High-rigidity and high-toughness seat PP composite material and preparation method thereof

Abstract

The invention relates to the technical field of high polymer materials, in particular to a high-rigidity and high-toughness seat PP composite material and a preparation method thereof. The polypropylene composite material is prepared from the following components in parts by weight: 30 to 50 parts of polypropylene, 10 to 25 parts of high-density polyethylene, 3 to 6 parts of linear low-density polyethylene graft, 10 to 20 parts of inorganic filler, 5 to 10 parts of alkali-free glass fiber, 0.3 to 0.6 part of coupling agent, 1 to 2 parts of macromolecular dispersant and 0.2 to 0.5 part of antioxidant, wherein the linear low-density polyethylene graft is prepared by mixing linear low-density polyethylene, 3-(vinyloxy) propyl-1-amine and dielectric acid according to the mass ratio of 10: (0.1-0.5): (2-3). Under the joint synergistic effect of the linear low-density polyethylene graft, the medium-alkali glass fiber and the composite inorganic filler, the prepared polypropylene composite material has high rigidity and high toughness, and the requirements that the prepared protective seat has excellent rigidity, also has good rebound resilience and is not prone to deformation are met.

Description

Technical Field

[0001] The invention relates to the technical field of polymer materials, in particular to a high-rigidity and high-toughness seat PP composite material and a preparation method thereof. Background Art

[0002] Polypropylene (PP) is a thermoplastic resin made by propylene polymerization. It is non-toxic, odorless, has low density, and its strength, stiffness, hardness and heat resistance are superior to those of low-pressure polyethylene. It can be used at around 100°C. In addition, polypropylene has good dielectric properties and high-frequency insulation, and is not affected by humidity. These characteristics make polypropylene have broad application prospects in seat manufacturing. For example, polypropylene is a common raw material for preparing seats. When preparing a protective seat, it is necessary to have a certain stiffness, stiffness and resilience, and the product must have the dual characteristics of resistance to falling fracture and resistance to gravity fracture. Therefore, the PP composite material must have high rigidity, strength and resilience. However, pure polypropylene still has shortcomings in stiffness and toughness. In view of this, we propose a high-rigidity and high-toughness seat PP composite material and a preparation method thereof. Summary of the invention

[0003] The object of the present invention is to provide a high-rigidity and high-toughness seat PP composite material and a preparation method thereof, so as to solve the problems raised in the above-mentioned background technology.

[0004] To achieve the above object, on the one hand, the present invention provides a high-rigidity and high-toughness seat PP composite material, comprising the following components: 30-50 parts by weight of polypropylene, 10-25 parts by weight of high-density polyethylene, 3-6 parts by weight of linear low-density polyethylene graft, 10-20 parts by weight of inorganic filler, 5-10 parts by weight of alkali-free glass fiber, 0.3-0.6 parts by weight of coupling agent, 1-2 parts by weight of macromolecular dispersant and 0.2-0.5 parts by weight of antioxidant; The linear low-density polyethylene graft is prepared by mixing linear low-density polyethylene, 3-(vinyloxy)propane-1-amine and dielectric acid in a mass ratio of 10:0.1-0.5:2-3; The macromolecular dispersant is obtained by mixing maleic anhydride grafted polypropylene and 3-(ureaamino)propyltriethoxysilane in a mass ratio of 1:1.5-1.7.

[0005] By reacting the carboxyl group on maleic anhydride grafted polypropylene with the amino group on 3-(ureaamino)propyltriethoxysilane to form an amide bond, the macromolecular dispersant contains both siloxane groups compatible with inorganic materials and carboxyl groups on maleic anhydride and amino groups on 3-(ureaamino)propyltriethoxysilane. At the same time, it is a macromolecule based on polypropylene and has good compatibility with polypropylene composite materials.

[0006] Macromolecular dispersants can better promote the coupling and combination of inorganic fillers, alkali-free glass fibers and polypropylene substrates, improve microscopic compatibility, and make the prepared polypropylene composite materials have high rigidity and high toughness. They have a strong affinity for inorganic fillers, which enables them to be fully activated and modified, destroying and preventing the agglomeration of inorganic substances, so that they are more evenly dispersed in the polymer, thereby increasing the amount of fillers added, and relying on strong interfacial bonding to achieve the effect of toughening and strengthening. When applied to the processing of polymer composite materials, they can well improve the compatibility of the components of the system, promote plasticization, reduce melt viscosity, improve processing fluidity, and reduce The torque of the processing equipment reduces processing energy consumption, improves production efficiency, and can improve the mechanical properties of the product such as impact strength and elongation at break, while significantly improving the surface gloss of the product; the multi-functional group structure with highly active anchoring groups, through the multi-point adsorption of the "anchor" group, chemical reactions are carried out to modify the surface of the filler particles, achieving complete surface chemical reaction coating, making the filler surface organic, thereby effectively reducing the surface energy of the filler; in addition, the long polymer chains in the product macromolecules have strong affinity and compatibility with the matrix polymer material, which greatly improves the processing performance of the composite material system without affecting the physical properties.

[0007] Preferably, the inorganic filler is one or more combinations of calcium carbonate, talc, mica powder, wollastonite, kaolin, magnesium hydroxide and aluminum hydroxide.

[0008] Preferably, the coupling agent is one or more combinations of γ-aminopropyltriethoxysilane, vinyltrimethoxysilane and diisopropyl bis(dioctylpyrophosphate)titanate.

[0009] Preferably, the antioxidant is one or more combinations of 3,5-di-tert-butyl-4-hydroxyphenylpropionic acid n-octadecyl ester, tris[2,4-di-tert-butylphenyl]phosphite and didodecylthiodipropionate.

