CA1333245C

CA1333245C - Laundry detergent bar containing linear alkyl benzene sulfonate

Info

Publication number: CA1333245C
Application number: CA000538834A
Authority: CA
Inventors: Benny Sin-Hoi Yam
Original assignee: Procter and Gamble Co
Current assignee: Procter and Gamble Co
Priority date: 1987-06-04
Filing date: 1987-06-04
Publication date: 1994-11-29
Anticipated expiration: 2011-11-29
Also published as: GB8812967D0; MY103568A; MX169803B; GB2205580A

Abstract

Laundry detergent bars are formulated with linear alkyl benzene sulfonate and detergent builders. The process comprises the steps of: (a) supplying substan-tially anhydrous linear alkyl benzene sulfonic acid, the linear alkyl chain of which contains from about 8 to about 20 carbon atoms; (b) neutralizing the afore-mentioned sulfonic acid with a subtantially anhydrous granular base selected from the group consisting of alkali metal carbonates, alkali metal bicarbonates, and mixtures thereof to form alkali metal linear alkyl benzene sulfonate; (c) blending detergent builder with the aforementioned sulfonate; and (d) preparing laundry detergent bars from the thus formed mixture of detergent builder and alkali metal linear alkyl benzene sulfonate.
Importantly, any water which is blended with the alkali metal linear alkyl benzene sulfonate subsequent to the neutralization step mentioned above must be in the form of water of hydration of a material such as an inorganic builder salt used in the formulation. The resulting bars comprise from about 5% to about 50% alkali metal linear alkyl benzene sulfonate and from about 10% to about 85%
detergent builder.

Description

~.3332~

LAUNDRY DETERGENT BAR CONTAINING
LINEAR ALKYL BENZENE SULFONATE

BENNY SIN-HOI YAM

BACKGROUND OF THE INVENTION

This invention relates to laundry detergent bars and to processes for manufacturing them. More particularly, it is concerned with hard, long wearing, low smearing, built laundry detergent bars based on linear alkyl benzene sulfonates and with novel processes for manufacturing them.

Detergent compositions in the form of synthetic detergent granules and liquids are used in many societies in the laundering of clothing, particularly in those societies where mechanical washing machines are common. In portions of such societies, and even more frequently in societies where mechanical washing machines are not common, laundry detergent bars comprising synthetic organic surfactants and detergency builders are used in the laundering of clothing.

For many years workers in the field have attempted to formulate laundry detergent bars which are effective in cleaning clothing; which have acceptable sudsing characteristics in warm and cool water and in hard and soft water; which have acceptable wear rates, hardnesses, and feel; which have low smear, and which have pleasing appearances. Examples of such exemplary laundry detergent bars are described in, for example, ,/~ ~

2 13332~
U. S. Patent 3,178,370 (issued to Okenfi~ss or~ April 13, 196~ and incorporated herein by reference) which describes laundry detergent bars comprising sodium alkyl benzene sulfonate, sodium tripolyphosphatc, sodium bicarbonate, trisodium orthophospl1ate, and water, and processes for manufacturing these. Philippine Patent 13,778 (issued to Anderson on September 23, 1980) describes synthetic detergent laundry bars containing surfactant, alkali metal pyrophosphate, from about 18% to about 6096 alkaline earth metal carbonate, and from about 1 % to about 20% water .

U.S. Patent 3,708,425 (issued January 2, 1973 to Corupa et al., ) describes detergent bars containing alkyl benzene sulfonate, from about 5% to about 60% puffed water-soluble hydratable salt (i.e., puffed borax), and detergency builders in which, it is speculated, some of the water in the system is taken up as water of hydration of a hydratable salt thereby contributing to the hardness of the bar.

Despite advances in laundry detergent bar technology, such as described in the above three patents, the search for improved laundry detergent bars has continued. Three technical problems have been particularly resistant to solution. These are the related problems of insufficient bar hardness, excessive wear rate, and high smear which result when linear alkyl benzene sulfonates are used in detergent bars in place of the previously ubiquitous branched chain alkyl benzene sulfonates. The present invention efficiently and unexpectedly solves these three problems .

