WO2012044904A2

WO2012044904A2 - Method to reduce adhered glass from lcd substrate

Info

Publication number: WO2012044904A2
Application number: PCT/US2011/054168
Authority: WO
Inventors: Douglas E. Mcelheny; Glen R. Moseley; Liming Wang
Original assignee: Corning Incorporated
Priority date: 2010-09-30
Filing date: 2011-09-30
Publication date: 2012-04-05
Also published as: TWI571446B; WO2012044904A3; TW201219324A

Abstract

A method of making a sheet of glass comprises the steps of machining a target area of a strip of glass, wherein glass fragments are formed and detach from the strip of glass, and applying a slip agent on the glass fragments. Moreover, an apparatus for making a sheet of glass includes a machining tool including an edge configured to machine a target area of a strip of glass such that glass fragments are formed and detach from the strip of glass; and an emitting device configured to apply a slip agent on the glass fragments.

Description

METHOD TO REDUCE ADHERED GLASS FROM LCD SUBSTRATE

This application claims the benefit of priority under 35 U.S.C. § 1 19 of U.S.

Provisional Application No. 61/388141 filed on September 30, 2010 the content of which is relied upon and incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to methods and apparatus for manufacturing sheets of glass, and more particularly, methods and apparatus for reducing defects in the

manufacturing of sheets of glass.

BACKGROUND

The manufacturing of glass sheets involves various processes in which the sheet of glass is brought to a desired shape by the application of force or friction, as in cutting, grinding, beveling, polishing or the like. Such processes generate fragments or chips of glass that can adhere to the sheet of glass which is in the process of solidifying thereby resulting in a defective sheet of glass. Thus, there is a need for a method or an apparatus for reducing the frequency of a defective product.

SUMMARY

Several aspects of the present invention are disclosed herein. It is to be understood that these aspects may or may not overlap with one another. Thus, part of one aspect may fall within the scope of another aspect, and vice versa.

Each aspect is illustrated by a number of embodiments, which, in turn, can include one or more specific embodiments. It is to be understood that the embodiments may or may not overlap with each other. Thus, part of one embodiment, or specific embodiments thereof, may or may not fall within the ambit of another embodiment, or specific embodiments thereof, and vice versa.

A first aspect of the present disclosure relates to a method of making a sheet of glass, comprising the steps of:

a. machining a target area of a strip of glass, wherein glass fragments are formed and detach from the strip of glass; and

b. applying a slip agent on the glass fragments. In certain embodiments of the first aspect of the present disclosure, the step of machining cuts through a ribbon of glass made from a fusion draw process to form the sheet of glass.

In certain embodiments of the first aspect of the present disclosure, the method further includes the step of changing the target area of the strip of glass during the step of machining.

In certain embodiments of the first aspect of the present disclosure, the slip agent is directed toward the target area of the strip of glass and a proximity of the target area.

In certain embodiments of the first aspect of the present disclosure, the step of applying the slip agent is performed by spraying.

In certain embodiments of the first aspect of the present disclosure, the step of applying the slip agent is performed simultaneously with the step of machining.

In certain embodiments of the first aspect of the present disclosure, the step of machining alters a contour of a peripheral edge of the strip of glass.

In certain embodiments of the first aspect of the present disclosure, a fluid for removing a bulk of the glass fragments from the strip of glass is applied to the target area, and the fluid includes the slip agent.

In certain embodiments of the first aspect of the present disclosure, the fluid cools the strip of glass.

In certain embodiments of the first aspect of the present disclosure, the method further includes the step of removing the slip agent from the target area of the strip of glass and the proximity of the target area.

A second aspect of the present disclosure relates to an apparatus for making a sheet of glass, including:

(I) a machining tool including an edge configured to machine a target area of a strip of glass such that glass fragments are formed and detach from the strip of glass; and

(II) an emitting device configured to apply a slip agent on the glass fragments. In certain embodiments of the second aspect of the present disclosure, the emitting device is oriented toward the target area of the strip of glass and a proximity of the target area.

