PROCESS FOR IMPROVED GLASS ARTICLE COATING,AND SUCH COATED ARTICLES

Abstract: A method for "hot end" coating of vitreous articles, and particularly glassware such as bottles, with zinc oxide, and mixtures thereof with magnesium oxide from organic and inorganic zinc compounds and mixtures thereof with magnesium compounds. Particularly useful is zinc acetate are applied to the vitreous surface at an elevated temperature, and preferably between about 425`C and 650`C, to pyrolytically decompose the metal compound or compounds to form refractory oxide coatings which are transparent and adherent, and articles coated by such a method.

Description: De script ion Process For Improved Glass Article Coating, and Such " Coated Articles Technical Field The present invention relates generally to improved methods for forming "hot end" coatings for vitreous articles such as glassware, and more particularly to new and improved methods for forming zinc oxide, and mixtures thereof with magnesium oxide, "hot end" coatings upon glassware, and to-articles so coated. Background Art The desirability of forming refractory coatings on vitreous surfaces, such as glass, and particularly upon glassware such as bottles, is. well known. Pristine glass is theoretically an extremely strong substance. However, when, for example, ' glassware is subjected to high speed packing and processing machines and normal use in which glass is caused to rub against glass, scratches, abrasions, and other physical damage rapidly degrades the surface of the glass thereby providing sites for initiation of failure throughout the glass. Also, glass is subject to attack by various atmospheric consitituents, particularly moisture. Accordingly, it has been an accepted practice in the production of glassware to form a refractory, so-called "hot end" coating upon the newly formed glass, usually at or before the annealing lehr while the glassware is at an elevated temperature. After formation of the refractory "hot end" coating, it is conventional practice to thereafter apply a lubricious "cold end" coating at lower temperatures. "Cold end" coatings conventionally include, for instance, waxy polyethylene, fatty acids, beeswax, and other such lubricious compositions either alone or in combination. Neither the "hot end" coating or "cold end" coating is protective, and alone each provides little protection against scratching by a similarly coated vitreous article. The "hot end" coatings, to which the present invention pertains, display particular requirements which distinguish such "hot end" coatings from a number of other coatings previously employed upon glass for various purposes. As an example, thick coatings of tin oxide and magnesia have been applied to, for instance, electrical insulators. Other thick coatings of tin oxide have been applied to provide electrical conduc¬ tivity for defrosting of glass surfaces by employing the tin oxide coating as a resistance element. Semi- transparent, colored coatings have been utilized for decorative purposes and, in some instances, for tinting of glass. "Hot end" coatings have a number of requirements not met by many glass coatings. Typically, such coatings should be non-toxic as a coating, and also are desirably formed from compositions which are not in themselves toxic and which do not form toxic by-products. The coatings formed should not change the appearance of the • glassware, i.e., should be colorless and substantially free of iridescence. Contrary to . the purpose of certain other glass coatings, "hot end" coatings should have high electrical resistance to avoid galvanic action with container caps and moisture which leads to unsightly cap corrosion and/or increased torque requirements. Since glassware is formed at high rates, coatings must be conveniently applied and utilize relatively economical solvents and compounds. Further, "hot end" coatings must be resistant to normal handling and processing, and must tenaciously adhere to the glass and provide a suitable base for lubricious "cold end" coating. Thus, it will be recognized that "hot end" coatings for glassware are a well recognized group of materials o;.? having characteristics and requirements distinct from other glass coatings. Currently, "hot end" coatings are generally tin oxide or titanium oxide, formed from vapors of anhydrous tin or titanium tetrachloride or from aqueous solutions of such compounds. However, previously "hot end" coatings of tin oxide, titanium oxide, magnesium oxide or zirconium oxide have also been formed from organic compounds applied in or from organic solutions. A number of prior art discussions exist concerning the various coatings. For instance, U.S. Letters Patent 2,165,819, issued