RU2804321C2 - Bar compositions containing c10 soap with minimization of c18 unsaturated soap to caprate ratio - Google Patents

Abstract

FIELD: chemical products.

SUBSTANCE: composition of the bar of soap contains 25-85% (by weight of soap) C₈-C₂₄ fatty acids containing soap C₁₀ in the amount of 8% or 15% or more by weight of the entire composition of the bar and unsaturated C₁₈ soap, where the mass ratio of the said unsaturated C₁₈ soap to C₁₀ soap (caprate) is from 0.8 to 0.1, 1-45% organic and inorganic excipients by weight of the composition; 5-30% water by weight of the composition, where the excess of C₁₀ soap relative to the unsaturated C₁₈ soap is at least 6%, and the unsaturated C₁₈ fatty acid soap includes its hydroxy derivatives. Also disclosed is the use of the composition to impart antibacterial properties to a bar of soap.

EFFECT: enhanced rapid antibacterial activity.

5 cl, 9 tbl, 5 ex

Description

Field of technology to which the invention relates

The present invention relates to fatty acid soap bars that are typically produced by saponification (eg, neutralization) of a triglyceride oil containing fatty acid esters (bound to the glycerol backbone of the triglyceride oils) of varying chain lengths. It further relates to the use of novel combinations of minimum amounts of specific chain lengths (eg, C ₁₀ ) of soap-forming esters while minimizing others (including minimizing the amounts of chain lengths and/or level of saturation or unsaturation of certain esters fatty acids) to enhance antibacterial activity.

State of the art

Commercial soap bars typically contain one or more “soaps,” which, for purposes of describing this component of the soap bars of the present invention, have the meaning generally accepted in the art: monovalent salts of monocarboxylic fatty acids. As noted, they are usually formed by the saponification of triglyceride oils. Salt counterions typically include sodium, potassium, ammonium and alkanolammonium ions, but may include other suitable ions known in the art. The finished soap bars may also include optional auxiliary ingredients such as humectants, humectants, water, fillers, polymers, dyes, fragrances, and the like. to achieve cleansing and/or refreshment of the user's skin.

Typically, the soap components in conventional soap bars include long chain fatty acid salts having fatty acid alkyl groups with a chain length of from about 8 carbon atoms to 24 carbon atoms, preferably from 12 carbon atoms to about 18 carbon atoms. The particular length of alkyl chain(s) of soaps is selected for various reasons, including cleaning ability, foaming ability, cost, and the like. Soaps with shorter chains are known to be more water soluble (i.e. less hydrophobic) and produce more lather compared to soaps with longer chains. Longer chain soaps are often chosen for cost reasons and to provide structure to the soap bars.

To impart antibacterial properties to such conventional soap bars, germicides or antibacterial agents typically need to be added to the soap bars. For example, bars containing antimicrobial agents such as triclosan (ie 2,4,4'-trichloro-2'-hydroxy-diphenyl ether) and triclocarbanilide are known. However, adding antibacterial agents to soap bars to achieve antibacterial effectiveness may increase the cost of the soap bars due to the cost of the antibacterial agents themselves and the additional cost of manufacturing the soap bars.

Another way to enhance antimicrobial activity is to use a bar with a low total fat content (eg, in which the fatty acid soap is replaced by high levels of organic solvent and/or electrolyte).

WO 2017/016803 and WO 2017/016807 issued by Unilever disclose a cleaning bar containing 10-30% soap, 20-45% water-soluble organic solvent, 20-40% water and 3-20% electrolyte to form a bar with low total fatty matter content (Total Fatty Mater, TFM). WO 2017/016802, also issued by Unilever, shows the antimicrobial effect of this bar due to lower levels of soluble surfactant.

Many other references disclose bars of soap that contain wide-open amounts of capric acid soap (C ₁₀ soap) and/or unsaturated acid soaps such as oleate (eg, C ₁₈ with one unsaturated group in the cis configuration).

However, nowhere is there a relationship between maintaining certain minimum levels of C ₁₀ soap while minimizing the total level (of any chain length) of unsaturated soaps and minimizing the ratio of, in particular, unsaturated C ₁₈ soap to C ₁₀ soap.

The essence of the invention

Surprisingly, applicants have discovered that in fatty acid soap bars containing typically 25-85%, preferably 30-75% fatty acid soap, the amount of caprate (C ₁₀ soap) is 7-32% or 8-32%, or between 9% or 10% to 32%, or from 11% or 12%, or 13%, or 14%, or 15% to 32%, or 16-32% by weight of the entire composition of the bar. The upper limit can be 31%, 30%, 29%, 28% or 25%. The above upper and lower ranges can be used interchangeably. The preferred range is 8-24% by weight of the composition; and, further, when at the same time the level of unsaturated C ₁₈ fatty acid soaps, in particular oleate (but may include C ₁₈ with one or more unsaturated groups) is limited such that the ratio of unsaturated C ₁₈ to C ₁₀ fatty acid soap (caprate) maintained at a level preferably 1.2 and below (up to 0.2, or 0.1, or 0%), more preferably 1.1 or below, or 1.05 and below, or 1.0 and below, or 0, 80 and below, more preferably 0.55 and below and even more preferably 0.30 and below (for example, the ratio of oleate to caprate soap is 0:0.30); then the antibacterial activity of this bar composition is significantly increased compared to, for example, a bar where the ratio is higher, for example equal to 1.35.

It is noted that the more soap present, the more effective the destruction occurs at the same ratio. For example, a bar containing 60 wt.% soap and a 1:1 ratio is more effective than a bar containing 40 wt.% soap and the same ratio of unsaturated C ₁₈ soap to caprate.