In certain embodiments of the second aspect of the present disclosure, the tool is configured to move about a ribbon of glass such that the target area of the strip of glass changes, and the emitting device is configured to move so as to be oriented toward the target area and the proximity of the target area.

In certain embodiments of the second aspect of the present disclosure, as the tool moves, the emitting device is configured to leave a layer of the slip agent on the target area and the proximity of the target area.

In certain embodiments of the second aspect of the present disclosure, the machining tool includes a wheel configured to rotate.

In certain embodiments of the second aspect of the present disclosure, the edge of the machining tool is positioned to machine a peripheral edge of a sheet of glass.

In certain embodiments of the second aspect of the present disclosure, the edge of the machining tool is positioned to machine a face of a ribbon of glass.

One or more embodiments and/or aspects of the present disclosure have one or more of the following advantages. First, the application of a slip agent coating on the glass particles is believed to significantly reduce the number of glass particles adhered to the glass surface during glass finishing. Second, it is further believed that, even if particles still adhere to the glass surface, due to the application and presence of slip agent, the adhesion force is reduced, making down-stream removal in washing and cleaning facilities and steps much easier ad more effective. Third, the application of the slip agent can be carried out conveniently in a nozzle that supplies cooling fluid to the glass surface during a glass finishing process, resulting in easy retrofitting of this technology into prior, existing glass finishing lines.

Additional features and advantages of the invention will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from the description or recognized by practicing the invention as described in the written description and claims hereof, as well as the appended drawings. It is to be understood that the foregoing general description and the following detailed description are merely exemplary of the invention, and are intended to provide an overview or framework to understanding the nature and character of the invention as it is claimed.

The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects are better understood when the following detailed description is read with reference to the accompanying drawings, in which:

FIG. 1 is a schematic view of a glass manufacturing system;

FIG. 2 is a side view of an example embodiment of a first apparatus for reducing adhered glass fragments from a strip of glass; and

FIG. 3 is a side view of an example embodiment of a second apparatus for reducing adhered glass fragments from a strip of glass.

DETAILED DESCRIPTION

Examples will now be described more fully hereinafter with reference to the accompanying drawings in which example embodiments are shown. Whenever possible, the same reference numerals are used throughout the drawings to refer to the same or like parts. However, aspects may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

High quality thin glass sheets can be produced through a fusion process such as an overflow downdraw process. FIG. 1 shows an example embodiment of a glass

manufacturing system 101, or a fusion draw machine, more specifically, that implements the fusion process for manufacturing a glass sheet 117. The glass manufacturing system 101 may include a melting vessel 103, a fining vessel 105, a mixing vessel 107 (e.g., the illustrated stir chamber), a delivery vessel 109 (e.g., the illustrated bowl), a forming vessel 111 (e.g., the illustrated isopipe), a pull roll assembly 113 and a traveling anvil machine 115 (TAM).

The melting vessel 103 is where the glass batch materials are introduced as shown by arrow 119 and melted to form molten glass 121. The fining vessel 105 has a high temperature processing area that receives the molten glass 121 from the melting vessel 103 and in which bubbles are removed from the molten glass 121. The fining vessel 105 is connected to the mixing vessel 107 by a finer to stir chamber connecting tube 123.

Thereafter, the mixing vessel 107 is connected to the delivery vessel 109 by a stir chamber to bowl connecting tube 125. The delivery vessel 109 delivers the molten glass 121 through a downcomer 127 to an inlet 129 and into the forming vessel 111. The forming vessel 111 includes an opening 131 that receives the molten glass 121 which flows into a trough 133 and then overflows and runs down two sides of the forming vessel 111 before fusing together at what is known as a root 135. The root 135 is where the two sides come together and where the two overflow walls of molten glass 121 rejoin before being drawn downward by the pull roll assembly 113 to form the glass ribbon 137. Then, the TAM 115 scores the drawn glass ribbon 137 which is then separated into individual glass sheets 117. The glass sheets 117 may undergo further machining processes, such as additional cutting, grinding, beveling, polishing or the like, which can produce fragments or chips of glass that can attach or adhere to the panel from which they were attached due to van der Waals forces. The glass sheets 117 may need to meet precise dimensional requirements, such as for use as LCD panels, and the adhesion of these glass fragments can result in defective products.

