Note: Descriptions are shown in the official language in which they were submitted.
COMPOSITION OF MATTER CONTAINING
IMIDAZOLIDINYL UREA AUDI PARABENS
BACKGROUND OF THE INVENTION
It is widely recognized in the art of cosmetic
preservation that the combination of imidaæolidinyl urea
and parabens constitute a highly effective preservative
system against bacteria, yeasts and molds. Imidazolidinyl
urea is the name given to a bactericidal compound prepared
as described in Example IV of United States Patent
3,248,285 and has been given a Chemical Abstract Service
Registry No. 39236-46-~. Paraben is the generic name for
the family of esters of p-hydroxybenæoic acid which exhibit
anti-microbial activity.
Typically, the imidazolidinyl urea-paraben system
is formed from equal parts by weight of imidaæolidinyl urea
and paraben. A system containing imidazolidinyl urea,
methyl paraben and propylparaben in the weight ratio of
3:2:1 is perhaps the most common combination employed for
cosmetic preservation.
However, imidazolidinyl urea is soluble in water
whereas methyl and propel paraben are only very slightly
water soluble. Accordingly, the preparation of a presser-
votive system based upon these compounds which is compel-
isle in a variety of products requiring preservation
against contamination by microorganisms, including aqueous
s
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based products, is a problem.
As heretofore practiced, the three components of
the preservative system are incorporated into emulsion-
type products, i.e., creams and lotions, in three separate
steps. The propylparaben is first dissolved in the oil
phase of the emulsion since it is soluble in numerous oils,
but insoluble in water. On the other hand, the methyl par-
amen is typically dissolved in the aqueous phase which
requires continuous heating since the methylparaben
crystals dissolve very slowly in water. Heating the water
accelerates the dissolution slightly. Imidazolidinyl urea
is dissolved readily in the aqueous phase with only simple
stirring.
Alternatively, the methyl and propel parabens
may be redissolved in a solvent in which they are mutually
compatible, typically an organic solvent such as alcohol
or propylene glycol. The resulting solution is then incur-
prorated into the product. Imidazolidinyl urea is then
dissolved into the aqueous phase of the emulsion.
Other methods of dissolving parabens involve
dissolving them in boiling water or first preparing the
sodium salts of the parabens which are water soluble. Both
methods are costly, time consuming and cause destruction of
some of the parabens.
Attempts to incorporate a blended mixture of
imidazolidinyl urea, methylparaben and propylparaben
directly into an emulsion have failed due to the insole-
ability of imidazolidinyl urea in oil and paraben in water,
so that the blended mixture fails to dissolve completely
in either phase. Likewise, attempts to incorporate a
blended mixture of the compounds into an aqueous-based
(non-emulsion) product have been unsuccessful due to the
insolubility of parabens in water.
SUMMARY OF THE INVENTION
The present invention is based upon the discovery
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of a composition which is readily incorporated into
emulsions and aqueous-based products in amounts which are
effective to preserve the product against bacteria, yeasts
and molds. The composition is comprised of:
29 to 31%, by weight, imidazolidinyl urea,
I 9 duo 12%, by weight, methylparaben,
I 2 to 4%, by weight, propylparaben; and
55 to 57%, by weight propylene glycol.
The most preferred composition of the invention consists
of:
30~, by weight, imidazolidinyl urea,
11~, by weight, methylparaben,
3%, by weight, propylparaben; and
56%, by weight propylene glycol.
DETAILED DESCRIPTION OF THE INVENTION
The composition of the invention differs from
previous imidazolidinyl urea-paraben preservative systems
in several significant ways. It contains significantly
less parabens than conventional systems, but remains effect-
ivy against bacteria, yeasts, and molds. It is soluble in
water in amounts up to approximately 1.7%, by weight.
Generally speaking, an amount of about 1% by weight is an
effective amount for preserving against microbial con tam-
inaction. In contrast, a preservative system consisting ofimidazolidinyl urea, methylparaben and propylparaben, in
a weight ratio of 3:2:1, is not soluble in water at a
concentration of 1% by weight. Hence, the complicated
processing methods previously described are required to
incorporate this system into a product while the compost-
lion of the invention can be incorporated in one simple
step.
