Polypropylene composite material as well as preparation method and application thereof

Abstract

The invention relates to a polypropylene 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 composite material is prepared from the following components in parts by weight: 20 to 50 parts of homo-polypropylene, 20 to 50 parts of block co-polypropylene, 2 to 15 parts of octa-carbon POE (Polyolefin Elastomer), 15 to 35 parts of bromine-antimony flame retardant and 1 to 10 parts of maleic anhydride grafted polypropylene, the melt mass flow rate of the homo-polypropylene under the conditions of 230 DEG C and 2.16 kg is less than or equal to 35g / 10min; the melt mass flow rate of the block co-polypropylene under the conditions of 230 DEG C and 2.16 kg is 23 to 38 g / 10 min. The composite material formed by compounding the polypropylene composite material as matrix resin and continuous long glass fibers has good mechanical properties and low floating fibers.

Description

Technical Field

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

[0002] Polypropylene is a thermoplastic resin made by polymerizing propylene monomers. It is widely used in automotive instrument panels, battery pack housings, seat guards, bumpers and other parts because of its low density, good chemical stability, corrosion resistance, non-toxicity, good formability, good gloss of finished products, and high cost performance. However, due to the very low limiting oxygen index of polypropylene (about 18%), it is very easy to burn and is often accompanied by melt dripping and cast fire during the combustion process, which makes the flame easy to spread and cause serious fires.

[0003] Bromine antimony flame retardant is a commonly used high-efficiency flame retardant. The bromine element in it can not only react with the free radicals generated during combustion to inhibit the chain reaction of free radicals to slow down combustion, but also react with hydrogen in the combustion products to generate hydrogen bromide to further inhibit the combustion reaction. In addition, bromine antimony flame retardant can effectively absorb the heat in the combustion process to reduce the combustion temperature and slow down the combustion speed; it can also decompose at high temperatures to generate gases such as hydrogen bromide, and use these gases and the carbonized products generated by the combustion products to form a carbon layer that isolates oxygen, thereby effectively preventing the spread of flames. Therefore, modifying polypropylene with bromine antimony flame retardant can significantly improve its flame retardant properties.

[0004] However, research has found that although bromine antimony flame retardants can improve the flame retardancy of polypropylene, they will also cause the mechanical properties of flame-retardant polypropylene composites to decrease. It is often necessary to add fillers such as glass fibers to melt blend with polypropylene to improve its mechanical properties. Glass fibers are generally added through a side feed port and melt blended with polypropylene to reduce wear and maintain the length of the glass fibers; however, due to the compatibility issues between glass fibers and polypropylene and the "wick effect" of glass fibers, the mechanical properties and flame retardancy of polypropylene composites decrease.

[0005] To address this problem, people began to solve it by adding compatibilizers to enhance the compatibility between glass fiber and polypropylene and matching it with continuous long glass fibers; unlike short glass fibers, continuous long glass fibers cannot be added from the side feed port of the extruder to be melt-blended with the resin matrix like short glass fibers, and the continuous long glass fibers can only be fully impregnated in the polypropylene resin melt and stretched by a traction machine. In the actual production process, it was found that the polypropylene resin matrix would affect its impregnation effect on the long glass fibers, thereby affecting the mechanical properties of the polypropylene composite material and the floating fiber situation on its surface; therefore, a polypropylene material is needed that can fully impregnate the long glass fibers and make the composite material have both high mechanical properties and low floating fibers. Summary of the invention

[0006] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a polypropylene composite material and a preparation method and application thereof.

[0007] To achieve the above object, the technical solution adopted by the present invention is:

[0008] In a first aspect, the present invention provides a polypropylene composite material, comprising the following components in parts by weight:

[0009] Homopolymer polypropylene 20-50 parts, block copolymer polypropylene 20-50 parts, octa-carbon POE 2-15 parts, bromine antimony flame retardant 15-35 parts, maleic anhydride grafted polypropylene 1-10 parts;

[0010] The homopolymer polypropylene adopts ISO 1133-1:2022 standard, and the melt mass flow rate at 230° C. and 2.16 kg is ≤35 g / 10 min; the block copolymer polypropylene adopts ISO 1133-1:2022 standard, and the melt mass flow rate at 230° C. and 2.16 kg is 23 to 38 g / 10 min.

