Background of the Invention Disintegrant granules for disintegrating detergent tablets are conventionally prepared by mixing a cellulose or a cellulose woodpulp, blending with a disintegrant, optional salt, and optional humectant, and then compacting. The resulting compact is then granulated. Solid detergent tablets can be prepared by mixing the compacted cellulose granulate with the active ingredients plus any ancillary ingredients. The mixture can then be compressed by any convenient means into tablets, pellets, beads, balls, bars, disks, and briquettes.

Tablets for laundry and automatic dish washer applications are a convenient way to accurately deliver the correct amount of detergent during the wash cycle. Such accurate delivery is desirable to enable the consumer to realize maximum cost-effective performance from detergents and to prevent unnecessary detergent from being introduced into municipal waste water plants.

Conventional ultra laundry detergent powders and some automatic dishwashing formulations can often be tableted on conventional rotary and single-station tablet presses at high compression forces. Although detergent tablets compressed at high pressures resist breakage and often exhibit an elegant physical appearance, such tablets provide unacceptably

slow disintegration in the wash water. Tablets that have not disintegrated completely have not delivered the correct dose of detergent and consequently provide poor cleaning performance. Additionally, undisintegrated detergent tablets may cause residues on clothing, dishes, or in detergent dispensers.

One way to improve disintegration rates is to reduce compression force during tableting. However, this tends to result in weak tablets that may break easily during shipment and handling by the end user. Often, such weak tablets still do not exhibit the disintegration performance needed to eliminate all residues of undissolved detergent.

Disintegrants can be used to produce tablets with acceptable disintegration performance, yet provide tablets with adequate hardness.

The use of disintegrants, which function by either wicking water into the interior of the tablet, swelling by uptake of water, or by a combination of the two mechanisms, is well known in the pharmaceutical industry for the production of pharmaceutical tablets. Although traditional pharmaceutical disintegrants can provide some performance advantages for detergent tablets, the average particle size of ingredients normally used in pharmaceutical tablets is generally much smaller than the particle size of the granular detergent matrix. Therefore, pharmaceutical-grade disintegrants that perform primarily by swelling cannot develop sufficient force within the tablet to disrupt and weaken the tablet matrix.

Summary of the Invention We have found that pulps containing less than 10 wt% lignin do not alone exhibit significant disintegrating properties in granular form and cannot be considered disintegrants. Furthermore, we have found that excellent disintegrating granules are obtained when certain cross-linked disintegrants are granulated with such pulps at very low concentrations, and that compressed detergent tablets made therefrom rapidly disintegrate when placed in agitated aqueous media.

This invention provides a swellable compacted disintegrant granule for detergent tablets or other compressed, shaped solid detergent bodies.

The granule comprises a cellulose component and a disintegrant component, in which: (a) the cellulose component comprises particles of a pulp having a lignin content below about 10 wt%, an average particle size of about 30 microns to about 100 microns, and a span of 2 to 3; (b) the disintegrant component comprises particles of a material selected from the group consisting of cross-linked carboxymethyl cellulose, cross-linked polyvinylpyrrolidone, cross-linked polyacrylates, and mixtures thereof, the particles having a median particle size of about 40 microns to about 160 microns, with the largest particles no greater than 700 microns and the smallest particles no smaller than 1 micron; and (c) the disintegrant component comprise about 1 wt% to about 10 wt% of the granule, based on the total weight of disintegrant component and the cellulose component in the granule, and the cellulose component comprises about 90 wt% to about 99 wt% of the granule, based on the total weight of disintegrant component and the cellulose component in the granule.

In another aspect of the invention, the cellulose component is microcrystalline cellulose.

In yet another aspect, this invention is a shaped detergent body, including but not limited to, a compressed detergent tablet comprising the disintegrant granules compacted with detergent granules.

Detailed Description of the Invention In one aspect of this invention, disintegrant granules are prepared by mixing a cellulose component, a disintegrant component, optional salt, and optional humectant, and then compacting. The resulting compact is then granulated to form the disintegrant granules. Solid detergent bodies or tablets can be prepared by mixing the disintegrant granules with detergent granules. The resulting mixture can then be compressed by any convenient means into tablets, pellets, beads, balls, bars, disks, and briquettes.

Softwood and hardwood pulps, particularly sulfite and Kraft wood pulps, preferably those made from soft woods such as beech, fir, spruce and. pine or hard woods such as alder, aspen, and oak have been found to work well as cellulose component in this invention. Blends of softwood and hardwood pulps can also be used. In the sulfite process, wood chips are reduced under steam pressure to pulp with an acid chemical (calcium, magnesium, sodium, or ammonium bisulfite plus sulfurous acid). In the Kraft process, wood chips are reduced under steam pressure to pulp with alkaline chemicals (such as sodium hydroxide and sodium sulfide).

Pulps suitable for use in this invention are those that are refined to have a lignin content below about 10 wt%, preferably below about 5 wt% and more preferably below about 3 wt%. As is well known, low lignin pulps are typically produced by bleaching with, for example, chlorine dioxide, hydrogen peroxide, ozone, etc.

