KR101093914B1 - Method for fabricating glass panels - Google Patents

Abstract

The method of forming glass with substantially reduced inclusions and cords comprises reducing the shear rate while at the same time achieving a predetermined stirring efficiency in the stirring operation by appropriately selecting the stirring diameter, stirring speed and bonding distance. The stirring device 100 includes a stirring vessel 101 that receives a flowable glass 105 at the inlet 107. The glass is then stirred by the rotation of the shaft with the stirrer 103 to enhance the uniformity of the glass material 106 carried to the outlet 108. The bonding distance is the distance between the stirrer blades and the inner wall 102 of the stirring vessel. The glass can be used to make glass sheets for flat panel displays, such as liquid crystal displays, personal digital assistants, and cellular phones used in computer monitors. The glass sheet may have a thin film transistor component for use in forming pixels on a display.

Stirrer Diameter, Stirring Speed, Stirring Efficiency, Shear Rate, Inclusions, Cords, Glass

Description

Method for manufacturing glass panel {Method for fabricating glass panels}

Display devices are used in various fields. For example, glass substrates are used in notebook computers, flat panel desktop monitors, LCD televisions, and Internet and communication device transistor active matrix liquid crystal displays (AMLCDs) and thin film transistor liquid crystal displays (TFT-LCDs), which are only a few. Do.

Many LCD-based display devices, certain electronic components, are often fabricated on the glass substrate of the display device. Generally, the transistor is a thin film transistor (TFT) and is a complementary metal oxide semiconductoe (CMOS) device. In this field, it is advantageous to form a semiconductor structure directly on the glass material of the display.

Thus, many LCD displays often include glass substrates having transistors formed above the glass substrate and below the LC material layer. The transistors are arranged in a patterned array and operated by peripheral circuitry which provides swithching for a given voltage to be directed to molecules of the LC material in a preferred manner. The transistor thus produces a pixel (pixel) of the display.

In most of these display devices, the demand for uniformity of glass materials has increased significantly. For this reason, the glass substrates used in such display devices are advantageous because they are free of inclusions and surface abnormalities when not needed. These requirements place certain requirements on the manufacturing process.

Four particular defect types can be advantageously mitigated to provide glass substrates useful for the display devices described above. For example, cords, erosion-source platinum, condensation-source content inclusions and precipitation-source content are usefully reduced or substantially eliminated.

The code is chemically inhomogeneous in the glass and is marked as a visible defect in the display glass due to the waveform on the surface of the glass sheet whose length of corrugation is parallel to the pulling direction. These waveforms on both the surface and the sheet cause an alternating longitudinal light and a lens effect that can produce dark bands in the space of a few millimeters when passing through the sheet. These waveforms also cause color or line patterns in the final display.

Erosion-source platinum inclusions are often generated by shear stresses imposed on the stir vessel walls and stirrer blades. Such small inclusions can cause small surface discontinuities on the glass surface. The small surface discontinuity has the potential to cause performance defects in terms of color filters of TFTs and displays. These combinations can have a tremendous impact on the filter side of a TFT cell because the color filter is manufactured in the entire surface process rather than the discrete area process as on the TFT side of the cell.

The condensation-source content is derived from the volatilization of precious metals or chemical constituents of the glass at the free surface at the top of the stirring chamber condensation, condensing on the cooler surface and then falling into the cast glass and causing solid or gas phase defects. Often occurs. Solid defects cause problems in the aforementioned products. The gas phase defects can disturb the surface, but more easily become optical defects in the pixels of the final product.

Precipitation-source platinum inclusions often occur downstream of the production system of stirred vessels where the glass flow is substantially thin. Platinum (Pt) or other elements from the manufacturing process diffuse into the glass flowing at the interface between the glass and the container. The amount of element (Pt or rhodium (Rh)) present in the glass is a function of the temperature and time that the glass is in close contact with the vessel, and the solubility and diffusivity of the element in the glass. The downstream precipitation of these elements depends on each other's concentration, thermodynamics and kinetics of elemental crystallization, and the time-temperature history recorded by the manufacturing process.

