Note: Descriptions are shown in the official language in which they were submitted.
~ 218~889
-- 1 --
T'M~IT CIFIT'~ SYSTEM WITH R~qT~T~NCE TO Bp~T~T~rl G~OWTH
Backqrolln~l of the Inventisn
Emulsifiers, which are 8t~mPt; A also called
surfactants, are widely used in numerous applications.
For instance, emulsifiers are used in making all types
of synthetic polymer latices. However, bacterial
growth in emulsif iers is an age old problem.
~atex is utilized in a wide variety of
applications. For instance, it is used in making
water-based paints, which are also known as latex
paints (see United States Patent 4,968,741), in
manufacturing carpet backing, in asphalt modification
(see United States Patent 5,002,987), in T~nllf?l~ turing
latOE rubber products, such as rubber gloves, and in a
wide variety of other applications.
After being manufactured, the latex is usually
held in inventory, shipped and stored before being
used. During this period of time, certain types of
bacteria can grow in the latex. Such bacterial growth
can destroy the properties of the latex and can cause
undesirable odors . In some cases, b~ ctPr; ~ l growth
can completely destroy the latex rendering it
unsuitable for use in manufacturing latex products.
In other cases, bacteria can later grow in latex
products, such as latex paint, destroying the
desirable characteristics of the product and causing
undesirable characteristics, such as discoloration and
odors . In any case, it is highly 1Int9P~; r~hl e for
bacteria to be allowed to freely grow in latex and
latex products.
Bactericides are of ten added to emulsif iers and
latex to limit the growth of bacteria. United States
Patent 4,442,095, United States Patent 4,442,096,
United States Patent 4,442,097, United States Patent
~ 2 1 8~889
-- 2
4, 481, 202, United States Patent 4, 507, 299, United
States Patent 4,512,991 and United States Patent
4,517,186 disclose the use of chemical bactericides to
control the growth of bacteria in latex. For
instance, United States Patent 4,481,202 discloses a
method of inhibiting the growth of bacteria and fungi
in latex paints and latex: lR;~lnq and adhesives
which comprises incorporating into the latex paints,
emulsions and adhesives 80 as to contact said bacteria
and fungi, at least a bactericidally and fungicidally
ef f ective amount of certain chemical bactericides,
such as n-octyl (2-amino-5-chloro-6- (n-
octylthio)pyrazinyl) formate, n-octyl (2-amino-5-
cloro-6- (n-methylthio)pyrazinyl) formate, and n-octyl
(2 -amino - 5 - chloro- 6- ( (l-methylethyl ) thio) pyrazinyl )
f ormate .
Chemical bactericides which can be used to
control the growth of bacteria in ~mlll R; f; ~rs and
latex are generally expensive. Even when added to
latex in relatively small amounts, the use of such
chemical bactericides can increase the cost of
manufacturing latex significantly and, in some cases,
do not provide the treated latex with a satisfactory
degree of protection against bacterial growth. Also,
in some cases, chemical bactericides cause
discoloration of the treated latex. The use of many
chemical bactericides is undesirable because they
generate f ~rr~ 1 flPhyde . The addition of chemical
bactericides to an emulsifier can also interfere with
polymerizations which are subsequently ~ ~nflll~ t~-d in
the presence of the ~mlllR;f;f~r.
United States Patent 5,478,467 discloses a water
purification device for attachment to a hose or other
water supply such that water f lowing through the
device comes in intimate contact with a treatment
media including free available silver ions to provide
21 80889
-- 3
a germicide and antibacterial treatment of the water
flowing therethrough. United States Patent 5,470,585
discloses the use of silver ions for bacteria control
on medicinal substances, such as pads, towels and
tampons. United States Patent 5,464,559 discloses a
composition for treating water with resin-bound ionic
silver.
SummarY of the Invention
This invention is based upon the discovery that
ions of metals from Group Ib of the Periodic Chart,
such as copper, silver and gold, can inhibit the
growth of bacteria in emulsifiers and latex. By
adding ions of Group Ib metals to emulsifiers or
latex, the growth of bacteria therein is greatly
inhibited. In other words, Group Ib metal ions can be
added to emulsif iers or latex as a bacterial control
agent .
