CN115521620A - Preparation method of low-additive-amount physical-chemical synergistic flame-retardant silicone rubber - Google Patents

Preparation method of low-additive-amount physical-chemical synergistic flame-retardant silicone rubber Download PDF

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CN115521620A
CN115521620A CN202211036944.5A CN202211036944A CN115521620A CN 115521620 A CN115521620 A CN 115521620A CN 202211036944 A CN202211036944 A CN 202211036944A CN 115521620 A CN115521620 A CN 115521620A
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flame retardant
silicone rubber
retardant
halogen
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郑再航
柴威鸿
苏鑫莹
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Changchun University of Technology
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Abstract

The patent designs and prepares a physical-chemical synergistic flame-retardant silicone rubber with low addition amount. In order to improve the flame retardant efficiency of the flame retardant, expandable graphite with a physical expansion flame retardant effect and melamine polyphosphate loaded by layered hydroxide are mixed according to a certain proportion, a physical-chemical synergistic flame retardant system with a low addition amount is constructed for preparing the flame retardant silicone rubber composite material, and the synergistic char formation effect of the two flame retardant systems and the influence of the addition of the flame retardant on the mechanical property of the silicone rubber composite material are further explored; the implementation of the patent provides a new idea for the development of a halogen-free flame retardant system with low addition amount, cleanness and high efficiency, and also provides an experimental basis for researching the influence of the layered hydroxide on the intumescent flame retardant.

Description

Preparation method of low-additive-amount physical-chemical synergistic flame-retardant silicone rubber
Technical Field
The invention belongs to the technical field of flame-retardant materials, and particularly relates to a preparation method of low-addition-amount physical-chemical synergistic flame-retardant silicone rubber.
Technical Field
Silicone Rubber (SR) is widely used in biomedical, aerospace, electrical and electronic applications due to its light weight, excellent thermal stability, high insulation properties, high or low temperature resistance, and excellent chemical resistance, such as: high voltage transmission lines, bushings and outer insulation of cables. However, silicone rubber materials are inherently flammable, have Low Oxygen Index (LOI) values, and combustion is accompanied by a droplet phenomenon and release of a large amount of smoke and particulate matter, which greatly affects the safety of lives and properties and environmental pollution. The flammability of the silicone rubber severely limits the further application of the silicone rubber in more fields with high performance requirements, so how to obtain the high-performance flame-retardant silicone rubber material becomes a key problem to be solved urgently in the material field.
As a new environment-friendly nano flame retardant with a layered crystal structure, layered hydroxide (LDH) has received increasing attention in recent years in halogen-free flame retardant polymer systems. Layered hydroxides are a class of layered compounds consisting of positively charged mixed metal hydroxide layers with interlayer regions containing charge-compensating anions and water molecules. During the combustion process, the layered hydroxides may not only be released by liberating H 2 The oxygen and the combustible gas are diluted by the oxygen, and the oxygen and the combustible gas can also be used as a physical barrier for isolating flame and absorbing smoke particles, so that the layered hydroxide can effectively improve the flame-retardant efficiency and the smoke suppression performance of the substrate.
