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
  • C11D3/02—Inorganic compounds ; Elemental compounds
  • C11D3/04—Water-soluble compounds
  • C11D3/06—Phosphates, including polyphosphates

Definitions

• tablets of a premeasured quantity of material obviates the need for measuring cups used with granules and liquids and eliminates the usual problems of spilling and over or under usage, encountered in employment of granules or liquids.
• tablets because of their size and compactness, are quite useful in dispensing devices 'such as those which can store tablets and inject them into 'a washing machine automatically or which can be placed in public laundries as coin operated machines. Because they are compressed, tablets take up less space than the same'amount of a detergent composition in liquid or granule form.
• the most effective heavy duty synthetic detergent compositions have a strong tendency to stick to the dies which are used to compress the compositions into tablet form. Sticking of the detergent composition to the dies causes breakage of the tablet when the dies are moved apart and when the tablets are ejected.
• Additives which are used in the pharmaceutical tablet making art to prevent ingredients from adhering to the dies are undesirable as additives to the detergent compositions, are difiicult to apply to die surfaces and are not effective in continuous production.
• moderate pressures i.e. in the range of about 150 p.s.i. to about 350 p.'s.i., results in a tablet which is strong and quickly disintegrating if a properly formulated detergent composition is used.
• the use of such moderate pressures overcomes the weakness problems of detergent tablets which are lightly compressed and overcomes the slow disintegration characteristics of the tablets compressed at high pressures.
• the composition should comprise sodium tripolyphosphate and a non-soap, water soluble, organic synthetic detergent in the ratio range of sodium tripolyphosphate to detergent by weight of about 9:1 to about 3:1.
• a greater proportion of sodium tripolyphosphate reduces the detergent efiiciency of the tablet and weakens the tablet since synthetic detergent in an amount corresponding to a 9:1 ratio is the minimum permissible for good detergency and the binding effect it exerts on the sodium tripolyphosphate in the tablet.
• the proportion of synthetic detergent is greater than that corresponding to a 3:1 ratio the resuling tablet disintegrates' too slowly in water. Speed of tablet disintegration increases with increasing amounts of sodium tripolyphosphate.
• the preferred ratio range is 7:1 to 4:1.
• the preferred composition comprises about 40% to about spray dried detergent composition and about 60% to about 20% unhydrated granular sodium tripolyphosphate.
• Not more than about 20% of the granular composition should have a particle size (mean particle diameter) smaller than about .2 mm.
• the average density of the individual particles of the composition should be in the range of about 0.5 to about 1.5, preferably 0.7 to about 1.5.
• the use of a minimum amount of fines and an average particle density in this range is necessary to obtain, upon compression of from about 2.5 to about 1.5 unit volumes of the aforementioned detergent compositions to one unit volume, a detergent tablet having numerous void spaces within the tablet with a total volume in therange of about 40% to about 60% of the tablet volume. This void space should be predominantly interparticulate, i.e. between the particles.
• a network of voids within the tablet permits the water, in which the tablet is placed for use, to enter into the tablet, displace the air in the voids and disintegrate it rapidly.
• the network of voids communicates with the external air.
• a void space of less than about 40% does not provide a network which permits sufficiently rapid disintegration (disintegration in not more than about 3 minutes, preferably not more than about 2 minutes, in an ordinary washing machine containing a load of clothes in water at not less than about F.).
• a void space greater than about 60% pro vides a network which makes the tablet too weak.
• the void space should be predominantly interparticulate in order to provide a network of voids which is sufficiently continuous to provide rapid disintegration according to the above minimum requirement. If the void space is predominantly intraparticulate, i.e. within the particles,
• the particles of detergent to be compressed should not contain more than about 20% fines, i.e. those which are finer than about .2 mm. To avoid breakage and the formation of fines, and to avoid intraparticulate void space, the particles should have an average density in the above mentioned range.
• the composition to be compressed can be a mixture of particles of varying densities if the average density falls within this range. Fine particles are to be avoided because they fill up the interparticulate network of void space within the tablet which is necessary to provide rapid disintegration in the wash water.
• the upper size limit of the particles of detergent composition to be compressed is not particularly critical.
• Granular sodium tripolyphosphate and granular and flake synthetic detergents of the sizes commercially available are useful as are the sizes of the usual spray dried and roll dried compositions comprising these ingredients. Flakes of synthetic detergent as large as A" or more in diameter, for example, can be used.
• the compressive forces being exerted through the dies should be rotated in order to prevent adherence of the tablet ingredients to the dies.
