CA2007911A1 - Synthetic detergent bars - Google Patents

Abstract

A synthetic detergent bar containing a lime soap dispersant such as sodium cocyl isethionate and an amount of sodium bicarbonate effective to slow the rate of dissolution of the bar in water, the bar having a water content of from about 3.5 to about 8%, by weight of the bar. The bar is especially suitable for incorporation in a spongelike article, for use in cleaning hard surfaces such as dishes and, depending on the texture of the substrate, in bathing.

Description

tr," ~ .

f~ ~ DR-5186 20~)7~1 SYhln~llC DETERGENT aARS

by Frank J. Steer and Edmund D. George Field o~ Invention The present invention concerns slowly dissolving synthetic detergent bar8. In particular, the present invention concerns the incorporation of sodium bicarbonate as a dissolution retarding agent in sUCh synthetiC detergent bar articles. The present invention especially concerns a scrubbing article comprising a porous 5ubstrate containing the synthetic detergent bar of the present invention.

Bac~LG~I~ o~ Invention Synthetic detergent bars (i.e., Nsyndet" bars) are well known. For example, U.S. 3,376,229 to Haass, et al. discloses syndet bars containing acyl isethionate as the principal deter-gent component together with supplemental detergent, binder and . _~

plastizer components. Up to about 17% unesterified watersoluble alkali metal isethlonate i8 incorporated in the bar of Haass, et al., apparently to improve firmne88. The supplemental detergents include the higher aliphatie alcohol sulfates, the alkylaryl sulfonate8, and the higher aliphatic fatty acid taurides. Binder plasticizers include aliphatic carboxylic acids having 12-25 carbons and polyethylene glycols Bar hardness may be increased by incorporating sodium chloride.

U.S. 2,177,055 to Cranor discloses a toilet soap composition containing, in addition to the soap constituent, a relatively large quantity of biearbonate of soda, the resulting composition being effective in neutralizing odors of perspiration. Although as little as 5~ bicarbonate is 8tated as having a deodorant effect, Cranor indicate8 that for praetical purposes 10 to 90 parts bicarbonate shoUld be incorporated into the soap composition.

U.S. 3,956,160 to Watanabe, et al. discloses a detergent powder containing a powdered hydrous sodium carbonate and a fatty acid at a mole ratio of 1-1.5 mol carbonate per mol fatty acid. The powdered sodium carbonate includes sodium sesquicarbonate (Na2C03 NaHC03 2H20) and mixtures of sodium carbonate and sodium bicarbonate. The carbonate and zoa7sl~.

fatty acid react when at a temperature above the meltlng point of the acld, to produce a coarge soap that may be disintegrated into a detergent powder.

skin-conditioning toilet 80ap bars are disclosed in U.S.
4,198,311 to France, et al., wherein the soap is a coco/tallow blend and the bar also includes an anionic surfactant such as an olefin sulfonate and fatty acid ester of sodium isethionate.

Soap composition~ containing an alkali metal C8-~18 acyl isethionate are disclosed in U.S- 4,695,395 to Caswell, et al.
Antimicrobial toilet bars are disclosed in U.S. 4,714,563 to Ra~s, et al.

A long-lastlng detergent bar i8 disclosed in U.S. 4,735,746 to Speranza, et al- wherein a water-soluble polyamide or polyester i8 prepared or melted in the presence of a surface-actiVe agent- Solid transparent cleansers are disclosed in Gordon, U.S. 4,165,293.

Soaps capable of dispensing lime soap are disclosed in U.S.
3,850,834 to Hellsten, et al. See also U.S. 3,630,927 to Yo Shen; U.S. 3,640,882 to Groves; 3,767,584 to Hirst: 4,000,081 to Woo, et al; 3,793,215 to Smith and 3,988,255 to Seiden, each of these patents being incorporated herein by reference thereto.

