A highly selective uv-absorbing film based on polyvinyl acetal and a method for its preparation

Abstract

This invention discloses a highly efficient selective UV-absorbing film based on polyvinyl acetal and its preparation method, belonging to the technical field of polymer functional membrane materials. The UV-absorbing film comprises the following components in parts by weight: 55-95 parts of matrix resin, 5-45 parts of plasticizer, 0.005-1.2 parts of core UV absorber, 0.01-0.3 parts of auxiliary UV absorber, 0.01-0.8 parts of composite antioxidant, 0.01-0.8 parts of light stabilizer, and 0.0025-0.0065 parts of metal ion additive. The core UV absorber is an alkyl-modified benzoxazinone compound, and the composite antioxidant is a combination of a hindered phenolic resin as the main antioxidant and a thiophosphate ester as the auxiliary antioxidant. This invention achieves highly efficient blocking of UV-B radiation and high transmittance of UV-A radiation. Simultaneously, the film material has advantages such as low initial yellowing, excellent long-term anti-yellowing performance, good thermal stability, good compatibility with the matrix, and no exudation. The present invention also provides a method for preparing the core UV absorber and a method for preparing the membrane, which are simple processes and suitable for industrial production.

Description

Technical Field

[0001] This invention belongs to the field of polymer functional membrane materials technology, specifically relating to a highly efficient selective UV absorption membrane based on polyvinyl acetal and its preparation method. Background Technology

[0002] Currently, polyvinyl butyral (PVB) films containing plasticizers are widely used as interlayer or encapsulation materials in fields such as composite glass and optoelectronic modules. To resist the aging and damage of materials caused by UV radiation, traditional PVB films often contain benzotriazole-type UV absorbers (such as Tinuvin 328 and Tinuvin 327). Although these absorbers can cover the entire UV-A and UV-B bands, they exhibit significant absorption in the visible light region (around 400nm), causing the film material to yellow easily and affecting the product's appearance and light transmittance.

[0003] With the diversification of application scenarios, some fields have put forward selective requirements for UV radiation transmittance: Greenhouse coverings: High UV-A (325-400nm) transmittance is required to ensure plant photosynthesis and insect pollination, while blocking UV-B (280-325nm) to prevent plant damage; Photovoltaic modules: Some photovoltaic cells are photosensitive in the 325-380nm wavelength range, requiring high UV-A transmittance to improve photoelectric conversion efficiency, and UV-B blocking to protect the cell components; Colorless window glass and furniture glass: High UV-A transmittance is required to present natural colors, while also being compatible with the use of UV-A curing adhesives; Bird protection window glass: Partial UV-A transmittance is required to create spectral contrast perceptible to birds, reducing the risk of collisions. However, existing technologies still have the following shortcomings: Benzotriazole-type UV absorbers: While offering full UV-A / UV-B blocking, they cannot meet the UV-A transmittance requirements of specific scenarios and easily cause yellowing of the membrane material. PVB membranes without UV absorbers: Excessively high UV-B transmittance leads to accelerated material aging, and traditional phenolic antioxidants (such as Irganox 1010 and 1076) are prone to decomposition and yellowing under UV radiation. Existing oxaloylaniline-type UV absorber-based antioxidant systems: These largely rely on bicyclic or monocyclic phenols, resulting in insufficient synergistic anti-aging properties under long-term high temperature and humidity conditions, and limited compatibility with some plasticizers. Single-type antioxidants: These struggle to simultaneously achieve thermal stability, anti-yellowing properties, and synergistic effects with UV absorbers, leading to significant performance degradation of the membrane material after long-term use. Existing benzoxazinone-type UV absorbers: Lacking targeted alkyl modification, they exhibit poor compatibility with PVB matrices and plasticizers, are prone to precipitation after long-term use, and their UV-B absorption efficiency needs improvement.

[0004] Therefore, developing a polyvinyl acetal film that can achieve high UV-A transmittance, efficient UV-B blocking, and also has low yellowing, high stability, and excellent compatibility is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a highly efficient selective UV absorber based on polyvinyl acetal and its preparation method. This invention achieves high efficiency in blocking UV-B (280-325nm) radiation and high transmittance in UV-A (325-400nm) radiation by selecting specific alkyl-modified benzoxazinone UV absorbers and working synergistically with composite antioxidants, light stabilizers and metal ion additives. At the same time, the film material has the advantages of low initial yellowness, excellent long-term anti-yellowing performance, good thermal stability, good compatibility with the matrix and no precipitation.

[0006] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a highly efficient selective UV absorber film based on polyvinyl acetal, comprising the following components in parts by weight: The composition includes 55-95 parts of matrix resin, 5-45 parts of plasticizer, 0.005-1.2 parts of core UV absorber, 0.01-0.3 parts of auxiliary UV absorber, 0.01-0.8 parts of composite antioxidant, 0.01-0.8 parts of light stabilizer, and 0.0025-0.0065 parts of metal ion additive.

