Sulfuric acid has been used to clear drains of many organic materials, including fats, hair, paper, cotton, tea, coffee grounds and tobacco, as well as some inorganic materials such as chalk, hard water salts, lime scale and iron scales. The properties of sulfuric acid which make it effective for drain cleaning include: (1) its high heat of dilution in contact with residual water in the drain which melts fats, greases and low melting point compounds that otherwise act as clogging sites for other debris; (2) its reactivity with a wide range of function groups such as hydroxyl, carbonyls, esters, unsaturated bonds, rings and amino groups; and (3) its high dissociation constant that helps dissolve many organic and inorganic materials. Notable examples of use of sulfuric acid to clean drains are U.S. Pat. Nos. 3,538,008 to Ancel et al. and 4,096,871 to Vlahakis.
Unfortunately, sulfuric acid will not affect polystyrene. Consequently, it is desirable to combine sulfuric acid with a polystyrene solvent in a single drain cleaning drain cleaning system. However, many polystyrene solvents are reactive with sulfuric acid and they have not previously been employed together in a stable two-phase drain cleaning composition.
Previous drain cleaning compositions and processes that utilize hydrocarbon solvents include U.S. Pat. Nos. 3,553,145 and 3,553,146 to Butke et al., 3,666,670 to Gilbert et al., 3,576,751 to Noznick et al., and 3,060,125 to Sims. None of the disclosed compositions use halogenated hydrocarbon solvents specifically for dissolution of polystyrene.
The Diphase Drain Cleaner patent application identified above was primarily directed to halogenated aromatic hydrocarbon polystyrene solvents. The present application is, in comparison, directed to halogenated aliphatic hydrocarbon polystyrene solvents.
It is an object of the present invention to provide an improved two layer composition for diphase cleaning of a drain utilizing selected halogenated aliphatic polystyrene solvent.
It is another object of the present invention to provide a method of cleaning a drain using a diphase composition of sulfuric acid and selected halogenated aliphatic polystyrene solvents.
Description of the Invention
I have discovered that certain organic solvents and solvent blends will not be attacked by sulfuric acid. These solvents form a layer above sulfuric acid and dissolve polystyrene while not being affected by, or having an affect upon sulfuric acid. A stable diphase composition is formed. Further, the two layers produce a synergistic effect. The heat produced by the sulfuric acid reacting with water present in the drain drastically increases the polystyrene dissolving powers of the solvent layer. The solvent layer also acts to wash down the sides of the drain as the drain blockage is removed and to act as a "cover" for unwanted smells from sulfuric acid reaction products.
The composition of the invention consists of two mutually immiscible liquid layers. The lower and denser layer makes up from 50 to 99 percent of the total composition weight and consists of at least 20 percent sulfuric acid solution. The preferred composition uses 93 percent sulfuric acid solution for the lower layer.
The sulfuric acid solution should be of sufficient concentration and volume to make a sulfuric acid solution of at least 10% concentration after dilution with water in the drain. Normally, about four ounces of water will sit above a clogged drain. Therefore, a minimum amount of four ounces of at least 25% sulfuric acid solution is required. Of course, less volume of a more concentrated solution would be necessary.
The upper less-dense layer makes up from 1 to 50 percent of the total composition weight and consists of selected halogenated aliphatic hydrocarbon polystyrene solvents such as carbon tetrachloride; dichloroethane; trichloroethane; trichloroethylene; dichloropropane; tetrachloroethane; pentachloroethane; and perchloroethylene. The invention contemplates the upper layer composed of any of these substances or a combination of two or more of the substances.
The upper less-dense layer may include saturated aliphatic hydrocarbons to reduce the necessary amount of halogenated aliphatic hydrocarbon in that layer. Substances such as mineral oil and mineral spirits, containing saturated cyclic hydrocarbons, are adequate for this purpose. The upper layer can be up to 99% by weight saturated hydrocarbons, being up to almost 5% of the total composition weight. At least 1% by weight of the upper layer should be any of the halogenated aliphatic hydrocarbons listed above or any combination thereof. That is, the active ingredients in the upper layer are the halogenated aliphatic hydrocarbons which should make up at least 0.01% of the total composition weight.
A preferred composition consists of a lower layer being 95% of total composition weight and consisting of 93% sulfuric acid solution. A solvent blend makes up the upper layer, being 5% of the total composition weight. The solvent blend is composed of equal amounts of weight of the halogenated aliphatic hydrocarbon and the saturated aliphatic hydrocarbons. Alternatively, the solvent blend may vary from 95% by weight saturated hydrocarbons and 5% by weight halogenated aliphatic, to 100% by weight halogenated aliphatics.
The particular polystyrene solvents used in the upper layer blend were selected because of two criteria: (1) they must be stable in contact with concentrated sulfuric acid; and (2) they must be effective polystyrene solvents when in a layer above concentrated sulfuric acid. In order to determine which solvents meet these criteria, stability and effectiveness studies were conducted.
Stability Study
The following results were obtained for storage of five cubic centimeters of a candidate solvent in a layer above and in contact with ninety/five cubic centimeters of concentrated sulfuric acid (93%) at room temperature in glass containers.
Additional stability data was obtained for storage of five cubic centimeters of the candidate solvent in a layer above and in contact with ninety-five cubic centimeters of 84% sulfuric acid solution at 100.degree. F. in glass containers. The results are set forth below.
Effectiveness Study
The study of the effectiveness of candidate solvents in a layer above sulfuric acid for dissolving polystyrene was conducted using the following procedure:
(1) A Pyrex measuring cup was placed on an acid resistant surface;
(2) An empty polystyrene drinking cup was placed in the center of the Pyrex container;
(3) The following items were placed in the polystyrene cup:
a paper towel
a teaspoon of Crisco
a piece of Kotex
a tea bag
a cigarette or cigarette butt;
(4) The polystyrene cup was filled about half way with water; and
(5) The solvent-acid system was added to the contents of the polystyrene cup.
The results of these tests are summarized below:
Additional ingredients such as a corrosion inhibitor, dye or stable fragrance may be added to make the composition more commercially desirable.
Drains are cleaned by the diphase composition in a unique manner. The denser sulfuric acid layer comes in contact with water and the drain blockage. It melts and dissolves fats, hair, paper, cotton, tea, coffee grounds and tobacco, chalk, hard water salts, lime scale, iron salts, and other organic and inorganic substances which may cause drain blockage. Polystyrene material in the drain blockage is not affected by the sulfuric acid but will be released from the drain blockage as the other substances are melted and dissolved. The free polystyrene will float to the upper less-dense layer of halogenated aliphatic hydrocarbons where it is dissolved. Although the density of the sulfuric acid solution will vary with its strength, it will normally be denser than the halogenated aliphatic layer and will, consequently, be the lower layer in the composition. This guarantees initial contact of the sulfuric acid with the drain blockage.
The following examples demonstrate possible diphase drain cleaning compositions.
Example I
95% by weight 93% sulfuric acid is combined with 5% by weight carbon tetrachloride to produce a two layer composition.
Example Ii
60% by weight 40% sulfuric acid is combined with 20% by weight of 1,1,1-trichloroethane and 20% by weight of saturated aliphatic hydrocarbons to form a two layer composition for cleaning drains.
Example Iii
50% by weight 80% sulfuric acid is combined with 49.75% by weight saturated aliphatic hydrocarbons and 0.25% by weight pentachloroethane to produce a diphase drain cleaning composition.
While the invention presently disclosed is considered to be the preferred embodiment of the invention, it is understood that changes, modifications and substitutions may be made therein without departing from the true scope of the invention as defined in the claims.