Conductive halogenated butyl rubber composite material and preparation method thereof

Abstract

The invention belongs to the technical field of conductive rubber composite materials, and particularly relates to a conductive halogenated butyl rubber composite material and a preparation method thereof.The method comprises the steps that halogenated butyl rubber and an ionic cross-linking agent are mixed and react to obtain halogenated butyl rubber ionomer, the halogenated butyl rubber ionomer and a covalent cross-linking agent are mixed and react to obtain the conductive halogenated butyl rubber composite material. The preparation method comprises the following steps: reacting to obtain a halogenated butyl rubber polymer, soaking the halogenated butyl rubber polymer in a good solvent until swelling equilibrium, and then transferring the halogenated butyl rubber polymer into a conductive filler dispersion liquid for dipping to obtain the conductive halogenated butyl rubber composite material. The conductive filler is introduced into the surface of the halogenated butyl rubber polymer with a covalent-ionic hybrid cross-linked structure by using a swelling driven penetration method, so that a firm conductive network can be constructed on the surface layer of the rubber, and the influence of viscoelasticity of a rubber molecular chain on the deformation of the conductive network can be reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of conductive rubber composite materials, and in particular relates to a conductive halogenated butyl rubber composite material and a preparation method thereof. Background Art

[0002] In recent years, flexible wearable strain sensors have shown great application prospects in the fields of health monitoring, medical diagnosis, electronic skin, human-computer interaction, etc. The working principle of strain sensors is to convert external mechanical stimuli into electrical signals. In order to achieve a wide monitoring range of strain sensors, highly elastic polymer materials are usually selected as matrix materials. Halogenated butyl rubber has high mechanical strength, low air permeability, aging resistance, high shock absorption, low toxicity and skin-friendly properties, and is considered to be one of the ideal matrix materials for flexible strain sensors. However, rubber is usually an insulating material and cannot convert external mechanical stimuli into electrical signals. Therefore, it is usually necessary to introduce various conductive fillers to convert insulating rubber into conductors to give it electromechanical conversion capabilities. At present, the method for preparing conductive rubber composites is mainly based on physical blending, and a uniform conductive filler network is constructed in the rubber matrix through processes such as surface modification. However, due to the viscoelastic properties of the rubber molecular chain, the destruction and reconstruction of the conductive network will be affected during dynamic stretching, thereby causing electrical hysteresis and affecting the sensing performance of the sensor.

[0003] In order to reduce the influence of the viscoelasticity of the rubber molecular chain on the deformation process of the conductive network, on the one hand, the cross-linked network structure of the rubber can be regulated. For example, increasing the cross-linking density can enhance the binding effect on the rubber molecular chain, thereby reducing the viscosity loss; on the other hand, a conductive layer can be constructed on the rubber surface through processes such as spin coating, screen printing, and self-assembly, thereby reducing the contact area between the conductive filler and the rubber molecular chain. However, due to the imbalance in the modulus matching between the rigid conductive filler and the soft rubber matrix, it is very difficult to construct a firm conductive layer on the rubber surface. To solve this problem, a method for preparing a conductive rubber composite material using a swelling-driven infiltration method was developed. In this method, the rubber material is first swollen in a good solvent, and then immersed in a conductive filler dispersion to allow the conductive filler to diffuse and penetrate into the rubber surface. The rubber is then taken out and dried. As the solvent evaporates, the rubber volume gradually shrinks and fixes the conductive filler on the surface to form a conductive layer. The invention patent with application number 201710637577.7 adopts the swelling-driven infiltration method to prepare a conductive carbon nanotube / silicone rubber composite material. Since the carbon nanotubes are partially embedded in the silicone rubber matrix, the firmness of the conductive network is undoubtedly enhanced. However, the swelling degree of the rubber is an important factor affecting the construction of the conductive layer network, and the cross-linking density determines the swelling degree of the rubber. As a result, the prior art has the following contradiction: although the rubber with a lower cross-linking density has a higher swelling rate in the solvent and is more conducive to the diffusion of the conductive filler, it will also lead to an increase in the viscosity loss of the rubber material, resulting in more serious electrical hysteresis and sensing instability. Summary of the invention

