Reflective strip and preparation method thereof

Abstract

The invention relates to the field of reflective materials, and particularly discloses a reflective strip and a preparation method thereof, the reflective strip comprises an adhesive layer, a base material layer, an enhancement layer and a reflective layer from bottom to top in sequence; wherein the adhesive layer is made of polyacrylic acid; the reinforcing layer is formed by mixed slurry; the reflective layer contains glass beads, and 40-70% of the volume of the glass beads is embedded into the enhancement layer. According to the invention, the adhesive microstructure and the composite inorganic nano filler are optimized in the enhancement layer, so that the reflection intensity is maintained, the process is simplified, a layer-by-layer loading aluminum paste is replaced, and the process cost is reduced.

Description

Technical Field

[0001] The present invention belongs to the field of reflective materials, and in particular relates to a reflective strip and a preparation method thereof. Background Art

[0002] Reflective strips are a type of safety equipment whose main function is to improve the visibility of objects by reflecting light, thereby enhancing safety in low-light conditions. They use the principle of retroreflection to reflect light that hits the reflective material back to the light source along its original path, making objects more visible at night or in environments with poor visibility, thus serving as a warning. The basic uses of reflective strips include: (1) Traffic safety: used for traffic signs, road signs, etc. to improve visibility at night or in low-visibility conditions and reduce traffic accidents; (2) Personal protection: used for clothing, shoes, hats, backpacks, etc. of outdoor workers (such as traffic police and cleaners) to enhance nighttime visibility and reduce accident risks; (3) Building and construction safety: used to mark dangerous areas, emergency exits, passages, etc., to ensure that people can quickly identify safe paths in emergency situations; (4) Sports and outdoor activities: used for cycling equipment, sportswear, tents, sleeping bags, etc. to improve visibility at night or in low-light environments and reduce accidental injuries; and other applications where warnings are required in low-light environments.

[0003] Reflective striping is typically manufactured by applying a coating to an organic film substrate to create micro-shapes with favorable optical reflectivity. A metal reflective layer is then sputtered or evaporated onto these micro-shapes to maximize reflectivity and light utilization, thereby improving light utilization. In recent years, most researchers have focused on the reflective intensity and principles of reflective materials, and have developed several high-reflective materials. For example, patent application CN 117038747 A provides a high-reflectivity photovoltaic reflective film and its preparation method. This film utilizes a microprismatic structure, a first reflective layer, and a second reflective layer to effectively enhance reflectivity. Furthermore, the barrier effect of the substrate layer and the microstructure layer improves protection for the first reflective layer, thereby extending the lifespan of the reflective film. However, in rainy and foggy weather, reflective striping such as these is susceptible to reduced reflective efficiency due to light scattering / absorption. Furthermore, on highly reflective surfaces such as metal, it can easily cause specular reflection interference, reducing legibility.

[0004] Therefore, there is an urgent need on the market for a reflective strip material that can maintain good reflective performance under various conditions. Summary of the Invention

[0005] In order to overcome the deficiencies of the above-mentioned prior art, the present invention provides a four-layer reflective strip, which comprises, from bottom to top, an adhesive layer, a substrate layer, a reinforcement layer, and a reflective layer. In the reinforcement layer, the present invention optimizes the adhesive microstructure and composite inorganic nanofillers, simplifies the process while maintaining the reflective intensity, replaces the layer-by-layer loaded aluminum paste, and reduces the process cost. In the reflective layer, the present invention uses glass microspheres as the reflective material, and improves its refractive index and neutralizes the surface static charge through nano-ATO modification, thereby reducing dust adsorption and ensuring long-term reflective stability. In order to achieve the above object, the technical solution adopted by the present invention is: On one hand, the present invention provides a reflective strip, which has a structure from bottom to top of an adhesive layer, a base material layer, a reinforcing layer, and a reflective layer; the adhesive layer is made of polyacrylic acid; the reinforcing layer is made of a mixed slurry; the reflective layer contains glass microbeads; and 40 to 70% of the volume of the glass microbeads is embedded in the reinforcing layer.

[0006] In some embodiments, the substrate material is any one of synthetic resin and natural textile material.

[0007] In some embodiments, the glass microspheres have an average particle size of 40 to 60 μm and contain elements such as Mg, Al, Si, Ca, Zn, Ba, and O.

