A halogen-free flame-retardant PPE / PA alloy and its preparation method and application

Abstract

This invention discloses a halogen-free flame-retardant PPE / PA alloy, comprising, by weight, the following components: polyphenylene ether and polyamide, a halogen-free flame retardant, and a toughening agent; wherein the halogen-free flame retardant is selected from at least one of zinc borate, zinc borate / phosphononitrile blend, and zinc borate / antimony oxide blend; wherein the weight ratio of polyphenylene ether to polyamide ranges from 1:(1-3.5); and the toughening agent is selected from any one or more of maleic anhydride-grafted styrene block copolymers and maleic anhydride-grafted ethylene-octene copolymers. This invention achieves a CTI rating of 0 and good dimensional stability through a specific polyphenylene ether to polyamide blend ratio. The flame retardant of this invention achieves halogen-free flame retardancy without precipitation, and the toughening agent improves low-temperature drop ball performance. Therefore, the PPE / PA alloy of this invention possesses halogen-free flame retardancy, a CTI rating of 0, minimal precipitation under high temperature and humidity, meets UL's low-temperature drop ball standard, and exhibits good dimensional stability, making it suitable for photovoltaic connectors.

Description

Technical Field

[0001] This invention relates to the field of polymer technology, and in particular to a halogen-free flame-retardant PPE / PA alloy, its preparation method, and its application. Background Technology

[0002] Polyphenylene oxide (PPE), as an amorphous engineering plastic, possesses excellent flame retardancy, acid and alkali resistance, high temperature resistance, damp heat resistance, and dimensional stability. However, due to its viscosity and internal stress, PPE is prone to stress cracking when exposed to oil, limiting its use in applications requiring high stress resistance and complex operating conditions. By incorporating poly(acetal) (PA) into PPE, leveraging nylon's excellent solvent resistance, toughness, and flowability, the resulting PPE / PA alloy significantly improves PPE's stress cracking resistance, thereby greatly expanding the application range of PPE materials.

[0003] Photovoltaic connectors are key components that connect various parts of a photovoltaic power generation system, such as modules, combiner boxes, controllers, and inverters. Therefore, they require high-performance materials. Key performance indicators for these materials include: halogen-free flame retardancy, CTI rating 0, minimal material precipitation under high temperature and humidity conditions to reduce corrosion of the connector's metals, and compliance with UL's low-temperature drop ball standard: 51mm diameter, 535g steel ball * 1.295m, -35℃ / 3h (UL).

[0004] However, existing flame-retardant systems used in PPE / PA alloys cannot simultaneously achieve the requirements of halogen-free and efflorescence resistance. For example, patent CN103865256B discloses a method for preparing flame-retardant PPE / PA using melamine and red phosphorus, but such flame retardants are prone to efflorescence under high temperature and humidity conditions, failing to meet the low efflorescence requirement for photovoltaic connector materials. Patent EP0448221B1 also discloses a method for preparing flame-retardant PPE / PA alloys using nylon and brominated styrene, but this method does not meet the halogen-free requirement for photovoltaic connectors. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned technical defects and provide a halogen-free flame-retardant PPE / PA alloy with a CTI rating of 0, low precipitation under high temperature and humidity, meeting UL's low-temperature drop ball standard, and good dimensional stability.

[0006] This invention is achieved through the following technical solution:

[0007] A halogen-free flame-retardant PPE / PA alloy, comprising the following components by weight:

[0008] 60-100 parts of polyphenylene ether and polyamide;

[0009] 9-15 parts of halogen-free flame retardant;

[0010] 3-12 parts toughening agent;

[0011] The halogen-free flame retardant is selected from at least one of zinc borate, zinc borate / phosphononitrile compound flame retardant, and zinc borate / antimony white compound flame retardant, wherein the weight ratio of zinc borate / phosphononitrile is (8-2):1, and the compounding ratio of zinc borate / antimony white is (8:2):1.

[0012] The weight ratio of polyphenylene ether to polyamide ranges from 1:(1-3.5).

