US3472784A - Detergent process - Google Patents

Description

United States Patent 3,472,784 DETERGENT PROCESS Russell W. Poe, Kirkwood, Mo., assignmto Monsanto Company, St. Louis, Mo., a corporation of Delaware No Drawing. Filed Sept. 30, 1966, Ser. No. 583,468 Int. Cl. Clld 3/06 US. Cl. 252-138 7 Claims ABSTRACT OF THE DISCLOSURE A free-flowing particulate detergent composition is prepared by mixing a liquid acid form of an anionic surfactant with a water soluble alkaline material; adding sufficient water to provide a mixture containing from about 0.5% to about 4.0% by weight free water; and thereafter adding hydratable sodium tripolyphosphate to the mixture.

This invention relates to processes for the manufacturing of detergent compositions. More particularly, it relates to processes for manufacturing detergent compositions containing an anionic surface active agent and sodium tripolyphosphate.

The more commonly used anionic surface active agents include the alkyl aryl sulfonic acids, alkyl sulfonic acids, alkyl sulfuric acids, fatty acids, and polyethylene oxide ether sulfuric acids, and their water soluble salts. When formulated into detergent compositions, normally the water soluble salts are used. While the foregoing surface active agents are produced in a variety of methods, in most instances the acid is produced by sulfonating or sulfating a compound, such as alkylated benzene, with one of the well-known sulfonating and sulfating agents such as S0 oleum, and sulfuric acid. The acid is thereafter converted to a water soluble salt generally by reacting the acid with bases such as the alkali metal hydroxides or with basic salts such as the alkali metal carbonates. In conventional detergent manufacturing, the water soluble salt of the anionic surface active agent is slurried with the various detergent additives such as sodium tripolyphosphate, sodium silicate, sodium sulfate, and the like, and thereafter spray dried.

In some instances, it is advantageous to eliminate the slurrying and spray drying step and still produce granular detergents. This can be done by admixing a dried water soluble salt of the acid with the other detergent additives but a separate neutralization and drying step is necessary to obtain such dried water soluble salt of the anionic. Such admixtures have a tendency to undergo particle segregation since the various detergent composition ingredients have varying particle sizes and densities.

It is known to react an anionic surface active agent in its acid form with a solid particulate alkaline salt to thereby produce a detergent composition. This process is generally conducted by spraying the liquid acid form of the anionic surface active agent onto an agitated bed of the commonly used alkaline detergent additives such as the alkali metal phosphates, silicates, carbonates, and the like. When producing granular ,detergent compositions by this method, it is generally necessary to dry the composition and subject it to milling and screening. It is believed, therefore, that a process that would enable the production of a dry, free-flowing granular detergent composition from the liquid acid form of an anionic surface active agent which detergent compositions do not segregate even upon prolonged handling and which process does not require spray drying, air ,drying, or milling steps would be an advancement in the art.

In accordance with this invention, it has been found that free-flowing, non-segregating, detergent compositions 3,472,784 Patented Oct. 14, 1969 can be prepared by (a) mixing together a liquid acid form of an anionic surface active agent and a water soluble solid alkaline material capable of reacting with said acid to form a water soluble salt of said acid, (b) adding to the resulting mixture from 0 to about 4% by weight of water based upon the overall weight of the mixture to provide a free water content in the mixture of from about 0.5% to about 4% and (c) thereafter adding to said mixture from about 5% to about 35% by weight of particulate hydratable sodium tripolyphosphate based upon the total weight of the detergent composition.

It is believed surprising that a free-flowing detergent composition can be produced in the above manner because anhydrous sodium tripolyphosphate is one of the water soluble alkaline materials that can be utilized to convert the liquid acid form of the anionic surface active agent into a water soluble salt but if from about 5% to about 35% by weight of particulate hydratable sodium tripolyphosphate based upon the total weight of the detergent composition is not added after at least a portion of the surface active agent is converted to a water soluble salt of the acid, a wet dough-like product is formed instead of a dry, free-flowing detergent composition.

