GHz). Electromagnetic shielding materials need to achieve breakthroughs in lightweight, broadband absorption (covering 6-40GHz), flexibility (such as adapting to dynamic bending and complex surfaces) and multi-functional integration (flame retardant, weather resistant, and waterproof) to meet the higher requirements of electromagnetic shielding materials put forward by increasingly miniaturized smart electronic devices.

[0003] Although traditional metal-based materials (such as copper and aluminum alloys) have excellent shielding performance, their high density (>3g / cm 3 ), low ductility (elongation at break <5%), and susceptibility to corrosion make it difficult to meet the lightweight and flexible packaging requirements of modern equipment. Existing silicone rubber-based electromagnetic shielding composite materials rely on high filler loadings (conductive / magnetic fillers often account for more than 30-60wt%), resulting in high density and difficulty maintaining the inherent flexibility and mechanical properties of silicone rubber, with tensile strength attenuation exceeding 50% and elongation at break <100%.

[0004] As an ideal electromagnetic shielding filler, chopped carbon fiber has the characteristics of light weight (density 1.6-1.8g / cm 3 ), excellent electrical conductivity (conductivity 10 4 -10 5 S / m) and high aspect ratio (50-1000), can significantly improve the electromagnetic shielding effectiveness of composite materials by constructing a three-dimensional conductive network. However, in actual application, due to the chemical inertness of the carbon fiber surface and the strong van der Waals force, the fibers are easily entangled and agglomerated, forming micron-sized aggregates, which makes it difficult to achieve single-fiber uniform dispersion in the liquid silicone rubber matrix. In response to this application difficulty, it is urgent to achieve coordinated optimization of electromagnetic loss performance, mechanical strength and environmental tolerance at low filler dosage through material design and process innovation, so as to adapt to the stringent requirements of emerging scenarios such as high-frequency flexible electronics and micro radar stealth components. Summary of the Invention

[0005] The object of the present invention is to provide an electromagnetic shielding silicone rubber composite material with high wave absorption and a preparation method thereof, so as to produce a lightweight, soft, and highly wave absorption electromagnetic shielding material.

[0006] On the one hand, the electromagnetic shielding silicone rubber composite material with high wave absorption provided by the present invention adopts the following technical solution:

[0007] The electromagnetic shielding silicone rubber composite material with high wave absorption comprises the following raw material components in parts by weight: 94-99.5 parts of liquid silicone rubber and 0.5-6 parts of modified chopped carbon fibers.

[0008] Preferably, the preparation steps of the modified chopped carbon fiber are as follows:

[0009] 1) washing the chopped carbon fibers with 2 wt% sodium hydroxide solution, 2 wt% nitric acid solution, and anhydrous ethanol, respectively;

[0010] 2) mixing an ethanol aqueous solution and a silane coupling agent to obtain a mixed solution, and placing the chopped carbon fibers obtained by the treatment in step 1) into the mixed solution for modification to obtain modified chopped carbon fibers;

[0011] The modified chopped carbon fibers have a length of 0.1-5 mm and a diameter of 4-10 μm.

[0012] Preferably, the general formula of the silane coupling agent in step 2) is RSi(OR')3;

[0013] The R group in the silane coupling agent includes any one of octyl, amino, epoxy, mercapto, 3-mercaptopropyl, 3-aminopropyl, aniline methyl, vinyl, 3-(methacryloyloxy)propyl, aminopropyl, and γ-glycidyloxypropyl;

[0014] The R' group in the silane coupling agent includes any one of methyl, ethyl, propyl, β-methoxyethoxy, methoxy, and ethoxy.

[0015] Preferably, the liquid silicone rubber is a two-component addition-type liquid rubber with a viscosity of 2000-4000 Pa·s.

[0016] Preferably, the density of the electromagnetic shielding silicone rubber composite material is less than 1.15 g / cm 3 , tensile strength at break > 4.2MPa, elongation at break > 300%, Shore A hardness adjustable in the range of 30-60 degrees, electromagnetic shielding effectiveness in the frequency domain of 2-40GHz > 50dB, and wave absorption rate > 80%.

[0017] On the other hand, the present invention also provides a method for preparing an electromagnetic shielding silicone rubber composite material with high wave absorption, comprising the following preparation steps:

[0018] S1, respectively with modified chopped carbon fiber and liquid silicone rubber, the modified chopped carbon fiber is placed in the liquid silicone rubber and mechanically stirred to obtain a mixed rubber material;

[0019] S2. Curing the mixed rubber material obtained in step S1 at room temperature or vulcanizing it at medium temperature on a flat vulcanizer to obtain an electromagnetic shielding silicone rubber composite material with high wave absorption.

[0020] 8. Preferably, the mass fraction of ethanol in the ethanol aqueous solution in step S1 is 5-100%;

[0021] The mass ratio of the ethanol aqueous solution, the silane coupling agent and the carbon fiber is 100:(0.5-15):1.

[0022] Preferably, in step S3, the mass ratio of the modified chopped carbon fiber to the liquid silicone rubber is (0.5-6): (94-99.5).

[0023] Preferably, in step S4, the molding vulcanization temperature is 100-150° C., the vulcanization time is 5-20 min, and the pressure is 10-15 MPa.

[0024] In summary, the present invention has the following beneficial technical effects:

[0025] 1. The raw materials of the electromagnetic shielding silicone rubber composite material with high wave absorption of the present invention include chopped carbon fibers and liquid silicone rubber. The synthesis process is simple. Room temperature addition-type liquid silicone rubber is used, which is non-toxic and harmless. The preparation process is simple and easy to mass produce. By surface modifying the chopped carbon fibers, the interface compatibility between the chopped carbon fibers and the liquid silicone rubber is enhanced, so that the chopped carbon fibers can be evenly dispersed in the liquid silicone rubber.

[0026] 2. The chopped carbon fibers used in the present invention can be waste materials of varying lengths produced due to processing losses, defective products, or scraps, and are widely available and inexpensive.

[0027] 3. The silicone rubber composite material prepared by the present invention maintains the inherent flexibility and elasticity of silicone rubber, and achieves efficient shielding of broadband electromagnetic waves (2-40GHz) at a low filling amount (0.5-6 parts), and the shielding mechanism is mainly wave absorption.

[0028] 4. The electromagnetic shielding silicone rubber composite material prepared by the present invention has a low density (less than 1.15g / cm 3 ), excellent mechanical properties, tensile strength>4.2MPa, elongation at break>300%, can meet the diverse needs of application fields such as consumer electronic devices, new energy vehicles, aviation and drones. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 (a) is a graph showing the electromagnetic shielding effectiveness of the electromagnetic shielding silicone rubber composite material of Example 1 of the present invention in the 8-12.4 GHz frequency band.

[0030] Figure 1(b) is a graph showing the electromagnetic shielding effectiveness of the electromagnetic shielding silicone rubber composite material of Example 1 of the present invention in the 12-18 GHz frequency band.

[0031] Figure 1 (c) is a graph showing the electromagnetic shielding effectiveness of the electromagnetic shielding silicone rubber composite material of Example 1 of the present invention in the 18-26.5 GHz frequency band.

[0032] Figure 1 (d) is a graph showing the electromagnetic shielding effectiveness of the electromagnetic shielding silicone rubber composite material of Example 1 of the present invention in the 26.5-40 GHz frequency band.

[0033] Figure 2 (a) is a graph showing the electromagnetic shielding effectiveness of the electromagnetic shielding silicone rubber composite material of Example 2 of the present invention in the 8-12.4 GHz frequency band.

[0034] Figure 2 (b) is a graph showing the electromagnetic shielding effectiveness of the electromagnetic shielding silicone rubber composite material of Example 2 of the present invention in the 12-18 GHz frequency band.

[0035] Figure 2 (c) is a graph showing the electromagnetic shielding effectiveness of the electromagnetic shielding silicone rubber composite material of Example 2 of the present invention in the 18-26.5 GHz frequency band.

