Classifications

• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D3/00—Other compounding ingredients of detergent compositions covered in group C11D1/00
  • C11D3/16—Organic compounds
  • C11D3/37—Polymers
  • C11D3/3746—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • C11D3/3757—(Co)polymerised carboxylic acids, -anhydrides, -esters in solid and liquid compositions
  • C11D3/3761—(Co)polymerised carboxylic acids, -anhydrides, -esters in solid and liquid compositions in solid compositions
• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D17/00—Detergent materials or soaps characterised by their shape or physical properties
  • C11D17/0047—Detergents in the form of bars or tablets
  • C11D17/0065—Solid detergents containing builders
  • C11D17/0073—Tablets
• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D3/00—Other compounding ingredients of detergent compositions covered in group C11D1/00
  • C11D3/16—Organic compounds
  • C11D3/20—Organic compounds containing oxygen
  • C11D3/22—Carbohydrates or derivatives thereof
  • C11D3/222—Natural or synthetic polysaccharides, e.g. cellulose, starch, gum, alginic acid or cyclodextrin
• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D3/00—Other compounding ingredients of detergent compositions covered in group C11D1/00
  • C11D3/16—Organic compounds
  • C11D3/20—Organic compounds containing oxygen
  • C11D3/22—Carbohydrates or derivatives thereof
  • C11D3/222—Natural or synthetic polysaccharides, e.g. cellulose, starch, gum, alginic acid or cyclodextrin
  • C11D3/225—Natural or synthetic polysaccharides, e.g. cellulose, starch, gum, alginic acid or cyclodextrin etherified, e.g. CMC
• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D3/00—Other compounding ingredients of detergent compositions covered in group C11D1/00
  • C11D3/16—Organic compounds
  • C11D3/37—Polymers
  • C11D3/3746—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • C11D3/3769—(Co)polymerised monomers containing nitrogen, e.g. carbonamides, nitriles or amines
  • C11D3/3776—Heterocyclic compounds, e.g. lactam

Definitions

• This invention relates to cleaning compositions in the form of tablets. These tablets are intended to disintegrate when placed in water and thus are intended to be consumed in a single use.
• the tablets may be suitable for use in machine dishwashing, the washing of fabrics or other cleaning tasks.
• compositions in tablet form and intended for fabric washing have been described in a number of patent documents including, for example EP-A-711827, WO-98/42817 and WO-99/20730 (Unilever) and are now sold commercially. Tablets of composition suitable for machine dishwashing have been disclosed in EP-A-318204 and US-A- 5691293 and are sold commercially. Tablets have several advantages over powdered products : they do not require measuring and are thus easier to handle and dispense into the washload, and they are more compact, hence facilitating more economical storage .
• Tablets of a cleaning composition are generally made by compressing or compacting a composition in particulate form. Although it is desirable that tablets have adequate strength when dry, yet disperse and dissolve quickly when brought into contact with water, it can be difficult to obtain both properties together. Tablets formed using a low compaction pressure tend to crumble and disintegrate on handling and packing; while more forcefully compacted tablets may be sufficiently cohesive but then fail to disintegrate or disperse to an adequate extent in the wash. Tableting will often be carried out with enough pressure to achieve a compromise between these desirable but antagonistic properties. However, it remains desirable to improve one or other of these properties without detriment to the other so as to improve the overall compromise between them.
• a tablet contains organic surfactant, this can function as a binder, plasticising the tablet. However, it can also retard disintegration of the tablet by forming a viscous gel when the tablet comes into contact with water. Thus, the presence of surfactant can make it more difficult to achieve both good strength and speed of disintegration: the problem has proved especially acute with tablets formed by compressing powders containing surfactant and built with insoluble detergency builder such as sodium aluminosilicate (zeolite) .
• insoluble detergency builder such as sodium aluminosilicate (zeolite)
• the particles of a detergent composition used for compaction into tablets should have their size confined within a limited range of particle size. Fine particles smaller than 200 m are excluded.
• the bulk of the composition should be particles with sizes confined within a size range spanning no more than 700 ⁇ m and located within a broader range from 200 m to 2000 m.
• a binder material which functions as a disintegrant can advantageously be used by applying it to the surface of other particles. Results set out in the Examples of this document show that in the absence of such a binder, faster dissolution of tablets occurs when the particle sizes in the composition are restricted to a narrow range of small sizes - 250 to 500 m.
• binder material cross-linked polyvinyl pyrrolidone
• WO-A-98/40463 teaches the use of a cellulosic swelling disintegrant in the form of granules with a particle size in a range from 300 ⁇ m to 1600.m.
