DESCRIPTION METHOD FOR PRODUCING DETERGENT PARTICLES

FIELD OF THE INVENTION 5 [0001]

The present invention relates to a method for producing detergent particles.

BACKGROUND OF THE INVENTION 10 [0002]

Currently, commercially available detergents can be roughly classified into high-bulk density detergents (more than 600 g/L), medium-bulk density detergents (from 400 to 600 g/L), low-bulk density detergents (250 g/L or more and less than 400 g/L), liquid detergents, and the like. For example, while the lf> high-bulk density detergents have been chiefly used in Japan, the medium- to low-bulk density detergents have been also in great demands in Asia and Oceania, Europe, and the like. [0003]

In the low-bulk density detergents, the mainstream of the method for 20 producing the detergent is a method for producing the detergent including the steps of formulating an anionic surfactant and other builder in the form of a slurry, and spray-drying the slurry. Qn the other hand, in the medium- to high- bulk density detergents, the mainstream of the method for producing the detergent is a method for producing the detergent including the steps of 25 formulating an anionic surfactant and other builder in the form of a slurry, spray-

drying the slurry, and thereafter subjecting spray-dried particles to a treatment of increasing a bulk density. [0004]

In the production of the medium- to high-bulk density detergents, when the spray-dried .particles are subjected to an increase in a bulk density with a high-speed mixer equipped with a high-speed shea/ mechanism, or the like, generally an average particle size is undesirably increased along with the increase in a bulk density. Therefore, disadvantages of lowering in dissolubility and an yield of a manufactured article have been known to take place, and improvements in both dissolubility and an yield of a manufactured article are earnestly desired. In view of such disadvantages, for example in JP-A-Hei-1- 247498, a method including the step of treating spray-dried particles continuously according to a method of applying a very high shear force such as a Froude number of from 50 to 1,200 thereto using a specialized rotary mixer in which mixing blades are arranged in a spiral form, thereby increasing a bulk density has been reported. However, the method is greatly restricted in an apparatus and the operating conditions therefor, and the increase in a bulk density is 200 g/L at its maximum. [0005] To date, when the spray-dried particles containing an anionic surfactant are continuously subjected to a mixing treatment with a high-speed mixer, adhesion and cohesion ofi the particles themselves, which are causative of the viscosity of the anionic surfactant are generated. Therefore, a breaking load gradually increases, at least far exceeding 9,800 mN, and the particles become coarse concurrently with an increase in a bulk density.

SUMMARY OF THE INVENTION [0006]

The present invention relates to a method for producing detergent particles including the steps of spray-drying a slurry containing an anionic surfactant and increasing bulk density of the resulting particles with a high-speed mixer, wherein a mixing treatment is carried out at a breaking load at 25°C of 9,800 mN or less and at a degree of particle growth, i.e. an average particle size after a treatment of increasing a bulk density / an average particle size before a treatment of increasing a bulk density, of equal to or smaller than 1.1, wherein an extent of an increase in the bulk density before and after the treatment of increasing a bulk density is from 20 to 800 g/L.

BRIEF DESCRIPTION OF THE DRAWINGS [0007]

Figure 1 is an illustration showing that particles are placed in an adapter container for the determination of a breaking load of the particles to produce a molded article.

Figure 2 is an illustration showing that a further load is applied to a molded article obtained by compression molding.

Figure 3 is an illustration showing that a detergent molded article is disintegrated by a load.

DETAILED DESCRIPTION OF THE INVENTION [0008]

The present invention relates to a method of producing the medium- to high-bulk density detergents while inhibiting particle growth by a method of treating the detergent particles when the detergent particles are subjected to a treatment of increasing a bulk density with a high-speed mixer equipped with a high-speed shear mechanism, or the like, under conditions that surface adhesion of the detergent particles during the treatment takes a value that does not exceed a certain value (expressed in terms of a breaking load of 9,800 mN or less).

[0009]

According to the present invention, a medium- to high-bulk density detergent can be produced without causing lowering in dissolubility and an yield of a manufactured article accompanying an increase in the bulk density. In addition, since the surface adhesion does not take a value equal to or greater than a certain value, the detergent particles are less likely to be adhered to the inside of a high-speed mixer, whereby the detergent particles having stable powdery physical properties can be produced even during continuous production.

