A high-performance flame-retardant heat-insulating mica material and its application

Abstract

The present invention discloses a high-performance flame-retardant and heat-insulating mica material and its application, and relates to the technical field of polymer materials. The high-performance flame-retardant and heat-insulating mica material disclosed in the present invention comprises the following raw materials in weight percentage: 20-40% modified mica, 0.5-1% vulcanizing agent, and silicone rubber remainder. The preparation method of modified mica comprises modifying the surface of mica nano powder by dopamine hydrochloride to obtain component one; and then reacting component one with boric acid to obtain modified mica. The present invention also prepares a new type of silicone rubber. The present application utilizes the prepared modified mica and silicone rubber to vulcanize under the action of a vulcanizing agent to prepare a high-performance flame-retardant and heat-insulating mica material, and the prepared material has the characteristics of good flame retardancy and excellent heat insulation performance.

Description

Technical Field

[0001] The invention relates to the technical field of polymer materials, and in particular to a high-performance flame-retardant heat-insulating mica material and application thereof. Background Art

[0002] Silicone rubber is a kind of polymer compound with repeated Si-O bonds as the main chain and organic groups such as methyl, vinyl, phenyl and other organic groups as the side chains. Due to its special structure, silicone rubber has good aging resistance, high and low temperature resistance, weather resistance, electrical insulation performance and relatively low heat release rate. As a result, silicone rubber is widely used in the fields of electricity and electronics. Silicone rubber products used in the power field include ignition cables, ship cables and power cables, etc. Silicone rubber products used in the electronics industry also include electrical connectors, electrical insulation layers and electrical sealing shock absorbers. The gas produced when pure silicone rubber burns is non-toxic and does not drip. The residue produced after combustion is silicon dioxide, which covers the surface of the polymer and has the function of blocking heat transfer and mass transfer. However, the oxygen index of silicone rubber itself is far lower than 30, which is lower than the requirement of the industry standard that the manufacturing cable material must have high flame retardancy. In addition, silicone rubber is flammable. Once it catches fire and continues to burn, it has a potential combustion risk, which limits its application in the field of wires and cables.

[0003] Mica is one of the most widely used fillers for silicone rubber flame retardant fillers. Mica can make the cable have excellent electrical and mechanical properties at the same time. When silicone rubber is blended with mica, the layer structure of mica can not only adsorb silicone rubber molecular chains, hinder the movement of silicone rubber segments, increase the cross-linking degree of silicone rubber, and improve the thermal stability of silicone rubber, but also the layer structure of mica can block and reduce the transmission efficiency of heat and oxygen. Mica can also effectively increase the amount of silicone rubber residue under high temperature combustion, promote the formation of ceramic residual layer on the surface, and effectively flame retardant and heat insulating. Mica can effectively improve the strength of the ceramic layer when promoting the formation of the ceramic layer, but the shrinkage rate after combustion will also increase, causing the ceramic layer to easily break, and with the addition of mica, it is easy to cause problems such as increased processing difficulty and deterioration of mechanical properties after cross-linking of silicone rubber. Summary of the invention

[0004] The purpose of the present invention is to provide a high-performance flame-retardant heat-insulating mica material and its application to solve the following technical problems:

[0005] Directly adding mica to the existing silicone rubber results in a high shrinkage rate of the ceramic residual layer produced after the material is burned, and the ceramic layer is easy to break; and the addition of mica leads to high difficulty in material processing, and the mechanical properties of the processed material are poor.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A high-performance flame-retardant heat-insulating mica material comprises the following raw materials in percentage by weight: 20-40% of modified mica, 0.5-1% of a vulcanizing agent, and the remainder of silicone rubber.

[0008] As a further solution of the present invention: the preparation method of modified mica comprises the following steps:

[0009] S1: Add mica nanopowder and Tris buffer into a reaction bottle and disperse evenly, add dopamine hydrochloride, disperse evenly, stir at room temperature for 6-12 hours, wash, dry and grind to obtain component 1;

[0010] S2: Add component 1, boric acid and xylene into a reaction kettle, stir evenly, heat to 100-110° C., reflux for 1-3 hours, cool, filter, wash and dry to obtain modified mica.

[0011] As a further solution of the present invention: the addition ratio of mica nano powder, Tris buffer and dopamine hydrochloride in S1 is 1 g: 10-100 mL: 1.9-3 g.

[0012] As a further solution of the present invention: the mass ratio of component 1, boric acid and xylene in S2 is 30:6-10:250-500.

