EP0876473B1

EP0876473B1 - Process for making a high density detergent composition from a surfactant paste containing a non-aqueous binder

Info

Publication number: EP0876473B1
Application number: EP96932960A
Authority: EP
Inventors: Scott William Capeci; David Robert Nassano
Original assignee: Procter and Gamble Co
Current assignee: Procter and Gamble Co
Priority date: 1995-09-14
Filing date: 1996-09-06
Publication date: 2006-06-28
Anticipated expiration: 2016-09-06
Also published as: AR003570A1; CA2232071A1; CN1202198A; CN1126811C; BR9610548A; WO1997010326A1; CA2232071C; DE69636309D1; DE69636309T2; MX9802022A; ATE331780T1; ES2263162T3; JPH11512473A; EP0876473A1

Description

FIELD OF THE INVENTION

The present invention generally relates to a process for producing a high density detergent composition. More particularly, the invention is directed to a continuous process during which high density detergent agglomerates are produced by feeding a surfactant paste with a non-aqueous binder and adjunct dry starting detergent material into two serially positioned mixer/densifiers. The process produces a high density detergent composition with unexpectedly improved flow properties which can be commercially sold as a low dosage or "compact" detergent composition.

BACKGROUND OF THE INVENTION

Recently, there has been considerable interest within the detergent industry for laundry detergents which are "compact" and therefore, have low dosage volumes. To facilitate production of these so-called low dosage detergents, many attempts have been made to produce high bulk density detergents, for example with a density of 650 g/l or higher. The low dosage detergents are currently in high demand as they conserve resources and can be sold in small packages which are more convenient for consumers.
Generally, there are two primary types of processes by which detergent granules or powders can be prepared. The first type of process involves spray-drying an aqueous detergent slurry in a spray-drying tower to produce highly porous detergent granules. In the second type of process, the various detergent components are dry mixed after which they are agglomerated with a binder such as a nonionic or anionic surfactant. In both processes, the most important factors which govern the density of the resulting detergent granules are the density, porosity and surface area of the various starting materials and their respective chemical composition. These parameters, however, can only be varied within a limited range. Thus, a substantial bulk density increase only can be achieved by additional processing steps which lead to densification of the detergent granules.
There have been many attempts in the art for providing processes which increase the density of detergent granules or powders. Particular attention has been given to densification of spray-dried granules by post tower treatment. For example, one attempt involves a batch process in which spray-dried or granulated detergent powders containing sodium tripolyphosphate and sodium sulfate are densified and spheronized in a Marumerizer®. This apparatus comprises a substantially horizontal, roughened, rotatable table positioned within and at the base of a substantially vertical, smooth walled cylinder. This process, however, is essentially a batch process and is therefore less suitable for the large scale production of detergent powders. More recently, other attempts have been made to provide a continuous processes for increasing the density of "post-tower" or spray dried detergent granules Typically, such processes require a first apparatus which pulverizes or grinds the granules and a second apparatus which increases the density of the pulverized granules by agglomeration These processes achieve the desired increase in density only by treating or densifying "post tower" or spray dried granules.
However, all of the aforementioned processes are directed primarily for densifying or otherwise processing spray dried granules. Currently, the relative amounts and types of materials subjected to spray drying processes in the production of detergent granules has been limited. For example, it has been difficult to attain high levels of surfactant in the resulting detergent composition a feature which facilitates production of low dosage detergents. Thus, it would be desirable to have a process by which detergent compositions can be produced without having the limitations imposed by conventional spray drying techniques.
To that end, the art is also replete with disclosures of processes which entail agglomerating detergent compositions. For example, attempts have been made to agglomerate detergent builders by mixing zeolite and/or layered silicates in a mixer to form free flowing agglomerates. While such attempts suggest that their process can be used to produce detergent agglomerates, they do not provide a mechanism by which starting detergent materials in the form of pastes, liquids and dry materials can be effectively agglomerated into crisp, free flowing detergent agglomerates having a high density. Further in this regard, previous agglomeration processes have significant room for improvement with respect to the flow properties of the agglomerates produced. Such flow properties which include free flowability, crispness, narrow particle size distributions and the like are necessary for modern day low dosage, compact detergent products. Additionally, previous agglomeration processes do not adequately account for, or are focused on minimizing the need for recycling undersized or over sized agglomerates produced from the process.
Accordingly, there remains a need in the art to have a process for continuously producing a high density detergent composition directly from starting detergent ingredients. Also, there remains a need for a process which produces such a high density detergent composition having improved flow properties and minimizes the need for recycling, Finally, there remains a need for such a process which is more efficient and economical to facilitate large-scale production of low dosage or compact detergents.