• the compressive forces exerted against both faces of the tablet should be rotated around the axis of compression with respect to the tablet, and preferably with respect to each other. That is, the complementary die sections are preferably rotated in opposite directions around a tablet. However, the dies can be rotated in the same direction, if the tablet remains stationary or the tablet could rotate with the dies at a rate of rotation different from the rate of either of the dies.
• both dies rotate, that the rotation be sufiicient to effect a definite shearing effect between the die surface and the face of the tablet and that there be die rotation during the period of maximum compression. Rotation of the dies during this period prevents adherence of the tablet material to the dies thereby preventing tablet breakage or build up of material which leads to imperfect tablets and eventual clogging of the dies.
• Speed of die rotation is not particularly critical but it is necessary that the dies be rotated through at least about 5 of are (around the axis of compression) preferably at least about to 25, during the period of maximum compression. This much rotation is necessary to effect a shearing force between the die and the tablet face. If the rotation is insufficient to effect a shearing force, particles of detergent composition will adhere to the dies and score the tablet face or break the tablet. Die rotation through an arc greater than about 180 can be used, but is not necessary and would be difficult to effect at high production rates and might tend to cause friction heat which would adversely affect the tablet ingredients, especially those at the surface.
• the tablet After the tablet has been compressed, as'thus far described, it is removed from the die cavity and its surface is moistened with water in an amount of about /z% to about 5% by weight of the tablet.
• the water is applied preferably by a fine spray but other means such as brushing the Water on or subjecting the tablet to steam can be used.
• the water applied to the surface of the tablet hydrates sodium tripolyphosphate on the surface of the tablet and cements tablet ingredients on the surface together to form a strong hard surface on the tablet. This surface makes the tablet non-chalky and more abrasion resistant.
• the strong hard surface is porous and the pores communicate with the network of voids within the tablet thereby permitting rapid entry, into the tablet, of the water in which it is placed for use which, in turn results in rapid disintegration of the tablet.
• the tablet is then dried if necessary to remove any excess Water remaining on the surface of the tablet so that it is dry or at most slightly damp to the touch.
• Much of the water applied to the surface forms a hydrate with sodium tripolyphosphate. Drying can be effected in air or preferably by passing the moistened tablets through an oven on a continuous conveyor.
• Three pronged supports such as those used in the ceramic art are useful to support the tablets during the surface moistening and drying operations.
• the detergent compositions used to make the tablets of this invention should comprise sodium tripolyphosphate and a non-soap, water soluble, organic synthetic detergent in the ratio range of about 9:1 to about 3.0:1, preferably 7:1 to 4:1.
• These detergents may be broadly designated as anionic and nonionic, nonsoap, organic synthetic detergents.
• the cationic nonsoap synthetic detergents are not suitable because of their relative incompatibility with sodium tripolyphosphate.
• the anionic non-soap synthetic detergents may be designated as water soluble salts of organic sulfuric reaction products having in their molecular structure an alkyl or acyl radical of carbon atom content within the range of about 8 to about 18 and a sulfonic acid or a sulfuric acid ester radical.
• anionic detergents are: sodium or potassium alkyl benzene sulfonate in which the alkyl group contains from about 9 to about 15 carbon atoms in either a straight chain or a branched chain which is derived from polymers of propylene; sodium and potassium alkyl glyceryl ether sulfonates, especially those ethers of higher fatty alcohols derived from the reduction of coconut oil; the reaction product of higher fatty acids with sodium or potassium isethionate, where, for example, the fatty acids are derived from coconut oil; sodium or potassium alkyl sulfonates and sulfates, especially those alkyl sulfates derived by the sulfation of coconut 0r tallow fatty alcohols and mixtures of such alkyl sulfates; dialkyl esters of sodium or potassium salts of sulfosuccinic acid, for example, the dihexyl ester; sodium and potassium salts of sulfated or
• Patent 2,486,921 issued to Byerly on November 1, 1949.
• examples of other useful anionic non-soap synthetic detergents are acyl sarcosinates, e.g. sodium N-lauroyl sarcosimate.
• the sodium alkyl benzene sulfonates in which the alkyl group contains about 9 to about 15 carbon atoms are preferred in the practice of this invention.
• Non-ionic non-soap synthetic detergents may be broadly classed as being constituted of a water solubilizing polyoxethylene group in chemical combination with an organic hydrophobic compound such as polyoxypropylene, alkyl phenol, the reaction product of an excess of propylene oxide and ethylene diamine, and aliphatic alcohols.
• the nonionic synthetic detergents have a molecular weight in the range of from about 800 to about 11,000.