July 11, 1939, discloses an electrical insulator of magnesium titanate suitable for formation on ceramic substances such as condensors. Magnesium titanate is disclosed as being suitable for a narrow, and quite specific coating purpose, but does not correlate with the requirements of a "hot end" coating. U.S. Letters Patent.3,323,889, issued June 6, 1967, discloses a coating system for the purposes of the instant invention, but involves the use of titanium oxide .as a "hot end" coating applied from an organic solvent solution in conjunction with relatively conven¬ tional "cold end" coatings. Organic solvents are expensive, often flammable, i.e., as is tetraisopropyl alcohol and cause objectionable pollution of the atmos¬ phere. However, U.S. Letters Patent 3,323,889 is pertinent in setting forth many of the requirements of a "hot end" coating. U.S. Letters Patent 3,450,574, issued June 17, 1969, is concerned with the preparation of a magnesia coating on refractory bodies. Preferable, the patent teaches the formation of a thin film of metal under reducing conditions and thereafter providing oxidizing conditions to form the oxide. Sintering techniques are O PI also disclosed. Clearly this patent does not pertain to "hot end" coatings contemplated by * the instant invention. U.S. Letters Patent 3,516,811, issued June 23, 1970, primarily discloses apparatus for applying "hot end" coatings in laminar flow conditions, but also contains a fairly comprehensive listing of various prior art patents dealing with "hot end" and "cold end" coatings. Typical of the hot end coatings discussed by U.S. Letters Patent 3,516,811 is that of U.S. Letters Patent 3,561,940, issued February 9, 1971, which concerns the formation of tin oxide coatings by the pyrolytic composition of anhydrous stannic tetrachloride vapors in a moisture-free carrier gas. While tin oxide is a desirable and workable "hot end" coating, the by¬ products of the pyrolytic decomposition include, hydro¬ chloric acid (upon hydrolysis with atmospheric moisture) which presents serious problems with regard to attack of surrounding equipment and pollution of the atmos¬ phere. Such installations may require expensive scrubbing equipment to remove the unused stannic tetra- chloride and hydrochloric acid from the exhaust gases. U.S. Letters Patent 3,694,299, issued September 26, 1972, discloses a means for fusing glass sheets together utilizing an organo-metallic film forming solution in which the metallic constituent may include magnesium. However, the solution utilizes volatile and combustible solvents as well as resins which would be entirely inappropriate for use in a "hot end" coating composition for the reasons discussed above. U.S. Letters Patent 3,711,322, issued January 16, 1973, discloses organic solvent based compositions utilizing two metal compounds, one of which may be a magnesium compound such as magnesium acetate, to form semi-transparent, colored metal oxide coatings. For. numerous reasons including transparency, color, organic solvents, etc., such coatings would not be useful as "hot end" coatings. U.S. Letters Patent 3,847,583, issued November 12, 1974, similarly discloses the use of two metal compounds dissolved in an organic solvent to form coatings. Titanium oxide and, it is believed, tin oxide, are discussed, and specific mention* is made that alkali and alkali earth oxides are not operable to form pyro- lytically induced oxide coatings. U.S. Letters Patent 3,926,103, issued December 16, 1975, discloses a recovery system for spray solutions of tin compounds. Finally, U.S. Letters Patent 3,984,591, issued October 5, 1976, discloses the formation of metallic oxide coatings from metallic salts utilizing, as a critical feature of the invention, aprotic solvents of specified dipolar moments which would be inappropriate for "hot end" coatings. Mention is made of spraying aqueous solutions, but such coatings are characterized as being readily ' removed in the form of dust by passing a finger over the coating. "Protective" coatings are _. taught to be tin oxide, zirconium oxide and titanium oxide. For other purposes such as coating glass ' fibers, applications of zinc stearate in powder form is practiced as taught in U.S. Letters Patent 4,191,585,. issued March 4, 1980. Thus, on the basis of the above prior art, the only workable "hot end" coatings are those involving pyrolytic decomposition from objectionable organic solvents or from halides. In both cases, objectionable by-products in the form of exhaust fumes are presented. The better, more economical coatings involve pyrolytic decomposition of stannic tetrachloride with the result¬ ing formation of hydrochloric acid. Disclosure of Invention The