[0013] The toughening agent is selected from any one or more of maleic anhydride-grafted styrene block copolymers and maleic anhydride-grafted ethylene-octene copolymers, wherein the grafting rate of maleic anhydride is 0.2-1 wt%.

[0014] The zinc borate content in the halogen-free flame-retardant PPE / PA alloy of this invention ranges from 6 to 13.3 parts.

[0015] The polyphenylene ether content in the halogen-free flame-retardant PPE / PA alloy of this invention ranges from 13.3 to 50 parts.

[0016] The polyphenylene ether of this invention is polymerized from 2,6-dimethylphenol or its derivatives. The intrinsic viscosity range of the polyphenylene ether of this invention, measured using an Ubbelohde viscometer in chloroform at 25°C, is 25-60 μm. 3 / g, with a preferred intrinsic viscosity of 35-45m 3 / g.

[0017] The polyamide is selected from at least one of aliphatic polyamides and semi-aromatic polyamides. The aliphatic polyamide resin is selected from PA66, PA46, PA610, PA612, PA56, PA510, PA512, PA910, PA912, PA913, PA914, PA915, PA616, PA936, PA1010, PA1012, PA1013, PA1014, PA1210, PA1212, PA1213, PA1214, PA614, PA613, PA615, PA616, etc.

[0018] The semi-aromatic polyamide is selected from PA MXD6, PA10T, PA10T1010, PA10T66, PA6T, PA6T66, PA9T, etc. Preferably, the halogen-free flame retardant contains only zinc borate and does not include other flame retardants.

[0019] The technical solution of this invention does not have a particular limitation on the average particle size of zinc borate, phosphononitrile, and antimony white. The purpose of this invention can be achieved when the average particle size is in the range of 0.1 to 10 μm. The average particle size is measured by a particle size analyzer.

[0020] Phosphazenes are selected from hexaphenoxycyclotriphosphazenes, phenoxypolyphosphazenes, and derivatives thereof. Preferably, the phosphazene is selected from hexaphenoxycyclotriphosphazenes. Specifically, phenoxypolyphosphazenes can be polydiphenoxyphosphazenes.

[0021] Preferably, the grafting rate of maleic anhydride in the toughening agent is 0.4-0.7 wt%.

[0022] The toughening agent of this invention can be a commercially available product or can be prepared in-house. The preparation method can be as follows: grafting ungrafted toughening agent, maleic anhydride, and initiator through a twin-screw extruder (screw temperature 150-180℃, length-to-diameter ratio greater than or equal to 40:1). The initiator is selected from at least one of dicumyl peroxide, di-tert-butyl peroxide, tert-butyl hydroperoxide, and cumyl peroxide. The amount of initiator added is 0.2-0.8 wt% of the total feed.

[0023] The grafting rate of maleic anhydride is tested by titration. The specific procedure is as follows: the graft is dissolved in xylene under reflux. After cooling, a certain amount of 0.05 mol / L potassium hydroxide-ethanol solution is added, and the mixture is heated under reflux for another 8 hours. Using 0.1% phenolphthalein solution as an indicator, the solution is titrated with 0.05 mol / L HCl-isopropanol solution while hot to the endpoint. The grafting rate G is calculated using the following formula:

[0024] G = (N1 × Vl - N2 × V2) × M ÷ w ÷ 10

[0025] In the formula: N1: KOH—equivalent concentration of ethanol solution, N;

[0026] V1: Volume of KOH ethanol solution, ml;

[0027] N2: Equivalent concentration of HCl-isopropanol solution, N;

[0028] V2: Volume of HCl-isopropanol solution, ml;

[0029] M: Equivalent mass of maleic anhydride, g;

[0030] w: Mass of the dried sample after extraction, in g.

[0031] The maleic anhydride-grafted styrene block copolymer is selected from at least one of maleic anhydride-grafted styrene-butadiene-styrene block copolymer, maleic anhydride-grafted styrene-ethylene / butene-styrene block copolymer, and maleic anhydride-grafted styrene-ethylene / propylene-styrene block copolymer.

