Polypropylene metal composite material as well as preparation method and application thereof

Abstract

The invention relates to a polypropylene metal composite material as well as a preparation method and application thereof, and belongs to the technical field of compositions of high-molecular compounds. The polypropylene metal composite material comprises the following components in parts by weight: 20-40 parts of polypropylene, 10-40 parts of metal powder, 2-5 parts of a compatilizer, 25-30 parts of a flame retardant and 10-20 parts of glass fibers, the metal powder is a metal elementary substance and / or a metal oxide of which the retention particle size D50 is less than or equal to 20 microns, and the retention length of the glass fiber is 0.5-2 mm. The polypropylene metal composite material not only has good mechanical property and melt flowability, but also has excellent flame retardant property.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer compound compositions, and particularly relates to a polypropylene metal composite material, a preparation method thereof, and an application thereof. Background Art

[0002] Compared with plastics, metal polymer composite materials have both metal functionality and polymer advantages. They are an important means to realize the lightweight of metal materials and the functionalization of polymer materials, and play a crucial role in scientific and technological fields such as the automotive industry, aerospace, and consumer electronics. However, metal polymer composite materials are generally composed of polymer resins and metal sheets or metal fibers, and are difficult to be applied to injection molding manufacturing, and cannot be injection molded into automotive or electric bicycle accessories with relatively complex structures. Moreover, polypropylene, which is often used in parts such as automotive instrument panels, battery pack housings, seat protectors, and bumpers, has a very low limiting oxygen index (about 18%) due to its own nature, resulting in poor flame retardancy of polypropylene metal composite materials. In addition, the poor compatibility between polypropylene and metal will also lead to poor mechanical properties of polypropylene metal composite materials. Therefore, it is necessary to develop a polypropylene metal composite material with high melt fluidity, high flame retardancy, and good mechanical properties. Summary of the Invention

[0003] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a polypropylene metal composite material, a preparation method thereof, and an application thereof.

[0004] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0005] In the first aspect, the present invention provides a polypropylene metal composite material, which comprises the following components in parts by weight: 20-40 parts of polypropylene, 10-40 parts of metal powder, 2-5 parts of compatibilizer, 25-30 parts of flame retardant, and 10-20 parts of glass fiber;

[0006] The retained particle size D of the metal powder 50 is a metal element or metal oxide with ≤ 20 μm, and the retained length of the glass fiber is 0.5-2 mm.

[0007] The present invention promotes the uniform dispersion of metal powder and glass fiber by regulating the particle size of the metal powder and the retention length of the glass fiber in the polypropylene metal composite, and uses metal powder with a suitable particle size to reduce the orientation of the glass fiber, so that the glass fiber forms an interpenetrating structure, thereby improving the mechanical properties of the polypropylene metal composite to a certain extent; at the same time, the metal powder dispersed between the glass fibers has good thermal conductivity, and can accelerate the melting of the glass fiber to form a skeleton when heated, and interact with the flame retardant to form a flame retardant and ablation-resistant system, thereby significantly improving the flame retardant grade of the polypropylene metal composite and achieving a good smoke suppression effect. In addition, it is found that too large a particle size of the metal powder will lead to obvious orientation in the polypropylene metal composite, and then the parts are prone to warping; too long a retention length of the glass fiber will also exacerbate warping to a certain extent, and too short a retention length of the glass fiber will lead to poor mechanical properties of the composite material.

[0008] The polypropylene in the above polypropylene metal composite is the matrix resin, and its mass percentage content ≥ 15%; the morphology of the metal powder is spherical, quasi-spherical or rod-shaped, and its mass percentage content in the polypropylene metal composite is 9% - 45%; optionally, the retained particle size D of the above metal powder 50 Specifically, it can be 20μm, 18μm, 16μm, 14μm, 12μm, 10μm, 8μm, 6μm, 4μm, 2μm.

[0009] The retained particle size D of the metal powder 50 refers to the particle size D of the metal powder in the polypropylene metal composite obtained by melt extrusion of each component 50 , and can be measured by the following method: Burn off the resin of the material at 650°C, and then use a particle size analyzer (model MasterSizer 2000) for testing.

[0010] The retention length of the glass fiber refers to the actual length of the glass fiber in the polypropylene metal composite obtained by melt extrusion of each component, and can be measured by the following method: Burn off the resin of the material at 650°C, and then observe the retention length of the glass fiber under a two-dimensional image for the remaining glass fiber powder.

