Conductive silica gel, preparation method thereof and silica gel key
阅读说明：本技术 导电硅胶及其制备方法和一种硅胶按键 (Conductive silica gel, preparation method thereof and silica gel key ) 是由 邹坚强 沈海能 于 2021-08-24 设计创作，主要内容包括：本发明公开了一种导电硅胶及其制备方法和一种硅胶按键。一种导电硅胶,由包括如下重量份的原料制成：硅橡胶40～60份、改性导电填料3～5份、硫化剂0.5～1.5份；所述改性导电填料为氧化石墨烯包覆碳化硅而成的氮化硅-氧化石墨微粒,所述改性导电具有核壳结构。本申请制得的导电硅胶体积电阻较小,导电性能佳,且具有较好的热稳定性。(The invention discloses conductive silica gel, a preparation method thereof and a silica gel key. The conductive silica gel is prepared from the following raw materials in parts by weight: 40-60 parts of silicon rubber, 3-5 parts of modified conductive filler and 0.5-1.5 parts of vulcanizing agent; the modified conductive filler is silicon nitride-graphite oxide particles formed by coating silicon carbide with graphene oxide, and the modified conductive filler has a core-shell structure. The conductive silica gel prepared by the method has the advantages of small volume resistance, good conductivity and good thermal stability.)
1. The conductive silica gel is characterized by being prepared from the following raw materials in parts by weight:
40-60 parts of silicone rubber
3-5 parts of modified conductive filler
0.5-1.5 parts of a vulcanizing agent;
the modified conductive filler is silicon nitride-graphite oxide particles formed by coating silicon carbide with graphene oxide, and the modified conductive filler has a core-shell structure.
2. The conductive silica gel of claim 1, wherein the modified conductive filler is prepared by the steps of:
silicon nitride modification treatment: ultrasonically dispersing silicon nitride in a solvent to prepare a silicon nitride suspension, adding an aminosilane coupling agent into the silicon nitride suspension, wherein the weight ratio of the silicon nitride to the aminosilane coupling agent is 1 (0.05-0.15), uniformly mixing to prepare a first reaction solution, heating the first reaction solution to 55-65 ℃, and carrying out heat preservation reaction for 6-10 hours to obtain modified silicon nitride;
preparing a filler: ultrasonically dispersing modified silicon nitride in a solvent to prepare a modified silicon nitride solution, adding a graphene oxide dispersion solution into the modified silicon nitride solution, wherein the weight ratio of silicon nitride to graphene oxide is 1 (0.1-0.2), uniformly mixing to prepare a second reaction solution, heating the second reaction solution to 30-50 ℃, and carrying out heat preservation reaction for 3-4 hours to obtain the modified conductive filler.
3. A conductive silica gel according to claim 2, wherein: the weight ratio of the aminosilane coupling agent to the graphene oxide to the silicon nitride is 0.1:0.1: 1.
4. A conductive silica gel according to claim 2, wherein: and in the step of silicon nitride modification treatment, dilute nitric acid is added into the silicon nitride suspension before the aminosilane coupling agent is added, and the pH value of the silicon nitride suspension is adjusted to 3-5.
5. A conductive silica gel according to claim 2, wherein: the aminosilane coupling agent is one or more of bis- [3- (trimethoxy silicon) -propyl ] -amine, N-dimethyl-3-aminopropyl trimethoxy silane and N- (2-aminoethyl) -3-aminopropyl triethoxy silane.
6. A conductive silica gel according to claim 1, wherein: the silicone rubber is methyl vinyl silicone rubber.
7. A conductive silica gel according to claim 6, wherein: the mole fraction of vinyl chain units of the methyl vinyl silicone rubber is 0.03-0.24%.
8. The method of any one of claims 1-7, comprising the steps of: weighing the silicon rubber, the modified conductive filler and the vulcanizing agent according to the formula ratio, stirring and mixing uniformly to obtain a cured raw material, heating the cured raw material to 180-210 ℃, and carrying out heat preservation reaction for 1.5-3 min under the pressure of 5-10 MPa to obtain the conductive silica gel.
