Intelligent umbrella with transparent photosensitive color-changing layer and preparation method of intelligent umbrella

Abstract

The invention relates to the technical field of intelligent umbrellas, and discloses an intelligent umbrella with a transparent photosensitive color-changing layer, the intelligent umbrella comprises an umbrella cover, umbrella ribs, an umbrella handle and a control system, the umbrella cover is of a five-layer composite structure, and the five-layer composite structure sequentially comprises a hydrophobic protection layer, the transparent photosensitive color-changing layer, an ultraviolet absorption layer, a structure enhancement layer and a waterproof glue layer from outside to inside. According to the intelligent umbrella containing the transparent photosensitive color-changing layer and the preparation method of the intelligent umbrella, the problem that a color-changing threshold value is fixed is solved through the synergistic effect of the transparent photosensitive color-changing layer and the ultraviolet absorption layer: spiropyrane and naphthopyran synergistic color-changing molecules of the transparent photosensitive color-changing layer react only under the irradiation of 280-400 nm ultraviolet rays; spiropyrane is subjected to ring opening to generate a merocyanine structure, so that the umbrella surface is turned into a dark amber color, and naphthopyran expands the color changing range; titanium dioxide-zinc oxide composite nanoparticles of the ultraviolet absorption layer precisely limit a trigger wave band, so that visible light interference is avoided, and the pertinence and reliability of color change response are improved.

Description

Technical Field

[0001] This invention relates to the field of smart umbrella technology, specifically to a smart umbrella containing a transparent photosensitive color-changing layer and its preparation method. Background Technology

[0002] Traditional umbrellas, as basic rain gear for daily travel, have long been limited to the single function of providing rain or sun protection. They cannot adaptively adjust the light transmittance and color of the umbrella surface according to the dynamic changes in the intensity of external light, which leads to a series of drawbacks in actual use.

[0003] In direct sunlight, traditional umbrellas have limited ability to block ultraviolet rays, with generally high UV transmittance. This makes them ineffective at blocking harmful UV rays in the 280-400nm wavelength range, leading to excessive exposure of the user's skin to UV radiation and increasing the risk of sunburn and premature aging. Their sun protection performance is clearly insufficient. On cloudy or rainy days or in low-light conditions, the fixed color of traditional umbrellas, coupled with already low visibility, makes it difficult for pedestrians to be clearly identified by passing vehicles, increasing the risk of traffic accidents and posing a significant safety hazard. Furthermore, traditional umbrellas often use a single, fixed color, lacking dynamic visual effects that change with the environment, making it difficult to meet the demands of younger consumers for personalized and fashionable products, thus limiting their market adaptability.

[0004] To address some of the aforementioned issues, existing technologies have attempted to coat umbrella surfaces with ordinary photochromic inks. However, these solutions still suffer from several insurmountable drawbacks: First, ordinary photochromic inks have a fixed color-changing threshold, making precise control over specific ultraviolet wavelengths impossible. They are susceptible to interference from other wavelengths of light, such as visible light, leading to false color changes and insufficient targeting and reliability of the color-changing response. Second, these ink coatings are often opaque or semi-transparent, significantly reducing the visual transparency of the umbrella surface. This is especially problematic in low-light conditions, such as cloudy or rainy days, as it can impair the user's vision and exacerbate safety hazards. Third, ordinary photochromic inks have poor weather resistance. After prolonged exposure to sunlight, rain, and temperature changes, their color-changing molecules are prone to degradation or structural damage, resulting in slower color-changing speeds, decreased color depth, or even complete loss of color-changing performance. This makes it difficult to meet the long-term needs of umbrellas. Therefore, a smart umbrella with a transparent photosensitive color-changing layer and its preparation method have been proposed. Summary of the Invention

[0005] (a) Technical problems to be solved

[0006] To address the shortcomings of existing technologies, this invention provides a smart umbrella with a transparent photosensitive color-changing layer and its preparation method. It features the use of a transparent photosensitive color-changing polymer to achieve rapid and reversible color changing under high light transmittance; the introduction of a nano-level titanium dioxide-zinc oxide composite ultraviolet absorber to precisely limit the color-changing triggering band to 280–400 nm, avoiding false triggering by visible light; and the use of a three-layer co-extrusion casting process to integrate the TSP layer with the polyurethane waterproof layer and the polycarbonate support layer, improving weather resistance. These advantages solve the problems of existing umbrellas, such as a fixed color-changing threshold, inability to precisely control the color according to the ultraviolet band, opaque layers affecting visual transparency, and color-changing performance degradation and poor weather resistance after long-term use.

