CN1738895A - Soap/detergent bar composition and manufacturing process. - Google Patents

Abstract

The present invention provides a soap or detergent bar, primarily intended for personal or fabric washing. The bar has relatively low levels of total fatty matter, allowing relatively high levels of water and/or other liquid additives to be present. This is achieved whilst retaining good physical properties in the bar by incorporating aluminium hydroxide and tetra sodium pyrophosphate decahydrate into the bar. Methods of producing such bars are also disclosed.

Description

Soap bar/detergent bar composition and method of preparation

The present invention relates to a synergistic composition of soap/detergent bars, especially soap/detergent bars for body cleansing. It also relates to a process for the preparation of such personal and/or fabric washing soap/detergent bars. In particular, the present invention relates to a low total fat matter (TFM) soap/detergent bar containing high levels of water and other liquid builders and a method of making the same.

Common soap-based detergent bars used for body cleansing typically contain more than about 70 wt% TMF, with the balance being water (about 10-20%) and other components such as colors, fragrances, preservatives, and the like. Minor amounts of structurants and fillers are also present in the composition which replace a portion of the soap in the detergent bar while maintaining the desired hardness of the detergent bar. Known fillers include starch, kaolin and talc.

Non-milled hard soap bars with water content below 35% are also available. The TFM of these bars is about 30-65%. Reduction of TFM is usually achieved through the use of insoluble particulate matter and/or soluble silicates. Milled bars typically have a water content of about 8-15%, while non-milled hard bars have a water content of about 20-35%.

It is very important to be able to impart organoleptic properties such as lather and skin feel, preferably by adding builders to the composition of the bar without altering its processability and physical properties. Addition of other substances such as phosphates to the soap system can cause problems such as blooming, gritty feel and the like.

IN176384 discloses a detergent composition with low TFM content, by introducing up to 20% colloidal aluminum hydroxide (A-gel) so that the ratio of water to TFM in the composition is high without affecting the hardness of the soap bar , cleaning and foaming properties. The A-gel/TFM combination allows soap bars with higher water content to be prepared with lesser amounts of TFM. In this invention, although the maximum concentration of A-gel disclosed is up to 20 wt%, the examples of the invention are limited to the combination of 7.5 wt% A-gel with an additional structurant such as 5 wt% alkaline Silicates are used in combination with 40% TFM.

A method is disclosed in IN177828 wherein by the balanced use of aluminum hydroxide and TFM in combination it is possible to prepare soap bars with low TFM content, high water content and satisfactory hardness. This invention teaches that colloidal alumina can be formed in situ by the reaction of fatty acids/fats with an aluminum-containing basic substance, such as sodium aluminate, to form soap bars obtained by molding.

Our co-pending application 811/Bom/98 (corresponding to GB9906834.8) discloses that the use of A-gel at 9-16 wt% of the composition synergistically improves processability, sensory and physical properties of low TFM soap bars .

In addition, our co-pending application WO00/36075 discloses a method for the preparation of a low TFM soap bar with excellent properties, that is, the use of fatty acids and an aluminum-containing basic substance such as aluminum with a solid content of 20-55 wt% The reaction of sodium acid solution, wherein the weight ratio of aluminum oxide (Al ₂ O ₃ ) to sodium oxide (Na ₂ O) is 0.5-1.55. These bars have improved firmness and a smoother feel. The reaction can be carried out over a wide temperature range of 40-95°C.

Our application WO 01/42419 discloses a process for the preparation of low TFM soap bars with excellent properties comprising the in situ reaction of phosphoric acid with an aluminium-containing material such as sodium aluminate to form a mixture of aluminum hydroxide and orthophosphate. The solid phase content of the sodium aluminate solution is 20-55 wt%, and the weight ratio of aluminum oxide (Al ₂ O ₃ ) to sodium oxide (Na ₂ O) is 0.5-1.55. Soap bars prepared by this method have lower density and improved physical properties compared to soap bars filled with traditional raw materials such as calcite, kaolin and talc, without compromising their sensory properties. In this way, bars of soap can be formulated for use in both soft and hard water.

We have now found that tetrasodium pyrophosphate decahydrate (TSPP) can be An improved soap bar with a high water/TFM ratio and low TFM content is produced without compromising the hardness, cleansing and lathering performance of the bar. The reaction is preferably carried out in the presence of freshly formed soap to ensure good dispersion of the pyrophosphate formed in the soap mixture and thereby minimize particle size, with or without removal of the glycerol. If the soap is formed by reacting sodium aluminate with an oil mixture or fatty acid, the reaction to make TSPP is preferably carried out after the saponification stage is substantially complete.

Accordingly, a first aspect of the present invention includes a low total fatty matter toilet soap bar composition comprising 40-78% by weight total fatty matter, 0.4-13% by weight colloidal alumina gel (as Al ₂ O ₃ form), 0-23 wt% of TSPP in anhydrous salt form, 0-15 wt% glycerin and 7-30 wt% water (including water of hydration).

If the glycerin remains in the soap base, additional aluminate to neutralize the SAPP can be added during the saponification stage, and the excess aluminate can be neutralized with SAPP after the saponification reaction is complete.

The ratio of TSPP to alumina gel in the final formulation can vary within a certain range. To maximize the ratio of alumina, the sodium aluminate was neutralized with oil/fatty acid. In order to increase the proportion of TSPP, it is necessary to add SAPP, and SAPP should be neutralized with the necessary amount of alkali.

The weight ratio of _Al2O3 to _Na2O from the soap in the noodle after adjusting the water content is preferably in the range of 0.05:1 to 1.75: ₁ . The total content of free water and bound water is in the range of 7-30 wt%. Preferably the amount of TSSP in the anhydrous salt form in the composition is from 1 wt% to 20 wt%. If the glycerol formed during saponification is not removed, it will usually comprise 0-10 wt% in the final formulation. If the amount of glycerol produced by the saponification reaction is insufficient, additional glycerin can be added to bring it up to a certain level. The glycerin content of the final soap bar can be increased up to 15% by weight. Other additives commonly used in soap bars may also be added.

The process of the present invention can be carried out in any batch mixer commonly used in soap/detergent manufacture, and is preferably carried out in a high shear mixer. Preferred mixers include plowshare mixers, mixers with sigma, multi-friction overlap, single arc or double arm mixing elements. Dual-arm agitator mixers can be either overlapping or tangential. Alternatively, the invention can also be carried out as in conventional methods in conventional paddle mixers, helical screw agitator vessels or combinations of multi-head metering pumps/high shear mixers and spray dryers.

According to a second aspect of the present invention, a method of making a low total fatty matter detergent bar comprises the steps of:

a. Preparation of soap by reacting a mixture of one or more fats and/or fatty acids with an alkaline aluminum-containing substance and/or sodium hydroxide at a temperature of 60-150° C.;

b. optionally removing some or all of the glycerol from the soap mixture produced from (a), if desired;

c. If necessary, further reduce the TFM of pure soap by in-situ neutralization of alkaline aluminum-containing materials with SAPP;

d. Adjusting the moisture content of the soap base by adding or removing water from the soap mixture and cooling;

e. Converting the product of step (d) into soap bars.

In this context, the term total fatty matter, often abbreviated TFM, is used to denote the percentage by weight of fatty acid and triglyceride residues present in the composition, excluding associated cations.

For soaps having 18 carbon atoms, the associated sodium cations will generally amount to about 8 wt%. Other cations such as zinc, potassium, magnesium, alkylammonium and aluminum can be used as required.

The term soap denotes salts of carboxylic fatty acids. The soap may be derived from any triglyceride commonly used in the manufacture of soaps. Thus the carboxylate anion in the soap may contain from 8 to 22 carbon atoms.

Soaps can be obtained by saponification of fats and/or fatty acids. Fats or oils commonly used in soap making may be such as tallow, tallow stearin, palm oil, palm stearin, soybean oil, fish oil, castor oil, rice bran oil, sunflower oil, coconut oil, babassu oil, palm kernel oil etc.

In the above method, the fatty acid is derived from oil/fat selected from coconut, rice bran, groundnut, tallow, palm, palm kernel, cottonseed, soybean, castor and the like. The fatty acid soaps may also be prepared synthetically, for example by oxidation of petroleum or hydrogenation of carbon monoxide by Fischer-Tropsch reactions. Resin acids, such as those found in tall oil may also be used. Naphthenic acids are also suitable.

Tallow fatty acids can be derived from various animal sources and generally contain about 1-8% myristic acid, about 21-32% palmitic acid, about 14-31% stearic acid, about 0-4% palmitoleic acid , about 36-50% oleic acid and about 0-5% linoleic acid. A typical proportion is 2.5% myristic acid, 29% palmitic acid, 23% stearic acid, 2% palmitoleic acid, 41.5% oleic acid and 3% linoleic acid (all by weight percentage). Other similar mixtures such as those derived from palm oil and those derived from various tallows and lard are also included.

Coconut oil refers to an oil with a carbon chain length distribution of approximately 8% C ₈ , 7% C ₁₀ , 48% C ₁₂ , 17% C ₁₄ , 8% C ₁₆ , 2% C ₁₈ , 7% acid and 2% linoleic acid (the first six fatty acids listed are saturated). Other sources with similar carbon chain length distributions are included in the term coconut oil, such as palm nut oil and babassu kernel oil.

According to a preferred aspect of the present invention, up to 50 wt% of builders such as non-soap surfactants, skin care aids such as humectants, emollients, sunscreens or anti-aging compounds may be added at any step prior to milling. Alternatively some of these benefit ingredients may also be incorporated in bulk during compression molding.

A typical suitable fatty acid mixture consists of 5-30 wt% coconut fatty acid and 70-95 wt% fatty acid hardened rice bran oil. Fatty acids derived from other suitable oils/fats such as groundnut, soybean, tallow, palm, palm kernel, etc. may also be used in other desired proportions.

The non-soap surfactant may be an anionic surfactant, a nonionic surfactant, a cationic surfactant, an amphoteric surfactant or a zwitterionic surfactant or a mixture thereof. Examples of humectants and humectants include polyols, glycerin, cetyl alcohol, carbopol 934, ethoxylated castor oil, paraffin oil, lanolin and derivatives thereof. Silicone compounds such as silicone surfactants such as DC3225C (Dow Corning) and/or silicone emollients or silicone oils (DC-200 from Dow Corning) may also be included. Suitable sunscreens include 4-tert-butyl-4'-methoxydibenzoylmethane (trade name PARSOL 1789 from Givaudan) and/or 2-ethylhexyl methoxycinnamate (trade name PARSOLMCX , from Givaudan) or other UV-A and UV-B sunscreens.

Other additives may be added, such as one or more water-insoluble particulate materials, such as talc, kaolin, polysaccharides such as starch or modified starch, and cellulose.

Minor additives such as flavors, colorants, preservatives, fillers and other conventional additives can be added at any step of the process at 1-10 wt%.

The compositions of the present invention preferably contain a detersive active, generally selected from anionic and nonionic detersive actives.

Suitable anionic detergent-active compounds are water-soluble salts of organosulfurization reaction products having in their molecular structure an alkyl group having 8 to 22 carbon atoms and one selected from the group consisting of sulfonate groups Or free radicals of sulfate groups and mixtures thereof.

Examples of suitable anionic detergents are sodium and potassium alcohol sulfates, especially those obtained by sulfation of higher alcohols formed by reducing glycerides of animal oil or coconut oil; sodium alkylbenzene sulfonates and alkylbenzene Potassium sulfonates, such as those whose alkyl groups contain 9-15 carbon atoms; sodium alkyl glyceryl ether sulfates, especially those ethers of higher alcohols derived from animal oils and coconut oil; sodium coconut fatty acid monoglyceride sulfate; Sodium and potassium salts of sulfuric acid esters of reaction products of 1 mole of higher aliphatic alcohols and 3-6 moles of ethylene oxide; sodium salts of alkylphenol oxirane ether sulfates with 1-8 molecular units of ethylene oxide and Potassium salts in which the alkyl group contains 4-14 carbon atoms; reaction products of fatty acids esterified with isethionate and neutralized with sodium hydroxide, wherein the fatty acid is derived, for example, from coconut oil and mixtures thereof.

Preferred water-soluble artificial anionic detergent-active compounds are higher alkylbenzene sulfonic acids and mixtures thereof with olefin sulfonic acids and higher alkyl sulfuric acids, and alkali metal (such as sodium and potassium) salts of higher fatty acid monoglyceride sulfuric acid and alkaline earth metal (such as calcium and magnesium) salts.

Suitable nonionic detergent-active compounds can be broadly described as compounds formed by the condensation of an alkylene oxide which is hydrophilic in nature with an organic hydrophobic compound Can be aliphatic or alkylaromatic in nature. The length of the hydrophilic group or polyoxyalkylene radical condensed with any particular hydrophobic group is readily adjusted in order to produce a water-soluble compound with the desired degree of balance of hydrophilic and hydrophobic units.

Specific examples include condensation products of aliphatic alcohols having a linear or branched chain structure with 8-22 carbon atoms and ethylene oxide, such as coconut oil epoxy having 2-15 moles of ethylene oxide per mole of coconut alcohol. Condensates of ethane; condensation products of alkylphenols whose alkyl groups have 6-12 carbon atoms with 5-25 moles of ethylene oxide per mole of alkylphenol; reaction products of ethylenediamine with propylene oxide and epoxy Condensate of ethane, said condensate contains 40-80wt% of polyoxyethylene free radicals, molecular weight is 5000-11000; structure is R ₃ NO tertiary amine oxide, wherein one R group contains 8-18 Alkyl groups of carbon atoms and the other R groups are each methyl, ethyl or hydroxyethyl, such as dimethyl dodecyl amine oxide; tertiary phosphine oxides of the structure R ₃ PO in which one R group is An alkyl group containing 10-18 carbon atoms, while the other R groups are each an alkyl or hydroxyalkyl group containing 1-3 carbon atoms, such as dimethyldodecylphosphine oxide; and the structure _R2SO Dialkyl sulfoxides in which one R group is an alkyl group of 10 to 18 carbon atoms and the other R group is a methyl or ethyl group, such as methyltetradecyl sulfoxide; fatty acid alkyl alcohol amides ; Alkylene oxide condensates of fatty acid alkanolamides and alkylthiols.

Cationic, amphoteric or zwitterionic detergent actives may also be included in the compositions of the present invention.

Suitable cationic detergent actives that can be added are alkyl-substituted quaternary ammonium halide salts such as bis(hydrogenated tallow)dimethylammonium chloride, cetyltrimethylammonium bromide, benzene Formamide and laurylmethylpolyoxyethylene ammonium chloride and amine and imidazoline salts such as primary, secondary and tertiary amine hydrochlorides and imidazoline hydrochlorides.

Suitable amphoteric detergency-active compounds that may optionally be used are derivatives of aliphatic secondary and tertiary amines containing an alkyl group of 8 to 18 carbon atoms and an aliphatic group substituted by an anionic water-solubilizing group, such as Sodium 3-dodecylamino-propionate, sodium 3-dodecylaminopropanesulfonate, and sodium N-2-hydroxydodecyl-N-methyltaurate.

Suitable zwitterionic detergent-active compounds that may optionally be used are derivatives of aliphatic quaternary ammonium, sulfonium and phosphonium compounds having an aliphatic group of 8 to 18 carbon atoms and an aliphatic group substituted by a cationic water-solubilizing group. substances, such as 3-(N-N-dimethyl-N-hexadecylammonium)propane-1-sulfonate betaine, 3-(dodecylmethylsulfonium)propane-3-sulfonate betaine and 3-(hexadecylmethylphosphonium)ethanesulfonate betaine.

The invention will now be further described and for purposes of illustration only with reference to the following non-limiting examples which, inter alia, show a comparison of compositions prepared by the process described in the present invention with compositions not produced by a process not in accordance with the invention result.

Example 1.

Prepare 100 kg of soap base by first adding 4.73 kg of 90% active alpha-olefin sulfate (AOS), 0.85 kg of sodium chloride and 38.81 kg of 20.5 wt% Na ₂ O and 24.4 wt% _Al2O3 in _sodium aluminate solution. To this mixture was added 52.18 kg of molten distilled fatty acids (DFAs) at 90°C. The DFA's were saponified, then 0.12 kg of a 35 wt% sodium EDTA solution and 0.35 kg of a 60 wt% EHDP (etidronate) preservative solution were added and dispersed in the mixture. To this mixture was added an additional 6.11 kg of SAPP. This mixture is reacted with excess sodium aluminate to form TSPP. The water is consumed by evaporation of the heat released during the various reactions, and the final water content of the mixture is adjusted to yield 100 kg of soap base having the following composition:

wt% sodium soap 56.52 Sodium chloride 0.85 AOS 4.26 NaEDTA 0.04 EHDP 0.21 Al(OH) ₃ 14.48 TSPP10H ₂ O 12.28 free water 11.36 (4.06kg of water lost during treatment) total 100.0

To 93.9 kg of this soap base 5.0 kg of talc, 0.6 kg of fragrance and 0.5 kg of titanium dioxide were added and mixed in a zigzag mixer to obtain 100 kg of the final soap formulation. It is then ground, extruded and molded to form soap bars.

Examples 2a-d.

The following soap base is prepared by mixing approximately 100 kg of neat soap with glycerin, which is 0.5% salt in approximately 30% water and with the appropriate amount of SAPP slurried in a 2% saline solution at 80- Extracted at 90 degrees Celsius. To this mixture _was added sufficient sodium aluminate solution containing 20 wt% _Na2O and 20 wt% _Al2O3 at 70-90°C to completely neutralize the SAPP. The reaction between the aluminate solution and SAPP takes place in situ and the formed alumina gel and TSPP are completely dispersed throughout the soap. A dilute brine solution is added to this soap/alumina gel/TSPP mixture so that it can be pumped through a heat exchanger into a vacuum dryer for drying and then cooled to about 40°C before finally forming soap bars. In this way a complete series of soap bases of the following nominal compositions were prepared.

  2aA60 25wt% 2bA60 28wt%   2cA60 30wt% 2dA6043wt% sodium soap 81.3 73.8 67.2 60.3 Sodium chloride 0.5 0.5 0.5 0.5 NaEDTA 0.02 0.02 0.02 0.02 EHDP 0.02 0.02 0.02 0.02 Al(OH) ₃ 0.9 1.7 2.5 3.3 TSPP10H ₂ O 4.3 8.2 12.0 15.5 free water 13.0 15.8 17.8 20.4 total 100.0 100.0 100.0 100.0

Example 3.

20 kg of a mixture of 80 parts tallow/20 parts coconut oil preheated to 90 degrees Celsius was added to a plowshare mixer to prepare 40.33 kg of soap base. Add 14.8kg of sodium aluminate solution preheated to 90°C to this oil mixture, wherein the sodium aluminate solution contains 20wt% Na ₂ O and 20wt% Al ₂ O ₃ . The mixture is allowed to react with stirring until saponification of the triglycerides is substantially complete. To the clean soap mixture was added 2.1 kg of SAPP slurried in 3.4 kg of water at 85 degrees Celsius. Stirring was continued for 30 minutes to ensure complete neutralization of excess sodium aluminate after SAPP was saponified. Finally, 20 grams of a 40 wt% NaEDTA solution and 11 grams of a 60 wt% EHDP solution were added and stirring was continued for 5 minutes to ensure complete dispersion of the ingredients. A soap base of the following composition was obtained.

wt% soap 51.5 glycerin 5.8 Aluminum hydroxide 11.2 TSPP decahydrate 10.5 NaEDTA 0.019 EHDP 0.016 Water 21.0

Claims (10)

1. A soap bar composition with low total fatty matter, containing 40-78wt% of total fatty matter, 0.4-13wt% colloidal alumina gel (in the form of Al ₂ O ₃ ), 0-23wt% of TSPP in anhydrous salt form, 0-15 wt% glycerol and 7-30 wt% water including bound water. 2. A soap bar according to claim 1, wherein said composition additionally contains 5-50 wt% of a builder. 3. A soap bar according to claim 1 or 2, wherein said composition has an iodine value in the range of 35-75. 4. A soap bar according to any preceding claim, wherein said colloidal alumina gel is prepared from an aluminium-containing basic material. 5. A soap bar according to claim 4, wherein the aluminum- _containing alkaline substance is aluminum acid having a solids content of 20-55% by weight and a weight ratio of _Al2O3 to _Na2O of 0.5:1 to 1.55:1 sodium. 6. The soap bar of claim 5, wherein the aluminum-containing alkaline material is mixed with SAPP. 7. A method of preparing the low total fatty matter detergent bar described in any one of claims 1-6, comprising the steps of: a. Preparation of soap by reacting a mixture of one or more fats and/or fatty acids with an alkaline aluminum-containing substance and/or sodium hydroxide at a temperature of 60-150° C.; b. optionally removing some or all of the glycerol from the soap mixture produced from (a), if desired; c. If necessary, further reduce the TFM of pure soap by in-situ neutralization of alkaline aluminum-containing materials with SAPP; d. Adjusting the moisture content of the soap base by adding or removing water from the soap mixture and cooling; e. Converting the product of step (d) into soap bars. 8. The method of claim 7, wherein the aluminum-containing alkaline substance is sodium aluminate. 9. The method according to claim 7 or 8, wherein the solid content of the sodium aluminate is 20-55wt%. 10. A process according to _any one of claims 7-9, wherein the weight ratio of _Al2O3 to _Na2O in the soap after step (c) is in the range of 0.05:1 to 1.75:1.