Highly-visible wear-resistant antiskid environment-friendly road marking coating and preparation method thereof

Abstract

The invention discloses a high-visibility wear-resistant antiskid environment-friendly road marking coating and a preparation method thereof. The coating comprises environment-friendly film-forming resin, a white pigment filler, a functional filler, a reflective medium, reflective-antiskid composite particles, an auxiliary agent and water. The preparation method comprises the following steps: cleaning and drying the antiskid aggregate core, coating the antiskid aggregate core with a coupling agent to form an interface bonding layer, applying the reflective medium to the surface of the antiskid aggregate core before complete curing so that the reflective medium is partially embedded in the interface bonding layer, and curing and screening to obtain reflective-antiskid composite particles; and uniformly mixing the film-forming resin, the auxiliary agent and water, adding the pigment filler and the functional filler for dispersion, and finally adding the reflective medium and the reflective-antiskid composite particles for uniform mixing. Through the synergistic effect of the reflective-antiskid composite particles and the double-particle-size reflective medium, the marking has high retroreflection performance, excellent skid resistance, wear resistance and low VOC emission, and is suitable for highways, urban roads, airport roads and other scenes.

Description

Technical Field

[0001] This invention relates to the field of coating preparation technology, and in particular to a highly visible, wear-resistant, and anti-slip environmentally friendly road marking coating and its preparation method. Background Technology

[0002] Road markings are an important component of road traffic safety facilities. Their main function is to provide continuous and clear traffic guidance for vehicles and pedestrians through daytime visibility, nighttime retroreflective visibility, and rain-resistant recognition performance. With the increasing demands for traffic guidance accuracy and safety in scenarios such as highways, urban expressways, tunnels, and airport runways, road marking materials, in addition to possessing high initial brightness and retroreflective properties, must also maintain good wear resistance, skid resistance, and visibility retention under service conditions including repeated vehicle traffic, rain erosion, UV aging, and dirt accumulation. Existing road marking materials mainly include solvent-based, water-based, hot-melt, and two-component cold-plastic types. Among these, water-based and solvent-free systems have become important development directions for road marking materials due to their lower volatile organic compound emissions and smaller environmental impact.

[0003] However, existing road marking materials still face significant performance limitations in balancing high visibility, wear resistance, and skid resistance. To improve nighttime retroreflective performance, a certain number of reflective glass beads are typically exposed on the marking surface. However, excessively smooth surfaces or a single bead exposure method often lead to decreased wet-state skid resistance. Introducing more rough structures or hard aggregates to improve skid resistance, on the other hand, easily exacerbates surface contamination, reduces brightness, and weakens retroreflective properties. Simultaneously, skid-resistant aggregates are prone to detachment under vehicle pressure and shearing, affecting the wear resistance and long-term stability of the markings. For environmentally friendly systems, while water-based or solvent-free systems are more environmentally compliant, issues remain, such as significant environmental impact during drying and curing, insufficient early water resistance, and the need to improve mechanical strength and interfacial bonding. Current technologies generally focus more on initial performance, while paying insufficient attention to reflectivity retention, skid resistance retention, and continued functional exposure after wear during long-term service. Therefore, developing a road marking coating and its preparation method that can simultaneously achieve high visibility, wear resistance, and skid resistance under environmentally friendly conditions, while maintaining good overall performance during use, remains of great significance. Summary of the Invention

[0004] To address the aforementioned problems, this invention proposes a highly visible, wear-resistant, and anti-slip environmentally friendly road marking paint and its preparation method. By embedding a reflective medium portion onto the surface of an anti-slip aggregate core coated with a coupling agent, reflective-anti-slip composite particles are formed. These particles are then synergistically compounded with a dual-size reflective medium, giving the markings high retroreflectivity, excellent anti-slip properties, and wear resistance. Furthermore, the use of a water-based hybrid resin system and functional fillers significantly improves the coating's adhesion and durability while ensuring low VOC emissions.

[0005] This invention can be achieved through the following technical solutions:

[0006] A method for preparing a highly visible, wear-resistant, and slip-resistant environmentally friendly road marking paint includes the following steps:

[0007] Step 1: Clean and dry the anti-slip aggregate core, coat its surface with a coupling agent to form an interfacial bonding layer. Before the interfacial bonding layer is completely cured, apply the reflective medium to the surface of the anti-slip aggregate core so that the reflective medium is partially embedded in the interfacial bonding layer. Then cure and sieve to obtain reflective-anti-slip composite particles.

