JPH06170346A - Method for washing oil-stained material - Google Patents

Abstract

PURPOSE:To obtain a method for washing an oil-stained material which does not cause environmental pollution, having outstanding degreasing properties, high detergency as well as superior safety and excellent sanitary effect upon working environments. CONSTITUTION:An oil-stained object 10 is washed using a cleaning agent 1 containing N-metheyl-2pyrrolidone.. while gas is injected into a washing tank 2, oil leaves the object 10 and becomes afloat. Thus the object 10 is efficient washed using a cleaning agent 1 which has an outstanding degreasing/cleaning effect, superior safety and excellent sanitary effect upon working environments without the possibilities of contaminating environments. Consequently, a satisfactorily cleaned material can be obtained and the oil removed by washing from the object 10 is efficiently disposed of, a treating work of a waste cleaning agent is mitigated and treatment cost is reduced. N-methyl-2-pyrrolidone dissolves the oil until it is saturated, and easily discharges the oversaturated oil for easy separation as the saturation solubility of N-methyl-2-pyrrolidone is low.

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 oily deposits, and more particularly to a method for cleaning oily deposits which efficiently removes and removes oil components attached to objects to be cleaned such as metal parts.

[0002]

2. Description of the Related Art In the cutting process of precision machine parts, electric parts, etc., the friction between the work material and the cutting tool is reduced, a large amount of frictional heat generated is removed, chips are washed away, and the life of the cutting tool is shortened. Cutting oil, etc. is used for the purpose of extending the surface and smoothing the finished surface.

Therefore, although these oils adhere to the processed material, it is often impossible to obtain a product if the oils remain adhered. For this reason, in the finishing process of such parts, oil components are usually washed and removed using an organic solvent.

Conventionally, as an organic solvent used for washing and removing such oil, hydrocarbon solvents such as kerosene, benzene and xylene, chlorine solvents such as trichloroethylene and tetrachloroethylene, and freon solvents such as trichlorotrifluoroethane. It has been known. In particular, CFC-based or chlorine-based solvents, which have characteristics of high cleanability and nonflammability, are used for electronic, electrical, mechanical and other parts.

[0005]

However, among the above-mentioned conventional organic solvents, hydrocarbon solvents, especially benzene,
Since xylene and the like are highly toxic and are compounds designated as harmful substances under the Industrial Safety Law, there are problems in terms of the danger and complexity of handling these. Further, the chlorine-based or chlorofluorocarbon-based solvents have major problems in terms of safety, toxicity, environmental pollution and the like. In addition, in the cleaning process of oily deposits, it is also important to efficiently remove the removed oil from the cleaning liquid.

The present invention solves the above-mentioned problems of the prior art, is excellent in degreasing and cleaning of oils, etc., has good safety and working environment hygiene, and has no problem of environmental pollution. It is an object of the present invention to provide a method for cleaning oil-adhered substances, in which it is easy to recover the removed oil from the cleaning liquid.

[0007]

According to the method for cleaning an oil-adhered object of the present invention, an object to be cleaned having oil adhered to its surface is treated with N-methyl-
When cleaning is performed by immersing in a cleaning tank containing a cleaning agent containing 2-pyrrolidone, gas is blown into the cleaning tank to remove oil adhering to the object to be cleaned and float-separated. It is characterized in that the floating oil is separated and removed from the washing tank.

The present invention will be described in detail below.

The cleaning agent for oily deposits used in the present invention is
It contains N-methyl-2-pyrrolidone as an active ingredient, and is usually used as a mixture of N-methyl-2-pyrrolidone and water. In this case, the content of N-methyl-2-pyrrolidone is usually 40% by weight or more, preferably 5%.
0 to 85% by weight, the content of water is usually 60% by weight or less,
It is preferably in the range of 15 to 50% by weight. The content of N-methyl-2-pyrrolidone is 40% by weight.
If it is less than the above, the degreasing and cleaning effect of oil is low.

The method for cleaning oil deposits according to the present invention is such that when the oil deposits are immersed in a cleaning tank containing a cleaning agent containing such N-methyl-2-pyrrolidone for cleaning, Can be easily introduced by dispersing and introducing the gas, and by separating and floating the oil separated from the object to be cleaned by the introduction of the gas, preferably continuously outside the cleaning tank.

There is no particular limitation on the method for separating and removing the oil component floating in the washing tank, and generally, it can be easily carried out using an apparatus such as an oil skimmer apparatus or an overflow apparatus. Specifically, for example, the following method can be adopted. That is, a header capable of blowing gas is provided at the bottom of the cleaning dipping tank equipped with a temperature control function, and an appropriate blowing nozzle is attached to the header. This header and nozzle are installed in a position, the number of the
The placement position is selected. The amount of gas blown out is sufficient for both physically removing the oil that adheres to the object to be cleaned and improving the contact between the cleaning agent and the object to be cleaned and chemically removing the oil. What is achieved is.
It depends on the shape and size of the object to be cleaned and cannot be generally stated, but it is effective to increase the linear velocity of the gas ejected from the gas nozzle as much as possible. Air, nitrogen, or the like is suitable as the gas to be blown out. In the usual case, the amount of gas blown is 0.2 to 20 per liter of cleaning agent.
It is preferably in the range of normal liter (Nl) / min.

In the present invention, the object to be cleaned is immersed in such a cleaning immersion tank containing the above-mentioned cleaning agent for cleaning treatment. At that time, the cleaning treatment temperature is 20-100.
C., especially 40 to 80.degree. C. are preferred.

The oil component peeled and removed from the object to be cleaned by the immersion cleaning floats in the cleaning immersion tank, so that it is preferably continuously subjected to density difference separation. In the present invention, in the density difference separation, the bubbles are introduced by gas blowing, so that the density of the oil component attached to the bubbles is reduced, and the oil component is more easily floated. Therefore, from this point as well, it is effective in terms of levitation separation that the amount of gas blown in is large, but if the amount of gas blown in is adequate to remove oil from the object to be cleaned, it is effective in levitation separation. A sufficient amount of gas is secured.

The oil component thus floated is separated and removed by the above-mentioned oil skimmer device, overflow device, etc., and discharged to the outside of the tank. This makes it possible to prevent the floating oil from reattaching to the object to be cleaned when the immersed object to be cleaned is taken out.

At this time, the detergent used in the present invention dissolves the oil until it reaches saturation, but its saturation solubility is low. For this reason, the oil that becomes supersaturated and is discharged can be easily separated from the cleaning liquid.

In other organic detergent systems, energy is required to separate the once dissolved oil and the detergent, and density difference separation is impossible. On the other hand, with water-based cleaning agents, density difference separation is possible, but after cleaning, there is a problem of rusting of the object to be cleaned and a problem of corrosion of the cleaning liquid (water), and the effect of removing adhered oil is also sufficient It is not industrially disadvantageous because it is not.

The method for cleaning oily deposits of the present invention as described above can be easily carried out by an apparatus for cleaning oily deposits as shown in FIG.

FIG. 1 is a sectional view showing a cleaning apparatus suitable for carrying out the method for cleaning oily deposits of the present invention.

The cleaning apparatus shown in the drawing has a cleaning tank 2 for containing the cleaning liquid 1, a net cage 3 for suspending the object to be cleaned 10, a heat medium inlet 4A for adjusting the temperature of the cleaning tank 2, and A jacket 4 having a discharge port 4B, a spray header 5 provided with a spray nozzle 5A at the lower part of the cleaning tank 2 for gas such as air or nitrogen, and an oil skimmer device for separating and collecting floating oil in the cleaning liquid 1. 6 and the oil recovery tank 7 are mainly configured.

