JP3326845B2 - Washing / drying method and washing / drying apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to optical elements such as lenses, prisms and mirrors, semiconductor wafers, mirror surface inserts for dies, metal and plastic parts having complicated shapes, presses and machined products. The present invention relates to a cleaning / drying method and an apparatus for cleaning an object to be cleaned by degrease cleaning with a vapor of a non-aqueous solvent or drying after precision cleaning.

[0002]

2. Description of the Related Art The above-described cleaning of an object to be cleaned is performed using a chlorinated solvent such as trichloroethane or methylene chloride or chlorofluorocarbon. Problems and ozone depletion. For this reason, Japanese Patent Application Laid-Open No. 2-198678 discloses a method of cleaning using these solvents in a closed space. In this method, an object to be cleaned is placed in a washing tank that can be freely sealed, a solvent is injected to such an extent that the object to be cleaned is immersed, and cleaning is performed. Further, vapor cleaning is performed while sending high-temperature vapor of the solvent while draining the liquid. By keeping the inside of the cleaning tank at a negative pressure, the solvent is prevented from leaking into the atmosphere.

[0003]

However, the conventional method is mainly for cleaning, and drying is dependent. That is, in the cleaning tank, the object to be cleaned is washed with a solvent and vapor and dried, and then the object to be cleaned is taken out. However, since the liquid condensed on the object to be washed is taken out without being removed, it is naturally dried in the atmosphere. There are many cases. Therefore, although the solvent does not flow out to the outside at the time of cleaning, the solvent flows out after the object to be cleaned is taken out, and there is an inconvenience that fundamental pollution cannot be prevented. Moreover, since drying is not actively performed, a separate drying step is required after washing.

[0004] Further, since the solvent is circulated without being purified, the solvent is contaminated with the passage of time, which causes a problem that high-precision precision cleaning cannot be performed. In addition, conventional methods use non-flammable solvents such as chlorofluorocarbons and chlorinated solvents,
It cannot be applied to non-aqueous solvents or flammable solvents such as alcohols from the viewpoint of safety.

The present invention has been made in view of the above circumstances, and is capable of performing not only washing but also drying, and is capable of circulating a solvent without contamination over time, and is a flammable non-aqueous system. An object of the present invention is to provide a vapor cleaning / drying method using a non-aqueous solvent that can safely use a solvent, and an apparatus therefor.

[0006]

According to the present invention, there is provided a cleaning / drying method according to the present invention, wherein the cleaning / drying tank is supplied with a non-aqueous solvent having a lower specific gravity than water and supplied only under reduced pressure. Cleaning and / or cleaning the object to be cleaned disposed therein;
Or a drying step for drying, a liquefaction step of liquefying while recovering and liquefying the vapor of the non-aqueous solvent used in the cleaning and drying step, after the vapor of the non-aqueous solvent is recovered from the cleaning and drying tank. A take-out step of introducing the atmosphere into the washing and drying tank to take out the object to be washed, a non-aqueous solvent liquefied in the liquefaction step is introduced into a separation tank storing water at the bottom of the tank, and a non-aqueous solvent is introduced into the water. A recovery step of separating the solvent and water with a specific gravity difference to recover only the liquid non-aqueous solvent, sending the liquid non-aqueous solvent recovered in the recovery step to a vapor generation tank to vaporize the non-aqueous solvent, A supply step of supplying steam into the washing and drying tank in the reduced pressure state.

Further, the washing / drying apparatus of the present invention applied to this method uses a non-aqueous solvent having a specific gravity smaller than that of water supplied under reduced pressure in a closed state to clean the object to be washed disposed inside the tank. A washing / drying tank for washing and / or drying only with steam, and a vapor of the non-aqueous solvent used in the washing / drying tank being liquefied and introduced into the water stored at the bottom of the tank, and A closed separation tank in which the non-aqueous solvent is separated by a specific gravity difference, a closed tank connected to the separation tank and storing a liquid non-aqueous solvent separated in the separation tank, and a supply from the tank. A vapor generating tank that heats and evaporates the liquid non-aqueous liquid agent to be vaporized in a sealed state, and a conduit that guides the vapor of the non-aqueous solvent vaporized in the vapor generating tank to the cleaning and drying tank. It is characterized by having.

