A flexible optical variable film with light-induced angle-dependent color change and its preparation method

Abstract

The present invention relates to a flexible optical variable thin film with light-induced angle-dependent color change and a preparation method thereof. The base film is selected from one of biaxially oriented polyester film (BOPET), biaxially oriented polypropylene film (BOPP), OPP and nylon (PA) film. By using suitable equipment, processes and materials, an adhesive layer, a reflective layer, a refractive layer and a protective layer are plated and coated based on metals Cr\AL and polymers. It is fully considered that the finished product can still maintain flexibility after the drying and forming of each film layer, and light can propagate between different film layers. As a result of multiple reflections and refractions interacting with each other, an interference phenomenon of "two-color effect" of light occurs, resulting in a light-induced angle-dependent color change effect, and endowing the thin film with different bright lights and colors from multiple perspectives.

Description

Technical Field

[0001] The present invention belongs to the fields of optics and optical medium materials. Specifically, it relates to a flexible optical variable film with light-induced angle-dependent color change and a preparation method thereof. Background Art

[0002] In people's current life, due to the good performance of optical thin films, they can be applied not only in related optical fields but also in various fields. Optical thin films add splendor to life in civilian applications such as computer and mobile phone screens, the thin films on the outer layer of glasses, and lighting optical thin films. In agricultural production, they are used as sunshade and energy-saving curtain films, etc. Their applications in industrial and even national defense fields, such as in optical devices and optical communications, are too numerous to enumerate. With the rapid development of optical thin films, their correlation with other disciplines has increased, and they can be applied to more and more fields.

[0003] Optical variable films are relatively advanced technical products among optical thin film products; for optical medium material film systems, the colors generated by light transmission and reflection due to layered interference are mainly adjusted by changing the thin film stack structure to make the spectral reflection peak located in the direction providing the required color change and shift towards the corresponding direction. For the transmission and reflection of the propagating light beam through the interfaces of different layered media in the thin film, a layered interference film system shows angle-dependent color change (angle-dependent color; when observed from different angles under light, the product presents different colors), showing different color hues. The color change range and saturation on the thin film are determined by the thickness, composition, and particle size of the layered media on the film and their refractive indices for light. Optical variable films are formed by stacking multiple layers using different materials, processes, and equipment. The thin film can be prepared by comprehensively using various methods such as sputtering, vacuum vapor deposition, chemical vapor deposition, spraying, and sol-gel impregnation stacking.

[0004] The general layered structure on an optical variable film is: substrate film - adhesive layer - reflective layer - refractive medium layer - absorption layer; the substrate and adhesive layer do not affect the optical properties of the thin film, and each of the reflective layer, refractive medium layer, and absorption layer affects the reflectivity, color, and saturation of the optical properties of the thin film respectively.

[0005] Currently, optical variable films are mainly prepared on the surfaces of different rigid substrates (such as steel, glass, plastic, ceramic, etc.), expanding the new uses of optical thin films; light-induced angle-dependent color change has been applied in fields such as decoration, ink, and anti-counterfeiting due to its unique properties. However, flexible optical variable films with similar characteristics prepared using 'flexible polymer films' as the substrate are rarely seen.

[0006] The adhesive layer bonds the substrate and the film layer to ensure good bonding at the adhesion interface and maintain strength. It can be formed by depositing a very thin layer of a metal with a relatively large atomic volume as the adhesive layer, forming a structure similar to a network or islands, which can promote the tightness of the film layer using it as the connection layer. Or a cross-linked adhesive solution is coated on the surface of the substrate film as the adhesive layer. The adhesive layer is very important for the final result of the optical variable film. If the adhesiveness is not ideal and firm, it will directly cause the film layer to fall off.

[0007] The reflective layer is necessary to create an opaque coating above the substrate, which has a stable and uniform visual color, reducing the dependence of the color impression of the coating prepared above on the substrate material. A single metal layer with high brightness is deposited on the adhesive layer to obtain a high reflectivity. There are many coating methods for the reflective layer, such as electroplating and vacuum coating. The most widely used method is mainly achieved by thermal evaporation coating in vacuum coating. This method has a high deposition rate, a large deposition area, and high production efficiency. In addition, the equipment and operation are relatively simple. However, the disadvantages of the vacuum evaporation coating method are also very prominent. For the thin film prepared by this method, since the deposited thin film adopts an island growth mode, the migration ability of monomers on the substrate surface has a direct impact on the structure of the thin film. The aggregation density is small, the refractive index is low; it is easy to adsorb residual gases and water vapor, and the timeliness is poor; if the surface and interface are not flat, the surface scattering is large; the stress is high, the hardness is low, the adhesion is small, and the firmness is poor, etc.

[0008] The refractive medium layer can also be formed by using metals and transition metal oxides to form a simple or composite nanoparticle system in the dielectric layer, so that the light of the reflective layer changes the light propagation direction through scattering on its particles, and the lateral scattered light is emitted. More different colors can be obtained within a certain thickness range. The particle material can be inorganic or organic. Commonly used inorganic particles include silica, zinc oxide, titanium dioxide, zirconium oxide, alumina, zinc sulfide, barium sulfate, and their mixtures, etc. Commonly used organic particles include styrene polymers, acrylic polymers, silicone polymers, etc. The refractive medium layer can be stacked according to needs. The film material formed by the dielectric layer should not only have as high transparency as possible, but also be cured with the simple or composite nanoparticles in the layer through high temperature to form a stable system. The introduction of high temperature conditions will inevitably increase the difficulty of the application substrate and process conditions and limit the material selection range.

[0009] The refractive medium layer mostly uses the'sol-gel dipping method'. Compared with methods such as sputtering, chemical vapor deposition, and spraying, it can easily coat large-area substrates. The sol-gel method (a+gel) is a wet chemical reaction method with the advantages of simple operation process, easy reaction control, no need for vacuum equipment, uniform doping, controllable film thickness, strong adhesion to the substrate, easy doping at the atomic level, and can prepare thin films on large-area and complex-shaped substrates. The thin films prepared by the sol-gel method are more likely to form nano-porous structures, have high chemical activity, and are easy to form films. They are often used to prepare organic-inorganic composite films on the surface of plastics, and hard coatings with an inorganic coating on the outer surface and an organic coating in the middle can be obtained. Using the sol-gel method to make metal alkoxides and other organic polymers undergo co-condensation reactions has become one of the effective methods for preparing organic-inorganic hard coating materials. The main disadvantages are that hard materials need to be used as substrates, such as steel, glass, plastics, ceramics, etc., and the film needs to be cured at a high temperature (>400°C) to form. The thickness of the thin film made in one coating operation is small. The shrinkage rate of the film layer is relatively large during the treatment process, and the film layer is prone to uneven shrinkage. The thin film is easy to form a porous structure, resulting in defects such as cracks and bubbles. Process conditions such as solution concentration, pH value of the solution, viscosity, compatibility of dopants, drying process and heat treatment temperature, and the relative speed of film-forming reaction and solvent evaporation will have a great impact on film formation.

