TW201302633A - A method of manufacturing a cover glass blank for electrical device and a method of manufacturing a cover glass for electrical device - Google Patents

Abstract

The objective of the present invention is to provide a method for producing a cover glass blank for an electronic device suitable for small-volume production in great varieties and a method for producing a cover glass for an electronic device. The method for producing a cover glass blank for an electronic device including a forming step of performing press forming of a lump of molten glass using a pair of dies, wherein, on the basis of relation between a temperature difference at opposite positions of the pair of dies used in press forming of the molten glass and the flatness of glass blank obtained after the press forming, the temperature difference between the pair of dies with which a flatness required for a cover glass for an electronic device can be achieved is determined, and press forming is performed while the temperature of the pair of dies is controlled so that the temperatures of the pair of dies fall within the determined temperature difference.

Description

Method for producing protective glass blank for electronic equipment and method for producing protective glass for electronic equipment

The present invention relates to a method for producing a cover glass blank for an electronic device and a method for producing a cover glass for an electronic device.

In a portable device such as a mobile phone, a PDA (Personal Digital Assistant), a digital camera, a video camera, or the like as an electronic device, the main purpose of protecting the display screen is to use a protective glass for a portable machine. . In recent years, the demand for thinner and lighter portable devices, and the damage resistance, impact resistance, etc. of the portable device (the drop of the machine or the input according to the touch panel) In view of the demand, the protective glass for portable devices used as protective glass for electronic equipment is required to be thin and mechanically strong. Therefore, in order to satisfy these required characteristics, a glass substrate subjected to chemical strengthening is produced. A chemical strengthening of a plate glass containing a lithium ion or a sodium ion is disclosed, for example, in Patent Document 1.

In addition, conventionally, in the production of a cover glass for a portable device, a float molding method, a down-draw method, or the like is employed as a method of producing a sheet glass (or a glass substrate).

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2009-13052

In recent years, in addition to the thinning and high functionality of portable devices, it is also required to be able to produce a small amount of protective glass in accordance with the frame and display screen of portable devices of various shapes. Multi-item production. However, the floating molding method and the down-draw method described above are suitable for mass production of glass substrates of the same shape because they use a large-volume glass melting apparatus, but are not suitable for a small number of multi-product production.

On the other hand, a molding method suitable for a small amount of multi-item production of a sheet glass (glass blank) can be considered. A molding method generally known is a method in which a block of molten glass is supplied onto a lower mold, and a block (molten glass block) of molten glass is molded by an upper mold (vertical direct molding method). However, in this method, there is a problem that the flatness (shape accuracy) of the produced glass blank is poor.

The reason is as follows. In the vertical direct molding method, the lower mold is heated by the high-temperature molten glass block during the period from the time when the molten glass block is placed on the mold supported by the rotary table to the start of press molding. Therefore, heat is also easily transmitted to the rotating machine supporting the lower mold, so that the rotating machine is deformed by heat. As a result, the thickness deviation of the glass blank or the shape accuracy of the flatness or the like is lowered.

Further, in the vertical direct molding method, only after the molten glass block is placed on the lower mold, only the contact surface of the molten glass block with the lower mold and the portion close to the contact surface are rapidly cooled. Therefore, molded molding not long ago The viscosity distribution (temperature distribution) inside the molten glass block is in a wide range. That is, not long before the press molding, the difference in viscosity between the lower side and the upper side of the inside of the molten glass block becomes relatively large. When the press molding is performed in this state, an increase in the thickness deviation of the glass blank and a decrease in the flatness occur. The increase in the thickness deviation of the glass blank and the decrease in the flatness are caused by the time difference between the placement of the molten glass block on the lower mold and the start of the press molding, and the vertical direct molding method cannot be fundamentally suppressed. This situation.

Further, in the vertical direct molding method, in order to prevent the molten glass block from adhering to the lower mold and being removed, it is necessary to apply a solid lubricant such as BN (boron nitride) to the lower mold in advance. However, when the solid lubricant adheres to the glass blank, the transparency is deteriorated. Therefore, in order to improve the flatness and peel off the solid lubricant, the glass blank produced by the vertical direct molding method must have a processing step of the main surface in the subsequent step. Therefore, the conventional press molding method is not suitable for the production of a protective glass blank for an electronic device.

An object of the present invention is to provide a method for producing a protective glass blank for an electronic device which is suitable for production of a small number of items, and a method for producing a cover glass for an electronic device.

The present inventors have carefully studied the above problems, and the present inventors have considered a new method. That is, in the method for producing a glass blank of the present embodiment, it is adopted by: in relation to the molten glass block One of the pair of molds (molding molding) disposed in the direction orthogonal to the direction of the drop (horizontal direction), and the horizontal direct molding method of molding the molten glass block in the falling direction. In the horizontal direct molding method, the molten glass lump is not temporarily contacted and held at a lower temperature than the molten glass block until it is molded. This point is different from the conventional vertical direct molding method. Therefore, in the vertical direct molding method, the viscosity distribution inside the molten glass block becomes very wide at the time of press molding at the beginning of the press molding, whereas in the horizontal direct molding method of the present embodiment, The viscosity distribution of the molten glass block is kept uniform.

Therefore, compared with the vertical direct molding method, in the horizontal direct molding method, the molten glass block after press molding can be uniformly stretched uniformly. Therefore, as a result, it is extremely easy to fundamentally suppress the decrease in flatness when the glass blank is produced by the horizontal direct molding method as compared with the case where the glass blank is produced by applying the vertical direct molding method.

Further, when the temperature difference between the one of the molds at the opposing position is small when the molten glass block is molded, the flatness of the generated glass blank can be lowered as compared with the case where the temperature difference is large. In this case, when the temperature difference between the pair of dies is smaller, it is easier to achieve a heat balance when the molten glass block having a high temperature contacts the molded surface (inner peripheral surface) on the inner side of the mold and is cooled rapidly. Therefore, it is possible to more suppress the decrease in the flatness of the glass blank which may be caused by the difference in the degree of minute thermal deformation between one of the cooling stages. That is, there is a correlation between the temperature difference between the pair of molds at the opposite positions when the molten glass block is molded, and the flatness of the glass blanks obtained after the press molding.

If the correlation is known, the maximum value of the temperature difference (absolute value) between the ones of the molds required to realize the protective glass for electronic equipment can be known. Therefore, by controlling the temperature difference between the pair of dies to be equal to or lower than the maximum value, the flatness required for the cover glass for electronic equipment can be achieved.

From the above viewpoint, the present invention relates to a method for producing a protective glass blank for an electronic device, which comprises a method for producing a protective glass blank for an electronic device, which is formed by molding a block of molten glass using a pair of molds. The method is characterized in that: according to the relationship between the temperature difference between the mold at the opposite position of the molten glass and the flatness of the glass blank obtained after the press molding, the achievable electron is obtained. The temperature difference between the pair of dies of the flatness required for the protective glass for the machine is controlled so that the temperature of the pair of dies can be controlled within the temperature difference obtained as described above while controlling the temperatures of the pair of dies. forming.