present invention, which provides a heretofore unrecognized improvement over previous methods for forming "hot end" coatings on glassware, involves pyrolytic decomposition of zinc compounds and mixtures thereof which, directly or indirectly, form primarily zinc oxide coatings upon glassware heated above about 425°C, and preferably between 425-650°C. Particularly, zinc acetate provides high quality coatings with innocuous by-products, though other zinc compounds, and magnesium compounds admixed therewith have also been found to be operable. _ According to the present invention, "hot end" coatings of zinc oxide are formed on vitreous substances such as glassware by applying zinc compounds having specific properties, typically in aqueous solutions, to glassware heated to an elevated temperature, i-e», above 400 β C to 450 o C, and preferably below 650°C. Typically, such surfaces are not heated above about 700°C, but in specific instances may be heated to higher temperatures while providing at least operable results. " Many of the advantages of the instant invention accrue from the use of aqueous rather than organic solutions of the zinc compounds. Essentially, the compounds should be sufficiently water soluble zinc and magnesium compounds to provide reasonable coating concentrations when in solution. The compounds may be dissolved in a water carrier sprayed upon hot glassware, preferably in the form of a mist or fine spray of the aqueous solution. It is also important that the compounds decompose to zinc oxide at the temperatures existing on the surface of the glassware and, preferably, after initially melting of the zinc compound particles formed such as by evaporation. Fine particles may of course be applied directly, i.e., as a powder, rather than produced from a solution. O As used herein, aqueous solutions are those including at least about fifty percent water. Various additives such as surfactants may be included, and particularly short chain alcohols such as ethanol and propanol may be included in substantial amounts. While the mechanism of the instant invention is not entirely understood, it is postulated that the zinc compounds are first deposited as a solid particle upon the heated glassware, as water is evaporated from the solution. The compounds initially melt and then pyrolytically decompose to form zinc oxide. Accordingly, if the original zinc compound, or any intermediate zinc compound other than zinc oxide formed during the course of pyrolytic decomposition, is stable at the temperature involved, satisfactory results will not be obtained. Examples of zinc compounds which meet the above criteria as usable "hot end" coatings include zinc acetate, zinc formate, zinc nitrate, zinc perchlorate, and zinc chloride. Small amounts of zinc fluosilicate may be added to the above compounds and mixtures thereof. Sulfur containing compounds generally are not decomposable to zinc oxide under the available tempera¬ tures. Coating clearity from solution appears to be a function of the solubility of the compound. More soluble zinc compounds, above, are believed to form small particles of the compound upon the glassware which particles are believed to then melt into a smooth continuous layer of the compound, and then pyrolytically decompose into zinc oxide. Water insoluble or marginally soluble zinc compounds do not usually yield the desired results, possibly because of the formation of solid particles in the presence of substantial quantities of water and which do not melt into a smooth layer prior to pyrolytic decomposition. Other mechanisms, such as ion exchange, may be involved. However, direct application of fine particles which then melt and decompose is also workable. Of the zinc compounds which satisfy the basic criteria, i.e.,. high water, solubility, melting point below the general surface temperature of glass, and pyrolytic decomposition into zinc oxide at the surface temperature of the glass, zinc acetate is a particularly preferred composition having properties significantly superior to those of other of the operable zinc com- pounds. Zinc chloride, zinc nitrate, and zinc perchlorate, produce acceptable coating, but with usually objectionable by-products. The resulting zinc oxide "hot end" coatings in accord with the instant invention should, of course, be thick enough to afford coverage to the protected vitreous surface, such as glassware. However, in most instances, the coating should not be thicker than about one/half wavelength of light to which it is typically exposed, i.e., about ne quarter micron, to avoid wave interference within the coating leading to iridesence. In some instances, coatings may be thicker without otherwise degrading the