[0010] The absorption layer is a fully transparent protective layer, which must be realized by using a transparent coating agent by the coating method. It has a high light transmittance (Tave>95%) for visible light (λ = 380 - 780nm). Its transparency directly affects the final effect of the photochromic film. Moreover, it must be firmly bonded to the refractive medium layer. The adhesive has good compatibility with the adherend, has a certain softness, surface scratch resistance and wear resistance, and has high requirements for its quality and performance.

[0011] From the analysis of the defects and deficiencies existing in the production process of the above-mentioned existing photochromic film manufacturing methods, there is currently no relevant report on the preparation of flexible photochromic films with photochromic angle-dependent color change by the'sol-gel dipping method', that is, the characteristics are: a. The substrate uses a flexible polymer film'. b. The film can be cured at a low temperature. c. Maintain continuous color change due to photochromic angle-dependent color change. d. The surface of the photochromic film is highly transparent and wear-resistant'. Undoubtedly, it is the bottleneck encountered by photochromic films with similar characteristics prepared using 'flexible polymer films'; it has become the key and focus to overcome the problems and deficiencies existing in the prior art. Summary of the Invention

[0012] The purpose of the present invention is to provide a method for preparing a photochromic film with photochromic angle-dependent color change using a flexible polymer film as the substrate; the purpose of the present invention is achieved through the following scheme:

[0013] A flexible photochromic film with angle-dependent color change and its preparation method. The flexible photochromic film with angle-dependent color change includes a substrate film, an adhesive layer, a reflective layer, a refractive layer, and a protective layer arranged from the inside out;

[0014] The substrate film includes one of biaxially oriented polyester film (BOPET), biaxially oriented polypropylene film (BOPP), oriented polypropylene film OPP, and nylon film (PA);

[0015] The adhesive layer is a modified acrylic crosslinking adhesive, or a vacuum-deposited thermal evaporation cadmium or aluminum film;

[0016] The reflective layer is a vacuum-deposited thermal evaporation aluminum film;

[0017] The refractive layer is an organosilicon oligomer-modified acrylate resin doped with nano-scale aluminum flakes;

[0018] The protective layer is an organosilicon emulsion-type adhesive solution containing long-chain groups;

[0019] The adhesive layer and reflective layer of the photochromic film are prepared by vacuum-deposited thermal evaporation coating method in sequence, and the refractive layer and protective layer of the photochromic film are prepared by solution coating method to obtain a flexible photochromic film with angle-dependent color change.

[0020] One of biaxially oriented polyester film (BOPET), biaxially oriented polypropylene film (BOPP), oriented polypropylene film (OPP), and nylon film (PA) is selected as the substrate film, and the thickness of the substrate film is 6μm - 36μm.

[0021] The selected acrylic crosslinking adhesive modified with polyol is coated on the selected substrate film to form an adhesive layer. The preparation process of the acrylic crosslinking adhesive modified with polyol is as follows:

[0022] (1) Raw material ratio, by mass fraction, Component A: glycerol: 12.8%, sodium hypophosphite: 1.16%, polyvinyl alcohol: 0.4%, emulsifier OP-10: 0.06%, deionized water H 2 O: 27%; Component B: acrylic acid: 32%, ammonium persulfate: 0.25%, deionized water H 2 O: 12%; The ratio of Component A to Component B is 1:1.5;

[0023] (2) Add component A into the reaction kettle at room temperature; stir and mix, and start heating under stirring. When the temperature is greater than 85 °C, start dropping component B which has been stirred and mixed evenly beforehand; at this time, the reaction temperature shall not be greater than 90 °C. Control the dropping speed of the dropping liquid according to the reaction temperature, and the dropping time is about 3.5 - 4.0 hours. Raise the temperature to 95 °C within half an hour after dropping, and keep the temperature at 95 °C for 2 hours and then stop the reaction to obtain the polyol-modified acrylic crosslinking adhesive; the viscosity of the obtained polyol-modified acrylic crosslinking adhesive is 0.05 - 0.07 Pa·s, the solid content is 45 - 50%, and the film curing temperature is 90 - 140 °C;

[0024] (3) Use a coater to measure according to the coating film thickness of 6 - 8 g / m 2 and evenly coat the polyol-modified acrylic crosslinking adhesive solution on the surface of the substrate film, and dry it through a drying air duct device at a temperature < 140 °C in the drying section to form an adhesive layer.

[0025] On the substrate film, use vacuum thermal evaporation method with metal Cr and Al wires with a purity of > 99.0%, and deposit a cadmium or aluminum thin film layer with a thickness of about 1 - 5 nm under the condition of a vacuum degree of 0.9 - 0.2 Pa to become an adhesive layer.

[0026] On the adhesive layer that has been formed on the substrate film, use vacuum thermal evaporation method to deposit an aluminum thin film with a thickness less than 100 nm to form an opaque reflective layer.

[0027] The refractive layer is prepared by using an organosilicon oligomer to modify acrylate resin:

[0028] (1) Raw material ratio, by mass:

[0029] Component C: The ratio of phenyltriethoxysilane to dimethyldiethoxysilane is 1:2.5, the content is 85 - 88%, and deionized water is 120%;

[0030] Component D: The ratio of acrylic acid, β-hydroxyethyl methacrylate, and butyl acrylate is 7:1:2, the content is 8 - 15%; initiator: azobisisobutyronitrile, 0.3 - 0.5%, solvent: a small amount of toluene;

[0031] Component E: Composite emulsifier: The ratio of span + peregal (span + O - 20, OP - 10) is (1 + 2):7, the content is 3 - 4%; a small amount of deionized water;

[0032] Among them, the ratio of C:D:E is 1:2:0.3;

[0033] (2) Preparation of silicone oligomer; in a reaction kettle, add component C according to a ratio of 1:0.3; silicone monomer and component E composite emulsifier, and dropwise add concentrated hydrochloric acid until the pH of the solution is 1-3. Stir and heat up to 50 °C, dropwise add deionized water. After the addition is completed, keep the temperature constant for 40 min, then continue to heat up to 75 °C and keep the temperature constant for reaction for 5 h. Then dropwise add 10% ammonia water to adjust the reaction solution to neutral, and carry out vacuum distillation to obtain the product silicone oligomer. Pour the product silicone oligomer into a dry and clean container, seal it and store it for later use;

