JP7292849B2 - Liquid detergent composition for automatic dishwasher - Google Patents

Description

TECHNICAL FIELD The present invention relates to a liquid detergent composition for automatic dishwashers and a method for washing dishes with an automatic dishwasher using the same.

2. Description of the Related Art Conventionally, automatic dishwashers have been widely used in hotels, restaurants, catering companies, hospitals, company cafeterias, etc., in order to efficiently wash tableware, cooking utensils, and the like after use. In addition, automatic washing machines are used not only in food processing plants but also in various manufacturing plants and processing plants to wash utensils, containers, plastic containers used for distribution, and the like.
These automatic washing machines need to wash a large number of dishes in a short time, so it is common to use a strong alkaline agent for washing. It has been proposed to use powder detergents or solid detergents that are easy to mix. Patent Document 1 discloses a technique for a solid detergent containing an alkali metal hydroxide, and the composition described in the publication also contains large amounts of carbonates and silicates.

On the other hand, the technology of a liquid-type cleaning agent that is more convenient to use has been researched in recent years. Patent Document 2 discloses (A) a polymer compound having a weight average molecular weight of 5,000 to 100,000 and containing a structural unit derived from a cationic monomer, (B) methylglycine diacetate, glutamine diacetate, or and (C) citric acid or a salt thereof, and water. Patent Document 3 discloses a liquid detergent composition for dishwashers containing a silicate, comprising (A) methylglycine diacetate, glutamine diacetate or salts thereof, (B) citric acid or a salt thereof, ( C) contains polyacrylic acid or a salt thereof and water, further contains 2.5 to 7.4% by mass of silicate, contains potassium ions and optionally sodium ions, and contains sodium ions [Na ⁺ ] to the content of potassium ions [K ⁺ ] is disclosed is a liquid detergent composition for dishwashers, wherein the molar ratio [Na ⁺ ]/[K ⁺ ] is 0 to 0.9.

JP 2010-144087 A JP 2016-27102 A Japanese Patent No. 5719077

The liquid detergent compositions for dishwashers described in Patent Documents 1 and 2 are excellent in detergency and scale adhesion inhibitory properties. However, in places such as restaurants and catering companies where a large amount of tableware needs to be washed, the load of washing dirt is heavy, and a washing method that operates at high temperature for a long time is adopted. In such a situation, these liquid detergent compositions for dishwashers satisfies the accumulation of scale caused by repeated adhesion of scale due to hardness components from tap water and well water in automatic dishwashers. The present inventors have found that further improvements are needed to suppress it to the level possible. In particular, when water with a hardness component exceeding 7.5°dH is used, scale builds up significantly in the automatic dishwasher. There is a strong need for technology that suppresses accumulation.

In liquid detergent compositions for dishwashers, a method of reducing carbonate, which is a scale component, is conceivable in order to suppress the accumulation of scale in automatic dishwashers. It is not possible to suppress the build-up of scale when using In addition, the expected detergency also decreases. Accordingly, there is a strong demand for a liquid detergent composition that achieves both detergency and scale accumulation suppression in automatic dishwashers that operate at high temperatures for a long period of time using high-hardness water.

The present invention has high detergency even when the automatic dishwasher uses high-hardness water for a long time at high temperature and is excellent in inhibiting the accumulation of scale in the automatic dishwasher. Provided are a liquid detergent composition for automatic dishwashing machines, which has good storage stability at low temperatures (eg, -5°C), and a method for washing dishes with an automatic dishwashing machine using the same.

The scale of the present invention suppresses the adhesion of scale when washed with normal hardness water, and has scale releasability such that the adhered scale can be easily removed even when washed with high hardness water. Provided is a liquid detergent composition for automatic dishwashing machines, which is excellent in suppressing accumulation.
That is, the present invention comprises (a) 3.0% by mass or more and 20% by mass or less of acid conversion of one or more selected from citric acid, gluconic acid, and salts thereof; A liquid detergent composition for automatic dishwashers, comprising less than 0% by weight, (c) less than 1.0% by weight of an alkali metal carbonate, and water,
The content of alkali metal ions in the composition is 5.0% by mass or more and 19% by mass or less, and an aqueous solution obtained by diluting the composition to 0.2% by mass with water has a pH of 10.0 or more at 25°C. 12.5 or less, it relates to a liquid detergent composition for automatic dishwashers.

The present invention also relates to a method for washing dishes, comprising repeating the following steps 1 and 2 using a washing liquid obtained by diluting the liquid detergent composition for automatic dishwashers with water.
Step 1: A step of washing dishes housed in a washing chamber of an automatic dishwasher for 20 seconds or more and 120 seconds or less with the washing liquid having a washing temperature of 50°C or more and 70°C or less Step 2: After step 1, 50°C or more and 80°C The process of rinsing the tableware with the following water for 4 seconds or more and 10 seconds or less

According to the present invention, even when the automatic dishwasher is operated with high-hardness water at a high temperature for a long time, it has a high detergency and is capable of suppressing scale accumulation in the automatic dishwasher. Provided are a liquid detergent composition for automatic dishwashers, which is excellent and has good storage stability at low temperatures (e.g., -5°C), and a method for washing dishes with an automatic dishwasher using the same. .

[Liquid detergent composition for automatic dishwasher]
<(a) component>
The component (a) of the present invention is one or more selected from citric acid, gluconic acid, and salts thereof. Examples of the salt of component (a) include alkali metal salts and alkaline earth metal salts, and from the viewpoint of the ability to suppress scale accumulation, alkali metal salts are preferred, and sodium salts and potassium salts are more preferred. Potassium salts are more preferred.
When the component (a) is used in the form of a salt, the salt of the component (a) is incorporated into the liquid detergent composition of the present invention, or the component (a) is added in the form of an acid to the liquid detergent of the present invention. After being contained in the composition, it can be neutralized with an alkali agent such as an alkali metal hydroxide, which is the component (g) below, and then contained.
The component (a) of the present invention is preferably citric acid or a salt thereof from the viewpoint of scale accumulation suppressing ability.
In the liquid detergent composition for automatic dishwashing machines of the present invention, after containing citric acid and/or gluconic acid as component (a), it is neutralized with potassium hydroxide as component (g) below. It is also preferable to contain potassium citrate and/or potassium gluconate itself as the component (a).

<(b) component>
Component (b) is a water-soluble silicate. The water-soluble silicate refers to a silicate that dissolves 10 g or more in 100 g of distilled water at 25°C.

(b) As a silicate of a component, 1 or more types chosen from an alkali-metal silicate are mentioned. Alkali metal silicates include one or more selected from metasilicates, orthosilicates, and mixtures of silicon dioxide and alkali metal oxides. The mixture of silicon dioxide and alkali metal oxide includes one or more selected from No. 1 silicate, No. 2 silicate, No. 3 silicate and No. 4 silicate. Here, the alkali metal silicate is represented by the formula M ₂ O·n SiO ₂ (M is an alkali metal, n is the molar ratio SiO ₂ /M ₂ O), and the No. 1 silicate has an average molar ratio n of Silicates with a molar ratio n of 1.7 or more and 2.3 or less, No. 2 silicates with an average molar ratio n of 2.4 or more and 2.7 or less, and No. 3 silicates with an average molar ratio n of The silicate having a molar ratio n of 2.8 to 3.3 and No. 4 silicate are silicates having an average molar ratio n of 3.7 to 3.9. Salts include one or more selected from sodium salts and potassium salts.