[0007] (II) Technical Solution

[0008] To achieve the aforementioned use of a transparent photosensitive color-changing polymer for rapid and reversible color change under high light transmittance, and to introduce a nano-level titanium dioxide-zinc oxide composite ultraviolet absorber to precisely limit the color-changing triggering band to 280–400nm, thus avoiding false triggering by visible light, and to improve weather resistance by employing a three-layer co-extrusion casting process to integrate the TSP layer with the polyurethane waterproof layer and the polycarbonate support layer, the present invention provides the following technical solution: a smart umbrella containing a transparent photosensitive color-changing layer, comprising an umbrella canopy, umbrella ribs, an umbrella handle, and a control system. The umbrella canopy has a five-layer composite structure, consisting of, from the outside to the inside, a hydrophobic protective layer, a transparent photosensitive color-changing layer, an ultraviolet absorption layer, a structural reinforcement layer, and a waterproof adhesive layer.

[0009] The hydrophobic protective layer is fluorosilane-modified polytetrafluoroethylene with a thickness of 2 μm; the transparent photosensitive color-changing layer is composed of spiropyran and naphthopyran synergistic color-changing molecules; the ultraviolet absorption layer contains titanium dioxide-zinc oxide composite ultraviolet absorber nanoparticles dispersed in the EVA matrix; the structural reinforcement layer is a transparent polycarbonate film with a thickness of 100 μm; and the waterproof adhesive layer is a polyurethane hot melt adhesive with a thickness of 20 μm.

[0010] Preferably, the total thickness of the umbrella surface is 200–250 μm.

[0011] Preferably, under 280-400nm ultraviolet irradiation, the spiropyran molecules of the transparent photosensitive color-changing layer undergo a ring-opening reaction to generate a cyanine structure. The absorption peak of the cyanine structure is 550nm, and the umbrella surface changes from colorless and transparent to deep amber. After the ultraviolet light disappears, the cyanine structure closes its ring and returns to colorless, with a color-changing time of ≤1s. Naphthopyran molecules can extend the color-changing range to 450-600nm, achieving dynamic blue-purple changes.

[0012] Preferably, the umbrella rib is a carbon fiber hollow tube with a flexible copper wire embedded inside. The diameter of the flexible copper wire is 0.1 mm. One end of the flexible copper wire is connected to a micro photovoltaic cell at the umbrella handle, and the other end is connected to an LED warning light at the end of the umbrella rib. The micro photovoltaic cell has a size of 2 cm × 1 cm and an operating voltage of 3.7 V ± 0.2 V.

[0013] Preferably, the control system includes a light intensity sensor and a switch module. The light intensity sensor is disposed on the surface of the umbrella handle. When the light intensity sensor detects a light intensity of <100 lux, the switch module is automatically turned on, and the LED warning light is activated. The power of the LED warning light is 0.5W.

[0014] A method for manufacturing a smart umbrella containing a transparent photosensitive color-changing layer, comprising the smart umbrella containing a transparent photosensitive color-changing layer, and the following steps:

[0015] S1: Preparation of a transparent photosensitive color-changing layer

[0016] Spiropyran and naphthopyran were dissolved in methyl methacrylate, with spiropyran accounting for 0.5% by mass and naphthopyran accounting for 0.3% by mass. Irgacure 184 photoinitiator was added, with a mass percentage of 0.2%. After thorough mixing, a 50 μm thick transparent film was formed by UV curing. The UV curing parameters were: wavelength 365 nm and power 500 mW / cm². 2 Time: 30 seconds;

[0017] S2: Preparation of the ultraviolet absorption layer

[0018] Titanium dioxide-zinc oxide composite UV absorber nanoparticles were added to an EVA toluene solution, with the mass percentage of the titanium dioxide-zinc oxide composite UV absorber nanoparticles being 5% and the solid content of the EVA toluene solution being 15%. The nanoparticles were dispersed by ultrasonic dispersion at a power of 300W for 30 minutes. The nanoparticles were then coated onto the surface of the structural reinforcement layer using a slot coater and dried at 80°C for 30 minutes to form a 30μm thick coating.