The wood pulp may be ground by any suitable means including air jet milling, cutting, ball milling or hammer milling. The preferred median fiber length (particle size) is 30 to 100 microns, preferably 30 to 75 microns, more preferably 50 to 60 microns, with a span of not more than 3.0, preferably as low as or slightly lower than 2.0.

Span is defined by the following formula : Span = (D10-Dgo)/Dso, in which Djo is defined as the diameter of particles at a point on a particle size distribution curve at which 10 % of the particles have a diameter larger than the value for Dio, Dso is defined as the diameter of particles at a point on a particle size distribution curve at which 90% of the particles have a diameter larger than the value for Dgo, and D50 is defined as the median particle size of the particle size distribution curve.

If there are too many large fibers, the resulting compacted blend will be weakly bonded, appear paper-like, and not break cleanly during granulation. If there are too many fines, the bulk density of the feed powder to the compression train will be too low, resulting in a low bulk density, dusty product.

Microcrystalline cellulose, which is partially depolymerized cellulose prepared by treating alpha cellulose with mineral acids, may also be used

as the cellulose component. Microcrystalline cellulose may be obtained from a raw material such as wood, wood pulps such as bleached sulfate and sulfate pulps, cotton, flax, hemp, bast or leaf fibers, regenerated forms of cellulose, soy hulls, corn hulls, nut hulls, and the like. It is generally prepared from the raw material sources by a combination of a chemical degradation and mechanical attrition. Chemical degradation may be accomplished by any of several well-known methods. For example, the raw material may be rendered into a cellulose rich pulp, and the pulp hydrolyzed with dilute mineral acid. Microcrystalline cellulose typically has a lignin content of essentially zero. Microcrystalline cellulose particles are typically from about 20 microns to about 250 microns in size and preferably have a span of 1.2 to 3.

The disintegrant component is a material capable of swelling, and/or wicking water into a tablet, which, preferably, also has a fibrous nature in order to wick water efficiently into the interior of the granule.

Particularly preferred as disintegrants are cross-linked materials including cross-linked carboxymethylcellulose (also known generically as croscarmellose sodium), cross-linked polyvinylpyrrolidone (also known as crospovidone), and cross-linked polyacrylates. Mixtures of two or more of these material may also be used as the disintegrant component.

Croscarmellose sodium is available as from the FMC Corporation, Philadelphia, PA. These materials are discussed in the Handbook of Pharmaceutical Excipients, 2d ed., American Pharmaceutical Association, pp. 141etseq, (1994).

The median particle size of the disintegrant particles is about 40 to about 160 microns, preferably 40 to 120 microns, with the largest particles being preferably no greater than 700 microns, and the smallest particles being preferably no smaller than 1 micron in particle size. The disintegrant component is present in the granule at a concentration in the range of about 0.5 wt% to about 10 wt%, preferably between 0.5 wt% to 5%, and more preferably between 0.5 wt% to 2.5 wt% based on the weight of the granule.

Certain salts may also be included in either the disintegrant granules or in the detergent granules. Sodium salts are especially preferred for laundry and automatic dish detergent applications, since the

salt does not add any hardness ions to the wash liquor and cleaning performance is maintained. Examples of salts suitable for use in the invention include sodium chloride, sodium sulfate (anhydrous), sodium bicarbonate and sodium carbonate. Such salts may optionally be used in the disintegrant granules, suitably at a concentration in the range of from about 1 wt% to about 4 wt%.

Humectants are desirable to prevent the disintegrant granule from forming irreversible hydrogen bonds and to facilitate a slight swelling of the disintegrant in the interior of the granule. Humectants that may be used include urea, polyethylene glycol of molecular weight greater than 800, and polyoxyl 40 stearate. If such humectants are used, the amounts of cellulose and disintegrant components in the disintegrant granules may be proportionately reduced; provided, however, that the concentration of the disintegrant component should not be reduced below about 0.5 wt% of the total disintegrant granule. If desired, such humectants may be used in the disintegrant granules at a concentration of from about 1 wt% to about 15 wt%.

The cellulose component is blended with the disintegrant component, and if present, the other ingredients.. Blending may be accomplished by any suitable means including ribbon blenders, cone blenders, or PK-type blenders equipped with an intensifier bar. The blended mixture is then compacted, with, for example, a roller compactor, i. e. the Bepex Pharmapaktor or Fitzpatrick Chilsonator. A Carver press also can be used to make hard compacts. Tablet presses, either single- station or rotary, can also be used. The compacts are then granulated using either an oscillating granular or other low-intensity mill.

The disintegrant granule particle size should be about 180 microns to 3000 microns, preferably about 315 microns to 2000 microns. If the particles are too fine, the disintegrant granules will be too small to yield a sufficiently large swelling force to fracture the tablet. If the granules are too large, there will be too few particles for a given loading in the tablet for the granules to form an interconnected network of fractures upon swelling.

Detergent compositions typically comprise one or more surfactants, one or more builders, and, optionally, other ingredients that are conventional components of detergent compositions, such as perfumes,

dyes, bleaches, enzymes, suds suppressers, soil suspension and anti- redeposition agents, and corrosion inhibitors. Detergent compositions are well known and are disclosed in numerous patents and publications, for example, Diehl, U. S. Pat. No. 3,308,067; Laughlin, U. S. Pat. No. 3,929,678; Crutchfield, U. S. Pat. Nos. 4,144,226 and 4,246,495; Vander Meer, U. S. Pat.

