GB1585984A - Light duty non-irritating detergent compositions - Google Patents

Description

(54) LIGHT DUTY NON-IRRITATING DETERGENT COMPOSITIONS (71) We, SHEREX CHEMICAL COMPANY INC., a Corporation organized and existing under the laws of the State of Ohio, United States of America, of 5200 Blazer Parkway, P.O. Box 646, Dublin, Ohio 43017, United States of America, do hereby declare the invention for which we pray that a Patent may be granted to us and the method by which it is to be performed to be particularly described in and by the following statement: This invention relates to detergent compositions and in particular to liquid, low irritation detergents, such as shampoos.

Most shampoos and light duty household detergent products are based on the combination of an anionic surfactant (e.g. sodium lauryl sulphate, sodium lauryl ether sulphate (SLES) and linear alkyl benzene sulphonate) and a surface active agent serving as a foam promoter and stabilizer (e.g. a tertiary amine oxide or an alkanolamide). All of these surface active agents and particularly the anionic surfactants are severe eye irritants and are capable of causing mild to moderate skin irritation to some persons. Lately, there has been a trend towards use of the anionic in combination with an amphoteric type surfactant and combining with these compounds an ethoxylate of a partial polyol ester of a higher fatty acid to reduce irritation.

Products of this type, such as the so-called 'baby shampoo' formulations, are 'mildly irritating' in accordance with the Draize eye irritation test. While it would be desirable to provide even blander systems in this respect than are now available an equally important objective is obtaining systems which allow control of viscosity characteristics of the final products. Most detergent compositions of the type herein concerned are marketed as water systems containing from about 10 to 30 percent active content. The standard method for increasing viscosity at the indicated range of solids content has been the addition of common salt, which increases eye irritation.

The invention has been made with the above points in mind.

According to the invention there is provided a detergent composition having an active content comprising: a) an alkylene oxide adduct of a partial glycerol ester of a fatty acid having 10 to 18 carbon atoms, the partial glycerol ester having a monoglyceride content of from 15 to 45% by weight with the balance essentially consisting of diglyceride, the adduct having been prepared by reacting the partial glycerol ester with ethylene oxide,' propylene oxide or a mixture thereof in which the molar ratio of ethylene oxide to propylene oxide is from 2:1 to 4.5:1, in a molar ratio of partial glycerol ester to alkylene oxide of from 1:15 to 1:100, and b) an anionic surface active agent which is a salt of a higher alkyl sulphate, a salt of a higher alkyl ether sulphate, a salt of a higher alkyl benzene sulphonate or any combination thereof, the weight ratio of component a) to component b) being from 1:1 to 4:1.

The detergents may optionally include a foam stabilizing amount of an alkanolamide or a tertiary amine oxide. Control of the viscosity of detergent systems whose concentrations generally vary between 15 to 65% solids is easily attained by varying the concentration of component a).

The invention will be described with reference to the accompanying drawings in which: Figure 1 illustrates the change in eye irritations as determined in accordance with the Draize eye irritaion test resulting from combining the anionic surfactant SLES with varying amounts of a representative nonionic surfactant.

Figure 2 illustrates the manner whereby the viscosity of a typical shampoo formulation at a conventional range of solids content can be varied by appropriately altering the hydrophobicity characteristics of the nonionic surfactant component. The lower the amount of alkylene oxide in the nonionics the lower the viscosity of the detergent system.

Figure 3 shows the same viscosity effect as that shown in Figure 2 with alkoxylates prepared from mixtures of propylene oxide and ethylene oxides.

The anionic surfactants useful in the practice of this invention are standard items of commerce and hence need not be further elaborated upon herein. The 'higher alkyl' groups in the anionic surfactants contain at least 8 carbon atoms.

Applicable salts thereof are those of an alkali metal hydroxide, preferably sodium hydroxide, ammonium hydroxide, a hydroxy alkyl amine, etc. The nonionic surfactants although available from commercial sources nevertheless warrant a brief description as to how they can be made. These nonionic surfactants are derived from partialy glycerol esters of a higher fatty acid. The applicable higher fatty acids are the saturated or unsaturated, preferably the saturated type, of the so-called detergent grade acids having a carbon atom content of from about 10 to 18. Such partial esters consist essentially of a mixture of monoglycerides and diglycerides, where the monoglyceride content is from about 15 to 45 wt. %, preferably from 25 to 35 wt. %. The balance of the partial ester product will be predominantly the corresponding diglyceride.

