CN111662538B - Low-smoke-density high-performance halogen-free flame-retardant reinforced PBT (polybutylene terephthalate) compound and preparation method thereof - Google Patents

Abstract

The invention discloses a low-smoke density high-performance halogen-free flame-retardant reinforced PBT compound and a preparation method thereof. The low-smoke density high-performance halogen-free flame-retardant reinforced PBT compound comprises the following components in parts by weight: 36.5-58.7 parts of PBT, 14-16.5 parts of organic aluminum hypophosphite, 3.5-7 parts of melamine polyphosphate, 10-30 parts of glass fiber, 0.3-0.8 part of epoxy resin, 3-8 parts of melamine cyanurate salt, 3-5 parts of molybdate, 2-4 parts of reactive smoke suppressant and 0.2-0.5 part of antioxidant. The low-smoke-density high-performance halogen-free flame-retardant reinforced PBT compound is prepared by mutually matching PBT, organic aluminum hypophosphite, melamine polyphosphate, glass fiber, cyanuric acid melamine salt, molybdate, a reactive smoke suppressant and other components, and has excellent smoke suppression performance and good mechanical property.

Description

Low-smoke-density high-performance halogen-free flame-retardant reinforced PBT (polybutylene terephthalate) compound and preparation method thereof

Technical Field

The invention relates to the technical field of engineering plastics, and particularly relates to a low-smoke-density high-performance halogen-free flame-retardant reinforced PBT compound and a preparation method thereof.

Background

Plastic materials are generally produced with a large amount of smoke in the combustion process, and can cause environmental pollution and great harm to human bodies. In recent years, with the development of plastic flame retardant technology, low-smoke flame retardant has become a new direction for the development of flame retardant plastics. The demand for low smoke flame retardancy in the industries of rail transit, building materials, cables and the like is more obvious and standardized, and the industries have clear requirements that plastic parts in application must reach the smoke density level 2 or above (namely, the smoke density Ds max is less than or equal to 300 according to ISO 5659-2) required by EN45545-2 standard.

Polybutylene terephthalate (PBT) is polymerized by terephthalic acid and butanediol through polycondensation, has a melting point of 225-235 ℃, and belongs to a crystalline material. The PBT material which is most widely used in the market at present is a product which is reinforced by glass fiber and modified in flame retardance, and is widely applied to lighting lamps, cooling fans, connectors, coil frameworks, electric appliance shells and other electronic and electrical components. However, the common flame-retardant reinforced modified PBT material can generate a large amount of smoke in the combustion process, and the smoke density Ds max of a 1mm sample plate tested according to the ISO5659-2 standard is generally at the level of 500-600, which is far from the basic requirement of the industry. Therefore, in order to apply the PBT material in the industries, low-smoke density modification is required.

At present, relatively few patents and researches are carried out on the aspect of low-smoke density PBT, and the halogen-containing flame-retardant reinforced PBT material on the market is still the mainstream at present due to factors such as price and performance. However, with the increasing environmental protection concerns of the european union and countries around the world and the continuous introduction of various environmental regulations in recent years, the trend of non-halogenation of plastic materials has not been reversible. Chinese patent application CN109575561A discloses a low-smoke density halogen-free flame-retardant PC/PBT alloy material and a preparation method thereof, but the system is an atypical PBT material, the PBT resin in the alloy is low in proportion, and the material is not a glass fiber reinforced system, the mechanical property level of the material is low, and the application range of the material is greatly limited.

Therefore, there is still a need to develop a halogen-free flame retardant reinforced PBT compound with low smoke density and high performance.

Disclosure of Invention

In order to overcome the defects of high smoke density and low mechanical property of the halogen-free flame-retardant PBT material in the prior art, the invention provides the low-smoke-density high-performance halogen-free flame-retardant reinforced PBT compound, which has excellent smoke suppression performance and maintains good mechanical property.

The invention also aims to provide a preparation method of the low-smoke density high-performance halogen-free flame-retardant reinforced PBT compound.

