EP1076686B1

EP1076686B1 - A process for producing a water-dispersable non-particulate detergent product from low-density particulate detergent particles

Info

Publication number: EP1076686B1
Application number: EP99912004A
Authority: EP
Inventors: Adrian John Waynforth Angell; Les Charles Zorb; Thomas Edward Stone
Original assignee: Procter and Gamble Co
Current assignee: Procter and Gamble Co
Priority date: 1998-04-27
Filing date: 1999-04-21
Publication date: 2004-03-03
Anticipated expiration: 2019-04-21
Also published as: DE69915276T2; CA2329243A1; CN1307631A; DE69915276D1; ES2217743T3; WO1999055821A1; JP2002513074A; BR9909960A; AR015027A1; AU3049899A; EP1076686A1; ATE260968T1

Description

TECHNICAL FIELD

The present invention relates to a process for making a non-particulate detergent product, such as a tablet, block, or bar which sinks in water. readily disintegrates in water and is rapidly dispersible in water, by using a low density particulate detergent composition having a particulate bulk density less than 800 g/l as a starting material.

BACKGROUND OF THE INVENTION

Non-particulate detergents are an attractive alternative to granular or particulate forms of detergents from the standpoint of simplifying the dosing of such detergents for automatic laundry or dishwashing machines. Non-particulate detergents are usually supplied in the form of bars, tablets or briquettes and they not only prevent spillage of the detergent composition but also eliminate the need for the consumer to estimate the correct dosage of the detergent composition per wash. Non-particulate detergents minimize the contact by the consumer with the detergent.
An important factor for successful performance of a non-particulate detergent is its ability to disintegrate and dissolve in the washing machine in a controlled manner according to a desired dissolution profile during the program cycle of the machine. Another important performance factor is that the non-particulate detergent should be hard enough to facilitate easy handling of the detergent prior to use, so that it does not inadvertently lose its structure, crumble, or deteriorate, both during the packaging, transport and storage and during handling by the end consumer prior to actual use.
Additionally, a very desirable feature of a non-particulate detergent, such as for example, a tablet, is its ability to sink in water and rapidly disperse in water to form a wash solution. In order to sink in water, a detergent tablet must have a density greater than 1000 g/l and in order to disperse in water. a detergent tablet must be able to break up in water. However. when laundry tablets are made from low bulk density detergents, such as those made by spray dried processes. wherein the detergent powder has a bulk density less than 650 g/l. the problem frequently encountered is that the force required to compact the detergent powder into tablets having a density of at least 1000 g/l is so high that the detergent tablets do not readily disperse in water. This problem is further escalated by the fact that detergent powders made from spray dried processes tend to be more porous and sticky. Thus when these detergent powders are pressed into tablets having a density of at least 1000 g/l, the powder particles stick together and consequently the tablet does not readily break up and dissolve in water. Conversely, if the tablets made from low bulk density detergent powders are compacted using a lower force, they generally disperse in water but at a slower rate because they have a density less than 1000 g/l and thus tend to float in water before fully dispersing in water.
The above problem is usually not encountered when making detergent tablets from a detergent powder made by agglomeration processes because detergent powders made by agglomeration processes usually have a bulk density in a range of 700 g/l to 850 g/l and consequently, the force required to compress the powder into a tablet having a density of at least 1000 g/l is not so high. Thus detergent tablets made by compacting detergent powders made from agglomeration process usually sink in water. However, agglomeration process detergents or "agglomerates", which inherently have higher density than spray dried process detergents or "spray dried granules", generally exhibit slower dissolution rates in water, as compared to spray dried granules.
Thus the production of detergent tablets is a complex matter. It involves more than the mere selection of components or the compression of a particular detergent composition into a tablet. The tablet must be capable of withstanding the shocks of packaging, handling and distribution without crumbling. In other words the tablet must be strong. But the tablet must also have a satisfactory rate of disintegration when immersed in water. The tablets known so far have generally shown too long a disintegration time, in favor of their strength, or they have had a very low strength, in favor of their shorter disintegration time.
It is highly desirable to have a laundry detergent tablet with a core which is formed by compressing a particulate material which has a detersive surfactant and a builder and wherein the particulate material has a bulk density less than 850 g/l so that the detergent tablet formed by compressing such a particulate material not only sinks in water but also rapidly disintegrates and readily dissolves in water.
This kind of a tablet performance has heretofore not been available and this level of performance requires not only careful selection of the type of detergent that makes up the core, but also a carefully selected density range of the particulate detergent to improve the dissolution of the detergent. To achieve a particulate detergent bulk density within an optimal range, it is desirable to exploit not only the benefits of using mixtures of spray dried granules and agglomerates but also processing the detergent particles in a manner so as to reduce their inherent porosity and bring that particle porosity within an optimally desired range, prior to the step of compacting that detergent particles into a non-particulate form. It is thus necessary to carefully tailor the particle porosity of the particulate detergent prior to compaction. The present invention overcomes the problems as set forth above.