[0013] As a further solution of the present invention: the preparation method of silicone rubber comprises the following steps:

[0014] A1: Add octamethylcyclotetrasiloxane and tetramethyltetravinylcyclotetrasiloxane into a reactor, remove water for 1-2 hours at -0.2~-0.1MPa, 40-50℃, add tetramethylammonium hydroxide silicon alkoxide and decamethyltetrasiloxane, continue to remove water for 1-2 hours, and carry out first-stage reaction, second-stage reaction and third-stage reaction in a nitrogen atmosphere at normal pressure to obtain methyl vinyl silicone rubber;

[0015] A2: Add methyl vinyl silicone rubber and chloroform into a reaction kettle, stir evenly, add 3-chloroperoxybenzoic acid, keep warm at 30-40℃ for 12-15h, precipitate with methanol, wash and dry to obtain silicone rubber.

[0016] As a further scheme of the present invention: the first-stage reaction in A1 is specifically as follows: the heating rate is 5-10°C / min, the temperature is raised to 100-120°C, and the temperature is kept for reaction for 1-3h; the second-stage reaction is specifically as follows: the heating rate is 5-10°C / min, the temperature is raised to 150-160°C, and the temperature is kept for reaction for 1-3h; the third-stage reaction is specifically as follows: the heating rate is 5-10°C / min, the temperature is raised to 160-170°C, and the temperature is kept for reaction for 2-4h at a vacuum degree of -0.2 to -0.1MPa.

[0017] As a further embodiment of the present invention, the mass ratio of octamethylcyclotetrasiloxane, tetramethyltetravinylcyclotetrasiloxane, tetramethylammonium hydroxide siliconate and decamethyltetrasiloxane in A1 is 200-300:35-100:0.03-0.05:0.2-0.5.

[0018] As a further solution of the present invention: the mass ratio of methyl vinyl silicone rubber, chloroform and 3-chloroperoxybenzoic acid in A2 is 5g:100-200mL:3-4g.

[0019] As a further embodiment of the present invention: the vulcanizing agent is dicumyl peroxide.

[0020] A high-performance flame-retardant and heat-insulating mica material for use in the electronics field and in the electronics field.

[0021] Beneficial effects of the present invention:

[0022] (1) The present application first reacts mica nanopowder with dopamine hydrochloride. Dopamine undergoes a self-polymerization reaction in a weak alkaline aerobic environment to generate polydopamine, which adheres to the surface of the mica nanopowder. The polydopamine contains polar groups such as hydroxyl groups and amino groups, which react with the mica nanopowder to produce covalent and non-covalent effects, thereby obtaining component one. The phenolic hydroxyl groups on the surface of the polydopamine react with boric acid to obtain modified mica. The modified mica prepared in the present application is added to silicone rubber as a filler, which not only effectively improves the flame retardant and heat insulating properties of silicone rubber, but also the organic modification of mica improves its dispersion uniformity in the organic matrix, thereby effectively improving the mechanical properties of the material. The present application also prepares a new type of silicone rubber, which utilizes the fact that the Si-O bond energy of silicone rubber itself is much greater than the bond energy of a general CC bond, and the bond length is also longer than the CC bond length, to obtain a silicone rubber that is cold-resistant, heat-resistant, and thermally stable. A small amount of methylvinyl is introduced into the side chain of the silicone rubber, and the unsaturated molecular structure gives it excellent heat aging resistance, weathering aging resistance, and ozone resistance. The silicone rubber has a helical molecular configuration, the molecular chain is highly flexible, and the intermolecular interaction force is weak, giving the material good resilience. Under the action of the vulcanizing agent, the system forms a three-dimensional network structure, which makes it difficult for the macromolecular chains to have relative slippage, improves the interaction force between the polymer material chains, and increases the tensile strength. The modified mica prepared in the present application is used in combination with silicone rubber to prepare a material with excellent mechanical properties and flame retardant and heat-insulating properties.

[0023] (2) The mica material prepared by adding modified mica in the present application burns during use. The inert gas generated during the combustion process can dilute the concentration of the combustion gas or prevent oxygen from diffusing to the burning surface of the silicone rubber. During the heat absorption process of the modified mica, the temperature of the polymer is reduced, the strength of the ceramic layer after combustion is enhanced, and heat is prevented from being transferred to the depth of the silicone rubber. In addition, the modification of mica effectively increases the temperature required for the combustion of the material and the thermal decomposition temperature, so that the internal temperature of the material does not reach the temperature required for combustion, thereby achieving the purpose of flame retardancy and heat insulation of the material.