Component (b) is preferably one or more selected from orthosilicates and mixtures of silicon dioxide and alkali metal oxides, from the viewpoint of blending stability. One or more selected from silicates and metasilicates are more preferable, and one or more selected from orthosilicates and No. 1 silicates are more preferable from the viewpoint of scale accumulation suppression properties.

<(c) component>
Component (c) is an alkali metal carbonate. Component (c) includes one or more selected from potassium carbonate and sodium carbonate, and potassium carbonate is preferred from the viewpoint of scale accumulation suppressing ability.

The liquid detergent composition for automatic dishwashers of the present invention contains alkali metal ions. Alkali metal ions include one or more selected from potassium ions and sodium ions.
Alkali metal ions are components (a), (b), (c), and the following optional components (d), (e), (f), and (g). It is derived from salt.

<Composition, etc.>
Although the action mechanism of the present invention has not been elucidated in detail, the present inventors believe as follows. Well water and tap water with high hardness contain a large amount of calcium ions. When such water is used for washing with an automatic dishwasher, the washing liquid contains carbonate as an alkaline agent for the purpose of improving detergency, so calcium carbonate scale adheres and accumulates inside the automatic dishwasher. do. For the purpose of solving such problems, conventionally, techniques have been developed to contain a large amount of a chelating agent having a high pKca. However, even with such a technique, a sufficiently satisfactory effect cannot be obtained when high hardness water exceeding 7.5° dH, for example, is used as washing water.
Instead of capturing calcium ions in high hardness water with a chelating agent, the present inventors used the component (a) of the present invention to actively precipitate them as crystals of calcium salts of citric acid or gluconic acid. We believe that it is possible to suppress the adhesion of scale to the inside of an automatic dishwasher, and even if it adheres, it becomes easier to peel off, and as a result, it is possible to suppress the accumulation of scale.
There are also calcium carbonate formed from carbon dioxide in the air from calcium in high-hardness water, and calcium carbonate formed when a washing liquid containing carbonate as an alkaline agent in addition to the component (a) of the present invention is used. It adheres to the inside of an automatic dishwashing machine and becomes scale. In this case, crystals of calcium salt of citric acid or gluconic acid coexist at the same time between crystals of calcium carbonate. When calcium carbonate and a calcium salt of citric acid or gluconic acid coexist, the calcium salt of citric acid or gluconic acid coexists in scale together with calcium carbonate. When the calcium salt of citric acid or gluconic acid coexisting in such scale is brought into contact with the cleaning liquid of the present invention, the calcium salt of citric acid or gluconic acid dissolves in the cleaning liquid, and along with this, the accumulated scale becomes easier to peel off. Conceivable.
Therefore, in the present invention, the water-soluble silicate as component (b) and the alkali metal carbonate as component (c) in the detergent composition are reduced as much as possible within a range that does not affect the cleaning effect, and component (a) is used. By positively forming a calcium salt of citric acid or gluconic acid by , the dissolution and / or exfoliation of scale adhered in the automatic dishwasher can be promoted, and thus the suppression of scale accumulation in the automatic dishwasher can be achieved. It is considered to be a thing.

In the liquid detergent composition for automatic dishwashers of the present invention, the component (a), converted to acid, is 3.0% by mass or more, preferably 4.0% by mass or more, from the viewpoint of the ability to suppress scale accumulation. It is preferably 5.0% by mass or more, and from the viewpoint of blendability and low-temperature stability, it is contained in an amount of 20% by mass or less, preferably 18% by mass or less, and more preferably 16% by mass or less.

The liquid detergent composition for automatic dishwashing machines of the present invention contains component (b) in an amount of less than 1.0% by mass, preferably 0.8% by mass or less, more preferably 0.8% by mass or less, from the viewpoint of ability to suppress scale accumulation. It contains 6% by mass or less. Moreover, in the liquid detergent composition for automatic dishwashers of this invention, 0 mass % may be sufficient as content of (b) component.

The liquid detergent composition for automatic dishwashing machines of the present invention contains component (c) in an amount of less than 1.0% by mass, preferably 0.8% by mass or less, more preferably 0.8% by mass or less, from the viewpoint of the ability to suppress scale accumulation. It contains 6% by mass or less. Moreover, in the liquid detergent composition for automatic dishwashers of this invention, 0 mass % may be sufficient as content of (c) component.

The liquid detergent composition for automatic dishwashers of the present invention contains alkali metal ions in an amount of 5.0% by mass or more, preferably 6.0% by mass or more, more preferably 7.0% by mass or more, from the viewpoint of further improving detergency. 0% by mass or more, more preferably 8.0% by mass or more, still more preferably 9.0% by mass or more, and from the viewpoint of blendability and low temperature stability, 19% by mass or less, preferably 18% by mass or less, More preferably, the content is 17% by mass or less.

The liquid detergent composition for automatic dishwashers of the present invention further contains an aminocarboxylic acid-type sequestering agent having a pKca of 5 or more and 14 or less at 25° C. and pH 10 as the component (d) from the viewpoint of suppressing adhesion of tea stains. It can be contained within a range that does not impair the effects of the present invention.

The pKca of component (d) at 25° C. and pH 10 is preferably 6 or more, more preferably 6.3 or more, and preferably 13 or less from the viewpoint of suppressing tea stain adhesion.

In the present invention, pKca is a calcium stability constant (Ca stability constant) and can be measured by the following method.
<Method for measuring pKca>
A 0.1 mol/liter NH ₄ Cl—NH ₄ OH (pH 10.0) solution is prepared as a buffer. This buffer is used to prepare all sample solutions. Also, the temperature of these sample solutions is set to 25° C. for the measurement. As an example, an ion meter 920A and a Ca ²⁺ ion electrode manufactured by Orion Co., Ltd. can be used to measure the Ca ²⁺ concentration.
First, the relationship between the concentration of calcium chloride and the potential of the electrode is obtained, and a calibration curve is created. A 5.36×10 ⁻² mol/L solution of calcium chloride and a 5.36×10 ⁻⁴ mol/L solution of component (d) are prepared. 1 ml of calcium chloride solution is added to 100 ml of the prepared component (d) solution and stirred for 5 minutes. The remaining Ca ²⁺ concentration is measured using a Ca ²⁺ ion electrode. Assuming that the chelating agent forms a chelate complex with Ca ²⁺ at a ratio of 1:1, pKca (calcium stability constant, Ca stability constant) is calculated from the following formula.

(d) Components include methylglycinediacetic acid (MGDA) (6.3), glutamic diacetic acid (GLDA) (6.5), ethylenediaminetetraacetic acid (EDTA) (12.2), and nitrilotriacetic acid (NTA). (6.6), diethylenetriaminepentaacetic acid (DPTA) (10.7), N-hydroxyethyl-ethylenediaminetriacetic acid (HEDTA) (7.2), aspartic diacetic acid (ASDA) (7.0), and these One or more selected from salts of The values in parentheses are the pKca of the compound measured by the method described above. The salt is preferably an alkali metal salt, more preferably a sodium salt or a potassium salt.

Component (d) is preferably one or more selected from methylglycine diacetic acid, glutamic acid diacetic acid, ethylenediaminetetraacetic acid, aspartic acid diacetic acid, and salts thereof, from the viewpoint of suppressing the adhesion of tea stains, and methylglycine diacetic acid and ethylenediamine. Tetraacetic acid and one or more selected from salts thereof are more preferred, and methylglycinediacetic acid or a salt thereof is even more preferred.

