阅读说明：本技术 一种陶瓷化阻燃硅橡胶材料及其制备方法 (Ceramic flame-retardant silicon rubber material and preparation method thereof ) 是由 薛帅伟 刘华夏 周侃 于 2021-08-02 设计创作，主要内容包括：本发明提供一种陶瓷化阻燃硅橡胶材料及其制备方法,该陶瓷化阻燃硅橡胶材料中,三聚氰胺氰尿酸盐、氮化硼@铁酸铋、低熔点玻璃粉与偶联剂的共同作用,使得阻燃硅橡胶在常温下具有良好的弹性和力学性能,而明火或高温状态下,硅橡胶材料会快速变成一种自支撑性的陶瓷体,物理膨胀炭层的致密度和石墨化程度进一步加强,燃烧系统中气相热解产物释放量不断降低的同时,保证了硅橡胶材料良好自熄性、氧指数、弯曲强度和质量损失率。(The invention provides a ceramic flame-retardant silicon rubber material and a preparation method thereof, wherein in the ceramic flame-retardant silicon rubber material, melamine cyanurate, boron nitride @ bismuth ferrite, low-melting-point glass powder and a coupling agent act together, so that the flame-retardant silicon rubber has good elasticity and mechanical properties at normal temperature, and under the open fire or high temperature state, the silicon rubber material can be rapidly changed into a self-supporting ceramic body, the density and graphitization degree of a physical expansion carbon layer are further enhanced, and the release amount of a gas phase pyrolysis product in a combustion system is continuously reduced, and meanwhile, the good self-extinguishing property, oxygen index, bending strength and mass loss rate of the silicon rubber material are ensured.)

1. A ceramic flame-retardant silicone rubber material is characterized in that: the feed comprises the following raw materials in parts by weight: 100 parts of silicone rubber, 15-60 parts of reinforcing filler, 3-12 parts of structural control agent, 5-30 parts of melamine cyanurate, 10-60 parts of boron nitride @ bismuth ferrite, 10-50 parts of fluxing agent, 2-8 parts of peroxide vulcanizing agent, 0.5-8 parts of metal oxide, 0.5-5 parts of stearic acid and 0.5-3 parts of coupling agent.

2. The ceramic flame retardant silicone rubber material as claimed in claim 1, wherein: the melamine cyanurate has a pH of 5.0-7.5, an MCA content of not less than 99.5%, a thermal decomposition temperature of 440-450 ℃, a water solubility of not more than 0.1%, and a particle size of 8-50 μm.

3. The ceramic flame retardant silicone rubber material as claimed in claim 1, wherein: the boron nitride @ bismuth ferrite is formed by coating the surface of the boron nitride with the bismuth ferrite.

4. The ceramicized flame retardant silicone rubber material according to claim 1 or 3, wherein: the preparation method of the boron nitride @ bismuth ferrite comprises the following steps: bi (NO)₃)₃·5H₂O and FeCl₃·6H₂And dissolving and mixing O, adjusting the pH value to be alkaline, dispersing in a boron nitride dispersion liquid, and keeping for 12-20 hours under high pressure to obtain boron nitride @ bismuth ferrite.

5. The ceramic flame retardant silicone rubber material as claimed in claim 1, wherein: the fluxing agent is glass powder, the glass powder is amorphous hard particles, the melting point is 350-500 ℃, and the particle size is 10-45 mu m.

6. The ceramic flame retardant silicone rubber material as claimed in claim 1, wherein: the reinforcing filler is selected from at least one of white carbon black prepared by a precipitation method and white carbon black prepared by a gas phase method.

7. The ceramic flame retardant silicone rubber material as claimed in claim 1, wherein: the structural control agent is selected from at least one of hydroxyl silicone oil, vinyl hydroxyl silicone oil, hexamethyl disilazane and diphenyl silanediol.

8. The ceramic flame retardant silicone rubber material as claimed in claim 1, wherein: the coupling agent is at least one selected from vinyl trimethoxy silane, amino silane, 3-aminopropyl triethoxy silane and epoxy silane coupling agent.

9. The preparation method of the ceramic flame-retardant silicone rubber material according to claims 1 to 8, characterized in that: the method comprises the following steps:

s1: the melamine cyanurate, the boron nitride @ bismuth ferrite and the coupling agent are stirred and mixed to obtain the composite flame retardant;

s2: after the roller is wrapped by the silicon rubber, adding the metal oxide and the stearic acid, and mixing;

s3: adding reinforcing filler, a structural control agent, a fluxing agent and the composite flame retardant in batches, and mixing to obtain a rubber compound;

s4: and mixing the rubber compound with a peroxide vulcanizing agent to obtain a rubber sheet, and vulcanizing the rubber sheet to obtain the ceramic flame-retardant silicone rubber material.

10. The method for preparing the ceramic flame-retardant silicone rubber material according to claim 9, wherein: the stirring and mixing temperature in the S1 is 80-120 ℃, and the time is 30-90 min.

Technical Field

The invention belongs to the technical field of flame-retardant materials, and particularly relates to a ceramic flame-retardant silicon rubber material and a preparation method thereof.

Background

The main chain structure of most natural rubber and synthetic rubber is composed of C-C bonds, while the molecular main chain of the silicon rubber is mainly composed of Si-O structures, and the structure is an inorganic structure, and the side group is alkyl or other elements, and belongs to a semi-inorganic elastomer with saturated main chain, amorphous main chain and non-polarity. Along with unique properties of chemical stability, high and low temperature resistance, weather resistance, insulativity, physical inertia and the like, the silicone rubber is widely applied to the fields of electronic appliances, wires and cables, insulators, automobile accessories and the like.

In the current production life of human beings, the flame retardant and fire resistant performance is one of the performances which almost need to be considered, the silicon rubber is not exceptional, although the oxygen index of the silicon rubber can reach about 26 percent, when the silicon rubber is subjected to high temperature, along with the decomposition and oxidation of organic groups such as methyl, vinyl and the like of a side chain, the silicon-oxygen bond of a main chain and the hydroxyl of the side chain are polymerized again, so that the silicon rubber is gradually oxidized and decomposed into cyclic polymers, and finally SiO is generated under the continuous erosion of high temperature₂The ceramic layer has certain heat insulation and oxygen insulation effects, can insulate the contact between oxygen and combustible materials, reduces the concentration of the oxygen in a combustion system, but has lower strength, is easy to collapse and deform in the combustion process, and greatly reduces the flame retardant efficiency.

