Modified silicon dioxide flame-retardant composite material as well as preparation method and application thereof in electrical equipment

Abstract

The invention discloses a modified silicon dioxide flame-retardant composite material, a preparation method thereof and application of the modified silicon dioxide flame-retardant composite material in electrical equipment, the preparation method comprises the following steps: silane hydrolysate and silicon dioxide are mixed for a reflux condensation reaction, the temperature of the reflux condensation reaction is 50-70 DEG C, the time of the reflux condensation reaction is 60-75 min, and modified silicon dioxide is obtained; and mixing the modified silicon dioxide, epoxy resin and a curing agent to obtain the modified silicon dioxide flame-retardant composite material. The modified silicon dioxide flame-retardant composite material has the advantages of being low in heat release rate, small in total heat release amount, capable of inhibiting smoke generation and the like, is widely applied to the fields with strict flame retardance requirements such as charging facilities and electronic equipment fireproof packaging, and provides an efficient and reliable solution for meeting the fireproof safety requirements of electrical equipment.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of inorganic powder surface modification, and particularly relates to a modified silica flame-retardant composite material, a preparation method thereof and application in electrical equipment. BACKGROUND

[0002] With the increasing requirements of public safety and environmental protection, developing efficient, halogen-free and environmentally friendly flame-retardant materials has become a key problem that the industry needs to solve. Nano-silica is considered as one of the ideal choices to replace traditional halogen and phosphorus flame retardants due to its high thermal stability, non-toxicity and the ability to form a dense physical barrier during combustion. Silica-based composite flame-retardant materials show broad application prospects in electric vehicle charging facilities, electronic device fireproof packaging and other fields.

[0003] However, nano-silica has poor interfacial compatibility with the epoxy resin matrix, and is prone to agglomeration due to the action of surface hydroxyl groups, which leads to uneven dispersion in the matrix material. This defect directly restricts the full play of the flame-retardant properties of the composite material. Specifically, during the combustion process, the agglomerated silica particles cannot effectively build a continuous and stable carbon layer barrier, resulting in high heat release rate and total heat release of the material. Meanwhile, through cone calorimetry, it can be clearly observed that the peak value of the heat release rate curve of such composite materials is high, the rate of rise is fast, the total heat release is large, and the total smoke generation is significant, indicating that the fire risk is high and the flame-retardant efficiency is not ideal.

[0004] Currently, silane coupling agents are commonly used to modify the surface of nano-silica to improve its dispersibility, but the existing modification methods still cannot fundamentally solve the problem of particle agglomeration, resulting in limited improvement in heat release parameters and insignificant increase in limiting oxygen index of the composite material in the combustion test, making it difficult to pass the strict vertical burning level evaluation.

[0005] Therefore, there is an urgent need in the art for an optimized preparation method for silica / epoxy resin systems to obtain high-performance flame-retardant composite materials with low heat release rate, small total heat release and smoke suppression. SUMMARY

[0006] The technical problem to be solved by the present application is to overcome the shortcomings of the prior art and provide a modified silica flame-retardant composite material with low heat release rate, small total heat release and smoke suppression, as well as a preparation method thereof and application in electrical equipment.

[0007] To solve the above technical problems, the following technical solutions are adopted.

[0008] A preparation method of a modified silica flame-retardant composite material, comprising the following steps: S1, mixing a silane coupling agent and an ethanol aqueous solution to obtain a silane hydrolysis solution; S2, mixing the silane hydrolysis solution obtained in step S1 and the silicon dioxide, and performing a condensation reflux reaction to obtain modified silicon dioxide; the condensation reflux reaction is performed at a temperature of 50-70 DEG C and for a time of 60-75 min; S3, mixing the modified silicon dioxide obtained in step S2 and an epoxy resin, and adding a curing agent to obtain a modified silicon dioxide flame-retardant composite material.

[0009] In the above preparation method, further improvement is that in step S2, the condensation reflux reaction is performed at a temperature of 70 DEG C and for a time of 60 min.

[0010] In the above preparation method, further improvement is that in step S2, the ratio of the silicon dioxide to the silane coupling agent in step S1 is 5 g:20-30 mL.

[0011] In the above preparation method, further improvement is that in step S3, the mass ratio of the epoxy resin to the modified silicon dioxide is 10-20:1, and the mass ratio of the epoxy resin to the curing agent is 2:1.

