Detergent composition and recirculation system

Abstract

The present invention provides a cleaning agent composition for cleaning a member or the like having a metal working oil or the like attached thereto, which has high cleaning power, less harmfulness to the cleaning agent, less fire risk, and excellent recyclability other than distillation, and a power-saving recycling system for recycling the cleaning agent composition by means other than distillation. The recycling system of the cleaning agent composition includes: a step (1) of maintaining a cleaning agent composition containing a water-insoluble solvent, water in a range of 60% or more and less than 90% by volume, and exhibiting a cloud point of 20°C to 70°C at a temperature above the cloud point, and dispersing the solvent component of the cleaning agent composition in water to clean a cleaning target; a step (2) of cooling the cleaned cleaning agent composition to below the cloud point to separate a dirt from the cleaning agent composition; a step (3) of removing the dirt separated from the cleaning agent composition by a separation means other than distillation; and a step (4) of recycling the cleaning agent composition from which the dirt is removed to the above step (1) for a non-cleaning target.

Description

Technical Field

[0001] This disclosure relates to a cleaning agent composition and a recycling system thereof that removes processing oils and other contaminants adhering to processed parts, articles, etc., in various industrial fields and can be recycled by means other than distillation. More specifically, it relates to a recycling system that, after cleaning articles with a cleaning agent composition containing water and exhibiting a cloud point, separates the contaminant components mixed in the cleaning agent composition from the cleaning agent composition by means other than distillation. Background Technology

[0002] In various industrial fields such as automobiles, machinery, precision instruments, electrical, and electronics, the parts processed are manufactured using various metalworking oils, fluxes, and other processing agents. Parts with these agents (hereinafter referred to as "dirt") are usually cleaned before further processing and productization.

[0003] In cleaning dirt, various cleaning agents and systems are used, such as water-based, semi-water-based, halogen-based, hydrocarbon-based, and solvent-based cleaning agents. However, a cleaning system that is completely satisfactory in terms of the safety of the cleaning agent, cleaning power, recyclability, and power consumption does not exist.

[0004] Water-based cleaning agents and near-water-based cleaning agents, which contain surfactants, are difficult to separate from dirt through distillation, making them essentially non-recyclable. Cleaning is performed while the cleaning agent is periodically replaced. This results in cumbersome replacement procedures and the generation of a considerable amount of waste liquid.

[0005] While surfactant-free cleaning agents such as halogenated, hydrocarbon-based, and solvent-based cleaning agents can be recycled through distillation by taking advantage of the large boiling point difference between them and high-boiling-point dirt, halogenated cleaning agents have problems such as harmfulness, regulatory restrictions, or high cost. Hydrocarbon-based and solvent-based cleaning agents are flammable and pose a high risk of fire. Therefore, it is necessary to fully control the cost of purchasing explosion-proof devices, fire prevention equipment, and other equipment.

[0006] To address these issues, cleaning agents have been proposed that eliminate flammability by mixing with water in a water-soluble solvent and that are free of surfactants. However, all recyclable cleaning agents can be recycled through distillation, thus requiring energy corresponding to the boiling point and latent heat of vaporization of the cleaning agent, resulting in high electricity consumption and a significant environmental impact. (Refer to Patent Documents 1-4)

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: International Publication No. 2015 / 060379

[0010] Patent Document 2: Japanese Patent Application Publication No. 2019-052277

[0011] Patent Document 3: Japanese Patent Application Publication No. 2019-031690

[0012] Patent Document 4: Japanese Patent Application Publication No. 2013-129815 Summary of the Invention

[0013] The problem the invention aims to solve

[0014] The purpose of this disclosure is to provide a cleaning agent composition that has high cleaning power, low harmfulness of the cleaning agent, low fire hazard, and excellent recyclability (except for distillation) in cleaning parts with dirt such as metalworking oil, and to provide an energy-saving recycling system that recycles the cleaning agent by means other than distillation.