[0019] S3: Co-extrusion composite

[0020] A three-layer co-extrusion casting machine is used to simultaneously extrude the transparent photosensitive color-changing layer, the ultraviolet absorption layer, and the structural reinforcement layer. The die temperature is 220℃, and the material is shaped by a 20℃ cooling roller. Subsequently, the hydrophobic protective layer and the waterproof adhesive layer are respectively bonded to both sides by hot pressing. The hot pressing parameters are 60℃ temperature and 0.3MPa pressure to form a complete umbrella surface.

[0021] S4: Molding and Assembly

[0022] The composite umbrella surface is hot-pressed and cut into a fan shape at 180℃ and 0.5MPa, and then spliced ​​into a circular umbrella surface by high-frequency welding. The flexible copper wire of the umbrella rib is connected to the micro photovoltaic cell and LED warning light of the umbrella handle, and the control system is assembled to complete the overall assembly.

[0023] Preferably, in step S3, the extrusion speed of the three-layer co-extrusion casting machine is 1.2 m / min, and the rotation speed of the cooling roller is matched with the extrusion speed; during hot pressing, the bonding surface of the hydrophobic protective layer and the transparent photosensitive color-changing layer is treated with plasma, and the parameters of the plasma treatment are power 500W and time 10s, and the interface bonding strength after treatment is ≥2N / cm.

[0024] Preferably, in step S4, the parameters for high-frequency welding are: frequency 35kHz, pressure 0.2MPa, welding time 1.5s, weld width ≤0.5mm; and the water pressure resistance of the umbrella surface 1 after welding ≥50kPa.

[0025] (III) Beneficial Effects

[0026] Compared with the prior art, the present invention provides a smart umbrella containing a transparent photosensitive color-changing layer and a method for preparing the same, which has the following beneficial effects:

[0027] 1. The smart umbrella containing a transparent photosensitive color-changing layer and its preparation method solve the problem of fixed color-changing threshold through the synergistic effect of the transparent photosensitive color-changing layer and the ultraviolet absorption layer: the spiropyran and naphthopyran synergistic color-changing molecules in the transparent photosensitive color-changing layer react only under 280-400nm ultraviolet irradiation. The anthocyanin structure generated by the ring opening of spiropyran causes the umbrella surface to turn into a deep amber color, while naphthopyran expands the color-changing range; the titanium dioxide-zinc oxide composite nanoparticles in the ultraviolet absorption layer precisely limit the triggering band, avoid visible light interference, and improve the specificity and reliability of the color-changing response.

[0028] 2. The smart umbrella with a transparent photosensitive color-changing layer and its manufacturing method. The five-layer composite structure of the umbrella surface solves the problem of visual transparency: the transparent photosensitive color-changing layer is a UV-cured transparent film, and the structural reinforcement layer is a polycarbonate transparent film. Both ensure an initial light transmittance of 87%. Even after ultraviolet irradiation, the color-changing layer still maintains a certain degree of light transmittance, and does not affect vision in low-light scenarios such as cloudy or rainy days, overcoming the safety hazards caused by the opacity of ordinary ink coatings.

[0029] 3. The smart umbrella containing a transparent photosensitive color-changing layer and its preparation method improve weather resistance through a three-layer co-extrusion casting and hot-pressing composite process: the three-layer co-extrusion casting machine integrates the transparent photosensitive color-changing layer, the ultraviolet absorption layer, and the structural reinforcement layer into a single molding process; during hot-pressing composite, the hydrophobic protective layer and the transparent photosensitive color-changing layer are treated with plasma, and the interface bonding strength is ≥2N / cm; the hydrophobic protective layer is water-resistant, the waterproof adhesive layer is sealed, and the color-changing efficiency retention rate is ≥90% after 2000h aging, meeting the requirements for long-term use. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the overall structure of the smart umbrella of the present invention;

[0031] Figure 2 This is a schematic diagram of the five-layer structure of the umbrella canopy of the present invention;

[0032] Figure 3 This is a diagram of the control system architecture of the present invention;

[0033] Figure 4 This is a flowchart of the preparation method of the smart umbrella of the present invention.