[0004] The purpose of the present invention is to provide a conductive halogenated butyl rubber composite material and a preparation method thereof, which can construct a firm conductive network on the rubber surface and reduce the influence of the viscoelasticity of the rubber molecular chain on the deformation of the conductive network.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] In a first aspect, the present invention provides a method for preparing a conductive halogenated butyl rubber composite material, the preparation method comprising:

[0007] The halogenated butyl rubber is mixed with an ionic crosslinking agent to react to obtain a halogenated butyl rubber ionomer having an ionic crosslinking network;

[0008] The halogenated butyl rubber ionomer is mixed with a covalent crosslinking agent to react and obtain a halogenated butyl rubber polymer having a covalent-ionic hybrid crosslinking structure;

[0009] The halogenated butyl rubber polymer is firstly immersed in a good solvent to reach swelling equilibrium, then transferred to a conductive filler dispersion for immersion, and dried to obtain a conductive halogenated butyl rubber composite material.

[0010] The ionic crosslinking agent is at least one of imidazole, 1-butylimidazole, 1-(3-aminopropyl)imidazole, 1-(2-hydroxyethyl)imidazole, 1-ethylimidazole, 1-vinylimidazole, 2-phenylimidazole, 1,2-dimethylimidazole, pyridine, 4-methylpyridine, 4-tert-butylpyridine, 4-(dimethylamino)pyridine, and 4-(dibutylamino)pyridine.

[0011] The covalent crosslinking agent is at least one of zinc oxide, sulfur, diisophenyl peroxide, N,N'-m-phenylene bismaleimide, phenolic resin and zinc chloride.

[0012] The good solvent is at least one of dichloromethane, chloroform, dimethylformamide, dimethylacetamide, tetrahydrofuran, toluene, xylene and cyclohexane.

[0013] The conductive filler is at least one of carbon black, carbon nanotubes, graphene, reduced graphene oxide, graphite, carbon fiber, titanium carbide, and nanosilver.

[0014] The concentration of the conductive filler dispersion is 0.1-10%wt.

[0015] The weight ratio of the halogenated butyl rubber to the ionic crosslinking agent and the covalent crosslinking agent is 100:0.05-8:0.05-10.

[0016] In a second aspect, the present invention provides a conductive halogenated butyl rubber composite material, which is prepared by the aforementioned preparation method.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The present invention discloses a method for preparing a conductive halogenated butyl rubber composite material, which comprises the following steps: firstly mixing the halogenated butyl rubber with an ionic crosslinking agent to react and obtain a halogenated butyl rubber ionomer having an ionic crosslinking network; then mixing the halogenated butyl rubber ionomer with a covalent crosslinking agent to react and obtain a halogenated butyl rubber polymer having a covalent-ionic hybrid crosslinking structure; then firstly placing the halogenated butyl rubber polymer in a good solvent and soaking it until swelling equilibrium is reached, and then transferring it to a conductive filler dispersion for soaking, to obtain a conductive halogenated butyl rubber composite material. The halogenated butyl rubber polymer obtained by the method has a covalent-ionic hybrid crosslinking structure, wherein the ionic crosslinking network is dynamically reversible, and the ionic crosslinking network undergoes reverse dissociation during the swelling process, thereby increasing the swelling rate, promoting the conductive filler to immerse into the rubber surface to form a conductive network, and drying the sample after the conductive network is formed. During this process, the ionic crosslinking network will be re-formed, and together with the covalent crosslinking network, the high crosslinking density of the conductive halogenated butyl rubber composite material is ensured, thereby more effectively reducing the viscosity loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of the reaction between the ionic crosslinking agent of Example 1 and brominated butyl rubber.

[0020] Figure 2 Schematic diagram of the covalent-ionic hybrid crosslinking structure of the brominated butyl rubber polymer of Example 1.

[0021] Figure 3 The cross-sectional scanning electron microscope images of the composite materials obtained in Example 1 and Comparative Example 1 are shown.

