Anti-ultraviolet elastomer film based on metal polyphenol network chemical modified mica nanosheet and preparation method of anti-ultraviolet elastomer film

Abstract

The invention provides an anti-ultraviolet elastomer film based on a metal polyphenol network chemical modified mica nanosheet and a preparation method of the anti-ultraviolet elastomer film. The anti-ultraviolet elastomer film comprises a compound of a metal polyphenol network chemical modified mica nanosheet and polyurethane, and the metal polyphenol network chemical modified mica nanosheet is composed of a mica nanosheet and a metal polyphenol network chemically modified on the surface of the mica nanosheet. The metal polyphenol network is a complex structure formed by combining and assembling plant polyphenols and metal ions through chemical interaction between the plant polyphenols and the metal ions, and the polyurethane and the metal polyphenol network chemical modified mica nanosheet form a layered brick mud structure on the microscopic scale. The uvioresistant polyurethane elastomer film with the bionic brick mud structure, which has an extremely strong shielding property in an ultraviolet region, is obtained, and a traditional ultraviolet shielding material does not have the uvioresistant polyurethane elastomer film.

Description

Technical Field

[0001] The present invention relates to the technical field of new material development, and particularly to an anti-ultraviolet elastomer film based on metal polyphenol network chemically modified mica nanosheets and a preparation method thereof. Background Art

[0002] With the progress of technology and the acceleration of the industrialization process, polyurethane (PU), as a high-performance material, has been widely used in many fields such as aerospace, automotive manufacturing, and building insulation due to its excellent mechanical properties, impact resistance, and fatigue resistance. However, during actual use, polyurethane is easily affected by ultraviolet radiation, moisture, and chemical media, resulting in a decline in its physical and chemical properties, thus limiting its service life in outdoor environments. Especially under long-term ultraviolet (UV) irradiation, the PU material will undergo photodegradation, showing aging phenomena such as yellowing, surface cracking, and a decline in mechanical properties. This not only affects the aesthetics and service life of the product but also may pose potential risks to the environment and human health. Ultraviolet rays are one of the main factors causing the aging of PU materials. When the PU material is irradiated with ultraviolet rays, photochemical reactions will occur, such as the Photo-Fries rearrangement reaction, leading to the breakage and crosslinking of molecular chains, thereby causing a significant decline in material properties. Polyurethane film is a non-toxic and harmless environmental protection material that does not cause any harm to human skin and is widely used in clothing fabrics, medical and health, food, leather, and other fields. Therefore, improving the anti-ultraviolet aging performance of polyurethane film materials is not only the key to enhancing their reliability and durability in outdoor environment applications but also an important research direction for promoting the application of polyurethane film materials in a wider range of fields. Summary of the Invention

[0003] The technical problem to be solved by the present invention is how to improve the anti-ultraviolet aging performance of polyurethane material films while also being more safe and non-toxic to broaden the uses of polyurethane film materials in many fields such as biomedical fields, food industry, environmental protection packaging materials, and clothing fabrics.

[0004] Therefore, the purpose of the present invention is to provide an anti-ultraviolet elastomer film based on metal polyphenol network chemically modified mica nanosheets and a preparation method thereof. This application uses a metal polyphenol network chemically modified mica nanosheet to modify polyurethane material to obtain an anti-ultraviolet elastomer film. This anti-ultraviolet elastomer film has excellent ultraviolet shielding performance, and the existence of the brick-mud structure and the intrinsic properties of polyurethane result in enhanced mechanical properties and good elasticity. The method adopted in this application combines the ultraviolet shielding mechanisms of plant polyphenols and mica. On the basis of the mica sheet shielding ultraviolet rays, the ultraviolet light irradiated on the mica surface will also be absorbed by the metal polyphenol network.

[0005] For this reason, this application provides the following aspects:

[0006] <1>. An ultraviolet-resistant elastomer film based on metal-polyphenol network chemically modified mica nanosheets, which comprises a composite of metal-polyphenol network chemically modified mica nanosheets and polyurethane, wherein the metal-polyphenol network chemically modified mica nanosheets are composed of mica nanosheets and a metal-polyphenol network chemically modified on the surface of the mica nanosheets, the metal-polyphenol network is formed by the combination and assembly of plant polyphenols and metal ions through their chemical interactions into a complex structure, and the polyurethane and the metal-polyphenol network chemically modified mica nanosheets form a layered brick-and-mortar structure at the microscale.

[0007] <2>. The ultraviolet-resistant elastomer film of the metal-polyphenol network chemically modified mica nanosheets according to <1>, wherein the thickness range of the ultraviolet-resistant elastomer film is 20 - 1000 μm.

[0008] <3>. The ultraviolet-resistant elastomer film of the metal-polyphenol network chemically modified mica nanosheets according to any one of the above, wherein the thickness range of the metal-polyphenol network chemically modified mica nanosheets is 0.3 - 100 nm, and the sheet diameter range is 50 - 10000 nm.

[0009] <4>. The ultraviolet-resistant elastomer film of the metal-polyphenol network chemically modified mica nanosheets according to any one of the above, wherein the modification amount of the metal-polyphenol network accounts for 10% - 50% of the mass of the mica nanosheets.

[0010] <5>. The ultraviolet-resistant elastomer film of the metal-polyphenol network chemically modified mica nanosheets according to any one of the above, wherein the metal-polyphenol network chemically modified mica nanosheets have an absorbance higher than 1 in the ultraviolet band of 200 - 400 nm in the ultraviolet-visible absorption spectrum, or a transmittance lower than 50% in the 200 - 400 nm band in the ultraviolet transmittance spectrum.

[0011] <6>. The ultraviolet-resistant elastomer film of the metal-polyphenol network chemically modified mica nanosheets according to any one of the above, wherein the molar ratio between the plant polyphenols and the metal ions is in the range of 1:3 - 4:1.

