A surface flame-retardant compatibilized glass fiber reinforced nylon composite and a method of making the same

Abstract

The application provides a surface flame-retardant compatibilized glass fiber reinforced nylon composite material and a preparation method thereof, and belongs to the technical field of modified nylon material preparation, and aims to solve the technical problems of a 'candle core effect' caused by glass fiber and poor flame-retardant property and mechanical property of a nylon composite material. The application first grafts an interface flame-retardant compatibilizer to the surface of glass fiber to prepare surface flame-retardant compatibilized glass fiber; then, the prepared surface flame-retardant compatibilized glass fiber is mixed with nylon, a flame retardant and an additive, and is extruded, granulated, injection molded to obtain a flame-retardant compatibilized glass fiber reinforced nylon composite material. The interface flame-retardant compatibilizer is grafted to the surface of the glass fiber, which can weaken the 'candle core effect', improve the interface action between the glass fiber and the nylon matrix, play a reinforcing role, improve the mechanical property and the flame-retardant property of the glass fiber reinforced nylon flame-retardant composite material, and expand the application range.

Description

Technical Field

[0001] This invention belongs to the technical field of modified nylon material preparation, and particularly relates to a surface flame-retardant and compatibilized glass fiber reinforced nylon composite material and its preparation method. Background Technology

[0002] Polyamide (PA), commonly known as nylon, is a common engineering plastic with excellent properties such as good molding and processing performance, good self-lubrication, wear resistance, and easy coloring. It is widely used in the automotive industry, electronics, and equipment manufacturing. However, nylon materials have low notched impact strength and are not flame-retardant, releasing a large amount of heat and exhibiting dripping during combustion. This limits the application of nylon materials, especially in areas where fire safety is paramount. Therefore, flame-retardant modification of nylon to meet safety requirements is essential.

[0003] Adding halogen-free flame retardants to the system is a common solution for flame-retardant nylon. Phosphorus-based flame retardants, such as aluminum diethylphosphonate, and nitrogen-based flame retardants, such as melamine cyanurate, are widely used in the flame-retardant modification of polyamide materials due to their excellent flame-retardant effect, low toxicity, low smoke, and environmental friendliness. However, the introduction of additive flame retardants often leads to the deterioration of the mechanical properties of the matrix resin, failing to meet the application requirements in machinery, electronics, and instrumentation. Fiber reinforcement is an effective method to improve the mechanical properties of composite materials. Glass fiber, with its high cost-effectiveness, is widely used in the reinforcement and modification of nylon composites. However, when glass fiber-reinforced nylon composites are exposed to sufficiently high heat radiation, the matrix in the composite material softens and degrades, cracks, and debonds from the glass fiber. The matrix around the glass fiber begins to bleed away, and the molten matrix wetting the glass fiber provides a continuous source of fuel for combustion—this is the wick effect. Therefore, the introduction of glass fiber brings new difficulties and challenges to the flame retardancy of nylon materials. Furthermore, compatibility issues between inorganic fibers, flame retardant particles, and the organic matrix can lead to uneven flame retardant dispersion and fiber / matrix interface defects, which can degrade the performance of flame-retardant modified nylon matrices. Surface modification of fiber-reinforced polymers (GF) by designing and synthesizing flame retardants with both compatibilizing and interfacial flame-retardant functions is an effective method to improve the interfacial compatibility between fibers, flame retardants, and the matrix, improve the uniformity of flame retardant particle dispersion, and enhance the mechanical properties of flame-retardant composites. Simultaneously, the interfacial flame retardant plays a role during combustion, forming a large amount of char layer on the fiber surface. This effectively blocks the adsorption, wetting, spreading, and flow of polymer melt in the interfacial region, thereby weakening or even eliminating the wick effect, significantly improving the flame-retardant effect of the composite material, and achieving high performance in flame-retardant reinforced nylon.

[0004] Patent CN111171234A discloses a polymeric flame-retardant synergistic compatibilizer. This compatibilizer is a compound containing phosphorus and having multiple anhydride reaction sites on its molecular chain. At the polymer processing temperature, the polar anhydride groups can simultaneously react with the amino groups grafted onto the glass fiber surface and the end groups of the polymer molecular chain, greatly improving the interfacial compatibility and adhesion between the polymer matrix and the glass fiber. However, this method directly adds the compatibilizer and glass fiber to the polymer matrix, resulting in random contact between the compatibilizer and glass fiber, requiring a high amount of compatibilizer, and offering limited improvement to the mechanical and flame-retardant properties of glass fiber reinforced nylon composites. Summary of the Invention

[0005] To overcome the technical problems of poor flame retardant properties and high compatibilizer content in existing glass fiber reinforced nylon, this invention provides a surface flame retardant compatibilized glass fiber reinforced nylon composite material and its preparation method. The prepared nylon composite material achieves a flame retardant UL-94 (3.2mm) V-0 rating, effectively solving the technical problems of high efficiency, halogen-free flame retardancy, and high performance of fiber-reinforced polymer flame retardant materials. The preparation method is simple to operate, does not affect the original processing technology of fiber-reinforced nylon composite materials, and can be used for large-scale production.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] A method for preparing a surface flame-retardant and compatibilized glass fiber reinforced nylon composite material involves mixing flame-retardant and compatibilized glass fiber, nylon, flame retardant and antioxidant in a mass ratio of (10-30):(40-60):(1-20):(0.1-1), and then extruding, granulating and injection molding to obtain the flame-retardant and compatibilized glass fiber reinforced nylon composite material.

[0008] The method for preparing the flame-retardant and compatibilized glass fiber reinforced nylon composite material according to claim 1 is characterized in that the method for preparing the flame-retardant and compatibilized glass fiber includes the following steps:

[0009] (1) The glass fiber was immersed in a mixed solution I consisting of silane coupling agent and solvent I, the pH of the solution was adjusted, and the silane coupling agent was used to modify the glass fiber to obtain silane coupling agent modified glass fiber.

