PROCESSES FOR MAKING GRANULAR DETERGENT IN A FLUIDIZED BED GRANULATOR HAVING RECYCLING OF IMPROPERLY SIZED PARTICLES

Abstract: A process for the production of granular detergent compositions is provided wherein fluid bed granulation is employed in conjunction with selected recycle of oversized particles to control the uniformity of the resulting detergent composition. The process comprises feeding starting ingredients into a fluid bed granulator to at least partially granulate the feed material while employing the fluid bed to control undersized particle generation and sizing in conjunction with recycle to control oversized particles.

Description: PROCESSES FOR MAKING GRANULAR DETERGENT IN A FLUIDIZED BED GRANULATOR HAVING RECYCLING OF IMPROPERLY SIZED PARTICLES FIELD OF THE INVENTION The present invention relates to an improved process for making granular detergent compositions which have superior solubility, especially in cold temperature laundeπng solutions (1 e , less than about 30°C), excellent flow properties (even after storage), and aesthetics/appearance More particularly, the present process relates to the manufacture of detergent compositions via the use of a fluidized bed granulator having recycle of improperly sized particles BACKGROUND OF THE INVENTION Recently, there has been considerable interest withm the detergent industry for laundry detergents which have the convenience, aesthetics and solubility of liquid laundry detergent products, but retain the cleaning performance and cost of granular detergent products The problems, however, associated with past granular detergent compositions with regard to aesthetics, solubility, flowabihty after standard storage conditions and user convenience are formidable. Such problems have been exacerbated by the advent of "compact" or low dosage granular detergent products which typically do not dissolve in washing solutions as well as their liquid laundry detergent counterparts. These 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 pπor to use, but less convenient upon dispensing into the washing machine as compared to liquid laundry detergent which can be simply poured directly from the bottle as opposed to "scooped" from the box and then dispensed into the washing solution. As mentioned, such low dosage or "compact" detergent products unfortunately experience dissolution problems, especially in cold temperature laundeπng solutions (i.e , less than about 30°C). More specifically, poor dissolution results in the formation of "clumps" which appear as solid white masses remaining in the washing machine or on the laundered clothes after conventional washing cycles. These "clumps" are especially prevalent under cold temperature washing conditions and/or when the order of addition to the washing machine is laundry detergent first, clothes second and water last (commonly known as the "Reverse Order Of Addition" or "ROOA"). Such undesirable "clumps" are also formed if the consumer loads the washing machine in the order of clothes, detergent and then water Similarly, this clumping phenomenon can contribute to the incomplete dispensing of detergent m washing machines equipped with dispenser drawers or in other dispensing devices, such as a granulette. In this case, the undesired result is undissolved detergent residue in the dispensing device It has been found that the at least a portion of the dissolution profile of a granular detergent composition is impacted by the process used to manufacture that detergent. For instance, the dissolution profile of a detergent composition may be impacted by the uniformity of the particles in the composition with respect to both density and size of the particles This uniformity in turn is dictated m large part by the process by which the detergent is manufactured. However, to date manufacturing processes have been largely unsatisfactory in delivering compositions of the desired uniformity. Accordingly, the need remains for a process for the manufacture of detergent compositions which can provide compositions of the desired uniformity and as such exhibits improved solubility, is more aesthetically pleasing to consumers, has improved flowability and exhibits improved cleaning performance. SUMMARY OF THE INVENTION This need has been met by the present invention wherein a process for the manufacture of a detergent composition in a fluidized bed granulator with selected recycle of the improperly sized particles is provided. The present invention meets the aforementioned needs by controlling the size of the particles within the process to a greater extent than current detergent manufactuπng processes. Via the present invention the amount of undersized particles or fines present in a detergent composition are reduced via the use of fluidized bed granulation and the amount of oversized particles are also reduced via the screemg and re-mtroduction of these oversized particles to the process. The result is a detergent composition with improved solubility or dissolution in laundeπng solutions, especially in solutions kept at cold temperatures (i.e., less than about 30°C), is aesthetically pleasing to consumers and has improved flowability. In accordance with a first aspect of present invention, a process for making a granular detergent composition is provided. The process comprising the steps of: a) providing a granular feed stream; b) passing the granular feed stream into a fluidized bed granulator; c) at least partially agglomerating the feed stream in the fluidized bed granulator to form detergent agglomerates; d) screening the detergent agglomerates to separate oversized particles from properly sized particles; and e) re-mtroducmg o\ ersιzed particles to the process The process may comprise vaπous alternative scenaπos such as re-introduction to any combination of the fluid bed or. when present, to a premixer or finishing step The oversized particles may be optionally milled or ground before re-introduction to the process Undersized particles may be removed from the fluidized bed and re-introduced to the process such as to the premixer or fluidized bed or may be re -circulated within the fluid bed via the use of an internally recycling fluidized bed. Accordingly, it is an advantage of the invention to provide a process for making granular detergent compositions which exhibit improved solubility, are more aesthetically pleasing to consumers, have improved flowability and exhibit improved cleaning performance. It is a further advantage of the present invention to provide a process for making a granular detergent composition wherein selected recycle of improperly sized particles is employed to provide a more uniform detergent composition. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As used herein, the word "particles" means the entire size range of a detergent final product or component or the entire size range of discrete particles, agglomerates, or granules in a final detergent product or component admixture It specifically does not refer to a size fraction (i.e., representing less than 100% of the entire size range) of any of these types of particles unless the size fraction represents 100% of a discrete particle m an admixture of particles. For each type of particle component in an admixture, the entire size range of discrete particles of that type have the same or substantially similar composition regardless of whether the particles are in contact with other particles. For agglomerated components, the agglomerates themselves are considered as discrete particles and each discrete particle may be compπsed of a composite of smaller pπmary particles and binder compositions. As used herein, the phrase "geometric mean particle diameter" means the geometπc mass median diameter of a set of discrete particles as measured by any standard mass-based particle size measurement technique, preferably by dry sieving. As used herein, the phrase "geometπc standard deviation" or "span" of a particle size distπbution means the geometπc breadth of the best-fitted log-normal function to the above-mentioned particle size data which can be accomplished by the ratio of the diameter of the 84.13 percentile divided by the diameter of the 50 th percentile of the cumulative distribution (D 84 13 /D 50 ), See Gotoh et al, Powder Technology Handbook, pp. 6-1 1, Marcel Dekker 1997. As used herein, the phrase "builder" means any organic or inorganic material having "builder" performance in the detergency context, and specifically, organic or inorganic mateπal capable of removing water hardness from washing solutions and/or having dispersion or peptization properties As used herein, the term "bulk density" refers to the uncompressed, untapped powder bulk density, as measured by pouring an excess of powder sample through a funnel into a smooth metal vessel (e.g., a 500 ml volume cylinder), scraping off the excess from the heap above the πm of the vessel, measuring the remaining mass of powder and dividing the mass by the volume of the vessel. As used herein, "composition" and "granular detergent composition" are intended to include both final products and additives/components of a detergent composition. That is, the compositions produced by the processes claimed herein may be complete laundry detergent compositions or they may be additives that are used along with other detergent ingredients for laundeπng fabπcs and the like. The present invention is directed toward the use of selected recycle streams of improperly sized particles to advantageously produce a detergent that is more uniform in appearance and presents improved dissolution and aesthetic features as well. Via the use of a fluidized bed to control undersized particles and screening and remtroduction of oversized particles supeπor detergent compositions are produced. In general, the process of the present invention compπses the addition of a granular feed stream into a fluidized bed granulator to achieve at least partial granulation of the feed stream. Of course, one of ordinary skill in the art will recognize that multiple feed streams are possible within the scope of the present invention. The feed stream of the present invention may compπse granules of conventional detergent adjunct ingredients, wet detergent agglomerates, dry detergent agglomerates or spray-dπed detergent granules. Detergent adjunct ingredients includes but is not limited to, carbonates, phosphates, sulfates, zeolites or the like. Of course, other conventionally known ingredients may be included as well. Spray-dπed detergent granules include those particles which are manufactured via a conventional spray-drymg technique wherein a slurry of detergent mateπals is prepared and sprayed downward into a upwardly flowing stream of gas to dry the particles. A dry free flowing mateπal is produced from the process. Wet detergent agglomerates includes those particles that are manufactured via a granulation type process wherein detergent adjunct ingredients such as descnbed above are admixed with a liquid binder mateπal such as a surfactant or precursor thereof in a mixer or seπes of mixer to form granules of detergent mateπals. These particles are known as "wet agglomerates" until dπed and as dry agglomerates upon exiting a drying and optionally a conditioning stage. The conditioning stage may include sizing, grinding and cooling stages in any combination Granulation processes are well known in the detergent art. Some non-limiting examples include the process as descπbed in U S Patent Nos 5,489,392, 5,516,448 to Capeci et al the disclosures of which are herein incorporated by reference Accordingly, the present invention entails the introduction of both raw mateπal ingredients to form a detergent agglomerate or the introduction of previously formed detergent granules for continued processing of the granules. In a preferred embodiment of the present invention, the granular feed stream compπses at least two of the diffeπng types of granules such as spray-dπed granules and wet or dry detergent agglomerates In one highly preferred embodiment, the feed stream is comprised of spray-dπed detergent granules, dry detergent agglomerates and detergent adjunct ingredients. Optionally, the granular feed stream may be processed to remove particles having geometπc mean particle diameter of from about 500 microns to about 1500 microns with a geometπc standard deviation of from about 1 to about 2. These "m-spec" particles can be fed directly to the resulting granular detergent composition. The processing of the feed streams can be accomplished by, for example "screening", to remove the particles that have the desired geometπc mean particle diameter. By feeding these "m-spec" particles directly to the resulting granular detergent composition, the granular detergent making process is by-passed. This reduces the load on the granular detergent making equipment and increases the yield of particles within the desired size range. The fluidized bed granulator compπses a fluid bed dryer into which a detergent binder is added to agglomerate particles within the fluid bed. As stated earlier, the fluid bed of the present invention contπbutes to the overall uniformity of the detergent of the present invention via the granulation of the undersized particles. Undersized or "fine particles" are defined as particles that have a geometπc mean particle diameter that is less than about 1.65 standard deviations below the chosen geometπc mean particle diameter of the granular detergent composition at a given span or geometπc standard deviation. Oversized or large particles may also exist wherein "large particles" are defined as particles that have a geometπc mean particle diameter that is greater than about 1.65 standard deviations above the chosen geometπc mean particle diameter of the granular detergent composition at a given span or geometπc standard deviation. While not wishing to be bound by theory, it is believed that the undersized particles of the present invention are significantly reduced via the use of fluid bed granulation. Undersized particles are fluidized and circulated within the bed where they come into contact with the liquid binder mateπal sprayed into the fluid bed. As the undersized particles circulate withm the bed at a higher rate than other particles, these undersized particles come into contact with the binder mateπal at a higher rate Accordingly, the undersized particles are agglomerated or bound to other particles thereby reducing the total number of undersized particles. Via the use of fluidized bed granulation, the amount of undersized particles are reduced by as much as 10% more preferably 25% than conventional detergent processing techniques Undersized particles remaining after the fluid bed granulation step of the present invention may then be separated from the granular detergent during the process and re-introduced to the process The undersized particles may be extracted from the process via elutπation from the exhaust gases of the fluidized bed or via other conventional processing means such as an air lift or screen. These undersized particles may then be added to any unit operation m the process. These unit operation may include a premixer or seπes of premixers, fluid bed granulator, fluid bed coater, fluid bed or bulk heat exchanger for cooling, gπnder or milling equipment for oversize and screens used for sieving. In this manner, the process may be controlled for optimum reduction of undersized particles by selectively re-mtroducing the particles to various processing steps where they may be agglomerated to build size of the particles. Alternatively, undersized particles are controlled via the use of an internally recirculating fluidized bed wherein undersized particles are captured before exiting the fluidized bed and remain within the bed until agglomerated to acceptable sizes. Preferably, the fluid bed granulator of the present invention has multiple internal "stages" or "zones". A stage or zone is any discrete area within the fluid bed, and these terms are used interchangeably herein. The process conditions within a stage may be different or similar to the other stages m the fluid bed. It is understood that two adjacent fluid beds are equivalent to a single bed having multiple stages. The granular feed stream is at least partially agglomerated within the fluid bed via the addition of a liquid binder mateπal to the fluid bed. The granular feed stream or streams can be sized and split if desired and added at different stages, depending on, for example, the particle size and moisture level of the feed stream. Feeding different streams to different stages can minimize the load on the fluid bed, and optimize the particle size and shape as defined herein. Liquids are typically added to a bed through nozzles above or within the product flowing through the bed, and the nozzles can spray upward, across or downward depending on their position within the fluid bed. Manufacturers of such fluidized beds include Niro, Bepex, Spray Systems and Glatt. The liquid binder mateπal is added for purposes of enhancing granulation by providing a "binding" or "sticking" agent for the detergent components such as undersized particles. The binder is preferably selected from the group consisting of water, amonic surfactants and their precursors, nonionic surfactants, polyethylene gl col, polyvinyl pyrrohdone, polyacrylates, citπc acid and mixtures thereof Other suitable binder mateπals including those listed herein are described in Beerse et al, U S Patent No 5, 108.646 (Procter & Gamble Co.), the disclosure of which is incorporated herein by reference. Typical conditions within a fluidized bed granulator of the present invention include (I) from about 1 to about 20 minutes of mean residence time, (n) from about 100 to about 600 mm of depth of unfluidized bed, (m) a droplet spray size of less than 2 times the particles size, preferably not more than about 100, more preferably not more 50 micron, (IV) from about 150 to about 1600 mm of spray height from the fluid bed plate, (v) from about 0.1 to about 4.0 m/s of fluidizing velocity, preferably about 1 0 to about 3 0 m/s and (vi) from about 12 to about 200 °C of bed temperature, more preferably 15-100 °C Once again, one of ordinary skill in the art will recognize that the conditions in the fluid bed may vary depending on a number of factors. The fluid bed granulator of the present invention is preferably operated such that it has a flux number of from about 2.5 to about 4 5. Flux number (FN) is a ratio of the excess velocity (U e ) of the fluidization gas and the particle density (p p ) relative to the mass flux (q ]ιq ) of the liquid sprayed into the bed at a normalized distance (D 0 ) of the spraying device. The flux number provides an estimation of the operating parameters of a fluidized bed to control granulation within the bed. The flux number may be expressed either as the mass flux as determined by the following formula: FN m = log 1 o[ {PpU e }/q_ q ] or as the volume flux as determined by the formula. FN v = log,o[{U e }/q vlιq ] where q v g is the volume of spray into the fluid bed. Calculation of the flux number and a descπption of its usefulness is fully described m WO 98/58046 the disclosure of which is herein incorporated by reference. In addition, the fluid bed granulator of the present invention is preferably operated such that it has a Stokes number of less than one (1), more preferably from about 0.1 to about 0.5. The Stokes number is a measure of particle coalescence for descnbmg the degree of mixing or agglomerating occurπng to particles m a piece of equipment such as the fluid bed. The Stokes number is measured by the formula- Stokes number = 4pvd/9u wherein p is the apparent apparent particle density, v is the excess velocity, d is the mean particle diameter and u is the viscosity of the binder The Stokes number and a descπption of its usefullness is descπbed in detail in WO 99/03964, the disclosure of which is herein incorporated by reference. Optionally, the feed stream of present invention can be processed in at least one premixer before the addition of the feed stream to the fluidized bed granulator to form detergent premix. The pre -mixer may be one or a series of low, moderate or high speed mixers as is conventionally known in the art The particular mixer used m the present process should preferably include pulveπzmg or grinding and granulation tools although such tools are not required. To that end, it has been found that the preferred process of the present invention employs as a pre -mixer a Lodige KM™ (Ploughshare) moderate speed mixer, Lodige CB™ high speed mixer, or mixers made by Fukae, Drais, Schugi or similar brand mixer. The Lodige KM™ (Ploughshare) moderate speed mixer, which is a preferred mixer for use in the present invention, compπses a hoπzontal, hollow static cylinder having a centrally mounted rotating shaft around which several plough-shaped blades are attached. Preferably, the shaft rotates at a speed of from about 15 rpm to about 140 rpm, more preferably from about 80 rpm to about 120 rpm. The gπndmg or pulveπzmg is accomplished by cutters, generally smaller in size than the rotating shaft, which preferably operate at about 3600 rpm. Other mixers similar m nature which are suitable for use the process include the Lodige Ploughshare™ mixer and the Drais® K-T 160 mixer. Generally, m the process of the present invention, the shear will be no greater than the shear produced by a Lodige KM mixer with a tip speed of the ploughs below 30 m s or even below 10 m/s or even lower. The detergent agglomerates from the fluidized bed granulator may be further processed, if necessary to dry or cool the agglomerated particles. Preferably, the mean residence time of the vaπous detergent ingredients in the low, moderate or high speed mixer is preferably in range from about 0.1 seconds to about 30 minutes, most preferably the residence time is about 0.1 seconds to about 5 minutes. In this way, the density of the resulting detergent agglomerates is at the desired level. The processes of this invention may compπse the step of spraying an additional binder mateπal as hereinbefore descπbed in the pre-mixer or seπes of pre-rmxers in order to enhance granulation of the vaπous mateπals in the feed stream. In an optional embodiment of the present invention, the process may additionally include a finishing step including but not limited to, admix and/or spray-on of additional ingredients such as enzymes, bleach perfumes, etc or a packaging step Upon exiting from the fluid bed granulator (or any suitable stage therein), the detergent agglomerates may be sized to separate oversized particles from detergent agglomerates in the desired range The oversized particles may be sized according to conventionally known technology such as via screening. The oversized particles are then re-introduced into the process at appropnate locations in order to achieve the more uniform detergent composition as disclosed herein Via the control of oversized particles in conjunction with the undersized particles as descπbed hereinbefore, a detergent process for producing a supeπor performing detergent composition is controlled. As mentioned previously, the control of these oversized particles leads to better overall properties of the composition such as particle density and span as descπbed herein which contribute to the overall supeπoπty of the detergent composition. Preferably, but by no means required, the oversized particles may be optionally milled or ground before re-introduction to the process The milling or gπndmg may be preformed in conventional grinding equipment as is well known in the art of detergent processing. The oversized particles may be re-mtroduced to the process to any desired stage suitable for control of the process such as the fluid bed, the pre-mixer or seπes of pre-mixers or the finishing step, when present The oversized particle stream may be split and particles re-mtroduced into a combination of locations disclosed above. In preferred embodiments of the present invention, the oversized particles are passed through a gπnding step where the ground product is once again sized and acceptable particles passed through to a coating step as descπbed herein or to the resulting final detergent composition while the improperly sized particles are re-introduced to process as descπbed above. In preferred embodiments, the oversized particles are re-mtroduced into the pre-mixer or seπes of pre-mixers. In an optional embodiment, the feed stream may be sized as well before enteπng the fluid bed granulator. When an optional pre-mixer or seπes of pre-mixers is present, the sizing may occur before or after any or all of the pre-mixers. Thus, oversized particles may be removed at any stage of the process. These oversized particles may then be combined for re-introduction into the process, particularly after a preferred gnndmg or milling step . Of course, one of ordinary skill in the art will recognize that by re-introduction into a mixer of the present invention for both undersized and oversized particles, it is intended to include re-introduction to the feed streams enteπng the mixer or granulator in question as well re-introduction directly into the mixer or granulator The particles of this invention may be further processed in an optional step by adding a coating agent to improve the particle color, increase the particle "whiteness", or improve the particle flowability after the particles exit the mixer or the dryer to obtain the granular detergent composition produced by the present invention Coating agents herein may include dry inorganic materials such as zeolites, carbonates, sulfates etc Alternatively, the coating process may include the spray of a liquid coating agents such as aniomc surfactant, slurπes or solutions of inorganic or organic salts, and vaπous other matenals Those skilled in the art will appreciate that a wide variety of methods may be used to dry as well as cool the exiting detergent particles without departing from the scope of the invention Since the mixer can be operated at relatively low temperatures, the need for cooling apparatus is not required by the present process, which thereby further reduces manufacturing costs of the final product Another optional processing step includes continuously adding a coating agent such as zeolites and fumed silica to the mixer to facilitate free flowability of the resulting detergent particles and to prevent over granulation. The granular detergent composition achieves the desired benefits of solubility, improved aesthetics and flowability via the process of the present invention and the control or selection of the geometric mean particle diameter of certain levels of particles m the composition. By "improved aesthetics", it is meant that the consumer prefers a granular detergent product which has a more uniform appearance of particles as opposed to past granular detergent products which contained particles of varying size and composition. To that end, at least about 50%, more preferably at least about 75%, even more preferably at least about 90%, and most preferably at least about 95%, by weight of the total particles m the detergent product, have the selected mean particle size diameter. In this way, a substantial portion of the granular detergent product will have the uniform size so as to provide the aesthetic appearance desired by consumers. Preferably, the geometπc mean particle diameter of the particles is from about 500 microns to about 1500 microns, more preferably from about 600 microns to about 1200 microns, and most preferably from about 600 microns to about 1000 microns The particle size distπbution is defined by a relative tight geometπc standard deviation or "span" so as not to have too many particles outside of the target size. Accordingly, the geometπc standard deviation is preferably from about 1 to about 2, more preferably is from about 1.0 to about 1.7, even more preferably is from about 1.0 to about 1.4, and most preferably is from about 1.0 to about 1 2. The bulk density of the particles is preferably in the range of from about 400 g/L to about 850g/L. more preferably from about 550 g/1 to about 800 g/1 and even more preferably from about 600 g L to about 750 g L. As can be recognized by one of ordinary skill m the art, the control of lmproperly sized particles via the present invention contributes to the tight span of the composition produced by the present invention. While not intending to be bound by theory, it is believed that solubility and compositional quality are enhanced as a result of the particles in the detergent composition being more of the same size. Specifically, as a result of the particles being more uniform m size, the actual "contact points" among the particles in the detergent composition is reduced which, in turn, reduces the "bπdgmg effect" commonly associated with the "lump-gel" dissolution difficulties of granular detergent compositions Previous granular detergent compositions contained particles of varying sizes which leads to more contact points among the particles. For example, a large particle could have many smaller particles in contact with it rendeπng the particle site πpe for lump-gel formation The level and uniform size of the particles in the granular detergent composition of the present invention avoids such problems. By "a portion" of the particles, it is meant that at least some particles in the detergent composition contain a detersive surfactant and/or a detergent builder to provide the fundamental building blocks of a typical detergent composition. The vaπous surfactants and builders as well as their respective levels in the composition are set forth hereinafter. Typically, the detergent composition will contain from about 1% to about 50% by weight of a detersive surfactant and from about 1% to about 75% by weight of a detergent builder. A particularly important attπbute of detergent powders is color. Color is usually