• the swelling disintegrant particle size was such that more than 90% was in a size range from 200 to 2000 i um. The same was true of the remainder of the detergent composition.
• a water-swellable but insoluble disintegrant should preferably have a particle size of at least 500 m.
• 3% of disintegrant sieved to a size range of 800- 1400 ⁇ m displayed a tablet strength and speed of disintegration which were slightly superior to those with 5% of the same disintegrant sieved to a size range of 470- 800 m.
• a detergent tablet in which a discrete region or the entire tablet consists of compacted particulate detergent composition including organic surfactant, detergency builder and other constituents, wherein the composition of the tablet or a discrete region thereof consists of
• disintegrant particles from 1% to 15% by weight of disintegrant particles containing water-swellable, water-insoluble disintegrant material (ii) a balance from 85 to 99% by weight of further component particles characterised in that the particle sizes and size distributions are such that: the mean particle size of the disintegrant particles (i)is not more than 1.4 times, better not more than 1.3 times the mean particle size of the further component particles (ii) ; and at least 90% by weight of the further component particles (ii) have a size greater than 350 m.
• Tablets made from a composition in accordance with the above requirements exhibit faster disintegration in water, whilst retaining their strength, compared to tablets in which the particle size distributions fall outside those defined above .
• the invention is employed in a region of a tablet rather than the whole of the tablet, that region will have the advantage of faster disintegration while retaining strength.
• a tablet of the present invention may be either homogeneous or heterogeneous.
• the term “homogeneous” is used to mean a tablet produced by compaction of a single particulate composition, but does not imply that all the particles of that composition will be of identical composition.
• the term “heterogeneous” is used to mean a tablet consisting of a plurality of discrete regions, for example layers, inserts or coatings, each derived by compaction from a particulate composition.
• each discrete region of the tablet will preferably have a mass of at least 5gm.
• Particle Sizes are the particle sizes of the constituents of the particulate detergent composition before compaction to form detergent tablets.
• At least 90% by weight of the disintegrant particles (i) also have a size greater than 350 m.
• the mean particle size of the disintegrant particles (i) is not more than 1.4 times, preferably not greater than 1.3 or even 1.2 times, the mean particle size of the further component particles (ii) . Possibly the mean particle size of the disintegrant particles (i) is not greater than the mean particle size of the further component particles (ii) . It is also preferred that the mean particle size of the disintegrant particles (i) is at least 0.5 better at least 5 0.7 times the mean particle size of the further component particles (ii) .
• the mean particle size of the further component particles (ii) is in a range of 500 to 10 1200 ⁇ m.
• the preferred particle size distribution of the further component particles (ii) about the mean particle size can be defined in relation to upper and lower thresholds, XT J
• 90% by weight of the particles have size between the upper and lower thresholds, no more than 5% by weight of the particles have a size less than the lower threshold (X L ) and no more than 5% by weight of the particles have a size
• the lower threshold (X L ) is at least 350 ⁇ m and the upper threshold (Xu) is less than 1500 ⁇ m or 2000 m. Even more preferred is
• adjustable parameters in agglomeration processes include the liquid to solids ratio in the mixture which is being granulated, operating temperature and residence time in the mixer which is carrying out granulation.
• Particle size range can be controlled by removing oversized and undersized particles. Oversized particles are usually removed by a sieving operation, and may then be milled and recycled to an earlier stage of the manufacturing process.
• Undersize particles can also be removed by sieving, or if the manufacturing process employs a fluidised bed, they can be entrained in the gas stream from the bed.
• Mean particle size refers to the value d 50 , which is the aperture of a (theoretical) sieve through which 50 weight % of the powder passes (see Particle Size Measurement by T Allen, 2 nd Edition, Chapman & Hall, 1975) .
• a number of water-insoluble, water-swellable materials are known to be useful as tablet disintegrants, in particular for pharmaceutical tablets. Discussion of such materials is found in "Drug Development and Industrial Pharmacy", Volume 6, pages 511-536 (1980) .
• such materials may be included in an amount of 0.1 or 0.5% to 10% by weight of the tablet or discrete region thereof. Such materials may be mixed with each other, or mixed with other materials as carriers. If these water-swellable materials are included as part of disintegrant particles, these particles may be present in an amount of 1 to 10% by weight of the tablet or region thereof .
• Such materials are mostly polymeric in nature and many of them are of natural origin.
