High-performance polypropylene polarizing material, preparation method and application thereof

Abstract

The application discloses a kind of high-performance polypropylene material, polarizing material and its preparation method and application, belong to high polymer material technical field.The high-performance polypropylene material provided by the application includes: PP matrix resin 70-90 parts, cyclic olefin copolymer 5-15 parts, reactive monomer 0.5-2 parts, terminal hydroxyl hyperbranched polyester 0.5-2.0 parts, crown ether modified nano zinc oxide 1-5 parts, ionomer precursor 0.1-0.5 parts, initiator 0.05-0.2 parts, transparent nucleating agent 0.1-0.3 parts and antioxidant 0.2-0.5 parts by weight.The high-performance polypropylene material provided by the application has high transparency, low haze, high interfacial bonding strength, thermal stability and excellent dimensional stability, is suitable for polarizing sheet protective film field, and has good prospect.

Description

Technical Field

[0001] This invention relates to the field of polymer film materials technology, and more specifically, to a high-performance polypropylene material, a polarizing material, a preparation method thereof, and its application. Background Technology

[0002] Polypropylene (PP) film is considered an ideal candidate to replace cellulose triacetate (TAC) film in polarizer protective films due to its excellent moisture resistance and low cost. However, as a non-polar material, PP has problems such as difficult interfacial bonding, insufficient heat resistance, and difficulty in balancing transparency and rigidity, which limits its application in high-end polarizer protective films. Summary of the Invention

[0003] This invention aims to address the aforementioned problems in the prior art, providing a high-performance polypropylene, polarizing material, its preparation method, and its applications. This invention grafts functional substances onto PP material as the main component of a protective film, chemically grafting crown ether compounds onto the surface of nano-zinc oxide to prepare crown ether-modified nano-zinc oxide as a filler, achieving synergistic regulation of the multi-component system. Furthermore, by optimizing other components, the overall performance of the film is significantly improved.

[0004] In a first aspect, a high-performance polypropylene material is provided, comprising the following components in a total of 100 parts by weight: 70-90 parts of PP matrix resin; 5-15 parts of cyclic olefin copolymer; 0.5-2 parts of reactive monomers, including methacrylic acid or acrylic acid; 0.5-2.0 parts of hydroxyl-terminated hyperbranched polyester; Crown ether modified nano zinc oxide 1-5 parts; 0.1-0.5 parts of ionomer precursor; selected from at least one of zinc stearate and calcium stearate; Initiator 0.05-0.2 parts; 0.1-0.3 parts of a transparent nucleating agent; selected from sorbitol-based nucleating agents; Antioxidant, 0.2-0.5 parts.

[0005] Furthermore, the crown ether compounds do not contain benzene rings, because benzene rings are electron-withdrawing groups, which reduce the electron cloud density of the ether oxygen atom, thereby weakening the complexation ability of the crown ether with metal ions. Crown ethers without benzene rings have a high electron cloud density of the ether oxygen atom and a stronger complexation ability.

[0006] Preferably, the crown ether is selected from 2-hydroxymethyl-12-crown ether-4 and 2-hydroxymethyl-18-crown-6.

[0007] Furthermore, in the crown ether modified nano zinc oxide, crown ether compounds are grafted onto the surface of nano zinc oxide using epichlorohydrin as a bridging molecule.

[0008] Furthermore, the crown ether modified nano zinc oxide has a particle size of 20-80 nm and a crown ether grafting amount of 0.5-5.0 wt%. The loading amount of crown ether grafted polysulfone can be determined by thermogravimetric analysis (TGA), which can measure the change in grafting amount.

[0009] Within this range, the metal ions in the aforementioned ionomer precursor can form effective complexes with the crown ether holes on the surface of crown ether-modified nano zinc oxide, thereby achieving regulation of the ion cluster distribution.

[0010] Furthermore, the terminal hydroxyl hyperbranched polyester has an acid value of less than 5 mg KOH / g, a hydroxyl value of 370 mg KOH / g, a hydroxyl number of 5-7, a molecular weight of 920, and is manufactured by HyPer H301 from Wuhan Hyperbranched Resin Technology Co., Ltd.