[0012] <7>. The ultraviolet-resistant elastomer film of the metal-polyphenol network chemically modified mica nanosheets according to any one of the above, wherein the plant polyphenols are selected from one or more of tannic acid and tea polyphenols.

[0013] <8>. The ultraviolet-resistant elastomer film of the metal-polyphenol network chemically modified mica nanosheets according to any one of the above, wherein the metal ions are selected from Cu 2+ 、Fe 3+ 、Mg 2+ 、Ca 2+, Zn 2+ and Mn 2+ one or more of the following.

[0014] <9>. The anti-ultraviolet elastomer film of the metal polyphenol network chemically modified mica nanosheets according to any one of the above, wherein the mass ratio of the metal polyphenol network chemically modified mica nanosheets to the polyurethane is 1:9 - 1:1.

[0015] <10>. A method for preparing the anti-ultraviolet elastomer film of the metal polyphenol network chemically modified mica nanosheets according to any one of claims <1> - <9>, the method comprising the following steps:

[0016] A) Provide a suspension of exfoliated mica nanosheets in water;

[0017] B) Add plant polyphenols accounting for 10% - 50% of the mass of the mica nanosheets to the mica nanosheet suspension to obtain a mixture of mica nanosheets and plant polyphenols;

[0018] C) Add metal ions to the mixture, and the molar ratio between the plant polyphenols and the metal ions is between 1:3 - 4:1;

[0019] D) Adjust the pH of the mixture of mica nanosheets, plant polyphenols and metal ions obtained in step C) to be weakly alkaline to complex the plant polyphenols and metal ions to obtain metal polyphenol network chemically modified mica nanosheets;

[0020] E) Mix the metal polyphenol network chemically modified mica nanosheets obtained in step D) and polyurethane in a mass ratio of 1:9 - 1:1 to obtain a mixture;

[0021] F) Assemble and dry the mixture obtained in step E) by solvent evaporation-induced self-assembly to obtain the anti-ultraviolet elastomer film.

[0022] <11>. The method according to <10>, wherein the raw material of the mica nanosheets is selected from one or more of phlogopite or muscovite.

[0023] <12>. The method according to <10>, wherein in step C), the plant polyphenols and metal ions are complexed under conventional reaction conditions.

[0024] <13>. The method according to <10>, wherein in step D), the pH is adjusted by a buffer system, and the buffer system is selected from one of phosphate buffer (PBS), tris(hydroxymethyl)aminomethane-hydrochloric acid buffer (Tris-HCl), 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) or 3-(N-morpholino)propanesulfonic acid (MOPS). Description of the Drawings

[0025] Figure 1 This is a photograph of the aqueous dispersion of mica nanosheets modified by tannin-manganese ion network prepared in Example 1 of the present invention. The obtained aqueous dispersion of mica nanosheets modified by tannin-manganese ion network is a homogeneous, transparent, light yellow dispersion;

[0026] Figure 2 This is a micrograph of the mica nanosheets modified by tannin-manganese ion network prepared in Example 1 of the present invention observed under a field emission scanning electron microscope. It can be seen that the mica nanosheets modified by tannin-manganese ion network are on the nanoscale;

[0027] Figure 3 This is the particle size distribution of the mica nanosheets prepared in Example 1 of the present invention obtained by dynamic light scattering test and Gaussian fitting. It can be seen that most of the sizes of the mica nanosheets modified by tannin-manganese ion network are in the range of 50 - 100 nm;

[0028] Figure 4 This is the ultraviolet absorption spectra of tannin, manganese chloride and tannin-manganese ion complex in Example 1 of the present invention. It can be seen that after the complexation of tannin and manganese ions, the ultraviolet absorption spectrum is significantly red-shifted, proving the formation of this complex structure.

[0029] Figure 5 This is the ultraviolet absorption spectra of the aqueous dispersions of mica nanosheets before and after being modified by tannin and tannin-manganese ion network prepared in Example 1 of the present invention. The absorption of the mica nanosheets modified by tannin in the ultraviolet band is significantly enhanced, and the absorption of the mica nanosheets modified by tannin-manganese ion network in the ultraviolet band is further enhanced, preliminarily proving that the mica modified by this method has good ultraviolet shielding performance;

[0030] Figure 6 This is the infrared spectra of tannin, mica nanosheets and mica nanosheets modified by tannin-manganese ion network prepared in Example 1 of the present invention, proving the successful modification of tannin;

[0031] Figure 7 This is the X-ray photoelectron spectra of the mica nanosheets before and after being modified by tannin-manganese ion network prepared in Example 1 of the present invention, also proving the successful modification of tannin;

[0032] Figure 8 This is the inductively coupled plasma emission spectra of the mica nanosheets before and after being modified by tannin-manganese ion network prepared in Example 1 of the present invention, proving the successful complexation of tannin and Mn 2+ ;

[0033] Figure 9The ultraviolet transmittance spectrum of the elastomer film formed by the tannin-manganese ion network-modified phlogopite nanosheets and polyurethane prepared in Example 1 of the present invention. It can be seen that the transmittance of this film in the ultraviolet light band of 200 - 400 nm is very low, less than 20%, and it has good ultraviolet shielding properties;

[0034] Figure 10 The digital photo of the film formed by the tannin-manganese ion network-modified phlogopite and polyurethane prepared in Example 1 of the present invention;

[0035] Figure 11 The SEM of the elastomer film formed by the tannin-manganese ion network-modified phlogopite and polyurethane prepared in Example 1 of the present invention. It can be seen that a very obvious layered brick-and-mortar structure;