• Such disintegrants include starches, for example, maize, rice and potato starches and starch derivatives, such as PrimojelTM or ExplotabTM, both of which are sodium starch glycolate also known as sodium carboxymethyl starch; celluloses, for example, Arbocel ® -B and Arbocel®-BC (beech cellulose) , Arbocel®-BE (beech- sulphite cellulose) , Arbocel®-B-SCH (cotton cellulose) , Arbocel®-FIC (pine cellulose) as well as further Arbocel® types from Rettenmaier and cellulose derivatives, for example CourloseTM and NymcelTM, sodium carboxymethyl cellulose, Ac-di-SolTM cross-linked modified cellulose, microcrystalline cellulosic fibres cross-linked cellulose; and various synthetic organic polymers.
• Cellulose-containing fibrous materials originating from timber may be compacted wood pulps.
• So-called mechanical pulps generally incorporate lignin as well as cellulose whereas chemical pulps generally contain cellulose but little of the original lignin remains.
• Pulp obtained by a mixture of chemical and mechanical methods may retain some but not all of the original lignin.
• Another parameter which characterises swellable materials is the force which they exert if they are allowed to take up water whilst confined within an enclosure.
• EP-A-333104 An apparatus for measuring both of these parameters is described in EP-A-333104.
• a sample of material is pressed against a sintered glass disc.
• the force by which it is pressed against the disc is measured by means of a load cell .
• the sample is allowed to take up water or aqueous solution through the sintered glass disc.
• the supply for this water or aqueous solution is a reservoir which has been placed on a balance.
• the force on the load cell and the weight lost from the reservoir are monitored over a period of time.
• materials and particles which swell on contact with water are effective as disintegrants if thee is a rapid development of force when they come into contact with water.
• the apparatus consists of a cylinder (10) with internal diameter 25mm and a length of 20mm. This cylinder is perforated by a ring of holes (12) adjacent one end. There are 36 of these holes, of 1mm diameter, with centres 2.5mm from the end of the cylinder.
• This end of the cylinder is glued to the base of a glass container (14) of internal diameter 73mm.
• a plunger (18) of the Instron machine is moved into the upper set of the cylinder, over this powder bed.
• the plunger is applied to the top of the powder bed (16) with a force of 1 Newton .
• the significant parameter is the maximum slope of a graph of expansion force against time.
• Measurement of swelling can be recorded with the same apparatus.
• the plunger is again applied to the top of a bed of the dry powder, and pressed against it with a force of 1 Newton. 50ml of water is poured in as before.
• the Instron machine is programmed to allow expansion of the bed of powder, while maintaining a force on it of 1 Newton. Displacement of the plunger is recorded.
• Disintegrant particles may consist of a carrier material which absorbs some water. And may swell on initial contact with water mixed with a minor proportion of another material which swells more strongly than the carrier material on contact with water. It may take up more water than the carrier material, or swell more rapidly or both. The proportions may be from 75% or 90% up to 99.9% of the carrier material and from 0.1 up to 10%, of the more strongly swelling material.
• a water-soluble synthetic organic polymer is present as a binder.
• the strongly swelling material if tested, by itself, has ability to absorb at least twice possibly at least 2.5 or 3 times its own volume of water and has a development of expansion force which exceeds 1.5 Newton/second.
• the more strongly swelling material may come from a category referred to as a super-disintegrant .
• Such super disintegrants tend to be cross-linked synthetic or natural polymers and include cross-linked forms of carboxymethyl cellulose, cellulose, starch, polyvinylpyrrolidone and polyacrylate .
• the carrier materials are preferably selected from compounds which contain hydroxy groups .
• a carrier material may itself be a water-insoluble, and somewhat water-swellable material. Such materials include starches, for example, maize, rice and potato starches, celluloses, microcrystalline cellulosic fibres and some synthetic organic polymers.
• Disintegrant particles may also contain up to 15% or 20% by weight of a water-soluble polymer which acts as a binder, e.g. polyethylene glycol .
• a super-disintegrant may take up more than twice its own volume of water, while a carrier for it takes up less water by volume than the super-disintegrant.
• Such disintegrant particles may be made by mixing the swellable disintegrant with the carrier material, then compacting the mixture, and if necessary comminuting the compacted mixture into disintegrant particles.
• Preferably these have a particle size in a range from 250 to 1000 microns.
• Suitable apparatus - a roller compactor - has a feed screw which delivers the mixture to the nip of the rollers. The speed of the feed screw, and hence the amount of material delivered to the nip of the roller should be high enough to force an unbroken stream of material through the rollers, but not so high that the material is converted into a dough.
