Low-absorbing high-transmission glass and method of forming same and vehicle glazing

Abstract

This invention provides a low-absorption, high-transmittance glass, its forming method, and an automotive window glass. The forming method includes placing a glass sheet in a heating furnace for heating treatment and then pressing it into shape. The heating furnace includes a preheating section, a heating section, and a constant-temperature gradient section connected in sequence. The inlet temperature of the preheating section is 548-596℃, and the outlet temperature is 571-631℃, with the outlet temperature higher than the inlet temperature. The inlet temperature of the heating section is 595-646℃, and the outlet temperature is 628-673℃, with the outlet temperature higher than the inlet temperature. The temperature of the constant-temperature gradient section is 628-674℃. The inlet temperature of the heating section is greater than or equal to the outlet temperature of the preheating section, and the difference between the inlet temperature of the constant-temperature gradient section and the outlet temperature of the heating section is ≥-3℃. The low-absorption, high-transmittance glass can meet the optical transmittance requirements of optical sensors and can be used in the manufacture of functionally integrated glass.

Description

Technical Field

[0001] This invention relates to the field of automotive glass manufacturing technology, and in particular to a low-absorption, high-transparency glass, its forming method, and automotive window glass. Background Technology

[0002] Automotive glass, especially windshields, generally uses automotive-grade glass sheets produced using the float glass process. Automotive-grade glass sheets include: clear glass (C), green glass (G), solar-absorbing green glass (SG), and super-solar-absorbing green glass (SD), etc.

[0003] Currently, automotive glass, especially windshields, integrates an increasing number of optical sensor components, such as LiDAR and infrared cameras, in its raised areas. These optical sensors place increasingly higher demands on the windshield, requiring maximum optical transmittance in the corresponding near-infrared band, such as 800-1600nm. Existing automotive glass substrates cannot meet these requirements, necessitating glass substrates with low absorption and high transmittance in the corresponding band. The forming parameters of such glass substrates with low absorption and high transmittance in the corresponding band differ from those of existing automotive glass substrates, requiring a forming method specifically designed for these glass substrates. Summary of the Invention

[0004] To address the aforementioned problems, the present invention aims to provide a low-absorption, high-transmittance glass, its forming method, and an automotive window glass. This low-absorption, high-transmittance glass has a low forming temperature, low absorption, and high light transmittance, meeting the optical transmittance requirements of optical sensors and enabling its use in the manufacture of functionally integrated glass.

[0005] To achieve the above objectives, the present invention provides a method for forming low-absorption, high-transmittance glass, the method comprising:

[0006] The raw glass sheet is placed in a heating furnace for heating treatment, and then pressed into shape to obtain the low-absorption, high-transmittance glass. The heating furnace includes a preheating section, a heating section, and a constant-temperature gradient section connected in sequence. The inlet temperature of the preheating section is 548-596℃, and the outlet temperature of the preheating section is 571-631℃, with the outlet temperature of the preheating section being higher than the inlet temperature. The inlet temperature of the heating section is 595-646℃, and the outlet temperature of the heating section is 628-673℃, with the outlet temperature of the heating section being higher than the inlet temperature. The temperature of the constant-temperature gradient section is 628-674℃. The inlet temperature of the heating section is greater than or equal to the outlet temperature of the preheating section, and the difference between the inlet temperature of the constant-temperature gradient section and the outlet temperature of the heating section is ≥-3℃ (i.e., inlet temperature of the constant-temperature gradient section - outlet temperature of the heating section ≥-3℃).

[0007] In the above forming method, the preheating section is used for the first stage of heating the glass sheet, the heating section is used for the second stage of heating the glass sheet, and the constant temperature gradient section is used to keep the glass sheet warm and transfer it to subsequent processes. The preheating and heating sections can be roughly divided based on the softening temperature of the glass sheet. The temperature of the glass sheet in the preheating section is generally lower than its softening temperature, while the temperature of the glass sheet in the heating section is generally higher than its softening temperature. Therefore, the glass sheet begins to soften after entering the heating section. It is understood that in actual production, the heating temperature of the furnace is generally not equal to the glass's softening temperature. Therefore, the heating temperature of each section of the furnace can be adjusted accordingly based on the glass's softening temperature range, as long as the glass is heated in the preheating section but does not begin to soften, and begins to soften after entering the heating section.

[0008] In this invention, the softening temperature of the glass sheet refers to the temperature at which the glass begins to deform or soften under its own weight. For example, the softening temperature of low-absorption, high-transmittance glass sheets such as ultra-clear glass sheets is around 606℃. The softening temperature of glass is generally 100-120℃ lower than its softening point. The softening point refers to the temperature at which the glass begins to deform or soften under certain conditions. The softening point can be measured using the Littleten glass wire vertical elongation method, the process of which is as follows: heating and suspending with a density of 2.5 g / cm³. 3 The softening point is the temperature at which a glass fiber with a diameter of 0.55-0.75 mm and a length of 229 mm is stretched at a speed of 1 mm / min.

[0009] In the above molding method, the heating rate of the preheating section can be controlled to be 0.07℃ / s-5.4℃ / s.

[0010] In the above molding method, the heating rate of the heating section can be controlled to be 0.01℃ / s-4.0℃ / s.

[0011] In some specific implementations, the heating rate of the preheating section can be greater than or equal to the heating rate of the heating section. The temperature change range in the constant-temperature gradual transition section is small, and the heating rate is very small; the heating rate of the constant-temperature gradual transition section is generally less than that of the preheating section and the heating section.

[0012] In the above molding method, the heating method in each section (preheating section, heating section, constant temperature gradual change section) can be a common heating method such as uniform heating, variable speed heating, or step heating. The present invention does not have any special limitation on the heating method.