No. 4,597,898; Gosselink, U. S. Pat. No. 4,702,857; Panandiker, U. S. Pat.

No. 6,156,722; Baillely, U. S. Pat. No. 6,127,329; Hall, U. S. Pat. No.

6,096,703; Van Dijk, U. S. Pat. No. 6,087,311; and Warick, U. S. Pat. No.

6,083,895.

Builders assist in the control of mineral hardness. Conventional detergent builders include sequestrant builders, precipitant builders, and ion exchange builders. Detergent builders are discussed in Vander Meer, U. S. Pat. No. 4,597,898, especially column 17, line 1, to column 19, line 30.

Inorganic phosphate builders include water soluble, alkali metal, ammonium, and substituted ammonium phosphates, polyphosphates, pyro- phosphates, orthophosphates, phosphonates, and polyphosphonates.

Examples of water-soluble phosphate builders are the alkali metal triply- phosphates, such as sodium tripolyphosphate (STPP); sodium, potassium and ammonium pyrophosphate; sodium and potassium orthophosphate; sodium orthophosphate; sodium hexametaphosphate; sodium polymetaphosphates and mixtures of sodium polymetaphosphates, in which the degree of polymerization ranges from about 6 to 21.

Alkali metal carbonates, especially sodium carbonate, are used as precipitant builders. Sodium carbonate is typically either used in its anhydrous form or converted to its anhydrous form during detergent manufacture.

Water soluble alkali metal silicates may be used as builders in detergent compositions. Suitable alkali metal silicates have a mole ratio of Si02 to alkali metal oxide (M20) in the range of 0.5: 1 to 1: 4. Sodium silicate solids with a Si02 : Na2O ratio of about 1: 1.5 to 1: 3.5, are typically used in granular laundry detergent compositions.

Other useful builders include monomeric or oligomeric polycarboxylate cheating agents, polyhydroxysulfonates, and mixtures of these materials with their alkali metal, ammonium, and substituted

ammonium salts, e. g. citric acid or citrate/citric acid. Typical polycarboxylic acids are polyacrylic acid, oxydisuccinic acid, tartrate disuccinate, mellitic acid, carboxymethyloxysuccinate, etc. Nitrogen containing polycarboxylic acids include nitrilotriacetic acid and ethylene diamine tetraacetic acid and their alkali metal, ammonium, and substituted ammonium salts.

Polyhydroxsulfonates include compounds such as phloroglucinol trisulfonate.

Polycarboxylates containing four carboxy groups include oxydisuccinates, 1,1,2,2-ethane tetracarboxylates, 1,1,3,3-propane tetracarboxylates and 1,1,2,3-propane tetracarboxylates. Polycarboxylates containing sulfo substituents include the sulfosuccinate derivatives may also be used.

Polycarboxylates hydroxycarboxylates containing up to three carboxy groups per molecule, especially citric acid and citrates, are well known ingredients in detergent compositions. Other suitable sequestrant builders are the polyacetal carboxylates disclosed in Crutchfield, U. S. Pat. Nos.

4,144,226 and 4,246,495, and the homo-and co-polymers of aliphatic carboxylic acids such as maleic acid, itaconic acid, fumaric acid, etc., disclosed in Diehl, U. S. Pat. No. 3,308,067.

Borate builders, as well as builders containing borate-forming materials that can produce borate under detergent storage or wash conditions, are also use water-soluble builders.

The detergent composition may contain an ion exchange builder.

Useful ion exchange builders include both natural and synthetic crystalline and amorphous aluminosilicates, or zeolites, and mixtures thereof. Suitable crystalline aluminosilicate have the formula : Na, [ (AI02), (SiO2) yl. xH20 where z and y are at least about 6, the ratio of z to y is about 0.5 to 1.0; and x is from about 10 to about 264. Suitable amorphous aluminosilicates include Zeolite A, Zeolite P, Zeolite X, and Na12 [(Alo2) 12 (sio2) 12] xH2o where x is about 20 to about 30, especially about 27.

The aluminosilicate material are in hydrated form and are preferably crystalline, containing from 10% to 28%, more preferably from 18% to 22% water in bound form.

Detergent compositions comprise a surfactant or a mixture of surfactants. The surfactant or surfactants can be nonionic, semi-polar, anionic, ampholytic, zwitterionic, cationic, or a mixture thereof. Surfactants are typically include hydrophilic and hydrophobic groups. The hydrophobic group typically contains an organic moiety of 10 to 20 carbon atoms. The hydrophilic group typically contains a polyoxyethylene chain and/or an ionic group.

Numerous surfactants useful in detergent compositions are well known.

Surfactants are discussed in McCutcheon's Detergents and Emulsifiers, Manufacturing Confectioners Publishing Company, Glen Rock, NJ, and in Encyclopedia of Surfactants, Volumes 1-111, Compiled by M. and 1. Ash, Chemical Publishing Co., NY. Surfactants useful in detergent compositions are disclosed in Gosselink, U. S. Pat. No. 4,702,857, especially column 17, line 27, to column 22, line 19, and Laughlin, U. S. Pat. No. 3,929,678, especially column 5, line 65, to column 36, line 30.

