Microbicidal isothiazolone microemulsions and their preparation

Microbicidal isothiazolone microemulsions and their preparation

ROHM AND HAAS COMPANY

C: 75389

MICROBICIDAL MICROEMULSION

This invention is concerned with microemulsions of isothiazolones of low water solubility. The microemulsions of the inventions upon dilution with water, remain as microemulsion. These microemulsions are useful in many applications, such as fungicides, slimicides, algaecides or bactericides in any locus.

Microemulsions are dispersions of one liquid phase in a second immiscible phase. They can be water continuous (o/w) or oil continuous (w/o) where oil denotes an organic liquid (or liquids) of low water solubility. An unique property of microemulsions is that the interfacial tension between the two phases is very low; much lower than can be measured with conventional instruments such as a DuNouy Tensiometer. This low interfacial tension results from very specific combinations of oil (water immiscible organic liquid) and surfactants and water and is manifested in that the particle size of the dispersed phase is extremely small, usually less than 1000A. Since this is small in relation to the wave length of visible light, microemulsions appear opalescent or optically clear. Microemulsions are stable toward phase separation for periods measured in years. This contrasts with the normal macroemulsion, where milky appearance results from emulsion particles being in the 1-20 range, and where phase separation will typically occur within hours to weeks after the emulsion is prepared.

Optimum solubilization of an oil to give an o/w microemulsion can occur within a narrow composition range of oil and surfactant and cosurfactant and water. A typical example is given in Microemulsion Theory and Practice, Ed. L.M. Prince, Academic Press (1977) describing the system £־xylene and sodium lauryl sulfate and pentanol and water. When the composition is outside the microemulsion range defined by a phase diagram, multiphase regions exist. The consequence is that dilution of a microemulsion composition with water usually leads to a macroemulsion or multiphase, which are unstable systems. In a practical sense it is desirable to define a microemulsion composition that will remain clear and not phase separate when further diluted in water.

An o/w micellar solution can result when a small amount of oil is added to an aqueous solution of surfactant and water. If the amount of surfactant is great in relation to the oil (say >5:1) the oil can migrate to the interior of the surfactant micelle without greatly disturbing it. This solubilizing of the oil can result in a clear micellar solution and will very often retain clarity when further diluted in water. Because of large excesses of surfactant, compositions to give solubilized solutions are not as critical as with microemulsions. A microemulsion represents a much more efficient way of solubilizing an oil.

US-A-4,567,161 discloses transparent microemulsions with active ingredients (e.g. pesticides, herbicides, pharmaceuticals) together with a phospholipid and a coemulsifier (glycerin ester).

US-A-4,568,480 discloses preparing microemulsions using alkoxylated phenols where the phenol hydrophobe is a multi-ring system connected by alkylinden groups and the ethoxylated alcohol contains an ester group. These are generally useful with or without any additional phosphate ester alkali metal

I salt surfactant to prepare microemulsions of cosmetics, toiletries and drugs.

EP-A-55,401 discloses the preparation of microemulsions of insecticides and acaricides using an ethoxylated phenol prepared by alkylating tolylethylphenol and phenol with £-methylstyrene.

DE-3,235,612-AI discloses cold stable aqueous microemulsions of agrochemical pesticides, household pest control agents and pharmaceuticals using an emulsifier which is a mixture of alkylaryl polyglycol and an alkylarylsulfonate salt.

EP-A-092,457 discloses wood preservation concentrates containing a preservative and insecticides and fungicides formulated with an anionic emulsifier and a coemulsifier such as butoxy ethanol or diethylene glycol monobutyl ether. When further diluted these microemulsions form translucent to opaque dilutions.

US-A-4,146,499 discloses a method for preparing microemulsion.

Japanese Patent Application 52,122-628 discloses oil-in-water microemulsions where insecticides are emulsified with a nonionic surfactant.

EP-A-160,182 discloses microemulsions of a synthetic pyrethroid insecticide with a sulfonate anionic surfactant and multi-ring phenol ethoxylates.

US-A-3,683,078 discloses transparent solutions of various pesticides using relatively high levels of various anionic and ethoxylated or propoxylated phenols.

DE 2328192 discloses a microemulsion of <5% of a water insoluble herbicide with an emulsifier and a hydrotrope.

We have now found oil-in-water microemulsions of certain isothiazolones of low water solubility which are useful as biocides. By low water solubility is meant that the material is soluble in water at less than 1% by weight (at normal temperature and pressure).

The microemulsions of the invention are prepared by combining specifically defined amounts of isothiazolone, anionic surfactant, cosurfactant, polyoxyethylene/polyoxypropylene block copolymer, and water.

Isothiazolones of low water solubility are often prepared as a solution of isothiazolone in a water-miscible organic solvent such as propylene glycol. These concentrates are further diluted by the user in water or various aqueous based media to control growth of microorganisms. This approach sometimes has the disadvantage of poor homogeneity of the isothiazolone in the dilution when the solubility of the isothiazolone is exceeded. Often it is desirable to market the isothiazolone at active ingredient levels (Al) of only several percent in the concentrate to be diluted. This requires a large amount of organic solvent per Al unit. A water based concentrate would have substantial cost advantage and environmental advantages by replacing all or most of the organic solvent with water. A microemulsion form of the isothiazolone which would remain a microemulsion upon dilution would overcome these drawbacks.

