This disclosure relates to apparatuses and methods of forming flexible glass laminates by electrostatically pinning together a flexible glass substrate and a laminate substrate with an adhesive.
During manufacturing, glass can be formed as a continuous substrate web. The thickness of final glass product is determined when the glass cools and solidifies. Depending on the final use for the manufactured glass, the glass may be subject to certain thickness requirements. For example, glass used in applications such as electronic displays or touchscreens may benefit from a thickness of 0.3 millimeter or less. Customers for these applications require a consistent web surface that is free from particles, debris, damage or other surface non-uniformities. The thickness of a glass substrate web can directly affect the flexibility, surface sensitivity, air entrainment and consistency of the flexible glass web. For glass substrate webs with a thickness of 0.3 millimeter or less, the resulting increased flexibility of the glass substrate web enables roll to roll processing which creates a need for special handling procedures during and after the glass manufacturing process. Also, increased surface sensitivity may lead to an increased probability for cracks (relative to that for thicker substrate webs) and fractures on the surface of the glass substrate web. These conditions lead to difficulty in handling flexible glass substrate webs without causing breakage or otherwise damaging the flexible glass substrate. As a result, flexible glass substrate webs may be protected during processing, transport, or other manufacturing with the help of a laminate or through a lamination process. Current lamination technology is designed for metals, plastics, or paper webs and may use high pressure and heat that are potential causes of damage to flexible glass substrate webs. Accordingly, alternative handling and lamination measures for flexible glass substrate webs are needed to ensure the flexible glass substrate web is free of air bubbles and is not damaged prior to use in final applications.
Embodiments disclosed herein include apparatuses and methods of forming flexible glass laminates. The flexible glass laminates disclosed herein can be formed with a laminate substrate. As a non-limiting example, the flexible glass laminates can be formed by electrostatically pinning a flexible glass substrate and a laminate substrate together with an adhesive layer there between.
According to a first aspect, a method of forming a flexible glass laminate is provided that comprises:
charging a flexible glass substrate with an electrostatic charge;
charging a laminate substrate with an electrostatic charge that has a polarity opposite a polarity of the charge on the flexible glass substrate;
bringing the flexible glass substrate and the laminate substrate together, with an adhesive therebetween, thereby creating an adhesive bond and an electrostatic bond between the flexible glass substrate and the laminate substrate.
According to a second aspect, there is provided the method of aspect 1, further comprising treating the adhesive using a treatment device.
According to a third aspect, there is provided the method of aspect 1 or aspect 2, wherein the treatment device is a heating device.
According to a fourth aspect, there is provided the method of aspect 1 or aspect 2, wherein the treatment device is an ultraviolet light device.
According to a fifth aspect, there is provided the method of any one of aspects 1-4, wherein the electrostatic charge creates an electrostatic bond such that the shear force required to cause slip between the flexible glass substrate and laminate substrate is greater than the shear force required to cause slip between the flexible glass substrate and laminate substrate with the adhesive bond alone.
According to a sixth aspect, there is provided the method of any one of aspects 1-5, further comprising applying the adhesive to at least one of the laminate substrate and the flexible glass substrate before creating the electrostatic bond between the laminate substrate and the flexible glass substrate.
According to a seventh aspect, there is provided the method of any one of aspects 1-6, wherein the flexible glass substrate has a thickness of 0.3 millimeter or less.
According to a eighth aspect, there is provided the method of any one of aspects 1-7, further comprising using nip rollers to apply pressure to the laminate substrate and the flexible glass substrate.
According to a ninth aspect, a flexible glass laminate forming apparatus is provided that comprises:
a charge generator;
a first charging head connected to the charge generator capable of applying an electrostatic charge to a flexible glass substrate;
a second charging head connected to the charge generator capable of applying an opposite electrostatic charge to a laminate substrate, wherein the second charging head is positioned opposite the first charging head; and
an adhesive application device that applies adhesive to a surface of at least one of the laminate substrate and the flexible glass substrate to form an adhesive bond between the flexible glass substrate and laminate substrate.