[0034] (3) Preparation of silicone-modified acrylate resin; weigh the prepared silicone oligomer and pour it into the reaction kettle, add the solvent toluene so that the liquid level submerges the stirring paddle in the kettle. Pass nitrogen, start stirring, and heat up to 75 °C. Then, according to the raw material ratio, dropwise add component D; monomer and initiator mixture into the kettle. Finish the dropwise addition in about 1 h, react for about 1.5 h, cool down and discharge to obtain a silicone oligomer-modified acrylate resin to form a solution with a low viscosity of 0.05-0.07 Pa·s, which is the precursor of the dielectric layer;

[0035] (4) Doping of nano-aluminum flakes in the dielectric layer precursor; in the prepared polymer precursor solution of silicone oligomer-modified acrylate resin, uniformly and quantitatively incorporate nano-aluminum flakes with a particle size of 30-50 nm under stirring. The addition ratio is 0.5-1.2%, to achieve uniform doping and form a solution with doped nano-aluminum flakes and a low viscosity of 0.05-0.07 Pa·s.

[0036] Preferably, the mixed solution with low viscosity of doped nano-aluminum flakes is uniformly coated on the surface of the substrate film where the reflective layer has been formed by a coater, and dried at 100-150 °C through a drying air duct device to form a refractive layer.

[0037] Preferably, the preparation method of the protective layer is as follows:

[0038] (1) Raw material ratio: by mass fraction:

[0039] Component F: The ratio of methyltriethoxysilane, dimethyldiethoxysilane, and hexamethyldisiloxane (HMDSO) is 7:2.5:0.5, and the content ratio of component F is 96-97%; the catalyst is hydrochloric acid with a content of 0.8%, the solvent is 120 #L of solvent oil, and the content of deionized water is 120%;

[0040] Component G; The ratio of composite emulsifier AEO-3 + P-10 is 3:7, and the content is 3-4%, with a small amount of deionized water H 2 O;

[0041] (2) Preparation of organosilicon oligomer emulsion adhesive; in a reaction kettle, deionized water, concentrated hydrochloric acid, and 120#L solvent oil were added according to a certain ratio, and component F was added dropwise under rapid stirring; after the addition was completed, the mixture was heated under reflux for 6 h, cooled to below 40 °C, the water layer was removed, the organic layer was washed twice with 5% sodium carbonate solution, and then washed with deionized water until neutral. After drying with anhydrous calcium chloride, it was distilled under normal pressure to 150 °C to remove the solvent, and under the conditions of 180 °C and 133 Pa, it was distilled under reduced pressure to remove low-boiling substances. The obtained product was a colorless transparent viscous liquid, which was an organosilicon oligomer resin containing long-chain groups; then component G was mixed and stirred with a small amount of water to completely disperse the emulsifier in the water, and then the above-prepared organosilicon resin was added according to the formula, and stirring was continued until the system turned phase and increased in viscosity. The remaining water was slowly added, with the criterion that the system could be dispersed in time. After the addition of water was completed, stirring was continued for 30 min to obtain an organosilicon emulsion-type adhesive containing long-chain groups with a viscosity of about 0.05 - 0.07 Pa·s;

[0042] (3) Using a coater according to the coating film thickness; 4 - 6 g / m 2 Measurement, the organosilicon emulsion-type adhesive solution containing long-chain groups was evenly coated on the formed refraction and dielectric layer of the substrate film, and dried by a drying air duct device. The temperature in the drying section was <140 °C to form a light absorption layer protective layer, and a flexible photochromic film with photochromic color change with the angle was obtained.

[0043] Compared with the prior art, the beneficial effects of the present invention

[0044] 1. Compared with the existing sol-gel method for making photochromic films, the photochromic film made by the present invention is flexible, has a wide application range, meets the requirements of coating temperature, is resistant to damage and corrosion, has excellent alkali resistance, has a good surface shape, has good adhesion performance with the adhesive layer, can be coated evenly in a large area, and has the characteristics of relatively low price. And for the main materials of the adhesive layer, refraction layer, and light absorption layer protective layer, materials that are more flexible than the base film after drying and forming are selected (such as; polyol-modified acrylic crosslinking adhesive, organosilicon oligomer-modified acrylate resin, low-viscosity hydroxyl polysiloxane), which ensures the flexibility of the finished photochromic film. It provides a new basic material for expanding the application range of photochromic films in various fields.

[0045] 2. Compared with the existing sol-gel method for making photochromic films, during the production process of each process of the photochromic film made by the present invention, the temperature required for curing and forming the film dielectric layer in the whole process of preparing the photochromic film is <150 °C. It is much lower than the high temperature curing and forming >400 °C required by the sol-gel method for making films, which provides a great improvement space for the equipment, process optimization, production energy conservation, and cost reduction of the photochromic film production system.

[0046] 3. Use the vacuum thermal evaporation method to deposit an opaque high-reflection aluminum layer with a thickness of about 3-5 nm on the bonding layer. The reflectivity of light reaches 95%, which plays a very strong role in increasing the reflection of transmitted light from refraction and the dielectric layer. Aluminum is a metal with high light reflection performance second only to silver and has a low cost.

[0047] The adhesive coated on the bonding layer is a water-soluble liquid obtained by the carboxyl-polyol esterification cross-linking polymerization reaction of acrylic monomers with glycerol (glycerol), polyethylene glycol, etc. At a certain temperature, various active groups carried by the resin chain itself interact and cross-link, and self-cross-linking can be achieved at a higher temperature (such as 130-140 °C). The adhesion of the cross-linked coating film is enhanced. Due to the increase in polar groups on the macromolecular chain, the adsorption capacity for the substrate is improved.

[0048] 4. On the aluminum film reflection layer where the thin film has been prepared, the coated refractive and dielectric layer organosilicon oligomer-modified acrylate resin and the light absorption layer protective layer hydroxyl polysiloxane solution are both highly transparent after the film is cured, and the light transmittance reaches T%>98%. Light penetrates-reflects-refracts in the photochromic film to achieve better intensity and effect.

[0049] 5. Coat an organosilicon-modified acrylic resin prepared by copolymerization on the refractive layer. On the one hand, a copolymerization reaction occurs between the siloxane and acrylate molecules, grafting the organosilicon molecular chain onto the macromolecule of the acrylic resin in the form of chemical bonds for chemical modification. Introduced into the macromolecule of polyacrylate, these two polymers with poor compatibility are combined together by forming chemical bonds, thereby improving the compatibility between the two phases and inhibiting the surface migration of organosilicon molecules, achieving uniform dispersion of organosilicon and polyacrylate at the microscopic level. The film-forming substance combines the advantages of acrylate and organosilicon to form a film with good film-forming properties. The film is soft, transparent, has a large tensile strength, and a large elongation at break, achieving the effects of high flexibility and high transparency of the film.

