Rubber composition, vulcanized rubber and preparation method and application of vulcanized rubber

Abstract

The invention relates to the field of rubber for flexible resistance sensors, in particular to a rubber composition, vulcanized rubber and a preparation method and application of the vulcanized rubber. The rubber composition comprises base rubber, a carbon-based filler, a vulcanizing agent, a vulcanization accelerator, a vulcanization activator and an anti-aging agent which are stored independently, and is characterized in that the base rubber is polydiene rubber, the carbon-based filler is a modified carbon-based filler, and the modified carbon-based filler has a structural unit; -R < 1 >-Si < X > < 2 >-R < 2 >-S < m >-R < 2 >- Wherein R1 is-COO <-> or-O <->; r2 is-(CH2) n-, and n is an integer from 1 to 5; s in Sm is a sulfur atom, and m is an integer from 2 to 8; x is a hydrolyzable organic group, and two or three X groups connected with Si are the same or different; the vulcanized rubber has excellent conductivity.

Description

Technical Field

[0001] The present invention relates to the field of rubber for flexible resistance sensors, and in particular to a rubber composition and vulcanized rubber, and a preparation method and application thereof. Background Art

[0002] Conductive rubber materials are widely used in various types of pressure sensors. Piezoresistive sensors have attracted widespread attention due to their simple structure, low energy consumption, high sensitivity coefficient, and good frequency response. Among them, conductive rubber sensors have conductive functions, low density, corrosion resistance, and electrical conductivity within dozens of orders of magnitude (the volume resistivity of conductive rubber materials ranges from 10 2 Ω·m~10 6 It has the advantages of adjusting the resistance between Ω·m and Ω·m, and often replaces metal material piezoresistive sensors and inorganic conductive material piezoresistive sensors, and is widely used in production and life.

[0003] CN105670297A discloses a conductive rubber material for a flexible sensor, a preparation method and an application thereof, wherein the conductive rubber material for a flexible sensor comprises the following components in the following weight proportions: 100 parts of a silicone rubber matrix, 5-100 parts of a conductive filler, 5-30 parts of a modified white carbon black, and 0.1-10 parts of a coupling agent, and the conductive rubber material is prepared by dispersing the conductive filler in a rubber material and cross-linking it by electron beam or gamma ray radiation. The silicone rubber matrix comprises a molecular main chain structure composed of alternating silicon atoms and oxygen atoms, and further, the silicone rubber matrix is ​​at least one of dimethyl silicone rubber, methyl vinyl silicone rubber, methyl vinyl phenyl silicone rubber, phenylene silicone rubber, fluorosilicone rubber, nitrile silicone rubber, and borosilicate rubber. The conductive filler is at least one of conductive carbon black, nanographite, carbon nanotubes, silver-plated powder, nickel powder, and nickel-plated powder. The resistivity of the conductive rubber material is in the range of 2.0×10 3 Ω·m to 1.0×10 10 Ω·m. In this patent, the conductive rubber matrix uses expensive silicone rubber, the conductive filler uses conductive carbon black, metal powder, etc., and the processing method uses a melt compound method. The conductive filler is not easy to disperse efficiently in the rubber matrix, which affects the further improvement of the conductive performance.

[0004] With the popularity of smart products, wearable electronic devices present a huge market prospect, but achieving high sensitivity, high resolution, low-cost manufacturing and complex signal detection of flexible electronic sensors is still a great challenge. As one of the main core component materials of sensors, the breadth of the adjustable resistivity range of conductive rubber materials and factors such as manufacturing costs will affect the future development of wearable devices. In addition, the compatibility of conductive fillers with rubber and their dispersion state in rubber will greatly affect the conductive properties of the composite material. Therefore, it is necessary to propose a method for preparing a conductive rubber composition that can solve the above problems. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects of the prior art that the conductive filler has poor compatibility with rubber and poor dispersion in rubber, as well as the defect that a large amount of expensive conductive filler needs to be filled to prepare low-resistivity rubber materials in the prior art, and to provide a rubber composition and vulcanized rubber and a preparation method and application thereof, wherein the vulcanized rubber has excellent conductive properties.

[0006] In order to achieve the above object, the first aspect of the present invention provides a rubber composition, the rubber composition comprising a base rubber, a carbon-based filler, a vulcanizing agent, a vulcanization accelerator, a vulcanization activator and an antioxidant, each of which is independently preserved, wherein the base rubber is a polydiene rubber, the carbon-based filler is a modified carbon-based filler, and the modified carbon-based filler has a structural unit represented by formula (1);

[0007] -R 1 -SiX 2 -R 2 -S m -R 2 -SiX 3 , formula (1);

[0008] Among them, R 1 is -COO- or -O-; R 2 For -(CH 2 )n-, n is an integer from 1 to 5;

[0009] S m Where S is a sulfur atom, and m is an integer of 2-8;

[0010] X is a hydrolyzable organic group, and the two or three X groups connected to Si are the same or different.

