SiO2 / CNC multiple optical characteristic composite film and resin packaging preparation method

Abstract

The invention discloses a SiO2 / CNC multi-optical characteristic composite film and a resin packaging preparation method, and the preparation method comprises the steps: firstly, preparing a SiO2 photonic crystal film based on polydisperse nano silicon dioxide of which the particle size is in specific normal distribution; and jointly assembling the rolled CNC photon microchip, polydisperse SiO2 with the particle size in specific normal distribution and a toughening material. According to the method, the brittleness of a CNC chiral photon film is utilized, and the chiral photon microchip which is unique in shape, gorgeous in structural color, gorgeous in circular dichroism and fine in fingerprint texture texture is prepared through rolling treatment. According to the combination mode, the influence of all components in the SiO2 system on the CNC film-forming property, the screw pitch controllability and the structural uniformity is eliminated, and finally the SiO2 / CNC composite film with multiple optical characteristics and excellent mechanical properties is obtained.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical encryption and anti-counterfeiting, and particularly relates to a SiO 2 / CNC multiple optical feature composite film and a resin encapsulation preparation method thereof. Background Art

[0002] Natural cellulose is the most abundant biomass resource on earth. Cellulose nanocrystals (CNC) are a kind of nanoscale cellulose extracted from natural fibers. It not only has the characteristics of nanoparticles, but also has unique strength and optical properties, and has great application potential in optical devices, anti-counterfeiting, and structural coatings. It has broad application prospects. Cellulose nanocrystals can retain the left-handed nematic structure in the solid film through evaporation-induced self-assembly (EISA). When the pitch of the chiral nematic structure matches the wavelength of visible light, the material can selectively reflect left-handed circularly polarized light, producing an iridescent effect and forming a structural color film with unique optical properties. SiO 2 With its uniform spherical geometry and small particle size, it exhibits excellent dispersibility. Under appropriate charge density and particle concentration, it spontaneously arranges into a regular periodic structure of photonic crystals, thus producing gorgeous structural colors.

[0003] With the expansion of the research on optical materials, traditional single-functional optical property materials can no longer meet the current diversified production needs. Based on the above optical characteristics of the two, if the two can be compounded, a film with dual optical characteristics can be obtained. However, the compatibility between CNC and SiO 2 is poor, which will mutually destroy the self-assembled photonic crystal structures of the two, and the self-filming of CNC itself has certain brittleness. Therefore, a way to solve this problem needs to be sought. Summary of the Invention

[0004] The purpose of the present invention is to overcome the above-mentioned disadvantages of the prior art and provide a SiO 2 / CNC multiple optical feature composite film and a resin encapsulation preparation method thereof to solve the problems of poor mechanical properties of CNC films and difficult control in the assembly process in the prior art.

[0005] To achieve the above purpose, the present invention adopts the following technical solutions: A resin encapsulation preparation method of a SiO 2 / CNC multiple optical feature composite film includes the following steps: Step 1, coating a silica microsphere absolute ethanol dispersion on a substrate, and self-assembling the silica microspheres to obtain SiO 2 photonic crystals; Step 2, spin-coating a first resin on the SiO 2 photonic crystals, and drying after spin-coating to obtain SiO2 Photonic crystal thin film; Step 3: Evaporate and induce the CNC aqueous dispersion, and self-assemble to obtain a CNC photonic thin film. After crushing the CNC photonic thin film, micron-sized fragments are obtained, which are CNC microchips; Step 4: Add the CNC microchips to the second resin, stir to obtain a mixed system, and spin-coat the mixed system on the SiO 2 photonic crystal thin film. After drying, a CNC photonic microchip thin film is prepared on the SiO 2 photonic crystal thin film, and a SiO 2 / CNC multiple optical feature composite thin film is obtained.

[0006] A further improvement of the present invention lies in: Preferably, in step 1, the particle size of the silica microspheres in the silica microsphere anhydrous ethanol dispersion is normally distributed; the mass fraction of the silica microsphere anhydrous ethanol dispersion is 0.3-20%.

[0007] Preferably, the specific process of step 1 is to coat the silica microsphere anhydrous ethanol dispersion on the substrate by drop coating, spraying or spin coating, and obtain a SiO 2 photonic crystal thin film after drying.

[0008] Preferably, in step 2, the spin coating speed of the first resin is 1500-3000 rpm, and the spin coating time is 1-80 s.

[0009] Preferably, the first resin and the second resin are one or more of phenolic resin, acrylic resin, phthalonitrile resin, epoxy resin, and polyester resin.

[0010] Preferably, in step 3, the mass fraction of the CNC aqueous dispersion is 2-20%.

[0011] Preferably, in step 3, the evaporation temperature is 20-80 °C.

[0012] Preferably, in step 4, the spin coating speed is 1500-3000 rpm.

[0013] Preferably, in step 4, the drying temperature is 20-80 °C.

[0014] A SiO 2 / CNC multiple optical feature composite thin film prepared by the resin encapsulation preparation method described in any one of the above, comprising a lower layer of SiO 2 photonic crystal thin film and an upper layer of CNC photonic microchip thin film.