The liquid detergent composition for automatic dishwashing machines of the present invention may contain component (d) from the viewpoint of suppressing adhesion of tea stains. should be avoided in large amounts because it may suppress
When the liquid detergent composition for automatic dishwashers of the present invention contains component (d), the content of component (d) in terms of acid is preferably greater than 0% by mass, more preferably 0.5% by mass. Above, more preferably 1.0% by mass or more, and preferably 10% by mass or less, more preferably 9.0% by mass or less, even more preferably 8.0% by mass or less, still more preferably 6.0% by mass Contains:

When the liquid detergent composition for automatic dishwashers of the present invention contains component (d), the mass ratio of the content of component (a) to the content of component (d) (d)/(a) is preferably 0 or more, more preferably 0.1 or more, still more preferably 0.2 or more from the viewpoint of tea stain adhesion, and preferably 1.2 or less, more preferably 1 from the viewpoint of scale accumulation suppression. 0.0 or less, more preferably 0.8 or less, even more preferably 0.6 or less, and even more preferably 0.4 or less. However, both the content of the component (a) and the content of the component (d) are in terms of acid.

The liquid detergent composition for automatic dishwashing machines of the present invention can further contain a surfactant as component (e) from the viewpoint of suppressing adhesion of tea stains.

The surfactant of component (e) may be one or more selected from nonionic surfactants, anionic surfactants, cationic surfactants, and amphoteric surfactants, depending on the purpose. is preferably one or more selected from nonionic surfactants and anionic surfactants, more preferably nonionic surfactants.

Nonionic surfactants are not particularly limited, but examples include polyoxyethylene alkyl ethers, polyoxyethylene polyoxypropylene alkyl ethers, polyoxyalkylene dialkyl ethers, polyoxyethylene alkenyl ethers, polyoxyalkylene alkylphenyl ethers, Pluronic block polymer, tetronic block polymer, reverse pluronic block polymer, reverse tetronic block polymer, sucrose fatty acid ester, sorbitan fatty acid ester, polyethylene glycol fatty acid ester, glycerin fatty acid ester, polyglycerin fatty acid ester, propylene glycol fatty acid ester , polypropylene glycol fatty acid ester, coconut fatty acid diethanolamide, lauric acid diethanolamide, lauric acid myritic acid diethanolamide, myristic acid diethanolamide, oleic acid diethanolamide, palm kernel fatty acid diethanolamide, alkyl glucosides, amine oxides, and the like. In particular, from the viewpoint of washability, polyoxyethylene polyoxypropylene alkyl ether, pluronic block polymer, tetronic block polymer, reverse pluronic block polymer, and reverse tetronic block polymer are preferred. These nonionic surfactants may be used alone or in combination of two or more.

Component (e) of the present invention includes one or more selected from nonionic surfactants represented by the following general formula (e-1) and nonionic surfactants represented by general formula (e-2). and nonionic surfactants represented by the following general formula (e-2').

R ^ld —O—(EO) _p —(PO) _q —(EO) _r —H (e−1)
[In the formula, R ^1d represents a hydrocarbon group having 8 to 18 carbon atoms, EO represents an oxyethylene group, and PO represents an oxypropylene group. p, q, and r each represent an average number of added moles, where p is 1 or more and 10 or less, q is 0.5 or more and 5 or less, and r is 1 or more and 10 or less. "-(EO) _p- (PO) _q- (EO) _r- " is a block bond. ]

R ^2d —O—(EO) _s —(AO) _t —H (e-2)
[In the formula, ^R2d represents a hydrocarbon group having 8 to 18 carbon atoms, EO represents an oxyethylene group, and AO represents an oxypropylene group or an oxybutylene group. s and t each represent the average number of added moles, where s is 1 or more and 20 or less, and t is 0.5 or more and 20 or less. “—(EO) _s —(AO) _t —” is a block bond. ]

R ^2'd -O-(EO) _s1 -(PO) _t1 -H (e-2')
[In the formula, R ^2'd represents a branched alkyl group or a branched alkenyl group having 8 to 18 carbon atoms, EO represents an oxyethylene group, and PO represents an oxypropylene group. s1 and t1 each represent an average added mole number, s1 is 4 or more and 10 or less, t1 is 2 or more and 10 or less, and t1/s1 is 0.3 or more and 1.5 or less. "-(EO) _s1- (PO) _t1- " is a block bond. ]

In general formula (e-1), p is 1 or more, preferably 2 or more, and 10 or less, preferably 8 or less. q is 0.5 or more, preferably 1 or more, and 5 or less, preferably 4.5 or less, more preferably 3 or less, and still more preferably 2 or less. r is 1 or more, preferably 2 or more, and 10 or less, preferably 8 or less. p+r is 2 or more, preferably 3 or more, more preferably 4 or more, and 20 or less, preferably 18 or less, more preferably 16 or less, even more preferably 15 or less. R ^1d is a hydrocarbon group having 8 or more, preferably 10 or more and 18 or less, preferably 14 or less carbon atoms, preferably a linear alkyl group.

Specific examples of nonionic surfactants of general formula (e-1) include polyoxyethylene (3) polyoxypropylene (1.5) polyoxyethylene (3) lauryl ether, polyoxyethylene (5) polyoxy One or more selected from propylene (1.5) polyoxyethylene (5) lauryl ether and polyoxyethylene (5) polyoxypropylene (4.5) polyoxyethylene (5) lauryl ether . Here, regarding the compound, the number in parentheses is the average number of added moles of ethylene oxide or propylene oxide.

In general formula (e-2), R ^2d is a hydrocarbon group having 8 or more carbon atoms and 18 or less, preferably 16 or less, more preferably 14 or less carbon atoms, preferably a linear or branched alkyl group. s is 1 or more, preferably 2 or more, more preferably 3 or more, and 20 or less. t is 0.5 or more, preferably 1 or more, more preferably 2 or more, and 20 or less.
The compound of general formula (e-2) can be synthesized by adding EO to an alcohol having a hydrocarbon group of R ^2d and then adding PO.

In general formula (e-2′), R ^2′d is a branched-chain alkyl group or branched-chain alkenyl group having 8 or more carbon atoms, preferably 10 or more carbon atoms, and 18 or less, preferably 14 or less carbon atoms, preferably It is a secondary alkyl group or a secondary alkenyl group. s1 is 4 or more, preferably 5 or more, and 10 or less, preferably 9 or less. t1 is 2 or more, preferably 5 or more, and 10 or less, preferably 9 or less.
Specific examples of nonionic surfactants of general formula (e-2′) include polyoxyethylene (7) polyoxypropylene (8.5) -sec-dodecyl ether, polyoxyethylene (7) polyoxypropylene (8 5) -sec-tridecyl ether, and polyoxyethylene (7) polyoxypropylene (8.5) -sec-tetradecyl ether. Here, regarding the compound, the number in parentheses is the average number of added moles of ethylene oxide or propylene oxide.
The compound of general formula (e- ² ′) is a branched chain (preferably 2 Class) can be synthesized by adding EO to alcohol and then adding PO.

As the nonionic surfactant of component (e), from the viewpoint of detergency, non-foaming and low-foaming properties, nonionic surfactants represented by the following general formula (e-3) and general formula (e- One or more selected from nonionic surfactants represented by 4) are preferred.
HO-(EO) _a- (PO) _b- (EO) _c -H (e-3)
HO-(PO) _d- (EO) _e- (PO) _f -H (e-4)
[In the formula, EO represents an oxyethylene group, and PO represents an oxypropylene group. a, b, c, d, e and f are the average number of added moles, each independently being 1 or more, preferably 2 or more, more preferably 3 or more, and 350 or less, preferably 200 or less, more preferably is a number less than or equal to 100. ]

In general formulas (e-3) and (e-4), the total of EO and PO preferably contains EO in an amount of 10 mol% or more. It is preferable to select Further, from the viewpoint of low foaming properties, nonionic surfactants represented by general formula (e-4) are more preferable.

