CA1062580A - Light-duty liquid detergent compositions having enhanced skin mildness properties - Google Patents

Abstract

LIGHT-DUTY LIQUID DETERGENT
COMPOSITIONS HAVING ENHANCED
SKIN MILDNESS PROPERTIES

Vincent P. Heuring ABSTRACT OF THE DISCLOSURE
Liquid detergent compositions are disclosed having excellent sudsing and mildness characteristics and consisting essentially of:
1) from 10% to 35% by weight of an alkyl ether sulfate containing 10 to 15 carbon atoms in the alkyl group and an average degree of ethoxy-lation of from 3.5 to 6.5, the alkyl ether prior to sulfation and neutralization having been sub-jected to stripping to remove substantially all unethoxylated and the majority of the mono- and diethoxylated material;
2) from 1% to 5% by weight of a primary alkyl sulfate of 10 to 16 carbon atoms;
3) from about 0.25% to 3% by weight of a water-soluble alkali earth metal salt, preferably magnesium; and 4) the balance water.
Preferred compositions also include alkyl glyceryl ether sulfonate and trialkyl amine oxide surfactants, together with a solubilizing agent. The compositions display desirable sudsing properties and are outstandingly mild to the skin.

Description

BACKGROUND OF T~E INVENTION
This in~ention relates to liquid deterge-.t compositi.ons.
More particularly, it rel~tes to liquid detergent compositions comprising a mi~ture of surface-acti.ve comprun~s h-vin~ e~:ceptional sudsin~ and r~lildr.ess characteristics.

, -` ~062580 The quantity and persistence of suds are very important in light-duty liquid detergent compositions intended for dishwashing and the like. Frequently, the detergent capacity of a washing solution is gauged by the user by the amount of suds present and the persistence of suds for a reasonable period of time. Since the washing of dishes frequently constitutes exposure of the hands to a detergent solution, a suitable detergent composition must additionally be characterized by mildness to the skin. The attainment of the combined properties of desirable sudsing and mildness levels in li;quid detergent compositions is a matter of - difficult formulation. Liquid compositions having high sudsing qualities are often harsh on the skin. Conversely, liquid compositions characterized by desirable mildness to the hands of the user are frequently deficient in their sudsing and/or detergent qualities.
The employment of sulfated and neutralized ethoxylates has become widespread in part because of their desirable cleaning effects, excellent foam stability, and low cost. These detergents correspond to the formula R-(OC2H4~r-OSO3-M
where R is alkyl derived from a high molecular weight alcohol, M is a salt-forming cation, and r represents an average number of ethylene oxide groups. The products are derived by sulfation and neutralization of an ethoxylate derived by condensation of r moles of ethylene oxide per mole of a high molecular weight alcohol. Variations in the nature of the ethoxylate employed are known to cause changes in its sudsing and mildness properties, and improvements in one of these qualities have generally been obtained at the expense of the other. The product having an average ethylene oxide value of three (r) has been described in British Patent No. 791,704, March 12, 1958, as representing an optimum taking both mildness and detergency into account, and a formulation utilizing this alkyl triethoxy ether sulfate in combination with other surfactants to provide a product displaying desirable mildness and cleaning characteristics is disclosed in Eaton et al., U.S. Patent No. 3,179,599, issued April 20, 1965.
Another approach to this problem is represented by the compositions disclosed and claimed in U.S. Patent No. 3,793,233 to Rose and Thiele issued on February 19, 1974.
This patent discloses liquid detergent compositions containing a mixture of an alkyl sulfate and an alkyl ether sulfate in which 5 to 12 moles of ethylene oxide are condensed with one mole of a high molecular weight alcohol having 10 to 16 carbon atoms in the alkyl group.
However, both of these formulations are restricted in their ability to optimize sudsing and mildness characteristics by virtue of the broad distribution of ethoxylate species that results from the base catalyzed alcohol ethoxylation that is practiced commercially.
Accordingly, it is an object of the present invention to provide a light duty liquid detergent composition that displays outstanding mildness properties towards the skin.
It is another object of this invention to provide a light duty liquid detergent composition having outstanding mildness properties together with high sudsing characteristics.
SUMMARY OF THE INVENTION

