Drain cleaner

A drain cleaner composition of reduced toxicity comprises an organic solvent, preferably a water soluble solvent, a surfactant, preferably a fluorosurfactant, a hair decomposer such as a thioglycolate salt, a water soluble salt for increasing the density of the formulation, a thickener to increase the viscosity of the formulation. The composition is preferably formulated as an aqueous solution and other ingredients of reduced toxicity such as accelerators for hair decomposition, corrosion inhibitors, fragrances and dyes may also be included.

FIELD OF THE INVENTION 
This invention relates to drain cleaners, that is, to materials which are 
used for cleaning blocked drains by the introduction of a chemical cleaner 
into the drain. 
BACKGROUND OF THE INVENTION 
Drains for household sinks often become clogged by a combination of fatty 
substances, protein or cellulose fibers and soap. Although soap is a good 
detergent, it has the disadvantage that it reacts with divalent metallic 
ions in water such as calcium and magnesium, to form an insoluble curd. 
This curd, together with small amounts of fatty substances such as oil, 
grease, fatty substances from the body, cooking oils or even hair grooming 
products, tends to adhere to the inside of the drain and forms a 
restriction to the free flow of water. In addition, solid, water insoluble 
products such as hair, lint or paper may become lodged in the drain at the 
point of restriction so that a relatively immovable plug is eventually 
formed in the drain. 
Most conventional drain cleaners are composed of concentrated solutions of 
strong acids such as sulfuric acids or of bases such as sodium hydroxide 
or combinations of strong oxidizing agents with strong bases. Cleaners of 
this kind attack the clogging material lodged in the drain at the 
restriction and are generally effective in removing the plug but they have 
the disadvantage that they are extremely dangerous materials, especially 
for household use. Each year, a considerable number of accidents occur 
with drain cleaners of this kind, either from the cleaner being splashed 
onto the skin or by small children ingesting inadequately guarded 
quantities of the cleaner. It would therefore be desirable to develop a 
relatively less toxic cleaner which would still be effective for removing 
the blockages in most household drains. 
Various combinations of chemical ingredients have been proposed for drain 
cleaners, with different objectives. For example, U.S. Pat. No. 3,965,048 
discloses a drain cleaner composition which is stated to be effective in 
dissolving soap curd and which contains salts of certain polyamine 
polycarboxylic acids together with other ingredients such as surfactants, 
and ingredients such as urea and thyoglycolate salts which are effective 
in dissolving hair and other water insoluble objects. U.S. Pat. No. 
4,206,607 also discloses drain cleaner compositions which are effective in 
dissolving soap curd and which, besides containing salts of certain amino 
acids and anionic surfactants, may also contain corrosion inhibitors such 
as thioglycolate salts and materials such as urea which are capable of 
promoting the dissolution of hair and other insoluble materials. U.S. Pat. 
No. 4,206,068 discloses drain cleaner compositions which are based on a 
redox system together with a relatively large amount of a caustic alkali 
such as sodium hydroxide. Upon use in the drain, the redox system develops 
a substantial amount of heat upon dissolving in the standing water in the 
drain and this assists dissolution of hair and fatty substances making up 
the plug. U.S. Pat. No. 2,997,444 discloses a drain cleaning composition 
based on caustic alkali and an anticlogging agent such as sodium sulfide 
or sodium thioglycolate. 
We have now developed improved drain cleaner compositions which are 
relatively less toxic than the drain cleaners which are presently 
commercially available and yet which are still effective in unplugging 
drains clogged with soap, grease and hair or other insoluble materials. 
SUMMARY OF THE INVENTION 
According to the present invention, the drain cleaners comprise the 
following ingredients in combination: 
(i) An organic solvent, 
(ii) A thioorganic compound which decomposes protein fibers such as hair, 
(iii) A surfactant, 
(iv) A water soluble densifying salt, and 
(v) A water soluble thickener. 
In addition, additional materials such as corrosion inhibitors, ingredients 
such as urea which help to dissolve protein fibers, sequestering agents, 
corrosion inhibitors, fragrances and dyes for consumer sensory appeal and 
other conventional adjuvants for drain cleaners may also be present in 
these formulations. 
The drain cleaner's composition is most conveniently formulated for 
commercial sale as an aqueous solution so that the product may be readily 
introduced into blocked drains without the necessity for the user to 
dissolve the various ingredients. Formulation as a solution also ensures 
homogeneity of composition.

