A glass fiber reinforced polypropylene composite and a method for producing the same

Abstract

The application discloses a glass fiber reinforced polypropylene composite material and a preparation method thereof. The glass fiber reinforced polypropylene composite material contains the following raw materials in percentage by mass: modified copolymerized polypropylene 45.5%-75%, glass fiber 10%-26%, toughening agent 3%-9%, coupling agent 3.5%-12.0%, compatibilizer 4%-7% and stabilizer 0.4%-0.6%; wherein, the coupling agent contains at least two primary amines, and the modified copolymerized polypropylene contains aldehyde groups. The glass fiber reinforced polypropylene composite material provided by the application forms a macromolecular network structure with reversible cross-linking through mutual cooperation between the raw materials, significantly improves the notched impact strength of the glass fiber reinforced polypropylene composite material on the basis of improving the strength and low-temperature resistance of the glass fiber reinforced polypropylene composite material, and has excellent comprehensive performance.

Description

Technical Field

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

[0002] Polypropylene (PP) is an important thermoplastic material with stable properties, easy molding and processing, and low cost, making it widely used in textiles, packaging, and food industries. However, with its expanding applications, its shortcomings in strength and low-temperature resistance have become increasingly apparent, making it difficult to meet the requirements of high-performance products. Glass fiber reinforced polypropylene composites show significant improvements in strength and low-temperature resistance. However, due to the poor compatibility between the non-polar material PP and glass fiber, glass fiber reinforcement of PP typically involves first grafting reactive functional groups onto the PP, treating the glass fiber with a coupling agent, and finally extruding and granulating both together. This results in a significant decrease in the notched impact strength of the resulting composite material.

[0003] For example, Chinese patent document CN105418852A discloses a low-odor, low-emission glass fiber reinforced polypropylene composition. The specific preparation method involves mixing polypropylene, antioxidants, lubricants, and coating agents, then adding the mixture to a twin-screw extruder. Next, a diluent-diluted functional monomer and initiator are added through a micro-injection system. Grafting is activated by ultrasonication. Finally, glass fibers and a VOC extractant are added sequentially from the side feed port. After melt plasticizing, extrusion, and granulation, the low-odor, low-emission glass fiber reinforced polypropylene is obtained. The glass fiber reinforced polypropylene material prepared in this document has a melt flow rate of up to 21 g / 10 min and a flexural modulus exceeding 3000 MPa, but its notched impact strength is only up to 16.8 kJ / m. 2 Chinese patent document CN104311998A discloses a high-flowability glass fiber reinforced polypropylene composite material, comprising polypropylene, glass fiber, toughening agent, polyester wax, metal soap, rheology modifier, thermo-oxidative stabilizer, and antioxidant. By adding appropriate amounts of composite lubricant and rheology modifier, the processing performance of the composite material is improved. The glass fiber reinforced polypropylene prepared in this document has a maximum flow rate of 34 g / 10 min and a flexural modulus of around 4000 MPa, but the highest notched impact strength is only 6 kJ / m. 2Chinese patent document CN103788490A discloses a low-float, high-gloss glass fiber reinforced polypropylene composite material and its preparation method. This composite material includes polypropylene, polyethylene, calcium sulfate whiskers, glass fiber, elastomer, compatibilizer, and antioxidant. By replacing some of the glass fiber with calcium sulfate whiskers, the inherent strength of the composite material is maintained while reducing the amount of glass fiber, lowering the float, and improving the surface gloss. The glass fiber reinforced polypropylene prepared in this document has a maximum flow rate of 20 g / 10 min and a maximum flexural modulus of approximately 4000 MPa, but its maximum notched impact strength is only 14.9 kJ / m. 2 Chinese patent document CN102532682A discloses a low-warpage, high-gloss filled reinforced polypropylene material and its preparation method, comprising homopolymer polypropylene, glass fiber, wollastonite, compatibilizer, and nucleating agent as raw materials. This document improves the surface gloss of the material by adding an appropriate amount of wollastonite to the glass fiber reinforced polypropylene system, making it suitable for injection molding products such as automotive glove boxes. The glass fiber reinforced polypropylene prepared in this document has a flexural modulus of up to 7000 MPa, but its notched impact strength is only 7.5 kJ / m. 2 .

[0004] Inspired by thermoplastic elastomers, dynamic covalent bonds have been introduced into traditional rubber to prepare elastomer materials that combine reproducible processability and excellent crosslinking properties. Dynamic covalent bonds are covalent bonds that can reversibly break / bond upon exposure to specific stimuli (such as heat, light, and pH). The resulting polymer crosslinked network can undergo topological rearrangement under external influences, thus exhibiting characteristics such as plasticity, self-healing, and stimulus responsiveness. Among these, associative dynamic covalent bonds were first applied to vitrimer-like polymers by Leibler et al. in 2011 and have seen rapid development in recent years. Vitrimers are crosslinked networks constructed from associative dynamic covalent bonds, exhibiting processing properties similar to glass. Imino bonds (C=N) are a type of associative dynamic covalent bond, a class of dynamic reversible covalent bonds formed by the reaction of carbonyl-containing compounds (aldehydes or ketones) with amino-containing compounds (primary amines, hydrazines, and hydroxylamines), characterized by mild reaction conditions and fast reaction rates.

