Low-absorption high-transmittance glass, forming method thereof and vehicle window glass

Abstract

The invention provides low-absorption high-transmittance glass, a forming method thereof and vehicle window glass. The forming method comprises the following steps: placing a glass sheet in a heating furnace for heating treatment, and then pressing and forming; the heating furnace comprises a preheating section, a heating section and a constant-temperature transition section which are sequentially connected; the inlet temperature of the preheating section is 548-596 DEG C, the outlet temperature of the preheating section is 571-631 DEG C, and the outlet temperature of the preheating section is higher than the inlet temperature; the inlet temperature of the heating section is 595-646 DEG C, the outlet temperature is 628-673 DEG C, and the outlet temperature of the heating section is higher than the inlet temperature; the temperature of the constant-temperature transition section is 628-674 DEG C; the difference value between the inlet temperature of the constant-temperature transition section and the outlet temperature of the heating section is larger than or equal to-3 DEG C. The low-absorption high-transmittance glass can meet the requirement of an optical sensor for optical transmittance and can be used for manufacturing functional integration glass.

Description

Technical Field

[0001] The invention relates to the technical field of automobile glass manufacturing, and in particular to a low-absorption and high-transmittance glass and a molding method thereof and a vehicle window glass. Background Art

[0002] The raw materials used for automobile glass, especially the front windshield, are generally automobile-grade raw materials produced by float glass process. Automobile-grade raw materials include: ordinary white glass (Clear, referred to as C), green glass (Green, referred to as G), heat-absorbing green glass (SolarGreen, referred to as SG) and super heat-absorbing green glass (SolarDark, referred to as SD).

[0003] At present, the bump area of ​​automotive glass, especially the front windshield, integrates more and more optical sensor elements, such as LiDAR, infrared cameras, etc. These optical sensors have higher and higher requirements for the front windshield, requiring the maximum optical transmittance in the corresponding near-infrared band, such as 800-1600nm. The existing automotive glass raw sheets cannot meet the above requirements, and glass raw sheets with low absorption and high transmittance in the corresponding band are needed. The above-mentioned glass raw sheets with low absorption and high transmittance optical properties in the corresponding band have different molding parameters from the existing automotive glass raw sheets, and it is necessary to provide a molding method for this type of glass raw sheets. Summary of the invention

[0004] In order to solve the above problems, the purpose of the present invention is to provide a low-absorption and high-transmittance glass and a molding method thereof and a vehicle window glass. The low-absorption and high-transmittance glass has a low molding temperature, low absorption and high light transmittance, can meet the requirements of optical sensors for optical transmittance, and can be used for the manufacture of functional integrated glass.

[0005] In order to achieve the above object, the present invention provides a method for forming low-absorption and high-transmittance glass, the forming method comprising:

[0006] The glass raw sheet is placed in a heating furnace for heating treatment, and then pressed into shape to obtain the low-absorption and high-transmittance glass, wherein the heating furnace comprises 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°C, the outlet temperature of the preheating section is 571-631°C, and the outlet temperature of the preheating section is higher than the inlet temperature of the preheating section; the inlet temperature of the heating section is 595-646°C, the outlet temperature of the heating section is 628-673°C, and the outlet temperature of the heating section is higher than the inlet temperature of the heating section; the temperature of the constant temperature gradient section is 628-674°C; 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°C (i.e., the inlet temperature of the constant temperature gradient section minus the outlet temperature of the heating section is ≥-3°C).

[0007] In the above-mentioned forming method, the preheating section is used to heat the glass sheet in the first stage, the heating section is used to heat the glass sheet in the second stage, and the constant temperature gradient section is used to keep the glass sheet warm and transfer it to the subsequent process. The preheating section and the heating section can be roughly divided according to the softening temperature of the glass sheet. The heating temperature of the glass sheet in the preheating section is generally lower than the softening temperature of the glass sheet, and the heating temperature of the glass sheet in the heating section is generally higher than the softening temperature of the glass sheet. Therefore, the glass sheet begins to soften after entering the heating section. It can be understood that in actual production, the heating temperature of the heating furnace is generally not equal to the heating temperature of the glass. Therefore, the heating temperature of each section of the heating furnace can be adjusted accordingly based on the softening temperature range of the glass, as long as the heating degree is reached so that 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 the present invention, the softening temperature of the glass sheet refers to the temperature at which the glass begins to deform or soften under the action of its own weight. For example, the softening temperature of the low-absorption and high-transmittance glass sheet such as the ultra-white glass sheet is about 606°C. The softening temperature of glass is generally 100-120°C 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 by the Littleten glass fiber vertical extension method, and the process is as follows: the heating suspension density is 2.5g / cm 3 When the glass fiber is about 0.55-0.75mm in diameter and 229mm in length, the temperature when it is stretched at a speed of 1mm / min is the softening point.