[0011] A second aspect of the present invention provides a vulcanized rubber, wherein the vulcanized rubber is obtained by mixing and vulcanizing the rubber composition described above.

[0012] The third aspect of the present invention provides a method for preparing the aforementioned vulcanized rubber, wherein the method comprises:

[0013] (1) Modified carbon-based filler: dispersing the carbon-based filler in N,N-dimethylformamide to obtain a first dispersion, contacting the first dispersion with a coupling agent to perform a first reaction, filtering, washing and drying to obtain a modified carbon-based filler;

[0014] (2) Base rubber / carbon-based filler masterbatch:

[0015] a) dispersing the modified carbon-based filler in N,N-dimethylformamide to obtain a second dispersion;

[0016] b) chopping the base rubber and dissolving it in THF to obtain a base rubber solution;

[0017] c) adding the second dispersion dropwise to the base rubber solution to obtain a mixed solution, so that the modified carbon-based filler is compounded with the base rubber solution to obtain a base rubber / carbon-based filler masterbatch;

[0018] (3) Mixing and vulcanizing the base rubber / carbon-based filler masterbatch, the vulcanizing agent, the vulcanization accelerator, the vulcanization activator and the antioxidant to obtain a vulcanized rubber.

[0019] A fourth aspect of the present invention provides a use of the aforementioned vulcanized rubber in the preparation of a flexible resistance sensor.

[0020] Through the above technical scheme, the rubber composition provided by the present invention contains polydiene rubber and modified carbon-based filler, and the modified carbon-based filler is efficiently dispersed in the rubber matrix by a solution compounding method, and the modified group of the modified carbon-based filler produces a covalent chemical bond with the rubber matrix, so that the carbon-based filler and the rubber matrix have good interface bonding performance, and the vulcanized rubber has excellent conductive properties. DETAILED DESCRIPTION

[0021] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0022] As mentioned above, the first aspect of the present invention provides a rubber composition, the rubber composition comprising a base rubber, a carbon-based filler, a vulcanizing agent, a vulcanization accelerator, a vulcanization activator and an antioxidant, each of which is independently preserved, wherein the base rubber is a polydiene rubber, the carbon-based filler is a modified carbon-based filler, and the modified carbon-based filler has a structural unit represented by formula (1);

[0023] -R 1 -SiX 2 -R 2 -S m -R 2 -SiX 3 , formula (1);

[0024] Among them, R 1 is -COO- or -O-; R 2 For -(CH 2 )n-, n is an integer from 1 to 5;

[0025] S m Where S is a sulfur atom, and m is an integer of 2-8;

[0026] X is a hydrolyzable organic group, and the two or three X groups connected to Si are the same or different.

[0027] The inventors of the present invention unexpectedly discovered during in-depth research that carbon-based fillers such as graphene are first modified using active groups such as hydroxyl groups and epoxy groups on their surfaces, and functional groups that can react with carbon-carbon double bonds in polydiene rubber molecules are grafted thereon (for example, the functional groups can be monosulfide bonds and / or polysulfide bonds); then compounded with polydiene rubber in a solution, the functional groups of the modified graphene and the polydiene rubber are efficiently dispersed in the solution, and the graphene is reduced during the solution compounding process; further, during the vulcanization process of the rubber composition, this dispersed state is effectively locked by the covalent bonds formed by the reaction of the functional groups of the modified graphene with the carbon-carbon double bonds of the polydiene rubber, and the conductive graphene is stably and moderately dispersed, which can ensure that the rubber composite material (vulcanized rubber) has a lower volume resistivity when a lower amount of graphene is used. The polydiene rubber graphene conductive composition prepared by the method of the present invention has excellent performance as a flexible resistance sensor material.

[0028] According to the present invention, after the graphene oxide is modified, part of the hydroxyl groups or epoxy groups are converted into -R 1 -SiX 2 -R 2 -S m -R 2 -SiX 3 , wherein m is an integer of 2-8; preferably, m is an integer of 4-8; more preferably, m is an integer of 4-6.

[0029] According to the present invention, preferably, X is selected from one or more of methoxy, ethoxy and chlorine.

[0030] According to the present invention, the carbon-based filler is graphene; preferably, the carbon-based filler is reduced graphene and / or oxidized graphene; more preferably, the carbon-based filler is graphene oxide.

[0031] In the present invention, the ratio of the number of carbon atoms to the number of oxygen atoms in the graphene is C:O=(2-14):1, preferably (6-14):1; the content of C, H, and O elements in the graphene is greater than 98 atomic %.

[0032] According to the present invention, the reduced graphene is different from the oxidized graphene in that the ratio of the number of carbon atoms to the number of oxygen atoms is different.

[0033] In the present invention, the ratio of carbon atoms to oxygen atoms in the graphene oxide is less than 7:1, preferably (3-6):1, the number of layers of the graphene oxide is 1-10, and the specific surface area is 10-1100m 2 / g, volume resistivity is 10 -6 Ω·m to 10 -5 Ω·m.