results. Iridesence, at times, may be considered a desirable appearance. Also, thicker coatings tend to be more electrically conductive. As a rule, the coating thickness may be easily controlled by regulating the solution flowrate and/or the exposure time of the heated glassware to a given concentration of the zinc compound. The zinc oxide coatings of the instant invention are not homogeneous layers, but rather, include other compounds particularly at the glass interface and the outer surface. However, the layers are predominantly zinc oxide. As discussed above, the zinc compound should be applied to a surface at a temperature of at least about OM ,,_ Vv'IF 400°C, preferably between 425°C and 650°C, though higher temperatures are suitable for coating purposes. In most instances though, the vitreous surface may be adversely affected by higher temperatures, though certain vitreous surfaces, such as ceramic, may be heated to quite elevated temperatures. Each compound suitable for forming zinc oxide coatings in accord with the instant invention of course displays differing melting points and pyrolytic decomposition points. Accordingly, optimum temperatures may vary somewhat from compound to compound, though the above specified temperatures are generally operable. For instance, zinc acetate is preferably applied between 425°C and 650°C, though fair results may be obtained outside of this range. The concentration of the zinc compound compound in an aqueous solution is not critical. Of course,. ore dilute solutions require evaporation of greater quantities of water and accordingly cool the glassware surface more. However, limited cooling often enhances results. As a rule, between about 10% to 50% by weight of zinc compound to weight of solution has been found to be a desirable operating range, though not a critical range. * Preferably about the midpoint of this range is employed. Solutions of mixed compounds, or those including alcohols, are often more viscous. It should be noted that the solubility of the zinc compound in water based solvents is an independent • consideration from that of the actual concentration of the magnesium compounds in solution when applied to vitreous surfaces. Thus, compounds which marginally dissolve at the above-specified concentration are not necessarily desirable coating compounds. As the water evaporates, solid particles of the zinc are of course formed on the vitreous surface. This result can be prematurely accomplished in near saturated solutions of zinc compounds. Accordingly, while not firmly es¬ tablished, it is believed that the more highly soluble zinc compounds operable in the instant invention do not form solid particles until but small amounts of water remain thereby minimizing the concurrent existance of solid matter and solution and leading to melting of the solid particles to form an initial coating. This may be avoided by direct application of fine particles to the heated glassware. It is contemplated that the zinc oxide coatings formed in accordance with the instant invention will be further coated with lubricious "cold end" coatings as are well known in the art. The oxide coatings per se are not lubricious and thus not protective. In com- bination with "cold end" coating outstanding protection is afforded. Generally, this is accomplished by spraying the lubricious coatings, usually as aqueous solutions, onto the vitreous surfaces after, in the case of glassware, annealing is substantially complete. Vapors of organic " lubricious materials may also be employed to accomplish the coating. "Cold end" coatings are well known in the art. Typically such coatings include one or more lubricious constituent, such as waxy polyolefins, and particularly polyethylene having a molecular weight between 1000 and 2000, fatty acids such as oleic, palmitic, stearic, lauric, or mixtures thereof, alkali metal salts of fatty acids and poly- vinyl alcohol. Such "cold end" coatings are well known in the art and are applicable to the zinc oxide coatings in accord with the instant invention. It appears that the zinc oxide coatings of the instant invention form chemical bonds with many "cold end" coatings and particularly with the fatty acids, while tin oxide forms only physical bonds. A more detailed appreciation of the invention will be gained from the following example. Example A substantial number of newly formed glassware articles from an eight section double gob IS machine operating at a production rate of 166 bottles per minute were coated and tested. Various groups of otherwise identical bottles were coated only with "hot end" coatings according to the instant invention, only with "cold end" coatings, left -uncoated and in com¬ binations thereof. A