High-hardness colored film and preparation method thereof

Abstract

The invention provides a high-hardness color film and a preparation method thereof, the color film comprises a light blocking layer and a modulation layer which are sequentially arranged on a substrate, and incident light enters from one side of the modulation layer; wherein the modulation layer is formed by alternately stacking a plurality of high-refractive-index absorption film layers and low-refractive-index dielectric film layers; the high-refractive-index absorption film layer is made of amorphous silicon-rich silicon nitride, and the low-refractive-index dielectric film layer is made of silicon nitride. According to the color film, reflection enhancement at a specific central wavelength is realized by utilizing an interference effect generated by alternately stacking high-hardness high-refractive-index film layers and low-refractive-index film layers; the light blocking layer realizes effective filtering of a specific wave band and color display which is not influenced by transmission color development. The color film is simple in structure, convenient to prepare, low in cost and suitable for batch production, and the production cost is greatly reduced; and absorption at different wave bands can be realized by adjusting the thickness of the modulation layer, so that reflection effects of different colors are realized, and films of various colors are obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of optical films, and in particular relates to a high-hardness colored film and a preparation method thereof. Background Art

[0002] Colors in nature usually come from three aspects, including pigments, bioluminescence and structural colors. The last type of color, which comes from surface structure, has received great attention in recent years. Structural color comes from the interaction between microstructure and light, and can be produced by a variety of mechanisms, such as surface plasmon resonance, Mie scattering of all-dielectric nanoparticles, diffraction structure or thin film interference. Unlike chemical color generation, structural color does not involve the participation of pigments or dyes, so there is no color fading phenomenon. At the same time, it can avoid the environmental pollution caused by the use of dyes and pigments, so it is widely used in decoration, printing and color development.

[0003] Although existing structural colors have the advantages of high brightness, high saturation and never fading. However, in some occasions, the durability of structural colors is an issue that cannot be ignored. In order to resist dust, sand, moisture, acid rain and salt spray, not only its optical properties should be considered, but also high durability (high hardness, high wear resistance, high temperature resistance, high corrosion resistance, etc.) is required. Among them, compared with other coloring technologies based on micro-nano structures, optical films based on interference effects do not require complex nano-processing manufacturing methods such as lithography, etching, milling or femtosecond laser writing, and have better durability. However, silicon (Si) and germanium (Ge) are usually used as absorption layers in general optical coatings; precious metals such as gold (Au), silver (Ag), copper (Cu) and aluminum (Al) are used as reflective layers. However, these materials are not hard enough to withstand mechanical wear and resist external erosion.

[0004] Silicon nitride (Si3N4) films are widely used in the mechanical field to enhance the durability of the workpiece surface and thus increase its service life due to their high hardness (up to 20GPa), good chemical stability, excellent corrosion and oxidation resistance, and high temperature resistance. At the same time, Si3N4 films have excellent optical properties, high transmittance and no absorption in the visible light range. They can be applied to the surface of solar panels to enhance the light absorption rate of solar panels. They can also be used to prepare transparent and anti-reflective films. They are the preferred material for preparing high-hardness films. However, the single color of silicon nitride films cannot meet the requirements of rich colors of films.

[0005] Therefore, there is an urgent need to develop a color film that has both high scratch resistance and high saturation over a large color gamut. Summary of the invention

[0006] In order to solve the problems existing in the prior art, the present invention provides a high-hardness color film and a preparation method thereof, wherein the spectral reflectivity of the high-hardness color film is about 50%, and the mechanical properties are good, the color saturation is high, and the film has excellent scratch resistance; the preparation method uses the radio frequency magnetron sputtering technology to prepare the color film, which can obtain a variety of different bright colors such as red (CIE1931 color coordinates ~ (0.56, 0.27)), green (CIE1931 color coordinates ~ (0.27, 0.52)), and blue (CIE1931 color coordinates ~ (0.16, 0.14)) according to actual needs, and the color gamut range is very large; and the preparation method is green and environmentally friendly, has high repeatability, and simple process, and is suitable for large-area and batch production.

[0007] A high-hardness color film comprises a light blocking layer and a modulation layer which are sequentially arranged on a substrate, and the incident light is incident from one side of the modulation layer;

[0008] Among them, the modulation layer is formed by alternatingly stacking multiple high-refractive index absorption film layers and low-refractive index dielectric film layers; the high-refractive index absorption film layer material is amorphous silicon-rich silicon nitride (MX), and the low-refractive index dielectric film layer material is silicon nitride (Si3N4), and the low-refractive index dielectric film layer has basically no absorption.

