A scratch-resistant, stain-resistant, anti-reflective, anti-reflective coating and a preparation method thereof

Abstract

The present invention relates to a scratch-resistant, stain-resistant, anti-reflective, and anti-reflective coating and its preparation method. The scratch-resistant, stain-resistant, and anti-reflective coating is made from the following materials: 50-77% epoxy oligomer; 20-40% spherical hollow nano-silica; 1-5% nano-inorganic oxide; 1-5% fluorine / silicon compound; and 1-5% cationic photoinitiator. The preparation method comprises the following steps: adding the epoxy oligomer according to the required weight ratio to a mixer barrel and stirring; adding the required amount of nano-inorganic oxide while stirring; after the addition is complete, increasing the stirring speed of the mixer to 500-2000 rpm and stirring for 0.5-1 hour; placing the stirred slurry in a sand mill and grinding it; transferring it to a mixing barrel and adding the required amount of spherical hollow nano-silica while stirring; after stirring is complete, adding the fluorine / silicon compound and cationic photoinitiator in sequence and continuing stirring for 10-30 minutes; filtering and packaging the resulting coating, which is the scratch-resistant, stain-resistant, and anti-reflective coating.

Description

Technical Field

[0001] The present invention relates to the technical field of optical coatings, and in particular to an anti-reflection and anti-reflection coating and a preparation method thereof. Background Art

[0002] With the development of optoelectronic and electronic technologies, the application of electronic and optoelectronic products is becoming increasingly widespread. As an extension of display screen enhancement and protection, coatings are widely used in mobile phones, tablet computers, and automotive display cover panels. Therefore, they are also required to have strong hardness, scratch resistance, and stain resistance while ensuring transmittance. Solar cell covers are exposed to the outdoors for a long time and are contaminated by dust, bird droppings, and other pollutants, which reduces the photovoltaic conversion efficiency of solar cells. Developing a coating that can increase light transmittance while also having high hardness, scratch resistance, and excellent stain resistance clearly has broad application prospects.

[0003] Currently, domestically produced antireflective and antireflective coatings have poor scratch resistance. Some with good steel wool resistance only last about 100 times at a 500g load, while others typically last less than 20 times. Mobile phone display cover panels require less than five scratches after 1000 times at a 1000g load. Existing technology is far from meeting this requirement. Currently, mass production of these products is largely dominated by Japanese companies. Summary of the Invention

[0004] The present invention addresses the shortcomings of existing technologies and proposes a scratch-resistant, stain-resistant, anti-reflective, and anti-reflective coating. The coating has high hardness, scratch resistance, and stain resistance, while also improving the light transmittance of display screens or solar cell glass cover plates.

[0005] The technical solution adopted in the present invention is:

[0006] A scratch-resistant, stain-resistant, anti-reflective, and anti-reflective coating, comprising the following materials in percentage by weight:

[0007] Epoxy oligomer 50~77%

[0008] Spherical hollow nano-silica 20-40%

[0009] Nano inorganic oxides 1-5%

[0010] Fluorine / silicon compounds 1~5%

[0011] Cationic photoinitiator 1-5%.

[0012] The epoxy oligomers include one or more of epoxy acrylate oligomers, epoxy glycidyl ether oligomers, epoxy cyclohexane oligomers, and multifunctional alicyclic epoxy oligomers. Trifunctional or higher epoxy glycidyl ether oligomers and / or epoxy cyclohexane oligomers are preferred for their improved scratch resistance. More preferably, pentafunctional or higher oligomers exhibit superior hardness and scratch resistance.

[0013] Epoxy group-containing oligomers such as epoxy glycidyl ether and epoxy cyclohexane are selected. These oligomers can undergo cationic polymerization. Compared with free radical photopolymerization, cationic photopolymerization does not have oxygen inhibition. No nitrogen is required during the nanometer-level thickness curing process, and the equipment is simpler and the cost is lower.

