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
  • C11D1/00—Detergent compositions based essentially on surface-active compounds; Use of these compounds as a detergent
  • C11D1/02—Anionic compounds
  • C11D1/04—Carboxylic acids or salts thereof
• • 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
  • C11D1/00—Detergent compositions based essentially on surface-active compounds; Use of these compounds as a detergent
  • C11D1/02—Anionic compounds
  • C11D1/12—Sulfonic acids or sulfuric acid esters; Salts thereof
  • C11D1/22—Sulfonic acids or sulfuric acid esters; Salts thereof derived from aromatic compounds
• • 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
  • C11D11/00—Special methods for preparing compositions containing mixtures of detergents
  • C11D11/02—Preparation in the form of powder by spray drying
• • 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
  • C11D17/06—Powder; Flakes; Free-flowing mixtures; Sheets
• • 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
  • C11D3/046—Salts
• • 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
  • C11D3/10—Carbonates ; Bicarbonates
• • 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
  • C11D3/3703—Macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
  • C11D3/3719—Polyamides or polyimides
• • 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
  • 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
  • C11D3/3784—(Co)polymerised monomers containing phosphorus

Definitions

• the present invention relates to the field of detergent powders, especially laundry detergent powders, and their production. More in particular, it relates in a first aspect to a process for the production of a detergent granule comprising at least 40% by weight of an anionic surfactant and suitable for use as a granular detergent composition or a component thereof. In a second aspect the invention relates to a detergent granule comprising at least 40% by weight of an anionic surfactant and which is obtainable by said process. In a third aspect the invention to relates detergent compositions comprising such granules.
• This invention relates to the production of detergent granules comprising a surfactant system that gives effective washing.
• the invention relates to a process to produce such granules by spray-drying an aqueous slurry.
• US2298650 discloses a detergent composition in particulate form made by spray-drying an aqueous solution or suspension comprising sodium sulfate and optionally sodium carbonate, and certain alkylated aromatic hydrocarbon sulfonic acid salts. It is well known to prepare granular detergent products or powders by spray-drying of aqueous slurries.
• Such processes comprise the steps of preparing aqueous slurry comprising from 20 to 60% by weight water, followed by atomising slurry under high pressure to form droplets and then drying these in a counter-current spray-drying tower.
• Typical tower inlet and outlet temperatures are from 250-400°C and 80-120°C, respectively.
• EP-A-1 914 297 discloses a process for the preparation of a spray-dried detergent powder having a bulk density of 426g/l or less, wherein the spray-dried detergent powder comprises an anionic detersive surfactant and from 0% to 10% by weight zeolite builder and from 0% to 10% by weight phosphate builder, and wherein the process comprises the step of:
• EP-A-221 776 describes a process for the production of a porous, zero-phosphate powder suitable for use as a base for a granular detergent composition or a component thereof and capable of absorbing and retaining substantial quantities of liquid or liquefiable detergent components in liquid form, which process comprises the steps of (i) preparing an aqueous slurry comprising sodium carbonate, and optionally also comprising sodium sulphate, (ii) drying the slurry to form a powder, the process being characterised in that the total amount of sodium carbonate and (if present) sodium sulphate is at least 20 percent by weight based on the dried powder, the weight ratio of sodium carbonate to sodium sulphate (when present) in the slurry is at least 0.37:1, and from 0.1 to 60 percent by weight, based on the total amount of sodium carbonate and (if present) sodium sulphate in the dried powder, of a crystal growth modifier which is a polymeric polycarboxylate is incorporated in the slurry not later than the sodium carbon
• the resulting high anionic detergent powders usually have a low bulk density and are difficult to handle and store and have higher packaging costs.
• spray-drying is an energy intensive process and it would be interesting from an environmental point of view to improve the current detergent manufacturing technology in this respect.
• Environmental aspects of detergent manufacturing processes are considered to be important, not only by the manufacturers but also by the consumers who are increasingly interested in the sustainability of our economic activities.
• spray-dried detergent granules having an anionic detergent contents greater than 50 wt% may be prepared from a slurry comprising Na 2 SO 4 and Na 2 CO 3 wherein the molar ratio of Na 2 SO 4 to Na 2 CO 3 is in range of 1 : 0.9 to 1 : 1.3, and whereby the double salt Na 2 SO 4 .Na 2 CO 3 is formed.
• the process according to the invention comprises the steps of (i) neutralising an anionic surfactant precursor with a source of alkali, (ii) adding Na 2 CO 3 and Na 2 SO 4 to form a slurry and (iii) spray-drying the obtained slurry to form a granule, whereby the molar ratio of Na 2 SO 4 to Na 2 CO 3 is in range of 1 : 0.9 to 1 : 1.3, and whereby the double salt Na 2 SO 4 .Na 2 CO 3 is formed and whereby the slurry comprises a polycarboxylate polymer.
