Login| Sign Up| Help| Contact|

Patent Searching and Data


Title:
DISPERSANTS FOR INORGANIC MATERIALS IN AQUEOUS SYSTEMS
Document Type and Number:
WIPO Patent Application WO/1997/015382
Kind Code:
A1
Abstract:
In an improved process for the preparation of a dispersion of inorganic materials in an aqueous medium, the improvement comprising incorporating into the aqueous medium a dispersant selected from the group consisting of 1) a hydrolyzed, partially esterified ethylenically unsaturated aromatic/maleic anhydride copolymer, 2) a hydrolyzed alpha-olefin/maleic anhydride copolymer, and 3) a hydrolyzed partial ester of an alpha-olefin/maleic anhydride copolymer, and the resulting compositions are disclosed.

Inventors:
Brevett
Carol
Annona
Simmons, May
Donald
Douglas, Wingrave
James
Allan
Application Number:
PCT/US1996/016271
Publication Date:
May 01, 1997
Filing Date:
October 11, 1996
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
DU PONT DE NEMOURS AND COMPANY.
International Classes:
A61K8/04; A61K8/19; A61K8/25; A61K8/26; A61K8/27; A61K8/28; A61K8/29; A61K8/81; A61Q17/04; B01F17/00; B01F17/52; C09D7/02; C09D17/00; (IPC1-7): B01F17/00; A61K7/40; A61K7/48; C09D7/02
Foreign References:
EP0541477A11993-05-12
GB758986A1956-10-10
Other References:
STN International, File CAPLUS, CAPLUS accession no. 1996:294921, S K Kaken KK: "Water-based titanium oxide pastes having high contents of the pigment", JP,A2,08034953, 960206, Heisei
Download PDF:
Claims:
What is claimed:
1. In an improved process for the preparation of a dispersion of inorganic materials in an aqueous medium, the improvement comprising incorporating into the aqueous medium a dispersant selected from the group consisting of 1) a hydrolyzed, partially esterified ethylenically unsaturated aromatic maleic anhydride copolymer, 2) a hydrolyzed alphaolefin/maleic anhydride copolymer, and 3) a hydrolyzed partial ester of an alphaolefin/maleic anhydride copolymer.
2. The process of Claim 1 wherein the hydrolyzed, partially esterified ethylenically unsaturated aromatic/maleic anhydride copolymer has polymeric units of formula I: ~[~(CH2CHR)m— CH — CH — ]n I I I c=o c=o I I YRα OX wherein Rl is an alkyl of 1 to 18 carbon atoms; X is selected from the group consisting of ammonium, substituted ammonium, and alkali metal ions; Y is O, S, NRi. or NH; R is wherein R2 is R5CH=C(R6), or CH2=CH=CH2; R5 is H, CH3 or phenyl; R6 is H or CH3; R.
3. is H or CH3O; and R.
4. is H, CH3 or CH3C(0)0; and R3 and R4 can be taken together to be 0CH20; m is 1 to 10; and n is 1 to 50; the hydrolyzed alphaolefin/maleic anhydride copolymer has polymeric units of formula II: ~[(CH2CHR)m— CH— CH— ]n— II I I c=o c=o I I ox ox wherein R is an alphaolefinic group having 4 to 16 carbon atoms; X is selected from the group consisting of ammonium, substituted ammonium, and alkali metal ions; m is 1 to 10; amd n is 1 to 50; and 3) the hydrolyzed partial ester of an alphaolefin/maleic anhydride copolymer has polymeric units of formula III: ~[(CH2CHR)m — CH— CH~]n — III c=o c=o YRl OX wherein R is an alphaolefinic group having 4 to 16 carbon atoms; Rx is an alkyl of 1 to 18 carbon atoms; X is selected from the group consisting of ammonium, substituted ammonium, and alkali metal ions; Y is O, S, NRι, orNH; m is 1 to 10; and n is 1 to 50.
5. 3 The process of Claim 1 wherein the dispersant has a number average molecular weight of from about 500 to about 5000, and wherein the alpha olefin/maleic anhydride copolymer has a ratio of units derived from alcohol to units derived from maleic anhydride of from about 0.1:1 to about 1:1.
6. An improved aqueous metal oxide composition comprising an oxide of a metal selected from the group consisting of tin, titanium, chromium, iron, antimony, vanadium, cobalt, copper, nickel, zinc, silver, molybdenum, manganese, tungsten, antimony doped tin, zirconium, aluminum, yttrium, europium, silica and mixtures thereof dispersed in an aqueous medium wherein the improvement comprises incorporating therein a dispersant selected from the group consisting of 1) a hydrolyzed, partially esterified ethylenically unsaturated aromatic/maleic anhydride copolymer, 2) a hydrolyzed alphaolefin/maleic anhydride copolymer, and 3) a hydrolyzed partial ester of an alphaolefin/maleic anhydride copolymer.
7. The metal oxide composition of Claim 5 wherein the hydrolyzed, partially esterified ethylenically unsaturated aromatic/maleic anhydride copolymer has polymeric units of formula I: [(CH2CHR)m CHCH]n— I I I c=o c=o I I YRl OX wherein Rl is an alkyl of 1 to 18 carbon atoms; X is selected from the group consisting of ammonium, substituted ammonium, and alkali metal ions; Y is O, S, NRι, or NH; R is wherein R2 is R5CH=C(R6), or CH2=CH=CH ; R5 is H, CH3 or phenyl; R.