In the method for producing a cover glass blank for an electronic device, preferably, in a press molding step, a temperature at a portion where the pair of the molds are in contact with each of the molten glass is the same temperature between the pair of molds Molded.

In the method for producing a cover glass blank for an electronic device, the temperature of the pair of dies from the block to the mold to be separated is set to a temperature at which the glass transition point (Tg) of the molten glass is not reached. .

In the above method for producing a protective glass blank for an electronic device, the thickness of the glass blank obtained by the above-described press molding step is made Molding is carried out in such a manner that the thickness of the protective glass for electronic equipment is the same thickness.

In the method for producing a cover glass blank for an electronic device, preferably, the method of cutting the molten glass to cause the block to fall toward the pair of molds is provided, and in the cutting step, the molten glass is used The cut marks are located on the periphery of the glass blank to cut the molten glass.

In the method for producing a cover glass blank for an electronic device, preferably, the step of cutting the molten glass to cause the block to fall toward the pair of molds is provided, and in the press molding step, the molten glass is melted. The molten glass is molded in the timing at which the cut marks protrude from the pair of molds.

In the method for producing a cover glass for an electronic device according to the present invention, the glass wool generated by the method for producing a cover glass for an electronic device is left in a state in which strain is generated. The glass blank is processed into a shape processing step of a shape of a cover glass for an electronic device.

A method for producing a cover glass for an electronic device according to the present invention, characterized in that a surface state of a main surface of a glass blank produced by the method for producing a cover glass blank for an electronic device is maintained to make the glass blank The main surface is a main surface of the cover glass for an electronic device, and a shape processing step of processing the outer peripheral shape of the glass blank into an outer peripheral shape of the cover glass for an electronic device is performed.

A method for producing a cover glass for an electronic device according to the present invention is characterized in that a cover glass for an electronic device is produced by using a glass blank for an electronic device obtained by the method for producing a cover glass for an electronic device.

According to the present invention, it is possible to manufacture a protective glass blank for an electronic device and a cover glass for an electronic device which are suitable for a small amount of multi-product production.

In the following embodiments, protective glass blanks for portable devices and protective glass for portable devices are used as protective glass blanks for electronic devices and protective glass for electronic devices, respectively. .

(1) First embodiment (1-1) Protective glass of the embodiment

The configuration of the cover glass of the present embodiment will be described with reference to Fig. 1 . In the first embodiment, (a) is a perspective view of a cover glass according to the present embodiment, and (b) is a cross-sectional view of the cover glass of the present embodiment.

The cover glass of the present embodiment is a glass substrate itself or a printed layer formed on the glass substrate (the latter structure is shown in Fig. 1). A preferred application form of the cover glass of the present embodiment is, for example, a cover glass for use in a display screen of a portable electronic device, particularly a mobile phone (portable device). Therefore, the cover glass of the present embodiment must have a thin and high-strength glass that satisfies the specifications corresponding to the drop of the machine or the operation input to the display screen (the operation input as the function of the touch panel). Therefore, the cover glass of the present embodiment is composed of a glass material containing an alkali metal oxide which can be chemically strengthened by ion exchange treatment.

For example, an aluminosilicate glass containing SiO ₂ , Al ₂ O ₃ , and an alkali metal oxide selected from at least one of Li ₂ O and Na ₂ O; or a soda-lime glass or the like can be preferably used. Known glass materials.

The aluminum silicate glass is particularly preferably contained in an amount of 62% by weight to 75% by weight of SiO ₂ or 5% by weight in terms of practicality such as manufacturability, mechanical strength, and chemical durability of the sheet glass. 15% by weight of Al ₂ O ₃ , 0-8 % by weight of Li ₂ O, 4% by weight to 16% by weight of Na ₂ O, 0 to 6% by weight of K ₂ O, and 0% by weight to 12% by weight of ZrO ₂ , with 0~6 wt% of MgO.

Referring to Fig. 1(b), a compressive stress layer 10U and a compressive stress layer 10V are formed in the surface layer portions on the front surface side and the inner surface side of the glass substrate 10 of the present embodiment. The compressive stress layer 10U and the compressive stress layer 10V are replaced by a part of an alkali metal originally contained in a glass material constituting the glass substrate, and are replaced by an altered layer of an alkali metal having a large ionic radius. For example, sodium ions contained in the glass material constituting the glass substrate of the present embodiment are replaced with potassium ions.

Further, the thickness of the compressive stress layers 10U and 10V can be appropriately selected depending on the use of the glass substrate, but from the viewpoint of ensuring the damage resistance of the main surfaces 10T and 10B and the impact resistance of the glass substrate 10, it is preferable. 10 μm or more, particularly preferably 30 μm or more, more preferably 40 μm or more. On the other hand, the upper limit of the thickness of the compressive stress layers 10U and 10V is not particularly limited. The glass substrate 10 is manufactured in the process of preventing the increase in the time required for the ion exchange treatment and the deterioration of the stress balance of the two main surfaces when the cutting is performed by the outer shape processing (cutting processing or wet etching). produced From the viewpoint of practical use such as spontaneous pulverization (self-explosion), etc., it is preferably 100 μm or less, and particularly preferably 70 μm or less. Further, the thickness of the compressive stress layer 10U may be different from the thickness of the compressive stress layer 10V. However, at this time, stress uniformity collapses on both main surfaces 10T, 10B of the glass substrate 10, and the glass substrate 10 is liable to cause warpage. Therefore, it is generally preferred that the thickness of the compressive stress layer 10U is almost the same as the thickness of the compressive stress layer 10V.

The thickness T of the glass substrate 10 is not particularly limited, and is preferably 1 mm or less, and particularly preferably 0.7 mm or less from the viewpoint of suppressing an increase in weight of various devices to which the glass substrate 10 is applied and a reduction in thickness of the device. The lower limit of the sheet thickness is usually preferably 0.2 mm or more from the viewpoint of ensuring the mechanical strength of the glass substrate 10.

The glass substrate 10 of the present embodiment may be composed only of the main body of the glass substrate 10 or, depending on the application of the glass substrate 10, as shown in Fig. 1, on either one of the main surfaces 10T and 10B of the glass substrate. On the surface, one or more decorative layers 20 are provided. The decorative layer 20 may, for example, be an optically functional layer such as (1) an AR coating (anti-reflective coating), an anti-glare coating, a semi-reflective coating, or a polarizing film, and (2) ITO (Indium Tin Oxide: The indium tin oxide) film is a layer having an electrical function such as a transparent electrode film, and (3) a layer having a function of improving aesthetics such as a printed layer, and the like. In addition, a function as a touch panel may be added to the glass substrate 10 by laminating a plurality of decorative layers 20 and performing pattern forming processing or the like.

(1-2) Method for manufacturing protective glass for portable machine of embodiment

Next, a method of manufacturing a cover glass for a portable machine will be described with reference to FIG. Fig. 2 is a flow chart showing the manufacturing steps of the cover glass for a portable machine.

As shown in Fig. 2, in the cover glass for a portable machine, first, a molten glass is molded in a press molding step to produce a glass blank (step S10). Next, the glass blank obtained by press molding is subjected to shape processing to produce a glass substrate having a desired shape (step S20). The glass substrate is then chemically strengthened to form a compressive stress layer on the surface portion of the glass substrate (step S30). Then, a decorative layer composed of a single layer or a plurality of layers may be provided on the surface layer of the glass substrate as necessary (step S40).