[0015] The present invention has the following beneficial effects compared with the prior art: The present invention discloses a SiO2 / CNC multi-optical characteristic composite film resin encapsulation preparation method, the preparation method firstly prepares SiO based on polydisperse nano-silicon dioxide with a specific normal distribution of particle size 2 Photonic crystal film, and then with the help of the toughening properties of resin materials, the rolled CNC photonic micro-chips and polydisperse SiO 2 This method uses the brittleness of CNC chiral photonic films to prepare chiral photonic microsheets with unique shapes, colorful structures, brilliant circular dichroism, and fine fingerprint textures through rolling treatment. This combination eliminates the need for SiO 2 The influence of each component in the system on the CNC film forming property, pitch controllability, and structural uniformity, and finally obtains SiO with multiple optical properties and excellent mechanical properties. 2 / CNC composite film. The layer stacking method used in this method has a simple process, is easy to mass produce, has multiple optical anti-counterfeiting functions, and has great application potential in the fields of optical anti-counterfeiting, optical encryption and decoration.

[0016] The invention also discloses a SiO 2 / CNC composite film with multiple optical characteristics. The composite film utilizes the brittleness of CNC chiral photonic film and combines it with polydisperse nano-silica through rolling treatment. At the same time, it retains the characteristic structure of silica and cellulose nanocrystals. It expresses different optical properties under the excitation of point light source, natural light and polarized light, respectively, and realizes the superposition of optical characteristics. The bright structural color of CNC microsheets can be observed under natural light and polarized light, while the CNC structural color is hidden under point light source, and only SiO 2 The gorgeous iridescent effect is used to realize pattern display, which has multiple anti-counterfeiting effects.

[0017] Furthermore, resin is encapsulated on the prepared photonic crystal film, and the resin encapsulation can improve the transparency of the film and enhance the iridescence effect of the silicon dioxide film.

[0018] Furthermore, the CNC photonic crystal film is assembled at a certain temperature, and its inherent brittleness is utilized to break it into micron-sized photonic microchips of uneven size and irregular shape by rolling. The resin is mixed with the CNC microchips and coated on the surface of the silicon dioxide photonic crystal. The resin protects the micron-sized photonic microchips without affecting the SiO 2 The structure of the coating gives clear boundaries to the characters. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The SiO2 with different oxygen plasma treatment durations under black background in Example 1 of the present invention 2 Photo of the assembly on a glass substrate.

[0020] Figure 2 This is a photo of the assembly of SiO on a PET substrate under a black background with different oxygen plasma treatment durations in Example 4 of the present invention. 2 Photo of the assembly on a PET substrate.

[0021] Figure 3 This is a photo of the coating prepared by the drop - coating method on a glass substrate with 0.3 wt% SiO in Example 6 of the present invention. 2 Optical photo of the coating prepared by the drop - coating method on a glass substrate (left: pattern background; right: point source).

[0022] Figure 4 This is a photo of the coating prepared by the drop - coating method on a glass substrate with 0.6 wt% SiO in Example 7 of the present invention. 2 Optical photo of the coating prepared by the drop - coating method on a glass substrate (left: pattern background; right: point source).

[0023] Figure 5 This is a photo of the assembled SiO on a glass substrate in Example 8 of the present invention. 2 Optical photo of the photon crystal coating on a glass substrate after resin coating (left: pattern background; right: point source).

[0024] Figure 6 This is a photo of the coating prepared by the spraying method on a glass substrate with 0.3 wt% SiO in Example 9 of the present invention, (a) pattern background; (b) black background; (c) point source. 2 Optical photo of the coating prepared by the spraying method on a glass substrate, (a) pattern background; (b) black background; (c) point source.

[0025] Figure 7 This is a photo of the assembled photon crystal coating on a glass substrate after resin coating with 0.3 wt% SiO in Example 11 of the present invention and a super - depth - of - field micrograph, (a) pattern background; (b) point source; (c)-(d) are super - depth - of - field micrographs: (c1) and (d1) are 2D and 3D maps of the uncoated resin respectively; (c2) and (d2) are 2D and 3D maps of the coated resin respectively. 2 Optical photo and super - depth - of - field micrograph of the patterned application of SiO / CNC coating on a substrate in Example 12 of the present invention, (a) black background; (b) point source.

[0026] Figure 8 This is a photo of SiO in Example 12 of the present invention. 2 Optical photo of the patterned application of SiO / CNC coating on a substrate, (a) black background; (b) point source. Detailed implementation manners

[0027] The following further describes the present invention in detail with reference to the accompanying drawings: To enable those skilled in the art to understand the features and effects of the present invention, the following provides a general description and definition of the terms and phrases mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used herein shall have the ordinary meaning understood by those skilled in the art for the present invention. In case of conflict, the definition in this specification shall prevail.

[0028] In this text, unless otherwise specified, the terms "comprise", "include", "contain", "have" or similar terms cover the meanings of "consist of" and "consist essentially of". For example, "A comprises a" covers the meanings of "A comprises a and others" and "A consists only of a".

