Synergistic microbiocidal compositions containing a mixture of a bicyclicpolyoxymethyleneoxazolidine and a 4-isothiazolin-3-one

A synergistic microbiocidal composition comprising as Component (1) a 4-isothiazolin-3-one and as Component (2) a bicyclic polyoxymethyleneoxazolidine of the formula: ##STR1## in which each R represents hydrogen, an alkyl of 1-6 carbons, phenyl, halophenyl or --(CH.sub.2 O).sub.m CH.sub.2 OH in which m is 0-2 and n is 0-4; Component 1/Component 2 being in a weight ratio of at least 1:1.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to inhibiting the growth of bacteria in 
various industrial environments. More particularly, the present invention 
relates to an improved microbiocidal composition and its method of use. 
Still more particularly, the present invention relates to a synergistic 
microbiocidal composition, and its method of use, the composition 
comprising a combination of a 4-isothiazolin-3-one and a bicyclic 
polyoxymethylene oxazolidine. 
2. Description of the Prior Art 
The presence of organic materials in the manufacture and/or use of various 
aqueous systems such as latices, adhesives, paints, coatings, mineral 
slurries and the like renders them susceptible to deterioration by virtue 
of exposure to bacteria and other microorganisms existing in the 
particular environment. It is, therefore, a conventional practice to seek 
to inhibit the microbial deterioration of such systems by incorporating 
therein any of various materials or combinations of materials that are 
characterized by having antibacterial activity. 
Numerous materials have been found to possess such antibacterial activity 
among which are various polyoxymethyleneoxazolidines as disclosed in U.S. 
Pat. No. 4,135,945 and various 4-isothazoline-3-ones as disclosed in U.S. 
Pat. Nos. 4,174,643 and 3,929,561. In addition, U.S. Pat. Nos. 4,173,643, 
3,231,509 and 3,929,561 disclose, respectively, synergistic combinations 
of quaternary ammonium salts with 4-isothiazolin-3-ones; quaternary 
ammonium salts with bis(halomethyl)sufones; and 4-isothiazolin-3-ones with 
bis(halomethyl)sulfones. 
SUMMARY OF THE INVENTION 
It is a principal object of this invention to provide an improved 
microbiocidal composition. It is a further object of this invention to 
provide an improved microbiocidal composition that is storage stable, and 
which is compatible with a variety of systems susceptible to biocidal 
degeneration thereby permitting its use without objectionable and/or 
unacceptable by-product odor, discoloration, thickening and the like. A 
further object of this invention is to provide an improved microbiocidal 
composition that is cost effective, i.e., performs effectively on the 
basis of its cost per unit weight and duration of its effectiveness on the 
treated system. Another object of this invention is to provide an improved 
method of inhibiting bacterial growth in a variety of systems used in 
industry and commerce. 
DESCRIPTION OF THE PREFERRED EMBODIMENT 
These various objects have been met in accordance with the present 
invention by a composition comprising (1) a 4-isothiazolin-3-one in 
combination with (2) a bicyclic polyoxymethyleneoxazolidine. 
In accordance with the present invention, Component (1) of the composition, 
comprises a mixture of: 
(a) 75% 5-chloro-2-methyl-4-isothiazolin-3-one, and 
(b) 25% 2-methyl-4-isothiazolin-3-one 
Component (2) of the composition of the present invention is represented by 
the formula: 
##STR2## 
in which each R represents H, and alkyl of 1-6 carbons, phenyl, halophenyl 
or --(CH.sub.2 O).sub.m CH.sub.2 OH in which m is 0-2 and n is 1-4. 
The preferred bicyclic polyoxymethyleneoxazolidine for use in the 
composition of this invention comprises a mixture of: 
(c) 35% 5-hydroxymethyl-1-aza-3,7-dioxabicyclo(3.3.0)-octane, 
(d) 49% 5-hydroxymethoxymethyl-1-aza-3,7-dioxabicyclo(3.3.0) octane, and 
(e) 16% 5-hydroxymethylpoly[oxymethylene(C.sub.2 : 74%; C.sub.3 : 21%; 
C.sub.4 : 4%, C.sub.5 : 1%)]-1-aza-3,7-dioxabicyclo(3.3.0) octane. 
