High hardness pet-resistant flexible optical window film and method of making same

Abstract

The application discloses a high-hardness pet-resistant flexible optical window film and a preparation method thereof, and relates to the technical field of polymer film materials.The preparation method of the optical window film comprises the following steps: mixing thermoplastic polyurethane and a light stabilizing additive, extruding and granulating to obtain a master batch, mixing the master batch with the thermoplastic polyurethane, and then extruding, casting, stretching and heat setting to obtain a base material layer; scraping and coating an adhesive on the surface of the base material layer, controlling the coating speed to be 5-10 m / min, drying the adhesive at 80-90 DEG C for 1-2 min, coating an anti-scratching and wear-resistant coating material, baking the coating material at 80-100 DEG C for 2-3 min, and then winding the coating material after cooling to obtain the high-hardness pet-resistant flexible optical window film; wherein the anti-scratching and wear-resistant coating material comprises wear-resistant fillers, the wear-resistant fillers are surface-modified silicon balls, the silicon balls are further grafted with isocyanate groups to be functionally modified, and zinc ions are introduced to form coordination bonds, so that the protective effect of the coating material is effectively realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high-molecular film materials, and particularly relates to a high-hardness pet-resistant flexible optical window film and a preparation method thereof. BACKGROUND

[0002] Polyurethane window films have become a commonly used material in building and home decoration due to their excellent light transmittance, heat insulation and decoration. However, with the popularity of pet-keeping in recent years, window films face new challenges in the process of use, such as damage caused by scratching of pets (especially cats and dogs). Because the surface hardness of traditional polyurethane films is insufficient, scratches are easily produced in the process of production and use, affecting the appearance and service life.

[0003] At present, common solutions to the durability problem of polyurethane window films include: 1. In terms of material modification, the hardness and wear resistance of polyurethane window films are enhanced by adding nanoparticles, such as adding silica, alumina and other nanoparticles. These nanoparticles are uniformly dispersed in the polyurethane matrix to form a rigid support structure, effectively improving the ability of the window film surface to resist scratching by pet claws. However, the amount of nanoparticles added and the uniformity of dispersion are difficult to control, and excessive addition may cause the flexibility of the window film to decrease, resulting in embrittlement and affecting the installation and use effect; 2. A wear-resistant coating is applied to the surface of the polyurethane window film, but the adhesion between the coating and the polyurethane matrix is a key problem. If the adhesion is not firm, the coating is easy to fall off during pet scratching or long-term use, losing its protective effect; 3. The performance of polyurethane window films is improved by crosslinking technology to increase the crosslinking density between molecular chains, making the window film structure more stable and improving the tear resistance and wear resistance. However, excessive crosslinking will reduce the transparency of the window film, affecting its optical performance, and the crosslinking process is difficult to control, increasing the production cost; 4. A multi-layer composite structure is used to enhance the mechanical properties, but it increases the thickness of the window film, affecting the light transmittance and flexibility.

[0004] In addition, polyurethane window films are also affected by environmental factors such as light, temperature and humidity during long-term use, and the inherent defects of polyurethane further restrict the service life of the window film, such as light aging sensitivity and insufficient wear resistance. Therefore, under the dual action of pet scratching and complex environmental factors, the durability of polyurethane window films is severely tested, and it is urgent to improve the material formula and optimize the production process to meet the actual use needs of pet-keeping families. SUMMARY

[0005] The present application relates to the technical field of high-molecular film materials, and particularly relates to a high-hardness pet-resistant flexible optical window film and a preparation method thereof.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical scheme:

[0007] A preparation method of a high-hardness pet-resistant flexible optical window film, comprising the following preparation steps:

[0008] S1: thermoplastic polyurethane is mixed with light stabilizer and extruded and granulated to obtain a master batch, which is mixed with thermoplastic polyurethane and then extruded and granulated, melted and extruded, cast, stretched and heat set to obtain a base layer;

[0009] S2: an adhesive is scraped on the surface of the base layer, the coating speed is controlled to be 5-10 m / min, an anti-scratch and wear-resistant coating is coated after drying at 80-90℃ for 1-2 min, and the film is cooled and wound after baking at 80-100℃ for 2-3 min, to obtain the high-hardness pet-resistant flexible optical window film;

[0010] Preferably, the preparation steps of the anti-scratch and wear-resistant coating are as follows:

[0011] s2.1: boric acid and melamine are placed in deionized water, zinc nitrate hexahydrate is added, and stirring evaporation is carried out at 100-120℃, followed by drying at 80℃ for 10-12h, calcination at 1000-1200℃ under ammonia atmosphere for 1-2h, to obtain doped boron nitride, which is ultrasonically dispersed in deionized water, hydrochloric acid dopamine and Tris buffer are added to adjust the pH of the system to 7.8-8.0, and the system is heated to 60-70℃ and reacted for 4-5h, then filtered, transferred to deionized water, adjusted to pH 7.8-8.0 with Tris buffer, and added with tetraethyl orthosilicate, and hydrolyzed for 6-8h, then filtered and washed, to obtain composite particles;

