Stable aqueous dispersions of biocides
An aqueous dispersion containing BIT and IPBC prepared using nonionic and anionic surfactants exhibits both chemical and physical stability and is suitable for use as a single product which is capable of imparting to a coating composition a high level of resistance against attack by a broad spectrum of organisms, including bacteria, fungi and algae, in both the wet-state and dry film-state.
1. A composition useful for providing resistance to microbiological attack in both a wet state and a dry film state in a single dose, wherein the composition is comprised of:
a) water;
b) 1% to 12% by weight 1,2-benzisothiazolin-3-one (BIT);
c) 2% to 50% by weight 3-iodo-2-propynyl butyl carbamate (IPBC);
d) a nonionic surfactant which includes an ethoxylated tristyrylphenol containing about 16 moles of ethylene oxide per mole of phenol;
e) an anionic surfactant which includes an alkylbenzene sulfonate; and
f) at least one thickener/suspending agent, in an amount effective to provide the composition with a viscosity of at least 300 centipoise at 25 degrees C.;
wherein BIT and IPBC are present in amounts effective to provide a weight ratio of BIT to IPBC in the range of 0.02 to 2; and
wherein d) and e) are present in an amount effective to provide the composition in the form of a stable aqueous dispersion.
2. The composition of claim 1 , in which the alkylbenzene sulfonate is dodecylbenzene sulfonate.
3. The composition of claim 1 in which the non-ionic surfactant additionally includes a first alkoxylated aliphatic mono-alcohol and a second alkoxylated aliphatic mono-alcohol, each having an aliphatic mono-alcohol segment and an alkoxylated segment, wherein the second alkoxylated aliphatic mono-alcohol differs from the first alkoxylated aliphatic mono-alcohol with respect to at least one of a) chain length of the aliphatic mono-alcohol segment, b) composition of the alkoxylated segment, or c) number of oxyalkylene units in the alkoxylated segment.
4. The composition of claim 3 , in which the first alkoxylated aliphatic mono-alcohol is an ethoxylated C10-C18 aliphatic alcohol containing an average of about 6 to about 15 ethylene oxide units per molecule and the second alkoxylated aliphatic mono-alcohol is an alkoxylated C2-C8 aliphatic alcohol containing both ethylene oxide and propylene oxide units.
5. The composition of claim 4 , in which the first alkoxylated aliphatic mono-alcohol is an ethoxylated C12-C16 linear aliphatic alcohol containing an average of about 8 to about 12 ethylene oxide units per molecule.
6. The composition of claim 4 , in which the second alkoxylated aliphatic mono-alcohol is an alkoxylated n-butanol containing both ethylene oxide and propylene oxide units and having a block copolymer structure.
7. The composition of claim 1 , in which the at least one thickener/suspending agent includes a thickener/suspending agent selected from the group consisting of silicates, polyacrylates, polysaccharides and clays.
8. The composition of claim 1 , in which the weight ratio of BIT:IPBC is in the range of 0.5 to 1.8.
9. The composition of claim 1 , which includes a biocide selected from the group consisting of methylbenzimadazole-2-yl carbamate and 3-(3,4-dichlorophenyl)-1,1-dimethylurea and mixtures thereof.
10. The composition of claim 1 , which includes about 40 to about 60 weight % water.
11. The composition of claim 1 , in which the nonionic surfactant and the anionic surfactant are present in a weight ratio of nonionic surfactant to anionic surfactant in the range of about 1.5:1 to about 8:1.
12. The composition of claim 1 , in which biocides, including BIT and IPBC, and the nonionic surfactant and the anionic surfactant are present in a weight ratio of (biocides):(nonionic surfactant+anionic surfactant) in the range of about 6:1 to about 20:1.
13. A coating composition which is resistant to microbiological attack in both a wet state and a dry film state, comprising a composition in accordance with claim 1 and at least one additional coating ingredient.
14. A method of making a coating composition, comprising combining one or more coating ingredients with an amount of the composition of claim 1 to obtain a coating composition which is resistant to microbiological attack in both a wet state and a dry film state.
15. A composition useful for providing resistance to microbiological attack in both a wet state and a dry film state in a single dose, wherein the composition is in the form of a stable aqueous dispersion and comprises:
a) 45 to 60% by weight water;
b) 3 to 9% by weight 1,2-benzisothiazolin-3-one (BIT); and
c) 2 to 7% by weight 3-iodo-2-propynyl butyl carbamate (IPBC), wherein BIT and IPBC are present in amounts effective to provide a weight ratio of BIT:IPBC in the range of 0.5 to 1.8;
d) 5 to 20% by weight methylbenzimidazole-2-yl carbamate (BCM) or 3-(3,4-dichlorophenyl)-1,1-dimethylurea;
e) 0.5 to 3% by weight at least two alkoxylated aliphatic mono-alcohols, including a first alkoxylated aliphatic mono-alcohol which is an ethoxylated C10-C18 aliphatic alcohol containing an average of about 6 to about 15 ethylene oxide units per molecule and a second alkoxylated aliphatic mono-alcohol which is an alkoxylated C2-C8 aliphatic alcohol containing both ethylene oxide and propylene oxide units;
f) 0.2 to 1% by weight dodecylbenzene sulfonate surfactant; and
g) at least one thickener/suspending agent, in an amount effective to provide the composition with a viscosity of at least 300 cps at 25 degrees C.; wherein the percentages by weight are based on the total weight of a) through g).