DESCRIPTION

PROCESS FOR WASHING AND POWDER DETERGENT COMPOSITION

FIELD OF THE INVENTION

The present invention relates to a process for washing and a powder detergent composition. More specifically, the present invention relates to a process for washing and a powder detergent composition, having excellent redeposition preventing property against soil particles while improving load of labor during hand-washing.

BACKGROUND OF THE INVENTION

In general, a powdery laundry detergent contains a surfactant, a builder for capturing a water-hardness component, a pH buffer, other aids (a detergent enzyme, a fluorescent brightener, a bleaching system and the like), and the like, and regarding those detergent base materials, various improvements have been tried from old times, from the viewpoint of higher performance, improvement of environmental aptitude, lowering of costs, improvement in aptitude in formation of preparations, and the like. In addition, regarding their preparation processes, improvements have repeatedly made, from the viewpoint of conservation of energy, lowering of costs, stability and improvement in quality, and the like. As described above, at present, high-performance powdery laundry detergents have been efficiently supplied by mass-production.

On the other hand, the methods of use for a general user (consumer) of a laundry detergent roughly include hand-washing and washing machine-washing.

While hand-washing enables flexible washing conditions depending upon the washing situations such as the extent of removal of dirt stains and the kinds of items to be washed, physical and mental fatigue are involved in an individual who hand-washes, as compared to washing machine-washing. Especially, in "rub-washing" wherein the items to be washed are rubbed against each other, mechanical forces can be directly applied to sites to be washed, thus being one of the most natural processes for hand-washing. However, a long-period of continuous and repeated work would be burdensome to an individual who handwashes. In addition, since the surface of the items to be washed, such as clothes, is not smooth microscopically, friction is generated when these clothes are actually rubbed together. This friction is felt by the individual who washes as unpleasant factors, such as "rough texture" and "squeakiness," and increases the burden applied physically to the individual from the viewpoint of exhaustion of physical strength by the rub-washing movement. In addition, the local frictions generated during rub-washing cause scratches or cuts on the hands of the individual, which in turn appear as wear on fibers, a so-called "cloth-damage" to the items to be washed. The damage on fibers not only shorten the duration period of clothes but also serve as an accelerating factor with respect to adhesion of dirt stains, thereby further increasing the physical burden required for washing.

On the other hand, as a grapple for providing direct improvement in laundry washing by a general user, while eliminating technological improvements and the like for solving the technological improvement in preparation process and technological development relating to the preparation form, the disadvantage in distribution stage such as storage stability,

conventionally, technological developments have been made by remarking mainly on the aspect of "how to remove dirt stains from an item to be washed and prevent new dirt stains from being adhered," such as improvement of detergency of a detergent, prevention of the redeposition on the washed laundry such as clothes, or prevention of migration of dyes from a pigment detached from other washed laundry, or the aspect of "how to finish the washed laundry," such as imparting a softening property to the washed laundry, or preventing wrinkles of the clothes from being generated (see, for instance, JP-A-Hei 5- 508889, JP-A-Hei 1-98697, JP-A-Hei 7-216389 and JP-A-Hei 6-179893). Taking into consideration the unpleasant factors and physical burden generated during the hand-washing as mentioned above, i.e. "mental and physical burden for an individual who washes," the technological developments focusing on the improvements thereon to reduce the burdens have not been so far made.

JP-A-Hei 6-179893 discloses a technique of preventing color migration using an acrylamide alkylene sulfonic acid-based polymer. However, this technique also does not grapple with improvement in the mental and physical burdens mentioned above for an individual who hand-washes, and is not intended at all to give clothes smoothness upon washing to reduce frictions, and to give smooth feel to clothes in a washing liquid, thereby making hand-washing pleasant experience. Moreover, its redeposition preventing property against soil stains has not been satisfactory.

SUMMARY OF THE INVENTION

The present invention relates to: [1] a process for washing an item to be washed in a washtub containing an

anionic surfactant, a builder for capturing a water-hardness component, an alkaline substance and a sulfonic acid-based polymer, wherein the sulfonic acid- based polymer contains a monomer unit represented by the following formula

(I):

-CH ₂ -CR ¹ -

I ( I ) X - SO ₃ A

wherein A is a hydrogen atom or an alkali metal atom; R ¹ is a hydrogen atom or a methyl group; and X is any one of groups represented by the following formula (II) to (IV):

— Ph — ( II )

wherein Ph is a phenylene group;

- C -O - ( CH ₂ ^ - (HI) O wherein m is a number of from 1 to 6;

C N R / _π/ s

O wherein R ² is a linear or branched alkylene group having 2 to 8 carbon atoms, in a ratio of from 50 to 100% by mol of the entire constituting monomers, and has a weight-average molecular weight of from 1,000,000 to 30,000,000, the process including the steps of contacting an item to be washed with an anionic surfactant, an entire part or a part of which is dissolved in the washtub, and thereafter contacting further with the sulfonic acid-based polymer; [2] a powder detergent composition obtainable by mixing base detergent

particles containing an anionic surfactant, and separately prepared particles therefrom containing 70% by weight or more of a sulfonic acid-based polymer containing a monomer unit represented by the formula (I) as defined in the above [1] in a ratio of from 50 to 100% by mol of the entire constituting monomers, the sulfonic acid-based polymer having a weight-average molecular weight of from

1,000,000 to 30,000,000; and

[3] a detergenjt additive containing 70% by weight or more of a sulfonic acid- based polymer containing a monomer unit represented by the formula (I) as defined in the above [1] in a ratio of from 50 to 100% by mol of the entire constituting monomers, and having a weight-average molecular weight of from 1,000,000 to 30,000,000, wherein the detergent additive has an average particle size of from 50 to 500 μm, a content of particles having sizes of 63 μm sieve opening-pass of 20% by weight or less, and a content of particles having sizes of 1400 μm sieve opening-on of 10% by weight or less.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a graph showing particle size distribution of the particles A obtained in Preparation Example of Sulfonic Acid-Based Polymer Having Different Particle Sizes; Figure 2 is a graph showing particle size distribution of the particles B obtained in Preparation Example of Sulfonic Acid-Based Polymer Having Different Particle Sizes;

Figure 3 is a graph showing particle size distribution of the particles C obtained in Preparation Example of Sulfonic Acid-Based Polymer Having Different Particle Sizes;

Figure 4 is a graph showing particle size distribution of the particles D obtained in Preparation Example of Sulfonic Acid-Based Polymer Having Different Particle Sizes;

Figure 5 is a graph showing particle size distribution of the particles E obtained in Preparation Example of Sulfonic Acid-Based Polymer Having

Different Particle Sizes; and

Figure 6 is, a graph showing particle size distribution of the particles F obtained in Preparation Example of Sulfonic Acid-Based Polymer Haying Different Particle Sizes.

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a process for washing and a powder detergent composition suitable for the process, which are capable of improving unpleasant factors and physical burdens generated upon hand-washing, i.e. "mental and physical burdens for an individual who hand-washes," and having excellent redeposition preventing property against soil particles.

In view of the above-mentioned disadvantages, the present inventors have found that the use of a specified sulfonic acid-based polymer gives appropriate smoothness to clothes upon rub-washing with hands, thereby bringing about an effect of reducing labor loads or the like, and that the redeposition preventing property against soil particles can be dramatically improved by an action of the sulfonic acid-based polymer with other detergent components in a specified order. Based on these findings, the present invention has been accomplished thereby. According to the process for washing of the present invention,

smoothness between the laundry clothes during hand-washing is improved, so that labor load of the individual who hand-washes can be reduced, and at the same time redeposition preventing property against the soil particles can be improved,. Also, by using the powder detergent composition of the present invention, an effect that the individual who hand-washes can evidently enjoy the above-mentioned improvement.

These and,other advantages of the present invention will be apparent from the following description.