first "hot end" coating of an aqueous solution of zinc acetate, including by weight, 13.4% zinc acetate, 0.87% glacial acetic acid and the remainder water, with 5 milliliters of Triton XI00 surfactant added per gallon, was employed. The zinc acetate solution was sprayed on freshly formed bottles at the rate of 2.25 gallons per hour through 4 nozzles in opposed pairs. The glassware was then annealed in a conventional manner and a commercial "cold end" coating, i.e. Owens Illinois Duracoat, was applied to selected samples of the glassware articles. Certain of the glassware articles were removed at the end of the lehr prior to testing and case packing, while others were subjected to automatic testing and case packing. The ware was tested utilizing a number of con¬ ventional commercial tests. The CTU determines the thickness of the "hot end" coating as a function of the index of refraction. Thereafter slip tests, in which the angle at which the static coefficient of friction is overcome by gravity by utilizing a tilting table were conducted. Tests were carried out according to industry standards. Scratch resistance was similarly determined in accord with industry standards utilizing a commercial scratch resistant tester. These tests measure the scratch resistance under load of the ware with the industry's standards calling for a minimum of 25 pounds resistance when wet. Burst tests were run in which the bottle was subjected to internal hydrostatic pressure until failure. The results are tabulated in the Tables below. TABLE 1 Slip Slip Scratch Scratch CTU ;Dry ' ' ' ;Wef - :Dry * * :Wet PrLP- 2-5? 40' 42" 5 lbs 5 lbs 3 Ave. Abused P:LP P/D:LP 11 < 10 lbs 5 lbs P/D:CP 12 ( 15 ' 20 lbs 5 lbs Zn:LP 25-40? 41 « 38 < 5 lbs 10 lbs 31 Ave. Zn/D:LP 40-40? 11 < 70+lbs 70+lbs 40 Ave. Zn/D:CP 25-45? 13° 10° 70+lbs 70+lbs 36 Ave. P = Pristine LP = Lehr Packed CP = Case Packed D - Cold End Coated Zn = Zinc Oxide Coating TABLE 2 IT S * .D. Low N 200 P:LP 60 321 121 112 9/60= 0.15 Abused 48 283 129 117 20/48= P:LP 0.42 P/D:LP 85 439 109 211 0/85= 0.00 P/D:CP 94 367 86 168 3/94= 0.03 Zn:LP 91 363 129 107 9/91= 0.10 Zn/D:LP 94 416 103 179 1/94= 0.01 Zn/D:CP 93 407 98 193 1/93= 0.01 P = Pristine LP = Lehr Packed CP = Case Packed D = Cold End Coated Zn = Zinc Oxide Coating N = Sample Number B = Average Burst Pressure in psi S.D. = Standard Deviation in psi LOW = Lowest Burst Pressure in psi N 200 = Number Failing Below 200 psi -"^TO EA " ^ O PI From the results it will be apparent that "cold end" coated glassware without "hot end" coatings are deficient in the scratch test? and that glassware without any coating at all are also subject to seizure and scratching. Similarly, glassware having only "hot end" coatings are subject to seizure i.e. low lubricity, and to scratching. However, the glassware coated with the zinc oxide plus the "cold end" coating all display excellent lubricity as shown by the slip test, out- standing resistance to scratching, as well as an enhanced burst pressure i.e. relatively high. It will be recognized that lehr packed glassware, being less abused and less subject to incipient failure cracking, would be expected to display a higher burst pressure than, for instance, case packed ware which is jostled by automatic inspection equipment and packing equipment. Thus while lehr packed pristine glass having "cold end" coating displays a favorable average burst pressure, similar pristine "cold end" coated glassware which is case packed shows a significant deterioration in the average burst pressure while case packed "hot end" and cold end" coated glassware, i.e. , zinc oxide coated, show superior burst pressure. Numerous other tests were conducted to determine the.characteristics of the "hot end" coating method of the instant invention, and of the resulting "hot end" coating. For instance, newly formed glassware was coated with a 9 to 1 ratio by volume mixture of zinc acetate and magnesium acetate, otherwise substantially as described above. The glassware was purposely coated on the finished portion thereof filled with Tab beverage. After storage, tests using uncoated ware as a standard, produced no indication of degraded torque removal or corrosion at the cap. In both cases, the preformance of the zinc oxide coatings were superior to that of tin oxide and titanium oxide. Comparisons of the zinc oxide coatings of the instant invention, relative to the conventional tin oxide coating, were made with regard to adhesion of the "cold end" coatings thereto when exposed * to hot water and caustic wash treatments. While such tests are not industry standards, on the basis of the test runs and discussions with those expert in the art, it was concluded that tin oxide