A high-temperature resistant halogen-free flame-retardant insulating multi-layer composite material

Abstract

The present invention discloses a high-temperature resistant halogen-free flame-retardant insulating multi-layer composite material, belonging to the technical field of composite materials. This composite material is prepared with mica tape as the dielectric material, polyimide film and glass cloth as the reinforcing materials, modified silicone pressure-sensitive adhesive as the adhesive, and in combination with a halogen-free flame retardant; the high-temperature resistant halogen-free flame-retardant insulating multi-layer composite material prepared with three kinds of base materials has good comprehensive properties and can be widely applied to the winding insulation, gasket insulation and filling insulation of electrical equipment. The flame-retardant system in the present invention has a small smoke generation amount during combustion and does not generate corrosive and toxic gases. According to the test results, the multi-layer composite material has good insulation performance, flame retardancy, tensile strength and flexibility, and the temperature has little influence on its insulation performance, and it still has high insulation performance at 200 °C.

Description

Technical Field

[0001] The present invention belongs to the technical field of composite materials, and particularly relates to a high-temperature resistant halogen-free flame-retardant insulating multi-layer composite material. Background Art

[0002] An insulating structure is a structure formed by combining the same or several insulating materials through a specific process, and mainly involves inter-turn insulation, ground insulation, outer insulation, and phase-to-phase insulation. At present, for most large and medium-sized high-voltage motor insulation systems, when using silicone glass cloth reinforced mica tape or epoxy diphenyl ether glass cloth reinforced mica tape, it seriously affects the normal and hot state dielectric loss of stator coils, shortens the electrothermal aging life of coil insulation, and harmful and toxic gases are generated during the stator insulation treatment and insulation curing (high-temperature drying) processes, which are harmful to operators and the environment, and the safety in the fields of insulating products such as winding insulation, gasket insulation, and filling insulation is relatively poor. Summary of the Invention

[0003] The purpose of the present invention is to provide a high-temperature resistant halogen-free flame-retardant insulating multi-layer composite material to solve the problem in the background art that the composite materials in the fields of insulating products such as winding insulation, gasket insulation, and filling insulation have poor high-temperature resistance during processing or application, affecting safety.

[0004] The purpose of the present invention can be achieved through the following technical solutions:

[0005] A high-temperature resistant halogen-free flame-retardant insulating multi-layer composite material, which successively comprises a polyimide film, a mica tape, and a glass cloth from top to bottom; the multi-layer composite material uses the mica tape as a dielectric material, the polyimide film and the glass cloth as reinforcing materials, a modified silicone pressure-sensitive adhesive as an adhesive, and is prepared by cooperating with a halogen-free flame retardant; both sides of the polyimide film, the mica tape, and the glass cloth are coated with the halogen-free flame retardant, and the polyimide film, the mica tape, and the glass cloth coated with the halogen-free flame retardant are bonded through the modified silicone pressure-sensitive adhesive; the halogen-free flame retardant comprises the following raw materials in weight percentages: 55-65% of a triazine compound, 25-35% of an epoxy anhydride resin, 0.8-1.5% of a leveling agent, 0.8-1.5% of an antioxidant, and 8-20% of a flame retardant auxiliary agent; compared with inorganic flame-retardant powder coatings, the amount of the flame retardant auxiliary agent used in the present invention is less, and it is an organic flame retardant, which does not affect the mechanical properties of the powder coating. After special surface treatment and adding 15%-30% of the halogen-free flame retardant, it is easy to disperse in the insulating material and does not precipitate, having a good flame retardant effect. The triazine compound is a mixture of a triazinetrione compound and a triazinamine compound in a mass ratio of 3:7.

[0006] The halogen-free flame retardant is prepared through the following steps:

[0007] Put the raw materials of each component into a mixing tank, pre-mix for 15 minutes, then extrude and tablet on an extruder. The extrusion temperature in zone 1 is 110 °C and in zone 2 is 130 °C. Then crush the tablets and pulverize them. The fine powder obtained by passing the coarse powder through a 300-mesh rotary sieve is the final powder coating, which is a halogen-free flame retardant.