Alkoxylated nonionic surfactants are typically produced by the condensation of an alkylen oxide group, typically ethylene oxide, with an organic hydrophobic group, typically a long chain aliphatic alcohol or alkyl phenol. The length of the hydrophilic polyoxyalkylene chain and the size of the hydrophobic group can be adjusted to produce the desired balance of hydrophilic and hydrophobic elements.

Ethoxylated alkyl phenols include the condensation product of alkyl phenols having an alkyl group containing about 6 to about 12 carbon atoms with about 5 to about 25 moles of ethylene oxide per mole of alkyl phenol.

The alkyl group may be straight chain or branched, such as octyl, 1,1,3,3- tetramethylbutyl, dodecyl, etc. Typical ethoxylated alkyl phenols are: nonyl phenol condensed about 9.5 moles of ethylene oxide, dodecylphenol condensed with about 12 moles of ethylene oxide, di-iso-octylphenol condensed with about 15 moles of ethylene oxide, etc.

Ethoxylated aliphatic alcohols include the condensation product of aliphatic alcohols with about 1 to about 25 moles of ethylene oxide per mole of alkyl alcohol. The alkyl alcohol may be straight chain or branched, primary or secondary, and generally contains about 8 to about 22 carbon atoms. Typical ethoxylated aliphatic alcohols are: myristyl alcohol condensed with 10 moles of ethylene oxide, coconut oil (a mixture of alcohols with alkyl groups varying form 10 to 14 carbon atoms) with about 9 moles of ethylene oxide, etc.

Ethylene oxide/propylene oxide block copolymers include the condensation products of ethylene oxide with a hydrophobic base formed by the condensation of propylene oxide with propylene oxide. Examples of these surfactants are the Pluronic0 surfactants. The condensation products of ethylene oxide with the product resulting from the reaction of propylene oxide and ethylenediamine may also be used.

Alkylpolysaccharides having a hydrophobic group containing from about 6 to about 30 carbon atoms, preferably form about 10 to about 16 carbon atoms, and a polysaccharide, such as a polyglycoside, containing hydrophilic group containing from about 1.5 to about 10, preferably from about 1.5 to about 3, saccharide units can be used. A polyalkylene oxide chain, such as polyoxyethylene chain, can be used to join the hydrophilic and hydrophobic moieties.

Semi-polar nonionic detergents include : water soluble amine oxides containing one alkyl group of from about 10 to 18 carbon atoms and two alkyl groups selected from the group consisting of alkyl groups and hydroxyalkyl groups containing 1 to 3 carbon atoms; water soluble phosphine oxides containing one alkyl group of from about 10 to 18 carbon atoms and two alkyl groups selected from the group consisting of alkyl groups and hydroxyalkyl groups containing 1 to 3 carbon atoms; and water soluble sulfoxides containing one alkyl group of from about 10 to 18 carbon atoms and one alkyl groups selected from the group consisting of alkyl groups and hydroxyalkyl groups containing 1 to 3 carbon atoms. Typical semi-polar surfactants are Cio-Cis alkyl dimethyl amine oxides and 2-(C8-C12 alkoxy) ethyl di-(2-hydroxy- ethyl) amine oxides.

Ampholytic surfactants are typically derivatives of secondary or tertiary amines in which one of the aliphatic groups contains about 8 to about 18 carbon atoms and at least one anionic water-solubilizing group, such as carboxylate, sulfate, sulfonate, phosphate, etc.

Anionic detergents include soaps, such as the sodium, potassium, ammonium and substituted ammonium salts of fatty acids containing from about 8 to about 24 carbon atoms, preferably about 10 to about 20 carbon atoms.

Synthetic anionic surfactants are salts, especially water soluble sodium, potassium, ammonium and substituted ammonium salts, in which the

surfactant portion is negatively charged. These surfactants include : (1) alkyl benzene sulfonates in which the alkyl group contains about 9 to about 15 carbon atoms; (2) alkyl sulfonates in which the alkyl group contains about 10 to 20 carbon atoms, especially linear alkylbenzene sulfonates in which the alkyl group contains, on the average, 11 to 13 carbon atoms; (3) sulfates of alkyl alcohols in which the alkyl group contains about 8 to 18 carbon atoms; (4) sulfates of ethoxylated alkyl alcohols in which the alkyl group contains about 10 to about 22, preferably about 12 to about 18, carbon atoms, and the polyoxyethylene chain contains about 1 to about 15, preferably about 1 to about 3, moles of ethylene oxide per molecule ; (5) sulfates of ethoxylated alkyl phenols in which the alkyl group contains about 8 to about 10 and the polyoxyethylene chain contains about 10 moles of ethylene oxide per molecule ; (6) phosphates of alkyl alcohols, ethoxylated alkyl alcohols, and ethoxylated alkyl phenols ; (7) alkyl glyceryl ether sulfonates and sulfates ; etc.