Traditionally, there are two methods of preparing flame-retardant silicone rubber: firstly, the structure of a silicon rubber molecular chain is changed by introducing flame-retardant elements. Secondly, a flame retardant is added to the silicone rubber by a physical blending method. In fact, the latter shows greater advantages in industry due to its simple preparation process and wide sources. Halogen-free intumescent flame retardant systems are the hot research in the field of flame retardancy in recent years. Generally, halogen-free intumescent flame retardant systems are largely divided into two categories, physical intumescent flame retardants and chemical intumescent flame retardants. Expandable Graphite (EG) is a novel physically intumescent flame retardant that has been used in many flame retardant applications due to its non-toxicity, abundant raw materials, simple preparation process, low smoke yield, and other advantages; the expandable graphite can form a worm-like structure in the combustion process, and the thin sheets can be used as a protective layer of a polymer matrix and play a role in blocking heat and mass transfer in the combustion process; thus, the addition of expandable graphite to polymeric materials can delay the ignition time by limiting heat and mass transfer from the substrate to the heat source, thereby effectively choking the flame and preventing further decomposition. The chemical intumescent flame retardant mainly comprises a carbon source, an acid source and a gas source, wherein the acid source is heated and decomposed to generate acid with strong dehydration effect, the carbon source is dehydrated and carbonized, the ammonia gas decomposed by the gas source expands the carbon layer to finally form a microporous carbon layer, so that air and heat conduction are isolated, and the purpose of flame retardance is achieved. Most of the traditional methods for flame-retardant silicone rubber materials only add a single intumescent flame retardant, which enables the defects of physical intumescent flame retardance and chemical intumescent flame retardance to be exposed. For example, expandable graphite alone may expand excessively when heated, resulting in a loose, insufficiently dense carbon layer; the flame retarding efficiency of the chemical intumescent flame retardant alone is too low, etc. Therefore, how to improve the efficiency of the halogen-free intumescent flame-retardant silicone rubber material becomes a bottleneck problem.
The patent aims at efficiently improving the flame retardant property of the silicon rubber material, and designs and prepares the physical-chemical synergistic flame retardant silicon rubber with low addition. In order to improve the flame retardant efficiency of the flame retardant, expandable graphite with a physical expansion flame retardant effect and melamine polyphosphate loaded by layered hydroxide are mixed according to a certain proportion, a physical-chemical synergistic flame retardant system with a low addition amount is constructed for preparing the flame retardant silicone rubber composite material, and the synergistic char formation effect of the two flame retardant systems and the influence of the addition of the flame retardant on the mechanical property of the silicone rubber composite material are further explored; the implementation of the patent provides a new idea for the development of a halogen-free flame retardant system with low addition amount, cleanness and high efficiency, and also provides an experimental basis for researching the influence of the layered hydroxide on the intumescent flame retardant.
Disclosure of Invention
The invention particularly relates to a preparation method of low-additive-amount physical-chemical synergistic flame-retardant silicone rubber; preparing the modified layered metal hydroxide nanosheet loaded halogen-free flame retardant through hydrothermal reaction, and mixing the modified layered metal hydroxide nanosheet loaded halogen-free flame retardant with expandable graphite in a ratio of 1:1, preparing a synergistic flame retardant, and preparing flame-retardant silicone rubber with a low addition amount of 5%; the silicone rubber before and after the flame retardant is added is contrasted and analyzed through a limited oxygen index test, a UL-94 test, a thermogravimetric analysis and a cone calorimetry, so that the high flame retardance and the high fireproof safety of the flame-retardant silicone rubber are fully displayed, and the mechanical properties before and after modification are analyzed, which shows that the processing performance of the silicone rubber is improved by the addition of the flame retardant.
The purpose of the invention is realized by the following technical scheme:
1. a preparation method of low-additive-amount physical-chemical synergistic flame-retardant silicone rubber is characterized by comprising the following steps:
the preparation process of the layered hydroxide loaded halogen-free flame retardant comprises the following steps:
a. weighing 3.8g of halogen-free flame retardant, placing the halogen-free flame retardant into a 250ml three-necked bottle, adding 100ml of deionized water, heating to 40 ℃, and mechanically stirring for about 2 hours to obtain uniformly dispersed milky suspension liquid A;
b. weighing 4.42g of divalent metal salt and 2.86g of trivalent metal salt, putting the divalent metal salt and the trivalent metal salt into a 100ml beaker, adding 50ml of deionized water, and stirring until the divalent metal salt and the trivalent metal salt are completely dissolved to obtain a transparent solution B;
c. under the action of mechanical stirring, dropwise adding the solution B into the liquid A by using a constant flow pump, keeping the temperature at 40 ℃, adjusting the pH to 8-9 by using an alkaline solution, and continuously stirring for 12 hours;