Referring now to FIG. 2, a first machining process generating glass fragments 201 is shown. A first embodiment of a machining tool 203 that is part of the glass manufacturing system 101 is shown and, in one example, may be a first wheel 205 that rotates about an axis A and includes a sharp edge 207 functioning as a blade. In this embodiment, the axis A is parallel with a strip 209 of glass which may be disposed vertically, horizontally or at an angle. While FIG. 2 shows the machining tool 203 embodied as a cutter with a rotating circular blade, the blade may be polygonal (e.g., rectangular) or may not rotate. The machining tool 203 may be configured such that the location of the axis A can be moved to various locations and such that the sharp edge 207 can be brought into and out of contact with the strip 209 of glass for cutting across a face of the strip 209 of glass.

The term "strip" is used to encompass glass at various stages of manufacturing and may refer to a continuous ribbon 137 of glass, a separate sheet 117 of glass that has been cut from the ribbon 137, or forms of glass at other stages of manufacturing. Thus, the machining tool 203 in FIG. 2 may, for example, be part of the TAM 115 cutting across a ribbon 137 of glass at a bottom of a draw in the fusion draw machine or, alternately, may operate in a vertical bead scoring region (not shown) at the bottom of the draw and cut off bead sections of the ribbon 137 on which the pull roll assembly 113 may have left marks.

The sharp edge 207 of the first wheel 205 contacts and machines a target area 211 on the strip 209 of glass where glass fragments 213 form and detach from. FIG. 2 is not drawn to scale and the size of some of the glass fragments 213 may be illustrated in an exaggerated fashion. The target area 211 refers to an area of the strip 209 of glass that is processed or machined by a machining tool 203 and may be the portion of the strip 209 of the glass that is in contact with the machining tool 203. Also, the glass fragments 213 may or may not be similarly sized. As further shown in FIG. 2, the glass manufacturing system 101 may include a first emitting device 215 that is in fluid communication with a container 219 supplying a slip agent 217. The first emitting device 215 may be a nozzle, for example. The first emitting device 215 is oriented toward the target area 211 and sprays the slip agent 217 to the target area 211 and a proximity thereof although the first emitting device 215 can be disposed or oriented in a variety of ways. Moreover, a plurality of first emitting devices 215 can be used and, for example, another first emitting device 215 may be disposed on an opposite end of the first wheel 205 (FIG. 2) or for an opposite surface of the strip 209 of glass (FIG. 3). The first emitting device 215 is intended to coat, by way of spraying, for example, the exterior of the glass fragments 213 with the slip agent 217 such that a barrier layer 223 of the slip agent 217 forms a boundary between a glass fragment 213 and the strip 209 of glass. The barrier layer 223 may be made of droplets 221 of the slip agent 217 that are spaced apart, as shown in FIG. 2, in which case the barrier layer 223 is discontinuous and gaps exist between the droplets 221. Alternatively, the barrier layer 223 may be a continuous layer of the slip agent 217. The presence of the barrier layer 223 can prevent the glass fragments 213 from becoming adhered to the strip 209 of glass.

Application of the slip agent 217 on the target area 211 and its proximity also leaves a deposit layer 225 of slip agent 217 over the strip 209 of glass that is distinct from the barrier layer 223 formed on the exterior of the glass fragments 213. While the deposit layer 225 is shown as a continuous layer, it may be formed of droplets of slip agent similarly to the barrier layer 223. The spraying leaves the deposit layer 225 of slip agent 217 over the strip 217 using water and detergent, for example. Because a thinner deposit layer 225 is easier to remove during the cleaning stage, a first emitting device 215 may be selected taking into consideration its ability to form a thin deposit layer 225. For example, the deposit layer 225 may have a nanoscale thickness, such as 15 nanometers or less.

The first emitting device 215 is located about the target area 211 such that the slip agent 217 can be applied to a large number of the glass fragments 213 at the target area 211 and its proximity. The location and the orientation of the first emitting device 215 can be determined based on factors such as the distance reached upon spraying, the angle of expansion of the slip agent 217 when sprayed, etc.

