TWI846402B - An antifog coating, a preparation method thereof, and a product - Google Patents

Abstract

The anti-fog coating of a specific implementation mode of the present invention is formed by plasma polymerization of saturated chain monomers, wherein the saturated chain monomers have hydrophilic groups at least at both ends, and the hydrophilic groups are hydroxyl groups, amino groups or carboxyl groups; the carbon-carbon connecting bonds in the saturated chain monomers have or do not have imino groups; the saturated chain monomers have or do not have substituents, and the substituents are hydroxyl groups, amino groups or carboxyl groups; and at most one of the amino groups or hydroxyl groups is connected to the same carbon atom in the saturated chain monomers. The antifog coating formed by the plasma polymerization of the saturated chain monomer has excellent hydrophilic properties, small color difference, excellent light transmittance, and good wear resistance. At the same time, since the monomer does not contain double bonds, the adverse effects on the coating caused by unstable double bond residues in the coating during long-term use are avoided. The antifog coating of the specific implementation method of the present invention is suitable for antifog coating on the surface of transparent substrates.

Description

An anti-fog coating, a preparation method thereof, and a product thereof

The present invention relates to the field of plasma chemistry, and in particular to an antifog coating, a preparation method thereof, and a product thereof.

This invention claims priority to a Chinese patent application filed with the China Patent Office on March 29, 2022, with application number 202210319342.4, and entitled “Antifog coating, preparation method thereof, and product”, the entire contents of which are incorporated herein by reference.

Transparent materials (such as glass and plastic) are widely used in industrial and agricultural production, daily life and the military, such as goggles, laser protective glasses, telescopes and lenses of various photographic equipment, observation windows of various machines, sports diving goggles, bathroom glass, chemical or biological protective masks, vehicle windshields and rearview mirrors, explosive disposal and protection equipment, helmets, solar panels, observation windows of measuring instruments, glass covers, glass walls of greenhouses, etc. However, when we breathe out in winter, glasses will make us "see flowers in the fog"; in the cold winter, the fog on the windshield surface will greatly affect our visibility and even cause accidents. The fogging problem brings many inconveniences to people's work and life. The research and development of anti-fog technology and anti-fog materials have attracted much attention from the scientific and business communities.

Setting an anti-fog coating on the surface of transparent materials is a common anti-fog method. There are usually two types of anti-fog coatings. One is to form a hydrophilic surface on the surface of the transparent material, and water droplets spread into a film on the hydrophilic surface. The other is to form a hydrophobic surface on the surface of the transparent material, and water droplets roll down in beads on the hydrophobic surface. The disadvantage of the latter is that when a large amount of water vapor condenses rapidly, fogging will still occur. The former forms a uniform water film to eliminate the diffuse reflection of light and achieve the purpose of anti-fogging.

At present, the technical improvement of hydrophilic antifog coating is mainly focused on the traditional liquid phase treatment method, including gel-sol method, layer-by-layer self-assembly method, free radical solution polymerization method, etc. These methods generally use spraying or spin coating to apply the glue to the surface of the substrate, and then use heating or ultraviolet (UV) irradiation to cure. In the liquid phase treatment method, there is a disadvantage: the presence of solvents and reaction media may react with the substrate, destroy the substrate structure, and produce potential hazards.

Plasma Enhanced Chemical Vapor Deposition (PECVD) is a chemical vapor deposition process that uses plasma generated by glow discharge under low pressure to activate monomers, generate highly active monomer free radicals or ion fragments, and deposit them on the surface of the substrate to react and form a film. PECVD has the advantages of fast deposition rate, good film quality, fewer pinholes, and not easy to crack. No liquid solvent is required during the reaction process, and it will not damage the substrate. Therefore, the use of PECVD technology provides a better choice for the preparation of hydrophilic antifogging coatings. The inventors have found in previous studies, such as the invention in CN111501023A, that by using acrylic monomers and PECVD to prepare hydrophilic coatings, a hydrophilic antifogging coating can be prepared. On the one hand, the hydrophilic properties of the coating need to be improved; on the other hand, the monomers of the coating contain double bonds, and unstable double bond residues will inevitably remain after the reaction, which may affect the performance of the coating during long-term use.