[0014] The nano-inorganic oxide is one or more of solid silica, alumina, zirconium oxide, boron carbide, and silicon carbide; the particle size of the nano-inorganic oxide is between 50 and 300 nm. Considering the influence of refractive index, the nano-inorganic oxide is solid silica or alumina. Spherical or elliptical nano-inorganic oxides are selected for their excellent scratch resistance. The particle size of the nano-inorganic oxide is selected between 80 and 200 nm. The particle size of the nano-inorganic oxide must be 10 to 100 nm larger than the coating thickness.

[0015] The nano-inorganic oxide comprises 1-5% by weight of the total solids. When the nano-inorganic oxide accounts for more than 5%, the coating's refractive index increases, reducing its anti-reflective effect. When the nano-inorganic oxide accounts for less than 1%, the nano-inorganic oxide fails to provide scratch resistance. The nano-inorganic oxide includes one or more of solid silica, alumina, zirconium oxide, boron carbide, and silicon carbide. Considering the impact of refractive index, silica or alumina are preferred.

[0016] From the perspective of material particle size, it is preferred to use nano-inorganic oxides with a particle size between 50 and 300 nm. The particle size of the nano-inorganic oxide needs to be 10 to 100 nm larger than the coating thickness. It is more preferred to use nano-inorganic oxides with a particle size between 80 and 200 nm, as the scratch resistance is better at this time.

[0017] From the perspective of shape and structure, spherical or elliptical nano-inorganic oxides are preferably selected, as they have better scratch resistance.

[0018] The fluorine / silicon compound can be one or more of epoxy fluorosilicone oil, epoxy siloxane, fluorinated epoxy resin, epoxy silicone oil, and fluorinated epoxy, and the fluorine / silicon compound must contain an epoxy group. The fluorine / silicon compound flattens and smooths the surface of the coating, further improving the coating's scratch resistance.

[0019] Fluorine / silicon compounds account for 1-5% of the total solid weight ratio. When the proportion of fluorine / silicon compounds is lower than 1%, the scratch resistance will be reduced. When it is higher than 5%, the compatibility of the coating will deteriorate and the transparency will be affected. In addition, this type of additive is generally expensive, and too high a proportion will significantly increase the cost.

[0020] At the same time, due to its high water drop angle performance, the fluorine / silicon compound makes the coating have excellent stain resistance. When used in display cover plates, it can prevent the screen from being affected by hand sweat and other stains, and even if there is dirt, it is easy to remove.

[0021] The particle size of the spherical hollow nano-silica is between 20 and 200 nm, preferably between 40 and 80 nm, as this provides the best anti-reflection, anti-reflection, scratch resistance, and transparency. When the particle size is less than 40 nm, the scratch resistance of the coating decreases; when the particle size is greater than 80 nm, the transparency may decrease.

[0022] The spherical hollow nano-silica accounts for between 20% and 40% of the total solids by weight. When the proportion of the spherical hollow nano-silica exceeds 50%, the hollow silica cannot be encapsulated by the prepolymer, resulting in insufficient scratch resistance and reduced transparency of the coating. When the proportion of the hollow silica is less than 30%, the refractive index of the coating does not decrease significantly, and the anti-reflection effect is reduced.

[0023] The refractive index of the coating can be adjusted by changing the proportion of hollow silica. To obtain excellent anti-reflection effect, the refractive index of the coating should be controlled between 1.25 and 1.45.

[0024] The anti-scratch, anti-fouling, anti-reflective and anti-reflective coating is prepared by using as a cationic photoinitiator one or more of 4-isobutylphenyl-4'-methylphenyliodonium hexafluorophosphate (250), diphenyl-(4-phenylthio)phenylsulfonium hexafluoroantimonate (6976) and diphenyl-(4-phenylthio)phenylsulfonium hexafluorophosphate (6992).

[0025] The amount of cationic photoinitiator used is 1-5% by weight of the total solids, preferably 2-3% by weight of the total solids. A low initiator ratio results in incomplete curing of the coating, impairing the coating's hardness, scratch resistance, and stain resistance. A high initiator ratio results in excessive cross-linking of the coating, leading to decreased adhesion and yellowing.

