Metal and nylon heterogeneous connecting material with strong interface bonding strength and preparation method thereof

Abstract

The application discloses a metal and nylon heterogeneous connecting material with high interface bonding strength and a preparation method thereof, and comprises the following steps: cleaning a metal sample to remove surface oil stains, and performing chemical etching treatment to obtain a metal with porous and hydroxyl groups on the surface; coating a nylon solution, drying to remove the solvent, and then performing annealing treatment to obtain a metal with a nylon coating on the surface; and performing ultrasonic-assisted injection molding on the metal with injection-molded nylon resin to obtain the heterogeneous connecting material. In the application, a micron-level porous structure is constructed on the surface of the metal by using a chemical etching method, and low-melting-point nylon resin is coated on the surface of the metal. Under the protection of inert gas, high-temperature tempering treatment is performed, so that the nylon resin can better penetrate into the porous structure on the surface of the metal, the metal and the injection-molded nylon resin matrix are better compatible, and thus the interface bonding strength between the metal and the nylon resin matrix composite material is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to a metal and resin or a composite material thereof, and in particular to a metal and nylon heterogeneous connection material with strong interface bonding strength and a preparation method thereof. BACKGROUND

[0002] Metal and thermoplastic resin-based composite hybrid structures have broad prospects in the fields of automobiles, ships, rail transportation, etc. The metal and thermoplastic resin-based composite hybrid structure not only has high strength and high pressure resistance of metal, but also has the advantages of chemical corrosion resistance and fatigue resistance of thermoplastic composite, and greatly reduces the weight of the product. Due to the large difference in physical and chemical properties between the resin-based composite and the metal, efficient and reliable connection between the two is one of the technical problems to be solved.

[0003] Improving the interface bonding strength between metal and resin-based composite is the key to achieving high mechanical properties of metal and resin-based composite hybrid structures. Therefore, when metal and resin-based composite are used together, the surface of the metal must be treated to enhance the physical, mechanical and chemical bonding of the interface between the metal and the resin-based composite. The commonly used metal surface treatment methods are: anodic oxidation treatment, chemical grafting, laser etching, etc.

[0004] The patent application with publication number CN117698038A discloses a metal-plastic composite and a preparation method thereof. The metal surface is roughened by laser and then corroded in an acidic etching solution. The metal-plastic composite is obtained by injection molding technology. Although this method can improve the interface bonding strength between metal and plastic, the melt viscosity of plastic is relatively high, which cannot ensure that the plastic melt can fully infiltrate the metal surface. Therefore, the improvement of the interface bonding strength between metal and plastic is limited.

[0005] The patent application with publication number CN118809931A discloses a metal surface treatment method based on nano-injection molding and application. After electrochemical corrosion treatment of the metal plate to prepare nano-sized holes, terephthalic acid and other raw materials are used to prepare a solution, and the metal plate is immersed in the solution to generate a PBT-like structure, which improves the bonding performance between the metal plate and PBT plastic, enhances the bonding performance between the resin and the metal plate, and increases the bonding strength between the metal and the plastic. Although the solution of terephthalic acid and ethylene glycol can fully infiltrate the metal surface, the molecular weight of the polymer generated by the reaction of terephthalic acid and ethylene glycol at the interface is difficult to control, which will affect the interface bonding strength between PBT resin and metal.

[0006] Therefore, developing a method for improving the interface bonding strength of metal and resin-based composite material is of great significance to expand the application field of resin-based composite material and metal hybrid structure. SUMMARY

[0007] The present application provides a method for improving the interface bonding strength of metal and nylon resin-based composite material heterogeneous connection material, which improves the interface bonding strength of metal and nylon resin-based composite material by chemical etching and coating low-melting-point nylon and ultrasonic-assisted injection molding, and provides technical support for the metal and nylon resin-based composite molding technology field.

[0008] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is:

[0009] A preparation method of metal and nylon heterogeneous connection material with strong interface bonding strength, comprising the steps of:

[0010] Step 1, cleaning the metal sample to remove surface oil stains, and treating the part connected with the injection molded nylon resin by chemical etching to obtain a metal with porous and hydroxyl groups on the surface;

[0011] Step 2, coating a nylon solution on the surface of the metal treated in step 1, drying to remove the solvent, and then annealing to obtain a metal coated with nylon on the surface;

[0012] Step 3, ultrasonic-assisted injection molding of the metal coated with nylon on the surface in step 2 and the injection molded nylon resin to obtain the metal and nylon heterogeneous connection material.