[0008] The working principle of reflective strips is mainly based on retroreflection and diffuse reflection of glass beads. Specifically, when light hits the reflective strips, the high refractive index structure inside will reflect the light back in the direction of the light source, thereby significantly improving the visibility of objects at night or in low light conditions.

[0009] In some embodiments, the mixed slurry is prepared by mixing and extruding polyethylene modified with glycidyl methacrylate and polystyrene at 160-180° C., and then adding a reflective material and mixing them uniformly to obtain a mixed slurry.

[0010] In some embodiments, the mass ratio of the glycidyl methacrylate-modified polyethylene to polystyrene is 1:(0.06-0.16).

[0011] In some embodiments, the mass ratio of the glycidyl methacrylate modified polyethylene to the reflective material is 1:(0.1-0.3).

[0012] The present invention uses glycidyl methacrylate to modify the incompatible blend of polyethylene and polystyrene, so that the epoxy reaction of glycidyl methacrylate induces the formation of a micro-domain structure, reduces the size of the dispersed phase, and forms a submicron-level phase separation structure. This size is close to the visible light wavelength of 380 to 780 nm, which may produce light scattering or interference effects, thereby enhancing the diffuse reflection of the reflective strip surface. At the same time, the modification of glycidyl methacrylate will reduce the crystallinity, and the increase of amorphous regions may improve the light transmittance of the material, which is beneficial to internal reflection.

[0013] In some embodiments, the average particle size of the reflective material is 10 to 100 nm.

[0014] In some embodiments, the reflective material comprises at least one of titanium dioxide, silicon dioxide, and aluminum oxide.

[0015] Preferably, the reflective material comprises titanium dioxide, silicon dioxide and aluminum oxide in a mass ratio of (5-10): (10-20): (60-80).

[0016] The aluminum oxide in the nano-reflective material used in this invention is used to scatter light. Titanium dioxide utilizes its high refractive index to enhance light scattering and forms a refractive index gradient with the mixed resin matrix. This gradient refraction deflects the incident light path toward the normal, reducing the critical value of the total reflection angle and increasing the scattering intensity. Silicon dioxide also optimizes the refractive index gradient of the light path. Furthermore, the epoxy groups of glycidyl methacrylate react with the hydroxyl groups on the surface of the nano-reflective material, breaking down its aggregate structure and improving the dispersion of the reflective material in the adhesive reflective paste.

[0017] In some embodiments, the synthetic monomers of the polyacrylic acid include methyl acrylate, butyl acrylate, butyl methacrylate, vinyl acetate and acrylic acid.

[0018] In some embodiments, based on 100% by mass, the synthetic monomers include 11-16% methyl acrylate, 42-47% butyl acrylate, 17-22% butyl methacrylate, 18-23% vinyl acetate and 1-3% acrylic acid.

[0019] The invention increases the viscosity and weather resistance by adjusting the synthetic monomer of polyacrylic acid, thereby prolonging the service life of the reflective strip.

[0020] Another aspect of the present invention provides a method for preparing the reflective strip, the specific steps of which are as follows: S1, co-extruding a substrate and polyacrylic acid, and cooling and solidifying to obtain a substrate layer carrying an adhesive layer; S2, mixing the glass microspheres and the glass microsphere modifier evenly to obtain a glass microsphere mixed solution; S3, coating the mixed slurry on the other surface of the substrate layer, and then spraying the glass microsphere mixture, and curing to obtain the reinforcement layer and the reflective layer; S4, cutting and sorting to obtain reflective strips.

[0021] In order to obtain the reflective effect, ordinary reflective strips generally need to load aluminum paste layer by layer on the surface of the substrate layer. The present invention simplifies the process while maintaining the reflective intensity. By optimizing the adhesive microstructure and replacing the aluminum layer with composite inorganic nanofillers, the process cost is reduced.

[0022] In some embodiments, in step S2, based on 100% by mass, the glass microsphere modifier comprises 10-15% nano-ATO, 40-50% methanol, 5-10% N-methylpyrrolidone, 0.1-0.9% polyethylene glycol, 0.1-0.9% polyamide wax, and the balance is water.

[0023] In some embodiments, the thickness of the adhesive layer is 10 to 200 μm, the thickness of the substrate layer is 1 to 100 μm, the thickness of the reinforcement layer is 1 to 100 μm, and the thickness of the reflective layer is 10 to 400 μm.