The ceramic silicon rubber mainly improves the thermal stability of the silicon rubber through the refractory filler and the sintering aid, if the silicon rubber material does not have the refractory filler and only contains the sintering aid such as low-melting-point glass powder, silicon dioxide powder generated by burning the silicon rubber contains a large number of holes at a high temperature, belongs to a fragile substance and cannot be effectively bonded, and therefore a compact ceramic layer cannot be formed by simply depending on the silicon rubber and the sintering aid. Among the commonly used refractory fillers in ceramic silicone rubber are: white carbon black, mica, wollastonite, kaolin and hexagonal boron nitride. When the layered boron nitride flame retardant is used as a flame retardant, the layered boron nitride can play a physical barrier role on the surface of a combustible material, the temperature and the oxygen content of a combustion system can be reduced, however, the stacking of the layered boron nitride easily causes the occurrence of an agglomeration phenomenon, and the physical and mechanical properties of the silicon rubber material at normal temperature and the strength of a carbon layer at high temperature are greatly influenced.

Disclosure of Invention

The present invention is directed to solving at least one of the problems of the prior art described above. Therefore, the invention provides a ceramic flame-retardant silicone rubber material in a first aspect, which has the characteristics of uniform material dispersion, high compatibility, excellent flame-retardant property and the like, has good elasticity and mechanical properties at normal temperature, and can be quickly converted into a self-supporting ceramic body when in an open fire or high temperature state.

The second aspect of the invention provides a preparation method of the ceramic flame-retardant silicone rubber material.

According to a first aspect of the invention, a ceramic flame-retardant silicone rubber material is provided, which comprises the following raw materials in parts by weight: 100 parts of silicone rubber, 15-60 parts of reinforcing filler, 3-12 parts of structural control agent, 5-30 parts of melamine cyanurate, 10-60 parts of boron nitride @ bismuth ferrite, 10-50 parts of fluxing agent, 2-8 parts of peroxide vulcanizing agent, 0.5-8 parts of metal oxide, 0.5-5 parts of stearic acid and 0.5-3 parts of coupling agent.

In some embodiments of the invention, the silicone rubber is a methyl vinyl silicone rubber; more preferably, the molecular weight of the methyl vinyl silicone rubber is 45-85 ten thousand, the volatile component is less than or equal to 2.0%, the chain link is 10-60%, and the vinyl content is 0.12-0.25. The methyl vinyl silicone rubber with the characteristics can carry a small amount of vinyl, can greatly improve the vulcanization activity of the silicone rubber, improve the physical and mechanical properties of vulcanized rubber, improve the elasticity of rubber materials, reduce the compression permanent deformation, reduce more unstable 'hanging chains' along with the crosslinking of the vinyl at the end, increase the crosslinking density and simultaneously improve the flame retardance.

In some preferred embodiments of the present invention, the melamine cyanurate has a pH of 5.0 to 7.5, an MCA content of 99.5% or more, a thermal decomposition temperature of 440 to 450 ℃, a water solubility of 0.1% or less, and a particle size of 8 to 50 μm. The melamine cyanurate is used as an environment-friendly triazine flame retardant with low production cost, and inert gases decomposed after being heated can be distributed around combustible substances, so that the oxygen concentration of a combustion system is reduced, and the combustion of the material is inhibited. The melamine cyanurate with the characteristic can be rapidly dehydrated into carbon at high temperature, water vapor can take away a part of heat, the carbon is also a flame-retardant substance, and inert gas decomposed after the carbon is heated can be distributed around the combustible substance, so that the oxygen concentration of a combustion system is reduced, and further combustion of the silicon rubber material is inhibited.

In some more preferred embodiments of the present invention, said boron nitride @ bismuth ferrite is such that said boron nitride surface is coated with said bismuth ferrite; further preferably, the particle size of the boron nitride @ bismuth ferrite is 40-300 nm, and the length of the boron nitride @ bismuth ferrite is about 15 nm. In the boron nitride @ bismuth ferrite, bismuth ferrite particles are coated on the surface of boron nitride, so that the boron nitride layers are not easy to stack while the spacing between the boron nitride layers is enlarged, and the dispersibility is better.

According to the invention, the bismuth ferrite has an excellent carbon-promoting effect, and is decomposed by heating to form bismuth oxide and ferric oxide, so that the bismuth ferrite has heat resistance, and after the bismuth ferrite is attached to the surface of boron nitride, the spacing between boron nitride layers can be enlarged, the stacking phenomenon can be reduced, and the dispersibility of the boron nitride can be obviously improved. The melamine cyanurate and the boron nitride @ bismuth ferrite pretreated by the coupling agents such as aminosilane and the like form a composite flame retardant, the finally prepared silicone rubber material is subjected to high temperature, the composite flame retardant, the silicone rubber body and the low-melting-point glass powder act together, the density and the graphitization degree of the physical expansion carbon layer are further enhanced, the release amount of a gas-phase pyrolysis product in a combustion system is continuously reduced, and meanwhile, the good self-extinguishing property, the oxygen index, the bending strength and the mass loss rate of the silicone rubber material are ensured.

In some more preferred embodiments of the present invention, the method for preparing boron nitride @ bismuth ferrite comprises the steps of: bi (NO)₃)₃·5H₂O and FeCl₃·6H₂And dissolving and mixing O, adjusting the pH value to be alkaline, dispersing in a boron nitride dispersion liquid, and keeping for 12-20 hours under high pressure to obtain boron nitride @ bismuth ferrite. The boron nitride @ bismuth ferrite used in the present invention can be prepared by the above-mentioned preparation method,the compound may be obtained according to the methods described in the prior art documents, or may be commercially available.

In some more preferred embodiments of the present invention, the pH is 10 to 14.

In some more preferred embodiments of the present invention, the fluxing agent is glass powder, and the glass powder is amorphous hard particles, has a melting point of 350-500 ℃ and a particle size of 10-45 μm. The low-melting-point glass powder can be melted to form a liquid phase after reaching the softening temperature, flows between the composite flame retardant and the silicon rubber substrate, coats the silicon rubber substrate, is automatically cured after the temperature is reduced, can play a role of a bridge, and increases the strength of the carbon layer.