[0005] J Polym Sci (Part A: Polym Chem, 2017, 55(12): 2011-2018) discloses a method for preparing dynamically imine-crosslinked polybutadiene elastomers by crosslinking amine-functionalized polybutadiene with aldehydes. This literature utilizes an imine exchange reaction between aldehyde and amine groups to prepare Vitrimer-reversibly crosslinked cis-butadiene rubber. The drawback of this technique, or its relative deficiency compared to the present invention, is that both cis-butadiene rubber and styrene-butadiene rubber side groups have a large number of double bonds available for reaction, making system implementation easy, but this method is not applicable to polypropylene systems (polypropylene molecules do not contain double bonds).

[0006] Chinese patent document CN111662561A discloses a method for preparing a flame-retardant, reprocessable wood-plastic composite material. In this document, organic aldehydes are first dispersed in ethyl acetate, then a certain amount of ammonium polyphosphate is added, followed by ethyl acetate containing amines, to obtain a yellow suspension. This suspension is then dried to obtain a solid powder of ammonium polyphosphate containing imine dynamic covalent bonds. The ammonium polyphosphate powder containing imine dynamic covalent bonds is then initially mixed with plant fibers and plastics, dried, plasticized, molded, and cooled to produce a flame-retardant, reprocessable wood-plastic composite material. The method in this document simultaneously imparts flame retardancy, toughness, and processability to the wood-plastic composite material by introducing imine dynamic covalent bonds; however, the imine dynamic bonds are between small molecules and do not form a large molecular cross-linked network structure.

[0007] Therefore, while improving the flexural modulus and low-temperature resistance of glass fiber reinforced polypropylene composites, how to improve the notched impact strength is a technical problem that urgently needs to be solved. Summary of the Invention

[0008] The purpose of this invention is to solve the problem of poor notched impact strength in glass fiber reinforced polypropylene composites in the prior art, and to provide a glass fiber reinforced polypropylene composite material and its preparation method, which improves the flexural modulus and low temperature resistance while improving the notched impact strength to enhance the overall performance of the glass fiber reinforced polypropylene composite material.

[0009] To achieve the above objectives, the present invention provides a glass fiber reinforced polypropylene composite material, wherein, by weight percentage, the glass fiber reinforced polypropylene composite material comprises the following raw materials: 45.5%-75% modified copolymer polypropylene, 10%-26% glass fiber, 3%-9% toughening agent, 3.5%-12.0% coupling agent, 4%-7% compatibilizer, and 0.4%-0.6% stabilizer;

[0010] The coupling agent contains at least two primary amines, and the modified copolymer polypropylene contains aldehyde groups.

[0011] Optionally, the modified copolymer polypropylene contains aldehyde groups in its side chains.

[0012] Optionally, the modified copolymer polypropylene is a product obtained by free radical polymerization of copolymer polypropylene and a modifier; the modifier is selected from at least one of the compounds shown in Formula III.

[0013] CH2=CH-R 3 -CHO

[0014] III

[0015] Among them, R 3 Selected from C1-C12 straight-chain or branched alkylene groups, C3-C8 cycloalkylene groups, and unsubstituted or substituted C6-C12 arylene or heteroarylene groups; preferably, R 3 Selected from C1-C3 straight-chain alkylene groups, or unsubstituted C6-C12 arylene groups; more preferably, R 3 Selected from methylene, -CH2CH2-, -CH2CH2CH2- or phenylene;

[0016] R 3 In the definition of a group, "substituted" means that at least one H on the group is substituted by a straight-chain or branched alkyl or alkoxy group selected from C1-C4.

[0017] Optionally, the modified copolymer polypropylene comprises the following raw materials by weight percentage:

[0018] The copolymer contains 81%-94% polypropylene, 0.5%-1.5% initiator, and 5%-18% modifier.

[0019] Optionally, the melt flow rate of the copolymer polypropylene is 60-150 g / 10 min.

[0020] Optionally, the coupling agent is at least one of the structures shown in Formula I and / or Formula II.

[0021]

[0022] Among them, R 1 Selected from C1-C12 straight-chain or branched alkylene groups, C3-C8 cycloalkylene groups, and unsubstituted or substituted C6-C12 arylene or heteroarylene groups; preferably, R 1 Selected from C2-C3 straight-chain alkylene groups; more preferably, R 1 Selected from -CH2CH2- or -CH2CH2CH2-;

[0023] R 2Selected from C1-C6 straight-chain or branched alkylene groups, C3-C6 cycloalkylene groups, unsubstituted or substituted C6-C12 arylene or heteroarylene groups; preferably, R 2 Selected from C2-C3 straight-chain alkylene groups; more preferably, R 2 Selected from -CH2CH2- or -CH2CH2CH2-;

[0024] R 1 and R 2 In the definition of a group, "substituted" means that at least one H on the group is substituted by a straight-chain or branched alkyl or alkoxy group selected from C1-C4.

[0025] Optionally, the glass fiber is selected from at least one of short-wavelength glass fiber, long glass fiber, and continuous glass fiber; preferably, the glass fiber is long glass fiber; more preferably, the length of the long glass fiber is 10-25 mm.

