A solid-phase mixing method for preparing a vulcanized rubber material having an isolated network structure

Abstract

A solid-phase mixing preparation method of vulcanized rubber material with isolated network structure, characterized in that a rubber mixing process is completed by using an open mill or an internal mixer, then rubber mixing rubber powder is obtained by freezing and crushing, and then the rubber mixing rubber powder is coated with fillers by using a solid-phase mixing method, and after hot pressing and vulcanization, a vulcanized rubber material with good performance and isolated structure is obtained. In the preparation and implementation process of the preparation method, water or emulsion is not involved, the production process is simple, the cost is low, and the prepared rubber material can be applied to the fields of flexible conductor, sensor, electromagnetic shielding, thermal management, flame retardant, etc.

Description

Technical Field

[0001] This invention relates to a solid-phase mixing preparation method for vulcanized rubber materials with an isolated network structure, belonging to the field of polymer preparation. Background Technology

[0002] Liquid-phase mixing is a primary strategy for constructing an isolation network within a rubber matrix, and can be categorized into emulsion mixing and solution mixing. Emulsion mixing involves uniformly mixing fillers and rubber emulsions using methods such as ultrasound and stirring, followed by processes like flocculation, drying, and molding to obtain rubber materials with an isolation network structure. Compos. Sci. Technol., 2015, 116, 33-40; Chem. Eng. J. 2022, 435, 135118; Chem. Eng.J., 2018, 344, 184-193; J. Mater. Chem., 2012, 22, 10464-10468 Solution mixing refers to a method that uses a solvent to uniformly mix fillers and rubber, followed by filler self-assembly, drying, and other processes to obtain a rubber material with an isolated network structure. ACS Appl. Mater. Interfaces, 2020, 12, 9682−9692 Although liquid-phase mixing can construct an isolation network in a rubber matrix, this process has four drawbacks. (1) Long production cycle and high production cost. When using liquid-phase mixing to prepare rubber materials containing isolation networks, solvent removal is an essential step. Solvent removal not only prolongs the production cycle and increases production costs, but also causes certain environmental pollution. (2) Difficult to prepare vulcanized rubber materials. The necessary raw materials for rubber vulcanization (sulfur or vulcanization auxiliaries) are difficult to dissolve or disperse in water or other solvents, making liquid-phase mixing unsuitable for preparing vulcanized rubber. (3) Difficult to prepare highly filled rubber materials. When preparing highly filled rubber materials, it is impossible to ensure that the filler is uniformly dispersed in the latex or solution. Even if the filler is uniformly dispersed in the latex or solution through special processes, a large amount of filler coating the surface of the latex particles will seriously hinder the adhesion of rubber particles and the vulcanization process. (4) Difficult to prepare rubber materials with excellent mechanical properties. The difficulty in adding vulcanizing auxiliaries and ensuring uniform dispersion of fillers leads to poor mechanical properties in rubber materials prepared by liquid-phase mixing processes, making them unsuitable for practical applications. Achieving high-performance vulcanized rubber with an isolating network is a key issue that needs to be addressed in this field. Only by solving these problems can the prepared rubber products have practical application value. Based on the above analysis, developing a new solid-phase mixing process for vulcanized rubber with an isolating network is urgently needed. Summary of the Invention

[0003] The purpose of this invention is to provide a solid-phase mixing preparation method for vulcanized rubber materials with an isolated network structure, which addresses the shortcomings of existing technologies. The method is characterized by using an open mill or internal mixer to complete the rubber mixing process, then obtaining rubber compound powder through cryogenic pulverization, and then using a solid-phase mixing method to coat the surface of the rubber compound powder with fillers. After hot-pressing vulcanization, a vulcanized rubber material with good performance and an isolated structure is obtained.

[0004] The objective of this invention is achieved by the following technical measures, wherein the raw material fractions are all parts by weight unless otherwise specified.

[0005] A solid-phase mixing preparation method for a vulcanized rubber material with an isolated network structure includes the following steps:

[0006] (1) Preparation of rubber compound

[0007] Add 0.01-100 parts by weight of rubber, 0.01-110 parts by weight of filler, 0.01-10 parts by weight of sulfur, 0.01-10 parts by weight of zinc oxide, 0.01-10 parts by weight of stearic acid, 0.01-50 parts by weight of flame retardant, 0.01-10 parts by weight of antioxidant and 0.01-40 parts by weight of vulcanization accelerator to an internal mixer or two-roll mill, and mix at a temperature of 10-100 ℃ for 1-60 minutes to obtain rubber compound;

[0008] (2) Preparation of rubber compound powder

[0009] The above-mentioned rubber compound was added to a cryogenic pulverizer and cryogenically pulverized at a temperature of -200~0 ℃ for 0.5~60 minutes to obtain rubber compound powder.

