PP / PA composite material and preparation method and application thereof

Abstract

The invention discloses a PP / PA composite material as well as a preparation method and application thereof. The PP / PA composite material comprises the following components in parts by weight: 50-80 parts of PA resin; 20 to 50 parts of PP resin; 10 to 30 parts of modified carbon fiber; wherein the relative viscosity of the PA resin is 2.38-2.8, and the melt flow rate of the PP resin under the conditions of 230 DEG C and 2.16 kg is 40-85 g / 10 min; the molar content of silicon on the surface of the modified carbon fiber is greater than or equal to 7%. According to the PP / PA composite material and the preparation method thereof, the modified carbon fibers with the surface silicon element content larger than or equal to 7% are added into a PP / PA system, the melt flow rate of PP resin and the relative viscosity of PA resin are adjusted, so that the system is easier to build a perfect network, and the prepared PP / PA composite material has good electromagnetic shielding effectiveness and meanwhile has good dry and wet mechanical properties.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of high polymer materials, and particularly relates to a PP / PA composite material and a preparation method and application thereof. BACKGROUND

[0002] Polyamide (PA) resin and polypropylene (PP) resin are two kinds of widely used high polymer materials. Among them, the PA resin has good mechanical properties, but its water absorption is large and the dimensional stability is poor; the PP resin has excellent water resistance, but its mechanical strength is low. The use of PP resin and PA resin together can combine the advantages of both and expand the application field.

[0003] However, the PA resin and the PP resin belong to a thermodynamically incompatible system, and the interfacial bonding force is weak when they are directly blended, resulting in poor comprehensive performance of the composite material. Carbon fibers have excellent properties such as high strength and high modulus, and adding them to the PP / PA system can improve the mechanical properties and make the composite material have certain electromagnetic shielding effect. However, due to the large inertness of the surface of the carbon fibers, the compatibility with the PA resin and the PP resin matrix is poor, which makes it more difficult to combine the PP / PA system. Usually, a compatibilizer (such as a silane coupling agent) is added to improve the compatibility, but the electromagnetic shielding effect of the prepared PP / PA composite material is limitedly improved. SUMMARY

[0004] The purpose of the present application is to overcome the defects or problems in the prior art that the electromagnetic shielding effect of the carbon fiber reinforced PP / PA composite material system is limitedly improved, and to provide a PP / PA composite material.

[0005] Another purpose of the present application is to provide a preparation method of the PP / PA composite material.

[0006] Another purpose of the present application is to provide an application of the PP / PA composite material.

[0007] To achieve the above-mentioned purposes, the present application adopts the following technical solutions: A PP / PA composite material comprises the following components calculated by weight parts: PA resin 50-80 parts; PP resin 20-50 parts; Modified carbon fiber 10-30 parts; The relative viscosity of the PA resin is 2.38-2.8, the melt flow rate of the PP resin under the condition of 230 DEG C and 2.16 kg is 40-85 g / 10 min; and the molar content of silicon element on the surface of the modified carbon fiber is greater than or equal to 7%.

[0008] This invention provides a PP / PA composite material, which uses PA resin and PP resin as matrix resins, and adds modified carbon fibers with a specific silicon content. Adjusting the relative viscosity of PA resin and the melt flow rate of PP resin can make it easier for the system and modified carbon fibers to form a complete network, so that the obtained PP / PA composite material has good electromagnetic shielding performance and high wet tensile strength retention.

[0009] It should be noted that the molar content of silicon on the surface of the modified carbon fiber described in this invention is ≥7%, for example, but not limited to ≥7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, 10.5%, 11%, 11.5%, 12%, 12.5%, 13%, 13.5%, 14%, 14.5%, 15%, 15.5%, or 16%, etc., as well as the specific values ​​between the above values. Due to space limitations and for the sake of brevity, the specific values ​​included in the range will not be exhaustively listed in this invention.

[0010] Furthermore, the molar content of silicon on the surface of the modified carbon fiber is 7.5-15%. With the increase of the molar content of silicon on the surface, the overall performance of the prepared PP / PA composite material first significantly improves and then decreases. This may be because as the silicon content on the surface of the modified carbon fiber increases, it is easier to form a complete network with the PA and PP resins of the specific system. However, when the silicon content further increases, self-polymerization and cross-linking will occur on the surface of the modified carbon fiber, forming a brittle layer, which leads to a decrease in the overall performance of the composite material.

[0011] Furthermore, the silicon molar content on the surface of the modified carbon fiber is 8-12%. PP / PA composite materials prepared within this range exhibit better overall performance.

