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

Abstract

The present invention discloses a halogen-free flame-retardant polyamide composition, a preparation method thereof and an application. The halogen-free flame-retardant polyamide composition comprises the following components calculated by weight: 30-80 parts of polyamide resin; 10-40 parts of glass fiber; 10-30 parts of halogen-free flame retardant; 0.1-3 parts of zinc-containing compound; the melting point of the zinc-containing compound is ≤600 °C; the halogen-free flame retardant is dialkyl phosphite. By adding an inorganic zinc-containing compound with a specific melting point, the present invention can be ionized at the flame temperature to generate zinc ions, which can coordinate with the polyamide resin and the halogen-free flame retardant, so as to avoid the phenomenon of dripping during combustion and does not affect the fluidity of the polyamide composition.

Description

Technical Field

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

[0002] Polyamide materials are widely used in engineering plastics. They have excellent heat resistance, solvent resistance, mechanical and processing properties, and are widely used in fields such as electronics and electrical appliances, rail transit, power tools, household appliances, and sports equipment. At present, the halogen-free flame retardants applied to glass fiber reinforcement mainly include two basic systems: one is red phosphorus; the other is the phosphorus-nitrogen flame retardant system. However, when the halogen-free flame-retardant polyamide material reinforced with glass fiber is subjected to a flame retardancy test, the problem of flame retardancy failure often occurs due to dripping. To solve this problem, it is common in the prior art to add an anti-dripping agent such as polytetrafluoroethylene to improve the anti-dripping effect of the material. However, this method will reduce the fluidity of the system, resulting in a lack of glue phenomenon during the injection molding process of the composition, and it is expensive.

[0003] Therefore, there is still a need in the art to develop a halogen-free flame-retardant polyamide composition with good anti-dripping effect and good fluidity. Summary of the Invention

[0004] The purpose of the present invention is to overcome the defects existing in the above-mentioned prior art and provide a halogen-free flame-retardant polyamide composition with good anti-dripping performance and fluidity.

[0005] Another object of the present invention is to provide a preparation method of the halogen-free flame-retardant polyamide composition.

[0006] Another object of the present invention is to provide the application of the halogen-free flame-retardant polyamide composition in new energy connectors and energy storage connectors.

[0007] To achieve the above object, the present invention is implemented by adopting the following technical solutions:

[0008] A halogen-free flame-retardant polyamide composition, comprising the following components calculated by weight:

[0009]

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

[0011] The present invention provides a halogen-free flame-retardant polyamide composition, in which a zinc compound with a melting point not exceeding 600 °C is added. Generally, the flame temperature is 500-600 °C. The melting point of the zinc compound will be ionized below the flame temperature, and the generated metal ions will coordinate with the polyamide resin and dialkyl hypophosphite, thereby slowing down the dripping during combustion and achieving the anti-dripping effect. Moreover, the addition of the zinc compound does not affect the fluidity of the polyamide composition, and it can be well formed during subsequent processing.

[0012] In the present invention, the melting point of the zinc compound does not exceed 600 °C, and specifically, it can 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 compound in the present invention, such as but not limited to bromide ions, chloride ions, iodide ions, sulfate ions, acetate ions, carbonate ions, basic carbonate ions, octanoate ions, nitrite ions, carboxylate ions. Zinc compounds with a melting point not exceeding 600 °C in the art can all achieve the present invention. Zinc compounds with a melting point not exceeding 600 °C include but are not limited to one or several of zinc bromide, zinc chloride, zinc iodide, zinc sulfate, zinc acetate, zinc carbonate, basic zinc carbonate, zinc octanoate, zinc nitrite, zinc carboxylate.

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

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

[0015] Further, based on the sum of the weights of the polyamide resin and dialkyl hypophosphite, the zinc compound accounts for 0.09 wt% - 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%, etc.

[0016] Further, the halogen-free flame-retardant polyamide composition includes the following components calculated by weight:

[0017]

[0018] Further, the dialkyl hypophosphite is one or several of aluminum methyl ethyl hypophosphite, aluminum diethyl hypophosphite, zinc diethyl hypophosphite or titanium diethyl hypophosphite.

[0019] In the halogen-free flame-retardant polyamide composition, the content of the 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.

[0020] Furthermore, the polyamide resin is a semi-aromatic polyamide and / or an aliphatic polyamide.

[0021] 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, PA12I.

[0022] The aliphatic polyamide is selected from one or more of PA6, PA66, PA610, PA612, PA1010, PA1012, PA1212, PA11, PA12.

[0023] 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, while ensuring the anti-dripping performance of the prepared halogen-free flame-retardant polyamide composition, the processing performance of the material can be further improved.

[0024] Furthermore, the relative viscosity of the polyamide resin is 2.1 to 2.4.

[0025] Specifically, the relative viscosity of the polyamide resin is measured according to ISO 307-2017.

[0026] Furthermore, the glass fiber includes chopped rovings of A-, E-, C-, D-, S-, R-glass fibers, and the cross-sectional shape of the glass fiber is one of circular, elliptical or square.

[0027] Furthermore, 0.1 to 1 part of antioxidant is further included in the above halogen-free flame-retardant polyamide composition.