~ 2~)7911 Although the solubillty characteric~ of syndQt bars such as disclosed by Haa88 are generally ~uitable, 8yndet bars for some uses tend to be too quickly di9solving. Thu8, where water con-tact with the bar tends to be prolonged, it i8 necessary to have a bar that re~ists rapid dls801ution. Also, syndet bars which ~ay lie in water have a tendency to form a gel-like scum at the bar surface that i5 in contact with water, which is not par-ticularly attractive to consumers.

It has been found that the dissolution characteristics of syndet bars can be improved by incorporating therein from above about 5 to about 30% sodium bicarbonate. The synthetic deter-gent or syndet bars of the present invention advantageously have a ~low diRsolution rate when in contact with water. Moreover, the bars herein have good foam generation characterictics and good resistance to hard water film formation. Further, the syndet bars of the present invention are mild to the skin, especially important for hard and soft surface cleaning applications where skin contact is likely. The syndet bars are easily and inexpensively manufactured utilizing conventional soap bar manufacturing apparatus and processes.

Z(~ 911 ~?

Summary of the Invention It is an ob~ect of the present invention to provide a syn-thetic detergent or 8yndet bar that resi8t8 rapid dissolution, yet forms a suitable amount of suds when immersed in water ~ t is another ob~ect of the invention to provide a syndet bar that has a long length of life.

It is yet another ob~ect of the present invention to provide a syndet bar that resists cracking.

Another aspect of the present invention i8 to incorporate the syndet bar of the present invention into a scrubbing device.

The syndet bar of the present invention comprises from about 20 to about 90% of a particular synthetic detergent known in the art as a lime 80ap disper8ant and up to about 30% sodium bicarbonate, the amount of bicarbonate present in the bar being effective to retard the dissolution rate of the bar and preferably being from about 10 to about 20% by weight of the bar. Preferably, the lime soap dispersant detergent is from about 30 to about 50% by weight of the bar, and is selected from the group consi8ting of sodium cocoyl isethionate and disodium lauryl sulfosuccinate. The moisture content of the bars is from 2Q~)7911.

about 3.5 to about 8%. Other con8tituents may be lncorporated a~ hereinafter described.

The syndet bar8 of the present invention may also contaln up to about 40% of a fatty acid; other detergents that are not lime soap dispersant8, typically in amounts of less than 50%; up to about 15% alXali metal salt of a fatty acid, i.e., soap, and one or more ad~uvant8 in amount8 effective to achieve their ~unctional purpose.

The bars of the present invention may be prepared by extrusion and melt casting methods.

Brief Description of the Drawings Figure 1 is a 8crubbing article in accordance with the present invention, a portion of which has been broken away to illustrate its interior structure.

Figure 2 is an alternate embodiment of the scrubbing article of the present invention, in broken-away perspective view.

2Q3791~.
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Detailed Description of The Preferred Embodiment The synthetic detergent or 8yndet bar of the present inven-tion advantageOU81Y has a very slow rate of dissolution in water. On the other hand, the syndet bars herein have good foam generatiOn characteristics, offer good resistance to the formation of scum in the presence of hard water, and are mild to the skin. Thus, the 8yndet bars are useful as skin cleanslng bars. In such utility the tendency of syndet bars to form a gel-like film or 8cum at the water-soap interface when in contact with water i5 greatly reduced The syndet bar8 of the present invention, however, are particularly useful for incorporation in scrubbing articles, such as ~crubbing articles di8closed in U.S. Patents 4,240,760 to Levine; 3,581,447 to Falivene: 4,665,580 to Morris; 4,510,641 to Morris; 4,674,237 to Sullivan; 4,190,550 to Campbell;
4,457,640 to Anderson, 4,659,496 to Klemm, et al. and 4,062,792 to ~cNabb, each of which is incorporated herein by reference thereto.

A particularly preferred substrate for use ~n accordance with the present invention ig the product LEM-METM sold by swiss-Tex~ Inc. of Greenville, South Carolina. The LEM-METM

- - - - - -~ ~ 20~79~ ~

article is of the type 8hown in Figure 2, hereinafter described. The bar contained in the LEM-MET~ substrate is a soap bar of conventional composition and doe~ not contain sodium bicarbonate. The use-up rate of the soap bar contained in the LEM-METM article was faster than desirable.