[0050] 6. Uniformly and quantitatively incorporate nano-aluminum flakes into the polymer precursor solution of the formed refractive and dielectric layer, and use it to cause a high light refractive index in the layer after the dielectric layer is cured. Utilizing the symmetrical structure on both sides of the nano-aluminum flakes, no matter how the flakes are arranged in the dielectric layer, there is always a light-receiving surface on one side. Light changes its propagation direction through reflection and scattering on these aluminum flakes. The laterally scattered light shoots out, and the forward scattered light that cannot shoot out will continue to propagate towards the far end for the next scattering. Due to the result of this multiple reflection and refraction interaction, an interference phenomenon of the light "two-color effect" occurs, forming light with different glosses and different colors. Also, when the incident angle of light changes or the viewing angle changes, the gloss and chromaticity also change, presenting a color-changing effect of light-induced angle-dependent color, endowing the thin film with bright light and colors.

[0051] 7. The pH of the polymer precursor solution of the refractive layer is neutral, and there is no need to use organic or inorganic coating methods to modify the nano-aluminum flakes to improve the water resistance and corrosion resistance of the aluminum flakes. The diameter-to-thickness ratio of the nano-flaky aluminum powder is much larger than that of the traditional aluminum powder. Since the thickness of the coated refractive interlayer is generally uniform, the arrangement direction of the nano-aluminum flakes incorporated into the interlayer tends to be disorderly to generally flat during the gradual solidification of the interlayer sol, which can solve the problem of uneven dispersion. The refractive layer can change color according to different light needs by changing the thin film stacking structure to superimpose different layers, and dyeing the nano-flake aluminum incorporated therein into the required color to adjust the color and its change trajectory, so that the spectral reflection peak is located in the direction that provides the required color change and moves in the direction to which it belongs. It provides a large space for transformation for manufacturing diversified and differentiated products.

[0052] 8. The hydroxy polysiloxane solution used for coating the light absorption layer and protective layer has good overall film-forming properties and high transparency. After the coating is cured, a continuous, uniform, complete and integrated rubber-like elastic film will be formed on the surface of the film. It has anti-static, weather-resistant, wear-resistant and water-resistant properties. It will not produce obvious scratches when scratched by sharp tools or rubbed by metal, which plays a good protective role on the surface of the light-variable film. DETAILED DESCRIPTION

[0053] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples. The experimental methods in the following examples without specifying specific conditions are carried out according to conventional methods and conditions, or selected according to the product specifications.

[0054] Example 1

[0055] ①, Biaxially oriented polyester film (BOPET) is used as the base film. (Thickness of the film: 12μm). A cadmium layer with a thickness of about 1nm is plated on the base film by vacuum thermal evaporation method (vacuum degree 0.9pɑ) to form an adhesive layer. (The purity of the metal Cr and wire is >99.0%).

[0056] ②. Then, a cadmium bonding layer is formed on the substrate film by vacuum thermal evaporation with a vacuum degree of 0.2 pɑ, and an aluminum film with a thickness of about 100 nm is plated to form a high reflective layer with a reflectivity of T>98% (the purity of the metal and AL wire is>99.0%).

[0057] ③. Use silicone oligomer to modify acrylate resin to prepare refractive and dielectric layers;

[0058] a. Raw material ratio (mass fraction); Component A; [monophenyltriethoxysilane C 12 H 20 O 3 Si; dimethyldiethoxysilane DMDES / (ratio; 1; 2.5)]; 88%. Deionized water H 2O; 120%. Component B; [Acrylic acid (AA); 2-Hydroxyethyl methacrylate (HEMA); Butyl acrylate (BA) / (ratio; 7; 1; 2)]; 15%. Initiator; [2,2'-Azobis(2-methylpropionitrile) (ABIN)]; 0.5%. Solvent; [Toluene C 7 H 8 ; (appropriate amount). Component C; Composite emulsifier [Span + Peregal span + O-20, OP-10 / (ratio; 3; 7] 4%. Deionized water H 2 O; (appropriate amount). Component E; Incorporated with nano aluminum flakes [AL (silver) thickness; 50 nm, light reflectivity; >98.0%] 1.2%.

[0059] b. Preparation of organosilicon oligomer; In a reaction kettle (equipped with a stirrer, reflux condenser, and thermometer), add Component A organosilicon monomer, and dropwise add concentrated hydrochloric acid until the pH of the solution is between 1 and 3. While stirring, heat up to 50 °C, and dropwise add a quantitative amount of deionized water at a constant rate. React at 75 °C for 5 h, dropwise add 10% ammonia water to adjust the reaction solution to neutral, and perform vacuum distillation. Pour the product into a dry and clean container and store it sealed for later use.

[0060] c. Preparation of organosilicon-modified acrylate resin precursor; Pour the organosilicon oligomer prepared in item b into a reaction kettle (equipped with a stirrer, reflux condenser, and thermometer), add an appropriate amount of solvent toluene (the liquid level only needs to submerge the stirrer in the kettle), pass nitrogen, and stir and heat up to 75 °C. Then, dropwise add the mixed solution of Component B; monomer and initiator to the kettle, and finish dropping in about 1 h. React for about 1.5 h. Synthesize a solution with a viscosity of about 0.05 Pa·s as the precursor of the dielectric layer.

[0061] d. Doping of nano aluminum flakes in the polymer precursor; In a quantitative solution of organosilicon oligomer-modified acrylate resin polymer precursor, uniformly incorporate 1.2% of nano aluminum flakes under stirring to prepare a low-viscosity solution of doped nano aluminum flakes with a viscosity of 0.05 Pa·s.

[0062] e. On the formed high-reflection layer substrate film, use a coater (draw machine (MDO), in-line coater) to uniformly coat the prepared low-viscosity mixed solution d doped with nano aluminum flakes; at 8 g / m 2 (dry weight) on the formed high-reflection layer of the substrate film to form a refractive layer, and dry it through a drying air duct device (drying zone temperature; <140 °C) to form a refractive layer.