Cationic surfactants are salts, especially chloride, bromide, and methylsulfate quaternary ammonium salts, in which the surfactant portion is positively charged. Typical quaternary ammonium surfactants that can be used to advantage in the detergent compositions of this invention are: Cs-Cie alkyl trimethylammonium salts, C8-C16 alkyl di (hydroxyethyl) methyl ammonium salts, C8-C16 alkyl hydroxyethyldimethyl ammonium salts, and C8-C16 alkyl- oxypropyl trimethylammonium salts. Decyl trimethylammonium methylsulfate, lauryl trimethylammonium chloride, myristyl trimethylammonium bromide, and coconut trimethylammonium chloride and methyl sulfate are preferred.

Zwitterionic surfactants contain both a positive and a negative charge.

Typically they contain both a positively charged ammonium, sulfonium, or phosphonium group and a negatively charged sulfate, sulfonate, phosphate, or carboxylate group as well as a long chain organic and/or polyoxyethylene chain. Typical zwitterionic surfactants are: 3- (N, N-dimethyl-N-hexadecyl- ammino)-2-hydroxypropane-1-sulfonate,4- (N, N-dimethyl-N-tetradecyl- ammino) butane-1-sulfonate, 3-(N-4-n-dodecylbenzyl-N, N-dimethylammino)- propane-1-sulfonate,3-(N, N-dimethyl-N-alkylammino)-2-hydroxypropane-1- sulfonate in which the alkyl group averages 14.8 carbons in length, as well as the zwitterionic surfactants described in Laughlin, U. S. Pat. No. 3,929,678.

Other conventional ingredients may be included provided the ingredient is compatible with the other ingredients of the detergent

composition and the disintegrant composition, and the presence of these ingredients does not adversely affect the properties of the detergent composition or the disintegrant composition. Each added ingredient is used to modify the detergent composition in conventional form and in the amount required to achieve the desired effect without adversely affecting the properties of the composition.

To improve the cleaning power of the detergent composition an anti- redeposition agents may be added. Typical anti-redeposition agents include: polyvinyl pyrrolidone, hydroxyethyl cellulose, sodium carboxymethyl cellulose, polyacrylamide, and hydroxypropyl ethyl cellulose.

Filler salts may also be added. Sodium sulfate and sodium chloride are preferred, but other water soluble alkali metal sulfates, chlorides, nitrates, acetates, etc., may also be used. Other conventional ingredients include : bleaching agents, such as sodium perborate monohydrate, sodium perborate tetrahydrate, and sodium percarbonate; bleach activators, such as triacety cyanurate and sodium p-acetoxybenzene sulfonate ; corrosion inhibitors; anti- oxidants, such as 2,6-di-t-butyl4-methylphenol (BHT); dyes and other colorants; fillers ; caking inhibitions, such as p-toluene sulfonates, sulfosuccinates, talc, and calcium silicate ; optical brighteners; germicides, such as phenolic compounds and their alkali metal salts having antimicrobial activity, for example, o-phenylphenol and p-t-amylphenol ; pH adjusting agents, such as ethanolamine, triethanolamine, and sodium hydroxide; proteolytic and amylolytic enzymes; enzyme stabilizing agents; perfumes; fabric softening compositions; static control agents; optical opacifiers, such as polystyrene; suds regulants, such as dimethylpolysiloxane ; and the like. The use of these materials is well known.

The amount of each ingredient present in the detergent composition depends on the particular ingredients chosen and the effects desired. The builder can comprise up to about 60% by weight of the detergent composition.

Granular compositions preferably comprise about 5 to about 50% by weight, more preferably 10 to 30% by weight, builder. Surfactant can vary from about 1 to about 75% by weight of the composition. Preferably, the surfactant or surfactants comprise from about 10 to about 60% by weight of the composition, and most preferably from about 20 to about 50% by weight.

Other ingredients will be present in the amount required to achieve the

desired effect. Other ingredients are typically 0 to 20% by weight of the detergent composition.

Granular detergent compositions can be prepared by any of the conventional techniques, such as slurrying the individual components in water and then atomizing and spraying the resulting mixture.

The granules of disintegrant composition are mixed with a granular detergent composition at a concentration of about 1 to about 10 wt%.

Detergent tablets may then be pressed on a Carver press, a single-station punch or rotary tablet press. Preferably, the detergent composition comprises less than 6% water to avoid pre-hydrating the disintegrant composition and reducing its efficacy in use. Detergent tablets are typically made by blending granules of the disintegrant composition with granules of the detergent composition, and then compressing the resulting blend on high-speed rotary or single-station tablet presses.

Tablet disintegration depends on a uniform distribution of disintegrant composition throughout the tablet matrix. If disintegrant powders or very fine particle size disintegrant granules are present, segregation of the component particles may occur. Thus, the disintegrant granules should exhibit a particle size range which approximates that of the detergent granules with which they are to be blended to minimize the potential for segregation.

Agglomeration, for example with Schugi Agglomerators, Patterson- Kelley Zig-Zag blenders, and O-Brien Agglomerators, has been widely used for the production of automatic dish wash detergents and concentrated heavy duty laundry detergents. The process yields the proper density, 0.56 g/cm2 to 0.7 g/cm2, and particle size range,-10 mesh (2000 microns) to +80 mesh (180 microns).

