SPUTTER-COATED THIN GLASS SHEETING IN ROLL

FORM AND METHOD FOR CONTINUOUS PRODUCTION THEREOF

Technical Field This invention relates to a method for the continuous production of large uninterrupted areas of sputter-coated glass sheeting in roll form and to rolls which comprise glass sheeting having on at least a portion of one surface of the sheeting, a coating of sputter-deposited material such as metals, semi-conductors, metal alloys, metal oxides, and mixtures thereof, and one or more layers of interleafing material which is non-abrasive to glass, positioned between and separating the surfaces of the glass sheeting. In one form of the invention the glass has raised or beaded edges, and the interleafing material separates the surfaces, including the beaded edges, of the glass.

Background Art

Methods and apparatus for the continuous production of sputter-coated glass products such as separate single sheets of glass are known. Thus, such a method and apparatus is disclosed in U.S. Patent No. 3,904,506 issued September 9, 1975. Other patents referring to and disclosing the sputter-coating of glass sheets are, for example, 4,009,090 issued February 22, 1977, U.S. Patent No. 3,945,911 issued March 23, 1976. The foregoing patents, representative of the prior art, are all directed to the sputter-coating of sheets of glass of finite length for use as architectural glass, vehicle windows, oven windows, window glass, plate glass, and float glass.

U.S. Patent No. 4,322,276, issued March 30, 1982 to Nathan K. Meckel and Benjamin B. Meckel, is directed in a preferred embodiment, to the production of sputter-coated plastic material such as polyester sheeting by a procedure wherein the plastic sheeting is unwound from a roll or spool thereof, the web of sheeting conveyed through a sputtering chamber for deposition thereon of a coating of a variety of metals to result in an inhomogeneous lamination. Substrates such as glass or crystal can also be subjected to the sputtering techniques which are disclosed, to produce an inhomogeneous thin film laminate thereon.

Disclosure of the Invention

My invention is directed to a method for continuously producing rolls of thin sputter-coated glass which comprises conveying a web of thin glass, from a take-off spool, the web in one form of the invention, having raised edge portions or beads, within an evacuated chamber while sputter-depositing on a surface of the moving web a deposit of metal, semi-conductor, metal alloy, metal oxide or mixtures thereof, onto a take-up spool, the web on the take-off and take-up spools being protected from glass-to-glass contact.

The glass web on the take-off spool has a web of a non-abrasive material, such, as a film of Mylar, or any other non-abrasive (to glass) material, interposed between the layers of glass on the spool, and is removed from its inter¬ posed position, as the roll is unwound. And another web of non-abrasive material is interposed between the layers of sputtered glass, as the glass web, following the sputtering step, is wound up on the take-up spool. The web of non- abrasive material is of a thickness and width such that it

separates the glass layers, so that there is no glass-to- glass contact while the glass web is wound up on the spool, and, if the web has raised edges, maintains the raised edges thereof in a free floating posture, i.e. the said edges not touching the raised edges of the glass layers above or below them on the roll. A second web may be much thinner than the other web, and of a width such that it extends beyond the raised edging of the glass web.

The thin raised-edge glass sheeting or web, is sufficiently flexible to be wound onto an appropriately dimensioned take-off spool, the diameter of the spool being sufficiently large to permit winding the web onto it, and protected from contacting the upper and lower surfaces of the glass layers, above and below, as the web is wound onto the spool, by interposing between the glass surfaces, as above noted-, a layer of material which is non-abrasive to glass, such as a polymeric plastic material typified by polyester or polyethelyne film or the like. Thin glass sheeting having a thickness, for example, of 1 to 15 mils, will fracture almost immediately if it is rolled up. While the reason for this is not entirely understood, it appears that even extremely small amounts of materials of small particle size, such as dirt, sand, glass fragments or similar materials, are sufficiently abrasive to initiate fractures in the glass, especially when the glass is under tension as when wound around the core of a spool. Insofar as applicant is aware, the prior art has not succeeded in producing rolls of sputter-coated thin glass sheeting, nor has the prior art disclosed production of such rolls by any procedure which includes forming a -roll of a continuous web

of glass such that there is no actual contact between the layers of glass on the roll, unwinding the roll, conveying the resulting sheeting or web through a magnetron sputtering environment whereby to deposit on at least one surface of the glass web a layer of metal, or alloy or metal oxide, and then winding up the resulting web on a roll such that there is no contact between any portion of the layered glass surfaces comprising the resulting roll. The unwinding of glass web, and protective web, or webs, from the take-off roll, sputter-deposition, and winding up of sputter- deposited glass web and protective web, or webs, takes place in a closed vacuum chamber containing a planar magnetron or magnetrons, magnetron target materials, which may include metals, semi-conductors, metal alloys, metal oxides, or mixtures thereof, means for introducing oxygen into the chamber whereby metal oxides can be deposited by reactive sputtering. Various forms of sputtering methods, apparatus, and procedures are discussed, for example, in U.S. Patent No. 4,426,275 issued January 17, 1984, included herein by reference, as well as other methods, apparatus, and pro¬ cedures well-known in the art.

