CA2180889A1 - Emulsifier system with resistance to bacterial growth - Google Patents

Abstract

The growth of bacteria in latex and emulsifiers is an age old problem. Chemical bactericides are of ten added to latex and emulsifiers to control the growth of bacteria therein. This invention discloses a technique for providing emulsifiers and latex with resistance to bacterial growth. It is based upon the discovery that ions of a metal from Group Ib of the Periodic Chart, such as copper, silver or gold, will provide emulsifiers and latex with resistance to bacterial growth The subject invention more specifically discloses an emulsifier system which consists essentially of (1) an emulsifier and (2) ions of a metal from Group Ib of the Periodic Chart. In most cases, the metal ions will be present in an amount which is within the range of about 1 ppm to about 50 ppm. As a general rule, copper ions or silver ions are preferred. Latices having resistance to bacterial growth can be made by simply utilizing such Group Ib metal-containing emulsifiers in the synthesis thereof. The present invention accordingly further reveals 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 emulsifier system which is comprised of (1) an emulsifier and (2) ions of a metal from Group Ib of the Periodic Chart.

Description

~ 218~889 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 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 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:

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 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 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-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 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 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 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~

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.

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 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.

Claims (20)

1. An emulsifier system which consists essentially of (1) an emulsifier and (2) ions of a metal from Group Ib of the Periodic Chart.

2. 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 emulsifier system which is comprised of (1) an emulsifier and (2) ions of a metal from Group Ib of the Periodic Chart.

3. A method for producing a latex having resistance to bacterial growth which comprises (1) polymerizing at least one monomer in an aqueous emulsion which is prepared utilizing 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.

4. A method as specified in claim 1 wherein the ions of the metal from Group Ib are copper ions.

5. A method as specified in claim 1 wherein the ions of the metal from Group Ib are silver ions.

6. A method as specified in claim 4 wherein said copper ions are present at a concentration of at least about 10 ppm.

7. A method as specified in claim 5 wherein said silver ions are present at a concentration of at least about 2 ppm.

8. A method as specified in claim 4 wherein said copper ions are present at a concentration which is within the range of about 10 ppm to about 50 ppm.

9. A method as specified in claim 4 wherein said silver ions are present at a concentration which is within the range of about 2 ppm to about 50 ppm.

10. A method as specified in claim 6 wherein the emulsifier is an anionic emulsifier.

11. A method as specified in claim 7 wherein the emulsifier is an anionic emulsifier.

12. A method as specified in claim 2 wherein the ions of a metal from Group Ib of the Periodic Chart are copper ions.

13. A method as specified in claim 2 wherein the ions of a metal from Group Ib of the Periodic Chart are silver ions.

14. A method as specified in claim 13 wherein the silver ions are present in said latex at a concentration which is within the range of about 1 ppm to about 50 ppm.

15. A method as specified in claim 13 wherein the silver ions are present at a concentration which is within the range of about 2 ppm to about 10 ppm.

16. A method as specified in claim 12 wherein the copper ions are present in said latex at a concentration which is within the range of about 5 ppm to about 50 ppm.

17. A method as specified in claim 12 wherein the copper ions are present at a concentration which is within the range of about 8 ppm to about 30 ppm.

18. A method as specified in claim 12 wherein the copper ions are present at a concentration which is within the range of about 10 ppm to about 20 ppm.

19. A method as specified in claim 3 wherein the organic chemical bactericide is present in said latex in an amount which is within the range of about 300 ppm to about 1000 ppm.

20. A method as specified in claim 19 wherein the ions of a metal from Group Ib of the Periodic Chart are copper ions.