Detergent bar made from mixed fatty acid derivatives
United States Patent Gatti et al.  
 [ Apr. 22, 1975 DETERGENT BAR MADE FROM MIXED FATTY ACID DERIVATIVES lnventors: Louis Gatti, 1415 Graymill Dr.,  
 Scotch Plains, NJ. 07090; Raymond George Matthaei, 35-03 Van Duren Ave., Fair Lawn, NJ. 07410 Filed: Jan. 17, 1973 Appl. No: 324,459  
 [56] References Cited UNITED STATES PATENTS 3,730,912 5/1973 lnamorato 252/121 X OTHER PUBUICATIONS McBride. Chemical &amp; Metallurgical Engineering, Dec. 1940, PP. 830 to 833 (TN 1 M5). 1  
 Primary E.\&#39;aminerLe1and A. Sebastian Attorney, Agent, or Firm-Arnold Grant, Esq.  
 1 5 7 1 ABSTRACT Mixtures of acyl isethionates of selected critical chain lengths exhibit superior lathering properties when incorporated into a detergent toilet bar.  
 4 Claims, No Drawings DETERGENT BAR MADE FROM MIXED FATTY ACID DERIVATIVES BACKGROUND OF THE INVENTION 1. Field of the Invention Detergent toilet bars containing acyl isethionates have been known for many years. For example Nuesslein in U.S. Pat. No. 1,906,484 discloses an alkalimetal soap, and specifically sodium palmitate, containing admixed therewith from 5 to l000%, soap basis, of an acyl isethionate of vegetable origin.  
  A commercially successful bar is described and claimed in U.S. Pat. No. 2,894,912 to Geitz. However this bar is relatively expensive to manufacture, and it is evident that the discovery of a procedure for making a less expensive bar without sacrificing quality would be highly desirable.  
  2. The Prior Art U.S. Pat. No. 1,906,484 to Nuesslein The most pertinent disclosure in this patent is Example 3, wherein there is set forth a mixture of 80 parts oleic isethionate, 15 parts of sodium palmitate, and 5 parts of sodium perborate.  
 U.S. Pat. No. 2,749,315 to Faier Discloses a process for making a bar having a major amount of anhydrous, water-soluble soap, and a minor amount of mixed water-soluble synthetic detergents comprising a mixture of higher fatty acid monoglyceride monosulfates and higher fatty acid amide of aminomethanesulfonates.  
 U.S. Pat. No. 2,781,321 to Mayhew et a1 diisopropyl Relates to a bar containing a detergent, e.g., Na oleic isethionate, a plasticizer, e.g., calcium stearate, and a lathering agent, e.g. Na diisorpropyl naphthalenesulfonate.  
 U.S. Pat. No. 2,894,912 to Geitz Discloses a bar having 30 to 70% of an acyl isethionate, at least 75% of the acyl groups having 12-18 carbon atoms and up to 25% having 6-10 carbon atoms, up to 25% soap, to 40% fatty acid, up to 9% water, 2 -10% of a suds-boosting detergent, the bar having a pH of 6 to 8 measured as a 10% aqueous solution at 35C.  
 US Pat. No. 3,420,857 to Holland et a1 Relates to a step in the process for reacting a fatty acid with sodium isethionate comprising continuously replacing the fatty acids volatilized during the course of the reaction with fatty acids having a composition corresponding to that of the volatilized fatty acids. U.S. Pat. No. 3,420,858 to McCrimlisk Relates to a two-step vacuum stripping operation in a process for reacting a fatty acid with sodium isethionate. U.S. Pat. No. 3,607,761 to Feighner et a1 Relates to soaps containing soaps prepared from C -C acids derived from the oxidation of alcohols produced by the Guerbet reaction.  
 SUMMARY OF THE INVENTION It has now been discovered that the lathering properties of a toilet detergent bar, wherein the major surfaceactive detergent component is an acyl isethionate, are improved, or the same lathering as heretofore can be obtained with less active detergent, when the acyl portion of the acyl isethionate is a mixture derived from fatty acids of critical chain length.  
  Accordingly it is an object of the present invention to provide a toilet detergent bar having improved lathering properties.  
  It is another object of the invention to provide a fatty acid mixture adapted to be esterified with an alkalimetal isethionate to produce a mixture of alkali-metal acyl isethionates having the chain-length distribution of said mixture, and having superior lathering properties when formulated into a toilet bar for cleansing the skin.  
  Therefore the invention concerns a toilet detergent bar having as its major detergent active a mixture of acyl isethionates wherein the acyl portion is derived from fatty acids of mixed selected critical chain lengths and has substantially the chain-length distribution of said fatty acids.  
  In a broader aspect the invention relates to a fatty acid mixture having critical proportions of selected chain lengths and being capable of esterification with isethionic acid to form a mixture of acyl isethionates having superior lathering properties.  
  In another aspect the invention relates to a mixture of acyl isethionates having superior latherin g properties when formulated into a toilet detergent bar.  
  By the term superior lathering properties is meant the ability to produce at a lower acyl isethionate content the same lather volume as prior-art acyl isethionate bars, as well as more lather at the same active detergent content.  
  The fatty acyl portion of the fatty acyl isethionate must be selected critically to obtain the improved sudsing characteristics of the products of the present invention. The invention contemplates the use of acyl isethionates wherein the fatty acyl portion comprises about 28-37% C about 18-24% C about 16-21% C about 9-20% C and about 10-1 7% C chain lengths.  
  The preferred ranges of acyl chain lengths are about 32-34% C (decanoyl), about 20-23% C (dodecanoyl), about 18-20% C (tetra.decanoyl), about 12-16% C ,,(hexadecanoyl), and about 1 1-14% C (octadecanoyl), chain lengths. The foregoing proportions are based on the total fatty acids. combined as isethionate.  
  The fatty acids contemplated for use in the practice of this invention are unbranched and saturated, and may be derived from natural fats, such as coconut oil, palm kernel oil, tallow, hydrogenated vegetable oils, etc., or may be prepared synthetically.  
 MANUFACTURE OF THE ACYL ISETHIONATE The acyl isethionate found useful in accordance with the present invention is prepared by the general procedure described in Holland et a1, U.S. Pat. No. 3,420,857, and McCrimlisk U.S. Pat. No. 3,420,858, both assigned to the instant assignee. In these patents there are described procedures whereby, in the esterification of sodium isethionate with fatty acids having a range of chain lengths, there is avoided any substantial enrichment of the esters in the higher molecular weight acyl portion of the molecule due to volatilization of the lower molecular weight fatty acids. This is accomplished by continuously supplying to the reaction mass fatty acid reactants of a composition corresponding to fatty acids volatizlied during the course of the reaction. Moreover when excess fatty acid reactant is stripped from the reaction mass, stearic acid, which is a component of the bar to be formulated from the acyl isethionate, is added to the mass to retain fluidity. If the stearic acid is added at the start of the stripping operation a portion of this acid reacts with free sodium isethionate since at this point the esterification reaction is still proceeding. This results in lowering the proportion of the desirable low molecular weight acyl isethionates. To minimize this, the early stage of the step is conducted under vacuum to remove as much of the lights as possible and when lack of fluidity due to depletion of the free fatty content becomes a problem, stearic acid is added to restore fluidity. By delaying the addition of stearic acid, less of the undesirable high molecular weight acyl isethionates are formed than would be formed if the stearic acid were added at the start of the stripping step.  
  The use of the critical fatty acid mixture for preparing the more efficient acyl isethionate in accordance with the invention has-the advantage of economy of manufacture due primarily to the fact that the reaction between sodium isethionate and fatty acids need proceed only to the point of attaining 67% active detergent acyl isethionate in the reaction mass rather than 75-85% as in the Holland et a1 process described in US. Pat. No. 3,420,857, this process being representative of the prior-art commercial process. Moreover the absence of the lower molecular weight fatty acids in the process of the instant invention lessens the stripping time. It is estimated that the reaction time for the preparation of acyl isethionate from the critical fatty acid mixture of the instant invention is only about one-half that by prior-art procedures.  
 THE LATHERING TEST Twenty women constituting a test panel are-provided with detergent or soap bars to be tested and requested to wash their hands in their own customary manner and to make a judgment of the comparative lathering properties of the bar. Only two bars are tested at one time.  
 THE WEAR-RATE TEST This test determines the weight loss of a detergent or soap bar which has been washed in a standardized manner and allowed to remain in an undrained soap dish between uses.  
  To determine wear rate, initial and final weights of a bar are made in a partially wet state, the test being conducted in the following manner. A bar is submerged in the hands in /2 gallon of water at 105F having a desired hardness in a l-gallon container. The bar is-removed and rotated in the hands 20.times through 180. The bar is again submerged in the same water, removed, and rotated 20 times as before. The bar is sub- 5 merged a third time in the water, removed, and carefully contacted with terry towelling to remove adhering water. The bar is then weighed, and placed in a conventional flat bottom soap dish containing water at 80F;  
  6.5 ml of water for a regular size bar, and 7.5 ml for a 0 bath-size bar. The foregoing is carried out as early in the day as is practical. At equally spaced-apart intervals throughout the day, the abovedescribed dual handwashing steps are repeated three times, the bar being placed in the water-containing dish after the second wash of each of the dual washing steps. On the second day, as early as practical, the bar is removed from the dish and a dual wash step made as before, following which the bar is again contacted with terry towelling to remove adhering water, and again weighed. The difference in weights divided by the number of washes conductedis the weight loss per wash.  