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

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

[0011] In some specific embodiments, the heating rate of the preheating section may be greater than or equal to the heating rate of the heating section. The temperature change range in the constant temperature gradient section is small and the heating rate is very small, and the heating rate of the constant temperature gradient section is generally smaller than the heating rates of the preheating section and the heating section.

[0012] In the above-mentioned forming method, the heating method in each section (preheating section, heating section, constant temperature gradient section) can be common heating methods such as uniform heating, variable heating, and step heating. The present invention has no special limitation on the heating method.

[0013] The present invention divides the heating furnace into three main heating treatment sections according to function: a preheating section, a heating section, and a constant temperature gradient 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). The present invention has no special restriction on the number of further divisions of the preheating section, the heating section, and the constant temperature gradient 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 is further described below by taking a heating furnace having 9 heating zones as an example:

[0015] In the above-mentioned forming method, the heating furnace can specifically have 9 heating zones. From the sheet inlet end to the sheet outlet end of the heating furnace, the heating zones are successively the first zone to the ninth zone, the first zone to the third zone are the preheating section, the fourth zone to the seventh zone are the heating section, and the eighth zone to the ninth zone are the constant temperature gradient section; from the first zone to the ninth zone, the heating temperature gradually increases (the overall trend is an upward trend, and the situation where the temperatures of adjacent heating zones are similar is not excluded, for example, the temperatures of the seventh zone, the eighth zone, and the ninth zone can be close); each heating zone heats the glass sheet from the top and the bottom of the glass sheet at the same time; wherein, the heating temperatures of the first zone, the second zone, and the third zone are 548-631°C, respectively, the heating temperatures of the fourth zone, the fifth zone, and the sixth zone are 595-657°C, respectively, and the heating temperatures of the seventh zone, the eighth zone, and the ninth zone are 628-674°C, respectively.

[0016] According to a specific embodiment of the present invention, the glass sheet applicable to the above-mentioned molding method provided by the present invention is a low-absorption, high-transmittance glass sheet. The iron content of ordinary glass sheets is high (for example, the iron content of ordinary white glass is 700-900ppm, the iron content of ordinary green glass is 5000ppm, and the iron content of absorbed green glass is about 7000ppm). The iron content of the glass sheet applicable to the present invention is lower, generally below 150ppm, further below 130ppm or below 110ppm, and further below 90ppm. The iron content is the weight content of iron oxide. The lower the iron content of the glass sheet, the lower the absorption.

[0017] In addition, the softening point temperature of ordinary glass sheets is relatively high, about 725-730°C, while the softening point temperature of the glass sheets applicable to the present invention is relatively low, about 707-713°C; the annealing point of the glass sheets applicable to the present invention is generally 540-550°C, that is, the softening point temperature is about 28-32% (such as 30%) higher than the annealing point temperature. The softening point temperature of the glass sheets applicable to the present invention is proportional to the annealing point temperature, and the higher the softening point temperature, the higher the corresponding annealing point temperature. In the above-mentioned molding method of the present invention, the heating temperature of the first zone can be higher than the annealing point temperature of the glass sheets.

[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 glass sheet with a thickness of 2.1mm (2.1C glass sheet, specifically ultra-white glass), used for the manufacture of front windshields; or a glass sheet with a thickness of less than 6mm, used for the manufacture of corner window glasses.

[0019] In the above forming method, the light absorption coefficient of the glass sheet to light with a wavelength of 800-1600nm can be 0.04-0.2cm -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 The light absorption coefficient can be 0.04-0.1 cm -1 .