The steps are described in detail below.

(a) Molding step

Referring first to Fig. 3, a press molding step (step S10) will be explained. Figure 3 is a plan view of the apparatus used in the press molding. As shown in FIG. 3, the apparatus 101 is provided with four sets of molding units 120, 130, 140, and 150, and a cutting unit 160. The cutting unit 160 is provided on the path of the molten glass flowing out from the molten glass outflow port 111. The device 101 is configured to drop a block of molten glass (hereinafter also referred to as a paste ball) that can be cut by the cutting unit 160, and at the same time, the two sides of the path are dropped from the block to face each other. The block is clamped and molded, thereby forming a glass blank.

Specifically, as shown in FIG. 4, the device 101, with a molten glass flow The outlet 111 is centered, and four sets of molding units 120, 130, 140, and 150 are provided every 90 degrees.

The units of the molding units 120, 130, 140, and 150 are driven by a moving mechanism not shown in the drawings, and are retractable with respect to the molten glass outflow port 111. That is, it can be located at a trapping position directly below the molten glass outflow port 111 (in the third drawing, the position where the molding unit 140 is drawn by the solid line), and the exiting position away from the molten glass outflow port 111 (Fig. 3) The molding units 120, 130, and 150 are moved between the position depicted by the solid line and the position of the molding unit 140 depicted by the broken line.

The cutting unit 160 is disposed on the path of the molten glass between the collection position (the collection position of the paste ball by the molding unit) and the molten glass outflow port 111, and appropriately cuts off the flow outlet from the molten glass. The molten glass flowing out of 111 forms a block of molten glass. The cutting unit 160 has a pair of cutting edges 161 and 162. The cutting blades 161 and 162 are driven so as to intersect each other on the path of the molten glass at a certain timing. When the cutting edges 161 and 162 intersect, the molten glass is cut out to obtain a paste ball. The resulting paste ball is dropped toward the trapping position.

The press unit 120 includes a first mold 121, a second mold 122, a first drive unit 123, and a second drive unit 124. Each of the first mold 121 and the second mold 122 is a flat member having a surface for molding a paste ball. The normal directions of the two faces are substantially horizontal, and the two faces are arranged to face each other in parallel. The first driving unit 123 moves the first mold 121 forward and backward with respect to the second mold 122. On the other hand, the second driving unit 124 advances and retreats the second mold 122 with respect to the first mold 121. First driving unit 123 The second drive unit 124 has a mechanism that rapidly closes the surface of the first drive unit 123 and the surface of the second drive unit 124, such as a mechanism in which an air cylinder, a solenoid, and a coil spring are combined.

The construction of the molding units 130, 140, and 150 is the same as that of the molding unit 120, and thus the description is omitted.

After moving to the trapping position, each of the press units is driven by the first driving unit and the second driving unit, and the falling paste ball is sandwiched between the first mold and the second mold to form a predetermined thickness, and is rapidly formed. After cooling, a round glass embryo G is produced. Next, after the molding unit is moved to the exit position, the first mold and the second mold are pulled apart to drop the formed glass blank G. Below the exit positions of the press units 120, 130, 140, and 150, a first conveyor belt 171, a second conveyor belt 172, a third conveyor belt 173, and a fourth conveyor belt 174 are provided, respectively. Each of the first to fourth conveyor belts 171 to 174 receives a glass blank G dropped from the corresponding molding unit, and conveys the glass blank G to a subsequent step (not shown).

In the apparatus 101, the molding units 120, 130, 140, and 150 are configured to sequentially move to the trapping position, and move the paste ball to the exit position. Therefore, it is not necessary to wait for the cooling of the glass blank G in each of the press units, and the glass blank G can be continuously formed.

Fig. 4 (a) to (c) show the molding of the apparatus 101 more specifically. Fig. 4(a) is a view showing a state before the preparation of the paste ball, Fig. 4(b) is a view showing a state in which the paste ball is made by the cutting unit 160, and Fig. 4(c) is shown by the paste ball. A state in which the glass blank G is molded by molding.

As shown in Fig. 4(a), the molten glass material L _G continuously flows out from the molten glass outflow port 111. At this time, the cutting unit 160 is driven at a predetermined timing, and the molten glass material L _G is cut by the cutting edges 161 and 162 (Fig. 4(b)). Thereby, the molten glass after the cutting becomes a substantially spherical paste ball G _G due to the surface tension. The outflow amount per unit time of the molten glass material L _G and the driving interval of the cutting unit 160 can be appropriately adjusted depending on the size of the target glass blank G or the volume determined by the thickness.

The produced paste ball G _{G is} dropped toward the gap between the first die 121 and the second die 122 of the press unit 120. At this time, when the paste ball G _G enters the gap between the first die 121 and the second die 122, the first drive unit 123 and the first die 121 and the second die 122 are driven to approach each other. The second drive unit 124 (refer to Fig. 4). Thereby, as shown in FIG. 4(c), the paste ball G _G is captured (captured) by the first die 121 and the second die 122. In addition, the molding surface 121a of the first mold 121 and the molding surface 122a of the second mold 122 are in a state of being close to each other with a small gap, and are sandwiched between the molding surface 121a of the first mold 121 and the molding surface 122a of the second mold 122. The paste ball G _G is formed into a thin plate shape.

In order to maintain a constant interval between the molding surface 121a of the first mold 121 and the molding surface 122a of the second mold 122, projections are provided on the molding surface 121a of the first mold 121 and the molding surface 122a of the second mold 122, respectively. 121b and protrusion 122b. In other words, by causing the projections 121b and the projections 122b to abut each other, the interval between the molding surface 121a of the first mold 121 and the molding surface 122a of the second mold 122 can be kept constant to form a glass wool. The space of the shape of the embryo G.

The temperature adjustment mechanism (not shown) is provided in the first mold 121 and the second mold 122, and the temperature of the first mold 121 and the second mold 122 is maintained at a glass transition temperature (Tg) of the molten glass L _G . Full low temperature.

The temperature difference between the molding surface 121a of the first mold 121 and the molding surface 122a of the second mold 122 at the opposing position when the paste ball G _{G is} press-molded is between the flatness of the glass blank obtained after the press molding. There is a correlation. In other words, the temperature difference between the molding surface 121a of the first mold 121 and the molding surface 122a of the second mold 122 at the opposing position is smaller, and the flatness of the glass blank obtained after the press molding is better. This is because when the temperature between the pair of dies is relatively close, since the heat balance can be achieved when the high temperature paste ball G _G contacts the molding surface of the mold and is cooled rapidly, it is more possible to suppress the mold from one of the cooling stages. The difference in the degree of micro-thermal deformation between them may result in a decrease in the flatness of the glass blank.