Brief Description of the Drawings

Figure 1 is a diagramatic or schematic side view of an embodiment of the method of my invention.

Figure 2 is a view in cross-section of layers on the take-up and take-off rolls.

Figure 3 is another view of a differently layered arrangement and relationships between the glass sheeting and interposed protective layer of non-abrasive (to glass) material.

Best Mode for Carrying Out the Invention

Referring to Figure 1 therein is illustrated a closed chamber 11 equipped with appropriate ingress and egress means (not shown), adapted so that a high vacuum can be produced therein by use of a vacuum pump 13, and pump means 14 for injecting a desired gas into the chamber. Idler rollers 21 and 22 support the glass sheeting as it moves from take-off spool 15 to take up spool 23. As the glass sheeting 19 is would up on take-up spool 23, having core 24, protective webs 23a and 23b are fed onto the spool 23 from spools 27 and 28. It is to be understood that one or more layers of the protective web material can be interposed between the glass surfaces, as desired. The plastic film 18 in protective webs 23a and 23b are formed, as previously noted, of Mylar —a trademark for a polyester of glycol and terephthalic acid, or other non-abrasive (to glass) plastic film. I have found embossed polyester film available from ICI Americas, Inc. of Wilmington, Delaware, U.S.A., under the tradename of ICI Melinex 470-200; ICI Melinex 377-200; ICI Melinex 329; and especially Melinex CIE, a film exhibiting a "cracked ice" embossed pattern particularly useful.

Positioned under the traveling web 19 is a cathode 29 having an appropriate target 31 maintained at substan¬ tially the same potential as cathode 29.

The raised edgings 32 and 33 shown in Figures 2 and 3 which are on opposite sides of the glass sheeting 19, ride on idler rollers 21 and 22, and similar rollers located on the opposite side of the glass sheeting 19, as the glass sheeting is would up on spool 23, with the edgings 32 and 33 resting on the interposed protective films 23a and 23b.

In one form of the invention, the glass sheeting 19 is 5.5 mils thick with the edgings, or beads being 16 mils in thickness. As shown in Figure 2, the thickness of the separating layer 23a is such that the center of glass sheeting 19 is supported, leaving the beaded edges 32 and 33 substantially free floating. The width of that center flat section of the sheeting 19 which is 5.5 mils thick is 13 1/4 inches, with the overall width being about 16 1/2 inches. The spools 15 and 23, which are flanged, are preferably made of a low out-gassing material such as styrene, acrylic or the like, and have core diameters of 18 inches. The purpose of the flanged take-up and take-off spools is to prevent edge damage to the glass sheeting, since any edge damage will get propagated across the sheeting. The clearance between the flanges of spools 15 and 23 and edge of sheet 19 is approximately 1/4 inch.

The target 31 of the cathode 29 may be formed of any metal, semi-conductor, metal alloys, metal oxide, mixtures thereof or other suitable material, as those skilled in the art will understand.

My invention results in greatly reducing the cost and complexity of sputter-coating glass, and allows production of very large, uninterrupted sputtered surfaces, a matter of great importance in the production of photovoltaic panels, flat panel information displays, window heaters, and thermal blankets for speedσraft. Other uses of the sputtered glass product of my invention lie in, e.g. electrodes for liquid crystal display; high performance reflectors where the reflector is adjacent to a lamp which reaches a high temperature, precluding use of plastics; curved reflectors;

adhesive-backed products, wherein the adhesive may be ultra-violet light curable; products for automotive windshield heating; photovoltaic cells; carriers for

* graphics; components for optical glasing, e.g. poly- 5 carbonate glazing with a layer of my sputtered glass applied thereto for abrasion resistance; laser optical discs, rear view mirrors for cars; photomasks for reproduction of integrated circuits; and microwave heater windows.

While a preferred embodiment of the present invention 10 has been described herein, many other modifications of the above invention may be devised and used and it is not intended to hereby limit it to the embodiment shown or described. And the terms used in describing ray invention are to be understood in their descriptive sense and not 15. contrued as words of limitation. The terms web, webbing, and sheeting are used interchangeably herein, as are edges, edging, beads, and beading.