# Patent

## Title
Microbicidal composition

## Abstract

An aqueous microbicidal composition having two components. The first component is a nonionic surfactant with structure: R1O(CH2CH(CH3)O)5(CH2CH2O)9H, where R1 is a C8 alkyl group. The second component is phenoxyethanol. The weight ratio of the nonionic surfactant to phenoxyethanol is from 1:1 to 1:18.2766.

## Background
This invention relates to microbicidal compositions containing 2-phenoxyethanol and a surfactant.
A composition containing 5-chloro-2-methylisothiazolin-3-one, 2-methylisothiazolin-3-one and a nonionic dispersant is disclosed in U.S. Pat. No. 4,295,932. The composition contains a 3:1 mixture of 5-chloro-2-methylisothiazolin-3-one and 2-methylisothiazolin-3-one, and a copolymer of ethylene oxide and propylene oxide which appears to have the same composition as PLURONIC L61 or TERGITOL L61 dispersant. However, there is a need for combinations of microbicides having synergistic activity against various strains of microorganisms to provide effective control of the microorganisms. Moreover, there is a need for such combinations containing lower levels of individual microbicides for environmental and economic benefit. The problem addressed by this invention is to provide such synergistic combinations of microbicides.
STATEMENT OF THE INVENTION
The present invention is directed to a synergistic microbicidal composition comprising: (a) a nonionic surfactant with structure:

R1O(CH2CH(CH3)O)5(CH2CH2O)9H

where R1 is a C8 alkyl group; and (b) phenoxyethanol; wherein a weight ratio of said nonionic surfactant to phenoxyethanol is from 1:1 to 1:18.2766.

The present invention is further directed to a synergistic microbicidal composition comprising: (a) a nonionic surfactant with structure:

R2O(CH2CH(CH3)O)3(CH2CH2O)xH

where R2 is a mixture of C8-C14 linear alkyl groups and x is an integer from 5 to 7; and (b) phenoxyethanol; wherein a weight ratio of said nonionic surfactant to phenoxyethanol is from 1:0.1999 to 1:36.5897.