The sub; ect invention more specif ically discloses
an emulsifier system which consists essentially of (1)
an emulsifier and (2) ions of a metal from Group Ib of
the Periodic Chart.
The present invention further discloses a method
for producing a latex having resistance to bacterial
growth which comprises polymerizing at least one
monomer in an aqueous emulsion which is prepared
utilizing an emulsif ier system which is comprised of
(1) an emulsifier and (2) ions of a metal from Group
Ib of the Periodic Chart.
Group Ib metal ions act synergistically with
conventional chemical bactericides to kill and inhibit
the growth of bacteria in latex. By 1lt;l;7;ng a
combination of standard organic chemical bactericides
and Group Ib metal ions, the level of chemical
bactericides and metal ions needed to satisfactorily
control bacteria growth can be signif icantly reduced.
~ 4 21 80889
Such a combination of chemical bactericides and Group
Ib metal ions accordingly offers ~ nt cost
advantages and provides treated latex with a high
degree of protection against bacterial growth.
The present invention further reveals a method
f or producing a latex having resistance to bacterial
growth which comprises (1) polymerizing at least one
monomer in an aqueous emulsion which is prepared
l~t; 1; ~;ng an emulsifier system which is comprised of
(a) an emulsifier and (b) ions of a metal from Group
Ib of the Periodic Chart; and (2) adding at least one
organic chemical bactericide to the aqueous emulsion.
Pet~; ~ed Descri~tio~ of the Invention
The technique of this invention can be employed
to provide virtually any type of emulsifier or latex
with a high degree of protection against bacterial
growth at a relatively low cost. This invention is
practiced by simply adding ions of a metal from Group
Ib of the Periodlc Chart to the emulsifier or latex
The emulsifier systems which are provided with
bacterial protection by this technique accordingly
consist essentially of (1) the emulsifier and (2) ions
of the Group Ib metal. The latices which are provided
with bacterial protection utilizing the technique of
this invention are comprised of (1) water, (2) at
least one polymer, (3) an emulsifier and (4) ions of
the Group Ib metal.
The polymer in the latex can be any polymeric
material which is capable of being in latex form. The
polymer will generally be a homopolymer or copolymer
of conjugated diolefin , i, acrylic monomers,
vinyl acetate monomers, vinyl pyridine, vinylidene
monoaromatic monomers, vinyl aromatic r~n( ~r~ or o!-
olefin monomers. The latex can, of course, be a latex
of a rubbery polymer. 3~or instance, the latex can be
~ _ _ _ _ . . , . ... . . . . _ _ .. _ _ . _ .
~ 5 - 2 1 80889
a styrene-butadiene rubber latex, a carboxylated
styrene-butadiene rubber latex, a poly~tA~l; Pn.s rubber
latex, a nitrile rubber latex or a carboxylated
nitrile rubber latex. The latex can also be a
5 polyvinyl chloride (PVC) latex.
The latices which can be treated by the process
of this invention can contain a wide variety of types
of emulsifiers or surfArtAntq. By the same token,
virtually any type of emulsifier can be treated
10 ut; l; 7; ng the techni(aue of this invention. For
instance, anionic emulsif iers, cationic emulsif iers,
nonionic emulsif iers or amphoteric emulsif iers can be
provided with bacterial resistance by adding ions of
Group Ib metals thereto. Some representative examples
15 of anionic emulsifiers which can be used include
carboxylates having the structural formula:
1~
R--CH2--C--0--Na
wherein R represents an alkyl group which contains
f rom about 10 to about 16 carbon atoms; alkylbenzene
sulfonates having the structural formula:
R~S03Na
wherein R represents an alkyl group which rf~ntAInq
30 from about 10 to about 13 carbon atoms; alkane
sulfonates having the structural formula:
R2
R1 CH--SO3Na
' ~ - 6 - 2180~89
wherein R1 and R2 represent alkyl groups which can be
the same or dif f erent and which contain f rom about 11
to about 17 carbon atoms; alpha-olefin sulfonates
having the structural formula:
H3C ~ CH~mCH=C~I~ CH~nS03Na
wherein n and m represent integers with the sum of n
and m being from about 9 to about 15; fatty alcohol
sulfates having the structural formula:
R--CH2--0--S03Na
wherein R represents an alkyl group having from about
11 to about 17 carbon atoms; and oxo- alcohol ether
sulfates having the structural formula:
R'
R--CH--CX2--0 ~CH~ CH~ O~nS03Na
wherein R and R' represent alkyl groups rrn~;n;ng
from about 11 to about 13 carbon atoms and wherein n
is an integer f rom 1 to about 4 .
