Preparation method of functional glass fiber reinforced composite plastic product

Abstract

The invention relates to the technical field of plastic processing, and discloses a preparation method of a functional glass fiber reinforced composite plastic product, and the composite plastic product comprises the following raw materials by mass: 44-50 parts of epoxy resin; 35 to 42 parts of modified phenolic resin; 20 to 30 parts of unsaturated polyester resin; 26 to 33 parts of continuous glass fiber; 18 to 24 parts of glass fiber fabric; 2 to 4 parts of diethylenetriamine; 7 to 11 parts of methylhexahydrophthalic anhydride; 6-8 parts of styrene butadiene rubber; 3-7 parts of nano silicon dioxide; 0.6 to 0.9 part of quaternary ammonium salt; 2-5 parts of nickel-coated graphite powder; 7-12 parts of a phosphorus-based flame retardant; 0.2 to 0.6 part of an antioxidant; by reasonably proportioning the epoxy resin, the modified phenolic resin and the unsaturated polyester resin, an excellent comprehensive resin performance basis is provided, and continuous glass fibers and glass fiber fabrics are introduced as reinforcing materials, so that the overall strength and toughness of the material are further improved; the prepared composite plastic product has the advantages of good conductivity, high electromagnetic shielding effectiveness, strong flame retardant property, excellent mechanical property and good thermal stability.

Description

Technical Field

[0001] The invention relates to the technical field of plastic processing, in particular to a method for preparing a functional glass fiber reinforced composite plastic product. Background Art

[0002] With the continuous advancement of science and technology, the performance requirements for composite plastic products are becoming increasingly stringent. Not only must they possess excellent mechanical and thermal properties, but they must also meet the diverse functional requirements of conductivity, electromagnetic shielding, and flame retardancy. However, traditional composite plastic products have many shortcomings in terms of overall performance, making it difficult to meet the complex requirements of high-performance composite materials in modern industry.

[0003] Conventional composite plastics often struggle to achieve the desired electromagnetic shielding and electrical conductivity. Traditional materials lack sufficient electrical conductivity and electromagnetic shielding performance to effectively meet the stringent requirements for electromagnetic shielding and electrical conductivity in electronic equipment and other applications.

[0004] Traditional flame retardant methods have limited effectiveness. Existing flame retardant materials struggle to effectively isolate oxygen and heat during combustion, failing to prevent further flame spread. They also easily decompose or burn at high temperatures, resulting in a decrease in flame retardancy and making it difficult to meet the demands of high-safety applications.

[0005] Furthermore, traditional composite plastic products also suffer from deficiencies in mechanical and thermal properties. Suboptimal raw material formulations and manufacturing processes result in poor overall strength, toughness, and thermal stability. For example, mechanical properties such as tensile strength, flexural strength, and impact strength are low, making them unable to withstand complex mechanical stresses. Regarding thermal performance, the materials are prone to aging or deformation in high-temperature environments, resulting in a short service life and failing to meet the application requirements of high-performance composite plastic products.

[0006] In summary, the market currently lacks a method for preparing functional glass fiber reinforced composite plastic products that can comprehensively achieve the above-mentioned multiple performance improvements. Summary of the Invention

[0007] (1) Technical problems solved In response to the shortcomings of the existing technology, the present invention provides a method for preparing a functional glass fiber reinforced composite plastic product, which has the advantages of good conductivity, high electromagnetic shielding efficiency, strong flame retardant performance, excellent mechanical properties and good thermal stability, and solves the problems of traditional composite plastic products in insufficient electromagnetic shielding and conductivity, poor flame retardant effect, and low mechanical and thermal properties.

[0008] (2) Technical solution

[0009] To achieve the above object, the present invention provides the following technical solution: a method for preparing a functional glass fiber reinforced composite plastic product, comprising the following steps: S1. Prepare raw materials: prepare epoxy resin, modified phenolic resin, unsaturated polyester resin, continuous glass fiber, glass fiber fabric, diethylenetriamine, methylhexahydrophthalic anhydride, styrene-butadiene rubber, nano-silica, quaternary ammonium salt, nickel-coated graphite powder, phosphorus-based flame retardant, antioxidant and silane coupling agent as raw materials according to the formula ratio; S2, raw material pretreatment stage: soaking the continuous glass fiber and glass fiber fabric in a silane coupling agent, premixing the epoxy resin with diethylenetriamine, premixing the modified phenolic resin with methylhexahydrophthalic anhydride, and premixing the unsaturated polyester resin with styrene-butadiene rubber; S3, blending stage: After blending the pretreated epoxy resin, modified phenolic resin and unsaturated polyester resin, nano-silica and nickel-coated graphite powder are added to obtain a resin system; after blending the pretreated continuous glass fiber and glass fiber fabric, quaternary ammonium salt, phosphorus-based flame retardant and antioxidant are added to obtain a glass fiber system; S4. Extrusion molding: The resin system and the glass fiber system are mixed through an extruder, and after three temperature-controlled molding, a preliminarily formed composite plastic product is obtained.