[0029] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

[0030] Conventional instruments and equipment in the art are used in the following embodiments. For the experimental methods without specific conditions noted in the following embodiments, they are usually carried out under conventional conditions or according to the conditions recommended by the manufacturer. Various raw materials are used in the following embodiments. Unless otherwise stated, commercially available products are used, and their specifications are conventional specifications in the art. In the specification of the present invention and the following embodiments, unless otherwise specified, "%" represents weight percentage, "parts" represents weight parts, and the ratio represents weight ratio.

[0031] The present invention discloses a preparation method of a SiO 2 / CNC composite film. Utilizing the brittleness of the CNC chiral photon film, the rolled CNC photon microchips are co-assembled with SiO 2 and encapsulated with resin, and the composite film is toughened. For the composite optical film, the bright structural color of the CNC microchips can be observed under natural light and polarized light, while the CNC structural color is hidden under a point light source, and only the gorgeous iridescent effect of SiO 2 can be seen, having multiple optical characteristics. In addition, the mechanical properties of the film are excellent, which is beneficial to practical applications. The preparation method specifically includes the following steps: (1) Prepare polydisperse silica with a specific normal distribution of particle size by the multi-step dropwise addition of precursor solution method. The specific method and steps can be seen in the patent "A Photochromic Coating and Its Preparation Method" (ZL 202110224660.8).

[0032] (2) After mixing silica and absolute ethanol, a silica absolute ethanol dispersion with a mass fraction of 0.3-20% is obtained after ultrasonic treatment, and the ultrasonic treatment time is 30 min. (3) Clean the experimental substrate and dry it in an oven, and perform oxygen plasma treatment for (1-30) min. The experimental substrate is any one of a glass sheet, polyethylene terephthalate (PET), polypropylene (PP), or polyvinyl chloride (PVC).

[0033] In this process, when assembling the silica photonic crystal, the silica is subjected to oxygen plasma treatment on different substrates for different durations to increase the hydrophilicity of the substrate surface, ensure the uniform diffusion of the solvent on the substrate surface, and obtain a photonic crystal film with a flat surface and good stability.

[0034] (4) Assemble and prepare SiO 2 photonic crystals on the substrate by drop coating, spraying or spin coating.

[0035] The process of preparing SiO 2 photonic crystals by drop coating is as follows: Drop 0.1 - 30 μL of SiO 2 ethanol dispersion (0.3 - 20 wt%) on the experimental substrate treated in (3), and wait for it to dry to obtain the assembled SiO 2 photonic crystals.

[0036] The process of preparing SiO 2 photonic crystals by spraying is as follows: Spray 1 - 10 mL of SiO 2 ethanol dispersion (0.3 - 20 wt%) on the experimental substrate treated in (3), and wait for it to dry to obtain the assembled SiO 2 photonic crystals.

[0037] (6) Use a pipette to take 1 - 10 ml of the first resin and drop it at the center position of the substrate with a SiO 2 coating, spin coat at a speed of 1500 - 3000 rpm for 1 - 80 s, and after spin coating, place it in an oven at 20 - 80 °C for sufficient drying. After curing, the encapsulation of the SiO 2 photonic crystal film is completed. The resin is one or several of phenolic resin, acrylic resin, phthalonitrile resin, epoxy resin or polyester resin.

[0038] (7) Pour 2 - 20% CNC aqueous dispersion into a polystyrene petri dish, and perform evaporation-induced self-assembly at 20 - 80 °C to obtain a CNC photonic film. After drying, crush it into irregular fragments with micron-sized dimensions by rolling to obtain CNC microchips.

[0039] In this step, considering that the CNC film is fragile and the assembled structure is extremely vulnerable to external interference, the process of introducing a polymer to improve its flexibility will cause damage to the CNC structure. The present invention proposes to first fix the CNC structure (assemble the CNC into a film), and then encapsulate it with epoxy resin. For the convenience of encapsulation, the CNC is cracked into micron-sized fragments. Moreover, the shape, microstructure, color and position of the formed CNC microchips in the film are relatively special. When used as an anti-counterfeiting label, its anti-counterfeiting ability can be greatly enhanced.

[0040] (8) Add the CNC micro - slices prepared according to the above steps into 0.1 - 10 ml of resin solution, stir well to mix, and remove air bubbles by ultrasonic treatment to obtain a mixed system; uniformly coat it on the SiO 2 photonic crystal film by spin - coating method, and obtain a resin - encapsulated SiO 2 / CNC composite coating after drying. Among them, the spin - coating speed is 1500 - 3000 rpm, and the drying temperature is 20 - 80 °C.

[0041] In this process, the resin will penetrate into the gaps of the SiO 2 photonic crystal film. The CNC micro - slices are larger in size and will stay above the SiO 2 coating and be encapsulated by the resin. The encapsulation process depends on the adhesiveness and physical coating ability of the resin, and the SiO 2 microspheres and CNC micro - slices are fixed in the cured resin matrix.

[0042] The resin is one or more of phenolic resin, acrylic resin, phthalonitrile resin, epoxy resin, polyester resin; further, in the same composite film, the resin materials in the upper and lower films are consistent.

