Note: Descriptions are shown in the official language in which they were submitted.
"~' llZ-~70Z
ANTIMICROBIAL COMPOSITIONS AND METHOD OF USE
BACKGROUND OF THE INVENTION
Antimicrobial compositions are gener-
ally added to various kinds of aqueous fluid
media to reduce or inhibit the growth of micro-
organisms.
For instance, a wide variety of indus-
trial aqueous fluid media are known such as metal
working fluids used with metal working equipment.
The development of high speed metal
cutting and grinding has resulted in the crea-
tion of lubricants containing oils and chemicals
stabilized in water. These fluids impart the
cooling qualities of water and the lubricating
properties of oil which prolongs the life of
cutting tools, reduces heat production, improves
surface finish of the metal being machined, pre-
vents warping and leaves a rust-inhibiting film
of oil on the worked piece.
Normally these fluids consist of fatty
or petroleum oils, soaps or synthetic based
materials and additional additives such as anti-
foam agents, EP additives, preservatives, coupl-
~ ing agents and rust inhibitors. The coolants are
" 25 generally marketed in the form of concentrates
which are normally diluted with water by the user
in ratios of 1 part oil to about 20-40 parts of
water, but these ratios may vary with particular
operations. The lubricant is supplied to a
~: 30 machine from either an individual tank containing
fifty to one hundred gallons cr from a large sump
containing thousands of gallons which supplies
many machines.
',
.'' ~
lt;~
One of the problems often associated
with such aqueous fluid media arises from the
susceptibility of the media to the infestation
and growth of various microorganisms such as
bacteria and fungi (which particularly feed on
the organic components thereof). The presence
and buildup of such microorganisms can often
lead to interference in the metal working opera-
tions as a result of the clogging of filters,
buildup of slime and sludge, development of
odors, rust, emulsion instability, reduced toollife and poor finish. Furthermore, in machine
shops where the workers' hands necessarily come
in contact with the cutting oil, usually con-
taining finely divided sharp metal cuttings,serious problems of dermatitis may arise.
These and other such similar problems have
resulted in the continuing need for better
antimicrobial additives for aqueous fluid
media such as metal working fluids. ~uch
effort has been devoted in recent years to
controlling this problem; however, it continues
to be a major annoyance wnich costs the metal
working industry many millions of dollars each
year.
A number of suggestions have been
made for inhibiting the growth of bacteria in
¦ aqueous fluids such as those described in U.S.
Patents No. 4,012,261; 3,591,679; 3,408,843 and
30 3,240,701. The use of various formaldehyde preser-
vatives for metal working fluids including mono-
methylol dimethyl hydantoin and dimethylol dimethyl
~,
~ 37(~;~
hydantoin has also been proposed (See Bennett, E.O.,
Int. Biodetn. Bull. 9, pages 95-100, 1973 and Maeda
et al., Agr. Biol. Chem., 40, 1111-2222, 1976).
Gray and Wilkinson in J. Gen. Microbiol.,
39, 385-399 (1965) and J. App. Bact., 28, 153-164
(1965) describe the action of ethylenediaminetetra-
acetic acid (hereinafter sometimes referred to as
"EDTA") on some bacteria. The effectiveness of such
chelating agents as EDTA alone for bacterial control
in aqueous systems is disputed as evidenced by U.S.
Patents No. 3,240,701; 3,408,843 and 3,591,679.
The antimicrobial compositions used in metal work-
ing fluids seem to suffer from one or more disadvan-
tages including high-cost, unacceptable toxicity or
low degree of effectiveness at the present state
of the art.
Accordingly, it is the primary object
of the present invention to provide an effective
antimicrobial composition formulation for use in
an aqueous fluid medium.
A further object of the present inven-
tion is to provide an effective relatively non-
toxic method for inhibi~ing the growth of micro-
organisms in an aqueous fluid medium susceptible
to such growth.
These and other objects of our inven-
tion will be apparent from the discussion which
follows.
