PA composite material as well as preparation method and application thereof

Abstract

The invention relates to a PA composite material as well as a preparation method and application thereof. The PA composite material comprises the following components: PA resin, a long-fiber filler, a flame retardant, a low-thermal-conductivity filler and an ablation-resistant filler. The PA composite material disclosed by the invention forms an ablation-resistant ceramic structure at a high temperature, can not be burnt through for a long time, has less deformation after ablation, and also has good heat insulation performance.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and more specifically, to a PA composite material, its preparation method, and its application. Background Technology

[0002] PA (polyamide) resin is a semi-crystalline polymer with good crystallinity, chemical stability, weather resistance and excellent mechanical properties. It is widely used in electronics, automobiles, new energy, photovoltaics and other fields.

[0003] In recent years, with the explosive growth of new energy vehicles, the requirements for the driving range of power batteries have become increasingly stringent, making lightweighting a development trend in new energy vehicles. The battery pack is a core component of the entire vehicle, playing a crucial role in supporting and protecting the power battery pack. Lightweighting the battery pack is one way to achieve vehicle lightweighting and improve driving range. Using composite materials with low-density engineering plastics such as PA resin as the base material and high-strength fibers as reinforcing fillers as the battery casing, replacing traditional metal materials to achieve lightweighting, can reduce the weight of the power battery casing by 20%-30%.

[0004] However, the fire resistance, ablation resistance, and deformation resistance of PA materials after thermal runaway in battery packs are important concerns for their application in the battery pack field. In particular, if PA materials do not burn through for a long time (more than 30 minutes) under high-temperature flame conditions and have small deformation, they can effectively prevent the fire from spreading to the entire vehicle, thereby avoiding a larger accident.

[0005] The patent with publication number CN119529519A provides a long fiber reinforced nylon material for battery packs that is resistant to ablation. It verifies that the material has good flame retardant properties, but this still cannot guarantee that the material will not be burned through for a long time under high temperature flame conditions.

[0006] The patent with publication number CN117866426A provides a ceramicizable burn-through resistant polyamide composite material. A 3mm thick sample of this material was burned through in 620s-730s in a spray gun test at 1500℃. It was burned through in a short time and does not take into account the deformation of the material before and after ablation.

[0007] In addition to the issues of burn-through and ablation deformation, the thermal insulation performance of the material also needs attention. In high-temperature environments, poor thermal insulation performance of the material can cause a rapid increase in the temperature of the passenger compartment, reducing the probability of occupant escape and threatening their lives. Summary of the Invention

[0008] The primary objective of this invention is to overcome the problems of short-term burn-through, large deformation before and after ablation, and the need to improve the thermal insulation performance of PA materials in the current technology, and to provide a PA composite material.

[0009] A further object of the present invention is to provide a method for preparing the above-mentioned PA composite material.

[0010] A further objective of this invention is to provide the application of the above-mentioned PA composite material in the preparation of electric vehicle battery components.

[0011] A further objective of this invention is to provide an electric vehicle battery component.

[0012] The above-mentioned objective of this invention is achieved through the following technical solution: A PA composite material comprises the following components in parts by weight: 35-61 parts of PA resin 11-51 parts of long fiber filler 1-20 parts flame retardant 1-15 parts of low thermal conductivity filler 0.5~15 parts of ablation-resistant filler; The thermal conductivity of the low thermal conductivity filler is ≤0.1 W / (K·m); The ablation-resistant filler is at least one of sepiolite, sepiolite and other inorganic fillers.

[0013] In this invention, the thermal conductivity of the low thermal conductivity filler can be measured at 23°C according to GB / T 13475-2008.

[0014] In this invention, the amount of PA resin used can be 35, 40, 45, 50, 55, 60 or 61 parts by weight; the amount of long fiber filler used can be 11, 15, 20, 25, 30, 35, 40, 45, 50 or 51 parts by weight; the amount of flame retardant used can be 1, 3, 5, 8, 10, 12, 15, 18 or 20 parts by weight; the amount of low thermal conductivity filler used can be 1, 3, 5, 8, 10, 12 or 15 parts by weight; and the amount of ablation resistant filler used can be 0.5, 1, 2, 3, 5, 8, 10, 12 or 15 parts by weight.

