Glass article, method for manufacturing the same, and use thereof

Abstract

A glass article is presented that is composed of an aluminosilicate glass characterized by particularly good surface and internal quality. The glass is produced using alternative fining agents and has very low amounts of precious metal particles.

Description

Technical Field

[0001] The present invention relates to a glass article, a method for manufacturing the same, and use thereof. The glass article is suitable for use as a display glass for, for example, mobile phones and tablet computers.

[0002] Prior Art In particular, mobile terminal device manufacturers such as smartphone and tablet computer manufacturers are troubled by the progress of market saturation. It is difficult to encourage consumers to purchase new devices with attractive features. On the one hand, there is a dilemma of providing a more vivid and larger display to display multimedia content as impressively as possible on a wearable screen, while on the other hand, keeping the size of the device within a reasonable range. In particular, research on foldable and curved displays is progressing. Smartphones with curved screens have already achieved success in the market. Innovative materials for such displays are highly demanded in order to meet customer requirements.

[0003] Glass is selected as a display material because of its excellent chemical resistance, durability, and transparency. In order to be able to bend the glass, it is necessary to be able to use it with a small thickness. There are already various processes for manufacturing very thin glass. Very thin glass can be manufactured by the draw process. The draw process includes a down-draw process (also called a slot down-draw process) and an overflow fusion process (also called an overflow down-draw process). What these processes have in common is that a platinum component is used in the corresponding manufacturing apparatus.

[0004] In the production of thin glass, it has been found that platinum particles are released from the precious metal parts of the production equipment and are again found on or in the thin glass articles. Since these platinum particles are small in thick glass articles, they are not as critical as in the case of thin glass articles. For example, since the surface may bulge around defects, in a 50 μm thick glass, a single platinum particle with a size of only 5 μm in diameter can be a very serious defect.

[0005] Since aluminosilicate glass contains a large amount of Al2O3, it melts at a relatively high temperature. Aluminosilicate glass does not reach the normal fining viscosity (200 - 500 dPa·s) unless at a very high temperature, so fining is more difficult than for many other glasses. In particular, it has been found that it is difficult to obtain a satisfactory fining effect without using harmful fining agents such as arsenic oxide and antimony oxide. Many alternative fining agents release fining gases at too low a temperature. At this time, since the viscosity of the glass is still too high, the formed bubbles do not rise fast enough or do not rise at all.

[0006] Since alkali metal oxides lower the melting temperature and fining temperature of the glass, the desired fining viscosity is already achieved at a lower temperature. However, glasses with a high proportion of alkali metal oxides show high corrosivity to tank blocks and precious metal parts. In particular, precious metals are present in many parts during glass production, for example, in the form of tubes for transporting the glass melt from the melting tank to the homogenization and forming system, and are strongly attacked. As a result, the life of the equipment is shortened, leading to high costs.

[0007] WO 2009 / 108285 teaches a composite fining agent for aluminosilicate glass based on the use of polyvalent metal oxides and water. In this case, glass with a bubble density of at most 1 per 1 cm 3 of glass can be obtained. Tin oxide and cerium oxide are used as polyvalent metal oxides.

[0008] Devices for manufacturing thin and flat glass usually contain precious metal components such as platinum tubes. For example, International Publication No. WO 2006 / 115997 describes a glass manufacturing device having a precious metal, especially platinum. The "hydrogen permeation blister" effect, i.e., the generation of bubbles inside the platinum component for this material to permeate hydrogen, is explained. In particular, tin oxide is recommended for use there because it absorbs the remaining bubbles even during the cooling of the melt. To promote hydrogen permeation blisters, it is desirable to use a very small amount of iodine, bromine or chlorine and control the hydrogen partial pressure outside the device.

[0009] It is desirable to provide aluminosilicate glass of excellent quality without requiring a complex combination of fining agents or high equipment costs. Also, it is desirable that the glass does not contain arsenic or antimony and does not attack the materials of the device as much as possible.

[0010] Detailed Description of the Invention In a first aspect, the present invention relates to a glass article composed of aluminosilicate glass having at least one halogen having a fining action in the range of 500 to 8000 ppm and an Sn content of 500 ppm or less, wherein the glass has As of 100 ppm or less and Sb of 100 ppm or less.

[0011] In a second aspect, the present invention relates to a glass article composed of aluminosilicate glass, wherein the number of platinum particles having a diameter exceeding 5 μm in the glass article is 5 or less per 1 kg of glass, and the aluminosilicate glass has As of 100 ppm or less and Sb of 100 ppm or less.

[0012] In a third aspect, the present invention relates to a glass article composed of aluminosilicate glass, wherein the aluminosilicate glass has As of 100 ppm or less, Sb of 100 ppm or less, and Sn of 500 ppm or less or 100 ppm or less, and quotient A is in the range of 1.5 to 8.5.