[0026] The toughening agent is ethylene-octene copolymer (POE), and the melt flow rate (190℃, 2.16Kg) of the ethylene-octene copolymer is 0.5-30g / 10min;

[0027] The compatibilizer is maleic anhydride-grafted polypropylene.

[0028] The stabilizer is at least one of hindered phenolic antioxidants and phosphorous antioxidants; preferably, the stabilizer is a mixture of hindered phenolic antioxidants and phosphorous antioxidants; more preferably, the mass ratio of the hindered phenolic antioxidant to the phosphorous antioxidant in the stabilizer is (1-5):1; even more preferably, the mass ratio of the hindered phenolic antioxidant to the phosphorous antioxidant in the stabilizer is (1-3):1; even more preferably, the mass ratio of the hindered phenolic antioxidant to the phosphorous antioxidant in the stabilizer is 2:1.

[0029] Specifically, the hindered phenolic antioxidants include, but are not limited to, mono-hindered phenols and poly-hindered phenols, such as butylated hydroxytoluene (BHT), antioxidant 1024, antioxidant 3114, antioxidant 1010, and antioxidant 1330; the phosphite antioxidants, i.e., phosphite ester antioxidants, include, but are not limited to, phenol-free phosphite ester antioxidants, low-phenolic phosphite ester antioxidants, and phenolic phosphite ester antioxidants, such as antioxidant 168.

[0030] Optionally, the glass fiber reinforced polypropylene composite material further contains at least one of a colorant, a light stabilizer, and a lubricant, wherein the total content of the colorant, light stabilizer, and lubricant in the glass fiber reinforced polypropylene composite material does not exceed 2% by mass percentage.

[0031] Optionally, the colorant, light stabilizer, and lubricant may be selected from any commonly used in the art, such as the lubricant being selected from at least one of stearate, polyolefin wax, ethylene bis-stearamide, and pentaerythritol stearate; the light stabilizer being at least one of hindered amine light stabilizers, triazine light stabilizers, and benzotriazole light stabilizers; and the colorant being selected from inorganic pigments and / or organic pigments.

[0032] The invention also provides a method for preparing the above-mentioned glass fiber reinforced polypropylene composite material, comprising the following steps:

[0033] Modified copolymer polypropylene, toughening agent, coupling agent, compatibilizer and stabilizer are mixed, and the resulting mixture is further mixed with glass fiber and then extruded at 190-230℃ to obtain the glass fiber reinforced polypropylene composite material.

[0034] Optionally, the length-to-diameter ratio of the extruder in the extrusion step is (40-60):1.

[0035] Optionally, the modified copolymer polypropylene, toughening agent, coupling agent, compatibilizer and stabilizer are mixed by dry mixing, with a mixing time of 3-5 minutes.

[0036] Optionally, the preparation method of the modified copolymer polypropylene includes the following steps:

[0037] The modified copolymer polypropylene is obtained by mixing the copolymer polypropylene, initiator and modifier and extruding at 180-210°C; the modifier is selected from at least one of the compounds shown in Formula III above.

[0038] Optionally, the mixing time of the copolymer polypropylene, initiator and modifier is 2-10 min.

[0039] The modifier's role is to introduce (graft) the aldehyde group from the modifier onto the side chain of the copolymer polypropylene.

[0040] Optionally, the initiator is at least one of conventional initiators such as azobisisobutyronitrile and dicumyl peroxide.

[0041] Optionally, the preparation method of the glass fiber reinforced polypropylene composite material further includes the step of mixing at least one of the colorant, light stabilizer and lubricant with the modified copolymer polypropylene, toughening agent, coupling agent, compatibilizer and stabilizer.

[0042] Optionally, in the preparation method of the glass fiber reinforced polypropylene composite material and the preparation process of the modified copolymer polypropylene, the mixing step can use any existing conventional mixing device, such as an open mill or a mixer; the extrusion step can use any existing conventional basic device, such as a single-screw extruder or a twin-screw extruder.

[0043] Compared with existing technologies, the present invention has the following advantages:

[0044] 1. The glass fiber reinforced polypropylene composite material provided by this invention utilizes a coupling agent containing at least two primary amines and a modified copolymer polypropylene containing aldehyde groups to form a reversibly cross-linked macromolecular network structure. Glass fibers, compatibilizers, stabilizers, and toughening agents fill the voids in the macromolecular network structure. The resulting glass fiber reinforced polypropylene composite material significantly improves notched impact strength while enhancing flexural modulus and low-temperature resistance, exhibiting high flowability and high toughness. The glass fiber reinforced polypropylene material provided by this invention possesses excellent comprehensive properties.

[0045] 2. The preparation method of glass fiber reinforced polypropylene composite material provided by the present invention involves mixing and extrusion, which allows the aldehyde groups in the modified copolymer polypropylene to react with the amino groups in the coupling agent, generating uniformly distributed dynamic reversible covalent bonds (C=N) on the side chains of the copolymer polypropylene. Combined with other components, the composite material crosslinks at low temperatures, thereby significantly improving its toughness and low-temperature resistance. At high temperatures, the crosslinking bonds rearrange their network structure through thermally activated associative exchange reactions. The formation of new bonds and the breaking of old bonds occur simultaneously, thus endowing the composite material with thermoplasticity. This allows the composite material to crosslink during use and decrosslink during processing, and the components have good interfacial compatibility. This solves the problem of reduced notched impact strength when glass fiber reinforced PP composite materials significantly improve product strength (i.e., rigidity) and flexural modulus.