[0026] It is preferred to use two or more cationic initiators, which can absorb ultraviolet light of different wavelengths and have higher initiation efficiency.

[0027] A method for preparing a scratch-resistant, stain-resistant, anti-reflective, and anti-reflective coating comprises the following steps:

[0028] S1. Add the epoxy oligomer into the mixer bucket according to the required weight ratio, start stirring, and set the speed to 300-800 rpm;

[0029] S2. Add the required amount of nano-inorganic oxide while stirring;

[0030] S3. After the addition is completed, increase the stirring speed of the stirrer to 500-2000 rpm and stir for 0.5-1 hour;

[0031] S4, placing the stirred slurry into a sand mill for grinding until the nano-inorganic oxide is ground to the original nano-particle size;

[0032] S5. The ground slurry is transferred to a mixing barrel, and stirring is started, with the speed set at 300-800 rpm.

[0033] S6. Add the required amount of spherical hollow nano-silica while stirring, set the speed to 500-2000 rpm, and stir for 1-2 hours;

[0034] S7. After stirring, add fluorine / silicon compound and cationic photoinitiator in sequence, and continue stirring at a speed of 300-800 rpm for 10-30 minutes;

[0035] S8, filtering and packaging, the obtained coating is a scratch-resistant, stain-resistant, anti-reflective and anti-reflective coating.

[0036] The anti-scratch, anti-fouling, anti-reflection and anti-reflection coating is applied to glass cover plates and solar cell glass plates.

[0037] The anti-scratch, anti-fouling, anti-reflection and anti-reflection coating is applied to a transparent plastic substrate.

[0038] Beneficial effects of the invention:

[0039] 1. This invention uses low-refractive-index spherical hollow nano-silica as a filler, imparting a low reflectivity to the coating while also improving its scratch resistance. This coating is used in mobile phones, tablet computers, and automotive display cover panels. By reducing the reflectivity of the cover panel surface, it increases the transmittance of the display screen, enhancing the user's visual experience in sunlight. It can also be used in solar panels to increase the transmittance of sunlight, thereby improving solar energy utilization.

[0040] 2. The present invention uses nano-inorganic oxides to further improve the scratch resistance of the coating.

[0041] 3. The present invention uses fluorine / silicon compounds to give the coating a higher water drop angle and oil drop angle, with hydrophobic and oleophobic properties, thereby obtaining excellent anti-fouling ability and better smoothness.

[0042] 4. The present invention uses epoxy oligomers to have a good encapsulation effect on inorganic nanopowders, eliminating the need for additional surface modification of the nanopowders and simplifying the coating preparation process.

[0043] 5. The performance of the AR film prepared by the wet coating process of the present invention is close to that of the imported AR film in terms of reflectivity and wear resistance. It can replace the imported AR film to achieve domestic production, thereby reducing the cost of the existing AR film. DETAILED DESCRIPTION

[0044] The scratch-resistant, stain-resistant, anti-reflective and anti-reflective coating is made of the following materials in percentage by weight: 50-77% epoxy oligomer; 20-40% spherical hollow nano-silicon dioxide; 1-5% nano-inorganic oxide; 1-5% fluorine / silicon compound; and 1-5% cationic photoinitiator. The particle size of the spherical hollow nano-silicon dioxide is between 20 and 200 nm.

[0045] The epoxy oligomer is one or more of epoxy glycidyl ether oligomer and epoxy cyclohexane oligomer; the nano inorganic oxide is one or more of solid silica, alumina, zirconium oxide, boron carbide, and silicon carbide; the particle size of the nano inorganic oxide is between 50 and 300 nm; the fluorine / silicon compound is one or more of epoxy fluorosilicone oil, epoxy siloxane, and fluorinated epoxy, and the fluorine / silicon compound must contain an epoxy group.

[0046] In order to make the technical concept and advantages of the invention more clearly understood, the technical solution of the present invention is further described in detail below. It should be understood that the following embodiments are only used to explain and illustrate the preferred embodiments of the present invention and should not constitute a limitation on the scope of the patent protection claimed in the present invention.

