Automotive lens optical glass preform and preparation method thereof

Abstract

The present invention relates to an automotive lens optical glass preform and a method for preparing the same. The optical glass preform comprises the following components, measured in molar percentage: 40-50% SiO2, 10-15% B2O3, 5-10% TiO2, 5-10% Nb2O5, 3-8% ZnO, 2-5% Al2O3, 0.1-0.5% CeO2, and 1-3% ZrO2. The molar ratio of TiO2 to Nb2O5 is in the range of 1:1 to 1:2. The optical glass preform prepared by the present invention, which utilizes a layered feeding gradient melting process combined with air suspension cooling and staged annealing, has a refractive index of 1.79-1.98, a transmittance greater than 92%, and a thermal expansion coefficient of less than 5×10 at 350°C. ‑6 / ℃.

Description

Technical Field

[0001] The present invention relates to the technical field of optical glass preform and its manufacturing technology, in particular to an optical glass preform for automotive lenses with high light transmittance, heat resistance and high refraction achieved by improving structure and material components and a preparation method thereof. Background Art

[0002] Optical glass preform is the initial shape of glass, usually cylindrical or block-shaped. After heating, cutting, polishing and other processes, it can be made into the focusing lens in the car light, such as the key component in LED headlights or laser headlights.

[0003] With the improvement of people's living standards and the rapid development of the automobile industry in recent years, consumers are particularly concerned about the various performances of automobiles. However, there are still many problems with existing automobile headlight lenses.

[0004] Lanthanide glass, as the material for optical glass preform rods of automotive lenses, once occupied an important position in high-performance car lights. It has a high refractive index, can focus light more efficiently, improve the illumination distance and brightness, has a strong focusing ability, and can significantly reduce the thickness of the lens; high Abbe number can reduce rainbow dispersion and ensure lighting clarity; good chemical stability, acid and alkali corrosion resistance, and is not easy to age when exposed to humid or salt spray environments for a long time; however, its heat resistance is poor and it can only withstand high temperatures above 300°C for a short period of time; poor mechanical properties, high brittleness, easy to crack during processing, and easily broken by stone impact, requiring additional coating or covering protective layer; and the manufacturing process is prone to streaks and bubbles, and crystallization will lead to a decrease in light transmittance.

[0005] Borosilicate glass is popular for its excellent heat resistance, strong thermal shock resistance, chemical stability, high mechanical strength, and readily available raw materials. However, its disadvantages are also significant. Borosilicate glass has a low refractive index and weak light-gathering ability, making it unsuitable for making ultra-thin lenses. While its dispersion is low, its low refractive index still results in slight dispersion in the short-wavelength (blue) region, affecting the purity of the laser headlight spot.

[0006] Chalcogenide glass, a class of infrared optical materials primarily composed of sulfur, selenium, and tellurium, has recently shown promise in automotive LiDAR and infrared thermal imaging lenses due to its uniquely wide infrared transmission range and tunable refractive index. However, its susceptibility to oxidation and insufficient light transmittance have limited its application in automotive lenses.

[0007] Further research is needed to obtain automotive lenses with high refractive index, high transmittance, and high temperature resistance while achieving low-cost large-scale manufacturing. Summary of the Invention

[0008] In order to meet the requirements of automotive lenses having high refractive index, high transmittance and high temperature resistance, the inventors of the present invention accidentally discovered during the research process that by replacing rare earths with a TiO2-Nb2O5 system and combining it with ZrO2 nanocrystals, the heat resistance of the material can be enhanced. In addition, gradient melting combined with gas suspension cooling technology is used to integrate the formation of optical glass preforms with high refractive index, high transmittance and high temperature resistance.

[0009] In order to solve the above technical problems and achieve multiple technical effects at the same time, the present invention is implemented through the following technical solutions:

[0010] In a first aspect, the present invention provides a high-transmittance, heat-resistant, and high-refractive optical glass preform for automotive lenses, wherein the optical glass preform comprises the following components in terms of molar percentage:

[0011] SiO2 40~50%,

[0012] B2O3 10~15%,

[0013] TiO2 5~10%,

[0014] Nb2O5 5~10%,

[0015] ZnO 3~8%,

[0016] Al2O3 2~5%,

[0017] CeO2 0.1~0.5%,

[0018] ZrO2 1~3%.

[0019] Furthermore, the molar ratio of TiO2 to Nb2O5 ranges from 1:1 to 1:2. Within this ratio range, TiO2 and Nb2O5 have a higher refractive index, which can save costs when finally made into automotive lenses, while also meeting the requirements of lightweight electric vehicles.

[0020] When the molar ratio of TiO2 to Nb2O5 is within the range of 1:1 to 1:2, the high concentration of Nb2O5 during the melt preparation process can change the crystal structure of TiO2 without affecting the transmittance of the optical glass preform. When the amount of Nb2O5 added is below the minimum value, the effect on increasing the refractive index is too small; when the amount of Nb2O5 added is above the maximum value, the transmittance of the optical glass preform is affected.

[0021] The present invention achieves a high refractive index while replacing rare earth elements through the synergistic effect of TiO2 and Nb2O5. Furthermore, the introduction of ZrO2 nanocrystals improves heat resistance to 350°C without affecting light transmittance.

[0022] The high-transmittance, heat-resistant and high-refractive automotive lens optical glass preform of the present invention has a refractive index of 1.79 to 1.98, a light transmittance greater than or equal to 92%, and a thermal expansion coefficient of less than 5×10 at 350°C. -6 / ℃. Preferably, the refractive index is 1.85-1.98, the transmittance is greater than or equal to 93%, and the thermal expansion coefficient at 350℃ is less than 4.6×10 -6 / ℃.

[0023] The dispersion coefficient of the high-transmittance, heat-resistant and high-refractive automobile lens optical glass preform of the present invention is 55-75, preferably, the dispersion coefficient is 60-75.

[0024] To further enhance the refractive index and light transmittance of an automotive lens optical glass preform, the present invention comprises a core layer and a cladding layer, the cladding layer and the core layer being laminated together. The core layer contains ≥15% TiO2+Nb2O5, preferably ≥16%, more preferably ≥17%, even more preferably ≥18%, and even more preferably ≥19%. Higher TiO2 and Nb2O5 contents in the core layer improve both the refractive index and high-temperature resistance. Furthermore, TiO2 absorbs ultraviolet light, preventing aging of automotive lenses.

[0025] The coating layer has a SiO2+B2O3 content of 50% or greater, preferably 51% or greater, more preferably 52% or greater, even more preferably 53% or greater, further preferably 55% or greater, and even more preferably 55% or greater. The SiO2 and B2O3 contents within these ranges can reduce rainbow dispersion and ensure the light transmittance and clarity of the automotive lens.

[0026] Furthermore, one or more oxides of the above-mentioned metal elements are partially or completely replaced with fluorides, and the F content is 0 to 1.8%. This can greatly improve the dispersibility and make the obtained preform rod more transparent. If the content exceeds this range, it will be difficult to form glass with uniform texture during the melting process, and it will affect the refractive index, resulting in a decrease in the refractive index.

[0027] In a second aspect, the present invention further provides a method for preparing a high-transmittance, heat-resistant, and high-refractive automotive lens optical glass preform, the preparation method comprising the following steps:

[0028] S1: Add TiO2, Nb2O5, ZrO2, ZnO, Al2O3, and CeO2 into a melting crucible, heat the melting crucible to a temperature of 1500-1700°C, then add SiO2 and B2O3, and apply 20-40kHz ultrasonic waves and electromagnetic stirring with a magnetic field strength of 0.5-1T during the melting process;

[0029] S2: dropping the molten liquid into an inert gas suspension device and cooling it to 600-700°C at a rate of 50-100°C / min;

[0030] S3: Maintain at 600-700°C for 1-3 hours, then raise the temperature to 700-800°C and maintain for 0.5-1.5 hours.

[0031] Furthermore, in step S1, the ultrasonic wave and the electromagnetic stirring are synchronously applied for a time greater than or equal to 30 minutes, which can better eliminate bubbles, reduce or avoid the generation of streaks, and thereby improve the light transmittance of the optical glass preform and the thermal expansion coefficient.

[0032] In step S1 of the present invention, raw materials are added in layers, and raw materials with high melting points are first added into the melting crucible for smelting, and then raw materials with low melting points are added, so as to better reduce component segregation.

[0033] In addition, ultrasonic oscillation combined with electromagnetic stirring is used to avoid the introduction of bubbles into the optical glass preform rod, while also avoiding the generation of streaks, requiring shorter melting time and lower costs.

[0034] In step S2 of the present invention, a gas suspension cooling device is used to avoid uneven stress caused by mold contact, and the cooling rate is controlled at 50-100° C. / min to prevent microcracks.

[0035] The step S3 of the present invention is divided into two stages of temperature annealing, and the annealing temperature of the second stage is slightly increased, which can promote the uniform precipitation of ZrO2 nanocrystals and enhance heat resistance.

[0036] The inert gas of the present invention may be a gas that does not react with the melt, and examples thereof include nitrogen, argon, helium, and the like.

[0037] In a third aspect, the present invention also provides an application of a high-transmittance, heat-resistant, and high-refractive optical glass preform for automotive lenses, wherein the optical glass preform is used as a raw material for manufacturing lenses for automotive LED or laser headlights.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] The automotive lens optical glass preform provided by the present invention can achieve a refractive index of 1.79 to 1.98, a light transmittance greater than or equal to 92%, and a thermal expansion coefficient of less than 5×10 at 350°C. -6 / ℃. DETAILED DESCRIPTION

[0040] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0041] The test method for the refractive index and dispersion coefficient of the optical glass preform described in the present invention refers to the standard GB / T7962.1-2010.

[0042] The test method for the light transmittance of the optical glass preform of the present invention refers to the standard GB / T 7962.5-2010.

[0043] The test method for the thermal expansion coefficient of the optical glass preform described in the present invention refers to the standard GB / T 7962.12-2010.

[0044] Example 1

[0045] 0.8 mol TiO2, 0.8 mol Nb2O5, 0.2 mol ZrO2, 0.5 mol ZnO, 0.3 mol Al2O3, and 0.03 mol CeO2 were added to a platinum crucible and heated to 1600°C for melting. 4.5 mol SiO2 and 1.2 mol B2O3 were then added. During the melting process, 30 kHz ultrasonic waves and electromagnetic stirring with a magnetic field strength of 0.8 T were used for 40 minutes. The molten liquid was then dropped into a nitrogen suspension environment and cooled at a rate of 80°C / min to 650°C, held for 2 hours, then heated to 750°C, held for 1 hour, and then cooled to room temperature at a rate of 80°C / min to obtain an optical glass preform A1.

[0046] The optical glass preform A1 obtained by the test has a refractive index of 1.89, an Abbe number of 69, a transmittance of 96%, and a thermal expansion coefficient of 1×10 at 350°C. -6 / ℃.

[0047] Example 2

[0048] Same as Example 1, except that 0.8 mol TiO2 and 1.5 mol Nb2O5 were added to the platinum crucible.

[0049] The optical glass preform obtained by the test has a refractive index of 1.97, an Abbe number of 72, a transmittance of 96%, and a thermal expansion coefficient of 1.4×10 at 350°C. -6 / ℃.

[0050] Example 3

[0051] Same as Example 1, except that 0.7 mol TiO2 and 0.7 mol Nb2O5 were added into the platinum crucible.

[0052] The optical glass preform obtained by the test has a refractive index of 1.80, an Abbe number of 68, a transmittance of 95%, and a thermal expansion coefficient of 2.1×10 at 350°C. -6 / ℃.

[0053] Example 4

[0054] Same as Example 1, except that 4.2 mol SiO2 and 1 mol B2O3 were added to the platinum crucible.

[0055] The optical glass preform obtained by the test has a refractive index of 1.86, an Abbe number of 68, a transmittance of 95%, and a thermal expansion coefficient of 1.5×10 at 350°C. -6 / ℃.

[0056] Example 5

[0057] The same as Example 1, except that: 30kHz ultrasonic waves and electromagnetic stirring with a magnetic field strength of 0.8T were used for 10 minutes during the smelting process.

[0058] The optical glass preform obtained by the test has a refractive index of 1.87, an Abbe number of 66, a transmittance of 94%, and a thermal expansion coefficient of 3.2×10 at 350°C. -6 / ℃.

[0059] Example 6

[0060] The same as Example 1, except that the molten liquid is dropped into a nitrogen suspension environment and cooled to 650° C. at a rate of 50° C. / min.

[0061] The optical glass preform obtained by the test has a refractive index of 1.90, an Abbe number of 68, a transmittance of 96%, and a thermal expansion coefficient of 9×10 at 350°C. -7 / ℃.

[0062] Example 7

[0063] The same as Example 1, except that: instead of adding 0.3 mol of Al2O3 into the platinum crucible, 0.2 mol of Al2O3 and 0.1 mol of aluminum fluoride are added.

[0064] The optical glass preform obtained by the test has a refractive index of 1.97, an Abbe number of 71, a transmittance of 97%, and a thermal expansion coefficient of 9×10 at 350°C. -7 / ℃.

[0065] Example 8

[0066] Same as Example 1, except that 0.5 mol TiO2 and 0.8 mol Nb2O5 were added into the platinum crucible.

[0067] The optical glass preform obtained by the test has a refractive index of 1.79, an Abbe number of 61, a transmittance of 98%, and a thermal expansion coefficient of 1.3×10 at 350°C. -7 / ℃.

[0068] Comparative Example 1

[0069] Same as Example 1, except that 0.8 mol TiO2 and 2 mol Nb2O5 were added into the platinum crucible.

[0070] The test results show that the refractive index of the optical glass preform is 1.98, the dispersion coefficient is 72, the transmittance is 90%, and the thermal expansion coefficient at 350°C is 1.2×10- 7 / ℃.

[0071] Comparative Example 2

[0072] 0.8 mol TiO2, 0.8 mol Nb2O5, 0.2 mol ZrO2, 0.5 mol ZnO, 0.3 mol Al2O3, 0.03 mol CeO2, 4.5 mol SiO2, and 1.2 mol B2O3 were added to a platinum crucible and heated to 1600°C for melting. During the melting process, 30 kHz ultrasonic waves and electromagnetic stirring with a magnetic field strength of 0.8 T were used for 40 minutes. The molten liquid was then dropped into a nitrogen suspension environment and cooled at a rate of 80°C / min to 650°C, held for 2 hours, then heated to 750°C, held for 1 hour, and then cooled to room temperature at a rate of 80°C / min to obtain an optical glass preform.

[0073] The optical glass preform obtained by the test has a refractive index of 1.87, an Abbe number of 69, a transmittance of 91%, and a thermal expansion coefficient of 7×10 at 350°C. -6 / ℃.

[0074] Comparative Example 3

[0075] 0.8 mol TiO2, 0.8 mol Nb2O5, 0.2 mol ZrO2, 0.5 mol ZnO, 0.3 mol Al2O3, and 0.03 mol CeO2 were added to a platinum crucible and heated to 1600°C for melting. 4.5 mol SiO2 and 1.2 mol B2O3 were then added. The melt was stirred 2-3 times during the melting process. The melt was then poured into a preheated mold and cooled to 650°C at a rate of 80°C / min. The glass was then annealed at 30-700°C.

[0076] The optical glass preform obtained by the test has a refractive index of 1.70, an Abbe number of 65, a transmittance of 90%, and a thermal expansion coefficient of 7.5×10 at 350°C. -6 / ℃.

[0077] The performance data of the optical glass preforms prepared in Examples 1 to 8 and Comparative Examples 1 to 4 are shown in Table 1.

[0078] Table 1 Performance data of optical glass preforms prepared in Examples and Comparative Examples

[0079]

[0080]

[0081] From the data in Table 1 we can see that:

[0082] Comparing Example 1 and Comparative Example 1, when Nb2O5 is added in excess and the addition ratio of TiO2 to Nb2O5 is not within the range of 1:1 to 1:2, the transmittance of the obtained optical glass preform is low. This is because Nb2O5 has no effect or little effect on the reconstruction of the titanium dioxide structure during the melting preparation process.

[0083] Comparing Example 1 with Comparative Example 2, melting the raw materials in stages, first melting the high melting point raw materials and then melting the low melting point raw materials, can reduce component segregation and improve the transmittance and thermal expansion coefficient of the optical glass preform.

[0084] Comparing Example 1 and Comparative Example 3, the electromagnetic stirring combined with ultrasonic oscillation is used simultaneously to improve the melting efficiency while effectively eliminating the fuzziness caused by stirring and avoiding the generation of stripes on the optical glass preform rod. In addition, the air suspension cooling technology is used to improve the transmittance, reduce thermal stress and lower the thermal expansion coefficient, and also improve the refractive index and dispersion coefficient.

[0085] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can, without departing from the scope of the technical solution of the present invention, make some changes or modifications to equivalent embodiments using the technical contents disclosed above. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A high-transmittance, heat-resistant, and high-refractive optical glass preform for automotive lenses, characterized by: The optical glass preform comprises the following components in molar percentage: SiO2 49.83-56.04%, B2O3 10-15%, TiO2 6.23-10%, Nb2O5 8.61-16.61%, ZnO 3-8%, Al2O3 2-5%, CeO2 0.1-0.5%, ZrO2 1-3%, Wherein, the molar ratio of TiO2 to Nb2O5 is in the range of 1:1 to 1:2, The optical glass preform has a refractive index of 1.79 to 1.98, a light transmittance greater than 92%, and a thermal expansion coefficient less than 5×10 at 350°C. -6 / ℃; The high-transmittance, heat-resistant and high-refractive automotive lens optical glass preform is prepared by a preparation method comprising the following steps: S1: Add TiO2, Nb2O5, ZrO2, ZnO, Al2O3, and CeO2 into a melting crucible, heat the melting crucible to a temperature of 1500-1700°C, then add SiO2 and B2O3, and apply 20-40kHz ultrasonic waves and electromagnetic stirring with a magnetic field strength of 0.5-1T during the melting process; S2: dropping the molten liquid into an inert gas suspension device and cooling it to 600-700°C at a rate of 50-100°C / min; S3: Maintain at 600-700°C for 1-3 hours, then raise the temperature to 700-800°C and maintain for 0.5-1.5 hours.

2. The high-transmittance, heat-resistant, and high-refractive automotive lens optical glass preform according to claim 1, characterized in that: The dispersion coefficient of the optical glass preform is 55-75.

3. The high-transmittance, heat-resistant, and high-refractive optical glass preform for automotive lenses according to claim 1, characterized in that: The ZrO2 is nanocrystalline.

4. The high-transmittance, heat-resistant, and high-refractive optical glass preform for automotive lenses according to claim 1, characterized in that: The optical glass preform comprises a core layer and a cladding layer, and the core layer and the cladding layer are bonded together.

5. The high-transmittance, heat-resistant, and high-refractive optical glass preform for automotive lenses according to claim 4, characterized in that: The sum of the TiO2 and Nb2O5 contents in the core layer is ≥15%.

6. The high-transmittance, heat-resistant, and high-refractive optical glass preform for automotive lenses according to claim 4, characterized in that: The sum of the SiO2 and B2O3 contents in the coating layer is ≥55%.

7. A method for preparing a high-transmittance, heat-resistant, and high-refractive automotive lens optical glass preform according to any one of claims 1 to 6, characterized in that: The preparation method comprises the following steps: S1: Add TiO2, Nb2O5, ZrO2, ZnO, Al2O3, and CeO2 into a melting crucible, heat the melting crucible to a temperature of 1500-1700°C, then add SiO2 and B2O3, and apply 20-40kHz ultrasonic waves and electromagnetic stirring with a magnetic field strength of 0.5-1T during the melting process; S2: dropping the molten liquid into an inert gas suspension device and cooling it to 600-700°C at a rate of 50-100°C / min; S3: Maintain at 600-700°C for 1-3 hours, then raise the temperature to 700-800°C and maintain for 0.5-1.5 hours.

8. The method for preparing a high-transmittance, heat-resistant, and high-refractive automotive lens optical glass preform according to claim 7, characterized in that: In step S1, the ultrasonic wave and the electromagnetic stirring act synchronously for a time greater than or equal to 30 minutes.

9. The method for preparing a high-transmittance, heat-resistant, and high-refractive optical glass preform for automotive lenses according to claim 7, wherein: The optical glass preform includes a core layer and a cladding layer. According to step S1, raw materials are melted into a core layer melt and a cladding layer melt respectively. Then, according to step S2, the core layer melt is first dropped into an inert gas suspension device, and then the cladding layer melt is dropped into the inert gas suspension device, and then cooled to 600-700°C at a rate of 50-100°C / min.

10. An application of the high-transmittance, heat-resistant, and high-refractive optical glass preform for automotive lenses according to any one of claims 1 to 6, characterized in that: The optical glass preform is used as a raw material to manufacture lenses of LED or laser headlights of automobiles.

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