Multi-Layered Liquid Detergent-Builder Concentrate Compositions Which on Addition to Water Produce Stable Cleaning Solutions

The present invention relates to detergent or cleaning concentrates especially adapted for single-use applications.

Generally speaking, in formulating liquid detergents and cleaners to provide an end product which is homogeneous in appearance, the ability to concentrate the ingredients comprising the formulation is limited by the degree of compatibility of the ingredients. Typically, conventional formulation approaches involve, for example, dissolving organic surfactants and inorganic builder components in aqueous media using coupling solvents and/or hydrotropes to attain a homogeneous and stable dispersion of the ingredients. This practice can give rise to problems because the organic surfactants tend to "salt out" of solution due to the presence of the alkaline inorganic salts employed in the builder. Thus, even when cosolubilizing agents are used, there is a critical upper limit as to the quantity of the functional components which can be maintained in dispersion in the end product. In a sense, there is what might be called a "compatibility barrier" in the conventional formulation of liquid detergents and cleaners. A formulator, therefore, has considerable difficulty in utilizing larger concentrations of the more active components. Wholly apart from the ingredient incompatibility and concentration of ingredient problems encountered with conventional formulating practices, such practices have important economic disadvantages, chief among which are the need for cosolubilizing agents, and the comparatively large volumes of water required to attain a homogeneous end product. In this latter connection, it should be noted that typical liquid detergent and cleaning formulations contain 50%, or more, water, while the active surfactant content is of the order of 16%, or less. Cosolubilizing agents such as coupling solvents and hydrotropes, of course, represent an added raw material cost, while the need for appreciable volumes of water adds to the material handling costs and at the same time entails the use of containers, or packaging, of a correspondingly larger size to accommodate the end product.

In accordance with the present invention, a system has been evolved for providing liquid detergents and cleaners in a highly concentrated form which eliminates the need for cosolubilizing agents and large volumes of water. The resulting significant savings in starting material and material handling costs are augmented by the fact that the system enables smaller and less costly containers, or packaging, to be used to hold the concentrates. What is more, the systems provide stable, ready-to-use solutions which not only are less costly on a unit volume basis than is the case with conventional homogeneous cleaning solutions, but, also, show surprisingly improved cleaning efficiency on a unit volume basis over homogeneous solutions.

The system of the present invention is especially adapted for single-use applications to provide a substantially homogeneous, dilute solution or dispersion of predetermined composition to be used for detergent, cleaning, or the like, purposes. The system comprises a fluid-tight container having at least two separate layers of liquid compositions therein, one of the layers comprising, as an essential ingredient, a predetermined quantity of a concentrate of at least one surfactant which is soluble or readily dispersible in a diluent such as water. Another of the layers in the container advantageously comprises, as an essential ingredient, a solution or dispersion, in the form of a concentrate, which incorporates a predetermined quantity of at least one detergent builder. The compositions of the separate layers in the container are of a character such that, if mixed together in their concentrated form, they would be incompatible or immiscible, and the resulting mixture would be non-homogeneous. The compositions of the separate layers, however, are so related as to the components, or ingredients, and proportions thereof that when essentially all of the liquid contents of the container are poured into a predetermined quantity of a diluent such as water, a final, essentially stable solution or dispersion is obtained in ready-to-use form. In marked contrast to typical homogeneous formulations, the active surfactant concentrate portion of the system, in most instances, will contain less than 10%, usually 4 or 5%, of water, and, in other cases, depending upon the nature of the ingredients employed, will contain no added water. The system can be formulated to provide, in ready-to-use form, stable solutions useful as hard surface cleaners, degreasers, bowl cleaners, floor wax removers, liquid dishwashing detergents, commercial or household heavy duty laundry liquids, concentrated liquid hand soaps, carpet shampoo concentrates, high strength metal cleaners, car wash concentrates, and the like.

In accordance with a preferred embodiment of the invention, the system comprises a water soluble surfactant concentrate layer component and a water soluble builder concentrate layer component packaged in a suitable, flexible or rigid plastic liquid-tight container. Generally speaking, the ingredients employed in formulating the surfactant concentrate layer will be dependent upon the use to which the finally produced stable, ready-to-use solution is to be put. Thus, for example, if the solution is to be used as a hard surface cleaner, the surfactant concentrate layer will advantageously comprise as an essential ingredient a major proportion of a water soluble nonionic surfactant or a compatible mixture of nonionic surfactants. On the other hand, if, for example, the ready-to-use solution is to be employed as a degreaser, the surfactant concentrate layer desirably will comprise a major proportion of a compatible mixture of water soluble nonionic, anionic, cationic or amphoteric surfactant materials or a mixture of nonionic and anionic surfactants.