A feature of the process for washing of the present invention resides in that the process includes the step of, prior to dissolving a sulfonic acid-based polymer, dissolving in a washing water an entire part or a part of a base detergent component containing an anionic surfactant, a builder for capturing a water- hardness component, and an alkaline substance.

As the process for washing as described above, a process including the step of introducing the detergent components individually into the washing water, while keeping their order may be employed. More specific examples of the process as described above include, for example, a process including the steps of previously preparing an aqueous solution each containing a desired amount of an anionic surfactant or a desired amount of a sulfonic acid-based polymer, and introducing each aqueous solution into a washing water; a process including the steps of directly introducing base detergent particles in the form of solid or particles into a washing water to partly or entire dissolve, and thereafter introducing a sulfonic acid-based polymer in the form of solid or particles thereinto; and the like. In addition, in the case where, for example, base detergent particles in the

form of particles and the sulfonic acid-based polymer in the form of particles are mixed in a batch system, the process for washing includes a process including the step of carrying out the dissolution of the polymer particles more slowly or gradually, than the dissolution of the detergent particles. In other words, the process for washing of the present invention is not limited to a process in which an anionic surfactant in the detergent component and a sulfonic acid-based polymer are simply individually and stepwise introduced into the washing water, and the process may include a process in which the dissolution progress of an anionic surfactant is more rapid than the dissolution progress of the sulfonic acid-based polymer due to the difference in the dissolution speed of the solid or particles making up the anionic surfactant or the sulfonic acid-based polymer, respectively, even if the anionic surfactant and the sulfonic acid-based polymer are added at one time into the washing water. If the dissolution conditions as described above can be realized, the effects of the present invention can be obtained, even when the dissolution in water is started at the same time and progressed in a strict sense.

According to the process for washing of the present invention, smoothness between the laundry clothes during hand-washing is improved, so that labor load of the hand-washing individual can be reduced, and at the same time redeposition preventing property against the soil particles can be improved.

Although not wanting to limit the present invention by theory, it is considered that these effects in the process for washing of the present invention are based on the reduction or loss of affinity of the sulfonic acid-based polymer itself with the soil particles by some sort of interactions existing between the sulfonic acid-based polymer in the present invention and the detergent

components such as an anionic surfactant, thereby improving the dispersibility of the soil particles. Originally, items to be washed, soil particles and the order of addition of each component of the detergent are not considered to define the stable state of the composite system constructed thereby. In other words, although it is not considered that the redeposition preventing property of the soil particles is affected or changed by the order of the action of each of the detergent base materials, if, it is understood that the time period relating to steady state of the detergent base materials, fibers of the items to be washed and adsorption and desorption of soil particles is beyond the range of the time period required for a general wash, the effects that the improvement in the redeposition preventing property against soil particles are brought about by the action order of the detergent base materials can be explained thereby. Specifically, a difference in timing for carrying out the substantial action by each component is considered, contrary to the expectation, to lead to cause significant influence to the deterging results.

< Sulfonic Acid-Based Polymer >

The sulfonic acid-based polymer used in the present invention is a sulfonic acid-based polymer containing a monomer unit represented by the following formula (I):

-CH ₂ -CR ¹ —

I C D

X - SO ₃ A

wherein A is a hydrogen atom or an alkali metal atom; R ¹ is a hydrogen atom or a methyl group; and X is any one of groups represented by the following formula

(II) to (IV):

— Ph - ( II )

wherein Ph is a phenylene group;

— G -O- (CH ₂ ) _ffl — (JII.) O wherein m is a number of from 1 to 6;

— C- N - R ² - , v

Ii H ^uv '

O wherein R ² is a linear or branched alkylene group having 2 to 8 carbon atoms, in a ratio of from 50 to 100% by mol of the entire constituting monomers, and having a weight-average molecular weight of from 1,000,000 to 30,000,000. The ratio of the constituting monomer units in the polymer is 50% by mol or more, from the viewpoint of dispersibility of the soil particles, and the ratio is preferably 70% by mol or more, more preferably 80% by mol or more, even more preferably 85% by mol or more, and even more preferably 90% by mol or more, from the viewpoint of more excellent dispersibility of soil particles. In addition, those containing substantially no other constituting monomers are also preferable as the sulfonic acid-based polymer used in the present invention.

A in the formula (I) is a hydrogen atom or an alkali metal atom; and R ¹ is a hydrogen atom or a methyl group, and preferably R ¹ is a hydrogen atom. In addition, X in the formula (I) is preferably a group that does not lose high polymerizability of the monomer units represented by the above-mentioned formula (I), such as a phenylene group, an ester alkylene group, an amide alkylene group, and X in the formula (I) is more preferably a group represented

by any one of the formulas (II) to (IV):

— Ph — ( II )

wherein Ph is a phenylene group; and

— G - O - ( CH ₂ ) _m — (III) O wherein m is a number of from 1 to 6;

C N R / _R/γ

O wherein R ² is a linear or branched alkylene group having 2 to 8 carbon atoms.

In the monomer units represented by the formula (I) that constitute the sulfonic acid-based polymer, X in the formula (I) is a group represented by the above formulas (II) to (IV), or a mixture of these groups.

When X is a group represented by the formula (III), m in the formula (III) is a number of from 1 to 6.

When X is an amide alkylene group represented by the formula (JV), R ² in the formula (IV) is an alkylene group having 2 to 8 carbon atoms, and the alkylene group may be linear or branched. Among them, those in which R ² is a branched alkylene group are preferable because of being easily available. Even more, in the monomer units represented by the formula (I), X in the formula (I) is a group represented by any one of the following formulas (V) to (VII):

GHr ₃

— G - N - C - C H ₂ - / _V x

Ii H i ^κ

O ^π CH.

C - N - CH — (VI) O ^π C ₂ H ₅

, and

C - N - CH ₂ - CH - CH ₂ — π H i (VII)

O CH,

is preferable because of its excellent polymerizability. Even more, in the monomer units represented by the formula (I), X in the formula (I) is a group represented by the formula (V) is preferable because the material is highly widely used, and very excellent polymerizability.

Among the monomer units represented by the formula (I), those in which R ¹ in the formula (I) is a hydrogen atom, and X is an amide alkylene group represented by the formula (V) are even more preferable, from the viewpoint of not only polymerizability and availability of the material, but also smoothness of clothes after polymerization into the sulfonic acid-based polymer, and redeposition preventing property against soil particles.

The monomer unit represented by the formula (I) in the above-mentioned constituting monomers may all be in the form of an acid, or an entire part or a part thereof may be a neutralized salt form. When a part or an entire part of the monomer unit represented by the formula (I) in the constituting monomers is in a neutralized salt form, a counterion for neutralizing the sulfonate residue is preferably a monovalent cation. More specifically, the counterion is preferably an alkali metal ion, among which neutralized salt forms of Na or K salt are even more preferable.

As the constituting monomers other than the monomer unit represented by the formula (I), an optional vinyl comonomer can be used for copolymerization

taking careful note not to impair the effects of the present invention.

The comonomer that can be used in the present invention includes acrylic acid, methacrylic acid, acrylamide, N-vinylacetamide, a maleic acid-based monomer (maleic anhydride, maleic acid, maleic acid monoester, maleic acid monoamide, or a mixture composed of two or more kinds of these) and salts thereof, itaconic acid and salts thereof, and the like. One or more kinds of these may be contained, as a comonomer, or they may not be contained. Preferred comonomers include those having high copolymerizability with the monomer unit represented by the formula (I), and for example, acrylic acid or a salt thereof is more preferred as a comonomer constituting the sulfonic acid-based polymer of the present invention. In the present invention, the acrylic acid or a salt thereof is contained in a molar ratio of the acrylic acid or a salt thereof to the sulfonic acid-based polymer of preferably 30% by mol or less, more preferably 20% by mol or less, even more preferably 10% by mol or less, and even more preferably 5% by mol or less, from the viewpoint of redeposition preventing property of soil particles. For example, comonomers composed of 70 to 100% by mol of the monomer units represented by the formula (I) and 0 to 30% by mol of acrylic acid or a salt thereof are preferable for the sulfonic acid-based polymer usable in the present invention. When the sulfonic acid-based polymer in the present invention contains acrylamide as a constituting comonomer, the molar ratio of acrylamide to the sulfonic acid-based polymer is preferably 10% by mol or less, more preferably 8% by mol or less, even more preferably 6% by mol or less, and even more preferably 4% by mol or less, from the viewpoint of redeposition preventing property of soil particles.

