Thickened alcoholic antimicrobial compositions

A thickened alcoholic antibacterial composition is provided which contains as a thickener a polymer having as the recurring structural unit an acrylamidoalkanesulfonic acid monomer or ammonium salt thereof. Methods of thickening an alcoholic antibacterial composition and methods of controlling bacteria with such compositions are also provided.

FIELD OF THE INVENTION 
This invention relates to alcoholic antibacterial compositions thickened 
with a synthetic polymer. More particularly, this invention relates to 
alcoholic antibacterial compositions thickened by a polymer comprised of 
an acrylamidoalkanesulfonic acid monomer or the ammonium salt thereof. 
BACKGROUND OF THE INVENTION 
U.S. Pat. No. 3,931,089 discloses a homopolymer of 
2-acrylamido-2-methylpropanesulfonic acid or its salts is stable as a 
thickener in highly acidic aqueous solutions which may also contain a 2-3 
carbon alcohol. The patent discloses that the acid homopolymer and the 
alkali and alkaline earth metal salts of the homopolymer are very soluble 
in strong acid solutions. 
U.S. Pat. No. 4,065,422 to Lundmark, et al., discloses that homopolymers of 
salts of 2-acrylamido-2-methylpropanesulfonic acid impart lubricity to 
alcohol base compositions. The patent discloses that the homopolymers of 
salts which contain as cations sodium, potassium, ammonium, 
monoethanolamine, diethanolamine, triethanolamine, and 
2amino-2-methyl-1-propanol are water soluble polymers and that 
homopolymers of the salts, calcium and magnesium, are water-insoluble. 
U.S. Pat. No. 4,065,422 states that the alcohols useful in the compositions 
of that invention are the C.sub.1 -C.sub.24 alcohols such as methanol, 
ethanol, isopropanol, propyl, lauryl, myristyl, cetyl and stearyl 
alcohols, as well as mixtures thereof. The patent goes on to state that 
the polymers of their invention are surprisingly soluble in monohydric 
alcohols in view of the molecular weight of the polymer and the lesser 
solubility of acrylamide polymers of similar molecular weight. However, 
the patent acknowledges that solubility of the polymers is not important 
in the applications comtemplated therein, so long as the polymer is 
dispersible in the alcohol. Moreover, in Example 9, the patent states that 
the sodium salt of the homopolymer is dispersed in ethanol. 
U.S. Pat. No. 4,412,026 to Collins discloses that an aldehyde containing 
composition is thickened by the use of salts of 
polyacrylamidomethylpropanesulfonic acid. 
U.S. Pat. No. 4,412,027 to Klein, et al., discloses that salts of 
polyacrylamidomethylpropanesulfonic acid thickened ketone containing 
compositions. 
SUMMARY OF THE INVENTION 
This invention relates to alcoholic antibacterial compositions containing a 
thickening amount of a polymer having the recurring structural unit: 
EQU --(CH.sub.2 --CH(C(O)NH--R--SO.sub.3 M))-- 
wherein R is a divalent hydrocarbon group and M is a hydrogen atom or an 
ammonium group. This invention also relates to methods of thickening an 
alcoholic antibacterial composition and to the use of the thickened 
alcoholic antibacterial composition as an antibacterial agent. 
DETAILED DESCRIPTION OF THE INVENTION 
The alcoholic antibacterial compositions that are thickened for the 
practice of this invention generally contain one or more alcohols having 
antibacterial activity. Examples of suitable alcohols are the alkanols 
having from 1-8 aliphatic hydrocarbon atoms and mixtures thereof. These 
alkanols can also be used in admixture with aromatic substituted alkanols 
such as beta-phenethyl alcohol and benzyl alcohol. The alcoholic 
antibacterial compositions of this invention preferably contain ethanol, 
propanol and benzyl alcohol as the active ingredients. 
The preferred alcoholic antibacterial compositions preferably contain as 
active ingredients, a major portion (e.g. between about 40% and about 50% 
by weight) ethanol (wherein the ethanol contains 4% water), a minor 
portion (e.g. between about 20% and 30% by weight) anhydrous isopropanol, 
and a nominal amount (e.g. about 0.5% to about 2% by weight) benzyl 
alcohol. 
