A lightweight, high-strength, high-flow whisker polypropylene composite material and preparation method thereof

Abstract

The invention discloses a lightweight, high-strength, high-flow whisker polypropylene composite material and a preparation method thereof, comprising 92-99 parts by weight of polypropylene, 1-8 parts by weight of long alkane silane coupling agent modified whiskers, 0.1-0.4 parts by weight of antioxidants, 0.2-0.5 parts by weight of lubricants, and 0.1-0.3 parts by weight of anti-ultraviolet agents; the long alkane silane coupling agent modified whiskers are prepared by modifying basic magnesium sulfate whiskers with long alkane silane coupling agents; the long alkane silane coupling agent is an alkane silane coupling agent with the longest branch chain being C12 or more. The present invention starts from the interaction mechanism between composite interfaces, and utilizes the principle that long alkane coupling agents are grafted on the whisker surface and generate molecular entanglement with a plastic matrix during extrusion to prepare high-impact, high-rigidity whisker-polyolefin composite materials.

Description

Technical Field

[0001] The invention relates to the field of materials, and in particular to a lightweight, high-strength and high-fluidity whisker polypropylene composite material and a preparation method thereof. Background Art

[0002] Thin-walled high-rigidity plastic is a new type of plastic product with high strength and rigidity. Its main advantages are good fluidity, light weight, high rigidity, durability, corrosion resistance, easy manufacturing and processing, etc.

[0003] Thin-walled high-strength plastics have been widely used in the fields of industry, construction, medical treatment, aviation, automobiles, etc. For example, in automobile manufacturing, thin-walled high-strength plastics can be used to make lightweight automobile parts such as dashboards, door panels, seats, air-conditioning vents, etc. Due to its lightweight and excellent mechanical properties, the fuel consumption of automobiles can be reduced, the driving distance can be increased, and the carbon emissions of vehicles can also be reduced.

[0004] Whisker-filled plastic is a high-performance composite material that utilizes whisker reinforcement technology. Whiskers can be added to plastic to make it stronger and more rigid, and have better heat and wear resistance.

[0005] The advantages of whisker composites mainly include:

[0006] 1. High strength and high stiffness. By adding whiskers, the plastic can have higher strength and stiffness, allowing it to be used in applications that require high strength and high stiffness.

[0007] 2. Good heat resistance. Since whiskers have high thermal stability, adding whiskers can improve the heat resistance of plastics and enable long-term use in high temperature environments.

[0008] 3. Good wear resistance. Whisker-filled plastics have better wear resistance and can be used in applications that are often subject to wear, such as mechanical parts, car bodies, and ships.

[0009] 4. Lightweight. Although whisker-filled plastics have high strength and stiffness, they are still lighter than metals and other materials, so they can be used in applications where light weight is required.

[0010] In summary, whisker composites have great economic value and social significance as thin-walled high-rigidity materials.

[0011] In order to further improve the performance of whisker composite materials, patent CN114410274A uses one of silane coupling agents KH540, KH550, KH560, and KH570 to modify alumina whiskers, improve the compatibility of whiskers with composite materials, and improve the mechanical properties of composite materials; CN114957815A uses stearic acid to modify potassium titanate whiskers, basalt whiskers or anhydrous calcium carbonate whiskers to obtain composite materials with good mechanical properties. CN 102952336 B discloses an active basic magnesium sulfate whisker modified polypropylene composite material and a preparation method thereof, using one of silane coupling agents KH550, KH560, and KH570, or one of titanate NDZ-101 and NDZ-40 to modify whiskers, to obtain a whisker-polypropylene composite material with good tensile strength, bending strength, heat deformation temperature and flow properties.

[0012] However, the above methods for surface modification of whiskers all focus on improving the interface compatibility between whiskers and composite materials, which can achieve partial effects but are still not obvious. Summary of the invention

[0013] The technical problem to be solved by the present invention is to provide a lightweight, high-strength and high-fluidity whisker polypropylene composite material and a preparation method thereof in view of the deficiencies in the prior art.

