CN113637328B

CN113637328B - Flame-retardant insulating silicone rubber and preparation method thereof

Info

Publication number: CN113637328B
Application number: CN202110822342.1A
Authority: CN
Inventors: 杨连科; 尤小姿; 周游; 陈凯旋; 朱艳艳; 邵珺
Original assignee: Zhejiang Xinan Chemical Industrial Group Co Ltd
Current assignee: Zhejiang Xinan Chemical Industrial Group Co Ltd
Priority date: 2021-07-21
Filing date: 2021-07-21
Publication date: 2022-03-25
Anticipated expiration: 2041-07-21
Also published as: CN113637328A

Abstract

The invention belongs to the technical field of rubber, and particularly relates to flame-retardant insulating silicone rubber and a preparation method thereof. The flame-retardant insulating silicone rubber comprises the following raw materials: raw methyl vinyl silicone rubber, white carbon black, a structural control agent, a mold release agent, a composite flame-retardant filler and a heat-resistant flame-retardant auxiliary agent. The preparation method is simple, and the prepared flame-retardant insulating silicone rubber solves the problems of large addition amount of inorganic filler, difficult dispersion and poor heat resistance.

Description

Flame-retardant insulating silicone rubber and preparation method thereof

Technical Field

The invention belongs to the technical field of rubber, and particularly relates to flame-retardant insulating silicone rubber and a preparation method thereof.

Background

Methyl vinyl silicone rubber, a rubber based on polydimethylsiloxane, has a wide range of service temperatures, is generally considered to have stable performance for a long time at-40 ℃ to 200 ℃, and can be used at high temperatures for a long time. The silicon rubber is difficult to ignite after burning, toxic gas is not generated after burning, the burnt powder is silicon dioxide, and the combustion product is non-toxic and difficult to continue burning, so the silicon rubber is a good flame retardant material. However, silicone rubber itself does not have flame retardant properties, and ignition continues to occur, and in order to obtain good flame retardancy, a flame retardant is added thereto.

The common flame retardant is halogen flame retardant, nitrogen and phosphorus flame retardant and inorganic flame retardant.

Patent application CN 201310461092 uses 20-30 parts of halogen flame retardant of decabromodiphenylethane to obtain good flame retardant effect, but the halogen flame retardant burns to generate a large amount of smog and toxic gas, and in the fire disaster, the halogen flame retardant is easily suffocated after being inhaled by a human body, is not beneficial to the health of the human body, and is gradually reduced in use at present.

In patent application CN201911392740, ammonium polyphosphate is used as a flame retardant, and is matched with a platinum flame retardant and rare earth heat-resistant agents such as zirconium phosphate and nano cerium oxide to obtain the high-strength heat-resistant silicone rubber. However, ammonium polyphosphate begins to slowly decompose at 150 ℃, begins to degrade at a temperature higher than 240 ℃, and the degradation product is polyphosphoric acid, so that the mechanical properties of the silicone rubber can be greatly influenced after the ammonium polyphosphate is used for a long time in a high-temperature environment, and a good heat-resistant effect cannot be obtained at a high temperature. In order to obtain better heat resistance, a rare earth heat-resistant agent is added. And the silicon rubber added with the ammonium polyphosphate can generate an expansion layer after high-temperature combustion, and under the condition of high voltage, the phenomena of tracking and high-temperature corrosion can be generated.

The aluminum hydroxide and the magnesium hydroxide are common inorganic additives, can release crystal water during combustion, absorb heat, dilute combustible gas and have better flame retardant effect. However, the addition of a large amount of inorganic substances can greatly damage the mechanical properties of the silica gel material.

Disclosure of Invention

In order to overcome the technical problems, the invention provides flame-retardant insulating silicone rubber and a preparation method thereof, and solves the problems of large addition amount of inorganic filler, difficult dispersion and poor heat resistance.

In order to achieve the above purpose, the technical scheme provided by the invention is as follows:

the flame-retardant insulating silicone rubber comprises the following raw materials: raw methyl vinyl silicone rubber, white carbon black, a structural control agent, a mold release agent, a composite flame-retardant filler and a heat-resistant flame-retardant auxiliary agent.