[0022] Figure 4 The loss factor-temperature curves of Example 1 and Comparative Example 1 are shown. DETAILED DESCRIPTION

[0023] The present invention is further described in detail below in conjunction with specific implementations and drawings.

[0024] A method for preparing a conductive halogenated butyl rubber composite material, the preparation method comprising:

[0025] The halogenated butyl rubber is mixed with an ionic crosslinking agent to react to obtain a halogenated butyl rubber ionomer having an ionic crosslinking network;

[0026] The halogenated butyl rubber ionomer is mixed with a covalent crosslinking agent to react and obtain a halogenated butyl rubber polymer having a covalent-ionic hybrid crosslinking structure;

[0027] The halogenated butyl rubber polymer is firstly immersed in a good solvent to reach swelling equilibrium, then transferred to a conductive filler dispersion for immersion, and dried to obtain a conductive halogenated butyl rubber composite material.

[0028] The ionic crosslinking agent is at least one of imidazole, 1-butylimidazole, 1-(3-aminopropyl)imidazole, 1-(2-hydroxyethyl)imidazole, 1-ethylimidazole, 1-vinylimidazole, 2-phenylimidazole, 1,2-dimethylimidazole, pyridine, 4-methylpyridine, 4-tert-butylpyridine, 4-(dimethylamino)pyridine, and 4-(dibutylamino)pyridine.

[0029] The covalent crosslinking agent is at least one of zinc oxide, sulfur, diisophenylene peroxide, N,N'-m-phenylene bismaleimide, phenolic resin and zinc chloride.

[0030] The good solvent is at least one of dichloromethane, chloroform, dimethylformamide, dimethylacetamide, tetrahydrofuran, toluene, xylene and cyclohexane.

[0031] The conductive filler is at least one of carbon black, carbon nanotubes, graphene, reduced graphene oxide, graphite, carbon fiber, titanium carbide, and nanosilver.

[0032] The concentration of the conductive filler dispersion is 0.1-10%wt.

[0033] The weight ratio of the halogenated butyl rubber to the ionic crosslinking agent and the covalent crosslinking agent is 100:0.05-8:0.05-10.

[0034] A conductive halogenated butyl rubber composite material is prepared by the above-mentioned preparation method.

[0035] The principle of the present invention is described as follows:

[0036] The method of the present invention first constructs a covalent-ionic hybrid cross-linked network in a halogenated butyl rubber matrix, and then introduces a conductive filler into the rubber surface by a swelling-driven infiltration method to prepare a conductive halogenated butyl rubber composite material, thereby solving the problem of large hysteresis loss and weak surface conductive layer of halogenated butyl rubber. The method of the present invention is simple to operate, has good controllability, and is easy to scale up for industrial production, and can expand the application of halogenated butyl rubber in the fields of flexible electronic devices and the like.

[0037] Ionic crosslinking mechanism: At high temperatures, the allyl halogen groups on the halogenated butyl rubber molecular chain isomerize from the external conformation to the internal conformation. Since the internal allyl halogen atoms have higher reactivity, they can undergo alkylation reaction with ionic crosslinking agents containing imidazole or pyridine rings at 80-160°C, thereby converting the halogenated butyl rubber into ionomers. Since imidazole or pyridinium cations aggregate to form ion clusters, an ionic crosslinking network is formed in the ionomer.

[0038] In the ion cross-linked network, the ion clusters formed by imidazole or pyridinium cations are dynamically reversible and will dissociate in a good solvent, increasing the swelling rate. The higher the swelling rate, the easier it is for the conductive filler to be immersed, and the thicker the conductive layer formed in the end. After the conductive filler is impregnated, the volume of the rubber shrinks during the drying process, thereby fixing the conductive filler on the surface of the rubber. The more the conductive filler is embedded in the rubber, the stronger the conductive layer. After the good solvent evaporates, the ion cross-linked network will be re-formed to ensure the high cross-linking density of the composite material, thereby more effectively reducing the viscosity loss. Since the ion cross-linking agent needs to undergo an alkylation reaction with the allyl halogen atoms in the halogenated butyl rubber to form an ion cross-linked network, the amount of the ion cross-linking agent added can be determined according to the amount of reaction with the halogen atoms. If the amount of the ion cross-linking agent added is too high, it will not only cause waste, but also easily precipitate and dissolve into the solvent during the swelling process, causing environmental pollution.

[0039] Covalent crosslinking mechanism: Halogenated butyl rubber molecular chains contain double bonds. The added covalent crosslinking agent reacts with the double bonds or the α hydrogen on the double bonds to form a carbon-carbon or carbon-sulfur covalent crosslinking network. This covalent crosslinking process will not destroy the formation of the ionic crosslinking network.

[0040] The covalent cross-linking network can only swell in a good solvent, but not dissociate, so the covalent cross-linking network can give the halogenated butyl rubber swelling stability. The amount of covalent cross-linking agent added should be neither too high nor too low. If it is too high, the swelling degree of the halogenated butyl rubber will be very limited, which is not conducive to the infiltration of the conductive filler. If it is too low, the covalent cross-linking density of the halogenated butyl rubber will be too low, and the rubber viscosity loss will increase. Taking the above into consideration, the weight ratio of halogenated butyl rubber, ionic cross-linking agent, and covalent cross-linking agent is controlled at 100:0.05-8:0.05-10, so that the covalent cross-linking part is maintained in an appropriate range, ensuring that a firm conductive network can be built on the rubber surface, and the influence of rubber viscosity loss on the deformation of the conductive network is reduced as much as possible.

[0041] Embodiment 1:

[0042] A method for preparing a conductive halogenated butyl rubber composite material is carried out in the following steps:

[0043] S1. Quantitatively weigh 40 g of brominated butyl rubber and put it into an internal mixer for plasticization at 60° C. for 3 min. Add 0.84 g of an ionic crosslinking agent and mix for 1 min. The ionic crosslinking agent is 1-butyl imidazole. Raise the temperature of the internal mixer to 100° C. and mix for 10 min. The brominated butyl rubber is isomerized by heat, and the ionic crosslinking agent and bromine element undergo substitution reaction to obtain a brominated butyl rubber ionomer having an ionic crosslinking network. The ionic crosslinking process is as follows: Figure 1 As shown:

[0044] S2, mixing the brominated butyl rubber ionomer and 0.8 g of a covalent crosslinking agent on a two-roll mill, wherein the covalent crosslinking agent is zinc oxide; vulcanizing and molding at 160° C. to obtain a brominated butyl rubber polymer having a covalent-ionic hybrid crosslinking structure; the covalent-ionic hybrid crosslinking structure is as follows Figure 2 As shown:

[0045] S3, soaking the brominated butyl rubber polymer in a good solvent for 6 hours, wherein the good solvent is tetrahydrofuran;

[0046] S4, transferring the brominated butyl rubber polymer to a conductive filler dispersion having a concentration of 0.1%wt and immersing the dispersion for 12 hours, wherein the conductive filler dispersion is a carbon nanotube dispersion; taking out and drying to obtain a conductive brominated butyl rubber composite material.

[0047] Embodiment 2:

[0048] A method for preparing a conductive halogenated butyl rubber composite material is carried out in the following steps:

[0049] S1. Quantitatively weigh 30 g of chlorobutyl rubber and put it into an internal mixer for plasticization at 50° C. for 13 min. Add 0.1 g of an ionic crosslinking agent and mix for 2 min. Raise the temperature of the internal mixer to 120° C. and mix for 15 min to obtain a chlorobutyl rubber ionomer having an ionic crosslinking network. The ionic crosslinking agent includes 0.4 g of imidazole and 0.6 g of 1-vinylimidazole.

