WO2020082678A1 - Wear-resistant self-crosslinking nano coating and preparation method thereof - Google Patents

Abstract

A preparation method of a wear-resistant self-crosslinking nano coating, including exposing a substrate to a monomer steam atmosphere and performing plasma discharge to carry out a chemical vapor deposition reaction on a surface of the substrate, thereby forming the nano coating. The monomer is a fluorocarbon resin containing phenyl and acrylate groups. Also provided is a wear-resistant self-crosslinking nano coating.

Description

Wear-resistant self-crosslinking nano-coating and preparation method thereof Technical field

The invention relates to the technical field of plasma chemical vapor deposition, in particular to a wear-resistant self-crosslinking nano-coating and a preparation method thereof.

Background technique

The intrusion of liquid and moisture is one of the most important causes of PCB board corrosion and short circuit in electronic devices. Polymer coatings are often used for the protection of material surfaces due to their advantages such as economy, easy coating, wide application range, and good chemical resistance. The polymer coating blocks the intrusion of liquids, especially water and steam, thereby improving the adaptability of electronic devices in a humid environment, and making important product indicators such as quality stability and reliability, service life of electronic devices to a great extent improve. At present, there are two main methods for applying a protective layer on the PCB board: depending on the state of the material: liquid phase coating and vapor deposition. Liquid phase coating, such as three-proof paint, the construction method can use dipping method, brushing method, spraying method and other processes, the liquid phase raw material is applied on the surface of the substrate and then thermally cured, light cured and other means to form dense, cross-linked Polymer coating. However, the liquid-phase coating method generates a large amount of exhaust gas and waste liquid, and the raw material utilization rate is low. At the same time, the solvent used often causes certain damage to the PCB of the electronic device; in addition, the thickness of the three anti-paint is more than tens of microns The uniformity of the thickness is poor, which has a great impact on the functions of some electronic devices that require heat dissipation and signal transmission. In contrast, the vapor deposition method, especially the plasma chemical vapor deposition method, is a method that uses plasma to activate the reaction gas and perform chemical vapor deposition on the surface of the substrate. This method is suitable for the protection requirements of various substrate surfaces: vapor-phase coating can be uniformly deposited on substrates of different shapes; the coating preparation temperature is low, suitable for the protection of temperature-sensitive devices; the coating is thin and the stress is small, Less damage to PCB. Because the plasma coating process can prepare ultra-thin nano-scale coatings, it has almost no effect on the heat dissipation and conductivity of electronic devices. At present, the main protective materials used on PCBs are fluorocarbon resins, but the fluorocarbon resins are relatively low in strength, easy to slide and deform under the action of external forces, and are not resistant to friction. The intermolecular cross-linking method can increase the force between the fluorocarbon resin layer and the layer, make the coating more dense, and enhance the protection ability of the coating against wear and corrosion. CN107058979 "Preparation method of waterproof and electrical breakdown resistant coating" In the fluorocarbon resin monomer, multifunctional unsaturated hydrocarbon derivatives are introduced to improve the product's resistance to corrosion and underwater energization. However, because the fluorocarbon resin monomer is a fatty chain, the rigidity is poor, and the wear resistance is still difficult to meet the requirements for use. Therefore, how to control the rigidity of molecules through the design of molecular structure to further improve the strength and wear resistance of nano-coatings is an important direction for the optimization and improvement of nano-coatings.

Summary of the invention

The present invention is to overcome the above shortcomings and provide a method for preparing a wear-resistant self-crosslinking nano-coating. The present invention uses plasma chemical vapor deposition technology to introduce self-crosslinks between fluorocarbon resins by introducing rigid benzene rings into the monomers of fluorocarbon resins and introducing functional groups on the benzene rings that can be used to form crosslinking points through chemical reactions The body-shaped network structure improves the strength and wear resistance of the nano-coating.