[0028] In the present invention, common antioxidants can be selected, including one or several of hindered phenol antioxidants, phosphite antioxidants, diphenylamine antioxidants, copper salt antioxidants or thioether antioxidants.

[0029] Specifically, the hindered phenol antioxidant is one or more of N, N'-hexamethylenebis(3,5-di-tert-butyl-4-hydroxyphenylpropionamide) (Irganox 1098), pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (Irganox 1010), triethylene glycol bis-3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate (Iragnox 259), n-octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (Iragno 1076), or spiroglycol bis[β-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate] (ADK AO-80).

[0030] The phosphite antioxidant is one or more of 2,4-di-tert-butylphenol (Irganox 168), bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite (PEP-36), or 627A.

[0031] The diphenylamine antioxidant is 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine.

[0032] The copper salt antioxidant is a mixture of 8:1:1 K / Cu / ZnBLEND or KI / CuI.

[0033] The thioether antioxidant is one or more of distearyl thiodipropionate, dilauryl thiodipropionate, or pentaerythritol tetrakis(3-laurylthiopropionate).

[0034] The present invention protects a method for preparing the above-mentioned halogen-free flame-retardant polyamide composition, which includes the following steps:

[0035] The polyamide resin, glass fiber, halogen-free flame retardant, and zinc-containing compound are melt-blended and extruded into pellets to obtain the halogen-free flame-retardant composition.

[0036] Further, the extrusion granulation is carried out in a twin-screw extruder.

[0037] Further, 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, the temperature of the ninth zone is 260 - 280 °C, and the screw speed of the twin-screw extruder is 300 - 500 revolutions per minute.

[0038] The present invention protects the application of the above-mentioned halogen-free flame-retardant polyamide composition in new energy connectors and energy storage connectors.

[0039] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0040] The present invention provides a halogen-free flame-retardant polyamide composition. A zinc compound with a melting point ≤ 600 °C is added to the polyamide composition. At a normal flame temperature, the zinc compound will be ionized to generate zinc ions, so that the zinc ions can coordinate with the polyamide resin and the halogen-free flame retardant, thereby avoiding the dripping of the melt during combustion, and this anti-dripping method has no obvious influence on the fluidity of the composition. Specific Embodiments

[0041] The present invention will be further described below in conjunction with specific embodiments, but the embodiments do not limit the present invention in any form. Unless otherwise specified, the raw material reagents used in the embodiments of the present invention are raw material reagents purchased conventionally.

[0042] Raw materials used in the embodiments and comparative examples of the present invention:

[0043] Polyamide resin:

[0044] Polyamide resin 1: PA66 U2501, with a relative viscosity of the resin of 2.1, purchased from Invista;

[0045] Polyamide resin 2: PA66 U3600 NC01, with a relative viscosity of the resin of 2.4, purchased from Invista;

[0046] Polyamide resin 3: PA66 U4800 NC01, with a relative viscosity of the resin of 2.7, purchased from Invista;

[0047] Polyamide resin 4: PA6 HY-2500A, with a relative viscosity of the resin of 2.5, purchased from Xinhui Meida;

[0048] Glass fiber: ECS10-30-568H, purchased from China National Bluestar (Group) Co., Ltd.;

[0049] Halogen-free flame retardant:

[0050] Flame retardant 1: Aluminum diethylphosphinate, LFR-8003, purchased from Jiangsu Lister New Materials Co., Ltd.;

[0051] Flame retardant 2: Red phosphorus masterbatch, FR9950T, purchased from Tongcheng Xinde New Materials Co., Ltd.;

[0052] Zinc compound:

[0053] Zinc acetate: Melting point is 237 °C;

[0054] Zinc chloride: Melting point is 283 °C;

[0055] Zinc hydroxycarbonate: Melting point 300 °C;

[0056] Zinc bromide: The melting point is 394 °C;

[0057] Zinc phosphate: The melting point is 900 °C;

[0058] Zinc sulfide: The melting point is 1700 °C;

[0059] Sodium acetate: The melting point is 324 °C;

[0060] Polytetrafluoroethylene: X-010, purchased from Guangzhou Huigui Composite Materials Co., Ltd.;

[0061] Antioxidant: Antioxidant 1098; The antioxidant is commercially available, and the same antioxidant is used in the parallel experiments of the examples and comparative examples.

[0062] Examples 1 to 10 and Comparative Examples 1 to 6

[0063] According to the formulations in Tables 1 to 2, prepare the halogen-free flame-retardant polyamide composition according to the following preparation method:

[0064] Put the polyamide resin, glass fiber, halogen-free flame retardant and zinc-containing compound into a high-speed mixer and mix for 1 to 2 minutes at a rotation speed of 600 to 800 revolutions per minute, and then put it into a twin-screw extruder for melt blending and extrusion granulation to obtain the halogen-free flame-retardant polyamide composition; the temperature of the first zone of the twin-screw extruder is 180 to 200 °C, the temperature of the second zone is 250 to 270 °C, the temperature of the third zone is 260 to 280 °C, the temperature of the fourth zone is 265 to 285 °C, the temperature of the fifth zone is 265 to 285 °C, the temperature of the sixth zone is 265 to 285 °C, the temperature of the seventh zone is 260 to 280 °C, the temperature of the eighth zone is 260 to 280 °C, the temperature of the ninth zone is 260 to 280 °C, and the screw rotation speed of the twin-screw extruder is 300 to 500 revolutions per minute.

