Liquid detergent composition for automatic dishwasher, and method of washing tableware by automatic dishwasher

Abstract

To discover a composition (constituent) useful for developing a formulation of a liquid detergent composition for an automatic dishwasher containing sodium hydroxide and / or potassium hydroxide, the formulation having sufficiently high conductivity and high storage stability even when diluted at a high dilution ratio.SOLUTION: A liquid detergent composition for an automatic dishwasher includes: (A) sodium hydroxide and / or potassium hydroxide; and (B) sodium chloride and / or potassium chloride, where the total content of (A) sodium hydroxide and / or potassium hydroxide is 4 mass% or more and each content of sodium hydroxide and potassium hydroxide is 5 mass% or less, and the total content of (B) sodium chloride and / or potassium chloride is 5 mass% or more.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a novel liquid detergent composition for automatic dishwashing machines and a method for washing dishes in an automatic dishwashing machine using the same. [Background technology]

[0002] In an automatic dishwasher, a diluted detergent solution obtained by diluting a special detergent is sprayed onto the surface of the dirty tableware to be washed with a high-pressure water flow to remove dirt from the tableware. In this case, in commercial automatic dishwashers, a liquid detergent for automatic dishwashers containing an alkaline agent is usually used to effectively remove dirt from the tableware by spray washing. This is because the alkaline agent has a decomposition effect and a solubilization effect on protein stains, etc., which enables speedy and efficient washing of the tableware. For example, Patent Document 1 discloses a liquid detergent composition for automatic dishwashers containing an alkaline agent as the main component, which contains an alkaline agent, an aminocarboxylic acid type chelating agent, and an organic phosphoric acid or a salt thereof.

[0003] In recent years, there has been an increasing need for compact (concentrated) liquid detergents that do not take up space during storage in commercial automatic dishwashers, and this has led to a demand for the development of formulations for liquid detergents for automatic dishwashers that can be diluted at higher rates for use. On the other hand, it is also necessary to maintain high storage stability (including low-temperature storage stability) of liquid detergents so that they can be easily handled during storage.

[0004] Incidentally, alkaline agents contained in liquid detergents for automatic dishwashers include alkali metal hydroxides such as sodium hydroxide, and carbonates such as sodium carbonate, among which sodium hydroxide and potassium hydroxide are generally considered for incorporation first. On the other hand, if the detergent contains more than 5% by mass of either sodium hydroxide or potassium hydroxide, the detergent becomes a hazardous substance and is subject to handling restrictions, so when sodium hydroxide and potassium hydroxide are incorporated, it is desirable to keep their total content at 10% by mass or less (i.e., each content is 5% by mass or less). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2020-164729 A Summary of the Invention [Problem to be solved by the invention]

[0006] The present inventors conducted research to develop a new formulation for a liquid detergent for automatic dishwashers that contains sodium hydroxide and / or potassium hydroxide as an alkaline agent, is compact (concentrated type), and has excellent storage stability. As a result, it was confirmed that even if the total content of sodium hydroxide and potassium hydroxide is 10% by mass or less (i.e., each content is 5% by mass or less), as long as it contains a certain amount or more (for example, a total content of 4% by mass or more) of sodium hydroxide and / or potassium hydroxide, the decomposition action and solubilization action as an alkaline agent are ensured even by high dilution (for example, 2000-fold dilution). On the other hand, in an actual washing test using an automatic dishwasher, the present inventors noticed that when used at such a high dilution, the amount of detergent put into the automatic dishwasher was not stable depending on the items to be washed. Then, the present inventors conducted further research on this problem and found that this was caused by insufficient conductivity of the diluted detergent solution during washing.

