A heat-resistant shrinkable PE isolation film base film and its preparation method

Abstract

The present invention discloses a heat-resistant shrinkable PE separator base film and a preparation method thereof, belonging to the technical field of separator films. Titanium dioxide is fixed in a hollow titanium-carbon sphere structure with a hollow interior, and then mica is modified, and dispersed nano-mica is uniformly coated on the surface of the modified titanium-carbon sphere. The core-shell microspheres are treated with γ-aminopropyltriethoxysilane, so that the core-shell microspheres are gradually loaded on the surface of the fiber to form a core-shell microsphere-fiber composite. When an external force acts on the PE separator film, the microspheres and the fiber serve as different stress-bearing units and can share the external force together. The presence of the microspheres can slow down the concentration of stress, while the fiber can guide the transmission of stress, and the titanium dioxide is fixed in the internal hollow cage structure, so that the anti-ultraviolet performance can be continuously exerted.

Description

Technical Field

[0001] The present invention belongs to the technical field of separator films, and particularly relates to a heat-resistant shrinkable PE separator film base film and a preparation method thereof. Background Art

[0002] Polyethylene (PE), as a fully saturated hydrocarbon skeleton, is one of the most important commercial polymers and is widely used as a key component for pipes, plates, containers, films, cables, coatings, fibers and other necessities. In the processes of producing the tread, sidewall, composite layer, and belt layer of radial tires, it is necessary to produce semi-finished rubber films. In order to avoid problems such as deformation and aging of the films, it is often necessary to laminate a separator film on the surface of the films. The separator film has a good oxygen barrier effect and can prevent the oxygen-sensitive film from aging. However, the tensile strength of the PE film is not good enough and it is easy to be stretched. When the separator film is peeled off from the surface of the film, the separator film is prone to problems such as tensile deformation and wrinkles, which easily affect the overall performance of the separator film, and it has poor light resistance in outdoor light environments and is prone to aging and yellowing.

[0003] Chinese Patent Publication No. CN116656029B discloses a PE separator and preservation film for radial tires and a preparation method thereof. By combining polyethylene, a compatibilizer, a polypropylene wax modified fiber material, and filler particles, and utilizing the compatibilizing effect of the compatibilizer, the bonding compatibility between polyethylene and the polypropylene wax modified fiber material and the filler particles is improved, facilitating the lamination of the separator and preservation film with the film; in combination with the advantage of the low viscosity of the polypropylene wax, it is convenient to tear the separator and preservation film from the surface of the film; and in combination with the relatively high strength of the fiber material and the filler particles in the polypropylene wax modified fiber material, the tensile strength of the separator and preservation film is improved.

[0004] The above solution involves the addition of various fillers, but only through the compatibilizing effect of the compatibilizer, it is not sufficient to enable the various fillers to achieve a good dispersion effect together, resulting in a lower toughness of the separator film and being prone to tearing during the stretching process. Summary of the Invention

[0005] The purpose of the present invention is to provide a heat-resistant shrinkable PE separator film base film and a preparation method thereof. By adding a core-shell microsphere-fiber composite as a filler to the PE separator film base film, the simple addition of various fillers is avoided, which affects their dispersibility, thereby improving the toughness and tear strength of the PE separator film base film.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] A preparation method of a heat-resistant shrinkable PE separator film base film is prepared by the following steps:

[0008] Step 1: Add modified titanium carbon spheres, dispersed nano mica powder, and a sodium dodecylbenzenesulfonate solution with a mass fraction of 15 - 20% into the reaction kettle according to the dosage ratio of 20 - 30 g : 3 - 4 g : 3 - 4 mL. Stir and mix at 50 - 65 °C and 400 - 500 r / min for 30 - 40 min. Transfer the mixture to a fluidized bed, and under the conditions of an air flow rate of 3000 - 3100 mL / min and a feeding rate of 0.5 - 0.6 g / min, mix with a jet mill for 15 - 20 min to obtain core - shell microsphere powder.

[0009] Step 2: Add the core - shell microsphere powder, γ - aminopropyltriethoxysilane, absolute ethanol, and deionized water into the reaction kettle. Stir at 80 - 85 °C and 400 - 500 r / min for 1 - 2 h, then add polyurethane fiber powder and continue to react for 1 - 2 h. Filter, wash the filter cake with deionized water 2 - 3 times, and dry in vacuum to obtain core - shell microsphere - fiber composite.

[0010] Step 3: Add the core - shell microsphere - fiber composite and high - density polyethylene into a twin - screw extruder according to the dosage ratio of 30 - 40 g : 500 - 600 g. Extrude and pelletize at 100 - 110 °C and a rotational speed of 50 - 60 r / min to obtain a heat - resistant shrinkable PE isolation film base film.