DETAILED DESCRIPTION 
The drain cleaners according to the present invention, are compositions 
which are formulated to be relatively less toxic than currently available 
drain cleaners and yet are still effective in unplugging drains which are 
clogged with soap, oil, grease, hair and other protein fibers and possibly 
other water insoluble materials such as lint or paper. Because the 
cleaners do not contain any strongly acidic or alkaline ingredients or any 
other materials with a prompt injurious effect upon human tissues or the 
human system, they are relatively safe in use; the preferred compositions 
have a relatively low toxicity and in favorable cases, the LD.sub.50 dose 
for human adults may be as much as about 500 ml (about 1 pint). Because 
they do not contain corrosive ingredients, any unintended ingestion may be 
remedied by the use of conventional emetics or other appropriate first aid 
measures. 
The drain cleaner compositions are, as previously mentioned, conveniently 
formulated as aqueous solutions but if certain ingredients, e.g. the 
organic solvent, are relatively water-insoluble, the composition may be 
formulated as an emulsion or a dispersion, since the surfactant which is 
present will help to promote stability of the emulsion or dispersion. In 
such cases, however, it may be desirable to increase the amount of 
surfactant in order to ensure that sufficient amount thereof is also 
present for the dissolution of oil and grease in the drain clogging 
material. The compositions are preferably formulated as solutions in order 
to ensure homogeneity in production and upon use. 
The compositions include an organic solvent which is effective for 
dissolving grease and soap scum and curds commonly found in clogged 
drains. A wide range of organic solvents may be used but is it preferred 
to use solvents of low environmental toxicity, particularly those which 
are relatively non-toxic to human beings. Furthermore, the preferred 
organic solvents are water soluble solvents such as certain lactones, 
pyrrolidinones and their substituted derivatives, e.g. 
gamma-butyrolactone. 
The preferred organic solvent is N-methyl-2-Pyrrolidinone which is an 
active organic solvent of relatively low human toxicity, especially at the 
dilution levels found in the present compositions. It is effective for 
dissolving the grease and soap scum and curds commonly found in clogged 
drains and this, coupled with its low toxicity and water solubility makes 
it a preferred ingredient in this class. The amount of organic solvent is 
generally from 5 to 20, preferably 5 to 15, weight percent of the total 
composition. At these concentrations of the preferred solvents, it has 
been found that the compositions do not dissolve PVC plumbing systems to 
any significant extent at about 24 hours exposure and similar results with 
polyolefin systems would be expected. 
The compositions also include an organic sulfur compound which is effective 
to dissolve protein fibers such as hair since this is the material most 
commonly found in clogged residential bathroom drains. The thioorganic 
compounds of this kind are known as depilatories and are frequently used 
in cosmetic creams and cold wave formulations for effecting a total or 
partial decomposition of human hair. The preferred materials of this type 
are the salts of mercaptocarboxylic acids, especially the salts of 
mercapto-acetic acid (thioglycolic acid) or 2-mercaptopropanoic acid 
(thiolactic acid). The alkali metal salts, especially the sodium and 
potassium salts, the ammonium, alkylamine, hydroxyalkylamine and 
alkylammonium salts and the alkaline earth salts of these acids, 
especially of thioglycolic acid are particularly preferred. Generally, 
sodium thioglycolate will be the preferred ingredient of this class from 
the point of view of efficiency and economy. The amount of the thioorganic 
compound will generally be from 1 to 10%, preferably 1 to 5%, of the total 
composition. Because these thioorganic compounds will generally be the 
most toxic of the constituents in the drain cleaner, the amount should 
preferably be limited to that necessary for dissolving hair and other 
protein fibers, generally to below 5 percent. However, if increased 
toxicity can be permitted, more may be used to ensure dissolution of hair 
clots. 
A surfactant is included in the composition to aid in the dissolution of 
oils and greases as well as to ensure that fine particulate materials 
remain in suspension. Again, surfactants should preferably be selected 
from the point of view of human toxicity, those of low toxicity being 
preferred. The surfactants may be anionic, cationic or non-ionic or 
amphoteric and combinations of these different types of surfactants may be 
used if desired. 
Anionic surfactants are typically organic compounds containing carboxolate, 
sulfonate, sulfate or phosphate polar solubilizing groups, generally in 
the form of their sodium, potassium, ammonium or substituted ammonium 
salts. Exemplary classes of anionic surfactants are the metal or ammonium 
carboxolates of C.sub.9 to C.sub.21 straight chain carboxylic acids, 
carboxylates with fluorinated alkyl chains, e.g. those marketed under the 
trademark Fluorad by the 3M Company and other fluorocarboxylates 
containing fluorinated and perfluorinated alkyl chains. In general, 
replacement of hydrogens on the hydrophobic portion of the molecule by 
fluorine atoms leads to surfactant molecules of unusually low surface 
tension and effectiveness and for this reason surfactants of this kind are 
preferred. Other anionic surfactant types include the 
polyalkoxycarboxylates, the N-acylsarcosinates, sulfonates, especially the 
alkylbenzene sulfonates, particularly those with linear alkyl side chains 
in the form of their sodium or ammonium salts and petroleum sulfonates 
produced by the sulfonation of high boiling petroleum feedstocks. 
Sulfates, such as the alcohol sulfates, e.g. sodium lauryl sulfate, sodium 
2 ethylhexyl sulfate, sodium decyl sulfate, ethoxylated and sulfated 
alcohols and esters of ortho phosphoric acid are other typical anionic 
surfactants. 
Cationic surfactants, which form a positively charged solubilizing group 
when dissolved in water are generally amino or quaternary nitrogen 
compounds, usually with low molecular weight alkyl groups such as methyl 
or hydroxyethyl to confer increased water solubility. Typical cationic 
surfactants include amines such as the aliphatic mono- , di- and 
polyamines derived from fatty and rosin acids, e.g. the 
N-alkyltrimethyline diamines where the alkyl group is derived from 
coconut, tallow or soybean oils; the amine oxides, ethoxylated alkylamines 
and alkoxylates of ethylene diamine, amino amines containing amide 
linkages connecting the amino group to hydrophobes, e.g. tall oil fatty 
acid diethylene diamines and polyalkylene polyamine condensates (other 
oils from which these may be derived include coconut oil, oleic acid and 
stearic acid) and quaternery ammonium salts such as the dialkyl dimethyl 
ammonium salts where the alkyl group contains about 10 to 20 carbon atoms. 
Generally, it is preferred not to use cationic surfactants in combination 
with anionic surfactants since reaction of the two large, oppositely 
charged ions tends to produce a salt that is insoluble in water although 
ethoxylation of either component will moderate this tendency. 
Non-ionic surfactants which form hydrophobes carrying no discreet charge 
when dissolved in aqueous media may be included, for example, the 
polyoxyethylene surfactants such as the polyethoxylated aliphatic 
alcohols, alkylphenols and carboxylic acid esters, e.g. the 
polyoxyethylene esters of long chain fatty acids such as lauric acid, 
stearic acid, oleic acid and tall oil and coco fatty acids. Amphoteric 
surfactants may also be employed. 
A particularly preferred class of surfactants are the fluorosurfactants 
which, as a class, are notable for their excellent wetting action, their 
chemical and thermal stability as well as their effectiveness at very low 
concentrations. They may be anionic, cationic, nonionic or amphoteric but 
a preferred type within this class comprises the ethoxylated alcohol type 
containing a perfluoroalkyl group of about 6 to 16 carbon atoms. 
Surfactants of this type have the typical general formula: 
EQU F(CF.sub.2 CF.sub.2).sub.3-8 CH.sub.2 CH.sub.2 O(CH.sub.2 CH.sub.2 O).sub.n 
H 
where n indicates the degree of ethoxylation. Other fluorosurfactants 
include the anionic types such as the phosphate esters, e.g. of the 
formula: 
EQU (R.sub.f CH.sub.2 CH.sub.2 O).sub.1,2 P(O)(OX).sub.2,1 
where R.sub.f is F(CF.sub.2 CF.sub.2).sub.3-8 and X is H, NH.sub.4 etc. and 
carboxylate types such as 
EQU R.sub.f CH.sub.2 CH.sub.2 SCH.sub.2 CH.sub.2 CO.sub.2 M 
where R.sub.f is as before and M is an alkali metal, especially lithium. 
Cationic fluorosurfactants, e.g. quaternary ammonium compounds such as 
EQU R.sub.f CH.sub.2 CH.sub.2 SCH.sub.2 CH.sub.2 N.sup.+ 
(CH.sub.3).sub.3.CH.sub.3 SO.sub.4 - 
and amphoteric types such as 
EQU R.sub.f CH.sub.2 CH(OCOCH.sub.3)CH.sub.2 N.sup.+ (CH.sub.3).sub.2 CH.sub.2 
CO.sub.2 - 
are also highly effective surfactants in this class. Surfactants of these 
types are commercially available under the Zonyl trademark from DuPont. 
The surfactant is used in an amount sufficient to assist the dissolution of 
oleaginous components of the drain clogging materials and to maintain 
these materials in suspension following their dissolution. Generally, the 
amount of surfactant will be from 0.1 to 5%, preferably 0.1 to 2%, of the 
total composition, although these typical amounts will, of course, vary 
according to the effectiveness of the surfactant used. As mentioned above, 
the fluorosurfactants are particularly preferred since they are effective 
at very low levels of use and it has been found that less than 1%, e.g. 