[0008] The structural formula of the triazinetrione compound is as follows:

[0009]

[0010] The structural formula of the triazinetriamine compound is as follows:

[0011]

[0012] Furthermore, the flame retardant aid consists of the following weight percentages: 50 wt% of polyphenylene sulfide resin GF00, 25 wt% of a plasticizer, and 25 wt% of a coupling agent SG-Si171;

[0013] Dissolve the coupling agent in water to prepare a 10 - 30% solution, then add other components, stir in a homogenizer for 3 - 5 hours, mix evenly, place in a vacuum drying oven and dry at 105 °C and -0.09 MPa for 4 - 6 hours, and pulverize to obtain the flame retardant aid.

[0014] Furthermore, the plasticizer is one of glyceryl triacetate, tributyl citrate, and tri-n-butyl acetylcitrate.

[0015] Furthermore, the modified silicone pressure-sensitive adhesive is prepared by the following steps:

[0016] Step 1: Add the nano powder and silane coupling agent A151 to a mixed solution of anhydrous ethanol and toluene, perform ultrasonic treatment at a temperature of 45 °C for 30 - 40 minutes, filter and dry to obtain the pretreated nano powder;

[0017] Step 2: Then stir and mix the pretreated nano powder and the silicone pressure-sensitive adhesive, and add benzoyl peroxide to obtain the modified silicone pressure-sensitive adhesive. The dosage ratio of the nano powder, silane coupling agent A151 to the mixed solution of anhydrous ethanol and toluene is 1 g : 1 g : 20 mL; the volume ratio of anhydrous ethanol to toluene in the mixed solution of anhydrous ethanol and toluene is 6.5 : 3.5; the mass ratio of the pretreated nano powder to the silicone pressure-sensitive adhesive is 3 : 5; the addition amount of benzoyl peroxide is 8% of the sum of the masses of the pretreated nano powder and the silicone pressure-sensitive adhesive, and the silicone pressure-sensitive adhesive is polydimethylsiloxane; the addition of the nano powder can better maintain a strong electrical strength.

[0018] Furthermore, the nano powder is nano SiC and nano Al 2 O3 It is mixed in a mass ratio of 1.5:1; the average particle size of nano-SiC is 30 nm; the average particle size of nano-Al 2 O 3 is 30 nm.

[0019] Furthermore, the multi-layer composite material is prepared by the following steps:

[0020] Apply a halogen-free flame retardant on both sides of the polyimide film, mica tape and glass cloth respectively, then apply a modified silicone pressure-sensitive adhesive on both sides of the mica tape coated with the halogen-free flame retardant, and apply a modified silicone pressure-sensitive adhesive on one side of the glass cloth coated with the halogen-free flame retardant. Then place the polyimide film, mica tape, and glass cloth in order from top to bottom for mechanical lamination. After lamination, a high-temperature resistant halogen-free flame retardant insulating multi-layer composite material is obtained after heat treatment.

[0021] Furthermore, the thickness of the polyimide film is 0.025 mm, the thickness of the mica tape is 0.060 mm, and the thickness of the glass cloth is 0.030 mm; the coating amount of the halogen-free flame retardant: 60 - 100 mg / m 2 ; the coating amount of the modified silicone pressure-sensitive adhesive: 20 - 35 mg / m 2 .

[0022] Furthermore, the pressure of mechanical lamination is 10 kN, and the working beat is 12 times / minute.

[0023] Furthermore, the temperature of heat treatment is 80 ± 5 °C.

[0024] Advantages of the present invention:

[0025] The present invention provides a high-temperature resistant halogen-free flame retardant insulating multi-layer composite material, which is formed by laminating a polyimide film, a glass cloth, and a mica tape with a modified organic pressure-sensitive adhesive and a halogen-free flame retardant. In the applications of winding insulation, gasket insulation, and filling insulation of electrical equipment, the polyimide film, glass cloth, and mica tape in the composite material have better thermal conductivity than the prior art after lamination; compared with the prior art silicone glass cloth reinforced mica tape, it has excellent insulation performance. In the prior art, the glass cloth in the silicone glass cloth reinforced mica tape belongs to an inorganic material with relatively low electrical properties. The composite material prepared by the present invention adds a polyimide film as one of the reinforcing materials, and the volume resistivity of the prepared composite material exceeds 1.2×10 12 Ω·m at 200 °C, and while maintaining a strong electrical strength, the resistivity at 200 °C only drops by one order of magnitude; it does not affect the high-temperature resistance performance of the composite material.