The present invention is achieved through the following technical solutions:

A method for preparing a wear-resistant self-crosslinking nano-coating, characterized in that: the substrate is exposed to a monomer vapor atmosphere, and a chemical vapor deposition reaction is initiated on the surface of the substrate by plasma discharge to form a protective coating;

The monomer vapor is a monomer having a structure represented by formula (I):

In formula (I), R ¹ , R ² and R ^{3 are} independently selected from hydrogen, alkyl, aryl, halogen or haloalkyl;

R ^{4 is} selected from one of a bond, an alkyl subunit, an aryl subunit, and a hydrocarbyl subunit; R ⁵ , R ⁶ , and R ^{7 are} independently selected from hydrogen, halogen, alkyl, hydroxyl, alkenyl, and diene Group, amino group, aldehyde group, amino group, carboxyl group, acid anhydride or mercapto group, R ^{8 is} selected from one of hydroxyl, alkenyl, dienyl, amino, carboxyl group, acid anhydride, mercapto group, halogen. m is an integer of 0-10, n is an integer of 0-20, and p is an integer of 1-10. X is hydrogen or halogen.

It should be noted that in the present invention, R ¹ , R ² , and R ³ may be a group connected to an unsaturated carbon-carbon double bond, or may be a group having good hydrophobic properties. R ⁴ is a bridging group between the reactive functional group and the functional group. R ⁵ , R ⁶ and R ⁷ are groups connected to the benzene ring. R ⁸ is a group that can undergo further reaction under the action of plasma to form a cross-linked structure between molecules. X is hydrogen or a substituent on a hydrophobic carbon chain.

Further, R ⁴ is a short bridge group, which is a bond or a methylene group, and the groups R ⁵ and R ⁶ on the benzene ring are hydrogen, and R ⁷ is hydrogen or halogen.

Further, R ⁸ is a substituent that can form a reactive group under low power discharge, and is selected from one of vinyl group, 1-butadienyl group, halogen, and hydroxyl group.

Further, the monomer is a liquid at normal temperature and pressure, m is 0, 1, 2, or 3, and n is 1, 3, 5, 6, 7, or 8.

Further, R ⁸ is a carbon-carbon unsaturated bond, preferably vinyl.

Further, the substrate is a solid material such as metal, optical instrument, clothing fabric, electronic device or medical device.

The invention also discloses a method for preparing a wear-resistant self-crosslinking nano coating, which comprises the following steps:

(1) Inside the reaction chamber of the substrate plasma chamber, evacuate the reaction chamber to 1 mtorr-100 torr;

(2) Into the plasma source gas, start the plasma discharge, the monomer after vaporization into the reaction chamber for chemical vapor deposition reaction;

(3) Turn off the plasma discharge, pass clean compressed air or inert gas, the cavity returns to normal pressure, open the vacuum cavity, and take out the substrate.

Further, the plasma source gas is helium gas, and the flow rate is 1-500 sccm.

Further, the temperature of the plasma chamber in step (2) is controlled at 30-60 ° C.

Further, in step (2), the vaporization temperature of the monomer is 60 ° C-150 ° C, and the vaporization is under reduced pressure.

Further, in step (2), the monomer is vaporized under a vacuum of 0.1 mtorr to 100 torr.

Further, the plasma discharge method is radio frequency discharge, microwave discharge, intermediate frequency discharge, Penning discharge or electric spark discharge.

Further, the plasma discharge is a microwave discharge with a frequency of 500MHz-300KMHz.

Further, the plasma discharge time is 10s-14400s.

Compared with the prior art, the present invention introduces a rigid benzene ring into the monomer of the fluorocarbon resin and introduces a functional group on the benzene ring that can be used for chemical reaction to form a cross-linking point, so that the fluorocarbon resin forms a bulk network structure , Increase the density of the coating, improve the hardness and wear resistance of the coating. The invention adopts the plasma nano-coating technology to initiate the reaction between different functional groups, avoiding the difficulty of selecting the conventional chemical reaction catalytic path, the coating process is easy to control, and the stability of the coating quality is greatly improved.

detailed description

Example 1

A preparation method of wear-resistant self-crosslinking nano-coating, after the following steps:

(1) Place the rear-view lens of the car in the reaction chamber of the plasma chamber, continuously evacuate the reaction chamber to 1 mtorr, pass the plasma source gas, and start the plasma discharge;

(2) The monomer S1 is vaporized and then introduced into the reaction chamber for chemical vapor deposition reaction;

(3) After the discharge is completed, compressed air is introduced to return the chamber to normal pressure, the vacuum chamber is opened, and the substrate is taken out.