In some more preferred embodiments of the present invention, the reinforcing filler is selected from at least one of precipitated silica and vapor phase silica.

In some more preferred embodiments of the present invention, the silica includes SiO₂The content is more than or equal to 95 percent, the pH value is 5.0 to 8.0, the content of residues on a sieve with the particle size of 45 mu m is less than or equal to 0.6 percent, and the DBP absorption value is 2.0 to 3.5cm³(ii) in terms of/g. The white carbon black with the characteristic is used as a reinforcing agent in silicon rubber, can improve physical and mechanical properties, and can also be used as a framework material and a ceramic filler of a ceramic body in a ceramic transformation process. With the increase of the consumption of the white carbon black, the fluxing agent and more white carbon black in the matrix are adhered to each other to form a whole, so that the bending strength of the silicon rubber ceramic body is improved.

In some more preferred embodiments of the present invention, the structural control agent is selected from at least one of hydroxy silicone oil, vinyl hydroxy silicone oil, hexamethyldisilazane, and diphenylsilanediol.

In some more preferred embodiments of the present invention, the degree of polymerization of the hydroxy silicone oil is 6 to 10, and the hydroxy content is 6.5 to 8.0%.

In some more preferred embodiments of the present invention, the diphenyl silanediol is white needle-like crystals with a hydroxyl content of 12.5% or more and a melting point of 115 ℃ or more.

In some more preferred embodiments of the invention, the metal oxide is zinc oxide and/or magnesium oxide.

In some more preferred embodiments of the present invention, the coupling agent is at least one selected from the group consisting of vinyltrimethoxysilane, aminosilane, 3-aminopropyltriethoxysilane, epoxysilane coupling agents.

In some more preferred embodiments of the present invention, the peroxide curative is selected from any one of 2, 5-dimethyl-2, 5-bis (t-butylperoxy) hexane (DBPH), dibenzoyl peroxide (BPO), dicumyl peroxide (DCP), and benzoyl Dichloroperoxide (DCBP).

According to a second aspect of the present invention, a method for preparing the above-mentioned ceramic flame-retardant silicone rubber material is provided, which comprises the following steps:

s1: the melamine cyanurate, the boron nitride @ bismuth ferrite and the coupling agent are stirred and mixed to obtain the composite flame retardant;

s2: after the roller is wrapped by the silicon rubber, adding the metal oxide and the stearic acid, and mixing;

s3: adding reinforcing filler, a structural control agent, a fluxing agent and the composite flame retardant in batches, and mixing to obtain a rubber compound;

s4: and mixing the rubber compound with a peroxide vulcanizing agent to obtain a rubber sheet, and vulcanizing the rubber sheet to obtain the ceramic flame-retardant silicone rubber material.

In some embodiments of the present invention, the method for preparing the ceramicized flame retardant silicone rubber material further comprises vacuum drying the raw materials before preparation; further preferably, the temperature of the vacuum drying is 100-120 ℃, and the time is 2-4 h.

In some preferred embodiments of the present invention, the temperature of the stirring and mixing in S1 is 80 to 120 ℃ for 30 to 90 min.

In some more preferred embodiments of the present invention, in the step S2, the silicone rubber is wrapped in a roll by controlling the temperature of the open mill at 35 to 45 ℃, adjusting the roll gap to 2 to 3mm, and adding silicone rubber.

In some more preferred embodiments of the present invention, the mixing time in S2 is 3 to 10 min.

In some more preferred embodiments of the present invention, a reinforcing filler, a structural control agent, a flux and the composite flame retardant are added to S3 3 to 4 times; the interval time is 5-10 min each time.

In some more preferred embodiments of the present invention, the temperature of the vulcanization in S4 is 165 to 175 ℃, the pressure is 10MPa, and the time is 5 to 20 min.

The invention has the beneficial effects that:

1. according to the invention, bismuth ferrite covers the surface of boron nitride, so that the occurrence of a sheet layer stacking phenomenon can be reduced while the spacing of boron nitride layers is increased, and the large specific surface area of boron nitride can realize the dispersion of bismuth ferrite and improve the dispersion of bismuth ferrite in a silicon rubber matrix.

2. In the invention, the bismuth ferrite has excellent catalysis and carbonization promotion effects, and can be decomposed into bismuth oxide and ferric oxide after being combusted under heat, and the component can further enhance the strength of the carbon layer and improve the heat resistance of the silicon rubber material.

3. According to the invention, the flame-retardant silicone rubber prepared by matching the melamine cyanurate, boron nitride and bismuth ferrite composite flame retardant pretreated by the coupling agents such as aminosilane and the like with the low-melting-point glass powder has good elasticity and mechanical properties at normal temperature, and under the open fire or high temperature state, the silicone rubber material can be quickly changed into a self-supporting ceramic body, the density and graphitization degree of the physical expansion carbon layer are further enhanced, and the release amount of gas-phase pyrolysis products in a combustion system is continuously reduced, so that the silicone rubber material is ensured to have good self-extinguishing property, oxygen index, bending strength and mass loss rate.

Detailed Description

The concept and technical effects of the present invention will be clearly and completely described below in conjunction with the embodiments to fully understand the objects, features and effects of the present invention. It is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments, and those skilled in the art can obtain other embodiments without inventive effort based on the embodiments of the present invention, and all embodiments are within the protection scope of the present invention.

Example 1

The embodiment prepares the ceramic flame-retardant silicone rubber, and the specific process comprises the following steps:

the ceramic flame-retardant silicone rubber material comprises the following preparation raw materials in parts by weight: 100 parts of methyl vinyl silicone rubber, 30 parts of fumed silica, 6 parts of hydroxyl silicone oil, 20 parts of melamine cyanurate, 30 parts of boron nitride @ bismuth ferrite, 25 parts of low-melting-point glass powder, 2.0 parts of zinc oxide, 1.0 part of stearic acid, 1.5 parts of vinyl trimethoxy silane and 2.0 parts of DBPH bis-dipentavulcanizing agent. The boron nitride @ bismuth ferrite comprises the following manufacturing raw materials: 600g of Bi (NO)₃)₃·5H₂O, 400g FeCl₃·6H₂O, 30g of hexagonal boron nitride and 10L of NaOH solution (6 mol/L).