[0032] In the PPE / PA alloy of this invention, the toughening agent accounts for 5-12 wt% of the total weight of the PPE / PA alloy.

[0033] The product also includes 0.1-2 parts by weight of antioxidant, wherein the antioxidant is selected from at least one of phenolic antioxidants, phosphite antioxidants, or metal passivators.

[0034] The preparation method of halogen-free flame-retardant PPE / PA alloy includes the following steps: according to the formula, the components are mixed evenly, and granulated by extrusion through a twin-screw extruder with a screw speed of 250-500 rpm and an extrusion temperature of 230-290℃ to obtain halogen-free flame-retardant PPE / PA alloy.

[0035] The application of halogen-free flame-retardant PPE / PA alloys in the manufacture of photovoltaic connectors.

[0036] The present invention has the following beneficial effects:

[0037] This invention, by using a specific PPE / PA alloy ratio and employing pure zinc borate or a zinc borate-based flame retardant, achieves V0 flame retardancy, effectively avoiding the surface whitening defect caused by conventional halogen-free flame retardants. Simultaneously, the PPE / PA alloy ratio of this invention allows the material to achieve a CTI rating of 0 while maintaining good dimensional stability. Furthermore, the use of a maleic anhydride-grafted toughening agent improves the compatibility of the resin matrix and further enhances the material's toughness, meeting the requirements for low-temperature drop ball performance at different temperatures. The resulting non-reinforced halogen-free flame-retardant PPE / PA alloy composition is highly suitable for use in the photovoltaic new energy field. Detailed Implementation

[0038] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0039] The raw materials used in this invention are sourced from the following sources:

[0040] PPE: PPE LXR040, Bluestar, intrinsic viscosity 39.5-41.5 cm⁻¹ 3 / g;

[0041] PA66: PA66 U3600 NC01, NVIDIA;

[0042] PA612: PA612 A170, Shandong Guangyin New Materials;

[0043] PA6T / 66: KFHP4, Zhuhai Wantong;

[0044] Zinc borate: ZB-503, Yishitong;

[0045] Hexaphenoxycyclotriphosphazene: HPCTP, Hongda Dante Chemical;

[0046] Phenoxy polyphosphazene: Hubei Darli Chemical Co., Ltd.;

[0047] Antimony White: S-05N, Changde Chenzhou Antimony Products Co., Ltd.

[0048] Aluminum diethylphosphinic acid: OP 1230, Clariant;

[0049] Toughening agent A-1: ​​maleic anhydride grafted SEBS, maleic anhydride grafting rate of 0.2wt%, self-made;

[0050] Toughening agent A-2: maleic anhydride grafted SEBS, maleic anhydride grafting rate of 0.4wt%, self-made;

[0051] Toughening agent A-3: maleic anhydride grafted SEBS, maleic anhydride grafting rate of 0.7wt%, self-made;

[0052] Toughening agent A-4: maleic anhydride grafted SEBS, maleic anhydride grafting rate 1wt%, self-made;

[0053] Toughening agent A-5: maleic anhydride grafted SEBS, maleic anhydride grafting rate 1.5wt%, self-made;

[0054] Toughening agent B: Maleic anhydride-grafted ethylene-octene copolymer, with a maleic anhydride grafting rate of 0.6 wt%, self-made;

[0055] The method for preparing the aforementioned maleic anhydride-grafted toughening agent is as follows: Ungrafted toughening agent, maleic anhydride, and initiator are subjected to a grafting reaction using a twin-screw extruder (screw temperature 150-180℃, length-to-diameter ratio 44:1). The initiator is selected from dicumyl peroxide, and the initiator addition amount is 0.5 wt% of the total feed. SEBS is purchased from Formosa Plastics' SEBS 6151; POE is purchased from Dow's POE ENGAGE 8137.

[0056] Toughening agent C: GMA grafted with POE; SOG-02, Jia Yi Rong;

[0057] Toughening agent D: SEBS, SEBS 6151, Formosa Plastics;

[0058] Toughening agent E: POE, POE ENGAGE 8137, DOW;

[0059] Antioxidant: Antioxidant 1010 and Antioxidant 168 are compounded in a weight ratio of 1:2.