[0007] That is, currently, many commercial automatic dishwashers are equipped with a detergent supply device (automatic dosing mechanism) for the purpose of labor saving. In this case, the amount of detergent dosing is generally controlled to a predetermined detergent concentration using the conductivity of the diluted solution as an index. For this reason, when the conductivity of the diluted solution is low, the conductivity of the diluted solution is affected depending on the type and amount of dirt attached to the object to be washed. On the other hand, sodium hydroxide and potassium hydroxide have a role of imparting conductivity to the diluted detergent solution in addition to the cleaning action as the above-mentioned alkaline agent, but when the total content is 10 mass% or less, sufficient conductivity may not be obtained due to high dilution, and therefore it has become impossible to stably and appropriately control the amount of detergent dosing. For these reasons, in the development of a formulation for a compact (concentrated type) liquid detergent, it was considered effective to blend a component that can impart a sufficiently high conductivity during dilution so that it is not affected by dirt derived from the object to be washed, taking into consideration the viewpoint of stably and appropriately performing automatic dosing of the detergent during use. It was also considered necessary that the component that imparts such electrical conductivity has a small effect on the compounding stability of the liquid detergent even when it is added.

[0008] As described above, the present inventors have found that when attempting to develop a new formulation for a liquid detergent for automatic dishwashers that contains sodium hydroxide and / or potassium hydroxide as an alkaline agent and is compact (concentrated type) and has excellent storage stability, the electrical conductivity of the diluted solution may be insufficient during use. The present invention has been made based on such a newly discovered viewpoint. Therefore, the object of the present invention is to find a formulation (compounds) that is useful for developing a formulation for a liquid detergent for automatic dishwashers that contains sodium hydroxide and / or potassium hydroxide and has sufficiently high electrical conductivity even when diluted at a high ratio and also has high storage stability. [Means for solving the problem]

[0009] The present inventors have conducted extensive research to find a combination (compounds) useful for developing a liquid detergent for automatic dishwashers that contains sodium hydroxide and / or potassium hydroxide and has sufficiently high electrical conductivity even when diluted at a high ratio and also has high storage stability, and have unexpectedly found that sodium chloride and / or potassium chloride are suitable for blending in the liquid detergent for automatic dishwashers, thus completing the present invention. The gist of the present invention is as follows.

[0010] [1] A liquid detergent composition for automatic dishwashers, comprising (A) sodium hydroxide and / or potassium hydroxide and (B) sodium chloride and / or potassium chloride, in which the total content of (A) sodium hydroxide and / or potassium hydroxide is 4 mass% or more and the contents of each of sodium hydroxide and potassium hydroxide are 5 mass% or less, and the total content of (B) sodium chloride and / or potassium chloride is 5 mass% or more. [2] The liquid detergent composition for automatic dishwashers according to [1], having a pH of 11.0 or more. [3] The liquid detergent composition for automatic dishwashers according to [1] or [2], further comprising a polymer dispersant and / or a chelating agent. [4] A method for washing tableware in an automatic dishwasher, comprising washing tableware with the liquid detergent composition for automatic dishwashers according to any one of [1] to [3].

[0011] In addition, any two or more of the configurations [1] to [4] above can be selected and combined. Effect of the Invention

[0012] According to the present invention, by blending sodium chloride and / or potassium chloride, it is possible to impart high conductivity to a cleaning agent containing sodium hydroxide and / or potassium hydroxide without significantly affecting its storage stability. Therefore, it is possible to easily design a liquid cleaning agent for automatic dishwashers containing sodium hydroxide and / or potassium hydroxide that has sufficiently high conductivity even when diluted at a high ratio and also has high storage stability when concentrated. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The present invention will now be described in detail. In addition, the terms used in this specification are to be interpreted as having the meanings usually used in the technical field unless otherwise specified.

[0014] <Liquid detergent composition for automatic dishwashing machines> The liquid detergent composition for automatic dishwashers of the present invention (hereinafter sometimes simply referred to as the liquid detergent composition) contains (A) sodium hydroxide and / or potassium hydroxide and (B) sodium chloride and / or potassium chloride, in which the total content of (A) sodium hydroxide and / or potassium hydroxide is 4 mass% or more and the contents of each of sodium hydroxide and potassium hydroxide are 5 mass% or less, and the total content of (B) sodium chloride and / or potassium chloride is 5 mass% or more.

