JP2016185896A - Tempered glass, and marking method for tempered glass - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tempered glass having a mark formed thereon, and a marking method for a tempered glass, whereby it is possible to reduce the risk that the glass breaks.SOLUTION: A tempered glass has both surfaces and compressive stress layers formed in the vicinity of them, where a mark is formed at a position inside the compressive stress layer.SELECTED DRAWING: Figure 1

Description

  The present invention relates to tempered glass and a method for marking tempered glass.

  Tempered glass is a glass with compression stress layers formed on and near both surfaces of plate-like glass. For such tempered glass, marking that displays certification, manufacturer's logo, production lot, etc. is required. May be. In recent years, the necessity for ensuring traceability and process management has increased.

  Conventional methods for marking tempered glass (hereinafter also simply referred to as “glass”) include sand blasting and chemical etching. Sand blasting is a method in which a mask is placed on the surface of tempered glass, hard particles collide with a mark forming portion, and the surface of tempered glass is shaved and marked. Chemical etching is a method of marking by melting the surface of the tempered glass by placing a mask on the surface of the tempered glass and immersing it in a hydrogen fluoride solution. Recently, marking with a laser beam has been performed, and not only the surface of the tempered glass but also the internal marking has been tried.

  The marking on the inside is performed by condensing a laser beam having a wavelength that passes through the tempered glass inside the tempered glass. In that case, it is necessary to concentrate the laser beam energy spatially or temporally inside the tempered glass by condensing the laser beam into a fine beam diameter, shortening the pulse width of the laser oscillation. The merit of marking inside the tempered glass is that glass particles generated by the marking are not discharged to the outside. That is, it is possible to prevent the occurrence of problems such as contamination of the glass surface, manufacturing process equipment, and environment due to glass particles. Further, when marking is performed on the surface, the tempered glass is easily broken, but it is expected that the internal marking can prevent such breakage.

  Here, as a technique for forming discontinuous parts and altered parts inside the glass for internal marking, for example, a technique for marking the inside of the compressive stress layer with laser light (Patent Document 1), or irradiating laser light to tempered glass With the technique of forming a non-crosslinked oxygen hole center or a refractive index modulation part (Patent Document 2) or the like, there is a risk that the tempered glass is broken, and the glass plate is irradiated with laser light to form microcracks. In the technology (Patent Document 3) in which the glass is tempered by heating and quenching, there is a risk of breaking due to the growth of microcracks during or after heating and cooling.

  An object of this invention is to provide the tempered glass in which the mark was formed, and the marking method of tempered glass which can solve said problem, ie, can reduce the possibility that destruction will occur.

  In order to solve the above-described problem, the tempered glass of the present invention is a tempered glass in which a compressive stress layer is formed on both surfaces and in the vicinity thereof, as described in claim 1. A mark is formed at a location.

  In the tempered glass of the present invention, since a mark is formed at a position inside the compressive stress layer, crack generation on the surface of the tempered glass can be suppressed, and there is a risk of destruction even though the mark is formed. Can be reduced.

It is a model figure which shows an example of the laser processing apparatus used for marking. It is a model figure which shows an example of the marking method of the tempered glass of this invention. It is a photograph of the mark formed by an example of the marking method of the tempered glass of this invention. FIG. 3 is a model cross-sectional view showing the position of a mark formed by the marking method shown in FIG. 2. It is a model figure which shows the other example of the marking method of the tempered glass of this invention. FIG. 6 is a model cross-sectional view showing the position of a mark formed by the marking method shown in FIG. 5. It is a figure which shows the relationship between the distance (depth) from the tempered glass surface of a marking position, and the incidence rate of the crack of a surface. It is a model figure which shows the marking method of the tempered glass in a comparative example. It is a photograph of the mark formed with the marking method of the comparative example.

  The tempered glass used in the present invention is a tempered glass in which a compressive stress layer is integrally formed on both surfaces and in the vicinity thereof, and the compressive stress layer is formed by an ion exchange method. Alternatively, the air cooling strengthening method may be used.

  The size of the mark is usually preferably a size that can be visually recognized, but may be a size that can be detected using various optical devices.

  Such a mark is formed, for example, by condensing a laser beam having a wavelength that passes through the tempered glass to be processed as a fine spot on the order of several μm to several tens of μm at a location inside the tempered glass from the compressive stress layer. Is possible. Alternatively, it can also be formed by condensing a laser beam having a wavelength that transmits the tempered glass to be processed and a short pulse width such as femtosecond, picosecond, and nanosecond at a position inside the compression stress layer.

  Here, when the mark is formed by the laser beam, that is, when marking is performed, it is preferable that the mark is formed inside the compression glass and closer to the compression stress layer than the compression stress layer. That is, in the vicinity of the interface between the compressive stress layer in the tempered glass and the portion not affected by the tempering treatment inside thereof (hereinafter also referred to as “inner layer”), the energy processing threshold for forming a mark is lowered, Marking with an inexpensive laser oscillator with relatively low output is possible. Using such a low-power laser oscillator leads to preventing excessive energy from being applied to the tempered glass to be processed. For this reason, generation | occurrence | production of the crack in the surface (compressive stress layer) of tempered glass can be suppressed, and while processing yield improves, it becomes possible to further reduce the fear of destruction of tempered glass.

  In this way, the tempered glass is altered by the absorbed laser light, and a mark is formed. The alteration is an optical alteration such as a change in refractive index or transmittance. Alternatively, the mark may be formed by forming a discontinuous portion in the glass by partially heating the glass with laser light. As a discontinuous portion, a mark can be formed by generating a plurality of micro cracks, that is, micro cracks. Formation of such a mark by microcracks is easy and visibility is good, which is preferable.

  In the present invention, the position where such a mark is formed needs to be inside the tempered glass rather than the compressive stress layer. When a mark is formed in the compressive stress layer, cracks tend to develop on the glass surface, and the risk of breaking the tempered glass increases.

  Here, the thickness of the compressive stress layer is represented by DOL (depth of layer) as an index representing the strengthening characteristics of the tempered glass. In the present invention, it is necessary to form a mark at a position deeper than the compressive stress layer, that is, at a position deeper than the thickness corresponding to DOL from both surfaces of the tempered glass.

  As mentioned above, although this invention was demonstrated and mentioned with preferable embodiment, the marking method of the tempered glass of this invention and tempered glass is not limited to the structure of the said embodiment.

  A person skilled in the art can appropriately modify the tempered glass of the present invention and the marking method of the tempered glass according to known knowledge. Of course, such modifications are included in the scope of the present invention as long as they have the configuration of the tempered glass and the marking method of the tempered glass.

The present invention will be specifically described below with reference to examples.
<Example 1>
Marking the inside of tempered glass with laser light was performed for chemically tempered glass by ion exchange. The used chemically strengthened glass has a DOL of 50 μm and an overall thickness of 500 μm. The laser beam used is a third harmonic wave (wavelength: 355 nm) of the YVO ₄ laser and has a pulse width of 15 ns (nanoseconds). The marking conditions are an average output of 0.7 W, a repetition frequency of 30 kHz, and a beam diameter of 10 μm.

  FIG. 1 schematically shows a laser processing apparatus used for marking. The control unit 23 is connected to the laser device 22 and the stage 21 holding the tempered glass 10 to be marked by a signal line 24a and a signal line 24b, respectively.

  Laser light emitted from a laser oscillator (not shown) inside the laser device 22 is scanned by a galvanometer mirror and collected by an fθ lens. The condensed laser beam L is irradiated to the tempered glass 10. A control signal from the control unit 23 controls the ON / OFF of the laser beam L of the laser device 22 and the alignment of the stage 21 to form a mark having a predetermined shape on the tempered glass 10.

  As shown in FIG. 2 as a model, the laser light L is in the inner layer 10b of the tempered glass 10, that is, on the inner side of the compressive stress layer 10a and on the incident side (the reference numeral 10a1 is attached to indicate the incident surface). The positional relationship between the fθ lens 2 and the tempered glass 10 is set so that the light is condensed at a location in the vicinity of the compressive stress layer 10a, and a data matrix of a two-dimensional code representing an 8-digit number “12345678” is used as a mark. Formed.

  FIG. 2 shows a photograph of the mark. A portion of the mark that appears white is formed by a collection of a plurality of microcracks of about 5 μm. Here, as shown in the model cross-sectional view of FIG. 3, the position of the mark 3 (depth from the incident surface 10a1 of the tempered glass 10) is within the inner layer 10b of the tempered glass 10 and the compressive stress on the emission side. It is formed so as to be in the vicinity of the layer 10a. Thus, by setting the condensing position in the inner layer 10b, the microcracks exist only in the inner layer 10b, and no cracks occurred on the incident surface 10a1. This mark 3 could be read using a commercially available two-dimensional code reader.

<Example 2>
Marking the inside of the tempered glass with a laser beam was performed on the chemically tempered glass by the ion exchange method. The tempered glass used here has a DOL of 50 μm and an overall thickness of 500 μm.

  The laser beam used is a fundamental wave (wavelength: 1064 nm) of a YAG laser and has a pulse width of 100 ps (picoseconds). The marking conditions are an average output of 3 W, a repetition frequency of 100 kHz, and a beam diameter of 30 μm.

  As shown in the model cross-sectional view in FIG. 5, marking was performed by setting the laser beam so as to be condensed in the inner layer 10 b of the tempered glass 10 and in the vicinity of the compressive stress layer 10 a on the emission side.

A model cross-sectional view of the tempered glass 10 on which the mark is formed is shown in FIG.
The mark 3 is a data matrix of a two-dimensional code as in the first embodiment, and is formed by microcracks. Even in the case where marking is performed on a portion in the vicinity of the compressive stress layer 10a on the inner side of the compressive stress layer 10a of the tempered glass 10 and the outgoing side (the reference numeral 10a2 is attached to indicate the outgoing surface) as in this example, It is necessary that the mark 3 exists inside the tempered glass 10a from the compressive stress layer 10a. In this way, no cracks were generated on the surface of the tempered glass 10 by setting the light condensing position in the inner layer. This mark 3 could be read with a commercially available two-dimensional code reader.

<Example 3>
For the tempered glass strengthened by the air-cooling tempering method, the inside of the tempered glass was marked with laser light. This tempered glass has a DOL of 1 mm and an overall thickness of 5 mm. The laser beam used is a fundamental wave (wavelength: 1064 nm) of a YVO ₄ laser and has a pulse width of 10 ns (nanoseconds). The marking conditions are an average output of 2 W, a repetition frequency of 10 kHz, and a beam diameter of 20 μm.

  In the same manner as in Example 1, the data matrix of the two-dimensional code was marked so that the laser light was condensed in the inner layer of the tempered glass and in the vicinity of the compressive stress layer on the incident side. The formed mark was composed of a collection of about 10 μm microcracks. Thus, by setting the condensing position in the inner layer, these micro cracks were formed only in the inner layer inside the compressive stress layer of the tempered glass, and no crack was generated on the surface of the glass. This mark could be read with a commercially available two-dimensional code reader.

<Examination on marking position>
The relationship between the distance from the tempered glass surface at the marking position and the frequency of surface cracks was investigated. That is, it is the same as in Example 1 except that chemically tempered glass (DOL: 50 μm, overall thickness: 500 μm) by ion exchange method is targeted, and the marking distance from the glass surface is changed in the range of 0 μm to 200 μm. A sample in which a mark was formed was produced, and the frequency of occurrence of cracks on the surface at that time was evaluated. The results are shown in FIG.

  According to FIG. 7, when the mark is formed on the surface of the tempered glass, the frequency of occurrence of cracks on the surface is almost 100%, and when the mark is formed inside the compression stress layer having a thickness of 50 μm from the surface of the tempered glass, It can be seen that the occurrence frequency of cracks is 30% or more. It is also understood that cracking on the surface of the tempered glass can be prevented when marking is performed on the inner side of the compressive stress layer of the tempered glass. In addition, the same result was obtained even if it used the tempered glass tempered by the air-cooling tempering method instead of the tempered glass by the ion tempering method.

<Comparative example>
As in Example 1, except that the laser beam is focused in the compressive stress layer 10a on the incident side of the tempered glass (position of 25 μm from the glass surface), as schematically shown in FIG. Marking was performed. As a result of marking, cracks occurred on the surface of the tempered glass, and reading was impossible.

  For this reason, in order to reduce cracks on the glass surface, the average output was reduced from 0.7 W to 0.4 W, and marking was attempted again. As a result, since the average output was reduced, the mark was thin and the contrast was low, but cracks were still generated on the tempered glass surface, and reading was impossible. A photograph of the mark obtained at this time is shown in FIG.

L laser beam 2 fθ lens 3 mark 10 tempered glass 10a compressive stress layer 10a1 entrance surface 10a2 exit surface 10b inner layer 21 stage 22 laser device 23 controller

JP 2004-323252 A JP 2004-2056 A JP 2005-324997 A

Claims (7)

  A tempered glass in which a compressive stress layer is formed on both surfaces and in the vicinity thereof, wherein a mark is formed at a location inside the compressive stress layer.   The tempered glass according to claim 1, wherein the mark is formed in the vicinity of the compressive stress layer.   The tempered glass according to claim 1 or 2, wherein the mark is formed by partially modifying the tempered glass or by partially discontinuing the tempered glass. Glass.   The tempered glass according to claim 3, wherein the mark is formed by a microcrack that makes the tempered glass partially discontinuous.   The tempered glass according to any one of claims 1 to 4, wherein the mark is formed by condensing a laser beam.   A method of marking tempered glass in which a compressive stress layer is formed on both surfaces and in the vicinity thereof, wherein the mark is formed by condensing a laser beam at a location inside the compressive stress layer. Marking method for tempered glass.   The tempered glass marking method according to claim 6, wherein the mark is formed in the vicinity of the compressive stress layer.

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