[0008] Step 2: Add the environmentally friendly film-forming resin, some additives, and water to the mixer and mix evenly. Add white pigments, functional fillers, and additives and disperse evenly. Then add the reflective medium and reflective-anti-slip composite particles and mix evenly to obtain a highly visible, wear-resistant, and anti-slip environmentally friendly road marking paint.

[0009] Preferably, the coating comprises, by weight, the following components: 18-35 parts of environmentally friendly film-forming resin, 15-40 parts of white pigments and fillers, 5-25 parts of functional fillers, 8-30 parts of reflective medium, 5-25 parts of reflective-anti-slip composite particles, 0.5-8 parts of additives, and 1-15 parts of water.

[0010] Preferably, the anti-slip aggregate core in step 1 is selected from one or at least two of calcined ceramic sand, fused silica sand, calcined bauxite sand, corundum sand, and high-alumina ceramic particles.

[0011] Preferably, the interfacial adhesive layer in step 1 contains one or at least two of the following: silane coupling agent, titanate coupling agent, zirconate coupling agent, epoxy-modified siloxane, and polyurethane adhesive phase.

[0012] Preferably, the environmentally friendly film-forming resin in step 2 is any one of the following systems: a hybrid system formed by waterborne polyurethane resin and waterborne epoxy resin, a hybrid system formed by waterborne acrylic resin and waterborne polyurethane resin, or a crosslinking system formed by waterborne epoxy resin and waterborne amine curing agent.

[0013] Preferably, the additives in step 2 include interface promoters and antifouling additives.

[0014] Preferably, the white pigments and fillers in step 2 include one or at least two of titanium dioxide, heavy calcium carbonate, barium sulfate, and calcined kaolin.

[0015] Preferably, the functional filler in step 2 includes one or at least two of the following: surface-modified nano-silica, nano-alumina, flake silicate, and ultrafine barium sulfate.

[0016] Preferably, the reflective medium in step 2 includes a first reflective microsphere and a second reflective microsphere; the average particle size of the first reflective microsphere is 100-400 μm; and the average particle size of the second reflective microsphere is 400-1200 μm.

[0017] The beneficial effects of this invention are:

[0018] This invention embeds a reflective medium portion into the interfacial bonding layer on the surface of the anti-slip aggregate core, forming reflective-anti-slip composite particles. Combined with the synergistic effect of dual-size reflective microspheres, this allows the road markings to form a stable retroreflective structure under both dry and wet conditions, significantly improving visibility at night and in rainy conditions. The retroreflective brightness coefficient can reach up to 346 mcd·m. -2 ·lx -1 It still maintains 268 mcd·m under wet conditions. -2 ·lx -1 This technology meets the stringent requirements of high-grade roads for all-weather pavement recognition. The hard aggregate core in the reflective-anti-skid composite particles forms a peripheral rough structure on the coating surface, giving the pavement excellent anti-skid performance. At the same time, the composite particles, hybrid resin system, and functional fillers work synergistically to enhance the density and interfacial bonding of the coating, significantly reduce wear and weight loss, and effectively extend the service life of the pavement.

[0019] This invention uses a water-based hybrid resin system and low-VOC additives, with the VOC content controlled below 35g / L; at the same time, the coating has good adhesion and early water resistance, adapts to various construction conditions, and meets the needs of modern road engineering for green, durable, and multifunctional road marking materials. Attached Figure Description

[0020] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0021] Figure 1 The retroreflection brightness coefficient and wet retroreflection brightness coefficient of the coating;

[0022] Figure 2 The coating's anti-slip properties, abrasion resistance, adhesion, and VOC content are considered. Detailed Implementation

[0023] The following provides a detailed description of the embodiments of the present invention: These embodiments are implemented based on the technical solution of the present invention, and provide detailed implementation methods and processes. However, the scope of protection of the present invention is not limited to the following embodiments. Experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions.

