Polypropylene composite material as well as preparation method and application thereof

Abstract

The invention relates to the technical field of general-purpose plastics, in particular to a polypropylene composite material as well as a preparation method and application thereof. The invention provides a polypropylene composite material. The polypropylene composite material is prepared from the following components in parts by weight: 52 to 78 parts of polypropylene resin, 17 to 38 parts of modified wollastonite fiber, 2.5 to 12 parts of polyethylene glycol containing maleimide groups and 0.1 to 1.5 parts of nucleating agent, wherein the surface of the modified wollastonite fiber contains amino groups. The polypropylene composite material has the advantages of high heat resistance, low creep characteristic and low floating fiber, and overcomes the defects of the existing polypropylene composite material in preparation of automobile structural parts.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of general-purpose plastics, in particular to a polypropylene composite material and a preparation method and application thereof. BACKGROUND

[0002] With the rapid development of new energy vehicles and intelligent driving technology, the automobile industry has put forward increasingly stringent requirements for the comprehensive performance of lightweight materials. Traditional metal structural parts (such as battery pack shells, engine peripheral parts, etc.) have been difficult to meet the core needs of electric vehicle (EV) range improvement and efficient thermal management due to their large weight and complex forming process. As a kind of lightweight, chemical corrosion resistant general-purpose plastic, polypropylene (PP) is widely used in automobile parts, but its performance short board is increasingly prominent in high-end scenarios: ordinary PP and glass fiber reinforced materials have poor heat resistance and are prone to creep deformation, which cannot meet the reliability requirements of key components such as high-voltage battery module supports and motor peripheral heat-resistant structural parts; in addition, the fiber-reinforced PP also has the problem of floating fibers, which affects its appearance.

[0003] In view of the above problems, the prior art has carried out many explorations, but there are still obvious limitations: Chinese application patent CN119823483A discloses a kind of high heat-resistant glass fiber reinforced polypropylene material, which has good heat resistance, but it does not pay attention to the problems of floating fiber and creep.

[0004] Therefore, it is urgent to develop new technologies to solve the problems of poor heat resistance, poor creep resistance and floating fibers of polypropylene composite materials to meet the application requirements of key structural parts of new energy vehicles. SUMMARY

[0005] The technical problem to be solved by the present application is to overcome the defects and deficiencies of the poor heat resistance, poor creep resistance and floating fiber of the polypropylene composite material in the prior art, and to provide a polypropylene composite material.

[0006] The purpose of the present application is to provide a preparation method of the above-mentioned polypropylene composite material.

[0007] Another purpose of the present application is to provide the application of the above-mentioned polypropylene composite material in the preparation of automobile structural parts.

[0008] The above-mentioned purposes of the present application are achieved by the following technical solutions: The present application protects a kind of polypropylene composite material, including the following weight parts of components: polypropylene resin 52~78 parts, modified wollastonite fiber 17~38 parts, polyethylene glycol containing maleimide group 2.5~12 parts, nucleating agent 0.1~1.5 parts; The surface of the modified wollastonite fiber contains amino groups.

[0009] The wollastonite fiber of the present application refers to a short-cut wollastonite fiber.

[0010] Compared with common short-cut fiber fillers such as glass fibers, the wollastonite fiber has better heat resistance and mechanical strength, and can theoretically endow the polypropylene composite material with better heat resistance and creep resistance. However, the wollastonite fiber has poor dispersibility in the polypropylene resin, and its direct addition cannot improve the heat resistance and creep resistance of the polypropylene composite material, and there is a significant floating fiber problem.