[0013] In the present application, a micron-scale porous structure is constructed on the surface of the metal by chemical etching method, and a low-melting-point nylon resin is coated on the surface of the metal. Under the protection of inert gas, high-temperature tempering treatment is carried out, so that the low-melting-point nylon resin can better penetrate into the porous structure on the surface of the metal. The surface-coated nylon can promote better compatibility of the metal with the nylon matrix or nylon-based composite material, and the bonding force is stronger, thereby preparing a hybrid part of metal and resin-based composite material.

[0014] The method for removing surface oil stains in step 1 includes one or more of inorganic alkali washing, organic solvent washing, water-based cleaning agent cleaning, and water vapor cleaning.

[0015] The inorganic alkali washing specifically includes washing the metal with 0.01-10 mol / L sodium hydroxide for 5-60 min.

[0016] The chemical etching treatment in step 1 includes the steps of:

[0017] Step a, immersing the oil-stain-removed metal connected with the injection molded nylon resin in a hydrochloric acid solution, taking it out, washing and drying;

[0018] Step b, the acid treated metal region is immersed in an ammonia solution, and then taken out, washed and dried.

[0019] Since the aluminum material is easily oxidized in air, the acid treatment is used, on one hand, the acid can react with aluminum oxide to form soluble aluminum salt; on the other hand, the acid can also react with the aluminum metal, so as to achieve the etching effect on the surface of the material; and then the alkali treatment is used, on one hand, the acid can be neutralized, and on the other hand, the aluminum salt can react with the aluminum hydroxide to form aluminum hydroxide, which is an amphoteric hydroxide and can further react with the alkali to form tetrahydroxy aluminate ([Al(OH)4] - After the aluminum material is treated with the acid and the alkali, the surface of the material has a certain amount of hydroxyl, which improves the hydrophilicity of the surface of the material and is beneficial to the impregnation performance of the resin coating.

[0020] The concentration of the hydrochloric acid solution is 0.01-10 mol / L, and the acid treatment time is 1-60 min;

[0021] The concentration of the ammonia solution is 0.5-20 mol / L, and the ammonia treatment time is 1-60 min.

[0022] The melting point of the injection molded nylon resin in step 3 is 20-150℃ different from the melting point of the nylon in the nylon solution in step 2; the purpose of the coated nylon on the metal surface is to improve the compatibility of the metal part and the injection molded nylon; since the coated metal is placed in the mold during the injection molding in step 3, the temperature of the mold is much lower than the melting temperature of the injection molded resin, and after the injection molded resin melt enters the mold, the temperature will decrease, therefore, the melting point of the coated nylon is preferably 20-150℃ lower than the melting point of the nylon used in the injection molding; more preferably, the melting point of the coated nylon is 50-120℃ lower than the melting point of the nylon used in the injection molding, so as to ensure that the temperature of the injection molded nylon entering the mold is sufficient to quickly melt the resin coating on the surface of the metal, so as to achieve the effect of fusion connection.

[0023] The mass concentration of the nylon in the nylon solution is 0.01-20%, and the solvent is one or more of formic acid, trifluoroacetic acid and phenol; more preferably, the mass concentration of the nylon in the nylon solution is 0.1-10%. With the increase of the mass concentration of the nylon in the nylon solution, the interfacial bonding strength of the metal and the resin-based composite material increases, but when the mass concentration of the nylon in the nylon solution reaches a certain value, with the increase of the mass concentration of the nylon in the nylon solution, the interfacial bonding strength decreases. This is because when the solubility of the coated nylon is high, the interfacial layer formed between the composite material and the metal is thick, the molecular chains of the resin matrix in the composite material and the molecular chains of the coated nylon interpenetrate to a limited thickness, which is lower than the thickness of the interfacial coating layer, and since the mechanical strength of the coated nylon resin is lower than that of the injection molded nylon, when a large load is applied, the damage mainly occurs at the interfacial nylon resin, and therefore the interfacial bonding strength decreases. Further preferably, the mass concentration of the nylon is 0.01-5%.