[0011] Optionally, the weight parts of polypropylene in the above polypropylene metal composite can specifically be 22 parts, 24 parts, 26 parts, 28 parts, 30 parts, 32 parts, 34 parts, 36 parts, 38 parts; the weight parts of the metal powder can specifically be 15 parts, 20 parts, 25 parts, 30 parts, 35 parts; the weight parts of the compatibilizer can specifically be 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts; the weight parts of the flame retardant can specifically be 26 parts, 27 parts, 28 parts, 29 parts; the weight parts of the glass fiber can specifically be 11 parts, 13 parts, 15 parts, 17 parts, 19 parts.

[0012] As a preferred embodiment of the polypropylene metal composite material of the present invention, among the components of the polypropylene metal composite material, the polypropylene is 25 to 35 parts by weight, the metal powder is 20 to 30 parts by weight, and the glass fiber is 13 to 17 parts by weight.

[0013] As a preferred embodiment of the polypropylene metal composite material of the present invention, the retained particle size D of the metal powder 50 is 13 to 19 μm; preferably, the impurity content in the metal powder is less than 0.1%.

[0014] As a preferred embodiment of the polypropylene metal composite material of the present invention, the material of the metal powder is at least one of aluminum and its oxides, iron and its oxides, and steel. The surface of the metal powder may or may not be modified; the modification includes organic modification, etc.

[0015] As a preferred embodiment of the polypropylene metal composite material of the present invention, the polypropylene adopts the ISO1133-2022 standard, and the melt mass flow rate under the conditions of 230 °C and 2.16 kg is ≥ 20 g / 10 min. Optionally, the melt mass flow rate of the polypropylene may specifically be 20 g / 10 min, 22 g / 10 min, 24 g / 10 min, 26 g / 10 min, 28 g / 10 min, 30 g / 10 min, 35 g / 10 min.

[0016] As a preferred embodiment of the polypropylene metal composite material of the present invention, the polypropylene adopts the ISO1133-2022 standard, and the melt mass flow rate under the conditions of 230 °C and 2.16 kg is 25 to 30 g / 10 min.

[0017] As a preferred embodiment of the polypropylene metal composite material of the present invention, the polypropylene metal composite material satisfies at least one of the following conditions:

[0018] a. The polypropylene is block copolymerized polypropylene, or a mixture of block copolymerized polypropylene and homopolypropylene; when the polypropylene contains block copolymerized polypropylene, it is more conducive to the uniform dispersion of the metal powder and the improvement of the toughness of the composite material.

[0019] b. The compatibilizer includes polyolefin graft maleic anhydride polymers; preferably, the polyolefin graft maleic anhydride polymers are polypropylene graft maleic anhydride or ethylene-octene copolymer graft maleic anhydride.

[0020] c. The flame retardant is a halogen-free flame retardant; preferably, the halogen-free flame retardant includes at least one of melamine polyphosphate and piperazine pyrophosphate; more preferably, the halogen-free flame retardant is a mixture of melamine polyphosphate and piperazine pyrophosphate, and the mass ratio of melamine polyphosphate to piperazine pyrophosphate is 1:(1-3).

[0021] d. The diameter of the glass fiber is 10-15 μm.

[0022] As a preferred embodiment of the polypropylene metal composite material of the present invention, in the components of the polypropylene metal composite material, 0.2-1 part by weight of a processing aid is further included; the processing aid includes at least one of an antioxidant, a lubricant, and a color powder.

[0023] In a second aspect, the present invention provides a method for preparing the above polypropylene metal composite material, including the following steps: mixing each component evenly and melt-extruding to obtain the polypropylene metal composite material. Optionally, a twin-screw extruder can be used for melt-extrusion, the temperature of melt-extrusion is 180-230 °C, and the screw speed of the twin-screw extruder is 500-600 revolutions per minute.

[0024] In a third aspect, the present invention provides the application of the above polypropylene metal composite material in the preparation of parts of an automobile or an electric bicycle. For example, the parts of the electric bicycle can specifically be a pedal, a storage box, a seat bucket, etc.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] The present invention promotes the uniform dispersion of metal powder and glass fiber by regulating the particle size of the metal powder and the retention length of the glass fiber in the polypropylene metal composite material, and uses the metal powder with a suitable particle size to reduce the orientation of the glass fiber, so that the glass fiber forms an interpenetrating structure, thereby improving the mechanical properties of the polypropylene metal composite material to a certain extent; at the same time, the metal powder dispersed between the glass fibers has good thermal conductivity, and can accelerate the melting of the glass fiber to form a skeleton when heated, and interact with the flame retardant to form a flame-retardant and ablation-resistant system, thereby significantly improving the flame retardant grade of the polypropylene metal composite material and achieving a good smoke suppression effect. In addition, the polypropylene metal composite material of the present invention also has good melt fluidity, and can be applied to injection molding to prepare parts with complex structures to meet the needs of different application scenarios. Specific Embodiments

[0027] To better illustrate the purpose, technical solution and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0028] Other materials, reagents, etc. used in the examples and comparative examples can be obtained from commercial channels without special instructions.

