A nano-composite coating and its preparation method and application

Abstract

The present invention relates to a nano-composite coating and its preparation method and application, belonging to the technical field of transparent conductive films. The present invention provides a preparation method of a nano-composite coating: using a mixture of niobium oxide and rare earth oxide, or niobium oxide doped with rare earth oxide as a target, and depositing the target on the surface of a substrate by sputtering to obtain the nano-composite coating. By adjusting the preparation parameters and the ratio of rare earth oxide to niobium oxide, a coating with good weather resistance, corrosion resistance and high optical transmittance can be prepared, which can be widely used in transparent conductive films to improve their weather resistance and broaden the application scope.

Description

Technical Field

[0001] The present invention relates to the technical field of transparent conductive films, and particularly relates to a nano-composite coating, a preparation method thereof, and an application thereof. Background Art

[0002] A transparent conductive film is a film that can both conduct electricity and has a high transparency rate in the visible light range. It mainly includes metal film systems, oxide film systems, other compound film systems, polymer film systems, composite film systems, etc. Such transparent conductive films are widely used in electronic devices such as touch screens and displays, new photovoltaics, electrochromic devices, optoelectronic thin films, transparent electromagnetic shielding coatings, and other fields. Currently, the most commonly used transparent conductive film is indium tin oxide (ITO) film, but it has problems of insufficient flexibility and conductivity. In addition, the emergence of metal nanowire conductive films has further promoted the development of transparent conductive films, especially the large-scale application of silver nanowire conductive films. However, silver nanowires are often prone to problems such as nanowire spheroidization, swelling and fracture, and silver migration under the influence of temperature, environment, and stress.

[0003] With the expansion of the application scenarios of transparent conductive films, the performance of transparent conductive films in terms of antioxidant and weather resistance has received more attention. To improve the weather resistance problem of transparent conductive films, on the basis of ensuring the performance indicators of existing conductive films, it is urgent to find a method to improve the antioxidant and weather resistance of conductive films. On this basis, developing a composite coating that can improve the weather resistance of transparent conductive films while maintaining good conductivity and transparency has a high application prospect in the field of transparent conductive films. Summary of the Invention

[0004] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a nano-composite coating, a preparation method thereof, and an application thereof. The nano-composite coating prepared by the preparation method provided by the present invention can significantly improve the weather resistance of the conductive film, and at the same time has an optical transmittance of more than 90%, and has high application value in transparent conductive films.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] In a first aspect, the present invention provides a preparation method of a nano-composite coating, including the following steps: depositing a target material on the surface of a substrate by sputtering to obtain the nano-composite coating; depositing a target material on the surface of a substrate by sputtering to obtain the nano-composite coating;

[0007] The target material is a mixture of niobium oxide and rare earth oxide, or the target material is niobium oxide doped with rare earth oxide; in the target material, the mass ratio of niobium oxide to rare earth oxide is (90 - 99.999):(0.001 - 10).

[0008] Niobium oxide is a material with high refractive index and transparency. Doping with rare earth elements can promote the formation of a passivation layer and improve the stability of chemical bonds. Among them, the rare earth element is one or more, including light rare earths: lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium; and heavy rare earths: gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium, yttrium. In the present invention, a target containing a specific ratio of rare earth oxide and niobium oxide is used, and the target is deposited on a substrate by sputtering method to prepare a nano-composite coating with a specific thickness, which can significantly improve the oxidation resistance and weather resistance of the substrate surface.

[0009] The target is a mixture of niobium oxide and rare earth oxide, or directly uses niobium oxide doped with rare earth oxide as the target; the purity of the target is above 99.99%. The chemical formula of the rare earth oxide is ReO y , where Re represents a rare earth element, which is at least one of the above-listed rare earth elements; the chemical formula of the niobium oxide is NbO x (1≤x≤2.5), and the valence of Nb in the target and the coating can be +2, +3 or +5, or a combination of multiple valence states.

[0010] Controlling the specific ratio of niobium oxide and rare earth oxide can ensure the transparency of the coating while improving the weather resistance of the base layer. If the rare earth oxide is not doped, the weather resistance of the coating will be significantly deteriorated; if the proportion of the rare earth oxide is too high, the optical transmittance will be lower than 90%, affecting the optical properties of the substrate.

[0011] The nano-composite coating obtained by the above preparation method has good weather resistance, conductivity and optical properties: the coating has a high optical transmittance at a wavelength of 550nm, and is widely applicable to transparent conductive films; the haze of the coating ≤3%, and the conductivity and optical transmittance performance are good; under high temperature and high humidity conditions, it can protect the conductivity of the base layer for more than 110h, improving the weather resistance of the base layer, and has high application value in transparent conductive films.

[0012] Preferably, among the rare earth oxides, the rare earth element is cerium. At this time, the chemical formula of the rare earth oxide is CeO y (1.5≤y≤2). The Ce element in the target and the coating may be +3, +4 valence or a mixed valence state.

[0013] Further preferably, the target is niobium oxide doped with CeO2.

[0014] Preferably, the preparation method of the rare earth oxide-doped niobium oxide is at least one of melting method, powder metallurgy method, high-current heating method, hot isostatic pressing sintering method, hot pressing sintering method, sputtering reaction method.

[0015] Further preferably, the preparation method of the rare earth oxide-doped niobium oxide is the melting method or the sputtering reaction method. It is easier to prepare the above-mentioned high-purity rare earth oxide-doped niobium oxide target by the melting method or the sputtering reaction method.

[0016] Preferably, the substrate is one or a combination of a transparent polymer film, a metal nanowire conductive film, a metal grid conductive film, and a transparent conductive oxide conductive film.

[0017] Further preferably, the substrate is one or a combination of a transparent polymer film, a metal nanowire conductive film, an ITO conductive film, an FTO conductive film, and an AZO conductive film.

[0018] Preferably, the substrate is cleaned before preparation. It is cleaned with acetone, ethanol, and deionized water in sequence for 15 minutes, and then dried with high-purity nitrogen for use.

[0019] Using the above conductive transparent film as the substrate, the nano-composite coating is formed by sputtering, which can significantly improve the weather resistance of the substrate, does not affect the optical properties of the substrate, and broadens its application range.

[0020] Preferably, in the target, the mass ratio of niobium oxide to rare earth oxide is (95 - 99.999):(0.001 - 5). Further preferably, the mass ratio of the niobium oxide to the rare earth oxide is 99.5:0.5.

[0021] Within the preferred ratio range of niobium oxide to the rare earth oxide, the weather resistance of the coating is better. Further increasing the ratio of rare earth oxide will result in worse weather resistance.

[0022] Preferably, the specific steps of the sputtering method are as follows: the sputtering chamber filled with the target is evacuated, and then argon is introduced to control the pressure for sputtering; the vacuum degree of the sputtering chamber is 2.0×10 -4 -1.5×10 -3 Pa, the rate of introducing argon is 10 - 100 sccm, the gas flow pressure of argon is 0.1 - 10 Pa, and the sputtering power is 10 - 100 W.

[0023] Further preferably, the vacuum degree of the sputtering chamber is 2.0×10 -4 -1.0×10 -3 Pa, the rate of introducing argon is 10 - 50 sccm, the gas flow pressure of argon is 0.5 - 5 Pa, and the sputtering power is 30 - 100 W.

[0024] Preferably, the distance between the substrate and the target is 40 - 100 mm.

[0025] Further preferably, the distance between the substrate and the target is 60 - 80 mm.

[0026] During sputtering, controlling the distance between the target and the substrate within 40 - 100 mm can improve the weather resistance of the formed coating. If the distance is too small, it may cause damage to the coating and affect its use performance; if the distance is too large, the bonding will be weak, the bonding and protection effect on the substrate will become poor, and the weather resistance will decrease significantly. When the distance between the substrate and the target is 60 - 80 mm, it is more appropriate and the effect is optimal.

[0027] In a second aspect, the present invention provides a nanocomposite coating prepared by the preparation method of the above-mentioned nanocomposite coating.

[0028] Preferably, the thickness of the nanocomposite coating is 40 - 80 nm.

[0029] The thickness of the prepared nanocomposite coating has a great influence on the weather resistance and optical transmittance of the coating. When the coating thickness is lower than the defined range, the weather resistance of the coating decreases significantly, and its conductivity will be affected within 80 h under high temperature and high humidity conditions; if the coating thickness is too high, the optical transmittance will be too low to be widely applied to various transparent conductive films.

[0030] Further preferably, the transmittance of the nanocomposite coating at a wavelength of 550 nm is more than 90%.

[0031] When the coating thickness is controlled within 40 - 80 nm, the optical transmittance at a wavelength of 550 nm is more than 90%, and the light transmission and comprehensive effect are optimal, with a wide application range.

[0032] The prepared coating can be applied to transparent conductive films, maintaining an optical transmittance of more than 90%, and significantly improving its antioxidant property and weather resistance, ensuring the optical and conductive properties of the transparent conductive film during long-term use. It can be further applied to touch screens, displays, new photovoltaics, electrochromic devices, optoelectronic thin films, transparent electromagnetic shielding coatings, etc., with high practical value.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] The present invention combines the advantages of niobium oxide and rare earth oxides to provide a coating that can improve the performance of transparent conductive films. The nanocomposite coating prepared by the method provided by the present invention has high conductivity and transmittance, and at the same time has excellent corrosion resistance and weather resistance. Moreover, the process is simple, the cost is low, and it is suitable for industrial production. Detailed Embodiments

[0035] To better illustrate the purpose, technical solution and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments. The test methods used in the following embodiments are all conventional methods unless otherwise specified; the materials, reagents, etc. used are all reagents and materials that can be obtained from commercial channels unless otherwise specified.

[0036] In the following examples and comparative examples, the substrate used is an ITO-PET film with a sheet resistance of 10 Ω / sq and an optical transmittance of 92% at a wavelength of 550 nm.

[0037] Example 1

[0038] An embodiment of the nano-composite coating and its preparation method of the present invention. The preparation method of the nano-composite coating described in this embodiment is as follows:

[0039] (1) Using the ITO-PET film as the substrate, wash it with acetone, ethanol, and deionized water for 15 minutes in sequence, dry it with high-purity nitrogen, and fix it on the magnetron sputtering sample stage;

[0040] (2) Prepare a NbO target doped with rare earth oxide CeO2 by the melting method, load the target into the sputtering cavity and fix it, and control the distance between the substrate and the target to be 60 mm; The mass ratio of NbO and rare earth oxide is 99.5:0.5; x target, load the target into the sputtering cavity and fix it, and control the distance between the substrate and the target to be 60 mm; NbO x and rare earth oxide is 99.5:0.5;

[0041] (3) Pump the vacuum degree of the sputtering cavity of the magnetron sputtering instrument to 2.0×10 -4 Pa, then introduce argon at a rate of 30 sccm, control the pressure to 0.5 Pa, the sputtering power to 70 W, and sputter and deposit the target on the surface of the substrate at room temperature, and control the thickness to 60 nm;

[0042] (4) After the deposition in step (3) is completed, the sputtering cavity is inflated, the chamber door is opened to take out the film, and the nano-composite coating is obtained on the surface of the substrate.

[0043] Example 2

[0044] The difference between Example 2 and Example 1 is only that the rare earth oxides are CeO2 and Y2O3.

[0045] Example 3

[0046] An embodiment of the nano-composite coating and its preparation method of the present invention. The preparation method of the nano-composite coating described in this embodiment is as follows:

[0047] (1) Using the ITO-PET film as the substrate, wash it with acetone, ethanol, and deionized water for 15 minutes in sequence, dry it with high-purity nitrogen, and fix it on the magnetron sputtering sample stage;

[0048] (2) Load the NbO x / CeO2 mixed target into the sputtering chamber and fix it, and control the distance between the substrate and the target to be 60 mm; NbO x and the rare earth oxide have a mass ratio of 99.5:0.5;

[0049] (3) Pump the vacuum of the sputtering chamber of the magnetron sputtering instrument to 2.0×10 -4 Pa, then introduce argon at a rate of 30 sccm, control the pressure to be 0.5 Pa, the sputtering power to be 90 W, and sputter-deposit the target on the surface of the substrate at room temperature, and control the thickness to be 80 nm;

[0050] (4) After the deposition in step (3) is completed, inflate the sputtering chamber, open the chamber door to take out the film, and obtain the nano-composite coating on the surface of the substrate.

[0051] Example 4

[0052] The difference between Example 4 and Example 1 is only that the distance between the substrate and the target is 40 mm.

[0053] Example 5

[0054] The difference between Example 5 and Example 1 is only that the distance between the substrate and the target is 80 mm.

[0055] Example 6

[0056] The difference between Example 6 and Example 1 is only that the distance between the substrate and the target is 100 mm.

[0057] Example 7

[0058] The difference between Example 7 and Example 1 is only that NbO x and the rare earth oxide CeO2 have a mass ratio of 90:10.

[0059] Example 8

[0060] An embodiment of the nano-composite coating and its preparation method of the present invention. The preparation method of the nano-composite coating described in this embodiment is as follows:

[0061] (1) Use an ITO-PET film as the substrate, clean it with acetone, ethanol, and deionized water in sequence for 15 min, dry it with high-purity nitrogen, and fix it on the magnetron sputtering sample stage;

[0062] (2) Prepare a NbO target doped with rare earth oxide CeO2 by the melting method, load the target into the sputtering chamber and fix it, and control the distance between the substrate and the target to be 50 mm; NbO x target, load the target into the sputtering chamber and fix it, and control the distance between the substrate and the target to be 50 mm; NbO xThe mass ratio with the rare earth oxide is 99.5:0.5;

[0063] (3) Pump the vacuum degree of the sputtering cavity of the magnetron sputtering instrument to 2.0×10 -4 Pa, then introduce argon at a rate of 30 sccm, control the pressure to 0.5 Pa, the sputtering power to 80 W, and sputter and deposit the target material on the surface of the substrate at room temperature, and control the thickness to 80 nm;

[0064] (4) After the deposition in step (3) is completed, inflate the sputtering cavity, open the chamber door to take out the film, and obtain the nano-composite coating on the surface of the substrate.

[0065] Comparative Example 1

[0066] The difference between Comparative Example 1 and Example 1 is only that the target material is not doped with rare earth oxide.

[0067] Comparative Example 2

[0068] The following method is used to prepare a coating on the ITO-PET film:

[0069] (1) Use the ITO-PET film as the substrate, clean it with acetone, ethanol, and deionized water in turn for 15 min, dry it with high-purity nitrogen, and fix it on the magnetron sputtering sample stage;

[0070] (2) Load the NbO x / CeO2 mixed target material into the sputtering cavity and fix it, and control the distance between the substrate and the target material to 20 mm; NbO x The mass ratio with the rare earth oxide is 99.5:0.5;

[0071] (3) Pump the vacuum degree of the sputtering cavity of the magnetron sputtering instrument to 2.0×10 -4 Pa, then introduce argon at a rate of 60 sccm, control the pressure to 6 Pa, the sputtering power to 30 W, and sputter and deposit the target material on the surface of the substrate at room temperature, and control the thickness to 50 nm;

[0072] (4) After the deposition in step (3) is completed, inflate the sputtering cavity, open the chamber door to take out the film, and obtain a coating on the surface of the substrate.

[0073] Comparative Example 3

[0074] The difference between Comparative Example 3 and Example 1 is only that the distance between the substrate and the target material is 20 mm.

[0075] Comparative Example 4

[0076] The difference between Comparative Example 4 and Example 1 is only that the distance between the substrate and the target material is 150 mm.

[0077] Comparative Example 5

[0078] The difference between Comparative Example 5 and Example 1 is only that the mass ratio of NbO x and rare earth oxide CeO2 is 80:20.

[0079] Comparative Example 6

[0080] The difference between Comparative Example 6 and Example 1 is only that the sputtering power is 20 W and the thickness of the coating layer is controlled to be 20 nm.

[0081] Comparative Example 7

[0082] The difference between Comparative Example 7 and Example 1 is only that the sputtering power is 100 W and the thickness of the coating layer is controlled to be 150 nm.

[0083] Comparative Example 8

[0084] The difference between Comparative Example 8 and Example 8 is only that the sputtering power is 100 W and the thickness of the coating layer is controlled to be 100 nm.

[0085] Effect Example 1

[0086] To explore whether the light transmittance of the coating layers prepared in the above examples and comparative examples meets the application requirements of the transparent conductive film, the optical transmittance of the coating layers at 550 nm was measured. The results are shown in Table 1.

[0087] If the optical transmittance of the coating layer at a wavelength of 550 nm is above 90%, it is considered to pass and can be widely applied to the transparent conductive film in practice.

[0088] Effect Example 2

[0089] To explore the weather resistance of the coating layers prepared in the above examples and comparative examples, the sheet resistance of the conductive film was measured under high-temperature treatment at a relative humidity of 85% and 85 °C, and the retention time of the sheet resistance was recorded. The results are shown in Table 1.

[0090] The longer the retention time of the sheet resistance, the longer the retention time of the conductive performance and the better the weather resistance.

[0091] Table 1 Test results of light transmittance and weather resistance

[0092]

[0093] As can be seen from Table 1:

[0094] (1) Examples 1, 8 and Comparative Examples 6 - 8: Within the range of coating thickness defined by the present invention, the nano-composite coating has good weather resistance and optical properties. Under the high-temperature treatment at a relative humidity of 85% and 85 °C, the sheet resistance retention time is 140 - 150 h, and the optical transmittance is above 90%, which has a wider application in transparent conductive films. However, when the coating thickness is too low, the weather resistance deteriorates significantly; when the thickness is too high, the optical transmittance is too low to be widely applied in transparent conductive films.

[0095] (2) From Examples 1, 7 and Comparative Example 5, it can be seen that controlling the mass ratio of niobium oxide to the rare earth oxide has a great influence on the properties of the prepared nano-composite coating. Within the ratio range defined by the present invention, the nano-composite coating has high light transmittance, and at the same time has excellent corrosion resistance and weather resistance; too high doping amount may affect the light transmittance of the coating.

[0096] (3) From Examples 1, 4, 5 and Comparative Examples 3 - 4: Controlling the distance between the substrate and the target within a defined range during sputtering is beneficial to the service performance of the nano-composite coating; too large or too small distance will significantly deteriorate the coating performance. Within the preferred distance range of 60 - 80 mm between the substrate and the target, the sheet resistance retention time is above 120 h.

[0097] (4) From Examples 1 - 3: The target material can be a mixture of niobium oxide and rare earth oxide, or niobium oxide doped with rare earth oxide; the rare earth oxide can be an oxide of a single rare earth element or an oxide containing multiple rare earth elements. When the target material is niobium oxide doped with CeO2, the weather resistance effect is optimal.

[0098] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present invention rather than to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a nano-composite coating, characterized in that, It includes the following steps: The sputtering chamber containing the target is evacuated, and then argon is introduced to control the pressure for sputtering, depositing the target on the surface of the substrate to obtain the nano-composite coating; The target is a mixture of niobium oxide and cerium dioxide, or the target is niobium oxide doped with cerium dioxide; in the target, the mass ratio of niobium oxide to cerium dioxide is (90 - 99.999):(0.001 - 10); The substrate is one or a combination of a transparent polymer film, a metal nanowire conductive film, a metal grid conductive film, and a transparent conductive oxide conductive film; The distance between the substrate and the target is 40 - 100 mm.

2. The preparation method of the nano-composite coating according to claim 1, characterized in that, In the target, the mass ratio of niobium oxide to rare earth oxide is (95 - 99.999):(0.001 - 5).

3. The preparation method of the nano-composite coating according to claim 1, characterized in that, The vacuum degree of the sputtering chamber is 2.0×10 -4 -1.5×10 -3 Pa, the rate of introducing argon gas is 10 - 100 sccm, the gas flow pressure of the argon gas is 0.1 - 10 Pa, and the sputtering power is 10 - 100 W.

4. The preparation method of the nano-composite coating according to claim 1, characterized in that, The distance between the substrate and the target is 60 - 80 mm.

5. A nano-composite coating prepared by the method for preparing a nano-composite coating according to any one of claims 1 - 4.

6. The nano-composite coating according to claim 5, characterized in that, The thickness of the nano-composite coating is 40 - 80 nm.

7. The nano-composite coating according to claim 6, wherein The light transmittance of the nano-composite coating at a wavelength of 550 nm is more than 90%.

8. Application of the nano-composite coating according to any one of claims 5 - 7 in a transparent conductive film.

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