Bleaching and dyeing; fluid treatment and chemical modification – Bleaching – Chemical
Reexamination Certificate
2000-11-14
2002-03-05
Gupta, Yogendra N. (Department: 1751)
Bleaching and dyeing; fluid treatment and chemical modification
Bleaching
Chemical
C008S101000, C008S107000, C252S186100, C252S186390, C510S302000, C510S376000
Reexamination Certificate
active
06352562
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method of cleaning fabrics using laundry detergents and bleaching systems which comprise novel substituted benzoyl caprolactam bleach activators.
BACKGROUND OF THE INVENTION
It has long been known that peroxygen bleaches are effective for stain and/or soil removal from fabrics, but that such bleaches are temperature dependent. At a laundry liquor temperature of 60° C., peroxygen bleaches are only partially effective. As the laundry liquor temperature is lowered below 60° C., peroxygen bleaches become relatively ineffective. As a consequence, there has been a substantial amount of industrial research to develop bleaching systems which contain an activator that renders peroxygen bleaches effective at laundry liquor temperatures below 60° C.
Numerous substances have been disclosed in the art as effective bleach activators. One widely-used bleach activator is tetraacetyl ethylene diamine (TAED). TAED provides effective hydrophilic cleaning especially on beverage stains, but has limited performance on dingy stains and body soils. Another type of activator, such as nonanoyloxybenzenesulfonate (NOBS) and other activators which generally comprise long chain alkyl moieties, is hydrophobic in nature and provides excellent performance on dingy stains. However, many of the hydrophobic activators developed thus far can promote damage to natural rubber parts used in certain washing machines and to natural rubber articles exposed to the activators. Because of these negative effects on natural rubber machine parts and articles, the selection of such detergent-added bleaching systems has been limited.
It has now been determined that in conventional bleaching systems, particularly those comprising a hydrophobic bleach activator and a source of hydrogen peroxide, the bleach activator undergoes perhydrolysis to form a peroxyacid bleaching agent. A by-product of the perhydrolysis reaction between such bleach activators and hydrogen peroxide is a diacylperoxide (DAP) species. It has now further been discovered that the DAP's derived from hydrophobic activators tend to be insoluble, poorly dispersible, oily materials which form a residue which can deposit on the natural rubber machine parts that are exposed to the laundry liquor. The oily DAP residue can form a film on the natural rubber parts and promote free radical and peroxide damage to the rubber, which eventually leads to failure of the part. This is particularly true of rubber parts which have prolonged exposure to the laundry liquor, such as sump hoses.
By the present invention, is has now been discovered that the class of bleach activators derived from substituted benzoyl caprolactams forms peroxyacids upon perhydrolysis without the production of oily, harmful DAP's. Without intending to be limited by theory, it is believed that the bleach activators employed herein provide good cleaning performance with safety to natural rubber, since they do not expose the natural rubber machine parts or articles to DAP oxidation. Whatever the reason, natural rubber parts and articles remain substantially undamaged by the bleaching systems of the present invention.
By the present invention, it has also now been discovered that the substituted benzoyl caprolactam bleach activators of this invention provide both hydrophilic and hydrophobic cleaning, including dingy soil clean-up and enhanced nucleophilic and body soil removal. Furthermore, the bleaching systems and activators herein are effective at low concentration levels and at temperatures below 60° C. which affords less color damage to fabrics than other activators when used in the manner provided by this invention.
Accordingly, the present invention solves the long-standing need for an effective, color-safe, hydrophobic and hydrophilic bleaching system which does not promote damage to natural rubber parts in washing machines or damage to natural rubber articles.
BACKGROUND ART
U.S. Pat. No. 4,545,784, Sanderson, issued Oct. 8, 1985, discloses the adsorption of activators onto sodium perborate monohydrate.
SUMMARY OF THE INVENTION
The present invention relates to a method of cleaning fabrics using substituted benzoyl caprolactam bleach activators in bleaching systems and laundry detergents. The substituted benzoyl caprolactams have the formula:
wherein R
1
, R
2
, R
3
, R
4
, and R
5
contain from 1 to 12 carbon atoms, preferably from 1 to 6 carbon atoms and are members selected from the group consisting of H, halogen, alkyl, alkoxy, alkoxyaryl, alkaryl, alkaryloxy, and members having the structure:
wherein R
6
is selected from the group consisting of H, alkyl, alkaryl, alkoxy, alkoxyaryl, alkaryloxy, and aminoalkyl; X is O, NH, or NR
7
, wherein R
7
is H or a C
1
-C
4
alkyl group; and R
8
is an alkyl, cycloalkyl, or aryl group containing from 3 to 11 carbon atoms; provided that at least one R substituent is not H.
In a preferred embodiment, R
1
, R
2
, R
3
, and R
4
are H and R
5
is selected from the group consisting of methyl, methoxy, ethyl, ethoxy, propyl, propoxy, isopropyl, isopropoxy, butyl, tert-butyl, butoxy, tert-butoxy, pentyl, pentoxy, hexyl, hexoxy, Cl, and NO
3
. In another preferred embodiment, R
1
, R
2
, R
3
are H, and R
4
and R
5
are members selected from the group consisting of methyl, methoxy, and Cl.
The invention also relates to bleaching systems and laundry detergents comprising the bleach activators. Said bleaching system comprises:
a) at least about 0.1%, preferably from about 1% to about 75%, by weight, of a peroxygen bleaching compound capable of yielding hydrogen peroxide in an aqueous solution;
b) at least about 0.1%, preferably from about 0.1% to about 50%, by weight, of one or more substituted benzoyl caprolactam bleach activators having the formula:
wherein R
1
, R
2
, R
3
, R
4
, and R
5
are as defined above.
The peroxygen bleaching compound can be any peroxide source, and is preferably a member selected from the group consisting of sodium perborate monohydrate, sodium perborate tetrahydrate, sodium pyrophosphate peroxyhydrate, urea peroxyhydrate, sodium percarbo- nate, sodium peroxide and mixtures thereof. Highly preferred peroxygen bleaching compounds are selected from the group consisting of sodium perborate monohydrate, sodium perborate tetrahydrate, sodium percarbonate and mixtures thereof. The most highly preferred peroxygen bleaching compound is sodium percarbonate.
The invention also encompasses laundry compositions in granular, paste, liquid, or bar form which comprise the aforesaid bleaching system together with detergent ingredients which are present in the composition at the levels indicated hereinafter.
The substituted benzoyl caprolactam herein can also be used in combination with other bleach activators, such as N-alkyl capro- lactam, unsubstituted benzoyl caprolactam, tetraacetyl ethylene diamine, alkanoxybenzenesulfonate, including nonanoyloxybenzene- sulfonate, benzoxazin-type bleach activators, and peroxyacid agents and activators having amide moieties.
The bleaching method herein is preferably conducted with agitation of the fabrics with an aqueous liquor containing the aforesaid bleaching system at levels from about 50 ppm to about 27,500 ppm. The method can be carried out at any desired washing temperature, even at temperatures below about 60° C., and is readily conducted at temperatures in the range of from about 5° C. to about 45° C. The method can be conducted conveniently using a composition which is in bar form, but can also be conducted using granules, flakes, powders, pastes, and the like.
The aqueous laundry liquor typically comprises at least about 300 ppm of conventional detergent ingredients, as well as at least about 25 ppm of the bleaching compound and at least about 25 ppm of a bleach activator. Preferably, the liquor comprises from about 900 ppm to about 20,000 ppm of conventional detergent ingredients, from about 100 ppm to about 25,000 ppm of the bleaching compound and from about 100 ppm to about 2,500 ppm of the bleach activator. The conventional det
Burns Michael Eugene
Willey Alan David
Cook C. Brant
Gupta Yogendra N.
Hamlin Derrick G
Miller Steven W.
The Procter & Gamble Co.
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