A method for preparing glass fiber reinforced plastic

Abstract

The invention relates to the field of composite materials, and in particular to a method for preparing glass fiber reinforced plastics, which is used to solve the problem that the existing glass fiber reinforced PLA plastics are prone to softening and degradation of polymer matrix, cracking of matrix, debonding of glass fiber and matrix under high temperature conditions, and even the problem that the glass fiber reinforced PLA plastics have poor performance in fire due to the inherent flammability of PLA plastics. In the preparation method, modified glass fiber is added to PLA resin, and the modified glass fiber has excellent mechanical properties and good compatibility and bonding with PLA resin, so that the excellent properties of glass fiber can be fully exerted in plastics, thereby greatly improving the mechanical properties of plastic materials. At the same time, a modified additive is added to the PLA resin, and the modified additive has excellent flame retardant properties, so that the plastic material has excellent flame retardant properties, and the fire risk is effectively reduced.

Description

Technical Field

[0001] The invention relates to the field of composite materials, and in particular to a method for preparing glass fiber reinforced plastics. Background Art

[0002] Glass fiber reinforced polymer composites have the advantages of low density, high specific stiffness and specific strength, good fatigue resistance, good corrosion resistance, low thermal expansion rate, etc., and are widely used in the fields of automobiles, aerospace, ships, civil infrastructure, etc. With the enhancement of environmental awareness, the research and application of degradable plastics have gradually received attention. PLA plastic, as a plastic with good biodegradability, has a wide range of applications.

[0003] However, glass fiber reinforced PLA plastics are prone to softening and degradation of the polymer matrix, cracking of the matrix, and debonding of the glass fiber and the matrix under high temperature conditions. As the glass fiber reinforced PLA plastics are exposed to thermal radiation for a longer time, the composite material begins to lose strength. Even due to the inherent flammability of PLA plastics, glass fiber reinforced PLA plastics perform poorly in fires, which seriously limits their application in fields that require high flame retardancy and mechanical properties. Therefore, it is of great practical significance to develop a method for preparing glass fiber reinforced plastics with excellent biodegradability, mechanical properties, high temperature resistance and flame retardancy. Summary of the invention

[0004] In order to overcome the above technical problems, the purpose of the present invention is to provide a method for preparing glass fiber reinforced plastics: PLA resin, modified glass fiber, modified additives, antioxidants, plasticizers and ultraviolet absorbers are added to a mixer and mixed evenly to obtain a mixture, and the mixture is added to a twin-screw extruder for melt extrusion to obtain glass fiber reinforced plastics, thereby solving the problems that the existing glass fiber reinforced PLA plastics are prone to softening and degradation of the polymer matrix, cracking of the matrix, and debonding of the glass fiber and the matrix under high temperature conditions, and even the problem that the glass fiber reinforced PLA plastics perform poorly in fire due to the inherent flammability of the PLA plastics.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A method for preparing glass fiber reinforced plastics comprises the following steps:

[0007] Step 1: weigh 80-90 parts of PLA resin, 12-24 parts of modified glass fiber, 2.5-7.5 parts of modified additive, 1-3 parts of antioxidant, 0.5-1.5 parts of plasticizer and 0.3-0.9 parts of ultraviolet absorber according to weight parts, and set aside;

[0008] Step 2: Add PLA resin, modified glass fiber, modified additive, antioxidant, plasticizer and ultraviolet absorber into a mixer and mix them evenly to obtain a mixture;

[0009] Step 3: Add the mixed material into a twin-screw extruder for melt extrusion to obtain glass fiber reinforced plastic.

[0010] As a further solution of the present invention: the modified glass fiber is prepared by the following steps:

[0011] Step a1: adding glass fiber into a muffle furnace, calcining at a temperature of 600-620° C. for 30-40 min, cooling with the furnace, washing with distilled water for 3-5 times, and then placing in a vacuum drying oven, drying at a temperature of 80-85° C. for 1.5-2 h to obtain calcined glass fiber;

[0012] Step a2: Add toluene diisocyanate, silane coupling agent, deionized water and anhydrous ethanol into a three-necked flask equipped with a stirrer and a thermometer, stir and react for 30-50 minutes at a temperature of 25-30°C and a stirring rate of 400-500r / min, then add calcined glass fiber and continue stirring and reacting for 8-10 hours at a temperature of 80-85°C. After the reaction is completed, cool the reaction product to room temperature, vacuum filter it, wash the filter cake with distilled water for 3-5 times, and then place it in a vacuum drying oven and dry it at a temperature of 60-65°C for 3-4 hours to obtain modified glass fiber.