The alcoholic antibacterial compositions of this invention may also contain 
hydrogen peroxide as a supplemental antibacterial agent. A preferred 
example of an alcoholic antibacterial composition which contains hydrogen 
peroxide as an antibacterial agent is SPITADERM.RTM. from Henkel KGaA 
which is composed of 70% isopropanol, 0.5% chlorohexidinedigluconate, 
0.45% hydrogen peroxide and balance water. Alternatively, the hydrogen 
peroxide may be present in only trace amounts, i.e. as the residue of 
hydrogen peroxide disinfectant used in sterilizing the equipment and the 
containers which are used for processing and transporting the alcoholic 
antibacterial compositions. The amount of hydrogen peroxide in the 
alcoholic antibacterial composition may therefore range from trace amounts 
up through about 2% by weight of the composition. Because hydrogen 
peroxide generates free radicals in solution which cause the degradation 
of the polymeric thickener over time, the preferred antibacterial 
compositions contain little or no hydrogen peroxide. 
It has also been found that brucine sulfate, a common denaturant for 
ethanol, will complex with the polymeric thickener over time. The 
formation of this complex, like the degradation of the polymer by hydrogen 
peroxide generated free radicals, leads to a slow gradual loss of 
viscosity over a long period of time. To achieve optimum shelf life, 
ethanol having a denaturant other than brucine sulfate should be used in 
the alcoholic compositions of this invention. 
The polymeric thickener useful in the present invention is a polymer 
wherein the major recurring structural unit is derived from an 
acrylamidoalkanesulfonic acid or an ammonium salt thereof. These polymers 
are generally described in U.S. Pat. No. 3,692,673 which is incorporated 
herein by reference thereto. The preferred polymer is obtained by 
polymerizing amount of a mixture that is at least about 50% by weight of 
2-acrylamido-2-methylpropanesulfonic acid or an ammonium salt thereof. The 
most preferred polymers are homopolymers of 
2-acrylamido-2-methylpropanesulfonic acid or an ammonium salt thereof. 
The polymer is preferably prepared by means which will provide a polymer 
having a molecular weight between about 50,000 and about 5,000,000. The 
molecular weight of the polymer is more preferably greater than about 
500,000 and is most preferably greater than about 1,000,000. 
To determine the molecular weight of the preferred polymers of this 
invention, i.e. homopolymers of 2-acrylamido-2-methylpropanesulfonic acid 
or a salt thereof, the intrinsic viscosity of the polymer can be used in 
the Mark-Houwink equation: 
EQU [n]=KM.sup.a 
wherein [n] is the intrinsic viscosity, M is the molecular weight and K and 
a are constants for the particular polymer solvent combination. Values of 
K and a are extensively tabulated in the Polymer Handbook, Brandum and 
Immergent (1975). Because the values of K and a are not tabulated for 
poly(2-acrylamido-2-methylpropanesulfonic acid), the values for 
poly(acrylic acid) are used in the Mark-Houwink equation to determine the 
molecular weight of the preferred homopolymers useful in this invention. 
The preferred means of preparing the polymers useful in this invention is 
by aqueous redox polymerization which may be affected by standard redox 
polymerization techniques using standard redox catalysts. Examples of 
suitable redox catalysts include ammonium bisulfite, ferrous sulfate, 
hydrogen peroxide, and sodium metabisulfite. It is desirable to exclude 
oxygen from the reaction vessel as it may inhibit the polymerization 
process. The temperature of the reaction mixture is not critical but 
should be maintained between about 2.degree. C. and 60.degree. C. The 
molecular weight of the homopolymer so obtained will range from about 
50,000 to about 5,000,000 as determined by its intrinsic viscosity. Chain 
transfer agents such as mercaptosuccinic acid may be employed in the 
polymerization reaction to obtain homopolymers of the desired molecular 
weight. 
The amount of polymeric thickener added to the alcoholic antibacterial 
composition will vary depending upon the amount of thickening desired in 
the antibacterial composition and the particular molecular weight of the 
chosen polymeric thickener. In general, the polymeric thickener is added 
in an amount from about 0.2% to about 2% dry weight of polymeric thickener 
as a percentage of the weight of the alcoholic antibacterial composition, 
more preferably from about 0.5% to about 1%. 