In order to solve the technical problems, the invention adopts the technical scheme that:

a low-smoke density high-performance halogen-free flame-retardant reinforced PBT compound comprises the following components in parts by weight:

36.5-58.7 parts of PBT, 14-16.5 parts of organic aluminum hypophosphite, 3.5-7 parts of melamine polyphosphate, 10-30 parts of glass fiber, 0.3-0.8 part of epoxy resin, 3-8 parts of Melamine Cyanurate (MCA), 3-5 parts of molybdate, 2-4 parts of reactive smoke suppressant and 0.2-0.5 part of antioxidant;

the molecular formula of the reactive smoke suppressant is C₃₉H₃₃O₈N₃P₂。

The reactive smoke suppressant used in the invention is a plastic smoke suppressant SL-18 of Shandong Huaen rubber and plastic new material Co.

Preferably, the molybdate is ammonium octamolybdate.

The molecular formula of the reactive smoke suppressant is C₃₉H₃₃O₈N₃P₂It has excellent heat stability, water resistance, light ageing resistance, no toxicity and no precipitate.

The inventor researches and discovers that under the combined action of MCA, molybdate and a reactive smoke inhibitor, the smoke amount of the compound is remarkably reduced in the combustion process, and the compound can successfully pass the test requirement that the smoke density Ds max of ISO5659-2 standard is less than or equal to 300 (the thickness of a sample is 1 mm); and the addition of the three smoke inhibitors can not cause obvious loss of the mechanical property of the PBT compound. MCA reduces the concentration of incombustibles by dilution, thereby reducing smoke density; the molybdate promotes intermolecular crosslinking reaction to generate carbide at the initial stage of thermal decomposition during plastic combustion, so that combustible components are reduced to achieve the smoke suppression effect; the smoke suppression mechanism of the reactive smoke suppressant is to promote further combustion of smoke dust, thereby reducing the smoke generation.

The invention uses the compound of organic aluminum hypophosphite and melamine polyphosphate as the halogen-free flame retardant compound. Preferably, the compounding weight ratio of the organic aluminum hypophosphite to the melamine polyphosphate is 5: 1-2: 1.

Preferably, the PBT has an intrinsic viscosity of 0.8-1.2 dL/g (25 ℃). The viscosity range of the PBT resin enables the PBT compound of the invention to have better comprehensive performance.

Preferably, the glass fibers are treated with a coupling agent.

The use of glass fibers treated with a coupling agent can significantly improve the mechanical properties of the PBT composite of the invention.

More preferably, the coupling agent is a blend of N- (beta-aminoethyl) -gamma-aminopropyltrimethoxysilane, gamma-methacryloxypropyltrimethoxysilane, and isopropylbis (methacryloyl) isostearyl titanate in a weight ratio of 1: 2: 1.

The epoxy resin can be phenolic aldehyde epoxy resin and bisphenol A type glycidyl ether. Preferably, the epoxy resin is bisphenol a type glycidyl ether.

Preferably, the epoxy equivalent of the epoxy resin is 2500-3100 g/eq.

The addition of epoxy resin can improve the performance stability of the PBT compound.

Preferably, the antioxidant is a hindered phenol antioxidant.

More preferably, the hindered phenolic antioxidant is beta (3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid octadecyl ester (antioxidant 1076) or 1,3, 5-tris (4-tert-butyl-3-hydroxy-2, 6-dimethylbenzyl) -1,3, 5-triazine-2, 4,6- (1H,3H,5H) -trione (antioxidant 1790).

The antioxidant 1076 has the advantages of good compatibility, high antioxidant performance, no coloring, no pollution, washing resistance, small volatility and the like; the antioxidant 1790 has excellent precipitation resistance, and can ensure that the product has better thermal stability and longer service life.

The invention also provides a preparation method of the low-smoke density high-performance halogen-free flame-retardant reinforced PBT compound, which comprises the following steps:

s1, mixing molybdate, a reactive smoke suppressant, epoxy resin and an antioxidant to obtain a mixture A;

s2, mixing organic aluminum hypophosphite, melamine polyphosphate and MCA to obtain a mixture B;

and S3, adding the PBT, the glass fiber, the mixture A obtained in the step S1 and the mixture B obtained in the step S2 into a double-screw extruder, and mixing, dispersing, melt extruding and granulating to obtain the low-smoke-density high-performance halogen-free flame-retardant reinforced PBT compound.

