Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – Liquid composition
Reexamination Certificate
2002-01-31
2003-12-02
Gupta, Yogendra N. (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
Liquid composition
C510S338000
Reexamination Certificate
active
06656899
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to liquid laundry detergent products which are non-aqueous in nature and which are in the form of stable dispersions of particulate material and preferably also include other materials such as bleaching agents and/or conventional detergent composition adjuvants.
BACKGROUND OF THE INVENTION
Liquid laundry detergent products offer a number of advantages over dry, powdered or particulate laundry detergent products. Liquid laundry detergent products are readily measurable, speedily dissolved in wash water, non-dusting, are capable of being easily applied in concentrated solutions or dispersions to soiled areas on garments to be laundered and usually occupy less storage space than granular products. Because liquid laundry detergents are usually considered to be more convenient to use than granular laundry detergents, they have found substantial favor with consumers.
However, while liquid laundry detergents have a number of advantages over granular laundry detergent products, there are also disadvantages entailed in using them. In particular, laundry detergent composition components which may be compatible with each other in granular products may tend to interact or react with each other in a liquid, and especially in an aqueous liquid environment. Components such as peroxygen bleaches and bleach precursors can be especially difficult to incorporate into liquid laundry detergent products with an acceptable degree of compositional stability. Poor compositional stability may cause some active ingredients to react with each other prematurely in the product which can cause physical instabilities such as phase splitting, sedimentation and solidification. This premature reaction may also cause chemical instabilities which can lead to product discoloration or color change, oxygen gas liberation, oxidation of sensitive ingredients (especially enzymes) and eventually detersive performance loss.
One approach for enhancing the chemical compatibility and stability of liquid laundry detergent products has been to formulate non-aqueous (or anhydrous) liquid laundry detergent compositions. Generally, the chemical stability of the components of a non-aqueous liquid laundry detergent composition increase as the amount of water in the laundry detergent composition decreases. Moreover, by minimizing the amount of water in a liquid laundry detergent composition, one can maximize the surfactant activity of the composition. Non-aqueous liquid laundry detergent compositions have been disclosed in Hepworth et al., U.S. Pat. No. 4,615,820, Issued Oct. 17, 1986; Schultz et al., U.S. Pat. No. 4,929,380, Issued May 29, 1990; Schultz et al., U.S. Pat. No. 5,008,031, Issued Apr. 16, 1991; Elder et al., EP-A-030,096, Published Jun. 10, 1981; Hall et al., WO 92/09678, Published Jun. 11, 1992 and Sanderson et al., EP-A-565,017, Published Oct. 13, 1993.
However, certain common detergent ingredients such as builders and alkalinity sources (i.e. buffers) are not generally soluble in most non-aqueous solvents and because these ingredients are typically denser than the liquid matrix of a non-aqueous detergent composition, they have a tendency to separate out of liquid detergent products and form sediments on the bottom of the detergent container between their manufacture and usage by the consumer. This segregation can in turn have an adverse affect on product aesthetics, usage instructions, pourability, dispensability, stability and in particular on the overall cleaning effectiveness. These affects are accentuated when such compositions must stand for prolonged periods of times during shipping and storage.
This observed segregation and separation behavior is related to the fact that the density of the solid suspended phase is higher than the density of the liquid phase. According to Stokes' Law the rate of segregation of a solid particle suspended in a liquid medium varies proportionately with the difference between the density of the suspended particles and the density of the liquid.
Given the foregoing, there is a continuing need to incorporate solid particulates comprising ingredients which are insoluble in a non-aqueous detergent liquid (e.g. certain builders, alkalinity sources, bleach, bleach activators etc.) without undesirable separation and sedimentation by the solid particulates. Accordingly, it is a benefit of the present invention to provide non-aqueous liquid laundry detergent compositions which have excellent cleaning and detersive performance without displaying deleterious separation and segregation phenomena.
SUMMARY OF THE INVENTION
It has now been discovered in the present invention that solid particulates may be added to and suspended in a non-aqueous laundry detergent composition without undesirable separation and sedimentation of the solid particulates by including, in addition to the solid particulates, low-density filler particles which reduce the tendency of the suspended solid particulates to separate out of the laundry detergent composition and sendiment. These low-density filler particles are themselves insoluble in the non-aqueous liquid phase of the detergent composition but dissolve in the wash liquor formed when the detergent composition is mixed with water inside an automatic washing machine and then subsequently carried away in the wash liquor when it is emptied from the washing machine.
The non-aqueous liquid detergent compositions according to a first aspect of the present invention comprise from about 20% to about 99.95% by weight of the composition of a surfactant-containing non-aqueous liquid phase; and from about 1% to about 80% by weight of the composition of a suspended solid particulate phase comprising low-density filler particles and adjuvant detersive particles wherein the low-density filler particles are substantially insoluble in said liquid phase and are substantially soluble in a wash liquor. The low-density filler particles may optionally be enrobed with coating ingredients.
The present invention further encompasses a process for continuously preparing low-density filler particles which are coated with certain detergent ingredients. In the first step of the process water and adjuvant detersive components are continuously mixed to form an aqueous solution. The microspheres are made from a material which is substantially insoluble in the non-aqueous liquid phase and substantially soluble in water and have a particle size of the microspheres is less than about 100 &mgr;m. These microspheres are added to the aqueous solution to form a slurry. The slurry is then dried in a spray-dryer.
All parts, percentages and ratios used herein are expressed as percent weight unless otherwise specified. All documents cited are, in relevant part, incorporated herein by reference.
DETAILED DESCRIPTION OF THE INVENTION
Definitions—As used herein, “non-aqueous” or “anhydrous” are used synonymously and both describe a fluid in which the water content is less than about 5%.
By “wash-water” and “wash liquor” it is meant a mixture of water and the non-aqueous detergent composition taught herein. This “wash-water” and “wash liquor” is most typically contained in an automatic washing machine, but it may also be contained in a bucket, sink or any other container capable of holding a liquid.
By “wash-water soluble” or “soluble in the wash-water” or “soluble in the wash-liquor” it is meant that a particular type of material dissolves sufficiently in a wash-liquor or wash-water that the material will not be trapped and deposited as an undesirable residue on textiles or garments immersed the wash-liquor or wash-water.
By “encapsulated” and “enrobed” it is meant that the coating ingredients described below cover at least a majority of the outer surface of the low-density coated particles.
By “median” or “average” particle size it is meant the “mean” particle size in that about 50% of the particles are large and about 50% are smaller than this particle size as measured by standard particle size analysis techniques.
By “density” it is meant the density of
Aouad Yousef Georges
Sadlowski Eugene Steven
Cook C. Brant
Gupta Yogendra N.
Matthews Armina E.
Petruncio John M
The Procter & Gamble & Company
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