High refractive index glass microbeads for road marking and method for preparing the same

Abstract

The application relates to the technical field of glass microsphere preparation, in particular to high-refractive glass microspheres for road marking and a preparation method thereof. The preparation method comprises the following steps: S1, raw material pretreatment: after raw material A and raw material B are mixed, soda ash, borax and a structure modifier are added to obtain solid raw materials; the solid raw materials are added into a mixer for mixing, a dispersing agent and a weather-resistant additive are added, and pretreated raw materials are obtained through mixing; S2, high-temperature melting into beads; and S3, surface modification treatment. The application provides the high-refractive glass microspheres for road marking and the preparation method thereof, so as to solve the problems of large refractive index fluctuation, insufficient adhesion and weather resistance of the glass microspheres for road marking in the prior art.

Description

A high refractive index glass microsphere for road markings and its preparation method Technical Field

[0001] This application relates to the field of glass microsphere preparation technology, and in particular to a high refractive index glass microsphere for road marking and its preparation method. Background Technology

[0002] Road markings, as crucial safety facilities for road traffic, directly impact driving safety in terms of visibility at night and under low visibility conditions. The retroreflective properties of glass microspheres are a core factor determining the reflective effect of road markings. High-refractive-index glass microspheres, due to their ability to significantly improve retroreflection efficiency, have become a key material for road markings in special scenarios such as highways and heavy traffic sections.

[0003] In existing technologies, the preparation of high-refractive-index glass microspheres for road markings mainly relies on the melt method. The melt method uses high-purity quartz sand, soda ash, limestone, and other basic raw materials, and adds high-refractive-index oxides such as TiO2 and ZrO2. After being melted at high temperature, the microspheres are formed, and the refractive index can reach above 1.9. Its advantages are low cost and high output.

[0004] However, in the mass production process, the temperature and cooling rate control precision in the melting method is limited, and high refractive index oxides are prone to agglomeration in the glass matrix, which will lead to uneven microstructure inside the microspheres, such as crystallization, bubbles and other defects, which will change the local refractive index. In addition, glass microspheres are exposed to complex environments such as ultraviolet rays, rain, temperature difference and vehicle friction for a long time, which can easily cause problems such as yellowing, wear and peeling from the marking paint, resulting in rapid decay of retroreflective performance and shortened service life. Summary of the Invention

[0005] This application provides a high refractive index glass microsphere for road markings and its preparation method, in order to solve the problems of large refractive index fluctuations, insufficient adhesion and weather resistance of glass microspheres for road markings in related technologies.

[0006] In a first aspect, a method for preparing high-refractive-index glass microspheres for road markings is provided, comprising the following steps:

[0007] S1. Raw material pretreatment:

[0008] Quartz sand and limestone were crushed to a particle size ≤100μm and dried to obtain raw material A;

[0009] Titanium dioxide and zirconium oxide were pulverized to a particle size ≤3μm to obtain raw material B;

[0010] According to the mass fraction, 50-60 parts of raw material A and 15-20 parts of raw material B are mixed, and then 15 parts of soda ash, 8-10 parts of borax and 1-2 parts of structural modifier are added to obtain solid raw material.

[0011] The solid raw material is added to a mixer, along with 2-3 parts of dispersant and 2-3 parts of weather-resistant agent, and mixed for 1-1.5 hours to obtain the pretreated raw material.

[0012] S2, High-temperature melting into beads:

[0013] Under stirring conditions, the pretreated raw materials are melted at 1350~1450℃ for 2~5 hours. After melting, the mixture is kept at the temperature for 2~3 hours to clarify and homogenize until there are no obvious bubbles. The resulting molten liquid is then formed into beads using a gear spraying molding method and shaped in the shaping area.

[0014] S3. Surface modification treatment:

[0015] S301. Immerse the microbeads in a 5wt% trisodium citrate aqueous solution and sonicate at 38~40℃ for 20min, then rinse with deionized water and dry.

