CN114015229A

CN114015229A - Nylon flame-retardant heat-conducting composite material and preparation method thereof

Info

Publication number: CN114015229A
Application number: CN202111558654.2A
Authority: CN
Inventors: 施雪军; 马爽; 杜祥祥; 韩永军; 李松田; 任爽
Original assignee: Pingdingshan University
Current assignee: Pingdingshan University
Priority date: 2021-12-20
Filing date: 2021-12-20
Publication date: 2022-02-08
Anticipated expiration: 2041-12-20
Also published as: CN114015229B

Abstract

The invention relates to a nylon flame-retardant heat-conducting composite material and a preparation method thereof. A nylon flame-retardant heat-conducting composite material comprises the following components: 49-97.5% of nylon resin; 1-20% of boron nitride modified by melamine salt flame retardant; 1-30% of aluminum oxide modified by melamine salt flame retardant; 0.5-1% of antioxidant. The preparation method of the nylon flame-retardant heat-conducting composite material comprises the steps of carrying out surface modification grafting treatment on aluminum oxide pellets by adopting a silane coupling agent, and then bonding a melamine salt flame retardant to the surfaces of the aluminum oxide pellets through an amino ring-opening reaction; blending and ball-milling hexagonal boron nitride and melamine salt flame retardant, and modifying the surface of the melamine salt flame retardant; uniformly dispersing the prepared aluminum oxide pellets of the surface modified melamine salt flame retardant, hexagonal boron nitride, nylon resin slices and the antioxidant to obtain a mixed base material, adding the mixed base material into a double-screw extruder for melting, blending and granulating to obtain composite material granules, and then performing injection molding or hot press molding.

Description

Nylon flame-retardant heat-conducting composite material and preparation method thereof

Technical Field

The invention relates to a nylon resin-based composite material, in particular to a nylon-boron nitride-aluminum oxide ternary flame-retardant heat-conducting composite material and a preparation method thereof.

Background

The nylon has excellent mechanical properties, oil resistance, corrosion resistance, wear resistance and the like, and is widely applied to engineering plastics. With the rapid development of industries such as communication, electronics, electrical and the like, the nylon material has higher requirements on the performance of nylon materials, for example, nylon used for packaging parts such as shells of household appliances, shells of table lamps, bases, sockets and shells of lithium ion batteries needs to have a certain heat conductivity coefficient, heat generated by the appliances can be dissipated out in time, and in the case of exposure to electrified working conditions such as high temperature, voltage, humidity and the like during actual use of nylon, the situations of electricity leakage, short circuit, electric sparks and the like are very easy to cause fire and have great potential safety hazards, so that the high flame retardant property is also a problem that needs to be solved urgently.

Generally, the addition of the flame retardant and the heat conducting particles is an effective way for effectively improving the heat conducting and flame retardant properties of the nylon composite material. However, the directly added flame retardant is easy to leak and exude during the long-term use of the composite material, thereby causing the problems of the flame retardant performance reduction of the composite material and the flame retardant pollution of the material use environment; meanwhile, the added heat-conducting particles cause the heat-conducting property of the nylon resin to be reduced due to the interface thermal resistance between the heat-conducting particles and the nylon matrix, and are not suitable for being used as high-performance heat-conducting materials. Under the background, the research on the nylon resin-based composite material with high strength, high flame retardance and high thermal conductivity has great scientific and economic significance.

The yield of PA6 and PA66 in nylon products is larger, and accounts for more than 90 percent of the total yield of nylon, so that the research on nylon 6 and nylon 66 and blends or alloy materials thereof in the field is relatively more. The Chinese patent application CN 105820557A discloses a flame-retardant heat-conducting nylon and a preparation method thereof, wherein the flame-retardant heat-conducting nylon comprises the following components in percentage by mass: 25-30% of nylon resin, 10-15% of antistatic resin, 25-35% of heat conducting filler, 12-15% of anion powder, 10-20% of flame retardant, 0.1-2% of coupling agent, 0.1-5% of lubricant and 0.1-2% of antioxidant. The modified flame-retardant heat-conducting nylon can be prepared by granulating the components through a double-screw extruder, and the prepared heat-conducting nylon has good toughness, flame retardance and high heat conduction and heat dissipation performance. The invention is mainly characterized in that various components are compounded in proportion, the flame retardant is directly added into the composite material, and the conditions of migration and exudation of the flame retardant are easily caused during the use of the composite material, so that the conditions of pollution of the use environment of the material by the flame retardant and reduction of the flame retardant property of the material are caused. The invention aims to solve the defect, and also takes nylon 6 and nylon 66 as main research substrates, and adopts the flame retardant to bond to the surface of the heat conducting particle through chemical reaction, thereby not only solving the dispersion problem of the flame retardant in the substrate, but also solving the situations of migration and exudation of the flame retardant in the substrate.

The Chinese patent application CN 105295360A discloses a high-thermal-conductivity flame-retardant nylon composite material and a preparation method thereof, wherein the flame-retardant high-thermal-conductivity nylon composite material comprises the following components in parts by weight: 30-60 parts of nylon, 65-10 parts of nylon, 10-30 parts of carbon micro-nano heat-conducting filler, 10-30 parts of metal micro-nano heat-conducting filler, 10-30 parts of non-metal non-carbon micro-nano heat-conducting filler, 5-15 parts of flame retardant, 0.5-2 parts of compatilizer, 0.5-1 part of antioxidant, 0.5-1 part of lubricant and 0-3 parts of toner. The high-thermal-conductivity flame-retardant nylon composite material has the advantages of good dispersibility, high thermal conductivity, small filling amount, small density and good processability. In the patent, metal micro powder and a carbon material are used as heat-conducting fillers, and a flame retardant is directly added into a matrix, so that the conditions of migration and exudation of the flame retardant are easily caused without treatment, and the conditions of pollution of the use environment of the material by the flame retardant and reduction of the flame retardant property of the material are caused. The invention discloses a method for preparing a heat-conducting particle by using boron nitride and aluminum oxide as heat-conducting fillers and bonding a flame retardant to the surface of the heat-conducting particle through a chemical reaction, so that the problems of migration and leakage of the flame retardant in a matrix are solved.