[0034] In the diagram: 1. Umbrella canopy; 101. Hydrophobic protective layer; 102. Transparent photochromic layer; 103. Ultraviolet absorption layer; 104. Structural reinforcement layer; 105. Waterproof adhesive layer; 2. Umbrella ribs; 3. Umbrella handle; 4. Control system. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] Please see Figure 1-4 A smart umbrella with a transparent photosensitive color-changing layer includes an umbrella surface 1, umbrella ribs 2, umbrella handle 3 and control system 4. The umbrella surface 1 has a five-layer composite structure, which consists of a hydrophobic protective layer 101, a transparent photosensitive color-changing layer 102, an ultraviolet absorption layer 103, a structural reinforcement layer 104 and a waterproof adhesive layer 105, from the outside to the inside.

[0037] The hydrophobic protective layer 101 is fluorosilane-modified polytetrafluoroethylene with a thickness of 2 μm; the transparent photosensitive color-changing layer 102 is composed of spiropyran and naphthopyran synergistic color-changing molecules; the ultraviolet absorption layer 103 contains titanium dioxide-zinc oxide composite ultraviolet absorber nanoparticles dispersed in the EVA matrix; the structural reinforcement layer 104 is a transparent polycarbonate film with a thickness of 100 μm; and the waterproof adhesive layer 105 is a polyurethane hot melt adhesive with a thickness of 20 μm.

[0038] A method for manufacturing a smart umbrella containing a transparent photosensitive color-changing layer, comprising the smart umbrella containing a transparent photosensitive color-changing layer, and the following steps:

[0039] S1: Preparation of a transparent photosensitive color-changing layer

[0040] Spiropyran and naphthopyran were dissolved in methyl methacrylate, with spiropyran accounting for 0.5% by mass and naphthopyran accounting for 0.3% by mass. Irgacure 184 photoinitiator was added, with a mass percentage of 0.2%. After thorough mixing, a 50 μm thick transparent film was formed by UV curing. The UV curing parameters were: wavelength 365 nm and power 500 mW / cm². 2 Time: 30 seconds;

[0041] S2: Preparation of the ultraviolet absorption layer

[0042] Titanium dioxide-zinc oxide composite UV absorber nanoparticles were added to an EVA toluene solution, with the mass percentage of the titanium dioxide-zinc oxide composite UV absorber nanoparticles being 5% and the solid content of the EVA toluene solution being 15%. The nanoparticles were dispersed by ultrasonic dispersion at a power of 300W for 30 minutes. The nanoparticles were then coated onto the surface of the structural reinforcement layer using a slot coater and dried at 80°C for 30 minutes to form a 30μm thick coating.

[0043] S3: Co-extrusion composite

[0044] A three-layer co-extrusion casting machine is used to simultaneously extrude the transparent photosensitive color-changing layer 102, the ultraviolet absorption layer 103, and the structural reinforcement layer 104. The die temperature is 220℃, and the layers are shaped by a 20℃ cooling roller. Subsequently, the hydrophobic protective layer 101 and the waterproof adhesive layer 105 are respectively bonded to both sides by hot pressing. The hot pressing parameters are 60℃ temperature and 0.3MPa pressure to form a complete umbrella surface 1.

[0045] S4: Molding and Assembly

[0046] The composite umbrella surface 1 is hot-pressed and cut into a fan shape at 180℃ and 0.5MPa, and then spliced ​​into a circular umbrella surface by high-frequency welding; the flexible copper wire of the umbrella rib 2 is connected to the micro photovoltaic cell and LED warning light of the umbrella handle 3, and the control system 4 is assembled to complete the overall assembly.

[0047] Example 1:

[0048] This embodiment provides a smart umbrella with a transparent photosensitive color-changing layer, including an umbrella canopy 1, umbrella ribs 2, umbrella handle 3, and a control system 4.

[0049] The umbrella surface 1 has a five-layer composite structure, consisting of a hydrophobic protective layer 101, a transparent photosensitive color-changing layer 102, an ultraviolet absorption layer 103, a structural reinforcement layer 104, and a waterproof adhesive layer 105, from the outside to the inside.