[0010] Preferably, the preparation method of the linear low density polyethylene graft is as follows: Put linear low-density polyethylene, 3-(vinyloxy)prop-1-amine and diisopropylbenzene peroxide into a high-speed mixer, mix them evenly at room temperature to ensure that the components are evenly distributed, add the mixed materials into an internal mixer, set the temperature to 160-190°C, the rotation speed to 40-50rpm, and the mixing time to 15-20min. After the mixing is completed, immediately take out the product and quickly cool it to obtain a preliminary modified linear low-density polyethylene; put the preliminary modified linear low-density polyethylene, erucic acid, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, 4-dimethylaminopyridine and triethylamine into the internal mixer again, set the reaction temperature to 150-170°C, keep it for 1-2h, after the reaction is completed, immediately take it out and quickly cool it, and then make the product into pellets to obtain a linear low-density polyethylene graft.

[0011] 3-(vinyloxy)propane-1-amine is used to graft linear low-density polyethylene. The introduced amino group can provide polarity to the linear low-density polyethylene, and the interaction between the linear low-density polyethylene molecules is enhanced by forming hydrogen bonds, thereby improving the impact resistance and elongation at break of the linear low-density polyethylene material, and further improving the impact resistance and elongation at break of the polypropylene composite material. At the same time, the polar characteristics of the amino group can also improve the interaction force between the linear low-density polyethylene and the alkali-free glass fiber and the inorganic filler. The amino group forms hydrogen bonds with the surface of the inorganic filler, thereby improving the compatibility problem between the linear low-density polyethylene and the alkali-free glass fiber and the inorganic filler, and avoiding the problem of incompatibility with the alkali-free glass fiber. However, the force of the hydrogen bond is small, especially under high temperature or stress conditions. In order to further enhance the interaction force with the alkali-free glass fiber, erucic acid is introduced to extend the length of the side chain, and the alkali-free glass fiber is coated by forming a winding coating effect, thereby further enhancing the mechanical properties of the composite material, so that the polypropylene composite material has better elongation at break and rebound characteristics.

[0012] Preferably, the dicumyl peroxide accounts for 0.5-2% of the mass of the linear low-density polyethylene; the molar ratio of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, 4-dimethylaminopyridine, triethylamine and erucic acid is 1-1.5:0.1-0.5:1:1.

[0013] Preferably, the preparation method of the macromolecular dispersant is as follows: The maleic anhydride grafted polypropylene is dissolved in dichloromethane to prepare a 3-8% w / v solution, and 4-dimethylaminopyridine is added to obtain a mixed solution, wherein the amount of dimethylaminopyridine added is 0.1-5% of the mass of the maleic anhydride grafted polypropylene. Under nitrogen protection, 3-(ureaamino)propyltriethoxysilane is added dropwise to the mixed solution while stirring, and the reaction mixture is heated to 60-80°C for 4-6 hours. After the reaction is completed, the solvent is removed by a rotary evaporator to obtain a macromolecular dispersant.

[0014] On the other hand, the present invention provides a method for preparing a high-rigidity and high-toughness seat PP composite material, which is used to prepare the above-mentioned high-rigidity and high-toughness seat PP composite material, comprising the following steps: Add polypropylene, high-density polyethylene and linear low-density polyethylene grafts into a high-speed mixer, then add coupling agent, inorganic filler, macromolecular dispersant and antioxidant, and mix thoroughly. Finally, add alkali-free glass fiber and continue mixing until uniform. Use a twin-screw extruder to melt blend the mixed materials, set the temperature curve, control the shear rate and residence time, and finally extrude the composite material through an injection molding machine to obtain a high-stiffness and high-toughness seat PP composite material.

[0015] Alkali-free glass fiber contains lower sodium oxide and calcium oxide content, which makes it have better hydrolysis resistance and chemical corrosion resistance, especially in humid or acidic environment, it shows better stability. The tensile strength and elastic modulus of alkali-free glass fiber are better than those of ordinary glass fiber and mechanical properties, which can provide stronger reinforcement effect. In addition, alkali-free glass fiber has good heat resistance, can keep its physical and mechanical properties unchanged in a wide temperature range, and has better stability. Protective seats need to have certain rigidity, stiffness and resilience, and the product must have the dual characteristics of resistance to falling and breaking, and resistance to gravity breaking, so that the polypropylene composite material must have high rigidity, strength, resilience, and high toughness and elongation at break. However, although general glass fiber reinforced polypropylene can improve the mechanical properties of the seat to a certain extent, its elongation at break is low, so that the obtained seat is easy to fall and break. Therefore, alkali-free glass fiber is used, and under the action of branched linear low-density polyethylene grafts, a winding and coating effect is obtained, so that the prepared polypropylene composite material has high rigidity and high elongation at break, thereby having good toughness and resistance to falling.

[0016] Preferably, the temperature curve is divided into four parts: feeding zone, plasticizing zone, homogenizing zone and outlet zone. The temperature of the feeding zone is controlled at 160-180°C, the temperature of the plasticizing zone is controlled at 190-210°C, the temperature of the homogenizing zone is controlled at 200-220°C, and the temperature of the outlet zone is controlled at 205-225°C.

[0017] Preferably, the shear rate is 300-600s -1 , residence time 1-5min.

[0018] Compared with the prior art, the present invention has the following beneficial effects: In the high-rigidity and high-toughness seat PP composite material and its preparation method, linear low-density polyethylene grafts are used to enhance the interface interaction between polypropylene and linear low-density polyethylene and improve the compatibility between the two, thereby increasing the elongation at break of the material, enhancing the rigidity of the composite material, and having better toughness and drop resistance. In addition, alkali-free glass fiber is used instead of ordinary glass fiber to provide a stronger reinforcement effect. At the same time, the long side chains of the linear low-density polyethylene grafts can produce a entanglement and coating effect on the alkali-free glass fiber, thereby enhancing the interaction of the composite material and improving the mechanical properties of the seat. In addition, the macromolecular dispersant used can better promote the coupling and combination of inorganic fillers, alkali-free glass fibers and polypropylene substrates, improve micro-compatibility, and make the prepared polypropylene composite material have high rigidity and high toughness, meeting the requirements that the prepared protective seat has both excellent rigidity and good resilience and is not easy to deform. DETAILED DESCRIPTION