[0015] Preferably, the thermal conductivity of the low thermal conductivity filler is 0.01~0.1 W / (K·m), specifically 0.01, 0.02, 0.04, 0.06, 0.08 or 0.1 W / (K·m).

[0016] Preferably, the sepiolite is at least one of unmodified sepiolite, organically modified sepiolite, and sepiolite crystal inorganic material.

[0017] More preferably, the sepiolite is selected from organically modified sepiolite.

[0018] By using organically modified sepiolite, the resulting PA composite material exhibits smaller deformation and better thermal insulation performance.

[0019] Organically modified sepiolite can be siloxane-modified sepiolite, quaternary ammonium salt-modified sepiolite, metal ion-loaded sepiolite, etc.

[0020] Sepiolite is a synthetic inorganic compound, also known as artificial sepiolite.

[0021] Preferably, in the compound composed of sepiolite and other inorganic fillers, sepiolite accounts for 10 to 90 wt% of the compound by weight.

[0022] Preferably, the sepiolite has an average particle size of 1.5~100μm.

[0023] In this invention, the average particle size of sepiolite can be determined by laser diffraction.

[0024] Preferably, the other inorganic filler is at least one of kaolin, wollastonite, talc, mica, low-melting-point glass micro powder, or chopped fiber filler.

[0025] More preferably, when the other inorganic filler is a filler other than chopped fiber filler, the average particle size of the other inorganic filler is 0.5~500μm.

[0026] In this invention, the average particle size of other inorganic fillers can be determined by laser diffraction.

[0027] Preferably, the kaolin is selected from at least one of unmodified kaolin, calcined activated kaolin, and washed kaolin.

[0028] Preferably, the melting point of the low-melting-point glass powder is in the range of 320-850℃.

[0029] Preferably, the chopped fiber filler is at least one of chopped glass fiber, chopped carbon fiber, chopped ceramic fiber, or chopped mineral fiber.

[0030] Preferably, the length of the chopped fiber filler ranges from 1.5 to 7 mm, and the cross-sectional diameter ranges from 5 to 20 μm.

[0031] The length and cross-sectional diameter of the chopped fiber filler can be measured using an optical microscope.

[0032] In one embodiment, when the other inorganic fillers include chopped fiber fillers, the long fiber fillers in the PA composite material account for 53 to 100 wt% of the total weight of the fiber fillers.

[0033] Preferably, the long fiber filler is at least one of long glass fiber, long ceramic fiber, long carbon fiber, or long mineral fiber.

[0034] More preferably, the long fiber filler is at least one of long carbon fiber or long ceramic fiber.

[0035] By selecting at least one of long carbon fiber or long ceramic fiber, the resulting PA composite material exhibits smaller deformation after ablation.

[0036] More preferably, the long fiber filler is a long ceramic fiber.

[0037] By using long ceramic fibers, the resulting PA composite material exhibits smaller deformation and better thermal insulation performance.

[0038] More preferably, the long ceramic fiber is at least one of long oxide ceramic fiber or long non-oxide ceramic fiber.

[0039] More preferably, the long oxide-based ceramic fiber is at least one of long alumina fiber, long aluminosilicate fiber, long aluminoborosilicate fiber, long zirconium oxide fiber, or long yttrium oxide-alumina fiber.

[0040] More preferably, the long non-oxide ceramic fiber is at least one of long silicon carbide fiber, long boron fiber, or long boron nitride fiber.

[0041] Preferably, the cross-sectional diameter of the long fiber filler is in the range of 5~20μm.

[0042] The cross-sectional diameter of long fiber fillers can be measured using an optical microscope.

[0043] The type of flame retardant used in this invention is not particularly limited.

[0044] Preferably, the flame retardant is at least one of phosphorus-based flame retardants or halogen-based flame retardants.