9. A silica gel button is characterized in that: the conductive silicone gel of any one of claims 1-7 injection molded by an injection molding process.
Technical Field
The invention relates to the technical field of silica gel products, in particular to conductive silica gel, a preparation method thereof and a silica gel key.
Background
The conductive silica gel belongs to a silica gel product and has certain mechanical property and conductivity. Conductive silica gel is commonly used as a key of an electric appliance. Generally, conductive filler is added into the silica gel raw material, and the silica gel raw material and a vulcanizing agent are subjected to a vulcanization reaction to prepare the conductive silica gel. The conductive fillers are contacted with each other in the conductive silica gel to form a conductive path, thereby obtaining conductivity.
With the development of science and technology, the market demand of conductive silica gel is increasing day by day, so the market puts higher requirements on the conductivity of conductive silica gel, that is, the conductive silica gel develops towards high conductivity.
The material of the conductive filler can be selected from noble metals such as gold and silver, and the noble metals are doped into the silica gel raw material to ensure that the conductive silica gel has better conductivity. However, the conductive silica gel prepared by the method has high cost, and metal particles are easy to migrate on the surface of the silica gel raw material, so that the surface conductivity of the conductive silica gel is reduced and the conductivity is unstable. When carbon black, graphene and the like are used as the conductive filler, the compatibility between the conductive filler and the silica gel raw material is poor, the graphene is easy to agglomerate, and the dispersibility of the conductive filler in the silica gel raw material is poor, so that the conductivity of the conductive silica gel is poor.
Disclosure of Invention
In order to improve the conductivity of the conductive silica gel, the application provides the conductive silica gel, a preparation method thereof and a silica gel key.
In a first aspect, the present application provides a conductive silica gel, which adopts the following technical scheme:
the conductive silica gel is prepared from the following raw materials in parts by weight:
40-60 parts of silicone rubber
3-5 parts of modified conductive filler
0.5-1.5 parts of a vulcanizing agent;
the modified conductive filler is silicon nitride-graphite oxide particles formed by coating silicon carbide with graphene oxide, and the modified conductive filler has a core-shell structure.
The modified conductive filler with the core-shell structure is added into the silicone rubber, and can form better conductive silica gel under the vulcanization effect of the vulcanizing agent. The reason for this is as follows: firstly, compared with the traditional graphene oxide and silicon nitride particles, the modified conductive filler has a core-shell structure, the size of the modified conductive filler is slightly increased, the electrostatic repulsion existing between particles is increased, the surface energy of the modified conductive filler is reduced, agglomeration is not easy to occur, and the modified conductive filler can be stably dispersed in silicon rubber. The modified conductive filler forms a current channel through the contact between graphene oxide on the surface, the contact area between the graphene oxide is moderate, and the volume resistance is small.
Secondly, the silicon rubber is formed into linear macromolecules by the reaction of dimethyl siloxane and an organic silicon monomer, the silicon rubber contains partial unreacted silicon hydroxyl, and because the surface of the modified conductive filler contains hydroxyl, hydrogen bonds are easily formed between the hydroxyl on the surface of the modified conductive filler and the silicon hydroxyl in the silicon rubber, the compatibility of the modified conductive filler and the silicon rubber is better, and the conductivity of the conductive silicon rubber is improved.
In addition, the modified conductive filler forms a better heat conducting network in the conductive silica gel, has higher specific heat capacity, can quickly absorb the heat of the conductive silica gel, and improves the thermal decomposition starting temperature of the conductive silica gel. Meanwhile, due to the full dispersion of the modified conductive filler, the number of crosslinking points between the modified conductive filler and the silicone rubber is increased, and the number of crosslinking points is increased, so that intermolecular force between the conductive silica gels is improved, and the thermal stability of the conductive silica gels is improved.
Further, the modified conductive filler is prepared according to the following steps:
silicon nitride modification treatment: ultrasonically dispersing silicon nitride in a solvent to prepare a silicon nitride suspension, adding an aminosilane coupling agent into the silicon nitride suspension, wherein the weight ratio of the silicon nitride to the aminosilane coupling agent is 1 (0.05-0.15), uniformly mixing to prepare a first reaction solution, heating the first reaction solution to 55-65 ℃, and carrying out heat preservation reaction for 6-10 hours to obtain modified silicon nitride;
preparing a filler: ultrasonically dispersing modified silicon nitride in a solvent to prepare a modified silicon nitride solution, adding a graphene oxide dispersion solution into the modified silicon nitride solution, wherein the weight ratio of silicon nitride to graphene oxide is 1 (0.1-0.2), uniformly mixing to prepare a second reaction solution, heating the second reaction solution to 30-50 ℃, and carrying out heat preservation reaction for 3-4 hours to obtain the modified conductive filler.
And (3) reacting the silicon-oxygen bond of the amino siloxane coupling agent with the silicon hydroxyl on the surface of the silicon nitride, grafting the amino siloxane coupling agent on the silicon nitride, and modifying the silicon nitride to obtain the modified silicon nitride. The amino group of the modified silicon nitride is ionized in an aqueous solution, the modified silicon nitride is positively charged, the carboxyl group and the surface phenolic hydroxyl group of the graphene oxide are ionized in the aqueous solution, the graphene oxide is negatively charged, and the graphene oxide and the modified silicon nitride are subjected to electrostatic self-assembly to form a core-shell coating structure, so that the modified conductive filler is prepared. The preparation method of the conductive filler is simple and environment-friendly.
Further, the weight ratio of the aminosilane coupling agent to the graphene oxide to the silicon nitride is 0.1:0.1: 1.
Further, dilute nitric acid is added into the silicon nitride turbid liquid before aminosilane coupling agent is added in the silicon nitride modification treatment step, and the pH value of the silicon nitride turbid liquid is adjusted to 3-5.
By adopting the technical scheme, the silicon nitride suspension is acidified, and the aminosilane coupling agent is rapidly hydrolyzed within the pH value range, so that silicon hydroxyl is more easily generated, and the modification of silicon nitride is promoted.
Further, the aminosilane coupling agent is one or more of bis- [3- (trimethoxy silicon) -propyl ] -amine, N-dimethyl-3-aminopropyl trimethoxy silane and N- (2-aminoethyl) -3-aminopropyl triethoxy silane.
The bis- [3- (trimethoxy silicon) -propyl ] -amine, N-dimethyl-3-aminopropyl trimethoxy silane and N- (2-aminoethyl) -3-aminopropyl triethoxy silane are polyamino type amino silane coupling agents, the polyamino type amino silane coupling agents improve the ionization capacity of modified silicon nitride in water, promote the subsequent electrostatic self-assembly between graphene oxide and modified silicon nitride, and improve the coating success rate of a core-shell structure.
Further, the silicone rubber is methyl vinyl silicone rubber.
The carbon-carbon double bond contained in the methyl vinyl silicone rubber can perform ring-opening reaction with the epoxy bond on the surface of the modified conductive filler, so that the graphene oxide is partially reduced, the content of epoxy functional groups is reduced, the pi-pi conjugated structure of the graphene conjugated region is increased, and the conductivity of the conductive silica gel is further improved.
Further, the mole fraction of vinyl chain units of the methyl vinyl silicone rubber is 0.03-0.24%.
Vulcanizing agents useful herein include, but are not limited to, dicumyl peroxide (DCP), di-t-butyl peroxide (DTBP).
In a second aspect, the present application provides a method for preparing a conductive silica gel, which adopts the following technical scheme:
a preparation method of conductive silica gel comprises the following steps:
weighing the silicon rubber, the modified conductive filler and the vulcanizing agent according to the formula ratio, stirring and mixing uniformly to obtain a cured raw material, heating the cured raw material to 180-210 ℃, and carrying out heat preservation reaction for 1.5-3 min under the pressure of 5-10 MPa to obtain the conductive silica gel.
The preparation method is simple, the required energy consumption is low, the preparation method is green and environment-friendly, and the conductive silica gel prepared by the preparation process has excellent conductive performance.
In a third aspect, the present application provides a silica gel key, which adopts the following technical scheme:
a silica gel key is formed by injection molding of the conductive silica gel through an injection molding process.
By adopting the technical scheme, the volume resistivity of the silica gel key made of the conductive silica gel is small, the conductivity is good, and the conductive stability is good.
In summary, the present application has the following beneficial effects:
1. the silicon carbide is coated by the graphene oxide to form the modified conductive filler with the silicon nitride-graphite oxide core-shell structure, the modified conductive filler and the silicon rubber have good compatibility, the possibility of agglomeration of the modified conductive filler is low, the modified conductive filler is contacted with the graphene oxide, the contact area between the graphene oxide is moderate, the volume resistance is low, and the conductivity of the conductive silica gel is improved.
2. The modified conductive filler has higher specific heat capacity, forms a better heat conducting network in the conductive silica gel, can quickly absorb the heat of the conductive silica gel, improves the thermal decomposition initial temperature of the conductive silica gel, and improves the thermal stability of the conductive silica gel.
3. The method is simple and environment-friendly in process, and the yield of the product is high.
Detailed Description
The starting materials in the following preparations and examples are derived from table 1 below.
TABLE 1 sources of raw materials
Examples of preparation of modified conductive Filler
Preparation example 1
A modified conductive filler, comprising the following steps:
silicon nitride modification treatment:
weighing 40kg of silicon nitride powder, putting the silicon nitride powder into 300L of absolute ethyl alcohol solution, and performing ultrasonic dispersion at an ultrasonic frequency of 40kHz for 1h to obtain a silicon nitride suspension;
under the condition that the silicon nitride suspension is stirred at the speed of 300r/min, adding deionized water (the volume ratio of the deionized water to the absolute ethyl alcohol is 1:10), and continuously adding 2kg of gamma-aminopropyl triethylsilane to prepare a reaction solution I;
and heating the reaction solution to 55 ℃, keeping the temperature for reaction for 6h, filtering, washing the obtained solid deionized water for 3 times, and freeze-drying to obtain the modified silicon nitride.
Preparing a filler:
putting the modified silicon nitride prepared in the step into 300mL of deionized water, and performing ultrasonic dispersion at the ultrasonic frequency of 40kHz for 1h to prepare a modified silicon nitride solution;
under the condition of mechanical stirring at the speed of 300r/min, 200L of graphene oxide dispersion liquid (the solvent of the dispersion liquid is deionized water) with the concentration of 20mg/mL is added into the modified silicon nitride solution to prepare a second reaction liquid, the second reaction liquid is heated to 30 ℃, the temperature is kept for reaction for 3 hours, standing and filtering are carried out, supernatant is removed, and the obtained solid deionized water is washed for three times and then is frozen and dried to obtain the modified conductive filler.
Preparation examples 2 to 5
The modified conductive filler is different from the preparation example 1 in the weight difference of the silicon nitride, gamma-aminopropyl triethylsilane and graphene oxide dispersion liquid, and the specific input amount is shown in the following table 2.
TABLE 2 weight of silicon nitride, gamma-aminopropyltriethylsilane and graphene oxide
Preparation example
Silicon nitride/kg
Gamma-aminopropyl triethylsilane/kg
Graphene oxide dispersion/L
Preparation example 1
40
2
200
Preparation example 2
40
4
200
Preparation example 3
40
6
200
Preparation example 4
40
4
300
Preparation example 5
40
4
400
Preparation examples 6 to 8
A modified conductive filler, which is different from preparation example 1 in the selection of the aminosilane coupling agent, is specifically selected as shown in table 3 below.
TABLE 3 selection of aminosilane coupling agents
Preparation example 9
A modified conductive filler is different from the preparation example 1 in the operation of the silicon nitride modification treatment step, and the specific operation is as follows:
weighing 40kg of silicon nitride powder, putting the silicon nitride powder into 300mL of absolute ethyl alcohol solution, and performing ultrasonic dispersion at an ultrasonic frequency of 40kHz for 1h to obtain a silicon nitride suspension;
under the condition that the silicon nitride suspension is mechanically stirred at the speed of 300r/min, dilute nitric acid with the concentration of 5 wt% is used for adjusting the silicon nitride suspension to enable the pH value of the silicon nitride suspension to be 4 +/-1, and 4kg of gamma-aminopropyltriethylsilane is continuously added to prepare a first reaction solution;
and heating the reaction solution to 55 ℃, keeping the temperature for reaction for 6h, filtering, washing the obtained solid deionized water for 3 times, and freeze-drying to obtain the modified silicon nitride.
Preparation examples 10 to 11
A modified conductive filler is different from preparation example 1 in the reaction temperature and reaction time in the silicon nitride modification treatment step and the filler preparation step, and specific parameters are shown in Table 4 below.
TABLE 4 reaction temperature and reaction time
Examples
Example 1
A conductive silica gel is prepared by the following steps:
weighing 40kg of alpha, omega-dihydroxy polysiloxane, 3kg of the modified conductive filler prepared in the preparation example 1 and 2kg of vulcanizing agent C-16B-2, and uniformly stirring at the speed of 300r/min to obtain a vulcanizing raw material;
and heating the vulcanization raw material to 180 ℃, and carrying out heat preservation reaction for 1.5min under the pressure of 5MPa to obtain the conductive silica gel.
Examples 2 to 11
A conductive silicone rubber, which is different from example 1 in the source of the modified conductive filler, and the specific source is shown in table 5 below.
TABLE 5 sources of modified conductive fillers
Examples
Source of modified conductive filler
Examples
Source of modified conductive filler
Example 2
Preparation example 2
Example 7
Preparation example 7
Example 3
Preparation example 3
Example 8
Preparation example 8
Example 4
Preparation example 4
Example 9
Preparation example 9
Example 5
Preparation example 5
Example 10
Preparation example 10
Example 6
Preparation example 6
Example 11
Preparation example 11
Examples 12 to 17
A conductive silica gel, which is different from example 5 in the weight of α, ω -dihydroxypolysiloxane, modified conductive filler and vulcanizing agent, as shown in table 6 below.
TABLE 6 weight of alpha, omega-dihydroxy polysiloxane, modified conductive filler and vulcanizing agent
Examples
Alpha, omega-dihydroxypolysiloxanes/kg
Modified conductive filler/kg
Vulcanizing agent/kg
Example 5
40
3
0.5
Example 12
50
3
0.5
Example 13
60
3
0.5
Example 14
50
4
0.5
Example 15
50
5
0.5
Example 16
50
5
1
Example 17
50
5
1.5
Example 18
An electrically conductive silicone rubber which is different from that in example 17 in that an equal mass of methylvinylsiloxane rubber is used in place of the α, ω -dihydroxypolysiloxane, and the mole fraction of vinyl units in the methylvinylsiloxane rubber is 0.03 to 0.12%.
Example 19
An electrically conductive silicone rubber which is different from that in example 17 in that an equal mass of methylvinylsiloxane rubber II is used in place of the α, ω -dihydroxypolysiloxane, and the mole fraction of vinyl units in the methylvinylsiloxane rubber II is 0.13 to 0.18%.
Example 20
An electrically conductive silicone rubber which is different from that in example 17 in that an equal mass of methylvinylsiloxane rubber tris is used in place of the α, ω -dihydroxypolysiloxane, and the mole fraction of vinyl units in the methylvinylsiloxane rubber bis is 0.19 to 0.24%.
Comparative example
Comparative example 1
A conductive silicone gel differs from example 1 in that silicon carbide is used instead of an equivalent mass of modified conductive filler.
Comparative example 2
A conductive silica gel, which is different from the conductive silica gel of example 1 in that a graphene oxide solid is used to replace a modified conductive filler, wherein the weight of the graphene oxide solid is 3kg, and the type of the graphene oxide solid is XF0337440-44-0 and purchased from Nanjing Xiancheng nanotechnology Co.
Comparative example 3
A conductive silica gel, which is different from example 1 in that 1.5kg of silicon carbide and 1.5kg of graphene oxide solid, which is purchased from nanjing piont nanotechnology limited and has a model of XF0337440-44-0, were used in place of 3kg of modified conductive filler.
Performance test
Detection method
The conductive silicone rubbers prepared in examples 1 to 20 and comparative examples 1 to 3 were put into an injection molding machine and injected into a mold to form 100 silicone rubber key samples (size 3 cm. times.2 cm. times.3 cm) of the same size.
Mechanical properties: the tensile strength and elongation at break of the test specimens were carried out according to GB/T528-1998 determination of tensile stress strain Properties of vulcanizates or thermoplastic rubbers;
conductivity: the volume resistivity of the test specimens was determined in accordance with GB/T2439-2001, determination of the resistivity of the conductivity and dissipation properties of vulcanizates or thermoplastic rubbers.
1# detection conditions: volume resistivity measurements were made on samples that were not subjected to the aging test.
2# detection conditions: and (3) placing the silica gel key sample in an aging oven for hot air aging, setting the temperature in the aging oven to be 150 ℃, and performing volume resistivity detection on the silica gel key sample after testing for 120 h.
Yield: and (3) detecting the appearances of 100 silica gel key samples, and determining that the silica gel key samples are unqualified products if any one of dead materials, damage, deflection, dirt and bubbles occurs.
The result of the detection
TABLE 7 data of mechanical property measurements of samples of silicone keys obtained in examples 1 to 20 and comparative examples 1 to 3
Sample (I)
Tensile strength/MPa
Elongation at break/%
Sample (I)
Tensile strength/MPa
Elongation at break/%
Example 1
15.30
205
Example 13
17.25
231
Example 2
15.63
209
Example 14
17.56
235
Example 3
15.96
214
Example 15
17.88
240
Example 4
16.29
218
Example 16
18.19
244
Example 5
16.63
223
Example 17
18.51
248
Example 6
15.72
211
Example 18
18.85
253
Example 7
16.15
216
Example 19
19.18
257
Example 8
16.57
222
Example 20
19.52
262
Example 9
16.90
227
Comparative example 1
10.20
137
Example 10
15.75
211
Comparative example 2
11.10
149
Example 11
16.08
215
Comparative example 3
10.81
154
Example 12
16.94
227
TABLE 8 conductivity of the silica gel key samples obtained in examples 1-20 and comparative examples 1-3
TABLE 9 yields of silicone rubber key samples obtained in examples 1-20 and comparative examples 1-3
Sample (I)
Percent yield/%)
Sample (I)
Percent yield/%)
Example 1
91
Example 13
94
Example 2
91
Example 14
94
Example 3
91
Example 15
95
Example 4
92
Example 16
95
Example 5
92
Example 17
95
Example 6
92
Example 18
95
Example 7
92
Example 19
96
Example 8
93
Example 20
96
Example 9
93
Comparative example 1
80
Example 10
93
Comparative example 2
81
Example 11
94
Comparative example 3
79
Example 12
94
Data analysis
Combining example 1 and comparative examples 1-3 and combining table 7, it can be seen that: the tensile strength of the silica gel key sample prepared in the embodiment 1 is 15.30Mpa, and the elongation at break is 205%, which proves that the mechanical property of the conductive silica gel can be obviously improved by coating the silicon carbide with the graphene oxide, and the modified conductive filler is uniformly dispersed in the conductive silica gel, so that the conductive silica gel has moderate elasticity and good mechanical property.