In the nonionic surfactants represented by general formulas (e-3) and (e-4), the weight average molecular weight is preferably 200 or more, more preferably 1,000 or more, and preferably 15,000 or less, It is more preferably 6,000 or less, still more preferably 5,000 or less.

Among the above nonionic surfactants, the nonionic surfactant represented by the general formula (e-1) is available from Nippon Shokubai Co., Ltd. under the trade name of "SOFTANOL". The nonionic surfactant represented by general formula (e-2') is available from Kao Corporation under the trade name of "Emulgen". The nonionic surfactant represented by general formula (e-3) is available from ADEKA Corporation under the trade name of "Pluronic". The nonionic surfactant represented by general formula (e-4) is available from BASF under the trade name of "Pluronic R".

The anionic surfactant is preferably one or more selected from alkenylsuccinic acid, fatty acid, and salts thereof, from the viewpoint of further improving detergency and low-foaming properties.

The number of carbon atoms in the alkenyl group of alkenylsuccinic acid is preferably 10 or more, more preferably 12 or more, and preferably 16 or less, more preferably 14 or less, from the viewpoint of further improving detergency and low-foaming properties. The salt of alkenylsuccinic acid is preferably an alkali metal salt, more preferably a sodium salt or a potassium salt.

The carbon number of the fatty acid is preferably 6 or more, more preferably 8 or more, and preferably 12 or less, more preferably 10 or less, from the viewpoint of further improving detergency and low-foaming properties. Salts of fatty acids are preferably alkali metal salts, more preferably sodium salts or potassium salts.

Component (e) is preferably one or more selected from nonionic surfactants represented by general formula (e-3), alkenylsuccinic acid or salts thereof, and fatty acids or salts thereof, from the viewpoint of compatibility.

When the liquid detergent composition for automatic dishwashers of the present invention contains component (e), from the viewpoint of further improving detergency and low-foaming properties, the component (e) is preferably 0.25 mass % or more, more preferably 0.30 mass % or more, still more preferably 0.35 mass % or more, even more preferably 0.5 mass % or more, and 5.0 mass % or less, preferably contains 4.5% by mass or less, more preferably 4.0% by mass or less, even more preferably 3.0% by mass or less, and even more preferably 2.0% by mass or less. However, when an anionic surfactant is contained as the component (e), the content thereof is converted to an acid value.

When the liquid detergent composition for automatic dishwashers of the present invention contains a nonionic surfactant represented by general formula (e-3) as component (e), it further improves detergency and low-foaming properties. From the viewpoint of, the nonionic surfactant represented by the general formula (e-3) is 0.1% by mass or more, preferably 0.2% by mass or more, more preferably 0.3% by mass or more, and blended from the viewpoint of properties, 5.0% by mass or less, preferably 4.5% by mass or less, more preferably 4.0% by mass or less, even more preferably 2.0% by mass or less, and even more preferably 1.0% by mass. Contains:

When the liquid detergent composition for automatic dishwashing machines of the present invention contains alkenyl succinic acid or a salt thereof as component (e), from the viewpoint of further improving detergency and low-foaming properties, alkenyl succinic acid or The salt content is preferably 0.05 mass % or more, more preferably 0.10 mass % or more, and preferably 0.5 mass % or less, more preferably 0.4 mass % or less. The content of alkenyl succinic acid or a salt thereof is a value in terms of acid.

When the liquid detergent composition for automatic dishwashing machines of the present invention contains a fatty acid or a salt thereof as the component (e), the fatty acid or a salt thereof is preferably used from the viewpoint of further improving detergency and low-foaming properties. is 0.1% by mass or more, more preferably 0.2% by mass or more, still more preferably 0.3% by mass or more, and preferably 5.0% by mass or less, more preferably 4.0% by mass or less, and further The content is preferably 3.0% by mass or less, more preferably 2.0% by mass or less, and even more preferably 1.0% by mass or less. Content of fatty acid or its salt is a value of acid conversion.

The liquid detergent composition for automatic dishwashers of the present invention can further contain a carboxylic acid-based polymer as the component (f) from the viewpoint of inhibiting scale accumulation.

The carboxylic acid polymer of component (f) is preferably one or more selected from polyacrylic acid or its salts, polymaleic acid or its salts, and acrylic acid-maleic acid copolymers or its salts, and polyacrylic acid or its salts. is preferred. The salt may be part or all, and the salt is preferably an alkali metal salt, more preferably a sodium salt or a potassium salt.

The weight-average molecular weight of the component (f) is preferably 1,000 or more, more preferably 3,000 or more, and preferably 10, from the viewpoint of further improving scale accumulation inhibition, detergency, and tea stain adhesion inhibition. 000 or less, more preferably 8,000 or less, still more preferably 6,000 or less, and even more preferably 5,000 or less. The weight average molecular weight of component (f) is measured by gel permeation chromatography (GPC method) using polyethylene glycol with known molecular weight as a standard substance.

When the liquid detergent composition for automatic dishwashers of the present invention contains component (f), the content of component (f) is 0.5% by mass or more, preferably 0.5% by mass or more, from the viewpoint of further improving detergency. 7% by mass or more, more preferably 1.0% by mass or more, and 5.0% by mass or less, preferably 4.5% by mass or less, more preferably 4.0% by mass or less, even more preferably 3.0% by mass % or less.

When the liquid detergent composition for automatic dishwashers of the present invention contains components (e) and (f), the content of component (a) and the total content of components (e) and (f) from the viewpoint of blending stability, the mass ratio (a)/[(e)+(f)] is preferably 0.8 or more, more preferably 1.0 or more, and still more preferably 1.5 or more And it is preferably 10.0 or less, more preferably 8.5 or less, still more preferably 7.0 or less. However, the content of component (a) is the content in terms of acid.

When the liquid detergent composition for automatic dishwashers of the present invention contains components (d), (e), and (f), the content of component (d), and the components (e) and (f) ) to the total content of components (d)/[(e)+(f)] is preferably 0 or more, more preferably 0.2 or more, still more preferably 0.2 or more, from the viewpoint of blending stability. 5 or more, and preferably 1.5 or less, more preferably 1.2 or less, and even more preferably 1.0 or less. However, the content of the component (e) (when an anionic surfactant is included as the component (e)) and the content of the component (d) are both acid-equivalent contents.

In the liquid detergent composition for automatic dishwashers of the present invention, the total content of components (a), (d), (e) and (f) is preferably 10.0% by mass or more, more preferably 11.0% by mass or more, still more preferably 12.0% by mass or more, and preferably 40.0% by mass or less, more preferably 37.0% by mass or less, and even more preferably is 35.0% by mass or less, more preferably 30% by mass or less. However, the content of component (a), the content of component (d), and the content of component (e) (when an anionic surfactant is included as component (e)) are all acid-equivalent contents.

The liquid detergent composition for automatic dishwashers of the present invention has the purpose of promoting crystal formation of calcium salt of citric acid or gluconic acid by component (a), further improving detergency, alumite corrosion resistance, and alkali metal ion For the purpose of adjusting the concentration to the predetermined concentration of the present invention, an alkali metal hydroxide can be further contained as the component (g).

Component (g) is preferably potassium hydroxide or sodium hydroxide from the viewpoint of further improving scale accumulation inhibiting properties, detergency, tea stain adhesion inhibiting properties, blendability, and low-temperature storage stability. From the point of view, potassium hydroxide is more preferable.

When the liquid detergent composition for automatic dishwashers of the present invention contains component (g), the content of component (g) is 3.0% by mass or more, more preferably 5% by mass, from the viewpoint of further improving detergency. 0% by mass or more, more preferably 7.0% by mass or more, and from the viewpoint of alumite corrosion resistance, preferably 35% by mass or less, more preferably 32% by mass or less, even more preferably 30% by mass or less, and still more It preferably contains 25% by mass or less.

The liquid detergent composition for automatic dishwashers of the present invention contains water. As water, ion-exchanged water, distilled water, sterilized purified water, and tap water can be used.
The liquid detergent composition for automatic dishwashers of the present invention preferably contains water in an amount of preferably 8% by mass or more, more preferably 10% by mass or more, and preferably 95% by mass or less, more preferably 90% by mass or less. More preferably, it contains 85% by mass or less.

The liquid detergent composition for automatic dishwashers of the present invention comprises (a) component, (b) component, (c) component, water, optional (d) component, optional (e) component, optional (f ) component and optional (g) component can be blended and contained.
That is, the present invention includes (a) component, (b) component, (c) component, water, optional (d) component, optional (e) component, optional (f) component, and optional (g) component A liquid detergent composition for automatic dishwashers, comprising
The content of alkali metal ions in the composition is 5.0% by mass or more and 19% by mass or less, and an aqueous solution obtained by diluting the composition to 0.2% by mass with water has a pH of 10.0 or more at 25°C. It is possible to provide a liquid detergent composition for automatic dishwashers, which is 12.5 or less.

The liquid detergent composition for automatic dishwashing machines of the present invention may contain solvents, hydrotropic agents, dispersants, pH adjusters, thickeners, viscosity adjusters, perfumes, and coloring agents, as long as the objects of the present invention are not impaired. ingredients such as agents, antioxidants, preservatives, foam inhibitors, bleaches, and bleach activators (excluding those corresponding to components (a) to (g)). The remaining component of the liquid detergent composition for automatic dishwashers of the present invention is water.

The pH (JIS K 3362) at 25° C. of an aqueous solution obtained by diluting the liquid detergent composition for automatic dishwashers of the present invention to 0.2% by mass with water is 10.0 or more from the viewpoint of further improving detergency. , preferably 10.5 or more, and from the viewpoint of alumite corrosion resistance, it is 12.5 or less, preferably 12.0 or less.

[Method of washing dishes with an automatic dishwasher]
The liquid detergent composition for automatic dishwashing machines of the present invention is suitably used for washing with automatic dishwashing machines, and further automatic dishwashing machines for business use. When washing with an automatic dishwashing machine, and further with an automatic dishwashing machine for commercial use, the liquid detergent composition for automatic dishwashing machines of the present invention is used as a washing liquid mixed with water. At that time, the composition is arbitrarily transported in fixed amounts inside the automatic dishwasher by means of a feeding device to maintain a proper washing liquid concentration. The liquid detergent composition for automatic dishwashing machines of the present invention is supplied by, for example, directly inserting a dedicated tube for commercial automatic dishwashing machines into a container made of plastic or the like filled with the composition and sucking it up. be done. The cleaning liquid is then fed into the commercial dishwasher.

The present invention provides a method for washing dishes, comprising repeating the following steps 1 and 2 using a washing liquid obtained by diluting the liquid detergent composition for automatic dishwashers of the present invention with water.
Step 1: A step of washing dishes housed in a washing chamber of an automatic dishwasher for 20 seconds or more and 120 seconds or less with the washing liquid having a washing temperature of 50°C or more and 70°C or less Step 2: After step 1, 50°C or more and 80°C The following step of rinsing the tableware with water for 4 seconds or more and 10 seconds or less In the cleaning method of the present invention, the aspects described for the liquid detergent composition for automatic dishwashing machines of the present invention can be appropriately applied.
The dishes housed in the washing chamber of the automatic dishwasher are properly removed from the washing chamber after washing and rinsing are completed by carrying out steps 1 and 2, and new unwashed dishes are removed from the washing chamber. housed in a room.

From the viewpoint of economy, it is preferable that the cleaning liquid used in the cleaning method of the present invention be prepared while maintaining a constant concentration in a storage tank provided in an automatic dishwasher.

In the cleaning method of the present invention, the liquid detergent composition for automatic dishwashers of the present invention is diluted with water, from the viewpoint of economy, preferably 200 times or more by mass, more preferably 250 times or more by mass, still more preferably 300 times by mass. Dilute at a dilution ratio of at least 1,000 times by mass, more preferably 950 times by mass or less, and even more preferably 900 times by mass or less from the viewpoint of scale accumulation suppression, detergency, and tea stain adhesion suppression. A different cleaning solution is used.

In the cleaning liquid used in the cleaning method of the present invention, the concentration of the liquid detergent composition for automatic dishwashing machines of the present invention is preferably 0.00, from the viewpoint of further improving scale accumulation inhibiting properties, detergency and tea stain adhesion inhibiting properties. 01% by mass or more, more preferably 0.02% by mass or more, and preferably 0.40% by mass or less, more preferably 0.35% by mass or less.

The cleaning liquid used in the cleaning method of the present invention can contain the essential components and optional components described above in the same manner as the liquid cleaning composition for automatic dishwashing machines of the present invention, and preferred embodiments are also the same.

The content of component (a) in the cleaning solution used in the cleaning method of the present invention is preferably 0.0015% by mass or more, more preferably 0.002% by mass or more, in terms of acid conversion, from the viewpoint of scale accumulation suppression ability. More preferably 0.0025% by mass or more, preferably 0.08% by mass or less, more preferably 0.072% by mass or less, and even more preferably 0.064% by mass or less.

The content of component (b) in the cleaning solution used in the cleaning method of the present invention is preferably 0.004% by mass or less, more preferably 0.0032% by mass or less, and still more preferably 0% by mass, from the viewpoint of the ability to suppress scale accumulation. 0024% by mass or less. Also, the content of component (b) in the cleaning solution used in the cleaning method of the present invention may be 0% by mass.

The content of component (c) in the cleaning liquid used in the cleaning method of the present invention is preferably 0.004% by mass or less, more preferably 0.0032% by mass or less, and still more preferably 0% by mass, from the viewpoint of the ability to suppress scale accumulation. 0024% by mass or less. Also, the content of component (c) in the cleaning solution used in the cleaning method of the present invention may be 0% by mass.

The content of alkali metal ions in the cleaning solution used in the cleaning method of the present invention is preferably 0.0025% by mass or more, more preferably 0.003% by mass or more, and still more preferably 0.0035, from the viewpoint of improving cleaning performance. mass % or more, more preferably 0.0040 mass % or more, still more preferably 0.0045 mass % or more, and preferably 0.076 mass % or less, more preferably 0.072 mass % or less, still more preferably It is 0.068% by mass or less.

When the cleaning solution used in the cleaning method of the present invention contains component (d), the content of component (d) is preferably 0.00025% by mass or more, more preferably 0.00025% by mass or more, in terms of acid, from the viewpoint of suppressing adhesion of tea stains. is 0.00055% by mass or more, and preferably 0.04% by mass or less, more preferably 0.036% by mass or less, even more preferably 0.032% by mass, and even more preferably 0.024% by mass or less .

