AU2010320062B2

AU2010320062B2 - Method for producing detergent granules

Info

Publication number: AU2010320062B2
Application number: AU2010320062A
Authority: AU
Inventors: Yoshinobu Imaizumi; Takashi Kamei; Kenichiro Kawamoto; Takashi Nakayama; Hiroaki Warita; Masahiro Yamaguchi
Original assignee: Kao Corp
Current assignee: Kao Corp
Priority date: 2009-11-18
Filing date: 2010-11-18
Publication date: 2014-09-18
Anticipated expiration: 2030-11-18
Also published as: WO2011062234A1; JP2011127104A; AU2010320062A1; BR112012011994A2; CN102712885B; CN102712885A

Abstract

Disclosed is a method for producing detergent granules involving a step for dry neutralizing an acid precursor with an alkaline powder material, wherein the particle size distribution is sharp, and it is possible to obtain, with a high yield, detergent granules exhibiting excellent solubility. The method for producing detergent granules exerts the effect of having a sharp particle size distribution, and of being able to obtain, with a high yield, detergent granules exhibiting excellent solubility.

Description

1 DESCRIPTION TITLE OF THE INVENTION: METHOD FOR PRODUCING DETERGENT GRANULES 5 TECHNICAL FIELD [0001] The present invention relates to a method for producing detergent particles using a vessel rotary mixer. 10 BACKGROUND ART [0002] Many detergent compositions containing a non-soap anionic surfactant, such as an alkylbenzenesulfonate, as a main component have been produced. As a method for producing detergent particles, which are one component constituting the detergent compositions as described above, 15 there has been employed a method in which an acid precursor of a non soap anionic surfactant mentioned above is added to be in situ dry neutralized with a water-soluble solid alkali inorganic substance, such as sodium carbonate, instead of directly adding a surfactant (In the present specification, the term "an acid precursor of a non-soap anionic surfactant" 20 may be written as "acid precursor" in some cases.). [0003] For example, a method for producing a detergent composition including the steps of dry-neutralizing components in a high speed mixer and/or granulator at a temperature of 55'C or lower, and thereafter adding a liquid binder thereto to form into particles (Patent Publication 1); a 25 method for producing a detergent composition including the steps of dry- 2 neutralizing components in a high speed mixer and/or granulator at a temperature of 55'C or higher, and thereafter adding a liquid binder thereto to form into particles (Patent Publication 2); and a method for producing a detergent composition including the steps of dry-neutralizing 5 components in a continuous-type high-speed mixer, increasing the bulk density with a moderate-speed mixer, and subsequently cooling and/or drying the product to form into particles (Patent Publication 3) are disclosed. [0004] However, when the detergent particles are produced by utilizing 10 these methods, the particles are likely to be aggregated or formed into coarse particles by adhesive property of a non-soap anionic surfactant produced by the neutralization. In order to suppress the generation of such phenomena, it is necessary to keep its particle shape by operating the agitation mechanism for mixing and the cutting mechanism for 15 disintegration and/or dispersion at high speeds. In this case, the detergent particle having a desired small particle size can be produced by optimizing the agitation and/or cutting conditions. However, it would be difficult to efficiently obtain detergent particles, and the particle size distribution of the resulting particles would become wider. In addition, as to the 20 dissolubility, according to the conventional methods as mentioned above, aggregated particles of the starting raw materials formed, with a non-soap anionic surfactant serving as a binder are present in a relatively large amount. Therefore, it is not easy to improve dissolubility. [0005] As mentioned above, the method according to dry-neutralization is 25 suitable for conveniently producing detergent particles containing an 3 anionic surfactant as a main component; however, the method is basically carried out by forming raw materials into particles with disintegrating aggregates of the raw materials. In the above method, if the anionic surfactant is mixed in a high blending ratio, the aggregation progresses due 5 to its high binding strength, so that it is made difficult to form into particles having smaller particle sizes, which in turn lowers the yield of formed particles. Even if detergent particles having a relative small particle size range are obtained by disintegration, it is somewhat difficult to obtain detergent particles having a sharp particle size distribution and 10 excellent dissolubility in an excellent yield. [0006] On the other hand, Patent Publication 4 describes a method for producing particles including distributing liquid components between a mixer and/or granulator and a fluidized bed granulator, and in Examples, an example of dry-neutralizing an alkylbenzenesulfonic acid with a 15 sodium carbonate or the like in a continuous free-fall mixer (rotary drum with baffles) is disclosed therein. Since this method uses a continuous free-falling mixer, disintegration of aggregates is not carried out, and a shearing force applied to the particles is suppressed; however, the publication does not suggests at all on the kinds of nozzles and a spray 20 liquid droplet diameter upon spraying the alkylbenzenesulfonic acid, so that there yet remain some problems in sharpness of the particle size distribution, yield, and dissolubility. PRIOR ART REFERENCES 25 PATENT PUBLICATIONS H: trintenioven\NRPorb\DCO-IRN\6660 _ I doc-25/08/201j -4 [0007] Patent Publication 1: Japanese Patent Laid-Open No. Hei-3-33199 Patent Publication 2: Japanese Patent Laid-Open No. Hei-4-363398 Patent Publication 3: Japanese Patent Laid-Open No. Hei-3-146599 Patent Publication 4: Japanese Unexamined Patent Publication No. 2007-531803 SUMMARY OF THE INVENTION [00081 Specifically, the present invention relates to a method for producing detergent particles including the step of dry-neutralizing an acid precursor of a non-soap anionic surfactant with an alkaline powder raw material, characterized in that a vessel rotary mixer is used in dry-neutralization, and that the acid precursor is fed with a liquid droplet size in an average particle size of 200 pm or less. [0008a] The present invention relates to a method for producing detergent particles comprising the step of dry-neutralizing an acid precursor of a non-soap anionic surfactant with an alkaline powder raw material having an average particle size of from 5 to 250 pm, characterized in that a vessel rotary mixer, which is a rotary drum mixer or a pan mixer, is used in dry-neutralization, and that the acid precursor is fed at a liquid droplet size in an average particle size of 200 pm or less with a multi-fluid nozzle. [0009] The present invention relates to a method for producing detergent particles including the step of dry-neutralizing an acid precursor with an alkaline powder raw material, whereby the method is capable of obtaining detergent particles having a sharp particle size distribution and excellent dissolubility in an excellent yield. [0010] According to the method of producing detergent particles of the present invention, an effect that detergent particles having a sharp particle size distribution and excellent dissolubility are obtained in an excellent yield is exhibited. MODES FOR CARRYING OUT THE INVENTION 5 [0011] The method for producing detergent particles of the present invention is a method for producing detergent particles including the step of dry-neutralizing an acid precursor of a non-soap anionic surfactant with an alkaline powder raw material, characterized in that a vessel rotary mixer 5 is used in dry-neutralization, and that the acid precursor is fed with a multi-fluid nozzle. [0012] In general, in the formation of particles (granulation) using a vessel rotary mixer, it is possible to homogenously make the powder free flowable, and further a shearing force applied to the powder is suppressed 10 owing to a mixing mechanism involving lifting up of the particles by rotations and sliding and cascading by the deadweight. Therefore, the granulation method using the mixer can be said to be a non-densified granulation method. [0013] In addition, when the granulation is carried out using the above 15 mixer, the granulation does not progress unless liquid components to be supplied have strong adhesive property upon contact with the powder, so that the adhesive property must be exhibited upon the contact with the powder. In general, an acid precursor of a non-soap anionic surfactant exhibits adhesive property upon the contact with an alkaline powder raw 20 material to dry-neutralize. If the acid precursor as described above is supplied to a vessel rotary mixer with a general supplying means, a one fluid nozzle or a pipe, it can be found that the liquid components supplied are less likely to be dispersed homogeneously in the mixer, so that coarse particles are likely to be formed due to large liquid lumps that are locally 25 generated.