[0034] In the present invention, the ratio of carbon atoms to oxygen atoms in the reduced graphene is greater than 7:1, preferably (8-13):1.

[0035] According to the present invention, the modified carbon-based filler is prepared by reacting the carbon-based filler with a coupling agent; preferably, the coupling agent is a silane coupling agent having a structure shown in formula (2);

[0036] R-(SiX 1 X 2 X 3 ) 2 , formula (2);

[0037] Wherein, R is selected from aliphatic or aromatic hydrocarbon groups containing one or more groups selected from vinyl, epoxy, amino, methacryloyloxy, thiol and polysulfide bonds;

[0038] X 1 , X 2 and X 3 are the same or different and are each independently selected from methoxy, ethoxy or chloro.

[0039] According to the present invention, preferably, the coupling agent is selected from one or more of vinyl tri(β-methoxyethoxy)silane, bis-[3-(triethoxysilyl)propyl]tetrasulfide, γ-mercaptopropyltriethoxysilane and bis-[3-(triethoxysilyl)propyl]-disulfide; more preferably, the coupling agent is bis-[3-(triethoxysilyl)propyl]tetrasulfide and / or bis-[3-(triethoxysilyl)propyl]-disulfide.

[0040] According to the present invention, the base rubber is a polydiene elastomer (polydiene rubber), preferably a polyisoprene elastomer, and more preferably, the base rubber is a high-cis polyisoprene elastomer.

[0041] According to the present invention, the content of cis-1,4-isoprene structural units in the high-cis polyisoprene is 95-97wt%, the content of trans-1,4-isoprene structural units is 0-1wt%, and the content of 3,4-isoprene structural units is 2-4wt%; preferably, the content of cis-1,4-isoprene structural units in the high-cis polyisoprene is 96.0-96.9wt%, the content of trans-1,4-isoprene structural units is 0.1-0.6wt%, and the content of 3,4-isoprene structural units is 2.5-3.5wt%.

[0042] According to the present invention, the number average molecular weight of the base rubber is 4×10 5 g / mol-5×10 5 g / mol, weight average molecular weight is 1.3×10 5 g / mol-1.7×10 5 g / mol, and the molecular weight distribution index is 2.3-3.8; preferably, the number average molecular weight of the base rubber is 4.7×10 5 g / mol-5×10 5 g / mol, weight average molecular weight is 1.5×10 5 g / mol-1.6×10 5 g / mol, and the molecular weight distribution index is 3.2-3.5.

[0043] According to the present invention, relative to 100 parts by weight of the base rubber, the content of the carbon-based filler is 0.1-5 parts by weight, the content of the vulcanizing agent is 0.1-5 parts by weight, the content of the vulcanization accelerator is 0.5-2 parts by weight, and the content of the antioxidant is 0.5-2 parts by weight; preferably, relative to 100 parts by weight of the base rubber, the content of the carbon-based filler is 0.5-5 parts by weight, the content of the vulcanizing agent is 1-5 parts by weight, the content of the vulcanization accelerator is 1-2 parts by weight, and the content of the antioxidant is 1-2 parts by weight.

[0044] According to the present invention, the vulcanizing agent includes one or more of insoluble sulfur, dithiomorpholine and dimorpholine tetrasulfide.

[0045] According to the present invention, the vulcanization accelerator is a benzothiazolyl sulfenamide vulcanization accelerator, preferably one or more of N-tert-butyl-2-benzothiazolyl sulfenamide, 2,2'-dibenzothiazyl disulfide, N-tert-butyl-bis(2-benzothiazolyl)sulfenimide, N-cyclohexyl-2-benzothiazolyl sulfenamide and N-cyclohexyl-2-benzothiazolyl sulfenamide.

[0046] According to the present invention, the vulcanization activator includes an inorganic activator and / or an organic activator, preferably an inorganic activator; the inorganic activator includes one or more of indirect zinc oxide, direct zinc oxide and active zinc oxide; the organic activator includes one or more of stearic acid, lauric acid and caprylic acid. In the present invention, it should be noted that when the vulcanization activator is an inorganic activator, the content of the vulcanization activator is 4-11 parts by weight, preferably 5-10 parts by weight, relative to 100 parts by weight of the base rubber; when the vulcanization activator is an organic activator, the content of the vulcanization activator is 2-8 parts by weight, preferably 3-6 parts by weight, relative to 100 parts by weight of the base rubber.

[0047] According to the present invention, the antioxidant is selected from one or more of quinoline, benzimidazole and amine antioxidants; wherein the quinoline antioxidant may be a 2,2,4-trimethyl-1,2-dihydroquinoline polymer; the benzimidazole antioxidant may be a 2-mercaptobenzimidazole zinc salt; the amine antioxidant may be selected from one or more of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, N-isopropylphenyl-N'-phenyl-p-phenylenediamine, N-cyclohexyl-N'-phenyl-p-phenylenediamine and N-phenyl-2-naphthylamine.

[0048] A second aspect of the present invention provides a vulcanized rubber, wherein the vulcanized rubber is obtained by mixing and vulcanizing the rubber composition described above.