Preferably, the raw materials comprise the following components in parts by weight: 100 parts of methyl vinyl silicone rubber crude rubber, 10-50 parts of white carbon black, 0.1-4 parts of structural control agent, 0.1-2 parts of release agent, 50-150 parts of composite flame-retardant filler and 0.5-10 parts of heat-resistant flame-retardant auxiliary agent.

Preferably, the raw materials comprise the following components in parts by weight: 100 parts of methyl vinyl silicone rubber crude rubber, 10-50 parts of white carbon black, 1-4 parts of a structural control agent, 0.1-2 parts of a release agent, 50-150 parts of a composite flame-retardant filler and 1-10 parts of a heat-resistant flame-retardant auxiliary agent.

Preferably, the raw methyl vinyl silicone rubber is vinyl-terminated raw rubber, the molecular weight is 50-80 ten thousand g/mol, and the vinyl content is 0.03-3.00%;

preferably, the vinyl-terminated raw rubber has a molecular weight of 60-80 ten thousand g/mol and a vinyl content of 0.03-1%.

Preferably, the specific surface area of the white carbon black is 50-400m²/g。

Preferably, the white carbon black is fumed silica with a specific surface area of 100-200m²/g。

Preferably, the structural control agent is any one or more of diphenyl silanediol, dimethyl dimethoxysilane, hexamethyldisilazane, vinyl disilazane and/or hydroxyl silicone oil.

Preferably, the structural control agent is a hydroxy silicone oil.

Preferably, the release agent is any one or more of fatty acid, stearate, or/and fatty acid metal salt.

Preferably, the release agent is zinc stearate.

Preferably, the composite flame retardant filler is a mixture of aluminum hydroxide, magnesium hydroxide, zinc borate and silicate.

Preferably, the silicate is talc, mica, wollastonite, etc., more preferably talc;

preferably, Na of the aluminum hydroxide and the magnesium hydroxide₂O content less than or equal to 0.3 percent and grain diameter D₅₀0.1-70 μm, preferably 0.1-20 μm; .

Preferably, Na of the aluminum hydroxide and the magnesium hydroxide₂O content less than or equal to 0.2 percent and grain diameter D₅₀Is 0.1-10 μm.

Preferably, the zinc borate is hydrated zinc borate and has the general formula XZnO. YB₂O₃.ZH₂O, wherein Z is 1 to 10, preferably 1-10 zinc borate hydrate, 3-zinc borate hydrate, 3.5-zinc borate hydrate, 7-zinc borate hydrate, D₅₀Less than 10 μm. Further preferred is 3.5 parts zinc borate hydrate, D₅₀Is 0.5-5 μm in diameter,

preferably, the particle size D of the silicate₅₀Is 0.5 to 25 μm, more preferably 0.5 to 15 μm.

Preferably, the ratio of aluminum hydroxide: magnesium hydroxide: zinc borate: the mass ratio of the silicate is 60-100: 5-30: 1-30: 1 to 30; more preferably 70 to 100: 5-20: 1-20: 1 to 20; more preferably 80 to 90: 10-20: 2-10: 2-10.

Preferably, the preparation method of the composite flame-retardant filler comprises the following steps: through dry treatment, adding aluminum hydroxide, zinc borate, magnesium hydroxide and silicate into a kneader or a high-speed dispersion machine, setting the rotating speed to be 25-60HZ, spraying silane coupling agent or/and stearic acid diluted by alcohol, stirring for 5-60min, heating to 100 ℃ and 150 ℃, and continuously stirring for 1-3h to obtain the composite flame-retardant filler;

preferably, the silane coupling agent is one or more of methyltrimethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, methyltrimethoxysilane, methyltrivinylsilane, vinyltrimethoxysilane, vinyltrivinylsilane, vinyltris (β -methoxyethoxy) silane, aminopropyltriethoxysilane, or/and epoxypropyltriethoxysilane, more preferably aminopropyltriethoxysilane.

Preferably, the heat-resistant flame-retardant auxiliary agent is phenyl silicone oil or phenyl crude rubber and a composition containing a platinum compound and a nitrogen-containing compound;

wherein the mass ratio of the phenyl silicone oil or the phenyl crude rubber to the platinum-containing compound and the nitrogen-containing compound is 100: 1-100: 1-10, more preferably 100: 1-10: 1-5.

