Mica composition, mica tube and preparation method and application thereof

Abstract

The application relates to the technical field of insulating materials, and particularly discloses a mica material composition, a mica tube and a preparation method and application thereof. The mica material composition provided by the application comprises the following components in parts by weight: 75-85 parts of mica powder, 35-55 parts of polyethylene, 45-55 parts of silicon powder and 25-35 parts of organic silica gel; the application also provides a mica tube prepared by using the mica material composition, and a preparation method of the mica tube, which comprises the following steps: extruding the mica material composition at an extrusion temperature of 170-190 DEG C, and then air-cooling at 20-30 DEG C for greater than or equal to 20 min to obtain a mica tube preform; and through drying, the mica tube is obtained. The mica tube is prepared by extruding the mica material composition, the mica tube is seamless, the mica tube has good insulation at room temperature and good high-temperature fire resistance, and can meet the use requirements of an electric shock rod or a waterproof sleeve tube insulating layer.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrical insulation materials, in particular to a mica material composition, a mica tube and a preparation method and application thereof. BACKGROUND

[0002] The mica tube is a hard plastic tubular material made of mica, which has excellent thermal insulation performance and mechanical strength, and is often used to make electrical-grade rods or waterproof sleeve insulating layers in various household appliances, electric motors, electric furnaces and other machines and equipment.

[0003] The existing manufacturing method of the mica tube is to immerse mica paper into an organic chemical binder, and after the binder is dried, the mica paper is rolled, dried and shaped to obtain the mica tube. However, the mica tube made by the above rolling process has gaps at the connection, which seriously affects the normal insulation performance of the mica tube. In addition, since the mica paper has poor porcelainization effect at a temperature above 600℃, the high-temperature fire resistance and insulation of the mica tube cannot be guaranteed. SUMMARY

[0004] In order to improve the normal insulation and high-temperature fire resistance of the mica tube, the present application provides a mica material composition, a mica tube and a preparation method and application thereof.

[0005] In a first aspect, the present application provides a mica material composition, which adopts the following technical solution:

[0006] A mica material composition, comprising the following components by weight: 75-85 parts of mica powder, 35-55 parts of polyethylene, 45-55 parts of silicon powder and 25-35 parts of organic silicone glue.

[0007] The present application provides a mica material composition composed of mica powder, high-temperature insulation material (polyethylene, silicon powder) and flexible material (organic silicone glue), so that the mica material composition has excellent fire resistance and insulation; the mica tube made of the mica material composition has good porcelainization effect at a high temperature above 600℃, so it has excellent normal insulation and high-temperature fire resistance, and can meet the use requirements of electrical-grade rods or waterproof sleeve insulating layers.

[0008] In this application, the polyethylene molecular chain contains a large number of methane groups, which gives its surface a non-polar characteristic, allowing its insulation performance to remain stable even at high temperatures. Silica powder is a micro-powder prepared from natural quartz or fused quartz through a series of processing steps, possessing advantages such as good temperature resistance and high insulation. The basic structural unit of silicone rubber is composed of silicon-oxygen linkages, with side chains linked to various other organic groups via silicon atoms. Therefore, silicone rubber contains both "organic groups" and "inorganic structures," a unique structure that gives it excellent adhesion and toughness, as well as excellent high-temperature insulation. Therefore, this application, by adding polyethylene, silica powder, and silicone rubber to mica powder and controlling the amount of each substance within the aforementioned range, obtains a mica composition that produces mica tubes with excellent normal-temperature insulation and high-temperature fire resistance.

[0009] In this application, "mica tube can be vitrified" means that the mica tube is opaque and dense, and has excellent fireproof, fire-resistant and insulating properties.

[0010] Preferably, the mica composition comprises the following components in parts by weight: 78-83 parts mica powder, 35-50 parts polyethylene, 48-55 parts silica powder, and 25-35 parts silicone.