[0012] In the above preparation method, further improvement is that in step S1, the volume ratio of the silane coupling agent to the aqueous ethanol solution is 1:7-9, the volume ratio of ethanol to water in the aqueous ethanol solution is 3-4:1, and the silane coupling agent is 3-aminopropyltriethoxysilane.

[0013] In the above preparation method, further improvement is that in step S1, the mixing is performed under stirring, and the stirring time is 30 min.

[0014] In the above preparation method, further improvement is that in step S2, the particle size of the silicon dioxide is 100-500 nm, and the silicon dioxide is pretreated before use by drying the silicon dioxide at a temperature of 100 DEG C for a time of 2 h; after the condensation reflux reaction, the reaction product is further treated by vacuum filtration, washing, drying and grinding.

[0015] In the above preparation method, further improvement is that in step S3, the mixing is performed at a temperature of 70 DEG C, and the mixing is performed under stirring for a time of 30 min; the epoxy resin is E-51 epoxy resin, and the curing agent is CH10-C5 curing agent.

[0016] As a general technical concept, the application also provides a modified silicon dioxide flame-retardant composite material prepared by the above preparation method.

[0017] As a general technical concept, the present application also provides an application of the modified silica flame-retardant composite material in electrical equipment.

[0018] Compared with the prior art, the present application has the advantages that: The present application provides a preparation method of a modified silica flame-retardant composite material, wherein a silane hydrolysis solution and silica are mixed for condensation reflux reaction, the temperature of the condensation reflux reaction is 50-70℃, and the time is 60-75 min, to obtain modified silica; the modified silica, epoxy resin and curing agent are mixed to obtain the modified silica flame-retardant composite material. The preparation method of the present application modifies the silica by precisely controlling the process of the condensation reflux reaction, fundamentally solves the problem of poor interfacial compatibility between the silica and the epoxy resin matrix, greatly improves the dispersibility of the silica in the epoxy resin matrix, ensures that the silica can effectively migrate and form a dense barrier layer when the composite material is on fire, and greatly improves the flame-retardant efficiency of the composite material. The modified silica flame-retardant composite material prepared by the present application can fully play its physical barrier role when encountering fire, effectively controls the heat release rate (HRR), total heat release (THR) and total cumulative smoke generation per unit sample area (TSR) of the composite material, has the advantages of low heat release rate, small total heat release and smoke generation inhibition, etc. The preparation method of the present application has simple process operation, can be completed in conventional laboratory equipment, has mild reaction conditions, avoids the problems of energy consumption and side reactions caused by high temperature and long time reaction, and has good process adaptability. The modified silica flame-retardant composite material of the present application is widely applicable to fields with strict requirements on flame retardancy, such as fireproof packaging of charging facilities and electronic equipment, and provides an efficient and reliable solution for solving the fire safety requirements of electrical equipment. BRIEF DESCRIPTION OF DRAWINGS

[0019] Fig. 1 The heat release rate curve of the modified silica flame-retardant composite material in Example 1-Example 2 of the present application and the modified silica flame-retardant composite material in Comparative Example 1-Comparative Example 4.

[0020] Fig. 2 The total heat release curve of the modified silica flame-retardant composite material in Example 1-Example 2 of the present application and the modified silica flame-retardant composite material in Comparative Example 1-Comparative Example 4.

[0021] Fig. 3 The total cumulative smoke generation per unit sample area curve of the modified silica flame-retardant composite material in Example 1-Example 2 of the present application and the modified silica flame-retardant composite material in Comparative Example 1-Comparative Example 4. DETAILED DESCRIPTION

[0022] The present application is further described in conjunction with the accompanying drawings and specific preferred embodiments described below, but the scope of the present application is not limited thereby. The materials and instruments used in the following examples are commercially available.

[0023] Example 1 A method for preparing a modified silica flame-retardant composite material of the present application comprises the following steps: (1) Raw material preparation and pretreatment: Prepare hydrophilic silica powder with a particle size of 500 nm as a raw material, the silica powder particles are spherical, and the silica powder is placed in a 100°C oven for drying for 2 hours to remove adsorbed water, to obtain pretreated silica, for standby. According to the volume ratio of anhydrous ethanol to deionized water of 3:1, mix anhydrous ethanol and deionized water to obtain an ethanol aqueous solution.

[0024] (2) Preparation of silane hydrolysis solution: Take 200 mL of the above ethanol aqueous solution in a 500 mL beaker, add 25 mL of 3-aminopropyl triethoxysilane (KH550), and place the beaker on a magnetic stirrer with a stirring speed of 500 rpm for 30 minutes to hydrolyze KH550 sufficiently to form a uniform and transparent silane hydrolysis solution.

[0025] (3) Modification reaction: Slowly add 5 g of the pretreated silica obtained in step (1) to the silane hydrolysis solution obtained in step (2) to obtain a mixed solution; transfer the mixed solution to a three-necked flask equipped with a condensation reflux device, place the three-necked flask in a magnetic stirrer, and adjust the stirring speed of the magnetic stirrer to 400 rpm for condensation reflux reaction, i.e. at 70°C for 60 min. After the reaction is completed, the reaction product is naturally cooled to room temperature, vacuum filtration is performed, and the filter cake is washed repeatedly with anhydrous ethanol for 3 times to remove physically adsorbed coupling agent and by-products. Place the washed filter cake in a vacuum drying oven at 80°C for 12 hours, grind the dried block-shaped product in a mortar to obtain modified silica.

[0026] (4) Composite material preparation: Heat E-51 epoxy resin to 70°C to reduce the viscosity, mix E-51 epoxy resin and modified silica obtained in step (3) according to the mass ratio of E-51 epoxy resin to modified silica of 10:1, and use a mechanical stirrer to stir at a speed of 600 rpm for 30 minutes to mix them uniformly; add CH10-C5 fast type epoxy curing agent according to the mass ratio of E-51 epoxy resin to CH10-C5 fast type epoxy curing agent of 2:1, and pour into a 150x76x30 mm soft rubber mold after stirring uniformly, stand for 60 minutes to shape and demold, to obtain a modified silica flame-retardant composite material.

[0027] Example 2 A modified silica flame-retardant composite of the present application, the preparation method of which is basically the same as that of the modified silica flame-retardant composite in Example 1, with the only difference being that in step (3), the time of the condensation reflux reaction is 75 min.

[0028] Comparative Example 1 A modified silica flame-retardant composite, the preparation method of which is basically the same as that of the modified silica flame-retardant composite in Example 1, with the only difference being that in step (3), the time of the condensation reflux reaction is 30 min.

[0029] Comparative Example 2 A modified silica flame-retardant composite, the preparation method of which is basically the same as that of the modified silica flame-retardant composite in Example 1, with the only difference being that in step (3), the time of the condensation reflux reaction is 45 min.

[0030] Comparative Example 3 A modified silica flame-retardant composite, the preparation method of which is basically the same as that of the modified silica flame-retardant composite in Example 1, with the only difference being that in step (3), the time of the condensation reflux reaction is 90 min.

[0031] Comparative Example 4 A modified silica flame-retardant composite, the preparation method of which is basically the same as that of the modified silica flame-retardant composite in Example 1, with the only difference being that in step (3), the time of the condensation reflux reaction is 120 min.

[0032] The modified silica flame-retardant composites prepared in Example 1-Example 2 and Comparative Example 1-Comparative Example 4 were subjected to a cone calorimetry test (thermal radiation power 50 kW / m 2 ), and the main flame-retardant parameters, i.e. heat release rate, total heat release amount and cumulative total smoke amount per unit sample area, were measured. Figs. 1-3 In the table, “60 min” represents Example 1, “75 min” represents Example 2, “30 min” represents Comparative Example 1, “45 min” represents Comparative Example 2, “90 min” represents Comparative Example 3 and “120 min” represents Comparative Example 4.

[0033] Fig. 1 The heat release rate curves of the modified silica flame-retardant composites in Example 1-Example 2 and Comparative Example 1-Comparative Example 4 are shown in the following figures. Fig. 1 It can be seen that the curve slope of the modified silica flame-retardant composite in Example 1 is the smallest (reaction time 60 min), i.e. the speed of heat release is the slowest.

[0034] Fig. 2 The total heat release amount curve of the modified silica flame-retardant composite material in the present application embodiment 1 to embodiment 2 and the modified silica flame-retardant composite material in the comparative example 1 to comparative example 4 is shown in the following figure. Fig. 2 It can be seen that the THR of the modified silica flame-retardant composite material in the comparative example 2, i.e. the 45 min modified sample, is the highest, indicating that insufficient modification leads to poor interface combination and the lowest flame-retardant efficiency; as the modification time is prolonged to 60 min and 75 min, the interface compatibility of the system is improved and the carbon layer is more stable, and the THR is obviously reduced; the THR of the modified silica flame-retardant composite material in the comparative example 3, i.e. the 90 min modified sample, is increased. Overall, the total heat release amount curve slope of the 60 min and 75 min modified samples is small, and the total heat release amount is maximally inhibited.

[0035] Fig. 3 The cumulative total smoke amount per unit sample area curve of the modified silica flame-retardant composite material in the present application embodiment 1 to embodiment 2 and the modified silica flame-retardant composite material in the comparative example 1 to comparative example 4 is shown in the following figure. Fig. 3 It can be seen that the TSR value of the modified silica flame-retardant composite material in the comparative example 2, i.e. the 45 min modified sample, is the highest and the smoke suppression performance is the worst; as the time is prolonged to 60 to 75 min, the modification reaction is more sufficient, the interface compatibility of the silica powder and the epoxy resin matrix is improved, and the smoke amount is obviously reduced; the smoke amount of the modified silica flame-retardant composite material in the comparative example 3, i.e. the 90 min modified sample, is increased again due to the over-condensation or agglomeration of the silane coupling agent. Overall, the cumulative total smoke amount of the modified silica flame-retardant composite material in the present application embodiment 1 and embodiment 2, i.e. the 60 min and 75 min modified samples, is the lowest, and the smoke suppression effect is the best.

[0036] The above is only the preferred embodiment of the present application, and does not limit the present application in any form. Although the present application has been disclosed as above with the preferred embodiment, it is not intended to limit the present application. Any person skilled in the art can make many possible changes and modifications to the technical solution of the present application, or modify it into equivalent embodiments with equivalent changes, without departing from the spirit and technical solution of the present application. Therefore, any simple modification, equivalent replacement, equivalent change and modification of the above embodiments according to the technical essence of the present application, which does not depart from the technical solution of the present application, still belongs to the protection scope of the technical solution of the present application.

Claims

1. A process for the preparation of a modified silica flame retardant composite material, characterized in that, The method comprises the following steps: S1, mixing silane coupling agent and ethanol aqueous solution to obtain silane hydrolysis solution; S2, mixing the silane hydrolysis solution obtained in step S1 and silica, and performing condensation reflux reaction to obtain modified silica; the condensation reflux reaction is performed at a temperature of 50-70 DEG C for 60-75 min; S3, mixing the modified silica obtained in step S2 and epoxy resin, and adding curing agent to obtain modified silica flame-retardant composite material.

2. The process for the preparation of a modified silica flame retardant composite according to claim 1, characterized in that, In step S2, the condensation reflux reaction is performed at a temperature of 70 DEG C for 60 min.

3. The process for the preparation of a modified silica flame retardant composite according to claim 2, characterized in that, In step S2, the ratio of silica to silane coupling agent in step S1 is 5 g:20-30 mL.

4. The process for the preparation of a modified silica flame retardant composite according to claim 3, characterized in that, In step S3, the mass ratio of epoxy resin to modified silica is 10-20:1, and the mass ratio of epoxy resin to curing agent is 2:

1.

5. Process for the preparation of a modified silica flame retardant composite according to any one of claims 1 to 4, characterized in that, In step S1, the volume ratio of silane coupling agent to ethanol aqueous solution is 1:7-9, the volume ratio of ethanol to water in the ethanol aqueous solution is 3-4:1, and the silane coupling agent is 3-aminopropyl triethoxysilane.

6. Process for the preparation of a modified silica flame retardant composite according to any one of claims 1 to 4, characterized in that, In step S1, the mixing is performed under stirring for 30 min.

7. Process for the preparation of a modified silica flame retardant composite according to any one of claims 1 to 4, characterized in that, In step S2, the particle size of silica is 100-500 nm, and the silica is pretreated before use by drying at a temperature of 100 DEG C for 2 h; after the condensation reflux reaction, the reaction product is further treated by vacuum filtration, washing, drying and grinding.

8. Process for the preparation of a modified silica flame retardant composite according to any one of claims 1 to 4, characterized in that, In step S3, the mixing is performed at a temperature of 70 DEG C under stirring for 30 min, the epoxy resin is E-51 epoxy resin, and the curing agent is CH10-C5 curing agent.

9. Modified silica flame-retardant composite material prepared by the method of any one of claims 1-8.

10. Application of the modified silica flame-retardant composite material of claim 9 in electrical equipment.

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