Highly efficient flame-retardant and heat-conducting polyamide composite material, its preparation method and application

Abstract

The present invention discloses a polyamide composite material with high-efficiency flame retardancy and heat conduction, as well as its preparation method and application. The polyamide composite material is made from the following raw materials: polyamide resin, glass fiber grafted with heteropolyacid, boron nitride modified with DDP or its derivatives and / or DOPOMA, antioxidant, compatibilizer and lubricant. The preparation method includes: uniformly mixing the polyamide resin, boron nitride modified with DDP or its derivatives and / or DOPOMA, antioxidant, compatibilizer and lubricant, then performing melt blending with the glass fiber grafted with heteropolyacid, and then hot pressing and molding to obtain the polyamide composite material. By surface modification of the glass fiber and boron nitride, the present invention can greatly improve the flame retardancy of the composite material, improve the interfacial interaction between the heat conduction material and the polyamide matrix, more easily form a heat conduction network structure, the prepared composite material has a higher thermal conductivity, and at the same time takes into account excellent flame retardancy and heat conduction capabilities.

Description

Technical Field

[0001] The present invention relates to a polyamide composite material, and particularly to a polyamide composite material with high-efficiency flame retardancy and heat conduction, its preparation method and application, belonging to the technical field of polymer modification and processing. Background Art

[0002] Polyamide materials have many advantages such as high strength, wear resistance, and corrosion resistance, and are widely used in the automotive, electronic, and electrical industries. At present, with the trend of "small, light, and thin" of electronic components, the integration degree, power, and frequency of equipment are also getting higher and higher. Inevitably, a large amount of heat accumulates during high-frequency continuous operation. It will be a difficult problem that cannot be underestimated and needs to be solved urgently to quickly, timely, and efficiently dissipate the heat accumulated inside the equipment. The low thermal conductivity of polyamide limits its application, and polyamide materials are prone to cause fires when facing high temperatures, high humidity, etc. in actual use, posing a great potential safety hazard. Therefore, endowing polyamide materials with high-efficiency flame retardancy and heat conduction performance is an urgent problem to be solved.

[0003] Adding flame retardants such as phosphorus-based flame retardants, nitrogen-based flame retardants, intumescent flame retardants, etc. and heat-conducting fillers such as alumina, magnesia, zinc oxide, aluminum nitride, boron nitride, silicon carbide, carbon fiber, metal fiber, etc. is the most common method for preparing flame-retardant and heat-conducting polyamide materials. However, adding a large amount of flame retardants and heat-conducting fillers will cause a decline in the mechanical properties of the materials, thus limiting their application in many fields.

[0004] Hexagonal boron nitride (hBN) is a two-dimensional flake material with a graphite-like lattice structure, showing high in-plane thermal conductivity, excellent electrical insulation and dielectric properties, and high thermal and chemical stability. Therefore, it is highly favored in the preparation of high-thermal-conductivity and high-flame-retardant polymer composites. However, hBN has disadvantages such as poor dispersion and weak interfacial interaction in the polymer matrix, which also limits its large-scale development in the preparation of high-performance polymer-based thermal-conductivity composites.

[0005] The invention patent with the publication number CN106336654A provides a heat-conducting polyamide material, which contains 35% - 65% of polyamide, 15% - 40% of heat-conducting filler, 8% - 15% of main flame retardant, 2.0% - 6.0% of auxiliary flame retardant, 0.1% - 0.5% of antioxidant, 0.1% - 0.5% of lubricant, 2.5% - 5.0% of inorganic filler, and 0.1% - 1.0% of rare earth oxide; a heat-conducting polyamide with a high thermal conductivity and a low linear expansion coefficient is obtained and applied to the LED housing. However, this invention uses a bromine-based flame retardant system, with a large amount of flame retardant added, and it is easy to leave free small-molecule bromine residues, which is likely to accelerate the degradation of the resin matrix in a long-term heat contact environment and affect the service life of the product.

[0006] Therefore, it is of great significance to study a highly efficient flame-retardant and heat-conducting nylon composite material and its preparation method. Summary of the Invention

[0007] The main object of the present invention is to provide a highly efficient flame-retardant and heat-conducting polyamide composite material and its preparation method, so as to overcome the deficiencies of the prior art.

[0008] Another object of the present invention is also to provide the application of the highly efficient flame-retardant and heat-conducting polyamide composite material.

[0009] To achieve the foregoing invention objects, the technical solutions adopted by the present invention include:

[0010] The embodiment of the present invention provides a highly efficient flame-retardant and heat-conducting polyamide composite material, which is prepared from the following raw materials: polyamide resin, glass fiber grafted with heteropolyacid, boron nitride modified with DDP or its derivatives and / or DOPO derivative DOPOMA, antioxidant, compatibilizer and lubricant.

[0011] In some embodiments, the polyamide composite material is prepared from the following raw materials calculated by weight percentage: 46-67% of polyamide resin, 5-30% of glass fiber grafted with heteropolyacid, 5-30% of boron nitride modified with DDP or its derivatives and / or DOPO derivative DOPOMA, 0.5-1% of antioxidant, 1-2% of compatibilizer and 0.5-1% of lubricant.

[0012] The embodiment of the present invention also provides a preparation method of a highly efficient flame-retardant and heat-conducting polyamide composite material, which includes:

[0013] Mix polyamide resin, boron nitride modified with DDP or its derivatives and / or DOPO derivative DOPOMA, antioxidant, compatibilizer and lubricant evenly, and then add the glass fiber grafted with heteropolyacid to a kneading device for melt blending, and then hot press molding to obtain the highly efficient flame-retardant and heat-conducting polyamide composite material.

[0014] The embodiment of the present invention also provides a highly efficient flame-retardant and heat-conducting polyamide composite material prepared by the foregoing preparation method.

[0015] The embodiment of the present invention also provides the application of the foregoing highly efficient flame-retardant and heat-conducting polyamide composite material in the fields of preparing the outer packaging of electronic appliances or the base of new energy vehicle batteries, etc.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] 1) The preparation method of the high-efficiency flame-retardant and heat-conducting polyamide composite material provided by the present invention can greatly improve the flame-retardant performance of the composite material by surface modification of glass fiber and boron nitride, improve the interfacial interaction between the heat-conducting material and the polyamide matrix, more easily form a heat-conducting network structure, enhance the heat-conducting performance of the composite material, and the prepared composite material has a higher heat-conductivity coefficient, while taking into account excellent flame-retardant and heat-conducting capabilities; moreover, the preparation method of the present invention is simple and the reaction conditions are mild, which is suitable for large-scale industrial production;

[0018] 2) The polyamide composite material prepared by the present invention can be used in places such as the outer packaging of electronic appliances and the base of new energy vehicle batteries, which have requirements for good mechanical strength, excellent flame-retardant and heat-conducting performance. Description of the Drawings

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments recorded in the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0020] Figure 1 It is the FT-IR diagram of the glass fiber grafted with phosphomolybdonickel heteropolyacid prepared in a typical embodiment of the present invention. Detailed Embodiments

[0021] In view of the defects of the prior art, the inventors of this case will focus on solving problems such as poor dispersion of heat-conducting fillers in the matrix and weak interfacial interaction. After long-term research and a large number of practices, the technical solution of the present invention has been proposed. It mainly grafts inorganic flame retardant heteropolyacid onto the surface of glass fiber through chemical reaction, bonds organic flame retardants DDP or its derivatives, DOPO derivative DOPOMA, etc. onto the surface of hBN, and at the same time solves the problem of low heat-conductivity coefficient of polyamide composite materials. The following will clearly and completely describe the technical solution of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0022] A high-efficiency flame-retardant and heat-conducting polyamide composite material provided by one aspect of the embodiments of the present invention is prepared from the following raw materials calculated by weight percentage: 46-67% of polyamide resin, 5-30% of glass fiber grafted with heteropolyacid, 5-30% of boron nitride modified with DDP or its derivatives and / or DOPO derivative DOPOMA, 0.5-1% of antioxidant, 1-2% of compatibilizer, and 0.5-1% of lubricant.