The presence of such amounts of such water miscible solvent as is necessary or convenient to dissolve the isothiazolone is not generally detrimental to the dilution performance of the microemulsions of the invention so that the invention extends to the presence

I ofsuch optional further ingredient but not to the presenceofLqther unspecified ingredients in such

The isothiazolones which^maybeemployed in this -invention include those having a water solubility of less than 1% by weight of the formula:

wherein Y is an unsubstituted alkyl group of 2 to 18 carbon atoms, a substituted alkyl group of 2 to 18 carbon atoms having at least one hydrogen atom replaced by hydroxy, halo, cyano, alkylamino, dialkylamino, phenylamino, halophenylamino, carboxy, carbalkoxy, alkoxy, aryloxy, morpholino, piperidine, pyrrolidonyl, carbamoxy, or isothiazolonyl, wherein the total number of carbon atoms in the substituted alkyl group does not exceed 18, an unsubstituted or halo-substituted alkenyl group of 4 to 18 carbon atoms, unsubstituted or halo-substituted alkynyl group of 4 to 18 carbon atoms, an unsubstituted or alkyl-substituted cycloalkyl group having a four to six carbon atom ring and up to 12 carbon atoms, an unsubstituted or a halo-, lower alkyl-, or lower alkoxy-substituted aralkyl group wherein the total number of carbon atoms in the aralkyl group does not exceed 10; or an unsubstituted or a halo-, nitro-, lower alkyl-, or lower carbalkoxly-, substituted aryl group wherein the total number of carbon atoms in the 1 aryl group does not exceed 10; and R and R are the same or different substituent selected from hydrogen, halogen, or a alkyl group.

It will be apparent to the skilled person that the water solubility of the isothiazolones depends on the type of substituent (i.e. Η,Η¹ and Y). For example, the carbon content of the alkyl group required for low solubility will vary depending on the R or R¹ or both the R and R^ substituents. For example, when R=R^=halo, the alkyl group can be as low as two carbon atoms for the water solubility to be less than 1%. However when only one of the R or R¹ is halo and the other is hydrogen, the alkyl group will need to contain at least

ו four carbon atoms. When both R and R are hydrogen then the alkyl group will be found to require at least six carbon atoms for low solubility.

In 100 parts by weight (p.b.w.) of the compositions of the invention, these isothiazolones are used in an amount of 0.1 to 50 p.b.w, in combination with 0.1 to 25 p.b.w. of anionic surfactant, 0.1 to 25 p.b.w. of specified cosurfactant, 0.5 to 50 p.b.w. of specified polyoxyethylene/polyoxypropylene block copolymer, 10 to 99 p.b.w. water and 0 to 30 p.b.w. of adjuvant(s).

Anionic surfactants which may be employed include alkylaryl sulfonate salts containing from 6 to 20 carbon atoms in the alkyl group, such as nonyl

ר benzene sulfonate salts, dodecyl benzene sulfonate salts and tridecylbenzene sulfonate salts; salts of (C״ to C_9n alkyl sulfates; salts of (C_1n to C_on) fatty alcohol ethoxylate sulfates containing from 2 to 15 moles of ethylene oxide, such as decyl alcohol sulfate salts [^c1q^h23°^^ch2^CH2^O^2®°3 ], dodecyl EO.^ sulfate salts, and tridecyl EO^ sulfate salts; mono or dialkyl (C₄ to C₁₃) sulfosuccinate salts, such as dioctyl sulfosuccinate salts and ditridecyl sulfosuccinate salts; and sulfated oils such as sulfated castor oil and sulfated neets foot oil.

The counter ion of the sulfonate and sulfate salts described above may be the alkali metal or alkaline earth metal salts such as sodium, potassium, calcium and magnesium; ammonium salts; mono-, di- or tri-alkyl ammonium salts from amines, such as methylamine, dimethylamine and triethylamine; mono-, di- or tri-hydroxyalkylammonium salts from amines such as ethanolamine, diethanolamine and triethanolamine. Especially preferred are the sodium salts.

Suitable cosurfactants include alkyl alcohols such as (C^-C^q) alkyl alcohols and, preferably (Cg to Cg) alcohpls; other suitable cosurfactants include alkyl alkyoxylated alcohols of the formula CHJCH״) (OC״H.) OH or CH,(CH₀) (OC,H״) OH

2 n 24m 3 2 n 36m wherein n is 0 or an integer up to 7 and preferably 3 to 5 and m is an integer of 1 to 4 and preferably 1 to 2.

Important to this invention is the use of one or more polyoxyethylene and polyoxypropylene block copolymers of the formula:

CH_ *

R(-CHCH״O) (CH₉CH0״) H 1 ^Z 1 m n wherein R is (C^-Cg) alkoxy or a radical of the formula HO(CH״CH״O) ¹ - where m¹ is an integer £/ M JI greater than 15 and preferably greater than 20 and η* is an integer greater than 10 and preferably greater than 20;

having a weight average molecular weight above 1750 and preferably above 3000 containing 10 to 80% by weight of ethylene oxide units. The presence of this copolymer enables the dilution of the microemulsion while still retaining the characteristics of a microemulsion.

In addition, it may be necessary in the use of the microemulsions or in the preparation of the microemulsion, to use various adjuvants, for example antifoam agents (such as the commerically available silicone antifoam emulsions) antifreeze agents (such as propylene glycol and urea) water soluble inorganic salts (such as sodium chloride and magnesium sulfate) which are used to optimize the action of the surfactant by increasing the concentration of the surfactant at the interface of the microemulsion.

For ease in preparing microemulsions of crystalline isothiazolones, such as 4,5 dichloro-n-octyl isothiazolone, those isothiazolones may be dissolved in water-immiscible organic solvents such as aromatic and nonaromatic hydrocarbons, esters, amides, kerosene, dioctylphthalate, dimethyl alkyl (C_c-Ct_O) amides or kylene, before combining with other ingredients to make the microemulsion.

The ratios of components are as follows: (All parts by weight.