[0015] In the liquid detergent composition for automatic dishwashers of the present invention, the content of (A) sodium hydroxide and / or potassium hydroxide is limited to a low content so as to facilitate handling, while (B) sodium chloride and / or potassium chloride is contained in a total amount of 5 mass% or more. By blending sodium chloride and / or potassium chloride in this manner, it is possible to easily develop a formulation for a liquid detergent composition for automatic dishwashers that can obtain a sufficiently high conductivity even when diluted at a high ratio and can maintain high storage stability when concentrated.

[0016] [(A) Sodium hydroxide and / or potassium hydroxide] The liquid detergent composition of the present invention contains at least one of sodium hydroxide and potassium hydroxide as component (A), and the total content of component (A) is adjusted to 4% by mass or more. In the liquid detergent composition of the present invention, sodium hydroxide and / or potassium hydroxide (A) is contained in a total of 4% by mass or more, which is a concentration that can exhibit sufficient decomposition and solubilization action as an alkaline agent even when diluted at a high ratio (for example, 2000 times). Thus, the total content of sodium hydroxide and / or potassium hydroxide (A) in the liquid detergent composition of the present invention can be appropriately blended without any particular limitation as long as it is 4% by mass or more as described above, and the lower limit of the total content is preferably 5% by mass or more, more preferably 6% by mass or more, and even more preferably 7% by mass or more.

[0017] On the other hand, in the liquid detergent composition of the present invention, the respective contents of sodium hydroxide and potassium hydroxide are limited to 5% by mass or less. The reason for limiting the contents of sodium hydroxide and potassium hydroxide in this way is to avoid the fact that reagents containing more than 5% by mass of either are treated as hazardous substances under the Poisonous and Deleterious Substances Control Law, and to make handling easier. Therefore, the upper limit of the total content of (A) sodium hydroxide and / or potassium hydroxide in the liquid detergent composition of the present invention is 10% by mass or less.

[0018] [(B) Sodium chloride and / or potassium chloride] The liquid detergent composition of the present invention contains at least one of sodium chloride and potassium chloride as component (B), and the total content of component (B) is adjusted to 5 mass% or more. In order to impart high conductivity to the liquid detergent composition of the present invention, a total of 5 mass% or more of (B) sodium chloride and / or potassium chloride is contained. As described later, in a liquid detergent composition containing (A) sodium hydroxide and / or potassium hydroxide, the blending of (B) sodium chloride and / or potassium chloride is stable, and the storage stability (including low-temperature storage stability) is also high.

[0019] The total content of (B) sodium chloride and / or potassium chloride in the liquid detergent composition of the present invention is 5% by mass or more as described above, and can be blended in an appropriate amount without any particular limitation as long as the effects of the present invention are achieved. The lower limit of the total content of (B) sodium chloride and / or potassium chloride is, for example, preferably 7% by mass or more, more preferably 10% by mass or more, from the viewpoint of electrical conductivity. The upper limit of the total content of (B) sodium chloride and / or potassium chloride is preferably 30% by mass or less, more preferably 25% by mass or less, and even more preferably 20% by mass or less, from the viewpoint of storage stability. The numerical range of the total content of (B) sodium chloride and / or potassium chloride is preferably 5% by mass or more and 30% by mass or less, more preferably 5% by mass or more and 25% by mass or less, and even more preferably 5% by mass or more and 20% by mass or less.

[0020] [Polymer dispersant and / or chelating agent] The liquid detergent composition of the present invention preferably further contains a polymeric dispersant and / or a chelating agent in addition to the above components.

[0021] (Polymer dispersant) In the liquid detergent composition of the present invention, the polymer dispersant can be contained from the viewpoint of, for example, preventing scale generation and preventing scale adhesion. The polymer dispersant can be any polymer dispersant known in the art, without any particular limitation. Specifically, for example, polyacrylic acid, polymethacrylic acid, polymaleic acid, polyitaconic acid, acrylic acid / methacrylic acid copolymer, acrylic acid / maleic acid copolymer, acrylic acid / sulfonic acid monomer copolymer, olefin / maleic acid copolymer, maleic anhydride / styrene copolymer, maleic anhydride / ethylene copolymer, maleic anhydride / vinyl acetate copolymer, maleic anhydride / acrylic acid ester copolymer, sugar / acrylic acid copolymer, lignin sulfonic acid, polyaspartic acid, polyethyleneimine, alkoxylated polyethyleneimine, and salts thereof can be used. Among them, polyacrylic acid, acrylic acid / sulfonic acid monomer copolymer, and salts thereof can be preferably used, and polyacrylic acid and its salts are particularly preferred. The average molecular weight of these may be within the range generally used in the art, for example, 1000 to 100000. In the liquid detergent composition of the present invention, the polymer dispersant may be used alone or in combination of two or more kinds.

