JP2007253065A - White seizure removing method of glass product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To keep the quality of a glass product high after the removal of white seizure. <P>SOLUTION: The white seizure of the glass product is washed by ultrasonic washing using a washing agent to remove the white seizure from the glass product. Especially, the white seizure of the glass product is washed off by washing using an ultrasonic wave with a frequency of 20-400 KHz and a sound pressure of 10-150 mV. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical element such as an optical lens, a prism, a mirror, a wave plate, and a polarizing plate, particularly a glass optical element used in an optical head device for DVD (registered trademark) or Blu-ray (registered trademark) DVD (book). The present invention relates to a method for removing the white burn of these optical elements widely called glass products by ultrasonic cleaning.

  Conventionally, when white burns occur in glass products such as optical lenses, prisms, mirrors, and wave plates, polishing work is manually performed using an abrasive to remove the white burns from the glass products.

  It has also been proposed to remove white burns from glass products using a cleaning agent (see, for example, Patent Documents 1, 2, and 3).

  Here, for example, as described in paragraph 0002 of Patent Document 3, the optical glass is formed on the surface due to the attached chemical substances, moisture, etc. during the manufacturing process of the optical component or during storage. Produces cloudiness and foreign matter. This is what is usually called “white discoloration”.

In addition, it is known that ultrasonic cleaning is performed in the cleaning process to enhance the cleaning effect (see, for example, paragraph 0004 and patent document 4 of Patent Document 3).
Japanese Patent Publication No. 30-6684 JP-A-1-126245 JP-A-7-300348 JP 2000-301086 A

  However, when the white discoloration of the glass product is removed by hand polishing using an abrasive, the quality is uneven and the yield cannot be increased.

  In recent years, a three-wavelength type wave plate that can be used for each of CD, DVD, and Blu-ray DVD has been manufactured, and a special glass product is used for this type of wave plate. For example, Pyrex (registered trademark) (PYREX (registered trademark), made by Corning, which has the same transmittance as quartz, quartz, added boron oxide to lower the softening point of quartz glass and keep the expansion coefficient as small as possible Silica borate glass, easy to work with glass, and can withstand rapid heating and rapid cooling, so it is excellent for physics and chemistry experiments), Tempax, Tempax Float (registered trademark) (TEMPAX, TEMPAX FLOAT, SCHOTT AG. Compared with general soda glass, its thermal expansion coefficient is small, and it exhibits excellent heat resistance and impact resistance in all fields. Both sides are finished to a flat and smooth surface by the float process, and it has high light transmittance. Glass with excellent optical quality without optical distortion).

  These glass products have high transmittance in the wavelength region of 385 nm to 415 nm, but the unit price is high, and if the quality becomes uneven, the cost becomes even higher.

Moreover, when CeO ₂ is used as the abrasive, for example, as described in paragraph 0010 of Patent Document 3, CeO ₂ adheres to the surface of the glass product. Since CeO ₂ has a property of absorbing ultraviolet rays, glass products polished with CeO ₂ could not be used for Blu-ray (registered trademark) in a band of 385 nm to 415 nm close to ultraviolet rays.

  An object of the present invention is to provide a method for removing white discoloration from a glass product that allows the quality of the glass product to be maintained well after the white discoloration has been removed.

  Examples of the solution means of the present invention for solving the above-described problems are as follows.

(1) A method for removing white discoloration from a glass product, comprising cleaning the white discoloration of the glass product by ultrasonic cleaning using a cleaning agent to remove the white discoloration from the glass product.

(2) In the dimming method for removing glassware above, by ultrasonic cleaning frequency and 10~150mV sound pressure of 20～400KH _Z, characterized by washing the dimming of the glass products, glass products White burn removal method.

(3) In the dimming method for removing glassware above, by ultrasonic cleaning frequency and 10~150mV sound pressure of 20～400KH _Z, characterized by washing the dimming of the glass products, glass products White burn removal method.

(4) In the above-mentioned method for removing white discoloration of glass products, the method for removing white discoloration of glass products is characterized by having a rinsing step and a drying step after the step of washing white discoloration of glass products by ultrasonic cleaning. Method.

(5) A method for removing white discoloration from a glass product, wherein the surface of the glass product from which white discoloration has been removed is sealed with a sealant in the glass product removal method described above.

(6) The glass product, wherein the surface of the glass product from which the white burn has been removed by ultrasonic cleaning is sealed with a sealant.

  According to the present invention, the quality of the glass product can be maintained high and the yield can be improved after removing the white burn.