[0050] The hydrophobic protective layer 101 is fluorosilane-modified polytetrafluoroethylene with a thickness of 2 μm; the transparent photosensitive color-changing layer 102 is composed of spiropyran and naphthopyran synergistic color-changing molecules, with spiropyran accounting for 0.5% by mass and naphthopyran accounting for 0.3% by mass, dispersed in a methyl methacrylate matrix, and has a thickness of 50 μm after UV curing; under 280-400 nm ultraviolet irradiation, the spiropyran molecules undergo a ring-opening reaction to generate a cyanine structure, the absorption peak of which is 550 nm, and the umbrella surface 1 changes from colorless and transparent to deep amber; after the ultraviolet light disappears, the cyanine structure closes its ring and returns to colorless, with a color-changing time ≤1 s; the naphthopyran molecules can extend the color-changing range to 450-600 nm, achieving a dynamic change from blue to purple.

[0051] The ultraviolet absorption layer 103 contains titanium dioxide-zinc oxide composite ultraviolet absorber nanoparticles dispersed in the EVA matrix, with the nanoparticles accounting for 5% of the mass and a thickness of 30μm; the structural reinforcement layer 104 is a transparent polycarbonate film with a thickness of 100μm; and the waterproof adhesive layer 105 is a polyurethane hot melt adhesive with a thickness of 20μm.

[0052] The total thickness of the umbrella canopy 1 is 200-250μm; the umbrella rib 2 is a hollow carbon fiber tube with a flexible copper wire embedded inside, the flexible copper wire having a diameter of 0.1mm; one end of the flexible copper wire is connected to a micro photovoltaic cell at the umbrella handle 3, and the other end is connected to an LED warning light at the end of the umbrella rib 2; the micro photovoltaic cell has a size of 2cm×1cm and an operating voltage of 3.7V±0.2V; the LED warning light has a power of 0.5W.

[0053] The control system 4 includes a light intensity sensor and a switch module. The light intensity sensor is set on the surface of the umbrella handle 3. When the light intensity sensor detects a light intensity of <100 lux, the switch module is automatically turned on, and the LED warning light is activated.

[0054] Example 2:

[0055] This embodiment provides a method for preparing a smart umbrella containing a transparent photosensitive color-changing layer, used to prepare the smart umbrella of Embodiment 1. The specific steps are as follows:

[0056] S1: Preparation of transparent photosensitive color-changing layer 102

[0057] Weigh out 0.5% spiropyran and 0.3% naphthylpyran by mass ratio, and dissolve them in methyl methacrylate; add photoinitiator Irgacure 184 at a mass ratio of 0.2%; stir evenly and then cure by UV to form a 50μm thick transparent film. The UV curing parameters are wavelength 365nm and power 500mW / cm². 2 Time: 30 seconds.

[0058] S2: Preparation of UV absorption layer 103

[0059] Titanium dioxide-zinc oxide composite UV absorber nanoparticles were added to an EVA toluene solution, with the titanium dioxide-zinc oxide composite UV absorber nanoparticles accounting for 5% by mass and the solid content of the EVA toluene solution being 15%. The nanoparticles were dispersed by ultrasonic dispersion at a power of 300W for 30 minutes. The nanoparticles were then coated onto the surface of the structural reinforcement layer 104 using a slot coater and dried at 80°C for 30 minutes to form a 30μm thick coating.

[0060] S3: Co-extrusion composite

[0061] A three-layer co-extrusion casting machine is used to simultaneously extrude the transparent photosensitive color-changing layer 102, the ultraviolet absorption layer 103, and the structural reinforcement layer 104. The die temperature is 220℃, and the layers are shaped by a 20℃ cooling roller. Subsequently, the hydrophobic protective layer 101 and the waterproof adhesive layer 105 are respectively bonded to both sides by hot pressing. The hot pressing parameters are 60℃ temperature and 0.3MPa pressure. The bonding surface between the hydrophobic protective layer 101 and the transparent photosensitive color-changing layer 102 is treated with plasma. The plasma treatment parameters are 500W power and 10s time. After treatment, the interface bonding strength is ≥2N / cm, forming a complete umbrella surface 1.

[0062] S4: Molding and Assembly

[0063] The composite umbrella surface 1 is hot-pressed and cut into a fan shape at 180℃ and 0.5MPa; it is then spliced ​​into a circular umbrella surface by high-frequency welding. The parameters for high-frequency welding are frequency 35kHz, pressure 0.2MPa, welding time 1.5s, and weld width ≤0.5mm. After welding, the water pressure resistance of the umbrella surface 1 is ≥50kPa. The flexible copper wire of the umbrella rib 2 is connected to the micro photovoltaic cell and LED warning light of the umbrella handle 3, and the control system 4 is assembled to complete the overall assembly.

[0064] Example 3:

[0065] This experiment verifies the effectiveness of the invention by comparing the control group and the experimental group.

[0066] The experimental group consisted of smart umbrellas prepared according to Examples 1 and 2; control group 1 consisted of traditional ordinary umbrellas that only had rain protection function and no color-changing layer; control group 2 consisted of umbrellas coated with ordinary photochromic ink in the prior art, without precise ultraviolet response design; the test items included light transmittance, color-changing performance, weather resistance, mechanical properties and warning function.

[0067] Experimental process

[0068] Transmittance test: The initial transmittance of three groups of samples was measured using a UV-Vis spectrometer in the wavelength range of 300-700nm, with no UV irradiation, at 550nm, and under UV irradiation in the 280-400nm range, with a 365nm UV lamp and a wavelength of 100mW / cm². 2The transmittance after 30 seconds of irradiation was measured, and the average value was taken after three repetitions.

[0069] Color-changing performance test: The above-mentioned ultraviolet lamp was used to irradiate the experimental group and control group 2 in a cycle-to-extinguish operation. After each irradiation, the lamp was extinguished after 30 seconds. The color change, colorless to dark color, and fading time were recorded. This was repeated 10,000 times. The color coordinate Lab* value before and after each cycle was measured with a colorimeter, and ΔE was calculated. Control group 1 has no color-changing function and was not included in this test.

[0070] Weather resistance test: The umbrella surfaces of the three groups of samples were placed in a QUV aging test chamber with UVB-313 lamps and an irradiance of 0.71W / m². 2 The temperature was 60℃ and the humidity was 50%, and the aging was carried out continuously for 2000 hours. After aging, the color change performance of the experimental group and the control group 2 were repeated, and the color change efficiency retention rate was calculated as color change efficiency after aging / initial color change efficiency × 100%. The light transmittance retention rate of the control group 1 after aging was tested.

[0071] Mechanical performance testing: The interlayer bond strength of the umbrella surface of three groups of samples was tested using a tensile testing machine. The sample size was 10cm×2cm and the tensile speed was 50mm / min. The water pressure resistance of the umbrella surface after welding was tested using a water pressure tester with a pressurization speed of 1kPa / s.

[0072] Warning function test: The experimental group and control groups 1 and 2 were placed in an adjustable darkroom, and the light intensity was adjusted from 200 lux to 50 lux and monitored with a light meter; For the experimental group and control group 2, if they had a warning function, the activation of the LED warning light was observed when the light intensity was <100 lux, and the accuracy was recorded after 10 repetitions; Control group 1 had no warning function and did not participate in this test.

[0073] The experimental data are as follows:

[0074]

[0075]

[0076] Experimental data show that, compared with the conventional ordinary umbrella control group 1 and the existing umbrella control group 2 coated with ordinary photochromic ink, the smart umbrella experimental group of the present invention has significant advantages in all aspects of performance:

[0077] The initial light transmittance reached 87%, which is much higher than the 70% of control group 1 and the 65% of control group 2, indicating better visual transparency;

[0078] After UV irradiation, the light transmittance dropped to 35%, and the sun protection effect was significantly better than that of control group 1 (68%, almost unchanged) and control group 2 (40%).

[0079] The color change and fading times are both ≤1s, which is much faster than the 3s and 5s of control group 2. After 10,000 cycles, the ΔE decay is <5%, which is much lower than the 30% of control group 2. The color change response speed and stability are more outstanding.

[0080] After 2000 hours of aging, the color change efficiency retention rate was ≥90%, while that of control group 2 was only 45%. The light transmittance retention rate was 85%, which was higher than that of control group 1 (50%) and control group 2 (55%), indicating a significant improvement in weather resistance.

[0081] The interlayer bonding strength is ≥2N / cm, which is better than 1N / cm of control group 1 and 1.2N / cm of control group 2. The water pressure resistance of the umbrella surface is ≥50kPa, which is higher than 30kPa of control group 1 and 35kPa of control group 2, and the structure is more stable.

[0082] The LED warning light has a 100% activation accuracy, which is better than the 80% of the control group 2, and its safety is more reliable in low light conditions.

[0083] In summary, the smart umbrella with a transparent photosensitive color-changing layer and its preparation method solve the problem of fixed color-changing threshold through the synergistic effect of the transparent photosensitive color-changing layer 102 and the ultraviolet absorption layer 103: the spiropyran and naphthopyran synergistic color-changing molecules in the transparent photosensitive color-changing layer 102 react only under 280-400nm ultraviolet irradiation. The anthocyanin structure generated by the ring-opening of spiropyran causes the umbrella surface to turn into a deep amber color, while naphthopyran expands the color-changing range; the titanium dioxide-zinc oxide composite nanoparticles in the ultraviolet absorption layer 103 precisely limit the triggering band, avoid visible light interference, and improve the specificity and reliability of the color-changing response.

[0084] Furthermore, the smart umbrella containing a transparent photosensitive color-changing layer and its manufacturing method solve the problem of visual transparency with the five-layer composite structure of the umbrella surface 1: the transparent photosensitive color-changing layer 102 is a UV-cured transparent film, and the structural reinforcement layer 104 is a polycarbonate transparent film, both of which ensure an initial light transmittance of 87%; even after ultraviolet irradiation, the color-changing layer still maintains a certain degree of light transmittance, and does not affect vision in low-light scenarios such as rainy days, overcoming the safety hazards caused by the opacity of ordinary ink coatings.

[0085] Furthermore, the smart umbrella containing a transparent photosensitive color-changing layer and its manufacturing method improve weather resistance through a three-layer co-extrusion casting and hot-pressing composite process: the three-layer co-extrusion casting machine integrates the transparent photosensitive color-changing layer 102, the ultraviolet absorption layer 103, and the structural reinforcement layer 104 into a single molding process; during hot-pressing composite, the hydrophobic protective layer 101 and the transparent photosensitive color-changing layer 102 are treated with plasma, and the interface bonding strength is ≥2N / cm; the hydrophobic protective layer 101 is water-resistant, and the waterproof adhesive layer 105 is sealed; after 2000 hours of aging, the color-changing efficiency retention rate is ≥90%, meeting the needs of long-term use. This solves the problems of existing umbrellas, such as a fixed color-changing threshold, inability to accurately control according to the ultraviolet band, opaque layers affecting visual transparency, and color-changing performance decay and poor weather resistance after long-term use.

[0086] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0087] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A smart umbrella containing a transparent photosensitive color-changing layer, comprising an umbrella canopy (1), umbrella ribs (2), an umbrella handle (3), and a control system (4), characterized in that: The umbrella surface (1) has a five-layer composite structure, consisting of a hydrophobic protective layer (101), a transparent photosensitive color-changing layer (102), an ultraviolet absorption layer (103), a structural reinforcement layer (104), and a waterproof adhesive layer (105) from the outside to the inside. The hydrophobic protective layer (101) is fluorosilane-modified polytetrafluoroethylene with a thickness of 2 μm; the transparent photosensitive color-changing layer (102) is composed of spiropyran and naphthopyran synergistic color-changing molecules; the ultraviolet absorption layer (103) contains titanium dioxide-zinc oxide composite ultraviolet absorber nanoparticles dispersed in the EVA matrix; the structural reinforcement layer (104) is a transparent polycarbonate film with a thickness of 100 μm; and the waterproof adhesive layer (105) is a polyurethane hot melt adhesive with a thickness of 20 μm.

2. The smart umbrella with a transparent photosensitive color-changing layer according to claim 1, characterized in that: The total thickness of the umbrella surface (1) is 200–250 μm.