The implementation method of the present invention provides an antifog coating, which has no residual double bonds and has excellent hydrophilic properties, light transmittance, and good wear resistance. The specific scheme is as follows:

An antifog coating, the antifog coating being formed by a substrate contacting a plasma containing a monomer of formula (1);

_X2 - _RX1 (1)

In formula (1), R is a C ₁ -C ₃₀ alkylene group or a C ₁ -C ₃₀ substituted alkylene group, X ₁ and X ₂ are independently selected from a hydroxyl group, an amino group or a carboxyl group; the substituent of the substituted alkylene group is a hydroxyl group, an amino group or a carboxyl group; the C ₁ -C ₃₀ alkylene group or the C ₁ -C ₃₀ substituted alkylene group has or does not have -NH- between the carbon-carbon connecting bonds; and in formula (1), at most one of the amino group or the hydroxyl group is connected to the same carbon atom.

Optionally, the monomer of formula (1) has the structure shown in formula (2),

In formula (2), _R1 and _R2 are independently selected from _C1 - _C10 alkylene groups or _C1 - _C10 substituted alkylene groups.

Optionally, the monomer of formula (1) has the structure shown in formula (3),

In formula (3), _X3 and _X4 are independently selected from hydrogen atom, methyl, hydroxyl, hydroxymethyl, amino or carboxyl; _n1 is 0, 1, 2, 3, 4, 5, 6, 7 or 8; _n2 is 0, 1, 2, 3, 4, 5, 6, 7 or 8.

Optionally, _X3 and _X4 are both hydrogen atoms, and _X1 and _X2 are the same group.

Optionally, R is a C ₁ -C ₁₆ alkylene group or a substituted alkylene group.

Optionally, the monomer of formula (1) has the structure shown in formula (4),

In formula (4), _X5 and _X6 are independently selected from hydrogen atom, methyl, hydroxyl, hydroxymethyl, amino or carboxyl; _n3 is 0, 1, 2, 3, 4, 5, 6, 7 or 8.

Optionally, _X5 and _X6 are both hydrogen atoms, and _X1 and _X2 are the same group.

Optionally, the monomer of formula (1) is selected from monomers of structures shown in formula (1-1) to formula (1-48),

Optionally, the substrate is an optical instrument, metal, ceramic, plastic, glass or electronic equipment.

Optionally, the optical instrument is a lens, a reflector or a lens.

Optionally, the substrate is a transparent material.

Optionally, the light transmittance of the anti-fog coating is above 90%.

Optionally, the water contact angle measured by the anti-fog coating is below 10°.

Optionally, after the anti-fog coating is rubbed 500 times with a dust-free cloth under a load of 1N, the measured water contact angle is below 10°.

The specific implementation of the present invention also provides a method for preparing an antifog coating, which is used to prepare the antifog coating described above. The method for preparing the antifog coating comprises the following steps: providing a substrate, placing the substrate in a plasma reactor, passing the monomer vapor of the formula (1) into the plasma reactor, discharging the plasma, and polymerizing the plasma on the surface of the substrate to form the antifog coating.

Optionally, before the monomer vapor of formula (1) is introduced into the plasma reactor, a plasma source gas is introduced first, and the plasma device is turned on for continuous discharge to pre-treat the substrate surface.

Optionally, the plasma source gas is one or a mixture of helium, argon, nitrogen, oxygen, and hydrogen.

Optionally, the plasma discharge is a pulse plasma discharge, wherein the pulse power is 10W~300W, the pulse duty cycle is 20%~90%, and the discharge time of the pulse output is 30s~36000s.

Optionally, the monomer of formula (1) is first added to an alcohol solvent to prepare a solution, which is then vaporized and introduced into a plasma reactor.

Optionally, the alcohol is one or more of methanol, ethanol or propanol.

A product, at least part of the surface of which has the anti-fog coating described above.