[0011] Furthermore, the dosage ratio of the core - shell microsphere powder, γ - aminopropyltriethoxysilane, absolute ethanol, deionized water, and polyurethane fiber powder is 50 - 60 g : 20 - 30 mL : 300 - 400 mL : 800 - 900 mL : 30 - 35 g.

[0012] Furthermore, the modified titanium carbon spheres in Step 1 are prepared through the following steps:

[0013] Add hollow titanium carbon sphere powder and a nitric acid solution with a concentration of 1 mol / L into the reaction kettle according to the dosage ratio of 20 - 25 g : 100 - 120 mL. Stir and pickling at 50 - 55 °C and 400 - 500 r / min for 1 - 1.2 h. Filter, wash the filter cake with deionized water until the last washing liquid is neutral, and vacuum dry at 60 - 80 °C for 1 - 2 h to obtain modified titanium carbon spheres.

[0014] Furthermore, the polyurethane fiber powder in Step 2 is prepared through the following steps:

[0015] Add polyurethane and dimethylformamide into the reaction kettle according to the dosage ratio of 50 - 60 g : 200 - 300 mL. Stir at 20 - 25 °C and 400 - 500 r / min for 30 - 40 min, carry out wet spinning using pure water as a coagulation bath, cure for 30 - 40 min, shear and crush to obtain polyurethane fiber powder with a length of 1 - 2 mm.

[0016] Further, the hollow titanium carbon sphere powder is prepared through the following steps:

[0017] Add chitosan, nickel acetate, and an acetic acid solution with a mass fraction of 1 - 2% into a reaction kettle, stir for 30 - 40 min under the conditions of 20 - 25°C and 400 - 500 r / min, then add γ - polyglutamic acid and deionized water, continue to stir for 1 - 2 h, add tetrabutyl titanate, stir for 2 - 3 h under the conditions of 50 - 65°C and 400 - 500 r / min, transfer the product to a muffle furnace, heat to 700 - 750°C under a nitrogen atmosphere, keep the temperature for 2 - 3 h, wash the product with a hydrochloric acid solution with a mass fraction of 30 - 40% and deionized water respectively for 2 - 3 times, and vacuum - dry at 60 - 80°C for 1 - 2 h to obtain the hollow titanium carbon sphere powder.

[0018] Further, the dosage ratio of chitosan, nickel acetate, acetic acid solution, γ - polyglutamic acid, deionized water, and tetrabutyl titanate is 20 - 30 g : 0.2 - 0.4 g : 200 - 300 mL : 15 - 20 g : 200 - 300 mL : 40 - 50 mL.

[0019] Further, the dispersed nano - mica powder in step one is prepared through the following steps:

[0020] Add the modified nano - mica powder, stearic acid, xylene, and n - butanol into a reaction kettle, stir for 1 - 2 h under the conditions of 20 - 25°C and 400 - 500 r / min, filter, wash the filter cake with deionized water for 2 - 3 times, and vacuum - dry at 60 - 80°C for 1 - 2 h to obtain the dispersed nano - mica powder.

[0021] Further, the dosage ratio of the modified nano - mica powder, stearic acid, xylene, and n - butanol is 15 - 20 g : 3 - 4 g : 80 - 90 mL : 100 - 120 mL.

[0022] Further, the modified nano - mica powder is prepared through the following steps:

[0023] Add the modified mica powder and an ethanol solution with a mass fraction of 50 - 60% into a reaction kettle, use an ultrasonic device to perform ultrasonic crushing treatment at a power of 400 W for 2 - 3 h, then let it stand for 48 - 50 h, filter, wash the filter cake with deionized water for 2 - 3 times, and freeze - dry for 12 - 14 h to obtain the modified nano - mica powder.

[0024] Further, the dosage ratio of the modified mica powder and the ethanol solution is 20 - 22 g : 200 - 300 mL.

[0025] Further, the modified mica powder is prepared through the following steps:

[0026] Add coarse mica powder, citric acid, and deionized water into a reaction kettle, stir for 3 - 4 h under the conditions of 80 - 85 °C and 400 - 500 r / min, perform suction filtration, wash the filter cake with deionized water until the last washing liquid is neutral, and dry it in vacuum at 60 - 80 °C for 10 - 12 h to obtain modified mica powder.

[0027] Furthermore, the dosage ratio of coarse mica powder, citric acid, and deionized water is 20 - 30 g : 40 - 50 g : 800 - 900 mL.