[0016] S302. Continue to immerse in an ethanol solution of 3-5 wt% silane coupling agent, stir for 15-20 min, remove and dry, spray fluorinated acrylate hydrophobic agent on the surface of microspheres, and cure at 60℃ for 30-40 min to obtain high refractive index glass microspheres for road marking.

[0017] In S1, the preparation method of the weather-resistant additive includes:

[0018] Cerium oxide and hydrotalcite were pulverized to a particle size ≤5μm, dispersed in deionized water, and then chitosan was added. After ultrasonic dispersion, a weather-resistant additive was obtained.

[0019] The mass ratio of cerium oxide, hydrotalcite, chitosan and deionized water is (2~3):(3~4):1:30.

[0020] Preferably, in S1, raw material A includes quartz sand and limestone in a mass ratio of (4~5):1; raw material B includes titanium dioxide and zirconium oxide in a mass ratio of 12:(4~5).

[0021] Preferably, in step S1, the structural modifier comprises silicon carbide, boron mud, and perlite in a mass ratio of 1:4:(0~2), and the preparation method of the structural modifier includes the following steps:

[0022] Boron mud and perlite were calcined at 400-450℃ and kept at that temperature for 1.5-2 hours. After cooling, they were mixed with silicon carbide, pulverized, and passed through a 200-mesh sieve to obtain a structural modifier.

[0023] Preferably, in S1, the dispersant comprises sodium citrate, hydroxyethyl cellulose, and deionized water in a mass ratio of 3:(1.5~2):100.

[0024] Preferably, the gear spray forming method of S2 uses a high-speed rotating toothed disc with a rotation speed of 900~1250 r / min and a melt flow rate of 8~16 kg / h; the forming zone temperature is 900~1000℃.

[0025] Preferably, the flow rate of the molten liquid is 10~15 kg / h.

[0026] Preferably, in step S301, after impregnation, rinsing, and drying with a 5wt% trisodium citrate aqueous solution, the method further includes the following steps:

[0027] The dried microspheres are immersed in a weather-resistant additive, stirred at 60-70℃ for 1-2 hours, sonicated for 30 minutes, filtered, and dried to form a weather-resistant layer.

[0028] Preferably, in S302, the silane coupling agent is selected from γ-methacryloyloxypropyltrimethoxysilane;

[0029] The fluorinated acrylate hydrophobic agent is selected from one of 2,2,3,3-tetrafluoropropyl methacrylate and dodecafluoroheptyl methacrylate.

[0030] Secondly, a high-refractive-index glass microsphere for road marking is provided, which is prepared by any of the above-described methods for preparing high-refractive-index glass microspheres for road marking.

[0031] The beneficial effects of the technical solution provided in this application include:

[0032] This application provides a method for preparing high-refractive-index glass microspheres for road markings. Quartz sand and limestone in raw material A form a stable glass matrix. Titanium dioxide and zirconium oxide in raw material B are compounded as a high-refractive-index core component, enhancing the refractive index of the glass microspheres. A dispersing modifier inhibits the agglomeration of titanium dioxide and zirconium oxide during the melting process, ensuring uniform distribution of the high-refractive-index oxides within the glass matrix. Weather-resistant additives, along with subsequent modifications by silane coupling agents and fluorinated hydrophobic agents, provide dual protection. Cerium oxide in the weather-resistant additive blocks ultraviolet light from causing photoaging of the glass matrix. The silane coupling agent constructs a chemical bonding bridge and forms stable Si-OC chemical bonds with functional groups in the hot-melt road marking paint, improving adhesion to the paint. The fluorinated hydrophobic agent reduces surface energy, preventing moisture and impurities from penetrating, ensuring the microspheres maintain a high refractive index even after UV-thermal cycling aging.