Chinese patent application CN 104744935 a discloses a long carbon chain heat-conducting nylon composite material and a preparation method thereof, and particularly relates to a long carbon chain heat-conducting nylon composite material, which mainly comprises: 20-40% of long carbon chain nylon resin, 30-50% of heat-conducting filler, 5-20% of reinforcing filler, 5-20% of halogen-free flame retardant, 0.1-0.5% of coupling agent, 0.4-1.0% of lubricant, 0.1-0.5% of antioxidant and 0.1-5% of toner, weighing the raw materials according to the mass percentage of the raw material formula, mixing the long carbon chain nylon resin and the coupling agent in a mixing cylinder, then adding the antioxidant for mixing, then adding the heat-conducting filler, the halogen-free flame retardant, the lubricant and the toner for mixing, and finally melting and extruding. Therefore, in the prior art, the flame retardant is mostly directly added into the nylon resin in the form of solid powder, the problem of interfacial compatibility exists between the flame retardant and the nylon resin, the flame retardant particles exist in the form of stress concentration point defects, and the strength and the flame retardant property of the nylon resin flame-retardant composite material are greatly reduced. In practical applications, the packaging material for the housing of the lithium battery has dual technical requirements for heat conduction and flame retardance.

In summary, it is more urgent to develop a material with flame retardant property, thermal conductivity, high performance and high cost performance in the application field of nylon composite materials.

Disclosure of Invention

The invention provides a nylon flame-retardant heat-conducting composite material and a preparation method thereof, aiming at the defects of the prior art, the nylon-boron nitride-aluminum oxide ternary flame-retardant heat-conducting composite material is prepared by adding aluminum oxide and boron nitride fillers of modified melamine salt flame retardants into nylon resin, extruding and granulating the mixture by a double-screw extruder and finally carrying out injection molding or hot press molding.

The invention aims to solve the problems of uneven dispersion of the flame retardant in the matrix and migration and leakage of the flame retardant in the matrix, bonds the melamine salt of the flame retardant to the surface of the heat-conducting inorganic particle through chemical reaction, solves the problems of dissociation and uneven dispersion of the flame retardant in the matrix, and simultaneously solves the double problems of low heat conductivity coefficient of the nylon composite material by the heat-conducting inorganic particle.

The technical scheme adopted by the invention is as follows:

the flame-retardant heat-conducting nylon composite material is prepared from the following raw material components in percentage by mass: 49-97.5% of nylon resin; 1-20% of boron nitride modified by melamine salt flame retardant; 1-30% of aluminum oxide modified by melamine salt flame retardant; 0.5-1% of antioxidant.

The nylon flame-retardant heat-conducting composite material comprises the following raw material components in percentage by mass: 49-75% of nylon resin; 10-20% of boron nitride modified by melamine salt flame retardant; 10-20% of aluminum oxide modified by melamine salt flame retardant; 0.5-1% of antioxidant.

The nylon flame-retardant heat-conducting composite material comprises the following raw material components in percentage by mass: 80-97.5% of nylon resin; 1-10% of boron nitride modified by melamine salt flame retardant; 1-18% of aluminum oxide modified by melamine salt flame retardant; 0.5-1% of antioxidant.

The nylon flame-retardant heat-conducting composite material comprises the following raw material components in percentage by mass: 70-80% of nylon resin; 8-15% of boron nitride modified by melamine salt flame retardant; 11.5-20% of aluminum oxide modified by melamine salt flame retardant; 0.5-1% of antioxidant.

The addition amount of boron nitride of the surface modification flame retardant of the nylon flame-retardant heat-conducting composite material is 1-20 wt% of the mass fraction of the composite system; the addition amount of the aluminum oxide of the surface modification flame retardant is 1-30 wt% of the mass fraction of the composite system.

The addition amount of boron nitride of the surface modification flame retardant of the nylon flame-retardant heat-conducting composite material is 10-20 wt% of the mass fraction of the composite system; the addition amount of the aluminum oxide of the surface modification flame retardant is 20-30 wt% of the mass fraction of the composite system.

The addition amount of boron nitride of the surface modification flame retardant of the nylon flame-retardant heat-conducting composite material is 1-10 wt% of the mass fraction of the composite system; the addition amount of the aluminum oxide of the surface modification flame retardant is 1-10 wt% of the mass fraction of the composite system.

The addition amount of boron nitride of the surface modification flame retardant of the nylon flame-retardant heat-conducting composite material is 8-15 wt% of the mass fraction of the composite system; the addition amount of the aluminum oxide of the surface modification flame retardant is 10-20 wt% of the mass fraction of the composite system.

The preparation method of the nylon flame-retardant heat-conducting composite material adopts the aluminum oxide pellets, the surfaces of the aluminum oxide pellets are modified by the silane coupling agent KH-560 and are bonded with the melamine salt flame retardant, wherein the addition amount of the aluminum oxide pellets of the melamine salt flame retardant with the surface modification is 1-30% of that of the composite material; blending and ball-milling hexagonal boron nitride and a melamine salt flame retardant by a ball mill to obtain boron nitride with the surface modified with the melamine salt flame retardant, wherein the addition amount of the modified boron nitride is 1-20% of that of the composite material; then uniformly dispersing the aluminum oxide pellets of the surface modified melamine salt flame retardant, the boron nitride of the surface modified melamine salt flame retardant, the nylon resin slices and the antioxidant to obtain a mixed base material; and performing melt blending, granulation and injection molding by using a double-screw extruder to finally prepare the nylon-boron nitride-aluminum oxide ternary flame-retardant heat-conducting composite material.

The particle size of hexagonal boron nitride adopted by the nylon flame-retardant heat-conducting composite material is about 1-30 mu m, and the hexagonal boron nitride and melamine salt are subjected to blending and ball milling to graft a melamine salt flame retardant on the surface of the composite material; the diameter of the small aluminum oxide balls is about 1-30 mu m, and the small aluminum oxide balls modified by the melamine salt flame retardant are obtained by bonding the melamine salt flame retardant after the surface of the small aluminum oxide balls is grafted with the silane coupling agent KH-560; the melamine salt flame retardant is at least one of melamine urate, melamine phosphate and melamine sulfate. The nylon resin is nylon 6 or nylon 66 or alloy resin of two kinds of nylon; the antioxidant comprises one or more of an antioxidant 1010, an antioxidant 1076 and an antioxidant 1098.

A preparation method of a nylon flame-retardant heat-conducting composite material comprises the following steps:

1) performing surface modification grafting treatment on the aluminum oxide pellets by adopting a silane coupling agent KH-560, and then bonding a melamine salt flame retardant to the surfaces of the aluminum oxide pellets through an amino ring-opening reaction to obtain the aluminum oxide pellets of which the surfaces are modified with the melamine salt flame retardant;

2) blending and ball-milling hexagonal boron nitride and melamine salt flame retardant to obtain boron nitride with the surface modified with the melamine salt flame retardant;

3) uniformly dispersing the alumina pellets of the surface modified melamine salt flame retardant prepared in the step 1) and the step 2), the boron nitride of the surface modified melamine salt flame retardant, the nylon resin slices and the antioxidant to obtain a mixed base material;

4) adding the mixed base material obtained in the step 3) into a double-screw extruder, and carrying out melt blending and grain cutting through the extruder to obtain granules of the composite material;

5) and (3) carrying out injection molding or hot press molding on the granules obtained in the step 4) to obtain the nylon-boron nitride-aluminum oxide flame-retardant heat-conducting composite material.

The preparation method of the nylon flame-retardant heat-conducting composite material comprises the following specific steps of in step 1), preparing the aluminum oxide pellets of which the surfaces are modified with the melamine salt flame retardant:

1.1) modifying the surface of an alumina pellet with a silane coupling agent KH-560;

in the step 1.1), sequentially adding alumina into an ethanol solution containing KH-560, reacting in a water bath for 6-12 hours, carrying out suction filtration to obtain KH-560 modified alumina pellets, repeatedly washing with distilled water and ethanol for 5 times, and carrying out freeze drying to obtain the alumina pellets with the surface modified with KH-560;

1.2) bonding flame retardant melamine salts to the surface of alumina through a ring-opening reaction;

in the step 1.2), adding aluminum oxide with the surface modified with KH-560 into an organic solvent containing melamine salt flame retardant, soaking for 24 hours, magnetically stirring, heating in water bath, reacting for 24-36 hours, filtering the mixed solution, washing the filter residue with ethanol for 3-5 times, and freeze-drying to obtain the aluminum oxide spheres with the surface bonded with the melamine salt flame retardant.

In the preparation method of the nylon flame-retardant heat-conducting composite material, in the step 2), the specific steps for preparing the surface-modified melamine salt flame retardant boron nitride are as follows: weighing hexagonal boron nitride and melamine polyphosphate according to a corresponding proportion, placing the hexagonal boron nitride and the melamine polyphosphate into a ball milling tank body, then adding a proper amount of absolute ethyl alcohol to fully wet the hexagonal boron nitride and the melamine polyphosphate, ball milling for 8 hours by using zirconia balls, standing for a period of time after the reaction is finished, then taking out ball milling materials, carrying out suction filtration, repeatedly and alternately washing for 3-5 times by using ethyl alcohol and distilled water, and carrying out freeze drying to obtain the melamine salt flame retardant modified boron nitride.

In the prior art, because the melamine salt flame retardant is mostly directly added into the nylon resin in the form of solid particles, the interface problem exists between the melamine salt flame retardant and the nylon resin, the flame retardant particles exist in the form of stress concentration point defects, and the strength and the flame retardant property of the nylon resin flame-retardant composite material are greatly reduced. Compared with the prior art, the invention has the following beneficial effects:

(1) according to the nylon flame-retardant heat-conducting composite material provided by the invention, due to the high heat-conducting property of the boron nitride and the aluminum oxide, and the boron nitride and the aluminum oxide are uniformly dispersed in the nylon resin matrix, the heat-conducting property of the nylon composite material can be greatly improved by a proper proportion of the boron nitride and the aluminum oxide.

(2) According to the nylon flame-retardant heat-conducting composite material provided by the invention, the surfaces of boron nitride and aluminum oxide are modified by the melamine salt flame retardant, namely, the melamine salt flame retardant is bonded, so that the flame retardant property of the nylon composite material can be effectively and greatly improved.

(3) The preparation method of the nylon flame-retardant heat-conducting composite material provided by the invention is simple, mild in reaction conditions and suitable for large-scale industrial production.

(4) The nylon flame-retardant heat-conducting composite material provided by the invention has excellent flame retardance, heat conduction and mechanical properties, can be applied to a structural flame-retardant heat-conducting material, and can be used as a shell packaging material of an electronic appliance; the novel heat-conducting flame-retardant material is particularly applied to a shell and a base of an LED lamp and a shell packaging piece of a new energy automobile battery, namely, a place with the requirements of good mechanical strength, excellent flame retardance and excellent heat conducting property.

According to the nylon flame-retardant heat-conducting composite material prepared by the preparation method, the melamine salt flame retardant is bonded on the surfaces of the aluminum oxide and the boron nitride, and the flame retardant is linked on the surfaces of the inorganic particles, so that the defects that in the prior art, the flame retardant and a nylon resin matrix are not uniformly blended, and the flame retardant is easy to leak and migrate in the composite material to pollute the use environment of the material are overcome; meanwhile, the compatibility between the boron nitride and alumina particles and the nylon matrix can be improved, so that the interface thermal resistance between the boron nitride and alumina particles and the nylon resin is reduced, and the heat-conducting property of the nylon resin flame-retardant composite material is improved. The reason why the boron nitride and alumina are chosen for the present system is: boron nitride is a two-dimensional sheet-shaped structure heat conduction material, and is easy to stack and disperse unevenly; the aluminum oxide is a zero-dimensional small ball, and the heat conductivity coefficient of the composite material at low filling amount can be improved by compounding the small ball and the sheet layer; in addition, the two inorganic fillers are absolutely non-combustible, can cover the surface of the composite material, block oxygen from contacting with combustible substances, block a combustion path and play a role in flame retardance of the fillers.

Drawings

FIG. 1 is a scanning electron micrograph of carbon residue after cone calorimeter testing of the composite prepared in example 1;

FIG. 2 is a graph of the thermal weight loss of the alumina of example 1 and its flame retardant modified alumina;

FIG. 3 is a graph of the thermal weight loss of boron nitride and its flame retardant modified boron nitride of example 1.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

Example 1

The nylon resistor of the embodimentA flame-retardant and heat-conductive composite material comprises aluminum oxide pellets (Al) modified by melamine polyphosphate (MPP) flame retardant₂O₃) And Boron Nitride (BN) filler, nylon 6 resin and antioxidant 1010, wherein the four are added in the mass ratio of:

69% of nylon 6 resin;

10% of MPP modified boron nitride;

20% of MPP modified alumina;

and (3) antioxidant 10101%.

The particle size of the boron nitride is about 3 mu m, and the boron nitride and MPP are blended and ball-milled to graft MPP on the surface of the boron nitride to obtain BN-MPP; the diameter of the small alumina balls is about 10 mu m, the surface of the small alumina balls is grafted with a silane coupling agent KH-560, and MPP is bonded to obtain Al₂O₃-KH560-MPP。

The preparation method of the nylon flame-retardant heat-conducting composite material comprises the following steps:

(1) performing surface modification grafting treatment on the aluminum oxide pellet by adopting a silane coupling agent KH-560, and bonding MPP to the surface of the aluminum oxide pellet through an amino ring-opening reaction to obtain Al with the surface modified with MPP₂O₃-KH560-MPP；

a. Modifying the surface of the alumina globule with a silane coupling agent KH-560: sequentially adding alumina into an ethanol solution containing KH-560, carrying out water bath reaction for 12 hours, carrying out suction filtration to obtain KH-560 modified alumina pellets, repeatedly washing with distilled water and ethanol for 5 times, and carrying out freeze drying to obtain the alumina pellets with the surface modified with KH-560;

b. bonding MPP to the alumina surface by a ring opening reaction: adding aluminum oxide with the surface modified with KH-560 into an organic solvent containing MPP, soaking for 24 hours, magnetically stirring, heating in water bath, reacting for 36 hours, filtering the mixed solution, washing the filter residue with ethanol for 3-5 times, and freeze-drying to obtain aluminum oxide pellets with the surface bonded with MPP, namely Al₂O₃-KH560-MPP；

(2) Preparing boron nitride with modified surface MPP: weighing hexagonal boron nitride and MPP according to a corresponding proportion, placing the hexagonal boron nitride and the MPP into a ball milling tank, adding a proper amount of absolute ethyl alcohol to fully wet the hexagonal boron nitride and the MPP, ball milling the hexagonal boron nitride and the MPP for 8 hours by using zirconia balls, standing the mixture for a period of time after the reaction is finished, taking out ball milling materials, carrying out suction filtration on the ball milling materials, repeatedly and alternately washing the ball milling materials for 3-5 times by using ethanol and distilled water, and carrying out freeze drying to obtain boron nitride modified by melamine salt flame retardant, namely BN-MPP;

(3) mixing Al prepared in the step (1) and the step (2)₂O₃Uniformly stirring KH560-MPP, BN-MPP, nylon 6 resin slices and an antioxidant 1010 to obtain a mixed base material;

(4) adding the mixed base material obtained in the step (3) into a double-screw extruder, carrying out melt blending through the extruder, and carrying out extrusion granulation to obtain granules of the composite material;

preferably, the processing temperature of the double-screw extruder is 220-280 ℃, and the rotating speed is set to be 70-100 r/min;

(5) and (4) performing injection molding on the granules obtained in the step (4) by using an injection molding machine to obtain the nylon-boron nitride-aluminum oxide ternary flame-retardant heat-conducting composite material.

A scanning electron microscope picture of carbon residue after the nylon-boron nitride-aluminum oxide ternary flame-retardant heat-conducting composite material obtained in the step (5) is tested by a cone calorimeter is shown in figure 1; the alumina globules and modified particles thereof involved in step (1) are shown in figure 2 by TGA test results; the results of TGA measurement of the boron nitride and the flame retardant-modified boron nitride involved in step (2) are shown in fig. 3.

The flame retardant and heat conductive nylon composite material obtained in example 1 was tested for flame retardant properties according to GB/T2406-2009 standard, for limiting oxygen index according to ASTM D2863-97 standard, and for heat conductive properties according to ASTM C1113-90 standard, the results are shown in Table 1.

Example 2

The nylon flame-retardant heat-conducting composite material comprises aluminum oxide pellets modified by melamine polyphosphate flame retardant, boron nitride filler, nylon 6 resin and antioxidant 1010, wherein the four components are added in the following mass ratio:

59% of nylon 6 resin;

10% of MPP modified boron nitride;

30% of MPP modified alumina;

and (3) antioxidant 10101%.

(3) mixing Al prepared in the step (1) and the step (2)₂O₃Uniformly stirring the-KH 560-MPP, the BN-MPP, the nylon 6 resin slices and the antioxidant 1010 to obtain a mixed base material；

(4) Adding the mixed base material obtained in the step (3) into a double-screw extruder, carrying out melt blending through the extruder, and carrying out extrusion granulation to obtain granules of the composite material; the processing temperature of the double-screw extruder is 220-280 ℃, and the rotating speed is set to be 70-100 r/min;

The flame retardant and heat conductive nylon composite material obtained in example 2 was tested for flame retardant properties according to GB/T2406-2009 standard, for limiting oxygen index according to ASTM D2863-97 standard, and for heat conductive properties according to ASTM C1113-90 standard, the results are shown in Table 1.

