Photochromic polyester film as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of photochromic films, and particularly discloses a photochromic polyester film as well as a preparation method and application thereof. The photochromic polyester film provided by the invention contains spiropyrane dye, and under ultraviolet irradiation, the transmittance of the film to visible light and near-infrared light is reduced, and the color of the film is darkened; and after the ultraviolet light is removed, the transmissivity of the visible light and the near-infrared light is recovered, and the color of the film disappears. Therefore, the polyester film has good photochromic performance. Besides, the composition and the structure of the film are improved by adjusting the preparation process of the photochromic polyester film, the obtained film material not only can perform reversible color development along with the change of illumination, but also has the advantages of high color change reaction rate, good color change stability and the like, and meanwhile, the polyester film is endowed with good opening property, thermal stability and fatigue resistance; the composite film is suitable for preparing protective covers, warning boards, automobile glass window films, building glass window films and the like, and has good application prospects and high economic value.

Description

Technical Field

[0001] The invention belongs to the technical field of photochromic films, and in particular relates to a photochromic polyester film and a preparation method and application thereof. Background Art

[0002] Photochromic film refers to a film material that can undergo a specific chemical reaction under the irradiation of light of a certain wavelength, causing its absorption spectrum to change significantly, and can restore its original absorption spectrum under the irradiation of light of another wavelength or the action of heat.

[0003] Photochromic glass film refers to a glass film that changes color under light and reversibly returns to its original color when the light disappears. Photochromic glass films include inorganic photochromic films and organic photochromic films. Inorganic photochromic glass films, such as nano WO3 films, can be prepared by chemical vapor deposition, electrodeposition, sputtering, etc. Organic photochromic glass films mostly use photochromic dyes such as spiropyran, naphthopyran, and azo, and can be prepared by spin coating, spray coating, etc.

[0004] At present, photochromic polyester glass films often have problems such as insufficient regulation of light transmittance, poor color change stability, poor thermal stability, and easy shedding of color-changing materials, which cannot meet the market demand for high-quality products. To solve this problem, Chinese patent CN111452439B provides a stimulus-responsive multifunctional polyester film, including a stimulus-responsive layer, a wear-resistant layer, a waterproof layer, an antistatic layer, a PET base layer, an adhesive layer, a first thermal insulation layer, a core layer, and a second thermal insulation layer arranged from top to bottom. The preparation method thereof includes: A. Preparation of the film body: Extrusion is used to make a thick sheet, and then biaxial stretching is performed to make the film body. The film body includes a wear-resistant layer, a waterproof layer, an antistatic layer, a PET base layer, an adhesive layer, a first thermal insulation layer, a core layer, and a second thermal insulation layer from top to bottom; B. , the stimulus response solution is evenly coated on the main body of the film by an offline coating device to form a stimulus response layer. After 60 seconds of ultraviolet irradiation, the color-changing film gradually changes from non-transparent to dark green, and the degree of color change deepens as the irradiation time increases; wherein, the preparation of the stimulus response solution includes: taking 50mL of deionized water and placing it in a beaker and heating it to 60°C in a water bath, adding 0-3.0g of triethylene glycol and 2.0-2.5g of gelatin, stirring until completely dissolved, cooling to 30°C and continuing to stir, and then adding 0.5-1.5g of ammonium molybdate and stirring to dissolve, and removing bubbles to obtain a stimulus response solution. The polyester film provided by this patent has thermal insulation and photochromic properties, but its structure is complex, and offline coating has certain restrictions on the width of the produced film, and the preparation cost is relatively high. Summary of the invention

[0005] 1. Technical issues to be resolved

[0006] The technical problem to be solved by the present invention is to provide a photochromic polyester film and a preparation method thereof, so as to overcome the problems of the existing polyester film such as poor regulation of light transmittance, poor color change stability, poor thermal stability, and easy shedding of the color-changing material.

[0007] The photochromic polyester film provided by the present invention has a reduced transmittance of visible light and near-infrared light under ultraviolet light irradiation, and the color of the film becomes darker; after the ultraviolet light is removed, the transmittance of visible light and near-infrared light is restored, and the color of the film disappears. At the same time, the photochromic polyester film provided by the present invention also has good opening, thermal stability and aging resistance.

[0008] (II) Technical solution

[0009] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0010] A photochromic polyester film is prepared by using a photochromic polyester slice and a bright polyester slice as raw materials and adopting a biaxial stretching process;

[0011] The photochromic polyester chips are prepared by esterification and polycondensation reaction with purified terephthalic acid, ethylene glycol, organic photochromic agent suspension and light stabilizer as raw materials under the action of a catalyst;

[0012] The organic photochromic agent in the organic photochromic agent suspension is composed of a spiropyran photochromic dye as a core material and an acrylate prepared by a reaction monomer containing methyl methacrylate under the action of an initiator as a shell material.

[0013] As a preferred embodiment of the present invention, the mass ratio of the photochromic polyester chips to the glossy polyester chips is 1-2:2-3.