[0011] The present invention combines homopolypropylene with a specific melt flow rate with block copolymer polypropylene with a specific melt flow rate and octa-POE (ethylene-octene copolymer), and is matched with a bromine antimony flame retardant and a maleic anhydride grafted polypropylene compatibilizer to form a polypropylene composite melt with suitable fluidity; when the polypropylene composite melt is compounded with continuous long glass fibers, it can easily penetrate between glass fiber bundles and wrap around the surface of each glass fiber as much as possible to effectively improve the floating fiber situation, while maintaining the highly oriented structure of the long glass fibers, thereby having excellent mechanical properties; and the bromine antimony flame retardant that enters and is uniformly dispersed between the glass fibers along with the polypropylene composite melt can work together with the long glass fibers to significantly improve the flame retardant stability.

[0012] Preferably, the total mass fraction of homopolypropylene and block copolymer polypropylene in the polypropylene composite material is preferably greater than or equal to 40%. Optionally, the weight fraction of homopolypropylene in the polypropylene composite material can be 25 parts, 30 parts, 35 parts, 40 parts, 45 parts, 25 parts, 30 parts, 35 parts, 40 parts, 45 parts, 4 parts, 6 parts, 8 parts, 10 parts, 12 parts, 14 parts, 16 parts, 18 parts, 20 parts, 24 parts, 28 parts, 32 parts, and 2 parts, 4 parts, 6 parts, 8 parts, 8 parts, 10 parts, 12 parts, 14 parts, 16 parts, 18 parts, 20 parts, 24 parts, 28 parts, 32 parts, and 2 parts, 4 parts, 6 parts, 8 parts, of maleic anhydride grafted polypropylene.

[0013] As a preferred embodiment of the polypropylene composite material of the present invention, the polypropylene composite material comprises the following components by weight: 25 to 45 parts of homopolymer polypropylene, 25 to 45 parts of block copolymer polypropylene, 4 to 12 parts of octa-carbon POE, 20 to 30 parts of bromine antimony flame retardant, and 3 to 8 parts of maleic anhydride grafted polypropylene.

[0014] As a preferred embodiment of the polypropylene composite material of the present invention, the homopolypropylene adopts the ISO1133-1:2022 standard, and the melt mass flow rate at 230°C and 2.16kg is 17-32g / 10min. Optionally, the melt mass flow rate of the homopolypropylene can be 15g / 10min, 17g / 10min, 20g / 10min, 22g / 10min, 24g / 10min, 26g / 10min, 28g / 10min, 30g / 10min, 33g / 10min. Studies have found that the melt flow rate of homopolypropylene affects the melt fluidity of the polypropylene composite material, thereby affecting the difficulty of its immersion in long glass fibers and the wrapping performance of glass fibers; when the melt mass flow rate of homopolypropylene is 17-32g / 10min, it can better immerse the long glass fibers to enhance the composite effect of the two, improve the floating fiber and maintain better rigidity.

[0015] As a preferred embodiment of the polypropylene composite material of the present invention, the block copolymer polypropylene adopts the ISO1133-1:2022 standard, and the melt mass flow rate at 230°C and 2.16kg is 25 to 35g / 10min. Optionally, the melt mass flow rate of the block copolymer polypropylene can be specifically 24g / 10min, 26g / 10min, 28g / 10min, 30g / 10min, 32g / 10min, 34g / 10min, and 36g / 10min. Studies have found that the block copolymer polypropylene with the above melt mass flow rate can better cooperate with homopolymer polypropylene, so that the polypropylene composite material has a suitable viscosity under heating and melting conditions, which can not only fully wet the long glass fiber, but also significantly improve the toughness of the material.