measured on a Hunter Coloπmeter and reported as three parameters "L", "a" and "b". Of particular relevance to the powdered detergent consumer is the whiteness of the powder determined by the equation L-3b. In general, whiteness values below about 60% are considered poor. Whiteness can be improved by a number of means known to those of ordinary skill in the art. For example, coating granules with Titanium Dioxide. Preferably the granular detergents of this invention have whitenesses of 60-100, preferably 75-100, more preferably, 85-100 and most preferably 92-100. Also preferred are granular detergents where all components have a whiteness difference (maximum - minimum) of less than about 40, preferably less than 30, more preferably less than 20 and most preferably less than 10. Another important attπbute of the granular detergent products of this invention is the shape of the individual particles. Shape can be measured in a number of different ways known to those of ordinary skill in the art. One such method is using optical microscopy with Optimus (V5.0) image analysis software. Important calculated parameters are: "Circulaπty" which is defined as (measured perimeter length of the particle image) " (measured area of the particle image) The circulaπty of a perfectly smooth sphere (minimum circularity) is 12 57; and "Aspect Ratio" which is defined as the length/width of the particle image Each of these attributes is important and can be averaged over the bulk granular detergent composition. And the combination of the two parameters as defined by the product of the parameters is important as well (i.e. both must be controlled to get a product with good appearance) Preferably, the granular detergent compositions produced by the process of the present invention have circularities less than about 50, preferably less than about 30, more preferably less than about 23, most preferably less than about 18. Also preferred are granular detergent compositions with aspect ratios less than about 2, preferably less than about 1.5, more preferably less than about 1.3 most preferably less than about 1.2. Additionally, it is preferred to have a uniform distπbution of shapes among the particles in the composition. Specifically, the granular detergent compositions of this invention have a standard deviation of the number distπbution of circulaπty less than about 20, that is preferably less than about 10, more preferably less than about 7 most preferably less than about 4. And the standard deviation of the number distπbution of aspect ratios is preferably less than about 1 , more preferably less than about 0.5, even more preferably less than about 0.3, most preferably less than about 0.2. In an especially preferred process of the present invention, granular detergent compositions are produced wherein the product of circulaπty and aspect ratio is less than about 100, preferably less than about 50, more preferably less than about 30, and most preferably less than about 20. Also preferred are granular detergent compositions with the standard deviation of the number distπbution of the product of circulaπty and aspect ratio of less than about 45, preferably less than about 20, more preferably less than about 7 most preferably less than about 2. Detergent Components The detergent composition of the present invention, preferably include surfactants such as anionic, nomonic, zwitteπonic, ampholytic and catiomc classes and compatible mixtures thereof. Detergent surfactants are descπbed m U.S. Patent 3,664,961, Norπs, issued May 23, 1972, and in U.S. Patent 3,919,678, Laughhn et al., issued December 30, 1975, both of which are incorporated herein by reference Catiomc surfactants include those descπbed m U.S. Patent 4,222,905, Cockrell, issued September 16, 1980, and in U.S. Patent 4,239,659, Murphy, issued December 16, 1980, both of which are also incorporated herein by reference. Nonhmiting examples of surfactant systems include the conventional Ci i -Ci g alkyl benzene sulfonates ("LAS") and primary, branched-chain and random C I Q- 20 alkyl sulfates ("AS"), the Ci fj -Ci g secondary (2,3) alkyl sulfates of the formula CH 3 (CH2) x (CHOS03 ~ M ~ ) CH 3 and CH 3 (CH 2 ) y (CHOS0 3 ~ M + ) CH 2 CH 3 where x and (y + 1) are integers of at least about 7, preferably at least about 9, and M is a water-solubihzmg cation, especially sodium, unsaturated sulfates such as oleyl sulfate, the CIQ-C ι . g alkyl alkoxy sulfates ("AE X S"; especially EO 1-7 ethoxy sulfates), CiQ-Ci g alkyl alkoxy carboxylates (especially the EO 1-5 ethoxycarboxylates), the Cιø-18 glycerol ethers, the Ci ø-Ci g alkyl polyglycosides and their corresponding sulfated polyglycosides, and C^-C j g alpha-sulfonated fatty acid esters If desired, the conventional nonionic and amphoteric surfactants such as the i alkyl ethoxylates ("AE") including the so-called narrow peaked alkyl ethoxylates and β-C 2 alkyl phenol alkoxylates (especially ethoxylates and mixed ethoxy/propoxy), C^-Cj g betames and sulfobetames ("sultatnes"), CJQ- I g amine oxides, and the like, can also be included in the surfactant system. The CiQ-Cj N-alkyl polyhydroxy fatty acid amides can also be used. Typical examples include the Ci 2-Cι N-methylglucamides. See WO 9,206,154. Other sugar-deπved surfactants include the N-alkoxy polyhydroxy fatty acid amides, such as C j ø- i N-(3-methoxypropyl) glucamide. The N-propyl through N-hexyl C^-Cj glucamides can be used for low sudsing. C\ 0- 20 conventional soaps may also be used. If high sudsing is desired, the branched-cham CI Q-CI 6 soaps may be used Mixtures of anionic and nonionic surfactants are especially useful. Other conventional useful surfactants are listed in standard texts. The detergent composition can, and preferably does, include a detergent builder. Builders are generally selected from the vanous water-soluble, alkali metal, ammonium or substituted ammonium phosphates, polyphosphates, phosphonates, polyphosphonates, carbonates, silicates, borates, polyhydroxy