[0036] Figure 12 The mechanics of the anti-ultraviolet elastomer film formed by the tannin-manganese ion network-modified phlogopite (mass fraction 30%) and polyurethane (mass fraction 70%) prepared in Example 1 of the present invention. It can be seen that compared with pure polyurethane, the prepared anti-ultraviolet polyurethane elastomer has higher tensile strength and elongation at break;

[0037] Figure 13 The ultraviolet absorption spectrum of the phlogopite nanosheet aqueous dispersion before and after being modified by the tannin-iron ion network prepared in Example 2 of the present invention. It can be seen that the absorption of the phlogopite nanosheets modified by the tannin-iron ion network in the ultraviolet band is significantly enhanced, and the absorbance in the ultraviolet light band of 200 - 300 nm is higher than 1;

[0038] Figure 14 The ultraviolet transmittance spectrum of the elastomer film formed by the tannin-iron ion network-modified phlogopite nanosheets and polyurethane prepared in Example 2 of the present invention. It can be seen that the transmittance of this film in the ultraviolet light band of 200 - 400 nm is less than 40%, and the transmittance in the band of 200 - 350 nm is close to 0, which indicates that it has good ultraviolet shielding properties;

[0039] Figure 15 The SEM of the elastomer film formed by the tannin-iron ion network-modified phlogopite and polyurethane prepared in Example 2 of the present invention. Similarly, a very obvious layered brick-and-mortar structure can be seen;

[0040] Figure 16 The mechanics of the tannin-iron ion network-modified phlogopite (mass fraction 30%) and polyurethane (mass fraction 70%) prepared in Example 2 of the present invention. Similarly, it also has enhanced tensile strength and elongation at break;

[0041] Figure 17The ultraviolet absorption spectra of the phlogopite nanosheet aqueous dispersion before and after the modification of the tea polyphenol manganese ion network prepared in Example 3 of the present invention are shown. It can be seen that the absorption of the phlogopite nanosheets after the modification of the tea polyphenol manganese ion network in the ultraviolet band is significantly enhanced;

[0042] Figure 18 The ultraviolet transmittance spectra of the elastomeric membrane formed by the phlogopite nanosheets modified with the tea polyphenol manganese ion network and polyurethane prepared in Example 3 of the present invention are shown. It can be seen that the transmittance of this membrane in the 200 - 800 nm band is very low, less than 40%, and the transmittance in the 200 - 400 nm band is close to 0, indicating good ultraviolet shielding properties;

[0043] Figure 19 The SEM of the elastomeric membrane formed by the phlogopite modified with the tea polyphenol manganese ion network and polyurethane prepared in Example 3 of the present invention is shown. Similarly, a very obvious layered brick - mud structure can be seen;

[0044] Figure 20 The mechanical properties of the phlogopite (mass fraction 30%) modified with the tea polyphenol manganese ion network and polyurethane (mass fraction 70%) prepared in Example 3 of the present invention are shown. It also has enhanced fracture strength and elongation at break;

[0045] Figure 21 The ultraviolet absorption spectra of the muscovite nanosheet aqueous dispersion before and after the modification of the tannin manganese ion network prepared in Example 4 of the present invention are shown. It can be seen that the absorption of the muscovite nanosheets after the modification of the tannin manganese ion network in the ultraviolet band is significantly enhanced;

[0046] Figure 22 The ultraviolet transmittance spectra of the elastomeric membrane formed by the muscovite nanosheets modified with the tannin manganese ion network and polyurethane prepared in Example 4 of the present invention are shown. It can be seen that the transmittance of this membrane in the 200 - 800 nm band is very low, less than 30%, and the transmittance in the 200 - 400 nm band is close to 0, indicating good ultraviolet shielding properties;

[0047] Figure 23 The SEM of the elastomeric membrane formed by the muscovite modified with the tannin manganese ion network and polyurethane prepared in Example 4 of the present invention is shown. Similarly, a very obvious layered brick - mud structure can be seen;

[0048] Figure 24 The mechanical properties of the muscovite (mass fraction 30%) modified with the tannin manganese ion network and polyurethane (mass fraction 70%) prepared in Example 4 of the present invention are shown. It also has enhanced fracture strength and elongation at break. Detailed implementation manners

[0049] In view of the characteristics of mica nanosheets, plant polyphenols and polyurethane themselves, as well as the current situation of traditional ultraviolet protection materials, the present application provides an anti-ultraviolet elastomer film based on metal polyphenol network chemically modified mica nanosheets. The anti-ultraviolet elastomer film of the present application comprises a composite of metal polyphenol network chemically modified mica nanosheets and polyurethane, wherein the metal polyphenol network chemically modified mica nanosheets are composed of mica nanosheets and a metal polyphenol network chemically modified on the surface of the mica nanosheets, and the metal polyphenol network is assembled into a complex structure by the chemical interaction between plant polyphenols and metal ions, and the polyurethane and the metal polyphenol network chemically modified mica nanosheets form a layered brick-and-mortar structure at the microscale. The metal polyphenol network modified ultraviolet-shielding mica nanosheets have an absorbance greater than 1 in the 200-400 nm band of the ultraviolet-visible absorption spectrum, or a transmittance lower than 50% in the 200-400 nm band of the ultraviolet transmittance spectrum.

[0050] In the anti-ultraviolet elastomer film of the present application, the mass ratio of the metal polyphenol network chemically modified mica nanosheets to polyurethane is in the range of 1:9 - 1:1, more preferably in the range of 1:4 - 2:3, and still more preferably in the range of 1:4 - 3:7.

