Spectral selective optical functional film, preparation method and outdoor blackening device

Abstract

The invention discloses a spectral selective optical functional film, a preparation method and an outdoor blackening device, and relates to the technical field of optical functional materials. The optical functional film comprises a flexible transparent base material and an ultraviolet light regulation and control functional area combined with the base material. And the ultraviolet light regulation and control functional area comprises a macromolecular medium and a spectrum selective active agent dispersed in the macromolecular medium. The functional film has specific spectral response characteristics: the average barrier rate is greater than or equal to 93% in a UVB wave band (280-315nm) easy to cause sunburn, and the average transmittance is greater than or equal to 88% in a UVA wave band (315-400nm) for promoting blackening. The invention also discloses a preparation process of the film and an outdoor blackening device, and the device utilizes the functional film as a shielding fabric to realize accurate light filtering. The technical problem that an existing outdoor product cannot achieve sunburn prevention and blackness promotion at the same time is effectively solved, health and blackness are achieved while skin safety is guaranteed, the visual field is clear, and weather resistance is high.

Description

Technical Field

[0001] This invention relates to the field of optical functional materials technology, and in particular to a spectrally selective optical functional film, its preparation method, and an outdoor tanning device. Background Technology

[0002] With the improvement of people's living standards and the diversification of aesthetic concepts, a healthy bronze or wheat-colored complexion (i.e., "tanning") has gradually become a fashion trend. Outdoor sunbathing is one of the main ways to achieve tanning. The ultraviolet rays in natural sunlight are mainly divided into UVA and UVB. Among them, the UVA band can reach the dermis and stimulate melanin production, which is the core band for achieving tanning; while the UVB band has stronger energy and mainly acts on the epidermis, which can easily lead to sunburn, redness, peeling, and even induce skin diseases.

[0003] Current outdoor tanning protective products mainly have the following problems: Ordinary sunscreens or sun-protective clothing often use broad-spectrum UV blocking technology, which blocks both UVA and UVB, thus failing to effectively tan.

[0004] Existing sun umbrella or tent fabrics either have extremely low light transmittance (complete blackout), making it impossible to enjoy sunbathing, or have high light transmittance but lack spectral selectivity, causing users to suffer excessive UVB damage while receiving UVA.

[0005] There is a lack of flexible thin film materials that can combine "precise light filtering" with "high visible light transmittance", and such materials need to have good weather resistance and mechanical strength to adapt to outdoor use environments.

[0006] Therefore, developing a spectrally selective optical functional film that can efficiently block UVB, highly transmit UVA and visible light, and applying it to outdoor devices is a technical problem that urgently needs to be solved. Summary of the Invention

[0007] The purpose of this invention is to provide a spectrally selective optical functional film with excellent spectral filtering capabilities, achieving healthy tanning while effectively preventing sunburn. Another purpose of this invention is to provide a method for preparing the aforementioned functional film and an outdoor tanning device incorporating the film.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: A spectrally selective optical functional film for healthy tanning, the optical functional film comprising a flexible transparent substrate and an ultraviolet light modulation functional region incorporated therein; The ultraviolet light modulation functional region comprises a polymer medium and a spectrally selective active agent dispersed therein; the optical functional film has the following optical properties: Average light blocking rate in the UVB band ≥90%; Average light transmittance in the UVA band ≥80%; The average light transmittance in the visible light band is ≥85%.

[0009] Preferably, the spectrally selective activator comprises at least one or a combination of cinnamic acid ester derivatives, benzimidazole derivatives, salicylate derivatives, triazine derivatives, or benzophenone derivatives.

[0010] Preferably, the spectrally selective activator is selected from the following components: isooctyl methoxycinnamate, phenylbenzimidazole sulfonic acid, octocrylene, ethylhexyl salicylate, or a compound of ethylhexyl methoxycinnamate and diethylaminohydroxybenzoylhexyl benzoate.

[0011] Preferably, the mass percentage of the spectrally selective active agent is 1.0% to 15.0% based on the total mass of the ultraviolet light-modulating functional region.

[0012] Preferably, the mass percentage of the spectrally selective surfactant is 3.5% to 4.5%. Preferably, the optical functional film is a multilayer composite structure, comprising: Substrate layer: composed of a transparent thermoplastic polymer, with a thickness of 0.04 mm to 0.50 mm; Functional coating: As the ultraviolet light modulation functional region, it is attached to at least one surface of the substrate layer and has a thickness of 0.01 mm to 0.20 mm; The functional coating is formed by curing an aqueous polyurethane resin, acrylic resin, or silicone resin containing the spectrally selective active agent.