According to a tenth aspect, there is provided the flexible glass laminate forming apparatus of aspect 9, further comprising a treatment device that is used to treat the adhesive.
According to a eleventh aspect, there is provided the flexible glass laminate forming apparatus of aspect 9 or aspect 10, wherein the treatment device is a heating device.
According to a twelfth aspect, there is provided the flexible glass laminate forming apparatus of aspect 9 or aspect 10, wherein the treatment device is an ultraviolet light device.
According to a thirteenth aspect, there is provided the flexible glass laminate forming apparatus of any one of aspects 9-12, further comprising an application nozzle that controls an amount and location of adhesive applied to the surface of at least one of the laminate substrate and the flexible glass substrate.
According to a fourteenth aspect, there is provided the flexible glass laminate forming apparatus of any one of aspects 9-13, further comprising nip rollers that apply pressure to the flexible glass laminate.
According to a fifteenth aspect, a flexible glass laminate is provided that comprises: a flexible glass substrate with an electrostatic charge;
a laminate substrate with an opposing electrostatic charge to form an electrostatic bond with the flexible glass substrate; and
an adhesive between the flexible glass substrate and the laminate substrate forming an adhesive bond between the flexible glass substrate and the laminate substrate.
According to a sixteenth aspect, there is provided the flexible glass laminate of aspect 15, wherein the flexible glass laminate is wound into a roll.
According to a seventeenth aspect, there is provided the flexible glass laminate of aspect 15, wherein the flexible glass laminate is a discrete sheet.
According to a eighteenth aspect, there is provided the flexible glass laminate of any one of aspects 15-17, wherein the laminate substrate comprises multiple strips of the laminate substrate positioned along a width of the flexible glass substrate.
According to a nineteenth aspect, there is provided the flexible glass laminate of any one of aspects 15-18, wherein the flexible glass substrate has a thickness of about 0.3 millimeter or less.
According to a twentieth aspect, there is provided the flexible glass laminate of any one of aspects 15-19, wherein the laminate substrate has a width less than the width of the flexible glass substrate.
Additional features and advantages will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the embodiments as described herein, including the detailed description that follows, the claims, as well as the appended drawings.
It is to be understood that both the foregoing general description and the following detailed description embodiments are intended to provide an overview or framework for understanding the nature and character of the disclosure. The accompanying drawings are included to provide a further understanding, and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments, and together with the description serve to explain the principles and operation of the concepts disclosed.
Embodiments disclosed herein generally relate to forming flexible glass laminates using electrostatic pinning and an adhesive. A flexible glass substrate and a laminate substrate with an adhesive can be joined using electrostatic pinning, creating an intimate initial laminated glass surface. As will be discussed in greater detail below, the adhesive bond can increase in bond strength over time, with a longer term bond forming as the adhesive spreads between the flexible glass substrate and the laminate substrate.
The flexible glass substrate web 130 may be supplied from an upstream process 161, for example a forming process or a conveyance process in connection with using or manipulating the flexible glass substrate web 130. The forming process may be a down draw, slot draw, fusion draw, float, or other similar process. For example, a fusion process (e.g. a downdraw process) forms high quality thin glass sheets that can be used in a variety of devices, for example flat panel displays. Glass sheets or webs formed in a fusion process have surfaces with superior flatness and smoothness when compared to glass sheets formed by other methods. The fusion process is described in U.S. patent Ser. Nos. 3,338,696 and 3,682,609. The flexible glass substrate web 130 may be “ultra-thin” having a thickness of about 0.3 mm or less, including, but not limited to, thicknesses of, for example, about 0.01-0.05 mm, about 0.05-0.1 mm, about 0.1-0.15 mm, about 0.15-0.3 mm, for example 0.3, 0.29, 0.28, 0.27, 0.26, 0.25, 0.24, 0.23, 0.22, 0.21, 0.2, 0.19, 0.18, 0.17, 0.16, 0.15, 0.14, 0.13, 0.12, 0.11, 0.1, 0.09, 0.08, 0.07, 0.06, and 0.05 mm.