<td></td><td> General</td><td> Preferred</td><td> Most Preferred</td>

<td> Isothiazolone....</td><td> 0.1-50</td><td> 1-30</td><td> 1-12.5</td>

<td> Anionic Surfactant.,</td><td> 0.1-25</td><td> 1-15</td><td> 1-4</td>

<td> Cosurfactant.... Polyoxye thylene/ polyoxypropylene</td><td> 0.1-25</td><td> 1-20</td><td> 1-6</td>

<td> copolymer......</td><td> 0.5-50</td><td> 1-40</td><td> 1-10</td>

<td> Adjuvants...... Maximum total of</td><td> 0-30</td><td> 0-20</td><td> 0-16</td>

<td> above components</td><td> __90</td><td> __80</td><td> __50</td>

<td> plus water to make a</td><td> total of</td><td> 100 parts</td><td> by weight.</td>

As specifed above, the compositions may additionally contain such amounts of water-miscible solvent as is necessary or convenient to dissolve the isothiazolone.

The ratio of total surfactant to emulsified oil is important. The amount of surfactant required to emulsify an oil will depend on the amount of oil in the emulsion, more specifically the interfacial surface area which is proportional to the amount of emulsified oil at a constant particle size and can be determined in any individual case by simple trial and error. The microemulsions described here have relatively low surfactant to oil ratios, about 1:1. Thus the total surfactant (anionic surfactant and cosurfactant and EO/PO copolymer) required to make a 1% oil emulsion, (1%AI if no solvents are present) is about 1%. Ten percent surfactant would be required to prepare an equivalent 10% Al microemulsion. If the ratio of surfactant to oil increases to deviate significantly from 1:1 (say >5:1) the compositions are better described as solubilized emulsions or micellar solutions. The compositions required to prepare microemulsions are usually very specific while the exact composition requirements to make a micellar solution are less exacting because of the much greater amount of surfactant used.

These biocidal microemulsions are useful in many areas of preservation including disinfectants, sanitizers, cleaners, deodorizers, liquid and powder soaps, skin removers, oil and grease removers, food processing chemicals, dairy chemicals, food preservatives, animal food preservatives, wood preservation, polymer latices, paint, lazures, stains, mildewicides, hospital and medical antiseptics, medical devices, metal working fluids, cooling water, air washers, petroleum production, paper treatment, pulp and paper slurries, paper mill slimicides, petroleum products, adhesives, textiles, pigment slurries, latexes, leather and hide treatments, petroleum fuel, jet fuel, laundry sanitizers, agricultural formulations, inks, mining, nonwoven fabrics, petroleum storage, rubber, sugar processing, tobacco, swimming pools, photographic rinses, cosmetics, toiletries, pharmaceuticals, chemical toilets, household laundry products, diesel fuel additives, waxes and polishes, oil field applications, and many other applications where water and organic materials come in contact under conditions which allow the growth of undesired microorganisms.

It is well known in the art that the performance of biocides is frequently enhanced by combining one or >

more biocides. In fact, there have been numerous examples of synergistic combinations of biocides. Thus, other known biocides may be combined advantageously with the microemulsions of this invention.

When the concentrate microemulsions (0.1-50% Al) are diluted in water, the microemulsion remains. This is due to the presence of the EO/PO block copolymers. While the use of the anionic surfactant and cosurfactant by themselves at the proper level will form a microemulsion in the concentrate, when diluted, macroemulsions form which phase separate, and sometimes quite rapidly. In contrast, the dilutions described here are stable toward phase separation for months.

Microemulsions, especially those containing nonionic surfactants (EO/PO types here) tend to exhibit phase changes when stored hot or cold. These phase changes are undesirable because ultimately layers may separate. The microemulsions of this invention may be formulated to remain microemulsions at anticipated storage temperatures (O°C to 54°C).

The microemulsions of this invention may be formulated to remain microemulsions even when diluted in either soft (e.g. deionized) water or hard (e.g. Army Hard 342 ppm) water.

Examples

In the Examples which follow, which are given for the purposes of illustration only, the following procedures and abbreviations are used. All parts and percentages are by weight unless otherwise specified.

A. Testing Microemulsions (1) The concentrate appearance (a) initial observation at ambient temperature

C = clear appearance microemulsion SO = slightly opalescent microemulsion

O = opalescent microemulsion

CL = cloudy appearance macroemulsion

P = phase separation - layer(s) formed - unstable macroemulsion (b) observation, hot (54’C) and cold (0°C) (same evaluation symbols)

The microemulsion concentrate is prepared and a portion placed in an oven at 54°C and another portion in a refrigerator at 0°C. An observation is made after temperature equilibration (usually about 2 hours).

Another observation is made at a later time (1 to 2 weeks).

(2) Aqueous dilutions

Dilutions are made with 1 part microemulsion and 25 parts water. Initially tap water is used .^s (200 ppm hardness). In later stages a variety of dilutions using water of various hardness levels were evaluated (0, 50, 200, 342 ppm). A rating scale of 0-5 is used to evaluate the clarity of the dilutions. The sample is evaluated immediately after the dilution.

;0 Because there can be a tendency for coalescence of emulsified particles with time to give large particles and a corresponding increase in opacity, a second reading is taken at two hours and in the final

ו _ compositions, at 24 hours. The scale is defined as follows:

= perfectly clear;

= clear, very slight opalescence;

. ׳ = opalescent;

= opalescent, slightly cloudy;

= cloudy (macroemulsion); and = phase separation.

(+ is used to denote a slightly lower reading) 0 (- is used to denote a slightly higher reading)

A rating in the range of 0 to 3 indicate the material is a microemulsion with the rating 3 indicating borderline micro/macro. A rating of 4 indicates a macroemulsion. A rating of 5 indicates ⁵ unstable macroemulsion with a tendency toward phase separation.