[0026] In the present invention, after polyimide film, glass cloth and mica tape are compounded by a modified organic pressure-sensitive adhesive and a halogen-free flame retardant, the high-temperature resistance performance is better, the winding temperature rise can be reduced at the same insulation thickness; the motor size can be reduced and the motor weight can be lightened under the same temperature rise condition; the loss can be reduced, thereby improving the motor efficiency. More prominently, it can be seen from the test results that the tensile strength of the composite material can be better maintained by using the three substrates, which means that the probability of being damaged under the same winding conditions is greatly reduced, the product quality is improved, and the winding speed can be increased when permitted by the equipment, further improving the production efficiency and meeting the use requirements of insulation products such as winding insulation, gasket insulation and filling insulation.

[0027] In the flame retardant system of the present invention, the smoke generation amount during combustion is small, and no corrosive and toxic gases are generated. According to the test results, the multi-layer composite material has good insulation performance, flame retardancy, tensile strength and flexibility, and the temperature has little influence on its insulation performance, and it still has high insulation performance at 200 °C. When applied to the fields of insulation products such as winding insulation, gasket insulation and filling insulation, it can better endow electrical equipment with good reliability and safety. Specific embodiments

[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative work shall fall within the protection scope of the present invention.

[0029] Example 1

[0030] This example provides a halogen-free flame retardant, which is prepared by the following steps:

[0031] Weigh the raw materials according to the weight percentage: 50 wt% of polyphenylene sulfide resin GF00, 25 wt% of plasticizer and 25 wt% of coupling agent SG-Si171; dissolve the coupling agent in water to prepare a 10% solution, then add other components, stir in a homogenizer for 3 h, mix evenly, put it into a vacuum drying oven and dry at 105 °C and -0.09 MPa for 4 h, and then pulverize to obtain the flame retardant auxiliary agent; the plasticizer is triacetin.

[0032] Put the raw materials in weight percentages into the mixing tank: 65% of triazine compounds, 25% of epoxy anhydride resin (model: JF-9955 Jufeng Materials), 1% of leveling agent (PV88 from German Deshenli Chemical), 1% of antioxidant (antioxidant 1010 from German BASF), and 8% of flame retardant aid; premix for 15 min, then extrude and tablet on an extruder. The extrusion temperature in zone 1 is 110 °C and in zone 2 is 130 °C. Then crush the tablets and pulverize them. The fine powder obtained by passing the coarse powder through a 300-mesh sieve by a cyclone sieve is the final powder coating, which is a halogen-free flame retardant. Among them, the particle size of the epoxy anhydride resin is ≤ 30 μm.

[0033] Example 2

[0034] This example provides a halogen-free flame retardant, which is prepared by the following steps:

[0035] Weigh the raw materials according to weight percentages: 50 wt% of polyphenylene sulfide resin GF00, 25 wt% of plasticizer, and 25 wt% of coupling agent SG-Si171; dissolve the coupling agent in water to prepare a 20% solution, then add other components, stir in a homogenizer for 4 h, mix evenly, put it into a vacuum drying oven and dry at 105 °C and -0.09 MPa for 5 h, and pulverize to obtain the flame retardant aid; the plasticizer is tributyl citrate.

[0036] Put the raw materials in weight percentages into the mixing tank: 55% of triazine compounds, 35% of epoxy anhydride resin (model: JF-9955 Jufeng Materials), 1% of leveling agent (PV88 from German Deshenli Chemical), 1% of antioxidant (antioxidant 1010 from German BASF), and 8% of flame retardant aid; premix for 15 min, then extrude and tablet on an extruder. The extrusion temperature in zone 1 is 110 °C and in zone 2 is 130 °C. Then crush the tablets and pulverize them. The fine powder obtained by passing the coarse powder through a 300-mesh sieve by a cyclone sieve is the final powder coating, which is a halogen-free flame retardant. Among them, the particle size of the epoxy anhydride resin is ≤ 30 μm.

[0037] Example 3

[0038] This example provides a halogen-free flame retardant, which is prepared by the following steps:

[0039] Weigh the raw materials according to weight percentages: 50 wt% of polyphenylene sulfide resin GF00, 25 wt% of plasticizer, and 25 wt% of coupling agent SG-Si171; dissolve the coupling agent in water to prepare a 30% solution, then add other components, stir in a homogenizer for 5 h, mix evenly, put it into a vacuum drying oven and dry at 105 °C and -0.09 MPa for 6 h, and pulverize to obtain the flame retardant aid; the plasticizer is acetyl tributyl citrate.

[0040] Put the raw materials in weight percentages into a mixing tank: 55% of triazine compounds, 25% of epoxy anhydride resin (model: JF-9955 Jufeng Materials), 1.5% of leveling agent (PV88 from German Deshenli Chemical), 1.5% of antioxidant (antioxidant 1010 from German BASF), and 17% of flame retardant additive; premix for 15 min, then extrude and tablet on an extruder. The extrusion temperature in zone 1 is 110 °C and in zone 2 is 130 °C. Then crush the tablets and pulverize them. The fine powder obtained by passing the coarse powder through a 300-mesh sieve of a cyclone sieve is the final powder coating, which is a halogen-free flame retardant. Among them, the particle size of the epoxy anhydride resin is ≤30 μm.

[0041] Example 4

[0042] This example provides a modified silicone pressure-sensitive adhesive, which is prepared by the following steps:

[0043] Step 1: Add nano powder and silane coupling agent A151 into a mixed solution of anhydrous ethanol and toluene, and perform ultrasonic treatment for 40 min at a temperature of 45 °C to obtain pretreated nano powder; the nano powder is nano SiC and nano Al 2 O 3 mixed in a mass ratio of 1.5:1; the average particle size of nano SiC is 30 nm; nano Al 2 O 3 has an average particle size of 30 nm; the dosage ratio of nano powder, silane coupling agent A151 to the mixed solution of anhydrous ethanol and toluene is 1 g:1 g:20 mL; the volume ratio of anhydrous ethanol to toluene in the mixed solution of anhydrous ethanol and toluene is 6.5:3.5;

[0044] Step 2: Then stir and mix the pretreated nano powder and the silicone pressure-sensitive adhesive, and add benzoyl peroxide to obtain the modified silicone pressure-sensitive adhesive; the mass ratio of the rice powder body to the silicone pressure-sensitive adhesive is 3:5; the addition amount of benzoyl peroxide is 8% of the sum of the masses of the pretreated nano powder and the silicone pressure-sensitive adhesive. The silicone pressure-sensitive adhesive is polydimethylsiloxane.

[0045] Comparative Example 1

[0046] This example provides a silicone pressure-sensitive adhesive. Compared with Example 4, this comparative example does not add pretreated nano powder, and the remaining raw materials and the preparation process are the same as those in Example 4.

[0047] Example 5

[0048] This example provides a multi-layer composite material, which is prepared by the following steps:

[0049] Coat both sides of the polyimide film, mica tape (model: 501), and fiberglass cloth with the halogen-free flame retardant prepared in Example 3. Then, coat both sides of the mica tape coated with the halogen-free flame retardant with the modified silicone pressure-sensitive adhesive prepared in Example 4, and coat one side of the fiberglass cloth coated with the halogen-free flame retardant with the modified silicone pressure-sensitive adhesive. Then, place the polyimide film, mica tape, and fiberglass cloth in order from top to bottom for mechanical lamination. The pressure for mechanical lamination is 10 kN, and the working rhythm is 12 times per minute. After lamination, the heat treatment temperature is 80 ± 5 °C. After heat treatment, a high-temperature halogen-free flame retardant insulating multi-layer composite material is obtained; the thickness of the polyimide film is 0.025 mm, the thickness of the mica tape is 0.060 mm, and the thickness of the fiberglass cloth is 0.030 mm; the coating amount of the halogen-free flame retardant: 60 mg / m 2 ; the coating amount of the modified silicone pressure-sensitive adhesive: 35 mg / m 2 .

[0050] Example 6

[0051] This example provides a multi-layer composite material, which is prepared by the following steps:

[0052] Coat both sides of the polyimide film, mica tape (model: 501), and fiberglass cloth with the halogen-free flame retardant prepared in Example 2. Then, coat both sides of the mica tape coated with the halogen-free flame retardant with the modified silicone pressure-sensitive adhesive prepared in Example 4, and coat one side of the fiberglass cloth coated with the halogen-free flame retardant with the modified silicone pressure-sensitive adhesive. Then, place the polyimide film, mica tape, and fiberglass cloth in order from top to bottom for mechanical lamination. The pressure for mechanical lamination is 10 kN, and the working rhythm is 12 times per minute. After lamination, the heat treatment temperature is 80 ± 5 °C. After heat treatment, a high-temperature halogen-free flame retardant insulating multi-layer composite material is obtained; the thickness of the polyimide film is 0.025 mm, the thickness of the mica tape is 0.060 mm, and the thickness of the fiberglass cloth is 0.030 mm; the coating amount of the halogen-free flame retardant: 80 mg / m 2 ; the coating amount of the modified silicone pressure-sensitive adhesive: 25 mg / m 2 .

[0053] Example 7

[0054] This example provides a multi-layer composite material, which is prepared by the following steps:

[0055] Coat both sides of a polyimide film, mica tape (model: 501), and glass cloth with the halogen-free flame retardant prepared in Example 1. Then, coat both sides of the mica tape coated with the halogen-free flame retardant with the modified silicone pressure-sensitive adhesive prepared in Example 4, and coat one side of the glass cloth coated with the halogen-free flame retardant with the modified silicone pressure-sensitive adhesive. Then, place the polyimide film, mica tape, and glass cloth in order from top to bottom for mechanical lamination. The pressure for mechanical lamination is 10 kN, and the working rhythm is 12 times per minute. After lamination, the heat treatment temperature is 80 ± 5 °C. After heat treatment, a high-temperature halogen-free flame-retardant insulating multi-layer composite material is obtained; the thickness of the polyimide film is 0.025 mm, the thickness of the mica tape is 0.060 mm, and the thickness of the glass cloth is 0.030 mm; the coating amount of the halogen-free flame retardant: 100 mg / m 2 ; the coating amount of the modified silicone pressure-sensitive adhesive: 20 mg / m 2 .

[0056] Comparative Example 2

[0057] Compared with Example 7, in this comparative example, the modified silicone pressure-sensitive adhesive is replaced with the silicone pressure-sensitive adhesive prepared in Comparative Example 1, and the other raw materials and preparation process are the same as those in Example 7.

[0058] Comparative Example 3

[0059] Compared with Comparative Example 2, in this comparative example, the polyimide film is replaced with glass cloth, and the other raw materials and preparation process are the same as those in Comparative Example 2.

[0060] Perform performance tests on Examples 5 - 7 and Comparative Examples 2 - 3. The results are shown in Table 1:

[0061] Table 1

[0062]

[0063]

[0064] As can be seen from the test results in Table 1, compared with the products prepared in Comparative Examples 2 - 3, the composite materials prepared in the examples of the present invention have higher electrical strength, and the volume resistivity at 200 °C exceeds 1.0 × 10 12 Ω·m, having excellent insulation performance, and the resistivity at 200 °C only drops by one order of magnitude, indicating that the high temperature has a relatively small impact on the volume resistivity, further demonstrating the high-temperature resistance of the composite material that can be used at 200 °C.

[0065] The prepared composite material has good halogen-free flame retardant effect and has reached the flame retardant grade V-O. The composite material can automatically extinguish within a very short time after leaving the flame, which plays a good flame retardant effect on the potential fire hazards that may occur in electrical equipment. In addition, no halogen-containing flame retardant is added separately in the system of this composite material, and it does not contain toxic and polluting substances, and will not release gases harmful to humans and the environment after combustion, and its flame retardant performance is good.

[0066] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprises", "comprising" or any other variation thereof is intended to cover a non-exclusive inclusion, such that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device.