[0020] In the present invention, the light absorption coefficient refers to the negative value of the natural logarithm of the internal transmittance of natural light passing through the glass sheet per centimeter. When the incident light is incident vertically on the glass sheet, the light intensity is attenuated due to the absorption of the glass sheet. The light absorption coefficient value can be calculated by measuring the natural light transmittance of the glass sheet. Specifically, the following formula can be used for calculation:

[0021]

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

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

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

[0025] In the above-mentioned forming method, along the sheet inlet end to the sheet outlet end of the heating furnace (that is, along the transmission direction of the original glass sheet from entering the furnace to exiting the furnace), the heating zones in the heating furnace are the first zone, the second zone, the third zone, the fourth zone, the fifth zone, the sixth zone, the seventh zone, the eighth zone, and the ninth zone, which are connected in sequence. From the first zone to the ninth zone, the heating temperature gradually increases. Among them, the first zone, the second zone, and the third zone can be called the first three zones, the fourth zone, the fifth zone, and the sixth zone can be called the middle three zones, and the seventh zone, the eighth zone, and the ninth zone can be called the last three zones. From the first zone to the ninth zone, the heating temperature gradually increases (the overall trend is an upward trend, and the situation where the temperatures of adjacent heating zones are similar is not excluded). Specifically, from the first zone to the seventh zone, the heating temperature gradually increases, the heating temperature of the eighth zone is similar to that of the seventh zone, and the temperature of the ninth zone is the same as or similar to the heating temperature of the eighth zone.

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

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

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

[0029] In the above-mentioned forming method, the top heating temperature of each heating section and each heating zone is generally higher than the bottom heating temperature. In some specific embodiments, each heating section and each heating zone in the heating furnace is provided with heating devices at the top and bottom, and the top heating temperature and the bottom heating temperature of each heating section and heating zone can be controlled separately. In the present invention, the distance between the top heating device and the glass original sheet is greater than the distance between the bottom heating device and the glass original sheet, and accordingly, the top heating temperature of the same heating zone is generally higher than the bottom heating temperature, so as to ensure that the upper and lower surfaces of the glass original sheet are heated evenly.

[0030] The height of each heating zone is denoted as h, and the glass sheet is located on the midline of the height direction of the heating zone. The "top" refers to the area above the glass sheet and whose vertical distance to the glass sheet is greater than 0 and less than or equal to 50% h; the "bottom" refers to the area below the glass sheet and whose vertical distance to 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 respectively controlled to be 560-631°C, for example, it can be 560°C, 562°C, 565°C, 570°C, 580°C, 590°C, 600°C, 610°C, 620°C, 626°C, 629°C, 630°C, 631°C and other specific values, as well as a range with any two of the above specific values ​​as endpoints, and can further be 562-629°C, and can be further controlled to be 565-626°C.

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

[0033] According to a specific embodiment of the present invention, the top heating temperatures of the fourth zone, the fifth zone and the sixth zone may be 606-657°C, respectively. For example, they may be 606°C, 610°C, 620°C, 630°C, 640°C, 650°C, 657°C and other specific values, as well as a range with any two of the above specific values ​​as endpoints, and may further be 608-655°C, and further may be 611-652°C.

[0034] According to a specific embodiment of the present invention, the bottom heating temperatures of the fourth zone, the fifth zone and the sixth zone can be respectively controlled to be 595-650°C, for example, they can be 595°C, 597°C, 600°C, 610°C, 620°C, 630°C, 640°C, 645°C, 648°C, 650°C and other specific values, as well as a range with any two of the above specific values ​​as endpoints, further can be 597-648°C, and further can be 600-645°C.

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

[0036] According to a specific embodiment of the present invention, the bottom heating temperatures of the seventh zone, the eighth zone and the ninth zone can be controlled at 628-670°C, respectively. For example, they can be specific values ​​such as 628°C, 630°C, 640°C, 650°C, 660°C, 670°C, and ranges with any two of the above specific values ​​as endpoints. They can further be 630-668°C, and further 633-665°C.

[0037] In the above-mentioned forming method, heating equipment is respectively provided on the left side, the middle and the right side of the top and bottom of each heating zone. Then each heating zone has a heating temperature of the left side of the top, a heating temperature of the middle of the top, a heating temperature of the right side of the top, a heating temperature of the left side of the bottom, a heating temperature of the middle of the bottom and a heating temperature of the right side of the bottom, and the heating temperatures of the above-mentioned positions can be controlled separately. Among them, the length of a heating zone is d, and "middle" refers to the position of the center line of each heating zone (the center line perpendicular to the transportation direction of the original glass sheet, that is, the center line of the length direction of the heating zone): "left side" refers to the area located on the left side of the center line of the heating zone, and the horizontal distance from the center line is greater than 0 and less than or equal to 30% d; "right side" refers to the area located on the right side of the center line of the heating zone, and the horizontal distance from the center line is greater than 0 and less than or equal to 30% d.