[0010] (2) The silane coupling agent modified glass fiber is immersed in a mixed solution II composed of interfacial flame retardant compatibilizer and solvent II to carry out flame retardant compatibilizer modification treatment, and flame retardant modified glass fiber is obtained.

[0011] In step (1), the mass ratio of silane coupling agent to solvent I is 1:(3-5), and the silane coupling agent is KH550, KH560, KH570 or KH590; solvent I is composed of water and ethanol in a mass ratio of (1-2):(8-9); the temperature for silane coupling agent modification treatment is 40-90℃ and the time is 4-8h.

[0012] In step (2), the mixed solution II is prepared by mixing the interfacial flame retardant compatibilizer and solvent II at a mass ratio of 1:(70-110); solvent II is tetrahydrofuran, diethyl ether, acetone or methyl ethyl ketone; the temperature for flame retardant compatibilizer modification treatment is 50-80℃ and the time is 10-14h.

[0013] The interfacial flame retardant compatibilizer is PPC, and the structural formula of PPC is:

[0014] Preparation method of PPC: First, dichloromethane (300 mL), hydroxyethyl acrylate (11.62 g, 0.1 mol), and triethylamine (10.12 g, 0.1 mol) are added sequentially to a round-bottom flask equipped with a constant-pressure dropping funnel and a magnetic stirrer. Under a nitrogen atmosphere, the temperature is kept below 0°C, and diphenylphosphine chloride (23.66 g, 0.1 mol) is slowly added dropwise. After the addition is complete, the mixture is transferred to room temperature and reacted for 5-6 hours, with the temperature maintained at 25-35°C. After the reaction is complete, the yellow liquid is repeatedly washed with a large amount of distilled water, dried, and the solvent in the product is removed to obtain intermediate product A. Then, tetrahydrofuran (400 mL), intermediate product A (31.63 g, 0.1 mol), and maleic anhydride (9.80 g, 0.1 mol) were added sequentially to a two-necked flask equipped with a condenser. Residual air was removed from the apparatus, and azobisisobutyronitrile (0.12 g) was added as a catalyst under nitrogen atmosphere. The mixture was refluxed at 70-90 °C for 12-24 h to obtain a wine-red liquid. After removing the solvent by rotary evaporation, the wine-red liquid was washed with a large amount of diethyl ether and dried at 40-70 °C for 12-24 h to obtain the product PPC. The reaction formula is as follows:

[0015] n is an integer.

[0016] The interfacial flame retardant compatibilizer is HPC, and the structural formula of HPC is: n is an integer.

[0017] Preparation method of HPC: First, dissolve DOPO (17.28 g, 80 mmol) in 80 mL of dichloromethane, then add carbon tetrachloride (14.76 g, 96 mmol), place in an ice bath, and cool to -3 to -5 °C. Mix hydroxyethyl acrylate (11.15 g, 96 mmol) and triethylamine (9.70 g, 96 mmol), and slowly add the mixture dropwise to the DOPO solution in carbon dichloride. Stir magnetically for 2 hours. After the addition is complete, transfer the mixture to 30-50 °C and react for 12-24 hours. Wash the reaction product with water 3-8 times, dry, and rotary evaporate to obtain a white viscous liquid B. Then, tetrahydrofuran (300 mL), intermediate product B (33.01 g, 0.1 mol), and maleic anhydride (9.80 g, 0.1 mol) were added sequentially to a two-necked flask equipped with a condenser. Residual air was removed from the apparatus, and azobisisobutyronitrile (0.12 g) was added under nitrogen atmosphere. The mixture was refluxed at 60-80 °C for 12-24 h to obtain a wine-red liquid. After removing the solvent by rotary evaporation, the wine-red liquid was washed with a large amount of diethyl ether and dried at 40-60 °C for 12-24 h to obtain the product HPC. The reaction formula is as follows:

[0018]

[0019] The interfacial flame retardant compatibilizer is HDOPO, and the structural formula of HDOPO is:

[0020] Preparation method of HDOPO: Hydroxyethyl acrylate (6.47 g, 0.55 mol), DOPO (10.00 g, 0.46 mol), triethylamine (5.6 g, 0.55 mol), and dichloromethane (80 mL) were added sequentially to a single-necked flask. The mixture was reacted at 30-40℃ for 12-24 h. The reaction solution was extracted with water 3-5 times. The organic layer was collected by rotary evaporation and drying to obtain the product HDOPO. The reaction formula is as follows:

[0021]

[0022] The flame retardant is one or more of the following: aluminum hypophosphite (AIHP), aluminum diethylphosphite (ADP), melamine polyphosphate (MPP), melamine cyanurate (MCA), ammonium polyphosphate (APP), melamine (ME), or 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and its derivatives, benzoxazine containing a silane structure, and ionic liquids containing halogen-free elements such as phosphorus, nitrogen, and sulfur; the antioxidant is one or more of the following: antioxidant 1010, antioxidant 1098, and antioxidant 1076.

[0023] The extrusion granulation process parameters are as follows: extrusion temperature is 240-280℃, main screw speed is 90-130rpm, and feeding frequency is 1-4Hz.

[0024] The beneficial effects of this invention are as follows: This invention utilizes a synthesized interfacial flame retardant compatibilizer to modify the surface of glass fibers, resulting in glass fibers with surface flame retardant and compatibilizing functions. These fibers can be directly applied to the molding process of fiber-reinforced polymer composites without altering the original processing conditions of the composite material. With the same amount of interfacial flame retardant compatibilizer, grafting it onto the surface of glass fibers significantly improves the fiber / matrix interface bonding effect compared to direct addition. The charring ability of the fiber surface is significantly enhanced during combustion, achieving a synergistic enhancement between the flame retardant and mechanical properties of the composite material. This improves both the mechanical and flame retardant properties of glass fiber reinforced nylon flame retardant composites, expanding their application range.