[0011] In one specific implementation, the mica powder may be present in the following weight proportions: 75 parts, 78 parts, 80 parts, 83 parts, or 85 parts.

[0012] In one specific implementation, the polyethylene may be expressed in parts by weight of: 35 parts, 40 parts, 45 parts, or 50 parts.

[0013] Or 55 copies.

[0014] In one specific implementation, the silicon micropowder can be in the following weight proportions: 45 parts, 58 parts, 50 parts, 52 parts, or 55 parts.

[0015] In one specific implementation, the silicone rubber may be in the following weight parts: 25, 30 or 35 parts.

[0016] More preferably, the mica composition comprises the following components in parts by weight: 80 parts mica powder, 40 parts polyethylene, 50 parts silica powder, and 30 parts silicone.

[0017] Preferably, the density of the polyethylene is 0.94-0.96 g / cm³. 3 The polyethylene with the above-mentioned density is high-density polyethylene, compared to polyethylene with a density of 0.910-0.925 g / cm³. 3 Low-density polyethylene (LDPE) has superior high-temperature resistance compared to high-density polyethylene (HDPE).

[0018] A method for preparing a mica composition is as follows: the components are mixed and stirred at a stirring speed of 600-1000 r / min for 80-120 min to obtain the mica composition.

[0019] Secondly, this application provides a mica tube obtained by extrusion molding of the mica material composition.

[0020] The mica tube of this application is prepared by extrusion molding. Compared with the rolling process in related technologies, the mica tube prepared by extrusion molding is seamless, and the room temperature insulation and high temperature fire resistance of the mica tube are superior.

[0021] In this application, through experimental investigation, it was found that when the amount of mica powder added to the mica material composition is less than 75 parts, the fire resistance and insulation properties of the mica tube are poor; when the amount of mica powder added to the mica material composition is greater than 85 parts, the mica tube is prone to powder shedding during the production process. When the amount of polyethylene added is less than 35 parts, the mica tube will break during extrusion; when the amount of polyethylene added is greater than 55 parts, the uniformity of the mica material composition is poor, resulting in poor insulation and fire resistance of the mica tube; when the amount of silica powder added is less than 45 parts, the insulation performance of the mica tube is slightly poor; when the amount of silica powder added is greater than 55 parts, the prepared mica tube is prone to powder shedding; when the amount of silicone rubber added is less than 25 parts, the viscosity of the mica material composition is low, and the fire resistance and insulation properties of the prepared mica tube are poor; when the amount of silicone rubber added is greater than 35 parts, the mica tube cannot be cured and molded. Therefore, by controlling the amount of each component added in the mica material composition within the above-mentioned range, this application can ensure the uniformity and stability of the mica material composition, and the resulting mica tube has excellent insulation and high-temperature fire resistance, and the surface is uniform and smooth, without cracking, powdering or other phenomena.

[0022] Thirdly, this application provides a method for preparing a mica tube.

[0023] A method for preparing a mica tube includes the following steps: extruding the mica material composition at an extrusion temperature of 170-190°C, and then air-cooling it at 20-30°C for ≥20 min to obtain a mica tube preform; and drying it to obtain the mica tube.

[0024] This application provides a method for preparing mica tubes, which involves extruding a mica material composition using an extrusion device to obtain the mica tube. Through experimental investigation, this application found that in the above-mentioned method for preparing mica tubes, when the extrusion temperature is <170℃, the mica tube cannot be solidified; when the extrusion temperature is >190℃, surface cracking of the mica tube preform occurs; when the air-cooling temperature is below 20℃, the mica tube preform deforms; and when the air-cooling temperature is above 30℃, cracks appear on the surface of the mica tube preform.

[0025] In this application, the mica material composition is air-cooled after extrusion, and the air-cooling process can prevent the mica tube from getting damp and cracking.

[0026] In one specific implementation, the extrusion temperature can be 170°C, 180°C, or 190°C.