3.1 Z37U2
SUMMARY OF THE INVENTION
We have discovered antimicrobial com-
positions, suitable for inhibiting the growth
of microorganisms in an aqueous fluid medium
susceptible to such growth, comprising as an
active ingredient a condensation product of
5,5-dimethyl hydantoin and formaldehyde (e.g.,
the mono- or dimethylol dimethyl hydantoin) in
combination with a water-soluble chelating agent.
A preferred antimicrobial composition formula-
tion comprises as an active ingredient 1,3-
dimethylol-5,5-dimethylhydantoin (hereinafter
sometimes referred to as "DMDMH") in combina-
tion with ethylenediaminetetraacetic acid or a
water-soluble salt thereof, e.g., with alkali
metal or ammonium salts.
These antimicrobial compositions when
added to an aqueous fluid medium provide an un-
expected degree of preservation and antimicrobial
activity over what one would expect from results
obtained by using the hydantoin-formaldehyde
condensation product or chelating agent (i.e.,
DMDMH, EDTA, or a salt thereof) alone.
DETAILED DESCRIPTION OF THE INVENTION
The antimicrobial compositions of our
invention thus comprise an active combination
of a condensation product of 5,5-dimethyl
¦ hydantoin and formaldehyde (e.g., 1,3-dimethylol-
1 5,5-dimethyl hydantoin, 1-methylol-5,5-dimethyl
112370~
-- 5
hydantoin, or 3-methylol-5,5-dimethyl hydantoin, 1,3-
dimethyloloxy-methylene-5,5-dimethylhydantoin and
mixtures thereof) and a water-soluble chelating agent.
Condensation products of 5,5-dimethyl-
hydantoin (hereinafter referred to as "DMH") and for-
maldehyde are well known. Eor example, DMDMH may be
prepared as described in U.S. Patent No. 3,987,184.
This patent describes the use of e.g., 40-75% aqueous
solutions of DMDMH as a formaldehyde donor, as well as
a preservative, in various pastes, soaps, skin creams,
liquid shampoos and other similar preparations.
The condensation products of DMH and formalde-
hyde as used herein are intended to include those
products wherein 1,2 or more moles of formaldehyde are
condensed with each mole of DMH. Thus, the condensation
products include those wherein more than 2 moles of
formaldehyde may be condensed with each mole of DMH,
such as, for example l-methylol-3-methyloloxymethylene-
5,5-dimethyl hydantoin and 1,3-dimethylol-oxymethylene-
5,5-dimethyl hydantoin.
When added to an aqueous fluid medium, we
have now found that when an antimicrobial DMH-formalde-
hyde condensation product such as DMDMH is used in
combination with a chelating agent such as EDTA or a
water-soluble EDTA salt a greatly enhanced degree of
antimicrobial activity is obtained. When a chelating
agent such as EDTA (or an EDTA water-soluble salt)
,.",
llZ~7(,';~
i 6
'I
¦ is used alone (at the concentration levels here
involved), there is generally no significant
antimicrobial activity exhibited. Further, while
antimicrobial activity is observed when the
DMH-formaldehyde condensation product alone is
used by itself, the level of such activity is less
than is desired. However, when according to the
invention the chelating agent is used in combina-
tion with the DMH-formaldehyde condensation pro-
duct, for reasons not entirely clear at present,the presence of the chelating agent has an unex-
pected effect of potentiating or greatly enhancing
the antimicrobial activity of the said hydantoin-
condensa.ion component, as is more fuily described
below.
As used herein, chelating agents aredefined as water-soluble substances which when
added to an aqueous fluid medium, reduce the
normal ionic effects of the cations present.
~ Suitable chelating agents according to the pre-
sent invention may include EDTA, and diethylene-
triamine pentaacetic acid (hereinafter sometimes
DTPA) and similar compounds as well as their
i water-soluble salts (e.g., sodium salts).
While ethylenediaminetetraacetric
acid itself may be employed, it is preferred
to use one of its water-soluble salts, such as
alkali metal salts, for example the disodium salt
(sometimes referred to as "EDTA diNa") or the
tetra-sodium salt (sometimes referred to herein-
after as "EDTA-tNa"). The comparable potassium
salts, and the ammonium salts may also be used.