sulfonates, polyacetates, carboxylates, and polycarboxylates. Preferred are the alkah metal, especially sodium, salts of the above. Preferred for use herein are the phosphates, carbonates, silicates, C. „ . „ fatty acids, polycarboxylates, and mixtures thereof. More preferred are sodium tπpolyphosphate, tetrasodium pyrophosphate, citrate, tartrate mono- and di-succinates, sodium silicate, and mixtures thereof (see below). Specific examples of inorganic phosphate builders are sodium and potassium tπpolyphosphate, pyrophosphate, polymenc metaphosphate having a degree of polymeπzation 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 l-h\droxy-l, 1 -diphosphonic acid and the sodium and potassium salts of ethane, 1, 1,2-tπphosphonιc 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, all of which are incorporated herein by reference. Examples of nonphosphorus, inorganic builders are sodium and potassium carbonate, bicarbonate, sesquicarbonate, tetraborate decahydrate, and silicates having a weight ratio of SiO- 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 vaπous 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 diamme tetraacetic acid, nitπlotπacetic acid, oxydisuccimc acid, melhtic acid, benzene polycarboxyhc acids, and citπc acid. Polymeric polycarboxylate builders are set forth in U.S. Patent 3,308,067, Diehl, issued March 7, 1967, the disclosure of which is incorporated herein by reference. Such mateπals include the water-soluble salts of homo- and copolymers of aliphatic carboxyhc acids such as maleic acid, itaconic acid, mesacomc acid, fumaπc acid, acomtic acid, citraconic acid and methylenemalonic acid. Some of these mateπals are useful as the water-soluble anionic polymer as hereinafter descπbed, but only if in intimate admixture with the nonsoap anionic surfactant Other suitable polycarboxylates for use herein are the polyacetal carboxylates descπbed 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., both of which are incorporated herein by reference. These polyacetal carboxylates can be prepared by bπngmg together under polymeπzation conditions an ester of glyoxyhc acid and a polymeπzation initiator. The resulting polyacetal carboxylate ester is then attached to chemically stable end groups to stabilize the polyacetal carboxylate against rapid depolymeπzation in alkaline solution, converted to the corresponding salt, and added to a detergent composition. Particularly preferred polycarboxylate builders are the ether carboxylate builder compositions compπsmg a combination of tartrate monosuccinate and tartrate disuccinate descπbed in U.S. Patent 4,663,071, Bush et al., issued May 5, 1987, the disclosure of which is incorporated herein by reference. Water-soluble silicate solids represented by the formula SιO-»M-0, M being an alkali metal, and having a SιO--M-0 weight ratio of from about 0 5 to about 4.0, are useful salts in the detergent granules of the invention at levels of from about 2% to about 15% on an anhydrous weight basis, preferably from about 3% to about 8%. Anhydrous or hydrated particulate silicate can be utilized, as well. Any number of additional ingredients can also be included as components in the granular detergent composition. These include other detergency builders, bleaches, bleach activators, suds boosters or suds suppressors, anti-tarnish and anti-coπosion agents, soil suspending agents, soil release agents, germicides, pH adjusting agents, nonbuilder alkalinity sources, chelatmg agents, smectite clays, enzymes, enzyme-stabihzmg agents and perfumes. See U.S. Patent 3,936,537, issued February 3, 1976 to Baskerville, Jr. et al., incorporated herein by reference. Bleaching agents and activators are described m 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, both of which are incorporated herein by reference Chelatmg agents are also descπbed in U.S. Patent 4,663,071, Bush et al., from Column 17, line 54 through Column 18, line 68, incorporated herein by reference. Suds modifiers are also optional ingredients and are descπbed 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., both incorporated herein by reference. Suitable smectite clays for use herein are descπbed in U.S. Patent 4,762,645, Tucker et al., issued August 9, 1988, Column 6, line 3 through Column 7, line 24, incorporated herein by reference. 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, both incorporated herein by reference. EXAMPLES The following examples are presented for illustrative purposes only and are not to be construed as limiting the scope of the appended claims in any way. EXAMPLE I This example illustrates a process according to the present invention which produces uniform, free flowing detergent granules with good dissolution profiles. Two feed streams of spray dπed granules and dry agglomerates are continuously fed to a Lodige KM-600 moderate speed mixer at a rate of 600 Kg/hr at equal parts. 50 kg/hr of a solution of PEG 4000, 35 wt. % solids is added to the KM The resulting granules are fed into a fluid bed granulator, dryer, cooler with a gas fluidization velocity of approximately 1.5 m s 2 An additional 50 kg hr of PEG 4000, 35 wt % solids is sprayed in the fluid bed. The fluid bed is operated with a superficial velocity of 2.0 m/s 2 at the plate and a disengagement velocity of 1.4 m/s 2 . Approximately, 50 kg/hr of undersized matenal is ellutriated m the fluid bed, collected in a baghouse and re- mtroduced to the KM-600 pre-mixer. Following the fluid bed, the product is passed through a Morgensen screener set up to remove particle larger than 1200 microns. The oversized particles are then ground in a mill and returned to the fluid bed granulator. The resulting product has a geometπc mean particle diameter of 600 microns and a span of 1.4. Having thus descπbed the invention in detail, it will be obvious to those skilled m the art that vaπous changes may be made without departing from the scope of the invention and the invention is not to be considered limited to what is descπbed the specification.

