Glass plate with identification mark and method for manufacturing glass plate with identification mark

Abstract

This method for manufacturing a glass plate with an identification mark includes forming an identification mark on a main surface of a glass plate by irradiating the main surface with UV laser light.

Description

[Technical Field]

[0001] The present invention relates to a glass plate provided with an identification mark and a method for manufacturing a glass plate provided with an identification mark. [Background technology]

[0002] One known method for applying an identification mark indicating a standard, product name, manufacturer, etc. to a glass plate is to partially roughen the surface of the glass plate. For example, Patent Document 1 describes forming a roughened surface on one main surface of the glass plate by a shot blasting method (sandblasting method) in which abrasive sand is blasted onto the surface. This allows the identification mark to be formed by expressing a predetermined design through the contrast between the roughened surface and the remaining portion. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-48110 Summary of the Invention [Problem to be solved by the invention]

[0004] In the sandblasting method described in Patent Document 1, a stencil plate (mask) with cutouts corresponding to the roughened surface is placed on the main surface of the glass, and then abrasive sand is blasted onto it to roughen the cutout areas not covered by the stencil plate. Here, if the design of the identification mark includes a continuous ring, it becomes necessary to use multiple separate stencil plates to form a single design. However, it is difficult to accurately position such separate stencil plates relative to one another to create the desired mark.

[0005] In recent years, the design of identification marks has become more complex, and there is an increasing demand for marks to be formed with designs that include minute or thin roughened portions. However, in conventional methods using sandblasting, there is a limit to how much the diameter of the abrasive sand can be minimized, and it is sometimes not possible to roughen minute areas, resulting in unclear marks.

[0006] Therefore, an object of one aspect of the present invention is to provide a method for producing a glass plate with an identification mark, which can apply a more accurate and clearer identification mark to the glass plate. [Means for solving the problem]

[0007] One aspect of the present invention is a method for producing a glass plate having an identification mark, which includes forming an identification mark by irradiating a main surface of the glass plate with UV laser light. [Effects of the Invention]

[0008] According to one aspect of the present invention, it is possible to provide a method for producing a glass plate provided with an identification mark, which can provide a more accurate and clearer identification mark on the glass plate. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram of an apparatus for manufacturing a glass plate provided with an identification mark according to an embodiment of the present invention. [Figure 2] 1A and 1B are diagrams showing an example of an identification mark and a partially enlarged view thereof; [Figure 3] 1 is an electron microscope photograph of a portion of the identification marks formed in Examples 1 to 3. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each drawing, unless otherwise specified, the same or corresponding components will be designated by the same reference numerals and their description may be omitted. Furthermore, the drawings are schematic to aid in understanding the invention, and the scales in the drawings may differ from the actual scales.

[0011] Fig. 1(a) is a schematic diagram of a manufacturing apparatus used in a manufacturing method of a glass plate 100 provided with an identification mark according to this embodiment. As shown in Fig. 1(a), in this embodiment, an identification mark 20 is formed by irradiating a main surface of a glass plate 10 with UV laser light 3 emitted from a laser light generating unit 2 in a UV laser light generating device 1.

[0012] The identification mark 20 is a mark for displaying information about the production and / or quality of the glass sheet on the glass sheet. More specifically, it is a mark that displays one or more of the following: the manufacturer, product name, product number, model number, production date, processing conditions or inspection conditions, and certification under standards such as JIS or ISO. The identification mark 20 may be a letter, number, figure, logo, etc., or a combination of two or more of these. Furthermore, the identification mark may include a mark primarily intended for decoration rather than for displaying specific information. The schematic diagram of FIG. 1(a) shows an example of the letter A formed as the identification mark 20, and FIG. 1(b) shows an enlarged view of the identification mark 20.

[0013] The position on the main surface of the glass plate 10 where the identification mark 20 is provided is not particularly limited, but when the glass plate 100 with an identification mark is used as a window, the identification mark 20 is preferably provided in a position that does not obstruct the field of view of users or passengers. More specifically, the identification mark 20 is preferably provided in a predetermined position near the periphery of the glass plate, and more preferably near the horizontal and / or vertical edges of the glass plate when it is attached to a vehicle, building, etc. For example, in the case of a substantially rectangular glass plate, the identification mark 20 is preferably formed at and / or near a corner of the glass plate 10, as shown in FIG. 1(a).

