Syndet bar composition

Abstract

The invention relates to a syndet bar composition comprising sulfonated methyl ester of a fatty acid having a chain length of 16 to 18 carbon atoms (C16-C18), wherein the sulfonated methyl ester is present in an amount of 5% to 30% by weight of the composition; a co-surfactant selected from the group consisting of alkyl sulfosuccinate, alkyl sulfate, alkyl ether sulfate, alkyl polyglu-coside, or the combination thereof; a fatty alcohol selected from the group consisting of cetyl alcohol, stearyl alcohol or cetostearyl alcohol; a saturated fatty acid; a filler; and a humectant/moisturiser. The syndet bar composition is useful as a personal cleaning, laundry or dishwashing bar.

Claims

1. A syndet bar composition comprising: sulfonated methyl ester of a fatty acid having a chain length of 16 to 18 carbon atoms (C16-C18), wherein the sulfonated methyl ester is present in an amount of 5% to 30% by weight of the composition, wherein the sulfonated methyl ester is a compound containing 60% to 90% of C16 sulfonated methyl ester and 10% to 40% of C18 sulfonated methyl ester by weight of the compound; a co-surfactant selected from the group consisting of alkyl sulfosuccinate, alkyl sulfate, alkyl ether sulfate, alkyl polyglucoside, and combinations thereof; a fatty alcohol, in an amount of 5% to 20% by weight of the composition, selected from the group consisting of cetyl alcohol, stearyl alcohol, and cetostearyl alcohol; a saturated fatty acid; a filler; and a humectant/moisturiser, wherein apart from impurities, the syndet bar composition is free of fatty acid salts.

2. The syndet bar composition according to claim 1, wherein the co-surfactant is present in an amount of 1% to 40% by weight of the composition.

3. The syndet bar composition according to claim 1, wherein the alkyl sulfosuccinate is disodium lauryl sulfosuccinate.

4. The syndet bar composition according to claim 1, wherein the alkyl sulfate is sodium lauryl sulfate, potassium lauryl sulfate, or a combination thereof.

5. The syndet bar composition according to claim 1, wherein the alkyl ether sulfate is sodium lauryl ether sulfate.

6. The syndet bar composition according to claim 1, wherein the co-surfactant comprises disodium lauryl sulfosuccinate.

7. The syndet bar composition according to claim 1, wherein the co-surfactant comprises sodium lauryl sulfate, potassium lauryl sulfate, or a combination thereof.

8. The syndet bar composition according to claim 6, wherein the co-surfactant further comprises sodium lauryl sulfate, potassium lauryl sulfate, or a combination thereof.

9. The syndet bar composition according to claim 6, wherein the co-surfactant is present in an amount of 1% to 40% by weight of the composition.

10. The syndet bar composition according to claim 8, wherein the co-surfactant is present in an amount of 1% to 40% by weight of the composition.

11. The syndet bar composition according to claim 1, wherein the saturated fatty acid is present in an amount of 1% to 30% by weight of the composition.

12. The syndet bar composition according to claim 1, wherein the saturated fatty acid is stearic acid, palmitic acid, lauric acid, or a combination of any two or more thereof.

13. The syndet bar composition according to claim 1, wherein the filler is present in an amount of 1% to 40% by weight of the composition.

14. The syndet bar composition according to claim 1, wherein the filler is wheat starch, corn starch, rice starch, barley starch, oat, tapioca, talcum, sodium sulfate, or a combination of any two or more thereof.

15. The syndet bar composition according to claim 1, wherein the humectant/moisturiser is present in an amount of 1% to 10% by weight of the composition.

16. The syndet bar composition according to claim 1, wherein the humectant/moisturiser is glycerin, water, urea, sodium lactate or a combination of any two or more thereof.

17. The syndet bar composition according to claim 1 further comprising an anti-cracking agent in an amount of 1% to 15% by weight of the composition.

18. The syndet bar composition according to claim 17, wherein the anti-cracking agent is a hydrogenated vegetable oil, polyethylene glycol, or a combination thereof.