[0038] In some specific embodiments, the heating device may be a heating wire. Specifically, at least a heating wire is provided at the top and bottom of each heating zone; further, heating wires are provided at the top left side, the top middle, the top right side, the bottom left side, the bottom middle, and the bottom right side of each heating zone. The heating temperature at each position of each heating zone may be the temperature of the heating wire.

[0039] The heating furnace of the present invention heats the original glass sheet from the top, bottom, left side, middle and right side of the same heating zone at the same time, which can ensure that all positions of the original glass sheet are heated evenly (including between the upper surface and the lower surface of the original glass sheet, and between the large end, the middle and the small end of the glass). Thus, better microscopic optical performance is achieved, and microscopic optical detection is performed with the help of a refracting plate, a moiré scanner, etc., so as to meet the optical requirements of the automobile windshield. By adopting the above-mentioned heating method and controlling the molding temperature within an appropriate range, the glass can have a moderate viscosity, so that it can flow and form without causing shape instability due to excessive flow, which is conducive to the subsequent pressing and molding stage. The original glass sheet is closely fitted with the concave mold and the convex mold to obtain a better processing effect.

[0040] In the molding method provided by the present invention, the heating temperatures of the front three zones, the middle three zones and the rear three zones are respectively lower than the heating temperatures of the front three zones, the middle three zones and the rear three zones of the existing molding method. By lowering the heating temperature, the optical properties of the molded glass can be significantly improved, especially the microscopic optical properties of the molded glass, for example, the optical distortion can be significantly reduced (the reduction can reach 5-10mdpt). In addition, the present invention can make the curvature of the glass bend just meet the requirements by controlling the average heating temperature of the front three zones, the middle three zones and the rear three zones within a certain range. In some specific embodiments, for the glass original sheet used for the side window glass, the curvature range of the glass original sheet after heating treatment can meet the following requirements: the curvature radius ≥ 1000mm; for the glass original sheet used for the front windshield glass, the curvature range of the glass after heating treatment can meet the following requirements: the curvature radius is 200-3000mm.

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

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

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

[0044] In the above molding method, the bottom heating temperature of the first zone is 548-592°C, further can be 550-590°C, and further can be 553-587°C.

[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 further can be 574-610°C.

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

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

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

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

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

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

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

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

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

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

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

[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 raw sheet molding method.

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

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

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

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

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

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

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

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

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

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

[0068] According to a specific embodiment of the present invention, in the first to ninth zones, the length of each heating zone is generally 1500-4000 mm. Among them, the first to eighth zones are usually used as heating zones, and their main functions are to heat the original glass sheet (the first to seventh zones) and keep it warm (the eighth zone); the ninth zone is used as a heating transmission zone, in addition to maintaining the heating temperature of the original glass sheet (similar to or basically the same as the heating temperature of the eighth zone), it is also used to transport the original glass sheet to the forming section. Correspondingly, the transmission speed of the glass sheet in the first zone to the eighth zone can be 50-300mm / s, for example, 50mm / s, 100mm / s, 150mm / s, 200mm / s, 250mm / s, 300mm / s and other specific values, 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 800-1500mm / s, for example, 800mm / s, 900mm / s, 1000mm / s, 1100mm / s, 1200mm / s, 1300mm / s, 1400mm / s, 1500mm / s and other specific values, and a range with any two of the above specific values ​​as endpoints. In a specific embodiment, 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 glass sheet with a thicker thickness, it can be transmitted at a lower transmission speed 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 press molding process may include: sending the heated glass sheet to a molding 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, and the glass sheet contacts the concave mold and the convex mold at the same time and is pressed; after the pressing is completed, the convex mold sucks the glass sheet up, and then the transmission shuttle of the molding section extends to the bottom of the convex mold and the glass sheet, and after the travel of the transmission shuttle is in place, the convex mold and the glass sheet are separated, and the glass sheet falls on the transmission shuttle and is transmitted by the transmission shuttle to the annealing area for annealing to complete the press molding.

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

[0071] In the above molding process, the convex mold in the molding section is located above the original glass sheet and has an arc-shaped surface, which can contact the entire upper surface of the original glass sheet. Furthermore, the surface of the convex mold can have a plurality of (more than two) small holes regularly distributed, and the aperture of the small holes is generally less than 5 mm. Through the above small holes, the convex mold can vacuum absorb the original glass sheet and move it.

[0072] In the above-mentioned pressing process, the time when the glass sheet is in contact with the concave mold and the convex mold at the same time (i.e., the molds are closed) is the pressing time, and the pressing time is generally less than 2 seconds.

[0073] The present invention also provides a low-absorption and high-transmittance (SuperClear, SC for short) glass, which is obtained by forming by the above 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 ≤150mdpt; the tensile stress of the low-absorption high-transmittance glass and / or the laminated glass made of the low-absorption high-transmittance glass is <12MPa, 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 >12MPa. The laminated glass may include two layers of the above-mentioned low-absorption high-transmittance glass, with an adhesive layer such as PVB (polyvinyl butyral) sandwiched between the two glass plates.

[0075] In some specific embodiments, the refractive index, conformity and other parameters of the laminated glass made of the low-absorption and high-transmittance glass meet the requirements of GB9656-2003 "Automobile Safety Glass".

[0076] In some specific embodiments, the transmittance of the glass sheet for light with a wavelength of 800-1600nm is 90% or more, and can further reach 91% or more. The low-absorption and high-transmittance glass made by the molding method of the present invention using the glass sheet also maintains the above transmittance. The transmittance of the low-absorption and high-transmittance glass for light with a wavelength of 800-1600nm can reach 90% or more, and can further reach 91% or more, and can further reach 91.2% or more.

[0077] In some specific embodiments, the light absorption coefficient of the glass substrate for light with a wavelength of 800-1600 nm is 0.04-0.2 cm -1 , can further reach 0.04-0.1cm -1The low-absorption and high-transmittance glass made by the molding method of the present invention using the original glass sheet can also maintain the low-absorption performance. The light absorption coefficient of the low-absorption and high-transmittance glass for light with a wavelength of 800-1600nm is 0.04-0.2cm -1 , can further reach 0.04-0.1cm -1 .

[0078] The present invention also provides a vehicle window glass, which is made of the above-mentioned low-absorption and high-transmittance glass. In some specific embodiments, the vehicle window glass can be a front windshield, a rear windshield, a side window glass, a skylight glass, a corner window glass, etc. The low-absorption and high-transmittance glass provided by the present invention has a high optical transmittance in the near-infrared band, which can meet the requirements of optical sensors such as LiDAR and infrared cameras for glass transmittance, and can be used to make functional integrated vehicle window glass, such as a functional integrated front windshield.

[0079] The beneficial effects of the present invention include:

[0080] The low-absorption and high-transmittance glass provided by the present invention has a low molding temperature, low absorption and high light transmittance, especially high optical transmittance in the 800-1600nm optical band. The low-absorption and high-transmittance glass can meet the requirements of optical sensors for light transmittance and can be used for functional integrated glass, such as the front windshield of LiDAR built-in products. DETAILED DESCRIPTION

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

[0082] In the following experiments, the glass sheets used are from the ultra-white glass series of Shandong Jinjing Technology Co., Ltd.

[0083] Example 1

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

[0085] S1, sending the original glass sheet into a heating furnace for heating treatment;

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

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

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

[0089] The heating furnace is equipped with a preheating section, a heating section and a constant temperature gradient section. Specifically, there are 9 heating zones in the heating furnace. The original glass sheet is conveyed from left to right. The heating zones are the first zone, the second zone, the third zone, the fourth zone, the fifth zone, the sixth zone, the seventh zone, the eighth zone and the ninth zone from left to right. The heating temperature of the first zone to the ninth zone gradually increases. Among them, the first zone to the third zone are the preheating section, the fourth zone to the seventh zone are the heating section, and the eighth zone and the ninth zone are the constant temperature gradient section.

[0090] The top and bottom of each heating zone are respectively provided with heating furnace wires 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 provided at the left, middle and right sides of the same height. That is, each heating zone is provided with heating wires at the left side of the top, the middle of the top, the right side of the top, the left side of the bottom, the middle of the bottom and the right side of the bottom. The temperature of each heating wire is independently controlled, and the heating wires of each heating zone can heat the original glass sheet at the same time. At the same height of the same heating zone, the heating temperature gradually increases from left to right.