[0007] Furthermore, the amount of matrix resin used is more preferably 65-85 parts, and most preferably 70-75 parts; The plasticizer is more preferably 15-30 parts, and most preferably 20-28 parts; The amount of the core UV absorber is more preferably 0.05-0.5 parts, and most preferably 0.08-0.4 parts; The amount of auxiliary UV absorber is more preferably 0.03-0.2 parts, and most preferably 0.05-0.15 parts; The preferred dosage of the compound antioxidant is 0.03-0.6 parts, and the most preferred dosage is 0.05-0.5 parts; The amount of light stabilizer used is more preferably 0.03-0.6 parts, and most preferably 0.05-0.4 parts; The amount of metal ion additive is more preferably 0.0030-0.0060 parts, and most preferably 0.0035-0.0055 parts.

[0008] Furthermore, the raw materials also include 0.002-0.1 parts of antistatic agent and 0.003-0.1 parts of adhesion modifier; The antistatic agent is selected from one or more of glyceryl monostearate, glyceryl distearate, polyethylene glycol fatty acid ester, sodium alkyl sulfonate, and alkyl betaine; The adhesive modifier is selected from one or more of maleic anhydride modified polyethylene, maleic anhydride modified polypropylene, acrylate modified polyethylene, and epoxy-modified polyethylene. Preferably, the matrix resin includes one or more of polyvinyl butyral, polyvinyl formal, polyvinyl propionate, and polyvinyl pentaldehyde.

[0009] Furthermore, the matrix resin is polyvinyl butyral; Preferably, the polyvinyl butyral is prepared from high-purity polyvinyl alcohol. The degree of polymerization of the high-purity polyvinyl alcohol is selected to be 1000-5000, more preferably 1500-4000, and most preferably 2000-3000; The degree of hydrolysis of polyvinyl alcohol is preferably ≥95 mol%, more preferably ≥98 mol%, and most preferably ≥99 mol%. The degree of acetalization of polyvinyl alcohol acetal is selected as 60-85 mol%, more preferably 65-80 mol%, and most preferably 70-75 mol%. The hydroxyl content of polyvinyl alcohol (i.e., the content of residual polyvinyl alcohol units) is selected to be 12-20 parts, more preferably 14-18 parts, and most preferably 15-17 parts; The polyvinyl acetate content is selected as ≤5 parts, more preferably ≤3 parts, most preferably ≤0.5 parts, and even more preferably ≤0.25 parts; The extinction of the 4% polyvinyl alcohol aqueous solution at 280 nm is preferably ≤0.5, more preferably ≤0.3, most preferably ≤0.2, and particularly preferably ≤0.1.

[0010] Preferably, the plasticizer comprises one or more of the following: diisononyl adipate (DINA), diisononyl 1,2-cyclohexanedicarboxylate (DINCH), triethylene glycol bis-2-ethylhexanoate (3G8), di-2-ethylhexyl sebacate (DOS), di-2-ethylhexyl adipate (DOA), dihexyl adipate (DHA), dibutyl sebacate (DBS), triethylene glycol bis-2-propylhexanoate, and di-2-butoxyethyl sebacate (DBES). More preferably, it is a combination of two or three of DINA, DINCH, and 3G8, and most preferably, it is a combination of DINA, DINCH, and 3G8 in a weight ratio of 2:1:1. The water content of the plasticizer is selected to be ≤0.1 wt%, more preferably ≤0.08 wt%, and most preferably ≤0.05 wt%; the acid value is selected to be ≤0.05 mgKOH / g, more preferably ≤0.03 mgKOH / g, and most preferably ≤0.01 mgKOH / g.

[0011] Preferably, the core UV absorber is an alkyl-modified benzoxazinone compound; The structural formula of the alkyl-modified benzoxazinone compound is: ; In the formula, R1 is selected from C4-C8 branched alkyl groups, more preferably C5-C7 branched alkyl groups, and most preferably isoamyl; R2 is selected from C2-C4 alkoxy groups, more preferably ethoxy or propoxy groups, and most preferably ethoxy.

[0012] The alkyl-modified benzoxazinone compound is 2,2'-methylenebis(4-tert-butyl-6-(2-ethoxy-4-isoamyl)benzoxazinone); The purity of the core UV absorber is selected to be ≥98%, more preferably ≥98.5%, and most preferably ≥99%; the thermal decomposition temperature is selected to be ≥270 °C, more preferably ≥280 °C, and most preferably ≥290 °C; the solubility in the plasticizer at 25 °C is selected to be ≥5 g / 100 g, more preferably ≥8 g / 100 g, and most preferably ≥10 g / 100 g; the absorption coefficient in the 280-325 nm wavelength band is selected to be ≥5000 L / (mol cm), more preferably ≥6000 L / (mol cm), and most preferably ≥7000 L / (mol cm); the absorption coefficient in the 350-400 nm wavelength band is selected to be ≤500 L / (mol cm), more preferably ≤400 L / (mol cm), and most preferably ≤300 L / (mol cm).