[0060] Example and comparative PPE / PA alloy preparation method: According to the formula, the components are mixed evenly and granulated by extrusion through a twin-screw extruder with a screw speed of 400 rpm; the temperature of each section of the barrel is set to 230℃, 250℃, 260℃ and 270℃ to obtain a halogen-free flame-retardant PPE / PA alloy.

[0061] Test methods:

[0062] (1) Flame retardancy: Prepare a 1.5mm standard sample according to UL94-2022 standard and test the vertical burning rating of the material.

[0063] (2) Low temperature drop ball performance: According to the UL standard, the sample was injection molded into a square plate of 100*100*1.5mm. After adjusting at -35℃ for 3h, a steel ball with a diameter of 51mm and a weight of 535g was dropped at 1.295m to impact the plate. The square plate was observed to see if it cracked. If it cracked, it was NG; if it did not crack, it was OK.

[0064] (3) CTI: The CTI of the material is tested according to the CTI test standard of UL946A, and the material is rated according to the results (see the table below).

[0065] Tracking voltage (V) PLC TI≥600 0 400≤TI<600 1 250≤TI<400 2 175≤TI<250 3 100≤TI<175 4 0≤TI<100 5

[0066] (4) Precipitation assessment: The sample is injection molded into a square plate of 100*100*3.0mm and placed in PCT: 121℃, 2 atmospheres, 100% humidity for 196h to age. Observe whether the sample surface turns white. If it turns white, it means that precipitation is obvious and cannot meet the requirements.

[0067] (5) Dimensional stability: The material was injection molded into a square plate of 150*30*2mm. After testing its initial size, the change in length dimension was evaluated after 48 hours in a double 85 damp heat aging chamber.

[0068] Table 1: Distribution ratio (parts by weight) and test results of each component of PPE / PA alloy in Examples 1-8

[0069] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 PPE 40 32 20 17.8 15 25 15 25 PA66 40 48 60 62.2 45 75 PA612 45 PA6T / 66 75 Zinc borate 11 11 11 11 9 15 9 15 Toughening agent A-1 6 6 6 6 3 12 3 12 antioxidants 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 flame retardancy V-0 V-0 V-0 V-0 V-0 V-0 V-0 V-0 Low temperature ball drop performance OK OK OK OK OK OK OK OK CTI PLC 0 PLC 0 PLC 0 PLC 0 PLC 0 PLC 0 PLC 0 PLC 0 Precipitation No white hair No white hair No white hair No white hair No white hair No white hair No white hair No white hair Size change (%) 1.27 1.40 1.53 1.59 1.39 1.43 1.52 1.59

[0070] As can be seen from Examples 1-4 and Comparative Examples 1-2, the dimensional stability decreases as the nylon content increases; however, in Comparative Example 1, the low-temperature drop ball performance is poor and the CTI cannot meet the 0 level when the PPE content is too high; in Comparative Example 2, the dimensional stability is too poor when the nylon content is too high and the V-0 flame retardant rating cannot be achieved.

[0071] Table 2: Partial proportions (by weight) and test results of PPE / PA alloy components in Examples 9-14

[0072] Example 9 Example 10 Example 11 Example 12 Example 13 Example 14 PPE 32 32 32 32 32 32 PA66 48 48 48 48 48 48 Zinc borate 7.3 9.1 7.3 9.1 7.3 7.3 Hexaphenoxycyclotriphosphazene 3.7 1.9 3.7 Phenoxy polyphosphazene 3.7 antimony white 3.7 1.9 Toughening agent A-1 6 6 6 6 6 Toughening agent B 6 antioxidants 0.5 0.5 0.5 0.5 0.5 0.5 flame retardancy V-0 V-0 V-0 V-0 V-0 V-0 Low temperature ball drop performance OK OK OK OK OK OK CTI PLC 0 PLC 0 PLC 0 PLC 0 PLC 0 PLC 0 Precipitation No white hair No white hair No white hair No white hair No white hair No white hair Size change (%) 1.48 1.47 1.46 1.46 1.56 1.58

[0073] As can be seen from Examples 2 / 9-13, zinc borate is preferred as the flame retardant, resulting in better dimensional stability of the alloy.