[0029] 1. Raw materials and reagents

[0030] 1) Polypropylene

[0031] Polypropylene 1 (block copolymerized polypropylene), with a melt mass flow rate of 26 g / 10 min, grade PP EP548R, manufactured by CNOOC and Shell;

[0032] Polypropylene 2 (composed of block copolymerized polypropylene and homopolypropylene in a mass ratio of 1:1), with a melt mass flow rate of 28 g / 10 min; among which, the block copolymerized polypropylene has a grade of PP K9930(H) and is manufactured by Yanshan Petrochemical, and the homopolypropylene has a grade of PP-KFZ30S and is manufactured by Kingfa Science & Technology.

[0033] 2) Metal powder

[0034] Metal powder 1 is secondary reduced iron powder, with a particle size D 50 of 19 μm, manufactured by Laizhou Aoxing Powder;

[0035] Metal powder 2 is ferrite powder, with a particle size D 50 of 15 μm, manufactured by Laizhou Aoxing Powder;

[0036] Metal powder 3 is steel powder, with a particle size D 50 of 15 μm, manufactured by Zhongye Xindun Alloy;

[0037] Metal powder 4 is secondary reduced iron powder, with a particle size D 50 of 75 μm, manufactured by Shandong Luyin.

[0038] 3) Compatibilizer

[0039] Compatibilizer 1 (polypropylene grafted maleic anhydride), grade PP-3, manufactured by Ningbo Nengzhiguang;

[0040] Compatibilizer 2 (ethylene-octene copolymer grafted maleic anhydride), grade POE-G, manufactured by Ningbo Nengzhiguang.

[0041] 4) Flame retardant

[0042] Flame retardant 1 is a halogen-free intumescent flame retardant (composed of melamine polyphosphate and piperazine pyrophosphate in a mass ratio of 1:2), grade JLS-260, manufactured by Hangzhou Jierisi;

[0043] Flame retardant 2 is a halogen-free flame retardant (composed of melamine polyphosphate and piperazine pyrophosphate in a mass ratio of 1:2.5), grade FP-2200, manufactured by ADK STAB.

[0044] 5) Glass fiber

[0045] Glass fiber 1, with a diameter of 13 μm, a length of 2 mm, grade 508AKF, and manufacturer Jushi Glass Fiber;

[0046] Glass fiber 2, with a diameter of 13 μm, a length of 3 mm, grade CSPP, and manufacturer Chongqing International Glass Fiber.

[0047] 6) Processing aids

[0048] The lubricant is N,N'-ethylenebisstearamide (EBS), commercially available;

[0049] The antioxidant is compounded from RIANOX 1010 (commercially available) and RIANOX 168 (commercially available) at a mass ratio of 1:2.

[0050] 2. Examples 1 - 9 and Comparative Examples 1 - 6

[0051] Table 1 Weight parts of each component of the polypropylene - metal composite material in the examples

[0052]

[0053]

[0054] The preparation method of the polypropylene - metal composite material in Example 1 includes the following steps:

[0055] According to the formula, polypropylene, metal powder, compatibilizer, flame retardant, glass fiber, lubricant, and antioxidant are mixed and then added to a twin - screw extruder for melt extrusion to obtain the polypropylene - metal composite material; among them, the temperatures of each zone of the twin - screw extruder are: zone 1 at 190 °C, zone 2 at 195 °C, zone 3 at 195 °C, zone 4 at 195 °C, zone 5 at 200 °C, zone 6 at 200 °C, zone 7 at 200 °C, zone 8 at 200 °C; the length - diameter ratio of the screw is 42:1, and the rotational speed of the screw is 550 revolutions per minute.

[0056] The preparation methods of the polypropylene - metal composite materials in Examples 2 - 4, Example 9, Comparative Example 1, and Comparative Examples 4 - 6 are the same as that in Example 1.

[0057] The preparation methods of the polypropylene - metal composite materials in Examples 5 - 8 and Comparative Examples 2 - 3 are basically the same as that in Example 1. By adjusting the combination of the screw blocks, the shear strength of the twin - screw extruder is increased to reduce the retention length of the glass fiber, and the shear strength of the twin - screw extruder is reduced to increase the retention length of the glass fiber.

