WO2024066970A1 - Halogen-free flame-retardant semi-aromatic polyamide composite material, preparation method therefor, and use thereof - Google Patents

Abstract

Provided are a halogen-free flame-retardant semi-aromatic polyamide composite material, a preparation method therefor, and use thereof, which belong to the technical field of polymer material modification. The halogen-free flame-retardant semi-aromatic polyamide composite material comprises the following components in parts by weight: 35-50 parts of a semi-aromatic polyamide resin, 10-22 parts of a dialkyl hypophosphite flame retardant, 15-50 parts of a reinforcing material, and 0.2-2 parts of a carbonic acid compound. The semi-aromatic polyamide resin comprises any one of PA10T, PA10T/106, PA9T and PA12T. The amine-carboxyl ratio of the semi-aromatic polyamide resin is 1.02-1.08. The mass ratio of the carbonic acid compound to the dialkyl hypophosphite flame retardant is 1:(9-90). With no impact on foamability and its mechanical properties, the product provided also features low corrosivity, V-0 halogen-free flame retardance, and resistance to yellowing, and meets SMT process requirements. In addition, the added carbonic acid compound is inexpensive and easily available, and the preparation method is simple, and facilitates actual production.

Description

Halogen-free flame-retardant semi-aromatic polyamide composite material and preparation method and application thereof Technical Field

The invention belongs to the technical field of polymer material modification, and in particular relates to a halogen-free flame-retardant semi-aromatic polyamide composite material and a preparation method and application thereof.

Background technique

In recent years, with the high density and miniaturization of electronic products, lead-free surface mount technology (SMT) has become an important assembly method. Its application requires components to withstand high temperatures of 250-280°C. Traditional engineering plastics such as PA66 and PBT cannot meet this requirement at all, so high-temperature resistant engineering plastics came into being. Semi-aromatic polyamide (PPA) is widely used in the connector field because of its high melting point, high heat deformation temperature, high strength and other advantages.

As a general halogen-free flame retardant, dialkyl phosphinates not only have good flame retardant properties, small addition amounts, and little effect on the physical and electrical properties of the base resin, but also dialkyl phosphinate flame retardant materials have the characteristics of less smoke generation and higher CTI when burning than halogen flame retardants, and are highly valued by the industry, especially the electrical and electronic industry. At the same time, the temperature resistance of dialkyl phosphinate flame retardants is better than that of other halogen-free flame retardants on the market (such as red phosphorus, melamine polyphosphate and melamine cyanurate salt), and is the first choice for halogen-free flame retardants for semi-aromatic polyamides, and is commonly used in semi-aromatic polyamides such as PA10T, PA6T, PA9T and PA4T.

However, dialkyl phosphinates flame retard semi-aromatic polyamides. Due to the high extrusion/processing temperature of semi-aromatic polyamides, dialkyl phosphinates are easily decomposed into acidic substances such as dialkyl phosphinic acid and aluminum phosphate. Among them, dialkyl phosphinic acid is often used as a metal extractant, especially for substances such as iron, titanium, nickel, cadmium and cobalt. This is mainly because dialkyl phosphinic acid is easy to complex with metal elements to achieve the extraction effect, thereby eventually corroding the screw. At present, the conventional measures to solve the problem of screw corrosion caused by halogen-free flame retardant high-temperature nylon are: optimizing the screw material, and even coating the screw/mold surface, but this can only delay corrosion and it is difficult to achieve the purpose of "curing the root cause", and it also increases the manufacturing cost. On the other hand, polyamide is prone to "yellowing" after high-temperature oxidation because the amide bond is a chromophore. The acidic substances produced by dialkyl phosphinates during the extrusion/processing process will cause the nylon chain to break, exacerbating the yellowing phenomenon during the reflow soldering process. Simply adding antioxidants is difficult to achieve the yellowing resistance effect in the SMT process.

