A process for hot vulcanizing and bonding a PEEK composite shell to neoprene rubber.

Abstract

This invention discloses a process for hot vulcanizing and bonding a PEEK composite material shell to chloroprene rubber, belonging to the field of hot vulcanizing bonding technology for dissimilar materials. Using a flat vulcanizing machine, the PEEK composite material shell to be hot-vulcanized and bonded undergoes surface roughening, degreasing, and primer application before being placed into the mold cavity and the mold closed. A feeding tank is placed at the injection port of the upper mold, and an appropriate amount of chloroprene rubber is added into the feeding tank, with a plunger placed inside. The mold is then placed on the flat vulcanizing machine for preheating. Care must be taken to control the pressurization speed, pressurization pressure, and pressurization (injection) time, as well as to ensure the holding pressure and holding time. After the holding time is reached, the mold is opened and the product is removed. This invention is easy to operate, has a wide range of applications, and is suitable for various irregular PEEK composite material parts requiring high-strength bonding with chloroprene rubber.

Description

Technical Field

[0001] This invention relates to the field of thermal vulcanization bonding technology for dissimilar materials, specifically to a method for thermal vulcanization bonding of a PEEK composite material shell to chloroprene rubber. Background Technology

[0002] Polyetheretherketone (PEEK), as a new type of high-performance engineering plastic, has a high glass transition temperature and melting temperature, as well as advantages such as high elastic modulus, thermal stability, chemical stability, radiation resistance, low coefficient of friction, good wear resistance, and good load-bearing and meshing properties. Therefore, it is widely used in various industrial fields.

[0003] PEEK possesses excellent machinability. It can replace aluminum, titanium, and other metals, and can be easily processed into various complex shapes using injection molding, turning, milling, drilling, tapping, and CNC engraving processes based on customer drawings or samples. PEEK's low density and good machinability make it easy to machine into parts with extremely small tolerances, replacing other metal components.

[0004] Because PEEK also has good hydrolysis and corrosion resistance, it has excellent chemical stability against various liquids such as oil and acid, which can extend the service life of parts. It has shown great application prospects of "replacing steel with plastic", opening up new application areas for the plastics industry and opening up new ideas for the vulcanization bonding of plastics and rubber.

[0005] In the field of electronics and electrical engineering, PEEK also possesses excellent electrical properties. Even in harsh working environments such as high temperature, high pressure, and high humidity, it can still maintain excellent electrical insulation. Therefore, it is widely recognized as an ideal electrical insulation material in the electronics and electrical engineering field. It can be used for components such as plugs, high-reliability plugs, cable plugs, and junction boxes. Underwater electrical connectors made with PEEK not only meet the requirements of lightweight structural design but also contribute to the improvement of electrical insulation safety performance. PEEK does not deform within a wide temperature range. Based on this characteristic, PEEK is more suitable for manufacturing high-current, high-voltage connectors and high-temperature plugs.

[0006] With the continuous development and expansion of marine applications in my country, various types of underwater robots and underwater equipment have emerged. PEEK has excellent resistance to hydrolysis and corrosion, with a density of 1.26~1.38 g / cm³. 3As a type of "plastic steel," PEEK has a very low specific gravity, weighing only one-third that of stainless steel, and is slightly denser than water. It has important and widespread applications in key components that are in long-term contact with seawater, such as the housings of underwater plug-in connectors used in marine exploration and development, especially in seabed observation systems. Not only is it resistant to seawater corrosion, but its lightweight design also facilitates more convenient and flexible operation and target acquisition by the manipulators of remotely operated underwater vehicles (ROVs). Previously, PEEK had poor surface activity and poor adhesion to non-metals such as rubber. While acceptable for short-term use, with my country's continued development in the marine field, especially in deep-sea applications, the original stainless steel-rubber bonding process is prone to rusting or electrochemical corrosion of the stainless steel surface after prolonged seawater immersion, and the adhesive layer is prone to peeling off. This results in poor product reliability and is insufficient to meet the long-term use requirements of products in deep-sea environments. Summary of the Invention

[0007] The purpose of this invention is to provide a process for hot vulcanizing and bonding PEEK composite shells with chloroprene rubber. This method uses a flat vulcanizing machine to achieve hot vulcanization and bonding of PEEK composite shells with inserts and chloroprene rubber. The technology is mature, easy to operate, and suitable for hot vulcanization and bonding of various irregular PEEK composite shells with inserts and chloroprene rubber.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] A method for hot-curing bonding of a PEEK composite material shell to neoprene rubber, wherein the method uses a flat vulcanizing machine and a mold to bond the PEEK composite material shell and a plug together via neoprene rubber, the plug comprising connected copper contacts and a cable; the method specifically includes the following steps:

[0010] (1) The PEEK composite material shell and cable that need to be hot vulcanized are subjected to surface roughening treatment, degreasing treatment and brushing of adhesive in sequence;

[0011] (2) Place the shell after step (1) into the cavity of the mold and close the mold. Place the feeding tank at the injection port of the upper mold. Calculate the volume of the workpiece, put an appropriate amount of chloroprene rubber into the feeding tank and put the plunger on it. Place it on the flat vulcanizing machine for preheating.

[0012] (3) Heat bonding treatment: The mold is subjected to pressure and holding treatment in sequence, wherein: the pressure application speed is 0.15~0.4MPa / 5s, the pressure is 1.5~3MPa, the pressure (injection) time is 40~60s; the holding pressure is 1.5~3.5MPa, the holding time is 20~30min, and the mold is opened and the product is taken out after the holding time is up.

[0013] In step (1) above, the process of applying the base coat adhesive refers to applying the base coat adhesive to the degreased parts of the PEEK composite material shell and the cable. After applying the base coat adhesive, it is necessary to dry it in a drying oven at 60°C for 40 minutes to remove excess moisture from the base coat adhesive before applying the adhesive and vulcanizing it to improve the bonding strength.

[0014] In step (1) above, when applying the hot vulcanizing primer, the temperature should be controlled between 20℃ and 30℃, and the relative humidity should be less than or equal to 75%RH, so as to prevent residual moisture in the inner layer of the primer from causing vulcanization bonding failure.

[0015] In step (2) above, the mold includes an upper mold and a lower mold. The upper mold and the lower mold are fixed by screws after being closed. The upper mold is provided with a glue injection port. A feeding tank is placed at the glue injection port. The feeding tank contains chloroprene rubber compound for bonding.

[0016] In step (2) above, after the mold is closed and fixed, chloroprene rubber compound is added to the feeding tank and the mold is moved to the lower platen of the flat vulcanizing machine. When the upper platen is in contact with the upper part of the feeding tank, preheating is performed at a temperature of 130-160°C.

[0017] In step (2) above, the amount of chloroprene rubber to be added needs to be calculated based on the volume of the workpiece, so as to avoid excessive rubber injection causing the materials such as inserts, electrical contactors, wires, and cable cores inside the shell to be squeezed out, resulting in vulcanization failure.

[0018] The beneficial effects of this invention are:

[0019] 1. This invention uses a flat vulcanizing machine, which is inexpensive, easy to operate, and has a large operating space, making it suitable for scenarios where products with cables and inserts inside the PEEK composite material shell are bonded to rubber through hot vulcanization.

[0020] 2. Because a flat vulcanizing machine is used, and rubber vulcanizing molds are also used, the advantages are small size, light weight, low labor intensity, easier design, and low processing cost; unlike injection molds, which are large in size, heavy in weight, have high labor intensity, more complicated design mechanisms, and higher processing costs.

[0021] 3. Because PEEK combines the advantages of both metal and plastic, and is a top-tier environmentally friendly material, its environmental performance has opened up new application areas for the plastics industry, and in some areas it can even replace stainless steel.

[0022] 4. After the product is roughened on the surface, use medical tweezers to pick up degreased cotton and clean it with ethyl acetate solution to activate the surface to be bonded. Before applying the adhesive, apply a layer of low-viscosity hot vulcanizing primer. The two layers of adhesive can completely wet the surface of the PEEK composite shell, increase the wetting angle, increase the bonding area between PEEK and neoprene rubber, and achieve better adhesion and higher bonding strength.

[0023] 5. Wide range of applications, suitable for both terrestrial and deep-sea environments, and lightweight structural design, such as the application of PEEK composite materials and neoprene rubber through heat vulcanization bonding.

[0024] 6. During the hot vulcanization bonding process of this invention, it is essential to control the pressurization speed, pressurization pressure, and pressurization (injection) time, as well as ensure the accuracy and stability of process parameters such as holding pressure and holding time, so as to avoid affecting the final bonding strength between the PEEK composite shell and the neoprene rubber due to inaccurate parameter control.

[0025] 7. The preheating time of the parts and molds of this invention should not be too long to prevent the base coating from failing, otherwise it will easily lead to insufficient vulcanization bonding strength and failure. Attached Figure Description

[0026] Figure 1 This invention provides a watertight plug made by vulcanizing and bonding a PEEK composite material shell to neoprene rubber, as described in one embodiment.