[0010]

According to the present invention, an effect in which a medium- to high- bulk density detergent can be produced while inhibiting particle growth is exhibited. These and other advantages of the present invention will be apparent from the following description.

[0011]

The term "breaking load" in the present invention refers to an index showing surface adhesion of the detergent particles. The higher the value of the breaking load, the higher the surface adhesion, so that the granulation proceeds

among the detergent particles, thereby causing the formation of coarse detergent particles.

[0012]

In the present invention, a desired detergent particle can be produced by properly combining conditions as mentioned below, thereby controlling a breaking load to an appropriate level. [0013]

Compositionally, spray-dried particles containing large amounts of an anionic surfactant, an organic polymer, and water have a high breaking load. In the conditions for the mixing treatment, the higher the peripheral speed of the main shaft, the higher the increasing rate of the breaking load. [0014]

The term "detergent particle" in the present invention refers to a particle obtained by subjecting the spray-dried particles containing an anionic surfactant, other builder, and the like to a mixing treatment, and the term "detergent particles" means an aggregate thereof. In addition, a detergent composition as mentioned below means a composition containing the detergent particles and further containing separately added detergent components other than the detergent particles (for example, a fluorescer, an enzyme, a perfume, a defoaming agent, a bleaching agent, a bleaching activator, or the like).

[0015] < Spray-Dried Particles >

The spray-dried particles in the present invention are particles obtained by spray-drying a water-soluble slurry containing an anionic surfactant, other

builder, and the like. Each of the components used in the present invention will be explained hereinbelow.

[0016] 1. Anionic Surfactant

The anionic surfactant which is generally used is usable, and includes, for example, linear alkylbenzenesulfonates, α-olefinsulfonates, alkyl sulfates, olefinsulfonates, fatty ester sulfonates, alkyl ether sulfates, and the like. These anionic surfactants can be used as a single component, or in combination of two or more components. In addition, a counterion is preferably an alkali metal, and more preferably sodium. Among the anionic surfactants, sodium linear alkylbenzenesulfonates (LAS-Na) are preferable, and a LAS-Na having an alkyl group with an average number of carbon atoms of from 10 to 15 is more preferable from the viewpoint of economic advantage, storage stability, and foamability.

[0017]

The above-mentioned anionic surfactant is contained in the slurry in an amount of preferably 10% by weight or more, more preferably 15% by weight or more, and even more preferably 20% by weight or more, of the resulting spray- dried particles, from the viewpoint of detergency. In addition, the above- mentioned anionic surfactant is contained in the slurry in an amount of preferably 40% by weight or less, more preferably 30% by weight or less, and even more preferably 25% by weight or less of the resulting spray-dried particles, from the viewpoint of extending a controlling range of bulk density while inhibiting the formation of coarse particles.

[0018]

An essential component of the spray-dried particles in the present invention is only an anionic surfactant, and other component which is ordinarily used in a detergent composition can be optionally contained in the spray-dried particles from the viewpoint of detergency, particle size distribution, and particle strength. For example, other component includes a water-soluble solid alkali inorganic substance, a chelating agent, a water-soluble inorganic salt, a water- soluble polymer, a water-insoluble excipient, a nonionic surfactant, a cationic surfactant, other auxiliary component, and the like. Among them, it is preferable that the spray-dried particles contain a water-soluble solid alkali inorganic substance, a chelating agent, a water-soluble inorganic salt, and a water-soluble polymer are formulated.

Further, the spray-dried particles of the present invention can be optionally formulated with a substance given below.

[0019] 2. Water-Soluble Solid Alkali Inorganic Substance

The term "water-soluble solid alkali inorganic substance" refers to an alkali inorganic substance which is solid at an ambient temperature (20 ⁰ C), and it is preferable that a substance can be dissolved in an amount of 1 g or more, preferably 5 g or more, and more preferably 10 g or more, in 100 g of water at 20 ⁰ C. The water-soluble solid alkali inorganic substance is not particularly limited, and an alkali metal salt, a silicate, or the like having a hydroxide group, a carbonate group, or a hydrogencarbonate group can be used. The water-soluble solid alkali inorganic substance includes, for example, sodium hydroxide,