Such scrubbing articles are useful, for example, for washing hard surfaces 8uch a8 countertops and dishes and soft surfaces, e.g., as abrasive skin cleansers. These articles generally comprise reticulated foam 8ub8trates of the same or different texture ~oined at their edges in 8uch manner as to form an interior pocket in which the 8yndet bar lies. These articles are immersed periodically in water and may remain in water contact, for example, in the 8ink or bathtub, for some time.
Even after u8e, thQ 80ap bar contained in the article is wetted by the residual water trapped in the pores of the sponge-like substrate. Accordingly, it i8 very important for the syndet bar contained within the substrate to have a reasonable life. In this regard, syndet bars of the present invention are quite suitable. In addition, when the surface of the bar is in contact with water, a8 when the scrubbing article is placed in water or on a sinktop after use, there i8 reduced tendency for the bar to become 80ft and mushy- Of course, these properties are also advantageous in other products.

, ~ f~ 2Q~)7911.

g Merely by way o~ illu8tratlon, a Bcrubbing article in accord-ance with the present lnvention iQ illustrated in Flgure 1.

The ~crubbing article 10 compri8es a first reticulated laminate 12 and a 8econd reticulated laminate 14, which lami-nates 12 and 14 are affixed at seam 16, for example, by heat sealing or by other conventional means. As seen in the broken-aWay Bection, the interior of the article 10 is hollow, a pocket 26 being formed, which pocket 26 accommodates the syndet bar 30 of the present invention.

As indicated by the cros8-hatching or side walls 22 and 24 of the laminates 12 and 14, respectively, the laminates may be ~ade from different materials having different textures. Thus, laminate 12 i8 Bmooth, which laminate 14 is more abrasive. The thickness of the wallB 22 and 24 may be the same or different.
Suitable materialB for the lamlnate8 12 and 14 are cellular porous materials that can be glued, sewn or heat sealed, such as polyester, polyester-polyurethane, polyurethane esters, cellu-lose foam, paper, rayon, nylon, cotton, wool, polyolefins and t`he like.

Preferred laminate material8 are polyester-polyurethane and polyurethane esters.

2~)791~.

In another embodlment, shown in Figure 2, the article 100 nay comprise a third laminate 118 positioned within the article 100, to form a first pocket 126 and a seCond pocket 128, the detergent bar 130 being placed within the pocket 126. In this embodiment, the laminate 114 is quite porous. It is also very abrasive, and eminently suitable for hard-to-clean surfaces.
The laminate 112 in this embodiment is smoother and tends to be less porous. Because it i8 porous, there is a tendency for the detergent solUtiOn to pass through the laminate 114 easily.
Accordingly, a barrier laminate 118 iB provided. The laminate 118 is typically of the same material as the laminate 112, although usually thinner- In this manner the rapid diffusion of detergent solution through the laminate 114 is avoided.

The syndet bar of the present invention comprises by weight of the bar at least one synthetic detergent constituent that is a lime soap dispersant and which i8 present in an amount effective to provide cleaning, broadly from about 20 to about 90%, preferably from about 30 to about 50%, and preferably from about 10 to about 20% ~odium bicarbonate, although up to about 30% can be incorporated. Although the reason is not well understood, the presence of the bicarbonate in the syndet bar reduces its rate of dissolution- Moreover, there is less of a X(~)791~.

tendency of the bar to become soft, e8pecially where the surface of the bar ls in contact with water. These attrlbutes might be realized wlth as little as about 5% sodium bicarbonate, by weight of the bar. However, preferably about 10% sodium bicarbonate should be incorporated ln the bars of the present invention.

Among the lime soap dispersant that may be incorporated in the soap bars of the present invention are the neutrali2ed fatty acid esters of isethionic acid and fatty acid half esters of succinic acid. Preferred lime soap dispersants include 60dium cocoyl isethionate and di80dium lauryl sulfosuccinate.
IllustratiVe of the isethionate are Jordapon CI, an 83% active sodium cocoyl isethionate manufactured by PPG/Mazur Chemical Co., and Isepon AC-78 manufactured by GAF Chemicals Corp.
Representative of the sulfo8uccinate half e8ters are Emcol 4300 manufactured by Witco Chemical Co. and Monamate LA-lO0 made by Mona Industries, Inc.

Lime soap dispersants have superior tolerance to hard water, and therefore are less likely to form a soap scum or residue.
These surfactants are good grease cutters, and hence the bars of the present invention may be employed in scrubbing articles intended for hard surface cleaning, especially dishes. These 7~911 (~ ~

surfactants are al80 mlld to the 8kin, and hence are eminently suitable for ~uch utilities as dish cleaner~, loofahs~ and the like. Finally, the8e material8 are available in solid form, and hence are usable in extru8ion processe8, which is the preferred manufacturing method.

Other synthetic detergent may be incorporated in the syndet bar of the present invention to improve detergency and increase foaming.

The anionic surfactants are typically water-soluble alkyl or alkylaryl compounds, the alkyl having from about 8 to about 22 carbons, including generally a sulfate or sulfonate substituent group that has been base-neutralized, typically to provide an alkali metal, e.g., sodium or potassium, or an ammonium anion, including, for example: (1) alkyl and alkylaryl sulfates and sulfonates having preferably 10 to 18 carbon~ in the alkyl group, which may be straight or branched chain, e.g., sodium lauryl sulfate and sodium dodecylbenzene 8ulfonate; (2) alphaolefin aryl sulfonates preferably having from about 10 to 18 carbons in the olefin, e.g., 50dium C14_16 olefin 8ulfonate, which is a ~ixture of long-chain sulfonate 8alt8 prepared by sulfonation of C14-C16 alpha-olefin9 and chiefly comprlsing sodium alkene sulfonate9 and sodium hydroxyalkane 8ulfonates; (3) sulfated and - - .

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sulfonated monoglycerides, e8pecially tho8e derived from coconut oil fatty acid8; (4) sul~ate e8ter8 of (a) ethoxylated fatty alcohols having 1-10 mol~ ethylene oxide, e.g., sodium polyoxyethylene (7 mols E0) lauryl ether 8ulfate, and (b) of ethoxylated alkyl phenol8 having 10 mol8 ethylene oxide and 8 to 12 carbons in the alkyl, e-g-, ammonium polyoxyethylene (4 mols E0) nonyl phenol ether 8ulfate; (5) fatty acid amides of a methyl tauride, e.g., 60dium methyl cocoyl taurate, (6) B-acetoxy- or B-acetamido-alkane sulfonates where the alkane has from 8 to 22 carbon8, and (7) C8-C13 ~arCOsinates~ e.g., sodium lauroyl sarcosinate.

Nonionics such a8 (1) fatty alcohol alkoxylates, especially the ethoxylates, wherein the alkyl group has from 8 to 22, preferably 12 to 18, carbon8, and typically 6 to 15 mols alkoxide per molecule, e.g., coconut alcohol condensed with about 9 mols ethylene oxide; (2) fatty acid alkoxylate8 having from about 6 to about 15 mols alkoxylate, especially the ethoxylate; (3) alkyl-phenoxy alkoxylates, especially the ethoxylates, preferably the octyl or nonyl ethoxylates containing 6 to 12 carbons in the alkyl, and having about 5 to 25, preferably 5 to 15 mols alkylene oxide per molecule, e.q., nonyl phenol ethoxylated with about 9.5 mols ethylene oxide (Igepal C0-630); (4) condensates of ethylene oxide with a hydrophobic base formed by condensation of ZQ~9~

propyleneoxide with propylenQ glycol, e.g., nonionic surfactants of the Pluronic 8erie8 manufactured by BASF Wyandotte, (5) condensates of ethylene oxide with an amine or amide; (6) fatty amine oxides, e.g., stearyl dimethyl amine oxlde, and (7) alkylolamides.

Preferred anionics are the alkyl and alkylaryl sulfates and the alpha-olefin aryl sulfonate8, while preferred nonionics are the fatty alcohol ethoxylates and the alkyl phenoxy ethoxylates.

These other synthetiC deter~ents are included in an amount of up to about 50% by weight of the 8yndet bar, preferably from about 1 to about 20% of the bar, most especially from about 1 to about 10% by weight of the bar.

The syndet bar of the present invention ~ay also include other constituent8. For example, the syndet bar may include nonsyndet surface-active agents in minor amounts- Most important of these constituents are the alkali metal soaps, especially soaps from fatty acids having from about 12 to about 18 carbons.
Usually this component is present in an amount of less than 25%, preferably between about 5 to about 15%. More than one soap constituent may be present. Suitable is a mixture of 0-50% coco and 50-100% tallow soapg, especially mixture5 of 10-25% coco and ~, ~) 2~ 9~1 75-90% tallow ~oaps. Soaps are employed to modify the physical properties of the bar, without detracting from its intended function. Thus, increa51ng the level of tallow 80ap present ln the bar will increase the bar's hardness resulting in a more slowly dissolving bar- Analogously, increasing the coco soap level provides a softer, more easily dissolved bar. A 15/85 coco/tallow mixture represent8 a preferred blend to provide an optimum balance among the several important physical properties.

Another optional constituent is a binder in the form of a waxy and generally water-insoluble material. Preferably, the binder is extrudable and present in an amount of from O to about 50% by weight of the bar. The preferred level is from about 10 to about 40% by weight- The binder is for example a fatty acid, especiallY stearic acid- Because the fatty acid ig a weak acid, it does not react with the bicarbonate, a weak base, at the moisture level present in the bar. Other suitable binders include glycol esters of fatty acids and amides of fatty acids.
HydroxypropylmethYl cellulose and microcrystalline cellulose may be used as binders and/or solubility control agents.

The bar may also contain one or more inorganic fillers, for example, sodium chloride, in an amount of from O to about 5% by weight, preferably between 0.1-1% by weight. It is believed that -~ ~ 2~7911.

sodium chloride, pos8ibility because it i8 an electrolyte, plays a role in the con8istency and/or proce8sabillty of the syndet bar.

Another optional constituent i8 sodium i5ethionate in an amount under about 5%. Thi8 material ig believed to aid in bar firmness as indicated in the aforementioned ~aass patent.

The bar of the present invention may also contain a chelating of sequestering agent, for example, ethylene diamine-tetraacetic acid (EDTA). The chelating/sequestering agent is present in an amount effective to tie up hardness ions -- calcium and magnesium. A polyacrylic re8in may also be incorporated for this purpose. Usually, the amount contained in the bar i6 from 0.1 to about 5% by weight of the bar, preferably from 0.1 to 2% by weight.

The bar may al80 contain an emollient especially where the bar is intended for use as a skin cleanser. Suitable emollients are PEG-75 Lanolin, isopropyl palmitate, and the like. The emollient may be present in the bar in an amount of up to about 5%. See generally, McCutcheon'8 Functional Materials, p. 140, et seq. (N. Amer. Ed. 1987).

~ r~~ ZQ3791~.

A fragranCQ may be included ln an amount o~ up to about 5%, preferably about 1%, while a dye might be incorporated in small quantity to provide a plea8ant color. Usually, the dye is present in an amount of le88 than 1%, often les~ than 0.1~. A
preservative, e.g., fungicide, germicide, may be present in an amount typically under about 0.5%. An antimicrobial might also be included, especially when the bar is to be employed, say, as a surgical scrub- Mention may be made of hexachlorophene, 3,4,4'-trichlorocarbanilide 801d a8 TCC by Monsanto Co. and substituted diphenyl ethers 8uch a8 Irga6an DP 300 made by Ciba-Geigy Corp. Suitable preservative8 and antimicrobials are well-known in the art. See McCutcheon's, p.11-17.

Water is an e8sential ingredient for several reasons.
First, it has been found that between about 3.5 and about 8%
water content will provide a product consistent with the goals of the present invention. At les8 than about 3.5% water the syndet bar will crumble- At greater than about 8%, the 6yndet bar will lose length of life- Moreover, extrudability of the syndet bar become8 more problematic at the higher water levels.
The bars of the present invention preferably contain from about 5 to about 7% water.