• the sheet material which issues from the rollers is next broken up and milled to the required particle size.
• roller compactor and milling machinery Manufacturers of both roller compactor and milling machinery include Hosakawa Beper located at Heilbronn, Germany, Alexanderwerk located at Remetz, Germany and Fitzpatrick located at Elmhurst, USA.
• compositions which are compacted to form tablets of this invention, or discrete regions thereof contain one or more organic detergent surfactants.
• these preferably provide from 5 to 40% by weight of the composition of the tablet or region thereof, more preferably from 8 or 9% by weight of the composition up to 30% or 35% by weight. If the tablet is composed of more than one discrete region, then these preferred amounts of surfactant may apply to the tablet as a whole.
• This organic surfactant forms part of the further component particles (ii) which make up the balance if the composition.
• Surfactant may be anionic (soap or non-soap) , cationic, zwitterionic, amphoteric, nonionic or a combination of these .
• anionic surfactant may be present in an amount from 0.5 to 40% by weight, preferably from 2% or 4% up to 30% or 35% by weight of the tablet or region thereof .
• organic surfactant is likely to constitute from 0.5 to 8%, more likely from 0.5 to 4.5% of the composition of the tablet or region thereof and is likely to consist of nonionic surfactant, either alone or in a mixture with anionic surfactant .
• Synthetic (i.e. non-soap) anionic surfactants are well known to those skilled in the art. Examples include alkylbenzene sulphonates, particularly sodium linear alkylbenzene sulphonates having an alkyl chain length of C ⁇ -Cis; olefin sulphonates; alkane sulphonates; dialkyl sulphosuccinates; and fatty acid ester sulphonates.
• R0S0 3 " M + in which R is an alkyl or alkenyl chain of 8 to 18 carbon atoms especially 10 to 14 carbon atoms and M + is a solubilising cation, is commercially significant as an anionic surfactant .
• R is linear alkyl of 8 to 15 carbon atoms and M + is a solubilising cation, especially sodium, is also a commercially significant anionic surfactant.
• anionic surfactant such linear alkyl benzene sulphonate or primary alkyl sulphate of the formula above, or a mixture thereof will be the desired anionic surfactant and may provide 75 to 100 wt% of any anionic non-soap surfactant in the composition.
• the amount of non-soap anionic surfactant lies in a range from 5 to 20 or 25 wt% of the tablet or region thereof.
• soaps of fatty acids are preferably sodium soaps derived from naturally occurring fatty acids, for example, the fatty acids from coconut oil, beef tallow, sunflower or hardened rapeseed oil .
• Suitable nonionic surfactant compounds which may be used include in particular the reaction products of compounds having a hydrophobic group and a reactive hydrogen atom, for example, aliphatic alcohols, acids, amides or alkyl phenols with alkylene oxides, especially ethylene oxide.
• nonionic surfactant compounds are alkyl (C 8 . 22 ) phenol-ethylene oxide condensates, the condensation products of linear or branched aliphatic C 8 - 0 primary or secondary alcohols with ethylene oxide, and products made by condensation of ethylene oxide with the reaction products of propylene oxide and ethylene-diamine .
• the primary and secondary alcohol ethoxylates especially the C 9 _ 1 and C1 2 - 1 5 primary and secondary alcohols ethoxylated with an average of from 5 to
• the amount of nonionic surfactant lies in a range from 4 to 40%, better 4 or 5 to
• nonionic surfactants are liquids. These may be absorbed onto particles of the composition forming part of the other particles (ii) , prior to compaction into tablets.
• Amphoteric surfactants which may be used jointly with anionic or nonionic surfactants or both include amphopropionates of the formula:
• RCO is a acyl group of 8 to 18 carbon atoms, especially coconut acyl.
• amphoteric surfactants also includes amine oxides and also zwitterionic surfactants, notably betaines of the general formula
• R 4 is an aliphatic hydrocarbon chain which contains 7 to 17 carbon atoms
• R 2 and R 3 are independently hydrogen, alkyl of 1 to 4 carbon atoms or hydroxyalkyl of 1 to 4 carbon atoms such as CH 2 0H
• Y is CH 2 or of the form CONHCH 2 CH 2 CH 2 (amidopropyl betaine)
• Z is either a COO "
• amphoteric surfactant is amine oxide of the formula
• R x is C ⁇ 0 to C 20 alkyl or alkenyl
• R 2 , R 3 and R 4 are each hydrogen or Ci to C 4 alkyl, while n is from 1 to 5.