A preferred bar contains 8-28% or 8-24% caprate by weight of the composition and a ratio of unsaturated C ₁₈ fatty acid soap to caprate of 1.1:0 or 1.05:0 or 1.0:0. It is preferable to have an excess of caprate to the unsaturated C ₁₈ fatty acid soap. In the bars of the invention, the excess of caprate relative to the C ₁₈ unsaturated acid is at least 6%, sometimes 10% or more, or 14% or more.

The soap counterion may be an alkali metal such as sodium or potassium, or may be, for example, an alkanolamine such as triethanolamine.

Unsaturated C ₁₈ fatty acid soaps may have one, two or three unsaturated groups and mixtures thereof. They also include hydroxy derivatives of unsaturated C ₁₈ soap, such as hydroxyoleate, and ricinoleic acid soaps. Generally, _C18 oleate soap (one unsaturated group) is the most predominant _C18 soap, but _C18 soap may also include elaidic acid soap ( _C18 soap with one unsaturated group in this configuration) or _C18 fatty acid soap with more than one unsaturated bond (for example, linoleic, alpha-linoleic). Preferably, the level of C ₁₈ fatty acid with three unsaturated groups is less than 0.2%, more preferably less than 0.1%.

Disclosure of the Invention

The present invention relates to fatty acid soap bars (e.g., bars containing 25-85% by weight of fatty acid soap) in which C ₁₀ soap makes up 8-32% of the bar as above, and the ratio of unsaturated C ₁₈ soap to soap C ₁₀ is 1.2:0.1 or 1.1:0.1, preferably 1.05:0.1, as also stated above.

More specifically, the invention relates to a soap bar composition comprising:

a) 25-85%, preferably 35-75% by weight of C ₈ -C ₂₄ fatty acid soap containing:

(i) C ₁₀ soap in an amount of 8% or 15%, or more, more preferably 16-32% by weight of the total bar composition; And

(ii) unsaturated C ₁₈ soap, where the ratio of said unsaturated C ₁₈ soap to C ₁₀ soap (caprate) is 1.2 to 0.1,

b) 1-45% organic and inorganic excipients by weight of the composition; And

c) 5-30%, preferably 13-28% water by weight of the composition.

More specifically, the invention relates to a soap bar composition comprising:

a) 25-85% by weight, preferably 28-76% soap C ₈ -C ₂₄ fatty acids;

Where:

(i) C ₁₀ soap makes up 8% or 9% or 10% or 15% or more, more preferably 16-32% by weight of the total bar composition;

(ii) the level of unsaturated soap _C18 (preferably with 1, 2 or 3 unsaturated groups), including molecules of unsaturated _C18 acid with hydroxy or other derivative (for example, hydroxyoleic acid) and mixtures thereof, is such that the ratio of unsaturated soap C ₁₈ to soap C ₁₀ (caprate) is 1.2 or 1.1 or 1.05 or 0.80 or 0.55 or 0.30;

b) 1-45% by weight, preferably 2-45% by weight of organic and inorganic auxiliary substances; And

c) 5-30%, preferably 13-28% by weight of water.

It should be noted that those skilled in the art have no reason to maintain C ₁₀ fatty acid soap levels high (eg, to maintain a low ratio of unsaturated C ₁₈ soap to C ₁₀ fatty acid soap), and therefore such increased quantities are not supplied. Elevated amounts of C ₁₀ fatty acid soap are also not found in nature. In nut oil, for example, C ₁₀ soap is present in maximum quantities of 6-7 wt.%.

More specifically, the bars of the invention contain a base consisting of 25-85% by weight of C ₈ -C ₂₄ fatty acid soap. Fatty acid soaps and any other surfactants that may additionally be present must be suitable for normal contact with human skin.

The term "soap" is used herein in its generally accepted sense, i.e. denotes alkali metal salts or alkanolammonium salts of aliphatic alkane or alkene monocarboxylic acids. For the purposes of the present invention, the most suitable cations are sodium, potassium, magnesium, mono-, di- and triethanol ammonium or combinations thereof. In general, sodium soaps are used in the compositions of the present invention, but up to about 15% of the soap may be potassium, magnesium, or triethanolamine soaps. The soaps used in the present invention are well-known alkali metal salts of natural or synthetic aliphatic (alkanoic or alkenoic) acids having from about 8 to about 24 carbon atoms. They can be described as alkali metal carboxylates of saturated or unsaturated hydrocarbons containing from about 8 to about 24 carbon atoms.

Fatty acid soaps are derived from fatty acids, which can be a variety of fatty acids, typically fatty acids containing fatty acid moieties with chains ranging from C ₈ to C _{24 in} length. Subject to certain requirements of having at least a certain amount of C ₁₀ , maintaining a certain ratio of oleate to C ₁₀ , minimizing unsaturated C ₁₈ other than oleate, and maintaining a certain molar ratio of C ₁₀ soap to unsaturated fatty acid soap, a mixture of fatty acids can contain certain amounts of relatively pure one or more fatty acids. Suitable fatty acids include, but are not limited to, butyric, caproic, caprylic, capric, lauric, myristic, myristeloid, pentadenanoic, palmitic, palmitoleic, margaric, heptadecenic, stearic, oleic, linoleic, linolenic, arachidonic, gaoleic, behenic and lignoceric acids and their isomers. In some preferred forms, the fatty acid mixture has low levels of fatty acid content with a saturated fatty acid moiety having a chain length of 14 carbon atoms (myristic acid).

In general, the chain length of fatty acid soaps varies depending on the original raw fat or oil (for the purposes of this description, the terms “oil” and “fat” are used interchangeably unless the context otherwise requires). Longer chain fatty acid soaps (e.g. _C16 palmitic or _C18 stearic acid) are usually obtained from tall and palm oils, while shorter chain fatty acid soaps (e.g. _C12 lauric acid) can generally be obtained from e.g. from coconut oil or palm kernel oil. The resulting fatty acid soaps may also be saturated or unsaturated (eg oleic acid) according to the requirements of the invention.

In general, fatty acid soaps with higher molecular weights (such as C ₁₄ to C ₂₂ soaps), especially longer saturated soaps, are insoluble and do not form good volumes of lather, although they can give the lather that other soluble soaps form more body. and sustainability. In contrast, lower molecular weight soaps (eg, _C8 to _C12 ) and unsaturated soaps (eg, oleic acid) lather quickly. However, soaps with longer chain acids (usually saturated, although they may also contain some level of unsaturated, such as oleic) are desirable because they maintain the structure of the soap and do not dissolve as easily. Unsaturated soaps (such as oleic soaps) are soluble and foam quickly, like short-chain acid soaps, but produce a denser, thick lather like longer-chain acid soaps.

Source soaps typically do not contain C ₁₀ fatty acid materials at levels of 7% and above, especially 8% and above (eg, palm kernel oils (PKO), coconut oils). These levels of C ₁₀ soap below 7% by weight are below the preferred levels in the bars of the invention. Bars, for example, having a total fat content of 76%, contain a maximum of 4% C ₁₀ fatty acid soap. In typical commercial bars, which are a 70/30 PKO/coconut oil blend, this level can be as low as 1.7%. Moreover, _C18 soap levels are typically around 30%, which is much higher than _C10 soap levels. In the absence of knowledge about the benefits of high _C10 and low _C18 soap (eg, low ratio of unsaturated _C18 to _C10 ), there is no basis for making such bars. This has the advantage of achieving a rapid antibacterial effect at room temperature, and to the best of the applicants' knowledge, this advantage is not recognized by those skilled in the art. Thus, there is no reason to select or develop such a parent soap.

It should be noted that, in general, saturated fatty acid soaps with higher molecular weights (e.g. C ₁₄ -C ₂₂ soaps) are insoluble and do not produce good volumes of lather, although they may help make the lather produced by other soluble soaps more thick and stable.

Auxiliary organic and inorganic substances

The total content of excipients used in the bar composition should be no more than 50%, preferably 1 to 50%, more preferably 1 to 45%, even more preferably 3 to 45% by weight of the soap bar composition.

Suitable starch materials that can be used include natural starch (starch from corn, wheat, rice, potato, tapioca, etc.), pregelatinized starch, various physically and chemically modified starches, and mixtures thereof. The term "natural starch" refers to starch that has not been chemically or physically modified, also known as raw or native starch.

The preferred starch is natural or native starch from corn (maize), cassava, wheat, potato, rice and starch from other natural sources. Crude starch with varying ratios of amylose and amylopectin, such as from corn (25% amylose); waxy maize (0%); corn with high amylose content (70%); potatoes (23%); rice (16%); sago (27%); cassava (18%); wheat (30%) and others. The raw starch may be used directly or modified during the manufacture of the bar composition such that the starch is either partially gelatinized or fully gelatinized.

Another suitable starch is pre-gelatinized starch, that is, starch that has been gelatinized before being added as an ingredient in the bar composition of the present invention. Various forms are available that thicken at different temperatures, such as starch, which is able to disperse in cold water. One suitable commercial pregelatinized starch is available from National Starch Co. (Brazil) under the trade name FARMAL® CS 3400, but other commercially available substances with similar properties are suitable.

Polyol

The other organic auxiliary compound may be a polyol or a mixture of polyols. The term "polyol" is used herein to mean a compound that contains multiple hydroxyl groups (at least two, preferably at least three) and is highly soluble in water, preferably readily soluble in water.

Many types of polyols are available, including relatively low molecular weight, short chain polyhydroxy compounds such as glycerol and propylene glycol; sugars such as sorbitol, mannitol, sucrose and glucose; modified carbohydrates such as hydrolyzed starch, dextrin and maltodextrin; and polymeric synthetic polyols such as polyalkylene glycols, for example polyoxyethylene glycol (PEG) and polyoxypropylene glycol (PPG).

Particularly preferred polyols are glycerin, sorbitol and mixtures thereof.

The level of polyol content can be important to form a thermoplastic mass whose properties are suitable for both high production (300-400 bars per minute) and for use as a personal wash bar. For example, when the polyol content is too low, the mass may not be sufficiently malleable at the extrusion temperature (eg, 40° C. to 45° C.), and the bars become excessively mushy and fray quickly. Conversely, when the level of polyols is too high, the mass becomes too soft to be formed into bars at high speed during production at normal temperatures.

In a preferred embodiment, the bars of the invention contain 0-35%, preferably 0.5-15% by weight of polyol. As noted, preferred polyols include glycerol, sorbitol, and mixtures thereof.

The adjuvant system may optionally include insoluble particles containing a single substance or a combination of substances. Insoluble particles refer to substances that are in the form of solid particles and are suitable for personal washing. Preferably, mineral (eg inorganic) or organic particles are present.

Insoluble particles should not feel coarse or granular, and therefore should have a size of less than 300 microns, more preferably less than 100 microns, and most preferably less than 50 microns.

Preferred particulate inorganic material includes talc and calcium carbonate. Talc is a mineral magnesium silicate that has a layered silicate structure, the composition Mg ₃ Si ₄ (OH) ₂₂ , and can be found in hydrated form. It has a lamellar morphology and is largely oleophilic/hydrophobic, meaning it is better wetted by oil than by water.

Calcium carbonate or chalk exists in three crystalline forms: calcite, aragonite and vaterite. The natural morphology of calcite is rhombohedral or cuboid, acicular or dendritic for aragonite, and spheroidal for vaterite.