[0016] As a preferred embodiment of the polypropylene composite material of the present invention, the eight-carbon POE adopts the ISO 1133-1:2022 standard, and the melt mass flow rate at 190°C and 2.16kg is 5 to 15g / 10min. Optionally, the melt mass flow rate of the eight-carbon POE can be 3g / 10min, 6g / 10min, 8g / 10min, 10g / 10min, 13g / 10min, and 16g / 10min. Studies have found that the eight-carbon POE with the above melt mass flow rate can not only maintain good melt fluidity of the polypropylene composite material, but also synergize with the block copolymer polypropylene to improve the toughness of the material.

[0017] As a preferred embodiment of the polypropylene composite material of the present invention, the polypropylene composite material further comprises 0.1 to 1 parts by weight of an antioxidant and 0.1 to 1 parts by weight of a lubricant. Optionally, the antioxidant may be at least one of a hindered phenolic primary antioxidant, a phosphite or thioether secondary antioxidant, and the lubricant may be at least one of a metal soap lubricant, a stearic acid complex ester lubricant, and an amide lubricant.

[0018] In a second aspect, the present invention provides a method for preparing the above-mentioned polypropylene composite material, comprising the following steps: mixing the components uniformly and then melt-extruding to obtain the polypropylene composite material.

[0019] In a third aspect, the present invention provides use of the above-mentioned polypropylene composite material in preparing a continuous long glass fiber reinforced polypropylene flame retardant material.

[0020] In a fourth aspect, the present invention provides a continuous long glass fiber reinforced polypropylene flame retardant material, which comprises the above polypropylene composite material and glass fiber, wherein the diameter of the glass fiber is 15-20 μm, such as EDR17-2400-988A of Jushi Group.

[0021] As a preferred embodiment of the continuous long glass fiber reinforced polypropylene flame retardant material of the present invention, the mass ratio of the polypropylene composite material to the glass fiber is (60-80): (20-40). Optionally, in parts by weight, the polypropylene composite material can be 62 parts, 64 parts, 66 parts, 68 parts, 70 parts, 72 parts, 74 parts, 76 parts, 78 parts; the glass fiber can be 22 parts, 24 parts, 26 parts, 28 parts, 30 parts, 32 parts, 34 parts, 36 parts, 38 parts.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The present invention combines homopolymer polypropylene with a specific melt flow rate with block copolymer polypropylene with a specific melt flow rate and octa-carbon POE, and simultaneously uses a bromine antimony flame retardant and a maleic anhydride grafted polypropylene compatibilizer to form a polypropylene composite material melt with suitable fluidity; when the polypropylene composite material melt is compounded with continuous long glass fibers, it can easily penetrate between glass fiber bundles and wrap around the surface of each glass fiber as much as possible to effectively improve the floating fiber situation, while maintaining the highly oriented structure of the long glass fibers, thereby having excellent mechanical properties; and the bromine antimony flame retardant that enters into and is uniformly dispersed between the glass fibers along with the polypropylene composite material melt can work together with the long glass fibers to significantly improve the flame retardant properties. DETAILED DESCRIPTION

[0024] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0025] Unless otherwise specified, other materials, reagents, etc. used in the examples and comparative examples can be obtained from commercial sources.

[0026] 1. Raw materials and reagents

[0027] Homopolymer polypropylene-1, melt mass flow rate is 32g / 10min, brand is PP 320 powder, manufacturer is Maoming Shihua;

[0028] Homopolymer polypropylene-2, melt mass flow rate is 17g / 10min, brand is PP M17HN, manufacturer is Hainan Petrochemical;

[0029] Homopolymer polypropylene-3, melt mass flow rate is 55g / 10min, brand is PP H9018H, manufacturer is Lanzhou Petrochemical;

[0030] Block copolymer polypropylene-1, melt mass flow rate is 25g / 10min, brand is PP EP548R, manufacturer is Zhenhai Petrochemical;

[0031] Block copolymer polypropylene-2, melt mass flow rate is 35g / 10min, brand is PP K9930H (FP), manufacturer is Guangzhou Petrochemical;

[0032] Block copolymer polypropylene-3, melt mass flow rate is 12g / 10min, brand is PP M09, manufacturer is Wuhan Petrochemical;