[0013] This invention divides the heating furnace into three main heating treatment sections according to function: a preheating section, a heating section, and a constant temperature gradual change section. Each section can be further divided according to the actual situation of the equipment (such as the position and number of heating components such as heating wires in the heating furnace). This invention does not have a special limitation on the number of further divisions of the preheating section, heating section, and constant temperature gradual change section, as long as the heating scheme of each section (such as heating temperature, heating rate, etc.) can be realized.

[0014] The molding method of the present invention will be further explained below using an example of a heating furnace with 9 heating zones:

[0015] In the above forming method, the heating furnace can specifically have nine heating zones. From the inlet end to the outlet end of the heating furnace, the heating zones are sequentially designated as Zone 1 to Zone 9. Zones 1 to 3 are preheating sections, Zones 4 to 7 are heating sections, and Zones 8 to 9 are constant temperature gradual change sections. From Zone 1 to Zone 9, the heating temperature gradually increases (overall, there is an upward trend, but it is not excluded that adjacent heating zones have similar temperatures, for example, the temperatures of Zones 7, 8, and 9 can be close). Each heating zone simultaneously heats the glass sheet from both above and below. The heating temperatures of Zones 1, 2, and 3 are 548-631℃, Zones 4, 5, and 6 are 595-657℃, and Zones 7, 8, and 9 are 628-674℃.

[0016] According to a specific embodiment of the present invention, the glass substrate applicable to the above-described forming method provided by the present invention is a low-absorption, high-transmittance glass substrate. Ordinary glass substrates have a high iron content (e.g., ordinary clear glass has an iron content of 700-900 ppm, ordinary green glass has an iron content of 5000 ppm, and absorptive green glass has an iron content of approximately 7000 ppm). The glass substrate applicable to the present invention has an even lower iron content, generally below 150 ppm, further below 130 ppm or 110 ppm, and even further below 90 ppm. The iron content refers to the weight content of iron oxide. The lower the iron content, the lower the absorption of the glass substrate.

[0017] Furthermore, the softening point of ordinary glass sheets is relatively high, around 725-730℃, while the softening point of the glass sheets applicable to this invention is relatively low, around 707-713℃. The annealing point of the glass sheets applicable to this invention is generally 540-550℃, meaning the softening point is about 28-32% (e.g., 30%) higher than the annealing point. The softening point of the glass sheets applicable to this invention is directly proportional to the annealing point; the higher the softening point, the higher the corresponding annealing point. In the above-described forming method of this invention, the heating temperature of the first zone can be higher than the annealing point of the glass sheet.

[0018] In the above forming method, the thickness of the glass sheet used is generally 1.6mm-6mm. Specifically, the glass sheet can be a 2.1mm thick glass sheet (2.1C glass sheet, specifically ultra-clear glass) used for the manufacture of windshields; or it can be a glass sheet with a thickness of less than 6mm used for the manufacture of corner window glass.

[0019] In the above forming method, the light absorption coefficient of the glass substrate for light with wavelengths of 800-1600 nm can be 0.04-0.2 cm⁻¹. -1 For example, 0.04cm -1 0.05cm -1 0.06cm -1 0.07cm -1 0.08cm -1 0.09cm -1 0.10cm -1 0.11cm -1 0.12cm -1 0.13cm -1 0.14cm -1 0.15cm -1 0.16cm -1 0.17cm -1 0.18cm -1 0.19cm -1 0.20cm -1 Specific values ​​and a range with any two of the above specific values ​​as endpoints. Further, the light absorption coefficient can be 0.04-0.1 cm⁻¹. -1 .

[0020] In this invention, the light absorption coefficient refers to the negative natural logarithm of the internal transmittance per centimeter of natural light passing through the glass substrate. When incident light is perpendicularly incident on the glass substrate, the light intensity is attenuated due to absorption by the glass substrate. The light absorption coefficient can be calculated by measuring the natural light transmittance of the glass substrate. Specifically, it can be calculated using the following formula:

[0021]

[0022] K is the light absorption coefficient of the glass substrate, l is the thickness of the glass substrate in the stacking direction; n is the refractive index of the glass substrate for a specific wavelength of laser light, and T is the transmittance of the glass substrate for a specific wavelength of laser light.

[0023] In some specific embodiments, the glass sheet used in this invention can be obtained through a float glass production process, such as an electronic-grade float glass production process.

[0024] The overall forming temperature (i.e., hot bending forming temperature, which is the heating temperature of the glass sheet in the furnace) in the forming method of the present invention is approximately in the range of 550-690°C, which is generally more than 10°C lower than the existing automotive glass forming temperature, more than 13°C lower than the existing automotive glass forming temperature, and even more than 15°C lower than the existing automotive glass forming temperature. The above forming temperature range is applicable to the heating and forming of glass sheets with a thickness of 1.6-6 mm.

[0025] In the above forming method, along the inlet to outlet of the heating furnace (i.e., along the transport direction of the glass sheet from inlet to outlet), the heating zones within the furnace are sequentially connected as Zone 1, Zone 2, Zone 3, Zone 4, Zone 5, Zone 6, Zone 7, Zone 8, and Zone 9. From Zone 1 to Zone 9, the heating temperature gradually increases. Zones 1, 2, and 3 can be referred to as the first three zones; Zones 4, 5, and 6 as the middle three zones; and Zones 7, 8, and 9 as the last three zones. The heating temperature gradually increases from Zone 1 to Zone 9 (generally an upward trend, but the possibility of adjacent heating zones having similar temperatures cannot be excluded). Specifically, from Zone 1 to Zone 7, the heating temperature gradually increases; Zone 8 has a similar heating temperature to Zone 7; and Zone 9 has the same or similar heating temperature to Zone 8.

[0026] According to a specific embodiment of the present invention, the heating temperatures of the first, second, and third zones are generally controlled to be 548-631℃, for example, specific values ​​such as 548℃, 550℃, 553℃, 560℃, 570℃, 580℃, 590℃, 600℃, 610℃, 620℃, 626℃, 630℃, and 631℃, as well as ranges with any two of the above specific values ​​as endpoints. Further, the heating temperatures of the first, second, and third zones can be controlled to be 550-629℃, and even more specifically, 553-626℃.

[0027] According to a specific embodiment of the present invention, the heating temperatures of the fourth, fifth, and sixth zones are generally controlled to be 595-657℃, for example, specific values ​​such as 595℃, 600℃, 610℃, 620℃, 630℃, 640℃, 650℃, 652℃, 655℃, and 657℃, as well as ranges with any two of the above specific values ​​as endpoints. Further, the heating temperatures of the fourth, fifth, and sixth zones can be controlled to be 597-655℃, and even more specifically, 600-652℃.

[0028] According to a specific embodiment of the present invention, the heating temperatures of the seventh, eighth, and ninth zones are generally controlled to be 628-674℃, for example, specific values ​​such as 628℃, 630℃, 633℃, 640℃, 650℃, 660℃, 669℃, 670℃, and 674℃, as well as ranges with any two of the above specific values ​​as endpoints. Further, the heating temperatures of the seventh, eighth, and ninth zones can be controlled to be 630-672℃, and even more specifically, 633-669℃.

[0029] In the above forming method, the top heating temperature of each heating section and heating zone is generally higher than the bottom heating temperature. In some specific embodiments, each heating section and heating zone in the heating furnace is equipped with heating devices at both the top and bottom, so the top and bottom heating temperatures of each heating section and heating zone can be controlled independently. In this invention, the distance between the heating device at the top of the same heating zone and the glass sheet is greater than the distance between the heating device at the bottom and the glass sheet. Correspondingly, the top heating temperature of the same heating zone is generally higher than the bottom heating temperature to ensure uniform heating of the upper and lower surfaces of the glass sheet.

[0030] Let the height of each heating zone be h. The glass sheet is located at the center line of the height direction of the heating zone. "Top" refers to the area above the glass sheet and whose vertical distance from the glass sheet is greater than 0 and less than or equal to 50%h. "Bottom" refers to the area below the glass sheet and whose vertical distance from the glass sheet is greater than 0 and less than or equal to 20%h.

[0031] According to a specific embodiment of the present invention, the top heating temperature of the first zone, the second zone, and the third zone can be controlled to be 560-631℃, for example, specific values ​​such as 560℃, 562℃, 565℃, 570℃, 580℃, 590℃, 600℃, 610℃, 620℃, 626℃, 629℃, 630℃, and 631℃, as well as a range with any two of the above specific values ​​as endpoints, further, it can be 562-629℃, and even further, it can be controlled to be 565-626℃.

[0032] According to a specific embodiment of the present invention, the bottom heating temperature of the first zone, the second zone, and the third zone can be controlled to be 548-617℃, for example, specific values ​​such as 548℃, 550℃, 553℃, 560℃, 570℃, 580℃, 590℃, 600℃, 610℃, 612℃, 615℃, and 617℃, as well as a range with any two of the above specific values ​​as endpoints, further, it can be 550-615℃, and even further, it can be 553-612℃.

[0033] According to a specific embodiment of the present invention, the top heating temperature of the fourth, fifth and sixth zones can be 606-657°C, for example, specific values ​​such as 606°C, 610°C, 620°C, 630°C, 640°C, 650°C, 657°C, etc., and a range with any two of the above specific values ​​as endpoints, further can be 608-655°C, and even further can be 611-652°C.

[0034] According to a specific embodiment of the present invention, the bottom heating temperature of the fourth, fifth and sixth zones can be controlled to be 595-650℃, for example, specific values ​​such as 595℃, 597℃, 600℃, 610℃, 620℃, 630℃, 640℃, 645℃, 648℃, 650℃, etc., and a range with any two of the above specific values ​​as endpoints, further, it can be 597-648℃, and even further, it can be 600-645℃.

[0035] According to a specific embodiment of the present invention, the top heating temperature of the seventh, eighth and ninth zones can be controlled to be 633-674°C, for example, specific values ​​such as 633°C, 640°C, 650°C, 660°C, 670°C, 674°C, etc., and a range with any two of the above specific values ​​as endpoints, further, it can be 635-672°C, and even further, it can be 638-669°C.

[0036] According to a specific embodiment of the present invention, the bottom heating temperature of the seventh, eighth and ninth zones can be controlled to 628-670°C, for example, to specific values ​​such as 628°C, 630°C, 640°C, 650°C, 660°C, 670°C, etc., and to a range with any two of the above specific values ​​as endpoints, further to 630-668°C, and even further to 633-665°C.

[0037] In the above forming method, heating devices are respectively installed on the top and bottom left, middle, and right sides of each heating zone. Each heating zone then has separate heating temperatures for the top left, top middle, top right, bottom left, bottom middle, and bottom right positions, and these temperatures can be controlled individually. Here, the length of a heating zone is denoted as d. "Middle" refers to the position located at the centerline of each heating zone (the centerline perpendicular to the glass sheet transport direction, i.e., the centerline along the length of the heating zone); "left" refers to the area located to the left of the centerline of the heating zone, with a horizontal distance greater than 0 and less than or equal to 30%d from the centerline; and "right" refers to the area located to the right of the centerline of the heating zone, with a horizontal distance greater than 0 and less than or equal to 30%d from the centerline.