[0043] In the present invention, SiO 2 and CNC are respectively selected as the inorganic and organic nanoparticle assembly units, and a multi - optical - property composite material with easy recognition and high concealment is prepared by using their unique optical properties. However, the compatibility between the above two is poor. If directly assembled, the ordered structure of the SiO 2 photonic crystal and the nematic structure of CNC will affect and destroy each other. The method of the present invention first prepares the SiO 2 photonic crystal by spraying method, and its ordered structure is maintained after drying. Separately, CNC is assembled into a photonic crystal by evaporation - induced assembly, and then it is broken down into micron - sized photonic micro - slices by repeated rolling. At this time, its chiral nematic structure will no longer be destroyed. Add the CNC photonic micro - slices into the epoxy resin a and b glue mixture, stir well to mix, and uniformly coat it on the SiO 2 photonic crystal layer by spin - coating method, and obtain a resin - encapsulated SiO 2 / CNC composite coating after drying. Therefore, by using this method, the inherent ordered structures of the two photonic crystals can be maintained, so that different optical effects can be presented under different optical environments.

[0044] The second aspect of the present invention discloses a SiO 2 / CNC multi - optical - feature composite film prepared by the above preparation method. The film includes two layers stacked up and down. The lower film is SiO 2Photonic crystal thin film, the upper thin film is a CNC photonic microchip thin film; through resin encapsulation, the toughness of the thin film can be enhanced, and the mechanical properties of the thin film can be improved. For this composite thin film, the bright structural color of the CNC microchips can be observed under both natural light and polarized light, while the CNC structural color is hidden under a point light source, and only the gorgeous iridescent effect of SiO 2 can be seen, which has multiple optical characteristics and can be applied to multiple anti-counterfeiting. In addition, the thin film has excellent mechanical properties, which is beneficial to practical applications. The CNC microchip has circular dichroism and fingerprint texture structure and characteristics, and the multiple optical characteristic composite thin film is arranged in a layered structure and prepared and stacked into a chiral nematic structure.

[0045] The following is further described in combination with specific embodiments.

[0046] Example 1 (1) Regarding the specific preparation method and steps of nano-silica, the same as the patent "A Photochromic Coating and Its Preparation Method" (ZL 202110224660.8).

[0047] (2) Prepare the prepared SiO 2 into a 0.3 wt% anhydrous ethanol solution.

[0048] (3) Clean the experimental substrate glass sheet and dry it in an oven, and perform oxygen plasma treatment for 2 min.

[0049] (4) Prepare the SiO 2 photonic crystal by drop coating: Drop 1 μL of the SiO 2 0.3 wt% ethanol dispersion on the experimental substrate treated in (3), and wait for it to dry to obtain the assembled SiO 2 photonic crystal.

[0050] (6) Use a pipette gun to add 1 ml of resin and drop it on the center position of the substrate with a SiO 2 coating, and spin coat it at a speed of 2000 rpm for 20 s. After the spin coating is completed, place it in an oven at 50 °C and dry it thoroughly.

[0051] (7) Pour the 2 wt% CNC aqueous dispersion into a polystyrene petri dish, and perform evaporation-induced self-assembly at 50 °C to obtain a CNC photonic thin film, which is rolled into irregular fragments.

[0052] (8) Add the CNC microchips to the resin, and uniformly coat the above spin coating method on the SiO 2 photonic crystal layer at a speed of 2000 rpm, and obtain a resin-encapsulated SiO 2 / CNC composite coating after drying at 50 °C.

[0053] Figure 1is the SiO assembled in this embodiment 2 Photonic crystal under a black background. As can be seen from the figure, the surface flatness of the photonic crystal obtained without oxygen plasma treatment is insufficient, and the agglomeration phenomenon is serious. Due to the action of surface tension, SiO 2 particles agglomerate together. After oxygen plasma treatment, the contact angle of the solution surface decreases, which is more conducive to spreading, so the uniformity increases. Example 2 (1) Regarding the specific preparation method and steps of nano-silica, refer to the patent "A Photochromic Coating and Its Preparation Method" (ZL 202110224660.8).

[0054] (2) Prepare the prepared SiO 2 into a 0.35 wt% anhydrous ethanol solution.

[0055] (3) Clean the experimental substrate glass slide and dry it in an oven, and perform oxygen plasma treatment for 2 min.

[0056] (4) Prepare SiO 2 photonic crystal by drop coating method: Drop 1 μL of SiO 2 0.35wt% ethanol dispersion on the experimental substrate treated in (3), and wait for it to dry to obtain the assembled SiO 2 photonic crystal.

[0057] (6) Use a pipette gun to add 1 ml of resin and drop it at the center position of the substrate with a SiO 2 coating, spin coat at a speed of 2000 rpm for 20 s, and place it in an oven at 50 °C to dry thoroughly after spin coating.

[0058] (7) Pour 2 wt% CNC aqueous dispersion into a polystyrene petri dish, and obtain a CNC photonic film by evaporation-induced self-assembly at 50 °C, and roll it into irregular fragments.

[0059] (8) Add CNC microchips to the resin, and uniformly coat the above spin coating method on the SiO 2 photonic crystal layer at a speed of 2000 rpm, and obtain a resin-encapsulated SiO 2 / CNC composite coating after drying at 50 °C.

[0060] Example 3 (1) Regarding the specific preparation method and steps of nano-silica, refer to the patent "A Photochromic Coating and Its Preparation Method" (ZL 202110224660.8).