[0013] Preferably, the material of the substrate layer is selected from one of ethylene-vinyl acetate copolymer (EVA), polyethylene terephthalate (PET), thermoplastic polyurethane (TPU) or polyvinyl chloride (PVC); the surface of the substrate layer is treated with corona discharge or primer, and the surface tension is ≥38 dynes.

[0014] Preferably, the optical functional film further includes an outermost weather-resistant protective layer, which is a transparent hydrophobic coating with a thickness of ≤0.1mm and a water contact angle of ≥90°.

[0015] The present invention also provides a method for preparing the above-mentioned spectrally selective optical functional film, comprising the following steps: (1) Dissolve or disperse the spectrally selective active agent, dispersant and leveling agent in a solvent to prepare a homogeneous functional additive premix; (2) The functional additive premix is ​​mixed with the polymer film-forming resin emulsion and homogenized at a shear rate of more than 1000 rpm to obtain the functional coating liquid. (3) The functional coating liquid is coated on the surface of a flexible transparent substrate and then subjected to graded thermal curing to form the ultraviolet light control functional area.

[0016] The present invention also provides an outdoor tanning device, including a support frame and a shading fabric mounted on the support frame, wherein the shading fabric is made of a spectrally selective optical functional film as described in any one of the above claims. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the cross-sectional structure of the spectrally selective optical functional film provided in an embodiment of the present invention.

[0019] Figure 2 This is a schematic diagram of the cross-sectional structure of an optical functional film with a weather-resistant protective layer provided in an embodiment of the present invention.

[0020] Figure 3 This is a comparison curve of the spectral transmittance of the embodiments and comparative examples of the present invention; wherein curve A represents the present invention, curve B represents a common transparent film, and curve C represents a common sunscreen product.

[0021] Figure 4 This is a graph showing the balance between the concentration of the spectrally selective surfactant, UVB blocking rate, and visible light transmittance in this invention; it demonstrates that 3.5%-4.5% is the optimal balance range.

[0022] Figure 5 This is a comparison chart of the UVB blocking rate retention rates of the present invention and the comparative example under QUV accelerated aging test.

[0023] 10 - Substrate layer; 20 - Functional coating; 30 - Weather-resistant protective layer. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0025] In the description of this invention, unless otherwise stated, "a plurality of" means two or more; the terms "center," "longitudinal," "lateral," "upper," "lower," "left," "right," "inner," "outer," "front end," "rear end," "head," "tail," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0026] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0027] I. Overall Technical Concept; This invention provides a spectrally selective optical functional film for healthy tanning, its preparation method, and an outdoor tanning device containing the film. The core design concept of this invention is to break through the limitation of traditional sunscreen products' "full-band blocking" and to construct a "fine sieve" for natural sunlight using spectral selectivity technology.

[0028] Unless otherwise specified, the terms used in this specification are defined as follows: "UVB band": refers to ultraviolet radiation with wavelengths ranging from 280nm to 315nm. This band has extremely high energy and is a major cause of skin erythema, sunburn, peeling, and DNA damage. One of the main objectives of this invention is to effectively shield this band.

[0029] "UVA band": refers to ultraviolet light with a wavelength range of 315nm to 400nm. This band has strong penetrating power, reaching directly to the dermis and stimulating melanocytes to produce melanin, making it the core band for achieving "tanning". This invention aims to preserve this band to the greatest extent possible.

[0030] "Visible light band": refers to the spectrum with wavelengths ranging from 400nm to 780nm, which determines the visual brightness and color perception of the human eye. This invention aims to maintain high transmittance to eliminate the visual oppressive feeling caused by traditional dark-colored sunscreen films.

[0031] II. Detailed structure of spectrally selective optical functional films; According to an embodiment of the present invention, the spectrally selective optical functional film is a multilayer composite structure, comprising, from the inside out, a flexible transparent substrate layer, an ultraviolet light modulation functional region (functional coating), and an optional weather-resistant protective layer.

[0032] 1. Flexible transparent substrate layer; The substrate layer is the physical carrier of the entire functional membrane, which determines the mechanical strength, flexibility and basic light transmittance of the membrane material.

[0033] Material selection: To meet the needs of portable outdoor storage (foldable and crease-free), thermoplastic polymer materials are preferred for the base layer.