[0046] 3. The glass fiber reinforced polypropylene composite material prepared by the method of the present invention has a reversible crosslinking in the macromolecules. Therefore, the composite material can be repeatedly processed and recycled from waste parts. In the process of repeated processing, only an appropriate amount of stabilizer needs to be added to the existing glass fiber reinforced polypropylene composite material, dry-mixed, extruded and granulated. The stabilizer can be any one or a mixture of several commonly used in the industry. The amount of stabilizer added, the dry mixing time and the extrusion temperature can be adjusted according to the actual situation. For example, the mass of the stabilizer added is 0.5wt%-1.5wt% of the mass of the glass fiber reinforced polypropylene composite material, the dry mixing time can be selected as 2-5 min, and the extrusion temperature can be selected as 180-210℃. Detailed Implementation

[0047] The present invention will now be described in detail through embodiments. It should be noted that the following embodiments are only for further illustration of the present invention and should not be construed as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above description.

[0048] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0049] Any commercially available toughening agent, coupling agent containing at least two primary amines, compatibilizer, and stabilizer can satisfy the implementation of the technical solution of this invention. For ease of comparison, unless otherwise specified, the toughening agent used in the following examples and comparative examples is Dow's POE8150, the coupling agent is ethylenediamine, the compatibilizer is maleic anhydride-grafted polypropylene (grafting rate of 0.8 wt%), and the stabilizer is a mixture of hindered phenolic antioxidant 1010 and phosphite antioxidant 168 (wherein the mass ratio of hindered phenolic antioxidant 1010 to phosphite antioxidant 168 is 2:1).

[0050] The equipment used in the following embodiments and comparative examples is as follows:

[0051] Type 35 twin-screw extruder: Benelux Nanjing Machinery Co., Ltd., with a length-to-diameter ratio of 45:1 (the choice of length-to-diameter ratio does not affect the effect of the technical solution of this invention; this value is adopted for ease of comparison).

[0052] Injection molding machine: Liuzhou Injection Molding Machinery Factory UN-100, which injects standard samples into the sample.

[0053] The relevant performance data of the glass fiber reinforced polypropylene composite materials prepared in each embodiment and comparative example in Table 1 below were obtained according to the following test methods:

[0054] Melt flow rate (MFR): determined according to GB / T 3682-2000, 230℃, 2.16kg load.

[0055] Impact strength of simply supported beams: determined according to GB / T1043.1-2008

[0056] Flexural modulus: determined according to GB / T 9341-2008.

[0057] Example 1

[0058] This embodiment provides a glass fiber reinforced polypropylene composite granule, the preparation method of which is as follows:

[0059] 1) Preparation of modified copolymer polypropylene:

[0060] The modified copolymer polypropylene (grade EP100N, melt flow rate 100g / 10min, produced by Lanzhou Petrochemical Company of China National Petroleum Corporation), initiator (azobisisobutyronitrile) and modifier (4-vinylbenzaldehyde) were mixed for 5min and then extruded at 180℃ to obtain the modified copolymer polypropylene; the grafting rate of the modifier vinylbenzaldehyde in the modified copolymer polypropylene was 4.3wt%.

[0061] The contents of each raw material in the above modified copolymer polypropylene, by mass percentage, are as follows:

[0062] The copolymer contains 93% polypropylene, 1% initiator, and 6% modifier.

[0063] 2) Weigh the modified copolymer polypropylene and other raw materials obtained in step 1) according to the following mass percentages:

[0064] The composition includes 66% modified copolymer polypropylene, 20% glass fiber (15mm in length), 6% toughening agent, 3.6% coupling agent, 4% compatibilizer, and 0.4% stabilizer.

[0065] 3) The weighed modified copolymer polypropylene, toughening agent, coupling agent, compatibilizer and stabilizer are dry mixed in a high-speed mixer for 3 minutes and then added to the hopper of a twin-screw extruder. Then, glass fiber is added to the extruder through the side feed port. The two parts are kneaded in the twin-screw extruder and then extruded and cold-cut into granules at 200°C to obtain glass fiber reinforced polypropylene composite granules. The performance data of the granules are shown in Table 1.

[0066] Comparative Example 1

[0067] This comparative example provides a glass fiber reinforced polypropylene composite granule, the preparation method of which is as follows:

[0068] 1) Weigh each raw material according to the following mass percentages:

[0069] The composition of the copolymer polypropylene (grade EP100N, melt flow rate 100g / 10min, produced by Lanzhou Petrochemical Company of China National Petroleum Corporation) is 68.8%, glass fiber (length 15mm) is 20.8%, toughening agent is 6%, compatibilizer is 4%, and stabilizer is 0.4%.

[0070] 2) The weighed copolymer polypropylene, toughening agent, compatibilizer and stabilizer are dry mixed in a high-speed mixer for 3 minutes and then added to the hopper of a twin-screw extruder. Then the glass fiber is added to the extruder through the side feed port. The two materials are kneaded in the twin-screw extruder and then extruded and cold-cut into granules at 200°C to obtain glass fiber reinforced polypropylene composite granules. The performance data of the granules are shown in Table 1.