[0033] The high hardness of silicon carbide, a structural modifier, directly improves the wear resistance of microspheres. Boron mud, as an industrial waste, not only supplements boron to build a stable borosilicate network and inhibits crystallization and microcrack formation during the melting process, but also reduces raw material costs. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 is a flowchart of the preparation method of high refractive index glass microspheres for road markings provided in this application. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0037] Referring to Figure 1, this application provides a high refractive index glass microsphere for road markings and its preparation method.

[0038] The materials used in the embodiments and comparative examples of this application include: industrial-grade high-purity quartz sand (SiO2 content ≥99.0%), industrial-grade sodium carbonate (purity ≥99.2%), industrial-grade limestone (CaCO3 content ≥95.0%), borax (industrial grade, purity ≥95.0%), anatase titanium dioxide (industrial grade, purity ≥98.5%), zirconium oxide (industrial grade, purity ≥99.0%), sodium citrate (food grade, purity ≥99.0%), hydroxyethyl cellulose (industrial grade, molecular weight 200,000–300,000 Da), sodium alginate (molecular weight 100,000–200,000 Da), industrial-grade magnesium aluminum hydrotalcite, and chitosan (food grade, degree of deacetylation ≥85%, molecular weight 50,000–100,000 Da). Da), silicon carbide (industrial grade, purity ≥98.0%, particle size ≤5μm), and B2O3 content in boron mud ≥3.0%.

[0039] Example 1

[0040] The method for preparing high-refractive-index glass microspheres for road markings provided in this embodiment includes the following steps:

[0041] S1. Raw material pretreatment:

[0042] 280g of quartz sand and 56g of limestone were crushed to a particle size ≤100μm and dried to obtain raw material A;

[0043] 84g of titanium dioxide and 28g of zirconium oxide were pulverized to a particle size ≤3μm to obtain raw material B;

[0044] After mixing 330g of raw material A with 108g of raw material B, add 90g of soda ash (sodium carbonate), 50g of borax, and 6g of structural modifier to obtain solid raw material;

[0045] Add the solid raw material to the mixer, add 15g of dispersant and 15g of weather-resistant agent, mix for 1.5h to obtain the pretreated raw material;

[0046] S2, High-temperature melting into beads:

[0047] Under stirring conditions, the pretreated raw materials are added to a melting furnace and melted at 1400℃ for 3 hours. After melting, the mixture is held at this temperature for 2 hours to clarify and homogenize until no obvious bubbles are present. The resulting molten liquid is then formed into beads using a gear-spraying molding method.

[0048] The flow rate of the molten liquid is controlled at 10 kg / h. A high-speed rotating toothed disc rotates at a speed of 1000 r / min, throwing out the molten liquid at a temperature of approximately 1350℃. The serrations of the high-speed rotating toothed disc cut the molten liquid into droplets. The droplets are thrown out under centrifugal force, and during the throwing process, the shear force generated by the high-speed motion and friction with the air further tears them into smaller droplets. The small droplets form spherical droplets under surface tension and cool and solidify in the air to form initial microspheres. The initial microspheres enter a shaping zone at 950℃ for further softening, shaping, and improving roundness to obtain microspheres.

[0049] S3. Surface modification treatment:

[0050] S301. Immerse the microbeads in a 5 wt% trisodium citrate aqueous solution, sonicate at 40°C for 20 min, then rinse with deionized water and dry.

[0051] S302. Continue to immerse in an ethanol solution of 4wt% γ-methacryloxypropyltrimethoxysilane (solvent is anhydrous ethanol and deionized water in a volume ratio of 1:1), stir for 15 min, remove and dry, spray dodecyl fluoroheptyl methacrylate on the surface of the microspheres, and cure at 60℃ for 30 min to obtain high refractive index glass microspheres for road marking.

[0052] In S1, the preparation method of the weather-resistant additive is as follows:

[0053] 1.1g of cerium oxide and 1.5g of hydrotalcite were pulverized to a particle size ≤5μm, dispersed in 15g of deionized water, and then 0.5g of chitosan was added. After ultrasonic dispersion, a weather-resistant additive was obtained.