[0024] The present invention combines a glass microsphere modifier with glass microspheres. The nano-ATO in the modifier forms a shell on the surface of the micron-sized glass microspheres, increasing their refractive index. The ATO's conductivity also neutralizes surface static charge, reducing dust absorption and ensuring long-term reflective stability. Furthermore, the addition of polyamide wax imparts a thixotropic network structure to the modifier, causing a sudden drop in viscosity during spraying, ensuring uniform distribution of the microspheres. The viscosity then recovers during the resting phase, preventing microsphere sedimentation.

[0025] Compared with the prior art, the present invention has the following beneficial effects: The reflective strip provided by the present invention has a total of four-layer structure, which is sequentially arranged from bottom to top as an adhesive layer, a base material layer, a reinforcement layer, and a reflective layer. In the adhesive layer, the present invention synthesizes polyacrylic acid through a variety of monomers to enhance the viscosity and weather resistance of the reflective strip, thereby increasing the service life. In the reinforcement layer, the present invention reduces the process cost by optimizing the adhesive microstructure and replacing the layer-by-layer loaded aluminum paste with composite inorganic nanofillers, wherein the matrix resin forms a submicron-level phase separation structure, which enhances the diffuse reflection of the reflective strip surface; and also improves the light transmittance of the material by adjusting the resin crystallinity, and strengthens the internal reflection of light; on this basis, the composite inorganic nano-level reflective material enhances light scattering, and the refractive index step formed by the composite inorganic nano-level reflective material with the mixed resin matrix deflects the incident light path toward the normal direction, reduces the critical value of the total reflection angle, and increases the scattering intensity. In the reflective layer, the present invention uses glass microspheres as the reflective material, and improves its refractive index and neutralizes the surface static charge through nano-ATO modification, reduces dust adsorption, and ensures long-term reflective stability. DETAILED DESCRIPTION

[0026] The present invention will be described below in conjunction with specific embodiments. It should be noted that the following examples are illustrative of the present invention and are intended only to illustrate the present invention and are not intended to limit the present invention. Other combinations and various modifications within the scope of the present invention may be made without departing from the spirit or scope of the present invention.

[0027] It is worth noting that the raw materials used in the following preparation examples and embodiments, unless otherwise specified, were obtained from any commercially available manufacturer: Glycidyl methacrylate modified polyethylene can be purchased from Sumitomo Chemical of Japan under the model number Igetabond™; Polyethylene glycol optional model PEG400; Polystyrene optional model PA757; Nano-ATO was purchased from Hangzhou Jikang New Materials Co., Ltd. Polyamide wax can be purchased from Zhejiang Fenghong New Materials Co., Ltd., model PA-800.

[0028] Preparation Example 1 The preparation steps of polyacrylic acid are as follows: Step 1: Mix 13% methyl acrylate, 45% butyl acrylate, 20% butyl methacrylate, 20% vinyl acetate and 2% acrylic acid, based on 100% by mass, to obtain a synthetic monomer; Step 2: Mix 200 g of ethyl acetate and 16 g of isopropyl alcohol to obtain a solvent; Step 3: dissolving 0.2 g of azobisisobutyronitrile in 66 g of solvent to obtain an initiator solution; Step 4: 100 g of the synthetic monomer, 150 g of the solvent, and 6 g of KH-560 were mixed evenly and added to the reactor. The temperature was raised to 55±2° C., half of the initiator solution was added, and the reaction temperature was controlled at 64±2° C. After reflux, insulation was started for 70 min. After the insulation was completed, 100 g of the synthetic monomer and the remaining initiator solution were mixed and added dropwise for 2 h. After the addition was completed, the reaction was kept warm for 3 h. After the insulation was completed, the mixture was cooled to room temperature and filtered to obtain polyacrylic acid.

[0029] Preparation Example 2 The preparation steps of mixed slurry A are as follows: 100g of polyethylene modified with glycidyl methacrylate and 11g of polystyrene are mixed and extruded at 170°C, and then 27g of reflective material with an average particle size of 60nm (2g of titanium dioxide, 4.4g of silicon dioxide, and 20.6g of aluminum oxide) are added and mixed evenly to obtain a mixed slurry.