This water content i8 mea8ured a~ free water, i. Q., moisture, preqent in the bar from all source8. Usually, water 2Q~)~911 has to bs added to reach the de81red level. Water content may be measured by a Xarl Fi8her tltration modified ln that the sample is first disper8ed in methanol to extract the water, the filtrate then being titrated- This modification is necessary to remove bicarbonate from the sample, which may cause inaccurate results.

The bar of the present invention may be manufactured in several ways. First, a cast melt proces8 may be used, wherein the ingredients are blended together, heated as to liquefy them, with gentle stirring to provide homogeneity to the mixture, and then poured into a mold- The mold i8 then cooled and the bar released. The variou8 8pecific molding techniques that may be used in the manufacture of the bar8 are well known in the art.

Preferably, however, an extrusion process i8 used. The various ingredient8 except the fragrance and the sodium bicarbonate are preferably admixed to form a dough-like consistency and then flaked in a hot nipped chill roll. The flakes are thereafter combined with the bicarbonate (which may be sensitive to the heat of the flaking operation) and the fragrance oil (which is volatile and preferably in added just prior to extrusion) to form a homogenous extrudable mixture.

~) -- ~ 2(~)79~1.

The homogeneou~ mixture i8 then introduced into the feed hopper o~ an extruder. The barrel temperature varieg usually between 55 and lOO-F. The pre88ure through the forming plate i~ less than 500 psig, generally from about 100 to about 300 psig. The extrudate generally referred to as a billet is cut to the desired size as it leaves the finiæh extruder. As a further step, larger billet8 may be stamped to obtain a plurality of individual syndet bars.

The present invention i8 illustrated further by the following examples.

Era~ple 1 39.13 parts by weight sodium cocoyl isethionate and 32.02 parts stearic acid were melted together at 180-F, and the resulting mixture wa8 then chilled and flaked. Thereafter, 10.0 parts sodium bicarbonate, 6.71 parts sodium tallow soap, 1.18 parts sodium coco 80ap, 3-95 parts sodium alpha olefin sulfonate, 1.58 parts perfume, and 5.43 parts water were added to the isethionate-stearic acid mixture and blended to homogeneity using an amalgamator- This mixture was then refined and extruded, and individual bar8 cut from the billet.

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Bxample 2 The syndet bar compositions in Table II were obtained by admixing sodium bicarbonate and fragrance with base compositions having a nominal analysi8 as shown in Table I. Sodium bicarbonate, fragrance and varioua base compositions having different moisture levelg (a difficult parameter to control) were blended together to obtain composite Compositions 2A
through 2E shown in Table II- The actual bicarbonate and water levels are indicated in the Table II.

TABLE I
Base Composition Constituent Concentration, Wt. %

Jordapon CI (1) 46.0 Stearic Acid 30.9 Bio Terge AS90 (2) 4.7 Toilet Soap (3) 9.4 Sodium Isethionat 1.63 Sodium Chloride 0.44 Preservative 0.03 Water 6.93 Total 100.0 79~1.
f~

(1) Sodlum cocoyl i8ethionate sold by PPG/Mazur Chemical Co.
(80% Active).

(2) Sodium alpha olefin 8ulfonate 801d by Stepan Co. (90 Active).

(3) 15/85 coco/tallow soap.

TABI~ II

Syndet Bar Com~ositions Constituent Concentration, Wt. %

Base Composition 98.393.3 88.3 83.3 78.3 Sodium Bicarbonate 0 5.0 10.0 15.0 20.0 Fragrance 1.71.7 1.7 1.7 1.7 Total 100.0100.0100.0 100.0 100.0 ~aHC03 Analysis (wt. %) 05.56 10.25 15.56 21.13 ~oisture Analysis (wt. %) 5.7 5.7 5.3 6.5 6.1 ~ 2(~9~

A homogeneous mixture of the constituents of Compositions 2A through 2E wa8 obtained in an amalagamator. The homogeneous mixture was passed through a refiner and an extruder to obtain 20 gram billets of essentially constant moisture (6.1+0.4%), which were evaluated as outlined below.