In the formula of the ceramic flame-retardant silicone rubber material, the molecular weight of the methyl vinyl silicone rubber is 50 ten thousand, the vinyl content is 0.16 percent, the chain link is 30 percent, and the volatile component is less than or equal to 2.0 percent; the white carbon black SiO by the gas phase method₂The content is more than or equal to 98 percent, the pH value is 6.7, and the content of 45 mu m screen residue is 0.08 percent; the polymerization degree of the hydroxyl silicone oil is 7, and the hydroxyl content is 7.0 percent; the pH value of the melamine cyanurate is 6.5, the MCA content is more than or equal to 99.5 percent, the thermal decomposition temperature is 440-450 ℃, and the particle size is 8 mu m; the melting point of the low-melting-point glass powder is 380-430 ℃, and the particle size is 25 mu m.

The preparation method of the boron nitride @ bismuth ferrite flame retardant comprises the following specific steps:

600g of Bi (NO)₃)₃·5H₂O and 400g FeCl₃·6H₂And respectively dissolving O in deionized water, stirring for 5h at room temperature, adding NaOH to adjust the pH value to 12, adding the mixture into 30g/L boron nitride dispersion liquid to uniformly mix the two, continuously dropwise adding NaOH to stir, keeping the mixture in an autoclave for 15h, fully washing the mixture by using deionized water and ethanol, and drying the mixture for 12h at 60 ℃ to obtain the boron nitride @ bismuth ferrite nano flame retardant.

The preparation method of the ceramic flame-retardant silicone rubber material comprises the following specific steps:

s1: putting the raw material powder into a vacuum drying oven for drying at 105 ℃ for 2 h;

s2: putting melamine cyanurate, boron nitride @ bismuth ferrite and vinyl trimethoxy silane into a stirrer for mixing, wherein the stirring temperature is 90 ℃, and the stirring time is 45min, so as to obtain a composite flame retardant;

s3: controlling the temperature of the open mill at 40 +/-2 ℃, adjusting the roller spacing to 2-3 mm, adding methyl vinyl silicone rubber, after the rubber softens and wraps the roller, adding zinc oxide and stearic acid once, and mixing for 10 min;

s4: adding fumed silica, hydroxyl silicone oil, low-melting-point glass powder and the composite flame retardant obtained in S2 for 3 times, wherein the interval time is 6min each time, continuously mixing for 30min after all the flame retardants are added, and obtaining rubber compound through thin-pass blanking;

s5: placing the rubber compound for 24 hours at room temperature, then placing the rubber compound into an open mill with a roll spacing of 2-3 mm for hot refining and back refining, wrapping the rubber compound with a roll and adding a Bierwu vulcanizing agent when the rubber compound has certain fluidity, fully and uniformly mixing, then packaging a triangular bag for 6 times in a thin-pass state, and increasing the roll spacing and discharging the rubber sheet to obtain a rubber sheet;

s6: and vulcanizing the rubber sheet in a flat vulcanizing machine at the vulcanizing temperature of 170 ℃, the vulcanizing pressure of 10MPa and the vulcanizing time of 8min to obtain the ceramic flame-retardant silicone rubber material.

Example 2

The embodiment prepares the ceramic flame-retardant silicone rubber, and the specific process comprises the following steps:

the ceramic flame-retardant silicone rubber material comprises the following preparation raw materials in parts by weight: 100 parts of methyl vinyl silicone rubber, 40 parts of precipitated white carbon black, 7 parts of vinyl hydroxyl silicone oil, 10 parts of melamine cyanurate, 45 parts of boron nitride @ bismuth ferrite, 28 parts of low-melting-point glass powder, 2.5 parts of magnesium oxide, 1.2 parts of stearic acid, 1.8 parts of aminosilane and 2.3 parts of DBPH bis-dipentavulcanizing agent. The boron nitride @ bismuth ferrite comprises the following manufacturing raw materials: 900g of Bi (NO)₃)₃·5H₂O, 600g FeCl₃·6H₂O, 45g of hexagonal boron nitride and 15L of NaOH solution (6 mol/L).

In the ceramic flame-retardant silicone rubber material, the methyl vinyl silicone rubber is divided intoThe quantum is 60 ten thousand, the vinyl content is 0.18 percent, the chain link is 35 percent, and the volatile content is less than or equal to 2.0 percent; the precipitation method is white carbon black SiO₂The content is more than or equal to 98 percent, the pH value is 6.8, and the content of 45 mu m screen residue is 0.36 percent; the vinyl hydroxyl silicone oil has a hydroxyl mass content of 5%, a viscosity of 30mpa.s and a vinyl mass content of 6%; the pH value of the melamine cyanurate is 6.5, the MCA content is more than or equal to 99.5 percent, the thermal decomposition temperature is 440-450 ℃, and the particle size is 25 mu m; the melting point of the low-melting-point glass powder is 380-430 ℃, and the particle size is 20 mu m.

The preparation method of the boron nitride @ bismuth ferrite flame retardant comprises the following specific steps:

900g of Bi (NO)₃)₃·5H₂O and 600g FeCl₃·6H₂And respectively dissolving O in deionized water, stirring for 5h at room temperature, adding NaOH to adjust the pH value to 12, adding the mixture into 45g/L boron nitride dispersion liquid to uniformly mix the two, continuously dropwise adding NaOH to stir, keeping the mixture in an autoclave for 15h, fully washing the mixture by using deionized water and ethanol, and drying the mixture for 12h at 60 ℃ to obtain the boron nitride @ bismuth ferrite nano flame retardant.