Preferably, the phenyl silicone oil is methyl phenyl silicone oil, the phenyl content is 5-30%, and the viscosity range is 50-1000 cs; preferably, the phenyl content is 10-30% and the viscosity ranges from 50-300 cs.

Preferably, the phenyl crude rubber is methyl vinyl phenyl crude rubber, the content of phenyl is 5-30%, and the molecular weight is 40-80 ten thousand g/mol; preferably, the phenyl content is 10-30% and the molecular weight is 40-70 ten thousand g/mol.

Preferably, the nitrogen-containing compound is triazole and derivatives thereof, and further preferably benzotriazole.

Preferably, the platinum-containing compound is a platinum catkin catalyst, chloroplatinic acid and a platinum-containing complex or platinum-containing support, wherein the platinum content should be 10-10000 ppm.

Preferably, the platinum-containing compound is a platinum catalyst with a platinum content of

100-10000ppm, more preferably, the platinum content is 5000-10000 ppm.

Preferably, the preparation method of the heat-resistant flame-retardant auxiliary comprises the steps of putting phenyl silicone oil or phenyl crude rubber into a kneader, adding a nitrogen-containing compound and a platinum-containing compound, and uniformly stirring to obtain the heat-resistant flame-retardant auxiliary.

Preferably, the mass ratio of the heat-resistant flame-retardant auxiliary agent to the composite flame-retardant filler is 1-10: 50 to 150, preferably 1 to 5: 60 to 120, more preferably 1 to 4: 60-100.

The invention also aims to provide a preparation method of the flame-retardant insulating silicone rubber, which comprises the following steps:

(1) putting the methyl vinyl silicone rubber, the white carbon black, the structural control agent and the release agent into a kneading machine for kneading and mixing into a mass;

(2) adding the composite flame-retardant filler, and continuing kneading;

(3) heating and continuously mixing, and cooling to room temperature;

(4) and continuously adding the heat-resistant flame-retardant auxiliary agent, uniformly kneading, taking out, adding the bis-penta vulcanizing agent, uniformly mixing in a thin-pass manner, and then vulcanizing.

Preferably, in the step (2), the kneading is continued for 30 to 60 min;

preferably, in the step (3), the temperature of the temperature rise is up to 130-150 ℃;

preferably, in the step (3), the mixing time is 1-3 h;

preferably, in step (3), in step (2), the mixing is carried out under a vacuum of 200 kPa and 650 kPa.

Preferably, in the step (4), the number of the thin passes is 10 to 20.

Preferably, in the step (4), the vulcanization is carried out at the temperature of 150 ℃ and 200 ℃ for 5-30 min.

Preferably, in step (4), the vulcanization is carried out using a press vulcanizer at 175 ℃ for 5 min.

Compared with the prior art, the invention has the technical advantages that:

(1) the inorganic flame-retardant filler is prepared by compounding the inorganic flame-retardant filler in advance, using the surfactant and the silane coupling agent for advanced treatment, adding the silicate inorganic filler with good fluidity to obtain the inorganic flame-retardant filler which is simple to disperse, and using the platinum compound and the phenyl-containing polysiloxane in a matching manner to greatly reduce the amount of the inorganic filler, so that the flame-retardant silicone rubber which is simple to prepare, free of halogen addition, capable of being used at 200 ℃ for a long time and capable of reaching the V0 level of a product with the thickness of 1-3mm is obtained, and can be widely used in the fields of heat-resistant flame-retardant sheaths, sundries, wires and cables, insulating sheaths and the like.

(2) The aluminum hydroxide and the magnesium hydroxide are used as flame-retardant fillers, and the inorganic flame retardant can reduce the smoke amount and reduce the dripping. The low sodium content is beneficial to improving the flame retardance of the flame-retardant silicone rubber and has better electrical property. The smaller the particle size, the better the mechanical properties to the silicone rubber; the zinc borate also has better effects of flame retardance, smoke suppression and drop reduction. The zinc borate loses crystal water at the temperature of 300-400 ℃, the temperature of the surface of the silicon rubber can be reduced by water evaporation, and simultaneously the content of oxygen on the surface of the silicon rubber is diluted, so that the smoldering phenomenon is effectively inhibited. And the heat absorbed by the zinc borate after being decomposed by heat is less than that of aluminum hydroxide and magnesium hydroxide, so that the zinc borate can quickly release crystal water, can form synergistic flame retardance with the aluminum hydroxide, and has better flame retardant effect. Meanwhile, silicate with good fluidity, such as talcum powder, is added, so that the fluidity of the flame retardant can be increased.

(3) The particle size of the zinc borate plays an important role in influencing the effect, the too small particle size is difficult to disperse, and the larger particle size reduces the flame retardant effect.

Detailed Description

The invention is further described below with reference to specific embodiments. So that the technical scheme of the invention can be more easily understood and mastered, but the invention is not limited to the technical scheme. The experimental methods described in the following examples are all conventional methods unless otherwise specified; the reagents and materials are commercially available, unless otherwise specified.

Example 1

Setting the rotating speed to be 60Hz in a high-speed dispersion machine, adding aluminum hydroxide, magnesium hydroxide, zinc borate and talcum powder (the mixture ratio is shown in table 1), and spraying 1 mass percent of aminopropyl triethoxysilane and 0.5 mass percent of stearic acid by using ethanol solution; after uniform spraying, kneading for 30min at 100 ℃, and continuously stirring for 3h to obtain the composite flame-retardant filler;

after the phenyl silicone oil is put into a kneader, a nitrogen-containing compound and a platinum-containing compound are added, and the mixture is uniformly stirred to prepare the heat-resistant flame-retardant auxiliary agent (the composition of the raw materials is shown in table 2);

taking 100 parts of vinyl-terminated methyl vinyl raw rubber with the molecular weight of 70 ten thousand g/mol and the vinyl content of 0.03 percent, 2 parts of hydroxyl silicone oil and 0.3 part of zinc stearate; putting into a kneading machine; adding white carbon black (specific surface area 200 m)²20 parts of the mixture per gram), kneading the mixture into a block, adding 120 parts of the composite flame-retardant filler, kneading the block, heating the block to 150 ℃, vacuumizing the block for 60min, and cooling the block to room temperature;

and continuously adding 5 parts of heat-resistant flame-retardant auxiliary agent, uniformly kneading, taking out, adding 1 wt% of bis-dipentane vulcanizing agent, thinly passing for 10 times, and vulcanizing at 175 ℃ for 5 min.

Example 2

Setting the rotating speed to be 25Hz in a high-speed dispersion machine, adding aluminum hydroxide, magnesium hydroxide, zinc borate and talcum powder (the mixture ratio is shown in table 1), and spraying 1 mass percent of methyltrimethoxysilane and 0.5 mass percent of stearic acid by using an ethanol solution; after uniform spraying, kneading for 10min at 150 ℃, and continuously stirring for 1h to obtain the composite flame-retardant filler;

taking 100 parts of vinyl-terminated methyl vinyl raw rubber with the molecular weight of 50 ten thousand g/mol and the vinyl content of 0.05 percent, 1 part of hydroxyl silicone oil and 1 part of zinc stearate; putting into a kneading machine; adding fumed silica (specific surface area 50 m)²20 parts of the mixture per gram), adding 50 parts of the composite flame-retardant filler after kneading into a mass, heating to 150 ℃, vacuumizing for 60min, and cooling to room temperature;

and continuously adding 3 parts of heat-resistant flame-retardant auxiliary agent, uniformly kneading, taking out, adding 1 wt% of bis-dipenta vulcanizing agent, thinly passing for 5 times, and vulcanizing at 175 ℃ for 5 min.