• Cationic surfactants may possibly be used. These frequently have a quaternised nitrogen atom in a polar head group and an attached hydrocarbon group of sufficient length to be hydrophobic .
• a general formula for one category of cationic surfactants is
• each R independently denotes an alkyl group or hydroxyalkyl group of 1 to 3 carbon atoms and R h denotes an aromatic, aliphatic or mixed aromatic and aliphatic group of 6 to 24 carbon atoms, preferably an alkyl or alkenyl group of 8 to 22 carbon atoms and X " is a counterion.
• the amount of amphoteric surfactant, if any, may possibly be from 3% to 20 or 30% by weight of the tablet or region of a tablet; the amount of cationic surfactant, if any, may possibly be from 1% to 10 or 20% by weight of the tablet or region of a tablet.
• composition which is compacted to form a tablet or a discrete tablet regions also contains a detergency builder which serves to remove or sequester calcium and/or magnesium ions in the water.
• the amount of it is likely to lie in a broad range from 10 better 15 wt% up to 80% of the tablet composition.
• the amount is more likely to be from 15 to 70%, more usually 15 to 60% by weight of the tablet.
• Detergency builders may be provided wholly by water soluble materials, or may be provided in large part or even entirely by water-insoluble material with water-softening properties .
• Alkali metal aluminosilicates are strongly favoured as environmentally acceptable detergency builders for fabric washing, and are preferred in this invention.
• Alkali metal (preferably sodium) aluminosilicates may be either crystalline or amorphous or mixtures thereof, having the general formula : 0 . 8 - 1 . 5 Na 2 O .Al 2 0 3 . 0 . 8 - 6 Si0 2 . xH 2 0
• These materials contain some bound water (indicated as xH 2 0) and are required to have a calcium ion exchange capacity of at least 50 mg CaO/g.
• the preferred sodium aluminosilicates contain 1.5-3.5 Si0 units (in the formula above) . Both the amorphous and the crystalline materials can be prepared readily by reaction between sodium silicate and sodium aluminate, as amply described in the literature.
• Suitable crystalline sodium aluminosilicate ion-exchange materials are described, for example, in GB 1429143 (Procter & Gamble) .
• the preferred sodium aluminosilicates of this type are the well known commercially available zeolites A and X, the newer zeolite P described and claimed in EP 384070 (Unilever) and mixtures thereof.
• This form of zeolite P is also referred to as "zeolite MAP".
• zeolite A24 One commercial form of it is denoted "zeolite A24".
• a detergency builder could be a layered sodium silicate as described in US 4664839.
• NaSKS-6 is the trademark for a crystalline layered silicate marketed by Hoechst (commonly abbreviated as "SKS-6") .
• KS-6 has the delta-Na 2 Si0 5 morphology form of layered silicate. It can be prepared by methods such as described in DE-A-3,417, 649 and DE-A-3, 742, 043.
• layered silicates such as those having the general formula NaMSi x ⁇ 2 X+ ⁇ .yH 2 0 wherein M is sodium or hydrogen, x is a number from 1.9 to 4, preferably 2, and y is a number from 0 to 20, preferably 0 can be used.
• the less preferred category of water-soluble phosphorus- containing inorganic softeners includes the alkali-metal orthophosphates, metaphosphates, pyrophosphates and polyphosphates .
• Specific examples of inorganic phosphate detergency builders include sodium and potassium tripolyphosphates, orthophosphates and hexametaphosphates .
• Non-phosphorus water-soluble detergency builders may be organic or inorganic.
• Inorganics that may be present include alkali metal (generally sodium) carbonate; while organics include polycarboxylate polymers, such as polyacrylates, acrylic/maleic copolymers, and acrylic phosphonates, monomeric polycarboxylates such as citrates, gluconates, oxydisuccinates, glycerol mono- di- and trisuccinates, carboxymethyloxysuccinates, carboxymethyloxymalonates, dipicolinates and hydroxyethyliminodiacetates .
• alkali metal generally sodium
• organics include polycarboxylate polymers, such as polyacrylates, acrylic/maleic copolymers, and acrylic phosphonates, monomeric polycarboxylates such as citrates, gluconates, oxydisuccinates, glycerol mono- di- and trisuccinates, carboxymethyloxysuccinates, carboxymethyloxymalonates, dipicolinates and hydroxyethyliminodiacetates .
• Tablet compositions preferably include polycarboxylate polymers, more especially polyacrylates and acrylic/maleic copolymers which have some function as water-softening agents and also inhibit unwanted deposition onto fabric from the wash liquor.
