High-refractive-index glass bead for road marking and preparation method of high-refractive-index glass bead

Abstract

The invention relates to the technical field of preparation of glass beads, in particular to a high-refractive-index glass bead for road marking and a preparation method of the high-refractive-index glass bead. The preparation method comprises the following steps: S1, raw material pretreatment: mixing a raw material A and a raw material B, and adding sodium carbonate, borax and a structure modifier to obtain a solid raw material; adding the solid raw materials into a mixing machine for mixing, adding a dispersing agent and a weather-proof auxiliary agent, and mixing to obtain a pretreated raw material; s2, performing high-temperature melting to form beads; and S3, surface modification treatment. According to the high-refractive-index glass bead for the road marking and the preparation method of the high-refractive-index glass bead provided by the invention, the problems of large refractive index fluctuation and insufficient cohesiveness and weather resistance of the glass bead for the road marking in the related technology are solved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of glass microbead preparation, in particular to high-refractive glass microbeads for road marking and a preparation method thereof. BACKGROUND

[0002] As an important safety facility for road traffic, the visibility of road marking under night and low-visibility conditions is directly related to driving safety, and the retroreflective performance of glass microbeads is a key factor determining the retroreflective effect of the marking. High-refractive glass microbeads have become a key material for marking in special scenes such as highways and heavy traffic sections because they can significantly improve the efficiency of light retroreflection.

[0003] In the prior art, the preparation of high-refractive glass microbeads for road marking is mainly based on the melting method. The melting method uses high-purity quartz sand, soda ash, limestone and other basic raw materials, and adds TiO2, ZrO2 and other high-refractive oxides. After high-temperature melting, beads are formed, and the refractive index can reach 1.9 or above. The advantage is low cost and high yield.

[0004] However, in the batch production process, the temperature and cooling rate control precision of the melting method is limited, and the high-refractive oxides are prone to agglomeration in the glass matrix, which can cause uneven microstructure inside the microbeads, such as crystallization, bubbles and other defects, changing the local refractive index. In addition, glass microbeads are easily yellowed, worn and peeled off from the marking paint when exposed to complex environments such as ultraviolet light, rain, temperature difference and vehicle friction for a long time, resulting in rapid decay of the retroreflective performance and shortening of the service life. SUMMARY

[0005] The application provides a kind of high-refractive glass microbeads for road marking and a preparation method thereof to solve the problem of refractive index fluctuation, insufficient adhesion and weather resistance of glass microbeads for road marking in related technologies.

[0006] In a first aspect, a preparation method of high-refractive glass microbeads for road marking is provided, which includes the following steps: S1, raw material pretreatment: The quartz sand and limestone are crushed to a particle size of ≤100 μm and dried to obtain raw material A; The titanium dioxide and zirconium oxide are crushed to a particle size of ≤3 μm to obtain raw material B; According to the mass fraction, 50-60 parts of raw material A and 15-20 parts of raw material B are mixed, then 15 parts of soda ash, 8-10 parts of borax and 1-2 parts of structure modifier are added to obtain solid raw material; The solid raw material is added to a mixer, 2-3 parts of dispersant and 2-3 parts of weather-resistant additive are added, and mixed for 1-1.5 h to obtain pretreated raw material; S2, high-temperature melting and bead forming: Under stirring, the pretreated raw materials are smelted at 1350-1450℃ for 2-5h, and the molten liquid is obtained after being kept for 2-3h after melting until no obvious bubbles are observed, then the molten liquid is formed into beads by gear jet spinning forming method, and the beads are shaped in a shaping area; S3, surface modification treatment: S301, the microbeads are immersed in 5wt% aqueous solution of trisodium citrate, and are ultrasonically treated at 38-40℃ for 20min, then are washed with deionized water and dried; S302, the microbeads are continuously immersed in 3-5wt% ethanol solution of silane coupling agent, and are stirred for 15-20min, then are taken out and dried, and a fluorine-containing propylene acrylate hydrophobic agent is sprayed on the surface of the microbeads, and the microbeads are cured at 60℃ for 30-40min to obtain the high refractive index glass microbeads for road marking; In the S1, the preparation method of the weather-resistant additive comprises: The cerium oxide and hydrotalcite are crushed to a particle size of ≤5μm, are dispersed in deionized water, and then chitosan is added, and the weather-resistant additive is obtained after ultrasonic dispersion; The mass ratio of the cerium oxide, hydrotalcite, chitosan and deionized water is (2-3):(3-4):1:30.

