Two-layer protective coating system for LCD glass

Abstract

Two-layer protective coating system for glass surfaces is disclosed. The base coating comprises at least one polysaccharide, and the top coating has a lower solubility in water than the base coating. The coating system provides good protection against contaminants and glass chips, good removability in mild cleaning condition, and extra water resistance during process steps where water is used as a cooling agent.

1 - 58 . (canceled)  
     
     
         59 . An article of manufacture comprising: 
 (a) a glass sheet having at least one substantially flat surface;    (b) a first protective coating on the substantially flat surface comprising at least one polysaccharide, the coating having a thickness of at least 0.01 μm; and    (c) a second protective coating over the first protective coating;    wherein 
 (i) the protective coatings protect the surface from ambient contaminants, contaminants produced during the processing of the glass and/or scratching;  
 (ii) the second protective coating is less soluble in water than the first protective coating; and  
 (iii) the protective coatings can be removed through application of an aqueous cleaning composition to result in a substantially clean surface.  
   
     
     
         60 . An article in accordance with  claim 59 , wherein the glass surface has a water contact angle of equal to or less than 8° after the protective coating is sufficiently removed by a cleaning composition.  
     
     
         61 . An article in accordance with  claim 60 , wherein the glass surface has a Rms surface roughness less than or equal to 0.40 nm as measured by atomic force microscopy.  
     
     
         62 . An article in accordance with  claim 59 , wherein the at least one polysaccharide comprises straight chain polysaccharide molecules and/or branched polysaccharide molecules.  
     
     
         63 . An article in accordance with  claim 59 , wherein the at least one polysaccharide comprises at least one starch.  
     
     
         64 . An article in accordance with  claim 63 , wherein the at least one starch comprises straight chain starch molecules and/or branched starch molecules.  
     
     
         65 . An article in accordance with  claim 59 , wherein the first protective coating comprises a platicizer.  
     
     
         66 . An article in accordance with  claim 59 , wherein the first protective coating comprises a biocide.  
     
     
         67 . An article in accordance with  claim 59 , wherein the first protective coating has a thickness of less than 50 μm.  
     
     
         68 . An article in accordance with  claim 59 , wherein the second protective coating comprises a continuous polymer film.  
     
     
         69 . An article in accordance with  claim 68 , wherein the second protective coating has a thickness of at least 0.01 μm.  
     
     
         70 . An article in accordance with  claim 69 , wherein the second protective coating has a thickness of less than 100 μm.  
     
     
         71 . An article in accordance with  claim 70 , wherein the second protective coating has a thickness of less than 50 μm.  
     
     
         72 . An article in accordance with  claim 59 , wherein the second protective coating comprises at least one polymeric acid.  
     
     
         73 . An article in accordance with  claim 72 , wherein the polymer acid is selected from the group consisting of (i) homopolymers and copolymers of carboxylic acid, phenols and acid anhydrides, salts and partial salts thereof, and (ii) mixtures and other combinations of the polymers.  
     
     
         74 . An article in accordance with  claim 73 , wherein the at least one polymeric acid is selected from the group consisting of (i) homopolymers and copolymers of acrylic acid, methacrylic acid, maleic acid and their anhydrides, salts and partial salts thereof, and (ii) mixtures and other combinations of the polymers.  
     
     
         75 . An article in accordance with  claim 59 , wherein the second protective coating comprises polyvinyl alcohol.  
     
     
         76 . An article in accordance with  claim 59 , wherein the second protective coating comprises hydrophobically modified and/or insolubilized polysaccharide.  
     
     
         77 . An article in accordance with  claim 76 , wherein the hydrophobically modified or insolubilized polysaccharide is a polysaccharide modified by (i) glyoxal; (ii) octenyl succinic anhydride; (iii) at least one water-insoluble resin; (iv) at least one water-repellent additives; (v) at least one latex dispersion; or (vi) any mixture of at least two of (i), (ii), (iii), (iv) and (v).  
     
     
         78 . An article in accordance with  claim 76 , wherein the hydrophobically modified and/or insolubilized polysaccharide is selected from glyoxal-crosslinked polysaccharide, octenyl succinic anhydride modified polysaccharide and mixtures thereof.  
     
     
         79 . An article in accordance with  claim 76 , wherein the hydrophobically modified and/or insolubilized polysaccharide comprises hydrophobically modified or insolubilized starch.  
     
     
         80 . An article in accordance with  claim 79 , wherein hydrophobically modified or insolubilized starch is a starch modified by (i) glyoxal; (ii) octenyl succinic anhydride; (iii) at least one water-insoluble resin; (iv) at least one water-repellent additives; (v) at least one latex dispersion; or (vi) any mixture of at least two of (i), (ii), (iii), (iv) and (v).  
     
     
         81 . An article in accordance with  claim 79 , wherein the hydrophobically modified and/or insolubilized starch is selected from glyoxal-crosslinked starch, octenyl succinic anhydride modified starch and mixtures thereof.  
     
     
         82 . An article in accordance with  claim 77 , wherein: 
 the at least one water-insoluble resin is selected from copolymers of unsaturated carboxylic acids with styrene, ethylene, alkyl vinyl ethers and alkenyl fatty acid esters;    the at least one water-repellent additive is selected from alkenyl succinic anhydride, alkyl ketene dimer, and stearylated melamine; and    the at least one latex dispersion is selected from polystyrene butadiene, polyvinyl acetate and polystyrene acrylate.    
     
     
         83 . An article in accordance with  claim 59 , wherein the second protective coating comprises a wax.  
     
     
         84 . An article in accordance with  claim 83 , wherein the wax is petrolatum.  
     
     
         85 . An article in accordance with  claim 83 , wherein the second protective coating has a thickness of 0.01 μm to 100 μm.  
     
     
         86 . An article in accordance with  claim 59 , wherein the second protective coating comprises polymer particles.  
     
     
         87 . An article in accordance with  claim 85 , wherein the polymer particles are polymer beads having a particle size ranging from 0.1 μm to 1 mm.  
     
     
         88 . An article in accordance with  claim 86 , wherein the polymer particles are selected from poly(styrene-divinylbenzene), poly(methyl methacrylate), polyvinyl chloride, polyvinyl dichloride, poly(styrene butadiene), polyvinyl acetate, and mixtures thereof.  
     
     
         89 . An article in accordance with  claim 59 , wherein the cleaning composition is a basic aqueous solution having a pH of equal to or above 10.  
     
     
         90 . An article in accordance with  claim 59 , wherein the protective coatings reduce the number per unit area of glass chips adhered to the surface upon removal of the coatings by at least 90 percent compared to the number per unit area of glass chips adhered to an uncoated surface under comparable conditions.  
     
     
         91 . An article in accordance with  claim 90 , wherein the number per unit area of glass chips adhered to the surface is reduced by at least 95 percent.  
     
     
         92 . An article in accordance with  claim 59 , wherein the protective coatings reduce the number of scratches on the glass surface per unit area by at least 90% compared to the scratches per unit area on an uncoated glass surface under comparable conditions.  
     
     
         93 . An article in accordance with  claim 92 , wherein the number of scratches per unit area is reduced by at least 95%.  
     
     
         94 . An article in accordance with  claim 59 , wherein the glass comprises at least two substantially flat surfaces, and both surfaces have the first protective coating and the second protective coating.  
     
     
         95 . An article in accordance with  claim 61 , wherein the glass is suitable for producing the substrate of a liquid crystal display.