[0011] Secondly, a method for preparing a high-performance polypropylene material is provided, comprising the following steps: (1) Premixing step: PP matrix resin, cyclic olefin copolymer, hydroxyl-terminated hyperbranched polyester, crown ether modified nano zinc oxide, transparent nucleating agent and antioxidant are dry mixed to obtain a solid mixture; (2) Reactive monomer preparation steps: Mix the reactive monomer, initiator and a small amount of PP matrix resin in a low-speed mixer to obtain a premix; (3) Reaction extrusion step: The solid mixture of step (1) is fed into the twin-screw extruder through the main feed port, the grafted masterbatch of step (2) is fed into the side feed port, and the ionomer precursor is fed into the rear side feed port at the same time. The mixture is melt-blended and grafted, extruded and granulated to obtain modified polypropylene granules. (4) Film forming step: The modified polypropylene granules from step (3) are made into a film by casting or biaxial stretching process.

[0012] Furthermore, the temperature settings of the twin-screw extruder in step (3) are as follows: feeding section 160-170℃, melting section 180-190℃, reaction section 190-200℃, die head 180-185℃; screw speed 150-300 rpm; residence time 1-3 minutes.

[0013] Furthermore, during the reaction extrusion process described in step (3), a vacuum devolatilization device is activated to remove unreacted monomers and byproducts.

[0014] Furthermore, the preparation method of the crown ether modified nano zinc oxide includes the following steps: Nano-zinc oxide was vacuum dried at 100-120℃ for 2-4 hours to remove adsorbed moisture from its surface. Epichlorohydrin was dissolved in toluene, and the activated nano-zinc oxide was added. The mixture was reacted under alkaline conditions for 2-4 hours to allow the epichlorohydrin to open its ring and react with the hydroxyl groups on the surface of the nano-zinc oxide, thus obtaining epichlorohydrin-modified nano-zinc oxide. Crown ether compounds were dissolved in an anhydrous solvent, and the epichlorohydrin-modified nano-zinc oxide was added. The mixture was reacted at 60-80℃ for 6-12 hours in the presence of a catalyst to allow the active groups on the crown ether to react with the other end of the epichlorohydrin to form a covalent bond. After the reaction, the product was separated by centrifugation, and unreacted crown ethers and catalysts were repeatedly washed with solvent. The product was then vacuum dried at 60-80℃ to obtain crown ether-modified nano-zinc oxide.

[0015] Epichlorohydrin was used as a bridging molecule to firmly graft crown ethers onto the surface of nano-zinc oxide through chemical bonds, avoiding the migration and aggregation of nanofillers in traditional physical blending and ensuring the long-term effectiveness of the complexation sites. Then, in the reactive extrusion step, a separate feeding method was adopted: the reactive monomer and initiator were added as a premix from the side feed port, effectively preventing premature initiation that would lead to a decrease in grafting rate; the ionomer precursor was added from the rear section, preventing it from reacting prematurely with the reactive monomer in the melting section to form large-sized ionomer gels.

[0016] Furthermore, the alkaline conditions are achieved by adding triethylamine or sodium hydroxide, with the pH controlled at 8-10.

[0017] Furthermore, the catalyst is p-toluenesulfonic acid, and the amount used is 1-5% of the crown ether mass.

[0018] Furthermore, the amount of epichlorohydrin added is 20-30% of the mass of zinc oxide; the amount of crown ether added is 5-10% of the mass of zinc oxide.

[0019] Furthermore, the zinc oxide is zinc oxide that has not undergone hydrophobic modification.

[0020] Thirdly, a surface protective film is provided, the surface protective film comprising the above-mentioned high-performance polypropylene material.

[0021] Fourthly, a polarizing material is provided, the polarizing material comprising a release protective film, an adhesive layer, a functional layer, and the aforementioned surface protective film.

[0022] Compared with existing technologies, the high-performance polypropylene materials, polarizing materials, their preparation methods, and applications provided by this invention have the following beneficial effects: 1. By introducing cyclic olefin copolymers to blend with PP matrix resin, the crystal size and optical anisotropy of polypropylene are reduced; at the same time, the addition of hydroxyl-terminated hyperbranched polyester improves the interfacial compatibility within the system and significantly reduces light scattering; crown ether-modified nano zinc oxide serves as a nucleation site, refining spherulites; the synergistic effect of these four factors results in a final film that maintains high rigidity while possessing excellent optical transparency and low haze.