[0027] In one specific implementation, the air cooling temperature can be 20°C, 25°C, or 30°C.

[0028] Preferably, the drying process adopts a two-stage drying process; the first stage drying temperature is 80-100℃ and the drying time is ≥8min; the second stage drying temperature is 150-170℃ and the drying time is ≥10min.

[0029] In this application, before the mica tube preform is dried, its surface can also be coated with a surface treatment liquid.

[0030] In one specific embodiment, the surface treatment liquid comprises the following components in parts by weight: 20 parts ceramic powder, 40 parts silica, 10 parts glass powder, and 40 parts silicone resin.

[0031] Fourthly, the application of the mica composition and mica tube provided in this application in the preparation of insulating layers for electric shock rods or waterproof sleeves.

[0032] In summary, this application has the following beneficial effects:

[0033] 1. This application uses a specific ratio of mica powder, polyethylene, silica powder and silicone to prepare a mica material composition with excellent fire resistance and electrical insulation properties; the mica tube prepared using this mica material composition has excellent room temperature insulation and high temperature fire resistance of over 900℃, which can meet the requirements for use as an insulation layer for electric shock rods or waterproof sleeves.

[0034] 2. This application provides a method for preparing mica tubes. The method adopts an extrusion molding process. By controlling the extrusion temperature within the range of 170-190℃ and the air cooling temperature within the range of 20-30℃, mica tubes with good surface properties and excellent insulation can be prepared.

[0035] 3. The mica tube provided in this application has an inner diameter of 10 mm and an outer diameter of 14 mm; its fire resistance temperature is >900℃; and its withstand voltage under normal conditions is >50 kV / mm. Detailed Implementation

[0036] In a first aspect, this application provides a mica composition comprising the following components in parts by weight: 75-85 parts mica powder, 35-55 parts polyethylene, 45-55 parts silica powder, and 25-35 parts silicone rubber; preferably, the masterbatch composition comprises the following components in parts by weight: 78-83 parts mica powder, 35-50 parts polyethylene, 48-55 parts silica powder, and 25-35 parts silicone rubber.

[0037] The preparation method of the above-mentioned mica material composition is as follows: mix the components of the mica material composition and stir at a stirring speed of 600-1000 r / min for 80-120 min to obtain the mica material composition;

[0038] Secondly, this application provides a mica tube, which is obtained by extrusion molding of a mica material composition; the outer surface of the mica tube is covered with a ceramic coating formed by a surface treatment liquid; the surface treatment liquid includes the following components in parts by weight: 20 parts of ceramic powder, 40 parts of silicon dioxide, 10 parts of glass powder and 40 parts of organosilicon resin.

[0039] The preparation method of the above surface treatment solution is as follows: mix the components of the surface treatment solution and stir at a stirring speed of 600 r / min for 80 min to obtain the surface treatment solution.

[0040] Thirdly, this application provides a method for preparing a mica tube, comprising the following steps:

[0041] (1) Extrusion molding: The mica material composition is extruded at an extrusion temperature of 170-190℃, and then air-cooled at 20-30℃ for 20-60 min to obtain a mica tube preform; then a surface treatment liquid is coated on the outer surface of the mica tube preform.

[0042] (2) Drying: A two-stage drying process is used to dry the mica tubes. In the two-stage drying process, the first stage drying temperature is 80-100℃ and the drying time is ≥8min; the second stage drying temperature is 150-170℃ and the drying time is ≥10min.

[0043] In the embodiments of this application, the mica powder was purchased from Lingshou County Baofeng Mica Processing Co., Ltd.; the polyethylene was HDPE 5000S with a density of 0.94-0.96 g / cm³. 3The following materials were purchased: 1. Silica powder from Yanshan Petrochemical; 2. Silicone powder from Anhui Gree New Material Technology Co., Ltd.; 3. Organosilicon from Hubei Xin Sihai Chemical Co., Ltd.; 4. Aluminum nitride powder, model AIN-H, from Liaoning Desheng Special Ceramics Manufacturing Co., Ltd.; 5. Fumed silica from Shouguang Changtai New Material Co., Ltd.; 6. Glass powder (1500 mesh) from Hebei Wensheng New Material Technology Co., Ltd.; 7. CS-2000 amino silicone resin from Wuxi Xiano New Material Technology Co., Ltd.; 8. Other raw materials, reagents, solvents, etc., were also commercially available.

[0044] The following detailed description of this application is provided in conjunction with preparation examples, embodiments, and performance testing experiments.

[0045] Preparation Examples 1-15

[0046] Preparation Examples 1-15 each provide a mica composition, the difference between the above mica compositions being the amount of each component used in the mica composition; as shown in Table 1 below.

[0047] The preparation method of the mica composition provided in Examples 1-15 is as follows: weigh each component according to the amount added in Table 1, mix them, and stir at a speed of 700 r / min for 100 min to obtain the mica composition.

[0048] Table 1. Components and dosage of the mica compositions provided in Preparation Examples 1-15

[0049]

[0050] Comparative preparation examples 1-8

[0051] The preparation methods of Preparation Example 3 were compared with those of Preparation Examples 1-8, except for the composition and amount of the mica material composition; as shown in Table 2 below.

[0052] Table 2 compares the components and amounts of mica compositions provided in Preparation Examples 1-8.

[0053]

[0054] Examples 1-15

[0055] Examples 1-15 each provide a mica tube, the difference being that the mica material composition in the mica tube is derived from Examples 1-15.

[0056] The preparation method of the above-mentioned mica tube is as follows:

[0057] (1) Extrusion molding: The mica material composition is extruded at an extrusion temperature of 180°C and then air-cooled at 25°C for 20 min to obtain a mica tube preform; then a surface treatment liquid is applied to the outer surface of the mica tube preform.

[0058] The surface treatment liquid is prepared by mixing 20g of ceramic powder, 40g of silicon dioxide, 10g of glass powder and 40g of organosilicon resin evenly, and then stirring at a speed of 600r / min for 60min to obtain the surface treatment liquid.

[0059] (2) Drying: A two-stage drying process is used to obtain mica tubes with an inner diameter of 10 mm, an outer diameter of 14 mm, and a surface treatment liquid thickness of 0.2 mm. In the two-stage drying process, the first stage drying temperature is 90℃ and the drying time is 10 min; the second stage drying temperature is 160℃ and the drying time is 15 min.

[0060] Comparative Examples 1-8

[0061] Comparative Examples 1-8 each provide a mica tube.

[0062] Comparative Examples 1-8 were carried out according to the method of Example 3, except that the mica material composition in the mica tubes of Comparative Examples 1-8 was derived from Comparative Preparation Examples 1-8.

[0063] Examples 16-19

[0064] Examples 16-19 each provide a mica tube.

[0065] Examples 16-19 were carried out according to the method of Example 3, except that some parameters in the mica tube preparation method are shown in Table 3.

[0066] Table 3 shows some parameters in the mica tube preparation methods provided in Examples 16-19.

[0067]

[0068] Comparative Example 9

[0069] Comparative Example 9 provides a mica tube.

[0070] Comparative Example 9 was carried out according to the method of Example 3, except that the extrusion temperature in the mica tube preparation method provided in Comparative Example 9 was 160°C.

[0071] Comparative Example 10

[0072] Comparative Example 10 provides a mica tube.

[0073] Comparative Example 10 was carried out according to the method of Example 3, except that the extrusion temperature in the mica tube preparation method provided in Comparative Example 10 was 200°C.

[0074] Comparative Example 11

[0075] Comparative Example 11 provides a mica tube.

[0076] Comparative Example 11 was carried out according to the method of Example 3, except that air cooling was replaced with water cooling, the temperature was 25°C and the time was 20 minutes.

[0077] Performance testing

[0078] The physical properties and performance of the mica tubes obtained in Examples 1-19 and Comparative Examples 1-11 of this application were tested, and the results are shown in Table 4.

[0079] (1) Physical properties: including whether the mica tube is deformed, whether it has cracks, whether the surface is uniform and smooth, and whether there is white powder. Note: When the surface properties of the mica tube are poor, the fire resistance and voltage resistance related performance tests are abandoned directly, and " / " is used to indicate this in Table 4.

[0080] (2) A copper conductor is lined inside a mica tube, and copper wire is wound around the outside of the mica tube to obtain a test sample; then the test sample is subjected to room temperature voltage resistance and fire resistance tests.

[0081] ① Normal temperature withstand voltage: Place the test sample in a muffle furnace and set the temperature to 25℃; then gradually apply pressure to the conductor until the mica tube breaks down. The pressure at which it breaks down is the normal temperature withstand voltage.

[0082] ②Fire resistance: The test sample is placed in a muffle furnace and the conductor is pressurized to 25kV; then the temperature is gradually increased until the mica tube breaks down. The temperature at which the breakdown occurs is the fire resistance temperature.

[0083] Table 4. Performance test results of mica tubes in Examples 1-19 and Comparative Examples 1-11

[0084]

[0085]

[0086]

[0087] According to the test results in Table 4, the mica tubes provided in Examples 1-19 of this application have smooth surfaces, are free of cracks and powder, and have a withstand voltage of >50kV and a fire resistance of >900℃ at room temperature. This indicates that the above-mentioned mica tubes possess excellent fire resistance and high-temperature insulation properties, and can fully meet the requirements for use as insulation layers of electrode rods or boundary waterproof sleeves.

[0088] Although the mica tube obtained in Comparative Example 1 had a smooth surface, no cracks, and no powder, its fire resistance and insulation were poor due to the low mica powder content in the mica powder composition.

[0089] Comparative Example 2 shows that due to the excessively high mica powder content in the mica powder composition, the mica tubes are prone to powder shedding during the production process.

[0090] In Comparative Example 3, the mica tube broke during extrusion due to insufficient addition of polyethylene.

[0091] In Comparative Example 4, the excessive addition of polyethylene resulted in poor uniformity of the mica composition, which in turn led to lower fire resistance and insulation properties of the mica tube.

[0092] Although the mica tube obtained in Comparative Example 5 had a smooth surface, no cracks, and no powder, its insulation was poor due to the insufficient amount of silicon micropowder added.

[0093] Comparative Example 6: Due to excessive addition of silicon micropowder, the mica tube experienced powder shedding.

[0094] Comparative Example 7 shows that the mica tubes produced have poor fire resistance and insulation due to the low viscosity of the mica composition.

[0095] Comparative Example 8: Due to excessive addition of silicone, the mica tube could not be cured and formed.

[0096] Comparative Example 9 shows that the mica tube could not be cured and formed because the extrusion temperature was below 170°C.

[0097] Comparative Example 10: The surface of the mica tube cracked due to the extrusion temperature being higher than 190°C.

[0098] Comparative Example 11 used water cooling, and the resulting mica tube had surface cracks due to moisture.

[0099] The test results of Examples 1-5 show that when the amount of mica powder added in Examples 1-5 is controlled between 75-85 parts, the resulting mica tubes have a smooth surface, are free of cracks and powder, and have a room temperature withstand voltage of 51-63 kV / mm and a fire resistance temperature of 908-971℃. Further comparison reveals that when the amount of mica powder added in Examples 3-4 is controlled between 78-83 parts, the resulting mica tubes have a room temperature withstand voltage of 58-63 kV / mm (≥55 kV / mm) and a fire resistance temperature of 957-971℃ (≥950℃). Therefore, it is demonstrated that by further controlling the amount of mica powder added to between 78-83 parts in this application, the resulting mica tubes exhibit even better fire resistance and electrical insulation properties.

[0100] The test results of Examples 3 and 6-9 show that when the amount of polyethylene added in Examples 3 and 6-9 is controlled between 35-55 parts, the resulting mica tubes have a smooth surface, are free of cracks and powder, and have a room temperature voltage resistance of 53-63 kV / mm and a fire resistance temperature of 919-971℃. Further comparison reveals that when the amount of polyethylene added in Examples 3 and 6-8 is controlled between 35-50 parts, the resulting mica tubes have a room temperature voltage resistance of 59-63 kV / mm (≥55 kV / mm) and a fire resistance temperature of 952-971℃ (≥950℃). Therefore, it is demonstrated that by further controlling the amount of polyethylene added in this application between 35-50 parts, the resulting mica tubes exhibit superior fire resistance and electrical insulation properties.

[0101] The test results of Examples 3 and 10-13 show that when the amount of silicon micropowder added in Examples 3 and 10-13 is controlled between 45-55 parts, the resulting mica tubes have a smooth surface, are free of cracks and powder, and have a room temperature withstand voltage of 54-63 kV / mm and a fire resistance temperature of 937-971℃. Further comparison reveals that when the amount of silicon micropowder added in Examples 3 and 7-8 is controlled between 48-55 parts, the resulting mica tubes have a room temperature withstand voltage of 57-53 kV / mm (≥55 kV / mm) and a fire resistance temperature of 958-971℃ (≥950℃). Therefore, it is demonstrated that by further controlling the amount of silicon micropowder added to between 48-55 parts, the mica tubes obtained in this application exhibit superior fire resistance and electrical insulation properties.

[0102] The test results of Examples 3 and 14-15 show that when the amount of silicon micropowder added in Examples 3 and 14-15 is controlled between 25 and 35 parts, the resulting mica tube has a smooth surface, no cracks, and no powder. Its room temperature withstand voltage is 58-63 kV / mm, and its fire resistance temperature is 952-971℃. The mica tube has excellent fire resistance and electrical insulation.

[0103] The test results of Examples 3 and 16-19 show that by controlling the base temperature between 170-190℃ and the air cooling temperature between 20-30℃, the mica tubes obtained in this application have good fire resistance and electrical insulation. Their room temperature withstand voltage is 60-63kv / mm and their fire resistance temperature is 955-971℃.

[0104] In summary, the mica tube provided in this application has excellent thermal insulation properties and can fully meet the requirements for use as an insulation layer for electric shock rods or waterproof sleeves.

[0105] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A mica tube, characterized in that, The method for preparing the mica tube includes the following steps: extruding the mica material composition at an extrusion temperature of 170-190℃, and then air-cooling it at 20-30℃ for ≥20 minutes to obtain a mica tube preform; coating the surface of the mica tube preform with a surface treatment liquid, and drying it to obtain the mica tube. The mica composition comprises the following components in parts by weight: 78-83 parts mica powder, 35-50 parts polyethylene, 48-55 parts silica powder, and 25-35 parts silicone. The surface treatment liquid comprises the following components in parts by weight: 20 parts ceramic powder, 40 parts silicon dioxide, 10 parts glass powder, and 40 parts organosilicon resin. The drying process employs a two-stage drying process; the first stage drying temperature is 80-100℃, and the drying time is ≥8min; the second stage drying temperature is 150-170℃, and the drying time is ≥10min.

2. The mica tube according to claim 1, wherein the mica material composition comprises the following components in parts by weight: 80 parts mica powder, 40 parts polyethylene, 50 parts silica powder and 30 parts silicone.

3. The mica tube according to any one of claims 1-2, characterized in that, The density of the polyethylene is 0.94-0.96 g / cm³. 3 .

4. The application of the mica tube as described in any one of claims 1-3 in the preparation of the insulating layer of an electric shock rod or a waterproof sleeve.

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