[0024] The nylon used in the nylon solution in step 2 includes one or more of nylon 6, nylon 66, nylon 1010, high-temperature nylon 6T, high-temperature nylon 9T, high-temperature nylon 10T, high-temperature nylon MXD6, and nylon copolymer resin;

[0025] The metal includes one or more of aluminum, aluminum alloy, copper-aluminum alloy, magnesium-aluminum alloy, and magnesium-titanium alloy.

[0026] The injection-molded nylon resin in step 3 includes one or more of nylon 6, nylon 66, nylon 1010, high-temperature nylon 6T, high-temperature nylon 9T, high-temperature nylon 10T, high-temperature nylon MXD6, nylon copolymer resin, or fiber-reinforced resin composite material; and the fiber includes one or more of glass fiber, carbon fiber, ceramic fiber, and aramid fiber.

[0027] The drying temperature in step 2 is 60-120 DEG C, and the drying time is 0.2-2 h.

[0028] The ultrasonic power during the injection molding process is 100-1000 W, and the ultrasonic time is 3-20 s. The ultrasonic during the injection molding process has a very high auxiliary effect on the interface bonding strength, and the ultrasonic time is more dependent on the cooling time of the injection molding, but the ultrasonic power has a greater impact. With the increase of the ultrasonic power, the viscosity of the resin melt is reduced, the impregnation performance and compatibility of the resin to the metal surface are improved, and thus the interface bonding strength of the composite material to the metal is improved. However, too high power will cause imperfect crystallization of the resin, resulting in a decrease in the interface bonding strength. Preferably, the ultrasonic power during the injection molding process is 100-600 W.

[0029] The injection molding process is as follows: the barrel temperature is 250-380 DEG C, the mold temperature is 60-200 DEG C, the holding pressure is 40-160 MPa, and the cooling time is 1-30 s.

[0030] The application also provides a metal and nylon heterogeneous connecting material with strong interface bonding strength prepared by the preparation method.

[0031] Compared with the prior art, the application has the following beneficial effects:

[0032] (1) In the application, the micron-level porous structure is constructed on the surface of the metal, and then a low-melting-point nylon resin is coated, which not only improves the roughness of the metal surface, promotes the mechanical anchoring effect of the metal and the nylon resin matrix, but also enhances the wettability of the metal surface, promotes the better compatibility of the metal and the injection-molded nylon resin matrix, and thus improves the interface bonding strength of the metal and the nylon resin matrix composite material.

[0033] (2) The present application reduces the viscosity of the injection molding grade nylon resin through ultrasonic auxiliary injection molding, improves the fluidity of the matrix, makes the injection molding grade nylon resin further interpenetrate with the low-melting-point nylon molecules, and then penetrates into the holes on the metal surface, so that the mechanical anchoring effect is enhanced, and the interfacial strength between the metal and the nylon resin matrix composite material is further improved. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 The scanning electron microscope image of the cross-sectional morphology of the metal and GF / nylon 66 composite material after chemical etching in Comparative Example 2.

[0035] Figure 2 The scanning electron microscope image of the cross-sectional morphology of the low-melting-point nylon 66 coated and GF / nylon 66 composite material after ultrasonic auxiliary injection molding and chemical etching in Example 2.

[0036] Figure 3 The schematic diagram of the sample with a metal insert in the ultrasonic auxiliary injection molding in the example. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application will be further described in detail below in combination with examples. It should be understood that the specific examples described herein are only used to explain the present application and not to limit the present application. Those skilled in the art can modify or replace equivalently without departing from the spirit and scope of the present application, which should be covered within the protection scope of the present application.

[0038] The raw materials used in the following specific embodiments are all purchased from the market. The aluminum alloy plate used in the examples and comparative examples of the present application is a 6061 type aluminum magnesium silicon type aluminum alloy. The nylon resin matrix composite material used in injection molding is GF / nylon 66 composite material of German BASF, with the model number of A3WG5, the melting point of nylon 66 resin is 260℃; the coated nylon 66 resin is the first model number of A3W, the melting point is 260℃; the second model number is 8061, the melting point is 156℃.

[0039] Interface bonding strength test method (non-standard test method)

[0040] Metal and resin or composite material interface bonding strength test method: on the universal testing machine, the tensile speed is 2mm / min, the test temperature is room temperature 25℃±0.5℃, the measured tensile breaking load T (N), the area of the composite material wrapped metal is S (mm 2 ), the interface bonding strength (F, MPa) of the metal and the composite material is calculated by the formula F=T / S.

[0041] Comparative Example 1

[0042] Step 1, immerse the metal aluminum insert in 1.3 mol / L sodium hydroxide solution, the soaking time is 10 min, remove the surface oil stains, then wash with deionized water to neutral, dry for standby.

[0043] Step 2, put the metal insert into the injection mold, injection The GF / nylon 66 composite material of A3WG5, the mold temperature is 100℃, the barrel temperature is 295℃, the holding pressure is 80 MPa, and the cooling time is 10 s. According to the interface bonding strength test method of metal and resin or composite material, it is tested for interface bonding strength, and the test results are shown in Table 1.

[0044] Comparative Example 2

[0045] Step 1, immerse the metal aluminum insert in 1.3 mol / L sodium hydroxide solution, the soaking time is 10 min, remove the surface oil stains, then wash with deionized water to neutral, dry for standby.

[0046] Step 2, immerse the metal insert with the part connected with the injection nylon composite material in 1.4 mol / L dilute hydrochloric acid solution after removing the surface oil stains, the soaking time is 10 min, so that the micron-sized holes are generated on the surface of the metal, take out, put it into deionized water and wash it to neutral, dry for standby; immerse the metal etched with dilute hydrochloric acid solution in 14.8 mol / L ammonia water, the soaking time is 10 min, take out, wash with deionized water to neutral, dry;

[0047] Step 3, put the metal insert obtained after drying into the injection mold, injection The GF / nylon 66 composite material of A3WG5, the mold temperature is 100℃, the barrel temperature is 295℃, the holding pressure is 80 MPa, and the cooling time is 10 s. According to the interface bonding strength test method of metal and composite material, it is tested for interface bonding strength, and the test results are shown in Table 1. In addition, the cross section of the composite material and the metal aluminum is shown in Figure 1 It can be seen from the figure that there are pores at the interface of the composite material and the metal.

[0048] Example 1

[0049] Step 1, immerse the metal aluminum insert in 1.3 mol / L sodium hydroxide solution, the soaking time is 10 min, remove the surface oil stains, then wash with deionized water to neutral, dry for standby.

[0050] Step 2, immerse the metal insert with the part connected to the injection molded nylon composite in a dilute hydrochloric acid solution with a concentration of 1.4 mol / L for 10 minutes to form micron-sized holes on the metal surface, then take it out and wash it in deionized water until it is neutral, and dry it for use; immerse the metal after etching in the dilute hydrochloric acid solution in ammonia water with a concentration of 14.8 mol / L for 10 minutes, then take it out and wash it in deionized water until it is neutral, and dry it;

[0051] Step 3, select nylon 66 resins with melting points of 156°C and 260°C respectively, dissolve them in formic acid to prepare solutions with concentrations of 0.25%, 0.75%, 1%, and 5% respectively (specific parameters are shown in Table 1), and coat the solutions on the metal surface after chemical etching, place them in a blast oven to remove a large amount of solvent, then place them in a vacuum drying box to remove residual solvent, and then place them in a high-temperature furnace under the protection of inert gas and heat them to 280°C for 10 minutes to complete the metal surface treatment.

[0052] Step 4, place the metal insert with the surface treatment into an injection mold, and inject The GF / nylon 66 composite material of A3WG5 has a mold temperature of 100°C, a barrel temperature of 295°C, a holding pressure of 80 MPa, and a cooling time of 10 s.

[0053] Test the interface bonding strength of the material, and the test results are shown in Table 1.

[0054] Example 2

[0055] Step 1, immerse the metal aluminum insert in a sodium hydroxide solution with a concentration of 1.3 mol / L for 10 minutes to remove the surface oil stains, then wash it in deionized water until it is neutral, and dry it for use.