DETAILED DESCRIPTION OF THE INVENTION
“Phenoxyethanol” is 2-phenoxy-1-ethanol (CAS No. 122-99-6). As used herein, the following terms have the designated definitions, unless the context clearly indicates otherwise. The term “microbicide” refers to a compound capable of inhibiting the growth of or controlling the growth of microorganisms; microbicides include bactericides, fungicides and algaecides. The term “microorganism” includes, for example, fungi (such as yeast and mold), bacteria and algae. The following abbreviations are used throughout the specification: ppm=parts per million by weight (weight/weight), mL=milliliter. Unless otherwise specified, temperatures are in degrees centigrade (° C.), references to percentages are percentages by weight (wt %) and amounts and ratios are on an active ingredient basis, i.e., total weight of phenoxyethanol and the nonionic surfactant. Numbers of polymerized units of propylene oxide or ethylene oxide are number averages.
Preferably, the weight ratio of the nonionic surfactant with structure: R1O(CH2CH(CH3)O)5(CH2CH2O)9H, where R1 is a C8 alkyl group, to phenoxyethanol is from 1:1.5992 to 1:18.2766; preferably from 1:1 to 1:2. Preferably, the C8 alkyl group is 2-ethylhexyl. The present invention is further directed to a method for inhibiting the growth of microorganisms in an aqueous medium by adding to said aqueous medium said nonionic surfactant and phenoxyethanol; wherein the weight ratio of the nonionic surfactant to phenoxyethanol is from 1:1 to 1:18.2766. The present invention is further directed to a method for inhibiting the growth of P. aeruginosa in an aqueous medium by adding to said aqueous medium said nonionic surfactant and phenoxyethanol; wherein the weight ratio of the nonionic surfactant to phenoxyethanol is from 1:1.5992 to 1:18.2766.
When a nonionic surfactant with structure: R2O(CH2CH(CH3)O)3(CH2CH2O)xH, where R2 is a mixture of C8-C14 linear alkyl groups and x is an integer from 5 to 7, is combined with phenoxyethanol, preferably the C8-C14 linear alkyl groups comprise from 50 to 85 wt % C8-C10 linear alkyl groups and 15 to 50 wt % C12-C14 linear alkyl groups, preferably from 60 to 75 wt % C8-C10 linear alkyl groups and 25 to 40 wt % C12-C14 linear alkyl groups, preferably about 70 wt % C8-C10 linear alkyl groups and about 30 wt % C12-C14 linear alkyl groups. Preferably, the linear alkyl groups are derived from seed oil. Preferably x is 5 or 7. When x is 5, preferably the weight ratio of the nonionic surfactant to phenoxyethanol is from 1:0.1999 to 1:36.5877. When x is 7, preferably the weight ratio of the nonionic surfactant to phenoxyethanol is from 1:0.7996 to 1:27.4377, preferably from 1:1 to 1:6. The present invention is further directed to a method for inhibiting the growth of microorganisms in an aqueous medium by adding to said aqueous medium said nonionic surfactant and phenoxyethanol; wherein the weight ratio of said nonionic surfactant to phenoxyethanol is from 1:0.1999 to 1:36.5897. The present invention is further directed to a method for inhibiting the growth of S. aureus in an aqueous medium by adding to said aqueous medium a surfactant with structure: R20(CH2CH(CH3)o)3(CH2CH2O)5H, where R2 is a mixture of C8-C14 linear alkyl groups, and phenoxyethanol; wherein the weight ratio of the nonionic surfactant to phenoxyethanol is from 1:0.1999 to 1:36.5897. The present invention is further directed to a method for inhibiting the growth of mold, preferably A. niger, in an aqueous medium by adding to said aqueous medium a surfactant with structure: R2O(CH2CH(CH3)o)3(CH2CH2O)5H, where R2 is a mixture of C8-C14 linear alkyl groups, and phenoxyethanol; wherein the weight ratio of the nonionic surfactant to phenoxyethanol is from 1:0.3998 to 1:13.7006. The present invention is further directed to a method for inhibiting the growth of S. aureus in an aqueous medium by adding to said aqueous medium a surfactant with structure: R2O(CH2CH(CH3)o)3(CH2CH2O)7H, where R2 is a mixture of C8-C14 linear alkyl groups, and phenoxyethanol; wherein the weight ratio of the nonionic surfactant to phenoxyethanol is from 1:0.7996 to 1:27.4377. In each of the aforementioned methods, the preferred compositions of the linear alkyl groups are as stated earlier in this paragraph.
Preferably, each of the synergistic microbicidal compositions is substantially free of microbicides other than the nonionic surfactant and phenoxyethanol, i.e., it has less than 1 wt % of microbicides other than the nonionic surfactant and phenoxyethanol based on total weight of active ingredients, preferably less than 0.5 wt %, preferably less than 0.2 wt %, preferably less than 0.1 wt %. Preferably, when the nonionic surfactant and phenoxyethanol are added to an aqueous medium, the medium is substantially free of other microbicides, i.e., it has less than 1 wt % of microbicides other than the nonionic surfactant and phenoxyethanol based on total weight of active ingredients, preferably less than 0.5 wt %, preferably less than 0.2 wt %, preferably less than 0.1 wt %.
The compositions of this invention may contain other ingredients, e.g., defoamers and emulsifiers. The microbicidal compositions of the present invention can be used to inhibit the growth of microorganisms or higher forms of aquatic life (such as protozoans, invertebrates, bryozoans, dinoflagellates, crustaceans, mollusks, etc) by introducing a microbicidally effective amount of the compositions into an aqueous medium subject to microbial attack. Suitable aqueous media are found in, for example: industrial process water; electrocoat deposition systems; cooling towers; air washers; gas scrubbers; mineral slurries; wastewater treatment; ornamental fountains; reverse osmosis filtration; ultrafiltration; ballast water; evaporative condensers; heat exchangers; pulp and paper processing fluids and additives; starch; plastics; emulsions; dispersions; paints; latices; coatings, such as varnishes; construction products, such as mastics, caulks, and sealants; construction adhesives, such as ceramic adhesives, carpet backing adhesives, and laminating adhesives; industrial or consumer adhesives; photographic chemicals; printing fluids; household products, such as bathroom and kitchen cleaners; cosmetics; toiletries; shampoos; soaps; personal care products such as wipes, lotions, sunscreen, conditioners, creams, and other leave-on applications; detergents; industrial cleaners; floor polishes; laundry rinse water; metalworking fluids; conveyor lubricants; hydraulic fluids; leather and leather products; textiles; textile products; wood and wood products, such as plywood, chipboard, flakeboard, laminated beams, oriented strandboard, hardboard, and particleboard; petroleum processing fluids; fuel; oilfield fluids, such as injection water, fracture fluids, and drilling muds; agriculture adjuvant preservation; surfactant preservation; medical devices; diagnostic reagent preservation; food preservation, such as plastic or paper food wrap; food, beverage, and industrial process pasteurizers; toilet bowls; recreational water; pools; and spas.
The specific amount of the microbicidal compositions of this invention necessary to inhibit or control the growth of microorganisms in an application will vary. Typically, the amount of the composition of the present invention is sufficient to control the growth of microorganisms if it provides from 1,000 to 20,000 ppm (parts per million) active ingredients of the composition. It is preferred that the active ingredients (i.e., nonionic surfactant and phenoxyethanol) of the composition be present in the medium to be treated in an amount of at least 2,000 ppm, preferably at least 3,000 ppm, preferably at least 4,000 ppm. It is preferred that the active ingredients of the composition be present in the locus in an amount of no more than 16,000 ppm, preferably no more than 14,000 ppm, preferably no more than 12,000 ppm, preferably no more than 10,000 ppm, preferably no more than 8,000 ppm, preferably no more than 7,000 ppm. In a method of this invention, a composition is treated to inhibit microbial growth by adding, together or separately, the nonionic surfactant and phenoxyethanol, in amounts that would produce the concentrations indicated above.
EXAMPLES
Surfactants and biocides were evaluated for synergy by determining the synergy index (S.I.) of the combination. Synergy index was calculated based on minimum inhibitory concentrations (MIC) of two antimicrobial compounds (A and B) alone and in combinations. The tests organisms were Gram negative bacteria (Pseudomonas aeruginosa ATCC #15442),
Gram positive bacteria (Staphylococcus aureus ATCC #6538), yeast (Candida albicans ATCC#10203) and mold (Aspergillus niger ATCC#16404). Contact time for the bacteria was 24 and 48 hours, yeast was 48 and 72 hrs, and 3 and 7 days for mold. The test was carried out in 96 well microtiter plates.