BACKGROUND ART

The following references are directed to densifying spray-dried granules: Appel et al. U.S. Patent No. 5,133,924 (Lever); Bortolotti et al. U.S. Patent No. 5,160,657 (Lever); Johnson et al. British patent No. 1,517,713 (Unilever); and Curtis, European Patent Application 451,894. The following references are directed to producing detergents by agglomeration: Beerse et al. U.S. Patent No. 5,108,646 (Procter & Gamble): Capeci et al, U.S. Patent No. 5,366,652 (Procter & Gamble); Hollingsworth et al. European Patent Application 351.937 (Unilever): and Swatling et al. U.S Patent No. 5.205.958. WO 93/25378 describes an agglomeration process for making high density granules for detergents.

SUMMARY OF THE INVENTION

The present invention meets the aforementioned needs in the art by providing a process which produces a high density detergent composition in the form of agglomerates directly from a surfactant paste and adjunct dry starting detergent ingredients. The surfactant paste has a relatively low amount of water, but retains its transportability and processability by including a sufficient amount of non-aqueous polyethylene glycol, having a melting point temperature of from 35 to 70°C, to which the formation of agglomerates having unexpectedly improved flow properties are attributed. As a consequence of these improved flow properties, the agglomerates exiting the instant process are less sticky and do not require recycling of oversized agglomerate particles back into the process to the extent of previous processes. The oversized agglomerate particles can be appropriately sized by more economical grinding processes subsequent to the instant process.
As used herein, the term "agglomerates" refers to particles formed by agglomerating more porous starting detergent ingredients (particles) which typically have a smaller median particle size than the formed agglomerates. All percentages and ratios used herein are expressed as percentages by weight (anhydrous basis) unless otherwise indicated. All viscosities referenced herein are measured at 70°C (±5°C) and at shear rates of about 1o to 100 sec^-1.
in accordance with one aspect of the invention, a process for preparing a crisp, free flowing, high density detergent composition is provided. The process comprises the steps of: (a) continuously mixing a detergent surfactant paste and dry starting detergent material into a high speed mixer/densifier to obtain detergent agglomerates, wherein the surfactant paste includes, by weight of the surfactant paste, from about 0.1% to about 50% of polyethylene glycol having a melting point temperature of from 35 to 70°C, introduced as non-aqueous polyethylene glycol, from about 30% to about 95% of a detersive surfactant, and the balance water; (b) mixing the detergent agglomerates in a moderate speed mixer/densifier to further densify and agglomerate the detergent agglomerates; and (c) drying the detergent agglomerates so as to form the high density detergent composition.
In an especially preferred embodiment of the invention, the process comprises the steps of: (a) continuously mixing a detergent surfactant paste and a dry starting detergent material comprising a builder selected from the group consisting of aluminosilicates, crystalline layered silicates, sodium carbonate, Na₂Ca(CO₃)₂, K₂Ca(CO₃)₂, Na₂Ca₂(CO₃)₃, NaKCa(CO₃)₂, NaKCa₂(CO₃)₃, K₂Ca₂(CO₃)₃, and mixtures thereof, into a high speed mixer/densifier to obtain detergent agglomerates, wherein said surfactant paste includes, by weight of said surfactant paste, from about 0.1% to about 50% of polyethylene glycol having a melting point temperature of from 35 to 70°C, introduced as non-aqueous polyethylene glycol, from about 30% to about 95% of a detersive surfactant, and the balance water, the weight ratio of the surfactant paste to the dry detergent material is from about 1:10 to about 10:1; (b) mixing the detergent agglomerates in a moderate speed mixer/densifier to further densify and agglomerate the detergent agglomerates; (c) drying the detergent agglomerates; and (d) adding a coating agent to obtain the high density detergent composition having a density of at least 650 g/l.
The invention also provides a high density detergent composition made according to the process of the invention and its various embodiments.
Accordingly, it is an object of the present invention to provide a process for continuously producing a high density detergent composition directly from a surfactant paste and adjunct dry starting detergent ingredients. It is also an object of the invention to provide such a process which produces a composition exhibiting improved flow properties. Also, it is an object of the invention to produce such a process which is more efficient and economical to operate on a large scale. These and other objects, features and anendant advantages of the present invention will become apparent to those skilled in the art from a reading of the following drawing, detailed description of the preferred embodiment and the appended claims.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present process is used in the production of low dosage detergent agglomerates directly from starting detergent ingredients rather than conventional "post-tower" detergent granules. By "post-tower" detergent granules, we mean those detergent granules which have been processed through a conventional spray-drying tower or similar apparatus. The process of the invention allows for production of low dosage detergents in an environmentally conscious manner in that the use of spray drying techniques and the like which typically emit pollutants though their towers or stacks into the atmosphere is eliminated. This feature of the process invention is extremely desirable in geographic areas which are especially sensitive to emission of pollutants into the atmosphere.