BACKGROUND ART

The prior art is replete with methods of forming tablets and coating tablets.
One approach has been to use acetate salt to improve the dissolution rate of detergents compressed in the form of tablets. EP-A-0002293, published on 13^th June 1979, discloses detergent tablets containing hydrated salt. The preferred hydrate salt is a mixture of sodium acetate trihydrate and sodium metaborate tetrahydrate.
Another approach known in the art is to use effervescent aids to improve tablet disintegration. CA-A-2040307 discloses lundry detergent tablets comprising anionic surfactants mixed with sodium carbonate and citric acid.
As far as coated tablets are concerned, GB-A-0 989 683, published on 22nd April 1965, discloses a process for preparing a particulate detergent from surfactants and inorganic salts; spraying on water-soluble silicate; and pressing the detergent particles into a solid form-retaining tablet. Finally a readily water-soluble organic film-forming polymer (for example, polyvinyl alcohol) provides a coating to make the detergent tablet resistant to abrasion and accidental breakage.
European publication, EP-A-0 002 293, published on 13th June 1979. discloses a tablet coating comprising hydrated salt such as acetate. metaborate. orthophosphate, tartrate, and sulphate. Another Euaopean publication. EP-A-0 716 144, published on 12th June 1996, also discloses laundry detergent tablets with water-soluble coatings which may be organic polymers including acrylic/maleic copolymer, polyethylene glycol, PVPVA, and sugar.
U.S. Patent No. 5,658,874, issued on Aug. 19, 1997 to Alan P. Davies et al. and assigned to Lever Brothers Company, discloses a process for making tablets of a detergent composition comprising detergent active compound, detergency builder and other ingredients, in which at least some particles of the composition are individually coated with a material that functions as a binder and a disintegrant capable, when the tablet is immersed in water, for disrupting the structure of the tablet. However, this patent discloses the use of high molecular weight binders that generally lead to tablets that are more porous. US-A-4,451,386 discloses a process for producing detergent tablets from free-flowing spray-dried builder beads. EP-A-576,234 discloses a dispensing device for laundry tablets.

SUMMARY OF THE INVENTION

The invention meets the needs above by providing a process for producing a water-dispersible, non-particulate detergent product. Specifically, in one aspect of the present invention, the process includes the step of providing a low density particulate detergent composition having a bulk density in a range of from 400 g/l to 850 g/l and having an intra-particle porosity in a range of from 5% to 90% by volume. The process further includes the step of adding a liquid to the low density particulate detergent composition in an amount sufficient to reduce the intra-particle porosity by at least 10%. The process then includes the step of compacting the low density particulate detergent composition having reduced intra-particle porosity by applying a pressure in an amount sufficient to form the water-dispersible non-particulate detergent product having a density of at least about 1000 g/l.
In yet another aspect of the present invention, a process for producing a water-dispersible, non-particulate detergent product from a low density detergent composition is disclosed. The process includes the steps of providing spray dried detergent granules having a bulk density in a range of from 600 g/l to 850 g/l. The process further include the step of providing agglomerated detergent particles having a bulk density in a range of from 625 g/l to 725 g/l. The process still further includes the steps of mixing the spray dried detergent granules and the agglomerated detergent particles to form a low density detergent composition, wherein the spray dried detergent granules are present in a range of from 40% to 80% by weight of the low density detergent composition and the agglomerated detergent particles are present in a range of from 20% to 60% by weight of the low density detergent composition. The process also includes the step of adding a liquid to the low density detergent composition in an amount sufficient to reduce said intra-particle porosity by at least 10%, and compacting the low density detergent composition having the aforementioned reduced intra-particle porosity, by applying a pressure in an amount sufficient to form the water-dispersible, non-particulate detergent product having a density of at least 1000 g/l.

DETAILED DESCRIPTION OF THE INVENTION

Process

In the preferred embodiment of the present invention, the process includes the step of providing a low density particulate detergent composition having an intra-particle porosity desirably, in a range of from 10% to 90% by volume. Preferably, the porosity is in a range of from 15% to 70% by volume and most preferably, the porosity is in a range of from 20% to 65% by volume. This porosity is measured by a Mercury Porosimeter, which technique is well known to those skilled in the art and need not be described in any detail here.