Anionic surface active agents are well known in the art and examples of these are found in Schwartz and Perry and Berch, Interscience Publishers, Inc. New York (1958). As was previously mentioned the alkyl aryl sulfonic acids are useful in the practice of this invention and generally contain an aryl group selected from the group consisting of benzene, naphthalene, lower alkyl substituted benzene, and lower alkyl substituted naphthalene. The alkyl group, attached to the aryl group, generally is a higher alkyl group; that is, containing from about 6 to about 30 carbon atoms and can be branched or straight chain.

Examples of alkyl aryl sulfonic acids which can be utilized in the practice of this invention include dodecyl benzene sulfonic acid, tridecyl benzene sulfonic acid, tetradecyl sulfonic acid, decyl naphthylene sulfonic acid, nonyl toluene sulfonic acid, tetracosyl benzene sulfonic acid and the like.

The alkyl sulfonic acids typical of those useful in the practice of this invention generally contain from about 8 to about 20 carbon atoms. The alkyl portion can be branched or straight chain. Typical examples include dodecyl sulfonic acid, tetradecyl sulfonic acid, octyl sulfonic acid, and eicosyl sulfonic acid. The alkyl sulfuric acids which can be utilized are similar in structure to the alkyl sulfonic acid except that a sulfuric acid group instead of a sulfonic acid group is present.

The =polyethylene ether sulfuric acids are generally prepared by sulfating the condensation product of ethylene oxide with alkyl phenol or a higher aliphatic alcohol. The alkyl portion of the alkyl phenol generally contains from about 6 to about 20 carbon atoms. When a higher aliphatic alcohol is condensed with ethylene oxide, the alcohol generally will contain from about 6 to about 30 carbon atoms. Usually from about 3 to about 30 moles of ethylene oxide per mole of alkyl phenol or higher aliphatic alcohol are used. The alkyl groups can be either branched or straight chain. Illustrative of the ethylene oxide ether sulfuric acids useful in the practice of this invention include those produced by the sulfonation of the condensation product of 9 moles of ethylene oxide per mole of dodecyl alcohol; the sulfonated condensation product of 8 moles of ethylene oxide per mole of tridecyl alcohol and the sulfonated product obtained from condensing 3 moles of ethylene oxide per mole of tetradecyl alcohol.

The fatty acids, typical of those useful in this invention generally, contain mixtures of acids having from about 8 to about 20 carbon atoms as, for example, coconut oil acid, oleic acid, tallow acid, and the like.

It is to be noted that as used herein, the materials are stated as having a number of carbon atoms; however, in most instances, these materials will be a mixture of compounds having a varying number of carbon atoms in their chain but averaging the number as herein specified. The before-mentioned surface active agents will generally be a mixture of the acids with water and sulfuric acid. In most instances, the amount of water will not exceed about 5% by weight of the total liquid mixture although surface active agents containing from about 5% to about 15% by weight of water can be used. It is generally preferable to utilize those liquid acid forms which contain even lower amounts of water, that is below about 5% by weight. Anionic surface active agents are employed in amounts of from about 1% to about 50% by weight based upon the total weight of the detergent compositions. The allowable amount of water which can be present in the liquid mixture is dependent upon the amount of surface active agent that is used, therefore, the amount of water that is subsequently added will vary from to 4%. For example, if it is desired to prepare a detergent composition containing about 10% anionic and the liquid mixture contains about 3% water it would be necessary to add from about 0.2% to about 3.7% by weight of water based upon the weight of the mixture after the mixture of anionic and water soluble alkaline material is prepared. The remaining portion of most detergent compositions is comprised of inorganic builders such as the alkali metal polyphosphates, organic builders such as the alkali metal polyphosphates, organic builders such as the alkali metal salts of nitrilopolycarboxylic acid, corrosion inhibitors such as sodium metasilicate and sodium fluorosilicate, and inert fillers such as sodium sulfate, carbonates, and the like. It is preferable in most instances to use from about 5% to about 25% by weight of the anionic surface active agent based upon the total weight of the detergent composition.

Any water soluble solid alkaline material that will react with the liquid acid form of the anionic surface active agent to form a water soluble salt of the anionic surface active agent can be utilized in the practice of this invention to convert at least a portion of the liquid acid to its water soluble salt. Water soluble as used herein means that at least 1 gram of the alkaline material will dissolve in 100 cc. of water at 25 C. Alkaline is used in its generally accepted sense, that is, that an aqueous solution of the material has a pH greater than 7.0. It is generally preferred, however, since most detergent formulations include alkali metal inorganic alkaline salts, that is the alkali metal carbonates, tripolyphosphates, orthophosphates, pyrophosphates, trimetaphosphates, silicates, and borates, they are preferred in the practice of this invention. It is possible, however, to utilize any water soluble solid alkali metal base in the practice of this invention, such as sodium and potassium hydroxide. Since the most commonly used detergent additives are the alkali metal polyphosphates, carbonates, borates, and silicates, it is preferred to utilize at least one of these inorganic alkali metal alkaline salts as a water soluble alkaline material in the practice of this invention. Of these the sodium salts are especially preferred.

It is preferred that there be enough water soluble alkaline material present in the mixture of the anionic surface active agent and water soluble alkaline material to convert essentially all of the acid form of the anionic surface active agent to the water soluble salt thereof prior to adding from about 5% to about 35% by weight based upon the weight of the detergent composition of hydratable sodium tripolyphosphate. If desired, however, as little as 50% or even less such as of the molar equivalent amount of solid water soluble alkaline material can be used because all of the acid does not have to be converted to the water soluble salt prior to adding the hydratable sodium tripolyphosphate. In most instances, it is preferred that from to about 300% of the molar equivalent amount of water soluble alkaline material theoretically required to react with the acid be present in the mixture of alkaline material and anionic surfactant.

It is necessary that there be at least some free water in the mixture of the liquid acid form of the anionic surface active agent and water soluble solid alkaline material to achieve the benefits of this invention. It is believed that the water is necessary to trigger the neutralization; however, this invention is not to be limited by this theory of operation. Rather it is to be interpreted as that this presence of the specified amounts of water are needed to produce the product as specified herein. Amounts of from about 0.5 to about 4% by Weight of free water, preferably from 1% to 3% by weight, based on the total weight of the mixture, need to be present in order to enable the production of a free-flowing, non-segregating detergent composition. The water can be incorporated by using an acid surface active agent which contains, in addition to the acid, from about 5 to about 15 water. In most instances, it is preferred to use an active containing less water, that is, from about 0% to about 5% then adding the amount of water necessary to achieve the above specified level after the mixture of active and water soluble alkaline material has been formed. It is, therefore, preferred that the liquid acid form contain less than about 5% water and that about 1 to about 3% water be added after the mixture of the acid and the water soluble solid alkaline material is formed. When there is water present in the active, only an amount of active which will yield a water content of a maximum of about 4% can be used. Free water as used herein means water that is other than that which is bound as water of hydration in the water soluble alkaline material prior to the adding of the anionic.

Although nearly any form of commercial particulate hydratable sodium tripolyphosphate can be used in the practice of this invention, it is generally preferred to use at least 50% of the total hydratable sodium tripolyphosphate that has a relatively small particle size, that is smaller than the openings in a U.S. Standard 60 mesh screen and even more preferably to have a particle size less than the openings in the U.S. Standard mesh screen.

Although all of the hydratable sodium tripolyphosphate added can pass through a U.S. Standard 100 mesh screen, one of the preferred embodiments of this invention is to add from about 5 to about 15% by weight of the total detergent composition of a hydratable sodium tripolyphosphate that has a particle size such that at least 90% will pass through a U.S. Standard 40 mesh screen and be retained on a U.S. Standard 100 mesh screen then subsequently add an additional 5 to 15% by weight based on the total weight of the detergent composition of a hydratable sodium tripolyphosphate having a particle size such that about 90% will pass through a U.S. Standard 100 mesh screen. It has been found that this preferred embodiment of this invention produces a relatively high amount, that is, in excess of 80% of particles having a size suitable for most detergent purposes.

The improvement of this invention is independent of the particular form of hydratable sodium tripolyphosphate that is used; that is, either Form I or Form II of anhydrous sodium tripolyphosphate can be used although it is preferable to use a material which will hydrate at a relatively high rate. Although rates of hydration of sodium tripolyphosphate are dependent upon several factors, Form I sodium tripolyphosphate hydrates faster under similar conditions than Form II. Therefore, sodium tripolyphosphate containing amounts, in excess of about 15% of Form I sodium tripolyphosphate are preferred. It is also to be noted that although anhydrous sodium tripolyphosphate is preferred, a partially hydrated sodium tripolyphosphate can be used to achieve benefits of this invention. It is necessary, however, that the sodium tripolyphosphate be capable of being hydrated; therefore, the hexahydrate, the highest hydrated form of sodium tripolyphosphate, cannot be used successfully in the partice of this invention.

In some instances, it may be desired to incorporate nonionic surface active agents into the detergent formulation. When nonionic surface active agents are desired in the formulation, it is necessary to add them after the mixture of anionic surface active agent and water soluble solid alkaline material has a free water content of 0.5 to about 4% by weight. Adding the nonionic prior to this point in the process tends to coat the particles thereby retarding neutralization and yielding products having undesirable flow properties. Nonionic surface active agents are well known in the art and examples can be found in Schwartz, Perry, and Berch, Interscience Publishers, Inc., New York (1958). Typical examples of nonionics useful in the practice of this invention include those which are made by reacting an alkylene oxide such as ethylene oxide, butylene oxide, propylene oxide and the like with fatty acids, a straight or branched chain alcohol, phenols, thiophenols, amides and amines to form polyoxyalkylene glycol ethers and esters, polyoxyalkylene alkyl phenol and polyoxyalkylene thiophenols, and polyoxyalkylene amides and the like. It is generally preferred to react from about 3 to about 30 moles of alkylene oxide per mole of the fatty acids, alcohols, phenols, thiophenols, amides or amines. Compounds illustrative of the synthetic nonionic surface active agents include the products obtained from condensing ethylene oxide or propylene oxide with the following: propylene glycol, alcohol, N-octadecyl diethanolami de, and N-dodecyl monoethauolamide. When nonionic surface active agents are used, it is generally preferred to use from about 2% to about 5% by weight based upon the total weight of the detergent composition, larger amounts such as and even can be used if desired.

The following examples illustrating specific embodiments of this invention are presented. All parts and proportions are by weight unless otherwise indicated.

EXAMPLE 1 About 100 parts of anhydrous sodium tripolyphosphate, about 270 parts of sodium carbonate, about 40 parts of sodium metasilicate and about 8 parts of sodium carboxymethylcellulose are charged into a ribbon mixer. While the contents are being agitated, about 120 parts of dodecylbenzene sulfonic acid, containing about 94% by weight of dodecyl benzene sulfonic acid, about 1.5% sulfuric acid, about 2.8% unsulfonated material and about 1.7% Water are sprayed upon the contents of the ribbon mixer within about 10 minutes. After the addition of the dodecylbenzene sulfonic acid is completed about 16 parts of water are added and the contents are allowed to mix for about 5 minutes forming a wet, dough-like mixture. About 220 parts of anhydrous sodium tripolyphosphate, having a particle size such that about 95% passes through a US. Standard 100 mesh screen and about 70% passes through a US. Standard 270 mesh screen, are blended into the dough-like mixture within about 10 minutes. Within about 5 minutes after all of the anhydrous sodium tripolyphosphate is added, a dry free-flowing detergent material is produced. The product is screened and is packaged for use as heavy duty laundry detergent and shows no appreciable particle segregation even upon repeated handling.

EXAMPLE 2 About 300 parts of tetrasodium pyrophosphate, 200 parts of sodium carbonate, 60 parts of sodium metasilicate, 10 parts of sodium carboxymethylcellulose and 30 parts of trisodium nitrilotriacetate are charged into a ribbon mixer as in Example 1. While agitating about 100 parts of octadecyl benzene sulfonic acid and about 100 parts of dodecyl benzene sulfonic acid containing less than about 3% water are added to the contents of the ribbon mixed within about 8 minutes. After the octadecyl benzene sulfonic acid and dodecyl benzene sulfonic acid is added, about 20'parts of water are added to give a free water content in the mixture of about 1%. The contents of the ribbon mixer are allowed to mix for about 10 mintues and then about 50 parts of a granular anhydrous sodium tripolyphosphate having a particle size smaller than a U8. Standard 20 mesh screen and larger than a US. Standard 100 mesh screen are added and allowed to mix for about 5 mintues and then about parts of a powdered form of anhydrous sodium tripolyphosphate are added. The powdered sodium triployphosphate has 90% of its particles smaller than a US. Standard mesh screen and 70% smaller than a US. Standard 270 mesh screen. After about 5 minutes of mixing the contents of the ribbon mixer are free-flowing and can be screened and packaged as a heavy duty laundry detergent.