The composition of the invention, therefore,
provides several advantages over existing preservative
systems containing imidazolidinyl urea and parabens. In
addition to simplifying the process for incorporating
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parabens into the product, the composition of the invention
avoids destruction of paraben, reduces the time for prep-
axing a preserved product, reduces energy costs and
eliminates the need to inventory three separate preserve-
live compounds.
The composition of the invention is particularly attractive for use in cosmetic products because it can be
added at any stage in the cosmetic manufacturing process
including the cooling stage after the cosmetic has been
completely formulated. It is readily incorporated in
aqueous-based products, emulsions and solid formulations,
in a single weighing. Typical cosmetic products which are
effectively preserved by the composition of the invention
are creams, lotions, shampoos, hair conditioners, eyeliners
and other eye make-up products.
In addition to cosmetics, the composition of the
invention may be used to preserve almost any substance
which is susceptible to microbial contamination including
foodstuffs and pharmaceutical formulations. While effect-
ivy amounts vary depending upon the product being preserved generally the amount of the composition of the invention
incorporated into a product will not exceed 1.0~, by weight.
The invention, therefore, also relates to a method
of preserving products susceptible to microbial contamina-
lion by incorporating therein an effective amount of the composition of the invention, and the products so preserved.
To prepare the composition of the invention the
imidazolidinyl urea and methyl and propylparabens are
blended into propylene glycol in amounts to achieve the
final concentrations. Generally, it is preferred to add
the imidazolidinyl urea first to the propel glycol, possibly
at a slightly elevated temperature to facilitate dozily-
lion. Thereafter, the parabens are added. Heating is
typically discontinued when the parabens are added to avoid
destruction of paraben. Further details of the manner of
making and using the composition are found in the Examples
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which follow, it being understood that their purpose is
solely illustrative and in no way intended to limit the
scope of the invention.
Example
Preparation of composition -
In a 5-liter, three-necked, round-bottom flask
equipped with stirrer, condenser, thermometer, and heating
mantle was put 2240 g. of propylene glycol. The tempera-
lure of the propylene glycol was maintained at 70C by
heating while a total of 1200 g. of imidazolidinyl urea
(Germ all 115) was added. Heating was discontinued, and
440 g. of methylparaben and 120 g. of propylparaben was
added to the stirred solution. The bath temperature
dropped from 70C to 57C, and was maintained above 55C
until all the parabens had dissolved tl5-30 minutes).
The solution was filtered to give a clear colorless liquid
filtrate.
Example II
Antimicrobial activity of composition after
dilution with 99 parts of water -
(a) Activity against bacteria (Pseudomonas
aeruginosa)
A 0.5 ml Alcott (containing approximately 107
organisms per ml) of a 24-hour AWOKE. broth culture of
Pseudomonas aeruginosa (ATTICS 9027) was added to 4.5 ml of
test solution (1 part composition parts water) and mixed
well. The test solution was then stored at 35C in an
incubator for three days. A 0.1 ml Alcott was aseptically
removed from the test solution and placed into a tube
containing AWOKE. broth with Lithuania. The inoculated
subculture tube was incubated at 35C for two days and then
examined for presence of growth.
The subculture showed no growth, indicating
complete kill of Pseudomonas aeruginosa in the test soul-
lion.
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(b) Activity against yeast (Candid albicans)
The same procedure was used as in (a) above,
except that Suborned Liquid Medium with Lithuania was used
in place of AWOKE. broth with Lithuania
The subculture after two days incubation showed
no growth, indicating complete kill of Candid albicans
(ATTICS 10231) in the test solution.
(c) Activity against mold (Aspergillus Niger
- The growth of a 7-10 day slant of Aspergillus
Niger (ATTICS 16404) was washed off with 10 ml of sterile
saline solution. A 0.5 ml Alcott of this suspension was
added to 4.5 ml of the test solution (1 part composition:
99 parts water) and mixed well. The test solution was
stored at room temperature (25C) for three days. A 0.1 ml
Alcott was removed and placed into Suborned Liquid Medium
with Lithuania, and incubated for 7 days at room temperature
(25C) and then examined for presence of growth.
The subculture showed no growth, indicating
complete kill of Aspergillus Niger in the test solution.
While the invention has now been described in
terms of certain preferred embodiments, and exemplified
with respect thereto, those of skill in the art will
readily appreciate that various modifications, changes,
omissions, and substitutions may be made without departing
from the spirit of the invention. It is, therefore,
intended that the present invention be limited solely by
the scope of the following claims.