[0033] Block copolymer polypropylene-4, melt mass flow rate is 50g / 10min, brand is PP EP648U, manufacturer is Sinochem Refining;

[0034] Eight-carbon POE-1 (ethylene-octene copolymer), melt mass flow rate is 13g / 10min, brand is POE8137, manufacturer is Dow Chemical;

[0035] Eight-carbon POE-2 (ethylene-octene copolymer), melt mass flow rate is 5g / 10min, brand is POE 875L, manufacturer is SK Chemical of South Korea;

[0036] The melt mass flow rate of tetra-carbon POE (ethylene-butene copolymer) is 5 g / 10 min, the brand is POE 7447, and the manufacturer is Dow Chemical;

[0037] The bromine antimony flame retardant is composed of bromine flame retardant (brand name H-02NF, manufacturer Taizhou Baili Chemical) and antimony white (brand name S-12N, manufacturer Hunan Shanxing Antimony Industry) in a mass ratio of 3:1;

[0038] Maleic anhydride grafted polypropylene, brand name AD-105, manufacturer: Foshan Bochen;

[0039] The processing aid is obtained by compounding antioxidant Y-001 and lubricant EBS B50 in a mass ratio of 1:1;

[0040] Continuous long glass fiber, brand EDR17-2400-988A, manufacturer is Jushi Group.

[0041] The melt mass flow rates of the above homopolymer polypropylene and block copolymer polypropylene are measured at 230°C and 2.16kg using the ISO 1133-1:2022 standard; the melt mass flow rates of the eight-carbon POE and the four-carbon POE are measured at 190°C and 2.16kg using the ISO1133-1:2022 standard.

[0042] 2. Polypropylene composite materials 1-12

[0043] Table 1 Weight parts of each component of polypropylene composite materials 1 to 12

[0044]

[0045]

[0046] The method for preparing the polypropylene composite material comprises the following steps:

[0047] According to the formula, the components are mixed evenly and then added into a twin-screw extruder for melt extrusion to obtain a polypropylene composite material; the aspect ratio of the twin-screw extruder is 40:1, and the temperature settings of the twin-screw extruder are: 200-230°C for zone one, 220-240°C for zones two to five, and 240-260°C for other zones.

[0048] 3. Examples 1 to 10 and Comparative Examples 1 to 4

[0049] Table 2 Weight percentage of each component in the continuous long glass fiber reinforced polypropylene flame retardant material in each embodiment and comparative example

[0050]

[0051]

[0052] The method for preparing the above-mentioned continuous long glass fiber reinforced polypropylene flame retardant material comprises the following steps:

[0053] The molten polypropylene composite material is added into an impregnation mold containing continuous long glass fibers, so that the molten polypropylene composite material is evenly dispersed between the preheated continuous long glass fibers, and then water-cooled and sent into a pelletizer for pelletizing (10±2mm long particles) under the action of a traction machine to obtain a continuous long glass fiber reinforced polypropylene flame retardant material.

[0054] 4. Performance Testing

[0055] 1) Surface floating fiber index: The continuous long glass fiber reinforced polypropylene flame retardant material in each embodiment and comparative example is injection molded into a square plate (100mm×100mm×2mm), and then the surface morphology of the square plate is scanned by two-dimensional element to obtain a surface image, which is then converted into black and white pixels using ImageJ. The area percentage occupied by the white pixels (corresponding to the floating fibers on the surface) is calculated (defined as the floating fiber index), thereby achieving quantitative characterization of the floating fiber phenomenon. The better the floating fibers, the smaller the value.

[0056] 2) Drop test: The continuous long glass fiber reinforced polypropylene flame retardant material in each embodiment and comparative example was injection molded into a square plate (100 mm×100 mm×2 mm), and then a falling ball weighing 500 g was placed in a special pipe and allowed to fall freely at different distances to measure the height at which the square plate did not crack.

[0057] 3) Izod notch impact strength: tested using ISO 180 standard, test conditions: Type A notch: 4mm thick machine-milled notch, 23°C.

