Polypropylene / polyurethane composite material as well as preparation method and application thereof

Abstract

The invention relates to a polypropylene / polyurethane composite material as well as a preparation method and application thereof. The polypropylene / polyurethane composite material comprises the following components in parts by weight: 30-80 parts of polypropylene; 5 to 50 parts of polyurethane; 2 to 55 parts of plant fiber; 1-10 parts of a compatilizer; and 10-30 parts of an ammonium / amine phosphate flame retardant. The composite material provided by the invention can effectively overcome the defects that in the prior art, the flame retardance and the mechanical property of a polypropylene composite material are difficult to consider at the same time, and the scratch resistance and the wear resistance are poor through the synergistic compounding effect of all the components.

Description

Technical Field

[0001] This invention relates to the field of polymer composite materials technology, and in particular to a polypropylene / polyurethane composite material, its preparation method, and its application. Background Technology

[0002] Polypropylene, as a general-purpose plastic, is widely used in various fields due to its low density, good chemical stability, and excellent processing performance. However, pure polypropylene has poor flame retardancy, a low limiting oxygen index, and is prone to fracture under external force, resulting in insufficient impact strength. This limits its application in situations requiring high flame retardancy and mechanical properties.

[0003] To improve the properties of polypropylene, researchers often use the addition of plant fibers for reinforcement. Plant fibers are widely available, inexpensive, and renewable; introducing them into the polypropylene matrix can improve the material's mechanical properties to some extent. However, plant fibers contain a large number of hydroxyl groups on their surface, making them highly polar, while polypropylene is a non-polar polymer. The poor compatibility between the two results in limited improvement in the mechanical properties of the composite material.

[0004] Meanwhile, flame retardants are usually added to impart flame retardant properties to polypropylene composites. However, when flame retardants are added alone, a high amount is required to achieve the desired flame retardant effect, which leads to a decrease in the mechanical properties of the composite material, and the scratch resistance and abrasion resistance of the material are also difficult to meet the requirements of practical applications.

[0005] Therefore, providing a polypropylene composite material that significantly improves its mechanical properties, scratch resistance, and wear resistance while enhancing its flame retardant properties is a technical challenge that urgently needs to be addressed. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a polypropylene / polyurethane composite material, its preparation method, and its applications. The composite material provided by this invention, through the synergistic effect of its components, effectively overcomes the shortcomings of existing polypropylene composite materials, such as difficulty in simultaneously achieving flame retardancy and mechanical properties, as well as poor scratch and abrasion resistance.

[0007] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides a polypropylene / polyurethane composite material, wherein the polypropylene / polyurethane composite material comprises the following components in parts by weight: 30-80 parts of polypropylene; 5-50 parts of polyurethane; 2-55 parts plant fiber; 1-10 parts compatibilizer; 10-30 parts of ammonium / amine phosphate flame retardant.

[0008] In this invention, based on the phosphorus-nitrogen expansion-type halogen-free flame retardant mechanism, the acid source, carbon source, and gas source work synergistically. Specifically, ammonium / amine phosphate flame retardants decompose at high temperatures to generate phosphoric acid, which catalyzes the dehydration of the carbon source to form a char layer. Plant fibers, primarily composed of cellulose, hemicellulose, and other polyol components, can serve as a carbon source and exhibit a synergistic flame retardant effect. Polyurethane monomers, consisting of polyols and isocyanates, can act as auxiliary carbon and gas sources during combustion, also exhibiting a synergistic flame retardant effect. The combination of these three components improves flame retardant efficiency, reduces the proportion of flame retardant added, and enhances the flame retardant and mechanical properties of the material.

[0009] Meanwhile, the addition of polyurethane can effectively improve the toughness of the composite material, plant fibers play a reinforcing role, and compatibilizers improve the interfacial compatibility between plant fibers, polyurethane and polypropylene matrix, thereby improving the overall performance of the composite material.

[0010] The polypropylene / polyurethane composite material provided by this invention utilizes the synergistic effect between the components to obtain a composite material with excellent flame retardant properties, significantly improved mechanical properties, and excellent scratch resistance and wear resistance. It can be widely used in automotive parts, electronic and electrical housings, building materials and other fields.

[0011] In this invention, the polypropylene / polyurethane composite material may contain, for example, 30 parts, 40 parts, 50 parts, 60 parts, 70 parts, 80 parts, etc., preferably 30-70 parts; the polyurethane may contain, for example, 5 parts, 15 parts, 25 parts, 35 parts, 45 parts, 50 parts, etc., preferably 25-50 parts; the plant fiber may contain, for example, 2 parts, 5 parts, 15 parts, 25 parts, 35 parts, 45 parts, 50 parts, 55 parts, etc., preferably 5-50 parts; the compatibilizer may contain, for example, 1 part, 2 parts, 5 parts, 8 parts, 10 parts, etc., preferably 3-9 parts; and the ammonium / amine phosphate flame retardant may contain, for example, 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, etc., preferably 10-28 parts.