Compared with the existing technology, the technical solution of the embodiment of the present invention has the following beneficial effects:

The antifog coating of a specific embodiment of the present invention is formed by plasma polymerization of a saturated chain monomer having at least hydroxyl, amino or carboxyl groups at both ends as shown in the substrate contact formula (1). The antifog coating formed by plasma polymerization of the monomer with the structure has excellent hydrophilic properties, small color difference, excellent light transmittance and good wear resistance. At the same time, since the monomer does not contain double bonds, the adverse effects on the performance of the antifog coating during long-term use caused by unstable double bond residues in the antifog coating are avoided. The antifog coating of the specific implementation method of the present invention is particularly suitable for use as a hydrophilic antifog coating on the surface of a transparent substrate.

The inventors have found that the antifog coating formed by plasma polymerization of the saturated chain monomer shown in formula (1) has excellent hydrophilicity, light transmittance and good wear resistance. At the same time, since the monomer does not contain double bonds, the adverse effects on the performance of the antifog coating during long-term use caused by the residual unstable double bonds in the antifog coating are avoided. The antifog coating of the specific implementation method of the present invention is particularly suitable for use as a hydrophilic antifog coating on the surface of a transparent substrate.

The present invention provides an antifog coating of the following specific implementation method, wherein the antifog coating is a plasma polymerization coating formed by contacting a substrate with a plasma containing a monomer of formula (1),

_X2 - _RX1 (1)

In formula (1), R is a C ₁ -C ₃₀ alkylene or substituted alkylene, X ₁ and X ₂ are independently selected from hydroxyl, amino or carboxyl; the substituent of the substituted alkylene is hydroxyl, amino or carboxyl; the C ₁ -C ₃₀ alkylene or substituted alkylene has or does not have -NH- between carbon-carbon bonds; and in formula (1), at most one of amino or hydroxyl is connected to the same carbon atom.

In the antifog coating of a specific embodiment of the present invention, _X1 and _X2 are independent of each other, and _X1 and _X2 can be the same group, for example, _X1 and _X2 are both hydroxyl, carboxyl or amino; _X1 and _X2 can also be different groups, for example, _X1 is a hydroxyl group and _X2 is a carboxyl group, for example, _X1 is a hydroxyl group and _X2 is an amino group.

In the antifog coating of the specific embodiment of the present invention, at most one of an amino group or a hydroxyl group is connected to the same carbon atom, which means: the same carbon atom is only connected to one hydroxyl group, the same carbon atom is only connected to one amino group, or the same carbon atom has neither a hydroxyl group nor an amino group.

In the antifog coating of a specific embodiment of the present invention, the C ₁ -C ₃₀ alkylene group or C ₁ -C ₃₀ substituted alkylene group may be a linear or branched alkylene group. However, in consideration of better wear resistance and hydrophilicity, in some specific embodiments, the C ₁ -C ₃₀ alkylene group or C ₁ -C ₃₀ substituted alkylene group is a linear C ₁ -C ₃₀ alkylene group or substituted alkylene group.

In some specific examples of the antifog coating of the specific embodiment of the present invention, the carbon-carbon connecting bond of the C ₁ -C ₃₀ alkylene or substituted alkylene has -NH-.

In the antifog coating of the specific implementation mode of the present invention, in some specific embodiments, the monomer of formula (1) has the structure shown in formula (2),

In formula (2), _R1 and _R2 are independently selected from _C1 - _C10 alkylene or substituted alkylene groups.

In the antifog coating of the specific implementation mode of the present invention, in some specific embodiments, the monomer of formula (1) has the structure shown in formula (3),

In formula (3), _X3 and _X4 are independently selected from hydrogen atom, methyl, hydroxyl, hydroxymethyl, amino or carboxyl; _n1 is 0, 1, 2, 3, 4, 5, 6, 7 or 8; _n2 is 0, 1, 2, 3, 4, 5, 6, 7 or 8.

The antifog coating of the specific implementation mode of the present invention takes into account better hydrophilic properties. In some specific embodiments, in formula (3), _n1 is 0, 1 or 2, and _n2 is 0, 1 or 2.

In the antifog coating of the specific embodiment of the present invention, taking into account better hydrophilic properties, in some specific embodiments, in formula (3), _X3 and _X4 are both hydrogen atoms, and _X1 and _X2 are both hydroxyl groups, amino groups, or carboxyl groups.