[0013] As a further solution of the present invention: the PLA resin is Thailand Total PLA polylactic acid L175.

[0014] As a further solution of the present invention: the antioxidant is one of antioxidant 1010, antioxidant 1076 and antioxidant 1024.

[0015] As a further solution of the present invention: the plasticizer is one of diisobutyl phthalate, dibutyl phthalate and diethyl phthalate.

[0016] As a further solution of the present invention: the ultraviolet absorber is one of the ultraviolet absorber UV-P, ultraviolet absorber UV-531 and ultraviolet absorber UVP-327.

[0017] As a further solution of the present invention: the length of the glass fiber in step a1 is 2-5 mm.

[0018] As a further solution of the present invention: the usage ratio of the toluene diisocyanate, silane coupling agent, deionized water, anhydrous ethanol and calcined glass fiber in step a2 is 1-1.5g:5-9g:20-25mL:100-120mL:10g.

[0019] As a further solution of the present invention: the silane coupling agent in step a2 is silane coupling agent KH-550.

[0020] As a further solution of the present invention: the modified additive is prepared by the following steps:

[0021] Step b1: Add 4-(2-hydroxyethyl)benzaldehyde, triethylamine and dichloromethane to a three-necked flask equipped with a stirrer, a thermometer and a constant pressure dropping funnel, stir and react for 20-30 minutes at a temperature of 25-30°C and a stirring rate of 400-500r / min, then add dichlorophosphate phenyl ester solution dropwise while stirring, and control the dropping rate to 1-2 drops / s. After the addition is completed, continue to stir and react for 2-3 hours, then heat to 60-65°C and continue to stir and react for 2-3 hours. After the reaction is completed, cool the reaction product to room temperature, then vacuum filter, and rotary evaporate the filtrate to remove the solvent to obtain intermediate 1;

[0022] Step b2: Add intermediate 1, melamine, anhydrous sodium acetate and anhydrous ethanol into a three-necked flask equipped with a stirrer, a thermometer, an air guide tube and a reflux condenser, introduce nitrogen protection, stir and react for 20-30 minutes at a temperature of 25-30° C. and a stirring rate of 400-500 r / min, then heat to reflux and continue stirring and reacting for 4-5 hours. After the reaction is completed, cool the reaction product to room temperature, then vacuum filter, and rotary evaporate the filtrate to remove the solvent to obtain intermediate 2;

[0023] Step b3: Add intermediate 2, DOPO and anhydrous ethanol to a three-necked flask equipped with a stirrer, a thermometer, an air duct and a reflux condenser, introduce nitrogen protection, stir the reaction at a temperature of 25-30°C and a stirring rate of 400-500r / min for 5-10min, then raise the temperature to reflux and continue stirring the reaction for 8-10h. After the reaction is completed, the reaction product is cooled to room temperature, then vacuum filtered, and the filtrate is rotary evaporated to remove the solvent to obtain a modified additive.

[0024] As a further scheme of the present invention: the usage ratio of the 4-(2-hydroxyethyl)benzaldehyde, triethylamine, dichloromethane and dichlorophenyl phosphate solution in step b1 is 22-25mmol:25-30mmol:80-85mL:50-55mL.

[0025] As a further solution of the present invention: the dichlorophenyl phosphate solution in step b2 is a solution formed by dissolving dichlorophenyl phosphate in dichloromethane at a ratio of 2 mmol:10 mL.

[0026] As a further solution of the present invention: the usage ratio of the intermediate 1, melamine, anhydrous sodium acetate and anhydrous ethanol in step b2 is 10 mmol: 21-23 mmol: 0.03-0.05 g: 50-55 mL.

[0027] As a further solution of the present invention: the usage ratio of the intermediate 2, DOPO and anhydrous ethanol in step b3 is 10 mmol: 20 mmol: 80-85 mL.

[0028] Beneficial effects of the present invention:

[0029] The invention discloses a method for preparing glass fiber reinforced plastics. The method comprises the following steps: adding PLA resin, modified glass fiber, modified additive, antioxidant, plasticizer and ultraviolet absorber into a mixer and mixing them evenly to obtain a mixture; and adding the mixture into a twin-screw extruder for melt extrusion to obtain glass fiber reinforced plastics. In the preparation method, modified glass fiber is added into PLA resin, and the modified glass fiber has excellent mechanical properties and good compatibility and bonding force with PLA resin, so that the two can be closely combined, so that the excellent properties of glass fiber can be fully exerted in plastics, thereby greatly improving the mechanical properties of plastic materials. Meanwhile, modified additive is added into PLA resin, and the modified additive has excellent flame retardant properties, so that the plastic materials have excellent flame retardant properties, and the fire risk is effectively reduced.

