Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – For cleaning a specific substrate or removing a specific...
Reexamination Certificate
2002-07-17
2004-05-04
Ogden, Necholus (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
For cleaning a specific substrate or removing a specific...
C510S141000, C510S152000, C510S153000, C510S155000, C510S156000
Reexamination Certificate
active
06730643
ABSTRACT:
The present invention relates to transparent soap compositions The invention more particularly relates to transparent soap compositions comprising the salt of 12-hydroxystearic acid or a precursor thereof. The invention also relates to an improved cast route process for making transparent soap that is energy saving, economical and rapid. The process uses less alcohol during processing and lower maturation times than the conventional cast route for making transparent soap.
Transparent soaps have aesthetic appeal and are perceived to be milder than opaque bars. The soaps are transparent due to the fact that the soap is deposited from an alcoholic solution in a transparent, microcrystalline form.
Transparent soaps are usually prepared by the solvent method or the cast route wherein the dried, conventional form of toilet soap is dissolved in boiling ethanol, or the saponification is carried out in an ethanol-water mixture. A clear solution is thus obtained which is then poured into moulds and cooled. The solidified soap obtained is then matured over many weeks to obtain the desired transparent soap. High levels of ethanol or polyhydric alcohols like glycerol and poly(ethylene glycol) are usually required to achieve good transparency.
The term maturation refers to the slow evaporation of alcohol and water from the soap mass, until the amount of alcohol in the soap is minimal.
In a typical process, fatty acids, typically coconut fatty acid (CNFA), stearic acid, palmitic acid and lauric acid are mixed with a polyhydric alcohol like poly(ethylene glycol) or glycerol. Water and ethanol are added, and the whole mixture is saponified. Other ingredients like common salt, ethylene diamine tetraacetic acid (EDTA), antioxidants and synthetic surfactants like sodium lauryl sulphate (SLS) can be optionally added. The mixture is filtered and then placed in a cooler, typically a Schicht cooler. The bars formed are removed, and the ethanol evaporated over a period of at least four to five weeks. The bars are then cut to a desired shape and stored for two to three weeks until most of the ethanol is removed, and bars with good hardness and transparency are obtained.
The fatty acid content of the final soap so obtained is known as the total fatty matter (TFM), and can vary between 40 and 80%.
Other methods known in the art give translucent soaps. Hence the cast route remains the most popular method of making transparent soap. However, one of the disadvantages of making soap by the cast route is that a large amount of ethanol is used in the process, which can be hazardous. Also, maturation times for making the soap are very long, and can range from 6 to 8 weeks. Hence, there has always been a need in the industry to cut down the maturation time, as well as minimise or eliminate the use of volatile alcohol in the process of manufacture using the conventional cast route, whilst retaining the hardness and transparency of soaps produced by the cast route. Further, the same has to be achieved in an economical manner.
U.S. Pat. No. 4,988,453 (Lever Brothers Company) discloses translucent soap bars comprising 30 to 45% by weight of soap with respect to the total bar, 5 to 15% of a monohydric alcohol and 5 to 15% by weight of a dihydric alcohol by weight of the soap bar. The combination of monohydric alcohol and polyhydric alcohol is said to promote translucency. It is claimed that the process avoids long maturation times.
JP 04328200 (Junsei Sangyo My Skincare Lab) relates to transparent soaps containing 16 to 25% sodium tetradecane sulphonate, 25-30% of a soap substrate, 20-28% propylene glycol, 10-15% glycerol and water. Transparency is said to be imparted by the glycerol or other agents like sucrose and polyols. Ethanol is not used in the process, and the soap is prepared by pouring a molten solution, solidifying through cooling and cutting. It is claimed that the soap eliminates the process of drying and maturation.
JP10147800 (Yotsuba Yuka KK) relates to soap compositions good in transparency, hardness and foaming that can be produced without using ethanol. Anionic surfactants including higher fatty acid salt and an acylamino acid salt, water and a polyhydric alcohol are used in the process.