[0074] As can be seen from Examples 9 / 13, phosphazenes exhibit better dimensional stability when selected from hexaphenoxycyclotriphosphazenes.

[0075] Table 3: Partial proportions (by weight) and test results of PPE / PA alloy components in Examples 15-17

[0076] Example 15 Example 16 Example 17 PPE 32 32 32 PA66 48 48 48 Zinc borate 11 11 11 Toughening agent A-2 6 Toughening agent A-3 6 Toughening agent A-4 6 antioxidants 0.5 0.5 0.5 flame retardancy V-0 V-0 V-0 Low temperature ball drop performance OK OK OK CTI PLC 0 PLC 0 PLC 0 Precipitation No white hair No white hair No white hair Size change (%) 1.28 1.31 1.46

[0077] As can be seen from Examples 2 / 15 / 16 / 17, when the maleic anhydride grafting rate of the preferred toughening agent is 0.4-0.7wt%, the dimensional change rate is lower.

[0078] Table 4: Partial proportions (by weight) and test results of each component of PPE / PA alloys in Comparative Examples 1-7

[0079] Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 PPE 48 16 32 32 32 32 32 PA66 32 64 48 48 48 48 18 Zinc borate 11 11 7.3 6 25 11 Aluminum diethylphosphite 11 3.7 Toughening agent A-1 6 6 6 6 6 6 1 antioxidants 0.5 0.5 0.5 0.5 0.5 0.5 0.5 flame retardancy V-0 V-2 V-1 V-0 V-1 V-0 V-0 Low temperature ball drop performance NG OK OK OK OK NG NG CTI PLC 1 PLC 0 PLC 0 PLC0 PLC 0 PLC 0 PLC 0 Precipitation No white hair No white hair white white No white hair No white hair No white hair Size change (%) 1.15 1.88 1.59 1.57 1.48 1.37 1.36

[0080] As can be seen from Comparative Example 3, the diethylaluminum hypophosphite flame retardant cannot achieve V-0 flame retardancy in the technical solution of this invention, and it is prone to precipitation.

[0081] As shown in Comparative Example 4, flame retardants formed when the ratio of zinc borate to aluminum diethylphosphite is not within a suitable range are prone to whitening and have a large dimensional change rate.

[0082] As can be seen from Comparative Example 5, if the flame retardant content of the present invention is insufficient, the flame retardant rating will not reach V-0.

[0083] As can be seen from Comparative Example 6, the low-temperature drop ball performance is poor when the flame retardant content of the present invention is too high.

[0084] As shown in Comparative Example 7, the low-temperature drop ball performance is poor when the toughening agent content is too low.

[0085] Table 5: Partial proportions (by weight) and test results of each component of the PPE / PA alloy in Comparative Examples 8-14

[0086] Comparative Example 8 Comparative Example 9 Comparative Example 10 Comparative Example 11 Comparative Example 12 Comparative Example 13 Comparative Example 14 PPE 32 32 32 32 32 32 32 PA66 48 48 48 48 48 48 48 Zinc borate 11 5.5 5.5 11 11 11 11 Hexaphenoxycyclotriphosphazene 5.5 antimony white 5.5 Toughening agent A-1 20 6 6 Toughening agent A-5 6 Toughening agent C 6 Toughening agent D 6 Toughening agent E 6 antioxidants 0.5 0.5 0.5 0.5 0.5 0.5 0.5 flame retardancy V-2 V-1 V-2 V-0 V-0 V-0 V-0 Low temperature ball drop performance OK OK OK NG NG NG NG CTI PLC 0 PLC 0 PLC 0 PLC 0 PLC 0 PLC 0 PLC 0 Precipitation No white hair No white hair No white hair No white hair No white hair No white hair No white hair Size change (%) 1.51 1.50 1.49 1.48 1.69 1.62 1.49

[0087] As shown in Comparative Example 7, the low-temperature drop ball performance is poor when the toughening agent content is too low.