[0038] In some specific embodiments, the heating device may be a heating element. Specifically, each heating zone has at least one heating element at its top and bottom; furthermore, each heating zone has heating elements located at its top left, top middle, top right, bottom left, bottom middle, and bottom right. The heating temperature at each location in each heating zone may be the temperature of the heating element.

[0039] The heating furnace of this invention heats the glass sheet simultaneously from the top, bottom, left, middle, and right sides of the same heating zone, ensuring uniform heating at all locations on the glass sheet (including between the upper and lower surfaces, and between the larger, middle, and smaller ends). This results in better microscopic optical properties, which can be assessed using a refractometer, a Mohr's scanner, etc., to meet the optical requirements of automotive windshields. By employing the above heating method and controlling the molding temperature within an appropriate range, the glass can achieve a suitable viscosity, allowing it to flow and be molded without causing shape instability due to excessive flow. This facilitates a tight fit between the glass sheet and the die / cone during subsequent pressing and molding stages, resulting in better processing outcomes.

[0040] In the forming method provided by this invention, the heating temperatures of the first three zones, the middle three zones, and the last three zones are lower than those of the first three zones, the middle three zones, and the last three zones in existing forming methods. By reducing the heating temperature, the optical properties of the formed glass can be significantly improved, especially its microscopic optical properties; for example, optical distortion can be significantly reduced (by 5-10 mdpt). Furthermore, by controlling the average heating temperature of each of the first three zones, the middle three zones, and the last three zones within a certain range, this invention ensures that the curvature of the glass precisely meets the requirements. In some specific embodiments, for the glass sheet used for side windows, the curvature range of the glass sheet after heat treatment can meet the following requirements: radius of curvature ≥ 1000 mm; for the glass sheet used for windshields, the curvature range of the glass after heat treatment can meet the following requirements: radius of curvature 200-3000 mm.

[0041] According to a specific embodiment of the present invention, the average heating temperature of the first three zones in the forming method of the present invention is more than 14°C lower than the average heating temperature of the first three zones in the existing automotive glass sheet forming method. The glass sheet used in the present invention has a low softening point, and the corresponding forming temperature is also low. By controlling the average heating temperature of the first three zones in the forming method within a certain range, the curvature of the glass can be made to meet the requirements. For example, the average heating temperature of the top middle of the first three zones in the existing forming method for green glass sheets is 607°C, while the average heating temperature of the top middle of the first three zones in the forming method of the present invention is 593°C, which is 14°C lower than the average heating temperature of the same position in the existing forming method.

[0042] Furthermore, in the molding method of the present invention, the top heating temperature of the first three zones is 4°C higher than the bottom heating temperature.

[0043] In the above molding method, the top heating temperature of the first region is 560-596°C, further can be 557-599°C, and even further can be 565-591°C.

[0044] In the above molding method, the bottom heating temperature of the first region is 548-592℃, which can be further 550-590℃, and even further 553-587℃.

[0045] In the above molding method, the top heating temperature of the second zone is 569-615°C, further can be 571-613°C, and even further can be 574-610°C.

[0046] In the above molding method, the bottom heating temperature of the second zone is 561-602℃, further can be 563-600℃, and even further can be 566-597℃.

[0047] In the above molding method, the top heating temperature of the third zone is 592-631°C, which can be further 594-629°C, and even further 597-626°C.

[0048] In the above molding method, the bottom heating temperature of the third zone is 571-617℃, further can be 573-615℃, and even further can be 576-612℃.

[0049] According to a specific embodiment of the present invention, the average heating temperature of the three intermediate zones in the inventive molding method is more than 18°C ​​lower than the average heating temperature of the three intermediate zones in the existing automotive glass sheet molding method.

[0050] Furthermore, in the molding method of the invention, the top heating temperature of the three middle zones is more than 7°C higher than the bottom heating temperature.

[0051] In the above molding method, the top heating temperature of the fourth zone is 606-646℃, further can be 608-644℃, and even further can be 611-641℃.

[0052] In the above molding method, the top heating temperature of the fourth zone is 595-638℃, further can be 597-636℃, and even further can be 600-633℃.

[0053] In the above molding method, the top heating temperature of the fifth zone is 616-656℃, which can be further 618-654℃, and even further 621-651℃.

[0054] In the above molding method, the bottom heating temperature of the fifth zone is 602-646℃, further can be 604-644℃, and even further can be 607-641℃.

[0055] In the above molding method, the top heating temperature of the sixth zone is 618-657℃, further can be 620-655℃, and even further can be 623-652℃.

[0056] In the above molding method, the bottom heating temperature of the sixth zone is 608-650℃, further can be 610-648℃, and even further can be 613-645℃.

[0057] According to a specific embodiment of the present invention, the average heating temperature of the last three zones of the inventive molding method is more than 4°C lower than the average heating temperature of the last three zones of the existing automotive glass sheet molding method.

[0058] Furthermore, in the molding method of the invention, the top heating temperature of the last three zones is more than 10°C higher than the bottom heating temperature.

[0059] In the above molding method, the top heating temperature of the seventh zone is 633-673℃, further can be 635-671℃, and even further can be 638-668℃.

[0060] In the above molding method, the bottom heating temperature of the seventh zone is 628-666℃, further can be 630-664℃, and even further can be 633-661℃.

[0061] In the above molding method, the top heating temperature of the eighth zone is 634-674℃, further can be 636-672℃, and even further can be 639-669℃.

[0062] In the above molding method, the bottom heating temperature of the eighth zone is 630-670℃, further can be 632-668℃, and even further can be 635-665℃.

[0063] In the above molding method, the top heating temperature of the ninth zone is 633-674℃, further can be 635-672℃, and even further can be 638-669℃.

[0064] In the above molding method, the bottom heating temperature of the ninth zone is 628-669℃, further can be 630-667℃, and even further can be 633-664℃.

[0065] Furthermore, in the forming method of the present invention, the heating temperature at the same height in each heating zone can be symmetrically distributed along the centerline so that the surface of the glass sheet is heated uniformly.

[0066] According to a specific embodiment of the present invention, the heating furnace may include at least one of a single-piece pressing forming furnace, a self-weight bending forming furnace, and a double-piece pressing forming furnace.

[0067] According to a specific embodiment of the present invention, the glass sheet after being processed in the heating furnace is generally sent from the sheet exit end (ninth zone) of the heating furnace to the forming section outside the furnace for pressing and forming to form the low-absorption, high-transmittance glass.

[0068] According to a specific embodiment of the present invention, the length of each heating zone in zones one through nine is generally 1500-4000 mm. Zones one through eight are typically used as heating zones, whose main functions are to heat the glass sheet (zones one through seven) and to maintain its temperature (zone eight). Zone nine serves as a heating transfer zone, which, in addition to maintaining the heating temperature of the glass sheet (similar to or basically the same as the heating temperature of zone eight), is also used to transport the glass sheet to the forming section. Accordingly, the transmission speed of the glass sheet in the first to eighth zones can be 50-300 mm / s, for example, specific values ​​such as 50 mm / s, 100 mm / s, 150 mm / s, 200 mm / s, 250 mm / s, 300 mm / s, etc., and a range with any two of the above specific values ​​as endpoints; the glass sheet is transmitted at a uniform speed in the ninth zone, and the transmission speed in the ninth zone is faster than that in the first eight zones. Specifically, the transmission speed of the glass sheet in the ninth zone can be 800-1500 mm / s, for example, specific values ​​such as 800 mm / s, 900 mm / s, 1000 mm / s, 1100 mm / s, 1200 mm / s, 1300 mm / s, 1400 mm / s, 1500 mm / s, etc., and a range with any two of the above specific values ​​as endpoints. In a specific implementation plan, the transmission speed of the glass sheet in each heating zone can be adjusted according to the actual thickness of the glass sheet. For example, for a thicker glass sheet, a lower transmission speed can be used and the heating temperature can be increased to ensure that the glass sheet is fully heated.

[0069] According to a specific embodiment of the present invention, the pressing process may include: sending a heat-treated glass sheet to a forming section having a concave mold and a convex mold; using the concave mold to lift the glass sheet until the upper surface of the glass sheet contacts the convex mold; the glass sheet contacts the concave mold and the convex mold simultaneously and is pressed; after pressing, the convex mold holds the glass sheet and rises; then the transfer shuttle of the forming section extends to below the convex mold and the glass sheet; after the transfer shuttle reaches its stroke position, the convex mold and the glass sheet separate; the glass sheet falls onto the transfer shuttle and is conveyed by the transfer shuttle to the annealing zone for annealing, thus completing the pressing process.

[0070] In the above-mentioned pressing and molding process, the concave mold in the molding section is located below the glass sheet, and the concave surface is a quadrilateral mold frame structure. The concave mold is in contact with the periphery of the glass sheet.

[0071] In the above forming process, the punch in the forming section is located above the glass sheet and has an arc-shaped surface that can contact the entire upper surface of the glass sheet. Furthermore, the surface of the punch may have several (two or more) small holes regularly distributed on it, the diameter of which is generally less than 5 mm. These small holes allow the punch to vacuum-adsorb and move the glass sheet.

[0072] In the above-mentioned pressing process, the pressing time is the time during which the glass sheet contacts the concave mold and the convex mold simultaneously (i.e., the mold closes). The pressing time is generally less than 2 seconds.

[0073] The present invention also provides a low-absorption, high-transmittance (SuperClear, abbreviated as SC) glass, which is obtained by the above-described forming method.

[0074] In some specific embodiments, the optical distortion of the low-absorption, high-transmittance glass and / or the laminated glass made of the low-absorption, high-transmittance glass is ≤150 mdpt; the tensile stress of the low-absorption, high-transmittance glass and / or the laminated glass made of the low-absorption, high-transmittance glass is <12 MPa; and the edge compressive stress of the low-absorption, high-transmittance glass and / or the laminated glass made of the low-absorption, high-transmittance glass is >12 MPa. The laminated glass may comprise two layers of the aforementioned low-absorption, high-transmittance glass, with a PVB (polyvinyl butyral) or similar adhesive layer sandwiched between the two glass plates.

[0075] In some specific implementations, the refractive index, fit, and other parameters of the laminated glass made of the low-absorption, high-transparency glass meet the requirements of GB9656-2003 "Automotive Safety Glass".

[0076] In some specific embodiments, the glass substrate has a transmittance of 90% or more, and further, 91% or more, for light with a wavelength of 800-1600 nm. The low-absorption, high-transmittance glass manufactured from the glass substrate using the molding method of this invention also maintains the above-mentioned transmittance. The low-absorption, high-transmittance glass can achieve a transmittance of 90% or more, and further, 91% or more, for light with a wavelength of 800-1600 nm, and even further, 91.2% or more.

[0077] In some specific embodiments, the light absorption coefficient of the glass substrate for light with wavelengths of 800-1600 nm is 0.04-0.2 cm⁻¹. -1 Furthermore, it can reach 0.04-0.1cm. -1The low-absorption, high-transmittance glass manufactured using the molding method of this invention also maintains its low-absorption performance. This low-absorption, high-transmittance glass has a light absorption coefficient of 0.04-0.2 cm⁻¹ for light with wavelengths of 800-1600 nm. -1 Furthermore, it can reach 0.04-0.1cm. -1 .

[0078] This invention also provides a vehicle window glass made of the aforementioned low-absorption, high-transmittance glass. In some specific embodiments, the vehicle window glass can be a windshield, rear windshield, side window, sunroof, corner window, etc. The low-absorption, high-transmittance glass provided by this invention has high optical transmittance in the near-infrared band, which can meet the light transmittance requirements of optical sensors such as LiDAR and infrared cameras, and thus can be used to manufacture functionally integrated vehicle window glass, such as a functionally integrated windshield.

[0079] The beneficial effects of this invention include:

[0080] The low-absorption, high-transmittance glass provided by this invention has a low molding temperature, low absorption, and high light transmittance, especially in the 800-1600nm light band. This low-absorption, high-transmittance glass can meet the light transmittance requirements of optical sensors and can be used in functionally integrated glass applications, such as windshields for LiDAR-embedded products. Detailed Implementation

[0081] In order to provide a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention will now be described in detail below, but it should not be construed as limiting the scope of implementation of the present invention.

[0082] The glass sheets used in the following experiments were sourced from the ultra-clear glass series of Shandong Jinjing Technology Co., Ltd.

[0083] Example 1

[0084] This embodiment provides a method for forming low-absorption, high-transmittance glass, the method comprising:

[0085] S1. The glass sheet is sent into a heating furnace for heating treatment;

[0086] S2. The glass sheet that has undergone heat treatment is transferred from the heating furnace to the forming section for pressing and forming to obtain low-absorption, high-transmittance glass, denoted as SC glass.

[0087] The glass substrate used in this embodiment is a low-absorption, high-transmittance glass substrate with an iron content of less than 150 ppm (more specifically, less than 130 ppm, or less than 110 ppm, or less than 90 ppm); the softening point of the glass substrate is 710±3℃, and the annealing point is 545±5℃. The thickness of the glass substrate is 2.1 mm.

[0088] The heating furnace used in this embodiment is a single-piece pressing and molding furnace.

[0089] The heating furnace is equipped with a preheating section, a heating section, and a constant-temperature gradual change section. Specifically, the heating furnace has a total of 9 heating zones. Taking the glass sheet conveying direction as left to right, the heating zones are, from left to right, zone 1, zone 2, zone 3, zone 4, zone 5, zone 6, zone 7, zone 8, and zone 9. The heating temperature gradually increases from zone 1 to zone 9. Zones 1 to 3 constitute the preheating section, zones 4 to 7 constitute the heating section, and zones 8 and 9 constitute the constant-temperature gradual change section.

[0090] Each heating zone is equipped with heating wires at the top and bottom as heating devices; the heating temperature at the top of the same heating zone is higher than the heating temperature at the bottom.

[0091] Heating wires are installed on the left, middle, and right sides at the same height. That is, each heating zone has heating wires on the top left, top middle, top right, bottom left, bottom middle, and bottom right sides respectively. The temperature of each heating wire is independently controlled, and the heating wires in each heating zone can heat the glass sheet simultaneously. At the same height in the same heating zone, the heating temperature gradually increases from left to right.

[0092] Here, the height of each heating zone is denoted as h, and the glass sheet is located on the center line of the height direction of the heating zone. "Top" refers to the area above the glass sheet and whose vertical distance from the glass sheet is greater than 0 and less than or equal to 50%h; "Bottom" refers to the area below the glass sheet and whose vertical distance from the glass sheet is greater than 0 and less than or equal to 20%h.

[0093] Let the length of each heating zone be d. The corresponding areas at the same height, namely the middle, left, and right, are as follows: "Middle" refers to the area located at the center line of the length direction of the heating zone; "Left" refers to the area located to the left of the center line of the length direction and whose horizontal distance from the center line is greater than 0 and less than or equal to 30%d; "Right" refers to the area located to the right of the center line of the length direction and whose horizontal distance from the center line is greater than 0 and less than or equal to 30%d.

[0094] The heating temperatures at each location in each heating zone of S1 are shown in Table 1.

[0095] The forming section in S2 that performs pressing includes a punch, a die, and a transfer shuttle.

[0096] The punch is located above the glass sheet and has an arc-shaped surface that can contact the entire upper surface of the glass sheet. The surface of the punch may have several (two or more) small holes regularly distributed on it, with the diameter of the holes generally less than 5 mm. Through these holes, the punch can vacuum-adhere the glass sheet, causing it to move.

[0097] The concave mold is located below the glass sheet, and its concave surface is a quadrilateral mold frame structure. The concave mold is in contact with the periphery of the glass sheet.

[0098] The pressing process of S2 specifically includes: using a concave mold to lift the glass sheet until the upper surface of the glass sheet contacts the convex mold; the glass sheet contacts the concave mold and the convex mold simultaneously (i.e., mold closing) and is pressed; the pressing temperature is controlled to be lower than the heating temperature of the fourth to ninth zones in the heating furnace; the pressing time is controlled to be less than 2 seconds; after pressing, the convex mold holds the glass sheet and rises, and then the transfer shuttle extends to the bottom of the convex mold and the glass sheet; after the transfer shuttle reaches its stroke, the convex mold and the glass sheet separate; the glass sheet falls onto the transfer shuttle and is transferred by the transfer shuttle to the annealing zone for annealing (annealing temperature is 500-600℃, annealing time is 10-30min), thus completing the pressing process.

[0099] Comparative Example 1

[0100] This comparative example provides a method for forming a green glass sheet. The method includes feeding the green glass sheet into a heating furnace for heating treatment, and then sending it out of the heating furnace to a forming section for pressing and forming to obtain green glass, denoted as G glass.

[0101] The glass sheet used in this comparative example is a green glass sheet with an iron content of 800ppm-900ppm; its softening point is 725-730℃, and its annealing point is 560-620℃. The thickness of the glass sheet is 2.1mm.

[0102] The heating furnace used in this comparative example is the same as that in Example 1, and the distribution of each heating zone and the distribution of the heating wires are also the same as in Example 1.

[0103] The heating temperatures at each location in each heating zone are shown in Table 1 (unit: °C). "Top Left" represents the heating temperature at the top left side, "Top Center" represents the heating temperature at the top center, "Top Right" represents the heating temperature at the top right side, "Bottom Left" represents the heating temperature at the bottom left side, "Bottom Center" represents the heating temperature at the bottom center, and "Bottom Right" represents the heating temperature at the bottom right side. The temperatures in Table 1 are thermocouple temperature readings.

[0104] Table 1

[0105]

[0106] As shown in Table 1, the molding temperature of existing green glass substrate molding methods is 576-658℃, while the molding temperature of the molding method of this invention for low-absorption, high-transmittance glass substrates is 553-643℃. The molding method provided by this invention has a lower temperature.

[0107] Example 2

[0108] This embodiment provides a method for forming low-absorption, high-transmittance glass, the method comprising:

[0109] S1. The glass sheet is sent into a heating furnace for heating treatment;

[0110] S2. The glass sheet that has undergone heat treatment is transferred from the heating furnace to the forming section for pressing and forming to obtain low-absorption, high-transmittance glass, denoted as SC glass.

[0111] The glass substrate used in this embodiment is a low-absorption, high-transmittance glass substrate with an iron content of less than 150 ppm (more specifically, less than 130 ppm, or less than 110 ppm, or less than 90 ppm); the softening point of the glass substrate is 710±3℃, and the annealing point is 545±5℃. The thickness of the glass substrate is 6 mm.

[0112] The molding method in this embodiment is similar to that in Embodiment 1, except that the heating temperature in S1 is different. The heating temperatures at each location in each heating zone in this embodiment are shown in Table 2 (SC sample).

[0113] Comparative Example 2

[0114] This comparative example provides a method for forming a green glass sheet. The method includes feeding the green glass sheet into a heating furnace for heating treatment, and then sending it out of the heating furnace to a forming section for pressing and forming to obtain green glass, denoted as G glass.

[0115] The glass sheet used in this comparative example is a green glass sheet with an iron content of 800ppm-900ppm; its softening point is 725-730℃, and its annealing point is 560-620℃. The thickness of the glass sheet is 6mm.

[0116] The heating furnace used in this comparative example is the same as that in Example 2, and the distribution of each heating zone and the distribution of the heating wires are also the same as in Example 2.

[0117] The heating temperatures at each location in each heating zone are shown in Table 2 (Sample G). The units for the values ​​in Table 2 are °C. The temperatures in Table 2 are thermocouple readings.

[0118] Table 2

[0119]

[0120]

[0121] As shown in Table 2, when the thickness of the glass sheet is adjusted to 6mm, the forming temperature of existing green glass sheet forming methods is 596-678℃, while the forming temperature of the forming method of the present invention for low-absorption, high-transmittance glass sheet is 578-669℃. Comparatively, the forming method provided by the present invention has a lower heating temperature.

[0122] Test Example 1

[0123] The optical transmittance in the near-infrared band (800-1600 nm) of SC glass obtained according to the molding methods of Examples 1 and 2, and G glass obtained according to the molding methods of Comparative Examples 1 and 2, was tested according to standard GB / T5137.2-2020, "Test Methods for Automotive Safety Glass, Part 2: Optical Performance Tests". The laser wavelength used for the light absorption coefficient was 800-1600 nm, and the formula for calculating the light absorption coefficient is as follows:

[0124]

[0125] K is the light absorption coefficient of the glass substrate, l is the thickness of the glass substrate in the stacking direction; n is the refractive index of the glass substrate for a specific wavelength of laser light, and T is the transmittance of the glass substrate for a specific wavelength of laser light.

[0126] The low-absorption, high-transmittance glass substrate used in the molding method of Example 1 has an iron content of 99 ppm, a softening point of 710°C, an annealing point of 545°C, and a light absorption coefficient of 0.09 cm⁻¹. -1 .

[0127] The green glass substrate used in the molding method of Comparative Example 1 had an iron content of 805 ppm, a softening point of 728℃, an annealing point of 592℃, and a light absorption coefficient of 3.76 cm⁻¹. -1 .

[0128] The transmittance of the 2.1 mm SC glass manufactured in Example 1 was measured to be 91.2% (≥91%) in the 800-1600 nm range; the transmittance of the 2.1 mm green glass manufactured in Comparative Example 1 was 61.23% in the 800-1600 nm range.

[0129] The transmittance of the 6mm SC glass manufactured in Example 2 was measured to be 90.6% in the 800-1600nm range; the transmittance of the 6mm green glass manufactured in Comparative Example 2 was 48% in the 800-1600nm range.

[0130] In addition, the laminated glass made from the SC glass of Examples 1 and 2 was tested for optical distortion, tensile stress, edge compressive stress, refractive index, and fit. The laminated glass consists of two SC glass panes and a 0.76 mm thick PVB adhesive layer located between the two glass panes.

[0131] The laminated glass made from the low-absorption, high-transmittance glass of Example 1 was found to have the following properties: optical distortion of 129 mdpt; tensile stress of 10.5 MPa and edge compressive stress of 13.1 MPa; the laminated glass made from the low-absorption, high-transmittance glass of Example 2 had an optical distortion of 148 mdpt; tensile stress of 11.2 MPa and edge compressive stress of 15.3 MPa.

[0132] The laminated glass made from SC glass in Examples 1 and 2 meets the requirements of GB9656-2003 "Automotive Safety Glass" in terms of refractive index and fit.