[0022] The content of the polymer dispersant in the liquid detergent composition of the present invention is not particularly limited as long as it is within the range in which the effects of the present invention are achieved, and an appropriate amount can be blended. The lower limit of the content of the polymer dispersant is preferably 0.1 mass% or more, more preferably 0.5 mass% or more, even more preferably 1 mass% or more, and particularly preferably 1.5 mass% or more, from the viewpoint of preventing scale adhesion. The upper limit of the content of the polymer dispersant is preferably 25 mass% or less, more preferably 20 mass% or less, even more preferably 15 mass% or less, and particularly preferably 10 mass% or less, from the viewpoint of blend stability of the liquid detergent composition. The numerical range of the content of the polymer dispersant is preferably 0.1 mass% or more and 25 mass% or less, more preferably 0.5 mass% or more and 20 mass% or less, even more preferably 1 mass% or more and 15 mass% or less, and particularly preferably 1.5 mass% or more and 10 mass% or less.

[0023] (chelating agent) In the liquid detergent composition of the present invention, a chelating agent can be contained from the viewpoint of, for example, improving the detergency and preventing the generation of scale. Any chelating agent known in the art can be used without any particular limitation. Specifically, for example, ethylenediaminetetraacetic acid (EDTA), hydroxyethylethylenediaminetriacetic acid (HEDTA), nitrilotriacetic acid (NTA), triethylenetetraaminehexaacetic acid (TTHA), 1,3-propanediaminetetraacetic acid (PDTA), 1,3-diamino-2-hydroxypropanetetraacetic acid (DPTA-OH), dihydroxyethylglycine (DHEG), glycol ether diaminetetraacetic acid (GEDTA), 3-hydroxy-2,2-iminodisuccinic acid, (HIDS), alanine diacetic acid, diethylenetriaminepentaacetic acid (DTPA), 2-phosphonobutane-1,2,4-tricarboxylic acid, ethylenediaminedisuccinic acid (EDDS), hydroxyethyliminodiacetic acid (HIDA), glutamic acid diacetic acid (GLDA), methylglycine diacetic acid (MGDA), aspartic acid diacetic acid (ASDA), tripolyphosphoric acid, citric acid, malic acid, gluconic acid, diethylglutaric acid, phytic acid and salts thereof can be used. Among them, ethylenediaminetetraacetic acid (EDTA), methylglycine diacetic acid (MGDA) and salts thereof can be preferably used, and methylglycine diacetic acid (MGDA) and salts thereof are particularly preferred. In the liquid detergent composition of the present invention, the chelating agent may be used alone or in combination of multiple types.

[0024] The content of the chelating agent in the liquid detergent composition of the present invention is not particularly limited as long as it is within the range in which the effects of the present invention are achieved, and an appropriate amount can be blended. The lower limit of the content of the chelating agent is preferably 2% by mass or more, more preferably 4% by mass or more, and even more preferably 6% by mass or more, from the viewpoint of detergency. The upper limit of the content of the chelating agent is preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less, from the viewpoint of blending stability of the liquid detergent composition. The numerical range of the content of the chelating agent is preferably 2% by mass or more and 20% by mass or less, more preferably 4% by mass or more and 15% by mass or less, and even more preferably 6% by mass or more and 10% by mass or less.

[0025] The total content of the polymer dispersant and / or chelating agent in the liquid detergent composition of the present invention is not particularly limited, and can be appropriately blended as long as the effects of the present invention are achieved. The lower limit is preferably 2% by mass or more, more preferably 4.5% by mass or more, and even more preferably 7% by mass or more. The upper limit is preferably 45% by mass or less, more preferably 35% by mass or less, and even more preferably 25% by mass or less. The numerical range of the total content is preferably 2% by mass or more and 45% by mass or less, more preferably 4.5% by mass or more and 35% by mass or less, and even more preferably 7% by mass or more and 25% by mass or less.