_ The present invention is based in part upon the discovery that themildness properties of a liquid detergent composition can be enhanced by the use of an alkyl ether sulfate derived from an ethoxylated alcohol which has been subjected to stripping to remove unethoxylated and mono-ethoxylated material. Ethoxylation to a relatively low level (viz 3 to 4 moles of ethylene oxide per mole of alcohol) followed by stripping to remove unethoxylated and most of the mono- and diethoxylated alcohol, results in a material which, when sulfated and neutralized, provides enhanced mildness whilst not compromising sudsing to anything like the extent found hitherto. A combination with a low level of alkyl sulfate and water-soluble alkali earth metal ions provides compositions of very satisfactory mildness and sudsing characteristics.
- Thus the present invention provides a light-duty detergent composition consisting essentially of:
(a) from about 10% to about 35% by weight of the composition of a sulfated and neutralized alkyl ether of the formula Rl ~ (C2H4)n OSO3 wherein Rl is an al~yl residue which is linear or which contains 25% maximum of Cl-C3 branching in the 2-position, the alkyl residue having a mean chain length in the range of 10-15 carbon atoms, at least 65% by weight of said residue having a chain length within + 1 carbon atoms of the mean, wherein naV has a value within the range 3.5-6.5, provided (1) that the total weight of components in the alkyl ether in which n = 3 to 7 inclusive, shall be not less than 60% of the total weight of ethoxylated material, and (2) that the total weight of components in the alkyl ether in which n is 1 or 2 shall be not greater than 16% of the total weight of ethoxylated material, and wherein M is a monovalent cation selected from alkali metal, ammonium, alkyl- or alkanol-ammonium radicals;
(b) from about 1~ to about 5~ by weight of the composition of a water-soluble primary alkyl sulfate having 10 to 16 carbon atoms in the alkyl chain;
(c) from about 0.05~ to 1.0~ by weight of the composition of alkali earth metal ions present as a water-soluble salt; and (d) the balance water.
DETAILED DESCRIPTION OF THE INVENTION
Ethoxylated Alkyl Sulfate Component As previously indicated, sulfated and neutralized ethoxylate detergents are well known as a class of surfactants whose preparation and properties are described in The Journal of the American Oil Chemists Society, Vol. 36, pages 241-244 (June, 1959), Ibid, Vol. 37, pages 427-430 (September, 1960), Ibid, Vol. 45, pages 733-741 (November, 1968), in addition to the patents listed above.
The primary alcohol precursors of these materials are derived from natural and synthetic sources. Examples of suitable primary aliphatic alcohols are the linear primary alcohols obtained from the hydrogenation of vegetable or animal oil fatty acids such as coconut, palm kernel, and tallow fatty acids, or by ethylene build-up reactions and subsequent hydrolysis of the terminal double bond using Ziegler-type processes. Preferred alcohols are n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl, n-myristyl, and n-capryl alcohols.
Suitable alcohol precursors also include primary alcohols having a proportion of branching on the ~ or 2-carbon atom, i.e., of the formula:

CN3(CH2)n CN CN2N

(¦N2) m wherein m+n is in the range 6-13 and wherein m is 0-4.
In such alcohols at least 60% and preferably 75% by weigh~ of the alcohol of each specific chain length should be linear (i.e. m = 0) and the branching preferably comprises about 50% of methyl groups with smaller amounts of ethyl propyl and butyl groups. These alcohols, or the aldehydes corres-ponding thereto, are conveniently produced by reaction of linear olefins having from 7-14 carbon atoms with carbon mon-oxide and hydrogen. The reaction can either be controlled to produce aldehydes (as in the well known Oxo process), which aldehydes are then hydrogenated to give alcohols, or can be carried out as a hydroformylation reaction in which the alde-hydes are hydrogenated in situ to convert them to saturated C8 15 primary alcohols. sOth linear and branched chain alcohols are formed from these processes and the mixtures can either be used as such or can be separated into individual components and then recombined to give the desired blend.
Typical processes for producing "Oxo" aldehydes which are then hydrogenated to alcohols are disclosed in U.S.
20 Patents 2,564,456 and 2,587,858 and the direct hydroformylation of olefins to give alcohols is disclosed in U.S. Patents