[0010] Preferably, the raw materials of the composite plastic product and their weight parts include: 44-50 parts of epoxy resin; 35-42 parts of modified phenolic resin; 20-30 parts of unsaturated polyester resin; 26-33 parts of continuous glass fiber; 18-24 parts of glass fiber fabric; 2-4 parts of diethylenetriamine; 7-11 parts of methylhexahydrophthalic anhydride; 6-8 parts of styrene-butadiene rubber; 3-7 parts of nano-silica; 0.6-0.9 parts of quaternary ammonium salt; 2-5 parts of nickel-coated graphite powder; 7-12 parts of phosphorus flame retardant; 0.2-0.6 parts of antioxidant; and 0.5-1.2 parts of silane coupling agent.

[0011] Preferably, the unsaturated polyester resin is prepared from maleic anhydride, phthalic anhydride, ethylene glycol and p-toluenesulfonic acid, and its chemical reaction formula is: nHO-R-OH+mC=O→Polyester chain+H2O In the reaction formula, R is a diol alkyl chain, and the dotted box is a mixed anhydride of maleic anhydride and phthalic anhydride.

[0012] Preferably, the nickel-coated graphite powder preparation process is: S1.1. Graphite powder pretreatment: Graphite powder is ultrasonically cleaned with 60% to 65% concentrated nitric acid for 25-30 minutes. During this process, the concentrated nitric acid reacts with impurities on the graphite surface to produce carbon dioxide, nitrogen dioxide, and water. S1.2, Sensitization treatment: Immerse the pretreated graphite powder in SnCl2·2H2O solution and stir at room temperature for 30 minutes to allow the surface to adsorb Sn. 2+ , stannous chloride dissociates in water, causing Sn to be adsorbed on the graphite surface 2+ ; S1.3, activation treatment: the sensitized graphite powder is transferred into PdCl2 solution and stirred for 8-10 minutes to induce the formation of Pd catalytic active sites on the surface. The palladium ions are adsorbed and reduced to metallic palladium. At the same time, Sn 2+ Oxidized to Sn 4+ ; S1.4, Chemical Nickel Plating: Prepare a plating solution with a pH of 4.45-4.55 by adding 20 g / L NiSO4·6H2O, 25 g / L sodium hypophosphite, and 15 g / L sodium citrate. Heat to 80-85°C, add activated graphite powder, and mechanically stir under nitrogen protection. Allow to react for 2-2.15 hours. Nickel will be deposited on the graphite surface. The hypophosphite will reduce the nickel ions to metallic nickel and will be oxidized to phosphite. The chemical reaction formula is: Ni 2+ +H2PO 2− +H2O→Ni↓+H2PO 3− +2H + In the reaction formula, sodium citrate stabilizes the plating solution through complexation and does not participate in the redox reaction. Nitrogen protection prevents oxidation side reactions. S1.5. Post-treatment: The reaction product in S1.4 is washed with ethanol 3-8 times, and then dried under vacuum at 55-60° C. for 1.5-2 h to obtain nickel-coated graphite powder.

[0013] Preferably, the epoxy resin, modified phenolic resin and unsaturated polyester resin constitute the matrix resin; the continuous glass fiber and glass fiber fabric constitute the reinforcing material; the diethylenetriamine and methylhexahydrophthalic anhydride constitute the curing agent, and the styrene-butadiene rubber is a toughening agent; the nano-silica, quaternary ammonium salt, nickel-coated graphite powder and phosphorus-based flame retardant constitute the functional additives, and the antioxidant and silane coupling agent constitute the auxiliary agent.

[0014] Preferably, the raw material pretreatment conditions in S2 are: S2.1. Soak the continuous glass fiber and glass fiber fabric in a silane coupling agent for 1-2 hours, remove and rinse 2-4 times, and then dry at 55-60°C for 30-40 minutes. S2.2. Pre-react epoxy resin and diethylenetriamine in a water bath at 50-55°C for 8-12 minutes; S2.3. Premix the modified phenolic resin and methyl hexahydrophthalic anhydride in a water bath at 75-80°C and homogenize for 30-45 minutes; S2.4. Blend the unsaturated polyester resin and styrene-butadiene rubber at room temperature for 25-30 minutes.

[0015] Preferably, the epoxy resin, modified phenolic resin and unsaturated polyester resin in S3 are mixed with nano-silica and nickel-coated graphite powder and stirred at a speed of 500-600 r / min for 10-15 min. After stirring for 5 to 6 minutes, the solution temperature is raised to 125-130° C. to obtain a resin system, and then the resin system is transferred to a vacuum degassing device, the vacuum degree is controlled at -0.09 to -0.1 MPa, and the degassing time is 10-15 min.

[0016] Preferably, the continuous glass fiber and glass fiber fabric in S3 are stirred at a speed of 200-400 rpm after adding the quaternary ammonium salt, phosphorus-based flame retardant and antioxidant, and the stirring time is 5-10 min, and the solution temperature is maintained at 75-80°C.

[0017] Preferably, the extrusion molding conditions in S4 are as follows: the temperature of the front section of the extruder is controlled to be 160-165°C, the temperature of the middle section is controlled to be 195-200°C, the temperature of the rear section is controlled to be 215-220°C, and the screw speed is controlled to be 45-50r / min.

[0018] Preferably, the raw materials of the composite plastic product and their weight parts include: 45 parts of epoxy resin; 38 parts of modified phenolic resin; 25 parts of unsaturated polyester resin; 29 parts of continuous glass fiber; 20 parts of glass fiber fabric; 3 parts of diethylenetriamine; 9 parts of methylhexahydrophthalic anhydride; 7 parts of styrene-butadiene rubber; 5 parts of nano-silica; 0.8 parts of quaternary ammonium salt; 3 parts of nickel-coated graphite powder; 10 parts of phosphorus flame retardant; 0.4 parts of antioxidant; and 0.9 parts of silane coupling agent.

[0019] Compared with the prior art, the present invention provides a method for preparing a functional glass fiber reinforced composite plastic product, which has the following beneficial effects: The present invention achieves the beneficial effect of improving electromagnetic shielding effectiveness and electrical conductivity by adding nickel-coated graphite powder to composite plastic products. The nickel-coated graphite powder forms a dense nickel metal layer on the surface of the graphite powder through a chemical nickel plating process. This metal layer not only gives the graphite powder excellent electrical conductivity, but also improves its oxidation resistance and chemical stability. The electrical conductivity of the nickel-coated graphite powder mainly comes from the high electrical conductivity of the nickel layer and the electrical conductivity of the graphite itself. The synergistic effect of the two makes the composite material perform well in electrical conductivity. Therefore, the addition of nickel-coated graphite powder enables the composite plastic product to have excellent electrical conductivity and electromagnetic shielding function.

[0020] 2. The present invention achieves the beneficial effect of improving the flame retardant properties of composite plastic products by synergistically using a phosphorus-based flame retardant and a modified phenolic resin. The phosphorus-based flame retardant can promote the formation of a dense carbon layer in the base material during combustion. This carbon layer can effectively isolate oxygen and heat, preventing the further spread of flames, thereby playing a flame retardant role. The modified phenolic resin has high thermal stability and can maintain structural integrity at high temperatures. It will not easily decompose or burn, providing a heat-resistant foundation for the composite material and helping to improve the overall flame retardant properties. The synergistic effect of the phosphorus-based flame retardant and the modified phenolic resin can improve the flame retardant grade and oxygen index of the composite plastic product, ultimately improving the flame retardant properties of the composite plastic product.

[0021] 3. The present invention achieves the beneficial effect of comprehensively improving the mechanical and thermal properties of composite plastic products by optimizing the raw material formula and preparation process. By rationally proportioning epoxy resin, modified phenolic resin, and unsaturated polyester resin, the three work synergistically to provide an excellent comprehensive performance foundation for the composite plastic product. The introduction of continuous glass fiber and glass fiber fabric as reinforcement further improves the overall strength and toughness of the material. Finally, in combination with specific auxiliary materials and additives, diethylenetriamine and methylhexahydrophthalic anhydride serve as curing agents to improve the wear resistance and rigidity of the material. Quaternary ammonium salt, nickel-coated graphite powder, and phosphorus-based flame retardant impart antistatic, conductive, electromagnetic shielding, and flame retardant properties to the material. The antioxidant and silane coupling agent inhibit the thermal oxidative aging of the material and enhance the bonding strength between the glass fiber and the resin, respectively, extending the service life of the material. The synergistic effect of the above raw materials significantly improves the tensile strength, flexural strength, and impact strength of the composite plastic product of the present invention, meeting the application requirements of high-performance composite plastic products. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A flow chart was prepared for the present invention. DETAILED DESCRIPTION

[0023] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 making creative efforts are within the scope of protection of the present invention.

[0024] See also Figure 1 A method for preparing a functional glass fiber reinforced composite plastic product comprises the following steps: S1. Prepare raw materials: prepare epoxy resin, modified phenolic resin, unsaturated polyester resin, continuous glass fiber, glass fiber fabric, diethylenetriamine, methylhexahydrophthalic anhydride, styrene-butadiene rubber, nano-silica, quaternary ammonium salt, nickel-coated graphite powder, phosphorus-based flame retardant, antioxidant and silane coupling agent as raw materials according to the formula ratio; S2, raw material pretreatment stage: soaking the continuous glass fiber and glass fiber fabric in a silane coupling agent, premixing the epoxy resin with diethylenetriamine, premixing the modified phenolic resin with methylhexahydrophthalic anhydride, and premixing the unsaturated polyester resin with styrene-butadiene rubber; S3, blending stage: After blending the pretreated epoxy resin, modified phenolic resin and unsaturated polyester resin, nano-silica and nickel-coated graphite powder are added to obtain a resin system; after blending the pretreated continuous glass fiber and glass fiber fabric, quaternary ammonium salt, phosphorus-based flame retardant and antioxidant are added to obtain a glass fiber system; S4. Extrusion molding: The resin system and the glass fiber system are mixed through an extruder, and after three temperature-controlled molding, a preliminarily formed composite plastic product is obtained.

[0025] The advantages are: the present invention achieves the beneficial effect of comprehensively improving the mechanical properties and thermal properties of composite plastic products by optimizing the raw material formula and preparation process, and fully integrates the advantages of each resin by reasonably proportioning epoxy resin, modified phenolic resin and unsaturated polyester resin as resin matrices. Epoxy resin provides high mechanical strength and corrosion resistance, modified phenolic resin gives the material high temperature resistance and flame retardant properties, and unsaturated polyester resin ensures low cost and fast curing ability. The three work synergistically to provide an excellent comprehensive performance foundation for composite plastic products, and introduces continuous glass fiber and glass fiber fabric as reinforcing materials. After pre-treatment with a silane coupling agent, the continuous glass fiber has enhanced bonding with the resin matrix to improve the longitudinal strength of the composite material; the glass fiber fabric enhances the transverse tear resistance of the laminated structure, so that the composite material has good mechanical properties in all directions, further improving the overall strength and toughness of the material. Finally, combined with specific auxiliary materials and additives, diethylenetriamine and methylhexahydrobenzene Anhydride as a curing agent can accurately control the cross-linking rate and curing degree of the resin, ensuring that the material has good molding properties; styrene-butadiene rubber as a toughening agent effectively improves the impact toughness of the composite material; nano-silica enhances the interfacial bonding force and improves the wear resistance and rigidity of the material; quaternary ammonium salts, nickel-coated graphite powder and phosphorus-based flame retardants give the material multifunctional properties such as antistatic, conductivity, electromagnetic shielding and flame retardancy; antioxidants and silane coupling agents respectively inhibit the thermal oxidative aging of the material and enhance the bonding force between glass fiber and resin, extending the service life of the material. The synergistic effect of the above auxiliary materials and additives further optimizes the comprehensive performance of the composite plastic product, so that the composite plastic product of the present invention performs well in tensile strength, flexural strength and impact strength. At the same time, thermal performance indicators such as heat deformation temperature and oxygen index are also improved, meeting the application requirements of high-performance composite plastic products, and solving the problems of traditional composite plastic products in insufficient electromagnetic shielding and conductivity, poor flame retardant effect, and low mechanical and thermal properties.

[0026] Table 1: Raw material formula and its function Raw material name Mass range Function and Description Resin matrix epoxy resin 44-50 servings High mechanical strength, corrosion-resistant matrix Modified phenolic resin 35-42 servings High temperature resistance and flame retardancy synergistic matrix Unsaturated polyester resin 20-30 servings Low-cost, fast-curing auxiliary matrix Reinforcement materials Continuous glass fiber 26-33 servings Pre-treated with silane coupling agent to improve longitudinal strength fiberglass fabric 18-24 servings Laminated structure reinforced, transverse tear resistance Excipients and additives Diethylenetriamine (curing agent) 5-8 servings Special curing agent for epoxy resin, controlling cross-linking rate Methylhexahydrophthalic anhydride (curing agent) 4-8 servings Modified phenolic resin anhydride curing agent to improve heat resistance Styrene-butadiene rubber 6-10 servings Toughening agent, improving impact toughness (blended with resin) Nanosilica 5-10 servings Enhance interfacial bonding strength, improve wear resistance and rigidity Quaternary ammonium salts 1-3 servings Antistatic agent, reducing surface resistivity Nickel coated graphite powder 3-5 servings Conductive filler, synergistic with quaternary ammonium salt to achieve electromagnetic shielding function Phosphorus flame retardants 5-8 servings Flame retardant synergy (synergistic with modified phenolic resin) Antioxidant (Type 1010) 0.5-1 serving Inhibit thermal oxidative aging and extend life Silane coupling agent (KH-550) 0.5-1.5 servings Glass fiber surface pretreatment to improve resin-fiber bonding Specifically, unsaturated polyester resin is prepared from maleic anhydride (providing unsaturated double bonds), phthalic anhydride (adjusting molecular chain flexibility), ethylene glycol (as a chain extender) and p-toluenesulfonic acid (as a catalyst). Its chemical reaction formula is: nHO-R-OH+mC=O→Polyester chain+H2O In the reaction formula, R is a diol alkyl chain, and the dotted box is a mixed anhydride of maleic anhydride and phthalic anhydride.

[0027] Specifically, the preparation process of nickel-coated graphite powder is as follows: S1.1. Graphite powder pretreatment: Graphite powder is ultrasonically cleaned with 60% to 65% concentrated nitric acid for 25-30 minutes to remove surface impurities, washed with water until neutral, and dried. In this process, concentrated nitric acid reacts with impurities on the graphite surface (such as organic matter or metal oxides) to produce carbon dioxide, nitrogen dioxide, and water. The chemical reaction formula is: C+4HNO3→CO2↑+4NO2↑+2H2O In the reaction formula, C represents carbon in organic impurities, and HNO3 represents concentrated nitric acid. When the impurities contain metal oxides, the chemical reaction formula is: MxOy+2yHNO3→xM(NO3)z+yH2O In the reaction formula, MxOy represents the metal oxide impurities on the surface of graphite powder; S1.2, Sensitization treatment: Immerse the pretreated graphite powder in SnCl2·2H2O solution (concentration 10g / L, pH=2) and stir at room temperature for 30min to allow the surface to adsorb Sn. 2+ , stannous chloride dissociates in water, causing Sn to be adsorbed on the graphite surface 2+ , its chemical reaction formula is: SnCl2→Sn 2+ +2Cl − In the reaction formula, SnCl2 represents stannous chloride; S1.3, activation treatment: the sensitized graphite powder is transferred to PdCl2 solution and stirred for 8-10 minutes to induce the formation of Pd catalytic active sites on the surface. Palladium ions are adsorbed and reduced to metallic palladium, while Sn2+ is oxidized to Sn4+. The chemical reaction formula is: Pd2++Sn2+→Pd↓+Sn4+ In the reaction formula, Pd 2 represents palladium ion, Pd represents metallic palladium; S1.4, Chemical Nickel Plating: Prepare a plating solution with a pH of 4.45-4.55 by adding 20 g / L NiSO4·6H2O, 25 g / L sodium hypophosphite, and 15 g / L sodium citrate. Heat to 80-85°C, add activated graphite powder, and mechanically stir under nitrogen protection. Allow to react for 2-2.15 hours. Nickel will be deposited on the graphite surface. The hypophosphite will reduce the nickel ions to metallic nickel and will be oxidized to phosphite. The chemical reaction formula is: Ni 2+ +H2PO 2− +H2O→Ni↓+H2PO 3− +2H + In the reaction formula, sodium citrate stabilizes the plating solution through complexation and does not participate in the redox reaction. Nitrogen protection prevents oxidation side reactions. S1.5. Post-treatment: The reaction product in S1.4 is washed with ethanol 3-8 times and then dried under vacuum at 55-60°C for 1.5-2 hours to obtain nickel-coated graphite powder having a Ni content of 22-32 wt%. Principle: A dense metal layer is formed on the graphite surface through chemical nickel plating, which imparts conductivity and oxidation resistance.

[0028] Specifically, epoxy resin, modified phenolic resin and unsaturated polyester resin constitute the matrix resin; continuous glass fiber and glass fiber fabric constitute the reinforcing material; diethylenetriamine and methylhexahydrophthalic anhydride constitute the curing agent, and styrene-butadiene rubber is the toughening agent; nano-silica, quaternary ammonium salt, nickel-coated graphite powder and phosphorus-based flame retardant constitute the functional additives, and antioxidant and silane coupling agent constitute the auxiliary agent.

[0029] Specifically, the raw material pretreatment conditions in S2 are: S2.1. Soak the continuous glass fiber and glass fiber fabric in a silane coupling agent for 1-2 hours, remove and rinse 2-4 times, and then dry at 55-60°C for 30-40 minutes. S2.2. Pre-react epoxy resin and diethylenetriamine in a water bath at 50-55°C for 8-12 minutes; S2.3. Premix the modified phenolic resin and methyl hexahydrophthalic anhydride in a water bath at 75-80°C and homogenize for 30-45 minutes; S2.4. Blend the unsaturated polyester resin and styrene-butadiene rubber at room temperature for 25-30 minutes.

[0030] The advantage is that during the preparation process, through specific raw material pretreatment conditions, the continuous glass fiber and glass fiber fabric are immersed in a silane coupling agent and dried, which helps to improve the bonding strength between the glass fiber and the resin, thereby enhancing the thermal stability of the material and ultimately extending the service life of the material.

[0031] Specifically, the epoxy resin, modified phenolic resin and unsaturated polyester resin in S3 are mixed with nano-silica and nickel-coated graphite powder and stirred at a speed of 500-600 r / min for 10-15 minutes. After stirring for 5 to 6 minutes, the solution temperature is raised to 125-130°C. This heating process is to promote the uniform dispersion and preliminary reaction of the resin and additives to obtain a resin system. The resin system is then moved into a vacuum degassing device with a vacuum degree controlled at -0.09 to -0.1 MPa for 10-15 minutes to remove bubbles in the system and prevent holes in the product.

[0032] The advantages are: by adding nickel-coated graphite powder to composite plastic products, the beneficial effect of improving electromagnetic shielding effectiveness and conductivity is achieved. Among them, the nickel-coated graphite powder forms a dense nickel metal layer on the surface of the graphite powder through a chemical nickel plating process. This metal layer not only gives the graphite powder excellent conductivity, but also improves its oxidation resistance and chemical stability. The conductivity of the nickel-coated graphite powder mainly comes from the high conductivity of the nickel layer and the conductivity of the graphite itself. The synergistic effect of the two makes the composite material perform well in conductivity. Therefore, the addition of nickel-coated graphite powder makes the composite plastic product have excellent conductivity and electromagnetic shielding function.

[0033] Specifically, after adding quaternary ammonium salt, phosphorus flame retardant and antioxidant to the continuous glass fiber and glass fiber fabric in S3, the stirring speed is 200-400 rpm, the stirring time is 5-10 minutes, and the solution temperature is maintained at 75-80° C. to ensure that the two glass fibers are fully mixed.

[0034] The advantages are: the present invention achieves the beneficial effect of improving the flame retardant properties of composite plastic products by using a phosphorus-based flame retardant in conjunction with a modified phenolic resin, wherein the phosphorus-based flame retardant can promote the formation of a dense carbon layer in the base material during the combustion process, and this carbon layer can effectively isolate oxygen and heat, preventing the flame from further spreading, thereby playing a flame retardant role; and the modified phenolic resin has high thermal stability, can maintain structural integrity at high temperatures, will not easily decompose or burn, provides a heat-resistant foundation for the composite material, and helps to improve the overall flame retardant properties; the synergistic effect of the phosphorus-based flame retardant and the modified phenolic resin can improve the flame retardant grade and oxygen index of the composite plastic product, and ultimately improve the flame retardant properties of the composite plastic product.

[0035] Specifically, the extrusion molding conditions in S4 are as follows: the temperature of the front section of the extruder is controlled at 160-165°C, the temperature of the middle section is controlled at 195-200°C, the temperature of the rear section is controlled at 215-220°C, and the screw speed is controlled at 45-50r / min, so that the resin fully impregnates the glass fiber and is molded into the desired product shape.

[0036] Specifically, the raw materials of the composite plastic product and their mass parts include: 45 parts of epoxy resin; 38 parts of modified phenolic resin; 25 parts of unsaturated polyester resin; 29 parts of continuous glass fiber; 20 parts of glass fiber fabric; 3 parts of diethylenetriamine; 9 parts of methylhexahydrophthalic anhydride; 7 parts of styrene-butadiene rubber; 5 parts of nano-silica; 0.8 parts of quaternary ammonium salt; 3 parts of nickel-coated graphite powder; 10 parts of phosphorus-based flame retardant; 0.4 parts of antioxidant; and 0.9 parts of silane coupling agent.

[0037] The raw materials of the composite plastic product and their weight parts include: 44-50 parts of epoxy resin; 35-42 parts of modified phenolic resin; 20-30 parts of unsaturated polyester resin; 26-33 parts of continuous glass fiber; 18-24 parts of glass fiber fabric; 2-4 parts of diethylenetriamine; 7-11 parts of methylhexahydrophthalic anhydride; 6-8 parts of styrene-butadiene rubber; 3-7 parts of nano-silicon dioxide; 0.6-0.9 parts of quaternary ammonium salt; 2-5 parts of nickel-coated graphite powder; 7-12 parts of phosphorus flame retardant; 0.2-0.6 parts of antioxidant; and 0.5-1.2 parts of silane coupling agent.

[0038] According to the raw material formula range of the composite plastic product of the present invention, Examples 1-3 with different proportions were prepared, and then the raw material formula of the composite plastic product of the present invention was deleted, added or replaced to obtain Comparative Examples 1-3, whose formulas are shown in Table 1 below: Table 1 Raw material name Example 1 Example 2 Example 3 Comparative Example 1 (Non-nickel coated graphite) Comparative Example 2 (Ordinary Graphite) Comparative Example 3 (Phosphorus-free flame retardant) Resin matrix - - - - - - epoxy resin 46 50 44 48 47 45 Modified phenolic resin 38 35 42 40 38 41 Unsaturated polyester resin 25 30 20 22 28 24 Reinforcement materials - - - - - - Continuous glass fiber 30 26 33 28 31 29 fiberglass fabric 20 24 18 22 19 21 Excipients and additives - - - - - - diethylenetriamine 6 5 8 7 6 6 Methylhexahydrophthalic anhydride 6 8 4 5 7 5 Styrene-butadiene rubber 8 6 10 7 9 8 Nanosilica 7 5 10 6 7 8 Quaternary ammonium salts 2 1 3 2 1.5 2.5 Nickel coated graphite powder 4 3 5 0 Ordinary graphite powder 4 4 Phosphorus flame retardants 7 8 5 6 7 0 antioxidants 0.8 0.5 1 0.7 0.6 0.9 Silane coupling agent 1 0.5 1.5 0.8 1.2 1 The examples and comparative examples were made into composite plastic products according to the preparation method of the present invention, and performance tests were performed. The performance test data are shown in Table 2 below: Table 2 Test items Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Mechanical properties - - - - - - Tensile strength (MPa) 325 310 340 280 295 305 Flexural strength (MPa) 285 270 300 240 255 260 Impact strength (kJ / m²) 45 38 50 32 35 40 Functional - - - - - - Flame retardant grade V-0 V-0 V-1 V-1 V-2 HB Volume resistivity (Ω·cm) <![CDATA[10 5 ]]> <![CDATA[10 6 ]]> <![CDATA[10 4 ]]> 10¹² <![CDATA[10 8 ]]> <![CDATA[10 5 ]]> Electromagnetic shielding effectiveness (dB) 45 38 50 5 15 42 Thermal performance - - - - - - Heat deformation temperature (℃) 185 175 195 170 180 178 Oxygen index (%) 32 30 28 26 25 20 According to Table 1-2 above, the electromagnetic shielding effectiveness of the finished product of Comparative Example 1 (graphite without nickel coating) is significantly reduced (45→5dB), and the conductivity is poor (resistivity increases to 10 12 Ω·cm), thus verifying that the nickel-coated graphite in the embodiment of the present invention has conductive / electromagnetic shielding functions; in Comparative Example 2, the nickel-coated graphite powder is replaced with ordinary graphite powder, and the electromagnetic shielding effectiveness of the finished product is 15 dB, which is lower than the electromagnetic shielding effectiveness range of 38-50 dB of the finished product in the embodiment, indicating that the surface metallization treatment of the nickel-coated graphite is more effective in improving the conductivity of the finished product; in Comparative Example 3, there is no phosphorus-based flame retardant, and its flame retardant grade is reduced to HB, and the oxygen index is only 20%, proving that the synergistic effect of the phosphorus-based flame retardant and the modified phenolic resin can improve the flame retardant properties of the finished product.

