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

Abstract

The application discloses a modified glass fiber reinforced polyamide composite material and a preparation method thereof, wherein raw materials of the composite material by weight percentage comprise the following components: graphene oxide modified glass fiber: 10-40 wt%, polyamide resin: 44-83 wt%, flame retardant: 5-12 wt%, lubricant: 0.2-0.5 wt%, and auxiliary agent: 1-3 wt%. The graphene oxide modified glass fiber and the halogen-free flame retardant are compounded, so that the flame retardant property of the GF / PA material is effectively improved, and meanwhile, the excellent mechanical property is ensured.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of high polymer materials, and particularly relates to a modified glass fiber reinforced polyamide composite material and a preparation method thereof. BACKGROUND

[0002] Glass fiber (GF) reinforced polyamide resin (PA) composite material (GF / PA material) has excellent mechanical strength, good thermal stability and wear resistance, and is widely used in the fields of automobile industry, aerospace, electronic products and sports equipment. With the increasing requirements of terminal application on material safety, the GF / PA material must have good flame retardant performance to reduce the risk of fire. For the GF / PA material, on the one hand, PA as an organic polymer material contains a large amount of carbon and hydrogen elements, which will release flammable gas at high temperature, and is easy to react with oxygen to cause combustion. In addition, PA will also produce a large amount of melt drop during combustion, which will aggravate the fire. On the other hand, although GF is not flammable, the introduction of GF will cause the "candle core effect", which will further aggravate the combustion process. Therefore, developing effective flame retardant technology to improve the flame retardant performance of GF / PA material has been an urgent and important research direction in the industry and academia.

[0003] At present, the flame retardant performance of GF / PA material is generally improved by adding flame retardants in the industry. The commonly used flame retardants achieve the effect of flame retardation through physical effect, such as reducing the temperature of the material combustion surface by dehydration and heat absorption, and hindering the oxygen into the material interior to continue to participate in the combustion reaction. On the other hand, the flame retardants achieve the effect of flame retardation through chemical effect, such as capturing free radicals and promoting carbon formation. However, this traditional flame retardant method cannot solve the "candle core effect" caused by GF, and the increased flame retardant will also seriously affect the mechanical properties of GF / PA material, so it cannot meet the application requirements in the field with higher fireproof requirements.

[0004] In recent years, there has been new progress in the research on solving the "candle core effect" of GF through surface modification technology of GF. In the Chinese patent with the patent number CN202410466322.9, a preparation process of glass fiber composite reinforced modified PET material is disclosed. In the patent, a nitrogen-phosphorus flame-retardant polymer of cyclotriphosphazene and carbazole is grafted to the surface of glass fiber to form a glass fiber composite flame retardant. Since the nitrogen-phosphorus flame-retardant polymer contains more aromatic ring structures, a continuous and dense carbon layer can be formed on the surface of the glass fiber, and a composite carbon-glass fiber barrier layer is formed with the glass fiber, which has the effects of heat insulation, oxygen isolation, and molten droplet prevention, thereby achieving a synergistic flame-retardant effect. However, the flame-retardant method of modifying the glass fiber with the flame retardant reduces the surface energy of the glass fiber, and the reduction of the surface energy leads to poor interfacial compatibility between the glass fiber and the polymer resin, resulting in poor mechanical properties of the composite material, and the flame-retardant performance and the mechanical properties cannot be balanced. SUMMARY

[0005] The present application is to solve the technical problems that the flame retardant cannot effectively solve the "candle core effect" caused by GF in the prior art, resulting in poor flame-retardant performance of GF / PA material, and the addition of the flame retardant leads to a decrease in the mechanical properties of GF / PA material. A modified glass fiber reinforced polyamide composite material and a preparation method thereof are proposed to effectively solve the "candle core effect" caused by GF, thereby improving the flame-retardant performance of GF / PA material, and effectively maintaining the mechanical properties of GF / PA material.

[0006] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0007] A modified glass fiber reinforced polyamide composite material, in terms of weight parts, includes the following components:

[0008] Graphene oxide modified glass fiber: 10-40 parts by weight,

[0009] Polyamide resin: 44-83 parts by weight,

[0010] Flame retardant: 5-12 parts by weight,

[0011] Lubricant: 0.2-0.5 parts by weight,

[0012] Auxiliary agent: 1-3 parts by weight.

[0013] Further, the preparation method of the graphene oxide modified glass fiber includes the following steps:

[0014] S1, the glass fiber is added to the Tris-HCl buffer solution, and dispersed by ultrasonic wave for 15-25 minutes to obtain a mixed dispersion liquid; wherein, the adding ratio of the glass fiber and the Tris-HCl buffer solution is 10 g:1000 mL; the concentration of the Tris-HCl buffer solution is 0.01 mol / L, and pH is 8.5;

[0015] S2, the dopamine hydrochloride is added to the mixed dispersion liquid, and continuously stirred at room temperature for more than 18 hours; when the mixed dispersion liquid changes from yellow brown to black, the reaction is ended and the stirring is stopped; the mixed dispersion liquid is subjected to centrifugal treatment, and the centrifugal product is repeatedly washed with ethanol and deionized water to obtain the polydopamine coated glass fiber; wherein, the adding ratio of the dopamine hydrochloride and the glass fiber is 1 g:10 g;

[0016] S3, the polydopamine coated glass fiber, dopamine hydrochloride, nano titanium dioxide and graphene oxide are sequentially added to the Tris-HCl buffer solution, and continuously stirred at room temperature for more than 18 hours; then, the product is subjected to centrifugal treatment, repeatedly washed with ethanol and deionized water, and vacuum dried at 80℃ until the mass is constant to obtain the graphene oxide modified glass fiber; wherein, the adding amount ratio of the Tris-HCl buffer solution, the polydopamine coated glass fiber, the dopamine hydrochloride, the nano titanium dioxide and the graphene oxide in this step is 1000 mL:10 g:0.5 g:0.5 g:2 g; the concentration of the Tris-HCl buffer solution is 0.01 mol / L, and pH is 8.5.

[0017] Further, the glass fiber is alkali-free chopped glass fiber, the diameter of the glass fiber is ≤15 μm, and the chopped length of the glass fiber is ≤5 mm.

[0018] Further, the polyamide resin is at least one of PA6, PA66, PA56, PA610, PA612, PA11, PA12, PA1010 and PA1012; and the relative viscosity of the polyamide resin is ≥2.0 dl / g.

[0019] Further, the flame retardant is at least one of halogen-free flame retardant, preferably red phosphorus flame retardant (RP), diethyl phosphinic acid aluminum flame retardant (ADP), melamine polyphosphate (MPP) and melamine cyanurate (MCA).

[0020] Further, the lubricant is one of modified ethylene bis fatty acid amide (TAF for short), silicone master batch and montan wax, or a mixture of any two or more thereof in any ratio.

[0021] Further, the silicone master batch is high in content of ultra-high molecular weight siloxane, and the remaining body resin is LDPE or PA6; the montan wax is a mixture of OP wax and E wax; and the mixture of OP wax and E wax is in a ratio of 2:1 in terms of the addition amount of OP wax and E wax.

[0022] Further, the auxiliary agent is at least one of an antioxidant, a light aging auxiliary agent and a colorant.

[0023] The antioxidant is a mixture of a hindered phenol antioxidant and a phosphite antioxidant; the hindered phenol antioxidant is antioxidant 1098; the phosphite antioxidant is antioxidant 168; and the mixture of the hindered phenol antioxidant and the phosphite antioxidant is in a ratio of 1:1 in terms of the addition amount of antioxidant 1098 and antioxidant 168.

[0024] The light aging agent is a mixture of an ultraviolet absorber and a light stabilizer; the ultraviolet absorber is UV-234; the light stabilizer is UV-944; and the mixture of the ultraviolet absorber and the light stabilizer is in a ratio of 1:1 in terms of the addition amount of UV-234 and UV-944.

[0025] A preparation method of the modified glass fiber reinforced polyamide composite material as described above, comprising the following steps:

[0026] After the polyamide resin, the flame retardant, the lubricant and the auxiliary agent are uniformly mixed, they are added into a main feeding port of a double-screw extruder, and the graphene oxide modified glass fiber is added into a side feeding port of the double-screw extruder, so that the composite material is obtained through melt blending, extrusion and granulation of the double-screw extruder.

[0027] The application has the following beneficial effects:

[0028] The graphene oxide modified glass fiber and the halogen-free flame retardant are compounded in the application, which can effectively improve the flame retardant property of the GF / PA material, and meanwhile, the excellent mechanical property is ensured. The active functional groups of the graphene oxide grafted on the surface of the glass fiber can interact with the polyamide resin matrix, so that the interfacial bonding force between the glass fiber and the polyamide resin matrix is enhanced, and the mechanical property of the glass fiber and the polyamide resin compounded matrix is effectively improved. Meanwhile, the graphene oxide with a unique lamellar structure is uniformly dispersed in the polyamide resin, and is stacked layer by layer to form a dense physical barrier layer, so that the flow of the polyamide melt along the glass fiber is blocked, and the "candle core effect" caused by the GF during the combustion of the GF / PA material is eliminated, so that the fire intensification is avoided. In addition, the graphene oxide modified glass fiber also has a certain free radical capturing and carbon forming capacity, and when it is compounded with the halogen-free flame retardant, the synergistic flame retardant effect is achieved, which is beneficial to further improving the flame retardant property of the material.

[0029] The glass fiber is placed in the Tris-HCl buffer solution for uniform dispersion in the preparation of the graphene oxide modified glass fiber, and then hydrochloric acid dopamine is added and stirred for more than 18 hours, so that the dopamine can form a polydopamine layer with strong adsorption capacity on the surface of the glass fiber, thereby effectively ensuring that the graphene oxide can be uniformly adhered to the surface of the glass fiber. The polydopamine interacts with the active functional groups on the surface of the graphene oxide, so that the graphene oxide is reduced and peeled off, and is anchored between the sheet structures, thereby increasing the specific surface area, facilitating the wrapping of the polyamide resin on the graphene oxide sheet, and improving the dispersity of the graphene oxide in the polyamide resin. In addition, the addition amount ratio of the polydopamine coated glass fiber and the graphene oxide is set to 10:2, which can effectively ensure that the surface of the chopped glass fiber can be uniformly coated with the graphene oxide. If the addition amount of the graphene oxide is too low, the graphene oxide cannot form a complete coating on the surface of the glass fiber, and if the addition amount of the graphene oxide is too high, the graphene oxide will be self-aggregated, resulting in uneven coating and clumping on the surface of the glass fiber. At the same time, the nano titanium dioxide particles are deposited on the surface of the graphene oxide, and the presence of the nano particles not only prevents the aggregation of the graphene oxide nanosheets, but also blocks the gap between the glass fiber and the polyamide resin, which is more conducive to the combination of the glass fiber and the polyamide resin.

[0030] The modified glass fiber reinforced polyamide composite prepared by the application can be used in the automobile industry, such as engine covers, vehicle body frames, door interior panels and other key components, and has a broad application prospect. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application will be described clearly and completely below in combination with the technical scheme of the embodiments. Obviously, the described embodiments are only some of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor belong to the scope of protection of the present application. In the description of the present application, the experimental methods, if not specially stated, are conventional methods; the reagents and materials, if not specially stated, can be obtained from commercial channels.

[0032] The following disclosure provides many different embodiments or examples for implementing the present application. In order to simplify the disclosure of the present application, the components and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present application. Those skilled in the art can realize the application of other processes and / or the use of other materials.

[0033] The sources of the main raw materials in the following embodiments and comparative examples of the present application are as follows:

[0034] The fiber material is ECS-10-3.0-T435TM, with a fiber diameter of 10μm and a chopped length of 3.0mm. It was purchased from Taishan Fiberglass Co., Ltd.

[0035] Graphene oxide, with a diameter of 0.5-3 μm, a thickness of 0.55-1.20 nm, and a purity of >99%, was purchased from Beijing Deco Island Gold Technology Co., Ltd.

[0036] Dopamine hydrochloride, CAS Registry No.: 62-31-7, Molecular Formula: C8H11NO2·HCl, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0037] Tris-hydrochloric acid buffer, 1M, pH 8.5, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0038] Nano titanium dioxide, CAS Registry No.: 13463-67-7, particle size 5-20nm, purity >99.8%, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0039] The polyamide 6 (PA6) resin, grade HY-2800, with a relative viscosity of 2.8 dl / g, was purchased from Haiyang Technology Co., Ltd.

[0040] The polyamide 66 (PA66) resin, grade EPR24, with a relative viscosity of 2.4 dl / g, was purchased from Shenma Industrial Co., Ltd.

[0041] The red phosphorus flame retardant, brand name FRP-950-1, contains ≥70% microencapsulated red phosphorus and was purchased from Guangzhou Yinsu Flame Retardant New Materials Co., Ltd.

[0042] The aluminum diethylphosphonate flame retardant, brand name ADP-33, has a phosphorus content of 23.3-24% and was purchased from Qingdao Ouprui New Materials Co., Ltd.

[0043] The silicone masterbatch, brand name GT-500, carrier resin LLDPE, and ultra-high molecular weight siloxane content of 60%, were purchased from Zhejiang Jiahua Fine Chemicals Co., Ltd.

[0044] The OP wax brand is LicowaxOP, purchased from Clariant.

[0045] The wax brand name is LicowaxE, purchased from Clariant.

[0046] The brand name of antioxidant 1098 is Irganox1098, CAS Registry Number: 23128-74-7, purchased from BASF.

[0047] The trade name of antioxidant 168 is Irganox 168, CAS registration number: 31570-04-4, purchased from BASF;

[0048] The trade name of ultraviolet absorber UV-234 is Tinuvn 234, CAS registration number: 70321-86-7, purchased from BASF;

[0049] The trade name of light stabilizer UV-944 is Chimassorb 944, CAS registration number: 71878-19-8, purchased from BASF;

[0050] The remaining reagents are commercially available products.

[0051] The detection methods used in the performance detection of the corresponding products in the embodiments and comparative examples of the present application are as follows:

[0052] The glass fiber reinforced polyamide composite is placed in an injection molding machine to form a standard sample, and then the performance is tested. The injection molding temperature of polyamide 6 (PA6) is 250-275℃, and the injection molding temperature of polyamide 66 (PA66) is 270-300℃.

[0053] The tensile strength is determined according to the ISO 527 method, with a gauge length of 75mm and a test speed of 5mm / min;

[0054] The bending strength is determined according to the ISO 178 method, with a span of 64mm and a test speed of 2mm / min;

[0055] The Charpy notched impact strength is determined according to the ISO 179 method, with a pendulum energy of 4J;

[0056] The vertical burning performance is determined according to the UL94 standard, with a 20mm flame and a sample size of 125mmx12mmx0.8mm.

[0057] Example 1

[0058] A preparation method of a modified glass fiber reinforced polyamide composite material, comprising the following steps:

[0059] 580g of PA6 resin, 70g of red phosphorus flame retardant, 30g of aluminum diethyl phosphinate flame retardant, 2g of lubricant and 18g of auxiliary agent are uniformly mixed and then added to the main feeding port of the twin-screw extruder, and then 300g of graphene oxide modified glass fiber is added to the side feeding port of the twin-screw extruder, and then the twin-screw extruder is used for melt blending, extrusion and granulation to obtain the modified glass fiber reinforced polyamide composite material, which is denoted as S1.

[0060] The preparation method of the graphene oxide modified short glass fiber is as follows:

[0061] S1, 100g glass fibers are added into 10L Tris-HCl buffer solution, and dispersed by ultrasonic wave for 20 minutes to obtain a mixed dispersion liquid; wherein the concentration of the Tris-HCl buffer solution is 0.01mol / L, and pH is 8.5;

[0062] S2, 10g dopamine hydrochloride is added into the mixed dispersion liquid obtained in step S1, and continuously stirred at room temperature for more than 18 hours, and when the mixed dispersion liquid changes from yellow brown to black, the reaction is ended and the stirring is stopped, and the mixed dispersion liquid is subjected to centrifugal treatment, and the centrifugal product is repeatedly washed with ethanol and deionized water to obtain polydopamine coated glass fibers;

[0063] S3, the polydopamine coated glass fibers obtained in step S2, 5g dopamine hydrochloride, 5g nano titanium dioxide and 20g graphene oxide are sequentially added into 10L Tris-HCl buffer solution, and continuously stirred at room temperature for 24 hours, and then subjected to centrifugal treatment, and the centrifugal product is repeatedly washed with ethanol and deionized water, and then vacuum dried at 80℃ until the mass is constant to obtain the graphene oxide modified glass fibers; wherein the concentration of the Tris-HCl buffer solution is 0.01mol / L, and pH is 8.5.

[0064] The lubricant is silicone granules, the auxiliary agent is an antioxidant, the antioxidant is a mixture of a hindered phenolic antioxidant and a phosphite antioxidant; the hindered phenolic antioxidant is antioxidant 1098; the phosphite antioxidant is antioxidant 168; the mass ratio of antioxidant 1098 to antioxidant 168 in the mixture of the hindered phenolic antioxidant and the phosphite antioxidant is 1:1.

[0065] Example 2

[0066] A preparation method of a modified glass fiber reinforced polyamide composite material, comprising the following steps:

[0067] 660g PA6 resin, 90g red phosphorus flame retardant, 30g aluminum diethyl phosphinate flame retardant, 2g lubricant and 18g auxiliary agent are uniformly mixed and then added into the main feeding port of a double screw extruder, and then 200g graphene oxide modified glass fibers are added into the side feeding port of the double screw extruder, and then the double screw extruder is used for melt blending, extrusion and granulation to obtain the modified glass fiber reinforced polyamide composite material, which is denoted as S2.

[0068] In this embodiment, the preparation method of the graphene oxide modified short glass fiber, the type of the lubricant and the type of the auxiliary agent are the same as those in example 1.

[0069] Example 3

[0070] A preparation method of a modified glass fiber reinforced polyamide composite material, comprising the following steps:

[0071] 800g of PA66 resin, 30g of red phosphorus flame retardant, 40g of aluminum diethyl phosphinate flame retardant, 5g of lubricant and 25g of auxiliary agent are uniformly mixed and then added to the main feeding port of the twin-screw extruder, and then 100g of graphene oxide modified glass fiber is added to the side feeding port of the twin-screw extruder, and then the twin-screw extruder is used for melt blending, extrusion and granulation to obtain the modified glass fiber reinforced polyamide composite material, which is denoted as S3.

[0072] In this embodiment, the preparation method of the graphene oxide modified short glass fiber is consistent with that of embodiment 1.

[0073] The lubricant is a mixture of OP wax and E wax with a mass ratio of 2:1;

[0074] The auxiliary agent is a light aging agent, and the light aging agent is a mixture of an ultraviolet light absorber and a light stabilizer; the ultraviolet light absorber is UV-234; the light stabilizer is UV-944; the mass ratio of UV-234 to UV-944 in the mixture of the ultraviolet light absorber and the light stabilizer is 1:1.

[0075] Comparative example 1

[0076] A preparation method of a glass fiber reinforced polyamide composite material, comprising the following steps:

[0077] 580g of PA6 resin, 70g of red phosphorus flame retardant, 30g of aluminum diethyl phosphinate flame retardant, 2g of lubricant and 18g of auxiliary agent are uniformly mixed and then added to the main feeding port of the twin-screw extruder, and then 300g of short glass fiber is added to the side feeding port of the twin-screw extruder, and then the twin-screw extruder is used for melt blending, extrusion and granulation to obtain the glass fiber reinforced polyamide composite material, which is denoted as D1.

[0078] The lubricant is a silicone master batch, the auxiliary agent is an antioxidant, and the antioxidant is a mixture of a hindered phenolic antioxidant and a phosphite antioxidant; the hindered phenolic antioxidant is antioxidant 1098; the phosphite antioxidant is antioxidant 168; the mass ratio of antioxidant 1098 to antioxidant 168 in the mixture of the hindered phenolic antioxidant and the phosphite antioxidant is 1:1.

[0079] The difference between the present comparative example and the above-mentioned embodiment 1 is that the graphene oxide modified short glass fiber is replaced by unmodified short glass fiber.

[0080] Comparative example 2

[0081] A preparation method of a modified glass fiber reinforced polyamide composite material, comprising the following steps:

[0082] After 580g PA6 resin, 70g red phosphorus flame retardant, 30g aluminum diethyl phosphinate flame retardant, 2g lubricant and 18g auxiliary agent are uniformly mixed, they are added to the main feeding port of the double screw extruder, then 300g graphene oxide modified glass fiber is added to the side feeding port of the double screw extruder, and the double screw extruder is used for melt blending, extrusion and granulation, so that the modified glass fiber reinforced polyamide composite material is obtained, which is denoted as D2.

[0083] The preparation method of the graphene oxide modified short glass fiber is as follows:

[0084] S1, 100g glass fiber is added to 10L Tris-HCl buffer solution, and dispersed by ultrasonic wave for 20 minutes to obtain a mixed dispersion liquid; wherein the concentration of the Tris-HCl buffer solution is 0.01mol / L, and pH is 8.5;

[0085] S2, 10g dopamine hydrochloride is added to the mixed dispersion liquid obtained in step S1, and continuously stirred at room temperature for more than 18 hours, and when the mixed dispersion liquid changes from yellow brown to black, the reaction is ended and the stirring is stopped, and the mixed dispersion liquid is subjected to centrifugal treatment, and the centrifugal product is repeatedly washed with ethanol and deionized water to obtain polydopamine coated glass fiber;

[0086] S3, the polydopamine coated glass fiber obtained in step S2, 5g dopamine hydrochloride, 5g nano titanium dioxide and 10g graphene oxide are sequentially added to 10L Tris-HCl buffer solution, and continuously stirred at room temperature for 24 hours, and then subjected to centrifugal treatment, and the centrifugal product is repeatedly washed with ethanol and deionized water, and then vacuum dried at 80℃ until the mass is constant, so that the graphene oxide modified glass fiber is obtained; wherein the concentration of the Tris-HCl buffer solution is 0.01mol / L, and pH is 8.5.

[0087] The lubricant is silicone granules, the auxiliary agent is an antioxidant, the antioxidant is a mixture of a hindered phenolic antioxidant and a phosphite antioxidant; the hindered phenolic antioxidant is antioxidant 1098; the phosphite antioxidant is antioxidant 168; and the mass ratio of antioxidant 1098 to antioxidant 168 in the mixture of the hindered phenolic antioxidant and the phosphite antioxidant is 1:1.

[0088] The difference between the present comparative example and the above-mentioned example 1 is that the amount of graphene oxide is reduced from 20g to 10g when preparing the graphene oxide modified short glass fiber.

[0089] Comparative example 3

[0090] A preparation method of a modified glass fiber reinforced polyamide composite material, comprising the following steps:

[0091] After 580g PA6 resin, 70g red phosphorus flame retardant, 30g aluminum diethyl phosphinate flame retardant, 2g lubricant and 18g auxiliary agent are uniformly mixed, they are added to the main feeding port of the double screw extruder, then 300g graphene oxide modified glass fiber is added to the side feeding port of the double screw extruder, and the double screw extruder is used for melt blending, extrusion and granulation to obtain the modified glass fiber reinforced polyamide composite material, which is denoted as D3.

[0092] The preparation method of the graphene oxide modified short glass fiber is as follows:

[0093] S1, 100g glass fiber is added to 10L Tris-HCl buffer solution and dispersed by ultrasonic wave for 20 minutes to obtain a mixed dispersion liquid; wherein the concentration of the Tris-HCl buffer solution is 0.01mol / L, and pH is 8.5;

[0094] S2, 10g dopamine hydrochloride is added to the mixed dispersion liquid obtained in step S1 and continuously stirred at room temperature for more than 18 hours, and the reaction is stopped when the mixed dispersion liquid changes from yellow brown to black, and the mixed dispersion liquid is centrifuged, and the centrifuged product is repeatedly washed with ethanol and deionized water to obtain polydopamine coated glass fiber;

[0095] S3, the polydopamine coated glass fiber obtained in step S2, 5g dopamine hydrochloride, 5g nano titanium dioxide and 30g graphene oxide are sequentially added to 10L Tris-HCl buffer solution, and continuously stirred at room temperature for 24 hours, and then centrifuged, and the centrifuged product is repeatedly washed with ethanol and deionized water, and then vacuum dried at 80℃ until the mass is constant, to obtain the graphene oxide modified glass fiber; wherein the concentration of the Tris-HCl buffer solution is 0.01mol / L, and pH is 8.5.

[0096] The lubricant is silicone granules, the auxiliary agent is an antioxidant, the antioxidant is a mixture of a hindered phenolic antioxidant and a phosphite antioxidant; the hindered phenolic antioxidant is antioxidant 1098; the phosphite antioxidant is antioxidant 168; the mass ratio of antioxidant 1098 to antioxidant 168 in the mixture of the hindered phenolic antioxidant and the phosphite antioxidant is 1:1.

[0097] The difference between the present comparative example and the above-mentioned example 1 is that the amount of graphene oxide is increased from 20g to 30g when preparing the graphene oxide modified short glass fiber.

[0098] Comparative example 4

[0099] A preparation method of a modified glass fiber reinforced polyamide composite material, comprising the following steps:

[0100] After 580g PA6 resin, 70g red phosphorus flame retardant, 30g aluminum diethyl phosphinate flame retardant, 2g lubricant and 18g auxiliary agent are uniformly mixed, they are added to the main feeding port of the double screw extruder, then 300g graphene oxide modified glass fiber is added to the side feeding port of the double screw extruder, and the double screw extruder is used for melt blending, extrusion and granulation, so that the modified glass fiber reinforced polyamide composite material is obtained, which is denoted as D4.

[0101] The preparation method of the graphene oxide modified short glass fiber is as follows:

[0102] S1, 100g glass fiber is added to 10L Tris-HCl buffer solution, and dispersed by ultrasonic wave for 20 minutes to obtain a mixed dispersion liquid; wherein the concentration of the Tris-HCl buffer solution is 0.01mol / L, and pH is 8.5;

[0103] S2, 10g dopamine hydrochloride is added to the mixed dispersion liquid obtained in step S1, and continuously stirred at room temperature for more than 18 hours, and when the mixed dispersion liquid changes from yellow brown to black, the reaction is stopped and the stirring is stopped, and the mixed dispersion liquid is centrifuged, and the centrifuged product is repeatedly washed with ethanol and deionized water to obtain polydopamine coated glass fiber;

[0104] S3, the polydopamine coated glass fiber obtained in step S2, 10g dopamine hydrochloride and 20g graphene oxide are sequentially added to 10L Tris-HCl buffer solution, and continuously stirred at room temperature for 24 hours, and then centrifuged, and the centrifuged product is repeatedly washed with ethanol and deionized water, and then vacuum dried at 80℃ until the mass is constant, so that the graphene oxide modified glass fiber is obtained; wherein the concentration of the Tris-HCl buffer solution is 0.01mol / L, and pH is 8.5.

[0105] The lubricant is silicone master granules, the auxiliary agent is an antioxidant, the antioxidant is a mixture of hindered phenolic antioxidant and phosphite antioxidant; the hindered phenolic antioxidant is antioxidant 1098; the phosphite antioxidant is antioxidant 168; the mass ratio of antioxidant 1098 to antioxidant 168 in the mixture of hindered phenolic antioxidant and phosphite antioxidant is 1:1.

[0106] The difference between the present comparative example and the above-mentioned example 1 is that the nano titanium dioxide is replaced by dopamine hydrochloride when preparing the graphene oxide modified short glass fiber.

[0107] Comparative example 5

[0108] A preparation method of a modified glass fiber reinforced polyamide composite material, comprising the following steps:

[0109] After 580g of PA6 resin, 70g of red phosphorus flame retardant, 30g of aluminum diethyl phosphinate flame retardant, 2g of lubricant and 18g of auxiliary agent are uniformly mixed, they are added to the main feeding port of the twin-screw extruder, and then 300g of graphene oxide modified glass fiber is added to the side feeding port of the twin-screw extruder. The modified glass fiber reinforced polyamide composite material is obtained by melt blending, extruding and granulating in the twin-screw extruder, which is denoted as D5.

[0110] The preparation method of the graphene oxide modified short glass fiber is as follows:

[0111] In a 10L Tris-HCl buffer solution, 100g of glass fiber, 5g of dopamine hydrochloride, 5g of nano titanium dioxide and 20g of graphene oxide are sequentially added, and continuously stirred at room temperature for 24 hours. After centrifugal treatment, the centrifugal product is repeatedly washed with ethanol and deionized water, and vacuum dried at 80℃ until the mass is constant. The graphene oxide modified glass fiber is obtained. The concentration of the Tris-HCl buffer solution is 0.01mol / L, and the pH is 8.5.

[0112] The lubricant is a silicone master batch, the auxiliary agent is an antioxidant, the antioxidant is a mixture of a hindered phenolic antioxidant and a phosphite antioxidant, the hindered phenolic antioxidant is antioxidant 1098, the phosphite antioxidant is antioxidant 168, and the mass ratio of antioxidant 1098 to antioxidant 168 in the mixture of the hindered phenolic antioxidant and the phosphite antioxidant is 1:1.

[0113] The difference between the present comparative example and the above-mentioned example 1 is that dopamine hydrochloride is not used for pretreatment of glass fiber when preparing graphene oxide modified short glass fiber.

[0114] Performance detection test

[0115] In order to better verify the mechanical properties and flame retardant properties of the composite materials obtained in the above examples and comparative examples, the tensile strength, bending strength, notched impact strength and vertical burning performance (i.e. flame retardant performance) of the composite materials obtained in examples 1-3 and comparative examples 1-5 are detected, and the detection results are as follows:

[0116]

[0117] As can be seen from the test data of the above Examples 1-3, the GF / PA composite prepared by the method of the present application not only maintains good mechanical properties, but also has excellent fireproof performance. Specifically, by adding the graphene oxide modified glass fiber and the halogen-free flame retardant to the polyamide resin, the active functional groups of the graphene oxide grafted on the surface of the glass fiber can interact with the polyamide resin matrix, thereby enhancing the interfacial bonding force between the glass fiber and the polyamide resin matrix, and effectively improving the mechanical properties of the glass fiber and the polyamide resin composite matrix. At the same time, the unique layered structure of the graphene oxide uniformly dispersed in the polyamide resin forms a dense physical barrier layer, which blocks the flow of the polyamide melt along the glass fiber, thereby eliminating the "candle core effect" caused by GF when the GF / PA material burns, thereby avoiding the situation of intensifying the fire. Therefore, the UL94 fireproof grade of the composite material can reach V-0 level.

[0118] As can be seen from the test data of Example 1 and Comparative Example 1, the glass fiber is not modified, and the "candle core effect" caused by GF when the GF / PA composite burns is obvious, thereby resulting in poor flame retardancy, only V-2 level. At the same time, the tensile strength, bending strength and notched impact strength are respectively 12.0%, 7.9% and 17.2% lower than those of Example 1.

[0119] As can be seen from the test data of Example 1 and Comparative Example 2, when the glass fiber is modified, the addition amount of graphene oxide cannot be too low. When the addition amount of graphene oxide is too low, a complete coating layer cannot be formed on the surface of the glass fiber, and due to the uneven coating layer, the dispersion of graphene oxide in the polyamide resin is affected, resulting in poor flame retardancy, and therefore the UL94 fireproof grade of Comparative Example 2 is only V-1 level. However, due to the active functional groups on the surface of the graphene oxide, which can interact with the polyamide resin matrix, the interfacial bonding force between the glass fiber and the polyamide resin matrix is enhanced, and therefore the mechanical properties are higher than those of Comparative Example 1.

[0120] As can be seen from the test data of Example 1 and Comparative Example 3, when the glass fiber is modified, the addition amount of graphene oxide cannot be too high. When the addition amount of graphene oxide is too high, self-aggregation phenomenon occurs, resulting in uneven coating layer and clumping on the surface of the glass fiber. When the self-aggregation phenomenon of graphene oxide is serious, it will eventually affect the flame retardant performance of the GF / PA composite, and the UL94 fireproof grade of the GF / PA composite obtained in Comparative Example 3 is only V-2 level, which is worse than that of Comparative Example 2. However, due to the active functional groups on the surface of the graphene oxide, which can interact with the polyamide resin matrix, the interfacial bonding force between the glass fiber and the polyamide resin matrix is enhanced, and therefore the mechanical properties are higher than those of Comparative Example 1.

[0121] From the test data of Example 1 and Comparative Example 4, it can be seen that when the glass fiber is modified without adding nano-titanium dioxide, the flame retardant performance of the GF / PA composite material is seriously affected, and the UL94 fireproof grade is only V-1. The possible reason is that nano-titanium dioxide is deposited on the surface of graphene oxide during preparation, thereby preventing the aggregation of graphene oxide nanosheets and avoiding the occurrence of graphene oxide self-aggregation phenomenon, so that the graphene oxide can be well dispersed in the polyamide resin, thereby effectively eliminating the "candle core effect" caused by GF during the combustion of GF / PA material. In addition, without adding nano-titanium dioxide, the gap between the glass fiber and the polyamide resin cannot be well blocked, resulting in weak combination of the glass fiber and the polyamide resin, so the mechanical properties are not as good as Example 1.

[0122] From the test data of Example 1 and Comparative Example 5, it can be seen that the graphene oxide is not treated with dopamine hydrochloride, so that the graphene oxide cannot be well adsorbed on the glass fiber, resulting in poor flame retardant performance and mechanical properties, which are similar to the performance of unmodified glass fiber. Dopamine can form polydopamine in aqueous solution, and this polydopamine has excellent adhesion properties and can be firmly adsorbed on the surface of a solid, and is widely used in multifunctional surface coatings in different fields.

[0123] In the above examples, the description of each example has its own focus, and the parts not described in detail in a certain example can be referred to the related description of other examples.

[0124] The above describes in detail the preparation method of the modified glass fiber reinforced polyamide composite material provided by the embodiments of the present application. In this paper, specific examples are applied to explain the principles and implementation modes of the present application. The above example is only used to help understand the technical solutions and core ideas of the present application; those skilled in the art should understand that they can still modify the technical solutions recorded in the above examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A modified glass fiber reinforced polyamide composite, characterized in that: The raw materials include the following components in parts by weight: Oxidized graphene modified glass fiber: 10-40 parts by weight, Polyamide resin: 44-83 parts by weight, Flame retardant: 5-12 parts by weight, Lubricant: 0.2-0.5 parts by weight, Auxiliary agent: 1-3 parts by weight; The auxiliary agent is at least one of an antioxidant, a light aging auxiliary agent, and a colorant; The preparation method of the oxidized graphene modified glass fiber includes the following steps: S1, glass fiber is added to Tris-HCl buffer solution and dispersed by ultrasonic wave for 15-25 minutes to obtain a mixed dispersion liquid; wherein the adding ratio of the glass fiber and the Tris-HCl buffer solution is 10g:1000mL; the concentration of the Tris-HCl buffer solution is 0.01mol / L, and pH=8.5; S2, dopamine hydrochloride is added to the mixed dispersion liquid and continuously stirred at room temperature for more than 18 hours; when the mixed dispersion liquid changes from yellow brown to black, the reaction is ended and the stirring is stopped; the mixed dispersion liquid is subjected to centrifugal treatment, and the centrifugal product is repeatedly washed with ethanol and deionized water to obtain polydopamine coated glass fiber; wherein the adding ratio of the dopamine hydrochloride and the glass fiber is 1g:10g; S3, polydopamine coated glass fiber, dopamine hydrochloride, nano titanium dioxide, and oxidized graphene are sequentially added to Tris-HCl buffer solution and continuously stirred at room temperature for more than 18 hours; then the product is subjected to centrifugal treatment, repeatedly washed with ethanol and deionized water, and vacuum dried at 80℃ until the mass is constant to obtain the oxidized graphene modified glass fiber; wherein the adding amount ratio of the Tris-HCl buffer solution, the polydopamine coated glass fiber, the dopamine hydrochloride, the nano titanium dioxide, and the oxidized graphene in this step is 1000mL:10g:0.5g:0.5g:2g; the concentration of the Tris-HCl buffer solution is 0.01mol / L, and pH=8.

5.

2. A modified glass fiber reinforced polyamide composite according to claim 1, characterized in that, The glass fiber is alkali-free chopped glass fiber, the diameter of the glass fiber is ≤15μm, and the chopped length of the glass fiber is ≤5mm.

3. A modified glass fiber reinforced polyamide composite according to claim 1, characterized in that, The polyamide resin is at least one of PA6, PA66, PA56, PA610, PA612, PA11, PA12, PA1010, and PA1012; and the relative viscosity of the polyamide resin is ≥2.0dl / g.

4. The modified glass fiber reinforced polyamide composite according to claim 1, characterized in that, The flame retardant is a halogen-free flame retardant.

5. The modified glass fiber reinforced polyamide composite according to claim 1, characterized in that, The flame retardant is at least one of red phosphorus flame retardant, aluminum diethyl phosphinate flame retardant, melamine polyphosphate, and melamine cyanurate.

6. A modified glass fiber reinforced polyamide composite according to claim 1, characterized in that, The lubricant is one of modified ethylene bis fatty acid amide, silicone master batch, and montan wax, or a mixture of any two or more thereof in any ratio.

7. A modified glass fiber reinforced polyamide composite according to claim 6, characterized in that, The content of ultra-high molecular weight siloxane in the silicone master batch is higher than 50%, and the remaining carrier resin is LDPE or PA6; the montan wax is a mixture of OP wax and E wax; and the adding amount ratio of OP wax to E wax in the mixture of OP wax and E wax is 2:

1.

8. A process for the production of a modified glass fiber reinforced polyamide composite according to any one of claims 1 to 7, characterized in that, The method includes the following steps: The polyamide resin, the flame retardant, the lubricant and the auxiliary agent are mixed uniformly, then are added into a main feeding port of a double screw extruder, the graphene oxide modified glass fiber is added into a side feeding port of the double screw extruder according to the proportion by weight, and the composite material is obtained through melt blending, extrusion and granulation of the double screw extruder.

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