The volume resistivity reflects the quality of the conductive performance between the conductive silica gels, and the lower the volume resistivity is, the better the conductive performance is. Combining example 1 and comparative examples 1-3 and combining table 8, it can be seen that: the volume resistivity of the silica gel key sample prepared in the example 1 under the detection condition of # 1 is only 59 omega cm, which is much lower than that of the comparative examples 1-3, and thus, the conductive performance of the conductive silica gel can be obviously improved by coating the silicon carbide with the graphene oxide.
After the silica gel key sample is degraded in a high-temperature environment, the conductive network of the silica gel key sample is damaged, and the volume resistivity is increased. Combining example 1 and comparative examples 1 to 3 with table 8, the volume resistivity of the silicone key sample prepared in example 1 increased from 59 Ω · cm to 63 Ω · cm after aging with hot air, while the volume resistivity of the silicone key sample prepared in comparative example 1 increased from 116 Ω · cm to 142 Ω · cm after aging with hot air, the volume resistivity of the silicone key sample prepared in comparative example 2 increased from 106 Ω · cm to 139 Ω · cm after aging with hot air, and the volume resistivity of the silicone key sample prepared in comparative example 3 increased from 109 Ω · cm to 143 Ω · cm after aging with hot air.
The volume resistivity of the comparative examples 1 to 3 is remarkably increased, and the results prove that the silica gel key sample prepared in the example 1 is not easy to degrade in a high-temperature environment and has good thermal stability. The possible reason for the synergistic effect is that the graphene oxide and the silicon nitride have a synergistic effect in the aspect of heat conduction after being modified, so that the modified conductive filler has excellent heat conduction performance, heat absorption and heat release can be quickly realized, the possibility of thermal degradation of the conductive silica gel is reduced, and the stability of the conductive silica gel is improved.
In combination with examples 1-5 and in combination with Table 8, it can be seen that: when the weight ratio of the aminosilane coupling agent to the graphene oxide to the silicon nitride is 0.1:0.1:1, the prepared modified conductive filler has excellent conductivity and good thermal stability, and still has good conductivity after high-temperature aging.
Combining example 1 and examples 6-8 and combining table 8, it can be seen that: the conductive performance of the conductive silica gel can be improved by modifying silicon nitride by using the polyamino aminosilane coupling agent. Meanwhile, when the bis- [3- (trimethoxy silicon) -propyl ] -amine, the N, N-dimethyl-3-aminopropyl trimethoxy silane and the N- (2-aminoethyl) -3-aminopropyl triethoxy silane are compounded for use, the aminosilane coupling agent has the best modification effect on silicon nitride, and the prepared modified conductive filler is doped into silicon rubber, so that the conductive performance of the conductive silica gel is excellent.
Combining example 1 and examples 9-11 and combining table 8, it can be seen that: the coating rate of the modified conductive filler can be increased by increasing the concentration of hydrogen ions in the coating process of the modified silicon nitride and the graphene oxide, so that the conductivity of the conductive silica gel is improved.
Combining example 1 and examples 12-17 and combining table 8, it can be seen that: the addition amount of the modified conductive filler is increased, and the volume resistivity of the conductive silica gel is reduced.
Combining example 1 and examples 18-20 and combining tables 7-8, it can be seen that: the volume resistivity of the conductive silica gel can be reduced by using the methyl vinyl silicone rubber containing carbon-carbon double bonds to prepare the conductive silica gel, so that the methyl vinyl silicone rubber has a certain reduction effect on graphene oxide on the surface of the modified conductive filler, and when the mole fraction of vinyl chain links of the methyl vinyl silicone rubber is 0.03-0.24%, the carbon-carbon double bonds of the methyl vinyl silicone rubber do not influence the stability of the conductive silica gel.
Combining examples 1-20 and comparative examples 1-3 and combining table 9, it can be seen that: the yield of the silica gel key sample is not lower than 85%, and the preparation method is proved to have low difficulty and good yield in preparation of the silica gel key sample.
The present embodiment is only for explaining the present application, and it is not limited to the present application, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present application.