[0061] (2) Prepare the prepared SiO 2 into an anhydrous ethanol solution with a mass fraction of 20 wt %.

[0062] (3) Clean the experimental substrate glass slide, dry it in an oven, and perform oxygen plasma treatment for 3 min.

[0063] (4) Preparation of SiO 2 Photonic crystal: Drop 1 μL of 20 wt% SiO 2 ethanol dispersion on the experimental substrate treated in (3), and wait for it to dry to obtain the assembled SiO 2 photonic crystal.

[0064] (6) Use a pipette to measure 1 ml of resin and drop it at the center of the substrate with a SiO 2 coating, spin-coat at a speed of 2000 rpm for 20 s, and place it in an oven at 50 °C to dry thoroughly after spin-coating.

[0065] (7) Pour 2 wt% CNC aqueous dispersion into a polystyrene petri dish, and obtain a CNC photonic film by evaporation-induced self-assembly at 50 °C, and roll it into irregular fragments.

[0066] (8) Add the CNC microchips to the resin, and uniformly coat the above spin-coating method on the SiO 2 photonic crystal layer at a speed of 2000 rpm, and obtain a resin-encapsulated SiO 2 / CNC composite coating after drying at 50 °C.

[0067] Example 4 (1) Regarding the specific preparation method and steps of nano-silica, refer to the patent "A Photochromic Coating and Its Preparation Method" (ZL 202110224660.8).

[0068] (2) Prepare the prepared SiO 2 into an absolute ethanol solution with a mass fraction of 0.3 wt%.

[0069] (3) Clean the experimental substrate PET, dry it in an oven, and perform oxygen plasma treatment for 2 min.

[0070] (4) Preparation of SiO 2 Photonic crystal: Drop 1 μL of 0.3 wt% SiO 2 ethanol dispersion on the experimental substrate treated in (3), and wait for it to dry to obtain the assembled SiO 2 photonic crystal.

[0071] (6) Use a pipette to measure 1 ml of resin and drop it on the surface with SiO 2At the center position of the coated substrate, spin-coat for 20 s at a speed of 2000 rpm, and after the spin-coating is completed, place it in an oven at 50 °C for sufficient drying.

[0072] (7) Pour the 2 wt% CNC aqueous dispersion into a polystyrene petri dish, and obtain a CNC photonic film by evaporation-induced self-assembly at 50 °C, and roll it into irregular fragments.

[0073] (8) Add the CNC microchips to the resin, and uniformly coat the above spin-coating method on the SiO 2 photonic crystal layer at a speed of 2000 rpm, and obtain a resin-encapsulated SiO 2 / CNC composite coating after drying at 50 °C.

[0074] Figure 2 This is a photograph of the SiO 2 photonic crystal assembled on PET in this example against a black background. It can be seen from the figure that the surface flatness of the photonic crystal obtained without oxygen plasma treatment is insufficient and the agglomeration phenomenon is serious. This is due to the action of surface tension, and the SiO 2 particles agglomerate together. Compared with the glass substrate, the structural uniformity of the photonic crystal assembled on the PET substrate is poor. This is because the contact angles of different substrates treated for the same time are different, and the contact angle of the PET substrate is slightly larger, so the spreading effect is not good. After oxygen plasma treatment, the surface contact angle of the solution decreases, which is more conducive to spreading, so the uniformity increases. Example 5 (1) Regarding the specific preparation method and steps of nano-silica, refer to the patent "A Photochromic Coating and Its Preparation Method" (ZL 202110224660.8).

[0075] (2) Prepare the SiO 2 into an absolute ethanol solution with a mass fraction of 0.35 wt%.

[0076] (3) Clean the experimental substrate PET and dry it in an oven, and perform oxygen plasma treatment for 2 min.

[0077] (4) Prepare the SiO 2 photonic crystal by drop coating: Drop 1 μL of the 0.35 wt% SiO 2 ethanol dispersion on the experimental substrate treated in (3), and wait for it to dry to obtain the assembled SiO 2 photonic crystal.

[0078] (6) Use a pipette to draw 1 ml of resin and drop it at the center position of the substrate with a SiO 2 coating, spin-coat for 20 s at a speed of 2000 rpm, and after the spin-coating is completed, place it in an oven at 50 °C for sufficient drying.

[0079] (7) Pour 2 wt% of the CNC aqueous dispersion into a polystyrene Petri dish, and obtain a CNC photonic film by evaporation-induced self-assembly at 50 °C, and roll it into irregular fragments.

[0080] (8) Add the CNC microchips to the resin, and uniformly coat the above-mentioned spin coating method on the SiO 2 photonic crystal layer at a rotation speed of 2000 rpm, and obtain a resin-encapsulated SiO 2 / CNC composite coating after drying at 50 °C.

[0081] Example 6 (1) Regarding the specific preparation method and steps of nano-silica, refer to the patent "A Photochromic Coating and Its Preparation Method" (ZL 202110224660.8).

[0082] (2) Prepare the prepared SiO 2 into an absolute ethanol solution with a mass fraction of 0.3 wt%.

