Liquid detergent composition and washing method using the same

Abstract

To find a formulation for a liquid detergent containing a protease that can improve storage stability of the protease and has appearance stability.SOLUTION: The liquid detergent composition of the present invention comprises (A) a protease and (B) dihydroxyethylglycine or a salt thereof.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a liquid detergent composition and a cleaning method using the liquid detergent composition. [Background technology]

[0002] Automatic washing machines remove dirt from dirty objects (such as dishes or medical equipment) by spraying a diluted detergent solution (cleaning liquid) made by diluting a special detergent with a high-pressure water jet onto the surface of the dirty object. In order to effectively remove dirt by spray washing, automatic washing machines, mainly for commercial use, have traditionally used strong alkaline liquid detergents containing alkaline agents. This is because the strong alkali has the ability to break down and solubilize protein stains, enabling speedy and efficient cleaning.

[0003] Meanwhile, in recent years, there has been a growing need to switch from strongly alkaline liquid detergents to neutral to weakly alkaline ones, driven by SDGs and environmental concerns. However, neutralizing detergents (neutral to weakly alkaline) eliminates the strong alkali's ability to decompose and solubilize proteinaceous soils. Instead, incorporating proteases into liquid detergents can enhance their cleaning power against proteinaceous soils (see, for example, Patent Document 1). However, proteases, which are enzymes, can suffer from a decline in protease activity over long-term storage. Therefore, when incorporating proteases into liquid detergents, there is a need to improve the storage stability of the proteases (note that this need is not limited to liquid detergents for automatic washing machines). Furthermore, liquid detergents typically require stable appearance.

[0004] Incidentally, when setting up a commercial automatic washing machine, an initial adjustment of the automatic detergent dilution mechanism of the automatic washing machine is required. Therefore, a method for easily measuring the detergent concentration in the diluted detergent solution (cleaning liquid) is required for detergents used in automatic washing machines. Conventionally, when using a strongly alkaline liquid detergent containing an alkaline agent, it has been simple and common to measure the detergent concentration in the diluted detergent solution (cleaning liquid) by performing concentration titration using phenolphthalein, using the alkaline agent concentration as an indicator. However, for neutral to weakly alkaline detergents, using phenolphthalein as an indicator is not necessarily suitable. Currently, there is no commonly used method for measuring the concentration of neutral to weakly alkaline detergents. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2023-161601 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention was made in consideration of the above circumstances, and the object of the present invention is to find a formulation in a liquid detergent containing a protease that can increase the storage stability of the protease and also maintain appearance stability. [Means for solving the problem]

[0007] The present inventors have conducted extensive research to find a solution to the above-mentioned problems, and have unexpectedly found that by incorporating dihydroxyethylglycine into a liquid detergent containing a protease, the storage stability of the protease can be improved and the appearance of the protease can be stabilized. The present invention has been made based on the above findings, and the gist of the present invention is as follows.

[0008] In addition to the above findings, the inventors have unexpectedly found that a combination of protease and dihydroxyethylglycine has excellent detergency against blood stains. Furthermore, they have unexpectedly found that the concentration of a liquid detergent containing dihydroxyethylglycine can be effectively titrated using bromocresol green (BCG) in the neutral to weakly alkaline range, thereby enabling easy concentration control of the detergent. One aspect of the present invention is based on the above findings.

[0009] [1] A liquid detergent composition comprising (A) a protease and (B) dihydroxyethylglycine or a salt thereof. [2] The liquid detergent composition according to [1], which has a pH in the range of 6.0 to 11.0. [3] The liquid detergent composition according to [1] or [2], further comprising at least one selected from the group consisting of a nonionic surfactant, an amphoteric surfactant, an anionic surfactant, a water-soluble solvent, a polymer dispersant, and a rust inhibitor. [4] The liquid detergent composition according to any one of [1] to [3], which is for cleaning tableware or medical instruments. [5] The liquid detergent composition according to any one of [1] to [4], which is for use in an automatic cleaning machine. [6] A method for cleaning tableware or medical instruments, comprising using the liquid detergent composition according to any one of [1] to [5] to clean tableware or medical instruments. [7] A method for measuring the concentration of a liquid detergent in a diluted liquid detergent solution, comprising: The liquid detergent contains dihydroxyethylglycine or a salt thereof, This involves neutralization titration of diluted liquid detergent with bromocresol green. method.

