A polyamide masterbatch, its preparation method and application

Abstract

The present invention discloses a polyamide masterbatch, which comprises the following components by weight: 40-60 parts of PA6 resin; 30-40 parts of a flame retardant; 10-20 parts of a PA6 / PA66 copolymer; and 2-6 parts of a benzenesulfonamide auxiliary. By compounding an appropriate amount of the PA6 / PA66 copolymer and the benzenesulfonamide auxiliary, the present invention can adjust the crystallization temperature of the polyamide to a lower range, and can significantly improve the fiber floating defect of the parts prepared by the LFT-D molding technology, and increase the thermal decomposition temperature and CTI.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and particularly relates to a polyamide masterbatch, a preparation method thereof, and an application thereof. Background Art

[0002] Compared with the two production processes of GMT (Glass-Mat Reinforce Thermoplastic) and LFT-G (Long-Fiber Reinforce Thermoplastic Granules) that rely on semi-finished sheets and pellets, the LFT-D forming technology (Long Fiber Reinforce Thermoplastic In Direct Processing) directly uses polymer masterbatch and glass fiber for production, eliminating the intermediate processes of plate making or granulation, and having advantages such as cost reduction and increased design freedom. In modern manufacturing, the LFT-D technology has widely replaced traditional materials such as steel, aluminum alloy, and SMC, and is applied to automotive and industrial fields such as automotive underbody shields, battery pack housings, building templates, and manure leakage plates.

[0003] With the rapid development of new energy vehicles, the types and forming technologies of modified plastics for automobiles are also constantly updated. Compared with traditional fuel vehicles, the main power source of new energy vehicles is the battery. The charging and discharging voltage of the power battery is as high as 600 - 800V, which is much higher than the 12V or 48V voltage of the start-stop battery of fuel vehicles. Therefore, the requirements for voltage resistance and fire resistance of new energy battery pack and surrounding connector materials are improved. Considering the weight reduction and efficiency increase of new energy vehicles, the fiber-reinforced thermoplastic composite material solution replacing the current aluminum alloy solution is the future development trend. However, the planar area of the power battery pack housing exceeds 1.5m 2 , and the weight reaches more than 10 kg. It is very difficult to produce with traditional injection molding technology, and it is generally believed in the industry that the LFT-D forming technology will become an ideal production method for battery pack housings.

[0004] The polymers suitable for LFT-D molding and applied to the housing of new energy battery packs and peripheral connecting equipment need to have the following advantages simultaneously: 1. Lower crystallization temperature; 2. Flame retardant UL94 V-0 rating; 3. CTI (Comparative Tracking Index) ≥ 600V; 4. High mechanical strength; 5. High temperature resistance (higher thermal decomposition temperature); 6. Good appearance after processing (less fiber floating), etc. The existing technologies mainly improve the above six requirements through the following methods respectively: 1. By selecting a resin matrix with a low crystallization temperature; 2. Adding a sufficient amount of flame retardant; 3. Selecting a flame retardant with a high CTI; 4. High mechanical strength can be improved by selecting high-strength and high-modulus glass fiber or other filling methods; 5. Selecting a high-temperature resistant flame retardant and a high-temperature polyamide resin; 6. Adding a surface modifier or modifying the glass fiber. However, it is still difficult to meet the above six requirements simultaneously. Summary of the Invention

[0005] The purpose of the present invention is to provide a polyamide masterbatch suitable for the LFT-D molding process.

[0006] The present invention is achieved through the following technical solutions:

[0007] A polyamide masterbatch, by weight, comprises the following components:

[0008] 40 - 60 parts of PA6 resin;

[0009] 10 - 20 parts of PA6 / PA66 copolymer;

[0010] 30 - 40 parts of flame retardant;

[0011] 2 - 6 parts of benzenesulfonamide auxiliaries;

[0012] The flame retardant is selected from a compound flame retardant of diethyl phosphinate and phosphite.

[0013] Preferably, the weight ratio of PA6 to PA66 in the PA6 / PA66 copolymer is (90~98):(2~10).

[0014] More preferably, the weight ratio of PA6 to PA66 in the PA6 / PA66 copolymer is (94~96):(4~6). A small amount of PA66 copolymerized in the PA6 molecular chain destroys the regularity of the PA6 molecular chain, reduces the crystallization ability and crystallization temperature of PA6, and can effectively improve the fiber floating problem of the composite material obtained by the LFT-D molding process.