[0019] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] A high-rigidity and high-toughness seat PP composite material of the present invention comprises the following components: 30-50 parts by weight of polypropylene, 10-25 parts by weight of high-density polyethylene, 3-6 parts by weight of linear low-density polyethylene graft, 10-20 parts by weight of inorganic filler, 5-10 parts by weight of alkali-free glass fiber, 0.3-0.6 parts by weight of coupling agent, 1-2 parts by weight of macromolecular dispersant and 0.2-0.5 parts by weight of antioxidant; The linear low-density polyethylene graft is prepared by mixing linear low-density polyethylene, 3-(vinyloxy)propane-1-amine and dielectric acid in a mass ratio of 10:0.1-0.5:2-3; The macromolecular dispersant is obtained by mixing maleic anhydride grafted polypropylene and 3-(ureaamino)propyltriethoxysilane in a mass ratio of 1:1.5-1.7.

[0021] Among them, the preferred inorganic filler is calcium carbonate; the coupling agent is γ-aminopropyltriethoxysilane; and the antioxidant is tris[2.4-di-tert-butylphenyl]phosphite.

[0022] Embodiment 1: A high-rigidity and high-toughness seat PP composite material and a preparation method thereof, comprising the following steps: Prepare components: 50 parts by weight of polypropylene, 25 parts by weight of high-density polyethylene, 6 parts by weight of linear low-density polyethylene graft, 20 parts by weight of calcium carbonate, 10 parts by weight of alkali-free glass fiber, 0.6 parts by weight of γ-aminopropyltriethoxysilane, 2 parts by weight of macromolecular dispersant and 0.5 parts by weight of tris[2.4-di-tert-butylphenyl]phosphite; The linear low-density polyethylene graft is prepared by mixing linear low-density polyethylene, 3-(vinyloxy)propane-1-amine and dielectric acid in a mass ratio of 10:0.1:2; the macromolecular dispersant is prepared by mixing maleic anhydride grafted polypropylene and 3-(ureaamino)propyltriethoxysilane in a mass ratio of 1:1.5; The diisopropylbenzene peroxide accounts for 2% of the mass of the linear low-density polyethylene; the molar ratio of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, 4-dimethylaminopyridine, triethylamine and erucic acid is 1.5:0.5:1:1; Putting linear low-density polyethylene, 3-(vinyloxy)prop-1-amine and diisopropylbenzene peroxide into a high-speed mixer, mixing them evenly at room temperature to ensure that the components are evenly distributed, adding the mixed materials into an internal mixer, setting the temperature to 170°C, the speed to 50rpm, and the mixing time to 15min. After the mixing is completed, the product is immediately taken out and quickly cooled to obtain a preliminarily modified linear low-density polyethylene; putting the preliminarily modified linear low-density polyethylene, erucic acid, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, 4-dimethylaminopyridine and triethylamine into the internal mixer again, setting the reaction temperature to 160°C, holding time for 2h, after the reaction is completed, taking out and quickly cooling, and then making pellets of the product to obtain a linear low-density polyethylene graft; Dissolve maleic anhydride grafted polypropylene in dichloromethane to prepare a 5% w / v solution, add 4-dimethylaminopyridine to obtain a mixed solution, wherein the amount of dimethylaminopyridine added is 1% of the mass of the maleic anhydride grafted polypropylene, and under nitrogen protection, dropwise add 3-(ureaamino)propyltriethoxysilane to the mixed solution while maintaining stirring, heat the reaction mixture to 80° C., react for 4 hours, and after the reaction is completed, remove the solvent by a rotary evaporator to obtain a macromolecular dispersant; Add polypropylene, high-density polyethylene and linear low-density polyethylene grafts into a high-speed mixer, then add a coupling agent, an inorganic filler, a macromolecular dispersant and an antioxidant, and mix them thoroughly. Finally, add alkali-free glass fiber and continue mixing until uniform. Use a twin-screw extruder to melt blend the mixed materials, set the temperature curve, and control the shear rate and residence time. The temperature curve is divided into four parts: a feeding zone, a plasticizing zone, a homogenizing zone and an outlet zone. The temperature of the feeding zone is controlled at 160°C, the temperature of the plasticizing zone is controlled at 190°C, the temperature of the homogenizing zone is controlled at 200°C, the temperature of the outlet zone is controlled at 225°C, and the shear rate is 600s. -1 , residence time is 5min, and finally the composite material is extruded through an injection molding machine to obtain a high stiffness and high toughness seat PP composite material.