[0009] Silicon nitride thin films can be controlled by doping or changing deposition conditions to adjust their optical and electrical properties, and have good controllability. Based on this, the present invention uses silicon nitride thin films with different nitrogen contents to prepare high and low refractive index film layers, and uses multilayer film interference to produce structural colors, thereby obtaining a high-hardness colored film.

[0010] There is no limitation on the substrate material. The substrate may be made of glass materials such as K9, fused quartz, and float glass, semiconductor materials such as silicon and gallium arsenide, plastic materials such as PET, PC, and PI, or alloy materials such as stainless steel (such as alloys of chromium, titanium, tungsten, nickel, and germanium). Preferably, the substrate material is K9 or silicon.

[0011] Preferably, the refractive index of the high refractive index absorption film layer is 2.3 to 3.5, more preferably 2.5 to 3, and even more preferably 2.7.

[0012] Preferably, the single layer thickness of the high refractive index absorption film layer is 20 to 300 nm.

[0013] Preferably, the refractive index of the low-refractive-index medium film layer is 1.8 to 2.1, and more preferably 2. At this refractive index, the low-refractive-index medium film layer has no absorption.

[0014] Preferably, the single layer thickness of the low refractive index medium film layer is 20-300 nm.

[0015] Preferably, the light blocking layer material is one or more of silver, aluminum, platinum, chromium, titanium, tungsten, nickel, germanium, silicon, gallium nitride, gallium arsenide, Group II and Group III compounds, or alloys of the above metals, more preferably chromium or silicon.

[0016] Preferably, the light blocking layer material and the substrate material may be the same or different, and the total thickness of the substrate and the light blocking layer should be greater than 50 μm, more preferably greater than 500 μm, and even more preferably 500-1100 μm.

[0017] Preferably, the thickness of the light blocking layer is greater than 10 nm, more preferably greater than 20 nm, and in order to further reduce the transmittance of the film, more preferably, the thickness of the light blocking layer is 50 to 100 nm.

[0018] The present invention also provides a method for preparing the high-hardness colored film as described in any one of the above items, comprising the following steps:

[0019] (1) using radio frequency magnetron sputtering technology (vacuum coating) to prepare a single layer of low refractive index dielectric film and a high refractive index absorption film, respectively, and perform refractive index and thickness fitting to determine that the refractive index of the obtained film is the set refractive index, and at the same time obtain and save the corresponding preparation process conditions;

[0020] (2) Based on the preparation process conditions obtained in step (1), according to the requirements of the desired color film, the thickness of each layer of the film is optimized, and the structural parameters of the color film that meets the requirements are designed;

[0021] (3) After cleaning and drying the substrate, a light blocking layer and a modulation layer are sequentially deposited on the substrate using radio frequency magnetron sputtering technology according to the preparation process conditions determined in step (1) and the structural parameters obtained in step (2), thereby obtaining the high-hardness color film.

[0022] In the above step (2), the optimization of the thickness of each layer of the film and the design of the color film structure parameters can be achieved by using existing software (such as TFCalc, Optilayer).

[0023] In step (2), the requirements for the color film include bandwidth, absorptivity, reflectivity, chromaticity, brightness, etc.

[0024] In step (3), the substrate is wiped with an ethanol ether solution, cleaned and blown dry with an air gun before the corresponding film layer deposition can be performed.

[0025] In step (3), during the optimization phase or after the optimization is completed, the calculated color coordinates can be used to evaluate the film system parameters obtained after each deposition or finally obtained, so as to ensure the accuracy of the film system (color film) parameters obtained finally.

[0026] Preferably, in steps (1) and (3), when preparing the high refractive index absorption film layer, the argon gas is 0.5 to 100 sccm, the flow ratio of argon gas to nitrogen is (5:1) to (8:1), and the corresponding (silicon palladium) RF power density is 60 to 200 W / mm 2 As a further preference, when preparing a high refractive index absorption film layer, the argon gas is 1 to 10 sccm, the flow ratio of argon gas to nitrogen is (6:1) to (7:1), and the corresponding (silicon palladium) RF power density is 80 to 120 W / mm 2 .