The conveyance process may include conveying the flexible glass substrate web 130 through a manufacturing apparatus or processing the flexible glass substrate web 130. Further examples of processes in which the flexible glass substrate web 130 may be conveyed include any step subsequent to the formation of the glass, for example grinding, polishing, cleaning, the formation of thin film devices on the glass, cutting, splicing, rolling from another roll, etching processes, or lamination to other films or structures.
The laminate substrate web 120 may be supplied in a roll 122 having a central longitudinal axis 123. The roll 122 may rotate in the direction of arrow 124 as laminate substrate web 120 is pulled into roll 160. The laminate substrate web 120 has a width 125 and a thickness 126 (shown in
The apparatus 100 includes a charge generator 150 or other device to create electrostatic charges and may include a treatment device 140 for treating the adhesive 110. In some embodiments, the flexible glass substrate web 130 is fed from the upstream process 161 along direction 131, past a first charging head 152 and toward the roll 160, which rotates in a direction of arrow 162. At or about the same time the flexible glass substrate web 130 is fed toward the roll 160, the laminate substrate web 120 is unwound from the roll 122 rotating in direction of arrow 124 and is fed along direction 133. The laminate substrate web 120 is positioned relative to the roll 160 and to a second charging head 154 by rollers 121. In one embodiment, before reaching the second charging head 154, the laminate substrate web 120 passes under the application device 112, where adhesive 110 is applied to the laminate substrate web 120. The adhesive 110 is applied via an application nozzle 114, and can be applied in various patterns, amounts or densities, for example as a dot pattern (shown in
Electrostatic charges are applied to the laminate substrate web 120 and flexible glass substrate web 130 by the charge generator 150, which is coupled to the first charging head 152 and the second charging head 154 via connections 155. The first charging head 152 is placed near the flexible glass substrate web 130 and may apply a negative charge to the flexible glass substrate web 130, and the second charging head 154 is placed near the laminate substrate web 120 and may apply a positive charge to the laminate substrate web 120, or vice versa. The charging heads 152, 154 can add charge to the laminate substrate web 120 and flexible glass substrate web 130 rather than polarize the existing charges in the laminate substrate web 120 and flexible glass substrate web 130. The amount of charge to be added so as to pin the flexible glass substrate web 130 with the laminate substrate web 120 can depend upon, among other things, the thickness 134 of the flexible glass substrate web 130, and the characteristics of the laminate substrate web 120, for example its thickness 126 (shown in
In some embodiments, the apparatus 100 may include a roller 170, or more than one roller 170 so as to form a nip. In one embodiment, the roller 170 makes contact with the laminate substrate web 120 and applies pressure to enhance the electrostatic and adhesive bonds between the laminate substrate web 120 and flexible glass substrate web 130. The treatment device 140 may be positioned downstream from the roller 170 in the apparatus 100. The treatment device 140 can be any device used for treating the adhesive 110 between the laminate substrate web 120 and flexible glass substrate web 130, for example a heating or other temperature control device or an ultraviolet light device that provides an ultraviolet light in order to activate the adhesive 110 or enhance the bonds between the laminate substrate web 120 and flexible glass substrate web 130. The electrostatically pinned and adhesively bonded laminate substrate web 120 and flexible glass substrate web 130 may then be rolled together into the roll 160, wherein successive wraps of laminate substrate web 120 and flexible glass substrate web 130 are also electrostatically pinned to one another to keep the successive wraps from sliding relative to one another during transportation or storage of the roll 160. Alternatively, discrete sheets of electrostatically pinned laminate substrate web 120 and flexible glass substrate web 130 may then be segmented and stacked, where successive layers in the stack are also electrostatically pinned to one another.