[0023] In some embodiments, the heteropolyacid-grafted glass fiber is obtained by chemically grafting a heteropolyacid onto the surface of the glass fiber. Specifically, it is obtained by modifying the glass fiber with a silane coupling agent and grafting an inorganic flame retardant heteropolyacid. Among them, the heteropolyacids used include Keggin-type heteropolyacids, preferably including any one or a combination of two or more of nickel phosphomolybdate (PMo 11 Ni·nH2O), phosphotungstic acid, phosphomolybdic acid, silicotungstic acid, etc., but not limited thereto.

[0024] Among them, the addition amount of the glass fiber modified with a silane coupling agent and grafted with a heteropolyacid is 5-30 wt% of the total mass of the composite material.

[0025] Among them, the diameter of the glass fiber used is 6-13 μm, and the types of glass fiber can include any one or a combination of two of non-alkali continuous glass fiber, chopped glass fiber, etc., but not limited thereto.

[0026] In some embodiments, the boron nitride modified with DDP or its derivatives and / or DOPO derivative DOPOMA is prepared by using boron nitride, modifying it with a silane coupling agent and bonding an organic flame retardant DDP (DDP is [(6-oxo-6H-dibenzo[c,e][1,2]oxaphosphorin-6-yl)methyl]succinic acid, molecular formula C 17 H 15 O6P), or a DDP derivative, or a DOPO derivative DOPOMA (9,10-dihydro-9-oxa-10-phosphaphenanthrene-succinic acid), etc., to the surface of the boron nitride. In the present invention, a silane coupling agent is used to perform surface modification and grafting treatment on the boron nitride, and then an organic flame retardant such as DDP or its derivatives and DOPO derivative DOPOMA is bonded to the surface of the boron nitride through a carboxyl ring-opening reaction to improve the compatibility between hBN and the polyamide matrix and enhance the thermal conductivity of the material.

[0027] Among them, the addition amount of the boron nitride surface-modified with a silane coupling agent and bonded with a flame retardant such as DDP or its derivatives and DOPO derivative DOPOMA is 5-30 wt% of the total mass of the composite material.

[0028] Furthermore, the particle size of the boron nitride is about 1-2 μm. In the present invention, high-thermal-conductivity boron nitride is used, and after being compounded with the rod-shaped material glass fiber, it plays a synergistic role to form a good thermal conduction path and enhance the thermal conductivity of the material.

[0029] In some embodiments, the polyamide resin includes any one or a combination of two of heat-resistant polyamides such as PA56, PA6, etc., but not limited thereto.

[0030] Further, the antioxidant includes any one or a combination of two of phenolic antioxidants, thioester antioxidants, etc., and specifically may be antioxidant 1010 (pentaerythritol tetrakis [β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate]), antioxidant DSTP (distearyl thiodipropionate), etc., but is not limited thereto.

[0031] Further, the compatibilizer may be AX8900, but is not limited thereto.

[0032] Further, the lubricant includes any one or a combination of two or more of molybdenum disulfide, liquid paraffin, and polytetrafluoroethylene micropowder, etc., but is not limited thereto.

[0033] In some embodiments, the limiting oxygen index of the highly flame-retardant and thermally conductive polyamide composite material is 32.4 - 42.8%, the flame retardancy rating is V-0 grade, and the thermal conductivity at room temperature is 0.95 - 2.32 W / (m·K -1 )

[0034] Another aspect of the embodiments of the present invention provides a preparation method of a highly flame-retardant and thermally conductive polyamide composite material, which mainly includes:

[0035] Modifying glass fiber with a silane coupling agent, and then grafting a heteropolyacid-based flame retardant onto the surface of the glass fiber through an amino ring-opening reaction; performing surface modification and grafting treatment on boron nitride with a silane coupling agent, and then bonding an organic flame retardant DDP or its derivative, DOPO derivative DOPOMA, etc. onto the surface of boron nitride through a carboxyl ring-opening reaction to obtain boron nitride modified with DDP or its derivative and / or DOPO derivative DOPOMA on the surface; and,

[0036] Adding the glass fiber grafted with heteropolyacid and the boron nitride filler modified with DDP or its derivative and / or DOPO derivative DOPOMA into polyamide resin, and performing melt blending by a kneader and hot pressing to prepare a polyamide composite material (also referred to as "polyamide-glass fiber-boron nitride flame-retardant and thermally conductive composite material").

[0037] In some embodiments, the preparation method includes: drying raw materials such as boron nitride modified with DDP or its derivative and / or DOPO derivative DOPOMA, polyamide resin, antioxidant, compatibilizer, lubricant, etc., and mixing them in proportion to obtain a mixed base material, adding the glass fiber grafted with heteropolyacid into a kneader, performing melt blending by the kneader, and hot pressing the obtained melt to prepare the highly flame-retardant and thermally conductive polyamide composite material.

[0038] In some embodiments, the silane coupling agent may include any one or a combination of two of KH550, KH560, etc., but is not limited thereto.

[0039] In some embodiments, the method for preparing the heteropolyacid-grafted glass fiber includes: first, modifying the glass fiber with a silane coupling agent, and then grafting the heteropolyacid onto the surface of the glass fiber through an amino ring-opening reaction to obtain the heteropolyacid-grafted glass fiber.

[0040] In some more specific embodiments, the method for preparing the heteropolyacid-grafted glass fiber further includes:

[0041] Hydrolyzing the silane coupling agent in an acetic acid solution with a pH value of 4.0 - 5.0 for 1 - 2 h to obtain a hydrolysis solution, and immersing the pretreated glass fiber in the hydrolysis solution for 30 - 60 min to obtain a modified glass fiber;

[0042] Immersing the modified glass fiber in the heteropolyacid solution at room temperature for 8 - 9 h for an amino ring-opening reaction to graft the heteropolyacid onto the surface of the glass fiber, thereby obtaining the heteropolyacid-grafted glass fiber.

[0043] Further, the preparation method further includes: calcining the glass fiber at 300 - 350 °C for 2 - 3 h, and then calcining it at 400 - 450 °C for 1 - 2 h to obtain a pretreated glass fiber.

[0044] Among them, in some more specific embodiments, taking the phosphomolybdic nickel heteropolyacid as an example, the specific steps for preparing the phosphomolybdic nickel heteropolyacid-grafted glass fiber are as follows:

[0045] (1) Synthesizing the phosphomolybdic nickel heteropolyacid: Prepared from nickel nitrate, sodium molybdate, and phosphoric acid through acidification reflux and ether extraction.

[0046] (2) Pretreating the glass fiber: Calcining the glass fiber in a muffle furnace at 300 - 350 °C for 2 - 3 h, and then calcining it at 400 - 450 °C for 1 - 2 h. The calcined glass fiber is washed 3 times with ethanol and deionized water respectively, and dried overnight in a vacuum oven at 80 °C.

