A preparation method for improving the interface performance of polytrifluorochloroethylene and metal matrix thermoplastic compression molding

Abstract

The application provides a preparation method for improving the interface performance of polytrifluorochloroethylene and a metal matrix in hot plastic die forming. The method comprises the following steps: S1, modifying the surface of polytrifluorochloroethylene powder through a dopamine solution; and S2, integrally forming the modified polytrifluorochloroethylene with a metal matrix in a mold through hot pressing. The method for modifying the surface of polytrifluorochloroethylene through a dopamine solution can effectively enhance the bonding strength of polytrifluorochloroethylene and a metal, and has important applications in polytrifluorochloroethylene valve and valve aerospace products.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of polymer-metal matrix composites, and particularly relates to a preparation method for improving the interface performance of polytrifluorochloroethylene and a metal matrix in hot plastic die forming. BACKGROUND

[0002] Polytrifluorochloroethylene (PCTFE) is an important member of the fluoroplastic family. The structure containing F atoms and CI atoms makes PCTFE have good heat resistance, non-flammability and very excellent low-temperature performance, and can be used for a long time at a low temperature of-200 DEG C, does not crack and does not creep in a liquid nitrogen and liquid oxygen environment, and maintains certain flexibility and impact strength, and has important applications in the fields of electronic appliances, aerospace and the like.

[0003] At present, the valve rod product material of a liquid hydrogen and liquid oxygen filling valve of a carrier rocket in China is metal. When the filling valve moves, the metals are prone to wear, thereby causing movement stagnation. The movement flexibility of a new generation of carrier rocket filling valves is one of the keys to reliable work of the valve. Therefore, polytrifluorochloroethylene is selected to coat the valve rod when the valve product is designed, so as to improve the reliability of the valve. A traditional process adopts a cold sticking method to coat a layer of polytrifluorochloroethylene on the valve rod. However, due to the inertness of polytrifluorochloroethylene, the bonding performance between polytrifluorochloroethylene and the metal valve is poor, gas leakage is easy to occur, and the phenomenon of debonding occurs in the later use.

[0004] Patent CN106563629A discloses a polytrifluorochloroethylene and metal matrix hot plastic pressing pretreatment primer and a preparation method. The method first configures a dispersion liquid containing polytrifluorochloroethylene, uniformly applies the dispersion liquid to the surface of a sandblasted metal matrix, and then prepares a valve piece connected with the polytrifluorochloroethylene and the metal matrix through a hot plastic die forming method after the dispersion liquid is completely dried. The method effectively penetrates the dispersion liquid to the concave-convex parts of the sandblasted metal through the application method, generates a mechanical engagement force at the interface, and thereby improves the interface performance. However, the mechanical engagement force is weaker than a chemical bond, and there are still certain defects at the interface, which cannot guarantee the stability of the product. SUMMARY

[0005] In view of the deficiencies in the prior art, the application provides a preparation method for improving the interface performance of polytrifluorochloroethylene and a metal matrix in hot plastic die forming. In the application, polydopamine is used to modify polytrifluorochloroethylene powder, and then the modified polytrifluorochloroethylene is integrally formed with the metal matrix through hot plastic pressing. The polydopamine nanolayer improves the interface performance between the polytrifluorochloroethylene and the metal matrix.

[0006] The purpose of the application is achieved by the following technical scheme:

[0007] The application discloses a preparation method for improving the interface performance of polytrifluorochloroethylene and a metal matrix in hot plastic die forming, and comprises the following steps:

[0008] S1, modifying the surface of polytrifluorochloroethylene powder by a dopamine solution, and obtaining the polytrifluorochloroethylene modified by polydopamine by filtering or centrifuging after the reaction is completed;

[0009] S2, integrally forming the modified polytrifluorochloroethylene and a metal matrix in a mold by hot pressing.

[0010] Preferably, in step S1, the size of the polytrifluorochloroethylene powder is about 20-1000 mesh.

[0011] Preferably, in step S1, the concentration of the dopamine solution is 1-4 mg / mL.

[0012] Preferably, in step S1, the pH value of the dopamine solution is 7.5-9.5, and the pH regulator is tris or ammonia.

[0013] Preferably, in step S1, the polytrifluorochloroethylene powder is treated by the dopamine solution for 2-48 h, and the stirring speed is 100-500 rpm.

[0014] Preferably, in step S1, the thickness of the polydopamine modified layer obtained after the polytrifluorochloroethylene powder is treated by the dopamine solution is 20-200 nm.

[0015] Preferably, in step S2, the metal part can be stainless steel, aluminum or GH4169 high-temperature alloy.

[0016] Preferably, in step S2, the die forming temperature of the polytrichloroethylene is 230-250 DEG C, the die forming pressure is 1-4 MPa, and the die forming time is 15-90 min.

[0017] Compared with the prior art, the application has the beneficial effects as follows:

[0018] The polytrifluorochloroethylene is modified by polydopamine, and is integrally formed with a metal matrix after hot plastic die pressing. Compared with pre-coating a layer of primer on the surface of the metal, on the one hand, considering the irregular structure of the surface, the primer has non-uniformity in coating, and the primer still improves the interface performance by mechanical engagement, while the presence of polydopamine in the application can increase the interface performance between the polytrifluorochloroethylene and the metal matrix by the action of chemical bonds, and the chemical bonds are more firm than the mechanical engagement force. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is a schematic diagram of the steps of the preparation method. DETAILED DESCRIPTION

[0020] The application will be described in detail below with reference to specific embodiments. The following examples will help those skilled in the art to further understand the application, but do not limit the application in any form. It should be pointed out that those skilled in the art can make several modifications and improvements without departing from the concept of the application. These all belong to the protection scope of the application.