These mono- and diglyceride mixtures can be readily prepared by the glycerolysis of a triglyceride in the presence of a basic catalyst, preferably an alkali metal hydroxide.

Alternatively, they can be prepared by directly esterifying glycerin with the fatty acids. The molar ratio of trigylceride to glycerin can be adjusted in carrying out the preferred glycerolysis method to result in a reaction product having the desired monoglyceride content (normally equimolar).

The nonionic surfactants are the alkylene oxide adduct of the partial glycerol esters described above. They are structurally characterized as having a polyoxyalkylene chain of oxyethylene, oxypropylene, or randomly distributed oxyethylene and oxypropylene residues in the ratio of 2:1::4.5:1, respectively. The chain length of the polyoxyalkylene group is essentially governed by amount of the alkylene oxide employed in relation to the partial ester. On this basis, a range of from 15 to 100 moles of the alkylene oxide per mole of the partial ester is broadly applicable.

When mixtures of propylene oxide and ethylene oxide are used, the random nature of the polyoxyalkylene chain is an important factor in providing liquid products. This randomness is realized primarily by the manner in which the ethylene oxide and propylene oxide are reacted with the partial ester. The preferred mode consists of simultaneously adding both alkylene oxides in the selected ratio to the partial ester upon effecting the adduction reaction. Alternatively, the alkylene oxides can be added as a preformed mixture thereof.

The process conditions otherwise applicable conform to standard practices observed in carrying out this reaction. Such include use of a suitable catalyst; e.g.. an alkali metal hydroxide, and an operating temperature preferably in the order of about 1500 to 1800C.

The reaction is ordinarily conducted in a closed system at a pressure of from 2 to 10 atmospheres.

The nonionic surfactant is combined with that amount of the anionic surfactant which provides an overall composition denoted as "minimally irritating" to the eye in accordance with the Draize test. Maximum mean eye irritation scores of from 1 to about 18 are classified as conforming to this category of irritation. The general method for evaluating and scoring in accordance with this test is outlined in the J. Pharmacol. and Exp. Ther. 82, page 377 (1944) as well as in Section 191.12 of Federal Hazardous Substance Act. The ratio of nonionic to the anionic for achieving the indicated level of irritation is at least about one part by weight of the nonionic surfactant to one part of the anionic surfactant: inclusion of a foam stabilizer will normally require increased level of nonionic.

Figure 1 shows the eye irritation levels exhibited bv various combinations of a representative ethoxylated nonionic surfactant and SLES. Maximum mean eye irritation scores from 1 to about 18 are classified as being "minimally" irritating. Thus, it can be seen that where the nonionic and anionic surfactants are combined on about an equal weight basis. this low level of irritation is realized. As further shown in the graph, the effect of increasing the proportion of the nonionic surfactant to anionic surfactant is such that an irritation value substantially less than 10 is asymptotically reached at about a ratio of 2:1.

respectively. While only a minimal change in eye irrittion value occurs beyond this ratio there still may be a need or an advantage attendant to the use of higher ratios of the nonionic to anionic surfactant from the standpoint of viscosity control. all as will be subsequently explained.

The inclusion of a foam stabilizer has the effect of increasing the eye irritation characteristics of the system beyond that normally to be expected. However, this increase can be compensated for by moderately increasing the minimum ratio of nonionic to anionic surfactant. Generally, the amount of foam stabilizer is based upon the amount of the anionic surfactant component present in the system, and is from about 20 to 25% of the anionic surfactant component. Amounts of the foam stabilizer less than 20% results in less than optimum foam stabilization properties, while amounts in excess of 25% causes rinsing problems. Thus, when the foam stabilizers are included within the indicated range of two parts by weight to the nonionic to one part by weight of the anionic surfactant will provide an overall composition having a mean eye irritation score in the "minimally" category.