• compositions according to the invention may contain a bleach system, which would form part of the further component particles (ii) .
• This preferably comprises one or more peroxy bleach compounds, for example, inorganic persalts or organic peroxyacids, which may be employed in conjunction with activators to improve bleaching action at low wash temperatures. If any peroxygen compound is present, the amount is likely to lie in a range from 10 to 85% by weight of the composition of the tablet or region thereof. If the tablet contains surfactant and detergency builder, the amount of peroxygen compound bleach is unlikely to exceed 25% of the composition of the tablet or region thereof.
• Preferred inorganic persalts are sodium perborate monohydrate and tetrahydrate, and sodium percarbonate, advantageously employed together with an activator.
• Bleach activators also referred to as bleach precursors
• Preferred examples include peracetic acid precursors, for example, tetraacetylethylene diamine (TAED) , now in widespread commercial use in conjunction with sodium perborate; and perbenzoic acid precursors .
• TAED tetraacetylethylene diamine
• the quaternary ammonium and phosphonium bleach activators disclosed in US 4751015 and US 4818426 (Lever Brothers Company) are also of interest.
• Another type of bleach activator which may be used, but which is not a bleach precursor is a transition metal catalyst as disclosed in EP-A-458397, EP-A-458398 and EP-A- 549272.
• a bleach system may also include a bleach stabiliser (heavy metal sequestrant) such as et ylenediamine tetramethylene phosphonate and diethylenetriamine pentamethylene phosphonate.
• a tablet or a region of a tablet may contain water-soluble particles to promote disintegration. These would be in addition to the water-swellable, water-insoluble particles (i) as required by this invention, and would form part of the further component particles (ii) . It may be preferred that such particles make up from 3%, better from 5% or 10% to 50% by weight of the composition of the tablet or region thereo .
• Such soluble particles typically contain at least 50% (of their own weight) of one or more materials which is other than soap or organic surfactant and which has a solubility in deionised water of at least 10 g/lOOg at 20°C.
• this water-soluble material is selected from either:
• sodium tripolyphosphate containing at least 50% of its own weight of the phase I anhydrous form, and which is partially hydrated so as to contain water of hydration in an amount which is at least 1% by weight of the sodium tripolyphosphate in the particles .
• these disintegration- promoting particles can also contain other forms of tripolyphosphate or other salts within the balance of their composition.
• the material in such water-soluble disintegration- promoting particles can function as a detergency builder, (as is the case with sodium tripolyphosphate) them of course it contributes to the total quantity of detergency builder in the tablet composition.
• the quantity of water-soluble disintegration-promoting particles may be from 10% up to 30 or 40% by weight of the tablet or region thereof.
• the quantity may possibly be from 12% up to 25 or 30% or more.
• a solubility of at least 50g/100g of deionised water at 20°C is an exceptionally high solubility: many materials which are classified as water soluble are less soluble than this. Materials of such high solubility may be used in amounts from 3%, possibly from 5% or 10% up to 30% by weight of the tablet.
• this highly water soluble material is incorporated as particles of the material in a substantially pure form (i.e. each such particle contains over 95% by weight of the material) .
• the said particles may contain material of such solubility in a mixture with other material, provided that material of the specified solubility provides at least 50% by weight of these particles.
• a preferred material is sodium acetate in a partially or fully hydrated form.
• the highly water-soluble material is a salt which dissolves in water in an ionised form. As such a salt dissolves it leads to a transient local increase in ionic strength which can assist disintegration of the tablet by preventing nonionic surfactant from swelling and inhibiting dissolution of other materials.
• the said particles which promote disintegration are particles which contain sodium tripolyphosphate with more than 50% (by weight of the particles) of the anhydrous phase I form, and which is partially hydrated so as to contain water of hydration in an amount which is at least 1% by weight of the sodium tripolyphosphate .
• Sodium tripolyphosphate is very well known as a sequestering builder in detergent compositions. It exists in a hydrated form and two crystalline anhydrous forms. These are the normal crystalline anhydrous form, known as phase II which is the low temperature form, and phase I which is stable at high temperature. The conversion of phase II to phase I proceeds fairly rapidly on heating above the transition temperature, which is about 420°C, but the reverse reaction is slow. Consequently phase I sodium tripolyphosphate is metastable at ambient temperature. A process for the manufacture of particles containing a high proportion of the phase I form of sodium tripolyphosphate by spray drying below 420°C is given in US-A-4536377.
• These particles should also contain sodium tripolyphosphate which is partially hydrated.