In the antifogging coating of the specific embodiment of the present invention, taking into account better hydrophilic properties, in some specific embodiments, in formula (1), R is a C ₁ -C ₁₆ alkylene group or a substituted alkylene group.

In some specific examples of the antifog coating of the specific embodiment of the present invention, there is no -NH- between the carbon-carbon bonds of the C ₁ -C ₃₀ alkylene or substituted alkylene.

In the antifog coating of the specific implementation mode of the present invention, in some specific embodiments, the monomer of formula (1) has the structure shown in formula (4),

In formula (4), _X5 and _X6 are independently selected from hydrogen atom, methyl, hydroxyl, hydroxymethyl, amino or carboxyl; _n3 is 0, 1, 2, 3, 4, 5, 6, 7 or 8.

In the antifog coating of the specific implementation mode of the present invention, taking into account better hydrophilic properties, in some specific embodiments, in formula (4), n ₃ is 0, 1, 2, 3 or 4.

In the antifog coating of the specific embodiment of the present invention, taking into account better hydrophilic properties, in some specific embodiments, in formula (4), _X5 and _X6 are both hydrogen atoms, and _X1 and _X2 are both hydroxyl groups, amino groups, or carboxyl groups.

In the antifog coating of the specific implementation mode of the present invention, in some specific embodiments, the monomer of formula (1) is selected from monomers of structures shown in formula (1-1) to formula (1-48),

In the antifog coating of the specific implementation mode of the present invention, in some specific embodiments, the substituent of the substituted alkylene group is a hydroxyl group, an amino group or a carboxyl group.

In the anti-fog coating of the specific implementation mode of the present invention, in some specific embodiments, the substrate is an optical instrument, metal, ceramic, plastic, glass or electronic equipment, etc.

The antifog coating of the specific implementation of the present invention, in some specific implementation examples, the water contact angle of the antifog coating is measured to be below 10° according to GB/T 30447-2013, and water droplets can spread on the surface of the antifog coating and form a relatively uniform water film, thereby reducing the diffuse reflection of light to play an antifog function. Therefore, in some specific implementation examples, the antifog coating is particularly suitable for being an antifog coating of a transparent material. For example, in some specific implementation examples, In the formula, the substrate is a lens of glasses, goggles, laser protective glasses, telescopes and lenses of various photographic equipment, observation windows of various machines, sports diving goggles, bathroom glass, chemical or biological protective masks, vehicle windshields and rearview mirrors, explosive disposal and protective equipment, helmets, solar panels, observation windows of measuring instruments, glass covers, glass walls of greenhouses, etc.

The antifog coating of the specific implementation of the present invention, in some specific implementations, has excellent wear resistance and hydrophilicity. After the antifog coating is rubbed 500 times with a dust-free cloth at a load of 1N, the water contact angle measured according to GB/T 30447-2013 is below 10°.

In some specific implementations of the antifog coating of the present invention, the light transmittance of the antifog coating is above 90%, which will not cause excessive impact on the light transmittance of the transparent substrate.

The antifog coating of the specific implementation of the present invention, in some specific implementations, is a plasma polymerization coating formed by the plasma of the monomer of the structure shown in formula (1), and in other specific implementations, due to specific practical needs, the antifog coating is a plasma polymerization coating formed by the plasma of the monomer of the structure shown in formula (1) and other monomers.

In some specific embodiments of the antifog coating of the present invention, the thickness of the antifog coating is 1 to 1000 nm. In some specific embodiments, as an ultra-thin transparent nano coating, the thickness of the antifog coating is 1 to 100 nm, specifically, for example, 49 nm, 54 nm, 56 nm, 61 nm, 73 nm, 79 nm, 82 nm, 87 nm, 92 nm, 93 nm, 96 nm or 98 nm.

The specific implementation of the present invention also provides a method for preparing the above-mentioned antifogging coating, comprising the following steps: providing a substrate, placing the substrate in a plasma reactor, passing the monomer vapor of the formula (1) into the plasma reactor, discharging the plasma, and polymerizing the plasma on the surface of the substrate to form the antifogging coating.

The preparation method of the antifog coating of the specific implementation mode of the present invention is as described above for the monomer and substrate.