[0014] Specifically, the bright polyester chips are commercially available products, for example, FG601 and FG604 film-grade polyester chips produced by Yizheng Chemical Fiber.

[0015] As a preferred embodiment of the present invention, the preparation of the photochromic polyester film includes the steps of feeding, melt extrusion, film casting, longitudinal stretching, transverse stretching, traction and winding, slitting and packaging.

[0016] Specifically, the temperature of the melt extrusion is 250-300°C.

[0017] Specifically, the cold drum temperature of the cast sheet is 18-40°C.

[0018] Specifically, the technical parameters of the longitudinal stretching are: preheating zone temperature 50-100° C., stretching zone temperature 80-125° C., cooling zone temperature 20-50° C., and stretching ratio 2-6 times.

[0019] Specifically, the technical parameters of the transverse stretching are: preheating zone temperature 80-120°C, stretching zone temperature 90-130°C, shaping zone temperature 200-250°C, cooling zone temperature 30-105°C, and stretching ratio 3-6 times.

[0020] As a preferred embodiment of the present invention, the mass ratio of purified terephthalic acid to ethylene glycol is 3-5:1-1.5.

[0021] As a preferred embodiment of the present invention, the mass ratio of the purified terephthalic acid to the organic photochromic agent suspension is 15-25:2-4.

[0022] As a preferred embodiment of the present invention, the mass ratio of purified terephthalic acid to light stabilizer is 3000-5000:1-10.

[0023] Specifically, the light stabilizer includes but is not limited to ultraviolet absorbers (such as UV-327, UV-328 and other benzotriazole ultraviolet absorbers), light shielding agents (such as carbon black, zinc oxide, titanium dioxide and other inorganic fillers), hindered amine light stabilizers, quenchers, etc.

[0024] As a preferred embodiment of the present invention, as a preferred embodiment of the present invention, the mass ratio of purified terephthalic acid to catalyst is 3000-5000:1-3.

[0025] Specifically, the catalyst is a mixture of calcium acetate or magnesium acetate and titanium trioxide or antimony glycolate, such as a mixed catalyst composed of calcium acetate and titanium trioxide.

[0026] Specifically, the mass ratio of calcium acetate or magnesium acetate to titanium oxide or antimony glycolate in the mixture is 2-7:12-25.

[0027] As a preferred embodiment of the present invention, the temperature of the esterification reaction is 200-250° C., and the reaction is stopped when the water output reaches more than 95% of the theoretical water output.

[0028] As a preferred embodiment of the present invention, the temperature of the polycondensation reaction is 250-300° C., and the reaction time is 1-2 hours. After the reaction is completed, the photochromic polyester chips are obtained by melt extrusion, granulation and drying.

[0029] As a preferred embodiment of the present invention, the raw materials for preparing the organic photochromic agent suspension include an organic photochromic agent, ethylene glycol and a titanate coupling agent, and the mass ratio of the organic photochromic agent to the ethylene glycol is 1:2-10. The amount of the titanate coupling agent accounts for 1%-10% of the total mass of the reaction system (i.e., the total mass of the organic photochromic agent, ethylene glycol and the titanate coupling agent).

[0030] Specifically, the preparation method of the organic photochromic agent suspension is as follows: the organic photochromic agent is mixed and dispersed with ethylene glycol, a titanate coupling agent is added, and the mixture is stirred and mixed for 1-2 hours, and then ultrasonically dispersed for 30-60 minutes to obtain the organic photochromic agent suspension. The ultrasonic power of the ultrasonic dispersion is 1000-3000W, and the ultrasonic frequency is 18-20kHz. Through the ethylene glycol pre-dispersion and ultrasonic dispersion treatment, powder agglomeration can be effectively avoided to affect the quality of the finished product.

[0031] Specifically, the titanate coupling agent includes but is not limited to one or more of di(triethanolamine) diisopropyl titanate (HY-1803, CAS: 36673-16-2), triisostearate isopropyl titanate (CAS: 61417-49-0), titanate coupling agent 311 (CAS: 65467-75-6), and the like.

[0032] As a preferred embodiment of the present invention, the spiropyran photochromic dye includes but is not limited to one or more of spiro[1,3,3-trimethylindole-chroman](CAS: 1485-92-3), spiro[1,3,3-trimethylindole-(6'-bromochroman)](CAS: 16650-14-9), spiro[1,3,3-trimethylindole-B-chroman](CAS: 1592-43-4), etc.

[0033] Specifically, the mass ratio of the spiropyran photochromic dye to the methyl methacrylate in the reaction monomer is 1-5:50-250.

[0034] As a preferred embodiment of the present invention, the reactive monomers include a main monomer and a functional monomer, wherein the main monomer includes but is not limited to methyl methacrylate (MMA), and the functional monomer includes but is not limited to pentaerythritol triacrylate (PETA).

[0035] Specifically, the mass ratio of methyl methacrylate to pentaerythritol triacrylate is 50-250:1-25.