Here, if the correlation is known, it is possible to know one of the flatness required for realizing the cover glass for the portable device to the mold (the molded surface 121a of the first mold 121 and the second mold 122). The maximum value of the temperature difference (absolute value) between the molded faces 122a). Therefore, by controlling the temperature difference between the pair of dies to be equal to or lower than the maximum value, the flatness required for the cover glass for a portable machine can be achieved. For example, when the flatness required for the cover glass for a portable device is 8 μm, the temperature difference between the pair of dies is controlled to be within 10 ° C, and compression molding is performed. The flatness of the glass blank produced when the temperature difference between the pair of dies was 0 ° C was the best. Only in response to the flatness required for protective glass for portable machines, The above temperature difference is appropriately determined in the correlation.

In the apparatus 101, the paste ball G _G comes into contact with the molding surface 121a of the first mold 121 or the molding surface 122a of the second mold 122, and the first mold 121 and the second mold 122 completely close the paste ball G _G. The time is very short, about 0.06 seconds. Therefore, the paste ball G _G is formed into a substantially circular shape along the molding surface 121a of the first die 121 and the molding surface 122a of the second die 122 in a very short time, and is then cooled and solidified as amorphous. glass. Thereby, a glass blank G is produced. The size of the glass blank G formed in the present embodiment depends on the size of the intended protective glass, but is, for example, about 20 to 200 mm in diameter (or a length of one side).

Further, in the press molding method of the present embodiment, the glass blank G is formed in the form of transferring the molding surface 121a of the first mold 121 and the molding surface 122a of the second mold 122, and therefore, molding of a pair of molds is performed. The flatness and smoothness of the surface are preferably equal to the flatness and smoothness of the intended cover glass. At this time, after the press molding, the surface processing step of the glass blank G is not required, that is, the cutting or grinding step is not required. That is, the glass blank G formed in the press molding method of the present embodiment may have the same thickness as the target thickness of the finally obtained protective glass. For example, the glass blank G is a circular plate having a thickness of 0.2 to 1.1 mm. The surface roughness of the molded surface 121a and the molded surface 122a is adjusted such that the arithmetic mean roughness Ra of the glass blank G is 0.001 to 0.1 μm, preferably 0.0005 to 0.05 μm.

After the first die 121 and the second die 122 are closed, the molding unit 120 is quickly moved to the exit position, and instead, the other molding unit 130 is moved to the trapping position, and the molding unit 130 is used to mold the paste ball G _G . .

After the press unit 120 has moved to the exit position, the first mold 121 and the second mold 122 are kept closed until the glass blank G is sufficiently cooled (at least at a temperature lower than the deformation point). Then, the first driving unit 123 and the second driving unit 124 are driven to separate the first mold 121 and the second mold 122, and the glass blank G is dropped from the molding unit 120 and is received by the first conveyor belt 171 located at the lower portion. (Refer to Figure 3).

In the apparatus 101, as described above, the first mold 121 and the second mold 122 are closed in a very short time of 0.1 second (about 0.06 seconds), and the molten glass is brought into contact with the molding surface 121a of the first mold 121 at substantially the same time. The entire molded surface 122a of the 2 mold 122. Therefore, the molding surface 121a of the first mold 121 and the molding surface 122a of the second mold 122 are not locally heated, and strain is hardly generated on the molding surface 121a and the molding surface 122a. Further, before the heat is moved from the molten glass to the first mold 121 and the second mold 122, since the molten glass is rolled, the temperature of the formed molten glass is substantially uniform. Therefore, when the molten glass is cooled, the distribution of the shrinkage amount of the glass material is small, and the strain of the large glass blank G does not occur. Therefore, the flatness of the main surface of the produced glass blank G is further improved as compared with the conventional glass blank produced by the press molding of the upper and lower molds.

In the example shown in Fig. 4, the cutting edges 161 and 162 are used to cut the molten glass L _G flowing out to form a substantially spherical paste ball G _G . However, when the viscosity of the molten glass material L _G is small relative to the volume of the paste ball G _G to be cut, only the glass to be cut L _G is cut, and the cut glass does not become substantially spherical. It is impossible to make a paste ball. At this time, a paste ball for making a paste ball is used to form a mold.

Fig. 5 (a) to (c) are diagrams for explaining a modification of the embodiment shown in Fig. 4. In this modification, a paste ball is used to form a mold. Of FIG. 5 (a) showing a state before the production of the paste balls, Fig. 5 (b) cutting the display unit 160 by the ball and the paste member 180 is formed to make the state of FIG paste ball G _G of FIG. 5 ( c) A diagram showing a state in which the glass blank G is produced by press molding the paste ball G _G .

As shown in Fig. 5(a), the molding unit 120 is further provided with components 181 and 182. The components 181, 182 are arranged in such a way as to be displaceable in the direction of proximity and departure. Further, the modules 181 and 182 are driven to open and close by a path of the common molten glass L _G by a driving means (not shown). The path of the molten glass L _G is closed by closing the components 181, 182 in the path of the molten glass L _G . Further, the block of the molten glass L _G cut by the cutting unit 160 is received by the recess 180C formed by the modules 181 and 182. Then, as shown in Fig. 5(b), by opening the modules 181 and 182, the molten glass L _G which is spherical in the concave portion 180C is dropped toward the molding unit 120 once, and the molten glass L _{G is} made into a spherical paste. Ball G _G . The spherical paste ball G _G is sandwiched between the first die 121 and the second die 122 and molded by the first die 121 and the second die 122 as shown in Fig. 5(c), thereby producing a circular glass blank. G.

Alternatively, as shown in Fig. 6 (a) to (d), the apparatus 101 does not use the cutting unit 160 shown in Figs. 5(a) to (c), but uses the paste ball forming mold 180 along the molten glass. A moving mechanism in which the path of L _G moves in the upstream side direction or the downstream side direction. Fig. 6 (a) to (d) are views for explaining a modification of the use of the paste ball forming mold 180. Fig. 6 (a) and (b) are views showing a state before the paste ball G _{G is} produced, and Fig. 6 (c) is a view showing a state in which the paste ball G _{G is} formed by the paste ball forming die 180, Fig. 6 (d) A diagram showing a state in which the glass blank G is produced by press molding the paste ball G _G .

As shown in Fig. 6(a), the concave portion 180C formed by the members 181 and 182 receives the molten glass L _G flowing out from the molten glass outflow port 111. Then, as shown in Fig. 6(b), in the timer, the components 181, 182 are quickly moved to the downstream side of the flow of the molten glass L _G . Thereby, the molten glass L _G is cut to form the paste ball G _G . Next, in the timer, as shown in Fig. 6(c), the components 181, 182 are moved away. Thereby, the molten paste ball G _G held by the components 181, 182 is dropped once. The paste ball G _{G is} spherical due to the surface tension of the molten glass L _G . The spherical paste ball G _G is sandwiched between the first die 121 and the second die 122 and molded by the first die 121 and the second die 122 as shown in Fig. 6(d), thereby producing a circular glass blank. G.

Fig. 7 (a) to (c) show that the block CP of the optical glass heated by the softening furnace not shown in the figure is dropped to replace the paste ball G _G , and is passed by the die 221, 222 on the way of the drop. A diagram of a modification in which both sides are sandwiched and subjected to press molding. Fig. 7(a) is a view showing a state before the block of the heated optical glass is formed, and Fig. 7(b) is a view showing a state in which the block of the optical glass is dropped, and Fig. 7(c) shows A diagram in which the bulk of the optical glass is molded to form a state of the glass blank G.

As shown in Figure 7 (a), the device 201 is held by a glass material. The device 212 transports the block CP of optical glass to the upper position of the molding unit 220. Then, in this position, as shown in Fig. 7(b), the device 201 opens the grip of the block CP of the optical glass by the glass material holding device 212, and the block CP of the optical glass is dropped. In the middle of the falling of the block CP of the optical glass, as shown in Fig. 7(c), the first mold 221 and the second mold 222 are sandwiched to form a circular glass blank G. Since the first die 221 and the second die 222 have the same configurations and operations as those of the first die 121 and the second die 122 shown in FIG. 5, the description thereof will be omitted.

<Modification for controlling the position of the cut mark>

In the press molding of the apparatus 101 described in detail above, the cutting of the paste ball G _G by the pair of cutting edges 161 and 162 may cause the glass blank G to be cut off. mark. If the cut marks remain on the protective glass for the portable machine, there is a problem in quality, so the cut marks must be removed in the subsequent steps. However, the position of the cut marks on the glass blank G varies depending on each glass blank, and in the subsequent shape processing step, the glass substrate of a desired shape cannot be stably cut out, and the yield is lowered. Doubt. Thus, when a pair of cutting blades 161 and 162 during cutting paste ball _G G, the preferred embodiment system to mark the cutting glass blanks forming the periphery of the ball is located to cut the paste _G G. According to the results of the study by the present inventors, it can be seen that the cutting edge 161 located above the pair of cutting edges 161 and 162 is formed thicker than the cutting edge 162 located below, and the paste ball G can be formed. The cut mark generated on _G is continuously positioned above in the drop, and even in the molding, the position of the cut mark on the paste ball G _G does not change, and as a result, the cut mark is generated on the periphery of the glass blank G (molding) The top of the middle). At this time, for example, the thickness of the upper cutting edge 161 is set to 1.5 mm, and the thickness of the lower cutting edge 162 is set to 1.0 mm.

<Modification 1 for removing the cut marks>

Further, it is also possible to adopt a configuration in which the cutting marks themselves are not generated on the glass blank G, instead of controlling the position of the cutting marks on the glass blank G. Hereinafter, a configuration example for removing the cut marks from the glass blank G will be described with reference to Fig. 8. Fig. 8 is a view similar to Fig. 4 in the same form. Fig. 8(a) shows a side view of the molten glass material L _G before it comes into contact with the cutting unit 160. Fig. 8(b) is a side view showing the cutting unit 160 cutting out the molten glass material L _G . Figure 8 (c) shows the press unit block 120 of the molten glass G _G side view of the molding. Fig. 8(d) is a side view showing a state in which the molten or softened glass protruding from the molding unit is removed.

As shown in Fig. 8, the apparatus of the present modification further includes a cutting blade 165, and the configuration other than the cutting blade 165 is the same as that shown in Fig. 3. The cutting edge 165 of the present modification is a blade that can be driven forward and backward in the horizontal direction at the upper end of the first die 121 and the second die 122, and is used to melt or soften in a state of being protruded from the molding unit 120. The glass is cut and set.

Fig. 8 (a) and (b) are the same as Fig. 4 (a) and (b), respectively. In the present modification, the first driving unit 123 and the second driving unit 124 drive the first mold 121 and the second mold at the timing when at least one of the cutting marks _G is protruded during the molding. 122. As a result, as shown in Fig. 8(c), the portion of the paste ball G _G that does not contain the cut mark T is trapped (trapped) between the first die 121 and the second die 122, and is cut off. The state in which the mark T protrudes from the molding unit 120. Next, as shown in Fig. 8(d), the cutting blade 165 removes the molten or softened glass which protrudes from the molding unit 120. The shape and material of the cutting blade 165 are not limited as long as the glass protruding from the molding unit 120 can be removed.

<Modification 2 for removing the cut marks>

Next, referring to Fig. 9 and Fig. 10, another configuration example for preventing the glass blank G from generating the cut marks itself will be described. Fig. 9(a) is a plan view showing the first die 321 and the second die 322 provided in the press unit 320 of the present modification. Fig. 9(b) is a side view showing the molding unit 320 of the present embodiment.

As shown in Fig. 9(a), the first die 321 and the second die 322 of the present embodiment have a shape in which a part of a substantially circular arc is cut into a linear shape. The first die 321 and the second die 322 are formed such that a straight portion L in which a part of the arc is cut into a straight line is vertically above. As shown in Fig. 9(b), the first die 321 and the second die 322 are opposed to each other in a state in which the normal direction of the surface for molding the paste ball in the open state is inclined with respect to the horizontal direction. To configure it. In addition, in the closed state, the interval between the pressing surface 321a of the first die 321 and the molding surface 322a of the second die 322 is kept constant, and a plate-shaped space is formed in the press unit 320, and the first die 321 is formed. Molded surface 321a and The molding surface 322a of the 2 mold 322 is provided with a projection 321b and a projection 322b, respectively.

Next, the press molding step of this modification will be described with reference to a side view shown in Fig. 10. Fig. 10 is a view similar to Fig. 4 in the same form. That is, Fig. 10(a) shows a plan view of the molten glass material L _G before it comes into contact with the molding unit 320. Fig. 10(b) is a side view showing the molding unit 320 cutting out the molten glass material L _G . Figure 10 (c) shows the press unit block 320 of the molten glass G _G side view of the molding.

As shown in Fig. 10(a), the molten glass material L _G continuously flows out from the molten glass outflow port 111. At this time, the first die 321 and the second die 322 move in the horizontal direction as indicated by arrows in Fig. 10(a). Then, the straight portion L disposed at the upper portion of the first die 321 and the linear portion L disposed at the upper portion of the second die 322 are in contact with each other, whereby the molten glass material L _{G is} cut as shown in Fig. 10(b). . Further, by cutting the molten glass material to form a paste balls L _{G G} G. At this time, the cut marks T are located in the vicinity of the respective straight portions L.

When the first mold 321 and the second mold 322 are in contact with each of the straight portions L, the first mold 321 and the second mold 322 are closed by a mold as shown by an arrow in FIG. 10(b). Each lower end moves. As a result, as shown in FIG. 10(c), the paste ball G _G is captured (trapped) between the first die 321 and the second die 322 to produce a glass blank G. In this method, the paste ball G _G is press-molded at the timing when the cut marks T of the paste balls G _G formed by the contact of the respective straight portions L are located in the vicinity of the respective straight portions L. Therefore, the cut marks are not generated in the glass blank G.

(b) Shape processing steps

Next, the shape processing step (step S20) will be described.

In the method for producing a glass blank according to the present embodiment, since the glass blank produced by the press molding step of the previous step has extremely high flatness and smoothness, it is not necessary to reheat the glass blank. The annealing step of removing the strain generated in the glass blank is performed, and the glass blank produced in the press molding step can be processed into the shape of the desired protective glass for the portable machine by the shape processing step.