The preparation method of the antifog coating of the specific implementation of the present invention is to further enhance the bonding strength between the plasma coating and the substrate. In some specific implementations, before the monomer vapor is introduced, the substrate is pre-treated by using a continuous plasma source gas. The specific pre-treatment method is, for example, in the atmosphere of the plasma source gas, using a plasma discharge power of 20~500W, a continuous discharge method, and a continuous discharge time of 10s~3600s.

In the method for preparing the antifog coating of the specific implementation of the present invention, in some specific implementations, monomer vapor is introduced at the same time as the plasma source gas to perform pretreatment and pre-deposition of the coating.

In the method for preparing the antifog coating of the specific implementation of the present invention, in some specific implementations, the plasma source gas introduced is one or a mixture of several of helium, argon, nitrogen, oxygen and hydrogen.

In the specific implementation of the present invention, the preparation method of the anti-fog coating, in some specific implementations, the plasma of the monomer is a plasma excited in a pulsed manner, and the monomer flow rate is 10~500μL/min, for example, it can be 10μL/min, 50μL/min, 100μL/min, 150μL/min, 200μL/min, 300μL/min or 400μL/min, etc.

In the method for preparing the antifog coating of the specific implementation of the present invention, in some specific implementations, the temperature in the cavity is controlled at 20℃~80℃, for example, it can be 20℃, 25℃, 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, 70℃, 75℃ or 80℃, etc.; the pressure in the cavity is below 1000 mTorr, further below 500 mTorr, and further below 100 mTorr.

In the preparation method of the antifog coating of the specific implementation of the present invention, in some specific implementations, the monomer vaporization temperature is 50°C~200°C, and specifically can be 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, etc., and vaporization occurs under vacuum conditions, and the pulsed plasma is generated by applying a pulse voltage discharge, wherein the pulse The pulse power is 10W~300W, and specifically can be 10W, 20W, 30W, 40W, 50W, 70W, 80W, 100W, 120W, 140W, 160W, 180W, 190W, 200W, 210W, 220W, 230W, 240W, 250W, 260W, 270W, 280W, 290W or 300W, etc. In some specific implementations, the pulse power is 30W~100W; the pulse duty cycle is 0.1% ~90%, specifically for example, it can be 0.1%, 0.5%, 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85% or 90%, etc. In some specific embodiments, considering better hydrophilicity, the pulse duty cycle is 20%~90%, further the pulse duty cycle is 40%~80%, further the pulse duty cycle is 45%~75%; The plasma discharge time of the pulse output is 30s~36000s, and specifically can be 100s, 500s, 1000s, 1800s, 2000s, 1000s, 2000s, 3000s, 3600s, 4000s, 5000s, 6000s, 7000s, 7200s, 10800s, 14400s, 18000s, 21600s, 25200s, 28800s, 32400s or 36000s, etc.

In the preparation method of the anti-fog coating of the specific embodiment of the present invention, in some specific embodiments, the plasma discharge method can be various existing discharge methods, for example, electrodeless discharge (such as radio frequency inductively coupled discharge, microwave discharge), single electrode discharge (such as coma discharge, plasma jet formed by single electrode discharge), double electrode discharge (such as dielectric barrier discharge, bare electrode radio frequency glow discharge) and multi-electrode discharge (such as discharge using a floating electrode as the third electrode).

In the preparation method of the antifog coating of the specific implementation of the present invention, in some specific implementations, the monomer of formula (1) is first added to an alcohol solvent to prepare a solution, and then vaporized and enters a plasma reactor. This method can reduce the vaporization temperature of the monomer, which is more conducive to the vaporization of the monomer. In some specific implementations, the alcohol is one or more of methanol, ethanol or propanol.

The specific implementation of the present invention also provides a product, at least part of the surface of the product has any of the above-mentioned anti-fog coatings. In some specific implementations, the above-mentioned anti-fog coating is deposited on part or all of the surface of the device.

The present invention is further described below through specific embodiments.

Implementation example

Test method description

Coating thickness test: Use the American Filmetrics F20-UV-film thickness meter for testing.

Coating water contact angle: tested according to GB/T 30447-2013 standard.