[0014] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0015] A light, high-strength and high-fluidity whisker polypropylene composite material comprises 92-99 parts by weight of polypropylene, 1-8 parts by weight of long alkane silane coupling agent modified whiskers, 0.1-0.4 parts by weight of antioxidant, 0.2-0.5 parts by weight of lubricant and 0.1-0.3 parts by weight of anti-ultraviolet agent; the long alkane silane coupling agent modified whiskers are prepared by modifying basic magnesium sulfate whiskers with long alkane silane coupling agents; the long alkane silane coupling agents are alkane silane coupling agents with the longest branch chain being C12 or above.

[0016] In a further improvement, the long alkane silane coupling agent is dodecyltriethoxysilane or hexadecyltriethoxysilane.

[0017] In a further improvement, the antioxidant is a 1:1 mixture of antioxidant 1010 and antioxidant 168;

[0018] A further improvement is that the lubricant is an EBS type lubricant.

[0019] As a further improvement, the anti-ultraviolet agent is anti-ultraviolet agent 622.

[0020] A method for preparing a lightweight, high-strength, high-flow whisker polypropylene composite material comprises the following steps:

[0021] Step 1: Take a long alkane silane coupling agent, add methanol at a volume ratio of 1:1, and add 5%-10% deionized water by mass fraction of the coupling agent to perform a pre-hydrolysis treatment to obtain a hydrolyzed coupling agent;

[0022] Step 2: Put the basic magnesium sulfate whisker into a high-speed stirrer, stir at a low speed at a rate of 20 Hz, pour in the hydrolyzed coupling agent and mix, stir and heat to 110° C., keep for 5-10 minutes, cool down and stop the reaction, and obtain the long alkane silane coupling agent modified whisker; wherein the longest branched chain of the long alkane silane coupling agent is C12 or above; the mass of the long alkane silane coupling agent is 1% of the mass of the basic magnesium sulfate whisker;

[0023] Step 3, the main material and the auxiliary material are put into the main feeding port of the twin-screw extruder, and 1-8 parts by weight of the long alkane silane coupling agent modified whisker is put into the side feeding port, and extrusion molding is performed, and the extrusion temperature is 200°C in the front zone and 220°C in the rear zone to prepare a lightweight, high-strength and high-flow whisker polypropylene composite material; the main material is 92-99 parts by weight of polypropylene, and the auxiliary materials include 0.1-0.4 parts by weight of antioxidant, 0.2-0.5 parts by weight of lubricant, and 0.1-0.3 parts by weight of anti-ultraviolet agent.

[0024] As a further improvement, in the step 2, the mixture is stirred and heated to 110° C. and maintained for 5 minutes.

[0025] As a further improvement, the melt index of the polypropylene at 2.16 kg and 230° C. is ≥15 g / 10 min.

[0026] In a further improvement, the long alkane silane coupling agent is dodecyltriethoxysilane or hexadecyltriethoxysilane.

[0027] As a further improvement, the antioxidant is a 1:1 mixture of antioxidant 1010 and antioxidant 168; the lubricant is an EBS type lubricant; and the anti-ultraviolet agent is anti-ultraviolet agent 622.

[0028] Compared with the existing methods, the present invention has the following advantages:

[0029] In order to further improve the mechanical properties of whisker / polyolefin composite materials without reducing the fluidity of polyolefin, the present invention starts from the interaction mechanism between the interfaces of the composite materials and utilizes the principle that long alkane coupling agents are grafted on the surface of whiskers and then generate molecular entanglement with the plastic matrix during the extrusion process to prepare high-impact, high-rigidity whisker-polyolefin composite materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 IR spectra of different modification reagents;

[0031] Figure 2The whisker micromorphology under different high stirring conditions;

[0032] Figure 3 The whisker length diagram under different treatment conditions;