[0028] Advantages of the present invention:

[0029] 1. The heat-resistant shrinkable PE isolation film base film prepared by the present invention forms modified titanium carbide spheres by fixing titanium dioxide in the hollow titanium carbide sphere structure with a hollow interior; ultrasonically crush and modify mica with citric acid to obtain modified nano mica powder with interlayer peeling, then treat it with stearic acid to obtain dispersed nano mica, uniformly coat the dispersed nano mica on the surface of the modified titanium carbide spheres to obtain core-shell microsphere powder. After the core-shell microspheres are treated with γ-aminopropyltriethoxysilane, the core-shell microspheres are gradually loaded on the surface of the fibers to form a core-shell microsphere-fiber composite. Co-extrude the core-shell microsphere-fiber composite and high-density polyethylene through a twin-screw extruder to obtain the heat-resistant shrinkable PE isolation film base film, which has excellent tensile strength and toughness, a rough and closely fitting surface, and superior high-temperature resistance and ultraviolet light resistance.

[0030] 2. The modified titanium carbide spheres of the present invention are intertwined and wound together through the van der Waals force and hydrogen bond interaction of chitosan and γ-polyglutamic acid to form a hollow cage-like structure inside. The titanic acid generated after the hydrolysis of tetrabutyl titanate is impregnated under vacuum to fill the inside of the hollow cage-like structure, and hollow titanium carbide spheres are obtained after carbonization. Through this structure, titanium dioxide can be fixed in the isolation film. The hollow cage-like structure inside not only provides sufficient filling space for titanic acid but also ensures the stability of the titanium carbide spheres in the isolation film, thus ensuring the long-term stability of the isolation film performance. The immobilization of titanium dioxide enables its photocatalytic performance and anti-ultraviolet performance to be continuously exerted, extending the service life of the isolation film; the design of the hollow titanium carbide spheres also endows the isolation film with a certain self-cleaning ability. Under photocatalysis, titanium dioxide can decompose the pollutants attached to the surface of the isolation film, thereby keeping its surface clean and smooth. This self-cleaning ability not only helps to improve the aesthetics of the isolation film but also reduces the performance degradation and aging problems caused by the accumulation of pollutants; chitosan and γ-polyglutamic acid, as natural polymer materials, are biodegradable and can be decomposed by microorganisms in the natural environment without causing pollution to the environment, which conforms to the concepts of green chemistry and sustainable development.

[0031] 3. The core-shell microsphere-fiber composite of the present invention is formed by uniformly coating the surface of modified titanium carbide spheres with dispersed nano-mica to form a core-shell microsphere structure. Then, the carboxyl groups on the surface of the core-shell microspheres react with the amino groups of γ-aminopropyltriethoxysilane, grafting γ-aminopropyltriethoxysilane onto the surface of the core-shell microspheres. Under hydrolysis, γ-aminopropyltriethoxysilane generates silanol groups that react with the hydroxyl groups on the surface of the polyurethane fibers, gradually loading the core-shell microspheres onto the surface of the fibers to form a core-shell microsphere-fiber composite. When an external force acts on the PE separator membrane, the core-shell microspheres and fibers, as different stress-bearing units, can share the external force together. The presence of the microspheres can slow down the concentration of stress, while the fibers can guide the transmission of stress, preventing the membrane material from rupturing due to excessive local stress, which helps to improve the toughness of the PE separator membrane. When subjected to external forces such as impact or tension, the interaction between the microspheres and fibers can absorb more energy, enhancing the tear resistance and tensile strength of the membrane. The core-shell microsphere-fiber structure also significantly improves the thermal stability of the PE separator membrane. In a high-temperature environment, the modified titanium carbide spheres act as effective thermal barriers, hindering the rapid transfer of heat and slowing down the thermal expansion rate of the membrane material, thus preventing the membrane from deforming or thermally cracking due to high temperature. At the same time, the fibers have relatively good thermal conductivity and can quickly conduct heat along the fiber direction, complementing the heat insulation effect of the titanium carbide spheres to achieve uniform heat distribution and effective heat management. Detailed Embodiments

[0032] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0033] Example 1: A method for preparing a heat-resistant shrinkable PE separator membrane base film is prepared through the following steps:

[0034] S1: Add 20 g of coarse mica powder, 40 g of citric acid, and 800 mL of deionized water into a reaction kettle, stir for 3 h under the conditions of 80 °C and 400 r / min, perform suction filtration, wash the filter cake with deionized water until the last washing liquid is neutral, and dry it in vacuum at 60 °C for 10 h to obtain modified mica powder; Add 20 g of modified mica powder and 200 mL of ethanol solution with a mass fraction of 50% into the reaction kettle, perform ultrasonic fragmentation treatment at a power of 400 W using an ultrasonic device for 2 h, then let it stand for 48 h, filter, wash the filter cake with deionized water twice, and freeze-dry for 12 h to obtain modified nano mica powder; Add 15 g of modified nano mica powder, 3 g of stearic acid, 80 mL of xylene, and 100 mL of n-butanol into the reaction kettle, stir at 20 °C and 400 r / min for 1 h, filter, wash the filter cake with deionized water twice, and dry it in vacuum at 60 °C for 1 h to obtain dispersed nano mica powder.