[0063] ④. Preparation of the absorption layer protective resin (organosilicon emulsion containing long-chain groups);

[0064] a. Raw material ratio (mass fraction%); Component A; [Methyltriethoxysilane C 12 H 20 O3 Si; Dimethyldiethoxysilane (DMDES); Hexamethyldisiloxane (HMDSO) / (ratio; 7; 2.5; 0.5); (97%). Catalyst; [Hydrochloric acid (HCl)]; (0.8%). Solvent; [120# solvent naphtha]; (appropriate amount), deionized water H 2 O; (120%); Component B; Composite emulsifier [AEO-7, OP-10 / (ratio; 3; 7)] (4%). Deionized water H 2 O; (appropriate amount).

[0065] b. Preparation of organosilicon oligomer; In a reaction kettle (equipped with a stirrer, reflux condenser, thermometer), add deionized water, concentrated hydrochloric acid, and 120# solvent naphtha according to a certain ratio, and dropwise add Component A under rapid stirring; after completion, heat under reflux for about 6 h and then cool to below 40 °C, remove water, and wash the organic layer with 5% Na 2 CO 3 solution 1 - 2 times, then wash with deionized water until neutral, dry over anhydrous calcium chloride, and distill under normal pressure to 150 °C to remove the solvent, and distill under reduced pressure at 180 °C and 133 Pa to remove low-boiling substances. The resulting product is a colorless transparent viscous liquid (organosilicon resin containing long-chain groups).

[0066] c. First, mix the composite emulsifier [[AEO-7, OP-10 / (ratio; 3; 7)] (4%) emulsifier with a small amount of water and stir evenly, add the organosilicon resin prepared by the above method, and stir until the system undergoes phase inversion and thickening, then slowly add the remaining water, taking care that the system can be dispersed in a timely manner, to obtain an organosilicon emulsion-based aqueous agent with a viscosity of about 0.05 Pa·s.

[0067] d. Meter this solution according to the coating film thickness; 6 g / m 2 (dry weight), coat it on the substrate film to form a refractive and dielectric layer through a coater, and dry it in a drying air duct device <140 °C to form a light absorption layer protection layer. Thus, the 'flexible optical variable film with light-induced angle-dependent color change' is prepared.

[0068] Example 2

[0069] ①. Nylon film (PA) is used as the substrate film. (Film thickness; 6 μm). Use vacuum thermal evaporation method (vacuum degree 0.9 pɑ) to deposit an AL layer with a thickness of about 5 nm on this substrate film to form an adhesive layer. (Metal AL wire > 99.0%).

[0070] ②. Then, use vacuum thermal evaporation method with a vacuum degree of 0.2 pɑ to deposit an aluminum thin film with a thickness of about 100 nm on the cadmium adhesive layer that has been formed on the substrate film, to form a high-reflection layer with a reflectance of T > 98% (metal, AL wire > 99.0%).

[0071] ③. Prepare a refractive and dielectric layer precursor by modifying acrylate resin with organosilicon oligomer;

[0072] a. Raw material ratio (parts by mass); Component A; [Phenyltriethoxysilane C 12 H 20 O 3 Si; Dimethyldiethoxysilane DMDES / (ratio; 1; 2.5)]; 85%. Deionized water H 2 O; 120%. Component B; [Acrylic acid (AA); 2-Hydroxyethyl methacrylate (HEMA); Butyl acrylate (BA) / (ratio; 7; 1; 2)]; 8%. Initiator; [Azobisisobutyronitrile (ABIN)]; 0.5%. Solvent; [Toluene C 7 H 8 ; (appropriate amount). Component C; Composite emulsifier [Span + Peregal span + O-20, OP-10 / (ratio; 3; 7] 3%. Deionized water H 2 O; (appropriate amount). Component E; Incorporate nano-aluminum flakes [AL (silver) thickness; 30 nm, light reflectivity; >98.0%] 0.5%.

[0073] b. Preparation of organosilicon oligomer; In a reaction kettle (equipped with a stirrer, reflux condenser, and thermometer), add Component A organosilicon monomer, and dropwise add concentrated hydrochloric acid until the solution pH is between 1 and 3. Heat up to 50 °C with stirring, dropwise add a certain amount of deionized water at a constant rate, react at 75 °C for 5 h, dropwise add 10% ammonia water to adjust the reaction solution to neutral, perform vacuum distillation, pour the product into a dry and clean container, and seal it for storage and standby.

[0074] c. Preparation of organosilicon-modified acrylate resin; Pour the organosilicon oligomer prepared in item b into a reaction kettle (equipped with a stirrer, reflux condenser, and thermometer), add an appropriate amount of solvent toluene (the liquid level can submerge the stirrer in the kettle), pass nitrogen, stir and heat up to 75 °C, then dropwise add Component B; the monomer and initiator mixture, and finish dropping in about 1 h, and react for about 1.5 h. Synthesize a solution with a viscosity of about 0.05 Pa·s as the dielectric layer precursor.

[0075] d. Doping of nano-aluminum flakes in the dielectric layer precursor; In a quantitative solution of 'organosilicon oligomer-modified acrylate resin polymer precursor', uniformly incorporate 1.2% of nano-aluminum flakes under stirring to make a solution with a low viscosity of 0.05 Pa·s doped with nano-aluminum flakes.

[0076] e. On the formed high-reflection layer base film, use a coater (draw machine (MDO), in-line coater) to evenly coat the prepared mixed solution d with low-viscosity doped nano-aluminum flakes on the formed high-reflection layer of the base film to form a refraction and dielectric layer, and dry it through a drying air duct device (drying zone temperature; <140 °C) to form a layer with a thickness of 8 g / m 2 (dry weight) of the'refraction and dielectric layer'.

[0077] ④. Preparation of the absorption layer protective resin (organosilicon emulsion containing long-chain groups);

[0078] a. Raw material ratio (mass fraction %); Component A; [methyltriethoxysilane C 7 H 18 O 3 Si:; dimethyldiethoxysilane DMDES; hexamethyldisiloxane HMDSO / (ratio; 7; 2.5; 0.5)]; (96%). Catalyst; [hydrochloric acid HCL]; (0.8%). Solvent; [120#L solvent oil]; (appropriate amount), deionized water H 2 O; (120%).; Component B; compound emulsifier [AEO-7, OP-10 / (ratio; 3; 7)] (3%). Deionized water H 2 O; (appropriate amount).

[0079] b. Preparation of organosilicon oligomer; In a reaction kettle (equipped with a stirrer, reflux condenser, thermometer), add deionized water, concentrated hydrochloric acid, and 120# solvent oil according to a certain ratio, and dropwise add Component A under rapid stirring; after completion, heat and reflux for about 6 h and then cool to below 40 °C, remove water, and wash the organic layer 1-2 times with 5% Na 2 CO 3 solution, and then wash with deionized water until neutral. After drying with anhydrous calcium chloride, distill at atmospheric pressure to 150 °C to remove the solvent, and distill under reduced pressure at 180 °C and 133 Pa to remove low-boiling substances. The obtained product is a colorless transparent viscous liquid (organosilicon resin containing long-chain groups).