In addition, the sulfonic acid-based polymer contains N-vinylacetamide as a constituting comonomer, the molar ratio of N-vinylacetamide to the sulfonic acid-based polymer is preferably 10% by mol or less, more preferably 8% by mol or less, even more preferably 6% by mol or less, and even more preferably 4% by mol or less, from the viewpoint of redeposition preventing property of soil particles.

The sulfonic acid-based polymer exhibits smoothness that gives pleasant experience during hand-washing. From the viewpoint of this effect, the sulfonic acid-based polymer has a weight-average molecular weight of 1,000,000 or more. The weight-average molecular weight is preferably 1,200,000 or more, more preferably 1,500,000 or more, even more preferably 2,000,000 or more, even more preferably 3,000,000 or more, even more preferably 5,000,000 or more, even more preferably 6,000,000 or more, from the viewpoint of imparting high level of smoothness to the laundry clothes. In addition, the weight-average molecular weight is 30,000,000 or less, preferably 25,000,000 or less, and more preferably 20,000,000 or less, from the viewpoint of availability.

The molecular weight is determined by gel permeation chromatography (hereinafter referred to as GPC method) under the following determination conditions, in which the molecular weight calculated as polyethylene oxide (PEO) is defined as a found value.

[Determination Conditions for GPC Method]

The column used is PW/GMPWXL/GMPWXL (manufactured by Tosoh Corporation), the eluent used is 0.2 M phosphate buffer (KH ₂ PO ₄ , Na ₂ HPO ₄ , pH = 7)/CH ₃ CN = 9/1 (weight ratio), the column temperature is 40 ⁰ C, the flow

rate is 1.0 mL/min, and the sample concentration is from 10 to 100 μg/mL. The detector used is RALLS (Right Angle Laser Light Scattering).

In order to obtain sufficient smoothness upon hand-washing, it is preferable that the ratio of the sulfonic acid-based polymer in the entire detergent composition, on the basis of the overall detergent after mixing the sulfonic acid- based polymer containing particles composed of the polymer, is 0.05% by weight or more, preferably 0.1% by weight or more, more preferably 0.3% by weight or more, even more preferably 0.5% by weight or more, even more preferably 0.8% by weight or more, even more preferably 1.0% by weight or more, and even more preferably 1.2% by weight or more. In addition, it is preferable that the ratio of the sulfonic acid-based polymer in the entire detergent composition is 10% by weight or less, preferably 8% by weight or less, more preferably 5% by weight or less, even more preferably 4% by weight or less, even more preferably 3.5% by Weight or less, even more preferably 3% by weight or less, and even more preferably 2.5% by weight or less, from the viewpoint of imparting an appropriate feel upon hand-washing. Furthermore, the ratio of the sulfonic acid-based polymer in the present invention to the entire detergent composition, on the basis of the overall detergent composed of the polymer, is preferably from 0.05 to 10% by weight or less, more preferably from

0.1 to 8% by weight, even more preferably from 0.3 to 5% by weight, even more preferably from 0.5 to 4% by weight, and even more preferably from 1.2 to 3% by weight, from the viewpoint of having sufficient and appropriate level of smoothness upon hand-washing. In addition, when the particles containing the sulfonic acid-based polymer

are used as a detergent additive, it is preferable that the amount of the polymer used upon washing is the same as the ratio of the sulfonic acid-based polymer in the present invention in the entire detergent composition mentioned above. The process for preparing a sulfonic acid-based polymer used in the present invention is not particularly limited. The sulfonic acid-based polymer as described above includes cross-linked polymer and ήon-cross-linked polymer. The lower the degree of cross-linking, the more favorable the exhibition of the smoothness. Even in the preparation process, a process less likely to generate the formation of a branched structure and/or cross-linked structure is more preferable.

The sulfonic acid-based polymer used in the present invention can be prepared by a method such as a radical polymerization method, an anionic polymerization method, or a cationic polymerization method.

When the sulfonic acid-based polymer is prepared by a radical polymerization method, as a radical polymerization initiator, a peroxide initiator such as potassium persulfate, ammonium persulfate, sodium persulfate, t-butyl hydroperoxide, or hydrogen peroxide may be used, or an azo-based initiator such as 2,2'-azobis(2-amidinopropane) dihydrochloride may be used, or these initiators may be used together with a reducing agent such as sodium sulfite, sodium hydrogensulfite, ferrous sulfate, or L-ascorbic acid as a redox initiator, or polymerization may be initiated by irradiating ultraviolet rays, electron beams, γ-rays, or the like. Here, the amount of these polymerization initiators used is preferably from 0.0001 to 5% by mol, more preferably from 0.001 to 1.5% by mol, and even more preferably from 0.01 to 0.5% by mol, based on the monomers used in the polymerization or copolymerization.

In addition, when the sulfonic acid-based polymer is prepared by an anionic polymerization method, as a polymerization initiator, an aromatic complex of an alkali metal, such as naphthyl sodium; an alkali metal such as lithium, sodium or potassium; or an organolithium compound (alkyllithium compound), such as n-butyllithium, t-butyllithium, methyllithium, or fluorenyllithium may be used, or an organomagnesium compound, preferably a Grignard reagent, such as phenylmagnesium bromide or butylmagnesium bromide, or a diorganomagnesium compound such as dibenzylmagnesium, dibutylmagnesium, or benzylpicolylmagnesium may be used. Here, the amount of these polymerization initiators used is preferably from 0.0001 to 5% by mol, more preferably from 0.001 to 1.5% by mol, and even more preferably from 0.01 to 0.5% by mol, based on the monomers used in the polymerization or copolymerization.

On the other hand, when the sulfonic acid-based polymer is prepared by a cationic polymerization method, as a polymerization initiator, a Brønsted acid such as trifluoroacetic acid, trichloroacetic acid, sulfuric acid, methanesulfonic acid, or trifluoromethanesulfonic acid, or a Brønsted acid/Lewis acid mixture such as water/boron trifluoride, water/boron trichloride, water/aluminum chloride, water/aluminum bromide, water/tin tetrachloride, trichloroacetic acid/tin tetrachloride, hydrogen chloride/boron trichloride, or hydrogen chloride/aluminum trichloride may be used, or an organic cation such as a trityl cation or a tropylium cation, a mixture generating oxocarbonium ion such as acetyl chloride/silver hexafluoroantimonate or acetyl chloride/silver perchlorate may be used. Here, the amount of these polymerization initiators used is preferably from 0.0001 to 5% by mol, more preferably from 0.001 to 1.5% by

mol, and even more preferably from 0.01 to 0.5% by mol, based on the monomers used in the polymerization or copolymerization.

As the polymerization method for obtaining the sulfonic acid-based polymer usable in the present invention, bulk polymerization method or precipitation polymerization method can also be carried out. However, an aqueous solution polymerization method or a reverse phase suspension polymerization method is preferable, from the viewpoint of being able to obtain a polymer having a higher level of smoothness, and facilitating the control of the polymerization.