[0033] Figure 4 Schematic diagram of the entanglement of molecular chains produced at the interface of modified whiskers and polypropylene. DETAILED DESCRIPTION

[0034] The overall production steps of the present invention are as follows:

[0035] Take 1% of the whisker mass of long alkane silane coupling agent, add methanol at a volume ratio of 1:1, and add 10% deionized water by mass fraction of the coupling agent for pre-hydrolysis treatment; put the whiskers into a high-speed stirrer, stir at a low speed at a rate of 20 Hz, pour in the hydrolyzed coupling agent, then continue stirring and heat to 110°C, continue stirring, make the total stirring time 5 minutes, stop the reaction, and obtain modified whiskers.

[0036] The polypropylene and auxiliary materials are mixed in proportion, fed into the main feed port of the twin-screw extruder, and the modified whiskers are fed into the side feed port for extrusion molding. The extrusion temperature is 200°C in the front zone and 220°C in the rear zone to prepare the sample. The polypropylene is mixed with 85% PP-9030 and 15% PP3920.

[0037] The melt index of polypropylene is 15-30g / 10min (GB / T3682-2000);

[0038] The antioxidant is a 1:1 mixture of 1010 and 168;

[0039] The lubricant is EBS type lubricant;

[0040] The UV inhibitor is 622;

[0041] The extrusion conditions of the twin-screw extruder are as follows: temperature: 200-220° C., rotation speed: 20-60% of the rated rotation speed, and the rated rotation speed is 50 rpm.

[0042] The bending strength is tested according to the standard GB / T 9341-2008; the impact strength is tested according to GB / T 1043.1-2008; and the tensile strength is tested according to GB / T1040.1-2008.

[0043] The proportion range of each material in the twin-screw extruder is as follows:

[0044] raw material Content (phr) Polypropylene 92-99 Modified whiskers 1-8 Antioxidants 0.1-0.4 Lubricants 0.2-0.5 UV inhibitor 0.1-0.3

[0045] Comparative examples and embodiments are provided, and except for the following raw material ratios, the other raw materials and processes are the same: Comparative example:

[0046]

[0047] The product performance is shown in the following table:

[0048]

[0049]

[0050] Comparing samples 5, 6 and 1-4, it can be seen that when hexadecyltriethoxysilane and dodecyltriethoxysilane are used as modification agents, the tensile strength and flexural strength of the whisker composite material are not significantly improved, the composite material has a higher nominal strain at break and a higher impact strength, while the flexural modulus is greatly improved. In other words, hexadecyltriethoxysilane and dodecyltriethoxysilane can greatly improve the flexural modulus of the composite material while maintaining a higher toughness of the composite material, so that the composite material can meet the performance requirements of thin-walled high-rigidity materials.

[0051] By comparing samples 5 and 6, it can be seen that with the increase of the carbon chain, the flexural modulus, impact strength and other properties of the composite material are significantly improved, indicating that the long carbon chain silane coupling agent can improve the above two properties of the composite material.

[0052] By comparing samples 5, 7, and 8, it can be seen that with the increase in the content of hexadecyltriethoxysilane-modified whiskers, the modulus of the composite material is further improved, but the toughness is reduced. This is consistent with the general law of changes in the content and performance of reinforcing materials, and the content can be adjusted according to the actual product performance requirements.

[0053] As for properties such as fluidity and density, the long alkane silane coupling agent is not much different from other coupling agents as can be expected, so it was not tested.

[0054] Different coupling agents were coupled with basic magnesium sulfate whiskers and blank controls were set up. Figure 1 It can be seen that after modification, the whiskers are at 2917 and 2851 cm -1 Two small absorption peaks are generated, corresponding to the stretching vibration peaks of the methyl CH bond, indicating that the coupling agent is successfully grafted onto the whiskers.

