JPH1057910A - Cleaning method of article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent working environment pollution or fire due to an organic solvent by dipping an article to be cleaned in water to replace the organic solvent with water and drying after dipping and cleaning the article to be cleaned in the organic solvent. SOLUTION: Each of 1st and 2nd tanks as a dipping cleaning tank 1 houses the organic solvent such as trichloroethylene, methylene chloride and a 3rd tank is used as a dipping replacing tank 2. As water charged in the dipping replacing tank 2, a distilled water or an aq. solution obtained by adding a compound having an alcoholic hydroxy group such as ethanol, ethylene glycol in the distilled water is used for cleaning. That is, the article 9 to be cleaned is dipped in the dipping cleaning tank 1 containing the organic solvent, for example, for 3min at a room temp. to be cleaned, is rocked in the dipping replacing tank 2 for 5min to replace the organic solvent stuck to the article with water and after that, transported to a drying tank 3 to vaporize water stuck to the article to be dried by blowing a hot air of about 100 deg.C. The organic solvent replaced in the dipping replacing tank 2 is recovered in a solvent/water separation tank 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel cleaning method for cleaning contaminants such as oils and fats, metal powders and the like adhering to articles to be cleaned, and a cleaning apparatus used in the cleaning method. More specifically, the present invention provides a cleaning method and a cleaning apparatus in which the loss due to evaporation of an organic solvent during cleaning is significantly reduced.

[0002]

2. Description of the Related Art A cleaning technique using an organic solvent has been widely used for cleaning contaminants such as oils and fats and metal powders adhering to articles to be cleaned. In the case where a chlorine-based organic solvent such as trichlorethylene is used, generally, after immersion cleaning, steam cleaning with a solvent is performed to finish-clean and dry the article to be cleaned.

FIG. 2 shows a cleaning apparatus for performing the above-described steam cleaning, in which an immersion cleaning tank 21 has a heater 23 therein.
Are provided in series, a common gas phase portion of these cleaning tanks is cooled by a condenser 24, and a hood 25 to which an exhaust duct 26 for bleeding is connected.
Is provided.

In the case of using petroleum solvents such as normal alkanes and cycloalkanes, after immersion cleaning, the solvent adhered is forcibly dried by heating and / or blowing instead of steam cleaning.

[0005]

However, these cleaning techniques using an organic solvent have a problem in the treatment of the vapor of the organic solvent generated during the cleaning step, particularly during drying.

If a chlorine-based organic solvent is used, after the cleaning is completed, in the steam cleaning with saturated vapor of the organic solvent performed as a means for evaporating and drying the organic solvent adhering to the article to be cleaned, the vapor is removed from the outside of the apparatus. Environmental pollution due to leakage to the public. In order to prevent such leakage, as shown in FIG. 2 described above, measures have been taken to extract atmospheric gas generated in steam cleaning from an exhaust duct and treat it with activated carbon or the like. In addition, there is a problem that a large-sized processing facility is required.

When a flammable organic solvent such as a petroleum-based solvent is used as a cleaning liquid, there is a risk of fire due to flammable gas generated in a drying step after cleaning.

[0008] Therefore, when using the washing equipment, necessary fire-prevention measures are taken in the washing equipment and the installation place, and when drying the article to be washed, a large amount of air is required in the drying tank in order to keep the organic solvent concentration below the explosion limit. It is necessary to take countermeasures such as dilution with a nitrogen gas or drying under a nitrogen gas atmosphere.

[0009]

Means for Solving the Problems The present inventors have conducted intensive studies in order to develop a cleaning method which can solve the above-mentioned problems when cleaning and drying with an organic solvent. As a result, after immersion cleaning of the article to be cleaned with an organic solvent, the article to be cleaned is immersed in water, the attached organic solvent is replaced with water, and then the drying process is performed. It has been found that the danger of environmental pollution and fire can be eliminated, and the present invention has been completed.

That is, the present invention provides a method for cleaning an article, comprising immersing and cleaning the article to be cleaned with an organic solvent, and then immersing the article to be cleaned in water to replace the organic solvent adhering with water. is there.