[0049] According to the present invention, the volume resistivity of the vulcanized rubber is 1×10 -2 Ω·m to 1×10 4 Ω·m, preferably 5×10 -2 Ω·m to 8×10 3 Ω·m.

[0050] The third aspect of the present invention provides a method for preparing the aforementioned vulcanized rubber, wherein the method comprises:

[0051] (1) Modified carbon-based filler: dispersing the carbon-based filler in N,N-dimethylformamide to obtain a first dispersion, contacting the first dispersion with a coupling agent to perform a first reaction, filtering, washing and drying to obtain a modified carbon-based filler;

[0052] (2) Base rubber / carbon-based filler masterbatch:

[0053] a) dispersing the modified carbon-based filler in N,N-dimethylformamide to obtain a second dispersion;

[0054] b) chopping the base rubber and dissolving it in THF to obtain a base rubber solution;

[0055] c) adding the second dispersion dropwise to the base rubber solution to obtain a mixed solution, so that the modified carbon-based filler is compounded with the base rubber solution to obtain a base rubber / carbon-based filler masterbatch;

[0056] (3) Mixing and vulcanizing the base rubber / carbon-based filler masterbatch, the vulcanizing agent, the vulcanization accelerator, the vulcanization activator and the antioxidant to obtain a vulcanized rubber.

[0057] According to the present invention, in step (1), the amount of the carbon-based filler is 0.001-0.01 g relative to 1 mL of N,N-dimethylformamide; preferably, the amount of the carbon-based filler is 0.005-0.01 g relative to 1 mL of N,N-dimethylformamide, and the amount of the coupling agent is 1.0×10 -6 g-2.0×10 -6 g.

[0058] According to the present invention, the amount of the coupling agent is 1.5×10 -4 mol-2.5×10 -4 mol; preferably, relative to 1g of the carbon-based filler, the amount of the coupling agent is 1.8×10 -4 mol-2.3×10 - 4 mol.

[0059] According to the present invention, the conditions of the first reaction include: temperature of 60-80° C. and time of 23-25 ​​h.

[0060] According to the present invention, in step (2), the modified carbon-based filler is compounded with the solution of the base rubber, specifically, the second dispersion is added dropwise to the base rubber solution to obtain a mixed solution; the mixed solution is contacted with hydrazine hydrate for a second reaction and then dissolved in a methanol solution, and then dried to obtain a base rubber / carbon-based filler masterbatch. In the present invention, hydrazine hydrate plays a reducing role, reducing graphene oxide to graphene, thereby improving the electrical conductivity of the rubber composition.

[0061] According to the present invention, in step (2), the concentration of the second dispersion is 1-10 mg / L, preferably 2-9 mg / L.

[0062] According to the present invention, the amount of the base rubber is 10-100 g, preferably 20-90 g, relative to 1000 mL of THF.

[0063] According to the present invention, the dripping rate is 1-5 mL / min.

[0064] According to the present invention, relative to 1g of the modified carbon-based filler, the amount of hydrazine hydrate used is 20-40mL, preferably 25-35mL.

[0065] According to the present invention, the conditions of the second reaction include: temperature of 60-80° C. and time of 23-25 ​​h.

[0066] According to the present invention, the conditions for the drying treatment include: a temperature of 50-70° C. and a time of 45-50 hours.

[0067] According to the present invention, the vulcanization temperature is 140-160° C., the vulcanization pressure is 3.5-7 MPa, and the vulcanization time is 0.15-1 hour.

[0068] According to a preferred embodiment of the present invention, a method for preparing vulcanized rubber comprises:

[0069] Step 1: Modification of graphene

[0070] Dispersing graphene in N,N-dimethylformamide (DMF for short, the ratio of graphene to DMF, i.e., graphene / mLDMF is 0.001-0.01 g), and fully dispersing it by ultrasound;

[0071] Then, a coupling agent (Si69, bis-(3-(triethoxysilyl)propyl)-tetrasulfide) was added (the ratio of the number of moles of coupling agent to the weight of graphene, i.e., coupling agent / g graphene was 1.5×10 -4 mol to 2.5×10 -4mol), reacted at 70°C with stirring for 24 hours to obtain a modified graphene oxide mixed solution, the obtained mixed solution was filtered, washed with pure DMF 2-3 times, and then dried in a vacuum oven at 40°C for 48 hours to obtain Si69-modified graphene.

[0072] Step 2: Compounding of modified graphene and rubber solution

[0073] The Si69-modified graphene was re-ultrasonic dispersed in DMF at a concentration of 1-10 mg / L to prepare modified rubber nanocomposites with different graphene contents;

[0074] Then add the shredded polydiene rubber into THF and stir for 24 hours to fully dissolve it. Add the modified graphene oxide solution dropwise into the dissolved polydiene rubber solution according to the proportion and stir thoroughly to mix them evenly.