The particulate detergent composition

The term "particulate" as used herein means forms such as powders, granules, particles, flakes and other similar particulate forms that are capable of being compacted into a more dense non-particulate form.
In particular for laundry tablets, detergent particles having ingredients such as builder and surfactant can be spray-dried in a conventional manner and then compacted at a suitable pressure. The surfactants and builders normally provide a substantial part of the cleaning power of the tablet. The term "builder" is intended to mean all materials which tend to remove calcium ion from solution, either by ion exchange, complexation, sequestration or precipitation.
The particulate material used for making the detergent tablet provided in this invention can be made by any particulation or granulation process. An example of such a process is spray drying (in a co-current or counter current spray drying tower) which typically gives "spray-dried" detergent granules having low bulk densities of 600g/l or lower. Particulate materials of higher density can be prepared by granulation and densification in a high shear batch mixer/granulator or by a continuous granulation and densification process (e.g. using Lodige® CB and/or Lodige® KM mixers). Other suitable processes include fluid bed processes, compaction processes (e.g. roll compaction), extrusion, as well as any particulate material made by any chemical process like flocculation, crystallization sentering, etc. The individual particles can also be in any other form, such as for example, particle, granule, sphere or grain.
The particulate materials may be mixed together by any conventional means, for example, a concrete mixer, Nauta mixer, ribbon mixer or any other. Alternatively the mixing process may be carried out continuously by metering each component by weight on to a moving belt, and blending them in one or more drum(s) or mixer(s). A liquid spray-on to the mix of particulate materials (e.g. non-ionic surfactants) may be carried out. Other liquid ingredients may also be sprayed on to the mix of particulate materials either separately or premixed. For example perfume and slurries of optical brighteners may be sprayed. A finely divided flow aid (dusting agent such as zeolites, carbonates, silicas) can be added to the particulate materials after spraying the non-ionic, preferably towards the end of the process, to make the mix less sticky.
The detergent particles can be made by an agglomerate process comprising the steps of:
i) admixing one or more detergent surfactants, a perborate component and an acid source and optionally other detergent ingredients to form a mixture; and
ii) agglomerating the mixture to form agglomerated particles or "agglomerates".
Typically, such an agglomeration process involves mixing an effective amount of powder, including the acid source, with a high active surfactant paste in one or more agglomerators such as a pan agglomerator, a Z-blade mixer or more preferably in-line mixers, preferably two, such as those manufactured by Schugi (Holland) BV, 29 Chroomstraat 8211 AS, Lelystad. Netherlands, and Gebruder Lodige Maschinenbau GmbH, D-4790 Paderbom 1. Elsenerstrasse 7-9. Postfach 2050, Germany. Preferably a high shear mixer is used. such as a Lodige CB (Trade Name). Most preferably, a high shear mixer is used in combination with a low shear mixer, such as a Lodige CB (Trade Name) and a Lodige KM (Trade name) or Schugi KM (Trade Name). Optionally, only one or more low shear mixer are used. Preferably. the agglomerates are thereafter dried and/ or cooled.
Another agglomeration process involves mixing of various components of the final agglomerate in different stages, using an fluidized bed. For example, a preferred particulate detergent in accordance with the present invention can be agglomerated by addition, preferably by spraying on, of nonionic, anionic surfactants and optionally a wax, or mixtures thereof, to the acid source in powdered form and other optional ingredients. Then, additional components. including the perborate bleach and optinally the alkali source or part thereof, can be added and agglomerated in one or more stages, thus forming the final agglomerate particle.
The agglomerates may take the form of flakes, prills, marumes. noodles, ribbons, but preferably take the form of granules. A preferred way to process the particles is by agglomerating powders (e.g. aluminosilicate, carbonate) with high active surfactant pastes and to control the particle size of the resulting agglomerates within specified limits. Typical particle sizes are from 0.10 mm to 5.0 mm in diameter, preferably from 0.25 mm to 3.0 mm in diameter, most preferably from 0.40 mm to 1.00 mm in diameter. Typically, the "agglomerates" have a bulk density desirably ,of at least 700 g/l and preferably, in a range of from 700 g/l to about 900 g/l.
A high active surfactant paste comprising a mix of, typically, from 50% by weight to 95% by weight, preferably 70% by weight to 85% by weight of surfactant, and optionally it can contain an appropriate acid source. The paste may be pumped into the agglomerator at a temperature high enough to maintain a pumpable viscosity, but low enough to avoid degradation of the anionic surfactants used. An operating temperature of the paste of 50°C to 80°C is typical. Such pastes and methods for making and processing such pastes is for example described in WO 93/03128. In an especially preferred embodiment of the present invention, the detergent particles made by agglomeration process have a bulk density of greater than 400 g/l and the detergent is in the form of powder or a granulate.
In the preferred embodiment of the present invention. the particulate detergent composition is a mixture of spray dried process and agglomeration process detergents, such that the final bulk density of the detergent composition is in a range of desirably, no greater than 900 g/l, more desirably, in a range of from 400 g/l to 850 g/l, preferably in a range from 600 g/l to 850 g/l and more preferably, in a range of from 625 g/l to 725 g/l. These ranges of bulk density are desirable because if the bulk density of the particulate detergent from which the tablet is to be compressed is greater than 900 g/l, then the solubility of the detergent tablet will be detrimentally affected. A bulk density less than 400, preferably 600 g/l, is undesirable because at values less than 400 g/l, preferably 600 g/l, the amount of pressure required to form a detergent tablet having a density of at least 1000 g/l is so high that the tablet will not break up easily in water and will not dissolve rapidly.
To achieve the desired bulk densities as set forth above, the particulate detergent composition contains selected amounts of spray dried granules and detergent agglomerates in an optimum proportion. In this regard, the composition comprises desirably from 40% to 80%, preferably from 40% to 60%, and more preferably from 45% to 55%, by weight, of spray dried. Desirably, the composition includes from 20% to 60%, preferably from 40% to 60%, and more preferably from 45% to 55%, by weight, of agglomerates.

Addition of Liquid to reduce porosity of detertzent particles

In the preferred embodiment of the present invention, the process further includes the step of adding a liquid to the low density particulate detergent composition in an amount sufficient to reduce the intra-particle porosity by at least 10%. It is desirable to reduce the intra-particle porosity by at least 10%, and preferably by at least 20%, because if the porosity reduction is less than 10%, no appreciable dispersibility of the detergent tablet is expected. Without being bound to a specific theory, it is theorized that the porosity reduction of the spray dried granules and agglomerates, and the resultant increase in particle density, causes the agglomerates to harden while the spray dried granules remain relatively softer. When a pressure is applied to compact the detergent particle mixture into a tablet, for example. there is believed to me some mechanical interlocking between the hard agglomerated and the softer spray dried granules. The spray dried granules are believed to "flow" into the interstitial spaces between the particles, thereby increasing the mechanical bonding between the particles upon the application of pressure. This results in the formation of a detergent tablet that is not only strong and can resist breakage, but also can disintegrate rapidly in water because the detergent particles do not "stick" together. Due to the mixture of spray dried granules and agglomerates in the composition, the dissolution rate of the detergent tablet is also increased because of the faster solubility of spray dried particles in water.
Any liquid for reducing porosity can be used to carry out the invention, however non-ionics are preferred as they also provide detergency benefits. Suitable nonionic surfactants include compounds produced by the condensation of alkylene oxide groups (hydrophilic in nature) with an organic hydrophobic compound, which may be aliphatic or alkyl aromatic in nature. The length of the polyoxyalkylene group which is condensed with any particular hydrophobic group can be readily adjusted to yield a water-soluble compound having the desired degree of balance between hydrophilic and hydrophobic elements. Other examples are nonionic surfactants such as the polyethylene oxide condensates of alkyl phenols, e.g., the condensation products of alkyl phenols having an alkyl group containing from 6 to 16 carbon atoms, in either a straight chain or branched chain configuration, with from 4 to 25 moles of ethylene oxide per mole of alkyl phenol. Still other nonionics are the water-soluble condensation products of aliphatic alcohols containing from 8 to 22 carbon atoms, in either straight chain or branched configuration, with an average of up to 25 moles of ethylene oxide per more of alcohol.
Polyhydroxy fatty acid amides may be produced by reacting a fatty acid ester and an N-alkyl polyhydroxy amine. The preferred amine for use in the present invention is N-(R1)--CH2(CH2OH)4--CH2--OH, where R1 is typically a alkyl, e.g. methyl group; and the preferred ester is a C 12-C20 fatty acid methyl ester. Methods of manufacturing polyhydroxy fatty acid amides have been described in WO 92 6073, published on 16th Apr.. 1992. This application describes the preparation of polyhydroxy fatty acid amides in the presence of solvents. In a highly preferred embodiment of the invention N-methyl glucamine is reacted with a C 12-C20 methyl ester. It also says that the formulator of granular detergent compositions may find it convenient to run the amidation reaction in the presence of solvents which comprise alkoxylated. especially ethoxylated (EO 3-8) C12-C14 alcohols (page 15, lines 22-27). This can directly yield nonionic surfactant systems which are preferred in the present invention, such as those comprising N-methyl glucosamide and C12-C14 alcohols with an average of 3 ethoxylate groups per molecule. Nonionic surfactant systems, and granular detergents made from such systems have been described in WO 92 6160, published on 16th Apr., 1992. This application describes (example 15) a granular detergent composition prepared by fine dispersion mixing in an Eirich RV02 mixer which comprises N-methyl glucosamide (10%), nonionic surfactant (10%). Both of these patent applications describe nonionic surfactant systems together with suitable manufacturing processes for their synthesis, which have been found to be suitable for use in the present invention.
Other nonionic surfactants which may be used as components of the surfactant systems herein include ethoxylated nonionic surfactants, glycerol ethers, glucosamides, glycerol amides, glycerol esters, fatty acids, fatty acid esters, fatty amides, alkyl polyglucosides, alkyl polyglycol ethers, polyethylene glycols, ethoxylated alkyl phenols and mixtures thereof.
In the preferred embodiment, the liquid used is one of ionic surfactants, anionic surfactants, water and polyethylene glycol, and mixtures thereof. Preferably, the liquid is a nonionic surfactant, and more preferably, it is polyethylene glycol (PEG). Most preferably, the PEG has a molecular weight of less than about 1000 and in the best mode, the molecular weight of PEG is 200. In the preferred embodiment, PEG is added to the detergent composition in a range of from 0.1% to 10% by weight and preferably 5% by weight. In the preferred embodiment. the addition of PEG having a molecular weight of about 200 results in a porosity reduction in a range of 5% to 200%.