Another rating is the ease with which the microemulsion mixed with water. (Self emulsification SE)

VG = spontaneous mixing, little agitation needed

G = some agitation needed

F = substantial agitation needed

I

Example 1 - Illustrates that dilution of microemulsion forms macroemulsion

Microemulsions could be formed at 12.5% Al by using sodium dodecylbenzenesulfonate as the surfactant and butoxyethanol as the cosurfactant with either the

99% technical or 45% propylene glycol solution of technical isothiazolone.

<td colspan="3"> Experiment A</td><td> Experiment B</td>

<td> 10</td><td colspan="2"> n-Octyl-4-isothiazolin-3... 28.0 -one (45%) in propylene glycol¹</td><td> ———</td>

<td></td><td> n-Octyl-4-isothiazolin-3., -one (99%)</td><td></td><td> 12.6</td>

<td></td><td> (as Al)..........</td><td> ... (12.6)</td><td> (12.5)</td>

<td> 15</td><td> Sodium dodecylbenzene sulfonate (60% aq)....</td><td> ... 10.0</td><td> 10.0</td>

<td></td><td> Butoxyethanol.......</td><td> ... 5.0</td><td> 10.0</td>

<td></td><td> Water..........</td><td> ... 57.0</td><td> 67.4</td>

<td></td><td></td><td> 100.0</td><td> 100.0</td>

Concentrate Appearance C C

A 1:25 dilution in water of either Experiment A or

B resulted in a cloudy macroemulsion which separated on standing.

Subsequently referred to as n-octyl isothiazolone

Example 2 - Illustrates use of different cosurfactants wt.%

Evaluation of Cosurfactants

<td></td><td> A</td><td> B</td><td> C</td><td> D</td>

<td> n-Octyl-isothiazolone...</td><td> . 28.0</td><td> 28.0</td><td> 28.0</td><td> 28.0</td>

<td> (45% in propylene glycol)</td><td></td><td></td><td></td><td></td>

<td> Sodium dodecylbenzene</td><td></td><td></td><td></td><td></td>

<td> sulfonate (60% aq)....</td><td> .. 2.5</td><td> 2.5</td><td> 2.5</td><td> 2.5</td>

<td> B^uPO28^EO42^OH.......</td><td> .. 5.0</td><td> 5.0</td><td> 5.0</td><td> 5.0</td>

<td> Butoxyethanol.......</td><td> .. 5.0</td><td> ——</td><td> —</td><td></td>

<td> n-Hexanol.........</td><td> . . —</td><td> 5.0</td><td> —</td><td> —</td>

<td> Hexoxyethanol.......</td><td> .. “</td><td> ——</td><td> 5.0</td><td></td>

<td> Cg־C10 Alcohol mixture..</td><td></td><td></td><td> —</td><td> 5.0</td>

<td> Water...........</td><td> .. _2s.</td><td> qs</td><td> qs</td><td> qs</td>

<td></td><td> 100.0</td><td> 100.0</td><td> 100.0</td><td> 100.0</td>

<td> 'qs = quantity sufficient</td><td> to give</td><td> 100</td><td></td><td></td>

<td> Concentrate</td><td> A</td><td> B</td><td> C</td><td> D</td>

<td></td><td></td><td></td><td></td><td></td>

<td> Initial Appearance Ambient</td><td> c</td><td> CL</td><td> C</td><td> c</td>

<td> Appearance 24 hr., 54°C</td><td> c</td><td> CL</td><td> C</td><td> so</td>

<td> Appearance 24 hr., 0°C</td><td> c</td><td> C</td><td> C</td><td> c</td>

Butoxyethanol and hexoxyethanol are preferred cosurfactants’. A phase change is seen between ambient temperature and 0°C with n-hexanol and between ambient temperature and 54°C with the C₈־C₁₀ alcohol mixture.

Example 3

An experiment to determine the effects of varying three surfactants and the effect of EO/PO on dilution.

wt %

<td> 5</td><td colspan="2"> A</td><td> B</td><td> c</td><td> D</td><td> E</td><td> F</td><td> G</td><td> H</td><td> I</td>

<td></td><td></td><td></td><td></td><td></td><td></td><td></td><td>^{1 1}</td><td></td><td></td><td></td>

<td></td><td colspan="2"> n-Octylisothiazolone 28 (45% in propylene glycol) Sodium dodecylbenzene</td><td> 28</td><td> 28</td><td> 28</td><td> 28</td><td> 28</td><td> 28</td><td> 28</td><td> 28</td>

<td></td><td> sulfonate (40% aq).</td><td> 4</td><td> 6</td><td> 2</td><td> 6</td><td> 2</td><td> 6</td><td> 2</td><td> 6</td><td> 2</td>

<td> 10</td><td> bupo₂₈eo₄₂oh....</td><td> 5</td><td> 7</td><td> 7</td><td> 3</td><td> 3</td><td> 7</td><td> 7</td><td> 3</td><td> 3</td>

<td></td><td> Butoxyethanol....</td><td> 5</td><td> 7</td><td> 7</td><td> 7</td><td> 7</td><td> 3</td><td> 3</td><td> 3</td><td> 3</td>

<td></td><td> Water........ Concentrate</td><td> 5a 100</td><td> 52 100</td><td> 56 100</td><td> 56 100</td><td> 60 100</td><td> 56 100</td><td> 60 100</td><td> 60 100</td><td> 64 100</td>

<td> 15</td><td> Ambient Temperature Appearance</td><td> C</td><td> C</td><td> C</td><td> C</td><td> O</td><td> C</td><td> C</td><td> C</td><td> O</td>

<td></td><td> 54°C Appearance</td><td> SO</td><td> C</td><td> SO</td><td> C</td><td> O</td><td> C</td><td> SO</td><td> C</td><td> 0</td>

