TW201109286A - Glass plate for display device - Google Patents

Abstract

Disclosed is a chemically reinforced plate glass which is improved in brittleness inherent in glasses and is prevented from the occurrence of the extension of unavoidable remaining cracks that are formed during processing, and in which a deep surface stress layer is likely to be produced to enable the easy incorporation of the remaining cracks into the surface stress layer and scratches are hardly formed by external forces. The chemically reinforced plate glass contains (in terms of oxide contents by mass) 75.5 to 85.5% of SiO2, 1 to 8% of MgO, 0 to 7% of CaO, 0 to 5% of Al2O3, and 10 to 22.5% of Na2O, wherein the content of MgO is higher than that of CaO, the total content of MgO and CaO (MgO+CaO) is 8% or less, the total content of MgO, CaO and Na2O is 24.5% or less, and the ratio calculated by dividing the (MgO+CaO) value by the Na2O content is 0.45 or less.

Description

201109286 VI. Description of invention:

C. The present invention relates to a glass plate for a cover glass, a substrate glass or the like for a small display device, which typically has a mobile phone, a personal digital assistant (PDA) ) and touch panels, etc. C 冬好] Background Art In recent years, in mobile devices such as mobile phones and PDAs, the use of a protective display and an improved aesthetic cover glass (protective glass) have been increasing. Such a cover glass is widely used for chemically strengthened soda-lime glass (for example, refer to Patent Document i). 〇Prior Art Document Patent Document Patent Document 1: 曰本特开第2007-11210号 C ^ SUMMARY OF THE INVENTION SUMMARY OF THE INVENTION The problem to be solved by the invention is to provide a hole having a function such as a speaker for the cover glass, and to tend to have a complicated shape in design. Therefore, it is often the case that complicated machining such as drilling or curve carving using a drilling machine is performed during processing to complete the final shape. Therefore, in addition to the cracks generated during use, the peeling at the time of processing also becomes a cause, and there is a tendency to easily leave a large crack. When such a glass having residual cracks remaining during processing is strengthened, if 201109286 reaches the internal tensile stress of the slope, the strength is lowered. Further, since the cover glass has many opportunities for contact with foreign materials such as stones on the surface of the glass, there are many opportunities for scratches or defects. According to these examples, it has not been known that there is a breakage suitable for the rupture of the cover glass as a mobile device. On the other hand, this kind of portable information device requires a lightweight, ^匕 〇 j^~| 11 t, and the cover glass used for display protection is also required to be thin. However, if the thickness of the second cover is thin, the strength will be lowered, and the cover glass itself may be broken due to the use or falling in the middle, and the soft guide may not function to protect the display device. The problem arises. In order to solve the above problems, it is considered to increase the strength of the cover glass, and the method of forming a compressive stress layer on the surface of the glass as a p method is generally a method of forming a compressive stress layer on the surface of the glass, and is weathered (physical strengthening). Method) and chemical strengthening method are representative: air-cooling strengthening method: heating to soften the surface of the glass plate, and cooling and cooling, etc., to the rapid cooling system, the temperature is below the glass transition point. The ion on the surface of the glass plate is replaced by a small metal ion (typically Ϊ = = :): ion), which is exchanged for a larger ion radius (typically as described above for the % of the cover) The degree requirement is to be thin. If the air-cooling method is used for the thin glass crucible, it is difficult to form a compressive stress layer because the 厌η right 耵溥 耵溥 厌 厌 麻 麻 麻 麻 麻 麻 麻 麻 麻 麻 麻Strengthening the strength characteristics of Μ. Therefore, it is used for the display protection of 201109286. The chemical strengthening method is suitable for strengthening thin glass sheets. According to the chemical strengthening method, one side is used. The surface may form a surface compressive stress layer on both surface sides of the sheet thickness direction of the glass sheet, and on the other hand, an internal tensile stress layer which is in balance with the stress of the surface compressive stress layer is formed between the surface compressive stress layers. A thinner glass plate uses a chemical strengthening method to obtain a glass sheet of higher strength, and when the surface pressure is to be increased, the internal tensile stress generated to obtain a balance with a high surface compressive stress also becomes large. If the internal tensile stress is large, when the crack is deeper than the surface compressive stress layer, the force of pulling the front end of the crack is large, and the phenomenon of spontaneous pulverization and rupture of the glass occurs. If the internal tensile stress is reduced, it is only necessary to reduce the depth of the surface compressive stress layer. However, the defect or the crack becomes extremely weak, and the strength of the (four) is not obtained. A glass that forms a moderate stress distribution. As far as the glass used in the outer casing of a mobile device is used, the glass as described above is chemically strengthened. However, Na (4) Although the glass can have sufficient surface compressive stress of 50G 7GGMPa on the other hand, it is difficult to compress the depth of the stress layer on the surface. X, the brittleness index described later in Sodium silicate glass (4) Chekas 2, is a large value, easy' The cracking of the 'recurrence' will have occurred - the problem of the rapid extension of the crack. The