[0023] 2. This invention constructs a synergistic system of ionomer precursor and crown ether modified nano-zinc oxide. During reactive extrusion, the metal ions released by the ionomer precursor preferentially undergo complexation reactions with the crown ether vacancies grafted onto the surface of nano-zinc oxide, precisely anchoring the originally randomly distributed ion clusters that lead to local stress concentration onto the nanoparticle surface. On the one hand, this avoids excessive free metal ions catalyzing the degradation of PP or forming large-sized agglomerates; on the other hand, through the action of crown ether, inorganic nanoparticles and polymer matrix are indirectly connected by ionic bonds, forming a uniform physical-chemical crosslinking network, which greatly improves the cohesive strength of the film and the interfacial bonding force with the polarizer functional layer.

[0024] 3. The crown ether-modified nano-zinc oxide used in this invention possesses excellent thermal stability. Its uniform dispersion acts as a physical cross-linking point, increasing the material's heat distortion temperature. Simultaneously, because the crown ether is chemically grafted onto the nanoparticle surface and the ionomer precursor is effectively complexed, no small molecule substances remain or precipitate in the system, preventing contamination of the functional layer during subsequent polarizer processing or use, thus ensuring the long-term stability of the polarizer. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below with reference to specific embodiments. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention. Example 1

[0026] I. Preparation of crown ether modified nano zinc oxide: (1) Place 100g of nano zinc oxide in a vacuum drying oven and dry it at 110℃ for 3 hours to remove the surface adsorbed moisture; (2) Add the dried nano zinc oxide to 500 ml toluene, sonicate for 30 minutes, add 25 g epichlorohydrin (25% of the mass of zinc oxide), and add triethylamine to adjust the pH to about 9. Under nitrogen protection, heat to 70 °C and reflux for 3 hours. After the reaction is completed, centrifuge and wash three times with anhydrous ethanol. Dry under vacuum at 60 °C to obtain epichlorohydrin modified nano zinc oxide. (3) Dissolve 8g of 2-hydroxymethyl-12-crown ether-4 (8% of the mass of zinc oxide) in 300ml of anhydrous ethanol, add the epichlorohydrin-modified nano zinc oxide obtained in the previous step, and add p-toluenesulfonic acid accounting for 3% of the mass of crown ether. Heat to 75℃ and react for 10 hours under nitrogen protection.

[0027] (4) After the reaction is completed, the product is separated by centrifugation. It is first washed three times with anhydrous ethanol, then washed twice with deionized water to remove unreacted crown ether, catalyst and by-products. Finally, it is vacuum dried at 70°C for 12 hours to obtain crown ether modified nano zinc oxide.

[0028] According to laser particle size analyzer, the average dispersed particle size of CM-ZnO-1 in the polymer matrix is ​​about 60 nm; according to thermogravimetric analysis (TGA), the grafting amount of crown ether is about 3.8 wt%.

[0029] II. Preparation of Polypropylene Materials: Step 1: Add 78 parts of PP matrix resin, 10 parts of cyclic olefin copolymer (Mitsui APL5014CL), 1 part of hydroxyl-terminated hyperbranched polyester (HyPer H301), 3 parts of crown ether modified nano zinc oxide, 0.2 parts of 1,3:2,4-di(3,4-dimethylbenzyl)-D-sorbitol (commercial Millad 3988), and 0.3 parts of antioxidant 168 (tris(2,4-di-tert-butylphenyl) phosphite) to a high-speed mixer and dry mix at room temperature for 5 minutes to obtain a solid mixture; Step 2: Add 2 parts of PP matrix resin, 1.2 parts of reactive monomer MAA and 0.1 parts of initiator DCP to a low-speed mixer and mix at room temperature for 10 minutes to obtain a premix. Step 3: Add the solid mixture from Step 1 through the main feed port of the twin-screw extruder. Add the premix from Step 2 through the first side feed port of the extruder (located before the melting section). Add the ionomer precursor zinc stearate through the second side feed port of the extruder (located in the reaction section). Control the temperature of the feeding section at 165°C, the melting section at 185°C, the reaction section at 195°C, and the die head at 182°C. The screw speed is 200 rpm. The material residence time is approximately 2 minutes. During the extrusion process, the vacuum devolatilization device is activated to remove unreacted monomers and low-molecular-weight byproducts. The material is extruded, stretched, cooled, and granulated to obtain modified polypropylene granules. Step 4: The modified polypropylene granules are processed into a film using a casting extruder. The temperature of the casting roller is controlled at 30°C. The film is then wound up to obtain a high-performance polypropylene film material with a thickness of approximately 60 μm. Example 2

[0030] The amounts of each substance added in this embodiment are as follows, and other characteristics are the same as in Example 1.