[0036] As a preferred embodiment of the present invention, the initiator includes but is not limited to azobisisobutyronitrile (AIBN).

[0037] Specifically, the amount of the initiator added is 0.5%-2% of the mass of the reaction monomers.

[0038] As a preferred embodiment of the present invention, the preparation method of the organic photochromic agent includes: mixing a spiropyran photochromic dye with n-octane bromide to obtain a dye solution; mixing the dye solution with an aqueous solution of sodium dodecyl sulfate, adding a reaction monomer (including a main monomer and a functional monomer) and an initiator, and polymerizing at 70-90° C. for 6-10 hours. After the reaction is completed, the reaction product is separated, washed, and dried to obtain an organic photochromic agent.

[0039] Specifically, the mass ratio of the spiropyran photochromic dye to n-octane bromide is 1-5:100-500.

[0040] Specifically, the mass ratio of the dye solution to the aqueous solution of sodium dodecyl sulfate is 100:0.5-5 (sodium dodecyl sulfate, as a dispersion stabilizer, can form a protective film on the surface of the particles to prevent them from sticking to each other). The concentration of the aqueous solution of sodium dodecyl sulfate is 0.5%-2% (w / v).

[0041] A method for preparing a photochromic polyester film comprises the following steps:

[0042] (1) Preparation of organic photochromic agents

[0043] The dye solution containing the spiropyran photochromic dye is mixed with an aqueous solution of sodium dodecyl sulfate, a reaction monomer containing methyl methacrylate and an initiator are added, and a polymerization reaction is carried out at 70-90° C. for 6-10 hours to prepare an organic photochromic agent;

[0044] (2) Preparation of organic photochromic agent suspension

[0045] The organic photochromic agent is mixed and dispersed with ethylene glycol, a titanate coupling agent is added, and then ultrasonically dispersed for 30-60 minutes to prepare an organic photochromic agent suspension;

[0046] (3) Preparation of photochromic polyester chips

[0047] The purified terephthalic acid, ethylene glycol, organic photochromic agent suspension, light stabilizer and catalyst are mixed, and an esterification reaction is carried out at 200-250° C. After the reaction is completed, the temperature is raised to 250-300° C. for polycondensation reaction to obtain a photochromic polyester chip;

[0048] (4) Preparation of photochromic polyester film

[0049] The photochromic polyester slices are mixed with the bright polyester slices, melt-extruded and then cast, and the photochromic polyester film is prepared by biaxial stretching process.

[0050] As a preferred embodiment of the present invention, in step (1), the spiropyran photochromic dye includes but is not limited to one or more of spiro[1,3,3-trimethylindole-chroman](CAS:1485-92-3), spiro[1,3,3-trimethylindole-(6'-bromochroman)](CAS:16650-14-9), spiro[1,3,3-trimethylindole-B-chroman](CAS:1592-43-4), etc.

[0051] Specifically, the spiropyran photochromic dye is mixed with n-octane bromide to obtain a dye solution. The mass ratio of the spiropyran photochromic dye to n-octane bromide is 1-5:100-500.

[0052] As a preferred embodiment of the present invention, in step (1), the mass ratio of the dye solution to the aqueous solution of sodium dodecyl sulfate is 100:0.5-5. The concentration of the aqueous solution of sodium dodecyl sulfate is 0.5%-2% (w / v).

[0053] As a preferred embodiment of the present invention, in step (1), the reaction monomers include a main monomer methyl methacrylate (MMA) and a functional monomer, and the functional monomer includes but is not limited to pentaerythritol triacrylate (PETA).

[0054] Specifically, the mass ratio of the main monomer methyl methacrylate to the functional monomer pentaerythritol triacrylate is 50-250:1-25.

[0055] Specifically, the mass ratio of the spiropyran photochromic dye to methyl methacrylate is 1-5:50-250.

[0056] As a preferred embodiment of the present invention, in step (1), the initiator includes but is not limited to azobisisobutyronitrile (AIBN).

[0057] Specifically, the amount of the initiator added is 0.5%-2% of the mass of the reaction monomers.

[0058] As a preferred embodiment of the present invention, in step (1), the polymerization reaction is: first reacting at 70-75°C for 3-5h, and then reacting at 80-90°C for 3-5h. After the reaction is completed, the reaction product is separated (by centrifugation), washed and dried to obtain an organic photochromic agent.

[0059] As a preferred embodiment of the present invention, in step (2), the mass ratio of the organic photochromic agent to ethylene glycol is 1:2-10. The amount of the titanate coupling agent accounts for 1%-10% of the total mass of the reaction system (i.e. the total mass of the organic photochromic agent, ethylene glycol and titanate coupling agent).

[0060] Specifically, the titanate coupling agent includes but is not limited to one or more of di(triethanolamine)titanate diisopropyl ester (HY-1803, CAS: 36673-16-2), triisostearate titanate isopropyl ester (CAS: 61417-49-0), titanate coupling agent 311 (CAS: 65467-75-6), etc. After adding the titanate coupling agent, stir and mix for 1-2 hours, and then disperse by ultrasonication.