[0075] Subsequently, hydrazine hydrate was added in a ratio of 1 g of modified graphene oxide to 20-40 mL of hydrazine hydrate, and the reaction was stirred at 70° C. for 24 hours to in-situ reduce the modified graphene oxide to surface-modified graphene;

[0076] The obtained mixed solution was poured into a proper amount of methanol solution to precipitate the graphene-modified rubber composite, which was then placed in an oven at 60° C. and dried for 48 hours to obtain a polydiene rubber graphene masterbatch.

[0077] Step 3: Mixing of rubber composition

[0078] The mixing method is banburying, and the banburying process includes: firstly, the polydiene rubber graphene masterbatch, vulcanization activator and antioxidant prepared above are subjected to the first stage banburying, and the mixing is carried out at a temperature of 100-150°C for 3-5 minutes; then, the vulcanizer and the vulcanization accelerator are added to carry out the second stage banburying, and the mixing is continued for 1-3 minutes at a temperature not higher than 115°C.

[0079] Step 4: Vulcanization of the rubber composition

[0080] The vulcanization temperature is 140-160°C, the vulcanization pressure is 3.5-7MPa, and the vulcanization time is 0.15-1 hour.

[0081] A fourth aspect of the present invention provides a use of the aforementioned vulcanized rubber in the preparation of a flexible resistance sensor.

[0082] The present invention will be described in detail below through examples.

[0083] In the following examples and comparative examples:

[0084] Experimental materials:

[0085] Isoprene rubber (IR, high cis polyisoprene): The content of cis 1,4-isoprene structural units in IR is 96.9wt%, the content of trans 1,4-isoprene structural units is 0.6wt%, and the content of 3,4-isoprene structural units is 2.5wt%; the number average molecular weight is 4.7×10 5 g / mol, weight average molecular weight is 1.5×10 5 g / mol, molecular weight distribution index is 3.2, produced by rare earth catalyst process, industrial product, block solid, brand IR80, produced by Beijing Yanshan Branch of China Petrochemical Corporation.

[0086] Graphene oxide GO: powdered sample, produced by Xiamen Kaina Graphene Technology Co., Ltd.; the ratio of carbon atoms to oxygen atoms in the graphene oxide is C:O=6.4:1; the content of C, H, and O elements in the graphene is greater than 98 atomic %; the number of layers of the graphene oxide is 5, and the specific surface area is 1056m 2 / g, volume resistivity is 5.2×10 -5 Ω·m.

[0087] DMF (N,N-dimethylformamide), Si69 (i.e., (bis-(3-(triethoxysilyl)propyl)-tetrasulfide)), cyclohexane, ethanol, vulcanization accelerator CBS (N-cyclohexyl-2-benzothiazolesulfonamide), antioxidant 4010 (N-cyclohexyl-N'-phenyl-p-phenylenediamine), etc. were purchased from Beijing Inokai Chemical Reagent Company and were chemically pure.

[0088] Example 1

[0089] This example is intended to illustrate the vulcanized rubber prepared using the rubber composition and method of the present invention.

[0090] (1) 1.5 g of graphene oxide GO was dispersed in 300 mL of DMF (N,N-dimethylformamide), and ultrasonically dispersed at a power of 1000 W and an ultrasonic frequency of 10 kHz to obtain a first dispersion; then Si69 (i.e., bis-(3-(triethoxysilyl)propyl)-tetrasulfide)) was added, wherein the ratio of the molar number of Si69 to the weight of graphene was 1.8×10 - 4 mol / g, reacted at 70°C with a stirring rate of 70 rpm for 24 hours to obtain a modified graphene oxide mixed solution, filtered the obtained mixed solution, washed with pure DMF 2-3 times, and then dried in a vacuum oven at 40°C for 48 hours to obtain Si69-modified graphene;

[0091] The Si69-modified graphene includes a structural unit shown in formula (1);

[0092] -R 1 -SiX 2 -R 2 -S m -R 2 -SiX 3 , formula (1);

[0093] Among them, R 1 is -COO- or -O-; R 2 For -(CH 2 )n-, n is an integer of 3;

[0094] m is an integer of 4;

[0095] S is a sulfur atom;

[0096] X is an ethoxy group.

[0097] (2) The graphene modified with Si69 was re-ultrasonic dispersed in DMF to obtain a modified graphene oxide solution (second dispersion) with a concentration of 5 mg / L; 20 g of shredded IR was added to 1000 mL of THF to obtain a basic rubber solution, which was stirred for 24 hours to fully dissolve it; the modified graphene oxide solution was added dropwise to the dissolved IR in proportion, and stirred thoroughly to mix them evenly, thereby preparing modified rubber nanocomposites with different graphene contents; subsequently, hydrazine hydrate was added in a ratio of 1 g of modified graphene oxide to 30 mL of hydrazine hydrate, and the reaction was stirred at 70°C for 24 hours, and the modified graphene oxide was in situ reduced to modified graphene.

[0098] The obtained mixed solution was poured into an appropriate amount of methanol solution to precipitate the graphene-modified rubber composite, which was then placed in an oven at 60° C. to dry for 48 h.