[0026] [Other ingredients] In addition to the above-mentioned components, the liquid detergent composition of the present invention may contain surfactants, enzymes, dyes, bactericides, water-soluble solvents, defoamers, bleaching agents, bleach activators, antioxidants, fragrances, metal corrosion inhibitors, preservatives, etc., as necessary. In addition, the liquid detergent composition of the present invention may contain any alkaline agent other than sodium hydroxide and potassium hydroxide, so long as the effects of the present invention are achieved. Since the present invention is a liquid detergent composition for automatic dishwashers that contains an alkaline agent, it is preferable that the composition does not contain, for example, enzymes, and more specifically, it is preferable that the composition does not contain, for example, amylase, protease, and cellulase, and it is particularly preferable that the composition does not contain amylase.

[0027] In the liquid detergent composition of the present invention, the solvent is water. The water contained in the liquid detergent composition of the present invention is not particularly limited, and examples thereof include tap water, ion-exchanged water, purified water, distilled water, pure water, soft water, hard water, etc.

[0028] The liquid detergent composition of the present invention can be produced by mixing the above-mentioned components in a conventional manner.

[0029] [pH] The pH of the liquid detergent composition of the present invention is not particularly limited, but is, for example, 11.0 or more, preferably 11.5 or more, more preferably 12.0 or more, even more preferably 12.5 or more, and particularly preferably 13.0 or more. Such a high pH is preferable from the viewpoint of detergency. Since the liquid detergent composition of the present invention is an aqueous solution, the upper limit of its pH is 14.0.

[0030] [Automatic dishwasher applications] The liquid detergent composition of the present invention is used in an automatic dishwashing machine. Typically, the liquid detergent composition of the present invention is diluted to a predetermined concentration through a detergent supplying device integrally built into or attached to various automatic dishwashing machines, and the diluted detergent solution is used to wash objects to be washed in the automatic dishwashing machine. At this time, the detergent supplying device automatically supplies the detergent so as to maintain the detergent concentration of the diluted solution at a predetermined concentration, using the conductivity of the diluted solution as an index. The detergent composition of the present invention can be used in any automatic dishwashing machine without any particular limitation, and can be suitably used in automatic dishwashing machines having a detergent supplying device, for example, in various automatic dishwashing machines for home or commercial use that are generally available, such as conveyor-type automatic dishwashing machines such as rack conveyor type and flight conveyor type.

[0031] The above-mentioned items to be washed are not particularly limited as long as they can be washed by an automatic dishwasher, and examples thereof include tableware, cooking utensils, trays, bottles, cans, etc.

[0032] The liquid detergent composition of the present invention can also be used for aeration cleaning, immersion cleaning, vacuum boiling cleaning, and the like.

[0033] <How to wash dishes using an automatic dishwasher> The method for washing dishes using an automatic dishwasher of the present invention (hereinafter, sometimes simply referred to as the washing method) is characterized by using the liquid detergent composition for automatic dishwashers of the present invention, and other steps, conditions, etc. are not limited. The above-mentioned explanation of the liquid detergent composition for automatic dishwashers of the present invention can be used to explain this washing method, and the explanation of this washing method can also be used to explain the liquid detergent composition for automatic dishwashers of the present invention.

[0034] The cleaning method of the present invention includes, for example, a spray cleaning step of spraying a diluted solution of the liquid detergent composition of the present invention onto tableware contained in an automatic dishwashing machine cabinet.

[0035] In the cleaning method of the present invention, the liquid detergent composition of the present invention is usually diluted with water (for example, tap water) and used as a diluted detergent solution.