[0051] In the present application, as a raw material, plant polyphenols can absorb ultraviolet rays in the 200 to 350 nm nanometer band due to their aromatic ring and conjugated double bond structures and convert them into heat energy for release, while mica flakes as raw materials usually have ultraviolet shielding in the 200 - 300 nm nanometer band. However, the metal polyphenol network modified ultraviolet-shielding mica nanosheets obtained in the present invention have an absorbance higher than 1 in the ultraviolet band of the ultraviolet-visible absorption spectrum of 200 - 400 nm, or a transmittance lower than 50% in the 200 - 400 nm band of the ultraviolet transmittance spectrum.

[0052] In the metal polyphenol network chemically modified mica of the present application, the molar ratio between the plant polyphenols and the metal ions is in the range of 1:3 - 4:1, more preferably in the range of 1:2 - 3:1, and still more preferably in the range of 1:1 - 2:1. The addition amount of the metal polyphenol network accounts for 10% - 50% of the mass of the mica nanosheets, preferably 10% - 40%, and more preferably 10% - 30%.

[0053] In the present application, the term "metal polyphenol network" means a complex structure formed by the chemical interaction between plant polyphenols and metal ions.

[0054] In the present application, the term "mica nanosheets" means nanosheet layers peeled from natural mica minerals.

[0055] In the present application, the term "ultraviolet shielding" means having a high absorbance greater than 1 in the ultraviolet-visible absorption spectrum in the wavelength range of 200 - 400 nm, or having a low transmittance lower than 50% in the ultraviolet transmittance spectrum in the wavelength range of 200 - 400 nm, so as to be able to block ultraviolet rays.

[0056] In the present application, an elastomer refers to a material that can quickly return to its original shape after being stressed and has an extremely high elongation at break and flexibility. The polyurethane used in the present application is an elastomer.

[0057] Preferably, the plant polyphenol is selected from one or more of tannic acid and tea polyphenols.

[0058] Preferably, the metal ion is selected from Cu 2+ , Fe 3+ , Mg 2+ , Ca 2+ , Zn 2+ and Mn 2+ selected from one or more of them.

[0059] For the mica nanosheets of the present application, the thickness ranges from 0.3 - 100 nm, preferably from 0.6 - 10 nm, more preferably from 1 - 5 nm; the sheet diameter (i.e., diameter) ranges from 50 - 10000 nm, preferably from 60 - 800 nm, more preferably from 100 - 500 nm.

[0060] For the ultraviolet-resistant elastomer film of the metal polyphenol network chemically modified mica nanosheets of the present application, the thickness ranges from 100 - 1000 μm, preferably from 200 - 800 μm, more preferably from 200 - 400 μm.

[0061] In the ultraviolet-resistant elastomer film of the metal polyphenol network chemically modified mica nanosheets of the application, other conventional additives suitable for performance modification may also be included.

[0062] This application first provides that the anti-ultraviolet elastomer film obtained based on the metal polyphenol network chemically modified mica nanosheets can be obtained by compounding the metal polyphenol network modified mica nanosheets and polyurethane. In this application, the ultraviolet-shielding mica nanosheets modified by the metal polyphenol network have ultraviolet-shielding effects at multiple scales; the mica nanosheets have a polarization effect and an interference effect due to their unique layered structure at the nanoscale, and can effectively block or scatter ultraviolet rays, thereby exhibiting excellent ultraviolet-shielding performance; at the molecular scale, the plant polyphenols contain aromatic rings and conjugated double bond structures inside their molecules, and these structural features enable the plant polyphenols to absorb ultraviolet rays in the 200-350 nm band and convert the absorbed ultraviolet energy into heat energy and release it; when the plant polyphenols form complexes with metal ions, due to the change of the chemical environment, the absorption peak in the ultraviolet-visible spectral region redshifts, further broadening the absorption range of ultraviolet rays and enhancing the overall ultraviolet-shielding ability. In the anti-ultraviolet elastomer film provided by this application, the existence of the brick-mud structure and the intrinsic properties of polyurethane result in enhanced mechanical properties and good elasticity.

[0063] On the other hand, this application also provides a preparation method of an anti-ultraviolet elastomer film based on the metal polyphenol network chemically modified mica nanosheets, including the following steps:

[0064] A) Provide a suspension of exfoliated mica nanosheets in water;

[0065] B) Add plant polyphenols with a mass fraction of 10%-50% of the mica nanosheets to the mica nanosheet suspension obtained in step A);

[0066] C) Add metal ions to the mixture of mica nanosheets and plant polyphenols obtained in step B), and the molar ratio between the plant polyphenols and the metal ions is between 1:3 and 4:1;

[0067] D) Adjust the pH of the mixture of mica nanosheets, plant polyphenols and metal ions obtained in step C) to be weakly alkaline to complex the plant polyphenols and metal ions, and obtain the metal polyphenol network chemically modified mica nanosheets;

[0068] E) Mix the modified mica obtained in step D) and polyurethane, and make the modified mica film and polyurethane fully and uniformly mixed by ultrasonic dispersion;

[0069] F) Assemble and dry the mixture of the modified mica and polyurethane obtained in step E) by the method of solvent evaporation-induced self-assembly to obtain the anti-ultraviolet polyurethane elastomer film.

[0070] As an example, step A) includes: uniformly dispersing mica raw materials in water, performing exfoliation treatment with the assistance of ultrasonic waves, then centrifuging at a rotation speed of 2000 - 5000 r / min for 10 - 20 min, and taking the centrifuged supernatant to obtain a mica nanosheet suspension. The reason why mica flakes can be exfoliated by ultrasound is that there are K with balanced negative charges between mica layers + , resulting in weak bonding between mica layers and being easily exfoliated under external forces such as ultrasound. More specifically, the mica includes but is not limited to phlogopite, and can also be other micas such as muscovite.

[0071] Preferably, the mica raw material is selected from one or more of phlogopite or muscovite.