<td></td><td> O’C Appearance Dilution (1:25)¹</td><td> c</td><td> C</td><td> c</td><td> C</td><td> CL</td><td> C</td><td> C</td><td> C</td><td> CL</td>

<td> 20</td><td> Self emulsification (SE)</td><td> VG</td><td> VG</td><td> VG</td><td> VG</td><td> VG</td><td> VG</td><td> VG</td><td> G</td><td> VG</td>

<td></td><td> initial appearance</td><td> 2</td><td> 1</td><td> 2</td><td> 2</td><td> 3</td><td> 1</td><td> 2</td><td> 2</td><td> 3</td>

<td></td><td> 2 hr. appearance. ¹ - Dilution 1 part</td><td colspan="3"> 3 2+ 2- of concentrate per</td><td colspan="2"> 3 3 25 parts of</td><td> 2 water</td><td> ־2</td><td> 3</td><td> 3</td>

Conclusions: EO/PO surfactant containing formulations

3A through 31 gave transparent microemulsion dilutions unlike Example 1.

The concentrate is clearer with a high sulfonate level at 54°. At 0° the low sulfonate-low EO/PO surfactant gives a cloudy emulsion. The stabilization of the dilution is increased by high sulfonate and high EO/PO surfactant level. Butoxyethanol has little effect within the range studied.

Example 4 - Evaluation of various hydrophile/-lipophile balance polyoxyethylene/polyoxypropylene block copolymers R(PO)_m(EO)_nH &lt;*3

<td> 5</td><td> HO(CH₂CH₂O)</td><td>_n(CHCH₂O)</td><td colspan="2"> m(CH₂CH₂O)_nH</td><td> BuOPO_mEO_nOH</td>

<td></td><td></td><td> A-E</td><td></td><td></td><td> F</td>

<td></td><td></td><td></td><td></td><td></td><td> Hydoph i1e-L i poph i</td>

<td></td><td> Experiment</td><td> n</td><td> m</td><td> mw</td><td> Balance (HLB)</td>

<td></td><td> A....</td><td> . 38</td><td> 54</td><td> 6500</td><td> 15</td>

<td> 10</td><td> B....</td><td> . 20</td><td> 54</td><td> 4950</td><td> 9</td>

<td></td><td> C....</td><td> . 13</td><td> 30</td><td> 2900</td><td> 15</td>

<td></td><td> D....</td><td> . 21</td><td> 67</td><td> 5750</td><td> 8</td>

<td></td><td> E....</td><td> . 128</td><td> 54</td><td> 14,600</td><td> 27</td>

<td></td><td> F....</td><td> . 29</td><td> 20</td><td> 2,500</td><td> 16</td>

<td> IS</td><td colspan="3"> The following compositions:</td><td> #A“F</td><td></td>

Wt % n-Octylisothiazolone 12.5

Propylene glycol. 15.5

Sodium dodecyl benzene sulfonate (40% aq) 4.0

EO/PO surfactant 6.0

Butoxyethanol 5.0

Water 57.0

100.0

<td> 25</td><td> A</td><td> B</td><td> c</td><td> D</td><td> E</td><td> F</td>

<td></td><td> Concentrate appearance C</td><td> c</td><td> c</td><td> C</td><td> CL</td><td> C</td>

<td></td><td> 1:25 dilution</td><td></td><td></td><td></td><td></td><td></td>

<td></td><td> 2 hr. reading 2־</td><td> 1</td><td> 3</td><td> 1</td><td> 4</td><td> 2</td>

<td></td><td colspan="3"> Conclusion: EO/PO surfactants</td><td> with an</td><td> HLB of</td><td> 8-9</td>

<td> 30</td><td> gave the optimum dilution.</td><td></td><td></td><td></td><td></td><td></td>

¹ HLB is defined Becher, P; Surfactants in Solution, Vol. 3,

Mittal, K.L. and LxndmanT B, Eds., Plenum Press, N.Y. 1984 p.925

Example 5 An experiment was run to optimize the microemulsion containing HOEO21POg₇EO₂1OH surfactant. (These formulations contain a small amount of a 31% silicone emulsion - to eliminate foaming.)

<td rowspan="2"></td><td colspan="4"> wt %</td><td rowspan="2"> E</td><td rowspan="2"> F</td><td rowspan="2"> G</td><td rowspan="2"> H</td><td rowspan="2"> I</td>

<td> A</td><td> B</td><td> C</td><td> D</td>

<td> n-Octylisothiazolone</td><td> 12.50</td><td> 12.50</td><td> 12.50</td><td> 12.50</td><td> 12.50</td><td> 12.50</td><td> 12.50</td><td> 12.50</td><td> 12.50</td>

<td> Propylene glycol</td><td> 15.50</td><td> 15.50</td><td> 15.50</td><td> 15.50</td><td> 15.50</td><td> 15.50</td><td> 15.50</td><td> 15.50</td><td> 15.50</td>

<td colspan="2"> Dodecylbenzene sulfonate (40% aq)6.00</td><td> 6.00</td><td> 4.00</td><td> 4.00</td><td> 6.00</td><td> 6.00</td><td> 4.00</td><td> 4.00</td><td> 5.00</td>

<td> HOEO_n1ΡΟ_εΊΕΟ-,ΟΗ zi 0 / a</td><td> 8.00</td><td> 6.00</td><td> 8.00</td><td> 6.00</td><td> 8.00</td><td> 6.00</td><td> 8.00</td><td> 6.00</td><td> 7.00</td>

<td> Butoxyethanol..</td><td> 6.00</td><td> 6.00</td><td> 6.00</td><td> 6.00</td><td> 4.00</td><td> 4.00</td><td> 4.00</td><td> 4.00</td><td> 5.00</td>