2,504,682 and 2,581,988.
It will be apparent that by using a single chain length olefin as starting material, a corresponding single chain length alcohol will result, but it is generally more economic to utilize mixtures of olefins B

having a spread of carbon chain length around the desired mean. This will of course provide a mixture of alcohols having the same distribution of chain lengths around the mean.
Primary aliphatic alcohols derived from vegetable oils and fats and from other petroleum feedstocks having alkyl or alkylene groups as part of their structure will also contain a range of chain lengths. This range may extend over a range of C8 -C20 and beyond and it is therefore normal practice to separate the products from such feedstocks into different chain length ranges which are chosen with reference ~ to their ultimate use.
In such mixtures it is desirable for the purposes of the present invention that this distribution be as narrow as possible and therefore at least 65% and desirably 80% by weight of the alcohol mixture should be within + 1 carbon atoms of the mean chain length. Preferably at least 90~ and most preferably 95% should fall within ~ 1 carbon atoms of the mean chain length.
As mentioned previously, commercially available alcohol precursors normally comprise mixtures of alcohols, while materials suitable for the purposes of the present invention must have a narrow distribution of chain lengths around the given mean in order to minimize the range of condensates produced upon ethoxylation.
Commercially available primary alcohol blends satisfying this requirement include the alcohols mar-keted by Shell International Chemicals Ltd. under the trade mark Dobanol and similar materials marketed under the trade mark Neodols by Shell Chemical Co., these alcohol blends having at least 95% by weight of the blend within the stated carbon chain length range. Suitable alcohol blends derived from natural fats include the so-called "middle cut"
fraction of coconut fatty alcohol composed of approximately 70% C12, 20~ C14 and 10% C16 alcohol by weight.
It will be appreciated that alkyl ether sulfates derived from commercially available alcohol comprise a mixture of water-soluble salts. This mixture comprises a distribution of alkyl ether sulfate detergent molecules of varying ethylene oxide content. When a given number, for example, 6 moles of ethylene oxide are reacted with 1 mole of a high molecular weight alcohol, the resulting ethoxylated alcohol reaction product is comprised of a mixture of ether molecules having varying numbers of ethylene oxide groups. Generally, the mixture will contain a mixture of ether compounds wherein the mono-(ethylene glycol) ether derivative is present admixed with alkyl ether compounds containing a variable number of ethylene oxide groups extending from alkyl di-(ethylene glycol) ether to an alkyl poly-(ethylene glycol) ether wherein the number of ethylene oxide groups is equal to or greater than about twice the number of moles of ethylene oxide reacted with the high molecular alcohol.
The species having a number of ethylene oxide groups equal to the number of moles of ethylene oxide reacted with each mole of high molecular weight alcohol tends to predominate.
However, the higher the level of ethoxylation, i.e., the greater the average number of moles of ethylene oxide condensed with the alcohol, the broader the spread of ethoxylate species in the _ g 106Z5~0 product. Table 1, lines 1 and 2, shows the differing ethoxylate distributions of alkyl ether condensates obtained by ethoxylating one mole of C12 primary alcohol with an average of 3 and 11 moles respectively of ethylene oxide, the distribution being expressed as a percentage of the total weight of the condensate including the unethoxylated portion.

~ I a~ oo ~
~1 o ~
~1 u~ ~ , ....

o I u~

~ ~ o W I~D ~ , CO ~ Cl~
H ~D
C3 ~ N

W ¦ O N 11'7 N ' N ~D

. _ .
I~ ,~ ~ .

o ~1 1~ 0 ) ~~ ~ O

~06Z5~0 It can be seen that ethoxylation to an average value of three moles ethylene oxide per mole of alcohol provides a relatively high fraction of material having a level of ethoxylation in the range of 3 to 7 moles and also leaves significant quantities of unethoxylated (Eo)~ monoethoxylated (El), and diethoxylated (E2) material. These Eol El and E2 fractions in the triethoxylated material, while providing a useful sudsing component, are known to be disadvantageous to skin mildness. On the other hand, ethoxylation to a higher level, (line 2), while virtually eliminating the unethoxylated and monoethoxylated species, provides a much lower fraction - of ethoxylate in the target "mean" range and results in a very broad spread of ethoxylate levels. Furthermore, some loss in sudsing performance results as the higher ethoxylates (E6 and above) provide very little sudsing performance and, consequently, lower the overall performance of a given weight of material by a dilution effect.
The relative skin mildness of various ethoxylated alkyl sulfates is shown in Table II. This sets out skin irritancy values, assessed by a single application patch test technique for a series of ammonium linear alkyl ether sulfates in which the level of ethoxylation was varied from zero to four, using a synthesis technique which provided a single ethoxylate species.
In the single application patch test, a 1/2" square piece of cotton muslin is soaked with the test solution and applied to the back of the subject for a period of 24 hours.
It is then removed and the skin allowed to recover for a further 24 hour period, after which time the skin is graded according to the following scale.