[0047] (3) Treating the glass fiber with the coupling agent: Using a co-solvent of methanol and distilled water. After hydrolyzing the silane coupling agent in an acetic acid solution with a pH value of 4.0 - 5.0 for 1 - 2 h, the glass fiber obtained in step (2) is immersed in the hydrolyzed silane solution for 30 - 60 minutes and dried at 110 °C for 30 min.

[0048] (4) Grafting the heteropolyacid onto the glass fiber: Immersing the modified glass fiber obtained in step (3) into the phosphomolybdic nickel heteropolyacid solution obtained in step (1), and stirring vigorously for 8 - 9 h. After washing with deionized water, it is dried in a vacuum oven.

[0049] Among them, 2 - 6% of flame retardant elements such as P, Mo, and Ni are introduced into the phosphomolybdic nickel heteropolyacid-grafted glass fiber.

[0050] The mechanism of graft modification of glass fiber by heteropolyacid in the present invention lies in that: when the heteropolyacid molecule decomposes in advance at a lower temperature to generate H2O and absorb heat, and at a higher temperature, it oxidatively decomposes to generate an oxygen-containing acid with viscosity. It can both cover the surface of the matrix to form a liquid film and accelerate carbonization on the surface of the matrix to form a carbon layer. Both substances can isolate the internal matrix from the external heat and combustible gases. Phosphorus element is a flame retardant element, and during combustion, the phosphorus compound decomposes to generate a liquid film of phosphoric acid to protect the polymer matrix. Nickel element is beneficial to protecting the matrix and promoting carbonization, thus forming a more stable carbon layer. Molybdenum and tungsten elements have good smoke suppression effects.

[0051] In some embodiments, the preparation method of the boron nitride modified by DDP or its derivatives and / or DOPO derivative DOPOMA includes: first, surface modification graft treatment of boron nitride is carried out with a silane coupling agent, and then DDP or its derivatives and / or DOPO derivative DOPOMA is bonded to the surface of boron nitride through a carboxyl ring-opening reaction to obtain the boron nitride modified by DDP or its derivatives and / or DOPO derivative DOPOMA.

[0052] In some more specific embodiments, the preparation method of the boron nitride modified by DDP or its derivatives and / or DOPO derivative DOPOMA further includes:

[0053] Mix and stir the solution containing the silane coupling agent with boron nitride for 5 - 6 h to obtain boron nitride grafted with the silane coupling agent on the surface;

[0054] Immerse the boron nitride grafted with the silane coupling agent on the surface in an organic solution containing DDP or its derivatives and / or DOPO derivative DOPOMA for 22 - 24 h, and heat to 80 - 100 °C for 22 - 24 h for carboxyl ring-opening reaction, so that DDP and / or DOPO or its derivatives are bonded to the surface of boron nitride to obtain the boron nitride modified by DDP or its derivatives and / or DOPO derivative DOPOMA.

[0055] Among them, the preparation method of DOPO derivative DOPOMA is:

[0056] In a three-necked flask equipped with a stirrer, a thermometer, and a reflux condenser, add toluene, tetrahydrofuran, DOPO, and maleic acid, stir and heat, and reflux. Cool to room temperature and filter, collect the filter cake, and dry overnight to obtain DOPOMA.

[0057] Among them, in some more specific embodiments, taking DDP as an example, the specific steps for preparing DDP-modified boron nitride are as follows:

[0058] (1) Add ethanol, deionized water, and a silane coupling agent (such as KH560) into a beaker and stir at 70 °C for 1 h.

[0059] (2) Add BN particles into the solution obtained in step (1), continuously stir for 5 - 6 h, filter and dry for 8 h to obtain KH560 - BN.

[0060] (3) Add the KH560 - BN obtained in step (2) into an organic solvent containing the flame retardant DDP, soak for 22 - 24 h, stir magnetically, heat in a water bath to 80 - 100 °C, react for 22 - 24 h, filter the mixed solution by suction, wash the filter residue with ethanol 3 - 5 times, and freeze - dry to obtain boron nitride with the flame retardant DDP bonded to its surface.

[0061] Among them, 5 - 10% of the P flame - retardant element is introduced into the boron nitride modified by DDP.

[0062] The reasons for the present invention to select boron nitride and glass fiber are as follows: Boron nitride is a two - dimensional sheet - structured heat - conducting material, which is prone to stacking and uneven dispersion; the compounding of rod - shaped glass fiber and lamella can improve the thermal conductivity of the composite material at low filling amounts; in addition, the two inorganic fillers are absolutely non - flammable, can cover the surface of the composite material, block the contact between oxygen and combustibles, block the combustion path, and play the function of flame retardancy of the filler.

[0063] Furthermore, by surface - modifying glass fiber and boron nitride, the present invention can greatly improve the flame - retardant performance of the composite material, improve the interfacial interaction between the heat - conducting material and the polyamide matrix. The carboxyl group in the flame retardant DDP or DOPOMA molecule can react with the N - H bond on the polyamide molecular chain to form a salt, enhance the interfacial interaction between boron nitride and the polyamide matrix, and enhance the thermal conductivity of the composite material.

[0064] In some embodiments, the preparation method further includes: first drying the polyamide resin at 70 °C - 80 °C for 4 - 6 h, and then uniformly mixing it with boron nitride modified by DDP or its derivatives and / or DOPO derivative DOPOMA, antioxidant, compatibilizer, and lubricant.

[0065] In some embodiments, the temperature of the melt blending is 260 - 280 °C, and the rotation speed used is 50 - 80 rpm.

[0066] In some embodiments, the temperature of the hot - pressing molding is 270 - 285 °C, and the time is 8 - 10 min.

[0067] In some more specific embodiments, the preparation method of the highly flame - retardant and heat - conducting polyamide composite material includes the following steps:

[0068] (1) Modify the glass fiber with a silane coupling agent, and then graft the heteropolyacid-based inorganic flame retardant onto the glass fiber surface through an amino ring-opening reaction;

[0069] (2) Perform surface modification and grafting treatment on boron nitride with a silane coupling agent, and then bond organic flame retardants such as DDP or DOPOMA to the boron nitride surface through a carboxyl ring-opening reaction to obtain boron nitride modified with flame retardants such as DDP or DOPOMA on the surface;

[0070] (3) Dry the polyamide resin in a forced-air oven at 70 °C to 80 °C for 4 to 6 hours.

[0071] (4) Mix the polyamide resin obtained in step (3) uniformly with boron nitride modified with flame retardants such as DDP or DOPOMA, an antioxidant, a compatibilizer, and a lubricant.

[0072] (5) Add the uniformly mixed material obtained in step (4) and the glass fiber grafted with heteropolyacid to the feeding port of a mixer according to the above ratio, and perform melt blending at 260 to 280 °C with a rotation speed of 50 to 80 rpm.

[0073] (6) Thermally press and mold the melt obtained in step (5) to prepare a polyamide-glass fiber-boron nitride flame retardant and heat-conducting composite material; the temperature for thermally press molding is 270 to 285 °C, and the time is 8 to 10 minutes.

[0074] In summary, the composite material prepared by the present invention has more uniform dispersion of fillers, is more likely to form a heat-conducting network structure, has a higher thermal conductivity of the prepared composite material, and at the same time takes into account excellent flame retardant and heat-conducting capabilities.

[0075] Another aspect of the embodiments of the present invention also provides a polyamide composite material with high-efficiency flame retardant and heat conduction prepared by any of the foregoing preparation methods.