Summary of the invention

The purpose of the present invention is to overcome the deficiencies of the above-mentioned prior art and provide a halogen-free flame-retardant semi-aromatic polyamide composite material with low corrosion, reflow resistance, yellowing resistance and excellent mechanical properties, as well as a preparation method and application thereof.

To achieve the above-mentioned purpose, the technical scheme adopted by the present invention is: a halogen-free flame-retardant semi-aromatic polyamide composite material, comprising the following components in parts by weight: 35-50 parts of a semi-aromatic polyamide resin, 10-22 parts of a dialkyl hypophosphite flame retardant, 15-50 parts of a reinforcing material, and 0.2-2 parts of a carbonate compound; the semi-aromatic polyamide resin comprises any one of PA10T, PA10T/106, PA9T, and PA12T, the molar ratio of amine groups to carboxyl groups (amine-carboxyl ratio) in the semi-aromatic polyamide resin is 1:(1.02-1.08), and the mass ratio of the carbonate compound to the dialkyl hypophosphite flame retardant is carbonate compound: flame retardant = 1:(9-90).

The halogen-free flame-retardant semi-aromatic polyamide composite material provided by the present invention is prepared by adding a carbonate compound and limiting the mass ratio of the carbonate compound to a dialkyl hypophosphite flame retardant. When a semi-aromatic polyamide resin with a certain amine-carboxyl ratio is used as a matrix resin, the obtained halogen-free flame-retardant semi-aromatic polyamide composite material has low corrosivity, V-0 halogen-free flame retardancy, meets the requirements of an SMT process, and has less yellowing after the SMT process. This is because when a semi-aromatic polyamide resin with an amine-carboxyl ratio of 1: (1.02-1.08) is used as a matrix resin, the added carbonate compound can react with the dialkyl hypophosphite flame retardant, thereby reducing the corrosivity of the product and also reducing the yellowing phenomenon of the product.

As a preferred embodiment of the halogen-free flame-retardant semi-aromatic polyamide composite material of the present invention, the mass ratio of the carbonate compound to the dialkyl hypophosphite flame retardant is carbonate compound: dialkyl hypophosphite flame retardant = 1: (9-30).

Preferably, the mass ratio of the carbonate compound to the dialkyl hypophosphite flame retardant is carbonate compound: dialkyl hypophosphite flame retardant = 1:18.

The inventors have found through research that when the mass ratio of the carbonate compound to the dialkyl hypophosphite flame retardant is within the above-mentioned mass ratio, especially when the mass ratio of the carbonate compound to the dialkyl hypophosphite flame retardant is 1:18, the obtained composite material has more excellent low corrosion characteristics, yellowing resistance and better mechanical properties.

As a preferred embodiment of the halogen-free flame-retardant semi-aromatic polyamide composite material of the present invention, the semi-aromatic polyamide resin includes PA10T or PA9T.

The inventors have found through research that when the preferred semi-aromatic polyamide resin is PA10T or PA9T, the amide bond density of such resin is low, so the yellowing resistance and mechanical properties of the obtained product can achieve a balanced and better effect, and has excellent blistering resistance.

As a preferred embodiment of the halogen-free flame-retardant semi-aromatic polyamide composite material of the present invention, the carbonate compound includes any one of sodium carbonate, potassium carbonate, magnesium carbonate and calcium carbonate.

Preferably, the carbonate compound is calcium carbonate.

The inventors have found that by preferably using the above-mentioned carbonate compounds, especially calcium carbonate, it is possible to ensure that the yellowing resistance, low corrosion and mechanical properties of the product are all within an excellent range.

As a preferred embodiment of the halogen-free flame-retardant semi-aromatic polyamide composite material of the present invention, the flame retardant includes at least one of diethyl aluminum phosphinate, diethyl zinc phosphinate, methyl ethyl aluminum phosphinate, ethyl butyl aluminum phosphinate or ethyl hexyl aluminum phosphinate.

Preferably, the flame retardant is aluminum diethylphosphinate.