[0083] (3) Clean the experimental substrate glass slide, dry it in an oven, and perform oxygen plasma treatment for 2 min.

[0084] (4) Prepare the SiO 2 photonic crystal by drop coating: Drop 1 μL of 0.3 wt% SiO 2 ethanol dispersion on the experimental substrate treated in (3), and wait for it to dry to obtain the assembled SiO 2 photonic crystal.

[0085] (6) Use a pipette to draw 1 ml of resin and drop it at the center position of the substrate with a SiO 2 coating, spin coat at a rotation speed of 2000 rpm for 20 s, and place it in an oven at 50 °C for sufficient drying after the spin coating is completed.

[0086] (7) Pour 2% of the CNC aqueous dispersion into a polystyrene Petri dish, and obtain a CNC photonic film by evaporation-induced self-assembly at 50 °C, and roll it into irregular fragments.

[0087] (8) Add the CNC microchips to the resin, and uniformly coat the above-mentioned spin coating method on the SiO 2 photonic crystal layer at a rotation speed of 2000 rpm, and obtain a resin-encapsulated SiO 2 / CNC composite coating after drying at 50 °C.

[0088] Figure 3 This is a photo of the SiO 2 photonic crystal coating assembled on a glass substrate in this example. As can be seen from the figure, the photonic crystal coating has an iridescent effect under a point light source.

[0089] Example 7 (1)Regarding the specific preparation method and steps of nano-silica, refer to the patent "A Photochromic Coating and Its Preparation Method" (ZL 202110224660.8).

[0090] (2)Prepare the prepared SiO 2 into an absolute ethanol solution with a mass fraction of 0.6 wt%.

[0091] (3)Clean the experimental substrate glass slide, dry it in an oven, and perform oxygen plasma treatment for 2 min.

[0092] (4)Prepare SiO 2 photonic crystal by drop coating: Drop 1 μL of SiO 2 ethanol dispersion with a mass fraction of 0.6 wt% on the experimental substrate treated in (3), and wait for it to dry to obtain the assembled SiO 2 photonic crystal.

[0093] (6)Use a pipette to add 1 ml of resin and drop it at the center position of the substrate with a SiO 2 coating, spin coat at a speed of 2000 rpm for 20 s, and place it in an oven at 50 °C to dry thoroughly after spin coating.

[0094] (7)Pour 2% CNC aqueous dispersion into a polystyrene petri dish, and obtain a CNC photonic film by evaporation-induced self-assembly at 50 °C, and roll it into irregular fragments.

[0095] (8)Add the CNC microchips to the resin, and uniformly coat the above spin coating method on the SiO 2 photonic crystal layer at a speed of 2000 rpm, and obtain a resin-encapsulated SiO 2 / CNC composite coating after drying at 50 °C.

[0096] Figure 4 This is a photo of the SiO 2 photonic crystal coating assembled on a glass substrate in this example. As can be seen from the figure, as the concentration of SiO 2 increases, the iridescent effect enhances.

[0097] Example 8 (1)Regarding the specific preparation method and steps of nano-silica, refer to the patent "A Photochromic Coating and Its Preparation Method" (ZL 202110224660.8).

[0098] (2)Prepare the prepared SiO 2 into a 0.3 wt% absolute ethanol solution.

[0099] (3) Clean the experimental substrate glass sheet, dry it in an oven, and treat it with oxygen plasma for 2 min.

[0100] (4) Preparation of SiO by drop coating 2 Photonic crystal: 1 μL SiO was drop-coated on the experimental substrate treated in (3). 2 0.3wt% ethanol dispersion, wait for it to dry, and obtain the assembled SiO 2 Photonic crystal.

[0101] (6) Use a pipette to drop 1 ml of resin onto the surface of the SiO 2 The coating was applied to the center of the substrate at a speed of 2000 rpm for 20 s and then placed in a 50 °C oven to fully dry.

[0102] (7) A 2% CNC aqueous dispersion was poured into a polystyrene petri dish and evaporated at 50 °C to induce self-assembly to obtain a CNC photonic film, which was then rolled into irregular fragments.

[0103] (8) Add the CNC microchips to the resin and evenly coat the SiO2 with the above spin coating method at a speed of 2000 rpm. 2 The photonic crystal layer was dried at 50°C to obtain a resin-encapsulated SiO 2 / CNC composite coating.

[0104] Figure 5 The SiO2 assembled on the glass substrate in this embodiment 2 Optical photograph of photonic crystal coating after resin coating. As can be seen from the figure, the transparency of the coating is significantly improved, making the background pattern below clearly visible and the iridescence effect more brilliant.

[0105] Example 9 (1) The specific preparation method and steps of nano-silicon dioxide are the same as those in the patent “A photo-variable coating and its preparation method” (ZL 202110224660.8).

[0106] (2) Prepared SiO 2 Prepared into 0.3 wt% anhydrous ethanol solution.

[0107] (3) Clean the experimental substrate glass sheet, dry it in an oven, and treat it with oxygen plasma for 2 minutes.

[0108] (4) Preparation of SiO by spraying 2 Photonic crystal: Spray 1 mL SiO onto the experimental substrate treated in (3). 2 Ethanol dispersion (0.3 wt%), after drying, the assembled SiO 2 Photonic crystal.