The preparation method of the ceramic flame-retardant silicone rubber material comprises the following specific steps:

s1: putting the raw material powder into a vacuum drying oven for drying at 105 ℃ for 2 h;

s2: putting melamine cyanurate, boron nitride @ bismuth ferrite and aminosilane into a stirrer to be mixed, wherein the stirring temperature is 90 ℃, and the stirring time is 45min, so as to obtain a composite flame retardant;

s3: controlling the temperature of the open mill at 40 +/-2 ℃, adjusting the roller spacing to 2-3 mm, adding methyl vinyl silicone rubber, after the rubber softens and wraps the roller, adding magnesium oxide and stearic acid once, and mixing for 10 min;

s4: adding precipitated white carbon black, vinyl hydroxyl silicone oil, low-melting-point glass powder and the composite flame retardant obtained in S2 for 3 times, wherein the interval time is 6min each time, continuously mixing for 30min after all the materials are added, and obtaining rubber compound through thin-pass blanking;

s5: placing the rubber compound for 24 hours at room temperature, then placing the rubber compound into an open mill with a roll spacing of 2-3 mm for hot refining and back refining, wrapping the rubber compound with a roll and adding a Bierwu vulcanizing agent when the rubber compound has certain fluidity, fully and uniformly mixing, then packaging a triangular bag for 6 times in a thin-pass state, and increasing the roll spacing and discharging the rubber sheet to obtain a rubber sheet;

s6: and vulcanizing the rubber sheet in a flat vulcanizing machine at the vulcanizing temperature of 170 ℃, the vulcanizing pressure of 10MPa and the vulcanizing time of 10min to obtain the ceramic flame-retardant silicone rubber material.

Example 3

The embodiment prepares the ceramic flame-retardant silicone rubber, and the specific process comprises the following steps:

the ceramic flame-retardant silicone rubber material comprises the following preparation raw materials in parts by weight: 100 parts of methyl vinyl silicone rubber, 45 parts of fumed silica, 2 parts of hydroxyl silicone oil, 3.5 parts of diphenyl silanediol, 25 parts of melamine cyanurate, 20 parts of boron nitride @ bismuth ferrite, 35 parts of low-melting-point glass powder, 1.5 parts of zinc oxide, 2.0 parts of magnesium oxide, 2.0 parts of stearic acid, 2.5 parts of 3-aminopropyltriethoxysilane and 2.3 parts of DBPH dipenta-vulcanizing agent. The boron nitride @ bismuth ferrite comprises the following manufacturing raw materials: 400g of Bi (NO)₃)₃·5H₂O, 266g of FeCl₃·6H₂O, 20g of hexagonal boron nitride and 7L of NaOH solution (6 mol/L).

In the ceramic flame-retardant silicone rubber material raw material, the molecular weight of the methyl vinyl silicone rubber is 60 ten thousand, the vinyl content is 0.18%, the chain link is 35, and the volatile component is less than or equal to 2.0%; the white carbon black SiO by the gas phase method₂The content is more than or equal to 98 percent, the pH value is 6.7, and the content of 45 mu m screen residue is 0.08 percent; the polymerization degree of the hydroxyl silicone oil is 7, and the hydroxyl content is 7.0 percent; the hydroxyl content of diphenyl silanediol is 14 percent, and the melting point is 120 ℃; the pH value of the melamine cyanurate is 6.5, the MCA content is more than or equal to 99.5 percent, the thermal decomposition temperature is 440-450 ℃, and the particle size is 50 mu m; the melting point of the low-melting-point glass powder is 380-430 ℃, and the particle size is 35 mu m.

The preparation method of the boron nitride @ bismuth ferrite flame retardant comprises the following specific steps:

400g of Bi (NO)₃)₃·5H₂O and 266g of FeCl₃·6H₂O is respectively dissolved in deionized water, and after stirring for 5 hours at room temperature,adding NaOH to adjust the pH value to 12, adding the mixture into 20g/L boron nitride dispersion liquid to uniformly mix the two, continuously dropwise adding NaOH to stir, keeping the mixture in an autoclave for 15 hours, fully washing the mixture by using deionized water and ethanol, and drying the mixture at 60 ℃ for 12 hours to obtain the boron nitride @ bismuth ferrite nano flame retardant.

The preparation method of the ceramic flame-retardant silicone rubber material comprises the following specific steps:

s1: putting the raw material powder into a vacuum drying oven for drying at 105 ℃ for 2 h;

s2: putting melamine cyanurate, boron nitride @ bismuth ferrite and 3-aminopropyltriethoxysilane into a stirrer for mixing, wherein the stirring temperature is 90 ℃, and the stirring time is 45min, so as to obtain a composite flame retardant;

s3: controlling the temperature of the open mill at 40 +/-2 ℃, adjusting the roller spacing to 2-3 mm, adding methyl vinyl silicone rubber, after the rubber softens and wraps the roller, adding zinc oxide, magnesium oxide and stearic acid once, and mixing for 10 min;

s4: adding fumed silica, hydroxyl silicone oil, diphenyl silanediol, low-melting-point glass powder and the composite flame retardant obtained in S2 for 3 times, wherein the interval time is 6min each time, continuously mixing for 30min after all the materials are added, and obtaining rubber compound through thin-pass blanking;

s5: placing the rubber compound for 24 hours at room temperature, then placing the rubber compound into an open mill with a roll spacing of 2-3 mm for hot refining and back refining, wrapping the rubber compound with a roll and adding a Bierwu vulcanizing agent when the rubber compound has certain fluidity, fully and uniformly mixing, then packaging a triangular bag for 6 times in a thin-pass state, and increasing the roll spacing and discharging the rubber sheet to obtain a rubber sheet;

s6: and vulcanizing the rubber sheet in a flat vulcanizing machine at the vulcanizing temperature of 170 ℃, the vulcanizing pressure of 10MPa and the vulcanizing time of 10min to obtain the ceramic flame-retardant silicone rubber material.

Example 4

The embodiment prepares the ceramic flame-retardant silicone rubber, and the specific process comprises the following steps:

the ceramic flame-retardant silicone rubber material comprises the following preparation raw materials in parts by weight: 100 parts of methyl vinyl silicone rubber and 25 parts of fumed silica30 parts of precipitated silica, 4 parts of vinyl hydroxyl silicone oil, 6 parts of hexamethyldisilazane, 30 parts of melamine cyanurate, 15 parts of boron nitride @ bismuth ferrite, 20 parts of low-melting-point glass powder, 3.0 parts of zinc oxide, 2.0 parts of stearic acid, 1.5 parts of epoxy silane, 1.0 part of vinyl trimethoxy silane and 2.3 parts of DBPH dipentavulcanizing agent. The boron nitride @ bismuth ferrite comprises the following manufacturing raw materials: 300g of Bi (NO)₃)₃·5H₂O, 200g FeCl₃·6H₂O, 15g of hexagonal boron nitride and 5L of NaOH solution (6 mol/L).