Grading Scale for Patch Testing Grade 0 No apparent cutaneous involvement.
1/2 Faint, indistinct erythema, but something there, or no erythema, but slight dryness.
1 Faint but definite erythema, no eruptions or broken skin, or no erythema but definite dryness; may be epidermal fissuring.
2 Moderate erythema, may be a very few papu-lar eruptions, or isolated reaction like that of a grade 3 but not involving a significant portion of the patch area (e.g., around patch edges but not in the center). Dryness and epidermal fissuring are not major determining factors. No edema.

3 Se~ere erythema and generalized eruptions (papules, vesicles and/or crusts); entire patch site affected; reaction confined to actual patch site. Slight edema may be present.

4 Prominent edema and/or reaction extendingbeyond the patch area. Characteristics of grade 3 may be present.

Table II

C10 2.1 1.7 1.4 C12 2.5 1.6 1.4 1.1 0.9 C14 1.4 1.1 ~

It can be seen from Table II above that minimizing the unethoxylated mono- and diethoxylate species in a neutralized alkyl ether sulfate will significantly reduce the skin irri-tancy of the surfactant.
It has now been found that if the starting alcohol is ethoxylated to a lower than desired "average" level and the ethoxylate then subjected to "stripping", e.g., by vacuum distillation, to remove the Eo, most of the El, and a portion of the E2 components, a material can be obtained which has a higher average ethoxylate content, but has a lower level of the less useful higher ethoxylates. Line 3 of Table I illustrates a typical ethoxylate distribution of such a material.
As previously indicated, commercially available mat-erials useful in the present invention typically utilize the '-Neodol" and "Dobanol" alcohol blends, sold respective-ly by the Shell Chemical Co. and Shell International Chemicals Ltd., as alcohol precursors. These alcohol blends are condensed with 2.0 - 4 moles of ethy~ene oxide in the presence of a minor proportion of a strong base such as sodium hydroxide or potassium hydroxide using a process such as that disclosed in U.S. Patent 3,682,849.
Alcohol blends having a mean chain length of 12 carbon atoms or less such as Dobanol 91, Neodol 01, Neodol 12 are ethoxylated to give an uptake of about 2.0 to about 3.5 moles, preferably 2.5 to 3.0 moles of ethylene oxide per mole of alcohol. Neodol 23 typically requires 2.0 - 4.0 moles, pre-ferably 3.0 to 3.5 moles of ethylene oxide per mole of alcohol while Neodol 45 is conveniently ethoxylated to give an uptake of about 2,0 to about 4,0 moles, preferably 3.5-4.0 moles of ethylene oxide per mole of alcohol. The condensation products at this stage have a broad distribution of ethoxylates and a high level of free alcohol typical of base-catalyzed ethoxylation reactions and are quite unsuitable for the purposes of the present invention. Accordingly distillation or evaporation under sub-atmospheric pressure of the product to strip the unreacted alcohol and desirably also a major portion of the lower ethoxylates is carried out in the manner disclosed in U.S. Patent 3,682,849 in order to maximize the proportion of ethoxylates lying within the range 3-7 ethylene oxide groups per molecule of alcohol.
The narrower the distribution of carbon atoms around the mean alcohol chain length, the simpler will be the stripping process. Ideally the alcohol blends will be co~posed entirely of material falling in the stated chain length range so that there will be no overlap in boiling point between e.g.
unethoxylated alcohol of the highest chain length in the blend (which is undesirable) and di- or tri-ethoxylated alcohol of the lowest chain length in the blend (which is useful).
The amount of material to be removed normally lies in the range of 15-40% by weight of the ethoxylated alcohol and desirably in the range of 20-30% by weight in order to provide a narrow distribution of ethoxylates, whilst maintaining an economic process. This leaves an ethoxylate containing at least 60% and preferably at least 65% by weight of components in the E3-E7 range and also containing less than 16~ by weight, preferably less than 12% and most preferably less than 10% of El and E2 components, the above percentages being based on the total weight of ethoxylated species, i.e. excluding the unethoxylated alcohol.