0.3 to 0.5%, of the preferred fluorosurfactants may be effective. The 
fluorosurfactants are also preferred because they work synergistically 
with organic solvents such as the preferred N-methyl-2-pyrrolidinone and 
the thioorganic compounds used to decompose the protein fibers, especially 
sodium thioglycolate. 
A water soluble salt which increases the density of the drain cleaner 
composition is also used. Generally, this will be sodium chloride although 
other water soluble salts which will increase the density of the aqueous 
formulation may also be used, for example, sodium sulfate, potassium 
chloride, potassium sulfate or ammonium sulfate. The use of salts which 
will introduce cations forming insoluble products with other ingredients 
of the compositions should be avoided. For this reason, calcium and 
magnesium salts will generally not be used as densifiers because the 
calcium and magnesium thioglycolates and carboxymethyl celluloses are 
insoluble. The densifying salt is present in order to ensure that when the 
formation is poured into the clogged drain, it will sink through the 
standing water in the drain to the lowest point, where the plug is 
situated. Thus, salts which give the greatest relative increase in density 
will be preferred although it will generally be found that sodium chloride 
will be adequate for this purpose. The amount of the densifying salt 
should be selected so that upon formulation, the drain cleaner remains in 
the solution form; excessive amounts of the salt which might cause certain 
ingredients to "salt out" should therefore be eschewed and generally, the 
amount of the salt will be from 10 to 25, preferably 10 to 20, percent by 
weight of the composition, particularly for the preferred sodium chloride. 
A thickener is used to increase the viscosity of the formulation in order 
to prevent rapid dilution in the standing water in the drain. For this 
purpose, the water soluble cellulose ethers such as sodium carboxymethyl 
cellulose, sodium carboxymethyl-2-hydroxyethyl cellulose, 2-hydroxyethyl 
cellulose, methyl cellulose, and the hydroxyalkyl and hydroxyalkyl alkyl 
celluloses are preferred, especially the salts of the carboxymethyl 
celluloses. Sodium carboxymethyl cellulose is an anionic cellulose ether 
manufactured by the reaction of monochloracetic acid, as either the acid 
or the sodium salt, and alkali cellulose. It is available from commercial 
sources as the salt as well as in the free acid form and it is non-toxic 
towards human beings, being physiologically inert and neither a primary 
irritant nor a sensitizing agent. This ingredient should be used in an 
amount to provide a satisfactory formulation viscosity generally in an 
amount from 1 to 10%, preferably about 1 to 5%, by weight of the total 
composition, depending upon the thickening effect of this ingredient. 
Preferred finished formulations for the drain cleaner compositions will use 
the active ingredients in the amounts shown below (percentages by weight): 
______________________________________ 
Broad Preferred 
______________________________________ 
Solvent 5-20 5-15 
Surfactant 0.1-5 0.1-2 
Depilatory 1-10 1-5 
Densifier 10-25 10-20 
Thickener 1-10 1-5 
Water 50-80 50-80 
______________________________________ 
The preferred compositions contain N-methyl-2-pyrrolidinone as the solvent, 
a fluorosurfactant, sodium thioglycolate as the thioorganic compound, 
sodium chloride as the densifier and sodium carboxymethyl cellulose as the 
thickener. 
Accelerators for reducing the time required for the decomposition of hair 
and other protein fibers may be added, for example, the alkali metal 
silicates, thiourea, urea, melamine, dici-yan-diamide or other 
conventional materials for this purpose in their conventional quantities. 
Corrosion inhibitors may be added although since the thioglycolates also 
serve to prevent corrosion in metallic drain systems, this may not be 
required. Sequestering agents and other material such as those used to 
improve consumer sensory appeal, e.g. fragrances and dyes may also be 
present in conventional quantities. 
The drain cleaner compositions are conveniently formulated as aqueous 
solutions although, as previously mentioned, emulsions or dispersions are 
also contemplated. 
EXAMPLE 
The following formulation was prepared: 
______________________________________ 
Water 1000 g 
Carboxy Methyl Cellulose, Sodium salt 
30 g 
Table Salt (NaCl) 250 g 
N--Methyl-2-Pyrrolidinone 
150 g 
Surfactant, Zonyl.sup.R FSN 
5 g 
Sodium Thioglycolate 53 g 
______________________________________ 
Note: 
Zonyl FSN is a fluoroalkyl poly(ethylene oxide) ethanol nonionic 
surfactant manufactured by DuPont. 
Tests showed that this formulation dissolved grease plugs as fast as a 
commercially available caustic drain cleaner and that the formulation 
removed hair plugs, although not as fast as the same caustic cleaner. The 
formulation is non-toxic upon skin contact and oral toxicity (LD.sub.50, 
adults) is approximately 500 ml.