In the ceramic flame-retardant silicone rubber material raw material, the molecular weight of the methyl vinyl silicone rubber is 60 ten thousand, the vinyl content is 0.18%, the chain link is 35, and the volatile component is less than or equal to 2.0%; the white carbon black SiO by the gas phase method₂The content is more than or equal to 98 percent, the pH value is 6.7, and the content of 45 mu m screen residue is 0.08 percent; white carbon black SiO by precipitation method₂The content is more than or equal to 98 percent, the pH value is 6.8, and the content of 45 mu m screen residue is 0.36 percent; the vinyl hydroxyl silicone oil has a hydroxyl mass content of 5%, a viscosity of 30mpa.s and a vinyl mass content of 6%; the pH value of the melamine cyanurate is 6.5, the MCA content is more than or equal to 99.5 percent, the thermal decomposition temperature is 440-450 ℃, and the particle size is 15 mu m; the melting point of the low-melting-point glass powder is 380-430 ℃, and the particle size is 35 mu m.

The preparation method of the boron nitride @ bismuth ferrite flame retardant comprises the following specific steps:

300g of Bi (NO)₃)₃·5H₂O and 200g FeCl₃·6H₂And respectively dissolving O in deionized water, stirring for 5h at room temperature, adding NaOH to adjust the pH value to 12, adding the mixture into 15g/L boron nitride dispersion liquid to uniformly mix the two, continuously dropwise adding NaOH to stir, keeping the mixture in an autoclave for 15h, fully washing the mixture by using deionized water and ethanol, and drying the mixture for 12h at 60 ℃ to obtain the boron nitride @ bismuth ferrite nano flame retardant.

The preparation method of the ceramic flame-retardant silicone rubber material comprises the following specific steps:

s1: putting the raw material powder into a vacuum drying oven for drying at 105 ℃ for 2 h;

s2: mixing melamine cyanurate, boron nitride @ bismuth ferrite, epoxy silane and vinyl trimethoxy silane in a stirrer at the stirring temperature of 90 ℃ for 45min to obtain a composite flame retardant;

s3: controlling the temperature of the open mill at 40 +/-2 ℃, adjusting the roller spacing to 2-3 mm, adding methyl vinyl silicone rubber, after the rubber softens and wraps the roller, adding zinc oxide and stearic acid once, and mixing for 10 min;

s4: adding fumed silica, precipitated silica, vinyl hydroxy silicone oil, hexamethyldisilazane, low-melting-point glass powder and the composite flame retardant obtained in S2 for 3 times, wherein the interval time is 6min each time, continuously mixing for 30min after all the silica, and obtaining rubber compound by thin-pass blanking;

s5: placing the rubber compound for 24 hours at room temperature, then placing the rubber compound into an open mill with a roll spacing of 2-3 mm for hot refining and back refining, wrapping the rubber compound with a roll and adding a Bierwu vulcanizing agent when the rubber compound has certain fluidity, fully and uniformly mixing, then packaging a triangular bag for 6 times in a thin-pass state, and increasing the roll spacing and discharging the rubber sheet to obtain a rubber sheet;

s6: and vulcanizing the rubber sheet in a flat vulcanizing machine at the vulcanizing temperature of 170 ℃, the vulcanizing pressure of 10MPa and the vulcanizing time of 10min to obtain the ceramic flame-retardant silicone rubber material.

Comparative example 1

The comparative example prepares a ceramic flame-retardant silicone rubber, and the specific process comprises the following steps:

the ceramic flame-retardant silicone rubber material comprises the following preparation raw materials in parts by weight: 100 parts of methyl vinyl silicone rubber, 30 parts of fumed silica, 6 parts of hydroxyl silicone oil, 2.0 parts of zinc oxide, 1.0 part of stearic acid and 2.0 parts of DBPH bis-dipenta vulcanizing agent.

In the ceramic flame-retardant silicone rubber material raw material, the molecular weight of the methyl vinyl silicone rubber is 50 ten thousand, the vinyl content is 0.16%, the chain link is 30%, and the volatile component is less than or equal to 2.0%; the white carbon black SiO by the gas phase method₂The content is more than or equal to 98 percent, the pH value is 6.7, and the content of 45 mu m screen residue is 0.08 percent; the polymerization degree of the hydroxyl silicone oil is 7, and the hydroxyl content is 7.0%.

The preparation method of the ceramic flame-retardant silicone rubber material comprises the following specific steps:

s1: putting the raw material powder into a vacuum drying oven for drying at 105 ℃ for 2 h;

s2: controlling the temperature of the open mill at 40 +/-2 ℃, adjusting the roller spacing to 2-3 mm, adding methyl vinyl silicone rubber, after the rubber softens and wraps the roller, adding zinc oxide and stearic acid once, and mixing for 10 min;

s3: adding fumed silica and hydroxyl silicone oil for 3 times, wherein the interval time is 6min each time, continuously mixing for 30min after all the fumed silica and the hydroxyl silicone oil are added, and obtaining mixed rubber through thin-pass blanking;

s4: placing the rubber compound for 24 hours at room temperature, then placing the rubber compound into an open mill with a roll spacing of 2-3 mm for hot refining and back refining, wrapping the rubber compound with a roll and adding a Bierwu vulcanizing agent when the rubber compound has certain fluidity, fully and uniformly mixing, then packaging a triangular bag for 6 times in a thin-pass state, and increasing the roll spacing and discharging the rubber sheet to obtain a rubber sheet;

s5: and vulcanizing the rubber sheet in a flat vulcanizing machine at the vulcanizing temperature of 170 ℃, the vulcanizing pressure of 10MPa and the vulcanizing time of 8min to obtain the ceramic flame-retardant silicone rubber material.

Comparative example 2

The comparative example prepares a ceramic flame-retardant silicone rubber, and the specific process comprises the following steps:

the ceramic flame-retardant silicone rubber material comprises the following preparation raw materials in parts by weight: 100 parts of methyl vinyl silicone rubber, 40 parts of precipitated white carbon black, 7 parts of vinyl hydroxyl silicone oil, 28 parts of low-melting-point glass powder, 2.5 parts of magnesium oxide, 1.2 parts of stearic acid, 1.8 parts of aminosilane and 2.3 parts of DBPH double-penta vulcanizing agent.

