Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – Heterogeneous arrangement
Reexamination Certificate
2000-10-25
2002-04-02
Ogden, Necholus (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
Heterogeneous arrangement
C510S446000, C510S447000, C510S481000, C510S488000
Reexamination Certificate
active
06365567
ABSTRACT:
The present invention relates to melt-cast solid shaped detergent compositions.
Detergent tablets are conventionally manufactured by one of the two methods: (i) shear working/homogenisation of the formulation followed by extrusion and stamping, or (ii) casting.
In the manufacture of detergent tablets by shear working and extrusion the amount of water that can be incorporated into the formulation is less than ~15%. These systems are multiphase composites which exhibit “bricks suspended in mortar” type of morphology. The bricks are solid particles, which in the case of toilet soaps are crystalline salts of long chain saturated fatty acids, inorganic fillers, etc. The mortar is a mixture of various lyotropic liquid crystalline or isotropic solution phases comprising water, liquid additives, and relatively water soluble soaps or surfactants. These compositions would typically comprise of 50-60% solids, 20-30% Lyotropic liquid crystalline phases and about 10% isotropic liquid.
In the manufacture of detergent compositions by casting the formulated system is taken to a fluid state by raising the temperature, filled into moulds, and cooled. This technology is commonly employed for manufacturing transparent personal wash tablets that contain among other ingredients (such as soap and synthetic surfactants) typically 15-50% of expensive components such as ethanol, polyhydric alcohols, sugars, etc at the time of casting. U.S. Pat. No. 4,165,293 (Amway, 1979); WO 96/04361 (P&G, 1996) discloses a solid transparent soap bar comprising soap, synthetic surfactants and a water soluble organic solvent such as e.g. propylene glycol. The level of water in these compositions is about 10-32%.
The problem in manufacturing non-transparent detergent tablets by casting is that the typical compositions do not form a pourable liquid at elevated temperatures. U.S. Pat. No. 5,340,492 (P&G, 1994) claims a castable composition having a three-dimensional skeleton structure comprising a relatively rigid, interlocking mesh of neutralised crystalline carboxylic acids (soap), synthetic surfactants and high levels of water and other liquids. However, the patent does not demonstrate the claims without employing about 15% propylene glycol in the composition.
The compositions claimed in U.S. Pat. No. 5,340,492 will be soft, exhibiting an yield stress of less than 75 kPa as measured using a cheese wire cutter apparatus, and hence can not be employed as firm tablets which are rigid enough to be conveniently held in hand for use. In order to increase the rigidity of the bar the examples in the patent employ ingredients such as polyols (e.g. propylene glycol) in the composition, under the guise of so called “bar appearance aids”. The patent does not disclose any composition without the incorporation of “bar appearance aids” when synthetic surfactants are also present in the composition. These bar appearance aids are expensive and also reduce the amount and speed of lather.
The object of the present invention is to obtain solid shaped detergent compositions, with very high levels of water or liquid benefit agents, that are rigid and economical while maintaining good in-use properties.
It has now been found that the incorporation of low amounts of salting-in electrolytes in melt-cast detergent compositions comprising very high levels of water or liquid benefit agents result in rigid solid shaped articles exhibiting an yield stress greater than 75 kPa as measured using a cheese wire cutter apparatus. These compositions can be held in hand, are economical, high foaming and demonstrate good in-use properties.
Thus according to a first aspect of the invention, there is provided a melt-cast solid shaped detergent composition comprising:
a) 2-60% of a water insoluble structurant;
b) 2-50% of a detergent active species;
c) 0.5-30% of a salting-in electrolyte;
d) 30-80% water;
and optionally other liquid benefit agents.
According to a preferred aspect the invention relates to a melt-cast solid shaped detergent composition comprising:
a) 2-50% of a water insoluble structurant selected from saturated fatty acid soap comprising one or more of neutralised C
6
-C
24
fatty acids,
b) 2-40% of a detergent active species,
c) 0.5-20% of a salting-in electrolyte, and
d) 30-80% water
and optionally other liquid benefit agents.
According to a more preferred aspect the invention relates to a melt-cast solid shaped detergent composition comprising:
a) 5-40% of a saturated fatty acid soap comprising one or more of C
12
-C
24
fatty acids,
b) 2-20% of a detergent active species,
c) 0.5-15% of a salting-in electrolyte, and
d) 35-70% water
and optionally other liquid benefit agents.
It is preferred that the detergent active is predominantly non-soap.
According to another aspect of the invention there is provided a process for manufacturing the solid shaped detergent composition comprising the steps of:
a) making a melt of the above composition,
b) pouring the said melt into a mould to obtain the desired shape, and
c) cooling the mould under quiescent conditions to bring about solidification.
According to a preferred aspect of the invention there is provided a process for manufacturing cast-in-pack solid shaped detergent composition comprising the steps of:
a) making a melt of the above composition,
b) pouring the said melt into a pre-formed polymeric mould to obtain the desired shape,
c) sealing the mould, and
d) cooling the mould under quiescent conditions to bring about solidification.
The present invention relates to melt-cast solid shaped detergent compositions that essentially comprise salting-in electrolytes, and a process for manufacturing the same.
The solid shaped articles of the composition according to the invention are rigid enough to be conveniently held in the hand, are economical, high foaming, and exhibit good in-use properties. The compositions exhibit yield stress values greater than 75 kPa as measured using the cheese wire cutter apparatus.
Salting-in electrolytes for use in the composition are selected from those listed in the ‘Hofmeister’ or ‘Lyotropic’ series. The salting-in electrolytes are generally those wherein the lyotropic number for the anion of the electrolyte is >10. Some examples of anions with lyotropic number >10 are NO
2
−
, ClO
3
−
, Br
−
, NO
3
−
, ClO
4
−
, I
−
, CNS
−
, C
6
H
5
SO
3
−
, C
6
H
4
CH
3
SO
3
−
and Cr
2
O
7
2−
. The preferred examples of salting-in electrolytes for use in compositions according to the present invention are alkali metal salts of the above mentioned anions. The most preferred examples of the salting-in electrolytes for use in compositions according to the present invention are sodium toluene sulphonate, sodium cumene sulphonate and sodium xylene sulphonate. Further examples of salting-in electrolytes may be selected form those described in (i) Collins, K. D.; Washabaugh, M. W. Quart. Rev. Biophys., 1985, 18, 323; (ii) Schuster. P, Zundel. G and Sandorfy. C, 1976, ‘The Hydrogen Bond’, Recent developments in theory and experiments, Vol. III, North-Holland Publishing Co. Amsterdam, N.Y., Oxford.
Water insoluble structurants are preferably selected from saturated fatty acid soap comprising one or more of C
6
-C
24
fatty acids. The term soap denotes salts of carboxylic fatty acids. The soap employed as water insoluble structurant may be a sodium, potassium, magnesium, aluminium, calcium or lithium salt of saturated fatty acids. It is especially preferred to have soap obtained as sodium or potassium salt of saturated fatty acid. The soap may be obtained from one or more of C
12
-C
24
saturated fatty acids.
The water insoluble structurant in the composition is preferably 5-50% by weight and more preferably 5-40% by wt. of the composition.
The compositions according to the invention comprise detergent actives that may be soap or non-soap based. It is preferable to employ non-soap detergent actives that are selected from anionic, non-ionic, cationic, amphoteric or zwitterionic surfactants or their mixtures.
Suitable anionic
Nadakatti Suresh Murigeppa
Naik Vijay Mukund
Thomas Shiju
Koatz Ronald A.
Ogden Necholus
Unilever Home & Personal Care USA
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