sodium carbonate, sodium hydrogencarbonate, potassium carbonate, sodium silicate, and the like. Among them, sodium carbonate is preferable as an alkalizing agent showing a suitable pH buffering range in a washing liquid. The water-soluble solid alkali inorganic substance is contained in the slurry in an amount of preferably 5% by weight or more, more preferably 10% by weight or more, and even more preferably 20% by weight or more, of the resulting spray- dried particles, from the viewpoint of detergency. The water-soluble solid alkali inorganic substance is contained in the slurry in an amount of preferably 40% by weight or less, more preferably 38% by weight or less, and even more preferably 35% by weight or less, of the resulting spray-dried particles, from the viewpoint of not impairing the degree of compositional freedom.

[0020]

3. Chelating Agent The chelating agent can be formulated in the spray-dried particles in order to suppress the inhibition of deterging action by metal ions, and examples thereof are water-soluble chelating agents and water-insoluble chelating agents. [0021] It is desired that the amount of the chelating agent is adjusted so that the chelating agent is contained in an amount of preferably from 3 to 60% by weight, more preferably from 5 to 40% by weight, and even more preferably from 10 to 40% by weight, of the spray-dried particles, from the viewpoint of metal ion capturing ability. The chelating agents are water-soluble chelating agents and water-insoluble chelating agents, and plural chelating agents can be

simultaneously formulated in the spray-dried particles, in which case it is desired that the total content is arbitrarily adjusted in the amount as mentioned above. [0022]

The water-soluble chelating agent is not particularly limited as long as the water-soluble chelating agent is a substance having a metal ion capturing ability.

The water-soluble chelating agent which can be dissolved in an amount of 1 g or more in 100 g of water at 20 ⁰ C is preferable, and for example, tripolyphosphate, orthophosphate, pyrophosphate or the like can be used. Among them, tripolyphosphate is preferable, and the tripolyphosphate is contained in an amount of preferably 60% by weight or more, more preferably 70% by weight or more, and even more preferably 80% by weight or more, of the entire water- soluble chelating agents. Also, as the counterion, an alkali metal salt is preferable, and a sodium salt and/or a potassium salt is more preferable. [0023] The water-insoluble chelating agent may be added to the spray-dried particles for the purposes of improving the metal ion capturing ability and enhancing the strength of the spray-dried particles. A water-insoluble chelating agent which can be dissolved in an amount of less than 1 g in 100 g of water at 20 ⁰ C is preferable. For example, a water-insoluble chelating agent having an average particle size of from 0.1 to 20 μm and preferably from 0.5 to 10 μm is preferable, from the viewpoint of dispersibility in water. The preferred water- insoluble chelating agents include crystalline aluminosilicates, including, for example, A-type zeolite, P-type zeolite, X-type zeolite, and the like. The A-type zeolite is preferable from the viewpoint of the metal ion capturing ability and economic advantages.

[0024]

As to the content of the crystalline aluminosilicate, it is preferable that the crystalline aluminosilicate is formulated so that a total amount of the chelating agents is in the above range from the viewpoint of the metal ion capturing ability. On the other hand, the crystalline aluminosilicate is contained in an amount of preferably 30% by weight or less and more preferably 20% by weight or less, of the spray-dried particles, from the viewpoint of suppressing remnants during washing.

[0025]

4. Water-Soluble Inorganic Salt

It is preferable that the water-soluble inorganic salt is formulated in the spray-dried particles in order to enhance the ionic strength of the washing liquid and improve the effects of deterging sebum stains and the like. The water- soluble inorganic salt is not particularly limited as long as the water-soluble inorganic salt is a substance that has an excellent dissolubility and does not give worsening influence to detergency. For example, a water-soluble inorganic salt which can be dissolved in an amount of 1 g or more in 100 g of water at 20 ⁰ C is preferable. The water-soluble inorganic salt includes, for example, an alkali metal salt or ammonium salt, having a sulfate group or a sulfite group, and the like. Among them, it is preferable that sodium sulfate, sodium chloride, sodium sulfite, or potassium sulfate having a high degree of ionic dissociation is used as an excipient. Also, its combined use with magnesium sulfate is also effective from the viewpoint of increasing the dissolution rate. [0026]

The water-soluble inorganic salt is contained in an amount of preferably from 5 to 80% by weight, more preferably from 10 to 70% by weight, and even more preferably from 20 to 60% by weight, of the spray-dried particles, from the viewpoint of the ionic strength.

[0027] 5. Water-Soluble Polymer

The water-soluble polymer may be added to the spray-dried particles for the purpose of enhancing the particle strength by film formation on the spray- dried particles. The water-soluble polymer includes organic polymers and inorganic polymers. For example, the organic polymer includes carboxylate polymers, carboxymethyl cellulose, soluble starches, saccharides, polyethylene glycol, and the like, and the inorganic polymer includes amorphous silicates and the like. Among them, the carboxylate polymers are preferable, and among the carboxylate polymers, a salt of an acrylic acid-maleic acid copolymer and a salt of a polyacrylic acid (counterion: Na, K, NH ₄ and the like) are more preferable. Those carboxylate polymers having an average molecular weight of from 1,000 to 8,000 are preferable, and those having an average molecular weight of 2,000 or more and 10 or more carboxyl groups are more preferable. The organic polymer is contained in an amount of preferably from 0.1 to 10% by weight, and more preferably from 0.5 to 5% by weight, of the spray-dried particles. In addition, the inorganic polymer is contained in an amount of preferably from 0.1 to 20% by weight, and more preferably from 0.5 to 10% by weight, of the spray- dried particles.

[0028]

6. Water-Insoluble Excipient

The water-insoluble excipient is not particularly limited, as long as the water-insoluble excipient is a substance that has an excellent dispersibility in water and does not give worsening influence to detergency. The water-insoluble excipient includes, for example, crystalline or amorphous aluminosilicates, silicon dioxide, hydrated silicic acid compound, clay compounds such as barite and bentonite, and the like. The water-insoluble excipient has an average primary particle size of preferably from 0.1 to 20 μm, and more preferably from 0.5 to 10 μm from the viewpoint of the dispersibility in water.

The water-insoluble excipient is contained in an amount of preferably 50% by weight or less and more preferably 30% by weight or less, of the spray- dried particles, from the viewpoint of economic advantages and dispersibility.

[0029]

7. Water

Water is contained in an amount of preferably 0% by weight or more, more preferably 3% by weight or more, and even more preferably 5% by weight or more, of the spray-dried particles, from the viewpoint of the speed of increasing bulk density. On the other hand, the water is contained in an amount of preferably 20% by weight or less and more preferably 15% by weight or less, of the spray-dried particles, from the viewpoint of the facilitation in control of a breaking load.

[0030]

8. Other Auxiliary Components

A fluoresces a pigment, a dye or the like may be formulated in the spray- dried particles.

[0031] The spray-dried particles used in the present invention can be obtained by spray-drying a slurry prepared by adding each of the above-mentioned components and mixing. Here, the water content of the slurry and spray-drying conditions are not particularly limited. For example, the spray-dried particles are obtained according to a method described in Tokkyocho Koho: Shuchi Kanyo Gijutsu Shu (Clothes Powder Detergent: Japanese Patent Office),

10(1998)-25(7159).

[0032] < Preferred Composition > From the viewpoint that the speed of increasing a bulk density is dramatically lowered when a crystalline sodium aluminosilicate and sodium silicate are used together in the spray-dried particles, sodium silicate, in a case where both the crystalline sodium aluminosilicate and sodium silicate are used together, is contained in an amount of preferably 20% by weight or less, more preferably 15% by weight or less, and even more preferably 10% by weight or less, of the spray-dried particles. The crystalline sodium aluminosilicate and sodium silicate are contained in a total amount of preferably 50% by weight or less, more preferably 45% by weight or less, even more preferably 40% by weight or less, and even more preferably 30% by weight or less, of the spray- dried particles.

[0033] < Detergent Particles >

The detergent particles in the present invention are obtained by controlling a breaking load to a range of 9,800 mN when the above-mentioned spray-dried particles are subjected to a treatment of increasing a bulk density. The detergent particles having a bulk density from 300 g/L to 1,500 g/L are obtained by, for example, a method including the step of subjecting the spray- dried particles to a treatment of increasing a bulk density at a breaking load of 9,800 mN or less; or a method including the steps of adding a given amount of an agent for inhibiting surface adhesion to the spray-dried particles before a breaking load exceeds 9,800 mN, continuing a treatment of increasing a bulk density, and repeating the above steps.

[0034] A method for producing the detergent particles used in the present invention will be explained hereinbelow. [0035]

The detergent particles when terminating the treatment of increasing bulk density or adding a certain amount of the agent for inhibiting surface adhesion thereto has a breaking load of preferably 9,800 mN or less, more preferably

7,840 mN or less, and even more preferably 5,880 mN or less, from the viewpoint of inhibiting the growth of a particle size. On the other hand, a breaking load is preferably 490 mN or more, more preferably 980 mN or more, and even more preferably 1,960 mN or more, from the viewpoint of the speed of

increasing a bulk density. A method for determining a breaking load will be described in Examples set forth below.

[0036] < Agent for Inhibiting Surface Adhesion >

In the detergent particles of the present invention, a final bulk density can be adjusted by adding the agent for inhibiting surface adhesion during the treatment of increasing a bulk density and continuing the treatment for the purpose of inhibiting the growth of a particle size due to an increase in the surface adhesion of the detergent particles.

[0037]

As the agent for inhibiting surface adhesion, any of known ones that are ordinarily used can be used, and sodium tripolyphosphate, a crystalline or amorphous aluminosilicate, a crystalline sodium silicate, diatomaceous earth, silica, or the like is suitably used. Among them, one or more members selected from the group consisting of sodium tripolyphosphate and crystalline aluminosilicates, each of which have chelating ability are preferable. By surface-modifying the detergent particles with the substance having chelating ability, the chelating ability acts from the beginning of washing, and whereby detergency is improved. The crystalline aluminosilicate is more preferable from the viewpoint of free-flowing property, and sodium tripolyphosphate is more preferable from the viewpoint of rinsability. [0038]

Here, it is desired that the particles used as the agent for inhibiting surface adhesion have an average particle size corresponding to a size of 1/10 or less,

and preferably 1/20 or less, of an average particle size of the detergent particles, from the viewpoint of coating ability, and an average particle size corresponding to a size of 1/3000 or more, and preferably 1/600 or more, of an average particle size of the detergent particles, from the viewpoint of handling during the production.

[0039]

In addition, the agent for inhibiting surface adhesion is contained in an amount of preferably 1% by weight or more, more preferably 2% by weight or more, and even more preferably 3% by weight or more, of the detergent particles, from the viewpoint of the speed of increasing a bulk density. On the other hand, the agent for inhibiting surface adhesion is contained in an amount of preferably 20% by weight or less, more preferably 15% by weight or less, and even more preferably 10% by weight or less, of the detergent particles, from the viewpoint of inhibiting the surface adhesion. [0040]

In the present invention, although the addition of a liquid binder is not a mandatory condition, a liquid binder may be added to gather together fine powders which are generated, thereby increasing free-flowability upon the treatment of increasing a bulk density. The liquid binder includes, for example, any liquid components in the detergent particles such as water, a liquid nonionic surfactant, an aqueous solution of a water-soluble polymer (polyethylene glycol, an acrylic acid-maleic acid copolymer, or the like), a fatty acid, and the like. The liquid binder may be used in combination of two or more components, in which case examples thereof include addition methods, including (1) adding a mixture of two or more components of the liquid binders mixed in advance; (2) adding

each of the liquid binders simultaneously; and (3) adding each of the liquid binders alternately. In any method, it is preferable that water is used together from the viewpoint of lowering the production cost. The liquid binder is contained in an amount of preferably 10 parts by weight or less, more preferably 5 parts by weight or less, and even more preferably 3 parts by weight or less, based on 100 parts by weight of the spray-dried particles, from the viewpoint of inhibiting aggregation of the detergent composition. In addition, the liquid binder is contained in an amount of preferably 0.1 parts by weight or more, and more preferably 0.3 parts by weight or more, based on 100 parts by weight of the spray-dried particles, from the viewpoint of the effect of reducing the fine powders.

[0041]

A method of adding a liquid binder includes continuous addition or divided addition, or batch addition, and batch addition at the end of the treatment of increasing a bulk density is preferable from the viewpoint of satisfying both suppressing particle growth and incorporating the generated fine powders into the detergent particles. [0042] A means of carrying out the treatment of increasing a bulk density is not particularly limited as long as an apparatus is capable of mixing the spray-dried particles, the agent of inhibiting surface adhesion, and a free-flowing aid. However, a vertical granulator having a disintegrating mechanism, a horizontal granulator having a disintegrating mechanism, a rotary mixer having a baffle plate, or the like is preferable from the viewpoint of applying a high shear force to the spray-dried particles.

[0043]

When the above-mentioned vertical granulator is used, the main shaft has a peripheral speed of preferably from 1 to 7 m/s, and more preferably from 2 to 5 m/s, from the viewpoint of the speed of increasing a bulk density and facilitation in inhibiting a breaking load. In addition, blades which are the disintegrating mechanism have a rotational speed of preferably from 500 to 4,000 rpm, and more preferably from 1,000 to 2,000 rpm, from the same viewpoint as mentioned above. When the above-mentioned horizontal granulator is used, the main shaft has a peripheral speed of is preferably from 0.5 to 3 m/s. In addition, blades which are the disintegrating mechanism have a rotational speed of preferably from 500 to 4,000 rpm, and more preferably from 1,000 to 2,000 rpm. [0044]

The detergent particles in the present invention have a degree of particle growth after the treatment of increasing a bulk density, i.e. an average particle size after the treatment of increasing a bulk density / an average particle size before the treatment of increasing a bulk density, of 1.1 or less, preferably from 0.6 to 1.1, more preferably from 0.7 to 1.1, and even more preferably from 0.8 to 1.1, from the viewpoint of dissolubility and an yield of a manufactured article. In addition, the extent of an increase in the bulk density of the detergent particles in the present invention before and after the treatment of increasing a bulk density is from 20 to 800 g/L, preferably from 30 to 600 g/L, and more preferably from 40 to 500 g/L. [0045]

Here, the detergent particles in the present invention can be subjected to surface-modification with a free-flowing aid after the treatment of increasing a bulk density, for the purposes of a further improvement in free-flowability and an improvement in storage stability. [0046]

As the average particle size of the free-flowing aid, those having the same average particle size as the agent for inhibiting surface adhesion can be used.

[0047]

In addition, the free-flowing aid is contained in an amount of preferably from 2 to 20 parts by weight, and more preferably from 5 to 15 parts by weight, based on 100 parts by weight of the detergent particles, from the viewpoint of free-flowability.

[0048]

In addition, in the production step of the detergent particles in the present invention, a substance used in the detergent composition can be optionally properly added.

[0049] < Detergent Composition > The detergent composition of the present invention contains detergent components that are separately added other than the detergent particles (for example, a fluorescer, an enzyme, a perfume, a defoaming agent, a bleaching agent, a bleaching activator, or the like). The detergent composition of the present invention having the above-mentioned constitution can be produced by properly mixing each of the above-mentioned components by a known method.

In addition, the detergent particles of the present invention are contained in an amount of preferably from 50 to 100% by weight, and more preferably from 70 to 100% by weight, of the detergent composition.

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.

[0050]

Example 1 < Preparation of Spray-Dried Particles >

The spray-dried particles were prepared by the following procedures. The amount 292.32 kg of water at a temperature of 60 ⁰ C and 40.71 kg of a 48% by weight aqueous sodium hydroxide solution were sequentially added to a 1 m ³ -mixing vessel having agitation blades with a jacket set at 60 ⁰ C. After agitating the mixture for 5 minutes, 146.53 kg of a linear alkylbenzenesulfonic acid (LAS: an alkyl group having an average number of carbon atoms from 10 to 15) was added thereto. After agitating the mixture for 10 minutes, 238.46 kg of sodium sulfate, 63.60 kg of sodium carbonate, 57.24 kg of sodium tripolyphosphate, 127.20 kg of a 40% by weight aqueous No. 2 sodium silicate solution, and 2.13 kg of a 60% by weight aqueous polyethylene glycol (PEG) solution were added thereto. Thereafter, the mixture was agitated for 120 minutes, to provide a slurry. The water content of this slurry was 42% by weight. [0051]

This slurry was sprayed at a spraying pressure of 35 kg/cm ² with a pressure spray nozzle arranged near the top of a spray-drying tower, to provide the spray-dried particles. A high-temperature gas fed to the spray-drying tower was supplied at a temperature of 205 ⁰ C to the bottom of the tower and exhausted at a temperature of 95°C from the top of the tower. The compositions of the resulting spray-dried particles are shown in Table 1.