[0025] The process for synthesizing the interfacial flame retardant compatibilizer of this invention is simple and feasible, especially since the DOPO structure used does not contain halogen elements. Furthermore, the HPC and HDOPO prepared by this invention exhibit superior mechanical properties and flame retardancy compared to PPC in nylon composites; the synthesized HPC demonstrates superior interfacial compatibilization and gas-phase flame retardant effects during material processing; and the HDOPO compatibilizer synthesis process requires only one step, making the process even simpler. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 The 1H NMR spectrum of PPC, an interfacial flame retardant compatibilizer.

[0028] Figure 2 The 1H NMR spectrum of HPC, an interfacial flame retardant compatibilizer.

[0029] Figure 3 The 1H NMR spectrum of HDOPO, an interfacial flame retardant compatibilizer.

[0030] Figure 4 The matrix interface bonding in the cross-section of the specimen after the impact test is shown in the following images: (a) PA6 / GF / FR; (b) PA6 / GF-HPC / FR; (c) PA6 / GF-HDOPO / FR; (d) PA6 / GF-PPC / FR.

[0031] Figure 5 The matrix interface bonding in the cross-section of the specimen after the impact test; (a) PA6 / GF / FR / HDOPO; (b) PA6 / GF-HDOPO / FR. Detailed Implementation

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] Example 1

[0034] A surface-retardant and compatibilized glass fiber reinforced nylon composite material is prepared by the following steps:

[0035] The first step is to synthesize the interface compatibilizer HPC. The specific preparation steps are as follows: (1) Dissolve DOPO (17.28 g, 80 mmol) in 80 mL of dichloromethane, then add carbon tetrachloride (14.76 g, 96 mmol), place in an ice bath, and cool to -3 °C. Mix hydroxyethyl acrylate (11.15 g, 96 mmol) and triethylamine (9.70 g, 96 mmol), and slowly add the mixture dropwise to the DOPO carbon dichloride solution. Stir magnetically for 2 h. After the addition is complete, transfer to 30 °C and react for 24 h. Wash the reaction product with water 5 times, dry, and rotary evaporate to obtain a white viscous liquid B.

[0036]

[0037] (2) In a two-necked flask equipped with a condenser, tetrahydrofuran (300 mL), intermediate product B (33.01 g, 0.1 mol), and maleic anhydride (9.80 g, 0.1 mol) were added in sequence. The residual air in the flask was removed, and azobisisobutyronitrile (0.12 g) was added under nitrogen atmosphere. The mixture was refluxed at 80 °C for 12 h to obtain a wine-red liquid. After removing the solvent by rotary evaporation, the wine-red liquid was washed with a large amount of diethyl ether and dried at 60 °C for 12 h to obtain HPC. Its 1H NMR spectrum is shown below. Figure 2 As shown.

[0038]

[0039] The second step involves immersing the glass fiber in a mixed solution of KH550, distilled water, and ethanol (20 parts KH550, 8 parts distilled water, and 72 parts ethanol). The pH is adjusted to 5, the temperature is set at 80°C, and the reaction time is 6 hours. Finally, the KH550-treated glass fiber is washed with distilled water and dried for later use.

[0040] The third step involves placing the KH550-treated glass fiber into a large beaker, then adding 0.6 parts of HPC and 150 parts of tetrahydrofuran to the beaker, and reacting at 60℃ for 12 hours. Finally, the flame-retardant modified glass fiber is dried and set aside for later use, designated as GF-HPC.

[0041] In the fourth step, nylon 6, flame-retardant modified glass fiber, aluminum diethylphosphinate (ADP), melamine cyanurate (MCA), and antioxidant 1098 are weighed according to the following weight parts: 59.5 parts nylon 6, 30 parts flame-retardant modified glass fiber, 8.9 parts aluminum diethylphosphinate, 1.1 parts melamine cyanurate, and 0.5 parts antioxidant 1098. After drying the above raw materials, they are mixed evenly (the flame-retardant modified glass fiber is added from the side feed port), and then melt-extruded and granulated. The resulting granules are dried at 80℃ for 12 hours and then injection molded using an injection molding machine. The temperatures of each section of the extruder are 240, 245, 245, 245, 245, and 245℃, the main screw speed is 90 r / min, and the feeding frequency is 2 Hz; the temperatures of each section of the injection molding machine are 240, 245, 245, and 245℃. A flame-retardant and compatibilized glass fiber reinforced nylon 6 composite material was obtained, denoted as PA6 / GF-HPC / FR.

[0042] Example 2

[0043] A surface-retardant and compatibilized glass fiber reinforced nylon composite material is prepared by the following steps:

[0044] The first step was to synthesize the interfacial compatibilizer HDOPO. The specific preparation steps are as follows: Hydroxyethyl acrylate (6.47 g, 0.55 mol), DOPO (10.00 g, 0.46 mol), triethylamine (5.6 g, 0.55 mol), and dichloromethane (80 mL) were added sequentially to a single-necked flask. The mixture was reacted at 35 °C for 12 h. The reaction solution was extracted three times with water. The organic layer was then rotary evaporated and dried to obtain the product HDOPO. Its 1H NMR spectrum is shown below. Figure 3 As shown.

[0045]

[0046] The second step involves immersing the glass fiber in a mixed solution of KH550, distilled water, and ethanol (20 parts KH550, 8 parts distilled water, and 72 parts ethanol). The pH is adjusted to 4, the temperature is set at 80°C, and the reaction time is 6 hours. Finally, the KH550-treated glass fiber is washed with distilled water and dried for later use.