[0034] EVA (ethylene-vinyl acetate copolymer): It has excellent flexibility and low-temperature resistance, does not easily turn white or break after folding, and has good transparency. EVA film with a vinyl acetate content (VA content) of 15%-30% is preferred.

[0035] PET (polyethylene terephthalate): It possesses excellent dimensional stability and tensile strength, making it suitable for applications requiring high flatness. BOPET film treated with a biaxial stretching process is preferred.

[0036] TPU (Thermoplastic Polyurethane): It has high elasticity, abrasion resistance and tear resistance, soft feel and good biocompatibility, making it suitable for close contact with human skin.

[0037] PVC (polyvinyl chloride): low cost, good weather resistance, and its hardness can be adjusted by adding plasticizers, making it suitable for large-scale industrial production.

[0038] Thickness parameters: The thickness range of the substrate layer is set to 0.04 mm to 0.50 mm.

[0039] When the thickness is less than 0.04mm, the membrane material is too thin and light, has poor wind resistance, and is prone to curling or deformation during the coating process.

[0040] When the thickness exceeds 0.50mm, the membrane material becomes too heavy and its rigidity increases, making it difficult to fold and store, and it also reduces the transmittance of visible light.

[0041] Preferred thickness: 0.10 mm to 0.20 mm. This thickness range achieves the best balance between mechanical strength and portability.

[0042] Surface treatment: Since some substrates (such as PET, PP, etc.) have low surface energy, the surface of the substrate must be modified in order to enhance the adhesion of the functional coating and prevent peeling.

[0043] Corona treatment: High-frequency high-voltage discharge generates polar groups (such as hydroxyl and carboxyl groups) on the surface of the substrate, thereby increasing the surface tension.

[0044] Primer treatment: Apply a very thin layer (0.1-1μm) of primer (such as polyurethane or acrylic primer) as a bridge for chemical bonding.

[0045] Specification requirements: The surface tension of the treated substrate should be ≥38 dynes (dyne / cm), preferably ≥42 dynes.

[0046] 2. Ultraviolet light modulation functional region; This is the core functional layer of the invention, which is essentially a "solid solution" or "dispersion" of a spectrally selective active agent encapsulated by a polymer resin.

[0047] Polymer media (film-forming resin): As a carrier for surfactants, it needs to have high transparency, good film-forming properties, and resistance to ultraviolet aging.

[0048] Waterborne polyurethane resin: environmentally friendly and non-toxic, with good flexibility and strong adhesion to EVA and TPU substrates. This invention preferably uses aliphatic waterborne polyurethane because it does not contain benzene rings and is less prone to yellowing.

[0049] Acrylic resin: extremely high transparency, low cost, and excellent weather resistance.

[0050] Organosilicon resins: They have excellent hydrophobicity and resistance to high and low temperatures, making them suitable for extreme environments.

[0051] Hybrid system: Polyurethane-acrylate copolymer emulsion (PUA) can also be used, which combines the advantages of both.

[0052] Spectroscopically selective surfactant (core ingredient): The selection of surfactants follows the principle of "narrow band absorption", that is, there is a strong absorption peak at 280-315nm, while the absorption decays rapidly at 315-400nm.

[0053] Cinnamic acid ester derivatives: such as isooctyl methoxycinnamate (OMC). OMC is a typical oil-soluble UVB absorber with a maximum absorption wavelength of around 310 nm. It has high UVB blocking efficiency and minimal impact on UVA transmission.

[0054] Benzimidazole derivatives: such as phenylbenzimidazole sulfonic acid (EHS). EHS is a water-soluble absorbent that can fill the hydrophilic regions in polymeric media, and can achieve full coverage when combined with oil-soluble components.

[0055] Other preferred components: Octocrylene: It has photostability and can protect other photodegradable surfactants.

[0056] Ethylhexyl salicylate: An auxiliary UVB absorber, often used as a solvent for other solid absorbers due to its good solubility.

[0057] The compound is a blend of ethylhexyl methoxycinnamate and hexyl diethylaminohydroxybenzoylbenzoate. Although the latter (DHHB) is primarily targeted at UVA, its addition in small amounts can adjust the steepness of the cutoff wavelength, resulting in a more perfect spectral profile.

[0058] Proportioning and concentration control: Wide range: Surfactants account for 1.0% to 15.0% of the total mass of the functional area.