Drv Detergent Material

The starting dry detergent material of the present process preferably comprises materials selected from the group consisting of carbonates, sulfates. carbonate/sulfate complexes. tripolyphosphates, tetrasodium pyrophosphate. citrates. aluminosilicates, cellulose-based materials and organic synthetic polymeric absorbent gelling materials. More preferably, the dry detergent material is selected from the group consisting of aluminosilicates, carbonates. sulfates, carbonate/sulfate complexes, and mixtures thereof. Most preferably, the dry detergent material comprise a detergent aluminosilicate builder which are referenced as aluminosilicate ion exchange materials and sodium carbonate.
The aluminosilicate ion exchange materials used herein as a detergent builder preferably have both a high calcium ion exchange capacity and a high exchange rate. Without intending to be limited by theory, it is believed that such high calcium ion exchange rate and capacity are a function of several interrelated factors which derive from the method by which the aluminosilicate ion exchange material is produced. In that regard, the aluminosilicate ion exchange materials used herein are preferably produced in accordance with Corkill et al. U.S. Patent No. 4,605,509 (Pocter & Gamble).
Preferably, the aluminosilicate ion exchange material is in "sodium" form since the potassium and hydrogen forms of the instant aluminosilicate do not exhibit the as high of an exchange rate and capacity as provided by the sodium form. Additionally, the aluminosilicate ion exchange material preferably is in over dried form so as to facilitate production of crisp detergent agglomerates as described herein. The aluminosilicate ion exchange materials used herein preferably have particle size diameters which optimize their effectiveness as detergent builders. The term "particle size diameter" as used herein represents the average particle size diameter of a given aluminosilicate ion exchange material as determined by conventional analytical techniques, such as microscopic determination and scanning electron microscope (SEM). The preferred particle size diameter of the aluminosilicate is from 0.1 µm (micron) to 10 µm (microns), more preferably from 0.5 µm (microns) to 9 µm (microns). Most preferably, the particle size diameter is from 1 µm (microns) to 8 µm (microns).
Preferably, the aluminosilicate ion exchange material has the formula Na_z[(AlO₂)_z.(SiO₂)_y]xH₂O wherein z and y are integers of at least 6, the molar ratio of z to y is from about I to about 5 and x is from about 10 to about 264. More preferably. the aluminosilicate has the formula Na₁₂[(AlO₂)₁₂.(SiO₂)₁₂]xH₂O wherein x is from about 20 to about 30, preferably about 27. These preferred aluminosilicates are available commercially, for example under designations Zeolite A, Zeolite B and Zeolite X. Alternatively, naturally-occurring or synthetically derived aluminosilicate ion exchange materials suitable for use herein can be made as described in Krummel et al, U.S. Patent No. 3,985,669.
The aluminosilicates used herein are further characterized by their ion exchange capacity which is at least about 200 mg equivalent of CaCO₃ hardness/gram, calculated on an anhydrous basis, and which is preferably in a range from about 300 to 352 mg equivalent of CaCO₃ hardness/gram. Additionally, the instant aluminosilicate ion exchange materials are still further characterized by their calcium ion exchange rate which is at least about 2 grains Ca⁺⁺/gallon/minute/-gram/gallon, and more preferably in a range from about 2 grains Ca⁺⁺/gallon/minute/-gram/gallon to about 6 grains Ca⁺⁺/gallon/minute/-gram/gallon.
Additionally, those builder materials discussed previously as an optional coating agent can be used herein. These particular builder materials have the formula (M_x)_i Ca_y (CO₃)_z wherein x and i are integers from 1 to 15, y is an integer from 1 to 10, z is an integer from 2 to 25, M_i are cations, at least one of which is a water-soluble, and the equation Σ_i = _1-15(x_i multiplied by the valence of M_i) + 2y = 2z is satisfied such that the formula has a neutral or "balanced" charge. Additional details and examples of these builder materials have been set forth previously. Preferably, these builder materials are selected from the group consisting of Na₂Ca(CO₃)₂, K₂Ca(CO₃)₂, Na₂Ca₂(CO₃)₃, NaKCa(CO₃)₂, NaKCa₂(CO₃)₃. K₂Ca₂(CO₃)₃, and combinations thereof.