• a process for the production of a detergent granule comprising at least 40% by weight of an anionic surfactant and suitable for use as a granular detergent composition or a component thereof, which comprises the steps of (i) neutralising an anionic surfactant precursor with a source of alkali, (ii) adding adding Na 2 SO 4 and Na 2 CO 3 to form a slurry and and (iii) spray-drying the obtained slurry to form a granule, whereby the molar ratio of Na 2 SO 4 to Na 2 CO 3 is in range of 1 : 0.9 to 1 : 1.3, and whereby the double salt Na 2 SO 4 .Na 2 CO 3 is formed and whereby the slurry comprises a polycarboxylate polymer.
• a spray-dried detergent granule comprising greater than 50% by weight of an anionic surfactant and suitable for use as a granular detergent composition or a component thereof, comprising
• a detergent composition comprising the granules according to the present invention.
• the first aspect of the present invention is a process for the production of a detergent granule comprising at least 40% by weight of an anionic surfactant and suitable for use as a granular detergent composition or a component thereof.
• an anionic surfactant precursor is neutralised with a source of alkali to form a surfactant paste.
• the anionic surfactant precursor is an acid precursor of an anionic non-soap surfactant which, when reacted with a source of alkali, will be neutralised to form a salt of the anionic surfactant.
• Anionic surfactant precursors in liquid, pumpable, form are preferred.
• the anionic surfactant precursor is preferably selected from linear alkyl benzene sulphonic acid, fatty acid and mixtures thereof.
• Linear alkyl benzene sulphonic acid is also referred to as LAS acid and HLAS.
• LAS acid yields the corresponding linear alkyl benzene sulphonate (LAS) upon neutralisation.
• the LAS non-soap anionic surfactant has an alkyl chain length of C8-18, more preferably C10-16 and most preferably C12-14.
• Soaps formed by the neutralisation of carboxylic or fatty acids may be used as secondary anionic surfactants in admixture with the non-soap anionic surfactants.
• Preferred carboxylic acids are fatty acids with 12-18 carbon atoms, such as for example fatty acids of coconut oil, palm oil, palm kernel and tallow.
• the fatty acids may be saturated or unsaturated, branched or straight chain. Mixtures of fatty acids may be used.
• Fatty acids may be used at levels of up to 30 wt% based on the anionic surfactant precursor.
• anionic surfactant precursors may be used in a partially preneutralised form without complete loss of the advantageous effects of the invention.
• the surfactant acid is then a mixture of the surfactant acid with neutralised anionic non-soap surfactant.
• the anionic surfactant precursors may be added in admixture with other components.
• Suitable components are neutralised anionic surfactants, for instance the salts of alkyl and/or alkenyl sulphuric acid half-esters (i.e. the sulphation products of primary alcohols) which give alkyl and/or alkenyl sulphates upon neutralisation.
• neutralised anionic surfactants for instance the salts of alkyl and/or alkenyl sulphuric acid half-esters (i.e. the sulphation products of primary alcohols) which give alkyl and/or alkenyl sulphates upon neutralisation.
• non-soap anionic surfactants is primary alcohol sulphate (PAS), especially PAS having a chain length of C10-22, preferably C12-14. Coco PAS is particularly desirable.
• surfactant acids include alpha-olefin sulphonic acids, internal olefin sulphonic acids, fatty acid ester sulphonic acids and primary sulphonic acids. It is also possible to use combinations of surfactant acids as will be apparent to the skilled person.
• nonionic surfactant is typically added to the surfactant acid to reduce viscosity to enable it to be added at a lower temperature.
• Suitable nonionic surfactants that may be used include the primary and secondary alcohol ethoxylates, especially the C8-C20 aliphatic alcohols ethoxylated with an average of from 1 to 50, preferably 1 to 20, moles ethylene oxide per mole of alcohol, and more especially the primary and secondary aliphatic alcohols ethoxylated with an average of from 1 to 10 moles of ethylene oxide per mole of alcohol.
• Non-ethoxylated nonionic surfactants include alkyl-polyglycosides, glycerol monoethers, and polyhydroxyamides (glucamide). As discussed already neutralised anionic surfactant may be mixed with the surfactant acid. This can have the advantage of increasing the throughput of the overall process.
• liquid additives that may be added with the anionic surfactant precursor, or added as separate liquid stream(s), include inorganic acids, such as sulphuric acid, and hydrotropes, such as para toluene sulphonic acid.