6 [0014] In view of the above, when the acid precursor which exhibits adhesive property upon the contact with the powder is supplied to a vessel rotary mixer by spraying the acid precursor with a multi-fluid nozzle such as a two-fluid nozzle, surprisingly, it is found that the powder added to the 5 mixer can be homogeneously formed into particles while suppressing the formation of coarse particles. This is presumably due to the fact that the acid precursor is previously formed into fine liquid droplets with a multi fluid nozzle, so that high dispersibility can be accomplished, and whereby large liquid lumps forming coarse particles are not generated. Therefore, 10 one of the features of the present invention is that the acid precursor which exhibits adhesive property upon the contact with the powder is added to a vessel rotary mixer with a multi-fluid nozzle. [0015] As described above, since a combination of a vessel rotary mixer and a multi-fluid nozzle is intentionally used, an effect which cannot be 15 expected from cases where each of them is used alone that detergent particles having a sharp particle size distribution and excellent dissolubility can be produced in an excellent yield is exhibited. [0016] The mechanisms for obtaining particles having a sharp particle size distribution in an excellent yield are presumably owing to the synergistic 20 effects such that a vessel rotary mixer is used, whereby homogeneous particles with a suppressed shearing force applied to the powder can be obtained, and that fine liquid droplets are formed with a multi-fluid nozzle to allow high dispersibility, so that aggregation caused by adhesive property of a non-soap anionic surfactant formed by dry-neutralization can 25 be suppressed.

7 [0017] Further, the mechanisms for improving dissolubility are presumably owing to the synergistic effects that voids are formed within the particles by a non-densified granulation method with a vessel rotary mixer, and that fine liquid droplets are formed with a multi-fluid nozzle to allow high 5 dispersibility, so that formation of a continuous layer of a surfactant in the particles is suppressed. [0018] An embodiment of dry-neutralization in the method of the present invention is not particularly limited, so long as an embodiment accomplishes dry-neutralization by using a vessel rotary mixer, supplying 10 an acid precursor to an alkaline powder raw material in the mixer by spraying the acid precursor with a multi-fluid nozzle, and further stirring (mixing) the components inside the mixer. An embodiment as one example of the method of the present invention will be explained more specifically hereinbelow. 15 [0019] A. Method for Producing Detergent Particles (1) Acid Precursor of Non-Soap Anionic Surfactant The acid precursor of a non-soap anionic surfactant refers to a precursor of a non-soap anionic surfactant, which has an acidic form and is in a liquid state at an ambient temperature, and is capable of forming a salt 20 by a neutralization reaction. Therefore, the acid precursor is not particularly limited as long as it is a precursor of a known non-soap anionic surfactant having the above-mentioned properties. The acid precursor includes a linear alkylbenzenesulfonic acid (LAS), a olefinsulfonic acid (AOS), an alkylsulfuric acid (AS), an internal 25 olefinsulfonic acid, fatty acid esters of sulfonic acid, an alkyl ether sulfuric 8 acid, a dialkyl sulfosuccinic acid and the like. The acid precursor as mentioned above may be used as a single component or in a combination of two or more components. Among them, the linear alkylbenzenesulfonic acid (LAS) is preferable from the viewpoint of economic advantages, 5 storage stability and foaming property. [0020] Here, as described in Japanese Patent Gazette No. 3313372, an inorganic acid, such as sulfuric acid, may be previously mixed in a given amount to the above-mentioned acid precursor. [0021] The amount of the non-soap anionic surfactant in the resulting 10 detergent particles is preferably from 10 to 45% by weight, and more preferably from 13 to 35% by weight, of the detergent particles, from the viewpoint of detergency and from the viewpoint of particle-forming property. [0022] The temperature of the acid precursor upon supplying is not 15 particularly limited, and the temperature is, for example, preferably from 100 to 80 0 C, and more preferably from 200 to 70'C, from the viewpoint of stability of the acid precursor. [0023] (2) Alkaline Powder Raw Material The alkaline powder raw material includes ones usable as alkalizing 20 agents in ordinary detergent compositions, and exemplified by sodium carbonate, sodium hydrogencarbonate, sodium silicate, potassium carbonate, calcium carbonate, and the like. These may be used alone or as a mixture of two or more kinds. Among the alkaline powder raw materials, a preferred embodiment includes sodium carbonate. 25 [0024] The alkaline powder raw material has an average particle size of 9 preferably from 1 to 500 [tm, more preferably from 3 to 450 tm, even more preferably from 5 to 350 rim, and still even more preferably from 5 to 250 tm, from the viewpoint of formation of particles. [0025] Sodium carbonate can be used in the forms of light soda ash (light 5 ash) and heavy soda ash (dense ash), and it is preferable to use light ash, from the viewpoint of reactivity with an acid precursor. When dense ash is used, it is more preferably to use in a combination with light ash having a particle size of from 1 to 50 [tm, whereby detergent particles having a high bulk density can be produced, while maintaining the reactivity with the 10 acid precursor. [0026] In addition, the alkaline powder raw material is capable of functioning as a detergent builder and an alkalizing agent in a final composition. Therefore, it is preferable that the amount of the alkaline powder raw material is an amount resulting from addition of the alkaline 15 powder raw material for exhibiting the above-mentioned function to an amount necessary for neutralization of the acid precursor (amount equivalent for neutralization). In other words, the amount of the alkaline powder raw material is preferably an amount substantially larger than the amount equivalent for neutralization, and the amount of the alkaline 20 powder raw material is, for example, preferably from 1 to 35 times, more preferably from 2 to 30 times, and even more preferably from 3 to 25 times, the amount equivalent for neutralization. When an inorganic acid is used together with the acid precursor, the amount equivalent for neutralization would result in further addition of an amount necessary for 25 neutralization of the inorganic acid.