10625~0 Sulfation of the condensate of fatty alcohol and ethylene oxide can be carried out batchwise or continuously employing chlorosulfonic acid or sulfur trioxide. Sulfur trioxide is normally used either as a liquid complexed with, e.g. Dioxan, or as a gas where it is diluted with an inert gas such as air or nitrogen. A temperature of from about 750E
to 1350E is suitable for the sulfation reaction. The sulfated product is neutralized by reaction with an alkali metal base, e.g., sodium hydroxide, potassium hydroxide, ammonium hydroxide, or alkylol-substituted ammonias. Preferred alkylol-substituted ammonias are mono-, di-, and triethanol amines;
~ mono-, di-, and triisopropanol amines; and mono-, di-, and triglycerol amines, i.e., those in which the alkylol group has from 2 to 3 carbon atoms. Depending upon the neutralizing agent employed in carrying out neutralization of the sulfated alcohol ethoxylate, M in the hereinbefore described formula will be a monovalent water-solubilizing cation such as sodium, potassium, ammonium, triethanolamine, or the like.
The advantages of using a "stripped" alkyl ~ther sulfate derived from a stripped alcohol ethoxylate are that it is possible to minimize the level of components known to be detrimental to skin mildness, namely, the Eo~ El, and E2 materials, while not ethoxylating to an extent that introduces appreciable quantities of non-useful material, i.e., the higher ethoxylates. This results in a more economical use of the feedstock, as less needs to be employed to obtain a given level of performance.
The level of the "stripped" alkyl ether sulfate in compositions of the present invention is from about 8%
to about 35% by weight of the composition, preferably from 10% to 30%, and most preferably from 18% to 24% by weight.

106ZS8C~

~lkyl Sulfate Component Notwithstanding the better sudsing that is obtainable with stripped alkyl ether sulfates of a given level of mildness compared to unstripped alkyl ether sulfates of the same level of mildness, it has been found that a low level of water-soluble primary alkyl sulfate is necessary to obtain satisfactory sudsing properties. ~owever, this level is very much lower than that previously employed, being in the range of 1~ to 5~ by weight, preferably 2% to 4% by weight of the composition.
The water-soluble alkyl sulfate component of the present invention conforms to the general formula wherein R is as defined hereinbefore, and M may be a monovalent cation as hereinbefore defined or may be a divalent cation provided by the third essential component of the invention.
Preferred materials are the alkyl sulfates in which the alkyl group is derived from coconut oil and the synthetic primary alcohols available under the trade name "Neodol" or "Dobanol", particularly those having 12 to 13 carbon atoms in the alkyl chain.
Water-Soluble Alkali Earth Metal Salt Component Alkali earth metal ions such as magnesium, calcium, and barium ions form a third essential component of the present invention. These ions, in combination with the alkyl sulfates and alkyl ether sulfates, provide compositions having the desired sudsing performance, particularly in water having low levels of mineral hardness. One method of introducing the ions is via direct neutralization of the primary alkyl sulfuric acids. Alternatively, the ions may be added in the form of water-soluble salts as solids or more preferably as aqueous solutions during the making process. Typical but non-limiting examples of water-soluble salts useful in the present invention are magnesium sulfate, magnesium chloride, calcium chloride, and barium chloride.
The alkali earth metal ions are utilized at a level of from about 0.05~ to about 1% by weight, preferably 0.1%
to 0.5~ by weight of the composition. If the alkali metal ions are added as water-soluble salts, they are conveniently used at a level of from 0.25% to 3%, preferably 0.5% to 2.0%
by weight of the composition.
Optional Components The compositions of the invention, in addition to the presence of the alkyl ether sulfate and alkyl sulfate components described hereinbefore, can contain water-soluble detergent compounds. Suitable detergents are those which do not interfere with the desirable detergent, sudsing and mildness properties of the compositions of the invention. Such materials should be employed in non-interfering amounts so as to avoid the minimization or masking of the advantageous properties of the combined alkyl ether sulfate and alkyl sulfate components of the invention. Suitable water-soluble detergents include anionic (e.g., alkali metal salts of alkyl benzene sul-fonates, alkyl glyceryl ether sulfonates, olefin sulfonates), non-ionic (e.g., alkylene oxide condensates of aliphatic and alkyl _ G 106Z580 aromatic compounds), ampholytic (e.g., sodium 3-dodecylamino-propionate), and zwitterionic (e.g., 3-(N,N-dimethyl-N-hexa-decylammonio)propane-l-sulfonate and 3-(N,N-dimethyl-N-hexa-decylammonio)-2-hydroxypropane-1-sulfonate) detergents. Suit-able examples of water-soluble detergents are described in U.S. Patent 3,351,558 (November 7, 1967) at column 6, line 57, to column 9, line 74. Preferred olefin sulfonates are the olefin sulfonates having from about 10 to about 24 carbon atoms and obtained by sulfonation of -olefins with gaseous sulfur trioxide. These include the alkali metal and am-monium tetradecene and hexadecene sulfonates. Other examples are described in U.S. Patent 3,332,880 (July 25, 1967).
Preferred detergents herein include the alkyl glyceryl ether sulfonates such as those described in David D. Whyte et al, U.S. Patent 3,024,273 issued March 6, 1962 and tri-alkyl amine oxides such as those disclosed in Drew et al, U.S. Patent 3,223,647, issued December 14, 1964. Amine oxides are preferably employed at levels ranging from 1% to 10~, preferably 2~ to 6~ by weight of the compositions while the alkyl glyceryl ether sulfonates are utilized in amounts of from 1~ to 8%, preferably 2% to 6% by weight. Mixtures of these detergents can be employed.
The detergent compositions of the invention can con-tain any of the usual detergent adjuvants. For example, solubilizing agents, viscosity control agents such as toluene sulfonates and xylene sulfonates, perfumes , anti-tarnishing agents, opacifiers such as ethylene glycol di-stearate or polystyrene, inert salts such as sodium sulfate, antiredeposition agents, bacteriostatic agents, dyes, fluorescers, suds builders, and the like, can be utilized herein without detracting from the advantageous properties of these compositions. Suitable solubilizing agents ~`~ 106Z580 include methyl, ethyl, n-propyl, and isopropyl alcohols and are employed in an amount of from about 5% to 12% of the composition of the invention.
An additional component that can advantageously be included is a modified protein for further enhancing the mildness properties of the detergent composition. Materials of this type constitute proteins of molecular weight exceed-ing 5000, preferably in the range of 20,000 to 200,000, which have been modified by reaction of the free carboxylic acid or amino groups with one or more of a variety of functional groups such as oxyalkylene, acyl, alkyl, aryl, nitro, mercapto, amido, and the like. A particularly preferred modification is one in which base-hydrolyzed gelatin of molecular weight 50,000 to lO0,000 is oxybutylated.
Liquid detergent compositions incorporating such modified proteins form the subject of Marsh et al, U.S.
Patent 4,115,548, issued September l9, 1978.
The detergent compositions of the invention can be formulated by conventional methods. For example, the alkyl ether sulfate, alkyl sulfate, and optional components can be incorporated into aqueous solution individually or in combination. The alkyl sulfate and alkyl ether sulfate components are preferably added in admixture. A preferred means of effecting simultaneous addition involves preparation _ situ of alkyl sulfate during the preparation of the alkyl ether sulfate component.