SUMMARY OF THE I NVENTION

The present invention is of a process for making laundry detergent bars formulated with linear alkyl benzene sulfonate and detergent builders. The process comprises the steps of:

13~32~5 (a) supplying substantially anhydrous linea~ alkyt ~nzene sulfonic acid, the linear alkyl chain of which contains from about 8 to about 20 carbon atoms;

(b) neutralizing the aforementioned sulfonic acid with a substantially anhydrous granular base selected from the group consisting of alkali metal carbonates, alkali metal bicarbonates, and mixtures thereof to form alkali metal linear alkyl benzene sulfonate;

(c) blending detergent builder with the aforementioned sulfonate; and (d ) preparing laundry detergent bars from the thus formed mixture of detergent builder and alkali metal linear alkyl benzene sulfonate.

Importantly, any water which is blended with the alkali metal linear alkyl benzene sulfonate subsequent to the neutralization step mentioned above must be in the form of water of hydration of a material such as an inorganic builder salt used in the formulation. The resulting bars comprise from about 5% to about 50% alkali metal linear alkyl benzene sulfonate and from about 1096 to about 85% detergent builder.

In an alternate embodiment of the process of this invention, substantially anhydrous alkali metal linear alkyl benzene sulfonate is supplied and blended with detergent builder and laundry detergent bars are formed as previously described.

The present invention also includes the hard, long wearing, low smearing laundry detergent bars produced by the aforementioned processes.

4 13~3245 DETAILED DESCRIPTION OF THE INVENTION

Whi le this specification concludes with claims distinctly pointing out and particularly claiming that which is regarded as the invention, it is believed that the invention can be better understood through a careful reading of the following detailed description of the invention. In this specification all percentages are percentages by weight, all temperatures are expressed in degrees Celsius, and the decimal is represented by the point (. ) .

The first step in the process of this invention is the supplying of substantially anhydrous linear alkyl benzene sulfonic acid to a reaction vessel. The second step is the neutralization of the acid in the reaction vessel to form a sulfonate surfactant.

For a number of years laundry detergent bars, and laundry detergent compositions generally, were based on alkali metal salts of branched chain alkyl benzene sulfonic acid, which are generally referred to as alkali metal branched chain alkyl sulfonates, in which will hereinafter be generically referred to as ABS. Based on a variety of considerations, including aspects of biodegradability, the use of ABS has in recent years been curtailed, the ABS being replaced by alkali metal salts of linear alkyl benzene sulfonic acid, which are commonly called alkali metal linear alkyl benzene sulfonates, and which will hereinafter be generically referred to as LAS. The distinction between ABS and ~AS is readily apparent from the difference in their names. The alkyl chain attached to the benzene radical in ABS is branched.
That is to say, the backbone of the alkyl chain includes pendent methyl, ethyl, etc. groups. In LAS, the alkyl chain attached to the benzene radical is primarily linear.

In the preferred aspect of the present invention, LAS is prepared during the second step of the process of this invention by the dry neutralization of the substantially anhydrous linear 13~32 ~

alkyl benzene sulfonic acid suppliea in th~ firs; ~tep of the process of this invention. The linear alkyl benzene sulfonic acid can be obtained by any of various processes well known to those skilled in the art, such as the process of sulfonating alkyl benzene through the use of sulfur trioxide. ) The alkyl chain of the linear alkyl benzene sulfonate comprises from about 8 to about 20 carbon atoms. Preferably, the alkyl chain comprises from about 10 to about 15 carbon atoms. Mixtures of sulfonic acids having a distribution of alkyl chain lengths is acceptable within the context of the present invention.