Adjunct Detergent Ingredients

The starting dry detergent material in the present process can include additional detergent ingredients and/or, any number of additional ingredients can be incorporated in the detergent composition during subsequent steps of the present process. These adjunct ingredients include other detergency builders, bleaches. bleach activators. suds boosters or suds suppressors, anti-tarnish and anticorrosion agents. soil suspending agents, soil release agents, germicides, pH adjusting agents, non-builder alkalinity sources, chelating agents, smectite clays, enzymes, enzyme-stabilizing agents and perfumes. See U.S. Patent 3,936,537, issued February 3, 1976 to Baskerville, Jr. et al..
Other builders can be generally selected from the various water-soluble, alkali metal, ammonium or substituted ammonium phosphates. polyphosphates, phosphonates, polyphosphonates, carbonates, borates, polyhydroxy sulfonates, polyacetates, carboxylates, and polycarboxylates. Preferred are the alkali metal, especially sodium, salts of the above. Preferred for use herein are the phosphates, carbonates, C_10-18 fatty acids, polycarboxylates, and mixtures thereof. More preferred are sodium tripolyphosphate, tetrasodium pyrophosphate, citrate, tartrate mono- and di-succinates, and mixtures thereof (see below).
In comparison with amorphous sodium silicates, crystalline layered sodium silicates exhibit a clearly increased calcium and magnesium ion exchange capacity. In addition, the layered sodium silicates prefer magnesium ions over calcium ions, a feature necessary to insure that substantially all of the "hardness" is removed from the wash water. These crystalline layered sodium silicates, however, are generally more expensive than amorphous silicates as well as other builders. Accordingly, in order to provide an economically feasible laundry detergent, the proportion of crystalline layered sodium silicates used must be determined judiciously.
The crystalline layered sodium silicates suitable for use herein preferably have the formula NaMSi_xO_2x+1.yH₂O wherein M is sodium or hydrogen, x is from 1.9 to 4 and y is from 0 to 20. More preferably, the crystalline layered sodium silicate has the formula NaMSi₂O₅.yH₂O wherein M is sodium or hydrogen, and y is from 0 to 20. These and other crystalline layered sodium silicates are discussed in Corkill et al. U.S. Patent No. 4,605,509.
Specific examples of inorganic phosphate builders are sodium and potassium tripolyphosphate, pyrophosphate, polymeric metaphosphate having a degree of polymerization of from 6 to 21, and orthophosphates. Examples of polyphosphonate builders are the sodium and potassium salts of ethylene diphosphonic acid, the sodium and potassium salts of ethane 1-hydroxy-1, 1-diphosphonic acid and the sodium and potassium salts of ethane, 1,1,2-triphosphonic acid. Other phosphorus builder compounds are disclosed in U.S. Patents 3,159,581; 3,213,030; 3,422,021; 3,422,137; 3,400,176 and 3,400,148.
Examples of nonphosphorus, inorganic builders are tetraborate decahydrate and silicates having a weight ratio of SiO₂ to alkali metal oxide of from about 0.5 to about 4.0, preferably from about 1.0 to about 2.4. Water-soluble, nonphosphorus organic builders useful herein include the various alkali metal, ammonium and substituted ammonium polyacetates, carboxylates, polycarboxylates and polyhydroxy sulfonates. Examples of polyacetate and polycarboxylate builders are the sodium, potassium, lithium, ammonium and substituted ammonium salts of ethylene diamine tetraacetic acid, nitrilotriacetic acid, oxydisuccinic acid, mellitic acid, benzene polycarboxylic acids, and citric acid.
Polymeric polycarboxylate builders are set forth in U.S. Patent 3,308,067, Diehl, issued March 7, 1967. Such materials include the water-soluble salts of homo- and copolymers of aliphatic carboxylic acids such as maleic acid, itaconic acid, mesaconic acid, fumaric acid, aconitic acid, citraconic acid and methylene malonic acid. Some of these materials are useful as the water-soluble anionic polymer as hereinafter described, but only if in intimate admixture with the non-soap anionic surfactant.
Other suitable polycarboxylates for use herein are the polyacetal carboxylates described in U.S. Patent 4,144,226, issued March 13, 1979 to Crutchfield et al. and U.S. Patent 4,246,495, issued March 27, 1979 to Crutchfield et al. These polyacetal carboxylates can be prepared by bringing together under polymerization conditions an ester of glyoxylic acid and a polymerization initiator. The resulting polyacetal carboxylate ester is then attached to chemically stable end groups to stabilize the polyacetal carboxylate against rapid depolymerization in alkaline solution, converted to the corresponding salt, and added to a detergent composition. Particularly preferred polycarboxylate builders are the ether carboxylate builder compositions comprising a combination of tartrate monosuccinate and tartrate disuccinate described in U.S. Patent 4,663,071, Bush et al., issued May 5, 1987.
Bleaching agents and activators are described in U.S. Patent 4,412,934, Chung et al., issued November 1, 1983, and in U.S. Patent 4,483,781, Hartman, issued November 20, 1984. Chelating agents are also described in U.S. Patent 4,663,071, Bush et al., from Column 17, line 54 through Column 18, line 68. Suds modifiers are also optional ingredients and are described in U.S. Patents 3,933,672, issued January 20, 1976 to Bartoletta et al., and 4,136,045, issued January 23, 1979 to Gault et al.
Suitable smectite clays for use herein are described in U.S. Patent 4,762,645, Tucker et al, issued August 9, 1988, Column 6, line 3 through Column 7, line 24. Suitable additional detergency builders for use herein are enumerated in the Baskerville patent, Column 13, line 54 through Column 16, line 16, and in U.S. Patent 4,663,071, Bush et al, issued May 5, 1987.

The non-particulate detergent product

The detergent tablets can be prepared simply by mixing the solid ingredients together and compressing the mixture in a conventional tablet press as used, for example, in the pharmaceutical industry.
The detergent tablets provided can be made in any size or shape. Prior to compaction, the detergent particles may be surface treated with a flow aid according to the present invention. The detergent tablets provided may be manufactured by using any compacting process, such as tabletting, briquetting, or extrusion, preferably tabletting. Suitable equipment includes a standard single stroke or a rotary press (such as Courtoy®, Korch®, Manesty®, or Bonals®). As used herein, the term "non-particulate detergent product" includes physical shapes such as tablets, blocks, bars and the like.

Coating for non-particulate detergent product

In one embodiment, the tablets are coated with a coating in order to provide mechanical strength and shock and chip resistance to the compressed tablet core. The tablets are coated with a coating that is substantially insoluble in water so that the tablet does not absorb moisture, or absorbs moisture at only a very slow rate. The coating is strong so that moderate mechanical shocks to which the tablets are subjected during handling, packing and shipping result in no more than very low levels of breakage or attrition. Further, the coating is preferably brittle so that the tablet breaks up when subjected to stronger mechanical shock. Furthermore it is advantageous if the coating material is dissolved under alkaline conditions, or is readily emulsified by surfactants. This avoids the deposition of undissolved particles or lumps of coating material on the laundry load. This may be important when the coating material is completely insoluble (for example less than 1 g/l) in water.
As defined herein "substantially insoluble" means having a very low solubility in water. This should be understood to mean having a solubility in water at 25°C of less than 20 g/L, preferably less than 5 g/l, and more preferably less than 1 g/l. Water solubility is measured following the test protocol of ASTM E1148-87 entitled, "Standard Test Method for Measurements of Aqueous Solubility".
Suitable coating materials are fatty acids, adipic acid and C8-C13 dicarboxylic acids, fatty alcohols, diols, esters and ethers. Preferred fatty acids are those having a carbon chain length of from C12 to C22 and most preferably from C18 to C22. Preferred dicarboxylic acids are adipic acid (C6), suberic acid (C8), azelaic acid (C9), sebacic acid (C10), undecanedioic acid (C11), dodecanedioic acid (C12) and tridecanedioic acid (C13). Preferred fatty alcohols are those having a carbon chain length of from C12 to C22 and most preferably from C14 to C18. Preferred diols are 1,2-octadecanediol and 1,2-hexadecanediol. Preferred esters are tristearin. tripalmitin, methylbehenate, ethylstearate. Preferred ethers are diethyleneglycol mono hexadecylether, diethyleneglycol mono octadecylether. diethyleneglycol mono tetradecytether, phenylether, ethyl naphtyl ether, 2 methoxynaphtalene, beta naphtyl methyl ether and glycerol monooctadecylether. Other preferred coating materials include dimethyl 2,2 propanol. 2 hexadecanol. 2 octadecanone, 2 hexadecanone, 2, 15 hexadecanedione and 2 hydroxybenzyl alcohol. The coating is a hydrophobic material having a melting point preferably of from 40 °C to 180 °C.
In the preferred embodiment, the coating can be applied in a number of ways. Two preferred coating methods are a) coating with a molten material and b) coating with a solution of the material. In a), the coating material is applied at a temperature above its melting point, and solidifies on the tablet. In b), the coating is applied as a solution, the solvent being dried to leave a coherent coating. The substantially insoluble material can be applied to the tablet by, for example, spraying or dipping. Normally when the molten material is sprayed on to the tablet, it will rapidly solidify to form a coherent coating. When tablets are dipped into the molten material and then removed, the rapid cooling again causes rapid solidification of the coating material. Clearly substantially insoluble materials having a melting point below 40 °C are not sufficiently solid at ambient temperatures and it has been found that materials having a melting point above 180°C are not practicable to use. Preferably, the materials melt in the range from 60°C to 160 °C, more preferably from 70 °C to 120 °C.
By "melting point" is meant the temperature at which the material when heated slowly in, for example, a capillary tube becomes a clear liquid. For most purposes, the coating forms from 1% to 10%, preferably from 1.5% to 5%. of the tablet weight.

Addition of flow aids

In one embodiment. the process includes adding a flow aid to the particulate detergent composition in a range of from 0.1% to 25% by weight of the particulate detergent composition before compaction.
As used herein, the term "flow aids" means any material capable of being deposited on to the surface of detergent particles so as to reduce the stickiness of the detergent particles and allow them to flow freely. Flow aids could include porous carrier particles selected from the group consisting of amorphous silicates, crystalline nonlayer silicates, layer silicates, calcium carbonates, calcium/sodium carbonate double salts, sodium carbonates, clays, zeolites, sodalites, alkali metal phosphates, macroporous zeolites, chitin microbeads, carboxyalkylcelluloses, carboxyalkylstarches, cyclodextrins, porous starches and mixtures thereof.
The preferred flow aids are zeolite A, zeolite X, zeolite Y. zeolite P, zeolite MAP and mixtures thereof. The term "zeolite" used herein refers to a crystalline aluminosilicate material. The structural formula of a zeolite is based on the crystal unit cell, the smallest unit of structure represented by Mm/n[(AlO2)m(SiO2)y]•xH2O where n is the valence of the cation M, x is the number of water molecules per unit cell, m and y are the total number of tetrahedra per unit cell, and y/m is 1 to 100. Most preferably, y/m is 1 to 5. The cation M can be Group IA and Group IIA elements, such as sodium, potassium, magnesium, and calcium.
In the preferred embodiment of the present invention, the flow aid is added in an amount in a range, desirably, from 0.1% to 25% by weight of the particulate detergent, more desirably from 1% to 15% by weight, preferably from 1% to 10% by weight, and most preferably in an amount of 5% by weight. It is undesirable to add more than 25% by weight of the flow aid because too excessive a force would be needed to make the detergent particles to stick together and stay in a particulate form. Flow aid addition in an amount less than 0.1% by weight is also undesirable because little or no reduction in the stickiness of the detergent particles would occur. which upon compression into a particulate form would cause the resultant detergent tablet to not disintegrate readily when placed in water in a washing machine.
In one embodiment, the flow aids have a perfume adsorbed on their surface before being deposited on the detergent particles. Preferably, the flow aids are zeolites preferably containing less than 20% desorbable water, more preferably less than 8% desorbable water, and most preferably less than 5% desorbable water. Such materials may be obtained by first activating/dehydrating by heating to 150 to 350°C, optionally with reduced pressure (from 0.1 Pa (0.001 Torr) to 2.7 kPa (20 Torr). After activation, the perfume is slowly and thoroughly mixed with the activated zeolite and, optionally, heated to 60°C for up to 2 hours to accelerate absorption equilibrium within the zeolite particles. The perfume/zeolite mixture is then cooled to room temperature and is in the form of a free-flowing powder. The term "perfume" is used to indicate any odoriferous material which is subsequently released into the aqueous bath and/or onto fabrics contacted therewith. The perfume will most often be liquid at ambient temperatures. A wide variety of chemicals are known for perfume uses, including materials such as aldehydes, ketones and esters. More commonly, naturally occurring plant and animal oils and exudates comprising complex mixtures of various chemical components are known for use as perfumes. The perfumes herein can be relatively simple in their compositions or can comprise highly sophisticated complex mixtures of natural and synthetic chemical components, all chosen to provide any desired odor. Typical perfumes can comprise, for example, woody/earthy bases containing exotic materials such as sandalwood, civet and patchouli oil. The perfumes can be of a light floral fragrance, e.g., rose extract, violet extract, and lilac. The perfumes can also be formulated to provide desirable fruity odors, e.g., lime, lemon, and orange. Any chemically compatible material which exudes a pleasant or otherwise desirable odor can be used in the perfumed compositions herein. Perfumes also include pro-fragrances such as acetal pro-fragrances, ketal pro-fragrances, ester pro-fragrances (e.g., digeranyl succinate), hydrolyzable inorganic-organic pro-fragrances, and mixtures thereof. These pro-fragrances may release the perfume material as a result of simple hydrolysis, or may be pH-change-triggered pro-fragrances (e.g., pH drop) or may be enzymatically releasable pro-fragrances.
In the preferred embodiment, the amount of perfume adsorbed on the carrier material, such as zeolite for example, is preferably in the range of 0.1% to 50% by weight, more preferably in the range of 0.5% to 25% by weight, and most preferably in the range of 1% to 15% by weight of zeolite powder.

Compaction of particulate detergent to form non-particulate detergent product

In the preferred embodiment, the process still further includes the step of compacting the particulate detergent composition having at least 10% reduced porosity by applying a pressure in an amount sufficient to form the water-dispersible, non-particulate detergent product having a density of at least 1000 g/l. It is desirable to form a detergent tablet that has a density of at least 1000 g/l so that the tablet will sink in water. If the density of the detergent tablet is less than 1000 g/l, the tablet will float when placed in the water in a washing machine and this will detrimentally reduce the dissolution rate of the tablet in the water. It is desirable to apply at least that much pressure as is sufficient to compress the particulate detergent material to form a tablet having a density of at least 1000 g/l. Too little a pressure will result in a compressed tablet with a density less than 1000 g/l.

EXAMPLE A

Detergent tablets are formed from detergent particles having at least 10% reduced porosity before such particles are compressed into a tablet form, according to the following composition:

Ingredients % by weight

Detergent particles 95.00

polyethylene glycol (MW=200) 5.00

Total 100.00

The detergent particles have the following composition:

Particulate detergent Ingredients	% by weight
C _12-16 linear alkylbenzene sulfonate	8.80
C _14-15 alkyl sulfate/C _14-15 alkyl ethoxy sulfate	8.31
C _12-13 alkyl ethoxylate	1.76
polyacrylate (MW=4500)	2.40
polyethylene glycol (MW=4000)	0.96
sodium sulfate	8.40
aluminosilicate	21.28
sodium carbonate	16.80
protease enzyme	0.32
sodium perborate monohydrate	2.08
lipase enzyme	0.17
cellulase enzyme	0.08
NOBS extrudate	4.80
citric acid monohydrate	2.25
sodium bicarbonate	2.75
sodium acetate	15.00
free water	1.60
other minor ingredients (perfume etc.)	2.24
Total	100.00

The detergent tablet formed is coated with a coating according to the following composition:

Ingredient % by weight

Detergent tablet having PEG 91.10

Coating:

dodecanedioc acid 8.00

carboxymethyl cellulose 0.90

Total 100.00
Optionally, a flow aid (zeolite) is also added to the particulate detergent composition in about 5% by weight of the detergent and mixed by one of various methods. such as agitation for example.
The tablets are formed by compressing the tablet ingredients in a cylindrical die having a diameter of 55 mm using a laboratory press having a trade name Carver Model 3912, to form a tablet having a height of 20 mm. The formed tablets were then coated with the protective coating by dipping the tablet into a molten bath of the coating for about 3 seconds. The molten coating bath is maintained at a temperature of about 145 degrees centigrade.
The term "NOBS extrudate" as used herein. is an acronym for the chemical sodium nonanoyloxybenzene sulfonate, commercially available from Eastman Chemicals, Inc. The carboxymethyl cellulose used in the above example is commercially available from Metsa-Serla and sold under the trade name. Nymcel ZSB-16(TM).