[0056] Step 2, immerse the metal insert with the part connected to the injection molded nylon composite in a dilute hydrochloric acid solution with a concentration of 1.4 mol / L for 10 minutes to form micron-sized holes on the metal surface, then take it out and wash it in deionized water until it is neutral, and dry it for use; immerse the metal after etching in the dilute hydrochloric acid solution in ammonia water with a concentration of 14.8 mol / L for 10 minutes, then take it out and wash it in deionized water until it is neutral, and dry it;

[0057] Step 3, select a formic acid solution of nylon 66 with a concentration of 0.75% and a melting point of 156°C to coat on the metal surface after chemical etching, place it in a blast oven to remove a large amount of solvent, then place it in a vacuum drying box to remove residual solvent, and then place it in a high-temperature furnace under the protection of inert gas and heat it to 280°C for 10 minutes to complete the metal surface treatment.

[0058] Step 4, put the metal insert with finished surface treatment into the injection mold, inject the resin into the mold, and then take out the metal insert with resin after the resin is cooled and solidified. The GF / nylon 66 composite of A3WG5, the mold temperature is 100℃, the cylinder temperature is 295℃, the packing pressure is 80MPa, the cooling time is 10s, the ultrasonic time is 10s, and the ultrasonic power is 400W.

[0059] Referring to the comparative example 1, the interfacial bonding strength test is carried out, and the test results are shown in Table 1. In addition, the cross section of the composite and the metal aluminum is shown in Figure 2 From the figure, it can be seen that there is almost no pore at the interface of the composite and the metal, and the resin in the composite fills into the metal pores, and the schematic diagram of the sample with metal insert is shown in Figure 3 .

[0060] Example 3

[0061] The difference from example 2 is that the ultrasonic power is 200w when the metal and the resin-based composite are ultrasonic-assisted injection molded, and the rest of the step conditions are the same, and the metal and resin-based composite hybrid parts are prepared. Referring to example 2, the interfacial bonding strength test is carried out, and the results are shown in Table 1.

[0062] Comparative example 3

[0063] The difference from example 2 is that the ultrasonic power is 600w when the metal and the resin-based composite are ultrasonic-assisted injection molded, and the rest of the step conditions are the same, and the metal and resin-based composite hybrid parts are prepared. Referring to example 2, the interfacial bonding strength test is carried out, and the results are shown in Table 1.

[0064] Table 1 interfacial bonding strength of metal and composite

[0065]

[0066] From Table 1, it can be seen that compared with example 1, the ultrasonic-assisted injection during the injection molding process can significantly improve the bonding strength of the resin and the metal. Compared with comparative example 3, too high ultrasonic power is not conducive to the results. This is because the ultrasonic power has a great influence on the viscosity of the resin melt. With the increase of the ultrasonic power, the viscosity of the resin melt decreases, which improves the impregnation performance and compatibility of the resin to the metal surface, thereby improving the interfacial bonding strength of the composite and the metal. However, too high power will cause the breakage of the polymer chain, damage the crystalline structure of the resin, and make the crystallization of the resin imperfect, resulting in a decrease in the interfacial bonding strength.

[0067] The data in Example 1 show that the suitable coating concentration can effectively improve the interfacial bonding strength between the metal and the composite material. This is because the use of low-melting-point nylon 66 resin (Tm = 156°C) for coating the metal surface can effectively improve the wettability of the nylon 66 resin matrix in the GF / nylon 66 composite material to the metal surface. Although the temperature of the mold is relatively low, the temperature of the composite material injected into the mold is higher than 156°C, which can melt the nylon 66 of the coating layer, so that the molecular chains of the resin matrix in the composite material and the molecular chains of the low-melting-point nylon 66 interpenetrate and entangle, thereby improving the interfacial bonding strength between the resin and the metal surface.