[0071] Comparative Example 2

[0072] This comparative example provides a glass fiber reinforced polypropylene composite granule, the preparation method of which is as follows:

[0073] 1) Preparation of modified copolymer polypropylene:

[0074] The modified copolymer polypropylene (grade EP100N, melt flow rate 100g / 10min, produced by Lanzhou Petrochemical Company of China National Petroleum Corporation), initiator (azobisisobutyronitrile) and modifier (4-vinylbenzaldehyde) were mixed for 5 min and then extruded at 180℃ to obtain the modified copolymer polypropylene; the grafting rate of the modifier vinylbenzaldehyde in the modified copolymer polypropylene was 4.3wt%.

[0075] The contents of each raw material in the above modified copolymer polypropylene, by mass percentage, are as follows:

[0076] The copolymer contains 93% polypropylene, 1% initiator, and 6% modifier.

[0077] 2) Weigh the modified copolymer polypropylene and other raw materials obtained in step 1) according to the following mass percentages:

[0078] The modified copolymer polypropylene is 68.8%, glass fiber (15mm in length) is 20.8%, toughening agent is 6%, compatibilizer is 4%, and stabilizer is 0.4%.

[0079] 3) The weighed modified copolymer polypropylene, toughening agent, compatibilizer and stabilizer are dry mixed in a high-speed mixer for 3 minutes and then added to the hopper of a twin-screw extruder. Then the glass fiber is added to the extruder through the side feed port. The two parts are kneaded in the twin-screw extruder and then extruded and cold-cut into granules at 200°C to obtain glass fiber reinforced polypropylene composite granules. The performance data of the granules are shown in Table 1.

[0080] Comparative Example 3

[0081] This comparative example provides a glass fiber reinforced polypropylene composite granule, the preparation method of which is as follows:

[0082] 1) Weigh each raw material according to the following mass percentages:

[0083] The composition consists of 66% copolymer polypropylene (grade EP100N, melt flow rate 100g / 10min, produced by Lanzhou Petrochemical Company of China National Petroleum Corporation), 20% glass fiber (length 15mm), 6% toughening agent, 3.6% coupling agent, 4% compatibilizer and 0.4% stabilizer.

[0084] 2) The weighed copolymer polypropylene, toughening agent, coupling agent, compatibilizer and stabilizer are dry mixed in a high-speed mixer for 3 minutes and then added to the hopper of a twin-screw extruder. Then the glass fiber is added to the extruder through the side feed port. The two parts are kneaded in the twin-screw extruder and then extruded and cold-cut into granules at 200°C to obtain glass fiber reinforced polypropylene composite granules. The performance data of the granules are shown in Table 1.

[0085] Comparative Example 4

[0086] This comparative example provides a glass fiber reinforced polypropylene composite granule, the preparation method of which is as follows:

[0087] 1) Preparation of modified copolymer polypropylene:

[0088] The modified copolymer polypropylene (grade EP100N, melt flow rate 100g / 10min, produced by Lanzhou Petrochemical Company of China National Petroleum Corporation), initiator (azobisisobutyronitrile) and modifier (4-vinylbenzaldehyde) were mixed for 9min and then extruded at 180℃ to obtain the modified copolymer polypropylene; the grafting rate of the modifier vinylbenzaldehyde in the modified copolymer polypropylene was 4.3wt%.

[0089] The contents of each raw material in the above modified copolymer polypropylene, by mass percentage, are as follows:

[0090] The copolymer contains 93% polypropylene, 1% initiator, and 6% modifier.

[0091] 2) Weigh the modified copolymer polypropylene and other raw materials obtained in step 1) according to the following mass percentages:

[0092] The mixture contains 66% modified copolymer polypropylene, 20% glass fiber (15mm in length), 6% toughening agent, 3.6% coupling agent (ethylamine is used in this comparative example), 4% compatibilizer, and 0.4% stabilizer.

[0093] 3) The weighed modified copolymer polypropylene, toughening agent, coupling agent, compatibilizer and stabilizer are dry mixed in a high-speed mixer for 3 minutes and then added to the hopper of a twin-screw extruder. Then, glass fiber is added to the extruder through the side feed port. The two parts are kneaded in the twin-screw extruder and then extruded and cold-cut into granules at 200°C to obtain glass fiber reinforced polypropylene composite granules. The performance data of the granules are shown in Table 1.

[0094] Comparative Example 5

[0095] This comparative example provides a glass fiber reinforced polypropylene composite granule, the preparation method of which is as follows:

[0096] 1) Weigh each raw material according to the following mass percentages:

[0097] The composition is: 62% copolymer polypropylene (grade EP100N, melt flow rate 100g / 10min, produced by Lanzhou Petrochemical Company of China National Petroleum Corporation), 20% glass fiber (length 15mm), 6% toughening agent, 3.6% coupling agent, 4% compatibilizer and 0.4% stabilizer, and 4% modifier (4-vinylbenzaldehyde).

[0098] 2) The weighed copolymer polypropylene, toughening agent, coupling agent, compatibilizer, modifier and stabilizer are dry mixed in a high-speed mixer for 3 minutes and then added to the hopper of a twin-screw extruder. Then the glass fiber is added to the extruder through the side feed port. The two parts are kneaded in the twin-screw extruder and then extruded and cold-cut into granules at 200°C to obtain glass fiber reinforced polypropylene composite granules. The performance data of the granules are shown in Table 1.

[0099] Example 2

[0100] This embodiment provides a glass fiber reinforced polypropylene composite granule, the preparation method of which is as follows:

[0101] 1) Preparation of modified copolymer polypropylene:

[0102] The modified copolymer polypropylene (grade EP150N, melt flow rate 150g / 10min, produced by Lanzhou Petrochemical Company of China National Petroleum Corporation), initiator (azobisisobutyronitrile) and modifier (4-vinylbenzaldehyde) were mixed for 4min and then extruded at 210℃ to obtain the modified copolymer polypropylene; the grafting rate of the modifier vinylbenzaldehyde in the modified copolymer polypropylene was 5.4wt%.

[0103] The contents of each raw material in the above modified copolymer polypropylene, by mass percentage, are as follows:

[0104] The copolymer contains 89.4% polypropylene, 1.1% initiator, and 9.5% modifier.

[0105] 2) Weigh the modified copolymer polypropylene and other raw materials obtained in step 1) according to the following mass percentages:

[0106] The composition includes 75% modified copolymer polypropylene, 11% glass fiber (15mm in length), 3% toughening agent, 4.4% coupling agent, 6% compatibilizer, and 0.6% stabilizer.

[0107] The weighed modified copolymer polypropylene, toughening agent, coupling agent, compatibilizer and stabilizer were dry-mixed in a high-speed mixer for 2 minutes and then added to the hopper of a twin-screw extruder. Then, glass fiber was added to the extruder through the side feed port. The two materials were kneaded together in the twin-screw extruder and then extruded at 190°C and cold-cut into granules to obtain glass fiber reinforced polypropylene composite granules. The performance data of the granules are shown in Table 1.

[0108] Example 3

[0109] This embodiment provides a glass fiber reinforced polypropylene composite granule, the preparation method of which is as follows:

[0110] 1) Preparation of modified copolymer polypropylene:

[0111] The modified copolymer polypropylene (grade EP508N, melt flow rate 65 g / 10 min, produced by Lanzhou Petrochemical Company of China National Petroleum Corporation), initiator (dicumyl peroxide) and modifier (4-vinylbenzaldehyde) were mixed for 10 min and then extruded at 190 °C to obtain the modified copolymer polypropylene; the grafting rate of the modifier vinylbenzaldehyde in the modified copolymer polypropylene was 8.7 wt%.

[0112] The contents of each raw material in the above modified copolymer polypropylene, by mass percentage, are as follows:

[0113] The copolymer contains 81.3% polypropylene, 1.5% initiator, and 17.2% modifier.

[0114] 2) Weigh the modified copolymer polypropylene and other raw materials obtained in step 1) according to the following mass percentages:

[0115] Modified copolymer polypropylene 45.6%, glass fiber (20mm in length) 26%, toughening agent 9%, coupling agent 12%, compatibilizer 7% and stabilizer 0.4%;

[0116] The weighed modified copolymer polypropylene, toughening agent, coupling agent, compatibilizer and stabilizer were dry-mixed in a high-speed mixer for 4 minutes and then added to the hopper of a twin-screw extruder. Glass fiber was then added to the extruder through the side feed port. The two materials were kneaded together in the twin-screw extruder and then extruded and cold-cut into granules at 210°C to obtain glass fiber reinforced polypropylene composite granules. The performance data of the granules are shown in Table 1.

[0117] Example 4

[0118] This embodiment provides a glass fiber reinforced polypropylene composite granule, the preparation method of which is as follows:

[0119] 1) Preparation of modified copolymer polypropylene:

[0120] The modified copolymer polypropylene (grade EP508N, melt flow rate 65g / 10min, produced by Lanzhou Petrochemical Company of China National Petroleum Corporation), initiator (dicumyl peroxide) and modifier (4-vinylbenzaldehyde) were mixed for 7min and then extruded at 200℃ to obtain the modified copolymer polypropylene; the grafting rate of the modifier vinylbenzaldehyde in the modified copolymer polypropylene was 6.8wt%.

[0121] The contents of each raw material in the above modified copolymer polypropylene, by mass percentage, are as follows:

[0122] The copolymer contains 85.9% polypropylene, 0.6% initiator, and 13.5% modifier.

[0123] 2) Weigh the modified copolymer polypropylene and other raw materials obtained in step 1) according to the following mass percentages:

[0124] The modified copolymer polypropylene is 63.6%, glass fiber (20mm in length) is 15%, toughening agent is 6%, coupling agent is 8.5%, compatibilizer is 6.3%, and stabilizer is 0.6%.

[0125] The weighed modified copolymer polypropylene, toughening agent, coupling agent, compatibilizer and stabilizer were dry-mixed in a high-speed mixer for 3 minutes and then added to the hopper of a twin-screw extruder. Glass fiber was then added to the extruder through the side feed port. The two materials were kneaded together in the twin-screw extruder and then extruded and cold-cut into granules at 230°C to obtain glass fiber reinforced polypropylene composite granules. The performance data of the granules are shown in Table 1.