[0099] After drying, the rubber composition was mixed in two stages in an internal mixer according to the formula of the rubber composition in Table 1 and the mixing process steps of the internal mixer shown in Table 2 to obtain a mixed rubber.

[0100] (3) The mixed rubber was then compression-vulcanized at a temperature of 143°C and a pressure of 15 MPa into a sheet of vulcanized rubber with a thickness of 2 mm for testing.

[0101] Embodiment 2-6

[0102] This example is intended to illustrate the vulcanized rubber prepared using the rubber composition and method of the present invention.

[0103] The vulcanized rubber was prepared in the same manner as in Example 1, and the same modified graphene (i.e., Si69-modified graphene) as in Example 1 was used, except that the rubber compound was prepared by two stages of internal mixing in an internal mixer according to the formula of the rubber composition in Table 1 and the internal mixer mixing processing steps shown in Table 2.

[0104] The mixed rubber was then compression-vulcanized at a temperature of 143° C. and a pressure of 15 MPa into a sheet of vulcanized rubber with a thickness of 2 mm for testing.

[0105] Example 7

[0106] This example is intended to illustrate the vulcanized rubber prepared using the rubber composition and method of the present invention.

[0107] The vulcanized rubber was prepared in the same manner as in Example 1, except that the coupling agent added was Si75 (silane coupling agent Si75, i.e., bis-[3-(triethoxysilyl)propyl]-disulfide).

[0108] The Si75-modified graphene includes a structural unit shown in formula (1);

[0109] -R 1 -SiX 2 -R 2 -S m -R 2 -SiX 3 , formula (1);

[0110] Among them, R 1 is -COO- or -O-; R 2 For -(CH 2 ) n -, n is an integer of 3;

[0111] m is an integer of 2;

[0112] S is a sulfur atom;

[0113] X is an ethoxy group.

[0114] According to the formula of the rubber composition in Table 1 and the mixing process steps in the internal mixer shown in Table 2, a rubber compound is prepared by two-stage internal mixing in the internal mixer.

[0115] The mixed rubber was then compression-vulcanized at a temperature of 143° C. and a pressure of 15 MPa into a sheet of vulcanized rubber with a thickness of 2 mm for testing.

[0116] Comparative Example 1

[0117] Comparative Example DH1 is used to illustrate the preparation of the rubber composition provided by the present invention. Comparative Example DH1 does not contain graphene carbon-based fillers, and the base rubber solid isoprene rubber industrial product and other rubber additives are prepared according to the formula of the rubber composition of DH1 in Table 1, and the mixed rubber is prepared by two stages of internal mixing in the internal mixer according to the internal mixer mixing process steps shown in Table 2. Then, it is molded and vulcanized into a sheet material with a thickness of 2 mm under the conditions of temperature 143°C and pressure 15MPa for testing.

[0118] Comparative Example 2

[0119] Comparative Example DH2 is used to illustrate the preparation of the rubber composition provided by the present invention. The preparation method of the rubber composition of Comparative Example DH2 is similar to that of Example 1, except that Comparative Example DH2 uses graphene oxide (not modified by Si69) to compound with IR solution and simultaneously reduce in situ. According to the formula of the rubber composition of DH2 in Table 1, the mixed rubber is obtained by two stages of internal mixing in the internal mixer according to the internal mixer mixing processing steps shown in Table 2. Then, it is molded and vulcanized into a sheet material with a thickness of 2 mm at a temperature of 143°C and a pressure of 15MPa for testing.

[0120] Comparative Example 3

[0121] The vulcanized rubber was prepared in the same manner as in Example 1, except that the coupling agent added was diethyldiethoxysilane.

[0122] The modified graphene oxide is -R 1 -Si(X)-(R 2 ) 2 .

[0123] Among them, R 1 is -COO- or -O-; R 2 -CH 2 CH 3 , X is -OCH 2 CH 3 .

[0124] According to the formula of the rubber composition in Table 1 and the mixing process steps in the internal mixer shown in Table 2, a rubber compound is prepared by two-stage internal mixing in the internal mixer.

[0125] The mixed rubber was then compression-vulcanized at a temperature of 143° C. and a pressure of 15 MPa into a sheet of vulcanized rubber with a thickness of 2 mm for testing.

[0126] Comparative Example 4

[0127] The vulcanized rubber was prepared in the same manner as in Example 1, except that butyl rubber IIR was used instead of IR.

[0128] According to the formula of the rubber composition in Table 1 and the mixing process steps in the internal mixer shown in Table 2, a rubber compound is prepared by two-stage internal mixing in the internal mixer.

[0129] The mixed rubber was then compression-vulcanized at a temperature of 143° C. and a pressure of 15 MPa into a sheet of vulcanized rubber with a thickness of 2 mm for testing.

[0130] Comparative Example 5

[0131] The vulcanized rubber was prepared in the same manner as in Example 1, except that the modified graphene was mixed with the solid of the base rubber IR in a solid powder state.