[0047] The third step involves placing the KH550-treated glass fiber into a large beaker, then adding 0.6 parts of HDOPO and 150 parts of tetrahydrofuran to the beaker, and reacting at 60℃ for 12 hours. Finally, the flame-retardant modified glass fiber is dried and set aside for later use, designated as GF-HDOPO.

[0048] In the fourth step, nylon 6, flame-retardant modified glass fiber, aluminum diethylphosphinate, melamine cyanurate, and antioxidant 1098 are weighed according to their respective weight proportions: 59.5 parts nylon 6, 30 parts flame-retardant modified glass fiber, 8.9 parts aluminum diethylphosphinate, 1.1 parts melamine cyanurate, and 0.5 parts antioxidant 1098. After drying the above raw materials, they are mixed evenly (the flame-retardant modified glass fiber is added from the side feed port), and then melt-extruded and granulated. The resulting granules are dried at 80℃ for 12 hours and then injection molded using an injection molding machine. The temperatures of each section of the extruder are 240, 245, 245, 245, 245, and 245℃, the main screw speed is 90 r / min, and the feeding frequency is 2 Hz; the temperatures of each section of the injection molding machine are 240, 245, 245, and 245℃. A flame-retardant and compatibilized glass fiber reinforced nylon 6 composite material was obtained, denoted as PA6 / GF-HDOPO / FR.

[0049] Example 3

[0050] A surface-retardant and compatibilized glass fiber reinforced nylon composite material is prepared by the following steps:

[0051] The first step is to synthesize the interfacial compatibilizer PPC. The specific preparation steps are as follows: (1) In a round-bottom flask equipped with a constant pressure dropping funnel and a magnetic stirrer, dichloromethane (300 mL), hydroxyethyl acrylate (11.62 g, 0.1 mol), and triethylamine (10.12 g, 0.1 mol) are added in sequence. Under a nitrogen atmosphere, the temperature is kept below 0 °C, and diphenylphosphine chloride (23.66 g, 0.1 mol) is slowly added dropwise. After the addition is complete, the mixture is transferred to room temperature and reacted for 5-6 hours, with the temperature maintained at 25-35 °C. After the reaction is completed, the yellow liquid is repeatedly washed with a large amount of distilled water. After drying, the solvent in the product is removed to obtain intermediate product A.

[0052]

[0053] (2) In a two-necked flask equipped with a condenser, tetrahydrofuran (400 mL), intermediate product A (31.63 g, 0.1 mol), and maleic anhydride (9.80 g, 0.1 mol) were added in sequence. The residual air in the flask was removed, and under nitrogen atmosphere, the catalyst azobisisobutyronitrile (0.12 g) was added. The mixture was refluxed at 90 °C for 24 h to obtain a wine-red liquid. After removing the solvent by rotary evaporation, the wine-red liquid was washed with a large amount of diethyl ether and dried at 70 °C for 12 h to obtain the product PPC. Its 1H NMR spectrum is shown below. Figure 1 As shown.

[0054]

[0055] The second step involves immersing the glass fiber in a mixed solution of KH550, distilled water, and ethanol, with 20 parts KH550, 8 parts distilled water, and 72 parts ethanol. The pH is adjusted to 4-5, the temperature is set at 80℃, and the reaction time is 6 hours. Finally, the KH550-treated glass fiber is washed with distilled water and dried for later use.

[0056] The third step involves placing the KH550-treated glass fiber into a large beaker, then adding 0.6 parts of PPC and 150 parts of tetrahydrofuran to the beaker, and reacting at 60℃ for 12 hours. Finally, the flame-retardant modified glass fiber is dried and set aside for later use, designated as GF-PPC.

[0057] In the fourth step, nylon 6, flame-retardant modified glass fiber, aluminum diethylphosphinate, melamine cyanurate, and antioxidant 1098 are weighed according to their respective weight proportions: 59.5 parts nylon 6, 30 parts flame-retardant modified glass fiber, 8.9 parts aluminum diethylphosphinate, 1.1 parts melamine cyanurate, and 0.5 parts antioxidant 1098. After drying the above raw materials, they are mixed evenly (the flame-retardant modified glass fiber is added from the side feed port), and then melt-extruded and granulated. The resulting granules are dried at 80℃ for 12 hours and then injection molded using an injection molding machine. The temperatures of each section of the extruder are 240, 245, 245, 245, 245, and 245℃, the main screw speed is 90 r / min, and the feeding frequency is 2 Hz; the temperatures of each section of the injection molding machine are 240, 245, 245, and 245℃. A PPC flame-retardant and compatibilized glass fiber reinforced nylon 6 composite material was obtained, denoted as PA6 / GF-PPC / FR.

[0058] Example 4

[0059] A surface-retardant and compatibilized glass fiber reinforced nylon composite material is prepared by the following steps:

[0060] The first step involves immersing glass fibers in a mixed solution of KH570, distilled water, and ethanol (20 parts KH570, 20 parts distilled water, and 80 parts ethanol). The pH is adjusted to 4-5, the temperature is set at 90℃, and the reaction time is 4 hours. Finally, the KH570-treated glass fibers are washed with distilled water and dried for later use.

[0061] The second step involves placing the KH570-treated glass fiber into a large beaker, then adding 1 part HPC and 110 parts acetone to the beaker, and reacting at 80°C for 11 hours. Finally, the flame-retardant modified glass fiber is dried for later use.