8. is H or CH3; R3 is H or CH3O; and R4 is H, CH3 or CH3C(0)0; and R3 and R4 can be taken together to be 0CH20; m is 1 to 10; and n is 1 to 50; 2) the hydrolyzed alphaolefin/maleic anhydride copolymer has polymeric units of formula II: ~[~(CH2CHR)m— CH— CH— ]n— II I I c=o c=o I I ox ox wherein R is an alphaolefinic group having 4 to 16 carbon atoms; X is selected from the group consisting of ammonium, substituted ammonium, and alkali metal ions; m is 1 to 10; and n is 1 to 50; and 3) the hydrolyzed partial ester of an alpha olefin/maleic anhydride copolymer has polymeric units of formula III: [(CH2CHR)m— CH— CH— ]n— III I I c=o c=o I I YRl OX wherein R is an alphaolefinic group having 4 to 16 carbon atoms; Rl is an alkyl of 1 to 18 carbon atoms; X is selected from the group consisting of ammonium, substituted ammonium, and alkali metal ions; Y is O, S, NRι, or NH; m is 1 to 10; and n is 1 to 50.
9. 6 The composition of Claim 5 formulated as a clear coating or a static dissipative coating.
10. The composition of Claim 5 further comprising a polyester resin and an agent for crosslinking said resin.
11. An improved aqueous latex surface coating composition comprising a water soluble inorganic pigment dispersed in an aqueous latex of a filmforming polymer wherein the improvement comprises incorporating therein a dispersant selected from the group consisting of 1) a hydrolyzed, partially esterified ethylenically unsaturated aromatic/maleic anhydride copolymer, 2) a hydrolyzed alphaolefin/maleic anhydride copolymer, and 3) a hydrolyzed partial ester of an alphaolefin/maleic anhydride copolymer.
12. The latex surface coating composition of Claim 9 wherein: the hydrolyzed, partially esterified ethylenically unsaturated aromatic/maleic anhydride copolymer has polymeric units of formula I: ~[~(CH2CHR)m— CH— CH]n I I c=o c=o I I YRl OX wherein Rl is an alkyl of 1 to 18 carbon atoms; X is selected from the group consisting of ammonium, substituted ammonium, and alkali metal ions; Y is O, S, NRι, or NH; R is wherein R2 is R5CH=C(R6), or CH =CH=CH2; R5 is H, CH3 or phenyl; R is H or CH3; R3 is H or CH3O; and R is H, CH3 or CH3C(0)0; and R3 and R4 can be taken together to be 0CH20; m is 1 to 10; and n is 1 to 50; 2) the hydrolyzed alphaolefin/maleic anhydride copolymer has polymeric units of formula II: ~[~(CH2CHR)m — CH— CH— ]n— II I I c=o c=o I I ox ox wherein R is an alphaolefinic group having 4 to 16 carbon atoms; X is selected from the group consisting of ammonium, substituted ammonium, and alkali metal ions; m is 1 to 10; and n is 1 to 50; the hydrolyzed partial ester of an alpha olefin/maleic anhydride copolymer has polymeric units of formula III: __[__(CH2CHR)m CHCHln» III c=o c=o YRl OX wherein R is an alphaolefinic group having 4 to 16 carbon atoms; Rl is an alkyl of 3 to 18 carbon atoms; X is selected from the group consisting of ammonium, substituted ammonium, and alkali metal ions; Y is O, S, NRι, or NH; m is 1 to 10; and n is 1 to 50.
13. An improved titanium dioxide composition wherein the improvement comprises incorporating therein a dispersant selected from the group consisting of 1) a hydrolyzed, partially esterified ethylenically unsaturated aromatic/maleic anhydride copolymer, 2) a hydrolyzed alphaolefin/maleic anhydride copolymer, and 3) a hydrolyzed partial ester of an alphaolefin/maleic anhydride copolymer.
14. The improved titanium dioxide composition of Claim 10 wherein 1) the hydrolyzed, partially esterified ethylenically unsaturated aromatic/maleic anhydride copolymer has polymeric units of formula I: [_(CH2CHR)m— CHCH]n~ I I I c=o c=o I I YRl OX wherein Rl is an alkyl of 1 to 18 carbon atoms; X is selected from the group consisting of ammonium, substituted ammonium, and alkali metal ions; Y is O, S, NRι, orNH; R is wherein R2 is RsCH=C(R6), or CH2=CH=CH ; R5 is H, CH3 or phenyl; R is H or CH3; R3 is H or CH3O; and R4 is H, CH3 or CH3C(0)0; and R3 and R4 can be taken together to be 0CH20; m is 1 to 10; and n is 1 to 50; the hydrolyzed alphaolefin/maleic anhydride copolymer has polymeric units of formula II: ~[~(CH2CHR)m— CH— CH— ]n— II I I c=o c=o I I ox ox wherein R is an alphaolefinic group having 4 to 16 carbon atoms; X is selected from the group consisting of ammonium, substituted ammonium, and alkali metal ions; m is 1 to 10; and n is 1 to 50; 3) the hydrolyzed partial ester of an alpha olefin/maleic anhydride copolymer has polymeric units of formula III: ~[~(CH2CHR)m— CH— CH— ]n— III I I c=o c=o I I YRl OX wherein R is an alphaolefinic group having 4 to 16 carbon atoms; Rl is an alkyl of 1 to 18 carbon atoms; X is selected from the group consisting of ammonium, substituted ammonium, and alkali metal ions; Y is O, S, NRι, or NH; m is 1 to 10; and n is 1 to 50.
15. The titanium dioxide composition of Claim 11 formulated as a cosmetic cream, lotion, sunscreen or sunblock.
16. A dry coating comprising the composition of Claim 5, 9 or 11.
Description:
TITLE DISPERSANTS FOR INORGANIC MATERIALS IN AQUEOUS SYSTEMS

FIELD OF THE INVENTION The present invention relates to an improved process for preparation of a dispersion of inorganic pigments and other inorganic materials in aqueous systems comprising incorporation therein of particular dispersants. The dispersants comprise alpha-olefin maleic anhydride polymers, hydrolyzed partial esters and esters thereof, or esterified hydrolyzed ethylenically unsaturated aromatic/maleic anhydride polymers. The present invention also relates to improved aqueous metal oxide compositions, latex surface coating compositions and cosmetic compositions and dried coatings of such compositions.