Among them, the plasma source gas is helium, the flow rate is 50 sccm, and the temperature of the plasma chamber is controlled at 30 ° C. The vaporization temperature of the monomer is 60 ° C. The monomer is vaporized under a vacuum of 1 mTorr, the monomer inflow rate is 250 μL / min, and the infusion time is 3000 s. The plasma discharge is a microwave discharge with a frequency of 500MHz.

Among them, more preferably, the plasma discharge in this embodiment may be divided into two stages, namely, a pretreatment stage before the monomer is introduced and a deposition stage after the monomer is introduced. The discharge power in the pretreatment stage is 2-500W, and the continuous discharge time is 1-3600s. The discharge method in the deposition stage can be the same as in the pretreatment stage, or it can be changed. The discharge time continues until the end of the deposition.

Example 2

Compared with Example 1, step (1) is evacuated to 100 mtorr; in step (2), monomer S1 is replaced with monomer S2, the vaporization temperature of the monomer is 120 ° C, the vaporization vacuum is 200 mtorr, the monomer The access time is 3500s, and other conditions remain unchanged.

Example 3

Compared with Example 1, step (1) is evacuated to 50 mtorr; in step (2), monomer S1 is replaced with monomer S3, the vaporization temperature of the monomer is 80 ° C, the vaporization vacuum is 70 mtorr, the monomer The access time is 4000s, and other conditions remain unchanged.

Example 4

Compared with Example 1, step (1) is evacuated to 60 mtorr; in step (2), monomer S1 is replaced with monomer S4, the vaporization temperature of the monomer is 100 ° C, the vaporization vacuum is 90 mtorr, the monomer The access time is 4000s, and other conditions remain unchanged.

Example 5

Compared with Example 1, step (1) is evacuated to 60 mtorr; in step (2), monomer S1 is replaced with monomer S5, the vaporization temperature of the monomer is 100 ° C, the vaporization vacuum is 70 mtorr, the monomer The access time is 7200s, other conditions remain unchanged.

Example 6

Compared with Example 1, the temperature of the plasma chamber is controlled at 50 ° C, and other conditions remain unchanged.

Example 7

Compared with Example 2, the microwave discharge frequency is changed to 10 KMHz, and other conditions remain unchanged.

Example 8

Compared with Example 2, the monomer flow rate was changed to 400 μL / min, and other conditions remained unchanged.

Example 9

Compared with Example 2, the flow rate of helium gas was changed to 20 μL / min, and other conditions remained unchanged.

Comparative Example 1

Compared with Example 2, the monomer S2 was replaced with 2- (perfluorohexyl) ethyl methacrylate.

Comparative Example 2

Compared with Example 2, the monomer S2 was replaced with 2- (perfluorobutyl) ethyl acrylate. The substrate after the above examples was plated, and the coating thickness, water contact angle, pencil hardness level, resistance Abrasive test.

The thickness of the nano-coating is tested using the US Filmetrics-F20-UV-film thickness measuring instrument.

Nano-coating water contact angle is tested according to GB / T 30447-2013 standard.

The pencil hardness test method is based on ASTM D3363 pencil hardness.

The abrasion resistance test is conducted in an alcohol abrasion tester. The eraser test fixture is selected for the test. The test condition is a load of 100g, a rotation speed of 60cycle / min, and the number of cycles when the coating is damaged.