The transparent soap bars of JP 04328200 and JP10147800 disclose the use of high levels of non-soap detergents that are expensive. Further the transparent soaps of the above patents use high levels of polyhydric alcohols to achieve transparency. Polyhydric alcohols are expensive, and when used at high levels can cause the soap to become soft and sticky. Hence, it is not advantageous to employ these processes to obtain transparent soap bars.
JP 64000200 (Nippon Oils and Fats) relates to preparation of transparent soap by kneading the soap composition by a biaxial kneading extruder and moulding the product obtained into a desired shape. The agent imparting transparency is a polyhydric alcohol. The soap does not require maturation.
WO 9503391 and WO 9503392 (Unichema Chemie B. V.) relate to a process for making transparent or translucent soap in which the soap is subjected to enough mechanical working and shear to induce transparency. Mechanical working and shear can be carried out using a Z-blade mixer, rolling mills or cavity transfer mixers. The soap contains 60 to 80% by weight of an alkali metal soap of saturated or unsaturated fatty acids and from 5 to 20% by weight of polyhydric alcohols and can optionally contain up to 20% hydroxystearic acid.
The above patents deal with mechanical processes to obtain transparent bars. It is known that the cast route is a preferred route and provides for superior transparency than the mechanical route.
U.S. Pat. No. 5,310,495 (Lever Brothers Company) relates to transparent bars said to be of exceptional clarity. The bar comprises a mixture of alkanolammonium and alkali metal fatty acid salts and a liquid solvent system including water and free alkanolamine. The bar does not require the use of expensive fatty acids/oils like castor oil or ricinoleic acid. U.S. Pat. No. 2,820,768 (Fromont) and U.S. Pat. No. 4,206,069 (Borrello) also disclose the use of alkanolammonium soaps including free alkanolamine to provide for transparent soaps.
Alkanolammonium soaps are often used to prepare transparent soaps. Such soaps usually contain free alkanolamine. The process does not use ethanol, and maturation time may also be reduced. However, there are problems with the use of alkanolamines both in terms of safety and cost, and it is desirable to manufacture transparent soap without using alkanolamines.
GB 2110711 (Unilever) relates to detergent bar compositions that contain at least 30% tallow soap and 3 to 30% by weight of a soluble salt of 12-hydroxystearic acid. However, the bars are not transparent soaps.
JP 63057699 (Shiseido) relates to transparent gel compositions that comprise hexagonal crystalline liquid phase of fatty acid soap, polyhydric alcohol and water. The fatty acid can be 12-hydroxystearic acid.
Soap compositions comprising 12-hydroxystearic acid are present in the form of transparent gels or opaque soap compositions. WO 95/03391 and WO 95/03392 disclose processes to make transparent soap compositions comprising 12-hydroxystearic acid, however these are prepared by the mechanical route, the disadvantages of which have been set out earlier.
Thus the prior art does not teach the preparation of transparent soaps by the cast route by a process wherein the use of alcohol is minimised and the maturation times reduced without compromising properties of the soap such as transparency, hardness and good foaming.
The present applicants have now found that the cast route can achieve the same by the saponification of 12-hydroxystearic acid (or hardened castor oil) along with other fatty acids and/or oils in the presence of polyhydric alcohols and water. The alcohol required during saponification is eliminated or greatly reduced by using the process of the invention. The maturation time is also reduced using the process of the invention. Further the total fatty matter can also be reduced
Chokappa Dhanraj Kalyansundaram
Dhanuka Vinodkumar Ramniranjan
Mhatre Subhash Shivshankar
Bornstein Alan A.
Ogden Necholus
Unilever Home & Personal Care USA Division of Conopco, Inc.
LandOfFree
Detergent bar and a process for manufacture does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Detergent bar and a process for manufacture, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Detergent bar and a process for manufacture will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3199627