GB2614518A

GB2614518A - Ultra thin polymer coated strengthened glass panel for accepting a thermal dye diffusion image

Info

Publication number: GB2614518A
Application number: GB2113492.9A
Authority: GB
Inventors: David Curtis Andrew
Original assignee: Individual
Current assignee: Individual
Priority date: 2021-09-22
Filing date: 2021-09-22
Publication date: 2023-07-12

Abstract

A method of making an item of ultra-thin flat glass comprises the step of strengthening the glass by ion exchange. The glass can subsequently be coated with a polymer to allow a sublimation image to be applied by heat and pressure in a flatbed heat press. An applied image can be translucent and visible from one or both sides. The glass panel, which can have ground and polished edges and corners, can be 0.1-2mm thick and composed of 70-75 wt% silicon dioxide, 12-16 wt% sodium oxide, 10-19 wt% calcium oxide; and can be strengthened by submersion in a bath of molten potassium nitrate salts at between 420-480ºC for 8-24 hours. The image can then be applied by a sublimation heat transfer process in less than 2 minutes.

Description

DESCRIPTION:

FIELD OF THE INVENTION

1. The present invention relates generally to dye sublimation transfer printing onto synthetic organic polymers and strengthened ultra-thin glass articles with high thermal shock resistance. In greater detail, the invention relates to the production of strengthened ultra-thin clear glass, polymer coated panels that can be decorated by dye-sublimation heat transfer. This invention provides a way to image onto strengthened ultra-thin glass of a thickness between 0.5mm and 2mm without the glass breaking, shattering or cracking due to pressure applied or to thermal shock and stress due to high heat and cooling cycle of the sublimation process, a normal glass panel of thickness 0.5mm to 2mm cannot be used for this purpose as it has the disadvantage of breaking and shattering under the dye sublimation heat transfer process and pressure applied in an heat press used.

BACKGROUND OF THE INVENTION

2. In the field of making glass stronger it is well known that a process used is by potassium ion exchange as disclosed in Corning Glass Works Chemical strengthening method. GB2171990B also US4218230A Method of glass strengthening by ion exchange.

3. In the field of imprinting design onto articles of manufacturer using dye-sublimation, it is well known that images are transferred from a carrier medium using heat and pressure to activate the printed dyes, causing them to turn gaseous through sublimation from their solid state and to subsequently diffuse into a softened polymer matrix under the influence of heat and pressure. For example, an early patent disclosing a dye sublimation transfer was presented in U.S. Pat. No. 4,021,591 issued to Devries. Another sublimation example is shown in a method of imaging a ceramic mug as disclosed in U.S. Pat. No. 4,943,684 issued to Kramer. Other sublimation patent examples 35 U.S.C. §119 and 37 C.F.R. §1.78 of the co-pending U.S. Provisional Application Ser. No. 62/112,114 filed Feb. 4, 2015, for a Thermal Transfer Printed Polymeric Phone Case Insert. All information disclosed in those prior pending provisional applications is incorporated herein by reference.

4. To produce solid articles suitable for dye sublimation decoration, synthetic organic coatings are typically formulated and employed to pre-coat the substrate being decorated prior to the transfer of the image. An example patent disclosing such coatings used prior to the sublimation of images onto ceramic tiles is U.S. Pat. No. 4,174,250 issued to Durand and co-pending U.S. Provisional Application Ser. No. 62/112,119 filed Feb. 4, 2015, for a Curved Acrylic Photo 5. Articles that use a transferred image by a process of dye-sublimation is a heat tempered, polymer coated glass panel, the thickness of the heat tempered glass panel is typically around 4mm to 6mm, this is in order to allow glass to be imaged with dye sublimation on the glass in a stable fashion without the glass breaking or cracking under the heat and cooling cycle and pressure of the heat press for any decorations that might be applied to the panel, such as photographs, heat tempered glass is used because it is tough enough to withstand high temperature and pressure applied by the heat press and has a much higher thermal shock resistance than a normal untreated float glass of the same thickness 6. Glass under a thickness of less than 3mm is deemed unacceptable for heat tempering and sublimation imaging, at this thickness it deforms under the heat tempering process making it unsuitable for dye sublimation imaging. Glass that has not been heat tempered cannot be used due to the thermal shock it experiences and the stress and pressure applied using a heat press, these panels have been available in dimensions of up to 50cm x 70cm, panels with a thickness of less than 4mm to 6mm are not generally decorated due to problems associated with the process of dye sublimation imaging, heat, pressure and cooling process 7. In response articles that have also become popular in recent years for decorating are 6mm panel glass media. Glass is transparent and has a sublimatable polymer coating applied onto one side allowing an image to be viewed through the glass. Also, current techniques and formulations allow for images to be viewed from both sides. Hence, glass media has become popular for gifts and photo displays, and often are decorated for such uses.

8. However, some disadvantages to current 4mm to 6mm thick glass exist namely a relatively high weight, with glass the potential for easy breakage under heat, cooling too fast and pressure of process, safety concerns of breakage.

9. A further disadvantage is that 4mm to 6mm thickness glass panels experience a much longer time to transfer a dye-sublimation image onto the glass article. The transfer of an image by dye-sublimation typically requires 7-15 minutes per image depending upon the process employed, the thickness of glass and coating composition. Therefore, it is time consuming and cannot be ramped up for any volume or industrial production in an efficient, cost effective and timely manner.