EXAMPLE 3 Following essentially the same process as in Examples 1 and 2, the following materials are added as the water soluble alkaline material: anhydrous sodium tripolyphosphate300 parts, sodium sulfate200 parts, sodium metasilicate50 parts, sodium carboxymethylcellulose-- 10 parts, pentasodium l-hydroxy ethylidene diphosphonate-l5 parts. After about 100 parts of tetradecyl benzene sulfonic acid, about 50 parts of dodecyl sulfuric acid, and 50 parts of the sulfonated condensation product obtained from the condensation of 9 moles of ethylene oxide per mole of nonyl phenol are sprayed upon an agitated bed of the before-mentioned water soluble alkaline material, about 30 parts of water are then added followed by about 50 parts of dodecyl ethylidene oxide ether sulfonic acid produced by the sulfonation of the condensation product of 9 moles of ethylene oxide permole of dodecyl alcOhol. After mixing for about 10 mintues, about parts of a powdered anhydrous sodium tripolyphosphate is added. The screen size of the anhydrous sodium tripolyphosphate is as follows:

About 10 minutes after the anhydrous sodium tripolyphosphate has been added, the wet, dough-like contents of the mixer are converted into a dry, free-flowing detergent composition.

What is claimed is:

1. A process for producing a free-flowing particulate detergent composition, said process comprising (a) mixing from about 5% to 25% by weight, based on the total weight of the detergent composition, of a liquid acid form of an anionic surface active agent selected from the group consisting of alkyl aryl sulfonic acid, alkyl sulfuric acid, alkyl sulfonic acid, fatty acids, and polyethylene ether sulfonic acids with an amount of water soluble alkaline material selected from the group consisting of alkali metal polyphosphates, borates, carbonates, silicates and mixtures thereof, at least theoretically sufficient to convert essentially all of the acid form of the surface active agent to a water soluble salt thereof; (b) adding to the resultant mixture from about 0 to about 4% by weight of water based upon the overall weight of said mixture to provide a free Water content of the mixture of from about 0.5% to about 4.0% by weight; and (c) thereafter adding particulate hydratable sodium tripolyphosphate to said mixture in amounts from about 5% to about 35% by weight based upon the total weight of the detergent composition.

2. A process according to claim 1 wherein said alkali metal is sodium.

3. A process according to claim 1 wherein said alkali metal is sodium, said hydratable sodium tripolyphosphate is an anhydrous sodium tripolyphosphate at least 20% by weight of which has a maximum particle size less than the openings in a U.S. Standard 60 mesh screen, and wherein from about 2% to 15% by weight, based upon the total weight of the detergent composition, of a nonionic surface active agent is added subsequent to step (b) and prior to step (c).

4. A process according to claim 3 wherein said nonionic surface active agent is added in amounts from about 2% to about 5% by weight based upon the total weight of the detergent composition.

5. A process according to claim 2 wherein said hydratable sodium tripolyphosphate is an anhydrous sodium tripolyphosphate and is added in amounts from about 10 to about 30% by weight based upon said detergent composition.

6. A process according to claim 5 wherein at least about 20% of said particulate hydratable sodium tripolyphosphate has a maximum particle size less than the openings in a U.S. Standard 60 mesh screen.

References Cited UNITED STATES PATENTS 2,874,123 2/ 1959 Schaafsma et a1. 25299 2,982,736 5/1961 Dvorkovitz et a1 252138 3,329,616 7/1967 Feierstein et a1. 252-138 MAYER WEINBLATT, Primary Examiner P. E. WILLIS, Assistant Examiner U.S. C1. X.R. 252l61