[0068] However, when the coating solubility is high, the interfacial layer formed between the composite material and the metal is thick, the interpenetration thickness of the molecular chains of the resin matrix in the composite material and the molecular chains of the low-melting-point nylon 66 is limited, which is lower than the thickness of the interfacial coating layer. In addition, the mechanical strength of the low-melting-point nylon 66 resin is lower than that of the composite material, and when subjected to a large load, the damage mainly occurs at the low-melting-point nylon 66 resin at the interface, so the interfacial bonding strength is reduced. However, when the metal surface is coated with high-melting-point nylon 66 (Tm = 260°C), the temperature of the resin of the composite material injected into the mold will decrease rapidly due to the low temperature of the mold, which is not sufficient to melt the nylon 66 resin on the metal surface, thereby reducing the interfacial bonding strength.

[0069] The above is only a preferred embodiment of the present application, and those skilled in the art can make various modifications or supplements to the described specific embodiments or use similar ways to replace, as long as they do not deviate from the invention or exceed the scope defined by the present claims, which should belong to the protection scope of the present application.

Claims

1. A method for producing a metal and nylon heterogeneous joining material with high interfacial bonding strength, characterized by, The method comprises the steps of: Step 1: cleaning the metal sample to remove surface oil, and performing chemical etching on the part connected with the injection molded nylon resin to obtain a metal with a micrometer porous structure and rich in hydroxyl groups on the surface; The chemical etching treatment comprises: a. first immersing the part of the metal in a hydrochloric acid solution with a concentration of 0.01-10 mol / L for 1-60 min, and then washing and drying the metal after being taken out; b. then immersing the metal after acid treatment in an ammonia water solution with a concentration of 0.5-20 mol / L for 1-60 min, and then washing and drying the metal after being taken out; Step 2: coating a nylon solution on the metal surface after step 1, drying to remove the solvent, and then annealing to obtain a metal coated with nylon; the mass concentration of nylon in the nylon solution is 0.01%-5%, and the melting point of nylon in the nylon solution is 20-150℃ lower than that of the injection molded nylon resin in step 3; Step 3: ultrasonic-assisted injection molding of the metal coated with nylon in step 2 and the injection molded nylon resin to obtain the metal and nylon heterogeneous connection material; the ultrasonic power is 100-600 W.

2. The method of claim 1, wherein the metal and the nylon are different materials. The method for removing surface oil in step 1 comprises one or more of inorganic alkali washing, organic solvent washing, water-based cleaner cleaning, and water vapor cleaning. The inorganic alkali washing specifically comprises: washing the metal with 0.01-10 mol / L sodium hydroxide for 5-60 min.

3. The method of claim 1, wherein the metal and the nylon are different materials. In step 2, the solvent of the nylon solution is one or more of formic acid, trifluoroacetic acid, and phenol.

4. The method of making a metal and nylon dissimilar joint material with high interfacial bond strength according to claim 1, wherein, The nylon used in the nylon solution in step 2 comprises one or more of nylon 6, nylon 66, nylon 1010, high-temperature nylon 6T, high-temperature nylon 9T, high-temperature nylon 10T, high-temperature nylon MXD6, and nylon copolymer resin. The metal comprises one or more of aluminum, aluminum alloy, copper-aluminum alloy, magnesium-aluminum alloy, and magnesium-titanium alloy.

5. The method of making a metal and nylon dissimilar joint material with high interfacial bond strength according to claim 1, wherein, The injection molded nylon resin in step 3 comprises one or more of nylon 6, nylon 66, nylon 1010, high-temperature nylon 6T, high-temperature nylon 9T, high-temperature nylon 10T, high-temperature nylon MXD6, nylon copolymer resin, and fiber-reinforced resin composite material; the fiber comprises one or more of glass fiber, carbon fiber, ceramic fiber, and aramid fiber.

6. The method of making a metal and nylon dissimilar joint material with high interfacial bond strength according to claim 1, wherein, In step 2, the drying temperature is 60-120℃, and the drying time is 0.2-2 h; in step 3, the ultrasonic power during injection molding is 100-1000 W, and the ultrasonic time is 3-20 s.

7. The method of making a metal and nylon dissimilar joint material with high interfacial bond strength according to claim 1, wherein, The injection molding process is as follows: the barrel temperature is 250-380℃, the mold temperature is 60-200℃, the holding pressure is 40-160 MPa, and the cooling time is 1-30 s.

8. The metal and nylon heterogeneous connection material with strong interfacial bonding strength prepared by the method according to any one of claims 1-7.

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