10. Strengthened Ultra-thin curved glass does not suffer from these disadvantages and limitations and as such it would be desirable to use ultra-thin glass as a gift article if the glass could be imaged using standard flatbed heat presses readily available, but also be susceptible to the application of a dye-sublimation image in a fast and efficient manufacturing process. The ultra-thin glass panel with a polymer coating can accept a dye sublimation image in between 60 seconds and 80 seconds depending on the heat and process employed due to the thinness of the glass and rapid heating of the thin glass in comparison to thicker items.

11. The ultra-thin glass manufactured through an ion exchange process is also 6 times to 10 times stronger than a normal glass material, so is also very safe in relation to a normal glass plate or current thick heat tempered glass. The ultra-thin glass is also thinner than a standard glass photo frame so is much lighter, easier to handle and cheaper to package and transport, 12. Other advantages of utilizing strengthened ultra-thin glass of between 0.5mm and 2mm in thickness is that it is extremely light weight, low expansion coefficient, high thermal shock resistance, more durable, stronger in compression and tension, higher scratch resistant, takes up much less space, much easier and less expensive to pack and ship, this glass does not require a significant thickness with thicknesses of 6mm being typical.

13. Moreover, strengthened ultra-thin glass can eliminate the need for a frame to hold the glass in place that has to be attached to a Wall or surfaces for hanging using screws or nails, it can be attached to a Wall or surface using double sided removable tapes or self-adhesive removable strips directly to the back of the glass panel and attached to the said surface causing no damage to those surfaces.

SUMMARY OF THE INVENTION

14. In summary, the invention comprises a process for providing an ultra-thin glass plate of thickness between 0.5mm and 2mm that allows the application of a polymer coating for applying a dye sublimation image to a piece of ultra-thin glass in a commercially acceptable time period. The layered glass article being placed into a flatbed heat press subsequent to receiving a graphic decoration by dye diffusion thermal transfer. The process yields an ultra-thin glass photographic article comprising of an optically clear glass layer and an adjacent synthetic organic polymer in a fast and timely manner.

BRIEF DESCRIPTION OF THE DRAWINGS

15. FIG. 1 is a cross sectional diagram of a coated ultra-thin glass article; ; 16. FIG. 2 is a cross sectional diagram of the coated substrate shown in FIG. 1 while heat and pressure are causing the diffusion of the dye into the polymer coating from the dye sublimation transfer paper; 17. FIG. 3 is a cross sectional diagram of the coated substrate shown in FIG. 1 after the heat and pressure from the press shown in FIG. 2 is released and the dye sublimation image has transferred into the coating.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

18. Glass substrate is typically between 0.1mm and 2mm in thickness and a soda lime float glass standard formulation. A typical composition of this glass is 70-75 wt% 5i02, 12-16 wt% of Na20, and 1019 wt% CaO (Bauccio, 1994; Pfaender, 1996) 20. A flat plate of soda lime glass at the required thickness is cut to the required size, the edges are ground and polished and corners are rounded to ensure any micro cracks are kept to a minimum.

21. The process of flexibility and chemical strengthening of the glass consists of submersing the ultra-thin glass plates for a given period of time of between 8 hours and 24 hours in a bath of molten potassium nitrate salts at between 420 degrees Celsius and 480 degrees Celsius. The Glass parts are immersed in the molten salt solution, potassium ions (electronically charged particles) in the solution migrate into the glass surface, during the submersion cycle, the chemical potassium ions are exchanged with the sodium ions. The larger potassium ions "wedge" their way into the voids in the surface of the glass created when the smaller sodium ions migrate to the special potassium nitrate solution. This ion exchange locks the surface of the glass in a state of compression and the core in compensating tension. The resulting glass is given far greater flexibility and strength.

22. The glass is now strong enough to be used for coating with a polymer to be able to accept a sublimation image and allowing it to be used in a standard heat press used in the sublimation industry.

23. The ultra-thin coated glass can now be imaged by a standard sublimation heat transfer process in under 2 minutes 24. The present invention now provides for an ultra-thin glass article to be imaged with minimal processing time, the ultra-thin glass is stronger more flexible and weighs less, has a small expansion coefficient so it can tolerate the heat and pressure applied by a heat press in the normal process of applying a sublimation image, thus overcoming many obstacles that prior to this have prevented such a product from being produced and marketed in volume. More than one ultra-thin glass article can also be placed into a heat press to increase productivity and multiple images can be processed at the same time saving time and money.

25. While I have shown my invention in one form, it will be obvious to those skilled in the art that it is not so limited but is susceptible and capable of various changes and modifications without departing from the spirit of the invention

Claims

CLAIMS1. A method of making an item of ultra thin flat glass that is strengthened by the method of ion exhange.
2. A method of making an item of ultra thin flat glass according to claim 1 where the glass is coated with a polymer coating to allow a sublimation image to be applied by heat and pressure in a flatbed heat press.
3. An item of ultra thin flat glass where according to preceding claims the image is translucent and clearly visable from one side.
4. An item of ultra thin flat glass where according to preceding claims the image is translucent and can be clearly seen from both sides.