< Sulfonic Acid-Based Polymer-Containing Particles >

The sulfonic acid-based polymer-containing particles usable in the powder detergent composition of the present invention, or usable in the detergent additive make up a detergent composition together with base detergent particles containing an anionic surfactant, a builder for capturing a water-hardness component, and an alkaline substance, and smoothness is exhibited by introducing the detergent composition into water to dissolve. Therefore, in order to exhibit smoothness, it is preferable to dissolve the detergent composition within a given washing time. On the other hand, the redeposition preventing property of soil particles can be improved in the case where the dissolution of the sulfonic acid-based polymer-containing particles is slowly or gradually progressed, as compared to that of the base detergent particles containing an anionic surfactant, a builder for capturing a water-hardness component, and an alkaline substance. In other words, it is preferable that the sulfonic acid-based polymer containing particles have delayed dissolution speed relative to the base

detergent particles, while having sufficient particle dissolubility in the detergent application. As described above, a process of obtaining sulfonic acid-based polymer-containing particles having a preferred dissolution speed includes a process including the step of further adjusting a molecular weight of the sulfonic acid-based polymer from the above-mentioned preferred range to a more specified one; a process including the step of adjusting a particle size of the sulfonic acid-based polymer-containing particles; a process including the step of treating the surface of the particles; a process including the step of controlling dissolution of overall particles constituting the particles together with the sulfonic acid-based polymer by carefully studying the kinds and the amounts of the components other than the sulfonic acid-based polymer; and the like. Among them, as the process of obtaining sulfonic acid-based polymer-containing particles having a preferred dissolution speed, the process of adjusting a molecular weight of the sulfonic acid-based polymer and the process of adjusting a particle size of the sulfonic acid-based polymer-containing particles are preferable, from the viewpoint of simplified preparation steps.

A process of obtaining sulfonic acid-based polymer-containing particles having a preferred particle size is not particularly limited, and any method can be employed as long as the method is capable of obtaining particles having particle sizes so as to give the preferred dissolution speed as mentioned above. The process of obtaining sulfonic acid-based polymer-containing particles having a preferred particle size includes, for example, a process including the step of fractionating the particles using sieves; a process including the step of tumble- drying and granulating the particles while spraying an aqueous polymer solution by means of drying in a fluidized bed or the like; in a case where the polymer is

polymerized in a reverse phase suspension system, in the polymerization steps, the process includes the steps of adjusting dispersion system of the suspension system the site at which the polymerization is carried out and/or agitation blades or agitation conditions such as agitation rates, and controlling the particle size and the particle size distribution of the formed polymer particles; and a process combining these processes. Among them, the particle size control in the stage of the polymerization of the polymer is preferable, from the viewpoint of not necessitating a new step, or from the viewpoint of not wastefully using the polymer, or the like. As the sulfonic acid-based polymer-containing particles used for the powder detergent composition of the present invention, or the detergent additive, those obtained as particles having a high content of the polymer as in the case of the above-mentioned reverse phase suspension polymerization have an average particle size of 500 μm or less, preferably 400 μm or less, more preferably 350 μm or less, even more preferably 300 μm or less, from the viewpoint of not generating remnants of the particles upon washing.

Further, the above-mentioned average particle size is preferably 50 μm or more, more preferably 70 μm or more, even more preferably 90 μm or more, and even more preferably 110 μm or more, from the viewpoint of having mild dissolution and excellent redeposition preventing property of the soil particles.

The above-mentioned average particle size is preferably from 50 to 500 μm, more preferably from 70 to 400 μm, even more preferably from 90 to 350 μm.

In addition, even if the particles have the same average particle size, if the proportion of an even finer portion is smaller in the distribution of the fraction

positioned in the finer side than the average particle size, the dissolution of the overall particles is even milder. From this viewpoint, the sulfonic acid-based polymer-containing particles usable in the powder detergent composition of the present invention, or usable in the detergent additive have a content of 63 μm sieve-pass particles of preferably 20% by weight or less, more preferably 15% by weight or less, even more preferably 10% by weight or less, even more preferably 5% by, weight or less.

On the other hand, even if the particles have the same average particle size, if the proportion of the fraction having coarse particle sizes is smaller, the remnants of the particles are not generated upon washing. From this viewpoint, the sulfonic acid-based polymer-containing particles usable in the powder detergent composition of the present invention, or usable in the detergent additive have a content of 1,400 μm sieve-on particles of preferably 10% by weight or less, more preferably 8% by weight or less, even more preferably 6% ^< by weight or less, even more preferably 4% by weight or less, even more preferably 2% by weight or less.

Determination Methods for Particle Size and Particle Size Distribution

Twelve-step sieves each having a sieve-opening of 2,000 μm, 1,400 μm, 1,000 μm, 710 μm, 500 μm, 355 μm, 250 μm, 180 μm, 125 μm, 90 μm, 63 μm, and 45 μm, and a receiving tray were used, and the sieves and the receiving tray were attached to a rotating and tapping shaker machine (manufactured by HEIKO SEISAKUSHO). A 100 g sample was vibrated for 10 minutes to be classified (tapping: 156 times/min, rolling: 290 times/min). Thereafter, the weight of the particles remaining on the receiving tray, and each of the sieves

was determined. When a sieve-opening of a first sieve of which cumulative weight ratio counted from fine particle side is 50% or more is defined as a μm, a sieve-opening of one step larger than a μm is defined as b μm, a cumulative weight ratio from the receiving tray to the a μm-sieve is defined as c%, and a mass weight ratio on the a μm-sieve is defined as d%, the average particle size can be calculated according to the following formula:

(Average Particle Size) = 10 ^A wherein A satisfies the formula:

A = (50 - (c-d/(log b - log a) x log b))/(d/(log b - log a)).

(Content of 63 μm Sieve-Pass Particles) = Weight ratio of 45 μm sieve-on particles + weight ratio on the receiving tray

(Content of 1,400 μm Sieve-on Particles) = Ratio of total weights of 2,000 μm sieve-on particles and 1,400 μm sieve-on particles The sulfonic acid-based polymer-containing particles may contain one or more components other than the sulfonic acid-based polymer in an amount within the range so as not to inhibit the effects of the present invention, or these components may not be contained.

Those components that are carried over from the step of polymerizing the sulfonic acid-based polymer, including, for example the unreacted monomer, the polymerization initiator, the dispersant, the solvent, and a micro-component such as a side product caused therefrom, or water or the like are not particularly limited so long as the effects of the present invention are not lost.

Originally, the sulfonic acid-based polymer is contained in the sulfonic acid-based polymer-containing particles preferably at a high content, more

preferably 70% by weight or more, even more preferably 75% by weight or more, even more preferably 80% by weight or more, even more preferably 85% by weight or more, even more preferably 90% by weight or more, from the viewpoint of reducing the amount as the particles. In the case of a sulfonic acid- based polymer having a weight-average molecular weight of 1,000,000 or more, the higher the content of the polymer in the particles, the milder the dissolution speed, so that the particles having an even higher content are excellent from the viewpoint of redeposition preventing property of soil particles.

Here, in the process of powder-mixing the sulfonic acid-based polymer containing particles in the present invention and the base detergent particles, the following procedures may be carried out in some cases in order to aim for increase in measurement accuracy or the like, for the purpose of accurately mixing the both components or the like, according to a defined ratio set for both the components. For example, the sulfonic acid-based particles to be added and mixed in a small amount may be mixed with third particles to dilute the particles and used; other components may be added upon preparation of the sulfonic acid- based polymer-containing particles, or the content of the polymer may be diluted. Even more, in the case where the content of the polymer is diluted, although the content of the polymer in the sulfonic acid-based polymer-containing particles would be lowered, such a process may be arbitrarily carried out as long as the inherent effects of the present invention are not inhibited.