[0067] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A high-temperature resistant halogen-free flame-retardant insulating multi-layer composite material, characterized in that, in the applications of wrapping insulation, gasket insulation, and filling insulation of electrical machinery equipment, from top to bottom are polyimide film, mica tape, and glass cloth in sequence; both sides of the polyimide film, mica tape, and glass cloth are coated with halogen-free flame retardant, and the polyimide film, mica tape, and glass cloth coated with halogen-free flame retardant are bonded through a modified silicone pressure-sensitive adhesive; the halogen-free flame retardant includes the following raw materials by weight percentage: 55-65% of triazine compounds, 25-35% of epoxy anhydride resin, 0.8-1.5% of leveling agent, 0.8-1.5% of antioxidant, 8-20% of flame retardant aid; the triazine compound is a mixture of triazinone compound and triazine triamine compound in a mass ratio of 3:7; The thickness of the polyimide film is 0.025 mm, the thickness of the mica tape is 0.060 mm, and the thickness of the glass cloth is 0.030 mm; the coating amount of the halogen-free flame retardant: 60-100 mg / m 2 ; the coating amount of the modified silicone pressure-sensitive adhesive: 20-35 mg / m 2 ; the halogen-free flame retardant is prepared through the following steps: Pre-mix the raw materials for 15 min, then extrude and tablet on an extruder, the extrusion temperature in zone one is 110 °C, in zone two is 130 °C, and pulverize through a 300-mesh sieve to obtain the halogen-free flame retardant; The structural formula of the triazinone compound is as follows: The structural formula of the triazine triamine compound is as follows:

2. A high-temperature resistant halogen-free flame-retardant insulating multi-layer composite material according to claim 1, characterized in that, the flame retardant aid is composed of the following by weight percentage: 50 wt% of polyphenylene sulfide resin GF00, 25 wt% of plasticizer, and 25 wt% of coupling agent SG-Si 171; dissolve the coupling agent SG-Si 171 in water to prepare a 10-30% solution, then add other components, stir in a homogenizer for 3-5 h, mix evenly, place in a vacuum drying oven and dry at 105 °C and -0.09 MPa for 4-6 h, and pulverize to obtain the flame retardant aid.

3. A high-temperature resistant halogen-free flame-retardant insulating multi-layer composite material according to claim 2, characterized in that, the plasticizer is one of glyceryl triacetate, tributyl citrate, and tri-n-butyl acetylcitrate.

4. A high-temperature resistant halogen-free flame-retardant insulating multi-layer composite material according to claim 1, characterized in that, the modified silicone pressure-sensitive adhesive is prepared through the following steps: Step one: Add nano powder and silane coupling agent A151 into a mixed solution of anhydrous ethanol and toluene, perform ultrasonic treatment at a temperature of 45 °C for 30-40 min, filter and dry to obtain pretreated nano powder; the dosage ratio of nano powder, silane coupling agent A151 to the mixed solution of anhydrous ethanol and toluene is 1 g:1 g:20 mL; the volume ratio of anhydrous ethanol to toluene in the mixed solution of anhydrous ethanol and toluene is 6.5:3.5; Step two: Then stir and mix the pretreated nano powder and the silicone pressure-sensitive adhesive, and add benzoyl peroxide to obtain the modified silicone pressure-sensitive adhesive; the mass ratio of the pretreated nano powder to the silicone pressure-sensitive adhesive is 3:

5.

5. A high-temperature resistant halogen-free flame-retardant insulating multi-layer composite material according to claim 4, characterized in that, The nano powder is a mixture of nano-SiC and nano-Al 2 O 3 mixed in a mass ratio of 1.5:1; the average particle size of nano-SiC is 30 nm; the average particle size of nano-Al 2 O 3 is 30 nm.

6. A high-temperature resistant halogen-free flame-retardant insulating multi-layer composite material according to claim 1, characterized in that, the multi-layer composite material is prepared through the following steps: Apply a halogen-free flame retardant to both sides of the polyimide film, mica tape, and glass cloth. Then, apply a modified silicone pressure-sensitive adhesive to both sides of the mica tape coated with the halogen-free flame retardant, and apply a modified silicone pressure-sensitive adhesive to one side of the glass cloth coated with the halogen-free flame retardant. Then, place the polyimide film, mica tape, and glass cloth in order from top to bottom for mechanical lamination. After lamination, a high-temperature resistant halogen-free flame retardant insulating multi-layer composite material is obtained after heat treatment.

7. A high-temperature resistant halogen-free flame retardant insulating multi-layer composite material according to claim 6, characterized in that, the pressure of mechanical lamination is 10 kN, and the working beat is 12 times / minute.

8. A high-temperature resistant halogen-free flame retardant insulating multi-layer composite material according to claim 6, characterized in that, the temperature of heat treatment is 80 ± 5 °C.

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