• the extent of hydration should be at least 1% by weight of the sodium tripolyphosphate in the particles. It may lie in a range from 1 to 4%, or it may be higher. Indeed fully hydrated sodium tripolyphosphate may be used to provide these particles .
• the remainder of the tablet composition used to form the tablet or region thereof may include additional sodium tripolyphosphate.
• This may be in any form, including sodium tripolyphosphate with a high content of the anhydrous phase II form-.
• Suitable material is commercially available. Suppliers include Rhone-Poulenc, France and Albright & Wilson, UK.
• Tablets of the invention may also contain one of the detergency enzymes well known in the art for their ability to degrade and aid in the removal of various soils and stains.
• Suitable enzymes include the various proteases, cellulases, lipases, amylases, and mixtures thereof, which are designed to remove a variety of soils and stains from fabrics.
• suitable proteases are Maxatase (Trade Mark), as supplied by Gist-Brocades N.V. , Delft, Holland, and Alcalase (Trade Mark) , and Savinase (Trade Mark) , as supplied by Novo Industri A/S, Copenhagen, Denmark.
• Detergency enzymes are commonly employed in the form of granules or marumes, optionally with a protective coating, in amount of from about 0.1% to about 3.0% by weight of the composition of the tablet or region thereof; and these granules or marumes present no problems with respect to compaction to form a tablet.
• the tablets of the invention may also contain a fluorescer (optical brightener) , for example, Tinopal (Trade Mark) DMS or Tinopal CBS available from Ciba-Geigy AG, Basel, Switzerland.
• Tinopal DMS is disodium 4,4'bis-(2- morpholino-4-anilino-s-triazin-6-ylamino) stilbene disulphonate
• Tinopal CBS is disodium 2 , 2 ' -bis- (phenyl- styryl) disulphonate.
• An antifoam material is advantageously included if organic surfactant is present, especially if a detergent tablet is primarily intended for use in front-loading drum-type automatic washing machines.
• Suitable antifoam materials are usually in granular form, such as those described in EP 266863A (Unilever) .
• Such antifoam granules typically comprise a mixture of silicone oil, petroleum jelly, hydrophobic silica and alkyl phosphate as antifoam active material, sorbed onto a porous absorbed water-soluble carbonate-based inorganic carrier material.
• Antifoam granules may be present in an amount up to 5% by weight of the composition of the tablet or region thereof.
• a tablet of the invention includes an amount of an alkali metal silicate, particularly sodium ortho-, meta- or disilicate.
• an alkali metal silicate particularly sodium ortho-, meta- or disilicate.
• a composition for fabric washing will generally not contain more than 15 wt% silicate.
• a tablet for machine dishwashing will frequently contain at least 20 wt% silicate.
• compositions which can optionally be employed in fabric washing detergent tablets of the invention include anti-redeposition agents such as sodium carboxymethylcellulose, straight-chain polyvinyl pyrrolidone and the cellulose ethers such as methyl cellulose and ethyl hydroxyethyl cellulose, fabric- softening agents; heavy metal sequestrants such as EDTA; perfumes; and colorants or coloured speckles.
• anti-redeposition agents such as sodium carboxymethylcellulose, straight-chain polyvinyl pyrrolidone and the cellulose ethers such as methyl cellulose and ethyl hydroxyethyl cellulose, fabric- softening agents
• heavy metal sequestrants such as EDTA
• perfumes and colorants or coloured speckles.
• the starting particulate composition may in principle have any bulk density
• the present invention may be especially relevant to tablets of detergent composition made by compacting powders of relatively high bulk density, because of their greater tendency to exhibit disintegration and dispersion problems.
• Such tablets have the advantage that, as compared with a tablet derived from a low bulk density powder, a given dose of composition can be presented as a smaller tablet.
• the starting particulate composition may suitably have a bulk density of at least 400 g/litre, preferably at least 500 g/litre, and possibly at least 600 g/litre.
• a composition which is compacted into a tablet or tablet region may contain particles which have been prepared by spray-drying or granulation and which contain a mixture of ingredients. Such particles may contain organic detergent surfactant and some or all of the water-softening agent (detergency builder) which is also present in a detergent tablet.
• Granular detergent compositions of high bulk density prepared by granulation and densification in a high-speed mixer/granulator, as described and claimed in EP 340013A (Unilever) , EP 352135A (Unilever) , and EP 425277A (Unilever) , or by the continuous granulation/densification processes described and claimed in EP 367339A (Unilever) and EP 390251A (Unilever) , are inherently suitable for use in the present invention.