[0061] As a preferred embodiment of the present invention, in step (2), the ultrasonic power of the ultrasonic dispersion is 1000-3000W, and the ultrasonic frequency is 18-20kHz.

[0062] As a preferred embodiment of the present invention, in step (3), the mass ratio of purified terephthalic acid to ethylene glycol is 3-5:1-1.5.

[0063] As a preferred embodiment of the present invention, in step (3), the mass ratio of the purified terephthalic acid to the organic photochromic agent suspension is 15-25:2-4.

[0064] As a preferred embodiment of the present invention, in step (3), the mass ratio of purified terephthalic acid to light stabilizer is 3000-5000:1-10.

[0065] Specifically, the light stabilizer includes but is not limited to ultraviolet absorbers (such as UV-327, UV-328 and other benzotriazole ultraviolet absorbers), light shielding agents (such as carbon black, zinc oxide, titanium dioxide and other inorganic fillers), hindered amine light stabilizers, quenchers, etc.

[0066] As a preferred embodiment of the present invention, in step (3), the mass ratio of purified terephthalic acid to catalyst is 3000-5000:1-3.

[0067] Specifically, the catalyst is a mixture of calcium acetate or magnesium acetate and titanium trioxide or antimony glycolate, such as a mixed catalyst composed of calcium acetate and titanium trioxide.

[0068] Specifically, the mass ratio of calcium acetate or magnesium acetate to titanium oxide or antimony glycolate in the mixture is 2-7:12-25.

[0069] As a preferred embodiment of the present invention, in step (3), the esterification reaction is stopped when the water output reaches more than 95% of the theoretical water output.

[0070] As a preferred embodiment of the present invention, in step (3), the polycondensation reaction time is 1-2 hours. After the reaction is completed, the photochromic polyester chips are obtained by melt extrusion, granulation and drying.

[0071] As a preferred embodiment of the present invention, in step (4), the mass ratio of the photochromic polyester chips to the glossy polyester chips is 1-2:2-3.

[0072] Specifically, the bright polyester chips are commercially available products, for example, FG601 and FG604 film-grade polyester chips produced by Yizheng Chemical Fiber.

[0073] As a preferred embodiment of the present invention, in step (4), the temperature of the melt extrusion is 250-300°C. The cold drum temperature of the cast sheet is 18-40°C.

[0074] As a preferred embodiment of the present invention, in step (4), the biaxial stretching process includes longitudinal stretching and transverse stretching. The technical parameters of the longitudinal stretching are: preheating zone temperature 50-100°C, stretching zone temperature 80-125°C, cooling zone temperature 20-50°C, and stretching ratio 2-6 times. The technical parameters of the transverse stretching are: preheating zone temperature 80-120°C, stretching zone temperature 90-130°C, shaping zone temperature 200-250°C, cooling zone temperature 30-105°C, and stretching ratio 3-6 times. After biaxial stretching, the photochromic polyester film is obtained through traction, winding, slitting and packaging processes.

[0075] A photochromic polyester film is used in the preparation of protective covers, warning signs, automobile glass window films, architectural glass window films, etc.

[0076] (III) Beneficial effects

[0077] It is known that under ultraviolet light, the CO bond in the colorless spiropyran structure breaks and the ring opens, the molecule rotates locally and forms a coplanar merocyanine structure with indole, thus showing color. After the ultraviolet light is removed, under the action of visible light, the open ring body returns to the spiro structure without showing color. Since the CO bond breaks in an extremely short time, the color change speed is extremely fast, and the merocyanine structure will automatically turn into a non-coloring spiro structure after being left at room temperature for several minutes or even hours.

[0078] The photochromic polyester film provided by the present invention contains spiropyran dyes. Under ultraviolet light irradiation, the transmittance of the film to visible light and near-infrared light decreases, and the color of the film becomes darker; after the ultraviolet light is removed, the transmittance of visible light and near-infrared light is restored, and the color of the film disappears. Therefore, the polyester film has good photochromic properties. In addition, the present invention improves the film composition and structure by adjusting the film preparation process. First, the spiropyran photochromic dye is used as the core material, and an organic photochromic agent with a core-shell (acrylate) structure is prepared by monomer polymerization reaction, and then the organic photochromic agent is prepared into a suspension with good dispersibility, and then mixed with purified terephthalic acid and ethylene glycol, and photochromic polyester slices are prepared through esterification and polycondensation reaction, and then the slices are melted with the bright polyester slice mixture, and the photochromic polyester film is prepared through a biaxial stretching process. The obtained film material can not only reversibly display color with changes in light, but also has the advantages of fast color change reaction rate and good color change stability. At the same time, it also gives the polyester film good openability, thermal stability and aging resistance. It is suitable for the preparation of protective covers, warning signs, automobile glass window films, architectural glass window films, etc., and has good application prospects and high economic value.