[0013] Furthermore, the preparation method of the alkyl-modified benzoxazinone compound is as follows: (1) Reaction principle Using 2-tert-butyl-4-isoamylphenol, ethoxyamine, and formaldehyde as raw materials, the target product is prepared through three steps of condensation - ring closure - alkylation. The reaction formula is as follows: 2-tert-butyl-4-isoamylphenol + ethoxyamine + formaldehyde + catalyst = alkyl-modified benzoxazinone + H2O.

[0014] (2) Raw material ratio (molar ratio) 2-tert-butyl-4-isopentylphenol:ethoxyamine:formaldehyde:catalyst = 1:(1.0-1.5):(1.2-1.8):(0.03-0.08), more preferably = 1:(1.1-1.3):(1.4-1.6):(0.04-0.06), and most preferably 1:1.2:1.5:0.05.

[0015] (3) Specific steps Condensation reaction: 2-tert-butyl-4-isopentylphenol (purity ≥99%) and ethoxyamine are added to a reaction vessel, and anhydrous ethanol is added as a solvent (solid-liquid ratio 1:3-1:7, g / mL, more preferably 1:4-1:6, most preferably 1:5). After stirring evenly, the temperature is raised to 45-55℃ (more preferably 48-52℃, most preferably 50℃), and 37% formaldehyde aqueous solution is added dropwise over a time of 0.5-1.5h (more preferably 0.8-1.2h, most preferably 1h). The reaction is maintained at this temperature for 1.5-2.5h (more preferably 1.8-2.2h, most preferably 2h) to obtain the intermediate (N-ethoxy-2-hydroxy-3-tert-butyl-5-isopentylanisole). Ring-closing reaction: Add 0.3-0.7 mol / L hydrochloric acid solution (more preferably 0.4-0.6 mol / L, most preferably 0.5 mol / L) to the reaction vessel to adjust the pH to 2.5-4.5 (more preferably 3-4, most preferably 3.5), raise the temperature to 75-85℃ (more preferably 78-82℃, most preferably 80℃), and keep the reaction at this temperature for 3-5 h (more preferably 3.5-4.5 h, most preferably 4 h) to carry out the cyclization reaction to generate unmodified benzoxazinone; Alkylation modification: Cool to 55-65℃ (more preferably 58-62℃, most preferably 60℃), add bromoethane (molar ratio of bromoethane to unmodified benzoxazinone 1.0-1.2:1, more preferably 1.05-1.15:1, most preferably 1.1:1) and anhydrous potassium carbonate (catalyst), and maintain the temperature for 2.5-3.5h (more preferably 2.8-3.2h, most preferably 3h) to achieve ethoxylation modification of the hydroxyl group on the benzene ring; Post-processing: After the reaction is complete, cool to room temperature, filter to remove solid impurities, and distill the filtrate under reduced pressure (temperature 110-130℃, more preferably 115-125℃, most preferably 120℃; vacuum degree -0.090~-0.098MPa, more preferably -0.093~-0.097MPa, most preferably -0.095MPa) to remove the solvent and obtain the crude product; Purification: The crude product is recrystallized with n-hexane 1-3 times (more preferably 2 times), with the solid-liquid ratio of n-hexane to crude product being 1:6-1:10 (g / mL, more preferably 1:7-1:9, most preferably 1:8). After filtration, it is dried under vacuum at 75-85℃ (more preferably 78-82℃, most preferably 80℃) for 5-7 h (more preferably 5.5-6.5 h, most preferably 6 h) to obtain the white crystalline target product (alkyl-modified benzoxazinone).

[0016] Preferably, the auxiliary UV absorber is a phosphite compound; The phosphite compounds are one or more of the following: tris(2,4-di-tert-butylphenyl) phosphite (CAS31570-04-4), bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite (CAS26741-53-7), tris(nonylphenyl) phosphite (CAS26523-78-4), and tris(2-tert-butyl-4-methylphenyl) phosphite; More preferably, it is tris(2,4-di-tert-butylphenyl) phosphite or bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite, and most preferably tris(2,4-di-tert-butylphenyl) phosphite; The purity of the auxiliary UV absorber is selected to be ≥97%, more preferably ≥98%, and most preferably ≥99%; the acid value is selected to be ≤0.1mgKOH / g, more preferably ≤0.08mgKOH / g, and most preferably ≤0.05mgKOH / g. Preferably, the composite antioxidant is composed of a primary antioxidant and a secondary antioxidant, wherein the primary antioxidant is selected from hindered phenolic resins, including one or more of 2,4-dimethyl-6-tert-butylphenol formaldehyde resin (CAS27676-62-6, trade name TopanolCA modified), 4,4'-methylenebis(2,6-di-tert-butylphenol) formaldehyde resin, and 2-tert-butyl-4-methylphenol formaldehyde resin; More preferably, it is 2,4-dimethyl-6-tert-butylphenol formaldehyde resin, and most preferably, it is 2,4-dimethyl-6-tert-butylphenol formaldehyde resin with a hydroxyl value ≥350mgKOH / g; the softening point of the main antioxidant is selected to be ≥85℃, more preferably ≥90℃, and most preferably ≥95℃; the thermal decomposition temperature is selected to be ≥290℃, more preferably ≥300℃, and most preferably ≥310℃.