other side of the eclipse is the cover glass *I, ', because of the use of acid salt If the compressive stress becomes too large and the slave obtains a deep surface compressive stress layer, then (4) the tensile stress will become larger than 201109286, and there is a problem that spontaneous and explosive cracking easily occur. The object of the present invention is to provide a chemical Reinforced flat glass, which improves the fragility of the glass itself, prevents the inevitable extension of residual cracks generated during processing, and can be easily produced by making the deep surface compressive stress layer easy to obtain. The residual crack is incorporated into the surface compressive stress layer, and it is not easy to cause scratches caused by external force. Moreover, an object of the present invention is to provide a flat glass for chemical strengthening which does not become excessively large by surface compressive stress. Even when a compressive stress layer is applied to a thin flat glass, the internal tensile stress is not easily increased. It is difficult to cause spontaneous rupture. Means for Solving the Problem The present inventors have provided a flat glass for chemical strengthening, which is represented by the following oxides and is represented by mass%, and contains 75.5 to 85.5% of SiO 2 , 1 to 8% of MgO, and 0 to 7% of CaO. 0 to 5% of Al2〇3 and 10~22.5% of Na20, wherein the content of MgO is more than that of CaO, and the sum of MgO and CaO content (MgO+CaO) is 8% or less 'the sum of MgO, CaO and Na20 content It is 24.5% or less, and the ratio of (MgO + CaO) divided by the content of Na20 is 0.45 or less. In the present specification, "~" is not specifically defined, and the numerical values described before and after it are used as the lower limit and upper limit. Further, the above-mentioned flat glass for chemical strengthening is provided, which contains K20 or Li20, wherein the sum of Na20, Κ20 and Li20 content (Na20+K20+Li20) is 23.5% or less, (Mg0+Ca0)+(Na20+K20+ Li2〇) When it is 24.5% or less, (Mg0+Ca0)/(Na20+K20+Li20) is 0.45 or less. Further, the above-mentioned flat glass for chemical strengthening is provided, wherein the Vickers hardness 201109286 (Vickers hardness) Hv is divided by the ratio obtained by breaking the blade edge value Kc, that is, the brittleness index value B is 6000 m 1/2 or less. Further, the above-mentioned flat glass for chemical strengthening is provided, wherein the density is 2.41 g/cm3. Further, the above-mentioned flat glass for chemical strengthening is provided, wherein the viscosity is 100 poise (100 dPa, s) and the temperature is 1800 ° C or lower. Further, a glass plate for a display device obtained by chemically strengthening the flat glass for chemical strengthening is provided. The inventors of the present invention have a flat glass composition which is extremely less likely to be scratched than the conventional soda lime glass and has a density of typically 2.41 g/cm 3 or less (a typical soda lime glass density is about 2.49 to 2.52 g/cm 3 ). The present invention has been observed by a glass composition obtained by chemically strengthening the glass to obtain a surface compressive stress layer of 30# m or more and obtaining a surface compressive stress of 300 to 600 MPa. EFFECT OF THE INVENTION The elongation of cracks during processing or at the time of use can be suppressed, and the surface compressive stress formed by chemical strengthening can suppress the elongation of cracks, and the risk of glass cracking when using a mobile device can be reduced. [Solid package method J. Embodiment of the invention The thickness of the glass plate of the present invention is typically 0.2 to 1.0 mm. From the point of view of practical strength, if the glass plate of less than 0.2 mm is chemically strengthened, it may not be able to satisfy its doubts. It is preferable that the glass plate for chemical strengthening of the present invention is chemically strengthened to obtain a surface compressive stress depth of 7 201109286 of more than 30 / / m. If it is 30/m or less, there is a fear that the micro crack will be generated in the tensile stress layer and there is a fear that it will be easily broken. The surface compressive stress of the glass sheet of the present invention is typically 3 MPa or more and 600 MPa or less. If it is less than 300Mpa, the necessary strength cannot be obtained, and there is a fear that the bending may be easily broken. The method for producing the glass plate for chemical strengthening according to the present invention (hereinafter referred to as the glass plate of the present invention) is not particularly limited. For example, various materials are blended in an appropriate amount, heated to about 1400 to 1800 ° C to be melted, and then defoamed and stirred. After homogenization, it is formed into a plate shape by a widely known float method, a down draw process, a press method, etc., and is slowly cooled, and then cut and ground according to a desired size. Processed and manufactured. In the case of the chemical strengthening method, there is no particular limitation if the nano ions in the surface layer of the glass sheet and the ions having a larger ionic radius than the sodium ions in the molten salt (typically, ions are discharged) are not particularly limited. For example, a method of immersing a glass plate in a molten molten potassium nitrate molten salt is exemplified. The condition for forming a chemical strengthening layer (surface compressive stress layer) having a desired surface compressive stress on a glass plate varies depending on the thickness of the glass plate, and typically the glass plate is impregnated with potassium nitrate. The solution is 2 to 10 hours, and the temperature of the potassium nitrate solution is below the strain point temperature of the glass plate, specifically 350 to 550 °C. Next, the composition of the glass plate of the present invention will be described by mass%.