[0012] s2.2: propyl triethoxysilane isocyanate and 2,6-diaminopyridine are respectively dissolved in an equal amount of N,N-dimethylformamide by stirring, mixed and stirred for 10-20min, heated to 70-80℃ and reacted for 2-3h, then added with zinc chloride acetonitrile solution, stirred and dispersed, and dried to obtain a viscous liquid, which is transferred into an ethanol aqueous solution, stirred for 20-30min, added with the ethanol dispersion of the composite particles prepared in step s2.1, heated to 50-60℃ and stirred for 6-8h, and then washed with alcohol and water alternately, and dried to obtain a wear-resistant filler;

[0013] s2.3: isophorone diisocyanate is added to N,N-dimethylacetamide, dissolved by stirring at 50-60℃, added with polyether diol and dibutyltin dilaurate, heated to 60-80℃ under nitrogen atmosphere and stirred for 2-4h, then added with a chain extender and reacted for 12-16h, cooled to 40-45℃, added with triethylamine and stirred for 15-20min to obtain a polyurethane emulsion, added with the wear-resistant filler prepared in s2.2, leveling agent, thickening agent, defoaming agent and wetting dispersant, stirred for 30min, defoamed after standing, to obtain the anti-scratch and wear-resistant coating;

[0014] Preferably, the anti-scratching wear-resistant coating comprises, by mass fraction: 25-30 parts of polyurethane emulsion, 1-3 parts of wear-resistant filler, 0.2-0.5 parts of leveling agent, 0.3-0.5 parts of thickening agent, 0.1-0.3 parts of defoaming agent, 0.3-0.5 parts of wetting dispersant; wherein the solid content of the polyurethane emulsion is 30-35%;

[0015] Preferably, the molar ratio of boric acid, melamine and zinc nitrate hexahydrate in s2.1 is 7:1:(0.01-0.05); the dosage ratio of boron nitride, dopamine hydrochloride and tetraethyl orthosilicate is 5g:1g:(3-6)mL;

[0016] Preferably, the molar ratio of isocyanate propyl triethoxysilane, 2,6-diaminopyridine and zinc chloride in s2.2 is 1:1:(0.5-1), and the dosage of isocyanate propyl triethoxysilane is 30-50wt% of the composite particles;

[0017] Preferably, the molar ratio of isocyanate groups of isophorone diisocyanate to the total amount of hydroxyl groups in polyether diol and chain extender in s2.3 is 1:1; the chain extender is any one of bis(4-hydroxyphenyl)disulfide and bis(2-hydroxyethyl)disulfide;

[0018] Preferably, the dosage of the light stabilizing aid in the substrate layer is 1.5-2.0wt%;

[0019] Preferably, the preparation steps of the light stabilizing aid are as follows: cyanuric chloride is placed in toluene, N-n-butyl-2,2,6,6-tetramethyl-4-piperidinamine is added under ice water bath, sodium hydroxide is added after 2h of reaction, the temperature is raised to 70-80℃ for 12-14h of reaction, then extraction and drying, mixed with aluminum chloride and chlorobenzene is added, stirred under ice water bath for 20-30min, then m-dihydroxybenzene is added, the temperature is raised to 80℃ for 3-4h of reaction, dilute hydrochloric acid is added dropwise, heated, filtered, washed and dried, then transferred into N,N-dimethylformamide, potassium carbonate is added, the mixed solution of chloromethyl triethoxysilane and N,N-dimethylformamide is added dropwise at 80℃, continue to react for 5-6h, filtered and dried to obtain the silane-modified light stabilizer; nano-zirconium dioxide is placed in anhydrous ethanol, ultrasonic dispersion for 20-30min, then the silane-modified light stabilizer is added, stirred, the temperature is raised to 60℃ for 4-6h of reaction, centrifuged and dried, ball milled and sieved to obtain the light stabilizing aid;

[0020] Preferably, the molar ratio of cyanuric chloride, N-n-butyl-2,2,6,6-tetramethyl-4-piperidinamine, m-dihydroxybenzene and chloromethyl triethoxysilane is 1:2:(1-1.5):(1-1.5); the mass ratio of nano-zirconium dioxide to the silane-modified light stabilizer is 1:(3-5);

[0021] A high-hardness pet-resistant flexible optical window film prepared by the above preparation method;

[0022] Preferably, the thickness of the substrate layer is 50-120 μm;

[0023] Preferably, the adhesive is an acrylate adhesive, and the coating thickness is 5-10 μm;

[0024] Preferably, the thickness of the anti-scratch wear-resistant coating is 10-20 μm.