[0036] Figure 2 (d) is a graph showing the electromagnetic shielding effectiveness of the electromagnetic shielding silicone rubber composite material of Example 2 of the present invention in the 26.5-40 GHz frequency band.

[0037] Figure 3 (a) is a graph showing the electromagnetic shielding effectiveness of the electromagnetic shielding silicone rubber composite material of Example 3 of the present invention in the 8-12.4 GHz frequency band.

[0038] Figure 3 (b) is a graph showing the electromagnetic shielding effectiveness of the electromagnetic shielding silicone rubber composite material of Example 3 of the present invention in the 12-18 GHz frequency band.

[0039] Figure 3 (c) is a graph showing the electromagnetic shielding effectiveness of the electromagnetic shielding silicone rubber composite material of Example 3 of the present invention in the 18-26.5 GHz frequency band.

[0040] Figure 3 (d) is a graph showing the electromagnetic shielding effectiveness of the electromagnetic shielding silicone rubber composite material of Example 3 of the present invention in the 26.5-40 GHz frequency band.

[0041] Figure 4 (a) is a graph showing the electromagnetic shielding effectiveness of the electromagnetic shielding silicone rubber composite material of Example 4 of the present invention in the 8-12.4 GHz frequency band.

[0042] Figure 4 (b) is a graph showing the electromagnetic shielding effectiveness of the electromagnetic shielding silicone rubber composite material of Example 4 of the present invention in the 12-18 GHz frequency band.

[0043] Figure 4 (c) is a graph showing the electromagnetic shielding effectiveness of the electromagnetic shielding silicone rubber composite material of Example 4 of the present invention in the 18-26.5 GHz frequency band.

[0044] Figure 4 (d) is a graph showing the electromagnetic shielding effectiveness of the electromagnetic shielding silicone rubber composite material of Example 4 of the present invention in the 26.5-40 GHz frequency band. DETAILED DESCRIPTION

[0045] The following is a combination of the embodiments and the appended Figure 1-4 The present invention is described in further detail.

[0046] Example 1

[0047] Electromagnetic shielding silicone rubber composite material with high wave absorption, and preparation method thereof:

[0048] T1. Take 2wt% sodium hydroxide solution, 2wt% nitric acid solution and anhydrous ethanol respectively, take chopped carbon fibers and soak them in the above three solutions in sequence. Soak the chopped carbon fibers in each solution for 3 minutes. Take out the chopped carbon fibers and wash away the residual solution on the surface of the chopped carbon fibers with pure water.

[0049] T2, taking 10 ml of silane coupling agent RSi(OR')3 (R is octyl, R' is methyl) and 100 ml of anhydrous ethanol, stirring and mixing to obtain a mixed solution, taking 1 g of the chopped carbon fiber obtained by the treatment in T1) and placing it into the mixed solution for modification, stirring for 30 minutes, ultrasonicating for 20 minutes, continuing to stir for 3 minutes, filtering and drying to obtain modified carbon fiber;

[0050] T3, taking 95 parts of liquid silicone rubber, which is a commercially available two-component addition-type liquid silicone rubber with a viscosity of 2000-4000 Pa·s, and taking 5 parts of the modified carbon fiber prepared in step T2, placing them in the liquid silicone rubber and stirring at high speed to mix them so that the modified carbon fiber is evenly mixed in the liquid silicone rubber to obtain a mixture;

[0051] T4. Pour the mixture obtained in step T3 into an iron mold, place it in a flat vulcanizer, and perform a vulcanization reaction for 15 minutes at 15 MPa and 100° C. to obtain an organosilicon-based electromagnetic shielding composite material with high wave absorption in a wide frequency range.

[0052] The modified carbon fibers have a length of 0.1-5 mm, a diameter of 4-10 μm, and a resistivity of 1.0-1.6 Ω·cm;

[0053] The thickness of the organic silicon-based electromagnetic shielding composite material is 2 mm, and the content of the modified short-cut carbon fiber is 5 wt %.

