Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – With halogen – nitrogen – oxygen – or phosphorus containing...
Reexamination Certificate
2001-01-30
2002-08-06
Chang, Ceila (Department: 1626)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
With halogen, nitrogen, oxygen, or phosphorus containing...
C548S320500
Reexamination Certificate
active
06429181
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the use of partially halogenated hydantoins to reduce slime in a circulating water slurry containing organic matter and one or more performance additives, such as optical brighteners, while minimizing decomposition of the performance additives.
BACKGROUND OF THE INVENTION
Sodium hypochlorite, chlorine gas, and fully halogenated hydantoins, such as dihalogenated dialkyl hydantoins, are known circulating water slimicides. In paper processing, these slimicides often cause decomposition of expensive performance additives, such as optical brighteners. This results in decreased product quality and process efficiency and increased costs. For example, decomposition of an optical brightener will result in a reduction in the brightening of the paper.
Brightness is a critical control parameter in paper production. Chemicals which interact with optical brighteners cause fluctuations in the brightness of paper produced. In order to control these fluctuations, increased monitoring and process adjustment is required, resulting in increased personnel and equipment costs. Therefore, it is desirable to use slimicides which do not, or minimally, interact with optical brighteners.
Furthermore, the interaction between the slimicide and other performance additives, such as sizing, dyes, wet strength additives, dry strength additives, retention aids, and drainage aids, often results in degeneration of one or both of the slimicide and the performance additives. Thus, it is desirable to use slimicides which do not, or minimally, degrade performance additives while maintaining slimicidal activity.
Fully halogenated hydantoins have previously been used as slimicides in papermaking and textile applications. See, e.g., U.S. Pat. Nos. 4,235,599; 4,297,224; 4,427,692; 4,560,766; 4,654,424; 5,565,576; 5,603,941; and 5,750,061.
U.S. Pat. No. 3,328,294 discloses the use of a N-chlorosulfamate solution prepared by reacting sulfamic acid with a hypochlorite solution for disinfecting paper-processing streams. Enhanced biocidal efficacy is demonstrated over a non-oxidizing biocide containing N-methyldithiocarbamate and cyanodithioimidocarbonate. Unfortunately, as a practical matter, N-chlorosulfamic acid is less effective as a biocide than hypochlorites, thus limiting its desirability as a papermaking slimicide.
U.S. Pat. No. 3,749,672 discloses the use of N-hydrogen materials to formulate bleaching solutions with enhanced stability against spontaneous decomposition. The formulation contains (A) a hypohalite, (B) an N-hydrogen compound, (C) the corresponding N-halo reaction product of (A) with (B), and (D) a buffer to maintain the pH of the formulation between 4 and 11. The N-halo reaction product is present in the formulation at a concentration of 1.0×10
−3
to 1.0 molar.
U.S. Pat. No. 4,382,799 discloses the use of organo-N-chloro compounds, such as an N-chlorinated-5,5-dialkyl hydantoin, and organo-N-bromo compounds for bleaching textiles.
U.S. Pat. No. 4,537,697 discloses aqueous solutions containing a fully halogenated hydantoin and a solubilizing agent, such as magnesium oxide, barium hydroxide, sodium bicarbonate, sodium carbonate, and 5,5-dialkylsubstituted hydantoins.
U.S. Pat. No. 5,565,109 discloses specific N-hydrogen compounds, such as 5,5-dimethylhydantoin, which improve the bactericidal efficacy of hypochlorite solutions, such as sodium hypochlorite in pulp slurries. This reduces the amount of hypochlorite required to achieve biological control. Minimization of chlorine usage reduces the predisposition for adsorbable organic halogen formation.
Japanese Patent No. 08176996 discloses hydantoin slimicides, such as 1-bromo-3-chloro-5,5-dimethyl hydantoin, dibromodiethyl hydantoin, 1,3-dibromo-5,5-dimethyl hydantoin, and 1,3-dichloro-5,5-dimethyl hydantoin, which are effective at a pH of 4 to 8. These dihalohydantoin compounds, however, have been found to significantly degrade and reduce the efficacy of performance additives used in papermaking.
Japanese Patent Application No. Sho 56[1981]-31492 discloses the use of hydantoins to stabilize chlorine solutions.
There is a need for compositions that exhibit enhanced slimicidal efficacy and do not, or minimally, degrade performance additives, such as optical brighteners.
SUMMARY OF THE INVENTION
The inventors have discovered that partially halogenated hydantoins exhibit superior antimicrobial efficacy and decreased performance additive decomposition rates than fully halogenated hydantoins, such as dichlorodimethyl hydantoin (DCDMH). Partially halogenated hydantoins are solutions containing monochlorohydantoin and, optionally, dihalogenated hydantoin or non-halogenated hydantoin.
The present invention is a method of reducing slime in a circulating water slurry comprising organic matter and one or more performance additives, such as optical brighteners, while minimizing decomposition of the performance additives. The method comprises adding one or more partially halogenated hydantoins, such as C
1.1
-chlorodimethyl hydantoin, to the slurry. The concentration of partially halogenated hydantoin maintained in the slurry generally ranges from about 0.01 to about 50 ppm (expressed as Cl
2
). This method is particularly useful for circulating water slurries in paper processing.
DETAILED DESCRIPTION OF THE INVENTION
The inventors have discovered that in circulating water slurries containing a performance additive, partially halogenated hydantoins provide superior microbiocidal efficacy per mole of halogen consumed by the performance additive compared to their fully halogenated analogs.
The term “partially halogenated hydantoin” is defined herein as a solution, which may be a liquid, such as an aqueous slurry, or solid, containing halogenated hydantoins and, optionally, non-halogenated hydantoins having a degree of halogenation greater than 0 but less than 2. The degree of halogenation is the average number of halogen atoms associated with each hydantoin molecule in the solution. Generally, a halogenated hydantoin having a degree of halogenation of 0<x<1 is a mixture of (non-halogenated) hydantoin and monohalo hydantoin at a molar ratio of 1-x:x. A halogenated hydantoin having a degree of halogenation of 1<x<2 is generally a mixture of monohalo hydantoin and dihalo hydantoin at a molar ratio of 2-x:x-1. For example, a solution having an average of 1.5 chlorine atoms associated with each hydantoin molecule, i.e., Cl
1.5
hydantoin, has a degree of halogenation of 1.5. A solution containing Cl
1.5
hydantoin is a mixture of monochloro hydantoin and dichloro hydantoin at a molar ratio of 1:1. Another example of a partially halogenated hydantoin is Cl
0.9
hydantoin, which is a mixture of hydantoin and monochloro hydantoin at a molar ratio of 0.1:0.9. The term “solution” as used herein includes, but is not limited to, solids, liquids, and gases.
The partially halogenated hydantoin may be an X
(2−n)
dialkyl hydantoin, where X is chlorine, bromine, iodine, or a combination thereof and 0<n<2. According to a preferred embodiment, n ranges from about 0.5 to about 1.5. According to another preferred embodiment, n ranges from about 0.8 to about 1.2. According to yet another preferred embodiment, n is greater than 0.2 but less than 1. According to yet another preferred embodiment, n is greater than 0.75 but less than 0.95. According to yet another preferred embodiment, n is greater than 1 but less than 2. According to yet another preferred embodiment, n is greater than 1.05 but less than 1.4, 1.2, or 1.1. According to yet another preferred embodiment, n is about 0.9 or 1.1. According to yet another embodiment, n is about 1.
The alkyl moieties of the partially halogenated hydantoin may be the same or different. A suitable hydantoin has the formula
where X
1
and X
2
are independently hydrogen or halogen and R
1
and R
2
are independently linear or branched C
1
-C
10
alkyl. R
1
and R
2
may be the same or different. R
1
and R
2
are preferably a C
1
-C
4
alkyl.
The partial
Lemke Daniel Wayne
Ludensky Michael Leonid
Sweeny Philip Gerdon
Chang Ceila
Darby & Darby
Lonza Inc.
Small Andrea D.
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