[0012] Preferably, in the polypropylene / polyurethane composite material, the mass percentage of polypropylene is 30-55%, more preferably 30-40%.

[0013] Preferably, in the polypropylene / polyurethane composite material, the mass percentage of polyurethane is 3-52%, more preferably 12-52%.

[0014] Preferably, the plant fiber content in the polypropylene / polyurethane composite material is 2-30% by mass, and more preferably 5-28%.

[0015] Preferably, the compatibilizer in the polypropylene / polyurethane composite material has a mass percentage content of 0.5-5%, more preferably 3-5%.

[0016] Preferably, the mass percentage of ammonium / amine phosphate flame retardant in the polypropylene / polyurethane composite material is 8-22%, more preferably 10-16%.

[0017] Preferably, the polypropylene includes homopolymer polypropylene and / or copolymer polypropylene.

[0018] Preferably, the melt index of the polypropylene at 230°C and 2.16 kg is 0.3~100 g / 10 min (e.g., 0.3 g / 10 min, 0.5 g / 10 min, 3 g / 10 min, 10 g / 10 min, 30 g / 10 min, 60 g / 10 min, 90 g / 10 min, 100 g / 10 min, etc.).

[0019] In this invention, the test method for the melt index of polypropylene is GB_T_3682.1.

[0020] Preferably, the polyurethane is a thermoplastic polyurethane elastomer.

[0021] Preferably, the Shore hardness of the polyurethane is 30-80D (e.g., 30D, 40D, 50D, 60D, 70D, 80D, etc.), and more preferably 45-75D.

[0022] In this invention, polyurethane is preferably a material with higher Shore hardness. High-hardness polyurethane can improve the mechanical strength and surface hardness of the material, and improve the surface hardness and scratch resistance of polypropylene material.

[0023] In this invention, the standard for testing the Shore hardness of polyurethane is GB / T2411-2008 Plastics and hard rubbers using a hardness tester to determine indentation hardness (Shore hardness).

[0024] Preferably, the plant fiber includes any one or a combination of at least two of wood flour, bamboo fiber, hemp fiber or rice husk fiber, preferably bamboo fiber and / or hemp fiber.

[0025] In this invention, plant fibers are preferably high-strength materials, which have the advantages of high strength, high modulus and low density.

[0026] Preferably, the length of the plant fiber is 0.1~120mm (e.g., 0.1mm, 1mm, 5mm, 10mm, 50mm, 100mm, 120mm, etc.), and more preferably 5~100mm.

[0027] Preferably, the compatibilizer comprises maleic anhydride-grafted polypropylene and / or maleic anhydride-grafted ethylene-octene copolymer.

[0028] Preferably, the ammonium / amine phosphate flame retardant includes any one or a combination of at least two of ammonium polyphosphate, melamine polyphosphate, or piperazine pyrophosphate.

[0029] Furthermore, the polypropylene / polyurethane composite material provided by the present invention also includes additives, which include 0.01-1 parts of antioxidant and 0.01-1 parts of lubricant.

[0030] The antioxidants described in this invention can be selected with reference to existing technologies, such as, but not limited to, one or more of phenolic antioxidants, phosphite antioxidants, divalent sulfur antioxidants, or hindered amine antioxidants.

[0031] Specifically, the phenolic antioxidants include 2,6-di-tert-butyl-4-methylphenol (antioxidant 264), pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (antioxidant 1010), N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexamethylenediamine (antioxidant 1098), n-octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (antioxidant 1076), styrene-modified phenol (anti-aging agent SP), 2, 2'-Methylenebis(4-methyl-6-tert-butylphenol) (antioxidant 2246), 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane (antioxidant CA), 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene (antioxidant 330), and 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl) (antioxidant 3114); the phosphite antioxidants include tris(nonylphenyl) phosphite (antioxidant TNP), antioxidant ODP (the reaction product of N-phenylaniline and 2,4,4-trimethylpentene), tri[ The antioxidant comprises one or more of the following: 2,4-di-tert-butylphenyl]phosphite (antioxidant 168), bis(4-octylphenol) diphosphate (antioxidant 1093), or diethyl 3,5-di-tert-butyl-4-hydroxybenzoate (antioxidant 1222); the divalent sulfur antioxidants include dilaurate thiodipropionate (DLTP) and / or distearate thiodipropionate (DSTP); the hindered amine antioxidants include one or more of the following: LS-744, bis-2,2,6,6-tetramethylpiperidinol sebacate (such as LS-770), tris(1,2,2,6,6-pentamethylpiperidinol) phosphite (GW-540), or Flamstab NOR116.