[0080] c. First, mix Component B; the compound emulsifier and a small amount of water and stir evenly, add the organosilicon resin prepared by the above method and stir until the system changes phase and increases viscosity, and slowly add the remaining water, with the system being dispersed in a timely manner as the criterion, to obtain an organosilicon emulsion type water-based agent with a viscosity of about 10-15 centipoises.

[0081] d. Meter this solution according to the coating film thickness; 4 g / m 2 (dry weight), coat it on the formed refraction and dielectric layer of the base film through a coater, and dry it through a drying air duct device at <140 °C to form a light absorption layer protective layer. Thus, the 'flexible optical variable film with light-induced angle-dependent color change' is prepared.

[0082] Example 3

[0083] ①. The oriented polypropylene film (OPP) is used as the base film. (Film thickness: 40 μm). A polyol-modified acrylic crosslinking adhesive is selected and coated on the selected base film to form an adhesive layer;

[0084] a. Raw material ratio (mass fraction%); Component A; Glycerol GI: 12.8%, Sodium hypophosphite NaH 2 PO 2 : 1.16%, Polyvinyl alcohol PVA: 0.4%, OP-10: 0.06%, Deionized water H 2 O; : 27%. Component B; Acrylic acid AA: 32%, Ammonium persulfate (NH4) 2 SO 8 : 0.25%, Deionized water H 2 O; 12%.

[0085] b. Add Component A into the reaction kettle; stir and mix, heat up. When the temperature is greater than 85 °C, start to dropwise add Component B which has been stirred and mixed evenly in advance, and react at <90 °C. Control the dropping speed of the dropping solution according to the reaction temperature, and the dropping time is about 3.5 - 4.0 hours. Heat up to 95 °C within half an hour after dropping. Keep warm for 2 hours and then cool down. Thus, the polyol-modified acrylic crosslinking adhesive is obtained (viscosity 0.08 Pa·s, solid content: 45%).

[0086] C. Use a coater (draw machine (MDO), on-line coater) to evenly coat the 'polyol-modified acrylic crosslinking adhesive solution' on the surface of the base material (OPP) film at a rate of 8 g / m 2 d (dry weight), and dry it at <150 °C through a drying air duct device to form a polyol-modified acrylic crosslinking adhesive layer.

[0087] ②. Then, use the vacuum thermal evaporation method to deposit an aluminum film with a thickness of about 100 nm on the adhesive layer already formed on the base film under a vacuum degree of 0.2 Pa, to form a high-reflection layer with a reflectance of T > 98% (the purity of the metal and AL wire is > 99.0%).

[0088] ③. Prepare a refractive and dielectric layer precursor with an organosilicon oligomer-modified acrylate resin;

[0089] a. Raw material ratio (mass fraction); Component A; [Monophenyltriethoxysilane C 12 H 20 O 3 Si; Dimethyldiethoxysilane DMDES / (ratio; 1; 2.5)]; 88%. Deionized water H 2O; 120%. Component B; [Acrylic acid (AA); 2-Hydroxyethyl methacrylate (HEMA); Butyl acrylate (BA) / (proportion; 7; 1; 2)]; 15%. Initiator; [2,2'-Azobis(2-methylpropionitrile) (ABIN)]; 0.5%. Solvent; [Toluene DMDES]; (appropriate amount). Component C; Compound emulsifier [Span + Peregal span + O-20, OP-10 / (proportion; 3; 7)] 4%. Deionized water H 2 O; (appropriate amount). Component E; Incorporate nano aluminum flakes [AL (silver) thickness; 50 nm, light reflectivity; >98.0%] 1.2%.

[0090] b. Preparation of organosilicon oligomer; In a reaction kettle (equipped with a stirrer, reflux condenser, and thermometer), add component A organosilicon monomer, and dropwise add concentrated hydrochloric acid until the pH of the solution is between 1 and 3. While stirring, heat up to 50 °C, and dropwise add a certain amount of deionized water at a constant rate. React at 75 °C for 5 h, dropwise add 10% ammonia water to adjust the reaction solution to neutral, and perform vacuum distillation. Pour the product into a dry and clean container and seal it for standby. Vacuum distillation.

[0091] c. Preparation of organosilicon-modified acrylate resin; Pour the organosilicon oligomer prepared in item b into a reaction kettle (equipped with a stirrer, reflux condenser, and thermometer), add an appropriate amount of solvent toluene (the liquid level only needs to submerge the stirrer in the kettle), pass nitrogen, stir and heat up to 75 °C, then dropwise add component B; the monomer and initiator mixture, and finish dropping in about 1 h, and react for about 1.5 h. Synthesize a solution with a viscosity of about 0.08 Pa·s as the precursor of the dielectric layer.

[0092] d. Doping of nano aluminum flakes in the polymer precursor; In a quantitative solution of 'organosilicon oligomer-modified acrylate resin polymer precursor', uniformly incorporate 1.2% of nano aluminum flakes under stirring to prepare a solution with a low viscosity of 0.08 Pa·s doped with nano aluminum flakes.

[0093] e. On the formed high-reflection layer substrate film, use a coater (draw frame (MDO), in-line coater) to uniformly coat the prepared mixed solution d with low viscosity doped with nano aluminum flakes on the formed high-reflection layer of the substrate film to form a refractive and dielectric layer, and dry it through a drying air duct device (drying zone temperature; <140 °C) to form a 'refractive and dielectric layer' with a thickness of 8 g / m 2 (dry weight).

[0094] ④. Preparation of the absorbent layer protective resin (organosilicon emulsion containing long-chain groups); Component A; [Methyltriethoxysilane C 7 H 18 O 3Si: ;; Dimethyldiethoxysilane DMDES; Hexamethyldisiloxane HMDSO / (Ratio; 7; 2.5; 0.5)]; (88%). Catalyst; [Hydrochloric acid HCL]; (0.8%). Solvent; [120#L solvent oil]; (appropriate amount), deionized water H 2 O; (120%).; Component B; Compound emulsifier [AEO-7, OP—10 / (Ratio; 3; 7)] (4%). Deionized water H 2 O; (appropriate amount).