[0092] Among them, the height of each heating zone is denoted as h, the glass sheet is located on the midline of the height direction of the heating zone, the "top" refers to the area above the glass sheet, and the vertical distance to the glass sheet is greater than 0 and less than or equal to 50% h; the "bottom" refers to the area below the glass sheet, and the vertical distance to 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, and the corresponding area ranges of the middle, left and right sides at the same height are as follows: "middle" refers to the area located on the midline of the length direction of the heating zone, "left side" refers to the area located on the left side of the midline in the length direction, and the horizontal distance from the midline is greater than 0 and less than or equal to 30% d; "right side" refers to the area located on the right side of the midline in the length direction, and the horizontal distance from the midline is greater than 0 and less than or equal to 30% d.

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

[0095] The molding section for performing press molding in S2 includes a punch, a die, and a transfer shuttle.

[0096] The convex mold is located above the original glass sheet and has an arc-shaped surface that can contact the entire upper surface of the original glass sheet. The surface of the convex mold may have a number (more than two) of small holes regularly distributed, and the aperture of the small holes is generally less than 5 mm. Through the above-mentioned small holes, the convex mold can vacuum absorb the original glass sheet to make it move.

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

[0098] The pressing process of S2 specifically includes: 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 at the same time (i.e., the molds are closed) and pressed, the pressing temperature is controlled to be lower than the heating temperature of the fourth to ninth zones in the heating furnace, and the pressing time is controlled to be less than 2 seconds; after the pressing is completed, the convex mold sucks the glass sheet to form an upward movement, and then the transmission shuttle extends to the bottom of the convex mold and the glass sheet. After the travel of the transmission shuttle is in place, the convex mold and the glass sheet are separated, and the glass sheet falls on the transmission shuttle and is transmitted by the transmission shuttle to the annealing area for annealing (annealing temperature is 500-600℃, annealing time is 10-30min), completing the pressing and molding.

[0099] Comparative Example 1

[0100] This comparative example provides a method for forming a green glass raw sheet, which includes sending the green glass raw sheet into a heating furnace for heating treatment, and then sending it to a forming section for press forming after it is output from the heating furnace to obtain green glass, which is recorded as G glass.

[0101] The glass sheet used in this comparative example is a green glass sheet, the iron content of the glass sheet is 800ppm-900ppm, the softening point of the glass sheet is 725-730°C, the annealing point is 560-620°C, and 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 furnace wires are also the same as those in Example 1.

[0103] The heating temperatures at each position of each heating zone are shown in Table 1 (the numerical unit in the table is °C). "Upper left" represents the heating temperature of the left side of the top, "Upper middle" represents the heating temperature of the middle of the top, "Upper right" represents the heating temperature of the right side of the top, "Lower left" represents the heating temperature of the left side of the bottom, "Lower middle" represents the heating temperature of the middle of the bottom, and "Lower right" represents the heating temperature of the right side of the bottom. The temperatures in Table 1 are the readings of the thermocouple temperatures.

[0104] Table 1

[0105]

[0106] It can be seen from Table 1 that the molding temperature of the existing green glass raw sheet molding method is 576-658° C., while the molding temperature of the low-absorption and high-transmittance glass raw sheet molding method of the present invention is 553-643° C. The molding method provided by the present invention has a lower temperature.

[0107] Example 2

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

[0109] S1, sending the original glass sheet into a heating furnace for heating treatment;

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

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

[0112] The molding method of this embodiment is similar to the molding method of embodiment 1, except that the temperature of the heating treatment in S1 is different. The heating temperatures of each position 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 raw sheet, which includes sending the green glass raw sheet into a heating furnace for heating treatment, and then sending it to a forming section for press forming after it is output from the heating furnace to obtain green glass, which is recorded as G glass.

[0115] The glass sheet used in this comparative example is a green glass sheet, the iron content of the glass sheet is 800ppm-900ppm, the softening point of the glass sheet is 725-730°C, the annealing point is 560-620°C, and 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 furnace wires are also the same as those in Example 2.

[0117] The heating temperature at each position of each heating zone is shown in Table 2 (G sample). The numerical unit in Table 2 is ° C. The temperature in Table 2 is the reading of the thermocouple temperature.

[0118] Table 2

[0119]

[0120]

[0121] It can be seen from Table 2 that when the thickness of the glass sheet is adjusted to 6 mm, the molding temperature of the existing green glass sheet molding method is 596-678° C., while the molding temperature of the low-absorption and high-transmittance glass sheet molding method of the present invention is 578-669° C. In comparison, the heating temperature of the molding method provided by the present invention is lower.

[0122] Test Example 1

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

[0124]

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

[0126] The low-absorption and high-transmittance glass sheet 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 .