Industrially, calcium carbonate or chalk, known as precipitated calcium carbonate, is produced by the carbonization method in which carbon dioxide gas is bubbled through an aqueous suspension of calcium hydroxide. The calcium carbonate obtained in this method is of the crystalline calcite type or is a mixture of calcite and aragonite.

Examples of other optional insoluble inorganic particulate materials include aluminosilicates, aluminates, silicates, phosphates, insoluble sulfates, borates and clays (eg, kaolin, china clay) and combinations thereof.

Particulate organic materials include insoluble polysaccharides such as highly cross-linked or insoluble starch (eg, produced by reaction with a hydrophobic agent such as octyl succinate), and celluloses; synthetic polymers, such as various polymer matrices and polymer suspensions; insoluble soaps and their mixtures.

The bar compositions preferably contain 0.1-25% by weight of the bar composition, preferably 5-15% by weight of these mineral or organic particles.

Water

The bars according to the invention contain 5-30% by weight, preferably 13-28% by weight of water.

Optional Ingredients

Synthetic Surfactants: Bar compositions may optionally include non-soap synthetic surfactants (detergents) - so-called syndets. Syndets may include anionic surfactants, nonionic surfactants, amphoteric or zwitterionic surfactants, and cationic surfactants.

The content of synthetic surfactant present in the bar is typically less than 25%, preferably less than 15%, preferably up to 10%, and most preferably 0 to 7% by weight of the total weight of the bar composition.

The anionic surfactant may be, for example, an aliphatic sulfonate such as a primary alkanesulfonate (eg, C ₈ -C ₂₂ ), primary alkanesulfonate (eg, C ₈ -C ₂₂ ), C ₈ -C ₂₂ alkene sulfonate, C ₈ -C ₂₂ hydroxyalkane sulfonate or alkyl glyceryl ether sulfonate (AGS); or an aromatic sulfonate such as an alkyl benzene sulfonate. Alpha-olefin sulfonates are other suitable anionic surfactants.

The anionic agent may also be an alkyl sulfate (eg, a C ₁₂ -C ₁₈ alkyl sulfate), particularly a primary alcohol sulfate or an alkyl ether sulfate (including alkyl glyceryl ether sulfates). The anionic surfactant may also be a sulfonated fatty acid such as alpha-sulfonated tallow fatty acid, a sulfonated fatty acid ester such as alpha-sulfonated methyl talloate, or mixtures thereof.

The anionic surfactant may also be alkyl sulfosuccinates (including mono- and dialkyl, eg C ₆ -C ₂₂ sulfosuccinates); alkyl and acyl taurates, alkyl and acyl sarcosinates, sulfoacetates, C ₈ -C ₂₂ alkyl phosphates and phosphates, alkyl phosphate esters and alkoxylalkyl phosphate esters, acyl lactates or lactylates, C ₈ -C ₂₂ monoalkyl succinates and maleathionates, sulfoacethionates and acyl ethionates.

Another class of anionic compounds are C ₈ -C ₂₀ alkyl ethoxy (1-20 EO) carboxylates.

Other suitable anionic surfactants are C ₈ -C ₁₈ acyl isethionates. These esters are prepared by reacting an alkali metal isethionate with mixed aliphatic fatty acids containing from 6 to 18 carbon atoms and having an iodine number of less than 20. At least 75% of the mixed fatty acids contain from 12 to 18 carbon atoms and up to 25% contain from 6 to 10 carbon atoms. The acyl isethionate may also be alkoxylated isethionates.

Acyl isethionates, if present, are typically present in the range of from about 0.5% to about 25% by weight of the total composition.

Typically, the anionic component makes up the majority of the synthetic surfactants used in the bar composition.

Amphoteric detergents that can be used in the present invention include at least one acidic group. This may be a carboxylic or sulfonic acid group. They contain quaternary nitrogen and are therefore quaternary acid amides. Typically they should include an alkyl or alkenyl group containing 7-18 carbon atoms. Suitable amphoteric surfactants include amphoacetates, alkyl and alkylamidobetaines, and alkyl and alkylamidosulfobetaines.

Amphoacetates and diamphoacetates are also included as possible zwitterionic and/or amphoteric compounds that may be used.

Suitable nonionic surfactants include the reaction products of compounds having a hydrophobic group and a reactive hydrogen atom, for example aliphatic alcohols or fatty acids, with alkylene oxides, in particular with ethylene oxide alone or together with propylene oxide. Examples include condensation products of aliphatic (C ₈ -C ₁₈ ) primary or secondary linear or branched alcohols with ethylene oxide and products obtained by condensation of ethylene oxide with the reaction products of propylene oxide and ethylenediamine. Other so-called nonionic detergent compounds include long-chain tertiary amine oxides, long-chain tertiary phosphine oxides, and dialkyl sulfoxides.

Sugar amides, such as alkyl polysaccharides and alkyl polysaccharide amides, can also be nonionic.

Examples of cationic detergents are quaternary ammonium compounds such as alkyldimethylammonium halides.

Other surfactants that may be used are described in US Pat. No. 3,723,325 to Parran Jr. and "Surface Active Agents and Detergents" (Vol. I & II) by Schwartz, Perry & Berch, both of which are also incorporated herein by reference.

Final excipients

These ingredients either directly (fragrance) or indirectly (preservatives) improve the aesthetic qualities of the bar, in particular visual, tactile and olfactory characteristics. A wide variety of optional ingredients may be included in the bar composition of the present invention. Examples of excipients include, but are not limited to: fragrances; opalescent components such as fatty alcohols, ethoxylated fatty acids, solid esters and TiO ₂ ; dyes and pigments; pearlescent additive, for example, TiO ₂ -coated mica, and other pearlescent pigments; plate-like mirror particles such as organic glitter; sensory substances such as menthol and ginger; preservatives such as dimethyloldimethylhydantoin (Glydant XL1000), parabens, sorbic acid, etc.; antioxidants such as, for example, butyl hydroxytoluene (BHT); chelating agents such as ethylenediaminetetraacetic acid (EDTA) salts and trisodium etridronate; emulsion stabilizers; auxiliary thickeners; buffering agents; and mixtures thereof.

The pearlescent additive content should be from about 0.1% to about 3%, preferably from 0.1% to 0.5%, and most preferably from about 0.2 to about 0.4%, based on the total weight of the bar composition.

Skin Beneficial Agents

A special class of optional ingredients emphasized herein are skin benefit agents, which are added to improve the health and condition of the skin and hair. Potential beneficial agents include, but are not limited to: lipids such as cholesterol, ceramides and pseudoceramides; antimicrobial agents such as triclosan; sunscreen agents such as cinnamates; other types of exfoliating particles such as polyethylene beads, walnut shells, apricot seeds, flower petals and seeds, and inorganic substances such as silica and pumice; additional emollients (skin softening agents) such as long chain alcohols and waxes such as lanolin; additional humidifiers; skin tonic agents; skin nutrients such as vitamins such as vitamins C, D and E, and essential oils such as bergamot, katsuma, calamus, etc.; water-soluble or insoluble extracts of avocado, grapes, grape seeds, myrtle, cucumber, watercress, calendula, elderberry, geranium, linden blossom, amaranth, seaweed, ginkgo, ginseng, carrot; balsam, camu camu, alpine leaf and other plant extracts such as witch hazel, and mixtures thereof.

The composition may also include a variety of other active ingredients that provide additional beneficial effects on the skin (including the scalp). Examples include anti-acne agents such as salicylic acid and resorcinol; sulfur-containing D- and L-amino acids and their derivatives and salts, in particular their N-acetyl derivatives; active substances against wrinkles, skin atrophy and for skin restoration, such as vitamins (for example A, E and K), vitamin alkyl esters, minerals, magnesium, calcium, copper, zinc and other metal components; retinoic acid and its esters and derivatives, such as retinal and retinol, vitamin B3 compounds, alpha hydroxy acids, beta hydroxy acids, for example salicylic acid and its derivatives; skin soothing agents such as aloe vera, jojoba oil, propionic and acetic acid derivatives, phenamic acid derivatives; artificial tanning agents such as dihydroxyacetone; tyrosine; tyrosine esters such as ethyl tyrosinate and glucose tyrosinate; skin lightening agents such as aloe extract and niacinamide, alpha-glyceryl-L-ascorbic acid, aminothyroxine, ammonium lactate, glycolic acid, hydroquinone, 4-hydroxyanisole, sebaceous gland stimulating agents such as brionolic acid, dehydroepiandrosterone (DHEA) and orizano; sebaceous suppressants such as aluminum hydroxychloride, corticosteroids, dehydroacetic acid and its salts, dichlorophenyl imidazole dioxolane (supplied by Elubiol); antioxidants, protease inhibitors; skin lifting agents such as ternary copolymers of vinylpyrrolidone, (meth)acrylic acid and a hydrophobic monomer consisting of long chain alkyl (meth)acrylates; anti-itch agents such as hydrocortisone, methdilysine and trimeprazine, a hair growth inhibitor; 5-alpha reductase inhibitors; agents that increase desquamation; anti-glycation agents; anti-dandruff agents such as zinc pyridinthione; hair growth stimulants such as finasteride, minoxidil, vitamin D and retinoic acid analogues and mixtures thereof.

Electrolyte

Soap bars contain 0.5-5 wt.% electrolyte. Preferred electrolytes include alkali metal or alkaline earth metal chlorides, sulfates and phosphates. Without being bound by any theory, it is believed that electrolytes contribute to the structuring of the solidified soap mass, and also increase the viscosity of the molten mass due to the general ionic effect. The soap bars used for comparison, which did not contain any electrolyte, were found to be milder. Sodium chloride and sodium sulfate are the most preferred electrolytes, and their content is preferably from 0.6 to 3.6 mass% and most preferably from 1.0 to 3.6 mass%.

Polymers

The soap bars may include from 0.1 to 5% by weight of a polymer selected from acrylates or cellulose ethers. Preferred acrylates include cross-linked acrylates, polyacrylic acids or sodium polyacrylates. Preferred cellulose ethers include carboxymethylcelluloses or hydroxyalkylcelluloses. It is also possible to use a combination of these polymers, provided that the total amount of polymers does not exceed 5 wt.%.

Acrylates

Preferred bars contain from 0.1 to 5% acrylates. More preferred bars contain from 0.15 to 3% acrylates. Examples of acrylate polymers include polymers and copolymers of acrylic acid cross-linked with polyallyl sucrose, as described in US Pat. No. 2,798,053, which is incorporated herein by reference. Other examples include polyacrylates, acrylate copolymers or alkali-swellable emulsions of acrylate copolymers (eg, ACULYN ^® 33, which is manufactured by Rohm and Haas; CARBOPOL ^® Aqua SF-1, which is manufactured by Lubrizol Inc.), hydrophobically modified alkali-swellable copolymers ( for example, ACULYN ^® 22, ACULYN ^® 28 and ACULYN ^® 38, which are manufactured by Rohm and Haas). Commercially available crosslinked acrylic acid homopolymers include CARBOPOL® 934, 940, 941, 956, 980 and 996 carbomers, which are available from Lubrizol Inc. Other commercially available crosslinked acrylic acid copolymers include the CARBOPOL ^® Ultrez series (Ultrez ^® 10, 20 and 21) and ETD series (ETD 2020 and 2050) copolymers available from Lubrizol Inc.

CARBOPOL® Aqua SF-1 is the most preferred acrylate. The compound is a slightly cross-linked, alkali-swellable acrylate copolymer that has three structural units; one or more carboxylic acid monomers having from 3 to 10 carbon atoms, one or more vinyl monomers and one or more mono- or polyunsaturated monomers.

Cellulose ethers

Preferred bars include from 0.1 to 5% cellulose ethers. More preferred bars contain from 0.1 to 3% cellulose ethers. Preferred cellulose ethers are selected from alkylcelluloses, hydroxyalkylcelluloses and carboxyalkylcelluloses. More preferred bars contain hydroxyalkyl celluloses or carboxyalkyl celluloses, and most preferred bars contain carboxyalkyl cellulose.

Preferred hydroxyalkylcellulose includes hydroxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose and ethylhydroxyethylcellulose.

Preferred carboxyalkylcellulose includes carboxymethylcellulose. Most preferably, carboxymethylcellulose is contained in the form of carboxymethylcellulose sodium salt.

Wax and polyalkylene glycols

Preferred waxes include paraffin wax and microcrystalline wax. If polyalkylene glycols are used, preferred bars may include from 0.01 to 5 wt% polyalkylene glycols, more preferably from 0.03 to 3 wt% and most preferably from 0.5 to 1 wt%. Suitable examples include polyethylene glycol and polypropylene glycol. The preferred commercial product is POLYOX®, available from The Dow Chemical Company.

A preferred composition of the present invention contains (by weight):

1) 25-85% soap, preferably sodium soap;

2) 0-35% polyol, preferably glycerol, sorbitol or a mixture;

3) 0-25% particles; And

4) 10-30% water.

PROTOCOLS

IN-VITRO ANTIMICROBIAL ACTIVITY ASSESSMENT PROTOCOL

Preparation of soap suspension

The bar of soap to be evaluated was grated into small pieces using a fine cheese grater. The soap bar pieces were mixed with water at a concentration of 10 wt.% and stirred on a magnetic stirrer overnight at 25°C. It is important to size the stirrer rod to maintain turbulence throughout the stirring volume. A homogeneous gel-like soap suspension was prepared and used freshly for in vitro microbial killing assays over time.

Bacteria

Escherichia coli ATCC 10536 was obtained as a lyophilized culture from the American Type Culture Collection. Fresh test cultures were grown twice for 24 hours on tryptic soy agar (TSA) streak plates at 37.0°C before each experiment. An E. coli suspension was then prepared with tryptone soy agar supplemented with sodium chloride immediately prior to potency tests.

In vitro analysis of the destruction of microorganisms over time (time-kill assay)

Time-kill assays were carried out at 25°C in accordance with the European standard EN 1040:2005 entitled “Chemical disinfectants and antiseptics - Quantitative suspension test for assessing the bactericidal activity of chemical disinfectants and antiseptics - Method and requirements trial (phase 1),” incorporated herein by reference. Following this procedure, bacterial cultures in the growth phase at a concentration of 1.5 × 10 ⁸ to 5 × 10 ⁸ colony forming units per ml (CFU/ml) were treated with soap solutions (prepared as described above) at 25°C. When forming the test sample, 8 parts by weight of the soap solution prepared as described above were combined with 1 part by weight of the culture and 1 part by weight of water. After 10, 20 and 30 seconds of exposure, the samples were neutralized to stop the antibacterial activity of the soap solutions. The test solutions were then serially diluted, plated on solid medium, incubated for 24 hours, and the number of surviving cells was counted. Bactericidal activity was determined as the logarithm of the reduction in CFU/ml calculated relative to the bacterial concentration at time 0 seconds. Cultures not exposed to any soap solutions served as untreated controls.

The _log10 reduction was calculated using the formula:

Decrease Log ₁₀ = log ₁₀ (number of controls) - log ₁₀ (survivors in tested samples)

Substrate Wash Solution Analysis

To determine the effectiveness of the bar formulation in removing bacteria from substrates, in vitro efficacy tests were performed on artificial skin samples (VITRO-SKIN™, IMS Corp., a synthetic substrate designed to mimic the surface chemistry of human skin). To prepare the substrate, VITRO-SKIN pieces were hydrated overnight in a hydration chamber with a reservoir containing 85% water and 15% glycerol. After approximately 24 hours, the VITRO-SKIN pieces were removed from the chamber and left for one hour at ambient temperature and humidity, and then 5 cm diameter circular sections were mounted between opposite sides of the XRF cup.

Each VITRO-SKIN piece used was uniformly inoculated with 1.5 x 10 ⁸ - 5 x 10 ⁸ CFU of E. coli using 100 µl of the culture obtained after overnight growth as described above. The bacteria were left to dry on the VITRO-SKIN for 30 minutes.

To simulate skin washing, the soap bar composition was cut into a 1 cm diameter cylinder and the bar was soaked in deionized water. After wetting the VITRO-SKIN with 0.7 mL of water, the soap bar composition was gently rubbed over the entire surface of the VITRO-SKIN inside the XRF cup for 15 seconds. Foam was then generated by continuously rubbing the VITRO-SKIN with a Teflon bar for 45 seconds (eg, in the absence of a soap bar composition). The wash liquid was removed and the VITRO-SKIN was rinsed by adding 10 ml deionized water to the XRF cup and wiping the substrate with a clean Teflon rod for 30 seconds. The rinsing step was repeated one more time.

After removing the wash liquid, 10 mL of ice-cold D/E broth was immediately added to each XRF dish. The dishes were tightly sealed with Teflon and shaken vigorously for 1 min to remove bacteria. Serial dilutions of the liquids were made and plated for colony counts on tryptic soy agar for 24 hours at 37°C. CFU/ml were then counted and calculated, and the results were expressed as log ₁₀ CFU. A lower log ₁₀ value (CFU/ml) corresponds to a greater efficiency of the bar in removing bacteria from the substrate.

Examples

The following examples further describe and demonstrate embodiments within the scope of the invention. The examples are given for illustrative purposes only and should not be construed as limitations, since many variations are possible without departing from the spirit and scope of the invention.

Table 1:

The effectiveness of the destruction of microorganisms over time (Time-Kill) depending on the ratio of unsaturated C ₁₈ soap (for example, oleate) to Na caprate.

In the mixture, Na caprate is maintained at a fixed level, simulating a bar of soap containing 16 wt.% Na caprate, as well as Na soap C ₁₈ varying in the range from 0 to 22 wt.%.

Table 1

Mass ratio Na
unsaturated salt C ₁₈ /caprate Na Nominal wt.% Na caprate in simulated bar Nominal wt% Na C ₁₈
in an imitation bar Log ₁₀ reduction against E.coli ATCC 10536 at 30 sec contact time Example 1 0.00 16.4 0 3.3 ± 0.2 Example 2 0.26 16.4 4.3 3.4 ± 0.2 Example 3 0.52 16.4 8.6 2.6 ± 0.1 Example 4 0.79 16.4 12.9 1.4 ± 0.1 Example 5 1.05 16.4 17.2 1.2 ± 0.1 Comparative Example A 1.31 16.4 21.5 0.9 ± 0.1 Comparative Example B To infinity 0 16.5 0.1±0.1

As shown in Table 1, Na soap of the unsaturated C ₁₈ fatty acid begins to inhibit the biocidal effectiveness of Na caprate (we defined it as a log ₁₀ reduction against E. coli ATCC 10536 of at least 1.0, preferably at least 1 ,2, more preferably at least 1.4), when the ratio of unsaturated C ₁₈ soap to caprate is below 1.2. When the ratio of Na unsaturated C ₁₈ soap to Na caprate increases to a value above 1.3, Na caprate loses almost all of its biocidal effectiveness. The test solution contains Na caprate at a fixed concentration of 1.64 wt.%, simulating the content in the bar of 16.4 wt.%, as well as Na soap of unsaturated C ₁₈ at a concentration in the range of 0-2.15 wt.%, simulating the content in the bar in the range of 0-17.2 wt.%. As noted, C ₁₀ soap can be as low as 7% by weight, provided the ratio of unsaturated C ₁₈ to C ₁₀ is 1.2 or lower.

table 2

Comparison of the effect of short-chain soaps between C10 and C14 on antimicrobial effectiveness (holding constant long-chain saturated soaps and unsaturated soaps).

Ingredients (wt.%) Comparative Example C Example 6 Comparative Example D Comparative Example E Sodium caprylate 25.64 / / / Sodium caprate / 25.64 / / Sodium laurate / / 25.64 / Sodium myristate / / / 25.64 Sodium palmitate 10.52 10.52 10.52 10.52 Sodium stearate 13.76 13.76 13.76 13.76 Sodium oleate 26.63 26.63 26.63 26.63 Sodium linoleate 3.97 3.97 3.97 3.97 Sodium linolenate 0.28 0.28 0.28 0.28 Sodium chloride 0.72 0.72 0.72 0.72 EDTA 0.04 0.04 0.04 0.04 EHDP 0.02 0.02 0.02 0.02 Tinopal CBS-X 0.024 0.024 0.024 0.024 Palm kernel oil fatty acid 0.50 0.50 0.50 0.50 Flavoring additive 1.25 1.25 1.25 1.25 Water 16.63 16.63 16.63 16.63

Table 3

Time-Kill efficiency as a function of short-chain soaps between C10 and C14.

Reference sample Description Log ₁₀ reduction against E.coli ATCC 10536 at 20 second contact time Comparative Example C Soap bar enriched with Na caprylate 0.1±0.0 Example 6 Soap bar enriched with Na caprate >3.3 Comparative Example D Soap bar enriched with Na laurate 0.4 ± 0.2 Comparative Example E Soap bar enriched with Na myristate 0.0±0.0

As the data presented in Tables 2 and 3 show, among soap bars fortified with various short chain soaps, Na caprate soap alone has the best antimicrobial effectiveness in killing microorganisms over time. In other words, C ₁₀ soap is amazingly active when used in minimal quantities. It is the _C10 levels of 25.64 (where the ratio of specifically unsaturated _C18 to _C10 is 1.20) that causes death. _C8 , _C12 and _C14 provide much less activity.

Table 4

Soap bar compositions with increasing sodium caprate content

Comp. F Example 7 Example 8 Example 9 Sodium caprate 6.00 8.00 10.00 16.00 Sodium laurate 2.00 2.00 2.00 2.00 Sodium myristate 1.71 1.65 1.59 1.42 Sodium palmitate 23.71 22.91 22.11 19.70 Sodium stearate 26.48 25.58 24.69 22.00 Sodium oleate 0.31 0.30 0.29 0.26 Sodium linoleate 0.36 0.35 0.34 0.30 Sodium linolenate 0.04 0.04 0.04 0.03 Sodium ricinoleate 6.44 6.22 6.01 5.35 Glycerol 4.50 4.50 4.50 4.50 Trisodium citrate dihydrate 3.00 3.00 3.00 3.00 Talc 6.00 6.00 6.00 6.00 Sodium chloride 0.70 0.70 0.70 0.70 Na4Etidronate 0.04 0.04 0.04 0.04 Na4EDTA 0.17 0.17 0.17 0.17 Flavoring additive 1.185 1.185 1.185 1.185 CI 11980 0.06 0.06 0.06 0.06 CI 12490 0.06 0.06 0.06 0.06 Water 17.24 17.24 17.24 17.24

Table 5

Antimicrobial effectiveness depending on the sodium caprate content in the soap bar

Reference sample Description Time-kill efficiency
(Log ₁₀ reduction against E. coli ATCC 10536 at 30 second contact time) Comparative Example F Bar on the market (Lifebuoy bar data) 0.1±0.1 Example 7 Soap bar with 8% Na caprate 0.4 ± 0.1 Example 8 Soap bar with 10% Na caprate 1.2 ± 0.4 Example 9 Soap bar with 16% Na caprate >3.1

As the data presented in Tables 4 and 5 show, the antimicrobial effectiveness of killing microorganisms over time increases with increasing sodium caprate content in soap bar formulations. Examples show that _C10 levels as low as 8% work. The key is to keep oleate levels low relative to _C10 .

Table 6

Microbial killing efficiency over time for model bars containing 15.2 wt% Na caprate with 0.4 wt% carbonate buffering agent, containing varying levels of Na oleate

Reference sample wt.% Na oleate in the model bar Mass ratio of Na oleate to Na caprate Log ₁₀ reduction against E.coli ATCC 10536 at 30 second contact time Example 10 0.0 ---- 3.7 Example 11 6.1 0.40 2.2 Comparative Example G 25.0 1.64 0.28

Table 6 shows compositions containing 15.2% and various amounts of oleate. When unsaturated C ₁₈ (eg oleate) is absent (unhindered C ₁₀ activity), Example 10 shows good antimicrobial activity (log ₁₀ reduction of 3.7). The activity is still good in the presence of 6.1% oleate, provided that the ratio of C ₁₀ to oleate is low (Example 11). If the ratio is too high (comparative example G), the effect is very weak.

Table 7

Compositions of formulated bars with weight ratios of sodium oleate to sodium caprate ranging from 1 to 3.

Comparative Example H Comparative Example I Comparative Example J Sodium caprate 8.0 12.00 16.00 Sodium laurate 0.00 0.00 0.00 Sodium myristate 0.00 0.00 0.00 Sodium palmitate 35.22 35.22 35.22 Sodium stearate 2.76 2.76 2.76 Sodium oleate 24.29 24.29 24.29 Sodium linoleate 5.79 5.79 5.79 Sodium linolenate 0.00 0.00 0.00 Sodium ricinoleate 0.00 0.00 0.00 Glycerol 4.00 4.00 4.00 Trisodium citrate dihydrate 2.00 2.00 2.00 Talc 6.00 6.00 6.00 Sodium chloride 0.70 0.70 0.70 Na4Etidronate 0.04 0.04 0.04 Na4EDTA 0.17 0.17 0.17 Flavoring additive 1.185 1.185 1.185 CI 11980 0.06 0.06 0.06 CI 12490 0.06 0.06 0.06 Water 17.31 17.31 17.31

Table 8

Composition of Comparative Example 10/Ingredients Mass% Ratio of C10 soap: oleate soap 0.76 Sodium caprate 8.5 Sodium laurate 8.5 Sodium ricinoleate 6,528 Sodium Palmitate/Stearate (55:45) 45.68 Glycerol 4 Talc 6 Tetrasodium EDTA 0.04 Tetrasodium etidronate 0.166 Sodium chloride 0.7 Sodium citrate dihydrate 2 CI 12490 0.055 CI 11680 0.06 Flavoring additive 1.185 Water up to 100 Log Kill 30 sec 2.2

Data shows that the composition exhibits 2.2 log kill in 30 seconds at a sodium caprate level of approximately 8%. The ratio of oleate to caprate is 0.76. This composition is beyond the scope of the invention.

Table 9

Composition of Comparative Example 11/Ingredients Mass% Capric acid soap (C10 acid) 7.00 Lauric acid soap 7.50 Potassium hydroxide 0.00 Butylated hydroxytoluene 0.01 Glycerol 20.00 Sodium citrate dihydrate 6.00 Potassium chloride 1.50 Stearic acid (acid C16:C18, 55:45) 9.9 Sodium ricinolate 1.85 Sodium hydroxide 10.35 Etidronic acid 0.20 EDTA tetrasodium salt 0.10 Sorbitol 12.6 Sodium chloride 0.70 Isopropyl alcohol 2.50 Water Up to 100 Log Kill (30 seconds) 3.5 Oleate soap: C10 soap 0.26

Data shows that the composition exhibits 3.5 log kill in 30 seconds at a sodium caprate level of approximately 7%. The ratio of oleate to caprate is 0.26.

Claims (10)

1. A soap bar composition containing: a) 25-85%, preferably 35-75% by weight of C ₈ -C ₂₄ fatty acid soap containing: (i) C ₁₀ soap in an amount of 8% or 15% or more, more preferably 16-32% by weight of the total bar composition; And (ii) unsaturated C ₁₈ soap, wherein the weight ratio of said unsaturated C ₁₈ soap to C ₁₀ soap (caprate) is from 0.8 to 0.1, b) 1-45% organic and inorganic excipients by weight of the composition; And c) 5-30%, preferably 13-28% water by weight of the composition, where the excess of C ₁₀ soap relative to unsaturated C ₁₈ soap is at least 6%, and the unsaturated C ₁₈ fatty acid soap includes its hydroxy derivatives. 2. The composition according to claim 1, wherein the unsaturated C ₁₈ fatty acid soap is an unsaturated C ₁₈ fatty acid soap containing 1, 2 or 3 unsaturated groups or a mixture thereof. 3. Composition according to any one of paragraphs. 1 or 2, wherein said organic and inorganic excipients are selected from the group consisting of fillers, polyol, salts and mixtures thereof. 4. Use of the composition according to any of the preceding claims to impart antibacterial properties to a bar of soap. 5. Use according to claim 4, which provides a log10 reduction of E. coli ATCE 10536 at a hand contact time of 30 seconds of 1.2 or more.