[0072] Preferably, the plant polyphenol and metal ions undergo a complexation reaction under conventional reaction conditions.

[0073] Preferably, the buffer system for adjusting pH is selected from one of phosphate buffer (PBS), tris(hydroxymethyl)aminomethane - hydrochloric acid buffer (Tris - HCl), 4 - (2 - hydroxyethyl)piperazine - 1 - ethanesulfonic acid (HEPES), and 3 - morpholinopropanesulfonic acid (MOPS).

[0074] A weakly alkaline pH refers to a pH of 7.1 - 10.0, preferably 7.5 - 9.0, and more preferably 8.0 - 8.5.

[0075] For the anti - ultraviolet elastomer film of the metal polyphenol network - chemically modified mica nanosheets of the present application, the drying temperature range in step F) is 30 - 100 °C, preferably 40 - 80 °C, and more preferably 60 - 70 °C.

[0076] In the present invention, the term "solvent evaporation-induced self-assembly" refers to a material preparation technique that drives the self-assembly of nanoparticles or molecules into ordered structures through solvent evaporation. Examples thereof include utilizing the concentration gradient and surface tension changes during the evaporation process to guide the arrangement of nanomaterials. For example, when preparing an ordered nanocomposite film, a mixed solution containing nanoparticles and a polymer is placed in a controlled environment. As the solvent gradually evaporates, the interaction between the nanoparticles and the polymer chains increases, prompting them to spontaneously form a layered arrangement similar to a brick-and-mortar structure. This technique has been widely used in the preparation of composite materials with enhanced mechanical properties, improved optical characteristics, or increased thermal stability. Through the method of solvent evaporation-induced self-assembly, in the formed thin film, polyurethane and metal polyphenol network chemically modified mica nanosheets form a brick-and-mortar structure at the microscale. The brick-and-mortar structure is a structural design that mimics biomaterials in nature and achieves good strength-ductility matching through the stacking of hard and soft phases. The brick-and-mortar structure is usually composed of alternating stacks of hard "bricks" and soft "mortar", similar to the brick wall and mortar in construction. Due to its design of alternating hard and soft phase stacks, this structure enables the hard phase to provide strength and the soft phase to absorb and disperse stress, thereby achieving a balance of strength and toughness. When a crack encounters the alternating interface of hard and soft phases during propagation, it will deflect, increasing the crack propagation path and improving the toughness of the material. The presence of the brick-and-mortar structure and the intrinsic properties of polyurethane result in enhanced mechanical properties and better elasticity.

[0077] In summary, the preparation method of the present application provides an anti-ultraviolet elastomer film based on metal polyphenol network chemically modified mica nanosheets and a preparation method thereof. Such a film according to the present application can be obtained by modifying ultrasonically exfoliated mica nanosheets with a metal polyphenol network and then compositing the modified mica and polyurethane into a film. The metal polyphenol network modified ultraviolet-shielding mica nanosheets have ultraviolet-shielding effects at multiple scales. The ultraviolet shielding of mica nanosheets at the nanoscale and the ultraviolet absorption of the metal polyphenol network at the molecular scale work together to endow the metal polyphenol network modified ultraviolet-shielding mica nanosheets with extremely high ultraviolet-shielding efficiency. In addition, in the anti-ultraviolet elastomer film of the present application, the presence of the brick-and-mortar structure and the intrinsic properties of polyurethane result in enhanced mechanical properties and better elasticity, which are not possessed by traditional polyurethane materials. Therefore, the anti-ultraviolet elastomer film based on metal polyphenol network chemically modified mica nanosheets provided by the present application has high ultraviolet-shielding ability, enhanced mechanical properties, and strong elasticity, and is a strong competitor to traditional polyurethane materials on the market.

[0078] Examples

[0079] To further understand the present invention, the anti-ultraviolet elastomer film of metal polyphenol network chemically modified mica nanosheets provided by the present invention will be described in detail below in conjunction with embodiments. The protection scope of the present invention is not limited by the following embodiments.

[0080] All the reagents appearing in the following embodiments are commercially available reagents and are directly used without special treatment. In addition, the process of ultraviolet absorption spectrum test involved in this application is as follows: Dilute the total concentration of the prepared dispersion to 0.2 mg / mL, take 3 mL and place it in a cuvette, and use a Shimadzu UV-2600 ultraviolet-visible spectrophotometer made in Japan for testing. The process of ultraviolet transmittance spectrum test involved in this application is as follows: Use a Shimadzu Solid 3700DUV ultraviolet-visible near-infrared spectrophotometer made in Japan to test the prepared film.

[0081] Example 1

[0082] A) Disperse phlogopite raw materials in water. Under the action of ultrasonic waves, exfoliate phlogopite into phlogopite nanosheets, and then centrifuge at a speed of 3000 r / min for 10 min. Take the centrifuged supernatant to obtain a phlogopite nanosheet suspension;

[0083] B) Add tannic acid with a mass fraction of 16% of the phlogopite nanosheets to the phlogopite nanosheet suspension obtained in step A), and stir evenly;

[0084] C) Add manganese chloride with a molar content close to that of tannic acid to the mixture of phlogopite nanosheets and tannic acid obtained in step B), and stir evenly to obtain a water dispersion of tannin-modified phlogopite nanosheets;

[0085] D) Adjust the pH of the mixture of phlogopite nanosheets, tannic acid and manganese chloride obtained in step C) to 8.0 with 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) buffer solution to complex tannic acid and manganese ions;

[0086] E) Mix the modified phlogopite nanosheets obtained in step D) with polyurethane (the mass ratio of mica to polyurethane is 3:7), and ultrasonically disperse for 2 min to fully and evenly mix the modified mica film and polyurethane to obtain a water dispersion of tannin manganese ion network modified phlogopite nanosheets;

[0087] F) Assemble the water dispersion of the tannin manganese ion network modified phlogopite nanosheets obtained in step E) and the mixture of polyurethane by solvent evaporation-induced self-assembly method and dry at 60 °C to obtain an anti-ultraviolet polyurethane elastomer film.

[0088] Figure 1This is a photograph of the aqueous dispersion of mica nanosheets modified by tannin-manganese ion network prepared in Example 1 of the present invention. The obtained aqueous dispersion of mica nanosheets modified by tannin-manganese ion network is a uniform, transparent and light yellow dispersion;

[0089] Figure 2 This is a microscopic photograph of the mica nanosheets modified by tannin-manganese ion network prepared in Example 1 of the present invention observed under a field emission scanning electron microscope. It can be seen that the mica nanosheets modified by tannin-manganese ion network are of nanoscale;

[0090] Figure 3 This is the sheet diameter distribution of the mica nanosheets prepared in Example 1 of the present invention obtained by dynamic light scattering test and Gaussian fitting. It can be seen that the sheet diameter of the mica nanosheets modified by tannin-manganese ion network is mostly in the range of 50 - 100 nm;

[0091] Figure 4 This is the ultraviolet absorption spectrum of tannin, manganese chloride and tannin-manganese ion complex in Example 1 of the present invention. It can be seen that after the complexation of tannin and manganese ions, the ultraviolet absorption spectrum is significantly red-shifted, proving the formation of this complex structure;

[0092] Figure 5 This is the ultraviolet absorption spectrum of the aqueous dispersion of mica nanosheets before and after being modified by tannin and tannin-manganese ion network prepared in Example 1 of the present invention. It can be seen that the absorption of the mica nanosheets modified by tannin in the ultraviolet band is significantly enhanced, while the absorption of the mica nanosheets modified by tannin-manganese ion network in the ultraviolet band is further significantly enhanced and a red shift also appears, proving that tannin and manganese ions form a complex on the surface of mica nanosheets, and preliminarily proving that the mica modified by this method can have good ultraviolet shielding performance;

[0093] Figure 6 This is the infrared spectrum of tannin, mica nanosheets and mica nanosheets modified by tannin-manganese ion network prepared in Example 1 of the present invention. From the infrared spectrum of the modified mica, it can be seen that the absorption peak at 1734 cm -1 is the stretching vibration of the carbonyl double bond in the ester group of tannin, and the absorption peak at 1189 cm -1 corresponds to the vibration of the carbon-oxygen single bond in tannin, and the absorption peak at 1650 - 1430 cm -1 corresponds to the skeletal vibration of the benzene ring in tannin. This proves the successful modification of tannin;

[0094] Figure 7 This is the X-ray photoelectron spectrum of the mica nanosheets before and after being modified by tannin-manganese ion network prepared in Example 1 of the present invention. It can be seen that the carbon element content of the mica nanosheets after modification increases significantly, which also proves the successful modification of tannin;

[0095] Figure 8For the inductively coupled plasma emission spectrum of phlogopite nanosheets before and after the preparation of the tannin-manganese ion network modification in Example 1 of the present invention, it can be seen that the Mn content in the modified phlogopite nanosheets increases significantly, proving the successful complexation of tannin and Mn; 2+ content increases significantly, proving the successful complexation of tannin and Mn; 2 + ;

[0096] Figure 9 For the ultraviolet transmittance spectrum of the elastomer film formed by the tannin-manganese ion network-modified phlogopite nanosheets and polyurethane prepared in Example 1 of the present invention, it can be seen that pure polyurethane has a high transmittance in the ultraviolet light band, and the transmittance in some bands even exceeds 80%. In contrast, the ultraviolet-resistant film of the present application has a very low transmittance in the ultraviolet light band, and the transmittance in the 200 - 350 nm band is less than 1%, having good ultraviolet shielding property;

[0097] Figure 10 Digital photo of the film formed by the tannin-manganese ion network-modified phlogopite and polyurethane prepared in Example 1 of the present invention;

[0098] Figure 11 SEM of the tannin-manganese ion network-modified phlogopite and polyurethane prepared in Example 1 of the present invention, and a very obvious layered brick-mud structure can be seen;

[0099] Figure 12 For the mechanical properties of the ultraviolet-resistant polyurethane elastomer film formed by the tannin-manganese ion network-modified phlogopite (mass fraction 30%) and polyurethane (mass fraction 70%) prepared in Example 1 of the present invention, it can be seen that compared with the pure polyurethane film, the ultraviolet-resistant polyurethane elastomer film prepared in this example has higher tensile strength and elongation at break, and is mechanically similar to the film formed by tannin-modified phlogopite (mass fraction 30%) and polyurethane (mass fraction 70%).

[0100] Example 2

[0101] A) Disperse the phlogopite raw material in water. Under the action of ultrasonic waves, exfoliate the phlogopite into phlogopite nanosheets, and then centrifuge at a speed of 3000 r / min for 10 min. Take the centrifuged supernatant to obtain a phlogopite nanosheet suspension;

[0102] B) Add tannic acid with a mass fraction of 16% of the phlogopite nanosheets to the phlogopite nanosheet suspension obtained in step A), and stir evenly;

[0103] C) Add ferric chloride with a molar content close to that of tannic acid to the mixture of phlogopite nanosheets and tannic acid obtained in step B), and stir evenly;

[0104] D) Adjust the pH of the mixed solution of phlogopite nanosheets, tannic acid and ferric chloride obtained in step C) to 8.0 with HEPES buffer solution to complex tannic acid and iron ions, and obtain an aqueous dispersion of phlogopite nanosheets modified by tannic iron ion network;