d. transferring the solution into a stainless steel sealed 200ml polytetrafluoroethylene reaction kettle, reacting in a 70 ℃ oven for 12h, and taking out;
d. when the temperature of the system is reduced to room temperature, carrying out vacuum filtration, repeatedly washing for 3-5 times by using deionized water, and collecting a filter cake;
e. drying the filter cake in a vacuum drying oven at 60 ℃ for 12h, taking out, and grinding to obtain a product, namely the layered hydroxide loaded halogen-free flame retardant;
-preparation of modified layered hydroxide loaded halogen-free flame retardant:
a. dissolving 4.5g of modifier and 0.5g of curing agent in 50ml of organic solvent, then adding 2g of layered hydroxide loaded halogen-free flame retardant, keeping the temperature at 30 ℃, and stirring for 30min;
b. vacuum filtering, repeatedly washing with organic solvent for 3-5 times, and curing in a vacuum drying oven for 1 hr;
d. taking out the filter cake, and grinding to obtain a product, namely the modified layered hydroxide loaded halogen-free flame retardant;
-preparation process of flame retardant silicone rubber composite:
a. weighing 2.5g of modified layered hydroxide-loaded halogen-free flame retardant and 2.5g of expandable graphite, placing the mixture in an agate mortar, fully grinding the mixture for 30min to obtain uniformly dispersed mixed flame retardant, and placing the mixed flame retardant in an oven at 60 ℃ for drying for 24h;
b. weighing 98g of silicon rubber, placing the silicon rubber in a 200mL polytetrafluoroethylene container, mechanically stirring at the speed of 5000r/min, adding the mixed flame retardant, and then continuing stirring for 30min. Then, the mechanical stirring speed is increased to 6000r/min, and after 2g of curing agent is added, continuous stirring is carried out for 2min;
c. injecting the silicon rubber mixed solution into a polytetrafluoroethylene mold, then putting the polytetrafluoroethylene mold into a vacuum drying oven for vacuumizing, and curing for 24 hours at room temperature;
d. taking the completely cured room temperature vulcanized silicone rubber composite material out of the mold, cutting off redundant parts at the edges, and cutting the room temperature vulcanized silicone rubber composite material sample plate into sample strips with the sizes suitable for flame retardant tests by using a cutting machine;
2. the method for preparing the low-additive-amount physical-chemical synergistic flame-retardant silicone rubber according to claim 1, wherein the halogen-free flame retardant is one or a combination of melamine polyphosphate, melamine pyrophosphate and melamine phosphate;
3. the method for preparing the low-additive-amount physical-chemical synergistic flame-retardant silicone rubber according to claim 1, wherein the divalent metal salt is one or a combination of transition metal salts such as nickel nitrate, cobalt acetate and ferric nitrate;
4. the method for preparing the low-addition-amount physico-chemical synergistic flame-retardant silicone rubber according to claim 1, characterized in that the organic solvent is one or a combination of toluene, ethyl acetate, tetrahydrofuran and xylene;
5. the method for preparing the low-additive-amount physical-chemical synergistic flame-retardant silicone rubber according to claim 1, wherein the alkaline solution is one or a combination of ammonia and sodium hydroxide solution;
6. the preparation method of the low-addition-amount physical-chemical synergistic flame-retardant silicone rubber according to claim 1, wherein the organic solvent is one or a combination of epoxy-modified silicone resin, methylphenyl silicone resin and acrylic acid-modified silicone resin;
7. the method for preparing the low-addition-amount physical-chemical synergistic flame-retardant silicone rubber according to claim 1, wherein the expandable graphite is one or a combination of the expansion ratios of 50, 100, 200 and 500;
compared with the prior art, the invention has the beneficial effects that:
a physical-chemical synergistic flame-retardant system with low addition amount is constructed, and the flame-retardant capability and the fireproof safety of the silicone rubber are efficiently enhanced; compared with the traditional single chemical intumescent flame retardant, the modified layered hydroxide loaded halogen-free flame retardant prepared by the patent effectively solves the problems of loose char formation and low flame retardant efficiency of the single flame retardant by loading the layered hydroxide; moreover, through hydrophobic modification, the compatibility and the dispersibility of the halogen-free flame retardant in the silicone rubber are effectively improved, and the flame retardant efficiency of the flame retardant is greatly improved; and by adding the expandable graphite, the problems of low halogen-free flame-retardant char formation amount and the worm phenomenon of the expandable graphite are solved, the compactness of the char layer is greatly improved, and the phenomenon that the mechanical property of the silicon rubber added with the flame retardant is reduced is further improved. The preparation method of the low-additive-amount physical-chemical synergistic flame-retardant silicone rubber has the advantages of being easy to prepare raw materials, low in additive amount, non-toxic, smokeless, halogen-free, efficient, environment-friendly and the like, realizes effective utilization and conversion of natural resources, and greatly improves the application value of the silicone rubber material. Therefore, the synergistic flame-retardant silicone rubber obtained by the method has better application potential.
Drawings
FIG. 1 is a graph of the limiting oxygen index test and UL-94 results for various silicone rubber samples provided in example 1.
FIG. 2 is a TGA and DTG curve of various silicone rubber samples provided in example 1;
fig. 3 is a taper calorimetry test result for different silicone rubber samples provided in example 1: (a) HRR; (b) THR; (c) SPR; (d) TSR;
fig. 4 is an image of the mechanical property test results of different silicone rubber samples provided in example 1;
Detailed Description
The invention is further illustrated by the following examples. These examples are intended to illustrate the invention only and do not limit the scope of the invention. The raw materials, reagents and the like used in the following examples were obtained commercially from conventional markets and the like. The following examples are within the scope of the invention as claimed.
Example 1:
the preparation process of the layered hydroxide loaded halogen-free flame retardant comprises the following steps:
a. weighing 3.8g of melamine polyphosphate, placing the melamine polyphosphate in a 250ml three-necked bottle, adding 100ml of deionized water, heating to 40 ℃, and mechanically stirring for about 2 hours to obtain uniformly dispersed milky suspension liquid A;
b. weighing 4.42g of nickel nitrate and 2.86g of aluminum nitrate, putting the nickel nitrate and the aluminum nitrate into a 100ml beaker, adding 50ml of deionized water, and stirring until the nickel nitrate and the aluminum nitrate are completely dissolved to obtain a transparent solution B;
c. under the action of mechanical stirring, dropwise adding the solution B into the liquid A by using a constant flow pump, keeping the temperature at 40 ℃, adjusting the pH to 8-9 by using ammonia water, and continuously stirring for 12 hours;
d. transferring the solution into a stainless steel sealed 200ml polytetrafluoroethylene reaction kettle, reacting in a 70 ℃ oven for 12h, and taking out;
d. when the temperature of the system is reduced to room temperature, carrying out vacuum filtration, repeatedly washing for 3-5 times by using deionized water, and collecting a filter cake;
e. drying the filter cake in a vacuum drying oven at 60 ℃ for 12h, taking out, and grinding to obtain a product, namely the layered hydroxide loaded halogen-free flame retardant;
-preparation of modified layered hydroxide loaded halogen-free flame retardant:
a. dissolving 4.5g of polydimethylsiloxane and 0.5g of curing agent in 50ml of ethyl acetate, then adding 2g of layered hydroxide loaded halogen-free flame retardant, keeping the temperature at 30 ℃, and stirring for 30min;
b. vacuum filtering, repeatedly washing with ethyl acetate for 3-5 times, and curing the wet powder in a vacuum drying oven for 1h;
d. taking out the filter cake, and grinding to obtain a product, namely the modified layered hydroxide loaded halogen-free flame retardant;
-preparation process of flame retardant silicone rubber composite:
a. weighing 2.5g of modified layered hydroxide-loaded halogen-free flame retardant and 2.5g of expandable graphite, placing the mixture in an agate mortar, fully grinding the mixture for 30min to obtain uniformly dispersed mixed flame retardant, and placing the mixed flame retardant in an oven at 60 ℃ for drying for 24h;
b. weighing 98g of silicon rubber, placing the silicon rubber in a 200mL polytetrafluoroethylene container, mechanically stirring at the speed of 5000r/min, adding the mixed flame retardant, and then continuously stirring for 30min. Then, the mechanical stirring speed is increased to 6000r/min, and after 2g of curing agent is added, continuous stirring is carried out for 2min;