Number

[0013] In the formula, m Al2O3 is the weight fraction in units of weight % of Al2O3 in the aluminosilicate glass, and m R2O is the total of the weight fractions in units of weight % of the alkali metal oxides Na2O, K2O, and Li2O, and m RO is the total of the weight fractions in units of weight % of the alkaline earth metal oxides MgO, CaO, BaO, and SrO, and m Cl is the weight fraction in units of weight % of chlorine, and m I is the weight fraction in units of weight % of iodine, and m Br is the weight fraction in units of weight % of bromine.

[0014] In a fourth aspect, the present invention relates to a glass article composed of aluminosilicate glass, the aluminosilicate glass having As of 100 ppm or less, Sb of 100 ppm or less, and Sn of 500 ppm or less, preferably 100 ppm or less, and the overall thickness unevenness of the glass article being 5 μm or less.

[0015] Aluminosilicate glass has at least one clarifying halogen selected particularly from chlorine, bromine, and iodine. Fluorine is not a clarifying halogen because it already volatilizes at too low a temperature. However, the glass can contain fluorine. A preferred halogen for clarification is chlorine. The content of the clarifying halogen may be at least 100 ppm, at least 300 ppm, or at least 500 ppm. In one embodiment, the halogen content is at most 8000 ppm, at most 6500 ppm, at most 5000 ppm, at most 3000 ppm, at most 2500 ppm, or at most 1000 ppm. The clarifying halogen acts as a fining agent to remove bubbles during the manufacture of glass articles. The clarifying halogen can be added in various forms. In one embodiment, the halogen is added to the batch as a salt with an alkali metal cation or an alkaline earth metal cation. In one embodiment, the halogen is used as a salt, and the cation of the salt corresponds to the cation present as an oxide in the aluminosilicate glass.

[0016] It is surprising that very good quality can be obtained by using a halogen as a fining agent for aluminosilicate glass. Since the halogen has a relatively low boiling point, it releases clarifying gas relatively early in the melting process. Also, unlike polyvalent metal oxides, the clarifying halogen cannot absorb oxygen when the melt is cooled. Therefore, it has been the conventional common sense that the halogen cannot give satisfactory results unless it is used in combination with other fining agents, particularly polyvalent metal oxides, especially SnO2. The inventors have found that very good fining results can be obtained without using tin oxide, arsenic oxide, or antimony oxide. Preferably, the aluminosilicate glass does not contain such a fining agent.

[0017] In one embodiment, in addition to the clarifying halogen, one or more additional clarifying agents may be used. In particular, cerium oxide and / or iron oxide are applicable. Thus, in one embodiment, the glass contains CeO2 and / or Fe2O3. CeO2 may be included, for example, in a proportion in the range of up to 2000 ppm, or up to 1000 ppm. This amount alone is not sufficient for clarification. However, in combination with the clarifying halogen, very good results can be obtained. The proportion of CeO2 can be at least 100 ppm. Fe2O3 can be used, for example, in a proportion in the range of up to 300 ppm. This amount alone is not sufficient for clarification. However, in combination with the clarifying halogen, very good results can be obtained. The proportion of Fe2O3 can be at least 100 ppm.

[0018] The aluminosilicate glass of the glass article can have an Sn content of 500 ppm or less, particularly 300 ppm or less, 100 ppm or less, 50 ppm or less, or 10 ppm or less. In one embodiment, the glass has an arsenic content of 100 ppm or less, particularly 50 ppm or less, or 10 ppm or less. Preferably, the glass has an antimony content of 100 ppm or less, 50 ppm or less, or 10 ppm or less. Arsenic and antimony are toxic and have a high environmental impact. Therefore, these should be avoided as components of glass articles and are no longer desirable or acceptable in many applications. To date, much effort has been spent on replacing fining agents such as arsenic and antimony, which are excellent in fining action. This has been mainly achieved by using tin oxide as a fining agent. When manufacturing relatively thick glass articles, using tin oxide as a fining agent has substantially no problems. However, it has been found that when using tin oxide, platinum particles elute from platinum parts, especially when the glass is flowed through a platinum tube. These platinum particles are again found on or in the glass article. Particularly in the case of thin glass articles, since solid particles do not deform together during molding and a thickness much larger than the particles themselves occurs, even very small platinum particles become noticeable. The present invention has succeeded in significantly reducing the amount of platinum particles on or in the glass article. In one embodiment, the platinum particles having a diameter of more than 5 μm, particularly more than 10 μm, in the glass article are 5 or less per 1 kg of glass. In particular, this corresponds to particles having a diameter of 5 to 100 μm. In one embodiment, such platinum particles in the glass article are 3 or less, 1 or less, or 0 per 1 kg of glass. If there is even one platinum particle with a diameter of more than 5 μm, it may cause a major drawback in the manufacture of thin glass articles. The diameter of platinum particles of this size can be measured with a microscope, and the numerical values indicated in micrometers in this specification correspond to the maximum diameter of each particle. Preferably, the platinum particles in the glass article are 10 or less, particularly 8 or less, 6 or less, 4 or less, 3 or less, 2 or less, 1 or less, or even 0.5 or less per 1 square meter of the glass article.

[0019] It has been found to be advantageous when the quotient A is in the range of 1.5 to 8.5, where

Number

[0020] In the formula, m Al2O3 is the weight fraction in units of weight % of Al2O3 in the aluminosilicate glass, and m R2O is the total of the weight fractions in units of weight % of the alkali metal oxides Na2O, K2O, and Li2O, and m RO is the total of the weight fractions in units of weight % of the alkaline earth metal oxides MgO, CaO, BaO, and SrO, and m Cl is the weight fraction in units of weight % of chlorine, and m I is the weight fraction in units of weight % of iodine, and m Br is the weight fraction in units of weight % of bromine. Particularly preferably, the quotient A is at least 1.5, or at least 2.0, especially at least 2.5. Preferably, the quotient A is at most 8.5, at most 7, or at most 5.

[0021] The glass article of the present invention has a very low bubble density. In particular, the number of bubbles with a length exceeding 20 μm in the glass article is 100 or less per 1 kg of glass, particularly 50 or less per 1 kg of glass, 20 or less per 1 kg of glass, or 10 or less per 1 kg of glass. The length of the bubble is its longest diameter.

[0022] In one embodiment, the glass article has a thickness of 500 μm or less, 350 μm or less, 250 μm or less, 200 μm or less, or 100 μm or less. Preferably, the thickness of the glass article is at least 5 μm, at least 10 μm, or at least 15 μm. Of course, since the relationships found here also hold in principle for thicker glass, in one embodiment, the glass article has a thickness of 0.1 to 2 mm, particularly 0.2 to 1 mm.

[0023] Preferably, the glass article is a thin glass sheet, a glass wafer or a glass ribbon. Preferably, the glass article is a planar glass body having two substantially parallel planes with a much larger area than all other surfaces. The glass article may be in the form of a glass ribbon or may be in a state of being wound around a roll. The shape of the glass article may be any shape such as a rectangular parallelepiped or a circle. The length of the wound glass ribbon may be 10 to 1000 m.

[0024] The glass article can preferably be manufactured by a draw process, particularly a down-draw process, an overflow fusion process, or a redraw process. By these draw processes, an excellent surface quality characterized by particularly low roughness can be obtained. Such a surface is also called "fire polished". In one embodiment, the glass article has at least one fire-polished surface, and in particular at least two of the largest surfaces of the article are fire-polished. In particular, the article has a surface quality with a roughness R a of at most 10 nm, at most 1 nm, or at most 0.5 nm. The roughness R a is measured using an atomic force microscope (AFM).

[0025] Since the glass article has good quality regarding platinum particles and bubbles, it is preferably particularly uniform with respect to the thickness of the article. In particular, the article can have a total thickness variation (TTV) of 5 μm or less, particularly 3 μm or less, 2 μm or less, or even 1 μm or less. The total thickness variation is the difference between the maximum thickness and the minimum thickness of the glass article and can be determined in accordance with SEMI 1530 GBIR. Preferably, the indicated total thickness variation applies to a glass article area of at least 50 cm 2 at least 100 cm 2 at least 250 cm 2 at least 800 cm 2 or at least 1500 cm 2 The indicated total thickness variation is 10000 cm 2up to, or 5000 cm 2 It is applicable to an area up to. In one embodiment, the shown TTV is applied to the entire glass article. In a thin glass article containing a large amount of platinum particles, this overall thickness non-uniformity is not achieved because the particles in the glass cause bulges, i.e., portions where the thickness increases.

[0026] The glass article can have an area of at least 10 cm 2 at least 50 cm 2 at least 100 cm 2 at least 200 cm 2 or at least 400 cm 2 In one embodiment, the glass article can have an area of up to 25 m 2 up to 15 m 2 up to 100000 cm 2 up to 60000 cm 2 up to 10000 cm 2 or up to 2000 cm 2 The area of the glass article is the product of its length and its width.

[0027] In one embodiment, the aluminosilicate glass has 100 ppm or less of fluorine, or does not contain fluorine. Fluorine may evaporate during manufacturing, thereby making the glass inhomogeneous. However, in one embodiment, the aluminosilicate glass has fluorine because fluorine acts as a flux during melting. In one embodiment, the glass contains fluorine at a rate of at least 0.05 wt%. However, in order to avoid the aforementioned drawbacks, its content can be limited to a maximum of 0.5 wt%.

[0028] The aluminosilicate glass may contain alkali metal oxides. In particular, the aluminosilicate glass can have a total of more than 0.5 wt%, more than 2 wt%, more than 5 wt%, or more than 10 wt% of lithium oxide, sodium oxide and / or potassium oxide (alkali metal oxides). In one embodiment, the aluminosilicate glass has 100 ppm or less of lithium or does not contain lithium. Lithium may impair the chemical resistance of the glass article and may attack the material of the crucible.

[0029] In one embodiment, the fining temperature T in °C when the aluminosilicate glass exhibits its fining viscosity L and the temperature T in °C of the boiling point of a halogen compound such as NaCl used for fining S(ハロゲン) The ratio of is at most 1.2 or at most 1.15. Preferably, this ratio T L / T S(ハロゲン) is greater than 1.00 or greater than 1.05. It has been found that good fining results can be obtained by maintaining this ratio. This is surprising since the doctrine was that it was desirable for the fining temperature and the boiling point of the fining agent to be approximately the same. Therefore, the halogen was considered to have little fining effect. The fining temperature herein is the temperature at which the viscosity of the glass becomes 300 dPa·s. This does not mean that the glass has been fined at this temperature. The temperature corresponding to a viscosity of 300 dPa·s represents the temperature at which the glass has a viscosity suitable for fining. The glass of the present invention can be fined in a viscosity range of 200 to 500 dPa·s. The viscosity of the glass can be measured using a rotational viscometer conforming to, for example, DIN ISO 7884-2:1998-2. The temperature dependence of the viscosity is determined using a VFT curve (Vogel-Fulcher-Tammann equation).

[0030] In one embodiment, the aluminosilicate glass has a fining temperature of at least 1500 °C, particularly at least 1550 °C. The fining temperature of the aluminosilicate glass can be at most 1700 °C or at most 1650 °C.

[0031] In one embodiment, the aluminosilicate glass has SiO2 in a proportion of at least 40 wt% and / or at most 75 wt%. SiO2 contributes to the desired viscosity characteristics and hydrolysis resistance. The proportion of Al2O3 can preferably be at least 10 wt% and / or at most 30 wt%. By containing a certain amount of Al2O3, the desired chemical strengthening can be obtained. To ensure sufficient chemical strengthening, the aluminosilicate glass preferably contains at least 9 wt% of Na2O. The content of Na2O can be limited to at most 18 wt%, or at most 16 wt%.

[0032] In one embodiment, the glass does not contain B2O3 or contains only a small amount of B2O3. Certainly, B2O3 has a good effect on hydrolysis resistance. However, this has an adverse effect on chemical strengthening. Therefore, its content is preferably limited to at most 20 wt%, at most 10 wt%, at most 5 wt%, or at most 2 wt%.

[0033] Preferred alkali metal oxide-containing aluminosilicate glass has the following components.

[0034]

Table 1

[0035] In one embodiment, the aluminosilicate glass has a β-OH content represented by an absorption coefficient a of at most 0.32 mm -1 The β-OH content represented by the absorption coefficient a serves as an index of the water content of the glass. The water content of the aluminosilicate glass is relatively low compared to the prior art. The absorption coefficient a is determined as follows by infrared spectroscopy. First, an IR spectrum is recorded, and the minimum value of the transmittance in the wavelength range of 2.7 to 3.3 μm is obtained. The absorption coefficient at the minimum wavelength is calculated as follows.

[0036]

Equation

[0037] In one embodiment, the aluminosilicate glass has NH4 of 0.0001 wt% or less + by weight.

[0038] In one embodiment, the aluminosilicate glass has a cooling state corresponding to the cooling of the glass through a temperature range from 50 °C higher than Tg to 100 °C lower than Tg at a cooling rate of at least 300 °C / min during production. In particular, the cooling state of the glass corresponds to a cooling rate of at least 1000 °C / min through this temperature range. The cooling rate can be further up to 6000 °C / min. The aluminosilicate glass can be quenched so as to have a relatively high fictive temperature at the indicated cooling rate near Tg. A high fictive temperature is associated with a refractive index lower than that after slightly cooling the same glass composition. When the fictive temperature is high, relatively high strengthening is possible and the density can be slightly reduced. The aluminosilicate glass can have a density of 2.5 g / cm 3 or less. In one embodiment, the glass has a refractive index n D of 1.48 to 1.55. According to the present invention, preferably, the aluminosilicate glass having a refractive index n D of at most 1.55 and a thickness of 500 μm or less, which can be produced particularly by the method according to the present invention. The refractive index of the aluminosilicate glass can be at least 0.0001 smaller than the refractive index after slight cooling. Particularly preferably, the refractive index of the glass is further at least 0.0004 smaller, and particularly preferably at least 0.0008 smaller than the refractive index after slight cooling. In an alternative embodiment, the refractive index is further at least 0.001 or 0.002 smaller than the refractive index after slight cooling.

[0039] The refractive index after slight cooling is obtained by first determining the refractive index of the aluminosilicate glass, heating the aluminosilicate glass after production to a temperature corresponding to T G +20 K, and then cooling it to a temperature of 20 °C at a cooling rate of 2 K / h. Then, the refractive index is measured again (= refractive index after slight cooling), and the difference from the refractive index before this recooling is determined. In a preferred embodiment, the transformation temperature T G of the aluminosilicate glass is 580 to 650 °C.