[0035] With its nano-scale ultra-thin structure, the modified nano mica powder can be more uniformly dispersed in the polymer matrix after being modified with stearic acid. This characteristic significantly improves the overall performance of the composite material, endows it with excellent high-temperature resistance and chemical stability, and enables it to maintain excellent performance in high-temperature environments. When applied to PE isolation films, the modified nano mica powder not only makes it perform well in high-temperature application scenarios, but also endows the isolation film with high visible light transmittance and excellent ultraviolet shielding performance. This effectively avoids the aging problem of the isolation film caused by direct sunlight during long-term outdoor use, and significantly extends its service life.

[0036] S2: Add 20 g of chitosan, 0.2 g of nickel acetate, and 200 mL of glacial acetic acid solution with a mass fraction of 1% into a reaction kettle, stir at 20 °C and 400 r / min for 30 min, then add 15 g of γ-polyglutamic acid and 200 mL of deionized water, continue to stir for 1 h, then add 40 mL of tetrabutyl titanate, stir at 50 °C and 400 r / min for 2 h, transfer the product to a muffle furnace, heat it to 700 °C under a nitrogen atmosphere, keep the temperature for 2 h, wash the product twice with hydrochloric acid solution with a mass fraction of 30% and deionized water respectively, and dry it in vacuum at 60 °C for 1 h to obtain hollow titanium carbon sphere powder; Add 20 g of hollow titanium carbon sphere powder and 100 mL of nitric acid solution with a concentration of 1 mol / L into the reaction kettle, stir and pickle at 50 °C and 400 r / min for 1 h, filter, wash the filter cake with deionized water until the last washing liquid is neutral, and dry it in vacuum at 60 °C for 1 h to obtain modified titanium carbon spheres.

[0037] Chitosan and γ-polyglutamic acid are intertwined and wound together through van der Waals forces and hydrogen bond interactions to form an internal hollow cage structure. The titanic acid generated after the hydrolysis of tetrabutyl titanate is impregnated under vacuum to fill the inside of the hollow cage structure, and hollow titanium carbon spheres are obtained after carbonization.

[0038] The self-cleaning effect of nano-titanium dioxide is also based on its photocatalytic performance. Under ultraviolet irradiation, the free radicals generated on the surface of titanium dioxide can not only sterilize, but also decompose various organic and inorganic substances. When dirt adheres to the surface of the PE isolation film, the photocatalytic action of titanium dioxide can decompose it into harmless substances such as carbon dioxide, water and inorganic substances.

[0039] S3: Add 20 g of modified titanium-carbon spheres, 3 g of dispersed nano-mica powder and 3 mL of a 15% sodium dodecylbenzenesulfonate solution into the reaction kettle, stir and mix for 30 min at 50 °C and 400 r / min, transfer the mixture to the fluidized bed, and under the conditions of an air flow rate of 3000 mL / min and a feeding rate of 0.5 g / min, mix with a jet mill for 15 min to obtain core-shell microsphere powder.

[0040] Using a fluidized bed jet mill, the dispersed nano-mica powder is in a spread state and collides and mixes fluidized with the modified titanium-carbon spheres in the jet mill chamber. Due to the wetting effect of a trace amount of surfactant, the dispersed nano-mica can collide with the modified titanium-carbon spheres on the surface of the microspheres, and a core-shell microsphere with nano-mica as the shell and modified titanium-carbon spheres as the core is obtained.

[0041] S4: Add 50 g of polyurethane and 200 mL of dimethylformamide into the reaction kettle, stir for 30 min at 20 °C and 400 r / min, perform wet spinning using pure water as the coagulation bath, cure for 30 min, shear and crush to obtain polyurethane fiber powder with a length of 1-2 mm; Add 50 g of core-shell microsphere powder, 20 mL of γ-aminopropyltriethoxysilane, 300 mL of absolute ethanol and 800 mL of deionized water into the reaction kettle, stir for 1 h at 80 °C and 400 r / min, then add 30 g of polyurethane fiber powder and continue to react for 1 h, filter, wash the filter cake with deionized water twice, and dry in vacuum at 60 °C for 1 h to obtain a core-shell microsphere-fiber composite.

[0042] S5: Add 30 g of the core-shell microsphere-fiber composite and 500 g of high-density polyethylene into a twin-screw extruder, and extrude and pelletize at 100 °C and a rotation speed of 50 r / min to obtain a heat-resistant shrinkable PE isolation film base film.