Commercially available dish cleaning articles of the type shown in Fig. 2 and sold under the trade name LEM-METM were cut open and the soap bar8 contained therein removed. Ten (10) syndet bars of each Composition 2A through 2E were placed inside the now empty pocket8 of the LEM-ME scrubbers, and the scrubbers were resealed. Referring to Fig- 2, the laminate9 112 and 118 are of a closed cell polyurethane ester having a density of 1.7 lbs/ft3 and a porosity of about 50-60 pores/in2. The laminate 112 thickness i8 about 0-5 inch, while the laminate 118 thickness is about 0.1 inch. Laminate 114 is comprised of an open cell polyurethane ester and has a variable thickness ranging between 0.25 and 0.75 inch. Its density is about 2.3 lbs/ft3 and has a porosity of from 10-50 pores/in2.

These articleg were tested over a five week period as follow~. An article was secured in an apparatus eguipped with a roller which was adapted to uniformly s~ueeze each of the 2~t:)7~

articles. The roller then made 2S stroke8 ln 2 1/2 minutes and operated in this manner while 40-C water was sprayed onto the article. Thereafter, the article was inverted and another cycle of 25 strokes for 2 1/2 minuteg was conducted. This procedure ~as repeated for each article, and was repeated for five days.
After the fifth run, the articles were permitted to dry thoroughly in air for about 48 hours, except that two of the ten articles were oven-dried to constant weight and the weight of syndet delivered was determined. The remaining articles were sub~ected to the same procedure outlined above. The test was carried out for a total of five weeks (after which all ten articles for each Compositions 2A through 2E had been oven-dried and the amount of syndet delivered measured). The results are repeated in Table III below.

TABLE III

Average Weight of Syndet Composition Delivered From Bar (grams) $NaHC03 Week 1 Week 2 Week 3 Week 4 Week 5 2A 0 8.4 17.8 19.7 19.1 19.7 2B 5 15.7 20.5 19.8 19.8 20.1 2C 10 9.4 14.8 19.0 19.4 19.9 2D 15 6.3 10.3 14.0 16.1 19.3 2E 20 6.9 10.5 13.8 15.6 19.1 2(~3~79~ ~

It is seen that the bicarbonate level had a direct influence on length of life of the 8yndet bar. Thu8, after two weeks the control of Compo8ition 2A having 0~ bicarbonate and the bar of Compo8ition 2B having 5% bicarbonate had been substantially used up, while the remaining bars had significantly greater (with a 95% confidence limit) mass indicating a slower rate of dissolution.

ExamPle 3 Similar tests were conducted to ascertain the importance of ~oisture level on length of life- The Compositions 3A through 3J were prepared by ad~usting the moisture level in a base composition similar to the Ba8e Compo8ition of Table I and then adding sodium bicarbonate and fragrance to the desired level.
These composition~ were tested a8 previou81y indicated except the test was terminated after three day8 in the second week.
The residual weight of the syndet bar wa8 then determined. The results are indicted below in Table IV. In Table IV the initial bicarbonate and water moi8ture level8 of the bar were analytically determined. The 8yndet bar had an initial weight of 20 grams.

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TABLE rv Weight of Bar Wt. % (Actual) (gm8) Remalning Composition H20 NaHC03A~ter E~ght Days 3A 3.54 0 5.22 3B 3.65 0 S,30 3C 3.589.05 4.70 3D 3.5120.01 12.39 3E 4.499.04 7.18 3F 4.709.11 7.30 3G 4.0019.32 13.23 3H 5.4119.98 14.23 3I 6.18 0 7,40 3J 6.268.98 8.86 AnalysiS on thi8 data indicates that the increases in the length of life of the 8yndet bar8 of the present invention is linear with regard to water content and parabolic with respect to bicarbonate level.