That is, the shape processing step of processing the glass blank into the shape of the cover glass for the portable machine can be performed in a state in which the strain generated in the glass blank remains. Here, the strain at the surface portion of the glass blank is a compressive stress layer. When the block of molten glass is molded by a pair of dies, heat is transferred from the molten glass to the mold, and the surface side of the molten glass is cooled and solidified more than the center side, so that the center side of the molten glass is slower than the surface side. The film is cooled and solidified to form a shrinkage difference, and a compressive stress layer (that is, a compressive stress layer formed by physical strengthening) is formed by the difference in shrinkage.

The shape processing step is a step of obtaining a glass substrate by processing the glass blank obtained in the press molding step into a desired shape in accordance with the outer shape of the glass substrate for the portable device. A cutting method for processing a glass blank into a desired shape, such as etching, scribing, or the like.

In the cutting method according to the scribe line cutting, in order to process the glass blank into a desired shape, it is set and desired on the surface of the glass blank by a scriber made of a super steel alloy or diamond particles. Shape outline Consistent cut line (linear cut). The glass blank is then partially heated, and the cut line is grown by thermal expansion thereby removing only the desired area in the glass blank.

In the shape processing step to which the cutting method by etching is applied, the following (b-1) etching resistant film forming step, (b-2) pattern forming step, and (b-3) cutting step are included. step. The following describes a shape processing step using a cutting method in accordance with etching.

(b-1) Anti-etching film forming step

In the etching resistant film forming step, an etching resistant film is formed on at least one surface of the glass blank. The etching resistant film is usually formed on both sides of the glass blank, but in the subsequent cutting step, when only one side is brought into contact with the etching solution, it is only necessary to form an etching resistant film on the single surface. In the following description, the etching resistant film is formed on both sides of the glass blank as a premise. The etching resistant film may be partially removed in the subsequent pattern forming step as long as it can be partially removed by the pattern forming process, and is not dissolved or removed with respect to the etching solution used in the cutting step. Can be selected as appropriate. As the etching resistant film, a resist film which exhibits poor solubility or insolubility with respect to a hydrofluoric acid aqueous solution is preferably used. At this time, in the pattern forming step, the resist film is subjected to pattern formation processing by exposure processing using a photomask and development processing in accordance with the developer, and an etching solution is applied in the cutting step. Cut off.

(b-2) Pattern forming step

In the pattern forming step, at least the etching resistant film is patterned. Thereby, in the etching resistant film covering the entire surface of the glass blank, the etching resistant film other than the area corresponding to the planar direction of the glass substrate finally produced can be removed. A pattern forming method of the etching resistant film is representative, and a lithography technique in which the above exposure and development are combined can be applied. The pattern forming step may be performed on at least one side of the glass blank on which the etching resistant film is formed on both sides, or may be performed on both sides.

(b-3) cutting step

In the cutting step, the glass blank is cut into small pieces by etching the surface of the glass blank provided with the etching resistant film after the pattern formation is brought into contact with the etching solution. The etching treatment is usually carried out by immersing the glass blank in an etching solution. The etching solution is not particularly limited as long as it contains at least hydrofluoric acid, and other acids such as hydrochloric acid or various additives such as a surfactant may be added as necessary.

(c) Chemical strengthening steps

Next, the chemical strengthening step (step S30) will be described.

In the chemical strengthening step, a plurality of glass substrates processed into a desired shape by a shape processing step are loaded on a cassette (a holder), and the cassette is immersed in a chemical strengthening treatment liquid containing a molten salt. Thereby, one or more kinds of alkali metals contained in the glass substrate are subjected to ion exchange treatment with the alkali metal of the molten salt to form a compressive stress layer on the surface layer portion of the glass substrate.

The composition, temperature, and immersion time of the molten salt can be appropriately selected depending on the glass composition of the glass substrate, the thickness of the compressive stress layer formed on the surface layer portion of the glass substrate, and the like, and the glass composition of the glass substrate is the aluminosilicate described above. In the case of soda-lime glass, a low-temperature ion exchange method in which the treatment temperature of the chemical strengthening treatment liquid is usually set to 500 ° C or lower is preferably applied. In the high-temperature ion exchange method in which ion exchange is performed in a temperature region above the slow cooling point of the glass, a large strength such as a low-temperature ion exchange method cannot be obtained, and in addition, the glass surface is melted in the strengthening treatment. Since it is eroded and it is easy to damage transparency, it is difficult to obtain a glass substrate suitable for a protective glass for portable devices. For example, in the chemical strengthening step of the present embodiment, the composition, temperature, and immersion time of the molten salt are preferably selected from the ranges exemplified below.

. Composition of molten salt: potassium nitrate or a mixed salt of potassium nitrate and sodium nitrate

. Molten salt temperature: 320 ° C ~ 470 ° C

. Immersion time: 3 minutes to 600 minutes

(d) Decorative layer forming step

Next, a decorative layer forming step for forming the decorative layer 20 on the main surface of one of the chemically strengthened glass substrates 10 is performed (step S40). In the decorative layer forming step, the decorative layer 20 can be formed on the main surface of the glass substrate 10 by various printing methods generally known as screen printing or the like, or a generally known film forming method. A film forming method generally known, for example, a liquid phase film forming method generally known by a dipping method, a spray coating method, a sol-gel coating method, a plating method, or the like, or a vacuum evaporation method or a sputtering method can be applied. , A gas phase film formation method generally known by CVD (Chemical Vapor Deposition) or the like.

As described above, the method for producing a cover glass for a portable device according to the present embodiment includes a press molding step of molding a block of molten glass by a pair of dies. From this content, it can be known that if the surface roughness of the molding surface of a pair of dies is set to a good level in advance (for example, the surface roughness required for a cover glass for a portable machine), the surface roughness can be reversed. The surface roughness of the glass blank obtained by compression molding was printed. Therefore, the surface roughness of the glass blank can be formed to a good level.

In addition, in the press molding step, the relationship between the temperature difference between the mold at the opposite position and the flatness of the glass blank obtained after the press molding can be determined according to the relationship between the temperature difference between the molten glass and the flatness of the glass blank obtained after the press molding. The temperature difference between the one of the flatness required for the protective glass for the portable device and the mold is controlled so that the temperature of the pair of the molds can be within the temperature difference obtained as described above while controlling the temperature of the pair of molds. Perform molding. Therefore, by the glass blank obtained by the press molding step of the present embodiment, the surface roughness and flatness of the main surface can be made to the level required for the protective glass for portable machines. Therefore, the processing steps of the main surface are not required in the subsequent steps. In other words, the outer peripheral shape of the glass blank is processed to be portable by maintaining the surface state of the main surface of the glass blank and making the main surface of the glass blank the main surface of the protective glass for the portable machine. The shape processing step of the outer peripheral shape of the protective glass for the machine.

Although a glass base processed into a predetermined shape according to the glass blank The plate is chemically strengthened, but in the present embodiment, the flatness of the glass substrate is not deteriorated. Therefore, the resulting protective glass for portable machines is thin and has high mechanical strength, and the flatness is higher than ever.