c. injecting the silicon rubber mixed solution into a polytetrafluoroethylene mold, then putting the polytetrafluoroethylene mold into a vacuum drying oven for vacuumizing, and curing for 24 hours at room temperature;
d. taking the completely cured room temperature vulcanized silicone rubber composite material out of the mold, cutting off redundant parts on the edge, and cutting the room temperature vulcanized silicone rubber composite material sample plate into sample strips with the size suitable for the flame retardant test by using a cutting machine;
example 2:
the preparation process of the layered hydroxide loaded halogen-free flame retardant comprises the following steps:
a. weighing 3.8g of melamine pyrophosphate, placing the melamine pyrophosphate in a 250ml three-necked bottle, adding 100ml of deionized water, heating to 40 ℃, and mechanically stirring for about 2 hours to obtain uniformly dispersed milky suspension liquid A;
b. weighing 4.42g of nickel nitrate and 2.86g of aluminum nitrate, putting the nickel nitrate and the aluminum nitrate into a 100ml beaker, adding 50ml of deionized water, and stirring until the nickel nitrate and the aluminum nitrate are completely dissolved to obtain a transparent solution B;
c. under the action of mechanical stirring, dropwise adding the solution B into the liquid A by using a constant flow pump, keeping the temperature at 40 ℃, adjusting the pH to 8-9 by using ammonia water, and continuously stirring for 12 hours;
d. transferring the solution into a stainless steel sealed 200ml polytetrafluoroethylene reaction kettle, reacting in a 70 ℃ oven for 12h, and taking out;
d. when the temperature of the system is reduced to room temperature, carrying out vacuum filtration, repeatedly washing for 3-5 times by using deionized water, and collecting a filter cake;
e. drying the filter cake in a vacuum drying oven at 60 ℃ for 12h, taking out, and grinding to obtain a product, namely the layered hydroxide loaded halogen-free flame retardant;
-preparation of modified layered hydroxide loaded halogen-free flame retardant:
a. dissolving 4.5g of polydimethylsiloxane and 0.5g of curing agent in 50ml of ethyl acetate, then adding 2g of layered hydroxide loaded halogen-free flame retardant, keeping the temperature at 30 ℃, and stirring for 30min;
b. vacuum filtering, repeatedly washing with ethyl acetate for 3-5 times, and curing the wet powder in a vacuum drying oven for 1h;
d. taking out the filter cake, and grinding to obtain a product, namely the modified layered hydroxide loaded halogen-free flame retardant;
-preparation process of flame retardant silicone rubber composite:
a. weighing 2.5g of modified layered hydroxide-loaded halogen-free flame retardant and 2.5g of expandable graphite, placing the mixture in an agate mortar, fully grinding the mixture for 30min to obtain uniformly dispersed mixed flame retardant, and placing the mixed flame retardant in an oven at 60 ℃ for drying for 24h;
b. weighing 98g of silicon rubber, placing the silicon rubber in a 200mL polytetrafluoroethylene container, mechanically stirring at the speed of 5000r/min, adding the mixed flame retardant, and then continuing stirring for 30min. Then, the mechanical stirring speed is increased to 6000r/min, and after 2g of curing agent is added, continuous stirring is carried out for 2min;
c. injecting the silicon rubber mixed solution into a polytetrafluoroethylene mold, then putting the polytetrafluoroethylene mold into a vacuum drying oven for vacuumizing, and curing for 24 hours at room temperature;
