Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – For cleaning a specific substrate or removing a specific...
Reexamination Certificate
2000-04-26
2001-04-17
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...
C510S152000, C510S155000
Reexamination Certificate
active
06218348
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a process for making personal washing bar that provides effective cleansing, and a refreshing experience while retaining more moisture in the skin, producing lower levels of visual dryness and maintaining a stronger protective barrier than ordinary soap. The process comprises adding salt of specific protic acids to compositions comprising soap, polyalkalene glycol and fatty acid, (in any order) under mixing conditions at elevated temperatures. The personal washing bars made by this process have excellent in-use sensory properties as well as good bar properties.
BACKGROUND
Consumers are increasingly interested in milder ways to cleanse their skin which results in less damage of the skin's natural protective barrier and also leads to the retention of more moisture in their skin. Indeed toilet bars based on synthetic surfactant such as the Dove® Beauty Bar have gained in popularity. Also, milder synthetic based liquids compositions are a growing segment of the market, especially among consumers in the more developed markets around the world.
However, the in-use properties of synthetic based bars and liquids (syndet bars and liquids) are quite different from soap. Synthetic based formulations tend to rinse slowly from the skin, often leave a feeling of a slippery residue remaining on the skin and are perceived not to last as long as soap. For many consumers in warm tropical climates, washing with syndet bars, combo bars and syndet liquids is not perceived to provide the level of cleansing and refreshing in-use sensory experience provided by soap and is a less preferred method of cleansing the skin even though washing with soap is harsher. Furthermore, because of the intrinsic cost of raw materials, packaging (for liquids), and the relatively higher use-up rates, mild syndet and combo bars and liquids makes these products out of reach of most consumers in emerging and developing markets even if they could learn to live with the very different cleansing experience.
There has been a great deal of research and development devoted to making soap bars milder. A recent review is provided by Murahata et al. (
Cleansing Bars for Face and Body: In Search of Mildness,
in Surfactants in Cosmetics, Ed M. Rieger and L. Rhein, 1997 Marcel Dekker, New York). The approaches include incorporation of relatively high levels of cationic polymers, mild synthetic surfactants, and the inclusion of a relatively high level of glycerol (>10%). All of these approaches have their limitations in terms of cost, manufacturing feasibility and impact on sensory properties and cost. One commercially successful approach is a so called “combo bar” of soap and a synthetic surfactant (e.g., acyl isethionate) as used for example in U.S. Pat. No. 4,954,282 to Resch et al. (relating to Lever 2000® type product). Even here, the sensory properties, use-up rates and cost do not match those of soap. Thus, there is a very real need for a method of cleansing the skin that is perceived to provide the refreshing cleansing experience and economy of soap while maintaining better skin care especially in the reduction of barrier damage and the increase in the level of moisture retention relative to common soap.
The present invention provides a process for making soap bars which are perceived as effective in removing oil and dirt from skin and are preferred by consumers who like the sensory properties of soap.
The invention further provides a process for making a bar which provides these cleaning and preferred sensory attributes while causing less damage to the skin's naturally protective barrier and while retaining more moisture in the skin than ordinary soap bars.
The invention further provides a method for making a bar which provides these desirable perceived cleaning, and preferred sensory properties, and delivery of improved skin care, yet has a cost that is comparable with soap. In this context “improved skin care” is defined as causing less damage to the skin's naturally protective barrier, retention of more moisture in the skin, and/or reducing visible dryness than the method of cleansing the skin with an ordinary soap bar.
EP Patent No. 0,707,631 to Chambers et al. discloses a soap bar composition comprising:
(a) 44 to 86.5% by wt. fatty acid soap;
(b) 5 to 30% by wt. polyalkylene glycol;
(c) 2.5 to 20% by wt. C
6
to C
22
fatty acid; and
(d) 6 to 20% water.
wherein ratio of polyalkylene glycol to C
6
to C
22
fatty acid is 1:3 to 3:1 and polyalkylene glycol has MW below 100,000 Dalton. There is no teaching of the specifically defined protic acid salts of the invention; of the ratios of these salts to free fatty acid; or of the sensory (soap-like clean) and skin care benefits (as measured by defined tests) provided when meeting the defined criteria of the invention.
Applicants have filed a continuation-in-part application to the equivalent of the U.S. Chambers application which claims 0.1 to 50% electrolyte and provides enhanced processing benefits. Again there is no teaching of making a bar using the defined protic acid salts; of ensuring the ratios of these salts to free fatty acid is within defined limits or of enhanced skin care benefits attained in following the process.
Applicants have filed an application to Van Gunst et al. disclosing:
(a) 50 to 80% by wt. soap;
(b) 4 to 35% by wt. free fatty acid;
(c) 1 to 10% by wt. selected organic salts; and
(d) about 10% water;
wherein the bar has no more than about 4% synthetic and is processed using standard extrusion equipment.
The reference fails to disclose process for making a bar by adding defined protic acid salts or using ratio of protic acid salts to free fatty acid. The reference fails to disclose enhanced skincare benefits from bars made by such process.
Similarly, U.S. Pat. No. 3,598,746 to Kaniecki discloses soap, free fatty acid and polyalkylene glycol, but fails to recognize sensory properties and skin care benefits as measured in bars made by process of the subject invention.
BRIEF DESCRIPTION OF THE INVENTION
The subject invention provides a process for making a bar having enhanced skin care properties (as measured by defined tests) by adding specifically defined protic acid salts to compositions comprising fatty acid soaps, free fatty acids, and polyalkylene glycol under mixing conditions carried out in a defined temperature range. As noted using these protic acid salts and mixing to obtain defined ratios of the protic acid salts to free fatty acids, applicants have unexpectedly been able to obtain enhanced skin care properties as measured by defined tests while achieving good bar properties (e.g., hardness, low grit) and desirable sensory properties.
More specifically, the invention comprises a process for making a bar having improved skin condition as measured in Controlled Application Wash Tests (measured by reducing the barrier damage as measured by transepidermal water loss, increasing skin hydration as measured by skin conductivity/capacitance, and/or by reducing visual dryness). The process comprises adding 0.1 to 5% by wt., preferably 0.5 to 3% by wt. of a salt of a protic acid having a pKa1 of less than 6, preferably less than 5.5 to the following components:
(a) 25 to 85% by weight fatty acid soap;
(b) polyalkylene glycol having MW of 400 to 25,000, preferably 400 to 10,000 (an amount such to improve skin condition); and
(c) 1 to 35 C
8
-C
22
, preferably C
10
-C
20
, more preferably C
10
-C
18
free fatty acid (saturated and unsaturated, preferably at least saturated).
Further, the mixture of fatty acid soap, free fatty acid, PAG, and protic acid salt is formed under mixing conditions at a temperature of 25 and 45C., preferably at a temperature between 30 and 40° C. and most preferably between 30 and 35° C.
The resulting bar composition should have a molar equivalents ratio of fatty acid to protic acid salt that is preferably between 0.5:1 to 3:1, most preferably between 0.75:1 to 3:1 and the weight ratio of free fatty acid to the sum of weights of PAG plus protic acid salt, i.e.,
Aronson Michael Paul
Azri-Meehan Shana
Chambers John George
Gorman Christine
Leopoldino Sergio Roberto
Koatz Ronald A.
Ogden Necholus
Unilever Home & Personal Care USA , division of Conopco, Inc.
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