[0050] S2, mixing chlorinated butyl rubber ionomer, 1.2g covalent crosslinking agent and 3.3g auxiliary agent on a two-roll mill, and vulcanizing and molding at 160°C to obtain chlorinated butyl rubber polymer with a covalent-ionic hybrid crosslinking structure; the covalent crosslinking agent includes 1.2g sulfur; the auxiliary agent includes 1.5g zinc oxide (zinc oxide is a covalent crosslinking agent when used alone, and zinc oxide acts as an active agent rather than a covalent crosslinking agent when zinc oxide and sulfur are used together), 1g stearic acid, and 0.8g accelerator CZ;

[0051] S3, soaking the chlorinated butyl rubber polymer in a good solvent for 3 hours; the good solvent is dichloromethane;

[0052] S4, transferring the chlorinated butyl rubber polymer to a conductive filler dispersion having a concentration of 0.5%wt and immersing the polymer for 12 hours, wherein the conductive filler dispersion is a carbon black dispersion; taking the polymer out and drying the dispersion to obtain a conductive chlorinated butyl rubber composite material.

[0053] Embodiment 3:

[0054] A method for preparing a conductive halogenated butyl rubber composite material is carried out in the following steps:

[0055] S1. Quantitatively weigh 40 g of brominated butyl rubber and put it into an internal mixer for plasticization at 70° C. for 2 min. Add 1.13 g of an ionic crosslinking agent and mix for 2 min. Raise the temperature of the internal mixer to 130° C. and mix for 8 min to obtain a brominated butyl rubber ionomer having an ionic crosslinking network. The ionic crosslinking agent is 1-(3-aminopropyl)imidazole.

[0056] S2, mixing the brominated butyl rubber ionomer and 0.4 g of a covalent crosslinking agent on a two-roll mill, and vulcanizing and molding at 170° C. to obtain a brominated butyl rubber polymer having a covalent-ionic hybrid crosslinking structure; the covalent crosslinking agent is diisopropyl peroxide;

[0057] S3, soaking the brominated butyl rubber polymer in a good solvent for 1 hour; the good solvent is dimethylformamide;

[0058] S4, transferring the brominated butyl rubber polymer to a conductive filler dispersion having a concentration of 1%wt and immersing the polymer for 6 hours, wherein the conductive filler dispersion is a graphene dispersion; taking the polymer out and drying the dispersion to obtain a conductive brominated butyl rubber composite material.

[0059] Embodiment 4:

[0060] A method for preparing a conductive halogenated butyl rubber composite material is carried out in the following steps:

[0061] S1. Quantitatively weigh 60 g of brominated butyl rubber and put it into an internal mixer for plasticization at 70° C. for 2 min. Add 1.51 g of an ionic crosslinking agent and mix for 2 min. Raise the temperature of the internal mixer to 130° C. and mix for 12 min to obtain a brominated butyl rubber ionomer having an ionic crosslinking network. The ionic crosslinking agent is 1-(2-hydroxyethyl)imidazole.

[0062] S2, mixing the brominated butyl rubber ionomer and 1.5 g of a covalent crosslinking agent on a two-roll mill, and vulcanizing and molding at 165° C. to obtain a brominated butyl rubber polymer having a covalent-ionic hybrid crosslinking structure; the covalent crosslinking agent is N,N'-m-phenylene bismaleimide;

[0063] S3, soaking the brominated butyl rubber polymer in a good solvent for 8 hours; the good solvent is xylene;

[0064] S4, transferring the brominated butyl rubber polymer to a conductive filler dispersion having a concentration of 0.7% wt and immersing it for 5 hours, wherein the conductive filler dispersion is a reduced graphene oxide dispersion; taking it out and drying it to obtain a conductive brominated butyl rubber composite material.

[0065] Embodiment 5:

[0066] A method for preparing a conductive halogenated butyl rubber composite material is carried out in the following steps:

[0067] S1. 40 g of chlorobutyl rubber was weighed quantitatively and put into an internal mixer for plasticization at 50° C. for 2 min. 1.51 g of an ionic crosslinking agent was added and mixed for 2 min. The temperature of the internal mixer was increased to 150° C. and mixed for 15 min to obtain a chlorobutyl rubber ionomer having an ionic crosslinking network. The ionic crosslinking agent was 1.3 g of 1-ethylimidazole and 0.21 g of 4-(dibutylamino)pyridine.