[0031] 85 parts of PP matrix resin; 7 parts of cyclic olefin copolymer; 2 parts of reactive monomer, including methacrylic acid or acrylic acid; 1.5 parts of hydroxyl-terminated hyperbranched polyester; 3 parts of crown ether modified nano zinc oxide; 0.5 parts of calcium stearate; 0.2 parts of initiator; 0.3 parts of transparent nucleating agent; nucleating agent selected from sorbitol; 0.5 parts of antioxidant. Example 3

[0032] The amount of ionomer precursor (zinc stearate) was adjusted to 0.15 parts, and the amount of crown ether modified nano zinc oxide was adjusted to 2.0 parts, so that the mass ratio was 1:13.3. All other characteristics were the same as in Example 1.

[0033] Comparative Example 1 Instead of adding crown ether modified nano zinc oxide, an equal amount (3.0 parts) of unmodified nano zinc oxide was added, and all other characteristics were the same as in Example 1.

[0034] Comparative Example 2 Without the addition of zinc stearate, all other characteristics are the same as in Example 1.

[0035] Comparative Example 3 In Example 1, 2-hydroxymethyl-12-crown ether-4 was replaced with 4'-aminobenzo-15-crown ether-5, and all other characteristics were the same as in Example 1.

[0036] Comparative Example 4 The hydroxyl-terminated hyperbranched polyester (HyPer H301) was replaced with a hyperbranched polyester (H997292, molecular weight: 600.67, hydroxyl value (mgKOH / g): 670-720, Maclean), and all other characteristics were the same as in Example 1.

[0037] Comparative Example 5 The cyclic olefin copolymer (Mitsui APL5014CL) was replaced with an ethylene octene copolymer (CAS: 26221-73-8), and all other characteristics were the same as in Example 1.

[0038] Comparative Example 6 Without the addition of a transparent nucleating agent, all other characteristics are the same as in Example 1. Performance testing

[0039] Table 1 Test methods and standards for examples and comparative examples Test Project Test standards / methods Test conditions / instructions Light transmittance & haze GB / T 2410-2008 Using a haze meter, the sample size is 50mm × 50mm. Tensile strength GB / T 1040.3-2006 Thin film sample, 15 mm wide, tensile speed 50 mm / min Elongation at break GB / T 1040.3-2006 Same as above Interface peeling force GB / T 2790-1995 After laminating the film with PVA film, a 180° peel test was performed. thermal shrinkage rate GB / T 12027-2004 Heat treatment at 120℃ for 30 minutes, then test longitudinal (MD) shrinkage rate. Water vapor transmission rate GB / T 1037-2021 38℃, 90% RH, weighing method Precipitation resistance Visual inspection / microscope The membrane was placed at 60℃ and 90% RH for 7 days, and the presence of any precipitates on the surface was observed. Table 2 Test Results of Examples and Comparative Examples Light transmittance (%) Haze (%) Tensile strength (MPa) Elongation at break (%) Interfacial peel force (N / 25mm) Heat shrinkage rate (%) Water vapor transmission rate (g / m²·24h) Precipitation resistance Example 1 91.8 0.7 59 210 4.3 1.1 2.1 No precipitation Example 2 91.2 0.9 57 195 4.0 1.2 2.3 No precipitation Example 3 90.5 1.2 51 170 3.1 1.6 2.8 No precipitation Comparative Example 1 87.8 2.8 46 140 2.0 2.3 3.9 Slight precipitation Comparative Example 2 89.5 1.8 44 155 1.7 2.1 3.5 No precipitation Comparative Example 3 90.1 1.6 50 165 2.8 1.9 3.1 No precipitation Comparative Example 4 88.5 2.2 47 145 2.2 2.2 3.7 Slight precipitation Comparative Example 5 89.2 2.0 48 280 2.4 2.5 4.5 Slight precipitation Comparative Example 6 90.0 1.5 54 185 3.8 1.8 2.6 No precipitation As can be seen from Table 2, the polypropylene material provided in this application has good transparency and mechanical properties, as well as good heat resistance, water resistance and stability. When it is combined with PVA film, it has strong interfacial bonding strength and good application prospects.