[0036] In the cleaning method of the present invention, the dilution ratio of the liquid detergent composition at the time of use is, for example, 2 to 100,000 times, preferably 100 to 10,000 times, more preferably 500 to 3,000 times, and further preferably 1,000 to 2,500 times. The concentration of the liquid detergent composition of the present invention in the diluted detergent solution is, for example, 0.001 mass% or more and 50 mass% or less, preferably 0.01 mass% or more and 1 mass% or less, more preferably 0.03 mass% or more and 0.2 mass% or less, and further preferably 0.04 mass% or more and 0.1 mass% or less.

[0037] In the cleaning method of the present invention, the electrical conductivity of the diluted cleaning solution when the liquid cleaning composition is diluted during use is not particularly limited as long as it is high enough not to be significantly affected by dirt attached to the object to be cleaned, and an example is 200 μS / cm to 4000 μS / cm. Also, 250 μS / cm to 3000 μS / cm is more preferable, and 300 μS / cm to 2500 μS / cm is particularly preferable. The electrical conductivity here is measured in the same manner as in the method described in the "Conductivity Test" section below, and is the difference in electrical conductivity from the dilution water.

[0038] In the cleaning method of the present invention, the temperature during jet cleaning can be appropriately set, for example, to 1 to 100°C.

[0039] In the cleaning method of the present invention, the cleaning time by jet cleaning can be appropriately set, and is, for example, from 1 second to 24 hours.

[0040] The cleaning method of the present invention includes, for example, a detergent dilution step of diluting a liquid detergent composition. Here, for example, the conductivity (electrical conductivity) of the diluted solution is used as an index of the concentration of the liquid detergent composition in the diluted solution, and the detergent is diluted so that the concentration of the detergent falls within a predetermined range based on this index. Note that this detergent dilution step also includes, for example, mixing additional detergent into an existing diluted solution and adjusting the concentration of the detergent in the diluted solution to fall within a predetermined range. EXAMPLES

[0041] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0042] Liquid detergent compositions having the compositions shown in Tables 1 to 5 were prepared and the following tests were carried out. The components used in the formulation are shown below. In the following, "%" stands for mass % unless otherwise specified. The values ​​in parentheses in Tables 1 to 5 are values ​​converted into pure contents.

[0043] [Ingredients] <Alkaline agent> Sodium hydroxide: Tosoh Corporation 48% potassium hydroxide solution: Toagosei Co., Ltd.

[0044] <Chelating agent> 40% trisodium methylglycine diacetate solution: Trade name "Trilon M biobased liquid", manufactured by BASF

[0045] <Polymer dispersant> 45% sodium polyacrylate solution: Product name "Sokalan CP10", manufactured by BASF

[0046] <Salt ingredients> Sodium chloride: Fujifilm Wako Pure Chemical Industries, Ltd. Potassium chloride: Fujifilm Wako Pure Chemical Industries, Ltd. Ammonium chloride: Fujifilm Wako Pure Chemical Industries, Ltd. Sodium metasilicate 9-hydrate (purity 39%): Nagai Pharmaceutical Co., Ltd. No. 1 potassium silicate (81% pure): Fuji Chemical Co., Ltd. Sodium carbonate: Fujifilm Wako Pure Chemical Industries, Ltd. Potassium carbonate: Fujifilm Wako Pure Chemical Industries, Ltd. Sodium sulfate: Fujifilm Wako Pure Chemical Industries, Ltd. Sodium citrate: Fujifilm Wako Pure Chemical Industries, Ltd.

[0047] [pH] Each liquid detergent composition was prepared as described above, and then the liquid temperature was adjusted to 25° C. The pH of each liquid detergent composition was measured using a LAQUA pH METER F-71 (manufactured by HORIBA Corporation).

[0048] [Compound stability test] Each liquid detergent composition was prepared as described above, and then the liquid temperature was adjusted to 25° C. The appearance was visually observed and the blend stability was evaluated. The evaluation criteria were as follows. ○: Transparent. ×: At least one of white turbidity, separation, precipitation, and sedimentation occurs.

[0049] [Low temperature storage stability test] Each liquid detergent composition was prepared as described above and then stored at -5°C for 24 hours. The appearance was then visually observed and the low-temperature storage stability was evaluated. The evaluation criteria were as follows. ○: Transparent. ×: At least one of white turbidity, separation, precipitation, and sedimentation occurs.

