JPH0874081A - Method for cleaning article - Google Patents

Abstract

PURPOSE: To develop a method for cleaning an article without causing ignition, without any waste rinsing water and capable of saving the energy needed to recover oil. CONSTITUTION: A mixture of org. solvent and water having the composition capable of reversibly forming a homogeneous phase and two phases by the temp. change, e.g. a cleaning agent consisting of 10-60vol.% ethylene glycol monobutyl ether and 90-60vol.% water, is used. An article deposited with oil is cleaned at a temp. where the agent forms a homogeneous phase, and then the cleaned article is rinsed with water or a liq. mixture of water and org. solvent at a temp. where the agent forms two phases. The separated org. phase contg. oil is appropriately drawn off.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cleaning oils and fats attached to metal parts and the like, fluxes attached to electronic parts and the like and oil such as fingerprints.

[0002]

2. Description of the Related Art Degreasing and cleaning of articles such as metal parts, electronic parts, and semiconductor parts is nonflammable and has no risk of ignition.
Freon-based solvents or halogen-based solvents have been used because of their excellent detergency. However, recently, due to the problem of the destruction of the global environment, surfactants, water-based detergents containing alkali as a main component, hydrocarbon-based detergents, alcohol-based solvents, or tertiary petroleum hydrocarbons can be treated with surfactants to remove water. The conversion to quasi-water-based detergents dispersed in water is progressing.

[0003]

However, in the cleaning method using the water-based cleaning agent, the cleaning agent is gradually contaminated with oil and the cleaning power decreases, so that a new cleaning agent is periodically replenished and cleaned. I have to renew my medicine. In addition, since the concentration of components such as surfactants and alkalis is high in the cleaning waste liquid after it has been used for cleaning, it is necessary to incinerate it as industrial waste liquid. is there. Furthermore, it is necessary to thoroughly rinse the object to be cleaned after cleaning, but since the rinse solution is also contaminated by the cleaning agent and oil carried in, should the rinse solution be continuously discharged to prevent redeposition of dirt? , Must be replaced regularly. Since the rinsing waste liquid has a low concentration of cleaning agents and oils but is large in amount, it requires expensive equipment such as coagulating sedimentation and activated sludge. Further, 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 semi-aqueous cleaning agent has the same problem of treating the cleaning waste liquid as the method using the aqueous cleaning agent.

[0004]

As a result of intensive studies, the present inventor has found that a mixture of a certain organic solvent and water is a uniform liquid in a specific composition in a certain temperature range. When the temperature is out of the range, the organic solvent is separated into two phases, a phase containing a large amount of organic solvent (hereinafter, abbreviated as organic phase) and a phase containing a large amount of water (hereinafter, abbreviated as aqueous phase). It was found that most of the oil was in the organic phase. Further, they have found that these organic solvents alone have a flash point, but 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 composed of a mixture of an organic solvent and water, which is mixed in a composition capable of reversibly forming a homogeneous phase and two phases by a temperature change. Washing the oily article at the temperature of formation, and then mixing the water with an organic solvent that is more water-rich than the composition of the aqueous phase when separated into two phases at the temperature at which the detergent forms two phases. A method for cleaning an article, which comprises rinsing the article with a liquid or water.

The organic solvent used in the present invention forms a two-phase with water in a region satisfying a certain temperature and composition, and is known as long as it forms a homogeneous phase with water in a region outside the region. Organic solvents can be used without any restrictions. In particular, in the present invention, it is preferable that the washing temperature is in the range of room temperature to the boiling point of water for the convenience of the washing operation, and therefore, the formation of a uniform phase and two phases with water by the temperature change within the temperature range. An organic solvent that reversibly repeats can be preferably used. Specifically, the temperature is generally 40 to 100 ° C.,
And, an organic solvent that forms a two-phase with water in the region where the composition of the organic solvent is 5 to 80% by volume, and forms a homogeneous phase with water when either the temperature or the composition of the organic solvent deviates from the above range. It can be preferably used.

Specific examples of the organic solvent that can be preferably 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, propylene glycol monoethyl acetate. 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 ether. A mixture of ethers,
A mixed solution of dipropylene glycol dimethyl ether and dipropylene glycol monomethyl ether or the like can be preferably used because it has a good degreasing property for oil components such as fats and oils, mineral oil and flux.