[0055] The long alkane silane coupling agent and basic magnesium sulfate whiskers were microscopically observed under different high stirring conditions, such as Figure 2 As shown, the whisker lengths under different treatment conditions were measured. Figure 3 As shown, it can be seen that with the increase of stirring frequency and the extension of time, the whisker length gradually shortens (0 represents no data or poor data confidence, so it is discarded). Therefore, the best treatment condition is obtained based on experience, that is, low-speed stirring at 20 Hz for 5 minutes.

[0056] The principle of the present invention is that by selecting a long alkane coupling agent, the molecular chains can be entangled and bonded at the interface between the whisker and the polypropylene, which can greatly improve the flexural modulus, impact strength and other properties of the composite material. Figure 4 shown.

[0057] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A lightweight, high-strength, high-flow whisker polypropylene composite material, characterized in that: The invention comprises 92-99 parts by weight of polypropylene, 1-8 parts by weight of long alkane silane coupling agent modified whiskers, 0.1-0.4 parts by weight of antioxidant, 0.2-0.5 parts by weight of lubricant and 0.1-0.3 parts by weight of anti-ultraviolet agent; the long alkane silane coupling agent modified whiskers are prepared by modifying basic magnesium sulfate whiskers with long alkane silane coupling agent; the long alkane silane coupling agent is dodecyl triethoxy silane or hexadecyl triethoxy silane.

2. The lightweight, high-strength, high-flow whisker polypropylene composite material according to claim 1, characterized in that: The antioxidant is a mixture of antioxidant 1010 and antioxidant 168 in a ratio of 1:

1.

3. The lightweight, high-strength, high-flow whisker polypropylene composite material according to claim 1, characterized in that: The lubricant is an EBS type lubricant.

4. The lightweight, high-strength, high-flow whisker polypropylene composite material according to claim 1, characterized in that: The anti-ultraviolet agent is anti-ultraviolet agent 622.

5. A method for preparing a lightweight, high-strength, high-flow whisker polypropylene composite material, characterized in that: The steps include: Step 1: Take a long alkane silane coupling agent, add methanol at a volume ratio of 1:1, and add 5%-10% deionized water by mass fraction of the coupling agent to perform a pre-hydrolysis treatment to obtain a hydrolyzed coupling agent; Step 2: Put the basic magnesium sulfate whisker into a high-speed stirrer, stir at a low speed at a rate of 20 Hz, pour in the hydrolyzed coupling agent and mix, stir and heat to 110° C., keep for 5-10 minutes, cool down to stop the reaction, and obtain the long alkane silane coupling agent modified whisker; The long alkane silane coupling agent is dodecyl triethoxysilane or hexadecyl triethoxysilane; the mass of the long alkane silane coupling agent is 1% of the mass of the basic magnesium sulfate whisker; Step 3, the main material and the auxiliary material are put into the main feeding port of the twin-screw extruder, 1-8 parts by weight of the long alkane silane coupling agent modified whisker is put into the side feeding port, and extrusion molding is performed, the extrusion temperature is 200°C in the front zone and 220°C in the rear zone, and a lightweight, high-strength and high-flow whisker polypropylene composite material is prepared; the main material is 92-99 parts by weight of polypropylene, and the auxiliary materials include 0.1-0.4 parts by weight of antioxidant, 0.2-0.5 parts by weight of lubricant, and 0.1-0.3 parts by weight of anti-ultraviolet agent.

6. The method for preparing the lightweight, high-strength, high-flow whisker polypropylene composite material according to claim 5, characterized in that: In the step 2, the mixture is stirred and heated to 110° C. and maintained for 5 minutes.

7. The method for preparing the lightweight, high-strength, high-flow whisker polypropylene composite material according to claim 5, characterized in that: The melting index of the polypropylene at 2.16 kg and 230° C. is ≥15 g / 10 min.

8. The method for preparing the lightweight, high-strength, high-flow whisker polypropylene composite material according to claim 5, characterized in that: The antioxidant is a mixture of antioxidant 1010 and antioxidant 168 in a ratio of 1:1; the lubricant is an EBS lubricant; and the anti-ultraviolet agent is anti-ultraviolet agent 622.

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