[0133] As can be seen from the above results, the transmittance of existing glass in the near-infrared band is low, which makes it difficult to meet the requirements of optical sensor components for the optical performance of glass. However, the low-absorption high-transmittance glass produced by the above-mentioned molding method provided by the present invention can achieve an optical transmittance of more than 91% in the near-infrared band, which can meet the requirements of LiDAR and other sensors for optical transmittance and can be used to prepare functional integrated windshields and other automotive window glass.

Claims

1. A method for forming a low-absorption, high-transmittance glass, the method comprising: The glass sheet is placed in a heating furnace for heating treatment, and then pressed into shape to obtain the low-absorption, high-transmittance glass. The heating furnace includes a preheating section, a heating section, and a constant temperature gradual change section connected in sequence. The inlet temperature of the preheating section is 548-596℃, and the outlet temperature of the preheating section is 571-631℃. The outlet temperature of the preheating section is higher than the inlet temperature. The inlet temperature of the heating section is 595-646℃, and the outlet temperature of the heating section is 628-673℃. The outlet temperature of the heating section is higher than the inlet temperature. The temperature of the constant temperature gradual change section is 628-674℃; The inlet temperature of the heating section is greater than or equal to the outlet temperature of the preheating section, and the difference between the inlet temperature of the constant temperature gradual change section and the outlet temperature of the heating section is ≥-3℃.

2. The molding method according to claim 1, wherein, The heating rate of the preheating section is 0.07-5.4℃ / s; The heating rate of the heating section is 0.01-4.0℃ / s.

3. The molding method according to claim 1 or 2, wherein, The heating furnace has nine heating zones, which are numbered from zone 1 to zone 9 from the inlet to the outlet. Zones 1 to 3 are preheating zones, zones 4 to 7 are heating zones, and zones 8 to 9 are constant temperature gradual change zones. From zone one to zone nine, the heating temperature gradually increases; each heating zone heats the glass sheet simultaneously from both above and below. The heating temperatures for Zone 1, Zone 2, and Zone 3 are 548-631℃, for Zone 4, Zone 5, and Zone 6 are 595-657℃, and for Zone 7, Zone 8, and Zone 9 are 628-674℃.

4. The molding method according to claim 3, wherein, The top heating temperature in the same heating zone is higher than the bottom heating temperature. The top heating temperatures of the first, second, and third zones are 560-631℃, and the bottom heating temperatures of the first, second, and third zones are 548-617℃, respectively. The top heating temperatures of the fourth, fifth, and sixth zones are 606-657℃, and the bottom heating temperatures of the fourth, fifth, and sixth zones are 595-650℃, respectively. The top heating temperatures of zones 7, 8, and 9 are 633-674℃, and the bottom heating temperatures of zones 7, 8, and 9 are 628-670℃, respectively.

5. The molding method according to claim 3, wherein, The top heating temperature of the first zone is 560-596℃, and the bottom heating temperature of the first zone is 548-592℃.

6. The molding method according to claim 3, wherein, The top heating temperature of the second zone is 569-615℃, and the bottom heating temperature of the second zone is 561-602℃.

7. The molding method according to claim 3, wherein, The top heating temperature of the third zone is 592-631℃, and the bottom heating temperature of the third zone is 571-617℃.

8. The molding method according to claim 3, wherein, The top heating temperature of the fourth zone is 606-646℃, and the bottom heating temperature of the fourth zone is 595-638℃.

9. The molding method according to claim 3, wherein, The top heating temperature of the fifth zone is 616-656℃, and the bottom heating temperature of the fifth zone is 602-646℃.

10. The molding method according to claim 3, wherein, The top heating temperature of the sixth zone is 618-657℃, and the bottom heating temperature of the sixth zone is 608-650℃.

11. The molding method according to claim 3, wherein, The top heating temperature of the seventh zone is 633-673℃, and the bottom heating temperature of the seventh zone is 628-666℃.

12. The molding method according to claim 3, wherein, The top heating temperature of the eighth zone is 634-674℃, and the bottom heating temperature of the eighth zone is 630-670℃.

13. The molding method according to claim 3, wherein, The top heating temperature of the ninth zone is 633-674℃, and the bottom heating temperature of the ninth zone is 628-669℃.

14. The molding method according to claim 3, wherein, The length of each heating zone in zones one through nine is 1500-4000 mm; The glass sheet is transported at a uniform speed from the first zone to the eighth zone, with a transport speed of 50-300 mm / s. The glass sheet is transported at a constant speed in the ninth zone, with a transport speed of 800-1500 mm / s.

15. The molding method according to claim 1, wherein, The thickness of the glass sheet is 1.6-6mm; And / or, the iron content of the glass substrate is ≤150ppm; And / or, the light absorption coefficient of the glass substrate for light with wavelengths of 800-1600 nm is 0.04-0.2 cm⁻¹. -1 .

16. The molding method according to claim 1, wherein, The softening point of the glass sheet is 707-713℃, and the annealing point is 540-550℃.

17. A low-absorption, high-transmittance glass, which is formed by the forming method according to any one of claims 1-16.

18. The low-absorption, high-transmittance glass according to claim 17, wherein, The optical distortion of the low-absorption, high-transmittance glass is ≤150 mdpt; the tensile stress of the low-absorption, high-transmittance glass is <12 MPa; and the edge compressive stress of the low-absorption, high-transmittance glass is >12 MPa.

19. The low-absorption, high-transmittance glass according to claim 17, wherein, The low-absorption, high-transmittance glass has a transmittance of over 90% for light with wavelengths of 800-1600nm.

20. A vehicle window glass made of the low-absorption, high-transmittance glass according to any one of claims 17-19.

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