TW202016348A - An epoxy nano coating and preparation method thereof - Google Patents

Abstract

The present invention provides an epoxy nanocoating and preparation method thereof, which exposes a substrate to a monomer of the present invention, and chemically reacts on the surface of the substrate by plasma discharge to form a protective coating. The invention utilizes the plasma technology to initiate the polymerization reaction of the epoxy compound, and by controlling the process conditions such as the monomer flow rate and the plasma discharge power, the destruction of the structural integrity of the monomer molecule by the high-power discharge means is avoided. At the same time, the problem that the epoxide explosion is caused to cause heat dissipation is avoided.

Description

Epoxy nano coating and preparation method thereof

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

Epoxy compound refers to a compound containing oxirane, which contains ether bond in the main chain after ring-opening polymerization, and has excellent chemical resistance, especially acid resistance, alkali resistance and oxidation resistance. In addition, the epoxy compound has good adhesion to the surface of many substrates, especially the metal surface. After cross-linking, the rigidity is strong, heat-resistant, and wear-resistant; the compound contains a three-membered ring ether structure, high tension, and a tendency to open ring thermodynamically It is very large and easy to form polymers, so epoxy resins are widely used in the coating industry. CN102229777 A "A hydrophobic and oleophobic epoxy coating and its preparation and use method" By introducing low surface energy substances and nanoparticles, using the principle of micro-phase separation, the prepared epoxy coating has strong hydrophobic and oleophobicity and is in contact with water The angle can reach 149°, and the contact angle to oil is up to 101°. The preparation method and use method are as follows: In the first step, fluorine-containing acrylate, vinyl-containing triethoxysilane, styrene and other raw materials are mixed according to a certain mass ratio to prepare fluorine through demulsification, water washing and drying. Silicon copolymer; the second step is to mix the epoxy color paint, prepared fluorosilicone copolymer, mixed solvent, nano calcium dioxide, curing agent and other raw materials according to the mass ratio of the input to prepare a low surface energy epoxy coating; the third step ，Apply the low surface energy epoxy coating on the surface of the substrate, and cure at 50℃ for 1~5h, then heat up to 120℃~200℃ and cure for 1~5h. The preparation process of this method is complicated, and the use of multiple organic solvents in the formulation is prone to pollution. CN 107694881 A "A method for improving the bonding strength of an epoxy coating" provides a method for increasing the bonding strength of an epoxy coating, that is, before applying epoxy resin on the surface of the substrate, it is treated with atmospheric air plasma, Bombing oil stains, adsorbents, etc. from the surface of the substrate away from the surface, increasing the roughness of the surface of some materials, increasing the effective adhesion area and wetting surface area of the coating and the substrate. Within 2 hours after the plasma treatment of the substrate surface, the epoxy coating was prepared by brush coating, spray coating or fluidized bed method. As mentioned in these two patents, the current construction process of epoxy resins is to perform liquid phase coating on the surface of the substrate, and then use curing means to further crosslink the coating material to form a protective coating, the film thickness is generally in the tens of dozens Micron or more. However, at this thickness, the barrier properties of the coating itself can easily lead to poor heat dissipation and conductivity of the substrate. Especially when used in places where electronic signal requirements are high, such as electronic component interfaces, the electronic signal of the processed product is greatly attenuated and cannot be used normally; the construction process also determines the presence of these epoxy coatings. The situation where the surface coverage is uneven and part of the device cannot be effectively protected by the coating. Using the plasma film forming method, the thickness of the epoxy polymer coating can be accurately controlled in the nanometer and micrometer range while maintaining the strength and bonding force of the epoxy polymer coating.

In order to overcome the above shortcomings, the present invention provides a method for preparing epoxy resin nano-coating by using plasma chemical vapor deposition technology and the nano-coating obtained by this method. The invention also provides a method for preparing a high-adhesion coating under low power.

The present invention is achieved through the following technical solutions:

An epoxy nano-coating, characterized in that the substrate is exposed to a monomer having the structure shown in formula (I), and a chemical reaction occurs on the surface of the substrate by plasma means to form a protective coating:

（I）monomer:

(I)

Wherein, R ¹ , R ² and R ³ are groups connected to the three-membered ring, and are independently selected from hydrogen, alkyl, aryl, halogen, haloalkyl or hydroxy; m is an integer of 0-8 and n is 1- An integer of 15. The power supply characteristics and group size of the groups R ¹ , R ² and R ³ on the three-membered ring have an important influence on the stability and ring-opening tendency of the three-membered ring. Alkyl, aryl, haloalkyl can be used as a power supply group to stabilize the three-membered ring, while hydroxyl, halogen and other electron-withdrawing groups will further enhance the electron-positive carbon atoms in the three-membered ring. The ring-opening polymerization can be rapidly initiated under the plasma.

Further, R ¹ , R ² and R ³ are hydrophobic groups and are independently selected from hydrogen, alkyl, halogen or haloalkyl.

Further, the halogen is fluorine, and the haloalkyl group is a perfluoroalkyl group having 1 to 10 carbon atoms. The fluoroalkyl group may be linear or may contain branched chains.

Further, when X is hydrogen or halogen, since the carbon-hydrogen and carbon-halogen bond energies are high, the monomer structure is relatively stable and the chemical resistance is excellent. In addition, when X is preferably fluorine, the interaction force between fluorine atoms is large, the C-F bond is symmetrically distributed around the entire molecule, so that the surface energy of the molecule is very low, and the coating obtained by polymerization has good hydrophobicity.

When m>5, n>10, the boiling point of the monomer is higher, which is not conducive to vaporization. Preferably, m is 0, 1, 2, or 3, and n is an integer of 1-8.

The epoxy nano-coating can be used to protect the surfaces of different substrates against chemical corrosion and hydrophobicity. The substrate can be solid materials such as metals, optical instruments, clothing fabrics, electronic devices, and medical devices.

The invention also discloses a preparation method of the nano coating layer including the following steps:

(1) Place the substrate in the reaction chamber of the plasma chamber, and evacuate the vacuum in the reaction chamber to 0.1-1000 mTorr;

(2) Into the plasma source gas, start the deposition and use plasma discharge to vaporize the monomer into the reaction chamber for chemical vapor deposition reaction;

(3) Turn off the plasma discharge for deposition, pass clean compressed air or inert gas to return to normal pressure, open the cavity, and remove the substrate.

The monomer is introduced into the reaction chamber after being vaporized under reduced pressure.

Further, the plasma source gas in step (2) may be one or a mixture of several kinds of helium, argon, nitrogen, and hydrogen.

Further, the volume of the plasma chamber is 1L-2000L, the flow rate of the plasma source gas is 1-1000sccm, and the flow rate of the monomer vapor is 1-2000μL/min.

Further, in the step (2), after passing the plasma source gas and before the deposition plasma discharge, a plasma discharge step for pretreatment of the substrate is further included.

After the plasma source gas is introduced in step (2), the pretreatment plasma discharge is turned on and the substrate is pretreated first. The power of plasma discharge in this pretreatment stage is 1-1000W, and the continuous discharge time is 1-6000s.

After the pretreatment phase is completed, the deposition phase is entered (the plasma discharge for pretreatment is converted to a plasma discharge for deposition). The plasma discharge method and parameters of the two phases may be the same or different.

Further, in the step (2), the power of the plasma discharge for deposition during the introduction of the monomer into the cavity is 2-500 W, and the continuous discharge time is 600-18000 s.

More preferably, the plasma discharge power for deposition is preferably 2-50W.

Further, the plasma discharge (plasma discharge for pretreatment and/or plasma discharge for deposition) is radio frequency discharge, microwave discharge, intermediate frequency discharge, Penning discharge or electric spark discharge.

Further, the plasma discharge (plasma discharge for pretreatment and/or plasma discharge for deposition) is a radio frequency discharge, and the energy output method for controlling the plasma radio frequency during the radio frequency discharge is pulse or continuous output. When the energy output mode is pulse output, the pulse width is 10μs-50ms and the repetition frequency is 20Hz-10kHz.

Compared with the prior art, the monomer polymerization mechanism of the present invention is based on epoxy ring opening, and the plasma power required for excitation is low, which avoids the destruction of the monomer molecular structure integrity by high-power discharge means. The invention adopts an epoxy compound with good adhesion to the substrate, which greatly improves the binding force between the nano coating and the substrate. The invention uses the plasma technology to initiate the polymerization reaction of the epoxy compound. By controlling the process conditions such as monomer flow rate and plasma discharge power, the problem of difficulty in heat dissipation caused by the explosive polymerization of the epoxide is avoided.

Examples 1

An epoxy nano-coating and its preparation method go through the following steps:

(1) Place the iron block in the 200L plasma vacuum reaction chamber, and continuously evacuate the reaction chamber to achieve a vacuum of 0.8 mtorr.

(2) Introduce helium gas with a flow rate of 50sccm. Turn on the RF plasma discharge to pretreat the iron base material (that is, turn on the RF pretreatment plasma discharge). The discharge power in the pretreatment stage is 20W, and the continuous discharge is 100. s.

(3) The monomer S1 is passed through the chemical vapor deposition on the surface of the substrate to prepare a nano-coating, the monomer flow rate is 150 μL/min, after 1 mtorr high vacuum vaporization, it is passed into the reaction chamber, and the passing time is 2000s . The plasma discharge for pretreatment is adjusted to the plasma discharge for deposition. The plasma in the deposition stage is generated by radio frequency discharge, the output mode is pulse, the pulse width is 5 μs, the repetition frequency is 3000 Hz, the discharge power is 10 W, and the discharge time is 2000 s.

(4) After the coating preparation is completed, nitrogen gas is introduced to restore the reaction chamber to normal pressure, the chamber is opened, and the metal iron block is removed.

(5) Test the protective properties of the sample coating, including the thickness of the coating, hydrophobicity (water contact angle), chemical corrosion resistance, coating adhesion, and contact resistance.

Monomer S1

Among them, the plasma discharge device for pretreatment and the plasma discharge device for deposition may be one set or two separate sets. The plasma discharge device (for example, electrode) for pretreatment is preferably arranged in the reaction chamber and around the base material, so as to facilitate the quick connection with the coating process after pretreatment; the plasma discharge device for deposition can be arranged in the reaction chamber It is installed outside and away from the reaction chamber, so as to avoid the negative influence of the plasma discharge on the substrate during the coating process selectively or as far as possible.

Examples 2

An epoxy nano-coating and its preparation method go through the following steps:

(1) Place the magnesium alloy in the 800L plasma vacuum reaction chamber, and continuously evacuate the reaction chamber to achieve a vacuum of 50 mTorr.

(2) Introduce helium gas with a flow rate of 50sccm. Turn on the radio frequency plasma discharge to pretreat the magnesium alloy substrate (that is, turn on the radio frequency mode pretreatment plasma discharge). The discharge power in the pretreatment stage is 20W, and the continuous discharge is 100 s.

(3) The monomer S2 is passed through the chemical vapor deposition on the surface of the substrate to prepare a nano-coating, the monomer flow rate is 300 μL/min, after 10 mTorr high vacuum vaporization, it is passed into the reaction chamber, and the passing time is 2500s . The plasma discharge for pretreatment is adjusted to the plasma discharge for deposition.

The plasma in the deposition stage is generated by radio frequency discharge, the output mode is pulse, the pulse width is 100 μs, the repetition frequency is 5000 Hz, the discharge power is 20 W, and the discharge time is 2500 s. (4) After the coating preparation is completed, nitrogen gas is introduced to restore the reaction chamber to normal pressure, the chamber is opened, and the magnesium alloy is taken out. (5) Test the protective properties of the sample coating, including the thickness of the coating, hydrophobicity (water contact angle), chemical resistance, coating adhesion, and contact resistance.

Monomer S2

Examples 3

Compared with Example 1, step (1) was evacuated to 100 mtorr; in step (2), monomer S1 was replaced with monomer S3, and step (3) monomer inlet time and discharge time were replaced with 3000s, other conditions the same.

Single S3

Examples 4

Compared with Example 1, step (1) was evacuated to 150 mtorr; in step (2), monomer S1 was replaced with monomer S4, and step (3) monomer inlet and discharge times were replaced with 3500s, other conditions the same.

Single S4

Examples 5

Compared with Example 2, step (2) helium was changed to nitrogen; in step (2), monomer S1 was replaced with monomer S5, and step (3) monomer inlet time and discharge time were replaced with 4000s, and other conditions were the same .

Single S5

Examples 6

Compared with Example 1, the monomer S1 was replaced with S2, and other conditions were the same.

Examples 7

Compared with Example 2, the substrate is replaced with a mobile phone PCB board, and other conditions are the same.

Examples 8

Compared with Example 2, the discharge power in step (3) was changed to 5W, and other conditions were the same

Examples 9

Compared with Example 2, the monomer inflow time and discharge time in step (3) are both changed to 12000s, and other conditions are the same.

Examples 10

Compared with Example 2, the monomer flow rate in step (3) was changed to 800 μL/min, and other conditions were the same.

The substrates after the plating in the above embodiments were tested for coating thickness, water contact angle, alkali corrosion resistance, and adhesion contact resistance.

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

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

For chemical resistance, refer to GB1763-79(89) Paint Film Chemical Resistance Determination Standard for testing. Adhesion test method, according to GB/T 9286-1998 standard for 100 grid knife scratch test.

For the test method of contact resistance, refer to GB/T5095.2-1997 for testing.

Table 1

Compared with the traditional liquid phase method, the process of preparing the epoxy coating by this technical solution does not require the use of environmental pollutants such as curing agents and organic solvents, and the coating prepared by this technology can achieve alkali resistance and high viscosity in the nanometer range Attached, while the contact resistance is very low. At the connection of electronic products, the excellent conductivity of the applied coating is a key indicator; the coating prepared by the traditional method is tens of microns thick and has a large resistance, which cannot be applied to the connection of electronic products.

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.

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Claims (14)

An epoxy nano-coating, characterized in that the substrate is exposed to monomer vapor having the structure shown in formula (I), and a chemical reaction occurs on the surface of the substrate by plasma discharge to form a protective coating:

(I) wherein R ¹ , R ² and R ³ are independently selected from hydrogen, alkyl, aryl, halogen, haloalkyl or hydroxy; X is hydrogen or halogen, m is an integer of 0-8 and n is 1- An integer of 15. An epoxy nano-coating according to item 1 of the patent application range, wherein R ¹ , R ² and R ^{3 are} independently selected from hydrogen, alkyl, halogen or haloalkyl. An epoxy nano-coating according to item 2 of the patent application range, wherein the halogen is fluorine, and the halogenated alkyl group is a linear or perfluoroalkyl group having a carbon number of 1-10 . An epoxy nanocoating according to item 1 of the patent application range, wherein X is fluorine, m is 0, 1, 2 or 3, and n is an integer of 1-8. An epoxy nano-coating according to item 1 of the patent application range, wherein the substrate is metal, optical instrument, clothing fabric, electronic device or medical device. A method for preparing an epoxy nano-coating described in any one of claims 1 to 5 includes the following steps: (1) Place the substrate in the reaction chamber of the plasma chamber, and evacuate the vacuum in the reaction chamber to 0.1-1000 mTorr; (2) Inject the plasma source gas, start the plasma discharge for deposition, and vaporize the monomer into the reaction chamber for chemical vapor deposition reaction; (3) Turn off the plasma discharge for deposition, pass clean compressed air or inert gas to return to normal pressure, open the cavity, and remove the substrate. The method for preparing an epoxy nano-coating according to item 6 of the patent application range is characterized in that the monomer is introduced into the reaction chamber after being vaporized under reduced pressure. The method for preparing an epoxy nano-coating according to item 6 of the patent application range, characterized in that the plasma source gas in step (2) is one or several of helium, argon, nitrogen, and hydrogen mixture. The method for preparing an epoxy nano-coating according to item 6 of the patent application range, characterized in that the volume of the plasma chamber is 1L-2000 L, and the flow rate of the plasma source gas is 1-1000sccm The flow rate of the monomer vapor is 1-2000 μL/min. The method for preparing an epoxy nano-coating according to item 6 of the patent application range, characterized in that in the step (2), after the plasma source gas is passed in and the deposition plasma is discharged Previously, it also included a plasma discharge process for pretreatment of the substrate. The method for preparing an epoxy nano-coating according to item 10 of the patent application range is characterized in that the pretreatment plasma discharge power is 1-1000 W and the continuous discharge time is 1-6000 s. The method for preparing an epoxy nano-coating according to item 6 of the patent application range, characterized in that, in the step (2), the power of the plasma discharge for deposition is 2-500 W, and the continuous discharge time is 600-18000s . The method for preparing an epoxy nano-coating according to item 6 or item 10 of the patent application range, characterized in that the plasma discharge method is radio frequency discharge, microwave discharge, intermediate frequency discharge, penning discharge or electric spark Discharge. The method for preparing a nano-coating according to item 6 or item 10 of the patent application range is characterized in that the plasma discharge method is radio frequency discharge, and the energy output method for controlling plasma radio frequency during radio frequency discharge is pulse or Continuous output, when the plasma radio frequency energy output mode is pulse output, the pulse width is 10μs-50ms, and the repetition frequency is 20Hz-10kHz.