[0014] The glass plate 10 to which the identification mark 20 is attached may be inorganic glass, more specifically, soda-lime silicate glass, aluminosilicate glass, borate glass, lithium aluminosilicate glass, borosilicate glass, or the like. The glass plate 10 may be untempered glass or tempered glass that has been subjected to an air-cooling tempering process or a chemically tempered process. Untempered glass is produced by forming molten glass into a plate shape and slowly cooling it. Tempered glass is produced by forming a compressive stress layer on the surface of untempered glass, and may be physically tempered glass (e.g., air-cooled tempered glass) or chemically tempered glass. In the case of air-cooled tempered glass, the glass surface may be strengthened by rapidly cooling a uniformly heated glass plate from a temperature near its softening point, thereby generating compressive stress on the glass surface due to the temperature difference between the glass surface and the interior of the glass. In the case of chemically tempered glass, the glass surface may be strengthened by generating compressive stress on the glass surface using an ion exchange method or the like.

[0015] The glass plate 10 is transparent, and the visible light transmittance of the glass plate 10 measured by a measurement method in accordance with JIS R 3106:1998 may be preferably 70% or less, more preferably 60% or less. The glass plate 10 may be colored to an extent that does not impair transparency. When the glass plate 10 is colored, the color and intensity are not particularly limited as long as ultraviolet light can be absorbed at least in the region where the identification mark 20 is applied.

[0016] The thickness of the glass plate 10 may be 0.2 to 5 mm, preferably 0.3 to 2.4 mm. When the glass plate 10 is laminated with another glass plate to form laminated glass and the glass plate 10 is disposed on the exterior side of the vehicle, the thickness of the glass plate 10 is preferably 1.1 to 3 mm at its thinnest portion. When the thickness of the glass plate disposed on the exterior side of the vehicle is 1.1 mm or more, the strength required for resistance to flying stones and the like is sufficient, and when the thickness is 3 mm or less, the weight of the laminated glass is not too large, which is preferable in terms of fuel efficiency of the vehicle. The thickness of the glass plate disposed on the exterior side of the vehicle is preferably 1.8 to 2.8 mm at its thinnest portion, more preferably 1.8 to 2.6 mm, even more preferably 1.8 to 2.2 mm, and even more preferably 1.8 to 2.0 mm. When the glass plate 10 is laminated with another glass plate to form laminated glass and the glass plate 10 is disposed on the interior side of the vehicle, the thickness of the glass plate 10 is preferably 0.3 to 2.3 mm. The thickness of the glass panels located on the inside of the vehicle is 0.3 mm or more, making them easy to handle, and 2.3 mm or less, so the weight does not become too large.

[0017] The glass plate 100 with an identification mark manufactured by the method of this embodiment may have a single-curve shape, bent in only one direction, for example, only in the left-right or up-down direction of the automobile when attached to an opening in the automobile. The glass plate with an identification mark may also have a compound-curve shape, bent in both the left-right and up-down directions. The bending may be gravity forming, press forming, or the like. Such bending may be performed after forming an identification mark on the glass plate, or the glass plate may be bent after production, and the identification mark may be formed on the main surface using a UV laser. When the glass plate with an identification mark is bent to a predetermined curvature, the radius of curvature of the glass plate may be 1,000 to 100,000 mm.

[0018] The glass plate 100 with an identification mark manufactured according to this embodiment is suitable for use as vehicle glass, for example, window glass such as a windshield, rear glass, side glass, or roof glass. The glass plate 100 with an identification mark may also be used as glass for building materials. The glass plate with an identification mark may be laminated with another glass plate via an interlayer film such as a thermoplastic resin to form laminated glass. In this case, the laminated glass may be formed after the identification mark is formed on the glass plate, or the identification mark may be formed after the laminated glass is formed.

