EP1184451A1

EP1184451A1 - Detergent composition

Info

Publication number: EP1184451A1
Application number: EP00937205A
Authority: EP
Inventors: Hiroyuki Kao Corporation SAIJO; Hideichi Kao Corporation NITTA; Shu Kao Corporation YAMAGUCHI; Hiroyuki Kao Corporation YAMASHITA
Original assignee: Kao Corp
Current assignee: Kao Corp
Priority date: 1999-06-14
Filing date: 2000-06-12
Publication date: 2002-03-06
Also published as: EP1184451A4; CN1370225A; CN1193088C; WO2000077157A1

Abstract

The present invention relates to a detergent composition which facilitates hand-washing and excellent in the dissolubility of the granules and the dispersibility comprising 5 to 60% by weight of a phosphate builder and 10 to 60% by weight of a surfactant, wherein the detergent composition has a bulk density of from 600 to 1200 g/L, and a flow time of 10 sec or less, and has a total summation of a product of a mass base frequency Wi of each group of classified granules obtained by classifying detergent granules by using a classifier and a dissolving rate Vi of each group of classified granules specified in the present invention, which satisfies the following formula (1): Σ(Wi•Vi) ≥ 90(%) and wherein a mass base frequency of the classified granules having a size of less than 125 µm is 0.10 or less, wherein the classifier comprises sieves each having a sieve-opening 2000 µm, 1410 µm, 1000 µm, 710 µm, 500 µm, 355 µm, 250 µm, 180 µm, and 125 µm, and a receiver, determined under the measurement conditions; and
a process for preparing the detergent composition.

Description

TECHNICAL FIELD

The present invention relates to a detergent composition and a process for preparing the same.

BACKGROUND ART

A powdery heavy duty detergent has been used for washing using a washing machine, and when there is a great load of stains on fibers, it may be subjected to hand-washing. In the hand-washing, it has been known from experience that the washing efficiency is excellent when the hand-washing is started by directly dispersing the powdery heavy duty detergent to a part of the washing items wetted with water, in order to act a concentrated detergent solution on stains. In this case, since the parts of the washing items themselves or the part of the washing items with other fabric parts are rubbed together with hands, sufficient foaming is necessitated in order to have excellent sliding between the fibers. In addition, in order to facilitate the rubbing-together operation, a powdery heavy duty detergent having a high content in the water-soluble components is preferable. Moreover, in the washing with a composition having a high content in the water-soluble components, since the washing liquid in the washtub is transparent, it is preferable also for visually confirming whether or not the stains are sufficiently washed off as a consequence of washing. From the background described above, a powdery heavy duty detergent having a high content in the water-soluble components, namely a powdery heavy duty detergent containing a large amount of a phosphate builder, is preferable. Further, in order to disperse a desired amount of the powder heavy duty detergent to a part of the washing items, it is necessary that the flowability of the powder is high.
On the other hand, in order to impart great advantages in the improvement in the transportation efficiency and the convenience in the users upon measuring, the powdery heavy duty detergent has been highly densified. However, there has been an increasing concern on the dissolubility by compression of the detergent granules. Especially in the hand-washing, there are concerns that the detergent granules do not readily dissolve during washing, and that the foaming rate which gives sliding between cloths is lowered.
Meanwhile, the washing machine has been developed to have a design for meeting consumers' demands and in considerations of water conservation and energy conservation. For instance, in the Japanese-made washing machines, since the mid 1990's, the washing machines have the tendency of large volume capacity and water conservation, and short-period washing mode or gentle stirring mode for meeting the demands of reduction in clothes damaging has been set. However, in either of the modes, the amount of work (i.e. mechanical power x time) of the washing machine tends to be lowered. As a result, there arise crucial problems that the dissolubility of the detergent granules is drastically lowered, so that the detergency becomes poor, and that the insoluble remnants remain on clothes. Also, in the European-made washing machines and the U.S.-made washing machines, it is considered to be important to lower the washing temperature, from the viewpoint of energy conservation during washing. Therefore, there has been a demand for a detergent having excellent dissolubility.
In order to efficiently carry out not only washing using the washing machines made in various countries but also washing with hands, there has been a demand for a detergent having a fast dissolving speed, the detergent comprising a phosphate builder, and having a high powder flowability, fast foaming, easy washing, and quick disappearance of aggregates of the detergent granules.
However, conventional detergents comprising a phosphate builder have had insufficient dissolubility. In addition, there are tendencies that when the dissolubility of the detergent granules is only improved, the powder flowability is lowered or the dispersibility in water is lowered, and that aggregates of the detergent granules are formed when the detergent powder is acted on wetted clothes during hand-washing at a low temperature, or during washing with a washing machine at a low water temperature, so that not at all of the above requirements are satisfactorily met.

DISCLOSURE OF INVENTION

An object of the present invention is to provide a detergent composition comprising a phosphate builder, which is excellent in the detergency even when the amount of work of the washing machine is low, and excellent in the dissolubility of the granules and the dispersibility so as to easily carry out hand-washing.
The above object and other objects of the present invention will be apparent from the following description.
Specifically, the present invention relates to a detergent composition comprising 5 to 60% by weight of a phosphate builder and 10 to 60% by weight of a surfactant, wherein the detergent composition has a bulk density of from 600 to 1200 g/L, and a flow time of 10 sec or less, and has a total summation of a product of a mass base frequency Wi of each group of classified granules obtained by classifying detergent granules by using a classifier and a dissolving rate Vi of each group of classified granules, which satisfies the following formula (1): Σ(Wi•Vi) ≥ 90(%) and wherein a mass base frequency of the classified granules having a size of less than 125 µm is 0.10 or less, wherein the classifier comprises sieves each having a sieve-opening 2000 µm, 1410 µm, 1000 µm, 710 µm, 500 µm, 355 µm, 250 µm, 180 µm, and 125 µm, and a receiver, and the dissolving rate Vi is determined under the following measurement conditions:
supplying 1.000 g ± 0.010 g of a sample to 1.00 L ± 0.03 L of water at 5°C ± 0.5°C having a water hardness of 4°DH, stirring in a 1 L beaker (inner diameter: 105 mm), with a cylindrical stirring bar (length: 35 mm, diameter: 8 mm), at a rotational speed of 800 rpm for 60 seconds, and thereafter filtering insoluble remnants by a standard sieve (sieve-opening: 74 µm) as defined according to JIS Z 8801, wherein the dissolving rate Vi of the classified granules is calculated by the following formula (2), i being each group of the classified granules: Vi = (1 - Ti/Si) x 100(%) wherein Si is a weight (g) of each group of the classified granules supplied; and Ti is a dry weight (g) of the insoluble remnants of each group of the classified granules remaining on the sieve after filtration; and a process for preparing the detergent composition.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 (1) and (2) each shows a scheme of classification operation in the process of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

[1] Composition

The phosphate builder in the present invention has a content of from 5 to 60% by weight, preferably from 10 to 50% by weight, more preferably from 15 to 45% by weight, of the detergent composition, from the viewpoint of the sliding of the clothes to be washed during hand-washing.
The phosphate builders are preferably one or more kinds selected from tripolyphosphates, orthophosphates, pyrophosphates, and the like. It is favorable that the content of the tripolyphosphate is from 80 to 97% by weight, that the content of the orthophosphate is from 1 to 10% by weight, or that the content of the pyrophosphate is from 2 to 10% by weight, of the entire phosphate builder (the content is calculated as an anhydride). In addition, as the counter ions, the alkali metal ions are preferable, especially, sodium ions and potassium ions are preferable. The sodium ions and potassium ions are contained in an amount of preferably 70% by weight or more, more preferably 85% by weight or more, in the entire counter ions.
The surfactant in the present invention has a content of from 10 to 60% by weight, preferably from 20 to 50% by weight, more preferably from 27 to 45% by weight, of the detergent composition, from the viewpoints of obtaining the detergency and the desired powder properties, and the like. The surfactant comprises an anionic surfactant and/or a nonionic surfactant, and may comprise a cationic surfactant and an amphoteric surfactant as occasion demands.
The anionic surfactants include alkylbenzenesulfonates, alkyl or alkenyl ether sulfates, alkyl or alkenyl sulfates, α-olefinsulfonates, α-sulfofatty acid salts or esters thereof, alkyl or alkenyl ether carboxylates, fatty acid salts, and the like. The anionic surfactant has a content of preferably from 1 to 50% by weight, more preferably from 5 to 30% by weight, of the detergent composition, from the viewpoint of the detergency.
As the counter ions, the alkali metal ions are preferable, from the viewpoint of improvement in the detergency. Especially, potassium ions are preferable, from the viewpoint of the improvement in the dissolution speed. The potassium ions have a content of preferably 5% by weight or more, more preferably 20% by weight or more, particularly preferably 40% by weight or more, of the entire counter ions.
The nonionic surfactants include polyoxyalkylene alkyl ethers, polyoxyalkylene alkylphenyl ethers, polyoxyalkylene fatty acid esters, polyoxyethylene-polyoxypropylene alkyl ethers, polyoxyalkylene alkylamines, glycerol fatty acid esters, higher fatty acid alkanolamides, alkylglycosides, alkylglucosamides, alkylamine oxides, and the like. From the viewpoint of the detergency, polyoxyalkylene alkyl ethers are preferable, which are ethylene oxide adducts, or a mixture adduct of ethylene oxide and propylene oxide, each of which alcohol moiety has 10 to 18 carbon atoms, preferably 12 to 14 carbon atoms, the average moles of each alkylene oxide being 5 to 30, preferably 6 to 15.
In addition, the polyoxyethylene-polyoxypropylene-polyoxyethylene alkyl ether is preferable, from the viewpoints of the detergency and the dissolubility. The compound can be obtained by reacting an ethylene oxide adduct of which alcohol moiety has 10 to 18 carbon atoms, preferably 12 to 14 carbon atoms with propylene oxide and subsequently with ethylene oxide. Further, among the polyoxyethylene alkyl ethers mentioned above, those having a narrow distribution of an alkylene oxide chain are preferable.
The nonionic surfactant has a content of preferably from 1 to 50% by weight, more preferably from 5 to 30% by weight, of the detergent composition, from the viewpoint of the detergency.
The cationic surfactants include alkyl trimethylammonium salts, and the amphoteric surfactants include carbobetaine-type and sulfobetaine-type surfactants. The cationic surfactant and amphoteric surfactant each has a content of preferably from 0.1 to 5% by weight, more preferably from 0.5 to 3% by weight, of the detergent composition.
In the detergent composition of the present invention, there can be formulated water-soluble inorganic salts such as carbonates, hydrogencarbonates, silicates, sulfates, sulfites, and phosphates. As the counter ions, the alkali metal ions such as sodium ions and potassium ions are particularly preferable. Here, the above salts, in particular, the carbonates are contained, calculated as an anhydride, in an amount of preferably 40% by weight or less, more preferably from 5 to 30% by weight, still more preferably from 5 to 25% by weight, of the detergent composition, from the viewpoint of the low-temperature dispersibility after allowing the detergent composition to stand in cold water for a long period of time.
In the detergent composition of the present invention, crystalline silicates can be formulated. The SiO₂/M₂O molar ratio (wherein M is an alkali metal atom) is preferably 0.5 or more, from the viewpoints of the metal ion capturing ability and the anti-hygroscopic property, and the molar ratio is preferably 2.6 or less, particularly preferably from 1.5 to 2.2, from the viewpoint of the alkalizing ability. A preferable crystalline silicate has an average particle size of from about 1 to about 40 µm, from the viewpoints of the fast dissolubility and the powder properties, and its content is preferably from 0.5 to 40% by weight, more preferably from 1 to 25% by weight, of the detergent composition, from the viewpoints of the powder properties and the detergency after storage. Especially, its combined use with sodium carbonate is preferable.
In addition, it is favorable to formulate a cationic exchange-type polymer having carboxyl group and/or sulfonic group in the detergent composition of the present invention, from the viewpoints of the metal ion capturing ability, the dispersibility of the solid particle stains, and the like. Especially, there are formulated salts of acrylic acid-maleic acid copolymers and polyacrylates each having a molecular weight of 1000 to 100000; or salts of polyacetal carboxylic acids such as polyglyoxylic acid having a molecular weight of 800 to 1000000, preferably from 5000 to 200000 described in Japanese Patent Laid-Open No. Sho 54-52196. The cationic exchange-type polymer is contained in an amount of preferably from 0.5 to 12% by weight, more preferably from 1 to 7% by weight, particularly preferably from 2 to 5% by weight, of the detergent composition, from the viewpoint of the detergency.
In addition, in the detergent composition of the present invention, a crystalline aluminosilicate such as A-type, X-type, or P-type zeolite can be formulated. The average primary particle size is preferably from 0.1 to 10 µm. The crystalline aluminosilicate preferably has a content of preferably from 3 to 15% by weight of the detergent composition. Suitable crystalline aluminosilicates are A-type zeolite (for example, trade name: "TOYOBUILDER," manufactured by Tosoh Corporation), which is also preferable from the viewpoints of the metal ion capturing ability and economic advantages. Here, the value of the oil-absorbing ability of A-type zeolite measured by a method according to JIS K 5101 is preferably 40 mL/100 g or more. Further, the suitable crystalline aluminosilicates also include P-type zeolite (for example, trade names: "Doucil A24" and "ZSEO64", both manufactured by Crosfield B.V.; oil-absorbing ability: 60 to 150 mL/100 g); X-type zeolite (for example, trade name: "Wessalith XD" manufactured by Degussa-AG; oil-absorbing ability: 80 to 100 mL/100 g); and hybrid zeolite described in WO 9842622.
In addition, for the purpose of preventing bleeding out of the liquid components such as a nonionic surfactant, there can be formulated amorphous aluminosilicates of which oil-absorbing ability measured by a method according to JIS K 5101 is 80 mL/100 g or more. Also, as the amorphous aluminosilicates, from the viewpoint of maintaining high dissolubility even after being stored for a long period of time (without undergoing property changes), it is desirable that the aluminosilicate has an SiO₂/Al₂O₃ (molar ratio) of 4.0 or less, preferably 3.3 or less. The amorphous aluminosilicates include those having properties described on Japanese Patent Laid-Open No. Hei 5-5100, column 4, line 34 to column 6, line 16 (especially, the oil-absorbing carriers described on column 4, line 43 to 49); and Japanese Patent Laid-Open No. Hei 6-179899, column 12, line 12 to column 13, line 17 and column 17, line 34 to column 19, line 17. Among them, those with 0 to 0.7 mL/g of pores having a pore size, as determined by a mercury porosimeter (manufactured by SHIMADZU CORPORATION, "SHIMADZU Poresizer 9320"), of 0.015 to 0.5 µm, and with 0.30 mL/g or more of pores having a pore size of 0.5 to 2 µm, are preferable. The amorphous aluminosilicate has a content of preferably from 0.1 to 20% by weight of the detergent composition.
It is desirable that the total formulation amount of the crystalline aluminosilicate and the amorphous aluminosilicate, each of which is a water-insoluble inorganic salt in the present invention, and the crystalline silicates which have a delayed dissolution speed in water, is preferably less than 25% by weight, more preferably less than 20% by weight, still more preferably less than 15% by weight, of the detergent composition, from the viewpoint of the easy hand-washing. Also, it is desirable that the total formulation amount, on a weight-ratio basis, is less than 200% by weight, preferably less than 100% by weight, based on the phosphate builder.
The detergent composition of the present invention can be appropriately formulated with organic acid salts such as citrates and ethylenediaminetetraacetate; dispersing agents or dye-transfer inhibitors such as carboxymethyl cellulose, polyethylene glycols, polyvinyl pyrrolidones and polyvinyl alcohols; bleaching agents such as percarbonates; bleaching activators such as compounds listed in Japanese Patent Laid-Open No. Hei 6-316700 and tetraacetylethylenediamine; enzymes such as protease, cellulase, amylase, and lipase; biphenyl-type or stilbene-type fluorescent dyes; defoaming agents; antioxidants; blueing agents; perfumes, and the like.

[2] Bulk Density

The bulk density of the detergent composition determined in accordance with JIS K 3362 is from 600 to 1200 g/L. From the viewpoints of improvement in the transportation efficiency and the convenience of the users, the bulk density is 600 g/L or more, preferably 650 g/L or more, more preferably 700 g/L or more. From the viewpoint of securing the air gaps between the granules and improving the dispersibility owing to the suppression of the increase in a number of contact points between the granules, the bulk density is 1200 g/L or less, preferably 1000 g/L or less, more preferably 850 g/L or less.

[3] Particle Size Distribution

The detergent composition of the present invention is excellent in the dissolubility per one granule of the detergent granules and the aggregation-preventing property of the detergent granules. Here, the aggregation of the detergent granules refers to a phenomenon where after initiation of dissolving a part of a surfactant capable of forming liquid crystals and an inorganic salt forming hydrated crystals of carbonates, sulfates and the like, the remainder part forms highly viscous liquid crystals of the detergent granules or recrystallizes into a hydrate more quickly than being dissolved under the conditions of a low mechanical power, cold water, and the like. Therefore, from the viewpoint of the prevention of the aggregation of the detergent granules, the particle size distribution of the detergent composition of the present invention is such that the mass base frequency of the classified granules having a size of less than 125 µm is 0.10 or less.
From the viewpoints of improvements in the low-temperature dispersibility and the flowability, it is preferable that the content of the fine powder in the detergent composition is low. The mass base frequency of the classified granules having a particle size of less than 125 µm is 0.10 or less, preferably 0.08 or less, more preferably 0.06 or less, particularly preferably 0.04 or less. In addition, the mass base frequency of the classified granules having a particle size of 125 µm or more and less than 180 µm is preferably 0.20 or less, more preferably 0.10 or less, particularly preferably 0.05 or less. Here, regarding the fine powder, it is preferable that each mass base frequency satisfies the relationship such that the mass base frequency is [classified granules having a particle size of less than 125 µm] ≤ [classified granules having a particle size of 125 µm or more and less than 180 µm].
In addition, from the viewpoint of the fast dissolubility per one granule, it is preferable that the content of the coarse granules in the detergent composition is low. Specifically, the mass base frequency of the classified granules having a particle size of 1000 µm or more is preferably 0.03 or less, more preferably 0.01 or less, particularly preferably substantially none. The mass base frequency of the classified granules having a particle size of 710 µm or more and less than 1000 µm is preferably 0.10 or less, more preferably 0.05 or less, particularly preferably 0.03 or less. The mass base frequency of the classified granules having a particle size of 500 µm or more and less than 710 µm is preferably 0.10 or less, more preferably 0.05 or less, still more preferably 0.03 or less. Here, regarding the coarse granules, it is preferable that each mass base frequency satisfies the relationship such that the mass base frequency is [classified granules having a particle size of 1000 µm or more] ≤ [classified granules having a particle size of 710 µm or more and less than 1000 µm] ≤ [classified granules having a particle size of 500 µm or more and less than 710 µm].
The detergent composition of the present invention has an average particle size of preferably from 150 to 500 µm, more preferably from 200 to 400 µm, particularly preferably from 250 to 350 µm. Here, the average particle size (Dp) is a 50% mass base diameter, and can be determined by using the classifier mentioned above. Specifically, after-classification operation, the mass base frequency is accumulated sequentially from finer powders to coarser granules. When a sieve-opening of a first sieve of which cumulative mass base frequency is 50% or more is defined as a µm, and a sieve-opening of one sieve-opening larger than a µm is defined as b µm, in a case where the cumulative mass base frequency from the receiver to the a µm-sieve is defined as c%, and the mass base frequency of granules on the a µm-sieve is defined as d%, the average particle size can be calculated according to the equation (3). Dp = 10A wherein A = 50-(C- dlog b-log a x log b) dlog b - log a

[4] Dissolubility of Classified Granules

In the determination of the dissolubility of each group of the classified granules, first 1.000 g ± 0.010 g of a sample accurately weighed by using, for example, an electronic balance "Model ER-180A" manufactured by Kensei Kogyo K.K. is supplied evenly to 1.00 L ± 0.03 L of water at 5°C ± 0.5°C having a water hardness of 4°DH, so as not to cause aggregation of the granules, and stirred for 60 seconds with a cylindrical stirring bar (length: 35 mm and diameter: 8 mm) at a rotational speed of 800 rpm in a one-liter beaker (inner diameter: 105 mm), and thereafter filtered with a standard sieve defined by JIS Z 8801 (sieve-opening: 74 µm) [the sieve having a sieve area of 35 cm² or more and a weight within 10 g being used, the weight being previously measured]. Subsequently, the insoluble remnants of each group of the classified granules remaining on the sieve are subjected to drying operation together with the sieve for 1 hour in an electric dryer at 105°C, and allowed to cool for 30 minutes in a desiccator (25°C) containing an activated silica gel therein. Thereafter, the weight is determined. By subtracting the weight of the sieve from this determined weight, the dry weight of the insoluble remnants of each group of the classified granules can be calculated.
The concrete determination conditions are as described for the conditions for dissolubility determination described above. Under the conditions, it has been found that the powdery detergent composition having a dissolution rate of 90% or more is extremely easier to dissolve and disappear and has a fast foaming speed even in hand-washing at ambient temperature or a lower temperature.

[5] Dissolubility of Detergent Composition

The dissolubility of the detergent composition of the present invention is expressed by a total summation of a product of a mass base frequency Wi of each group of the classified granules and a dissolution rate Vi of each group of the classified particles [namely Σ(Wi•Vi)]. The dissolubility of the detergent composition of the present invention is 90% or more, preferably 94% or more, more preferably 97% or more. Incidentally, the dissolution rate Vi of the classified particles is calculated by the following equation (2), wherein "i" means each group of the classified particles. Vi = [1 - Ti/Si] x 100 (%) wherein Si is a weight (g) of each group of the classified particles supplied; and Ti is a dry weight (g) of insoluble remnants of each group of the classified particles remaining on the sieve after filtration.
In the detergent composition of the present invention, in hand-washing, a desired amount is easily dispersed to washing items, the dissolution of the granules is fast, and the foaming speed is excellent. Therefore, hand-washing can be extremely efficiently carried out because the detergent composition comprises a phosphate builder as a main builder. Also, since the detergent composition has extremely high dissolubility even under cold water conditions, the probability of generating insoluble remnants even washing under the conditions of super-low mechanical power is extremely low, aside from having such effects that the detergency is increased by eluting the deterging components more quickly in the washtub.

[6] Hand-Washing Dissolubility of Detergent Composition

The detergent composition of the present invention also exhibits remarkably excellent hand-washing dissolubility as compared to those of conventional detergent compositions. The hand-washing dissolubility refers to a measure of the dissolubility when a detergent composition is previously dissolved in a vessel such as a washbowl in a case where stained garments are hand-washed, and expressed by dissolution period of time. Hand-washing is customarily widely employed for washing not only as a matter of course for users whose main washing method is hand-washing but also as pre-washing of stained garments for users whose main washing method is machine washing. Therefore, the hand-washing dissolubility is important as a measure for reflecting a more excellent easy-to-use property.
A concrete method for measurement is as follows. In a washbowl (for example, Model "KW-30" washtub manufactured by YAZAKI, inner volume: 8.2 L) made of polypropylene having a largest opening diameter of 31 cm, a bottom diameter of 24 cm and a height of 13 cm is placed 5.0 L of tap water at 25°C. Next, 15 g of a detergent composition to be tested is added and dispersed on entire water surface uniformly and quickly (within 3 seconds or so as a standard) so as not to aggregate in one site. From this point of time, a skilled panelist initiates stirring with one hand (the dominant hand), with widely stretched five fingers sensing the detergent granules existing at the bottom of the washbowl with finger tips (inner side of the fingers), in such a manner of gently touching the bottom of washbowl with finger tips. Here, stirring is carried out by repeating each clockwise rotations and counterclockwise rotations alternating with a period of 5 rotations. The stirring is carried out so as not to spill the sample solution from the side wall of the washbowl (the stirring is carried out in about 1.0 second per one rotation, and when reversely rotated, a stand-still is held for about 1.0 second as a standard.). In the manner described above, the stirring is continued until the detergent granules are no longer sensed, and the period of time is measured. A panelist repeats a test for a test sample until the deviation of the determined period of time for three runs is within ± 5%, and the average period of time of the three runs is referred to as the period of time for the hand-washing dissolubility of the panelist.
The evaluation is carried out by panelists of 10 or more, and an average value of the period of time for the hand-washing dissolubility for the middle 60% of the panelists, excluding the top 20% and the bottom 20% of the panelists, is referred to as the period of time of the hand-washing dissolubility of the tested detergent composition.
The hand washing dissolubility of the detergent composition of the present invention is preferably 80 seconds or less, more preferably 60 seconds or less, still more preferably 50 seconds or less, particularly preferably 40 seconds or less.

[7] Flowability

It is preferable that its flowability is excellent (more likely to be evenly dispersed) in order to easily disperse the detergent composition of the present invention onto a part of washing items in a desired amount during hand-washing and to alleviate the lowering of the dispersibility when the composition is in contact with water in a case where the composition is locally gathered when the detergent composition is placed in a washing machine. The flowability as flow time (a time period required for cascading 100 mL of powder from a hopper used in a measurement of bulk density according to JIS K 3362) is 10 seconds or shorter, preferably 8 seconds or shorter, more preferably 6.5 seconds or shorter.

[8] Preparation Process

The detergent composition of the present invention can be prepared by subjecting unclassified detergent granules, comprising 5 to 60% by weight of a phosphate builder and 10 to 60% by weight of a surfactant, to classification operation and particle size adjustment operation (the detergent granules being hereinafter also referred to as "base detergent granules"; here, classified granules obtained by subjecting base detergent granules to a plural times of classification operation and operation for particle size adjustment may be also included in the base detergent granules).

(Step 1) Preparation Step of Base Detergent Granules

As one embodiment of the process for preparing base detergent granules, there can be employed a process comprising preparing spray-dried particles comprising a surfactant and a builder, and increasing bulk density of the granules. Such a process includes, for instance, a process comprising stirring and granulating spray-dried particles in a vertical or horizontal mixer, thereby increasing the bulk density. As examples of such processes, there can be employed a process disclosed in Japanese Patent Laid-Open No. Hei 2-49100, comprising stirring and granulating spray-dried particles; a process disclosed in Japanese Patent Laid-Open No. Sho 62-169900, comprising forming dried particles, and thereafter disintegrating and granulating the dried particles; a process disclosed in Japanese Patent Laid-Open No. Sho 62-236897, comprising disintegrating a solid detergent obtained by kneading and mixing detergent raw materials; a process disclosed in Japanese Patent Laid-Open No. Hei 3-33199, comprising neutralizing in a dry state an acid precursor of an anionic surfactant with a granular, solid alkalizing agent in a high-speed mixer, and thereafter adding a liquid binder to form granules, and the like.
In addition, as another embodiment of the process for preparing base detergent granules, there can be employed a process disclosed in Japanese Patent Laid-Open No. Hei 10-176200, comprising granulating a mixture comprising a nonionic surfactant, an acid precursor of an anionic surfactant capable of having a lamellar orientation, and an alkalizing agent, while tumbling with a granulator at a temperature not less than the temperature capable of neutralizing the mixture, and the like.

(Step 2) Classification and Particle Size Adjustment Step

The base detergent granules are subjected to classification and particle size adjustment, whereby the detergent composition of the present invention can be obtained. The classification method therefor includes a method employing a circular or sectoral vibration sieve; an ultrasonic vibration sieve comprising the vibration sieve and an ultrasonic oscillator attached thereto; an air classifier or centrifugal classifier, and the like.
The detergent composition can be obtained by subjecting base detergent granules to at least one step of classification operation; thereafter determining a mass base frequency for each group of sieve-on classified granules and sieve-pass classified granules against an amount of the base detergent granules supplied; and blending each group of classified granules such that the formula (1) as defined above is satisfied, and that a mass base frequency of the classified granules having a size of less than 125 µm is 0.10 or less.
Incidentally, the classification operation may be single-step operation as shown in Figure 1 (1), or two or more steps of operations as shown in Figure 1 (2) as occasion demands. A desired detergent composition can be obtained, for instance, by separating coarse granules in the first-step classification operation, from the viewpoint of the fast dissolubility per one granule; separating fine powder, for instance, classified granules having a size of less than 125 µm, in the second-step classification operation, from the viewpoint of the low-temperature dispersibility; and subjecting part or entire fine powder to granulation operation to be supplied again as the base detergent granules. As the blending method, there can be employed a blending method in a batch process with a V-type mixer, or the like, or in continuous process.
In addition, the detergent composition can be obtained in a high yield by granulating and/or disintegrating the base detergent granules which are excess base detergent granules not subjected to particle size adjustment; and thereafter reusing as the base detergent granules. In other words, those granules, like fine powder having a size of less than 125 µm having excellent dissolubility per one granule but having a concern for decreasing the dispersibility of the detergent composition by an increase in the number of contact points between the granules can be reused as base detergent granules after subjecting to a treatment for increasing particle size such as granulation operation. It is especially important for the detergent composition of the present invention to reduce the mass base frequency of the classified granules having a size of less than 125 µm, and by carrying out the above operations, the process becomes economically advantageous. On the other hand, excess coarse granules which are poor in the dissolubility per one granule can be reused as base detergent granules after subjecting the coarse granules to a treatment for decreasing particle size such as disintegration operation.
Specifically, the classified granules not used in Steps 1 and 2 mentioned above are preferably reused as base detergent granules in reference to the dissolution rate Vi, in a case where, for instance, fine powder having Vi of 90% or more is subjected to granulation operation, or coarse granules having Vi of less than 90% are subjected to disintegration operation, whereby the granules are preferably reused as base detergent granules. The fine powder granulation operation and the coarse granules disintegration operation are exemplified below.

(Fine Powder Granulation Operation)

Excess fine powder may be collected by adding them in the form of fine powder without treatment during the preparation process of Step 1 for the base detergent granules. In addition, as an alternative collecting method, for instance, the excess fine powder may be collected by a process comprising consolidating and granulating in a vertical or horizontal agitation granulator; an extruding granulation process employing an extrusion granulator; a compression-granulation method such as briquetting, and the like. In addition, a binder can be added during granulation.

(Coarse Granules Disintegration Step)

Excess coarse granules can be reused as base detergent granules by, for instance, disintegrating the coarse granules, thereby decreasing their particle size. The disintegrator for coarse granules includes impact crushers such as hammer crusher; impact pulverizers such as atomizers and pin mills; shearing rough pulverizers such as flash mills. These disintegrators may comprise single-step operation, or multi-step operations with the same or different disintegrators. Incidentally, it is preferable to add fine powder as an agent for controlling deposition within devices or as a surface-modifying agent for pulverized surfaces. The fine powder is preferably inorganic powders such as tripolyphosphates, aluminosilicates, silicon dioxide, bentonite, talc and clay amorphous silica derivatives, and especially, crystalline or amorphous aluminosilicates are preferable. In addition, fine powders of inorganic salts such as sodium carbonate and sodium sulfate can be used.
In addition, for the purposes of fixing and smoothening a surface-modifying agent for improving flowability of the disintegrated granules, a surface-modifying step can be provided in the process. For instance, there may be employed the process comprising supplying a composition in a batch process or continuous process into a rotary cylindrical mixer or an agitator, thereby subjecting the composition to tumbling or stirring treatment.
By the combination of the fine powder granulation operation and the coarse granules disintegration operation described above, the detergent composition can be economically advantageously obtained in a high yield from the excess classified detergent granules in Step 2. In addition, after the classification and particle size adjustment steps, there can be formulated enzymes, dyes, perfumes, and the like.

EXAMPLES

Evaluation 1 [Dissolubility of Detergent Composition]

A washing net (model number: AXW22A-5RU0, sieve-opening: 300 x 640 µm) was attached to a side wall portion of a washtub of a washing machine "AISAIGO NA-F70VP1" manufactured by Matsushita Electric Industrial Co., Ltd. Next, 3 kg of clothes (cotton underwear: 50% by weight, dress shirt made of mixed fabric of polyester/cotton: 50% by weight) were placed thereinto, and thereafter 44.0 g of each detergent composition of Examples was added with uniform dispersion. Tap water at 5°C was poured thereinto, and washing was carried out by a setting of "standard course: 3 minutes washing and high water level (66 L)." After termination (without including rinsing step), the amount of the detergent composition remained in the washing net was visually determined by the following evaluation criteria. The water temperature at 5°C was a disadvantageous condition for -thedissolubility of the granules for a 3-minute washing time, so that the evaluation creteria A, B and C indicated that the detergent compositions had excellent dissolubility.

[Evaluation Criteria]

A:: The remnants of the detergent granule being almost zero (estimate number of remained detergent granules: 0 to 5 granules);
B:: No remnant detergent granules (estimate number of remained detergent granules: 6 to 15 granules);
C:: Substantially no remnant detergent granules (estimate number of remained detergent granules: 16 to 30 granules);
D:: The remnants of detergent granules being in small amounts (estimate number of remained detergent granules: 30 to 100 granules);
E:: The remnants of detergent granules being in large amounts (estimate number of remained detergent granules: 101 or more granules, the remnants of paste being also scattered).

Evaluation 2 [Dispersibility of Detergent Composition]

The amount 25.0 g of each detergent composition of Examples was placed in an aggregated state near the outer periphery of one of the dents of a sector, a six-divided section of a pulsator of washing machine "AISAIGO NA-F42Y1" manufactured by Matsushita Electric Industrial Co., Ltd. The amount 1.5 kg of the clothes (the same as in Evaluation 1) was placed in the washtub, without disintegrating the aggregation. Twenty-two liters of tap water at 5°C was poured thereto at a flow rate of 10 L/min in such a way that the water did not directly hit the detergent composition. After the termination of water-pouring, the aqueous mixture was allowed to stand. After 3 minutes from the start of water-pouring, the stir was started with gentle water flow (handwashing-mode). After stirring for 3 minutes, water was discharged, and the states of detergent compositions remained on the clothes and the washtub were visually determined by the following evaluation criteria. The stir strength of this evaluation was very weak as compared to that of the standard mode, so that the evaluation criteria I and II indicated that the detergent compositions had excellent dispersibility. In addition, the term "aggregates" described below refers to a mass of aggregated detergent granules having a diameter of 3 mm or more.

[Evaluation Criteria]

I:: No aggregates;
II:: Substantially no aggregates (1 to 5 masses having a diameter of about 3 mm remaining found);
III:: Aggregates remaining in small amounts (masses having a diameter of about 6 mm being found, and 10 or less masses having a diameter of from 3 to 10 mm being found); and
IV:: Aggregates remaining in large amounts (a large number of masses having a diameter exceeding 6 mm being found).

Evaluation 3 [Hand-Washing Dissolubility]

The hand-washing dissolubility was determined by the measurement method described in the above "[6] Hand-Washing Dissolubility of Detergent Composition." As for the washbowl, the Model KW-30 washtub manufactured by YAZAKI was used, and the hand-washing dissolubility was measured by 10 panelists.

Preparation Example 1 (parts by weight are hereinafter expressed as "parts")

One-hundred parts of a 25% by weight aqueous solution of a sodium linear alkyl(10 to 13 carbon atoms)benzenesulfonate; 3 parts of a sodium alkyl(12 to 16 carbon atoms)sulfate; 2 parts of a polyoxyethylene(average moles of EO: 8) alkyl(12 to 14 carbon atoms) ether (hereinafter referred to as "nonionic surfactant"); 3 parts of a soap (14 to 20 carbon atoms); 30 parts of sodium tripolyphosphate; 2 parts of No. 1 sodium silicate; 10 parts of sodium carbonate; 2 parts of potassium carbonate; 2 parts of sodium sulfate; 0.5 parts of sodium sulfite; 10 parts of a 40% by weight-aqueous solution comprising sodium polyacrylate (average molecular weight: 10000) and an acrylic acid-maleic acid copolymer ("Sokalan CP5") in the weight ratio of 1/3; 1.5 parts of a polyethylene glycol (average molecular weight: 8500); and fluorescent dyes (0.1 parts of "Tinopal CBS-X" and 0.1 parts of "WHITEX SA") were mixed with 49.5 parts of water to prepare a slurry having a solid ingredient of 40% by weight (temperature: 65°C). The resulting slurry was dried by using a countercurrent flow type spray-dryer to give granules having a bulk density of about 300 g/L. The content of volatile matter was 2.1% by weight (amount lost at 105°C for 2 hours). Subsequently, 87 parts of the granules and 0.5 parts of zeolite 4A (average particle size: about 3 µm) were introduced into a High-Speed Mixer (manufactured by Fukae Powtec Corp., volume capacity: 25 L), and mixed. Thereafter, 5 parts of crystalline silicate powders (pulverized product of SKS-6, average particle size: 27 µm) were introduced into the mixer, and the mixture was further pulverized and granulated with stirring, while spraying 4 parts of the above nonionic surfactant thereto. In this process, 3.5 parts of the above powdery zeolite was added for surface-coating immediately before the termination of the process, to give base detergent granules. The entire charged amount was 5 kg.

Preparation Example 2

Fifty-six parts of a 25% by weight aqueous solution of a potassium linear alkyl(10 to 13 carbon atoms)benzenesulfonate; 8 parts of a sodium salt of methyl ester of á-sulfofatty acid (14 to 16 carbon atoms); 1 part of the same nonionic surfactant as in Preparation Example 1; 7 parts of the same soap as in Preparation Example 1; 20 parts of sodium tripolyphosphate; 1 part of No. 1 sodium silicate; 5 parts of sodium carbonate; 16 parts of potassium carbonate; 1.1 parts of sodium sulfate; 1.5 parts of sodium sulfite; 5 parts of a 40% by weight aqueous solution of sodium polyacrylate (average molecular weight: 10000); 2 parts of the same polyethylene glycol as in Preparation Example 1; and fluorescent dyes (0.2 parts of "Tinopal CBS-X" and 0.1 parts of "WHITEX SA") were mixed with 45.9 parts of water to prepare a slurry having a solid ingredient of 48% by weight (temperature: 65°C). The resulting slurry was dried by using a countercurrent flow type spray-dryer to give granules having a bulk density of about 320 g/L. The content of volatile matter was 5% by weight (amount lost at 105°C for 2 hours). Subsequently, 50 kg/Hr of the above granules, 4 kg/Hr of sodium carbonate (heavy ash), 1 kg/Hr of the same crystalline silicate powders as in Preparation Example 1, and 3 kg/Hr of the same nonionic surfactant as in Preparation Example 1 were continuously supplied to a continuous kneader (manufactured by Kurimoto Tekkosho K.K.). The resulting mixture was pelletized by using a twin-screw extruder ("PELLETER DOUBLE," manufactured by Fuji Paudal Co., Ltd.) arranged at the discharge outlet of the kneader, to give cylindrical pellets having a diameter of about 3 mm. Five parts of powdery zeolite (average particle size: about 3 µm) as an aid agent for pulverizing, based on 100 parts of the pellets, was added, and pulverizing and granulation process was carried out by a Fitz Mill (manufactured by Hosokawa Micron Corporation) equipped with a screen having a 1.5 mm-sieve opening with aeration of cool air at 14°C, to give base detergent granules.

Preparation Example 3

Base detergent granules (1) were prepared in an amount of 35 kg for each unit from 32% by weight of a linear alkylbenzenesulfonic acid (LAS; molecular weight: 322); 20% by weight of sodium tripolyphosphate (STPP; average particle size: 11.2 µm), 12% by weight of zeolite; 29.9% by weight of sodium carbonate; 1.6% by weight of sodium sulfate; 0.5% by weight of an acrylic acid-maleic acid copolymer ("Sokalan CP5"); fluorescent dyes (0.2% by weight of "Tinopal CBS-X" and 0.1% by weight of "WHITEX SA"), 0.5% by weight of an enzyme (manufactured by NOVO Nordisk, "Savinase 18T Type W"), 0.2% by weight of a perfume, and 3.0% by weight of water, using a high-speed mixer Lödige Mixer "FKM-130D" (manufactured by Matsubo Co., Ltd.). This mixer was equipped with agitator blades and a shearing device, the shearing device corresponding to a chopper for disintegration and dispersion.
The operations were carried out as follows.

The solid ingredients comprising 7.0 parts of sodium tripolyphosphate, 12.61 parts of sodium carbonate ("LIGHT ASH," manufactured by Central Glass Co., Ltd.; average particle size: 56.1 µm), and 0.11 parts of a fluorescent dye were blended for one minute under the conditions of a rotational speed of agitator blades of 130 rpm (peripheral speed: 3.4 m/s) and a rotational speed of a shearing device of 2850 rpm (peripheral speed: 27 m/s) by the Lödige Mixer.

Water (0.20 parts) was added to the contents in the mixer as a reaction initiating agent, and the blending was carried out for 1.5 minutes under the same conditions.

While the mixer was operated under the same conditions as above, 10.92 parts of a sodium linear alkyl(10 to 13 carbon atoms)benzenesulfonate (LAS) and 0.23 parts of 98% sulfuric acid, which were mixed in advance, were added to the mixer in four minutes. During the addition, the ingredients were cooled by allowing water at 25°C to flow through the mixer jacket. At this stage, the temperature rose to 75°C in the highest. Incidentally, throughout this stage, the reaction mixture remained in a granular form. Incidentally, the LAS mentioned above was prepared by SO₃ gas sulfonation method and contained 0.16 parts of sulfuric acid. The amount of sodium carbonate was about six times the amount required for neutralizing the LAS and sulfuric acid. After the addition of the LAS, the mixer was continuously operated under the same conditions for one minute to complete the neutralization reaction and the granulation operation.

At a point where the neutralization reaction and the granulation operation were completed, 0.45 parts by weight of a 40% by weight aqueous solution of acrylic acid-maleic acid copolymer (effective ingredient: 0.18 parts) was added to the mixer, while the mixer was operated under the same conditions as above, and the ingredients were mixed for 1.5 minutes. Subsequently, the resulting mixture was subjected to a surface-coating by adding 4.2 parts of powdery zeolite (average particle size: 3 µm) to the mixer as a surface modifier, and operating the mixer for additional two minutes. Thereafter, 0.175 parts by weight of an enzyme and 0.07 parts by weight of a perfume were added, to give the base detergent granules (1).

[Classification Operations for Base Detergent Granules]

Classification operations were carried out with each group of the base detergent granules of Preparation Examples 1 to 3 using the classifier described above. Specifically, 100 g/batch of a sample was first supplied on a 2000-µm sieve arranged at top of the classifier. Thereafter, the classifier was capped, and attached to a rotating and tapping shaker machine (manufactured by HEIKO SEISAKUSHO, tapping: 156 times/min, rolling: 290 times/min), and vibrated for 10 minutes. Thereafter, the samples remaining on each of the sieves and a receiving tray were individually collected to obtain necessary amounts of samples of each group of the classified granules having sizes of 1410 µm or more to less than 2000 µm, 1000 µm or more to less than 1410 µm, 710 µm or more to less than 1000 µm, 500 µm or more to less than 710 µm, 355 µm or more to less than 500 µm, 250 µm or more to less than 355 µm, 180 µm or more to less than 250 µm, 125 µm or more to less than 180 µm, and ones on the tray to 125 µm (less than 125 µm).

[Classification Operations for Enzyme Granules]

The same classification operations as those of the base detergent granules were carried out for Enzyme Granules A (manufactured by NOVO Nordisk, "Savinase 18T Type W"), to give each group of the classified enzyme granules.

[Determination of Dissolution Rate Vi of Each Group of Classified Granules]

The dissolution rate of each group of the classified granules was determined in accordance with the determination method described above. The results are shown in Table 1.

Vi	Prep. Ex.1	Prep. Ex.2	Prep. Ex.3	Enzyme A
V [1410-2000µm]	42.1	53.1	46.3	-
V [1000-1410µm]	56.1	64	59.1	59.4
V [710-1000µm]	68	70	67.1	74.4
V [500- 710µm]	85	86	73.2	81.3
V [355- 500µm]	96.9	99	92.1	95.0
V [250- 355µm]	100	100	97.2	99.7
V [180- 250µm]	100	100	100	-
V [125- 180µm]	100	100	100	-
V [Less than 125µm]	100	100	100	-

Example 1

High-bulk density detergent compositions of Cases 1 to 9 were obtained using the classified granules of the base detergent granules obtained in Preparation Examples 1 to 3 and Enzyme Granules A by carrying out particle size adjustment in accordance with the following process. The average particle size, the bulk density, the flowability and Σ(Wi·Vi) of each of the resulting detergent compositions are shown in Table 2.

Operation 1 for Adjusting Particle Size Distribution

Each group of the classified granules was weighed so that each sample weighed 200 g in accordance with a mass base frequency distribution of the particle size shown in Table 2, and each sample was mixed for 2 minutes by a rocking mixer (manufactured by Aichi Electronics Co., Ltd.) to prepare various detergent compositions of which particle size was adjusted.

The detergent compositions of Cases 1 to 9 shown in Table 2 were evaluated in accordance with the Evaluations 1 to 3. As a result, it has been found that the detergent compositions of

Cases

1, 2, 4, 5 and 8 satisfying the formula (1) of Σ(Wi•Vi) ≥ 90(%) and having a mass base frequency of the classified granules having sizes of less than 125 µm of 0.10 or less were excellent in the dissolubility, the dispersibility and the hand-washing dissolubility.

	Case1	Case2	Case3	Case4	Case5	Case6	Case7	Case8	Case9
	Prep. Ex.1	Prep. Ex.1	Prep. Ex.1	Prep.Ex.1	Enzyme Granules A	Prep. Ex.2	Prep. Ex.2	Prep. Ex.2	Prep. Ex.3	Prep. Ex.3
W [1410-2000µm]	0.00	0.02	0.00	0.00	0.00	0.02	0.03	0.00	0.00	0.01
W [1000-1410µm]	0.00	0.04	0.00	0.00	0.00	0.03	0.09	0.00	0.00	0.10
W [710-1000µm]	0.00	0.06	0.00	0.01	0.01	0.06	0.23	0.01	0.01	0.22
W [500-710µm]	0.01	0.06	0.01	0.05	0.02	0.07	0.24	0.02	0.06	0.20
W [355-500µm]	0.09	0.18	0.05	0.20	0.00	0.17	0.19	0.09	0.27	0.13
W [250- 355µm]	0.45	0.38	0.12	0.33	0.00	0.39	0.12	0.15	0.29	0.10
W [180- 250µm]	0.40	0.16	0.30	0.31	0.00	0.16	0.05	0.24	0.19	0.09
W [125- 180µm]	0.03	0.08	0.35	0.04	0.00	0.08	0.03	0.26	0.10	0.08
W [Less than 125 µm]	0.02	0.02	0.17	0.03	0.00	0.02	0.02	0.23	0.08	0.07
Average Partiole Size [µm]	255	330	160		268	220	554	175	309	530
Bulk Density [g/L]	720	730	650		720	760	780	770	740	748
Flowability [sec]	6.5	6.8	> 10		6.7	6.4	6.2	> 10	6.9	6.7
Σ (Wi·Vi) [%]	99.6	93.7	99.7		97.7	95.0	84.9	99.3	95.1	81.5
Evaluation 1	A	C	A		A-B	B	D	A	A-B	D
Evaluation 2	I	II	IV		I	I	I	IV	II	II
Evaluation 3 [sec]	41	67	38		52	62	100	43	66	111

Example 2

Each of the detergent compositions of Cases 10 to 14 was obtained using the classified granules of the base detergent granules (1) obtained in Preparation Example 3 by carrying out particle size adjustment in accordance with the following process. The average particle size, the bulk density, the flowability and Σ(Wi•Vi) of each of the resulting detergent compositions are shown in Table 3.

Operation 2 for Adjusting Particle Size Distribution

One-hundred parts of the base detergent granules (1) obtained in Preparation Example 3 were classified by a gyratory screen (manufactured by Tokuju Kosakusho) having a screen having a 500 µm-sieve opening. The sieve-on granules were removed to give 55.1 parts of the detergent composition of Case 10.

Operation 3 for Adjusting Particle Size Distribution

The amount 55.1 parts of the detergent composition of Case 10 was introduced as base detergent granules into a gyratory screen having a screen having a 125 µm-sieve opening to remove fine particles having a size of less than 125 µm, thereby giving 51.1 parts of the detergent composition of Case 11.

Operation 4 for Adjusting Particle Size Distribution

In the same manner as in Operation 2 for adjusting particle size distribution, 100 parts of the base detergent granules (1) obtained in Preparation Example 3 were introduced into a gyratory screen having a screen having a 500 µm-sieve opening, and classified into sieve-on granules A and sieve-pass granules A, wherein the weights thereof were 44.5 parts and 55.3 parts, respectively. The amount 44.5 parts of the sieve-on granules A and 2 parts of powdery zeolite (average particle size: 3 µm) were fed as an aid agent for pulverizing into a Fitz Mill (manufactured by Hosokawa Micron Corporation) with cooling air, to give first-step pulverized granules. Thereafter, the first-step pulverized granules were fed into the second step of the Fitz Mill to give second-step pulverized granules. The opening of the screen of the Fitz Mill for the firststep had a diameter of 2 mm and that for the second-step had a diameter of 1 mm. The average particle size of the second-step pulverized granules was 376 µm. Of the 46.7 parts of the second-step pulverized granules, granules having a size of 500 µm or more occupied 23.2 parts. The second-step pulverized granules were introduced into the above gyratory screen having a screen having a 500 µm-sieve opening, and classified into sieve-on granules B and sieve-pass granules B. The amount 25.0 parts of sieve-pass granules B and 55.5 parts of the sieve-pass granules A were blended to give 80.5 parts of the detergent composition of Case 12.

Operation 5 for Adjusting Particle Size Distribution

The amount 80.5 parts of the detergent composition of Case 12 was introduced into the above gyratory screen having a screen having a 125 µm-sieve opening to remove fine particles having a size of less than 125 µm, thereby giving 76.2 parts of the detergent composition of Case 13.

Operation 6 for Adjusting Particle Size Distribution

The amount 80.5 parts of the detergent composition of Example 12 was introduced into a gyratory screen having a screen having a 180 µm-sieve opening, and classified into sieve-on granules C and sieve-pass granules C. The weights of the sieve-on granules C and the sieve-pass granules C were 65.1 parts and 15.4 parts, respectively.
The sieve-pass granules C were granulated according to the following operations. The amount 15.4 parts of the sieve-pass granules C were introduced into the above High-Speed Mixer, and 0.77 parts of the above nonionic surfactant was sprayed thereto over a period of 1.3 minutes. Thereafter, the mixture was granulated with stirring for 10 minutes. Subsequently, the resulting granules were subjected to a surface-coating treatment for 1 minute by adding 0.92 parts of zeolite (average particle size: about 3 µm), to give base detergent granules (2) (average particle size: 662 µm). The base detergent granules were classified into sieve-on granules A' and sieve-pass granules A' using a gyratory screen having a 500 µm-sieve opening. The sieve-on granules A' were subjected to two-step pulverizing, using a Fitz Mill to classify the resulting pulverized granules into sieve-on granules B' and sieve-pass granules B' using a gyratory screen having a 500 µm-sieve opening. Thereafter, the sieve-pass granules B', the sieve-pass granules A' and the sieve-pass granules C were blended to give 80.0 parts of the detergent composition of Case 14.

Each of the detergent compositions of Cases 10 to 14 shown in Table 3 was evaluated in accordance with the Evaluations 1 to 3. As a result, it was found that all of the detergent compositions of Cases 10 to 14 were excellent in the dissolubility, the dispersibility and the hand-washing dissolubility. Here, it has been found that the detergent compositions of Cases 11, 13, and 14 having a low mass base frequency of the classified granules having sizes of less than 125 µm were particularly excellent in the dispersibility.

Base Detergent Granules Used	Case10	Case11	Case12	Case13	Case14
	Prep. Ex. 3	Prep. Ex. 3	Prep. Ex. 3	Prep. Ex. 3	Prep.Ex. 3
W [1410-2000µm]	0.00	0.00	0.00	0.00	0.00
W [1000-1410µm]	0.00	0.00	0.00	0.00	0.00
W [710-1000µm]	0.00	0.00	0.00	0.00	0.00
W [500- 710µm]	0.00	0.00	0.00	0.00	0.00
W [355- 500µm]	0.15	0.14	0.30	0.29	0.25
W [250- 355µm]	0.30	0.32	0.30	0.32	0.40
W [180- 250µm]	0.30	0.38	0.22	0.22	0.34
W [125- 180µm]	0.20	0.16	0.14	0.17	0.01
W [Less than 125µm]	0.05	0.00	0.04	0.00	0.00
Average Particle
Size [µm]	210	230	270	265	270
Bulk Density [g/L]	690	704	680	690	670
Flowability [sec]	6.8	6.6	6.7	6.3	6.8
Σ (Wi•Vi) [%]	98.0	98.0	96.8	96.8	96.9
Evaluation 1	A	A	A	A	A
Evaluation
2	II	I	I - II	I	I
Evaluation 3 [sec]	48	50	53	51	52

Test Example 1

The results of the dissolubility of the granules and the hand-washing dissolubility for 8 kinds of representative detergent compositions which have been sold or were sold before in Asia, Europe and the U.S.A. are shown in Table 4.

It is clear from the results shown in Table 4 that these marketed detergents are low in level of the dissolubility of the granules, and also poor in the hand-washing dissolubility. In addition, of the marketed detergents A to H, the detergent A which was the most excellent in the dissolubility of the granules and the hand-washing dissolubility, was notably poor in the flowability.

	Σ (Wi · Vi) [%]	Time Period of Hand-Washing Dissolubility [s]
Asia
Marketed Detergent A	84.6	111
Marketed Detergent B	77.6	135
Marketed Detergent C	67.7	152
Marketed Detergent D	70.4	130
Europe
Marketed Detergent E	73.1	121
Marketed Detergent F	76.4	141
U.S.A.
Marketed Detergent G	58.6	164
Marketed Detergent H	58.4	156

INDUSTRIAL APPLICABILITY

The detergent composition of the present invention rapidly dissolves after supplying to water, even with cold water, is excellent in dissolubility when subjected to hand-washing, and the dispersibility owing to aggregation of the granules, and is excellent in detergency and dissolubility even under washing conditions of low-mechanical power as employed in recent washing machines.

EQUIVALENT

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.

Claims

A detergent composition comprising 5 to 60% by weight of a phosphate builder and 10 to 60% by weight of a surfactant, wherein the detergent composition has a bulk density of from 600 to 1200 g/L, and a flow time of 10 sec or less, and has a total summation of a product of a mass base frequency Wi of each group of classified granules obtained by classifying detergent granules by using a classifier and a dissolving rate Vi of each group of classified granules, which satisfies the following formula (1): Σ(Wi•Vi) ≥ 90(%) and wherein a mass base frequency of the classified granules having a size of less than 125 µm is 0.10 or less, wherein the classifier comprises sieves each having a sieve-opening 2000 µm, 1410 µm, 1000 µm, 710 µm, 500 µm, 355 µm, 250 µm, 180 µm, and 125 µm, and a receiver, and the dissolving rate Vi is determined under the following measurement conditions: supplying 1.000 g ± 0.010 g of a sample to 1.00 L ± 0.03 L of water at 5°C ± 0.5°C having a water hardness of 4°DH, stirring in a 1 L beaker (inner diameter: 105 mm), with a cylindrical stirring bar (length: 35 mm, diameter: 8 mm), at a rotational speed of 800 rpm for 60 seconds, and thereafter filtering insoluble remnants by a standard sieve (sieve-opening: 74 µm) as defined according to JIS Z 8801, wherein the dissolving rate Vi of the classified granules is calculated by the following formula (2), i being each group of the classified granules: Vi = (1 - Ti/Si) x 100(%) wherein Si is a weight (g) of each group of the classified granules supplied; and Ti is a dry weight (g) of the insoluble remnants of each group of the classified granules remaining on the sieve after filtration.
A process for preparing the detergent composition of claim 1, comprising subjecting unclassified detergent granules comprising 5 to 60% by weight of a phosphate builder and 10 to 60% by weight of a surfactant to classification operation; and adjusting a particle size of each group of the resulting classified granules, such that the formula (1) as defined in claim 1 is satisfied, and that a mass base frequency of the classified granules having a size of less than 125 µm is 0.10 or less.