Exemplary of water soluble nonionic surfactants useful for the purposes of this invention are polyglycol esters of higher straight and branched chain aliphatic alcohols and polyglycol esters of higher fatty acids, in which the alcohol group and the fatty acid group, respectively, comprises 8 to 20, or more, carbon atoms and which contain 10 to 50 ethylene oxide units per molecule. Especially preferred nonionic surfactants are the water soluble condensates of alkylphenols such as octyl- or nonylphenol with from about 5 to about 15 moles of ethylene oxide. Also useful are the numerous compounds obtained from the reaction of alkanolamines and fatty acids, and the ethylene oxide condensates thereof.

Water soluble anionic surfactants which can be used include alkyl aryl sulfonates, in particular alkylbenzene, especially linear monoalkyl benzene, sulfonates in which the alkyl group contains from 8 to 20 carbon atoms, specific examples being n-dodecylbenzene sulfonate and n-octadecylbenzene sulfonate; higher aliphatic sulfates and sulfonates in which the aliphatic radical comprises from 8 to 20 carbon atoms such as lauryl sulfate or lauryl sulfonate; and higher fatty acid amides in which the acyl group contains from 8 to 20 carbon atoms such as tallow fatty acid amide, cocoa fatty acid amide, and the like. The sulfates and sulfonates are commonly used in the form of alkali metal salts, although the corresponding salts of ammonium or organic bases such as ethanolamine, triethanolamine, and the like may also be used.

Cationic surfactants useful in formulating the surfactants concentrate layer of the system include quaternary ammonium salts represented by the formula: ##STR1## where: R.sub.1 is hydrogen, alkyl or alkylol; R.sub.2 and R.sub.3 are lower alkyl or alkylol, or aryl or aralkyl; R.sub.4 is a long chain alkyl radical containing from 8 to 22, preferably 12 to 15 carbon atoms in straight or branched chain arrangement, with or without aryl or alkaryl substituents; and A is an anion such as halogen, sulfate, acetate, hydroxyl, or the like. Specific examples of such salts are cetyl-dimethyl-benzyl-ammonium chloride, didodecyl-benzyl-methyl ammonium chloride and dodecyl-dimethylethylbenzyl ammonium chloride, to mention a few. Another group of quaternary substituted ammonium compounds which can be used are heterocyclic derivatives wherein N is an element in a heterocyclic ring. Typical of this group are lauryl morpholinium, imidazolium, pyridinium and quinolium compounds specific examples of which are N-benzyl-N higher alkyl morpholinium chloride and N-laurylmethyl pyridinium chloride.

Amphoteric surfactants which can be used to formulate the surfactant concentrate layer of the system include betaine and various betaine compounds such as coco betaine, tallow betaine, cocoyl amido propyl betaine, laurylamidipropyl betaine, to mention a few. Also useful as amphoterics are substituted imidazolines exemplified by mono- and dicarboxyl coco imidazoline, lauryl imidazoline, coco imidazoline, and the like.

The active surfactant ingredient, that is, the nonionic, anionic, cationic or amphoteric surfactant, or a compatible mixture thereof, employed in preparing the surfactant concentrate layer of the system comprises, as indicated hereinabove, a major proportion of the layer. The generally optimum objectives of the invention are attained with active surfactant concentrations of from about 50% to upwards of about 99%, by weight, of the surfactant concentrate layer. The finished surfactant concentrate layer desirably includes minor amounts of materials which will make the stable, ready-to-use solution prepared from the system of the present invention more effective and more attractive. The following are mentioned by way of example. A defoamer such as silicone and silicone emulsions, and fluorescers, perfumes and dyes. The concentration of such additives in the layer will range from about 0.01% to about 8 or 10%, by weight of the concentrate. Other additives, of course, can be used without departing from the spirit and scope of the invention.

The ingredients employed in formulating the water soluble builder concentrate layer of the system, for optimal results, will be dictated in large measure by the composition of the surfactant concentrate layer. As indicated hereinabove, the surfactant concentrate layer and the builder concentrate layer are of a character such that, if mixed together in their concentrated form, they would incompatible or essentially immiscible, and the resulting mixture would be non-homogeneous. However, the ingredients comprising each layer are so related with respect to their functional properties and their proportions in the layers that when both layers are poured into a predetermined volume of a diluent such as water, a final essentially stable detergent or cleaning solution, or dispersion, is produced in ready-to-use form.

By way of illustration, in formulating a builder concentrate layer for use with a surfactant concentrate layer intended for producing a stable detergent or cleaning solution for use as a hard surface cleaner, the active ingredients of the builder concentrate layer will advantageously comprise an alkali metal builder salt such as sodium or potassium carbonate, an aqueous solution of an alkali metal hydroxide exemplified by a 50% solution of potassium or sodium hydroxide, and a soluble aminopolycarboxylate salt such as an alkali metal salt of ethylenediaminetetraacetic acid. In formulating a builder concentrate layer for use with a surfactant concentrate layer to produce a ready-to-use solution to serve as a degreaser, the builder layer desirably will be formulated to include a polybasic organic acid such as citric acid, or an alkali metal salt of such an acid, an aqueous solution of an alkali metal hydroxide, an aminopolycarboxylate salt, and a small amount of a stabilizer such as polyvinyl pyrrolidone. Sufficient water is added to maintain the active ingredients comprising the builder concentrate layer in solution. Generally speaking, the proportion of active materials in the builder concentrate layer will range from about 20% to about 80%, usually about 30% to about 40%, by weight, of the aqueous concentrate builder layer.