[0109] (6) Use a pipette to add 1 ml of resin and drop it onto the center of the substrate with an SiO 2 coating, spin-coat for 20 s at a speed of 2000 rpm, and place it in an oven at 50 °C for sufficient drying after spin-coating.

[0110] (7) Pour the 2 wt% CNC aqueous dispersion into a polystyrene petri dish, and obtain a CNC photonic film by evaporation-induced self-assembly at 50 °C, and roll it into irregular fragments.

[0111] (8) Add the CNC microchips to the resin, and uniformly coat the above spin-coating method on the SiO 2 photonic crystal layer at a speed of 2000 rpm, and obtain an SiO 2 / CNC composite coating after drying at 50 °C.

[0112] Figure 6 is a photograph of the SiO 2 photonic crystal coating assembled on a glass substrate in this example. As can be seen from the figure, the coating prepared by the spraying method is more uniform than that by the drop-coating method. However, when the spraying amount is low, the obtained photonic crystal layer has a poor iridescent effect under a point light source.

[0113] Example 10 (1) Regarding the specific preparation method and steps of nano-silica, refer to the patent "A Photochromic Coating and Its Preparation Method" (ZL 202110224660.8).

[0114] (2) Prepare the SiO 2 into a 0.3 wt% anhydrous ethanol solution.

[0115] (3) Clean the experimental substrate glass slides, dry them in an oven, and perform oxygen plasma treatment for 2 min.

[0116] (4) Prepare SiO 2 photonic crystals by spraying method: Spray 2 mL of SiO 2 ethanol dispersion (0.3 wt%) on the experimental substrate treated in (3), and wait for it to dry to obtain the assembled SiO 2 photonic crystals.

[0117] (6) Use a pipette to add 1 ml of resin and drop it onto the center of the substrate with an SiO 2 coating, spin-coat for 20 s at a speed of 2000 rpm, and place it in an oven at 50 °C for sufficient drying after spin-coating.

[0118] (7) Pour the 2% CNC aqueous dispersion into a polystyrene petri dish, and obtain a CNC photonic film by evaporation-induced self-assembly at 50 °C, and roll it into irregular fragments.

[0119] (8) Add the CNC microchips to the resin and uniformly coat the above spin coating method on SiO 2 photonic crystal layer at a rotational speed of 2000 rpm. After drying at 50 °C, a resin-encapsulated SiO 2 / CNC composite coating is obtained.

[0120] Example 11 (1) Regarding the specific preparation method and steps of nano-silica, refer to the patent "A Photochromic Coating and Its Preparation Method" (ZL 202110224660.8).

[0121] (2) Prepare the SiO 2 into a 0.3 wt% anhydrous ethanol solution.

[0122] (3) Clean the experimental substrate glass slide, dry it in an oven, and perform oxygen plasma treatment for 2 min.

[0123] (4) Prepare the SiO 2 photonic crystal by spraying method: Spray 2 mL of SiO 2 ethanol dispersion (0.3 wt%) on the experimental substrate treated in (3). After drying, an assembled SiO 2 photonic crystal is obtained.

[0124] (6) Use a pipette to add 1 ml of resin and drop it at the center position of the substrate with a SiO 2 coating. Spin coat at a rotational speed of 2000 rpm for 20 s, and after the spin coating is completed, place it in an oven at 50 °C for sufficient drying.

[0125] (7) Pour the 2 wt% CNC aqueous dispersion into a polystyrene petri dish and perform evaporation-induced self-assembly at 50 °C to obtain a CNC photonic film, which is rolled into irregular fragments.

[0126] (8) Add the CNC microchips to the resin and uniformly coat the above spin coating method on SiO 2 photonic crystal layer at a rotational speed of 2000 rpm. After drying at 50 °C, a resin-encapsulated SiO 2 / CNC composite coating is obtained.

[0127] Figure 7 is a photo of the SiO 2 photonic crystal coating assembled on a glass substrate in this example. It can be seen from the figure that the photonic crystal layer obtained by the spraying method shows a very strong iridescent effect after being encapsulated with resin. And the surface uniformity of the coating obtained after resin encapsulation is higher.

[0128] Example 12 (1)Regarding the specific preparation method and steps of nano-silica, refer to the patent "A Photochromic Coating and Its Preparation Method" (ZL 202110224660.8).

[0129] (2)The prepared SiO 2 is configured into a 0.3 wt% anhydrous ethanol solution.

[0130] (3)Clean the experimental substrate glass slide, dry it in an oven, and perform oxygen plasma treatment for 2 min.

[0131] (4)Prepare SiO 2 photonic crystal by spraying method: Spray 2 mL of SiO 2 ethanol dispersion (0.3 wt%) on the experimental substrate treated in (3), and wait for it to dry to obtain the assembled SiO 2 photonic crystal.

[0132] (6)Use a pipette to add 1 ml of resin and drop it at the center position of the substrate with a SiO 2 coating, spin-coat at a speed of 2000 rpm for 20 s, and then place it in an oven at 50 °C to dry thoroughly after spin-coating.