[0058] Table 3 Performance of continuous long glass fiber reinforced polypropylene flame retardant materials in various embodiments and comparative examples

[0059]

[0060]

[0061] According to the data in Table 3, the floating fiber index of the continuous long glass fiber reinforced polypropylene flame retardant materials in Examples 1 to 10 is less than or equal to 0.56, and the drop height is greater than or equal to 135 cm, and the cantilever beam notch impact strength reaches 20 kJ / m 2 The above indicates that when the polypropylene composite material melt of the present invention is compounded with continuous long glass fibers, it can not only easily penetrate between glass fiber bundles to impart mechanical properties to the continuous long glass fiber reinforced polypropylene flame retardant material, but also work together with the long glass fibers to improve the flame retardant properties.

[0062] At the same time, according to Comparative Example 2, when the melt mass flow rate of the block copolymer polypropylene is too small, it is easy to cause the wettability of the polypropylene composite material to the continuous long glass fiber to deteriorate, making it difficult for the polypropylene composite material to fully enter and evenly disperse between the glass fiber bundles, thereby causing the continuous long glass fiber reinforced polypropylene flame retardant material to have serious floating fibers and poor mechanical properties; and according to Comparative Examples 1 and 3, it can be seen that when the melt flow rate of the homopolymer polypropylene or the block copolymer polypropylene is too large, although it can promote the uniform dispersion of the polypropylene composite material in the glass fiber bundle to a certain extent, it is difficult to simultaneously improve the notched impact strength of the continuous long glass fiber reinforced polypropylene flame retardant material; in addition, according to Comparative Example 4, it can be found that when the four-carbon POE is combined with the homopolymer polypropylene and the block copolymer polypropylene of a specific melt flow rate, it is difficult to effectively improve the floating fibers and mechanical properties of the continuous long glass fiber reinforced polypropylene flame retardant material at the same time.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A polypropylene composite material, characterized in that: By weight, it includes the following components: Homopolymer polypropylene 20-50 parts, block copolymer polypropylene 20-50 parts, octa-carbon POE 2-15 parts, bromine antimony flame retardant 15-35 parts, maleic anhydride grafted polypropylene 1-10 parts; The melt mass flow rate of the homopolypropylene at 230° C. and 2.16 kg is ≤35 g / 10 min; The melt mass flow rate of the block copolymer polypropylene at 230° C. and 2.16 kg is 23-38 g / 10 min.

2. The polypropylene composite material according to claim 1, characterized in that The composition comprises the following components by weight: 25-45 parts of homopolymer polypropylene, 25-45 parts of block copolymer polypropylene, 4-12 parts of octa-carbon POE, 20-30 parts of bromine antimony flame retardant and 3-8 parts of maleic anhydride grafted polypropylene.

3. The polypropylene composite material according to claim 1, characterized in that: The melt mass flow rate of the homopolypropylene at 230° C. and 2.16 kg is 17 to 32 g / 10 min.

4. The polypropylene composite material according to claim 1, characterized in that: The melt mass flow rate of the block copolymer polypropylene at 230° C. and 2.16 kg is 25 to 35 g / 10 min.

5. The polypropylene composite material according to claim 1, characterized in that: The melt mass flow rate of the eight-carbon POE at 190° C. and 2.16 kg is 5 to 15 g / 10 min.

6. The polypropylene composite material according to claim 1, characterized in that: The invention also comprises 0.1 to 1 parts by weight of an antioxidant and 0.1 to 1 parts by weight of a lubricant.

7. The method for preparing the polypropylene composite material according to any one of claims 1 to 6, characterized in that: The method comprises the following steps: mixing the components uniformly and then melting and extruding the components to obtain a polypropylene composite material.

8. Use of the polypropylene composite material according to any one of claims 1 to 6 in the preparation of continuous long glass fiber reinforced polypropylene flame retardant material.

9. A continuous long glass fiber reinforced polypropylene flame retardant material, characterized in that: The invention comprises the polypropylene composite material according to any one of claims 1 to 6 and glass fiber.

10. The continuous long glass fiber reinforced polypropylene flame retardant material according to claim 9, characterized in that: The mass ratio of the polypropylene composite material to the glass fiber is (60-80):(20-40).

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