FIG. 1 shows a phase equilibrium diagram of ethylene glycol mono-n-butyl ether and water. In the mixture of ethylene glycol mono-n-butyl ether and water, the ethylene glycol mono-n-butyl ether is 10-57.
In the region A in the range of volume% and the temperature is 49 to 128 ° C., these two components are separated into two phases. However, in the region B where either one of the composition and the temperature is out of the above range, these two components form a homogeneous phase. Specifically, a mixture of composition M of 50% by volume of ethylene glycol mono-n-butyl ether and 50% by volume of water belongs to region B at 40 ° C. and forms a homogeneous phase. The temperature of this mixture is 70
When the temperature is raised to ℃, it enters the region A and separates into two phases. At this time, the composition of the aqueous phase becomes W and the composition of the organic phase becomes S.

The same applies to a three-component system. Figure 2
Shows the phase equilibrium diagram of the ternary system of propylene glycol monobutyl ether, dipropylene glycol monomethyl ether and water. In FIG. 2, curves 1, 2 and 3 are
It is a phase equilibrium curve at each temperature of 40 ° C., 60 ° C. and 80 ° C., a uniform phase is formed in the upper region of each phase equilibrium curve, and two phases are separated in the lower region. Here, propylene glycol monobutyl ether 40% by volume, dipropylene glycol monomethyl ether 30
The mixture of composition m of vol% and water 30 vol% 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, 60 ° C
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 forming a homogeneous phase with water, sufficiently functions as a cleaning agent, and has no flammability in the above-mentioned composition. The present inventors confirmed.

In the present invention, a cleaning agent having an organic solvent and water adjusted to a composition range capable of reversibly forming a uniform phase and a two phase by a temperature change is used as a cleaning agent. Then, the above-mentioned detergent is used for washing the article on which the oil component is attached, at a temperature at which the detergent composed of the mixture of the organic solvent and water forms a uniform phase, generally at 40 to 100 ° C. As a washing method, a known method can be adopted without any limitation.
For example, a method of immersing an article with oil content in a detergent, a method of showering or spraying an article with oil content with a detergent, and the like can be adopted. At this time, it is effective to use means such as ultrasonic cleaning, shaking, and stirring together.

The oil removed from the article dissolves in a saturating amount in the detergent, above which it forms a separate phase from the detergent.
The cleaning agent used for cleaning is sent to an oil-water separation tank, where the phase-separated oil is removed and reused for cleaning. The washing temperature is preferably as high as possible in order to improve the washing power of the oil component, and it is generally preferable to adopt the highest temperature at which a uniform phase with water is formed.

The detergent used in the present invention may contain a third component for adjusting the phase separation temperature and improving the detergency. 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 to increase the phase separation temperature. Since it can be raised, washing at 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, alkali agents such as sodium hydroxide, potassium hydroxide, sodium carbonate and sodium silicate; anticorrosive agents such as benzotriazole and tritriazole; gluconic acid and ethylenediamine Chelating agents consisting of tetraacetic acid or salts thereof; surfactants such as alkylbenzene sulfonic acid, ethylene glycol alkyl ethers; certain amines such as phenyl-β-naphthylamine, or phenol derivative di-tert-butyl-p -An antioxidant such as cresol can be mentioned, and the addition amount of these components is 0.00
It is preferably in the range of 5 to 5% by weight.

The washed article is then mixed with water or a mixture of water and an organic solvent which is richer in water than the composition of the aqueous phase when the detergent is separated into two phases at a temperature at which the cleaning agent forms two phases. So I can The rinsing liquid may be a mixed liquid of an organic solvent and water, as long as it is richer in water than the composition of the aqueous phase when the cleaning agent is separated into two phases at the rinsing temperature. May be. When the rinse liquid is richer in organic solvent than the composition of the aqueous phase when the detergent is separated into two phases at the rinse temperature, the rinse liquid itself separates into two phases at the rinse temperature. At this time, the oil component that has adhered to the article and is dissolved in the cleaning agent brought into the rinsing step is dissolved in the organic phase among the phases separated into two phases. It is easy to remove all the organic phase for removing oil from the rinse solution, but if this is done, all the separated organic phase in the rinse solution must be removed, and the rinse solution is wasted. It is not desirable because it will be used.

The composition of the rinsing liquid gradually approaches the composition of the separated aqueous phase of the cleaning agent at the rinsing temperature because the cleaning solution adhering to the article is mixed with the rinsing solution after being used for a long time. For example, referring to FIG. 1, when the cleaning agent having the composition M is used and water is used as the rinsing liquid, the cleaning agent attached to the article is heated to a temperature at which it is separated into two phases during rinsing. Therefore, the organic phase having the composition S and the aqueous phase having the composition W in FIG. 1 are separated. Since the aqueous phase of the composition W is dissolved in the rinse water, the composition of the rinse solution gradually approaches the composition W after 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 cleaning agent having the composition m is separated into the organic phase having the composition s and the aqueous phase having the composition w.
Since the aqueous phase of (1) dissolves in the rinse water, the composition of the rinse solution gradually approaches the composition w with long-term use.

Therefore, when water is used as the rinsing liquid, or when a mixed liquid of an organic solvent and water which is richer in water than the composition of the aqueous phase when the cleaning agent is separated into two phases is used, At steady state, the composition of the rinse is equal to the composition of the aqueous phase when the detergent separates into two phases.

On the other hand, of the detergents attached to the article and brought into the rinsing step, the organic phase when separated into two phases is:
It does not dissolve in the rinse solution and is phase separated. In the washing process, the oil component adhering to the article is dissolved in the detergent, but when the detergent separates into two phases in the rinsing process, the oil component is dissolved in the organic phase. Therefore, by removing the organic phase that has been phase-separated from the rinsing solution in the rinsing step, it is possible to prevent the rinsing solution from being contaminated by the oil content and to easily recover the oil content. The organic phase can be separated from the rinsing liquid by, for example, a method such as overflow utilizing a difference in specific gravity.

The organic solvent used in the present invention does not have any effect on the object to be cleaned even if it is dried while being attached to the object to be cleaned, and is easily dried and removed. No problem. Therefore, rinsing with water or a mixture of water and an organic solvent at a temperature at which the detergent forms two phases provides the same good rinsing effect as when using a large amount of water.

[0021]

As can 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 as a cleaning agent is not required. Further, according to the present invention, in the rinsing step, the organic phase containing the oil component, which is a contaminant, can be easily separated from the rinsing liquid, so that the rinsing liquid can be prevented from being contaminated by the oil component. For this reason, rinse drainage, which is a problem in water cleaning, does not occur,
There is no need to install expensive water treatment equipment. Further, there is no need for a solvent distillation recovery device which is usually used for removing oil with a hydrocarbon type cleaning agent or an alcohol type cleaning agent.

[0022]

EXAMPLES Examples will be given to specifically explain the present invention, but the present invention is not limited to these examples.

Examples and Comparative Examples Commercial machine oil was applied to an aluminum plate of 50 mm × 80 mm × 1 mm at a rate of about 100 mg / sheet, which was used as a test piece and washed with a cleaning agent having the composition shown in Table 1 and 1 L of a rinsing liquid. And rinsed. The cleaning was performed by immersing the test piece in the cleaning agent at the temperature shown in Table 1 for 2 minutes. The rinsing was performed by immersing the test piece in the rinsing liquid having the temperature shown in Table 1 for 2 minutes by rocking.
After rinsing, the test piece was pulled up, dried at 80 ° C. for 10 minutes, and the oil removal rate was evaluated by the 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 liquid 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. .

[0026]

[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 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.

[Explanation of symbols]

A: Region in which ethylene glycol mono-n-butyl ether and water are separated into two phases B: Region in which ethylene glycol mono-n-butyl ether and water form a homogeneous phase M: Mixture composition of ethylene glycol mono-n-butyl ether and water S : Organic phase composition when the mixture of composition M separates into two phases at 70 ° C W: Aqueous phase composition when the mixture of composition M separates into two phases at 70 ° C Curve 1: Phase equilibrium curve at a temperature of 40 ° C Curve 2: Phase equilibrium curve at a temperature of 60 ° C Curve 3: Phase equilibrium curve at a temperature of 80 ° C m: Mixture composition of propylene glycol mono-n-butyl ether, dipropylene glycol monomethyl ether, and water s: Mixture of composition m Phase composition when water separates into two phases at 60 ° C. w: water phase composition when a mixture of composition m separates into two phases at 60 ° C.

Claims (1)

[Claims] 1. A cleaning agent comprising a mixture of an organic solvent and water, which is mixed in a composition capable of reversibly forming a homogeneous phase and two phases by a temperature change, at a temperature at which the cleaning agent forms a homogeneous phase. Clean oily items, then
Rinsing an article, characterized by rinsing the article with a mixture of water and water with an organic solvent that is richer in water than the composition of the aqueous phase when separated into two phases at a temperature at which the detergent forms two phases. Method.