As mentioned above, an important feature of the present invention resides in the ability to regulate the viscosity of aqueous solutions of the contemplated detergent systems by appropriate selection of the nonionic surfactant component. This feature is illustrated in Figure 2, where viscosity is plotted against percent solids of a typical aqueous shampoo system. The active content of the system used for this illustration corresponds to formulation No. 8 of Example 1 (Table 1) and as such includes, on a solid weight basis, 23.9% of SLES, 71.4% of the ethoxylated nonionic surfactant and 4.6% of a commercial superamide. The preparation of the two ethoxylates shown in Figure 2 is described in the example.

As can be noted from Figure 2, the viscosity of the aqueous system is dependent upon the nature of the ethoxylated nonionic surfactant and also on the percent of total solids in the system. As shown, the greatest buildup of viscosity can be achieved by using a 40 mole adduct of a mixture of mono- and diglycerides derived from tallow; A 60 or 100 mole adduct would give even greater viscosity buildup. On the other hand, substituting a 30 mole adduct of a comparable partial ester mixture of coconut fatty acids therefor permits higher solids levels in obtaining the corresponding viscosity associated with the use of the tallowate adduct. Further, it can be seen that complete control of viscosity characteristics can be achieved within the normal range of solids concentration of the detergent system by judiciously blending these two representative partial glycerol adducts.

EXAMPLE 1 PEG 30 glycerol cocoate Into a suitable reaction vessel were charged 2335 parts (3.57 moles) refined coconut oil, 345 pars (3.75 moles) glycerin, and 5.4 parts of 50% aqueous KOH. With stirring, the reaction mixture was heated to llO"C. and held for one hour under 20 mm vacuum. The reaction mixture was then heated to 165"C. with a nitrogen spare and held for 3 hours.

To a pressure vessel was charged 254.5 parts (0.6 mole) of the above mono- and diglyceride mixture. The reactor was purged twice with nitrogen and heated to 1500C.

Ethylene oxide in the amount of 800 parts (18.2 moles) was added over an 8-hour period while maintaining the temperature at 150-160"C. Upon cooling the reaction mixture to about llO"C., 25sic aqueous sulfuric acid was added for neutraliztion (pH 8) and the reaction mixture then filtered.

PEG 40 glycerol tallouate In a manner described above one mole of tallow was reacted with 1.05 mole of glycerin in the presence of potassium hydroxide to provide a mixture of tallow mono- and diglycerides.

Following stripping to remove moisture, the partial ester mixture was then reacted with 40 moles of ethylene oxide as per the procedure outlined above whereupon the ethoxylated product was cooled, stripped and filtered.

In the following Table I. the irritation data given refer to that derived in accordance with the Draize test method. The foam stabilizer indicated is a coco diethanolamide (VARAMIDE MA1 - ASHLAND CHEMICAL CO.). The percentages of the active components are set forth with the balance being water.

TABLE I Shampoo formulations Wt. % of active components PEG 30 Coco Mean IRR Ratio No. SLES(2) Glyc.cocoate(l) Superamide IRR score class. (1)/(2) 1 4.8 22.0 1.2 10.0 Minimally 4.6/1 2 8.0 18.0 2.0 19.7 Mildly 2.3/1 3 6.4 20.0 1.6 6.4 Minimally 3.1/1 4 5.6 21.0 1.4 6.0 Minimally 3.8/1 5 7.2 19.0 1.8 9.3 Minimally 2.6/1 6 5.0 22.0 1.0 4.0 Minimally 4.4/1 7 8.3 18.0 1.7 5.3 Minimally 2.2/1 8 6.7 20.0 1.3 3.3 Minimally 3.0/1 9 5.8 21.0 1.2 5.0 Minimally 3.6/1 10 7.5 19.0 1.5 5.3 Minimally 2.5/1 EXAMPLE 2 35(3EOIPO) Glycerol cocoate Into a suitable reaction vessel were charged 2335 parts (3.57 moles) refined coconut oil, 345 parts (3.75 moles) glycerin, and 5.4 parts of 50% aqueous KOH. With stirring, the reaction mixture was heated to llO"C. and held for one hour under 20 mm vacuum. The reaction mixture was then heated to 165"C. with a nitrogen sparge and held for 3 hours.