[0010] It should be noted that any two or more of the above configurations [1] to [7] can be selected and combined. [Effects of the Invention]

[0011] The present invention can provide a liquid detergent composition that contains dihydroxyethylglycine in addition to a protease, thereby ensuring excellent storage stability of the protease and stable appearance. DETAILED DESCRIPTION OF THE INVENTION

[0012] The present invention will be described in detail below. The terms used in this specification are to be interpreted in the sense commonly used in the art unless otherwise specified.

[0013] <Liquid detergent composition> The liquid detergent composition of the present invention contains (A) a protease and (B) dihydroxyethylglycine or a salt thereof. The liquid detergent composition of the present invention contains dihydroxyethylglycine in addition to the protease, thereby providing excellent storage stability of the protease and maintaining stable appearance. Furthermore, for example, the liquid detergent composition of the present invention contains a combination of the protease and dihydroxyethylglycine, thereby providing excellent detergency against blood stains. Furthermore, for example, the liquid detergent composition of the present invention contains dihydroxyethylglycine, which allows for easy measurement of the detergent concentration even in the neutral to weakly alkaline range.

[0014] [(A) Protease] The liquid detergent composition of the present invention contains (A) a protease. Protease is an enzyme with proteolytic activity, and the liquid detergent composition of the present invention contains a protease to impart cleaning power to protein stains. Furthermore, the combination of the protease and dihydroxyethylglycine in the present invention exhibits excellent cleaning power against blood stains.

[0015] In the present invention, proteases known in the art can be widely used without particular limitation, and for example, commercially available proteases can be used. In addition, proteases with an optimum pH in the neutral to weakly alkaline range (e.g., pH 6.0 to 11.0) can be preferably used in the present invention.

[0016] Examples of commercially available proteases include the Alcalase (registered trademark) series, Savinase (registered trademark) series, Everlase (registered trademark) series, Liquanase (registered trademark) series, and Progress (registered trademark) series (manufactured by Novonesys); the PREFERENZ (registered trademark) series and EXCELLENZ (registered trademark) series (manufactured by Danisco); the Lavergy (registered trademark) series (manufactured by BASF); and the Samoase (registered trademark) series (manufactured by Amano Enzyme).

[0017] In the liquid detergent composition of the present invention, the proteases may be used singly or in combination of two or more kinds.

[0018] The content of (A) protease in the liquid detergent composition of the present invention is not particularly limited, and can be incorporated in an appropriate amount as long as the effects of the present invention are achieved. From the viewpoint of detergency, the lower limit of the content of (A) protease is preferably 0.001% by mass or more, more preferably 0.005% by mass or more, and even more preferably 0.01% by mass or more. From the viewpoint of formulation stability of the detergent, the upper limit of the content of (A) protease is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less. The numerical range of the content of (A) protease is preferably 0.001% by mass or more and 50% by mass or less, more preferably 0.005% by mass or more and 40% by mass or less, and even more preferably 0.01% by mass or more and 30% by mass or less. In the present invention, the protease can be, for example, a protease liquid (protease preparation), and the content of the protease in the present invention is based on the pure content of the protease.

[0019] [(B) Dihydroxyethylglycine or a salt thereof] The liquid detergent composition of the present invention contains (B) dihydroxyethylglycine or a salt thereof. Dihydroxyethylglycine is known as a glycine-based chelating agent. In the present invention, when dihydroxyethylglycine is combined with a protease in the liquid detergent composition, the storage stability of the protease is improved. Furthermore, the combination of protease and dihydroxyethylglycine in the present invention exhibits excellent detergency against blood stains. Furthermore, the dihydroxyethylglycine in the liquid detergent composition of the present invention increases the titration amount (number of drops) in concentration titration using bromocresol green (BCG) in the neutral to weakly alkaline range, enabling simple concentration control in the neutral to weakly alkaline range.

[0020] The dihydroxyethylglycine in the present invention is N,N-di(2-hydroxyethyl)glycine.

[0021] Examples of the salt of dihydroxyethylglycine in the present invention include the sodium salt (sodium dihydroxyethylglycine) and the potassium salt (potassium dihydroxyethylglycine).

[0022] As dihydroxyethylglycine or a salt thereof in the present invention, specifically, commercially available products such as Chelest G-50 (dihydroxyethylglycine sodium) manufactured by Chelest Corporation can be used.

[0023] In the liquid detergent composition of the present invention, dihydroxyethylglycine or a salt thereof may be used alone or in combination of two or more types.