The slip agent 217 may be applied to the glass fragments 213 as the glass fragments 213 are in the process of detaching and/or after the glass fragments 213 have detached.

Moreover, the glass fragments 213 may undergo various kinds of random movement after the glass fragments 213 are detached completely from the strip 209 of glass. The glass fragments 213 may undergo some rotation in addition to displacement from the strip 209 of glass as the glass fragments 213 move away from the strip 209 of glass after becoming detached. Such rotation and other random movement of the glass fragments 213 can help coat a larger portion of the outer surface of a glass fragment 213 and can increase the possibility that a barrier layer 223 of slip agent 217 will be provided as an adequate boundary between the strip 209 of glass and a glass fragment 213.

The composition of the slip agent of any of the embodiments of the disclosure may be determined based on factors such as the ability to protect the strip 209 from scratching, the ease of removability during the washing process, etc. and may be formed of long chain fatty ester or long chain fatty amide, for example.

The machining tool 203 may be moved about the strip 209 of glass such that the target area 211 on which the machining tool 203 operates changes. For example, the machining tool 203 may gradually be moved to the left in FIG. 2 to cut across the strip 209 of glass as indicated by an arrow 227. The first emitting device 215 may be configured to move along with the machining tool 203 so that the first emitting device 215 accordingly follows the target area 211 from which the glass fragments 213 are generated and its proximity. This may be accomplished, for example, by configuring the first emitting device 215 as part of the same subsystem of the glass manufacturing system 101 on which the machining tool 203 is mounted although other means known in the art can also be utilized. While FIG. 2 shows the first emitting device 215 as being mounted to the left of the first wheel 205 or ahead of the machining tool during movement, the first emitting device 215 may be located at various positions about the machining tool 203 and one or more first emitting devices 215 may be provided as shown.

The first emitting device 215 may begin to spray the slip agent 217 before or simultaneously with the start of operation of the machining tool 203 during which glass fragments 213 are generated. Alternatively, the first emitting device 215 may begin to spray the slip agent 217 after the machining tool 203 has begun to operate as long as the spraying of the slip agent 217 can cover a high number of glass fragments 213 despite some delay in the start of operation.

Referring now to FIG. 3, a second machining process 301 generating glass fragments 213 and a second embodiment of the machining tool 303 are shown. The machining tool 303 may be a second wheel 305 that rotates about an axis B that is perpendicular to the strip 209 of glass being machined. The second wheel 305 may be made of an abrasive material and may include an abrasive edge 307 for grinding, beveling, or polishing an edge of the strip 209 of glass. For example, as shown in FIG. 3, the abrasive edge 307 may include a groove 309 that extends peripherally and has a V-shaped cross-section such that a peripheral edge 311 of the strip 209 of glass can be accommodated within the groove 309. However, the cross-sectional shape of the groove 309 may vary and, for example, the groove 309 may be concave or convex. Alternatively, the abrasive edge 307 of the second wheel 305 may simply be planar. Moreover, there may be multiple ways of disposing an abrasive edge 307 having a given cross-sectional shape about the strip 209 of glass and an abrasive edge 307 having a different shape may contact the peripheral edge 311 in a different manner.

Similarly to FIG. 2, machining of the strip 209 of glass in FIG. 3 may alter a contour 313 of the peripheral edge 311 of the strip 209 of glass while generating in the process glass fragments 213 that can adhere to the strip 209 of glass. In this embodiment, the first emitting device 215 in FIG. 3 is disposed perpendicularly about the strip 209 of glass. However, the first emitting device 215 may be oriented in alternative ways and the target area 317 for spraying of the slip agent 217 may be, for example, the corners of the peripheral edge 311 contacting the abrasive edge 307.