Example 3

Setting the rotating speed at 50Hz in a high-speed dispersion machine, adding aluminum hydroxide, magnesium hydroxide, zinc borate and talcum powder (the mixture ratio is shown in table 1), and spraying 1 mass percent of dimethyl diethoxy silane and 0.5 mass percent of stearic acid by using ethanol solution; after uniform spraying, kneading for 60min at 100 ℃, and continuously stirring for 2h to obtain the composite flame-retardant filler;

putting the phenyl crude rubber into a kneader, adding a nitrogen-containing compound and a platinum-containing compound, and uniformly stirring to obtain a heat-resistant flame-retardant auxiliary agent (the composition of the raw material formula is shown in table 2);

taking 100 parts of vinyl-terminated methyl vinyl raw rubber, 4 parts of diphenyl silanediol and 2 parts of stearic acid, wherein the molecular weight of the raw rubber is 80 ten thousand g/mol, the vinyl content of the raw rubber is 1 percent; putting into a kneading machine; adding white carbon black (specific surface area 400 m)²20 parts of the mixture per gram), adding 100 parts of the composite flame-retardant filler after kneading and agglomerating, heating to 150 ℃, vacuumizing for 60min, and cooling to room temperature;

and continuously adding 4 parts of heat-resistant flame-retardant auxiliary agent, uniformly kneading, taking out, adding 1 wt% of bis-penta vulcanizing agent, thinly passing for 10 times, and vulcanizing at 175 ℃ for 5 min.

Comparative example 1

The difference from example 1 is only that the raw material is different (see table 3), and the zinc borate is replaced by the fine silica powder, and the rest of the operation is the same.

Comparative example 2

The difference from the example 1 is only that the compounding ratio of the composite flame retardant is different (see table 3), and the rest operation is the same.

Comparative example 3

Comparative example 4

The only difference from example 1 is that the vinyl terminated green rubber has a molecular weight of 40 ten thousand g/mol, and the rest of the procedure is the same.

Comparative example 5

The only difference from example 1 is that the vinyl content of the vinyl terminated methyl vinyl green gum is 5% and the rest of the procedure is the same.

Comparative example 6

The difference from example 1 is only in that the raw materials are different, and methyl silicone oil is used instead of phenyl silicone oil for the heat-resistant flame-retardant auxiliary, and the rest of the operation is the same.

Comparative example 7

The difference from example 1 is only that the platinum content of the heat-resistant flame-retardant auxiliary was 0 ppm.

TABLE 1 composite flame-retardant Filler formulation

TABLE 2 Heat-resistant flame-retardant auxiliary formulation

Table 3 comparative example composite flame retardant filler formulation

Evaluation of Performance

1. Mechanical property and flame retardant property

The hardness, plasticity, tensile strength and elongation are tested according to GB/T531.1 (Shore A hardness), GB/T12828, GB/T528 and GB/T529, and the flame retardant test is carried out according to GB/T10707 vertical flame retardant test method.

TABLE 4 mechanical Properties

TABLE 5 flame retardance Properties

TABLE 6 judgment standards for flame retardancy

Standard of merit	V0	V1
			Maximum value of first combustion after flame t1	≤10s	≤30s
Maximum value of second combustion after flame t2	≤10s	≤30s
			Total combustion time tf of five-spline afterglow	≤50s	≤250s

2. Aging Property

Aging conditions are as follows: and (3) carrying out a heat aging oven at 200 ℃ for 96h, and measuring the mechanical properties according to the same conditions after aging.

TABLE 7 aging Properties

Therefore, the rubber provided by the invention has better mechanical property and flame retardant property, and meanwhile, the raw material composition and the preparation method have important influence on the effect.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of elements or steps not listed in a claim. The usage of the words first, second and third, etcetera do not indicate any ordering and these words may be interpreted as names.

Claims

1. The flame-retardant insulating silicone rubber comprises the following raw materials in parts by weight: 100 parts of methyl vinyl silicone rubber crude rubber, 10-50 parts of white carbon black, 0.1-4 parts of a structural control agent, 0.1-2 parts of a release agent, 50-150 parts of a composite flame-retardant filler and 0.5-10 parts of a heat-resistant flame-retardant auxiliary agent;

the methyl vinyl silicone rubber raw rubber is vinyl-terminated raw rubber, the molecular weight is 50-80 ten thousand g/mol, and the vinyl content is 0.03-3.00%;

the composite flame-retardant filler is a mixture of aluminum hydroxide, magnesium hydroxide, zinc borate and silicate; the aluminum hydroxide: magnesium hydroxide: zinc borate: the mass ratio of the silicate is 60-120: 5-30: 1-30: 1 to 30;

the silicate is talcum powder, mica or wollastonite;

the heat-resistant flame-retardant auxiliary agent is phenyl silicone oil or phenyl crude rubber and a composition containing a platinum compound and a nitrogen-containing compound; wherein the mass ratio of the phenyl silicone oil or the phenyl crude rubber to the platinum-containing compound and the nitrogen-containing compound is 100: 1-100: 1-10;

the nitrogen-containing compound is triazole and derivatives thereof.