[0007] Preferably, in the S1, the raw material A comprises quartz sand and limestone in a mass ratio of (4-5):1; and the raw material B comprises titanium dioxide and zirconium oxide in a mass ratio of 12:(4-5).

[0008] Preferably, in the S1, the structure modifier comprises silicon carbide, boron mud and perlite in a mass ratio of 1:4:(0-2), and the preparation method of the structure modifier comprises the following steps: The boron mud and perlite are calcined at 400-450℃ and kept for 1.5-2h, then are mixed with silicon carbide after cooling, and are crushed to obtain the structure modifier.

[0009] Preferably, in the S1, the dispersant comprises sodium citrate, hydroxyethyl cellulose and deionized water in a mass ratio of 3:(1.5-2):100.

[0010] Preferably, the gear jet spinning forming method of the S2 uses a high-speed rotating toothed disc with a rotating speed parameter of 900-1250r / min, and the flow rate of the molten liquid is 8-16kg / h; and the temperature of the shaping area is 900-1000℃.

[0011] Preferably, the flow rate of the molten liquid is 10-15kg / h.

[0012] Preferably, in the S301, after the 5wt% aqueous solution of trisodium citrate is immersed, washed and dried, the following steps are further included: The dried microbeads are immersed in a weather-resistant additive, stirred at 60-70 DEG C for 1-2h, filtered and dried after ultrasonic treatment for 30min to form a weather-resistant layer.

[0013] Preferably, in S302, the silane coupling agent is selected from gamma-methacryloxypropyltrimethoxysilane. The fluorine-containing propylene acrylate hydrophobic agent is selected from one of 2,2,3,3-tetrafluoropropyl methacrylate and methacrylic acid dodecafluoroheptyl ester.

[0014] In a second aspect, a high-refractive glass microbead for road marking is provided, which is prepared by the method for preparing the high-refractive glass microbead for road marking.

[0015] The technical scheme provided by the present application has the following beneficial effects: The present application provides a high-refractive glass microbead for road marking and a preparation method thereof. The quartz sand in raw material A and the limestone form a stable glass matrix, and the titanium dioxide and zirconia in raw material B are compounded as high-refractive core components to improve the refractive index of the glass microbead. The dispersing modifier inhibits the agglomeration of titanium dioxide and zirconia during the melting process, ensuring the uniform distribution of high-refractive oxides in the glass matrix. The weather-resistant additive, the subsequent silane coupling agent and the fluorine-containing hydrophobic agent form a double protection. The cerium oxide in the weather-resistant additive blocks the photoaging of the glass matrix caused by ultraviolet light, the silane coupling agent forms a stable Si-O-C chemical bond with the functional groups in the hot-melt type marking paint, improves the adhesion with the marking paint, and the fluorine-containing hydrophobic agent reduces the surface energy, isolates water vapor and impurities, so that the refractive index of the microbead remains at a high level after ultraviolet-cold heat cycle aging.

[0016] The high hardness of the silicon carbide of the structure modifier directly improves the wear resistance of the microbead surface. The boron mud, as an industrial waste, not only supplements boron elements to form a stable boron-silicon network and inhibit crystallization and micro-cracks during the melting process, but also reduces the raw material cost. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0018] Figure 1 The preparation method flow chart of the high-refractive glass microbead for road marking provided by the present application is shown in the figure. DETAILED DESCRIPTION

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work belong to the range of protection of the present application.

[0020] Referring to Figure 1 As shown in the drawings, the present application provides a high-refractive glass microsphere for road marking and a preparation method thereof.

[0021] In the embodiments and comparative examples of the present application, the materials used include: quartz sand is an industrial-grade high-purity quartz sand (SiO2 content ≥ 99.0%), soda ash is an industrial-grade sodium carbonate (purity ≥ 99.2%), limestone is an industrial-grade limestone (CaCO3 content ≥ 95.0%), borax (industrial grade, purity ≥ 95.0%), titanium dioxide is an industrial-grade anatase titanium dioxide (purity ≥ 98.5%), zirconium oxide (industrial grade, purity ≥ 99.0%), sodium citrate (food grade, purity ≥ 99.0%), hydroxyethyl cellulose (industrial grade, molecular weight 200000-300000 Da), sodium alginate (molecular weight 100000-200000 Da), hydrotalcite is an industrial-grade magnesium-aluminum hydrotalcite, chitosan (food grade, deacetylation degree ≥ 85%, molecular weight 50000-100000 Da), silicon carbide (industrial grade, purity ≥ 98.0%, particle size ≤ 5 μm), and the B2O3 content in boron mud is ≥ 3.0%.

[0022] Embodiment 1 The preparation method of the high-refractive glass microsphere for road marking provided in the present embodiment includes the following steps: S1, raw material pretreatment: 280 g of quartz sand and 56 g of limestone were crushed to a particle size ≤ 100 μm and dried to obtain raw material A; 84 g of titanium dioxide and 28 g of zirconium oxide were crushed to a particle size ≤ 3 μm to obtain raw material B; After mixing 330 g of raw material A and 108 g of raw material B, 90 g of soda ash (sodium carbonate), 50 g of borax, and 6 g of structure modifier were added to obtain a solid raw material; The solid raw material was added to a mixer, 15 g of dispersant and 15 g of weather-resistant aid were added, and mixed for 1.5 h to obtain a pretreated raw material; S2, high-temperature melting and bead forming: Under stirring, the pretreated raw material was put into a smelting furnace, melted at 1400 ℃ for 3 h, and after melting, the molten liquid was clarified and homogenized for 2 h until no obvious bubbles were observed, and then the molten liquid was formed into beads by a gear jet spinning forming method: The molten liquid flow is controlled at 10 kg / h, the high-speed rotating toothed disc rotates at a speed of 1000 r / min, the molten liquid at a temperature of about 1350℃ is spun out, the serrations of the high-speed rotating toothed disc cut the molten liquid into droplets, the droplets are spun out under the centrifugal action, and are further torn into smaller droplets due to the shear force generated by high-speed movement and air friction in the spinning process, the small droplets form spherical droplets under the surface tension, and the initial-form microbeads are cooled and solidified in the air to form the initial-form microbeads, the initial-form microbeads enter the shaping area at 950℃ to further soften and shape, and the roundness is improved, so that the microbeads are obtained.

[0023] S3, surface modification treatment: S301, the microbeads are immersed in a 5wt% aqueous solution of trisodium citrate, ultrasonic treatment is performed at 40℃ for 20 min, then the microbeads are washed with deionized water and dried; S302, the microbeads are continuously immersed in a 4wt% ethanol solution of γ-methacryloyloxypropyltrimethoxysilane (the solvent is a mixture of anhydrous ethanol and deionized water in a volume ratio of 1:1), stirred for 15 min, taken out and dried, and then methyl dodecafluoroheptyl acrylate is sprayed on the surface of the microbeads, and the microbeads are cured at 60℃ for 30 min, so that the high-refractive glass microbeads for road marking are obtained.

[0024] In S1, the preparation method of the weather-resistant additive is as follows: 1.1g cerium oxide and 1.5g hydrotalcite are crushed to a particle size of ≤5μm, dispersed in 15g deionized water, and then 0.5g chitosan is added, and an ultrasonic dispersion is performed to obtain the weather-resistant additive.

[0025] The preparation method of the structure modifier is as follows: 4g boron mud and 2g perlite are calcined at 450℃ for 1.5h, cooled, mixed with 1g silicon carbide, and crushed to obtain the structure modifier.

[0026] The dispersant is a mixture of 0.45g sodium citrate, 0.3g hydroxyethyl cellulose and 15g deionized water.

[0027] Example 2 The preparation method of the high-refractive glass microbeads for road marking provided in this embodiment includes the following steps: S1, raw material pretreatment: 280g quartz sand and 70g limestone are crushed to a particle size of ≤100μm and dried to obtain raw material A; 96g titanium dioxide and 40g zirconia are crushed to a particle size of ≤3μm to obtain raw material B; 300g of raw material A and 120g of raw material B are mixed, 90g of soda ash, 48g of borax, and 9g of structure modifier are added to obtain a solid raw material; The solid raw materials were added into a mixer, 18 g of dispersant and 12 g of weathering aid were added, mixed for 1 h to obtain pretreated raw materials; S2, high-temperature melting into beads: The pretreated raw materials were put into a smelting furnace under stirring, smelted at 1350℃ for 4 h, and after melting, the molten liquid was clarified and homogenized for 2 h until no obvious bubbles were observed to obtain a molten liquid, which was formed into beads by a gear jet spinning method: The flow rate of the molten liquid was controlled at 8 kg / h, and the high-speed rotating toothed disc was rotated at a speed of 900 r / min to spin out the molten liquid. The serrations of the high-speed rotating toothed disc cut the molten liquid into droplets, which were spun out under the action of centrifugal force and further torn into smaller droplets due to the shear force generated by high-speed movement and air friction in the spinning process. The small droplets formed spherical droplets under the action of surface tension and were cooled and solidified into primary form microbeads in the air. The primary form microbeads entered the shaping zone at 900℃ to further soften and shape, improving the roundness, and obtained microbeads.

[0028] S3, surface modification treatment: S301, the microbeads were immersed in a 5wt% aqueous solution of trisodium citrate at 38℃ for 20 min, then washed with deionized water and dried; S302, continue to immerse in a 3wt% ethanol solution of γ-methacryloyloxypropyltrimethoxysilane (solvent is a mixture of anhydrous ethanol and deionized water in a volume ratio of 1:1), stir for 15 min, then take out and dry. Spray 2,2,3,3-tetrafluoropropyl methacrylate on the surface of the microbeads, and solidify at 60℃ for 40 min to obtain high-refractive glass microbeads for road marking.

[0029] In S1, the preparation method of the weathering aid is: 1 g of cerium oxide and 2 g of hydrotalcite were crushed to a particle size of ≤5 μm, dispersed in 15 g of deionized water, and then 0.5 g of chitosan was added. After ultrasonic dispersion, a weathering aid was obtained.

[0030] The preparation method of the structure modifier is: 10 g of boron mud was calcined at 400℃ for 1.5 h, then mixed with 2.5 g of silicon carbide and crushed to obtain a structure modifier.

[0031] The dispersant is a mixture of 0.45 g of sodium citrate, 0.18 g of hydroxyethyl cellulose and 15 g of deionized water.

[0032] Example 3 The preparation method of high-refractive glass microbeads for road marking provided by the present embodiment includes the following steps: S1, raw material pretreatment: 300 g of quartz sand and 60 g of limestone were crushed to a particle size of ≤100 μm and dried to obtain raw material A; 84 g of titanium dioxide and 28 g of zirconia were crushed to a particle size of ≤3 μm to obtain raw material B; After mixing 360 g of raw material A and 108 g of raw material B, 90 g of soda ash, 60 g of borax, and 6 g of structure modifier were added to obtain a solid raw material; The solid raw material was added to a mixer, 15 g of dispersant and 18 g of weathering aid were added, and mixed for 1.5 h to obtain a pretreated raw material; S2, high-temperature melting into beads: Under stirring, the pretreated raw material was put into a smelting furnace, smelted at 1450℃ for 2 h, and after melting, the molten liquid was obtained by keeping it at 1450℃ for 2 h to clarify and homogenize until no obvious bubbles were observed. Gear jet spinning forming method was used to form beads: The flow rate of the molten liquid was controlled at 16 kg / h, and the high-speed rotating toothed disc was rotated at a speed of 1250 r / min. The molten liquid was spun out, the serrations of the high-speed rotating toothed disc cut the molten liquid into droplets, the droplets were spun out under the action of centrifugal force, and further torn into smaller droplets due to the shear force generated by high-speed movement and air friction during the spinning process. The small droplets formed spherical droplets under the action of surface tension and were cooled and solidified into primary form microbeads in the air. The primary form microbeads entered the shaping zone at 1000℃ to further soften and shape, improve the roundness, and obtain microbeads.

[0033] S3, surface modification treatment: S301, the microbeads were immersed in a 5wt% aqueous solution of trisodium citrate at 40℃ for 20 min, then washed with deionized water and dried; S302, continue to immerse in a 5wt% ethanol solution of γ-methacryloyloxypropyltrimethoxysilane (solvent is a mixture of anhydrous ethanol and deionized water in a volume ratio of 1:1), stir for 20 min, then dry, spray methacrylic acid dodecafluoroheptyl ester on the surface of the microbeads, and solidify at 60℃ for 30 min to obtain high refractive index glass microbeads for road marking.

[0034] In S1, the preparation method of the weathering aid is: 1.5 g of cerium oxide and 1.5 g of hydrotalcite were crushed to a particle size of ≤5 μm, dispersed in 15 g of deionized water, and then 0.5 g of chitosan was added. After ultrasonic dispersion, a weathering aid was obtained.

[0035] The preparation method of the structure modifier is: 4 g of boron mud and 1 g of perlite were calcined at 400℃ for 2 h, then mixed with 1 g of silicon carbide after cooling and crushed to obtain a structure modifier.

[0036] The dispersant is a mixture of 0.45 g of sodium citrate, 0.225 g of hydroxyethyl cellulose and 15 g of deionized water.

[0037] Example 4 The difference between this example and Example 1 is that step S1 comprises the following steps: S1, raw material pretreatment: 280 g of quartz sand and 56 g of limestone were crushed to a particle size of ≤100 μm and dried to obtain raw material A; 84 g of titanium dioxide and 28 g of zirconia were crushed to a particle size of ≤3 μm to obtain raw material B; After mixing 330 g of raw material A with 90 g of raw material B, 90 g of soda ash, 50 g of borax, and 9 g of structure modifier were added to obtain a solid raw material; The solid raw material was added to a mixer, 12 g of dispersant and 15 g of weathering aid were added, and mixed for 1.5 h to obtain a pretreated raw material.

[0038] and the preparation method of the structure modifier is: After calcining 12 g of boron mud at 450℃ for 1.5 h, it was mixed with 3 g of silicon carbide and crushed to obtain a structure modifier.

[0039] and step S301 comprises the following steps: S301, immerse the microbeads in a 5 wt% aqueous solution of trisodium citrate, and ultrasonic at 40℃ for 20 min, then rinse with deionized water and dry; After drying, the microbeads were immersed in a weathering aid and stirred at 60℃ for 1 h, then filtered, dried to form a weathering layer. The preparation method of the weathering aid is consistent with the preparation method of the weathering aid in step S1.

[0040] The remaining operations are consistent with Example 1.

[0041] Comparative Example 1 The difference between this comparative example and Example 1 is that no weathering aid and structure modifier are added in step S1, and the remaining steps are consistent with Example 1.

[0042] Comparative Example 2 The difference between this comparative example and Example 1 is that no structure modifier is added in step S1, and the remaining steps are consistent with Example 1.

[0043] Comparative Example 3 The difference between this comparative example and Example 1 is that no weathering aid and structure modifier are added in step S1, and step S301 is not performed, and the remaining steps are consistent with Example 1.

[0044] Comparative Example 4 The difference between the present comparative example and Example 1 is that no weathering aid is added in step S1, and step S302 is not performed, and the remaining steps are consistent with Example 1.

[0045] The glass microbeads prepared in the above examples and comparative examples were tested.

[0046] Refractive index and yield, roundness rate test: According to GB / T 24722-2020 "Glass Beads for Road Marking", the initial refractive index of the glass microbeads was tested by immersion method; after the initial refractive index was determined, the microbeads were placed in a ultraviolet aging box (UVB 313 nm, irradiation intensity 0.71 W / (m 2 nm) ) for aging for 30 days, and then cold and hot cycle test (-20℃×2h→50℃×2h, a total of 50 cycles) was carried out, and then the refractive index after aging was determined again by immersion method, and the refractive index retention rate was calculated: The glass microbeads of 106-800 μm were screened as finished products, and the yield was calculated. The yield of the glass microbeads screened was the mass percentage of all glass microbeads.

[0047] According to GB / T 24722-2020 "Glass Beads for Road Marking", the round glass beads and defective glass beads were separated by a glass bead shaper, and the total mass N of all round glass beads and the total mass C of defective glass beads separated were weighed to 0.1 g, and the roundness rate P of the glass beads was calculated: In the formula: P- roundness rate (%); N- total mass of round glass beads (g); C- total mass of defective glass beads (g).

[0048] The results are shown in Table 1.

[0049] Table 1 Refractive index, refractive index retention rate, yield, and roundness rate of glass microbeads of examples and comparative examples The refractive index retention rate of Example 1 is the highest, which is due to the cerium oxide in the weathering aid (cerium oxide + hydrotalcite + chitosan) blocking ultraviolet rays, the hydrotalcite neutralizing acid and alkali corrosion, and the chitosan enhancing the adhesion of the coating layer, and the fluorine-containing hydrophobic agent in step S302 further isolates water vapor; Comparative Example 2 still maintains a good refractive index retention rate, and Comparative Examples 1, 3 and 4 have obvious decrease in refractive index due to no weathering modification and ultraviolet and cold and hot cycle leading to microcracks in the glass matrix.

[0050] Meanwhile, it can be found by comparing Example 4 and Example 1 (Example 4 adds the impregnation treatment of weather-resistant additives in step S301) that the impregnation of weather-resistant additives helps to improve the refractive index retention rate, but the refractive index decreases compared with Example 1 due to the formation of a weather-resistant layer on the surface of the glass beads by the weather-resistant additives.

[0051] The particle size of the centrifugal atomized beads is negatively correlated with the centrifugal speed: the higher the speed, the greater the centrifugal force on the molten liquid, and the smaller the split droplets; if the speed is too low, the droplets are too large. In Example 1, the speed of 1000 r / min makes the droplets split uniformly, with most of them concentrated in the range of 106-800 μm, and the yield is the highest; Examples and comparative examples all maintain good roundness.

[0052] Further, the adhesion of the glass beads prepared in the examples to the marking paint and the retroreflective coefficient retention rate of the glass beads are tested. The marking paint in this test is a hot melt type road marking paint.

[0053] The glass beads are mixed with the hot melt type road marking paint (the glass bead content is 20% of the mass of the paint), and the mixed paint is molded into a marking sample plate with a size of 300 mm x 100 mm x 2 mm using a mold. After being cured in an environment with a room temperature of (23±2) °C and a relative humidity of (50±5)% for 72 h, the cured marking sample plate is placed horizontally on a test bench, and the retroreflective coefficient is measured at five different positions (corners and center) of the sample plate using a retroreflective coefficient measuring instrument (the measurement angle is 0.2° of the observation angle, and the incident angle is -4°). After recording the values of each point, the arithmetic mean of the five points is calculated as the initial retroreflective coefficient R0 (mcd m -2 lx -1 ).

[0054] The marking sample plate with R0 measured is fixed on the workbench of the abrasion tester, and the grinding wheel is ensured to be in full contact with the surface of the sample plate. The number of abrasion cycles is set to 500, and the abrasion test is performed. After completion, the retroreflective coefficient of the five measurement points is measured according to the above method as the retroreflective coefficient R1 after abrasion. The retroreflective coefficient retention rate η is calculated as follows: Further, the glass beads are mixed with the hot melt type road marking paint (the glass bead content is 20% of the mass of the paint), and the mixed paint is molded into a marking sample plate with a size of 300 mm x 100 mm x 2 mm using a mold. After being cured in an environment with a room temperature of (23±2) °C and a relative humidity of (50±5)% for 72 h, the cured marking sample plate is placed horizontally on a test bench, and the retroreflective coefficient is measured at five different positions (corners and center) of the sample plate using a retroreflective coefficient measuring instrument (the measurement angle is 0.2° of the observation angle, and the incident angle is -4°). After recording the values of each point, the arithmetic mean of the five points is calculated as the initial retroreflective coefficient R0 (mcd Fix the sample on the workbench of the pull-off tester, adjust the metal pull head to be coaxial with the connecting rod of the tester, set the stretching rate to be 1 mm / min, start the instrument until the metal pull head is separated from the sample, record the maximum pulling force value F (N), and calculate the bonding strength σ (MPa).

[0055] wherein S is the bonding area of the metal pull head (a 20 mm diameter circular metal pull head), S = 314 mm 2 .

[0056] The results are shown in Table 2.

[0057] Table 2: Retention rate of retroreflective coefficient and bonding strength of glass beads of examples and comparative examples The high hardness characteristic of silicon carbide in the structure modifier directly improves the surface hardness of the glass beads, the boron element in the boron mud forms a stable boron-silicon network with the glass matrix, inhibits the generation and expansion of microcracks in the wear process, and reduces the peeling of the glass bead surface layer; the weathering aid delays the aging phenomena such as powdering and peeling of the glass beads, prolongs the service life, the fluorine-containing hydrophobic agent (2,2,3,3-tetrafluoropropyl methacrylate, dodecafluoroheptyl methacrylate) further reduces the surface energy, reduces the invasion of moisture and impurities, and ensures that the refractive index of the microbeads remains stable after wear.

[0058] For the bonding performance, example 1 is treated by silane coupling agent + fluorine-containing hydrophobic agent curing, the active groups at both ends of the silane coupling agent form chemical bonds (Si-O-C bonds) with the hydroxyl groups on the surface of the glass beads and the functional groups of the coating resin, greatly improving the chemical bonding force; comparative example 4 has no silane coupling agent and fluorine-containing acrylic hydrophobic agent, the surface is hydrophilic hydroxyl group, which has poor compatibility with the hydrophobic hot melt road marking paint, and only relies on physical adsorption combination, with the worst bonding force.

[0059] The above description is merely a specific implementation of the present application, enabling those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for producing a high refractive index glass microbead for road marking, characterized by, It comprises the following steps: S1, raw material pretreatment: The quartz sand and limestone are crushed to a particle size of ≤100 μm and dried to obtain raw material A; The titanium dioxide and zirconia are crushed to a particle size of ≤3 μm to obtain raw material B; According to the mass fraction, 50-60 parts of raw material A and 15-20 parts of raw material B are mixed, then 15 parts of soda ash, 8-10 parts of borax, and 1-2 parts of structure modifier are added to obtain a solid raw material; The solid raw material is added to a mixer, 2-3 parts of dispersant and 2-3 parts of weather-resistant additive are added, and mixed for 1-1.5 h to obtain a pretreated raw material; S2, high-temperature melting into beads: Under stirring, the pretreated raw material is melted at 1350-1450℃ for 2-5 h, and after melting, it is kept for 2-3 h to clarify and homogenize until no obvious bubbles are observed to obtain a molten liquid, which is formed into beads by gear jet spinning forming method, and shaped in the shaping area; S3, surface modification treatment: S301, the microbeads are immersed in a 5wt% aqueous solution of trisodium citrate, and ultrasonic treated at 38-40℃ for 20 min, then washed with deionized water and dried; S302, continue to immerse in 3-5wt% silane coupling agent ethanol solution, stir for 15-20 min, take out and dry, spray fluorine-containing propylene acrylate hydrophobic agent on the surface of the microbeads, and solidify at 60℃ for 30-40 min to obtain high refractive index glass microbeads for road marking; In the S1, the preparation method of the weather-resistant additive comprises: The cerium oxide and hydrotalcite are crushed to a particle size of ≤5 μm, dispersed in deionized water, and then chitosan is added, and after ultrasonic dispersion, a weather-resistant additive is obtained; The mass ratio of the cerium oxide, hydrotalcite, chitosan and deionized water is (2-3):(3-4):1:

30.

2. The preparation method of high refractive index glass microbeads for road marking according to claim 1, characterized in that: In the S1, the raw material A includes quartz sand and limestone with a mass ratio of (4-5):1; and the raw material B includes titanium dioxide and zirconia with a mass ratio of 12:(4-5).

3. The preparation method of high refractive index glass microbeads for road marking according to claim 1, characterized in that: In the S1, the structure modifier includes silicon carbide, boron mud and perlite with a mass ratio of 1:4:(0-2), and the preparation method of the structure modifier comprises the following steps: The boron mud and perlite are calcined at 400-450℃ for 1.5-2 h, cooled, mixed with silicon carbide and crushed to obtain a structure modifier.

4. The preparation method of high refractive index glass microbeads for road marking according to claim 1, characterized in that: In the S1, the dispersant includes sodium citrate, hydroxyethyl cellulose and deionized water with a mass ratio of 3:(1.5-2):

100.

5. The preparation method of high refractive index glass microbeads for road marking according to claim 1, characterized in that: The gear jet spinning forming method of the S2 uses a high-speed rotating toothed disc with a speed parameter of 900-1250 r / min, and the flow rate of the molten liquid is 8-16 kg / h; the temperature of the shaping area is 900-1000℃. 6.The method for preparing high refractive index glass microspheres for road marking according to claim 5, wherein: the flow rate of the molten liquid is 10-15 kg / h. 7.The method for preparing high refractive index glass microspheres for road marking according to claim 1, wherein: in the S301, after the 5wt% aqueous solution of trisodium citrate is immersed, rinsed and dried, the following steps are further included: the dried microspheres are immersed in a weather-resistant additive, stirred at 60-70℃ for 1-2h, ultrasonically treated for 30min, filtered and dried to form a weather-resistant layer. 8.The method for preparing high refractive index glass microspheres for road marking according to claim 1, wherein: in the S302, the silane coupling agent is selected from γ-methacryloxypropyltrimethoxysilane; the fluorine-containing propenoate hydrophobic agent is selected from one of 2,2,3,3-tetrafluoropropyl methacrylate and dodecafluoroheptyl methacrylate. The high refractive index glass microspheres for road marking are prepared by the method according to any one of claims 1-8. ​ ​ ​ ​ 9. A high refractive index glass microbead for road marking, characterized by, ​

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