Silicone antifoam

<td> emulsion*..</td><td> .. 0.01</td><td> 0.01</td><td> 0.01</td><td> 0.01</td><td> 0.01</td><td> 0.01</td><td> 0.01</td><td> 0.01</td><td> 0.01</td>

<td> Water....</td><td> ♦. _gs_</td><td> qs</td><td> qs</td><td> qs</td><td> qs</td><td> qs</td><td> qs</td><td> qs</td><td> qs</td>

<td></td><td> 100.00</td><td> 100.00</td><td> 100.00</td><td> 100.00</td><td> 100.00</td><td> 100.00</td><td> 100.00</td><td> 100.00</td><td> 100.00</td>

*31 % aqueous emulsion

־ -

<td> Concentrate</td><td> A</td><td> B</td><td> C</td><td> D</td><td> E</td><td> F</td><td> G</td><td> H</td><td> I</td>

<td> Appearance Ambient Temperature</td><td> C</td><td> C</td><td> C</td><td> C</td><td> c</td><td> C</td><td> C</td><td> C</td><td> c</td>

<td> 2 hr. 54°C.....</td><td> C</td><td> C</td><td> SO</td><td> SO</td><td> C</td><td> C</td><td> SO</td><td> SO</td><td> c</td>

<td> 2 hr. Q°C.....</td><td> C</td><td> C</td><td> C</td><td> C</td><td> c</td><td> c</td><td> c</td><td> c</td><td> c</td>

<td> 1 hr. 70°C.....</td><td> C</td><td> C</td><td> 0</td><td> 0</td><td> c</td><td> c</td><td> SO</td><td> 0</td><td> c</td>

<td> 1 hr. 80’C.....</td><td> C</td><td> C</td><td> 0</td><td> 0</td><td> c</td><td> c</td><td> so</td><td> 0</td><td> c</td>

<td> 1 hr. 90^eC.....</td><td> C</td><td> C</td><td> 0</td><td> 0</td><td> c</td><td> c</td><td> so</td><td> 0</td><td> c</td>

<td> 4 days 54°C....</td><td> C</td><td> C</td><td> SO</td><td> SO</td><td> c</td><td> C</td><td> so</td><td> c</td><td> C</td>

<td> 4 days -10״C....</td><td> C</td><td> C</td><td> c</td><td> C</td><td> c</td><td> c</td><td> c</td><td> C</td><td> c</td>

<td> Dilution 1:25 SE</td><td> VG</td><td> VG</td><td> VG</td><td> VG</td><td> VG</td><td> VG</td><td> VG</td><td> VG</td><td> VG</td>

<td colspan="10"> Appearance</td>

<td> Init. 50 ppm hardness....</td><td> .. 2</td><td> 3</td><td> 1</td><td> 3</td><td> 2</td><td> 3</td><td> 1</td><td> 3</td><td> 3</td>

<td> 2 hr. 50 ppm hardness....</td><td> .. 2</td><td> 4</td><td> 1</td><td> 3</td><td> 2</td><td> 4</td><td> 1</td><td> 3</td><td> 3</td>

<td> Init. 200 ppm hardness....</td><td> .. 0</td><td> 1</td><td> 0</td><td> 1-</td><td> 0</td><td> 1</td><td> 0</td><td> 1</td><td> 0</td>

<td> 2 hr. 200 ppm hardness....</td><td> .. 1</td><td> 1</td><td> 1</td><td> 1</td><td> 1</td><td> 1</td><td> 1</td><td> 1</td><td> 1</td>

<td> Init. 342 ppm hardness....</td><td> .. 1</td><td> 1</td><td> 2</td><td> 2</td><td> 1</td><td> 1</td><td> 2</td><td> 1</td><td> 1</td>

<td> 2 hr. 342 ppm hardness....</td><td> .. 3</td><td> 3</td><td> 3</td><td> 3+</td><td> 3</td><td> 3</td><td> 3</td><td> 3</td><td> 3</td>

<td> The</td><td> dilution</td><td colspan="2"> stability</td><td colspan="2"> of Example</td><td> 5C and</td><td> Example</td><td></td><td></td>

5G was very good (essentially equivalent) with the formulation of Example 5G having a less noticable phase change when heated above 54°C. Cold stability at -10°C is good with all samples.

Example 6 An experiment to compare 2 different methods of preparation of the formulation of Example 5C.

A - Experiment 5C was repeated by mixing all ingredients except n-octyl isothiazolone and heating the mixture to 50^eC with agitation to form a clear solution. n-Octyl isothiazolone was then added at ambient temperature and a clear microemulsion formed upon agitation.

B - Experiment 5C was repeated except solution of the ΗΟΕΟ2^ΡΟβγΕΟ2!ΟΗ in butoxyethanol was not initially added. A macroemulsion formed when all ingredients except this solution were mixed. When this butoxyethanol solution was added to the macroemulsion a clear microemulsion is formed. The properties of these ¹⁵ two microemulsions were evaluated.

6A 6B

Concentrate Initial appearance....... CC

Appearance 3 days 54^eC..... CC

Appearance 3 days 0®C C C

Dilution 1:25

SEVG VG hr. appearance 50 ppm hardness......... 11

2 0 0 ppm hardness........ 00

342 ppm hardness........ 2-2Conclusion - These two methods of preparation afford equivalent microemulsions.

Example 7 - Use of 99% technical n-octylisothiazolone.