[0043] The carboxyl groups on the surface of the core-shell microspheres combine with the amino groups of γ-aminopropyltriethoxysilane, enabling γ-aminopropyltriethoxysilane to graft onto the surface of the core-shell microspheres. Under the action of hydrolysis, γ-aminopropyltriethoxysilane generates silanol groups that react with the hydroxyl groups on the surface of the polyurethane fibers, thereby gradually loading the core-shell microspheres on the surface of the fibers to form a core-shell microsphere-fiber composite.

[0044] When an external force acts on the PE isolation film, the microspheres and fibers, as different stress-bearing units, can jointly share the external force. The presence of the microspheres can slow down the stress concentration, while the fibers can guide the stress transmission, avoiding the rupture of the film material caused by excessive local stress, which helps to improve the toughness of the PE isolation film. When subjected to external forces such as impact or tension, the interaction between the microspheres and fibers can absorb more energy, thereby enhancing the tear resistance and tensile resistance of the film.

[0045] Example 2: A preparation method of a heat-shrinkable PE isolation film base film is prepared by the following steps:

[0046] S1: Add 25 g of coarse mica powder, 45 g of citric acid, and 850 mL of deionized water into a reaction kettle, stir at 83 °C and 450 r / min for 3.4 h, filter by suction, wash the filter cake with deionized water until the last washing liquid is neutral, and vacuum dry at 70 °C for 11 h to obtain modified mica powder; add 21 g of modified mica powder and 250 mL of an ethanol solution with a mass fraction of 55% into the reaction kettle, perform ultrasonic crushing treatment at a power of 400 W for 2.3 h using an ultrasonic device, then let it stand for 49 h, filter, wash the filter cake with deionized water twice, and freeze-dry for 13 h to obtain modified nano mica powder; add 18 g of modified nano mica powder, 3.4 g of stearic acid, 85 mL of xylene, and 110 mL of n-butanol into the reaction kettle, stir at 23 °C and 450 r / min for 1.2 h, filter, wash the filter cake with deionized water twice, and vacuum dry at 70 °C for 1.2 h to obtain dispersed nano mica powder.

[0047] S2: Add 25 g of chitosan, 0.3 g of nickel acetate, and 250 mL of an acetic acid solution with a mass fraction of 1.5% into a reaction kettle, stir at 23 °C and 450 r / min for 35 min, then add 18 g of γ-polyglutamic acid and 250 mL of deionized water, continue to stir for 1.2 h, then add 45 mL of tetrabutyl titanate, stir at 58 °C and 450 r / min for 2.3 h, transfer the product to a muffle furnace, heat to 730 °C under a nitrogen atmosphere, keep the temperature for 2.3 h, wash the product twice with a hydrochloric acid solution with a mass fraction of 35% and deionized water respectively, and vacuum dry at 70 °C for 1.2 h to obtain hollow titanium carbon sphere powder; add 23 g of hollow titanium carbon sphere powder and 110 mL of a nitric acid solution with a concentration of 1 mol / L into the reaction kettle, stir and pickle at 53 °C and 450 r / min for 1.1 h, filter, wash the filter cake with deionized water until the last washing liquid is neutral, and vacuum dry at 70 °C for 1.2 h to obtain modified titanium carbon spheres.

[0048] S3: Add 25 g of modified titanium carbon spheres, 3.4 g of dispersed nano mica powder, and 3.5 mL of a sodium dodecylbenzenesulfonate solution with a mass fraction of 18% into a reaction kettle, stir and mix for 35 min under the conditions of 60 °C and 450 r / min, transfer the mixed solution to a fluidized bed air classifier for fine mixing, and mix for 18 min under the conditions of an air flow rate of 3050 mL / min and a feeding rate of 0.55 g / min to obtain core-shell microsphere powder.

[0049] S4: Add 60 g of polyurethane and 300 mL of dimethylformamide into a reaction kettle, stir for 40 min under the conditions of 25 °C and 500 r / min, perform wet spinning using pure water as a coagulation bath, cure for 40 min, shear and crush to obtain polyurethane fiber powder with a length of 1 - 2 mm; add 60 g of core-shell microsphere powder, 25 mL of γ-aminopropyltriethoxysilane, 350 mL of absolute ethanol, and 900 mL of deionized water into a reaction kettle, stir for 1.5 h under the conditions of 82 °C and 500 r / min, then add 32 g of polyurethane fiber powder, continue to react for 1.5 h, filter, wash the filter cake 3 times with deionized water, and vacuum dry at 80 °C for 2 h to obtain core-shell microsphere-fiber composite.

[0050] S5: Add 40 g of core-shell microsphere-fiber composite and 600 g of high-density polyethylene into a twin-screw extruder, extrude and pelletize at 105 °C and a rotation speed of 60 r / min to obtain a heat-resistant shrinkable PE isolation film base film.

[0051] Example 3: A preparation method of a heat-resistant shrinkable PE isolation film base film is prepared through the following steps:

[0052] S1: Add 30 g of coarse mica powder, 50 g of citric acid, and 900 mL of deionized water into a reaction kettle, stir for 4 h under the conditions of 85 °C and 500 r / min, perform suction filtration, wash the filter cake with deionized water until the last washing liquid is neutral, and vacuum dry at 80 °C for 12 h to obtain modified mica powder; add 22 g of modified mica powder and 300 mL of an ethanol solution with a mass fraction of 60% into a reaction kettle, perform ultrasonic crushing treatment at a power of 400 W using an ultrasonic device for 3 h, then let it stand for 50 h, filter, wash the filter cake 3 times with deionized water, and freeze-dry for 14 h to obtain modified nano mica powder; add 20 g of modified nano mica powder, 4 g of stearic acid, 90 mL of xylene, and 120 mL of n-butanol into a reaction kettle, stir for 2 h under the conditions of 25 °C and 500 r / min, filter, wash the filter cake 3 times with deionized water, and vacuum dry at 80 °C for 2 h to obtain dispersed nano mica powder.

[0053] S2: Add 30 g of chitosan, 0.4 g of nickel acetate, and 300 mL of glacial acetic acid solution with a mass fraction of 2% into a reaction kettle, stir for 40 min under the conditions of 25 °C and 500 r / min, then add 20 g of γ-polyglutamic acid and 300 mL of deionized water, continue to stir for 2 h, then add 50 mL of tetrabutyl titanate, stir for 3 h under the conditions of 65 °C and 500 r / min, transfer the product to a muffle furnace, heat to 750 °C under a nitrogen atmosphere, keep the temperature for 3 h, wash the product 3 times with a hydrochloric acid solution with a mass fraction of 40% and deionized water respectively, and dry it in vacuum at 80 °C for 2 h to obtain hollow titanium carbon sphere powder; Add 25 g of hollow titanium carbon sphere powder and 120 mL of nitric acid solution with a concentration of 1 mol / L into a reaction kettle, stir and pickle for 1.2 h under the conditions of 55 °C and 500 r / min, filter, wash the filter cake with deionized water until the last washing liquid is neutral, and dry it in vacuum at 80 °C for 2 h to obtain modified titanium carbon spheres.

[0054] S3: Add 30 g of modified titanium carbon spheres, 4 g of dispersed nano mica powder, and 4 mL of sodium dodecylbenzenesulfonate solution with a mass fraction of 20% into a reaction kettle, stir and mix for 40 min under the conditions of 65 °C and 500 r / min, transfer the mixture to a fluidized bed, and mix with a jet mill for 20 min under the conditions of an air flow rate of 3100 mL / min and a feeding rate of 0.6 g / min to obtain core-shell microsphere powder.

[0055] S4: Add 60 g of polyurethane and 300 mL of dimethylformamide into a reaction kettle, stir for 40 min under the conditions of 25 °C and 500 r / min, perform wet spinning using pure water as a coagulation bath, cure for 40 min, shear and crush to obtain polyurethane fiber powder with a length of 1 - 2 mm; Add 60 g of core-shell microsphere powder, 30 mL of γ-aminopropyltriethoxysilane, 400 mL of absolute ethanol, and 900 mL of deionized water into a reaction kettle, stir for 2 h under the conditions of 85 °C and 500 r / min, then add 35 g of polyurethane fiber powder, continue to react for 2 h, filter, wash the filter cake 3 times with deionized water, and dry it in vacuum at 80 °C for 2 h to obtain core-shell microsphere-fiber composite.

[0056] S5: Add 40 g of core-shell microsphere-fiber composite and 600 g of high-density polyethylene into a twin-screw extruder, extrude and pelletize at 110 °C and a rotation speed of 60 r / min to obtain a heat-resistant shrinkable PE isolation film base film.

[0057] Comparative Example 1: On the basis of Example 3, replace the dispersed nano mica powder in step S3 with the coarse mica powder in step S1, and keep the other steps unchanged to prepare a heat-resistant shrinkable PE isolation film base film.

[0058] Comparative Example 2: On the basis of Example 3, tetrabutyl titanate was omitted in step S2, and the remaining steps remained unchanged to prepare a heat-resistant shrinkable PE separator film base film.

[0059] Comparative Example 3: On the basis of Example 3, 30 g of coarse mica powder, 35 g of polyurethane fiber powder, and 30 g of modified titanium-carbon spheres were stirred and mixed evenly, and the remaining steps remained unchanged to prepare a heat-resistant shrinkable PE separator film base film.

[0060] The fluidized bed model is AB03.

[0061] Citric acid, chitosan, γ-polyglutamic acid, methyl methacrylate, benzoyl peroxide, and dimethylformamide were all purchased from Sigma-Aldrich.

[0062] The heat-resistant shrinkable PE separator film base films prepared in Examples 1 - 3 and Comparative Examples 1 - 3 were subjected to performance tests, and the results are shown in Table 1:

[0063] 1. Tensile strength detection: Refer to GB / T13022-1991 for the tensile test of plastic films to detect the tensile strength and record the data. The tensile strength is the ultimate tensile strength; the separator film base film was attached to the surface of the film, left standing for 2 h, then torn off, and then attached to the surface of the film again, left standing for 2 h, and torn off. The operation was repeated 20 times, and the tensile strength data was recorded again, which is the tensile strength.

[0064] 2. Wrinkle detection; after the heat-resistant shrinkable PE separator film base film was attached to the surface of the film, it was wound up, and then six wound-up films were stacked in a structure of 3, 2, 1 from bottom to top. Six films were taken as a group. After the six wound-up films were stacked and placed for 1 d, the separator film base film on the surface of the film was torn off, and the wrinkle area of the separator film base film on the surface of the middle film in the bottom row of the three films was observed, and the wrinkle area per unit area was recorded.

[0065] 3. Lamination effect detection; when the separator film base film was attached to the surface of the film, it was observed whether there was any air pocket problem on the surface of the film to evaluate the lamination effect, and the number of air pockets on a 1-square-meter film was recorded; no air pockets indicated good lamination effect.

[0066] 4. The heat resistance of the material was tested using a heat distortion Vicat softening point tester, with a heating rate of 100 °C / h.

[0067] 5. The tear strength of the separator film was determined by the pendulum method according to the standard of ASTM D1922-08.

[0068] 6. After each group of test samples was subjected to ultraviolet light aging treatment for 72 h, the performance test was continued.

[0069] Table 1 Performance test table of heat-resistant shrinkable PE separator film base film

[0070] As can be seen from Table 1, the tensile strength and heat distortion temperature of the heat-resistant shrinkable PE isolation film base films prepared in Examples 1-3 are significantly better than those of the comparative examples. After aging treatment, the degrees of decrease in strength and heat-resistant temperature are also less than those of the comparative examples, and the wrinkled area and the number of air pockets are significantly lower than those of the comparative examples. After aging treatment, the upward trends of the wrinkled area and the number of air pockets are significantly lower than those of the comparative examples, indicating that the heat-resistant shrinkable PE isolation film base films prepared by the present invention have excellent tensile strength and flexibility, the surface is rough and closely adherent, and the high-temperature resistance and ultraviolet light resistance are superior.

[0071] In Comparative Example 1, the dispersed nano mica powder was replaced with coarse mica powder. The modified nano mica powder has a nanoscale ultra-thin structure. After being modified with stearic acid, it can be more uniformly dispersed in the polymer matrix, thereby improving the overall performance of the composite material. After being replaced with coarse mica powder, there are electrostatic forces and van der Waals forces between the mica particles, making it easy for the mica particles to form aggregates when approaching each other, thus affecting the overall performance of the composite material.

[0072] In Comparative Example 2, tetrabutyl titanate was omitted, and titanium dioxide was fixed through an internally hollow cage structure. The cage structure not only provides sufficient filling space for titanium dioxide but also ensures the stability of the titanium-carbon spheres in the isolation film.

[0073] In Comparative Example 3, the coarse mica powder, polyurethane fiber powder, and modified titanium-carbon spheres were stirred and mixed evenly. Only by stirring and mixing, stable chemical bonds or strong interfacial interactions cannot be formed, resulting in interfacial defects between the coarse mica powder, polyurethane fiber powder, and titanium-carbon spheres, reducing the mechanical properties of the composite material. By forming core-shell microsphere-fiber composites, the interfacial damping can be effectively increased to jointly share external forces.

[0074] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device.