[0010] (3) Preparation of filler-coated rubber compound powder

[0011] 0.01 to 100 parts by weight of the above-mentioned rubber compound powder and 0.01 to 100 parts by weight of filler are added to a cryogenic pulverizer, and the filler-coated rubber compound powder is obtained through a solid-phase mixing process.

[0012] (4) Preparation of vulcanized rubber materials with isolated network structure

[0013] The rubber compound powder coated with the above filler is subjected to hot pressing and vulcanization to obtain a vulcanized rubber material with an isolated network structure.

[0014] The rubber is at least one of the following: natural rubber, styrene-butadiene rubber, ethylene propylene diene monomer (EPDM) rubber, silicone rubber, butadiene rubber, isoprene rubber, nitrile rubber, chloroprene rubber, and butyl rubber.

[0015] The filler is at least one of carbon black, carbon nanotubes, silicon dioxide, graphene, graphite, transition metal carbon / nitride, iron(II,III) oxide, montmorillonite, calcium carbonate, boron nitride, kaolin, or mica powder; the flame retardant is at least one of magnesium hydroxide, aluminum hydroxide, antimony oxide, chlorophosphate, or melamine.

[0016] The antioxidant is any one of 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2,6-di-tert-butyl-p-cresol, or 2-(2-hydroxy-3,5-di-butyl-tert-phenyl)-5-chlorobenzotriazole; the vulcanization accelerator is at least one of thiol benzothiazole, benzothiazole disulfide, N-cyclohexyl-2-benzothiazole sulfenamide, tetramethylthiuram monosulfide, zinc dimethyl dithiocarbamate, diphenylguanidine, and ethylidene thiourea.

[0017] The solid-phase mixing process parameters are: temperature -200~10 ℃, time 0.5~60 minutes.

[0018] A solid-phase mixing preparation method for vulcanized rubber materials with an isolated network structure yields vulcanized rubber materials with an isolated network structure.

[0019] Vulcanized rubber materials with an isolated network structure are used in conductive materials, electromagnetic shielding materials, wave absorbing materials, thermal management materials, sensor materials, sealing materials, or tire materials.

[0020] Antioxidants, vulcanization accelerators, and flame retardants are known technologies in the art, provided that the addition of these additives does not adversely affect the achievement of the objectives of the present invention or the attainment of the excellent effects of the present invention.

[0021] Performance testing

[0022] The mechanical properties of vulcanized rubber materials with isolated network structures obtained by solid-phase mixing were tested using GB / T 528-2009. The tensile strength was measured to be 20~40 MPa, and the tear strength was measured to be 20~80 MPa using GB / T 529-2008. See Table 1 for details. Figure 1 It can be seen that there is an isolated network structure in the vulcanized rubber.

[0023] The present invention has the following advantages

[0024] 1. The solid-phase mixing method used in this invention constructs a network and other filler dispersion structure in the vulcanized rubber matrix to obtain a product with high conductivity and high mechanical properties. Compared with rubber materials prepared by the liquid phase method, it has the characteristics of short production cycle, good mechanical properties and high conductivity.

[0025] 2. The preparation process does not involve solutions or water and does not require drying, thus resulting in low energy consumption and low cost.

[0026] 3. The production process of this invention does not produce any waste gas or waste liquid, making it environmentally friendly. Attached Figure Description

[0027] Figure 1 This is a microstructure diagram of the vulcanized rubber with an isolated network structure obtained in Example 1. Detailed Implementation

[0028] The present invention will now be described in detail through embodiments. It should be noted that the following embodiments are only for further illustration of the present invention and should not be construed as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above description.

[0029] Example 1

[0030] 100 kg of natural rubber, 50 kg of carbon black, 4 kg of sulfur, 5 kg of zinc oxide, 2 kg of stearic acid, 3 kg of 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, and 1 kg of tetramethylthiuram monosulfide were added to a two-roll mill and mixed at 20 °C for 10 minutes to obtain a natural rubber compound. The obtained natural rubber compound was then added to a cryogenic pulverizer and cryogenically pulverized at -100 °C for 0.5 minutes to obtain a natural rubber compound powder. 100 kg of the obtained natural rubber compound powder and 10 kg of carbon nanotubes were then mixed using a solid-phase mixing process to obtain a natural rubber compound powder coated with carbon nanotubes at -100 °C for 0.5 minutes. Finally, a vulcanized natural rubber material with an isolated network structure was prepared by hot-press vulcanization molding at 150 °C for 10 minutes.