Process

In the first step of the process, the invention entails continuously mixing into a high speed mixer/densifier 10 several streams of starting detergent ingredients including a surfactant paste stream 12 and a dry starting detergent material stream 14. The surfactant paste 12 comprises from about 30% to about 95%, preferably from about 60% to about 95% and, most preferably from about 70% to about 75%, by weight of a detergent surfactant in paste form.
The surfactant paste 12 includes polyethylene glycol, having a melting point temperature of from 35 to 70°C, to facilitate production of high density detergent agglomerates with improved flow properties. It has been found that by including non-aqueous polyethylene glycol in the surfactant paste 12 which at least partially replaces the water in the paste surprisingly results in the formation of agglomerates having substantially improved flow properties. The non-aqueous binder in the paste not only improves the agglomerates ultimately formed by the instant process, but also retains the processability and transportability of the paste in that the viscosity remains low enough for such tasks. While not intending to be bound by theory, it is believed that partial replacement of the water in the paste by the non-aqueous binder renders agglomeration to occur at a higher temperature and to be more controllable resulting in the formation of more crisp, free flowing agglomerates.
Accordingly, the surfactant paste also comprises from about 0.1% to about 50%, more preferably from about 1% to about 15%, and most preferably from about 2% to about 8%, by weight of the the non-aqueous polyethylene glycol and the balance water, and optionally, other conventional detergent ingredients. The polyethylene glycol enhances agglomeration by providing a "binding" or "sticking" agent for the detergent components in the process. The polyethylene glycol preferably has a viscosity of from about 100 cps to about 100,000 cps, most preferably from about 1000 cps to about 25,000 cps. Also, it preferably has a melting point of from about 40°C to about 60 °C, so that it can operate most effectively in the instant process.
Preferably, the dry starting detergent material 14 comprises from about 20% to about 50%, preferably from about 25% to about 45% and, most preferably from about 30% to about 40% of an aluminosilicate or zeolite builder, and from about 10% to about 40%, preferably from about 15% to about 30% and, most preferably from about 15% to about 25% of a sodium carbonate. Most preferably, the builder is selected from the group consisting of aluminosilicates, crystalline layered silicates, sodium carbonate, Na₂Ca(CO₃)₂, K₂Ca(CO₃)₂, Na₂Ca₂(CO₃)₃, NaKCa(CO₃)₂, NaKCa₂(CO₃)₃, K₂Ca₂(CO₃)₃, and mixtures thereof. It should be understood that additional starting detergent ingredients several of which are described hereinafter may be mixed into high speed mixer/densifier 10 without departing from the scope of the invention.
Preferably, the ratio of the surfactant paste 12 to the dry starting detergent material 14 is from about 1:10 to about 10:1, more preferably from about 1:4 to about 4:1 and, most preferably from about 2:1 to about 2:3.
It has been found that the first processing step can be successfully completed, under the process parameters described herein, in a high speed mixer/densifier which preferably is a Lödige CB mixer or similar brand mixer. These types of mixers essentially consist of a horizontal, hollow static cylinder having a centrally mounted rotating shaft around which several plough-shaped blades are attached. The shaft rotates at a speed of from about 100 rpm to about 2500 rpm, more preferably from about 300 rpm to about 1600 rpm. Preferably, the mean residence time of the detergent ingredients in the high speed mixer/densifier 10 is preferably in range from about 2 seconds to about 45 seconds, and most preferably from about 5 seconds to about 15 seconds.
The resulting detergent agglomerates formed in the high speed mixer densifier are then fed into a lower or moderate speed mixer-densifier 16 during which further agglomeration and densification is carried forth. This particular moderate speed mixer densifier used in the present process should include liquid distribution and agglomeration tools so that both techniques can be carried forth simultaneously. It is preferable to have the moderate speed mixer/densifier 16 to be, for example, a Lödige KM (Ploughshare) mixer. Drais® K-T 160 mixer or similar brand mixer. The residence time in the moderate speed mixer densifier is preferably from about 0.5 minutes to about 15 minutes, most preferably the residence time is about 1 to about 10 minutes. The liquid distribution is accomplished by cutters, generally smaller in size than the rotating shaft, which preferably operate at about 3600 rpm.
In accordance with the present process, the high speed mixer/densifier and moderate speed mixer/densifier in combination impart a requisite amount of energy to form the desired agglomerates. The moderate speed mixer/densifier imparts from about 5 × 10¹⁰ erg/kg to about 2 × 10¹² erg/kg at a rate of from about 3 × 10⁸ erg/kg-sec to about 3 × 10⁹ erg/kg-sec to form free flowing high density detergent agglomerates. The energy input and rate of input can be determined by calculations from power readings to the moderate speed mixer/densifier with and without granules, residence time of the granules in the mixer/densifier, and the mass of the granules in the mixer/densifier. Such calculations are clearly within the scope of the skilled artisan.
The density of the resulting detergent agglomerates exiting the moderate speed mixer/densifier 16 is at least 650 g/l, more preferably from about 700 g/l to about 875 g/l. Thereafter, the detergent agglomerates are dried in a fluid bed dryer or similar apparatus to obtain the high density granular detergent composition which is ready for packaging and sale as a low dosage, compact detergent product at this point. The detergent agglomerates produced by the process preferably have a surfactant level of from about 25% to about 55%, more preferably from about 35% to about 55% and, most preferably from about 45% to about 55%. The particle porosity of the resulting detergent agglomerates of the composition is preferably in a range from about 5% to about 20%, more preferably at about 10%. As those skilled in the art will readily appreciate, a low porosity detergent agglomerate provides a dense or low dosage detergent product, to which the present process is primarily directed.
In addition, an attribute of dense or densified detergent agglomerates is the relative particle size. The present process typically provides agglomerates having a median particle size of from about 400 microns to about 700 microns, and more preferably from about 400 microns to about 500 microns. As used herein, the phrase "median particle size" refers to individual agglomerates and not individual particles or detergent granules. The combination of the above-referenced porosity and particle size results in agglomerates having density values of 650 g/l and higher Such a feature is especially useful in the production of low dosage laundry detergents as well as other grartular compositions such as dishwashing compositions.