A

10625~0 The desirable sudsing and mildness characteristics of the liquid detergent compositions of the invention are apparent from the following Examples which serve to illustrate the invention. All parts set forth herein are by weight unless otherwise indicated.
EXAMPLE I
Three compositions were prepared whose formulations were as follows:
(1) (2) (3) NH4AE3S( ) 25.0 4 12 18.75 4 4.75 21.0 NH4AS 6.25 3.1 MgC12 1.1 Lauryl Dimethyl 5.0 5.0 5.0 Amine Oxide NH4 Coconut Alkyl 4 0 4 0 4 0 Glyceryl Ether Sulfonate Ethanol 8.75 8.75 8.75 Minors 5.0 5.0 5.0 Perfumes, Viscosity, Modifiers, Opacifiers, Color, pH Buffers, Etc.
Water -------- to 100% -----(a) = Alcohol ethoxylate precursor comprises middle cut coconut alcohol condensed with an average of three ethylene oxide groups. (Ethoxylate distribution as in line 1 of Table 1.) (b) = Alcohol ethoxylate precursor comprises middle cut coconut alcohol condensed with an average of twelve ethylene oxide groups. (Ethoxylate distribution as in line 2 of Table 1.) (c) = Alcohol ethoxylate precursor comprises Meodol 23, linear oxo alcohol containing approximately 10% 2-methyl branched of which approximately 30 ~ 95% of the alkyl chains are C12 or C13 groups, condensed with an average of approximately three moles of ethylene oxide and then stripped to remove 30~ of the ethoxylate to leave a material having an average degree of ethoxylation of 4.75 with approximately 69% of the ethoxylate in the E3-E7 range and less than 10% of El and E2 components. ~Ethoxylate distribution as in line 3 of Table l.) In order to evaluate the sudsing ability of these compositions, 7 cc. of each of the compositions was added to a dishpan containing one gallon of water of a selected hardness (2, 7 and 14 grains) at a temperature of 115F, and a pH of 8.
Suds were generated by mechanical agitation (small propeller) and the suds level measured. A fixed quantity (about 5 grams) of standardized fatty soil (a triglyceride shortening) was placed on a dinner plate which was then wa~hed in the test solution. The plate was re-soiled and washed, repeating this procedure a total of five times. Five additional sets of five soiled plates were washed in the solution in like manner, measuring the foam height after each set. The foam height after washing each set was expressed in terms of precent of original suds height and an average of the five percentage values was computed and is reported below. A difference of about 5% in foam height is considered significant and noticeable by the housewife. Results are recorded in the table below for each water hardness. The rate of suds generation was also recorded for the solutions with no soil present. In order to measure this property, a device is used comprising a recirculating system in which a solution of the composition (7 cc. in one U.S. gallon) is withdrawn from the bottom of a graduated cylindrical vessel and pumped back to a downward-facing orifice located in the vessel above the solution surface. The solution issues vertically downwardly in a jet which impinges on the solution surface and generates suds. The volume of ~uds (in ml.) generated after two minutes is measured.

106Z5~30 Composition ~ Origina] Suds Suds Volume eight After 2 Mins.

Grains Grains 2 48 47 45.5 585 565 3 49.5 52 46 610 605 As can be seen from the data in the preceding table, the composition of the invention (Composition 3) is characterized by sudsing properties (speed and stability) which are superior to comparable compositions containing an ammonium salt of a sulfated condensate of one mole middle cut coconut alcohol and 3 moles ethylene oxide (Composition 1) or an ammonium salt of a sulfated condensate of one mole middle cut coconut alcohol and 11 moles ethylene oxide (Composition 2).
Stratum Corneum Test Solutions of products 1, 2, and 3 (0.2% by weight) were made up in water of 7 grains mineral hardness (Ca:Mg = 3:1) per U.S. gallon. A small piece of isolated stratum corneum 10 microns thick and 1/2 cm2 in area was soaked in each product solution which was maintained at a temperature of 100F. Each piece was periodically removed from its solution, carefully dried with blotting paper to remove supernatant moisture and then weighed on a Cahn Electrobalance, before being immediately returned to the solution.
The water uptake was measured over a period of approximately 1-1/2 hours and the results are indicated below expressed as a percentage increase in the original weight in each case ~ 1062580 Product --Time Minutes----~

The percentage weight gain is a function of the extent to which the stratum corneum piece is degraded and hence penetrated by the solution in which itis immersed. It can therefore be seen from the above table that the composition in accordance with the present invention gives rise to a significantly lower level of degradation than formulae previously considered to be mild.
Equivalent results to the above are obtained if the C12-C13 stripped alkyl ether sulfate is replaced by either of the following: (1) an alkyl ether sulfate derived from an alcohol ethoxylate precursor comprising a C14-C15 linear primary alcohol condensed with an average of approximately 4 moles of ethylene oxide and then stripped to remove 27.0%
by weight of the ethoxylate constituted by the lower boiling fractions (Eo~ El, and E2), to leave a material having an average degree of ethoxylation of 5.9, having 60% by weight of E3-E7 components and <6% of El and E2 components; and (2) an alkyl ether sulfate derived from an alcohol ethoxylate precursor comprising Dobanol 91 (a linear Cg-Cll primary alcohol blend) condensed with approximately 2.5 moles of ethylene oxide and then stripped to remove 34% by weight of the ethoxylate to leave a material having an average degree of ethoxylation of 4.1, having 69.7% by weight of E3-E7 components and 15.5% of El and E2 components.

Claims (16)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A light-duty detergent composition consisting essentially of:
(a) from about 10% to about 35% by weight of the composition of a sulfated and neutralized alkyl ether of the formula R1 - (C2H4O)nav OSO3M

wherein R1 is an alkyl residue which is linear or which contains 25% maximum of C1-C3 branching in the 2-position, the alkyl residue having a mean chain length in the range of 10-15 carbon atoms, at least 65% by weight of said residue having a chain length within ?1 carbon atoms of the mean, wherein naV has a value within the range 3.5-6.5, provided (1) that the total weight of components in the alkyl ether in which n = 3 to 7 inclusive, shall be not less than 60% of the total weight of ethoxylated material, and (2) that the total weight of components in the alkyl ether in which n is 1 or 2 shall be not greater than 16% of the total weight of ethoxylated material;
and wherein M is a monovalent cation selected from alkali metal, ammonium, alkyl- or alkanolammonium radicals;
(b) from about 1% to about 5% by weight of the composition of a water-soluble primary alkyl sulfate having 10 to 16 carbon atoms in the alkyl chain;
(c) from about 0.01% to 1.0% by weight of the composition of alkali earth metal ions present as a water-soluble salt; and (d) the balance water.