；T表示透光率；L、a、b表示Lab色彩模型中的三個顏色通道，L表示亮度，取值範圍是[0，100]，表示從純黑到純白；a表示從紅色到綠色的範圍，取值範圍是[127，-128]；b表示從黃色到藍色的範圍，取值範圍是[127，-128]。 Coating transmittance and color difference: calculated according to GB11186.3-1989 standard, tested using a spectrophotometer. △E in the test results represents color difference.

; T represents transmittance; L, a, and b represent the three color channels in the Lab color model. L represents brightness, and its value range is [0, 100], representing from pure black to pure white; a represents the range from red to green, and its value range is [127, -128]; b represents the range from yellow to blue, and its value range is [127, -128].

Friction performance test: Use a reciprocating abrasion machine to rub 500 times with a dust-free cloth under a load of 1N, and test the change in water contact angle before and after friction.

Implementation Example 1

Place a substrate transparent glass plate (length: 75mm, width: 26mm, thickness 1mm) in a 500L plasma vacuum reaction chamber, continuously evacuate the reaction chamber to a vacuum degree of 80 mTorr, the temperature inside the chamber is 45°C, and helium is introduced at a flow rate of 40sccm;

Maintain the chamber pressure at 80 mTorr, maintain the helium flow rate at 40 sccm, turn on the RF plasma discharge, the RF energy output mode is continuous discharge, the discharge time is 30s, and the discharge power is 300w.

Then, a monomer with the structure shown in formula (1-6) is introduced, the monomer flow rate is 50μL/min, the monomer vaporization temperature is 90℃, the chamber pressure is maintained at 80 mTorr, the helium flow rate is maintained at 40sccm, the RF plasma discharge is turned on, the RF energy output mode is pulse, the discharge power is 40w, the pulse duty cycle is 75%, the pulse frequency is 50Hz, the discharge time is 3600s, and a coating is formed on the surface of the transparent glass plate;

After the coating preparation is completed, air is introduced to restore the reaction chamber to normal pressure, the chamber is opened, and the transparent glass plate is taken out to test the coating thickness, light transmittance, chromaticity, water contact angle and friction resistance. The test results are listed in Table 1 below.

Example 2

The monomer of the structure shown in formula (1-6) in Example 1 is replaced by the monomer of the structure shown in formula (1-4) below. The vaporization temperature of the monomer of the structure shown in formula (1-4) is 90°C. The other processes are consistent with Example 1. The prepared coating is tested for thickness, light transmittance, chromaticity, water contact angle and friction resistance. The test results are listed in Table 1 below.

Example 3

The monomer of the structure shown in formula (1-6) in Example 1 is replaced with the monomer of the structure shown in formula (1-19) below. The vaporization temperature of the monomer of the structure shown in formula (1-19) is 110°C. The other processes are consistent with Example 1. The prepared coating is tested for thickness, light transmittance, chromaticity, water contact angle and friction resistance. The test results are listed in Table 1 below.

Example 4

The transparent glass substrate in Example 1 was replaced with a transparent polycarbonate (PC) substrate. The other processes were the same as in Example 1. The prepared coating was tested for thickness, light transmittance, chromaticity, water contact angle and friction resistance. The test results are listed in Table 1 below.

Example 5

The transparent glass substrate in Example 2 was replaced with a transparent PC substrate. The other processes were the same as in Example 2. The prepared coating was tested for thickness, light transmittance, chromaticity, water contact angle and friction resistance. The test results are listed in Table 1 below.

Example 6

The transparent glass substrate in Example 3 was replaced with a transparent PC substrate. The other processes were the same as in Example 3. The prepared coating was tested for thickness, light transmittance, chromaticity, water contact angle and friction resistance. The test results are listed in Table 1 below.

Example 7

Place a substrate transparent glass plate (length: 75mm, width: 26mm, thickness 1mm) in a 500L plasma vacuum reaction chamber, continuously evacuate the reaction chamber to a vacuum degree of 80 mTorr, the temperature inside the chamber is 45°C, and helium is introduced at a flow rate of 40sccm;

Maintain the chamber pressure at 80 mTorr, maintain the helium flow rate at 40 sccm, turn on the RF plasma discharge, the RF energy output mode is continuous discharge, the discharge time is 30s, and the discharge power is 300w;

Then, 20g of the monomer of the structure shown in the following formula (1-43) and 100mL of ethanol were prepared into a solution, and the solution was vaporized at 150°C and then introduced into the reaction chamber at a flow rate of 150μL/min, the chamber pressure was maintained at 80 mTorr, the helium flow rate was maintained at 160sccm, and the radio frequency plasma discharge was turned on. The radio frequency energy output mode was pulse, the discharge power was 40w, the pulse frequency was 50Hz, the pulse duty cycle was 45%, and the discharge time was 3600s, and a coating was formed on the surface of the transparent glass plate;

After the coating preparation is completed, air is introduced to restore the reaction chamber to normal pressure, the chamber is opened, and the transparent glass plate is taken out to test the coating thickness, light transmittance, chromaticity, water contact angle and friction resistance. The test results are listed in Table 1.

Example 8

The monomer of the structure shown in formula (1-43) in Example 7 is replaced by the monomer of the structure shown in formula (1-21) below. The other processes are consistent with Example 7. The prepared coating is tested for thickness, light transmittance, chromaticity, water contact angle and friction resistance. The test results are listed in Table 1 below.

Example 9

The transparent glass substrate in Example 7 was replaced with a transparent PC substrate. The other processes were the same as those in Example 7. The prepared coating was tested for thickness, light transmittance, chromaticity, water contact angle and friction resistance. The test results are listed in Table 1 below.

Example 10

The transparent glass substrate in Example 8 was replaced with a transparent PC substrate. The other processes were the same as in Example 8. The prepared coating was tested for thickness, light transmittance, chromaticity, water contact angle and friction resistance. The test results are listed in Table 1 below.

Comparative Example 1

The monomer of the structure shown in formula (1-6) in Example 1 is replaced with the hexanol monomer of the structure shown in formula (5) below. The vaporization temperature of the hexanol monomer of the structure shown in formula (5) is 110°C. The other processes are consistent with Example 1. The prepared coating is tested for thickness, light transmittance, chromaticity, water contact angle and friction resistance. The test results are listed in Table 1.

Comparative Example 2

The monomer of the structure shown in formula (1-6) in Example 4 is replaced by the caproic acid monomer of the structure shown in formula (6). The vaporization temperature of the caproic acid monomer of the structure shown in formula (6) is 110°C. The other processes are consistent with Example 5. The prepared coating is tested for thickness, light transmittance, chromaticity, water contact angle and friction resistance. The test results are listed in Table 1.

Table 1 Performance test results of Examples 1-10 and Comparative Examples 1-2

According to the results in Table 1, the coatings of Examples 1 to 10 before friction all have a water contact angle of 5° to 6°, which is much lower than the water contact angles of 77° and 72° of the coatings of Comparative Examples 1 and 2, which further shows that compared with the monomers of Comparative Examples 1 and 2 having one hydrophilic group, the coatings formed by plasma polymerization of monomers having two hydrophilic groups in Examples 1 to 10 have better hydrophilic properties and anti-fogging properties.

At the same time, according to the results in Table 1, the coatings formed by plasma polymerization of saturated chain monomers with hydroxyl, amino or carboxyl groups at both ends of Examples 1 to 10 have good wear resistance. After rubbing 500 times with a dust-free cloth under a load of 1N using a reciprocating abrasion machine, the change in water contact angle does not exceed 4°, and the color difference of the coating is very small, between 0.5 and 0.6, and the light transmittance of the coating is very good. Compared with Comparative Example 1, Comparative Example 2 and the transparent glass plate and PC plate without deposition of the coating, it has a higher light transmittance and has a certain degree of anti-reflection effect.

In addition, it can be seen from Examples 7 to 10 that for monomers with higher boiling points, the boiling point of the monomers can be lowered by adding ethanol, and the final coating also has excellent hydrophilicity and wear resistance, small color difference, and excellent light transmittance.

Although the present invention is disclosed as above, it is not limited thereto. Any person skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope defined in the claims.

Claims (20)

An antifog coating, characterized in that the antifog coating is formed by contacting a substrate with a plasma containing a monomer of formula (1); _X2 - _RX1 (1) In formula (1), R is a _C1 - _C30 alkylene group or a _C1 - _C30 substituted alkylene group, _X1 is selected from a hydroxyl group, an amino group or a carboxyl group, and _X2 is selected from a hydroxyl group or a carboxyl group; the substituent of the substituted alkylene group is a hydroxyl group or a carboxyl group; the _C1 - _C30 alkylene group or the _C1 - _C30 substituted alkylene group has or does not have -NH- between carbon-bonds; and in formula (1), at most one of the amino group or the hydroxyl group is connected to the same carbon atom; the water contact angle of the antifog coating is less than 10°. The antifog coating according to claim 1, wherein the monomer of formula (1) has a structure represented by formula (2),

In formula (2), _R1 and _R2 are independently selected from _C1 - _C10 alkylene groups or _C1 - _C10 substituted alkylene groups. The antifog coating according to claim 2, wherein the monomer of formula (1) has a structure represented by formula (3),

In formula (3), _X3 and _X4 are independently selected from hydrogen atom, methyl, hydroxyl, hydroxymethyl or carboxyl; _n1 is 0, 1, 2, 3, 4, 5, 6, 7 or 8; _n2 is 0, 1, 2, 3, 4, 5, 6, 7 or 8. The antifog coating as described in claim 3, wherein _X3 and _X4 are both hydrogen atoms, and _X1 and _X2 are the same group. The antifog coating according to claim 1, wherein R is a C ₁ -C ₁₆ alkylene group or a substituted alkylene group. The antifog coating according to claim 5, wherein the monomer of formula (1) has a structure represented by formula (4),

In formula (4), _X5 and _X6 are independently selected from hydrogen atom, methyl, hydroxyl, hydroxymethyl or carboxyl; _n3 is 0, 1, 2, 3, 4, 5, 6, 7 or 8. The antifog coating as described in claim 6, wherein _X5 and _X6 are both hydrogen atoms, and _X1 and _X2 are the same group. The antifog coating as claimed in claim 1, wherein the monomer of formula (1) is selected from monomers having the structure shown in the following structural formula:

The anti-fog coating as described in claim 1, wherein the substrate is an optical instrument, metal, ceramic, plastic, glass or electronic equipment. The anti-fog coating as described in claim 9, wherein the optical instrument is a lens, a reflector or a lens. The anti-fog coating as described in claim 9, wherein the substrate is a transparent material. The anti-fog coating as described in claim 1, wherein the light transmittance of the anti-fog coating is above 90%. The anti-fog coating as described in claim 1, wherein the water contact angle measured after the anti-fog coating is rubbed 500 times with a dust-free cloth under a load of 1N is less than 10°. A method for preparing an antifog coating as described in any one of claims 1 to 13, comprising the following steps: providing a substrate, placing the substrate in a plasma reactor, passing the monomer vapor of formula (1) into the plasma reactor, discharging the plasma, and polymerizing the plasma on the surface of the substrate to form the antifog coating. The method for preparing the anti-fog coating as described in claim 14, wherein before the monomer vapor of formula (1) is introduced into the plasma reactor, the plasma source gas is first introduced, and the plasma device is turned on for continuous discharge to pre-treat the surface of the substrate. The method for preparing an anti-fog coating as described in claim 15, wherein the plasma source gas is one or a mixture of several of helium, argon, nitrogen, oxygen, and hydrogen. The method for preparing an anti-fog coating as described in claim 14, wherein the plasma discharge is a pulsed plasma discharge, wherein the pulse power is 10W~300W, the pulse duty cycle is 20%~90%, and the discharge time of the pulse output is 30s~36000s. The method for preparing the antifog coating as described in claim 14, wherein the monomer of formula (1) is first added to an alcohol solvent to prepare a solution, which is then vaporized and introduced into a plasma reactor. The method for preparing an antifog coating as described in claim 18, wherein the alcohol is one or more of methanol, ethanol or propanol. A product with an antifog coating, characterized in that at least part of the surface of the product has the antifog coating described in any one of claims 1 to 13.