[0076] Furthermore, another aspect of the embodiments of the present invention also provides an application of the polyamide composite material with high-efficiency flame retardant and heat conduction in the fields of preparing the outer packaging of electronic appliances or the base of new energy vehicle batteries, etc.

[0077] Among them, the polyamide composite material provided by the present invention has excellent flame retardant and heat conduction properties, and can be used as the outer packaging of electronic appliances, the base of new energy vehicle batteries, etc., that is, places with requirements for good mechanical strength, excellent flame retardant and heat conduction properties.

[0078] The technical solution of the present invention will be further described in detail below in conjunction with several preferred embodiments and accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. It should be noted that the following embodiments are intended to facilitate the understanding of the present invention, rather than limiting it in any way. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative work fall within the scope of protection of the present invention. The experimental methods without specific conditions noted in the following embodiments are usually carried out under conventional conditions or according to the conditions recommended by the manufacturer.

[0079] The preparation process of the glass fiber grafted with the flame retardant phosphomolybdic nickel heteropolyacid used in the following Example 1 is as follows:

[0080] (1) Synthesis of phosphomolybdic nickel heteropolyacid: Prepared from nickel nitrate, sodium molybdate, and phosphoric acid through acidification reflux and ether extraction.

[0081] (2) Pretreatment of glass fiber: The glass fiber is calcined in a muffle furnace at 300 °C for 3 h, and then at 400 °C for 1 h. The calcined glass fiber is washed 3 times with ethanol and deionized water respectively, and dried overnight in a vacuum oven at 80 °C.

[0082] (3) Treatment of glass fiber with coupling agent: Using a co-solvent of methanol and distilled water. After hydrolyzing the silane coupling agent KH550 in an acetic acid solution with a pH value of 4.0 for 1 h, the glass fiber obtained in step (2) is immersed in the hydrolyzed silane solution for 30 minutes and dried at 110 °C for 30 min.

[0083] (4) Grafting of heteropolyacid on glass fiber: The modified glass fiber obtained in step (3) is immersed in the phosphomolybdic nickel heteropolyacid solution obtained in step (1), and stirred vigorously for 9 h. After washing with deionized water, it is dried in a vacuum oven.

[0084] The preparation process of the glass fiber grafted with the flame retardant phosphomolybdic nickel heteropolyacid used in the following Example 2 is as follows:

[0085] (1) Synthesis of phosphomolybdic nickel heteropolyacid: Prepared from nickel nitrate, sodium molybdate, and phosphoric acid through acidification reflux and ether extraction.

[0086] (2) Pretreatment of glass fiber: The glass fiber is calcined in a muffle furnace at 350 °C for 2 h, and then at 450 °C for 1 h. The calcined glass fiber is washed 3 times with ethanol and deionized water respectively, and dried overnight in a vacuum oven at 80 °C.

[0087] (3) Coupling agent treatment of glass fiber: Use a co-solvent of methanol and distilled water. After hydrolyzing the silane coupling agent KH550 in an acetic acid solution with a pH value of 5.0 for 2 h, immerse the glass fiber obtained in step (2) in the hydrolyzed silane solution for 40 minutes, and dry it at 110 °C for 30 min.

[0088] (4) Grafting heteropolyacid onto glass fiber: Immerse the modified glass fiber obtained in step (3) into the phosphomolybdonickel heteropolyacid solution obtained in step (1), and stir vigorously for 8 h. After washing with deionized water, dry it in a vacuum oven.

[0089] The preparation process of the glass fiber grafted with the flame retardant phosphomolybdonickel heteropolyacid used in Example 3 below is as follows:

[0090] (1) Synthesis of phosphomolybdonickel heteropolyacid: Prepared from nickel nitrate, sodium molybdate, and phosphoric acid through acidification reflux and ether extraction.

[0091] (2) Pretreatment of glass fiber: Calcine the glass fiber in a muffle furnace at 330 °C for 2 h, and then calcine it at 420 °C for 2 h. Wash the calcined glass fiber with ethanol and deionized water 3 times respectively. Place it in a vacuum oven at 80 °C overnight.

[0092] (3) Coupling agent treatment of glass fiber: Use a co-solvent of methanol and distilled water. After hydrolyzing the silane coupling agent KH560 in an acetic acid solution with a pH value of 4.5 for 2 h, immerse the glass fiber obtained in step (2) in the hydrolyzed silane solution for 60 minutes, and dry it at 110 °C for 30 min.

[0093] (4) Grafting heteropolyacid onto glass fiber: Immerse the modified glass fiber obtained in step (3) into the phosphomolybdonickel heteropolyacid solution obtained in step (1), and stir vigorously for 8 h. After washing with deionized water, dry it in a vacuum oven.

[0094] The preparation process of the glass fiber grafted with the flame retardant phosphomolybdonickel heteropolyacid used in the remaining examples is basically the same as that in Example 1.

[0095] The preparation process of the boron nitride modified with the flame retardant DDP used in Example 1 below is as follows:

[0096] (1) Add ethanol, deionized water, and the silane coupling agent KH560 into a beaker, and stir at 70 °C for 1 h.

[0097] (2) Add BN particles to the solution obtained in step (1), stir continuously for 5 h, filter and dry for 8 h to obtain KH560-BN.

[0098] (3) Add the KH560-BN obtained in step (2) to an organic solvent containing the flame retardant DDP, soak for 24 h, stir magnetically, heat in a water bath to 80 °C, react for 24 h, filter the mixed solution by suction, wash the filter residue with ethanol 3-5 times, and freeze-dry to obtain boron nitride with the flame retardant DDP bonded to its surface.

[0099] The preparation process of the boron nitride modified with the flame retardant DDP used in Example 2 below is as follows:

[0100] (1) Add ethanol, deionized water, and the silane coupling agent KH560 to a beaker and stir at 70 °C for 1 h.

[0101] (2) Add BN particles to the solution obtained in step (1), stir continuously for 6 h, filter and dry for 8 h to obtain KH560-BN.

[0102] (3) Add the KH560-BN obtained in step (2) to an organic solvent containing the flame retardant DDP, soak for 22 h, stir magnetically, heat in a water bath to 100 °C, react for 22 h, filter the mixed solution by suction, wash the filter residue with ethanol 3-5 times, and freeze-dry to obtain boron nitride with the flame retardant DDP bonded to its surface.

[0103] The preparation process of the boron nitride modified with the flame retardant DDP used in Example 3 below is as follows:

[0104] (1) Add ethanol, deionized water, and the silane coupling agent KH550 to a beaker and stir at 70 °C for 1 h.

[0105] (2) Add BN particles to the solution obtained in step (1), stir continuously for 6 h, filter and dry for 8 h to obtain KH550-BN.

[0106] (3) Add the KH550-BN obtained in step (2) to an organic solvent containing the flame retardant DDP, soak for 23 h, stir magnetically, heat in a water bath to 90 °C, react for 23 h, filter the mixed solution by suction, wash the filter residue with ethanol 3-5 times, and freeze-dry to obtain boron nitride with the flame retardant DDP bonded to its surface.

[0107] The preparation process of the boron nitride modified with the flame retardant DDP used in the remaining examples is basically the same as that in Example 1.

[0108] Example 1

[0109] The high-efficiency flame-retardant and heat-conductive polyamide composite material provided by this embodiment has raw materials for preparation including glass fiber grafted with the flame retardant phosphomolybdic nickel heteropolyacid, boron nitride modified with the flame retardant DDP, polyamide resin, antioxidant, compatibilizer and lubricant. The added mass ratio is as follows: polyamide resin 47.5%, glass fiber grafted with the flame retardant phosphomolybdic nickel heteropolyacid 20%, boron nitride modified with the flame retardant DDP 30%, antioxidant 1%, compatibilizer 1% and lubricant 0.5%.

[0110] In the preparation of the above high-efficiency flame-retardant and heat-conductive polyamide composite material, the raw material polyamide is heat-resistant polyamide PA56; the antioxidant is a mixture of antioxidant 1010 and antioxidant DSTP1; the compatibilizer is AX8900; the lubricant is liquid paraffin.

[0111] The particle size of the boron nitride is about 1 - 2 μm, and it is bonded with the organic flame retardant DDP after being treated with the silane coupling agent KH560; the glass fiber is grafted with the inorganic flame retardant phosphomolybdic nickel heteropolyacid after being treated with the silane coupling agent KH550.

[0112] The preparation method of the above high-efficiency flame-retardant and heat-conductive polyamide composite material includes the following steps:

[0113] (1) Mix the polyamide resin dried at 70°C for 6 h with the boron nitride modified with the flame retardant DDP, antioxidant, compatibilizer and lubricant evenly.

[0114] (2) Add the above evenly mixed materials and the glass fiber grafted with the phosphomolybdic nickel heteropolyacid to the feeding port of the internal mixer according to the above ratio, and carry out melt blending at 280°C for 8 min, with a rotation speed of 50 rpm.

[0115] (3) Thermally press and mold the melt obtained in step (2) to obtain a polyamide - glass fiber - boron nitride flame-retardant and heat-conductive composite material; the temperature of the thermal pressing and molding is 285°C, and the time is 10 min.

[0116] Example 2

[0117] The high-efficiency flame-retardant and heat-conductive polyamide composite material provided by this embodiment has raw materials for preparation including glass fiber grafted with the flame retardant phosphomolybdic nickel heteropolyacid, boron nitride modified with the flame retardant DDP, polyamide resin, antioxidant, compatibilizer and lubricant. The added mass ratio is as follows: polyamide resin 57.5%, glass fiber grafted with the flame retardant phosphomolybdic nickel heteropolyacid 10%, boron nitride modified with the flame retardant DDP 30%, antioxidant 1%, compatibilizer 1% and lubricant 0.5%.

[0118] In the preparation of the above high-efficiency flame-retardant and heat-conductive polyamide composite material, the raw material polyamide is heat-resistant polyamide PA6; the antioxidant is antioxidant 1010; the compatibilizer is AX8900; the lubricant is molybdenum disulfide.

[0119] The particle size of the boron nitride is about 1 - 2 μm, and after surface treatment with silane coupling agent KH560, it is bonded with the organic flame retardant DDP; the glass fiber is grafted with the inorganic flame retardant phosphomolybdic nickel heteropolyacid after being treated with silane coupling agent KH550.

[0120] The preparation method of the high - efficiency flame - retardant and heat - conductive polyamide composite material comprises the following steps:

[0121] (1) Mix the polyamide resin dried at 80 °C for 6 h evenly with the boron nitride modified by the flame retardant DDP, antioxidant, compatibilizer and lubricant.

[0122] (2) Add the above - mentioned evenly - mixed materials and the glass fiber grafted with phosphomolybdic nickel heteropolyacid into the feeding port of the internal mixer according to the above ratio, and carry out melt blending at 265 °C for 8 min, with a rotation speed of 50 rpm.

[0123] (3) Thermally press - form the melt obtained in step (2) to obtain a polyamide - glass fiber - boron nitride flame - retardant and heat - conductive composite material; the temperature of thermally press - forming is 275 °C and the time is 10 min.

[0124] Example 3

[0125] The high - efficiency flame - retardant and heat - conductive polyamide composite material provided in this example has raw materials including glass fiber grafted with phosphomolybdic nickel heteropolyacid flame retardant, boron nitride modified by flame retardant DDP, polyamide resin, antioxidant, compatibilizer and lubricant, and their added mass ratios are: polyamide resin 57.5%, glass fiber grafted with phosphomolybdic nickel heteropolyacid flame retardant 20%, boron nitride modified by flame retardant DDP 20%, antioxidant 1%, compatibilizer 1% and lubricant 0.5%.

[0126] In the preparation of the above - mentioned high - efficiency flame - retardant and heat - conductive polyamide composite material, the raw material polyamide is a mixture of heat - resistant polyamides PA56 and PA6; the antioxidant is antioxidant 1010; the compatibilizer is AX8900; the lubricant is polytetrafluoroethylene micropowder.

[0127] The particle size of the boron nitride is about 1 - 2 μm, and after surface treatment with silane coupling agent KH550, it is bonded with the organic flame retardant DDP; the glass fiber is grafted with the inorganic flame retardant phosphomolybdic nickel heteropolyacid after being treated with silane coupling agent KH560.

[0128] The preparation method of the high - efficiency flame - retardant and heat - conductive polyamide composite material comprises the following steps:

[0129] (1) Mix the polyamide resin dried at 80 °C for 4 h evenly with the boron nitride modified by the flame retardant DDP, antioxidant, compatibilizer and lubricant.

[0130] (2) Add the above-mentioned uniformly mixed materials and the glass fiber grafted with phosphomolybdic nickel heteropolyacid into the feeding port of the internal mixer according to the above ratio, and melt-blend them at 260 °C for 10 min with a rotation speed of 80 rpm.

[0131] (3) Hot press the melt obtained in step (2) to prepare a polyamide-glass fiber-boron nitride flame-retardant and heat-conducting composite material; the temperature for hot pressing is 270 °C and the time is 8 min.

[0132] Example 4

[0133] The polyamide composite material with high-efficiency flame retardancy and heat conduction provided in this example has raw materials including glass fiber grafted with the flame retardant phosphomolybdic nickel heteropolyacid, boron nitride modified with the flame retardant DDP, polyamide resin, antioxidant, compatibilizer and lubricant, and their added mass ratios are: 66.5% of polyamide resin, 10% of glass fiber grafted with the flame retardant phosphomolybdic nickel heteropolyacid, 20% of boron nitride modified with the flame retardant DDP, 0.5% of antioxidant, 2% of compatibilizer and 1% of lubricant.

[0134] In the preparation of the above polyamide composite material with high-efficiency flame retardancy and heat conduction, the raw material polyamide is heat-resistant polyamide PA56; the antioxidant is antioxidant DSTP; the compatibilizer is AX8900; the lubricant is a mixture of molybdenum disulfide and liquid paraffin.

[0135] The particle size of the boron nitride is about 1-2 μm, and it is surface-treated with the silane coupling agent KH560 and then bonded with the organic flame retardant DDP; the glass fiber is treated with the silane coupling agent KH550 and then grafted with the inorganic flame retardant phosphomolybdic nickel heteropolyacid.

[0136] The preparation method of the above polyamide composite material with high-efficiency flame retardancy and heat conduction includes the following steps:

[0137] (1) Mix the polyamide resin dried at 75 °C for 5 h with the boron nitride modified with the flame retardant DDP, antioxidant, compatibilizer and lubricant uniformly.

[0138] (2) Add the above-mentioned uniformly mixed materials and the glass fiber grafted with phosphomolybdic nickel heteropolyacid into the feeding port of the internal mixer according to the above ratio, and melt-blend them at 270 °C for 8 min with a rotation speed of 50 rpm.

[0139] (3) Hot press the melt obtained in step (2) to prepare a polyamide-glass fiber-boron nitride flame-retardant and heat-conducting composite material; the temperature for hot pressing is 275 °C and the time is 8 min.

[0140] Example 5

[0141] The high-efficiency flame-retardant and heat-conductive polyamide composite material provided by this embodiment has raw materials including glass fiber grafted with the flame retardant phosphomolybdic nickel heteropolyacid, boron nitride modified with the flame retardant DDP, polyamide resin, antioxidant, compatibilizer, and lubricant. The added mass ratio is as follows: polyamide resin 66.5%, glass fiber grafted with the flame retardant phosphomolybdic nickel heteropolyacid 20%, boron nitride modified with the flame retardant DDP 10%, antioxidant 0.5%, compatibilizer 2%, and lubricant 1%.

[0142] In the preparation of the above high-efficiency flame-retardant and heat-conductive polyamide composite material, the raw material polyamide is heat-resistant polyamide PA56; the antioxidant is a mixture of antioxidant 1010 and antioxidant DSTP; the compatibilizer is AX8900; the lubricant is a mixture of molybdenum disulfide, liquid paraffin, and polytetrafluoroethylene micropowder.

[0143] The particle size of the boron nitride is about 1 - 2 μm, and after surface treatment with the silane coupling agent KH560, it is bonded with the organic flame retardant DDP; the glass fiber is grafted with the inorganic flame retardant phosphomolybdic nickel heteropolyacid after being treated with the silane coupling agent KH550.

[0144] The preparation method of the above high-efficiency flame-retardant and heat-conductive polyamide composite material includes the following steps:

[0145] (1) Mix the polyamide resin dried at 70°C for 6 h with the boron nitride modified with the flame retardant DDP, antioxidant, compatibilizer, and lubricant evenly.

[0146] (2) Add the above evenly mixed materials and the glass fiber grafted with the phosphomolybdic nickel heteropolyacid to the feeding port of the internal mixer according to the above ratio, and carry out melt blending at 280°C for 8 min with a rotation speed of 50 rpm.

[0147] (3) Hot press the melt obtained in step (2) to obtain a polyamide-glass fiber-boron nitride flame-retardant and heat-conductive composite material; the temperature of hot pressing is 285°C, and the time is 10 min.

[0148] Example 6

[0149] The high-efficiency flame-retardant and heat-conductive polyamide composite material provided by this embodiment has raw materials including glass fiber grafted with the flame retardant phosphomolybdic nickel heteropolyacid, boron nitride modified with the flame retardant DDP, polyamide resin, antioxidant, compatibilizer, and lubricant. The added mass ratio is as follows: polyamide resin 56.5%, glass fiber grafted with the flame retardant phosphomolybdic nickel heteropolyacid 30%, boron nitride modified with the flame retardant DDP 10%, antioxidant 0.5%, compatibilizer 2%, and lubricant 1%.

[0150] In the preparation of the above high-efficiency flame-retardant and heat-conductive polyamide composite material, the raw material polyamide is heat-resistant polyamide PA6; the antioxidant is antioxidant 1010; the compatibilizer is AX8900; the lubricant is liquid paraffin.

[0151] The particle size of the boron nitride is about 1-2 μm, and after surface treatment with silane coupling agent KH560, it is bonded with the organic flame retardant DDP; the glass fiber is grafted with the inorganic flame retardant phosphomolybdic nickel heteropolyacid after being treated with silane coupling agent KH550.

[0152] The preparation method of the high-efficiency flame-retardant and heat-conducting polyamide composite material includes the following steps:

[0153] (1) Mix the polyamide resin dried at 70 °C for 5 h with the boron nitride modified with the flame retardant DDP, antioxidant, compatibilizer and lubricant evenly.

[0154] (2) Add the above-mentioned evenly mixed materials and the glass fiber grafted with phosphomolybdic nickel heteropolyacid to the feeding port of the internal mixer according to the above ratio, and carry out melt blending at 260 °C for 10 min, with a rotation speed of 80 rpm.

[0155] (3) Thermally press and form the melt obtained in step (2) to obtain a polyamide-glass fiber-boron nitride flame-retardant and heat-conducting composite material; the temperature of thermal press forming is 270 °C and the time is 10 min.

[0156] Example 7

[0157] The high-efficiency flame-retardant and heat-conducting polyamide composite material provided in this example has raw materials including glass fiber grafted with phosphomolybdic nickel heteropolyacid flame retardant, boron nitride modified with flame retardant DDP, polyamide resin, antioxidant, compatibilizer and lubricant, and their added mass ratios are: polyamide resin 46%, glass fiber grafted with phosphomolybdic nickel heteropolyacid flame retardant 30%, boron nitride modified with flame retardant DDP 20%, antioxidant 1%, compatibilizer 2% and lubricant 1%.

[0158] In the preparation of the above high-efficiency flame-retardant and heat-conducting polyamide composite material, the raw material polyamide is a mixture of heat-resistant polyamide PA56 and PA6; the antioxidant is antioxidant 1010; the compatibilizer is AX8900; the lubricant is molybdenum disulfide.

[0159] The particle size of the boron nitride is about 1-2 μm, and after surface treatment with silane coupling agent KH560, it is bonded with the organic flame retardant DDP; the glass fiber is grafted with the inorganic flame retardant phosphomolybdic nickel heteropolyacid after being treated with silane coupling agent KH550.

[0160] The preparation method of the high-efficiency flame-retardant and heat-conducting polyamide composite material includes the following steps:

[0161] (1) Mix the polyamide resin dried at 80 °C for 4 h with the boron nitride modified with the flame retardant DDP, antioxidant, compatibilizer and lubricant evenly.

[0162] (2) Add the above-mentioned uniformly mixed materials and the glass fiber grafted with phosphomolybdic nickel heteropolyacid into the feeding port of the internal mixer according to the above ratio, and melt and blend at 280 °C for 8 min, with a rotation speed of 70 rpm.

[0163] (3) Hot press the melt obtained in step (2) to obtain a polyamide-glass fiber-boron nitride flame-retardant and heat-conducting composite material; the temperature for hot pressing is 285 °C and the time is 10 min.

[0164] Example 8

[0165] The polyamide composite material with high-efficiency flame retardancy and heat conduction provided in this example has raw materials including glass fiber grafted with flame retardant phosphotungstic heteropolyacid, boron nitride modified with flame retardant DDP, polyamide resin, antioxidant, compatibilizer and lubricant, and their added mass ratios are: polyamide resin 61.5%, glass fiber grafted with flame retardant phosphotungstic heteropolyacid 5%, boron nitride modified with flame retardant DDP 30%, antioxidant 1%, compatibilizer 1.5% and lubricant 1%.

[0166] In the preparation of the above polyamide composite material with high-efficiency flame retardancy and heat conduction, the raw material polyamide is heat-resistant polyamide PA56; the antioxidant is antioxidant DSTP; the compatibilizer is AX8900; the lubricant is liquid paraffin.

[0167] The particle size of the boron nitride is about 1-2 μm, and it is surface-treated with silane coupling agent KH560 and then bonded with organic flame retardant DDP; the glass fiber is treated with silane coupling agent KH550 and then grafted with inorganic flame retardant phosphotungstic heteropolyacid.

[0168] The preparation method of the above polyamide composite material with high-efficiency flame retardancy and heat conduction includes the following steps:

[0169] (1) Mix the polyamide resin dried at 80 °C for 5 h with boron nitride modified with flame retardant DDP, antioxidant, compatibilizer and lubricant uniformly.