[0031] Example 2

[0032] 100 kg of styrene-butadiene rubber (SBR), 4 kg of carbon nanotubes, 3 kg of sulfur, 6 kg of zinc oxide, 4 kg of stearic acid, 50 kg of magnesium hydroxide, 3 kg of 2,6-di-tert-butyl-p-cresol, and 1 kg of N-cyclohexyl-2-benzothiazole sulfenamide were added to a two-roll mill and mixed at 10 °C for 5 minutes to obtain SBR compound. The obtained SBR compound was then added to a cryogenic pulverizer and cryogenically pulverized at -200 °C for 60 minutes to obtain SBR compound powder. 100 kg of the obtained SBR compound powder and 20 kg of graphite were then mixed using a solid-phase mixing process to obtain graphite-coated SBR compound powder at -200 °C for 60 minutes. Finally, a vulcanized SBR material with an isolated network structure was prepared by hot-press vulcanization molding at 170 °C for 8 minutes.

[0033] Example 3

[0034] 100 kg of silicone rubber, 12 kg of graphene, 4 kg of sulfur, 7 kg of zinc oxide, 5 kg of stearic acid, 3 kg of 2,6-di-tert-butyl-p-cresol, and 3 kg of N-cyclohexyl-2-benzothiazole sulfenamide were added to a two-roll mill and mixed at 15 °C for 15 minutes to obtain a silicone rubber compound. The resulting silicone rubber compound was then added to a cryogenic grinder and cryogenically ground at -170 °C for 3 minutes to obtain silicone rubber compound powder. 100 kg of the obtained silicone rubber compound powder and 19 kg of silica were then mixed using a solid-phase mixing process to obtain silica-coated silicone rubber compound powder at -170 °C for 6 minutes. Finally, a vulcanized styrene-butadiene rubber material with an isolated network structure was prepared by hot-press vulcanization molding at 190 °C for 11 minutes.

[0035] Example 4

[0036] 100 kg of nitrile rubber, 44 kg of calcium carbonate, 4 kg of sulfur, 7 kg of zinc oxide, 5 kg of stearic acid, 1.6 kg of 2-(2-hydroxy-3,5-dibutyltert-phenyl)-5-chlorobenzotriazole, and 2.3 kg of benzothiazole disulfide were added to a two-roll mill and mixed at 30 °C for 20 minutes to obtain nitrile rubber compound. The obtained nitrile rubber compound was then added to a cryogenic pulverizer and cryogenically pulverized at 0 °C for 2 minutes to obtain nitrile rubber compound powder. 100 kg of the obtained nitrile rubber compound powder and 33 kg of silica were then mixed using a solid-phase mixing process to obtain silica-coated nitrile rubber compound powder at 10 °C for 6 minutes. Finally, a vulcanized nitrile rubber material with an isolated network structure was prepared by hot-press vulcanization molding at 190 °C for 7 minutes.

[0037] Example 5

[0038] 100 kg of EPDM rubber, 14 kg of iron(III) oxide, 4 kg of sulfur, 3.2 kg of zinc oxide, 2.6 kg of stearic acid, 3.6 kg of 2-(2-hydroxy-3,5-dibutyltert-phenyl)-5-chlorobenzotriazole, and 4.3 kg of benzothiazole disulfide were added to a mixer and mixed at 20 °C for 15 minutes to obtain EPDM rubber compound. The obtained EPDM rubber compound was then added to a cryogenic pulverizer and cryogenically pulverized at -120 °C for 1 minute to obtain EPDM rubber compound powder. 100 kg of the obtained EPDM rubber compound powder and 6 kg of carbon nanotubes were then mixed using a solid-phase mixing process to obtain carbon nanotube-coated EPDM rubber compound powder at -120 °C for 7 minutes. Finally, EPDM rubber material with an isolated network structure was prepared by hot-press vulcanization molding at 150 °C. The temperature is ℃, and the vulcanization time is 9 minutes.

[0039] Example 6

[0040] 100 kg of butyl rubber, 19 kg of carbon black, 4 kg of sulfur, 3.4 kg of zinc oxide, 2.7 kg of stearic acid, 3.6 kg of 2-(2-hydroxy-3,5-dibutyltert-phenyl)-5-chlorobenzotriazole, and 4.3 kg of benzothiazole disulfide were added to a mixer and mixed at 22 °C for 15 minutes to obtain butyl rubber compound. The obtained butyl rubber compound was then added to a cryogenic pulverizer and cryogenically pulverized at -150 °C for 4 minutes to obtain butyl rubber compound powder. 100 kg of the obtained butyl rubber compound powder and 5 kg of carbon nanotubes were then mixed using a solid-phase mixing process to obtain carbon nanotube-coated butyl rubber compound powder at -120 °C for 4 minutes. Finally, a butyl rubber material with an isolated network structure was prepared by hot-press vulcanization molding at 170 °C for 3 minutes.

[0041] Comparison Example 1

[0042] Vulcanized rubber with an isolated network structure prepared by liquid-phase mixing method:

[0043] 166.7 kg of natural latex, 1000 kg of water, 50 kg of carbon black, 10 kg of carbon nanotubes, 4 kg of sulfur, 5 kg of zinc oxide, 2 kg of stearic acid, 3 kg of 2-(2'-hydroxy-5'-methylphenyl)benzotriazole and 1 kg of tetramethylthiuram monosulfide were added to a reaction vessel and mixed evenly. The mixture was dried at 80°C for 10 hours to obtain a masterbatch, which was then kneaded in a two-roll mill at 20°C for 10 minutes to obtain a natural rubber compound. A vulcanized natural rubber material with an isolated network structure was prepared by hot pressing vulcanization molding at 150°C for 10 minutes.

[0044] Compared with Comparative Example 1, Example 1 does not involve a drying process, has a short production cycle, excellent mechanical properties, tensile strength is 2.8 times that of Comparative Example 1, and good electrical conductivity.

[0045] Comparison Example 2

[0046] Vulcanized natural rubber materials without a separating network structure prepared using a conventional open mill:

[0047] 100 kg of natural latex, 50 kg of carbon black, 10 kg of carbon nanotubes, 4 kg of sulfur, 5 kg of zinc oxide, 2 kg of stearic acid, 3 kg of 2-(2'-hydroxy-5'-methylphenyl)benzotriazole and 1 kg of tetramethylthiuram monosulfide were mixed in a two-roll mill at 20 °C for 10 minutes to obtain a natural rubber compound. A vulcanized natural rubber material without an isolation network structure was prepared by hot-pressing vulcanization molding at 150 °C for 10 minutes.

[0048] Compared with Comparative Example 2, the biggest advantage of Example 1 is its good conductivity, which is 6 orders of magnitude higher than that of Comparative Example 2.

[0049] Table 1. Comparison of natural rubber prepared by the liquid phase method and the natural rubber composite material prepared by this invention*

[0050] Maximum torque Nm Tensile strength (MPa) Tensile modulus (MPa) Elongation at break % Tear strength N / mm Conductivity S / m Comparison Example 1 2.4 10 5.6 231 22 0.5 Comparison Example 2 2.3 25 9.7 550 40 <![CDATA[5.5×10 -6 ]]> Example 1 2.3 28 9.8 612 44 7.2

[0051] *The tensile properties of Comparative Example 1, Comparative Example 2 and Example 1 were tested according to GB / T 528-2009; the tear properties of Comparative Example 1, Comparative Example 2 and Example 1 were tested according to GB / T 529-2008; and the electrical conductivity of Comparative Example 1, Comparative Example 2 and Example 1 was tested according to GB / T 2439-2001.

[0052] The performance comparison of Example 1 and the comparative example confirms that the solid-phase mixing method involved in this invention is a key step in improving the mechanical and electrical properties of vulcanized rubber materials.

Claims

1. A solid-phase mixing preparation method for a vulcanized rubber material with an isolated network structure, characterized in that... The method includes the following steps: (1) Preparation of rubber compound Add 0.01~100 parts by weight of rubber, 0.01~110 parts by weight of filler, 0.01~10 parts by weight of sulfur, 0.01~10 parts by weight of zinc oxide, 0.01~10 parts by weight of stearic acid, 0.01~50 parts by weight of flame retardant, 0.01~10 parts by weight of antioxidant and 0.01~40 parts by weight of vulcanization accelerator to an internal mixer or a two-roll mill, and mix at a temperature of 10~100℃ for 1~60 minutes to obtain rubber compound; (2) Preparation of rubber compound powder The above-mentioned rubber compound was added to a cryogenic pulverizer and cryogenically pulverized at a temperature of -200~0℃ for 0.5~60 minutes to obtain rubber compound powder. (3) Preparation of filler-coated rubber compound powder 0.01-100 parts by weight of the above-mentioned rubber compound powder and 0.01-100 parts by weight of filler are added to a cryogenic pulverizer, and the filler-coated rubber compound powder is obtained through a solid-phase mixing process; the filler is at least one of carbon black, carbon nanotubes, silicon dioxide, graphene, graphite, transition metal carbon / nitride, iron tetroxide, montmorillonite, calcium carbonate, boron nitride, kaolin or mica powder; (4) Preparation of vulcanized rubber materials with isolated network structure The rubber compound powder coated with the above filler is subjected to hot pressing and vulcanization to obtain a vulcanized rubber material with an isolated network structure.

2. The solid-phase mixing preparation method according to claim 1, characterized in that, In step (3), the solid-phase mixing process parameters are a temperature of -200~10 ℃ and a time of 0.5~60 minutes.

3. The application of vulcanized rubber materials with an isolated network structure obtained by the solid-phase mixing preparation method according to any one of claims 1-2 in the fields of conductive materials, electromagnetic shielding materials, wave absorbing materials, thermal management materials, sensor materials, sealing materials, or tire materials.

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