As a preferred embodiment of the halogen-free flame-retardant semi-aromatic polyamide composite material of the present invention, the semi-aromatic polyamide resin includes a diamine unit and a diacid unit; the diamine unit is derived from at least one monomer of an aliphatic diamine having 9 to 12 carbon atoms; and the diacid unit is derived from 45 to 100 mol % of an aromatic dicarboxylic acid and 0 to 55 mol % of an aliphatic dicarboxylic acid.

Preferably, the aliphatic diamine is selected from at least one of 1,9-nonanediamine, 1,10-decanediamine, 1,11-undecanediamine, 1,12-dodecanediamine, 2,2,4-trimethyl-1,6-hexanediamine, 2,4,4-trimethyl-1,6-hexanediamine, 2-methyl-1,8-octanediamine or 5-methyl-1,9-nonanediamine; the aromatic dicarboxylic acid is selected from terephthalic acid, isophthalic acid, 2 -methyl terephthalic acid, 2,5-dichloroterephthalic acid, 2,6-naphthalene dicarboxylic acid, 1,4-naphthalene dicarboxylic acid, 4,4'-biphenyl dicarboxylic acid or 2,2'-biphenyl dicarboxylic acid; the aliphatic dicarboxylic acid is selected from at least one of 1,4-succinic acid, 1,6-hexanedicarboxylic acid, 1,8-octanedioic acid, 1,9-nonanedioic acid, 1,10-decanedioic acid, 1,11-undecanedioic acid or 1,12-dodecane dioic acid.

As a preferred embodiment of the halogen-free flame retardant semi-aromatic polyamide composite material of the present invention, the reinforcing material includes at least one of glass fiber, carbon fiber, asbestos fiber, wollastonite fiber, ceramic fiber, potassium titanate whisker, basic magnesium sulfate whisker, silicon carbide whisker, aluminum borate whisker, silicon dioxide, aluminum silicate, silicon oxide, titanium dioxide, talc, wollastonite, diatomaceous earth, clay, kaolin, spherical glass, mica, and gypsum.

As a preferred embodiment of the halogen-free flame-retardant semi-aromatic polyamide composite material of the present invention, the halogen-free flame-retardant semi-aromatic polyamide composite material further comprises 0.3-1.0 parts of an antioxidant.

Preferably, the halogen-free flame-retardant semi-aromatic polyamide composite material further comprises 0.5 parts of an antioxidant.

The inventors have found that by adding an antioxidant, it can, to a certain extent, have a synergistic effect with carbonate compounds, more significantly reduce the yellowing phenomenon of the product, and improve the yellowing resistance of the product; especially when the amount of the antioxidant added is 0.5 parts, the mechanical properties of the product are not reduced on the basis of improving the yellowing resistance.

As a preferred embodiment of the halogen-free flame-retardant semi-aromatic polyamide composite material of the present invention, the antioxidant includes a hindered phenol antioxidant or a phosphite antioxidant.

Preferably, the antioxidant includes at least one of 1,3-benzenediamide-N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl), β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, N,N'-(hexane-1,6-diyl)bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionamide], 1,3,5-tris(3,5-di-tert-butyl-4-spasmodylbenzene)2,4,6-trimethylbenzene or 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzene)1,3,5-triazine-2,4,6-(1H,3H,5H)trione.

Preferably, the antioxidant is N,N'-(hexane-1,6-diyl)bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide].

In addition, the present invention also provides a method for preparing the halogen-free flame-retardant semi-aromatic polyamide composite material, which comprises the following steps: adding a semi-aromatic polyamide resin and a carbonate compound to an extruder through a main feeding port, adding a reinforcing material to the extruder through a first side feeding port, adding a dialkyl hypophosphite flame retardant to the extruder through a second side feeding port, melt blending, cooling, air drying, and granulating to obtain a halogen-free flame-retardant semi-aromatic polyamide composite material.

As a preferred embodiment of the preparation method of the present invention, the temperature of the melt blending is 250-350°C.