[0133] (7)Pour 2% CNC aqueous dispersion into a polystyrene petri dish, and obtain a CNC photonic film by evaporation-induced self-assembly at 50 °C, and roll it into irregular fragments.

[0134] (8)Add CNC microchips to the resin, and uniformly coat the above spin-coating method on the SiO 2 photonic crystal layer at a speed of 2000 rpm, and obtain a resin-encapsulated SiO 2 / CNC composite coating after drying at 50 °C.

[0135] Figure 8 This is the patterned application of the SiO 2 / CNC coating on the substrate. As can be seen from the figure, the CNC structural color can be observed on the black background. Under the point light source, the CNC microchips are hidden, and only the iridescent effect of SiO 2 is presented.

[0136] Example 13 In this example, the spin-coating speed of the first resin is 1500 rpm, and the spin-coating time is 80 s. The other parts not involved are the same as in Example 1.

[0137] Example 14 In this example, the spin-coating speed of the first resin is 3000 rpm, and the spin-coating time is 1 s. The other parts not involved are the same as in Example 1.

[0138] Example 15 In this embodiment, the mass fraction of the CNC aqueous dispersion is 20%, and the other parts not involved are the same as those in Embodiment 1.

[0139] Embodiment 16 In this embodiment, the mass fraction of the CNC aqueous dispersion is 15%, and the other parts not involved are the same as those in Embodiment 1.

[0140] Embodiment 17 In this embodiment, in step (7), the evaporation temperature of the CNC aqueous dispersion is 20°C, and the other parts not involved are the same as those in Embodiment 1.

[0141] Embodiment 18 In this embodiment, in step (7), the evaporation temperature of the CNC aqueous dispersion is 20°C, and the other parts not involved are the same as those in Embodiment 1.

[0142] Embodiment 19 In this embodiment, in step (8), the spin coating speed is 1500 rpm and the drying temperature is 20°C, and the other parts not involved are the same as those in Embodiment 1.

[0143] Embodiment 20 In this embodiment, in step (8), the spin coating speed is 3000 rpm and the drying temperature is 80°C, and the other parts not involved are the same as those in Embodiment 1.

[0144] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a SiO2 / CNC composite film with multiple optical characteristics by resin encapsulation, characterized in that: The following steps are involved: Step 1, coating a dispersion of silica microspheres in anhydrous ethanol on a substrate, allowing the silica microspheres to self-assemble to obtain SiO2 photonic crystals; Step 2, spin coating the first resin on the SiO2 photonic crystal, and drying after spin coating to obtain a SiO2 photonic crystal film; Step 3, evaporation induces CNC aqueous dispersion to self-assemble to obtain CNC photonic film, and the CNC photonic film is crushed to obtain micron-sized fragments, which are CNC micro-sheets; Step 4, adding CNC microchips into the second resin, stirring to obtain a mixed system, spin coating the mixed system on the SiO2 photonic crystal film, and preparing a CNC photonic microchip film on the SiO2 photonic crystal film after drying to obtain a SiO2 / CNC multiple optical feature composite film.

2. The method for preparing a SiO2 / CNC composite film with multiple optical characteristics by resin encapsulation according to claim 1, characterized in that: In step 1, the particle size of the silica microspheres in the anhydrous ethanol dispersion of silica microspheres is normally distributed; and the mass fraction of the anhydrous ethanol dispersion of silica microspheres is 0.3-20%.

3. The method for preparing a SiO2 / CNC composite film with multiple optical characteristics by resin encapsulation according to claim 1, characterized in that: The specific process of step 1 is to coat the anhydrous ethanol dispersion of silica microspheres on the substrate by drop coating, spray coating or spin coating, and obtain the SiO2 photonic crystal film after drying.

4. The method for preparing a SiO2 / CNC composite film with multiple optical characteristics by resin encapsulation according to claim 1, characterized in that: In step 2, the spin coating speed of the first resin is 1500-3000 rpm, and the spin coating time is 1-80s.

5. The method for preparing a SiO2 / CNC composite film with multiple optical characteristics by resin encapsulation according to claim 1, characterized in that: The first resin and the second resin are one or more of phenolic resin, acrylic resin, phthalonitrile resin, epoxy resin, and polyester resin.

6. The method for preparing a SiO2 / CNC composite film with multiple optical characteristics by resin encapsulation according to claim 1, characterized in that: In step 3, the mass fraction of the CNC aqueous dispersion is 2-20%.

7. The method for preparing a SiO2 / CNC composite film with multiple optical characteristics by resin encapsulation according to claim 1, characterized in that: In step 3, the evaporation temperature is 20-80°C.

8. The method for preparing a SiO2 / CNC composite film with multiple optical characteristics by resin encapsulation according to claim 1, characterized in that: In step 4, the spin coating speed is 1500-3000 rpm.

9. The method for preparing a SiO2 / CNC composite film with multiple optical characteristics by resin encapsulation according to claim 1, characterized in that: In step 4, the drying temperature is 20-80°C.

10. A SiO2 / CNC composite film with multiple optical characteristics prepared by the resin encapsulation preparation method according to any one of claims 1 to 9, characterized in that: It includes a lower SiO2 photonic crystal film and an upper CNC photonic microchip film.

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