[0068] S2, mixing the chlorinated butyl rubber ionomer and 1.15 g of a covalent crosslinking agent on a two-roll mill, and vulcanizing and molding at 170° C. to obtain a chlorinated butyl rubber polymer having a covalent-ionic hybrid crosslinking structure; the covalent crosslinking agent is N,N'-m-phenylene bismaleimide;

[0069] S3, soaking the chlorinated butyl rubber polymer in a good solvent for 5 hours; the good solvent is tetrahydrofuran;

[0070] S4, transferring the chlorinated butyl rubber polymer to a conductive filler dispersion having a concentration of 1%wt and immersing the polymer for 3 hours, wherein the conductive filler dispersion is a graphite dispersion; taking the polymer out and drying the dispersion to obtain a conductive chlorinated butyl rubber composite material.

[0071] Embodiment 6:

[0072] A method for preparing a conductive halogenated butyl rubber composite material is carried out in the following steps:

[0073] S1. Quantitatively weigh 45 g of brominated butyl rubber and put it into an internal mixer for plasticization at 50° C. for 2 min. Add 0.95 g of an ionic crosslinking agent and mix for 3 min. Raise the temperature of the internal mixer to 140° C. and mix for 12 min to obtain a brominated butyl rubber ionomer having an ionic crosslinking network. The ionic crosslinking agent is 4-tert-butylpyridine.

[0074] S2, mixing the brominated butyl rubber ionomer and 3.25 g of a covalent crosslinking agent on a two-roll mill, and vulcanizing and molding at 155° C. to obtain a brominated butyl rubber polymer having a covalent-ionic hybrid crosslinking structure; the covalent crosslinking agent is 2.75 g of a phenolic resin and 1.5 g of zinc chloride;

[0075] S3, soaking the brominated butyl rubber polymer in a good solvent for 5 hours; the good solvent is chloroform;

[0076] S4, transferring the brominated butyl rubber polymer to a conductive filler dispersion having a concentration of 1.5%wt and immersing the polymer for 2 hours, wherein the conductive filler dispersion is a graphite dispersion; taking the polymer out and drying the dispersion to obtain a conductive brominated butyl rubber composite material.

[0077] Embodiment 7:

[0078] A method for preparing a conductive halogenated butyl rubber composite material is carried out in the following steps:

[0079] S1. 50 g of brominated butyl rubber was weighed quantitatively and put into an internal mixer for plasticization at 75° C. for 1 min. 1.62 g of an ionic crosslinking agent was added and mixed for 1 min. The temperature of the internal mixer was increased to 165° C. and mixed for 14 min to obtain a brominated butyl rubber ionomer having an ionic crosslinking network. The ionic crosslinking agent was 2-phenylimidazole.

[0080] S2, mixing the brominated butyl rubber ionomer, 0.88 g of a covalent crosslinking agent, and 0.75 g of an auxiliary agent on a two-roll mill, and vulcanizing and molding at 140° C. to obtain a brominated butyl rubber polymer having a covalent-ionic hybrid crosslinking structure; the covalent crosslinking agent is zinc oxide; and the auxiliary agent is antioxidant 4020;

[0081] S3, soaking the brominated butyl rubber polymer in a good solvent for 2.5 hours; the good solvent is toluene;

[0082] S4, transferring the brominated butyl rubber polymer to a conductive filler dispersion having a concentration of 5%wt and immersing the polymer for 5 hours, wherein the conductive filler dispersion is a carbon fiber dispersion; taking the polymer out and drying the dispersion to obtain a conductive brominated butyl rubber composite material.

[0083] Embodiment 8:

[0084] A method for preparing a conductive halogenated butyl rubber composite material is carried out in the following steps:

[0085] S1. Quantitatively weigh 75 g of brominated butyl rubber and put it into an internal mixer and plasticize it at 85° C. for 2.5 min. Add 1.62 g of an ionic crosslinking agent and mix it for 1 min. Raise the temperature of the internal mixer to 160° C. and mix it for 12 min to obtain a brominated butyl rubber ionomer having an ionic crosslinking network. The ionic crosslinking agent is 1.4 g of 1,2-dimethylimidazole and 0.22 g of 4-(dimethylamino)pyridine.