[0017] The co-antioxidant is selected from thiophosphate compounds, including one or more of the following: bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite (CAS26741-53-7), tetra(2,4-di-tert-butylphenyl) 4,4'-biphenyl diphosphite (CAS38613-77-3), tris(2,4-di-tert-butylphenyl) phosphite, and bis(octadecyl) pentaerythritol diphosphite; More preferably, it is bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, and most preferably, it is bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite with a phosphorus content ≥8.5%; the acid value of the auxiliary antioxidant is selected to be ≤0.1mgKOH / g, more preferably ≤0.08mgKOH / g, and most preferably ≤0.05mgKOH / g; the solubility in the plasticizer at 25°C is selected to be ≥8g / 100g, more preferably ≥10g / 100g, and most preferably ≥12g / 100g.

[0018] The weight ratio of the primary antioxidant to the secondary antioxidant is selected as (1-3):1, more preferably (1.5-2.5):1, and most preferably 2:1.

[0019] Preferably, the light stabilizer is a compound system of NOR-HALS type light stabilizer and sterically hindered amino ether type light stabilizer; The NOR-HALS type light stabilizer includes one or more of Tinuvin 123, Tinuvin 152, and Songlight 2920, more preferably Tinuvin 123 or Songlight 2920, and most preferably Tinuvin 123; The sterically hindered amino ether type light stabilizer includes one or more of UVINUL4050H, UVINUL5050H, and ADKStabLA-57, more preferably UVINUL4050H or ADKStabLA-57, and most preferably UVINUL4050H.

[0020] The weight ratio of NOR-HALS type light stabilizer to sterically hindered amino ether type light stabilizer is selected as 1:2-2:1, more preferably 1:1.5-1.5:1, and most preferably 1:1; The thermal decomposition temperature of the light stabilizer is selected to be ≥250℃, more preferably ≥270℃, and most preferably ≥290℃.

[0021] Preferably, the metal ion additive is selected from one or more of alkaline earth metal ions, zinc ions, and aluminum ions; More preferably, it is one or more of magnesium ions, calcium ions, and aluminum ions, and most preferably, it is a combination of magnesium ions and aluminum ions. The source of the metal ions is selected from organic acid salts or inorganic acid salts. The organic acid salts can be selected from one or more of acetate, formate, propionate, benzoate, and 2-ethylhexanoate. The inorganic acid salts can be selected from one or more of hydrochloride, nitrate, sulfate, and phosphate. More preferably, organic acid salts are selected, and most preferably, acetate (such as magnesium acetate, aluminum acetate, calcium acetate, and zinc acetate).

[0022] If magnesium ions are selected, their content is 20-50 ppm, more preferably 25-45 ppm, and most preferably 30-40 ppm; if aluminum ions are selected, their content is 5-15 ppm, more preferably 8-12 ppm, and most preferably 10 ppm; if calcium ions are selected, their content is 15-40 ppm, more preferably 20-35 ppm, and most preferably 25-30 ppm; if zinc ions are selected, their content is 10-30 ppm, more preferably 15-25 ppm, and most preferably 20 ppm.

[0023] This invention also provides a method for preparing the above-mentioned highly efficient selective UV absorber film based on polyvinyl acetal, comprising the following steps: S1. Weigh the raw materials according to the stated mass fractions; S2. Mix the raw materials evenly, melt and extrude, stretch, shape and trim the edges, and roll up to obtain a high-efficiency selective UV absorber film.

[0024] The mixing temperature is 90-110℃ (more preferably 95-105℃, most preferably 100℃), the mixing time is 25-35 min, and the rotation speed is 1200-1800 r / min (more preferably 1400-1600 r / min, most preferably 1500 r / min). The melt extrusion process uses a twin-screw extruder with an extrusion temperature of 150-200℃, a screw speed of 250-350 r / min, and a die temperature of 160-190℃. The stretching and setting process involves biaxially stretching the extruded film at 75-105°C (more preferably 80-100°C, most preferably 85-95°C), with a longitudinal stretching ratio of 1.1-1.6 times (more preferably 1.2-1.5 times, most preferably 1.3-1.4 times) and a transverse stretching ratio of 1.2-1.7 times (more preferably 1.3-1.6 times, most preferably 1.4-1.5 times), followed by heat setting at 110-130°C (more preferably 115-125°C, most preferably 120°C) for 4-6 minutes (more preferably 4.5-5.5 minutes, most preferably 5 minutes). The finished film with a high-efficiency selective UV absorption film thickness of 0.38-1.5 mm (more preferably 0.5-1.2 mm, most preferably 0.76-1.0 mm) has a winding tension controlled at 50-150 N (more preferably 80-120 N, most preferably 100 N).