[0024] (3) The silicone rubber and modified mica prepared in this application are used in combination to improve the fire retardancy of the mica material by slowing down the rate of combustible gas generation, improving the high-temperature stability of the mica material, and increasing the strength of the ceramic material obtained from the combustion residue. After the mica material is burned, there will be a ceramic residual layer on the surface. This ceramic residual layer has the function of blocking the transfer and reaction of heat, oxygen and combustibles, thereby inhibiting the continued combustion. The addition of modified mica can not only promote the formation and stability of the ceramic residual layer, but also increase the quality and strength of the ceramic residual layer, and reduce the temperature required for ceramicization. The boric acid in the modified mica of this application is organically combined with the mica to adjust the sintering reaction of the ceramic body, reduce the trend of volume reduction after ablation, and effectively avoid the problem of excessive shrinkage of the ceramic body during the sintering process, which leads to cracks in the ceramic surface. DETAILED DESCRIPTION

[0025] The following will be described clearly and completely in conjunction with the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Example 1

[0026] The preparation method of modified mica comprises the following steps:

[0027] S1: 30 g of mica nanopowder and 300 mL of Tris buffer were added to a reaction bottle and dispersed evenly, 57 g of dopamine hydrochloride was added, dispersed evenly, stirred at room temperature for 6 h, washed, dried, and ground to obtain component 1;

[0028] S2: Add 30g of component 1, 6g of boric acid and 250g of xylene into a reaction kettle, stir evenly, heat to 100°C, reflux for 1h, cool, filter, wash and dry to obtain modified mica. Example 2

[0029] The preparation method of modified mica comprises the following steps:

[0030] S1: 30 g of mica nanopowder and 1000 mL of Tris buffer were added to a reaction bottle and dispersed evenly, 70 g of dopamine hydrochloride was added and dispersed evenly, stirred at room temperature for 9 h, washed, dried and ground to obtain component 1;

[0031] S2: Add 30g of component 1, 8g of boric acid and 350g of xylene into a reaction kettle, stir evenly, heat to 110°C, reflux for 2h, cool, filter, wash and dry to obtain modified mica. Example 3

[0032] The preparation method of modified mica comprises the following steps:

[0033] S1: 30 g of mica nanopowder and 3000 mL of Tris buffer were added to a reaction bottle and dispersed evenly, 90 g of dopamine hydrochloride was added and dispersed evenly, stirred at room temperature for 12 h, washed, dried and ground to obtain component 1;

[0034] S2: Add 30g of component 1, 10g of boric acid and 500g of xylene into a reaction kettle, stir evenly, heat to 110°C, reflux for 3h, cool, filter, wash and dry to obtain modified mica. Example 4

[0035] The preparation method of silicone rubber comprises the following steps:

[0036] A1: 300g octamethylcyclotetrasiloxane and 100g tetramethyltetravinylcyclotetrasiloxane were added into the reactor, and water was removed at -0.1MPa, 50℃, for 2h, and 0.05g tetramethylammonium hydroxide silicon alkoxide and 0.5g decamethyltetrasiloxane were added, and water was removed for 2h. In a nitrogen atmosphere at normal pressure, the temperature was increased at a rate of 5℃ / min, the temperature was increased to 100℃, and the temperature was kept for 3h; the second-stage reaction was specifically: the temperature was increased at a rate of 5℃ / min, the temperature was increased to 150℃, and the temperature was kept for 1h; the third-stage reaction was specifically: the temperature was increased at a rate of 5℃ / min, the temperature was increased to 160℃, and the vacuum was -0.1MPa for 3h to obtain methyl vinyl silicone rubber;

[0037] A2: Add 200g of methyl vinyl silicone rubber and 4000mL of chloroform into a reaction kettle, stir evenly, add 120g of 3-chloroperbenzoic acid, keep warm at 30℃ for 12h, precipitate with methanol, wash and dry to obtain silicone rubber. Example 5

[0038] A high-performance flame-retardant heat-insulating mica material comprises the following raw materials in percentage by weight: 30% of the modified mica prepared in Example 1, 0.5% of dicumyl peroxide, and 69.5% of the silicone rubber prepared in Example 4. Example 6

[0039] A high-performance flame-retardant heat-insulating mica material comprises the following raw materials in percentage by weight: 30% of the modified mica prepared in Example 2, 0.5% of dicumyl peroxide, and 69.5% of the silicone rubber prepared in Example 4. Example 7

[0040] A high-performance flame-retardant heat-insulating mica material comprises the following raw materials in percentage by weight: 30% of the modified mica prepared in Example 3, 0.5% of dicumyl peroxide, and 69.5% of the silicone rubber prepared in Example 4.