[0170] (2) Add the above-mentioned uniformly mixed materials and the glass fiber grafted with phosphotungstic heteropolyacid into the feeding port of the internal mixer according to the above ratio, and melt and blend at 270 °C for 8 min, with a rotation speed of 70 rpm.

[0171] (3) Hot press the melt obtained in step (2) to obtain a polyamide-glass fiber-boron nitride flame-retardant and heat-conducting composite material; the temperature for hot pressing is 280 °C and the time is 8 min.

[0172] Example 9

[0173] The high - efficiency flame - retardant and heat - conductive polyamide composite material provided by this embodiment has raw materials for preparation including glass fibers grafted with the flame retardant phosphomolybdic heteropolyacid, boron nitride modified with the flame retardant DDP, polyamide resin, antioxidant, compatibilizer and lubricant. The added mass ratios are as follows: polyamide resin 67%, glass fibers grafted with the flame retardant phosphomolybdic heteropolyacid 15%, boron nitride modified with the flame retardant DDP 15%, antioxidant 0.5%, compatibilizer 1.5% and lubricant 1%.

[0174] In the preparation of the above - mentioned high - efficiency flame - retardant and heat - conductive polyamide composite material, the raw material polyamide is heat - resistant polyamide PA6; the antioxidant is antioxidant 1010; the compatibilizer is AX8900; the lubricant is liquid paraffin.

[0175] The particle size of the boron nitride is about 1 - 2μm. After surface treatment with the silane coupling agent KH560, it is bonded with the organic flame retardant DDP; the glass fibers are grafted with the inorganic flame retardant phosphomolybdic heteropolyacid after being treated with the silane coupling agent KH550.

[0176] The preparation method of the above - mentioned high - efficiency flame - retardant and heat - conductive polyamide composite material includes the following steps:

[0177] (1) Mix the polyamide resin dried at 80°C for 6 h with boron nitride modified with the flame retardant DDP, antioxidant, compatibilizer and lubricant evenly.

[0178] (2) Add the above - mentioned evenly - mixed materials and glass fibers grafted with phosphomolybdic heteropolyacid to the feeding port of the internal mixer according to the above ratio, and carry out melt blending at 260°C for 10 min with a rotation speed of 80 rpm.

[0179] (3) Hot - press the melt obtained in step (2) to obtain a polyamide - glass fiber - boron nitride flame - retardant and heat - conductive composite material; the temperature for hot - pressing is 270°C and the time is 10 min.

[0180] Example 10

[0181] The high - efficiency flame - retardant and heat - conductive polyamide composite material provided by this embodiment has raw materials for preparation including glass fibers grafted with the flame retardant silicotungstic heteropolyacid, boron nitride modified with the flame retardant DOPOMA, polyamide resin, antioxidant, compatibilizer and lubricant. The added mass ratios are as follows: polyamide resin 61.5%, glass fibers grafted with the flame retardant silicotungstic heteropolyacid 30%, boron nitride modified with the flame retardant DOPOMA 5%, antioxidant 1%, compatibilizer 1.5% and lubricant 1%.

[0182] In the preparation of the above - mentioned high - efficiency flame - retardant and heat - conductive polyamide composite material, the raw material polyamide is heat - resistant polyamide PA6; the antioxidant is antioxidant DSTP; the compatibilizer is AX8900; the lubricant is molybdenum disulfide.

[0183] The particle size of the boron nitride is about 1-2 μm, and after surface treatment with silane coupling agent KH560, it is bonded with organic flame retardant DOPOMA; the glass fiber is grafted with inorganic flame retardant silicotungstic heteropolyacid after being treated with silane coupling agent KH550.

[0184] The preparation method of the high-efficiency flame-retardant and heat-conducting polyamide composite material comprises the following steps:

[0185] (1) Mix the polyamide resin dried at 80 °C for 5 h with the boron nitride modified by flame retardant DOPOMA, antioxidant, compatibilizer and lubricant evenly.

[0186] (2) Add the above evenly mixed materials and the glass fiber grafted with silicotungstic heteropolyacid to the feeding port of the internal mixer according to the above ratio, and carry out melt blending at 260 °C for 10 min, with a rotation speed of 80 rpm.

[0187] (3) Hot press the melt obtained in step (2) to prepare a polyamide-glass fiber-boron nitride flame-retardant and heat-conducting composite material; the temperature of hot pressing is 270 °C and the time is 10 min.

[0188] Comparative Example 1

[0189] The preparation process of this comparative example is basically the same as that of Example 1, and the difference lies in: replacing "the mass ratio of boron nitride modified by flame retardant DDP is 30%" with "the mass ratio is 3%".

[0190] Comparative Example 2

[0191] The preparation process of this comparative example is basically the same as that of Example 1, and the difference lies in: replacing "boron nitride modified by flame retardant DDP" with "unmodified boron nitride".

[0192] Comparative Example 3

[0193] The preparation process of this comparative example is basically the same as that of Example 1, and the difference lies in: replacing "glass fiber grafted with flame retardant phosphomolybdic nickel heteropolyacid" with "unmodified glass fiber".

[0194] Comparative Example 4

[0195] The preparation process of this comparative example is basically the same as that of Example 1, and the difference lies in: replacing "the mass ratio of glass fiber grafted with flame retardant phosphomolybdic nickel heteropolyacid is 20%" with "the mass ratio is 2%".

[0196] Comparative Example 5

[0197] The preparation process of this comparative example is basically the same as that of Example 1, and the difference lies in: the raw materials do not include "boron nitride modified by flame retardant DDP".

[0198] Comparative Example 6

[0199] The preparation process of this comparative example is basically the same as that of Example 1, except that the raw materials do not include "glass fiber grafted with the flame retardant phosphomolybdic nickel heteropolyacid".

[0200] The flame retardant and thermal conductivity of the flame retardant and thermal conductive composites prepared in Examples 1-10 and Comparative Examples 1-6 were tested using the GB / T 2408-2008 standard for flame retardancy, and the limiting oxygen index of the composites was tested using the ASTM D 2863-97 standard; the thermal conductivity of the composites was tested using the ASTM C 1113-90 standard. The flame retardancy and thermal conductivity of the related flame retardant and thermal conductive polyamide composites are shown in Table 1 below.

[0201] The glass fiber grafted with phosphomolybdic nickel heteropolyacid used in the above examples of the present invention was tested by FT-IR, and the results are as Figure 1 shown. It can be seen that there are 4 obvious characteristic peaks of heteropolyacid salts with Keggin structure at the wave number of 700-1100 cm -1 : 782 cm -1 is the antisymmetric stretching vibration frequency (Mo-Oc-Mo) of the common-edge bridging oxygen in the MoO6 octahedron; 898 cm -1 corresponds to the antisymmetric stretching vibration frequency of the bridging oxygen formed by the common-angle of 3 MoO6 octahedra and the metal coordination atom to form the Mo-Ob-Mo bond; 952 cm -1 corresponds to the anti-stretching vibration peak of the coordination atom and the terminal oxygen bond Mo=Od; 1056 cm -1 corresponds to the P-Oa vibration peak; there is no absorption peak in the range of 1100-1200 cm -1 ; the spectrum shows that PMo 11 Ni is well grafted on the surface of the glass fiber.