Industrial Applicabilitv The disintegrant granules are particularly suited for the preparation of detergent tablets for dishwashing and laundry use, especially in automatic clothes washers and dishwashers. In laundry use the wash water typically comprises 0.1 to 1% by weight of the detergent composition.

The disintegrant granules have good disintegration performance

and good friability. Due to good intergranule bonding, the disintegrant granule does not fully dissociate upon contact with water into its component fibers, which could leave an undesirable residue on clothes, dishes, and other items. The disintegrant granules are excellent for phosphate-based detergents, and are outstanding for zeolite-based detergents. Detergent tablets prepared from the disintegrant granules have excellent hardness, low friability, and the ability to dissolve completely in wash water in about one minute or less.

The following examples illustrate this invention and are intended as illustrative only, and not as a limitation on the scope of the invention or equivalents thereof. In the examples, all percentages are intended to be weight percent unless a contrary intent is clearly expressed.

EXAMPLES Example 1 5518.5 Kg of softwood sulfite wood pulp containing 2.6% lignin and 13.4% hemicellulose and having a median particle size of 57 microns and a span of 2.1,70.75 Kg of cross-linked carboxymethylcellulose having a median particle size of 50 microns and a span of 1.6, and 70.75 Kg of sodium sulfate was mixed in a Nauta conical screw-type mixer. This resulting blend was then passed through a commercial roller compactor and ground twice, the second time through a 1500 micron screen to remove oversize particles. The granular product was placed on a 315 micron screen to remove all particles that were smaller than 315 microns.

These smaller particles were recycled and mixed with fresh blend before compaction, grinding, and screening to produce more granules of the desired size range.

75 grams of these disintegrant granules were added to 1425 grams of a heavy duty, zeolite-based, laundry detergent formulation containing approximately 13.7% alkyl benzenesulfonate, 7.8% ethoxylated Cis-Cis alcohols with an average of 5 ethylene oxide units, 0.8% soap, 11.1 % sodium carbonate, 22.2% zeolite A, 1.9% sodium silicate, 3.2% of a copolymer commonly used as a detergent builder, 0.5% of a phosphonate, 16.9% perborate monohydrate, 2.6% of an enzyme granulate, 7.4%

ethylenediamine tetraacetate (granular bleaching activator), 3.2% of a silicone antifoaming agent, and 8.5% water. This mixture was blended for 5 minutes in a Patterson-Kelley twin shell blender (Patterson-Kelley, East Stroudsburg, PA), and was then tableted using a Fette single-station tablet machine to produce tablets weighing 25 grams and having a diameter of 36 mm. The hardness of the tablets was 29.4 N, and they disintegrated in tap water at 30°C in 30 seconds.

Example 2 100 grams of the disintegrant composition of Example 1 was added to 1900 grams of a heavy-duty zeolite-based detergent formulation having a bulk density of 0.77 g/cm2 and an average particle size of 674 microns.

The mixture was blended for 5 minutes in a Patterson-Kelley twin shell blender, and was then tableted using a Fette single-station tablet machine to produce tablets weighing 40.1 grams and having a diameter of 45 millimeters. The tablets had a friability of 1.08% (as measured by weight loss of tablets after tumbling at 50 rpm for 1 minute) and an average disintegration time of 31.7 seconds at 24°C in water.

Comparative Example A This example illustrates that the disintegrant behavior provided by granules of the softwood pulp alone is inferior to that provided by granules comprising the softwood pulp plus a disintegrant component.

The powdered softwood pulp containing 2.6% lignin described in Example 1 was compacted into tablets using a Stokes B-2 multiple station tablet pressed. The force used in compaction was 1000 kgs. The tablets were then broken down into granules using a 10 mesh (2000 micron) screen in an Erweka AR 400 granulator. The collected granules were further size fractionated using the Rotap sieve separator. The fractions below 14 mesh (1410 microns) and above 100 mesh (149 microns) were retained for further use.

100 grams of the softwood granules was added to 1900 grams of a heavy-duty zeolite-based detergent formulation having a bulk density of 0.77 g/cm2 and an average particle size of 674 microns. The mixture was

blended for 5 minutes in a Patterson-Kelley twin shell blender, and was then tableted using a Fette single-station tablet machine to produce tablets weighing 38 grams and having a diameter of 45 millimeters. The tablets had a friability of 9.6% (as measured by weight loss of tablets after tumbling at 50 rpm for 1 minute) and an average disintegration time of 69 seconds at 30°C in water.

Comparative Example B 1 gram of cellulose powder Solka Floc 60 which has an average fiber length of 53 microns, a span of 2.7, and contains more than 99% cellulose (Fiber Sales & Development Corporation, Urbana, OH USA), was weighed and placed into a 1.125 in (2.8 cm) die of a hydraulic Carver press. The material was compressed to a final compression force of 12,000 Ibs. Several such wafers were ground through a 10 mesh (2000 micron), and then a 16 mesh (1180 micron) screen. The material passing through the 16 mesh screen was then transferred onto an air jet sieve containing a 40 mesh (425 micron) screen and sieved for 60 seconds. The granular material retained on the screen was used for tableting studies.