[0023] Embodiment 2: A high-rigidity and high-toughness seat PP composite material and a preparation method thereof, comprising the following steps: Prepare components: 50 parts by weight of polypropylene, 25 parts by weight of high-density polyethylene, 6 parts by weight of linear low-density polyethylene graft, 20 parts by weight of calcium carbonate, 10 parts by weight of alkali-free glass fiber, 0.6 parts by weight of γ-aminopropyltriethoxysilane, 2 parts by weight of macromolecular dispersant and 0.5 parts by weight of tris[2.4-di-tert-butylphenyl]phosphite; The linear low-density polyethylene graft is prepared by mixing linear low-density polyethylene, 3-(vinyloxy)propane-1-amine and dielectric acid in a mass ratio of 10:0.3:2.5; the macromolecular dispersant is prepared by mixing maleic anhydride grafted polypropylene and 3-(ureaamino)propyltriethoxysilane in a mass ratio of 1:1.6; The diisopropylbenzene peroxide accounts for 2% of the mass of the linear low-density polyethylene; the molar ratio of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, 4-dimethylaminopyridine, triethylamine and erucic acid is 1.5:0.5:1:1; Putting linear low-density polyethylene, 3-(vinyloxy)prop-1-amine and diisopropylbenzene peroxide into a high-speed mixer, mixing them evenly at room temperature to ensure that the components are evenly distributed, adding the mixed materials into an internal mixer, setting the temperature to 170°C, the speed to 50rpm, and the mixing time to 15min. After the mixing is completed, the product is immediately taken out and quickly cooled to obtain a preliminarily modified linear low-density polyethylene; putting the preliminarily modified linear low-density polyethylene, erucic acid, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, 4-dimethylaminopyridine and triethylamine into the internal mixer again, setting the reaction temperature to 160°C, holding time for 2h, after the reaction is completed, taking out and quickly cooling, and then making pellets of the product to obtain a linear low-density polyethylene graft; Dissolve maleic anhydride grafted polypropylene in dichloromethane to prepare a 5% w / v solution, add 4-dimethylaminopyridine to obtain a mixed solution, wherein the amount of dimethylaminopyridine added is 1% of the mass of the maleic anhydride grafted polypropylene, and under nitrogen protection, dropwise add 3-(ureaamino)propyltriethoxysilane to the mixed solution while maintaining stirring, heat the reaction mixture to 80° C., react for 4 hours, and after the reaction is completed, remove the solvent by a rotary evaporator to obtain a macromolecular dispersant; Add polypropylene, high-density polyethylene and linear low-density polyethylene grafts into a high-speed mixer, then add a coupling agent, an inorganic filler, a macromolecular dispersant and an antioxidant, and mix them thoroughly. Finally, add alkali-free glass fiber and continue mixing until uniform. Use a twin-screw extruder to melt blend the mixed materials, set the temperature curve, and control the shear rate and residence time. The temperature curve is divided into four parts: a feeding zone, a plasticizing zone, a homogenizing zone and an outlet zone. The temperature of the feeding zone is controlled at 160°C, the temperature of the plasticizing zone is controlled at 190°C, the temperature of the homogenizing zone is controlled at 200°C, the temperature of the outlet zone is controlled at 225°C, and the shear rate is 600s. -1 , residence time is 5min, and finally the composite material is extruded through an injection molding machine to obtain a high stiffness and high toughness seat PP composite material.

[0024] Embodiment 3: A high-rigidity and high-toughness seat PP composite material and a preparation method thereof, comprising the following steps: Prepare components: 50 parts by weight of polypropylene, 25 parts by weight of high-density polyethylene, 6 parts by weight of linear low-density polyethylene graft, 20 parts by weight of calcium carbonate, 10 parts by weight of alkali-free glass fiber, 0.6 parts by weight of γ-aminopropyltriethoxysilane, 2 parts by weight of macromolecular dispersant and 0.5 parts by weight of tris[2.4-di-tert-butylphenyl]phosphite; The linear low-density polyethylene graft is prepared by mixing linear low-density polyethylene, 3-(vinyloxy)propane-1-amine and dielectric acid in a mass ratio of 10:0.5:3; the macromolecular dispersant is prepared by mixing maleic anhydride grafted polypropylene and 3-(ureaamino)propyltriethoxysilane in a mass ratio of 1:1.7; The diisopropylbenzene peroxide accounts for 2% of the mass of the linear low-density polyethylene; the molar ratio of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, 4-dimethylaminopyridine, triethylamine and erucic acid is 1.5:0.5:1:1; Putting linear low-density polyethylene, 3-(vinyloxy)prop-1-amine and diisopropylbenzene peroxide into a high-speed mixer, mixing them evenly at room temperature to ensure that the components are evenly distributed, adding the mixed materials into an internal mixer, setting the temperature to 170°C, the speed to 50rpm, and the mixing time to 15min. After the mixing is completed, the product is immediately taken out and quickly cooled to obtain a preliminarily modified linear low-density polyethylene; putting the preliminarily modified linear low-density polyethylene, erucic acid, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, 4-dimethylaminopyridine and triethylamine into the internal mixer again, setting the reaction temperature to 160°C, holding time for 2h, after the reaction is completed, taking out and quickly cooling, and then making pellets of the product to obtain a linear low-density polyethylene graft; Dissolve maleic anhydride grafted polypropylene in dichloromethane to prepare a 5% w / v solution, add 4-dimethylaminopyridine to obtain a mixed solution, wherein the amount of dimethylaminopyridine added is 1% of the mass of the maleic anhydride grafted polypropylene, and under nitrogen protection, dropwise add 3-(ureaamino)propyltriethoxysilane to the mixed solution while maintaining stirring, heat the reaction mixture to 80° C., react for 4 hours, and after the reaction is completed, remove the solvent by a rotary evaporator to obtain a macromolecular dispersant; Add polypropylene, high-density polyethylene and linear low-density polyethylene grafts into a high-speed mixer, then add a coupling agent, an inorganic filler, a macromolecular dispersant and an antioxidant, and mix them thoroughly. Finally, add alkali-free glass fiber and continue mixing until uniform. Use a twin-screw extruder to melt blend the mixed materials, set the temperature curve, and control the shear rate and residence time. The temperature curve is divided into four parts: a feeding zone, a plasticizing zone, a homogenizing zone and an outlet zone. The temperature of the feeding zone is controlled at 160°C, the temperature of the plasticizing zone is controlled at 190°C, the temperature of the homogenizing zone is controlled at 200°C, the temperature of the outlet zone is controlled at 225°C, and the shear rate is 600s. -1 , residence time is 5min, and finally the composite material is extruded through an injection molding machine to obtain a high stiffness and high toughness seat PP composite material.

[0025] Embodiment 4: A high-rigidity and high-toughness seat PP composite material and a preparation method thereof, comprising the following steps: Prepare components: 30 parts by weight of polypropylene, 10 parts by weight of high-density polyethylene, 6 parts by weight of linear low-density polyethylene graft, 10 parts by weight of calcium carbonate, 5 parts by weight of alkali-free glass fiber, 0.3 parts by weight of γ-aminopropyltriethoxysilane, and macromolecular dispersant 2 parts by weight and 0.2 parts by weight of tris[2,4-di-tert-butylphenyl]phosphite; The linear low-density polyethylene graft is prepared by mixing linear low-density polyethylene, 3-(vinyloxy)propane-1-amine and dielectric acid in a mass ratio of 10:0.5:3; the macromolecular dispersant is prepared by mixing maleic anhydride grafted polypropylene and 3-(ureaamino)propyltriethoxysilane in a mass ratio of 1:1.7; The diisopropylbenzene peroxide accounts for 0.5% of the mass of the linear low-density polyethylene; the molar ratio of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, 4-dimethylaminopyridine, triethylamine and erucic acid is 1:0.1:1:1; Putting linear low-density polyethylene, 3-(vinyloxy)prop-1-amine and diisopropylbenzene peroxide into a high-speed mixer, mixing them evenly at room temperature to ensure that the components are evenly distributed, adding the mixed materials into an internal mixer, setting the temperature to 170°C, the speed to 50rpm, and the mixing time to 15min. After the mixing is completed, the product is immediately taken out and quickly cooled to obtain a preliminarily modified linear low-density polyethylene; putting the preliminarily modified linear low-density polyethylene, erucic acid, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, 4-dimethylaminopyridine and triethylamine into the internal mixer again, setting the reaction temperature to 160°C, holding time for 2h, after the reaction is completed, taking out and quickly cooling, and then making pellets of the product to obtain a linear low-density polyethylene graft; Dissolve maleic anhydride grafted polypropylene in dichloromethane to prepare a 5% w / v solution, add 4-dimethylaminopyridine to obtain a mixed solution, wherein the amount of dimethylaminopyridine added is 1% of the mass of the maleic anhydride grafted polypropylene, and under nitrogen protection, dropwise add 3-(ureaamino)propyltriethoxysilane to the mixed solution while maintaining stirring, heat the reaction mixture to 80° C., react for 4 hours, and after the reaction is completed, remove the solvent by a rotary evaporator to obtain a macromolecular dispersant; Add polypropylene, high-density polyethylene and linear low-density polyethylene grafts into a high-speed mixer, then add a coupling agent, an inorganic filler, a macromolecular dispersant and an antioxidant, and mix them thoroughly. Finally, add alkali-free glass fiber and continue mixing until uniform. Use a twin-screw extruder to melt blend the mixed materials, set the temperature curve, and control the shear rate and residence time. The temperature curve is divided into four parts: a feeding zone, a plasticizing zone, a homogenizing zone and an outlet zone. The temperature of the feeding zone is controlled at 160°C, the temperature of the plasticizing zone is controlled at 190°C, the temperature of the homogenizing zone is controlled at 200°C, the temperature of the outlet zone is controlled at 225°C, and the shear rate is 600s. -1 , residence time is 5min, and finally the composite material is extruded through an injection molding machine to obtain a high stiffness and high toughness seat PP composite material.

[0026] Embodiment 5: A high-rigidity and high-toughness seat PP composite material and a preparation method thereof, comprising the following steps: Prepare components: 50 parts by weight of polypropylene, 25 parts by weight of high-density polyethylene, 3 parts by weight of linear low-density polyethylene graft, 20 parts by weight of calcium carbonate, 10 parts by weight of alkali-free glass fiber, 0.6 parts by weight of γ-aminopropyltriethoxysilane, 1 part by weight of macromolecular dispersant and 0.5 parts by weight of tris[2.4-di-tert-butylphenyl]phosphite; The linear low-density polyethylene graft is prepared by mixing linear low-density polyethylene, 3-(vinyloxy)propane-1-amine and dielectric acid in a mass ratio of 10:0.5:3; the macromolecular dispersant is prepared by mixing maleic anhydride grafted polypropylene and 3-(ureaamino)propyltriethoxysilane in a mass ratio of 1:1.7; The diisopropylbenzene peroxide accounts for 2% of the mass of the linear low-density polyethylene; the molar ratio of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, 4-dimethylaminopyridine, triethylamine and erucic acid is 1.5:0.5:1:1; Putting linear low-density polyethylene, 3-(vinyloxy)prop-1-amine and diisopropylbenzene peroxide into a high-speed mixer, mixing them evenly at room temperature to ensure that the components are evenly distributed, adding the mixed materials into an internal mixer, setting the temperature to 170°C, the speed to 50rpm, and the mixing time to 15min. After the mixing is completed, the product is immediately taken out and quickly cooled to obtain a preliminarily modified linear low-density polyethylene; putting the preliminarily modified linear low-density polyethylene, erucic acid, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, 4-dimethylaminopyridine and triethylamine into the internal mixer again, setting the reaction temperature to 160°C, holding time for 2h, after the reaction is completed, taking out and quickly cooling, and then making pellets of the product to obtain a linear low-density polyethylene graft; Dissolve maleic anhydride grafted polypropylene in dichloromethane to prepare a 5% w / v solution, add 4-dimethylaminopyridine to obtain a mixed solution, wherein the amount of dimethylaminopyridine added is 1% of the mass of the maleic anhydride grafted polypropylene, and under nitrogen protection, dropwise add 3-(ureaamino)propyltriethoxysilane to the mixed solution while maintaining stirring, heat the reaction mixture to 80° C., react for 4 hours, and after the reaction is completed, remove the solvent by a rotary evaporator to obtain a macromolecular dispersant; Add polypropylene, high-density polyethylene and linear low-density polyethylene grafts into a high-speed mixer, then add a coupling agent, an inorganic filler, a macromolecular dispersant and an antioxidant, and mix them thoroughly. Finally, add alkali-free glass fiber and continue mixing until uniform. Use a twin-screw extruder to melt blend the mixed materials, set the temperature curve, and control the shear rate and residence time. The temperature curve is divided into four parts: a feeding zone, a plasticizing zone, a homogenizing zone and an outlet zone. The temperature of the feeding zone is controlled at 160°C, the temperature of the plasticizing zone is controlled at 190°C, the temperature of the homogenizing zone is controlled at 200°C, the temperature of the outlet zone is controlled at 225°C, and the shear rate is 600s. -1 , residence time is 5min, and finally the composite material is extruded through an injection molding machine to obtain a high stiffness and high toughness seat PP composite material.

[0027] Embodiment 6: A high-rigidity and high-toughness seat PP composite material and a preparation method thereof, comprising the following steps: Prepare components: 50 parts by weight of polypropylene, 25 parts by weight of high-density polyethylene, 5 parts by weight of linear low-density polyethylene graft, 20 parts by weight of calcium carbonate, 10 parts by weight of alkali-free glass fiber, 0.6 parts by weight of γ-aminopropyltriethoxysilane, 1.5 parts by weight of macromolecular dispersant and 0.5 parts by weight of tris[2,4-di-tert-butylphenyl]phosphite; The linear low-density polyethylene graft is prepared by mixing linear low-density polyethylene, 3-(vinyloxy)propane-1-amine and dielectric acid in a mass ratio of 10:0.5:3; the macromolecular dispersant is prepared by mixing maleic anhydride grafted polypropylene and 3-(ureaamino)propyltriethoxysilane in a mass ratio of 1:1.7; The diisopropylbenzene peroxide accounts for 2% of the mass of the linear low-density polyethylene; the molar ratio of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, 4-dimethylaminopyridine, triethylamine and erucic acid is 1.5:0.5:1:1; Putting linear low-density polyethylene, 3-(vinyloxy)prop-1-amine and diisopropylbenzene peroxide into a high-speed mixer, mixing them evenly at room temperature to ensure that the components are evenly distributed, adding the mixed materials into an internal mixer, setting the temperature to 170°C, the speed to 50rpm, and the mixing time to 15min. After the mixing is completed, the product is immediately taken out and quickly cooled to obtain a preliminarily modified linear low-density polyethylene; putting the preliminarily modified linear low-density polyethylene, erucic acid, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, 4-dimethylaminopyridine and triethylamine into the internal mixer again, setting the reaction temperature to 160°C, holding time for 2h, after the reaction is completed, taking out and quickly cooling, and then making pellets of the product to obtain a linear low-density polyethylene graft; Dissolve maleic anhydride grafted polypropylene in dichloromethane to prepare a 5% w / v solution, add 4-dimethylaminopyridine to obtain a mixed solution, wherein the amount of dimethylaminopyridine added is 1% of the mass of the maleic anhydride grafted polypropylene, and under nitrogen protection, dropwise add 3-(ureaamino)propyltriethoxysilane to the mixed solution while maintaining stirring, heat the reaction mixture to 80° C., react for 4 hours, and after the reaction is completed, remove the solvent by a rotary evaporator to obtain a macromolecular dispersant; Add polypropylene, high-density polyethylene and linear low-density polyethylene grafts into a high-speed mixer, then add a coupling agent, an inorganic filler, a macromolecular dispersant and an antioxidant, and mix them thoroughly. Finally, add alkali-free glass fiber and continue mixing until uniform. Use a twin-screw extruder to melt blend the mixed materials, set the temperature curve, and control the shear rate and residence time. The temperature curve is divided into four parts: a feeding zone, a plasticizing zone, a homogenizing zone and an outlet zone. The temperature of the feeding zone is controlled at 160°C, the temperature of the plasticizing zone is controlled at 190°C, the temperature of the homogenizing zone is controlled at 200°C, the temperature of the outlet zone is controlled at 225°C, and the shear rate is 600s. -1 , residence time is 5min, and finally the composite material is extruded through an injection molding machine to obtain a high stiffness and high toughness seat PP composite material.

[0028] Comparative Example 1: The method of Example 3 was adopted without adding the linear low-density polyethylene graft.

[0029] Comparative Example 2: The method of Example 3 was adopted, and the linear low-density polyethylene was directly used without modifying the linear low-density polyethylene by 3-(vinyloxy)propan-1-amine and dielectric acid.

[0030] Comparative Example 3: The method of Example 3 was adopted, and 3-(vinyloxy)propan-1-amine and linear low-density polyethylene were directly used without modifying 3-(vinyloxy)propan-1-amine and linear low-density polyethylene by an intermediate acid.

[0031] Comparative Example 4: The method of Example 3 was adopted to directly use maleic anhydride grafted polypropylene without modifying the maleic anhydride grafted polypropylene by 3-(ureaamino)propyltriethoxysilane.

[0032] The present invention adopts a linear low-density polyethylene graft to prepare a high-rigidity and high-toughness seat PP composite material, wherein the performance index inspection items and inspection standards of the high-rigidity and high-toughness seat PP composite material are as follows: According to GB / T 1040.1-2018 "Determination of tensile properties of plastics", the tensile strength and elongation at break of the seat polypropylene composite material were tested. The tensile strength refers to the maximum stress that the material can withstand before breaking, while the elongation at break reflects the percentage change in the relative length of the material when it breaks. These two parameters comprehensively evaluate the tensile strength and elastic recovery ability of the material; according to GB / T 9341-2008 "Determination of flexural properties of plastics", the flexural strength, flexural modulus and cantilever beam notched impact strength of the seat polypropylene composite material were tested. The flexural strength refers to the maximum stress that the material can withstand under three-point bending or four-point bending conditions, the flexural modulus reflects the ability of the material to resist bending deformation, and the cantilever beam notched impact strength evaluates the ability of the material to resist sudden impact loads; according to GB / T 3682-2000 "Determination of mass flow rate and volume flow rate of thermoplastic melts", the melt index of the seat polypropylene composite material was tested. The melt index is the mass of thermoplastic plastic flowing out of an orifice of specified diameter and length within a certain period of time at a specific temperature and pressure, which is used to characterize the fluidity of the plastic.

[0033] After the seat is fixed, use a tensile tester to stretch the chair back and test the tensile force used under the same displacement and deformation. The larger the tensile force, the stronger the product rigidity. Test the tensile force at room temperature of 25℃ with a displacement of 5cm and 10cm respectively. Keep it in a thermostatic bath at 40℃ for 1 hour and test the tensile force at a displacement of 5cm and 10cm within 5 minutes after taking it out. Keep it in a thermostatic bath at 80℃ for 1 hour and test the tensile force at a displacement of 5cm and 10cm within 5 minutes after taking it out.

[0034] After fixing the seat, use a tensile tester to stretch the seat back. Apply the same tensile force of 200N and pull it back and forth 100 times to test the displacement of the seat under the same tensile condition. The smaller the displacement, the smaller the deformation of the product and the better the resilience, thereby determining the resilience and deformability of the seat.

[0035] According to the above standards, the high stiffness and high toughness seat PP composite materials prepared in the above Examples 1-6 and Comparative Examples 1-4 were tested, and the obtained data are shown in Table 1, Table 2 and Table 3: Table 1 Performance data of Examples 1-6 and Comparative Examples 1-4

[0036] Table 2 Performance data of Examples 1-6 and Comparative Examples 1-4

[0037] Table 3 Performance data of Examples 1-6 and Comparative Examples 1-4

[0038] The above data fully show that compared with Comparative Examples 1-4, Examples 1-6 can fully show the effect of linear low-density polyethylene grafts on the stiffness and toughness properties of the seat polypropylene composite material.

[0039] Since the present invention adopts a linear low-density polyethylene graft to prepare a high-rigidity and high-toughness seat PP composite material, the performance of the high-rigidity and high-toughness seat PP composite material is effectively improved by the linear low-density polyethylene graft, as follows: It can be seen from Examples 1-3 that with the increasing proportion of linear low-density polyethylene grafts and macromolecular dispersant components, the stiffness and toughness of the seat polypropylene composite material are significantly improved, indicating that 3-(vinyloxy)propane-1-amine provides amino groups, which enhances the polarity of linear low-density polyethylene, while the dielectric acid promotes the formation of hydrogen bonds or chemical bonds between linear low-density polyethylene and the inorganic filler and alkali-free glass fiber surface through the long branched structure, thereby improving the compatibility and interfacial bonding force, and enhancing the interaction between molecules, increasing the cohesion of the material, making the composite material less likely to break when subjected to external force, and improving its toughness and elongation at break. At the same time, the addition of macromolecular dispersants utilizes the active groups on maleic anhydride and 3-(ureaamino)propyltriethoxysilane to interact with the inorganic filler and alkali-free glass fiber, reducing microscopic defects through good interfacial compatibility, and making the internal stress distribution of the material more uniform, so that the composite material has higher stiffness and toughness.

[0040] It can be seen from Examples 2 and 4 that with the continuous change of the content of other components, the stiffness and toughness of the seat polypropylene composite material do not change significantly, indicating that small changes in other components within a certain range are not sufficient to significantly affect the stiffness and toughness of the seat polypropylene composite material.

[0041] It can be seen from Examples 2, 5 and 6 that with the continuous change of the content of linear low-density polyethylene grafts and macromolecular dispersants, the stiffness and toughness of the seat polypropylene composite materials continue to change. More linear low-density polyethylene grafts mean that there are more active functional groups in the composite material that can participate in the interaction between inorganic fillers and alkali-free glass fibers, thereby more effectively promoting dispersion and coupling, and the reinforcing effects of alkali-free glass fibers and inorganic fillers are fully exerted. A high content of macromolecular dispersants helps to disperse the fillers more evenly, reduce agglomeration, optimize the microstructure of the composite material, and improve the mechanical properties.

[0042] According to the above test experiments, the high stiffness and high toughness seat PP composite material prepared according to Example 3 has the best performance, so Example 3 is taken as the best example; By comparing Example 3 with Comparative Examples 1-4, it can be seen that: In comparative example 1, no linear low-density polyethylene grafts were added, and the stiffness and toughness of the seat polypropylene composite material were worse. Due to the lack of the introduction of grafts, the interfacial force between the polypropylene matrix and the inorganic filler was weak, and the filler agglomeration phenomenon was serious, resulting in internal stress concentration of the material and decreased mechanical properties. Therefore, 3-(vinyloxy)propan-1-amine and intercalary acid grafts of linear low-density polyethylene are crucial in enhancing interface compatibility and dispersion uniformity.

[0043] Comparative Example 2 directly uses linear low-density polyethylene without modifying it through 3-(vinyloxy)propane-1-amine and dielectric acid. The stiffness and toughness of the seat polypropylene composite material are poor. This is because the unmodified linear low-density polyethylene lacks polar groups, the interfacial bonding force between it and the inorganic filler and glass fiber is weak, and the filler is unevenly dispersed, affecting the overall performance of the material.

[0044] Comparative Example 3 directly uses 3-(vinyloxy)propan-1-amine and linear low-density polyethylene, and does not modify 3-(vinyloxy)propan-1-amine and linear low-density polyethylene by dielectric acid. The stiffness and toughness of the seat polypropylene composite material are poor. Since the chain segments of 3-(vinyloxy)propan-1-amine are short and the side chain extension effect of erucic acid is lacking, the intermolecular entanglement and coating effects are insufficient, which leads to a decrease in interfacial bonding strength and impact toughness. Therefore, the stiffness and toughness of the seat polypropylene composite material are reduced.

[0045] Comparative Example 4 directly uses maleic anhydride grafted polypropylene, and does not modify the maleic anhydride grafted polypropylene by 3-(ureaamino)propyltriethoxysilane. The stiffness and toughness of the seat polypropylene composite material are poor. The unmodified maleic anhydride grafted polypropylene only provides carboxyl force. Although it can provide a certain interface bonding force, its functional group is single. The functional groups of the maleic anhydride grafted polypropylene modified by 3-(ureaamino)propyltriethoxysilane are diversified. Therefore, the unmodified maleic anhydride grafted polypropylene has relatively poor affinity for inorganic fillers, which leads to a decrease in the stiffness and toughness of the seat polypropylene composite material.

[0046] In summary, through the interaction of linear low-density polyethylene grafts, macromolecular dispersants, alkali-free glass fibers and inorganic fillers, the compatibility of seat polypropylene composites can be improved through the polar groups of 3-(vinyloxy)propan-1-amine and the long side chains of the dielectric acid. By utilizing the carboxyl groups of maleic anhydride grafted polypropylene and the siloxane of 3-(ureaamino)propyltriethoxysilane, the affinity with inorganic fillers and alkali-free glass fibers can be improved through multiple active functional groups, thereby improving the mechanical properties of seat polypropylene composites, so that the seats of polypropylene composites have both excellent rigidity and good resilience and non-deformation properties.

[0047] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments, and the above embodiments and descriptions are only preferred examples of the present invention, and are not intended to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A high stiffness and high toughness seat PP composite material, characterized in that: The invention comprises the following components: 30-50 parts by weight of polypropylene, 10-25 parts by weight of high-density polyethylene, 3-6 parts by weight of linear low-density polyethylene graft, 10-20 parts by weight of inorganic filler, 5-10 parts by weight of alkali-free glass fiber, 0.3-0.6 parts by weight of coupling agent, 1-2 parts by weight of macromolecular dispersant and 0.2-0.5 parts by weight of antioxidant; The linear low-density polyethylene graft is prepared by mixing linear low-density polyethylene, 3-(vinyloxy)propane-1-amine and dielectric acid in a mass ratio of 10:0.1-0.5:2-3; The macromolecular dispersant is obtained by mixing maleic anhydride grafted polypropylene and 3-(ureaamino)propyltriethoxysilane in a mass ratio of 1:1.5-1.

7.

2. The high-rigidity and high-toughness seat PP composite material according to claim 1, characterized in that: The inorganic filler is one or more combinations of calcium carbonate, talc, mica powder, wollastonite, kaolin, magnesium hydroxide and aluminum hydroxide.

3. The high-rigidity and high-toughness seat PP composite material according to claim 1, characterized in that: The coupling agent is one or more combinations of gamma-aminopropyltriethoxysilane, vinyltrimethoxysilane and bis(dioctylpyrophosphate)titanate diisopropyl ester.

4. The high-rigidity and high-toughness seat PP composite material according to claim 1, characterized in that: The antioxidant is one or more combinations of 3,5-di-tert-butyl-4-hydroxyphenylpropionic acid n-octadecyl alcohol ester, tris[2,4-di-tert-butylphenyl]phosphite and didodecylthiodipropionate.

5. The high stiffness and high toughness seat PP composite material according to claim 1, characterized in that: The preparation method of the linear low density polyethylene graft is as follows: Put linear low-density polyethylene, 3-(vinyloxy)prop-1-amine and diisopropylbenzene peroxide into a high-speed mixer, mix them evenly at room temperature to ensure that the components are evenly distributed, add the mixed materials into an internal mixer, set the temperature to 160-190°C, the rotation speed to 40-50rpm, and the mixing time to 15-20min. After the mixing is completed, immediately take out the product and quickly cool it to obtain a preliminary modified linear low-density polyethylene; put the preliminary modified linear low-density polyethylene, erucic acid, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, 4-dimethylaminopyridine and triethylamine into the internal mixer again, set the reaction temperature to 150-170°C, keep it for 1-2h, after the reaction is completed, immediately take it out and quickly cool it, and then make the product into pellets to obtain a linear low-density polyethylene graft.

6. The high-rigidity and high-toughness seat PP composite material according to claim 5, characterized in that: The diisopropylbenzene peroxide accounts for 0.5-2% of the mass of the linear low-density polyethylene; the molar ratio of the 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, 4-dimethylaminopyridine, triethylamine and erucic acid is 1-1.5:0.1-0.5:1:

1.

7. The high-rigidity and high-toughness seat PP composite material according to claim 1, characterized in that: The preparation method of the macromolecular dispersant is as follows: The maleic anhydride grafted polypropylene is dissolved in dichloromethane to prepare a 3-8% w / v solution, and 4-dimethylaminopyridine is added to obtain a mixed solution, wherein the amount of dimethylaminopyridine added is 0.1-5% of the mass of the maleic anhydride grafted polypropylene. Under nitrogen protection, 3-(ureaamino)propyltriethoxysilane is added dropwise to the mixed solution while stirring, and the reaction mixture is heated to 60-80°C for 4-6 hours. After the reaction is completed, the solvent is removed by a rotary evaporator to obtain a macromolecular dispersant.

8. A method for preparing a high-rigidity and high-toughness seat PP composite material, used for preparing the high-rigidity and high-toughness seat PP composite material according to any one of claims 1 to 7, characterized in that: The steps include: Add polypropylene, high-density polyethylene and linear low-density polyethylene grafts into a high-speed mixer, then add coupling agent, inorganic filler, macromolecular dispersant and antioxidant, and mix thoroughly. Finally, add alkali-free glass fiber and continue mixing until uniform. Use a twin-screw extruder to melt blend the mixed materials, set the temperature curve, control the shear rate and residence time, and finally extrude the composite material through an injection molding machine to obtain a high-stiffness and high-toughness seat PP composite material.

9. The method for preparing the high-rigidity and high-toughness seat PP composite material according to claim 8, characterized in that: The temperature curve is divided into four parts: feeding zone, plasticizing zone, homogenizing zone and outlet zone. The temperature of the feeding zone is controlled at 160-180°C, the temperature of the plasticizing zone is controlled at 190-210°C, the temperature of the homogenizing zone is controlled at 200-220°C, and the temperature of the outlet zone is controlled at 205-225°C.

10. The method for preparing the high-rigidity and high-toughness seat PP composite material according to claim 8, characterized in that: The shear rate is 300-600s -1 , residence time 1-5min.

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