[0127] The green glass raw sheet used in the molding method of Comparative Example 1 has an iron content of 805 ppm, a softening point of 728°C, an annealing point of 592°C, and a light absorption coefficient of 3.76 cm -1 .

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

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

[0130] In addition, the laminated glass made of the SC glass of Example 1 and Example 2 was tested for optical distortion, tensile stress, edge compressive stress, refraction, fit, etc. The laminated glass consists of two SC glasses and a 0.76 mm thick PVB adhesive layer, and the PVB adhesive layer is located between the two glass plates.

[0131] It was measured that the laminated glass made of low-absorption and high-transmittance glass in Example 1 had the following properties: optical distortion was 129mdpt; tensile stress was 10.5MPa, and edge compressive stress was 13.1MPa; the optical distortion of the laminated glass made of low-absorption and high-transmittance glass in Example 2 was 148mdpt; tensile stress was 11.2MPa, and edge compressive stress was 15.3MPa.

[0132] The refraction, conformity and other properties of the laminated glass made of the SC glass of Example 1 and Example 2 all meet the requirements of GB9656-2003 "Automobile Safety Glass".

[0133] It can be seen from the above results that the transmittance of existing glass in the near-infrared light band is relatively low, and it is difficult to meet the requirements of optical sensor components for the optical properties of glass; while the low-absorption and high-transmittance glass made by the above-mentioned molding method provided by the present invention can have an optical transmittance of more than 91% in the near-infrared light band, which can meet the requirements of sensors such as LiDAR for optical transmittance, and can be used to prepare functional integrated front windshields and other vehicle window glasses.

Claims

1. A method for forming low-absorption and high-transmittance glass, the method comprising: Placing the original glass sheet in a heating furnace for heating treatment, and then pressing and molding to obtain the low-absorption and high-transmittance glass; The heating furnace comprises 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°C, the outlet temperature of the preheating section is 571-631°C, and the outlet temperature of the preheating section is higher than the inlet temperature; The inlet temperature of the heating section is 595-646°C, the outlet temperature of the heating section is 628-673°C, and the outlet temperature of the heating section is higher than the inlet temperature; The temperature of the constant temperature gradient section is 628-674°C; 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°C.

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

3. The molding method according to claim 1 or 2, wherein: The heating furnace has 9 heating zones, which are the first zone to the ninth zone from the sheet inlet to the sheet outlet of the heating furnace, the first zone to the third zone are preheating sections, the fourth zone to the seventh zone are heating sections, and the eighth zone to the ninth zone are constant temperature gradient sections; From the first zone to the ninth zone, the heating temperature gradually increases; each heating zone heats the original glass sheet from above and below at the same time; Among them, the heating temperatures of the first zone, the second zone and the third zone are 548-631°C respectively, the heating temperatures of the fourth zone, the fifth zone and the sixth zone are 595-657°C respectively, and the heating temperatures of the seventh zone, the eighth zone and the ninth zone are 628-674°C respectively.

4. The molding method according to claim 3, wherein: The top heating temperature of the same heating zone is higher than the bottom heating temperature; The top heating temperatures of the first zone, the second zone and the third zone are 560-631°C, respectively, and the bottom heating temperatures of the first zone, the second zone and the third zone are 548-617°C, respectively; The top heating temperatures of the fourth zone, the fifth zone and the sixth zone are 606-657° C., respectively, and the bottom heating temperatures of the fourth zone, the fifth zone and the sixth zone are 595-650° C., respectively; The top heating temperatures of the seventh zone, the eighth zone and the ninth zone are 633-674°C, respectively, and the bottom heating temperatures of the seventh zone, the eighth zone and the ninth zone are 628-670°C, respectively.

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

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

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

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

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

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

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

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

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

14. The molding method according to claim 3, wherein: In the first to ninth zones, the length of each heating zone is 1500-4000 mm; The original glass sheet is uniformly transported in the first zone to the eighth zone, and the transport speed is 50-300 mm / s; The original glass sheet is uniformly transported in the ninth zone, and the transport speed is 800-1500 mm / s.

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

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

17. A low-absorption and high-transmittance glass obtained by molding using the molding method according to any one of claims 1 to 16.

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

19. The low-absorption and high-transmittance glass according to claim 17, wherein: The transmittance of the low-absorption and high-transmittance glass to light with a wavelength of 800-1600 nm is above 90%.

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

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