Aqueous metal oxide composition and method for dip coating and electrophotographic applications, and electrophotographic equipment members, particularly electrophotographic drum

1 . A composition for dip coating an article, with a coating comprising at least one metal oxide, the composition comprising:

a) a dispersion of at least one finely-divided particulate metal oxide in water or alcohol, the dispersion containing at least about 15 weight percent metal oxide and being present in the composition in an amount sufficient to produce a metal oxide content in the coating from about 40 to about 80 weight percent;

b) a latex polymer composition in an amount to produce a latex polymer content from about 15 to about 59.5 weight percent in the coating;

c) a water soluble viscosity enhancer in an amount less than about 10 weight percent of the coating; and

d) a water miscible, volatile solvent in an amount equal to from about 35 to about 60 weight percent of the water in the composition.

2 . The composition of claim 1 , wherein the metal oxide is selected from the group consisting of titanium, zirconium, induim, antimony, tin, aluminum and mixtures thereof.

3 . The composition of claim 1 , wherein the metal oxide is tin oxide or titanium oxide.

4 . The composition of claim 1 , wherein the finely divided particulate metal oxide comprises particles less than one micron in size.

5 . The composition of claim 4 , wherein the particles are from about 10 to about 100 nanometers in size.

6 . The composition of claim 1 , wherein the composition contains from about 15 to about 60 weight percent of the metal oxide aqueous dispersion.

7 . The composition of claim 6 , wherein the composition contains from about 15 to about 59.5 weight percent of the latex polymer composition.

8 . The composition of claim 7 , wherein the composition contains from about 0.5 to about 5 weight percent of the aqueous soluble viscosity enhancer.

9 . The composition of claim 1 , wherein the latex polymer is dispersible in water, water and alcohol mixture and alcohol.

10 . The composition of claim 9 , wherein the alcohols are selected from methanol, ethanol and propanol.

11 . The composition of claim 1 , wherein the latex polymer is selected from the group consisting of polyurethane dispersions, polyester polyol dispersions and poly vinyl polyol aqueous dispersions.

12 . The composition of claim 1 , wherein the viscosity enhancer is exponentially effective as the water concentration decreases.

13 . The composition of claim 1 , wherein the latex polymer is anionic.

14 . The composition of claim 1 , wherein the latex polymer contains ammonium carboxylate dispersing groups.

15 . The composition of claim 12 , wherein the viscosity enhancer is hydroxy ethyl cellulose with a molecular weight, Mw below 500,000.

16 . The composition of claim 12 , wherein the viscosity enhancer is hydroxy ethyl cellulose with a molecular weight, Mw of 90,000.

17 . The composition of claim 12 , wherein the viscosity enhancer is at least one of hydroxy ethyl cellulose, starch and xanthan gum.

18 . The composition of claim 12 , wherein the viscosity enhancer is a non-associative viscosity enhancer.

19 . The composition of claim 1 , wherein the composition has a viscosity from about 5 to about 100 centipoises at 25 ° C.

20 . A method for coating a cylindrical outside surface of a cylindrical electrophotographic member, the method comprising:

a) preparing a coating composition comprising;

1) a dispersion of at least one finely-divided particulate metal oxide in water or alcohol, the dispersion containing at least about 15 weight percent metal oxide and being present in an amount sufficient to produce a metal oxide content in the coating from about 30 to about 80 weight percent;

2) a latex polymer composition in an amount to produce a latex polymer content from about 15 to about 59.5 weight percent in the coating;

3) a water soluble viscosity enhancer in an amount less than about 10 weight percent of the coating; and

4) a water miscible, volatile solvent in an amount equal to from about 35 to about 60 weight percent of the water in the composition.

21 . The method of claim 20 , wherein the coating comprises from about 40 to about 80 weight percent of the metal oxide, from about 15 to about 59.5 weight percent of the latex polymer and from about 0.5 to about 5 weight percent of the viscosity enhancer.

22 . The method of claim 20 , wherein the electrophotographic member comprises a drum.

23 . The method of claim 20 , wherein the electrophotographic member comprises a metal sleeve.

24 . The method of claim 20 , wherein the electrophotographic member comprises a nickel sleeve.

25 . The method of claim 20 , wherein the electrophotographic member comprises a seamless plastic open-ended belt.

26 . The method of claim 22 , wherein the composition on the drum is applied by dip coating.

27 . The method of claim 23 , wherein the dried coating has a thickness from about 1 to about 10 to about microns.

28 . The method of claim 24 , wherein the thickness of the coating varies by about +/−0.5 to about 2 microns.

29 . A coating composition for an electrophotographic member comprising:

a) from about 40 to about 80 weight percent of at least one metal oxide;

b) from about 15 to about 59.5 weight percent of a latex polymer; and,

c) from about 0.5 to about 5 weight percent of an aqueous soluble viscosity enhancer.

30 . The coating of claim 27 , wherein the metal oxide is selected from the group consisting of oxides of titanium, zirconium, induim, antimony, tin, aluminum and mixtures thereof.

31 . The composition of claim 27 , wherein the latex polymer is selected from the group consisting of polyurethane dispersions, polyester polyol dispersions and poly vinyl polyol dispersions.

32 . The composition of claim 27 , wherein the viscosity enhancer is selected from the group consisting of hydroxy ethyl cellulose of various molecular weights and PAC-GEL, pre-gelatinized rice flour specially processed from milled rice.