Dry neutralization comprises mixing the linear alkyl benzene sulfonic acid with a granular base under such conditions that the amount of fluid present is insufficient to destroy the particulate nature of the granular base. Dry neutralization is described in detail in the aforementioned patent to Okenfuss. The dry neutralization is preferably conducted at a temperature greater than about 40. Preferably, at least about 90% of the substantially anhydrous granular base will pass through a 100 mesh screen. The aforementioned reaction vessel can be any suitable equipment well known to those skilled in the art of manufacturing LAS.

The granular base used to neutralize the linear alkyl benzene sulfonic acid is substantially anhydrous and is selected from the group consisting of alkali metal carbonates, alkali metal bicarbonates, and mixtures thereof. Preferably, the alkali metal is sodium. Preferably, the base is sodium carbonate. The amount of substantially anhydrous granular base used in the neutralization step is at least the stoichiometric amount required to neutralize the sulfonic acid, preferably from about 2 to about 10 times the stoichiometric amount.

As will be discussed in more detail hereinafter, it is important in the manufacture of laundry detergent bars that the quantity of free water or water associated with the LAS be maintained at a minimum. With this requirement in mind, the linear alkyl benzene sulfonic acid and the granular base must be 13332~L~

substantially anhydrous. Tile linear alkyl b~ e sulfonic acicl and the granular base used to neutralize it are substantially anhydrous within the context of this invention when the total water present in the sulfonic acid and in the base (including free water and water of hydration) is less than that quantity of water which, when added to the quantity of water formed during the neutralization reaction, will result in the thus-formed alkali metal linear alkyl benzene sulfonate having a moisture content of not more than about 4%. To phrase the same requirement in different words, the linear alkyl benzene sulfonic acid and the granular base used to neutralize it are substantially anhydrous within the context of this invention when the resulting alkali metal linear alkyl benzene sulfonate has a moisture content of not more than about 4%, the moisture in the sulfonate having been derived from any free water present in the acid and in the base, any water of hydration present in the acid and in the base, and the water formed during the neutralization reaction. The LAS is considered to be substantially anhydrous when it contains less than about 4%
moi stu re .

The third step in the process of this invention is the incorporation of detergent builder into the LAS formed in the second step of the process of this invention. The detergent builder not only functions as a detergency builder during use of the laundry detergent bar (as by, for example, sequestering hardness and aiding in control of the pH of the wash solution), but it also provides enhanced physical properties to the bar.

These detergent builders can be, for example, water-soluble salts of phosphates, pyrophosphates, orthophosphates, and higher polyphosphates. Specific preferred examples of inorganic phosphate builders include sodium and potassium tripolyphosphates and pyrophosphates.

Nonphosphorus-containing materials can also be selected for use herein as detergency builders. Specific examples of nonphosphorus, inorganic detergency builders include 7 13332~5 water-soluble inorganic carbonate and bicarbonate salts. The alkali metal (e.g., sodium and potassium) carbonates, bicarbonates, and silicates are particularly useful herein.

Aluminosilicate ion exchange materials useful as detergency builders in the practice of the instant invention are commercially available. These aluminosilicates can be crystalline or amorphous in structure and can be either naturally occuring or synthetically derived. A method for producing aluminosilicate ion exchange materials is discussed in the U. S. Patent Number 3,985,669, issued to Krummel et al . on October 12, 1976.
Preferred synthetic crystalline aluminosilicate ion exchange materials useful herein are available under the designations Zeolite A, Zeolite B, and Zeolite X. In an especially preferred embodiment, the crystalline aluminosilicate ion exchange material in Zeolite A and has the formula:

Na12~Alo2)l2- (si2)12] XH2G

wherein x is from about 20 to about 30, especially about 27.

Water-soluble organic detergency builders are also useful herein. For example, alkali metal, ammonium and substituted ammonium polycarboxylates are useful in the present compositions.
Specific examples of useful polycarboxylate builder salts include sodium, potassium, ammonium and substituted ammonium salts of ethylenediaminetetraacetic acid, nitrilotriacetic acid, oxydisuccinic acid, mellitic acid, benzene polycarboxylic acid, polyacrylic acid, polymaleic acid, and citric acid.

Other useful polycarboxylate detergency builders are the materials set forth in U. S. Patent 3,308,067 issued to Diehl on March 7, 1967. Examples of such materials include the water-soluble salts of homo- and co-polymers of aliphatic carboxylic acids such as acrylic acid, maleic acid, itaconic acid, mesaconic acid, fumaric acid, aconitic acid, citraconic acid, and methylenemalonic acid.

r~

133324~

Suitable non-polymeric polycarboxylates are the polyacetal carboxylates described in U. S. Patent Number 4,144,226 issued March 13, 1979 to Crutchfield et al and U. S. Patent Number 4,246,495 issued March 27, 1979 to Crutchfield et al .
These polyacetyl carboxylates can be prepared by bringing together under polymerization conditions an ester of glyoxylic acid and a polymerization initiator. The resulting polyacetal carboxylate ester is then attached to chemically stable end groups to stabilize the polyacetal carboxylate against rapid depolymerization in alkaline solution, converted to the corresponding salt, and added to a surfactant.

Mixtures of detergent builders can be used in the present invention .

Preferably, tlle detergent builder, or at least one of the detergency builders, is a hydratable salt. Most preferably, the detergency builder is sodium tripolyphosphate.

The detergent builder can be blended into the LAS by any of the techniques commonly used in the manufacture of detergent bars. Other components useful in laundry detergent bars, as mentioned hereinafter, can be added to the composition at this point in the manufacturing process.

It is critical that the addition of free water to the system be avoided in the third and succeeding steps of the process of this invention. Any water added to the system must be in the form of water of hydration of the inorganic salts incorporated into the substantially anhydrous LAS found in the aforementioned second step. For example, aqueous solutions or suspensions of the optional components mentioned hereinafter must first be mixed with a hydratable inorganic salt, such as sodium tripolyphosphate, prior to incorporation into the LAS. This procedure will allow the aqueous phase of solution or suspension ~A

9 1~3?J~
to become bound to the inorganic s31t~ as ~later of hydration.
Any moisture required for processing reasons must also be first incorporated into the inorganic salts as water of hydration.

While the requirement of avoiding the addition of free water to the substantial Iy anhydrous LAS during the manufacture of the bar is couched in absolute terms, it must be recognized that as a practical matter it is virtually impossible to avoid the absolute elimination of all free moisture during any commercial process.
The addition of free water to the substantially anhydrous LAS is avoided, within the contemplation of the present invention, so long as the free water incorporated into the system represents less than about O . 5% of the total bar .

Without expressing an intention to be bound by any theory of operation, it can be stated that it is believed that the unexpected, salutory properties of the laundry detergent bars manufactured by the process of the present invention result from the absence of water associated with the LAS of the bar. The undesirable softness of bars made with LAS occurs when the moisture in the bar is distributed between the LAS and the inorganic salts in the bar in an unfavorable ratio. It appears that the higher this ratio of water associated with LAS to water associated with inorganic salts, the softer the bar. Any moisture in the bar will, with time, tend to distribute itself among the various components. The relatively greater hygroscopic nature of the inorganic salts as compared to that of the LAS tends to naturally cause a greater portion of the moisture to be associated as water of hydration with the inorganic salt than with the LAS.
This hygroscopic nature of the inorganic salts is sufficiently strong to prevent significant quantities of water of hydration of the salt from migrating to the LAS molecules and becoming associated with them. However, this hygroscopic property is not sufficiently strong to disassociate a sufficient quantity of moisture from the LAS so as to prevent the partially hydrated LAS from making the bar soft. Ensuring that any moisture in the bar is 13332~

present primarily as water of hydration of the inorganic salts ensures that the level of moisture associated with the LAS is sufficiently small so as to not result in a soft bar.

Any of the various and sundry materials commonly used in the laundry detergent compositions generally and laundry detergent bars specifical Iy can be incorporated into the laundry detergent bar of the present invention. Preferably, these materials are incorporated into the bar either concurrently with or subsequently to the incorporation of the alkali metal tripolyphosphate therein.