[0015] Solution for solving the problem

[0016] In view of the above, the inventors have conducted various studies to solve the above problems, and as a result, they discovered the target cleaning agent composition and its recycling system, thus completing the present invention.

[0017] That is, this disclosure includes the embodiments shown below.

[0018] [1] A cleaning agent composition comprising a water-insoluble solvent and water, wherein the water content is in the range of 60% to less than 90% by volume, and exhibits a cloud point of 20°C to 70°C.

[0019] [2] According to the cleaning agent composition described in [1] above, the water-insoluble solvent is a solvent that is not soluble in water in any proportion at 70°C and has a concentration of 1g / 100g or more.

[0020] [3] According to the cleaning agent composition described in [1] above, the water-insoluble solvent is one or more selected from the group consisting of diethylene glycol methyl propyl ether, diethylene glycol methyl butyl ether, diethylene glycol diethyl ether, dipropylene glycol dimethyl ether, ethylene glycol hexyl ether, diethylene glycol hexyl ether, propylene glycol butyl ether, dipropylene glycol propyl ether, propyl lactate and butyl lactate.

[0021] [4] The cleaning agent composition according to [1] or [2] above further comprises a water-soluble solvent.

[0022] [5] The cleaning agent composition according to [4] above, wherein the water-soluble solvent is a solvent that is dissolved in water in any proportion.

[0023] [6] According to the cleaning agent composition described in [4] above, the water-soluble solvent is selected from one or more of the following: ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monoisobutyl ether, propylene glycol monopropyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, ethylene glycol, diethylene glycol, propylene glycol, 3-methoxy-1-butanol, 3-methoxy-3-methylbutanol, etc.; methyl lactate, ethyl lactate, tetrahydrofurfuryl alcohol, furfuryl alcohol, 2-dimethyl-1,3-dioxolane-4-methanol, γ-butyrolactone and diacetone alcohol.

[0024] [7] A recycling system for a cleaning agent composition, comprising:

[0025] Step (1) involves maintaining the cleaning agent composition described in any one of [1] to [6] at a temperature above the cloud point and dispersing the solvent component of the cleaning agent composition in water to clean the object to be cleaned.

[0026] Step (2) involves cooling the cleaned cleaning agent composition to below its cloud point to separate the dirt from the cleaning agent composition phase.

[0027] Step (3) involves removing the contaminants separated from the cleaning agent composition phase using separation methods other than distillation; and

[0028] Step (4) involves reusing the cleaning agent composition that has removed dirt in step (1) of the same process as the object being cleaned.

[0029] [8] According to the recycling system described in [5] above, in step (3), the means other than distillation is a separation means selected from at least one of gravity separators, coalescers, centrifuges, filter membranes and adsorption towers.

[0030] [9] According to the recycling system described in [8] above, the filter membrane is a hollow fiber membrane.

[0031]

[10] The recycling system according to any one of [7] to [9] above, wherein the item being cleaned is an article with non-water-soluble dirt attached.

[0032] The effects of the invention

[0033] According to this disclosure, a cleaning agent composition and its recycling system can be provided that have high cleaning power, low harmfulness of the cleaning agent, low fire hazard, excellent recyclability (except for distillation), and can perform cleaning in a power-saving manner when cleaning parts with dirt attached. Detailed Implementation

[0034] The cleaning agent composition and its recycling system according to one aspect of the present invention will be described in detail below.

[0035] In this disclosure, the cleaning agent composition comprises a water-insoluble solvent and water, wherein the water content is in the range of 60% by volume or more and less than 90% by volume, and exhibits a cloud point of 20°C to 70°C.

[0036] In this disclosure, the cloud point refers to the temperature at which a transparent solution becomes turbid due to a change in temperature. Similar to the phenomenon known in aqueous solutions of nonionic surfactants, it refers to the temperature at which, when the temperature of an aqueous solution is increased, the solution begins to turn cloudy as the solvent-dominant phase and the water-dominant phase separate.