[0041] Comparative Example 1

[0042] The preparation method of modified mica comprises the following steps:

[0043] S1: 30 g of mica nanopowder and 300 mL of Tris buffer were added to a reaction bottle and dispersed evenly, 57 g of dopamine hydrochloride was added, dispersed evenly, stirred at room temperature for 6 h, washed, dried, and ground to obtain component 1;

[0044] S2: Add 30g of component 1, 6g of boric acid and 250g of xylene into a reaction kettle, stir evenly, heat to 100°C, reflux for 1h, cool, filter, wash and dry to obtain modified mica.

[0045] Comparative Example 2

[0046] The preparation method of silicone rubber comprises the following steps:

[0047] A1: Add 300g octamethylcyclotetrasiloxane and 100g tetramethyltetravinylcyclotetrasiloxane into the reactor, remove water for 2h at -0.1MPa and 50℃, add 0.05g tetramethylammonium hydroxide silicon alkoxide and 0.5g decamethyltetrasiloxane, continue to remove water for 2h, and heat up to 100℃ at a rate of 5℃ / min in a nitrogen atmosphere at normal pressure, and keep the temperature for 3h; the second-stage reaction is specifically as follows: heating up to 150℃ at a rate of 5℃ / min, and keeping the temperature for 1h; the third-stage reaction is specifically as follows: heating up to 160℃ at a rate of 5℃ / min, and reacting for 3h at a vacuum degree of -0.1MPa to obtain silicone rubber.

[0048] Comparative Example 3

[0049] Compared with Example 5, only the modified mica prepared in Example 1 is replaced by the modified mica prepared in Comparative Example 1 in equal amount, and the other components and proportions are completely consistent with those in Example 5.

[0050] Comparative Example 4

[0051] Compared with Example 5, only the silicone rubber prepared in Example 4 is replaced by the silicone rubber prepared in Comparative Example 2 in equal amount, and the other components and proportions are completely consistent with those in Example 5.

[0052] Comparative Example 5

[0053] Compared with Example 5, only the silicone rubber prepared in Example 4 is replaced by the silicone rubber prepared in Comparative Example 2 in equal amount, and the modified mica prepared in Example 1 is replaced by the modified mica prepared in Comparative Example 1 in equal amount. The other components and proportions are exactly the same as those in Example 5.

[0054] Performance Testing

[0055] The raw materials of Examples 5-7 and Comparative Examples 3-5 were weighed according to weight percentage, and the following steps were performed respectively: the silicone rubber was placed on a SK-110 double-roll plastic (rubber) refining machine (manufactured by Shanghai Kechuang Rubber and Plastic Machinery Equipment Co., Ltd.) for mixing, and modified mica and a vulcanizing agent diisopropylbenzene peroxide were added thereto, and the mixture was mixed evenly at room temperature, and the mixture was placed on a flat vulcanizer (manufactured by Shanghai Light Industry Machinery Co., Ltd., China), and vulcanized for 10 minutes at a temperature of 180° C. to prepare 1 mm, 2 mm and 3 mm specimens required for the experiment; and the following related performance tests were performed:

[0056] (1) Oxygen index: According to ASTM D2863-77, the test was carried out using the HC-2 oxygen index instrument produced by Nanjing Jiangning Analytical Instrument Factory. The sample size was 100 mm × 65 mm × 3 mm. The test results are shown in Table 1.

[0057] (2) Vertical combustion (UL-94): According to ASTM D625-77 standard, the test was carried out using the CZF-1 vertical combustion instrument produced by Nanjing Jiangning Analytical Instrument Factory. The sample size was 127 mm × 12.7 mm × 3 mm. The test results are shown in Table 1.

[0058] (3) Mechanical properties: According to GB2951.6-82 standard, the tensile strength and elongation at break of the samples were tested using a DSC-5000 universal material testing machine produced by Tsushima Corporation of Japan. The tensile speed was 50 mm / min. The test results are shown in Table 1.