[0054] The preparation method of the structure modifier is as follows:

[0055] 4g of boron mud and 2g of perlite were calcined at 450℃ and kept at that temperature for 1.5h. After cooling, they were mixed with 1g of silicon carbide and pulverized. The mixture was then passed through a 200-mesh sieve to obtain a structural modifier.

[0056] The dispersant is a mixture of 0.45g sodium citrate, 0.3g hydroxyethyl cellulose and 15g deionized water.

[0057] Example 2

[0058] The method for preparing high-refractive-index glass microspheres for road markings provided in this embodiment includes the following steps:

[0059] S1. Raw material pretreatment:

[0060] 280g of quartz sand and 70g of limestone were crushed to a particle size ≤100μm and dried to obtain raw material A;

[0061] 96g of titanium dioxide and 40g of zirconium oxide were pulverized to a particle size ≤3μm to obtain raw material B;

[0062] After mixing 300g of raw material A with 120g of raw material B, add 90g of soda ash, 48g of borax, and 9g of structural modifier to obtain solid raw material;

[0063] Solid raw materials are added to a mixer, along with 18g of dispersant and 12g of weather-resistant agent. The mixture is stirred for 1 hour to obtain pretreated raw materials.

[0064] S2, High-temperature melting into beads:

[0065] Under stirring conditions, the pretreated raw materials are added to a melting furnace and melted at 1350℃ for 4 hours. After melting, the mixture is held at this temperature for 2 hours to clarify and homogenize until no obvious bubbles are present. The resulting molten liquid is then formed into beads using a gear-spraying molding method.

[0066] The flow rate of the molten liquid is controlled at 8 kg / h. A high-speed rotating toothed disc rotates at a speed of 900 r / min, throwing the molten liquid out. The serrations of the high-speed rotating toothed disc cut the molten liquid into droplets. The droplets are thrown out under centrifugal force, and during the throwing process, the shear force generated by the high-speed motion and friction with the air further tears them into smaller droplets. The small droplets form spherical droplets under surface tension and cool and solidify in the air to form initial microspheres. The initial microspheres enter a shaping zone at 900℃ for further softening, shaping and improving roundness to obtain microspheres.

[0067] S3. Surface modification treatment:

[0068] S301. Immerse the microbeads in a 5 wt% trisodium citrate aqueous solution, sonicate at 38°C for 20 min, then rinse with deionized water and dry.

[0069] S302. Continue immersing in an ethanol solution of 3wt% γ-methacryloxypropyltrimethoxysilane (solvent is anhydrous ethanol and deionized water in a volume ratio of 1:1), stir for 15 min, remove and dry, spray 2,2,3,3-tetrafluoropropyl methacrylate on the surface of the microspheres, and cure at 60℃ for 40 min to obtain high refractive index glass microspheres for road marking.

[0070] In S1, the preparation method of the weather-resistant additive is as follows:

[0071] 1g of cerium oxide and 2g of hydrotalcite were pulverized to a particle size ≤5μm, dispersed in 15g of deionized water, and then 0.5g of chitosan was added. After ultrasonic dispersion, a weather-resistant additive was obtained.

[0072] The preparation method of the structure modifier is as follows:

[0073] 10g of boron mud was calcined at 400℃ and kept at that temperature for 1.5h. After cooling, it was mixed with 2.5g of silicon carbide and pulverized. The mixture was then passed through a 200-mesh sieve to obtain a structural modifier.

[0074] The dispersant is a mixture of 0.45g sodium citrate, 0.18g hydroxyethyl cellulose and 15g deionized water.

[0075] Example 3

[0076] The method for preparing high-refractive-index glass microspheres for road markings provided in this embodiment includes the following steps:

[0077] S1. Raw material pretreatment:

[0078] 300g of quartz sand and 60g of limestone were crushed to a particle size ≤100μm and dried to obtain raw material A;

[0079] 84g of titanium dioxide and 28g of zirconium oxide were pulverized to a particle size ≤3μm to obtain raw material B;

[0080] After mixing 360g of raw material A with 108g of raw material B, 90g of soda ash, 60g of borax, and 6g of structural modifier were added to obtain solid raw material;

[0081] Solid raw materials are added to a mixer, along with 15g of dispersant and 18g of weather-resistant agent. The mixture is stirred for 1.5 hours to obtain pretreated raw materials.