Si〇2 is a main component forming a network structure of the glass sheet. If the content of si〇2 201109286

. Also, if it is over 76_5%. Further, the mesh structure is weak, and the density is not good, and it is difficult to produce a homogeneous one for the flat plate, and the content of the SiO 2 is a small file. If it is 82% or less, especially 79% or less, it is particularly suitable for production by the method of (4) which is carried out by a domain mold device such as heating H heating. It is φξ: 鬲k resistance, it is better to increase the content of the element number. The soil metal oxide has the effect of hindering ion exchange, but increasing the content of the multi-element number can alleviate the effect. Therefore, in comparison, the far side effect of Mgo and CaO is small, and further, Mg 〇 is smaller than Ca 〇. From these viewpoints, it is necessary to make the content of Mg 较 more than the content of Ca 。. Therefore, Mg 〇 is a main component, specifically, MgO is 1 to 8%, and CaO is not necessarily required, but may be appropriately contained within a range of up to 7%. Although the sum of the contents of MgO and CaO is 8% or less, it is preferably 1.5% or more and 7.5% or less. Typically, MgO is from 1 to 7.5% and CaO is from 0 to 6.5%. Further, in the present invention, when the range of the content of a certain component is described as "〇~", it means that the component is not contained.

MgO and CaO are useful components for improving solubility and improving chemical durability such as alkali resistance, and contain at least 1% or more of MgO as described above. On the other hand, even when CaO is contained, in order to obtain sufficient scratch resistance, the sum of the contents of MgO and CaO (hereinafter referred to as RO) is 8% or less.

Na2 is ion exchanged to form a surface compressive stress layer, and it is necessary for 201109286 to improve the glass meltability. Therefore, it may contain 10 to 22.5% of Na20. It is preferably 11.5% or more. If it exceeds 22.5%, it is liable to cause crystallization or to easily reduce chemical resistance. Although K20 is not necessary, the ion exchange rate in chemical strengthening is increased to obtain a desired surface compressive stress and surface compressive stress layer depth, which may be up to 10%.

Although LhO is not necessary, it can also be used to increase the ion exchange rate to 10°/. until. However, from the viewpoint of increasing the cost of raw materials, when LhO is contained, it is 2. /. The following is preferred, and it is more preferable that it is substantially not contained. When at least one of K2〇 and Li20 is contained in order to improve solubility, etc., the sum of the contents of the above (2〇+1 (:2〇+1^2〇) is preferably from 11.5 to 23.5%. If less than 11.5 There is a fear that the solubility cannot be sufficiently improved. If it exceeds 23%, it is likely to cause crystallization or to reduce chemical resistance. Further, (Na2〇+K2〇+Li2〇) is expressed as R2〇. When chemical resistance is required, r2〇 is preferably 21.5% or less, more preferably Na20 is 10 to 21.5%, K20 is 〇~1〇%, and Li20 is 〇~1〇〇/0. If MgO, CaO When the total content of the Na2 bismuth content is more than 24.5%, sufficient scratch resistance cannot be obtained, that is, the brittleness index value B is less likely to be (9) (9), preferably 23.5% or less, more preferably 225% or less. When one of the above CaO 'K2〇 and Li20 is used, r〇+r2〇 is preferably 24.5% or less. If it exceeds 245%, there is a fear that sufficient scratch resistance may not be obtained, and it is more preferably 23.5. Below, the optimum is 22.5% or less. The ratio of RO to Nae content, *R〇/Na2〇 exceeds 〇45, the scratch resistance is lowered. [S1 10 201109286 RO to R2〇 ratio It is preferable that R〇/R2〇 is 0·45 or less. If it exceeds 〇·45, there is a fear that the scratch resistance is lowered. Further, when H〇+R2〇 is 24 5 or less, RO/R2〇 is caused. It is preferable that it is 0.45 or less. Although Α1ζ〇3 is not necessary, the chemical durability of the flat glass can be remarkably improved by a small amount of addition, and it is useful for improving ion exchange rate and suppressing phase separation. When the content is 80 丨 2 〇 3, the content is preferably 1% or more. On the other hand, excessive addition causes deterioration of scratch resistance, so the content is preferably 4 ° / or less. The glass is essentially composed of the above-mentioned components, and may contain other components within the range not impairing the object of the present invention. Further, in this case, the total content of the above components is preferably 90% or more. The component which can be contained in the glass plate of the present invention can be exemplified as follows. For the purpose of homogenization, coloration, control of infrared ray transmission energy, and ultraviolet ray transmission energy of the entire plate glass, Fe, Ni, and Se may be added. , Co, Ce, etc. Further, in order to make it easier to manufacture a relatively homogeneous flat glass, a conventional clarifying agent may be added. Related clarifying agents are S〇3, CBu Sb2〇3, Sn〇4. However, from the aspect of environmental impact In addition, clarification is preferably carried out in the range of S03. Further, ZnO may be appropriately added to the extent that the effects of the present invention are not impaired. Further, SrO, Ba〇, b2 may be contained within a range not impairing the effects of the present invention. 3, etc., but for the purpose of the present invention, it is typically less than 0.5% relative to the entire flat glass. The Vickers hardness Hv of the flat glass of the present invention is divided by the fracture toughness value Kc and 11 201109286, that is, the brittleness index value B is preferably 6000 π 1/2 or less. If it exceeds 6000 m"/2, the scratch resistance of the glass becomes insufficient, and it is more preferably 5800 m_l/2 or less.

Further, in the present invention, the fragile index value B (B R ) proposed by Lawn et al. is used as an index of the fragility (scratch resistance) of the glass.

Lawn and D.B. Marshall, J. Am. Ceram. Soc., 62 [7-8] 347-350 (1979)). Here, the fragile index value B is defined by the formula (1) from the Vickers hardness hv of the material and the fracture toughness value Kc. B=Hv/Kc (1) If the size of the Webster indentation hitting the glass surface is used and the formula (2) is used, the brittleness B of the glass can be easily evaluated. Here, p is the embossed load of the Indenter and the length of the diagonal of the Wechs indentation and the length of the crack generated from the four corners (the moment containing the indenter) The full length of the two symmetric cracks). c/a = 0.0056B2 / 3P, /6 (2) The density p of the plate glass of the present invention is preferably 2.41 g/cm3 or less. If it exceeds 2.41 g/cm3, there is a fear of reducing the scratch resistance. Further, the density is typically measured at room temperature around 23 °C. The viscosity of the flat glass of the present invention is 1〇〇0^.8 (1 (^77 = 2) is preferably 1800 ° C or less, more preferably 168 〇. 匸 below. The flat glass of the present invention is equivalently It has meltability and can be applied to various production methods. For example, a raw material is blended according to a conventional method to be a target composition, and it is heated to 1450 to 1650 ° C for vitrification. Second, the molten glass is shaped after clarification. The shape is desirably cooled to become a flat glass [S1 12 201109286 . - Embodiments Next, the present invention will be more specifically described by way of Examples and Comparative Examples, but the present invention is not limited by the following examples. (1) The examples (Example 1) and Comparative Example (Example 2) of the flat glass of the present invention, which are represented by mass%, are shown in the block from SiO 2 to Κ 20. The powder of 200 g of the raw material blended is put into platinum. After that, the mixture was heated and dissolved in an atmosphere of 1450 to 1650 ° C for 4 hours, and the glass of each composition which had been uniformly dissolved was poured into a carbon mold to form a square flat plate having a side length of about 10 cm and a thickness of about 5 mm, and was cooled. The obtained glass is at 490~570°C After slowly cooling, after removing the stress, it was cut and ground to obtain a square sample having a side length of 2 cm and a thickness of 4 mm. Table 1 shows the density P (unit: g/cm3) of the same glass, and the brittleness index value B. (Unit: m_1/2), wear depth D (unit: m), viscosity as a solubility index, temperature T2 of 100 dPa*s (unit and viscosity is temperature T4 of l〇〇〇〇dPa.s. Brittleness The index value is determined as follows. That is, in order to remove the surface residual stress formed by the grinding, the sample polished to the mirror surface is heated (100 C/hr) to a temperature higher than the strain point of the glass by 50 ° C. The temperature was maintained for 3 hours and then slowly cooled (60 ° C / hr). Thus, the brittleness was measured in the state where the thermal strain and the processing strain of the surface were almost completely removed. The brittleness was measured using the Vickers hardness. Test machine. Using the same test machine, 10 indentations were applied to the surface of the glass, using the previous formulas (1) and (2), using the average length of the cracks generated from the four corners of the indentation and the Wechs indenter The load is embossed to calculate the fragile 13 201109286 index value B. The embossed load is 5 kgf. The degree P is calculated from the dry mass of the sample at 23 ° C and the mass in water according to the Archimedes method. The measurement is performed using a high-precision scale that can be measured up to 1 # g and the effective number is calculated. After the 5 digits, the last digit is rounded to 4 digits. The depth of wear D is first sandblasted for 2 minutes at a pressure of 1 kgf/cm2 in a circular area of 2 cm in diameter of the flat glass (sandblast) In the embodiment of the present invention described in the table, it can be seen that the destructive kinetic value Kc after the chemical strengthening treatment is also increased, and the external force can be suppressed. The extension of the resulting crack. Further, when the Vickers indenter is embossed to the flat glass, the crack generates a load (when the load is gradually increased, the load of the crack is first generated from the four corners of the indentation) is 1 OOOOgf', and the flat glass is subjected to the following method. The example of the flat glass is scientifically strengthened. The crack generated by the same method as the conventionally modified sodium glass has a load of 2000 gf (the brittleness index B of 6800 m when not strengthened), and the crushing load is increased to 5 times by improving the brittleness. These glasses were subjected to chemical strengthening treatment as described below. That is, the glass was individually immersed in 40 (potassium nitrate molten salt of TC for 1 hour to carry out chemical strengthening treatment. For each glass, a surface stress meter FSM-_0 manufactured by Ohara Co., Ltd. was used to measure surface compressive stress. s (unit: inspection) and the thickness t of the surface compressive stress layer (unit: (4). The surface compressive stress depth of the scratch resistant glass is 4 times that of the general soda lime glass of Example 2, on the other hand, it is known If the surface compressive stress value is below 6 〇〇Mpa, it is an appropriate value. 201109286 Furthermore, it is clear that the Kc after strengthening is also increased. Moreover, the size of the indentation when Kc is embossed with a Wechs indenter and The length of the crack generated from the four corners of the indentation is obtained by the above formula (1) and the former formula (2). [Table 1] Example 1 ~mz S i Ο 2 7 7.6 7 3 . 〇A 1 203 3 . 4 1 . 8 M g Ο 2 . 7 3. 7 C a Ο 0 . 9 .7.8 N a 2 Ο 13.6 13.0 K 2 Ο 1 . 8 〇. 7 Ρ 2 . 3 9 5 2 . 5 Β 5 2 0 0 7 10 0 D 16 2 1 Τ 2 16 8 0 14 6 0 Τ 4 112 0 10 4 0 S 4 2 5 6 8 0 t 3 9 1 0 Enhanced Κ C 1.18 1 〇. 9 8 Industry The possibility of utilizing the present invention The flat glass for chemical strengthening is used for improving the fragility of the glass itself, making it less prone to spontaneous cracking and reducing the damage caused by external force, and can be used for covering the material display device, etc. In addition to the portable information device, etc., for example, a liquid crystal television type television, in particular, a large-scale thin television on the 17th phase, etc., and the Japanese Patent Application No. 2009- filed on July 16, 2009 The entire contents of the specification, the scope of application, and the abstract of 167898 are hereby incorporated herein by reference in its entirety in its entirety in its entirety in its entirety in [Main component symbol description] (none) t si 16