Preferably, in the step S3 of the preparation method, the temperature of the twin-screw extruder in the first zone from the feeding port to the head is 200-230 ℃, the temperature of the second zone is 240-260 ℃, the temperature of the third zone is 235-255 ℃, the temperature of the fourth zone is 235-255 ℃, the temperature of the fifth zone is 235-255 ℃, the temperature of the sixth zone is 240-260 ℃, the temperature of the seventh zone is 240-260 ℃, the temperature of the eighth zone is 220-240 ℃, the temperature of the ninth zone is 220-240 ℃, the temperature of the tenth zone is 240-260 ℃, and the screw rotation speed of the twin-screw extruder is 200-450 rpm.

Compared with the prior art, the invention has the beneficial effects that:

the low-smoke-density high-performance halogen-free flame-retardant reinforced PBT compound is prepared by mutually matching PBT, organic aluminum hypophosphite, melamine polyphosphate, glass fiber, MCA, molybdate, a reactive smoke suppressant and other components, has excellent smoke suppression performance, can reach the smoke density of 2 or above (namely the smoke density Ds max is less than or equal to 300 according to ISO5659-2 test) required by EN45545-2 standard, and can maintain good mechanical properties.

Detailed Description

The present invention will be further described with reference to the following embodiments.

The starting materials in the examples are all commercially available, and are specified below:

PBT Jiangsu instrumentation chemical fiber GX111, intrinsic viscosity at 25 ℃ 0.7 dL/g;

jiangsu instrumented chemical fiber GX112 with intrinsic viscosity of 0.8dL/g at 25 ℃;

jiangsu characterization chemical fiber GX234 with intrinsic viscosity of 1.2dL/g at 25 ℃;

glass fiber taiwan bicheng gmbh HP 3786;

n- (beta-aminoethyl) -gamma-aminopropyltrimethoxysilane Hubeixin Rundchemie KH-792;

gamma-methacryloxypropyltrimethoxysilane Tsingtakuma Hecheng Chengcheng science KH-570;

new isopropyl di (methacryloyl) isostearyl titanate Nanjing Energer technology KR-7;

organic aluminum hypophosphite Exolite OP 1230, Leine chemical Co., Ltd;

melamine polyphosphate german basf Melapur 20070;

MCA-01 of MCA Sichuan province research and design institute of fine chemistry;

ammonium octamolybdate Guangzhou Edanda chemical FS-10;

zinc molybdate Henan Xin source chemical TP-35N;

a reactive smoke suppressant, namely a Shandonghua rubber plastic new material SL-18;

epoxy resin

YD-019 in national chemical industry, and epoxy equivalent of bisphenol A type glycidyl ether is 2500-3100 g/eq;

the epoxy equivalent of the baring petrochemical CYD-011 and the bisphenol A type glycidyl ether is 450-500 g/eq;

antioxidant 1076, taiwan double bond chemical CHINOX 1076;

antioxidant 1790 cyanohydrin 1790.

Reagents, methods and apparatus used in the present invention are conventional in the art unless otherwise indicated.

Examples 1 to 16

Embodiments 1-16 provide a low-smoke density high-performance halogen-free flame-retardant reinforced PBT composite, respectively.

In examples 1 to 16, the addition amounts of the components of the low-smoke density high-performance halogen-free flame-retardant reinforced PBT composite are shown in Table 1.

The PBT used in examples 1-13 and 16 is GX234, the PBT used in example 14 is GX112, and the PBT used in example 15 is GX 111.