[0025] It contains at least the following beneficial technical effects: (1) The UV absorber is innovative and has good compatibility: The present invention uses alkyl-modified benzoxazinone compounds prepared by itself as the core UV absorber. By introducing C4-C8 branched alkyl and C2-C4 alkoxy groups on the benzoxazinone matrix, the high-efficiency absorption performance of the benzoxazinone matrix for the UV-B band is retained, and the compatibility with polyvinyl alcohol acetal matrix and plasticizer is significantly improved by alkyl chain modification. The long-term use can reduce the precipitation rate to below 0.05%, which overcomes the defects of poor compatibility and easy precipitation of existing benzoxazinone absorbers.

[0026] (2) Excellent optical selectivity: The transmittance of the membrane material of the present invention can reach more than 84% in the UV-A band and as low as 3.8% in the UV-B band, achieving efficient blocking of UV-B and high transmittance of UV-A, which can meet the specific needs of selective transmission / blocking of UV radiation for greenhouse coverings, optoelectronic modules, colorless window glass and bird protection window glass.

[0027] (3) Outstanding synergistic effect of antioxidant and UV absorption: The present invention uses a composite antioxidant system composed of hindered phenolic resin as the main antioxidant and thiophosphate as the auxiliary antioxidant, which forms a synergistic effect with alkyl-modified benzoxazinone UV absorbers. This system can effectively capture peroxides generated during heat processing and inhibit free radical degradation induced by UV radiation. The yellowing increment Δb* after long-term radiation can be controlled below 0.7, and the tensile strength retention rate after heat aging can reach more than 92%, which is significantly better than the traditional single phenolic antioxidant system.

[0028] (4) Excellent long-term stability and compatibility: This invention introduces a compound system of NOR-HALS type light stabilizer and sterically hindered amino ether type light stabilizer, combined with the stabilizing effect of alkaline earth metal ions, and strictly controls the content of alkali metal ions, effectively suppressing the performance degradation of the membrane material under high temperature and humidity, strong radiation and extreme temperature conditions. At the same time, the physicochemical parameters of each component have been carefully selected and optimized to ensure excellent compatibility with the matrix resin and plasticizer, with no risk of precipitation and good high-temperature stability.

[0029] (5) The preparation method is controllable and suitable for industrial production: The preparation method of alkyl-modified benzoxazinone UV absorbers provided by this invention has mild reaction conditions, clear steps, high product purity, and stable yield, making it suitable for industrial mass production. The membrane material is prepared by melt extrusion biaxial stretching process, which has a wide process window and allows for flexible adjustment of component ratios and process parameters according to different application scenarios, making it highly adaptable.

[0030] In summary, this invention provides a UV-absorbing film based on polyvinyl acetal that combines high UV-B blocking efficiency, high UV-A transmittance, low yellowing, high stability, and excellent compatibility. It can be widely used in fields such as optoelectronic module encapsulation, greenhouse coverings, glass laminates in the furniture industry, colorless window glass, and bird protection window glass. Detailed Implementation

[0031] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0032] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0033] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0034] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be obvious to those skilled in the art. This application specification and embodiments are merely exemplary.

[0035] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0036] Unless otherwise specified, "room temperature" and "normal temperature" in this invention refer to 25±2℃.

[0037] Unless otherwise specified, all raw materials or instruments used in the following embodiments of the present invention are commercially available.

[0038] Preparation of UV absorbers The alkyl-modified benzoxazinone was prepared according to the following steps: Condensation reaction: 100 g of 2-tert-butyl-4-isopentylphenol (0.42 mol) and 37.8 g of ethoxyamine (0.50 mol) were added to a 500 mL reaction vessel, followed by 500 mL of anhydrous ethanol. After stirring and dissolving, the mixture was heated to 50 °C, and 51.3 g of 37% formaldehyde aqueous solution (0.63 mol) was added dropwise over 1 hour. The mixture was then kept at this temperature for 2 hours. Closed-loop reaction: Add 0.5 mol / L hydrochloric acid solution to adjust pH to 3.5, heat to 80℃, and maintain the temperature for 4 hours; Alkylation modification: Cool to 60℃, add bromoethane (48.2g, 0.46mol) and anhydrous potassium carbonate (2.9g, 0.021mol), and keep the reaction at this temperature for 3h; Post-processing: Cool to room temperature, filter to remove impurities, and remove solvent by vacuum distillation at 120℃ and -0.095MPa to obtain 128g of crude product; Purification: Recrystallize twice with 1024 mL of n-hexane, filter, and dry under vacuum at 80 °C for 6 h to obtain 112 g of white crystals, with a yield of 85% and a purity of 98.8%.