As a preferred embodiment of the preparation method of the present invention, when the components contain an antioxidant, the preparation method comprises the following steps: adding a semi-aromatic polyamide resin, a carbonate compound and an antioxidant to an extruder through a main feeding port, adding a reinforcing material to the extruder through a first side feeding port, adding a dialkyl hypophosphite flame retardant to the extruder through a second side feeding port, melt blending at a temperature of 250-350°C, cooling, air drying, and granulating to obtain a halogen-free flame retardant semi-aromatic polyamide composite material.

In addition, the present invention also provides an application of the halogen-free flame-retardant semi-aromatic polyamide composite material in the preparation of a light strip bracket, an LED reflector bracket, and electronic products that require an SMT process.

Compared with the prior art, the present invention has the following beneficial effects:

(1) The halogen-free flame-retardant semi-aromatic polyamide composite material provided by the present invention is prepared by adding carbonation The invention discloses a halogen-free flame retardant semi-aromatic polyamide composite material, wherein the mass ratio of the semi-aromatic polyamide composite material to the dialkyl hypophosphite flame retardant is 1: (9-90), and the halogen-free flame retardant semi-aromatic polyamide composite material is 1: (1.02-1.08) as the matrix resin. The halogen-free flame retardant semi-aromatic polyamide composite material has the characteristics of low corrosion, V-0 halogen-free flame retardancy, yellowing resistance and meets the requirements of the SMT process without affecting the foaming property and mechanical properties. The value of the yellowing resistance obtained is below 3.0DE, the value of the low corrosion performance is below 3.06%, and the weight loss rate of the steel sheet is below 138-150MPa. When the mass ratio of the carbonate compound to the dialkyl hypophosphite flame retardant is further preferably 1: (1.02-1.08), the halogen-free flame retardant semi-aromatic polyamide composite material has the characteristics of low corrosion, V-0 halogen-free flame retardancy, yellowing resistance and meets the requirements of the SMT process without affecting the foaming property and mechanical properties. (9-30), the obtained yellowing resistance value is below 2.6DE, the steel sheet weight loss rate of the low corrosion performance value is below 2.56%, and the tensile strength is between 138-150MPa; especially when the mass ratio of the carbonate compound to the dialkyl hypophosphite flame retardant is 1:18, the obtained comprehensive performance is optimal, wherein the steel sheet weight loss rate is 2.10%, the yellowing value is 2.12DE, and the tensile strength is 147MPa; when the semi-aromatic polyamide resin is further preferably PA10T or PA9T, the obtained yellowing resistance value is below 2.43DE, the steel sheet weight loss rate of the low corrosion performance value is below 2.40%, and the tensile strength is between 142-150MPa;

(2) The present invention can also further improve the yellowing resistance and low corrosion resistance of the product to a certain extent by adding an antioxidant to produce a synergistic effect with the carbonate compound. When the antioxidant is further added, the yellowing resistance value obtained is below 1.9DE, the weight loss rate of the steel sheet for the low corrosion performance is below 2.13%, and the tensile strength is between 144-150MPa;

(3) The carbonate compound and antioxidant raw materials added in the present invention are cheap and easily available, and the preparation method provided by the present invention is simple and easy to produce in practice.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a diagram of the evaluation machine nozzle used in the corrosion evaluation process in the effect example, a is a real picture, b is a cross-sectional view of the machine nozzle;

FIG2 is a diagram showing the situation in which no foaming occurs in the foaming test in the effect example;

FIG. 3 is a diagram showing the foaming condition in the foaming test in the effect example.

Detailed ways

In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art and can be obtained commercially.

The raw materials used in the following examples and comparative examples are as follows:

Semi-aromatic polyamide resin 1: PA10T-1, amine-carboxyl ratio of 1:1.02, homemade, diamine unit is decanediamine, diacid unit is terephthalic acid;

Semi-aromatic polyamide resin 2: PA10T-2, amine-carboxyl ratio of 1:1.05, homemade, diamine unit is decanediamine, diacid unit is terephthalic acid;

Semi-aromatic polyamide resin 3: PA10T-3, amine-carboxyl ratio of 1:1.08, homemade, diamine unit is decanediamine, diacid unit is terephthalic acid;

Semi-aromatic polyamide resin 4: PA10T-4, amine-carboxyl ratio of 1:1.00, homemade, diamine unit is decanediamine, diacid unit is terephthalic acid;

Semi-aromatic polyamide resin 5: PA10T-5, amine-carboxyl ratio of 1:1.10, homemade, diamine unit is decanediamine, diacid unit is terephthalic acid;

Semi-aromatic polyamide resin 6: PA10T/106, amine-carboxyl ratio of 1:1.05, homemade, diamine unit is decanediamine, diacid unit is terephthalic acid and adipic acid, wherein the molar ratio of terephthalic acid to adipic acid is 90:10;

Semi-aromatic polyamide resin 7: PA9T, amine-carboxyl ratio of 1:1.05, homemade, diamine unit is 1,9-nonanediamine, diacid unit is terephthalic acid;

Semi-aromatic polyamide resin 8: PA12T, amine-carboxyl ratio of 1:1.05, homemade, diamine unit is dodecanediamine, diacid unit is terephthalic acid;

Semi-aromatic polyamide resin 9: PA6T/66, amine-carboxyl ratio of 1:1.05, homemade, diamine unit is hexamethylenediamine, diacid unit is terephthalic acid and adipic acid, wherein the molar ratio of terephthalic acid to adipic acid is 60:40;

Flame retardant 1: aluminum diethylphosphinate, OP1230, Clariant;

Flame retardant 2: zinc diethylphosphinate, PFR1210, Changzhou Hongyu Chemical Co., Ltd.;

Reinforcement: Glass fiber, PREFORMAX 789, Owens-Corning;

Carbonate 1: Sodium carbonate, S111737, Shanghai Aladdin Biochemical Technology Co., Ltd.;

Carbonate 2: potassium carbonate, P111558, Shanghai Aladdin Biochemical Technology Co., Ltd.;

Carbonate 3: magnesium carbonate, M112906, Shanghai Aladdin Biochemical Technology Co., Ltd.;

Carbonate 4: calcium carbonate, C111985, Shanghai Aladdin Biochemical Technology Co., Ltd.;

Antioxidant: N,N'-(hexane-1,6-diyl)bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide], B183020, Shanghai Aladdin Biochemical Technology Co., Ltd.;

Capping agent: benzoic acid, commercially available.

The preparation method of the embodiment is as follows:

(1) Preparation of semi-aromatic polyamide resin: add measured diamine units and diacid units into a 20L autoclave, add 2‰ (total mass) of 1098 antioxidant and 1‰ (total mass) of sodium hypophosphite catalyst, the amount of end-capping agent is 0.02 times the molar amount of aromatic dicarboxylic acid unit, and the amine-carboxyl ratio is 1.00-1.10. After the addition is completed, evacuate and replace the gas with nitrogen, heat to a predetermined temperature of 230-240°C, and maintain a constant pressure of 2.9-3.1MPa by removing the formed water. After the reaction is completed, release the pressure to normal pressure to obtain a prepolymer. The prepolymer is solid-phase thickened in a rotary drum at 240-250°C, and the semi-aromatic polyamide resin can be obtained after 1-3 hours of thickening;

(2) adding a semi-aromatic polyamide resin and a carbonate compound into an extruder through a main feeding port (if an antioxidant is added in the embodiment, the antioxidant, the semi-aromatic polyamide resin and the carbonate compound are added into the extruder together through the main feeding port; if not added, only the semi-aromatic polyamide resin and the carbonate compound are added accordingly), adding a reinforcing material into the extruder through a first side feeding port, and adding a flame retardant into the extruder through a second side feeding port, melt blending at 250-350° C., cooling, air drying, and granulation to obtain a halogen-free flame-retardant semi-aromatic polyamide composite material.

The preparation method of the comparative example is consistent with the preparation method of the embodiment except that the components indicated in Table 1 and Table 2 are changed, and the sources of the same components are the same.

Examples 1-9 and Comparative Examples 1-7

The component contents (parts by weight) of Examples 1-9 and Comparative Examples 1-7 are shown in Table 1;

Table 1

Examples 10-18 and Comparative Examples 8-10

The component contents (parts by weight) of Examples 10-18 and Comparative Examples 8-10 are shown in Table 2;

Table 2

Effect example

The halogen-free flame-retardant semi-aromatic polyamide composite materials prepared in Examples 1-18 and Comparative Examples 1-10 were subjected to performance tests; wherein the relevant test reference standards or methods are as follows:

(1) Flame retardant grade

Using the UL94 combustion standard, the standard strip specimen size is 125±5mm long and 13.0±0.5mm wide. Thickness is 0.8±0.15mm. The samples can be cut, injection molded, etc. to ensure the same density. Two groups of 5 samples are treated at 23±2℃, 50±5%, for at least 48 hours. The other two groups of 5 samples are pre-treated by conditioning in a 70+1℃ oven for 168 hours, placing in a desiccator, and cooling at room temperature for at least 4 hours.

Experimental test records: a) Flame burning time after the first flame application, t1; b) Flame burning time after the second flame application, t2; c) Flameless burning time after the second flame application, t3; d) Whether the sample has a flameless combustion propagation fixture after combustion; e) Whether the burning drippings ignite the absorbent cotton; Specifically, the judgment basis is shown in Table 3;

table 3

(2) Corrosion assessment

A corrosion evaluation machine nozzle is designed (as shown in Figure 1), in which the green part (marked as part A) is a replaceable steel sheet. The polyamide compound of the embodiment or comparative example is injection molded into a 60*60*2mm square sheet on an injection molding machine, with a melting temperature of 330°C, a mold temperature of 120°C, a shot rate of 75%, a shot pressure of 50%, and continuous injection molding of 5000 pieces. The weight loss rate of the steel sheet is calculated by weighing and comparing the mass difference before and after the steel sheet is injected, and the specific weight loss rate of the steel sheet = (M _before - M _after ) / M _before * 100%, which is used to judge the corrosion resistance of the polyamide compound. The greater the loss, the greater the weight loss rate of the steel sheet, indicating that the corrosion is stronger, and vice versa.

(3) Yellowing test

The polyamide composite material of the embodiment or comparative example was dried at 120°C for 4 hours and then injection molded into a 80*50*2mm test piece. The L/a/b value of the test piece was tested, and then the test piece was placed in the SER-710A equipment of Unisplendour Sun East Technology (Shenzhen) Co., Ltd. and heated from room temperature to 150°C in 45 seconds, from 150°C to 200°C in 135 seconds, and from 260°C at a maximum temperature rise rate of 3°C/s. The temperature was cooled to room temperature at a rate of 6°C/s. Then the L/a/b value after reflow was tested, and the color difference (DE) before and after reflow was calculated according to Formula 1. The larger the value, the more serious the yellowing.

DE＝√(( _Lfront - _Lback ) ² +( _afront - _aback ) ² +( _bfront - _bback ) ² ).

(4) Tensile strength test

The polyamide composite material of the embodiment or comparative example was dried at 120°C for 4 hours and then tested by injection molding according to international standards. The tensile strength test was performed on the sample with a thickness of 4.0 mm according to ISO 527-2-2012 standard.

(5) Foaming test

The polyamide composite material of the embodiment or comparative example was dried at 120°C for 4 hours and then injection molded into a 60*60*1mm square plate, and then immersed in 23°C water for 24 hours for testing. The test piece was placed in the SER-710A equipment of Unisplendour Sun East Technology (Shenzhen) Co., Ltd., and heated from room temperature to 150°C in 45 seconds, from 150°C to 200°C in 135 seconds, and heated to 260°C at a maximum temperature rise rate of 3°C/s, wherein the time above 255°C was 20-40s, and then cooled to room temperature at a maximum temperature drop rate of 6°C/s, and the test piece was taken out to observe whether the test piece had blistering; Figure 2 shows the case of no blistering; Figure 3 shows the case of blistering.