Claims (1)

201109286 VII. Patent application scope: 1. A flat glass for chemical strengthening, which is characterized by the following oxides and expressed by mass%, containing 75.5 to 85.5% of SiO 2 , 1 to 8% of MgO, 0 to 7%. iCaO, 0~5% iAl2O3 & 10~22.5% iNa2〇, wherein the content of MgO is more than that of CaO, the sum of MgO and CaO content (MgO+CaO) is 8% or less, and the sum of MgO, CaO and Na20 is 24.5% or less, and the ratio obtained by dividing the content of MgO and CaO (MgO + CaO) by the content of Na20 is 0.45 or less. 2. The flat glass for chemical strengthening according to claim 1, which contains K20 or Li20, wherein the sum of Na20, K20 and Li20 (Na20+K20+Li20) is 23.5. /. Hereinafter, the content of MgO and CaO (MgO+CaO) and the content of Na20, K20 and Li20 (Na20+K20+ > Li20) are 24_5% or less, and the content of MgO and CaO (MgO+CaO) is divided by Na20 and K20. The ratio of Li20 (Na20+K20+ Li20) was 0.45 or less. 3. The flat glass for chemical strengthening according to claim 1 or 2, wherein the Vickers hardness Hv is divided by the damage duty value Kc, that is, the brittleness index B is 6000 m_1/2 or less. . 4. The flat glass for chemical strengthening according to the first, second or third aspect of the patent application, wherein the density of the flat glass is 2.41 g/cm3 or less. 5. The flat glass for chemical strengthening according to the scope of claim 1, 2, 3 or 4, wherein the viscosity of the flat glass is lOOdPa.s and the temperature is 180 (TC or less. 6_-type glass plate for display device) It is obtained by chemically strengthening the flat glass for chemical strengthening according to any one of the items 1 to 5 of the patent application No. 17 201109286. m 18 201109286 IV. Designated representative figure: 〇 (none) (1) Representative representative figure of the case For: () (2) A brief description of the symbol of the representative figure: (none) 5. If there is a chemical formula in this case, please disclose the chemical formula that best shows the characteristics of the invention: