2. Description of the Related Art Conventionally, bleaching agents consisting chiefly of sodium hypochlorite, which has a high bleaching power even at low temperatures, have been widely used against colored contaminants and the like adhering to hard surfaces such as metals, glass, porcelain, plastics and the like used in various types of dishes, cooking utensils, household items and the like, and chlorine type bleach detergents prepared by mixing surfactants with sodium hypochlorite have also been used. However, in case where the objects being washed are made of metals, chlorine type bleaching agents or bleach detergents tend to cause rusting. Furthermore, in the case of dishes made of glass, porcelain, plastics or the like, drawbacks such as peeling or fading of ornamentation and decrease in luster have been encountered. Furthermore, there is a danger of accidental misuse in combination with acidic substances, and environmental contamination such as water pollution and the like has become a concern in recent years.

Recently, therefore, oxygen type bleaching agents such as hydrogen peroxide, and sodium percarbonate, sodium perborate and the like which release hydrogen peroxide in an aqueous solution, or oxygen type bleach detergents in which surfactants are added

to such oxygen type bleaching agents, have begun to be widely used.

However, oxygen type bleaching agents or bleach detergents have a weak bleaching power compared to chlorine type bleaching agents or bleach detergents, and also suffer from the drawback of poor stability of the hydrogen peroxide in aqueous solution.

Japanese Patent Application Laid-Open No. 4-372694 discloses a liquid bleaching agent composition in which the bleaching power and storage stability of hydrogen peroxide are improved by including hydrogen peroxide, a surfactant, poly-a-hydroxyacrylic acid or a salt or polylactone thereof, and a polyacrylic acid or maleic acid type polymer. Japanese Patent Application Laid-Open No. 4-331299 discloses a bleaching agent composition which contains a peroxide compound, a surfactant, a bleach activating agent consisting of tetraacetylethylenediamine and/or glucose pentaacetate, and poly-a-hydroxyacrylic acid or a salt or polylactone thereof.

Furthermore, Japanese Patent Application Laid-Open No. 7- 278597 discloses a powder bleach detergent composition containing a peroxide compound, a high molecular weight polymer and specified enzymes as a composition that improves the bleaching power against food spill contamination such as curry and the like.

Meanwhile, when dishes, cooking utensils and the like are bleached using an oxygen type bleaching agent or bleach detergent, the pH of the aqueous solution is set at a value that is weakly alkaline to alkaline; as a result, hard components in the water such as calcium, magnesium and the like aggregate to form scale, which adheres to the surfaces of the dishes or the like.

Especially in cases where bleaching is performed using warm water at a temperature of approximately 60°C in order to enhance the working characteristics, such scale formation tends to be promoted. Furthermore, the adhesion of such scale gives an impression that the dishes are not clean, and lowers the luster of the dishes or the like.

In the abovementioned Japanese Patent Application Laid-Open No. 4-372694, Japanese Patent Application Laid-Open No. 4-331299 and Japanese Patent Application Laid-Open No. 7-278597, it is disclosed that the bleaching power and hydrogen peroxide stability are improved by combining specified components.

However, there is no mention of the prevention of scale formation, there has been a demand for bleach detergents that have scale formation inhibiting power.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a bleach detergent composition which is superior in terms of the storage stability of the composition and stability of the available oxygen in aqueous solution, and which also suppresses the generation of scale during the bleaching of dishes, cooking utensils and the like, has properties that prevent corrosion of the object of washing, and has a superior bleaching power and detergency even in hard water.

As a result of diligent research conducted for the purpose of achieving the abovementioned object, the present inventors perfected the present invention. Specifically, the first aspect of the present invention is a powder bleach detergent composition characterized by comprising (A) 25 to 85 mass% peroxide compound, (B) 0.3 to 2.5 mass% poly-a-hydroxyacrylic acid and/or salt thereof, (C) 0.5 to 5 mass% high molecular weight compound, being a homopolymer and/or copolymer with monomer structural units selected from acrylic acid, methacrylic acid, and maleic acid, (D) 0.4 to 2 mass% anionic surfactant and/or nonionic surfactant, and (E) 10 to 30 mass% carbonate.

Furthermore, the second aspect of the present invention is the abovementioned powder bleach detergent composition in which the peroxide compound of component (A) is sodium percarbonate, and the third aspect of the present invention is the abovementioned powder bleach detergent composition in which the poly-a-hydroxyacrylic acid and/or salt thereof of component (B) is sodium poly-a-hydroxyacrylate. Furthermore, the fourth aspect

of the present invention is the abovementioned powder bleach detergent composition in which the high molecular weight polymer of component (C) is a polymer of acrylic acid and/or a copolymer of acrylic acid and maleic acid. Moreover, the fifth aspect of the present invention is the abovementioned powder bleach detergent composition in which the surfactant of component (D) is a nonionic surfactant.

The sixth aspect of the present invention is the abovementioned powder bleach detergent composition which is used for the bleaching and cleaning of dishes, cooking utensils or the like.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The powder bleach detergent composition of the present invention is a powder-form composition which contains the abovementioned component (A), component (B), component (C), component (D) and component (E) as active ingredients.

Examples of compounds which can be used as the peroxide compound of component (A) used in the present invention include percarbonates such as sodium percarbonate, potassium percarbonate and the like, perborates such as sodium perborate and the like, perphthalates such as sodium perphthalate and the like, perphosphates, and compounds formed by adding hydrogen peroxide to sodium sulfate, sodium silicate or the like. These compounds may be used singly, or in combinations consisting of two or more compounds. Among these compounds, percarbonates are preferable from the standpoints of safety and protection of the environment, and sodium percarbonate is especially preferable for use. In regard to the available oxygen content of such peroxide compounds, a compound with a content of 11% is ordinarily used in the case of sodium percarbonate, and a compound with a content of 15% is ordinarily used in the case of sodium perborate.

The amount of this peroxide compound of component (A) that is added to the powder bleach detergent composition of the present invention (hereafter referred to as the"composition") is selected from the range of 25 to 85 mass% of the composition. In

cases where this amount is less than 25 mass%, the bleaching power is not sufficiently manifested; on the other hand, even if this amount exceeds 85 mass%, no improvement in the bleaching power is observed, and such a large amount is economically disadvantageous, and restricts the amounts of other components that are added. From the standpoints of economy, balance with other performance values and the like, it is preferable that the amount of the abovementioned peroxide compound that is added be in the range of 40 to 80 mass% based on the total weight of the composition, and an amount in the range of 60 to 80 mass% is even more preferable from the standpoint of the bleaching power.

Component (B) used in the present invention is poly-a- hydroxyacrylic acid and/or a salt thereof. This compound may be used in the form of an acid, or all or part of the compound may be used in the form of a salt. Examples of salts that can be used include sodium salts, potassium salts, amine salts, ammonium salts and the like. This component is water-soluble and shows a chelating action, thus contributing to the stabilization of the available oxygen in aqueous solution. In combination with the other components, this component also contributes to the improvement of the bleaching power, detergency and scale formation inhibiting power. In the case of the poly-a- hydroxyacrylic acid or salt thereof used in the present invention, the average molecular weight is selected from a range of 1,000 to 1,000, 000. From the standpoint of the stability of the available oxygen in aqueous solution, a range of 2,000 to 800,000 is desirable, and from the standpoint of the bleaching power, a range of 2,000 to 200,000 is even more desirable. In particular, from the standpoints of solubility in water and economy, it is desirable that all or part of the salt in the poly-a- hydroxyacrylic acid be a sodium salt.

The amount of this component (B) that is added to the composition is selected from the range of 0.3 to 2.5 mass% of the composition. In cases where this amount is less that 0.3 mass%, the component lacks an effect in improving the stability of the

available oxygen in an aqueous solution of the composition. On the other hand, even if the amount added exceeds 2.5 mass%, the effect in improving the stability of the available oxygen in an aqueous solution of the composition becomes saturated, and such a large amount is economically disadvantageous. From the standpoints of economy and stability of the available oxygen in an aqueous solution of the composition, it is desirable that the amount of the abovementioned poly-a-hydroxyacrylic acid and/or salt thereof that is added to the composition be in the range of 0.5 to 2 mass% based on the total weight of the composition.

Component (C) used in the present invention is a high molecular weight polymer consisting of a homopolymer and/or copolymer which contains monomers selected from acrylic acid, methacrylic acid and maleic acid as structural units. One type of such polymer may be used, or two or more types may be used in combination. These high molecular weight polymers may be in the form of an acid, or all or part of the polymers may be in the form of a salt. These high molecular weight polymers are added for the purpose of endowing the composition with a scale formation inhibiting power. In combination with other components, these polymers also contribute to the improvement of the bleaching power, detergency and properties that prevent re- contamination.

Homopolymers that can be used as component (C) include polyacrylic acid and salts thereof, polymethacrylic acid and salts thereof, and polymaleic acid and salts thereof. Examples of salts that can be used include sodium salts, potassium salts, amine salts, ammonium salts and the like. In particular, it is preferable that all or part of the salt be a sodium salt.

Furthermore, copolymers that can be used include copolymers of acrylic and methacrylic acid and salts thereof, copolymers of acrylic acid and maleic acid and salts thereof, and copolymers of methacrylic acid and maleic acid and salts thereof. Examples of salts that can be used include sodium salts, potassium salts,

amine salts, ammonium salts and the like. In particular, it is preferable that all or part of the salt be a sodium salt.

Furthermore, from the standpoint of scale formation inhibiting power, it is desirable that the average molecular weight of the homopolymers and salts thereof used in component (C) be in the range of 3,000 to 20,000, and, from the standpoints of bleaching power, detergency and properties that prevent re- contamination, a range of 4,000 to 8,000 is even more preferable.

Meanwhile, from the standpoint of scale formation inhibiting power, it is desirable that the average molecular weight of the copolymers and salts thereof used in component (C) be in the range of 30,000 to 100,000 ; furthermore, from the standpoints of bleaching power, detergency and properties that prevent re- contamination, a range of 50,000 to 80,000 is even more desirable.

In particular, from the standpoints of scale formation inhibiting power and properties that prevent re-contamination, homopolymers of acrylic acid and/or copolymers of acrylic acid and maleic acid are especially preferable. Furthermore, from the standpoint of economy, it is preferable that all or part of the salt in these polyacrylic acid polymers and/or copolymers of acrylic acid and maleic acid be a sodium salt.

The amount of this component (C) that is added to the composition is selected from a range of 0.5 to 5 mass%. In cases where this amount is less than 0.5 mass%, the composition is insufficiently effective in terms of scale formation inhibiting power. On the other hand, even if the amount exceeds 5 mass%, the improvement in the scale formation inhibiting power becomes saturated, and such a large amount is economically disadvantageous. From the standpoints of scale formation inhibiting power and economy, it is desirable that the amount of the abovementioned high molecular weight polymer that is added to the composition be in the range of 1 to 5 mass% based on the total weight of the composition, and from the standpoint of economy, an amount in the range of 1 to 3 mass% is even more desirable.

Component (D) used in the present invention is added to the composition for the purpose of improving the detergency of the composition. This component consists of a single anionic surfactant and/or nonionic surfactant, or of two or more such surfactants used in combination.

Here, example of anionic surfactants that can be used include alkyl or alkenyl ether sulfates, alkyl-or alkenylsulfates, olefinsulfonates, alkanesulfonates, alkyl or alkenyl ether carbonates, and a-sulfo-fatty acid salts or esters thereof. In particular, from the standpoint of detergency, alkylbenzenesulfonates, alkanesulfonates, alkylsulfuric acid ester salts, alkyl ether sulfuric acid ester salts and a- olefinsulfonates are especially desirable for use.

Examples of nonionic surfactants that can be used include polyoxyalkylene alkyl ethers, polyoxyalkylene alkenyl ethers, polyoxyalkylene alkylphenyl ethers, polyoxyalkylene alkenylphenyl ethers, higher fatty acid alkanolamides or alkylene oxide adducts thereof, fatty acid glycerol monoesters, sucrose fatty acid esters, polyoxyethylene higher fatty acid alkanolamides, amine oxides and the like. In particular, from the standpoints of detergency and permeability, polyoxyalkylene alkyl ethers are especially desirable for use.

Polyoxyalkylene alkyl ethers are expressed by the formula R- (Ao) n-R'. R indicates an alkyl group, alkenyl group, alkylphenyl group or alkenylphenyl group, and from the standpoint of detergency, a group with 6 to 24 carbon atoms is desirable. Ao indicates an alkylene oxide. Examples of such alkylene oxides include ethylene oxide, propylene oxide, butylene oxide and the like. A single alkylene oxide may be used, or two or more such alkylene oxides may be used in combination. n indicates the number of moles of alkylene oxide added, and from the standpoint of detergency, a number ranging from 2 to 15 is desirable. R' indicates a hydrogen atom, methyl group or ethyl group. For example, from the standpoints of economy and detergency, an ethylene oxide (2 to 15 mol) adduct of a higher alcohol with 9 to

16 carbon atoms, or an ethylene oxide (2 to 15 mol) propylene oxide (2 to 15 mol) adduct of a higher alcohol with 9 to 16 carbon atoms, is especially desirable for use.

The amount of this component (D) that is added to the composition is selected from a range of 0.4 to 2 mass% of the composition. In cases where this amount is less than 0.4 mass%, the composition is inferior in terms of detergency. On the other hand, even if the amount added exceeds 2 mass%, no improvement in detergency is seen, and such a large amount is economically disadvantageous. From the standpoints of detergency and economy, it is desirable that the amount of the abovementioned surfactant that is added be in the range of 0.4 to 2 mass% based on the total weight of the composition.

Examples of carbonates that can be used as component (E) in the present invention include carbonates, hydrogencarbonates and sesquicarbonates. A single carbonate may be used, or two or more such carbonates may be used in combination. Examples of salts that can be used include sodium salts, potassium salts, amine salts and ammonium salts; in particular, sodium salts are especially desirable.

Component (E) is added in order to improve the bleaching power and detergency; the amount added is selected from a range of 10 to 30 mass% of the composition. In cases where the amount added is less than 10 mass%, there is a lack of improvement in the bleaching power and detergency. On the other hand, in cases where the amount added exceeds 30 mass%, bonding with calcium ions occurs as a result of the balance with other components, so that scale tends to be formed. From the standpoints of detergency and economy, it is desirable that the amount of the abovementioned carbonate that is added be in the range of 10 to 25 mass% based on the total weight of the composition.

Furthermore, in addition to the respective components described above, detergent builders, e. g. , organic carboxylic acids such as citric acid, malic acid, tartaric acid, maleic acid, fumaric acid, succinic acid, gluconic acid or the like, and/or

salts thereof, sulfates, chelating agents and the like, as well as coloring agents, fragrances, preservatives, enzymes and the like, may be added to the composition of the present invention if necessary in amounts that do not adversely affect the object of the present invention.

In the bleaching and cleaning of dishes, cooking utensils and the like, the composition of the present invention is used as an aqueous solution diluted with tap water at a temperature of 30 to 60°C. At temperatures below 30°C, the bleaching power and detergency drop, while at temperatures exceeding 60°C, there is a deficiency in the working characteristics of bleaching and cleaning, and there is also a danger of burn injury. The composition of the present invention is used as an aqueous solution with a concentration of 0.08 to 2 mass% according to the amounts of colored contaminants and food contaminants adhering to the object of cleaning. It is desirable that the available oxygen concentration in this case be 2.5 to 17%. [The object of cleaning] is subjected to bleaching and cleaning by immersion for 10 minutes to 2 hours (in accordance with the amounts of colored contaminants and food contaminants adhering to the object of cleaning) in the aqueous solution of the composition thus prepared. Furthermore, it is desirable that the pH of the aqueous solution in this case be weakly alkaline to alkaline; in particular, a pH of approximately 10 to 11 is desirable from the standpoint of the stability of the available oxygen. The same is true in cases where enzymes are added to the composition of the present invention.

Examples The present invention will be described in detail below by means of examples and comparative examples for the powder bleach detergent composition of the present invention.

(1) Preparation of Test Bleach Detergent Compositions 1 The bleach detergent compositions of Examples 1 through 20 and Comparative Examples 1 through 7 shown in Tables 1 through 4 were prepared and subjected to various tests.

Furthermore, the numerical values shown for the various components in the tables are the contents (mass%) of the respective components; the sum of components (A) through (E) and optional components is a total of 100 mass%.

(2) For each bleach detergent composition obtained, the test items of bleaching power, detergency, scale formation inhibiting power, corrosion preventing properties, stability of available oxygen in aqueous solution and storage stability were evaluated using the test methods and evaluation criteria described below. The results obtained are shown in Tables 1 through 4.

(2-1) Bleaching Power 1 Test Method A teacup equipped with a tea sieve was immersed for 1 hour in a solution of each composition (water temperature 40°C) adjusted to a concentration of 1 mass% using tap water. After rinsing with water and drying, the results were evaluated using the following criteria.

Evaluation Criteria Tea sieve contamination completely removed.

O : Tea sieve contamination almost completely removed.

A : Slight tea sieve contamination observed. x : Almost all tea sieve contamination [still] visible.

(2-2) Detergency 1 Test Method Oily contamination: A mixed oil in which soybean oil and beef tallow were mixed at a weight ratio of 1 : 1 was prepared by heating under agitation for 10 hours at 220°C. After this oil was cooled to approximately 50°C, 0.3 g of the oil was placed on a stainless steel plate test piece, and was uniformly spread on the test piece, after which the oil was solidified by being allowed to stand for 2 hours.

Test pieces prepared as described above were immersed for 10 minutes in 200 ml of a solution of each composition (water temperature 40°C) adjusted to a concentration of 1 mass% using

tap water. Afterward, the test pieces were removed, rinsed with clean water and naturally dried. The cleaning power was evaluated using the following criteria on the basis of visual observation and the weight of contaminants removed.

Evaluation Criteria 0 : 90% or more removed.

O : 70% or more removed.

A : 50% or more removed. x : Less than 50% removed.

(2-3) Scale Formation Inhibiting Power 1 Test Method 380 mg of magnesium sulfate heptahydrate, 732 mg of sodium hydrogencarbonate and 494 mg of calcium chloride were dissolved in 2000 ml of distilled water, thus preparing artificial hard water with a concentration of 300 ppm. Solutions of the respective compositions prepared with a concentration of 1 mass% using this artificial hard water were placed in glass jars, and were held in these jars for 5 hours at an aqueous solution temperature of 70°C. After cooling overnight at room temperature, the aqueous solutions in the glass jars were discarded, and the glass jars were rinsed with water. The conditions of the inside walls of the glass jars were observed by visual inspection, and the feeling of the glass jars when touched with the fingertips was evaluated according to the following criteria: Evaluation Criteria Absolutely no adhesion of scale to the inside walls of the glass jars observed.

O : Almost no adhesion of scale to the inside walls of the glass jars was observed by visual inspection; however, the inside walls had a rough feeling when touched with the fingertips.

A : Adhesion of scale to the inside walls of the glass jars was observed by visual inspection. x : Adhesion of scale loathe inside walls of the glass jars was conspicuously evident.

(2-4) Corrosion Preventing Properties

Test Method Stainless steel (SUS 410) pieces polished with #400 sandpaper were immersed for 10 hours at a water temperature of 70°C in solutions of the respective compositions prepared with a concentration of 1 mass% using tap water. After removal, the test pieces were rinsed with water; then, discoloration of the surface of the stainless steel pieces was observed, and was evaluated according to the following criteria: Evaluation Criteria Almost no discoloration observed on the stainless steel surfaces.

0 : Slight discoloration observed on the stainless steel surfaces.

A : Discoloration observed on the stainless steel surfaces. x : Clear discoloration and corrosion observed on the stainless steel surfaces.

(2-5) Stability of Available Oxygen in Aqueous Solution Test Method Solutions of the respective compositions prepared with a concentration of 1 mass% using tap water were maintained at a water temperature of 60°C, and the available oxygen concentration was measured immediately following dissolution, and after 3 hours had elapsed. The stability of the available oxygen was calculated using the following formula: Stability of available oxygen in aqueous solution (%) = (available oxygen concentration after 3 hours)/ (available oxygen concentration immediately following dissolution) x 100 Evaluation Criteria Stability of available oxygen 90% or greater O : Stability of available oxygen 75% or greater A : Stability of available oxygen 60% or greater x : Stability of available oxygen less than 60% (2-6) Storage Stability Test Method

50 g of each composition was placed in a 100-ml cylindrical styrol jar with pinholes, and was stored for two weeks at 40°C, 75 RH. The available oxygen concentration was measured before and after storage. The stability of the available oxygen concentration was calculated using the following formula: Evaluation Criteria Storage stability (%) = (available oxygen concentration after storage for two weeks)/ (available oxygen concentration before storage) x 100 Stability of available oxygen 90% or greater O : Stability of available oxygen 80% or greater A : Stability of available oxygen 50% or greater x : Stability of available oxygen less than 50% Table 1 Example Example Example Example Example Example Example 1 2 3 4 5 6 7 Sodium perborate Sodium percarbonate 75. 0 75. 0 75. 0 75. 0 75. 0 75. 0 75. 0 PHAS 0. 6 0. 3 1. 0 2. 5 0. 3 0. 6 1. 0 Hom=polymer 1.0 5.0 copolymer 2.0 2.0 1.5 0.5 2.0 2.0 Anionic surfactant 1 Anionic surfactant 2 Nonionic surfactant 1. 0 1.0 0.4 2.0 1 Nonionic surfactant 1.0 2 Nonionic surfactant 1. 0 3 Nonionic surfactant 1.0 4 Sodium carbonate 21. 4 20. 7 21. 5 10. 5 18. 7 22. 0 20. 0 Sodium 10. 5 hydrogencarbonate Sodium Citrate Sodium gluconate Sodium sulfate TAED Bleaching power 1 Detergency 1 Scale formation # # # # # # # inhibiting power 1 Corrosion resistance Stability of available oxygen in aqueous solution Storage stability Table 2 Example Example Example Example Exanple Example Example 8 9 10 11 12 13 14 Sodium perborate Sodium percarbonate 75.0 75.0 75.0 40.0 60.0 60.0 85. 0 PHAS 0.6 0.6 1.5 0.3 0.6 2.0 0.8 Homopolymer Copolymer 2. 0 2.0 0.5 3.0 2.0 0.5 1.0 Anionic surfactant 1 1. 7 1.7 Anionic surfactant 2 1.9 Nonionic surfactant 0. 5 1.0 1.0 1.0 1 Nonionic surfactant 1.0 1.0 2 Nonionic surfactant 3 Nonionic surfactant 4 Sodium carbonate 10.0 19.0 30.0 10.0 30.0 Sodium 20. 7 10.0 hydrogencarbonate Sodium citrate 3.0 Sodium gluconate 5.0 Sodium sulfate 10.0 20.7 26.4 4.8 2.2 TAED Bleaching power 1 (3 (9 0 Detergency 1 0 Scale formation 0 inhibiting power 1 Corrosion resistance 0 0 (3 0 0 0 0 Stability of available oxygen in 0 (3 Q3 # (3 (3 Q3 aqueous solution Storage stability 0 0 Q3 (3 (3 Q3 Q3 Table 3 Example Example Example Example Example Example 15 16 17 18 19 20 Sodium perborate 25. 0 25. 0 25. 0 40. 0 60. 0 75. 0 Sodium percarbonate 50.0 PHAS 0.6 0.3 2.0 0.6 0.6 0.6 Homopolymer 3.0 0.5 Copolymer 2.0 2.0 2.0 2.0 2.0 Anionic surfactant 1 0. 7 Anionic surfactant 2 Nonionic surfactant 1 1.0 1.0 0.4 1.0 1.0 Nonionic surfactant 2 Nonionic surfactant 3 1. 0 Nonionic surfactant 4 Sodium carbonate 21. 4 25.0 10.0 20.0 21.4 21.4 Sodium hydrogencarbonate 20.0 Sodium citrate 10.0 Sodium gluconate Sodium sulfate 43. 7 31. 5 36. 3 15. 0 TAED Bleaching power 1 # # # # Detergency 1 # # # Scale formation inhibiting power 1 Corrosion resistance Stability of available oxygen in aqueous solution Storage stability Table 4 Comparative Comparative Comparative Comparative Comparative Comparative Comparat4ive Example 12 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Sodium perborate Sodium 75. 0 75. 0 75. 0 75. 0 75. 0 75. 0 70. 0 percarbonate PHAS 1.0 .0 1.0 1.0 '0. 5 0. 5 Copolymer 2.0 1.5 2.0 2.0 Anionic surfactant 1 Anionic surfactant 2 Nonionic 1.0 1.0 1.0 1.0 1.0 surfactant 1 Nonionic surfactant 2 Nonionic 2.0 surfactant 3 Nonionic surfactant 4 Sodium 22. 0 17. 0 14. 0 23. 0 22. 0 5. 0 11. 5 carbonate Sodium 10.0 hydrogencarbo nate Sodium 5. 0 citrate Sodium gluconate Sodium 16.0 sulfate Taud 15. 0 Bleaching # # # # # # # power 1 Detergency 1 # # # # # # # Scale # # # # # # # formation inhibiting power 1 korrosion 0 # # # # # x resistance Stability of x x x available oxygen in aqueous solution storage # # # # # # # stability

Furthermore, the components shown in the tables are as described below, and are the same in Tables 1 through 6.

*Sodium perborate: Product with available oxygen content of 15% *Sodium percarbonate: Product with available oxygen content of 11% *PHAS: Sodium poly-a-hydroxyacrylate *Homopolymer: Sodium polyacrylate (average molecular weight 8,000) *Copolymer: Sodium salt of acrylic acid/maleic acid copolymer (partially neutralized) (average molecular weight 70,000) *Anionic surfactant 1: Sodium alkanesulfonate (manufactured by Clariant Japan K. K. /product name: Hostapur SAS60/secondary sodium alkanesulfonate with 12 to 16 carbon atoms, purity 60%) *Anionic surfactant 2: Sodium alkyl ether sulfate (manufactured by Toho Kagaku K. K. /product name: Alscope TH-330/sodium polyoxyethylene (3) lauryl ether sulfate, purity 26%) *Nonionic surfactant 1: Polyoxyalkylene alkyl ether (manufactured by Daiichi Kogyo Seiyaku K. K. /product name: Noigen LP-100/ethylene oxide and propylene oxide adduct of natural higher alcohols) *Nonionic surfactant 2: Polyoxyethylene alkyl ether (manufactured by Shell Japan K. K. /product name: Neodol 91- 8/ethylene oxide (8 mol) adduct of alcohols with 9 to 11 carbon atoms) *Nonionic surfactant 3: Polyoxyethylene alkyl ether (manufactured by Nippon Shokubai K. K. /product name: Softanol 90/ethylene oxide (9 mol) adduct of secondary alcohols with 12 to 14 carbon atoms) *Nonionic surfactant 4: Polyoxyethylene alkylphenyl ether (manufactured by Daiichi Kogyo Seiyaku K. K. /product name: Noigen EA-120/polyoxyethylene nonylphenyl ether)

*TAED: Tetraacetylethylenediamine Furthermore, in order to describe the present invention in detail, the results obtained when the bleach detergent composition was diluted with hard water will be described.

(3) Preparation of Test Bleach Detergent Compositions 2 The bleach detergent compositions of Examples 21 through 26 and Comparative Examples 8 through 12 shown in Tables 5 and 6 were prepared and subjected to various tests.

Furthermore, the numerical values shown for the various components in the tables are the contents (mass%) of the respective components; the sum of components (A) through (E) and optional components is a total of 100 mass%.

Furthermore, the anionic surfactants and nonionic surfactants in the examples and comparative examples shown in the tables are the same as those shown in Tables 1 through 4.

(4) For each bleach detergent composition obtained, the test items of bleaching power, detergency and scale formation inhibiting power were evaluated using the test methods and evaluation criteria described below. The results obtained are shown in Tables 5 and 6.

(4-1) Bleaching Power 2 Preparation of Contaminated Cloth 20 g of powdered tea was placed in 1000 ml of tap water, and was boiled for one hour. Afterward, this solution was filtered with gauze and cooled to room temperature, thus producing a green tea solution. Meanwhile, a saturated aqueous solution of calcium hydroxide was prepared and used as a fixing solution. A #60 cotton broad cloth was immersed for 5 minutes in the green tea solution, and was then immersed for 5 minutes in the fixing solution. Afterward, this cloth was rinsed with water and dried.

This process was repeated three times, thus producing a green tea contaminated cloth.

Test Method Preparation of artificial hard water: 380 mg of magnesium sulfate heptahydrate, 732 mg of sodium hydrogencarbonate and 494

mg of calcium chloride were dissolved in 2000 ml of distilled water, thus preparing artificial hard water with a concentration of 300 ppm.

Preparation of artificial hard water containing iron ions: 5 mg of ferric ammonium sulfate was dissolved in the abovementioned artificial hard water, thus producing artificial hard water containing iron ions.

Samples (5 cm x 5 cm) of the green tea contaminated cloth prepared as descried above were immersed for 3 minutes in 500 ml of a solution of each composition (water temperature 60°C) prepared with a concentration of 1 mass% using the artificial hard water or artificial hard water containing iron ions prepared as described above, or using distilled water. Afterward, the samples were removed, rinsed with water, and naturally dried.

The degree of whiteness was measured using a color difference meter, and the bleaching rate was determined using the following formula: Calculation of Bleaching Power Bleaching rate (%) = (degree of whiteness following bleaching- degree of whiteness before bleaching)/ (degree of whiteness before contamination-degree of whiteness before bleaching) x 100 The results were evaluated using the following criteria: Bleaching rate of 80% or greater O : Bleaching rate of 65% or greater A : Bleaching rate of 50% or greater x : Bleaching rate of less than 50% (4-2) Detergency 2 Test Method Oily contamination: A mixed oil in which soybean oil and beef tallow were mixed at a weight ratio of 1 : 1 was prepared by heating under agitation for 10 hours at 220°C. After this oil was cooled to approximately 50°C, 0.3 g of the oil was placed on a stainless steel plate test piece, and was uniformly spread on

the test piece, after which the oil was solidified by being allowed to stand for 2 hours.

Egg contamination: Raw eggs were separated into egg yolks and egg whites, and these substances were filtered using gauze.

The filtered egg yolks and egg whites were mixed at a ratio of 4 : 6.0. 6 g of this mixture was placed on stainless steel plate test pieces, and was uniformly spread; this mixture was then solidified by allowing the mixture to stand for 3 hours at room temperature.

Starch contamination: High-grade fresh flour and distilled water were mixed at a weight ratio of 1 : 9, and this mixture was formed into a paste by heating under agitation for 30 minutes at 70°C. 0.6 g of this paste was placed on stainless steel plate test pieces, and was uniformly spread, after which the paste was dried by allowing the paste to stand at room temperature for 3 hours.

Preparation of artificial hard water: 380 mg of magnesium sulfate heptahydrate, 732 mg of sodium hydrogencarbonate and 494 mg of calcium chloride were dissolved in 2000 ml of distilled water, thus preparing artificial hard water with a concentration of 300 ppm.

The three types of test pieces prepared as describe above were separately immersed for specified periods of time in 200 ml of solutions of the respective compositions (water temperature 40°C) prepared with a concentration of 1 mass% using the artificial hard water prepared as described above, or using distilled water. The immersion times were 10 minutes in the case of oily contamination and egg contamination, and 20 minutes in the case of starch contamination. Afterward, the samples were removed, rinsed with clean water and naturally dried. The detergency was evaluated using the following criteria on the basis of the weight of the contaminants removed and observation by visual inspection.

Evaluation Criteria @ : 90% or more removed.

O : 70% or more removed.

A : 50% or more removed. x : Less than 50% removed.

(4-3) Scale Formation Inhibiting Power 2 Test Method Following the completion of the detergency test of (4-2), the samples were allowed to stand overnight at room temperature until cool. The aqueous solutions in the glass jars were discarded, and the glass jars were rinsed with water. The conditions of the inside walls of the glass jars were observed by visual inspection, and the feeling of the glass jars when touched with the fingertips was evaluated according to the following criteria: Evaluation Criteria Absolutely no adhesion of scale to the inside walls of the glass jars observed.

O : Almost no adhesion of scale to the inside walls of the glass jars was observed by visual inspection; however, the inside walls had a rough feeling when touched with the fingertips.

A : Adhesion of scale to the inside walls of the glass jars was observed by visual inspection. x : Adhesion of scale to the inside walls of the glass jars was conspicuously evident.

Table 5 Example Example Example Example Example Example 21 22 23 24 25 26 Sodium perborate 30. 0 40. 0 Sodium percarbonate 75.0 75.0 75.0 60.0 45.0 PHAS 1. 0 0. 3 2. 5 0. 6 0. 3 0. 6 Homopolymer 0. 5 5.0 Copolymer 1. 5 2. 0 1. 0 2. 0 2. 0 Anionic surfactant 1 1.7 Anionic surfactant 2 Nonionic surfactant 1 1.0 1.0 Nonionic surfactant 2 1.0 Nonionic surfactant 3 1.0 Nonionic surfactant 4 1.0 Sodium carbonate 21.0 20.0 10.5 18. 7 25.0 Sodium hydrogencarbonate 30. 0 Sodium citrate 3.0 Sodium gluconate Sodium sulfate 1. 7 10. 0 2.7 31. 4 Bleaching power 2 Distilled water Artificial hard water Artificial hard water containing iron ions Detergency 2 Oily contamination ; Distilled water Oily contamination ; Artificial hard water Starch contamination ; Distilled water Starch contamination ; Artificial hard water Egg contamination ; Distilled water Egg contamination ; Artificial hard water Scale formation inhibiting power 2 Table 6 Comparative Comparative Comparative Comparative Comparative Example 8 Example 9 Example 10 Example 11 Example 12 Sodium perborate Sodium 75.0 75.0 75.0 75.0 75.0 percarbonate PHAS 1.0 1.0 1.0 Homopolymer 0.5 Copolymer 1.5 2.0 2.0 Anionic surfactant 1 Anionic 3.8 surfactant 2 Nonionic 1.0 2.0 surfactant 1 Nonionic 1.0 surfactant 2 Nonionic surfactant 3 Nonionic surfactant 4 Sodium 22. 0 24. 0 15. 2 19. 0 5. 0 carbonate Sodium hydrogencarbo nate Sodium 3.0 citrate Sodium 5.0 gluconate Sodium 3. 0 12.0 sulfate Bleaching power 2 Distilled O water Artificial 0 A O A A hard water Artificial hard water containing irons Detergency 2 Oily x O contaminat ion; Distilled water oily x x A x A contaminat ion; Artificial hard water Starch A A O A A contaminat ion; Distilled water Starch x x x x A contaminat ion; Artificial hard water Egg A A A 0 contaminat ion; Distilled water Egg # # # # # contaminat ion; Artificial hard water Scale x x x OO OO formation inhibiting power 2

It is seen that in Examples 1 through 26, which constitute powder bleach detergent compositions according to the present invention, the compositions showed good performance in all of the test items of bleaching power, detergency, scale formation inhibiting power, corrosion preventing properties, stability of available oxygen in aqueous solution and storage stability.

Comparative Examples 1 through 3 and Comparative Examples 8 and 9 are examples in which the composition contains no poly-a- hydroxyacrylate. It is seen from Comparative Examples 1 through 3 that there are problems in terms of storage stability and

stability of the available oxygen in aqueous solution, and that a sufficient effect cannot be exhibited in the case of immersion bleaching of dishes, cooking utensils or the like. Furthermore, it is also seen that the detergency is insufficient. Moreover, it is seen from Comparative Examples 8 and 9 that the bleaching power is inferior in cases where iron ions are present in the aqueous solution, and that the scale formation inhibiting power is inferior in cases where contaminant components are present in the aqueous solution following the detergency test.

Comparative Examples 3 and 4 and Comparative Examples 9 and 10 are examples in which no polyacrylate or salt of a copolymer of polyacrylic acid and maleic acid is present in the composition.

It is seen that the scale formation inhibiting power is inferior in such cases. In particular, in Comparative Examples 9 and 10, it is seen that the formation of scale is conspicuous in cases where contaminant components are present in the aqueous solution following the detergency test, so that the compositions are inadequate for practical use.

Comparative Example 5 and Comparative Example 11 are examples in which the composition contains no surfactant; it is seen that the bleaching power and detergency are inferior in such cases. Furthermore, Comparative Example 6 and Comparative Example 12 are examples in which the carbonate content is less than 10 mass% ; it is seen that the bleaching power and detergency are inferior in such cases. Comparative Example 7 is an example of a conventional bleach composition containing a bleach activating agent (tetraacetylethylenediamine); it is seen that the addition of a bleach activating agent to the product of the present invention results in a drop in the scale formation inhibiting power and the properties that prevent corrosion of the object of cleaning.

The powder bleach detergent composition of the present invention is suitable for use in the bleaching of dishes, cooking utensils and the like. This composition is superior in terms of storage stability of the composition and stability of the

available oxygen in aqueous solution. In addition, this composition is superior in terms of scale formation inhibiting power and properties that prevent corrosion of the object of cleaning; moreover, this composition is superior in terms of bleaching power and detergency, regardless of the amounts of hard components such as calcium, magnesium and the like contained in the aqueous solution.