[0030] In the process of preparing glass fiber reinforced plastics, a modified glass fiber is first prepared. First, the glass fiber is calcined to remove the sizing agent on the surface to obtain calcined glass fiber. Then, the calcined glass fiber is modified by toluene diisocyanate and silane coupling agent to obtain modified glass fiber. The glass fiber itself has excellent mechanical properties, such as high strength and high stiffness. Adding it to PLA plastic can bear part of the external load, thereby improving the overall strength of PLA plastic, helping to reduce the shrinkage and deformation of PLA plastic during the molding process, thereby improving its dimensional stability. Moreover, after the glass fiber is modified, the silane coupling agent can The siloxane on the crosslinking agent is hydrolyzed to form silanol, which can react with the hydroxyl group on the calcined glass fiber, and toluene diisocyanate can also react with the hydroxyl group on the calcined glass fiber, thereby introducing organic groups on the surface of the calcined glass fiber, improving the compatibility of the calcined glass fiber with PLA plastic, and also introducing amino and isocyanate groups as reactive groups, so that they can react chemically with PLA plastic, so that they are doped into the plastic matrix in the form of chemical bonds, with high bonding strength and uniform distribution, so that the excellent performance of the glass fiber can be fully exerted in the PLA plastic, and the mechanical properties of the PLA plastic are greatly improved;

[0031] In the process of preparing glass fiber reinforced plastics, a modified additive is also prepared. First, 4-(2-hydroxyethyl)benzaldehyde and dichlorophenyl phosphate are reacted, and the chlorine atom on the dichlorophenyl phosphate reacts with the hydroxyl group on the 4-(2-hydroxyethyl)benzaldehyde to undergo a nucleophilic substitution reaction, and the benzaldehyde groups are connected on both sides of the skeleton with the phenyl phosphate group as a skeleton to obtain an intermediate 1. Then, the intermediate 1 is reacted with melamine, and the aldehyde group on the intermediate 1 reacts with an amino group on the melamine to form a Schiff base structure to obtain an intermediate 2. Then, the intermediate 2 is reacted with DOPO, and the C=N on the intermediate 2 reacts with the PH on the DOPO to obtain a modified additive. The molecular structure of the modified additive contains a large number of benzene rings, which give it good thermal stability. It also contains a large amount of organic nitrogen and organic phosphorus. The organic nitrogen can decompose and release a large amount of inert gas when heated to reduce the concentration of combustible gas. The organic phosphorus decomposes when heated to form phosphoric acid and polyphosphoric acid compounds, which can promote the dehydration and carbonization of organic matter. The formed carbon layer gives it good flame retardant properties under the synergistic effect of the two. Therefore, adding the modified additive can significantly improve the flame retardant properties of PLA plastics. In addition, the modified additive contains a large amount of amino groups that can react with PLA plastics and modified glass fibers to improve the bonding strength and ensure that the mechanical properties of PLA plastics will not be reduced. DETAILED DESCRIPTION

[0032] 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.

[0033] Embodiment 1:

[0034] This embodiment is a method for preparing glass fiber reinforced plastic, comprising the following steps:

[0035] Step 1: Weigh 80 parts of PLA resin, 12 parts of modified glass fiber, 2.5 parts of modified additives, 1 part of antioxidant, 0.5 parts of plasticizer and 0.3 parts of ultraviolet absorber according to weight parts, and set aside;

[0036] The PLA resin is Total PLA polylactic acid L175 from Thailand;

[0037] The modified glass fiber is prepared by the following steps:

[0038] Step a1: adding glass fiber with a length of 2 mm into a muffle furnace, calcining at a temperature of 600° C. for 30 min, cooling with the furnace, washing with distilled water for 3 times, and then placing in a vacuum drying oven and drying at a temperature of 80° C. for 1.5 h to obtain calcined glass fiber;

[0039] Step a2: 1 g of toluene diisocyanate, 5 g of silane coupling agent KH-550, 20 mL of deionized water and 100 mL of anhydrous ethanol were added to a three-necked flask equipped with a stirrer and a thermometer, and stirred for reaction at a temperature of 25° C. and a stirring rate of 400 r / min for 30 min. Then, 10 g of calcined glass fiber was added and the temperature was raised to 80° C. and the stirring reaction was continued for 8 h. After the reaction was completed, the reaction product was cooled to room temperature, and then vacuum filtered. The filter cake was washed with distilled water 3 times, and then placed in a vacuum drying oven and dried at a temperature of 60° C. for 3 h to obtain modified glass fiber;