[0126] Example 5

[0127] This embodiment provides a method for repeated processing of glass fiber reinforced polypropylene composite granules, the specific steps of which are as follows:

[0128] Weigh a certain amount of glass fiber reinforced polypropylene composite material granules obtained in Example 4 (denoted as composite material A), and add a stabilizer (the stabilizer is a mixture of hindered phenolic antioxidant 1010 and phosphite antioxidant 168, with a mass ratio of hindered phenolic antioxidant 1010 to phosphite antioxidant 168 of 2:1). Then, dry mix in a high-speed mixer for 2 minutes, and then add it to a twin-screw extruder for melt extrusion at 190°C, followed by cold cutting and granulation to obtain glass fiber reinforced polypropylene composite material granules. The performance data of the granules are shown in Table 1.

[0129] The amount of stabilizer added is 0.5 wt% of the mass of particle A in the composite material.

[0130] Example 6

[0131] This embodiment provides a method for repeated processing of glass fiber reinforced polypropylene composite granules, the specific steps of which are as follows:

[0132] Weigh a certain amount of the glass fiber reinforced polypropylene composite material granules obtained in Example 5 (denoted as composite material B), and add a stabilizer (the stabilizer is a mixture of hindered phenolic antioxidant 1010 and phosphite antioxidant 168, with a mass ratio of hindered phenolic antioxidant 1010 to phosphite antioxidant 168 of 2:1). Then, dry mix in a high-speed mixer for 3 minutes, and then add it to a twin-screw extruder for melt extrusion at 190°C, followed by cold cutting and granulation to obtain the glass fiber reinforced polypropylene composite material granules. The performance data of the granules are shown in Table 1.

[0133] The amount of stabilizer added is 1 wt% of the mass of particle B in the composite material.

[0134] Table 1 Performance Data

[0135]

[0136] Data Analysis:

[0137] Comparative Example 1: The copolymer polypropylene was not grafted with a modifier (aldehyde compound), and no coupling agent was added to the formulation. Comparative Example 2: The copolymer polypropylene was grafted with a modifier (aldehyde compound), but no coupling agent was added to the formulation. Comparative Example 3: The copolymer polypropylene was not grafted with a modifier (aldehyde compound), but a coupling agent was added to the formulation. In Comparative Example 4, ethylamine was used instead of ethylenediamine as the coupling agent. Comparative Example 5: The copolymer polypropylene was not grafted with a modifier (aldehyde compound), but methacrolein was added to the modified formulation; otherwise, it was the same as in Example 1.

[0138] In all embodiments, modified copolymer polypropylene was used. The aldehyde groups grafted onto the side chains of the copolymer polypropylene reacted with the amino groups on the coupling agent to form a composite material with reversible crosslinking function based on imine bonds (Vitrimer reaction). Comparing Example 1 with Comparative Examples 1, 2, and 3, it can be seen that the notched impact strength and flexural modulus of the glass fiber reinforced polypropylene composite material provided by this invention are significantly improved, and it also exhibits excellent rigidity, toughness, and low-temperature resistance. In Examples 2-4, by adjusting the composition and content of each raw material in the formulation, the obtained glass fiber reinforced polypropylene composite material maintains the high strength of general glass fiber reinforced PP, while its notched impact strength, flexural modulus, and toughness can be adjusted within a wide range to meet the performance requirements of glass fiber reinforced PP in different fields. Compared with Example 1, the mechanical properties of the composite material obtained by replacing the coupling agent with mono-primary amine ethylamine in Comparative Example 4 are not significantly improved. This may be because the mono-primary amine groups in Comparative Example 4 failed to form an effective macromolecular network crosslinking structure. Compared with Comparative Example 1, the composite material prepared in Comparative Example 5 has comparable performance to the composite material without the addition of modifiers and coupling agents. This may be because only some small molecules are cross-linked in the system, which has almost no effect on the overall performance of the composite material.

[0139] The glass fiber reinforced polypropylene composite material provided by this invention has high flowability and high toughness, and its performance can still be well maintained after repeated processing. Specifically, as can be seen from the comparison between Examples 4-6, Example 5 is obtained by adding a small amount of antioxidant to Example 4 and then processing it again, and Example 6 is obtained by adding a small amount of antioxidant to Example 5 and then processing it further. After repeated processing, the performance of the material is basically maintained without reduction. The maintenance of this excellent effect is due to the fact that the crosslinking in the composite material is thermally reversible crosslinking. The crosslinking structure can still be stably restored after repeated processing, which is completely different from the permanent crosslinking network formed by traditional crosslinking technology, thus giving the crosslinked polymer excellent thermoplastic properties.

[0140] In summary, the glass fiber reinforced polypropylene composite material provided by this invention is a novel composite material with reversible crosslinking function. During melt processing, it has the significant characteristics of decrosslinking at high temperature (during processing) and easy processing, while forming crosslinks at low temperature (after molding) and high performance.

[0141] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the claims of the present invention.