[0202] Table 1 Flame retardancy and thermal conductivity of flame retardant and thermal conductive polyamide composites

[0203]

[0204]

[0205] It can be seen from Table 1 that the limiting oxygen index of the polyamide-glass fiber-boron nitride flame retardant and thermal conductive composite provided by the present invention can reach 42.8%, the flame retardant grade can reach the V-0 grade of UL-94, and at the same time, the thermal conductivity of the composite at room temperature can reach 2.32 (W / m·K -1)。It can be seen from the comparative examples in Table 1 that when the mass ratios of the modified boron nitride filler and the modified glass fiber are reduced; or when the boron nitride and glass fiber are not modified, the flame retardancy and thermal conductivity of the composite material will decrease to varying degrees. These test results all prove that the composite material design scheme is reasonable and correct, and the strategy of bonding the flame retardant to the surface of the thermal conductive particles through chemical reactions is correct. It shows that the composite material is a material with high flame retardancy and high thermal conductivity, having excellent flame retardancy and thermal conductivity, and can be used for structural parts in battery housing packages, especially the housing and battery pack packaging materials of lithium-ion batteries for new energy vehicles. And the preparation method of this polyamide-glass fiber-boron nitride flame retardant and thermally conductive composite material is simple and convenient for large-scale production.

[0206] In addition, the inventor of this case also referred to the foregoing embodiments and conducted tests with other raw materials, process operations, and process conditions described in this specification, and all obtained relatively ideal results.

[0207] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. An efficient flame-retardant and heat-conductive polyamide composite material, characterized in that, The polyamide composite material is prepared from the following raw materials calculated by weight percentage: 46-67% of polyamide resin, 5-30% of glass fiber grafted with heteropolyacid, 5-30% of boron nitride modified with DDP or its derivatives and / or DOPO derivative DOPOMA, 0.5-1% of antioxidant, 1-2% of compatibilizer, and 0.5-1% of lubricant. The glass fiber grafted with heteropolyacid is obtained by chemically grafting heteropolyacid onto the surface of glass fiber. Among them, the heteropolyacid is a Keggin-type heteropolyacid, selected from any one or a combination of two or more of nickel phosphomolybdate heteropolyacid, phosphotungstic acid, phosphomolybdic acid, and silicotungstic acid.

2. The high-efficiency flame-retardant and heat-conductive polyamide composite material according to claim 1, wherein: The glass fiber includes any one or a combination of two of alkali-free continuous glass fiber and chopped glass fiber, and the diameter of the glass fiber is 6-13 μm.

3. The high-efficiency flame-retardant and heat-conductive polyamide composite material according to claim 1, wherein: The boron nitride modified with DDP or its derivatives and / or DOPO derivative DOPOMA is obtained by bonding and modifying DDP or its derivatives and / or DOPO derivative DOPOMA onto the surface of boron nitride.

4. The high-efficiency flame-retardant and heat-conducting polyamide composite material according to claim 3, characterized in that: The particle size of the boron nitride is 1-2 μm.

5. The high-efficiency flame-retardant and heat-conducting polyamide composite material according to claim 1, wherein: The polyamide resin includes any one or a combination of two of polyamide PA56 and PA6.

6. The high-efficiency flame-retardant and heat-conductive polyamide composite material according to claim 1, wherein: The antioxidant includes any one or a combination of two of phenolic antioxidants and thioester antioxidants.

7. The high-efficiency flame-retardant and heat-conductive polyamide composite material according to claim 1, wherein: The compatibilizer includes AX8900.

8. The high-efficiency flame-retardant and heat-conducting polyamide composite material according to claim 1, characterized in that: The lubricant includes any one or a combination of two or more of molybdenum disulfide, liquid paraffin, and polytetrafluoroethylene micropowder.

9. The high-efficiency flame-retardant and heat-conductive polyamide composite material according to claim 1, wherein: The limiting oxygen index of the high-efficiency flame-retardant and heat-conducting polyamide composite material is 32.4-42.8%, the flame-retardant grade is V-0 grade, and the thermal conductivity at room temperature is 0.95-2.32 W / (m•K -1 ) 10. The preparation method of the high-efficiency flame-retardant and heat-conducting polyamide composite material according to any one of claims 1-9, characterized in that, Including: Mix the polyamide resin, boron nitride modified with DDP or its derivatives and / or DOPO derivative DOPOMA, antioxidant, compatibilizer, and lubricant evenly, and then add the glass fiber grafted with heteropolyacid to a kneading device for melt blending, and then hot press molding to obtain the highly flame-retardant and heat-conductive polyamide composite material.

11. The preparation method according to claim 10, wherein Including: First, modify the glass fiber with a silane coupling agent, and then graft the heteropolyacid onto the surface of the glass fiber through an amino ring-opening reaction to obtain the glass fiber grafted with heteropolyacid. The heteropolyacid includes Keggin-type heteropolyacid, selected from any one or a combination of two or more of nickel phosphomolybdate heteropolyacid, phosphotungstic acid, phosphomolybdic acid, and silicotungstic acid.

12. The preparation method according to claim 11, wherein Specifically including: Hydrolyze the silane coupling agent in an acetic acid solution with a pH value of 4.0-5.0 for 1-2 h to obtain a hydrolysis solution, and immerse the pretreated glass fiber in the hydrolysis solution for 30-60 min to obtain modified glass fiber; Immerse the modified glass fiber in a heteropolyacid solution at room temperature for 8-9 h for an amino ring-opening reaction to graft the heteropolyacid onto the surface of the glass fiber to obtain the glass fiber grafted with heteropolyacid.

13. The preparation method according to claim 12, wherein, Also including: Calcine the glass fiber at 300-350 °C for 2-3 h first, and then calcine it at 400-450 °C for 1-2 h to obtain pretreated glass fiber.

14. The preparation method according to claim 10, characterized in that, Including: First, perform surface modification and grafting treatment on boron nitride with a silane coupling agent, and then bond DDP or its derivatives and / or DOPO derivative DOPOMA onto the surface of boron nitride through a carboxyl ring-opening reaction to obtain boron nitride modified with DDP or its derivatives and / or DOPO derivative DOPOMA.

15. The preparation method according to claim 14, characterized in that, Specifically include: Mix and stir a solution containing a silane coupling agent with boron nitride for 5 - 6 h to obtain boron nitride grafted with a silane coupling agent on the surface; Immerse the boron nitride grafted with a silane coupling agent on the surface in an organic solution containing DDP or its derivative and / or DOPO derivative DOPOMA for 22 - 24 h, and heat to 80 - 100 °C for 22 - 24 h to carry out a carboxyl ring-opening reaction, so that DDP or its derivative and / or DOPO derivative DOPOMA are bonded to the surface of boron nitride, and the boron nitride modified with DDP or its derivative and / or DOPO derivative DOPOMA is prepared.

16. The preparation method according to claim 11 or 14, characterized in that: The silane coupling agent includes any one or a combination of two of KH550 and KH560.

17. The preparation method according to claim 10, wherein Also include: First, dry the polyamide resin at 70 °C - 80 °C for 4 - 6 h, and then mix it evenly with boron nitride modified with DDP or its derivative and / or DOPO derivative DOPOMA, antioxidant, compatibilizer, and lubricant.

18. The preparation method according to claim 10, characterized in that: The temperature of the melt blending is 260 - 280 °C, and the rotation speed used is 50 - 80 rpm.

19. The preparation method according to claim 10, characterized in that: The temperature of the hot pressing and molding is 270 - 285 °C, and the time is 8 - 10 min.

20. Application of the high-efficiency flame-retardant and heat-conducting polyamide composite material according to any one of claims 1 - 9 in the preparation of the outer packaging of electronic and electrical appliances or the base of new energy vehicle batteries.

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