Example 3

49% of nylon 6 resin;

20% MPP modified boron nitride;

30% of MPP modified alumina;

and (3) antioxidant 10101%.

the processing temperature of the double-screw extruder is 220-280 ℃, and the rotating speed is set to be 70-100 r/min;

The flame retardant and heat conductive nylon composite material obtained in example 3 was tested for flame retardant properties using the GB/T2406-2009 standard, for limiting oxygen index using the ASTM D2863-97 standard, and for heat conductive properties using the ASTM C1113-90 standard, the results are shown in Table 1.

Example 4

The nylon flame-retardant heat-conducting composite material of the embodiment uses the aluminum oxide pellets modified by the melamine polyphosphate flame retardant, the boron nitride filler, the nylon 6 resin and the antioxidant 1010, and the four components are added in the following mass ratio:

59.5 percent of nylon 6 resin;

10% of MPP modified boron nitride;

30% of MPP modified alumina;

10100.5% of antioxidant.

The particle size of the boron nitride is about 3 mu m, and the boron nitride and MPP are blended and ball-milled to graft MPP on the surface of the boron nitride to obtain BN-MPP; the diameter of the alumina pellets is about 20 mu m, a silane coupling agent KH-560 is grafted on the surface of the alumina pellets, and MPP is bonded to obtain Al₂O₃-KH560-MPP。

(4) adding the mixed base material obtained in the step (3) into a double-screw extruder, carrying out melt blending through the extruder, and carrying out extrusion granulation to obtain granules of the composite material; the processing temperature of the double-screw extruder is 220-280 ℃, and the rotating speed is set to be 70-120 r/min;

Example 5

The nylon flame-retardant heat-conducting composite material of the embodiment adopts aluminum oxide pellets modified by melamine polyphosphate flame retardant, boron nitride filler, nylon 6 resin and antioxidant 1010, and the mass ratio of the added materials is as follows:

59% of nylon 6 resin;

20% MPP modified boron nitride;

20% of MPP modified alumina;

and (3) antioxidant 10101%.

The particle size of the boron nitride is about 5 mu m, and the boron nitride and MPP are blended and ball-milled to graft MPP on the surface of the boron nitride to obtain BN-MPP; the diameter of the alumina pellets is about 12 mu m, a silane coupling agent KH-560 is grafted on the surface of the alumina pellets, and MPP is bonded to obtain Al₂O₃-KH560-MPP。

a. Modifying the surface of the alumina globule with a silane coupling agent KH-560: sequentially adding alumina into an ethanol solution containing KH-560, carrying out water bath reaction for 8 hours, carrying out suction filtration to obtain KH-560 modified alumina pellets, repeatedly washing with distilled water and ethanol for 5 times, and carrying out freeze drying to obtain the alumina pellets with the surface modified with KH-560;

Example 6

The nylon flame-retardant heat-conducting composite material comprises aluminum oxide pellets modified by melamine polyphosphate flame retardant, boron nitride filler, nylon 66 resin and antioxidant 1010, wherein the four components are added in the following mass ratio:

49.5 percent of nylon 6 resin;

20% MPP modified boron nitride;

30% of MPP modified alumina;

10100.5% of antioxidant.

The particle size of the boron nitride is about 6 mu m, and the boron nitride and MPP are blended and ball-milled to graft MPP on the surface of the boron nitride to obtain BN-MPP; the diameter of the alumina pellets is about 20 mu m, a silane coupling agent KH-560 is grafted on the surface of the alumina pellets, and MPP is bonded to obtain Al₂O₃-KH560-MPP。

(3) the step (1) and the step (2)Al produced in (1)₂O₃Uniformly stirring KH560-MPP, BN-MPP, nylon 66 resin slices and an antioxidant 1010 to obtain a mixed base material;

Example 7

The nylon flame-retardant heat-conducting composite material comprises aluminum oxide pellets modified by melamine polyphosphate flame retardant, boron nitride filler, blend resin of nylon 6 and nylon 66 and antioxidant 1010, wherein the four components are added in the following mass ratio:

60% of nylon 6 and nylon 66 resin (in any proportion);

19% MPP modified boron nitride;

20% of MPP modified alumina;

and (3) antioxidant 10101%.

The particle size of the boron nitride is about 8 mu m, and the boron nitride and MPP are blended and ball-milled to graft MPP on the surface of the boron nitride to obtain BN-MPP; the diameter of the alumina pellets is about 15 mu m, a silane coupling agent KH-560 is grafted on the surface of the alumina pellets, and MPP is bonded to obtain Al₂O₃-KH560-MPP。

(3) mixing Al prepared in the step (1) and the step (2)₂O₃Uniformly stirring the blended pellets of-KH 560-MPP and BN-MPP, nylon 6 and nylon 66 resin with an antioxidant 1010 to obtain a mixed base material;

Example 8

The nylon flame-retardant heat-conducting composite material comprises aluminum oxide pellets modified by melamine polyphosphate flame retardant, boron nitride filler, nylon 66 resin and antioxidant 1010, wherein the adding mass ratio of the aluminum oxide pellets to the boron nitride filler is as follows:

59.5% of nylon 66 resin;

10% of MPP modified boron nitride;

30% of MPP modified alumina;

10100.5% of antioxidant.