[0062] The third step involves weighing nylon 6, flame-retardant modified glass fiber, aluminum diethylphosphinate, melamine polyphosphate, antioxidant 1098, and antioxidant 1076 according to their respective weight proportions. Specifically, nylon 6 comprises 59 parts, flame-retardant modified glass fiber 30 parts, aluminum diethylphosphinate 8.9 parts, melamine polyphosphate 1.1 parts, and antioxidants 1098 and 1076 0.5 parts respectively. After drying the above raw materials, they are mixed evenly (flame-retardant modified glass fiber is added through the side feed port). The mixture is then melt-extruded and granulated. The resulting granules are dried at 80°C for 12 hours and then injection molded using an injection molding machine. The extruder temperatures are 240, 245, 245, 245, 245, and 245°C, the main screw speed is 90 r / min, and the feeding frequency is 2 Hz. The injection molding machine temperatures are also 240, 245, 245, and 245°C. HPC flame-retardant and compatibilized glass fiber reinforced nylon 6 composite material was obtained.

[0063] Example 5

[0064] A surface-retardant and compatibilized glass fiber reinforced nylon composite material is prepared by the following steps:

[0065] The first step involves immersing glass fibers in a mixed solution of KH560, distilled water, and ethanol (20 parts KH560, 10 parts distilled water, and 50 parts ethanol). The pH is adjusted to 4-5, the temperature is 40℃, and the reaction time is 8 hours. Finally, the KH560-treated glass fibers are washed with distilled water and dried for later use.

[0066] The second step involves placing the KH560-treated glass fiber into a large beaker, then adding 0.6 parts HDOPO and 120 parts diethyl ether, and reacting at 50°C for 10 hours. Finally, the flame-retardant modified glass fiber is dried for later use.

[0067] In the third step, nylon 6, flame-retardant modified glass fiber, aluminum diethylphosphinate, melamine polyphosphate, and antioxidant 1010 were weighed according to their respective weight proportions: 59 parts nylon 6, 30 parts flame-retardant modified glass fiber, 8.9 parts aluminum diethylphosphinate, 1.1 parts melamine polyphosphate, and 1 part antioxidant 1010. After drying the above raw materials, they were mixed evenly (the flame-retardant modified glass fiber was added from the side feed port), and then melt-extruded and granulated. The resulting granules were dried at 80℃ for 12 hours and then injection molded using an injection molding machine. The temperatures of each section of the extruder were 240, 245, 245, 245, 245, and 245℃, the main screw speed was 90 r / min, and the feeding frequency was 2 Hz; the temperatures of each section of the injection molding machine were also 240, 245, 245, and 245℃. This yielded the HDOPO flame-retardant and compatibilized glass fiber reinforced nylon 6 composite material.

[0068] Comparative Example 1

[0069] The first step involves immersing glass fibers in a mixed solution of KH550, distilled water, and ethanol (20 parts KH550, 8 parts distilled water, and 72 parts ethanol). The pH is adjusted to 4-5, the temperature is set at 80℃, and the reaction time is 6 hours. Finally, the KH550-treated glass fibers are washed with distilled water and dried for later use.

[0070] In the second step, nylon 6, KH550 modified glass fiber (GF), aluminum diethylphosphinate, melamine cyanurate, HPC, and antioxidant 1098 were weighed according to their respective weight proportions: 59.5 parts nylon 6, 29.4 parts KH550 modified glass fiber, 8.9 parts aluminum diethylphosphinate, 1.1 parts melamine cyanurate, 0.6 parts HPC, and 0.5 parts antioxidant 1098. After drying the above raw materials, they were mixed evenly (glass fiber was added from the side feed port), and then melt-extruded and granulated. The resulting granules were dried at 80℃ for 6 hours and then injection molded using an injection molding machine. The extruder temperatures were 240, 245, 245, 245, 245, and 245℃, the main screw speed was 90 r / min, and the feeding frequency was 2 Hz. The injection molding machine temperatures were also 240, 245, 245, and 245℃. A glass fiber reinforced nylon 6 flame retardant composite material was obtained, denoted as PA6 / GF / FR / HPC.

[0071] Comparative Example 2

[0072] The first step involves immersing glass fibers in a mixed solution of KH550, distilled water, and ethanol (20 parts KH550, 8 parts distilled water, and 72 parts ethanol). The pH is adjusted to 4-5, the temperature is set at 80℃, and the reaction time is 6 hours. Finally, the KH550-treated glass fibers are washed with distilled water and dried for later use.

[0073] In the second step, nylon 6, KH550 modified glass fiber, aluminum diethylphosphinate, melamine cyanurate, HDOPO, and antioxidant 1098 were weighed according to their respective weight proportions: 59.5 parts nylon 6, 29.4 parts KH550 modified glass fiber, 8.9 parts aluminum diethylphosphinate, 1.1 parts melamine cyanurate, 0.6 parts HDOPO, and 0.5 parts antioxidant 1098. After drying the above raw materials, they were mixed evenly (glass fiber was added from the side feed port), and then melt-extruded and granulated. The resulting granules were dried at 80℃ for 6 hours and then injection molded using an injection molding machine. The temperatures of each section of the extruder were 240, 245, 245, 245, 245℃, and 245℃, respectively; the main screw speed was 90 r / min, and the feeding frequency was 2 Hz. The temperatures of each section of the injection molding machine were also 240, 245, 245, and 245℃. A glass fiber reinforced nylon 6 flame retardant composite material was obtained, denoted as PA6 / GF / FR / HDOPO.

[0074] Comparative Example 3

[0075] The first step involves immersing glass fibers in a mixed solution of KH550, distilled water, and ethanol (20 parts KH550, 8 parts distilled water, and 72 parts ethanol). The pH is adjusted to 4-5, the temperature is set at 80℃, and the reaction time is 6 hours. Finally, the KH550-treated glass fibers are washed with distilled water and dried for later use.