[0079] The preparation method of the photochromic polyester film provided by the invention has reasonable process, strong operability and is easy to carry out industrial production. DETAILED DESCRIPTION

[0080] The technical scheme of the present invention will be clearly and completely described below in conjunction with specific embodiments and experimental examples. Those skilled in the art should understand that the following embodiments and experimental examples are only used to illustrate the technical scheme and technical effects of the present invention and should not be regarded as any limitation on the protection scope of the present invention. Based on the following embodiments, other technical schemes obtained by ordinary technicians in the field without paying creative labor, such as technical schemes obtained after modification, deformation or simple replacement, all belong to the protection scope of the present invention.

[0081] The raw materials, reagents, equipment, etc. used in the embodiments and experimental examples are all commercially available products unless otherwise specified. Among them, spiro[1,3,3-trimethylindole-(6'-bromobenzodihydropyran)] (CAS: 16650-14-9) was purchased from Shanghai Yuanye Biotechnology Co., Ltd. Isopropyl titanate triisostearate (CAS: 61417-49-0) was purchased from Darli Chemical. UV-327 (2-(3,5-di-tert-butyl-2-hydroxyphenyl)-5-chlorobenzotriazole, CAS: 3864-99-1) was purchased from Dixin Chemical. The glossy polyester chips were purchased from Yizheng Chemical Fiber, which are FG601 or FG604 film-grade polyester chips with good brightness and transparency, high cleanliness, few impurities, and excellent film-forming properties.

[0082] The methods used in the embodiments and experimental examples are conventional methods unless otherwise specified.

[0083] The terms and abbreviations used in the embodiments and experimental examples have common meanings in the art.

[0084] Example 1

[0085] This embodiment provides a photochromic polyester film, which is prepared by a method comprising the following steps:

[0086] (1) Preparation of organic photochromic agents

[0087] 2 g of spiropyran photochromic dye spiro[1,3,3-trimethylindole-(6'-bromochroman)] (CAS: 16650-14-9) was dissolved in 200 g of octane bromide to obtain a dye solution; 100 g of the dye solution and 1 g of a 0.5% aqueous solution of sodium dodecyl sulfate were vigorously stirred at a speed of 1000 r / min for 20 min; 100 g of methyl methacrylate (MMA) and 2 g of pentaerythritol triacrylate (PETA) were ultrasonically dispersed for 30 min (ultrasonic power 1500 W, ultrasonic frequency The dispersed reaction monomers are added to the dye solution containing spiropyran, and stirred for 30 minutes in a constant temperature water bath at 40°C and a speed of 1000r / min. Then, 1% of the mass of the reaction monomer as initiator azobisisobutyronitrile (AIBN) is added, and the water bath temperature is adjusted to 75°C, and the stirring speed is reduced to 750r / min. The reaction is carried out for 4 hours, and then the water bath temperature is increased to 80°C and the reaction is carried out for 4 hours. The reaction product is centrifuged for 15 minutes, washed with ethanol 3 times, and vacuum dried for 24 hours to obtain an organic photochromic agent containing photochromic spiropyran and PMMA.

[0088] (2) Preparation of organic photochromic agent suspension

[0089] The organic photochromic agent and ethylene glycol were mixed and pre-dispersed in a mass ratio of 1:2, and then 1% of the volume of the mixture was added as a titanate coupling agent isopropyl triisostearate titanate (CAS: 61417-49-0), and magnetic stirring was performed at room temperature for 1.5 hours, and then ultrasonic dispersion treatment was performed for 30 minutes (ultrasonic power 1500 W, ultrasonic frequency 18 kHz) to obtain an organic photochromic agent suspension.

[0090] (3) Preparation of photochromic polyester chips

[0091] In a 20L general polymerization reactor, 3000g of purified terephthalic acid, 1000g of ethylene glycol, 1g of a mixed catalyst of calcium acetate and titanium oxide (the mass ratio of the two is 1:6), 400g of an organic photochromic agent suspension and 1g of a light stabilizer UV-327 (2-(3,5-di-tert-butyl-2-hydroxyphenyl)-5-chlorobenzotriazole, CAS: 3864-99-1) were added, and an esterification reaction was carried out at 200°C. The reaction was stopped when the water output reached 98% of the theoretical water output. The temperature was then raised to 250°C for a condensation reaction. The reaction time was 1h. Finally, the photochromic polyester chips were obtained by melt extrusion at 275°C, granulation and drying.

[0092] (4) Preparation of photochromic polyester film

[0093] 500 g of photochromic polyester chips were blended with 1000 g of bright polyester chips (FG604 film-grade polyester chips from Yizheng Chemical Fiber), dried at 65° C. for 5 h, and then melt-extruded at 275° C. through a single-screw extruder, and then sequentially passed through cast film (cold drum temperature 26° C.), longitudinal stretching (preheating zone temperature 85° C., stretching zone temperature 105° C., cooling zone temperature 30° C., stretching ratio 4 times), transverse stretching (preheating zone temperature 106° C., stretching zone temperature 118° C., shaping zone temperature 242° C., cooling zone temperature 90° C., stretching ratio 4 times), traction and winding, slitting and packaging processes to obtain a photochromic polyester film.