Accordingly, what is needed is a method and apparatus for manufacturing glass panels that address the above-mentioned minimal issues. For example, a reduction in shear stress is required to meet current and future platinum micro-content requirements for LCD display glass substrates.

summary

According to an embodiment embodiment, a method of making a glass with substantially reduced inclusions and cords is a shear stress while maintaining predetermined stirring efficiency in agitation operation by appropriately selecting the stirrer size, stirrer speed and bonding distance. Reducing the pressure.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be well understood from the detailed description which follows, taken in conjunction with the accompanying drawings. The various features need not necessarily be made to a particular size. Indeed, the size may be arbitrarily increased or decreased for clarity of discussion.

1 is a cross section of a stirring vessel and stirrer according to an embodiment embodiment.

2 is a table showing the conditions of constant stirring efficiency according to the embodiment embodiment.

3 is a graph of the stirring efficiency required as a function of speed according to the embodiment embodiment.

4 is a table showing the conditions of constant stirring efficiency according to the embodiment embodiment.

5 is a graphical representation of product loss over time according to example embodiments.

6 is a graphical representation of shear stress versus agitation efficiency according to an embodiment embodiment.

7 is the shear stress at the inner wall of the stirring vessel with respect to temperature in accordance with the embodiment embodiment.

8A and 8B are stained images of glass materials with enhanced mixing of glass and well known methods, poor mixing of glass by each, according to an embodiment embodiment.

9 is a graphical representation of intensity versus pixel distance in accordance with an embodiment embodiment.

10 is a graphical representation of agitation efficiency index versus shear rate distance in accordance with an embodiment embodiment.

In the detailed description that follows, example embodiments are provided that disclose specific details to provide a thorough understanding of the present invention, which is for illustrative purposes only and is not intended to be limiting. However, it will be apparent to one skilled in the art that the present invention may be practiced in other embodiments that are distinct from the specific details disclosed herein. Moreover, well-known devices, methods and materials may be omitted unless they obscure the description of the invention.

In sum, the embodiment embodiments described herein depict the stirring device (stirrer) shapes used in the manufacture of glass sheets for use in various display products. The shape of the stirrer is described in connection with the extension of this technique to reduce stirrer efficiency and shear stress at the platinum surface, and precipitation source content. Moreover, the embodiment specification reduces the code in the glass display caused by the distinct glass materials that vary the viscosity while at the same time reducing the aforementioned power agglomeration-induced inclusions. The latter is manifested by increasing the rate of output from the stirred vessel, which reduces the timing of this chemical non-uniformity-causal waveform in the final product. In an embodiment embodiment, the distance between the stirrer blades and the stir vessel wall (referred to as the coupling distance "C") is increased while the circular velocity of the stirrer is increased. This reduces the occurrence of platinum content as well as the cord in the product obtained.

1 shows a stirring device 100 according to an embodiment embodiment. The stirring device 100 includes a stirring vessel 101 for receiving a fluid glass 105 at an inlet 107. This glass is then stirred by the stirrer 103 to enhance the uniformity of the glass material 106 to be conveyed to the outlet 108. Thus, the glass material 105 flows in a downward direction and the radial movement of the stirrer 103 about its shaft is reduced if it does not substantially eliminate the nonuniformity of the glass material in the embodiment embodiment. Responsible.

As will be clearer by the description of the present invention, increasing the shear stress on the glass material 105 will reduce the non-uniform nature of the glass material 106. However, the greater the shear stress, the greater the tendency that materials from the stirrer 103 and the stirring vessel 101 must be forcibly removed from these elements and introduced into the glass material 106. Eventually, if this occurs, defects of the material will be expressed in surface non-uniformity and optical abberations in the glass panel. Thus, the embodiment specification refers to these phenomena in order to eliminate both codes and inclusions to an acceptable level for use in present and future glass applications where they should be minimized. According to the embodiment embodiments described herein, the best bonding distance is realized and the rotation rate of the stirrer 103 is subject to a desired stirring process to reduce both the non-uniformity of the glass material 106 and the desired release rate. This is so that the distance between any remaining non-uniform and separated portions of the glass material is substantially removed from the resulting glass sheet and the contents are also small enough to be substantially removed.

According to an exemplary embodiment, the Pt content having a diameter of approximately 50 μm or more is substantially removed. Naturally, the threshold size of the Pt content is advantageously reduced to less than 50 μm. The chord is measured by a gauge with an output of intensity contrast between the intensity bands of the chord. Under this type of measurement, the glass making method according to an exemplary embodiment may show a contrast measurement of less than about 0.67%.

As mentioned above, the generation | occurrence | production of the cord of the obtained glass sheet becomes a special problem. For this reason, the cord is at least from fire resistant erosion products and free volatile products. For example, non-uniform glass (eg, glass 105) entering the stirring system may have increased alumina concentration, or silica concentration, or both. It has been found from the physical model that when the agitation process receives a continuous inlet flow of non-uniform glass, it is clear that it produces an outlet stream containing distinct non-uniform elements even at significantly reduced concentration levels. The width and pitch of each of these distinct elements is inversely proportional to the stirring speed. For example, increased agitation rates can reduce non-uniformity through the resulting shear stress divided in the distinct glass.

Moreover, the visibility of surface waveforms is known to depend on amplitude and pitch. As described in more detail below, as the pitch between the waveforms decreases due to the faster velocity of the exit of the glass material from the stirring vessel 101 (eg, glass material 106), the optical effects of the waveforms decrease. It becomes difficult to observe (even if their area does not change) and the target agitation efficiency actually decreases. This is a reflection of the influence of the stirring speed on the clarity of the cord. This property increases the bond distance to achieve a further reduction in shear stress.

Quantitatively, the effectiveness of the agitation, E, can be approached as follows:

Where k is the proportional constant, B is the number of blades in the stirrer, D is the blade diameter, N is the stirring speed, τ is the shear stress, V is the volume of the stirring vessel, Q is the flow rate of the glass in the vessel, and μ is the Viscosity.

Equation (1) indicates that if E is maintained and τ decreases, D and V should increase. According to an embodiment embodiment, a larger stirring diameter and a larger stirring volume (ie, increased size of the stirring vessel 101) as a result of the decrease in viscosity reduces the shear stress for the platinum stirring portion (stirring vessel and stirrer) by about 80%. Thereby effectively reducing the formation of micro-Pt inclusions. According to the embodiment embodiment, the further reduction in shear stress is effected by investigating the effect of the bond "C" between the stirrer and the stirring vessel on the shear stress.

Shear stress can be expressed as follows:

Where v is the viscosity of the glass material and C is the bonding distance between the blade of the stirrer 103 and the inner wall 102 of the stirring vessel 101.

Substituting equation (2) into equation (1) gives:

Where k '= πk.

When E, B, V and Q remain constant, the effect of changing D, N and C can be measured from the following equation:

The goal is to find conditions under which the left part of equation (4) remains constant for minimal shear stress. The results of equation (4) using normalized numbers can be seen in the table of FIG.

The portion of the stirring vessel where the stirrer applies the greatest shear stress to the glass is the region closest to the blade of the stirrer 103 and the inner wall 102 of the stirring vessel. In other words, the shear rate (slope gradient of the fluid between the two surfaces) and the shear stress are maximum at the joining portion adjacent to the stir vessel wall. This portion is often referred to in the art as a binding portion. By increasing the distance between the edge of the blade of the stirrer 103 and the inner wall 102, the bonding distance "C", the volume of the very shear stressed glass is determined by the outer diameter of the shaft 104 and the tip of the blade ("blade portion"). Increases proportionally to the lower shear stressed volume between " In an embodiment embodiment, it is advantageous for the bonding distance in a stirring vessel having a 9.875 "diameter to be about 5/8" to about 7/8 ". Furthermore, for these two bonding distances according to the embodiment embodiment, for low shear stress volumes, The proportion of high shear stress volumes is 0.315 and 0.396, respectively. At bond distances greater than approximately 0.75 ", the stirring efficiency measured in the physical model is substantially reduced.

Equation 3, based on the physical model of the stirrer for many glass applications, states that the stirring efficiency (E) is directly proportional to the stirrer speed (N) and inversely to the square root (C) of the bonds. Experience with other glass agitation applications with LCD sheets indicates that the scale-up of the agitation process can be done successfully if the agitation efficiency (E) is the same in both cases. For example, Equation 3 would require a 40% increase in speed N to keep E equal when the bond distance C doubles.