< Base Detergent Particles >

The base detergent particles usable in the powder detergent composition of the present invention at least contains an anionic surfactant, and preferably

further contains a builder for capturing a water-hardness component and an alkaline substance. The base detergent particles alone may contain necessary kinds and amounts of detergent base materials for exhibiting the minimal functions as the laundry detergent, or one or more components may be needed to be added to function as a laundry detergent.

In order to obtain the effects of the present invention, the base detergent particles that are μsed together with the sulfonic acid-based polymer-containing particles have high dissolubility.

Since the base detergent particles have a fast dissolution speed, the base detergent particles have an average particle size of preferably 600 μm or less, more preferably 550 μm or less, even more preferably 500 μm or less, even more preferably 450 μm or less, even more preferably 400 μm or less.

Also, the base detergent particles have an average particle size of preferably 100 μm or more, more preferably 125 μm or more, even more preferably 150 μm or more, even more preferably 175 μm or more, even more preferably 200 μm or more, from the viewpoint of physical properties of the powder.

In addition, the base detergent particles have an average particle size in a range of preferably from 100 to 600 μm, more preferably from 125 to 550 μm, even more preferably from 150 to 500 μm, even more preferably from 175 to 450 μm, even more preferably from 200 to 400 μm.

The particle size is determined using a rotating and tapping shaker machine in the same manner as in the sulfonic acid-based polymer-containing particles. A process for preparing the base detergent particles is not particularly

limited, as long as the process is a known process such as spray-drying method, or tumbling granulation method. Among them, since hollow particles are easily formed in the spray-drying method, the spray-drying method is listed as a preferred, preparation process, from the viewpoint of a sufficiently fast dissolution speed of the base detergent particles.

In addition, since the base detergent particles usable in the powder detergent composition of the present invention have a fast dissolution speed, the base detergent particles have a bulk density as determined by a method prescribed in JIS K3362 of preferably 1.0 or less, more preferably 0.9 or less, even more preferably 0.8 or less, even more preferably 0.7 or less, and even more preferably 0.65 or less. On the other hand, it is preferable that the powder detergent composition has a high bulk density, from the viewpoint of distribution aptitude such as ease in carrying, ease in storing, or ease in measuring the powder detergent composition as a commercial product at a distribution stage or a situation of actual use of a consumer, and ease in use. The powder detergent composition has a bulk density of preferably 0.25 or more, more preferably 0.3 or more, even more preferably 0.4 or more, and even more preferably 0.45 or more. The bulk density is even more preferably from 0.3 to 0.9, and even more preferably from 0.4 to 0.8.

< Anionic Surfactant >

The anionic surfactant usable in the process for washing and the powder detergent composition of the present invention includes those having an anionic hydrophilic group having a sulfuric acid-based or sulfonic acid-based structure, such as alkylbenzenesulfonates, salts of higher alcohol sulfuric esters, salts of α-

olefinsulfonic acids, salts of short-chained alkyl esters of α-sulfofatty acids, and salts of polyalkoxylated higher alcohol sulfuric esters. Even more preferably the preferred anionic surfactant in the present invention includes an alkylbenzenesulfonate, from the viewpoint of economic advantage and its wide use.

The anionic surfactant is contained in the detergent composition of the present invention in an amount of preferably 8% by weight or more, more preferably 10% by weight or more, even more preferably 12% by weight or more, even more preferably 14% by weight or more, even more preferably 16% by weight or more, and even more preferably 18% by weight or more, from the viewpoint of detergency and foamability.

On the other hand, for the purposes of securing the compositional freedom of the overall composition and avoiding excessive foaming, the anionic surfactant is contained in the overall detergent composition in an amount of preferably 50% by weight or less, more preferably 45% by weight or less, even more preferably 40% by weight or less, even more preferably 37% by weight or less, and even more preferably 35% by weight or less.

The anionic surfactant is contained in the powder detergent composition that is usable for the process for washing and the powder detergent composition in an amount of from 8 to 50% by weight, more preferably from 10 to 45% by weight, even more preferably from 12 to 40% by weight, even more preferably from 14 to 37% by weight, and even more preferably from 16 to 35% by weight.

< Alkylbenzenesulfonate > The alkylbenzenesulfonate used in the present invention includes a hard-

type alkylbenzenesulfonate of which alkyl moiety has a branched structure, a soft-type alkylbenzenesulfonate of which alkyl moiety has a linear structure, and the like. It is preferable that the alkylbenzenesulfonate is linear (soft-type), from the viewpoint of biodegradability. The alkylbenzenesulfonate is obtained by sulfonating an alkylbenzene. In this case, the alkylbenzene serving as a raw material may be prepared by various preparation processes. The content of phenyl isomer differs depending upon the preparation processes, and the content affects the physical properties as a surfactant after being derived to an alkylbenzenesulfonate. An alkylbenzenesulfonate in which an alkylbenzene prepared by α-olefin method is used as a raw material is preferable from the viewpoint of detergency and productivity.

In addition, alkylbenzenesulfonates such as methyl-branched alkyl-type alkylbenzenesulfonate or methyl-substituted benzene-type alkylbenzenesulfonate can be preferably used, from the viewpoint of detergency and resistance to hard- water.

The alkylbenzenesulfonate is obtained by sulfonating the above- mentioned alkylbenzene with a sulfurous gas or a fumed sulfuric acid, and neutralizing the product with an alkaline component such as sodium hydroxide or potassium hydroxide. The used salt is not particularly limited, so long as the salt is a monovalent cation, such as an alkali metal salt such as a lithium salt, a potassium salt, or a sodium salt, as well as an ammonium salt or an amine salt. The salt of an alkaline earth metal such as calcium or magnesium is preferably used in an amount as little as possible, because the salt has a function of precipitating the alkylbenzenesulfonic acid. As to the counterion, the alkali metal salt is preferable, from the viewpoint of storage stability and costs, among

which a sodium salt is more preferable.

The alkylbenzenesulfonate used in the process for washing and the powder detergent composition of the present invention is formulated within the range listed above, as the above-mentioned anionic surfactant.

< Builder for Capturing Water-Hardness Component >

The builder for capturing a water-hardness component used in the present invention is formulated for the purpose of capturing a multivalent metal cation such as Ca ²⁺ or Mg ²⁺ in a washing water that inhibits the deterging action or the like by a surfactant, thereby improving detergency.

Preferred examples of the builder for capturing a water-hardness component in the present invention include crystalline aluminosilicates such as zeolites type- A, type-X, type- Y, and type-P; condensed phosphates such as tripolyphosphates and pyrophosphates; and water-soluble organic acid salts represented by low-molecular weight carboxylates such as citrates and fύmarates.

As the water-soluble organic acid salts, those base materials having a large cationic exchange capacity and/or pK _Ca are preferable, and more specifically, the water-soluble organic acid salts are preferably methyliminodiacetates, iminodisuccinates, ethylenediaminedisuccinates, taurine diacetates, hydroxyethyl iminodiacetates, β-alanine diacetates, hydroxyiminodisuccinates, methylglycine diacetates, glutamate diacetates, asparagine diacetates, serine diacetates, and the like, from the viewpoint that high detergency can be expected.

Among these builders for capturing a water-hardness component, the condensed phosphates, crystalline aluminosilicates and mixtures thereof are preferable from the viewpoint of economic advantage.

The condensed phosphate is preferable because the condensed phosphate can be easily formulated in an aqueous slurry when the detergent particles are prepared by spray-drying of the aqueous slurry. Even more, the tripolyphosphate is preferable, from the viewpoint of having a high cationic exchange capacity. An even more preferred condensed phosphate is sodium tripolyphosphate.

The crystalline aluminosilicate is preferable from the viewpoint of exhibiting the action as the aid for formation of preparations, such as surface modifications of the detergent particles, or as a physical property-modifying agent. An even more preferred crystalline aluminosilicate is zeolite type-A, and among them, those of which primary particles have an average particle size of from 0.5 to 10 μm are preferable from the viewpoint of ability of capturing a water-hardness component and/or ability of modifying physical properties of the particles.

The builder for capturing a water-hardness component used in the process for washing and the powder detergent composition of the present invention is contained in the powder detergent composition in an amount of preferably 5% by weight or more, more preferably 8% by weight or more, even more preferably 10% by weight or more and even more preferably 12% by weight or more, from the viewpoint of securing sufficient capacity of capturing water-hardness. In addition, the builder for capturing a water-hardness component is contained in the powder detergent composition in an amount of preferably 50% by weight or less, more preferably 40% by weight or less, even more preferably 35% by weight or less, even more preferably 30% by weight or less, and even more preferably 25% by weight or less, from the viewpoint of securing the compositional freedom of the overall detergent composition including other

detergent base materials. Further, the amount of the builder for capturing a water-hardness component in the overall detergent composition is preferably from 5 to 40% by weight, more preferably from 8 to 35% by weight, and even more preferably from 10 to 30% by weight.

< Alkaline Substance >

The alkaline substance used in the present invention is not particularly limited, and a known alkaline substance can be used. The alkaline substance of the present invention refers to a group of compounds for elevating a pH of a washing water, in which a deterging effect is obtained in a deterging system by having an action of saponifying dirt stains (even more preferably, a fatty acid), thereby self-emulsifying or self-dispersing the dirt stains, to remove and detach the dirt stains from the substrate or the like.

The alkaline substance includes hydroxides, carbonates, hydrogencarbonates, silicates, and the like. The counterion includes an alkali metal ion such as lithium, potassium or sodium.

Since the alkaline substance usable in the present invention plays a significant role in buffering the detergent system in a pH range suitable for washing, as the alkaline substance, a weak acid-strong basic salt is preferable, and as the inorganic compound, a carbonate, a hydrogencarbonate, a silicate and a mixture thereof are preferable. Although the counterion is not particularly limited, a potassium salt or a sodium salt is preferable, and a sodium salt is more preferable, from the viewpoint of storage stability or costs, or enhancing ionic strength of a washing liquid, thereby favorably acting on detergency against sebum dirt stains, and the like.

Sodium carbonate, sodium hydrogencarbonate, sodium silicate, and a mixture thereof are even more preferably used as an alkaline substance, from the viewpoint of having a preferred buffering pH value range, a high deterging effect, and economic advantages. The alkaline substance usable in the process for washing and the powder detergent composition of the present invention is contained in the powder detergent composition in an amount of preferably 7% by weight or more, more preferably 8% by weight or more, even more preferably 10% by weight or more, even more preferably 12% by weight or more, even more preferably 15% by weight or more, from the viewpoint of obtaining a high deterging effect. In addition, the alkaline substance is contained in an amount of 40% by weight or less, preferably 35% by weight or less, more preferably 31% by weight or less, even more preferably 27% by weight or less, from the viewpoint of skin irritability or safety to an individual who hand-washes during hand-washing. The alkaline usable in the process for washing and the powder detergent composition of the present invention is contained in the powder detergent composition in a more preferred range of from 7 to 40% by weight, preferably from 8 to 35% by weight, more preferably from 10 to 31% by weight, even more preferably from 12 to 27% by weight.

< Other Detergent Components >

As other detergent components usable in the present invention, optional components can be formulated so long as the effects of the present invention are not lost.

(Other Surfactants)

In the process for washing and/or the detergent composition of the present invention, as a surfactant other than the anionic surfactant, a cationic surfactant, a nonionic surfactant, an amphoteric surfactant or the like may be contained. Examples of the cationic surfactant include monoalkylammonium quaternary salts, dialkylammonium quaternary salts, and the like

Examples of the nonionic surfactant includes polyoxyethylene alkyl ethers, polyoxyethylene-polyoxypropylene alkyl ethers, polyoxyethylene- polyoxypropylene glycols as represented by Pluronic (trade name), polyoxyethylene alkylamines, higher fatty acid alkanolamides, polyoxyalkylene higher fatty acid alkanolamides, alkylglucosides, alkylglucosamides, alkylamine oxides, higher fatty acid alkylene diamine-N-amide-N'-dialkyl oxides, and the like.

Examples of the amphoteric surfactant include betaine, amidepropylbetaine, sulfobetaine, and the like.

(Dispersion System)

The process for washing and/or detergent composition of the present invention may include an optional dispersion system. The dispersion system includes polyethylene glycols; polycarboxylic acid-based polymers; polyvinyl alcohols; polyvinyl pyrrolidone; and cellulose-based dispersants such as carboxymethyl cellulose, hydroxypropylmethyl cellulose, hydroxybutylmethyl cellulose, hydroxyethyl cellulose; and mixed systems thereof.

(Enzyme)

In the process for washing and/or detergent composition of the present invention, the detergent components may include an optional enzyme. The enzyme includes protease, lipase, cellulase, amylase, mannanase, and the like. Further, a combined use of cellulase and protease is preferable from the viewpoint of detergency.

(Fluorescent Brightener)

In the process for washing and/or detergent composition of the present invention, the detergent components may include an optional fluorescent brightener. The fluorescent brightener includes biphenyl-type fluorescent brighter and aminostilbene-type fluorescent brighter.

(Bleaching System)

In the process for washing and/or detergent composition of the present invention, the detergent components may include an optional bleaching system for the purpose of reinforcing the function of recovering dirt stains or recovering yellowing of clothes. As the bleaching system, an oxygen-based bleaching system that is less likely to cause discoloration or fading of dyes on colored clothes is preferable. The bleaching system as described above includes a system including a peroxide compound as represented by sodium percarbonate or sodium perborate as a hydrogen peroxide-generating source; a bleaching system further containing a bleaching activation species as represented by an organic peracid precursor, such as tetraacetylethylenediamine, nonanoyloxybenzene sulfonate, or decanoyloxybenzene sulfonate; and the like.

(Other Components)

In the process for washing and/or detergent composition of the present invention, the detergent components may include an inorganic salt such as a sulfate in, order to adjust ionic strength of the washing liquid. Even more, an inexpensive sodium sulfate is preferably used, because a function of a particle- forming agent, a filler, or the like can be exhibited.

In addition, in the detergent components, a sulfite, a thiosulfate or the like may be used as a reducing agent of an active chlorine that can exist in tap water; white carbon or an amorphous silica compound may be used as a surface- modifying agent of detergent particles; a clay mineral such as bentonite or the like may be used as a laundry softening agent utilizing a solid lubricating action.

EXAMPLES

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 present invention.

Disclosure of Test Method

< Evaluation of Redeposition Preventing Property of Detergent > Unless specified otherwise, the evaluation of redeposition preventing property of a detergent composition was made in accordance with the following method.

To a beaker containing 1,000 mL of water used (CaCl ₂ : 55.42 mg/L,

MgCl ₂ ^» 6H ₂ O: 43.51 mg/L) at 20°C was added 2.5 g of soil particles (Kanuma red clay for gardening, having a size of passing a sieve opening of 200 mesh

[purchased from K.K. Kokukoen (10, Yoshimasa-cho, Izumi-shi, Osaka)]), and the mixture was homogeneously dispersed. Thereafter, this dispersion was transferred to a sample cup attached to Terg-O-Tometer at 20 ⁰ C. Next, 5.0 g of a detergent composition and 5 pieces of cotton calico of 6 cm x 6 cm (#2023 calico, standard product selected by Nippon Yukagaku Kyokai, sold by Sentaku

Kagaku Kyokai) were introduced into the Terg-O-Tometer at one time, and immediately stirred at a rotational speed of 100 ± 5 r/min for 10 minutes, and a washing procedure was carried out. After the termination of the washing procedure, the cotton calico that was taken out was lightly hand-squeezed so as to have a water content of 200% by weight or less. The calico was placed in

1,000 mL of water used (CaCl ₂ : 55.42 mg/L, MgCl ₂ ^« 6H ₂ O: 43.51 mg/L) at 20 ⁰ C, and rinsed for 3 minutes with the Terg-O-Tometer (rotational speed: 100 ± 5 r/min) for 3 minutes. The rinsing procedures were carried out for a total of 2 times. Next, the calico that was taken out was air-dried, and thereafter finished by ironing. Thereafter, the reflectance of the obtained calico at 460 nm was determined (spectrophotometer, manufactured by Nihon Denshoku Kogyo K.K.). The redeposition preventing ratio was obtained by the following formula, and evaluated in accordance with the following evaluation criteria.