[0054] Example 2

[0055] The preparation method of the electromagnetic shielding silicone rubber composite material with high wave absorption is different from that of Example 1 in that the anhydrous ethanol in step T2 of Example 1 is replaced by an ethanol aqueous solution with an equal weight fraction of 50% ethanol, and the remaining steps are the same as those of Example 1.

[0056] Example 3

[0057] The preparation method of the electromagnetic shielding silicone rubber composite material with high wave absorption is different from that of Example 1, in that the silane coupling agent RSi(OR')3 (R is octyl, R' is methyl) in step T2 of Example 1 is replaced by an equal weight portion of RSi(OR')3 (R is 3-(methacryloyloxy)propyl, R' is ethyl), and the remaining steps are the same as those in Example 1.

[0058] Example 4

[0059] The preparation method of the electromagnetic shielding silicone rubber composite material with high wave absorption is different from that of Example 2, in that the silane coupling agent RSi(OR')3 (R is octyl, R' is methyl) in step T2 of Example 2 is replaced by an equal weight portion of (R is 3-(methacryloyloxy)propyl, R' is ethyl), and the remaining steps are the same as those in Example 2.

[0060] Comparative Example

[0061] Comparative Example 1

[0062] The method for preparing the electromagnetic shielding silicone rubber composite material is different from that in Example 1 in that the modified chopped carbon fiber in Example 1 is not added, and the remaining steps are the same as those in Example 1.

[0063] Comparative Example 2

[0064] The preparation method of the electromagnetic shielding silicone rubber composite material is different from that of Example 1 in that 92 parts of liquid silicone rubber and 8 parts of modified carbon fiber prepared in step T2 are taken, and the remaining steps are the same as those of Example 1.

[0065] Performance testing

[0066] Test Example 1

[0067] The electromagnetic shielding performance of the highly absorbing electromagnetic shielding composite materials prepared in Examples 1-4 and Comparative Examples 1-2 was tested in the 8-12.4 GHz frequency band, 12-18 GHz frequency band, 18-26.5 GHz frequency band and 26.5-40 GHz frequency band, and the specific measurement results are shown in Table 1.

[0068] Table 1 Electromagnetic shielding effectiveness (8-12.4 GHz) of the electromagnetic shielding composite materials prepared in Examples 1-4 and Comparative Examples 1-2

[0069]

[0070] Reference Figure 1-4 Combined with the test results in Table 1, it can be seen that the composite material produced by the present invention has high electromagnetic shielding performance in the 8-12.4 GHz frequency band, with the absorption performance accounting for 80-88% of the total shielding performance. As the frequency increases, the shielding effectiveness of each sample is proportional to the frequency.

[0071] The shielding properties of the composite materials prepared from chopped carbon fibers modified with the same silane coupling agent in different environments are different; the shielding properties of the composite materials prepared from chopped carbon fibers modified with different silane coupling agents in the same modification environment are different; the shielding properties of the composite materials prepared from chopped carbon fibers modified with different silane coupling agents in different modification environments are different, among which Example 3 has the best shielding performance, reaching a maximum of 61dB.

[0072] In Comparative Example 6, due to the excessive amount of modified chopped carbon fibers, the silicone rubber composite material was difficult to be completely cured and could not maintain a smooth surface.

[0073] Table 2 Electromagnetic shielding effectiveness (12-18 GHz) of the electromagnetic shielding composite materials prepared in Examples 1-4 and Comparative Examples 1-2

[0074]

[0075] Reference Figure 1-4 Combined with the test results in Table 2, it can be seen that the composite material produced by the present invention has high electromagnetic shielding performance in the 12-18 GHz frequency band, with the absorption performance accounting for 82-93% of the total shielding performance. As the frequency increases, the shielding effectiveness of each sample is proportional to the frequency.