However, FIG. 3 is a graphical representation of the stirrer efficiency required to make acceptable code quality in LCD sheet glass as a function of stirring speed and bonding. Curve 301 represents the stirring efficiency required to realize an acceptable cord in the glass sheet. For LCD glass, the agitation efficiency required is not the same for all cases that meet the code requirements. The required stirring efficiency actually decreases (for the same stirring vessel diameter) as the binding and speed increase. The measurements indicate that the spacing of the surface waveforms becomes smaller with increasing speed, making the code more difficult to see. Although it is expected that the speed required to achieve acceptable code will increase as the coupling increases, the speed required does not increase much as expected in Eq. Therefore, the shear stress applied to the stirrer and the stirring vessel platinum portion can be reduced as the bonding distance increases to a predetermined value C. According to the embodiment embodiment, if C is increased above a value in the range of about 0.75 "to about 1.0", which is exemplified above, the agitation becomes less effective and also allows for greater stirring efficiency and shear stress to meet the code requirements. You will be asked. As such, for each embodiment embodiment, there is an optimal bond where the shear stress on the platinum portion is minimized. According to an illustrative embodiment, this optimal combination is in the range of about 0.5 "to about 0.75" for making glass panels for LCD applications.

The curve 301 fitted through the three operating points above can be accessed by the power function:

From this experimental example, the left part of equation (4) is not constant unless the target E is a constant. Substituting Eq. (5) into Eq. (4) explains this and leads to the following equation:

From equation (6), the table of FIG. 2 was modified to give the table of FIG. From the table of FIG. 4, it is confirmed that by increasing the bond distance, an acceptable reduction of shear stress can be achieved while at the same time achieving acceptable code quality. As can be seen, the shear stress increases as the bond increases to meet the code requirements. According to an embodiment embodiment, there is a best fit with minimal shear stress on the platinum portion. In the embodiment embodiment, the optimum combination that yields the minimum shear stress for acceptable cord quality is in the range of about 0.3125 "to about 0.75" for the stir vessel and stirrer described herein.

As can be seen, the stated limit of coupling distances in the range of about 0.3125 "to about 0.75" is also a coupling distance beyond that not implied in Equations 5 and 6. For this reason, Equations 5 and 6 are based on the experience with actual stirrers with coupling distances. The physical model also suggests that the stirring performance begins to fall between C = 0.75 "and C = 1.25". It should also be noted that the bonding distance of 0.75 "is close to the optimum in the embodiment embodiment where the stirring vessel has a 9.875" diameter.

The purpose of reducing the shear stress at the platinum surface is to reduce the platinum erosion content in the drawn sheet glass, leading to rejection of the product. Indirect evidence that this object is achieved by increasing the coupling distance is shown in FIG. 5. For this reason, FIG. 5 shows the percent product loss seen for the glass from known processes, with each period being a production period. The first five data sets, periods 1 through 5, show product loss for glass made with a 9.25 "stirrer in a 9.875" stirrer vessel. The remaining three periods, periods 6 through 8, are embodiment embodiments using a stirrer with a 8.375 "diameter and a stirring vessel with a 9.875" internal diameter (C = 0.75 "). As readily determined, the finishing loss is approximately 40% reduction or further reduction in binding parameters described above in connection with embodiment embodiments.

It should be noted that the approximately 3/4 reduction in shear stress of the example embodiment is performed by lowering the viscosity to about 2/3 and expanding about 1/4 of the stirring system. Viscosity reduction can be effected by increasing the temperature of the glass material of the stirrer. In one embodiment embodiment, this results in a glass temperature of approximately 80 ° C .; That is, by increasing the glass viscosity to about 3000 poise (g · cm ⁻¹ · sec ⁻¹ ) from 1400 ° C. to a glass viscosity of about 1000 poise 1480 ° C. This is equivalent to a 2/3 reduced reference viscosity.

It should be noted that this substantial increase in temperature can reduce the strength of the precious metal portions of the stirring vessel and stirrer and increase the volatility of the platinum portion due to oxidation. Because of this, condensation of the platinum oxide at the continuous oxidation and cooling surfaces of the platinum alloy portion results in a source of platinum particles that can fall into the glass and cause defects. To reduce this phenomenon, a temperature decrease is necessary. In addition, a decrease in temperature in the stirring vessel will reduce the temperature of the glass entering the stirring vessel, which will reduce the chance of platinum dissolving into the glass from the stirring vessel and the stirrer. This will eventually reduce the potential for erosion of platinum defects from solution.

According to an illustrative embodiment, the temperature reduction can be achieved without increasing the shear stress by increasing the bond distance to lower the shear stress and then reducing the temperature to return the shear stress to the previous level. The effect of the bond on the shear stress is shown in the table of FIG. 4 and can be seen graphically in FIG. 6 showing the shear stress versus stirring efficiency according to the embodiment embodiment.