19. A syndet bar composition having the following ingredients: (1) sulfonated methyl ester of a fatty acid having a chain length of 16 to 18 carbon atoms (C16- C18), in an amount of 10-30% by weight; (2) disodium lauryl sulfosuccinate, in an amount of 5-20% by weight; (3) potassium lauryl sulfate, in an amount of 5-20% by weight; (4) cetearyl alcohol, in an amount of 5-15% by weight; (5) stearic acid, in an amount of 5-15% by weight; (6) hydrogenated castor oil, in an amount of 5-10% by weight; (7) wheat starch, in an amount of 10-30% by weight; (8) glycerine, in an amount of 1-10% by weight; and (9) water, with the total weight of (1)-(9) being 100%.

20. A syndet bar composition characterized as i) having the following ingredients: (1) sulfonated methyl ester of a fatty acid having a chain length of 16 to 18 carbon atoms (C16- C18), in an amount of 10-30% by weight; (2) disodium lauryl sulfosuccinate, in an amount of 5-20% by weight; (3) potassium lauryl sulfate, in an amount of 5-20% by weight; (4) stearyl alcohol, in an amount of 5-15% by weight; (5) palmitic acid, in an amount of 5-15% by weight; (6) polyethylene glycol, in an amount of 1-10% by weight; (7) corn starch, in an amount of 10-30% by weight; (8) glycerine, in an amount of 1-10% by weight; and (9) water, or ii) having the following ingredients: (1) sulfonated methyl ester of a fatty acid having a chain length of 16 to 18 carbon atoms (C16- C18), in an amount of 10-30% by weight; (2) disodium lauryl sulfosuccinate, in an amount of 5-20% by weight; (3) potassium lauryl sulfate, in an amount of 5-20% by weight; (4) cetyl alcohol, in an amount of 5-15% by weight; (5) lauric acid, in an amount of 5-15% by weight; (6) hydrogenated castor oil, in an amount of 1-10% by weight; (7) wheat starch, in an amount of 10-30% by weight; (8) glycerine, in an amount of 1-10% by weight; (9) titanium dioxide, in an amount of 0.1-0.5% by weight, and (10) water, wherein the total weight of (1)-(9) in i) or (1)-(10) in ii) is 100%.

Description

DETAILED DESCRIPTION OF THE INVENTION

(1) Hereinafter, the invention shall be described according to the preferred embodiments of the invention and by referring to the accompanying description and drawings. However, it is to be understood that limiting the description to the preferred embodiments of the invention and to the drawings is merely to facilitate discussion of the invention and it is envisioned that those skilled in the art may devise various modifications without departing from the scope of the appended claim.

(2) The invention discloses a syndet bar composition comprising SME of a fatty acid having a chain length of 16 to 18 carbon atoms (C16-C18), wherein the SME is present in an amount of 5% to 30% by weight of the composition; a co-surfactant selected from the group consisting of alkyl sulfosuccinate, alkyl sulfate, alkyl ether sulfate, or the combination thereof; a fatty alcohol selected from the group consisting of cetyl alcohol, stearyl alcohol or cetostearyl alcohol; a saturated fatty acid; a filler; and ahumectant/moisturiser.

(3) SME is used in the syndet bar composition as the surfactant which provides detergency as well as beneficial effects to the skin, for example natural, mild and softening effects. By the term surfactant or surfactant system, it refers to a compound or compounds that are capable of lowering the surface tension or interfacial tension between a liquid and a gas or between two liquids or between a liquid and a solid. Therefore, surfactant is useful as wetting agents, emulsifiers, or detergents.

(4) According to an embodiment of the invention, the SME used in the syndet bar composition is a long carbon chain SME of a fatty acid, having a chain length of 16 to 18 carbon atoms (i.e. C16-C18 SME). C16 SME and C18 SME, respectively, have the molecular structures as shown in the Formula (I) and Formula (II) below:

(5) ##STR00001##

(6) ##STR00002##

(7) Both C16 and C18 SME can be derived from a natural source, such as plant oils (vegetable oils) or animal fats, including palm oil. Specifically, C16 SME can be obtained from the palmitic acid; while C18 SME can be obtained from stearic acid of palm oil. Both of these SMEs were obtained via sulfonation of methyl ester.

(8) As set forth in the preceding description, SME is present in the syndet bar composition in an amount of approximately 5% to 30% by weight of the composition. For example, it can be present in an amount of 5% to 25%, or 10% to 25%, or 15% to 20% by weight of the composition.

(9) In certain embodiments, the SME used in the syndet bar composition is a compound (blend, or mixture) containing C16 SME and C18 SME in a specific combination ratio. Preferably, the SME compound of the invention can contain approximately 55% to 99% of C16 SME and approximately 1% to 45% of C18 SME by weight of the compound. For example, the SME compound can be a blend of 60% to 90% of C16 SME and 10% to 40% C18 SME, or a blend of 65% to 85% of C16 SME and 15% to 35% C18 SME. Alternatively, the SME compound can also be a blend of 90% to 99% of C16 SME and 1% to 10% C18 SME.

(10) Asides from having SME as the major surfactant, the syndet bar composition of the invention also contains a co-surfactant, which can be present in an amount of approximately 1% to 40% by weight of the composition. In certain embodiments, the co-surfactant can be an alkyl sulfosuccinate, such as disodium lauryl sulfosuccinate; or an alkyl sulfate such as SLS, potassium lauryl sulfate, or a combination thereof; or an alkyl ether sulfate such as SLES; or an alkyl polyglucoside. Without wishing to be bound by the theory, SME, in the presence of the co-surfactant, is expected to produce a synergistic effect in the detergency of the syndet bar. It is appreciated that SLES, if added, should be used in a small quantity (e.g. 2% to 3% by weight of the composition) in order to prevent any undesired properties of the syndet bar produced, for instance, to prevent the bar from being oily and sticky when used.

(11) The co-surfactant is added to the composition to provide good detergency and foaming property. In certain embodiments, the combination of main surfactants and co-surfactants is also capable of reducing skin irritation. For example, the addition of green surfactant, such as alkyl polyglucoside (APG), to linear alkylbenzene sulfonate (LAS) can reduce the irritation of LAS. Alternatively, a combination between APG and SLES in a specific ratio may also reduce the irritation of SLES.

(12) In accordance with another embodiment of the invention, the syndet bar composition also contains a fatty alcohol, which is present in an amount of approximately 1% to 30% by weight of the composition. For example, the fatty alcohol can be present in an amount of 5% to 20% by weight of the composition. As set forth in the preceding description, the fatty alcohol used in the invention can be cetyl alcohol, stearyl alcohol or cetostearyl alcohol (i.e. a mixture of cetyl alcohol and stearyl alcohol). The fatty alcohol plays a role of structurant and emollient in the syndet bar composition. As the fatty alcohol also functions as an anti-cracking agent, the combination between the fatty alcohol (e.g. cetostearyl alcohol) and SME is capable of providing an improved softening as well as anti-cracking effect to the syndet bar.

(13) Apart from fatty alcohol, the syndet bar composition of the invention also contains saturated fatty acid, which also functions as structurant and emollient that enhances the role of the fatty alcohol. In certain embodiments, the inclusion of long chain fatty acid can also help in hardening the syndet bar. Preferably, the saturated fatty acid is present in an amount of approximately 1% to 30% by weight of the composition. The saturated fatty acid can be stearic acid, palmitic acid, lauric acid, or a combination of any two or more thereof, according to one of the embodiments of the invention. One of the preferred saturated fatty acids that can be used in the syndet bar composition is triple pressed stearic acid. In certain embodiments, the triple pressed stearic acid can be present in an amount of 5% to 20% by weight of the composition.

(14) In accordance with another embodiment of the invention, the syndet bar composition also contains filler. The filler can be present in an amount of approximately 1% to 40% by weight of the composition. Specifically, the filler can be present in an amount of 10% to 30% by weight of the composition. In certain embodiments, the filler is wheat starch, corn starch, rice starch, barley starch, oat, tapioca, talcum, sodium sulfate, or a combination of any two or more thereof.

(15) A humectant/moisturiser is present in an amount of approximately 1% to 10% by weight of the composition, according to another embodiment of the invention. For example, the humectant/moisturiser can be present in an amount of approximately 1% to 10% by weight of the composition. Preferably, the humectant/moisturiser is glycerin, water, urea, sodium lactate or a combination of any two or more thereof. Humectant/moisturisers such as glycerin and water can also serve as binders, which cohesively bind the constituting ingredients of the syndet bar composition to form the soap bar.

(16) Further embodiment of the invention discloses that the syndet bar composition further comprises an anti-cracking agent in an amount of 1% to 15% by weight of the composition. For example, the anti-cracking agent can be a hydrogenated vegetable oil, polyethylene glycol or a combination thereof. Preferably, the anti-cracking agent can be a hydrogenated castor oil. Syndet bar may sometimes be difficult to be shaped. In order to increase the hardness of the syndet bar for different applications, the weight percentage of the hydrogenated vegetable oil can be increased.

(17) The combination of ingredients does not require adjustment on the di-salt content, yet it is capable of providing a hard bar soap due to the specific formulation and the specific blend of ingredients. The syndet bar of the invention is substantially soap-free, mild and produces creamy foam. Therefore, it is suitable to be used by the consumers as a personal cleansing bar. It can also be used as a cleansing agent for animals (e.g. pets) due to its low pH and mild to skin. In certain embodiments, additional ingredients, such as anti-bacterial agents and cysteine, can be added to animal cleansing products. It can also be used industrially or domestically for laundry, dishwashing or hard surface cleaning.

(18) In certain embodiments of the invention, the syndet bar composition can further comprise a preservative, a stabilizing agent, flavouring agent, colouring agent, or a combination of any two or more thereof. As a personal cleansing bar which also provides a skincare effect, the syndet bar composition can further comprise an additive, such as a skin conditioning agent, skin moisturizing agent, skin hydrating agent, oil-controlling agent, soothing agent or whitening agent.

(19) In accordance with another embodiment of the invention, the syndet bar composition can further comprise a nutritious component, such as vitamins and minerals, naturally derived essential oils, bioflavonoids and anti-oxidants, which protects the skin from drying out due to the detergency effect, preventing the skin from external damages by leaving a protective layer to the skin, or improving overall hygiene and health of the skin. For example, the vitamins and minerals can be vitamin E (tocotrienols, tocopherols or the combination thereof), vitamin A, silica, magnesium, calcium, potassium, zinc, copper, selenium, chromium and sulfur. In certain embodiments, titanium dioxide can be added to increase the whiteness of the syndet bar and provide an even colour appearance to the bar.

(20) The syndet bar composition can be prepared in the form of solid bar soaps, or any other suitable solid forms such as soap pellets or soap flakes. Exemplary formulations of this SME-based syndet bar are further detailed in the Examples. The syndet bar can be produced from the various ingredients, via a simple mixing process of powder and liquid ingredients. The process includes the steps of mixing liquid ingredients in a cold process.

(21) The liquid ingredients include the humectant/moisturiser (e.g. glycerine and water) and polyethylene glycol. This can be followed by melting solid ingredients, including the SME, co-surfactant, fatty alcohol, saturated fatty acid and filler, at high temperature. The hot liquids of melted ingredients and the cold liquids from the cold process can be mixed in a screw mixing unit at hot temperature to form a paste, which is subject to a flaking process on a cold drum. The flakes obtained can be packed to form the soap bars.

(22) The performance of the SME-based syndet bar can be tested in comparison to the commercially obtained syndet bar or combo bar. An example of the comparison test, namely, F-test and T-test on the soap bar performance is further detailed in Example 2. As shown in the comparison data in Tables 4 and 5, SME-based syndet bar is shown to provide comparable cleansing as that of the commercially obtained syndet bar or the commercially obtained sodium lauroyl isethionate-based combo soap, while gives rise of an improved softening effect as compared to these commercially obtained soap bars. It can be shown by the experimental data that the syndet bar of the invention is mild and having low irritation. The skin does not feel dry after use of the syndet bar and after washing, and the stratum corneum (uppermost layer of the skin) is intact. Without wishing to be bound by the theory, it is believed that the combination of the active ingredients in the syndet bar can help the stratum corneum to retain water hence showing an effect of skin-softening.

EXAMPLES

(23) Example 1 Syndet Bar Formulation

(24) The SME-based syndet bar can be prepared based on the formulations as shown in Tables 1-3.

(25) TABLE-US-00001 TABLE 1 Ingredient Weight percentage range (% wt) C16-C18 SME 10-30 Disodium lauryl sulfosuccinate 5-20 Potassium lauryl sulfate 5-20 Cetearyl alcohol 5-15 Triple pressed stearic acid 5-15 Hydrogenated castor oil 1-10 Wheat starch 10-30 Glycerine 1-10 Water to 100%

(26) TABLE-US-00002 TABLE 2 Ingredient Weight percentage range (% wt) C16-C18 SME 10-30 Disodium lauryl sulfosuccinate 5-20 Potassium lauryl sulfate 5-20 Stearyl alcohol 5-15 Palmitic acid 5-15 Polyethylene glycol 1-10 Corn starch 10-30 Glycerine 1-10 Water to 100%

(27) TABLE-US-00003 TABLE 3 Ingredient Weight percentage range (% wt) C16-C18 SME 10-30 Disodium lauryl sulfosuccinate 5-20 Potassium lauryl sulfate 5-20 Cetyl alcohol 5-15 Lauric acid 5-15 Hydrogenated castor oil 1-10 Wheat starch 10-30 Glycerine 1-10 Titanium dioxide 0.1-0.5 Water to 100%

(28) Example 2 F-test and T-test for the Syndet Bar Formulation

(29) Statistical tests, including F-test and T-test, were conducted to assess the performance of the SME-based syndet bar composition. A SME syndet bar prepared based on the formulation of Table 1 was used as the test sample, in comparison to a commercially obtained syndet bar (which contains disodium lauryl sulfosuccinate as the main ingredient) and a combo soap (which contains sodium lauroyl isethionate as the main ingredient) Both the commercially obtained syndet bar and the combo bar do not contain SME. These test samples were assessed based on the soap performance parameters, including rinsability, smoothness, softening, lubricity and lather. In particular, all the subjects (i.e. the participants involved in the panel test) were required to fill in a questionnaire with all these performance parameters, and they were requested to evaluate the different samples in a quantitative manner. The comparison data of both F-test and T-test between the SME-based syndet bar and the commercial syndet bar are demonstrated in Table 4; while that between the SME-based syndet bar and the commercial combo bar are demonstrated in Table 5.

(30) TABLE-US-00004 TABLE 4 F-test T-Test Calculated Critical Result Calculated Critical Result Rinsability 1.179 1.984 Not 0.222 2.011 Not significant significant different different Smoothness 2.485 1.984 Significant 0.983 2.020 Not different significant different Softening 1.580 1.984 Not 2.019 2.011 Significant significant different different Lubricity 1.161 1.984 Not 1.106 2.011 Not significant significant different different Lather 1.104 1.984 Not 0.368 2.011 Not significant significant different different

(31) TABLE-US-00005 TABLE 5 F-test T-Test Calcu- Crit- Calcu- Crit- lated ical Result lated ical Result Rinsability 1.343 1.984 Not 0.789 2.011 Not significant significant different different Smoothness 0.818 0.504 Significant 0.718 2.011 Not different significant different Softening 1.011 1.984 Not 0.383 2.011 Not significant significant different different Lubricity 1.138 1.984 Not 0.870 2.011 Not significant significant different different Lather 1.126 1.984 Not 0.296 2.011 Not significant significant different different

(32) F-test focuses on the analysis of variance of the sample data while T-test refers to testing hypothesis of sample means to assess if the sets of samples are significantly different. Based on the test results shown in Tables 4 and 5, the SME-based syndet bar is demonstrated to perform as good as the commercially obtained combo soap, while providing improved softening effect as compared to the commercially obtained syndet bar. Such improvement in softening effect was shown to be significant by the T-test results.