[0050] [Seed crystal test] After preparing each liquid detergent composition as described above, 1 g (solid) of each salt component (for example, sodium chloride salt if sodium chloride is added, potassium chloride salt if potassium chloride is added; however, sodium metasilicate nonahydrate for potassium silicate No. 1) was added to 100 g of liquid detergent composition and stored at -5°C for one day. The appearance was then visually observed to evaluate whether salt crystals derived from the liquid detergent composition had formed. The evaluation criteria are as follows: ◯: No crystal formation was observed. ×: Crystallization was observed.

[0051] [Conductivity test] The electrical conductivity of each liquid detergent composition when diluted 2000 times was evaluated by comparing it with the electrical conductivity of tap water. Specifically, the electrical conductivity of tap water at 25°C was measured first. Next, each liquid detergent composition was diluted 2000 times with tap water (0.05% detergent dilution), and the electrical conductivity of the diluted solution at 25°C was measured. The difference between the electrical conductivity of the 0.05% detergent dilution and the electrical conductivity of tap water was calculated, and evaluated according to the following evaluation criteria. The electrical conductivity meter used was CyberScan CON400 (manufactured by AS ONE Corporation). ○: Conductivity difference is 300 μS / cm or more ×: Conductivity difference is less than 300 μS / cm

[0052] [Table 1]

[0053] [Table 2]

[0054] [Table 3]

[0055] [Table 4]

[0056] [Table 5]

[0057] The results of the blending stability test, low-temperature storage stability test, seed crystal test, and electrical conductivity test are shown in Tables 1 to 5. As shown in Tables 1 to 5, Examples 1 to 6 are liquid detergent compositions containing a total of slightly less than 10 mass% sodium hydroxide and potassium hydroxide, but containing 5, 7, or 10 mass% sodium chloride or potassium chloride, and were excellent in all of blending stability, low-temperature storage stability (including seed crystal test), and electrical conductivity. In contrast, when other salts, specifically ammonium chloride, sodium metasilicate, potassium silicate No. 1, sodium carbonate, potassium carbonate, sodium sulfate, or sodium citrate, were blended in place of sodium chloride and potassium chloride while keeping the other compositions the same, it was not possible to obtain a cleaning liquid composition excellent in all of blending stability, low-temperature storage stability (including seed crystal test), and electrical conductivity, regardless of the content (Comparative Examples 2 to 20).

[0058] From the above, it was found that by blending sodium chloride and / or potassium chloride in a liquid detergent composition containing sodium hydroxide and / or potassium hydroxide, it is possible to impart high conductivity when diluted while maintaining the storage stability of the detergent. This shows that by blending sodium chloride and / or potassium chloride, it is possible to easily develop a formulation of a liquid detergent for automatic dishwashers containing sodium hydroxide and / or potassium hydroxide that has sufficiently high conductivity even when diluted at a high ratio and also has high storage stability when concentrated. [Industrial Applicability]

[0059] According to the present invention, it is possible to easily design a liquid detergent for automatic dishwashers that has a sufficiently high conductivity even when diluted at a high ratio and also has high storage stability when concentrated. Therefore, it is possible to provide a liquid detergent for automatic dishwashers that has a sufficiently high conductivity even when diluted at a high ratio and also has high storage stability when concentrated.

Claims

1. (A) sodium hydroxide and / or potassium hydroxide and (B) sodium chloride and / or potassium chloride, (A) the total content of sodium hydroxide and / or potassium hydroxide is 4% by mass or more, and the content of each of sodium hydroxide and potassium hydroxide is 5% by mass or less; (B) the total content of sodium chloride and / or potassium chloride is 5% by mass or more; A liquid detergent composition for automatic dishwashing machines.

2. 2. The liquid detergent composition for automatic dishwashers according to claim 1, which has a pH of 11.0 or more.

3. The liquid detergent composition for automatic dishwashers according to claim 1, further comprising a polymer dispersant and / or a chelating agent.

4. A method for washing tableware with an automatic dishwashing machine, comprising washing tableware with the liquid detergent composition for automatic dishwashing machines according to claim 1.

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