[0011] In the present application, the wollastonite fiber is modified to obtain a modified wollastonite fiber containing amino groups on the surface, and a polyethylene glycol containing a maleimide group is added to the polypropylene resin. During the melt extrusion process, the amino groups of the modified wollastonite fiber will undergo a Michael addition reaction with the maleimide groups in the polyethylene glycol containing a maleimide group, so that the polyethylene glycol segments are covalently linked to the surface of the wollastonite fiber. The polyethylene glycol segments linked to the surface make the modified wollastonite fiber have good dispersibility in the polypropylene composite material, and the modified wollastonite fiber is beneficial to arranging in the direction of the melt flow during processing and showing an ordered axial orientation. The axial orientation can optimize the stress transfer path, thereby significantly improving the creep resistance and heat resistance of the polypropylene material, and the floating fiber problem is also significantly improved. In addition, a nucleating agent is also added in the present application. The nucleating agent induces the polypropylene resin to form a crystalline polypropylene resin, which cooperates with the polyethylene glycol segments to further improve the performance of the polypropylene material.

[0012] In the present application, the amount of polypropylene resin can be specifically 52, 54, 55, 58, 60, 62, 65, 68, 70, 72, 75, 78 parts by weight or a range formed by any two of the above values. The amount of modified wollastonite fiber can be specifically 17, 19, 20, 23, 25, 28, 31, 33, 35, 38 parts by weight or a range formed by any two of the above values. The amount of polyethylene glycol containing a maleimide group can be specifically 2.5, 2.8, 3, 5, 7, 10, 11, 12 parts by weight or a range formed by any two of the above values. The amount of nucleating agent can be specifically 0.1, 0.3, 0.5, 0.6, 0.8, 1, 1.2, 1.5 parts by weight or a range formed by any two of the above values.

[0013] In the present application, the polypropylene resin is used as the main resin, and its content accounts for more than 50wt% of the polypropylene composite material.

[0014] Further, the polypropylene resin includes one or both of homopolymer polypropylene and copolymer polypropylene.

[0015] Further, the copolymer polypropylene is block copolymer polypropylene and / or random copolymer polypropylene.

[0016] Further, the polypropylene resin has a melt flow rate of 8-37 g / 10 min measured at 230 ℃ under a load of 2.16 kg according to ISO 1133-1:2022.

[0017] In the present application, the polypropylene resin has a melt flow rate of 8, 10, 13, 16, 18, 20, 22, 25, 27, 29, 31, 35, 37 g / mol or a range formed by any two of the above values measured at 230 ℃ under a load of 2.16 kg.

[0018] Further, the modified wollastonite fiber has an amino content of 0.005-0.06 wt% on the surface thereof.

[0019] In the present application, the modified wollastonite fiber has an amino content of 0.005 wt%, 0.01 wt%, 0.015 wt%, 0.025 wt%, 0.03 wt%, 0.045 wt%, 0.05 wt%, 0.055 wt%, 0.06 wt% or a range formed by any two of the above values on the surface thereof.

[0020] Preferably, the modified wollastonite fiber has an amino content of 0.015-0.055 wt% on the surface thereof.

[0021] The modified wollastonite fiber with the amino content is selected, and the polypropylene composite material obtained has better heat resistance and creep properties.

[0022] The amino content on the surface of the modified wollastonite fiber can be measured by XPS surface analysis.

[0023] Further, the wollastonite fiber in the modified wollastonite fiber has an average diameter of 4-6 μm in cross section and an average length of 55-95 μm.

[0024] In the present application, the average diameter and the average length of the wollastonite fiber in the modified wollastonite fiber are measured by a Leica microscope.

[0025] In the present application, the amino on the surface of the modified wollastonite fiber can be introduced by modification of a silane coupling agent. The modification of the silane coupling agent is in a conventional manner in the art, including dry treatment, wet treatment and vapor treatment, wherein the vapor treatment has a better effect.

[0026] Further, the preparation method of the wet treatment comprises the following steps: After the wollastonite fiber and the silane coupling agent containing amino are mixed and cured, the modified wollastonite fiber is obtained.

[0027] Further, the amino-containing silane coupling agent includes one or more of 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, and N-aminoethyl-3-aminopropyltrimethoxysilane.

[0028] Further, the mass ratio of the wollastonite fiber and the amino-containing silane coupling agent is 1: (0.005-0.02).

[0029] Preferably, the mixing condition is: temperature 90-110 ℃, time 20-60 min.

[0030] Further, the curing condition is: temperature 100-120 ℃, time 30-60 min.

[0031] Further, as a preferred mode, the wollastonite fiber can be first activated into a wollastonite fiber with silicon hydroxyl groups.

[0032] Further, the preparation method of the vapor treatment specifically includes the following steps: S1. Forming silicon hydroxyl groups on the surface of the wollastonite fiber to obtain an activated wollastonite fiber; S2. Contacting the activated wollastonite fiber obtained in step S1 with an amino-containing silane coupling agent vapor to occur hydrolysis condensation reaction, thereby obtaining the modified wollastonite fiber.

[0033] Further, in step S1, the method for forming silicon hydroxyl groups is oxygen plasma treatment.

[0034] Further, the oxygen plasma treatment condition is: power 250-350 W, vacuum degree 8-15 Pa, time 5-30 min.

[0035] Further, in step S2, the vapor contact condition is: temperature 110-130 ℃, carrier gas is nitrogen, carrier gas flow rate is 40-60 mL / min, and contact time is 20-45 min.

[0036] Further, the structure formula of the polyethylene glycol containing a maleimide group includes any one of the following: ; ; .

[0037] Further, the number average molecular weight of the polyethylene glycol containing a maleimide group is 500-11000 g / mol.

[0038] In the present application, the number average molecular weight of the polyethylene glycol containing maleimide group can be 500, 1000, 2000, 3000, 3500, 4500, 5000, 6000, 7000, 9000, 10000, 11000 g / mol or a range formed by any two of the above values. Preferably, the number average molecular weight of the polyethylene glycol containing maleimide group is 2000-10000 g / mol.

[0039] Further, the number average molecular weight of the polyethylene glycol containing maleimide group is tested by gel permeation chromatography (GPC).

[0040] The polyethylene glycol with the above molecular weight range is selected, and the heat resistance, fiber floating and creep performance of the obtained polypropylene composite material are better.

[0041] Preferably, the polyethylene glycol containing maleimide group accounts for 1wt%-20wt% of the polypropylene composite material.

[0042] In the present application, the polyethylene glycol containing maleimide group accounts for 1wt%, 3wt%, 5wt%, 6wt%, 8wt%, 9wt%, 10wt%, 15wt%, 20wt% of the polypropylene composite material or a range formed by any two of the above values.

[0043] Preferably, the polyethylene glycol containing maleimide group includes one or more of JKA3124, JKA5036 and JKA7018.

[0044] Further, the nucleating agent includes an alpha nucleating agent and / or a beta nucleating agent.

[0045] Preferably, the nucleating agent is a beta nucleating agent.

[0046] The beta nucleating agent is selected, and the heat resistance and fiber floating performance of the obtained polypropylene composite material are better.

[0047] Further, the alpha nucleating agent is one or both of sorbitol diacetal and aromatic phosphate.

[0048] Preferably, the sorbitol diacetal includes one or more of bis-1,3,2,4(4'-propylbenzyl)-1-propyl sorbitol, 1,3:2,4-di(3,4-dimethylbenzyl) sorbitol and 1,3:2,4-di(p-methylbenzyl) sorbitol.

[0049] Preferably, the aromatic phosphate includes one or more of sodium bis(4-tert-butylphenyl) phosphate, 2,2'-methylene-bis(4,6-di-tert-butylphenyl) aluminum phosphate and 2,2'-methylene-bis(4,6-di-tert-butylphenyl) ammonium phosphate.

[0050] Further, the beta nucleating agent is one or both of a rare earth nucleating agent, an amide nucleating agent.

[0051] Preferably, the rare earth nucleating agent includes one or more of lanthanum-stearic acid complex, cerium-stearic acid complex, neodymium-salicylic acid complex.