Curve 601 represents the relationship between shear stress and agitation efficiency in a known, relatively high viscosity stirrer. (All shear stresses shown in this diagram are shown at 1000 poise for comparison.) Line 602 connecting curve 601 with curve 603 is a line of constant bond, C. Operating lines for other agitators ranging in diameter from 5.25 "to 9.25" with a bond of 0.3125 "will fall into this line, which has the effect of increasing the agitator diameter for shear stress. Smaller (5.875" diameter) conditions Following this line from to a larger stirring system results in a shear stress reduction of about 0.38 psi to 0.27 psi at 1000 poise. This is a significant reduction in shear stress of about 30%.

Line 604 connecting line 603 and line 605 (C = .75 ") represents an operating line for the desired agitation efficiency as the coupling changes from approximately 0.3125" to approximately 0.75 ". This shows that in an exemplary embodiment, the shear stress can be further reduced by about 50% (up to about 0.14 psi) by increasing the bonding distance, based on the agitation efficiency (E) definition from Equation 1. Exemplary ranges of agitation efficiency to achieve acceptable and cord content are approximately 175 to approximately 250 over a bonding range of 0.3125 "to 0.75". For example, a 9.875 "ID stirring vessel, two different stirrer diameters , 9.25 "(0.3125" bond) and 0.875 "(0.75" bond) are performed in an exemplary embodiment. The stirring efficiency required for the 9.25 "diameter stirrer is approximately 250. The stirring efficiency required for the 8.375" diameter stirrer is approximately 175. For the same 1000 poise viscosity, the shear stress for the 9.25 "diameter stirrer was 0.270 psi. The shear stress for the smaller 8.375" diameter stirrer was 0.136 psi. Using these variables, the stirrer of the exemplary embodiment can lead to codes acceptable in many applications, including LCD displays.

It should also be noted that the benefits from increased bonds can also be used to reduce the temperature if a shear stress of 0.27 psi is acceptable for the platinum erosion content at lower system temperatures. 7 is a graphical representation of shear stress versus temperature for an interior wall of a stirring vessel. This graph shows the operating characteristics of the stirrer according to the embodiment embodiment (C = 0.75 "). The dots 701 in the graph show the proven operating conditions for the stirrer of the embodiment embodiment operating at 1480 ° C. and 16 RPM, in particular. Following a line of constant agitation efficiency (702; E180) for shear stress (703; 0.27 psi) in one stirrer, 1480 ° C. to about 1430 ° C. without increasing the shear stress successfully achieved with another stirrer. It may be desirable to reduce the temperature, which would be desirable if more inclusions emerge from the solution / precipitation reaction than from physical erosion, which also means that the erosion resistance of the platinum portion is more than the effect of increased shear stress on the platinum portion. It would be possible if the temperature increased faster at lower temperatures.

According to the embodiment embodiments, a series of oil modeling experiments were performed to determine the bond distance that delivered the optimum stirring efficiency as a function of the shear stress between the stirring blade and the stirring vessel wall. Agitators 5/16 _^"1/2". 9/16 ", 5/8", 11/16 ", _^3/4" and 7/8 "were performed in a standardized blade to produce a combined distance. The stirrer is typically 9 rpm to 25 rpm rotation speed of The range was tested, which yielded a range of shear rates between the blade and the inner wall of approximately 5s ^-1 to 20s ^-1 , approximately 15s ^-1 at 1000 poise viscosity for illustrative purposes. Shear rates in excess lead to unacceptable Pt erosion and inclusions in the resulting product.

Stirrer effectiveness was determined by analysis of the stirrer's ability to disperse partially and temporarily injected dye. A transparent plastic container geometrically close to the stirring vessel was used for the production. The glass was decorated with polyisobutylene oil at viscosity, density and flow rate which provided power similitude for producing glass in a hot stirring vessel. A relatively small volume of dyed oil (approximately 25 times the viscosity of clean matrix oil) was injected into the stir vessel, flowed through the rotating blades into the stir vessel and released from the vessel. The model involves the use of known equipment that includes square transparent pipes to facilitate normal observation and imaging of the mixed oil flow.