[0065] Table 1 Dosages of each component in the halogen-free flame-retardant polyamide composition in Examples 1 to 7 (parts by weight)

[0066]

[0067] Table 2 Dosages 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)

[0068]

[0069]

[0070] Performance testing

[0071] 1. Test method

[0072] Perform performance testing on the halogen-free flame-retardant polyamide compositions prepared in Examples 1 to 10 and Comparative Examples 1 to 6 above:

[0073] (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, and the thickness of the test specimen was 1.5 mm.

[0074] (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, and the test conditions were 280 °C / 2.16 kg.

[0075] 2. Test results

[0076] The performance test results of the halogen-free flame-retardant polyamide compositions prepared in each example and comparative example are shown in Table 3.

[0077] Table 3 Performance test results of Examples 1-10 and Comparative Examples 1-6

[0078]

[0079]

[0080] As can be seen from Table 3, the melt flow rate of the halogen-free flame-retardant polyamide compositions prepared in each example of the present invention is in the range of 15-46 g / 10 min. Within this range, the halogen-free flame-retardant polyamide composition has good processability; and there is no melt dripping during combustion, it has good flame-retardant performance, the self-extinguishing time does not exceed 3.3 s, and the self-extinguishing time of most examples does not exceed 2.6 s.

[0081] As can be seen from Comparative Example 1 and Comparative Example 2, when the melting point of the selected zinc-containing compound is higher than 600 °C, there is still a melt dripping phenomenon in the prepared halogen-free flame-retardant polyamide composition. This is because when the melting point of the added zinc-containing compound is above the flame temperature, ionization cannot occur, and it cannot coordinate with the polyamide resin and the flame retardant, thus unable to achieve the anti-dripping effect.

[0082] As can be seen from Comparative Example 3, when other metal compounds are selected to replace the zinc-containing compound, even if the melting point does not exceed 600 °C, there is still a melt dripping phenomenon in the prepared halogen-free flame-retardant polyamide composition. This is because sodium element does not have a similar coordination ability and cannot prevent dripping through coordination.

[0083] As can be seen from Comparative Example 4, when polytetrafluoroethylene is selected to replace the zinc-containing compound, although there is no melt dripping phenomenon in the prepared halogen-free flame-retardant polyamide composition, 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 there may be a phenomenon of insufficient glue.

[0084] It can be seen from Comparative Example 5 that when the zinc-containing compound is not added, although the halogen-free flame-retardant polyamide composition obtained has a relatively high melt flow rate, there is a melt dripping phenomenon and it will not self-extinguish.

[0085] It can be seen from Comparative Example 6 that when other halogen-free flame retardants are used to replace dialkyl phosphite, there will be a melt dripping phenomenon in the obtained halogen-free flame-retardant polyamide composition.

[0086] Obviously, the above-mentioned embodiments of the present invention are merely examples for clearly illustrating the present invention, rather than limiting the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation manners here. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the claims of the present invention.

Claims

1. A halogen-free flame-retardant polyamide composition, characterized in that, Comprising the following components by weight parts: Polyamide resin 30 - 80 parts; Glass fiber 10 - 40 parts; Halogen-free flame retardant 10 - 30 parts; Zinc-containing compound 0.1 - 3 parts; The melting point of the zinc-containing compound is 150 - 550 °C; the zinc-containing compound is one or more of zinc bromide, zinc chloride, zinc acetate or basic zinc carbonate; 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 halogen-free flame-retardant polyamide composition according to claim 1, wherein, based on the sum of the weights of the polyamide resin and the dialkyl hypophosphite, the zinc-containing compound accounts for 0.09 wt% - 7.5 wt%.

4. The halogen-free flame-retardant polyamide composition according to claim 1, wherein The dialkyl hypophosphite is one or more of aluminum methyl ethyl hypophosphite, aluminum diethyl hypophosphite, zinc diethyl hypophosphite or titanium diethyl hypophosphite.

5. 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.

6. The halogen-free flame-retardant polyamide composition according to claim 1, wherein It further comprises 0.1 - 1 part of antioxidant.

7. The halogen-free flame-retardant polyamide composition according to claim 6, characterized in that, The antioxidant is one or more of hindered phenol antioxidants, phosphite antioxidants, diphenylamine antioxidants, copper salt antioxidants or thioether antioxidants.

8. The preparation method of the halogen-free flame-retardant polyamide composition according to any one of claims 1 to 7, characterized in that, Including the following steps: Melting and blending the polyamide resin, glass fiber, halogen-free flame retardant and zinc-containing compound, and extruding and pelletizing to obtain the halogen-free flame-retardant polyamide composition.

9. Use of the halogen-free flame-retardant polyamide composition according to any one of claims 1 - 7 in new energy connectors and energy storage connectors.

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