When the cleaning liquid used in the cleaning method of the present invention contains component (e), the content of component (e) is preferably 0.000055% by mass or more, from the viewpoint of further improving cleanability and low-foaming properties. More preferably 0.00013% by mass or more, still more preferably 0.00015% by mass or more, still more preferably 0.00018% by mass or more, still more preferably 0.00025% by mass or more, and preferably 0.02% by mass % or less, more preferably 0.018 mass % or less, still more preferably 0.016 mass % or less, still more preferably 0.012 mass % or less, still more preferably 0.008 mass % or less. However, when an anionic surfactant is contained as the component (e), the content thereof is converted to an acid value.

When the cleaning liquid used in the cleaning method of the present invention contains component (f), the content of component (f) is preferably 0.00025% by mass or more, more preferably 0, from the viewpoint of further improving cleaning performance. 0.00035% by mass or more, more preferably 0.0005% by mass or more, and preferably 0.02% by mass or less, more preferably 0.018% by mass or less, even more preferably 0.016% by mass or less, even more preferably is 0.012% by mass or less.

When the cleaning liquid used in the cleaning method of the present invention contains component (g), the content of component (g) is preferably 0.0015% by mass or more, more preferably 0, from the viewpoint of further improving cleaning performance. 0.0025% by mass or more, more preferably 0.0035% by mass or more, and from the viewpoint of alumite corrosion resistance, preferably 0.14% by mass or less, more preferably 0.128% by mass or less, still more preferably 0.12% by mass % by mass or less, and more preferably 0.1% by mass or less.

The pH (JIS K 3362) of the cleaning solution used in the cleaning method of the present invention is 10.0 or more, preferably 10.5 or more from the viewpoint of further improving cleaning performance, and 12.5 from the viewpoint of alumite corrosion resistance. Below, it is preferably 12.0 or less. The temperature for measuring the pH of the cleaning liquid is appropriately selected from the cleaning temperature range, but may be 25°C.

In step 1, the washing temperature of the washing liquid is preferably 50° C. or higher, more preferably 55° C. or higher, and preferably 70° C. or lower, more preferably 65° C. or lower.

In step 1, from the viewpoint of further improving washability, the washing time of the tableware housed in the washing chamber of the automatic dishwasher is 20 seconds or more, preferably 25 seconds or more, and 120 seconds or less, preferably 110 seconds. seconds or less, more preferably 100 seconds or less.

In step 2, the temperature of the water for rinsing the dishes is 50°C or higher, preferably 55°C or higher, more preferably 60°C or higher and 80°C or lower.

In step 2, the dishware rinse time is 4 seconds or more, preferably 5 seconds or more, and 10 seconds or less, preferably 9 seconds or less.

In the present invention, the accumulation of scale can be suppressed by continuously operating the steps 1 and 2 with a washing liquid obtained by diluting the liquid detergent composition for an automatic dishwasher of the present invention with water, but the hardness is high. water is used, in addition to the steps 1 and 2, it is preferable to provide the following step 3 for the purpose of peeling off the attached scale. That is, the present invention provides a method for washing dishes, comprising repeating steps 1 to 3 using a washing liquid obtained by diluting the liquid detergent composition for automatic dishwashers of the present invention with water.
Step 3: After continuously repeating steps 1 and 2, the temperature in the washing chamber is kept at 5° C. or higher and 40° C. or lower for 10 minutes or more and 24 hours or less. If scale is formed on the inner wall surface by repeating step 2, step 3 is performed to adjust the temperature in the cleaning chamber to the above temperature, and after leaving for a predetermined time, step 1 is performed. The crystals of the calcium salt of citric acid or gluconic acid formed by the component (a) are dissolved in the washing liquid, and the scale adhering to the inner wall surface of the automatic dishwasher can be collapsed and peeled off. . Therefore, by performing step 3 after continuously repeating steps 1 and 2, it is possible to suitably suppress scale formation and scale accumulation.

In step 3, the temperature in the cleaning chamber is 5°C or higher, preferably 10°C or higher, and 40°C or lower, preferably 35°C or lower.
In step 3, the standing time is 10 minutes or more, preferably 30 minutes or more, more preferably 1 hour or more, and 24 hours or less, preferably 15 hours or less.
It is preferable to provide step 3 after performing continuous operation of step 1 and step 2 for 1 hour or more, preferably 2 hours or more, and 12 hours or less, preferably 10 hours or less.

In automatic dishwashing machines, as well as commercial automatic dishwashing machines, the washing liquid can be circulated by a pump and used repeatedly.
When washing dishes with an automatic dishwasher or an automatic dishwasher for commercial use, the number of washings and the washing liquid ( That is, the concentration of the cleaning liquid used for cleaning decreases. When the concentration of the cleaning liquid decreases, an appropriate amount of the liquid detergent composition for automatic dishwashers is supplied to the cleaning liquid storage tank by the automatic supply device so that the concentration and pH of the cleaning liquid are maintained within appropriate ranges.

Automatic dishwashing machines, especially commercial automatic dishwashing machines, generally comprise means for containing a cleaning liquid and means for bringing the cleaning liquid contained in the containing means into contact with the dishes. The cleaning liquid containing means may be called, for example, a cleaning liquid tank, a cleaning liquid tank, or the like. Further, the means for bringing the cleaning liquid contained in the containing means into contact with the tableware can include means for conveying the cleaning liquid (such as a pipe) and means for applying the cleaning liquid to the tableware (such as a shower nozzle). Also, the means for bringing the cleaning liquid contained in the containing means into contact with the dishes can include a defined space (sometimes referred to as a washing chamber) for bringing the cleaning liquid into contact with the dishes.

The automatic supply device for the liquid detergent composition for automatic dishwashers is not limited, but is controlled by sensing the concentration of the cleaning liquid and receiving a signal. For the liquid composition of the present invention, the tube pump is driven to supply the required amount of the liquid detergent composition for automatic dishwashers of the present invention.

This automatic feeder is suitable for commercial washing machines that are washed many times a day, and the use of the automatic feeder has the advantage of significantly saving time and effort compared to manually feeding each wash. The advantage of using an automatic supply device is that it is easy to maintain the concentration of the cleaning liquid within the proper concentration range throughout the day (during cleaning).

In the cleaning method of the present invention, the liquid for automatic dishwashers of the present invention is added so that the pH of the cleaning liquid is 10.0 or higher, preferably 10.5 or higher, and 12.5 or lower, preferably 12.0 or lower. It is preferable to add the cleaning composition to the cleaning liquid continuously or intermittently to maintain the proper pH range of the cleaning liquid.

As a method for monitoring the concentration of the cleaning liquid, for example, the electric conductivity of the cleaning liquid can be used as an indicator. That is, in the cleaning method of the present invention, the liquid detergent composition for automatic dishwashers of the present invention is continuously or intermittently added to the cleaning liquid using the electrical conductivity of the cleaning liquid as an index, and the concentration of the cleaning liquid is adjusted. It is preferred to prepare and maintain the correct concentration range.

The liquid detergent compositions for automatic dishwashers shown in Tables 1 and 2 were tested for scale adhesion inhibition, scale removal, detergency, tea stain adhesion inhibition, alumite corrosion resistance, blendability, and low-temperature stability by the following methods. evaluated. In addition, the pH of the 0.2% by mass water-diluted aqueous solution at 25° C. was measured according to JIS K 3362 and shown in Tables 1 and 2.

The method for preparing the liquid detergent composition for automatic dishwashers having the composition shown in the examples is as follows.

<Method for preparing liquid detergent composition for automatic dishwasher>
The blending amount was calculated so that the total amount of each component was 3000 g. Each component was put into a 3 L beaker in the following order. Using a stirrer (Type Z-2200 manufactured by TOKYO DRIKAKIKAI) and stirring blades (3 blades: 4 cm in diameter), mixing was performed at a rotation speed of 200 (rpm/min). The temperature during preparation was adjusted in the range of 25°C to 50°C in consideration of heat generation due to neutralization.
Ion-exchanged water, components (a), and components (g) were added and mixed until uniformly dissolved. After that, components (b), (c), (d) and (f) were added and mixed until they were uniformly dissolved. Thereafter, component (e) was added and mixed until uniformly dissolved to obtain a liquid detergent composition for automatic dishwashers.

<Evaluation>
Evaluation of scale adhesion inhibition, scale removal, washability, tea stain adhesion inhibition, and alumite corrosion resistance was performed using a one-door commercial dishwasher [SANYO DR53 manufactured by SANYO Electric Co., Ltd.] as a commercial dishwasher. A washer was used. The capacity of the washing liquid tank was 38L.

Water of 2.2° dH (German hardness) was used for the preparation and rinsing of the cleaning liquid in the cleaning property, tea stain adhesion suppression property, and alumite corrosion resistance evaluation.
In each case, the hardness was adjusted by adding hard water adjusted to 10000° dH (German hardness) with calcium chloride to tap water.

[Scale adhesion suppression]
A washing liquid tank of a dishwasher was filled with a washing liquid (detergent composition concentration: 0.15% by mass) prepared by dissolving 57 g of the detergent composition shown in the table in water. One cycle (70 seconds) was defined as a washing liquid temperature of 60° C., washing time of 40 seconds, rinsing water temperature of 80° C., and rinsing time of 6 seconds, and 500 cycles (about 10 hours) were continuously operated. In this dishwasher, the concentration of each component of the cleaning liquid contained in the cleaning liquid tank is controlled to be constant during cleaning. In this dishwasher, the rinsing time of 6 seconds means that the amount of water per rinsing is 2 L or less per 2500 cm ² horizontal surface of the space where the dishes are placed and washed. The same applies to the evaluation of scale removability, detergency, and inhibition of tea stains.
After the operation was finished, it was visually determined whether the adhesion of scale to the side wall of the cleaning chamber and the side wall of the cleaning liquid tank was suppressed. Whether the adhesion of scales is suppressed is determined by the fact that the surfaces of the side wall of the cleaning chamber and the cleaning liquid tank have no discoloration or deterioration compared to before operation, and have the same gloss as the initial state, or are slightly discolored. However, a visual judgment was made based on whether or not the scale was not adhered and the surface was glossy. When scale adheres to the surface, the surface becomes dull and rough.
The contents of the above evaluation were performed by changing the hardness of the water used for preparation of the cleaning solution and rinsing, and the respective scale adhesion inhibitory properties were determined. In Tables 1 and 2, the upper limit hardness at which scale adhesion is suppressed is defined as the scale adhesion suppressible hardness (° dH). It shows that the higher the scale-adhesion-inhibiting hardness, the higher the scale-adhesion inhibitory effect.

[Scale peelability]
For scale release evaluation, 10° dH (German hardness) water was used for cleaning solution preparation and rinsing. When the scale adhesion inhibitory property is evaluated using water having this hardness, the water has a hardness that causes scale adhesion to be confirmed in both the examples and the comparative examples. Using water of the above hardness, the scale adhesion suppression property was evaluated (continuous operation of 500 cycles), and after confirming the adhesion of scale, the door of the dishwasher was closed and sealed, and the dishwasher was operated. The temperature in the washing chamber was kept at 25° C. for 12 hours. Thereafter, 20 cycles (about 25 minutes) of continuous operation were performed with one cycle (70 seconds) consisting of a cleaning liquid temperature of 60° C., a cleaning time of 40 seconds, a rinsing temperature of 80° C., and a rinsing time of 6 seconds. After the operation was completed, the degree of peeling of scale on the inner wall surfaces of the cleaning chamber and the cleaning liquid tank was visually determined according to the following criteria. The results are shown in the table.
○: Compared to before continuous operation of 500 cycles, no discoloration or deterioration was observed, and the same gloss as the initial state, or a slight discoloration, but the scale was peeled off and the gloss was maintained.
x: Compared to before 500 cycles of continuous operation, the gloss is lost, the surface is rough, and the scale is not peeled off.

[Washability]
A magnetic dish with an inner diameter of 200 mm and a peripheral wall of 30 mm height was weighed. 2 g of egg yolk was uniformly applied as a model stain to a magnetic dish over a radius of 7 cm from the center. After that, it was dried at 60° C. for 30 minutes, and two magnetic plates used for evaluation were prepared for one sample.
They are set in the washing chamber of a dishwasher, and the washing liquid tank (38 L) of the washing machine is filled with a washing liquid having a detergent composition concentration of 0.15% by mass prepared from the detergent composition shown in the table (however, Germany diluted with water with a hardness of 2.2° dH). Then, washing was performed under the conditions of a washing liquid temperature of 50° C., a washing time of 40 seconds, a rinsing water temperature of 80° C., and a rinsing time of 10 seconds. In this dishwasher, the concentration of the cleaning liquid contained in the cleaning liquid tank is controlled to be constant during cleaning. After the washed magnetic dish was taken out, it was dried in a room adjusted to 25°C ± 5°C, and then weighed. The weight of the magnetic dish after washing minus the weight of the dish itself (remaining soil weight), and the weight of the magnetic dish itself dried after applying the egg yolk stain minus the weight of the dish itself (coated soil weight) are calculated using the following formula: [100-[(residual stain weight)/(coated stain weight)]×100] was used as the heat-denatured egg yolk cleaning rate (%). The table shows the cleaning rate values and evaluation results according to the following criteria. 3 or more is preferable according to the following criteria.
Detergency Evaluation Criteria 5: Detergency 90% or more 4: Detergency 80% or more and less than 90% 3: Detergency 70% or more and less than 80% 2: Detergency 60% or more and less than 70% 1: Detergency 50% or more 60 %less than

[Tea stain adhesion suppression]
The prepared liquid detergent composition was put into a dishwasher, washing liquid temperature 50 ° C., detergent composition concentration in washing liquid 0.15 mass%, washing time 40 seconds, rinsing water temperature 80 ° C., rinsing time 10 seconds, And the washing machine was continuously operated 10 times under the condition that the amount of water per rinsing was 2 L. Adjustments were made so that the concentration of the detergent composition in the cleaning liquid did not fluctuate during the test.

(Method for evaluating tea stain adhesion inhibitory effect)
Boiled black oolong tea (2 black oolong tea bags are added to 1.8L of boiling water, boiled for 10 minutes, and cooled to room temperature) are poured into 4 melamine cups (approximately 150cc capacity). I put it in until the 8th minute. After standing for 60 seconds, the black oolong tea was discarded and left for 10 minutes. The melamine cup after standing was set in the washing chamber of the dishwasher and washed under the washing conditions described above. This was repeated 10 times (addition, disposal and washing of black oolong tea were performed 10 times). After that, the appearance was visually observed, and the tea stain adhesion inhibitory effect was determined according to the following criteria. The results are shown in the table. A score of 4 or more is preferable according to the following evaluation criteria. It should be noted that no difference in the state of the four cups could be observed in washing with individual detergent compositions. In addition, the content of component (a) in the cleaning liquid was the same as the scale accumulation inhibitory property in terms of acid.

Evaluation Criteria for Suppressing Effect of Adhesion of Tea Stains 5: Tea stains are not adhered to any of the four melamine cups.
4: Slight tea astringency adheres to all four melamine cups. (Slight adhesion can be confirmed than evaluation 5)
3: Slight adhesion of brown spots is observed on all four melamine cups.
2: Adhesion of tea stains is observed on all four melamine cups. (It can be confirmed that there is more adhesion than evaluation 3 and less adhesion than evaluation 1)
1: Adhesion of strong tea astringency is observed on all four melamine cups.

[Alumite corrosion resistance]
Into a 100 ml high-density polyethylene bottle, 30 mL of a 0.2% by mass water-diluted cleaning solution obtained by diluting the prepared liquid cleaning composition 500 times by mass with water having a German hardness of 2.2°dH was put. An A1050P test piece (manufactured by Nippon Test Panel Co., Ltd.) subjected to sulfuric acid alumite processing was immersed therein and held at a liquid temperature of 60° C. for 1 hour. After holding, the test piece was taken out, rinsed with deionized water at 25°C ± 5°C for 30 seconds, water droplets were removed with air, and dried at 25°C ± 5°C. After drying, the appearance of the obtained test plate was visually observed and evaluated according to the following criteria. The results are shown in the table. A score of 4 or more is preferable according to the following evaluation criteria.
Evaluation criteria for corrosion resistance of alumite 5: Maintains the original gloss of the test piece.
4: Part of the test piece is whitened.
3: Most of the test piece is whitened.
2: In addition to whitening of the test piece, some black rust occurred.
1: Black rust occurred from most of the test piece.

[Compatibility]
When the liquid detergent composition was prepared by the above method, the time from immediately after mixing the component (e) as the final raw material to uniform dissolution was checked and evaluated according to the following criteria. The results are shown in the table. A score of 4 or more is preferable according to the following evaluation criteria.
Evaluation Criteria for Mixability 5: Dissolved in less than 2 minutes after final raw material mixing.
4: Dissolved in 2 minutes or more and less than 5 minutes after final raw material mixing.
3: Dissolved in 5 to less than 10 minutes after final raw material mixing.
2: Dissolved in 10 to less than 20 minutes after final raw material mixing.
1: Dissolved in 20 minutes or more after final raw material mixing.

[Low temperature stability]
90 ml of the prepared liquid detergent composition was placed in a 100 ml polypropylene container, sealed and stored at −5° C. for 10 days. The results are shown in the table. 3 or more is preferable in the following evaluation criteria.
Low-temperature stability evaluation criteria 5: Uniformly transparent (no turbidity observed).
4: Turbidity is observed very slightly.
3: Slight turbidity is observed.
2: Turbidity is recognized.
1: Turbidity was observed and two-layer separation occurred.

When the liquid detergent composition for automatic tableware of the present invention is used as a cleaning liquid, adhesion of scale can be suppressed even when water at 7.5°dH is used. Furthermore, by using water exceeding 7.5° dH, even if scale adheres, the scale can be removed by using the automatic dishwashing liquid detergent composition of the present invention as a cleaning liquid. Scale accumulation can be suppressed even under high hardness conditions exceeding 5°dH. In the evaluation of scale releasability, 10° dH water was used, but if the automatic dishwashing liquid detergent composition of the present invention is used, scale can be removed even when 15° dH water is used. It is possible to suppress the accumulation of scale.

[Ingredients]
In the table, the components used as raw materials for the liquid detergent compositions are as follows.
<(a) component>
・Citric acid: “Food additive citric acid (anhydrous)” [manufactured by Iwata Chemical Co., Ltd.], molecular weight 192
・Gluconic acid: reagent (50% gluconic acid aqueous solution), molecular weight 196
<(a′) component (comparative component of (a) component)>
・ Malic acid: reagent (DL-malic acid) (special grade), molecular weight 134
<(b) component>
· Potassium orthosilicate: manufactured by Koei Chemical Industry Co., Ltd., content: 36% or more as SiO ₂ /K ₂ O [from Koei Chemical Industry Co., Ltd. SDS]
· No. 1 sodium silicate: manufactured by Osaka Soda Co., Ltd., SiO ₂ /Na ₂ O molar ratio = 2.0 to 2.3 [from Osaka Soda Co., Ltd. SDS]
<(c) component>
・Potassium carbonate: reagent (special grade)
<(d) component>
- MGDA: trisodium methylglycine diacetate, "Trilon M Liquid" [manufactured by BASF], pKca 6.3 (25 ° C., pH 10)
EDTA: Sodium ethylenediaminetetraacetate, "Cherest 400" [manufactured by Cherest Co., Ltd.], pKca 12.2 (25 ° C., pH 10)
<(e) component>
・ Caprylic acid: “Lunac 8-98” [manufactured by Kao Corporation]
- Potassium alkenyl succinate: "Latemul DSK" [manufactured by Kao Corporation]
- Nonionic surfactant (1): a nonionic surfactant represented by the general formula (e-3), weight average molecular weight 3,100, propylene oxide/ethylene oxide ratio = 80/20, trade name "Pluronic RPE2520" ( manufactured by BASF Japan)
<(f) component>
- Sodium polyacrylate: "Sokalan PA25CL FR" [manufactured by BASF Japan, sodium salt of acrylic acid homopolymer, weight average molecular weight 4,000]
<(g) component>
・Potassium hydroxide: reagent (special grade)

Claims (7)

(a) one or more selected from citric acid and its alkali metal salts in terms of acid, 5.0 % by mass or more and 20% by mass or less with respect to the total amount of the composition, optionally (b) a water-soluble silicate, Less than 1.0% by weight of the total composition, optionally (c) an alkali metal carbonate, less than 1.0% by weight of the total composition, and (g) potassium hydroxide, of the total composition 5.0 % by mass or more and 25% by mass or less, and water,
The content of alkali metal ions in the composition is 8.0% by mass or more and 19% by mass or less, and an aqueous solution obtained by diluting the composition to 0.2% by mass with water has a pH of 10.0 or more at 25°C. A liquid detergent composition for automatic dishwashers, which is 12.5 or less. 2. The automated system according to claim 1, further comprising (d) an aminocarboxylic acid-type sequestering agent having a pKca of 5 or more and 14 or less at 25° C. and pH 10 in an acid conversion of 10% by mass or less relative to the total amount of the composition. A liquid detergent composition for dishwashers. 3. The liquid detergent composition for automatic dishwashers according to claim 1, further comprising (e) a surfactant in an amount of 0.1% by mass or more and 5.0% by mass or less based on the total amount of the composition. The automatic dishwasher according to any one of claims 1 to 3, further comprising (f) a carboxylic acid-based polymer in an amount of 0.5% by mass or more and 5.0% by mass or less based on the total amount of the composition. Liquid detergent composition. A method for washing dishes, comprising repeating the following steps 1 and 2 using a washing liquid obtained by diluting the liquid detergent composition for an automatic dishwasher according to any one of claims 1 to 4 with water.
Step 1: A step of washing dishes housed in a washing chamber of an automatic dishwasher for 20 seconds or more and 120 seconds or less with the washing liquid having a washing temperature of 50°C or more and 70°C or less Step 2: After step 1, 50°C or more and 80°C The process of rinsing the tableware with the following water for 4 seconds or more and 10 seconds or less 6. The method for washing tableware according to claim 5, further comprising the following step 3 and repeating steps 1 to 3.
Step 3: After continuously repeating steps 1 and 2, the temperature in the washing chamber is kept at 5°C or higher and 40°C or lower for 10 minutes or longer and 24 hours or shorter. The method for washing tableware according to claim 5 or 6, wherein the washing liquid has a pH of 10.0 or more and 12.5 or less at 25°C.