[0059] Below 1.0%: There are insufficient active molecules per unit area, making it difficult to achieve a UVB blocking rate of over 90%.

[0060] Above 15.0%: Surfactants are prone to precipitation (blooming), causing the film surface to fog up, reducing visible light transmittance, and drastically increasing costs, and may even damage the film-forming properties of the resin (leading to cracking).

[0061] Preferred range: 3.5% to 4.5%. At this concentration, the inventors surprisingly discovered that while maintaining a UVB blocking rate of ≥93%, the UVA transmittance can be stably maintained at over 88%, achieving the "golden balance point".

[0062] Additive system: Dispersant: To prevent surfactant aggregation, a low-foaming dispersant needs to be added.

[0063] Leveling agents, such as polyether-modified siloxanes, ensure uniform surface tension during coating drying, eliminating pinholes and orange peel effects.

[0064] Limit: The total mass ratio of dispersant and leveling agent should be controlled at ≤1.5% to avoid introducing too many hydrophilic groups and reducing water resistance.

[0065] 3. Weather-resistant protective layer; It is located on the outermost side of the functional membrane (i.e., the side facing the sunlight).

[0066] Materials: Transparent hydrophobic coating, such as fluorocarbon resin, fluorinated acrylic resin or nano silica sol.

[0067] Characteristics: Water contact angle ≥90°, forming a "lotus effect".

[0068] Function: Prevents the functional layer from being eroded by sea salt spray and rainwater; it also has anti-fouling and self-cleaning functions, keeping the membrane surface clear for a long time.

[0069] Thickness: Extremely thin, ≤0.05mm (preferably 1-5μm), to avoid interference with optical performance.

[0070] III. Detailed Explanation of the Preparation Process; This invention provides a method for preparing the above-mentioned functional film using a wet coating process. This method particularly emphasizes "high-speed shear homogenization" and "gradual curing" to ensure the uniformity of the microstructure.

[0071] Step S1: Preparation of functional additive premix; Dissolve the selected ratio of a spectro-selective active agent (such as OMC or EHS) in a good solvent.

[0072] For oil-soluble surfactants (OMC), ethanol, isopropanol, or ethyl acetate can be used as co-solvents.

[0073] For water-soluble surfactants (EHS), the pH value must first be adjusted to 7.0-8.0 with a neutralizing agent (such as triethanolamine) to ensure complete dissolution in deionized water.

[0074] Add dispersant and leveling agent, and mix at low speed (300-500 rpm) for 10-20 minutes until a clear or translucent homogeneous solution is formed.

[0075] Step S2: Homogenization of the functional coating solution; The premixed liquid obtained in step S1 is slowly added dropwise to the polymer film-forming resin emulsion (such as an aqueous polyurethane emulsion).

[0076] Key process: Turn on the high-speed disperser or homogenizer and set the shear rate to above 1000 rpm (preferably 1500-3000 rpm).

[0077] Principle: High shear force breaks down surfactant droplets into nanometer or submicron sizes (particle size <500nm), allowing them to be encapsulated by resin micelles. This not only improves the coating's transparency (reducing Rayleigh scattering) but also ensures comprehensive UVB absorption coverage.

[0078] Homogenization time: 15-30 minutes, followed by standing to defoam or vacuum defoaming.

[0079] Step S3: Precision coating and graded thermosetting; Coating method: The substrate layer is spread out and coated using a gravure coater, slot extrusion coater, or comma blade coater. For laboratory preparation, a wire bar coater can be used.

[0080] Wet film thickness control: The wet film thickness is calculated based on the solid content and the target dry film thickness, and is usually between 20-150 μm.

[0081] Graded thermosetting: To avoid surface skin formation leading to internal solvent residue (bubbling), a three-stage oven drying process is used. Low temperature zone (50-60℃): Mainly volatilizes low-boiling-point solvents and surface moisture, leveling stage.

[0082] Medium temperature zone (70-90℃): Main drying stage, resin particles begin to fuse.

[0083] High-temperature zone (100-120℃): Complete cross-linking and curing stage, forming a dense coating.

[0084] Note: For heat-sensitive substrates (such as EVA), the temperature in the high-temperature zone should not exceed its softening point (approximately 70-80℃), and the drying time should be extended accordingly or a low-temperature, long-term curing method should be used.

[0085] IV. Mechanical structure of outdoor tanning equipment; The outdoor tanning device in this embodiment combines the aforementioned functional film with a sophisticated mechanical support system, achieving a balance between "portable storage" and "stable support".