  The invention may be more readily understood by reference to the following Examples which are illustrative, but are not to be considered limitative, of the invention.  
 EXAMPLE I This example shows the effect of varying the chainlength distribution of the acyl isethionates on lathering .and. wear rate of toilet detergent bars prepared therefrom.  
  Sodium acyl isethionates are prepared from a mixture of 50% C 25% C and 25% C saturated fatty acids. A separate batch is prepared from commercial triple pressed stearic acid, consisting of about 55% hexadecanoic and about 45% octadecanoic acids. A control batch is prepared from partially hydrogenated coconut oil fatty acids. Each batch is fluidized with the aforementioned triple pressed stearic acid, the batches being prepared in general by the process of Holland et al described in US. Pat. No. 3,420,857, to form a mixture of sodium acyl isethionates and free fatty acids.  
  The compositions of the bars are shown in Table I and the fatty acid distribution of the acyl isethionates and the free fatty acids in the mixture prepared as above are given in Table II.  
 TABLE 1 BAR COMPOSITIONS Composition No. 1. 2. 3 4.  
 Na acyl isethionate from par- 49.80  
  tially hydrogenated mixcd coconut oil fatty acids Na acyl isethionate from C 31.00 33.00 35.00  
  C and C fatty acids Na acyl isethionate from C 10.00 8.00 6.00  
  and C fatty acids Na dodecylbenzenesulfonate 2.02 2.02 2.02 2.02 Na tallow soap 6.66 8.66 8.66 8.66 Na coconut oil soap 1.66 2.16 2.16 2.16 Na stearate 2.98 2.98 2.98 2.98 Na isethionate 4.78 4.78 4.78 4.78 Free fatty acid 23.23 30.73 30.73 30.73 NaCl 0.35 0.35 0.35 0.35 Misc. extraneous matter associ- 3.27 2.07 2.07 2.18  
  ated with the components Water 5.25 5.25 5.25 5% 100.00 100.00 100.00 100.00 Fatty Acid Distribution C 3.0 none none none C 5.0 31.0 33.0 35.0 C 45.0 20.0 21.2, 22.5 C 18.0 18.2 19.4 20.6 C 14.0 16.7 14.2 11.7 C 10.0 14.1 12.2 10.2 C (olcic acid) 5.0 none none none TABLE II FATTY ACID DISTRIBUTION ACYL ISETHIONATES EXAMPLE 3 The mixedacyl isethionates prepared as in Example 2 are formulated into toilet detergent bars containing From partially 45% of the acyl isethionate, and 26.73% free fatty acid, ggg ii gfg F Curb bf gg g 5 the balance of the compositions being the same as in acid (control) Fatty Acids Stearic Acid bars 2 an 3 f Table I.  
 go EXAMPLE 4 C7,, 5:0 41.0 1O Acyl isethionate mixtures having the acyl distribution 13:8 gi of composition in Table III, Example 2, are formu- C,, 14.0 4. 1 55.0 lated into toilet detergent bars at levels of 25 and 60%, 5: 2 2 in conjunction with three supplemental detergents, namely, sodium lauryl sulfate, sodium alkyl benzene- C Free Fatty Acid sulfonate wherein the alkyl group has about 13 carbon 6: I atoms, and the fatty acid amides of N-methyl taurine, C 2.1 130 wherein the fatty acid portion is derived from coconut 38 gig oil. The compositions are shown in Table IV. C, 25.0 25.3 55.0 2:. 2:2 2:2 2 TABLEW C20 0.7 0.1  
  The following are illustrative of the toilet bar &#34;inti&#39;oduced intotheacyl isethionate molecule by reaction with the C C,,, fatty compositions within the present invention acids used for fluidizing. PERCENT Composition No. l 2 3 4 5 6 Wear rate and lathermg properties of the bars are dey isethionatem 25 25 25 60 60 60 termined by methods described elsewhere herein. Na who, soap 25 20 18 5 5 3 A slight decrease in wear rate and a slight decrease Stearic acid 40 38 36 15 15 10 in lather volume are noted as the proportion of 1C and E: g:gl; ggf &#39;6 C isethionate is increased in the foregoing series. All lf t three compositions however by statistical analysis are Na coco 10 7 N-methyl taurine udged to be substantially equal to control bar No. l in Na Steam: 3 3 3 3 3 3 these properties. Na isethionate 4 4 4 4 4 4 The evaluation clearly shows the advantages of em- 1 x3223; d 2 2 2 3 3 3 ploying the selected mixture of acyl isethionate chain with the components lengths within the instant invention, 1.e., substantially g g g Perfume g g g u g g the same lathering and rate of wear as are characteris- 100 100 100 100 00 100 tic of acyl isethionate bars heretofore known can be ob- W tained at a lower acyl isethionate content with the bars 123331,25553235315393)tg&#39;gitgfggglf of the invention, along with the processing advantages hereinbefore described. Within the broader percentage ranges of acyl isethionate chain lengths set forth herein Having described the invention, many difi ti there are insignificant decreases in lather Volume and will occur to those skilled in the art and the invention improvements in wearing quality as the proportions of is to be limited only by the Scope of the appended the higher molecular weight acyl isethionates are inchime creased. What is claimed is:  