Optional Process Steps

In an optional step of the present process, the detergent agglomerates exiting the fluid bed dryer are further conditioned by cooling the agglomerates in a fluid bed cooler or similar apparatus as are well known in the art. Another optional process step involves adding a coating agent to improve flowability and/or minimize over agglomeration of the detergent composition in one or more of the following locations of the instant process: (1) the coating agent can be added directly after the fluid bed cooler as shown by coating agent stream (preferred); (2) the coating agent may be added between the fluid bed dryer and the fluid bed cooler as shown by coating agent stream (3) the coating agent may be added between the fluid bed dryer and the moderate speed mixer/densifier as shown by stream and/or (4) the coating agent may be added directly to the moderate speed mixer/densifier and the fluid bed dryer as shown by stream. It should be understood that the coating agent can be added in any one or a combination of streams. The coating agent stream 22-is the most preferred in the instant process. The coating agent is preferably selected from the group consisting of aluminosilicates, silicates, carbonates and mixtures thereof. The coating agent not only enhances the free flowability of the resulting detergent composition which is desirable by consumers in that it permits easy scooping of detergent during use, but also serves to control agglomeration by preventing or minimizing over agglomeration, especially when added directly to the moderate speed mixer/densifier As those skilled in the art are well aware, over agglomeration can lead to very undesirable flow properties and aesthetics of the final detergent product.
Other optional steps contemplated by the present process include screening the oversized detergent agglomerates in a screening apparatus which can take a variety of forms including but not limited to conventional screens chosen for the desired particle size of the finished detergent product. Other optional steps include conditioning of the detergent agglomerates by subjecting the agglomerates to addinonal drying. Optionally, the process can comprises the step of spraying an additional binder in one or both of the mixer/densifiers. The binder can comprise the same non-aqueous binder materials used in the surfactant paste described previously.
Another optional step of the instant process entails finishing the resulting detergent agglomerates by a variety of processes including spraying and/or admixing other conventional detergent ingredients, collectively referenced as the finishing step. For example, the finishing step encompasses spraying perfumes, brighteners and enzymes onto the finished agglomerates to provide a more complete detergent composition. Such techniques and ingredients are well known in the art.