coatings provide good results with waxy polyethylene coatings, but poor results, particularly in caustic solution at elevated temperatures, with fatty acids. On the other hand, the zinc oxide coatings of the instant invention appear to be somewhat less effective than tin oxide when utilized with waxy polyethylene lubricious coatings, but greatly superior thereto when utilized with fatty acid materials. On the basis of the observations, it is then postulated that the "hot end" coatings of the instant invention form a chemical bond with the fatty acid "cold end", thereby substantially enhancing the tenacity of the two coatings to the glass article. With this in mind, one skilled in the art may tailor "cold end" coatings to take advantage of this propensity for chemical bonding rather than, as has been done in the above testing, merely utilizing lubricious coatings which were tailored for tin oxide "hot end" coatings. ' Other tests indicate that mixtures of appropriate zinc and magnesium compounds, for instance, in an aqueous solution provide excellent results. Of the mixed compounds, a particularly useful ratio is that in which 85% to 90% by weight of the coating compound is zinc acetate and 10% to 15% by weight is magnesium acetate, though mixtures throughout the full range provide outstanding results. Coatings solution vis¬ cosity, at given concentrations of coating compound in aqueous solvent, are affected by the ratios. However, since coating has not been optimized with regard to ι-:?ι W ' lcQ _. application, other than to preferably utilize opposed atomizing spray nozzles for the solution on either side of a belt carrying the glass articles, the significance of viscosity is not great. Also, while, for purposes of the instant invention, aqueous solutions are defined as having at least 50% water in the solvent, improved results have been obtained by including amounts of up to 50% of short chain, i.e., one to four carbon atoms, alcohols. It has been inferred that the cooling afforded by the alcohol may somewhat improve the resulting "hot end" coating, but at the cost of a much more expensive solvent than water. Thus, lesser amounts of alcohols, i.e., on the order of 15% of the solvent, appear to be preferable when balancing the various considerations. In summary, it has been found that zinc compounds and mixtures of zinc compounds and magnesium compounds may be employed to form so-called "hot end" refractory coatings on glass articles including ceramic materials. These refractory coatings in themselves are not pro¬ tective of, for instance, glassware but afford great protection when utilized in combination with so-call "cold end" coatings, such as organic lubricious coatings. Heretofore, only Magnesium oxide, tin oxide and titanium oxide have been utilized as "hot end" coatings. Thus it was surprising to find that zinc oxide coatings, and mixtures thereof with magnesium oxide, afford results which in most significant areas are superior to those of tin oxide. Though only several specific examples and embodi¬ ments of the present invention have been presented in detail, those skilled in the art will recognize numerous changes and modifications within the scope of the invention. Such changes may be made without parting from the scope of the invention, as defined by the following claims.

Claims: Claims 1. A method for forming protective coatings upon glass articles comprising: positioning a glass article heated to an elevated temperature within a coating location? applying a coating compound selected from the group consisting of zinc compounds and mixtures thereof with magnesium compounds upon the surface of the heated glass article? pyrolytically decomposing the remaining coating compound at the surface of the glass article to form a continuous, adherent and substantially transparent coating of the coating compound metal oxide upon the surface of the glass article? cooling the glass article and metal oxide coating thereon? and _ - applying a second, lubricious ' coating thereto at a lower temperature. 2. A method for coating glass articles as set forth in Claim 1 in which the surface of the glass article is at a temperature above 400°C. 3. A method for coa.ting glass articles as set forth in Claim 1 in which the surface of the glass article is at a temperature between about 425°C and 650°C. 4. A method for coating glass articles as set forth in Claim 1 in which the coating compound is applied in an aqueous solution and is melted after the water is substantially evaporated to form a coating of the solution compound upon the glass article surface, and in which the coating is thereafter pyrolyzed to form the coating of metal oxide. OMPI 5. A method for coating glass articles as set forth in Claim 4 in which the dissolved coating compound comprises between about 10% by weight and 50% by weight of the aqueous solution. 