[0082] S2, High-temperature melting into beads:

[0083] Under stirring conditions, the pretreated raw materials are added to a melting furnace and melted at 1450℃ for 2 hours. After melting, the mixture is held at this temperature for 2 hours to clarify and homogenize until no obvious bubbles are present, at which point the molten liquid is obtained. The molten liquid is then formed into beads using a gear-spraying molding method.

[0084] The flow rate of the molten liquid is controlled at 16 kg / h. A high-speed rotating toothed disc rotates at a speed of 1250 r / min, throwing the molten liquid out. The serrations of the high-speed rotating toothed disc cut the molten liquid into droplets. The droplets are thrown out under centrifugal force, and during the throwing process, the shear force generated by the high-speed motion and friction with the air further tears them into smaller droplets. The small droplets form spherical droplets under surface tension and cool and solidify in the air to form initial microspheres. The initial microspheres enter a shaping zone at 1000℃ for further softening and shaping, and to improve their roundness, thus obtaining microspheres.

[0085] S3. Surface modification treatment:

[0086] S301. Immerse the microbeads in a 5 wt% trisodium citrate aqueous solution, sonicate at 40°C for 20 min, then rinse with deionized water and dry.

[0087] S302. Continue immersing in a 5wt% ethanol solution of γ-methacryloxypropyltrimethoxysilane (solvent is anhydrous ethanol and deionized water in a volume ratio of 1:1), stir for 20 min, remove and dry, spray dodecyl fluoroheptyl methacrylate onto the surface of the microspheres, and cure at 60℃ for 30 min to obtain high refractive index glass microspheres for road marking.

[0088] In S1, the preparation method of the weather-resistant additive is as follows:

[0089] 1.5g of cerium oxide and 1.5g of hydrotalcite were pulverized to a particle size ≤5μm, dispersed in 15g of deionized water, and then 0.5g of chitosan was added. After ultrasonic dispersion, a weather-resistant additive was obtained.

[0090] The preparation method of the structure modifier is as follows:

[0091] 4g of boron mud and 1g of perlite were calcined at 400℃ and kept at that temperature for 2 hours. After cooling, they were mixed with 1g of silicon carbide and pulverized. The mixture was then passed through a 200-mesh sieve to obtain a structural modifier.

[0092] The dispersant is a mixture of 0.45g sodium citrate, 0.225g hydroxyethyl cellulose and 15g deionized water.

[0093] Example 4

[0094] The difference between this embodiment and Embodiment 1 is that step S1 includes the following steps:

[0095] S1. Raw material pretreatment:

[0096] 280g of quartz sand and 56g of limestone were crushed to a particle size ≤100μm and dried to obtain raw material A;

[0097] 84g of titanium dioxide and 28g of zirconium oxide were pulverized to a particle size ≤3μm to obtain raw material B;

[0098] After mixing 330g of raw material A with 90g of raw material B, 90g of soda ash, 50g of borax, and 9g of structural modifier were added to obtain solid raw material;

[0099] The solid raw material was added to a mixer, along with 12g of dispersant and 15g of weather-resistant agent. The mixture was stirred for 1.5 hours to obtain the pretreated raw material.

[0100] Furthermore, the preparation method of the structure modifier is as follows:

[0101] 12g of boron mud was calcined at 450℃ and kept at that temperature for 1.5h. After cooling, it was mixed with 3g of silicon carbide and pulverized. The mixture was then passed through a 200-mesh sieve to obtain a structural modifier.

[0102] And, step S301 includes the following steps:

[0103] S301. Immerse the microbeads in a 5 wt% trisodium citrate aqueous solution, sonicate at 40°C for 20 min, then rinse with deionized water and dry.