[0047] Example 1

[0048] The anti-scratch, anti-fouling, anti-reflective and anti-reflective coating of the present invention is made of the following materials in percentage by weight:

[0049]

[0050] The method for preparing the scratch-resistant, stain-resistant, anti-reflective and anti-reflective coating comprises the following steps:

[0051] S1. Add the epoxy oligomer into the mixer bucket according to the required weight ratio, start stirring, and set the speed to 500 rpm;

[0052] S2. Add the required amount of nano-inorganic oxide while stirring;

[0053] S3. After the addition is completed, the stirring speed of the stirrer is increased to 1000 rpm and stirred for 0.5 h;

[0054] S4, placing the stirred slurry into a sand mill for grinding until the nano-inorganic oxide is ground to the original nano-particle size;

[0055] S5. The ground slurry is transferred to a stirring barrel, and stirring is started, with the speed set to 500 rpm;

[0056] S6. Add the required amount of spherical hollow nano-silica while stirring, set the speed to 1000 rpm, and stir for 1 hour;

[0057] S7, after stirring is completed, add fluorine / silicon compound and cationic photoinitiator in sequence, and continue stirring at 300 rpm for 25 minutes;

[0058] S8, filtering and packaging, the obtained coating is a scratch-resistant, stain-resistant, anti-reflective and anti-reflective coating.

[0059] Tests were conducted using glass as the substrate. The coating in Example 1 was diluted to a solids content of 2-5% using an ester or ketone solvent before application. The test results in the table below show that a single-sided coating test was conducted using butyl acetate diluted to a solids content of 3%. UV curing was performed using 500mj / cm² of energy, and the reflectivity was 1.5%, meeting the requirements for LR applications (LR requires a reflectivity of ≤2.5%). The test results are compared with porous silica coatings, a commonly used anti-reflective and anti-reflective coating in China:

[0060] Reflectivity / % Transmittance / % <![CDATA[Resistant to steel wool 1 / 1KG]]> <![CDATA[Water contact angle 2 / °]]> Comparison 1 1.5 95.4 100 times, NG 110 Example 1 1.5 95.4 1000 times, OK 113

[0061] Remark:

[0062] Steel wool resistance 1: Use 0000# steel wool, test area 2cm*2cm, 1Kg load, 40 times / minute test speed. The judgment standard is to observe the sample at a 45° angle to the light after the test. If the number of scratches is ≤5, it is OK.

[0063] Water drop angle 2: The higher the water drop angle, the better the anti-fouling effect. Generally speaking, a water drop angle above 100° has a stain-resistant effect.

[0064] Example 2

[0065] The scratch-resistant, stain-resistant, anti-reflective and anti-reflective coating of this embodiment is different from that of Example 1 in that the proportion of spherical hollow silica is further increased to reduce the refractive index, thereby reducing the reflectivity and making the light transmittance higher.

[0066]

[0067] The method for preparing the scratch-resistant, stain-resistant, anti-reflective and anti-reflective coating comprises the following steps:

[0068] S1. Add the epoxy oligomer into the mixer bucket according to the required weight ratio, start stirring, and set the speed to 500 rpm;

[0069] S2. Add the required amount of nano-inorganic oxide while stirring;

[0070] S3. After the addition is completed, the stirring speed of the stirrer is increased to 800 rpm and stirred for 0.5 h;

[0071] S4, placing the stirred slurry into a sand mill for grinding until the nano-inorganic oxide is ground to the original nano-particle size;

[0072] S5. The ground slurry is transferred to a stirring barrel, and stirring is started, with the speed set to 500 rpm;

[0073] S6. Add the required amount of spherical hollow nano-silica while stirring, set the speed to 1000 rpm, and stir for 1.5 hours; the higher the proportion of spherical hollow nano-silica, the longer the stirring time after addition is required to mix evenly;

[0074] S7. After the stirring is completed, add the fluorine / silicon compound and the cationic photoinitiator in sequence, and continue stirring at a speed of 500 rpm for 15 minutes; after adding the cationic photoinitiator, the stirring speed should not be too high, and the stirring time should not be too short to avoid excessive temperature initiating the polymerization reaction;

[0075] S8, filtering and packaging, the obtained coating is a scratch-resistant, stain-resistant, anti-reflective and anti-reflective coating.