Table 1

The monomer used in this technical solution introduces a rigid group benzene ring and a multifunctional group that can be used for cross-linking, so that the role between the molecular chains during the formation of the coating is stronger, the density of the coating is improved, and then the wear resistance and The hardness level of the coating has been significantly improved.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention, rather than limiting it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: The technical solutions described in the foregoing embodiments can still be modified, or some or all of the technical features can be equivalently replaced; and these modifications or replacements do not deviate from the essence of the corresponding technical solutions of the technical solutions of the embodiments of the present invention. range.

Claims (13)

A wear-resistant self-crosslinking nano-coating, characterized in that the substrate is exposed to the atmosphere of monomer vapor, and a chemical vapor deposition reaction is initiated on the surface of the substrate by plasma discharge to form a protective coating; The monomer vapor is a monomer having the structure represented by formula (I): the substrate is exposed to the monomer having the structure represented by formula (I), and a chemical deposition reaction occurs on the surface of the substrate by plasma means to form a protective coating Floor:

Wherein R ¹ , R ² and R ^{3 are} independently selected from hydrogen, alkyl, aryl, halogen or haloalkyl; R ⁴ is one of a bond, alkyl subunit, aryl subunit or hydrocarbyl subunit; R ⁵ , R ⁶ , and R ^{7 are} independently selected from hydrogen, halogen, alkyl, hydroxy, alkenyl, dienyl, amino, aldehyde, amino, carboxy, anhydride, or mercapto, R ⁸ is hydroxy, alkenyl, di One of alkenyl, amino, carboxyl, anhydride, mercapto or halogen, m is an integer of 0-10, n is an integer of 0-20, p is an integer of 1-10, X is hydrogen or halogen. The wear-resistant self-crosslinking nano-coating according to claim 1, wherein R ₄ is a bond or methylene group, R ⁵ and R ⁶ are hydrogen, and R ⁷ is hydrogen or halogen. The wear-resistant self-crosslinking nano-coating according to claim 1, wherein R ⁸ is one of vinyl group, 1-butadienyl group, halogen or hydroxyl group. A wear-resistant self-crosslinking nano-coating according to claim 1, wherein m is 0, 1, 2 or 3, and n is 1, 3, 5, 6, 7 or 8. A wear-resistant self-crosslinking nano-coating according to claim 3, wherein R ⁸ is vinyl. The method for preparing a wear-resistant self-crosslinking nano-coating according to claim 1, comprising the following steps: (1) Inside the reaction chamber of the substrate plasma chamber, evacuate the reaction chamber to 1 mtorr-100 torr; (2) Into the plasma source gas, start the plasma discharge, the monomer after vaporization into the reaction chamber for chemical vapor deposition reaction; (3) Turn off the plasma discharge, pass clean compressed air or inert gas, the cavity returns to normal pressure, open the vacuum cavity, and take out the substrate. The method for preparing a wear-resistant self-crosslinking nano-coating according to claim 6, wherein the plasma source gas is helium gas and the flow rate is 1-500 sccm. The preparation method of wear-resistant self-crosslinking nano-coating according to claim 6, characterized in that the temperature of the plasma chamber in step (2) is controlled at 30-60 ° C. The method for preparing a wear-resistant self-crosslinking nano-coating according to claim 6, characterized in that, in step (2), the vaporization temperature of the monomer is 60 ° C-150 ° C, and it is vaporization under reduced pressure. The preparation method of wear-resistant self-crosslinking nano-coating according to claim 9, characterized in that, in step (2), the monomer is vaporized under the condition of a vacuum of 0.1 mtorr to 100 torr. The method for preparing a wear-resistant self-crosslinking nano-coating according to claim 6, wherein the plasma discharge method is radio frequency discharge, microwave discharge, intermediate frequency discharge, penning discharge or electric spark discharge . The preparation method of wear-resistant self-crosslinking nano-coating according to claim 6, characterized in that the plasma discharge is microwave discharge and the frequency is 500MHz-300KMHz. The method for preparing a wear-resistant self-crosslinking nano-coating according to claim 12, wherein the plasma discharge time is 10s-14400s.