JPH06126260A - Ultrasonic washing method and washing liquid - Google Patents

Abstract

PURPOSE:To prevent the use of washing liquid whose waste liquid treatment is difficult and to prevent a decrease in washing ability in giving ultrasonic washing to lenses, etc., by mixing granules having hardness smaller than that of a material to be washed and specific gravity approximately equal to that of the washing liquid in the washing liquid to perform washing. CONSTITUTION:In the 1st washing tank 1, washing liquid where granules 20 of about 1-3mm particle diameter which polyurethane resin is used as a base material and cerium oxide is bound to it to form are mixed in isopropyl alcohol is used. In the 2nd washing tank 2, washing liquid 11 is isopropyl alcohol. In the 3rd washing tank 3, washing liquid 12 where granules 24 which shells of walnuts are crushed to about 1-3mm particle diameter to form are mixed in pure water is used. In the 4th washing tank 4, washing liquid 13 is pure water. And lenses 15 are given ultrasonic washing in the 1st washing tank 1 to the 4th washing tank 4 by the ultrasonic vibration of ultrasonic oscillators 5-8 respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic cleaning method and a cleaning liquid for ultrasonic cleaning.

[0002]

2. Description of the Related Art When forming an optical thin film on the surface of an optical component such as a lens or a prism by vacuum vapor deposition or sputtering, it is necessary to maintain stable optical characteristics or prevent the optical thin film from peeling off. , Its surface should be kept clean. For this purpose, ultrasonic cleaners have been widely used recently and are effective not only for cleaning optical components but also for cleaning various components and materials that require cleanliness.

In the ultrasonic cleaning machine, a cleaning tank equipped with an ultrasonic vibrator is filled with the cleaning liquid, and the ultrasonic vibrator is driven while the object to be cleaned is immersed in the cleaning liquid. As a result, the cleaning liquid vibrates with ultrasonic waves (usually about 20 kHz to 50 kHz), and the strong acceleration generated in the liquid and the impact pressure resulting from the disappearance of cavitation act on the surface of the object to be cleaned.

Most of the ultrasonic cleaning machines used in the production process have the above-mentioned cleaning tanks arranged in a plurality of stages, and various cleaning liquids are used according to the kind of the object to be cleaned and the type of dirt. For example, in an optical component whose lens surface is processed by using a curve generator or the like, cooling oil or the like may be attached to the surface, and in order to remove it, an organic solvent such as trichlene, xylene or isopropyl alcohol may be used. It is used as a cleaning liquid. In the final cleaning step, a volatile organic solvent such as Freon (trade name) is also used.

[0005]

However, in the above-mentioned organic solvent, isoprovir alcohol is water-soluble and relatively easy to treat the waste liquid, but trichlene and xylene are not soluble in water, so the waste liquid is treated as industrial waste. It has to be treated and is cumbersome to handle. Further, although Freon is water-soluble, it is preferably not used as much as possible in order to avoid environmental pollution.

The present invention has been made in consideration of the above circumstances, and it is possible to use a cleaning liquid which is troublesome in waste liquid treatment as much as possible,
Moreover, it is an object of the present invention to provide an ultrasonic cleaning method and a cleaning liquid that do not reduce the cleaning ability.

[0007]

Means for Solving the Problems To achieve the above object, the present invention performs ultrasonic cleaning by mixing particles having a hardness smaller than that of an object to be cleaned and having a specific gravity almost the same as that of the cleaning solution. I decided to do it. Further, in view of the constitution as a cleaning liquid, the cleaning liquid of the present invention can be regarded as a mixed liquid of a liquid and a large number of particles having a specific gravity almost equal to that of the liquid.

[0008]

When ultrasonic vibration is applied to the cleaning liquid containing the above-mentioned particles, the liquid itself enhances the cleaning effect by the same mechanism as before, and the particles collide with the surface of the object to be cleaned with a large acceleration and become dirty. Will be scraped off and the cleaning effect can be further enhanced. Therefore, even if the detergency of the liquid itself is lowered to some extent, the granules act to compensate for this, so that high detergency can be obtained even when pure water or isopropyl alcohol is used as the liquid.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 schematically shows an ultrasonic cleaning machine for cleaning a lens, and as shown in the drawing, a first cleaning tank 1, a second cleaning tank 2,
It has four cleaning tanks, a third cleaning tank 3 and a fourth cleaning tank 4.
Ultrasonic vibrators 5 to 8 are attached to the bottom of each cleaning tank, and by driving these, ultrasonic vibration is applied to the cleaning liquids 10 to 13 contained in each cleaning tank.

The lenses 15, which are objects to be cleaned, are arranged in a cleaning basket 16 so that they do not come into contact with each other, and after a predetermined cleaning time has elapsed, they are sequentially transferred from the first cleaning tank 1 to the fourth cleaning tank. When cleaning is performed in each cleaning tank, the ultrasonic vibrator is driven, and the ultrasonic vibration of the cleaning liquid removes dirt.

The cleaning liquid 10 contained in the first cleaning tank 1 is
Granules 20 in isopropyl alcohol as a liquid
Is mixed in. The granules 20 are made of polyurethane resin as a base material and bound with cerium oxide, and have a particle diameter of about 1 to 3 mm. The hardness of the granules 20 is smaller than the hardness of the glass material of the lens 15. The weight mixing ratio of polyurethane resin and cerium oxide is
It is adjusted to be about the same as the specific gravity of isopropyl alcohol (about 0.8). The cleaning liquid 11 in the second cleaning tank 2 is isopropyl alcohol.

The cleaning liquid 12 contained in the third cleaning tank 3 is
Pure water is used as the liquid, and the particles 24 are mixed therein. As the granules 24, walnut shells crushed to a particle size of about 1 to 3 mm are used, and their specific gravity is almost the same as that of pure water. The cleaning liquid 13 in the fourth cleaning tank 4 is pure water.

When ultrasonic cleaning is performed in the first cleaning tank 1, the granules 20 also vibrate ultrasonically. Therefore, in addition to the impact caused by the generation and disappearance of cavitation due to the ultrasonic vibration of the liquid, the collision of the particles 20 is also added, so that the cleaning effect is higher than the ultrasonic cleaning using only the liquid. Even if oil or the like is adhered to the surface of the lens 16 as a film, it can be removed by scraping it off.

Since the hardness of the granules 20 is smaller than that of the lens 16, even if the granules 20 collide with the lens surface, they are not scratched. Moreover, since the specific gravity of the granules 20 is about the same as that of the liquid, it does not settle or float in the liquid,
The density in the liquid can be kept almost constant. In addition,
Various other materials such as polyethylene and polystyrene can be used as the resin base material for the granules 20, and aluminum oxide, red iron oxide, etc. can be used as the binder.

In the second cleaning tank 2, ultrasonic cleaning is further performed with isopropyl alcohol. And the third cleaning tank 3
Then, in addition to the ultrasonic vibration of pure water, the ultrasonic vibration of the particles 24 is also used. Therefore, for the same reason as the cleaning in the first cleaning tank 1, the cleaning effect can be enhanced as compared with the ultrasonic cleaning using pure water only. After cleaning with pure water in the fourth cleaning tank 4, the lens 15 is taken out together with the cleaning basket 16 and dried by a centrifugal dryer or the like. The lens 15 thus obtained has a very clean surface and can be immediately sent to the next step of forming an optical thin film.

As described above, the collision of the particles with the surface to be cleaned enhances the cleaning effect as compared with the ultrasonic cleaning using only the liquid as in the past, so that the cleaning power of the liquid itself is somewhat reduced. Even if it does, it can be compensated by mixing the particles. Therefore, instead of conventionally using a harmful organic solvent as the cleaning liquid, it is also possible to use a liquid in which particles are mixed in a liquid that can be easily disposed of. It should be noted that since the number of particles decreases as the cleaning is repeated, the particles may be replenished appropriately while confirming the cleaning effect. Alternatively, a cleaning liquid containing a predetermined amount of particles may be prepared in advance, and the entire amount may be replaced when the cleaning effect decreases.
Further, when the particles are excessively mixed in the liquid, it is feared that the propagation efficiency of ultrasonic vibrations may be lowered and the cleaning ability may be deteriorated. Therefore, the weight mixing ratio of the particles to the liquid is 5 to 5. It is better to keep it in the range of about 30%.

Although the above description has been made in accordance with the illustrated example, the liquid in which the particles are mixed is not limited to isopropyl alcohol and pure water, and may be, for example, depending on the type and degree of the object to be cleaned or the dirt. It is possible to use an appropriate liquid such as alcohol mixed with a liquid detergent or a solution mixed with two kinds of liquids such as pure water. Further, as the granules, those having appropriate material composition, specific gravity, hardness and particle diameter can be used. Further, even in the ultrasonic cleaning machine, the number and types of cleaning tanks are not limited to the illustrated example, and the present invention can be applied to a single tank type ultrasonic cleaning machine.

[0018]

As described above, according to the present invention, since the ultrasonic cleaning is performed using the cleaning liquid in which the particles are mixed, the impact of the ultrasonic vibration of the particles can be utilized for the cleaning. The cleaning effect can be greatly improved. Since the hardness of the granules is smaller than that of the object to be cleaned, the object to be cleaned is not scratched, and by adjusting the specific gravity to the same level as the liquid, the particles settle or float in the liquid. Therefore, the cleaning efficiency can be stably maintained.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an ultrasonic cleaning machine using the present invention.

[Explanation of symbols]

 1 1st cleaning tank 2 2nd cleaning tank 3 3rd cleaning tank 4 4th cleaning tank 10-13 Cleaning liquid 20,24 Granules

Claims (2)

[Claims] 1. An object to be cleaned is dipped in a cleaning liquid in a cleaning tank,
In the ultrasonic cleaning method in which ultrasonic vibration is applied to the cleaning liquid, cleaning is performed by mixing granules with hardness less than that of the object to be cleaned and having almost the same specific gravity as the cleaning liquid into the cleaning liquid. Ultrasonic cleaning method. 2. A cleaning liquid used for ultrasonic cleaning, wherein the cleaning liquid is a mixed liquid of a liquid and a large number of particles having substantially the same specific gravity as the liquid.