• the separate particles (i) of the water-insoluble, water- swellable disintegration-promoting material required for this invention, and any optional water-soluble particles to promote disintegration, are preferably mixed with the remainder of the particulate composition prior to compaction.
• a proportion of the further component particles (ii) preferably consist of 25 to 75% by weight of organic surfactant, 25 to 75% be weight of detergency builder, and 0 to 50% by weight of other materials.
• the proportion of other particles with this defined composition is preferably such that these articles comprise from 30 to 99% by weight of the tablet or region thereof .
• Tableting entails compaction of a particulate composition.
• a variety of tableting machinery is known, and can be used. Generally it will function by stamping a quantity of the particulate composition which is confined in a die.
• Tableting may be carried out at ambient temperature or at a temperature above ambient which may allow adequate strength to be achieved with less applied pressure during compaction.
• the particulate composition is preferably supplied to the tableting machinery at an elevated temperature. This will of course supply heat to the tableting machinery, but the machinery may be heated in some other way also.
• any heat is supplied, it is envisaged that this will be supplied conventionally, such as by passing the particulate composition through an oven, rather than by any application of microwave energy.
• the size of a tablet will suitably range from 10 to 160 grams, preferably from 15 to 60 g, depending on the conditions of intended use, and whether it represents a dose for an average load in a fabric washing or dishwashing machine or a fractional part of such a dose.
• the tablets may be of any shape. However, for ease of packaging they are preferably blocks of substantially uniform cross- section, such as cylinders or cuboids.
• the overall density of a tablet for fabric washing preferably lies in a range from 1040 or 1050gm/litre preferably at least HOOgm/litre up to 1400gm/litre. The tablet density may well lie in a range up to no more than 1350 or even 1250gm/litre .
• the overall density of a tablet of some other cleaning composition such as a tablet for machine dishwashing or as a bleaching additive, may range up to 1700gm/litre and will often lie in a range from 1300 to 1550gm/litre .
• a detergent base powder incorporating organic surfactants and detergency builder was made using known granulation technology. It had the following composition, which is shown both as weight percentages of the base powder and as parts by weight.
• zeolite MAP zeolite A24
• zeolite A24 zeolite A24
• Sodium carboxymethyl cellulose is a commonly used water soluble antiredeposition polymer.
• This resulting composition was sieved into various fractions: 355 -lOOO ⁇ m, 500-710 ⁇ m and 1000-1400 ⁇ m.
• Nylin LX-16 is a water-insoluble compacted cellulosic disintegrant obtained commercially from FMC. It was sieved before use into the fractions 500-710 ⁇ m and 1000-1400 ⁇ m. Formulations for making detergent tablets were made by combining 5 parts by weight of a sieved fraction of Nylin LX-16 with 100 parts per weight of a sieved fraction of the detergent composition, as detailed in the following table.
• compositions were compacted with variable force in a laboratory press (Instron 5866) to produce cylindrical tablets with a weight, of approximately 40 grams.
• the applied force F was progressively increased until the tablet breaks, whereupon the force at failure F max in Newtons is recorded.
• the displacement at fracture was measured and the break energy, which is the area under a force-over-displacement graph up to failure, was calculated (Eb in milliJoules) .
• a further measure of the strength of the tablets is their diametrical fracture stress DFS calculated from the equation: where DFS is the diametrical fracture stress in Pascals, P is the applied load in Newtons to cause fracture, D is the tablet diameter in metres and t is the tablet thickness in metres.
• DFS diametrical fracture stress in Pascals
• P the applied load in Newtons to cause fracture
• D the tablet diameter in metres
• t the tablet thickness in metres.
• tablets have a DFS of at least 14kPa, better at least 20 kPa and possibly at least 25kPa.
• the disintegration of the tablets were tested by placing two previously weighed tablets of each type in a washing machine dispenser.
• the dispenser was of a type used in Philips washing machines (AWB 126/127) . Water at 10°C flowing at a rate of 5 litres per minute was passed through the dispenser for a period of one minute, the residue of the tablets remaining in the dispenser were then removed, dried at 100°C for 24 hours to give constant weight and weighed again.
• option D was comparative .
• the mean particle size of its disintegrant was more than 1.4 times the mean particle size of the remainder of the composition.
• Option C was within the invention, but was less preferred because the mean particle size of its disintegrant particles was less than 0.7 times the mean particle size of the remainder of the composition.

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• 2001
  • 2001-11-01 AU AU2002224833A patent/AU2002224833A1/en not_active Abandoned
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