10 [0027] In addition, the average particle size of the alkaline powder raw material is not particularly limited. In a case where a surfactant is blended in a high proportion, the alkaline powder raw material may be used after pulverization to a size of from 1 to 50 [tm, from the viewpoint of 5 improvement in yields. Here, the average particle size of the alkaline powder raw material is a value calculated on a volume basis, the value measured, for example, with a laser diffraction particle size analyzer: LA 920 (manufactured by HORIBA, Ltd.). [0028] (3) Vessel Rotary Mixer 10 It is preferable that the vessel rotary mixer is a rotary drum mixer or a pan mixer. The rotary drum mixer is not particularly limited, so long as the treatment is carried out while rotating a cylinder of the rotary drum, and, in addition to a horizontal or slightly slanted rotary drum mixer, a conical rotary drum granulator (mixer), a multi-stage conical rotary drum 15 granulator (mixer) or the like can be also used. These apparatuses can be used in any one of batch process or continuous process. [0029] Here, in a case where a coefficient of friction of the side wall between the detergent particles and an inner wall of the vessel rotary mixer is small so that it is difficult to apply sufficient upward lifting movements 20 to the detergent particles, plural baffles may be provided to the inner wall of the vessel. By providing the baffles, upward lifting movements of the particles are made possible, thereby improving powder miscibility and solid-liquid miscibility. [0030] The operating conditions for the vessel rotary mixer are not 25 particularly limited so long the they are the conditions that the component 11 in the mixer can be stirred. The operating conditions in which a Froude number as defined by the following formula of from 0.005 to 1.0 are preferred, and the operating conditions with a Froude number of 0.01 to 0.6 are more preferred. 5 Froude number: Fr = V2/(R x g) wherein V: peripheral speed [m/s], R: a radius [m] from the center of rotation to the circumference of the rotated object, and g: a gravitational acceleration rate [m/s 2 1. 10 [0031] (4) Other Powder Components To the vessel rotary mixer, a known substance generally usable in the field of detergent compositions may be added together. [0032] The substance includes tripolyphosphates, crystalline or amorphous alkali metal aluminosilicates (zeolite), crystalline silicates, fluorescers, 15 pigments, redeposition preventing agents, such as polycarboxylate polymer and carboxymethyl cellulose sodium, particle-form surfactants, such as fatty acids or salts thereof, linear alkylbenzenesulfonates, and alkyl sulfates, spray-dried powders, silica, diatomaceous earth, calcite, kaolin, bentonite, sodium sulfate, sodium sulfite, and the like. The substance may 20 be optionally used in accordance with its application. In a case where a tripolyphosphate or sodium sulfate is added, the substance may be previously pulverized to have a small average particle size and then added, from the viewpoint of suppressing aggregation of the detergent particles accompanying the neutralization reaction of the acid precursor. The 25 smaller the average particle size of the tripolyphosphate or sodium sulfate, 12 the higher the yield; however, the average particle size is preferably 1 tm or more, from the viewpoint of productivity for industrially obtaining detergent particles having small particle sizes, and the average particle size is preferably 50 tm or less, from the viewpoint of suppressing aggregation 5 of the detergent particles. Here, the average particle size of the tripolyphosphate or sodium sulfate is a value calculated on a volume basis, the value measured, for example, with a laser diffraction particle size analyzer: LA-920 (manufactured by HORIBA, Ltd.). [0033] Among the above-mentioned substances, when an alkali metal 10 aluminosilicate (zeolite) is used, the alkali metal aluminosilicate (zeolite) is contained in an amount of preferably 0.1% by weight or more, more preferably 0.5% by weight or more, and even more preferably 1% by weight or more, of the detergent particles, from the viewpoint of improvement in free flowability, suppression in bleed-out property and 15 caking, and improvement in detergency, and the alkali metal aluminosilicate (zeolite) is contained in an amount of preferably 20% by weight or less, more preferably 15% by weight or less, even more preferably 10% by weight or less, and still even more preferably 5% by weight or less, of the detergent particles, from the viewpoint of rinsability 20 and dissolubility. [0034] The above-mentioned substance may be added together with an alkaline powder raw material before adding an acid precursor, or the substance may be added after adding an acid precursor. In a case where an alkali metal aluminosilicate, silica, diatomaceous earth, or calcite is added, 25 these components are used as a surface-modifying agent to thereby achieve 13 improvement in free flowability and improvement in storage stability, so that it is preferable that the substance is added after adding the acid precursor. [0035] (5) Multi-Fluid Nozzle 5 In the present invention, it is preferable that an acid precursor is supplied with a multi-fluid nozzle. By using the nozzle, fine liquid droplets can be formed to allow dispersibility. The multi-fluid nozzle refers to a nozzle that allows to flow a liquid component and a gas for forming fine droplets, such as the air or nitrogen, in independent pathways, 10 to communicate to a portion in the vicinity of a tip end portion of the nozzle, and mixing and forming fine droplets. As the multi-fluid nozzle, a two-fluid nozzle, a three-fluid nozzle, a four-fluid nozzle, or the like can be used. In addition, a mixing section of the acid precursor and the gas for forming fine droplets may be any one of an internal mixing type where the 15 mixing is carried out within a tip end portion of the nozzle, or an external mixing type where the mixing is carried out in the external of a tip end portion of the nozzle. [0036] The multi-fluid nozzle mentioned above includes internal mixing type two-fluid nozzles manufactured by Spraying Systems Japan K.K., 20 Kyoritsu Gokin Co., Ltd., H. IKEUCHI Co., Ltd., and the like; external mixing type two-fluid nozzles manufactured by Spraying Systems Japan K.K., Kyoritsu Gokin Co., Ltd., Atomax Co., Ltd., and the like; external mixing four-fluid nozzles manufactured by fujisaki electric co., ltd., and the like. 25 [0037] In addition, the liquid droplet size of the liquid droplets of the acid 14 precursor can be adjusted by varying the balance between a flow rate of the acid precursor and a flow rate of a gas for forming fine droplets. In other words, the more increased the flow rate of the gas for forming fine droplets based on a constant flow rate of the acid precursor, the smaller the 5 liquid droplet size. Further, the lower the flow rate of the acid precursor based on a constant flow rate of the gas for forming fine droplets, the smaller the liquid droplet size. [0038] For example, in a case where a two-fluid nozzle is used, for example, it is preferable to feed the acid precursor under the following conditions. 10 The flow rate for gas for forming fine droplets can be easily adjusted by adjusting a gas spraying pressure of forming fine droplets. The gas spraying pressure of forming fine droplets is preferably 0.1 MPa or more, from the viewpoint of liquid dispersibility, and the gas spraying pressure is preferably 1.0 MPa or less, from the viewpoint of loads on the facilities. 15 In addition, the spraying pressure for the acid precursor is not particularly limited, and the spraying pressure is, for example, preferably 1.0 MPa or less, from the viewpoint of loads on the facilities. [0039] As a result of intensive studies on the influences of the differences in liquid droplet sizes on the yield of the detergent particles obtained and 20 the amount of coarse particles, the acid precursor has a liquid droplet size in an average particle size of preferably 200 iim or less, more preferably from 1 to 200 [tm, even more preferably from 3 to 150 tm, and even more preferably from 10 to 58 [tm, from the viewpoint of yield. The smaller the liquid droplet size, the more surely the aggregation during dry 25 neutralization can be suppressed; however, the lowering of the flow rate of 15 the acid precursor leads to an increase in the time period for addition, thereby lowering productivity. Therefore, for example, the rate of addition can be effectively increased while maintaining the formation of fine liquid droplets by using plural multi-fluid nozzles and lowering a flow rate per 5 each nozzle. [0040] On the other hand, by having a rate of addition in a given range, accumulation of unreacted acids on the particle surface is suppressed, so that an excellent yield is obtained by fine dispersion effect with the multi fluid nozzle. Therefore, it is preferable that the acid precursor is added, for 10 example, at a rate of addition [%/min], which is a value calculated by dividing a liquid-powder ratio ((weight of the acid precursor/the weight of the powder supplied ) x 100) [%] by addition time [min], within the range of preferably from 0.1 to 15%/min, and more preferably 0.5 to 10%/min. In a case where the component listed in the above (4) is supplied to a 15 mixer, "weight of the powder supplied" includes the weight of this component. In a case where the above-mentioned inorganic acid is used together, the weight of the acid precursor does not include the weight of the inorganic acid. [0041] Here, the average particle size of the liquid droplet size of the acid 20 precursor is a value calculated on a volume basis, which is a value measured, for example, with a laser diffraction particle size analyzer: Spraytec (manufactured by Malvern Instruments, Ltd.). [0042] (6) Other Liquid Components In the present invention, the detergent particles may be produced by 25 further adding other liquid components. Other liquid components to be 16 added can be properly selected depending upon the components of the detergent particles intended to be obtained, and a desired liquid component can be used. The timing of adding a liquid component is not particularly limited, and for example, a liquid component may be added before or 5 during the course of the step of dry-neutralizing an acid precursor and an alkaline powder raw material, or after the step, and in a case where a surface-modifying agent is added, it is preferably added before adding the surface-modifying agent. [0043] When a liquid component is added after the above-mentioned dry 10 neutralizing step, the liquid component may be added to a vessel rotary mixer used in the dry-neutralization, or the liquid component may be added to a separate mixer/granulator after discharging the detergent particles obtained by the method of the present invention from the vessel rotary mixer. 15 [0044] In addition, the liquid component includes, for example, optional liquid components usable in ordinary detergent compositions, such as nonionic surfactants, water-soluble polymers (polyethylene glycol, sodium polyacrylate, acrylic acid-maleic acid polymers, and the like), fatty acids, and the like. The liquid component may be used as one component alone 20 or in a combination of two or more components. As the liquid component, the component may be added as a liquid, or the component may be added in the form of an aqueous solution or dispersion. The net amount of the liquid component after removing the medium is preferably 15% by weight or less, and more preferably 10% by weight or less, of the final product 25 detergent particles, from the viewpoint of suppression of aggregation of 17 the detergent particles. [0045] The nonionic surfactant usable as the liquid component is not particularly limited, and it is preferable that the nonionic surfactant is, for example, a polyoxyalkylene alkyl ether prepared by adding an alkylene 5 oxide to an alcohol having 10 to 14 carbon atoms in an amount of from 6 to 22 mol, from the viewpoint of detergency. [0046] Methods for adding these liquid components do not resort to the multi-fluid nozzle described in the present invention but the liquid components are sprayable from any nozzles. 10 [0047] B. Detergent Composition and Method for Production Thereof A detergent composition can be produced by further adding desired components to the detergent particles produced as described above. In other words, the detergent composition of the present invention contains the detergent particles obtained by the method of the present invention. 15 [0048] The components to be added include, for example, enzymes, perfumes, bleaching agents, pigments, and the like. The component may be added to a vessel rotary mixer after the dry-neutralization, or the component may be added to a separate mixer used after discharging the detergent particles obtained by the method of the present invention from 20 the vessel rotary mixer. [0049] C. Physical Properties and Evaluations Indexes for the physical properties of the detergent particles and the like obtained according to the present invention include a bulk density, an average particle size, and free-flowability. In addition, an index for 25 productivity includes yield of detergent. The detergent particles have a 18 bulk density of preferably from 400 to 1,000 g/L. The detergent particles have an average particle size of preferably from 200 to 800 [m, more preferably from 200 to 600 [rm, and even more preferably from 260 to 600 urm. The detergent particles have a free-flowability of preferably from 5 4 to 10 seconds, and more preferably from 4 to 7 seconds. As the yield of detergent, the more the yield approximates 100%, the better, and the yield of detergent is, for example, preferably from 80 to 100%, and more preferably from 90 to 100%. [0050] Further, items for evaluating qualities of the detergent particles 10 obtained include sharpness of the particle size distribution and dissolubility. [0051] These physical properties and methods or evaluating qualities are as explained hereinbelow. [0052] < Measurement Methods of Physical Properties > 15 1. Average Particle Size An average particle size is obtained by vibrating particles for 5 minutes using standard sieves of JIS Z 8801 (sieve openings from 2,000 to 45 sm), and calculating a median size from weight percentages according to the sizes of the sieve openings. More 20 specifically, 12-step sieves having sieve openings of 45 [rm, 63 um, 90 urm, 125 um, 180 um, 250 Rm, 355 [rm, 500 um, 710 urm, 1,000 um, 1,400 urm, and 2,000 rn and a receiving tray are used, and the sieves are stacked on the receiving tray in the order beginning from those sieves having smaller sieve openings, and 100 g of particles are added 25 from above the uppermost sieve having a size of 2,000 um, and a lid is 19 placed over the particles, and attached to a rotating and tapping shaker machine (manufactured by HEIKO SEISAKUSHO, tapping: 156 times/min, rolling: 290 times/min). The particles are vibrated for 5 minutes, and thereafter the weights of the particles remaining on each 5 of the sieves and the receiving tray are measured, and weight proportions (%) of the particles on each sieve are calculated. The weight proportions of the particles in the order beginning from the receiving tray to those sieves having smaller sieve openings are cumulated, and a particle size at which a total is 50% is defined as an 10 average particle size. [0053] 2. Bulk Density Bulk density is measured in accordance with a method prescribed in JIS K 3362. Here, in the present invention, the bulk density of the detergent particles is considered to be a bulk density after excluding 15 particles remaining on a sieve having a size of 2,000 ttm. [0054] 3. Free Flowability A flow time is defined as a time period required for flowing 100 mL of powder from a hopper used in a measurement of bulk density as prescribed in JIS K 3362. The free flowability as expressed by the flow 20 time is preferably 10 seconds or less, more preferably 8 seconds or less, and even more preferably 7 seconds or less. Here, in the present invention, the free flowability of the detergent particles is considered to be flowability after excluding particles remaining on a sieve having a size of 2,000 Rm. 25 [0055] 4. Yield of Detergent 20 The yield of the detergent in the present invention is expressed by a proportion of the particles having sizes of 1,410 pim or less in the detergent particles produced. [0056] < Evaluation Methods for Qualities > 5 1. Sharpness of Particle Size Distribution As an index for the particle size distribution, detergent particles having sizes passing though a 1,410 [tm sieve are fitted and the Rosin Rammler number (R-R number) thereof are calculated and used. In the calculation of the Rosin-Rammler number, the following formulas are used. 10 [0057] log (log (100/R (Dp)))= nlog (Dp) + log(P) R (Dp): a cumulative percentage [%] of powder having particle sizes of Dp tm or more; Dp: a particle size [[tm]; n: a Rosin-Rammler number; and 15 P: a particle size distribution coefficient. More specifically, the weights of the particles remaining on each of the sieves and the receiving tray are measured in accordance with a method similar to that of the measurement of the above average particle size to calculate the weight proportions of the particles (cumulative 20 proportion R(Dp) [km]) on each sieve (opening Dp [[tm]). Moreover, a slope n of a least square approximation linear line when plotting log(log(100/R(Dp))) against each of logDp is defined as the Rosin Rammler number. [0058] The larger the Rosin-Rammler number n, the sharper the particle 25 size distribution. n is preferably 1.5 or more, and more preferably 2.0 or 21 more, from the viewpoint of improvement in dissolubility. [0059] 2. Dissolubility As an index for dissolubility in the present invention, a 60-seconds dissolution ratio of the detergent particles explained hereinbelow can be 5 used. The dissolution ratio is preferably 90% or more, and more preferably 95% or more. [0060] The 60-seconds dissolution ratio of the detergent particles is calculated by the method described below. A 1-liter beaker (a cylindrical form having an inner diameter of 10 105 mm and a height of 150 mm, for example, a 1-liter glass beaker manufactured by Iwaki Glass Co., Ltd.) is charged with 1 liter of hard water adjusted to 20'C and having a water hardness corresponding to 71.2 mg.CaCO 3 /L (a molar ratio of Ca/Mg: 7/3). With keeping the water temperature constant at 20*C with a water bath, water is stirred with a 15. stirring bar [length: 35 mm and diameter: 8 mm, for example, Model "TEFLON(registered trademark) SA" (MARUGATA-HOSOGATA), manufactured by ADVANTEC] at a rotational speed (800 r/m), such that a depth of swirling to the water depth is about 1/3. The detergent particles which are accurately sample-reduced and weighed so as to be 1.0000 g 20 0.0010 g are supplied and dispersed in water with stirring, and stirring is continued. After 60 seconds from supplying the particles, a liquid dispersion of the detergent particles in the beaker is filtered with a standard sieve (diameter: 100 mm) having a sieve-opening of 74 tm as defined by JIS Z 8801 of a known weight. Thereafter, water-containing detergent 25 particles remaining on the sieve are collected in an open vessel of a known 22 weight together with the sieve. Incidentally, the operation time from the start of filtration to collection of the sieve is set at 10 sec ± 2 sec. The insoluble remnants of the collected detergent particles are dried for one hour in an electric dryer heated to 105 C. Thereafter, the dried insoluble 5 remnants are cooled by keeping in a desiccator containing a silica gel (25C) for 30 minutes. After cooling the insoluble remnants, a total weight of the dried insoluble remnants of the detergent, the sieve and the collected vessel is measured, and the dissolution ratio (%) of the detergent particles is calculated by the formula (1): 10 [0061] Dissolution Ratio (%) = {1 - (T/S)} x 100 ... (1) wherein S is a weight (g) of the detergent particles supplied; and T is a dry weight (g) of insoluble remnants of the detergent particles remaining on the sieve when an aqueous solution prepared under the above stirring conditions is filtered with the sieve 15 EXAMPLES [0062] The following examples further describe and demonstrate embodiments of the present invention. The examples are given solely for the purposes of illustration and are not to be construed as limitations of the 20 present invention. In the present Examples, the following raw materials were used, unless specified otherwise. - Alkaline Powder Raw Material Light Ash: Average particle size: 100 [tm, manufactured by Central Glass Co., Ltd. 25 Pulverized Light Ash: Average particle size: 8 tm (product 23 obtained by pulverizing the above-mentioned Light Ash) Dense Ash: Average particle size: 300 [m, manufactured by Central Glass Co., Ltd. - Acid Precursor of Non-Soap Anionic Surfactant 5 Linear Alkylbenzenesulfonic Acid (LAS), "NEOPELEX GS," manufactured by Kao Corporation - Other Raw Materials Polyoxyethylene Alkyl Ether (POE). "EMULGEN 121," manufactured by Kao Corporation 10 Zeolite: Average particle size: 3.5 [tm, manufactured by Zeobuilder Pulverized Sodium Sulfate: Product obtained by pulverizing a product having an average particle size of 200 Rm to an average particle size of 10 sm [0063] In the following Examples and the like, as a vessel rotary mixer, a 15 75-L rotary drum mixer (p 40 cm x L 60 cm) having baffles was used. As a multi-fluid nozzle, a two-fluid nozzle manufactured by Atomax Co., Ltd. under the model number of BN90 was used. [0064] Example 1 One-hundred parts by weight of Light Ash (5.7 kg: 22 times the 20 equivalent amount for neutralization) was stirred in the rotary drum mixer (rotational speed: 30 r/m, Froude number: 0.2). After stirring the components for 30 seconds, 28.4 parts by weight of LAS at 60'C was added thereto, in 6.9 minutes with the two-fluid nozzle under the spraying conditions of a rate of addition of 4.1%/min and air spraying pressure for 25 forming fine droplets of 0.3 MPa, and the mixture was stirred for 3 24 minutes after the addition. Thereafter, the stirring was stopped, and 3.9 parts by weight of the zeolite was added thereto, and the mixture was stirred for one minute under the same conditions as above, and the detergent particles obtained were discharged from the mixer. Here, the 5 spray liquid droplet size (average particle size) of the LAS under the spraying conditions was measured. As a result, the average particle size was found to be 35 tm. [0065] Example 2 One-hundred parts by weight of Light Ash (5.5 kg: 18 times the 10 equivalent amount for neutralization) was stirred in the rotary drum mixer (rotational speed: 30 r/m, Froude number: 0.2). After stirring the components for 30 seconds, 35.4 parts by weight of LAS at 60'C was added thereto, in 8.2 minutes with the two-fluid nozzle under the spraying conditions of a rate of addition of 4.3%/min and air spraying pressure for 15 forming fine droplets of 0.3 MPa, and the mixture was stirred for 3 minutes after the addition. Thereafter, the stirring was stopped, and 6.8 parts by weight of the zeolite was added thereto, and the mixture was stirred for one minute under the same conditions as above, and the detergent particles obtained were discharged from the mixer. Here, the 20 spray liquid droplet size (average particle size) of the LAS under the spraying conditions was measured. As a result, the average particle size was found to be 35 rim. [0066] Example 3 One-hundred parts by weight of Light Ash (5.5 kg: 18 times the 25 equivalent amount for neutralization) was stirred in the rotary drum mixer 25 (rotational speed: 30 r/m, Froude number: 0.2). After stirring the components for 30 seconds, 35.4 parts by weight of LAS at 60'C was added thereto, in 4.4 minutes with the two-fluid nozzle under the spraying conditions of a rate of addition of 8.1%/min and air spraying pressure for 5 forming fine droplets of 0.44 MPa, and the mixture was stirred for 3 minutes after the addition. Thereafter, the stirring was stopped, and 4.1 parts by weight of the zeolite was added thereto, and the mixture was stirred for one minute under the same conditions as above, and the detergent particles obtained were discharged from the mixer. Here, the 10 spray liquid droplet size (average particle size) of the LAS under the spraying conditions was measured. As a result, the average particle size was found to be 46 ptm. [0067] Example 4 One-hundred parts by weight of Light Ash (5.5 kg: 18 times the 15 equivalent amount for neutralization) was stirred in the rotary drum mixer (rotational speed: 30 r/m, Froude number: 0.2). After stirring the components for 30 seconds, 35.4 parts by weight of LAS at 60*C was added thereto, in 4.4 minutes with the two-fluid nozzle under the spraying conditions of a rate of addition of 8.1%/min and air spraying pressure for 20 forming fine droplets of 0.17 MPa, and the mixture was stirred for 3 minutes after the addition. Thereafter, the stirring was stopped, and 4.1 parts by weight of the zeolite was added thereto, and the mixture was stirred for one minute under the same conditions as above, and the detergent particles obtained were discharged from the mixer. Here, the 25 spray liquid droplet size (average particle size) of the LAS under the 26 spraying conditions was measured. As a result, the average particle size was found to be 98 tm. [0068] Example 5 One-hundred parts by weight of Light Ash (5.5 kg: 18 times the 5 equivalent amount for neutralization) was stirred in the rotary drum mixer (rotational speed: 30 r/m, Froude number: 0.2). After stirring the components for 30 seconds, 35.4 parts by weight of LAS at 60"C was added thereto, in 4.4 minutes with the two-fluid nozzle under the spraying conditions of a rate of addition of 8.1%/min and air spraying pressure for 10 forming fine droplets of 0.14 MPa, and the mixture was stirred for 3 minutes after the addition. Thereafter, the stirring was stopped, and 4.1 parts by weight of the zeolite was added thereto, and the mixture was stirred for one minute under the same conditions as above, and the detergent particles obtained were discharged from the mixer. Here, the 15 spray liquid droplet size (average particle size) of the LAS under the spraying conditions was measured. As a result, the average particle size