JP3315355B2 - Cleaning agent for PCB contaminants - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning agent for PCB (polychlorobiphenyl) contaminants, and more particularly, to a cleaning agent which remains in an extremely narrow space such as an aluminum foil electrode inside a capacitor or a copper coil inside a transformer. The present invention relates to a cleaning agent having excellent permeability and solubility, which is compatible with good cleaning treatment of a PCB.

[0002]

2. Description of the Related Art PCBs have been widely used in electrical products such as transformers and capacitors, and in heat media because of their excellent electrical insulation properties and thermal and chemical stability. However, the harmfulness of PCB became clear in 1973
After the year, production has been stopped, and electrical products including PCBs have been obliged to be kept, which is the current situation. Due to the storage for a long period of time, there is a concern that PCBs may leak into the environment due to corrosion and breakage of containers, and illegal dumping frequently occurs. Therefore, processing of the stored PCB is urgently required. As a method of treating PCB, there is a high-temperature combustion method, but recently, a path which can be treated by a chemical decomposition method or the like is being opened.

[0003] However, from transformers and capacitors to PCB
After extracting the container, the built-in components such as coils and electrodes are P
Since the CB is contaminated and cannot be disposed of as it is, it is necessary to clean the PCB remaining in these containers and the like. Conventionally, a cleaning agent used for cleaning PCB contaminants commercially in Europe and the United States is tetrachloroethylene (hereinafter abbreviated as PCE). In Japan, trichlorethylene or P
It is to be cleaned by CE, but at present, P
CB treatment has not been performed at all, and there is no example of cleaning PCB contaminants in Japan.
As a cleaning agent used for cleaning PCBs attached to small glassware or the like in a laboratory scale experiment, n-
Hexane is known.

[0004] PCE has excellent cleaning properties and is nonflammable. Therefore, it has been widely used not only as a cleaning agent for PCB contaminants but also for cleaning. However, the harmfulness of PCE has been revealed, and groundwater contamination has been a problem in many places, and its emission has been severely restricted by the Water Pollution Control Law. Also, PCEs are subject to specially controlled waste, and at present these cleaning agents are virtually unusable.

[0005]

SUMMARY OF THE INVENTION Conventionally used PC
Since the use of E is restricted due to its harmfulness, the disposal of electrical equipment and the like contaminated with PCB cannot be promoted unless an alternative cleaning agent is developed. PCE was a major advantage of being nonflammable. However, most of non-flammable cleaning agents are substances that cause global warming gas and ozone layer destruction because they usually contain chlorine and fluorine like fluorocarbons.

[0006] Since n-hexane does not contain chlorine or fluorine like fluorocarbons, it can be used as a clean cleaning agent for treating electrical equipment and the like contaminated with the above PCB, but has a flash point of -26. Because of the extremely low temperature of 0 ° C., the risk of ignition is large, there is a problem in handling, and there is an inconvenience limited to the processing of small-scale equipment. PCE and n
-Hexane also does not have the good permeability necessary for good cleaning of PCBs remaining in very narrow spaces, for example aluminum foil electrodes inside capacitors or copper coils inside transformers. The present invention addresses the various problems found in the above-described conventional cleaning agents, and provides a cleaning agent for PCB contaminants that is safe in terms of environment and explosive flammability and has a cleaning performance equal to or higher than that of PCE. It is intended for.

[0007]

To achieve the above object,
The cleaning agent for PCB contaminants of the present invention comprises β-oxyethyl methyl ether (CH ₂ OCH ₂ CH ₂ OH) and n-butyl acetate (CH ₃ C).
OOCH ₂ CH ₂ CH ₂ CH ₃ ) as the active ingredient. The properties required for cleaning PCB contaminants are PCB
In addition to solubility in water, permeability, recoverability, safety and economy are also mentioned.