Linescan images were obtained that gave off the dyed (scarlet) oil. Digital video shows the distribution of dye in the volume of agitated glass as a function of position and time in the reference plane. The image is greenish, filtered and processed to maximize contrast. Coarse parabolic dye fronts characterize fully developed pipe flows.

Partial uniformity of the oil is evaluated from the intensity contrast of the image. For example, low contrast indicates good mixing and high contrast is poor. This is shown in FIGS. 8A and 8B, respectively.

The measure of uniformity can be quantified through numerical interrogation of bitmapped intensity data, which is shown in FIG. 9, which is a graph of intensity versus pixel distance. Contrast is obtained as a function of the partial deformation of intensity in the image, and dispersion is obtained as a function of the characteristic log normal peak and the pulse decay of the dye. Dispersion and uniformity numbers are combined to yield an overall index of stirrer effectiveness (SEI), and for the stirrers investigated in this study, sizes between approximately 0 and approximately 4000 indicate higher numbers of superior agitation. 10 is a graphical representation of agitation effectiveness versus shear rate. The measurement is generally different from the stirring efficiency, E, but is believed to behave in the same way as E. In general, E is the ratio of the boundary surface area between the nonuniformity in the glass and the mother glass itself after stirring to before stirring.

For example, in a golf ball the interface is the surface of the ball in contact with water, ie the outer surface of the ball. However, if the ball is cut into small pieces and thrown into the water, the boundary surface area between the ball and the water will be the sum of the surface areas of all particles. This will be much larger than the surface area of the original ball. Thus, the ratio of the cut out boundary area to the cut out before the ball is a large number and is a measure of how finely the ball can be cut. The basis in the above formula is the theoretical derivation of the ratio of the boundary surface area before and after stirring. This is an interesting concept but not easily measured. In the embodiment embodiment of FIG. 7, another measure of the effectiveness of the agitation is used. It is based on observing the distinct elements of the traces left in the stirring vessel, measuring the strength and the space of the line.

As shown in FIG. 10, the stirring effectiveness is increased by increasing the bond distance from 5/16 "to approximately 5/8" and then falls back in the larger blade-wall space. In particular, the stirring effectiveness index increases with the coupling distance of the curves 1001, 1002, 1003 and decreases with the bonding distance of the curves 1004, 1005, and 1006. This indicates that the best equilibrium between bonding distance, blade surface area and rotational speed is present for this class of stirrers, and in producing these variables result in reduced cord loading and reduced platinum content from stir erosion. Indicates that it can be calculated.

It is preferred that the peak SEI in FIG. 10 be as high as possible and occur at the lowest possible shear rate or shear stess. However, for some extensions it must sometimes be trade-off or compromise. For example, curve 105 (combination of 0.75 ") has the second highest SEI peak of the curve of the embodiment embodiment of Figure 10. However, this peak occurs at a relatively high shear rate. Combination of 5/8" At a lower shear rate (or shear stress) a much higher SEI peak is obtained in curve 1003, which is the SEI versus shear rate for the stirrer with. Curve 1004 has a shear rate that is lower than the peaks of curves 1003 and 10005, and the shear rate at the peaks of curves 1003 and 10005. As such, it may be useful to provide a model as described in connection with FIG. 10 to determine which bond and hence which elements provide the optimal SEI and minimum shear rate.

Example embodiments have been described in detail in connection with the discussion of example embodiments, and modifications of the invention will be apparent to those skilled in the art having the benefit of this disclosure. Such modifications and variations are included within the scope of the appended claims.

Claims (22)

Flowing the molten glass through a stir chamber in which a stirrer is placed, wherein a coupling distance between the stirrer and the inner wall of the stirrer chamber is from 0.7938 cm to 1.905 cm; Ratting the stirrer at a speed N where the shear rate produces less than 15 s ⁻¹ ; And agitation efficiency E is in the range of 175 to 250. A method of forming a glass with reduced inclusions and cords. The method of claim 1, wherein the shear stress at a viscosity of 1000 poise in the molten glass is 0.0189 kg / cm ² to 0.0096 kg / cm ² . . The method of claim 1, wherein the temperature of the Morton glass is between 1430 and 1480 ° C. 3. The method of claim 1, wherein the inclusions included in the Morton glass exiting the stir chamber are less than 50 μm in diameter. 2. The glass of claim 1 wherein the intensity contrast of the cords contained in the molten glass exiting the stir chamber is less than 0.67%. Way. delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete

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