[0021] In order to further illustrate the technical effects of the application, the inventors have carried out related experiments. Table 1 is the tear strength of polytrifluorochloroethylene before and after modification after hot pressing, cold pressing and metal substrate.

[0022] Example 1

[0023] This embodiment relates to polydopamine modified polytrifluorochloroethylene, and the specific preparation includes the following steps: dispersing 5g of polytrifluorochloroethylene in 100mL of dopamine solution (2mg / mL), adjusting the solution pH to 8.5 by tris-hydroxymethyl aminomethane, uniformly and gently stirring for 12h, and obtaining polydopamine modified polytrifluorochloroethylene through filtration and drying.

[0024] Example 2

[0025] This embodiment relates to polydopamine modified polytrifluorochloroethylene, and the specific preparation includes the following steps: dispersing 5g of polytrifluorochloroethylene in 100mL of dopamine solution (2mg / mL), adjusting the solution pH to 8.5 by tris-hydroxymethyl aminomethane, uniformly and gently stirring for 24h, and obtaining polydopamine modified polytrifluorochloroethylene through filtration and drying.

[0026] Example 3

[0027] This embodiment relates to polydopamine modified polytrifluorochloroethylene, and the specific preparation includes the following steps: dispersing 5g of polytrifluorochloroethylene in 100mL of dopamine solution (2mg / mL), adjusting the solution pH to 8.5 by tris-hydroxymethyl aminomethane, uniformly and gently stirring for 48h, and obtaining polydopamine modified polytrifluorochloroethylene through filtration and drying.

[0028] Example 4

[0029] This embodiment relates to polydopamine modified polytrifluorochloroethylene and metal substrate hot plastic pressing integrated molding, and the specific preparation includes the following steps: adding 3g of polydopamine modified polytrifluorochloroethylene (Example 2) to a hot pressing mold, the mold temperature is 230℃, the holding pressure is 2MPa, and the mold pressing time is 60min.

[0030] Example 5

[0031] This example relates to the thermoplastic compression molding of polydopamine modified polytrifluorochloroethylene and metal substrate, and the specific preparation includes the following steps: 3g of polydopamine modified polytrifluorochloroethylene (Example 2) is added to a hot-pressing mold, the mold temperature is 240°C, the holding pressure is 2MPa, and the mold pressing time is 60min.

[0032] Example 6

[0033] This example relates to the thermoplastic compression molding of polydopamine modified polytrifluorochloroethylene and metal substrate, and the specific preparation includes the following steps: 3g of polydopamine modified polytrifluorochloroethylene (Example 2) is added to a hot-pressing mold, the mold temperature is 250°C, the holding pressure is 2MPa, and the mold pressing time is 60min.

[0034] Comparative Example 1

[0035] This example relates to the thermoplastic compression molding of polytrifluorochloroethylene and metal substrate, and the specific preparation includes the following steps: 3g of polytrifluorochloroethylene is added to a hot-pressing mold, the mold temperature is 240°C, the holding pressure is 2MPa, and the mold pressing time is 60min.

[0036] Table 1 Tearing strength of polytrifluorochloroethylene before and after modification and metal substrate

[0037] Sample Tear strength (MPa) Example 4 32.9 Example 5 36.5 Example 6 30.7 Comparative Example 1 Comparative Example 2 3.8

[0038] The above description of comparative examples is to facilitate those of ordinary skill in the art to understand and use the invention. Those skilled in the art can easily make various modifications to these examples, and apply the general principles described herein to other examples without creative labor. Therefore, the present application is not limited to the above examples, and improvements and modifications made by those skilled in the art based on the disclosure of the present application without departing from the scope of the present application should be within the scope of protection of the present application.

Claims

1. A method for preparing materials with improved interfacial properties in thermoplastic molding of polychlorotrifluoroethylene and a metal matrix, characterized in that, Includes the following steps: S1. The surface of polychlorotrifluoroethylene powder is modified by dopamine solution. After the reaction is completed, polychlorotrifluoroethylene modified by filtration or centrifugation is obtained. The concentration of the dopamine solution is 1–4 mg / mL; the pH value of the dopamine solution is 7.5–9.5, and the pH adjuster is tris(hydroxymethyl)aminomethane or ammonia. S2. The modified polychlorotrifluoroethylene is integrally molded with the metal matrix in a mold by hot pressing followed by cold pressing.

2. The preparation method for improving the interfacial properties of polychlorotrifluoroethylene and metal matrix thermoplastic molding according to claim 1, characterized in that, In step S1, the polychlorotrifluoroethylene powder has a size of 20 to 1000 mesh.

3. The preparation method for improving the interfacial properties of polychlorotrifluoroethylene and metal matrix thermoplastic molding according to claim 1, characterized in that, In step S1, the polychlorotrifluoroethylene powder is treated with dopamine solution for 2 to 48 hours, and the stirring speed is 100 to 500 rpm.

4. The preparation method for improving the interfacial properties of polychlorotrifluoroethylene and metal matrix thermoplastic molding according to claim 1, characterized in that, In step S1, the thickness of the polydopamine modified layer obtained after treating polychlorotrifluoroethylene powder with dopamine solution is 20-200 nm.

5. The preparation method for improving the interfacial properties of polychlorotrifluoroethylene and metal matrix thermoplastic molding according to claim 1, characterized in that, In step S2, the metal matrix is ​​stainless steel, aluminum, or GH4169 high-temperature alloy.

6. The preparation method for improving the interfacial properties of polychlorotrifluoroethylene and metal matrix thermoplastic molding according to claim 1, characterized in that, In step S2, the molding temperature of the polychlorotrifluoroethylene is 230-250°C, the molding pressure is 1-20 MPa, and the molding time is 15-90 min.

Images