In addition to the LAS, the detergent bars of the present invention can contain up to about 30% by weight of other, optional auxiliary surfactants as commonly used in detergent products.
(Surfactants are sometimes referred to in the art as "detergents"
or "detergent compounds.") A typical listing of the classes and species of surfactants useful herein appears in U. S. Patent Number 3,664,961, (issued to Norris on May 23, 1972).
The following list of surfactants and mixtures thereof which can be used in the instant detergent compositions is representative of such materials, but is not intended to be limiting.

Water-soluble salts of the higher fatty acids (i.e. "soaps") are useful as auxiliary surfactants in the instant composition.
This class of surfactants includes ordinary soaps such as the sodium, potassium, ammonium and alkanolammonium salts of higher fatty acids containing from about 8 to about 24 carbon atoms and preferably from about 10 to about 20 carbon atoms. Soaps can be made by direct saponification of fats and oils or by the neutralization of free fatty acids. Particularly useful are the sodium and potassium salts of the mixtures of fatty acids derived from coconut oil and tallow, i.e., sodium or potassium tallow and coconut soap.

Another class of surfactants useful herein includes water-soluble salts, particularly the alkali metal, ammonium and 1333~3 alkanolammonium salts, of organic sul furic reat;tion products having in their molecular structure an alkyl group containing from about 8 to about 22 carbon atoms and a sulfuric acid or sulfuric acid ester group. Examples of this group of synthetic surfactants are the sodium and potassium alkyl sulfates, especially those obtained by sulfating the higher alcohols (C8-C1 8 carbon atoms) produced by reducing the glycerides of tallow or coconut oil .

Other anionic surfactants useful herein include sodium alkyl glyceryl ether sulfates, especially those ethers of higher alcohols derived from tallow and coconut oil; sodium coconut oil fatty acid monoglyceride sulfonates and sulfates; and sodium or potassium salts of alkyl phenol ethylene oxide ether sulfates containing from about 1 to about 10 units of ethylene oxide per molecule and wherein the alkyl groups contain about 8 to about 13 carbon atoms .

Yl~ater-soluble nonionic synthetic surfactants are also useful as auxiliary surfactants in the instant laundry detergent bar.
Such nonionic surfactants can be broadly defined as compounds produced by the condensation of ethylene oxide groups (hydrophilic in nature) with an organic hydrophobic compound, which may be aliphatic or alkyl aromatic in nature. The length of the polyoxyethylene group which is condensed with any particular hydrophobic group can be readily adjusted to yield a water-soluble compound having the desired degree of balance between hydrophilic and hydrophobic elements.

For example, a wel l-known class of nonionic synthetic surfactants is made available on the market under the trademark " Pluronic" . These compounds are formed by condensing ethylene oxide with a hydrophobic base formed by the condensation of propylene oxide with propylene glycol. Other suitable nonionic synthetic surfactants include the polyethylene oxide condensates of alkyl phenols, e.g., the condensation products of alkyl phenols 13332~

having an alkyl group containing from ab~u~ ~ ta c~bout 13 carbon atoms in either a straight chain or branched chain configuration, with ethylene oxide, the ethylene oxide being present in amounts equal to from about 4 to about 15 moles of ethylene oxide per mole of alkyl phenol.

The water-soluble condensation products of aliphatic alcohols having from about 8 to about 22 carbon atoms, in either straight chain or branched configuration, with ethylene oxide, e.g., a coconut alcohol-ethylene oxide condensate having from about 5 to about 30 moles of ethylene oxide per mole of coconut aJcohol, the coconut alcohol fraction having from about 10 to about 14 carbon atoms, are also nonionic surfactants useful herein.