• a Well known class of nonionic detergents is made available on the market under the trade name of Pluronic. These compounds are formed by condensing ethylene oxide with a hydrophobic base formed by the condensation of propylene oxide with propylene glycol.
• the molecular weight of the hydrophobic base is of the order of 1500 to 1800.
• the addition of polyoxyethylene radicals to this hydrophobic base increases the water solubility of the entire molecule. Liquid products are obtained up to the point where the polyoxyethylene content is about 50% of the total weight of the condensation product; higher proportions of polyoxyethylene renders the products solid in consistency.
• the molecular Weights of 'Pluronic L61, L64, and F68, for example, are approximately 2000, 3000 and 8000 respectively.
• nonionic synthetic detergents useful in the present invention are: condensation products of to 30 moles of ethylene oxide with one mole of an alkyl phenol containing 6 to 12 carbon atoms, either in a straight or branched chain, in the alkyl group (eg nonyl or octylphenol); condensation products of 10 to 30 moles of ethylene oxide with one mole of an aliphatic straight or branched chain alcohol containing '8 to 18 carbon atoms (e.g.
• the detergent compositions used in this invention should comprise at least 55% of the mixture of sodium tripolyphosphate and non-soap synthetic detergent in the ratios mentioned above.
• Any of the other auxiliary materials generally employed with synthetic detergent compositions can also be included.
• These auxiliary materials can be inorganic or organic in character and can be mixed with the non-soap synthetic detergent and sodium tripolyphosphate in any suitable manner. Examples of such conventional inorganic auxiliary materials are alkali metal silicates, carbonates, sulfates and phosphates (e.g. metaphosphate, pyrophosphate and orthophosphate).
• organic auxiliary materials are carboxy'methyl cellulose, suds builders (e.g. coconut fatty acid mono and di-ethanolamides and lauryl dimethyl amine oxide), N- chloro bleaches, tarnish inhibitors, fluorescent brightening agents, bacteriostatic agents, perfumes, coloring matter, suds depressors and the like.
• the granular detergent composition to be compressed preferably contains from about to about 4 /2% moisture (by weight of the total amount of granules) which acts as a binder for the tablet ingredients, i.e. moisture assists the non-soap synthetic detergent in causing the compressed particles to stick together.
• the moisture content of the composition to be compressed can be adjusted by using ingredients which already contain moisture (e.g. spray dried granules) or if the ingredients are too dry, moisture can be added. But overall its should be less than about 4 /2 A greater amount of moisture results in an undue reduction in the amount of void space when moderate compression pressures are used.
• Moisture can be uniformly added to the granular detergent composition, if necessary, by spraying water onto the granules in a rotary drum or a moving belt for example.
• the preferred moisture content is 1% to 3%.
• liquid non ionic auxiliary binding agent from 0% to about 3% can be used, and when it is used, amounts from to 1 /z% based on the weight of the granules are preferred.
• the liquid Pluronics are preferred as the auxiliary non ionic binding agent.
• the uniform addition of moisture and/or liquid nonionic detergent to the granules to be compressed is intended to include those situations where the moisture and/or nonionic detergent is uniformly added to a portion of the granular material to be compressed which portion is then uniformly mixed with the remainder of the material to be compressed which can be dry and can contain no nonionic detergent.
• the portion containing the moisture or nonionic detergent is preferably .at least 40% of the total amount of granules.
• the liquid non-ionic synthetic detergent can be added to the granules by spraying it on the granules or a portion of the granules.
• the nonionic detergent can be sprayed on the granules in a rotary drum or a moving belt for example.
• the nonionic detergent being sprayed on can be diluted with water if desired.
• the granular detergent composition to be compressed in accordance with the process of this invention can comprise a uniform mechanical mixture of the individual components, a homogeneous mixture such as that obtained by spray drying or roll drying an aqueous slurry of the ingredients, or a mechanical mixture of the ingredients a portion of which constitutes spray dried granules.
• the preferred composition to'be compressed in accordance with this invention comprises about 60% to about 20% unhydrated granular sodium tripolyphosphate and about 40% to about 80% spray dried granules.
• the spray dried granules contain part of the sodium tripolyphosphate in the tablet formulation, all of the non-soap synthetic detergent and any of the minor in- "gredients, such as sodium sulfate, moisture, non-ionic binder, brightening agents or anti-redeposition agents, which are included.