[0104] The dried microspheres were immersed in a weather-resistant additive, stirred at 60°C for 1 hour, sonicated for 30 minutes, filtered, and dried to form a weather-resistant layer. The preparation method of the weather-resistant additive was the same as that in step S1.

[0105] The remaining operations are the same as in Example 1.

[0106] Comparative Example 1

[0107] The difference between this comparative example and Example 1 is that no weather-resistant additives and structural modifiers are added in step S1, while the remaining steps are the same as in Example 1.

[0108] Comparative Example 2

[0109] The difference between this comparative example and Example 1 is that no structural modifier is added in step S1, while the remaining steps are the same as in Example 1.

[0110] Comparative Example 3

[0111] The difference between this comparative example and Example 1 is that no weather-resistant additives and structural modifiers are added in step S1, and step S301 is not performed. The remaining steps are the same as in Example 1.

[0112] Comparative Example 4

[0113] The difference between this comparative example and Example 1 is that no weather-resistant additive is added in step S1, and step S302 is not performed. The remaining steps are the same as in Example 1.

[0114] The glass microspheres prepared in the above embodiments and comparative examples were tested.

[0115] Refractive index, yield, and roundness testing:

[0116] Referring to GB / T 24722-2020 "Glass Beads for Road Markings", the initial refractive index of the glass microspheres was tested using the immersion method. After the initial refractive index was determined, the microspheres were placed in an ultraviolet aging chamber (UVB 313nm, irradiation intensity 0.71W / (m²)). 2 After aging for 30 days, the refractive index was measured again using the immersion method (nm) and then subjected to a thermal cycling test (-20℃×2h→50℃×2h, for a total of 50 cycles). The refractive index retention rate was then calculated.

[0117]

[0118] Glass microspheres ranging from 106 to 800 μm were sieved as the finished product, and the yield was calculated. The yield is the percentage of the mass of the sieved glass microspheres out of all glass microspheres.

[0119] Continuing with reference to GB / T 24722-2020 "Glass Beads for Road Markings", a glass bead separator was used to separate round glass beads from defective ones. The total mass N of all the separated round glass beads and the total mass C of the defective glass beads were weighed, accurate to 0.1g, and the roundness P of the glass beads was calculated.

[0120]

[0121] In the formula:

[0122] P - Roundness (%)

[0123] Total mass (g) of N-round glass beads;

[0124] C - Total mass (g) of defective glass beads.

[0125] The results are shown in Table 1.

[0126] Table 1. Refractive index, refractive index retention, yield, and sphericity of the glass microspheres in the examples and comparative examples.

[0127]

[0128] Example 1 showed the highest refractive index retention, thanks to the weather-resistant additives (cerium oxide + hydrotalcite + chitosan) in which cerium oxide blocks ultraviolet rays, hydrotalcite neutralizes acid and alkali corrosion, and chitosan enhances the adhesion of the coating layer. Furthermore, the fluorinated hydrophobic agent in step S302 further isolates water vapor. Comparative Example 2 also maintained a good refractive index retention. Comparative Examples 1, 3, and 4, due to the lack of weather-resistant modification, experienced significant decreases in refractive index as ultraviolet radiation and thermal cycling caused microcracks in the glass matrix.

[0129] Meanwhile, by comparing Example 4 and Example 1 (Example 4 adds the impregnation treatment of weather-resistant additive in step S301), it can be found that the impregnation of weather-resistant additive helps to improve the refractive index retention rate, but because the weather-resistant additive forms a weather-resistant layer on the surface of the glass microspheres, the refractive index decreases compared with Example 1.

[0130] The particle size of centrifugally atomized beads is negatively correlated with the centrifugal speed: the higher the speed, the greater the centrifugal force on the melt, and the smaller the split droplets; if the speed is too low, the droplets will be too large. In Example 1, the droplets were split evenly at a speed of 1000 r / min, with most of them concentrated in the range of 106~800 μm, resulting in the highest yield. The examples and comparative examples all maintained a good sphericity.

[0131] Furthermore, the adhesion strength between the glass microspheres prepared in the examples and the road marking paint, as well as the retroreflection coefficient retention rate of the glass microspheres, were tested. The road marking paint used in this test was a hot-melt type.

[0132] Glass microspheres were mixed with hot-melt road marking paint (the glass microsphere content was 20% of the paint mass). The mixture was molded into marking templates measuring 300mm × 100mm × 2mm. These templates were then cured at room temperature (23±2)℃ and relative humidity (50±5)% for 72 hours. The cured templates were then placed horizontally on a test bench. Retroreflection coefficients were measured at five different locations (four corners and the center) using a retroreflection coefficient measuring instrument (measurement angle: observation angle 0.2°, incident angle -4°). The values ​​were recorded, and the arithmetic mean of the five points was calculated as the initial retroreflection coefficient R0 (mcd). m -2 lx -1 ).

[0133] After measuring the R0 of the marking template, fix it on the worktable of the abrasion testing machine, ensuring full contact between the grinding wheel and the template surface. Set the wear cycle to 500 cycles and conduct the abrasion test. After completion, continue to measure the retroreflection coefficient at 5 measuring points using the above method, and use this as the retroreflection coefficient R1 after wear. Calculate the retroreflection coefficient retention rate η:

[0134]

[0135] Furthermore, glass microspheres were mixed with hot-melt road marking paint (the amount of glass microspheres was 20% of the paint mass). The mixed paint was molded into marking templates with a size of 300mm×100mm×2mm. After curing in an environment of room temperature (23±2)℃ and relative humidity (50±5)% for 72 hours, metal zipper pulls were glued to the surface of glass microspheres with epoxy resin adhesive (ensuring that the zipper pulls completely cover the microsphere area). The adhesive was allowed to cure for 24 hours.

[0136] Fix the sample on the working table of the pull-off tester, adjust the metal pull head to be coaxial with the connecting rod of the tester, set the tensile rate to 1 mm / min, start the instrument until the metal pull head separates from the sample, record the maximum tensile force F (N), and calculate the bond strength σ (MPa).

[0137]

[0138] Where S is the bonding area of ​​the metal zipper pull (a round metal zipper pull with a diameter of 20mm), S=314mm² 2 .

[0139] The results are shown in Table 2.

[0140] Table 2. Retention rate of retroreflection coefficient and bonding strength of glass microspheres in the examples and comparative examples.

[0141]

[0142] The high hardness of silicon carbide in the structural modifier directly improves the surface hardness of glass microspheres. The boron element in the boron mud forms a stable borosilicate network with the glass matrix, inhibiting the generation and propagation of microcracks during wear and reducing the peeling of the glass microsphere surface. The weather-resistant additive delays the aging phenomena such as powdering and peeling of glass microspheres and extends their service life. Fluorohydrophobic agents (2,2,3,3-tetrafluoropropyl methacrylate and dodecafluoroheptyl methacrylate) further reduce the surface energy, reduce the intrusion of moisture and impurities, and ensure that the refractive index of the microspheres remains stable after wear.

[0143] Regarding adhesion performance, Example 1 involved treatment with a silane coupling agent followed by curing with a fluorinated hydrophobic agent. The active groups at both ends of the silane coupling agent formed chemical bonds (Si-OC bonds) with the hydroxyl groups on the surface of the glass microspheres and the functional groups of the coating resin, respectively, which significantly improved the chemical adhesion. Comparative Example 4, without silane coupling agent and fluorinated acrylate hydrophobic agent, had a hydrophilic hydroxyl group on its surface, which resulted in poor compatibility with the hydrophobic hot-melt road marking paint. It relied solely on physical adsorption for bonding, resulting in the weakest adhesion.