[0094] This embodiment also provides an application of a photochromic polyester film in the preparation of a protective cover, a warning sign, a car glass window film or a building glass window film.

[0095] Example 2

[0096] This embodiment provides a photochromic polyester film, which is prepared by a method comprising the following steps:

[0097] (1) Preparation of organic photochromic agents

[0098] 5 g of spiropyran photochromic dye spiro[1,3,3-trimethylindole-(6'-bromochroman)] (CAS: 16650-14-9) was dissolved in 500 g of n-octane bromide to obtain a dye solution; 300 g of the dye solution and 6 g of a 1% sodium dodecyl sulfate aqueous solution were vigorously stirred at a speed of 1000 r / min for 20 min; 300 g of methyl methacrylate (MMA) and 25 g of pentaerythritol triacrylate (PETA) were ultrasonically dispersed for 30 min (ultrasonic power 1500 W, ultrasonic frequency 200 Hz). The dispersed reaction monomers are added to the dye solution containing spiropyran, and stirred for 30 minutes in a constant temperature water bath at 40°C and a speed of 1000 r / min. Then, 1% of the mass of the reaction monomer as an initiator azobisisobutyronitrile (AIBN) is added, and the water bath temperature is adjusted to 75°C, and the stirring speed is reduced to 800 r / min. The reaction is carried out for 4 hours, and then the water bath temperature is increased to 80°C and the reaction is carried out for 4 hours. The reaction product is centrifuged for 15 minutes, washed with ethanol three times, and vacuum dried for 24 hours to obtain an organic photochromic agent containing photochromic spiropyran and PMMA.

[0099] (2) Preparation of organic photochromic agent suspension

[0100] The organic photochromic agent and ethylene glycol were mixed and pre-dispersed in a mass ratio of 1:5, and then 5% of the volume of the mixture was added as a titanate coupling agent isopropyl triisostearate titanate (CAS: 61417-49-0), and magnetic stirring was performed at room temperature for 1.5 hours, and then ultrasonic dispersion treatment was performed for 30 minutes (ultrasonic power 1500 W, ultrasonic frequency 18 kHz) to obtain an organic photochromic agent suspension.

[0101] (3) Preparation of photochromic polyester chips

[0102] In a 20L general polymerization reactor, 4000g of purified terephthalic acid, 1200g of ethylene glycol, 2g of a mixed catalyst of calcium acetate and titanium oxide (the mass ratio of the two is 1:6.5), 600g of an organic photochromic agent suspension and 5g of a light stabilizer UV-327 (2-(3,5-di-tert-butyl-2-hydroxyphenyl)-5-chlorobenzotriazole, CAS: 3864-99-1) were added, and an esterification reaction was carried out at 200°C. The reaction was stopped when the water output reached 98% of the theoretical water output. The temperature was then raised to 250°C for a condensation reaction. The reaction time was 2h. Finally, the photochromic polyester chips were obtained by melt extrusion at 275°C, granulation and drying.

[0103] (4) Preparation of photochromic polyester film

[0104] 800g of photochromic polyester chips were blended with 1200g of bright polyester chips (FG604 film-grade polyester chips from Yizheng Chemical Fiber), dried at 70°C for 6h, and then melt-extruded at 278°C through a single-screw extruder, and then successively passed through cast film (cold drum temperature 26°C), longitudinal stretching (preheating zone temperature 85°C, stretching zone temperature 108°C, cooling zone temperature 30°C, stretching ratio 4 times), transverse stretching (preheating zone temperature 106°C, stretching zone temperature 118°C, shaping zone temperature 242°C, cooling zone temperature 90°C, stretching ratio 4 times), traction and winding, slitting and packaging processes to obtain a photochromic polyester film.

[0105] This embodiment also provides an application of a photochromic polyester film in the preparation of a protective cover, a warning sign, a car glass window film or a building glass window film.

[0106] Example 3

[0107] This embodiment provides a photochromic polyester film, which is prepared by a method comprising the following steps:

[0108] (1) Preparation of organic photochromic agents

[0109] 10 g of spiropyran photochromic dye spiro[1,3,3-trimethylindole-(6'-bromochroman)] (CAS: 16650-14-9) was dissolved in 1000 g of n-octane bromide to obtain a dye solution; 500 g of the dye solution and 15 g of a 2% sodium dodecyl sulfate aqueous solution were vigorously stirred at a speed of 1000 r / min for 20 min; 500 g of methyl methacrylate (MMA) and 50 g of pentaerythritol triacrylate (PETA) were ultrasonically dispersed for 30 min (ultrasonic power 1500 W, ultrasonic The dispersed reaction monomers are added to the dye solution containing spiropyran, and stirred for 30 minutes in a constant temperature water bath at 40°C and a speed of 1000 r / min. Then, 1% of the mass of the reaction monomer as an initiator azobisisobutyronitrile (AIBN) is added, and the water bath temperature is adjusted to 75°C, and the stirring speed is reduced to 800 r / min. The reaction is carried out for 4 hours, and then the water bath temperature is increased to 80°C and the reaction is carried out for 4 hours. The reaction product is centrifuged for 15 minutes, washed with ethanol 3 times, and vacuum dried for 24 hours to obtain an organic photochromic agent containing photochromic spiropyran and PMMA.