[0015] The diethyl phosphinate is selected from at least one of aluminum diethyl phosphinate and zinc diethyl phosphinate; the phosphite is selected from at least one of aluminum phosphite and magnesium phosphite.

[0016] Preferably, the diethyl phosphinate accounts for 80-90 wt% of the flame retardant.

[0017] The benzene sulfonamide auxiliary agent is one of N-butyl benzene sulfonamide, N-ethyl o / p-toluene sulfonamide, p-carboxy benzene sulfonamide, and p-isopropyl toluene sulfonamide; preferably N-ethyl o / p-toluene sulfonamide.

[0018] The present invention has no particular limitation on the viscosity of the PA6 / PA66 copolymer. It is found through experiments that when the relative viscosity of the PA6 / PA66 copolymer is 2.2-2.7, the technical effects of the present invention can be achieved.

[0019] The present invention has no particular limitation on the viscosity of the PA6 resin. It is found through experiments that when the relative viscosity of the PA6 resin is 2.0-2.8, the object of the present invention can be achieved.

[0020] The above relative viscosity test standard is ISO 307-2019, and the test conditions are: 96% sulfuric acid solution, 25 °C

[0021] 0-2 parts of auxiliary agents can be selectively added according to actual needs, selected from antioxidants and lubricants.

[0022] The antioxidant can be N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionyl) hexanediamine, 4,4'-bis(α,α-dimethylbenzyl) diphenylamine; the lubricant can be ethylene acrylic acid copolymer, ethylene bis-fatty acid amide.

[0023] The preparation method of the polyamide masterbatch includes the following steps: according to the ratio, premix each component, and then extrude and pelletize through a twin-screw extruder at a temperature of 220-250 °C and a screw speed of 300-400 revolutions per minute to obtain the polyamide masterbatch.

[0024] The application of the polyamide masterbatch is used for manufacturing components by the LFT-D molding technology and the obtained components.

[0025] The present invention has the following beneficial effects:

[0026] By compounding an appropriate amount of PA6 / PA66 copolymer, benzenesulfonamide additives, and flame retardants in PA6 resin, the PA66 copolymer component and the benzenesulfonamide additives can disrupt the regularity of the PA6 molecular chain and increase the lubricity between molecular chains, thereby adjusting the crystallization temperature of the polyamide to a lower range. At the same time, it can significantly improve the fiber floating defect of the parts prepared by the LFT-D molding technology, increase the thermal decomposition temperature and CTI, so that the polyamide masterbatch of the present invention meets the requirements for CTI (greater than or equal to 600V), crystallization temperature (lower than 180°C), high heat resistance (thermal decomposition temperature greater than 380°C), and good appearance (less fiber floating and no whitening) for manufacturing components using the LFT-D molding technology. Detailed Embodiments

[0027] The present invention will be described in detail below with reference to specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that those of ordinary skill in the art can make several modifications and improvements without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0028] The sources of raw materials used in the examples and comparative examples are as follows:

[0029] PA6 resin A: The relative viscosity tested according to ISO 307-2019 standard is 2.5, purchased from Haiyang Chemical Fiber;

[0030] PA6 resin B: The relative viscosity tested according to ISO 307-2019 standard is 2.8, purchased from Haiyang Chemical Fiber;

[0031] PA6 / PA66 copolymer A: The relative viscosity tested according to ISO 307-2019 standard is 2.5 - 2.6, the weight ratio of PA6 to PA66 is 98:2, and the grade is PA6 J250166-1, provided by Juheshun;

[0032] PA6 / PA66 copolymer B: The relative viscosity tested according to ISO 307-2019 standard is 2.5 - 2.6, the weight ratio of PA6 to PA66 is 96:4, and the grade is PA6 J250166-2, provided by Juheshun;

[0033] PA6 / PA66 copolymer C: The relative viscosity tested according to ISO 307-2019 standard is 2.5 - 2.6, the weight ratio of PA6 to PA66 is 94:6, and the grade is PA6 J250166-3, provided by Juheshun;

[0034] PA6 / PA66 copolymer D: Relative viscosity of 2.5 - 2.6 tested according to ISO 307 - 2019 standard, weight ratio of PA6 to PA66 is 92:8, grade PA6 J250166 - 4, provided by Juheshun.

[0035] PA6 / PA66 copolymer E: Relative viscosity of 2.5 - 2.6 tested according to ISO 307 - 2019 standard, weight ratio of PA6 to PA66 is 90:10, grade PA6 J250166 - 5, provided by Juheshun.

[0036] PA66: PA66 EP - 158, relative viscosity of 2.8 tested according to ISO 307 - 2019 standard, purchased from Zhejiang Huafeng;

[0037] Aluminum diethylphosphinate: EXOLIT OP 1230, purchased from Clariant;

[0038] Aluminum phosphite: DN68, purchased from Zhuhai Wantong Special Engineering Plastics Co., Ltd.;

[0039] Magnesium phosphite: DN78, purchased from Zhuhai Wantong Special Engineering Plastics Co., Ltd.;

[0040] Other flame retardants: Exolit OP 1312, Exolit OP 1314, a compound of aluminum diethylphosphinate and melamine polyphosphate, purchased from Clariant.

[0041] N - butylbenzenesulfonamide: Purchased from Suzhou Jinzhong Chemical Co., Ltd.

[0042] N - ethyl - o - p - toluenesulfonamide: Purchased from Suzhou Jinzhong Chemical Co., Ltd.

[0043] p - carboxybenzenesulfonamide: Purchased from Suzhou Jinzhong Chemical Co., Ltd.

[0044] p - isopropylbenzenesulfonamide: Purchased from Suzhou Jinzhong Chemical Co., Ltd.

[0045] Antioxidant: N,N'-bis-(3-(3,5 - di - tert - butyl - 4 - hydroxyphenyl)propionyl)hexanediamine, antioxidant 1098, commercially available;

[0046] Lubricant: Ethylene - acrylic acid copolymer, commercially available;

[0047] Glass fiber: Commercially available.

[0048] Preparation method of polyamide masterbatch for examples and comparative examples: According to the ratio, premix each component, and then extrude and pelletize through a twin - screw extruder at a temperature of 220 - 250 °C and a screw speed of 300 - 400 revolutions per minute to obtain the polyamide masterbatch.

[0049] Testing methods:

[0050] (1) Crystallization temperature: Referring to the ISO 11357-1-2016 standard, the DSC method is used to test the crystallization temperature of the polyamide masterbatch to characterize the cooling rate of the material in the molten state.

[0051] (2) Thermal decomposition temperature: Referring to the ISO 11358-2-2021 standard, TG thermal analysis is used to test the thermal decomposition temperature of the polyamide masterbatch in an air atmosphere to characterize the thermal stability of the material during processing.

[0052] (3) LFT-D forming method: The polyamide masterbatch is added to the LFT-D equipment. At the same time, glass fiber (with an addition amount of 30 wt% of the total weight of the product) is added from the feeding port and a cake is obtained through extrusion. The target product is obtained through online molding. Taking a certain battery pack housing with a 30% glass fiber content as an example. The specific process parameters for each section are as follows: 1) Melting and blending stage: The first-order melting temperature is 270-280 °C, and the second-order mixing temperature is 280-290 °C; 2) Cake cutting stage: The cutting temperature is 280-300 °C; 3) Conveying stage: The heat preservation conveying temperature is 280-290 °C; Molding stage: The mold temperature is 130-150 °C, and the holding pressure time is 80 s.

[0053] Appearance of LFT-D products: Visually observe the surface of the LFT-D products to check for fiber floating and whitening caused by decomposition. The fiber floating grade is 0 for no fiber floating, 1 for slight fiber floating (less than or equal to 1-2 fiber floating points in an area of 20*20 mm, and the protruding fiber is small), 2 for obvious fiber floating (2-3 fiber floating points in an area of 20*20 mm, and the protruding fiber is larger), 3 for severe fiber floating (less than 5 fiber floating points in an area of 20*20 mm, and the protruding fiber is even larger); The whitening grade is 0 for no whitening, 1 for slight whitening, 2 for obvious whitening, and 3 for severe whitening.

[0054] CTI of LFT-D products: Cut a sample strip of 60 mm * 60 mm * 3.5 mm from the LFT-D products and test the CTI value of the sample strip referring to the IEC60112-2020 standard.

[0055] Table 1: Composition (parts by weight) and test results of polyamide masterbatches in Examples 1-7

[0056] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 PA6 Resin A 50 　 40 60 50 50 50 PA6 Resin B 　 50 　 　 　 　 　 PA6 / PA66 Copolymer A 15 15 10 20 15 15 15 Aluminum Diethylphosphinate 24 24 27 34 21 27 28.5 Aluminum Phosphite 6 　 3 6 9 3 1.5 Magnesium Phosphite 　 6 　 　 　 　 　 N-Butylbenzenesulfonamide 3 3 2 6 3 3 3 Antioxidant 0.2 Lubricant 0.3 Crystallization Temperature, °C 178 178.2 178.4 177.2 178.4 178.3 178.6 Thermal Decomposition Temperature, °C 391 390 390 386 385 392 388 Fiber Floating Grade 0 0 1 0 0 0 0 Whitening Grade 0 0 0 0 0 0 0 CTI, V 600 600 600 600 600 600 600

[0057] As can be seen from Examples 1-4, the technical solution of the present invention can achieve a CTI value of 600V and has the advantages of a low crystallization temperature, a high thermal decomposition temperature, and a good appearance.

[0058] As can be seen from Examples 1 / 5 / 6 / 7, at the preferred flame retardant ratio, the crystallization temperature is lower and the thermal decomposition temperature is higher.

[0059] Table 2: Composition (parts by weight) and test results of polyamide masterbatch in Examples 8 - 14

[0060] Example 8 Example 9 Example 10 Example 11 Example 12 Example 13 Example 14 PA6 Resin A 50 50 50 50 50 50 50 PA6 / PA66 Copolymer A 15 15 15 PA6 / PA66 Copolymer B 15 PA6 / PA66 Copolymer C 15 PA6 / PA66 Copolymer D 15 PA6 / PA66 Copolymer E 15 Aluminum Diethylphosphinate 24 24 24 24 24 24 24 Aluminum Phosphite 6 6 6 6 6 6 6 N-Butylbenzenesulfonamide 3 3 3 3 N-Ethyl-o,p-Toluenesulfonamide 3 p-Carboxybenzenesulfonamide 3 p-Isopropylbenzenesulfonamide 3 Crystallization Temperature, °C 178 177.9 177.7 177.4 178.1 178.2 178.4 Thermal Decomposition Temperature, °C 393 395 391 390 394 392 390 Fiber Floating Grade 0 0 1 1 0 0 0 Whitening Grade 0 0 0 0 0 0 0 CTI, V 600 600 600 600 600 600 600

[0061] As can be seen from Examples 1 / 8 - 11, the weight ratio of PA6 to PA66 in the PA6 / PA66 copolymer has a significant influence on the crystallization temperature, thermal decomposition temperature, and fiber floating.

[0062] As can be seen from Examples 1 / 12 - 14, the preferred N - ethyl - o - p - toluenesulfonamide has a higher thermal decomposition temperature.

[0063] Table 3: Composition (parts by weight) and test results of polyamide masterbatch in comparative examples

[0064] Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 PA6 Resin A 50 60 40 50 50 50 30 PA6 / PA66 Copolymer A 　 5 25 15 15 15 15 PA66 15 　 　 　 　 　 Exolit OP 1312 Exolit OP 1314 Aluminum Diethylphosphinate 24 24 24 24 24 24 40 Aluminum Phosphite 6 6 6 6 6 6 10 N-Butylbenzenesulfonamide 3 3 3 0 1 7 3 Crystallization Temperature, °C 176.9 178.6 176.4 182.7 180.4 177.5 177.2 Thermal Decomposition Temperature, °C 399 394 377 394 392 378 387 Fiber Floating Grade 3 2 0 3 2 0 3 Whitening Grade 0 0 0 0 0 1 0 CTI, V 600 600 600 600 600 550 600

[0065] As can be seen from Comparative Example 1, although the thermal decomposition temperature is higher when PA66 replaces the PA6 / PA66 copolymer, the fiber floating is severe and it cannot meet the requirements of LFT - D.

[0066] As can be seen from Comparative Examples 2 / 3, when the addition amount of the PA6 / PA66 copolymer is too low, it is insufficient to improve the fiber floating defect. When the addition amount of the PA6 / PA66 copolymer is too high, although the crystallization temperature is lower, the thermal decomposition temperature drops too much and it also cannot meet the requirements of LFT - D.