  1. A mixture of fatty acids comprising about 28 to EXAMPLE 2 about 37% decanoic acid, about 18 to about 24% MiXinl&#39;eS 0f fatty acids of Varying chain lengths are dodecanoic acid, about 16 to about 21% tetradecanoic prepared and reacted with sodium isethionate in accoracid, about 9 to about 20% hexadeoanoic id and dance with the procedures of Holland et al. and about 10 to about 17% ootadeoauoic acid, id McCrimlisk described hereinbefore. The chain-length centages being on the total fatty acid basis, and said distributions of the acyl portions of the acyl isethionmixture being adaptable for use in the preparation of ates resulting from the procedure are shown below in an acyl isethionate mixture having superior lathering Table III, and further illustrate the variations contemproperties. plated within the instant invention. 2. A sodium acyl isethionate mixture having mixed The composition distributions are expressed in peracyl groups of 10, 12, l4, l6, and 18 carbon atoms, said cent fatty acids, based on the total of the fatty acids acyl groups having the molecular weight distribution of combined as acyl isethionates. the fatty acid composition of claim 1.  
 TABLE &#39;III PERCENT Composition No. 5 6 7 8 9 l0 l 1 l2 l3 Decanoyl 28 29 30 32 32 33 34 35 37 Dodccanoyl 23 23 22 21 23 24 20 23 18 Tctradccanoyl 19 2O 19 21 l8 18 2O l7 l6 Hcxadecanoyl 20 l 1 l4 l4 l6 1 l 12 9 l9 Octadecanoyl i0 17 15 12 ll l4 l4 l6 10 100 100 I00 100 lOO 100 I00 lOO 3. A detergent bar comprising from about 25 to about 60% of a water-soluble alkali-metal detergent salt of an ester of isethionic acid with mixed aliphatic fatty acids having from 10 to 18 carbon atoms and an iodine value of 0 to about 1, said mixture of fatty acids comprising about 28 to 37% decanoic, about 18 to 24% dodecanoic, about 16 to 21% tetradecanoic, about 9 to hexadecanoic, and about 10 to 17% octadecanoic acids, total esterified acid basis, from O to about 10% of at least one water-soluble suds-boosting detergent salt selected from the group consisting of alkali metal and organic amine higher aliphatic fatty alcohol sulfates, alkyl aryl sulfonates, and higher aliphatic fatty acid taurides, from about 1 to about 9% water, from about 2.5 to about 25% of water-soluble higher fatty acid soap, and from 10 to 40% of at least one higher fatty acid having from about 12 to about 25 carbon atoms as a binder and plasticizer, said bar having a pH within the range from 6 to 8, measured as a 10% aqueous solution of the bar composition at 35C.  
  4. A mixture of saturated fatty acids wherein decanoic acid is present in the proportion of about 50%, dodecanoic acid is present in the proportion of about 25%, and tetradecanoic acid is present in the proportion of about 25%, basis by weight of said mixture.  
  UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIQN PATENT NO. 3, 879,309  
 DATED April 22, 1975 |NVENTOR(S) Louis Gatti and Raymond George Matthaei It is certified that error appears in the aboveidentified patent and that said Letters Patent are hereby corrected as shown below:  
  Under the heading of the Title Page, an Assignee should be included as follows:  
 Assignee: Lever Brothers Company, New York, N.Y.  
 gigned and eaied this fif Day Of August1975 [SEAL] A ttest:  
 RUTH C. MASON v C. MARSHALL DANN Arresting Officer (unmiirsi&#39;mwr uflau&#39;nls and Trmlvmarks UNITED STATES PATENT OFFICE QETTTTCATE QT CGREQTTN PATENT NO. 1 3,879,309  
 DATED April 22, 1975 INVENTOR(S) Louis Gatti and Raymond George Matthaei It is certified that error appears in the ab0veidentitied patent and that said Letters Patent are hereby corrected as shown below:  
  Under the heading of the Title Page, an Assignee should be included as follows:  
 Assignee: Lever Brothers Company, New York, N.Y.  
  fif 3y 6f August1975 [SEAL] Arrest.-  
 RUTH C. MASON C. MARSHALL DANN Arresting Officer (ummr&#39;ssimu&#39;r nj&#39;laronls and Trademarks