[0105] E) Mix the aqueous dispersion of phlogopite nanosheets modified by tannic iron ion network obtained in step D) with polyurethane (the mass ratio of mica to polyurethane is 3:7), and ultrasonically disperse for 2 min to fully and uniformly mix the modified mica film and polyurethane;

[0106] F) Assemble the mixed solution of the modified mica and polyurethane obtained in step E) by solvent evaporation-induced self-assembly method and dry it at 60 °C to obtain an anti-ultraviolet polyurethane elastomer film;

[0107] Figure 13 The ultraviolet absorption spectra of the aqueous dispersions of phlogopite nanosheets before and after modification by tannic iron ion network prepared in Example 2 of the present invention are shown. It can be seen that the absorption of phlogopite nanosheets after modification by tannic iron ion network in the ultraviolet band is significantly enhanced, indicating that iron ions can also be used in the modification method of metal polyphenol network;

[0108] Figure 14 The ultraviolet transmittance spectra of the elastomer film formed by the phlogopite nanosheets modified by tannic iron ion network and polyurethane prepared in Example 2 of the present invention are shown. It can be seen that the transmittance of this film in the ultraviolet light band of 200-400 nm is lower than 40%, and the transmittance in the band of 200-350 nm is close to 0, indicating that it has good ultraviolet shielding performance;

[0109] Figure 15 The SEM of the elastomer film formed by the phlogopite modified by tannic iron ion network and polyurethane prepared in Example 2 of the present invention is shown. It can also be seen that there is a very obvious layered brick-mud structure;

[0110] Figure 16 The mechanical properties of the anti-ultraviolet polyurethane elastomer film formed by the phlogopite modified by tannic iron ion network (mass fraction 30%) and polyurethane (mass fraction 70%) prepared in Example 2 of the present invention are shown. It also has enhanced tensile strength and elongation at break, and is close to that of the film formed by the phlogopite modified by tannin (mass fraction 30%) and polyurethane (mass fraction 70%).

[0111] Example 3

[0112] A) Disperse the phlogopite raw material in water, and under the action of ultrasonic waves, exfoliate the phlogopite into phlogopite nanosheets, then centrifuge at a speed of 3000 r / min for 10 min, and take the centrifuged supernatant to obtain a phlogopite nanosheet suspension;

[0113] B) Add tea polyphenols accounting for 16% of the mass of phlogopite nanosheets to the phlogopite nanosheet suspension obtained in step A), and stir and mix evenly;

[0114] C) Add manganese chloride with a molar content close to that of tea polyphenols to the mixture of phlogopite nanosheets and tea polyphenols obtained in step B), and stir and mix evenly;

[0115] D) Adjust the pH of the mixture of phlogopite nanosheets, tea polyphenols and manganese chloride obtained in step C) to 8.0 with 2-(4-(2-Hydroxyethyl)piperazin-1-yl)ethanesulfonic acid (HEPES) buffer solution to complex tea polyphenols and manganese ions, and obtain a water dispersion of phlogopite nanosheets modified by a tea polyphenol-manganese ion network;

[0116] E) Mix the water dispersion of phlogopite nanosheets modified by the tea polyphenol-manganese ion network obtained in step D) with polyurethane (the mass ratio of mica to polyurethane is 3:7), and ultrasonically disperse for 2 min to fully and evenly mix the modified mica film and polyurethane;

[0117] F) Assemble the mixture of the modified mica and polyurethane obtained in step E) by solvent evaporation-induced self-assembly method and dry at 60 °C to obtain an anti-ultraviolet polyurethane elastomer film.

[0118] Figure 17 This is the ultraviolet absorption spectrum of the water dispersion of phlogopite nanosheets before and after being modified by the tea polyphenol-manganese ion network prepared in Example 3 of the present invention. It can be seen that the absorption of the phlogopite nanosheets after being modified by the tea polyphenol-manganese ion network is also significantly enhanced in the ultraviolet band, indicating that tea polyphenols can also be used in the modification method of metal polyphenol networks;

[0119] Figure 18 This is the ultraviolet transmittance spectrum of the elastomer film formed by the phlogopite nanosheets modified by the tea polyphenol-manganese ion network and polyurethane prepared in Example 3 of the present invention. It can be seen that the transmittance of this film in the 200 - 800 nm band is very low, lower than 40%, and the transmittance in the 200 - 400 nm band is close to 0, indicating good ultraviolet shielding performance;

[0120] Figure 19 This is the SEM of the elastomer film formed by the phlogopite modified by the tea polyphenol-manganese ion network and polyurethane prepared in Example 3 of the present invention. Similarly, a very obvious layered brick-and-mud structure can be seen;

[0121] Figure 20 This is the mechanics of the phlogopite modified by the tea polyphenol-manganese ion network (mass fraction 30%) and polyurethane (mass fraction 70%) prepared in Example 3 of the present invention. It also has enhanced tensile strength and elongation at break, and the mechanics is close to that of the film formed by the phlogopite modified by tea polyphenols (mass fraction 30%) and polyurethane (mass fraction 70%).

[0122] Example 4

[0123] A) Disperse the muscovite raw material in water. Under the action of ultrasound, exfoliate the muscovite into muscovite nanosheets, then centrifuge at a speed of 3000 r / min for 10 min, and take the centrifuged supernatant to obtain a muscovite nanosheet suspension;

[0124] B) Add tannic acid with a mass fraction of 16% of the muscovite nanosheets to the muscovite nanosheet suspension obtained in step A), and stir evenly;

[0125] C) Add manganese chloride with a molar content close to that of tannic acid to the mixture of muscovite nanosheets and tannic acid obtained in step B), and stir evenly;

[0126] D) Adjust the pH of the mixture of muscovite nanosheets, tannic acid and manganese chloride obtained in step C) to 8.0 with 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) buffer solution to complex tannic acid and manganese ions, and obtain a water dispersion of muscovite nanosheets modified by tannin-manganese ion network;

[0127] E) Mix the modified mica obtained in step D) with polyurethane (the mass ratio of mica to polyurethane is 3:7), and ultrasonically disperse for 2 min to make the modified mica film and polyurethane fully and evenly mixed;

[0128] F) Assemble the mixture of the modified mica and polyurethane obtained in step E) by solvent evaporation-induced self-assembly method and dry at 60 °C to obtain an anti-ultraviolet polyurethane elastomer film.

[0129] Figure 21 This is the ultraviolet absorption spectrum of the water dispersion of muscovite nanosheets modified by tannin-manganese ion network prepared in Example 4 of the present invention. It can be seen that the absorption of the muscovite nanosheets modified by tannin-manganese ion network in the ultraviolet band is significantly enhanced, indicating that this modification method is not limited by the type of mica;

[0130] Figure 22 This is the ultraviolet transmittance spectrum of the elastomer film formed by the muscovite nanosheets modified by tannin-manganese ion network and polyurethane prepared in Example 4 of the present invention. It can be seen that the transmittance of this film in the 200 - 800 nm band is very low, lower than 30%, and the transmittance in the 200 - 500 nm band is close to 0, indicating good ultraviolet shielding performance;

[0131] Figure 23 This is the SEM of the elastomer film formed by the muscovite modified by tannin-manganese ion network and polyurethane prepared in Example 4 of the present invention. Similarly, a very obvious layered brick-mud structure can be seen;

[0132] Figure 24The mechanical properties of the muscovite (mass fraction 30%) and polyurethane (mass fraction 70%) modified by tannin-manganese ion network prepared in Example 4 of the present invention also have enhanced fracture strength and elongation at break, and are close to those of the film formed by muscovite (mass fraction 30%) and polyurethane (mass fraction 70%) modified by tannin.

[0133] The above description of the disclosed embodiments is intended to enable those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the scope of protection of the present invention will not be limited to these embodiments shown herein, but will be broadly interpreted by the appended claims.

Claims

1. An anti-ultraviolet elastomeric film based on metal polyphenol network chemically modified mica nanosheets, which includes a composite of metal polyphenol network chemically modified mica nanosheets and polyurethane, wherein the metal polyphenol network chemically modified mica nanosheets are composed of mica nanosheets and a metal polyphenol network chemically modified on the surface of the mica nanosheets, the metal polyphenol network is a complex structure formed by the combination and assembly of plant polyphenols and metal ions through chemical interactions therebetween, and the polyurethane and the metal polyphenol network chemically modified mica nanosheets form a layered brick-mud structure on a microscopic scale.

2. The UV-resistant elastic film of metal polyphenol network chemically modified mica nanosheets according to claim 1, wherein: The thickness of the anti-ultraviolet elastic film ranges from 20 to 1000 μm.

3. The UV-resistant elastic film of metal polyphenol network chemically modified mica nanosheets according to claim 1, wherein: The metal polyphenol network chemically modified mica nanosheets have a thickness range of 0.3-100 nm and a sheet diameter range of 50-10000 nm.

4. The UV-resistant elastomeric film of mica nanosheets chemically modified with a metal polyphenol network according to claim 1, wherein the modification amount of the metal polyphenol network accounts for 10%-50% of the mass of the mica nanosheets.

5. The UV-resistant elastomeric film of metal polyphenol network chemically modified mica nanosheets according to claim 1, wherein the metal polyphenol network chemically modified mica nanosheets have an absorbance higher than 1 in the ultraviolet band of 200-400 nm in the ultraviolet visible absorption spectrum, or have a transmittance lower than 50% in the ultraviolet transmittance spectrum of 200-400 nm. 6 . The UV-resistant elastomeric film of metal polyphenol network chemically modified mica nanosheets according to claim 1 , wherein the molar ratio between the plant polyphenols and the metal ions is in the range of 1:3-4:

1.

7. The anti-ultraviolet elastic film of mica nanosheets chemically modified by metal polyphenol network according to claim 1, wherein the plant polyphenols are selected from one or more of tannic acid and tea polyphenols.

8. The UV-resistant elastic film of metal polyphenol network chemically modified mica nanosheets according to claim 1, wherein the metal ions are selected from Cu 2+ , Fe 3+ Mg 2+ , Ca 2+ 、Zn 2+ and Mn 2+ One or more of .

9. The UV-resistant elastic film of metal polyphenol network chemically modified mica nanosheets according to claim 1, wherein: The mass ratio of the metal polyphenol network chemically modified mica nanosheets to the polyurethane is 1:9-1:

1.

10. A method for preparing an anti-ultraviolet elastic film of metal polyphenol network chemically modified mica nanosheets according to any one of claims 1 to 9, the method comprising the following steps: A) providing a suspension of exfoliated mica nanosheets in water; B) adding 10% to 50% of the mass of the mica nanosheets of plant polyphenols to the mica nanosheet suspension to obtain a mica nanosheet and plant polyphenol mixture; C) adding metal ions to the mixed solution, wherein the molar ratio between the plant polyphenols and the metal ions is between 1:3 and 4:1; D) adjusting the pH of the mixed solution of mica nanosheets, plant polyphenols and metal ions obtained in step C) to be weakly alkaline, so that the plant polyphenols and metal ions are complexed to obtain metal polyphenol network chemically modified mica nanosheets; E) mixing the metal polyphenol network chemically modified mica nanosheets obtained in step D) and polyurethane in a mass ratio of 1:9-1:1 to obtain a mixed solution; F) Assembling the mixed solution obtained in step E) by a solvent evaporation induced self-assembly method and drying it to obtain the anti-ultraviolet elastic film.

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