Semi-polar nonionic surfactants useful herein include water-soluble amine oxides containing one alkyl moiety of from about 10 to 20 carbon atoms and 2 moieties selected from the group consisting of alkyl groups and hydroxyalkyl groups containing from 1 to about 3 carbon atoms; water-soluble phosphine oxide surfactants containing one alkyl moiety of from about 10 to 20 carbon atoms and 2 moieties selected from the group consisting of alkyl groups and hydroxyalkyl groups containing from 1 to about 3 carbon atoms; and water-soluble sulfoxide surfactants containing one alkyl or hydroxyalkyl moiety of from about 10 to about 20 carbon atoms and a moiety selected from the group consisting of alkyl and hydroxyalkyl moieties of from 1 to about 3 carbon atoms.

Ampholytic surfactants useful herein include aliphatic derivatives of heterocyclic secondary and tertiary amines in which the aliphatic moiety can be straight chain or branched and wherein one of the aliphatic substituents contains from about 8 to about 18 carbon atoms and at least one aliphatic substituent contains an anionic water-solubilizing group.

Zwitterionic surfactants useful herein include derivatives of aliphatic quatemlary ammonium, phosphonium and sulfonium compounds in which the aliphatic moietics can be st~aight ~hain or branched, and wherein one of the aliphatic substituents contains from about 8 to about 18 carbon atoms and one contains an anionic water-solubilizing group.

Other surfactants useful herein include the water-soluble salts of esters of alpha-sulfonated fatty acids containing from about 6 to about 20 carbon atoms in the fatty acid group and from 1 to about 10 carbon atoms in the ester group; water-soluble salts of 2-acyloxy-alkane-1-sulfonic acids containing from about 2 to about 9 carbon atoms in the acyl group and from about 9 to about 20 carbon atoms in the alkane moiety; alkyl ether sulfates containing from about 10 to about 20 carbon atoms in the alkyl group and from about 1 to about 12 moles of ethylene oxide;
water-soluble salts of olefin sulfonates containing from about 12 to 20 carbon atoms; and beta-alkyloxy alkane sulfonates containing from about 1 to 3 carbon atoms in the alkyl group and from about 8 to 20 carbon atoms in the alkane moiety.

It is to be recognized that any of the foregoing auxiliary surfactants can be used separately herein, or in mixtures of surfactants. They are used at levels of from about 3 to about 30~.

In addition to the auxiliary surfactants mentioned above, it has been found to be advantageous, (in terms of bar hardness, etc., ) to have a hydrotrope, or mixture of hydrotropes, present in the laundry detergent bar. Preferred hydrotropes include the alkali metal, preferably sodium, salts of tolune sulfonate, xylene sulfonate, cumene sulfonate, sulfosuccinate, and mixtures thereof.
Preferably, the hydrotrope, in either the acid form or the salt form, and being substantially anhydrous, is added to the linear alkyl benzene sulfonic acid prior to its neutralization. The hydrotrope is preferably present at from about 1% to about 5% of the laundry detergent bar.

14 13332~'~

Another useful optional component of the laundry detergent bars of this invention is silicate. The usual amounts and ratios of silicate are satisfactory, and are typically up to about 15%
silicate solids having a wt. ratio of SiO2 to Na2O between about 1.6:1 and about 3.4:1.

The compositions of this invention can also contain colloidal silica. An example of this material is Ludox (T.M. ) made by E. I. du Pont de Nemours, Inc.

Borates and perborates can also be used in the detergent laundry bars of this invention as can bleach activators. Enzymes can also be used in the bars.

Sodium sulfate is a well-known filler that is compatible with the compositions of this invention. It can be a by-product of the surfactant sulfation process or it can be added separately.

Minor ingredients as wel I known in the detergent arts can also be used in the bars of the present invention. Soil suspending agents such as water-soluble salts of carboxymethylcellulose and carboxyhydroxymethylcellulose; and polyethylene glycols having a molecular weight of about 400 to 10,000 can be used in the present invention. Dyes, pigments, optical brighteners, germicides, and perfumes can also be added in varying amounts as desired.