Detergent Surfactant Paste

As described briefly previously, the detergent surfactant paste used in the process is preferably in the form of a non-aqueous viscous paste. This so-called viscous surfactant paste has a viscosity of from about 5.000 cps to about 100.000 cps. more preferably from about 10.000 cps to about 80.000 cps. The viscosity is measured at 70°C and at shear rates of about 10 to 100 sec.^-1.
The surfactant itself, in the viscous surfactant paste, is preferably selected from anionic, nonionic, zwitterionic, ampholytic and cationic classes and compatible mixtures thereof. Detergent surfactants useful herein are described in U.S. Patent 3,664,961, Norris, issued May 23, 1972, and in U.S. Patent 3,919,678, Laughlin et al., issued December 30, 1975. Useful cationic surfactants also include those described in U.S. Patent 4.222,905, Cockrell, issued September 16, 1980, and in U.S. Patent 4,239,659, Murphy, issued December 16, 1980. Of the surfactants, anionics and nonionics are preferred and anionics are most preferred.
Nonlimiting examples of the preferred anionic surfactants useful in the surfactant paste include the conventional C₁₁-C₁₈ alkyl benzene sulfonates ("LAS"), primary, branched-chain and random C₁₀-C₂₀ alkyl sulfates ("AS"), the C₁₀-C₁₈ secondary (2,3) alkyl sulfates of the formula CH₃(CH₂)_x(CHOSO₃ ^-M⁺)CH₃ and CH₃(CH₂)_y(CHOSO₃ ^-M⁺)CH₂CH₃ where x and (y + 1) are integers of at least about 7, preferably at least about 9, and M is a water-solubilizing cation, especially sodium, unsaturated sulfates such as oleyl sulfate, and the C₁₀-C₁₈ alkyl alkoxy sulfates ("AE_xS"; especially EO 1-7 ethoxy sulfates).
Optionally, other exemplary surfactants useful in the paste of the invention include C₁₀-C₁₈ alkyl alkoxy carboxylates (especially the EO 1-5 ethoxycarboxylates), the C_10-18 glycerol ethers, the C₁₀-C₁₈ alkyl polyglycosides and their corresponding sulfated polyglycosides, and C₁₂-C₁₈ alpha-sulfonated fatty acid esters. If desired, the conventional nonionic and amphoteric surfactants such as the C₁₂-C₁₈ alkyl ethoxylates ("AE") including the so-called narrow peaked alkyl ethoxylates and C₆-C₁₂ alkyl phenol alkoxylates (especially ethoxylates and mixed ethoxy/propoxy), C₁₂-C₁₈ betaines and sulfobetaines ("sultaines"), C₁₀-C₁₈ amine oxides, and the like, can also be included in the overall compositions. The C₁₀-C₁₈ N-alkyl polyhydroxy fatty acid amides can also be used. Typical examples include the C₁₂-C₁₈ N-methylglucamides. See WO 9,246,154. Other sugar-derived surfactants include the N-alkoxy polyhydroxy fatty acid amides, such as C₁₀-C₁₈ N-(3-methoxypropyl) glucamide. The N-propyl through N-hexyl C₁₂-C₁₈ glucamides can be used for low sudsing. C₁₀-C₂₀ conventional soaps may also be used. If high sudsing is desired, the branched-chain C₁₀-C₁₆ soaps may be used. Mixtures of anionic and nonionic surfactants are especially useful. Other conventional useful surfactants are listed in standard texts.

Dry Detergent Material

The starting dry detergent material of the present process preferably comprises a detergent aluminosilicate builder which are referenced as aluminosilicate ion exchange materials and sodium carbonate. The aluminosilicate ion exchange materials used herein as a detergent builder preferably have both a high calcium ion exchange capacity and a high exchange rate. Without intending to be limited by theory, it is believed that such high calcium ion exchange rate and capacity are a function of several interrelated factors which derive from the method by which the aluminosilicate ion exchange material is produced. In that regard, the aluminosilicate ion exchange materials used herein are preferably produced in accordance with Corkill et al. U.S. Patent No. 4.605.509 (Procter & Gamble).
Preferably, the aluminosilicate ion exchange material is in "sodium" form since the potassium and hydrogen forms of the instant aluminosilicate do not exhibit the as high of an exchange rate and capacity as provided by the sodium form. Additionally, the aluminosilicate ion exchange material preferably is in over dried form so as to facilitate production of crisp detergent agglomerates as described herein. The aluminosilicate ion exchange materials used herein preferably have particle size diameters which optimize their effectiveness as detergent builders. The term "particle size diameter" as used herein represents the average particle size diameter of a given aluminosilicate ion exchange material as determined by conventional analytical techniques, such as microscopic determination and scanning electron microscope (SEM). The preferred particle size diameter of the aluminosilicate is from about 0.1 micron to about 10 microns, more preferably from about 0.5 microns to about 9 microns. Most preferably, the particle size diameter is from about 1 microns to about 8 microns.
Preferably, the aluminosilicate ion exchange material has the formula

Na_z[(AlO₂)_z.(SiO₂)_y]xH₂O

wherein z and y are integers of at least 6, the molar ratio of z to y is from about 1 to about 5 and x is from about 10 to about 264. More preferably, the aluminosilicate has the formula