BACKGROUND OF THE INVENTION Dispersants are used to prevent settling of solid particles in liquid media. For disperse systems such as paints, cosmetics and other formulations, the solid particles or pigment must be well dispersed in the liquid medium to provide optimum properties in films or coatings and to improve their performance. An effective dispersant prevents settling and occlusion of the solids and enables a uniform distribution of the solid material in the medium. Further the dispersion must remain stable during commercial processing and be effective in sufficiently low economical concentrations.

U. S. Patent 3,322,713 describes a dispersing agent used to disperse organic materials in aqueous or organic media comprising a salt of an alkyl ester of an olefin-maleic anhydride copolymer having as cation, an alkali metal, an ammonium or a substituted ammonium, having a weight average molecular weight of up to about 10,000, having the alkyl ester portion derived from an alkyl alcohol having 3-18 carbon atoms. An aqueous dispersion of an organic pigment is prepared by dissolving the organic dispersing agent in an aqueous medium, and adding the organic pigment to the aqueous medium while agitating.

U. S. Patent 5,001,004 discloses stain resistant compositions for use on textiles which are comprised of hydrolyzed ethylenically unsaturated aromatic/maleic anhydride polymers. Ethylenically unsaturated aromatic compounds include styrene among others. The number average molecular weight

for styrene/ maleic anhydride polymer is 500-4000. After preparing a styrene-maleic anhydride, it is hydrolyzed using sodium, potassium and/ or lithium hydroxide, or, when using special measures, ammonium hydroxide in order to prepare polymers suitable for use as stain resists. It is directed that hydrolysis should not be carried out in the presence of an alcohol, because then the ethylenically unsaturated aromatic/maleic anhydride polymer can react with the alcohol to form a half -ester, which is deleterious to the stain resist performance of the hydrolyzed polymer.

Dispersants having improved properties over those currently available are needed for use in a variety of applications, in particular for dispersing inorganic materials in aqueous systems. A dispersant which can improve film and paint properties in a disperse system relative to available dispersants is therefore desirable.

SUMMARY OF THE INVENTION The present invention comprises an improved process for the preparation of a dispersion of inorganic materials in an aqueous medium, wherein the improvement comprises incorporating into the aqueous medium a dispersant selected from the group consisting of 1) a hydrolyzed ester of an ethylenically unsaturated aromatic/maleic anhydride copolymer, 2) a hydrolyzed alpha-olefin maleic anhydride copolymer, and 3) a hydrolyzed partial ester of an alpha-olefin maleic anhydride copolymer, which can be used to disperse inorganic materials in aqueous systems. The present invention further comprises an improved aqueous metal oxide composition, an improved latex surface coating composition, and an improved cosmetic composition, wherein the improvement in each comprises incorporating therein a dispersant as described above. The invention further comprises dried coatings of such compositions.

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an improved process for the preparation of a dispersion of inorganic materials in an aqueous medium. The dispersants useful herein, when incorporated into dispersions of an inorganic material in aqueous medium, improve the properties and/ or performance of the dispersion.

The dispersants useful in the process of the present invention comprise 1) a hydrolyzed ester of an ethylenically unsaturated aromatic/maleic anhydride copolymer, 2) an alpha-olefin/maleic anhydride copolymer or 3) a hydrolyzed partial ester of an alpha-olefin/ maleic anhydride copolymer. Preferred are octene-

maleic anhydride partial decyl ester and styrene-maleic anhydride partial decyl ester.

The hydrolyzed, partially esterified ethylenically unsaturated aromatic/maleic anhydride copolymer has polymeric units of formula I:

-[-(CH 2 -CHR) m -CH-CH--] n -- I

I I c=o c=o

I I

YRl OX wherein

R| is an alkyl of 1 to 18 carbon atoms;

X is selected from the group consisting of ammonium, substituted ammonium, and alkali metal ions;

Y is O, S, NR!, or NH;

R is

wherein R 2 is R5-CH=C(R 6 )-, or CH 2 =CH=CH2;

R5 is H, CH3 or phenyl;

R is H or CH3;

R3 is H or CH3O; and

R4 is H, CH3 or CH3C(0)0; and R3 and R4 can be taken together to be

-O-CH2-O-; m is 1 to 10; and n is 1 to 50.

The hydrolyzed alpha-olefin/maleic anhydride copolymer has polymeric units of formula II: ~[~(CH 2 -CHR) m — CH— CH— ] n — II

c=o c=o

I I ox ox wherein

R is an alpha-olefinic group having 4 to 16 carbon atoms;

X is selected from the group consisting of ammonium, substituted ammonium, and alkali metal ions; m is 1 to 10; and n is 1 to 50.

The hydrolyzed partial ester of an alpha-olefin/maleic anhydride copolymer has polymeric units of formula III: -[-(CH 2 -CHR) m — CH— CH-] n — III

I I c=o c=o

I I YRl OX wherein

R is an alpha-olefinic group having 4 to 16 carbon atoms; Rl is an alkyl of 1 to 18 carbon atoms;

X is selected from the group consisting of ammonium, substituted ammonium, and alkali metal ions; Y is O, S, NRi, or NH; m is 1 to 10; and n is 1 to 50.

These dispersants are useful in aqueous formulations with a range of metal oxide particles such as oxides of tin, titanium, chromium, iron, vanadium, cobalt, copper, nickel, zinc, silver, molybdenum, manganese, tungsten, antimony doped tin, zirconium, aluminum, yttrium, europium, silica or mixtures thereof. Included are tin oxide-based electroconductive powders, such as ZELEC ECP-3010- XC and titanium dioxide powders, such as TI-PURE and UFT-520AL, all available from E. I. du Pont de Nemours and Company, Wilmington, Delaware. Such formulations include opaque paints, clear coatings and varnishes, electroconductive paints, static-dissipative coatings, conductive coatings, oil-in-water and water-in-oil emulsions, and emulsions for cosmetic purposes. Preferred formulations contain a polyester resin and an agent for crosslinking the resin.

When used to disperse pigmentary-sized particles, that is , particles of about 0.2 to 20 microns, preferably 0.2 to 0.6 microns, properties such as hiding power and gloss are improved. When used to disperse ultrafine particles, that is, particles of less than 0.2 microns, preferably less than 0.1 microns diameter, the coatings formed from the dispersions become more transparent. Emulsions which are made from ultrafine titanium dioxide and these dispersants are transparent when rubbed onto the skin, with no whitish residue, and also give good protection from ultraviolet (UV) radiation. Therefore the process of the present invention is

useful in the preparation of improved dispersions, in particular, improved paint, cosmetic, and electroconductive compositions.

Preparation of the dispersants used in the process and compositions of the present invention is achieved by first preparing a maleic anhydride copolymer. Ethylenically unsaturated aromatic monomers which may be used to prepare the aromatic/maleic anhydride copolymer dispersant can be represented by formula:

wherein R 2 is Rs-CH=C (R6)- or CH 2 =CH-CH 2 =; R5 is H, CH3 or phenyl; Rβ is H or CH3; R3 is H or CH3O-; and R4 is H, CH3, or CH3C(0)0; and R3 and R4 can be taken together to form -0-CH 2 -0-.

A copolymer of the ethylenically unsaturated aromatic monomer and maleic anhydride can be prepared with a molar ratio of aromatic to maleic anhydride typically about 1:1 as dictated by chemical reactivity. The copolymer can have number average molecular weights in the range between about 500 and 5000, preferably between about 800 and 2000, and an acid number of about 150 to 500. The copolymers are readily soluble in water at neutral to alkaline pH. Increasing dilution is required at a pH below 6. The copolymers are also soluble in lower alcohols, such as methanol, and are somewhat soluble in acetic acid. Procedures for producing styrene-maleic anhydride copolymers are well known to skilled artisans. A styrene-maleic anhydride copolymer resin which is commercially available and suitable for use in this invention is SMA-1000 available from Atochem North America Inc., 3 Parkway, Philadelphia, Pennsylvania 19102.

The ester portion of this dispersant is derived from alkyl alcohols having an aliphatic moiety of 1-18 carbon atoms. Typical examples of the alcohols that can be used are propyl alcohol, butyl alcohol, decyl alcohol, and octadecyl alcohol. The amount of alcohol added relative to the amount of the ethylenically unsaturated aromatic/maleic anhydride copolymer is from 10 mole percent to 50 mole percent, perferably from 20 mole percent to 40 mole percent, most preferably about 30 mole percent. Mole percent is used to refer to the total moles of acid groups available (not the total moles of compound available). These conditions are such to achieve partial esterification. It is preferred that less than half of the acid groups are esterified.

Suitable hydrolyzing agents for preparing the dispersants from the esterified copolymer include alkali metal hydroxides, especially sodium hydroxide, and ammonium or substituted ammonium hydroxides. The amount of hydrolyzing agent present can be from about 10:1 to about 1:1 as a molar ratio, typically about 1:1.

To prepare the hydrolyzed esters of ethylenically unsaturated aromatic/maleic anhydride copolymers used in this invention, first an ethylenically unsaturated aromatic/maleic anhydride copolymer is stirred into water. These copolymers are soluble in water if base is added. The copolymer solution is heated to a temperature of from 60 to 100°C.

An alkyl alcohol having an aliphatic moiety of 1-18 carbon atoms is added to the heated copolymer solution over a period of time of from about 5 to about 200 minutes. This mixture is then maintained at a temperature of from about 60°C to about 100°C for a time of from about 3 to about 24 hours, preferably at about 100°C for about 6 hours, to esterify the copolymer.

The temperature of the mixture containing the esterified copolymer is adjusted to about 60°C. To the esterified copolymer is then added a sufficient amount of a hydrolyzing agent to fully hydrolyze the esterified copolymer. The mixture is stirred for from about 10 to about 60 minutes. After the hydrolysis step, the mixture is cooled to ambient temperature and the product is analyzed for percent solids. The pH is adjusted to 8-9 and the percent solids is adjusted to a desired range suitable for the end use intended.

This preparation process is represented by the following reaction sequence wherein R is an ethylenically unsaturated aromatic group, R x is Ci-C^g alkyl, m and n represent the number of repeating units in the copolymer and X is a positively charged ion selected from the group consisting of an alkali metal ion such as sodium ion, potassium ion, ammonium ion, or substituted ammonium ion.

A second dispersant useful in the process and compositions of the present invention is a hydrolyzed alpha-olefin/maleic anhydride copolymer, or a hydrolyzed partial or full ester thereof. Suitable olefins which may be used to prepare the olefin/ maleic anhydride copolymer include alpha-olefins having 4 to 18 carbon atoms. A copolymer of the olefin and maleic anhydride can be prepared using a molar ratio of olefin to maleic anhydride of from about 0.25:1 to about 4.0:1. Preferably the amount of maleic anhydride is maximized consistent with effective polymerization. Procedures for producing olefin/ maleic anhydride copolymers are well known in the art. Alpha-olefin/maleic anhydride copolymers useful in the present invention are commercially available from Petrolite Corporation, 6910 E. 14th Street, Tulsa, Oklahoma 74112. The alpha-olefin/maleic anhydride copolymers are then hydrolyzed. Suitable hydrolyzing agents for preparing dispersants from the copolymer include alkali metal hydroxides, in particular sodium hydroxide and potassium hydroxide, and ammonium or substituted arnmonium hydroxides. The amount of hydrolyzing agent as a molar ratio to alpha-olefin/maleic anhydride copolymer used is from about 10:1 to about 1:1, typically about 1:1. The hydrolyzed alpha-olefin/maleic anhydride copolymer is useful as a dispersant for inorganic materials in aqueous systems.

A third dispersant useful in the process and compositions of the present invention is a hydrolyzed partially esterified alpha-olefin/maleic anhydride copolymer. The ester portion of these dispersants is derived from alkyl alcohols

having an aliphatic moiety of 1-18 carbon atoms. Typical examples of the alcohols which can be used are propyl alcohol, butyl alcohol, decyl alcohol, and octadecyl alcohol. The ratio of alcohol relative to the amount of maleic anhydride in the copolymer is from about 0.01:1 to about 1:1, preferably from about 0.3:1 to about 0.8:1. The partially esterified alpha-olefin/maleic anhydride polymers are suitable for use in the present invention after being hydrolyzed.

The alkyl esters of an alpha-olefin-maleic anhydride copolymer employed in the practice of this invention may be prepared as described above for the first dispersant. The present invention further comprises improved aqueous metal oxide coating compositions of an oxide of a metal selected from the group consisting of tin, titanium, chromium, iron, antimony, vanadium, cobalt, copper, nickel, zinc, silver, molybdenum, manganese, tungsten, antimony doped tin, zirconium, aluminum, yttrium, europium, or a mixture thereof, dispersed in an aqueous medium such as water wherein the improvement comprises incorporating therein a dispersant selected from the group consisting of 1) a hydrolyzed partially esterified ethylenically unsaturated aromatic/maleic anhydride copolymer, 2) a hydrolyzed alpha-olefin/maleic anhydride copolymer, and 3) a hydrolyzed partial ester of an alpha-olefin/maleic anhydride copolymer. To make the improved coatings of the present invention, at least one of the three types of dispersants prepared as described above is dissolved, usually under agitation, in a portion of an aqueous medium, such as water. The inorganic solids are then added under agitation, and are milled for example with 0.8 to 1 millimeter zirconium silicate beads for 24 hours. The solids are then adjusted to the desired concentration by addition of the remainder of the aqueous medium. The metal oxide particles may provide another functionality other than filler. For example; if electroconductive tin oxide particles are used, a transparent conductive coating may be made. If titanium dioxide particles of less than 0.1 micron diameter are used, a coating which is transparent to visible light but absorbs ultraviolet light may be made. To obtain transparency, the metal oxide particles are preferably less than 0.1 micron in diameter.

Included within the improved aqueous metal oxide coating compositions of the present invention are titanium dioxide compositions. The improved titanium dioxide compositions have incorporated therein a dispersant selected from the group consisting of 1) a hydrolyzed partially esterified ethylenically unsaturated aromatic/maleic anhydride copolymer, 2) a hydrolyzed alpha-olefin/maleic anhydride copolyer, and 3) a hydrolyzed partial ester of an

alpha-olefin/maleic anhydride copolymer. These titanium dioxide compositions are able to absorb and scatter ultraviolet light and therefore are useful as ingredients in sunscreen formulations and cosmetics formulations, such as creams or lotions. Such sunscreen and cosmetic formulations are also included within the present invention. Processes for preparation of such sunscreens and cosmetics are well known in the art. For example, for preparation of sunscreens and cosmetics see Dahms, Cosmetics and Toiletries, 107, pp. 133-143, (Oct. 1992), or Woodruff, J., "Formulating Sun Care Products with Micronized Oxides," Cosmetics and Toiletries Manufacture Worldwide, 1994 (Aston) pp. 179-185. Data on improved sun protection factors for titanium dioxide compositions of the present invention are provided in the examples hereinafter. The compositions are transparent to visible light while providing excellent ultraviolet screening properties. Suitable dispersant-to-pigment ratios (D/P) are less than about 0.3/1; preferably less than 0.05/1 in compositions having a percentage of ultrafine titanium solids of about 70% or less. The degree of dispersion may be evaluated by obtaining the particle size in the particles in the dispersion, using either standard transmission electron microscopy or low angle laser light scattering.

The ability of the titanium dioxide compositions to absorb and scatter ultraviolet light makes them useful as ingredients in many other compositions such as food packaging materials, wood coating, coatings on vinyl and other architectural materials, glass coatings, and automotive clearcoats. The dispersants used herein have a wide range of compatibility with acrylic, urethane, polyester and other resins. Preparation of such coatings are well known and are described in Myers, R.R. and Long J.S. (Eds) "Treatise on Coatings", Vol. 4, Part I; formulations, Marcel Dekker, New York, New York (1975.)

The present invention further comprises an improved aqueous latex surface coating composition (paint composition) comprising a water soluble inorganic pigment dispersed in an aqueous latex of a film-forming polymer wherein the improvement comprises incorporating therein a dispersant selected from the group consisting of 1) a hydrolyzed, partially esterified ethylenically unsaturated aromatic/maleic anhydride copolymer, 2) a hydrolyzed alpha-olefin.maleic anhydride copolymer, and 3) a hydrolyzed partial ester of an alphaolef in/ maleic anhydride copolymer. The improved latex coating compositions, i.e., paints, have improved gloss and hiding power when compared to conventional paints due to the improved dispersion as demonstrated in the examples hereinafter. The improved paints of the present invention are prepared by conventional techniques known in the art. Such formulation techniques are described, for example, in G.P. A. Turner,

"Introduction to Paint Chemistry and Principles of Paint Technology" 2nd Ed., Chapman and Hall Ltd., New York, New York (1980).

The present invention also comprises a dry coating composition comprising the above described metal oxide compositions, latex surface coating compositions, and titanium dioxide compositions in dried form after application to a substrate.

EXAMPLES Example 1 Into a 1000 ml round bottom flask fitted with a mechanical stirrer, condenser, and nitrogen inlet and having a feedback controlled heating mantle, was placed 250 grams of water and then 125 grams of SMA 1000, a 1:1 copolymer of styrene and maleic anhydride having a number average molecular weight of 1600, available from Atochem North America Inc., 3 Parkway, Philadelphia, Pennsylvania 19102. The contents of the flask were heated to 80°C at which time, 24 grams of decyl alcohol was added over a 2 hour period. The mixture was heated overnight and cooled to 60°C. At that time, 60 grams of 28% ammonium hydroxide in 300 ml of water was added. After addition, the contents of the flask were stirred for 30 minutes and analyzed for percent solids. Solids were determined by washing the solution, heating in a vacuum oven to remove solvent and reweighing. Active ingredient was 17.5%.

Example 2 A latex paint was made of the following formula:

RAW MATERIAL LBS. (KG, GAL. Liters

Water 2.6 (1.18) 0.31 (1.2)

Propylene Glycol 65.00 (29.48) 7.51 (28.4)

Dispersant of Example 1 15.00 (2.40) 1.56 (5.91)

Foamaster VL 1.00 (0.45) 0.13 (0.49)

Kathon LX (1.5%) 1.70 (0.77) 0.20 (0.76)

Ti0 2 Ti-Pure®R-706 268.00 (121.56) 8.04 (30.4)

Water 88.00 (39.92) 10.56 (39.97)

Rhoplex SG-10M 495.00 (224.53) 56.02 (212.0)

Texanol 18.50 (8.39) 2.33 (8.82)

Triton X-405 2.50 (1.13) 0.27 (1.0)

Foamaster VL 1.00 (0.45) 0.13 (0.49)

Acrysol 1020 39.50 (17.92) 4.57 (17.3)

Water 68.66 (31.14) 8.24 (31.2)

Foamaster VL is available from Henkel Corporation, Ambler, Pennsylvania 19002. Kathon LX, Rhoplex SG-10M, Triton X-405 and Acrysol 1020 are available from Rohm & Haas Company, Philadelphia, Pennsylvania. Texanol is available from Eastman Chemical Company, Rochester, New York 14650. Ti0 2 is available from E. I. du Pont de Nemours and Company, Wilmington, Delaware.

The Ti0 2 was first wetted with water and dispersant to a 70-80 weight to weight ratio. Then the first 11 materials listed above were mixed and ground for 30 minutes. A "pre-mix" containing Acrysol 1020 and water was then prepared and added to the ground mixture for a "let-down" step. This mixture was mixed an additional 10-15 minutes to provide the paint.

A comparative paint was prepared in the same manner as described above with the exception that instead of a dispersant of this invention, 5.40 lb (2.4 kg) or 0.55 gal (0.21 cc) of a commercial dispersant, (50%), and 12.0 lbs (5.44 kg) or 1.44 gal (0.54 cc) of water in place of 2.6 lb (1.18 kg) or 0.31 gal (0.12 cc) of water, was used.

The hiding power of each paint was measured by the following procedure which is related to ASTM D2805. A drawdown of the paint to be tested was made on preweighed Morest Chart using a bird film applicator blade at 0.90- 0.95 contrast ratio at 72°F, (22°C) 50% relative humidity. The treated chart was weighed 20 seconds after the drawdown had been completed. Quadruplicate drawdowns were made. The average weight of the four drawdowns was used in the calculation.

Reflectance readings were made of the drawdowns on a Gardner Automatic Multipurpose Reflectometer available from Byk Gardner Company, Silver Springs, Maryland 20910 using green filter. One reading was taken on each of two "white" and "black" sections of each of the four charts. Contrast ratio was calculated by dividing the average reflectance over the black area by the average over the white. Scattering power (SX value) is read from the appropriate Kubelka- Munk Opacity Chart chosen by substrate reflectance using values of contrast ratio and reflectance over black.

The scattering coefficient (S) in units of square meters per gram of τjfj2 was calculated by the following: S = [ (SX) (A) (d) ] / [ (Wf) (C) (1550) ] SX . A is the Kubelka-Munk chart value A = area of paint film in square inches. 1550 is the square inches per square meter, d is the paint density in pounds per gallon. Wf is the weight of wet paint film in grams. C is the concentration of Ti0 in paint in pounds per gallon.

The 60 degree gloss of each paint was measured according to ASTM D523, hereby incorporated by reference. Using an automatic drawdown machine at 0.002 inches, a film of each paint was applied to separate black PVC panels. Each treated panel was placed in an environmental chamber at 108°F (87°C) at 60% relative humidity for 3 hours and 3 minutes. The 60 degree Gloss was read using a Gardner Haze-Gloss meter, catalog number 4606, available from Byk Gardner Company, Silver Springs, Maryland 20910. At least two readings were taken from each panel. The average reading was used as the gloss meter reading of that sample. Gloss is corrected by the following formula: Gloss = LSV + [ { (SMR - LMR) / (HMR - LMR) } x (HSV - LSV) ]. LSV is the assigned low standard value. HSV is the assigned high standard value. LMR is the low standard meter reading. HMR is the high standard meter reading. SMR is the sample meter reading

In comparing the hiding power and gloss values of the two paints, it was found that the hiding power was increased by 13% and the 60 degree gloss was improved by 5 degrees in the paint containing the dispersant of this invention relative to the paint containing the commercial dispersant.

Example 3 A dispersion of ultrafine titanium dioxide was prepared as follows. A master dispersion was prepared by mixing 30 grams of ultrafine Ti0 2 with 15 grams of the dispersant prepared in Example 1, 28% by weight in water, and 346 grams of water. This mixture was milled in a Union Process 01 research attritor using 0.8 mm zirconium silicate beads at 500 rpm for 24 hours to provide a dispersion of finely divided particles of ultrafine powder. 5 grams of this master dispersion was mixed with 18.2 grams of Carboset 514H, aqueous acrylic resin, available from B. F. Goodrich, 9911 Brecksville Rd, Brecksville, Ohio 44141, to provide a dispersion containing 5% Ti0 2 based on the dry weight of the Ti0 2 and the resin. A drawdown of this dispersion was made onto a polypropylene sheet using a #8 rod. The sun protection factor (SPF) was determined by the procedure and was found to be 3.9. A second dispersion of ultrafine Ti0 2 was prepared in the same manner as described above with the exception that a commercial dispersant, was used instead of a dispersant of this invention. The SPF of this second dispersion was 1.6.

Determination of sun protection factors was performed by the method of Duffey and Robson, J. Soc. Cosmet. Chem., 1989, 40, pp. 127-133, hereby incorporated by refrence. An Optometrics SPF-290 Analyzer (available from Optometrics USA Inc., Auer, Massachusetts.) and described by Sellers and

Carpenter in Cosmetics and Toiletries, 1992, 107, pp. 119-122, hereby incorporated by reference, was used. As noted above polypropylene sheet was used as the substrate to coat with the dispersions instead of the surgical tape used in the above references. Examples 4 -6

All of the compositions listed in Table I below were made as follows: 7.7% UFT-520AL - Ultrafine Titanium Dioxide available from E. I. du Pont de Nemours and Company, Wilmington, Delaware; 1.1% dispersant; and 91.2% distilled water, were milled in a Union Process 01 attritor mill for 24 hours. 450 grams of millbase were loaded, with 850 grams of 0.8 to 1mm zirconium silicate beads. After milling the beads were filtered out, and 1 gram of the resultant millbase was added to 4.4 grams of aqueous polyester resin (Eastman AQ38, 30% solids, available from Eastman Chemical Company, Rochester, New York). A drawdown (dry resin/ metal oxide mixture on a support) of this dispersion onto Mylar (grade GA-10; 5 mils thick) available from E. I. du Pont de Nemours and Company, Wilmington, Delaware, was made with a #8 wirewound rod (nominal 20.5 microns dry film thickness). The film thus formed was about 5.5% Ti0 2 and 94.5% resin. Haze and transparency measurements were then taken on a Hunter ColorQUEST available from Hunter Associates Laboratory, Inc., 11491 -T Sunset Hills Rd., Reston, Virginia 22090, D65 Illuminant, 2 degree observer angle using the following method.

The dispersion (resin & metal oxide mixture) was spread onto a transparent support (e.g. mylar, transparencies). A Hunter ColorQUEST with D65 Illuminant, and 2 degree observer angle was used to provide and collect the light. The light was shone through a 1" diameter piece of sample. Both the amount of transmitted diffuse light and total transmitted light was measured. The % Haze = 100* (diffuse transmitted/ total transmitted). Samples of less than 10% Haze are considered somewhat transparent; samples of less than 3% Haze are considered transparent. The low haze values obtained in thiese examples were an indication of good dispersion and low white cast, and were desirable for cosmetic applications. Another drawdown was made by mixing 1 gram of the millbase with 18.2 grams Carboset 514H aqueous acrylic resin (BF Goodrich Specialty Chemicals, 9911 Brecksville Rd., Cleveland, Ohio. A #8 wirewound rod was used to make drawdowns onto polypropylene film. UV/ visible absorption measurements were taken, and the SPF (sun protection factor) was also measured using the method given in Example 3. The SPF values in the table below showed that the ultrafine

titanium dioxide particles still absorbed and scattered UV rays, thus protecting the substrate from the UV, while remaining transparent.

The comparative examples used were commercially available dispersants as follows: A) 1 propanol ester of styrene/ maleic anhydride copolymer,

B) 2-butoxyethylester of styrene/ maleic anhydride copolymer,

C) Mixed cyclohexanol isopropyl ester of styrene/ maleic anhydride copolymer,

D) diisobutylene/ maleic anhydride copolymer,

E) phosphate ester of perfluoroalkyl ethylalcohol. Comparative examples A, B and C were ammonia neutralized and are representative of a hydrolyzed, partially esterified ethylenically unsaturated aromatic maleic anhydride copolymer dispersants. Comparative example D is representative of a hydrolyzed alpha-olefin maleic anhydride copolymer. Comparative example E is available from E. I. du Pont de Nemours and Company, Wilmington, Delaware.

The dispersants used in examples 4-6 were as follows:

4) 1-octene xylene maleic anhydride terpolymer,

5) 1 -octene maleic anhydride copolymer,

6) decylester of styrene maleic anhydride copolymer. Examples 4 and 5 were sodium neutralized and are repesentaive of a hydrolyzed alpha-olefin/maleic anhydride copolymer dispersant. Example 6 was ammonia neutralized and is representaitve of a hydrolyzed partially esterified ethylenically unsaturated aromatic maleic anhydride copolymer dispersant.

TABLE I

%TRANS

COMPARATIVE EXAMPLES HAZE PARENCY SPF

A 11.5 89.4 4.1

B 9.2 89.1 4.9

C 9.6 89.2 5.2

D 15.5 90.1 1.6

E 15.5 90.5 2.5

EXAMPLES

4 3.8 87.8 5.5

5 3.1 89.3 5.1

6 5.2 88.6 4.4

The data in Table I show that the compositions of the present invention were much more effective than the commercially available comparative examples, since the haze values are considerably lower. The mylar sheet used gave a haze value of about 1.0. Example 4, gave a median particle size of 0.077 and the largest particle size was 0.36 (unsonicated); but Example A, gave median particle size of 0.115 and the largest particle size was 1.1 microns (unsonicated).

Examples 7-8 Compositions were prepared in water similarly to those above in Example 4-6, but with different dispersion to pigment ratios and pigment to binder (resin) ratios. The compositions were tested for haze and transparency as in Examples 4-6. The dispersants employed were as follows: Comprative F) diisobutylene/ maleic anhydride copolymer, Example 7) 1 -octene maleic anhydride copolymer Example 8) 1 -octene maleic anhydride copolymer Resulting data is listed in Table II:

TABLE II

EXAMPLE %UFT- a %DISPERSANT D/P HAZE %TRANS C

Comparative F 7.7 0.2 0.025 28.5 91.2

7 7.7 0.16 0.021 8.5 88.9

8 40 2.1 0.053 6.3 88.4 a Percent ultrafine titanium dioxide b Dispersant to pigment ratio c % Transparency Example 9

A composition was prepared in water similarly to those in Examples 4-

6 above but no ultrafine Ti0 was employed. The metal oxide employed was an electroconductive powder, antimony doped tin. The dispersant used was a 1-octene xylene maleic anhydride terpolymer. The compositions were tested for haze, and transparency as previously described and for surface resistivity using a Monroe

Model 278 Precision Resistance/ Current Meter with a Monroe Model 96117-1

Surface/ Volume Resistivity Set Probe available from Monroe Electronics, Inc. 100

Housel Ave., Lyndonville, NY 14098. The method used was in accordance with literature supplied with the equipment. The sample was placed on top of the nonconductive ground plate. The meter was set to a voltage of one (1) volt. The probe was then placed on the sample and a stable resistance value determined.

COMPONENT GRAMS

H 2 0 197

Dispersant, (28%) 7.1 Polyester resin AQ55S(21.4%)* 156

Antimony doped tin, ZELEC ECP-3010-XC** 100

TOTAL: 460

Pigment to binder (resin) ratio = 3/1; Dispersant to pigment ratio = 0.02/1.

* From Eastman Chemical Co. Rochester, New York ** From E. I. du Pont de Nemours and Company, Wilmington, Delaware

A #8 wirewound rod was used to make a drawdown of this dispersion.

Surface resistivity was 16 kiloohms/ square. Haze was 4.1%; total transmitted light was 78.4%.

Example 10 A composition was prepared as in Example 9 above using a 1 -octene maleic anhydride copolymer dispersant and tested for surface resistivity, haze and transparency as previously described.

COMPONENT GRAMS

H 2 0 195

Dispersant (21.3%) 9.4

Polyester Resin AQ55S(21.4%)* 156

Antimony doped tin, ZELEC ECP-3010-XC** 100

TOTAL: 460

Pigment to binder (resin) ratio = 3/1; Dispersant to pigment ratio = 0.02/1.

* From Eastman Chemical Co., Rochester, New York

** From E. I. du Pont de Nemours and Company, Wilmington, Delaware

This millbase was drawndown with a #8 wirewound rod. Surface resistivity was 22 kiloohms/ square. Haze was 2.2%; total transmitted light was 78.5%.

Example 11 A cosmetic lotion was prepared according to the following formula:

CTFA NAME BRAND USED COMPANY AMOUNT (GRAMS,

Propylene glycol dicaprylate Liponate PC (LIPO) 5

Dimethicone (lOOcs) (Dow Corning) 3

Cetyl phosphate and

DEA cetyl phosphate Amphisol K (Givaudan-Roure) 2

Caprylic/ capric triglyceride Liponate GC (LIPO) 7

Hydroxyoctacosanyl hydroxystearate Elfacos C26 (AKZO) 2

Cetearyl alcohol TA1618 (Proctor & Gamble) 0.5

Glyceryl stearate Cerasynt SD (ISP Van Dyk) 5

Mineral Oil (Baker) 3

Total Oil Phase 27.5

Magnesium aluminum silicate Veegum (RT Vanderbilt) 2

Propylene glycol (Baker) 5

Dispersion of 7.7% Ti0 2 , 02% UFT520AL (E. I. duPont de Nemours 65.2

1-octene maleic anhydride- and Co.) copolymer dispersant, water

Total Water Phase 72.2

TOTAL 99.7

* UFT = ultrafine titanium dioxide

A SPF of 7 was obtained using the dispersion of Example 4. The lotion thus formed has been stable for 12 months.