The particle size of the boron nitride is about 10 mu m, and the boron nitride and MPP are blended and ball-milled to graft MPP on the surface of the boron nitride to obtain BN-MPP; the diameter of the alumina pellets is about 30 mu m, a silane coupling agent KH-560 is grafted on the surface of the alumina pellets, and MPP is bonded to obtain Al₂O₃-KH560-MPP。

a. Modifying the surface of the alumina globule with a silane coupling agent KH-560: sequentially adding alumina into ethanol solution containing KH-560, reacting in water bath for 6-12 hr, vacuum filtering to obtain KH-560 modified alumina spheres, repeatedly washing with distilled water and ethanol for 5 times, and freeze drying to obtain surface modified KH-560 alumina spheres

(3) mixing Al prepared in the step (1) and the step (2)₂O₃-KH560-MPP, BN-MPP, NiUniformly stirring the Long66 resin granules and the antioxidant 1010 to obtain a mixed base material;

(4) adding the mixed base material obtained in the step (3) into a double-screw extruder, carrying out melt blending through the extruder, and carrying out extrusion granulation to obtain granules of the composite material (the processing temperature of the double-screw extruder is 220-280 ℃, and the rotating speed is set to be 70-100 r/min);

Example 9

50% of nylon 6 resin;

20% MPP modified boron nitride;

30% of MPP modified alumina;

10761% of antioxidant.

The particle size of the boron nitride is about 1 mu m, and the boron nitride and MPP are blended and ball-milled to graft MPP on the surface of the boron nitride to obtain BN-MPP; the diameter of the small alumina balls is about 10 mu m, the surface of the small alumina balls is grafted with a silane coupling agent KH-560, and MPP is bonded to obtain Al₂O₃-KH560-MPP。

b. bonding MPP to oxygen by a ring opening reactionSurface of aluminum oxide: adding aluminum oxide with the surface modified with KH-560 into an organic solvent containing MPP, soaking for 24 hours, magnetically stirring, heating in water bath, reacting for 36 hours, filtering the mixed solution, washing the filter residue with ethanol for 3-5 times, and freeze-drying to obtain aluminum oxide pellets with the surface bonded with MPP, namely Al₂O₃-KH560-MPP；

(3) mixing Al prepared in the step (1) and the step (2)₂O₃Uniformly stirring KH560-MPP, BN-MPP, nylon 66 resin slices and an antioxidant 1076 to obtain a mixed base material;

(4) adding the mixed base material obtained in the step (3) into a double-screw extruder, carrying out melt blending through the extruder, and carrying out extrusion granulation to obtain granules of the composite material; preferably, the processing temperature of the double-screw extruder is 220-280 ℃, and the rotating speed is set to be 70-100 r/min;

Example 10

In the nylon flame-retardant heat-conducting composite material of the embodiment, the raw material is aluminum oxide pellets (Al) modified by melamine polyphosphate (MPP) flame retardant₂O₃) And Boron Nitride (BN) filler, nylon 6 resin and an antioxidant 1076, wherein the adding mass ratio of the four components is as follows:

69.5% of nylon 6 resin;

10% of MPP modified boron nitride;

20% of MPP modified alumina;

10760.5% of antioxidant.

The boron nitride particlesThe diameter of the mixture is about 10 mu m, and the mixture is blended with MPP and subjected to ball milling to graft MPP on the surface of the mixture so as to obtain BN-MPP; the diameter of the small alumina balls is about 10 mu m, the surface of the small alumina balls is grafted with a silane coupling agent KH-560, and MPP is bonded to obtain Al₂O₃-KH560-MPP。

(3) mixing Al prepared in the step (1) and the step (2)₂O₃Uniformly stirring KH560-MPP, BN-MPP, nylon 6 resin slices and an antioxidant 1076 to obtain a mixed base material;

(4) adding the mixed base material obtained in the step (3) into a double-screw extruder, carrying out melt blending through the extruder, and carrying out extrusion granulation to obtain granules of the composite material, wherein the processing temperature of the double-screw extruder is 220-280 ℃, and the rotating speed is set to be 70-100 r/min;

Example 11

The nylon flame-retardant heat-conducting composite material comprises aluminum oxide pellets modified by melamine polyphosphate flame retardant, boron nitride filler, nylon 6 resin and antioxidant 1098, wherein the aluminum oxide pellets, the boron nitride filler, the nylon 6 resin and the antioxidant 1098 are added in the following mass ratio:

59% of nylon 6 resin;

10% of MPP modified boron nitride;

30% of MPP modified alumina;

10981% of antioxidant.

a. Modifying the surface of the alumina globule with a silane coupling agent KH-560: sequentially adding alumina into an ethanol solution containing KH-560, carrying out water bath reaction for 6-12 hours, carrying out suction filtration to obtain KH-560 modified alumina pellets, repeatedly washing with distilled water and ethanol for 5 times, and carrying out freeze drying to obtain the alumina pellets with the surface modified with KH-560;

b. bonding MPP to the alumina surface by a ring opening reaction: adding aluminum oxide with surface modified KH-560 into organic solvent containing MPP, soaking for 24 hr, magnetically stirring, heating in water bath, reacting for 36 hr, and reactingFiltering the mixed solution, washing the filter residue with ethanol for 3-5 times, and freeze drying to obtain aluminum oxide pellet with surface bonded with MPP (modified Polypropylene) to obtain Al₂O₃-KH560-MPP；

(3) mixing Al prepared in the step (1) and the step (2)₂O₃Uniformly stirring KH560-MPP, BN-MPP, nylon 6 resin slices and an antioxidant 1098 to obtain a mixed base material;

Example 12

The nylon flame-retardant heat-conducting composite material comprises aluminum oxide pellets modified by melamine polyphosphate flame retardant, boron nitride filler, nylon 66 resin, antioxidant 1010 and antioxidant 1098, wherein the aluminum oxide pellets and the boron nitride filler are added in the following mass ratio:

49% of nylon 6 resin;

20% MPP modified boron nitride;

30% of MPP modified alumina;

1 percent of antioxidant 1010 and antioxidant 1098 (in any mass ratio).