2. The flame-retardant insulating silicone rubber according to claim 1, wherein the mass ratio of the heat-resistant flame-retardant auxiliary to the composite flame-retardant filler is 1-10: 50-150.

3. The flame-retardant insulating silicone rubber according to claim 2, wherein the mass ratio of the heat-resistant flame-retardant auxiliary to the composite flame-retardant filler is 1-5: 60-120.

4. The flame-retardant insulating silicone rubber according to claim 3, wherein the mass ratio of the heat-resistant flame-retardant auxiliary to the composite flame-retardant filler is 1-4: 60-100.

5. The flame-retardant insulating silicone rubber according to claim 1, wherein the white carbon black has a specific surface area of 50 to 400m²/g。

6. The flame-retardant insulating silicone rubber according to claim 1, wherein the structural control agent is any one or more of diphenylsilanediol, dimethyldimethoxysilane, hexamethyldisilazane, vinyldisilazane and/or hydroxysilicone oil.

7. The flame-retardant, insulating silicone rubber according to claim 1, wherein the release agent is any one or more of a fatty acid, a stearate, and/or a fatty acid metal salt.

8. The flame-retardant insulating silicone rubber according to claim 1, wherein the ratio of aluminum hydroxide: magnesium hydroxide: zinc borate: the mass ratio of the silicate is 70-100: 5-20: 1-20: 1 to 20; na of the aluminum hydroxide and the magnesium hydroxide₂O content less than or equal to 0.3 percent and grain diameter D₅₀0.1-70 μm;

the preparation method of the composite flame-retardant filler comprises the following steps: adding aluminum hydroxide, silicate, zinc borate and magnesium hydroxide into a kneader or a high-speed dispersion machine, setting the rotating speed to be 25-60Hz, spraying silane coupling agent or/and stearic acid diluted by alcohol, stirring for 5-60min, heating to 100 ℃ and 150 ℃, and continuously stirring for 1-3h to obtain the composite flame-retardant filler.

9. The flame-retardant, insulating silicone rubber according to claim 8, wherein the ratio of aluminum hydroxide: magnesium hydroxide: zinc borate: the mass ratio of the silicate is 80-100: 10-20: 2-10: 2-10.

10. The flame-retardant, insulating silicone rubber according to claim 1, wherein the silicate is talc.

11. The flame-retardant, insulating silicone rubber according to claim 8, wherein the aluminum hydroxide and magnesium hydroxide have a particle diameter D₅₀Is 0.1-20 μm.

12. The flame-retardant insulating silicone rubber according to claim 1, wherein the mass ratio of the phenyl silicone oil or the phenyl crude rubber to the platinum-containing compound and the nitrogen-containing compound is 100: 1-10: 1-5;

the preparation method of the heat-resistant flame-retardant auxiliary agent comprises the steps of putting phenyl silicone oil or phenyl crude rubber into a kneading machine, adding a nitrogen-containing compound and a platinum-containing compound, and uniformly stirring to obtain the heat-resistant flame-retardant auxiliary agent; the phenyl silicone oil is methyl phenyl silicone oil, the phenyl content is 5-30%, and the viscosity range is 50-1000 cs;

the phenyl crude rubber is methyl vinyl phenyl crude rubber, the phenyl content is 5-30%, and the molecular weight is 40-80 ten thousand g/mol;

the platinum-containing compound is a platinum catalyst or a platinum-containing complex, wherein the platinum content is 10-10000 ppm.

13. The flame-retardant insulating silicone rubber according to claim 1, wherein the nitrogen-containing compound is benzotriazole.

14. The method for preparing a flame-retardant insulating silicone rubber according to any one of claims 1 to 13, comprising the steps of:

(2) adding the composite flame-retardant filler, and continuing kneading;

(3) heating and continuously mixing, and cooling to room temperature;