was found to be 133 tm. [0069] Example 6 One-hundred parts by weight of Pulverized Light Ash (4.9 kg: 12 20 times the equivalent amount for neutralization) was stirred in the rotary drum mixer (rotational speed: 30 r/m, Froude number: 0.2). After stirring the components for 30 seconds, 54.5 parts by weight of LAS at 60*C was added thereto, in 11.0 minutes with the two-fluid nozzle under the spraying conditions of a rate of addition of 4.9%/min and air spraying 25 pressure for forming fine droplets of 0.3 MPa, and the mixture was stirred 27 for 3 minutes after the addition. Thereafter, the stirring was stopped, and 4.7 parts by weight of the zeolite was added thereto, and the mixture was stirred for one minute under the same conditions as above, and the detergent particles obtained were discharged from the mixer. Here, the 5 spray liquid droplet size (average particle size) of the LAS under the spraying conditions was measured. As a result, the average particle size was found to be 35 rim. [0070] Example 7 One-hundred parts by weight of Pulverized Light Ash and 100 parts 10 by weight of Dense Ash (5.8 kg: 24 times the equivalent amount for neutralization) were stirred in the rotary drum mixer (rotational speed: 30 r/m, Froude number: 0.2). After stirring the components for 30 seconds, 50.3 parts by weight of LAS at 60'C was added thereto, in 6.3 minutes with the two-fluid nozzle under the spraying conditions of a rate of 15 addition of 4.0%/min and air spraying pressure for forming fine droplets of 0.3 MPa, and the mixture was stirred for 3 minutes after the addition. Thereafter, the stirring was stopped, and 5.0 parts by weight of the zeolite was added thereto, and the mixture was stirred for one minute under the same conditions as above, and the detergent particles obtained were 20 discharged from the mixer. Here, the spray liquid droplet size (average particle size) of the LAS under the spraying conditions was measured. As a result, the average particle size was found to be 35 lim. [0071] Example 8 One-hundred parts by weight of Light Ash (2.4 kg: 9 times the 25 equivalent amount for neutralization) and 133 parts by weight of 28 Pulverized Sodium Sulfate were stirred in the rotary drum mixer (rotational speed: 30 r/m, Froude number: 0.2). After stirring the components for 30 seconds, a mixture prepared by previously mixing 46.7 parts by weight of LAS and 4.7 parts by weight of a 98% sulfuric acid and 5 heating to 60'C was added thereto, in 2.8 minutes with the two-fluid nozzle under the spraying conditions of a rate of addition of 7.2%/min and air spraying pressure for forming fine droplets of 0.3 MPa, and the mixture was stirred for 2 minutes after the addition. Thereafter, 10.0 parts by weight of Polyoxyethylene Alkyl Ether was added in 0.5 minutes, and the 10 mixture was stirred for 2 minutes after the addition. Thereafter, 2.3 parts by weight of Sodium Polyacrylate was added in 0.5 minutes, and the mixture was stirred for 2 minutes after the addition. Thereafter, the stirring was stopped, and 6.7 parts by weight of the zeolite was added thereto, and the mixture was stirred for one minute under the same 15 conditions as above, and the detergent particles obtained were discharged from the mixer. Here, the spray liquid droplet size (average particle size) of the LAS under the spraying conditions was measured. As a result, the average particle size was found to be 58 [tm. [0072] Example 9 20 One-hundred parts by weight of Light Ash (1.9 kg: 7 times the equivalent amount for neutralization) and 213 parts by weight of Pulverized Sodium Sulfate were stirred in the rotary drum mixer (rotational speed: 30 r/m, Froude number: 0.2). After stirring the components for 30 seconds, a mixture prepared by previously mixing 65.2 25 parts by weight of LAS and 6.5 parts by weight of a 98% sulfuric acid and 29 heating to 60'C was added thereto, in 2.8 minutes with the two-fluid nozzle under the spraying conditions of a rate of addition of 7.5%/min and air spraying pressure for forming fine droplets of 0.3 MPa, and the mixture was stirred for 2 minutes after the addition. Thereafter, 8.7 parts by weight 5 of Polyoxyethylene Alkyl Ether was added in 0.5 minutes, and the mixture was stirred for 2 minutes after the addition. Thereafter, 2.6 parts by weight of Sodium Polyacrylate was added in 0.5 minutes, and the mixture was stirred for 2 minutes after the addition. Thereafter, the stirring was stopped, and 21.7 parts by weight of the zeolite was added thereto, and the 10 mixture was stirred for one minute under the same conditions as above, and the detergent particles obtained were discharged from the mixer. Here, the spray liquid droplet size (average particle size) of the LAS under the spraying conditions was measured. As a result, the average particle size was found to be 58 rtm. 15 [0073] Comparative Example 1 One-hundred parts by weight of Light Ash (5.5 kg: 18 times the equivalent amount for neutralization) was stirred in the rotary drum mixer (rotational speed: 30 r/m, Froude number: 0.2). After stirring the components for 30 seconds, 35.4 parts by weight of LAS at 60*C was 20 added thereto, in 2.7 minutes with a one-fluid nozzle (manufactured by Spraying System Japan K.K., model number: Unijet 8003) under the spraying conditions of a rate of addition of 13.0%/min, and the mixture was stirred for 3 minutes after the addition. Thereafter, the stirring was stopped, and 6.8 parts by weight of the zeolite was added thereto, and the 25 mixture was stirred for one minute under the same conditions as above, 30 and the detergent particles obtained were discharged from the mixer. Here, the spray liquid droplet size (average particle size) of the LAS under the spraying conditions was measured. As a result, the average particle size was found to be 860 [tm. 5 [0074] Comparative Example 2 One-hundred parts by weight of Light Ash (26.4 kg: 22 times the equivalent amount for neutralization) was stirred in a LUdige mixer FKM 130D (manufactured by Matsubo Co., Ltd.). After stirring for 30 seconds under the conditions of a rotational speed of agitation blade of 130 r/m and 10 a rotational speed of a chopper of 3600 r/m, 28.4 parts by weight of the LAS at 60*C was added in 7.0 minutes with a two-fluid nozzle (manufactured by Spraying System Japan K.K., model number: SU29) under the spraying conditions of a rate of addition of 4.1%/min and air spraying pressure for forming fine droplets of 0.3 MPa, and the mixture 15 was stirred for 3 minutes after the addition. Thereafter, the stirring was stopped, and 6.4 parts by weight of the zeolite was added thereto, and the mixture was stirred for one minute under the same conditions as above, and the detergent particles obtained were discharged from the mixer. Here, the spray liquid droplet size (average particle size) of the LAS under the 20 spraying conditions was measured. As a result, the average particle size was found to be 60 [tm. [0075] Comparative Example 3 One-hundred parts by weight of Light Ash (25.3 kg: 18 times the equivalent amount for neutralization) was stirred in a Ldige mixer FKM 25 130D (manufactured by Matsubo Co., Ltd.). After stirring for 30 seconds 31 under the conditions of a rotational speed of agitation blade of 130 r/m and a rotational speed of a chopper of 3600 r/m, 35.4 parts by weight of the LAS at 60'C was added in 3.4 minutes with a one-fluid nozzle (manufactured by Spraying System Japan K.K., model number: Unijet 5 8010) under the spraying conditions of a rate of addition of 10.5%/min, and the mixture was stirred for 3 minutes after the addition. Thereafter, the stirring was stopped, and 6.8 parts by weight of the zeolite was added thereto, and the mixture was stirred for one minute under the same conditions as above, and the detergent particles obtained were discharged 10 from the mixer. Here, the spray liquid droplet size (average particle size) of the LAS under the spraying conditions was measured. As a result, the average particle size was found to be 510 [tm. [0076] Comparative Example 4 One-hundred parts by weight of Light Ash (4.93 kg) was stirred in 15 the rotary drum mixer (rotational speed: 30 r/m, Froude number: 0.2). After stirring for 10 seconds, 35.2 parts by weight of polyoxyethylene lauryl ether (EMULGEN 106, manufactured by Kao Corporation) at 60*C was added thereto in 9.4 minutes with the two-fluid nozzle under the spraying conditions of a rate of addition of 3.7%/min and air spraying 20 pressure for forming fine droplets of 0.3 MPa, and the mixing was continued for 1 minute after the addition to carry out formation of particles. Thereafter, the stirring was stopped, and 6.8 parts by weight of the zeolite was added thereto, and the mixture was stirred for one minute under the same conditions as above, and the detergent particles obtained were 25 discharged from the mixer.