The particle size of the boron nitride is about 2 mu m, and the boron nitride and MPP are blended and ball-milled to graft MPP on the surface of the boron nitride to obtain BN-MPP; the diameter of the alumina pellet is about 10 mu m, and the surface of the alumina pellet is graftedSilane coupling agent KH-560, bonding MPP to obtain Al₂O₃-KH560-MPP。

(3) mixing Al prepared in the step (1) and the step (2)₂O₃Uniformly stirring-KH 560-MPP, BN-MPP, nylon 66 resin slices, an antioxidant 1010 and an antioxidant 1098 (in any mass ratio) to obtain a mixed base material;

Example 13

The nylon flame-retardant heat-conducting composite material of the embodiment uses aluminum oxide pellets (Al) modified by melamine urate (MCA) flame retardant₂O₃) And Boron Nitride (BN) filler, nylon 6 resin and antioxidant 1010, wherein the four are added in the mass ratio of:

69% of nylon 6 resin;

10% MCA modified boron nitride;

MCA modified alumina 20%;

and (3) antioxidant 10101%.

The particle size of the boron nitride is about 8 mu m, and the boron nitride and MCA are subjected to blending and ball milling to enable the surface of the boron nitride to be grafted with MCA, so that BN-MCA is obtained; the diameter of the small alumina balls is about 10 mu m, a silane coupling agent KH-560 is grafted on the surfaces of the small alumina balls, and MCA is bonded to obtain Al₂O₃-KH560-MCA。

(1) performing surface modification grafting treatment on the alumina globule by adopting a silane coupling agent KH-560, and bonding MCA to the surface of the alumina globule through an amino ring-opening reaction to obtain the MCA surface modified Al₂O₃-KH560-MCA；

b. bonding MCA to the alumina surface by a ring opening reaction: adding aluminum oxide with surface modified KH-560 into MCA-containing organic solvent, soaking for 24 hr, magnetically stirring, heating in water bath, reacting for 24 hr, filtering, washing the residue with ethanol for 3-5 times, and freezingDrying to obtain alumina pellets with MCA bonded on the surface, namely obtaining Al₂O₃-KH560-MCA；

(2) Preparation of surface-modified MCA boron nitride: weighing hexagonal boron nitride and MCA according to a corresponding proportion, placing the hexagonal boron nitride and MCA into a ball milling tank, adding a proper amount of absolute ethyl alcohol to fully wet the hexagonal boron nitride and the MCA, ball milling the hexagonal boron nitride and the MCA for 8 hours by using zirconia balls, standing the mixture for a period of time after the reaction is finished, taking out ball milling materials, carrying out suction filtration on the ball milling materials, repeatedly and alternately washing the ball milling materials for 3-5 times by using ethanol and distilled water, and carrying out freeze drying to obtain boron nitride modified by melamine salt flame retardant, namely BN-MCA;

(3) mixing Al prepared in the step (1) and the step (2)₂O₃Uniformly stirring KH560-MCA, BN-MCA, nylon 6 resin slices and an antioxidant 1010 to obtain a mixed base material;

Example 14

The nylon flame-retardant heat-conducting composite material of the embodiment uses raw materials including aluminum oxide pellets modified by Melamine Sulfate (MS) flame retardant, boron nitride filler, nylon 6 resin and antioxidant 1010, and the four are added in the mass ratio:

59% of nylon 6 resin;

MS-modified boron nitride 10%;

30% of MS modified alumina;

and (3) antioxidant 10101%.

The particle size of the boron nitride is about 2 mu m, and the boron nitride and MS are subjected to blending and ball milling to graft MPP on the surface of the boron nitride to obtain BN-MS; the diameter of the small alumina balls is about 10 mu m, the surface of the small alumina balls is grafted with a silane coupling agent KH-560, and MPP is bonded to obtain Al₂O₃-KH560-MS。

(1) performing surface modification grafting treatment on the aluminum oxide spheres by adopting a silane coupling agent KH-560, and then bonding MS to the surfaces of the aluminum oxide spheres through an amino ring-opening reaction to obtain Al with surface modification of MS₂O₃-KH560-MS；

b. bonding MS to the alumina surface by ring opening reaction: adding aluminum oxide with the surface modified with KH-560 into an organic solvent containing MS, soaking for 24 hours, magnetically stirring, heating in water bath, reacting for 36 hours, filtering the mixed solution, washing the filter residue with ethanol for 3-5 times, and freeze-drying to obtain aluminum oxide pellets with surface bonded with MPP, namely Al₂O₃-KH560-MS；

(2) Preparing boron nitride with surface modified MS: weighing hexagonal boron nitride and MS according to a corresponding proportion, placing the hexagonal boron nitride and MS into a ball milling tank, adding a proper amount of absolute ethyl alcohol to fully wet the hexagonal boron nitride and the MS, ball milling the hexagonal boron nitride and the MS for 8 hours by using zirconia balls, standing the mixture for a period of time after the reaction is finished, taking out the ball milled material, performing suction filtration on the ball milled material, repeatedly and alternately washing the ball milled material for 3 to 5 times by using ethanol and distilled water, and performing freeze drying to obtain boron nitride modified by a melamine salt flame retardant, namely BN-MS;

(3) mixing Al prepared in the step (1) and the step (2)₂O₃Uniformly stirring KH560-MS, BN-MS, nylon 6 resin slices and an antioxidant 1010 to obtain a mixed base material;

Example 15

49% of nylon 66 resin;

20% MPP modified boron nitride;

30% of MPP modified alumina;

and (3) antioxidant 10101%.