Claims

1. A glass fiber reinforced polypropylene composite material, characterized in that, By weight percentage, the glass fiber reinforced polypropylene composite material comprises the following raw materials: 45.5%-75% modified copolymer polypropylene, 10%-26% glass fiber, 3%-9% toughening agent, 3.5%-12.0% coupling agent, 4%-7% compatibilizer, and 0.4%-0.6% stabilizer; The coupling agent contains at least two primary amines, and the modified copolymer polypropylene contains aldehyde groups. The modified copolymer polypropylene is the product obtained by free radical polymerization of copolymer polypropylene and a modifier; the modifier is selected from at least one of the compounds shown in Formula III; Ⅲ Among them, R 3 Selected from C1-C12 straight-chain or branched alkylene groups, C3-C8 cycloalkylene groups, and unsubstituted or substituted C6-C12 arylene or heteroarylene groups; The coupling agent is at least one of the structures shown in Formula I and / or Formula II. Among them, R 1 Selected from C1-C12 straight-chain or branched alkylene groups, C3-C8 cycloalkylene groups, unsubstituted or substituted C6-C12 arylene or heteroarylene groups, R 2 Selected from C1-C6 straight-chain or branched alkylene groups, C3-C6 cycloalkylene groups, and unsubstituted or substituted C6-C12 arylene or heteroarylene groups.

2. The glass fiber reinforced polypropylene composite material as described in claim 1, characterized in that, R 3 Selected from C1-C3 straight-chain alkylene groups, or unsubstituted C6-C12 arylene groups.

3. The glass fiber reinforced polypropylene composite material as described in claim 1, characterized in that, The modified copolymer polypropylene comprises the following raw materials by weight percentage: The copolymer contains 81%-94% polypropylene, 0.5%-1.5% initiator, and 5%-18% modifier.

4. The glass fiber reinforced polypropylene composite material as described in claim 1, characterized in that, The melt flow rate of the copolymerized polypropylene is 60-150 g / 10 min.

5. The glass fiber reinforced polypropylene composite material as described in claim 1, characterized in that, R 1 Selected from C2-C3 straight-chain alkylene groups.

6. The glass fiber reinforced polypropylene composite material as described in claim 1, characterized in that, The glass fiber is selected from at least one of short-wave glass fiber, long glass fiber, and continuous glass fiber; The toughening agent is an ethylene-octene copolymer, and the melt flow rate of the ethylene-octene copolymer is 0.5-30 g / 10 min; The compatibilizer is maleic anhydride-grafted polypropylene. The stabilizer is at least one of hindered phenolic antioxidants and phosphorous antioxidants.

7. The glass fiber reinforced polypropylene composite material as described in claim 2, characterized in that, R 3 Selected from methylene, -CH2CH2-, -CH2CH2CH2- or phenylene.

8. The glass fiber reinforced polypropylene composite material as described in claim 5, characterized in that, R 1 Selected from -CH2CH2- or -CH2CH2CH2-.

9. The glass fiber reinforced polypropylene composite material as described in claim 1, characterized in that, R 2 Selected from C2-C3 straight-chain alkylene groups.

10. The glass fiber reinforced polypropylene composite material as described in claim 9, characterized in that... R 2 Selected from -CH2CH2- or -CH2CH2CH2-.

11. The glass fiber reinforced polypropylene composite material as described in claim 6, characterized in that, The glass fiber is a long glass fiber.

12. The glass fiber reinforced polypropylene composite material as described in claim 6, characterized in that, The length of the long glass fiber is 10-25mm.

13. The glass fiber reinforced polypropylene composite material as described in claim 6, characterized in that, The stabilizer is a mixture of hindered phenolic antioxidants and phosphorous antioxidants.

14. The glass fiber reinforced polypropylene composite material according to any one of claims 1-13, characterized in that, The glass fiber reinforced polypropylene composite material also contains at least one of a colorant, a light stabilizer, and a lubricant, and the total content of the colorant, light stabilizer, and lubricant in the glass fiber reinforced polypropylene composite material does not exceed 2% by mass percentage.

15. A method for preparing the glass fiber reinforced polypropylene composite material according to any one of claims 1-13, characterized in that, Includes the following steps: Modified copolymer polypropylene, toughening agent, coupling agent, compatibilizer and stabilizer are mixed, and the resulting mixture is further mixed with glass fiber and then extruded at 190-230℃ to obtain the glass fiber reinforced polypropylene composite material.

16. The method for preparing the glass fiber reinforced polypropylene composite material according to claim 3, characterized in that, Modified copolymer polypropylene, toughening agent, coupling agent, compatibilizer and stabilizer are mixed, and the resulting mixture is further mixed with glass fiber and then extruded at 190-230℃ to obtain the glass fiber reinforced polypropylene composite material. The preparation method of the modified copolymer polypropylene includes the following steps: The modified copolymer polypropylene is obtained by mixing the copolymer polypropylene, initiator and modifier and extruding at 180-210°C.

17. The method for preparing the glass fiber reinforced polypropylene composite material according to claim 14, characterized in that, Includes the following steps: Modified copolymer polypropylene, toughening agent, coupling agent, compatibilizer and stabilizer are mixed, and the resulting mixture is further mixed with glass fiber and then extruded at 190-230℃ to obtain the glass fiber reinforced polypropylene composite material. It also includes the step of mixing at least one of the colorant, light stabilizer and lubricant with the modified copolymer polypropylene, toughening agent, coupling agent, compatibilizer and stabilizer.

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