[0024] Example 1: A highly visible, wear-resistant, and anti-slip environmentally friendly road marking paint, comprising the following components by weight: 18 parts environmentally friendly film-forming resin, 15 parts white pigments and fillers, 5 parts functional fillers, 8 parts reflective medium, 5 parts reflective-anti-slip composite particles, 0.5 parts additives, and 1 part water; the preparation method of the paint is as follows:

[0025] Step 1: First, clean the calcined ceramic sand and dry it at 105℃ for 2 hours. Then, spray a silane coupling agent on its surface to form an interfacial bonding layer. Before the interfacial bonding layer is completely cured, apply a reflective medium to the surface of the aggregate so that it is partially embedded in the interfacial bonding layer. Then, cure and sieve to obtain reflective-anti-slip composite particles.

[0026] Step 2: Add waterborne polyurethane resin, waterborne epoxy resin, antifouling additive and water to a mixer and stir for 10 minutes. Then add titanium dioxide, nano silica and interface promoter and disperse for 20 minutes. After that, add the first reflective microspheres (average particle size of 100 μm), the second reflective microspheres (average particle size of 400 μm) and the above reflective-anti-slip composite particles and mix for 15 minutes to obtain a highly visible, wear-resistant and anti-slip environmentally friendly road marking paint.

[0027] Example 2: A highly visible, wear-resistant, and anti-slip environmentally friendly road marking paint, comprising the following components by weight: 26.5 parts environmentally friendly film-forming resin, 27.5 parts white pigments and fillers, 15 parts functional fillers, 19 parts reflective medium, 15 parts reflective-anti-slip composite particles, 4.25 parts additives, and 8 parts water; the preparation method of the paint is as follows:

[0028] Step 1: First, clean the calcined ceramic sand and dry it at 105℃ for 2 hours. Then, spray a silane coupling agent on its surface to form an interfacial bonding layer. Before the interfacial bonding layer is completely cured, apply a reflective medium to the surface of the aggregate so that it is partially embedded in the interfacial bonding layer. Then, cure and sieve to obtain reflective-anti-slip composite particles.

[0029] Step 2: Add waterborne polyurethane resin, waterborne epoxy resin, antifouling additive and water to a mixer and stir for 10 minutes. Then add titanium dioxide, nano silica and interface promoter and disperse for 20 minutes. After that, add the first reflective microspheres (average particle size of 200 μm), the second reflective microspheres (average particle size of 600 μm) and the above reflective-anti-slip composite particles and mix for 15 minutes to obtain a highly visible, wear-resistant and anti-slip environmentally friendly road marking paint.

[0030] Example 3: A highly visible, wear-resistant, and anti-slip environmentally friendly road marking paint, comprising the following components by weight: 18 parts environmentally friendly film-forming resin, 15 parts white pigments and fillers, 20 parts functional fillers, 20 parts reflective medium, 15 parts reflective-anti-slip composite particles, 5 parts additives, and 10 parts water; the preparation method of the paint is as follows:

[0031] Step 1: First, clean the calcined ceramic sand and dry it at 105℃ for 2 hours. Then, spray a silane coupling agent on its surface to form an interfacial bonding layer. Before the interfacial bonding layer is completely cured, apply a reflective medium to the surface of the aggregate so that it is partially embedded in the interfacial bonding layer. Then, cure and sieve to obtain reflective-anti-slip composite particles.

[0032] Step 2: Add waterborne polyurethane resin, waterborne epoxy resin, antifouling additive and water to a mixer and stir for 10 minutes. Then add titanium dioxide, nano silica and interface promoter and disperse for 20 minutes. After that, add the first reflective microspheres (average particle size of 300 μm), the second reflective microspheres (average particle size of 800 μm) and the above reflective-anti-slip composite particles and mix for 15 minutes to obtain a highly visible, wear-resistant and anti-slip environmentally friendly road marking paint.

[0033] Example 4: A highly visible, wear-resistant, and anti-slip environmentally friendly road marking paint, comprising the following components by weight: 35 parts environmentally friendly film-forming resin, 40 parts white pigments and fillers, 25 parts functional fillers, 30 parts reflective medium, 25 parts reflective-anti-slip composite particles, 8 parts additives, and 15 parts water; the preparation method of the paint is as follows:

[0034] Step 1: First, clean the calcined ceramic sand and dry it at 105℃ for 2 hours. Then, spray a silane coupling agent on its surface to form an interfacial bonding layer. Before the interfacial bonding layer is completely cured, apply a reflective medium to the surface of the aggregate so that it is partially embedded in the interfacial bonding layer. Then, cure and sieve to obtain reflective-anti-slip composite particles.