[0025] Compared with the prior art, the present application has the following advantages:

[0026] 1. The window film prepared by the present application comprises a thermoplastic polyurethane as a substrate layer, an acrylate adhesive coated on the surface of the substrate layer, and an anti-scratch wear-resistant coating obtained by pre-curing the adhesive to maintain a certain bonding effect; the light stabilizer structure is loaded on zirconium dioxide, which effectively improves the migration resistance and thermal stability of the light stabilizer, and improves the dispersion of the zirconium dioxide nanoparticles, enhances the mechanical properties of the substrate layer, and increases the strength and toughness; the anti-scratch wear-resistant coating is obtained by mixing polyurethane emulsion, wear-resistant filler and a small amount of additives, the polyurethane emulsion realizes self-repairing performance of the coating by adding a chain extender containing a disulfide bond and hydrogen bonds, and because the wear-resistant filler has a certain thermal conductivity, the self-repairing rate is further improved, and the addition of the wear-resistant filler has a reinforcing effect, which improves the hardness and wear resistance of the coating;

[0027] 2. The wear-resistant filler is composed of boron nitride and silica particles, wherein Zn ions are introduced during the preparation of boron nitride, which has a certain chelating effect with dopamine and helps to enhance the interfacial bonding between polydopamine and boron nitride, and improves the deposition of silica, and the BN-PDA-SiO2 composite structure improves the reinforcing effect of the particles in the coating; in order to improve the dispersion of the wear-resistant material in the polyurethane, the particles are modified by introducing isocyanate groups and introducing zinc ion coordination bonds to improve the interfacial connection between the wear-resistant filler and the polyurethane, and enhance the protective performance of the coating in the window film. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present application will be described below in a clear and complete manner. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0029] In the experiment, the brand of thermoplastic polyurethane is 58280, which is from Lubrizol; the polyether diol is polytetramethylene ether glycol, PTMEG1000, which is from BASF Mitsubishi PTG; the average particle size of nano zirconium dioxide is 20 nm, which is purchased from Jining Zhongkai New Material; the adhesive is 3M acrylate adhesive, the model is DP810NS; the leveling agent is J2102, the thickening agent is J0604, the defoaming agent is J0403, and the wetting dispersing agent is J1702, which are all purchased from Shenzhen Jitian Chemical;

[0030] The preparation steps of the polyurethane emulsion are: 5 mol isophorone diisocyanate is added to N,N-dimethylacetamide, after stirring and dissolving at 60°C, 3 mol polyether diol and 10 g dibutyltin dilaurate are added, and after stirring for 4 h under nitrogen atmosphere, the temperature is raised to 80°C, 2 mol bis(4-hydroxyphenyl)disulfide is added and the reaction is continued for 12 h, and then the temperature is cooled to 40°C, 0.1 mol triethylamine is added and stirred for 15 min to obtain the polyurethane emulsion; the solid content of the polyurethane emulsion is 32%;

[0031] The preparation steps of the light stabilizing aid are: 1 mol cyanuric chloride is placed in 1 L of toluene, 2 mol N-n-butyl-2,2,6,6-tetramethyl-4-piperidinamine is added under ice water bath, the reaction is continued for 2 h, then 100 mL of 0.02 mol / L concentrated sodium hydroxide is added dropwise, the temperature is raised to 70°C, the reaction is continued for 14 h, then extraction and drying are performed, 1 mol aluminum chloride is mixed, 1 L of chlorobenzene is added, stirring is continued for 30 min under ice water bath, then 1.1 mol of resorcinol is added, the temperature is raised to 80°C, the reaction is continued for 4 h, 100 mL of 3% dilute hydrochloric acid is added dropwise, heating, filtration, washing and drying are performed, then it is transferred into 500 mL of N,N-dimethylformamide, 10 g of potassium carbonate is added, 1.2 mol of chloromethyl triethoxysilane and 500 mL of N,N-dimethylformamide are added dropwise under 80°C, the reaction is continued for 6 h, then filtration and drying are performed to obtain the silane-modified light stabilizer; the nano zirconium dioxide is placed in 500 mL of absolute ethanol, ultrasonic dispersion is continued for 30 min, then the silane-modified light stabilizer is added, the temperature is raised to 60°C, the reaction is continued for 5 h, then centrifugal drying and ball milling are performed to obtain the light stabilizing aid; the mass ratio of nano zirconium dioxide to silane-modified light stabilizer is 1:3;

[0032] Example 1: The present embodiment provides a preparation method of a high-hardness pet-resistant flexible optical window film, which specifically comprises the following steps:

[0033] S1: 20 parts of thermoplastic polyurethane and light stabilizing aid are mixed and placed in a double-screw extruder, the sample is extruded and then granulated by a pelletizer to obtain a master batch, which is mixed with 80 parts of thermoplastic polyurethane, then extruded and granulated, and then melt-extruded at 200°C, drawn longitudinally and transversely on a cooling roller, and then heat-set to obtain a base layer with a thickness of 120 μm; the amount of light stabilizing aid in the base layer accounts for 2.0 wt%.