2. A light-duty detergent composition according to claim 1 wherein the alkyl ether sulfate is derived from an alkyl ether having an average of 12-13 carbon atoms in the alkyl residue, at least 90% by weight of the alkyl residue being composed of alkyl groups having no less than 11 and no more than 14 carbon atoms and wherein 4.2 <naV <5.5.

3. A light-duty detergent composition according to claim 2 wherein the total weight of components in the alkyl ether in which n is 1 or 2 is less than 12% of the total weight of ethoxylated material.

4. A light-duty detergent composition according to claim 2 wherein nav is about 4.75.

5. A light-duty detergent composition according to claim 1 wherein the alkyl ether is produced by base catalyzed ethoxylation of a primary alcohol followed by evaporative stripping of the ethoxylate to remove the unethoxylated and at least part of the mono- and diethoxylated alcohol.

6. A light-duty detergent composition according to claim 1 wherein the alkali earth metal is magnesium.

7. A light-duty detergent composition according to claim 1 further comprising from about 2% to about 8% of an alkyl glyceryl ether sulfonate having a linear alkyl group of 12-14 carbon atoms and wherein the cation of the sulfonate is alkali metal ammonium or alkanolammonium.

8. A light-duty detergent composition according to claim 7 further comprising from about 2% to about 10% of a trialkylamine oxide having one linear alkyl group of from about 12 to about 14 carbon atoms and two short chain alkyl groups of 1-2 carbon atoms.

9. A light-duty detergent composition according to claim 1, also comprising a solubilizing agent selected from the group consisting of methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, and mixtures thereof.

10. A light-duty detergent composition consisting essentially of:
(a) from about 18% to about 24% by weight of the composition of a sulfated and neutralized alkyl ether of the formula R1 - (C2H4O)nav OSO3M

wherein R1 is an alkyl residue having an average of 12-13 carbon atoms in the alkyl chain, at least 90% by weight of the alkyl residue being composed of alkyl groups having no less than 11 carbon atoms and no more than 14 carbon atoms and wherein 4.2 <nav <5-5, provided (1) that the total weight of components in the alkyl ether in which n = 3 to 7 inclusive is not less than 65% of the total weight of ethoxylated material, and (2) that the total weight of components in the alkyl ether in which n is 1 or 2 shall not be greater than 10% of the total weight of ethoxylated material;
and wherein M is a monovalent alkali metal, ammonium, alkyl- or alkanolammonium radical;
(b) from about 2% to about 4% by weight of the composition of a water-soluble primary alkyl sulfate having 10 to 16 carbon atoms in the alkyl chain;
(c) from about 0.1% to about 0.4% by weight of the composition of magnesium ions present as a water-soluble salt thereof;
(d) from about 2% to about 8% of an alkyl glyceryl ether sulfonate having a linear alkyl group of 12-14 carbon atoms and wherein the cation is a monovalent radical as defined above;

(e) from about 2% to about 10% of a trialkylamine oxide having one linear alkyl group of 12-14 carbon atoms and two short chain alkyl groups of 1-2 carbon atoms; and (f) the balance water.

11. A light-duty detergent composition according to claim 10 wherein the alkyl ether is produced by base catalyzed ethoxylation of a primary alcohol followed by evaporative stripping of the ethoxylate to remove the unethoxylated and at least part of the mono- and diethoxylated alcohol.

12. A light-duty detergent composition according to claim 10, also comprising a solubilizing agent selected from the group consisting of methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, and mixtures thereof.

13. A light-duty detergent composition according to claim 10 wherein the monovalent cation is ammonium.

14. A light-duty detergent composition according to claim 10 wherein the magnesium ions are incorporated into the composition as magnesium chloride.

15. A light-duty detergent composition according to claim 10 also incorporating a modified protein material as a skin emollient.

16. A light-duty detergent composition according to claim 15 wherein the modified protein is a butoxylated gelatin.