Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – Gel or malleable composition
Reexamination Certificate
1999-02-18
2001-07-24
Krynski, William (Department: 1774)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
Gel or malleable composition
C510S121000, C510S140000, C510S158000, C510S470000
Reexamination Certificate
active
06265368
ABSTRACT:
This invention relates to detergent compositions for use in personal washing which are in the form of viscous aqueous liquids or soft solids.
A number of detergent products for personal washing are formulated as viscous liquids, creams or gels. Examples of such products are hair shampoos, shower gels and facial washes. Such products generally contain foaming surfactant, which usually comprises at least 3 wt % of anionic surfactant possibly accompanied by amphoteric, zwitterionic or nonionic surfactant. It is conventional for such products to contain one or more ingredients whose function is to increase the viscosity of the composition.
One possibility is to incorporate a sufficient quantity of electrolyte together with a sufficient quantity of selected surfactant, so that the surfactant is present in a viscous phase, and thus increases the viscosity of the resulting composition.
It is also known to incorporate polymeric materials to enhance viscosity. One category of synthetic polymers used for this purpose are crosslinked polyacrylates, for instance those sold under the trademark Carbopol. Natural polymers have also been used for this purpose, and in particular xanthan gum has been used. Personal washing products, especially shampoos, containing xanthan gum are described in, for example, U.S. Pat. No. 5,151,210 and EP 500423. Personal washing products containing other biological polymers have been described, for example in GB-A-2188060.
A number of polymers of natural origin have the ability to increase the viscosity of water in which they are dissolved. A well known example is agar. A aqueous solution containing a small percentage of agar is a mobile liquid when hot, but when left to cool it forms a gel with sufficient rigidity to maintain its own shape.
The formation of gels by natural polysaccharides arises from interaction between the polymer molecules. Above a temperature referred to as the gel point, this interaction largely disappears and the hot solution of polymer is mobile. When it cools below its gel point, the interaction of polymer molecules enables them to form a continuous and branched network which extends throughout the sample. This can be described as a network extending “from wall to wall” of the container holding the sample.
Gel formation by aqueous solutions of natural polymers can lead to a wide range of physical properties. A so-called strong gel is sufficiently rigid that it cannot flow. When a sample is subjected to mechanical stress, it eventually breaks. A so-called weak gel is able to flow, and natural polysaccharides can be used to produce compositions which have the appearance of mobile liquids, albeit thicker than water. In contrast with the formation of a continuous, branched network, some materials which thicken water do so through merely local, transient entanglement of molecules.
A discussion of polysaccharides gels, including their range of mechanical properties, is found in “gels and gelling” by Allan H Clark which is Chapter 5 in Physical Chemistry of Foods, Schwartzberg and Hartel, editors; published by Marcel Dekker 1992.
In the present specification, the expression “thickened aqueous composition” will be used to denote aqueous compositions with any viscosity greater than that of water.
EP-A-271131 discloses a number of products intended for application to skin and thickened with carrageenan gels. Many of these do not include surfactant. One product disclosed in this document is a cleansing composition containing a nonionic surfactant which produces negligible foam.
We have found that foaming surfactants cannot be incorporated into a number of gels formed by naturally occurring polymers. The surfactant makes the gel unstable and phase separation occurs. Xanthan gum can be incorporated as a thickener in aqueous compositions containing surfactant but the resulting products tend to have a stringy texture and a slimy feel which are not liked by users.
By contrast, however, we have now found that thickened viscous aqueous compositions formed with carrageenan do not phase separate with foaming surfactants and can be used to form personal washing compositions which are in the form of viscous liquids or gels and have a good combination of consumer properties.
According to the present invention, therefore, we provide a thickened aqueous detergent composition having an aqueous phase containing foaming surfactant and carrageenan.
Carrageenans are a class of polysaccharides which occur in red seaweeds. They are linear polysaccharides made up from alternating &bgr;-1,3- and &agr;-1,4-linked galactose residues. The 1,4-linked residues are the D-enantioner and sometimes occur as the 3,6-anhydride. Many of the galactose residues are sulphated.
A number of carrageenan structures have been described and commercial materials are available which approximate to the ideal structures. However, variations between these structures occur, depending on the source of the carrageenan and treatment of it after extraction.
A description of different carrageenan types is given in “Carrageenans” by Norman F Stanley which is Chapter 3 of “Food Gels” edited by Peter Harris, Elsevier, 1990.
Kappa carrageenan is sulphated on the 1,3-linked galactose residues, but not on the 1,4-linked residues. Iota carrageenan is sulphated on both residues. Lambda carrageenan has two sulphate groups on the 1,4-linked residues and one sulphate group on 70% of the 1,3-linked residues. Industrial treatment of lambda carrageenan with base can remove one sulphate group from some of the 1,4-linked residues: the resulting structure is designated theta carrageenan but does not occur naturally.
Commercially available kappa, iota and lambda carrageenans consist predominantly of material approximating to be ideal structures mentioned above.
Aqueous solutions of kappa and iota carrageenan exist as gels. Lambda carrageenan on its own in aqueous solution does not form gels because its molecular structure prevents association between its molecules and consequent structuring in liquids.
Compositions of this invention contain carrageenan and surfactant in an aqueous phase. The carrageenan increases the viscosity of this phase, and in certain forms of the invention the carrageenan does this by forming a continuous network within this aqueous phase.
Compositions of this invention may be intended for use as personal washing products such as shampoos, shower gels, facial washes, or hand cleansers. For this purpose the composition may consist solely of a thickened continuous aqueous phase or it may incorporate suspended particles of a liquid (eg a water-immiscible oil) or of a solid.
The amount of carrageenan in a composition of the invention may be as low as 0.05% by weight of the aqueous phase of the composition, leading to a mobile, but thickened liquid. The amount may be higher, such as at least 0.1, 0.3 or 0.5% by weight. The amount is unlikely to exceed 5% by weight of the aqueous phase of the composition, preferably not over 4% or 3.5% by weight. A preferred weight range is from 0.5 to 2.5% especially 0.7 to 2.0%.
More than half of the carrageenan may preferably be kappa or iota carrageenan or a mixture of the two. Lambda carrageenan may be used to form thickened liquid compositions which do not contain a continuous network of associated carrageenan molecules, but nevertheless come within the broadest scope of this invention. Also, lambda carrageenan may be used in mixtures with kappa and/or iota carrageenans.
A composition in accordance with this invention may have an appearance resembling a thickened but still mobile, self-levelling liquid. Alternatively, it may have an appearance which is more characteristic of a soft solid. It may be a soft gel, which breaks up easily when disturbed, but retains a lumpy appearance. It may be a firm gel, which can retain its shape during handling, although it can be broken up by application of force. In between, a gel may be elastic so as to distort under its own weight, but retain its shape better than a soft gel.
It will generally be necessary to provide a suffici
Aronson Michael Paul
Brown Charles Rupert
Chatfield Robert James
Willis Edwin
Garrett Dawn L.
Koatz Ronald A.
Krynski William
Lever Brothers Company Division of Conopco, Inc.
LandOfFree
Aqueous detergent compositions thickened using carrageenan does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Aqueous detergent compositions thickened using carrageenan, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Aqueous detergent compositions thickened using carrageenan will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2525232