[0040] The modified additive is prepared by the following steps:

[0041] Step b1: Add 22mmol 4-(2-hydroxyethyl)benzaldehyde, 25mmol triethylamine and 80mL dichloromethane to a three-necked flask equipped with a stirrer, a thermometer and a constant pressure dropping funnel, stir and react for 20min at a temperature of 25°C and a stirring rate of 400r / min, then add dropwise 50mL of a dichlorophenyl phosphate solution formed by dissolving 2mmol:10mL of phenyl dichlorophosphate in dichloromethane while stirring, and control the dropping rate to 1 drop / s. After the addition is completed, continue to stir and react for 2h, then continue to stir and react for 2h under the condition of heating to 60°C. After the reaction is completed, cool the reaction product to room temperature, then vacuum filter, and rotary evaporate the filtrate to remove the solvent to obtain intermediate 1;

[0042] Step b2: 10 mmol of intermediate 1, 21 mmol of melamine, 0.03 g of anhydrous sodium acetate and 50 mL of anhydrous ethanol were added to a three-necked flask equipped with a stirrer, a thermometer, a gas guide tube and a reflux condenser, and nitrogen was introduced for protection. The mixture was stirred at 25° C. and a stirring rate of 400 r / min for 20 min, and then the temperature was raised to reflux and the stirring reaction was continued for 4 h. After the reaction was completed, the reaction product was cooled to room temperature, and then vacuum filtered, and the filtrate was rotary evaporated to remove the solvent to obtain intermediate 2;

[0043] Step b3: 10 mmol of intermediate 2, 20 mmol of DOPO and 80 mL of anhydrous ethanol were added to a three-necked flask equipped with a stirrer, a thermometer, a gas duct and a reflux condenser, and nitrogen was introduced for protection. The mixture was stirred at 25° C. and a stirring rate of 400 r / min for 5 min, and then the temperature was raised to reflux and the stirring reaction was continued for 8 h. After the reaction was completed, the reaction product was cooled to room temperature, and then vacuum filtered, and the filtrate was rotary evaporated to remove the solvent to obtain a modified additive;

[0044] The antioxidant is antioxidant 1010;

[0045] The plasticizer is diisobutyl phthalate;

[0046] The ultraviolet absorber is an ultraviolet absorber UV-P;

[0047] Step 2: Add PLA resin, modified glass fiber, modified additive, antioxidant, plasticizer and ultraviolet absorber into a mixer and mix them evenly to obtain a mixture;

[0048] Step 3: Add the mixed material into a twin-screw extruder for melt extrusion to obtain glass fiber reinforced plastic.

[0049] Embodiment 2:

[0050] This embodiment is a method for preparing glass fiber reinforced plastic, comprising the following steps:

[0051] Step 1: Weigh 85 parts of PLA resin, 18 parts of modified glass fiber, 5 parts of modified additive, 2 parts of antioxidant, 1 part of plasticizer and 0.6 parts of ultraviolet absorber according to weight parts, and set aside;

[0052] The PLA resin is Total PLA polylactic acid L175 from Thailand;

[0053] The modified glass fiber is prepared by the following steps:

[0054] Step a1: adding glass fiber with a length of 3 mm into a muffle furnace, calcining at a temperature of 610° C. for 35 min, cooling with the furnace, washing with distilled water for 4 times, and then placing in a vacuum drying oven and drying at a temperature of 82° C. for 1.8 h to obtain calcined glass fiber;

[0055] Step a2: 1.2 g toluene diisocyanate, 7 g silane coupling agent KH-550, 22 mL deionized water and 110 mL anhydrous ethanol were added to a three-necked flask equipped with a stirrer and a thermometer, and stirred for reaction at a temperature of 28° C. and a stirring rate of 450 r / min for 40 min, then 10 g calcined glass fiber was added and the temperature was raised to 82° C. and the stirring reaction was continued for 9 h. After the reaction was completed, the reaction product was cooled to room temperature, and then vacuum filtered. The filter cake was washed with distilled water 4 times, and then placed in a vacuum drying oven and dried at a temperature of 62° C. for 3.5 h to obtain modified glass fiber;

[0056] The modified additive is prepared by the following steps:

[0057] Step b1: 23mmol 4-(2-hydroxyethyl)benzaldehyde, 28mmol triethylamine and 82mL dichloromethane were added to a three-necked flask equipped with a stirrer, a thermometer and a constant pressure dropping funnel, and stirred for 25min at a temperature of 28°C and a stirring rate of 450r / min, and then 52mL dichlorophenyl phosphate was added dropwise while stirring. The dichlorophenyl phosphate solution was formed by dissolving 2mmol:10mL of phenyl dichlorophosphate in dichloromethane, and the dropping rate was controlled to be 1 drop / s. After the addition was completed, the stirring reaction was continued for 2.5h, and then the temperature was raised to 62°C and the stirring reaction was continued for 2.5h. After the reaction was completed, the reaction product was cooled to room temperature, and then vacuum filtered, and the filtrate was rotary evaporated to remove the solvent to obtain intermediate 1;

[0058] Step b2: 10 mmol of intermediate 1, 22 mmol of melamine, 0.04 g of anhydrous sodium acetate and 52 mL of anhydrous ethanol were added to a three-necked flask equipped with a stirrer, a thermometer, a gas guide tube and a reflux condenser, and nitrogen was introduced for protection. The mixture was stirred for reaction at 28° C. and a stirring rate of 450 r / min for 25 min, and then the temperature was raised to reflux and the stirring reaction was continued for 4.5 h. After the reaction was completed, the reaction product was cooled to room temperature, and then vacuum filtered, and the filtrate was rotary evaporated to remove the solvent to obtain intermediate 2;

[0059] Step b3: 10 mmol of intermediate 2, 20 mmol of DOPO and 82 mL of anhydrous ethanol were added to a three-necked flask equipped with a stirrer, a thermometer, an air guide tube and a reflux condenser, and nitrogen was introduced for protection. The reaction was stirred at 28° C. and a stirring rate of 450 r / min for 8 min, and then the temperature was raised to reflux and the stirring reaction was continued for 9 h. After the reaction was completed, the reaction product was cooled to room temperature, and then vacuum filtered, and the filtrate was rotary evaporated to remove the solvent to obtain a modified additive;

[0060] The antioxidant is antioxidant 1076;

[0061] The plasticizer is dibutyl phthalate;

[0062] The ultraviolet absorber is ultraviolet absorber UV-531;

[0063] Step 2: Add PLA resin, modified glass fiber, modified additive, antioxidant, plasticizer and ultraviolet absorber into a mixer and mix them evenly to obtain a mixture;

[0064] Step 3: Add the mixed material into a twin-screw extruder for melt extrusion to obtain glass fiber reinforced plastic.

[0065] Embodiment 3:

[0066] This embodiment is a method for preparing glass fiber reinforced plastic, comprising the following steps:

[0067] Step 1: Weigh 90 parts of PLA resin, 24 parts of modified glass fiber, 7.5 parts of modified additive, 3 parts of antioxidant, 1.5 parts of plasticizer and 0.9 parts of ultraviolet absorber according to weight parts, and set aside;

[0068] The PLA resin is Total PLA polylactic acid L175 from Thailand;

[0069] The modified glass fiber is prepared by the following steps:

[0070] Step a1: adding a glass fiber with a length of 5 mm into a muffle furnace, calcining it at a temperature of 620° C. for 40 min, cooling it with the furnace, washing it with distilled water for 5 times, and then placing it in a vacuum drying oven and drying it at a temperature of 85° C. for 2 h to obtain a calcined glass fiber;

[0071] Step a2: 1.5 g of toluene diisocyanate, 9 g of silane coupling agent KH-550, 25 mL of deionized water and 120 mL of anhydrous ethanol were added to a three-necked flask equipped with a stirrer and a thermometer, and stirred for reaction at a temperature of 30° C. and a stirring rate of 500 r / min for 50 min, then 10 g of calcined glass fiber was added and the temperature was raised to 85° C. and the stirring reaction was continued for 10 h. After the reaction was completed, the reaction product was cooled to room temperature, and then vacuum filtered. The filter cake was washed with distilled water for 5 times, and then placed in a vacuum drying oven and dried at a temperature of 65° C. for 4 h to obtain modified glass fiber;

[0072] The modified additive is prepared by the following steps:

[0073] Step b1: Add 25mmol 4-(2-hydroxyethyl)benzaldehyde, 30mmol triethylamine and 85mL dichloromethane to a three-necked flask equipped with a stirrer, a thermometer and a constant pressure dropping funnel, stir and react for 30min at a temperature of 30°C and a stirring rate of 500r / min, then add dropwise 55mL of a dichlorophenyl phosphate solution formed by dissolving 2mmol:10mL of phenyl dichlorophosphate in dichloromethane while stirring, control the dropping rate to 2 drops / s, continue to stir and react for 3h after the dropwise addition is completed, then continue to stir and react for 3h under the condition of heating to 65°C, after the reaction is completed, cool the reaction product to room temperature, then vacuum filter, and rotary evaporate the filtrate to remove the solvent to obtain intermediate 1;