[0019] Furthermore, when the glass plate 100 with an identification mark manufactured according to this embodiment is used as a vehicle window, a shielding layer (also called black ceramic) may be provided along the peripheral edge of the glass plate 100 with an identification mark. The shielding layer is a layer that functions to protect sealants and the like that adhere and hold the vehicle glass plate to the vehicle body, and can be formed by applying and baking a paste containing a dark pigment and glass powder. It is preferable that the identification mark is formed in a position that does not overlap the shielding layer. The shielding layer can be provided after the identification mark 20 is formed on the glass plate.

[0020] The glass plate 10 may be entirely coated on one or both of its main surfaces with a coating layer for blocking ultraviolet rays, blocking infrared rays, providing anti-fogging properties, or for providing other functions. The identification mark 20 may be formed by irradiating the surface of the glass plate 10 that is covered with a coating layer with UV laser light. However, it is preferable that the glass plate 10 has no coating layer at least on the portion where the identification mark 20 is to be formed, or on at least the main surface on which the identification mark 20 is to be formed, so that the glass surface is exposed and the identification mark 20 is formed on the uncoated main surface.

[0021] In the method of this embodiment, UV laser light 3 is irradiated to scrape or inscribe the surface layer of the main surface of the glass plate 10, thereby forming an area containing fine irregularities (roughened area), and forming the identification mark 20. Therefore, compared to methods in which a colorant layer or the like is added by printing or the like, the visibility of the identification mark once formed is less likely to be lost. In other words, the added layer will not peel off in subsequent processing steps or when the glass plate is used, and the shape of the identification mark can be maintained.

[0022] The UV laser beam generator (or UV laser marker) 1 used may be a scanning type. More specifically, it is preferable that the UV laser beam 3 can scan at least along the surface direction of the main surface of the glass plate 10 (capable of biaxial scanning). In this case, the position of the glass plate 10 may be fixed and the laser beam generator 1 may be movable in a direction along the main surface of the glass plate 10, or the position of the laser beam generator 1 may be fixed and the glass plate 10 may be movable in a direction along the main surface. Furthermore, the direction in which the UV laser beam 3 is irradiated onto the glass plate 10 is not particularly limited, but it is preferable that the UV laser beam 3 be irradiated perpendicularly onto the glass plate 10.

[0023] In this manner, in this embodiment, the roughened area constituting the design of the identification mark 20 can be formed by scanning the surface of the glass plate 10 with UV laser light, so that continuous circular or closed linear designs can be easily drawn. For example, when attempting to draw the letter A as shown in FIG. 1(b) using the roughened area 22, the upper part of the letter A has a continuous triangular circular portion. Designs including such portions can also be formed by scanning the laser light. Therefore, the method using a UV laser according to this embodiment can more accurately form identification marks with designs that are difficult to form using sandblasting methods, which require stencil plates or the like. Furthermore, identification marks with complex designs expressed by roughening minute areas or thin linear areas can be more clearly formed.

[0024] The wavelength of the laser light used in this embodiment may be in the ultraviolet range, i.e., 400 nm or less, preferably 380 nm or less, and more preferably 360 nm or less. The lower limit of the wavelength is not particularly limited, but may be 10 nm or more, preferably 100 nm or more. At wavelengths in the ultraviolet range, the laser light has a high absorptivity in glass, allowing glass plates to be processed well. In particular, at wavelengths of 360 nm or less, absorption is observed in many colored glass plates, making it possible to accommodate various glass forms.

[0025] Furthermore, because the laser beam has a wavelength in the ultraviolet range, the spot diameter of the laser beam (the diameter of the laser beam when irradiated directly onto the surface of the glass plate) can be reduced, allowing narrow grooves to be formed by scanning the laser beam. By forming multiple narrow grooves spaced apart from one another through scanning the laser beam, fine irregularities can be formed within the roughened area, and the fine diffused reflections can be dispersed throughout the roughened area, giving the visual impression that the entire roughened area is uniformly filled in (sometimes referred to as a uniform texture). This enhances the aesthetic appeal of the roughened area. Furthermore, the visual contrast between the roughened area and the untreated, non-roughened area can be increased, making the identification mark 20 more visible.

[0026] Furthermore, with wavelengths in the ultraviolet range, the photon energy in the laser light is high, so less heat is generated during processing. Therefore, even when glass is irradiated with laser light of a wavelength in the ultraviolet range, cracks and other defects are unlikely to occur in the glass. Because cracks occur irregularly, depending on the size and depth of the cracks, they can be visually perceived as an irregular scale-like pattern, reducing the uniformity of the roughened area. The contours of the roughened area can also become unclear. In contrast, by reducing or preventing the occurrence of cracks and other defects in the glass according to this embodiment, the uniformity is improved, resulting in an identification mark with higher visibility and aesthetic appeal. Furthermore, a decrease in the strength of the glass plate 10 due to the occurrence of cracks and other defects can be prevented.

[0027] The method of generating the laser light is not particularly limited as long as the wavelength of the light ultimately irradiated onto the glass plate 10 is in the ultraviolet range, and any of a solid-state laser, a gas laser, and a liquid laser may be used. For example, the UV laser light may be a higher-order harmonic obtained by wavelength conversion of light of a fundamental wavelength wave. Specific examples include the third and fourth harmonics of solid-state lasers such as Nd:YVO4 lasers and Nd:YAG lasers. The UV laser light may be a continuous wave (CW) or a pulsed wave. In the case of a pulsed wave, the influence of heat can be further reduced, further preventing cracks and the like from occurring in the glass plate 10.

[0028] As described above, the identification mark 20 can be expressed by the roughened region 22 ( FIG. 1( b) ) and the visual contrast between the roughened region 22 and the remaining untreated region, i.e., the contrast in transparency or reflectance. In other words, at least a portion of the identification mark 20 has a roughened region 22 in which at least a portion of the surface of the glass plate 10 is roughened. The roughened region 22 has a plurality of grooves formed therein that are spaced apart from one another throughout its entirety, and therefore the transparency of the roughened region 22 is lower than the transparency of the remaining untreated region.

[0029] In the manufacturing method according to this embodiment, in the step of forming the identification mark 20, it is preferable to irradiate the UV laser light so as to form a plurality of grooves (long, narrow recesses in plan view) spaced apart in a predetermined direction. In other words, it is preferable that the roughened region 22 be formed by an aggregate of a plurality of grooves. The plurality of grooves spaced apart in a predetermined direction can be formed, for example, by scanning and irradiating the laser light in a direction perpendicular to the predetermined direction, then moving the laser light generator 2 in the predetermined direction, and again scanning and irradiating the laser light in a direction perpendicular to the predetermined direction. This can be done by repeating this process. Note that the grooves in this embodiment include grooves that can be observed with the naked eye, as well as grooves that can be observed under magnification with a microscope, magnifying glass, or the like, for example, at a magnification of 200 times.

[0030] FIG. 2(a) shows an identification mark 20 with a different design from that shown in FIG. 1, and FIG. 2(b) shows an enlarged view of portion II of FIG. 2(a). In this embodiment, by scanning the laser beam as described above, a collection of multiple grooves 25 as shown in FIG. 2(b) can be formed in the roughened region 22. More specifically, by scanning the laser beam along the scanning direction D1, the grooves formed along the scanning direction D1 can form grooves 25a, 25a, ... spaced apart in an orthogonal direction D2 perpendicular to the scanning direction D1. Because the original surface level (height) of the glass plate 10 is maintained in the areas between the grooves 25a, the roughened region 22 can have a microstructure in which elongated depressions and protrusions (grooves and ridges) are repeated when viewed along the orthogonal direction D2. In such a structure, the light reflection characteristics change microscopically and regularly along the orthogonal direction D2, and therefore, when viewed with the naked eye, it can be observed as a regular, fine stripe pattern or a homogeneous region that appears to be colored in a single color. The scanning direction D1 is the same as the extension direction of the formed grooves 25a.

[0031] 2(b), grooves 25a are formed as continuous lines extending from one position on the contour of roughened region 22 to another position on the contour opposite to that one position, but grooves 25a may be discontinuous along the way. However, it is preferable to irradiate with UV laser light so that each groove 25a becomes a continuous groove from one position on the contour to another position on the opposing contour, because this makes it easier for the observer to see that roughened region 22 is uniform in appearance.

[0032] 2(b), grooves 25b can be formed in the roughened region 22 along the contour of the roughened region 22. By forming the grooves 25b, the design of the identification mark 20 becomes clearer.

[0033] The grooves 25 can be formed by irradiating the glass plate 10 with UV laser light at a spot diameter of 5 to 50 μm, preferably 15 to 40 μm. A spot diameter of 10 μm or greater allows for wider and deeper grooves to be formed in the roughened region 22, thereby promoting diffuse reflection in the roughened region 22 and reducing transparency. Furthermore, a spot diameter of 40 μm or less reduces heat that may be generated and remain in the glass plate 10 due to the laser light, thereby preventing cracks and the like from occurring in the glass plate 10. By adjusting the spot diameter within the above range, the width w of the formed grooves 25 can be 5 to 40 μm, preferably 10 to 30 μm. The groove width w can be determined by analyzing a planar image, for example.

[0034] In this embodiment, one groove 25 can be formed by one scan or by overlapping multiple scans, but from the viewpoint of reducing the influence of heat and preventing cracks and the like from occurring in the glass plate, it is preferable to form one groove 25 by one scan. Also, from the same viewpoint, it is preferable that the grooves 25 do not overlap or barely overlap each other.

[0035] In forming the plurality of grooves 25, the spot diameter of the irradiated UV laser light may be the same or may be changed during the formation process. When the spot diameter is changed, for example, the spot diameter may be changed during the formation of one groove 25, or the spot diameter of the irradiated UV laser light may be changed depending on the groove 25 to be formed. Furthermore, the spot diameter may be the same or different between the process of forming groove 25a and the process of forming groove 25b.

[0036] Similarly, the width of the formed grooves 25 may or may not be uniform within the roughened region 22. If the width is not uniform, for example, the width may vary within one groove 25, or the width may differ depending on the groove 25. Furthermore, the width of groove 25a and the width of groove 25b may be the same or different.

[0037] Furthermore, the pitch p of the multiple grooves 25a, 25a, ... formed at intervals in the orthogonal direction D2 perpendicular to the scanning direction D1, i.e., the minimum distance between the center line of one groove 25a and the center line of an adjacent groove 25a, may be greater than the width w of the groove 25a. Furthermore, as shown in Fig. 2, the pitch p may be the distance along the orthogonal direction D2 from an edge on one side of one groove 25a in the orthogonal direction D2 to the edge on the same side of the adjacent groove 25a. Furthermore, the pitch p may be preferably 3 μm or more, more preferably 7.5 μm or more, even more preferably 10 μm or more, even more preferably 40 μm or more, even more preferably 50 μm or more, and even more preferably 70 μm or more, and may be preferably 1000 μm or less, more preferably 500 μm or less, even more preferably 200 μm or less, even more preferably 150 μm or less, even more preferably 130 μm or less, and even more preferably 100 μm or less. Furthermore, when the pitch p varies within the roughened region 22 of the identification mark 20, the average value of the pitch p may be preferably 50 to 150 μm, more preferably 70 to 130 μm. The pitch p can be determined by analyzing a planar image, etc.

[0038] By setting the pitch p of the grooves 25a to 3 μm or more, the amount of heat generated per unit area in the glass plate can be reduced, preventing cracks and other damage to the glass plate. Furthermore, considering the minimum beam diameter of the UV laser light generating unit in the marking device, a pitch p of 7.5 μm or more is preferable. On the other hand, by setting the pitch p of the grooves 25a to 1000 μm or less, particularly 200 μm or less, the spacing between the grooves can be prevented from becoming too wide. This prevents the transparency of the roughened region 22 from approaching that of the untreated region, reducing the contrast between the roughened region 22 and the untreated region, and also prevents the grooves 25 from becoming too localized, impairing the uniform texture within the roughened region 22.

[0039] The pitch p of grooves 25a may be the same or different within roughened region 22. Furthermore, grooves 25a are preferably formed parallel to one another, but may be formed at an angle within ±10° from strict parallelism.