In the ceramic flame-retardant silicone rubber material raw material, the molecular weight of the methyl vinyl silicone rubber is 60 ten thousand, the vinyl content is 0.18%, the chain link is 35, and the volatile component is less than or equal to 2.0%; the precipitation method is white carbon black SiO₂The content is more than or equal to 98 percent, the pH value is 6.8, and the content of 45 mu m screen residue is 0.36 percent; the vinyl hydroxyl silicone oil has a hydroxyl mass content of 5%, a viscosity of 30mpa.s and a vinyl mass content of 6%; the melting point of the low-melting-point glass powder is 380-430 ℃, and the particle size is 20 mu m.

The preparation method of the ceramic flame-retardant silicone rubber material comprises the following specific steps:

s1: putting the raw material powder into a vacuum drying oven for drying at 105 ℃ for 2 h;

s2: controlling the temperature of the open mill at 40 +/-2 ℃, adjusting the roller spacing to 2-3 mm, adding methyl vinyl silicone rubber, after the rubber softens and wraps the roller, adding magnesium oxide and stearic acid once, and mixing for 10 min;

s3: adding precipitated white carbon black, vinyl hydroxyl silicone oil, low-melting-point glass powder and aminosilane for 3 times, wherein the interval time is 6min each time, continuously mixing for 30min after all the materials are added, and obtaining mixed rubber through thin-pass blanking;

s4: placing the rubber compound for 24 hours at room temperature, then placing the rubber compound into an open mill with a roll spacing of 2-3 mm for hot refining and back refining, wrapping the rubber compound with a roll and adding a Bierwu vulcanizing agent when the rubber compound has certain fluidity, fully and uniformly mixing, then packaging a triangular bag for 6 times in a thin-pass state, and increasing the roll spacing and discharging the rubber sheet to obtain a rubber sheet;

s5: and vulcanizing the rubber sheet in a flat vulcanizing machine at the vulcanizing temperature of 170 ℃, the vulcanizing pressure of 10MPa and the vulcanizing time of 10min to obtain the ceramic flame-retardant silicone rubber material.

Comparative example 3

The comparative example prepares a ceramic flame-retardant silicone rubber, and the specific process comprises the following steps:

the ceramic flame-retardant silicone rubber material comprises the following preparation raw materials in parts by weight: 100 parts of methyl vinyl silicone rubber, 45 parts of fumed silica, 2 parts of hydroxyl silicone oil, 3.5 parts of diphenyl silanediol, 25 parts of melamine cyanurate, 20 parts of boron nitride @ bismuth ferrite, 1.5 parts of zinc oxide, 2.0 parts of magnesium oxide, 2.0 parts of stearic acid, 2.5 parts of 3-aminopropyltriethoxysilane and 2.3 parts of DBPH dipenta-vulcanizing agent. The boron nitride @ bismuth ferrite comprises the following manufacturing raw materials: 400g of Bi (NO)₃)₃·5H₂O, 266g of FeCl₃·6H₂O, 20g of hexagonal boron nitride and 7L of NaOH solution (6 mol/L).

In the ceramic flame-retardant silicone rubber material, the molecular weight of the methyl vinyl silicone rubber is 60 ten thousand, and the vinyl content is 0.18 percentThe chain link is 35 percent, and the volatile content is less than or equal to 2.0 percent; the white carbon black SiO by the gas phase method₂The content is more than or equal to 98 percent, the pH value is 6.7, and the content of 45 mu m screen residue is 0.08 percent; the polymerization degree of the hydroxyl silicone oil is 7, and the hydroxyl content is 7.0 percent; the hydroxyl content of diphenyl silanediol is 14 percent, and the melting point is 120 ℃; the pH value of the melamine cyanurate is 6.5, the MCA content is more than or equal to 99.5 percent, the thermal decomposition temperature is 440-450 ℃, and the particle size is 50 mu m;

the preparation method of the boron nitride @ bismuth ferrite flame retardant comprises the following specific steps: 400g of Bi (NO)₃)₃·5H₂O and 266g of FeCl₃·6H₂And respectively dissolving O in deionized water, stirring for 5h at room temperature, adding NaOH to adjust the pH value to 12, adding the mixture into 20g/L boron nitride dispersion liquid to uniformly mix the two, continuously dropwise adding NaOH to stir, keeping the mixture in an autoclave for 15h, fully washing the mixture by using deionized water and ethanol, and drying the mixture for 12h at 60 ℃ to obtain the boron nitride @ bismuth ferrite nano flame retardant.

The preparation method of the ceramic flame-retardant silicone rubber material comprises the following specific steps:

s1: putting the raw material powder into a vacuum drying oven for drying at 105 ℃ for 2 h;

s2: putting melamine cyanurate, boron nitride @ bismuth ferrite and 3-aminopropyltriethoxysilane into a stirrer for mixing, wherein the stirring temperature is 90 ℃, and the stirring time is 45min, so as to obtain a composite flame retardant;

s3: controlling the temperature of the open mill at 40 +/-2 ℃, adjusting the roller spacing to 2-3 mm, adding methyl vinyl silicone rubber, after the rubber softens and wraps the roller, adding zinc oxide, magnesium oxide and stearic acid once, and mixing for 10 min;

s4: adding the fumed silica, the hydroxyl silicone oil, the diphenylsilanediol and the composite flame retardant obtained in S2 for 3 times, wherein the interval time is 6min each time, continuously mixing for 30min after all the flame retardants are added, and obtaining rubber compound through thin-pass blanking;

s5: placing the rubber compound for 24 hours at room temperature, then placing the rubber compound into an open mill with a roll spacing of 2-3 mm for hot refining and back refining, wrapping the rubber compound with a roll and adding a Bierwu vulcanizing agent when the rubber compound has certain fluidity, fully and uniformly mixing, then packaging a triangular bag for 6 times in a thin-pass state, and increasing the roll spacing and discharging the rubber sheet to obtain a rubber sheet;

s6: and vulcanizing the rubber sheet in a flat vulcanizing machine at the vulcanizing temperature of 170 ℃, the vulcanizing pressure of 10MPa and the vulcanizing time of 10min to obtain the ceramic flame-retardant silicone rubber material.