[0027] Figure 2 This is a schematic diagram showing the placement of the material feeding tank in the upper mold after the plug body is molded.

[0028] Figure 3 This is a schematic diagram of the entire mold being vulcanized by injection of adhesive on the vulcanizing machine plate. Detailed Implementation

[0029] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0030] This embodiment features a watertight plug combining a PEEK composite material shell with inserts and neoprene rubber. The hot vulcanization bonding process is as follows:

[0031] 1. The outer wall of the PEEK composite shell 11 where it needs to be vulcanized and bonded to the neoprene rubber is mechanically ground to ensure uniform surface roughness.

[0032] 2. Tin-plat the inner wall of the copper contact 12 welding cup. After stripping and tin-plating the cable 13, weld it one-to-one with the copper contact 12. Use a homemade wood file to polish the parts of the cable that need to be vulcanized, and make sure the surface roughness is uniform.

[0033] 3. Use medical tweezers to hold a piece of degreased cotton soaked in ethyl acetate solution and degrease the ground area of ​​the PEEK composite shell twice. Then set it aside to air dry at room temperature for 10 minutes.

[0034] 4. Use medical tweezers to apply acetone-soaked cotton to the polished area of ​​cable 13 twice to remove the grease, then set it aside to air dry at room temperature for 10 minutes.

[0035] 5. Apply a layer of primer I14 to the degreased areas of the PEEK composite material using a soft brush. Primer I contains organic hydrocarbon polymer and silicon dispersion filler at mass fractions of 70% and 20% respectively, and xylene at a mass fraction of 10%. The coating should be applied evenly and with a consistent thickness, ensuring no liquid flow on the shell surface. The coating thickness should be between 12.7 and 25.4 μm. Then, place it in a 60°C forced-air drying oven for 40 minutes to thoroughly remove excess moisture from the primer. Afterward, measure the coating thickness using a film thickness gauge. If it passes the test, proceed to the next step.

[0036] 6. Apply a layer of the prepared primer adhesive II15 to the sanded area of ​​the cable using a soft brush. The primer adhesive II formula contains 40% polyisocyanate, 50% cyclohexanone (a volatile compound), and 10% adhesive powder. The coating should be applied evenly and with a consistent thickness, until no liquid flows from the outer sheath of the cable 13. The coating thickness should be between 12.7 and 25.4 μm. Then, place it in a 60°C forced-air drying oven for 40 minutes to thoroughly remove excess moisture from the primer adhesive. After that, measure the coating thickness with a film thickness gauge. If it passes the test, apply another layer of primer adhesive II15 according to the above process. If it passes the test, proceed to the next step.

[0037] 7. Using a soft brush, apply a layer of primer I14 to the PEEK composite material, followed by a layer of the prepared topcoat 16. The topcoat formulation contains organic hydrocarbon polymer and silicon dispersed filler, with mass fractions of 65% and 20% respectively, and a mass fraction of xylene (volatile substance) of 15%. The coating should be applied evenly and with a consistent thickness, ensuring no liquid flow on the shell surface. The coating thickness should be between 12.7 and 25.4 μm. Then, place it in a 60°C forced-air drying oven for 40 minutes to thoroughly remove excess moisture from the topcoat. Afterward, measure the coating thickness with a film thickness gauge. If it passes the test, apply another layer of topcoat 16 according to the above process. If it passes the test, proceed to the next step.

[0038] 8. Place the entire plug into cavity 17 of the mold (see...) Figure 1 ).

[0039] 9. After the upper and lower molds are closed, place hex screws 21 at the four corners of the mold and tighten them with an hex wrench. Place the filling can 22 at the injection port of the upper mold (see...). Figure 2Based on the volume of the workpiece, approximately 20g of chloroprene rubber compound is added to the feeding tank and transferred to the flat vulcanizing machine (see...). Figure 3 On the lower plate 31, start the oil pump to raise the oil cylinder 33. When the upper plate 32 is in contact with the plunger of the feeding tank, turn off the oil pump to preheat. The preheating conditions are 150℃ and the preheating time is 3 minutes. The purpose is to increase the fluidity of the compound rubber and facilitate subsequent injection vulcanization.

[0040] 10. After the preheating time is up, start the oil pump again and perform vulcanization according to the process parameters such as pressurization (injection) time, pressurization speed, pressurization pressure, holding time and holding pressure, as shown in Table 1 below. After vulcanization is completed, open the mold and take out the product.