[0032] The lubricant described in this invention can be selected with reference to existing technologies, such as, but not limited to, one or more of low molecular weight esters, metal soaps, stearic acid complex esters, and amides.

[0033] Specifically, the low-molecular-weight lipids include one or more of solid paraffin, liquid paraffin, or low-molecular-weight polyolefin waxes; the metal soaps include one or more of calcium stearate, magnesium stearate, zinc stearate, or barium stearate; the stearic acid complex esters include one or more of ethylene glycol stearate, glyceryl stearate, or pentaerythritol stearate; and the amides include one or more of erucamide, methylene bis-stearamide, or N,N-ethylene bis-stearamide.

[0034] In a second aspect, the present invention provides a method for preparing a polypropylene / polyurethane composite material according to the first aspect, the method comprising: mixing the components, followed by melt extrusion, cooling granulation and injection molding to obtain the polypropylene / polyurethane composite material.

[0035] Preferably, the plant fibers are further subjected to a drying process before mixing.

[0036] Thirdly, the present invention provides an application of the polypropylene / polyurethane composite material according to the first aspect in automotive parts, electronic and electrical housings, or building materials.

[0037] Fourthly, the present invention provides a component formed from the polypropylene / polyurethane composite material described in the first aspect.

[0038] In this invention, the component can be a lithium-ion battery casing, a household appliance control box, a building template, etc. The molding process can include injection molding, vacuum forming, compression molding, etc.

[0039] Compared with the prior art, the present invention has at least the following beneficial effects: The polypropylene / polyurethane composite material provided by this invention utilizes the synergistic effect between its components, resulting in a composite material with excellent flame retardant properties, significantly improved mechanical properties, and also excellent scratch resistance and abrasion resistance. It can be widely used in automotive parts, electronic and electrical housings, building materials, and other fields. Furthermore, the preparation method of the composite material provided by this invention is simple, convenient, and suitable for industrial production. Detailed Implementation

[0040] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0041] The materials used in the following embodiments are from the following sources: A. Polypropylene A-1: Homopolymer polypropylene, grade V30G, manufactured by Sinopec; A-2: Copolymer polypropylene, grade K8003, manufactured by Sinopec; B. Polyurethane B-1: Hardness 48D, Grade Elastollan 1195A, Manufacturer BASF; B-2: Hardness 73D, Grade Elastollan 1174D, Manufacturer BASF; B-3: Hardness 36D, Grade Elastollan 1185A, Manufacturer BASF; C. Plant fiber C-1: Bamboo fiber, length 50~100mm, brand name bamboo raw fiber, manufacturer Hebei Jigao Chemical Fiber Co., Ltd.; C-2: Hemp fiber, 5~10mm in length, grade short-cut sisal fiber, manufactured by Guangzhou Sisal Research Institute; C-3: Wood flour, length 0.1~1mm, grade 80 mesh pine wood flour, manufacturer Shijiazhuang Qiadian New Material Technology Co., Ltd.; C-4: Rice husk fiber, 2~4mm in length, brand name rice husk powder, manufacturer Shijiazhuang Qiadian New Material Technology Co., Ltd.; D. Compatibilizer D-1: Maleic anhydride-grafted polypropylene, PP-g-MAH, grade PC-3, manufacturer: Nanhai Baichen Polymer New Materials Co., Ltd. E. Flame retardants E-1: Ammonium polyphosphate, APP, manufactured by Hangzhou Jiersi Flame Retardant Chemical Co., Ltd. E-2: Piperazine pyrophosphate, MPP, manufactured by Hangzhou Jiersi Flame Retardant Chemical Co., Ltd. E-3: Magnesium hydroxide, Western Mining; Glass fiber, ECS13-04-508A, Jushi Group. Examples 1-10, Comparative Examples 1-4 Examples 1-10 and Comparative Examples 1-4 each provide a polypropylene / polyurethane composite material, the components and weight parts of which are shown in Table 1 and Table 2 (" / " indicates that it does not exist).

[0042] The preparation methods of the above embodiments and comparative examples include the following steps: (1) Raw material pretreatment: Place the plant fiber in an oven at 100℃ and dry for 6 hours for later use; (2) Mixing: Add polypropylene, thermoplastic polyurethane elastomer, pretreated plant fiber, compatibilizer and flame retardant to a high-speed mixer according to the weight parts shown in the table, and mix for 10 minutes at a speed of 1000 r / min to obtain a mixture. (3) Melt blending extrusion: The mixture is added to a twin-screw extruder for melt blending extrusion. The temperature of each zone of the extruder is 170~200℃ and the screw speed is 200r / min. After extrusion, the mixture is cooled by water and pelletized to obtain composite material particles. (4) Molding: The composite material particles are dried at 90°C for 3 hours, and then injection molded by injection molding machine. The injection temperature is 180~220°C and the injection pressure is 70MPa to obtain polypropylene / polyurethane composite material.