The particle size of the boron nitride is about 2 mu m, and the boron nitride and MPP are blended and ball-milled to graft MPP on the surface of the boron nitride to obtain BN-MPP; the diameter of the small alumina balls is about 10 mu m, the surface of the small alumina balls is grafted with a silane coupling agent KH-560, and MPP is bonded to obtain Al₂O₃-KH560-MPP。

(3) mixing Al prepared in the step (1) and the step (2)₂O₃Uniformly stirring KH560-MPP, BN-MPP, nylon 66 resin slices and an antioxidant 1010 to obtain a mixed base material;

The flame-retardant heat-conducting composite materials prepared in the embodiments 1 to 15 are tested for flame-retardant performance by adopting GB/T2408-2008 standard, the flame-retardant grade results are all above V-2 grade, and when the sum of the addition amount of the modified boron nitride and the alumina pellets exceeds 15%, the flame retardance of the composite materials reaches V-1 grade; testing the limiting oxygen index of the composite material by adopting an ASTM D2863-97 standard; the thermal conductivity of the composite was tested using ASTM C1113-90. The following table 1 shows the flame retardant and thermal conductive properties of the nylon flame retardant and thermal conductive composite materials according to examples 1, 2 and 3.

Table 1: performance comparison data of the flame-retardant and heat-conductive composite materials of examples 1-3 with pure nylon 6 resin

In example 1, BN (10%) and Al₂O₃(20%) Total addition amount30 percent, the limit oxygen index of the composite material reaches 37.5 percent, the UL-94 flame retardant test reaches V-0 level, and the heat conductivity reaches 0.751W/m.K^-1Compared with pure nylon 6, the heat conductivity coefficient is improved by nearly 4 times. In the examples 2 and 3, the thermal conductivity and the flame retardant property of the composite material are improved along with the increase of the content of the filler, and the thermal conductivity reaches 1.127W/m.K at most^-1The limiting oxygen index is improved to 43.7 percent; these test results all prove that the composite design is rational and correct and that the strategy of bonding the flame retardant to the surface of the thermally conductive particles by chemical reaction is correct.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.

Claims

1. The flame-retardant heat-conducting nylon composite material consists of nylon resin, an antioxidant, boron nitride modified by melamine salt flame retardant and aluminum oxide, and is characterized in that: wherein the raw material components have the following mass percentages:

49-97.5% of nylon resin;

1-20% of boron nitride modified by melamine salt flame retardant;

1-30% of aluminum oxide modified by melamine salt flame retardant;

0.5-1% of antioxidant.

2. The nylon flame-retardant heat-conductive composite material as claimed in claim 1, wherein: the addition amount of boron nitride of the surface modification flame retardant is 1-20 wt% of the mass fraction of the composite system; the addition amount of the aluminum oxide of the surface modification flame retardant is 1-30 wt% of the mass fraction of the composite system.

3. The nylon flame-retardant heat-conductive composite material as claimed in claim 1, wherein: the addition amount of boron nitride of the surface modification flame retardant is 10-20 wt% of the mass fraction of the composite system; the addition amount of the aluminum oxide of the surface modification flame retardant is 20-30 wt% of the mass fraction of the composite system.

4. The nylon flame-retardant heat-conductive composite material as claimed in claim 1, wherein: the addition amount of boron nitride of the surface modification flame retardant is 1-10 wt% of the mass fraction of the composite system; the addition amount of the aluminum oxide of the surface modification flame retardant is 1-10 wt% of the mass fraction of the composite system.

5. The nylon flame-retardant heat-conductive composite material as claimed in claim 1, wherein: the addition amount of boron nitride of the surface modification flame retardant is 8-15 wt% of the mass fraction of the composite system; the addition amount of the aluminum oxide of the surface modification flame retardant is 10-20 wt% of the mass fraction of the composite system.

6. The nylon flame-retardant heat-conducting composite material as claimed in any one of claims 1 to 5, wherein: the raw material components by mass percentage are as follows:

49-75% of nylon resin;

10-20% of boron nitride modified by melamine salt flame retardant;

10-20% of aluminum oxide modified by melamine salt flame retardant;

0.5-1% of antioxidant.

7. The nylon flame-retardant heat-conducting composite material as claimed in any one of claims 1 to 5, wherein: the raw material components by mass percentage are as follows:

80-97.5% of nylon resin;

1-10% of boron nitride modified by melamine salt flame retardant;

1-18% of aluminum oxide modified by melamine salt flame retardant;

0.5-1% of antioxidant.

8. The nylon flame-retardant heat-conducting composite material as claimed in any one of claims 1 to 5, wherein: the raw material components by mass percentage are as follows:

70-80% of nylon resin;

8-15% of boron nitride modified by melamine salt flame retardant;

11.5-20% of aluminum oxide modified by melamine salt flame retardant;

0.5-1% of antioxidant.

9. A method for preparing the nylon flame-retardant heat-conducting composite material as claimed in claim 1, which is characterized in that: the method comprises the following steps:

3) uniformly dispersing the prepared aluminum oxide pellets of the surface modified melamine salt flame retardant, the prepared boron nitride of the surface modified melamine salt flame retardant, the prepared nylon resin slices and the prepared antioxidant to obtain a mixed base material;

4) adding the obtained mixed base material into a double-screw extruder, and carrying out melt blending and grain cutting through the extruder to obtain granules of the composite material; the processing temperature is 220-280 ℃, and the rotating speed is set to be 70-120 r/min;

5) the obtained granules are subjected to injection molding or hot press molding to prepare the nylon-boron nitride-aluminum oxide flame-retardant heat-conducting composite material; the injection molding or hot press molding temperature is 220-285 ℃.

10. The preparation method of the nylon flame-retardant heat-conducting composite material as claimed in claim 9, wherein the preparation method comprises the following steps:

in the process 1), adopting alumina pellets with the diameter of 1-30 mu m to graft a silane coupling agent KH-560 on the surface of the alumina pellets, and bonding a melamine salt flame retardant to obtain the melamine salt flame retardant modified alumina pellets;

in the process 2), hexagonal boron nitride with the particle size of 1-30 mu m and melamine salt are blended and ball-milled, so that the surface of the hexagonal boron nitride is grafted with the melamine salt flame retardant;

the nylon resin is nylon 6 or nylon 66 or alloy resin of two kinds of nylon; the melamine salt flame retardant is at least one of melamine urate, melamine phosphate and melamine sulfate; the antioxidant comprises one or more of an antioxidant 1010, an antioxidant 1076 and an antioxidant 1098.