Other alkali metal builder salts which can be used in formulating the builder concentrate layer include alkali metal phosphates, sulfates, and silicates exemplified by disodium orthophosphate, sodium metaphosphate, sodium tripolyphosphate, sodium sulfate and sodium silicate, to mention a few. The corresponding ammonium salts also are useful. Exemplary of aminopolycarboxylate salts which can be used are the sodium, potassium and alkanolammonium salts formed with ethylenediaminetetraacetic acid, N-(2-hydroxyethyl)ethylenediaminetetraacetic acid and nitrilotriacetic acid. In addition to the foregoing, amine salts, alkali metal salts and ammonium salts of gluconic acid can be incorporated into the builder concentrate layer to reduce possible skin irritation.

The volume ratio of surfactant concentrate layer to builder concentrate layer of the system of the present invention can range from about 1:9 to 9:1, again depending upon the end use of the stable solution produced by the system. The total volume of the concentrated layers in the container comprising the system can vary widely, again, depending upon the final use-dilution volume required. Generally speaking, for most purposes, the total volume of the concentrate layers will be of the order of 1 to 2 ounces up to a gallon for large scale cleaning operations. The use-dilution ranges, that is, the amount or volume of diluent such as water to be used in producing a stable ready-to-use solution with the concentrates comprising a particular system also will depend upon the end use of the solution. In broad terms, the use-dilution ranges for good performance will be of the order of about 1 of the concentrate system to about 30 to about 500 of water.

The fluid-tight containers comprising the system may be fabricated of glass or plastic. For average cleaning jobs, the containers advantageously will be in the form of a flexible, single-use bag or packet made of a thermoplastic sheet material such as polyethylene. Heat sealable containers of this type will contain from about 1 or 2 to about 6 ounces of the concentrate layers, and, while resistant to tearing, can be readily opened. The concentrate layers can be injected into the bag or packet, and the bag or packet heat sealed, with conventional equipment.

The following compositions are illustrative of the system of the present invention. The percentages are given on a weight basis.

In order to demonstrate the improved cleaning efficiency of stable detergent or cleaning solutions or dispersions produced with the systems of the present invention over the cleaning efficiency of conventional homogeneous detergent or cleaning solutions, as well as to show the cost advantages afforded by the systems over conventional homogeneous solutions, comparative performance/cost tests were carried out using an all-purpose cleaner prepared with a system of this invention and a conventional all-purpose cleaner.

Table I gives the formula, cost data, and the cleaning efficiency at use-dilution for an all purpose cleaner produced from a system of the invention. At a dilution ratio of 1/256, the cleaning efficiency (C.E.) of this formulation was 80 percent and the cost of chemicals for one gallon of this use-dilution was $0.0114. Comparative data for a homogeneous formulation, using the same raw materials plus solubilizers (hydrotropes or solvents), are given in Table II. The homogeneous formulation required a 1/20 dilution to yield a C.E. of 77.5% at a cost of $0.0602/use-dilution gallon. Thus, a homogeneous preparation had to be 12.8 times more concentrated at use-dilution to yield similar cleaning, and this costs approximately six-times more than the system of this invention.

The cleaning efficiencies reported in the preceding tables were derived using a standard washability test. This test methodology is a modified form of Federal Test Method Standard No. 536/670. The methodology used is given below:

I. Panel Preparation

1. Read reflectance of white tile * with Photovolt Meter (Rf=67.5)

2. Soil panels with standard soil (from federal test standard method) using a 5 mil. film applicator.

3. Allow panels to age overnite (use within 1 week at most).

II. Washing of Panels

1. Make up 200 ml of use dilution cleaning solution for each tile (run 2 tiles per solution).

2. Apply 50 ml to sponge in sponge holder. Pour remaining 150 ml. to sponge in sponge holder. Pour remaining 150 ml over panel which is clamped into the tray of the Gardner washability apparatus.

3. Soak panel in solution for 60 seconds.

4. Run sponge over panel for 50 cycles (100 strokes).

5. Remove panel and rinse off residue with tap water.

6. Dry for at least 30 minutes.

III. Calculation of Cleaning Efficiency (C.E.)

1. Set Photovolt Meter to 75% Rf with the green filter inserted.

2. Read reflectance of panel at 3, 6, and 9 inches from top of panel. Calculate average of these 3 numbers=Rf soiled.

3. Calculate C.E. by using equation Rf soiled/67.5.times.100=C.E. %