Suds control agents are common additives to detergent compositions and can be used in the bars of this invention.
These may be suds boosters, such as amine oxides, e.g. coconut dimethylamine oxide; and amides, e.g. dimethyl amide and diethanol amides having 10 to 14 carbon atoms in the alkyl chains.
Alternatively, if desired, they may be suds suppressors such as the higher fatty acids taught in U. S. Patent 2,954,347 issued on September 27, 1960 to St. John et al; high melting microcrystalline waxes as taught in U. S. Patent Number 4,056,481 issued November 1, 1977 to Tate et al, and silicone/silica mixtures as taught in British Patent 1,304,803 issued on May 30, 1973 to Bartalotta et al .

The fourth step in the process of the present invention is preparing detergent bars from the substantially anhydrous mixture of LAS and detergent builder (and optional components).
Bars are formed by any of the techniques common to the industry. The mixing of the components is preferably accompl ished by a ribbon blender or an amagamator and the components are then mechanical Iy worked and formed into a homogeneous composition as, for example, by milling. The homogeneous mixtu re is then extruded at a temperatu re of from about 35 to about 80 after which it is cut or stamped into individual bars which are then preferably individually wrapped with the appropriate packaging material.

As noted, the laundry detergent bars of this invention exhibit exemplary hardness. Bar hardness is usually measured with the aid of a pentrometer. For example, a penetrometer made by Precision Scientific Inc., model number 73510 can be used.
When a Precision cone number 73539 is forced into the surface of the bar under a loading of 150 grams, the depth of penetration of the cone, measured in millimeters (mm), is an indication of bar hardness . A bar yielding a penetration of less than about 1.5 mm under the conditions indicated can be considered to be a firm bar, suitable for practical use. Softener bars (i.e., bars exhibiting a greater penetration) can still be used, but the usefullness of the bars and the acceptance of the. bars by consumers decrease as the softness of the bars increases.

"Smear" is a term used in the art to denote the gelatinous mass formed on the underside of a laundry detergent bar when the bar is allowed to stand in a small quantity of water, as after use when the bar is placed in a soap dish. Bars made in .~

13~324S

accordance with the present invention exhibit a smaller quantity of smear than do similar bars not made by the process of this invention .

By way of exemplification, and not by way of limitation, the following examples are presented.

17 13332~5 Example I

5.14 kilograms (kg) linear alkyl benzene sulfonic acid having an average of 12 carbon atoms in the alkyl chain and having a free moisture content 0.15% is supplied to a reaction vessal with agitation, containing 4. 71 kg anhydrous sodium carbonate. The neutralization is carried out at about 60. Following the neutralization of the acid, 6.27 kg sodium tripolyphosphate having a total moisture content of about 3.5% (in the hydrate form) is added to the just-formed sodium linear alkyl benzene sulfonate in a blender. In addition, 6.56 kg sodium sulfate, 1 . 36 kg sodium carboxyl methyl cellulose, 0.23 kg brighteners, 0.65 kg dyes, and 0 . 68 kg perfumes are added to the system in the blender.
Care is exercised to insure that essentially no free water is incorporated into the system; the aqueous suspensions of minor ingredients are first mixed with the sodium tripolyphosphate before they are incorporated into the system. Following the thorough mixing of the components in the blender, the composition is milled, plodded and cut into bars in the conventional way. The resulting bar having the composition below is sufficiently hard to be useful in the laundrying of clothing. (All ingredients are listed on an anhydrous basis and as a percentage of the final bar. ) Component %

Sodium dodecyl LAS 23. 5 Sodium tripolyphosphate 24 . 0 Sodium carbonate 18 . 0 Sodium carboxy methyl cellulose 0.6 Brighteners 0. 1 Water 4- 3 Dyes 0. 21 Perfume 3 Sodium Sulfate Balance 13332~

Example I I

A laundry detergent bar having the following finished composition is prepared by the technique shown in Example 1.

