Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – Solid – shaped macroscopic article or structure
Reexamination Certificate
2001-11-14
2003-06-17
Webb, Gregory E. (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
Solid, shaped macroscopic article or structure
C510S444000, C510S443000
Reexamination Certificate
active
06579844
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to particulate detergent compositions and methods for making them. Such detergent compositions may be used for any cleaning purposes, in particular for dish-washing or laundry detergents. They may be used directly in the form of particulate detergent compositions or alternatively, may be formed into tablets of detergent composition using any of the well known tabletting methods such as compaction.
BACKGROUND OF THE INVENTION
In order to meet the needs of the consumer, particulate detergents must meet several criteria in addition to providing good cleaning properties. Such additional criteria include: good flow properties so that they can be easily delivered from the container to the washing machine or washing process; good solubility/dispensing so that they will be delivered into the wash effectively; and in addition, particulate detergents must appeal to the consumer aesthetically. Most particulate detergents comprise a primarily white or pale-coloured base with optional colour-contrasting speckles. It has been found that detergents where the base particles vary in hue are judged by the consumer to be undesirable and are even thought by the consumer to provide less effective cleaning.
However, since detergent compositions generally comprise pre-processed detergent components such as agglomerates, blown powder produced by spray drying processes or extrudates, in addition to raw materials, and because the raw materials themselves vary so much in colour, size and/or shape, significant efforts must be made to avoid non-uniformity. In order to address this, considerable efforts and high costs are required to provide detergent particulates with uniform properties.
It would therefore be desirable to find a method for making detergents which enable use of a wider range of active detergent materials such as those with wide variations of colour, shape and/or size, yet to produce detergent particles with good flow properties and good dispensing and dissolving properties in addition to good aesthetic properties.
The present inventors have now found improved particles and methods for making such particles which overcome these problems of the prior art.
SUMMARY OF THE INVENTION
In accordance with the present invention, there is now provided a detergent particle comprising at least two particulate components, a first component of a first colour and a second component of a second colour, the first and second components being adhered to one another, the mean particle size of at least the first or second particulate component being no more than 50% of the mean particle size of the detergent particle.
In accordance with a further aspect of the present invention there is provided a detergent particle having a sphericity index no greater than 1.7 comprising at least two particulate components, a first component and a second component, at least one of the first and second components having a sphericity index greater than 1.7, the first and second components being adhered to one another substantially in the absence of pressure compaction.
In accordance with a further aspect of the present invention there is provided a detergent particle having a geometric mean particle diameter greater than 500 microns, the detergent particle comprising a first particulate component and a second particulate component, the first and second particulate components being adhered to one another substantially in the absence of pressure compaction, the geometric mean particle size of at least one of the first and second components being no more than 50% of the geometric mean particle size of the detergent particle. Preferably at least one of the first and second particulate components has a span of at least 1.7.
In accordance with the present invention, there is also provided a method for making the detergent particles described, comprising contacting the first particulate component and the second particulate component, optionally in the presence of a binder in a moderate to low shear mixing step to adhere the first and second particulate components to one another and detergent composition comprising the claimed detergent particles.
DETAILED DESCRIPTION OF THE INVENTION
The present inventors have found that by selecting a combination of first and second particulate detergent components and forming these into a single particle, the undesirable properties and lack of uniformity can be overcome. Furthermore, these benefits can be achieved without the intensive processing steps which have been used in the prior art, such as formation of particulates from pastes which require lengthy, energy intensive mixing such as high shear mechanical mixing and even extrusion, both of which use compaction pressure to form particulates and require energy intensive drying processes.
In accordance with a first aspect of the present invention, the first and second particulates are differently coloured from one another. Colour difference as used herein refers to the &Dgr;E value as measured using tri-stimulus colorimetry using a D25M Colorimeter manufactured by Hunter Laboratories. In such a colorimeter, L, a and b values are generated for a sample by directing incident light onto a sample of powder at a 45° angle. Incident light is reflected from the sample and collected by photo detectors which are set vertically above the powder sample at 0°. The detectors convert the light intensity into tri-stimulus values (X,Y,Z) as documented by Commission Internationale de l'Eclairage (CIE). These values are then used to form a descriptive colour term on a standard CIELAB colour scale. The method is well documented, for example, in “Industrial Color Technology” by R. Johnston and M. Saltzman, American Chemical Society, 1971.
Using the CIELAB colour scale, L expresses whiteness where L=100 for white samples and L=0 for black samples; a represents red/green where positive numbers indicate redness and negative numbers indicate colours towards the green end of the spectrum; and b represents yellow/blue where positive numbers indicate yellowness and negative numbers indicate blueness.
Thus for the present invention, colour difference is a positive &Dgr;E value between samples of the first and second particulate components where &Dgr;E=(&Dgr;L
2
+&Dgr;a
2
+&Dgr;b
2
), where &Dgr;L is the difference in L value between the first and second particulate components, &Dgr;a is the difference in a value between the first and second particulate components and &Dgr;b is the difference in b value between the first and second particulate components. In particular, in the invention there will generally be a &Dgr;E value of at least 3. The invention is particularly useful for even larger colour differences such as &Dgr;E values of at least 4, or even at least 6 or 8 or even at least 10. A further useful colour definition is whiteness which is represented by W=L-3b. A whiteness value of from 92 to 100 is preferred for the detergent particles of the invention.
As used herein, “sphericity index” refers to the mean value obtained when one measurement is taken of each of 50 particles taken from a sample of particles (either the detergent particles produced according to the invention, or the first or second partiuclates which form the detergent particles), and the value for sphericity index is calculated for each particle based on the following equation: sphericity index=p
2
/(4&pgr;a), where p is the perimeter of the particle and a is the area of the particle as measured using a Leica Q500MC image analysis system. The apparatus consists of a microscope connected to a video camera and computer. Commercially available software such as the Q500 software supplied by Leica is used to analyse the magnified images and to give values for p and a. The sphericity index of a perfect circle is 1.
Thus, in accordance with a further aspect of the invention, the sphericity index of the detergent particle is no greater than 1.7 and the sphericity index of at least one of the first and secon
Donoghue Scott John
Morrison Christopher Andrew
Dressman Marianne
Glazer Julia A.
The Procter & Gamble Co.
Webb Gregory E.
Zerby Kim
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