Referring to
The adhesive 110 can be different types of adhesives, such as contact adhesives, thermal adhesives, synthetic adhesives, and the like. The bonding chemistry and pattern in which the adhesive 110 is applied can affect the adhesive bond strength and amount of adhesive 110 applied to the laminate substrate web 120. Also, the apparatus 100 may be differently configured depending upon the type of adhesive 110 applied. For example, a thermal treatment device 140 may be used when applying a thermally activated adhesive, or an ultraviolet treatment device 140 may be used when applying an ultraviolet activated adhesive. Other adhesives, for example a pressure sensitive adhesive, synthetic adhesive, or a contact adhesive can also be used with the apparatus 100. As the adhesive 110 is forced into contact with the flexible glass substrate web 130 and the laminate substrate web 120 via the action of the electrostatic forces, an adhesive bond is formed. In some embodiments, wherein the adhesive does not exist over the entire area of overlap between the flexible glass substrate web 130 and the laminate substrate web 120, the strength of the adhesive bond increases over time as the adhesive 110 spreads. This is due to the electrostatic force bringing the flexible glass substrate web 130 together with the laminate substrate web 120 in order to cover a larger surface area between the laminate substrate web 120 and the flexible glass substrate web 130. Additionally, as the electrostatic forces bring together the flexible glass substrate web 130 and the laminate substrate web 120, air entrainment may be reduced or prevented and air may be excluded and/or pushed from between the laminate substrate web 120 and the flexible glass substrate web 130 as the adhesive 110 spreads via the force of the webs coming together. The use of electrostatic force may remove the need for other external pressures to be applied by nip rollers, for example. In some embodiments, the adhesive 110 may be applied to the flexible glass substrate web 130 or both the flexible glass substrate web 130 and the laminate substrate web 120.
Referring to
Still referring to the embodiment illustrated in
The flexible glass substrate web 130 forming process can produce variations in the thickness 134 of the flexible glass substrate web 130 across its width 132. Also, during a standard lamination process, the flexible glass substrate web 130 can crack or develop other surface defects. When the flexible glass web is less than about 0.3 millimeter thick, the propensity for developing cracks may increase. These cracks and surface defects can propagate and reduce yields. By using a process of electrostatically pinning the flexible glass substrate web 130 to a laminate substrate web 120 that has adhesive 110 any cracks that occur may be prevented from further propagating because the flexible glass substrate web 130 is laminated to the laminate substrate web 120 via electrostatic and adhesive bonds. By applying electrostatic charges to the laminate substrate web 120 and flexible glass substrate web 130, an attraction between successive layers of laminate substrate web 120 and flexible glass substrate web 130 is developed, which can allow straight side walls to be formed and increase stability of the stack or roll of electrostatically pinned laminate and glass. The electrostatically pinned laminate with adhesive also provides a functional surface that can be used for lens patterns or textures and also serves as a protective film during set up for processing or conveyance. The electrostatic charge may be removed by application of a de-ionizing field. The flexible glass substrate web 130 and the laminate substrate web 120 may remain bonded together by the adhesive 110, even after removal of the electrostatic charge. Adhesive chemistry can be used to reverse bonding of the adhesive 110 to the glass surface to release the flexible glass substrate web 130 from the laminate substrate web 120.
Many modifications and other embodiments of the embodiments set forth herein will come to mind to one skilled in the art to which the embodiments pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the description and claims are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. It is intended that the embodiments cover the modifications and variations of the embodiments provided they come within the scope of the appended claims and their equivalents. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.
For example, although the adhesive was described as being applied to the laminate substrate web 120, it may alternatively, or in addition, be applied to the glass substrate web 130. It may be advantageous to apply the adhesive to both the laminate substrate web 120 and the glass substrate web 130 in the event that the adhesive is a two-part adhesive and, in such case, one or both parts of the adhesive may be applied to a respective web and rolled for later combination with the corresponding web and adhesive part.
This application claims the benefit of priority under 35 U.S.C. §119 of U.S. Provisional Application Ser. No. 61/762,001 filed on Feb. 7, 2013 the content of which is relied upon and incorporated herein by reference in its entirety.
Filing Document | Filing Date | Country | Kind |
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PCT/US14/14603 | 2/4/2014 | WO | 00 |
Number | Date | Country | |
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61762001 | Feb 2013 | US |