[0058] Table 2 Weight parts of each component of the polypropylene - metal composite material in the comparative examples

[0059]

[0060] 3. Performance testing

[0061] 1) Melt index: Measured according to Standard GB / T 3682-2000, at a temperature of 230 °C and a load of 2.16 kg;

[0062] 2) Izod notched impact strength (23 °C): Measured according to Standard GB / T 1843-2020, with notch type A;

[0063] 3) Flexural modulus: Measured according to Standard GB / T 9341-2008, with the specimen being an injection molded bar with a length of 80 mm, a width of 10 mm, and a thickness of 4 mm;

[0064] 4) Flame retardant rating: According to the UL94 standard, a 2-mm-thick injection molded bar was taken for vertical burning test.

[0065] Table 3 Properties of polypropylene metal composites in each example and comparative example

[0066]

[0067] According to the data in Table 3, it can be seen that the melt mass flow rate (melt index) of the polypropylene metal composites in Examples 1 to 9 is ≥ 8 g / 10 min, and at the same time, the Izod notched impact strength (23 °C) is ≥ 5.5 KJ / m 2 、the flexural modulus is ≥ 2800 MPa, and the flame retardant rating reaches V-0 level, indicating that the polypropylene metal composites of the present invention not only have good mechanical properties and melt fluidity, but also have excellent flame retardant properties. It can be seen from Comparative Example 1 that when the particle size D 50 of the metal powder is too large, it will significantly reduce the mechanical properties and flame retardant rating of the polypropylene metal composite; it can be found from Comparative Examples 2 and 3 that when the retained length of the glass fiber is too short, it is easy to cause a decrease in the Izod notched impact strength, flexural modulus, and flame retardant properties of the polypropylene metal composite; when the retained length of the glass fiber is too long, it is easy to cause a decrease in the melt fluidity of the polypropylene metal composite and a reduction in the Izod notched impact strength and flame retardant properties. It can be seen from Comparative Example 4 that when there is too much metal powder in the polypropylene metal composite, it will cause a decrease in both melt fluidity and mechanical properties. At the same time, due to the excessive metal powder promoting the decomposition of the flame retardant during the melt extrusion process and destroying the heat insulation layer formed by the flame retardant during combustion, the flame retardant properties of the polypropylene metal composite are significantly reduced. It can be found from Comparative Examples 5 and 6 that when the polypropylene metal composite does not contain a flame retardant, it will cause a significant decrease in the melt fluidity, mechanical properties, and flame retardant properties of the polypropylene metal composite; while when the polypropylene metal composite does not contain metal powder, although it can maintain good flame retardant properties, it will significantly reduce its melt fluidity and flexural modulus.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A polypropylene metal composite material, characterized in that, By weight parts, it comprises the following components: 20 - 40 parts of polypropylene, 10 - 40 parts of metal powder, 2 - 5 parts of compatibilizer, 25 - 30 parts of flame retardant, 10 - 20 parts of glass fiber; The metal powder is a metallic element and / or metal oxide with a retained particle size D 50 ≤20 μm, and the retained length of the glass fiber is 0.5 to 2 mm.

2. The polypropylene metal composite material according to claim 1, characterized in that, In the components of the polypropylene metal composite material, the polypropylene is 25 - 35 weight parts, the metal powder is 20 - 30 weight parts, and the glass fiber is 13 - 17 weight parts.

3. The polypropylene metal composite material according to claim 1, characterized in that, The retention particle size D of the metal powder 50 is 13 to 19 μm.

4. The polypropylene metal composite material according to claim 1, characterized in that, The material of the metal powder is at least one of aluminum and its oxides, iron and its oxides, and steel.

5. The polypropylene metal composite material according to claim 1, wherein The melt mass flow rate of the polypropylene under the conditions of 230°C and 2.16 kg ≥ 20 g / 10 min.

6. The polypropylene metal composite material according to claim 5, characterized in that The melt mass flow rate of the polypropylene under the conditions of 230°C and 2.16 kg is 25 - 30 g / 10 min.

7. The polypropylene metal composite material according to claim 1, characterized in that The polypropylene metal composite material satisfies at least one of the following conditions: a. The polypropylene is block copolymerized polypropylene, or a mixture of block copolymerized polypropylene and homopolypropylene; b. The compatibilizer includes polyolefin graft maleic anhydride polymers; c. The flame retardant is a halogen-free flame retardant; d. The diameter of the glass fiber is 10 - 15 μm.

8. The polypropylene metal composite material according to any one of claims 1 to 7, characterized in that In the components of the polypropylene metal composite material, it further includes 0.2 - 1 weight part of processing aids; the processing aids include at least one of antioxidant, lubricant, and color powder.

9. The preparation method of the polypropylene metal composite material according to any one of claims 1 to 8, characterized in that, It includes the following steps: Mix each component evenly and melt extrude to obtain the polypropylene metal composite material.

10. Use of the polypropylene metal composite material according to any one of claims 1 - 8 in the preparation of parts of automobiles or electric bicycles.

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