Redeposition (Reflectance of Cotton Calico After Test)

Preventing Ratio = x 100

(%\ (Reflectance of Cotton Calico Before Test)

< Method for Evaluating Smoothness >

An 8.2 L polypropylene washtub (commercially available from YAZAKI) having a diameter of 30 cm and a depth of 13 cm was charged with 2 L of hard

water (Ca/Mg molar ratio: 7/3) corresponding to 8.9 mg CaCO ₃ ZL, temperature- controlled to 25°C, and 15 g of a detergent composition was supplied into the water, and the water was continued to be stirred by hand with a vigorousness to an extent that the water was not spilled from the washtub. After 30 seconds from the beginning of stirring, a piece of 100% cotton T-shirts (white, commercially available from Gunze, L size) was soaked in the washing liquid in the washtub so that the entire T-^hirt was sufficiently soaked. Five minutes thereafter, the breast portions of the T-shirt were held with both hands, and the breast portions of the T-shirt were rubbed against each other. The portions were rubbed together upon taking the shirt out of the washing liquid. After rubbing together for every 3 to 5 times, the rubbed portions were temporarily soaked in the washing liquid. The ease in rubbing when the portions were rubbed together was judged in Ranks 1 to 5 as to smoothness. When this evaluation was carried out only with the water prepared above, the wrinkles of the T-shirt hindered the smoothness, the portions to be rubbed together were hardly rubbed because there were no bubbles in the portions rubbed together, so that the smoothness worsened. In such a case, the smoothness was defined to have a rank of 1. The state of each rank is as shown below.

Rank 1: very low smoothness and some feel of squeakiness, thereby making it very difficult to perform hand-washing.

Rank 2: low smoothness and some feel of squeakiness, thereby not being easy to perform hand-washing.

Rank 3: smoothness being medium level, and being capable of performing hand-washing without squeakiness. Rank 4: smoothness being high, being capable of performing hand-

washing more easily without squeakiness.

Rank 5: smoothness being very high, being capable of performing hand- washing very easily without squeakiness.

Incidentally, in the above test, an average value of the results of evaluation made by 6 expert panelists was obtained to provide a evaluation score.

< Method for Evaluating Dissolubility>

One-thousand milliliters of tap water temperature-adjusted to 10 ⁰ C and a stirrer made of a fluororesin having a diameter of about 8 mm and a length of about 35 mm were placed in a 1 L beaker, and stirred using a magnetic stirrer

(commercially available from Shimadzu Corporation under a trade name Model SST-172) so as to maintain an indicated value of a rotational speed of 800 ± 10 r/min. Thereto was supplied 1 g of a detergent composition, and the stirring was continued for another 10 minutes after supplying the detergent composition. After the termination of stirring, the water inside the beaker is filtered with a wire gauze having a sieve opening of 200 mesh, to collect the residue. The residue obtained was dried under the conditions of 105 ⁰ C for 30 minutes together with the wire gauze, and the weight of the residue was obtained from the previously measured weight of the wire gauze and the total weight of the wire gauze and the residue after drying. A water-insoluble content [%] was calculated by the following formula.

Water-Insoluble (Weight of Residue)

X lOO

Content [%] (Weight of Test Detergent)

Preparation Examples of Sulfonic Acid-Based Polymer-Containing Particles

Preparation Example 1

The amount 6.00 g of a sugar ester (commercially available from Mitsubishi Chemical Foods K.K. under the trade name of "S-770") was dissolved in 800 g of hexane, and the solution was heated to 70 ⁰ C under a nitrogen atmosphere. To the heated solution was added dropwise over a period of 1 hour a solutipn prepared by dissolving 600 g of 2-acrylamide-2- methylpropanesulfonic acid, 160 g of sodium hydroxide, 10 g of acrylic acid, and 3.0 g of 2,2'-azobis(2-methylpropionamidine) dihydrochloride (commercially available from Wako Pure Chemical Industries, Ltd. under the trade name of "V-50") in 510 g of ion-exchanged water, and the mixture was dispersed, and stirred for an additional 30 minutes. The mixture was subjected to azeotropic dehydration under reflux, and only a water phase from the azeotropic reflux was separated away. The mixture was allowed to cool at a point where a water content was reduced to 30% by weight, and the resulting solid granular product was sufficiently dried under a reduced pressure, to give 672 g (99.4%) sulfonic acid-based polymer-containing particles A in the form of colorless granules.

The polymer of the particles A had a weight-average molecular weight of 5,000,000, as determined by the method described in the present invention. In addition, the particles A had an average particle size of 197 μm, a content of particles having a size of 63 μm sieve-passed of 0.7% by weight, and a content of particles having a size of 1400 μm sieve-on of 0.6% by weight.

Preparation Example 2

The amount 6.00 g of a sugar ester (commercially available from Mitsubishi Chemical Foods K.K. under the trade name of "S-770") in 800 g of hexane, and the solution was heated to 70 ⁰ C under a nitrogen atmosphere. To the heated solution was added dropwise over a period of 1 hour a solution prepared by dissolving 622 g of 2-acrylamide-2-methylpropanesulfonic acid,

160 g of sodium hydroxide and 24 g of 2,2'-azobis(2-methylpropionamidine) dihydrochloride (commercially available from Wako Pure Chemical Industries, Ltd. under the trade name of "V-50") in 510 g of ion-exchanged water, and the mixture was dispersed, and stirred for an additional 30 minutes. The mixture was subjected to azeotropic dehydration under reflux, and only a water phase from the azeotropic reflux was separated away. The mixture was allowed to cool at a point where a water content was reduced to 30% by weight, and the resulting solid granular product was sufficiently dried under a reduced pressure, to give 681 g (99.0%) sulfonic acid-based polymer-containing particles G in the form of colorless granules.

The polymer of the particles G had a weight-average molecular weight of 1,200,000, as determined by the method described in the present invention. In addition, the particles G had an average particle size of 145 μm, a content of particles having a size of 63 μm sieve-passed of 1.6% by weight, and a content of particles having a size of 1400 μm sieve-on of 0.5% by weight.

Preparation Example 3

The same procedures as in Preparation Example 2 were carried out except that the amount of 24 g of 2,2'-azobis(2-methylpropionamidine) dihydrochloride in Preparation Example 2 was changed to 36 g, , to give 684 g (99.4%) sulfonic

acid-based polymer-containing particles H in the form of colorless granules.

The polymer of the particles H had a weight-average molecular weight of 700,000, as determined by the method described in the present invention. In addition, the particles H had an average particle size of 132 μm, a content of particles having a size of 63 μm sieve-passed of 1.7% by weight, and a content of particles having a size of 1400 μm sieve-on of 0.6% by weight.

Preparation Example 4

The same procedures as in Preparation Example 1 were carried out except that 10 g of acrylic acid in Preparation Example 1 was changed to 12 g of N-vinylacetamide, , to give 667 g (98.7%) sulfonic acid-based polymer- containing particles I in the form of colorless granules.