The performance parameters obtained from the test are shown in Table 4;

Table 4

It can be seen from Examples 1-18 that within the scope of the technical solution given in the present invention, the obtained halogen-free flame retardant semi-aromatic polyamide composite material has excellent yellowing resistance and low corrosion resistance, wherein the value of the yellowing resistance is below 3.0DE, and the value of the low corrosion performance is below 3.06% of the weight loss rate of the steel sheet; and it can also maintain relatively good mechanical properties, with a tensile strength between 138-150MPa; at the same time, the flame retardant grade is V-0 and does not blister.

It can be seen from Examples 1-4 and Comparative Examples 1-2 that the mass ratio of the carbonate compound to the dialkyl hypophosphite flame retardant will affect the corrosion resistance, yellowing resistance and tensile strength of the product; it can be seen from Examples 1-4 that when the mass ratio of the dialkyl hypophosphite flame retardant to the carbonate compound is between 1:(9-90), the comprehensive performance of the obtained product is excellent, especially when the mass ratio of the dialkyl hypophosphite flame retardant to the carbonate compound is 1:18, the comprehensive performance is optimal, the weight loss rate of the steel sheet is 2.10%, the yellowing value is 2.12DE, and the tensile strength is 147MPa; it can be seen from Comparative Examples 1-2 that when the content of the component is within the range, but the mass ratio of the dialkyl hypophosphite flame retardant to the carbonate compound is not within the scope of the present invention, When too much dialkyl hypophosphite flame retardant is added, the yellowing resistance of the obtained product is significantly reduced, and the mechanical properties and corrosion resistance also show a certain downward trend; when too little dialkyl hypophosphite flame retardant is added, the flame retardant performance of the obtained product is significantly reduced.

It can be seen from Examples 5-6 that when the number of added components is changed, within the scope of the present invention, the comprehensive performance of the obtained products is relatively excellent; it can be seen from Comparative Examples 3-4 of Example 3 that when the mass ratio of dialkyl hypophosphite flame retardant and carbonate compound is kept at 1:18, but the content of the components is not within the range given in the present invention, the performance of the obtained products shows a downward trend.

It can be seen from Example 3 and Examples 7-9 that when an antioxidant is further added on the basis of Example 3, the yellowing resistance of the product will be further improved to a certain extent. As the content of the antioxidant continues to increase, the improvement effect on the yellowing resistance is weakened, and the mechanical properties of the product will be reduced. Therefore, the preferred amount of antioxidant added is 0.5 parts. It can be seen from Example 8 and Comparative Examples 5-7 that when the dialkyl hypophosphite flame retardant is reduced, the obtained material has low corrosivity and excellent yellowing resistance, but it does not have flame retardancy; when the carbonate compound and the antioxidant are reduced or the carbonate compound is reduced, the corrosivity of the obtained product is enhanced, and the yellowing resistance is weakened; it shows that adding an antioxidant on the basis of adding a carbonate compound can synergistically improve the yellowing resistance of the product and ensure the low corrosivity of the product, but the antioxidant cannot replace the carbonate compound.

It can be seen from Example 3, Examples 10-11 and Comparative Examples 8-9 that the amine-carboxyl ratio of the semi-aromatic polyamide resin will have a significant impact on the performance of the product. When the amine-carboxyl ratio of the semi-aromatic polyamide resin is too large or too small, the yellowing resistance of the obtained product decreases and the corrosiveness increases. It can be seen from Example 3, Examples 12-14 and Comparative Example 10 that the type of semi-aromatic polyamide resin will also affect the performance of the product.

It can be seen from Examples 10 and 15 that the selection of dialkyl hypophosphite flame retardant will also have some influence on the performance of the product.