The present invention also provides an apparatus for use in carrying out the above method, comprising an immersion cleaning tank using an organic solvent as a cleaning liquid, followed by an immersion replacement tank using water as a replacement medium in series. The present invention also provides a cleaning apparatus characterized in that after cleaning a cleaning article in an immersion cleaning tank, the organic solvent adhering in the immersion replacement tank is replaced with water.

In the present invention, the organic solvent used as the cleaning liquid is not particularly limited as long as it is generally used for cleaning contaminants such as oils and fats and metal powder. For example, chlorinated organic solvents such as trichloroethylene and methylene chloride, and petroleum solvents such as normal alkanes and cycloalkanes can be suitably used.

In the immersion cleaning using the organic solvent, known conditions and means are employed without any particular limitation. For example, the temperature of the organic solvent in the immersion cleaning is a temperature equal to or lower than the boiling point of the organic solvent, preferably one point lower than the flash point of the organic solvent.
It is desirable to set the temperature to about 0 ° C. lower. Also, the immersion cleaning may be performed in one step, but preferably 2 to 5 times.
This is performed by a so-called multi-stage method in which immersion cleaning of the stages is repeated.

When the immersion cleaning is performed in multiple stages, it is preferable to set the cleanliness of the organic solvent as the cleaning liquid gradually higher as the object to be cleaned moves to the later stage in order to efficiently perform the cleaning. . In particular, it is desirable to set the contaminant concentration in the final stage to be 100 ppm or less. Further, it is preferable to set the temperature of the cleaning liquid so that the temperature of the cleaning liquid gradually increases within the above-mentioned temperature range as the article to be cleaned shifts to the subsequent stage, in order to improve the cleaning property.

Further, in the immersion cleaning described above, it is desirable to use at least one stage of cleaning together with known cleaning auxiliary means such as ultrasonic irradiation and oscillating rotation.

In the present invention, it is important to carry out an operation of replacing the organic solvent adhering to the article to be cleaned with water after immersion cleaning with the above organic solvent in order to achieve the object of the present invention. That is, by replacing the organic solvent adhering to the article to be cleaned with water, the generation of vapor of the organic solvent in the subsequent drying can be extremely suppressed, and as a result, exhaust gas treatment equipment and fire prevention measures are substantially reduced. Is unnecessary.

In the above-mentioned operation of replacing the organic solvent adhering to the article to be washed with water, in order to carry out this efficiently,
With the article to be cleaned immersed in water, ultrasonic irradiation, rocking,
It is desirable to apply means such as rotation.

The water used for the replacement is not particularly limited as long as it has a degree of cleanliness that does not contaminate the article to be cleaned which has been cleaned by immersion cleaning with an organic solvent.
Normal tap water, well water and the like can also be used. However, when cleanliness is particularly required, it is desirable to use purified water such as distilled water or ion-exchanged water.

The above-mentioned water contains 0.1 to 50% by weight, preferably 0.5 to 20% by weight, of a compound having an alcohol type hydroxyl group having both hydrophilicity and hydrophobicity.
Is preferable because the replacement with water and the organic solvent is facilitated. The above operation is particularly effective when the organic solvent is hardly soluble in water, such as a chlorine-based solvent or a petroleum-based solvent.

Typical examples of such a compound having an alcohol-type hydroxyl group include ethanol,
Alcohols such as ethylene glycol and propylene glycol, ethylene glycol-monobutyl ether,
Glycol alkyl ethers such as propylene glycol-monomethyl ether, so-called alkyl or alkylphenyl ether type nonionic surfactants such as polyoxyethylene nonylphenyl ether and polyoxyethylene lauryl ether And so on. Further, a known rust preventive component such as an amine can be added to the above-mentioned water in order to prevent rusting during washing and drying of the article to be washed.

By repeatedly performing the above-mentioned substitution operation with the organic solvent, the organic solvent gradually accumulates in the water.
Therefore, water contaminated by organic solvents is continuously
Alternatively, it is desirable that the concentration of the organic solvent is maintained at a certain level or less, generally 5% by volume or less by intermittent purification treatment or supply of fresh water.

In the method of the purification treatment, a known means for separating an organic solvent and water is employed without any particular limitation. For example,
In the case of trichlorethylene or normal alkane, which is hardly soluble in water, phase separation occurs with water, so that it can be easily separated due to a difference in specific gravity. In the case of a soluble organic solvent, separation by distillation is preferred. In the present invention, the article to be cleaned, in which the attached organic solvent is replaced by water, may be dried by natural drying, but it is preferable to forcibly dry the article by heating and / or blowing. As the heating temperature, a temperature that does not adversely affect the article to be cleaned is selected and employed within a range of 40 to 200 ° C.