TABLE 1 amounts (parts by weight) of each component added in examples 1 to 16

TABLE 1 addition of the components (in parts by weight) in examples 1 to 16

In examples 1-15, the preparation methods of the low smoke density high performance halogen-free flame retardant reinforced PBT compound are as follows:

s1, putting molybdate, a reactive smoke suppressant, epoxy resin and an antioxidant into a high-speed mixer, and mixing for 2-4 minutes at the rotating speed of 700-900 rpm to obtain a mixture A;

s2, placing organic aluminum hypophosphite, melamine polyphosphate and MCA into a high-speed mixer to be mixed for 2-4 minutes at the rotating speed of 600-800 rpm to obtain a mixture B;

s3, pretreating the glass fiber by using a blend of three coupling agents, namely N- (beta-aminoethyl) -gamma-aminopropyltrimethoxysilane, gamma-methacryloxypropyltrimethoxysilane and isopropyl di (methacryloyl) isostearoyl titanate (the blending weight ratio of the three is 1: 2: 1), so as to obtain pretreated glass fiber;

and S4, adding the PBT, the mixture A obtained in the step S1, the mixture B obtained in the step S2 and the pretreated glass fibers obtained in the step S3 into a double-screw extruder through a feeder respectively, and mixing, dispersing, melt extruding and granulating to obtain the low-smoke-density high-performance halogen-free flame-retardant reinforced PBT compound.

In step S4, the temperature of the twin-screw extruder in the first zone from the feeding port to the head is 200 to 230 ℃, the temperature of the second zone is 240 to 260 ℃, the temperature of the third zone is 235 to 255 ℃, the temperature of the fourth zone is 235 to 255 ℃, the temperature of the fifth zone is 235 to 255 ℃, the temperature of the sixth zone is 240 to 260 ℃, the temperature of the seventh zone is 240 to 260 ℃, the temperature of the eighth zone is 220 to 240 ℃, the temperature of the ninth zone is 220 to 240 ℃, the temperature of the tenth zone is 240 to 260 ℃, and the screw rotation speed of the twin-screw extruder is 200 to 450 rpm.

The preparation method of the low-smoke density high-performance halogen-free flame-retardant reinforced PBT compound of embodiment 16 is as follows:

s1, putting molybdate, a reactive smoke suppressant, epoxy resin and an antioxidant into a high-speed mixer, and mixing for 2-4 minutes at the rotating speed of 700-900 rpm to obtain a mixture A;

s2, placing organic aluminum hypophosphite, melamine polyphosphate and MCA into a high-speed mixer to be mixed for 2-4 minutes at the rotating speed of 600-800 rpm to obtain a mixture B;

and S3, adding the PBT, the mixture A obtained in the step S1, the mixture B obtained in the step S2 and the glass fiber into a double-screw extruder through a feeder respectively, and mixing, dispersing, melt extruding and granulating to obtain the low-smoke-density high-performance halogen-free flame-retardant reinforced PBT compound.

In step S3, the temperature of the twin-screw extruder in the first zone from the feeding port to the head is 200 to 230 ℃, the temperature of the second zone is 240 to 260 ℃, the temperature of the third zone is 235 to 255 ℃, the temperature of the fourth zone is 235 to 255 ℃, the temperature of the fifth zone is 235 to 255 ℃, the temperature of the sixth zone is 240 to 260 ℃, the temperature of the seventh zone is 240 to 260 ℃, the temperature of the eighth zone is 220 to 240 ℃, the temperature of the ninth zone is 220 to 240 ℃, the temperature of the tenth zone is 240 to 260 ℃, and the screw rotation speed of the twin-screw extruder is 200 to 450 rpm.

Comparative examples 1 to 7

Comparative examples 1 to 7 respectively provide a halogen-free flame-retardant reinforced PBT compound.

In comparative examples 1 to 6, the addition amount of the halogen-free flame-retardant reinforced PBT compound is shown in Table 2, and the preparation method is the same as that in examples 1 to 15.

The PBT used in comparative examples 1 to 6 was GX 234. Comparative example 7 is commercially available low smoke density halogen free flame retardant PBT with a glass fiber content of 30% by inspection.