Test for determining dispersibility in water

The following method is used to measure the rate of dispersion (ROD) of a detergent tablet expressed as percentage residue remaining after "t" minutes, where "t" is 3, 5 and 10 minutes. The equipment used includes a 5000 ml glass beaker, a stopwatch with alarm, an electrical stirrer with variable speed IKA RW 20 DZM or equivalent, a cage made of perforated metal gauze (diameter 52 mm, height 40 mm having 16 apertures each of about 2.5 mm square) and a weigh scale with accuracy of 0.1 grams.
The method includes the following steps: The beaker is filled with 4000 ml (+/-50 ml) of distilled water at 20 °C (+/- 1 °C). The cage tester is mounted in the electrical stirrer. A tablet with a known weight is placed in the cage and the cage is connected to the stirrer. The cage is submerged in the water with the cage, suspended about half way down the beaker and the stirrer is started at a fixed speed of 80 rpm. The stopwatch is started. The stirrer is stopped after 3 minutes. The cage is lifted out of the water and the tablet residue remaining in the cage is weighed. The % residue is calculated with the following equation: % residue = Tablet weight after "t" minutesInitial tablet weight x 100 The remaining tablet is placed back in the cage and the process is repeated for an additional 2 and 5 minutes to give yield data for tablet dispersion after 3, 5 and 10 minutes.
As used herein, the term "dispersibility in water" is defined as a measure of the % residue, as calculated above, after 3 minutes. In other words, for example, a detergent tablet which has 5% by weight less residue than another detergent tablet would be deemed to have 5% greater dispersibility in water.
It is unexpectedly and surprisingly discovered that the non-particulate detergent product, e.g., a detergent tablet, has at least about 5% greater dispersability in water as compared to another non-particulate detergent product having a density of at least about 1000 g/l but not having nonionic liquid added to the detergent composition according to this invention.
The rapidly water dispersible non particulate detergent product of the present invention, can be used in a method of laundering fabric materials in a washing machine. It includes the steps of providing a flexible porous bag adapted for receiving a non-particulate detergent product, providing a non-particulate detergent product, placing the non-particulate detergent product within the flexible porous bag, and placing the flexible porous bag containing the detergent product in the washing machine with the fabric materials to be washed.
The flexible porous bag is permeable to water and to the washing medium and is thus adapted for permitting entry of an aqueous washing medium through the bag, thereby dissolving the non-particulate detergent product placed therein, into the aqueous washing medium, and releasing a resultant wash solution from inside of the bag to outside of the bag and into the aqueous wash medium during a wash cycle.
The flexible porous bag is made of a material capable of retaining the non-particulate detergent product without allowing it to pass through until the detergent product has dissolved in the washing medium. The bag is also made of a material capable of withstanding the temperatures of washing laundry in a washing machine. The process of the invention may be applied not only to non-particulate detergents but also to any non-particulate product which is active during washing, such as, for example, bleaching agents, such as agents releasing chlorine or active oxygen (peroxygen compounds), bleaching catalysts. bleaching activators, bactericides. foam regulators, whiteners, agents preventing the re-deposition of soil, enzymes, softeners, agents capable of removing grease stains or other constituents having no direct effect on the soiling but capable of taking part in the laundry washing process.
The flexible bag may be made from any material which offers a sufficient resistance to water, such as a woven or non-woven material produced from natural or synthetic fibers. For example, the bag is formed of pure cotton either in the form of a fabric with a mesh opening of less than 0.5 mm or in the form of a non-woven article with openings having a size in a range of from 0.5 mm to 0.8 mm.
Accordingly, having thus described the invention in detail, it will be obvious to those skilled in the art that various changes may be made without departing from the scope of the invention and the invention is not to be considered limited to what is described in the specification.

Claims

A process for producing a water-dispersible. non-particulate detergent product from low density detergent particles having a bulk density in a range of from 400 g/l to 850 g/l, characterized by the steps of:

(a) providing low density detergent particles having an intra-particle porosity, as measured by a Mercury Porosimeter, in a range of from 5% to 90% by volume;

(b) adding a liquid to said low density detergent particles in an amount sufficient to reduce said intra-particle porosity, as measured by a Mercury Porosimeter, by at least 10%; and

(c) compacting said low density detergent particles having said reduced intra-particle porosity, by applying a pressure in an amount sufficient to form said water-dispersible, non-particulate detergent product having a density of at least 1000 g/l.
The process of claim 1 wherein said low density detergent particles of step (a) have an intra-particle porosity in a range of from 10% to 80% by volume.
The process of any of claims 1-2 wherein said low density detergent particles of step (a) have a bulk density in a range of from 600 g/l to 850 g/l.
The process of any of claims 1-3 wherein said liquid is a nonionic surfactant and is added to said low density detergent particles in an amount sufficient to reduce said intra-particle porosity by at least 20%.
The process of any of claims 1-4 wherein said liquid is added in an amount in a range of from 0.1% to 10% by weight of said low density detergent particles.
The process of any of claims 1-5 wherein said liquid is selected from the group consisting of nonionic surfactants, anionic surfactants, water, polyethylene glycol, and mixtures thereof
The process of any of claims 1-6 wherein said liquid is a nonionic surfactant.
The process of any of claims 1-7 wherein said liquid is polyethylene glycol having a molecular weight less than 1000.
The process of any of claims 1-8 wherein said water-dispersible, non-particulate detergent product has at least 5% greater dispersability in water as compared to a non-particulate detergent product having a density of at least 1000 g/l but not having said liquid added to said low density particulate detergent composition per step (b).
A process according to claims 1 to 9 for producing a water-dispersible, non-particulate detergent product from a low density detergent composition, said process comprising the steps of:

(a) providing spray dried detergent granules having a bulk density less than 650 g/l;

(b) providing agglomerated detergent particles having a bulk density in a range of from 700 g/l to 900 g/l;

(c) mixing said spray dried detergent granules and said agglomerated detergent particles to form a low density detergent composition, wherein said spray dried detergent granules are present in a range of from 40% to 80% by weight of said low density detergent composition and said agglomerated detergent particles are present in a range of from 20% to 60% by weight of said low density detergent composition;

(d) adding a liquid to said low density detergent composition in an amount sufficient to reduce intra-particle porosity by at least 10%; and

(e) compacting said low density detergent composition having said reduced intra-particle porosity, by applying a pressure in an amount sufficient to form said water-dispersible, non-particulate detergent product having a density of at least 1000 g/l.