[0052] Preferably, the amide nucleating agent includes one or more of N,N'-dicyclohexyl-2,6-naphthalene dicarboxamide, N,N'-dicyclohexyl terephthalamide, N,N'-ethylene bis(12-hydroxystearamide).

[0053] Further, the polypropylene composite further includes the following components in parts by weight: 0-0.8 parts of other auxiliary agents.

[0054] In the present application, the amount of other auxiliary agents can be specifically 0, 0.2, 0.3, 0.5, 0.7, 0.8 parts by weight or a range formed by any two of the above values.

[0055] Further, the other auxiliary agent includes one or both of an antioxidant and a lubricant.

[0056] Generally, in the polypropylene composite, the amount of antioxidant is 0-0.3 parts, and the amount of lubricant is 0-0.5 parts.

[0057] Further, the lubricant includes at least one of ethylene bis-stearamide, erucamide, oleamide.

[0058] Further, the antioxidant includes one or more of hindered phenolic antioxidant, phosphite antioxidant, thioester antioxidant.

[0059] Further, the hindered phenolic antioxidant includes but is not limited to antioxidant SONOX 1010 and / or SONOX 1076.

[0060] Further, the phosphite antioxidant includes but is not limited to SONOX 168.

[0061] Further, the thioester antioxidant includes but is not limited to tripropyl dilauryl phosphite (DLTDP).

[0062] The present application protects the preparation method of the above-mentioned polypropylene composite, which includes the following steps: The components are weighed according to the formulation amount, mixed, melt extruded and granulated to obtain the polypropylene composite.

[0063] Further, the components are weighed according to the formula, the components except the modified wollastonite fiber are mixed, and then are fed from the main discharge port of the extruder, the modified wollastonite fiber is fed from the side feeding port of the extruder, and melt extrusion granulation is performed, so that the polypropylene composite material is obtained.

[0064] Further, the temperature of the extrusion granulation is 100-240 ℃, and the screw rotation speed of the extruder for the extrusion granulation is 300-500 rpm, and the screw length-diameter ratio is 36-48:1.

[0065] The application protects the application of the above-mentioned polypropylene composite material in the preparation of an automobile structural part.

[0066] Further, the automobile structural part includes a battery shell, a motor support or a vehicle-mounted radar support.

[0067] The application protects an automobile structural part prepared from the above-mentioned polypropylene composite material.

[0068] Compared with the prior art, the application has the following beneficial effects: The application provides a polypropylene composite material which has high heat resistance, low creep property and low floating fiber property. DETAILED DESCRIPTION

[0069] The application is further described below in combination with specific examples, but the examples do not limit the application in any form. Unless otherwise specified, the reagents, methods and equipment used in the application are conventional reagents, methods and equipment in the technical field.