Na₁₂[(AlO₂)₁₂.(SiO₂)₁₂]xH₂O

wherein x is from about 20 to about 30, preferably about 27. These preferred aluminosilicates are available commercially, for example under designations Zeolite A, Zeolite B and Zeolite X. Alternatively, naturally-occurring or synthetically derived aluminosilicate ion exchange materials suitable for use herein can be made as described in Krummel et al, U.S. Patent No. 3,985,669.
The aluminosilicates used herein are further characterized by their ion exchange capacity which is at least about 200 mg equivalent of CaCO₃ hardness/gram, calculated on an anhydrous basis, and which is preferably in a range from about 300 to 352 mg equivalent of CaCO₃ hardness/gram.
Preferably, there is present a water-soluble cation selected from the group consisting of hydrogen, water-soluble metals, hydrogen, boron, ammonium, silicon, and mixtures thereof, more preferably, sodium, potassium, hydrogen, lithium, ammonium and mixtures thereof, sodium and potassium being highly preferred. Nonlumiting examples of noncarbonate anions include those selected from the group consisting of chloride, sulfate, fluoride, oxygen, hydroxide, silicon dioxide, chromate, nitrate, borate and mixtures thereof. Preferred builders of this type in their simplest forms are selected from the group consisting of Na₂Ca(CO₃)₂, K₂Ca(CO₃)₂, Na₂Ca₂(CO₃)₃, NaKCa(CO₃)₂, NaKCa₂(CO₃)₃, K₂Ca₂(CO₃)₃, and combinations thereof. An especially preferred material for the builder described herein is Na₂Ca(CO₃)₂ in any of its crystalline modifications.
Suitable builders of the above-defined type are further illustrated by, and include, the natural or synthetic forms of any one or combinations of the following minerals: Afghanite, Andersonite, Ashcroftine Y, Beyerite, Borcarite, Burbankite. Butschliite, Cancrinite, Carbocernaite, Carletonite. Davyne, Donnayite Y, Fairchildite, Ferrisurite, Franzinite, Gaudefroyite, Gaylussite, Girvasite, Gregoryite, Jouravskite, Kamphaugite Y, Kettnerite, Khanneshite, LepersonniteGd, Liottite, MckelveyiteY, Microsommite, Mroseite, Natrofairchildite, Nyerereite, RemonditeCe, Sacrofanite, Schrockingerite, Shortite, Surite, Tunisite, Tuscanite, Tyrolite, Vishnevite, and Zemkorite, Preferred mineral forms include Nyererite, Fairchildite and Shortite.

Adjunct Detergent Ingredients

The starting dry detergent material in the present process can include additional detergent ingredients and/or, any number of additional ingredients can be incorporated in the detergent composition during subsequent steps of the present process. These adjunct ingredients include other detergency builders, bleaches, bleach activators, suds boosters or suds suppressers, anti-tamish and anticorrosion agents, soil suspending agents, soil release agents, germicides, pH adjusting agents, non-builder alkalinity sources, chelating agents, smectite clays, enzymes, enzyme-stabilizing agents and perfumes. See U.S. Patent 3,936,537, issued February 3, 1976 to Baskerville, Jr. et al.
Other builders can be generally selected from the various water-soluble, alkali metal, ammonium or substituted ammonium phosphates, polyphosphates, phosphonates, polyphosphonates, carbonates, borates, polyhydroxy sulfonates, polyacetates, carboxylates, and polycarboxylates. Preferred are the alkali metal, especially sodium, salts of the above. Preferred for use herein are the phosphates, carbonates, C_10-18 fatty acids, polycarboxylates, and mixtures thereof. More preferred are sodium tripolyphosphate, tetrasodium pyrophosphate, citrate, tartrate mono- and di-succinates, and mixtures thereof (see below).
In comparison with amorphous sodium silicates, crystalline layered sodium silicates exhibit a clearly increased calcium and magnesium ion exchange capacity. In addition, the layered sodium silicates prefer magnesium ions over calcium ions, a feature necessary to insure that substantially all of the "hardness" is removed from the wash water. These crystalline layered sodium silicates, however, are generally more expensive than amorphous silicates as well as other builders. Accordingly, in order to provide an economically feasible laundry detergent, the proportion of crystalline layered sodium silicates used must be determined judiciously.
The crystalline layered sodium silicates suitable for use herein preferably have the formula

NaMSi_xO_{2x+ 1}.yH₂O

wherein M is sodium or hydrogen, x is from about 1.9 to about 4 and y is from about 0 to about 20. More preferably, the crystalline layered sodium silicate has the formula