~LlZ~'17(~'~
The antimicrobial compositions of the
present invention may thus generally be formu-
lated to contain the active hydantoin-formalde-
hyde condensation product and chelating agent in
a weight ratio ranging from about 0.25:1 to 20:1,
and preferably about 1:1 to S:l hydantoin to
chelating agent with or without additional
inert liquid vehicles or dispersants, or solid
extenders, or inert carriers. Most preferably,
and conveniently, compositions may be formulated
containing less than about 5% by weight of the
chelating agent.
In use these antimicrobial composition
formulations may be added to an aqueous fluid
lS medium in the form of a solid block or tablet,
as a powder, or preferably as a solution.
In order to achieve practical level
of inhibition of microorganism growth in the
aqueous fluid medium it is necessary to include
therein the combination of active hydantoin
(i.e., mono- or dimethylol-5,5-dimethyl hydan-
toin) and chelating agent in an amount sufficient
to inhibit the growth of microorganisms. As used
herein, the term inhibitive amount is to be
understood as that amount of the said combination
which when added to an aqueous fluid medium will
acceptably inhibit the growth of microorganisms
in the use of said medium. Furthermore, this
level of inhibition will be greater than the
additive level of inhibition one would obtain
with the active hydantoin product in the absence
of the chelating agent (e.g., 1 part DMDMH and 1
¦ part EDTA is more inhibitory than 2 parts DMDMH
alone).
7~
Generally at least 500 parts of the
chelating agent and at least 500 parts of active
hydantoin are added per million parts of the
aqueous fluid medium. Thus, the chelating agent
S may be added in amounts ranging from about 500 to
4000 parts per million (ppm) of the aqueous fluid
medium. Likewise, one may suitably add from
about 500 to 10000 parts of active hydantoin
per million parts of the aqueous fluid medium.
The weight ratio of condensation product and
chelating agent may range suitably from about
0.25:1 to 20:1 and preferably about 1:1 to 5:1.
Of course, with an increase in water hardness,
the proportional amount of chelating agent may
lS need to be increased to achieve desired results.
As used herein, the term aqueous
fluid medium is meant to encompass water, oil
in water, water in oil emulsions (including
concentrates) and like compositions susceptible
to the infestation and growth of microorganisms.
Thus, for instance, metal working fluids or
cutting oil fluids (in diluted as well as un-
diluted form) together with conventional addi-
tives such as corrosion inhibitors etc. are to
be included.
The antimicrobial compositions maybe added directly to undiluted metal working
fluids. As used herein the term "metal working
fluid" is intended to encompass those composi-
tions known in the art as "metal cutting fluids","cutting fluids", "coolants", "lubricants"
"rolling oils", "drawing fluids", "mold release
fluids", "grinding fluids" and like products used
in the processing of metals as described more
i
!
7(~;~
fully by Springborn, R.K. "Cutting and Grinding
Fluids: Selection and Application," ASTME (1967 )
and Wilbert J. Olds, "Lubricants, Cutting Fluids
and Coolants", Cahner's Books, the entire contents
of each being incorporated herein by reference.
Emulsifiable or water miscible oils are widely
used in the industry. Mixed with water, they
form emulsions for use in rolling, drawing,
machining and grinding where the need is for both
cooling and lubrication. More recently, water
miscible fluids using less oil (or no oils) and
based on chemicals with or without surface active
agents, have provided industry with products of
even greater heat conducting properties for still
higher machining rates.
The following examples are offered
in order to more fully illustrate the invention,
but are not to be construed as limiting the scope
thereof.
EXPERIMENTAL PROCEDURE
.
Test units employed consisted of quart
jars placed in rows. Above each row a metal
framework was constructed to support the aera-
tion system which consisted of aquarium valvesconnected together with plastic tubing. The
amount of aeration of each jar unit was con-
trolled by adjusting the valves. Capillary
pipettes were employed as aerators to produce a
fine stream of bubbles.
Five hundred ml of tap water (moderate
hardness) was added to each jar unit. DMDMH and
EDTA and DTPA were used as obtained from the
manufacturer and the desired amount (wt/vol or
7(~;~
vol/vol) of each product was added to each unit
along with the required amount of coolant con-
centrate to produce the desired oil-water ratio.
(DMDMH was used as a 55% aqueous solution,
identified as "DMD~H-55"). The unit was then
made up to a total volume of 600 ml with addi-
tional tap water.
The jars were inoculated with a mix-
ture of bacteria and fungi which were obtained
and maintained as described in "The Deterioration
of Metal Cutting Fluids," Prog. Indust. Microbiol.,
13, 121-249, 1974 by E.O. Bennett, the entire
contents of which are incorporated herein by
reference. Over the years, samples of spoiled
coolants have been obtained from many sources.
These samples have been kept viable by growing
them in metal working fluids. The inoculum
employed in the antimicrobial tests contains
these organisms and is aerated at all times.
Normally, it contains between ten million to
one hundred million organisms per ml.
Initially and once each week there-
after all units were inoculated with 1.0 ml
of a 50-50 mixture of the two inocula (i.e.,
bacteria and fungi). The units were kept at
ambient temperatures (27.0C. to 28.5C.).
The test units were studied for their
microbial content at weekly intervals by making
serial dilutions of the coolar.t into a medium as
described in the Prog. Indust. Microbiol. article
noted above. Each unit was studied for so long
as the counts remained below 100,000 organisms/ml.
I
112.~70;~
11
Two consecutive counts in excess of this figure
at weekly intervals was considered to constitute
the point of "failure", and the test was discon-
tinued at that time.
Since the test vessels were under con-
stant aeratlon, there was considerable evapora-
tion from each jar unit. The units were calib-
rated at the 600 ml mark and once or twice each
week distilled water was added to bring the
liquid level back to this mark. Distilled water
was used in order to avoid a buildup of inorganic
salts which would have taken place if tap water
had been employed.
Base control tests in each instance
revealed that the coolants employed without the
addition of chelating agent and/or hydantoin
product failed within one week due to the growth
of microorganisms.
Examples A and B are comparative
examples; Examples 1 through 4 are illustrative
embodiments of this invention.
EXAMPLE A
A series of sample jar units were
prepared according to the procedure outlined
above in order to ascertain the antimicrobial
effect of 1,3-dimethylol-5,5-dimethyl hydantion.
Samples tested were
A) 1500 ppm of 55% aqueous
solution of 1,3-dimethylol-5,5-
dimethylhydantoin (hereinafter
sometimes referred to as "DMDMH-55");
B) 3000 ppm DMDMH-55; and
C) 4500 ppm DMDMH-55.
1~2;~'7(};~
The samples were tested with the
following commercially available coolants (i.e.
metal working fluids):
Coolant Manufacturer
...
5 Max Mix Coolant Mack Co.
Shell Emulsion Shell Oil Co.
Vantrol Emulsion Van Straaten Chemical Co.
Sun Emulsion Sun Oil Corp.
Monroe Emulsion Monroe Chemical Corp.
10 Norton Emulsion Norton Co.
Shamrock Emulsion F.E. Anderson Oil &
Chemical Corp.
DoAll Coolant Do All Co.
Quaker Coolant Quaker Chemical Corp.
Texaco Émulsion Texaco Inc.
15 Irmco Emulsion International Refining &
Manufacturing Corp.
Polar Chip Coolant Polar Chip Inc.
Shercool Coolant Sherwin Williams Chemicals Inc.
Sanson Emulsion Sanson & Sons, Inc.
Lusol Coolant F.E. Anderson Oil & Chemical Corp.
20 Trim Coolant Master Chemical Corp.
Cimcool 5 Star Cincinnati Milacron Corp
Coolant
Union Emulsion Union Oil Corp.
The coolants were mixed with water in
a ratio of 1 to 40 (coolant to water). The
results are set forth in Table 1 below, wherein
the time in days is recorded when the count in
such test reached the level of 100,000, as
described above.
1~12~0;~
Test failures in less than 60 days
or less were considered likely to be unacceptable
from the standpoint of potential industrial and
commercial applications. Furthermore, from both
a technical and statistical standpoint any data
between about 0 to 21 days can not be regarded as
significantly different.
li;~7(~
TABLE 1
. Column A Column B Column C
~MDMH 55 ~MDMH-55 DMDMH-55
Coolant 1500 ppm 3000 ppm 4500 ppm
1. Max Mix Coolant 56 105*
2. Shell Emulsion 0 0 0
3. Vantrol Emulsion 14 7 0
4. Sun Emulsion 0 0 7
5. Monroe Emulsion 0 21 14
6. Norton Emulsion 7 2B 28
7. Shamrock Emulsion 28 105* 105*
8. DoAll Coolant 14 7 42
9. Quaker Coolant 21 21 21
15 10. Texaco Emulsion 0 14 14
11. Irmco Emulsion 0 0 0
12. Polar Chip Coolant 14 35 7
13. Shercool Coolant 0 21 7
14. Sanson Emulsion 0 0 0
20 15. Lusol Coolant 35
16. Trim Coolant 14
17. Cimcool 5 Star Coolant 7 35
18. Union Emulsion 0
25 All testing at 1 to 40 oil to water ratio.
* Still inhibitory when taken off test.
Underlined number indicates failure due t~ moulds.
llZ.~7(~;~
EXAMPLE B
A series of sample jar units were
prepared according to the procedure outlined
above in order to ascertain the antimicrobial
effect of EDTA-diNa and diethylenetriamine
pentaacetic acid (pentasodium salt). Samples
tested were
A) 1000 ppm EDTA - diNa;
B) 1500 ppm EDTA - diNa; and
C) 1000 ppm DTPA- Na5
The samples were tested with the
same commercially available coolants (i.e., metal
working fluids) used in Example 1.
The coolants were mixed with water
in a ratio of 1 to 40 (coolant to water). The
results are set forth in Table 2 below, wherein
the time in days is recorded when the count in
such test reached the level of 100,000, as
described above.
~i2.~70;~
.
16
TABLE 2
Column A Column B Column C
EDTA EDTA ~TPA
Coolant (1000 ppm)(1500 ppm)(1000 ppm)
1. Max Mix Coolant 0 - -
2. Shell Emulsion 7 - 105*
3. Vantrol EmNlsion 0 0 0
4. Sun Emulsion 0 0 0
5. Monroe Emulsion 35 35 105*
6. Norton Emulsion 14 14 21
7. Shamrock Emulsion 7 7 0
8. DQAll Coolant 0 0 35
9. Quaker Coolant 7 0
15 10. Texaco Emulsion 7 - -
11~ Irmco Emulsion 0
12. Polar Chip Coolant 0 0
13. Shercool Coolant 7 7
14. Sanson Emulsion - 7
20 15. Lusol Coolant - Q
16. Trim Coolant - 0
17. Cimcool S Star Coolant - 7
18. Union Emulsion - 0
All testing at 1 to 40 oil to water ratio.
* Still inhibitory when taken off test.
Underlined number indicates failure due to moulds.
70;2
XAMPLE 1
A series of sample jar units were
prepared according to the procedure outlined
above in order to ascertain the antimicrobial
effect of EDTA - diNa and 1,3-dimethylol-5,5-
dimethyl hydantoin. Samples tested were
A) 1500 ppm of EDTA - diNa;
B) 1500 ppm of 55% aqueous
solution of 1,3-dimethylol-5,5-
dimethylhydantoin (hereinafter
sometimes referred to as "DMDMH-55"); and
C) 1500 ppm EDTA - diNa and 1500 ppm
DMD~H-55.
The samples were tested with commer-
- 15 cially available coolants (i.e., metal workin~
fluids).
The coolants were mixed with water
in a ratio of 1 to 40 (coolant to water). The
results are set forth in Table 3 below, wherein
the time in days is recorded when the count in
such test reached the level of 100,000, as
described above.
llZ;~
18
TABLE 3
Column A Column B Column C
1500 pp~
DMDMH-55
EDrA DMDMH-55 1500 ppm
(1500 ppm) 1500 ppm EDTA
.
1. Vantrol Emulsion 0 14 84
2. Sun Emulsion 0 0 105*
3. ~onroe Emulsion 35 0 35
4. Norton Emulsion 14 7 105*
5. Shamrock Emulsion 7 28 105*
6. DoAll Coolant 0 14 105*
7. Quaker Coolant 0 21 105*
8. Polar Chip Coolant 0 14 105*
9. Shercool Coolant 7 0 105*
10. Sanson Emulsion 7 0 105*
11. Lusol Coolant 0 0 105*
12. Trim Coolant 0 14 105*
: 20 13. Cimcool 5 Star Coolant 7 7 105*
14. Union Emulsion 0 0 49
All testing at 1 to 40 oil to water ratio.
* Still inhibitory when taken off test.
Underllned number indicates f:ilu~e due to moulds.
,,
i
~12;~70Z
EXAMPLE 2
A series of sample jar units were
prepared according to the procedure outlined
above in oeder to ascertain the antimicrobial
effect of EDTA - diNa or tetra Na and 1,3-
dimethylol-5,5-dimethyl hydantoin. Samples
tested were
A) 500 ppm EDTA - diNa and 2500
ppm DMDMH-55; and
B) 500 ppm EDTA - tetra Na and
2500 ppm DMDMH-55.
The samples were tested with the
following commercially available coolants
(i.e., metal working fluids):
Coolant
Monroe Emulsion
Norton Emulsion
DoAll Coolant
Quaker Coolant
Polar Chip Coolant
Shercool Coolant
The coolants were mixed with water
in a ratio of 1 to 40 (coolant to water) as
above. In each instance, after a period of
105 days the units were still inhibited from
the growth of bacteria and fungi.
11;~.~7(~
EXAMPLE 3
A series of sample jar units were
' prepared in the same manner as Examples 1-4 in
order to determine the antimicrobial effect of
diethylenetriamine pentaacetic acid (pentasodium
salt) and DMDMH-55. Samples tested contained
2500 ppm DMDMH-55 and 500 ppm DTPA Na5.
The samples were tested with the
following coolants:
DoAll;
Shercool;
Polar Chip;
Quaker ;
Norton Emulsion; and
Monroe Emulsion.
The coolants were mixed with water
in a ratio of 1 to 40 (coolant to water). The
results are set forth in Table 4 below, wherein
the time in days is recorded when the count in
such test reached the level of 100,000, as
described above.
7(~;~
. 21
TABLE 4
2500 DMDMH-55
. Coolant 500 DTPA Na5
,~. DoAll Coolant 105*
:~
. Shercool Coolant 84
Polar Chip Coolant 105*
. Quaker Coolant 105*
Norton Emulsion 105*
, .
~. Monroe Em~lsion 105*
,-
* Still inhibitory when taken off test~
,,
.
,.
~i2~7(1'~
EXAMPLE 4
A series o~ sample jar units were
prepared according to the procedure above in
order to ascertain the antimicrobial effect of
500 ppm EDTA-diNa and 1500 ppm D~DMH-55. The
samples were tested in the same manner with the
same coolants used in Example 3. The results are
set forth in Table 5 below.
TABLE 5
1500 DMDMH-55
Coolant500 EDTA Na2
DoAll Coolant 63
Shercool Coolant 105*
Polar Chip Coolant 105*
Quaker Coolant 105*
1 20
Norton Emulsion 35
Monroe Emulsion 105*
Notes: 1. Numbers designate days inhibition.
2. Underlined numbers indicates test
failure due to mold.
3. * Still inhibitory when taken off test.
(
1~ 7l~;~
23
It will be noted that when EDTA is
used in combination with DMDMH, the test results
show that generally the resulting antimicrobial
control was maintained for multifold periods of
time longer than was observed for the same amount
of either EDTA or DMDMH used alone (at equivalent
concentrations~.
The antimicrobial composition formula-
tions of the present invention are particularly
attractive due to the low toxicity of their com-
ponents when present in the amounts indicated.
Furthermore, while prior known antimicrobial
formulations appear to be effective at best in
only about 42% of the commercially available
metal working fluids, the formulations of the
present invention are more universally effective.
While the invention has been explained
in relation to certain illustrative embodiments
of it, it is understood that many modifications
and substitutions may be made in any of the
specific embodiments within the scope of the
appended claims which are intended also to
cover equivalents of them. Furthermore, the
invention may comprise, consist or consist
essentially of the herein recited steps and
materials.
