JP3375097B2 - How to wash goods - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cleaning oils and fats adhering to metal parts and the like, and fluxes and fingerprints adhering to electronic parts and the like. 2. Description of the Related Art Degreasing and cleaning of articles such as metal parts, electronic parts and semiconductor parts are nonflammable and have no danger of ignition.
For reasons such as excellent detergency, a chlorofluorocarbon-based solvent or a halogen-based solvent has been used. However, recently, due to the problem of destruction of the global environment, surfactants, aqueous detergents containing alkali as a main component, hydrocarbon detergents, alcohol solvents, or tertiary petroleum hydrocarbons have been Conversion to quasi-aqueous detergents dispersed in water is progressing. However, in a cleaning method using a water-based cleaning agent, the cleaning agent is gradually contaminated with oil and the cleaning power is reduced. And the cleaning agent has to be updated. In addition, since the concentration of components such as surfactants and alkalis is high in the washing waste liquid after use for washing, in addition to oil adhering to the object to be washed, it is necessary to incinerate it as industrial waste liquid. is there. After washing, the object to be cleaned must be sufficiently rinsed.However, since the rinsing liquid is also contaminated by the cleaning agent and oil, carry out the rinsing liquid continuously to prevent reattachment of the dirt. , Must be replaced regularly. Rinsing waste liquid has a low concentration of detergent and oil content but a large amount, so expensive equipment such as coagulated sedimentation and activated sludge is required. Both hydrocarbon-based cleaning agents and alcohol-based cleaning agents are flammable solvents, have high flammability, and have a risk of ignition. Further, the cleaning method using the quasi-aqueous cleaning agent has a problem of treating the cleaning waste liquid as in the method using the aqueous cleaning agent. The present inventors have made intensive studies and as a result, have found that a mixture of a certain organic solvent and water is a uniform liquid in a specific composition and in a certain temperature range. However, when the temperature is out of the temperature range, a phase containing a large amount of organic solvent (hereinafter abbreviated as an organic phase) and a phase containing a large amount of water (hereinafter abbreviated as an aqueous phase) are separated into two phases. Among them, we found that most of the oil was in the organic phase. These organic solvents alone have a flash point, but they have found that they do not have a flash point when they form a homogeneous phase with water, and have completed the present invention. That is, the present invention uses a cleaning agent comprising a mixture of an organic solvent and water mixed with a composition capable of reversibly forming a homogeneous phase and two phases by a change in temperature. washing the adhered article of oil in the formation temperature, then at a temperature at which the detergent to form a two-phase, or a water-richer than the composition of the aqueous phase when the two phases were separated, the aqueous phase A method for cleaning an article, comprising rinsing the article with a mixture or water of an organic solvent and water having the same composition . The organic solvent used in the present invention forms a two-phase with water in a region satisfying a certain temperature and composition. However, any organic solvent that forms a uniform phase with water in a region outside the region may be used. Organic solvents can be used without any restrictions. In particular, in the present invention, the washing temperature is preferably in the range from room temperature to the boiling point of water from the viewpoint of simplicity of the washing operation. Therefore, the formation of a uniform phase and two phases with water by a temperature change within the temperature range. An organic solvent that repeats reversibly can be suitably used. Specifically, generally, a temperature of 40 to 100 ° C.,
And an organic solvent which forms a two-phase with water in a region where the composition of the organic solvent is 5 to 80% by volume, and which forms a uniform phase with water when any one of the temperature and the composition of the organic solvent is out of the above range. It can be suitably used. Specific examples of the organic solvent that can be suitably used in the present invention include, for example, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, and propylene glycol monoethyl. Alkylene glycol alkyl acetates such as ether acetate; ethylene glycol diethyl ether, ethylene glycol monobutyl ether, diethylene glycol diethyl ether, propylene glycol monoethyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol Dimethyl ether, dipropylene glycol diethyl ether, it can be mentioned alkylene glycol alkyl ethers such as tripropylene glycol monomethyl ether, etc. These may be used singly or in combination. Among these organic solvents, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol diethyl ether, a mixed solution of propylene glycol monobutyl ether and dipropylene glycol monomethyl ether, dipropylene glycol monobutyl ether and tripropylene glycol monomethyl A mixture of ethers,
A mixed solution of dipropylene glycol dimethyl ether and dipropylene glycol monomethyl ether can be suitably used because of good degreasing properties of oils such as fats and oils, mineral oils, and fluxes. FIG. 1 shows a phase equilibrium diagram of ethylene glycol mono n-butyl ether and water. In a mixture of ethylene glycol mono n-butyl ether and water, ethylene glycol mono n-butyl ether is 10 to 57%.
In the region A in the range of volume% and at a temperature of 49-128 ° C., these two components separate into two phases. However, in a region B in which one of the composition and the temperature is out of the above range, these two components form a homogeneous phase. Specifically, a mixture of a composition M of 50% by volume of ethylene glycol mono n-butyl ether and 50% by volume of water belongs to the region B at 40 ° C., and forms a homogeneous phase. The temperature of this mixture is 70
When the temperature is raised to ° C., it enters region A and separates into two phases. At this time, the composition of the aqueous phase is W, and the composition of the organic phase is S. The same applies to the case of a three-component system. FIG.
The phase equilibrium diagram of a ternary system of propylene glycol monobutyl ether, dipropylene glycol monomethyl ether and water is shown in FIG. In FIG. 2, curves 1, 2 and 3 are:
These are phase equilibrium curves at respective temperatures of 40 ° C., 60 ° C., and 80 ° C., where a homogeneous phase is formed in an upper region of each phase equilibrium curve and separated into two phases in a lower region. Here, propylene glycol monobutyl ether 40% by volume, dipropylene glycol monomethyl ether 30
A mixture having a composition m of 30% by volume and 30% by volume of water belongs to the upper region of the phase equilibrium curve 1 at 40 ° C., and forms a homogeneous phase at 40 ° C. When this mixture is heated to 60 ° C.,
And enters into the lower region of the phase equilibrium curve 2 and separates into two phases.
At this time, the composition of the aqueous phase is w and the composition of the organic phase is s. The above-mentioned organic solvent has a good degreasing property even when it forms a homogeneous phase with water, functions sufficiently as a detergent, and has no flammability in the above-mentioned composition. Have been confirmed by the present inventors. In the present invention, an organic solvent and water that have been adjusted to a composition range in which a uniform phase and two phases can be reversibly formed by a change in temperature are used as a cleaning agent. Then, at a temperature at which a cleaning agent composed of a mixture of an organic solvent and water forms a uniform phase, generally at 40 to 100 ° C., the above-mentioned cleaning agent is used for cleaning articles to which oil has adhered. As a washing method, a known method can be adopted without any limitation.
For example, a method of immersing an article with oil attached to the detergent, a method of showering or spraying the detergent on the article with oil attached, and the like can be adopted. At this time, it is effective to use means such as ultrasonic cleaning, rocking, and stirring together. The oil removed from the article dissolves in a saturating amount in the cleaning agent, above which it forms a separate phase from the cleaning agent.
The cleaning agent used for washing is sent to an oil / water separation tank, where the phase separated oil is removed and reused for washing. The washing temperature is preferably as high as possible in order to improve the washing power of the oil, and it is generally preferable to employ the highest temperature at which a uniform phase with water is formed. A third component can be added to the cleaning agent used in the present invention for adjusting the phase separation temperature and improving the cleaning power. For example, by adding lower alcohols such as ethanol, methanol and IPA; polyhydric alcohols such as ethylene glycol, ethylene glycol methyl ether and ethylene glycol ethyl ether; and esters such as methyl acetate and ethyl acetate, the phase separation temperature can be increased. Since it can be raised, cleaning at a high temperature becomes possible. The addition amount of these third components is preferably in the range of 0.1 to 10% by volume. As the third component for improving the detergency, alkaline agents such as sodium hydroxide, potassium hydroxide, sodium carbonate and sodium silicate; anticorrosive agents such as benzotriazole and tritriazole; gluconic acid, ethylenediamine A chelating agent comprising tetraacetic acid or a salt thereof; a surfactant such as an alkylbenzenesulfonic acid or an ethylene glycol alkyl ether; a certain amine such as phenyl-β-naphthylamine, or di-tert-butyl-p which is a phenol derivative; -Antioxidants such as cresol can be mentioned, and the added amount of these components is 0.00
It is preferably in the range of 5 to 5% by weight. After washing, the article is then mixed at a temperature at which the detergent forms two phases with a mixture or water of an organic solvent and water which is richer in water than the composition of the aqueous phase when separated into two phases. Rinse off The rinsing liquid may be a mixed liquid of an organic solvent and water, as long as the composition is more water-rich than the composition of the aqueous phase when the cleaning agent separates into two phases at the rinsing temperature. You may. If the rinsing liquid is richer in organic solvent than the aqueous phase composition when the detergent separates into two phases at the rinsing temperature, the rinsing liquid itself separates into two phases at the rinsing temperature. At this time, the oil dissolved in the cleaning agent adhered to the article and brought into the rinsing step is dissolved in the organic phase among the phases separated into two phases. Although it is easy to remove the entire organic phase to remove oil from the rinse solution, this requires removal of all of the separated organic phase from the rinse solution, and waste of the rinse solution. Use is not preferred. The rinsing liquid gradually becomes closer to the composition of the separated aqueous phase of the rinsing liquid at the rinsing temperature because of the mixing of the cleaning agent adhering to the article over a long period of use. For example, referring to FIG. 1, when a cleaning agent having a composition M is used and water is used as a rinsing liquid, the cleaning agent adhering to the article is heated to a temperature at which the cleaning agent separates into two phases during rinsing. Therefore, the organic phase is separated into an organic phase having a composition S and an aqueous phase having a composition W in FIG. Since the aqueous phase of the composition W dissolves in water, which is a rinsing liquid, the composition of the rinsing liquid gradually approaches the composition W by long-term use. The same applies when a three-component cleaning agent is used. That is, as shown in FIG. 2, at the rinsing temperature, the detergent having the composition m is separated into an organic phase having the composition s and an aqueous phase having the composition w.
Since the aqueous phase is dissolved in water, which is a rinsing liquid, the composition of the rinsing liquid gradually approaches the composition w with long-term use. Therefore, when water is used as the rinsing liquid, or when a mixture of an organic solvent and water that is more water-rich than the composition of the aqueous phase when the detergent is separated into two phases is used, In a steady state, the composition of the rinsing liquid is equal to the composition of the aqueous phase when the detergent separates into two phases. On the other hand, among the cleaning agents adhered to the article and brought into the rinsing step, the organic phase separated into two phases is:
It is phase-separated without dissolving from the rinse solution. In the washing step, the oil attached to the article is dissolved in the detergent, but when the detergent is separated into two phases in the rinsing step, the oil is dissolved in the organic phase. Therefore, by removing the organic phase which is phase-separated from the rinsing liquid in the rinsing step, contamination of the rinsing liquid with oil can be prevented and the oil can be easily recovered. The separation of the organic phase from the rinsing liquid can be suitably performed, for example, by a method such as overflow utilizing a specific gravity difference, and may be performed continuously or periodically. The organic solvent used in the present invention does not affect the object to be cleaned even if it is dried while adhering to the object to be cleaned, and is easily dried and removed. No problem. Therefore, by rinsing with water or a mixture of water and an organic solvent at a temperature at which the detergent forms two phases, the same good rinsing effect as when a large amount of water is used can be obtained. As will be understood from the above description, the cleaning agent used in the present invention has no flammability and can be used safely. Therefore, according to the present invention, explosion-proof equipment such as an apparatus using a hydrocarbon-based cleaning agent or an alcohol-based cleaning agent is not required. Further, according to the present invention, in the rinsing step, the organic phase containing oil, which is a contaminant, can be easily separated from the rinsing liquid, so that contamination of the rinsing liquid with oil can be prevented. For this reason, there is no rinsing drainage that is a problem in water-based cleaning,
There is no need to install expensive water treatment facilities. Further, there is no need for a solvent distillation and recovery device which is usually used for removing oil with a hydrocarbon-based cleaning agent or an alcohol-based cleaning agent. EXAMPLES The present invention will be described in more detail with reference to Examples, but it should be understood that the present invention is by no means restricted to such specific Examples. EXAMPLES AND COMPARATIVE EXAMPLES A test piece was prepared by adhering about 100 mg / sheet of a commercially available machine oil to a 50 mm × 80 mm × 1 mm aluminum plate using a cleaning agent having a composition shown in Table 1 and 1 L of a rinsing liquid. And rinsed. The cleaning was performed by immersing the test piece in a cleaning agent at the temperature shown in Table 1 for 2 minutes. The rinsing was performed by immersing the test piece in a rinsing solution having the temperature shown in Table 1 for 2 minutes while rocking.
After rinsing, the test piece was pulled up, dried at 80 ° C. for 10 minutes, and the oil removal rate was evaluated by a gravimetric method. The results are shown in Table 1. After the above washing and rinsing were repeated for 200 test pieces, the organic phase floating on the surface of the rinsing liquid was removed by overflow. The amount of oil dissolved in the remaining rinse was analyzed by the n-hexane extraction method. The results are shown in Table 1. Further, the flash points of the cleaning agent and the rinsing liquid were measured by the Cleveland method based on the flash point test method of JIS K-2265 crude oil and petroleum products. As a result, none of them had a flash point. . [Table 1] The meanings of the abbreviations in the table are as follows. EGB: ethylene glycol monobutyl ether DEGEA: diethylene glycol monoethyl ether acetate DEGDE: diethylene glycol diethyl ether PGB: propylene glycol monobutyl ether DPGM: dipropylene glycol monomethyl ether DPGDM: dipropylene glycol dimethyl ether DPGB: dipropylene glycol monobutyl ether TPGM: tri Propylene glycol monomethyl ether IPA: isopropyl alcohol

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a phase equilibrium diagram of ethylene glycol mono n-butyl ether and water. FIG. 2 is a phase equilibrium diagram of propylene glycol mono-n-butyl ether, dipropylene glycol monomethyl ether and water. [Description of Signs] A: A region where ethylene glycol mono n-butyl ether and water separate into two phases B: A region where ethylene glycol mono n-butyl ether and water form a uniform phase M: Ethylene glycol mono n-butyl ether Water mixture composition S: organic phase composition when the mixture of composition M separates into two phases at 70 ° C. W: aqueous phase composition curve when the mixture of composition M separates into two phases at 70 ° C. 1: temperature 40 ° Phase equilibrium curve at C 2: Phase equilibrium curve at a temperature of 60 ° C. 3: Phase equilibrium curve at a temperature of 80 ° C. m: Composition s of a mixture of propylene glycol mono-n-butyl ether, dipropylene glycol monomethyl ether and water : An organic phase when the mixture having the composition m separates into two phases at 60 ° C. Composition w: An aqueous phase when the mixture having the composition m separates into two phases at 60 ° C. Success

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C23G 5/02 B08B 3/08 C11D 7/50

Claims (1)

(57) [Claim 1] A cleaning agent comprising a mixture of water and an organic solvent mixed with a composition capable of reversibly forming a homogeneous phase and a two-phase by a temperature change, Washing the oiled article at a temperature at which the agent forms a homogeneous phase;
At temperatures the detergent to form a two-phase, or a water-richer than the composition of the aqueous phase when the two phases were separated, the aqueous phase
A method for cleaning an article, comprising rinsing the article with a mixture or water of an organic solvent and water having the same composition .