Stain resistant grout

A stain resistant grout composition comprises a mixture of an acrylic latex, an aliphatic urethane and a paraffin. Preferably, the composition is an aqueous composition and is a low volatile organic compound (VOC) composition.

FIELD OF THE INVENTION 
The invention relates to a stain resistant grout composition. More 
particularly, the invention relates to a stain resistant ceramic tile 
grout composition which includes a mixture of an acrylic latex, an 
aliphatic urethane and a paraffin. Preferably, the composition is an 
aqueous composition and is a low volatile organic compound (VOC) 
composition. 
BACKGROUND OF THE INVENTION 
The tendency of ceramic tile grout to stain easily requires a high level of 
maintenance. Overcoming this deficiency has been a high priority for the 
ceramic tile industry for many years. While heat and chemical resistant 
grouts, such as epoxy and furan grouts, exist on the commercial market, 
these grouts contain hazardous ingredients and require the expertise of a 
professional installer. 
The present invention results in a grout product for ceramic tile that is 
highly resistant to a wide variety of staining agents. The composition 
takes two forms: a liquid admix for standard portland cement grout and a 
one component, pre-mixed paste. 
Discho U.S. Pat. No. 5,387,644 discloses a hardenable monomer composition 
useful for grouts. The Disoho composition comprises a mixture of a 
crosslinkable acrylic monomer, carbon black and/or a polyester- or 
polyethermethane oltgomer having at least two polymerizable double bonds 
and a paraffin oil. The oltgomer is an aliphatic or aromatic, bifunctional 
or polyfunctional polyester- or polyether-urethane acrylate. Therefore, 
the Discho composition is not a mixture of an acrylic latex, an aliphatic 
urethane and a paraffin, but the reaction product of a crosslinkable 
acrylic monomer and a reactive acrylic end-capped polyester- or polyether 
urethane. Further, the Discho composition is a liquid and the urethane 
oligomer has a molecular weight of no more than 2,000. 
SUMMARY OF THE INVENTION 
In accordance with the present invention, the stain resistant grout 
composition comprises a mixture of an acrylic latex, an aliphatic urethane 
and a paraffin. Preferably, the composition is 5% to 40% by weight of 
acrylic latex, 0.5% to 15% by weight of aliphatic urethane and 0.5% to 6% 
by weight of paraffin. 
More preferably, the acrylic latex is 10% to 30% by weight of the 
composition, and still more preferably about 15% to about 20% by weight. 
More preferably, the aliphati.sub.c urethane is 0.5% to 10% by weight of 
the composition, and still more preferably about 1% to about 4% by weight. 
More preferably, the paraffin is 0.5% to 3% by weight of the composition, 
and still more preferably 0.5% to 1% by weight. The minimum amounts of the 
components are needed for improved stain resistance. The components 
increase cure time of the composition, therefore less water is trapped 
under the skin which forms on the surface of the composition. 
If the aliphatic urethane is greater than 15%, the composition is too hard 
and tough, and the workability and desired properties are reduced. If the 
paraffin is greater than 6%, adhesiveness of the composition is reduced. 
The preferred aliphatic urethane is a fully reacted, thermoplastic urethane 
and has a molecular weight greater than 10,000. The allphatic urethane is 
preferably dispersed in a blend of water, N-methylpyrrolidone and amine. 
The preferred paraffin is a paraffin wax. 
DETAILED DESCRIPTION OF THE INVENTION 
The acrylic latex serves as the vehicle which carries the other components 
of the composition and dries by evaporation. The acrylic latex provides 
alkali resistance and promotes adhesion. The quick release of volatile 
components in the acrylic latex, compared to other latexes, promotes early 
hardness development. 
The paraffin provides water resistance by "floating" to the surface of the 
composition and forming a shield on the surface of the grout. The paraffin 
provides immediate stain resistance while the acrylic resin and urethane 
cure over the first few hours to three days. 
The urethane enhances volatilization of the latex water, repels external 
water, improve the continuity of the filler, and improves adhesion, 
abrasion resistance, chemical resistance and stain resistance. The 
combination of these components yields a product which dries hard and is 
impervious to penetration by stain carrying agents. 
The grout of the present invention is not only impervious, but also is 
harder than existing cement grouts. Therefore, the present grout also 
improves abrasion resistance. 
The preferred aliphatic urethane is a fully reacted, thermoplastic urethane 
such as Spensol L41-MPW-32, Spensol L44-MPW-32, Spensol L51-MPW-35, 
Spensol L52-MPW-30, Spensol L53-MPW-30, Spensol L54-MPW-32, Spensol 
L55-MPW-35 and Spensol L56-MPW-36, all of which are manufactured by 
Reichhold Chemicals, Inc. Spensol L-MPW-32 and Spensol L44-MPW-32 are less 
expensive resins which can be used when color stability is not critical. 
Spensol L51-MPW-35 has a higher hardness. Spensol L52-MPW-30 has a low 
impact resistance. Spensol L53-MPW-30 has the best abrasion resistance. 
Spensol L54-MPW-32 is suitable for both air dry and force dry application. 
Spensol L55-MPW-35 and Spensol L56-MPW-36 can be used for flexible 
substrates. 
The urethane is preferably a water dispersible polyurethane elastomer; more 
preferably it is dispersed in a blend of water, N-methylpyrrolidone and 
amine. The preferred amine is triethylamine and the preferred weight ratio 
of urethane/water/N-methylpyrrolidone/amine is about 
While the aliphatic urethane dispersion has a small percentage of organic 
solvent, the grout composition is a low VOC composition. Because the 
composition does not include epoxy components, the grout can be exposed to 
UV light without yellowing, i.e. has UV resistance. 
Numerous additives, well known in the art, can be included in the grout 
composition for their known purposes. Such additives include anti-settling 
agents, humectants, pH control agents, biocides, freeze/thaw stabilizers, 
surfactants, fillers/extenders, drying rate controllers, defoamers, 
shrinkage controllers, anti-oxidants and pigments. Examples 1 to A set 
forth one-part grout compositions of the present invention which can be 
used directly as a ceramic tile grouts. 
__________________________________________________________________________ 
EXAMPLE 1 
EXAMPLE 2 
EXAMPLE 3 
EXAMPLE 4 
Component Parts by wt. 
Parts by wt. 
Parts by wt. 
Parts by wt. 
__________________________________________________________________________ 
Acrylic latex 527.sup.1 
527.sup.1 
1125.sup.3 
1000.sup.2 
Aliphatic urethane dispersion 
100.sup.4 
100.sup.4 
240.sup.6 
130.sup.4 
Paraffin wax emulsion.sup.7 
20 20 100 20 
Water 73 73 73 73 
Calcium carbonate 
144 544 216 1000 
Silica 2171 1571 1200 1400 
Ammonium hydroxide 
0.25 
0.25 
0.25 
0.25 
Hydroxypropyl methyl cellulose 
1 1 1 1 
Biocide 12.5 12.5 12.5 12.5 
Propylene glycol 
73 73 73 73 
Surfactant 5 5 5 5 
Diluent 5 5 5 5 
Glycol ether 10 10 10 10 
Defoamer 1.25 
1.25 
1.25 
1.25 
Shrinkage controller 
195 195 200 195 
Titanium Dioxide 
34 34 34 34 
Anti-oxidant 24 24 24 24 
3396 3196 3320 3984 
__________________________________________________________________________ 
.sup.1 Ucar 422 manufactured by Union Carbide Corp. 
.sup.2 Unocal 1018 manufactured by Rohm and Haas 
.sup.3 Acronal S705 manufactured by BASF 
.sup.4 Spensol L54-MPW-32 
.sup.5 Neorez R9409 manufactured by Zencca 
.sup.6 Spensol L512 manufactured by Reichhold 
.sup.7 Aqua Bead 325E manufactured by Micro Powders, Inc. of New York 
Although a specific acrylic latex, aliphatic urethane and paraffin wax have 
been identified, other acrylic latexes, aliphatic urethanes and paraffins 
including paraffin oils can be used.

EXAMPLE 5 
Example 5 sets forth a liquid admix of the present invention which has been 
formulated for use with standard portland cement grout compositions. The 
admix is added to a typical grout formulation, such as a portland cement 
composition, in a ratio of 1 to 20 by weight to 1 to 30 by weight. 
______________________________________ 
Component Parts by wt. 
______________________________________ 
Acrylic latex.sup.1 70 
Aliphatic urethane dispersion.sup.4 
16.8 
Paraffin wax emulsion.sup.7 
6 
Water 70 
Surfactant 1.4 
Biocide 0.3 
164.5 
______________________________________ 
.sup.1, .sup.4 and .sup.7 as identified above. 
EXAMPLE 6 
______________________________________ 
Component Parts by wt. 
______________________________________ 
Acrylic latex.sup.2 1292 
Aliphatic urethane dispersion.sup.5 
380 
Paraffin wax emulsion.sup.7 
120 
Water 73 
Calcium carbonate 1071 
Ammonium hydroxide 0.25 
Hydroxypropyl methyl cellulose 
1 
Biocide 12.5 
Propylene glycol 73 
Surfactant 5 
Diluent 5 
Glycol ether 10 
Defoamer 1.25 
Shrinkage controller 200 
Titanium dioxide 34 
Anti-oxidanr 24 
3302 
______________________________________ 
.sup.2,5 and .sup.7 as identified above.