In order to clean the object to be cleaned 10 using the apparatus shown in the figure, the object to be cleaned 10 having oil on its surface is put in the net cage 3 and lowered, and the N-methyl- 2-
Immerse in the cleaning liquid 1 containing pyrrolidone. Then, air or nitrogen gas is blown from the lower part of the tank through the spray header 5 by the spray nozzle 5A to be dispersed, and the adhered oil component is peeled off so that the gas dispersion flow hits the object to be cleaned 10.

The oil 8 separated from the object to be cleaned 10 and floated above the cleaning liquid 1 is separated by the oil skimmer device 6 together with some cleaning liquid, and is recovered in the oil recovery tank 7. The recovered oil liquid 9A and the recovered cleaning liquid 9B recovered in the oil recovery tank 7 are treated according to a conventional method and reused as necessary. The recovered cleaning liquid 9B can be returned to the cleaning tank 3 as it is.

After the oil is removed in this way, the article to be cleaned 10 is pulled up. And if necessary,
Wash with water and dry.

Since the oil 8 is floated and removed from the cleaning liquid 10, it can be used for a large number of batch cleanings over a long period of time.

The cleaning method using the illustrated apparatus is an embodiment of the present invention, and the present invention is not limited to the illustrated method as long as the gist thereof is not exceeded. For example, at the time of cleaning, fine ones are put in a net basket as shown in the drawing, and large ones can be directly washed without putting them in the net basket. Further, even in the immersion method, it is also possible to provide a fixing metal fitting inside the cleaning tank and fix the object to be cleaned to the cleaning. Further, as for the separation and removal method of the floating oil component, an oil skimmer device, an overflow method, and others can be adopted, and the heating method of the cleaning tank can be a steam method in addition to the heat medium method shown in the drawing. Various types such as a direct heating method can be adopted.

In such a method of the present invention, the object to be cleaned to which the oil content adheres is an electronic part, an electrical part, a precision machine part, a resin machined part, a precision part such as an optical part, a machine part. , Automobile parts and jigs and tools used in the assembly process thereof. Specifically, examples of electronic components include printed wiring boards, IC lead frames, capacitors, liquid crystal displays, and semiconductor materials. As electric parts, parts such as coater cores,
Examples thereof include electric motor parts such as magnets, brushes, and housings. Examples of precision machine parts include bearings, sewing machine parts, and processing parts. As an optical component,
Examples include lenses. Mechanical parts include bearings, gears,
Examples include various mechanical parts. Examples of automobile parts include engine parts, transmission gears, and carburetors. Further, as jigs and tools used in the assembling process of such parts, the above precision parts are manufactured, molded,
Examples include jigs and tools that are handled in various processes such as processing, assembly, and finishing.

Examples of the oil adhering to these objects to be cleaned include fats, oils, machine oils, cutting oils, greases and the like.

[0027]

FUNCTION N-methyl-2-pyrrolidone is an excellent cleaning agent that is excellent in degreasing and cleaning of oils and the like, has good safety and good working environment hygiene, and has no environmental pollution.

When dipping and cleaning the object to be cleaned with such a cleaning agent, the adhering oil component can be efficiently peeled and removed by blowing gas into the cleaning tank.

Thus, the peeled oil is efficiently floated in the cleaning liquid together with the bubbles of the blown gas, and the density difference can be easily separated.

This is N- which is used as a cleaning agent in the present invention.
It utilizes the unique characteristics of methyl-2-pyrrolidone, which is an organic solvent, infinitely soluble in water, peels oil, and floats without being dissolved. That is, as described above, N-methyl-2-pyrrolidone dissolves oil until it becomes saturated, but its saturated solubility is low, and therefore supersaturated oil can be easily discharged and separated.

In the present invention, the characteristics peculiar to N-methyl-2-pyrrolidone are utilized, and by adopting a combination of the gas blowing immersion cleaning method, the oil content can be removed from the oil-adhered object to be cleaned in a short time. It is possible to easily and efficiently wash and remove the oil, and also to easily remove the oil component from the wash liquid.

According to the present invention, the oil component can be removed in a cleaning time substantially the same as in the case of using the conventional trichloroethane-based cleaning agent, and the oil component can be easily floated and separated. Is also easy. By the way, in the case of a trichloroethane-based detergent, it is industrially disadvantageous because a complicated treatment such as an oil recovery treatment of the entire amount of the washing waste liquid or periodic replacement of the washing liquid is required.

[0033]

[Examples] Specific examples and comparative examples are given below,
The present invention will be described in more detail.

Examples 1 to 4 Test pieces of the materials shown in Table 1 (2.98 cm × 4.9)
20 pieces (8 cm × 0.3 cm thickness) were randomly placed in a wire netting basket, immersed in cutting oil, and then pulled up.

In the cleaning tank of the apparatus shown in FIG. 1 containing a cleaning agent having a composition shown in Table 1 consisting of a mixture of N-methyl-2-pyrrolidone (NMP) and water, each of the above 20 test pieces together with the basket was placed. Was soaked. The liquid temperature of this cleaning tank is 70 ° C. After soaking for the time shown in Table 1, the test piece was taken out together with the basket. During the immersion cleaning, air was blown at a rate of 0.63 Nl / min per liter of the cleaning agent, and the floating oil component was separated and collected by an oil skimmer device. After this test piece was washed with water and dried, the residual state of oil on the surface was visually observed and evaluated.

Also, attach a cellophane tape to the test piece,
The adhesion was examined and the presence or absence of stains when the surface of the test piece was rubbed with a white cloth was examined. The results are shown in Table 1.

Comparative Examples 1 to 4 Test pieces were washed in the same manner as in Examples 1 to 4 except that air was not blown in.
The evaluation results of the cleaning effect are shown in Table 1.

Comparative Example 5 The test piece was washed in the same manner as in Example 3 except that 1,1,1-trichloroethane was used as the cleaning agent, and the evaluation results of the cleaning effect are shown in Table 1.

[0039]

[Table 1]

From Table 1, it is clear that the method of the present invention can efficiently remove the adhered oil component by washing in a short time. Such an effect of the present invention is an effect obtained by adopting a specific cleaning agent and a cleaning method. When the cleaning method is the same but the cleaning agent is different (Comparative Example 5).
Alternatively, even if the cleaning agents are the same, but the cleaning methods are different (Comparative Examples 1 to 4), such excellent effects cannot be obtained.

[0041]

As described above in detail, according to the method for cleaning oily deposits of the present invention, the effect of degreasing and cleaning of oil components is excellent, the safety and the working environment hygiene are good, and there is no risk of environmental pollution. By using a good cleaning agent, it is possible to efficiently wash the object to be washed with oil and obtain a good washed product, and to efficiently remove the oil that has been washed and removed from the object to be washed. It is possible to reduce the processing work of the cleaning waste liquid and the processing cost.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a cleaning device suitable for carrying out a method for cleaning oily deposits of the present invention.

[Explanation of symbols]

 1 Cleaning Liquid 2 Cleaning Tank 3 Net Basket 5 Spray Header 5A Spray Nozzle 6 Oil Skimmer Device 7 Oil Recovery Tank 10 Cleaning Object

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Tetsuo Asanuma Tetsuo Asanuma 3-chome Shiodori, Kurashiki-shi, Okayama Mitsubishi Kasei Co., Ltd. Mizushima Plant (72) Inventor Kenichi Hirota 678 Miyazaki, Fujisawa-shi, Kanagawa Nitto Chemical Industrial Co., Ltd. Fujisawa Sales Office (72) Inventor Yamada, et al. Fujisawa City, Kanagawa 678 Miyamae Nitto Chemical Industry Co., Ltd. Fujisawa Sales Office

Claims (1)

[Claims] 1. When cleaning an object to be cleaned with oil adhered to its surface by immersing it in a cleaning tank containing a cleaning agent containing N-methyl-2-pyrrolidone, a gas is blown into the cleaning tank to blow the gas. A method for cleaning an oil-adhered object, which comprises removing oil adhering to an object to be cleaned, floating and separating the oil, and then separating and removing the floating oil from the cleaning tank.