[0040] Compared to Example 1, Comparative Example 1 used unmodified nano-zinc oxide. Unmodified nano-zinc oxide has a surface rich in hydroxyl groups, exhibiting strong polarity and extremely poor compatibility with the non-polar PP matrix. During melt blending, the nanoparticles readily aggregate, forming micron-sized agglomerates. These agglomerates are larger than the visible light wavelength, causing strong light scattering, resulting in a significant decrease in transmittance and a sharp increase in haze. Furthermore, the agglomerated nanoparticles form stress concentration points in the matrix, easily inducing cracks under external forces, leading to a decrease in tensile strength. Simultaneously, due to the lack of crown ether complexation, the Zn released from the ionomer precursor (zinc stearate)... 2+ Unable to be effectively anchored, the nano-zinc oxide is randomly distributed in the matrix and cannot form a uniform cross-linked network, thus weakening the interfacial bonding. Unmodified nano-zinc oxide has strong surface adsorption capacity but weak bonding with the matrix, and easily migrates to the film surface under humid and hot conditions, causing slight precipitation.

[0041] Comparative Example 2, compared to Example 1, did not contain an ionomer precursor, and the system lacked releasable Zn. 2+ or Ca 2+ The crown ether vacancies on the surface of crown ether-modified nano-zinc oxide are in an "idle" state, unable to perform their function of anchoring ions and building cross-linked networks. Due to the lack of ionic cross-linking points, a physical-chemical cross-linked network cannot be formed. The strength of the material depends only on the entanglement force between PP molecular chains and a small amount of grafted MAA, resulting in poor tensile strength and interfacial peel strength. Furthermore, due to the lack of ionic cross-linking network constraints, the molecular chains are more prone to disorientation and slippage when heated, leading to increased thermal shrinkage.

[0042] Compared to Example 1, Comparative Example 3 uses a benzocrown ether. Since the benzene ring is an electron-withdrawing group, when the benzene ring is directly connected to the crown ether ring, it will cause the oxygen atom to react with the metal ion (Zn). 2+ / Ca 2+ The coordination ability of the ionomer precursor is weakened, and the metal ions released by the ionomer precursor cannot be fully captured by the crown ether. Some metal ions will still form tiny ion clusters in the matrix, and these clusters become new scattering centers and stress concentration points. Although the grafting reaction still occurs, its performance is better than Comparative Example 1, but significantly worse than Example 1, due to the low complexation efficiency.

[0043] Compared to Example 1, Comparative Example 4 uses a hydroxyl-terminated hyperbranched polyester with different parameters. The excessive polarity leads to a decrease in compatibility. During the mixing process, it may aggregate or induce the already dispersed nanoparticles to re-aggregate, resulting in increased haze.

[0044] A molecular weight that is too low results in insufficient reinforcing effect. A low molecular weight means the molecular chain is too short, which, while providing terminal hydroxyl groups, makes it difficult to form effective physical entanglement within the matrix. Therefore, its steric stabilizing effect on nanoparticles and its reinforcing effect on the matrix are significantly reduced.

[0045] Compared to Example 1, Comparative Example 5 uses ethylene-octene copolymer (POE) instead of cyclic olefin copolymer (COC). Specifically, it replaces the rigid cyclic COC with the flexible-chain POE elastomer. The cyclic structure of COC makes its molecular chains highly rigid, difficult to orient, and inherently lacks birefringence. POE, on the other hand, is a typical flexible-chain crystalline polymer, easily orienting and crystallizing during casting or stretching, forming larger crystalline regions that increase light scattering and haze. COC has a high glass transition temperature, significantly improving the heat resistance of the blend. POE, being an elastomer, has poor heat resistance. Replacing COC with POE reduces the rigidity of the matrix, increases the coefficient of thermal expansion, and worsens the thermal shrinkage rate. COC has extremely low water vapor permeability, while POE has flexible molecular chains, a large free volume, and significantly worse barrier properties than COC.

[0046] Compared to Example 1, Comparative Example 6 did not include a transparent nucleating agent (sorbitol-based transparent nucleating agent). Polypropylene itself crystallizes rapidly, and without a nucleating agent, the resulting spherulites are large. The interfaces of these large spherulites exhibit light scattering, leading to increased haze. Furthermore, the internal structure of large spherulites is loose, and the interfacial bonding between spherulites is weak. Adding a transparent nucleating agent refines the spherulite size, increases the interfacial area, and strengthens the bonding, which is beneficial for stress transfer and dispersion. In this invention, the transparent nucleating agent and crown ether-modified nano-zinc oxide jointly regulate the crystallization behavior. Removing this component weakens the crystallization regulation ability, resulting in a shift in optical and mechanical properties towards those of the comparative example.