The present invention also provides a cleaning apparatus capable of suitably performing the above-described cleaning method.

FIG. 1 is a schematic view showing a typical embodiment of the cleaning apparatus of the present invention. As shown in FIG. 1, the cleaning apparatus of the present invention comprises an immersion cleaning tank 1 using an organic solvent as a cleaning liquid, followed by an immersion replacement tank 2 using water as a replacement medium, and immersing an article 9 to be cleaned. After washing in the washing tank 1, the organic solvent adhering in the immersion displacement tank 2 is replaced with water.

The above immersion washing tank 1 is, as shown in FIG.
It is preferable to configure it in multiple stages of two or more tanks. In this case,
It is desirable to maintain the cleanliness of the final stage high by replenishing the organic solvent as the cleaning solution with a new solution from the final stage side of the immersion cleaning tank and sequentially sending the solution by means such as overflow.

The immersion displacement tank 2 is usually constituted by one tank, but two or more tanks may be provided in series as needed.

In the cleaning apparatus of the present invention, the immersion displacement tank 2
Then, it is desirable to provide an organic solvent / water separation device 6 for purifying water contaminated by replacement with an organic solvent, and to purify the water. The purified water can be circulated again through the line 8 to the immersion displacement tank 2, and the separated organic solvent is
It is desirable to circulate through at least one of the immersion washing tanks 1 by the line 7.

The organic solvent / water separator 6 is preferably a separator which separates the organic solvent using an organic solvent when the organic solvent is hardly soluble in water such as a chlorine-based solvent or a petroleum-based solvent. is there. The recovered organic solvent can be used again as it is or after purification.

When the organic solvent is soluble in water, a purification device such as a still can be used as the organic solvent / water separator 6.

Of course, it is also possible to exchange the entire amount of water periodically.

The means for moving the article 9 to be cleaned in the immersion cleaning tank 1 and the immersion replacement tank 2 is not particularly limited.
For example, the articles 9 to be cleaned can be sequentially moved manually from the top of the above-mentioned cleaning apparatus. However, in an industrial implementation, a ceiling crane or a chain as shown in FIG.
The automation by the contact type transport device 4 is preferably adopted.

In the cleaning apparatus of the present invention, the article to be cleaned 9
Is subjected to immersion cleaning in an immersion cleaning tank using an organic solvent as a cleaning liquid, and then the attached organic solvent is replaced with water in the immersion replacement tank 2 using water as a replacement medium by the moving means 4 or the like and taken out.

In the apparatus of the present invention, the article 9 to be cleaned taken out of the immersion displacement tank 2 is provided with a drying tank 3 if necessary, and the attached water is dried and removed, and taken out of the apparatus.

It should be noted that water is relatively difficult to dry, especially when the article to be cleaned is easily rusted. If it takes a long time to remove the water, rusting may occur. It is desirable to provide a decompression means or the like alone or in combination, and to dry quickly.

[0035]

As described above, according to the cleaning method of the present invention, since the organic solvent that pollutes the environment or has a risk of fire is replaced by water during drying, the organic solvent is directly Solvent vapor during drying can be substantially eliminated as compared with the conventional method in which drying is performed.

Therefore, according to the cleaning method or apparatus of the present invention, measures against environmental pollution by the organic solvent are reduced as compared with the conventional method and apparatus, and when the organic solvent is flammable,
The risk of fire during drying is eliminated.

On the other hand, as for the cleaning effect, the same effect as the conventional method can be obtained because the cleaning itself is performed by the organic solvent.

[0038]

EXAMPLES The present invention will be described in more detail with reference to Examples, but it should not be construed that the invention is limited thereto.

Examples 1 to 7 The object to be cleaned was cleaned using the cleaning apparatus shown in FIG.

In the immersion tank shown in the figure, the organic solvents shown in Table 1 were put into the first and second tanks to form an immersion washing tank 1, and the third tank was set as an immersion replacement tank 2. As shown in Table 1, distilled water (Nos. 1 to 4) or an aqueous solution (Nos. 5 to 7) obtained by adding the compounds shown in Table 1 to distilled water was used as the water to be put into the immersion displacement tank 2. Carried out.