[0076] In the second step, nylon 6, KH550 modified glass fiber, aluminum diethylphosphinate, melamine cyanurate, PPC, and antioxidant 1098 were weighed according to their respective weight parts, namely 59.5 parts nylon 6, 29.4 parts KH550 modified glass fiber, 8.9 parts aluminum diethylphosphinate, 1.1 parts melamine cyanurate, 0.6 parts PPC, and 0.5 parts antioxidant 1098. After drying the above raw materials, they were mixed evenly (glass fiber was added from the side feed port), and then melt-extruded and granulated. The resulting granules were dried at 80℃ for 6 hours and then injection molded using an injection molding machine. The temperatures of each section of the extruder were 240, 245, 245, 245, 245℃, and 245℃, respectively; the main screw speed was 90 r / min, and the feeding frequency was 2 Hz. The temperatures of each section of the injection molding machine were also 240, 245, 245, and 245℃. A glass fiber reinforced nylon 6 flame retardant composite material was obtained, denoted as PA6 / GF / FR / PPC.

[0077] Comparative Example 4

[0078] The first step involves immersing glass fibers in a mixed solution of KH570, distilled water, and ethanol (20 parts KH570, 20 parts distilled water, and 80 parts ethanol). The pH is adjusted to 4-5, the temperature is set at 90℃, and the reaction time is 4 hours. Finally, the KH570-treated glass fibers are washed with distilled water and dried for later use.

[0079] In the second step, nylon 6, flame-retardant modified glass fiber, aluminum diethylphosphinate, melamine polyphosphate, HPC, antioxidant 1098, and antioxidant 1076 were weighed according to their respective weight proportions. Specifically, nylon 6 comprised 59 parts, glass fiber 29.4 parts, aluminum diethylphosphinate 8.9 parts, melamine polyphosphate 1.1 parts, HPC 0.6 parts, and antioxidants 1098 and 1076 0.5 parts. After drying the above raw materials, they were mixed evenly (flame-retardant modified glass fiber was added through the side feed port). The mixture was then melt-extruded and granulated. The resulting granules were dried at 80°C for 12 hours and then injection molded using an injection molding machine. The extruder temperatures were 240, 245, 245, 245, 245, and 245°C, the main screw speed was 90 r / min, and the feeding frequency was 2 Hz. The injection molding machine temperatures were also 240, 245, 245, and 245°C. HPC flame-retardant and compatibilized glass fiber reinforced nylon 6 composite material was obtained.

[0080] Comparative Example 5

[0081] The first step involves immersing glass fibers in a mixed solution of KH560, distilled water, and ethanol (20 parts KH560, 10 parts distilled water, and 50 parts ethanol). The pH is adjusted to 4-5, the temperature is 40℃, and the reaction time is 8 hours. Finally, the KH560-treated glass fibers are washed with distilled water and dried for later use.

[0082] In the second step, nylon 6, flame-retardant modified glass fiber, aluminum diethyl phosphinate, melamine polyphosphate, HDPO, and antioxidant 1010 are weighed according to their respective weight proportions: 59 parts nylon 6, 29.4 parts glass fiber, 8.9 parts aluminum diethyl phosphinate, 1.1 parts melamine polyphosphate, 0.6 parts HDPO, and 1 part antioxidant 1010. After drying the above raw materials, they are mixed evenly (the flame-retardant modified glass fiber is added through the side feed port), and then melt-extruded and granulated. The resulting granules are dried at 80℃ for 12 hours and then injection molded using an injection molding machine. The temperatures of each section of the extruder are 240, 245, 245, 245, 245, and 245℃, the main screw speed is 90 r / min, and the feeding frequency is 2 Hz; the temperatures of each section of the injection molding machine are 240, 245, 245, and 245℃. HDOPO flame-retardant and compatibilizing glass fiber reinforced nylon 6 composite material was obtained.

[0083] Comparative Example 6

[0084] The first step involves immersing glass fibers in a mixed solution of KH550, distilled water, and ethanol (20 parts KH550, 8 parts distilled water, and 72 parts ethanol). The pH is adjusted to 4-5, the temperature is set at 80℃, and the reaction time is 6 hours. Finally, the KH550-treated glass fibers are washed with distilled water and dried for later use.

[0085] In the second step, nylon 6, KH550 modified glass fiber, aluminum diethylphosphinate, and antioxidant 1098 were weighed according to their respective weight proportions: 59.5 parts nylon 6, 30 parts KH550 modified glass fiber, 8.9 parts aluminum diethylphosphinate, 1.1 parts melamine cyanurate, and 0.5 parts antioxidant 1098. After drying the above raw materials, they were mixed evenly (glass fiber was added from the side feed port), and then melt-extruded and granulated. The resulting granules were dried at 80℃ for 6 hours and then injection molded using an injection molding machine. The extruder temperatures were 240, 245, 245, 245, 245, and 245℃, the main screw speed was 90 r / min, and the feeding frequency was 2 Hz. The injection molding machine temperatures were also 240, 245, 245, and 245℃. The resulting glass fiber reinforced nylon 6 flame-retardant composite material was denoted as PA6 / GF / FR.

[0086] Comparative Example 7

[0087] The first step involves immersing glass fibers in a mixed solution of KH560, distilled water, and ethanol (20 parts KH560, 10 parts distilled water, and 50 parts ethanol). The pH is adjusted to 4-5, the temperature is 40℃, and the reaction time is 8 hours. Finally, the KH560-treated glass fibers are washed with distilled water and dried for later use.

[0088] In the second step, nylon 6, flame-retardant modified glass fiber, aluminum diethylphosphinate, melamine polyphosphate, and antioxidant 1010 were weighed according to their respective weight proportions: 59 parts nylon 6, 30 parts glass fiber, 8.9 parts aluminum diethylphosphinate, 1.1 parts melamine polyphosphate, and 1 part antioxidant 1010. After drying the above raw materials, they were mixed evenly (the flame-retardant modified glass fiber was added through the side feed port), and then melt-extruded and granulated. The resulting granules were dried at 80℃ for 12 hours and then injection molded using an injection molding machine. The temperatures of each section of the extruder were 240, 245, 245, 245, 245, and 245℃, the main screw speed was 90 r / min, and the feeding frequency was 2 Hz; the temperatures of each section of the injection molding machine were also 240, 245, 245, and 245℃. This yielded a glass fiber reinforced nylon 6 flame-retardant composite material.