[0037] In this invention, from the perspective of the separability of dirt and cleaning agent, a high water concentration in the cleaning agent composition is preferred. Furthermore, a high degree of effectiveness in eliminating the flash point of the solvent mixed with the cleaning agent is desirable. Cleaning agent compositions with less than 60% by volume become insufficient to separate dirt from the cleaning agent when cooled below their cloud point, resulting in poor recyclability. If the water concentration exceeds 90% by volume, the cloud point of the cleaning agent rises rapidly above 70°C as the water concentration increases, eventually ceasing to be visible, making cleaning difficult.

[0038] The cloud point of the cleaning agent composition ranges from 20°C to 70°C. Below 20°C, cooling methods for separating dirt require lower temperatures, increasing energy consumption. Above 70°C, cleaning above this level requires higher temperatures, leading to significant water evaporation, drastic fluctuations in water concentration, increased management complexity, and further energy consumption.

[0039] Considering these aspects, the moisture content of the cleaning agent composition is in the range of 60% to less than 90% by volume, and its cloud point is in the range of 20°C to 70°C, more preferably in the range of 30°C to 60°C.

[0040] It should be noted that the cleaning agent composition used in this invention has a high water concentration and no flash point (based on the confirmation test of Class IV hazardous materials under the Fire Protection Act), thus posing less of a fire hazard and is therefore preferred.

[0041] In this invention, the cleaning agent composition exhibits a cloud point within the aforementioned specific range. However, such a cleaning agent composition is composed of a solvent having a solubility in water at 70°C of approximately 1 g / 100 g or more, a solvent that is not soluble in water in any proportion (hereinafter referred to as a "water-poorly soluble solvent"), or a solvent obtained by further mixing a water-poorly soluble solvent with a solvent soluble in water in any proportion (hereinafter referred to as a "water-soluble solvent"). Non-water-soluble solvents such as alkanes, cycloalkanes, and aromatic hydrocarbons have extremely low water solubility and do not exhibit a cloud point, therefore they are unsuitable.

[0042] Examples of water-insoluble solvents include glycol diethers such as diethylene glycol methyl propyl ether, diethylene glycol methyl butyl ether, diethylene glycol diethyl ether, dipropylene glycol dimethyl ether, and triethylene glycol dimethyl ether; glycol ethers such as ethylene glycol hexyl ether, diethylene glycol hexyl ether, propylene glycol butyl ether, and dipropylene glycol propyl ether; and lactic acid esters such as propyl lactate and butyl lactate. One or more of these solvents can be used.

[0043] Among them, cleaning agent compositions containing glycol diethers such as diethylene glycol methyl propyl ether, diethylene glycol methyl butyl ether, diethylene glycol diethyl ether, and dipropylene glycol dimethyl ether have high cleaning power above the cloud point and better separation from dirt, and can be preferred for use.

[0044] In addition, cleaning agent compositions containing water-insoluble glycol ethers such as ethylene glycol hexyl ether, diethylene glycol hexyl ether, propylene glycol butyl ether, and dipropylene glycol propyl ether, as well as water-insoluble lactic acid esters such as propyl lactate and butyl lactate, have the effect of suppressing the rise in cloud point associated with an increase in water concentration. Therefore, by mixing with other solvents, the cloud point of the cleaning agent can be further expanded to a water concentration range of 20°C to 70°C, which is more preferable for use.

[0045] In this disclosure, when the cleaning agent composition contains only a water-insoluble solvent, the cloud point may not always be within the range of 20°C to 70°C across the entire range of water concentrations between 60% and 90% by volume. If the cloud point is below this range at a certain water concentration, the cloud point range can be adjusted to the aforementioned range by mixing in a water-insoluble solvent with higher water solubility or a water-soluble solvent. Conversely, if the cloud point is high at a certain water concentration, the cloud point range can be adjusted to the range of the present invention by mixing in a water-insoluble solvent with lower water solubility.

[0046] As a water-soluble solvent, there are no particular restrictions as long as it is a water-soluble solvent that dissolves in water in any proportion at approximately 20°C. However, depending on the mixing ratio, it may lead to the appearance of flash point and deterioration of drying properties. Therefore, solvents with a boiling point of approximately 150°C or higher and below 230°C are preferred. Examples include ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, and diethylene glycol. Diol ethers such as monoisobutyl ether, propylene glycol monopropyl ether, dipropylene glycol monomethyl ether, and dipropylene glycol monoethyl ether; diols such as ethylene glycol, diethylene glycol, and propylene glycol; methoxybutanols such as 3-methoxy-1-butanol and 3-methoxy-3-methylbutanol; lactate esters such as methyl lactate and ethyl lactate; cyclic ether alcohols such as tetrahydrofurfuryl alcohol, furfuryl alcohol, and 2-dimethyl-1,3-dioxolane-4-methanol; and γ-butyrolactone and diacetone alcohol, etc. One or more of these can be used.

[0047] These water-insoluble and water-soluble solvents are preferably solvents with a boiling point of 150°C or higher. If the boiling point is below 150°C, the flash point will not disappear even when mixed with water, increasing the risk of fire. Furthermore, if the boiling point exceeds 230°C, drying after cleaning becomes difficult, requiring rinsing and replacement with pure water or other low-boiling-point solvents.

[0048] In this invention, the cleaning agent composition has a high water concentration and is used at relatively high temperatures above the cloud point. Therefore, depending on the usage conditions, it is prone to oxidative degradation of the cleaning agent and corrosion of the metal objects being cleaned. More preferably, antioxidants such as 2,6-di-tert-butyl-p-cresol, thymol, methoxyphenol, n-propyl gallate, and hydroquinone, as well as corrosion inhibitors such as benzotriazole, toluenetriazole, and imidazoles, are further added within the range that does not deviate from the characteristics of the cleaning agent composition.

[0049] In this invention, without departing from the characteristics of the cleaning agent composition, it may further include surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkylphenols, polyoxyethylene fatty acid esters, ethylene oxide propylene oxide polymers, polyoxyethylene alkylphenols, and polyol fatty acid esters.

[0050] In this invention, other polyol derivatives, esters, ethers, amines, amides, etc., may be included without impairing the performance of the cleaning agent composition.

[0051] In this disclosure, the cleaning agent composition can be applied not only to dirt such as processing oil, but also to dirt that is difficult to dissolve in water, such as flux, wax, grease, ink, resist, and buff.

[0052] In this disclosure, the recycling system for the cleaning agent composition includes: step (1), maintaining the cleaning agent composition at a temperature above the cloud point and dispersing the solvent component of the cleaning agent composition in water to clean the object to be cleaned; step (2), cooling the cleaned cleaning agent composition to below the cloud point and separating the dirt from the cleaning agent composition phase; step (3), removing the dirt separated from the cleaning agent composition phase using a separation means other than distillation; and step (4), reusing the cleaning agent composition with the dirt removed in step (1) on a non-cleaned object.

[0053] In this disclosure, for the recycling system, after the object to be cleaned is cleaned, the cleaning agent composition is cooled to a temperature below the cloud point, causing the dirt contained in the cleaning agent to separate into phases, and the phase-separated dirt is removed from the cleaning agent composition for recycling.

[0054] When cleaning an object at a temperature above its cloud point, the cleaning agent composition undergoes phase separation into a solvent-based phase and a water-based phase. By cooling the mixture below its cloud point, the solvent and water phases homogenize, reducing the solubility of the dirt and causing it to separate into a cleaning agent phase and a dirt-based phase. The separated dirt phase is then separated from the cleaning agent phase using a removal process and recycled to the cleaning process.

[0055] In step (2), the cooling temperature only needs to be lower than the cloud point of the cleaning agent composition, but the separation of dirt is improved if it is lower than the cloud point. Therefore, it is preferable to be 5°C or less lower than the cloud point, and more preferably 10°C or less lower than the cloud point. Even if cooled to a lower temperature, the separation performance does not change much. Therefore, it is preferable to cool to a temperature approximately 5°C to 20°C lower than the cloud point.

[0056] For cooling the cleaning agent composition, if the temperature naturally drops below the cloud point after cleaning, no special cooling method is needed. However, if a heat exchanger such as an air cooler or a water cooler is available, rapid cooling can be achieved. As a heat exchanger, conventional heat exchangers such as finned tube type, plate type, coil type, and shell and tube type can be used, for example.

[0057] In step (3), the means of separating the cleaning agent composition from the dirt consists of one or more separation means selected from gravity separators, coalescers, centrifuges, filter membranes and adsorption towers, other than distillation.

[0058] The above separation methods are selected based on the droplet size of the dirt phase and / or the difference in specific gravity with the cleaning agent composition, as well as the required cleanliness and recirculation rate of the cleaning agent composition. Two or more methods can also be combined.

[0059] When the droplet size of the fouling phase is large, an oil-water separator with low equipment cost and easy management is preferred. However, due to its slow separation speed and time consumption, centrifuges and membrane filters are preferred for separation. Alternatively, a coalescer can be used to increase the droplet size and accelerate the separation speed.

[0060] As long as a centrifuge can perform liquid-liquid separation, there are no particular restrictions on the use of conventional centrifuges such as batch or continuous centrifuges. Continuous centrifuges that can increase throughput and are easy to automate are preferred, and conventional centrifuges such as disc or cylindrical centrifuges can be used.

[0061] Generally, the higher the centrifugal acceleration, the better the separation of the centrifuge from the dirt and the faster the processing speed. However, as long as the centrifugal acceleration is approximately 400G or above, and the product of centrifugal acceleration (G) × processing time (minutes) is approximately 2000 or above, good separation can be achieved.

[0062] Most oily processing oils have a specific gravity of approximately 0.95 or less, while the cleaning agent composition of the present invention has a specific gravity of approximately 1.0. Due to the difference in specific gravity, they can be separated rapidly under the above conditions. However, when the specific gravity of the dirt and the cleaning agent are similar, it may be necessary to increase the centrifugal acceleration, centrifugation time, etc. for separation.

[0063] Filter membranes can also be used as a separation method. Preferably, filter membranes with solvent resistance and a pore size of less than 0.5 μm are used. Membranes made of polypropylene, polyamide, Teflon (registered trademark), ceramic, or SUS are preferred due to their durability against most solvents.

[0064] In addition, hollow fiber membranes have a large membrane surface area per unit volume, and can be used for a long time by taking measures to deal with pore blockage based on cross-flow and reverse cleaning, so they are preferred.

[0065] The pore size of the filter membrane is generally preferably that of microfiltration membranes (MF membranes) or ultrafiltration membranes (UF membranes). The smaller the pore size, the better the separation of cleaning agent and dirt, but the filtration speed is reduced. Therefore, a pore size of approximately 0.01 μm to 0.2 μm is more preferred.

[0066] Depending on the type of dirt, it may also include filters to remove solid foreign matter, ion exchange resins to remove ionic dirt, and activated carbon to remove trace amounts of dissolved dirt.

[0067] There are no particular limitations on the composition of other cleaning systems such as cleaning and drying. For example, ultrasonic cleaning, jet cleaning, immersion cleaning, shaking cleaning, rotary cleaning, spray cleaning, and depressurized ultrasonic cleaning can be used. Depending on the required level of cleanliness and the time required, these methods can be used individually or in combination.

[0068] Example

[0069] The present invention will be further described in detail below with reference to embodiments, but the present invention is not limited to these embodiments. In addition, unless otherwise specified, "%" and "parts" refer to "capacity %" and "capacity parts".

[0070] Examples 1-28, Comparative Examples 1-7

[0071] Various cleaning agent compositions were prepared, and their cloud point was determined, cleaning properties were evaluated, and separation properties were evaluated.

[0072] The composition and results of the cleaning agent compositions used in the tests are shown in Tables 1 and 2. Additionally, the solvents used in the cleaning agent compositions are described below.

[0073] (Water-insoluble solvent)

[0074] BuL Butyl Lactate

[0075] DAP diacetoxypropane

[0076] DEBM diethylene glycol n-butyl methyl ether

[0077] DEDG diethylene glycol diethyl ether

[0078] DEHe Diethylene glycol hexyl ether

[0079] DEMiP Diethylene Glycol Methyl Isopropyl Ether

[0080] DEMnP diethylene glycol methyl n-propyl ether

[0081] DPDM dipropylene glycol dimethyl ether

[0082] DPP dipropylene glycol monopropyl ether

[0083] PGB Propylene Glycol n-Butyl Ether

[0084] (Water-soluble solvent)

[0085] DAA diacetone alcohol

[0086] DPM dipropylene glycol monomethyl ether

[0087] MMB 3-methoxy-3-methylbutanol

[0088] PGPR Propylene glycol n-propyl ether.

[0089] [Table 1]

[0090]

[0091] [Table 2]

[0092]

[0093] [Determination of cloud point]

[0094] Place the cleaning agent composition into a 30ml glass container, heat with warm water at 80°C, or cool with cold water at 5°C, and visually observe the appearance of the cleaning agent composition. The temperature at which the cleaning agent composition begins to turn cloudy is taken as the cloud point.

[0095] [Evaluation of Cleanability]

[0096] An M4×20mm bolt with a nut was coated with an oil-based processing oil (FBH-9S, manufactured by Nippon Oil Co., Ltd.). The bolt was then immersed in 100ml of a cleaning agent composition maintained at a specified temperature (10°C~15°C above its cloud point) and ultrasonically cleaned for 3 minutes (40kHz 200W). Next, it was rinsed for 1 second in the same cleaning agent composition, air-dried, and then dried with hot air. The amount of residual oil was determined by oil content analysis after drying, and the cleaning performance was evaluated according to the following criteria.

[0097] Evaluation criteria (residual oil content of the item being cleaned)

[0098] ◎: Less than 0.01 (mg / piece)

[0099] ○: 0.01 or higher and less than 0.02

[0100] △: 0.02 or higher and less than 0.03

[0101] ×: 0.03% or more,

[0102] -: No evaluation was conducted.

[0103] [Evaluation of Separability]

[0104] To 150 parts by volume of the cleaning agent composition (solvent component only), 0.6 parts by weight of an oily processing oil (manufactured by Nippon Working Oil Co., Ltd., FBH-9S) equivalent to approximately 4000 ppm of dirt was added and dissolved. The mixture was heated to 70°C and then mixed with 350 parts by volume of deionized water at 70°C and stirred for 10 minutes. The mixture was then cooled to below 30°C, and the dirt was separated under the conditions described in (1), (2), and (3) below. The non-volatile components of the separated cleaning agent composition were determined by gravimetric analysis, and the separation performance was evaluated according to the evaluation criteria described below. In case (1), the time to obtain 100 ml of filtrate was also measured.

[0105] Separation conditions:

[0106] (1) Separation using hollow fiber membranes

[0107] Hollow fiber membrane: MF membrane: Asahi Kasei Corporation Microza USP-043 (nominal pore size 0.1μm),

[0108] Asahi Kasei Corporation's Microza UMP-053 (nominal pore size 0.2μm)

[0109] UNITIKA LTD. MFW040-2 (nominal pore size 0.04μm),

[0110] UNITIKA LTD. MFW100-2 (nominal pore size 0.1μm),

[0111] UF membrane: manufactured by UNITIKA LTD., UF30 (nominal molecular weight cutoff 30000),

[0112] Hollow fiber pressure: 0.05~0.06MPa

[0113] Filtration rate determination: The time required to obtain 100 ml of filtrate was measured.

[0114] (2) Separation using a centrifuge

[0115] Centrifuge: AS ONE CN-1050 centrifuge (angle rotor RA-5004),

[0116] Centrifugation time: 5~30 minutes

[0117] Rotation speed: 2000~5000rpm (maximum centrifugal acceleration 420G~2620G).

[0118] (3) Separation using ceramic membranes

[0119] Ceramic membrane: Cefilt MF0.1 (nominal pore size 0.1 μm) manufactured by NGK FILTECH, LTD.

[0120] Filtration pressure: 0.10~0.15MPa

[0121] Evaluation criteria (non-volatile components of the cleaning agent composition)

[0122] ◎: Less than 100 ppm

[0123] ○: 100ppm or higher but less than 300ppm

[0124] △: Above 300ppm and below 500ppm

[0125] ×: 500ppm or more,

[0126] -: No evaluation was conducted.

[0127] Evaluation Criteria (Filtration Rate of Hollow Fiber Membrane)

[0128] ◎: Less than 15 minutes

[0129] ○: 15 minutes or more but less than 30 minutes

[0130] ×: More than 30 minutes

[0131] -: No evaluation was conducted.

[0132] The present invention has been described in detail with reference to specific embodiments, but it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the essence and scope of the present invention.

[0133] It should be noted that the entire contents of the specification, claims and abstract of Japanese Patent Application No. 2023-187592, filed on November 1, 2023, are incorporated herein as disclosure of the specification of this invention.

Claims

1. A cleaning agent composition comprising a water-insoluble solvent and water, wherein the water content is in the range of 60% to less than 90% by volume, and exhibits a cloud point of 20°C to 70°C.

2. The cleaning agent composition according to claim 1, wherein, A water-insoluble solvent is a solvent that is more than 1g / 100g of water and does not dissolve in water in any proportion at 70°C.

3. The cleaning agent composition according to claim 1, wherein, The water-insoluble solvent is one or more selected from the group consisting of diethylene glycol methyl propyl ether, diethylene glycol methyl butyl ether, diethylene glycol diethyl ether, dipropylene glycol dimethyl ether, ethylene glycol hexyl ether, diethylene glycol hexyl ether, propylene glycol butyl ether, dipropylene glycol propyl ether, propyl lactate, and butyl lactate.

4. The cleaning agent composition according to claim 1, further comprising a water-soluble solvent.

5. The cleaning agent composition according to claim 4, wherein, Water-soluble solvents are solvents that dissolve in water in any proportion.

6. The cleaning agent composition according to claim 4, wherein, The water-soluble solvent is one or more selected from the group consisting of ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monoisobutyl ether, propylene glycol monopropyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, ethylene glycol, diethylene glycol, propylene glycol, 3-methoxy-1-butanol, 3-methoxy-3-methylbutanol, etc.; methyl lactate, ethyl lactate, tetrahydrofurfuryl alcohol, furfuryl alcohol, 2-dimethyl-1,3-dioxolane-4-methanol, γ-butyrolactone, and diacetone alcohol.

7. A recycling system for a cleaning agent composition, comprising: Step (1) involves maintaining the cleaning agent composition according to any one of claims 1 to 6 at a temperature above the cloud point and dispersing the solvent component of the cleaning agent composition in water to clean the object to be cleaned. Step (2) involves cooling the cleaned cleaning agent composition to below its cloud point to separate the dirt from the cleaning agent composition phase. Step (3) involves removing the dirt separated from the cleaning agent composition phase using separation methods other than distillation; as well as Step (4) involves reusing the cleaning agent composition that has removed dirt on a non-cleaned object in step (1).

8. The recycling system according to claim 7, wherein, In step (3), the separation means is to use at least one of the following: a specific gravity separator, a coalescer, a centrifuge, a filter membrane, and an adsorption tower.

9. The recycling system according to claim 8, wherein, The filter membrane is a hollow fiber membrane.

10. The recycling system according to claim 7, wherein, The items to be cleaned are those with non-water-soluble dirt attached to them.

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