[0144] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for preparing high-refractive-index glass microspheres for road markings, characterized in that, It includes the following steps: S1. Raw material pretreatment: Quartz sand and limestone are crushed to a particle size ≤100μm and dried to obtain raw material A; titanium dioxide and zirconium oxide are crushed to a particle size ≤3μm to obtain raw material B; 50-60 parts of raw material A and 15-20 parts of raw material B are mixed according to the mass ratio, and 15 parts of soda ash, 8-10 parts of borax, and 1-2 parts of structural modifier are added to obtain solid raw material; the solid raw material is added to a mixer, and 2-3 parts of dispersant and 2-3 parts of weathering agent are added, and the mixture is mixed for 1-1.5 hours to obtain pretreated raw material; S2. High-temperature melting and bead formation: Under stirring conditions, the pretreated raw materials are melted at 1350~1450℃ for 2~5 hours, and then kept at the temperature for 2~3 hours to clarify and homogenize until there are no obvious bubbles. The melt is then formed into beads using a gear spraying method and shaped in a shaping area to obtain microspheres. S3. Surface modification treatment: S301. The microspheres are immersed in a 5wt% trisodium citrate aqueous solution and sonicated at 38~40℃ for 20 minutes, then rinsed with deionized water and dried. S302. The microspheres are then immersed in an ethanol solution of 3~5wt% silane coupling agent, stirred for 15~20 minutes, dried, and coated with a fluorinated acrylate hydrophobic agent. The microspheres are then cured at 60℃ for 30~40 minutes to obtain high refractive index glass microspheres for road markings. In S1, raw material A includes quartz sand and limestone in a mass ratio of (4~5):

1. Raw material B consists of titanium dioxide and zirconium oxide in a mass ratio of 12:(4~5); In S1, the preparation method of the weather-resistant additive includes: pulverizing cerium oxide and hydrotalcite to a particle size ≤5μm, dispersing them in deionized water, adding chitosan, and ultrasonically dispersing to obtain the weather-resistant additive; the mass ratio of cerium oxide, hydrotalcite, chitosan, and deionized water is (2~3):(3~4):1:30; In S1, the structural modifier includes silicon carbide, boron mud, and perlite in a mass ratio of 1:4:(0~2), and the preparation method of the structural modifier includes the following steps: calcining boron mud and perlite at 400~450℃ and keeping them at that temperature for 1.5~2h, cooling them, mixing them with silicon carbide, pulverizing them, and passing them through a 200-mesh sieve to obtain the structural modifier; In S1, the dispersant includes sodium citrate, hydroxyethyl cellulose, and deionized water in a mass ratio of 3:(1.5~2):

100.

2. The method for preparing high-refractive-index glass microspheres for road markings as described in claim 1, characterized in that: The gear spray forming method of S2 uses a high-speed rotating toothed disc with a rotation speed of 900~1250 r / min and a melt flow rate of 8~16 kg / h; the forming zone temperature is 900~1000℃.

3. The method for preparing high-refractive-index glass microspheres for road markings as described in claim 2, characterized in that: The flow rate of the molten liquid is 10~15 kg / h.

4. The method for preparing high-refractive-index glass microspheres for road markings as described in claim 1, characterized in that: In S301, after impregnation, rinsing and drying with a 5wt% trisodium citrate aqueous solution, the following steps are also included: immersing the dried microbeads in a weather-resistant agent, stirring at 60~70℃ for 1~2 hours, sonicating for 30 minutes, filtering and drying to form a weather-resistant layer.

5. The method for preparing high-refractive-index glass microspheres for road markings as described in claim 1, characterized in that: In S302, the silane coupling agent is selected from γ-methacryloyloxypropyltrimethoxysilane; the fluorinated acrylate hydrophobic agent is selected from 2,2,3,3-tetrafluoropropyl methacrylate and dodecafluoroheptyl methacrylate.

6. A type of high-refractive-index glass microsphere for road markings, characterized in that, It is prepared by the method for preparing high refractive index glass microspheres for road markings as described in any one of claims 1 to 5.

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