Detergent composition and laundry washing method

Details Detergent composition and laundry washing method Detergent composition and laundry washing method

2000-07-13

2001-08-21

Delcotto, Gregory (Department: 1751)

Bleaching and dyeing; fluid treatment and chemical modification

Cleaning or laundering

C510S277000, C510S283000, C510S306000, C510S310000, C510S313000, C510S370000, C510S374000, C510S376000

Reexamination Certificate

active

06277153

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to cleaning compositions and their use in laundry washing machines, especially in industrial Washer Extractors (WE) or Continuous Batch Washers (CBW) having multiple prewashing, washing and rinsing zones or steps.
BACKGROUND OF THE INVENTION
A wash process in a conventional Washer Extractor consists of several steps, including one or more prewash, wash and rinse steps. These steps are carried our consecutively.
A conventional CBW consists of separate prewash, wash and rinse zones. Fresh water is introduced into the rinse zone of the machine and is passed cascade-fashion toward the mainwash zone while the laundry is transported in a countercurrent direction. These steps are carried out sequentially while the wash load is transported.
The detergent compositions used in such machines generally comprise products such as a prewash product, a main wash product, a bleach product and a neutralising product. Also one or more additional products, boosters, could be added to the process to enhance the detergency.
Typical product ingredients are surfactants, sequestering agents, such as phosphates, alkalinity salts, and bleaching agents.
Usually applied bleaching agents are hypochlorite, hydrogen peroxide and peracetic acid.
Contact time of the cleaning composition with the laundry in CBW's is typically quite short, e.g. about 1 to 2 minutes per wash segment.
The cleaned laundry is generally rinsed in a final rinse.
A problem observed when using the above-mentioned generally applied bleaching ingredients is the resulting considerable textile damage, occurring after multiple washings.
The main reason is considered to be the aggressive conditions in the wash for the textile. Both the wash temperatures (of generally 70-90° C.) and the pH are high and the bleaching agents aggressive. These conditions are necessary to obtain adequate cleaning performance and hygiene.
Besides the negative impact on the textile, there are also other negatives associated with the high temperatures applied in the known CBW's of the prior art:
the wash processes require a high amount of energy.
washing polyester cotton textile requires a specific and additional step to the wash process, called cool-down, to prevent creasing of the textile. Over a specific period of time colder water needs to be added to the wash to slowly cool the temperature to below 50° C. This additionally increases wash times and requires more water.
The aggressive products used are difficult to rinse out and high amounts of water in the rinse are required to eliminate these products from the textile.
Not all articles can withstand these high temperatures. In particular, colour damage may easily occur.
Effluant temperatures are high which is often not tolerated by authorities for environmental reasons. Authorities insist more and more on low temperatures of the effluent before it may enter any sewage system.
We have now surprisingly found that these and other problems can be overcome, when applying a cleaning system having (in addition to a main wash product and a neutraliser) at least two separate components, a first component comprising a proteolytic enzyme and a second component comprising an imidoperoxycarboxylic acid bleach ingredient according to the present invention, wherein the first component is introduced into a prewash zone or step, and the second component is introduced into a main wash zone or step. These components are effectively used together with a main wash product and a neutraliser. An optional booster could also be added.
DEFINITION OF THE INVENTION
Consequently, according to a first aspect the present invention provides a chemical cleaning system for a multi tank or a single-tank laundry washing machine having at least 2 separate components for aqueous dissolution or dilution to respective use concentrations, a first component comprising a proteolytic enzyme, and a second component comprising an imido-peroxycarboxylic acid having the formula (I):
wherein
X is H, a halogen or a carboxyl group in any position on the aromatic ring;
R is a straight or branched chain lower alkylene having 1-4 carbon atoms; and
n is an integer in the range from 1-12,
wherein the first component is introduced into a prewash zone or step, and the second component is introduced into a main wash zone or step.
A highly effective method of laundrywashing in a multi-tank (CBW) or single-tank (WE) industrial laundry washing machine is also described, said method comprising the steps of:
(i) formulating at least two separate components of a chemical cleaning system for aqueous dissolution or dilution to respective use concentrations, a first component comprising a proteolytic enzyme, and a second component comprising an imidoperoxycarboxylic acid of formula (I) (as defined in claim
1
);
(ii) introducing the first component into a prewash zone or step, to clean dirty laundry;
(iii) introducing the second component into a main wash zone or step, to effectively complete the cleaning of the laundry.
DETAILED DESCRIPTION OF THE INVENTION
When using the system of the present invention, it was found that effective cleaning performance could be obtained even when applying relatively low temperatures in the wash sections or steps. These temperatures are preferably in the range of from 30-70° C., more preferably 45-55° C., whereas main wash temperatures applied when using the cleaning systems of the prior art are in the range of approximately 70-90° C.
Furthermore, relatively moderate pH conditions , i.e. pH-values in the range of 7-10, preferably 8.5-9.5, are effectively applied in the main wash sections or steps when using the system of the present invention.
It was found that in spite of these moderate conditions, favourable results in respect of detergency, cleaning and bleaching of the treated laundry could still be obtained.
As a result, much less energy was needed and the temperature of the effluent was much lower as compared with the known cleaning system of the prior art, while similar cleaning, detergency, disinfection and bleaching performance was obtained.
Furthermore, a surprising reduction in textile damage was found as compared to the damage observed when applying said known cleaning systems.
In addition, cool-down steps for polyester cotton textiles could be eliminated generating advantages for processing time and reduction in water.
Enzymatic Component
The proteolytic enzymes usable in the system of the present invention are, for example, the subtilisins which are obtained from particular strains of B. subtilis and B. licheniformis, such as the commercially available subtilisins Maxatase, supplied by Gist-Bracades N.V., Delft, Holland, and alcalase, supplied by NOVO Industri A/S, Copenhagen, Denmark.
Particularly suitable are proteases obtained from a strain of Bacillus having maximum activity throughout the pH-range of 8-12, being commercially availabe from NOVO Industri A/S under the tradenames of Esperase and Savinase. The preparation of these and analogue enzymes is described in GB patent No. 1,243,784. These enzymes are generally presented as granules, e.g. marumes, prils, T-granulates, etc., or liquids and may have enzyme activity of rom 500 to 6,000 Glycine Units/mg. The proteolytic enzyme activity can be determined by the method as described by M. L.Anson in “Journal of general physiology”, Vol. 22 (1938), page 79 (one Anson unit/gram=733 Glycine Units/milligram).
In the compositions of the invention, proteolytic enzymes may be present in amounts such that the final use composition of the enzyme component has proteolytic enzyme activity of from about 10 to 10
10
Glycine Units/kilogram, preferably from 10
2
to 10
10
and more preferably 10
4
to 10
9
.
In order to obtain a suitable activity of the proteolytic enzyme, the temperature applied in the prewash zone or step into which the first component containing this enzyme is introduced, is preferably in the range of 30-40° C. For the same reason, the pH of that prewash zone or step is desirably in the range of 9-11.
B

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