[0110] (2) Preparation of organic photochromic agent suspension

[0111] The organic photochromic agent and ethylene glycol were mixed and pre-dispersed in a mass ratio of 1:10, and then 10% of the volume of the mixture was added as a titanate coupling agent isopropyl triisostearate titanate (CAS: 61417-49-0), and magnetic stirring was performed at room temperature for 1.5 hours, and then ultrasonic dispersion treatment was performed for 30 minutes (ultrasonic power 1500 W, ultrasonic frequency 18 kHz) to obtain an organic photochromic agent suspension.

[0112] (3) Preparation of photochromic polyester chips

[0113] In a 20L general polymerization reactor, 5000g of purified terephthalic acid, 1500g of ethylene glycol, 3g of magnesium acetate and ethylene glycol antimony mixed catalyst (the mass ratio of the two is 1:5), 800g of organic photochromic agent suspension and 5g of light stabilizer UV-327 (2-(3,5-di-tert-butyl-2-hydroxyphenyl)-5-chlorobenzotriazole, CAS: 3864-99-1) were added, and esterification reaction was carried out at 250°C. The reaction was stopped when the water output reached 98% of the theoretical water output. The temperature was then raised to 300°C for polycondensation reaction. The reaction time was 1.5h. Finally, the photochromic polyester chips were obtained by melt extrusion at 275°C, granulation and drying.

[0114] (4) Preparation of photochromic polyester film

[0115] 1000g of photochromic polyester chips were blended with 1500g of bright polyester chips (FG601 film-grade polyester chips from Yizheng Chemical Fiber), dried at 80°C for 5h, and then melt-extruded at 278°C through a single-screw extruder. The film was then subjected to cast film (cold drum temperature 26°C), longitudinal stretching (preheating zone temperature 85°C, stretching zone temperature 108°C, cooling zone temperature 30°C, and stretching ratio 4 times), transverse stretching (preheating zone temperature 106°C, stretching zone temperature 118°C, shaping zone temperature 242°C, cooling zone temperature 90°C, and stretching ratio 4 times), traction and winding, slitting and packaging steps to obtain a photochromic polyester film.

[0116] This embodiment also provides an application of a photochromic polyester film in the preparation of a protective cover, a warning sign, a car glass window film or a building glass window film.

[0117] Experimental example

[0118] 1. Photochromic performance test

[0119] Experimental method: Take the photochromic polyester film prepared in Example 2, and use a spectrophotometer to measure the light transmittance of the film before, after and after being irradiated with ultraviolet light, with a test wavelength of 200-600nm. The experimental results are shown in Table 1 below.

[0120] Table 1 Light transmittance of photochromic polyester film

[0121]

[0122] The experimental results showed that under ultraviolet light irradiation, the polyester film underwent a significant color change within 5 seconds, and the color basically reached saturation in about 30 seconds, indicating that the film material has good photochromic properties.

[0123] 2. Opening test

[0124] Experimental method: The photochromic polyester film prepared in Example 2 was taken and the opening property of the film was evaluated by testing the friction coefficient according to the ASTM-D1894 standard. The experimental results are shown in Table 2 below.

[0125] Table 2 Opening test results of photochromic polyester film

[0126]

[0127] The experimental results show that the dynamic and static friction coefficients of the polyester film are both ≤0.42, indicating that the film material has good opening properties.

[0128] 3. Thermal stability test

[0129] Experimental method: The photochromic polyester film prepared in Example 2 was subjected to the ASTM D-1204 standard. The experimental results are shown in Table 3 below.

[0130] Table 3 Thermal stability test results of photochromic polyester film

[0131]

[0132] The experimental results show that the polyester film has good thermal stability and excellent mechanical properties.

[0133] 4. Fatigue resistance test

[0134] Experimental method: Take the photochromic polyester film prepared in Example 2, use ultraviolet light to intermittently irradiate the film for 20 cycles, and test the change of its absorbance to characterize the light fatigue resistance of the film. The experimental results are shown in Table 4 below.

[0135] Table 4 Fatigue resistance test results of photochromic polyester film

[0136] Cycle times 5 10 15 20 UV irradiation ≥0.62 ≥0.6 ≥0.6 ≥0.59 Dark Processing ≤0.16 ≤0.16 ≤0.16 ≤0.15

[0137] The experimental results show that polyester film has good light fatigue resistance.

[0138] Conclusion: From the above experimental results, it can be seen that the polyester film provided by the present invention has excellent photochromic properties, changes color quickly under ultraviolet light, maintains a good color change effect after multiple irradiations, and has excellent color change stability and thermal stability. At the same time, the polyester film also has good opening and fatigue resistance.