[0008]

In the washing and drying method described above, since only the vapor of the non-aqueous solvent, which is supplied under reduced pressure and has a specific gravity smaller than that of water, is used, not only the steam cleaning but also the drying can be performed. In addition, the non-aqueous solvent used as the vapor is recovered and liquefied from the washing and drying tank, and then separated from water by a specific gravity difference in the water stored in the separation tank to form a liquid non-aqueous solvent. When the liquid non-aqueous solvent is collected and sent to a vapor tank to be vaporized, the liquid non-aqueous solvent is separated from dirt such as oils and fats into vapor due to a difference in boiling point. Therefore, precision cleaning can be performed by cleaning the object to be cleaned in the cleaning and drying tank with the steam.
In addition, since all processes are closed systems, safety can be ensured.

On the other hand, in the above-mentioned washing / drying apparatus, all of the washing / drying tank, the separation tank, the tank, and the vapor generation tank can be made to have a sealed structure. Separation due to the difference in specific gravity between the solvent and water, storage of the liquid non-aqueous solvent from which the water has been separated, and vaporization of this liquid non-aqueous solvent are systematically connected so that the non-aqueous solvent circulates. , Efficient processing becomes possible.

[0010]

FIG. 1 shows an embodiment of the present invention. This embodiment is roughly divided into a washing / drying unit 1, a recovery unit 2, and a steam generation unit 3 so as to be divided by a two-dot chain line.
The cleaning / drying means 1 performs degreasing cleaning or precision cleaning and drying of the object 4 to be cleaned, and in addition to this, also continuously performs cleaning → drying. The washing / drying means 1 includes a lid 1 that can be opened and closed.
1 is provided with a washing / drying tank 10 in which the inside is closed when the object 1 is closed. In the washing / drying tank 10, receiving members 12 such as nets and shelves on which the objects 4 to be washed are placed are provided in one or more stages. Have been. A heater 13 for keeping the bath 10 at a predetermined temperature is disposed on the outer side of the side and bottom surfaces of the washing / drying bath 10. The heating operation of the heat retaining heater 13 prevents non-aqueous solvent vapor from being condensed on the vapor in the washing and drying tank 10. The cleaning / drying tank 10 is for cleaning and / or drying an object to be cleaned by a non-aqueous solvent vapor (vapor) under reduced pressure, and for returning the inside of the cleaning / drying tank 10 from the reduced pressure state to the normal pressure state. A leak valve 14 is provided.

The collecting means 2 has a separation tank 20 and a tank 21 connected to the separation tank 20. Separation tank 20
Is sealed by a lid 20a, in which water W is stored. The separation tank 20 is provided with a circulation path 22 for circulating the water W to the separation tank 20. The circulation path 22 is provided with a vacuum pump 23 composed of a water-sealed pump for supplying a non-aqueous solvent vapor or dew from the washing / drying tank 10 to the upper part of the separation tank 20. Such a circulation path 2
2 is described along the route, 24 is a drain valve, 25
Is a strainer for filtering foreign substances, 26 is a pump for supplying water to the vacuum pump 23, and 27 is a condenser for cooling the mixed liquid of the non-aqueous solvent and water from the vacuum pump 23 to promote liquefaction. In addition, a coil-shaped cooling pipe 28 for performing cooling is provided in the separation tank 20, and a funnel 29 that guides the mixed solution that has passed through the vacuum pump 23 and the condenser 27 to the inside of the water tank W is provided. I have. In the separation tank 20, the non-aqueous solvent and water are separated by a difference in specific gravity. Due to such separation, the non-aqueous solvent in the washing / drying tank 10 is recovered in the separation tank 20 in either a vapor form or a liquid form. Separation tank 20
The tank 21 connected to is supplied with only the non-aqueous solvent separated in this way and temporarily stores it for reuse, and has a closed structure.

The steam generating means 3 comprises a vapor generating tank 30.
And a heater 31. The vapor generation tank 30 has a non-aqueous solvent stored therein and a heater 31.
A heating coil 32 is provided to supply the high-temperature and high-pressure steam from the heater to heat the non-aqueous solvent. Reference numeral 33 denotes a level meter for detecting the liquid level of the non-aqueous solvent in the vapor generation tank 30, and the supply of the non-aqueous solvent according to the detection value of the level meter 33 is performed. The heater 31 includes a heater 31a, and heats a heat medium provided therein. As the heater 31, an electric boiler, a factory steam or another heating mechanism can be selected. In the illustrated example, an electric boiler is used. The heater 31 is connected to a hot water tank 34, and the hot water in the tank 34 is supplied to a pump 35.
Is supplied to the heater 31 to be heated. This heating turns the hot water into steam, which is sent to the heating coil 32 of the vapor generation tank 30 and heats the non-aqueous solvent in the tank 30 to form vapor. The water vapor after heating becomes a liquid condensed by the auto trap 36 and is collected in the hot water tank 34 and reused. The liquid level of the hot water in the hot water tank 34 is detected by a liquid level gauge 37, and a predetermined amount is constantly stored.

The washing and drying means 1 and the collecting means 2 as described above.
The steam generating means 3 is connected by a piping described below to form a closed system in which the non-aqueous solvent circulates. First, the washing / drying means 1 and the recovery means 2 are connected by two systems of a main pipe and a sub pipe. The main piping is the bottom of the washing and drying tank 10 and the collecting means 2
And a pipe 51 for discharging the liquid non-aqueous solvent condensed in the washing and drying tank 10 and a vacuum pump 23 to connect the upper part of the washing and drying tank 10 to the non-aqueous solvent. And a conduit 52 for discharging the vapor. An exhaust valve 5 that opens and closes is provided in these pipelines 51 and 52.
3 and 54 are provided, and a condenser 55 for cooling and liquefying the vapor is provided in the conduit 52.

On the other hand, as shown by a two-dot chain line,
A pipe 56 connects the bottom of the washing / drying tank 10 to the exhaust valve 54 of the pipe 52 of the main pipe, and a pipe 59 directly connects the bottom of the washing / drying tank 10 and the tank 21 of the recovery means 2. The pipe 59 has an exhaust valve 57 and a condenser 58.
Is provided. These main pipes and sub-pipes are arranged according to the discharge status of the non-aqueous solvent in the washing and drying tank 10.
Used alternatively or simultaneously.

The piping connecting the collecting means 2 and the steam generating means 3 is constituted by a pipe 60 arranged between the tank 21 of the collecting means 2 and the vapor generating tank 30 of the steam generating means 3. The pipe 60 is provided with a liquid feed pump 61, a filter 62 for removing foreign substances by filtration, an automatic valve 63 and a check valve 64. The liquid feed pump 61 operates based on the detection signal of the level meter 33 of the vapor generation tank 30 and supplies the non-aqueous solvent in the tank 21 to the vapor generation tank 30. The liquid feed pump 61 is controlled so as to operate when the non-aqueous solvent in the vapor generation tank 30 reaches a predetermined lower limit, and stop when the non-aqueous solvent reaches a predetermined upper limit.

A pipe connecting the steam generating means 3 and the washing / drying means 1 is constituted by a pipe 70 connecting the vapor generating tank 30 and the washing / drying tank 10, and an air supply valve 71 is provided in the pipe 70. Is provided. In addition, an air supply valve 72 and a throttle valve 73 are arranged in the pipe 70 so as to be in parallel with the air supply valve 71. In FIG. 1, reference numeral 80 denotes a temperature controller provided in the vapor generation tank 30 and the heater 31; and 81, a pressure controller for detecting and controlling the pressure in the vapor generation tank 30 and the heater 31.