• Spray-dried granules in the above range are preferred because the process of spray drying is a convenient way to ensure that the minor components,
• Unhydrated granular tripolyphosphate in the above range is preferred because it reduces the quantity of product to be spray dried, and more important, it permits the formation of a stronger porous surface on the tablet than is obtainable using 100% spray-dried granules. Since the process of spray drying hydrates much of the sodium tripolyphosphate in the composition being dried, tablet surface hardening by the application of water to compressed spray dried granules is effected mainly through the cementing together of the tablet ingredients and only partially through further hydration of sodium tripolyphosphate.
• the tablet forming apparatus used to perform the process of this invention can be any device which provides a cavity for holding the granular composition to be compressed, opposing dies, both ofwhich can be rotated with respect to the tablet faces, and a means for compression of the granular composition by exerting pressure on at least one of the dies. Tablet making machines known in the art can be adapted to these requirements.
• the tablet making apparatus described in copending application of Robert V. Burt, Serial No. 2,088, filed concurrently herewith now U.S. Patent 3,014,240, is used in the practice of this invention.
• the tablets of this invention will be round of nearly so in at least one dimension.
• Example I A spray-dried granular detergent composition having the following composition was formed:
• the spray dried composition had a density of 0.5. 0.92% (by weight of the spray dried granular composition) of Pluronic L64 was sprayed uniformly on the granules in a rotary dl'lllll. This nonionic detergent sprayon was used to act as a binding agent during tablet compression. The granules were then subjected to an air lift, a gravity separator and a screen whereby the moisture content was reduced to 3% and particles larger in size than 1.4 mm. and most of the particles smaller in size than .2 mm. (mean diameter) were removed. The resulting spray dried composition contained 18% particles having a size smaller than .2 mm.
• the tablet was then placed on a three pronged support and passed through a chamber where the entire surface of the tablet was subjected to a fine spray of water. During this treatment 2 /2% water (by weight of the tablet) was added to the tablet surface. The tablet was then placed in a drying oven at 250 F. for 1.5 minutes. Sodium tripolyphosphate on the surface of the tablet hydrated and detergent ingredients on the surface of the tablet cemented together forming a non-chalky, abrasion resistant, porous surface on the tablet. When the tablet was removed from the oven it was only slightly damp to the touch and was ready for packaging. It weighed two ounces and had a total moisture content of 3.3%. It had a network of voids amounting to 45% of the volume of the tablet. This network was predominantly interparticulate.
• the finished tablets were economically, conveniently and successfully handled and packaged with the aid of high speed machinery.
• the finished tablets when placed in an ordinary washing machine containing a load of soiled clothing in water at F., disintegrated in 80 seconds.
• the detergency effectiveness of the tablet was excellent.
• condensation product of lauryl alcohol and 15 moles of ethylene oxide or the condensation product of 15 moles of ethylene oxide and nonyl phenol can be substituted in equivalent amounts for the Pluronic L64 sprayed on the spray-dried granules in Example I with substantially equal results.
• Compression pressures of 250 p.s.i. and 300 p.s.i. can be used in the process described in Example I with substantially equal results except that the volume of the tablet will be slightly reduced and the time of tablet disintegration will be slightly greater (about 2 and 2 minutes respectively under the above conditions).
• the tablets made in accordance with Example I were made of a low sudsing detergent composition particularly useful in a tumbler-type washing machine where a large amount of foam is not desirable.
• a tablet can be made from a higher sudsing detergent composition by substituting, for the spray dried granular detergent composition used in Example I, a spray dried detergent composition having the following composition.
• the average particle density of the mixture was 1.3.
• the tablet weighed 2 ounces and had a total moisture content of 3%. It had a network of'voids amounting to 45% of the volume of the tablet. This network was predominantly interparticulate.
• the tablet was strong and showed no signs of breakage when subjected'to the stresses and handling typical of packaging and transporting operations.
• the tablet When the tablet was placed in an ordinary washing machine con taining a load of soiled clothing in water at 130 B, it disintegrated in 90 seconds.
• the detergency effectiveness of the tablet was excellent.
• a process for making a detergent tablet the steps of (1) forming a particulate mixture comprising sodium tripolyphosphate and a water soluble, non-soap organic synthetic detergent, selected from the group consisting of anionic and non-ionic detergents in which the weight ratio of sodium tripolyphosphate to said detergent is in the range of about 9:1 to about 3: 1, in which the average density of the particles is in the range of about 0.5 to about 1.5 and in which no more than about 20% of the particles are smaller than about 0.2 mm., (2) pressing from about 2.5 to about 1.5 unit volumes of said mixture into a tablet of one unit volume using a compression pressure in the range of about 150 p.s.i. to about 350 p.s.i.
• the said particulate mixture comprises about 20% to about 60% unhydrated granular sodium tripolyphosphate and about 80% to about 40% of a mixture of sodium tripolyphosphate and the said non-soap synthetic detergent in form of spraydried granules, the weight ratio of sodium tripolyphospate to said non-soap synthetic detergent in the total particulate mixture ranging from 7:1 to 4: 1, the compressive forces are rotated around the axis of compression through an arc of at least about 5 but not more than about 180,
• step (3) is dried.
• a process for making a detergent tablet the steps of (1) forming a particulate mixture comprising sodium tripolyphosphate and a normally solid, water soluble, non-soap, organic synthetic detergent, selected from the group consisting of anionic and non-ionic detergents, in which the weight ratio of sodium tripolyphosphate to said detergent is in the range of about 9:1 to about 3.011, in which the density of particles is in the range of about 10 0.5 to about 1.5, in which no more than about 20% of the particles are smaller than about 0.2 mm., and in which at least a portion of the particles have a coating of a liquid nonionic synthetic detergent in an amount equal to about.
• said liquid nonionic detergent being constituted of a water solubilizing polyoxyethylene group in chemical combination with an organic hydrophobic compound, the mixture containing from about to about i /2% moisture, (2) pressing from about 2.5 to about 1.5 unit volumes of said mixture into a tablet of one unit volume using a compression pressure in the range of about 150 p.s.i. to about 350 p.s.i.
• the said particulate mixture comprises about 20% to about 60% unhydrated granular sodium tripolyphosphate and about to about 40% of a mixture of sodium tripolyphosphate and the said non-soap synthetic detergent in the form of spray-dried granules, the weight ratio of sodium tripolyphosphate to said non-soap synthetic detergent in the total particulate mixture ranging from 7:1 to 4:1, the compressive forces are rotated around the axis of compression through an arc of at least about 5, but not more than about 180, and the tablet treated in step (3) is dried.
• the said synthetic detergent is an alkyl benzene sulfonate, the alkyl radicals containing about 9 to about 15 carbon atoms, and the said liquid nonionic detergent is the condensation product of ethylene oxide and the reaction product of propylene oxide and propylene glycol wherein the polyoxyethylene content is up to about 50% of the total weight of the condensation product.
• a process for making a detergent tablet the steps of (1) forming a particulate mixture comprising sodium tripolyphosphate and a water-soluble, non-soap, organic synthetic detergent selected from the group consisting of anionic and non-ionic detergents, in which the weight ratio of sodium tripolyphosphate to said detergent is in the range of about 9:1 to about 3:1, in which the average density of the particles is in the range of about 0.5 to about 1.5 and in which no more than about 20% of the particles are smaller than about 0.2 mm., (2) pressing from about 2.5 to about 1.5 unit volumes of said mixture into a tablet of one unit volume using a compression pressure in the range of about p.s.i. to about 350 p.s.i.
• a round heavy-duty laundry detergent tablet consisting essentially of a compressed water-soluble particulate mixture consisting essentially of about 20% to about 60% granular sodium tripolyphosphate, prior to compression all of which was unhydrated, and about 80% to about 40% of a mixture, in the form of spraydried granules, of sodium tripolyphosphate and a normally solid water-soluble non-soap organic synthetic detergent selected from the group consisting of anionic and nonionic detergents, the weight ratio of sodium tripolyphosphate to said non-soap synthetic detergent in the total particulate mixture ranging from about 9:1 to about 321, said tablet having a network of void space, which is predominantly interparticulate, in the range of about 40% to about 60% of the tablet volume, said tablet having a strong, hard, non-chalky porous surface of hydrated sodium tripolyphosphate and cemented tablet ingredients, the pores in said surface communicating with said network, said particulate mixture having been compressed at a pressure in the range of about 150 p.s.i
• the detergent tablet of claim 8 wherein the said detergent is an alkyl benzene sulfonate in which the alkyl radical contains about 9 to about 15 carbon atoms.

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• Chemical & Material Sciences (AREA)
• Inorganic Chemistry (AREA)
• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Wood Science & Technology (AREA)
• Organic Chemistry (AREA)
• Detergent Compositions (AREA)

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Cited By (47)

Citations (4)

• 0
  • NL NL259594D patent/NL259594A/xx unknown
  • BE BE632373D patent/BE632373A/xx unknown
• 1959
  • 1959-12-31 US US863173A patent/US3081267A/en not_active Expired - Lifetime
• 1960
  • 1960-12-29 GB GB44667/60A patent/GB957868A/en not_active Expired

Patent Citations (4)

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