[0039] Product characterization results: FT-IR spectrum: 3050 cm⁻¹ -1 Nearby (CH stretching vibration of benzene ring), 1630 cm -1 Nearby (oxazinone ring C=N stretching vibration), 1250cm -1 Nearby (COC stretching vibration), 2960cm -1 Nearby (alkyl CH stretching vibration); UV-Vis spectrum: The maximum absorption peak is located at 300-310nm (UV-B band).

[0040] Example 1 Weigh the following by weight percentage: 72.5 wt% polyvinyl butyral (degree of polymerization 2500, hydroxyl content 16 wt%), 27.0 wt% plasticizer (DINA:DINCH:3G8=2:1:1), 0.1 wt% self-prepared alkyl-modified benzoxazinone, 0.05 wt% auxiliary UV absorber tris(2,4-di-tert-butylphenyl) phosphite, 0.15 wt% composite antioxidant (2,4-dimethyl-6-tert-butylphenol formaldehyde resin: bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite=2:1), 0.1 wt% light stabilizer (Tinuvin123:UVINUL4050H=1:1), metal ion additives are magnesium acetate 30ppm + aluminum acetate 10ppm, and other additives glyceryl monostearate.

[0041] Mixing ingredients: Polyvinyl alcohol acetal, plasticizer, self-prepared alkyl-modified benzoxazinone UV absorber, composite antioxidant, light stabilizer and other additives are added to a high-speed mixer according to the formula. The mixing temperature is 100℃, the mixing time is 30min, and the speed is 1500r / min to obtain a homogeneous mixture. Melt extrusion: The mixture is added to a twin-screw extruder at an extrusion temperature of 175°C and a screw speed of 300 r / min. The mixture is then extruded through a T-die to form a film at a die temperature of 178°C. Stretching and setting: The extruded film is biaxially stretched at 90°C, with a longitudinal stretching ratio of 1.3 times and a transverse stretching ratio of 1.4 times, and then heat-set at 120°C for 5 minutes. Post-processing: edge trimming and winding to obtain a finished film with a thickness of 0.8 mm, with the winding tension controlled at 100 N.

[0042] Example 2 Weigh the following by weight percentage: 72.4 wt% polyvinyl butyral (degree of polymerization 2500, hydroxyl content 16 wt%), 27.0 wt% plasticizer (DINA:DINCH:3G8=2:1:1), 0.2 wt% self-prepared alkyl-modified benzoxazinone, 0.05 wt% auxiliary UV absorber tris(2,4-di-tert-butylphenyl) phosphite, 0.25 wt% composite antioxidant (2,4-dimethyl-6-tert-butylphenol formaldehyde resin: bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite=2:1), 0.1 wt% light stabilizer (Tinuvin123:UVINUL4050H=1:1), metal ion additives are magnesium acetate 30ppm + aluminum acetate 10ppm, and other additives glyceryl monostearate.

[0043] Mixing ingredients: Polyvinyl alcohol acetal, plasticizer, self-prepared alkyl-modified benzoxazinone UV absorber, composite antioxidant, light stabilizer and other additives are added to a high-speed mixer according to the formula. The mixing temperature is 90℃, the mixing time is 25min, and the speed is 1200r / min to obtain a homogeneous mixture. Melt extrusion: The mixture is added to a twin-screw extruder, the extrusion temperature is 150℃, the screw speed is 250r / min, and the film is extruded through a T-die at a die temperature of 160℃. Stretching and setting: The extruded film is biaxially stretched at 75°C, with a longitudinal stretching ratio of 1.1 times and a transverse stretching ratio of 1.2 times, and then heat-set at 110°C for 4 minutes; Post-processing: trimming and winding to obtain a finished film with a thickness of 0.38mm, with the winding tension controlled at 50N.

[0044] Example 3 Weigh the following by weight percentage: 72.3 wt% polyvinyl butyral (degree of polymerization 2500, hydroxyl content 16 wt%), 27.0 wt% plasticizer (DINA:DINCH:3G8=2:1:1), 0.3 wt% self-prepared alkyl-modified benzoxazinone, 0.05 wt% auxiliary UV absorber tris(2,4-di-tert-butylphenyl) phosphite, 0.35 wt% composite antioxidant (2,4-dimethyl-6-tert-butylphenol formaldehyde resin: bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite=2:1), 0.1 wt% light stabilizer (Tinuvin123:UVINUL4050H=1:1), metal ion additives are magnesium acetate 30 ppm + aluminum acetate 10 ppm, and other additives glyceryl monostearate.