32 [0077] Comparative Example 5 One-hundred parts by weight of Light Ash (4.93 kg) was stirred in the rotary drum mixer (rotational speed: 30 r/m, Froude number: 0.2). After stirring for 10 seconds, 35.2 parts by weight of polyoxyethylene 5 lauryl ether (EMULGEN 106, manufactured by Kao Corporation) at 60'C was added thereto in 9.4 minutes with the two-fluid nozzle under the spraying conditions of a rate of addition of 3.7%/min and air spraying pressure for forming fine droplets of 0.3 MPa, and the mixing was continued for 1 minute after the addition to carry out formation of particles. 10 Thereafter, the stirring was stopped, and 40.9 parts by weight of the zeolite was added thereto, and the mixture was stirred for one minute under the same conditions as above, and the detergent particles obtained were discharged from the mixer. [0078] Components of the raw materials for the detergent particles, 15 conditions and results of Examples and the like given above are shown in the following tables. [0079] 33 [Table 1] C) 00 CL O X 000 " E C NrD 00 N 00 o i1 CDl 0 00 - W e- CI o to z >) to m 0zcz 0 m z -. 2 6 In 6 o 0 m = -0 z I 0 I,. = x In Q.) r - ,o o o0o = 3 0 0 u 2 gZ 11 0. C/ r N 1 34 [0080] [Table 2] N UN .~- n r CD Lx-~ F) - ~ If ~ c r-1 en 0 N 'n 0_ r_ e ~ \O \ 0q C- 0 00 N 00 t-- 00rq I ~ ~ L encc N N O tf a,\ kc N nC N c 00 en m \ 6c 6- L Ln en (:n N C 00 Ill 6) en \N10 I en 00 Nn \O C ONI men 00 en ml m ~ 6 It~ CON V 00007 0- \O "2 ~ J ~ en Nn ir) en n O7 35 [0081] It could be seen that the detergent particles obtained in Examples 1 to 9 have yields of detergent as high as 80% or more, and the Rosin Rammler number (R-R Number in the table), indexes for the particle size distribution of 1.5 or more, so that the particles having a sharp particle size 5 distribution were obtained in excellent yields. [0082] On the other hand, as to Comparative Example 1, it could be seen that the particles had an yield of detergent as low as 67%, and the Rosin Rammler number of also 1.0, so that the resulting detergent particles had a broadened particle size distribution. As to Comparative Example 2, 10 although the particles are not observed to have a lowered yield, the particles had the Rosin-Rammler of 1.1, so that the resulting detergent particles had a broadened particle size distribution. Here, as to Comparative Example 2, powders stuck to wall sides or agitation shaft in the mixer were observed in large amounts. As to Comparative Example 4, 15 the resulting detergent particles are wet powders, in a state that the measurements of the physical properties were impossible to be taken. As to Comparative Example 5, the amount of zeolite is increased more than that of Comparative Example 4, thereby obtaining detergent particles of which physical properties were measurable; however, the resulting 20 detergent particles had an average particle size of 138 [m. Since Light Ash before the formation of particles had an average particle size of 100 [tm, the formation of particles is hardly progressed, the reasons therefor including weak adhesive property upon the contact with the powder. [0083] As to the dissolubility, from the comparison between Example 2 and 25 Comparative Example 3, Example 2 had a dissolution ratio of 97%, C \NRPorbl\DCC\FMT469394,l1.DOC.2411)/2012 - 36 whereas Comparative Example 3 had a dissolution ratio of 78%, so that Example 2 according to the present invention had an excellent dissolution ratio despite of the large average particle size. [00841 In addition, from the comparison between Examples 3 to 5, those of Example 3 5 in which the liquid droplet size of the acid precursor had an even finer average particle size had more excellent yield of detergent. INDUSTRIAL APPLICABILITY [0085] According to the present invention, detergent particles having a sharp particle 10 size distribution and excellent dissolubility can be produced in excellent yield. The detergent particles can be used as a detergent composition for various applications such as laundry detergents, or as a constituent for the detergent composition. 10086] The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as 15 an acknowledgment or admission or any form of suggestion that that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates. [0087] Throughout this specification and the claims which follow, unless the context 20 requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