[0089] Comparative Example 8

[0090] The first step involves immersing glass fibers in a mixed solution of KH550, distilled water, and ethanol (20 parts KH550, 8 parts distilled water, and 72 parts ethanol). The pH is adjusted to 4-5, the temperature is set at 80℃, and the reaction time is 6 hours. Finally, the KH550-treated glass fibers are washed with distilled water and dried for later use.

[0091] In the second step, nylon 6, KH550 modified glass fiber, and antioxidant 1098 were weighed according to their respective weight proportions, with 69.5 parts of nylon 6, 30 parts of KH550 modified glass fiber, and 0.5 parts of antioxidant 1098. After drying the above raw materials, they were mixed evenly (glass fiber was added from the side feed port), and then melt-extruded and granulated. The resulting granules were dried at 80℃ for 6 hours and then injection molded using an injection molding machine. The temperatures of each section of the extruder were 240, 245, 245, 245, 245℃, and 245℃, respectively; the main screw speed was 90 r / min, and the feeding frequency was 2 Hz. The temperatures of each section of the injection molding machine were also 240, 245, 245, and 245℃. This yielded a glass fiber reinforced nylon 6 composite material.

[0092] Test case

[0093] The amounts of each component in the composite materials prepared in Examples 1-5 and Comparative Examples 1-8 are shown in Table 1, and the corresponding mechanical properties and flame retardant properties are shown in Table 2.

[0094] Table 1. Composition of Glass Fiber Reinforced Nylon 6 Flame Retardant Composite Material

[0095]

[0096]

[0097] Table 2 Performance of Glass Fiber Reinforced Nylon 6 Flame Retardant Composite Materials

[0098]

[0099] As can be seen from the experimental test results of Examples 1-5 and Comparative Examples 1-8 (Table 2), the flame retardant and mechanical properties of the composite materials modified with interface flame retardant compatibilizers in Examples 1-5 are significantly improved compared with those of Comparative Examples 6 and 7 without interface flame retardant compatibilizers. Specifically, the tensile strength, flexural strength, flexural modulus, and notched impact strength of the system using HPC (Example 1) surface-modified glass fiber are increased by 20.7%, 20.0%, 24.1%, and 17.6%, respectively, compared with the system without flame retardant compatibilizers (Comparative Example 6). The samples (Examples 1, 4, and 2) with direct surface modification of fibers using HPC and HDOPO before being compounded with the matrix showed notched impact strength increases of 20.2%, 29.9%, and 21.3%, respectively, compared to samples (Comparative Examples 1, 4, and 2) with HPC and HDOPO directly added to the flame-retardant system. This indicates that direct modification of glass fibers with interfacial flame-retardant compatibilizers can effectively improve the interfacial bonding between the fibers and the matrix resin, solving the problem of deteriorated impact performance of composite materials caused by additive flame retardants. Figure 4 Based on the fiber-matrix interface bonding and pull-out in the impact fracture morphology images of the composite material, the system without added flame retardant compatibilizer (Comparative Example 6) shows... Figure 4 In system a), fiber pull-out is more pronounced, and the pulled-out fiber surface is smoother with less resin residue; while in system with added flame retardant compatibilizer ( Figure 4 The fiber pull-out lengths in Examples 1-3 (bd) were shorter, and there was obvious resin residue on the surface of the pulled-out fibers, indicating that the flame retardant compatibilizers PPC, HPC, and HDOPO had excellent interfacial compatibilizing effects on PA6 / GF / FR. Therefore, the mechanical properties of the corresponding composite systems (Examples 1-5, Comparative Examples 1-5) were better than those of the systems without flame retardant compatibilizers (Comparative Examples 6 and 7). Figure 5 The cross-sectional images of the composite materials with HDOPO surface-modified glass fiber (Example 2) and those with HDOPO directly blended into the system (Comparative Example 2) show that the composite material with direct surface flame retardant and compatibilizing modification of the fiber has a large amount of resin matrix attached to the fiber surface after being damaged by external force. The fiber pull-out degree is shorter than that of the directly blended system (Comparative Example 2). This indicates that the interfacial flame retardant is directly treated on the fiber surface, which can effectively improve the interfacial bonding between the fiber and the matrix. This effect is the key to improving the mechanical properties of glass fiber reinforced nylon 6 flame retardant composite materials.

[0100] Combustion test results showed that all systems with added flame retardant compatibilizers HPC and HDOPO passed the UL-94 rating, achieving a limiting oxygen index (LOI) of over 29%, thus meeting the flame retardancy standard. In particular, the systems with added GF-HPC and GF-HDOPO (Examples 1, 2, 4, and 5) passed the UL-94 V-0 rating. Compared to the system without added flame retardant compatibilizers (Comparative Example 6), the LIO values ​​were increased by over 20.6%, and the ignition time was extended by 14.3%-44.6%, significantly enhancing the flame retardancy of the material.

[0101] At the current addition levels, the flame retardant and mechanical properties of the composite system reinforced with glass fiber directly modified with HPC and HDOPO are superior to those of the composite system directly blended with HPC and HDOPO. Furthermore, the modification effect of the system containing both HPC and HDOPO as interfacial compatibilizers is better than that of the system containing PPC. This is related to the molecular structure of the several interfacial compatibilizers and their dispersion in the matrix. The HPC molecular chain contains multiple anhydride groups, which can undergo grafting reactions with amino groups on the GF surface. The HPC molecular chain contains phosphorus groups, anhydride groups, and carboxyl groups formed after grafting, which can also react with the terminal amino groups on the PA6 chain, thereby promoting the interfacial bonding between GF and the PA6 matrix. PPC has a similar interfacial compatibilization mechanism to HPC. The phosphorus and hydroxyl groups in the HDOPO structure promote the interfacial bonding between the fiber and the matrix by forming hydrogen bonds between GF and PA6. Pre-treating the fiber surface with interfacial compatibilizers allows for the formation of stronger physical and chemical bonds, enabling these compatibilizers to directly act at the fiber-matrix interface during subsequent processing, resulting in a more significant effect. Adding interfacial compatibilizers to the matrix through blending presents challenges such as difficulty migrating to the fiber / matrix interface and uneven distribution, leading to a less effective compatibilization compared to samples where the fiber surface is pre-modified with the compatibilizer. In a fire environment, PPC and HPC can synergistically exert flame-retardant effects through a dual flame-retardant mechanism involving both condensed and gas-phase phases, working in conjunction with FR. At high temperatures, PPC and HPC undergo thermal decomposition, generating PO· free radicals that capture active H·, OH·, and HOO· free radicals in the flame, thereby terminating the chain reaction of the combustion process and acting as a gas-phase flame retardant. HDOPO possesses a similar flame-retardant mechanism to DOPO, releasing PO· free radicals to capture active free radicals in the flame reaction, thus inhibiting the combustion process. The PC bonds in HPC and HDOPO structures are weaker, making them more prone to premature decomposition compared to PPC, forming new phosphates or polyphosphates that coat the surface of combustibles. Simultaneously, the production of polyphosphoric acid, phosphorous acid, and phosphoric acid dehydrates and carbonizes the polyamide matrix, forming a cross-linked, dense char layer. This layer isolates oxygen and heat from the matrix, acting as a condensed-phase flame retardant. When interfacial flame retardant compatibilizers act on the fiber / matrix interface, they directly promote the formation of the char layer at the fiber / matrix interface in a fire environment, reducing the interfacial energy of the glass fiber surface and inhibiting the wetting and diffusion of the polymer melt on the fiber surface. This blocks the "wick effect" caused by the fiber, resulting in superior flame retardant performance.

[0102] In summary, the flame retardant compatibilizer added in the examples significantly solved the flame retardancy problem caused by the "wick effect" of fibers in PA6 / GF. While improving the flame retardant properties of the composite material, it also enhanced its mechanical properties, further meeting the performance requirements of PA6 / GF composite materials in applications such as automotive parts, machinery, and aerospace. Furthermore, modifying the fiber surface with the flame retardant compatibilizer allows for customized fiber production with minimal impact on the processing of the corresponding flame-retardant composite material, which is beneficial for the industrial production and widespread application of fiber-reinforced nylon flame-retardant composite materials.

[0103] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A process for the preparation of a surface flame retardant compatibilized glass fiber reinforced nylon composite material, characterized in that, Flame-retardant compatibilized glass fiber, nylon, flame retardant and antioxidant are mixed according to the mass ratio of (10-30):(40-60):(1-20):(0.1-1), and then extrusion granulation, injection molding to obtain flame-retardant compatibilized glass fiber reinforced nylon composite material; The preparation method of the flame-retardant compatibilized glass fiber comprises the following steps: (1) The glass fiber is soaked in a mixed solution I composed of silane coupling agent and solvent I, the solution PH is adjusted, silane coupling agent modification treatment is carried out, and silane coupling agent modified glass fiber is prepared; (2) The silane coupling agent modified glass fiber is soaked in a mixed solution II composed of interfacial flame-retardant compatibilizer and solvent II, flame-retardant compatibilizer modification treatment is carried out, and flame-retardant compatibilized glass fiber is prepared; The interface flame-retardant compatibilizer is PPC, HPC or HDOPO, the structural formula of PPC is: The structural formula of HPC is: n is an integer; the structural formula of HDOPO is: .

2. The method for preparing the surface flame-retardant and compatibilized glass fiber reinforced nylon composite material according to claim 1, characterized in that, In the step (1), the mass ratio of silane coupling agent to solvent I is 1:(3-5), the silane coupling agent is any one of KH550, KH560, KH570 or KH590; the solvent I is composed of water and ethanol with a mass ratio of (1-2):(8-9); the temperature for silane coupling agent modification treatment is 40-90℃, and the time is 4-8h.

3. The method for preparing the surface flame-retardant and compatibilized glass fiber reinforced nylon composite material according to claim 2, characterized in that, In the step (2), the mixed solution II is prepared by mixing interfacial flame-retardant compatibilizer and solvent II with a mass ratio of 1:(70-110); the solvent II is any one of tetrahydrofuran, diethyl ether, acetone or butanone; the temperature for flame-retardant compatibilizer modification treatment is 50-80℃, and the time is 10-14h.

4. The method for preparing the surface flame-retardant and compatibilized glass fiber reinforced nylon composite material according to claim 1, characterized in that, The flame retardant is one or two or more of aluminum hypophosphite, aluminum diethyl phosphinate, melamine polyphosphate, melamine cyanurate, ammonium polyphosphate, melamine, 9,10-dihydro-9-oxa-10-phospha-phenanthrene-10-oxide and its derivatives, silane structure containing benzoxazine, or phosphorus, nitrogen, sulfur containing halogen-free ionic liquid; the antioxidant is one or two or more of antioxidant 1010, antioxidant 1098, antioxidant 1076.

5. The method for preparing the surface flame-retardant and compatibilized glass fiber reinforced nylon composite material according to claim 1, characterized in that, The process parameters for extrusion granulation are: the extrusion temperature is 240-280℃, the extrusion main screw rotation speed is 90-130rpm, and the feeding frequency is 1-4Hz.

6. The surface flame-retardant compatibilized glass fiber reinforced nylon composite material prepared by the method of any one of claims 2-5.

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