3.5 grams of the resulting Solka Floc 60 granules were blended with 66.5 grams of zeolite-based detergent. A quantity of 8.0 grams of the blend was placed into a 1.125 in (2.8 cm) die of a hydraulic Carver press and compressed to a thickness of 1.4 cm. The tablets did not completely disintegrate after two minutes in tap water at 30°C.

Comparative Example C 50 grams of a granular disintegrant ARBOCEL disintegrant (Rettenmeier Co.), which is made from mechanical softwood pulp containing 26.6% lignin, was added to 950 grams of the same zeolite- based detergent formulation as in Example 2. This mixture was blended for 5 minutes in a Patterson-Kelley twin shell blender, and was then tableted using a Fette single-station tablet machine to produce tablets weighing 40.7 grams and having a diameter of 45 mm. The tablets had a friability of 5.7% and an average disintegration time of 65.6 seconds at 20°C.

6.5 g of the same grade of ARBOCEL disintegrant was blended with 123.5 g zeolite-based detergent. A portion (8.0 g) of the blend was placed in a 1.125 in. (2.8 cm) die of a hydraulic Carver press and compressed to a thickness of 1.4 cm. The tablets disintegrated in 34 seconds in tap water when tested at a higher water temperature of 30°C.

Example 3 The particle size of a 75: 25 blend of powdered hardwood and softwood pulp containing 0.36% lignin and having an average particle size of 51.2 microns was measured in i-propyl alcohol with Horiba LA-910 particle size analyzer. This pulp showed minimal swelling of 1.4% in water as indicated by an increase in average particle size to 51.9 microns when measured in water. The pulp was mixed with 1.25% cross-linked carboxymethylcellulose (XL-CMC) and 1.25% sodium sulfate and compacted into tablets using a Stokes B-2 multiple station tablet press.

The force used to compact the tablets 1046 kg. The tablets were then broken down into granules using a 10 mesh (2000 micron) screen in an Erweka AR 400 granules. The collected granules were further screened using 14 mesh (1410 micron) and 100 mesh (149 micron) screens using the Rotap sieve separator. The fractions below 14 mesh (1410 micron) and above 100 mesh (149 micron) were retained for further work.

100 grams of this granular disintegrant composition was added to 1900 grams of a heavy-duty zeolite-based laundry detergent formulation having a bulk density of 0.77 g/cm2 and an average particle size of 674 microns.. This mixture was blended for 5 minutes in a Patterson-Kelley twin shell blender, and was then tableted using a Fette single-station tablet machine to produce tablets weighing 40.7 grams and having a diameter of 45 mm. The tablets had a friability of 4.1 %, and an average disintegration time at 20°C of 41.4 seconds.

The zeolite-based detergent without any added disintegrant gave 40 gram, 45 mm tablets having a friability of 6.7% and an average disintegration time at 20°C of greater than 120 seconds.

Example 4

Granules were prepared according to Example 3 except that the hardwood pulp was mixed with 5.0% cross-linked carboxymethyl cellulose and 1.25% anhydrous sodium sulfate prior to compaction in a Pharmapaktor roller compactor at 40 to 50 kN. The material was ground through a US mesh 14 (1410 micron) and sieved to finer than 16 US mesh (1190 micron) and coarser than 100 US mesh (149 micron).

100 grams of this granular disintegrant was added to 1900 grams of a heavy-duty zeolite-based laundry detergent formulation. This mixture was blended for 5 minutes in a Patterson-Kelley twin shell blender, and was then tableted using a Fette single-station tablet machine to produce tablets weighing 40 grams and having a diameter of 45 mm. The tablets had a friability of 5.0%, and an average disintegration time at 20°C of 35.4 seconds.

Example 5 Granules were prepared according to Example 3 except that AVICELO 200 microcrystalline cellulose (FMC Corp, Philadelphia, PA, USA) was used as the cellulose component. This material, which has an average diameter of 230 microns and a span of 1.2, and in which the largest particles are 780 microns and the smallest particles are 15 microns, as measured in water with a Horiba LA-910 particle size analyzer, contains 0% lignin. The composition was compacted using a Stokes B-2 multiple station tablet press at a force of 500 kilograms and then granulated. The granules were size fractionated to retain the granules between 100 mesh (149 microns) and 14 mesh (1410 microns).

100 grams of this granular disintegrant was blended with 1900 grams of a heavy duty zeolite-based laundry detergent formulation and then tableted as described in Example 2. The tablets weighed 40 grams and had a diameter of 45 mm. They had a friability of 1.66% and an average disintegration time of 45 seconds at 24°C.

Granules were similarly made from AVICELO PH200 microcrystalline cellulose plus 2.5% of cross-linked carboxymethylcellulose. Tablets prepared from this composition had a

diameter of 45 millimeters and weighed 39.8 grams. They had a friability of 2.6% and an average disintegration time of 31 seconds at 24°C.

100 grams of ungranulated AVICELO PH200 microcrystalline cellulose powder was added to 1900 grams of a heavy duty zeolite-based laundry detergent formulation and then tableted as described in Example 2. The tablets had a friability of 3.3% and an average disintegration time of 70 seconds at 24°C.