[0041] Table 1 Vulcanization process parameters

[0042] vulcanization temperature 150℃ pressurization time 50s Pressurization pressure 2MPa pressurization rate 0.2MPa / 5s Pressure holding time 25min Holding pressure 2MPa

[0043] After vulcanization, inspect Figure 1 The cavity 17 shown in the diagram is filled with neoprene rubber, which is firmly bonded to the PEEK composite material shell 11 and the cable 13. Actual measurements show that the shear strength of neoprene rubber and the PEEK shell can reach over 10 MPa (the shear strength of ordinary stainless steel and neoprene rubber after vulcanization is only about 8 MPa). Specifically, the shell 11 used for the plug is made of PEEK composite material, and the outer sheath of the cable 13 is made of neoprene rubber or polyurethane.

[0044] This invention avoids the defects such as poor adhesion and easy detachment that occur when using PEEK composite materials with inserts in the shell during vulcanization with neoprene rubber. The reliability and stability of the quality are guaranteed, meeting the chemical corrosion resistance requirements of the underwater pluggable electrical connector shell under deep-sea conditions where it is in contact with seawater for a long time. Moreover, the lightweight design facilitates easier and more flexible operation and target grasping by the manipulator of underwater robots. The product's water pressure resistance can reach 60MPa. The wear resistance and scratch resistance of the PEEK composite material shell also meet the usage requirements of complex environments such as various seabed topography.

Claims

1. A process for hot vulcanizing and bonding a PEEK composite material shell to chloroprene rubber, characterized in that: This method uses a flat vulcanizing machine and a mold to bond a PEEK composite material shell that requires heat vulcanization to neoprene rubber. The PEEK composite material shell includes connected copper contacts and cables. The method specifically includes the following steps: (1) The PEEK composite material shell and the cable that need to be hot vulcanized are subjected to surface roughening treatment, degreasing treatment and bottom coating process in sequence; wherein the bottom coating process of the PEEK composite material shell includes first applying a layer of bottom coating, and after it dries, applying two layers of top coating. The bottom coating contains 70% organic hydrocarbon polymer, 20% silicon dispersed filler and 10% xylene by mass, and the top coating contains 65% organic hydrocarbon polymer, 20% silicon dispersed filler and 15% xylene by mass. (2) Place the shell after step (1) into the cavity of the mold and close the mold. Place the feeding tank at the injection port of the upper mold. Calculate the volume of the workpiece, put an appropriate amount of chloroprene rubber into the feeding tank and put the plunger on it. Place it on the flat vulcanizing machine for preheating. After the mold is closed and fixed, add chloroprene rubber into the feeding tank and move the mold to the lower plate of the flat vulcanizing machine. When the upper plate is in contact with the upper part of the feeding tank, preheat the mold. The preheating temperature is 130-160℃. (3) Heat bonding treatment: The mold is subjected to pressure and holding treatment in sequence, wherein: the pressure application speed is 0.15~0.4MPa / 5s, the pressure is 1.5~3MPa, and the pressure application time is 40~60s; the holding pressure is 1.5~3.5MPa, and the holding time is 20~30min. After the holding time is up, the mold is opened and the product is taken out.

2. The process for hot-curing bonding of the PEEK composite material shell to chloroprene rubber according to claim 1, characterized in that: In step (1), the process of applying the base coat adhesive refers to applying the base coat adhesive to the degreased parts of the PEEK composite material shell and the cable. After applying the base coat adhesive, it is necessary to dry it in a drying oven at 60°C for 40 minutes to remove excess moisture from the base coat adhesive before applying the adhesive and vulcanizing it to improve the bonding strength.

3. The process for hot-curing bonding of the PEEK composite material shell to chloroprene rubber according to claim 1, characterized in that: In step (1), when applying the hot vulcanizing primer, the temperature should be controlled between 20℃ and 30℃, and the relative humidity should be less than or equal to 75%RH.

4. The process for hot-curing bonding of the PEEK composite material shell to chloroprene rubber according to claim 1, characterized in that: In step (2), the mold includes an upper mold and a lower mold, which are fixed together by screws; the upper mold is provided with an injection port, and a feeding tank is placed at the injection port, with neoprene rubber for bonding placed inside the feeding tank.

5. The process for hot-curing bonding of the PEEK composite material shell to chloroprene rubber according to claim 1, characterized in that: In step (2), the amount of chloroprene rubber to be fed needs to be calculated based on the volume of the workpiece.

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