Comparative example 4

The comparative example prepares a ceramic flame-retardant silicone rubber, and the specific process comprises the following steps:

the ceramic flame-retardant silicone rubber material comprises the following preparation raw materials in parts by weight: 100 parts of methyl vinyl silicone rubber, 25 parts of fumed silica, 30 parts of precipitated silica, 4 parts of vinyl hydroxy silicone oil, 6 parts of hexamethyldisilazane, 30 parts of melamine cyanurate, 15 parts of hexagonal boron nitride, 20 parts of low-melting-point glass powder, 3.0 parts of zinc oxide, 2.0 parts of stearic acid, 1.5 parts of epoxy silane, 1.0 part of vinyl trimethoxy silane and 2.3 parts of DBPH bis-dipenta vulcanizing agent.

In the ceramic flame-retardant silicone rubber material raw material, the molecular weight of the methyl vinyl silicone rubber is 60 ten thousand, the vinyl content is 0.18%, the chain link is 35, and the volatile component is less than or equal to 2.0%; the white carbon black SiO by the gas phase method₂The content is more than or equal to 98 percent, the pH value is 6.7, and the content of 45 mu m screen residue is 0.08 percent; white carbon black SiO by precipitation method₂The content is more than or equal to 98 percent, the pH value is 6.8, and the content of 45 mu m screen residue is 0.36 percent; the vinyl hydroxyl silicone oil has a hydroxyl mass content of 5%, a viscosity of 30mpa.s and a vinyl mass content of 6%; the pH value of the melamine cyanurate is 6.5, the MCA content is more than or equal to 99.5 percent, the thermal decomposition temperature is 440-450 ℃, and the particle size is 15 mu m; the hexagonal boron nitride is white powder, the content of the boron nitride is more than or equal to 98 percent, and the particle size is 30 mu m; the melting point of the low-melting-point glass powder is 380-430 ℃, and the particle size is 35 mu m.

The preparation method of the ceramic flame-retardant silicone rubber material comprises the following specific steps:

s1: putting the raw material powder into a vacuum drying oven for drying at 105 ℃ for 2 h;

s2: mixing melamine cyanurate, hexagonal boron nitride, epoxy silane and vinyl trimethoxy silane in a stirrer at 90 deg.C for 45min to obtain composite flame retardant;

s3: controlling the temperature of the open mill at 40 +/-2 ℃, adjusting the roller spacing to 2-3 mm, adding methyl vinyl silicone rubber, after the rubber softens and wraps the roller, adding zinc oxide and stearic acid once, and mixing for 10 min;

s4: adding fumed silica, precipitated silica, vinyl hydroxy silicone oil, hexamethyldisilazane, low-melting-point glass powder and the composite flame retardant obtained in S2 for 3 times, wherein the interval time is 6min each time, continuously mixing for 30min after all the silica, and obtaining rubber compound by thin-pass blanking;

s5: placing the rubber compound for 24 hours at room temperature, then placing the rubber compound into an open mill with a roll spacing of 2-3 mm for hot refining and back refining, wrapping the rubber compound with a roll and adding a Bierwu vulcanizing agent when the rubber compound has certain fluidity, fully and uniformly mixing, then packaging a triangular bag for 6 times in a thin-pass state, and increasing the roll spacing and discharging the rubber sheet to obtain a rubber sheet;

s6: and vulcanizing the rubber sheet in a flat vulcanizing machine at the vulcanizing temperature of 170 ℃, the vulcanizing pressure of 10MPa and the vulcanizing time of 10min to obtain the ceramic flame-retardant silicone rubber material.

Test examples

Formation tests were performed on the ceramicized flame-retardant silicone rubber materials prepared in examples 1 to 4 and comparative examples 1 to 4, and the results are shown in table 1:

TABLE 1

As can be seen from Table 1, compared with comparative examples 1 to 4, the ceramic flame-retardant silicone rubber materials prepared in examples 1 to 4 have good physical and mechanical properties and flame-retardant properties, wherein the tearing strength B can reach 16.7KN/m, the self-extinguishing property (3.0mm) reaches V-0 grade, and the bending strength can reach 18.3 MPa. Therefore, the performance of the ceramic flame-retardant silicon rubber material prepared by the combined action of the melamine cyanurate, the boron nitride @ bismuth ferrite, the low-melting-point glass powder and the coupling agent is excellent.

Specifically, bismuth ferrite is attached to the surface of boron nitride, the spacing between boron nitride layers is enlarged, the boron nitride layers are not easy to stack, the dispersibility is better, and the compatibility of the boron nitride layers and silicon rubber is further improved along with the pretreatment of coupling agents such as aminosilane and the like on all flame retardants, so that the silicon rubber material has good physical and mechanical properties such as tensile strength and the like at normal temperature.

When the ambient temperature gradually rises, the inert gas decomposed by the melamine cyanurate can be distributed around the combustible, so that the oxygen concentration of the combustion system is reduced, and the combustion of the material is inhibited. Along with the excellent carbon-promoting effect of bismuth ferrite, the bismuth ferrite is decomposed by heating to form bismuth oxide and ferric oxide, so that the bismuth ferrite is attached to the surface of boron nitride, and then a firm physical expansion carbon layer is formed on the surface of a combustible together through pretreatment of a coupling agent such as aminosilane and the like. The low melting point glass powder can be melted to form a liquid phase after reaching the softening temperature, the liquid phase permeates into gaps among ablation residue particles, the residues are bonded into a whole, the silicon rubber matrix is decomposed to generate volatile micromolecular cyclosiloxane and holes caused by the volatile micromolecular cyclosiloxane are filled, the compaction degree of the ceramic body obtained by ablation is improved, the ceramic body is automatically solidified after the temperature is reduced, the bridge effect can be played, the strength of a carbon layer is further increased, the release amount of a gas phase pyrolysis product in a combustion system is continuously reduced, and the silicon rubber material shows good self-extinguishing property, oxygen index, bending strength and mass loss rate.

The embodiments of the present invention have been described in detail, but the present invention is not limited to the embodiments, and various changes can be made without departing from the gist of the present invention within the knowledge of those skilled in the art. Furthermore, the embodiments of the present invention and the features of the embodiments may be combined with each other without conflict.