[0024] The content of (B) dihydroxyethylglycine or a salt thereof in the liquid detergent composition of the present invention is not particularly limited, and can be incorporated in an appropriate amount as long as the effects of the present invention are achieved. From the viewpoint of the storage stability of the enzyme, the lower limit of the content of (B) dihydroxyethylglycine or a salt thereof is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and even more preferably 0.5% by mass or more. From the viewpoint of the formulation stability of the detergent, the upper limit of the content of (B) dihydroxyethylglycine or a salt thereof is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less. The numerical range of the content of (B) dihydroxyethylglycine or a salt thereof is preferably 0.01% by mass or more and 50% by mass or less, more preferably 0.1% by mass or more and 40% by mass or less, and even more preferably 0.5% by mass or more and 30% by mass or less. The content of (B) dihydroxyethylglycine or a salt thereof is expressed as a value converted to the sodium salt.

[0025] The mass ratio of (A) protease to (B) dihydroxyethylglycine or a salt thereof [(A) / (B)] in the liquid detergent composition of the present invention is not particularly limited and can be adjusted as appropriate. From the viewpoint of storage stability, however, it is preferably, for example, 0.0001 to 1000, more preferably 0.0005 to 100, even more preferably 0.001 to 50, and particularly preferably 0.005 to 10.

[0026] In addition to the above components, the liquid detergent composition of the present invention may contain, as needed, surfactants (e.g., nonionic surfactants, amphoteric surfactants, anionic surfactants, cationic surfactants), polymeric dispersants, chelating agents, enzymes, colorants, bactericides, water-soluble solvents, antifoaming agents, bleaching agents, bleach activators, antioxidants, disinfectants, fragrances, rust inhibitors (also called metal corrosion inhibitors), preservatives, pH adjusters, etc., as long as the effects of the present invention are achieved. Among these, the liquid detergent composition of the present invention preferably contains at least one selected from the group consisting of nonionic surfactants, amphoteric surfactants, anionic surfactants, water-soluble solvents, polymeric dispersants, and rust inhibitors.

[0027] The liquid detergent composition of the present invention contains, for example, water as the balance other than the above components. 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, and hard water.

[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, 6.0 to 11.0 at 25°C, preferably 7.0 to 10.0, and more preferably 7.5 to 9.5.

[0030] [Cleaning target] The liquid detergent composition of the present invention is preferably used for cleaning, for example, tableware or medical instruments (i.e., for cleaning tableware or medical instruments). Here, tableware as the object to be cleaned (object to be cleaned) with the liquid detergent composition of the present invention refers to, for example, objects that can be cleaned in a so-called automatic dishwasher, such as tableware, cooking utensils, trays, bottles, cans, etc. Furthermore, medical instruments as the object to be cleaned (object to be cleaned) include, for example, steel instruments such as scissors, forceps, and tweezers, resin instruments such as catheters, tubes, and bite blocks, rigid or flexible endoscopes, etc. The liquid detergent composition of the present invention has excellent detergency against blood stains, and therefore can be suitably used for cleaning medical instruments.

[0031] [Automatic washing machine applications] The liquid detergent composition of the present invention is preferably used, for example, in commercial or domestic automatic washing machines. That is, since the concentration of the liquid detergent composition of the present invention can be easily measured, it can be suitably used in automatic washing machines (e.g., commercial automatic washing machines) where the concentration of the detergent in the washing liquid needs to be measured, adjusted, managed, etc. Note that there are no particular limitations on the automatic washing machines in which the liquid detergent composition of the present invention can be used, and it can be used, for example, in commercial or domestic automatic dishwashers, washer disinfectors, etc.

[0032] However, the liquid detergent composition of the present invention is not limited to the above-mentioned use in automatic washing machines, and can also be used, for example, as a liquid detergent for hand washing. That is, the liquid detergent composition of the present invention can be diluted with water to a predetermined ratio to prepare a diluted detergent solution, and the diluted detergent solution can be used to hand wash an object to be washed. Here, hand washing includes a cleaning method in which the object to be washed is scrubbed with a cleaning tool such as a sponge to which the liquid detergent is attached, followed by rinsing with water, and a cleaning method in which the liquid detergent is dispersed in water to prepare an immersion liquid, the object to be washed is immersed in this immersion liquid, left for a certain period of time, and then rinsed with water. These scrubbing and immersion washing methods can be used appropriately depending on the object to be washed.

[0033] The liquid detergent composition of the present invention can also be used in aeration cleaning, immersion cleaning, vacuum boiling cleaning, and the like.

[0034] <Cleaning method> The cleaning method using the liquid detergent composition of the present invention (hereinafter, sometimes simply referred to as the cleaning method) is characterized by cleaning an object to be cleaned using the liquid detergent composition of the present invention, and other steps, conditions, etc. are not limited. The above description of the liquid detergent composition of the present invention can be used to explain this cleaning method.

[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, preferably 10 to 20,000, more preferably 50 to 10,000, and even more preferably 100 to 5,000. The concentration of the liquid detergent composition of the present invention in the diluted detergent solution is, for example, 0.001 to 50% by mass, preferably 0.005 to 10% by mass, more preferably 0.01 to 2% by mass, and even more preferably 0.02 to 1% by mass.

[0037] The cleaning method of the present invention can be, for example, a cleaning method using an automatic cleaning machine. In this case, the cleaning method of the present invention includes, for example, a spray cleaning step in which a diluted solution of the liquid cleaning composition of the present invention is sprayed onto items to be cleaned stored in the automatic cleaning machine cabinet.

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

[0039] In the cleaning method of the present invention, the cleaning time can be set appropriately, and is, for example, from 1 second to 96 hours.

[0040] <Method for measuring the concentration of liquid detergent in diluted solution> The method for measuring the concentration of a liquid detergent in a diluted solution of the present invention (hereinafter sometimes simply referred to as the measurement method) is characterized in that, when the liquid detergent contains dihydroxyethylglycine or a salt thereof, the concentration of the liquid detergent in the diluted solution is measured by neutralization titration of the diluted liquid detergent with bromocresol green, and other steps, conditions, etc. are not limited. The description of the liquid detergent composition of the present invention above can be used to explain this measurement method (however, in this measurement method, protease is an optional component of the liquid detergent (liquid detergent composition)).

[0041] The measurement method of the present invention can measure the concentration of a liquid detergent in a diluted liquid detergent solution (i.e., a liquid detergent concentrate). Therefore, it can also be said that the measurement method of the present invention can measure, for example, the dilution ratio of a liquid detergent concentrate.

[0042] The measurement method of the present invention measures the concentration of dihydroxyethylglycine or its salts derived from the original liquid detergent solution in a diluted liquid detergent solution by neutralization titration. As shown in the examples below, when an aqueous solution containing dihydroxyethylglycine or its salts is subjected to neutralization titration with dilute hydrochloric acid using bromocresol green as an indicator, the titration amount (number of drops) can be increased. Therefore, the concentration of a diluted liquid detergent solution containing dihydroxyethylglycine or its salts can be effectively measured by neutralization titration using bromocresol green.

[0043] In the measurement method of the present invention, bromocresol green is used as an indicator for neutralization titration. The indicator is not limited to bromocresol green, and a wide range of bromocresol green-based indicators can be used, such as a mixed indicator such as bromocresol green / methyl red.

[0044] In the measurement method of the present invention, the titration reagent can be any titration reagent commonly used in neutralization titration, without any particular limitation. For example, an acid (strong acid or weak acid) can be used, and preferably, dilute hydrochloric acid or dilute sulfuric acid can be used. [Example]

[0045] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0046] Protease-containing liquid detergent compositions having the compositions shown in Table 1 below were prepared and subjected to the following tests. The components used in the formulation are listed below. In the following, "%" represents % by mass unless otherwise specified. The values ​​in parentheses in Table 1 are values ​​converted to pure content.

[0047] [Ingredients] <Protease> Protease solution: Product name "Liquanase everis 900L" (protease content 5-7.5%), manufactured by Novonesis <Chelating agent> 50% dihydroxyethylglycine sodium solution: Trade name "Chilest G-50", manufactured by Chelest Co., Ltd. 20% disodium hydroxyethyliminodiacetate solution: Trade name "Chilest E-20", manufactured by Chelest Co., Ltd. Nitrilotriacetic acid trisodium salt: Trade name "Chilest 700", manufactured by Chelest Co., Ltd. Ethylenediaminetetraacetic acid tetrasodium salt: Trade name "Chilest 2D", manufactured by Chelest Co., Ltd. 40% trisodium methylglycine diacetate solution: Trade name "Disolvine M-40", manufactured by Nouryon 47% tetrasodium glutamate diacetate solution: Trade name "Disolvine GL-47-S", manufactured by Nouryon <Alkanolamine> Triethanolamine: Oxalis Chemicals 2-Amino-2-methyl-1-propanol: Angus Chemical Co. <Glycine derivatives> Trimethylglycine: manufactured by Danisco <Amino acids> Glycine: manufactured by Resonac

[0048] [Concentration titration test] First, each liquid detergent composition was diluted with tap water to prepare a 0.04% by mass diluted detergent solution. Next, 5 drops of bromocresol green (BCG) / methyl red solution were added to 20 mL of the diluted detergent solution. Neutralization titration was performed by adding 0.02 M hydrochloric acid drop by drop using a 5 mL all-plastic syringe (manufactured by Henke) to the diluted detergent solution, and the titration was terminated when the color of the solution changed from green to red. Meanwhile, neutralization titration was also performed in the same manner on tap water not containing the liquid detergent composition. The difference between the titration amount (number of drops) for the diluted detergent solution and the titration amount (number of drops) for tap water was defined as the titration difference. ○: Titration difference is 11 drops or more. ×: Titration difference is 10 drops or less.

[0049] [Appearance stability test] Each liquid detergent composition was prepared as described above and then stored at 50°C for 6 days. After storage, the appearance was visually observed and the appearance stability was evaluated. The evaluation criteria were as follows: ○: No discoloration occurred. ×: Discoloration occurred.

[0050] [Enzyme storage stability test] Each liquid detergent composition was prepared as described above and then stored at 50°C for 6 days. After storage, the residual protease activity in the liquid detergent composition was measured using Protazyme AK (Megazyme). A 10% aqueous solution of protease (Liquanase everis 900L) was prepared, and the protease activity immediately after preparation was similarly measured using Protazyme AK. The ratio of the protease activity of the liquid detergent composition after storage to the protease activity of the aqueous protease solution immediately after preparation was calculated using the following formula, and this was defined as the residual activity rate (%). Residual activity rate (%) = {(protease activity after storage) / (protease activity immediately after preparation)} x 100 The residual protease activity of each liquid detergent composition was evaluated as follows. ○: Residual activity rate is 90% or more. ×: Residual activity rate is less than 90%.

[0051] [Blood washing speed test] Each liquid detergent composition was diluted 200 times with tap water to prepare a cleaning solution (0.5% diluted solution), and the blood cleaning speed was evaluated using a TOSI cleaning evaluation indicator (model stain: bovine blood) manufactured by PEREG GmbH. Specifically, the indicator was immersed in each cleaning solution (0.5% diluted solution) at 40°C, and the liquid temperature was maintained at 40°C. The time until the blood stain on the indicator was completely removed was measured, and the evaluation was based on the following criteria. ◎: The stain was completely removed within 40 minutes. ○: The stain was completely removed within 40 to 60 minutes. ×: The stain was not completely removed within 60 minutes.

[0052] [Table 1]

[0053] The results of the concentration titration test, appearance stability test, enzyme storage stability test, and blood washing speed test are shown in Table 1.

[0054] As shown in Table 1, Example 1, a liquid detergent composition containing protease and dihydroxyethylglycine, was excellent in both appearance stability and enzyme storage stability. In contrast, liquid detergent compositions containing other chelating agents or alkanolamines instead of dihydroxyethylglycine were inferior in either appearance stability or enzyme storage stability. Since chelating agents are generally known to reduce enzyme storage stability, the effect of the chelating agent dihydroxyethylglycine in improving enzyme storage stability was surprising.

[0055] Furthermore, Example 1 had the fastest blood cleaning speed and excellent cleaning power against blood stains. Furthermore, as shown in the concentration titration test, Example 1 was able to increase the appropriate amount (number of drops) in the neutralization titration using bromocresol green.

[0056] From the above, it was found that the liquid detergent composition containing protease and dihydroxyethylglycine has stable appearance and excellent storage stability of the protease. Furthermore, it was found that this liquid detergent composition has excellent detergency against blood stains. Furthermore, it was found that this liquid detergent composition is suitable for concentration titration using bromocresol green (BCG). [Industrial Applicability]

[0057] According to the present invention, a liquid detergent composition can be provided which has excellent storage stability of protease and stable appearance.

Claims

1. A liquid detergent composition comprising (A) a protease and (B) dihydroxyethylglycine or a salt thereof.

2. 2. The liquid detergent composition according to claim 1, wherein the pH is in the range of 6.0 to 11.

0.

3. 2. The liquid detergent composition according to claim 1, further comprising at least one selected from the group consisting of a nonionic surfactant, an amphoteric surfactant, an anionic surfactant, a water-soluble solvent, a polymer dispersant, and a rust inhibitor.

4. The liquid detergent composition according to claim 1, which is used for cleaning dishes or medical instruments.

5. The liquid detergent composition according to claim 1, which is for use in automatic washing machines.

6. A method for cleaning tableware or medical instruments, comprising cleaning tableware or medical instruments with the liquid detergent composition according to claim 1.

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