The present invention relates to improved compositions which are primarily useful in formulating floor finishes, and more particularly, to floor finishing formulations which include a novel water insoluble emulsion polymer that imparts improved performance characteristics (e.g., improved film gloss, leveling and recoatability) thereto. 
The term "floor finish" is used herein to designate products which are intended to be applied to floor surfaces of all kinds for protection, appearance, and cleanliness, which products adhere to the floor for a reasonable time and which may be removed periodically, as desired by the user.  The term includes waxes and wax-containing products as well as substitutes therefor, but excludes more or less permanent protective and decorative coatings such as paints, stains, varnishes, etc.  Floor finishes of the type in question are generally resistant to unintentional or accidental removal, particularly by water, while, at the same time, affording easy removal by readily available materials, such as, for example, "strippers" or other cleaning agents including alkaline soaps and detergents. 
Floor finish products of the type in question usually contain a water insoluble emulsion polymer component, a natural or synthetic wax component, and an alkali soluble resin, together with surface active agents used for wetting, emulsifying and dispersing, and a quantity of water sufficient to dilute the above solid components to a final solids content of from about 8 to about 45% in the finished product. 
Customarily, the emulsion polymer component is formed by emulsion polymerization, and the component thus formed is added to other previously emulsified components, including the resin and the wax, with the resulting product being sometimes further diluted to obtain the final intended solids content. 
In use, the product is applied to a clean floor, and spread about with a lambs wool applicator, sponge mop, or the like, and allowed to dry.  When the water evaporates, a continous polymer film remains.  In some cases, the product dries directly to a high gloss and in other cases, the film must be buffed to obtain a luster.  Products of the former type are commonly referred to as self-polishing floor finishes or "waxes" even though all such products do not necessarily contain natural wax. 
In evaluating an emulsion floor finish product, important properties which are usually evaluated are gloss, which, by reason of presenting a bright, clean appearance, make the product attractive; water and detergent resistance, which render the product capable of being rinsed or washed without being removed; recoatability, which permits addition of additional coats of the floor finish at intervals of days, weeks or even months after application of the original coating; and leveling, which relates to the ability of the composition to form a uniformly distributed coating without requiring great care in the application. 
A desired floor finish product of the type contemplated by the present invention is one which is easy to apply, which displays a high gloss, which displays excellent leveling, is highly resistant to removal by water and perhaps low power detergents, but which can be readily removed by stronger or more concentrated "stripper" materials, usually alkaline soaps or detergents.  An ideal product is also able to be buffed to a high gloss after rinsing.  Still further, such a product should be compatible with additional subsequent coatings of the same product rather than requiring removal of the old wax film before application of a new emulsion. 
While a number of compositions are known to be useful and effective in preparing emulsion polymers of the type described herein, and ultimately producing floor finish products from such polymers, there is still room for significant improvement in the formulation of emulsion polymers for this purpose. 
In view of the existing need for still further improved floor finish products and components thereof, it is an object of the present invention to provide improved chemical compositions suitable for making improved floor finish products. 
Another object is to provide a floor finish product which will provide a higher and more uniform gloss than that heretofore commonly achieved with emulsion floor finish products. 
A further object is to provide an emulsion type floor finish product having detergent resistance which is not substantially reduced in respect to the detergent resistance of counterpart prior art products. 
Another object is to provide an emulsion polymer which, when used as a component of a floor finish, provides improved recoatability, that is, a floor finish which may be applied over a pre-existing, dried film of the same product, even where the prior film has been in use as a floor coating for significant time. 
A still further object is to provide an emulsion polymer useful in making floor finishes which have improved leveling in relation to prior art products, that is, floor coating products which require less care in application and in which the film-forming constituents tend to achieve a highly uniform thickness by reason of their inherent flow characteristics. 
Another object is to provide an emulsion polymer product useful in making coating compositions having good water resistance and providing improved all-around combinations of gloss, detergent resistance, recoatability, and leveling, all without requiring additional plasticizer or other additives. 
Another object is to provide an aqueous polymer emulsion useful as a component of a floor finish composition, such aqueous polymer emulsion having a water-insoluble polymer component which is the emulsion polymerization reaction product of alpha methylstyrene, styrene and other conventionally used monoethylenically unsaturated monomers. 
The foregoing and other objects are achieved in practice by providing a floor finish composition and, in particular, an improved emulsion polymer component thereof.  This improved emulsion polymer component is combined as an aqueous emulsion polymer system with conventional wax, resin, and surfactant components to provide a floor finish having improved gloss, recoatability, and leveling, all without the sacrificing of detergent resistance or imposing a requirement of using additional or different plasticizers. 
The improved emulsion polymers of the present invention are copolymers of alpha methylstyrene and other monoethylenically unsaturated monomers which can be prepared by employing conventional emulsion polymerization techniques.  In particular, alpha methylstyrene is copolymerized with styrene and other monoethylenically unsaturated monomers conventionally employed in preparing emulsion polymers used in floor finish compositions.  Typical examples of such other monoethylenically unsaturated monomers include acrylic acid, methacrylic acid, esters of such acids (e.g., butyl acrylate, ethyl acrylate, methyl methacrylate, etc.),  acrylonitrile, methacrylonitrile and vinyltoluene (o, m or p).  Other such monoethylenically unsaturated monomers which can be used in preparing the improved emulsion polymers of the present invention are identified in U.S. Pat.  Nos.  3,328,325 and 3,766,112.  A preferred emulsion polymer of the present invention can be prepared by copolymerizing alpha methylstyrene, styrene, methyl methacrylate, butyl acrylate and methacrylic acid. 
The emulsion polymers of the present invention contain from about 5 to about 40% by weight alpha methylstyrene, from about 5 to about 40% by weight styrene, and from about 20 to about 90% by weight of the other monoethylenically unsaturated monomers referred to above, all such percentages being based on the combined weight of monomers charged.  Preferably, the combined amounts of alpha methylstyrene and styrene will equal about 40 to 60% by weight.  Particularly desirable emulsion polymers embodying the present invention are prepared by copolymerizing about 10 to 20 parts by weight of alpha methylstyrene with from about 20 to 30 parts by weight of styrene and a mixture of approximately 60 parts by weight of other monoethylenically unsaturated monomers.  In this regard, a superior emulsion polymer embodying the present invention is obtained by conventional emulsion polymerization techniques employing about 10 parts by weight of alpha methystyrene, about 28 parts by weight styrene, about 12 parts by weight methyl methacrylate, about 35 parts by weight butyl acrylate and about 13 parts by weight methacrylic acid.  While the final polymer solids concentration of the emulsion is not critical, dilution of the emulsion with water to provide a 15% by weight polymer solids concentration can be employed to provide a suitable emulsion component which is then added to the resin and wax components. 
In accordance with conventional practices, the improved emulsion polymers are prepared in the presence of suitable surface active agents or surfactants.  These surfactants enable the formation of a colloidal solution for the polymerization.  Typical examples of surfactants which can be employed include the alkyl aryl sulfonates, organo phosphate esters, sulfated esters of fatty acids, sodium dodecyl diphenyl disulfonates, dialkyl esters of succinic acid and other soluble anionic surfactants.  Also, nonionic surfactants may be employed such as, for example, the alkyl phenyl polyethoxy ethanols, organo silicones, fluorocarbon surfactants, and the like.  If desired, mixtures of such anionic and nonionic surfactants may be employed such as, for example, a mixture of the anionic surfactant, sodium lauryl sulfate, and the nonionic surfactant, nonylphenyl polyethylene glycol ether. 
The amounts of these surfactants used can vary from about 0.2% up to about 10% by weight based on the combined weights of monomer charged and surfactant with from about 1 to about 3% by weight of surfactant being preferred. 
As pointed out above, a typical floor finish or floor polish composition contains a polymer and wax portion, and an alkali soluble resin, together with wetting, emulsifying, and dispersing agents and water.  In the following examples, the makeup of the emulsion polymer portion of the floor finish compositions will be set forth in detail.  It will be understood that the completed floor finish product will contain from about 8 to about 45% solids, and preferably from about 10 to 20% solids.  The solids in the completed floor finish product comprise the polymer portion, the wax portion, and the resin portion together with the non-volatile or non-fugacious components of the surfactants, plasticizers, and the like. 
The ratio of emulsion polymer component to the wax component, based on the total of these components being 100%, is from 10 to 95% water insoluble emulsion polymer component, and from 5 to 90% natural or synthetic wax.  If the composition is intended to be self-polishing, the wax should not be over 35% by weight, preferably 5 to 25% by weight of the combined weight of the emulsion polymer plus wax.  If the composition is to be buffed rather than self-polishing, 35% by weight or more of the combined weights of the emulsion polymer and wax should be wax. 
The wax component may be of any of a number of natural waxes or synthetic waxes, or mixtures thereof, known to those skilled in the art, including waxes of a vegetable, animal, synthetic, and/or mineral origin such as carnauba, candelilla, montan, lanolin, cocoa butter, cottonseed, Japan wax, bayberry, mrytle, mace, palm kernel, beeswax, spermaceti, Chinese insect, mutton tallow, polyethylene, polypropylene, waxes obtained by the hydrogenation of coconut oil or soybean oils, and the mineral waxes such as paraffin, ceresin, ozokerite and the like. 
In the finished composition, the alkali-soluble resin component may comprise up to 40% of the total of the emulsion polymer and wax component, while the wetting, emulsifying, and dispersing agents may comprise from 0.5 up to 20% by weight of the total of the emulsion polymer, wax, and resin components.  Preferably, the alkali soluble resin component represents some 10 to 30% of the weight of the solids present in the final floor finish composition. 
The alkali-soluble resins typically used include rosin acid, maleate-modified rosin acid ester, shellac, styrene-maleic anhydride copolymers, polyesters, alkali soluble alkyds, pentaerythritol esters of rosin, manilla gum, Loba gum and the like.  The selection of the exact materials used may vary widely.  The emulsion polymers of the present invention are compatible with a large number of such resins, and the exact selection of such resins is a familiar matter to those skilled in this art .