[0139] Although the technical scheme and technical effects of the present invention have been described in detail above by means of general description, specific embodiments and experimental examples, for those skilled in the art, any modification, replacement or improvement made without departing from the spirit of the present invention shall fall within the protection scope of the present invention.

Claims

1. A photochromic polyester film, characterized in that: The polyester film is made of photochromic polyester chips and bright polyester chips by adopting a biaxial stretching process; The photochromic polyester chips are prepared by esterification and polycondensation reaction with purified terephthalic acid, ethylene glycol, organic photochromic agent suspension and light stabilizer as raw materials under the action of a catalyst; The organic photochromic agent in the organic photochromic agent suspension is composed of a spiropyran photochromic dye as a core material and an acrylate prepared by a reaction monomer containing methyl methacrylate under the action of an initiator as a shell material.

2. The photochromic polyester film according to claim 1, characterized in that: The mass ratio of the photochromic polyester slice to the glossy polyester slice is 1-2:2-3.

3. The photochromic polyester film according to claim 1, characterized in that: The mass ratio of purified terephthalic acid to ethylene glycol is 3-5:1-1.5; And / or, the mass ratio of the purified terephthalic acid to the organic photochromic agent suspension is 15-25:2-4; And / or, the mass ratio of the purified terephthalic acid to the light stabilizer is 3000-5000:1-10; And / or, the mass ratio of purified terephthalic acid to catalyst is 3000-5000:1-3.

4. The photochromic polyester film according to claim 1, characterized in that: The raw materials for preparing the organic photochromic agent suspension include an organic photochromic agent, ethylene glycol and a titanate coupling agent; And / or, the mass ratio of the spiropyran photochromic dye to methyl methacrylate in the reaction monomer is 1-5:50-250.

5. A method for preparing a photochromic polyester film according to any one of claims 1 to 4, characterized in that: The preparation method comprises the following steps: (1) Preparation of organic photochromic agents The dye solution containing the spiropyran photochromic dye is mixed with an aqueous solution of sodium dodecyl sulfate, a reaction monomer containing methyl methacrylate and an initiator are added, and a polymerization reaction is carried out at 70-90° C. for 6-10 hours to prepare an organic photochromic agent; (2) Preparation of organic photochromic agent suspension The organic photochromic agent is mixed and dispersed with ethylene glycol, a titanate coupling agent is added, and then ultrasonically dispersed for 30-60 minutes to prepare an organic photochromic agent suspension; (3) Preparation of photochromic polyester chips The purified terephthalic acid, ethylene glycol, organic photochromic agent suspension, light stabilizer and catalyst are mixed, and an esterification reaction is carried out at 200-250° C. After the reaction is completed, the temperature is raised to 250-300° C. for polycondensation reaction to obtain a photochromic polyester chip; (4) Preparation of photochromic polyester film The photochromic polyester slices are mixed with the bright polyester slices, melt-extruded and then cast, and the photochromic polyester film is prepared by biaxial stretching process.

6. The method for preparing a photochromic polyester film according to claim 5, characterized in that: In step (1), the reaction monomers include a main monomer methyl methacrylate and a functional monomer, wherein the functional monomer includes but is not limited to pentaerythritol triacrylate; And / or, the mass ratio of the spiropyran photochromic dye to methyl methacrylate is 1-5:50-250; And or, the initiator includes but is not limited to azobisisobutyronitrile, and the amount of the initiator added is 0.5%-2% of the mass of the reaction monomer; And / or, the polymerization reaction is: first reacting at 70-75° C. for 3-5 hours, and then reacting at 80-90° C. for 3-5 hours.

7. The method for preparing a photochromic polyester film according to claim 5, characterized in that: In step (2), the mass ratio of the organic photochromic agent to ethylene glycol is 1:2-10; And / or, the amount of the titanate coupling agent used accounts for 1%-10% of the total mass of the reaction system; And / or, the ultrasonic power of the ultrasonic dispersion is 1000-3000W, and the ultrasonic frequency is 18-20kHz.

8. The method for preparing a photochromic polyester film according to claim 5, characterized in that: In step (3), the mass ratio of purified terephthalic acid to ethylene glycol is 3-5:1-1.5; And / or, the mass ratio of the purified terephthalic acid to the organic photochromic agent suspension is 15-25:2-4; And / or, the mass ratio of the purified terephthalic acid to the light stabilizer is 3000-5000:1-10; And / or, the mass ratio of purified terephthalic acid to catalyst is 3000-5000:1-3.

9. The method for preparing a photochromic polyester film according to claim 5, characterized in that: In step (4), the mass ratio of the photochromic polyester chips to the glossy polyester chips is 1-2:2-3.

10. Use of the photochromic polyester film according to any one of claims 1 to 4 in the preparation of protective covers, warning signs, automobile glass window films, and architectural glass window films.

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