• the source of alkali which is reacted with the anionic surfactant precursor can be any suitable source of alkali, in liquid or solid form.
• aqueous alkali metal hydroxide solutions preferably sodium hydroxide solutions, or sodium carbonate.
• Especially preferred are about 50% by weight concentrated aqueous sodium hydroxide solutions.
• the amount of water should be kept to a minimum, because the water will have to be dried off in the subsequent spray-drying step. On the other hand, it should not be so low that the neutralised surfactant paste is too viscous to handle.
• the sodium carbonate may be of any type. Synthetic light soda ash has been found to be especially preferred; natural heavy soda ash is intermediate, while synthetic granular soda ash is the least preferred raw material.
• the surfactant paste is preferably prepared in an agitated mixer provided with an open steam coil to heat the mass to a temperature of about 35-40°C.
• the neutralisation reaction between the anionic surfactant precursor and the source of alkali yields a concentrated surfactant paste, which preferably has a solid content of between 60 to 80% by weight.
• the heat of neutralisation causes the temperature to rise from about 35-40°C to about 75-80°C, where it is maintained. It is beneficial to allow a few minutes additional time to ensure full neutralization.
• sodium sulphate (Na 2 SO 4 ) and sodium carbonate (Na 2 CO 3 ) are added to the surfactant paste to form a slurry.
• the order of addition is not believed to be essential.
• the slurry furthermore comprises a polycarboxylate polymer.
• alkaline silicate and polycarboxylate copolymer may be pumped into the mixer with increased agitation speed improve the fluidity of total mass.
• polyaspartates and polyaspartic acid are advantageously used due to their biodegradability.
• the polymeric polycarboxylates are used in amounts of from 0.1 to 20 wt%, preferably from 0.2 to 5 wt%, most preferably 1 to 5 wt%, based on the total amount of sodium carbonate.
• higher levels of polymer for example, up to 30% by weight based on sodium carbonate, may be present in detergent granules of the invention, or full compositions comprising the detergent granules of the invention, for other reasons, for example, building, structuring or anti-redeposition.
• the polycarboxylate polymer preferably has a molecular weight of at least 1,000, advantageously from 1,000 to 300,000, in particular from 1,000 to 250,000. Polycarboxylates having a molecular weight from 10,000 to 70,000 are especially preferred. All molecular weights quoted herein are those provided by the manufacturers.
• Preferred polycarboxylates are homopolymers and copolymers of acrylic acid or maleic acid. Of special interest are polyacrylates and acrylic acid/maleic acid copolymers. Suitable polymers, which may be used alone or in combination, include the following:
• a second group of polycarboxylate polymers comprises polyaspartic acids and polyaspartates.
• Polyaspartate is a biopolymer synthesised from L-aspartic acid, a natural amino acid. Due in part to the carboxylate groups, polyaspartate has similar properties to polyacrylate.
• One preferred type of polyaspartate is thermal polyaspartate or TPA. This has the benefit of being biodegradable to environmentally benign products, such as carbon dioxide and water, which avoids the need for removal of TPA during sewage treatment, and its disposal to landfill.
• TPA may be made by first heating aspartic acid to temperatures above 180°C to produce polysuccinimide. Then the polysuccinimide is ring opened to form polyaspartate. Because the ring can open in two possible ways, two polymer linkages are observed, an [alpha]-linkage and a [beta]-linkage.
• Mixtures of any two or more polymers, if desired, may be used in the process and detergent granule compositions of the invention.
• the obtained slurry is spray-dried to form a granule, whereby the molar ratio of Na 2 SO 4 to sodium Na 2 CO 3 is in range of 1 : 0.9 to 1 : 1.3, and whereby the double salt Na 2 SO 4 .Na 2 CO 3 is formed. It is believed that the double salt Na 2 SO 4 .Na 2 CO 3 contributes is a favourable manner to the high specific surface area ("SSA") of the granules, which in turn enables them to carry liquid components such as fatty acid/nonionic blends.
• SSA specific surface area
• Typical tower inlet and outlet temperatures of the spray-drying process are from 250-400°C and 80-120°C, respectively.
• a second aspect of the present invention is a spray-dried detergent granule comprising greater than 50% by weight of an anionic surfactant and suitable for use as a granular detergent composition or a component thereof.
• the granules has a relatively high specific surface area which makes them suitable as carrier for absorbing liquid components such as nonionic surfactants or nonionic surfactant/ fatty acid blends.
• the granule according to the invention comprises:
• the detergent granules have an aspect ratio not in excess of two and more preferably are generally spherical in order to reduce segregation from other particles in a formulated powder detergent composition and to enhance the visual appearance of the powder.
• X-ray diffraction is a non destructive analytical method for measuring characteristic diffraction angles and intensities from periodically ordered matter (crystalline material). Intensity and spatial distributions of the scattered X-rays form a specific diffraction pattern, which is the "fingerprint" of the sample and can be used for qualitative and quantitative evaluation, d-value calculation, the determination of crystallite size and defects by the peak shape and polymorphism.
• the detergent composition is a mixture of the detergent composition
• a third aspect of the present invention is a detergent composition, especially a laundry detergent composition, comprising the granules according to the present invention.
• the spray-dried detergent granules of the present invention may be used as such, but they may also be supplemented with other detergent ingredients, components or additives to form a complete detergent composition.
• the detergent granules may be admixed with anything normally used in detergent formulations. They may be dry blended with solid materials and they may advantageously have further liquids added into them, using their spare liquid carrying capacity. It is especially advantageous to add conventional, or even higher than conventional, levels of perfume this way.
• non-soap surfactant for example, cationic, zwitterionic, amphoteric or semipolar surfactants, may also be used with the granules if desired.
• cationic, zwitterionic, amphoteric or semipolar surfactants may also be used with the granules if desired.
• suitable detergent-active compounds are available and are fully described in the literature, for example, in "Surface-Active Agents and Detergents", Volumes I and II, by Schwartz, Perry and Berch.
• Soap may also be present, to provide foam control and additional detergency and builder power.
• the fully formulated composition may comprise up to 8 wt% soap.
• the fully formulated detergent compositions including the detergent granules prepared by the process of the invention may contain conventional amounts of other detergent ingredients, for example, bleaches, enzymes, lather boosters or lather controllers as appropriate, anti-redeposition agents such as cellulosic polymers; anti incrustation agents, perfumes, dyes, shading dyes, fluorescers, sodium silicate; corrosion inhibitors including silicates; inorganic salts such as sodium sulphate, enzymes; coloured speckles; foam controllers; and fabric softening compounds.
• the detergent granule may if desired be mixed with other organic or inorganic builders, typically supplied in the form of granules of either pure builder or mixtures of builder and other ingredients.
• Especially preferred organic builders are acrylic polymers, more especially acrylic/maleic copolymers, suitably used in amounts of from 0.5 to 15 wt%, preferably from 1 to 10wt%. Such polymers may also fulfil the function of the habit modifying polymer.
• the detergent granules of the present invention are hereinafter called a base powder. They may be mixed with another powder obtained from any conventional detergent production process including spray drying or non spray drying processes. As the detergent granules produced by the present invention may be admixed with such other powders, a significant degree of formulation flexibility is obtained and the level of active material in the fully formulated composition may be very high without an unnecessary increase in builder levels.
• the total amount of surfactant present in the fully formulated detergent composition is suitably from to 15 to 70 wt%, although amounts outside this range may be employed as desired.
• the detergent granules may typically form from 30 to 100 wt% of a final fully formulated detergent composition.
• the fully formulated detergent composition incorporating the detergent granules produced by the process of the invention may comprise from 15 to 60 wt%, preferably 20 to 50 wt% of anionic surfactant, this anionic surfactant being derived wholly or in part from the granular product of the spray-drying process.
• the fully formulated detergent composition may comprise from 0 to 35 wt% of nonionic surfactant, and from 0 to 5 wt% of fatty acid soap.
• Fully formulated detergent compositions comprising other ingredients and the detergent granules produced according to the invention preferably have a bulk density of about 350 to 750 g/litre, more preferably at least 450 g/litre.
• Fully formulated detergent compositions may also include other solid ingredients desired for inclusion in the detergent powder, for example, fluorescers; polycarboxylate polymers; antiredeposition agents, for example, sodium carboxymethyl cellulose; or fillers such as sodium sulphate, diatomaceous earth, calcite, kaolin or bentonite.
• fluorescers for example, fluorescers
• polycarboxylate polymers for example, polycarboxylate polymers
• antiredeposition agents for example, sodium carboxymethyl cellulose
• fillers such as sodium sulphate, diatomaceous earth, calcite, kaolin or bentonite.
• solid particulate surfactants for example, alkylbenzene sulphonate and/or alkyl sulphate in powder form, may form part of the solids charge to the mixer to further increase the activity level of surfactant in the granule, however it is preferred to produce all the anionic surfactant by spray-drying.
• the process is generally not sensitive to the type of mixer used, provided intensive mixing is applied. We have found that to obtain the full advantages of the invention the use of a mixer with a chopping action may be advantageous.
• the mixing is carried out in a mixer having and using both a stirring action and a cutting action, most preferably these actions will be separately usable, as described below.
• the cutting action is the preferred chopping action.
• This may be advantageously achieved by the choice of mixer to be a high-speed mixer/granulator having both a stirring action and a cutting action.
• the high-speed mixer/granulator has rotatable stirrer and cutter elements that can be operated independently of one another, and at separately changeable or variable speeds.
• Such a mixer is capable of combining a high-energy stirring input with a cutting action, but can also be used to provide other, gentler stirring regimes with or without the cutter in operation.
• a Lödige mixer is preferred, vertical or horizontal axis cutters are desirable for high anionic loading.
• mixers of the Fukae FS-G type manufactured by Fukae Powtech Co Ltd., Japan are essentially in the form of a bowl-shaped vessel accessible via a top port, provided near its base with a stirrer having a substantially vertical axis, and a cutter positioned on a side wall.
• the stirrer and cutter may be operated independently of one another, and at separately variable speeds.
• the vessel can be cooled.
• Yet another mixer found to be suitable for use in the process of the invention is the Lödige (Trade Mark) FM series batch mixer ex Morton Machine Co. Ltd., Scotland. This differs from the mixers mentioned above in that its stirrer has a horizontal axis.
• Z blade and sigma mixers are suitable mixers having a chopping action.
• BD Bulk Density
• DFR Dynamic Flow Rate
• UCT Unconfined Compression Test
• Powder flow may be quantified by means of the dynamic flow rate (DFR), in ml/s, measured by means of the following procedure.
• DFR dynamic flow rate
• the apparatus used consists of a cylindrical glass tube having an internal diameter of 40 mm and a length of 600 mm. The tube is securely clamped in a position such that its longitudinal axis is vertical. Its lower end is terminated by means of a smooth cone of polyvinyl chloride having an internal angle of 15° and a lower outlet orifice of diameter 22.5 mm.
• a first beam sensor is positioned 150 mm above the outlet, and a second beam sensor is positioned 250 mm above the first sensor.
• the outlet orifice is temporarily closed, for example, by covering with a piece of card, and powder is poured through a funnel into the top of the cylinder until the powder level is about 10 cm higher than the upper sensor; a spacer between the funnel and the tube ensures that filling is uniform.
• the cohesiveness of a powder is classified by the weight (w) as follows:
• An aqueous slurry was prepared in an agitated mixer provided with an open steam coil to heat the mass.
• 2,500 kg of a slurry was prepared involving the following steps.
• a charge made of clean water (523kg) and caustic soda solution (192kg) of 50% purity was dosed to the mixer and heated to a temperature of 40-40°C.
• a pre-weighed quantity (732kg) of commercial grade of sulphonic acid was dosed gradually over a period of 3-4 minutes with continuous agitation to form a neutralized paste. An additional time of 2 minutes was allowed to ensure that the neutralization reaction is complete.
• Preheated alkaline silicate (169kg) and copolymer (114kg) were pumped into the mixer with increased agitation speed so as to improve the fluidity of the total mass. At this stage, it may be preferred to maintain temperature at 75-80°C by use of steam in open coil.
• the steam valve was shut off and sodium sulphate (326kg)/ sodium carbonate (228kg) along with minors (fluorescer 0.91 kg and Sodium Carboxy Methyl Cellulose (SCMC) 16.3kg) were dosed via screw conveyor adjusted to dose over a period of 2-3 minutes and the agitator speed was raised to 70-75rpm.
• the solids were dosed in different sequences to promote formation of crystalline phases after due care was taken to ensure good dispersion/dissolution achieved.
• a final mixing step was allowed for another 2 minutes and then the mixed mass was discharged to the holding tank for subsequent operation in the spray drying tower.
• the above charge sheet was calculated for various formulations and used for making slurries.
• the slurries were transported by a low pressure pump, Reitz mill/magnetic separator and then to the HP pump.
• the slurry was sprayed in a 2.5 diameter spray drier by use of two spraying system nozzles to achieve desired throughput rate of 1100-1200 kg/hr of slurry at pressures of 25 bars.
• the tower was heated by hot air maintained at temperatures of 270-290°C in counter current mode and dried powder was collected at the bottom of tower. Powder moisture content was controlled in the range of 2-3% and minor variations in air inlet temperature were required to maintain steady state conditions.
• Example 1 These base powders of Example 1 were also examined for presence of crystalline phases. Using the D8 Discover ex Bruker-AXS machine, the d-values of the diffraction lines of the samples were obtained and from them the crystalline compounds were identified.

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• 2013
  • 2013-04-09 EP EP13715205.4A patent/EP2841553B1/en active Active
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