[0040] In one embodiment, the glass article or aluminosilicate glass is chemically curable, and in particular, at least 14 μm 2 / h, in particular at least 18 μm 2 / h, or at least 20 μm 2 / h in terms of diffusivity. The diffusivity is chemically curable. The diffusivity is limited to a maximum of 60 μm 2 / h, a maximum of 45 μm 2 / h, or a maximum of 30 μm 2 / h in some cases. The diffusivity D is an indicator showing the sensitivity of the glass article to chemical strengthening. This can be calculated from the depth of the compressive stress layer (DoL, depth of ion exchanged layer) and the strengthening time t. Here,

Equation

[0041] In this specification, the diffusivity when strengthened at 450 °C for 1 hour using KNO3 is shown. The diffusivity does not mean that the article must be strengthened, but represents the sensitivity of the article to strengthening. Glass that has been rapidly cooled has a high sensitivity to chemical strengthening and has a higher diffusivity than glass that has been slowly cooled.

[0042] In one embodiment, the glass article is strengthened. The compressive stress on at least one surface of the glass article, particularly on one or both of the largest surfaces of the glass article, is at least 100 MPa, preferably at least 200 MPa, particularly at least 300 MPa, or at least 400 MPa. In one embodiment, the compressive stress on at least one surface of the glass article, particularly on one or both of the largest surfaces of the glass article, is at most 2000 MPa, at most 1600 MPa, at most 1400 MPa, at most 1000 MPa, particularly at most 800 MPa, or at most 750 MPa. The compressive stress can preferably be at least 100 MPa, at least 300 MPa, or at least 500 MPa. The desired compressive stress is introduced by those skilled in the art in a manner known per se by replacing small ions with large ions on the surface of the glass. Preferably, sodium is exchanged with potassium, and particularly KNO3 is used. The depth of layer (DoL) of the compressive stress layer can be at most 1 / 3 of the thickness of the glass, particularly at most 25%, at most 20%, or at most 15%. The DoL can be at least 1% or at least 10% of the thickness of the glass. The article can be strengthened on one side or on both sides.

[0043] According to the present invention, the glass article according to the present invention is also used in mobile or wearable terminal devices, particularly mobile phones, tablet computers or smart watches.

[0044] The present invention also relates to a method for manufacturing a glass article, particularly the glass article as described above, - providing a batch for aluminosilicate glass having a Sn content of 500 ppm or less, particularly the batch for aluminosilicate glass according to the composition described herein; - melting the batch to obtain a melt; - clarifying the melt by utilizing the clarifying action of at least one halogen; - forming the glass article, particularly by a drawing process and relates to a method comprising.

[0045] In one embodiment, a batch for aluminosilicate glass having a Sn content of 100 ppm or less, particularly aluminosilicate glass according to the composition described herein, is provided.

[0046] The draw process may be selected from vertical draw processes such as the down-draw process, the up-draw process, the redraw process, and the overflow fusion process, and horizontal draw processes such as the float process.

[0047] The clarifying halogen can be used in the form of a halogen compound, particularly a halide compound. Suitable halide compounds are salts of chlorine anions, bromine anions and / or iodine anions with alkali metal cations or alkaline earth metal cations in particular. Preferred examples are NaCl, NaBr, NaI, KCl, KBr, KI, MgCl2, MgI2, MgBr2, CaCl2, CaI2, CaBr2, and combinations thereof. Other preferred examples are BaCl2, BaBr2, BaI2, SrCl2, SrBr2, SrI2, and combinations thereof. The amount of halogen used may be at least 100 ppm, at least 300 ppm, or at least 500 ppm, where the numerical value of the amount means the weight fraction of the halogen relative to the batch. In one embodiment, the weight fraction of the clarifying halogen used relative to the batch is at most 10,000 ppm, at most 8,000 ppm, at most 6,000 ppm, at most 5,000 ppm, or at most 3,000 ppm. The clarifying halogen acts as a fining agent to remove bubbles during the manufacture of glass articles. The halogen can be added in various forms. In one embodiment, the halogen is added to the batch in the form of a halide compound, for example as a salt with an alkali metal cation or an alkaline earth metal cation. In one embodiment, the halogen is used as a salt, and the cation of the salt corresponds to the cation present as an oxide in the aluminosilicate glass. According to the present invention, fluorine compounds are not included in the halogen compounds used for clarification because their boiling points are too low to obtain sufficient clarification. Nevertheless, the batch may contain fluorine or fluoride.

[0048] In one embodiment, the fining treatment is carried out at a temperature at which the melt exhibits a viscosity in the range of 200 to 500 dPa·s, particularly about 300 dPa·s. Preferably, the fining temperature in °C is in a ratio of at least 0.8 and at most 1.4, preferably at least >1 and at most 1.2, or at most 1.15, with respect to the boiling point in °C of the halogen compound used. The melting and / or fining treatment of the glass is preferably carried out at a temperature of at least 1400 °C, preferably at least 1500 °C. In particular, this temperature is at most 1700 °C, preferably at most 1650 °C.

[0049] The melt can, in the process, come into contact at least temporarily with platinum parts, such as platinum tubes or platinum stirrers. In this way, the advantages of the present invention regarding the very low platinum loss can be optimally utilized. Platinum has great advantages in glass production. Platinum has very low corrosiveness, is resistant to high temperatures, is mechanically stable, and exhibits conductivity, so it can also be directly heated. According to the present invention, it is possible to advantageously use platinum even for highly corrosive glass.

[0050] The forming of the glass article particularly includes making the melt or the glass into a thin glass article by a drawing process. In this case, the glass can be drawn to a very low thickness of about 100 μm or less. When platinum particles are present in the glass, these platinum particles appear on the surface during the drawing process and the glass quality is impaired.

[0051] In one embodiment, the glass is an aluminosilicate glass having the following components:

Table 2

[0052] In one embodiment, the glass is an aluminosilicate glass having the following components:

Table 3

[0053] In one embodiment, the glass is an aluminosilicate glass having the following components: [Table 4]

[0054] In one embodiment, the glass is an aluminosilicate glass having the following components: [Table 5]

[0055] If necessary, coloring oxides such as Nd2O3, Fe2O3, CoO, NiO, V2O5, MnO2, TiO2, CuO, CeO2, Cr2O3, or combinations thereof can be added to the glass. The glass preferably does not contain Sn, Sb, and / or As.

[0056] In one embodiment, the glass is an aluminosilicate glass containing the following components: 50 wt% SiO2, 12 wt% Al2O3, 14 wt% B2O3, and 24 wt% BaO. In one embodiment, the glass is an aluminosilicate glass containing the following components: 61 wt% SiO2, 16 wt% Al2O3, 8 wt% B2O3, 3 wt% MgO, 8 wt% CaO, and 4 wt% BaO. In one embodiment, the glass is an aluminosilicate glass containing the following components: 61 wt% SiO2, 17 wt% Al2O3, 11 wt% B2O3, 3 wt% MgO, 5 wt% CaO, and 3 wt% BaO.

[0057] The glass article may be a thin glass ribbon or a glass film. The glass article can have a thickness of 500 μm or less, 350 μm or less, preferably 250 μm or less, preferably 100 μm or less, and particularly preferably 50 μm or less. In one embodiment, the thickness is at least 3 μm, preferably at least 10 μm, and particularly preferably at least 15 μm. Preferred thicknesses are 5 μm, 10 μm, 15 μm, 25 μm, 30 μm, 35 μm, 50 μm, 55 μm, 70 μm, 80 μm, 100 μm, 130 μm, 145 μm, 160 μm, 175 μm, 190 μm, 210 μm, 280 μm, or 330 μm.

[0058] When the concentration unit ppm is used in this specification, if not otherwise apparent, it is expressed as a weight fraction.

[0059] In this specification, regarding chemical elements (e.g., Sn, As, Sb), when it is described that this component is not contained or the content of this component is limited to a certain ratio, this description is for any chemical form. For example, the description that the glass has a Sn content of 100 ppm or less means that the total weight fraction of the existing Sn species (e.g., Sn in SnO 2+ and Sn in SnO2 4+ ) does not exceed a value of 100 ppm.

[0060] In this specification, when it is said that the glass does not contain or does not include a certain component, this means that this component may exist as an impurity in some cases. That is, this means that this component is not added in a major amount. According to the present invention, a non-major amount is an amount of 100 ppm or less, preferably 50 ppm or less, and most preferably 10 ppm or less.

Brief Description of the Drawings

[0061] [Fig. 1] It is a phase diagram of platinum and tin. [Fig. 2] It is an SEM image of a sample of a noble metal tube in long-term contact with a Sn-containing glass melt. [Fig. 3] SEM image of a sample of a noble metal tube that has been in contact with an Sn-containing glass melt for a long time. [Fig. 4] SEM image of a sample of a noble metal tube that has been in contact with an Sn-containing glass melt for a long time. [Fig. 5] SEM image of a sample of a noble metal tube that has been in contact with an Sn-containing glass melt for a long time. [Fig. 6] SEM image of a sample of a noble metal tube that has been in contact with an Sn-containing glass melt for a long time. [Fig. 7] Figure showing the appearance of platinum particles in SnO2-containing glass. [Fig. 8] Figure showing the appearance of platinum particles in SnO2-containing glass.

[0062] Examples Refining treatment of aluminosilicate glass according to the prior art Corrosion of Precious Metal Parts An aluminosilicate glass containing more than 200 ppm of tin oxide was melted and subjected to a refining treatment. In this case, noble metal parts were used. A refining tube made of PtRh10 was used and tested after 4 months of use. Experiments were conducted using Glass 1 in the following table. In another example, experiments were conducted using Glass 2.

[0063] The glass compositions without a fining agent are shown in the following table:

Table 6

[0064] Inside the tube, the noble metal of the tube was attacked and corroded, there were holes filled with glass, and tin oxide was deposited on the noble metal. The material of the tube showed cracks oriented along the grain boundaries and initial cracks on the cross-section.

[0065] FIG. 1 (Massalski, TB. Binary Alloy Phase Diagrams, Vol.2, Metals Park, Ohio: American Society for Metals, p. 1910) shows the phase diagram of platinum and tin. Tin forms various eutectic compositions with platinum at melting points of 1365°C and 1070°C. The inventors presume that the formation of alloy phases between the noble metal and tin is the cause of the damage.

[0066] The following table shows the results or observations in detail. Four samples from different sections of the same tube were examined: [Table 7]

[0067] In FIGS. 2 to 6, the light gray portions indicate parts of the clarification tube. In FIGS. 2 and 4 to 6, the dark portions indicate the glass in contact with the clarification tube. FIG. 2 shows cavities filled with SnO2 (dark portions of the clarification tube) and detached noble metal particles in a part of the clarification tube altered by corrosion. FIG. 3 shows cavities filled with SnO2 in the noble metal. FIG. 4 shows cavities filled with SnO2 and detached noble metal particles in a part of the clarification tube altered by corrosion. FIG. 5 shows detached noble metal particles and already detached noble metal particles in a part of the clarification tube altered by corrosion. FIG. 6 shows SnO2 needles in a part of the clarification tube altered by corrosion. These data indicate that SnO2 is involved in the formation of defects in the noble metal tube and that considerable corrosion occurs with the introduction of platinum particles into the glass.

[0068] Precious Metal Particles Contained in the Final Product As shown previously, when SnO2 is used in the glass, intense corrosion occurs and noble metal particles detach from the noble metal parts. Therefore, particles may be detected in the final product.

[0069] Figures 7 and 8 show the state of platinum particles in SnO2-containing glass. It appears that the noble metal particles are melted in the melt and then precipitated in the glass later. The size of these particles is usually 60 μm or less, and in many cases much smaller than this, for example about 5 μm. For specific applications, such particles do not pose a problem. However, when such particles occur in thin glass, especially near the surface, the surface bulges at the defective part and the defect becomes more visible, so that the particles are particularly conspicuous. Therefore, a defect much larger than the particles themselves occurs. During manufacturing, 10 - 30% of defective products are generated.

[0070] Defoaming treatment of aluminosilicate glass In order to investigate the defoaming effect, various melting experiments were carried out using Glass 1 with the above composition. In another example, a melting experiment using Glass 2 was carried out. A comparison was made between different amounts of alternative defoaming agents and SnO2 as a reference substance. Hereinafter, the defoaming agent (LM) is shown in units of weight%.

[0071]

Table 8

[0072] In the table, “+” represents good defoaming results, “++” represents excellent defoaming effects. “0” represents unsatisfactory defoaming effects, and “-” represents very poor defoaming effects. T1 represents the melting temperature, and T2 represents the defoaming temperature. t1 and t2 represent the melting time or the defoaming time.

[0073] Surprisingly, the fining results at 1650 °C using chloride were comparable to those using SnO2, that is, it was found that the same number of residual bubbles were confirmed in the melting crucible. Furthermore, at a lower fining temperature (here 1630 °C), the results using chloride were even better than those of the reference SnO2, and at an even lower fining temperature (here 1600 °C), it was surprisingly much better than the SnO2 modification example. Thus, a fining agent for aluminosilicate glass that gives better results than the conventional standard fining agent SnO2 at a lower temperature was found. Naturally, the energy consumption of the glass melt decreases accordingly, and the corrosion of the materials of the melting tank is also reduced. Also, from these results, it was found that using chloride as a fining agent greatly expands the process window and makes the manufacturing results less susceptible to variations in manufacturing parameters.

[0074] Since it was the common view of experts that the release of the fining gas should be as close as possible to the fining viscosity, this result was surprising. The boiling point of NaCl is 1465 °C, and the fining viscosity of the glass tested here is reached in the temperature range of 1550 °C to 1650 °C. Therefore, NaCl should originally release too much fining gas too early and the fining action should become weak. The opposite is also true.

[0075] Melting test in the manufacturing apparatus Since the results in the laboratory were very good, a corresponding melting test was carried out in the manufacturing apparatus. In this case, first, without changing the overall temperature control, only the fining agent SnO2 was replaced with NaCl. The starting amount of chloride was 0.5% by weight. This value was also determined for the laboratory melt.

[0076] The contents of SnO2 and Cl were measured daily by X-ray fluorescence analysis. After 5 days, the fining agent was replaced. At this stage and for several days thereafter, no change in bubbles was detected. Bubbles are an important indicator of whether the fining of the glass is successful. Thus, the change of the fining agent was successfully completed, and it was possible to proceed to the next step of further optimization. The amount of cullet used, the amount of fining agent, and the fining temperature were varied to determine the process window that enables the best production without glass defects.

[0077] In this way, in the manufacturing apparatus, aluminosilicate glass could be produced at a cullet ratio of 0 to 50%, a fining agent ratio of 0.25 to 0.70 wt%, and a fining temperature of 1550 to 1620 °C without significantly changing the number of bubbles.

[0078] After 5 days, a desirable decrease in platinum particles also occurred, decreasing from 15 to 20 particles per kg of glass to 1 to 3 particles.

Claims

1. A glass article composed of an alkali metal oxide-containing aluminosilicate glass having at least one halogen with a fining action in a proportion in the range of 500 to 8000 ppm and an Sn content of less than 500 ppm, wherein the glass has less than 100 ppm of As and less than 100 ppm of Sb, the glass article has a thickness of less than 250 μm, the platinum particles having a diameter of more than 5 μm in the glass article are 5 or less per 1 kg of the glass, the aluminosilicate glass contains at least 9 wt% of Na₂O, and the aluminosilicate glass has a quotient A in the range of 1.5 to 8.5, wherein 【Number 1】 holds, where m Ａｌ２Ｏ３ is the weight fraction in units of wt% of Al in the aluminosilicate glass ２ O ３ ; m Ｒ２Ｏ is the total of the weight fractions in units of wt% of the alkali metal oxides Na ２ O, K ２ O, and Li ２ O; m ＲＯ is the total of the weight fractions in units of wt% of the alkaline earth metal oxides MgO, CaO, BaO, and SrO; m Ｃｌ is the weight fraction in units of wt% of chlorine; m Ｉ is the weight fraction in units of wt% of iodine; m Ｂｒ is the weight fraction in units of wt% of bromine, a glass article.

2. The glass article according to claim 1, wherein the platinum particles having a diameter of more than 5 μm in the glass article are 3 or less per 1 kg of the glass.

3. The glass article according to claim 1 or 2, wherein the glass article has a thickness of less than 200 μm.

4. The glass article according to any one of claims 1 to 3, wherein the halogen having a fining action is selected from chlorine, bromine, iodine, and combinations thereof.

5. The glass article according to any one of claims 1 to 4, wherein the aluminosilicate glass has less than 100 ppm of boron and / or less than 500 ppm of lithium.

6. The glass article according to any one of claims 1 to 5, wherein the aluminosilicate glass has fluorine in a proportion in the range of 0.05 to 0.5 wt% in addition to the halogen having a fining action.

7. The glass article according to any one of claims 1 to 6, wherein the aluminosilicate glass contains the at least one halogen having a fining action in a proportion in the range of 500 to 5000 ppm and / or the Sn content is less than 100 ppm.

8. The glass article according to any one of claims 1 to 7, wherein the aluminosilicate glass contains the at least one halogen having a fining action in a proportion of at most 2500 ppm.

9. The aluminosilicate glass is chemically curable, particularly at a diffusion rate of at least 14 μm ２ / h and is chemically curable. The glass article according to any one of claims 1 to 8

10. The temperature T in °C when the aluminosilicate glass exhibits its fining viscosity Ｌ and the temperature T in °C of the boiling point of NaCl Ｓ（ＮａＣｌ） The ratio of these is at most 1.

2. The glass article according to any one of claims 1 to 9

11. The aluminosilicate glass has the following components: 【Table 1】 The glass article according to any one of claims 1 to 10.

12. The aluminosilicate glass has a β-OH content of up to 0.32 mm －１ The glass article according to any one of claims 1 to 11, having a β-OH content of

13. The aluminosilicate glass has less than 0.0001% by weight of NH ４ ＋ The glass article according to any one of claims 1 to 12, having the above properties.

14. The aluminosilicate glass has a cooling state corresponding to a cooling rate exceeding 300 °C / min in a temperature range from a temperature 50 °C higher than the glass transition temperature Tg to a temperature 100 °C lower than Tg, the glass article according to any one of claims 1 to 13.

15. Use of the glass article according to any one of claims 1 to 14 in a wearable terminal device, particularly a mobile phone, a tablet computer or a smart watch.

16. A method for manufacturing a glass article, comprising: - providing a batch for an alkali metal oxide-containing aluminosilicate glass having an Sn content of less than 500 ppm; - melting the batch to obtain a melt; - fining the melt by utilizing the fining action of at least one halogen; - shaping the glass article wherein the glass article has a thickness of less than 250 μm, the number of platinum particles having a diameter exceeding 5 μm in the glass article is 5 or less per kg of the glass, the aluminosilicate glass contains at least 9 wt% of Na2O, and the aluminosilicate glass has a quotient A in the range of 1.5 to 8.5, wherein 【Number 2】 is satisfied, where m Ａｌ２Ｏ３ is the weight fraction in units of wt% of Al ２ O ３ in the aluminosilicate glass, m Ｒ２Ｏ is the total of the weight fractions in units of wt% of the alkali metal oxides Na ２ O, K ２ O, and Li ２ O, m ＲＯ is the total of the weight fractions in units of wt% of the alkaline earth metal oxides MgO, CaO, BaO, and SrO, m Ｃｌ is the weight fraction in units of wt% of chlorine, m Ｉ is the weight fraction in units of wt% of iodine, m Ｂｒ is the weight fraction in units of wt% of bromine, method.

17. The method according to claim 16, wherein the temperature in °C when performing the fining treatment of the melt is at a ratio of at most 1.2 with respect to the boiling point in °C of the halogen compound used.

18. Providing a batch for an aluminosilicate glass having an Sn content of less than 100 ppm, the method according to claim 16 or 17.

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