[0067] As can be seen from Comparative Examples 4 / 5, when N - butylbenzenesulfonamide is not added, the crystallization temperature is higher and the fiber floating is very poor; when the addition amount of N - butylbenzenesulfonamide is too low, the crystallization temperature is higher and the fiber floating reaches level 2, which cannot meet the requirements of LFT - D.

[0068] As can be seen from Comparative Example 6, when the addition amount of N - butylbenzenesulfonamide is too high, although the crystallization temperature drops to 177.5 °C, the thermal decomposition temperature also drops severely, the CTI also drops by 50 V, and the appearance of the molded part is prone to turning white, which cannot meet the requirements of LFT - D.

[0069] As can be seen from Comparative Example 7, if the content of the flame retardant is too high, the fiber floating is severe.

[0070] Continued Table 3

[0071] Comparative Example 8 Comparative Example 9 PA6 Resin A 50 50 PA6 / PA66 Copolymer A 15 15 PA66 Exolit OP 1312 30 Exolit OP 1314 30 Aluminum Diethylphosphinate Aluminum Phosphite N-Butylbenzenesulfonamide 3 3 Crystallization Temperature, °C 177.9 177.9 Thermal Decomposition Temperature, °C 382 381 Fiber Floating Grade 0 0 Whitening Grade 3 3 CTI, V 600 600

[0072] As can be seen from Comparative Examples 8 and 9, when using the flame retardants commonly used in the current LFT - D molding method, the whitening phenomenon is severe.

Claims

1. A polyamide masterbatch, characterized in that, By weight, it includes the following components: 40-60 parts of PA6 resin; 10-20 parts of PA6 / PA66 copolymer; 30-40 parts of flame retardant; 2-6 parts of benzenesulfonamide additives; The flame retardant is a composite flame retardant of diethylphosphinate and phosphite; The weight ratio of PA6 to PA66 in the PA6 / PA66 copolymer is (90-98): (2-10); The benzenesulfonamide auxiliary agent is one of N-butylbenzenesulfonamide, N-ethyl-o-toluenesulfonamide, p-carboxybenzenesulfonamide and p-isopropyltoluenesulfonamide.

2. The polyamide masterbatch according to claim 1, characterized in that The weight ratio of PA6 to PA66 in the PA6 / PA66 copolymer is (94-96): (4-6).

3. The polyamide masterbatch according to claim 2, characterized in that, The diethylphosphinate is selected from at least one of diethylphosphinate aluminum and diethylphosphinate zinc; the phosphite is selected from at least one of aluminum phosphite and magnesium phosphite.

4. The polyamide masterbatch according to claim 1, characterized in that, Diethylphosphinate accounts for 80-90 wt% of the flame retardant.

5. The polyamide masterbatch according to claim 1, characterized in that, The benzenesulfonamide auxiliary agent is N-ethyl o-p-toluenesulfonamide.

6. The polyamide masterbatch according to claim 1, characterized in that, The relative viscosity of the PA6 / PA66 copolymer is 2.2-2.7, the relative viscosity test standard is ISO 307-2019, and the test conditions are: 96% sulfuric acid solution, 25°C.

7. The polyamide masterbatch according to claim 1, characterized in that, The relative viscosity of the PA6 resin is 2.0-2.8, the relative viscosity test standard is ISO 307-2019, and the test conditions are: 96% sulfuric acid solution, 25°C.

8. The polyamide masterbatch according to claim 1, characterized in that, By weight, the invention also includes 0-2 parts of auxiliary agents, which are selected from at least one of antioxidants and lubricants.

9. The preparation method of the polyamide masterbatch according to any one of claims 1-8, characterized in that, The method comprises the following steps: premixing the components according to the proportion, extruding and granulating the components through a twin-screw extruder at a temperature of 220-250 DEG C and a screw speed of 300-400 rpm to obtain polyamide masterbatch.

10. Use of the polyamide masterbatch according to any one of claims 1-8, characterized in that, Used for manufacturing components using LFT-D forming technology.

11. A component, characterized in that, The polyamide masterbatch according to any one of claims 1 to 8 is manufactured by LFT-D molding technology.