Automobile lens optical glass preform and preparation method thereof

Abstract

The invention relates to an optical glass preform for an automobile lens and a preparation method thereof, the optical glass preform comprises the following components in molar percentage: 40-50% of SiO2, 10-15% of B2O3, 5-10% of TiO2, 5-10% of Nb2O5, 3-8% of ZnO, 2-5% of Al2O3, 0.1-0.5% of CeO2 and 1-3% of ZrO2, and the molar ratio of TiO2 to Nb2O5 ranges from 1: 1 to 1: 2. The prefabricated refractive index of the optical glass prepared by combining layered feeding and gradient smelting with the air suspension cooling and staged annealing process is 1.79-1.98, the light transmittance is greater than 92%, and the thermal expansion coefficient at 350 DEG C is less than 5 * 10 <-6 > / DEG C.

Description

Technical Field

[0001] The invention relates to the technical field of optical glass preform and its manufacturing, and 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 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 irradiation distance and brightness, has a strong light-gathering 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 easy to break when hit by stones, requiring additional coating or covering protective layer; and streaks and bubbles are prone to occur during the manufacturing process, and crystallization will lead to a decrease in light transmittance.

[0005] Borosilicate glass has excellent heat resistance, strong thermal shock resistance, chemical stability, high mechanical strength, and easy-to-obtain raw materials. However, its disadvantages are also obvious. Borosilicate glass has a low refractive index and weak light-gathering ability, and is not suitable for making ultra-thin lenses. Its dispersion is low, but the low refractive index may still cause slight dispersion in the short wavelength (blue light) region, affecting the purity of the laser headlight spot.

[0006] Chalcogenide glass is a type of infrared optical material with sulfur, selenium and tellurium as its main components. In recent years, it has shown potential in automotive laser radar and infrared thermal imaging lenses due to its unique wide infrared transmission range and adjustable refractive index. However, it is easily oxidized and has insufficient light transmittance, so it is rarely used in the field of 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 light transmittance and high temperature resistance, the inventor of the present invention accidentally discovered during the research that by using TiO2 -Nb 2 O 5 The system replaces rare earths and combines ZrO 2 Nanocrystals can enhance the heat resistance of the material. In addition, the gradient melting combined with the gas suspension cooling technology is used to integrally form an optical glass preform with high refractive index, high light 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 realized through the following technical solutions:

[0010] In a first aspect, the present invention provides a high light-transmitting, heat-resistant and high-refractive automotive lens optical glass preform, and the optical glass preform comprises the following components in terms of mole percentage:

[0011] SiO 2 40-50%,

[0012] B 2 O 3 10-15%,

[0013] TiO 2 5-10%,

[0014] Nb 2 O 5 5-10%,

[0015] ZnO 3-8%,

[0016] Al 2 O 3 2-5%,

[0017] CeO 2 0.1-0.5%,

[0018] ZrO 2 1-3%.

[0019] Furthermore, the molar ratio of TiO 2 to Nb 2 O 5 ranges from 1:1 to 1:2. When the molar ratio of TiO 2 to Nb 2 O 5 is within this ratio range, it has a higher refractive index. When finally making an automotive lens, it can save costs and also meet the requirements of lightweight of electric vehicles.

[0020] When the molar ratio of TiO 2 to Nb 2 O 5 is within the range of 1:1 to 1:2, during the melting preparation process, high-concentration Nb2 O 5 can cause the crystal structure of TiO 2 to change without affecting the light transmittance of the optical glass preform. When the addition amount of Nb 2 O 5 is lower than the minimum value, the effect of improving the refractive index is too small; when the addition amount of Nb 2 O 5 is higher than the maximum value, it will affect the light transmittance of the optical glass preform.

[0021] Through the synergistic effect of TiO 2 and Nb 2 O 5 , while replacing rare earth elements, high refractive index can also be achieved. In addition, by introducing ZrO 2 nanocrystals, the high heat resistance is increased to 350 °C without affecting the light transmittance.

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

[0023] The Abbe number of the high light-transmitting, heat-resistant and high-refractive automotive lens optical glass preform described in the present invention is 55 - 75, preferably, the Abbe number is 60 - 75.

[0024] In order to further improve the refractive index and light transmittance of the automotive lens optical glass preform, the automotive lens optical glass preform described in the present invention includes a core layer and a cladding layer. The cladding layer and the core layer are bonded together. The content of TiO 2 + Nb 2 O 5 in the core layer is ≥ 15%, preferably the content of TiO 2 + Nb 2 O 5 is ≥ 16%, more preferably, the content of TiO 2 + Nb 2 O 5 is ≥ 17%, even more preferably, the content of TiO 2 + Nb 2 O 5 is ≥ 18%, further preferably, the content of TiO 2 + Nb 2 O 5 is ≥ 19%. The TiO 2 and Nb 2 O5 The higher the content, the more beneficial it is to improve the refractive index, and at the same time, it can also enhance the high-temperature resistance performance. In addition, TiO 2 can absorb ultraviolet rays and prevent the aging of automotive lenses.

[0025] In the coating layer, SiO 2 +B 2 O 3 content ≥ 5 0%, preferably, SiO 2 +B 2 O 3 content ≥ 51%, more preferably, SiO 2 +B 2 O 3 content ≥ 52%, even more preferably, SiO 2 +B 2 O 3 content ≥ 53%, further preferably, SiO 2 +B 2 O 3 content ≥ 55%, further more preferably, SiO 2 +B 2 O 3 content ≥ 55%. The content of SiO 2 and B 2 O 3 within the above range can reduce the phenomenon of rainbow dispersion and ensure the light transmittance and clarity of automotive lenses.

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

[0027] In the second aspect, the present invention also provides a method for preparing a high-light-transmittance, heat-resistant, and high-refractive-index optical glass preform for automotive lenses. The preparation method includes the following steps:

[0028] S1: Add TiO 2 , Nb 2 O 5 , ZrO 2 , ZnO, Al 2 O 3 , CeO 2 into the melting crucible, heat the melting crucible to a temperature of 1500 - 1700 °C, and then add SiO 2 , B 2 O 3, ultrasonic waves of 20 - 40 kHz and electromagnetic stirring with a magnetic field intensity of 0.5 - 1 T are applied during the melting process;

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

[0030] S3: Hold at 600 - 700 °C for 1 - 3 hours, then heat up to 700 - 800 °C and hold for 0.5 - 1.5 hours.

[0031] Furthermore, in step S1, the time when the ultrasonic waves and the electromagnetic stirring act synchronously is greater than or equal to 30 minutes, which can better eliminate bubbles, reduce or avoid the generation of streaks, and thus improve the light transmittance and the thermal expansion coefficient of the optical glass preform.

[0032] In step S1 of the present invention, the raw materials are layered and input. The raw materials with high melting points are first put into the melting crucible for melting, and then the raw materials with low melting points are added, which can better reduce component segregation.

[0033] In addition, by using the method of ultrasonic oscillation combined with electromagnetic stirring, bubbles are avoided from being introduced into the optical glass preform, and streaks can also be avoided. The required melting time is shorter and the cost is lower.

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

[0035] In step S3 of the present invention, annealing is carried out at two-stage temperatures. The annealing temperature of the second stage is slightly increased, which can promote the uniform precipitation of ZrO 2 nanocrystals and enhance the heat resistance.

[0036] The inert gas in the present invention can be a gas that does not react with the molten liquid, such as nitrogen, argon, helium, etc.

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

[0038] Compared with the prior art, the beneficial effects of the present invention are as follows:

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

[0040] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts fall 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 described in the present invention refers to the standard GB / T 7962.5-2010.

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

[0044] Example 1

[0045] Add 0.8 mol of TiO 2 , 0.8 mol of Nb 2 O 5 , 0.2 mol of ZrO 2 , 0.5 mol of ZnO, 0.3 mol of Al 2 O 3 and 0.03 mol of CeO 2 to the platinum crucible, heat the platinum crucible to 1600 °C to start melting, and then add 4.5 mol of SiO 2 and 1.2 mol of B 2 O 3 . During the melting process, use 30 kHz ultrasonic waves and electromagnetic stirring with a magnetic field strength of 0.8 T for 40 minutes. Subsequently, drop the molten liquid into a nitrogen suspension environment and cool it to 650 °C at a rate of 80 °C / min, hold for 2 hours, heat up to 750 °C and hold for 1 hour, and then cool it to room temperature at a rate of 80 °C / min to obtain the optical glass preform A1.

[0046] The refractive index of the obtained optical glass preform A1 is tested to be 1.89, the dispersion coefficient is 69, the light transmittance is 96%, and the coefficient of thermal expansion at 350 °C is 1×10 -6 / °C.

[0047] Example 2

[0048] Same as Example 1, the difference is that: add 0.8 mol of TiO 2 , 1.5 mol of Nb 2 O 5 to the platinum crucible.

[0049] The refractive index of the optical glass preform obtained by testing is 1.97, the dispersion coefficient is 72, the light transmittance is 96%, and the thermal expansion coefficient at 350 °C is 1.4×10 -6 / °C.

[0050] Example 3

[0051] Same as Example 1, the difference is that: 0.7 mol of TiO is added to the platinum crucible 2 、0.7 mol of Nb 2 O 5 .

[0052] The refractive index of the optical glass preform obtained by testing is 1.80, the dispersion coefficient is 68, the light transmittance is 95%, and the thermal expansion coefficient at 350 °C is 2.1×10 -6 / °C.

[0053] Example 4

[0054] Same as Example 1, the difference is that: 4.2 mol of SiO is added to the platinum crucible 2 and 1 mol of B 2 O 3 .

[0055] The refractive index of the optical glass preform obtained by testing is 1.86, the dispersion coefficient is 68, the light transmittance is 95%, and the thermal expansion coefficient at 350 °C is 1.5×10 -6 / °C.

[0056] Example 5

[0057] Same as Example 1, the difference is that: during the melting process, 30 kHz ultrasonic waves and electromagnetic stirring with a magnetic field strength of 0.8 T are used for 10 minutes.

[0058] The refractive index of the optical glass preform obtained by testing is 1.87, the dispersion coefficient is 66, the light transmittance is 94%, and the thermal expansion coefficient at 350 °C is 3.2×10 -6 / °C.

[0059] Example 6

[0060] Same as Example 1, the difference is 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 refractive index of the optical glass preform obtained by testing is 1.90, the dispersion coefficient is 68, the light transmittance is 96%, and the thermal expansion coefficient at 350 °C is 9×10 -7 / °C.

[0062] Example 7

[0063] Same as Example 1, the difference is that: 0.3 mol of Al is added to the platinum crucible 2 O 3 is changed to add 0.2 mol of Al 2 O 3 and 0.1 mol of aluminum fluoride.

[0064] The refractive index of the optical glass preform obtained by testing is 1.97, the dispersion coefficient is 71, the light transmittance is 97%, and the thermal expansion coefficient at 350 °C is 9×10 -7 / °C.

[0065] Example 8

[0066] Same as Example 1, the difference is that: 0.5 mol of TiO is added to the platinum crucible 2 , 0.8 mol of Nb 2 O 5 .

[0067] The refractive index of the optical glass preform obtained by testing is 1.79, the dispersion coefficient is 61, the light transmittance is 98%, and the thermal expansion coefficient at 350 °C is 1.3×10 -7 / °C.

[0068] Comparative Example 1

[0069] Same as Example 1, the difference is that: 0.8 mol of TiO is added to the platinum crucible 2 , 2 mol of Nb 2 O 5 .

[0070] The refractive index of the optical glass preform obtained by testing is 1.98, the dispersion coefficient is 72, the light transmittance is 90%, and the thermal expansion coefficient at 350 °C is 1.2×10- 7 / °C.

[0071] Comparative Example 2

[0072] Add 0.8 mol of TiO to the platinum crucible 2 , 0.8 mol of Nb 2 O 5 , 0.2 mol of ZrO 2 , 0.5 mol of ZnO, 0.3 mol of Al 2 O 3 , 0.03 mol of CeO 2 , 4.5 mol of SiO 2 and 1.2 mol of B 2 O 3, Heat the platinum crucible to 1600 °C and start melting. During the melting process, use 30 kHz ultrasonic waves and electromagnetic stirring with a magnetic field strength of 0.8 T for 40 minutes. Subsequently, drop the molten liquid into a nitrogen suspension environment and cool it to 650 °C at a rate of 80 °C / min, hold for 2 hours, heat up to 750 °C and hold for 1 hour, and then cool it to room temperature at a rate of 80 °C / min to obtain an optical glass preform.