[0095] b. Preparation of organosilicon oligomer; In a reaction kettle (equipped with a stirrer, reflux condenser, and thermometer), add deionized water, concentrated hydrochloric acid, and 120# solvent oil according to a certain ratio, and dropwise add Component A under rapid stirring; after completion, heat under reflux for about 6 h and then cool to below 40°C, remove water, and wash the organic layer with 5% Na 2 CO 3 solution 1 - 2 times, then wash with deionized water until neutral, dry over anhydrous calcium chloride, and distill at atmospheric pressure to 150°C to remove the solvent, and distill under reduced pressure at 180°C and 133 Pa to remove low-boiling substances. The resulting product is a colorless transparent viscous liquid (organosilicon resin containing long-chain groups).

[0096] c. First, mix and stir evenly the Component B; compound emulsifier with a small amount of water, add the organosilicon resin prepared by the above method, and stir until the system undergoes phase inversion and thickening, then slowly add the remaining water, taking care that the system can be dispersed in a timely manner, to obtain an organosilicon emulsion-based water agent with a viscosity of about 0.07 Pa·s.

[0097] d. Coat this solution with a film thickness of; 5 / m 2 (dry weight) measured, and coat it on the substrate film through a coater to form a refractive and dielectric layer, and dry it in a drying air duct equipment at <140°C to form a light absorption layer and a protective layer. Thus, the 'flexible optical variable film with light-induced angle-dependent color change' is prepared.

[0098] Example 4

[0099] ①. Biaxially oriented polypropylene film (B0PP) is used as the substrate film. (Film thickness; 36μm). Select 'polyol-modified acrylic crosslinking adhesive' and coat it on the selected substrate film to form a bonding layer; its formulation and process are the same as those in a, b, c of [Example 3], and a 'polyol-modified acrylic crosslinking' adhesive bonding layer is formed on the selected substrate film.

[0100] ②. Then, use the vacuum thermal evaporation method with a vacuum degree of 0.2 pɑ to deposit an aluminum film with a thickness of about 100 nm on the bonding layer already formed on the substrate film, to form a high-reflection layer with a reflectance of T > 98% (the purity of metal, AL wire is > 99.0%).

[0101] ③. Prepare the refractive and dielectric layer precursor by modifying acrylate resin with organosilicon oligomer; a. Raw material ratio (parts by mass); Component A; [monophenyltriethoxysilane C 12 H 20 O 3 Si; dimethyldiethoxysilane DMDES / (ratio; 1; 2.5)]; 86%. Deionized water H 2 O; 120%. Component B; [acrylic acid (AA); 2-hydroxyethyl methacrylate (HEMA); butyl acrylate (BA) / (ratio; 7; 1; 2)]; 12%. Initiator; [azobisisobutyronitrile (ABIN)]; 0.4%. Solvent; [toluene DMDES]; (appropriate amount). Component C; compound emulsifier [span + peregal span + O-20, OP-10 / (ratio; 3; 7)] 4%. Deionized water H 2 O; (appropriate amount). Component E; doped with nano aluminum flakes [AL (gold) thickness; 50 nm, light reflectivity; >98.0%] 1.0%.

[0102] b. Preparation of organosilicon oligomer; c. Preparation of organosilicon-modified acrylate resin; The process is the same as b and c in [Example 3].

[0103] d. Doping of nano aluminum flakes in the polymer precursor; In a quantitative solution of 'organosilicon oligomer-modified acrylate resin polymer precursor', 1.0% of nano aluminum flakes (gold) are uniformly incorporated under stirring to form a solution with doped nano aluminum flakes and a low viscosity of 0.05 pa·s.

[0104] e. On the formed high-reflection layer substrate film, use a coater (draw machine (MDO), on-line coater) to uniformly coat the prepared mixed solution d with doped nano aluminum flakes and low viscosity on the formed high-reflection layer of the substrate film to form the refractive and dielectric layer, and dry it through a drying air duct device (drying zone temperature; <140 °C) to form a 'refractive and dielectric layer' with a thickness of 8 g / m 2 (dry weight). A refractive layer is coated on the formed high-reflection layer of the selected substrate film.

[0105] ④. Preparation of the absorbent layer protective resin (organosilicon emulsion containing long-chain groups);

[0106] a. Raw material ratio (mass fraction %); b. Preparation of organosilicon oligomer; c. Emulsification of organosilicon resin containing long-chain groups; d. Coating and drying on the organosilicon emulsion type water-based film; The formula and process are the same as a, b, c, and d in [Example 3]. Thus, the 'flexible photochromic film with light-induced angle-dependent color change' is prepared.

[0107] Using the raw material formula and process conditions of Manufacturing Method (A) of the present invention, a flexible photochromic film with angle-dependent color change is prepared (test data is shown in Table 1).

[0108] Table 1 shows the test data of Example 1, Example 2, Example 3, and Example 4

[0109]

[0110]

[0111]

[0112] In summary, the above are only the preferred embodiments of the present invention and are not used to limit the scope of implementation of the present invention. That is, all equivalent changes and modifications made to the content within the scope of the patent application of the present invention shall fall within the technical scope of the present invention.

Claims

1. A flexible photochromic film with angle-dependent color change, characterized in that , the flexible photochromic film with angle-dependent color change includes a substrate film, an adhesive layer, a reflective layer, a refractive layer, and a protective layer arranged from the inside out; The substrate film includes one of biaxially oriented polyester film BOPET, biaxially oriented polypropylene film BOPP, oriented polypropylene film OPP, and nylon film PA; The adhesive layer is a modified acrylic crosslinking adhesive, or a vacuum-coated thermal evaporation cadmium or aluminum film; The reflective layer is a vacuum-coated thermal evaporation aluminum film; The refractive layer is an organosilicon oligomer-modified acrylate resin doped with nano-scale flaky aluminum powder; The protective layer is an organosilicon emulsion-type adhesive solution containing long-chain groups; The adhesive layer and reflective layer of the photochromic film are prepared by vacuum-coated thermal evaporation coating method in sequence, and the refractive layer and protective layer of the photochromic film are prepared by solution coating method to obtain a flexible photochromic film with angle-dependent color change; Select a modified acrylic crosslinking adhesive modified with polyol, and coat it on the selected substrate film to form an adhesive layer. The preparation process of the modified acrylic crosslinking adhesive modified with polyol is as follows: (1) Raw material ratio, by mass fraction, Component A: glycerol: 12.8%, sodium hypophosphite: 1.16%, polyvinyl alcohol: 0.4%, emulsifier OP-10: 0.06%, deionized water H 2 O: 27%; Component B: acrylic acid: 32%, ammonium persulfate: 0.25%, deionized water H2O: 12%; where the ratio of Component A to Component B is 1:1.5; (2) Add component A to the reaction kettle at room temperature; stir and mix, start heating under stirring, and start dropping component B which has been stirred and mixed evenly when the temperature is greater than 85°C; at this time, the reaction temperature shall not be greater than 90°C, control the dropping speed of the dropping liquid according to the reaction temperature, the dropping time is 3.5 - 4.0 hours, heat up to 95°C within half an hour after dropping, and stop the reaction after holding at 95°C for 2 hours to obtain the modified acrylic crosslinking adhesive modified with polyol; the viscosity of the obtained modified acrylic crosslinking adhesive modified with polyol is 0.05 - 0.07 Pa·s, the solid content is 45 - 50%, and the film curing temperature is 90 - 140°C; (3) Use a coating machine to coat according to the thickness of the coating film: 6 - 8 g / m². 2 Measure and evenly coat the polyol-modified acrylic crosslinking adhesive solution on the surface of the substrate film, and dry it through a drying air duct device at a temperature of < 140 °C in the drying section to form a bonding layer.