Claims

1. A method for producing detergent particles comprising the step of dry-neutralizing an acid precursor of a non-soap anionic surfactant with an alkaline powder raw material having an average particle size of from 5 to 250 rim, characterized in that a vessel rotary mixer, which is a rotary drum mixer or a pan mixer, is used in dry neutralization, and that the acid precursor is fed at a liquid droplet size in an average particle size of 200 pm or less with a multi-fluid nozzle.

2. The method according to claim 1, wherein the alkaline powder raw material is one or more members selected from the group selected from sodium carbonate, sodium hydrogencarbonate, sodium silicate, potassium carbonate and calcium carbonate.

3. The method according to claim 1 or 2, wherein the acid precursor has a liquid droplet in an average particle size of from 3 to 150 gm.

4. The method according to claim 1 or 2, wherein the acid precursor has a liquid droplet in an average particle size of from 10 to 58 gm.

5. The method according to any one of claims I to 4, wherein the acid precursor of a non-soap anionic surfactant is a linear alkylbenzenesulfonic acid.

6. The method according to any one of claims 1 to 5, wherein the amount of the alkaline powder raw material to be added is an amount of 1 to 35 times an amount equivalent for neutralization of the acid precursor of a non-soap anionic surfactant.

7. The method according to any one of claims I to 5, wherein the amount of the alkaline powder raw material to be added is an amount of 2 to 30 times an amount equivalent for neutralization of the acid precursor of a non-soap anionic surfactant.

8. The method according to any one of claims 1 to 5, wherein the amount of the C:\NRPotbDCC\FMT\469394xL DOC-24111/2012 - 38 alkaline powder raw material to be added is an amount of 3 to 25 times an amount equivalent for neutralization of the acid precursor of a non-soap anionic surfactant.

9. The method according to any one of claims 1 to 8, wherein the non-soap anionic 5 surfactant is contained in an amount of from 10 to 45% by weight of the detergent particles obtained.

10. The method according to any one of claims I to 8, wherein the non-soap anionic surfactant is contained in an amount of from 13 to 35% by weight of the detergent 10 particles obtained.

11. The method according to any one of claims 1 to 10, wherein the acid precursor is fed at a temperature of from 100 to 80'C. 15

12. The method according to any one of claims 1 to 11, wherein the detergent particles have a bulk density of from 400 to 1,000 g/L.

13. The method according to any one of claims I to 12, wherein the multi-fluid nozzle is a two-fluid nozzle, and the gas spraying pressure of forming fine droplets is from 20 0.1 to 1.0 MPa.

14. The method according to any one of claims I to 13, wherein the detergent particles obtained have an average particle size of from 200 to 800 pm. 25

15. The method according to any one of claims I to 14, wherein the vessel rotary drum mixer has a Froude number of from 0.005 to 1.0.

16. The method according to any one of claims I to 15, wherein the detergent particles obtained have a free-flowability of from 4 to 10 seconds. 30

17. The method according to any one of claims I to 16, wherein the acid precursor is C:\NRPonbl\DCC\FMT469394X_ .DOC-24/1W2012 - 39 fed at a rate of addition [%/min], which is a value calculated by dividing a liquid powder ratio ((weight of the acid precursor/the weight of the powder supplied) x 100) [%] by addition time [min], within the range of from 0.1 to 15%/min. 5

18. The method according to any one of claims I to 17, wherein an alkali metal aluminosilicate is contained in an amount of from 0.1 to 20% by weight of the detergent particles.

19. The method according to claim 1 substantially as hereinbefore described with 10 reference to any one of the Examples.