[0074] Step b2: 10 mmol of intermediate 1, 23 mmol of melamine, 0.05 g of anhydrous sodium acetate and 55 mL of anhydrous ethanol were added to a three-necked flask equipped with a stirrer, a thermometer, a gas guide tube and a reflux condenser, and nitrogen was introduced for protection. The mixture was stirred at a temperature of 30° C. and a stirring rate of 500 r / min for 30 min, and then the temperature was raised to reflux and the stirring reaction was continued for 5 h. After the reaction was completed, the reaction product was cooled to room temperature, and then vacuum filtered, and the filtrate was rotary evaporated to remove the solvent to obtain intermediate 2;

[0075] Step b3: 10 mmol of intermediate 2, 20 mmol of DOPO and 85 mL of anhydrous ethanol were added to a three-necked flask equipped with a stirrer, a thermometer, an air guide tube and a reflux condenser, and nitrogen was introduced for protection. The reaction was stirred at a temperature of 30° C. and a stirring rate of 500 r / min for 10 min, and then the temperature was raised to reflux and the stirring reaction was continued for 10 h. After the reaction was completed, the reaction product was cooled to room temperature, and then vacuum filtered, and the filtrate was rotary evaporated to remove the solvent to obtain a modified additive;

[0076] The antioxidant is antioxidant 1024;

[0077] The plasticizer is diethyl phthalate;

[0078] The ultraviolet absorber is ultraviolet absorber UVP-327;

[0079] Step 2: Add PLA resin, modified glass fiber, modified additive, antioxidant, plasticizer and ultraviolet absorber into a mixer and mix them evenly to obtain a mixture;

[0080] Step 3: Add the mixed material into a twin-screw extruder for melt extrusion to obtain glass fiber reinforced plastic.

[0081] Comparative Example 1:

[0082] This comparative example is a method for preparing a glass fiber reinforced plastic, comprising the following steps:

[0083] Step 1: Weigh 90 parts of PLA resin, 24 parts of glass fiber, 3 parts of antioxidant, 1.5 parts of plasticizer and 0.9 parts of ultraviolet absorber according to weight and set aside;

[0084] The PLA resin is Total PLA polylactic acid L175 from Thailand;

[0085] The antioxidant is antioxidant 1024;

[0086] The plasticizer is diethyl phthalate;

[0087] The ultraviolet absorber is ultraviolet absorber UVP-327;

[0088] Step 2: Add PLA resin, glass fiber, antioxidant, plasticizer and ultraviolet absorber into a mixer and mix them evenly to obtain a mixture;

[0089] Step 3: Add the mixed material into a twin-screw extruder for melt extrusion to obtain glass fiber reinforced plastic.

[0090] Comparative Example 2:

[0091] This comparative example is a method for preparing a glass fiber reinforced plastic, comprising the following steps:

[0092] Step 1: Weigh 90 parts of PLA resin, 24 parts of modified glass fiber, 3 parts of antioxidant, 1.5 parts of plasticizer and 0.9 parts of ultraviolet absorber according to weight parts and set aside;

[0093] The PLA resin is Total PLA polylactic acid L175 from Thailand;

[0094] The modified glass fiber is prepared by the following steps:

[0095] Step a1: adding a glass fiber with a length of 5 mm into a muffle furnace, calcining it at a temperature of 620° C. for 40 min, cooling it with the furnace, washing it with distilled water for 5 times, and then placing it in a vacuum drying oven and drying it at a temperature of 85° C. for 2 h to obtain a calcined glass fiber;

[0096] Step a2: 1.5 g of toluene diisocyanate, 9 g of silane coupling agent KH-550, 25 mL of deionized water and 120 mL of anhydrous ethanol were added to a three-necked flask equipped with a stirrer and a thermometer, and stirred for reaction at a temperature of 30° C. and a stirring rate of 500 r / min for 50 min, then 10 g of calcined glass fiber was added and the temperature was raised to 85° C. and the stirring reaction was continued for 10 h. After the reaction was completed, the reaction product was cooled to room temperature, and then vacuum filtered. The filter cake was washed with distilled water for 5 times, and then placed in a vacuum drying oven and dried at a temperature of 65° C. for 4 h to obtain modified glass fiber;

[0097] The antioxidant is antioxidant 1024;

[0098] The plasticizer is diethyl phthalate;

[0099] The ultraviolet absorber is ultraviolet absorber UVP-327;

[0100] Step 2: Add PLA resin, modified glass fiber, antioxidant, plasticizer and ultraviolet absorber into a mixer and mix them evenly to obtain a mixture;

[0101] Step 3: Add the mixed material into a twin-screw extruder for melt extrusion to obtain glass fiber reinforced plastic.

[0102] Comparative Example 3:

[0103] This comparative example is a method for preparing a glass fiber reinforced plastic, comprising the following steps:

[0104] Step 1: Weigh 90 parts of PLA resin, 24 parts of glass fiber, 7.5 parts of modifying additives, 3 parts of antioxidant, 1.5 parts of plasticizer and 0.9 parts of ultraviolet absorber according to weight parts, and set aside;

[0105] The PLA resin is Total PLA polylactic acid L175 from Thailand;

[0106] The modified additive is prepared by the following steps:

[0107] Step b1: Add 25mmol 4-(2-hydroxyethyl)benzaldehyde, 30mmol triethylamine and 85mL dichloromethane to a three-necked flask equipped with a stirrer, a thermometer and a constant pressure dropping funnel, stir and react for 30min at a temperature of 30°C and a stirring rate of 500r / min, then add dropwise 55mL of a dichlorophenyl phosphate solution formed by dissolving 2mmol:10mL of phenyl dichlorophosphate in dichloromethane while stirring, control the dropping rate to 2 drops / s, continue to stir and react for 3h after the dropwise addition is completed, then continue to stir and react for 3h under the condition of heating to 65°C, after the reaction is completed, cool the reaction product to room temperature, then vacuum filter, and rotary evaporate the filtrate to remove the solvent to obtain intermediate 1;

[0108] Step b2: 10 mmol of intermediate 1, 23 mmol of melamine, 0.05 g of anhydrous sodium acetate and 55 mL of anhydrous ethanol were added to a three-necked flask equipped with a stirrer, a thermometer, a gas guide tube and a reflux condenser, and nitrogen was introduced for protection. The mixture was stirred at a temperature of 30° C. and a stirring rate of 500 r / min for 30 min, and then the temperature was raised to reflux and the stirring reaction was continued for 5 h. After the reaction was completed, the reaction product was cooled to room temperature, and then vacuum filtered, and the filtrate was rotary evaporated to remove the solvent to obtain intermediate 2;

[0109] Step b3: 10 mmol of intermediate 2, 20 mmol of DOPO and 85 mL of anhydrous ethanol were added to a three-necked flask equipped with a stirrer, a thermometer, an air guide tube and a reflux condenser, and nitrogen was introduced for protection. The reaction was stirred at a temperature of 30° C. and a stirring rate of 500 r / min for 10 min, and then the temperature was raised to reflux and the stirring reaction was continued for 10 h. After the reaction was completed, the reaction product was cooled to room temperature, and then vacuum filtered, and the filtrate was rotary evaporated to remove the solvent to obtain a modified additive;

[0110] The antioxidant is antioxidant 1024;

[0111] The plasticizer is diethyl phthalate;

[0112] The ultraviolet absorber is ultraviolet absorber UVP-327;

[0113] Step 2: Add PLA resin, glass fiber, modification additive, antioxidant, plasticizer and ultraviolet absorber into a mixer and mix them evenly to obtain a mixture;

[0114] Step 3: Add the mixed material into a twin-screw extruder for melt extrusion to obtain glass fiber reinforced plastic.

[0115] The glass fiber reinforced plastics of Examples 1-3 and Comparative Examples 1-3 were subjected to performance tests, and the thermal stability of the products was analyzed using a TGA800 thermogravimetric analyzer. The sample mass was 5 mg, and the test results were the initial thermal weight loss temperature T 5％ ; According to ISO4589-2, the limiting oxygen index was measured, and the sample size was 100mm×6.5mm×3mm; according to GB / T 2048-2008, the UL94 flame retardant grade was measured, and the sample size was 130mm×13mm×3mm; according to GB / T1040.1-2018, the tensile strength was tested, and the tensile rate was 50mm / min;

[0116] The test results are shown in the following table:

[0117] sample <![CDATA[T 5％ ,℃]]> Limiting oxygen index, % UL94 flame retardant grade <![CDATA[Tensile strength, MPa > Example 1 331 41 V-0 58.3 Example 2 336 44 V-0 64.1 Example 3 340 46 V-0 69.7 Comparative Example 1 275 31 V-2 53.4 Comparative Example 2 288 35 V-1 61.8 Comparative Example 3 333 43 V-0 57.2

[0118] Referring to the data in the above table, based on the comparison between Examples 1-3 and Comparative Examples 1-3, it can be known that adding the modified glass fiber obtained after modification can greatly improve the mechanical properties of the plastic compared with the glass fiber, and adding the modified additive can greatly improve the thermal stability and flame retardant properties of the plastic.