[0040] The pitch p between the grooves 25a spaced apart in the orthogonal direction D2 in the identification mark 20 can be obtained by setting or controlling the scanning pitch of the UV laser light generator when forming the grooves 25a, i.e., the distance by which the UV laser light generator is moved along the orthogonal direction D2 to form the next groove after scanning along the scanning direction D1 to form a groove. Therefore, the scanning pitch of the UV laser light generator can be set to preferably 3 μm or more, more preferably 7.5 μm or more, even more preferably 10 μm or more, even more preferably 40 μm or more, even more preferably 50 μm or more, even more preferably 70 μm or more, and preferably 1000 μm or less, more preferably 500 μm or less, even more preferably 200 μm or less, even more preferably 150 μm or less, even more preferably 130 μm or less, and even more preferably 100 μm or less. The scanning pitch may be constant throughout the formation of a single identification mark, or may be set to vary. The pitch p between the formed grooves 25a is roughly the same value or range of values as the scanning pitch set by the marking device, but can be 0.85 to 1.15 times the scanning pitch depending on the type of glass plate, conditions for applying the identification mark, and other conditions.

[0041] As described above, when forming the grooves 25, the UV laser light is scanned over the glass plate. The scanning speed of the UV laser light may be preferably 20 to 1200 mm / sec, more preferably 80 to 250 mm / sec, and even more preferably 80 to 160 mm / sec. A scanning speed of 20 mm / sec or more can reduce the thermal effect of the laser light on the glass plate, preventing cracks and the like from occurring in the glass plate. Processing efficiency can also be improved. A scanning speed of 1200 mm / sec or less can form grooves 25 having a certain width or more and / or a certain depth or more in the roughened region 22, i.e., portions with reflection characteristics different from those of the untreated region.

[0042] Furthermore, the work distance (the distance from the laser emission surface to the main surface of the glass plate) when irradiating the UV laser light can be set to preferably 150 to 230 mm, more preferably 165 to 215 mm.

[0043] To form grooves 25a in roughened region 22, the laser beam can be scanned linearly or linearly, but linear scanning improves irradiation efficiency and prevents the work from becoming complicated. Furthermore, in the resulting roughened region 22, multiple grooves 25a spaced apart in orthogonal direction D2 each extend linearly, thereby improving the uniformity of roughened region 22.

[0044] When the laser beam is oscillated as a pulse wave, the energy density of the irradiated laser beam is preferably 100 to 50,000 kJ / m 2 , more preferably 250 to 2500 kJ / m 2 The frequency may be preferably 20 to 60 kHz, more preferably 40 to 50 Hz. When the laser beam is oscillated as a continuous wave, the energy density of the irradiated laser beam is preferably 100 to 50,000 kJ / m 2 , more preferably 250 to 2500 kJ / m 2 It may be.

[0045] The resulting identification mark 20 may have predetermined surface roughness characteristics in the roughened region 22. For example, the first arithmetic mean roughness Ra1 of the grooves measured along the groove extension direction (laser light scanning direction) D1 is preferably 1.5 to 3.0 μm, and more preferably 1.8 to 2.2 μm. The second arithmetic mean roughness Ra2 measured along the orthogonal direction D2 perpendicular to the groove extension direction D1 is preferably 1.5 to 3.0 μm, and more preferably 1.8 to 2.2 μm.

[0046] Furthermore, the first maximum height Rz1 of the groove measured along the groove extension direction D1 is preferably 10 to 40 μm, and more preferably 15 to 30 μm. The second maximum height Rz2 measured along the orthogonal direction D2 perpendicular to the groove extension direction D1 is preferably 10 to 50 μm, and more preferably 10 to 40 μm. Furthermore, the ratio of the second maximum height Rz2 to the first maximum height Rz1 (Rz2 / Rz1) is preferably 1 to 2, and more preferably 1.2 to 1.8.

[0047] The average length RSm2 of the roughness curve elements measured along the direction D2 perpendicular to the groove extending direction D1 can be preferably 50 to 150 μm, more preferably 70 to 130 μm. A mark with RSm2 of 50 μm or more has a high aesthetic appeal because the heat generated during groove formation is suppressed, reducing the occurrence of cracks in the glass plate. Furthermore, when RSm2 is 150 μm or less, the contrast between the roughened region and the untreated region is increased, and the individual grooves are inconspicuous, resulting in a more uniform texture within the roughened region 22.