[0039] Summary: By rationally proportioning epoxy resin, modified phenolic resin and unsaturated polyester resin, a foundation of excellent comprehensive resin performance is provided. By introducing continuous glass fiber and glass fiber fabric as reinforcing materials, the overall strength and toughness of the material are further improved, so that the prepared composite plastic products have the advantages of good conductivity, high electromagnetic shielding efficiency, strong flame retardant properties, excellent mechanical properties and good thermal stability.

[0040] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a functional glass fiber reinforced composite plastic product, characterized in that: The following steps are involved: S1. Prepare raw materials: prepare epoxy resin, modified phenolic resin, unsaturated polyester resin, continuous glass fiber, glass fiber fabric, diethylenetriamine, methylhexahydrophthalic anhydride, styrene-butadiene rubber, nano-silica, quaternary ammonium salt, nickel-coated graphite powder, phosphorus-based flame retardant, antioxidant and silane coupling agent as raw materials according to the formula ratio; S2, raw material pretreatment stage: soaking the continuous glass fiber and glass fiber fabric in a silane coupling agent, premixing the epoxy resin with diethylenetriamine, premixing the modified phenolic resin with methylhexahydrophthalic anhydride, and premixing the unsaturated polyester resin with styrene-butadiene rubber; S3, blending stage: After blending the pretreated epoxy resin, modified phenolic resin and unsaturated polyester resin, nano-silica and nickel-coated graphite powder are added to obtain a resin system; after blending the pretreated continuous glass fiber and glass fiber fabric, quaternary ammonium salt, phosphorus-based flame retardant and antioxidant are added to obtain a glass fiber system; S4. Extrusion molding: The resin system and the glass fiber system are mixed through an extruder, and after three temperature-controlled molding, a preliminarily formed composite plastic product is obtained.

2. The method for preparing a functional glass fiber reinforced composite plastic product according to claim 1, characterized in that: The raw materials of the composite plastic product and their weight parts include: 44-50 parts of epoxy resin; 35-42 parts of modified phenolic resin; 20-30 parts of unsaturated polyester resin; 26-33 parts of continuous glass fiber; 18-24 parts of glass fiber fabric; 2-4 parts of diethylenetriamine; 7-11 parts of methylhexahydrophthalic anhydride; 6-8 parts of styrene-butadiene rubber; 3-7 parts of nano-silicon dioxide; 0.6-0.9 parts of quaternary ammonium salt; 2-5 parts of nickel-coated graphite powder; 7-12 parts of phosphorus flame retardant; 0.2-0.6 parts of antioxidant; and 0.5-1.2 parts of silane coupling agent.

3. The method for preparing a functional glass fiber reinforced composite plastic product according to claim 1, characterized in that: The unsaturated polyester resin is prepared from maleic anhydride, phthalic anhydride, ethylene glycol and p-toluenesulfonic acid (as a catalyst), and its chemical reaction formula is: nHO-R-OH+mC=O→Polyester chain+H2O In the reaction formula, R is a diol alkyl chain, and the dotted box is a mixed anhydride of maleic anhydride and phthalic anhydride.

4. The method for preparing a functional glass fiber reinforced composite plastic product according to claim 1, characterized in that: The nickel-coated graphite powder preparation process is as follows: S1.