Wt %

<td> A</td><td rowspan="2"> B</td><td rowspan="2"> C</td><td rowspan="2"> ם</td><td rowspan="2"> E</td><td rowspan="2"> F</td><td rowspan="2"> G</td><td rowspan="2"> H</td><td rowspan="2"> I</td>

<td></td>

<td> n-Octyl isothiazolone (99%) 12.60</td><td> 12.60</td><td> 12.60</td><td> 12.60</td><td> 12.60</td><td> 12.60</td><td> 12.60</td><td> 12.60</td><td> 12.60</td>

<td> Sodium dodecylbenzene sulfonate (40% aq)5.00</td><td> 5.00</td><td> 5.00</td><td> 5.00</td><td> 3.00</td><td> 3.00</td><td> 3.00</td><td> 3.00</td><td> 4.00</td>

<td> hoeo₂₁po₆₇eo₂₁oh 9.00</td><td> 7.00</td><td> 7.00</td><td> 9.00</td><td> 9.00</td><td> 9.00</td><td> 7.00</td><td> 7.00</td><td> 8.00</td>

<td> Butoxyethanol.. 5.00</td><td> 5.00</td><td> 3.00</td><td> 3.00</td><td> 5.00</td><td> 3.00</td><td> 5.00</td><td> 3.00</td><td> 4.00</td>

<td> Silicone antifoam emulsion.... 0.01</td><td> 0.01</td><td> 0.01</td><td> 0.01</td><td> 0.01</td><td> 0.01</td><td> 0.01</td><td> 0.01</td><td> 0.01</td>

<td> Water...... qs</td><td> qs</td><td> qs</td><td> qs</td><td> qs</td><td> qs</td><td> qs</td><td> qs</td><td> _ qs</td>

<td> 100.00</td><td> 100.00</td><td> 100.00</td><td> 100.00</td><td> 100.00</td><td> 100.00</td><td> 100.00</td><td> 100.00</td><td> 100.00</td>

Concentrate

<td colspan="10"> Appearance</td>

<td> Ambient Temperature</td><td> C</td><td> C</td><td> C</td><td> C</td><td> P</td><td> CL</td><td> CL</td><td> CL</td><td> CL</td>

<td> Appearance 70°C 2 hr.</td><td> C</td><td> C</td><td> C</td><td> c</td><td> P</td><td> P</td><td> P</td><td> P</td><td> P</td>

<td> Appearance 0°C 2 hr.</td><td> C</td><td> c</td><td> C</td><td> c</td><td> CL</td><td> CL</td><td> CL</td><td> CL</td><td> CL</td>

<td> Dilution 1:25 2 hr. reading 0 ppm hardness</td><td> 1</td><td> 0</td><td> 2</td><td> 0</td><td> 0</td><td> 0</td><td> 1</td><td> 1</td><td> 1</td>

<td> 200 ppm hardness</td><td> 2</td><td> 2</td><td> 1</td><td> 1</td><td> 1</td><td> 1-</td><td> 1</td><td> 1-</td><td> 2</td>

Conclusion: A slightly higher sulfonate level gives a clear concentrate which does not phase separate at hot or cold temperature. The preferred formulation using

99% technical is Example 7D because of dilution stability and lack of concentrate phase changes at 0°C and 54°C.

Example 8 Microemulsion of a Solid Isothiazolone

The solid, 4,5-dichloro-n-octyl-isothiazolone, is dissolved in xylene to form the oil to be microemulsified. The following ingredients are mixed together.

Wt %

4,5-dichloro-n-octyl isothiazolone. 10.00

Xylene 5.00

C j. ₂H₂ EO ₂ SO^Na + (6 0 % aq).8.00 hoeo₂₁po₆₇eo₂₁oh 4.00

Butoxyethanol 25.00

Antifoam 0.05

2% aqueous NaCl 47.95

Total 100.00

Appearance concentrateC

Appearance dilution (1:25). 3

Example 9 - Microemulsion of 4,5-Dichloro n-octyl isothiazolone

A solution of solid 4,5 dichloro n-octyl isothiazolone in pentyl alcohol was prepared by mild

S heating. This was added to a mixture of the remaining ingredients and this mixture heated to 50^e°C until a clear microemulsion formed.

Ingredients Parts by Wt.

4,5 Dichloro n-octyl isothiazolone..10.00

Pentyl alcohol 5.00 hoeo₂₁po₆₇eo₂₁oh 8.00 ^12®25^*θ12^θ4^ 60% aqueous)..... 16.00 Butoxyethanol 25.00

Antifoam emulsion 0.05 ¹³ 2% Aqueous NaCl.. 35.95

100.00

Appearance concentrateC

Appearance dilution1

Example 10 - Variation of the cation of dodecylbenzenesulfonic acid.

10% Aqueous dodecylbenzene sulfonic acid was neutralized with potassium hydroxide, ammonium hydroxide, dimethyl amine and diethanol amine. The following formulation was prepared with each of the 4 DBSA solutions.

n-Octyl isothiazolone 28.0 (45% in propylene glycol)

10% DBSA salt solution* 16.0

Butoxyethanol 4.0 hoeo₂₁po₆₇eo₂₁oh 8.0

Water 44.0

100.0

<td rowspan="2"> 15 20</td><td colspan="3"> *(the pH of KOH and NH^OH (HOCH₂CH₂)₂NH solution is</td><td colspan="3"> solution is 7 and the pH of the (CH₃)₂NH and 6)</td>

<td> DBSA Concentrate Appearance Ambient Appearance 0°C Appearance 70°C</td><td colspan="2"> A K⁺ c c c</td><td> B NH₄⁺ Me C C C</td><td> C c c c</td><td> D (HOCH₂CH₂)₂NH₂⁺ c c c</td>

<td> 25</td><td colspan="2"> Dilution 24 hr. appearance 0 ppm 0־</td><td></td><td> 0“</td><td> 1</td><td> 0</td>

<td></td><td> 342 ppm</td><td> 0'</td><td></td><td> 0</td><td> 2</td><td> 0</td>

<td></td><td colspan="2"> Conclusion All of the</td><td> above</td><td> DBSA salts</td><td> are</td><td> effective in</td>

forming microemulsions. Dimethyl amine is least effective of these four.

Example 11 - Latex paints containing isothiazolone microemulsion.

Dried exterior latex paint films are susceptible to disfiguring mildew growth. To prevent this an

<td> isothiazolone microemulsion is added</td><td> to the paint.</td>

<td> A typical exterior latex paint would</td><td> contain: parts by wt.</td>

<td> Natrosol 250 MHR</td><td> 3.0</td>

<td> Ethylene glycol</td><td> 25.0</td>

<td> Water</td><td> 120.0</td>

<td> Tamol® 960</td><td> 7.1</td>

<td> Potassium tripolyphosphate Triton® CF-10</td><td> 1.5 2.5</td>

<td> Colloid 643</td><td> 1.0</td>

<td> Propylene glycol Ti-Pure R902 (titaniumdioxide) Zinc oxide</td><td> 34.0 225.0 25.0</td>

<td> Minex 4</td><td> 147.3</td>

<td> Icecap K Attagel 50</td><td> 50.0 5.0</td>

The above materials are ground for 10-15 minutes

<td> on Cowles Dissolver at 3800-4500 rpm. reduced and the following is added:</td><td> &gt; The speed is</td>

<td> Rhoplex® AC 64 Colloid 643</td><td> 305.9 3.0</td>

<td> Texanol</td><td> 9.3</td>

<td> Microemulsion Example 5C Water</td><td> 7.2 84.8</td>

<td> 2.5% Natrosol 250 MHR</td><td> 118.2 1176.8</td>

A 1176.8 batch represents 100 gallons of paint.

I ־ 26 The inclusion of the isothiazolone will prevent mildew growth on the paint film under conditions where a paint with no biocide will support mildew growth.

Example 12 - Use of Isothiazolone Microemulsion in a water cooling tower.

Evaporative cooling is widely used for dissipation of heat. This is accomplished with a cooling tower in which a large surface area is exposed by running water down a series of slats. Air is moved over the water surface by fans resulting in evaporation. The cooled water is the heat exchange medium. Fungal growth can occur in the water and on the tower surfaces. This growth can cause several operational problems such as fouling, plugging and wood rot, generally leading to loss of cooling efficiency and biodeteriation of the cooling tower itself. To control fungal growth 5-10 ppm active ingredient of the isothiazolone microemulsion prepared in Example 5G can be added directly to the bulk water in the cooling tower weekly.

Example 13 - Using Isothiazolone Microemulsions to prevent fungal growth in metal working fluids.

In the machining of metal parts a metal working fluid is used. This fluid serves to cool, lubricate, 5 and prevent corrosion on the surface being worked. The fluid itself is prepared by adding a metal working concentrate to water. Three gallons Cimcool 5 star 40, a concentrate, is added to 100 gallons of water. This is stored in a sump and pumped to the various machining 1° operations. Spent fluid is returned to the sump for reuse. Over time this fluid can become contaminated with mircoorganism and support fungal growth. This fungal growth can interfere with normal operation by clogging filters in these systems. Addition of 25-50 ₁₅ ppm active ingredient of the isothiazolone microemulsion prepared in Example 4F will control fungal growth.

Example 14 - Use of Isothiazolone Microemulsion as an antisapstain control on wood.

When green lumber is stored in a wet or humid condition, various surface fungal growth can occur 5 which discolors the surface, lowering the value of the lumber. To eliminate this growth an isothiazolone microemulsion is applied to the lumber surface. An aqueous dilution of the microemulsion prepared in Example 4B is prepared at 350 to 1000 ppm of ¹⁰ isothiazolone active ingredient. Freshly sawn timber is dipped in the solution for 30 seconds. The lumber is withdrawn from the solution and allowed to dry. The residual isothiazolone on the wood surface prevents staining due to fungal growth.

Example 15 - Use of Isothiazolone Mier□emulsion as a laundry mildeweide.

A laboratory test was done using the microemulsion defined in Example 5C to determine its effectiveness as a laundry mildeweide. Pieces of fabric were washed in a commercial washing machine and treated with the composition of 5C diluted to the proper concentration in water. The fabric is exposed to the biocide for a 3 minute rinse cycle. The fabric is air dried overnight then sprayed with Sabround Detrose Broth, a nitrogen source for the fungus (A.niger). After air drying the fabric is sprayed with a spore suspension of A.Niger in a 50 ppm solution of surfactant (octyl phenoxy polyethoxy (8) ethanol). Each piece of fabric is hung oh a hook in a chamber in which the relative humidity is maintained at 94% and the temperature at 30°C. After 4 weeks storage the fabric is evaluated for percent fungal coverage.

Growth of A.niger on 100% cotton fabric treated with Isothiazolone Microemulsion 5C.

<td> Concentration of Active</td><td> Percent</td><td> Growth of A.Niger</td>

<td> Ingredient in Fabric</td><td> on 100%</td><td> Cotton Fabric</td>

<td> Treatment Solution ^a</td><td></td><td></td>

<td> (PP™)</td><td> Test 1</td><td> Test 2</td>

<td> 10</td><td> 20</td><td> 10</td>

<td> 20</td><td> 20</td><td> 20</td>

<td> 30</td><td> 20</td><td> 90</td>

<td> 40</td><td> NG^b</td><td> qiC</td>

<td> 50</td><td> NG</td><td> NG</td>

<td> untreated control</td><td> 100</td><td> 100</td>

This mildewcide treatment controlled the fungal growth at 40 ppm active ingredient or above.

a) Concentration of mildewcide based on the dry weight of fabric. Ratio of fabric treatment solution = 1.5.

b) No Growth

c) Trace of Growth