NaMSi₂O₅.yH₂O

wherein M is sodium or hydrogen, and y is from about 0 to about 20. These and other crystalline layered sodium silicates are discussed in Corkill et al, U.S. Patent No. 4,605,509.
Specific examples of inorganic phosphate builders are sodium and potassium tripolyphosphate, pyrophosphate, polymeric metaphosphate having a degree of polymerization of from about 6 to 21, and orthophosphates. Examples of polyphosphonate builders are the sodium and potassium salts of ethylene diphosphonic acid, the sodium and potassium salts of ethane 1-hydroxy-1, 1-diphosphonic acid and the sodium and potassium salts of ethane, 1,1,2-triphosphonic acid. Other phosphorus builder compounds are disclosed in U.S. Patents 3,159,581; 3,213,030; 3,422,021; 3,422,137; 3,400,176 and 3,400,148.
Examples of nonphosphorus, inorganic builders are tetraborate decahydrate and silicates having a weight ratio of SiO₂ to alkali metal oxide of from about 0.5 to about 4.0, preferably from about 1.0 to about 2.4. Water-soluble, nonphosphorus organic builders useful herein include the various alkali metal, ammonium and substituted ammonium polyacetates, carboxylates, polycarboxylates and polyhydroxy sulfonates. Examples of polyacetate and polycarboxylate builders are the sodium, potassium, lithium, ammonium and substituted ammonium salts of ethylene diamine tetraacetic acid, nitrilotriacetic acid, oxydisuccinic acid, mellitic acid, benzene polycarboxylic acids, and citric acid.
Polymeric polycarboxylate builders are set forth in U.S. Patent 3,308,067, Diehl, issued March 7, 1967. Such materials include the water-soluble salts of homo- and copolymers of aliphatic carboxylic acids such as maleic acid, itaconic acid, mesaconic acid, fumaric acid, aconitic acid, citraconic acid and methylene malonic acid. Some of these materials are useful as the water-soluble anionic polymer as hereinafter described, but only if in intimate admixture with the non-soap anionic surfactant.
Other suitable polycarboxylates for use herein are the polyacetal carboxylates described in U.S. Patent 4,144,226, issued March 13, 1979 to Crutchfield et al, and U.S. Patent 4,246,495. issued March 27, 1979 to Crutchfield et al. These polyacetal 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 detergent composition. Particularly preferred polycarboxylate builders are the ether carboxylate builder compositions comprising a combination of tartrate monosuccinate and tartrate disuccinate described in U.S. Patent 4,663,071, Bush et al., issued May 5. 1987.
Bleaching agents and activators are described in U.S. Patent 4,412,934, Chung et al., issued November 1, 1983, and in U.S. Patent 4,483,781, Hartman, issued November 20, 1984. Chelating agents are also described in U.S. Patent 4,663.071. Bush et al., from Column 17, line 54 through Column 18, line 68. Suds modifiers are also optional ingredients and are described in U.S. Patents 3,933,672, issued January 20, 1976 to Bartoletta et al., and 4,136,045, issued January 23, 1979 to Gault et al.
Suitable smectite clays for use herein are described in U.S. Patent 4,762,645, Tucker et al, issued August 9, 1988, Column 6, line 3 through Column 7, line 24. Suitable additional detergency builders for use herein are enumerated in the Baskerville patent, Column 13. line 54 through Column 16, line 16, and in U.S. Patent 4,663,071, Bush et al, issued May 5, 1987.
In order to make the present invention more readily understood, reference is made to the following examples, which are intended to be illustrative only and not intended to be limiting in scope.

EXAMPLE I

This Example illustrates the process of the invention which produces free flowing, crisp, high density detergent composition in the form of agglomerates. Two feed streams of various detergent starting ingredients are continuously fed, at a rate of 1270 kg/hr, into a Lödige CB-30 mixer/densifier, one of which comprises a surfactant paste containing surfactant and the non-aqueous binder, polyethylene glycol and the other stream containing starting dry detergent material containing aluminosilicate and sodium carbonate. The rotational speed of the shaft in the Lödige CB-30 mixer/densifier is about 1400 rpm and the mean residence time is about 10 seconds. The contents from the Lödige CB-30 mixer/densifer are continuously fed into a Lödige KM 600 mixer/densifer for further agglomeration during which the mean residence time is about 6 minutes The resulting detergent agglomerates are then fed to a fluid bed dryer and then to a fluid bed cooler, the mean residence time being about 10 minutes and 15 minutes, respectively. A coating agent, aluminosilicate, is fed about midway down the moderate speed mixer/densifier to control and prevent over agglomeration. The detergent agglomerates are then screened with conventional screening apparatus resulting in a uniform particle size distribution. The composition of the detergent agglomerates exiting the fluid bed cooler is set forth in Table I below:

TABLE I

Component	% Weight of Total Feed
C_14-15 alkyl sulfate	22.5
C_12.3 linear alkylbenzene sulfonate	2.5
Aluminosilicate	35.2
Sodium carbonate	21.0
Polyethylene glycol (MW 4000)	1.5
Misc. (water, etc.)	12.3
	100.0

Additional detergent ingredients including perfumes, enzymes, and other minors are sprayed onto the agglomerates described above in the finishing step to result in a finished detergent composition which is admixed with spray dried granules in a 60:40 weight ratio (agglomerates: spray dried granules). The relative proportions of the overall finished detergent composition produced by the process of instant process is presented in Table II below:

TABLE II

Component	(% weight)
C_14-15 alkyl sulfate/C_12.3 linear alkylbenzene sulfonate	16.3
Neodol 23-9.5¹	1.8
Polyacrylate (MW=4500)	3.2
Polyethylene glycol (MW=4000)	1.7
Sodium Sulfate	5.7
Aluminosilicate	26.3
Sodium carbonate	33.1
Protease enzyme	0.4
Amylase enzyme	0.1
Lipase enzyme	0.2
Cellulase enzyme	0.1
Minors (water, perfume, etc.)	11.1
	100.0

¹ C_12-13 alkyl ethoxylate (EO= 9) commercially available from Shell Oil Company.

The density of the resulting fully formulated detergent composition is 561 g/l, the median particle size is 450 microns. The density of the agglomerates alone is 810 g/l.