[0119] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0120] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the invention or exceed the scope defined by the claims, they shall all fall within the protection scope of the present invention.

Claims

1. A method for preparing glass fiber reinforced plastic, characterized in that: The following steps are involved: Step 1: weigh 80-90 parts of PLA resin, 12-24 parts of modified glass fiber, 2.5-7.5 parts of modified additive, 1-3 parts of antioxidant, 0.5-1.5 parts of plasticizer and 0.3-0.9 parts of ultraviolet absorber according to weight parts, and set aside; Step 2: Add PLA resin, modified glass fiber, modified additive, antioxidant, plasticizer and ultraviolet absorber into a mixer and mix them evenly to obtain a mixture; Step 3: adding the mixed material into a twin-screw extruder for melt extrusion to obtain a glass fiber reinforced plastic; Wherein, the modified glass fiber is prepared by the following steps: Step a1: adding glass fiber into a muffle furnace for calcination, then cooling with the furnace, and then washing and drying to obtain calcined glass fiber; Step a2: stirring toluene diisocyanate, silane coupling agent, deionized water and anhydrous ethanol for reaction, then adding calcined glass fiber and continuing stirring for reaction, cooling the reaction product after the reaction is completed, then vacuum filtering, washing and drying the filter cake to obtain modified glass fiber; The modified additive is prepared by the following steps: Step b1: 4-(2-hydroxyethyl)benzaldehyde, triethylamine and dichloromethane are stirred for reaction, and then dichlorophenyl phosphate solution is added dropwise while stirring. After the addition is completed, the stirring reaction is continued. After the reaction is completed, the reaction product is cooled, and then vacuum filtered, and the filtrate is rotary evaporated to obtain intermediate 1; Step b2: stirring the intermediate 1, melamine, anhydrous sodium acetate and anhydrous ethanol to react, cooling the reaction product after the reaction is completed, and then vacuum filtering, and rotary evaporating the filtrate to obtain the intermediate 2; Step b3: The intermediate 2, DOPO and anhydrous ethanol are stirred for reaction. After the reaction is completed, the reaction product is cooled, then vacuum filtered, and the filtrate is rotary evaporated to obtain a modified additive.

2. A method for preparing glass fiber reinforced plastic according to claim 1, characterized in that: The PLA resin is Thai Total PLA polylactic acid L175; The antioxidant is one of antioxidant 1010, antioxidant 1076 and antioxidant 1024; The plasticizer is one of diisobutyl phthalate, dibutyl phthalate and diethyl phthalate; The ultraviolet absorber is one of the ultraviolet absorber UV-P, the ultraviolet absorber UV-531 and the ultraviolet absorber UVP-327.

3. The method for preparing glass fiber reinforced plastic according to claim 1, characterized in that: The length of the glass fiber in step a1 is 2-5 mm.

4. The method for preparing glass fiber reinforced plastic according to claim 1, characterized in that: The usage ratio of the toluene diisocyanate, the silane coupling agent, the deionized water, the anhydrous ethanol and the calcined glass fiber in step a2 is 1-1.5 g: 5-9 g: 20-25 mL: 100-120 mL: 10 g.

5. The method for preparing glass fiber reinforced plastic according to claim 1, characterized in that: The silane coupling agent in step a2 is silane coupling agent KH-550.

6. The method for preparing glass fiber reinforced plastic according to claim 1, characterized in that: The usage ratio of the 4-(2-hydroxyethyl)benzaldehyde, triethylamine, dichloromethane and dichlorophenyl phosphate solution in step b1 is 22-25mmol:25-30mmol:80-85mL:50-55mL.

7. The method for preparing glass fiber reinforced plastic according to claim 1, characterized in that: The dichlorophenyl phosphate solution in step b2 is a solution formed by dissolving dichlorophenyl phosphate in dichloromethane at a ratio of 2 mmol:10 mL.

8. The method for preparing glass fiber reinforced plastic according to claim 1, characterized in that: The usage ratio of the intermediate 1, melamine, anhydrous sodium acetate and anhydrous ethanol in step b2 is 10mmol:21-23mmol:0.03-0.05g:50-55mL.

9. The method for preparing glass fiber reinforced plastic according to claim 1, characterized in that: The usage ratio of the intermediate 2, DOPO and anhydrous ethanol in step b3 is 10 mmol: 20 mmol: 80-85 mL.