[0012] Specifically, the molar content of silicon on the surface of the modified carbon fiber is the percentage of silicon content on the surface of the modified carbon fiber relative to the total molar number of all elements.

[0013] Furthermore, the molar content of silicon on the surface of the modified carbon fiber was determined by XPS analysis.

[0014] Specifically, an Al Kα excitation source (1486.6 eV) was used, and the vacuum level of the analysis chamber was <5×10⁻⁶. -8 Pa. With energy correction at C1s (284.8 eV), a narrow spectrum of Si2p (pass energy 20 eV) was acquired. The molar percentage of silicon was calculated by combining the peak area with the molar number of all elements and the sensitivity factor.

[0015] It should be noted that the relative viscosity of the PA resin described in this invention is 2.38~2.8, for example, but not limited to 2.38, 2.4, 2.42, 2.45, 2.48, 2.5, 2.52, 2.55, 2.58, 2.6, 2.62, 2.65, 2.68, 2.7, 2.72, 2.75, 2.78 or 2.8, etc., as well as the specific values ​​between the above points. Due to space limitations and for the sake of brevity, the specific values ​​included in the range will not be exhaustively listed in this invention.

[0016] Furthermore, the relative viscosity of the PA resin is 2.4~2.7. It should be noted that, in the PP / PA composite material of the present invention, the PA resin content is preferably not less than 35 wt%.

[0017] Furthermore, the test standard for the relative viscosity of the PA resin is GB / T12006.1-2009.

[0018] Furthermore, the PA resin includes PA6 and / or PA66.

[0019] Furthermore, the PA resin is PA66.

[0020] It should be noted that the melt flow rate of the PP resin described in this invention at 230℃ and 2.16kg is 40~85g / 10min, for example, but not limited to 40, 42, 45, 48, 50, 52, 55, 58, 60, 62, 65, 68, 70, 72, 75, 78, 80, 82 or 85g / 10min, and the specific values ​​between the above points are not exhaustively listed in this invention due to space limitations and for the sake of brevity.

[0021] Furthermore, the melt flow rate of the PP resin at 230°C and 2.16 kg is 50~80 g / 10 min.

[0022] Furthermore, the ratio of the melt flow rate of the PP resin to the relative viscosity of the PA resin at 230°C and 2.16 kg is (18.5~33.5):1. Within this range, the prepared PP / PA composite material exhibits superior overall performance.

[0023] Furthermore, the test standard for the melt flow rate of the PP resin is GB / T3682.1-2018.

[0024] Furthermore, the PP resin is an isotactic PP resin with an isotacticity > 95%.

[0025] Furthermore, the isotacticity of the PP resin was tested according to GB / T2412-2008.

[0026] Furthermore, the mass ratio of PA resin to PP resin is (0.9~5):1; preferably (1~4):1.

[0027] Furthermore, the modified carbon fiber has an average diameter of 5~8μm.

[0028] Furthermore, the length of the modified carbon fiber is 5-8 mm.

[0029] Specifically, the average diameter of the modified carbon fiber was obtained by scanning electron microscopy according to standard ASTM D3849-17.

[0030] Furthermore, the modified carbon fiber content in the PP / PA composite material is 12~23wt%.

[0031] The modified carbon fiber described in this invention can be either homemade or commercially available.

[0032] In some preferred embodiments, the modified carbon fiber can be prepared by the following method: Carbon fibers were oxidized by nitric acid to obtain oxidized carbon fibers; the oxidized carbon fibers were then modified in an ethanol solution of a silane coupling agent to obtain modified carbon fibers.

[0033] Specifically, the nitric acid is a 25-35 wt% nitric acid solution.

[0034] Specifically, the oxidation treatment temperature is 40~60℃.

[0035] Specifically, the oxidation treatment takes 2 to 4 hours.

[0036] Specifically, the carbon fiber is oxidized by nitric acid, then washed with water until neutral, and dried at 80-100°C for 12-24 hours to obtain oxidized carbon fiber.

[0037] Specifically, the ethanol solution of the silane coupling agent is an ethanol solution containing 0.5~3wt% silane coupling agent.

[0038] Specifically, the modification temperature is 40~60℃.

[0039] Specifically, the modification takes 1 to 3 hours.

[0040] Specifically, the oxidized carbon fiber is modified in an ethanol solution of a silane coupling agent and then dried at 80-100°C for 6-12 hours to obtain modified carbon fiber.

[0041] Specifically, the silane coupling agent includes γ-aminopropyltriethoxysilane and / or γ-glycidoxypropyltrimethoxysilane.

[0042] Preferably, the PP resin and modified carbon fiber components in the PP / PA composite material are introduced into the composite material in the form of masterbatch.

[0043] Furthermore, without affecting the electromagnetic shielding effect of the PP / PA composite material described in this invention, in order to improve the mechanical properties of the PP / PA composite material, 0.1 to 5 parts of toughening agent are also included.

[0044] Furthermore, the toughening agent includes POE elastomer.

[0045] Furthermore, without affecting the electromagnetic shielding effect and dry and wet mechanical properties of the PP / PA composite material described in this invention, it also includes 0.1 to 3 parts of processing aids.

[0046] Furthermore, the processing aids include, but are not limited to, antioxidants and / or lubricants.

[0047] Furthermore, the antioxidants include, but are not limited to, one or more of hindered phenolic antioxidants, phosphite antioxidants, or thioester antioxidants.

[0048] Specifically, the hindered phenolic antioxidants are N,N'-hexamethylene bis(3,5-di-tert-butyl-4-hydroxyphenylpropionamide) (Irganox 1098), pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (Irganox 1010), 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione (antioxidant 1790), 1,6-hexanediol bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (Irganox 259), and octadecyl β-(4-hydroxy-3,5-di-tert-butylphenyl)propionate (Irganox 1098). 1076) or one or more of 3,9-bis{2-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)acrylic acid]-1,1-dimethyl}-2,4,8,10-tetraoxaspirocycloundecane (ADK AO-80).

[0049] The phosphite antioxidant is one or more of tris(2,4-di-tert-butylphenyl) phosphite (antioxidant 168), bis(2,6-di-tert-butyl-4-tolyl) pentaerythritol phosphite (PEP-36), or 627A.

[0050] The thioester antioxidant is one or more of the following: distearate thiodipropionate, dodecyl thiodipropionate (antioxidant DLTDP), dilaurate thiodipropionate, or pentaerythritol-based dodecyl thiopropionate.

[0051] Furthermore, the lubricant includes, for example but not limited to, one or more of pentaerythritol stearate, silicone, oxidized polyethylene wax, PE wax, or PP wax.

[0052] This invention also protects a method for preparing the above-mentioned PP / PA composite material, comprising the following steps: The components are mixed in proportion, and then melt-extruded and granulated to obtain PP / PA composite material.

[0053] Furthermore, the preparation method includes the following steps: S1. Mix PP resin and modified carbon fiber in a certain proportion, melt extrude and granulate to obtain PP / carbon fiber masterbatch; S2. The PP / carbon fiber masterbatch described in step S1 is mixed with other components in proportion, and then melt-extruded and granulated to obtain the PP / PA composite material.

[0054] By first preparing PP / carbon fiber masterbatch, PP resin can be used as a continuous phase to coat the surface of modified carbon fiber, thus initially dispersing the modified carbon fiber and further improving its compatibility with PA resin in subsequent mixing.

[0055] Furthermore, the melt extrusion described in step S1 is performed using a twin-screw extruder.

[0056] Furthermore, the temperature of the twin-screw extruder in step S1 is 180~220℃.

[0057] Furthermore, the rotational speed of the twin-screw extruder described in step S1 is 200~400 rpm.

[0058] Furthermore, the melt extrusion described in step S2 is performed using a twin-screw extruder.

[0059] Furthermore, the temperature of the twin-screw extruder in step S2 is 250~280℃.

[0060] Furthermore, the rotational speed of the twin-screw extruder described in step S2 is 250~450 rpm.

[0061] This invention also protects the use of the above-mentioned PP / PA composite material in the preparation of materials for the aerospace and automotive fields. In particular, it protects the application of the PP / PA composite material in the preparation of parts possessing both good electromagnetic shielding effects and mechanical properties. Specifically, it protects the application of the PP / PA composite material in the preparation of materials such as automotive radar housings and / or drone housings.

[0062] A housing component is made of the aforementioned PP / PA composite material.

[0063] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a PP / PA composite material by adding modified carbon fibers with a silicon content of ≥7wt% to the PP / PA resin system and adjusting the melt flow rate of the PP resin and the relative viscosity of the PA resin to make the system easier to build a complete network. The resulting PP / PA composite material has good electromagnetic shielding performance and also has good dry and wet mechanical properties. Detailed Implementation

[0064] The present invention will be further described in detail below with reference to specific embodiments. These embodiments are only used to explain the present invention and are not intended to limit the scope of the present invention. Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods; the materials and reagents used are commercially available unless otherwise specified.

[0065] 1. Raw materials used in each embodiment and comparative example: PA resin: PA resin 1: PA66EP-158, relative viscosity 2.7, purchased from Zhejiang Huafeng; PA resin 2: PA66U3600NC01SS, relative viscosity 2.4, purchased from Invista; PA resin 3: PA66EP-122, relative viscosity 2.2, purchased from Zhejiang Huafeng; PA resin 4: PA66 T31, relative viscosity 3.1, purchased from Zhejiang Huafeng; PP resin: PP resin 1: Homopolymer PP, PPH-MN60 (BEIHAI), with a melt flow rate of 65 g / 10 min at 230℃ and 2.16 kg, purchased from Sinopec Beihai. PP resin 2: homopolymer PP, PPH9018, with a melt flow rate of 50 g / 10 min at 230℃ and 2.16 kg, purchased from Lanzhou Petrochemical; PP resin 3: homopolymer PP, PPH650R, with a melt flow rate of 80 g / 10 min at 230℃ and 2.16 kg, purchased from Zhejiang Hongji Petrochemical; PP resin 4: Copolymer PP, PP K9017, with a melt flow rate of 17 g / 10 min at 230℃ and 2.16 kg, purchased from Formosa Plastics, Taiwan. PP resin 5: Copolymer PP, PP BX3920, with a melt flow rate of 100 g / 10 min at 230℃ and 2.16 kg, purchased from SK Corporation, South Korea; Modified carbon fiber: Modified carbon fiber 1: Silicon molar content is 8%, self-made; Modified carbon fiber 2: Silicon molar content is 10%, self-made; Modified carbon fiber 3: Silicon molar content is 12%, self-made; Modified carbon fiber 4: Silicon molar content is 15%, self-made; Modified carbon fibers 1-4 are prepared by the following methods: Carbon fiber (SYT45S, average diameter 7μm, length 6mm, purchased from Zhongfu Shenying) was immersed in a 30wt% nitric acid solution and oxidized at 40-60℃ for 2-4 hours. After removal, it was washed with water until neutral and dried at 80-100℃ for 12-24 hours to obtain oxidized carbon fiber. The oxidized carbon fiber was then immersed in an ethanol solution containing 0.5-3wt% silane coupling agent (γ-aminopropyltriethoxysilane) and modified by soaking at 40-60℃ for 1-3 hours. After removal, it was dried at 80-100℃ for 6-12 hours to obtain modified carbon fiber. The silicon content on the surface of the modified carbon fiber was controlled by adjusting the concentration of the silane coupling agent and the soaking time. Modified carbon fiber 5: Silicon content is 10wt%, self-made; the preparation method is the same as modified carbon fiber 2, the only difference is that γ-(2,3-epoxypropoxy)propyltrimethoxysilane is used instead of γ-aminopropyltriethoxysilane. Silane coupling agents: γ-aminopropyltriethoxysilane (KH-550) was purchased from Nanjing Quanxi New Materials Co., Ltd. γ-(2,3-epoxypropoxy)propyltrimethoxysilane (KH-560) was purchased from Nanjing Shuguang Silane Chemical Co., Ltd. Antioxidant: A compound of antioxidant 1098 and antioxidant 608 in a 1:1 mass ratio, commercially available; Lubricant: Pentaerythritol stearate, commercially available; It should be noted that the parallel experiments in the examples and comparative examples all used raw materials from the same source.

[0066] 2. The polyolefin compositions in each embodiment and comparative example were prepared according to the formulations in Tables 1-2 and the following preparation methods: S1. PP resin and modified carbon fiber are mixed evenly in proportion, added to a twin-screw extruder, melt-extruded and granulated at 180~220℃ to obtain PP / carbon fiber masterbatch, wherein the rotation speed of the twin-screw extruder is 300 rpm; S2. The PP / carbon fiber masterbatch described in step S1 is mixed with other components in proportion and added to a twin-screw extruder. The mixture is then melt-extruded and granulated at 250~280℃ to obtain the PP / PA composite material. The rotation speed of the twin-screw extruder is 350 rpm.

[0067] The PP / PA composite material described in Example 12 was prepared by the following method: The components are mixed in proportion and added to a twin-screw extruder. The mixture is then melt-extruded and granulated at 250~280℃ to obtain a PP / PA composite material. The speed of the twin-screw extruder is 350 rpm.

[0068] 3. Performance Testing: (1) Dry and wet tensile modulus test: The modulus of the PP / PA composite materials prepared in each example and comparative example was determined according to the standard ISO-2-2016. The dry modulus was measured after the sample was dried at 80℃ for 24 hours, and the wet modulus was measured after the sample was placed in an environment of 60℃ and 72% humidity for 7 days. The wet tensile modulus retention rate was calculated according to the formula: wet tensile modulus retention rate (%) = wet modulus / dry modulus × 100%. The industry usually requires a wet tensile modulus retention rate of ≥80% for PA materials. (2) Electromagnetic shielding performance test: The PP / PA composite materials prepared in each embodiment and comparative example were injection molded into square plates of 150mm*150mm*2mm. The electromagnetic shielding effectiveness of the square plates in the frequency range of 0.3~3GHz (excluding 0.3GHz) was tested according to GB / T30142-2013, flange coaxial device test method.

[0069] Examples 1-13 and Comparative Examples 1-9 Table 1. Dosage (parts by weight) and properties of each component in PP / PA composites in Examples 1-13

[0070] Table 2. Amounts (parts by weight) and properties of each component in PP / PA composites in each comparative example.

[0071] As can be seen from Table 1, the PP / PA composite material prepared by the present invention has good electromagnetic shielding effectiveness and mechanical properties. Specifically, the electromagnetic shielding effectiveness is ≥25dB ​​and the wet tensile strength retention rate is ≥80%; preferably, the wet tensile strength retention rate is ≥85%.

[0072] As can be seen from Comparative Examples 1 and 2, if the amount of PA resin and PP resin used is not within the scope of this invention, the electromagnetic shielding effectiveness or wet tensile strength of the PP / PA composite material prepared cannot meet the requirements.

[0073] As can be seen from Comparative Examples 3 to 6, if the melt flow rate of the PP resin is too low or too high, or the relative viscosity of the PA resin is too low or too high, the system cannot be fully constructed into a complete network, and the electromagnetic shielding effectiveness of the PP / PA composite material decreases.

[0074] In Comparative Example 7, even with the addition of silane coupling agents, the electromagnetic shielding performance of the PP / PA composite material prepared using unmodified carbon fiber significantly decreased when unmodified carbon fiber was used.

[0075] As can be seen from Comparative Examples 8 and 9, if PA resin and PP resin outside the scope of this invention are used for compounding, the electromagnetic shielding performance of the resulting PP / PA composite material cannot meet the requirements.

[0076] 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 PP / PA composite material, characterized in that, Includes the following components, calculated in parts by weight: 50-80 parts of PA resin; 20-50 parts of PP resin; 10-30 parts of modified carbon fiber; The PA resin has a relative viscosity of 2.38~2.8, and the PP resin has a melt flow rate of 40~85g / 10min at 230℃ and 2.16kg. The modified carbon fiber has a silicon molar content of ≥7% on its surface.

2. The PP / PA composite material according to claim 1, characterized in that, The modified carbon fiber has an average diameter of 5~15μm.

3. The PP / PA composite material according to claim 1, characterized in that, The relative viscosity of the PA resin is 2.4~2.

7.

4. The PP / PA composite material according to claim 1, characterized in that, The melt flow rate of the PP resin at 230℃ and 2.16kg is 50~80g / 10min.

5. The PP / PA composite material according to claim 1, characterized in that, The silicon molar content on the surface of the modified carbon fiber is 7.5-15%; preferably, the silicon molar content on the surface of the modified carbon fiber is 8-12%.

6. The PP / PA composite material according to claim 1, characterized in that, The PP resin is isotactic PP resin with isotacticity > 95%.

7. The PP / PA composite material according to claim 1, characterized in that, Satisfy at least one of the following two conditions: (a) It also includes 0.1 to 5 parts of toughening agent; said toughening agent includes POE elastomer; (b) It also includes 0.1 to 3% processing aids; said processing aids include antioxidants and / or lubricants.

8. A method for preparing the PP / PA composite material according to any one of claims 1 to 7, characterized in that, Includes the following steps: The components are mixed in proportion, and then melt-extruded and granulated to obtain PP / PA composite material. Preferably, the preparation method includes the following steps: S1. Mix PP resin and modified carbon fiber in a certain proportion, melt extrude and granulate to obtain PP / carbon fiber masterbatch; S2. The PP / carbon fiber masterbatch described in step S1 is mixed with other components in proportion, and then melt-extruded and granulated to obtain the PP / PA composite material.

9. The application of the PP / PA composite material according to any one of claims 1 to 7 in the preparation of materials for the aerospace and automotive fields.

10. A housing component, characterized in that, It is prepared using the PP / PA composite material described in any one of claims 1 to 7.

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