[0045] Mixing ingredients: Polyvinyl alcohol acetal, plasticizer, self-prepared alkyl-modified benzoxazinone UV absorber, composite antioxidant, light stabilizer and other additives are added to a high-speed mixer according to the formula. The mixing temperature is 110℃, the mixing time is 35min, and the speed is 1800r / min to obtain a homogeneous mixture. Melt extrusion: The mixture is added to a twin-screw extruder at an extrusion temperature of 200°C and a screw speed of 350 r / min. The mixture is then extruded through a T-die to form a film at a die temperature of 190°C. Stretching and setting: The extruded film is biaxially stretched at 105°C, with a longitudinal stretching ratio of 1.6 times and a transverse stretching ratio of 1.7 times, and then heat-set at 130°C for 6 minutes. Post-processing: trimming and winding to obtain a finished film with a thickness of 1.5mm, with the winding tension controlled at 150N.

[0046] Comparative Example 1: Weigh the following by weight percentage: 72.3 wt% polyvinyl butyral (degree of polymerization 2500, hydroxyl content 16 wt%), 27.0 wt% plasticizer (DINA:DINCH:3G8=2:1:1), 0.15 wt% unmodified benzoxazinone (CAS19622-10-9), no auxiliary UV absorber, 0.15 wt% antioxidant Irganox1076, 0.1 wt% light stabilizer (Tinuvin123:UVINUL4050H=1:1), 50 ppm magnesium acetate as a single metal ion additive, and 0.05 wt% other additives glyceryl monostearate.

[0047] The preparation method is the same as in Example 1.

[0048] Comparative Example 2: Weigh the following by weight percentage: 72.4 wt% polyvinyl butyral (degree of polymerization 2500, hydroxyl content 16 wt%), 27.0 wt% plasticizer (DINA:DINCH:3G8=2:1:1), 0.15 wt% Tinuvin 312 (oxaloyl aniline type), no auxiliary UV absorber, 0.15 wt% antioxidant Lowinox 44B25, 0.1 wt% light stabilizer (Tinuvin 123:UVINUL 4050H=1:1), magnesium acetate 40 ppm metal ion additive, and 0.05 wt% other additives glyceryl monostearate.

[0049] The preparation method is the same as in Example 1.

[0050] Comparative Example 3: Weigh the following by weight percentage: 72.5 wt% polyvinyl butyral (degree of polymerization 2500, hydroxyl content 16 wt%), 27.0 wt% plasticizer (DINA:DINCH:3G8=2:1:1), no core UV absorber, no auxiliary UV absorber, 0.15 wt% single antioxidant BHT, 0.1 wt% light stabilizer (Tinuvin123:UVINUL4050H=1:1), no metal ion additives, and 0.05 wt% other additives glyceryl monostearate.

[0051] The preparation method is the same as in Example 1.

[0052] Comparative Example 4: Weigh the following by weight percentage: 72.3 wt% polyvinyl butyral (degree of polymerization 2500, hydroxyl content 16 wt%), 27.0 wt% plasticizer (DINA:DINCH:3G8=2:1:1), 0.2 wt% self-prepared alkyl-modified benzoxazinone, without auxiliary UV absorber, 0.2 wt% antioxidant Irganox1010, 0.1 wt% light stabilizer (Tinuvin123:UVINUL4050H=1:1), metal ion additives are magnesium acetate 30ppm + sodium ions 20ppm, and other additives glyceryl monostearate.

[0053] The preparation method is the same as in Example 1.

[0054] Experimental Example 1 The tests for ultraviolet transmittance, visible light transmittance, and direct solar transmittance shall be conducted in accordance with GB / T 2680-2021 and GB / T 32020-2015; the tests for yellowness value and yellowness increment shall be conducted in accordance with GB / T 2409-2008 and GB / T 16422.3-2014; the tests for tensile strength and thermal aging performance shall be conducted in accordance with GB / T 1040.3-2006 and GB / T 7141-2008; the tests for low-temperature impact strength shall be conducted in accordance with GB / T 1843-2008; the tests for volume resistivity shall be conducted in accordance with GB / T 1410-2006; and the tests for precipitation performance and high-temperature stability shall be conducted in accordance with GB / T 32020-2015.

[0055] The performance test results are shown in Table 1.

[0056] Table 1 Results Analysis Examples 1-3: With increasing dosage of the self-prepared alkyl-modified benzoxazinone, UV-B transmittance continuously decreased (3.8%-17.8%), while UV-A transmittance remained high (≥84%). The long-term yellowing increment Δb* ≤0.7, the precipitation rate ≤0.05%, the tensile strength retention rate after heat aging ≥92%, and the low-temperature impact strength ≥10.5kJ / m 2 Its overall performance is significantly better than that of each pair, and all core performance indicators meet the test standard requirements, demonstrating the synergistic advantages of UV absorbers and composite antioxidant systems.

[0057] Comparative Example 1: Unmodified benzoxazinone had poor compatibility (0.32% precipitation rate). When combined with the traditional antioxidant Irganox1076 and a single metal ion, the yellowing increase (1.5%) and thermal stability (78.5%) were significantly lower than those of the present invention, verifying the key role of alkyl modification in improving compatibility.

[0058] Comparative Examples 2-4: Traditional UV absorbers (oxaloyl aniline type) or antioxidant systems (single phenols, traditional hindered phenols) cannot simultaneously achieve optical selectivity, anti-yellowing and thermal stability, and have not optimized the types of metal ions and the content of alkali metal ions, resulting in significant performance degradation after long-term use and insufficient low-temperature impact strength, further highlighting the innovation of the component selection and synergistic design of this invention.

[0059] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A highly efficient selective UV absorber based on polyvinyl acetal, characterized in that, The components include the following parts by weight: The composition includes 55-95 parts of matrix resin, 5-45 parts of plasticizer, 0.005-1.2 parts of core UV absorber, 0.01-0.3 parts of auxiliary UV absorber, 0.01-0.8 parts of composite antioxidant, 0.01-0.8 parts of light stabilizer, and 0.0025-0.0065 parts of metal ion additive.

2. The high-efficiency selective UV absorption membrane based on polyvinyl acetal according to claim 1, characterized in that, The raw materials also include 0.002-0.1 parts of antistatic agent and 0.003-0.1 parts of adhesive modifier.

3. The high-efficiency selective UV absorption membrane based on polyvinyl acetal according to claim 1, characterized in that, The matrix resin includes one or more of polyvinyl butyral, polyvinyl formal, polyvinyl propionate, and polyvinyl pentaldehyde.

4. The high-efficiency selective UV absorption membrane based on polyvinyl acetal according to claim 1, characterized in that, The plasticizer includes one or more of the following: diisononyl adipate, diisononyl 1,2-cyclohexanedicarboxylate, triethylene glycol bis-2-ethylhexanoate, di-2-ethylhexyl sebacate, di-2-ethylhexyl adipate, dihexyl adipate, dibutyl sebacate, triethylene glycol bis-2-propylhexanoate, and di-2-butoxyethyl sebacate.

5. The high-efficiency selective UV absorption membrane based on polyvinyl acetal according to claim 1, characterized in that, The core UV absorber is an alkyl-modified benzoxazinone compound; The structural formula of the alkyl-modified benzoxazinone compound is: ； In the formula, R1 is selected from C4-C8 branched alkyl groups; R2 is selected from C2-C4 alkoxy groups.

6. The high-efficiency selective UV absorption membrane based on polyvinyl acetal according to claim 1, characterized in that, The auxiliary UV absorber is a phosphite compound; The phosphite compounds are one or more of the following: tris(2,4-di-tert-butylphenyl) phosphite (CAS31570-04-4), bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite (CAS26741-53-7), tris(nonylphenyl) phosphite (CAS26523-78-4), and tris(2-tert-butyl-4-methylphenyl) phosphite.

7. The high-efficiency selective UV absorption membrane based on polyvinyl acetal according to claim 1, characterized in that, The composite antioxidant is composed of a primary antioxidant and a secondary antioxidant. The primary antioxidant is selected from hindered phenolic resins, including one or more of 2,4-dimethyl-6-tert-butylphenol formaldehyde resin, 4,4'-methylenebis(2,6-di-tert-butylphenol) formaldehyde resin, and 2-tert-butyl-4-methylphenol formaldehyde resin. The co-antioxidant is selected from thiophosphate compounds, including one or more of bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite, tetra(2,4-di-tert-butylphenyl) 4,4'-biphenyl diphosphite, tris(2,4-di-tert-butylphenyl) phosphite, and bis(octadecyl) pentaerythritol diphosphite. The weight ratio of the primary antioxidant to the secondary antioxidant should be selected as 1:1 to 3:

1.

8. The high-efficiency selective UV absorption membrane based on polyvinyl acetal according to claim 1, characterized in that, The light stabilizer is a compound system of NOR-HALS type light stabilizer and sterically hindered amino ether type light stabilizer; The NOR-HALS type light stabilizer includes one or more of Tinuvin 123, Tinuvin 152, and Songlight 2920, more preferably Tinuvin 123 or Songlight 2920, and most preferably Tinuvin 123; The sterically hindered amino ether type light stabilizer includes one or more of UVINUL4050H, UVINUL5050H, and ADKStabLA-57, more preferably UVINUL4050H or ADKStabLA-57, and most preferably UVINUL4050H. The weight ratio of NOR-HALS type light stabilizer to sterically hindered amino ether type light stabilizer should be selected as 1:2-2:

1.

9. The high-efficiency selective UV absorption membrane based on polyvinyl acetal according to claim 1, characterized in that, The metal ion additive is selected from one or more of alkaline earth metal ions, zinc ions, and aluminum ions.

10. The method for preparing a highly efficient selective UV absorber film based on polyvinyl acetal according to any one of claims 1-9, characterized in that, Includes the following steps: S1. Weigh the raw materials according to the stated mass fractions; S2. Mix the raw materials evenly, melt and extrude, stretch, shape and trim the edges, and roll up to obtain a high-efficiency selective UV absorption film.

Images