[0076] The test was conducted using optical PET with a total thickness of 53 μm and a 3 μm hardened layer as the substrate. During the application of the coating of Example 2, an ester or ketone solvent can be used to dilute the coating to a solid content of 2-5% before application. The test results in the table below are based on single-sided coating tests using butanone diluted to 3% solid content and UV curing using 700 mj / cm^2 energy. The test results are compared with those of fluorine-containing low-refractive index coatings, a commonly used anti-reflection and anti-reflection coating in China:

[0077] Reflectivity / % Transmittance / % Steel wool resistant* / 1KG Water drop angle / ° Comparison 2 1.4 95.6 10 times, NG 115 Example 2 1.3 95.9 1000 times, OK 114

[0078] Note: Use 0000# steel wool, test area 2cm*2cm, 1Kg load, 40 times / minute test speed. The judgment standard is to observe the sample at a 45° angle to the light after the test. If the number of scratches is ≤5, it is OK.

[0079] Example 3

[0080] The scratch-resistant, stain-resistant, anti-reflective, and anti-reflective coating of this embodiment differs from that of Example 1 in that the proportion of spherical hollow silica is further increased to reduce the refractive index. The proportion of solid silica is also slightly increased, thereby reducing the refractive index without compromising wear resistance.

[0081]

[0082] The method for preparing the scratch-resistant, stain-resistant, anti-reflective and anti-reflective coating comprises the following steps:

[0083] S1. Add the epoxy oligomer into the mixer bucket according to the required weight ratio, start stirring, and set the speed to 400 rpm;

[0084] S2. Add the required amount of nano-inorganic oxide while stirring;

[0085] S3. After the addition is complete, increase the stirring speed of the stirrer to 1200 rpm and stir for 1 hour;

[0086] S4, placing the stirred slurry into a sand mill for grinding until the nano-inorganic oxide is ground to the original nano-particle size;

[0087] S5. The ground slurry is transferred to a stirring barrel, and stirring is started, with the speed set at 300 rpm;

[0088] S6. Add the required amount of spherical hollow nano-silica while stirring, set the speed to 2000 rpm, and stir for 1 hour;

[0089] S7, after stirring is completed, add fluorine / silicon compound and cationic photoinitiator in sequence, and continue stirring at 800 rpm for 10 minutes;

[0090] S8, filtering and packaging, the obtained coating is a scratch-resistant, stain-resistant, anti-reflective and anti-reflective coating.

[0091] The test was conducted using optical PET with a total thickness of 53μm and a 3μm hardened layer as the substrate. When applying the coating in Example 3, ester or ketone solvents can be used to dilute the coating to a solid content of 2-5% before application. The test results in the table below show that the coating was diluted to 3% solid content with butanone for single-sided coating testing. UV curing was performed using 700mj / cm^2 energy, and the reflectivity was reduced to 0.9%, which can meet the AR (AR requires a reflectivity of ≤1.0%) application requirements while maintaining good scratch resistance. Compared with the previous examples, the proportion of hollow nano-silica in this example is increased, the cost is higher than other examples, and the reflectivity is reduced to a lower level, which can be used in applications with higher requirements.

[0092] Reflectivity / % Transmittance / % Steel wool resistant* / 1KG Water drop angle / ° Example 3 0.9 96.7 1000 times, OK 120

[0093] Compared to existing technologies, this invention offers the following advantages: while achieving reflectivity reduction, anti-reflection, and anti-reflection effects, the coating also maintains excellent scratch resistance. This addresses the shortcomings of existing anti-reflection and anti-reflection coatings and can be applied in applications requiring high scratch resistance. This also breaks Japan's monopoly on this type of coating.