[0086] S2, mixing the brominated butyl rubber ionomer and 0.6g of a covalent crosslinking agent on a two-roll mill, and vulcanizing and molding at 130°C to obtain a brominated butyl rubber polymer having a covalent-ionic hybrid crosslinking structure; the covalent crosslinking agent is 0.5g of zinc chloride and 0.1g of diisopropyl peroxide;

[0087] S3, soaking the brominated butyl rubber polymer in a good solvent for 4 hours; the good solvent is cyclohexane;

[0088] S4, transferring the brominated butyl rubber polymer to a conductive filler dispersion having a concentration of 1.5%wt and immersing the dispersion for 5 hours, wherein the conductive filler dispersion is a titanium carbide dispersion; taking out and drying to obtain a conductive brominated butyl rubber composite material.

[0089] Embodiment 9:

[0090] A method for preparing a conductive halogenated butyl rubber composite material is carried out in the following steps:

[0091] S1. 50 g of brominated butyl rubber was weighed quantitatively and put into an internal mixer for plasticization at 55° C. for 2 min; 0.8 g of an ionic crosslinking agent was added and mixed for 1 min, and the temperature of the internal mixer was increased to 130° C. and mixed for 8 min to obtain a brominated butyl rubber ionomer having an ionic crosslinking network; the ionic crosslinking agent included 0.7 g of pyridine and 0.1 g of 4-methylpyridine;

[0092] S2, mixing the brominated butyl rubber ionomer and 0.1 g of a covalent crosslinking agent on a two-roll mill, and vulcanizing and molding at 170° C. to obtain a brominated butyl rubber polymer having a covalent-ionic hybrid crosslinking structure; the covalent crosslinking agent is diisopropyl peroxide;

[0093] S3, soaking the brominated butyl rubber polymer in a good solvent for 2 hours; the good solvent is tetrahydrofuran;

[0094] S4, transferring the brominated butyl rubber polymer to a conductive filler dispersion having a concentration of 10% wt and immersing the polymer for 5 hours, wherein the conductive filler dispersion is a nanosilver dispersion; taking the polymer out and drying the nanosilver dispersion to obtain a conductive brominated butyl rubber composite material.

[0095] Comparative Example 1:

[0096] S1. Quantitatively weigh 40 g of brominated butyl rubber and 1.6 g of a covalent crosslinking agent, mix them evenly on a two-roll mill, and vulcanize and mold them at 160° C. to obtain covalently crosslinked brominated butyl rubber; the covalent crosslinking agent is zinc oxide;

[0097] S2, soaking the covalently cross-linked brominated butyl rubber in a good solvent for 6 hours, wherein the good solvent is tetrahydrofuran;

[0098] S3, transferring the covalently cross-linked brominated butyl rubber to a 0.1%wt conductive filler dispersion and immersing it for 12 hours, wherein the conductive filler dispersion is a carbon nanotube dispersion; taking it out and drying it to obtain a conductive brominated butyl rubber composite material.

[0099] Comparative Example 2:

[0100] S1. Quantitatively weigh 30g of chlorobutyl rubber, 1.2g of covalent crosslinking agent and 3.3g of auxiliary agent, mix them evenly on a two-roll mill, and vulcanize and mold them at 160°C to obtain a chlorobutyl rubber polymer with covalent crosslinking; the covalent crosslinking agent is sulfur; the auxiliary agent is 1.5g of active agent zinc oxide, 1g of stearic acid, and 0.8g of accelerator CZ;

[0101] S2, soaking the chlorobutyl rubber polymer in a good solvent for 3 hours; the good solvent is dichloromethane;

[0102] S3, transferring the chlorinated butyl rubber polymer to a conductive filler dispersion with a concentration of 0.5%wt and immersing it for 12 hours, wherein the conductive filler dispersion is a carbon black dispersion; taking it out and drying it to obtain a conductive chlorinated butyl rubber composite material.