[0045] More preferably, the flame retardant is a phosphorus-based flame retardant.

[0046] More preferably, the phosphorus-based flame retardant is at least one of hypophosphite flame retardant, phosphite flame retardant, and red phosphorus flame retardant.

[0047] Depending on the actual needs, flame retardants can be added in the form of masterbatch. The effective content of flame retardants in the masterbatch can be determined by conventional selection, such as 20~80wt% or 40~60wt%.

[0048] More preferably, the flame retardant is selected from red phosphorus flame retardants and hypophosphite flame retardants.

[0049] More preferably, the hypophosphite flame retardant is selected from at least one of aluminum dialkylphosphinate and aluminum hypophosphite; the phosphite flame retardant is selected from aluminum phosphite.

[0050] In one embodiment, the halogenated flame retardant is a brominated flame retardant.

[0051] Preferably, the low thermal conductivity filler is an inorganic filler, such as at least one selected from fumed silica, vermiculite, expanded perlite, diatomaceous earth, hollow glass microspheres, or pumice.

[0052] Preferably, the average particle size of the low thermal conductivity filler is 0.5~500μm.

[0053] In this invention, the average particle size of the low thermal conductivity filler can be determined by laser diffraction.

[0054] In this invention, PA resin is used as the matrix resin, and its content accounts for more than 23 wt% of the PA composite material.

[0055] Preferably, the mass percentage of long fiber filler in the PA composite material is 14~45wt%, more preferably 24~44wt%.

[0056] Preferably, the mass percentage of the low thermal conductivity filler in the PA composite material is 0.8~20wt%, more preferably 0.85~9wt%.

[0057] Preferably, the mass percentage of the ablation-resistant filler in the PA composite material is 0.4~20wt%, more preferably 0.4~11wt%.

[0058] Preferably, the PA resin is at least one of semi-aromatic PA resin and aliphatic PA resin.

[0059] More preferably, the semi-aromatic PA resin is selected from one or more of PA6T / 66, PA9T, PAMXD6, and PA6T / 6I; the aliphatic PA resin is selected from one or more of PA66, PA66 / 6 copolymer, PA6 / 66 copolymer, PA56, PA610, PA612, PA1010, PA1012, PA11, PA12, and PA6.

[0060] Preferably, the relative viscosity range of the PA resin is 1.5 to 4.5.

[0061] In this invention, the relative viscosity of the PA resin is tested according to GB / T 12006.1-2009, and the solvent is trifluoroacetic acid.

[0062] Preferably, the PA composite material further includes 0 to 3 parts of other additives.

[0063] Preferably, the other additives are at least one of antioxidants, lubricants, stabilizers, and colorants. The colorant may be carbon black or aniline black.

[0064] The aforementioned PA composite materials include long fiber filler masterbatch and composite PA resin masterbatch.

[0065] Preferably, the above-mentioned PA composite material is composed of long fiber filler masterbatch and composite PA resin masterbatch.

[0066] The long fiber filler masterbatch comprises the long fiber filler and 30-70 wt% of the PA resin; the composite PA resin masterbatch comprises the flame retardant, the low thermal conductivity filler, the ablation resistant filler, optional other additives, and 30-70 wt% of the PA resin.

[0067] Typically, the pellet length of the long fiber filler masterbatch ranges from 7 to 60 mm, for example, it can be selected as 10 to 15 mm.

[0068] Typically, the length range of the long fiber filler in the long fiber filler masterbatch is basically equal to the length range of the pellets of the long fiber filler masterbatch. Therefore, the length range of the long fiber filler in the long fiber filler masterbatch is 7~60mm, for example, 10~18mm (that is, the length range of the long fiber filler in the PA composite material is 7~60mm, for example, 10~18mm).

[0069] By measuring the length range of the long fiber filler in the PA composite material / long fiber filler masterbatch, it was further verified that the length range of the long fiber filler in the PA composite material / long fiber filler masterbatch is basically equal to the pellet length range of the long fiber filler masterbatch. The measurement method is as follows: the ash content of the PA composite material / long fiber filler masterbatch is obtained according to ISO 3451-1:2019, and then the long fiber filler is extracted from the ash and measured by optical microscopy.

[0070] The preparation method of the above-mentioned PA composite material includes the following steps: S1. Long fiber filler is impregnated with 30-70% PA resin melt, cooled, and pelletized to obtain long fiber filler masterbatch; the remaining 30-70% PA resin and the remaining components are mixed, melt-extruded, and granulated to obtain composite PA resin masterbatch; S2. Mix the long fiber filler masterbatch and the composite PA resin masterbatch to obtain the PA composite material.

[0071] The application of the aforementioned PA resin composite material in the preparation of electric vehicle battery components is also within the scope of protection of this invention.

[0072] An electric vehicle battery component is made from the aforementioned PA composite material.

[0073] Preferably, the electric vehicle battery component is a battery pack.

[0074] Compared with the prior art, the beneficial effects of the present invention are: When the PA composite material of this invention is ablated at high temperatures (e.g., 1500°C), sepiolite melts and binds low thermal conductivity fillers, long fiber fillers, flame retardants or their combustion residues, and other inorganic fillers (if any), forming Si-O-Si eutectics under high temperature, thus creating an ablation-resistant ceramic structure that can withstand burn-through for a long time. During combustion, water vapor and CO2 gases are generated, forming macroscopic pores as they escape. The dense carbon layer with microporous structure produced during the combustion of the flame retardant, along with the ceramic structure, provides thermal insulation. The low thermal conductivity fillers dispersed within the ceramic structure further reduce the thermal conductivity of the ablation-resistant layer, enhancing the insulation effect. Furthermore, the low thermal conductivity fillers reduce heat transfer, further lowering the temperature of the part itself, thus minimizing deformation during ablation. In addition, the addition of long fiber fillers significantly improves the flexural strength of the PA composite material. Detailed Implementation

[0075] To more clearly and completely describe the technical solution of the present invention, the present invention will be further described in detail below through specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention. Various changes can be made within the scope of the claims of the present invention.

[0076] The reagents used in the various embodiments and comparative examples of this invention are described below: PA Resin 1#: PA66, EPR27, Pingdingshan Shenma Engineering Plastics Co., Ltd.; PA resin #2: PA6, HY-2500A, Haiyang Chemical Fiber; PA resin 3#: PA66 / 6, EP26CL, Huafeng Chemical Co., Ltd.; PA resin 4#: PA9T, GC71010, Jiangsu Boyun Plastics Co., Ltd.; Long fiber filler #1: Long glass fiber, ER4301H-2400, continuous fiber, Chongqing International; Long fiber filler #2: Long carbon fiber, SYP 24K, continuous fiber, Jilin Carbon Valley Carbon Fiber Co., Ltd.; Long fiber filler #3: Long ceramic fiber, Nextel-312, continuous fiber, 3M; Flame retardant 1#: Red phosphorus flame retardant, red phosphorus masterbatch FR9950KF, red phosphorus content 50%, Tongcheng Xinde New Materials Co., Ltd. (In Tables 1-3 below, when the flame retardant used is flame retardant 1#, its dosage refers to the weight parts converted to pure red phosphorus). Flame retardant #2: Aluminum diethylphosphinic acid, OP 1230, Clariant; Low thermal conductivity filler #1: Vermiculite, 800 mesh, Lingshou County Huajing Mica Co., Ltd., with a thermal conductivity of 0.08 W / (K·m); Low thermal conductivity filler #2: Fumed silica, HL-300, Hubei Huifu Nanomaterials Co., Ltd., with a thermal conductivity of 0.02 W / (K·m); Low thermal conductivity filler #3: Nano-kaolin, Hydrite TS 90, Imerys, with a thermal conductivity of 0.17 W / (K·m); Sepiolite 1#: Unmodified sepiolite: 200 mesh sepiolite, Nanyang City Wolong District Leibao Sepiolite Processing Co., Ltd.; Sepiolite 2#: Organically modified sepiolite, Addins Clay Fireproof 80T, Tolsa; Sepiolite 3#: Organically modified sepiolite, Addins Clay 80T, Tolsa; Other filler #1: Unmodified kaolin, EP CLAY A108, EPChem; Other filler #2: Short-cut glass fiber, E7CS10-03-568H, average length 3mm, Jushi Group; Other filler #3: Wollastonite, HQ-1250, Dalian Global Minerals Co., Ltd.; Other filler #4: Low melting point glass powder, melting point 530℃, G57D, Foshan Taoyiseyou Co., Ltd. Other filler #5: Calcium silicate, Nordkalk C7 from Finland; Other additives #1: Aniline black masterbatch: N54 / 1033, from British company, Golley; Other additives #2: Antioxidant: RIANOX1098, Rianon.

[0077] Unless otherwise specified, all components used in the parallel examples and comparative examples (e.g., other additives 1#, other additives 2#) are the same commercially available products.

[0078] The PA composite materials of the embodiments and comparative examples of the present invention were prepared by the following preparation method: Preparation method of PA composite material in the examples and comparative examples: Step A: PA resin is extruded through a twin-screw extruder (temperature of each zone is 180~320℃, screw length-to-diameter ratio is 64:1, screw speed is 300 rpm) to obtain melt, and then passed through an impregnation die connected to the extruder die head. At the same time, long fiber filler passes through the impregnation die, and after cooling, drawing and pelletizing, long fiber filler masterbatch is obtained; the pellet length of the long fiber filler masterbatch is 15 mm, and correspondingly, the length of the long fiber filler in the long fiber filler masterbatch is... Step B: The mass of PA resin in the 15mm long fiber filler masterbatch is 60% of the mass of PA resin in the final PA composite material; Step C: According to the formula, the remaining 40wt% PA resin and the remaining components are mixed evenly, and granulated by extrusion through a twin-screw extruder (temperature of each zone is 180~310℃, screw length-to-diameter ratio is 64:1, screw speed is 300 rpm) to obtain composite PA resin masterbatch; Step C: The composite PA resin masterbatch is then mixed with the long fiber filler masterbatch to obtain PA composite material.

[0079] The performance of the PA composite materials provided in the embodiments and comparative examples of this invention was determined according to the following test methods: (1) Ablation resistance test: A 100mm×100mm square plate with a thickness of 2mm was prepared by injection molding. The square plate was placed horizontally, and a spray gun with a flame temperature of about 1500℃ was used to ablate the square plate in the center, directly below, and perpendicular to the plane of the square plate. The ablation was continued for 60 minutes or until it was burned through. The time of burning through was recorded. For the square plate that was not burned through, the deformation before and after ablation was tested: the ablated square plate was placed on a water platform, and the distance L (mm) from the highest point of the square plate to the water platform was measured. The deformation (mm) = L-2.

[0080] (2) Thermal insulation performance: A square plate with a thickness of 2mm×100mm×100mm was injection molded. The plate was placed horizontally, and a spray gun with a flame temperature of approximately 1500℃ was used to ablate it directly below the plate (for 60 minutes). During the ablation process, a thermocouple sensor connected to a computer was placed in the center of the unablated side of the plate to test and automatically record the temperature of the back side during the ablation process. The temperature-time curve of the back side temperature versus the ablation time was obtained, and the highest temperature of the back side during the ablation process was recorded. If the plate was burned through within 60 minutes, the temperature of the back plate would jump to nearly 1500℃ within 10 seconds after the burn-through. In this case, the highest temperature of the back side before the temperature jump was recorded. The higher the highest temperature of the back side, the worse the thermal insulation performance, and vice versa.

[0081] (3) Bending strength test: The test was conducted in accordance with ISO 178:2019 standard, with a tensile speed of 2 mm / min.