[0088] As can be seen from Comparative Example 8, if the toughening agent content is too high, the flame retardancy will not reach V-0.

[0089] As can be seen from Comparative Examples 9-10, if zinc borate is compounded with other flame retardants, the content of zinc borate cannot be too low; otherwise, the flame retardancy will not reach V-0.

[0090] As can be seen from Comparative Examples 11-13, when GMA is used to graft SEBS, SEBS, and POE, the low-temperature drop ball performance is poor, especially when SEBS and POE are used, the dimensional change rate is high.

[0091] As shown in Comparative Example 14, when the maleic anhydride grafting rate in maleic anhydride-grafted SEBS is 1.5 wt%, the low-temperature drop ball performance is deteriorated.

Claims

1. A halogen-free flame-retardant PPE / PA alloy, characterized in that, By weight, it includes the following components: 60-100 parts of polyphenylene ether and polyamide; 9-15 parts of halogen-free flame retardant; 3-12 parts toughening agent; The halogen-free flame retardant is selected from at least one of zinc borate, zinc borate / phosphononitrile compound flame retardant, and zinc borate / antimony white compound flame retardant, wherein the weight ratio of zinc borate / phosphononitrile is (8-2):1, and the compounding ratio of zinc borate / antimony white is (8-2):

1. The weight ratio of polyphenylene ether to polyamide ranges from 1:(1-3.5). The toughening agent is selected from any one or more of maleic anhydride-grafted styrene block copolymers and maleic anhydride-grafted ethylene-octene copolymers, wherein the grafting rate of maleic anhydride is 0.4-0.7 wt%.

2. The halogen-free flame-retardant PPE / PA alloy according to claim 1, characterized in that, The polyphenylene ether is polymerized from 2,6-dimethylphenol or its derivatives.

3. The halogen-free flame-retardant PPE / PA alloy according to claim 1, characterized in that, The polyamide is selected from at least one of aliphatic polyamide and semi-aromatic polyamide.

4. The halogen-free flame-retardant PPE / PA alloy according to claim 1, characterized in that, The halogen-free flame retardant is selected from zinc borate.

5. The halogen-free flame-retardant PPE / PA alloy according to claim 1, characterized in that, The maleic anhydride-grafted styrene block copolymer is selected from at least one of maleic anhydride-grafted styrene-butadiene-styrene block copolymer, maleic anhydride-grafted styrene-ethylene / butene-styrene block copolymer, and maleic anhydride-grafted styrene-ethylene / propylene-styrene block copolymer.

6. The halogen-free flame-retardant PPE / PA alloy according to claim 1, characterized in that, Phosphazene is selected from at least one of hexaphenoxycyclotriphosphazene, phenoxypolyphosphazene, derivatives of hexaphenoxycyclotriphosphazene, and derivatives of phenoxypolyphosphazene.

7. The halogen-free flame-retardant PPE / PA alloy according to claim 6, characterized in that, Phosphazenes are selected from hexaphenoxycyclotriphosphazenes.

8. The halogen-free flame-retardant PPE / PA alloy according to claim 1, characterized in that, The product also includes 0.1-2 parts by weight of antioxidant, wherein the antioxidant is selected from at least one of phenolic antioxidants, phosphite antioxidants, or metal passivators.

9. The method for preparing the halogen-free flame-retardant PPE / PA alloy according to any one of claims 1-8, characterized in that, The process includes the following steps: mixing the components evenly according to the formula, granulating them by extrusion through a twin-screw extruder at a screw speed of 250-500 rpm and an extrusion temperature of 230-290℃ to obtain a halogen-free flame-retardant PPE / PA alloy.

10. The application of the halogen-free flame-retardant PPE / PA alloy according to any one of claims 1-8, characterized in that, Used in the manufacture of photovoltaic connectors.