Example 4 Base Composition of Table I was used to make bars of the following compositions:

(~? Z(~79~1 TABLE V

Constituent Concentration, Wt. %
(6) Base Composition 82.3 80.3 78.3 82.3 78.3 73.3 Sodium Bicarbonate 15.0 15.0 15.0 15.0 15.0 15.0 Fragrance 1.7 1.7 1.7 1.7 1.7 1.7 Stepanol WA100(4) 1.0 3.0 5.0 Nacconal 90G (5) - _ _ 1.0 5.0 10.0 (4) Sodium lauryl sUlfate sold by Stepan Chemical Co. (99% Active).

(5) Sodium alkylaryl sulfonate ~old by Stepan Chemical Co. (90%
Active).

(6) Extruded bars were not acceptable.

Claims (20)

1. A synthetic detergent bar comprising by weight of the bar from about 20 to about 90% of a lime soap dispersant and an amount of sodium bicarbonate effective to slow the rate of dissolution of the bar in water, said bar having a moisture level of from about 3.5 to about 8% by weight of the bar.

2. The synthetic detergent bar of Claim 1 wherein the lime soap dispersant is in the range of from about 30 to about 50%.

3. The synthetic detergent bar of Claim 1 wherein the sodium bicarbonate is present in an amount of from about 10 to about 30%.

4. The synthetic detergent bar of Claim 2 wherein the sodium bicarbonate is present in an amount of from about 10 to about 20%.

5. The synthetic detergent bar of Claim 1 wherein the moisture level is from about 5 to about 7%.

6. A synthetic detergent bar comprising by weight of the bar from about 20 to about 90% of a lime soap dispersant selected from the group consisting of the neutralized fatty acid esters ofisethionic acid and the neutralized fatty acid half esters of succinic acid, and from about 10 to about 30% sodium bicarbonate, the moisture level being from about 3.5 to about 8% by weight.

7. The synthetic detergent bar of claim 6 wherein the lime soap dispersant is sodium cocyl isethionate.

8. The synthetic detergent bar of Claim 6 wherein the lime soap dispersant is present in an amount of from about 30 to about 50%.

9. The synthetic detergent bar of Claim 6 further comprising up to about 50% of a non-soap synthetic detergent that is not a lime soap dispersant.

10. The synthetic detergent bar of Claim 8 further comprising up to about 25% soap.

11. The synthetic detergent bar of Claim 10 wherein the soap is present in an amount of from about 5 to about 15% and is a mixture of about 10 to 25% coconut soap and of about 75 to about 90% tallow soap, by weight of the soap mixture.

12. The synthetic detergent bar of Claim 9 wherein the non-soap synthetic detergent is sodium alpha olefin sulfonate

13. The synthetic detergent bar of Claim 6 further comprising a waxy, essentially water-insoluble binder in an amount of up to 50% by weight.

14. The synthetic detergent bar of Claim 13 wherein the binder is selected from the group of fatty acids, glycol esters of fatty acids, and amides of fatty acids, and is present in an amount of from about 10 to about 40%.

15. The synthetic detergent bar of Claim 6 further comprising one of more of the following in an amount suitable to provide its functionally intended purpose: fragrance, dye, emollient, chelating/sequestering agent, stabilizer, preservative and antimicrobial.

16. A scrubbing article comprising a porous substrate including means for interiorly retaining a synthetic detergent bar, and a synthetic detergent bar retained within the substrate, said synthetic detergent bar comprising a synthetic detergent and an amount of sodium bicarbonate effective to slow the rate of dissolution of the bar in water, said bar having a moisture level of between about 3.5 to about 8% by weight of the bar.

17. The scrubbing article of Claim 16 wherein the porous substrate comprises a first laminate and a second laminate, said laminates affixed as to form an interior pocket as said means for containing the synthetic detergent bar.

18. The scrubbing article of Claim 17 further comprising a third laminate disposed between said first and second laminates, the synthetic detergent bar being between the first and third laminates.

19. The scrubbing article of Claim 18 wherein the first laminate is of an open celled polymeric material and the second laminate is of a closed cell polymeric material.

20. The scrubbing article of Claim 19 wherein the third laminate is made of the same polymeric material as the second laminate.