O

Table 1 _ _^

Compositions of Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Comp. Comp.

Spray-Dried Particles Ex. 1 Ex. 2

Water Content of Slurry [wt %] 42 42 46 46 53 42 46

LAS-Na [wt %] 24 24 18 18 36 24 23

STPP [wt %] 9 9 0 0 8 9 0

Zeolite [wt %] 0 0 20 20 0 0 18

Sodium Carbonate [wt %] 10 10 20 20 9 10 6

No. 2 Sodium Silicate [wt %] 8 8 6 6 8 8 18 NJ to

Sodium Sulfate [wt %] 38 38 32 32 25 36 30

Copolymer [wt %] 2 2 0 0 2.0 2 0

PEG [wt %] 0.2 0.2 1 1 0.2 0.2 1.5

Oligomer D [wt %] 0 0 1 1 0 0 2.5

Water [wt %] 8.8 8.8 2 2 11.8 10.8 1

Total [wt %] .100 100 100 100 100 100 100

[0053] < Preparation of Detergent Particles >

One-hundred kilograms of the spray-dried particles obtained by the above-mentioned procedures and 1.18 kg of a transport zeolite (a zeolite A-type: an average particle size of 3 μm) were supplied into High-Speed Mixer

(manufactured by Fukae Powtec Kogyo Corp.; Model FS-400; full volume: 455 L; equipped with a jacket) in which warm water at 40 ⁰ C was allowed to pass through the jacket at 40 L/min, and the mixture was agitated for 13 minutes with a peripheral speed of the main shaft of 4 m/s and a rotational speed of disintegrating blades (choppers) of 1,800 rpm. Thereafter, 4.72 kg of a zeolite

A-type (average particle size: 3 μm) was added thereto as a free-flowing aid, and a surface modification was carried out for 30 seconds with a peripheral speed of a main shaft of 4 m/s and a rotational speed of the disintegrating blades (choppers) of 1,800 rpm, to provide detergent particles. The preparation conditions of the detergent particles are shown in Table 2.

[0055] < Determination Results for Physical Properties of Detergent Particles >

The determination results for physical properties and a dissolution ratio of detergent particles before and after the treatment of increasing bulk density (indicated as "treatment of increasing bulk density") are shown in Table 3. The time for treatment of increasing the bulk density was 15 minutes, and the treatment was terminated when a breaking load attained to 4,900 mN. The detergent particles had a bulk density of 660 g/L, a degree of particle growth of 0.70, a granulation yield of 99%, and a dissolution ratio of 99%, showing a high granulation yield and a high dissolution ratio even after an increase in the bulk density.

[0057]

The physical properties of the spray-dried particles and the detergent particles can be determined by the methods described below.

[0058]

< Breaking Load >

An adapter having a diameter of 30 mm is attached to a rheometer (manufactured by Fudo Kogyo Kabushiki Kaisha) as shown in Figures 1 to 3. Thereafter, the detergent particles in a weight [g] calculated by dividing a bulk density [g/L] by 20 are set in a cylindrical container made of a metal, and

9,800 mN of a load is applied at an ambient temperature for 3 minutes to compress the detergent particles. Subsequently, the detergent particles are taken out from the container, and a board is then raised at a rising rate of 2 cm/min, from which a force is applied to the particles molded by compression, to determine the force at which a molded article is broken.

[0059]

< Average Particle Size >

The detergent particles are vibrated for 5 minutes with a Ro-Tap sieve shaker (rotational speed: 265 rpm, tapping speed: 145 tpm) using standard sieves according to JIS Z 8801. After vibrating the detergent particles for 5 minutes, the average particle size can be determined from a particle size distribution on a weight basis according to the size openings of each of the sieves.

[0060]

< Bulk Density >

The bulk density can be determined by a method for determining a bulk density according to JIS K 3362.

[0061]

< Degree of Particle Growth >

The degree of particle growth is expressed by the formula: (average particle size after the treatment of increasing bulk density) / (average particle size before the treatment of increasing bulk density) .

[0062]

< Granulation Yield >

The granulation yield is a ratio of the detergent particles having a size of a 1,400 μm-sieve (standard sieve)-opening-pass according to JIS Z 8801. [0063]

The dissolution ratio can be determined by a method described below.

[0064]

< Dissolution Ratio > A 1-L beaker (a cylindrical form having an inner diameter of 105 mm and a height of 150 mm, for example, a 1-L glass beaker manufactured by Iwaki Glass Co., Ltd.) is charged with 1 L of hard water adjusted to 5°C and having a water hardness equivalent to 71.2 mg CaCO ₃ /L (molar ratio: Ca/Mg: 7/3). While keeping the water temperature constant at 5 ⁰ C with a water bath, water is stirred with a stirring bar [length: 35 mm and diameter: 8 mm, for example, Model

"TEFLON SA" (MARUGATA-HOSOGATA), manufactured by ADVANTEC] at a rotational speed (800 r/min), such that a depth of swirling to the water depth is about 1/3. The detergent particles (1,400 μm-sieve-opening pass) which are accurately sample-reduced and weighed so as to be 1.0000 g ± 0.0010 g are supplied and dispersed in water while stirring, and the dispersion is continued stirring. 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 μm according to JIS Z 8801 (corresponding to ASTM No. 200) of a known weight. Thereafter, water- containing detergent particles remaining on the sieve are collected in an open vessel of a known weight together with the sieve. Here, the operation time from the beginning of filtration to collection of the sieve is 10 sec ± 2 sec. The insoluble remnants of the collected detergent particles are dried for one hour with an electric dryer heated to 105 ⁰ C. Thereafter, the dried insoluble remnants are kept in a desiccator with a silica gel (25°C) for 30 minutes and cooled. After cooling the insoluble remnants, a total weight of the dried insoluble remnants of the detergent particles, the sieve, and the vessel is determined, and a dry weight of the detergent particles remaining on the sieves is determined. Thereafter, the dissolution ratio (%) of the detergent particles is calculated by the following formula. Here, the weight is determined by using a precision balance.

Dissolution Ratio (%) = {1 - (T/S)} x 100 wherein S is a weight (g) of the detergent particles supplied; and T is a dry weight (g) of the detergent particles remaining on the sieve.

[0065]

Examples 2 to 5 and Comparative Examples 1 and 2

< Preparation of Spray-Dried Particles >

The same procedures as in Example 1 were carried out using a composition of 1,000 kg of a slurry, to provide spray-dried particles each having a composition as shown in Table 1.

[0066]

< Preparation of Detergent Particles >

The spray-dried particles were prepared as same as Example 1 with conditions shown in Table 2, to provide detergent particles.

[0067]

< Determination Results for Physical Properties of Detergent Particles >

The determination results for the physical properties obtained in the same manner as Example 1 are shown in Table 3. Examples 2 to 5 gave the results in which a high granulation yield and high dissolution ratio are maintained even after the treatment of increasing bulk density in the same manner as in Example 1 by ending the treatment of increasing bulk density at a breaking load of 9,800 mN or less, or adding an agent for inhibiting surface adhesion to the detergent particles so that a breaking load would not exceed 9,800 mN, and continuing the treatment of increasing bulk density. [0068]

On the other hand, in Comparative Example 1 where the treatment of the increasing bulk density was carried out to the spray-dried particles having a higher water content than that of the composition of Example 1 until a breaking

load exceeds 9,800 mN, the detergent particles had a bulk density of 807 g/L, a degree of particle growth of 6.90, a granulation yield of 30%, and a dissolution ratio of 88%, so that the granulation yield and the solubility are both lowered,. In addition, although the treatment of increasing bulk density was carried out for 3 minutes in Comparative Example 2, an increase in the bulk density is not found at all.

INDUSTRIAL APPLICABILITY [0069] According to the present invention, a medium-to-high-bulk density detergent can be produced without causing lowering of the dissolubility or lowering of the yield of the manufactured article, that accompanies the treatment of increasing a bulk density.

EQUIVALENTS

[0070]

The present invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims