Free flowing nonionic surfactants

Abstract

A method for converting liquid nonionic surfactants to dry free flowing form is disclosed. The new method includes the mixing of the liquid nonionic material with specific particulate carrier materials in amounts varying from 30 to 85 percent. Suitable carrier materials include compounds having functional properties in detergent formulations. The free flowing nonionic surfactant-carrier pre-mix is very suitable for post-addition to spray dried detergent formulations in order to increase their content of nonionic surfactant.

Parent Case Text

Related Applications

This application is a continuation-in-part of copending application Ser. No. 114,073 filed Feb. 9, 1971 and entitled Free Flowing Nonionic Surfactants, and now U.S. Pat. No. 3,769,222 issued Oct. 30, 1973.

Description

The invention pertains to heavy duty particulated detergent formulations that include anionic, cationic, or nonionic surface active agents and detergent builders. More specifically the invention provides heavy duty detergents having a relatively high content of nonionic surface active agent.

The most commonly used surface active agents in heavy duty detergent formulations are anionic compounds having detersive properties. Typical of these anionic compounds are the higher alkyl mononuclear aromatic sulfonates such as the higher alkyl benzene sulfonates. These synthetic detergents are very effective in removing dirt from textile fabrics when utilized in conjunction with phosphate builders which function to "soften" the water being used and to provide detersive action. However, considerable controversy exist today as to the efficacy of utilizing phosphate compounds in detergent formulations due to their alleged causation of the eutrophication process in lakes, rivers and streams. Although the eutrophication process, wherein an excessive growth of plant life is promulgated in natural water bodies, is not completely understood, it is alleged that the phosphate compounds present in detergent containing waste water are a prime factor in promoting this phenomenon.

Although nonionic surfactants are not as effective as anionic surfactants in the presence of large amounts of phosphate builders, it has been discovered that when the phosphate content of a detergent formulation is substantially reduced, the nonionic surfactants appear to provide detergency properties that are superior to anionics in the same reduced phosphate content formulation. Apparently the detersive effectiveness of nonionic surfactants is affected much less by water hardness than that of the commonly used anionic surfactants. In the event that phosphate builders are totally or partially removed from detergents, the incorporation of greater and greater amounts of nonionic surfactants into detergent formulations will become very desirable.

At present, small amounts of nonionic surfactants are added to detergent formulations, primarily to reduce the amount of foam generated during the washing cycle. The most commonly used nonionic surfactants are long carbon chain alcohols ethoxylated with ethylene oxide. Typically, the nonionic ethoxamer used has a 12 to 18 carbon atom alkyl chain and an average of about 10 to 19 ethylene oxide units. The range of ethylene oxide content that provides the greatest detergency in these surfactants usually results in a nonionic material that is a viscous liquid at room temperature and therefore unsuitable for direct addition to the dry detergent powder. However, it has been found that when a substantial amount, typically above about 5% by weight, of nonionic surfactant is incorporated into the detergent slurry before spray drying, a significant air pollution problem is encountered. This problem, known in the industry as "pluming", is manifested as a dense black smoke being discharged from the spray tower.

The primary objective of the present invention is to provide a method for converting liquid nonionic surfactants to dry free flowing particulate form so that they may be post added to spray dried detergent formulations and thereby significantly increase the nonionic surfactant content of the final detergent product. The maximization of the nonionic surfactant content of the post addable free flowing powder and the selection of particularly suitable carriers for the nonionic materials are important further objectives of the invention.

The present invention provides a method for obtaining free flowing particulate materials having a nonionic surfactant content of up to about 85% by weight, and preferably above 30% by weight, and most preferably, between 62 and 85% by weight. The new materials are very suitable for post addition to spray dried detergent powders in order to substantially raise the nonionic surfactant content of the finished detergent product. In order to achieve an optimum post additive mixture for spray dried detergent fomulations, it is desirable to maximize the loading of nonionic surfactant on the chosen carrier and also to choose carriers that contribute to the efficacy of the detergent product. The invention provides a specific carrier materials for nonionic surfactants that are capable of high nonionic loadings; some of which also contribute functional characteristics to the detergent formulation.

In accordance with the invention, it has been found that particulate silica substances in general, and microsized silicon dioxide particles in particular, are capable of carrying a high loading (about 85% by weight) of nonionic surfactant without losing their free flowing characteristics. Pursuant to this aspect of the invention, a method for preparing free flowing particulate premix, including a high loading, preferably from 62 to about 85% by weight, most preferably about 65 to 75% by weight, of liquid nonionic surface active agent and microsized silica particles is provided. The premix is particulary suitable for addition to a detergent powder formed by spray drying a detergent slurry according to well known procedures, to produce a final formulation having a desirably high content of nonionic surface active agent. The premix is advantageously produced by mixing the nonionic with a sufficient amount of microsized silica particles to result in a free flowing powder. The amount of microsized silica particles used to solidify the nonionic into free flowing form is above 5% by weight of the mixture, usually between more than about 5% by weight up to about 38%, preferably about 25%, by weight.

Since microsized silicon particles are used as an anti-caking agent in some detergent formulations, its use as a liquid nonionic carrier provides anti-caking properties as well as higher nonionic content to the detergent formulation it is ultimately combined with. Further the aforementioned silica substances, when added to a mixture of nonionic surfactant and other carriers, in accordance with the invention, substantially increases the maximum nonionic loading of the resulting post addable, free flowing mix.

Other desirable carriers for liquid nonionic surfactants are substances having building properties in the detergent formulations. In view of the desirability of reducing, and if possible eliminating, the phosphate content of detergent formulations, the use of other builders in conjunction with a higher concentration of nonionic surfactant is advantageous. In this regard it has been found that certain non-phosphate detergent builders are suitable carriers for liquid nonionic surfactants. Representative of these builder-carrier substances are the sodium salts of nitrilotriacetic acid (NTA), sodium carbonate and sodium citrate. Loadings of up to about 50% by weight of nonionic surfactant have been obtained with these builder-carriers either individually or in combination with each other in multi-component systems. The nonionic loading of these builder-carriers can be increased to over about 60 weight percent by adding a small amount, typically about 5 percent by weight, of a silica substance, preferably microsized silicon dioxide particles to the blend. Although pyrogenic microsized silicon dioxide particles are preferred in the practice of the invention other microsized silicon dioxide particles such as silica gel and diatomaceous silica have given satisfactory results.

In further accordance with the invention, certain peroxygen bleaching agents have been found to be suitable carriers for nonionic surfactants while still retaining their free flowing properties. Peroxygen bleaching agents are advantageous carriers for liquid nonionic surfactants when it is also desirable to include a bleaching component in the final formulation. This is particularly so when only one post addition operation can be performed since both post additives can be added simultaneously in accordance with this aspect of the invention.

In the following examples maximum loadings of liquid nonionic surfactant were applied to various particulate carriers. The maximum loading was determined by adding increasing amounts of nonionic to a given amount of carrier until the resulting mixture could not be solidified into a free flowing powder. In examples 1-14 the nonionic surfactant utilized was an ethoxylated long chain alcohol having a chain of 12 to 16 carbon atoms and 10 to 12 ethylene oxide units. A suitable ethoxamer is available from the Shell Chemical Company under the trademark NEODOL 45-11. NEODOL 45-11, according to its manufacturer, is a 14 to 15 carbon chain ethoxylated fatty alcohol having an average of 11 ethylene oxide units. The microzied silica particulate material used is available under the trademark Cab-O-Sil, grade EH-5 from the Cabot Company. Cab-O-Sil is a sub-microscopic particle size silica prepared by vapor phase hydrolysis of silicon tetrachloride at 1100.degree.C. All experimental runs were made at room temperature and atmospheric pressure. Other suitable microsized silica materials are available under the following trademarks: silica aerogel available from the Monsanto Chemical Company, Quso which is a precipitated silica which has a surface area of about 325 square meters per square meters per gram and Syloid 244, which is a low density gel available from W. R. Grace Company.

Example 1

Fifty grams of molten nonionic surfactant was heated to slightly above room temperature until clear appearance and then sprayed onto 10 grams of colloidal pyrogenic silicon dioxide. The resulting mixture was a free flowing powder having a nonionic loading of 83.3% by weight. The following techniques were used.

1. The liquid nonionic was sprayed onto a laboratory dish containing the silicon dioxide carrier and mixed with a spatula to produce a free flowing powder.

2. The liquid nonionic surfactant was sprayed into an air filled plastic bag in which the silicon dioxide particles were suspended by air currents.

3. The liquid nonionic surfactant was sprayed into a twin shell rotating blender containing the silicon dioxide particles.

The solidification mechanism of the foregoing procedures is believed to involve the coating of the liquid surfactant particles by the microscopic silicon dioxide particles rather than the absorption or adsorption of the liquid by the particles.

The free flowing powder produced by the foregoing method can be post added to spray dried detergent powders or, detergent builders and other detergent ingredients can be added to the nonionic powder to produce a finished detergent formulation.

An example of the latter procedure is to first prepare a free flowing powder consisting of 250.0 grams of a liquid nonionic surfactant and 50.0 grams of silicon dioxide carrier (83.3 weight percent nonionic). To this blend 100.0 grams of sodium salts of (NTA) and 100.0 grams of sodium citrate when added and blended to produce a finished deterent formulation having the following approximate composition:

nonionic surfactant 50 weight percent silicon dioxide 10 weight percent sodium salt of NTA 20 weight percent sodium citrate 20 weight percent

This later formula can be utilized as a detergent itself or as an additive to other detergent systems.

Example 2

The liquid nonionic surfactant was slowly added to a laboratory mortar containing any one or a combination of the following inorganic particulate materials: sodium carbonate, clays (such as bentonite and zeolite), diatomaceous earth (Celite Filteraid available from Johns-Manville Company) or aluminum oxide. Upon blending the liquid nonionic and the inorganic particulate material with a pestle, partial solidification of the mixture occurs. Upon setting at room temperature for about one hour a free flowing powder is obtained.

Using the foregoing method, liquid nonionic loadings as high as 50% by weight can be obtained without impairing the flowability of the resulting solid particulate material.

Example 3

Colloidal pyrogenic silicon dioxide, in various amounts, was thoroughly mixed into the partially solidified mixture of Example 2 before final setting. Nonoinic surfactant loadings of from 50 to 80 weight percent (based on the total inorganic content) were obtained when from about 5 to 25 percent by weight pyrogenic silicon dioxide was added to the mixture. Representative free flowing compositions obtainable by this method are:

nonionic 58.9 weight percent bentonite 23.5 " SiO.sub.2 17.6 " 100.0 nonionic 60.0 weight percent sodium carbonate 35.0 " SiO.sub.2 5.0 " 100.0

Example 4

From 50 to 80 weight percent of the liquid nonionic surfactant was blended with a mixture of 15 to 45 weight percent of an organic nitrogenous compound chosen from the group consisting of melamine, glycine and iminodiacetic acid and from 0 to 50 percent by weight of any one or a mixture of the inorganic carriers of Example 2. Upon mixing, partial solidification occurs. The addition of at least 5 percent by weight of colloidal pyrogenic silicon dioxide and subsequent thorough blending results in solidification of the mixture. The solidified mixture can be broken up into a free flowing, non-caking powder. The following free flowing powder compositions have been obtained by the foregoing method:

(1) nonionic 63.6 weight percent melamine 18.1 " SiO.sub.2 18.3 " (2) nonionic 70 weight percent sodium salt of glycine or imino- 20 " diacetic acid SiO.sub.2 10 " (3) nonionic 80 weight percent sodium salt of 3 " glycine or imino- diacetic acid bentonite 7 " SiO.sub.2 10 " (4) nonionic 80 weight percent sodium salt of 10 " glycine or imino- diacetic acid SiO.sub.2 10 " (5) nonionic 80 weight percent sodium salt of 3 " glycine or imino- diacetic acid SiO.sub.2 15 "

Example 5

The procedures and compositions of Example 4 were followed except that a non-nitrogenous organic material chosen from the group consisting of sodium glycolate, glycolic acid, sorbitol, and potassium sodium tartrate, was substituted for the nitrogen containing organic compounds. The following free flowing powder formulations were obtained by the foregoing method:

(1) nonionic 50 weight percent bentonite 30 " sodium glycolate 10 " SiO.sub.2 10 " (2) nonionic 60 weight percent zeolite 13 " sodium glycolate 10 " SiO.sub.2 17 " (3) nonionic 66.6 weight percent potassium sodium 16.8 " tartrate SiO.sub.2 16.6 " (4) nonionic 50 weight percent sorbitol 24 " SiO.sub.2 26 " (5) nonionic 70 weight percent glycolic acid 10 " SiO.sub.2 20 " (6) nonionic 80 weight percent sodium glycolate 8 " bentonite 2 " SiO.sub.2 10 " (7) nonionic 70 weight percent sodium glycolate 20 " SiO.sub.2 10 " (8) nonionic 70 weight percent sodium glycolate 10 " aluminum oxide 10 " SiO.sub.2 10 "

Example 6

The liquid nonionic surfactant was mixed with trisodium nitrilotriacetate and sodium citrate-2H.sub.2 O. Partial solidification occurred on mixing. Pyrogenic silicon dioxide was then added and thoroughly mixed with the partially solidified mass. Full solidification of the mixture occurred. The resulting solid was then broken up into a free flowing, non-caking powder. The following composition has been obtained by the foregoing method:

nonionic surfactant 56.6 weight percent sodium salt of NTA 13.0 " sodium citrate 13.0 " SiO.sub.2 17.4 "

The resulting free flowing powder is very suitable for post addition to a spray dried detergent powder. Similar free flowing powder can be obtained without the addition of SiO.sub.2 by reducing the nonionic content to about 30 percent by weight.

Example 7

The liquid nonionic surfactant was mixed with sodium carbonate and the sodium salt of NTA. Partial solidification occurs on mixing. Pyrogenic silicon dioxide was then added and thoroughly blended with the partially solidified mass. Full solidification of the mixture resulted. The resulting solid was then broken up into a free flowing non-caking powder.

The following composition has been obtained by the foregoing method:

nonionic surfactant 60.0 weight percent sodium salt of NTA 15.0 " sodium carbonate 15.0 " SiO.sub.2 10.0 "

The resulting free flowing powder is very suitable for post addition to a spray dried detergent powder.

Example 8

35 weight percent of liquid nonionic surfactant is blended together with 65 weight percent sodium perborate monohydrate. The resulting mixture is a free flowing powder suitable for post addition to spray dried detergent formulations.

Attempts to use sodium perborate tetrahydrate as a carrier for the liquid nonionic yielded a tacky non-flowable powder with a nonionic liquid content of about 20 percent by weight.

Example 9

A free flowing particulate material having a nonionic surface active agent content of 68% by weight can be prepared by the following procedure: 68 grams of Neodol 45-11 was heated to slightly above room temperature until molten and clear in appearance. The molen nonionic surface active agent was slowly added to 32 grams of Cab-O-Sil EH-5, a micro-sized silica powder, and the combination was mixed by mechanical stirring for about 5 minutes. The resulting product is a free flowing powder.

Example 10

The procedure of Example 9 can be repeated using 62 grams of Neodol 45-11 and 38 grams of Cab-O-Sil EH-5 to produce a free flowing powder having a nonionic loading of 62% by weight.

Example 11

The procedure of Example 9 is repeated using 75 grams of Neodol 45-11 and 25 grams of Cab-O-Sil EH-5 to produce a free flowing powder having a nonionic loading of 75% by weight.

The free flowing products produced by Examples 9-11 are ideally suitable for post addition to a detergent powder made by spray drying a detergent slurry according to well known procedures in the detergent art. Final detergent formulations produced by combining spray dried detergents with the free flowing particulate pre-mixes of the invention can comprise from about 10 to about 50% of the post-added premix component to provide a wide range of nonionic content depending on the nonionic loading of the premix and the requirements of the particular application.