Different types of machining processes can generate different amounts of glass fragments 213. For example, a process of altering the contour 313 of the peripheral edge 311 may require removing a larger amount of glass fragments from the strip 209 of glass compared to a cutting process. In the machining process of FIG. 3, the second wheel 305 may machine the target area 317 of the strip 209 of glass for an extended period of time whereas, in the machining process of FIG. 2, the amount of time spent at each target area 211 by the first wheel 205 may be much shorter. In such a case, a second emitting device 327 that can supply a larger amount of fluid 319 compared to the first emitting device 215 may be used to remove the larger amount of glass fragments 213 away from the strip 209 of glass. The fluid 319 can be composed solely of the slip agent 217 or, alternatively, a mixture of the slip agent 217 and one or more additional substances. This may be accomplished by supplying a flow of fluid 319 at a larger volume rate to the target area 317 and may be by way of spraying, injecting, pouring, or the like. Thus, a bulk of the glass fragments 213 may be removed from the strip 209 of glass by the flow of fluid 319 moving over the target area 317.

While FIG. 3 shows the first and second emitting devices 215, 327, it may be possible to provide the second emitting device 327 by itself without providing the first emitting device 215. Depending on the type of emitting device that is implemented, it may be possible to merely apply coating on the glass fragments 213 or to provide fluid 319 in sufficient quantity that the bulk of the glass fragments 213 can be removed and the glass fragments 213 remaining on the strip 209 of glass are coated with a barrier layer 321 formed of droplets 323 of the slip agent 217. The fluid 319 may provide an additional function of cooling the strip 209 of glass around the target area 317 which may have become heated due to the extended period of machining. Similarly to FIG. 2, a deposit layer 325 formed by the fluid 319 and/or the slip agent 217 can be cleaned from the strip 209 of glass using washing processes. Similarly to the machining tool 203 of FIG. 2, the machining tool 303 may be moved about the strip 209 of glass albeit not in an identical manner. For example, the machining tool 303 may be moved along the peripheral edge 311 of the strip 209 of glass to evenly machine the peripheral edge 311 of the strip 209 of glass. Alternatively, the strip 209 of glass may be moved while the machining tool 303 is stationary.

It will be apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit and scope of the claimed invention.

Claims

1. A method of making a sheet of glass, comprising the steps of:

b. applying a slip agent on the glass fragments.

2. The method of claim 1, wherein the step of machining cuts through a ribbon of glass made from a fusion draw process to form the sheet of glass.

3. The method of claim 1 or claim 2, further including the step of changing the target area of the strip of glass during the step of machining.

4. The method of any of the preceding claims, wherein the slip agent is directed toward the target area of the strip of glass and a proximity of the target area.

5. The method of any of the preceding claims, wherein the step of applying the slip agent is performed by spraying.

6. The method of any of the preceding claims, wherein the step of applying the slip agent is performed simultaneously with the step of machining.

7. The method of any of the preceding claims, wherein the step of machining alters a contour of a peripheral edge of the strip of glass.

8. The method of any of the preceding claims, wherein a fluid for removing a bulk of the glass fragments from the strip of glass is applied to the target area, and the fluid includes the slip agent.

9. The method of claim 8, wherein the fluid cools the strip of glass.

10. The method of any of the preceding claims, further including the step of removing the slip agent from the target area of the strip of glass and the proximity of the target area.

11. An apparatus for making a sheet of glass, including:

(I) a machining tool including an edge configured to machine a target area of a strip of glass such that glass fragments are formed and detach from the strip of glass; and (II) an emitting device configured to apply a slip agent on the glass fragments.

12. The apparatus of claim 11, wherein the emitting device is oriented toward the target area of the strip of glass and a proximity of the target area.

13. The apparatus of claim 11 or claim 12, wherein the tool is configured to move about a ribbon of glass such that the target area of the strip of glass changes, and the emitting device is configured to move so as to be oriented toward the target area and the proximity of the target area.

14. The apparatus of claim 13, wherein, as the tool moves, the emitting device is configured to leave a layer of the slip agent on the target area and the proximity of the target area.

15. The apparatus of any of the preceding claims 11 to 14, wherein the machining tool includes a wheel configured to rotate.

16. The apparatus of claim 15, wherein the edge of the machining tool is positioned to machine a peripheral edge of a sheet of glass.

17. The apparatus of claim 15 or claim 16, wherein the edge of the machining tool is positioned to machine a face of a ribbon of glass.