[0030] Preparation Example 3 The preparation steps of mixed slurry B are different from those of Preparation Example 2 in that polystyrene is replaced by polyethylene modified with glycidyl methacrylate of the same mass.

[0031] Preparation Example 4 The preparation steps of mixed slurry C are different from those of Preparation Example 2 in that the amount of polystyrene used is 4 g.

[0032] Preparation Example 5 The preparation steps of mixed slurry D are different from those of Preparation Example 2 in that the amount of polystyrene used is 18 g.

[0033] Preparation Example 6 The preparation steps of mixed slurry E differ from those of Preparation Example 2 in that the reflective material contains 4.4 g of silicon dioxide and 22.6 g of aluminum oxide.

[0034] Preparation Example 7 The preparation steps of mixed slurry F are different from those of Preparation Example 2 in that the reflective material contains 2 g of titanium dioxide and 25 g of aluminum oxide.

[0035] Preparation Example 8 The preparation steps of mixed slurry G are different from those of Preparation Example 2 in that the reflective material contains 27 g of aluminum oxide.

[0036] Preparation Example 9 The preparation steps of glass microsphere modifier A are as follows: Based on 100% by mass, 12% nano-ATO, 45% methanol, 7% N-methylpyrrolidone, 0.6% polyethylene glycol, 0.6% polyamide wax and the balance water were stirred evenly to obtain a glass microsphere modifier A.

[0037] Preparation Example 10 The preparation steps of glass microsphere modifier B are as follows: Based on 100% by mass, 45% methanol, 7% N-methylpyrrolidone, 0.6% polyethylene glycol, 0.6% polyamide wax and the balance water were stirred evenly to obtain a glass microbead modifier B.

[0038] Example 1 A reflective strip, whose structure from bottom to top is an adhesive layer with a thickness of 100 μm, a base material layer with a thickness of 50 μm, a reinforcement layer with a thickness of 200 μm, and a reflective layer with a thickness of 30 μm; the adhesive layer is composed of polyacrylic acid; the reinforcement layer is composed of mixed slurry A; the reflective layer contains glass microbeads, and 55% of the volume of the glass microbeads is embedded in the reinforcement layer.

[0039] The preparation method of the reflective strip in this embodiment is as follows: S1, co-extruding a PET substrate and polyacrylic acid, and cooling and solidifying to obtain a substrate layer carrying an adhesive layer; S2. Evenly mix 50 g of glass microspheres having an average particle size of 50 μm and 120 g of glass microsphere modifier A to obtain a glass microsphere mixed solution; S3, coating the other surface of the substrate layer with the mixed slurry A, and then spraying the glass microsphere mixture, and curing to obtain the reinforcing layer and the reflective layer; S4, cutting and sorting to obtain reflective strips.

[0040] Example 2 This embodiment provides a reflective strip and a preparation method thereof. The specific implementation method is the same as that of Example 1, except that: in step S3, mixed slurry A is replaced by mixed slurry B.

[0041] Example 3 This embodiment provides a reflective strip and a method for preparing the same. The specific implementation is the same as that of Example 1, except that in step S3, mixed slurry A is replaced by mixed slurry C.

[0042] Example 4 This embodiment provides a reflective strip and a method for preparing the same. The specific implementation is the same as that of Example 1, except that in step S3, mixed slurry A is replaced by mixed slurry D.

[0043] Example 5 This embodiment provides a reflective strip and a method for preparing the same. The specific implementation is the same as that of Example 1, except that in step S3, the mixed slurry A is replaced by the mixed slurry E.

[0044] Example 6 This embodiment provides a reflective strip and a preparation method thereof. The specific implementation method is the same as that of Example 1, except that: in step S3, the mixed slurry A is replaced by the mixed slurry F.

[0045] Example 7 This embodiment provides a reflective strip and a preparation method thereof. The specific implementation method is the same as that of Example 1, except that: in step S3, the mixed slurry A is replaced by the mixed slurry G.

[0046] Example 8 This embodiment provides a reflective strip and a preparation method thereof. The specific implementation method is the same as that of Example 1, except that: in step S2, the glass microbead modifier A is replaced by the glass microbead modifier B.

[0047] Performance testing: Reflectivity test: The reflectivity was tested using a Lambda 950 UV-Vis-NIR spectrophotometer in reflectance mode at a wavelength of 632.8 nm.