[0076] The shielding properties of the composite materials prepared from chopped carbon fibers modified with the same silane coupling agent in different environments are different; the shielding properties of the composite materials prepared from chopped carbon fibers modified with different silane coupling agents in the same modification environment are different; the shielding properties of the composite materials prepared from chopped carbon fibers modified with different silane coupling agents in different modification environments are different, among which Example 3 has the best shielding performance, reaching a maximum of 91dB.

[0077] In Comparative Example 6, due to the excessive amount of modified chopped carbon fibers, the silicone rubber composite material was difficult to be completely cured and could not maintain a smooth surface.

[0078] Table 3 Electromagnetic shielding effectiveness (18-26.5 GHz) of the electromagnetic shielding composite materials prepared in Examples 1-4 and Comparative Examples 1-2

[0079]

[0080] Reference Figure 1-4 Combined with the test results in Table 3, it can be seen that the composite materials produced by the present invention have high electromagnetic shielding performance in the 18-26.5 GHz frequency band, with the absorption performance accounting for 87%-94% of the total shielding performance. As the frequency increases, the shielding effectiveness of each sample is directly proportional to the frequency.

[0081] The overall shielding performance of each group of samples is similar. In the 18-26.5 GHz frequency band, changing the silane coupling agent and the modification environment has little effect on the overall shielding performance. The best shielding performance is Example 4, which reaches a maximum of 103 dB.

[0082] In Comparative Example 6, due to the excessive amount of modified chopped carbon fibers, the silicone rubber composite material was difficult to be completely cured and could not maintain a smooth surface.

[0083] Table 4 Electromagnetic shielding effectiveness (26.5-40 GHz) of the electromagnetic shielding composite materials prepared in Examples 1-4 and Comparative Examples 1-5

[0084]

[0085] Reference Figure 1-4 , and combined with the test results in Table 4, it can be seen that the composite material prepared by the present invention has high wave-absorbing electromagnetic shielding performance in the 26.5-40 GHz frequency band, and the wave-absorbing performance accounts for 88-95% of the total shielding performance.

[0086] Table 4 shows that the overall shielding performance of each group of samples is similar. In the 26.5-40 GHz frequency band, changing the silane coupling agent and the modification environment has little effect on the overall shielding performance. The best shielding performance is obtained in Example 1, reaching a maximum of 113 dB.

[0087] In Comparative Example 6, due to the excessive amount of modified chopped carbon fibers, the silicone rubber composite material was difficult to be completely cured and could not maintain a smooth surface.

[0088] Test Example 2

[0089] Seven experimental groups were set up, each of which prepared seven electromagnetic shielding silicone rubber composite materials. Experimental Group 1 was the electromagnetic shielding silicone rubber composite material prepared according to Example 1. Experimental Group 2 differed from Experimental Group 1 in that the modified chopped carbon fiber content was 0 wt %. Experimental Group 3 differed from Experimental Group 1 in that the modified chopped carbon fiber content was 0.5 wt %. Experimental Group 4 differed from Experimental Group 1 in that the modified chopped carbon fiber content was 1 wt %. Experimental Group 5 differed from Experimental Group 1 in that the modified chopped carbon fiber content was 2 wt %. Experimental Group 6 differed from Experimental Group 1 in that the modified chopped carbon fiber content was 3 wt %. Experimental Group 7 differed from Experimental Group 1 in that the modified chopped carbon fiber content was 6 wt %. The electromagnetic shielding silicone rubber composite materials of Experimental Groups 1-7 were tested for tensile strength and elongation at break according to GB / T 528-2009, Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber. The test results are shown in Table 5.

[0090] Table 5 Mechanical properties of magnetic shielding silicone rubber composite materials prepared in experimental groups 1-7

[0091]

[0092] Table 5 shows that the carbon fiber / silicone rubber composites produced by the present invention maintain excellent elongation at break and tensile strength at loadings ranging from 0.5 to 6 wt%. For each sample group, the elongation at break and tensile strength decrease with increasing loading. At a loading of 6 wt%, the elongation at break exceeds 300%, and the tensile strength is 4.6 MPa.

[0093] Reference Figure 1-4 As shown in Tables 1-4, in the 8-18 GHz frequency band, changing the silane coupling agent and the modification environment can change the overall shielding performance of the composite material, and as the frequency increases, the overall shielding performance of the composite material is proportional to the frequency; in the 18-40 GHz frequency band, the silane coupling agent and the modification environment have little effect on the composite material, and as the frequency increases, the overall shielding performance of the composite material remains stable.

[0094] The above are all preferred embodiments of the present invention, and are not intended to limit the scope of protection of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in the scope of protection of the present invention.

Claims

1. An electromagnetic shielding silicone rubber composite material with high wave absorption, characterized by: The invention comprises the following raw material components in parts by weight: 94-99.5 parts of liquid silicone rubber and 0.5-6 parts of modified chopped carbon fiber.

2. The broadband microwave-absorbing liquid silicone rubber composite material according to claim 1, characterized in that: The preparation steps of the modified chopped carbon fiber are as follows: 1) Take 2wt% sodium hydroxide solution, 2wt% nitric acid solution, and anhydrous ethanol respectively and wash the chopped carbon fibers in sequence; 2) mixing an ethanol aqueous solution and a silane coupling agent to obtain a mixed solution, and placing the chopped carbon fibers obtained in step 1) into the mixed solution for modification to obtain modified chopped carbon fibers; The modified chopped carbon fibers have a length of 0.1-5 mm and a diameter of 4-10 μm.

3. The electromagnetic shielding silicone rubber composite material with high wave absorption according to claim 2, characterized in that: The general formula of the silane coupling agent in step 2) is RSi(OR')3; The R group in the silane coupling agent includes any one of octyl, amino, epoxy, mercapto, 3-mercaptopropyl, 3-aminopropyl, aniline methyl, vinyl, 3-(methacryloyloxy)propyl, aminopropyl, and γ-glycidyloxypropyl; The R' group in the silane coupling agent includes any one of methyl, ethyl, propyl, β-methoxyethoxy, methoxy, and ethoxy.

4. The electromagnetic shielding silicone rubber composite material with high wave absorption according to claim 1, characterized in that The liquid silicone rubber is a two-component addition-type liquid rubber with a viscosity of 2000-4000 Pa·s.

5. The electromagnetic shielding silicone rubber composite material with high wave absorption according to claim 1, characterized in that: The electromagnetic shielding silicone rubber composite material has a density of less than 1.15g / cm³, a tensile strength at break greater than 4.2MPa, an elongation at break greater than 300%, an adjustable Shore A hardness in the range of 30-60 degrees, an electromagnetic shielding effectiveness in the 2-40GHz frequency domain greater than 50dB, and a wave absorption rate greater than 80%.

6. The method for preparing the electromagnetic shielding silicone rubber composite material with high wave absorption according to claim 1, comprising the following preparation steps: S1, respectively with modified chopped carbon fiber and liquid silicone rubber, the modified chopped carbon fiber is placed in the liquid silicone rubber and mechanically stirred to obtain a mixed rubber material; S2. Curing the mixed rubber material obtained in step S1 at room temperature or vulcanizing it at medium temperature on a flat vulcanizer to obtain an electromagnetic shielding silicone rubber composite material with high wave absorption.

7. The method for preparing the electromagnetic shielding silicone rubber composite material with high wave absorption according to claim 6, characterized in that: The mass fraction of ethanol in the ethanol aqueous solution in step S1 is 5-100%; The mass ratio of the ethanol aqueous solution, the silane coupling agent and the carbon fiber is 100:(0.5-15):

1.

8. The method for preparing the electromagnetic shielding silicone rubber composite material with high wave absorption according to claim 6, characterized in that: In step S3, the mass ratio of the modified chopped carbon fiber to the liquid silicone rubber is (0.5-6): (94-99.5).

9. The method for preparing the electromagnetic shielding silicone rubber composite material with high wave absorption according to claim 6, characterized in that: In step S4, the molding vulcanization temperature is 100-150° C., the vulcanization time is 5-20 min, and the pressure is 10-15 MPa.

Images