d. taking the completely cured room temperature vulcanized silicone rubber composite material out of the mold, cutting off redundant parts on the edge, and cutting the room temperature vulcanized silicone rubber composite material sample plate into sample strips with the size suitable for the flame retardant test by using a cutting machine;
example 3
The preparation process of the layered hydroxide loaded halogen-free flame retardant comprises the following steps:
a. weighing 3.8g of melamine poly salt, placing the melamine poly salt in a 250ml three-necked bottle, adding 100ml of deionized water, heating to 40 ℃, and mechanically stirring for about 2 hours to obtain uniformly dispersed milky suspension A;
b. weighing 4.42g of zinc nitrate and 2.86g of aluminum nitrate, placing the zinc nitrate and the aluminum nitrate into a 100ml beaker, adding 50ml of deionized water, and stirring until the zinc nitrate and the aluminum nitrate are completely dissolved to obtain a transparent solution B;
c. under the action of mechanical stirring, dropwise adding the solution B into the liquid A by using a constant flow pump, keeping the temperature at 40 ℃, adjusting the pH to 8-9 by using ammonia water, and continuously stirring for 12 hours;
d. transferring the solution into a stainless steel sealed 200ml polytetrafluoroethylene reaction kettle, reacting in a 70 ℃ oven for 12h, and taking out;
d. when the temperature of the system is reduced to room temperature, carrying out vacuum filtration, repeatedly washing for 3-5 times by using deionized water, and collecting a filter cake;
e. drying the filter cake in a vacuum drying oven at 60 ℃ for 12h, taking out, and grinding to obtain a product, namely the layered hydroxide loaded halogen-free flame retardant;
-preparation of modified layered hydroxide loaded halogen-free flame retardant:
a. dissolving 4.5g of polydimethylsiloxane and 0.5g of curing agent in 50ml of ethyl acetate, then adding 2g of layered hydroxide loaded halogen-free flame retardant, keeping the temperature at 30 ℃, and stirring for 30min;
b. vacuum filtering, repeatedly washing with ethyl acetate for 3-5 times, and curing the wet powder in a vacuum drying oven for 1h;
d. taking out the filter cake, and grinding to obtain a product, namely the modified layered hydroxide loaded halogen-free flame retardant;
-preparation process of flame retardant silicone rubber composite:
a. weighing 2.5g of modified layered hydroxide-loaded halogen-free flame retardant and 2.5g of expandable graphite, placing the mixture in an agate mortar, fully grinding the mixture for 30min to obtain uniformly dispersed mixed flame retardant, and placing the mixed flame retardant in an oven at 60 ℃ for drying for 24h;
b. weighing 98g of silicon rubber, placing the silicon rubber in a 200mL polytetrafluoroethylene container, mechanically stirring at the speed of 5000r/min, adding the mixed flame retardant, and then continuing stirring for 30min. Then, the mechanical stirring speed is increased to 6000r/min, and after 2g of curing agent is added, continuous stirring is carried out for 2min;
c. injecting the silicon rubber mixed solution into a polytetrafluoroethylene mold, then putting the polytetrafluoroethylene mold into a vacuum drying oven for vacuumizing, and curing for 24 hours at room temperature;
d. and taking the completely cured room temperature vulcanized silicone rubber composite material out of the mold, cutting off redundant parts at the edge, and cutting the room temperature vulcanized silicone rubber composite material sample plate into sample strips with the size suitable for the flame-retardant test by using a cutting machine.