[0082] Examples 1-15 Examples 1-15 provide a series of PA composite materials, the formulations of which are shown in Tables 1-2.

[0083] Table 1. Formulations (parts by weight) of the Examples .

[0084] Table 2 Formulations (parts by weight) of the Examples .

[0085] Comparative Examples 1-9 Comparative Examples 1-9 provide a series of PA composite materials, the formulations of which are shown in Table 3.

[0086] Table 3 Formulations (parts by weight) for Comparative Examples 1-9 .

[0087] The properties of the PA composite materials in each embodiment and comparative example were determined according to the test methods mentioned above, and the test results are shown in Table 4.

[0088] Table 4. Performance test results of PA composite materials in each example and comparative example. .

[0089] As can be seen from Table 4: The PA composite materials in Examples 1-15 were not burned through in the ablation resistance test, and the deformation after ablation was ≤1.6mm, the highest temperature on the back side was ≤278℃, and the flexural strength was ≥200MPa. This shows that the PA composite material of the present invention is resistant to burn-through, has small deformation after ablation, good thermal insulation performance, and good flexural strength.

[0090] In Comparative Example 1, the PA composite material was reinforced with short-cut fiber filler instead of long-fiber filler. The PA composite material burned through quickly, exhibiting poor thermal insulation and flexural strength. In Comparative Example 2, the PA composite material was reinforced with an equal amount of long-fiber filler instead of sepiolite. The PA composite material burned through quickly, exhibiting poor thermal insulation and flexural strength. In Comparative Examples 4-7, the PA composite materials were reinforced with other fillers instead of sepiolite. The PA composite materials burned through quickly, exhibiting poor thermal insulation. In Comparative Example 8, no low-thermal-conductivity filler was added; in Comparative Example 9, the low-thermal-conductivity filler was not added, and its thermal conductivity was not controlled within a suitable range. The resulting PA composite materials not only exhibited poor thermal insulation but also large deformation after ablation.

[0091] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A PA composite material, characterized in that, The components include the following parts by weight: 35-61 parts of PA resin 11-51 parts of long fiber filler 1-20 parts flame retardant 1-15 parts of low thermal conductivity filler 0.5~15 parts of ablation-resistant filler; The thermal conductivity of the low thermal conductivity filler is ≤0.1 W / (K·m); The ablation-resistant filler is at least one of sepiolite, sepiolite and other inorganic fillers.

2. The PA composite material according to claim 1, characterized in that, The long fiber filler is at least one of long glass fiber, long ceramic fiber, long carbon fiber, or long mineral fiber.

3. The PA composite material according to claim 1, characterized in that, The flame retardant is at least one of phosphorus-based or halogen-based flame retardants.

4. The PA composite material according to claim 1, characterized in that, The low thermal conductivity filler is at least one of fumed silica, vermiculite, expanded perlite, diatomaceous earth, hollow glass microspheres, or pumice.

5. The PA composite material according to claim 1, characterized in that, The other inorganic fillers are at least one of kaolin, wollastonite, talc, mica, low-melting-point glass micro powder, or chopped fiber fillers.

6. The PA composite material according to claim 1, characterized in that, The PA resin is at least one of semi-aromatic PA resin and aliphatic PA resin.

7. The PA composite material according to claim 1, characterized in that, The PA composite material also includes 0 to 3 parts of other additives.

8. The method for preparing the PA composite material according to any one of claims 1 to 7, characterized in that, Includes the following steps: S1. Long fiber filler is impregnated with 30-70% PA resin melt, cooled, and pelletized to obtain long fiber filler masterbatch; the remaining 30-70% PA resin and the remaining components are mixed, melt-extruded, and granulated to obtain composite PA resin masterbatch; S2. Mix the long fiber filler masterbatch and the composite PA resin masterbatch to obtain the PA composite material.

9. The application of the PA composite material according to any one of claims 1 to 7 in the preparation of electric vehicle battery components.

10. A battery component for an electric vehicle, characterized in that, It is prepared from the PA composite material described in any one of claims 1 to 7.