TABLE 2 addition amounts (parts by weight) of respective components in comparative examples 1 to 6

Comparative example 1 differs from example 1 in that no MCA was added;

comparative example 2 differs from example 1 in that no molybdate was added;

comparative example 3 differs from example 1 in that no reactive smoke suppressant is added;

comparative example 4 differs from example 1 in that no MCA and molybdate were added, i.e. only the reactive smoke suppressant was added to the smoke suppressant;

comparative example 5 differs from example 1 in that no MCA, molybdate and reactive smoke suppressant are added, i.e. none of the three smoke suppressants are added;

comparative example 6 differs from example 1 in that the reactive smoke suppressant is added in an amount of 5 parts by weight.

Performance testing

The performance test of the low-smoke density high-performance halogen-free flame-retardant reinforced PBT compound or the commercially available low-smoke density halogen-free flame-retardant PBT prepared in the above examples and comparative examples is carried out, and the test method is as follows:

the test results of examples 1 to 16 are shown in Table 3.

Table 3 results of performance tests of examples 1 to 16

TABLE 3 results of performance tests of examples 1 to 16

As can be seen from Table 3, according to the results of the smoke density test, the smoke densities of examples 1-16 all have a Ds max of 200 or less under the action of the three smoke suppressants, and can reach a smoke density level of 2 or more (namely, the smoke density Ds max of 300 or less according to the ISO5659-2 test) required by the EN45545-2 standard.

Example 5 differs from example 1 in that the molybdate used in example 5 is zinc molybdate and the molybdate used in example 1 is ammonium octamolybdate. By comparing the results of the smoke density tests of example 5 and example 1, the smoke density of example 5 is Ds max 198 and the smoke density of example 1 is Ds max 179, indicating that the use of ammonium octamolybdate in the molybdate is more effective in suppressing smoke, so ammonium octamolybdate is preferred in the molybdate.

The difference between the example 9 and the example 1 is that the epoxy resin used in the example 9 is bisphenol A type glycidyl ether with the epoxy equivalent of 450-500 g/eq, the brand is Baoling CYD-011, the epoxy resin used in the example 1 is bisphenol A type glycidyl ether with the epoxy equivalent of 2500-3100 g/eq, and the brand is DOUD chemical YD-019. By comparing the test results of example 9 and example 1, the tensile strength, notched impact strength, flexural modulus of the PBT composite of example 9 are all reduced to some extent compared with example 1. This means that the PBT composite has better mechanical properties when a bisphenol A type glycidyl ether having an epoxy equivalent of 2500 to 3100g/eq is used, and therefore a bisphenol A type glycidyl ether having an epoxy equivalent of 2500 to 3100g/eq is preferable as the epoxy resin.

Example 15 differs from examples 1 and 14 in that example 15 used a PBT of GX234 having an intrinsic viscosity of 0.7dL/g at 25 ℃, example 1 used a PBT of GX234 having an intrinsic viscosity of 1.2dL/g at 25 ℃, example 13 used a PBT of GX112 having an intrinsic viscosity of 0.8dL/g at 25 ℃. The tensile strength, notched impact strength, flexural modulus test results of comparative examples 1, 14 and 15 show that the PBT composite of example 15 has a reduced index. Therefore, the intrinsic viscosity of PBT is preferably 0.8 to 1.2dL/g at 25 ℃. The test results of comparative examples 1 to 7 are shown in Table 4.