In many cases, salts of alkyl sulfates, alkyl
sulfonates and alkyl rhrsph~ will be utilized as
the emulsifier. The alkyl groups in these compounds
generally contain from 1 to 30 carbon atoms. Normally
the alkyl groups in these sur~rt~n~ will contain
from 8 to 20 carbon atoms. The surfactant utilized
will normally be a sodium, potassium, magnesium or
amm~onium salt. Sodium lauryl sulfate, ~mmmn;llm lauryl
sulfate, sodium dodecyl benzene sulfonate and sodium
dodecyl sulfate are some representative examples of
widely used emulsif iers .
Generally from about 0 . 005 phm (parts per 100
parts of monomer) to about 5 phm of emDlsif ier is
' ~ 2180889
-- 7
utilized in preparing latices. In most cases, it is
preferred for latex to contain from about .1 phm to 1
phm of emulsifier. It i8 normally more preferred for
latex to contain from about .4 phm to about .8 phm of
emulsif ier. The precise amount of emulsif ier required
in order to attain optimal results will, of course,
vary from one latex to another and with the specific
emulsifier which is chosen. Xowever, persons skilled
in the art will be able to easily ascertain the
specific amount of emulsifier required in order to
attain optimal results.
~atices with extremely low solids contents to
latices with extremely high solids cnntPn~ can be
treated by utilizing the techniques of this invention.
For instance, the treated latex could have a solids
content which is as low as about 1 percent to as high
as about 70 percent. The latex will typically have a
solids content which is within the range of about 30
percent to about 60 percent. The latex will more
typically have a solids content which is within the
range of about 45 percent to about 55 percent.
This method of this invention can be carried out
by simply adding ions of a Group Ib metal to the
latex. This will typically be done shortly after the
latex is synthesized. ~Iowever, the Group Ib metal
ions can be added to the water utilized in making the
latex before the latex is made. On the other hand,
the Group Ib metal ions can be added to the latex at
any time in the storage life of the latex.
In an alternative embodiment of this invention,
the Group Ib metal is added to the emulsifier ~lt; 1; 7t~t
in making the emulsion. This approach offers the
advantage of providing the emulsif ier system with
bacterial protection prior to being employed in making
the emulsion. In other words, the Group Ib metal ions
serve the dual function of both protecting the
2 1 80889
-- 8
emulsif ier system and subsequently protecting the
latex made therewith. Due to the fact that the level
of Group Ib metal ions will be diluted in making the
emulsion in cases where this approach is employed, it
5 may be desirable to add a higher level of Group Ib
metal ions to the emulsifier system initially. On the
other hand, additional Group Ib metal ions can be
added to the latex to attain the degree of bacterial
resistance which is desired.
The Group Ib metal ions will normally be copper
ions or silver ions for economic reasons. It is also,
of course, possible to utilize a combination of silver
ions and copper ions. Silver ions are normally most
preferred. However, copper ions may be preferred in
15 cases where copper ions are ~l~; l; 7~1 as part of the
m polymerization initiator system. The metal
ions can be added to the emulsif ier or latex in the
form of soluble compounds or as solutions of soluble
compounds. For instance, silver acetate, silver
20 bromide, silver carbonate, silver chlorate, silver
chloride, silver citrate, silver fluoride, silver
iodate, silver lactate, silver nitrate, silver
nitrite, silver perchlorate or silver sulfide can be
added directly to the latex. In the alternative,
25 aqueous solutions of these compounds can be made with
the solution being added to the latex. An
electrolytic process for adding Group Ib metal ions to
the latex can also be utilized.