EXAMPLE II

This Example illustrates another process in accordance with the invention in which the steps described in Example I are performed except the coating agent, aluminosilicate, is added after the fluid bed cooler as opposed to in the moderate speed mixer/densifier. The composition of the detergent agglomerates exiting the fluid bed cooler after the coating agent is added is set forth in Table III below:

TABLE III

Component	% Weight of Total Feed
C_14-15 alkyl sulfate	22.7
C_12-13 linear alkylbenzene sulfonate	7.6
Aluminosilicate	34.5
Sodium carbonate	21.2
Polyethylene glycol (MW 4000)	1.5
Misc. (water, perfume, etc.)	12.5
	100.0

Additional detergent ingredients including perfumes, brighteners and enzymes are sprayed onto the agglomerates described above in the finishing step to result in a finished detergent composition which is admixed with spray dried granules in a 60:40 weight ratio (agglomerates: spray dried granules). The relative proportions of the overall finished detergent composition produced by the process of instant process is presented in Table IV below:

TABLE IV

The density of the resulting detergent composition is 560 g/l, the median particle size is 450 microns. The density of the agglomerates alone is 860 g/l.
Having thus described the invention in detail, it will be clear to those skilled in the art that various changes may be made without departing from the scope of the invention and the invention is not to be considered limited to what is described in the specification.

Claims

A process for continuously preparing high density detergent composition characterised by the steps of
(a) continuously mixing a detergent surfactant paste and dry starting detergent material into a high speed mixer/densifier having a shaft with a rotation speed of 100-2500 rpm to obtain detergent agglomerates, wherein said surfactant paste includes, by weight of said surfactant paste, from 30 to 95% by weight of detersive surfactant, 0.1 to 50% by weight polyethylene glycol having a melting point temperature of from 35 to 70°C and being introduced as non-aqueous polyethylene glycol, and the balance water,

(B) mixing said detergent agglomerates in a moderate speed mixer/densifier imparting from 5.10¹⁰erg/kg to 2.10¹²erg/kg at a rate of 3x10⁸erg/kg.sec to 3x10⁹erg/kg.sec to further densify and agglomerate said detergent agglomerates; and

(c) drying said detergent agglomerates so as to form said high density detergent composition.
A process according to claim 1 in which the surfactant paste includes from 60 to 95% by weight of detersive surfactant and 1 to 15% by weight of the polyethylene glycol.
A process according to any preceding claim in which the polyethylene glycol is polyethylene glycol 4000.
The process according to any preceding claim wherein said dry starting material is a builder selected from the group consisting of aluminosilicates, crystalline layered silicates, sodium carbonate, Na₂Ca(CO₃)₂, K₂Ca(CO₃)₂, Na₂Ca₂(CO₃)₃, NaKCa(CO₃)₂, NaKCa₂(CO₃)₃, K₂Ca₂(CO₃)₃, and mixtures thereof.
The process according to any preceding claim further characterised by the step of adding a coating agent after said moderate speed mixer/densifier, wherein said coating agent is selected from the group consisting of aluminosilicates, carbonates, silicates and mixtures thereof.
The process according to any preceding claim wherein the man residence time of said detergent agglomerates in said high speed mixer/densifier is in range from 2 seconds to 45 seconds.
The process according to any preceding claim wherein the mean residence time of said detergent agglomerates in said moderate speed mixer/densifier is in range from 0.5 minutes to 15 minutes.
A process for continuously preparing high density detergent composition characterised by the steps of
(a) continuously mixing a detergent surfactant paste and a dry starting detergent material characterised by a builder selected from the group consisting of aluminosilicates, crystalline layered silicates, sodium carbonate, Na₂Ca(CO₃)₂, K₂Ca(CO₃)₂, Na₂Ca₂(CO₃)₃, NaKCa(CO₃)₂, NaKCa₂(CO₃)₃, K₂Ca₂(CO₃)₃, and mixtures thereof, into a high speed mixer/densifier having a shaft with a rotation speed of 100-2500rpm to obtain detergent agglomerates, wherein said surfactant paste includes, by weight of said surfactant paste, from 70% to 95% of a detersive surfactant and 0.1 to 50% polyethylene glycol having a melting point temperature of from 35 to 70°C and being introduced as non-aqueous polyethylene glycol and the balance water, the weight ratio of said surfactant paste to said dry detergent material is from 1:10 to 10:1; mixing said detergent agglomerates in a moderate speed mixer/densifier imparting from 5 .10¹⁰erg/kg to 2 .10¹²erg/kg at a rate of 3x10⁸erg/kg.sec to 3x10⁹erg/kg.sec to further densify and agglomerate said detergent agglomerates,

(b) drying said detergent agglomerates; and

(c) adding a coating agent to obtain said high density detergent composition having a density of at least 650g/l.