A 20 cm square polished iron plate was prepared as an object to be cleaned, and a press oil was applied to the polished iron plate.

In a immersion washing tank 1 containing an organic solvent, at room temperature,
The article to be cleaned 9 was sequentially immersed and washed for 3 minutes, and finally rocked in the immersion displacement tank 2 for 5 minutes to replace the attached organic solvent with water.

At this time, the time required for roughly removing the solvent was visually measured.

Thereafter, the article to be cleaned is transferred to the drying tank 3 and
The attached water is evaporated and dried by blowing hot air of 00 ° C,
The washability of the article to be washed was visually observed.

On the other hand, the average concentration of the organic solvent in the exhaust gas when the gas phase of the cleaning device was bleed from the hood and exhausted from the exhaust duct was measured.

The concentration of the chlorine-based solvent was measured by a gas chromatograph, and the concentration of the non-chlorine-based solvent was measured by a combustion gas analyzer.

The organic solvent substituted in the immersion displacement tank 2 floats or sinks on the water surface due to a difference in specific gravity from water when the organic solvent is hardly soluble in water. In the case of floating, an overflow circuit is formed between the immersion displacement tank 2 and the solvent / water separation tank 6, and the organic solvent which floats on the surface of the immersion displacement tank is removed by overflow, and the solvent / water is removed. The organic solvent separated into the upper layer in the separation tank was recovered, and the amount was measured. In case of sedimentation, the solvent / water separation tank is taken out from the bottom of the immersion displacement tank, and
The organic solvent separated into a lower layer in the water separation tank was recovered.

The experiment was repeated five times, and the average value was shown.

Comparative Example 1 As Comparative Example 1, washing and drying were performed in the same manner as in Example 1 except that the organic solvent was not replaced by water with a petroleum solvent.

The concentration of the solvent in the exhaust gas at that time was determined in Example 1.
Table 1 (Nos. 8 to 9) shows the results measured in the same manner as described above. The experiment was repeated five times, and the average value was shown.

Comparative Example 2 As a comparative example 2, an object to be cleaned was subjected to immersion cleaning and steam cleaning with a chlorine-based solvent using the cleaning apparatus shown in FIG. As a method, the same article to be washed was used, and the article to be washed was immersed and washed in the immersion washing tank 21 containing an organic solvent at room temperature for 3 minutes at a room temperature, and finally steam-washed in a steam washing tank 22 for 3 minutes. It was taken out in a dry state.

The concentration of the solvent in the exhaust gas at that time was determined in Example 1.
Table 1 (Nos. 10 to 11) also shows the results measured in the same manner as in the above.

The experiment was repeated five times, and the average value was shown.

[0054]

[Table 1]

[Brief description of the drawings]

FIG. 1 is a schematic view of a representative embodiment of the cleaning apparatus of the present invention.

FIG. 2 is a schematic view of a typical embodiment of a conventional immersion-steam cleaning apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Immersion washing tank 2 Immersion replacement tank 3 Drying tank 4 Conveying device of article to be washed 5 Hot air blowing nozzle 6 Solvent / water separator 7 Solvent return line 8 Water return line 9 Object to be washed 10 Food 11 Exhaust duct 21 Immersion washing Tank 22 Steam cleaning tank 23 Heater 24 Condenser 25 hood 26 Exhaust duct

Claims (4)

[Claims] 1. A method for cleaning an article, wherein the article to be cleaned is immersed and washed in an organic solvent, and the organic solvent adhered by immersing the article in water is replaced with water. 2. The method for cleaning an article according to claim 1, wherein the water for immersing the article to be cleaned contains 0.5 to 50% by weight of a compound having an alcohol type hydroxyl group. 3. An immersion cleaning tank using an organic solvent as a cleaning liquid, followed by an immersion replacement tank using water as a replacement medium, which are arranged in series, and the article to be cleaned is washed in the immersion cleaning tank and adheres in the immersion replacement tank. A cleaning device, wherein an organic solvent is replaced with water. 4. The cleaning apparatus according to claim 3, further comprising a drying tank for drying the article to be cleaned taken out of the immersion displacement tank.