The polymer of the particles I had a weight-average molecular weight of 5,000,000, as determined by the method described in the present invention. In addition, the particles I had an average particle size of 188 μm, a content of particles having a size of 63 μm sieve-passed of 0.8% by weight, and a content of particles having a size of 1400 μm sieve-on of 0.8% by weight.

Preparation Example of Base Detergent Particles Two-hundred and ten kilograms of a 50% by weight aqueous sodium dodecylbenzenesulfonate solution, 87.5 kg of a 40% by weight aqueous No. 2 sodium silicate solution, 50 kg of sodium tripolyphosphate, 152 kg of sodium sulfate, 1.67 kg of a 60% by weight aqueous polyethylene glycol (average molecular weight: 13,000) solution, 5 kg of a 40% by weight aqueous acrylic acid-maleic acid copolymer solution, 1 kg of a DM fluorescer, 1 kg of

carboxymethyl cellulose, and water were mixed together, to give a homogeneous slurry having a water content of 50% by weight. Next, this slurry was dried by spray-drying, to give a detergent base material. Further, 90 parts by weight of the resulting detergent base material and 10 parts by weight of zeolite were mixed with a concrete mixer (commercially available from KYC Machine

Industry CO., LTD.), to give base detergent particles A having a water content of 10% by weight. The base detergent particles A had an average particle size of 251 μm and a bulk density as prescribed in JIS K 3362 of 0.45. The components of the resulting detergent particles A are shown in Table 1.

Table 1

Components

Anionic Surfactant LAS-Na 21

Alkaline Substance Na ₂ CO ₃ 10

Sodium Silicate 7

Builder for STPP 10

Capturing '

Water-Hardness

Component

Zeolite 10

Other Components Na ₂ SO ₄ 30.4

Polyethylene Glycol 0.2

Carboxymethyl Cellulose 0.2

Acrylic Acid-Maleic Acid 1

Copolymer

DM Fluorescer 0.2

Water Content 10

Total 100 [% by wtl

Test Example 1 for Redeposition Preventing Property

The test for redeposition preventing property was carried out by

combining the following steps using the sulfonic acid-based polymer-containing particles A obtained in Preparation Example 1 for Sulfonic Acid-Based Polymer, the base detergent particles A obtained in Preparation Example for Base Detergent Particles, and soil particles (Kanuma red clay for gardening, having a size of passing a sieve opening of 200 mesh [purchased from K.K. Kokukoen (10,

Yoshimasa-cho, Izumi-shi, Osaka)], and cotton calico (#2023 calico, sold by Sentaku Kagaku Kyokai).

Step 1: The step of supplying 2.5 g of soil particles to a beaker, thereafter adding 800 mL of hard water (GaCl ₂ : 55.42 mg/L, MgCl ₂ ^» 6H ₂ O: 43.51 mg/L) at 20 ⁰ C thereto, and homogeneously dispersing the mixture while confirming that dirt lumps disappear;

Step 2: adding 100 mL of an aqueous solution of base detergent particles (4.9 g / 100 mL (above-mentioned hard water)) to the beaker; Step 3: introducing 5 pieces of cotton calico of 6 cm x 6 cm (#2023 calico, standard product selected by Nippon Yukagaku Kyokai, sold by Sentaku Kagaku

Kyokai) into the beaker;

Step 4: adding 100 mL of an aqueous solution of sulfonic acid-based polymer- containing particles (0.1 g / 100 mL (above-mentioned hard water)) to the beaker; Step 5: transferring all the cloths and solutions and the like in the beaker into a sample cup attached to Terg-o-tometer, and immediately carrying out washing at 20°C at a rotational speed of 100 ±5 r/min for 10 minutes; Step 6: after washing, taking out clothes from the sample cup, lightly hand- squeezing the cloths so as to have a water content of 200% by weight or less, introducing the cloths into 1,000 mL of used water (CaCl ₂ : 55.42 mg/L,

MgCl ₂ ^» 6H ₂ O: 43.51 mg/L) at 20 ⁰ C ₅ and rinsing with Terg-o-tometer (rotational speed: 100 ±5 r/min) for 3 minutes, the rinsing procedures being carried out for a total of two times; and

Step 7: taking out the calico, air-drying the calico, finishing with iron, determining the reflectance of the obtained cloth at 460 nm (spectrophotometer, commercially available from Nihon Denshoku Kogyo K.K.), and calculating the redeposition preventing ratio [%] in accordance with the following formula:

Redeposition (Reflectance of Cotton Calico After Test)

Preventing Ratio = ^: x 100 , (Reflectance of Cotton Calico Before Test)

Each experiment was carried out by varying the order of the combination of the above steps.

Experiment 1: Steps 1 ^→ 2→3→4→5→6 ^→ 7

Experiment 2: Steps 1 ^→ 4→3 ^→ 2 ^→ 5→6 ^→ 7

Experiment 3: Steps 1 ^→ 3— KZ and 4(concurrentry) ^→ 5 ^→ 6 ^→ 7

The determination results for the redeposition preventing ratios are shown in Table 2. Since the sulfonic acid-based polymer-containing particles are contacted with the cloths at a point later than the base detergent particles, excellent redeposition preventing ratio can be obtained.

Table 2

Experiment 1 Experiment 2 Experiment 3

1 Base Detergent Sulfonic Acid-

Based Polymer

Order of I I Adding both

Action Ϋ si- at one time

2 Sulfonic Acid- Base Detergent

Based Polymer

Redeposition 81 68 73

Preventing

Ratio [%1

< Preparation Example of Sulfonic Acid-Based Polymer-Containing Particles Having Different Particle Sizes > Using JIS standard sieves (2000 μm, 1400 μm, 1000 μm, 710 μm, 500 μm,

355 μm, 250 μm, 180 μm, 125 μm, 90 μm, 63 μm, and 45 μm), each of particle size fractions of the particles A obtained in Preparation Example 1 of Particles > was collected, and thereafter each of the particle size fractions was reconstituted in a ratio as listed in Table 3, to give each of particles A to F having different average particle sizes and different particle size distributions as shown in Table 3.

The particle size distributions of the particles A to F are shown in Figures 1 to 6, respectively. It can be seen from the results shown in each figure that the Particles A had an average particle size of 197 μm (Figure 1); Particles B had an average particle size of 74 μm (Figure 2); Particles C had an average particle size of 467 μm (Figure 3); Particles D had an average particle size of 180 μm

(Figure 4); Particles E had an average particle size of 96 μm (Figure 5); and Particles F had an average particle size of 681 μm (Figure 6).

Examples 1 to 5 and Comparative Examples 1 to 4

Ninety-eight parts by weight of the base detergent particles A and 2 parts by weight each of the sulfonic acid-based polymer-containing particles A to I were homogeneously mixed, to give each of detergent composition A to I. This composition was used for evaluating redeposition preventing property, smoothness and dissolubility. The results obtained are shown in Tables 3 and 4 given below.

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3

Examples 6 to 9 and Comparative Example 5

Further, the base detergent particles A and the sulfonic acid-based polymer-containing particles A are mixed so as to prepare compositions J to N of which ratio of the sulfonic acid-based polymer-containing particles A was sequentially 0.04% by weight, 0.06% by weight, 2% by weight, 4% by weight, and 8% by weight, respectively. The resulting compositions were used for evaluating redeposition preventing property, smoothness and dissolubility. The results are shown in Table 5.

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S

O

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O O

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W

It can be seen from the results shown in Table 5 that the compositions J to M obtained in Examples 6 to 9 are all excellent in redeposition preventing property, and excellent in the evaluation of smoothness and the evaluation of dissolubility, and very low content of insoluble components, while all the panelists showed unpleasant feel caused by excessive smoothness in the composition N obtained in Comparative Examples 5 ^' .

INDUSTRIAL APPLICABILITY

The process for washing and the powder detergent composition of the present invention improve burden of labor upon hand-washing. The composition is applicable for powder detergents especially for hand-washing.