Drug – bio-affecting and body treating compositions – Designated organic active ingredient containing – Having -c- – wherein x is chalcogen – bonded directly to...
Reexamination Certificate
2001-11-27
2003-05-20
Stockton, Laura L. (Department: 1626)
Drug, bio-affecting and body treating compositions
Designated organic active ingredient containing
Having -c-, wherein x is chalcogen, bonded directly to...
C548S213000
Reexamination Certificate
active
06566382
ABSTRACT:
This application claims priority of Korean Patent Application No. 2001-0024988, filed on May 8, 2001, the content of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to isothiazolone-containing compositions and a method for stabilizing them.
2. Description of the Related Art
Isothiazolones are compounds having wide-ranging sterilizing activity against many harmful organisms derived from animals and plants such as bacteria, fungi, algae, etc. Isothiazolones are added to products such as cosmetics and paints to inhibit the growth of harmful microorganisms in these products.
3-Isothiazolones decompose readily in polar organic solvents such as alcohol or water, and lose their biological activity with the lapse of time. Typically, a metal nitrate, such as magnesium nitrate, is added to most commercially available 3-isothiazolone-containing compositions to stabilize the 3-isothiazolones; such isothiazolone-containing compositions typically contain 1 to 20% by weight of isothiazolones and 15 to 25% by weight of the metal nitrate. A method for the prevention of chemical decomposition of 3-isothiazolones by adding a metal nitrite, a metal nitrate, etc., is disclosed in U.S. Pat. No. 3,870,795.
Although using metal nitrates as stabilizers of 3-isothiazolones preserves their sterilizing activity for longer periods of time, traces of precipitates are formed from the decomposition of 3-isothiazolone in solution during storage. The trace amounts of precipitates do not deleteriously impact the biological efficacy of isothiazolones; however, the presence of the precipitates gives an undesirable appearance to products, which is detrimental from a commercial standpoint.
In another method, Japanese Patent Publication No. 02-304005 discloses compositions containing 0.1 to 15% by weight of isothiazolones, 1 to 5000 ppm of copper ion, non-ion surfactant and organic solvents, but no nitrate salts. Japanese Patent Laid-open No. 05-170608 discloses that the use of bromic acid, iodic acid, periodic acid, iodates, and periodates instead of bivalent metal salts with magnesium nitrate as a stabilizer for isothiazolone-containing compositions can also prevent “salt shock” which often occurs when a metal nitrate is added to aqueous dispersions of polymers.
U.S. Pat. No. 5,910,503 discloses that a mixture of 0.5 to 35% by weight of isothiazolone compounds and 2 to 30% by weight of metal nitrate with 0.01 to 35% by weight of bromic acid, iodic acid, periodic acid, or salts thereof inhibits precipitation formed during storage and stabilizes aqueous dispersion of polymers (coagulation of latexes). However, in the method as above-mentioned, the amounts of bromic acid, iodic acid, periodic acid, or salts thereof used for preventing precipitate formation is very large. These large amounts thicken the compositions and, in addition, raise the cost of production of the compositions, making it economically unfeasible to employ these compositions commercially.
SUMMARY OF THE INVENTION
The present invention provides stabilized isothiazolone-containing compositions comprising two different stabilizers that can efficiently suppress precipitate formed by by-products in the compositions and formed upon storage of the compositions.
The present invention also provides a method for stabilizing isothiazolones by suppressing the generation of precipitates in isothiazolone-containing compositions.
To achieve the above objects and others, the present invention provides an isothiazolone-containing composition comprising:
a) a 3-isothiazolone compound having the structure of the formula:
wherein:
R
1
and R
2
are the same or different, and each is hydrogen, a halogen, a C
1
-C
4
alkyl group, or an aryl group in which R
1
and R
2
are cyclized, and
R
3
is hydrogen, a C
1
-C
18
alkyl group, a C
2
-C
18
alkenyl group, a C
2
-C
18
alkynyl group, a C
3
-C
12
cycloalkyl group having a ring of 3-8 angles, a C
10
-C
24
aralkyl group, or a C
10
-C
24
aryl group;
b) a metal nitrate;
c) magnesium chloride;
d) at least one of the iodine-containing compounds selected from the group consisting of iodic acid, periodic acid, an iodate salt and a periodate salt;
e) a chlorite salt; and
f) a solvent.
The present invention also provides a method for stabilizing isothiazolones comprising the steps of:
I) adding to a solvent
a) 0.1 to 20% by weight of an 3-isothiazolone compound of the formula:
wherein:
R
1
and R
2
are the same or different, and each is hydrogen, a halogen, a C
1
-C
4
alkyl group, or an aryl group in which R
1
and R
2
are cyclized, and
R
3
is hydrogen, a C
1
-C
18
alkyl group, a C
2
-C
18
alkenyl group, a C
2
-C
18
alkynyl group, a C
3
-C
12
cycloalkyl group having a ring of 3-8 angles, a C
10
-C
24
aralkyl group, or a C
10
-C
10
-C
24
aryl group;
(b) 0.1 to 25% by weight of a metal nitrate; and
(c) 0.1 to 9.0% by weight of a magnesium chloride to form a solution; and
II) mixing
(d) 0.0001 to 0.01% by weight of at least one of the iodine-containing compounds selected from the group consisting of iodic acid, periodic acid, an iodate salt; and a periodate salt with
(e) 0.0001 to 10% by weight of a chlorite salts to form a mixture; and
III) combining the mixture of II) with the solution of I).
The present invention further provides a method of suppressing the growth of microorganisms comprising introducing a 3-isothiazolone-containing composition as described above into the habitat of microorganisms.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The mixing of the two types of compounds, i.e., the iodine-containing compounds and the chlorite salts defined above, each having different reaction mechanisms, with magnesium chloride in specified concentrations, inhibits or prevents precipitate formation in compositions containing isothiazolones. By using concentrations even lower than those previously disclosed, the precipitation of by-products generated in the production of the compositions and minute precipitates formed by the compounds generated during storage can be significantly reduced or prevented, thereby effectively stabilizing the isothiazolone.
According to the present invention, preferred examples of the isothiazolone compounds of Formula 1 are 5-chloro-2-methyl-4-isothiazoline-3-one; 2-methyl-4-isothiazoline-3-one, 4,5-dichloro-2-methyl-4-isothiazoline-3-one; 5-chloro-2-n-octyl-3-isothiazolone; 4,5-dichloro-2-n-octyl-3-isothiazolone and benzisothiazolone. Alternatively, a mixture of these compounds may be used, preferably, of 5-chloro-2-methyl-4-isothiazoline-3-one and 2-methyl-4-isothiazoline-3-one, wherein the weight ratio is preferably from 1:20 to 20:1.
In the isothiazolone-containing compositions of the present invention, the isothiazolones of Formula I are used in an amount that is typically used in isothiazolone-containing solutions, namely, from 0.1 to 20% by weight of the isothiazolone.
To reduce or inhibit the degradation of isothiazolones, the composition of the present invention comprises from 0.1 to 25% by weight of metal nitrate. Preferred metal nitrates include lithium nitrate, potassium nitrate, magnesium nitrate, calcium nitrate, and ammonium nitrate. Most preferred is magnesium nitrate.
Furthermore, the composition of the present invention preferably includes from 0.1 to 9% by weight of magnesium chloride to suppress the formation of the isothiazolone precipitate. Magnesium chloride in an amount of less than 0.1 wt % may not effectively inhibit precipitation; when present in an amount of more than 9 wt %, it may itself precipitate due to its limited solubility.
The composition of the present invention further includes at least one of the iodine-containing compounds defined above in an amount of from about 0.0001 to 0.01 wt %, preferably from 0.001 to 0.005 wt %. If less than 0.0001 wt % is used, precipitation may not be effectively inhibited; an amount above 0.01 wt % is not preferred in commercial applications since it increases the cost without any attendant benefit.
The composition of the invention preferab
Choi Ki Seung
Ha Jae Min
Hahn Soon Jong
Hong Wan Pyo
Jung Hi Weon
Lonza Inc.
Stockton Laura L.
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