Claims

1. A high-performance polypropylene material, characterized in that, Based on a total of 100 parts by weight, it includes the following components: 70-90 parts of PP matrix resin; 5-15 parts of cyclic olefin copolymer; 0.5-2 parts of reactive monomer; 0.5-2.0 parts of hydroxyl-terminated hyperbranched polyester; Crown ether modified nano zinc oxide 1-5 parts; 0.1-0.5 parts of ionomer precursor; Initiator 0.05-0.2 parts; 0.1-0.3 parts of transparent nucleating agent; Antioxidant 0.2-0.5 parts.

2. The high-performance polypropylene material according to claim 1, characterized in that, The transparent nucleating agent is selected from sorbitol-based nucleating agents; the reactive monomer includes methacrylic acid or acrylic acid; the ionomer precursor is selected from at least one of zinc stearate and calcium stearate.

3. The high-performance polypropylene material according to claim 1, characterized in that, The crown ether compound is a crown ether that does not contain a benzene ring; the crown ether is selected from 2-hydroxymethyl-12-crown ether-4 and 2-hydroxymethyl-18-crown-6.

4. The high-performance polypropylene material according to claim 1, characterized in that, The crown ether-modified nano-zinc oxide has a particle size of 20-80 nm and a crown ether grafting amount of 0.5-5.0 wt%. And / or the acid value (mg KOH / g) of the terminal hydroxyl hyperbranched polyester is less than 5, and the number of hydroxyl groups is 5-7.

5. A method for preparing a high-performance polypropylene material, characterized in that, Includes the following steps: (1) PP matrix resin, cyclic olefin copolymer, hydroxyl-terminated hyperbranched polyester, crown ether modified nano zinc oxide, transparent nucleating agent and antioxidant are dry mixed to obtain a solid mixture; (2) The reactive monomer, initiator and a small amount of PP matrix resin are mixed in a low-speed mixer to obtain a premix; (3) The solid mixture from step (1) is fed into the twin-screw extruder through the main feed port, the premix from step (2) is fed into the side feed port, and the ionomer precursor is fed into the rear side feed port. The mixture is then melt-blended and grafted, extruded and granulated to obtain modified polypropylene granules. (4) Film forming step: The modified polypropylene granules from step (3) are made into a film by casting or biaxial stretching process.

6. The method according to claim 5, characterized in that, The preparation method of the crown ether modified nano zinc oxide includes the following steps: Nano-zinc oxide was vacuum dried at 100-120℃ for 2-4 hours to remove adsorbed moisture from its surface. Epichlorohydrin was dissolved in toluene, and the activated nano-zinc oxide was added. The mixture was reacted under alkaline conditions for 2-4 hours to allow the epichlorohydrin to open its ring and react with the hydroxyl groups on the surface of the nano-zinc oxide, thus obtaining epichlorohydrin-modified nano-zinc oxide. Crown ether compounds were dissolved in an anhydrous solvent, and the epichlorohydrin-modified nano-zinc oxide was added. The mixture was reacted at 60-80℃ for 6-12 hours in the presence of a catalyst to allow the active groups on the crown ether to react with the other end of the epichlorohydrin to form a covalent bond. After the reaction, the product was separated by centrifugation, and unreacted crown ethers and catalysts were repeatedly washed with solvent. The product was then vacuum dried at 60-80℃ to obtain crown ether-modified nano-zinc oxide.

7. The method according to claim 6, characterized in that, The alkaline conditions are adjusted by adding triethylamine or sodium hydroxide solution, with the pH controlled at 8-10.

8. The method according to claim 6, characterized in that, The catalyst is p-toluenesulfonic acid, and the amount used is 1-5% of the crown ether mass; And / or the zinc oxide is zinc oxide that has not been hydrophobically modified.

9. A surface protective film, characterized in that, The surface protective film comprises the high-performance polypropylene material as described in any one of claims 1-4.

10. A polarizing material, characterized in that, The polarizing material includes a release protective film, an adhesive layer, a functional layer, and the surface protective film as described in claim 9.