Component 96 Sodium dodecyl LAS 30 . 0 Sodium toluene sulfonate 3 . 0 Sodium tripolyphosphate 24. 0 Sodium carbonate 18.0 Sodium carboxy methyl cellulose 0.6 Brighteners 0.1 Water 4 5 Dyes 0 . 21 Perfume 0 . 3 Sodium Sulfate Balance Sodium toluene sulfonate is predispersed in the linear alkyl benzene sulfonic acid. The mixture is then added to a reaction vessel containing sodium carbonate. The bar is prepared using the same procedure as described in Example 1. The bar exhibits exemplary hardness.

13~32~S
,9 Example l l I

A laundry detergent bar having the following finished composition is prepared as in Example l l .

Component %

Sodium dodecyl LAS 23 . 5 Sodium toluene sulfonate 3.0 Sodium tripolyphosphate 24. 0 Sodium carbonate 18.0 Sodium polyacrylate 3 . 0 Sodium carboxy methyl cellulose 0.6 Brighteners 1 Water 4 3 Dyes 0 . 21 Perfume o . 3 Sodium Sulfate Balance The sodium polyacrylate, in the form of a 55% aqueous dispersion, is sprayed onto anhydrous sodium tripolyphosphate prior to its being blended with the LAS. The bar exhibits exemplary hardness .

1~3324~

Example IV

A laundry detergent bar having the following finished composition is prepared as in Example l l.

Component %

Sodium dodecyl LAS 30 . 0 Sodium toluene sulfonate 3 . 0 Sodium pyrophosphate 10 . 0 Sodium carbonate 18 . 0 Sodium carboxy methyl cellulose 0.6 Brighteners 0.1 Water 4 5 Dyes 0. 21 Perfume 0 . 3 Sodium Sulfate Balance The bar exhibits exemplary hardness.

What is Claimed is:

Claims

1. A process of making a laundry detergent bar, which process comprises the steps of:

(a) Supplying substantially anhydrous linear alkylbenzene sulfonic acid, the linear alkyl chain of which contains from about 8 to about 16 carbon atoms, to a reaction vessel;

(b) Neutralizing said sulfonic acid in said reaction vessel with a substantially anhydrous granular base selected from the group consisting of alkali metal carbonates, alkali metal bicarbonates, and mixtures thereof to form alkali metal linear alkylbenzene sulfonate;

(c) Blending detergent builder with said sulfonate; and (d) Preparing said detergent bar from the thus-formed mixture of detergent builder and sulfonate;

wherein said bar comprises from about 5% to about 50% by weight alkali metal linear alkylbenzene sulfonate and from about 5% to about 85% said detergent builder; and wherein any water blended with said alkali metal alkylbenzene sulfonate subsequent to said neutralizing step is in the form of water of hydration of an inorganic salt.

2. The process of Claim 1 wherein said sulfonic acid comprises from about 3% to about 15% by weight (of said sulfonic acid) of a hydrotrope selected from the group consisting of alkali metal toluene sulfonate, alkali metal xylene sulfonate, alkali metal cumene sulfonate, alkali metal sulfosuccinate, toluene sulfonic acid, xylene sulfonic acid, cumene sulfonic acid, sulfosuccinic acid, and mixtures thereof, said hydrotrope being substantially anhydrous .

3. A process of making a laundry detergent bar, which process comprises the steps of:

(a) Supplying substantially anhydrous dodecyl benzene sulfonic acid to a reaction vessel;

(b) Neutralizing said sulfonic acid with substantially anhydrous granular sodium carbonate to form sodium dodecyl benzene sulfonate;

(c) Blending sodium tripolyphosphate with said sulfonate;
and (d) Preparing said detergent bar from the thus-formed mixture of tripolyphosphate and sulfonate;

wherein said bar comprises from about 5% to about 50% by weight sodium dodecyl benzene sulfonate and from about 5% to about 60%
sodium tripolyphosphate; and wherein any water blended with said sodium dodecyl benzene sulfonate subsequent to said neutralizing step is in the form of water of hydration of an inorganic salt.

4. The laundry detergent bar formed by the process of Claim 1, 2, or 3.