[0075] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a heat-shrinkable PE isolation film base film, characterized in that: Prepared by the following steps: Step 1: The hollow titanium carbon sphere powder is acid-washed to obtain modified titanium carbon spheres, and the modified nano mica powder is treated with stearic acid and ultrasonic crushing to obtain dispersed nano mica powder; the modified titanium carbon spheres, dispersed nano mica powder and 15-20wt% sodium dodecylbenzene sulfonate solution are added to the reactor in a dosage ratio of 20-30g: 3-4g: 3-4mL, and stirred for 30-40min. The mixture is transferred to a fluidized bed and mixed by air jet milling for 15-20min to obtain core-shell microsphere powder; Step 2: Add core-shell microsphere powder, γ-aminopropyltriethoxysilane, anhydrous ethanol and deionized water into a reaction kettle, stir for 1-2 hours, then add polyurethane fiber powder, continue to react for 1-2 hours, filter, wash, and vacuum dry to obtain a core-shell microsphere-fiber composite; Step 3: adding the core-shell microsphere-fiber composite and high-density polyethylene into a twin-screw extruder at a mass ratio of 30-40:500-600, extruding and granulating to obtain a heat-shrinkable PE isolation film base film; The hollow titanium carbon sphere powder is prepared by the following steps: Chitosan, nickel acetate and 1-2wt% glacial acetic acid solution are added into a reactor, stirred at 20-25°C and 400-500r / min for 30-40min, then γ-polyglutamic acid and deionized water are added, stirring is continued for 1-2h, and then tetrabutyl titanate is added, stirred at 50-65°C and 400-500r / min for 2-3h, the product is transferred into a muffle furnace, heated to 700-750°C under a nitrogen atmosphere, and kept warm for 2-3h, the product is washed 2-3 times with 30-40wt% hydrochloric acid solution and deionized water respectively, and vacuum dried to obtain hollow titanium carbon sphere powder.

2. The method for preparing a heat-shrinkable PE isolation film base film according to claim 1, characterized in that: The usage ratio of the core-shell microsphere powder, γ-aminopropyltriethoxysilane, anhydrous ethanol, deionized water and polyurethane fiber powder in step 2 is 50-60g: 20-30mL: 300-400mL: 800-900mL: 30-35g.

3. The method for preparing a heat-shrinkable PE isolation film base film according to claim 1, characterized in that: The modified titanium carbon spheres described in step 1 are prepared by the following steps: The hollow titanium carbon sphere powder and 1 mol / L nitric acid solution are added into a reactor in a dosage ratio of 20-25 g: 100-120 mL, and pickled for 1-1.2 h at 50-55°C and 400-500 r / min with stirring. The filter cake is washed with deionized water until the last washing liquid is neutral, and vacuum dried to obtain modified titanium carbon spheres.

4. The method for preparing a heat-shrinkable PE isolation film base film according to claim 1, characterized in that: The polyurethane fiber powder in step 2 is prepared by the following steps: Add polyurethane and dimethylformamide into the reactor in the ratio of 50-60g:200-300mL, stir at 20-25℃ and 400-500r / min for 30-40min, use pure water as coagulation bath for wet spinning, solidify for 30-40min, shear and crush to obtain polyurethane fiber powder with a length of 1-2mm.

5. The method for preparing a heat-shrinkable PE isolation film base film according to claim 1, characterized in that: The dosage ratio of the chitosan, nickel acetate, glacial acetic acid solution, gamma-polyglutamic acid, deionized water and tetrabutyl titanate is 20-30 g: 0.2-0.4 g: 200-300 mL: 15-20 g: 200-300 mL: 40-50 mL.

6. The method for preparing a heat-shrinkable PE isolation film base film according to claim 1, characterized in that: The dispersed nano-mica powder described in step 1 is prepared by the following steps: Add modified nano mica powder, stearic acid, xylene and n-butanol into a reaction kettle, stir at 20-25°C and 400-500 r / min for 1-2 hours, filter, wash the filter cake with deionized water 2-3 times, and vacuum dry to obtain dispersed nano mica powder; The usage ratio of the modified nano-mica powder, stearic acid, xylene and n-butanol is 15-20 g: 3-4 g: 80-90 mL: 100-120 mL.

7. The method for preparing a heat-shrinkable PE isolation film base film according to claim 6, characterized in that: The modified nano mica powder is prepared by the following steps: Adding modified mica powder and 50-60wt% ethanol solution into a reaction kettle, using an ultrasonic device to perform ultrasonic crushing for 2-3 hours at a power of 400W, then standing for 48-50 hours, filtering, washing the filter cake with deionized water for 2-3 times, and freeze-drying for 12-14 hours to obtain modified nano mica powder; The usage ratio of the modified mica powder and the ethanol solution is 20-22 g: 200-300 mL.

8. The method for preparing a heat shrinkage resistant PE isolation film base film according to claim 7, characterized in that: The modified mica powder is prepared by the following steps: Add crude mica powder, citric acid and deionized water into a reaction kettle, stir at 80-85°C and 400-500r / min for 3-4h, filter, wash the filter cake with deionized water until the last washing liquid is neutral, and vacuum dry to obtain modified mica powder; The usage ratio of the crude mica powder, citric acid and deionized water is 20-30 g: 40-50 g: 800-900 mL.

9. A heat shrinkage resistant PE isolation film base film, characterized in that: Prepared by the preparation method described in any one of claims 1 to 8.

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