[0094] The foregoing description is merely a preferred embodiment of the present invention and does not constitute a limitation of the present invention. Those skilled in the art, guided by the prior art, may make other modifications to the implementation of the present invention without inventive effort. Any modifications made within the spirit and principles of the present invention, or simple replacements or equivalent substitutions using conventional techniques in the art, shall be included within the scope of protection of the present invention.

Claims

1. A scratch-resistant, stain-resistant, anti-reflective, anti-reflective coating, characterized in that: Made of the following materials by weight: Epoxy oligomer 50-77%; 20-40% spherical hollow nano-silica; the particle size of the spherical hollow nano-silica is 20-200nm; 1-5% of nano-inorganic oxide; the nano-inorganic oxide has a spherical or elliptical shape and a particle size of 80-200 nm; the particle size of the nano-inorganic oxide must be 10-100 nm larger than the coating thickness; 1-5% of a fluorine / silicon compound; the fluorine / silicon compound is one or more of epoxy fluorosilicone oil, epoxy siloxane, and fluorinated epoxy resin, and the fluorine / silicon compound must contain an epoxy group; Cationic photoinitiator 1~5%.

2. The scratch-resistant, stain-resistant, anti-reflective, anti-reflective coating according to claim 1, characterized in that: The epoxy oligomer is selected from epoxy glycidyl ether oligomers containing epoxy groups and having three or more functions and / or epoxy cyclohexane oligomers.

3. The scratch-resistant, stain-resistant, anti-reflective, anti-reflective coating according to claim 1 or 2, characterized in that: The particle size of the spherical hollow nano-silica is 40-80 nm; the refractive index of the coating is adjusted by changing the proportion of the spherical hollow nano-silica, and the refractive index of the coating is controlled to be 1.25-1.

45.

4. The scratch-resistant, stain-resistant, anti-reflective, anti-reflective coating according to claim 3, characterized in that: The nano inorganic oxide is one or more of solid silicon dioxide, aluminum oxide, zirconium oxide, boron carbide and silicon carbide.

5. The scratch-resistant, stain-resistant, anti-reflective, anti-reflective coating according to claim 3, characterized in that: The nano inorganic oxide is made of solid silicon dioxide and / or aluminum oxide; the particle size of the nano inorganic oxide is 50 to 300 nm.

6. The scratch-resistant, stain-resistant, anti-reflective, anti-reflective coating according to claim 1, 2, 4 or 5, characterized in that: The cationic photoinitiator is selected from one or more of 4-isobutylphenyl-4'-methylphenyliodonium hexafluorophosphate, diphenyl-(4-phenylthio)phenylsulfonium hexafluoroantimonate, and diphenyl-(4-phenylthio)phenylsulfonium hexafluorophosphate.

7. The method for preparing the scratch-resistant, stain-resistant, anti-reflective and anti-reflective coating according to claim 1, characterized in that: Including steps: S1. Add the epoxy oligomer into the mixer bucket according to the required weight ratio, start stirring, and set the speed to 300-800 rpm; S2. Add the required amount of nano-inorganic oxide while stirring; S3. After the addition is completed, increase the stirring speed of the stirrer to 500-2000 rpm and stir for 0.5-1 hour; S4, placing the stirred slurry into a sand mill for grinding until the nano-inorganic oxide is ground to the original nano-particle size; S5. The ground slurry is transferred to a mixing barrel, and stirring is started, with the speed set at 300-800 rpm. S6. Add the required amount of spherical hollow nano-silica while stirring, set the speed to 500-2000 rpm, and stir for 1-2 hours; S7, after stirring is completed, add fluorine / silicon compound, cationic photoinitiator, speed 300 ~ 800rpm and continue stirring for 10 to 30min; S8, filtering and packaging, the obtained coating is a scratch-resistant, stain-resistant, anti-reflective and anti-reflective coating.

8. Use of the scratch-resistant, stain-resistant, anti-reflective and anti-reflective coating prepared by the preparation method of claim 1 or claim 7 in glass cover plates and solar cell glass plates.

9. Use of the scratch-resistant, stain-resistant, anti-reflective and anti-reflective coating prepared by the preparation method of claim 1 or claim 7 in a transparent plastic substrate.

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