[0048] The above-mentioned arithmetic mean roughness Ra (Ra1, Ra2), maximum height Rz (Rz1, Rz2), and average length RSm (RSm2) of roughness curve elements are roughnesses determined in accordance with JIS B 0601 (2001). The arithmetic mean roughness Ra of the grooves is the arithmetic mean roughness Ra of the groove bottom, and may be, for example, the arithmetic mean roughness Ra measured along the center line of the groove.

[0049] The total area of the roughened region 22 in the identification mark 20 is 100 to 10,000 mm 2 Furthermore, when an imaginary circle is drawn to include the identification mark 20, the diameter of the imaginary circle may be 10 to 100 mm.

[0050] Furthermore, the glass plate 10 in the roughened area 22 of the identification mark 20 is transparent, and the visible light transmittance of the glass plate 10 measured by a measurement method in accordance with JIS R 3106:1998 may be preferably 70% or less, more preferably 60% or less. [Example]

[0051] In this example, a different method was used to form a roughened area on a glass plate. Specifically, a 3.5 mm thick, 100 mm long x 100 mm wide, untempered soda-lime glass plate manufactured by the floating method was prepared, and a 5 mm square roughened area was formed on one main surface.

[0052] (Example 1) A pulsed UV laser beam (wavelength 355 nm) was irradiated using a laser marking device (Keyence Corporation, MD-U1000C). The laser beam was scanned along one side of the square roughened area to be formed, with an output of 2.5 W, a frequency of 40 kHz, and a spot diameter of 25 μm, at a working distance of 189 mm and a scanning pitch of 80 μm, to form multiple grooves spaced apart in a direction perpendicular to the scanning direction. The laser beam was then irradiated along the contour of the periphery of the roughened area to form grooves around the periphery of the roughened area.

[0053] For five adjacent grooves, roughness curves were obtained along the groove extension direction (scanning direction), and the arithmetic mean roughness (Ra1) and maximum height (Rz1) were calculated. Furthermore, roughness curves along the orthogonal direction were obtained along five straight lines at a predetermined interval extending in a direction perpendicular to the groove extension direction (orthogonal direction), and the arithmetic mean roughness (Ra2) and maximum height (Rz2) were calculated. Furthermore, the length of the roughness curve element along the orthogonal direction (RSm2) was also calculated. The results are shown in Table 1.

[0054] (Example 2) As a comparative example, a pulsed green laser beam (wavelength 532 nm) was irradiated using a laser beam generator (Keyence Corporation, MD-T1000W). The irradiated beam had an output of 4 W, a frequency of 10 kHz, and a spot diameter of 20 μm. The beam was scanned at a working distance of 189 mm and a scanning pitch of 80 μm, forming multiple grooves spaced apart in a direction perpendicular to the scanning direction of the laser beam. The laser beam was then irradiated along the contour of the periphery of the roughened region, forming grooves around the periphery of the roughened region.

[0055] The arithmetic mean roughness (Ra1) and maximum height (Rz1) along the groove extension direction (scanning direction), as well as the arithmetic mean roughness (Ra2), maximum height (Rz2), and length of the roughness curve element (RSm2) along the perpendicular direction were determined in the same manner as in Example 1. The results are shown in Table 1.

[0056] (Example 3) In another comparative example, a sandblasting device was used to form a roughened area using a stencil plate having a shape corresponding to the shape of the roughened area. In this example, sandblasting was performed using abrasive sand having a diameter of 45 to 125 μm.

[0057] In Example 3, no grooves were formed, so roughness curves were obtained along five parallel straight lines spaced at intervals of approximately 80 μm along one side of the square roughened region, and the arithmetic mean roughness (Ra1) and maximum height (Rz1) were calculated. Furthermore, roughness curves were obtained along five parallel straight lines spaced at predetermined intervals along a direction perpendicular to the above straight lines, and the arithmetic mean roughness (Ra2), maximum height (Rz2), and length of the roughness curve element (RSm2) were calculated.

[0058] Table 1 shows the roughness values obtained in Examples 1 to 3. Each value is an average value.

[0059] [Table 1]

[0060] The roughened areas obtained in Examples 1 to 3 were observed with the naked eye. The roughened area formed by irradiation with UV laser light (Example 1) had a uniform texture, and the outline of the roughened area was clear. In contrast, the roughened area formed using a green laser with a longer wavelength than UV laser light (Example 2) and the roughened area formed using sandblasting (Example 3) gave the impression of non-uniform diffuse reflection within the area, and the outline of the roughened area was unclear.