[0027] Preferably, in steps (1) and (3), when preparing the low refractive index dielectric film layer, the argon flow rate is 0.5 to 100 sccm, the flow ratio of argon to nitrogen is (1:1) to (4:1), and the corresponding (silicon palladium) RF power density is 60 to 200 W / mm 2 As a further preference, when preparing a low refractive index dielectric film layer, the argon flow rate is 1 to 10 sccm, the flow ratio of argon to nitrogen is (2:1) to (3:1), and the corresponding (silicon palladium) RF power density is 120 to 160 W / mm 2 .

[0028] Preferably, the structural parameters of the color film include the number of film layers of the color film, the material of each film layer and the thickness of each film layer.

[0029] The preparation method of the above-mentioned colored film adopts radio frequency magnetron sputtering technology, and the substrate that has been wiped clean and dried is placed in a chamber. After evacuation, inert gases argon and nitrogen are introduced into the chamber, and the radio frequency magnetron sputtering source is turned on to deposit a light blocking layer and a modulation layer on the surface of the substrate in sequence; when depositing the modulation layer, the nitrogen content in the silicon nitride film layer and the thickness of the film layer are changed by adjusting the nitrogen flow rate, deposition power and deposition time, so as to prepare a colored film with good mechanical properties and high color saturation.

[0030] The method for preparing the high-hardness color film of the present invention can adjust the refractive index of the nitrogen silicon compound by controlling the amount of nitrogen introduced during the magnetron sputtering process to form a film stack with alternating high and low refractive indices, so that it can achieve high-saturation color display in the visible light band and has very high hardness. Therefore, the color film of the present invention can be widely used in the fields of decoration, display, etc.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] The high-hardness color film of the present invention utilizes the interference effect produced by the alternating stacking of high-refractive-index absorption film layers with high hardness and low-refractive-index dielectric film layers to achieve reflection enhancement at a specific central wavelength; while the light blocking layer can achieve wide-band cutoff outside the reflection band and reduce transmission, thereby achieving effective filtering of a specific band and color display that is not affected by transmission color development. By adjusting the thickness of the modulation layer, absorption in different bands can be achieved, thereby achieving reflection effects of different colors and obtaining films of various colors.

[0033] The method for preparing the colored film of the present invention can prepare a film of any desired color according to demand, and the film can also have a relatively high hardness (>21 GPa).

[0034] The high-hardness color film of the present invention has a simple structure, is easy to prepare, has low cost, and is suitable for large-scale batch production, thereby greatly reducing the preparation cost of the hard color film. The color film is expected to be widely used in decoration, color development, anti-counterfeiting and other fields, and contribute to the fields of my country's national economy, social development, science and technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 A schematic diagram of the structure of a high-hardness color film of the present invention;

[0036] Figure 2 The reflection spectrum of the red hard film prepared in Example 1 of the present invention; wherein the substrate is K9, the light blocking layer is chromium, and the regulating layer is composed of a high refractive index absorption film layer and a low refractive index medium film layer alternately distributed;

[0037] Figure 3 The reflection spectrum of the green hard film prepared in Example 2 of the present invention; wherein the substrate is silicon, the light blocking layer is chromium, and the regulating layer is composed of a high refractive index absorption film layer and a low refractive index medium film layer alternately distributed;

[0038] Figure 4 The reflection spectrum of the blue hard film prepared in Example 3 of the present invention; wherein the substrate and the light blocking layer are both made of silicon, and the regulating layer is composed of a high refractive index absorption film layer and a low refractive index medium film layer alternately distributed;

[0039] Figure 5 The nanoindenter indentation load-displacement curve of the red hard film prepared in Example 1 of the present invention, corresponding to a film hardness of 21.7 GPa;

[0040] Figure 6 The nanoindenter indentation load-displacement curve of the green hard film obtained in Example 2 of the present invention, corresponding to a film hardness of 22.1 GPa;

[0041] Figure 7The nanoindenter indentation load-displacement curve of the blue hard film prepared in Example 3 of the present invention corresponds to a film hardness of 21.3 GPa. DETAILED DESCRIPTION

[0042] The technical solution of the present invention is described in detail below in conjunction with the accompanying drawings.

[0043] like Figure 1 As shown, a high-hardness color film consists of a substrate, a light blocking layer, and a modulation layer formed by alternately stacking a plurality of high-refractive-index absorption film layers and low-refractive-index medium film layers.

[0044] There is no limitation on the substrate material, and glass materials such as K9, fused quartz, and float glass can be selected, semiconductor materials such as silicon and gallium arsenide can be selected, plastic materials such as PET, PC, and PI can be selected, and alloy materials such as stainless steel (such as alloys of chromium, titanium, tungsten, nickel, and germanium) can also be selected. The substrate material is preferably K9 or silicon.

[0045] The light blocking layer can be selected from one or more highly absorbing materials such as silver, aluminum, platinum, chromium, titanium, tungsten, nickel, germanium, silicon, gallium nitride, gallium arsenide, Group II and Group III compounds, or alloys of the aforementioned metals. The light blocking layer is preferably chromium or silicon.

[0046] In the following embodiments, the high refractive index absorption film layer is preferably amorphous silicon-rich silicon nitride (MX) with a refractive index of 2.7; the low refractive index dielectric film layer is preferably silicon nitride (Si3N4) with a refractive index of 2 close to the standard stoichiometric ratio.

[0047] A method for preparing a high-hardness colored film comprises the following steps:

[0048] 1) using radio frequency magnetron sputtering technology to prepare a single layer of low refractive index dielectric film layer and a high refractive index absorption film layer respectively, and performing refractive index and thickness fitting, determining that the refractive index of the obtained film layer is the set refractive index, and obtaining and saving the corresponding preparation process conditions;

[0049] 2) Based on the preparation process conditions obtained in step 1), according to the bandwidth, absorptivity, reflectivity, chromaticity, brightness and other requirements of the desired color film, the thickness of each film layer is optimized using TFCalc software, and a color film system that meets the requirements is designed to obtain the structural parameters of the color film including the total number of film layers (the number of film layers of the color film), the material of each film layer, and the thickness of each film layer;

[0050] 3) Wipe the substrate clean with an ethanol ether solution and blow dry with an air gun to obtain a base;

[0051] 4) Using radio frequency magnetron sputtering technology, according to the preparation process conditions determined in step 1) and the structural parameters obtained in step 2), a light blocking layer and a modulation layer are sequentially deposited on the substrate to finally obtain a high-hardness color film.

[0052] In the above step 1), the process conditions for obtaining a high refractive index amorphous silicon-rich silicon nitride with a refractive index of 2.7 are: argon flow rate of 2.55 sccm; argon to nitrogen flow ratio of 6.375:1; RF power density of 100 W / mm 2 .

[0053] The process conditions for achieving a refractive index of 2 for low refractive index non-absorption silicon nitride are: argon flow rate of 2.55sccm; argon to nitrogen flow ratio of 2.217:1; RF power density of 140W / mm 2 .

[0054] Example 1: A red hard film is pre-prepared, with an expected reflection band of 650nm to 680nm and an average reflectivity greater than 50%.

[0055] The red hard film is prepared by the above preparation method, wherein the substrate material used is K9, and the red hard film is composed of a light blocking layer (chromium is selected) and a regulating layer arranged in sequence on the substrate: |MX(40.7nm)|Si3N4(59.2nm)|MX(62.3nm)|Si3N4(78.3nm)|MX(72.6nm)|Si3N4(93.9nm)|MX(50.9nm)|Si3N4(53.1nm)|; wherein the thickness of chromium is 50nm, the thickness of the substrate is (1mm), and MX is amorphous silicon-rich silicon nitride.

[0056] The reflection spectrum of the red hard film prepared in this embodiment is as follows: Figure 2 As shown, its average reflectivity in the 650nm-680nm band is greater than 50%, its color coordinates are (0.56, 0.27), and its brightness L* is 24.2.

[0057] Example 2: A green hard film is pre-prepared, with an expected reflection band of 520nm to 550nm and an average reflectivity greater than 50%.

[0058] The green hard film is prepared by the above-mentioned preparation method (basically the same as Example 1, and the reflection band is changed by adjusting the thickness of different film layers), wherein the substrate material used is silicon, and the green hard film is composed of a light blocking layer (chromium is selected) and a regulating layer sequentially arranged on the substrate: |MX(26.6nm)|Si3N4(124.8nm)|MX(60.7nm)|Si3N4(107.6nm)|MX(19.4nm)|Si3N4(259.4nm)|; wherein the thickness of chromium is 50nm, the thickness of the substrate is (0.5mm), and MX is amorphous silicon-rich silicon nitride.

[0059] The reflection spectrum of the green hard film prepared in this embodiment is as follows: Figure 3 As shown, its average reflectivity in the 520nm-550nm band is greater than 50%, its color coordinates are (0.27, 0.52), and its brightness L* is 64.4.

[0060] Example 3: A blue hard film is pre-prepared, with an expected reflection band of 440-480 nm and an average reflectivity greater than 50%.

[0061] The blue hard film is prepared by the above-mentioned preparation method (basically the same as Example 1, and the reflection band is changed by adjusting the thickness of different film layers), wherein the substrate material and the light blocking layer used are both silicon, and the following compositions are arranged on the substrate and the light blocking layer: |MX(55.7nm)|Si3N4(72.4nm)|MX(40.3nm)|Si3N4(69.1nm)|MX(34.7nm)|Si3N4(93.3nm)|; the total thickness of the substrate and the light blocking layer is (0.51mm), and MX is amorphous silicon-rich silicon nitride.

[0062] The reflection spectrum of the blue hard film prepared in this embodiment is as follows: Figure 4 As shown, its average reflectivity in the 440-480 nm band is greater than 50%, its color coordinates are (0.16, 0.14), and its brightness L* is 40.4.

[0063] The colored films prepared in Examples 1 to 3 were tested using a nanoindenter. The results are as follows: Figures 5 to 7 As shown, the hardness of each color film was calculated using Indentation software. The hardnesses of the three color films prepared in Examples 1 to 3 were 21.7 Gpa, 22.1 Gpa, and 21.3 Gpa, respectively, all of which had relatively high hardness.

Claims

1. A high hardness colored film, characterized in that: It includes a light blocking layer and a modulation layer which are sequentially arranged on a substrate, and the incident light is incident from one side of the modulation layer; The modulation layer is formed by alternately stacking a plurality of high refractive index absorption film layers and low refractive index medium film layers; the high refractive index absorption film layer material is amorphous silicon-rich silicon nitride, and the low refractive index medium film layer material is silicon nitride.

2. The high-hardness colored film according to claim 1, characterized in that: The refractive index of the high refractive index absorption film layer is 2.3 to 3.5; The single layer thickness of the high refractive index absorption film layer is 20 to 300 nm.

3. The high-hardness colored film according to claim 1, characterized in that: The refractive index of the low-refractive-index medium film layer is 1.8 to 2.1; The single layer thickness of the low refractive index medium film layer is 20 to 300 nm.

4. The high-hardness colored film according to claim 1, characterized in that: The light blocking layer material is one or more of silver, aluminum, platinum, chromium, titanium, tungsten, nickel, germanium, silicon, gallium nitride, gallium arsenide, Group II and Group III compounds, or alloys of the aforementioned metals; The thickness of the light blocking layer is greater than 10 nm.

5. A method for preparing a high-hardness colored film according to any one of claims 1 to 4, characterized in that: The following steps are involved: (1) using radio frequency magnetron sputtering technology to prepare a single layer of low refractive index dielectric film and a high refractive index absorption film, respectively, and performing refractive index and thickness fitting to determine that the refractive index of the obtained film is the set refractive index, and at the same time obtain and save the corresponding preparation process conditions; (2) Based on the preparation process conditions obtained in step (1), according to the requirements of the desired color film, the thickness of each layer of the film is optimized, and the structural parameters of the color film that meets the requirements are designed; (3) After cleaning and drying the substrate, a light blocking layer and a modulation layer are sequentially deposited on the substrate using radio frequency magnetron sputtering technology according to the preparation process conditions determined in step (1) and the structural parameters obtained in step (2), thereby obtaining the high-hardness color film.

6. The method for preparing a high-hardness colored film according to claim 5, characterized in that: In steps (1) and (3), when preparing the high refractive index absorption film layer, the argon flow rate is 0.5 to 100 sccm, the flow ratio of argon to nitrogen is (5:1) to (8:1), and the corresponding RF power density is 60 to 200 W / mm 2 .

7. The method for preparing a high-hardness colored film according to claim 5, characterized in that: In steps (1) and (3), when preparing the low refractive index dielectric film layer, the argon flow rate is 0.5 to 100 sccm, the flow ratio of argon to nitrogen is (1:1) to (4:1), and the corresponding RF power density is 60 to 200 W / mm 2 .

8. The method for preparing a high-hardness colored film according to claim 5, characterized in that: The structural parameters of the color film include the number of film layers of the color film, the material of each film layer, and the thickness of each film layer.

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