Next, the operation of this embodiment will be described. Examples of the non-aqueous solvent for washing the article to be washed 4 include linear or cyclic siloxane compounds, benzene compounds such as terpenes, and the like.
Alcohols such as IPA (isopropyl alcohol) and ethanol, and other compounds are appropriately selected and used.
These solvents are flammable, but since this embodiment is a closed system as a whole, it can be safely washed or dried without volatilizing to the outside. First, while the washing / drying tank 10 is heated by the heat retaining heater 13, the article 4 to be washed is set on the receiving member 12 of the tank 10, and the lid 11 is closed and sealed. The object to be cleaned may be one that has been subjected to normal cleaning in which replacement with IPA is performed after cleaning with a surfactant, rinsing with city water, and rinsing with pure water, or an untreated material that has not been cleaned. Can be applied.

The exhaust valves 53 and 54 are opened while the washing and drying tank 10 is closed, and the vacuum pump 23 is operated, whereby the inside of the washing and drying tank 10 is depressurized. When a predetermined degree of vacuum is attained by the reduced pressure, the exhaust valves 53 and 54 are closed. On the other hand, in the steam generating means 3, the non-aqueous solvent in the vapor generating tank 30 is heated by the heater 31 to generate vapor of the non-aqueous solvent. In this state, the air supply valves 71 and 72 of the pipe 70 are opened to introduce the vapor into the washing and drying tank 10. The vapor is supplied to a predetermined concentration in the cleaning / drying tank 10, and thereby the object 4 to be cleaned is cleaned with a non-aqueous solvent vapor.

After performing such a vapor cleaning for a predetermined time,
The air supply valves 71 and 72 are closed, and the exhaust valves 53 and 54 are opened. At this time, since the vacuum pump 23 is operating, the vapor and the condensate of the non-aqueous solvent in the washing and drying tank 10 are sucked and removed from the pipes 51 and 52. At this time, the vapor is liquefied by the condenser 55 in the pipe 52. The sucked non-aqueous solvent is mixed with water by a vacuum pump 23, and the remaining vapor is liquefied by a condenser 27.
Will be introduced. By liquefying the non-aqueous solvent in the washing and drying tank 10 with the condensers 55 and 27 in this manner, the recovery rate of the non-aqueous solvent can be improved. After the inside of the washing / drying tank 10 is sucked, the air is introduced by opening the leak valve 14 while closing the exhaust valves 53 and 54, whereby washing and drying by the vapor are completed, and the article 4 to be washed is taken out.

The non-aqueous solvent introduced into the separation tank 20 is recovered by being separated from water by its specific gravity difference, and the overflowed non-aqueous solvent is transferred to the tank 21. On the other hand, in the vapor generation tank 30, the liquid level inside is detected by the level meter 33. When the liquid level reaches the lower limit, the liquid supply pump 61 is driven and the non-aqueous solvent is removed from the tank 21.
Is supplied to the vapor generation tank 30, and the shortage thereof is replenished. The separation tank 20 separates a non-aqueous solvent by a specific gravity difference from water. However, when an alcohol such as IPA is used as the non-aqueous solvent, a water-alcohol separation device is used instead of the separation tank 20. , To separate them.

In such washing or drying, since the treatment is carried out by a closed system, the non-aqueous solvent does not leak or diffuse to the outside. Therefore, effective prevention of pollution can be achieved without the non-aqueous solvent polluting the atmosphere and the environment. In addition, since washing and drying are performed under reduced pressure, oxygen is almost shut off, safety is improved even with flammable non-aqueous solvents, and washing and drying can be performed at low temperatures, and thermal Damage can also be reduced. Further, since the non-aqueous solvent is recovered by the recovery means 2 and recycled,
Its effective use is possible. Moreover, when the recovered non-aqueous solvent is vaporized in the vapor generation tank 30, it is separated from fats and oils due to a difference in boiling point, so that it can be recycled and used in a state of high purity, and has a strong detergency and drying power. can do.

In the above embodiment, the non-aqueous solvent in the washing / drying tank 10 is recovered by the main pipe composed of the pipes 51 and 52, but may be recovered by the sub-pipe composed of the pipes 56 and 59. . In this case, after the object to be cleaned 4 is washed, the air supply valves 71 and 72 are closed and the exhaust valve 57 of the pipe 59 is opened. As a result, the liquid of the non-aqueous solvent condensed in the washing and drying tank 10 flows directly into the tank 21 after passing through the condenser 58. In conjunction with this, the leak valve 14 is opened for a short time and the exhaust valves 53 and 54 are opened to apply the suction force of the vacuum pump 23. As a result, the vapor of the non-aqueous solvent in the washing / drying tank 10 is
After being liquefied through 7, it flows into the separation tank 20 and is separated from water in the separation tank 20.

[0023]

As described above, according to the cleaning / drying method and the cleaning / drying apparatus of the present invention, the non-aqueous solvent does not diffuse to the outside and the treatment is performed under reduced pressure. It is safe to use a solvent, and washing and drying subsequent to washing can be performed. In addition, since the non-aqueous solvent can be recovered, regenerated and recycled, efficient treatment can be performed, and precision cleaning and drying can be performed.

[Brief description of the drawings]

FIG. 1 is a piping diagram showing an embodiment of the present invention.

[Description of Signs] 1 Cleaning / drying means 2 Recovery means 3 Steam generation means 4 Object to be cleaned 10 Cleaning / drying tank 20 Separation tank 21 Tank 30 Vapor generation tank 31 Heater

Continuation of the front page (72) Inventor Sadayuki Ono 2-43-2 Hatagaya, Shibuya-ku, Tokyo O-Limpus Optical Industry Co., Ltd. (72) Inventor Masato Tanaka 75-five-five-story casting founder shop in Shohani, Nagano Prefecture Chiyoda Co., Ltd. (56) References JP-A-2-198678 (JP, A) JP-A-58-139705 (JP, A) (58) Fields studied (Int. Cl. ⁷ , DB name) B08B 3/10

Claims (2)

(57) [Claims] 1. A cleaning and drying method for cleaning and / or drying an object to be cleaned disposed in a cleaning / drying tank only by using a vapor of a non-aqueous solvent having a lower specific gravity than water and supplied to the cleaning / drying tank. A liquefaction step of recovering and liquefying the vapor of the non-aqueous solvent used in the cleaning / drying step from within the cleaning / drying tank, and in the cleaning / drying tank after the vapor of the non-aqueous solvent is recovered from the cleaning / drying tank. Taking out the object to be cleaned by introducing the air into the non-aqueous solvent liquefied in the liquefaction step, introduced into a separation tank storing water at the bottom of the tank, the non-aqueous solvent and water in the water A recovery step of collecting only the liquid non-aqueous solvent separated by a specific gravity difference, sending the liquid non-aqueous solvent recovered in the recovery step to a vapor generation tank to vaporize the non-aqueous solvent, In the washing and drying tank Washing drying method characterized in that it comprises a supply step of feeding. 2. A washing and drying tank for washing and / or drying an object to be washed disposed inside the tank only with steam of a non-aqueous solvent having a lower specific gravity than water supplied under reduced pressure in a closed state. The closed state in which the vapor of the non-aqueous solvent used in the washing and drying tank is liquefied and introduced into the water stored at the bottom of the tank, and the non-aqueous solvent is separated by a specific gravity difference from water in the water. A separation tank, a sealed tank connected to the separation tank and storing a liquid non-aqueous solvent separated in the separation tank, and a liquid non-aqueous liquid agent supplied from the tank is heated in a sealed state. A cleaning and drying apparatus, comprising: a vapor generation tank that vaporizes; and a conduit for guiding the vapor of the non-aqueous solvent vaporized in the vapor generation tank to the cleaning and drying tank.