[0132] According to the formula of the rubber composition in Table 1 and the mixing process steps in the internal mixer shown in Table 2, a rubber compound is prepared by two-stage internal mixing in the internal mixer.

[0133] The mixed rubber was then compression-vulcanized at a temperature of 143° C. and a pressure of 15 MPa into a sheet of vulcanized rubber with a thickness of 2 mm for testing.

[0134] Table 1

[0135]

[0136]

[0137] Table 1 (continued)

[0138] raw material Example H3 Example H4 Embodiment H5 Example H6 Example H7 IR 100 100 100 100 100 Modified graphene 2.2 2.6 3.0 3.5 3.7 Graphene oxide - - - - - Stearic acid 3.5 3 2.5 2 4 ZnO 5.5 4 4.5 5 6 Antioxidant 4010 2 1.5 1 1 0.8 Accelerator CBS 1 1 1.5 1 1.5 sulfur 4 3 1 2 0.8

[0139] In Table 1 and Table 1 (Continued), it should be noted that:

[0140] The “modified graphene” in Examples 1-6 is “Si69-modified graphene”;

[0141] The “modified graphene” in Example 7 is “Si75-modified graphene”;

[0142] The "modified graphene" in Comparative Example 4 is "Si69-modified graphene";

[0143] The "modified graphene" in Comparative Example 3 is "graphene modified by coupling agent diethyldiethoxysilane".

[0144] Table 2

[0145]

[0146] Test Case

[0147] The test examples are used to illustrate the performance test of the rubber composition provided by the present invention.

[0148] The volume resistivity of the 2 mm thick modified graphene rubber composition vulcanized rubber sheets of comparative examples DH1-DH5 and examples H1-7 was tested, and the results are shown in Table 3, the volume resistivity of the vulcanized rubber compositions of comparative examples DH1-DH5 and examples H1-7.

[0149] The volume resistivity of a 2 mm thick vulcanized film of the modified graphene rubber composition of the rubber material was tested on a four-probe resistivity meter (model RTS-8, produced by Anhemeng Technology Development Co., Ltd.).

[0150] As can be seen from Table 3, when the graphene content in the modified graphene rubber composition increases from 0phr to 3.5phr, the volume resistivity of the vulcanized rubber of the composition is significantly reduced, and when the graphene content is greater than 1phr, the volume resistivity is greatly reduced. Compared with the rubber composition without modified graphene, the volume resistivity of the composition with a graphene content of 3.5phr is reduced by 6 orders of magnitude. When the graphene content is above 1.5phr, the graphene rubber composition material can be used for conductive rubber composite materials such as flexible resistive pressure sensors (10 2 Ω·m~10 6 Ω·m) is used.

[0151] Table 3

[0152] project Content / phr Volume resistivity of the composition ρ / Ω·m Comparative Example DH1 0 <![CDATA[2.56×10 7 ]]> Comparative Example DH2 1.0 <![CDATA[2.00×10 7 ]]> Comparative Example DH3 1.0 <![CDATA[1.25×10 7 ]]> Comparative Example DH4 1.0 <![CDATA[3.57×10 7 ]]> Comparative Example DH5 1.0 <![CDATA[2.78×10 7 ]]> Example H1 1.0 <![CDATA[4.27×10 6 ]]> Example H2 1.5 <![CDATA[3.85×10 5 ]]> Example H3 2.2 <![CDATA[5.26×10 4 ]]> Example H4 2.6 <![CDATA[1.82×10 4 ]]> Embodiment H5 3.0 <![CDATA[2.50×10 3 ]]> Example H6 3.5 47.6 Example H7 3.7 50.2

[0153] It can be seen from the above results that the rubber composition of the present invention has a lower volume resistivity because the graphene in the rubber composition is modified to become modified graphene containing functional groups, and the modified graphene is efficiently dispersed in the rubber matrix by a solution compounding method. At the same time, the graphene is reduced in situ during the compounding process, and during the vulcanization process of the rubber composition, the functional groups of the modified graphene produce covalent chemical bonds with the rubber matrix, so that the filler and the rubber matrix have better interface bonding performance, so that the graphene has a smaller percolation threshold in the rubber composition (the percolation threshold is about 1phr), and when the graphene content is greater than the percolation threshold, the rubber composition has excellent conductive properties.

[0154] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A rubber composition, comprising a base rubber, a carbon-based filler, a vulcanizing agent, a vulcanization accelerator, a vulcanization activator and an antioxidant, each of which is independently preserved, characterized in that: The base rubber is a polydiene rubber, the carbon-based filler is a modified carbon-based filler, and the modified carbon-based filler has a structural unit represented by formula (1); -R 1 -SiX2-R 2 -S m -R 2 -SiX3, formula (1); Among them, R 1 is -COO- or -O-; R 2 -(CH2)n-, n is an integer from 1 to 5; S m Where S is a sulfur atom, and m is an integer of 2-8; X is a hydrolyzable organic group, and the two or three X groups connected to Si are the same or different.

2. The rubber composition according to claim 1, wherein n is an integer from 1 to 3; m is an integer from 4 to 8; X is selected from one or more of methoxy, ethoxy and chlorine.

3. The rubber composition according to claim 1 or 2, wherein: The modified carbon-based filler is prepared by reacting the carbon-based filler with a coupling agent; Preferably, the coupling agent is a silane coupling agent having a structure shown in formula (2); R-(SiX 1 X 2 X 3 )2, formula (2); Wherein, R is selected from aliphatic or aromatic hydrocarbon groups containing one or more groups selected from vinyl, epoxy, amino, methacryloyloxy, thiol and polysulfide bonds; X 1 , X 2 and X 3 are the same or different and are each independently selected from methoxy, ethoxy or chloro; Preferably, the coupling agent is selected from one or more of vinyl tri(β-methoxyethoxy)silane, bis-(3-(triethoxysilane)propyl)-tetrasulfide, γ-mercaptopropyltriethoxysilane and bis-[3-(triethoxysilane)propyl]-disulfide; More preferably, the coupling agent is bis-[3-(triethoxysilyl)propyl]tetrasulfide and / or bis-[3-(triethoxysilyl)propyl]-disulfide.

4. The rubber composition according to any one of claims 1 to 3, wherein The carbon-based filler is graphene; Preferably, the carbon-based filler is reduced graphene and / or graphene oxide; Preferably, the carbon-based filler is graphene oxide.

5. The rubber composition according to claim 1, wherein The base rubber is a polydiene elastomer, preferably a polyisoprene elastomer; Preferably, the base rubber is a high-cis polyisoprene elastomer; More preferably, the content of cis-1,4-isoprene structural units in the high-cis polyisoprene is 95-97 wt %, the content of trans-1,4-isoprene structural units is 0-1 wt %, and the content of 3,4-isoprene structural units is 2-4 wt %; And / or, the number average molecular weight of the base rubber is 4×10 5 g / mol-5×10 5 g / mol, weight average molecular weight is 1.3×10 5 g / mol-1.7×10 5 g / mol, and the molecular weight distribution index is 2.3-3.

8.

6. The rubber composition according to any one of claims 1 to 5, wherein: Relative to 100 parts by weight of the base rubber, the content of the carbon-based filler is 0.1-5 parts by weight, the content of the vulcanizing agent is 0.1-5 parts by weight, the content of the vulcanization accelerator is 0.5-2 parts by weight, and the content of the antioxidant is 0.5-2 parts by weight; And / or, the vulcanization activator includes an inorganic activator and / or an organic activator; and / or, when the vulcanization activator is an inorganic activator, the content of the vulcanization activator is 4-11 parts by weight, preferably 5-10 parts by weight, relative to 100 parts by weight of the base rubber; And / or, when the vulcanization activator is an organic activator, the content of the vulcanization activator is 2-8 parts by weight, preferably 3-6 parts by weight, relative to 100 parts by weight of the base rubber.

7. A vulcanized rubber, characterized in that: The vulcanized rubber is obtained by mixing and vulcanizing the rubber composition according to any one of claims 1 to 6.

8. The vulcanized rubber according to claim 7, wherein The volume resistivity of the vulcanized rubber is 1×10 -2 Ω·m to 1×10 4 Ω·m.

9. A method for preparing the vulcanized rubber according to claim 7 or 8, characterized in that: The method includes: (1) Modified carbon-based filler: dispersing the carbon-based filler in N,N-dimethylformamide to obtain a first dispersion, contacting the first dispersion with a coupling agent to perform a first reaction, filtering, washing and drying to obtain a modified carbon-based filler; (2) Base rubber / carbon-based filler masterbatch: a) dispersing the modified carbon-based filler in N,N-dimethylformamide to obtain a second dispersion; b) chopping the base rubber and dissolving it in THF to obtain a base rubber solution; c) adding the second dispersion dropwise to the base rubber solution to obtain a mixed solution, so that the modified carbon-based filler is compounded with the base rubber solution to obtain a base rubber / carbon-based filler masterbatch; (3) Mixing and vulcanizing the base rubber / carbon-based filler masterbatch, the vulcanizing agent, the vulcanization accelerator, the vulcanization activator and the antioxidant to obtain a vulcanized rubber.

10. The method according to claim 9, wherein: In step (1), the amount of the carbon-based filler is 0.001-0.01 g relative to 1 mL of N,N-dimethylformamide; Preferably, the amount of the coupling agent is 1.5×10 -4 mol-2.5×10 -4 mol; And / or, the conditions of the first reaction include: temperature of 60-80° C. and time of 23-25 ​​h.

11. The method according to claim 9, wherein: In step (2), the concentration of the second dispersion is 1-10 mg / L; and / or, relative to 1000 mL of THF, the amount of the base rubber is 10-100 g; And / or, the dripping rate is 1-5 mL / min.

12. Use of the vulcanized rubber according to claim 7 or 8 in preparing a flexible resistance sensor.

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