[0061] Furthermore, the roughened regions were observed under magnification with a microscope. Figures 3(a) to 3(c) show partially enlarged photographs of the roughened regions obtained in Examples 1 to 3, respectively, taken using coaxial epi-illumination. As shown in Figure 3(a), the roughened region formed by irradiation with UV laser light (Example 1) had multiple regularly spaced grooves, and the groove contours were clearly defined. In contrast, as shown in Figure 3(b), the roughened region formed using a green laser with a longer wavelength than UV laser light (Example 2) had multiple grooves, but the groove contours were unclear. In addition, fine cracks were formed throughout the glass plate, resulting in irregular unevenness throughout the region. Furthermore, as shown in Figure 3(c), the roughened region formed by sandblasting had unevenly chipped areas on the surface.

[0062] This application claims priority from basic application No. 2020-095748, filed with the Japan Patent Office on June 1, 2020, the entire contents of which are incorporated herein by reference. [Explanation of symbols]

[0063] 1 UV laser light generator (marking device) 2 Laser light generating unit 5. Laser light 10 Glass Plate 20 Identification Mark 22 Roughened area 25a, 25b groove 100 Glass plate with identification mark

Claims

1. forming an identification mark on a main surface of the glass plate by irradiating the main surface with UV laser light; forming the identification mark includes forming a plurality of grooves spaced apart in a predetermined direction; the identification mark is depicted by a roughened area having a roughened surface, The roughened region has a microstructure in which elongated recesses and protrusions are repeated when viewed along a direction perpendicular to the extension direction of the grooves, a groove formed by irradiating the UV laser beam with a spot diameter of 10 to 40 μm, a width of the groove being 5 to 40 μm, a pitch of the groove being 3 μm or more and 1000 μm or less, and an average length RSm2 of a roughness curve element of the groove measured along the orthogonal direction being 50 to 150 μm.

2. The method of claim 1 , wherein the grooves have a predetermined width, and the pitch of the grooves exceeds the predetermined width.

3. The manufacturing method according to claim 2, wherein the predetermined width is 5 to 30 μm.

4. The method according to any one of claims 1 to 3, wherein the scanning speed of the UV laser light is 40 to 220 mm / sec.

5. The UV laser light is emitted in a pulsed oscillation mode with an energy density of 250 to 2500 kJ / m ２ The method according to claim 1 , wherein the irradiation is carried out at a temperature of 1000.degree.

6. The total area of the roughened region is 100 to 10,000 mm ２ The method according to any one of claims 1 to 5, wherein

7. A manufacturing method described in any one of claims 1 to 6, wherein the ratio (Rz2 / Rz1) of the second maximum height Rz2 of the groove measured along the perpendicular direction to the first maximum height Rz1 of the groove measured along the extension direction of the groove is 1 to 2.

8. A glass plate with an identification mark, a roughened area formed by roughening at least a part of the surface of the glass plate in at least a part of the identification mark; The roughened area has a plurality of grooves formed therein that are spaced apart from one another, The roughened region has a microstructure in which elongated recesses and protrusions are repeated when viewed along a direction perpendicular to the extension direction of the grooves, The width of the groove is 5 to 40 μm, the pitch of the groove is 3 μm or more and 1000 μm or less, and the average length RSm2 of the roughness curve element of the groove measured along the orthogonal direction is 50 to 150 μm, A glass plate with an identification mark, wherein the transparency of the roughened area is lower than the transparency of an untreated area other than the roughened area.

9. 9. The glass plate having an identification mark according to claim 8, wherein the width of the groove is 5 to 30 μm.

10. The glass plate with an identification mark according to claim 9 , wherein the pitch of the grooves exceeds the width.

11. The glass plate having an identification mark according to claim 8 , wherein the groove is linear.

12. A glass plate with an identification mark described in any one of claims 8 to 11, wherein the ratio (Rz2 / Rz1) of the second maximum height Rz2 of the groove measured along the perpendicular direction to the first maximum height Rz1 of the groove measured along the extension direction of the groove is 1 to 2.

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