In the present invention, in particular, an aluminum foil electrode or a copper coil member immersed in a PCB liquid in a capacitor of an electric device or a transformer, or between individual aluminum foil layers. The gap between the windings of the coil copper wire is extremely small, and when treated with a conventionally known PCB cleaning agent, it is difficult to dissolve the PCB remaining in the gap between the aluminum foil laminations and the gap between the windings of the coil copper wire. To dissolve and remove PCBs remaining in very narrow gaps of similar members, and thus, together with the solubility, in particular, the permeability that can penetrate into the extremely narrow gaps described above. Is an essential requirement.

As described above, there is a need for a cleaning agent for satisfactorily cleaning and removing PCBs remaining on members such as electric equipment, including satisfactorily dissolving and removing PCBs remaining in extremely narrow gaps. The properties are two properties of solubility and permeability, and it is optimal to use a mixture of a substance having excellent solubility and a substance having excellent permeability. Further, in order to facilitate the recovery of a reusable cleaning liquid from the used cleaning waste liquid, it is necessary that the two mixed substances are not separated during the distillation treatment in the distillation reactor. This requires that the two substances have similar boiling points to each other and be soluble in each other.

[0010] In addition to the above-mentioned washing performance such as solubility and permeability, recovery, safety and economy must be considered. Regarding the recoverability, the separation efficiency of the PCB should be high when recovering the detergent by distillation or the like, and the performance of the detergent should not be deteriorated due to repeated distillation, or even if there is little, it can be reused. Regarding safety, it is required that the safety is high for any of the human body, fire and the global environment.

As a result of various studies and considerations of the above-mentioned required characteristics, β-oxyethyl methyl ether (boiling point: 124.3) is a substance showing satisfactory solubility in PCB.
° C). As a substance having high permeability to be mixed with this, as a result of searching under the condition that the two kinds of substances mixed during distillation do not separate from each other, have excellent permeability, and the boiling point is close to β-oxyethyl methyl ether, N-Butyl acetate (boiling point 124-125 ° C) was selected. In the above, the mixture ratio of the two selected substances is β-oxyethyl methyl ether: n-butyl acetate = 90: 10 to 60:
It is preferable that the mixing ratio be in the range of 40 (capacity ratio; hereinafter omitted), and if a mixing ratio other than this is taken, there is a disadvantage that any performance is deteriorated.

Β-oxyethyl methyl ether 90%
(Volume%; the same applies hereinafter) and n-butyl acetate 10% (volume%; the same applies hereinafter).
It is higher than -26 ° C of -hexane, and is superior in fire safety to n-hexane. Further, this mixture is composed of only carbon (C), hydrogen (H), and oxygen (O), and a cleaning waste liquid after cleaning all PCB contaminants or a cleaning waste liquid that cannot be reused, It is a substance that generates only carbon dioxide gas and water vapor when incinerating the fraction obtained after separating the PCB by treating it in a distillation reactor, and has little adverse effect on the global environment.

A cleaning agent for PCB contaminants consisting of a mixture of 90% β-oxyethyl methyl ether and 10% n-butyl acetate (hereinafter abbreviated as “MCBA”) is PCE, n-butyl.
Compared to hexane, it is superior in cleaning efficiency, has less toxicity, and has less influence on the global environment, and is therefore most suitable as a cleaning agent for PCB contaminants. In addition, this detergent is not manufactured from a completely new compound, but can be easily prepared by mixing two widely-available existing substances at a predetermined mixing ratio, thereby reducing the chemical cost. There is also.

[0014]

Embodiments of the present invention will be described in more detail with reference to the drawings. FIG. 1 shows an experimental apparatus for cleaning a PCB remaining in an extremely narrow space, such as an aluminum foil electrode inside a capacitor or a copper coil inside a transformer, of an electric appliance, particularly with the cleaning agent of the present invention. In this example, the processing is performed using an autoclave. In FIG. 1, the main components of the apparatus are an autoclave 1, a cleaning agent tank 2, and a washing waste liquid tank 3,
The cleaning agent tank 2 and the washing waste liquid tank 3 are connected to the autoclave 1 via pipes 4 and 5, respectively.

In the autoclave 1, a basket 6 for storing an object to be processed is housed so as to be freely taken in and out, and a spray nozzle 7 and a cooling coil 8 are attached to an upper portion thereof. A liquid pump 9 and a heater 10 are attached to the pipe 4, and the tip is connected to the spray nozzle 7. 11 and 12 are control valves, 13 is a deaeration valve, 14 and 15 are thermometers, and 16 is a pressure gauge. Reference numerals 17 and 18 denote a cleaning agent and a cleaning waste liquid of the present invention, respectively, and 19 denotes a viewing window.

Using the above experimental apparatus, the cleaning agent 1 of the present invention was used.
7 allows the PCB-contaminated members, particularly, the processing target 20 which has entered the extremely narrow gaps between the laminations of the aluminum foil laminated electrodes and the windings of the copper coil to which the PCB which is difficult to remove by ordinary means adheres. An example of the processing will be described. The article 20 to which the PCB is adhered is put into the basket 6, stored in the autoclave 1, and sealed. Then
By driving the pump 9 attached to the pipe 4, if the cleaning agent 17 of the present invention in the cleaning agent tank 2 is required, the temperature of the cleaning agent 17 is adjusted by the heater 10, sent, and the spray nozzle 7 attached to the upper part of the autoclave 1. Then, if necessary, the temperature is adjusted by the cooling pipe 8 and the object to be processed 20 in the basket 6 is sprayed under pressure.

The sprayed cleaning agent of the present invention has both the permeability with n-butyl acetate and the solubility with β-oxyethyl methyl ether, and further, is treated with a spray nozzle 7 as a fine mist under pressure. Since it comes into contact with the object 20, it easily and effectively penetrates into the extremely narrow gap between the lamination of the electrodes of the object to be processed 20 and the winding of the copper coil, and at the same time, the effect of the PCB is improved by the integral dissolution ability. Will be dissolved and removed. The workpiece 20 thus washed is taken out of the basket 6 and the residual PCB content is measured. The residual PCB content is substantially completely removed in the order of 0.4 to 2.0 mg / kg, and is of a level that does not cause a problem. I got a number.

Cleaning waste liquid 18 containing dissolved and removed PCB 18
Flows out from the lower part of the basket 6 to the bottom part of the autoclave 1 and is collected by the pipe 5 into the washing waste liquid tank 3 and stored. The recovered washing waste liquid 18 has a similar boiling point to the two components constituting the cleaning agent.
Can be separated and recovered, and if necessary, the components are replenished, adjusted, and reused. The used cleaning agent whose processing property has been reduced by repeating reuse can be incinerated after separating PCB components by distillation, and the exhaust gas does not contain air pollutants.

[0019]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples. Example 1 A PCB-contaminated capacitor element (aluminum foil electrode) was supplied to 5 Soxhlet extractors of the same specification at 10 g / unit.
Various solvents were injected at a rate of 200 ml / group, respectively, and extracted by heating. After 5 hours, the PCB content of each capacitor element was analyzed. Table 1 shows the results.

[0020]

[Table 1]

The PCB content of the capacitor element extracted with a mixture of 90% β-oxyethyl methyl ether and 10% n-butyl acetate (MCBA) of the present invention is PCE.
It showed a lower value than the PCB content when extracted with n-hexane or n-hexane, and it was revealed that there was the highest removal effect. Methyl lactate showed a higher removal effect than n-hexane when compared as a less toxic hydrocarbon-based detergent, but was inferior to MCBA and PCE of the present invention.

Example 2 1.5 kg of a capacitor element (aluminum foil electrode) contaminated with PCB was tested in a basket 6 for storing a sample in an autoclave 1 of the experimental apparatus shown in FIG. 1, and 13 liters of a solvent whose temperature was adjusted to 50 ° C. At a set flow rate of / h, the PCB elution treatment of spraying the above capacitor element with the spray nozzle 7 was performed on the three solvents of the present invention (MCBA), PCE and methyl lactate. In each case, a part of the capacitor element was sampled every 8 hours to measure the PCB content. Table 2 shows the results.

[0023]

[Table 2]

As is evident from Table 2, the content of PCB already decreased to less than 2 mg / kg in MCBA after 8 hours, and the dissolution effect was remarkably increased as compared with the other two. Was.

Example 3 A PCB container contaminated with PCB (iron) was placed in a sample storage basket 6 in the autoclave 1 of the experimental apparatus shown in FIG.
Each solvent was sprayed at a flow rate of 9 liters / h from the top of the capacitor element with a spray nozzle 7 while controlling the temperature, and the PCB surface concentration of each sample was 8 hours later. Was measured. Table 3 shows the results
Shown in

[0026]

[Table 3]

For iron containers, the cleaning effect of MCBA is slightly lower than that of PCE. However, since the North American standard for solid surface concentration (no standard in Japan) is 1 mg / m ² , it is particularly problematic in terms of concentration. It has fallen to the extent that it does not become. Regarding the magnetic insulator, the MCBA and PCE treatments showed that both the PCB surface concentrations were extremely low, indicating that both had the same effect.

Example 4 1.5 kg of a copper coil in a PCB-contaminated transformer was supplied to a sample basket 6 in an autoclave 1 of the experimental apparatus shown in FIG. Then, the copper coil was sprayed from the top at a flow rate of 9 liter / h, and after 8 hours, the PCB content of each sample was analyzed. Table 4 shows the results.

[0029]

[Table 4]

It was found that MCBA had a lower PCB content than PCE and a greater cleaning effect than PCE.

[0031]

According to the present invention, PCB contaminants are currently only required to be stored in Japan, and are not disposed of properly. On the other hand, in Europe and the United States, there is a situation where PCE, which is a cleaning agent used for cleaning PCB-contaminated containers and the like, can no longer be used. Under such circumstances, P which is excellent in the cleaning agent of the present invention comprising a mixture of β-oxyethyl methyl ether and n-butyl acetate.
It was found that there was a CB cleaning effect.

The cleaning effect of the cleaning agent of the present invention is equivalent to or better than that of the above-described PCE. Particularly, since the cleaning agent has a high permeability, it is difficult to dissolve it in electric equipment and the like. Penetrated into the extremely narrow gap of
It made it possible to easily elute CB. Based on this new knowledge, PCs of electric equipment etc.
By cleaning the B contaminants with the cleaning agent of the present invention,
It is possible to greatly improve the current unattended state.
In addition, there is a secondary effect that the transformer, capacitor, and the like from which the PCB has been washed away can be reused as a resource of iron or copper.

[0033] In addition, equipment and members with a PCB are currently handled by storage, but there is a risk of leakage to the environment due to a major disaster such as an earthquake or a fire, and these dangers can be eliminated. . Furthermore, the cleaning agents currently used in Europe and the United States, such as PCE and chlorofluorocarbons, are feared to have a great adverse effect on the global environment, such as destruction of the ozone layer. However, the cleaning agents of the present invention also have the advantage of having little effect on the global environment. have.

[Brief description of the drawings]

FIG. 1 is a schematic view of an experimental apparatus using an autoclave for confirming the processing effect of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Autoclave 2 Cleaning tank 3 Cleaning waste tank 4, 5 Piping 6 Basket 7 Spray nozzle 8 Cooling coil 9 Liquid pump 10 Heater 11, 12 Control valve 13 Deaeration valve 14, 15 Thermometer 16 Pressure gauge 17 Cleaning tank 18 Cleaning waste tank 19 Viewing window

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-7-128867 (JP, A) Solvent Handbook, Kodansha, Japan, September 1, 1985, 6th printing, p. 772-775 (58) Fields investigated (Int. Cl. ⁷ , DB name) C11D 7/26 C11D 7/50 A62D 3/00 CA (STN) CAOLD (STN) REGISTRY (STN) JICST file (JOIS)

Claims (1)

(57) [Claims] (1) β-oxyethyl methyl ether (CH ₂ O
A cleaning agent for PCB contaminants in which CH ₂ CH ₂ OH) and n-butyl acetate (CH ₃ COOCH ₂ CH ₂ CH ₂ CH ₃ ) are mixed.