Example 6 75 grams of the granular disintegrant prepared in Example 1 was added to 1425 grams of a heavy duty, phosphate-based, laundry detergent formulation containing 28. 0% sodium tripolyphosphate, 20.7% sodium carbonate, 4.8% sodium zeolite, 4.3% sodium citrate, 2.4% sodium polyacrylate, 1.7% sodium silicate, 4.6% sodium sulfate, 16. 9% anionic surfactants, 3.2% nonionic surfactants, and 13.2% water. This mixture was blended for 5 minutes in a Patterson-Kelley twin shell blender, and was then tableted using a Fette single-station tablet machine to produce tablets weighing 25 grams and having a diameter of 36 mm. The hardness of the tablets was 26.5 N, and they disintegrated in tap water at 20°C in 32 seconds Comparative Example D 75 grams of the granular ARBOCEL disintegrant used in Comparative Example C was blended with 1425 grams of the same phosphate-based detergent formulation as in Example 6. This mixture was tableted to produce tablets weighing 25 grams and having a diameter of 36 mm. The hardness of these tablets was 22.5 N, and they disintegrated in tap water at 20°C in 43 seconds.

Example 7 100 grams of the granular disintegrant prepared in Example 3 was added to 1900 grams of a heavy-duty phosphate-based laundry detergent formulation having a bulk density of 0.79 g/cm2 and an average particle

size of 400 microns. This mixture was blended for 5 minutes in a Patterson-Kelley twin shell blender, and was then tableted using a Fette single-station tablet machine to produce tablets weighing 40 grams and having a diameter of 45 mm. The tablets had a friability of 1.7% and an average disintegration time at 25°C of 40.7 seconds.

Granules were prepared using the same 75: 25 blend of hardwood and softwood pulp but without any other ingredients. When evaluated at the same 5% weight loading, the 40 gram, 45 mm tablets produced had a friability of 4.37% and an average disintegration time in water at 24°C of 38 seconds.

The phosphate detergent base without added disintegrant produced tablets having a friability of 2.5% and an average disintegration time at 25°C of 55 seconds.

Example 8 100 grams of the granular disintegrant prepared in Example 4 was added to 1900 grams of a heavy-duty phosphate-based laundry detergent formulation. This mixture was blended for 5 minutes in a Patterson-Kelley twin shell blender, and was then tableted using a Fette single-station tablet machine to produce tablets weighing 39.7 grams and having a diameter of 45 mm. The tablets had a friability of 4.2% and an average disintegration time at 25°C of 26 seconds.

Example 9 Granules were tested for water absorptivity as a potential indicator of disintegrant performance. About 3 grams of sample prepared as described was added to a tared plastic centrifuge tube. Deionized water was added to the tube containing the sample until the tube was approximately 75% full. The centrifuge tube contents were then stirred until the solid was dispersed. The dispersion was then centrifuged for 10 minutes at 3000 rpm, and the supernatant decanted. The tubes were weighed with the sediments, and the weight of the wet sediment determined. The water binding capacity, defined as the water absorbed as a percentage of the weight of the sample, is tabulated in Table 1. Water

absorptivity alone did not correlate to the shortest tablet disintegration time.

The friability of the granules was tested by abrading the granules in an abrasion drum with 200 4-mm glass beads at 25 rpm for 10 minutes.

The material that passed through a 40 mesh screen was collected and weighed. The granule friability, defined as the weight of the fraction of particles passing through the 40 mesh screen divided by the weight of the total sample before abrasion multiplied by 100, is tabulated in Table 1.

Table I. Summary of Water Absorptivity & Granule Friability Example Absorptivity Friability Solka Floc60 (<1% lignin) 322% 13% Ground softwood (27.3% lignin) 635% 18% ARBOCEL@ disintegrant (26. 6%) ignin) 586% 20% Softwood sulfite pulp + 7.5% XL-CMCa 611 % 19% Softwood sulfite pulp (2. 6% lignin) 413% 17% Softwood sulfite pulp + 1. 25% sodium 346% ND b sulfate Softwood sulfite pulp + 1. 25% sodium 359% ND sulfate + 1. 25% XL-PVP° Softwood sulfite pulp + 1. 25% sodium 357% ND sulfate + 5.0% XL-PVP Softwood sulfite pulp + 10% sodium 358% ND sulfate + 1. 25% XL-CMC Softwood sulfite pulp + 15% sodium 346% ND sulfate + 1. 25% XL-CMC 75: 25 Mixture of hardwood sulfite pulp and 362% ND softwood sulfite pulp + 1.25% sodium sulfate + 1. 25% XL-CMC 75: 25 Mixture of hardwood sulfite pulp and 426% ND softwood sulfite pulp + 1.25% sodium sulfate + 5.0% XL-CMC Softwood sulfite pulp + 1.25% sodium 495% 7% sulfate + 1. 25% XL-CMC Softwood sulfite pulp + 1. 25% sodium 466% ND sulfate + 5.0% XL-CMC Softwood sulfite pulp + 1. 25% sodium 515% ND sulfate + 10% XL-CMC aCross-linked carboxymethylcellulose. bNot determined.

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Having described the invention, we now claim the following and their equivalents.