Further, in the method for producing a cover glass for a portable device according to the present embodiment, the size of the glass blank produced in the press molding step is close to the size of the cover glass for the portable device, and the glass wool can be used according to the glass wool. The embryo is processed into a desired shape, so it is suitable for a small number of multi-item production.

(2) Second embodiment

Next, a method of manufacturing the cover glass for a portable device according to the second embodiment will be described.

In the past, the protective glass for portable devices was mainly used to protect the display screen, and the overall shape was almost flat. On the other hand, in order to protect the frame of the portable machine, stainless steel has been used in the past, but such a portable machine may cause damage in the frame portion of the stainless steel due to the use condition, and the use may be Reduce the aesthetics of portable machines. Therefore, in addition to the protection of the display screen of the portable device, the use of a thin tempered glass is increasingly required for the purpose of protecting the frame of the portable device.

The shape of the casing of the portable machine is generally three-dimensional, but it is difficult to produce a three-dimensional portable protective glass for a machine according to the plate glass obtained by the floating molding method or the down-draw method. That is, in order to manufacture a three-dimensional portable protective glass for a machine according to the sheet glass obtained by the floating forming method or the down-draw method, if the sheet glass is not remelted and melted The molten glass flows into a mold that can obtain a desired three-dimensional shape, and is difficult to produce. On the other hand, in the press molding method described in the first embodiment, a mold conforming to the outer shape of the desired protective glass for a portable machine is prepared without re-melting, and high flatness can be obtained. Smoothness is therefore suitable for the production of protective glass for portable machines for the protection of the frame of a portable machine.

For example, Fig. 11 shows an example of the appearance of a protective glass for a portable machine having a three-dimensional shape. The protective glass for a portable device illustrated in Fig. 11 has a substantially sinuous shape and is in the form of a casing covering the portable device from the inside.

Fig. 12 is a view specifically showing a press molding method for producing a glass blank for a cover glass for a portable machine exemplified in Fig. 11. Fig. 12(a) is a view showing a state before the preparation of the paste ball, Fig. 12(b) is a view showing a state in which the paste ball is made by the cutting unit 160, and Fig. 12(c) is shown by the paste ball. A state in which the glass blank G is molded by molding.

In the press molding method, first, as shown in Fig. 12(a), the molten glass material L _G continuously flows out from the molten glass outflow port 111. At this time, the cutting unit 160 is driven at a predetermined timing, and the molten glass material L _G is cut by the cutting edges 161 and 162 (Fig. 12(b)). The above contents are the same as those of the press molding method described in the first embodiment.

In the press unit 420 of the present embodiment, the first mold 421 and the second mold 422 having a shape corresponding to the closed space of the glass blank G of the target three-dimensional shape are obtained when the mold is closed. For example, in the production of Figure 11 In the case of the glass blank G of the shape shown in the figure, it is configured to obtain a closed space which is the same as the shape shown in Fig. 11 when the mold is closed. In other words, in the present embodiment, the first mold 421 has a structure (convex structure) that protrudes in the molding direction, and the second mold 422 has a structure (concave structure) that is recessed in the molding direction. The shape of the mold can be appropriately changed in accordance with the design of the protective glass, and by changing the shape of the mold, the glass blank can be partially bent in the thickness direction to increase the degree of freedom of the shape of the protective glass.

In the press molding method of the present embodiment, the paste ball G _G produced in the same manner as in the first embodiment is dropped toward the gap between the first die 421 and the second die 422 of the press unit 420. At this time, when the paste ball G _G enters the gap between the first die 421 and the second die 422, the first die 421 and the second die 422 are driven to approach each other to make the paste ball G _G It is captured (captured) by the first die 421 and the second die 422. At this time, as shown in Fig. 12(c), the outer circumferential surface 421b of the molding surface 421a of the first die 421 abuts against the outer circumferential surface 422b of the molding surface 422a of the second die 422. Further, the paste ball G _G sandwiched between the press surface 421a of the first die 421 and the press surface 422a of the second die 422 is rapidly cooled and solidified, and is formed into the same shape as that shown in FIG. Glass blank G.

In the press molding method of the present embodiment, the surface roughness of the press surface 421a and the press surface 422a is such that the arithmetic mean roughness Ra of the glass blank G is 0.001 μm to 0.1 μm, preferably 0.0005 μm to 0.05 μm. By adjusting the method, the smoothness of the surface of the glass blank G can be extremely high, and the cutting and polishing steps after the main surface is not required to be molded can be performed. That is, the protective glass for a portable machine according to the embodiment The manufacturing method can produce a glass blank having almost the same shape as the protective glass of the three-dimensional shape of the final product (that is, a non-flat desired shape) by the above-mentioned press molding method, and is suitable for manufacturing a portable machine. Protective glass for portable machines for the purpose of protection of the frame.

In the method for producing a cover glass for a portable device according to the present embodiment, the chemical strengthening step and the decorative layer forming step described in the first embodiment may be included.

Further, the required values vary depending on the model or size used, but in general, the flatness required for the protective glass for a portable device is preferably 20 μm or less at a length of about 8 cm. The above-described requirements can be satisfied by the method for producing a protective glass blank for a portable machine according to the present embodiment.

[Examples]

The following series are given by way of examples of the invention, but the invention is not limited to the following examples.

[Examples]

First, a molten glass material containing 63.5% by weight of SiO ₂ , 8.2% by weight of Al ₂ O ₃ , 8.0% by weight of Li ₂ O, 10.4% by weight of Na ₂ O, and 11.9% by weight of ZrO ₂ was prepared and used. In the press molding method according to the first embodiment of the present invention (the method using the apparatus of Figs. 3 and 4), a glass blank having a diameter of 90 mm and a thickness of 0.7 mm was produced. The temperature of the molten glass material L _G discharged from the molten glass outflow port 111 was 1300 ° C, and the viscosity of the molten glass material L _G at this time was 700 poise. Further, the surface roughness (arithmetic mean roughness Ra) of the molding surfaces of the first mold and the second mold is 0.01 μm to 1 μm.

The molten glass material L _G discharged from the molten glass outflow port 111 is cut by the cutting unit 160 to form a paste ball G _G having a diameter of about 20 mm. The paste ball G _G is molded by a molding unit at a load of 3000 kgf until the temperature becomes below the glass transition point (Tg) of the molten glass material (about 3 seconds) to form a glass blank having a diameter of 90 mm. The glass blank was cut into small pieces of 45 mm × 80 mm.

In the embodiment, when the flatness required for the cover glass for a portable device is 8 μm or less, in order to achieve the flatness, the temperature difference between the first mold and the second mold is set to 10 in each of the press units. Within °C. Specifically, the temperature difference of the first mold was 420 ° C, and the temperature difference of the second mold was 411 to 429 ° C.

Next, the glass blank was immersed in the molten salt to apply chemical strengthening, and a compressive stress layer of about 40 μm was formed on both sides of the glass blank. The molten salt in the chemical strengthening (ion exchange treatment) is a mixed salt of potassium nitrate and sodium nitrate (mixing ratio is potassium nitrate: sodium nitrate = 60:40 in terms of % by weight), so that the thickness of the compressive stress layer becomes In the above-described thickness, the immersion time is appropriately adjusted while maintaining the temperature of the molten salt in the range of 320 ° C to 360 ° C.

[Measurement of Glass Embryo of Example]

45mm × 80mm glass blanks made in the examples The glass wool embryo after chemical strengthening was measured for flatness and surface roughness (arithmetic mean roughness Ra).

The flatness is measured by JIS B0602, for example, using a Flatness Tester FT-900 manufactured by Nidek. The evaluation criteria of the flatness shown in Table 1 are as follows.

◎: Ra is 4.0 μm or less

○: Ra is more than 4.0 μm and is 8.0 μm or less

△: Ra is more than 8.0 μm and is 12.0 μm or less.

×: Ra is greater than 12.0 μm

The surface roughness is expressed by the arithmetic mean roughness Ra defined by JIS B0601:2001 (or ISO 4287:1997), and when it is 0.006 μm or more and 200 μm or less, for example, a roughness tester SV- manufactured by Mitsutoyo Co., Ltd. It was measured by 3100 and calculated by the method prescribed by JIS B0633:2001 (or ISO 4288:1996). As a result, when the roughness is 0.03 μm or less, it can be measured, for example, by a scanning probe microscope (atomic force microscope; AFM) nanosecond oscilloscope manufactured by Veeco, Japan, and is regulated by JIS R1683:2007. Method to calculate. In the present application, the arithmetic mean roughness Ra when measured in a measurement range of 1 μm × 1 μm square with a resolution of 512 × 512 pixels is used.

The evaluation criteria of the surface roughness shown in Table 1 are as follows.

○: Ra is 0.01 μm or less

△: Ra is larger than 0.01 μm and is 0.1 μm or less

×: Ra is greater than 0.1 μm

From the first table, it is understood that there is a correlation between the temperature difference between the molds and the flatness of the glass blanks in each of the glass blanks of each of the examples. Especially at a temperature difference of 0 ° C, the highest flatness can be obtained. Further, the shape of the molding surface of the first mold and the second mold is transferred to the glass blank, and the surface roughness of the molded surface of the first mold and the second mold is almost the same for the surface roughness of the glass blank of each of the examples. .

In the above, the embodiment of the present invention is described in detail. However, the method for producing a cover glass blank for an electronic device and the method for producing the cover glass for an electronic device of the present invention are not limited to the above embodiments, and the present invention is not deviated from the gist of the present invention. Of course, various improvements or changes can be made within the scope.

In addition, in addition to the protective glass blank for an electronic device manufactured by the method of the present invention, the protective glass blank for the portable device can be used for protecting the internal substrate of the touch sensor. Protective glass for use as a touch sensor for a substrate for a protective glass for a touch sensor Glass hair embryo.

10‧‧‧ glass substrate

10T, 10B‧‧‧ main surface

10U, 10V‧‧‧ compressive stress layer

20‧‧‧Printing layer

Fig. 1 is a view showing the configuration of a cover glass for a portable device according to an embodiment.

Fig. 2 is a view showing the flow of an embodiment of a method for producing a cover glass for a portable device according to an embodiment.

Fig. 3 is a plan view showing the apparatus used in the press molding of the embodiment.

Fig. 4 is a view showing the arrangement of the molding units of the apparatus 4 used in the press molding of the embodiment.

Fig. 5 is a view showing a modification of press molding using an embodiment of a paste ball molding die.

Fig. 6 is a view showing a modification of the press molding of the embodiment in which the cutting unit is not used.

Fig. 7 is a view showing a modification of press molding using an embodiment of an optical glass heated by a softening furnace.

Fig. 8 is a view showing a configuration example for removing a cut mark from a glass blank.

Fig. 9 is a view showing a configuration example for preventing the glass blank from being cut.

Fig. 10 is a view showing a modification of the press molding for causing the glass blank to not cause the cut marks.

Figure 11 is a three-dimensional shape of a protective glass for a portable machine. An example of an appearance shape.

Fig. 12 is a view showing, in particular, a press molding method for producing a glass blank for a cover glass for a portable machine exemplified in Fig. 11.

111‧‧‧ molten glass outflow

120‧‧‧Molding unit

121‧‧‧1st model

121a, 122a‧‧‧ molded surface

121b, 122b‧‧‧ prominence

122‧‧‧2nd mode

160‧‧‧cutting unit

161, 162‧‧ cut blades

G‧‧‧glass blank

G _G ‧‧‧ cream ball

L _G ‧‧‧ molten glass

Claims (9)

A method for producing a protective glass blank for an electronic device, comprising: a method for producing a protective glass blank for an electronic device in which a block of a molten glass is molded by a pair of molds, wherein the melting is performed according to the melting method In the case of glass molding, the temperature difference between the mold at the opposite position and the flatness of the glass blank obtained after press molding are used to obtain the flatness required for the protective glass for electronic equipment. The temperature difference between the pair of dies is subjected to press molding while controlling the temperature of the pair of dies so that the temperature of the pair of dies can be within the above-described temperature difference. The method for producing a cover glass blank for an electronic device according to claim 1, wherein in the press molding step, a temperature at a portion where the pair of the molds are in contact with each of the molten glass is in the pair of molds Molding is performed in such a manner as to become the same temperature. The method for producing a cover glass blank for an electronic device according to claim 1 or 2, wherein a temperature of the pair of dies from the block to the mold to be separated is set to be less than the melting The temperature of the glass transition point (Tg) of the glass. The method for producing a cover glass blank for an electronic device according to any one of claims 1 to 3, wherein the thickness of the glass blank obtained by the press molding step is used for the electronic device. Molding is performed in such a manner that the thickness of the protective glass is the same as the thickness of the sheet. An electronic product as claimed in any one of claims 1 to 4 A method for producing a protective glass blank for a machine, comprising: a cutting step of cutting the molten glass to cause the block to fall toward the pair of molds, wherein in the cutting step, the cut mark of the molten glass is located The periphery of the glass blank is used to cut the molten glass. The method for producing a cover glass blank for an electronic device according to any one of claims 1 to 4, further comprising: a cutting step of cutting the molten glass to cause the block to fall toward the pair of dies; In the above-described press molding step, the molten glass is molded at a timing at which the cut marks of the molten glass protrude from the pair of the molds. A glass blank for manufacturing a protective glass blank for an electronic device according to any one of claims 1 to 6, wherein the glass blank is produced by the method for producing a protective glass blank for an electronic device according to any one of claims 1 to 6. In the state in which the strain generated is left, the shape processing step of processing the glass blank into a shape of a cover glass for an electronic device is performed. A method for producing a cover glass for an electronic device, which is characterized in that the glass blank produced by the method for producing a protective glass blank for an electronic device according to any one of claims 1 to 6 The surface state of the main surface is such that the outer surface of the glass blank is processed into the outer peripheral shape of the protective glass for electronic equipment so that the main surface of the glass blank is the main surface of the protective glass for electronic equipment. step. A method for manufacturing a cover glass for an electronic machine, characterized in that The use of a glass blank for an electronic device obtained by the method for producing a protective glass blank for an electronic device according to any one of the first to sixth aspects of the invention is to produce a cover glass for an electronic device.