    Surf. A R1O(CH2CH(CH3)o)5(CH2CH2O)9H, where R1 is 2-ethylhexyl
    Surf. D R2O(CH2CH(CH3)o)3(CH2CH2O)5H
    Surf. E R2O(CH2CH(CH3)o)3(CH2CH2O)7H
    In Surf. D and Surf. E, R2 is a mixture of C8-C14 linear alkyl groups (70% C8-C10 linear alkyl and 30% C12-C14 linear alkyl)


Inoculums Used










Inoculum Size of organisms ( CFU/ml )















Candida



Staphylococcus
Pseudomonas
Aspergillus
albicans


Sur-
aureus
aeruginosa
niger
ATCC#


factants
ATCC# 6538
ATCC # 15442
ATCC# 16404
10203





Surf. A
1.156E+06
8.134E+07
1.156E+06
1.156 +06


Surf. D
1.808E+05
1.156E+08
1.156E+06
5.726E+05


Surf. E
1.808E+06
5.727E+07
5.726E+05
1.808E+06
















TABLE 4







Media Used


Media Used for testing










Staphylococcus
Pseudomonas
Aspergillus
Candida


aureus
aeruginosa ATCC #
niger
albicans


ATCC# 6538
15442
ATCC# 16404
ATCC#10203





10% Tryptic soy
10% Tryptic soy
Potato dextrose
Potato dextrose


broth
broth
broth
broth









The pH of the Triptic soy broth was 7.3 and the Potato dextrose broth was 5.1.
The test results for demonstration of synergy of the MIC combinations are shown in the tables below. Each table shows the results for combinations of two components against the microorganisms tested with incubation times; the end-point activity in ppm measured by the MIC for compound A alone (CA), for component B alone (CB), and the mixture (Ca) and (Cb); the calculated SI value; and the range of synergistic ratios for each combination tested. SI is calculated as follows:

Ca/CA+Cb/CB=Synergy Index (“SI”)

Wherein:

    
    
        CA=concentration of compound A in ppm, acting alone, which produced an end point (MIC of Compound A).
        Ca=concentration of compound A in ppm, in the mixture, which produced an end point.
        CB=concentration of compound B in ppm, acting alone, which produced an end point (MIC of Compound B).
        Cb=concentration of compound B in ppm, in the mixture, which produced an end point.

When the sum of Ca/CA and Cb/CB is greater than one, antagonism is indicated. When the sum is equal to one, additivity is indicated, and when less than one, synergism is demonstrated.

    
    


The ratio ranges at which phenoxyethanol and the surfactants were tested are as summarized in the following tables:










Phenoxyethanol with Surf. A











Organism
ATCC#
From
To
Ratio Range














S. aureus
6538
2.0:20,000
10,000:218.75
1:0.0001-1:45.7143


A. niger
16404
0.2:20,000
 1,000:218.75
1:0.00001-1:4.5714 


C. albicans
10203
0.2:20,000
 1,000:218.75
1:0.00001-1:4.5714 


Ps. aeruginosa
15442
2.0:20,000
10,000:218.75
1:0.0001-1:45.7143



















Phenoxyethanol with Surf. E











Organism
ATCC#
From
To
Ratio Range














S. aureus
6538
2.0:20,000
10,000:218.75
1:0.0001-1:45.7143


A. niger
16404
0.2:20,000
 1,000:218.75
1:0.00001-1:4.5714 


C. albicans
10203
0.2:20,000
 1,000:218.75
1:0.00001-1:4.5714 


Ps. aeruginosa
15442
2.0:20,000
10,000:218.75
1:0.0001-1:45.7143



















Phenoxyethanol with Surf. D











S. aureus
ATCC#
From
To
Ratio Range














A. niger
6538
2.0:20,000
10,000:218.75
1:0.0001-1:45.7143


C. albicans
16404
2.0:20,000
10,000:218.75
1:0.0001-1:45.7143


Ps.
10203
2.0:20,000
10,000:218.75
1:0.0001-1:45.7143


aeruginosa






S. aureus
15442
2.0:20,000
10,000:218.75
1:0.0001-1:45.7143









    A: Surf. A
    B: Phenoxyethanol


















A. niger
ATCC#16404
No Synergy



C. albicans
ATCC#10203
No Synergy









    A: Surf. A
    B: Phenoxyethanol
    Media: 1/10 TSB
    Inoculum size: 8.134E+07CFU/ml















PPM AI MIC Values ( 24 hrs)












Test
Alone
Combination

Ratio













Organism
CA
CB
Ca
Cb
S.I.
(Ca:Cb)
















Ps. aeruginosa
>20000
4997
2500
3998
<0.93
1:1.5992


ATCC#15442
>20000
4997
1750
3998
<0.89
1:2.2846



>20000
4997
875
3998
<0.84
1:4.5691



>20000
4997
437.5
3998
<0.82
1:9.1383



>20000
4997
218.75
3998
<0.81
1:18.2766









    A: Surf. A
    B: Phenoxyethanol
    Media: 1/10 TSB
    Inoculum size: 1.156E-+06CFU/ml















PPM AI MIC Values ( 24 hrs)












Test
Alone
Combination

Ratio













Organism
CA
CB
Ca
Cb
S.I.
(Ca:Cb)
















S. aureus
>20000
8000
5000
5000
<0.88
1:1.0000


ATCC# 6538
>20000
8000
2500
5000
<0.75
1:2.0000



>20000
8000
1750
5000
<0.71
1:2.8571



>20000
8000
1750
6000
<0.84
1:3.4286



>20000
8000
875
6000
<0.79
1:6.8571









    A: Surf. D
    B: Phenoxyethanol
    Media: PDB
    Inoculum size: 1.156E+06















PPM AI MIC Values ( 3rd day)












Test
Alone
Combination

Ratio













Organism
CA
CB
Ca
Cb
S.I.
(Ca:Cb)
















A. niger
>20000
3998
5000
1999
<0.75
1:0.3998


ATCC#16404
>20000
3998
2500
1000
<0.38
1:0.4000



>20000
3998
2500
1999
<0.63
1:0.7996



>20000
3998
2500
2997
<0.87
1:1.1988



>20000
3998
1750
1999
<0.59
1:1.1423



>20000
3998
875
1999
<0.54
1:2.2846



>20000
3998
437.5
2997
<0.77
1:6.8503



>20000
3998
218.75
2997
<0.76
1:13.7006









    A: Surf. D
    B: Phenoxyethanol
    Media: PDB
    Inoculum size: 5.726E+05CFU/ml















PPM AI MIC Values ( 48 hrs)












Test
Alone
Combination

Ratio













Organism
CA
CB
Ca
Cb
S.I.
(Ca:Cb)





C. albicans
>20000
3998
2500
1999
<0.63
1:0.7996


ATCC#10203
>20000
3998
2500
2997
<0.87
1:1.1988



>20000
3998
437.5
1999
<0.52
1:4.5691









    A: Surf. D
    B: Phenoxyethanol
    Media: 1/10 TSB
    Inoculum size: 1.16E+05CFU/ml















PPM AI MIC Values ( 24 hrs)












Test
Alone
Combination

Ratio













Organism
CA
CB
Ca
Cb
S.I.
(Ca:Cb)
















Ps. aeruginosa
>20000
3998
2500
2997
<0.87
1:1.1988


ATCC#15442
>20000
3998
1750
2997
<0.84
1:1.7126



>20000
3998
875
2997
<0.79
1:3.4251



>20000
3998
437.5
2997
<0.77
1:6.8503



>20000
3998
218.75
1999
<0.51
1:9.1383









    A: Surf. D
    B: Phenoxyethanol
    Media: 1/10 TSB
    Inoculum size: 1.808E+05















PPM AI MIC Values ( 24 hrs)












Test
Alone
Combination

Ratio













Organism
CA
CB
Ca
Cb
S.I.
(Ca:Cb)
















S. aureus
>20000
9999
10000
1999
<0.70
1:0.1999


ATCC# 6538
>20000
9999
10000
2997
<0.80
1:0.2997



>20000
9999
10000
3998
<0.90
1:0.3998



>20000
9999
5000
6002
<0.85
1:1.2004



>20000
9999
5000
4997
<0.75
1:0.9994



>20000
9999
5000
3998
<0.65
1:0.7996



>20000
9999
5000
2997
<0.55
1:0.5994



>20000
9999
2500
8004
<0.93
1:3.2016



>20000
9999
1750
8004
<0.89
1:4.5737



>20000
9999
1750
6002
<0.69
1:3.4297



>20000
9999
1750
4997
<0.59
1:2.8554



>20000
9999
1750
3998
<0.49
1:2.2846



>20000
9999
1750
2997
<0.39
1:1.7126



>20000
9999
1750
1999
<0.29
1:1.1423



>20000
9999
875
8004
<0.84
1:9.1474



>20000
9999
875
6002
<0.64
1:6.8594



>20000
9999
875
4997
<0.54
1:5.7109



>20000
9999
875
3998
<0.44
1:4.5691



>20000
9999
875
2997
<0.34
1:3.4251



>20000
9999
437.5
2997
<0.32
1:6.8503



>20000
9999
437.5
3998
<0.42
1:9.1383



>20000
9999
437.5
4997
<0.52
1:11.4217



>20000
9999
437.5
6002
<0.62
1:13.7189



>20000
9999
437.5
8004
<0.82
1:18.2949



>20000
9999
218.75
4997
<0.51
1:22.8434



>20000
9999
218.75
6002
<0.61
1:27.4377



>20000
9999
218.75
8004
<0.81
1:36.5897









    A: Surf. E
    B: Phenoxyethanol


















A. niger
ATCC#16404
No Synergy



C. albicans
ATCC#10203
No Synergy









    A: Surf. E
    B: Phenoxyethanol
    Media: 1/10 TSB
    Inoculum size: 5.727E+07CFU/ml















PPM AI MIC Values ( 24 hrs)












Test
Alone
Combination

Ratio













Organism
CA
CB
Ca
Cb
S.I.
(Ca:Cb)
















Ps. aeruginosa
>20000
3998
2500
2997
0.87
1:1.1988


ATCC#15442
>20000
3998
1750
2997
0.84
1:1.7126



>20000
3998
875
2997
0.79
1:3.4251



>20000
3998
437.5
2997
0.77
1:6.8503









    A: Surf. E
    B: Phenoxyethanol
    Media: 1/10 TSB
    Inoculum size: 1.808E+06CFU/ml















PPM AI MIC Values ( 24 hrs)












Test
Alone
Combination

Ratio













Organism
CA
CB
Ca
Cb
S.I.
(Ca:Cb)
















S. aureus
>20000
8004
5000
3998
0.75
1:0.7996


ATCC# 6538
>20000
8004
5000
4997
0.87
1:0.9994



>20000
8004
2500
2997
0.50
1:1.1988



>20000
8004
2500
3998
0.62
1:1.5992



>20000
8004
2500
4997
0.75
1:1.9988



>20000
8004
2500
6002
0.87
1:2.4008



>20000
8004
1750
3998
0.59
1:2.2846



>20000
8004
1750
4997
0.71
1:2.8554



>20000
8004
1750
6002
0.84
1:3.4297



>20000
8004
875
3998
0.54
1:4.5691



>20000
8004
875
4997
0.67
1:5.7109



>20000
8004
875
6002
0.79
1:6.8594



>20000
8004
437.5
2997
0.40
1:6.8503



>20000
8004
437.5
3998
0.52
1:9.1383



>20000
8004
437.5
4997
0.65
1:11.4217



>20000
8004
437.5
6002
0.77
1:13.7189



>20000
8004
218.75
4997
0.64
1:22.8434



>20000
8004
218.75
6002
0.76
1:27.4377









The following biocides had no synergy against any organism tested when paired with the following surfactants:
Surf. A


    Sodium Benzoate, Tris Nitro


Surf. E


    DMDMH


Surf. D


    CS-1246, OPP, DMDMH


In the following combinations, the ratio of surfactant to biocide where synergy was observed were not commercially relevant, i.e., a ratio of 1:0.2 or greater (less biocide relative to surfactant). At these ratios, the biocide levels in a formulated product would be too low to be practical:
Surf. A


    DIDAC, IPBC


Surf. E


    CMIT/MIT, IPBC, OIT, TTPC, WSCP


Surf. D


    CMIT/MIT, OIT, DIDAC
    (MBIT, IPBC, WSCP were synergistic only at 1:0.05 or worse except for one data point)


Stability Testing
A solution of phenoxyethanol in 70% (v/v) isopropanol was made and diluted with surfactant to give the desired ratios of biocide to surfactant. Additional 70% isopropanol was added as needed to give a 33 wt % solution of phenoxyethanol. The samples were split into three vials. One vial was stored at room temperature, one was stored at 40 C and one was stored at 50 C. Samples were evaluated after a week to determine stability. Samples that were cloudy or highly discolored were determined to be unstable. In the data tables, a dash indicates that the formulation was stable.










Stability Data - 33% Phenoxyethanol (PE) in combination with


Surfactants - Day 1









Temperature













Room




Surfactant
PE:Surfactant
Temperature
40° C.
50° C.





Surf. D
1:1
—
—
—



1:6
Cloudy
—
—



1:27
Slightly cloudy
—
—


Surf. E
1:1
—
—
—



1:6
—
—
—



1:27
Slightly cloudy
—
—


Surf. A
1:1
—
—
—



1:2
—
—
—


Surf. B
1:1
—
—
—



1:2
—
—
—


POLYSORBATE
1:1
—
—
—


20
1:2
—
—
—



1:6
—
—
—



1:27
—
—
—


Disodium
1:1
Cloudy
Cloudy
Cloudy


cocoamphodiacetate
1:2
—
—
—



1:6
—
—
—



1:27
Slightly cloudy
—
—


TERGITOL L-62
1:1
—
—
—



1:2
—
—
—



1:6
Cloudy
—
—



1:27
Cloudy
—
—


TERGITOL 81
1:1
—
—
—



1:2
Cloudy
—
—



1:6
Cloudy
—
—



1:27
Cloudy
—
—


TERGITOL 15-S-7
1:1
—
—
—



1:2
—
—
—



1:6
—
—
—



1:27
Cloudy
—
—





* Surf. B is R1O(CH2CH(CH3)O)5(CH2CH2O)6H, where R1 is 2-ethylhexyl
















Stability Data - 33% Phenoxyethanol in combination with


Surfactants - Day 2









Temperature













Room




Surfactant
PE:Surfactant
Temperature
40° C.
50° C.





Surf. D
1:1
—
—
—



1:6
Cloudy
—
—



1:27
Slightly cloudy
—
—


Surf. E
1:1
—
—
—



1:6
—
—
—



1:27
Slightly cloudy
—
—


Surf. A
1:1
—
—
—



1:2
—
—
—


Surf. B
1:1
—
—
—



1:2
—
—
—


POLYSORBATE
1:1
—
—
—


20
1:2
—
—
—



1:6
—
—
—



1:27
—
Slightly
Slightly





cloudy
cloudy


Disodium
1:1
Cloudy
Cloudy
Cloudy


cocoamphodiacetate
1:2
—
—
—



1:6
—
—
—



1:27
Slightly cloudy
—
—


TERGITOL L-62
1:1
—
—
—



1:2
—
—
—



1:6
Cloudy
—
—



1:27
Cloudy
—
—


TERGITOL 81
1:1
—
—
—



1:2
Cloudy
—
—



1:6
Cloudy
—
—



1:27
Cloudy
—
—


TERGITOL 15-S-7
1:1
—
—
—



1:2
—
—
—



1:6
—
—
—



1:27
Cloudy
—
—



















Stability Data - 33% Phenoxyethanol in combination with


Surfactants - Day 7









Temperature













Room




Surfactant
PE:Surfactant
Temperature
40° C.
50° C.





Surf. D
1:1
—
—
—



1:6
Cloudy
—
—



1:27
Slightly cloudy
—
—


Surf. E
1:1
—
—
—



1:6
—
—
—



1:27
Slightly cloudy
—
—


Surf. A
1:1
—
—
—



1:2
—
—
—


Surf. B
1:1
—
—
—



1:2
—
—
—


POLYSORBATE
1:1
—
—
—


20
1:2
—
—
—



1:6
—
—
—



1:27
—
Slightly
Slightly





cloudy
cloudy


Disodium
1:1
Cloudy
Cloudy
Cloudy


cocoamphodiacetate
1:2
—
—
—



1:6
—
—
—



1:27
Slightly cloudy
—
—


TERGITOL L-62
1:1
—
—
—



1:2
—
—
—



1:6
Cloudy
—
—



1:27
Cloudy
—
—


TERGITOL 81
1:1
—
—
—



1:2
Cloudy
—
—



1:6
Cloudy
—
—



1:27
Cloudy
—
—


TERGITOL 15-S-7
1:1
—
—
—



1:2
—
—
—



1:6
—
—
—



1:27
Cloudy
—
—

## Claims

1. A synergistic microbicidal composition comprising: (a) a nonionic surfactant with structure:


R1O(CH2CH(CH3)o)5(CH2CH2O)9H


where R1 is a C8 alkyl group; and (b) phenoxyethanol; wherein a weight ratio of said nonionic surfactant to phenoxyethanol is from 1:1 to 1:18.2766.

2. The synergistic microbicidal composition of claim 1 in which said C8 alkyl group is 2-ethylhexyl.

3. A method for inhibiting the growth of microorganisms in an aqueous medium; said method comprising adding to said aqueous medium: (a) a nonionic surfactant with structure:


R1O(CH2CH(CH3)o)5(CH2CH2O)9H


where R1 is a C8 alkyl group; and (b) phenoxyethanol; wherein a weight ratio of said nonionic surfactant to phenoxyethanol is from 1:1 to 1:18.2766.

4. The method of claim 3 in which said C8 alkyl group is 2-ethylhexyl.

5. A synergistic microbicidal composition comprising: (a) a nonionic surfactant with structure:


R2O(CH2CH(CH3)o)3(CH2CH2O)xH


where R2 is a mixture of C8-C14 linear alkyl groups and x is an integer from 5 to 7; and (b) phenoxyethanol; wherein a weight ratio of said nonionic surfactant to phenoxyethanol is from 1:0.1999 to 1:36.5897.

6. The synergistic microbicidal composition of claim 5 in which said mixture of C8-C14 linear alkyl groups comprises from 60 to 75 wt % C8-C10 linear alkyl groups and 25 to 40 wt % C12-C14 linear alkyl groups.

7. The synergistic microbicidal composition of claim 6 in which x is 5.

8. The synergistic microbicidal composition of claim 6 in which x is 7 and said weight ratio is 1:0.7996 to 1:27.4377.

9. A method for inhibiting the growth of microorganisms in an aqueous medium; said method comprising adding to said aqueous medium: (a) a nonionic surfactant with structure:


R2O(CH2CH(CH3)o)3(CH2CH2O)xH


where R2 is a mixture of C8-C14 linear alkyl groups and x is an integer from 5 to 7; and (b) phenoxyethanol; wherein a weight ratio of said nonionic surfactant to phenoxyethanol is from 1:0.1999 to 1:36.5897.

10. The method of claim 9 in which. said mixture of C8-C14 linear alkyl groups comprises from 60 to 75 wt % C8-C10 linear alkyl groups and 25 to 40 wt % C12-C14 linear alkyl groups.