TABLE 4 comparative examples 1-7 Performance test results

As can be seen from the comparative example test results in Table 4, the smoke density of the PBT compound of comparative example 5 without any smoke suppressant is very high, Ds max > 500, compared with example 1. Compared with the comparative examples 1-4 and the example 1, when only one or two smoke inhibitors are added, the smoke inhibiting effect of the PBT composite still does not reach the low smoke density level required by the invention, namely three smoke inhibitors are required to be used cooperatively to achieve the high-efficiency smoke inhibiting effect. Meanwhile, the smoke density of the commercially available low-smoke-density halogen-free flame-retardant PBT does not reach Ds max which is less than or equal to 300. By comparing the test results of the comparative examples 1 to 5 with those of the example 1 on tensile strength, notch impact strength, bending strength and bending modulus, it is found that the mechanical properties of the PBT compound can reach a higher level by adding one or two smoke inhibitors or simultaneously adding three smoke inhibitors according to the technical scheme of the invention within the technical scheme of the invention. Compared with the PBT compound without the smoke suppressant, the mechanical property of the smoke suppressant is greatly maintained. Comparing the test results of the tensile strength, the notch impact strength, the bending strength and the bending modulus of the comparative example 6 with those of the example 1, the mechanical property of the PBT compound of the comparative example 6 is reduced to a certain extent. This shows that when the addition amount of the smoke suppressant exceeds the technical scheme of the invention, the mechanical property of the PBT compound is reduced, and the smoke suppressant is added according to the technical scheme of the invention, so that the performance of the PBT compound is not deteriorated.

It should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.

Claims (9)

1. The low-smoke density high-performance halogen-free flame-retardant reinforced PBT compound is characterized by comprising the following components in parts by weight: 36.5-58.7 parts of PBT, 14-16.5 parts of organic aluminum hypophosphite, 3.5-7 parts of melamine polyphosphate, 10-30 parts of glass fiber, 0.3-0.8 part of epoxy resin, 3-8 parts of melamine cyanurate salt, 3-5 parts of molybdate, 2-4 parts of a reactive smoke suppressant and 0.2-0.5 part of an antioxidant;

the molecular formula of the reactive smoke suppressant is C₃₉H₃₃O₈N₃P₂The reactive smoke suppressant is a plastic smoke suppressant SL-18 of Shandong Huaen rubber and plastic new material Co.Ltd;

the molybdate is ammonium octamolybdate.

2. The low-smoke density high-performance halogen-free flame-retardant reinforced PBT compound according to claim 1, wherein the weight ratio of the organic aluminum hypophosphite to the melamine polyphosphate is 5: 1-2: 1.

3. The low smoke density high performance halogen-free flame retardant reinforced PBT composite of claim 1, wherein the intrinsic viscosity of the PBT is 0.8-1.2 dL/g at 25 ℃.

4. The low smoke density high performance halogen-free flame retardant reinforced PBT composite of claim 1, wherein the glass fiber is treated with a coupling agent.

5. The low smoke density high performance halogen free flame retardant reinforced PBT composite of claim 4, wherein the coupling agent is a blend of N- (β -aminoethyl) - γ -aminopropyltrimethoxysilane, γ -methacryloxypropyltrimethoxysilane, and isopropyldi (methacryloyl) isostearyl titanate.

6. The low-smoke density high-performance halogen-free flame-retardant reinforced PBT compound as recited in claim 1, wherein the epoxy resin is bisphenol A glycidyl ether, and the epoxy equivalent is 2500-3100 g/eq.

7. The low smoke density high performance halogen-free flame retardant reinforced PBT composite of claim 1, wherein the antioxidant is a hindered phenol antioxidant.

8. The low smoke density high performance halogen-free flame retardant reinforced PBT composite of claim 7, wherein the hindered phenolic antioxidant is octadecyl beta (3,5 di-tert-butyl-4-hydroxyphenyl) propionate or 1,3, 5-tris (4-tert-butyl-3-hydroxy-2, 6-dimethylbenzyl) -1,3, 5-triazine-2, 4,6- (1H,3H,5H) -trione.

9. The preparation method of the low-smoke density high-performance halogen-free flame retardant reinforced PBT compound as claimed in any one of claims 1 to 8, which is characterized by comprising the following steps:

s1, mixing molybdate, a reactive smoke suppressant, epoxy resin and an antioxidant to obtain a mixture A;

s2, mixing organic aluminum hypophosphite, melamine polyphosphate and melamine cyanurate to obtain a mixture B;

and S3, adding the PBT, the glass fiber, the mixture A obtained in the step S1 and the mixture B obtained in the step S2 into a double-screw extruder, and mixing, dispersing, melt extruding and granulating to obtain the low-smoke-density high-performance halogen-free flame-retardant reinforced PBT compound.