[0103] Performance Verification:

[0104] (1) The composite materials prepared in Example 1 and Comparative Example 1 were fractured in liquid nitrogen and then observed by scanning electron microscopy. The results are as follows: Figure 3 The thickness of the conductive layer of Example 1 and Comparative Example 1 is 715nm and 565nm respectively. By comparison, it can be seen that the surface of the composite material of Example 1 has a thicker conductive layer. This is because the brominated butyl rubber polymer with a covalent-ionic hybrid cross-linking structure has a higher swelling ratio, which can promote the infiltration of more carbon nanotubes, thereby increasing the thickness of the conductive layer.

[0105] (2) Dynamic mechanical properties of the composite materials prepared in Example 1 and Comparative Example 1 were tested, and the loss factor-temperature curves obtained were as follows: Figure 4 As shown. Figure 4 It can be seen that compared with Comparative Example 1, the composite material of Example 1 has a significantly lower loss factor at -30°C to 50°C, which indicates that the covalent-ionic hybrid cross-linking structure has a stronger binding effect on the brominated butyl rubber molecular chain, thereby reducing the viscous loss.

[0106] (3) Conductivity and 25° C. dynamic thermal mechanical analysis tests were performed on the composite materials prepared in Examples 1-9 and Comparative Examples 1-2. The test results are shown in Table 1:

[0107] Table 1 Conductivity test

[0108]

[0109]

[0110] It can be seen from Table 1 that the electrical conductivity of Examples 1-9 is much higher than that of Comparative Examples 1-2, and the 25°C loss factor values ​​of Examples 1-9 are lower than those of Comparative Examples 1-2; this indicates that the composite material prepared by the present invention has better electrical conductivity and lower viscous loss, and can be well applied in the field of flexible electronic devices.

Claims

1. A method for preparing a conductive halogenated butyl rubber composite material, characterized in that: The preparation method comprises: The halogenated butyl rubber is mixed with an ionic crosslinking agent to react to obtain a halogenated butyl rubber ionomer having an ionic crosslinking network; The halogenated butyl rubber ionomer is mixed with a covalent crosslinking agent to react and obtain a halogenated butyl rubber polymer having a covalent-ionic hybrid crosslinking structure; The halogenated butyl rubber polymer is firstly immersed in a good solvent to reach swelling equilibrium, then transferred to a conductive filler dispersion for immersion, and dried to obtain a conductive halogenated butyl rubber composite material.

2. The method for preparing a conductive halogenated butyl rubber composite material according to claim 1, characterized in that: The ionic crosslinking agent is at least one of imidazole, 1-butylimidazole, 1-(3-aminopropyl)imidazole, 1-(2-hydroxyethyl)imidazole, 1-ethylimidazole, 1-vinylimidazole, 2-phenylimidazole, 1,2-dimethylimidazole, pyridine, 4-methylpyridine, 4-tert-butylpyridine, 4-(dimethylamino)pyridine, and 4-(dibutylamino)pyridine.

3. The method for preparing a conductive halogenated butyl rubber composite material according to claim 1, characterized in that: The covalent crosslinking agent is at least one of zinc oxide, sulfur, diisophenylene peroxide, N,N'-m-phenylene bismaleimide, phenolic resin and zinc chloride.

4. The method for preparing a conductive halogenated butyl rubber composite material according to claim 1, characterized in that: The good solvent is at least one of dichloromethane, chloroform dimethylformamide, dimethylacetamide, tetrahydrofuran, toluene, xylene and cyclohexane.

5. The method for preparing a conductive halogenated butyl rubber composite material according to claim 1, characterized in that: The conductive filler is at least one of carbon black, carbon nanotubes, graphene, reduced graphene oxide, graphite, carbon fiber, titanium carbide, and nanosilver.

6. The method for preparing a conductive halogenated butyl rubber composite material according to claim 1, characterized in that: The concentration of the conductive filler dispersion is 0.1-10%wt.

7. The method for preparing a conductive halogenated butyl rubber composite material according to claim 1, characterized in that: The weight ratio of the halogenated butyl rubber to the ionic crosslinking agent and the covalent crosslinking agent is 100:0.05-8:0.05-10.

8. A conductive halogenated butyl rubber composite material, characterized in that: The conductive halogenated butyl rubber composite material is prepared by the preparation method described in any one of claims 1 to 7.

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