[0059] (4) Mechanical properties of fired ceramic layer: The sample was fired at 1100°C for 30 min in a muffle furnace. The three-point bending strength and impact strength of the fired ceramic body were tested according to GB / T1449-2005 and GB / T1843-2008. The test speed was 5 mm / min. The test results are shown in Table 1.

[0060] (5) Solvent resistance: 1 g of the sample was placed in 50 mL of toluene solution and placed at 25 °C for 120 h. The mass change Δm before and after placement was measured and the mass loss rate was calculated. The test results are shown in Table 1.

[0061] (6) Ablation linear shrinkage: Measure the length of the ceramic sample and calculate the ablation linear shrinkage according to the following formula:

[0062] η=[(L0-L) / L0]×100%

[0063] Wherein, η is the linear shrinkage rate of ceramic sample during sintering, %; L0 is the length of sample before sintering, mm; L is the length of sample before sintering, mm.

[0064] Table 1: Statistical table of performance test data of Examples 4-7 and Comparative Examples 3-5

[0065]

[0066] It can be seen from Table 1 that the high-performance flame-retardant and heat-insulating mica material prepared in the present application has high flame-retardant and heat-insulating properties and excellent mechanical properties.

[0067] The above is a detailed description of an embodiment of the present invention, but the content is only a preferred embodiment of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A high-performance flame-retardant and heat-insulating mica material, characterized in that: The raw materials include the following weight percentages: 20-40% modified mica, 0.5-1% vulcanizing agent, and the remainder silicone rubber; The preparation method of the modified mica comprises the following steps: S1: Add mica nanopowder and Tris buffer into a reaction bottle and disperse evenly, add dopamine hydrochloride, disperse evenly, stir at room temperature for 6-12 hours, wash, dry and grind to obtain component 1; S2: Add component 1, boric acid and xylene into a reaction kettle, stir evenly, heat to 100-110°C, reflux for 1-3h, cool, filter, wash and dry to obtain modified mica; The preparation method of the silicone rubber comprises the following steps: A1: Add octamethylcyclotetrasiloxane and tetramethyltetravinylcyclotetrasiloxane into a reactor, remove water for 1-2 hours at -0.2~-0.1MPa, 40-50℃, add tetramethylammonium hydroxide silicon alkoxide and decamethyltetrasiloxane, continue to remove water for 1-2 hours, and carry out first-stage reaction, second-stage reaction and third-stage reaction in a nitrogen atmosphere at normal pressure to obtain methyl vinyl silicone rubber; A2: Add methyl vinyl silicone rubber and chloroform into a reaction kettle, stir evenly, add 3-chloroperoxybenzoic acid, keep warm at 30-40℃ for 12-15h, precipitate with methanol, wash and dry to obtain silicone rubber.

2. A high-performance flame-retardant heat-insulating mica material according to claim 1, characterized in that: The addition ratio of mica nanopowder, Tris buffer and dopamine hydrochloride in S1 is 1 g: 10-100 mL: 1.9-3 g.

3. A high-performance flame-retardant heat-insulating mica material according to claim 1, characterized in that: The mass ratio of component 1, boric acid and xylene in S2 is 30:6-10:250-500.

4. The high-performance flame-retardant heat-insulating mica material according to claim 1, characterized in that: The first stage reaction in A1 is as follows: heating rate 5-10℃ / min, heating to 100-120℃, keeping warm for 1-3h; the second stage reaction is as follows: heating rate 5-10℃ / min, heating to 150-160℃, keeping warm for 1-3h; the third stage reaction is as follows: heating rate 5-10℃ / min, heating to 160-170℃, keeping warm for 2-4h at a vacuum degree of -0.2 to -0.1MPa.

5. The high-performance flame-retardant heat-insulating mica material according to claim 1, characterized in that: The mass ratio of octamethylcyclotetrasiloxane, tetramethyltetravinylcyclotetrasiloxane, tetramethylammonium hydroxide silicon alkoxide and decamethyltetrasiloxane in A1 is 200-300:35-100:0.03-0.05:0.2-0.

5.

6. The high-performance flame-retardant heat-insulating mica material according to claim 1, characterized in that: The mass ratio of methyl vinyl silicone rubber, chloroform and 3-chloroperoxybenzoic acid in A2 is 5g:100-200mL:3-4g.

7. The high-performance flame-retardant heat-insulating mica material according to claim 1, characterized in that: The curing agent is dicumyl peroxide.

8. Application of the high-performance flame-retardant and heat-insulating mica material according to claim 1 in the field of electronics.

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