[0086] 1. Overall architecture; The device consists of three main parts: a foldable support mechanism, a UVB-specific filter membrane (masking fabric), and a rotary locking assembly.

[0087] 2. Seat and storage design; The base is cylindrical or polygonal and serves as the central hub of the entire device.

[0088] Storage grooves: Several (e.g., 3-8) longitudinal grooves are evenly distributed along the circumference on the outer wall of the base. The depth and width of the grooves match the size of the support rod, so that the support rod can be completely embedded in the groove after folding, resulting in a smooth overall appearance without any protruding edges.

[0089] 3. Foldable support rod; Segmented structure: Each support pole consists of at least two (preferably 3-4) sub-pole sections. The sub-pole sections are connected by elastic ropes (similar to tent poles) or by eccentric locks / ball locks to achieve telescopic adjustment.

[0090] Material: 7075 aerospace aluminum alloy or carbon fiber tube is preferred, which balances lightweight (total weight ≤1.5kg) and high strength.

[0091] Anti-slip design: The end of the support rod is equipped with an anti-slip sleeve made of rubber or silicone, and the bottom is designed with anti-slip texture to increase the friction with the beach, grass or ground and prevent it from being blown away by the wind.

[0092] 4. Rotary locking assembly; Structure: Includes a rotating seat rotatably connected to the bottom of the base, and a limiting head fixed to the top of the rotating seat.

[0093] Limiting head structure: It is petal-shaped or gear-shaped, with alternating limiting protrusions and through grooves (notches).

[0094] Working principle: Expanded / Retracted State: Rotate the rotating base so that the "pass groove" of the limiting head aligns with the "retractable groove" on the base. At this time, the base of the support rod is unobstructed and can freely rotate out (expand) or in (retract) from the retractable groove.

[0095] Locked state: After the support rod is fully extended, rotate the rotating seat by an angle (e.g., 45 degrees) to make the "limiting protrusion" of the limiting head rotate to the bottom or side of the storage slot, physically abutting the root structure of the support rod, preventing it from rotating and folding, thus achieving locking.

[0096] Operational advantages: All support rods can be locked synchronously with a single hand rotation, greatly enhancing the user experience.

[0097] 5. Connection between membrane and frame; Detachable design: The edges of the UVB-specific filter membrane are sewn with reinforcing webbing and several fasteners (such as D-rings and elastic cord buckles). The support rod ends are equipped with corresponding hooks or slots.

[0098] This design allows users to remove the membrane for individual cleaning or replacement when not in use, and also facilitates the replacement of membranes with different filter parameters in different weather conditions (for example, a set of devices is equipped with two types of membranes: "powerful tanning" and "mild tanning").

[0099] V. Experimental Examples and Performance Verification; To verify the technical effects of the present invention, we prepared several embodiments and conducted rigorous optical tests.

[0100] Testing standards and equipment: UV transmittance tester: Labsphere UV-2000S UV transmittance analyzer was used.

[0101] Contact angle tester: KrussDSA100.

[0102] Test bands: UVB (280-315nm), UVA (315-400nm), Visible (400-780nm).

[0103] Example 1: EVA substrate + oil-soluble OMC; Formula: 0.12mm thick EVA film + 4.0% OMC + 0.6% dispersant + waterborne polyurethane.

[0104] Preparation: Shear rate 1500 rpm, dry film thickness of coating 0.03 mm.

[0105] Test data: Average UVB blocking rate: 94.5%; Average UVA transmittance: 89.2%; Visible light transmittance: 91.0%; Evaluation: Fully meets the requirements for healthy tanning, provides significant sun protection, and offers clear vision.

[0106] Example 2: PET substrate + water-soluble EHS; Formula: 0.10mm thick PET film + 12.0% EHS + water-based acrylic resin.

[0107] Preparation: EHS was first neutralized and dissolved with triethanolamine at a shear rate of 1200 rpm.

[0108] Test data: Average UVB blocking rate: 97.0% (the high concentration of EHS provides extremely high UVB shielding). Average UVA transmittance: 82.0% (slightly lower than Example 1, but still acceptable); Visible light transmittance: 87.0%; Evaluation: Suitable for users with extremely high requirements for sun protection (such as those with sensitive skin), the PET substrate provides a smoother appearance.

[0109] Example 3: TPU substrate + compounded surfactant + hydrophobic coating; Formula: 0.20mm TPU film + 3.5% (OMC + DHHB compound) + fluorine-modified polyurethane coating.

[0110] Preparation: Double-layer coating process, with an outer layer of 0.005mm hydrophobic layer.

[0111] Test data: Average UVB blocking rate: 93.2%; Average UVA transmittance: 88.5%; Visible light transmittance: 90.5%; Water contact angle: 105°; Evaluation: It has excellent self-cleaning function, and water droplets quickly roll off the membrane surface, making it suitable for environments with splashing waves at the beach.

[0112] Example 4: Extremely low concentration control (1.0% OMC); Formula: Except that the OMC concentration is reduced to 1.0%, the rest is the same as in Example 1.

[0113] Test data: Average UVB blocking rate: 82.5%; Conclusion: The barrier effect did not reach the optimal target of 90%, indicating that the surfactant concentration was too low to provide sufficient protection and posed a risk of sunburn. However, it is still superior to ordinary transparent plastic film.

[0114] Example 5: Extremely high concentration control (18.0% OMC); Formula: OMC concentration increased to 18.0%.

[0115] Phenomenon: After the film dries, white powder appears (blooming), and it feels sticky to the touch.

[0116] Test data: Average UVB blocking rate: 99.0%; Visible light transmittance: 75.0% (due to increased haze caused by precipitates); Conclusion: Although the sun protection effect is good, it seriously affects the visual experience and the physical properties of the film, proving that the upper limit of 15.0% is reasonable.

[0117] Comparative Example 1: Ordinary sunscreen film (broad-spectrum absorption); Use commercially available ordinary sun protection car film (with added broad-spectrum nano titanium dioxide).

[0118] Test data: UVB blocking rate 98%, UVA transmittance only 15%.

[0119] Conclusion: It is completely impossible to achieve a tanning effect.

[0120] Comparative Example 2: Transparent film without absorbent; Pure EVA film, containing no surfactants.

[0121] Test data: UVB transmittance 70%.

[0122] Conclusion: Users experienced skin redness and swelling (sunburn) after 30 minutes of outdoor exposure using the membrane, proving that the filter coating of this invention is the core key.

[0123] VI. Data Analysis and Performance Verification; To further verify the technical effects of the present invention, we conducted systematic optical and weather resistance tests on the embodiments and comparative examples. The test results are as follows: Figures 3 to 5 As shown.

[0124] 1. Spectroscopic selectivity analysis (combined with...) Figure 3 )like Figure 3 As shown, the horizontal axis represents wavelength (nm) and the vertical axis represents transmittance (%).

[0125] Curve B (Comparative Example 1 - Ordinary Transparent Film): As shown in the figure, Curve B presents as a nearly straight line of high transmittance. Within the entire test wavelength range of 200nm to 800nm, its transmittance remains consistently high at around 95%. This indicates that the ordinary transparent substrate without added spectrally selective surfactants has almost no ability to filter light; not only is visible light completely transparent, but harmful UVB ultraviolet rays can also penetrate without hindrance (with a transmittance also as high as around 95%), directly irradiating human skin and posing an extremely high risk of sunburn.

[0126] Curve A (in this invention): In stark contrast to the flatness of curve B, curve A exhibits a specific spectral response.

[0127] In the visible light region (>400nm): Curve A maintains a high transmittance (approximately 88%), only slightly lower than curve B. This indicates that the addition of the surfactant in this invention has minimal impact on the transparency of the field of view, and users can still obtain a clear and bright visual experience during use.

[0128] In the UVB band (280-315nm): Curve A shows a precipitous drop, with transmittance rapidly reduced from 88% in the visible light region to below 5%.

[0129] Curve C (Comparative Example 2 - Ordinary Sunscreen Product): It exhibits low transmittance across the entire spectrum (<5%). Although it blocks UVB, it also completely loses the UVA and visible light needed for tanning.

[0130] In summary, by comparing curve A with the "flat and high-transparency" curve B, it can be clearly seen that this invention, without sacrificing transparency (the two curves in the visible light region are very close in height), has created a safe protection zone in the UVB band through chemical means, perfectly achieving the spectral screening effect of "removing falsehoods and retaining truth".

[0131] 2. Critical range analysis of surfactant concentration (combined with...) Figure 4 )like Figure 4 As shown, this mainly demonstrates the effect of the content of spectrally selective surfactants on membrane performance.

[0132] The solid red line (UVB blocking rate) shows that the blocking rate increases significantly with increasing surfactant concentration. When the concentration reaches approximately 3.5%, the blocking rate exceeds 93% and then plateaus; further increases in concentration contribute less to the improvement in blocking rate.

[0133] Blue dashed line (visible light transmittance): As the concentration increases, the transmittance shows a slow decreasing trend. When the concentration exceeds 15.0%, the haze increases sharply due to the precipitation or aggregation of the surfactant in the substrate, and the visible light transmittance drops precipitously.

[0134] Therefore, the 3.5%-4.5% range (green area) shown in the figure is the optimal implementation range of the present invention. Within this range, the product has both excellent protective performance and excellent optical transparency.

[0135] 3. Weather resistance test analysis (combined with) Figure 5 )like Figure 5 As shown, the performance changes of the embodiments and comparative examples of the present invention in the QUV accelerated aging test chamber are illustrated (test conditions: UVB-313 lamp, irradiance 0.71W / m²).

[0136] Solid green line (this invention): Thanks to the protection of the weather-resistant protective layer and the optimized dispersion process, after 200 hours of aging, the UVB blocking rate of this invention is still maintained at over 97.5%, with no significant attenuation.

[0137] Gray dashed line (comparative example): The film prepared using ordinary processes begins to show a significant decline in performance after 50 hours of aging, indicating that the surfactant has decomposed or migrated.

[0138] Through the detailed description of the embodiments above, those skilled in the art can clearly understand the technical solution, manufacturing process, and working principle of the present invention, and can reproduce products with corresponding technical effects accordingly. The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any equivalent transformations based on the technical concept of the present invention (such as using other chemical substances with similar spectral characteristics, or making simple shape changes to the mechanical structure) should fall within the scope of protection of the present invention.

[0139] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A spectrally selective optical functional film, characterized in that, The optical functional film includes a flexible transparent substrate and an ultraviolet light modulation functional region bonded to the substrate; The ultraviolet light modulation functional region comprises a polymer medium and a spectrally selective active agent dispersed therein; the optical functional film has the following optical properties: Average light blocking rate in the UVB band ≥90%; Average light transmittance in the UVA band ≥80%.

2. The spectrally selective optical functional film as described in claim 1, characterized in that, The spectrally selective activator comprises at least one or a combination of cinnamic acid ester derivatives, benzimidazole derivatives, salicylate derivatives, triazine derivatives, or benzophenone derivatives.

3. The spectrally selective optical functional film according to any one of claims 1-2, characterized in that, The mass percentage of the spectrally selective active agent is 1.0% to 15.0% based on the total mass of the ultraviolet light-modulating functional region.

4. The spectrally selective optical functional film as described in claim 1, characterized in that, The optical functional film is a multilayer composite structure, comprising: Substrate layer: composed of a transparent thermoplastic polymer, with a thickness of 0.04 mm to 0.50 mm; Functional coating: As the ultraviolet light modulation functional region, it is attached to at least one surface of the substrate layer and has a thickness of 0.01 mm to 0.20 mm.

5. The spectrally selective optical functional film as described in claim 4, characterized in that, The material of the substrate layer is selected from one of ethylene-vinyl acetate copolymer, polyethylene terephthalate, thermoplastic polyurethane, or polyvinyl chloride; the surface of the substrate layer is treated with corona discharge or primer, and the surface tension is ≥38 dynes.

6. The spectrally selective optical functional film as described in claim 1, characterized in that, The optical functional film also includes an outermost weather-resistant protective layer, which is a transparent hydrophobic coating with a thickness of ≤0.1mm and a water contact angle of ≥90°.

7. A method for preparing a spectrally selective optical functional film as described in any one of claims 1-6, characterized in that, Includes the following steps: (1) Dissolve or disperse the spectrally selective active agent, dispersant and leveling agent in a solvent to prepare a homogeneous functional additive premix; (2) The functional additive premix is ​​mixed with the polymer film-forming resin emulsion and homogenized at a shear rate of more than 1000 rpm to obtain the functional coating liquid. (3) The functional coating liquid is coated on the surface of a flexible transparent substrate and then subjected to graded thermal curing to form the ultraviolet light control functional area.

8. An outdoor tanning device, characterized in that, It includes a support frame and a shielding fabric mounted on the support frame, the shielding fabric being made of a spectrally selective optical functional film as described in any one of claims 1-6.

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