6. A method for coating glass articles as set forth in Claim 1 in which the coating compound is highly soluble in water, has a melting point below the surface temperature of the glass articles, and a pyrolytic decomposition point below the surface tempera- ture of the glass articles but above the melting point of the coating compound. 7. A method for coating glass articles as set forth in Claim 6 in which the coating compound is selected from the group consisting of zinc acetate, zinc formate, zinc nitrate, zinc perchlorate and* zinc chloride. 8. A method for coating glass articles as set forth in Claim 7 in which the coating •compound is zinc acetate. 9. A method for coating glass articles as set forth in Claim 8 in which the zinc acetate is applied as a solution containing between 10% and 50% by weight of magnesium acetate relative to the solvent. 10. A method for coating glass articles as set forth in Claim 8 in which the surface of the glass articles are at a temperature above about 400°C. 11. A method for coating glass articles as set forth in Claim 8 in which the surface of the glass articles are at a temperature between about 425°C and 650°C. C 12. A method for coating glass- articles as set forth in Claim 1 in which the metal oxide coating is between about .1 micron and 1 micron thick. 13. A method for coating glass surfaces as set forth in Claim 1 in which the lubricious coating includes at least one compound selected from the group consisting of waxy polylefins, beeswax, fatty acids, alkali metal salts of fatty acids, and polyvinyl alcohols. 14. A method for forming protective coatings on glass comprising: applying a coating compound of zinc acetate onto the surface of glass at an elevated temperature? melting the zinc acetate coating compound onto the surface of the glass? and pyrolytically decomposing the zinc acetate at the surface of the glass to form a continuous, transparent film of zinc oxide which tenaciously adheres to the surface of the glass. 15. A method for ** forming protective coatings on - glass comprising: applying a mixture of magnesium acetate and zinc acetate onto the surface of glass at an elevated temperature? and pyrolytically decomposing the magnesium acetate and zinc acetate at the surface of the glass to form a . continuous, transparent film of magnesium oxide and zinc oxide which tenaciously adheres to the surface of the glass. 16. A glass article having protective and lubricious coatings thereon, said articles comprising: a glass surface? a metal oxide coating selected from the group 5 consisting of transparent zinc oxide and mixtures of zinc oxide and magnesium oxide adhered directly to the surface? and a lubricious coating of an " organic compound adhered to the metal oxide. 10 17. A coated vitreous surface as set forth in Claim 16 in which the lubricious coating includes at least one constituent selected from the group con¬ sisting of waxy polyolefins, beeswax, fatty acids, alkali metal salts of fatty acids, and polyvinyl 15 alcohols. 18. A coated vitreous surface as set forth in Claim 16 in which the metal oxide coating is not greater than one quarter micron thick. 19. Glassware having protective coatings thereon, 20. the glassware comprising: a glass surface? a transparent, continuous, thin coating of .zinc oxide adhered to the glass surface? and a lubricious coating adhered to the zinc oxide 25 coating. 20. Coated glassware as set forth in Claim 19 in which the lubricious coating includes at least one constituent selected from the group consisting of waxy polyolefins, beeswax, fatty acids, alkali metal salts 30 of fatty acids and polyvinyl alcohols. O P 21. Coated glassware as set forth in Claim 19 in which the zinc oxide coating is not greater than one quarter micron thick. 22. Glassware having protective coatings thereon, the glassware comprising: a glass surface? a transparent, continuous, thin coating of zinc oxide and magnesium oxide adhered to the glass surface? and a lubricious coating adhered to the zinc oxide and magnesium oxide coating. 23. Coated glassware as set forth in Claim 22 in which the lubricious coating includes at least one constituent selected from the group consisting ,of waxy polyolefins, beeswax, fatty acids, alkali metal salts of fatty acids and polyvinyl alcohols. 24. Coated glass ware as set forth in Claim 22 in which the zinc oxide and the magnesium oxide coating is not greater than one quarter micron thick.

Inventors: FOGELBERG C, ROMIG J
Applicants: LAM PARTNERSHIP
Application year: 1981
Main classification: C03C17
IPC codes: C03C17