The polymeric thickener can be added to the alcoholic antibacterial 
composition in the form of the solution resulting from the solution 
polymerization of the acrylamido alkanesulfonic acid monomer and/or 
ammonium salt thereof. The polymeric thickener can also be added as the 
dried product obtained by drying the solution polymerization product. It 
has been found that the dry form of both the acid and the ammonium salt of 
the homopolymers of 2-acrylamido-2-methylpropanesulfonic acid hydrate 
fully within 15 minutes of their addition to an alcoholic antibacterial 
composition. 
The thickened antibacterial compositions of this invention are useful in 
controlling the growth of a wide variety of bacteria. These compositions 
can be used both as antiseptics and as disinfectants. It has been found 
that the polymeric thickeners useful in this invention provide excellent 
thickening and body to alcoholic antibacterial compositions. It has also 
been found that the thickened antibacterial compositions when used as 
antiseptics impart a very desirable hand feel, even after a water or 
alcohol rinse.

EXAMPLES 
The following examples illustrate the preparation and properties of 
alcoholic antibacterial compositions thickened in accordance with this 
invention. 
DEFINITIONS 
Alcoholic Antibacterial Composition (AAC): A mixture comprised of 
approximately 46% by weight ethanol (which contains about 4% water and has 
been denatured), 27% anhydrous isopropanol, 1% benzyl alcohol and balance 
water, which is available from Henkel KGaA as Spitacid.RTM.. 
Polymeric Thickener #1: dried flakes of 
poly(2-acrylamido-2-methylpropanesulfonic acid) available from the Henkel 
Corporation as Rheothik 80-11. 
Polymeric Thickener #2: dried flakes of poly(ammonium 
2-acrylamido-2-methylpropanesulfonate) obtained as disclosed in U.S. Ser. 
No. 636,647 filed July 31, 1984, now abandoned. 
Polymeric Thickener #3: a 15% solids solution of Rheothik.TM. 80-11 
available from the Henkel Corporation. 
Comparative Thickener: the dried polymer 
poly(sodium-2-acrylamido-2-methylpropanesulfonate) obtained by 
polymerizing sodium-2-acrylamido-2-methylpropane sulfonate by techniques 
such as those disclosed in U.S. Pat. No. 4,065,422. 
EXAMPLE 1 
A 2 g sample of Polymeric Thickener #1 were added to 98 g of the AAC, and 
the resulting solution was stirred on a magnetic stirrer. The polymer 
dissolved within 10 minutes to yield a very thick solution. 
EXAMPLE 2 
A 1 g sample of Polymeric Thickener #1 was added to 99 g of the AAC, and 
was stirred as in Example 1. Within 10 minutes the polymer was completely 
dissolved to yield a solution that was thinner than the solution of 
Example 1, but was still very thick. 
EXAMPLE 3 
A 1/2 g sample of Polymeric Thickener #1 was added to 99.5 g of the AAC, 
and was stirred as in Examples 1 and 2. Within 10 minutes the polymeric 
thickener was completely dissolved to yield a solution with a viscosity 
desirable in a pourable antiseptic, i.e. a Brookfield viscosity between 
about 300 and about 400 cps. 
EXAMPLE 4 
A 1/2 g sample of Polymeric Thickener #2 was added to 99.5 g of the AAC, 
and was stirred as in Examples 1-3. Within 5 minutes the Polymeric 
Thickener was completely dissolved to yield a solution with a viscosity 
similar to that of Example 3. 
EXAMPLE 5 
A 3.33 g sample of Polymeric Thickener #3 was added to 96,66 g of the AAC 
(0.5% Polymeric Thickener on a dry basis) and stirred as in Examples 1-4. 
The liquid dispersed within one minute to yield a solution having a 
viscosity similar to that of Examples 3 and 4. 
COMATIVE EXAMPLE A 
A 1/2 g sample of Polymeric Thickener A was added to 99.5 g of the AAC, and 
the resulting mixture was stirred on a magnetic stirrer. The Polymeric 
Thickener did not appear to be soluble in the AAC and did not apreciably 
thicken the AAC even after two days of continuous mixing.