Halogen-free flame-retardant polyamide composition, and preparation method therefor and use thereof

Abstract

A halogen-free flame-retardant polyamide composition, and a preparation method therefor and the use thereof. The halogen-free flame-retardant polyamide composition comprises the following components in parts by weight: 30-80 parts of a polyamide resin, 10-40 parts of glass fibers, 10-30 parts of a halogen-free flame retardant, and 0.1-3 parts of a zinc-containing compound, wherein the melting point of the zinc-containing compound is less than or equal to 600°C, and the halogen-free flame retardant is a dialkyl phosphinate salt. By adding an inorganic zinc-containing compound having a specific melting point, ionization will take place at a flame temperature to generate zinc ions, which are coordinated with the polyamide resin and the halogen-free flame retardant to prevent the phenomenon of molten droplets during the combustion process, and the flowability of the polyamide composition will not be affected.

Description

A halogen-free flame-retardant polyamide composition and its preparation method and application Technical Field

[0001] The present invention relates to the technical field of engineering plastics, and more particularly to a halogen-free flame-retardant polyamide composition, a preparation method thereof, and applications thereof. Background Art

[0002] Polyamide material is a widely used material in engineering plastics. It has excellent heat resistance, solvent resistance, mechanical and processing properties, and is widely used in the fields of electronics and electrical, rail transportation, power tools, home appliances, sports equipment, etc. At present, the halogen-free flame retardants used for glass fiber reinforcement mainly include two basic systems: one is red phosphorus; the other is a phosphorus-nitrogen flame retardant system. However, when the glass fiber reinforced halogen-free flame retardant polyamide material is subjected to flame retardant testing, it often fails to flame retardant due to dripping. In order to solve this problem, the prior art commonly uses the addition of anti-drip agents such as polytetrafluoroethylene to improve the anti-drip effect of the material, but this method will reduce the fluidity of the system, resulting in glue deficiency in the composition during the injection molding process, and it is expensive.

[0003] Therefore, there is a need in the art to develop a halogen-free flame retardant polyamide composition that has both good anti-dripping effect and good fluidity.

[0004] Summary of the Invention

[0005] The purpose of the present invention is to provide a halogen-free flame retardant polyamide composition in order to overcome the defects in the prior art. The polyamide composition has good anti-dripping performance and fluidity.

[0006] Another object of the present invention is to provide a method for preparing the halogen-free flame retardant polyamide composition.

[0007] Another object of the present invention is to provide an application of the halogen-free flame-retardant polyamide composition in new energy connectors and energy storage connectors.

[0008] To achieve the above objectives, the present invention adopts the following technical solutions:

[0009] A halogen-free flame-retardant polyamide composition comprises the following components calculated in parts by weight:

[0010] The melting point of the zinc-containing compound is ≤600° C.; the halogen-free flame retardant is dialkyl hypophosphite.

[0011] The present invention provides a halogen-free flame-retardant polyamide composition. A zinc-containing compound having a melting point not exceeding 600°C is added to the halogen-free flame-retardant polyamide composition. The zinc-containing compound, with a melting point below the flame temperature of 500-600°C, ionizes. The generated metal ions coordinate with the polyamide resin and dialkyl hypophosphite, thereby slowing dripping during combustion and achieving an anti-drip effect. Furthermore, the addition of the zinc-containing compound does not affect the fluidity of the polyamide composition, allowing for good molding during subsequent processing.

[0012] In the present invention, the melting point of the zinc-containing compound does not exceed 600°C, and can specifically be 550°C, 500°C, 450°C, 400°C, 350°C, 300°C, 250°C, 200°C, 150°C, 100°C, etc. It should be noted that there are no special requirements for the anions of the zinc-containing compound in the present invention, such as but not limited to bromide, chloride, iodide, sulfate, acetate, carbonate, basic carbonate, octanoate, nitrite, and carboxylate. All zinc-containing compounds with a melting point not exceeding 600°C in the art can realize the present invention. The zinc-containing compound with a melting point not exceeding 600°C includes but is not limited to one or more of zinc bromide, zinc chloride, zinc iodide, zinc sulfate, zinc acetate, zinc carbonate, basic zinc carbonate, zinc octanoate, zinc nitrite, and zinc carboxylate.

[0013] Furthermore, the melting point of the zinc-containing compound is 200-400°C.

[0014] Furthermore, the melting point of the zinc-containing compound is 220-300°C.

[0015] Furthermore, based on the total weight of the polyamide resin and the dialkyl hypophosphite, the zinc-containing compound accounts for 0.09 wt% to 7.5 wt%, for example, but not limited to, 0.1 wt%, 0.5 wt%, 1.0 wt%, 1.5 wt%, 2.0 wt%, 2.5 wt%, 3.0 wt%, 3.5 wt%, 4.0 wt%, 4.5 wt%, 5.0 wt%, 5.5 wt%, 6.0 wt%, 6.5 wt%, 7.0 wt%, and 7.5 wt%.

[0016] Furthermore, the halogen-free flame retardant polyamide composition comprises the following components calculated in parts by weight:

[0017] Furthermore, the dialkyl hypophosphite is one or more of methylethyl aluminum hypophosphite, diethyl aluminum hypophosphite, diethyl zinc hypophosphite or diethyl titanium hypophosphite.

[0018] In the halogen-free flame-retardant polyamide composition, the content of polyamide resin is not less than 28 wt %, for example but not limited to 30 wt %, 35 wt %, 40 wt %, 45 wt %, 50 wt %, 55 wt %, 60 wt %, etc.

[0019] Furthermore, the polyamide resin is semi-aromatic polyamide and / or aliphatic polyamide.

[0020] Specifically, the semi-aromatic polyamide is selected from one or more of PA6T / 66, PA6I, PA6T / 6I, PA6T / M5T, PA9T, PA9T / 66, PA10T, PA10T / 66, PA10T / 10I, PA10T / 1010, PA12T, and PA12I.

[0021] The aliphatic polyamide is selected from one or more of PA6, PA66, PA610, PA612, PA1010, PA1012, PA1212, PA11, and PA12.

[0022] The present invention has no special requirements for the relative viscosity of the polyamide resin. When the relative viscosity of the polyamide resin is 2.1 to 2.7, the anti-dripping performance of the prepared halogen-free flame retardant polyamide composition can be ensured while further improving the processing performance of the material.

[0023] Furthermore, the relative viscosity of the polyamide resin is 2.1 to 2.4.

[0024] Specifically, the relative viscosity of the polyamide resin is tested according to ISO 307-2017.

[0025] Furthermore, the glass fibers include chopped strands A-, E-, C-, D-, S-, and R-glass fibers, and the cross-sectional shape of the glass fibers is one of circular, elliptical, and square.

[0026] Furthermore, the halogen-free flame-retardant polyamide composition further comprises 0.1 to 1 parts of an antioxidant.

[0027] In the present invention, commonly used antioxidants can be selected, including one or more of hindered phenol antioxidants, phosphite antioxidants, diphenylamine antioxidants, copper salt antioxidants or thioether antioxidants.

[0028] Specifically, the hindered phenol antioxidant is one or more of N,N'-hexamethylenebis(3,5-di-tert-butyl-4-hydroxyphenylpropionamide (Irganox 1098), pentaerythritol tetrakis[1093,5-di-tert-butyl-4-hydroxyphenyl)propionate] (Irganox 1010), triethylene glycol bis-3-(3-tert-butyl-4-hydroxy-5-methylphenyl) propionate (Iragnox 259), β-(4-hydroxy-3,5-di-tert-butylphenyl) propionate n-octadecyl (Iragno 1076) or spiroethylene glycol bis[β-(3-tert-butyl-4-hydroxy-5-methylphenyl) propionate] (ADK AO-80).

[0029] The phosphite antioxidant is one or more of 2,4-di-tert-butylphenol (Irganox 168), bis(2,6-di-tert-butyl-4-methylphenyl) pentaerythritol phosphite (PEP-36) or 627A.

[0030] The diphenylamine antioxidant is 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine.

[0031] The copper salt antioxidant is a mixture of 8:1:1 K / Cu / ZnBLEND or KI / CuI.

[0032] The thioether antioxidant is one or more of distearyl thiodipropionate, dilauryl thiodipropionate or pentaerythritol dodecylthiopropionate.

[0033] The present invention provides a method for preparing the halogen-free flame-retardant polyamide composition, comprising the following steps:

[0034] The polyamide resin, glass fiber, halogen-free flame retardant and zinc-containing compound are melt-blended and extruded into granules to obtain a halogen-free flame retardant composition.

[0035] Furthermore, the extrusion granulation is carried out in a twin-screw extruder.

[0036] Furthermore, the temperature of zone one of the twin-screw extruder is 180-200°C, the temperature of zone two is 250-270°C, the temperature of zone three is 260-280°C, the temperature of zone four is 265-285°C, the temperature of zone five is 265-285°C, the temperature of zone six is ​​265-285°C, the temperature of zone seven is 260-280°C, the temperature of zone eight is 260-280°C, and the temperature of zone nine is 260-280°C, and the screw speed of the twin-screw extruder is 300-500 rpm.

[0037] The present invention protects the application of the above-mentioned halogen-free flame-retardant polyamide composition in new energy connectors and energy storage connectors.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] The present invention provides a halogen-free flame-retardant polyamide composition. A zinc-containing compound with a melting point of 600° C. is added to the polyamide composition. At a normal flame temperature, the zinc-containing compound is ionized to generate zinc ions, so that the zinc ions can be coordinated with the polyamide resin and the halogen-free flame retardant, thereby preventing the melt from dripping during combustion. This anti-dripping method has no obvious effect on the fluidity of the composition. DETAILED DESCRIPTION

[0040] The present invention will be further described below in conjunction with specific embodiments, but the examples do not limit the present invention in any form. Unless otherwise specified, the raw materials and reagents used in the examples of the present invention are conventionally purchased raw materials and reagents.

[0041] The raw materials used in the embodiments and comparative examples of the present invention are:

[0042] Polyamide resin:

[0043] Polyamide resin 1: PA66 U2501, resin relative viscosity 2.1, purchased from INVISTA;

[0044] Polyamide resin 2: PA66 U3600 NC01, resin relative viscosity 2.4, purchased from INVISTA;

[0045] Polyamide resin 3: PA66 U4800 NC01, resin relative viscosity is 2.7, purchased from INVISTA;

[0046] Polyamide resin 4: PA6 HY-2500A, resin relative viscosity 2.5, purchased from Xinhui Meida;

[0047] Glass fiber: ECS10-30-568H, purchased from China Jushi Co., Ltd.

[0048] Halogen-free flame retardants:

[0049] Flame retardant 1: diethyl aluminum hypophosphite, LFR-8003, purchased from Jiangsu Liside New Materials Co., Ltd.;

[0050] Flame retardant 2: red phosphorus masterbatch, FR9950T, purchased from Tongcheng Xinde New Materials Co., Ltd.

[0051] Zinc compounds:

[0052] Zinc acetate: melting point is 237°C;

[0053] Zinc chloride: melting point is 283°C;

[0054] Basic zinc carbonate: melting point 300℃;

[0055] Zinc bromide: melting point is 394°C;

[0056] Zinc phosphate: melting point is 900℃;

[0057] Zinc sulfide: melting point 1700℃;

[0058] Sodium acetate: melting point is 324°C;

[0059] Polytetrafluoroethylene: X-010, purchased from Guangzhou Huigui Composite Materials Co., Ltd.;

[0060] Antioxidant: Antioxidant 1098; the antioxidant is commercially available, and the parallel experiments in the examples and comparative examples all use the same antioxidant.

[0061] Examples 1 to 10 and Comparative Examples 1 to 6

[0062] According to the formula in Tables 1 and 2, a halogen-free flame retardant polyamide composition was prepared according to the following preparation method:

[0063] The polyamide resin, glass fiber, halogen-free flame retardant and zinc-containing compound are placed in a high-speed mixer and mixed for 1-2 minutes at a rotation speed of 600-800 rpm. The mixture is then placed in a twin-screw extruder for melt blending and extrusion granulation to obtain a halogen-free flame retardant polyamide composition. The temperature of the first zone of the twin-screw extruder is 180-200° C., the temperature of the second zone is 250-270° C., the temperature of the third zone is 260-280° C., the temperature of the fourth zone is 265-285° C., the temperature of the fifth zone is 265-285° C., the temperature of the sixth zone is 265-285° C., the temperature of the seventh zone is 260-280° C., the temperature of the eighth zone is 260-280° C., and the temperature of the ninth zone is 260-280° C. The screw speed of the twin-screw extruder is 300-500 rpm.

[0064] Table 1 Amount of each component in the halogen-free flame retardant polyamide composition of Examples 1 to 7 (parts by weight)

[0065] Table 2 Amount of each component in the halogen-free flame retardant polyamide composition in Examples 8 to 10 and Comparative Examples 1 to 6 (parts by weight)

[0066] Performance Testing

[0067] 1. Test Method

[0068] The halogen-free flame retardant polyamide compositions prepared in Examples 1 to 10 and Comparative Examples 1 to 6 were subjected to performance tests:

[0069] (1) Combustion performance test: The halogen-free flame retardant polyamide compositions prepared in the above examples and comparative examples were tested according to the UL94-2009 standard, with the test specimen thickness being 1.5 mm;

[0070] (2) Melt flow rate test: The halogen-free flame retardant polyamide compositions prepared in the above examples and comparative examples were tested according to the standard ISO 1133-1-2022, wherein the test conditions were 280° C. / 2.16 kg.

[0071] 2. Test results

[0072] The performance test results of the halogen-free flame retardant polyamide compositions prepared in the examples and comparative examples are shown in Table 3.

[0073] Table 3 Performance test results of Examples 1 to 10 and Comparative Examples 1 to 6

[0074] As can be seen from Table 3, the melt flow rate of the halogen-free flame retardant polyamide composition prepared in each embodiment of the present invention is 15 to 46 g / 10 min. Within this range, the halogen-free flame retardant polyamide composition has good processing performance; there is no melt dripping during combustion, and the composition has good flame retardant properties. The self-extinguishing time does not exceed 3.3 s, and the self-extinguishing time of most embodiments does not exceed 2.6 s.

[0075] It can be seen from Comparative Examples 1 and 2 that when the melting point of the selected zinc-containing compound is higher than 600°C, the obtained halogen-free flame-retardant polyamide composition still has the dripping phenomenon. This is because when the melting point of the added zinc-containing compound is above the flame temperature, it cannot be ionized and cannot be coordinated with the polyamide resin and the flame retardant, thus failing to achieve the anti-dripping effect.

[0076] It can be seen from Comparative Example 3 that when other metal compounds are used to replace the zinc-containing compound, even if the melting point does not exceed 600°C, the obtained halogen-free flame retardant polyamide composition still has the dripping phenomenon. This is because the sodium element does not have a similar coordination ability and cannot prevent dripping through coordination.

[0077] It can be seen from Comparative Example 4 that when polytetrafluoroethylene is used instead of the zinc-containing compound, the obtained halogen-free flame-retardant polyamide composition has no droplet phenomenon, but the melt flow rate is only 13 g / 10 min, the fluidity is reduced, the molding window will be shortened during the injection molding process, and glue shortage may occur.

[0078] It can be seen from Comparative Example 5 that when no zinc-containing compound is added, the prepared halogen-free flame-retardant polyamide composition has a high melt flow rate, but has a droplet phenomenon and is not self-extinguishing.

[0079] It can be seen from Comparative Example 6 that when other halogen-free flame retardants are used instead of dialkyl hypophosphite, the obtained halogen-free flame retardant polyamide composition will have a droplet phenomenon.

[0080] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A halogen-free flame-retardant polyamide composition, characterized in that: The composition comprises the following components calculated by weight: The melting point of the zinc-containing compound is ≤600° C.; the halogen-free flame retardant is dialkyl hypophosphite.

2. The halogen-free flame-retardant polyamide composition according to claim 1, characterized in that: The melting point of the zinc-containing compound is 200-400°C.

3. The halogen-free flame-retardant polyamide composition according to claim 1, characterized in that: The zinc-containing compound with a melting point of ≤600° C. is one or more of zinc bromide, zinc chloride, zinc iodide, zinc sulfate, zinc acetate, zinc carbonate, zinc octoate, zinc nitrite, basic zinc carbonate, and zinc carboxylate.

4. The halogen-free flame-retardant polyamide composition according to claim 1, characterized in that: The halogen-free flame-retardant polyamide composition according to claim 1, characterized in that the zinc compound accounts for 0.09wt% to 7.5wt% based on the sum of the weights of the polyamide resin and the dialkyl hypophosphite.

5. The halogen-free flame-retardant polyamide composition according to claim 1, characterized in that: The dialkyl hypophosphite is one or more of methylethyl aluminum hypophosphite, diethyl aluminum hypophosphite, diethyl zinc hypophosphite or diethyl titanium hypophosphite.

6. The halogen-free flame-retardant polyamide composition according to claim 1, characterized in that: The polyamide resin is semi-aromatic polyamide and / or aliphatic polyamide.

7. The halogen-free flame-retardant polyamide composition according to claim 1, characterized in that: It also includes 0.1 to 1 part of antioxidant.

8. The halogen-free flame-retardant polyamide composition according to claim 7, characterized in that: The antioxidant is one or more of a hindered phenol antioxidant, a phosphite antioxidant, a diphenylamine antioxidant, a copper salt antioxidant or a thioether antioxidant.

9. The method for preparing the halogen-free flame-retardant polyamide composition according to any one of claims 1 to 8, characterized in that: The following steps are involved: The polyamide resin, glass fiber, halogen-free flame retardant and zinc-containing compound are melt-blended and extruded to granulate to obtain a halogen-free flame-retardant polyamide composition.

10. Use of the halogen-free flame-retardant polyamide composition according to any one of claims 1 to 8 in new energy connectors and energy storage connectors.

Images