[0035] Step 2: Add waterborne polyurethane resin, waterborne epoxy resin, antifouling additive and water to a mixer and stir for 10 minutes. Then add titanium dioxide, nano silica and interface promoter and disperse for 20 minutes. After that, add the first reflective microspheres (average particle size of 400 μm), the second reflective microspheres (average particle size of 1200 μm) and the above reflective-anti-slip composite particles and mix for 15 minutes to obtain a highly visible, wear-resistant and anti-slip environmentally friendly road marking paint.

[0036] Comparative Example 1: The difference between this comparative example and Example 1 is that it does not use reflective-anti-slip composite particles.

[0037] A highly visible, wear-resistant, and anti-slip environmentally friendly road marking paint comprises the following components by weight: 18 parts of environmentally friendly film-forming resin, 15 parts of white pigments and fillers, 5 parts of functional fillers, 8 parts of reflective medium, 0.5 parts of additives, and 1 part of water. The preparation method of the paint is as follows: waterborne polyurethane resin, waterborne epoxy resin, anti-fouling additives, and water are added to a mixer and stirred for 10 minutes. Then, titanium dioxide, nano-silica, and interface promoters are added and dispersed for 20 minutes. After that, first reflective microspheres (average particle size of 100 μm) and second reflective microspheres (average particle size of 400 μm) are added and mixed for 15 minutes to obtain the highly visible, wear-resistant, and anti-slip environmentally friendly road marking paint.

[0038] Comparative Example 2: The difference between this comparative example and Example 1 is that a single-size reflective microsphere is used instead of a reflective medium.

[0039] A highly visible, wear-resistant, and anti-slip environmentally friendly road marking paint comprises, by weight: 18 parts environmentally friendly film-forming resin, 15 parts white pigments and fillers, 5 parts functional fillers, 8 parts reflective microspheres (average particle size 250 μm), 5 parts reflective-anti-slip composite particles, 0.5 parts additives, and 1 part water; the preparation method of the paint is as follows:

[0040] Step 1: First, clean the calcined ceramic sand and dry it at 105℃ for 2 hours. Then, spray a silane coupling agent on its surface to form an interfacial bonding layer. Before the interfacial bonding layer is completely cured, apply reflective microspheres to the surface of the aggregate so that they are partially embedded in the interfacial bonding layer. Then, cure and sieve to obtain reflective-anti-slip composite particles.

[0041] Step 2: Add waterborne polyurethane resin, waterborne epoxy resin, antifouling additive and water to a mixer and stir for 10 minutes. Then add titanium dioxide, nano silica and interface promoter and disperse for 20 minutes. After that, add reflective microspheres (average particle size of 250μm) and the above reflective-anti-slip composite particles and mix for 15 minutes to obtain a highly visible, wear-resistant and anti-slip environmentally friendly road marking paint.

[0042] Comparative Example 3: The difference between this comparative example and Example 1 is that it does not use environmentally friendly hybrid film-forming resin and additives.

[0043] A highly visible, wear-resistant, and slip-resistant environmentally friendly road marking paint comprises, by weight: 18 parts of a single water-based acrylic resin, 15 parts of white pigments and fillers, 5 parts of functional fillers, 8 parts of reflective medium, 5 parts of reflective-slip composite particles, and 1 part of water; the preparation method of the paint is as follows:

[0044] Step 1: First, clean the calcined ceramic sand and dry it at 105℃ for 2 hours. Then, spray a silane coupling agent on its surface to form an interfacial bonding layer. Before the interfacial bonding layer is completely cured, apply a reflective medium to the surface of the aggregate so that it is partially embedded in the interfacial bonding layer. Then, cure and sieve to obtain reflective-anti-slip composite particles.