2. A flexible photochromic film with angle-dependent color change according to claim 1, characterized in that, Select one of biaxially oriented polyester film BOPET, biaxially oriented polypropylene film BOPP, oriented polypropylene film OPP, and nylon film PA as the substrate film, and the thickness of the substrate film is 6 - 36 μm.

3. A flexible photochromic film with angle-dependent color change according to claim 2, characterized in that, Under a vacuum of 0.9 - 0.2 pɑ, a cadmium or aluminum film layer with a thickness of 1 - 5 nm is deposited on the substrate film by vacuum thermal evaporation method to form an adhesive layer.

4. A flexible photochromic film with angle-dependent color change according to claim 3, characterized in that, On the adhesive layer already formed on the substrate film, an aluminum film with a thickness less than 100 nm is deposited by vacuum thermal evaporation method to form an opaque reflective layer.

5. A flexible photochromic film with angle-dependent color change according to claim 1, characterized in that, Prepare the refractive layer with an organosilicon oligomer-modified acrylate resin: (1) Raw material ratio, by mass: Component C: The ratio of phenyltriethoxysilane to dimethyldiethoxysilane is 1:2.5, the content is 85 - 88%, and deionized water is 120%; Component D: Acrylic acid, 2-hydroxyethyl methacrylate, butyl acrylate in a ratio of 7:1:2, with a content of 8-15%; initiator azobisisobutyronitrile 0.3-0.5%, a small amount of solvent toluene; Component E: Compound emulsifier, Span: Peregal O-20 or OP-10 in a ratio of (1+2):7, with a content of 3-4%; a small amount of deionized water; Among them, the ratio of C:D:E is 1:2:0.3; (2) Preparation of organosilicon oligomer; In a reaction kettle, add Component C and Component E according to a ratio of 1:0.3, and dropwise add concentrated hydrochloric acid until the pH of the solution is 1-3. Stir and heat up to 50°C, then dropwise add deionized water. After the addition is complete, keep the temperature constant for 40 min, continue to heat up to 75°C, and keep the temperature constant for 5 h. Then dropwise add ammonia water with a concentration of 10% to adjust the reaction solution to neutral. Conduct vacuum distillation to obtain the product organosilicon oligomer. Pour the product organosilicon oligomer into a dry and clean container, and seal it for standby; (3) Preparation of organosilicon-modified acrylate resin; Weigh the prepared organosilicon oligomer and pour it into the reaction kettle. Add solvent toluene to submerge the stirring paddle in the kettle. Pass nitrogen, start stirring, and heat up to 75°C. Then, according to the raw material ratio, dropwise add Component D into the kettle. Finish the dropwise addition in 1 h, react for 1.5 h, cool down and discharge to obtain organosilicon oligomer-modified acrylate resin, forming a solution with a low viscosity of 0.05-0.07 Pa·s, which is the precursor of the dielectric layer; (4) Doping of nano-aluminum flakes in the dielectric layer precursor; In the prepared polymer precursor solution of organosilicon oligomer-modified acrylate resin, uniformly and quantitatively incorporate nano-aluminum flakes with a particle size of 30-50 nm under stirring. The addition ratio is; 0.5-1.2%, to achieve uniform doping, forming a solution of doped nano-aluminum flakes with a low viscosity of 0.05-0.07 Pa·s.

6. A flexible photochromic film with angle-dependent color change according to claim 5, characterized in that, The solution with a low viscosity of doped nano-aluminum flakes is uniformly coated on the formed refractive layer of the substrate film by a coater, and dried at 100-150°C through a drying air duct device to form a refractive layer.

7. A flexible photochromic film with angle-dependent color change according to claim 1, characterized in that, The preparation method of the protective layer is as follows: (1) Raw material ratio, in parts by mass: Component F: The ratio of methyltriethoxysilane, dimethyldiethoxysilane, and hexamethyldisiloxane HMDSO is 7:2.5:0.5, and the content ratio of Component F is 96-97%; the catalyst is hydrochloric acid, with a content of 0.8%, the solvent is 120#L of solvent oil, and the content of deionized water is 120%; Component G composite emulsifier, the ratio of AEO-3:OP-10 is 3:7, the content is 3-4%, and a small amount of deionized water H 2 O; (2) Preparation of organosilicon oligomer emulsion adhesive; in a reaction kettle, deionized water, concentrated hydrochloric acid, and 120#L solvent oil are added in a certain ratio, and component F is added dropwise under rapid stirring; after the addition is completed, heat under reflux for 6 h, cool to below 40 °C, remove the water layer, wash the organic layer twice with 5% sodium carbonate solution, and then wash with deionized water until neutral. After drying with anhydrous calcium chloride, distill at atmospheric pressure to 150 °C to remove the solvent, and under the conditions of 180 °C and 133 Pa, distill under reduced pressure to remove low-boiling substances. The obtained product is a colorless transparent viscous liquid, which is an organosilicon oligomer resin containing long-chain groups; then mix component G with a small amount of water and stir to completely disperse the emulsifier in the water, and then add the above-prepared organosilicon resin according to the formula, continue to stir until the system undergoes phase inversion and thickening, slowly add the remaining water at a rate that the system can be dispersed in time, and continue to stir for 30 min after the addition of water is completed to obtain an organosilicon emulsion adhesive containing long-chain groups with a viscosity of 0.05 - 0.08 Pa·s; (3) Use a coating machine to coat according to the thickness of the coating film; 4 - 6 g / m 2 Measure, and evenly coat the silicone emulsion adhesive solution containing long-chain groups on the substrate film to form a refractive and dielectric layer. After drying through a drying air duct device at <140°C, a light absorption layer protection layer is formed to obtain a flexible optical variable film with light-induced angle-dependent color change.

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