  Moreover, the method of the present invention is a glass product (optical element such as an optical lens, a prism, a mirror, a wave plate, a polarizing plate) in an optical head compatible with Blu-ray (registered trademark) in a band of 385 nm to 415 nm close to ultraviolet rays. It is possible to apply to.

Best Mode for Carrying Out the Invention

  The present invention is characterized by removing white burns of glass products by ultrasonic cleaning.

  In particular, the present inventor has not only simply used ultrasonic cleaning to remove white discoloration, but has also conducted extensive research to make it possible to completely clean white discoloration of glass products at a predetermined frequency and a predetermined sound pressure. Even after removing the white discoloration, the quality of the glass product was kept high, and the yield could be improved without damaging the surface of the glass product. As a result, glass products (optical elements such as optical lenses, prisms, mirrors, wave plates, polarizing plates, etc.) in optical heads compatible with Blu-ray (registered trademark) with a bandwidth of 385 nm to 415 nm close to ultraviolet rays are also glass products. It has become possible to remove white discoloration.

In a preferred glass product cleaning method (white burn removal method) of the present invention, a predetermined output, a predetermined frequency, and a predetermined sound pressure are employed. For example, the sound pressure frequency and 10~150mV of 20～400KH _z is preferred.

  In the preferred glass product cleaning method of the present invention (white burn removal method), in any one of the cleaning step in the cleaning tank, the rinsing cleaning (rinsing) step in the rinsing tank, the drying step, or In addition to the above steps, it is preferable to have a step of cleaning the white burn of the glass product by ultrasonic cleaning.

  Moreover, it is preferable to seal the surface of the glass product from which the white burn was removed after washing | cleaning with sealing agents (for example, a silica gel, an oxygen absorber, etc.).

  As shown in FIG. 1, in the washing | cleaning apparatus G for enforcing the white burn removal method of this invention, it wash | cleans, rinses, and dries with respect to a glass substrate in order.

  For example, the cleaning apparatus G includes cleaning steps A1 and A2 for ultrasonic cleaning with an alkaline cleaning agent, rinsing steps B1 to B3 for rinsing the cleaning agent with pure water, and isopropyl alcohol (hereinafter abbreviated as IPA). ) Or a fluorinated solvent called a drainer, and substitution steps C1 to C3 for replacing pure water with IPA or a fluorinated solvent, and a drying step D1 with IPA or fluorinated solvent are performed. Yes. Here, in the cleaning steps A1 and A2, the rinsing steps B1 and B2, and the replacement steps C1 to C3, as shown in FIG. 1, a plurality of ultrasonic oscillation baths are used.

  Note that the substitution steps C1 to C3 may be omitted. In addition, in the drying process, in addition to drying with an IPA fluorine-based solvent, warm pure water pulling drying, warm air (hot air) drying, and shake-off drying may be used.

  Depending on the takt time, the steps of cleaning, rinsing, and drying may be simplified to reduce the number of ultrasonic oscillation baths, or conversely, may be increased.

  Since the configuration of the cleaning apparatus G shown in FIG. 1 can be the one described in Patent Document 4, detailed description thereof is omitted here.

  Optimum examples of glass products used in the present invention are, for example, white plates (B270, D263), blue plates (BK-7), etc., which are wavelength plates for ordinary optical head devices. However, the present invention is not limited to such a glass product of a glass substrate, and may be a glass product such as an optical lens, a prism, or a mirror.

  Moreover, the preferable example of a cleaning agent and an ultrasonic wave is as follows.

(1) Cleaning agent The cleaning agent is preferably an aqueous alkaline detergent using a surfactant, but is not limited thereto, and may be a neutral cleaning agent. For example, a cleaning agent containing a small amount of caustic soda and caustic potash, a glycol-based cleaning agent, and the like can be given.

(2) Ultrasonic frequency (output) and sound pressure (index)
The frequency (output) of the ultrasonic wave is usually in the range of 20 to 400 kHz. Although it is preferable to use a frequency of about 20 kHz to 40 kHz, the frequency may be within a range of 20 to 400 kHz and the frequency may be changed for each stain.

  In general, the sound pressure (index) is preferably in the range of 10 to 150 mV.

  When the glass substrate was washed, rinsed, and dried so as to satisfy the conditions (1) and (2) described above, the following measurement results were obtained.

-Na surface precipitation amount The Na surface precipitation amount was as showing in FIG.

  XPS element concentration analysis was performed using a white 76 mm square glass plate. After the glass plate was washed by the method for removing white burns according to the present invention, the inspection was conducted with a particular focus on the central portion of the glass plate. The ratio of Si concentration and Na surface precipitation amount was approximately 0.30 before cleaning, but it did not reach 0.10 after cleaning, and Na and its compounds eluted on the surface were removed by this cleaning. It has been confirmed.

  As shown in FIG. 3, if the washed product (cleaned product) is left as it is (after natural standing), the re-eluted Na is combined with moisture and oxygen in the air, and white burns are generated. However, if it is sealed with silica gel or an oxygen absorbent after washing, white burns will not occur.

  In order to confirm whether there is a difference in the amount of Na deposited between the central portion and the end portion of the glass plate before and after the cleaning performed in the method for removing white burns of the present invention, a white plate 76 mm square glass plate was used. XPS element concentration analysis was performed.

  As shown in FIG. 4, the ratio between the Si concentration and the amount of precipitated Na is about 0.05 in both the central portion and the end portion, and has not reached 0.10. It was confirmed that it does not precipitate in

  As shown in FIG. 4, if the cleaned product is left as it is, it binds to moisture and oxygen in the air and Na precipitates on the surface. However, after cleaning, sealing with silica gel, oxygen absorbent, etc. By sealing with an agent, it is possible to prevent the occurrence of white burn.

-Surface roughness According to the method of removing white burn of the present invention, after washing, the white burn is removed, and the surface roughness is reduced at the center and the end of the glass plate.

  As shown in FIG. 5 (central part) and FIG. 6 (end part), it was confirmed that the surface roughness was reduced in both the central part and the end part of the glass plate.

-Appearance inspection When observed at a magnification of 2,000 using an electron microscope, it was confirmed that white discoloration was completely removed and the surface of the glass plate was washed cleanly.

-Contact angle Since contact wettability can improve surface wettability by the method of this invention, film | membrane adhesiveness can be improved.

-Transmittance Transmittance was measured before and after washing for removing the above-mentioned white burn. In particular, the transmittance was measured by paying attention to the difference in reflectance around λ = 660 nm.

  As shown in FIG. 2, the Rs polarized reflectance after washing was as follows.

・ Λ = 660 nm Rs> 98% (reflection angle 45 °)
・ Λ = 784nm Rs> 98% (reflection angle 45 °)
As can be seen from FIG. 2, the reflectance of 98% or more is maintained after the cleaning for removing the white burn.

A glass product suitable for removing white discoloration by the method of the present invention is not limited to the above-mentioned plate glass. Examples thereof include fluorine-containing glass for ultraviolet region (for example, CaF ₂ , LiF, etc.) used for semiconductor manufacturing devices, semiconductor inspection devices, exposure devices, scanning electron microscopes, and other ultraviolet region glasses.

Explanatory drawing which shows an example of the washing | cleaning apparatus for enforcing the method of this invention. The graph which shows the relationship between a wavelength and a reflectance before and after the white burn removal washing | cleaning by this invention. The graph which shows the change of the relationship between Si density | concentration and each element density | concentration before and after white burn removal washing | cleaning by this invention. The graph which shows the change of the relationship between Si density | concentration and each element density | concentration in the center part and edge part of a glass substrate before and after the white burn removal washing | cleaning by this invention. The graph which shows the change of the surface roughness of the center part of the glass substrate before and after white burn removal washing | cleaning by this invention. The graph which shows the change of the surface roughness of the edge part of a glass substrate before and after the white burn removal washing | cleaning by this invention.

Claims (6)

  A method for removing white burns from a glass product, comprising cleaning the white burns of the glass product by ultrasonic cleaning using a cleaning agent to remove the white burn from the glass product. In dimming method for removing the glass product according to claim 1, the ultrasonic cleaning frequency and 10~150mV sound pressure of 20～400KH _Z, characterized by washing the dimming of the glass products, glass products To remove white discoloration. In dimming method for removing the glass product according to claim 1, the ultrasonic cleaning frequency and 10~150mV sound pressure of 20～400KH _Z, characterized by washing the dimming of the glass products, glass products To remove white discoloration.   The method for removing white burn of glass products according to any one of claims 1 to 3, further comprising a rinsing step and a drying step after the step of washing the white burn of the glass product by ultrasonic cleaning. To remove white discoloration from glass products.   4. The method for removing white discoloration of glass products according to claim 1, wherein the surface of the glass product from which white discoloration has been removed is sealed with a sealant after cleaning. Burn removal method. A glass product, characterized in that the surface of the glass product from which white burns have been removed by ultrasonic cleaning is sealed with a sealant.

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