Claims (7)

1. A preparation method of low-additive-amount physical-chemical synergistic flame-retardant silicone rubber is characterized by comprising the following steps:
the preparation process of the layered hydroxide loaded halogen-free flame retardant comprises the following steps:
a. weighing 3.8g of halogen-free flame retardant, placing the halogen-free flame retardant into a 250ml three-necked bottle, adding 100ml of deionized water, heating to 40 ℃, and mechanically stirring for about 2 hours to obtain uniformly dispersed milky suspension liquid A;
b. weighing 4.42g of divalent metal salt and 2.86g of trivalent metal salt, putting the divalent metal salt and the trivalent metal salt into a 100ml beaker, adding 50ml of deionized water, and stirring until the divalent metal salt and the trivalent metal salt are completely dissolved to obtain a transparent solution B;
c. under the action of mechanical stirring, dropwise adding the solution B into the liquid A by using a constant flow pump, keeping the temperature at 40 ℃, adjusting the pH to 8-9 by using an alkaline solution, and continuously stirring for 12 hours;
d. transferring the solution into a stainless steel sealed 200ml polytetrafluoroethylene reaction kettle, reacting in a 70 ℃ oven for 12h, and taking out;
d. when the temperature of the system is reduced to room temperature, carrying out vacuum filtration, repeatedly washing for 3-5 times by using deionized water, and collecting a filter cake;
e. drying the filter cake in a vacuum drying oven at 60 ℃ for 12h, taking out, and grinding to obtain a product, namely the layered hydroxide loaded halogen-free flame retardant;
-preparation of modified layered hydroxide supported halogen-free flame retardant:
a. dissolving 4.5g of modifier and 0.5g of curing agent in 50ml of organic solvent, then adding 2g of layered hydroxide loaded halogen-free flame retardant, keeping the temperature at 30 ℃, and stirring for 30min;
b. vacuum filtering, repeatedly washing with organic solvent for 3-5 times, and curing in a vacuum drying oven for 1 hr;
d. taking out the filter cake, and grinding to obtain a product, namely the modified layered hydroxide loaded halogen-free flame retardant;
-preparation process of flame retardant silicone rubber composite:
a. weighing 2.5g of modified layered hydroxide-loaded halogen-free flame retardant and 2.5g of expandable graphite, placing the materials in an agate mortar, fully grinding the materials for 30min to obtain uniformly dispersed mixed flame retardant, and placing the mixed flame retardant in an oven at 60 ℃ for drying for 24h;
b. weighing 98g of silicon rubber, placing the silicon rubber in a 200mL polytetrafluoroethylene container, mechanically stirring at the speed of 5000r/min, adding the mixed flame retardant, and then continuously stirring for 30min. Then, the mechanical stirring speed is increased to 6000r/min, and after 2g of curing agent is added, continuous stirring is carried out for 2min;
c. injecting the silicon rubber mixed solution into a polytetrafluoroethylene mold, then putting the polytetrafluoroethylene mold into a vacuum drying oven for vacuumizing, and curing for 24 hours at room temperature;
d. and taking the completely cured room temperature vulcanized silicone rubber composite material out of the mold, cutting off redundant parts at the edge, and cutting the room temperature vulcanized silicone rubber composite material sample plate into sample strips with the size suitable for the flame retardant test by using a cutting machine.
2. The method for preparing the low-additive-amount physical-chemical synergistic flame-retardant silicone rubber according to claim 1, wherein the halogen-free flame retardant is one or a combination of melamine polyphosphate, melamine pyrophosphate and melamine phosphate.
3. The method for preparing the physically-chemically synergistic flame-retardant silicone rubber with low addition amount according to claim 1, wherein the divalent metal salt is one or a combination of transition metal salts such as nickel nitrate, cobalt acetate and ferric nitrate.
4. The method for preparing the low-addition-amount physico-chemical synergistic flame-retardant silicone rubber according to claim 1, wherein the organic solvent is one or a combination of toluene, ethyl acetate, tetrahydrofuran and xylene.
5. The method for preparing the low-additive-amount physico-chemical synergistic flame-retardant silicone rubber according to claim 1, wherein the alkaline solution is one or a combination of ammonia and sodium hydroxide solution.
6. The method for preparing the low-addition-amount physical-chemical synergistic flame-retardant silicone rubber according to claim 1, wherein the organic solvent is one or a combination of epoxy-modified silicone resin, methylphenyl silicone resin and acrylic acid-modified silicone resin.
7. The method for preparing the low-addition-amount physico-chemical synergistic flame-retardant silicone rubber according to claim 1, characterized in that the expandable graphite is one or a combination of the expansion ratios of 50, 100, 200 and 500.
CN202211036944.5A 2022-08-29 2022-08-29 Preparation method of low-additive-amount physical-chemical synergistic flame-retardant silicone rubber Pending CN115521620A (en)

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