In the practice of the invention, the composition may be used in a broad 
ratio of Component 1 to Component 2 ranging from about 1:50 to 50:1 parts 
by weight. Because of the cost factor, however, Component 2 will normally 
be used in excess, preferably in a ratio of 1:10 to 1:20 by weight. The 
composition can be employed in the form of a dilute aqueous or non-aqueous 
solution and can be added to the aqueous system to be treated in any 
conventional way in an amount effective to inhibit microorganism growth. 
Generally, the effective concentration will range from as little as 100 
ppm to as much as 5000 ppm depending upon the nature of the system being 
treated. Usually, a concentration on the order of 500-2000 ppm will be 
found adequate.

In order to demonstrate the synergistic microbiocidal activity of the 
composition of this invention, the following example was conducted. All 
parts are by weight unless otherwise noted. 
EXAMPLE 
An unpreserved sample of styrene-butadiene-vinylidene chloride (SBVC) latex 
was analyzed for microbial content before being utilized for preservation 
evaluation according to the invention. It was determined that the latex 
sample was free of contamination. 
The uncontaminated, unprotected SBVC latex was divided into 50 gr. aliquots 
and dosed with the microbiocide composition of this invention as reported 
in the following Table. Each of Components 1 and 2 was also separately 
tested as microbiocides while two aliquots remained untreated to serve as 
controls. 
The challenged inoculum was a pooled suspension of microorganisms 
comprising the bacteria species Pseudomonas, Bacillus and Penicillium, 
that had been grown from contaminated latex material. All of the samples 
were challenged on a weekly basis for 4 weeks with 0.10 ml. of the pooled 
suspension containing at least 10.sup.6 organisms per ml. Following 72 
hours of room temperature incubation, a 1 ml. quantity of each sample was 
transferred to 20 ml. of tryptic soy broth (TSB). The TSB tubes were 
incubated at room temperature for 24 hours and streaked onto TGE plates 
for growth bacteria. After 48 hours incubation at room temperature, the 
plates were read and graded according to the description in the Table. 
The tested composition was the preferred composition referred to above in 
which Component 1 comprised elements (a) and (b) and Component 2 comprised 
elements (c), (d) and (e). Component (1) was obtained from Drew Chemical 
Corporation under the trademark Amerstat.RTM. 251 as an aqueous solution 
containing 1.5% active ingredient. Component (2) was obtained from Nuodex, 
Inc. under the trademark Nuosept.RTM. 95 as an aqueous solution containing 
50% active ingredient. The composition of this invention was adjusted to 
an active ingredient content of 10% for testing. Component (1) was 
individually tested at its commercially available active ingredient 
content of 1.5% while Component (2) was individually tested at 20% total 
active ingredient. Results appear in the following Table. 
TABLE 
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Weekly Growth Rate* 
Biocide Ratio PPM 1 2 3 4 
______________________________________ 
Components 
1:10 500 -- -- -- -- 
1 and 2 1000 -- -- -- -- 
2000 -- -- -- -- 
Components 
1:15 500 -- -- -- -- 
1 and 2 1000 -- -- -- -- 
2000 -- -- -- -- 
Components 
1:20 500 -- -- -- -- 
1 and 2 1000 -- -- -- -- 
2000 -- -- -- -- 
Component 1 500 +3 +3 +3 +3 
1000 +2 +2 +2 +3 
2000 -- +1 +2 +2 
Component 2 500 +1 +1 +1 +2 
1000 -- +1 +1 +2 
2000 -- +1 +1 +1 
Control #1 +2 +4 +4 +4 
Control #2 +4 +4 +4 +4 
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*The rating system for microbial growth on streaked, pre- 
poured agar plates is as follows: 
Growth rate 
Description 
-- No growth; zero colonies 
+1 Maximum of 15 total colonies with 
no more than 5 of these having 
diameters of 1/8 inch 
+2 Sporadic growth on 1/2 total 
streaked area, remaining 1/2 area 
relatively clear; maximum of 20 
total colonies with no more than 
6 of these having diameters 
greater than 1/8 inch 
+3 Dense growth on 2/3-3/4 of 
streaked area; minor colonies too 
numerous to count; 20 or more 
major colonies having diameters 
of 1/8 inch or larger 
+4 Uniform, dense growth over entire 
streaked area; colonies pinhead 
size or larger 
Reference in the disclosure to details of specific embodiments is not 
intended to restrict the scope of the appended claims, which themselves 
recite those features regarded as essential to the invention.