[0034] S2: The adhesive is applied on the surface of the substrate layer by doctor blade coating, the coating speed is controlled at 8 m / min, the coating thickness is 10 μm, after drying at 80℃ for 2 min, the coating thickness is 20 μm, the anti-scratch wear-resistant coating is applied, after baking at 90℃ for 2 min and cooling, the product is wound to obtain a window film product;

[0035] The anti-scratch wear-resistant coating comprises 30 parts of polyurethane emulsion, 3 parts of wear-resistant filler, 0.2 parts of leveling agent, 0.5 parts of thickening agent, 0.5 parts of defoaming agent, and 0.3 parts of wetting dispersant.

[0036] The preparation steps of the wear-resistant filler are as follows:

[0037] s1: 4.33 g of boric acid and 1.28 g of melamine are placed in deionized water, 0.03 g of zinc nitrate hexahydrate is added, and the mixture is stirred and evaporated at 120℃, then dried at 80℃ for 12 h, calcined at 1200℃ for 2 h in an ammonia atmosphere, to obtain doped boron nitride, 5 g of the doped boron nitride is placed in 500 mL of deionized water and ultrasonically dispersed, 1 g of dopamine hydrochloride and Tris buffer are added to adjust the pH of the system to 7.8, and the temperature is raised to 70℃ and reacted for 5 h, then cooled and filtered, transferred to 500 mL of deionized water, and Tris buffer is added to adjust the pH of the system to 8.0, then 5 mL of tetraethyl orthosilicate is added and hydrolyzed for 8 h, then filtered and washed to obtain composite particles;

[0038] s2: 2.50 g of propyl triethoxysilane isocyanate and 1.10 g of 2,6-diaminopyridine are respectively placed in equal amounts of 500 mL of N,N-dimethylformamide, stirred and dissolved, then mixed and stirred for 20 min, the temperature is raised to 80℃ and kept for 2 h, then 10 mL of acetonitrile solution containing 1.38 g of zinc chloride is added, stirred and dispersed, then dried to obtain a viscous liquid, transferred into 100 mL of an ethanol aqueous solution, stirred for 30 min, then 100 mL of the ethanol dispersion of the composite particles prepared in step s1 is added, heated to 60℃ and stirred for 8 h, then washed with alcohol and water alternately, dried, and ground through a 200 mesh sieve to obtain the wear-resistant filler; the amount of propyl triethoxysilane isocyanate is 50 wt% of the composite particles.

[0039] Embodiment 2: The present embodiment provides a preparation method of a high-hardness pet-resistant flexible optical window film, which specifically comprises the following steps:

[0040] S1: 20 parts of thermoplastic polyurethane and light stabilizing aid are mixed and placed in a twin-screw extruder, the sample is extruded and granulated by a pelletizer to obtain a master batch, which is mixed with 80 parts of thermoplastic polyurethane, then extruded and granulated, melted and extruded at 200℃, longitudinally stretched and transversely stretched on a cooling roller, and heat set to obtain a substrate layer with a thickness of 120 μm; wherein the amount of light stabilizing aid in the substrate layer is 2.0 wt%;

[0041] S2: The adhesive is applied on the surface of the substrate layer by doctor blade coating, the coating speed is controlled at 8 m / min, the coating thickness is 10 μm, after drying at 80℃ for 2 min, the coating thickness is 20 μm, the anti-scratch wear-resistant coating is applied, after baking at 90℃ for 2 min and cooling, the product is wound to obtain a window film product;

[0042] The anti-scratch wear-resistant coating comprises 30 parts of polyurethane emulsion, 3 parts of wear-resistant filler, 0.2 parts of leveling agent, 0.5 parts of thickening agent, 0.5 parts of defoaming agent, and 0.3 parts of wetting dispersant.

[0043] The preparation steps of the wear-resistant filler are as follows:

[0044] s1: 4.32 g of boric acid and 1.26 g of melamine are placed in deionized water, 0.03 g of zinc nitrate hexahydrate is added, and stirring evaporation is carried out at 100℃, and then drying at 80℃ for 12 h, calcination at 1000℃ for 2 h in an ammonia atmosphere, to obtain doped boron nitride, 5 g of the doped boron nitride is ultrasonically dispersed in 500 mL of deionized water, 1 g of dopamine hydrochloride and Tris buffer are added to adjust the system pH to 7.8, and the temperature is raised to 70℃ for reaction for 5 h, after cooling, filtration is carried out, and then transferred to 500 mL of deionized water, Tris buffer is added to adjust the system pH to 8.0, 5 mL of tetraethyl orthosilicate is added, and hydrolysis is carried out for 8 h, then filtration and washing are carried out, to obtain composite particles;

[0045] s2: 2.50 g of propyl triethoxysilane isocyanate and 1.10 g of 2,6-diaminopyridine are respectively placed in equal amounts of 500 mL of N,N-dimethylformamide, stirring and dissolving are carried out, then mixing and stirring are carried out for 20 min, the temperature is raised to 80℃ for 2 h, then 10 mL of acetonitrile solution containing 1.38 g of zinc chloride is added, stirring and dispersion are carried out, then drying is carried out to obtain a viscous liquid, which is transferred into 100 mL of an ethanol aqueous solution, stirring is carried out for 30 min, then 100 mL of an ethanol dispersion solution of the composite particles prepared in step s1 is added, heating to 60℃ for stirring for 8 h, then alcohol and water are alternately washed, drying is carried out, and then a 200 mesh sieve is used for ball milling, to obtain the wear-resistant filler; the amount of propyl triethoxysilane isocyanate is 30 wt% of the composite particles.

[0046] Example 3: The present embodiment provides a preparation method of a high-hardness pet-resistant flexible optical window film, which specifically comprises the following steps:

[0047] S1: 20 parts of thermoplastic polyurethane and light stabilizing aid are mixed and placed in a twin-screw extruder, a sample strip is extruded, and then a pelletizer is used for granulation to obtain a master batch, which is mixed with 80 parts of thermoplastic polyurethane, then extruded and granulated, and then melt extruded at 200℃, drawn longitudinally and transversely on a cooling roller, and then heat set to obtain a substrate layer with a thickness of 120 μm; wherein the amount of light stabilizing aid in the substrate layer is 2.0 wt%.

[0048] S2: The adhesive is applied on the surface of the substrate layer by doctor blade coating, the coating speed is controlled at 8 m / min, the coating thickness is 10 μm, after drying at 80℃ for 2 min, the coating thickness is 20 μm, the anti-scratch wear-resistant coating is applied, after baking at 90℃ for 2 min and cooling, the window film product is obtained by winding;

[0049] The anti-scratch wear-resistant coating comprises 30 parts of polyurethane emulsion, 3 parts of wear-resistant filler, 0.2 parts of leveling agent, 0.5 parts of thickening agent, 0.5 parts of defoaming agent, and 0.3 parts of wetting dispersant.

[0050] The preparation steps of the wear-resistant filler are as follows:

[0051] s1: 4.33 g of boric acid and 1.27 g of melamine are placed in deionized water, 0.03 g of zinc nitrate hexahydrate is added, and the mixture is stirred and evaporated at 120℃, then dried at 80℃ for 12 h, calcined at 1200℃ for 2 h in an ammonia atmosphere, and then 5 g of the obtained doped boron nitride is ultrasonically dispersed in 500 mL of deionized water, 1 g of dopamine hydrochloride and Tris buffer are added to adjust the pH of the system to 7.8, and the system is heated to 70℃ and reacted for 5 h. After cooling, it is filtered and transferred to 500 mL of deionized water, Tris buffer is added to adjust the pH of the system to 8.0, 5 mL of tetraethyl orthosilicate is added, and the system is hydrolyzed for 8 h, then filtered and washed to obtain the composite particles;

[0052] s2: 2.50 g of propyl triethoxysilane isocyanate and 1.10 g of 2,6-diaminopyridine are respectively placed in equal amounts of 500 mL of N,N-dimethylformamide, stirred and dissolved, then mixed and stirred for 20 min, heated to 80℃ and reacted for 2 h, then 10 mL of acetonitrile solution containing 1.38 g of zinc chloride is added, stirred and dispersed, then dried to obtain a viscous liquid, which is transferred into 100 mL of an ethanol aqueous solution, stirred for 30 min, then 100 mL of the ethanol dispersion of the composite particles prepared in step s1 is added, heated to 60℃ and stirred for 8 h, then washed with alcohol and water alternately, dried, ground through a 200 mesh sieve to obtain the wear-resistant filler; the amount of propyl triethoxysilane isocyanate is 40 wt% of the composite particles.

[0053] Comparative Example 1: As a control experiment of Example 1, the light stabilizer in the substrate layer is replaced with a silane-modified light stabilizer without nano-zirconium dioxide, and the remaining steps and parameters are the same as those of Example 1.

[0054] The preparation steps of the silane-modified light stabilizer are as follows: 1 mol of cyanuric chloride is placed in 1 L of toluene, 2 mol of N-n-butyl-2, 2, 6, 6-tetramethyl-4-piperidinamine is added under ice water bath, 100 mL of 0.02 mol / L sodium hydroxide is added dropwise after 2 h of reaction, the temperature is increased to 70 DEG C, and the reaction is carried out for 14 h, then extraction and drying are carried out, 1 mol of aluminum chloride is mixed, 1 L of chlorobenzene is added, stirring is carried out under ice water bath for 30 min, then 1.1 mol of resorcinol is added, the temperature is increased to 80 DEG C, and the reaction is carried out for 4 h, 100 mL of 3% dilute hydrochloric acid is added dropwise, heating, filtration, washing and drying are carried out, and then the obtained product is transferred into 500 mL of N, N-dimethylformamide, 10 g of potassium carbonate is added, and 1.2 mol of chloromethyl triethoxysilane and 500 mL of N, N-dimethylformamide are added dropwise under 80 DEG C, and the reaction is carried out for 6 h, then filtration and drying are carried out, and the silane-modified light stabilizer is obtained.

[0055] Comparative Example 2: As a control experiment of Example 1, the composite particles of the wear-resistant filler in the scratch-resistant and wear-resistant coating are replaced by silica with a particle size of 50 μm, which is purchased from Shanghai Aldrin, and the specific steps are as follows:

[0056] S1: 20 parts of the thermoplastic polyurethane and the light stabilizing aid are mixed and placed in a double-screw extruder, and a sample strip is extruded, and then granulation is carried out by using a pelletizer to obtain a master batch, and then 80 parts of the thermoplastic polyurethane is mixed and extruded and granulated, and then melt extrusion is carried out at 200 DEG C, and then longitudinal stretching and transverse stretching are carried out on a cooling roller, and then heat setting is carried out to obtain a base layer with a thickness of 120 μm; wherein the amount of the light stabilizing aid in the base layer accounts for 2.0% by weight;

[0057] S2: The adhesive is scraped and coated on the surface of the base layer, the coating speed is controlled to be 8 m / min, the coating thickness is 10 μm, drying is carried out at 80 DEG C for 2 min, then the scratch-resistant and wear-resistant coating with a thickness of 20 μm is coated, baking is carried out at 90 DEG C for 2 min, and then cooling and winding are carried out to obtain a finished product of the window film;

[0058] The scratch-resistant and wear-resistant coating comprises 30 parts of polyurethane emulsion, 3 parts of wear-resistant filler, 0.2 parts of leveling agent, 0.5 parts of thickening agent, 0.5 parts of defoaming agent and 0.3 parts of wetting dispersant.

[0059] The preparation steps of the wear-resistant filler are as follows:

[0060] Respectively, 2.50 g of propyl triethoxysilane isocyanate and 1.10 g of 2, 6-diaminopyridine were dissolved in equal amounts of 500 mL N, N-dimethylformamide, stirred for 20 min, heated to 80 ℃ and reacted for 2 h, then 10 mL of acetonitrile solution containing 1.38 g of zinc chloride was added, stirred and dispersed, then dried to obtain a viscous liquid, transferred into 100 mL of ethanol aqueous solution, stirred for 30 min, then 100 mL of silica ethanol dispersion was added, heated to 60 ℃ and stirred for 8 h, then washed with alcohol and water alternately, dried and sieved to 200 mesh to obtain the wear-resistant filler; the amount of propyl triethoxysilane isocyanate is 50 wt% of the silica.

[0061] Comparative Example 3: As a control experiment of Example 1, the wear-resistant filler was replaced with composite particles, and the specific steps were as follows:

[0062] S1: 20 parts of thermoplastic polyurethane were mixed with light stabilizing additives and placed in a twin-screw extruder, and the extruded sample was pelletized by a pelletizer to obtain a masterbatch. After mixing with 80 parts of thermoplastic polyurethane and extruding and pelletizing, it was melt-extruded at 200 ℃, cast onto a cooling roller, and then longitudinally and transversely stretched to obtain a substrate layer with a thickness of 120 μm. The amount of light stabilizing additive in the substrate layer was 2.0 wt%.

[0063] S2: The surface of the substrate layer was coated with an adhesive, the coating speed was controlled at 8 m / min, the coating thickness was 10 μm, and after drying at 80 ℃ for 2 min, an anti-scratch wear-resistant coating with a thickness of 20 μm was coated, and after baking at 90 ℃ for 2 min, it was cooled and wound up to obtain a finished window film;

[0064] The anti-scratch wear-resistant coating includes 30 parts of polyurethane emulsion, 3 parts of composite filler, 0.2 parts of leveling agent, 0.5 parts of thickening agent, 0.5 parts of defoaming agent, and 0.3 parts of wetting dispersant.

[0065] The preparation steps of the composite particles are as follows: 4.33 g of boric acid and 1.28 g of melamine were placed in deionized water, 0.03 g of zinc nitrate hexahydrate was added, stirred and evaporated at 120 ℃, then dried at 80 ℃ for 12 h, calcined at 1200 ℃ for 2 h in an ammonia atmosphere to obtain boron nitride doped with nitrogen, 5 g of the boron nitride doped with nitrogen was dispersed in 500 mL of deionized water by ultrasonic dispersion, 1 g of dopamine hydrochloride and Tris buffer were added to adjust the pH of the system to 7.8, and the system was heated to 70 ℃ and reacted for 5 h. After cooling, it was filtered and transferred to 500 mL of deionized water, Tris buffer was added to adjust the pH of the system to 8.0, 5 mL of tetraethyl orthosilicate was added and hydrolyzed for 8 h, then filtered and washed.

[0066] Detection test

[0067] 1. The light transmittance of the window films prepared in Examples 1-3 and Comparative Examples 1-3 was determined by using the integrating sphere method of the UV-Vis spectrophotometer, with the wavelength range of 200-900 nm:

[0068] 2. The abrasion loss of the window films prepared in Examples 1-3 and Comparative Examples 1-3 was tested by using the BGD 523 abrasion tester, with the application of a 1 kg load, and the rotation of 500 times at a speed of 80 r / min;

[0069] 3. The hardness of the window films prepared in Examples 1-3 and Comparative Examples 1-3 was tested according to GB / T6739;

[0070] The above test data are recorded in the following table:

[0071]

[0072] From the above data, it can be seen that the comprehensive performance of Example 1 is better than that of the other examples, with good light transmittance and good abrasion resistance; in Comparative Example 1, the light stabilizer is not loaded with zirconium dioxide, resulting in uneven distribution of the light stabilizer, leading to a decrease in light transmittance and abrasion resistance; in Comparative Example 2, the original composite particles are replaced by zirconium dioxide, resulting in a significant decrease in hardness and abrasion resistance; in Comparative Example 3, the abrasion-resistant filler is not modified, resulting in easy peeling of the particle agglomeration, aggravation of the abrasion, and a decrease in hardness.

[0073] It is apparent for those skilled in the art that the present application is not limited to the details of the above exemplary embodiments, but can be implemented in other concrete forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be considered in all respects as illustrative and not restrictive, and the scope of the present application should be defined by the appended claims rather than the above description, and it is intended to encompass all changes falling within the meaning and scope of equivalents of the claims.

Claims

1. A method for preparing a high hardness pet resistant flexible optical window film, characterized in that, The preparation steps include: S1: thermoplastic polyurethane is mixed with a light stabilizer, extruded and granulated to obtain a master batch, mixed with thermoplastic polyurethane, extruded and granulated again, then melt extruded, cast, stretched and heat set to obtain a base layer; S2: a bonding agent is scraped on the surface of the base layer at a coating speed of 5-10 m / min, dried at 80-90℃ for 1-2 min, then coated with an anti-scratch wear-resistant coating, baked at 80-100℃ for 2-3 min, cooled and wound to obtain the high-hardness pet-resistant flexible optical window film; The preparation steps of the anti-scratch wear-resistant coating are: s2.1: boric acid and melamine are placed in deionized water, zinc nitrate hexahydrate is added, stirred and evaporated at 100-120℃, then dried at 80℃ for 10-12 h, calcined at 1000-1200℃ for 1-2 h in an ammonia atmosphere, to obtain doped boron nitride, which is dispersed in deionized water by ultrasonic, then hydrochloric acid dopamine and Tris buffer are added to adjust the pH of the system to 7.8-8, heated to 60-70℃ and reacted for 4-5 h, cooled, filtered, transferred to deionized water, adjusted to pH 7.8-8.0 with Tris buffer, added tetraethyl orthosilicate, hydrolyzed for 6-8 h, filtered and washed to obtain composite particles; s2.2: isocyanic acid propyl triethoxysilane and 2,6-diaminopyridine are respectively dissolved in an equal amount of N,N-dimethylformamide, mixed and stirred for 10-20 min, heated to 70-80℃ and reacted for 2-3 h, then zinc chloride acetonitrile solution is added, stirred and dispersed, then dried to obtain a viscous liquid, which is transferred into an ethanol aqueous solution, stirred for 20-30 min, then the ethanol dispersion of the composite particles prepared in step s2.1 is added, heated to 50-60℃ and stirred for 6-8 h, then washed with alcohol and water alternately, and dried to obtain a wear-resistant filler; s2.3: isophorone diisocyanate is added to N,N-dimethylacetamide, dissolved by stirring at 50-60℃, then polyether diol and dibutyltin dilaurate are added, heated to 60-80℃ under nitrogen atmosphere, stirred for 2-4 h, then a chain extender is added and reacted for 12-16 h, cooled to 40-45℃, then triethylamine is added and stirred for 15-20 min to obtain a polyurethane emulsion, then the wear-resistant filler prepared in s2.2, leveling agent, thickening agent, defoaming agent and wetting dispersant are added, stirred for 20-30 min, defoamed and then obtained is the anti-scratch wear-resistant coating.

2. The method for preparing a high-hardness, pet-resistant, flex-resistant optical window film according to claim 1, characterized in that, The anti-scratch wear-resistant coating comprises, by mass fraction: 25-30 parts of polyurethane emulsion, 1-3 parts of wear-resistant filler, 0.2-0.5 parts of leveling agent, 0.3-0.5 parts of thickening agent, 0.1-0.3 parts of defoaming agent, and 0.3-0.5 parts of wetting dispersant; wherein the solid content of the polyurethane emulsion is 30-35%.

3. The method for preparing a high-hardness, pet-resistant, flex-resistant optical window film according to claim 1, characterized in that, The molar ratio of boric acid, melamine and zinc nitrate hexahydrate in s2.1 is 7:1:(0.01-0.05); the ratio of the amount of doped boron nitride, hydrochloric acid dopamine and tetraethyl orthosilicate is 5 g:1 g:(3-6) mL.

4. The method for preparing a high-hardness, pet-resistant, flex-resistant optical window film according to claim 1, characterized in that, The molar ratio of propyl triethoxysilane isocyanate, 2,6-diaminopyridine and zinc chloride in s2.2 is 1:1:(0.5-1), and the amount of propyl triethoxysilane isocyanate is 30-50wt% of the composite particles.

5. The method for preparing a high-hardness, pet-resistant, flex-resistant optical window film according to claim 1, characterized in that, The molar ratio of isophorone diisocyanate isocyanate group to polyether diol and total hydroxyl group of chain extender in s2.3 is 1:1; the chain extender is any one of bis(4-hydroxyphenyl)disulfide and bis(2-hydroxyethyl)disulfide.

6. The method for preparing a high-hardness, pet-resistant, flex-resistant optical window film according to claim 1, characterized in that, The amount of the light stabilizing aid in the substrate layer is 1.5-2.0wt%, and the preparation steps of the light stabilizing aid are as follows: cyanuric chloride is placed in toluene, N-n-butyl-2,2,6,6-tetramethyl-4-piperidinamine is added under ice water bath, sodium hydroxide is added dropwise after 2h of reaction, the temperature is increased to 70-80℃, and the reaction is carried out for 12-14h, then extraction and drying are carried out, aluminum chloride is mixed and chlorobenzene is added, stirring is carried out under ice water bath for 20-30min, then resorcinol is added, the temperature is increased to 80℃, and the reaction is carried out for 3-4h, dilute hydrochloric acid is added dropwise, heating, filtration, washing and drying are carried out, then the obtained product is transferred into N,N-dimethylformamide, potassium carbonate is added, a mixed solution of chloromethyl triethoxysilane and N,N-dimethylformamide is added dropwise at 80℃, the reaction is continuously carried out for 5-6h, filtration and drying are carried out, and the silane-modified light stabilizer is obtained; nano-zirconium dioxide is placed in anhydrous ethanol, ultrasonic dispersion is carried out for 20-30min, then the silane-modified light stabilizer is added, stirring is carried out, the temperature is increased to 60℃, and the reaction is carried out for 4-6h, centrifugal drying is carried out, ball milling is carried out, and the light stabilizing aid is obtained after sieving.

7. The method for preparing a high-hardness, pet-resistant, flex-resistant optical window film according to claim 6, characterized in that, The molar ratio of cyanuric chloride, N-n-butyl-2,2,6,6-tetramethyl-4-piperidinamine, resorcinol and chloromethyl triethoxysilane is 1:2:(1-1.5):(1-1.5), and the mass ratio of nano-zirconium dioxide and silane-modified light stabilizer is 1:(3-5).

8. The high hardness pet resistant flexible optical window film prepared by the method of any one of claims 1-7, wherein, The thickness of the substrate layer is 50-120μm; the adhesive is an acrylate adhesive, and the coating thickness is 5-10μm; and the thickness of the scratch-resistant and wear-resistant coating is 10-20μm.

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