1. Graphite powder pretreatment: Graphite powder is ultrasonically cleaned with 60% to 65% concentrated nitric acid for 25-30 minutes. During this process, the concentrated nitric acid reacts with impurities on the graphite surface to produce carbon dioxide, nitrogen dioxide, and water. S1.2, Sensitization treatment: Immerse the pretreated graphite powder in SnCl2·2H2O solution and stir at room temperature for 30 minutes to allow the surface to adsorb Sn. 2+ , stannous chloride dissociates in water, causing Sn to be adsorbed on the graphite surface 2+ ; S1.3, activation treatment: the sensitized graphite powder is transferred into PdCl2 solution and stirred for 8-10 minutes to induce the formation of Pd catalytic active sites on the surface. The palladium ions are adsorbed and reduced to metallic palladium. At the same time, Sn 2+ Oxidized to Sn 4+ ; S1.4, Chemical Nickel Plating: Prepare a plating solution with a pH of 4.45-4.55 by adding 20 g / L NiSO4·6H2O, 25 g / L sodium hypophosphite, and 15 g / L sodium citrate. Heat to 80-85°C, add activated graphite powder, and mechanically stir under nitrogen protection. Allow to react for 2-2.15 hours. Nickel will be deposited on the graphite surface. The hypophosphite will reduce the nickel ions to metallic nickel and will be oxidized to phosphite. The chemical reaction formula is: <h2 style=";text-align:left;direction:ltr">Ni<h2 style=";text-align:left;direction:ltr"> 2+ <h2 style=";text-align:left;direction:ltr"> +H2PO<h2 style=";text-align:left;direction:ltr"> 2− <h2 style=";text-align:left;direction:ltr"> +H2O→Ni↓+H2PO<h2 style=";text-align:left;direction:ltr"> 3− <h2 style=";text-align:left;direction:ltr"> +2H<h2 style=";text-align:left;direction:ltr"> + In the reaction formula, sodium citrate stabilizes the plating solution through complexation and does not participate in the redox reaction. Nitrogen protection prevents oxidation side reactions. S1.

5. Post-treatment: The reaction product in S1.4 is washed with ethanol 3-8 times, and then dried under vacuum at 55-60° C. for 1.5-2 h to obtain nickel-coated graphite powder.

5. The method for preparing a functional glass fiber reinforced composite plastic product according to claim 1, characterized in that: The epoxy resin, modified phenolic resin and unsaturated polyester resin constitute the matrix resin; the continuous glass fiber and glass fiber fabric constitute the reinforcing material; the diethylenetriamine and methylhexahydrophthalic anhydride constitute the curing agent, and the styrene-butadiene rubber is a toughening agent; the nano-silica, quaternary ammonium salt, nickel-coated graphite powder and phosphorus-based flame retardant constitute the functional additives, and the antioxidant and silane coupling agent constitute the auxiliary agent.

6. The method for preparing a functional glass fiber reinforced composite plastic product according to claim 1, characterized in that: The raw material pretreatment conditions in S2 are: S2.

1. Soak the continuous glass fiber and glass fiber fabric in a silane coupling agent for 1-2 hours, remove and rinse 2-4 times, and then dry at 55-60°C for 30-40 minutes. S2.

2. Pre-react epoxy resin and diethylenetriamine in a water bath at 50-55°C for 8-12 minutes; S2.

3. Premix the modified phenolic resin and methyl hexahydrophthalic anhydride in a water bath at 75-80°C and homogenize for 30-45 minutes; S2.

4. Blend the unsaturated polyester resin and styrene-butadiene rubber at room temperature for 25-30 minutes.

7. The method for preparing a functional glass fiber reinforced composite plastic product according to claim 1, characterized in that: The epoxy resin, modified phenolic resin and unsaturated polyester resin in S3 are mixed with nano-silica and nickel-coated graphite powder and stirred at a speed of 500-600 r / min for 10-15 minutes. After stirring for 5-6 minutes, the solution temperature is raised to 125-130° C. to obtain a resin system. The resin system is then transferred to a vacuum degassing device, the vacuum degree is controlled at -0.09 to -0.1 MPa, and the degassing time is 10-15 minutes.

8. The method for preparing a functional glass fiber reinforced composite plastic product according to claim 1, characterized in that: After adding the quaternary ammonium salt, phosphorus flame retardant and antioxidant, the continuous glass fiber and glass fiber fabric in S3 are stirred at a speed of 200-400 rpm for 5-10 min, and the solution temperature is maintained at 75-80°C.

9. The method for preparing a functional glass fiber reinforced composite plastic product according to claim 1, characterized in that: The extrusion molding conditions in S4 are as follows: the temperature of the front section of the extruder is controlled at 160-165°C, the temperature of the middle section is controlled at 195-200°C, the temperature of the rear section is controlled at 215-220°C, and the screw speed is controlled at 45-50 r / min.

10. The method for preparing a functional glass fiber reinforced composite plastic product according to claim 1, characterized in that: The raw materials of the composite plastic product and their weight parts include: 45 parts of epoxy resin; 38 parts of modified phenolic resin; 25 parts of unsaturated polyester resin; 29 parts of continuous glass fiber; 20 parts of glass fiber fabric; 3 parts of diethylenetriamine; 9 parts of methylhexahydrophthalic anhydride; 7 parts of styrene-butadiene rubber; 5 parts of nano-silicon dioxide; 0.8 parts of quaternary ammonium salt; 3 parts of nickel-coated graphite powder; 10 parts of phosphorus flame retardant; 0.4 parts of antioxidant; and 0.9 parts of silane coupling agent.

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