It can be seen from Example 3 and Examples 16-18 that changes in the type of carbonate compounds will affect the corrosion resistance, yellowing resistance and mechanical properties of the product. When the selected carbonate compound is sodium carbonate, potassium carbonate or magnesium carbonate, the corrosion resistance, yellowing resistance and mechanical properties of the obtained product show a significant downward trend to a certain extent compared to calcium carbonate.

Finally, it should be noted that the above embodiments are intended to illustrate the technical solutions of the present invention rather than to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, ordinary technicians in the field Those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims (10)

1. A halogen-free flame-retardant semi-aromatic polyamide composite material, characterized in that it comprises the following components in parts by weight: 35-50 parts of a semi-aromatic polyamide resin, 10-22 parts of a dialkyl hypophosphite flame retardant, 15-50 parts of a reinforcing material, and 0.2-2 parts of a carbonate compound;

   The semi-aromatic polyamide resin includes any one of PA10T, PA10T/106, PA9T, and PA12T;

   The molar ratio of amine group to carboxyl group in the semi-aromatic polyamide resin is 1:(1.02-1.08);

   The mass ratio of the carbonate compound to the dialkyl hypophosphite flame retardant is carbonate compound: dialkyl hypophosphite flame retardant = 1: (9-90).
2. The halogen-free flame-retardant semi-aromatic polyamide composite material according to claim 1 is characterized in that the mass ratio of the carbonate compound to the dialkyl hypophosphite flame retardant is carbonate compound: dialkyl hypophosphite flame retardant = 1: (9-30).
3. The halogen-free flame-retardant semi-aromatic polyamide composite material according to claim 1, characterized in that the semi-aromatic polyamide resin comprises PA10T or PA9T.
4. The halogen-free flame-retardant semi-aromatic polyamide composite material according to claim 1, characterized in that the carbonate compound comprises any one of sodium carbonate, potassium carbonate, magnesium carbonate and calcium carbonate.
5. The halogen-free flame-retardant semi-aromatic polyamide composite material according to claim 1 is characterized in that the dialkyl hypophosphite flame retardant includes at least one of diethyl aluminum phosphinate, diethyl zinc phosphinate, methyl ethyl aluminum phosphinate, ethyl butyl aluminum phosphinate or ethyl hexyl aluminum phosphinate.
6. The halogen-free flame-retardant semi-aromatic polyamide composite material according to claim 1, characterized in that the reinforcing material includes at least one of glass fiber, carbon fiber, asbestos fiber, wollastonite fiber, ceramic fiber, potassium titanate whisker, basic magnesium sulfate whisker, silicon carbide whisker, aluminum borate whisker, silicon dioxide, aluminum silicate, silicon oxide, titanium dioxide, talc, wollastonite, diatomaceous earth, clay, kaolin, spherical glass, mica, and gypsum.
7. The halogen-free flame-retardant semi-aromatic polyamide composite material according to claim 1, characterized in that it also includes 0.3-1.0 parts of an antioxidant.
8. The halogen-free flame-retardant semi-aromatic polyamide composite material according to claim 7, characterized in that the antioxidant comprises a hindered phenol antioxidant or a phosphite antioxidant.
9. The method for preparing a halogen-free flame-retardant semi-aromatic polyamide composite material according to any one of claims 1 to 8, characterized in that the preparation method comprises the following steps: adding a semi-aromatic polyamide resin and a carbonate compound to an extruder through a main feeding port, adding a reinforcing material to the extruder through a first side feeding port, adding a dialkyl hypophosphite flame retardant to the extruder through a second side feeding port, melt blending, cooling, air drying, and granulating to obtain a halogen-free flame-retardant semi-aromatic polyamide composite material.
10. Application of the halogen-free flame-retardant semi-aromatic polyamide composite material as described in any one of claims 1 to 8 in the preparation of light strip brackets, LED reflector brackets, and electronic products that require SMT processes.