To a pressure vessel was charged 140 parts (0.33 mole) of the above mono- and diglyceride mixture. The reactor was purged twice with nitrogen and heated to 1500C. A preformed mixture of alkylene oxides containing 385 parts (8.7 moles) of ethylene oxide and 169 parts (2.91 moles) of propylene oxide was added over an 8-hour period while maintaining the temperature of 150-160"C. Upon cooling the reaction mixture to about llO"C., 25% aqueous sulfuric acid was added for neutralization (pH 8) and the reaction mixture then filtered.

82 (3EOIPO) Glycerol tallowate In a manner described above one mole of tallow was reacted with 1.05 mole of glycerin in the presence of potassium hydroxide to provide a mixture of tallow mono- and diglycerides.

Following stripping to remove moisture, a mole aliquot of the partial ester mixture was then reacted with a preformed mixture of 61.5 moles of ethylene oxide and 20.5 moles of propylene oxide as per the procedure outlined above whereupon the alkoxylated product was cooled, stripped and filtered.

EXAMPLE 3 An 82(3EO/PO)glycerol cocoate (Nonionic A) and a 35 (2EO/PO) glycerol'tallowate (Nonionic B) were prepared following the general procedure outlined in Example 2.

Aqueous shampoo formulations were prepared using said adducts as the nonionic surfactant component thereof and tested for eye irritation properties in accordance with the Draize method. The indicated foam stabilizer in formulation No. 2 was a commercial coco superamide (VARAMIDE MA1 - ASHLAND CHEMICAL CO.). Further details relative to the make-up of these systems and the test results obtained are set forth in the following Table II.

TABLE II Aqueous shampoo formulations Wt. % of active components Coco Mean No. SLES Nonionic A Nonionic B Superamide IRR. score 1 9.1 18.2 - - 5.3 2 8.3 18.0 - 1.7 4.7 3 9.1 - 18.2 - 4.7 The alkoxylation can also be carried out using mixtures of ethylene oxide and propylene oxide. The viscosity-percent solids relationships with mixed propylene-ethylene alkoxylates are show in Figure III. The active content of the system used for Figure III corresponds to formulation No. 2 of Example 3 (Table II) and, as such, includes on a solid basis 39.6 wt. % SLES, 64.3% of the nonionic surfactant and 6.1% of a commercial diethanolamide. The preparation of the nonionic surfactants is given in Example 2.

As can be noted from the drawing, the viscosity of the aqueous system is primarily dependent upon the nature of the nonionic surfactant and the percent of total solids in the system. As shown, the greatest build-up of viscosity can be achieved by using the 82-mole polyoxyalkylene adduct of an equilibrated reaction mixture of mono- and diglycerides derived from tallow wherein the polyoxyalkylene chain is composed of randomly distributed oxyethylene and oxypropylene residues in the ratio of 3:1 respectively. On the other hand, substituting a similar 35-mole oxyalkylene adduct of a comparable partial ester mixture of coconut fatty acids therefore permits higher solids levels in obtaining the corresponding viscosity of the use of said tallowate adduct. Further, it can be seen that control of the viscosity characteristics ca be realized within the normal range of solids concentration of a detergent system by judiciously blending these two representative partial glycerol ester adducts.

Example 3 (Table II) illustrates the low degree of eye irritation associated with typical detergent shampoo systems based on mixed propylene/ethylene alkoxylates.

WHAT WE CLAIM IS: 1. A detergent composition having an active content comprising: a) an alkylene oxide adduct of a partial glycerol ester of a fatty acid having 10 to 18 carbon atoms, the partial glycerol ester having a monoglyceride content of from 15 to 45% by weight with the balance essentially consisting of digylceride, the adduct having been prepared by reacting the partial glycerol ester with ethylene oxide, propylene oxide or a mixture thereof in which the molar ratio of ethylene oxide to propylene oxide is from 2:1 to 4.5:1, in a molar ratio of partial glycerol ester to alkylene oxide of from 1:15 to 1:100, and b) an anionic surface active agent which is a salt of a higher alkyl sulphate, a salt of a higher alkyl ether sulphate, a salt or a higher alkyl benzene sulphonate or any combination thereof, the weight ratio of component a) to component b) being from 1:1 to 4:1.

2. A detergent composition as claimed in Claim 1 in which the ratio of component a) to component b) is from 2:1 to 5:1.

3. A detergent composition as claimed in Claim 1 or Claim 2 which additionally comprises: c) a foam stabilizing agent which is an alkanolamide, a tertiary amine oxide or a mixture thereof, the ratio of component b) to component c) being from 4:1 to 5:1.

4. A detergent composition as claimed in any preceding claim in which the anionic surface active agent is sodium lauryl sulphate, sodium lauryl ether sulphate or a sodium alkyl benzene sulphonate in which the alkyl group contains 12 to 18 carbon atoms.

5. A detergent composition as claimed in Claim 1 substantially as herein described with reference to any one of the Examples.

6. A detergent composition as claimed in Claim 1 substantially as herein described with reference to Figure 3 of the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (6)

**WARNING** start of CLMS field may overlap end of DESC **. oxide. The viscosity-percent solids relationships with mixed propylene-ethylene alkoxylates are show in Figure III. The active content of the system used for Figure III corresponds to formulation No. 2 of Example 3 (Table II) and, as such, includes on a solid basis 39.6 wt. % SLES, 64.3% of the nonionic surfactant and 6.1% of a commercial diethanolamide. The preparation of the nonionic surfactants is given in Example 2. As can be noted from the drawing, the viscosity of the aqueous system is primarily dependent upon the nature of the nonionic surfactant and the percent of total solids in the system. As shown, the greatest build-up of viscosity can be achieved by using the 82-mole polyoxyalkylene adduct of an equilibrated reaction mixture of mono- and diglycerides derived from tallow wherein the polyoxyalkylene chain is composed of randomly distributed oxyethylene and oxypropylene residues in the ratio of 3:1 respectively. On the other hand, substituting a similar 35-mole oxyalkylene adduct of a comparable partial ester mixture of coconut fatty acids therefore permits higher solids levels in obtaining the corresponding viscosity of the use of said tallowate adduct. Further, it can be seen that control of the viscosity characteristics ca be realized within the normal range of solids concentration of a detergent system by judiciously blending these two representative partial glycerol ester adducts. Example 3 (Table II) illustrates the low degree of eye irritation associated with typical detergent shampoo systems based on mixed propylene/ethylene alkoxylates. WHAT WE CLAIM IS:

1. A detergent composition having an active content comprising: a) an alkylene oxide adduct of a partial glycerol ester of a fatty acid having 10 to 18 carbon atoms, the partial glycerol ester having a monoglyceride content of from 15 to 45% by weight with the balance essentially consisting of digylceride, the adduct having been prepared by reacting the partial glycerol ester with ethylene oxide, propylene oxide or a mixture thereof in which the molar ratio of ethylene oxide to propylene oxide is from 2:1 to 4.5:1, in a molar ratio of partial glycerol ester to alkylene oxide of from 1:15 to 1:100, and b) an anionic surface active agent which is a salt of a higher alkyl sulphate, a salt of a higher alkyl ether sulphate, a salt or a higher alkyl benzene sulphonate or any combination thereof, the weight ratio of component a) to component b) being from 1:1 to 4:1.

2. A detergent composition as claimed in Claim 1 in which the ratio of component a) to component b) is from 2:1 to 5:1.

3. A detergent composition as claimed in Claim 1 or Claim 2 which additionally comprises: c) a foam stabilizing agent which is an alkanolamide, a tertiary amine oxide or a mixture thereof, the ratio of component b) to component c) being from 4:1 to 5:1.

4. A detergent composition as claimed in any preceding claim in which the anionic surface active agent is sodium lauryl sulphate, sodium lauryl ether sulphate or a sodium alkyl benzene sulphonate in which the alkyl group contains 12 to 18 carbon atoms.

5. A detergent composition as claimed in Claim 1 substantially as herein described with reference to any one of the Examples.

6. A detergent composition as claimed in Claim 1 substantially as herein described with reference to Figure 3 of the accompanying drawings.