[0070] Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0071] Polypropylene resin 1#: PPH-Y26, homopolymer PP, melt index is 26 g / 10 min (230 ℃, 2.16 kg), produced by Sinopec; Polypropylene resin 2#: PP HP500N, homopolymer PP, melt index is 11 g / 10 min (230 ℃, 2.16 kg), produced by Basell; Polypropylene resin 3#: PP EP548R, copolymer PP, melt index is 28 g / 10 min (230 ℃, 2.16 kg), produced by Sinopec-Shell; Wollastonite fiber A#: wollastonite fiber, average diameter of cross section is 5±0.5 μm, and average length is 80 μm, produced by Fengjiashan wollastonite fiber; Wollastonite fiber B#: wollastonite fiber, average diameter of cross section is 5±0.5 μm, and average length is 60 μm, produced by Fengjiashan wollastonite fiber; Modified wollastonite fiber 1#: self-made, process as follows: wollastonite fiber A# was placed in an oxygen plasma reactor (DT-03 type, power 300 W, vacuum degree 10 Pa), and the fiber surface was treated by plasma for 10 min to generate silanol groups; then 3-aminopropyltriethoxysilane (APTES, commercially available) vapor (120 °C, N2carrier gas flow rate 50 mL / min) was introduced, and the reaction was carried out for 30 min to form a monolayer, thereby obtaining modified wollastonite fiber 1#; the amino content in the surface of the modified wollastonite fiber 1# was 0.055wt% as measured by XPS surface analysis; Modified wollastonite fiber 2#: self-made, different from modified wollastonite fiber 1# in that the oxygen plasma treatment time was 5 min; the amino content in the surface of the modified wollastonite fiber 2# was 0.03wt% as measured by XPS surface analysis; Modified wollastonite fiber 3#: self-made, different from modified wollastonite fiber 1# in that wollastonite fiber A# was replaced by wollastonite fiber B#; the amino content in the surface of the modified wollastonite fiber 3# was 0.045wt% as measured by XPS surface analysis; Modified wollastonite fiber 4#: self-made, different from modified wollastonite fiber 1# in that 3-aminopropyltriethoxysilane was replaced by 3-aminopropyltrimethoxysilane; the amino content in the surface of the modified wollastonite fiber 4# was 0.05wt% as measured by XPS surface analysis; Modified wollastonite fiber 5#: self-made, process as follows: wollastonite fiber A# was added to a high-speed mixer, and stirring was started, and the temperature was raised to 90 °C, and preheating was carried out for 15 min; 3-aminopropyltriethoxysilane (APTES, commercially available) was diluted with an equal amount of anhydrous ethanol, and was slowly and uniformly added to the fiber, and the reaction was continued at 100 °C for 20 min, and then solidification was carried out in an oven at 120 °C for 40 min, thereby obtaining modified wollastonite fiber 5#; wherein the mass ratio of wollastonite fiber A# to 3-aminopropyltriethoxysilane was 1:0.01, and the amino content in the surface of the modified wollastonite fiber 1# was 0.015wt% as measured by XPS surface analysis; Monoamino polyethylene glycol A#: JKA5144, number average molecular weight 3500 g / mol, produced by Sigma-Aldrich; Maleimide group-containing polyethylene glycol 1#: JKA7018, number average molecular weight 10000 g / mol, produced by Sigma-Aldrich, and the structural formula is as shown below: ; Maleimide group-containing polyethylene glycol 2#: JKA5036, number average molecular weight 5000 g / mol, produced by Sigma-Aldrich, and the structural formula is as shown below: ; Polyethylene glycol 3 containing maleimide group: JKA3124, number average molecular weight 2000 g / mol, produced by Sigma-Aldrich, the structure is as follows: ; β nucleating agent 1: N,N'-dicyclohexyl-2,6-naphthalene dicarboxamide, produced by Shanxi Chemical Research Institute; β nucleating agent 2: lanthanum-stearic acid complex, WBG-II, produced by Guangdong Weilin; α nucleating agent: bis-1,3,2,4 (4'-propylbenzyl) -1-propyl sorbitol, produced by Milliken; Other auxiliary agent 1: lubricant: ethyl bis-stearamide EBS, commercially available; Other auxiliary agent 2: antioxidant: SONOX 1010, commercially available; Unless otherwise specified, each component (such as other auxiliary agent 1, other auxiliary agent 2) selected in each parallel example and comparative example is the same commercially available product.

[0072] The polypropylene composite material of each embodiment and comparative example of the present application is prepared by the following process: The components are weighed according to the formulation amount, mixed, and added to a twin-screw extruder for melt extrusion and granulation to obtain the polypropylene composite material. The temperature of the 1~12 zones of the twin-screw extruder is 100 ℃, 180 ℃, 200 ℃, 210 ℃, 220 ℃, 230 ℃, 230 ℃, 230 ℃, 230 ℃, 230 ℃, 230 ℃, 240 ℃, respectively, the screw rotation speed is 400 rpm, and the screw length-diameter ratio is 45:1.

[0073] Examples 1~13 Examples 1~13 provide a series of polypropylene composite materials, the weight fractions of each component in the formulation of which are shown in Table 1.

[0074] Table 1 Formulation of Examples 1~13

[0075] Comparative examples 1~4 Comparative examples 1~4 provide a series of polypropylene composite materials, the weight fractions of each component in the formulation of which are shown in Table 2. Table 2 Formulation of Comparative examples 1~4

[0076] Performance test of polypropylene composite material (1) Test method Thermal performance: heat distortion temperature (HDT) refers to standard ISO 75-2:2013.

[0077] Float: float test method refers to standard ISO 4287:1997; by measuring the arithmetic average deviation (Ra) of the profile of the surface of the composite injection sample plate, the larger the Ra value, the more severe the fluctuation of the surface profile, the more significant the unevenness, and the more serious the float effect (i.e. more float is exposed, and the surface is rougher).

[0078] Creep performance: tensile creep strain refers to standard ISO 899-1:2017.

[0079] Mechanical performance: flexural modulus refers to standard ISO 178:2019.

[0080] (2) Experimental results Table 3 Performance test results of each example and comparative example

[0081] As can be seen from Table 3, the polypropylene composite materials prepared in Examples 1-13 of the present application all have the characteristics of high heat resistance, low creep, high flexural modulus and low float. Specifically, the heat distortion temperature is ≥ 135 ℃, the tensile creep strain is ≤ 0.25%, the average deviation is ≤ 0.88 μm, and the flexural modulus is ≥ 4.6 GPa, and the comprehensive performance of Example 1 is the best.

[0082] Comparative Example 1, due to the absence of a nucleating agent, resulted in a decrease in heat resistance and severe float; Comparative Example 2, due to the replacement of modified wollastonite fibers with wollastonite fibers, resulted in a decrease in heat resistance and tensile creep performance, severe float, and poor rigidity; Comparative Example 3, due to the absence of polyethylene glycol containing a maleimide group, resulted in a decrease in heat resistance and tensile creep performance, severe float, and poor rigidity; Comparative Example 4, due to the replacement of polyethylene glycol containing a maleimide group with polyethylene glycol containing a single amino group, resulted in a decrease in heat resistance, severe float, a decrease in tensile creep strain, and poor rigidity.

[0083] The above examples are preferred embodiments of the present application, but the embodiments of the present application are not limited by the above examples, and any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the present application are equivalent replacement methods and are included in the protection scope of the present application.

Claims

1. A polypropylene composite, characterized in that, The polypropylene composite material comprises the following components in parts by weight: polypropylene resin 52-78 parts, modified wollastonite fiber 17-38 parts, polyethylene glycol containing maleimide group 2.5-12 parts, nucleating agent 0.1-1.5 parts. The surface of the modified wollastonite fiber contains amino groups.

2. The polypropylene composite of claim 1, wherein, The polypropylene resin has a melt flow rate of 8-37 g / 10 min at 230℃ under a load of 2.16 kg.

3. The polypropylene composite of claim 1, wherein, The amino group content in the surface of the modified wollastonite fiber is 0.005-0.06 wt%.

4. The polypropylene composite of claim 1, wherein, The wollastonite fiber in the modified wollastonite fiber has an average diameter of 4-6 μm and an average length of 55-95 μm.

5. The polypropylene composite of claim 1, wherein, The polyethylene glycol containing maleimide group has a number average molecular weight of 500-11000 g / mol.

6. The polypropylene composite of claim 1, wherein, The nucleating agent comprises an alpha nucleating agent and / or a beta nucleating agent.

7. The polypropylene composite of claim 1, wherein, The polypropylene composite material further comprises the following components in parts by weight: other auxiliary agent 0-0.8 parts.

8. Process for the production of the polypropylene composite material according to any one of claims 1 to 7, characterized in that, The method comprises the following steps: The components are weighed according to the formulation, mixed, melt-extruded and granulated to obtain the polypropylene composite material.

9. Use of the polypropylene composite material according to any one of claims 1-7 in the preparation of automobile structural parts.

10. An automotive structural member characterized by comprising: The polypropylene composite material is prepared from the polypropylene composite material according to any one of claims 1-7.

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