3. The smart umbrella with a transparent photosensitive color-changing layer according to claim 1, characterized in that: Under 280-400nm ultraviolet light irradiation, the transparent photosensitive color-changing layer (102) undergoes a ring-opening reaction of spiropyran molecules to generate a cyanine structure. The absorption peak of the cyanine structure is 550nm, and the umbrella surface (1) changes from colorless and transparent to deep amber. After the ultraviolet light disappears, the cyanine structure closes its ring and returns to colorless, with a color change time of ≤1s. Naphthopyran molecules can extend the color change range to 450-600nm, realizing a dynamic change of blue and purple.

4. The smart umbrella with a transparent photosensitive color-changing layer according to claim 1, characterized in that: The umbrella rib (2) is a carbon fiber hollow tube with a flexible copper wire embedded inside. The diameter of the flexible copper wire is 0.1 mm. One end of the flexible copper wire is connected to a micro photovoltaic cell at the umbrella handle (3), and the other end is connected to an LED warning light at the end of the umbrella rib (2). The micro photovoltaic cell has a size of 2 cm × 1 cm and a working voltage of 3.7 V ± 0.2 V.

5. The smart umbrella with a transparent photosensitive color-changing layer according to claim 1, characterized in that: The control system (4) includes a light intensity sensor and a switch module. The light intensity sensor is set on the surface of the umbrella handle (3). When the light intensity sensor detects a light intensity of <100 lux, the switch module is automatically turned on, and the LED warning light is activated. The power of the LED warning light is 0.5W.

6. A method for preparing a smart umbrella containing a transparent photosensitive color-changing layer, characterized in that: The smart umbrella with a transparent photosensitive color-changing layer as described in claims 1-5, and the following steps: S1: Preparation of a transparent photosensitive color-changing layer Spiropyran and naphthopyran were dissolved in methyl methacrylate, with spiropyran accounting for 0.5% by mass and naphthopyran accounting for 0.3% by mass. Irgacure 184 photoinitiator was added, with a mass percentage of 0.2%. After thorough mixing, a 50 μm thick transparent film was formed by UV curing. The UV curing parameters were: wavelength 365 nm and power 500 mW / cm². 2 Time: 30 seconds; S2: Preparation of the ultraviolet absorption layer Titanium dioxide-zinc oxide composite UV absorber nanoparticles were added to an EVA toluene solution, with the mass percentage of the titanium dioxide-zinc oxide composite UV absorber nanoparticles being 5% and the solid content of the EVA toluene solution being 15%. The nanoparticles were dispersed by ultrasonic dispersion at a power of 300W for 30 minutes. The nanoparticles were then coated onto the surface of the structural reinforcement layer using a slot coater and dried at 80°C for 30 minutes to form a 30μm thick coating. S3: Co-extrusion composite A three-layer co-extrusion casting machine was used to simultaneously extrude the transparent photosensitive color-changing layer (102), the ultraviolet absorption layer (103), and the structural reinforcement layer (104). The die temperature was 220℃, and the layers were shaped by a 20℃ cooling roller. Subsequently, the hydrophobic protective layer (101) and the waterproof adhesive layer (105) were respectively bonded to both sides by hot pressing. The hot pressing parameters were 60℃ temperature and 0.3MPa pressure to form a complete umbrella surface (1). S4: Molding and Assembly The composite umbrella surface (1) is hot-pressed and cut into a fan shape at 180℃ and 0.5MPa, and then spliced ​​into a circular umbrella surface by high-frequency welding. The flexible copper wire of the umbrella rib (2) is connected to the micro photovoltaic cell and LED warning light of the umbrella handle (3), and the control system (4) is assembled to complete the overall assembly.

7. The method for preparing the smart umbrella containing a transparent photosensitive color-changing layer according to claim 6, characterized in that: In S3, the extrusion speed of the three-layer co-extrusion casting machine is 1.2m / min, and the speed of the cooling roller is matched with the extrusion speed. During hot pressing, the bonding surface of the hydrophobic protective layer and the transparent photosensitive color-changing layer is treated with plasma. The parameters of the plasma treatment are power 500W and time 10s. After treatment, the interface bonding strength is ≥2N / cm.

8. The method for preparing the smart umbrella containing a transparent photosensitive color-changing layer according to claim 6, characterized in that: In S4, the parameters for high-frequency welding are: frequency 35kHz, pressure 0.2MPa, welding time 1.5s, weld width ≤0.5mm; and the water pressure resistance of the umbrella surface 1 after welding ≥50kPa.

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