Claims: WHAT IS CLAIMED IS 1 A process for making a granular detergent composition characterized by the steps of a) providing at least one granular feed stream, b) passing said granular feed stream into a fluidized bed granulator; c) at least partially agglomerating said feed stream in said fluidized bed granulator to form detergent agglomerates, d) sizing said detergent agglomerates to separate oversized particles from said detergent agglomerates, and e) re-mrroducmg said oversized particles to said process 2. A process for making a granular detergent composition characteπzed by the steps of: a) providing a granular feed stream characterized by at least at least two particles selected from the group consisting of spray dπed detergent granules, wet detergent agglomerates, dry detergent agglomerates and detergent adjunct ingredients; b) passing said granular feed stream into at least one pre-mixer to form a detergent premix; c) optionally screening said detergent premix to separate oversized particles; d) passing said detergent premix into a fluidized bed granulator; e) at least partially agglomerating said detergent premix in said fluidized bed granulator to form detergent agglomerates; f) sizing said detergent agglomerates to separate oversized particles from said detergent agglomerates; g) optionally passing said detergent agglomerates to a finishing step; and h) re-introducing said oversized particles to said process. 3. The process for making the granular detergent composition of any of Claims 1-2, further characteπzed by the step of milling said oversized particles before re-mtroduction into said process. 4. The process for making the granular detergent composition of any of Claims 1 -3, wherein said oversized particles are re-mtroduced into any unit operation m said process or into said fluid bed granulator. 5 The process as claimed in any of Claims 1-4 further characterized by the step of passing said granular feed stream through at least one pre-mixer before introduction into said fluid bed granulator and re-introducing at least a portion of said undersized particles to said at least one pre-mixer 6. The process as claimed in any of Claims 1-5 wherein said fluidized bed granulator is an internally re-circulating fluid bed and undersized particles are re-circulated internally withm the fluidized bed. 7. The process as claimed in any of Claims 1-6 further characteπzed by the step of screening said granular feed stream upon exiting said pre-mixer to separate oversized particles and re-mtroducing said oversized particles to the process. 8. The process as claimed in any of Claims 1-7 further characteπzed by the step of passing said granular feed stream through at least two pre-mixers, screening said feed stream upon exiting either or both of said pre-mixers to separate oversized particles and re- lntroducmg at least a portion of said oversized particles in either or both of said pre- mixers. 9. The process as claimed in any of Claims 1-8 wherein said fluidized bed granulator is operated at a flux number within the range of from 2.5 to 4.5. 10. The process as claimed in any of Claims 1-9 wherein said fluidized bed granulator is operated at a Stokes number of less than 1. 11. A process for producing a detergent composition characteπzed by forming detergent particles wherein at least 50%> by weight of said particles have a geometπc mean particle diameter of from about 500 microns to about 1500 microns with a geometπc standard deviation of from 1 to 2, wherein said particles are formed via at least partial granulation m a fluidized bed mixer/granulator wherein the amount of undersized particle is said process is controlled via the use of said fluid bed granulation and the amount of oversized particles is controlled via sizing and re-introduction to the process.

Inventors: BEIMESCH WAYNE EDWARD, CAPECI SCOTT WILLIAM, SPONTAK G GREGORY, WASSERMAN MATTHEW ISRAEL, WELCH ROBERT GARY, BEIMESCH, WAYNE, EDWARD, CAPECI, SCOTT, WILLIAM, SPONTAK, G., GREGORY, WASSERMAN, MATTHEW, ISRAEL, WELCH, ROBERT, GARY
Applicants: BEIMESCH WAYNE EDWARD, CAPECI SCOTT WILLIAM, PROCTER & GAMBLE, SPONTAK G GREGORY, WASSERMAN MATTHEW ISRAEL, WELCH ROBERT GARY, BEIMESCH, WAYNE, EDWARD, CAPECI, SCOTT, WILLIAM, SPONTAK, G., GREGORY, THE PROCTER & GAMBLE COMPANY, WASSERMAN, MATTHEW, ISRAEL, WELCH, ROBERT, GARY
Application year: 2000
Main classification: C11D11
IPC codes: C11D11, C11D17