[0045] Step 2: Add the single water-based acrylic resin and water to a mixer and stir for 10 minutes. Then add titanium dioxide and nano silica and disperse for 20 minutes. After that, add the first reflective microspheres (average particle size of 100 μm), the second reflective microspheres (average particle size of 400 μm), and the above-mentioned reflective-anti-slip composite particles and mix for 15 minutes to obtain a highly visible, wear-resistant, and anti-slip environmentally friendly road marking paint.

[0046] Performance testing

[0047] The coatings prepared in Examples 1-4 and Comparative Examples 1-3 were applied to asphalt boards (for retroreflection and anti-skid tests), galvanized steel boards (for adhesion tests), and aluminum boards (for abrasion resistance tests), respectively. The coating thickness (wet film thickness 600 μm, dry film thickness 400 μm), surface drying time (15 min), and curing conditions (temperature 23±2℃, relative humidity 50%±5%, curing for 7 days) were kept consistent across groups. Tests were conducted after the samples were fully cured.

[0048] 1. Retroreflection Luminance Coefficient and Wet Retroreflection Luminance Coefficient Test

[0049] The retroreflective luminance coefficient and wet retroreflective luminance coefficient of the coating applied to the asphalt board were determined in accordance with GB / T 16311-2024 standard.

[0050] Table 1. Retroreflection luminance coefficient and wet-state retroreflection luminance coefficient of coatings

[0051] sample <![CDATA[Retroreflective luminance coefficient (mcd·m -2 ·lx -1 )]]> <![CDATA[Wet retroreflective luminance coefficient (mcd·m -2 ·lx -1 ).]]> Example 1 285 214 Example 2 313 231 Example 3 321 250 Example 4 346 268 Comparative Example 1 197 129 Comparative Example 2 210 145 Comparative Example 3 172 107

[0052] As shown in Table 1, the retroreflection luminance coefficients of Examples 1-4 are all greater than 280 mcd·m -2 ·lx -1 The wet retroreflection luminance coefficient is greater than 210 mcd·m -2 ·lx -1The results were significantly better than those of Comparative Examples 1-3, indicating that the synergistic effect of the reflective-anti-slip composite particles and the dual-size reflective medium enabled the formation of a stable retroreflective structure under both dry and humid conditions, improving the visibility and resistance to water film interference of the road markings. The retroreflective performance of Comparative Examples 1-3 was significantly lower than that of the example. Comparative Example 1, lacking reflective-anti-slip composite particles, suffered from a reduced retroreflective value due to the reflective medium being easily buried by the coating; Comparative Example 2, using single-size reflective microspheres, had a simple reflective layer structure and poor reflective effect under wet conditions; Comparative Example 3, using a single water-based acrylic resin, had insufficient film-forming properties and interfacial adhesion, resulting in poor fixation of the reflective medium and the worst retroreflective performance.

[0053] 2. Anti-slip performance test

[0054] The anti-skid performance of the coating applied to asphalt board was determined with reference to the standard T 0964-2008 in JTG 3450-2019.

[0055] 3. Wear resistance test

[0056] The abrasion resistance of the coating applied to the aluminum plate was determined according to GB / T 1678-2006 standard.

[0057] 4. Adhesion Test

[0058] The adhesion of coatings to galvanized steel sheets was determined in accordance with GB / T 9286-2021 standard.

[0059] 5. VOC content test

[0060] The VOC content of the coating was determined in accordance with GB / T 23985-2009 standard.

[0061] Table 2. Anti-slip properties, abrasion resistance, adhesion, and VOC content of coatings

[0062] sample Anti-slip value Abrasion resistance loss (mg) Adhesion (Grade) VOC (g / L) Example 1 68 42 1 28 Example 2 72 37 0 30 Example 3 75 33 0 31 Example 4 79 35 0 34 Comparative Example 1 51 66 3 26 Comparative Example 2 53 60 2 29 Comparative Example 3 47 74 4 22

[0063] As shown in Table 2, Examples 1-4 outperformed the comparative examples in terms of anti-slip value, abrasion resistance, and adhesion, and the VOC content was controlled below 35 g / L, meeting environmental protection requirements. Examples 1-4 exhibited an anti-slip value as high as 79, an abrasion loss as low as 33, and an adhesion rating of 0. This is attributed to the introduction of reflective-anti-slip composite particles, which allowed the anti-slip aggregate and reflective medium to be synergistically exposed on the coating surface, ensuring both anti-slip properties and improved abrasion resistance. Simultaneously, the synergistic effect of the hybrid resin system and functional fillers enhanced the coating's durability and adhesion.