[0043] The polypropylene / polyurethane composite materials provided in the above embodiments and comparative examples were subjected to the following performance tests, and the results are shown in Tables 1 and 2.

[0044] (1) Tensile strength: tested in accordance with GB / T 1040.1-2018; (2) Impact strength: Tested in accordance with GB / T 1843-2008; (3) Flame retardant performance: tested according to UL94 standard; (4) Scratch resistance: Tested according to GB / T 3903.29-2008; (5) Abrasion resistance: Tested in accordance with GB / T 5478-2008.

[0045] Table 1 Table 2 Combining the test results in Tables 1 and 2, we can see that: As can be seen from Examples 1 to 10, the present invention, through the rational compounding of polypropylene, polyurethane, plant fiber, compatibilizer, and ammonium / amine phosphate flame retardant in appropriate proportions, exhibits a synergistic effect among the components, resulting in a composite material with excellent flame retardant properties, achieving UL94 V0 rating; simultaneously, the mechanical properties are significantly improved, with tensile strength of 42~87MPa and impact strength of 16~58kJ / m. 2 It also has excellent scratch resistance and wear resistance, with a scratch load of 3.5~9.6N and an wear rate of 1~18mg / 1000 cycles.

[0046] A comparison of Examples 1, 5, and 6 shows that the present invention is more preferably made of high-hardness polyurethane. When polyurethane with lower hardness is used, the tensile strength and scratch resistance of the resulting composite material are significantly reduced. A comparison of Examples 1, 7, and Examples 8-9 shows that the present invention is more preferably made of high-strength fibers such as bamboo fiber and hemp fiber. When wood flour or rice husk fiber is used, the fiber length is smaller, and the improvement in the mechanical properties of the material, such as tensile strength and impact strength, is smaller.

[0047] A comparison of Example 1 and Comparative Examples 1-2 shows that when polyurethane is lacking in the composite material, the tensile, impact, scratch and abrasion resistance properties are significantly reduced, and the flame retardant properties also decrease. When plant fibers are lacking, the impact resistance, scratch and abrasion resistance properties decrease. A comparison of Example 1 and Comparative Example 3 shows that when ammonium / amine phosphate flame retardants are replaced with magnesium hydroxide flame retardants, the flame retardant properties decrease. A comparison of Example 1 and Comparative Example 4 shows that after replacing plant fibers with glass fibers, the impact and flame retardant properties decrease, while the tensile strength and abrasion resistance increase. Considering the overall tensile, impact, scratch and abrasion resistance, and flame retardant properties, plant fibers are superior to glass fibers.

[0048] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A polypropylene / polyurethane composite material, characterized in that, The polypropylene / polyurethane composite material comprises the following components by weight: 30-80 parts of polypropylene; 5-50 parts of polyurethane; 2-55 parts plant fiber; 1-10 parts compatibilizer; 10-30 parts of ammonium / amine phosphate flame retardant.

2. The polypropylene / polyurethane composite material according to claim 1, characterized in that, The polypropylene includes homopolymer polypropylene and / or copolymer polypropylene.

3. The polypropylene / polyurethane composite material according to claim 1, characterized in that, The polyurethane is a thermoplastic polyurethane elastomer.

4. The polypropylene / polyurethane composite material according to claim 1, characterized in that, The polyurethane has a Shore hardness of 30-80D, preferably 45-75D.

5. The polypropylene / polyurethane composite material according to claim 1, characterized in that, The plant fiber includes any one or a combination of at least two of wood flour, bamboo fiber, hemp fiber or rice husk fiber, preferably bamboo fiber and / or hemp fiber.

6. The polypropylene / polyurethane composite material according to claim 1, characterized in that, The length of the plant fiber is 0.1~120mm, preferably 5~100mm.

7. The polypropylene / polyurethane composite material according to claim 1, characterized in that, The compatibilizer includes maleic anhydride-grafted polypropylene and / or maleic anhydride-grafted ethylene-octene copolymer. Preferably, the ammonium / amine phosphate flame retardant includes any one or a combination of at least two of ammonium polyphosphate, melamine polyphosphate, or piperazine pyrophosphate.

8. A method for preparing a polypropylene / polyurethane composite material according to any one of claims 1 to 7, characterized in that, The preparation method includes: mixing the components, followed by melt extrusion, cooling granulation, and injection molding to obtain the polypropylene / polyurethane composite material.

9. The application of a polypropylene / polyurethane composite material according to any one of claims 1 to 7 in automotive parts, electronic and electrical housings, or building materials.

10. A component, characterized in that, The part is formed by injection molding, vacuum forming or compression molding of the polypropylene / polyurethane composite material according to any one of claims 1 to 7.

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