Example 12

320 grams of a particulate silica material sold under the trademark Santocel, which is a silica aerogel, was introduced into a Hobart mixer. The stirrer was turned on (low speed) and 680 grams of a nonionic surface active agent (Neodol 45-11) in molten form was slowly poured onto the silica material over a period of about 2 minutes. Sirring was continued for another 5 minutes at low speed. The resulting product was a free flowing particulate material having a nonionic loading of 68% by weight.

Example 13

The procedure of Example 12 was repeated using a particulate silica material available under the trademark Quso. Quso is a precipitated silica having a surface area of 325 m.sup.2 /gram and a 5% water content. The resulting product was a free flowing particulate material having a nonionic loading of 68% by weight.

Example 14

The procedure of Example 12 was repeated using a particulate silica material available under the trademark Syloid 244. Syloid 244 is a low density silica gel. The resulting product is a free flowing particulate material having a nonionic loading of 68% by weight.

Runs similar to Examples 1-14 can be made using liquid nonionic surfactants having a longer alkyl chain than Neodol 45-11, i.e. 16-18 carbon atoms, and a higher ethylene oxide content, i.e. an average of 19 ethylene oxide units. A suitable liquid nonionic meeting these requirements is available from the Continental Oil Company under the trademark Alfonic 1618-78. It was found that, Alfonic 1618-78 can be solidified with less effort, i.e. in less time, than Neodol 45-11 and to approximately the same loadings.

Functional carriers that can be heavily loaded with nonionic surfactants and still remain free flowing, non-caking powders were found to include pyrogenic silicon dioxide, which functions as an anti-caking agent in the final formulation, and various detergent builders such as NTA, sodium carbonate and sodium citrate. When it is desired to incorporate a peroxygen bleach component into the detergent formulation, in addition to a nonionic surfactant component, it has been found that sodium perborate monohydrate is a surprisingly good carrier for the nonionic component since both can thereby be added in one post addition operation. Further, the addition of a small amount of pyrogenic silicon dioxide to mixtures of liquid nonionic surfactant and carrier material have been found to significantly increase the nonionic loadings of the post addable mixture while still retaining the necessary free flowing characteristics.

Although phosphate detergent builders have also been found to be very suitable carriers for liquid nonionic surfactants, their use is not preferred at this time because of the alleged contribution of phosphates to the eutrophication process in natural bodies of water. However, in reduced phosphate content detergent formulations, all or part of the phosphate builder can be added to the formulation subsequent to spray drying as a carrier for nonionic surfactants. In this regard, it has been found that phosphate builders, such as the sodium tripolyphosphate can be loaded with up to about 30 percent by weight liquid nonionic surfactant while still retaining free flowing properties. In accordance with the invention the nonionic loading on phosphate carriers can be increased to about 50 percent by weight by adding about 5 percent by weight of a microsized silica substance to the nonionic-carrier mixture before final setting.

By providing a commercially feasible method for post adding liquid nonionic surfactants to spray dried detergent formulations, the invention represents a significant step towards the substantial reduction of phosphate builders from detergent formulations without a significant decrease in cleaning efficacy.

Although the foregoing specific embodiments are presently preferred, they should not be considered as limiting the invention. Accordingly reference should be made to the following claims to determine the full scope of the invention.

Claims

We claim:

1. In the method of preparing a heavy duty detergent which includes the step of spray drying a detergent slurry to form a dry, free flowing powder, the improvement comprising adding to said spray dried powder a free flowing premix consisting of from 62 to 85 percent by weight of a liquid nonionic surface active agent chosen from the group consisting of ethoxylated alcohols having a 12 to 18 carbon atom chain and an average of from 10 to 19 ethylene oxide units and at least 5% by weight of microsized silica particles, said premix being prepared by mixing said liquid nonionic with a sufficient quantity of silica particles to fully solidify said liquid nonionic.

2. The improved method of claim 1, wherein said premix contains from about 65 to about 75% by weight of said nonionic.

3. The improved method of claim 1, wherein said micro-sized silica particles are chosen from the group consisting of silica gels, silica aerogels, precipitated silicas and pyrogenic silicas.

4. The free flowing particulate product produced by the method of claim 1.