[0064] Comparative Example 1 lacks composite particles, resulting in a low anti-slip value (51), a large abrasion weight loss (66mg), and an adhesion level of only 3. Comparative Example 2's single-particle-size reflective medium leads to uneven surface structure, and its anti-slip and abrasion resistance performance is still lower than that of the example. Comparative Example 3 has a single resin system, poor film-forming properties and interfacial bonding, resulting in an anti-slip value of only 47, a high abrasion weight loss of 74mg, and the worst adhesion (level 4).

[0065] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a highly visible, wear-resistant, and slip-resistant environmentally friendly road marking paint, characterized in that, Includes the following steps: Step 1: Clean and dry the anti-slip aggregate core, coat its surface with a coupling agent to form an interfacial bonding layer. Before the interfacial bonding layer is completely cured, apply the reflective medium to the surface of the anti-slip aggregate core so that the reflective medium is partially embedded in the interfacial bonding layer. Then cure and sieve to obtain reflective-anti-slip composite particles. Step 2: Add the environmentally friendly film-forming resin, some additives, and water to the mixer and mix evenly. Add white pigments, functional fillers, and additives and disperse evenly. Then add the reflective medium and reflective-anti-slip composite particles and mix evenly to obtain a highly visible, wear-resistant, and anti-slip environmentally friendly road marking paint.

2. The preparation method of the high-visibility, wear-resistant, and anti-slip environmentally friendly road marking paint according to claim 1, characterized in that, The coating, by weight, comprises the following components: 18-35 parts of environmentally friendly film-forming resin, 15-40 parts of white pigments and fillers, 5-25 parts of functional fillers, 8-30 parts of reflective medium, 5-25 parts of reflective-anti-slip composite particles, 0.5-8 parts of additives, and 1-15 parts of water.

3. The preparation method of the high-visibility, wear-resistant, and anti-slip environmentally friendly road marking paint according to claim 1, characterized in that, In step 1, the anti-slip aggregate core is selected from one or at least two of calcined ceramic sand, fused silica sand, calcined bauxite sand, corundum sand, and high-alumina ceramic particles.

4. The preparation method of the high-visibility, wear-resistant, and anti-slip environmentally friendly road marking paint according to claim 1, characterized in that, In step 1, the interfacial adhesive layer contains one or at least two of the following: silane coupling agent, titanate coupling agent, zirconate coupling agent, epoxy-modified siloxane, and polyurethane adhesive phase.

5. The preparation method of the high-visibility, wear-resistant, and anti-slip environmentally friendly road marking paint according to claim 1, characterized in that, In step 2, the environmentally friendly film-forming resin is any of the following systems: a hybrid system formed by waterborne polyurethane resin and waterborne epoxy resin, a hybrid system formed by waterborne acrylic resin and waterborne polyurethane resin, or a crosslinking system formed by waterborne epoxy resin and waterborne amine curing agent.

6. The preparation method of the high-visibility, wear-resistant, and anti-slip environmentally friendly road marking paint according to claim 1, characterized in that, The additives in step 2 include interface promoters and antifouling additives.

7. The preparation method of the high-visibility, wear-resistant, and anti-slip environmentally friendly road marking paint according to claim 1, characterized in that, The white pigments and fillers in step 2 include one or at least two of titanium dioxide, heavy calcium carbonate, barium sulfate, and calcined kaolin.

8. The preparation method of the high-visibility, wear-resistant, and anti-slip environmentally friendly road marking paint according to claim 1, characterized in that, The functional filler in step 2 includes one or at least two of the following: surface-modified nano-silica, nano-alumina, flake silicate, and ultrafine barium sulfate.

9. The preparation method of the high-visibility, wear-resistant, and anti-slip environmentally friendly road marking paint according to claim 1, characterized in that, In step 2, the reflective medium includes a first reflective microsphere and a second reflective microsphere; the average particle size of the first reflective microsphere is 100-400 μm; and the average particle size of the second reflective microsphere is 400-1200 μm.

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