The treated latex will normally contain f rom
30 about 1 ppm to about 50 ppm ~parts per million) of the
Group Ib metal ions. In cases where the latex is
treated with silver ions, it will more typically
contain from about 2 ppm to about 10 ppm of silver
ions. In most cases, it is preferred for the treated
35 latex to contain from about 3 ppm to about 5 ppm of
silver ions. In cases where copper ions are used,
2 1 8~889
g
higher concentrations within the range of about 5 ppm
to about 50 ppm will normally be required. In cases
where copper ions are used, it i8 typically preferred
for the treated latex to contain from about 8 ppm to
5 about 30 ppm of the copper ions. It is normally more
preferred for such treated latices to contain from
about 10 ppm to about 20 ppm of copper ions. Treated
emulsifier systems will normally contain at least
about 10 ppm of copper ions or at least about 2 ppm of
10 silver ions .
To attain the most cost-effective level of --
protection against bacterial growth, a com~bination of
Group Ib metal ions and organic chemical bactericide
will typically be added to the latex. For instance,
from about 2 ppm to about 4 ppm of silver ions can be
added to the latex with about 300 ppm to 1000 ppm of
an organic chemical bactericide. In some cases, it
may be desirable to add more than one organic chemical
bactericide to the latex in conjunction with the Group
Ib metal ions. Numerous organic chemical bactericides
which can be used in conjunction with Groups Ib metal
ions are commercially available. Some representative
of suitable organic chemical bactericides include: 2-
methyl-4,5-trimethylene-4-isothiazolin-3-one which is
sold by Zeneca as an aqueous solution under the
tr~lQn~m~ Promexal X50, 1,2-dibromo-2,4-dicyanobutane
which is sold by Calgon Corporation under the
tr~Pn;lm~ Tektamer 38~V, 2-bromo-2-nitro-1, 3-
propanediol which is sold by Nalco under the trs
Nalco 92RU093, methylene bis (thiocyanate) which is
sold in a mineral oil and water emulsion by Nalco
under the tradename Nalco 5793, 1,2-dibromo-2,4-
dicyano-butane which is sold by Calgon Corporation
under the tradename Biochek 430, and 2-bromo-2-nitro-
1, 3 -propanediol which is sold by Nalco under the
~r~ n~mf~ Nalco VX5357 as mixture with 2-methyl-4-
21 80889
- 10 -
isothiazolin-3-one and 5-chloro-2-methyl-4-
isothiazol in - 3 - one .
This invention is illustrated by the following
examples which are merely for the purpose of
5 illustration and are not to be regarde~ as limiting
the scope of the invention or the manner in which it
can be practiced. Unless specifically indicated
otherwise, all parts and percentages are given by
weight .
~ rr~ples 1-4
In this series of experiments, a carboxylated
styrene-b~t~ n~o rubber latex which was treated with
4 ppm of silver ions was compared for bacterial
15 protection with a control and two latices which were
treated with standard organic chemical bactericides.
In the procedure used, quart (0.9464 liter) samples
cnnt~;n;ng the bactericides were prepared and aged 20
days in a 37~C water bath. One hundred wet grams of
20 the aged latices were inoculated with 1 cc of latex
cnnt;i;n;n~ about 6,000,000 cfu/cc of mixed wild strain
bacteria. The inoculated latices were tested for
active bacteria after 4 and 24 hours of aging at 37CC
and were then reinoculated with the spoiled latex.
25 The latices were tested again 24 hours after the
second inoculation.
In this series of experiments, Example 1 was
conducted as a control and did not contain any
bactericide or Group Ib metal ions. The latices
30 tested in Example~ 2 and 3 cnnt~;n~o~l the combination
of commercially available bactericides shown in Table
I. The latex tested in Example 4 c~mt;q; n~l 4 ppm of
silver ions which was introduced as a O.1 percent
silver nitrate solution. The results of these tests
35 are shown in Table I.
2~ 80889
- 11 -
Table I
Bactericide Evaluations
Bactericide 4 hrs 24 hrs 48 hrs
Tektamer 38LV1 -1000 ppm 2.8x104 0 0
Nalco 92RU0932 - 150 ppm cfu/cc cfu/cc cfu/cc
5 2 Nalco 57933 - 600 ppm 9 . 9X104 3 . 2x10~ 4 . 2x1o6
Nalco 92RU0932 - 200 ppm cfu/cc cfu/cc cfu/cc
3 Silver ions - 4 ppm 1. OxlO2 o o
cfu/cc cfu/cc cfu/cc
4 None 2 . 8x1o6 6 . 4x1o6 6 . 0x1o~
cfu/cc cfu/cc cfu/cc
1Tektamer 38LV biocide is a multicomponent dispersion
which contains 25 percent by weight 1,2-dibromo-2,4-
dicyanobutane .
2Nalco 92RU093 bactericide is an aqueou3 bLI ni~ ed
nitroalcohol which is comprised of 2-bromo-2-nitro-
1, 3 -propanediol in dipropylene glycol monoethyl ether.
3Nalco 5793 preservative is methylene bis (thiocyanate)
in a mineral oil and water emulsion.
This experiment shows that the latex which was
treated with 4 ppm silver ions was protected as well
as the latex which was treated with 1000 ppm of
Tektamer 38LV bactericide and 159 ppm of Nalco 92RU093
bactericide. The latex which was treated with 600 ppm
of Nalco 5793 bactericide and 200 ppm of Nalco 92RU093 ==
exhibited severe bacterial growth. The latex which
was untreated also showed severe bacterial growth.
Exam~les 5 - 9
In thi& series of experiments, quart (0.9464
liter) samples of fresh carboxylated styrene-butadiene
rubber latex c~n~;n;ng various bactericides were
prepared for testing. In the procedure used, 100 gram
samples of the latices were repeatedly inoculated with
35 1.0 cc of a blend of six ~ ~nt~m;n~ted latices. The
2~ 80889
- 12 -
inoculated latices were stored in a 37~C water bath
and bacteria counts of the inoculated samples were
taken the next working day. The samples were again
inoculated with 1.0 cc of the c~lnt~ nAt~d latex with
5 bacteria counts again being taken the next working day
after being stored in the water bath at a temperature
of 37~C. This procedure was repeated until the
bactericides being tested failed. The bactericides
tested as well as the number of inoculations required
10 to cause failure are reported in Table II. The number
of days to failure is also reported in Table II.
Table II
Ex. Bactericide Inoculations Days
15 5 Biochek 4301 - 1500 ppm 13 21
6 Nalco VX53572 - 1500 ppm 24 35
7 Promexal X503 - 1000 ppm 16 25
8 Biochex 4301 - 750 ppm 16 25
Silver ions - 4 ppm
9 Silver ions - 4 ppm 7 12
1Biochek 430 microbicide is a multicomponent liquid
which r~f~ntA;nq about 24 weight percent 1,2-dlbromo-
2,4-dicyano-butane, less than 0.1 weight percent 5-
chloro-2-methyl-4-isothiazoline-3-one, and less than
0.1 weight percent 2-methyl-4-isoth;~7-~l;nl~-3-one.
2Nalco VX 5357 bactericide i8 an aqueous solution of
brominated nitroalcohol and substituted
isoth;A7~1 ;nl~nP which ~f)nt~;nq about 9.23 weight
percent 2-bromo-2-nitro-1,3-propanediol, about 0.08
weight percent 2-methyl-4-isoth;A7~lin-3-one, 0.23
weight percent 5 - chloro - 2 -methyl - 4 - isothiazol in - 3 - one .
3Promexal X50 biocide is an aqueous solution of 2-
methyl-4,5-trimethylene-4-isothiazolin-3-one.
As can be seen from Example 9 in Table II, the
latex which ct ntA~n~d only 4 ppm of silver ions as a
bactericide protected the latex until the seventh
2 1 80889
- 13 -
inoculation over a period of 12 days. Thus, the
silver ions alone provided the latex with protection
against bacterial growth. EIowever, Example 8 shows
that outstanding protection against bacterial growth
5 is provided by 11~; 1 7 ~ing a combination of silver ions
and organic chemical bactericide. In fact, the degree
of protection against bacterial growth exhibited in
Example 8 is better than the protection against
bacterial growth exhibited in Example 5 where twice as
10 much of the Biochek 430 bactericide was utilized.
r l eg 10-1~
The procedure described in Examples 5-9 was
repeated in this series of experiments except f or the
15 fact that latex samples which had been shelf aged for
one month were used rather than f resh latex samples .
The results of this testing are reported in Table III.
Table III
20 Ex. E~actericide Inoculations Days
10 ~iochek 430 - 1500 ppm 3 4
11 Nalco VX5357 - 1500 ppm 21 37
12 Promexal X50 - 1000 ppm 8 14
13 ~3iochex 430 - 750 ppm 14 26
Silver ions - 4 ppm
25 14 Silver ions - 4 ppm 5 8
15 Nalco VX5357 - 750 ppm 21 37
Silver ions - 2 ppm
16 Promexal X50 - 500 ppm 7 13
Silver ions - 4 ppm
As can be seen from Table III, the latex which
r~n~;n~-l only 4 ppm of silver ions as a bactericide
protected the latex until the f if th inoculation over a
period of eight days. Thus, the low level of silver
~ 21 8088~
- 14 -
ions again proved to provide the latex with a degree
of protection against bacterial growth. However,
Examples 13, 15 and 16 showed that outstanding
protection against bacterial growth is provided by
5 llt;l;7;ng a combination of silver ions and organic
rh~m;r~l bactericide. In fact, the degree of
protection against bacterial growth exhibited in
Example 13 is much better than the protection against
bacterial growth exhibited in Example 10 where twice
as much of the i3iochek 430 bactericide wag llt; 1; 7
Example 15 showg that 750 ppm of Nalco VX5357
bactericide used in conjunction with only 2 ppm of ~=
silver ions provides the same level of inhibition to
bacterial growth as does the use of twice as much
15 Nalco VX5357 bactericide without silver ions.
Examples 12 and 16 show that the amount of Promexal
X50 bactericide can be cut in half if used in
conjunction with only 2 ppm of silver ions without a
significant loss in protection against bacterial
2 0 growth .
r les 17-21
The procedure described in Examples 5 - 9 was
repeated in this series of experiments except for the
25 fact that latex samples which had been shelf-aged for
two months were used rather than fresh latex samples.
The re~ulti~ Or this te~tir,sl ~re reported 1n Table IV.
21 80889
- 15 -
Table IV
Bx.Bactericide Inoc~ t; nn~ Days
17 Biochek 430 - 1500 ppm 10 13
18 Nalco VX5357 - 1500 ppm 10+ 13+
19 Promexal X50 - 1000 ppm 9 12
Biochex 430 - 750 ppm 9 12
Silver ions - 4 ppm
21 Silver ions - 4 ppm
Example 20 again shows that outstanding
protection against bacterial growth is provided by
utilizing a combination of silver ions and an organic
chemical bactericide. In fact, the degree of
protection against bacterial growth exhibited in
Example 20 is essentially the same as the protection
against bacterial growth ex_ibited in Example 17 where
twice as much of the Biochek 430 bactericide was
utilized. Example 21 does not show good protection
against bacteria growth which may be attributable to
the level of silver ions ~;m~n;~h;n~ over time because
of precipitation of the silver nitrate which was
utilized as the source of silver ions.
Exam~les 22 - 2 6
The procedure described in Examples 5-9 was
repeated in this series of experiments except ~or the
fact that latex samples were inoculated with 0.1 cc
portions of the l-nnt;~m; n~ted latex sample rather than
1.0 cc portions of the cnnt~m;n~ted latex samples.
The results oî this testing are reported in Table V.
2~ 8~88q
- 16 -
Table V
Ex.Bactericide Inoculations Days
22Biochek 430 - 1500 ppm 19 30
23 Nalco VX5357 - 1500 ppm 24+ 35+
24 Promexal X50 - 1000 ppm 24 35+
Biochex 430 - 750 ppm 10 17
Silver ions - 4 ppm
26 Silver ions - 4 ppm 6 11
This series of experiments shows the same general
trends as was experienced. in Examples 5-9 .
Exam~les 27-31
The procedure descrioed in Examples 5 - 9 was
15 repeated in this series of experiments except f or the
fact that latex samples were inoculated with 0.1 cc
portions of the c~nt~minAted latex sample rather than
1.0 cc portions of the c~nt~m~nAted latex samples and
except for the fact that latex samples which had ~een
20 shelf-aged for one month were used rather than fresh
latex samples. The results of this testing are
reported in Table VI.
Ta~le VI
25 Ex. Bactericide Inoculations Days
27 Biochek 430 - 1500 ppm 3 4
28 Nalco VX5357 - 1500 ppm 22+ 37+
29 Promexal X50 - 1000 ppm 22+ 37+
Biochex 430 - 750 ppm 14 26
Silver ions - 4 ppm
30 31 Silver ions - 4 ppm 7 13
~ - 17 2 1 8o889
This ~eries of experiments shows the same general
tread as were shown in Examples 5 - 9 . As can be seen
from Example 31, the latex which crnt~;n~d only 4 ppm
of silver ions as a bactericide protected the latex
5 until the seventh inoculation over a period of 13
days. Thus, the silver ions alone provided the latex
with protection against bacterial growth. However,
Example 30 again shows that outstanding protection
against bacterial growth is provided by ~t;l;7;ng a
10 rr,mh;n~t;on of silver ions and organic chemical
bactericide . In f act, the degree of protection
against bacterial growth exhibited in Example 30 is
better than the protection against bacterial growth
exhibited in Example 27 where twice as much of the
15 Biochek 430 bactericide was utilized.
Exam~ 1 e 3 2
In this experiment copper ions were evaluated as
a bactericidal agent in sodium lauryl sulfate
20 emulsifier. The sodium lauryl sulfate surfactant was
sterilized by heating to 70~C for 10 minutes because
the ~ample received from the vendor already contained
bacteria. Known strains of bacteria were then added
to the sodium lauryl sulfate sample. The bacteria
25 added rnnt;l;n-~-l equal amounts of the following test
organisms: ps~ aeruginosa, staphylococcus
aureus, escherichia coli, candida alabicans, and
aspergillus niger.
Copper nitrate was added to three separate
30 samples o~ the r~nt~m;n~ted sodium lauryl sulfate
surfactant to provide concentrat;r-n~ of copper ion of
10 ppm, 25 ppm and 100 ppm. The copper ion was
detPrm;nPd to be effective on the basis that (1) the
concentration of viable bacteria was reduced to 0.1
35 percent of the initial rrnrPntr~tion by the fourteenth
day, (2) the rrn~Pntr~t;rn of viable yeast and molds
~ - 18 - 2180889
L~ ~n~fl at or below the initial rf~ncPntration for
fourteen days, and (3) the concentration of the
challenging organisms Ll i TlP~l at or below these
designated levels for a 28 day period.
Example 33
The procedure described in Example 32 was
repeated in this experiment except for the fact that a
sodium alkylphenoxyether sulfate emulsifier was used
10 in place of the sodium lauryl sulfate emulsifier used
in Example 32. In this experiment, the copper nitrate
was also determined to be effective as a bactericidal
agent for the sodium alkylphenoxyether sulfate
emulsifier at r(-nrf~n~r~t;ons of 25 ppm and 10 ppm.
While certain representative embo~l;m~on~ and
details have been shown f or the purpose of
illustrating the subject invention, it will be
apparent to those skilled in this art that various
changes and modif ications can be made therein without
20 departing from the scope of the subject invention.
