Modern laundry compositions either for use in domestic or industrial care comprise a number of ingredients, sometimes more than 30 different actives. For most of these ingredients, it is essential that they dissolve quickly and completely in the wash liquor to deliver optimum performance. It is known in the art that the dissolution profile of each ingredient depends on certain conditions, e.g., nature of the ingredient, the temperature in the wash liquor, and the degree of hardness of the wash liquor, to name just a few. It is particularly true, that dependent on the hardness of the wash liquor the solubility of many laundry detergent ingredients is influenced in such a way that the higher the hardness of the wash liquor, the lower is the solubility of many laundry detergent ingredients and hence the lower is the performance of a given laundry detergent composition.
One way to overcome this disadvantage of low performance is to overdose. However, due to higher costs for the consumer and due to the environmental impact of overdosing, the detergent industry is seeking for different solutions. One better way is the use of specific water treatment compositions comprising chelating agents to complex free calcium ions, which are basically responsible of the hardness of water. This approach has a number of drawbacks: one being the additional costs for the consumer, another one being the inconvenience for the consumer to add another composition in the drawer of the washing machine. The main problem associated with this approach to overcome this disadvantage however is the fact that the hardness of the wash water varies from location to location and even changes over time so that the consumer is not always aware of the actual water hardness in his neighborhood at the time he wants to run a laundry cycle.
The present invention overcomes this problem and provides compositions with improved dissolution profile, particularly when fast dissolution is critical to get the optimum performance of actives under hard water conditions.
The present invention utilizes cyclodextrin as carrier for laundry treatment actives. It has been found that a complex of cyclodextrin and at least one laundry treatment active is more soluble in water and provides better solubility than the laundry treatment active alone.
The use of cyclodextrin is known in the art as an efficient carrier for cosmetics and drugs. U.S. Pat. No. 6,407,079 (Janssen Pharmaceutica, published Jun. 18, 2002) discloses pharmaceutical compositions comprising inclusion compounds of sparingly water-soluble or water-insoluble drugs with beta-cyclodextrin ethers or beta-cyclodextrin esters. U.S. Pat. No. 6,432,928 (Chinoin Gygyszer, published Aug. 13, 2002) provides inclusion complexes of cyclodextrin derivatives with taxol and its derivatives for use in the pharmaceutical industry.
Cyclodextrin is also known in the art as a malodor control agent able to capture malodorous molecules in its cavity. U.S. Pat. No. 6,284,231 (P&G, published Sep. 04, 2001) discloses stable, aqueous odor-absorbing compositions, comprising uncomplexed cyclodextrin entities.
Cyclodextrin has also been used to carry hydrophobic and therefore relatively water-insoluble perfumes into hydrophilic environments. U.S. Pat. No. 6,287,603 (Nestec, published Sep. 11, 2001) discloses a cyclodextrin flavor delivery system comprising inclusion complexes of cyclodextrin and perfumes.
U.S. Pat. No. 6,133,215 (CIBA, published Oct. 17, 2000) discloses a white crystal form of a fabric brightener which is obtained when adding a polyol, such a glycerine, ethylene glycol and/or other polyols, to a solution of a fabric brightener in water or ethanol. Cyclodextrin is disclosed as an absorbent filler/carrier and added as solid material during the process.
It has been found that the process of U.S. Pat. No. 6,133,215 has some drawbacks including agglomeration and caking of cyclodextrin when adding it into the reaction vessel. The material obtained by the processes of U.S. Pat. No. 6,133,215 is not suitable for incorporation into the detergent compositions of the present invention. The present invention therefore suggests compositions comprising complexes of cyclodextrin and at least one laundry treatment active, prepared by following certain steps. Complexes prepared in such a way are suitable for incorporation into the detergent compositions of the present invention.