[0048] The above results are shown in Table 1.

[0049] Table 1 In the data in Table 1, the reflective strip of Example 1 has excellent reflectivity and can improve visibility under low visibility conditions. Compared with Example 1, the mixed slurry used in Examples 3 and 4 changed the amount of polystyrene, which reduced the reflectivity. Furthermore, in Example 2, no polystyrene was added, and the resin matrix of the reinforcement layer was polyethylene modified with glycidyl methacrylate. The reflectivity was further reduced compared with Examples 3 and 4. Combined with the data of Examples 1-4, the possible reason is that polystyrene, as a non-crystalline thermoplastic resin, forms a submicron phase separation structure close to the wavelength of visible light when blended with polyethylene modified with glycidyl methacrylate, thereby improving the reflectivity. In addition, changes in the amount of polystyrene will affect the formation of microstructures and light transmittance.

[0050] Compared with Example 1, the inorganic reflective materials used in the enhancement layer of Examples 5 and 6 removed titanium dioxide and silicon dioxide respectively. The reflectivity of the former decreased more significantly, indicating that the refractive index step was mainly formed by titanium dioxide; Example 7 only used aluminum oxide. Although the reflectivity decreased, it also provided a certain enhancement function.

[0051] Compared with Example 1, the glass microsphere modifier used in Example 8 lacks nano-ATO, which is not conducive to the formation of a shell layer of nano-ATO on the surface of the micron-sized glass microspheres, resulting in a decrease in reflectivity.

[0052] The embodiments and comparative examples described above do not impose any form of limitation on the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with the present profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical content disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A reflective strip, characterized in that: The structure from bottom to top is an adhesive layer, a base material layer, a reinforcing layer, and a reflective layer; the adhesive layer is made of polyacrylic acid; the reinforcing layer is made of a mixed slurry; the reflective layer contains glass microbeads; and 40 to 70% of the volume of the glass microbeads is embedded in the reinforcing layer.

2. The reflective strip according to claim 1, characterized in that: The glass microspheres have an average particle size of 40 to 60 μm and contain elements of Mg, Al, Si, Ca, Zn, Ba, and O.

3. The reflective strip according to claim 1, characterized in that: The preparation steps of the mixed slurry are as follows: glycidyl methacrylate modified polyethylene and polystyrene are mixed and extruded at 160-180° C., and then reflective material is added and mixed evenly to obtain the mixed slurry.

4. The reflective strip according to claim 3, characterized in that: The mass ratio of the glycidyl methacrylate modified polyethylene to polystyrene is 1:(0.06-0.16).

5. The reflective strip according to claim 3, characterized in that: The average particle size of the reflective material is 10-100 nm.

6. The reflective strip according to claim 3, characterized in that: The reflective material includes at least one of titanium dioxide, silicon dioxide and aluminum oxide.

7. The reflective strip according to claim 1, characterized in that: The synthetic monomers of the polyacrylic acid include methyl acrylate, butyl acrylate, butyl methacrylate, vinyl acetate and acrylic acid.

8. The reflective strip according to claim 7, characterized in that: Calculated by mass percentage of 100%, the synthetic monomers include 11-16% of methyl acrylate, 42-47% of butyl acrylate, 17-22% of butyl methacrylate, 18-23% of vinyl acetate and 1-3% of acrylic acid.

9. A method for preparing the reflective strip according to any one of claims 1 to 8, comprising the following steps: S1, co-extruding a substrate and polyacrylic acid, and cooling and solidifying to obtain a substrate layer carrying an adhesive layer; S2, mixing the glass microspheres and the glass microsphere modifier evenly to obtain a glass microsphere mixed solution; S3, coating the mixed slurry on the other surface of the substrate layer, and then spraying the glass microsphere mixture, and curing to obtain the reinforcement layer and the reflective layer; S4, cutting and sorting to obtain reflective strips.

10. The method for preparing a reflective strip according to claim 9, wherein: In step S2, based on 100% by mass, the glass microsphere modifier comprises 10-15% nano-ATO, 40-50% methanol, 5-10% N-methylpyrrolidone, 0.1-0.9% polyethylene glycol, 0.1-0.9% polyamide wax, and the balance is water.

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