[0073] The refractive index of the obtained optical glass preform was measured to be 1.87, the dispersion coefficient was 69, the light transmittance was 91%, and the thermal expansion coefficient at 350 °C was 7×10 -6 / °C.

[0074] Comparative Example 3

[0075] Add 0.8 mol of TiO 2 , 0.8 mol of Nb 2 O 5 , 0.2 mol of ZrO 2 , 0.5 mol of ZnO, 0.3 mol of Al 2 O 3 and 0.03 mol of CeO 2 to the platinum crucible, heat the platinum crucible to 1600 °C and start melting, then add 4.5 mol of SiO 2 and 1.2 mol of B 2 O 3 . Stir the molten material 2 - 3 times during the melting process. Subsequently, pour the molten material into a preheated mold and cool it to 650 °C at a rate of 80 °C / min, and anneal the glass at 30 - 700 °C.

[0076] The refractive index of the obtained optical glass preform was measured to be 1.70, the dispersion coefficient was 65, the light transmittance was 90%, and the thermal expansion coefficient at 350 °C was 7.5×10 -6 / °C.

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

[0078] Table 1 Performance data of optical glass preforms prepared in examples and comparative examples

[0079]

[0080]

[0081] As can be seen from the data in Table 1:

[0082] Comparing Example 1 and Comparative Example 1, when Nb 2 O 5Excessive addition of 2 and Nb 2 O 5 The addition ratio is not within the range of 1:1 to 1:2, and the light transmittance of the prepared optical glass preform is relatively low. This is because during the melting preparation process, Nb 2 O 5 has no effect or a small effect on the structural reconstruction of titanium dioxide.

[0083] Comparing Example 1 and Comparative Example 2, by melting the raw materials in segments, melting the high-melting-point raw materials first and then the low-melting-point raw materials, component segregation can be reduced, and the light transmittance and thermal expansion coefficient of the optical glass preform can be improved.

[0084] Comparing Example 1 and Comparative Example 3, by using electromagnetic stirring combined with ultrasonic vibration simultaneously, while improving the melting efficiency, it can effectively eliminate the air bubbles generated by stirring and avoid the generation of stripes in the optical glass preform. In addition, by using the gas suspension cooling technology, the light transmittance can be improved, the thermal stress can be reduced, the thermal expansion coefficient can be decreased, and the refractive index and dispersion coefficient can also be improved.

[0085] The above are only the preferred embodiments of the present invention, and do not impose any form of limitation on the present invention. Although the present invention has been disclosed as above with the preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to the above-disclosed technical content to form equivalent embodiments with equivalent changes, but as long as the technical content of the present invention is not departed from, any brief modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A high light transmittance, heat resistant and high refractive automotive lens optical glass preform, characterized by: The optical glass preform comprises the following components in terms of molar percentage: SiO240~50%, B2O310~15%, TiO25~10%, Nb2O55~10%, ZnO 3~8%, Al2O32~5%, CeO2 0.1~0.5%, ZrO21~3%, 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 of more than 92%, and a thermal expansion coefficient of less than 5×10 -6 / ℃.

2. The high light 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 light transmittance, heat resistant and high refractive automotive lens optical glass preform according to claim 1, characterized in that: The ZrO2 is nanocrystalline.

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

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

7. A method for preparing the 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, 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 automotive lens optical glass preform according to claim 7, characterized in that: The optical glass preform comprises a core layer and a cladding layer. According to step S1, raw materials are melted into a core layer molten liquid and a cladding layer molten liquid respectively. According to step S2, the core layer molten liquid is first dripped onto an inert gas suspension device, and then the cladding layer molten liquid is dripped onto an inert gas suspension device, and then cooled to 600-700°C at a rate of 50-100°C / min.

10. An application of 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 optical glass preform is used as a raw material to manufacture lenses of LED or laser headlights of automobiles.

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